JPS63195710A - Fluid device - Google Patents

Abstract

PURPOSE:To accurately change and control the discharge value to a set level with no influence of the viscosity change by performing the variable control after detecting the change of the fluid momentum proportional to a mass flow rate. CONSTITUTION:The fluid supplied to the main body of a flow rate detecting part 1 is led into a detection matter 5 at a fixed flow-in angle via a flow-in path 17 formed within the main body of the part 1. The fluid changes its direction in the matter 5 and then led into the main body of the part 1 at a fixed flow-out angle via a flow-out path of the matter 5. In this case, the matter 5 receives the force proportional to a mass flow rate owing to the momentum change of the fluid. A spool 38 interlocking the matter 5 moves up to a position where the balance is secured between said force proportional to the mass flow rate and the energizing force of a mass flow rate setting means 61. Thus, the connection is controlled between an incoming side port 32 and an outgoing side part 33. Then, a discharge value control part 72 of a variable capacity pump 71 is connected with switching to a pressure line 85 and a tank 92. Thus the part 72 is controlled and the discharge value of the pump 71 is pump 71 is variably controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a fluid device that detects the mass flow rate of a fluid and controls the discharge amount of a variable displacement pump.

<Prior Art> Conventionally, as a fluid device for variably controlling the discharge amount of a variable displacement pump, the one shown in FIG. 3 is known (Japanese Unexamined Patent Publication No. 116905/1983). This fluid device connects the pressure port P of the directional control valve 103 to the pressure line 102 of the variable displacement pump 101, and
The pressure before and after 04 is transferred to the pilot chamber 1 of the pressure control valve 105.
06 and the spring chamber 107. Due to the pressure difference between the pilot chamber 106 and the spring chamber 107, the variable displacement pump 1
The anti-spring side of the swash plate control cylinder l01a of 01 is connected to the pressure line 102 and the tank 108 to control the discharge amount of the variable displacement pump 101 to a value corresponding to the throttle opening of the directional control valve 103. This ensures that there is no loss of power.

<Problems to be Solved by the Invention> However, in the conventional fluid device, the pressure control valve 105 compensates for a constant pressure difference between the upstream side and the downstream side.
Since the discharge amount of the variable displacement pump 101 is variably controlled by the opening degree of the variable displacement pump 101, the actual flow rate is not measured and controlled, and there is a problem that the control of the discharge amount becomes uncertain. In other words, the above-mentioned fluid device does not directly detect the flow rate and control the flow rate, but indirectly assumes that if the pressure difference before and after the throttle 104 is constant, a flow rate proportional to the opening of the throttle 104 flows. The flow rate is controlled accordingly.

Therefore, there is a problem in that it is not possible to accurately vary the discharge amount of a flow that causes a change in viscosity, a flow that causes cavitation, a flow that contains bubbles, etc. due to a temperature change.

Therefore, an object of the present invention is to detect the change in the momentum of the fluid proportional to the mass flow rate and variably control the discharge amount. An object of the present invention is to provide a fluid device that can accurately and variably control the discharge amount of the fluid to a set value.

Means for Solving the Problems> In order to achieve the above object, the fluid device of the present invention has the following features:
As illustrated in the figure, a variable displacement pump 71 having a discharge amount control section 72 that variably controls the discharge amount in response to fluid pressure;
A main body 2 having a cylindrical chamber inside, a detection body 5 slidably fitted into the chamber, and a connection between an inlet port 32 and an outlet port 33 in conjunction with the detection body 5. a spool 38 to control and a detection body 5 provided in the main body 2;
a flow rate detection section l having an inflow passage 17 that guides fluid to the main body 2; and an outflow passage 13 provided in the detection body 5 that guides the fluid guided by the inflow passage 17 to the main body 2; The spool 3 is biased by force, and in balance with the force due to the change in momentum of the fluid acting on the detection body 5, the spool 3
8, at least one of the inflow and outflow passages 17.13 is formed at a constant angle of inclination with respect to the axis of the detection body 5;
To the pressure line 85 connected to the variable displacement pump 71,
It is characterized in that the inflow passage 17 of the flow rate detection section 1 is connected, and the inlet port 32 is connected via a pilot line 88, while the outlet port 33 is connected to the discharge control section 72.

