EP0566449B1 - Hydraulic maximum load and pressure compensating valve - Google Patents

Hydraulic maximum load and pressure compensating valve Download PDF

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Publication number
EP0566449B1
EP0566449B1 EP93400866A EP93400866A EP0566449B1 EP 0566449 B1 EP0566449 B1 EP 0566449B1 EP 93400866 A EP93400866 A EP 93400866A EP 93400866 A EP93400866 A EP 93400866A EP 0566449 B1 EP0566449 B1 EP 0566449B1
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EP
European Patent Office
Prior art keywords
pressure
passage
channel
plunger
fluid
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP93400866A
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German (de)
French (fr)
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EP0566449A1 (en
Inventor
Michel Rivolier
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Rexroth Sigma SA
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Rexroth Sigma SA
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
    • F15B13/0416—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor with means or adapted for load sensing
    • F15B13/0417—Load sensing elements; Internal fluid connections therefor; Anti-saturation or pressure-compensation valves
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/87169—Supply and exhaust
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/87169—Supply and exhaust
    • Y10T137/87177—With bypass
    • Y10T137/87185—Controlled by supply or exhaust valve

Definitions

  • the detection system load consists, in a set of distributors controlling respective loads requiring different hydraulic powers, to detect which of the loads which requires the highest power, and therefore the highest pressure for the hydraulic working fluid which supplies it, and to bring this highest pressure to a control input of the pump so as to control the latter as required.
  • This function is carried out by providing, in each distributor, a selector which is sensitive, on the one hand, to the pressure of the working fluid supplied to the load controlled by the distributor and, on the opposite side, to the pressure of the working fluid supplied to another load controlled by a distributor and which is capable of selecting the higher of these two pressures; by selection step by step, it is the highest pressure of the entire hydraulic system which ultimately ensures the control of the pump.
  • the load detection lines are conventionally supplied by a pressure tap made at the level of the load.
  • the load detection line is supplied first, before the load is. If this detection line has a leak (such a leak can in particular be created voluntarily for certain operating modes of the hydraulic circuit), the control pressure applied to the load begins to decrease before rising to the nominal value imposed by the distributor.
  • the load an arm articulated by example
  • this pressure compensation leads in particular to pass part of the necessary hydraulic connections through the slide. Drilling the corresponding conduits in the drawer considerably increases the manufacturing cost thereof. In addition, the presence of these conduits drilled through the drawer clogs the internal volume thereof and it is then it is no longer possible to provide other drillings useful for other purposes, for example those required by the implementation of a load braking system. These other systems must then be designed in the form of piped external circuits, which further adds to the complexity and cost of the assembly.
  • the pilot pressure of the pump differs from the pressure of the pressurized fluid supplied by the pump not only from the value of the pressure drop imposed by the pressure compensation means, but also of the value of the pressure drop which is introduced by the non-return function provided by the valve of the most loaded distributor and which corresponds to the value of the calibration of the valve return spring.
  • the presence of the return spring disturbs the theoretical operation of the system, which proves to be a notable drawback which is particularly noticeable in the range of very low pressures.
  • the object of the invention is therefore essentially to remedy the drawbacks presented by current hydraulic distributors of the type with pressure compensation and selection of the highest pressure and to propose an improved distributor which better meets the various requirements of the practice, and which in particular is of a simpler structural and constructive technology and therefore of a lower cost, which retains the same operating sensitivity throughout the pressure range, including for very low pressures, and above all which is arranged so that the control of the variable flow pump which feeds this distributor is ensured in a more efficient manner independent of the reactions of the load.
  • the combination and mutual integration of the pressure compensation means and the highest pressure selection means leads to a considerable simplification of the internal structure of the distributor by eliminating the particular channels and the specific selector provided up to present to constitute the means for selecting the highest pressure and to ensure this selection function.
  • the pressure selection means can be constituted in a very simple structural form as it appears below, one understands all the interest of the improvement brought by the invention both at the level of the manufacturing (much less machining in the body and fewer component parts, therefore much lower manufacturing cost) than in terms of use and maintenance (reduction of possible sources of malfunction, reduction of maintenance).
  • the arrangement in accordance with the invention notably improves the operating reliability of the hydraulic system built around the distributor.
  • the arrangement of the distributor is such that, in the case where the pressure in the distributor is higher than the pressure in the load detection line channel, communication is established directly between the transmitting passage the pressurized fluid and the channel. In this way, the pressure which reigns in said channel is the pressure of the fluid coming from the pump and a possible leak in the line connected to said channel does not have the unfavorable influence reported above in the current devices.
  • the pressure compensation means and the maximum pressure selection means are unique and selectively connectable to the two working orifices.
  • a non-return valve can be provided in the above passage, between the pressure compensation means and each working orifice. It is then possible to provide, depending on the needs and the structure adopted, a single non-return valve in the above passage, between the pressure compensation means and a working orifice, or two non-return valves in the above passage , between the pressure compensation means and respectively two working orifices.
  • the pressure compensation means combined with the maximum pressure selector means further comprise elastic return means acting on the movable plunger in a direction identical to the direction of action of the pressure prevailing in the channel: in the absence of pressure, the plunger is thus held in abutment by its head against a corresponding retaining shoulder.
  • the distributor which is represented therein comprises a body 1 provided with an orifice P for admission of the pressurized fluid (constituted in the form of a channel 2 passing through the body 1 transversely to the plane of the drawing and opening onto the two main faces of said body serving as support during stacking side by side and one against the other of several distributors), of at least one orifice T (formed in the form a channel passing through the body 1 transversely to the plane of the drawing and emerging on the two main faces of said body) for the return of the fluid to a reservoir (not shown), two orifices A, B for connection to a hydraulic device or component (not shown), and a drawer 4 capable of sliding in a bore 5 of the body 1; the bore 5 passes longitudinally through the body 1 and opens onto two opposite faces, or end faces 6, 7 thereof.
  • the pressurized fluid constituted in the form of a channel 2 passing through the body 1 transversely to the plane of the drawing and opening onto the two main faces of said body serving as support during stacking side by side and one against the other of several
  • the body 1 and the drawer 4 have passages and / or pipes and / or grooves arranged so as to cooperate with a view to establishing the desired connections or closings of the various orifices of the body of the dispenser according to the position. occupied by the drawer.
  • the arrangements specific to the invention of these passages and / or pipes and / or grooves will be indicated later.
  • the body 1 comprises yet another transverse channel 8 extending between the main faces of the body and combined with at least one pressure selector making it possible to transmit, in the channel 18 downstream of the distributor, the highest (pressure " load sensing "or pressure LS) of the two pressures constituted respectively by the pressure upstream of the distributor and a working pressure of the distributor.
  • the channel 8 opens into a cavity, hollowed out in the corresponding main face of the body (a cavity 9 is visible in Figure 1).
  • the positioning of the cavities on the main faces is such that, when stacking two distributors face to face, the cavity 9 provided on a main face of one and the cavity provided on the main cooperating face of the other cooperate to constitute a chamber in which is housed a seal (not shown), whereby said channel 8 passes right through the control block consisting of a stack of several distributors regardless of the number of these.
  • a seal not shown
  • the channel 2 connected to the intake orifice P opens into the bore 5 of the body in an intake chamber 10 thereof, near which another chamber 11 communicates, through a passage 12, with a housing 13 in which a plunger 14 is mounted in free sliding movement.
  • the passage 12 opens into the housing 13 at one end thereof (corresponding to an end face of the plunger 14), while at its opposite end the housing 13 opens into a cavity 15 in which the head 16 of the plunger 14 can move.
  • the head 16, enlarged relative to the body of the plunger bears on a shoulder formed at the outlet of the housing 13 in the cavity 15 to retain the plunger 14.
  • a spring 17 may be provided in the cavity 15 to push the plunger 14 against said shoulder so as to fix its position in the absence of pressure.
  • the aforementioned channel 8 is in communication with the cavity 15, so that the pressure prevailing in the channel 8 is also present in the cavity 15 and is then exerted on the corresponding end of the plunger 14.
  • the plunger 14 is crossed by an axial channel 18 opening on one side in its end face opposite the passage 12 and on the other side in a diametral channel 19 passing through the plunger 14 and arranged so as to be closed by the wall of the housing 13 when the plunger 14 is in the rest position imposed by the spring 17 (shown in Figure 1) or in a position not fully raised as will appear below.
  • the portion of the drawer 4 which extends, in the neutral position, between the chambers 10 and 11 by isolating them from one another is provided with progressivity notches 20 intended to ensure a controlled flow of the hydraulic fluid in the direction suitable when the drawer is moved in one direction or the other.
  • FIG. 2 shows a variant according to which a single duct 21 is provided from the housing 13, with a single non-return valve 22 beyond which the duct 21 splits into two branches 21 a , 21 b , joining the two chambers 23 respectively.
  • the distributor is part of a multiple control block constituted by a stack, face to face, of several identical distributors (an exemplary embodiment will be given below), in which the orifices P, T and 9 provided on the main faces communicate with each other; in particular, the channels 8 constitute a line for transmitting the highest pressure (“load sensing” line or LS line) which is connected to a control input of a variable flow pump (not shown), the output of which pressure is connected to ports P.
  • the plunger begins to move (upwards in the drawing) as shown in the Figure 3, to come into a new equilibrium position in which the pressure in the passage 12 is equal to the pressure LS increased by the force of the calibration spring.
  • the plunger then partially clears the inlet of the conduit 21 and the fluid flows by this path while undergoing a constant pressure drop whatever the flow rate and regulated by the difference between the intake pressure and the LS pressure.
  • the non-return valve 22 (the one located on the right in FIG. 3 in the example considered) opens and the fluid flow is routed towards the orifice B.
  • the plunger 14 behaves like a valve. (or balance) of traditional pressure regulation.
  • the pressure in the chamber 12 becomes such that the plunger 14 lifts up as far as possible, clearing the inlet of the duct 21 as much as possible, while the channel 19 of the plunger comes out into the cavity 15. Fluid from the passage 12 then flows, through the channels 18 and 19, in the cavity 15 and, thereby, in the channel 8: the distributor considered thus imposes its control pressure as LS pressure.
  • the plunger 14 behaves as the highest pressure selector in the control line LS of the pump.
  • the interest of the distributor arranged in accordance with the invention is due both to the structural simplification which it represents (the same plunger serves both as pressure compensator and pressure selector for the LS line, while two separate elements , correspondent two separate hydraulic circuits, have been used up to now) and the greater control accuracy of the pump that it drives: in fact, in the previous circuits, the pressure LS was taken from the working pressure itself or charge pressure (for example at the level of the outlets) with the drawbacks exposed at the beginning of this description, while, in the distributor arranged according to the invention, the line LS is supplied by the highest pressure coming directly from the pump and a possible leak in the LS line no longer influences the load (in particular is no longer likely to cause the load to drop).
  • the drawer is simple in design, without internal channels, and its manufacture is made easier and less expensive.
  • a distributor arranged according to the invention makes it possible to keep the hydraulic circuit in which it is included the advantage of a flow division operation that cannot be obtained by the only "load sensing" system, that is to say that in a saturated circuit the speeds of all the receivers are reduced in proportion to the respective bit rates in these receivers and there is therefore slowing down or immobilization of the receiver having the highest load.
  • FIG. 5 shows an alternative embodiment of the hydraulic distributor in accordance with the invention, in which the pressure compensation and highest pressure selection circuit is split respectively in correspondence with the two starting circuits A and B.
  • same reference numerals have been used to designate the same members as for the dispenser of FIG. 1; the two cavities 15 are joined to a single LS8 channel.
  • the operation remains identical to what has been described above, except that a single plunger is in operation according to the direction of movement of the slide 4 and depending on whether the departure is made through the orifice A or the orifice B.
  • FIG. 6 is a diagram illustrating an example of a multiple control hydraulic circuit using a multiple hydraulic control block using a stack of several distributors according to the invention.
  • the hydraulic control unit comprises a stack of several distributors D1, D2 ..., D n , the inlet ports P, return T and pump control LS of which are all joined together by the simple tight juxtaposition of the faces main bodies of distributors, in a manner well known to those skilled in the art.
  • a blind terminal element 28 is mounted at one end of the stack to close the respective conduits P, T and LS of the stack; this terminal element could for certain applications be provided with a pressure reducing device (not shown).
  • An inlet element 29 is transparent for the inlet line P which is connected to the outlet under pressure from a source of pressurized fluid with variable flow rate -which may for example be a variable flow pump P p as shown in Figure 6 or even a fixed flow pump with open center valve - and for the return line T which is connected to a tank R.
  • a source of pressurized fluid with variable flow rate - which may for example be a variable flow pump P p as shown in Figure 6 or even a fixed flow pump with open center valve - and for the return line T which is connected to a tank R.
  • the line LS is connected, in the input element 29, to the return line T through a first flow regulator such as a nozzle or throttle 30 intended to allow the decompression of the entire device when the flow is zero (i.e. when all the distributors are in neutral position).
  • a first flow regulator such as a nozzle or throttle 30 intended to allow the decompression of the entire device when the flow is zero (i.e. when all the distributors are in neutral position).
  • the charge detection control pressure LS p intended for the pump is taken from the line LS, upstream of the first nozzle 30, through a second nozzle 31.
  • This nozzle 31 has the function of recreating a pressure drop at the terminals of the plunger 14 of each of the distributors of the block.
  • a single nozzle 31 is placed in the inlet element 29.
  • a limiting valve 32 intended to limit the maximum value of the charge detection control pressure when the pump is operating at its maximum flow rate, is interposed between the line LS p and the return line T.
  • FIG. 7 is a diagram illustrating another example of a hydraulic multiple control circuit using a multiple hydraulic control block using a stack of several distributors arranged according to the invention. This arrangement differs from that of FIG. 6 by the fact that a nozzle 31 is here provided in each of the distributors, in place of the single nozzle 31 previously housed in the input element 29.
  • the inlet element without the nozzle is designated by the reference 29 ', while the distributors each equipped with a nozzle 31 are respectively designated D'respectivement, D'2, ..., D' n .
  • D'1, D'2, ..., D ' n a very simplified representation of the distributor is given, accompanied by the numerical references used in FIG. 1, so as to show the situation of the nozzle 31.
  • the nozzle 31 is interposed between the load detection line channel 8 and the distribution chamber 11; this nozzle is made functional when a communication is established between the passage 12 and the channel 8 by the displacement of the plunger 14 and it is arranged to create a pressure drop lower than the setting of the spring of the plunger of the distributor which it equips.
  • FIG. 8 shows an example of installation of the nozzle 31.
  • the nozzle 31 is housed in the upper, narrow part of the axial channel 18 drilled in the plunger and connecting the diametral channel 19 drilled in the plunger with the passage 12.
  • the adaptation of the distributor for this type of circuit is therefore easy and inexpensive to carry out.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Control Of Positive-Displacement Pumps (AREA)

