DE102018200825B3 - Control system for a hydraulic variable pump, pump set and vehicle with a pump set - Google Patents

Abstract

The present invention relates to a control system (1) for pressurizing at least one actuating cylinder of a variable displacement pump with a pressure port (2), a control cylinder port (3), a tank port (4), a first main stage 6) and a second main stage (7). Between the first main stage (6) and the second main stage (7), a connecting line (8) is arranged. The first main stage (6) connects the actuating cylinder connection (3) in a first switching position (A1) with the pressure port (2) and in a second switching position (A2) with the connecting line (8). The second main stage (7) connects the connecting line (8) in a first switching position (B1) to the pressure port (3) and in a second switching position (B2) to the tank port (4). The first or the second main stage (6, 7) is vorsteuerbar. A bypass line (9) connects the connecting line (8) to the actuating cylinder connection (3), wherein a logic element (10a) is arranged in the bypass line (9) which releases the bypass line (9) when a limiting pressure in the connecting line (8) above a limit pressure at the actuating cylinder connection (3). Furthermore, the invention relates to a pump unit and vehicle.

Description

The present invention relates to a control system for pressurizing at least one actuating cylinder of a hydraulic variable displacement pump with the features specified in the preamble of patent claim 1. A generic control system is from the EP 2 682 610 B1 known. Furthermore, the invention relates to a pump unit with a control system according to the invention and a vehicle with such a pump unit.

Such control systems regularly have a pressure connection, an actuating cylinder connection, a tank connection, a first main stage and a second main stage. Between the first main stage and the second main stage, a connecting line is arranged so that the first main stage and the second main stage are connected in series. The first main stage connects the actuating cylinder connection in a first switching position with the pressure port and in a second switching position, the connecting line with the actuating cylinder connection. The second main stage connects the connecting line in a first switching position to the pressure port and in a second switching position, the connecting line to the tank port. The first or the second main stage is vorsteubar via a pilot signal. For example, the precontrol can be a pressure precontrol based on a load pressure signal. The necessary signal pressure or the load pressure signal is tapped, for example, directly at a supplied with pressure hydraulic consumers. Alternatively, the signal pressure can be generated in a constant pressure operation via a proportional valve and so reported to the control system.

About these known control systems, at least one actuating cylinder of the variable displacement pump is pressurized, so that the variable displacement pump, for example, a swash plate axial piston pump, can be adjusted between a minimum funding and a maximum promotion. Such a pump unit with a variable displacement pump and a control system is marketed by the applicant, for example under the product name "V80M".

By means of such a control system, the pump pressure applied to the pressure connection and supplied by the variable displacement pump can be applied to the control cylinder connection depending on the load pressure, or the control cylinder connection can be relieved to the tank. Consequently, the actuating cylinder is controlled via a pressurization or relief of the adjustment of the delivery of the variable displacement. In other words, when a load pressure or pre-control signal is present, the first main stage and the second main stage are each switched to the second switching position, so that the actuating cylinder of the pump unit is relieved via the actuating cylinder connection to the tank. Correspondingly, when the pilot control signal is eliminated, the first and second main stages are each switched to the first switching position, so that the actuating cylinder is acted upon by pressure from the pressure port and the variable-displacement pump is adjusted to a minimum or stand-by pressure.

In these known control system, it can happen again and again that the variable displacement pump after a maximum pressure operation also after the elimination of the pilot control signal does not adjust to the stand-by pressure, but remains at maximum pressure. In the known control systems, designed for the pressure control main stage switches to the first switching position, thus blocking the other main stage. Under certain circumstances, this can also lead to an unwanted vibration behavior of the variable. This has the disadvantage that the variable displacement pump runs hot and can cause burns. On the other hand, so also the wear of the pump increases, which in turn reduces the life.

It is therefore an object of the present invention to show a control system for a hydraulic variable displacement pump, in which the variable adjustment after the elimination of the pilot signal reliably adjusted to the set stand-by pressure and therefore also does not tend to a vibration behavior.

