JPH01178783A - Control system for hydraulic actuator - Google Patents

Abstract

PURPOSE:To stabilize the operation of a flow control valve by connecting a first pressure chamber to the upstream side of a resistance part of the passage, and connecting a second pressure chamber to the downstream side of the resistance part of the passage. CONSTITUTION:In a casing 1 a bypass passage 32 branching off from a fluid passage 31 is formed so as to bypass a first pressure chamber 18. The bypass passage 32 and a second pressure chamber 19 are connected through a choke 33 for damping spool vibration, and a pressurized oil in the fluid passage 31 is introduced through the choke 33 and the by-pass passage 32 into the second pressure chamber 19. A spool 17 is moved to a position where a pressure differential between the first and second pressure chambers 18, 19 is balanced with an energizing force of a spring 20, and then stopped.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a control system for a hydraulic actuator such as a hydraulic motor or a hydraulic cylinder, and more specifically to the operation of a flow control valve that controls the flow rate of pressure oil discharged from a hydraulic pump. The present invention relates to a hydraulic actuator control system that stabilizes the hydraulic actuator and controls the operating speed of the hydraulic actuator.

[Conventional technology]

Generally, in a system where the flow rate of pressure oil discharged from a hydraulic pump is controlled by a flow control valve to drive a hydraulic actuator, if the hydraulic actuator has a moment of inertia and an inertial mass, such as a hydraulic motor or hydraulic cylinder, the flow rate is controlled. It is known that the external force acting on the valve spool is accompanied by a time delay, which causes instability of the hydraulic actuator (hunting) accompanied by spool vibration.To solve this problem, a damping throttle is installed in the flow control valve. established,
Research has been reported to reduce the responsiveness of flow control valves and improve the stability of hydraulic systems.

[Problem that the invention seeks to solve]

However, when the hydraulic pump is driven by an automobile engine, the hydraulic pump discharge flow rate increases as the engine speed increases, and if the responsiveness of the flow control ff1l valve is excessively low, the pressure oil to the hydraulic actuator will be reduced. The supply amount suddenly increases and the hydraulic actuator overshoots (turns too much).
This causes problems in terms of noise, durability of the hydraulic actuator, and controllability.

This invention has been made in view of the above points, and its purpose is to provide a hydraulic actuator control system equipped with a flow control valve that can stably and effectively control a hydraulic actuator even when the discharge flow rate of a hydraulic pump suddenly changes. Our goal is to provide the following.

Means for Solving Problem C] In order to achieve the above object, the first to third inventions provide a hydraulic actuator in which the flow rate of pressure oil discharged from a hydraulic pump is controlled by a flow control valve to drive a hydraulic actuator. In the control system, the flow rate control valve is slidably accommodated in a flow path resistance section provided in a discharge side conduit of the hydraulic pump and a valve chamber of a housing, and is configured to control the valve chamber at first and second pressures. A spool that is divided into chambers, and a spring that is provided in the second pressure chamber and is provided to bias the spool toward the first pressure chamber, the first pressure chamber and the flow path resistance. The second pressure chamber and the downstream side of the flow path resistance section are communicated with each other via a choke for damping spool vibration, and the housing is connected to the upstream side of the flow path resistance section. A common configuration is adopted in which a relief passage is provided that opens and closes based on the movement of the spool due to the balance between the differential pressure and the urging force of the spring, and returns excess pressure oil discharged from the hydraulic pump to the suction side of the hydraulic pump.

In the first invention, in the above common configuration, the inner diameter of the choke is d (1 m), the length is 42 (mu), the capacity of the hydraulic pump is qp (cc/rotation), and the spring constant of the spring is k. (kg/mum), the choke inner diameter d1 and choke length β are set so as to satisfy 0.3<qp Hd'/(l·k)<3.

Further, in addition to the above-mentioned common configuration, the second invention includes a configuration in which the second pressure chamber and the downstream side of the flow path resistance portion are connected from the second pressure chamber to the flow path resistance portion in parallel with the choke, which is the common configuration. It is characterized by the provision of a check valve that only allows the flow of pressure oil.