Description

La présente invention concerne des perfectionnements apportés aux distributeurs hydrauliques combinant une compensation de pression et une sélection de pression maximale (ou la plus élevée) pour le pilotage d'une pompe d'alimentation (système dit "de détection de charge" ou "load sensing") et, plus particulièrement, elle concerne des perfectionnements apportés à un distributeur hydraulique à compensation de pression, comportant :

  • un corps de distributeur ;
  • un tiroir logé dans le corps pour pouvoir y être déplacé longitudinalement pour une transmission sélective d'un fluide hydraulique sous pression vers des orifices de travail prévus dans le corps à partir d'un orifice d'admission du fluide hydraulique sous pression ;
  • un passage dans ledit corps pour relier aux orifices de travail une chambre de distribution, associée au tiroir et apte à être reliée sélectivement à l'orifice d'admission par le tiroir déplacé ;
  • un canal de ligne de détection de charge (load sensing) combiné avec des moyens sélecteurs de pression la plus élevée agencés pour établir dans ledit canal la pression la plus élevée sélectionnée parmi la pression règnant dans ledit canal et la pression du fluide sous pression du distributeur ; et
  • des moyens de compensation de pression placés dans ledit passage et sensibles à la différence entre la pression de fluide dans le distributeur et la pression règnant dans ledit canal, afin d'engendrer une chute de pression sensiblement fixe dans le fluide sous pression s'écoulant en direction des orifices de travail.
The present invention relates to improvements made to hydraulic distributors combining pressure compensation and maximum (or highest) pressure selection for controlling a supply pump (so-called "load sensing" or "load sensing" system). ") and, more particularly, it relates to improvements made to a hydraulic distributor with pressure compensation, comprising:
  • a distributor body;
  • a drawer housed in the body in order to be able to be displaced longitudinally therein for a selective transmission of a pressurized hydraulic fluid to working orifices provided in the body from an inlet port for pressurized hydraulic fluid;
  • a passage in said body for connecting to the working orifices a distribution chamber, associated with the drawer and capable of being selectively connected to the inlet orifice by the displaced drawer;
  • a load sensing line channel combined with highest pressure selector means arranged to establish in said channel the highest pressure selected from the pressure prevailing in said channel and the pressure of the fluid under pressure of the distributor ; and
  • pressure compensation means placed in said passage and sensitive to the difference between the fluid pressure in the distributor and the pressure prevailing in said channel, in order to generate a substantially fixed pressure drop in the pressurized fluid flowing in direction of the work orifices.

On rappellera brièvement que le système de détection de charge consiste, dans un ensemble de distributeurs commandant des charges respectives nécessitant des puissances hydrauliques différentes, à détecter celle des charges qui nécessite la puissance la plus élevée, et donc la pression la plus élevée pour le fluide hydraulique de travail qui l'alimente, et à ramener cette pression la plus élevée sur une entrée de commande de la pompe de manière à asservir celle-ci aux besoins. Cette fonction est réalisée en prévoyant, dans chaque distributeur, un sélecteur qui est sensible, d'un côté, à la pression du fluide de travail fournie à la charge commandée par le distributeur et, du côté opposé, à la pression du fluide de travail fournie à une autre charge commandée par un distributeur et qui est apte à sélectionner la plus élevée de ces deux pressions ; par une sélection de proche en proche, c'est la pression la plus élevée de l'ensemble du système hydraulique qui assure finalement le pilotage de la pompe.It will be recalled briefly that the detection system load consists, in a set of distributors controlling respective loads requiring different hydraulic powers, to detect which of the loads which requires the highest power, and therefore the highest pressure for the hydraulic working fluid which supplies it, and to bring this highest pressure to a control input of the pump so as to control the latter as required. This function is carried out by providing, in each distributor, a selector which is sensitive, on the one hand, to the pressure of the working fluid supplied to the load controlled by the distributor and, on the opposite side, to the pressure of the working fluid supplied to another load controlled by a distributor and which is capable of selecting the higher of these two pressures; by selection step by step, it is the highest pressure of the entire hydraulic system which ultimately ensures the control of the pump.

La mise en place, au sein des distributeurs, des moyens (sélecteurs et canaux de liaison) nécessaires à la réalisation d'un sytème de détection de charge a conduit à une complexité notable de la structure des distributeurs. Des solutions de simplification ont pu être trouvées pour certains types de distributeurs, mais aucune n'a été trouvée à ce jour pour les distributeurs à fonctionnement proportionnel.The installation, within distributors, of the means (selectors and link channels) necessary for the creation of a load detection system has led to a noticeable complexity in the structure of the distributors. Simplification solutions have been found for certain types of distributors, but none has been found to date for proportional distributors.

Par ailleurs, les lignes de détection de charge sont classiquement alimentées par une prise de pression faite au niveau de la charge. Au tout début d'une phase de distribution, la ligne de détection de charge se trouve alimentée en premieu lieu, avant que la charge ne le soit. Si cette ligne de détection présente une fuite (une telle fuite peut notamment être créée volontairement pour certains modes de fonctionnement du circuit hydraulique), la pression de commande appliquée à la charge commence par décroître avant de remonter à la valeur nominale imposée par le distributeur. Il en résulte que la charge (un bras articulé par exemple) commence par descendre avant de monter conformément à la commande qui lui est imposée et, dans tous les cas, il se produit un à-coup au moment du rétablissement des conditions normales. Il s'agit là d'un réel inconvénient du système, qui peut se révéler dangereux.Furthermore, the load detection lines are conventionally supplied by a pressure tap made at the level of the load. At the very start of a distribution phase, the load detection line is supplied first, before the load is. If this detection line has a leak (such a leak can in particular be created voluntarily for certain operating modes of the hydraulic circuit), the control pressure applied to the load begins to decrease before rising to the nominal value imposed by the distributor. As a result, the load (an arm articulated by example) begins by descending before ascending in accordance with the command which is imposed on it and, in all cases, it occurs suddenly when the normal conditions are restored. This is a real drawback of the system, which can be dangerous.