Here, the principle of this invention will be explained with reference to FIG.
It will look like this:

The force F acting on the inspection surface S is: The inflow angle of the fluid infiltrating into the test surface q with respect to a certain direction is 01, the outflow angle of the fluid flowing out from the test surface S with respect to the above fixed direction is θ7, the inflow velocity of the fluid into the test surface S is vl, and from the test surface S If the outflow velocity of the fluid is V3, and the flow rate of the fluid flowing into and out of the inspection surface S is Q, then
The equation for the above momentum in a certain direction of the inspection surface S can be expressed as follows.

F−p ・Q(V+cosθ, −v tcosθ,)
・(1) Here, if the cross-sectional area of the inlet for guiding the fluid to the inspection surface S is AI, and the cross-sectional area of the outlet for draining the fluid from the inspection surface S is A, then Equation (1) It becomes % expression %. Therefore, the mass flow rate (ρ・Q) is θ,A.

It can be expressed as a force function in a fixed direction with ρ as a constant, and if the opening degree of the valve is controlled based on the force F representing this flow rate, the flow rate can be directly controlled based on the mass flow rate.

The present invention is constructed with attention paid to this point.

Effect> The fluid supplied to the main body of the flow rate detecting section 1 is guided into the detecting body 5 at a constant inflow angle by the inflow passage 17 provided in the main body. Further, the fluid changes its direction within the detection body 5 and is guided into the main body at a constant outflow angle by an outflow passage 13 provided within the detection body 5. At that time, the detection body 5 receives a force proportional to the mass flow rate due to the change in momentum of the fluid. Therefore, the spool 38 interlocked with the detection body 5 moves to a position where the force proportional to the mass flow rate and the urging force of the mass flow rate setting means 61 are balanced, and the spool 38 moves to the position where the force proportional to the mass flow rate and the urging force of the mass flow rate setting means 61 are balanced, and the inlet port 32 and the outlet port 33 is controlled. Then, the discharge amount control section 72 of the variable displacement pump 71 is switched and connected to the pressure line 85 and the tank 92 to control the discharge amount control section 72, and the discharge amount of the variable displacement pump 71 is variably controlled. therefore,
Even if the flow causes cavitation or contains bubbles, the discharge amount of the variable displacement pump 71 can be accurately controlled to the set flow rate by detecting the mass flow rate.

<Example> Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 shows a fluid system schematically comprising a flow rate detection section 1, a variable displacement pump 71, and a proportional solenoid 61 serving as a mass flow rate setting means.

The flow rate detection unit l includes a main body 2 having a cylindrical shaft hole 2a in the axial direction, a sleeve 3 fitted in the shaft hole 2a,
It includes a cylindrical detection body 5 slidably fitted into the hole 3a of the sleeve 3 and a spool 38 fixed to the detection body 5.

The detection body 5 has a hole 5a extending along the axis from the left end surface 5b in the figure.
, and screw the plug 14 into this hole 5a to close the hole 5a.
A chamber 15 is formed within the detection body 5 by sealing the chamber 15. Further, an annular WIIlla is provided on the outer peripheral surface 5e of the detection body 5, and four holes t1, 11. ... are provided at equal intervals on the circumference. Further, eight outflow passages 13, 13, . .

Four inflow passages 17, 17. which penetrate from the outer peripheral surface 3b of the sleeve 3 to the hole 3a thereof. ... are provided at equal intervals on the circumference. The inflow passages 17, 17. Detection object 5 of...
The inflow angle with respect to the axis of the outflow passage 13°13,...
・Make the same angle θ. In addition, the inflow passages 17, 17
．． The cross-sectional area of... is the outflow passage 13°13,...
be the same as the cross-sectional area of Further, an annular groove 18a is provided on the inner circumferential surface 3a of the sleeve 3, and an annular groove 18a is provided from the outer circumferential surface 3b.
Eight holes 18, 18, . . . communicating with 8a are provided at equal intervals on the circumference.

The main body 2 is provided with an inlet 19 communicating with the annular groove 11a, and the main body 2 is provided with an outlet 21. Further, the four inflow passages 17 and 17 are provided on the inner peripheral surface 2a of the main body 2.
．． An annular groove 20 is provided to communicate the inflow port 19 with the inflow port 19, and the fluid flowing in from the inflow port 19 flows through the inflow passage 17.17.
．． I try to make it flow into... Similarly, the hole 18° I8. ..., the above outlet 21
An annular groove 24 is provided to communicate with the outflow passages 13, 13.
．． The fluid flowing out from... is discharged to the outside from the outlet 21.