Furthermore, a third aspect of the present invention is characterized in that, in the above-mentioned common configuration, the choke has a larger diameter on the second pressure chamber side and a smaller diameter on the flow path resistance portion side.

[Effect]

Therefore, according to the first invention, the downstream side of the flow path resistance section is connected to the second
The choke leading to the pressure chamber is 0.3 <qP・d'/
(/! −k><3 (qp: pump capacity, k spring constant)
, the choke length β is set, so even if the spool responsiveness decreases excessively or becomes excessively sensitive, or if the discharge flow rate suddenly changes due to changes in the rotation of the hydraulic pump, the hydraulic Excessive overshoot and hunting of the actuator is prevented.

Further, according to the second invention, when the spool moves toward the second pressure chamber, the pressure oil flows out to the flow path resistance section through the choke and check valve, so the response of the spool is improved, and
When the spool moves to the first pressure chamber side, the pressure oil passes only through the choke and flows into the second pressure chamber side, so the response of the spool is slow. Excessive overshoot and hunting on the rotation side are prevented.

Furthermore, according to the third invention, since the choke has a large diameter on the second pressure chamber side and a small diameter on the flow path resistance side, when the spool moves to the second pressure chamber side, the pressure oil flow path resistance side The flow of pressure oil from the flow path resistance section to the second pressure chamber is small, and the spool's responsiveness is improved. The response of the spool is slow, which prevents excessive overshoot and hunting toward high rotation speeds when applied to a hydraulic actuator, such as a hydraulic motor.

[First Embodiment] FIG. 1 shows a first embodiment in which the first invention is embodied in a hydraulic actuator control system for a vehicle.

This will be explained based on FIGS. 2(a) to (fl).

As shown in FIG. 1, a housing 1 is provided with a vane pump 2 as a hydraulic pump that rotates in synchronization with the rotation of an engine (not shown), and a plurality of vanes 5 are slidably provided in a cylinder 3 of the vane pump 2. A rotor 4 is housed therein. The cylinder 3 is provided with two suction ports 6 and two discharge ports 7 alternately at a predetermined interval, each suction port 6 is communicated with a reservoir tank 9 via a suction passage 8 (only one is shown), and each discharge port The port 7 communicates with a discharge passage 10 formed in the housing 1.

A flow control valve 11 is integrally provided in the upper part of the housing 1 to control the flow rate of the pressure oil discharged from the vane pump 2 to adjust the amount of pressure oil supplied to a hydraulic motor 44, which will be described later. That is, the housing 1 has a cylindrical accommodation hole 12 (
A cross-sectional area A1) is installed through it, and a solenoid proportional valve 13 is fixedly installed at one end opening, and a stopper 15 with a packing 50 interposed therein is attached to the other end opening by a circlip 14. Hole 12, electromagnetic proportional valve 13 and stopper 1
5 forms a valve chamber 16.

A spool 17 is accommodated in the valve chamber 16 so as to be slidable in the axial direction, and the spool 17 allows the valve chamber 16 to be moved into the first. It is divided into a second pressure chamber 18,19.

Discharge pressure oil is supplied to the first pressure chamber 18 from the vane pump 2 via the discharge passage 10. Further, in the second pressure chamber 19, the strike collar 1
5 and spool 17, the same spool 17 is always connected to the
A spring 20 is interposed to urge the pressure chamber 18 side.

A base body 21 of the electromagnetic proportional valve 13 is screwed and fixed to the housing 1, and a cylindrical body 22 is screwed to the inner end of the base body 21. Gaskets 51 and 52 are interposed between the outer peripheral surface of the tip end of the base body 21 and the inner peripheral surface of the housing hole 12, and between the end face of the housing 1 and the base body 21, respectively. Base body 21
A valve body 24 that cooperates with the cylinder body 22 to form a variable throttle portion 23 (passage area △2) as a flow path resistance portion is slidably fitted, and the position of the valve body 24 is adjusted. A coil 25 for switching is fitted through an oil seal material 26. A female threaded tube 27 is fitted into the coil 25 from the rear end, and an aperture adjustment screw 28 for adjusting the reference position of the valve body 24 is screwed into this female threaded tube 27. A spring 29 is provided between the throttle adjustment screw 28 and the valve body 24 for always urging the valve body 24 toward the cylinder body 22.
is interposed. A case 30 is fixed to the base body 21 so as to cover the coil 25. Note that the valve body 24 has a variable throttle portion 23 at the rear end of the valve body 24.
A horizontal strip-shaped pressure reduction passage 24a is formed to guide the downstream pressure.