D'autre part, dans un distributeur hydraulique classique, le débit du fluide hydraulique délivré par l'orifice de travail du distributeur subit des fluctuations en fonction de son importance déterminée par la position du tiroir et en fonction de la pression fournie par la pompe. Il est connu (par exemple US 3 827 453) de pallier cet inconvénient et de rendre le débit du fluide de travail constant quelles que soient les circonstances en prévoyant dans le distributeur des moyens de compensation de pression qui comparent en permanence la pression de travail en provenance de la pompe à une valeur de consigne fixe ou variable ; dans ce dernier cas, il peut s'agir de la pression la plus élevée sélectionnée dans la ligne de détection de charge, afin de laminer le fluide de travail en conséquence et de crée ainsi une chute de pression constante dans ce fluide de travail.On the other hand, in a conventional hydraulic distributor, the flow rate of the hydraulic fluid delivered by the working orifice of the distributor is subject to fluctuations as a function of its importance determined by the position of the slide and as a function of the pressure supplied by the pump. It is known (for example US 3 827 453) to overcome this drawback and to make the flow of the working fluid constant whatever the circumstances by providing in the distributor pressure compensation means which constantly compare the working pressure in source of the pump at a fixed or variable setpoint; in the latter case, it may be the highest pressure selected in the load detection line, in order to laminate the working fluid accordingly and thus creates a constant pressure drop in this working fluid.

Dans des distributeurs connus (par exemple US 4 693 272), la présence de ces moyens de compensation de pression vient encore ajouter à la complexité de la structure car lesdits moyens de compensation de pression, bien qu'utilisant l'information de pression la plus élevée présente dans la ligne de détection de charge, sont établis indépendamment des moyens mis en oeuvre pour la sélection de la pression la plus élevée.In known distributors (for example US 4,693,272), the presence of these pressure compensation means further adds to the complexity of the structure since said pressure compensation means, although using the most pressure information present in the load detection line, are established independently of the means used for selecting the highest pressure.

En outre, la mise en oeuvre de cette compensation de pression conduit notamment à faire passer une partie des liaisons hydrauliques nécessaires à travers le tiroir. Le perçage des conduits correspondants dans le tiroir accroît considérablement le coût de fabrication de celui-ci. De plus, la présence de ces conduits percés à travers le tiroir encombre le volume interne de celui-ci et il n'est alors plus possible de prévoir d'autres perçages utiles à d'autres fins, par exemple ceux exigés par la mise en oeuvre d'un système de freinage de charge. Ces autres systèmes doivent alors être conçus sous forme de circuits extérieurs tuyautés, ce qui ajoute encore à la complexité et au coût de l'ensemble.In addition, the implementation of this pressure compensation leads in particular to pass part of the necessary hydraulic connections through the slide. Drilling the corresponding conduits in the drawer considerably increases the manufacturing cost thereof. In addition, the presence of these conduits drilled through the drawer clogs the internal volume thereof and it is then it is no longer possible to provide other drillings useful for other purposes, for example those required by the implementation of a load braking system. These other systems must then be designed in the form of piped external circuits, which further adds to the complexity and cost of the assembly.

Dans d'autres distributeurs connus (US 5 138 837, EP 0 438 606), on trouve certes une tentative de simplification et d'intégration des moyens de compensation de pression et des moyens de détection de charge. Toutefois les moyens de détection de charge demeurent agencés avec une prise de pression située dans la ligne reliée à la charge : ces distributeurs connus présentent donc toujours les inconvénients mentionnés précédemment pour ce type d'agencement.In other known distributors (US 5 138 837, EP 0 438 606), there is certainly an attempt to simplify and integrate the pressure compensation means and load detection means. However, the load detection means remain arranged with a pressure tap located in the line connected to the load: these known distributors therefore always have the drawbacks mentioned above for this type of arrangement.

On peut encore ajouter que, dans les distributeurs connus dont la fonction de compensation de pression est assurée par un clapet rappelé par un ressort, la pression de pilotage de la pompe diffère de la pression du fluide sous pression fourni par la pompe non seulement de la valeur de la chute de pression imposée par les moyens de compensation de pression, mais aussi de la valeur de la perte de charge qui est introduite par la fonction anti-retour assurée par le clapet du distributeur le plus chargé et qui correspond à la valeur du tarage du ressort de rappel du clapet. Ainsi, dans un tel agencement, la présence du ressort de rappel perturbe le fonctionnement théorique du système, ce qui s'avère un inconvénient notable particulièrement sensible dans la plage des très faibles pressions.It can also be added that, in known distributors whose pressure compensation function is provided by a valve recalled by a spring, the pilot pressure of the pump differs from the pressure of the pressurized fluid supplied by the pump not only from the value of the pressure drop imposed by the pressure compensation means, but also of the value of the pressure drop which is introduced by the non-return function provided by the valve of the most loaded distributor and which corresponds to the value of the calibration of the valve return spring. Thus, in such an arrangement, the presence of the return spring disturbs the theoretical operation of the system, which proves to be a notable drawback which is particularly noticeable in the range of very low pressures.

L'invention a donc essentiellement pour but de remédier aux inconvénients présentés par les distributeurs hydrauliques actuels du type à compensation de pression et à sélection de la pression la plus élevée et de proposer un distributeur perfectionné qui donne mieux satisfaction aux diverses exigences de la pratique, et qui en particulier soit d'une technologie structurelle et constructive plus simple et donc d'un coût moins élevé, qui conserve la même sensibilité de fonctionnement dans toute la plage de pression, y compris pour les très faibles pressions, et surtout qui soit agencé de manière que le pilotage de la pompe à débit variable qui alimente ce distributeur soit assuré d'une manière plus efficace et indépendante des réactions de la charge.The object of the invention is therefore essentially to remedy the drawbacks presented by current hydraulic distributors of the type with pressure compensation and selection of the highest pressure and to propose an improved distributor which better meets the various requirements of the practice, and which in particular is of a simpler structural and constructive technology and therefore of a lower cost, which retains the same operating sensitivity throughout the pressure range, including for very low pressures, and above all which is arranged so that the control of the variable flow pump which feeds this distributor is ensured in a more efficient manner independent of the reactions of the load.

A ces fins, l'invention propose un distributeur à compensation de pression du type indiqué au préambule qui, étant agencé conformément à l'invention, se caractérise essentiellement en ce que les moyens de compensation de pression sont combinés avec les moyens sélecteurs de pression la plus élevée et en ce qu'il existe des moyens de liaison sélective aptes à établir sélectivement une liaison entre le canal et le passage en amont des moyens de compensation de pression de manière telle que :

  • . si la pression dans le canal est supérieure ou égale à la pression du fluide dans le passage en amont des moyens de compensation de pression, aucune communication n'existe entre ledit passage et ledit canal et la pression dans le canal conserve sa valeur,
    ou bien,
  • . si la pression dans le canal est inférieure à la pression du fluide dans le passage en amont des moyens de compensation de pression, une communication est établie entre ledit passage en amont des moyens de compensation de pression et ledit canal et la pression dans le canal devient celle du fluide présent dans le passage en amont des moyens de compensation de pression.
For these purposes, the invention provides a pressure compensation distributor of the type indicated in the preamble which, being arranged in accordance with the invention, is essentially characterized in that the pressure compensation means are combined with the pressure selector means the higher and in that there are selective connection means capable of selectively establishing a connection between the channel and the passage upstream of the pressure compensation means such that:
  • . if the pressure in the channel is greater than or equal to the pressure of the fluid in the passage upstream of the pressure compensation means, no communication exists between said passage and said channel and the pressure in the channel retains its value,
    or,
  • . if the pressure in the channel is lower than the pressure of the fluid in the passage upstream of the pressure compensation means, a communication is established between said passage upstream of the pressure compensation means and said channel and the pressure in the channel becomes that of the fluid present in the passage upstream of the pressure compensation means.

Grâce aux dispositions conformes à l'invention, la combinaison et l'intégration mutuelle des moyens de compensation de pression et des moyens de sélection de pression la plus élevée conduit à une simplification considérable de la structure interne du distributeur par suppression des canaux particuliers et du sélecteur spécifique prévus jusqu'à présent pour constituer les moyens de sélection de la pression la plus élevée et assurer cette fonction de sélection. Il ne subsiste désormais qu'un canal unique traversant directement (par exemple dans le sens de la largeur) le corps du distributeur, à hauteur d'une extrémité des moyens de compensation de pression. Comme, par ailleurs, les moyens de sélection de pression peuvent être constitués sous une forme structurelle très simple comme cela apparaît ci-après, on comprend tout l'intérêt du perfectionnement apporté par l'invention tant au niveau de la fabrication (beaucoup moins d'usinage dans le corps et moins de pièces constitutives, donc coût de fabrication beaucoup moins élevé) qu'au niveau de l'utilisation et de l'entretien (diminution des sources possibles de mauvais fonctionnement, réduction de l'entretien).Thanks to the arrangements in accordance with the invention, the combination and mutual integration of the pressure compensation means and the highest pressure selection means leads to a considerable simplification of the internal structure of the distributor by eliminating the particular channels and the specific selector provided up to present to constitute the means for selecting the highest pressure and to ensure this selection function. There now remains only a single channel passing directly (for example in the width direction) the body of the distributor, up to one end of the pressure compensation means. As, moreover, the pressure selection means can be constituted in a very simple structural form as it appears below, one understands all the interest of the improvement brought by the invention both at the level of the manufacturing (much less machining in the body and fewer component parts, therefore much lower manufacturing cost) than in terms of use and maintenance (reduction of possible sources of malfunction, reduction of maintenance).