On the right side of the flow rate detection section 1 in FIG. 1, there is an inlet port 32.
A housing 37 having a cylindrical valve chamber 36 communicating with the outlet port 33 and the discharge port 35 is arranged. The housing 37 is fixed to the main body 2 with a bolt or the like (not shown) by fitting a protrusion 37b provided on an end surface 37a on the left side in the figure into the inner hole 3a of the sleeve 3. The above valve chamber 36
The spool 38 is slidably fitted into the spool 3.
A land 39 provided at 8 opens and closes between the outlet port 33 and the inlet port 32 and between the outlet port 33 and the discharge port 35. Land 3 above
9 is set to zero wrap with respect to the annular groove 34 communicating with the outlet port 33. Further, a land 40b is formed at one end of the spool 38, and a land 40a is formed at the other end of the spool 38. Then, the land 40a of the spool 38 is fixed to the right end surface 5C of the detection body 5 in the figure via the coupling part 43, and the detection body 5 and the spool 3
8 move as one.

The proportional solenoid 61 has an electromagnetic coil 62 and a movable iron core 6.
3, and the movable iron core 63 has an end surface of its shaft 64 in contact with an end surface of the land 40b of the spool 38.

Therefore, when the electromagnetic coil 62 is excited, the movable iron core 63 urges the spool 38 to the left in the figure with a force proportional to the current applied to the electromagnetic coil.

On the other hand, a cover 51 is fixed to the end surface of the main body 2 with bolts (not shown). . One end surface 5 of the cover 51
A stepped hole 56 is provided in the center of 1a, and a protrusion 58 that protrudes into the left chamber 42 facing the plug 14 is provided in the stepped hole 56.
Fit the cover plug 58 with a and tighten the lock nut 5.
It is fixed at 9. The above cover plug 58 and plug 14
A first spring 54 is compressed between the two, and a second spring 55 is compressed between the right end surface 5c of the detection body 5 and the end surface of the protrusion 37b of the housing 37.

Therefore, when the flow rate detection section l is not operating, the detection body 5
is located at a neutral position due to the urging force of the first spring 54 and the second spring 55, and even if the detection body 5 moves within a predetermined range, the opening of the inflow passage 17, 17, . . . It communicates with the annular groove 11a of the body 5. Note that the space between the stepped hole 56 and the cover plug 8 is sealed with an O-ring 57.

A hole 44 is provided in the sleeve 3 through which the right ventricle 41 facing the right end surface 5c of the detection body 5 is constantly communicated with the outside of the sleeve.
45, and an annular groove 44a communicating with the hole 44.45.
is provided on the outer peripheral surface 3b of the sleeve 3. Similarly, the sleeve 3 is provided with a hole 46, 47 which is always in communication with the left chamber 42 facing the end surface of the plug 14, and an annular groove 46a is provided in the outer peripheral surface 3b of the sleeve 3, which communicates with this hole 46, 47. Further, a communication hole 4 in the main body 2 that communicates with the annular groove 44a is provided.
9 and a communication hole 50 communicating with the annular groove 46a are provided, and the right chamber 41 and the left chamber 42 are opened to the outside of the main body 2.

The variable displacement pump 71 includes a discharge amount control section 72 that variably controls the discharge amount in response to fluid pressure and is formed of, for example, a swash plate control cylinder. The discharge amount control section 72 attempts to maintain the discharge amount of the variable displacement pump 71 at the maximum value by the spring force of the spring 73 when no fluid pressure is applied.

A pressure line 85 connects the discharge side of the variable displacement pump 7I to the inlet 19 of the flow rate detector 1, and a main line 87 is connected to the outlet 21. Further, the inlet port 32 is connected to the pressure line 85 via a pilot line 88.

Further, the outlet port 33 is connected to the side opposite to the spring of the discharge amount control section 72 via a pilot line 91 having a throttle 89, and the discharge port 35 is connected to the tank 92.

Further, the communication hole 49 provided in the main body 2 is connected to the main line 87 via a line 94 having a throttle 93, and the communication hole 50 is connected to the passage 87 via a line 95. Therefore, the chambers 41 and 42 of the flow rate detection section l
Drain generated inside the holes 44, 45, 46, 47 and annular grooves 44a, 46a.

Passage 87 via communication holes 49, 50 and lines 94, 95
is discharged. Movable iron chamber 6 of the proportional solenoid 61
6 is connected to the line 9-4 via line 96,
The proportional solenoid 61 is of oil-immersed type.

The fluid device having the above configuration operates as follows.

The fluid supplied from the variable displacement pump 71 flows into the flow rate detection section I via the pressure line 85.