Then, by moving the valve body 24 left and right against the urging force of the spring 29 according to the excitation force of the coil 25, the passage area A2 of the variable throttle part 23 is increased or decreased. The first pressure chamber 18 according to the area A2
A differential pressure (
P+ -P2)' is generated.

A bypass passage 32 branching from the fluid passage 31 is formed in the housing 1 so as to bypass the first pressure chamber 18, and this bypass passage 32 is closed by an embedded plug S. The bypass passage 32 and the second pressure chamber 19 communicate with each other via a choke 33 for damping spool vibration, and the pressure oil in the fluid passage 31 is connected to the second pressure chamber 19 via the bypass passage 32 and the choke 33. It is meant to be guided. As a result, the spool 17 receives a force A1 (P
・-P3).

The spring 20 is moved to a position where -x (k spring constant) is balanced with the biasing force due to the displacement X measured from the natural length of the spring 20, and then stopped. The choke 33 has an inner diameter d, (m+*), and a length n so that o, 3<qp-a4/(ρ・k)<3, where the vane pump capacity is qp (cc/rotation). (dragon) is set. In this example, a vane pump 2 with a pump capacity qp of 13 (CC/rotation) is used, but the pump capacity qp is 8 to 15 (CC/rotation).
cc/revolution) pump.

The housing 1 is provided with a relief passage 34 that communicates the valve chamber 16 with the suction boat 6 of the vane pump 2. This relief passage 34 is connected to the spool 17.
is opened and closed based on the movement of the vane pump 2, and surplus discharge pressure oil from the vane pump 2 is returned to the suction boat 6.

Further, a housing hole 35 is formed in the spool 17 from the second pressure chamber 19 side to the first pressure chamber 18 side. Inside this accommodation hole 35 is a spherical check valve 36 and a valve receiving member 3.
7 and a spring 38 are built in, and a valve seat 39 is screwed into this accommodation hole 35 from the second pressure chamber 19 side. In the center of the valve seat 39 is a passage 4 for deriving pressure oil.
0 is formed, and when the pressure oil in the second pressure chamber 19 becomes abnormally high pressure, the check valve 36 resists the biasing force of the spring 38 and separates from the valve seat 39, releasing the pressure oil into the passage 17a.
It is led to the relief passage 34 through a relief hole 41 provided in the.

A supply passage 43 is provided in the discharge balls 1 to 42 of the fluid passage 31.
A hydraulic motor 44 as a hydraulic actuator is connected to the reservoir tank 9 via a return passage 45, and the pressure oil passing through the variable throttle section 23 is connected to the hydraulic motor 44. It is rotated and returned to the reservoir tank 9 through the return passage 45. Then, the radiator fan 4 is rotated by the rotation of the hydraulic motor 44.
6 is rotated to cool the cooling water.

Next, the operation of the hydraulic motor control system configured as described above will be explained.

Now, when the vane pump 2 is rotated based on the rotation of the engine, pressure oil with a discharge flow rate Q1 is supplied to the first pressure chamber 18.

Here, when the control current to the electromagnetic proportional valve 13 is changed, the passage area A2 of the variable throttle section 23 increases or decreases, and at this time, the pressure oil of the flow rate Q2 that passes through the variable throttle section 23 is expressed by the following equation (1). pass.