Surtout l'agencement conforme à l'invention améliore notablement la fiabilité de fonctionnement du système hydraulique construit autour du distributeur. En effet, on a vu que l'agencement du distributeur est tel que, dans le cas où la pression dans le distributeur est plus élevée que la pression dans le canal de ligne de détection de charge, une communication est établie directement entre le passage transmettant le fluide sous pression et le canal. De la sorte, la pression qui règne dans ledit canal est la pression du fluide en provenance de la pompe et une fuite éventuelle dans la ligne raccordée audit canal n'a pas l'influence défavorable signalée plus haut dans les dispositifs actuels.Above all, the arrangement in accordance with the invention notably improves the operating reliability of the hydraulic system built around the distributor. Indeed, we have seen that the arrangement of the distributor is such that, in the case where the pressure in the distributor is higher than the pressure in the load detection line channel, communication is established directly between the transmitting passage the pressurized fluid and the channel. In this way, the pressure which reigns in said channel is the pressure of the fluid coming from the pump and a possible leak in the line connected to said channel does not have the unfavorable influence reported above in the current devices.

De préférence, dans un mode de réalisation structurellement simple, les moyens de compensation de pression combinés avec les moyens sélecteurs de pression maximale comprennent

  • un alésage prévu dans le corps et relié, à une extrémité, audit passage en provenance de la chambre commandée par le tiroir et, à son autre extrémité, audit canal de ligne de détection de charge,
  • un plongeur mobile de commande libre de coulisser dans ledit alésage sous l'action des pressions s'exerçant sur ses extrémités opposées,
  • des premiers moyens obturateurs disposés dans ledit passage du fluide sous pression, solidaires dudit plongeur,
  • des seconds moyens obturateurs disposés dans une connexion entre ledit passage de fluide sous pression et ledit canal, solidaires dudit plongeur, ledit plongeur étant apte à occuper :
    • . une première position extrême ou position de fermeture double, occupée en l'absence du fluide sous pression, dans laquelle les premiers et seconds moyens obturateurs sont fermés,
    • . un ensemble de positions intermédiaires, occupées lorsque du fluide sous pression est présent dans le passage, la position du plongeur étant déterminée par la différence entre la pression dans le passage et la pression dans le canal alors que celle-ci est supérieure à celle-là, dans laquelle les seconds moyens obturateurs sont maintenus fermés et les premiers moyens obturateurs sont ouverts avec un degré d'ouverture propre à provoquer dans l'écoulement de fluide sous pression une chute de pression prédéterminée,
    • . et une seconde position extrême ou position d'ouverture double, occupée lorsque la pression du fluide dans le passage est supérieure à la pression dans le canal, pour laquelle les premiers moyens obturateurs sont ouverts au maximum et les seconds moyens obturateurs sont eux aussi ouverts en établissant une communication entre ledit passage et ledit canal.
Preferably, in a structurally simple embodiment, the pressure compensation means combined with the maximum pressure selector means comprise
  • a bore provided in the body and connected, at one end, to said passage coming from the chamber controlled by the slide and, at its other end, to said load detection line channel,
  • a movable plunger for free control of sliding in said bore under the action of pressures exerted on its opposite ends,
  • first shutter means arranged in said passage of the pressurized fluid, integral with said plunger,
  • second shutter means arranged in a connection between said passage of pressurized fluid and said channel, integral with said plunger, said plunger being able to occupy:
    • . a first extreme position or double closed position, occupied in the absence of the pressurized fluid, in which the first and second shutter means are closed,
    • . a set of intermediate positions, occupied when pressurized fluid is present in the passage, the position of the plunger being determined by the difference between the pressure in the passage and the pressure in the channel when the latter is greater than that , in which the second shutter means are kept closed and the first shutter means are open with a degree of opening capable of causing a predetermined pressure drop in the flow of pressurized fluid,
    • . and a second extreme position or double opening position, occupied when the pressure of the fluid in the passage is greater than the pressure in the channel, for which the first shutter means are opened to the maximum and the second shutter means are also open in establishing communication between said passage and said channel.

Dans un exemple particulier de réalisation, il est avantageux que :

  • la partie dudit passage reliée à la chambre commandée par le tiroir communique avec une extrémité de l'alésage,
  • la partie dudit passage reliée aux orifices de travail s'ouvre radialement dans l'alésage,
  • lesdits premiers moyens obturateurs sont constitués par ledit plongeur réalisé sous forme allongée de manière que
    • . dans sa première position extrême, il obture totalement ladite ouverture du passage,
    • . dans son ensemble de positions intermédiaires, il obture partiellement ladite ouverture pour créer la chute de pression prédéterminée
    • . et dans sa seconde position extrême, il dégage au maximum ladite ouverture.
In a particular embodiment, it is advantageous that:
  • the part of said passage connected to the chamber controlled by the slide communicates with one end of the bore,
  • the part of said passage connected to the working orifices opens radially into the bore,
  • said first shutter means are constituted by said plunger produced in elongated form so that
    • . in its first extreme position, it completely closes said opening of the passage,
    • . in its set of intermediate positions, it partially seals said opening to create the predetermined pressure drop
    • . and in its second extreme position, it releases said opening as much as possible.

Dans ce dernier cas, on peut prévoir que les seconds moyens obturateurs sont constitués par ledit plongeur muni d'un conduit interne débouchant, d'un côté, dans la face du plongeur soumise à l'action de la pression du fluide dans le passage et, de l'autre côté, radialement au voisinage de l'autre face du plongeur qui est soumise à la pression du canal, de manière que :

  • . quand le plongeur est dans sa première position extrême et dans son ensemble de positions intermédiaires, le débouché radial dudit conduit soit obturé par l'alésage et
  • . quand le plongeur est dans sa seconde position extrême, le débouché radial dudit conduit soit sorti de l'alésage et en communication avec ledit canal.
In the latter case, provision may be made for the second shutter means to be constituted by said plunger provided with an internal conduit opening, on one side, into the face of the plunger subjected to the action of the pressure of the fluid in the passage and , on the other side, radially in the vicinity of the other face of the plunger which is subjected to the pressure of the channel, so that:
  • . when the plunger is in its first extreme position and in its set of intermediate positions, the radial outlet of said duct is closed by the bore and
  • . when the plunger is in its second extreme position, the radial outlet of said conduit is out of the bore and in communication with said channel.

Dans un exemple de réalisation simple, les moyens de compensation de pression et les moyens de sélection de pression maximale, combinés ensembles, sont uniques et reliables sélectivement aux deux orifices de travail.In a simple embodiment, the pressure compensation means and the maximum pressure selection means, combined together, are unique and selectively connectable to the two working orifices.

Toutefois, il est également possible, tout au moins en vue de certaines applications particulières pour lesquelles la disposition précédente ne peut pas être retenue et qui exigent une indépendance totale des deux voies hydrauliques conduisant respectivement aux deux orifices de travail du distributeur, que les moyens de compensation de pression et les moyens de sélection de pression maximale, combinés ensembles, soient doubles et associés respectivement aux deux orifices de travail.However, it is also possible, at least for certain specific applications for which the previous provision cannot be adopted and which require total independence of the two hydraulic paths leading respectively to the two working orifices of the distributor, that the pressure compensation means and the maximum pressure selection means, combined together, are double and associated respectively with the two working orifices.

Pour écarter l'influence d'une surpression dans l'orifice de travail, on peut prévoir un clapet anti-retour dans le susdit passage, entre les moyens de compensation de pression et chaque orifice de travail. Il est alors possible de prévoir, selon les besoins et la structure adoptée, un seul clapet anti-retour dans le susdit passage, entre les moyens de compensation de pression et un orifice de travail, ou bien deux clapets anti-retour dans le susdit passage, entre les moyens de compensation de pression et respectivement deux orifices de travail.To eliminate the influence of an overpressure in the working orifice, a non-return valve can be provided in the above passage, between the pressure compensation means and each working orifice. It is then possible to provide, depending on the needs and the structure adopted, a single non-return valve in the above passage, between the pressure compensation means and a working orifice, or two non-return valves in the above passage , between the pressure compensation means and respectively two working orifices.

Il est souhaitable de ramener le plongeur dans une position prédéterminée lorsqu'il n'est soumis à aucune pression, et pour cela on prévoit que les moyens de compensation de pression combinés avec les moyens sélecteurs de pression maximale comprennent en outre des moyens de rappel élastique agissant sur le plongeur mobile dans un sens identique au sens d'action de la pression règnant dans le canal : en l'absence de pression, le plongeur est ainsi maintenu en appui par sa tête contre un épaulement de retenue correspondant.It is desirable to return the plunger to a predetermined position when it is not subjected to any pressure, and for this it is provided that the pressure compensation means combined with the maximum pressure selector means further comprise elastic return means acting on the movable plunger in a direction identical to the direction of action of the pressure prevailing in the channel: in the absence of pressure, the plunger is thus held in abutment by its head against a corresponding retaining shoulder.

Grâce aux moyens mis en oeuvre dans le cadre de l'invention, on constate que toutes les liaisons fluidiques peuvent être prévues dans le corps seul du distributeur et qu'il n'est pas nécessaire de prévoir certaines liaisons à travers le tiroir comme c'était au contraire le cas jusqu'à présent dans les distributeurs de l'art antérieur. La suppression de ces usinages spécifiques permet de réduire les coûts de fabrication du tiroir ou bien, à tout le moins, laisse de la place disponible pour équiper le tiroir de liaisons prévues à d'autres fins, notamment pour assurer des fonctions supplémentaires n'intéressant pas la sélection de la pression la plus élevée et/ou la compensation de pression.Thanks to the means used in the context of the invention, it can be seen that all of the fluid connections can be provided in the body of the dispenser alone and that it is not necessary to provide certain connections through the drawer like this. on the contrary was the case until now in distributors of the prior art. The elimination of these specific machinings makes it possible to reduce the costs of manufacturing the drawer or, at the very least, leaves space available to equip the drawer with connections provided for other purposes, in particular to ensure additional functions not relevant to the selection of the highest pressure and / or pressure compensation.