The fluid that has flowed into the flow rate detection section 1 is transferred to the annular groove 2 of the main body 2.
0. Four inflow passages of sleeve 3 17.17°...,
The annular groove 11a and the four holes 11°11 of the detection body 5,
... and flows into the chamber 15 of the detection object 5. Furthermore, the fluid that has flowed into the chamber 15 flows through the eight outflow passages 13, 13 . ..., sleeve 3rd ring 1J1
8a, eight holes 18, 18. -..., annular groove 2 of main body 2
4 and flows out from the outlet 21.

At this time, the closed curved surface consisting of the outer circumferential surface 5e of the detection body 5 and both end surfaces 5b and 5c of the detection body 5 can be considered as an inspection surface. Therefore, the inflow passages 17, 1
7. . . at a constant angle with respect to the axis of the detection body 5, and the outflow passages 13, +3. The change in momentum within the inspection plane of the fluid flowing out at a constant angle from ... is equal to the force F acting on the object within the inspection plane (in this case, the detection object 5), and this force F is expressed by the above equation. Obtained from (2). As already mentioned, in this embodiment, the inflow passage 1
Angle θ1 of 7,17°... and outflow passages 13,13.・
The angle θ is equal to (=θ), and the cross-sectional area A of the inlet is
, and the cross-sectional area A of the outlet are set equal. Therefore, as expressed by equation (3), the fluid flowing into the inspection surface including the outer circumferential surface 5e and further flowing out from the inspection surface has a force F proportional to the mass flow rate of the fluid on the detection body 5.
acts in the axial direction. Here, the outer circumferential surface of the detection body 5 that forms a part of the inspection surface is the surface 5 e, 5 e, .
... (corresponding to the inner circumferential surface 3a of the sleeve 3).

On the other hand, the biasing force of the proportional solenoid 61 acts on the detection body 5 in a direction opposing the force F.

Therefore, when the flow rate flowing through the detection body 5 becomes larger than the set value, the force F acting on the detection body 5 increases due to a change in the momentum of the fluid, and the detection body 5 moves from the equilibrium position with the proportional solenoid 61 to the proportional solenoid 61. 61 biasing force and 1st. It is displaced to the right in the figure against the biasing force of the second springs 54 and 55. Then, the land 39 of the spool 38 opens the space between the inlet port 32 and the outlet port 33, allowing the fluid supplied via the pilot line 88 to
It is supplied to the side opposite to the spring of the discharge amount control section 72 via a pilot line 91 having a throttle 89.

Then, the swash plate of the variable displacement pump 71 moves in the direction of decreasing the discharge amount, and the discharge amount of the variable displacement pump 71 decreases. Therefore, the discharge amount of the variable displacement pump 71 is controlled to a set value corresponding to the current applied to the proportional solenoid 61. Furthermore, due to this decrease in flow rate, the force F acting on the detection body 5 due to the change in momentum decreases, and the detection body 5 returns to the equilibrium position where it balances the biasing force of the proportional solenoid 61 again.

On the other hand, when the flow rate flowing through the detection body 5 becomes less than the set value, the force with which the fluid acts on the detection body 5 decreases. Then, the detection body 5 moves from the equilibrium position to the proportional solenoid 61.
It is displaced to the left in the figure due to the biasing force of . Then, the land 39 opens the space between the outlet port 33 and the discharge port 35, and discharges the fluid on the side opposite to the spring of the discharge amount control section 72 to the tank 92 via the pilot line 91.

Then, the swash plate of the variable displacement pump 71 moves to the side that increases the discharge amount, and the discharge amount of the variable displacement pump 71 increases. Therefore, the discharge amount of the variable displacement pump 71 becomes the set value. Further, due to the increase in the change in momentum caused by this, the force F acting on the detection body 5 increases, and the detection body 5 returns to the equilibrium position where it balances the biasing force of the proportional solenoid 61 again. That is, by repeating the above-described operation, this fluid device controls the mass flow rate of the pressure line 85 to a mass flow rate corresponding to the preset biasing force of the proportional solenoid 6I.

This fluid device detects the mass flow rate with the detection body 5 and controls the discharge amount of the variable displacement pump 71, so the discharge amount can be variably controlled without being affected by changes in fluid temperature or viscosity. , the discharge amount of a flow in which cavitation' occurs, a flow containing bubbles, etc. can be accurately and variably controlled to a set mass flow rate.

In the above embodiment, since the spool 38 is set to zero wrap and the detection body 5 and the spool 38 are directly connected, the discharge amount control unit 72 can be operated with a slight movement of the detection body 5, resulting in extremely high responsiveness. .