Q2-CA2 (2(Pt P2) /ρ)11
2...(1) (C: flow coefficient, ρ: density of working fluid) Then, as the passage area A2 of the variable throttle section 23 changes, the differential pressure between the first pressure chamber 18 and the fluid passage 31 changes. (Pl
-P2) changes, the balance of the force acting on the spool 17 is disrupted, and the pressure oil in the second pressure chamber 19 flows out toward the bypass passage 32 via the choke 33, and the spring 20 expands and contracts. Then, the spool 17 moves. Then, when the forces acting on both ends of the spool 17 are balanced, the spool 17 stops.

Based on this movement of the spool 17, the opening amount of the relief passage 34 increases, and the flow rate Q3 of the pressure oil supplied to the first pressure chamber 18 is transferred to the vane pump 2 through the relief passage 34.
The hydraulic motor 44 is rotated by the pressure oil of the passing flow rate Q2, and the radiator fan 46 is driven to cool the cooling water.

By the way, the equation of motion of the spool 17 is as follows.

-At (Pt P3) +F (x) mS: Mass of spool 17, mass of mp spring 20 bf
: equivalent viscous resistance, cf: damping resistance 7 k; spring 2
0 spring constant, Pl: pressure of the first pressure chamber 18 P3: second
Pressure in the pressure chamber 19, F(x): fluid force Here, the stability of the spool 17 is expressed as (bf + cf)/, bf<<
cf, the stability is dominated by cf/.

Also, the damping resistance of the choke is expressed by the following equation.

128yvβ n128yν d: Choke inner diameter, ΔP: Differential pressure across the choke γ: Specific weight, C: Kinematic viscosity coefficient, l: Choke length Therefore, the viscous resistance cf is c f oc d ' / j2, and the stability of the choke is It is expressed as d4/(g−k).

On the other hand, the change in the pump discharge flow rate due to the change in engine speed is represented by the vane pump capacity, qp (cc/rotation), and the stability and overshoot characteristics of the hydraulic motor 44 are expressed by qp.
It can be expressed by the value −d'/(ff·k).

In other words, as qP·d4/(1·k) becomes smaller, the hydraulic motor 44 improves stability, but overshoot becomes more noticeable, and conversely, as qP·d4/(l·k) becomes larger, overshoot occurs. becomes smaller, but stability decreases.

Therefore, choke inner diameter d, choke length! The spring constant of the spring 20 and the specifications of the 1-vane pump capacity Qp were changed, and the presence or absence of hunting in the hydraulic motor rotational speed and the amount of overshoot were measured, and the following results were obtained.

When the passage area A2 of the variable throttle section 23 is changed by changing the control current l of the electromagnetic proportional valve 13 in the range of qp-d'/(l・k) -0,251<0.3, the second Figure (a
), the hydraulic motor 44 did not cause hunting, but when the vane pump rotational speed Np was changed, the amount of overshoot increased as shown in FIG. 2(b).

Also, 0.3<qp Hd'/(#・k)-〇, 79
When the passage area A2 of the variable restrictor 23 is changed by changing the control current I of the electromagnetic proportional valve 13 in the range of 2<3, the hydraulic motor 44 does not cause hunting as shown in FIG. 2(C). First, when the vane pump rotation speed Np was changed, the amount of overshoot became smaller as shown in FIG. 2(d).

Furthermore, when the control current I or the vane pump rotational speed Np is changed in the range of (lp:d'/(!!・k)-3,72>3, as shown in Fig. 2(e) and (fl), The hydraulic motor 44 caused hunting.

As described above, in this embodiment, the choke 33 for damping spool vibration, which communicates the second pressure chamber 19 and the bypass passage 32, is used.
When the vane pump capacity is qp (cc/rotation) and the spring constant of the spring 20 is k (kg/mu), 0.
Since the inner diameter d (1m) and length β (1m) are set to satisfy 3<(lp ・d4/ (A ・k)<3, the stability and overshoot characteristics of the hydraulic motor 44 are improved. ''Secondly, noise and deterioration of durability can be prevented.

[Second Embodiment] Next, a second embodiment embodying the second invention will be explained based on FIG. Omitted.