L'invention propose également un dispositif de commande hydraulique multiple interposé entre une source de fluide sous pression à débit variable et un réservoir de retour, d'un côté, et plusieurs organes de charge hydrauliques devant être commandée respectivement et sélectivement à partir de ladite source. Dans un premier exemple de réalisation possible, ce dispositif comprend un empilement côte-à-côte

  • de plusieurs distributeurs hydrauliquea agencés conformément à l'invention tels que décrits plus haut,
  • d'un élément terminal,
  • et d'un élément d'entrée qui est transparent pour les lignes P et T des distributeurs empilés reliés respectivement à la sortie sous pression de la source et au réservoir de retour,
    qui comporte un régulateur de débit de décompression interposé entre une ligne de commande de la source par détection de charge issue des distributeurs empilés et la ligne de retour,
    et qui comporte un gicleur interposé entre la ligne de commande de la source par détection de charge issue des distributeurs empilés et l'entrée de commande de la source, ce gicleur étant agencé pour créer une chute de pression aux bornes du plongeur de chaque distributeur ; avantageusement, dans un tel circuit, entre la sortie de second gicleur et la ligne de retour est interposé un circuit limiteur de la pression de commande de pompe par détection de charge apte à limiter ladite pression de commande lorsque la pompe fournit sa pression maximale.
The invention also provides a multiple hydraulic control device interposed between a source of fluid under pressure with variable flow rate and a return tank, on one side, and several hydraulic load members to be controlled respectively and selectively from said source. . In a first possible embodiment, this device comprises a side-by-side stack
  • several hydraulic distributors arranged in accordance with the invention as described above,
  • of a terminal element,
  • and an input element which is transparent to the lines P and T of the stacked distributors connected respectively to the pressure outlet of the source and to the return tank,
    which includes a decompression flow regulator interposed between a source control line by load detection from the stacked distributors and the return line,
    and which comprises a nozzle interposed between the source control line by load detection from the stacked distributors and the source control input, this nozzle being arranged to create a pressure drop across the terminals of the plunger of each distributor; advantageously, in such a circuit, between the output of the second nozzle and the return line is interposed a circuit limiting the pump control pressure by load detection capable of limiting said control pressure when the pump provides its maximum pressure.

Dans un autre exemple de réalisation possible, ce dispositif comprend un empilement côte-à-côte

  • de plusieurs distributeurs hydrauliques agencé comme indiqué plus haut, chaque distributeur comportant un gicleur interposé entre le canal de ligne de détection de charge et la chambre de distribution, ce gicleur étant rendu fonctionnel lorsque une communication est établie entre le passage et le canal et étant agencé pour créer une chute de pression aux bornes du plongeur du distributeur,
  • d'un élément terminal,
  • et d'un élément d'entrée qui est transparent pour les lignes P et T des distributeurs empilés reliés respectivement à la sortie sous pression de la source et au réservoir de retour, et
    qui comporte un régulateur de débit de décompression interposé entre une ligne de commande de la source par détection de charge issue des distributeurs empilés et la ligne de retour.
In another possible embodiment, this device comprises a side-by-side stack
  • of several hydraulic distributors arranged as indicated above, each distributor comprising a nozzle interposed between the load sensing line channel and the distribution chamber, this nozzle being made functional when a communication is established between the passage and the channel and being arranged to create a pressure drop across the distributor plunger,
  • of a terminal element,
  • and an input element which is transparent to the lines P and T of the stacked distributors connected respectively to the pressurized outlet of the source and to the return tank, and
    which includes a decompression flow regulator interposed between a source control line by load detection from the stacked distributors and the return line.

L'invention sera mieux comprise à la lecture de la description détaillée qui suit d'un mode de réalisation préféré donné uniquement à titre d'exemple purement illustratif. Dans cette description, on se réfère aux dessins annexés sur lesquels :

  • la figure 1 est une vue en coupe d'un distributeur hydraulique agencé conformément à l'invention, le tiroir dudit distributeur étant disposé en position neutre ou inactive ;
  • la figure 2 est une vue en coupe d'une variante de réalisation du distributeur de la figure 1 ;
  • les figures 3 et 4 sont des vues en coupe du distributeur de la figure 1 montrant celui-ci respectivement dans deux autres positions fonctionnelles différentes ;
  • la figure 5 est une vue en coupe d'encore une autre variante d'un distributeur hydraulique agencé selon l'invention ;
  • la figure 6 est un schéma illustrant un exemple de constitution d'un circuit de commande hydraulique multiple incluant des distributeurs conforme à l'invention;
  • la figure 7 est un schéma illustrant un autre exemple de constitution d'un circuit de commande hydraulique multiple incluant des distributeurs conformes à l'invention; et
  • la figure 8 est une vue à plus grande échelle d'une partie du distributeur agencé en vue de son incorporation dans le circuit de la figure 7.
The invention will be better understood on reading the following detailed description of a preferred embodiment given solely by way of purely illustrative example. In this description, reference is made to the appended drawings in which:
  • Figure 1 is a sectional view of a hydraulic distributor arranged in accordance with the invention, the drawer of said distributor being disposed in neutral or inactive position;
  • Figure 2 is a sectional view of an alternative embodiment of the dispenser of Figure 1;
  • Figures 3 and 4 are sectional views of the dispenser of Figure 1 showing it respectively in two other different functional positions;
  • Figure 5 is a sectional view of yet another variant of a hydraulic distributor arranged according to the invention;
  • FIG. 6 is a diagram illustrating an example of the constitution of a multiple hydraulic control circuit including distributors according to the invention;
  • FIG. 7 is a diagram illustrating another example of the constitution of a multiple hydraulic control circuit including distributors according to the invention; and
  • FIG. 8 is a view on a larger scale of a part of the distributor arranged for incorporation into the circuit of FIG. 7.

En se référant tout d'abord à la figure 1, le distributeur qui y est représenté comporte un corps 1 muni d'un orifice P d'admission du fluide sous pression (constitué sous forme d'un canal 2 traversant le corps 1 transversalement au plan du dessin et débouchant sur les deux faces principales dudit corps servant d'appui lors de l'empilage côte-à-côte et l'un contre l'autre de plusieurs distributeurs), d'au moins un orifice T (constitué sous forme d'un canal traversant le corps 1 transversalement au plan du dessin et débouchant sur les deux faces principales dudit corps) de retour du fluide vers un réservoir (non représenté), de deux orifices A, B de raccordement à un appareil ou composant hydraulique (non représenté), et un tiroir 4 apte à coulisser dans un alésage 5 du corps 1 ; l'alésage 5 traverse longitudinalement le corps 1 et débouche sur deux faces opposées, ou faces d'extrémités 6, 7 de celui-ci. De façon classique, le corps 1 et le tiroir 4 comportent des passages et/ou des canalisations et/ou des gorges agencés de manière à coopérer en vue d'établir les connexions ou les fermetures souhaitées des différents orifices du corps du distributeur selon la position occupée par le tiroir. Les agencements spécifiques à l'invention de ces passages et/ou canalisations et/ou gorges seront indiqués plus loin.Referring firstly to FIG. 1, the distributor which is represented therein comprises a body 1 provided with an orifice P for admission of the pressurized fluid (constituted in the form of a channel 2 passing through the body 1 transversely to the plane of the drawing and opening onto the two main faces of said body serving as support during stacking side by side and one against the other of several distributors), of at least one orifice T (formed in the form a channel passing through the body 1 transversely to the plane of the drawing and emerging on the two main faces of said body) for the return of the fluid to a reservoir (not shown), two orifices A, B for connection to a hydraulic device or component ( not shown), and a drawer 4 capable of sliding in a bore 5 of the body 1; the bore 5 passes longitudinally through the body 1 and opens onto two opposite faces, or end faces 6, 7 thereof. Conventionally, the body 1 and the drawer 4 have passages and / or pipes and / or grooves arranged so as to cooperate with a view to establishing the desired connections or closings of the various orifices of the body of the dispenser according to the position. occupied by the drawer. The arrangements specific to the invention of these passages and / or pipes and / or grooves will be indicated later.

En outre, le corps 1 comporte encore un autre canal transversal 8 s'étendant entre les faces principales du corps et combiné avec au moins un sélecteur de pression permettant de transmettre, dans le canal 18 en aval du distributeur, la plus forte (pression "load sensing" ou pression LS) des deux pressions constituée respectivement par la pression en amont du distributeur et une pression de travail du distributeur. A chaque extrémité, le canal 8 débouche dans une cavité, creusée dans la face principale correspondante du corps (une cavité 9 est visible sur la figure 1). Le positionnement des cavités sur les faces principales est tel que, lors de l'empilage de deux distributeurs face contre face, la cavité 9 prévue sur une face principale de l'un et la cavité prévue sur la face principale coopérante de l'autre coopèrent pour constituer une chambre dans laquelle est abrité un joint d'étanchéité (non montré), ce grâce à quoi ledit canal 8 traverse de part en part le bloc de commande constitué par un empilement de plusieurs distributeurs quel que soit le nombre de ces derniers. Le principe du fonctionnement général d'un tel sélecteur de pression la plus élevée est bien connue de l'Homme de l'Art et ne sera pas reprise ici.In addition, the body 1 comprises yet another transverse channel 8 extending between the main faces of the body and combined with at least one pressure selector making it possible to transmit, in the channel 18 downstream of the distributor, the highest (pressure " load sensing "or pressure LS) of the two pressures constituted respectively by the pressure upstream of the distributor and a working pressure of the distributor. At each end, the channel 8 opens into a cavity, hollowed out in the corresponding main face of the body (a cavity 9 is visible in Figure 1). The positioning of the cavities on the main faces is such that, when stacking two distributors face to face, the cavity 9 provided on a main face of one and the cavity provided on the main cooperating face of the other cooperate to constitute a chamber in which is housed a seal (not shown), whereby said channel 8 passes right through the control block consisting of a stack of several distributors regardless of the number of these. The principle of the general operation of such a highest pressure selector is well known to those skilled in the art and will not be repeated here.