The solution of the problem is achieved with the features of claim 1. Advantageous developments are described in the dependent claims.

The control system according to the invention is distinguished from the known control system in that a bridging line connects the connecting line with the actuating cylinder connection, wherein a logic element is arranged in the bypass line. According to the invention, the logic element releases the bypass line when a limiting pressure in the connecting line is above a limiting pressure at the actuating cylinder connection. This makes it possible that the pump remote main stage can feed directly into the actuating cylinder connection, if necessary, so that the actuating cylinder pressurized and the variable displacement can be adjusted to stand-by pressure. The limit pressure of the connecting line is to be understood as meaning the actual pressure in the connecting line plus the response pressure of the logic element. The limit pressure in the actuating cylinder connection is the actual pressure in the actuating cylinder connection. Thus, the pump remote main stage then feeds directly into the actuating cylinder connection, if the actual pressure in the Connecting line to the logic element caused by the differential pressure is above the actual applied to the actuating cylinder pressure.

The solution according to the invention is based on the recognition that the main stage designed for pressure regulation-for example the first main stage-blocks the controller based on the pilot signal-for example the second main stage. In this case, although the controller based on the pilot control signal responds, it can not feed pump pressure into the actuator cylinder connection since the (first) main stage designed for pressure control blocks the connecting line. As a result, the limiting pressure in the connecting line rises above the limit pressure in the actuating cylinder connection. According to the invention, the bridging line is now released via the logic element, so that the (second) main stage regulated according to the pilot signal feeds the pump pressure directly into the actuating cylinder connection. The variable displacement pump is effectively regulated to standby pressure by the increasing pressure in the actuator cylinder port.

Conveniently, the logic element is a check valve. As a result, a rapid response of the logic element can take place in the event of a blockade of the main stage regulated according to the pilot control signal, so that rapid injection into the actuating cylinder connection takes place.

Alternatively, it is expedient if the logic element is a spring-loaded check valve. Depending on requirements, the bridging line can be released with a certain and predefined pressure difference. For example, it can be prevented that the bridging line is unintentionally released at a short-term pressure peak.

Expediently, the first main stage or the second main stage has at least one electromagnet for the electro-proportional precontrol. In this case, the pilot signal is an electrical signal which, due to the corresponding energization of the electromagnet, switches the main stage having the electromagnet into the desired switching position.

Alternatively, it is advantageous if the control system has a load pressure signal connection, wherein the first main stage or the second main stage is pressure-controlled via the load pressure signal connection or is pressure controllable. In this case, the pilot signal is a load pressure signal.

It is advantageous if the second main stage is pressure-controlled via the load pressure signal connection and the pressure connection, wherein the pressure in the pressure connection acts in the direction of the first switching position and the pressure in the load pressure signal connection acts in the direction of the second switching position. Preferably, the second main stage has a spring element, wherein the spring element acts in the direction of the second switching position. Conveniently, the spring element is an adjustable spring element. Thus, the second main stage acts as a signal-pressure-dependent controller or LS controller. According to the invention, therefore, the second main stage, even with a blockage by the first main stage with a discharge of the signal pressure pump pressure via the logic element feed directly into the actuating cylinder connection.

Conveniently, the first main stage is pressure-controlled via the pressure connection and has a spring element, wherein the pressure in the pressure connection acts in the direction of the first switching position and the spring element acts in the direction of the second switching position. Preferably, the spring element is an adjustable spring element. Thus, the first main stage is a pressure or N controller.

Furthermore, the invention relates to a pump unit with a control system according to the invention and a hydraulic variable displacement pump with at least one actuating cylinder. The variable displacement pump is connected to the pressure connection of the control system and the actuating cylinder can be pressurized via the control cylinder connection. The invention further relates to a vehicle having such a pump unit, for example a forest vehicle, a municipal vehicle or a construction vehicle.