Between the second pressure chamber 19 and the bypass passage 32, the first
In place of the choke 33 in the embodiment, a choke 47 whose inner diameter d and flow rate β are not specified is provided in parallel with the choke 47, which allows only the flow of pressure oil from the second pressure chamber 19 to the bypass passage 32, and , a check valve 4 that shuts off the flow of pressure oil from the bypass passage 32 to the second pressure chamber 19;
8 is provided.

Overshooting of the hydraulic motor 44 causes problems with noise and durability of the hydraulic motor 44 only when the engine speed increases rapidly and the hydraulic motor 44 overshoots (turns too much) to the high rotation side. If the rotation speed suddenly decreases and the hydraulic motor 44 overshoots to the low rotation side, noise and durability of the hydraulic motor 44 are not a problem.

On the other hand, in the second embodiment, when the engine speed rapidly increases and the discharge flow rate Q1 of the vane pump 2 increases, when the spool 17 moves to the left, the pressure oil in the second pressure chamber 19 flows through the choke 47 and the check valve. 48 and flows out into the bypass passage 32, the spool 17 moves to the left with good response, and the relief passage 34 is opened and excess discharge pressure oil is returned to the suction boat 6 of the vane pump 2, so that the hydraulic pressure The amount of pressurized oil supplied to the motor 44 does not increase rapidly, thereby preventing the hydraulic motor 44 from excessively overshooting to the high rotation side, thereby preventing noise and deterioration of durability.

Also, when the discharge flow rate Q1 increases, the spool 17
When the spool 17 returns to the right after having moved too far to the left due to inertia, the check valve 48 is closed and the flow of pressure oil through the check valve 48 is cut off, and the pressure oil only flows through the choke 47. From the bypass passage 32 to the second pressure chamber 19
The stability of the spool 17 is increased because of the flow inside.
Hunting of the hydraulic motor 44 can be prevented.

[Third example] Next, a third embodiment embodying the third invention is shown in FIG.

In this embodiment, instead of the choke 33 in the first embodiment, between the second pressure chamber 19 and the bypass passage 32,
A tapered choke 49 is formed with a larger diameter on the second pressure chamber 19 side and a smaller diameter on the bypass passage 32 side. Therefore, when the discharge flow rate Q1 of the vane pump 2 increases, the pressure oil in the second pressure chamber 19 flows out more easily than the tapered choke 49 when the spool 17 moves to the left, as in the second embodiment. Therefore, the spool 17 moves to the left with good response, the relief passage 34 is opened, and excess discharged pressure oil is returned to the suction boat 6 of the vane pump 2, so the amount of pressure oil supplied to the hydraulic motor 44 suddenly increases. As a result, the hydraulic motor 44 does not cause excessive overshoot to the high rotation side, and noise and deterioration of durability can be prevented.

Also, when the discharge flow rate Q1 increases, the spool 17
When the spool 17 returns to the right after moving too far to the left due to inertia, the pressure oil in the bypass passage 32 is difficult to flow into the second pressure chamber 19 through the tapered choke 49.
The stability of the spool 17 is increased, and hunting of the hydraulic motor 44 can be prevented.

In each of the embodiments described above, the control system for the hydraulic motor 44 is used, but the control system for the hydraulic cylinder may also be used.

Effects of the Invention As detailed above, according to the present invention, even when the discharge flow rate of the hydraulic pump changes suddenly, the hydraulic actuator can be controlled stably and well, and the increase in noise and decrease in durability of the hydraulic actuator can be avoided. It has an excellent effect in preventing

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the main parts of a first embodiment in which the first invention is embodied in a hydraulic motor control system; FIG.
C1, (e) is a graph showing the number of rotations of the hydraulic motor when the control current of the electromagnetic proportional valve is changed, Figure 2 (b), (
dl, (o is a graph showing the hydraulic motor rotation speed when changing the hydraulic pump rotation speed, FIG. 3 is a sectional view showing the flow control valve of the second embodiment embodying the second invention, FIG. 4 is a sectional view showing a flow control valve of a third embodiment embodying the third invention. In the figure, 1 is a housing, 2 is a vane pump as a hydraulic pump, 11 is a flow control valve, 17 is a spool, and 20 is a Spring, 23 is a variable throttle part as a flow path resistance part, 33
, 47.49 is a choke, 34 is a relief passage, 44 is a hydraulic motor as a hydraulic actuator, 48 is a check valve, d is the choke inner diameter, β is the choke length, (IP is the vane pump capacity, and k is the spring constant. Patent applicant: Nippondenso Co., Ltd. Toyota Motor Corporation Representative: Patent attorney
H″″：j To retreat, p smoke H? Is the drawing by Ichibata H? Shall we have an audience? Delivered to you