Le canal 2 raccordé à l'orifice d'admission P débouche dans l'alésage 5 du corps dans une chambre d'admission 10 de celui-ci, à proximité de laquelle une autre chambre 11 communique, par un passage 12, avec un logement 13 dans lequel est monté à libre coulissement étanche un plongeur 14. Le passage 12 débouche dans le logement 13 à une extrémité de celui-ci (correspondant à une face d'extrémité du plongeur 14), tandis qu'à son extrémité opposée le logement 13 débouche dans une cavité 15 dans laquelle peut se déplacer la tête 16 du plongeur 14. La tête 16, élargie par rapport au corps du plongeur, prend appui sur un épaulement formé au débouché du logement 13 dans la cavité 15 pour retenir le plongeur 14. Un ressort 17 peut être prévu dans la cavité 15 pour repousser le plongeur 14 contre ledit épaulement de manière à fixer sa position en l'absence de pressions. Le canal 8 précité est en communication avec la cavité 15, de telle sorte que la pression règnant dans le canal 8 soit également présente dans la cavité 15 et s'exerce alors sur l'extrémité correspondante du plongeur 14.The channel 2 connected to the intake orifice P opens into the bore 5 of the body in an intake chamber 10 thereof, near which another chamber 11 communicates, through a passage 12, with a housing 13 in which a plunger 14 is mounted in free sliding movement. The passage 12 opens into the housing 13 at one end thereof (corresponding to an end face of the plunger 14), while at its opposite end the housing 13 opens into a cavity 15 in which the head 16 of the plunger 14 can move. The head 16, enlarged relative to the body of the plunger, bears on a shoulder formed at the outlet of the housing 13 in the cavity 15 to retain the plunger 14. A spring 17 may be provided in the cavity 15 to push the plunger 14 against said shoulder so as to fix its position in the absence of pressure. The aforementioned channel 8 is in communication with the cavity 15, so that the pressure prevailing in the channel 8 is also present in the cavity 15 and is then exerted on the corresponding end of the plunger 14.

En outre, le plongeur 14 est traversé par un canal axial 18 débouchant d'un côté dans sa face d'extrémité en regard du passage 12 et de l'autre côté dans un canal diamétral 19 traversant le plongeur 14 et disposé de manière à être obturé par la paroi du logement 13 lorsque le plongeur 14 est dans la position de repos imposée par le ressort 17 (montré à la figure 1) ou dans une position non complètement relevée comme cela apparaîtra plus loin.In addition, the plunger 14 is crossed by an axial channel 18 opening on one side in its end face opposite the passage 12 and on the other side in a diametral channel 19 passing through the plunger 14 and arranged so as to be closed by the wall of the housing 13 when the plunger 14 is in the rest position imposed by the spring 17 (shown in Figure 1) or in a position not fully raised as will appear below.

La portion du tiroir 4 qui s'étend, en position neutre, entre les chambres 10 et 11 en les isolant l'une de l'autre est munie d'encoches de progressivité 20 destinées à assurer un écoulement contrôlé du fluide hydraulique dans le sens approprié lorsque le tiroir est déplacé dans un sens ou dans l'autre.The portion of the drawer 4 which extends, in the neutral position, between the chambers 10 and 11 by isolating them from one another is provided with progressivity notches 20 intended to ensure a controlled flow of the hydraulic fluid in the direction suitable when the drawer is moved in one direction or the other.

A partir du logement 13 précité s'étendent par exemple dans deux directions approximativement diamétralement opposées, deux conduits 21 dans chacun desquels est disposé si nécessaire un clapet anti-retour 22, les deux conduits 21 débouchant dans l'alésage 5 dans deux chambres respectives 23.From the aforementioned housing 13 extend for example in two approximately diametrically opposite directions, two conduits 21 in each of which is arranged if necessary a non-return valve 22, the two conduits 21 opening into the bore 5 in two respective chambers 23 .

Bien entendu, d'autres dispositions sont possibles dans ce contexte. A titre d'exemple, la figure 2 montre une variante selon laquelle un seul conduit 21 est prévu à partir du logement 13, avec un seul clapet anti-retour 22 au-delà duquel le conduit 21 se scinde en deux branches 21a, 21b, rejoignant respectivement les deux chambres 23.Of course, other arrangements are possible in this context. By way of example, FIG. 2 shows a variant according to which a single duct 21 is provided from the housing 13, with a single non-return valve 22 beyond which the duct 21 splits into two branches 21 a , 21 b , joining the two chambers 23 respectively.

A proximité des chambres 23, deux chambres de distribution respectives 24 de l'alésage 5 sont réunies, par des conduits 25, aux orifices de travail ou orifices de départ respectifs A et B.Near the chambers 23, two respective distribution chambers 24 of the bore 5 are joined together, by conduits 25, to the respective working or outlet orifices A and B.

Enfin, au-delà des chambres de distribution 24, respectivement deux chambres de retour 26 de l'alésage 5 sont raccordées, par des conduits 27, au canal de retour 3 débouchant sur l'orifice de retour T.Finally, beyond the distribution chambers 24, respectively two return chambers 26 of the bore 5 are connected, by conduits 27, to the return channel 3 opening onto the return orifice T.

Le fonctionnement du distributeur qui vient d'être décrit est le suivant.The operation of the dispenser which has just been described is as follows.

On supposera, pour cette explication, que le distributeur fait partie d'un bloc de commande multiple constitué par un empilement, face contre face, de plusieurs distributeurs identiques (un exemple de réalisation sera donné plus loin), dans lequel les orifices P, T et 9 prévus sur les faces principales communiquent les uns avec les autres ; en particulier, les canaux 8 constituent une ligne de transmission de la pression la plus élevée (ligne "load sensing" ou ligne LS) qui est raccordée à une entrée de commande d'une pompe à débit variable (non montrée) dont la sortie sous pression est raccordée aux orifices P.It will be assumed, for this explanation, that the distributor is part of a multiple control block constituted by a stack, face to face, of several identical distributors (an exemplary embodiment will be given below), in which the orifices P, T and 9 provided on the main faces communicate with each other; in particular, the channels 8 constitute a line for transmitting the highest pressure (“load sensing” line or LS line) which is connected to a control input of a variable flow pump (not shown), the output of which pressure is connected to ports P.

Le tiroir 4 étant en position neutre comme montré à la figure 1, toutes les chambres de l'alésage 5 sont isolées les unes des autres et aucun fluide ne s'écoule entre les orifices P, T, A et B. Le plongeur 14 est alors repoussé, par le ressort 17, en position d'appui sur sa tête, obturant les conduits 21, quelles que soient les pressions respectives règnant dans le passage 12 et la cavité 15 (pression LS).The slide 4 being in the neutral position as shown in FIG. 1, all the chambers of the bore 5 are isolated from each other and no fluid flows between the orifices P, T, A and B. The plunger 14 is then pushed back, by the spring 17, in the support position on its head, closing the conduits 21, whatever the respective pressures prevailing in the passage 12 and the cavity 15 (pressure LS).

Lorsque le tiroir est déplacé progressivement (par exemple vers la gauche, Fig. 3), le fluide hydraulique provenant de l'orifice P s'écoule, avec une chute de pression, par les encoches de progressivité 20 dans le passage 12 dans lequel la pression croît progressivement. Tant que la force due à la pression règnant dans le passage 12, s'exerçant sur la face inférieure du plongeur 14, reste inférieure à la somme de la force de tarage du ressort 17 et de la force dûe à la pression LS dans la cavité 15 qui s'exercent sur la face supérieure du plongeur 14, le plongeur 14 demeure dans la même position. Dès que la pression dans le passage 12 devient supérieure à la pression s'exerçant sur l'autre face du plongeur (tarage du ressort et pression LS), le plongeur commence à se déplacer (vers le haut sur le dessin) comme représenté à la figure 3, pour venir dans une nouvelle position d'équilibre dans laquelle la pression dans le passage 12 est égale à la pression LS augmentée de l'effort du ressort de tarage. Le plongeur dégage alors partiellement l'entrée du conduit 21 et le fluide s'écoule par ce chemin en subissant une chute de pression constante quel que soit le débit et régulée par l'écart entre la pression d'admission et la pression LS. Le clapet anti-retour 22 (celui situé à droite sur la figure 3 dans l'exemple considéré) s'ouvre et l'écoulement de fluide est acheminé vers l'orifice B. Dans ce contexte, le plongeur 14 se comporte comme un clapet (ou balance) de régulation de pression traditionnel.When the slide is moved gradually (for example to the left, Fig. 3), the hydraulic fluid coming from the orifice P flows, with a pressure drop, through the progressivity notches 20 in the passage 12 in which the pressure gradually increases. As long as the force due to the pressure prevailing in the passage 12, acting on the underside of the plunger 14, remains less than the sum of the setting force of the spring 17 and the force due to the pressure LS in the cavity 15 who are exerted on the upper face of the plunger 14, the plunger 14 remains in the same position. As soon as the pressure in passage 12 becomes greater than the pressure exerted on the other face of the plunger (spring setting and pressure LS), the plunger begins to move (upwards in the drawing) as shown in the Figure 3, to come into a new equilibrium position in which the pressure in the passage 12 is equal to the pressure LS increased by the force of the calibration spring. The plunger then partially clears the inlet of the conduit 21 and the fluid flows by this path while undergoing a constant pressure drop whatever the flow rate and regulated by the difference between the intake pressure and the LS pressure. The non-return valve 22 (the one located on the right in FIG. 3 in the example considered) opens and the fluid flow is routed towards the orifice B. In this context, the plunger 14 behaves like a valve. (or balance) of traditional pressure regulation.

Si le tiroir 4 est déplacé et si la pression LS dans la cavité 15 le permet (c'est-à-dire si la pression LS est inférieure à la pression maximale dans la chambre 12), la pression dans la chambre 12 devient telle que le plongeur 14 se soulève au maximum, dégageant au maximum l'entrée du conduit 21, tandis que le canal 19 du plongeur vient à déboucher dans la cavité 15. Du fluide du passage 12 s'écoule alors, par les canaux 18 et 19, dans la cavité 15 et, par là, dans le canal 8 : le distributeur considéré impose ainsi sa pression de commande en tant que pression LS. Dans ce contexte, le plongeur 14 se comporte comme sélecteur de pression la plus élevée dans la ligne de commande LS de la pompe.If the slide 4 is moved and if the pressure LS in the cavity 15 allows it (that is to say if the pressure LS is lower than the maximum pressure in the chamber 12), the pressure in the chamber 12 becomes such that the plunger 14 lifts up as far as possible, clearing the inlet of the duct 21 as much as possible, while the channel 19 of the plunger comes out into the cavity 15. Fluid from the passage 12 then flows, through the channels 18 and 19, in the cavity 15 and, thereby, in the channel 8: the distributor considered thus imposes its control pressure as LS pressure. In this context, the plunger 14 behaves as the highest pressure selector in the control line LS of the pump.