• 1 einen hydraulischen Schaltplan eines erfindungsgemäßen Pumpenaggregats mit einem erfindungsgemäßen Regelsystem;
• 2 einen hydraulischen Schaltplan eines erfindungsgemäßen Regelsystems gemäß einer ersten Ausführungsform; und
• 3 einen hydraulischen Schaltplan eines erfindungsgemäßen Regelsystem gemäß einer zweiten Ausführungsform.

The invention will be explained in more detail with reference to exemplary embodiments shown in the figures. Show here

• 1 a hydraulic circuit diagram of a pump assembly according to the invention with a control system according to the invention;
• 2 a hydraulic circuit diagram of a control system according to the invention according to a first embodiment; and
• 3 a hydraulic circuit diagram of a control system according to the invention according to a second embodiment.

1 shows a hydraulic circuit diagram of a pump unit according to the invention 100 with a hydraulic variable pump 109 and a rule system 1 , In the in 1 The embodiment shown corresponds to the control system 1 the control system 1 according to the first embodiment, as described below with respect to 2 is explained in more detail. Of course, the pump unit 100 alternatively, but also a rule system 1 according to the second embodiment, as shown in FIG 3 shown and will also be explained in more detail below, have.

The variable pump 109 has an actuating cylinder 101 on, the over a Stellzylinderleitung 104 with a corresponding actuating cylinder connection 3 of the control system 1 connected is. Furthermore, the variable displacement pump has a pressure line 105 on, which via a first pressure line branch 106 to a spring-loaded pressure actuator cylinder 102 connected. In addition, the pressure line opens 105 in a hydraulic consumer connection 103 , via which the corresponding hydraulic consumers at least indirectly to the pump unit 100 are connected.

From the first pressure line branch 106 branches a second pressure line branch 107 from. The second pressure line branch 107 is with a pressure connection 2 of the control system 1 connected. Depending on the position of the adjusting cylinder 101 and the pressure cylinder 102 the variable displacement pump is running 109 with maximum delivery or maximum pump pressure p _max or is on standby or standby p _SB governed. This is in 1 indicated by the corresponding arrows. Of course, corresponding intermediate positions are possible. Furthermore, the variable displacement pump 109 a tank line 108 on which among other things to a tank connection 4 of the control system 1 connected.

In the embodiment shown, the control system regulates 1 the delivery rate of the variable displacement pump 109 by means of a load pressure signal, which via a load pressure signal connection 5 to the control system 1 is reported. The load pressure signal may, for example, be a load pressure signal tapped on the connected hydraulic consumer, or, in the case of constant pressure operation, a load pressure signal generated via a proportional valve.

The control system 1 according to the first embodiment is in 2 shown in more detail. The control system 1 is an LSN control system and has a first main stage 6 and a second main stage 7 on. The first main stage 6 In this embodiment, the pump-closer and designed for pressure or N-control main stage. The second main stage 6 is therefore designed as a pump remote and based on a load pressure signal main stage. As shown, the first major level 6 and the second main stage 7 Both proportional 3/3-way valves, whereby the use of 3/2-way valves is possible.

Between the first main stage 6 and the second main stage 7 is a connection line 8th arranged, which, depending on the switching position of the first main stage 6 and the second main stage 7 for pressurization or discharge to the tank of the adjusting cylinder line 104 serves. The first main level connects to this 6 in a first switching position A1 the pressure connection 2 with the actuating cylinder connection 3 , wherein the connecting line 8th Is blocked. In a second switching position A2 is the pressure connection 2 locked and the connection line 8th is via the actuating cylinder connection 3 with the actuating cylinder line 104 connected. In an intermediate position A3 between the first switching position A1 and the second switching position A2 there is a restricted connection between the pressure connection 2 , the actuating cylinder connection 3 and the connection line 8th , To regulate the first main stage 6 branches from the pressure connection 2 a first pressure message line 13 from which the pump pressure to first main stage 6 in the direction of the first switching position A1 acting reports. In addition, the first major stage points 6 one in the direction of the second switching position A2 acting and preferably adjustable spring element 12 on.