Claims (1)

[Scope of Claims] 1. A hydraulic actuator control system in which the flow rate of pressure oil discharged from a hydraulic pump is controlled by a flow control valve to drive a hydraulic actuator, wherein the flow control valve is connected to a discharge side conduit of the hydraulic pump. a flow path resistance section provided in the second pressure chamber; a spool slidably accommodated in the valve chamber of the housing and dividing the valve chamber into a first and second pressure chamber; and a spool provided in the second pressure chamber; , a spring provided to bias the spool toward the first pressure chamber, and the first pressure chamber communicates with the upstream side of the flow path resistance section, and the second pressure chamber communicates with the upstream side of the flow path resistance section. The downstream side of the flow path resistance section is communicated with the spool via a choke for damping vibration, and the housing is provided with a spool that moves due to the balance between the differential pressure caused by the flow path resistance section and the biasing force of the spring. A relief passage is provided which is opened and closed by the hydraulic pump and returns excess discharge pressure oil from the hydraulic pump to the suction side of the hydraulic pump, and the inner diameter of the choke is d (mm).
, the length is l (mm), and the hydraulic pump capacity is q_p
(cc/rotation), the spring constant of the spring is k (kg
1. A hydraulic actuator control system characterized in that a choke inner diameter d and a choke length l are set so as to satisfy 0.3<q_p・d^4/(l・k)<3 when (/mm). 2 Hydraulic pump capacity q_p is 8 (cc/rotation) to 15 (
cc/rotation). The hydraulic actuator control system according to claim 1. 3. In a hydraulic actuator control system in which the flow rate of pressure oil discharged from a hydraulic pump is controlled by a flow control valve to drive a hydraulic actuator, the flow control valve is a flow path provided in a discharge side pipe of the hydraulic pump. a resistance part, a spool that is slidably accommodated in the valve chamber of the housing and that divides the valve chamber into a first and second pressure chamber; a spring provided to bias the pressure chamber side, the first pressure chamber communicates with the upstream side of the flow path resistance section, and the second pressure chamber communicates with the downstream side of the flow path resistance section. The housing is connected to a certain low pressure side via a choke for damping spool vibration and a check valve that allows only the flow of pressure oil from the second pressure chamber to the flow path resistance section. The hydraulic system is characterized in that a relief passage is provided, which is opened and closed based on the movement of the spool due to the balance between the differential pressure between the parts and the biasing force of the spring, and returns excess pressure oil discharged from the hydraulic pump to the suction side of the hydraulic pump. Actuator control system. 4. In a hydraulic actuator control system in which the flow rate of pressure oil discharged from a hydraulic pump is controlled by a flow control valve to drive a hydraulic actuator, the flow control valve is a flow path provided in a discharge side pipe of the hydraulic pump. a resistance part, a spool that is slidably accommodated in the valve chamber of the housing and that divides the valve chamber into a first and second pressure chamber; a spring provided to bias the pressure chamber side, the first pressure chamber communicates with the upstream side of the flow path resistance section, and the second pressure chamber communicates with the downstream side of the flow path resistance section. are communicated with each other via a choke for damping spool vibration, and the housing is opened and closed based on the movement of the spool due to the balance between the differential pressure caused by the flow path resistance section and the biasing force of the spring, and the hydraulic pressure is A relief passage is provided to return surplus discharge pressure oil from the pump to the suction side of the hydraulic pump, and the choke has a large diameter on the second pressure chamber side and a small diameter on the flow path resistance side. Hydraulic actuator control system.