L'intérêt du distributeur agencé conformément à l'invention tient à la fois à la simplification structurelle qu'il représente (le même plongeur sert à la fois de compensateur de pression et de sélecteur de pression de la ligne LS, alors que deux éléments distincts, correspondant à deux circuits hydrauliques distincts, étaient employés jusqu'à présent) et à la plus grande précision de commande de la pompe qu'il entraîne : en effet, dans les circuits antérieurs, la pression LS était prélevée sur la pression de travail proprement dite ou pression de charge (par exemple au niveau des orifices de départ) avec les inconvénients exposés au début de la présente description, tandis que, dans le distributeur agencé selon l'invention, la ligne LS est alimentée par la pression la plus élevée provenant directement de la pompe et une fuite éventuelle dans la ligne LS n'a plus d'influence sur la charge (notamment n'est plus susceptible de provoquer une descente de la charge).The interest of the distributor arranged in accordance with the invention is due both to the structural simplification which it represents (the same plunger serves both as pressure compensator and pressure selector for the LS line, while two separate elements , correspondent two separate hydraulic circuits, have been used up to now) and the greater control accuracy of the pump that it drives: in fact, in the previous circuits, the pressure LS was taken from the working pressure itself or charge pressure (for example at the level of the outlets) with the drawbacks exposed at the beginning of this description, while, in the distributor arranged according to the invention, the line LS is supplied by the highest pressure coming directly from the pump and a possible leak in the LS line no longer influences the load (in particular is no longer likely to cause the load to drop).

En outre, le tiroir est de conception simple, sans canaux intérieurs, et sa fabrication est rendue plus aisée et moins coûteuse.In addition, the drawer is simple in design, without internal channels, and its manufacture is made easier and less expensive.

Enfin, un distributeur agencé selon l'invention permet de conserver au circuit hydraulique dans lequel il est inclus l'avantage d'un fonctionnement à division de débit que ne peut procurer le seul système "load sensing", c'est-à-dire que dans un circuit saturé les vitesses de tous les récepteurs sont diminuées proportionnellement aux débits respectifs dans ces récepteurs et il y a donc ralentissement ou immobilisation du récepteur ayant la charge la plus forte.Finally, a distributor arranged according to the invention makes it possible to keep the hydraulic circuit in which it is included the advantage of a flow division operation that cannot be obtained by the only "load sensing" system, that is to say that in a saturated circuit the speeds of all the receivers are reduced in proportion to the respective bit rates in these receivers and there is therefore slowing down or immobilization of the receiver having the highest load.

La figure 5 montre une variante de réalisation du distributeur hydraulique conforme à l'invention, dans lequel le circuit de compensation de pression et de sélection de la pression la plus élevée est dédoublé respectivement en correspondance avec les deux circuits de départ A et B. Les mêmes références numériques ont été utilisées pour désigner les mêmes organes que pour le distributeur de la fig. 1 ; les deux cavités 15 sont réunies à un seul et unique canal LS8. Le fonctionnement reste identique à ce qui a été décrit précédemment, à ceci près qu'un seul plongeur est en fonction selon le sens de déplacement du tiroir 4 et selon que le départ s'effectue par l'orifice A ou l'orifice B.FIG. 5 shows an alternative embodiment of the hydraulic distributor in accordance with the invention, in which the pressure compensation and highest pressure selection circuit is split respectively in correspondence with the two starting circuits A and B. same reference numerals have been used to designate the same members as for the dispenser of FIG. 1; the two cavities 15 are joined to a single LS8 channel. The operation remains identical to what has been described above, except that a single plunger is in operation according to the direction of movement of the slide 4 and depending on whether the departure is made through the orifice A or the orifice B.

La figure 6 est un schéma illustrant un exemple d'un circuit hydraulique de commande multiple faisant appel à un bloc de commande hydraulique multiple utilisant un empilement de plusieurs distributeurs conformes à l'invention.FIG. 6 is a diagram illustrating an example of a multiple control hydraulic circuit using a multiple hydraulic control block using a stack of several distributors according to the invention.

Le bloc de commande hydraulique comprend un empilement de plusieurs distributeurs D₁, D₂..., Dn, dont les orifices d'admission P, de retour T et de commande de pompe LS sont tous réunis entre eux par la simple juxtaposition étanche des faces principales des corps des distributeurs, d'une façon en soi bien connue de l'Homme de l'Art. Par exemple, un élément terminal aveugle 28 est monté à une extrémité de l'empilement pour obturer les conduits P, T et LS respectifs de l'empilement ; cet élément terminal pourrait pour certaines applications, être pourvu d'un dispositif réducteur de pression (non montré).The hydraulic control unit comprises a stack of several distributors D₁, D₂ ..., D n , the inlet ports P, return T and pump control LS of which are all joined together by the simple tight juxtaposition of the faces main bodies of distributors, in a manner well known to those skilled in the art. For example, a blind terminal element 28 is mounted at one end of the stack to close the respective conduits P, T and LS of the stack; this terminal element could for certain applications be provided with a pressure reducing device (not shown).

Un élément d'entrée 29 est transparent pour la ligne d'admission P qui est reliée à la sortie sous pression d'une source de fluide sous pression à débit variable -qui peut être par exemple une pompe à débit variable Pp comme représenté à la figure 6 ou bien encore une pompe à débit fixe avec valve à centre ouvert- et pour la ligne de retour T qui est reliée à un réservoir R.An inlet element 29 is transparent for the inlet line P which is connected to the outlet under pressure from a source of pressurized fluid with variable flow rate -which may for example be a variable flow pump P p as shown in Figure 6 or even a fixed flow pump with open center valve - and for the return line T which is connected to a tank R.

Par ailleurs, la ligne LS est reliée, dans l'élément d'entrée 29, à la ligne de retour T à travers un premier régulateur de débit tel qu'un gicleur ou étrangleur 30 destiné à permettre la décompression de l'ensemble du dispositif lorsque le débit est nul (c'est-à-dire lorsque tous les distributeurs étant en position neutre).Furthermore, the line LS is connected, in the input element 29, to the return line T through a first flow regulator such as a nozzle or throttle 30 intended to allow the decompression of the entire device when the flow is zero (i.e. when all the distributors are in neutral position).

Enfin, la pression LSp de commande par détection de charge destinée à la pompe est prélevée sur la ligne LS, en amont du premier gicleur 30, à travers un second gicleur 31. Ce gicleur 31 a pour fonction de recréer une chute de pression aux bornes du plongeur 14 de chacun des distributeurs du bloc. Dans l'exemple considéré, un gicleur 31 unique est placé dans l'élément d'entrée 29. Un clapet limiteur 32, destiné à limiter la valeur maximale de la pression de commande de détection de charge lorsque la pompe fonctionne à son débit maximum, est interposé entre la ligne LSp et la ligne de retour T.Finally, the charge detection control pressure LS p intended for the pump is taken from the line LS, upstream of the first nozzle 30, through a second nozzle 31. This nozzle 31 has the function of recreating a pressure drop at the terminals of the plunger 14 of each of the distributors of the block. In the example considered, a single nozzle 31 is placed in the inlet element 29. A limiting valve 32, intended to limit the maximum value of the charge detection control pressure when the pump is operating at its maximum flow rate, is interposed between the line LS p and the return line T.

La figure 7 est un schéma illustre un autre exemple d'un circuit hydraulique de commande multiple faisant appel à un bloc de commande hydraulique multiple utilisant un empilement de plusieurs distributeurs agencés selon l'invention. Cet agencement se distingue de celui de la figure 6 par le fait qu'un gicleur 31 est ici prévu dans chacun des distributeurs, en lieu et place du gicleur 31 unique précédemment logé dans l'élément d'entrée 29.FIG. 7 is a diagram illustrating another example of a hydraulic multiple control circuit using a multiple hydraulic control block using a stack of several distributors arranged according to the invention. This arrangement differs from that of FIG. 6 by the fact that a nozzle 31 is here provided in each of the distributors, in place of the single nozzle 31 previously housed in the input element 29.

A la figure 7, l'élément d'entrée dépourvu du gicleur est désigné par la référence 29', tandis que les distributeurs équipés chacun d'un gicleur 31 sont respectivement désignés D'₁, D'₂,..., D'n. Dans chaque bloc D'₁, D'₂,..., D'n une représentation très simplifiée du distributeur est donnée, accompagnée des références numériques utilisées à la figure 1, de manière à montrer la situation du gicleur 31. Le gicleur 31 est interposé entre le canal 8 de ligne de détection de charge et la chambre de distribution 11 ; ce gicleur est rendu fonctionnel lorsqu'une communication est établie entre le passage 12 et le canal 8 par le déplacement du plongeur 14 et il est agencé pour créer une perte de charge inférieure au tarage du ressort du plongeur du distributeur qu'il équipe.In FIG. 7, the inlet element without the nozzle is designated by the reference 29 ', while the distributors each equipped with a nozzle 31 are respectively designated D'respectivement, D'₂, ..., D' n . In each block D'₁, D'₂, ..., D ' n a very simplified representation of the distributor is given, accompanied by the numerical references used in FIG. 1, so as to show the situation of the nozzle 31. The nozzle 31 is interposed between the load detection line channel 8 and the distribution chamber 11; this nozzle is made functional when a communication is established between the passage 12 and the channel 8 by the displacement of the plunger 14 and it is arranged to create a pressure drop lower than the setting of the spring of the plunger of the distributor which it equips.