Accordingly, the second main stage connects 7 in a first switching position B1 the pressure connection 2 with the connection line 8th , where the tank connection 4 Is blocked. In a second switching position B2 is the connection line 8th with tank connection 4 connected, the pressure connection 2 Is blocked. In an intermediate position B3 between the first switching position B1 and the second switching position B2 there is a restricted connection between the pressure connection 2 , the tank connection 4 and the connection line 8th , To regulate the second main stage 7 branches from the pressure connection 2 a second pressure message line 14 from which the pump pressure to the second main stage 7 in the direction of the first switching position B1 acting reports. Via a load pressure signal line 15 this will be at the load pressure signal port 5 applied load pressure signal to the second main stage 7 in the direction of the second switching position B2 acting reports. Further, the second main stage 7 a preferably adjustable spring element 11 on, which also in the direction of the second switching position B2 acts.

As in 2 shown branches off the connecting line 8th a bridging line 9 with a logic element 10a from. The bypass line 9 flows, bypassing the first main stage 6 in the actuating cylinder connection 3 , The logic element 10a is a check valve in this first embodiment 10a , The check valve 10a gives the bypass line 9 free, if a limiting pressure in the connecting line 8th above one on the actuating cylinder connection 3 adjacent limit pressure is. Thus, the second main stage feeds 7 then directly into the actuating cylinder connection 3 and therefore the actuating cylinder line 104 one when the actual pressure in the connection line 8th around the through the check valve 10a conditional differential pressure over the actual on the actuator cylinder connection 3 applied pressure is. It is conceivable that this differential pressure, for example, 0.5 bar, so a fast Response of the check valve 10a and thus a rapid release of the bypass line 9 he follows.

The embodiment according to 3 essentially corresponds to the embodiment according to 2 , where the control system 1 here a spring-loaded check valve 10b as a logic element. As a result, a higher differential pressure of, for example, up to 10 bar can be achieved, so that the bypass line 9 is not released at a short-term pressure peak.

The following describes an operating situation in which a blockage in the control system 1 due to the bridging line 9 not to permanent lingering of the variable displacement pump 109 to maximum pressure p _max and a swing of the variable displacement pump 109 leads.

As long as the variable pump 109 not yet at maximum pressure p _max is the first major stage 6 in the second switching position A2 and is the second major level 7 in the second switching position B2 , The rising pressure in the pressure line 105 leads to a return stroke in the actuating cylinder 101 , so that hydraulic fluid via the actuating cylinder line 104 into the control system 1 flows and here over the tank connection 4 and the tank line 108 is relieved to the tank.

As soon as the variable pump 109 due to a corresponding load pressure signal in the load pressure signal line 15 the maximum pressure p _max achieved, becomes the first major stage 6 via the intermediate switching position A3 in the first switching position A1 connected. This is an injection of pump pressure via the connecting line 8th through the second main stage 7 only to a very limited extent (if the first main level 6 in the switching position A3 is) or not possible (if the first main level 6 in the switching position A1 is).

Now if the load pressure signal in load pressure signal line 15 is relieved to the tank - for example, because a user releases the joystick of a controller - becomes the second main stage 7 via the intermediate switching position B3 in the first switching position B1 emotional. Due to the blockade in the first main stage 6 is therefore the attractive regulation of the second main stage 7 ineffective. The pressure in the connecting pipe 8th rises, so that this quickly over the Stellzylinderanschluss 3 is applied pressure. As soon as the pressure in the connecting line 8th around the differential pressure of the logic element 10a . 10b above that on the actuating cylinder connection 3 lying pressure is the logic element 10a . 10b the bypass line 9 free. About the second main stage 9 is then directly hydraulic fluid, bypassing the first main stage 6 via the actuating cylinder connection 3 in the adjusting cylinder line 104 fed. As a result, a stroke of the actuating cylinder 101 reached and the variable pump is at standby pressure p _SB adjusted. Thus, the first main level 6 in turn about the first intermediate switching position A3 in the second switching position A2 switched and the logic element 10a . 10b closes the bypass line 9 again.