In the above embodiment, the annular groove 11a, the hole 11,
Room 15. Although a flow path consisting of an outflow passage 13 is provided, the present invention allows fluid to flow in at a constant angle to the inspection surface including the outer circumferential surface 5e of the detection body 5, and further to flow out from the inspection surface at a constant angle. It is sufficient that the mass flow rate can be detected by a change in the interlocking amount of , and it is not necessarily necessary to form a flow path in the detection body 5 . In other words, the detection body may have any shape as long as it can convert a change in fluid momentum into force.

Further, in the above embodiment, the sleeve 3 is interposed between the detection body 5 and the main body 2, and the inflow passages 17, 1 are inserted into the sleeve.
7. . . , an annular shape 118a, a hole 18, etc. for flowing out the fluid, but the present invention is not limited to this, and the main body 2 may be provided with an inflow passage and an outflow passage without using the sleeve 3. There is no problem even if it is installed directly. Further, in the above embodiment, the inflow angle θ1 to the detection body 5 and the outflow angle θ from the inside of the detection body 5 are set to the same value, and the cross-sectional area of the inflow port is A.
.

and the cross-sectional area A2 of the outflow port are set to the same value, but in this invention, only one of the inflow angle and the outflow angle may be set to a constant inclination angle, or the inflow angle and the outflow angle may be set to different values. Good too. Further, the cross-sectional areas of the inlet and outlet may be set to different values.

In the above embodiment, the land 38a of the spool 38 is set to zero wrap, but the land 38a is not limited to this, and may be overlapping or ungrabbing. Further, the mass flow rate setting means is not limited to a proportional solenoid, but may be a hand lever that biases a spring.

<Effects of the Invention> As is clear from the above, the fluid device of the present invention includes a variable displacement pump having a discharge m control section that variably controls the discharge amount in response to fluid pressure, a flow rate detection section, and a mass flow rate setting means. A force due to a change in the momentum of the fluid is applied to the detection body of the flow rate detection section, and a spool connected to the detection body is actuated by balancing this force and the force of the mass flow rate setting means, thereby controlling the variable displacement pump. Since the discharge rate is variably controlled by operating the discharge rate control section of the variable displacement pump, the discharge rate of the variable displacement pump can be variably controlled by detecting the mass flow rate of the fluid.
It is possible to accurately control the discharge amount without being affected by changes in viscosity due to changes in the temperature of the fluid, and it is also possible to accurately and variably control the discharge amount of flows that cause cavitation or flows that contain bubbles to the set flow rate. . Further, since the mass flow rate is detected by the flow rate detection section and the discharge amount of the variable displacement pump is variably controlled, only the necessary mass flow rate can be discharged, and therefore energy loss is small.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a fluid device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of the principle of mass flow rate detection, and FIG. 3 is a diagram showing a conventional fluid device. l...Flow rate detection section, 2...Main body, 5...Detection object,
13...Outflow passage, 17...Inflow passage, 32...
Inlet port, 33... Outlet port, 35... Discharge port, 38... Spool, 61... Mass flow rate setting means, 7... Variable displacement pump, 72... Discharge amount control unit . Patent applicant Agent: Daikin Industries, Ltd.
Patent attorney Aoyama Aoyama and 2 others Figure 2 F = 9 ・Q (V, cose, -V2cos
e2) Figure 3

Claims (1)

[Claims] (1) A variable displacement pump (71) having a discharge amount control section (72) that variably controls the discharge amount in response to fluid pressure; a main body (2) having a cylindrical chamber inside; A detecting body (5) that can be fitted freely, and the above detecting body (
5), the inlet port (32) and outlet port (33)
); an inflow passageway (17) provided in the main body (2) that guides the fluid to the detection body (5); a flow rate detection section (1) having an outflow passage (13) that guides the fluid guided by the passage (17) to the main body (2); and urging the detection body (5) with a predetermined force to Detection object (
mass flow rate setting means (61) for operating the spool (38) in balance with the force due to a change in momentum of the fluid acting on the inflow and outflow passages (17), (1);
3), at least one of the passages is formed at a constant angle of inclination with respect to the axis of the detection body (5), while the pressure line (8) connected to the variable displacement pump (71)
5), the inflow passage (17) of the flow rate detection section (1) is connected to the inlet port (32) via the pilot line (88), and the outlet port (32) is connected to the outlet port (5).
33) is connected to a discharge control section (72).