La figure 8 montre un exemple d'implantation du gicleur 31. Sur cette vue à échelle agrandie montrant plus particulièrement le plongeur 14, le gicleur 31 est logé dans la partie supérieure, étroite du canal axial 18 percé dans le plongeur et reliant le canal diamétral 19 percé dans le plongeur avec le passage 12. L'adaptation du distributeur pour ce type de circuit est donc facile et peu coûteuse à réaliser.FIG. 8 shows an example of installation of the nozzle 31. In this view on an enlarged scale showing more particularly the plunger 14, the nozzle 31 is housed in the upper, narrow part of the axial channel 18 drilled in the plunger and connecting the diametral channel 19 drilled in the plunger with the passage 12. The adaptation of the distributor for this type of circuit is therefore easy and inexpensive to carry out.

Comme il va de soi et comme il résulte d'ailleurs déjà de ce qui précède, l'invention ne se limite nullement à ceux de ses modes d'application et de réalisation qui ont été plus particulièrement envisagés.As goes without saying and as it already follows from the above, the invention is in no way limited to those of its modes of application and embodiments which have have been more particularly envisaged.

Claims (14)

  1. A pressure compensating hydraulic directional control valve comprising :
    - a valve body (1) ;
    - a slide (4) received in the body (1) to be capable of being displaced longitudinally therein for selectively transmitting a pressurized hydraulic fluid to working orifices (A, B) provided in the body from a pressurized hydraulic fluid admission orifice (P) ;
    - a fluide passage (12, 21) in said body (1) for connecting a distribution chamber (11) to the working orifices (A, B), said distribution chamber (11) being associated with the slide (4) and being suitable for being connected selectively to the admission orifice (P) by the displaced slide (4) ;
    - a load sensing line channel (8) combined with highest pressure selecting means organized to establish in said channel the highest pressure selected from the pressure existing in said channel and the pressure of the pressurized fluid of the valve ; and
    - pressure compensating means placed in said fluid passage (12, 21) and responsive to the difference between the pressure of the fluid in the valve and the pressure existing in said channel (8) in order to generate a substantially fixed pressure drop in the pressurized fluid flowing towards the working orifices (A, B) ;
    characterized in that the pressure compensating means are combined with the highest pressure selecting means, and in that selective link means exist that are suitable for selectively establishing a link between the channel (8) and the passage (12) upstream from the pressure compensating means in such a manner that :
    . if the pressure in the channel (8) is greater than or equal to the pressure of the fluid in the passage (12) upstream from the pressure compensating means, no communication exists between said passage (12) upstream from the pressure compensating means and said channel (8), and the pressure in the channel (8) retains its value, or else
    . if the pressure in the channel (8) is less than the pressure of the fluid in the passage (12) upstream from the pressure compensating means, communication is established between said passage (12) upstream from the pressure compensating means and said channel (8), and the pressure in the channel (8) becomes the same as the pressure of the fluid in the passage (12) upstream from the pressure compensating means.
  2. A hydraulic valve according to claim 1, characterized in that the pressure compensating means combined with the highest pressure selecting means comprise :
    - a bore (13) provided in the body (1) and connected at one end to said passage (12) upstream from the pressure compensating means coming from the chamber (11) controlled by the slide (4) and at its other end to said load sensing line channel (8) ;
    - a moving control plunger (14) free to slide in said bore (13) in relation with pressures acting on opposite ends thereof ;
    - first shutter means disposed in said fluid passage (12, 21) and secured to said plunger ;
    - second shutter means disposed in a connection (18, 19) between said passage (12) upstream from the pressure compensating means and said channel and secured to said plunger, said plunger being suitable for occupying :
    . a first end position or "doubly-closed" position which it occupies in the absence of pressurized fluid, and in which the first and second shutter means are closed ;
    . a set of intermediate positions occupied when the pressurized fluid is present in the passage (A), the position of the plunger being determined by the difference between the pressure in the passage (A) and the pressure in the channel when the pressure in the channel is greater than the pressure in the passage, in which the second shutter means are kept closed and the first shutter means are opened to an extent suitable for causing a predetermined pressure drop in the flow of pressurized fluid ;
    . and a second end position or "doubly-open" position which is occupied when the pressure of the fluid in the passage (A) is greater than the pressure in the channel, in which the first shutter means are fully open and the second shutter means are also open, thereby establishing communication between said passage (A) and said channel.
  3. A hydraulic valve according to claim 2, characterized in that :
    - said passage (12) upstream from the pressure compensating means connected to the chamber (11) controlled by the slide (4) communicates with one end of the bore (13) ;
    - the portion (21) of said fluid passage connected to the working orifices (A, B) opens radially into the bore (13) ;
    - said first shutter means are constituted by said plunger (14) implemented in elongate form so that :
    . in its first end position, it fully closes said opening of the passage ;
    . in its set of intermediate positions, it partially closes said opening to create the predetermined pressure drop ;
    . and in its second end position, it completely opens said opening.
  4. A hydraulic valve according to claim 3, characterized in that said second shutter means are constituted by said plunger provided with an internal duct (18, 19) that opens out at one end into the face of the plunger which is subjected to the pressure of the fluid in the passage upstream from the pressure compensating means and that opens out at its other end radially into the vicinity of the other face of the plunger which is subjected to the pressure of the channel, in such a manner that :
    . when the plunger is in its first extreme position and in its set of intermediate positions, the radial outlet of said duct (19) is closed by the bore (13) ; and
    . when the plunger is in its second extreme position, the radial outlet of said duct (19) has moved out from the bore (13) and is in communication with said channel (8).
  5. A hydraulic valve according to anyone of claims 1 to 4, characterized in that the pressure compensating means and maximum pressure selecting means, combined together, are unique and are selectively connectable to one of the two working orifices.
  6. A hydraulic valve according to anyone of claims 1 to 4, characterized in that the pressure compensating means and maximum pressure selecting means, combined together, are two-fold, each associated with a respective one of the two working orifices.
  7. A hydraulic valve according to anyone of claims 1 to 6, characterized in that at least one check valve is provided in said fluid passage, between the pressure compensating means and at least one working orifice.
  8. A hydraulic valve according to claim 7, characterized in that it includes a single check valve in said fluid passage, between the pressure compensating means and one working orifice.
  9. A hydraulic valve according to claim 7, characterized in that it includes two check valves in said fluid passage, between the pressure compensating means and the two working orifices, respectively.
  10. A hydraulic valve according to anyone of claims 2 to 9, characterized in that the pressure compensating means (14) combined with the highest pressure selecting means (14) further comprise resilient return means (17) acting on the moving plunger (14) in the same direction as the acting direction of the pressure in the channel (8).
  11. Multiple hydraulic control apparatus interposed between a variable flow rate source of pressurized fluid (Pp) and a tank (R) on one side and a plurality of hydraulic load members having to be respectively and selectively controlled from said source, characterized in that it comprises a side-by-side stack of :
    - a plurality of hydraulic directional control valves (D₁, D₂,..., Dn) according to anyone of claims 1 to 10 ;
    - an end element (28) ;
    - and an inlet element (29) which is transparent for the lines P and T of the stacked valves connected respectively to the pressurized outlet of the source (Pp) and to the tank (R), which includes a decompression flow rate regulator (30) interposed between a load sensing source control line (LS) from the stacked valves and the return line (T), and which includes a throttle (31) interposed between the load sensing source control line (LS) from the stacked valves and the control input of the source (Pp), said throttle (31) being arranged so as to generate a pressure loss across the terminals of the plunger in each valve.
  12. Multiple hydraulic control apparatus interposed between a variable flow rate pressurized fluid source (Pp) and a tank (R) on one side, and a plurality of hydraulic load members having to be respectively and selectively controlled from said source, characterized in that it comprises a side-by-side stack of :
    - a plurality of hydraulic directional control valves (D₁, D₂,..., Dn) according to anyone of claims 2 to 10, each valve including a throttle (31) interposed between the load sensing line channel (8) and the distribution chamber (11), said throttle (31) being made operative when communication is established between the passage (12) upstream from the pressure compensating means and the channel (8) and being arranged so as to generate a pressure loss across the terminals of the plunger of the valve ;
    - an end element (28) ;
    - and an inlet element (29) which is transparent for the lines P and T of the stacked valves connected respectively to the pressurized outlet of the source (Pp) and to the tank (R), and which includes a decompression flow rate regulator (30) interposed between a load sensing source control line (LS) from the stacked valves and the return line (T).
  13. Multiple hydraulic remote control apparatus according to claim 12, characterized in that the throttle (31) in each valve is housed in the connection (19) provided inside the plunger (14).
  14. Multiple hydraulic remote control apparatus according anyone of claims 11 to 13, characterized in that a circuit (32) for limiting the load sensing source control pressure is interposed between the control inlet of the source (Pp) and the return line (T) for limiting said control pressure when the source is providing its maximum pressure.
EP93400866A 1992-04-06 1993-04-02 Hydraulic maximum load and pressure compensating valve Expired - Lifetime EP0566449B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9204183A FR2689575B1 (en) 1992-04-06 1992-04-06 HYDRAULIC DISTRIBUTOR WITH PRESSURE COMPENSATION AND A MAXIMUM PRESSURE SELECTION FOR DRIVING A PUMP AND MULTIPLE HYDRAULIC CONTROL INCLUDING SUCH DISTRIBUTORS.
FR9204183 1992-04-06

Publications (2)

Publication Number Publication Date
EP0566449A1 EP0566449A1 (en) 1993-10-20
EP0566449B1 true EP0566449B1 (en) 1995-12-20

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EP93400866A Expired - Lifetime EP0566449B1 (en) 1992-04-06 1993-04-02 Hydraulic maximum load and pressure compensating valve

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US (1) US5305789A (en)
EP (1) EP0566449B1 (en)
JP (1) JP3531949B2 (en)
DE (1) DE69301052T2 (en)
FR (1) FR2689575B1 (en)

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Also Published As

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JP3531949B2 (en) 2004-05-31
FR2689575B1 (en) 1994-07-08
FR2689575A1 (en) 1993-10-08
DE69301052D1 (en) 1996-02-01
JPH0658305A (en) 1994-03-01
DE69301052T2 (en) 1996-08-08
EP0566449A1 (en) 1993-10-20
US5305789A (en) 1994-04-26

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