LIST OF REFERENCE NUMBERS

1

control system

2

pressure connection

3

Actuating cylinder connection

4

tank connection

5

Load pressure signal connection

6

first main stage / N controller

7

second main stage / LS controller

8th

connecting line

9

bypass line

10a

Logic element / check valve

10b

Logic element / spring-loaded check valve

11

spring element

12

spring element

13

first pressure signaling line

14

second pressure signaling line

15

Load pressure signal line

100

pump unit

101

actuating cylinder

102

Pressure adjusting cylinders

103

Hydraulic actuator port

104

Actuating cylinder line

105

pressure line

106

first pressure line branch

107

second pressure line branch

108

tank line

109

variable

A1

first switching position of the first main stage

A2

second switching position of the first main stage

A3

Intermediate position of the first main stage

B1

first switching position of the second main stage

B2

second switching position of the second main stage

B3

Intermediate position of the second main stage

p _max

maximum pump pressure / maximum flow rate

p _SB

Standby pressure / standby capacity

Claims (10)

Control system (1) for pressurizing at least one actuating cylinder (101) of a hydraulic variable displacement pump (109) with a pressure port (2), a control cylinder port (3), a tank port (4), a first main stage (6) and a second main stage (7 ), wherein a connecting line (8) between the first main stage (6) and the second main stage (7) is arranged, wherein the first main stage (6) the actuating cylinder terminal (3) in a first switching position (A1) with the pressure port (2) connects and in a second switching position (A2) connecting the connecting line (8) with the actuating cylinder connection (3), wherein the second main stage (7) connects the connecting line (8) in a first switching position (B1) with the pressure port (3) and in a second switching position (B2), the connecting line 8) connects to the tank connection (4), wherein the first main stage (6) or the second main stage (7) is vorsteuerbar via a pilot signal, characterized in that s a bridging line (9) connecting the connecting line (8) with the actuating cylinder connection (3), wherein a logic element (10a, 10b) in the bypass line (9) is arranged, wherein the logic element (10a, 10b), the bypass line (9) releases when a limit pressure in the connecting line (8) is above a limit pressure at the actuating cylinder connection (3). Control system (1) to Claim 1 , characterized in that the logic element (10a) is a check valve. Control system (1) to Claim 1 , characterized in that the logic element (10b) is a spring-loaded check valve. Control system (1) after one of the previous Claims 1 to 3 , characterized in that the first main stage (6) or the second main stage (7) has at least one electromagnet for the electro-proportional pilot control. Control system (1) after one of the previous Claims 1 to 3 , characterized in that the control system (1) has a load pressure signal port (5), wherein the first main stage (6) or the second main stage (7) via the load pressure signal port (5) is pressure controlled. Control system (1) to Claim 5 , characterized in that the second main stage (7) via the load pressure signal port (5) and the pressure port (2) is pressure controlled, wherein the pressure in the pressure port (2) in the direction of the first switching position (B1) acts and the pressure in the load pressure signal port (5 ) acts in the direction of the second switching position (B2). Control system (1) to Claim 6 , characterized in that the second main stage (7) has a preferably adjustable spring element (11), wherein the spring element (11) acts in the direction of the second switching position (B2). Control system (1) according to one of the preceding claims, characterized in that the first main stage (6) via the pressure port (2) is pressure-controlled and has a preferably adjustable spring element (12), wherein the pressure in the pressure port (2) in the direction of the first Switching position (A1) acts and the spring element (12) acts in the direction of the second switching position (A2). Pump unit (100) with a control system (1) according to one of the preceding claims and a hydraulic variable displacement pump (109) with at least one actuating cylinder (101), wherein the variable displacement pump (109) is connected to the pressure port (2) of the control system (1) and the Stellyzlinder (101) via the actuating cylinder connection (3) can be acted upon with pressure. Vehicle with a pump set (100) after Claim 9 ,

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