JP3358923B2 - Flow control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow control device for use in a power steering device of an automobile, for controlling a flow rate of a pressure working fluid supplied from a power source to an actuator of the power steering device to a predetermined flow rate. .

[0002]

2. Description of the Related Art In a power steering apparatus which assists manual steering torque using a fluid as a working medium, a pump driven by an internal combustion engine mounted on a vehicle is used as a power source for supplying a working fluid to the power steering apparatus. Is often applied. However, in general, it is desired that the power steering device be able to acquire sufficient steering assisting force when the vehicle is running at a low speed or at a stop, in other words, when the internal combustion engine is driven at a low speed. At the time of rotation drive, from the viewpoint of steering stability,
Does not require much steering assistance. Therefore, a power source whose pump output increases in proportion to the rotation speed of the internal combustion engine cannot be applied as it is.

[0003] Therefore, usually, the power steering apparatus uses a flow rate of a working fluid (hydraulic oil) supplied to the power steering apparatus so that a sufficient power steering operation can be performed in an idling or low rotation range of the internal combustion engine. When the rotational speed of the internal combustion engine is increased to some extent, a flow rate control device that controls the flow rate limited by the orifice and returns the surplus oil to the oil storage tank is applied.

In recent years, the surplus oil flow rate has been increased at a neutral position of steering operation that does not require steering assisting force,
There has been proposed a flow control device that reduces the amount of oil supplied to a power steering device, thereby reducing the amount of work performed by a pump and achieving energy saving.

As this type of flow control device, for example, Japanese Patent Laid-Open Publication No. 6-8840 discloses a spool valve slidably housed in a spool valve housing hole, and a first pressure chamber and a first pressure chamber are formed in the spool valve housing hole. Two pressure chambers are defined, and in the first pressure chamber,
An introduction passage communicating with the discharge passage through the control orifice and a drain passage communicating with the low pressure side are opened, and the pressure of the discharge passage is introduced into the second pressure chamber and the spool valve is biased toward the first pressure chamber. A control spring is accommodated to guide the required flow rate of hydraulic oil from the introduction path to the discharge path via the control orifice, and excess oil corresponding to the required flow rate is returned to the drain path controlled to be opened and closed by the movement of the spool valve. A bypass valve responsive to the pressure of the discharge passage, wherein when the pressure on the discharge passage side drops at a neutral position of the steering operation (the power steering device is not operated) by the bypass valve, The second pressure chamber communicates with the low pressure side to increase the opening area of the drain passage by the spool valve and supply the power to the power steering device. Flow control apparatus that reduce the amount are disclosed.

[0006]

In such a conventional example, the second pressure chamber communicates with the low pressure side by the bypass valve, thereby moving the spool valve which controls the flow rate, and thereby the oil amount in the discharge passage. Is to be reduced.

The pressure in the discharge passage is guided into the second pressure chamber as described above. That is, since the pressure after passing through the control orifice is guided, when the second pressure chamber communicates with the low pressure side, the hydraulic oil after passing through the control orifice drains to the low pressure side. Therefore, even when the power steering device (actuator) is in a non-operating state, a part of the hydraulic oil passes through the control orifice having the flow resistance. For this reason, the pump needs to maintain a predetermined discharge pressure in order for the hydraulic oil to pass through the control orifice, so that the pump performs wasteful work and energy saving cannot be sufficiently achieved. There is a fear.

The present invention has been devised in view of such a conventional situation, and suppresses wasteful energy consumption of a pump when an actuator is in a non-operating state and a required operating oil pressure is low. It is an object of the present invention to obtain a flow control device capable of sufficiently achieving energy saving.

[0009]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a power
A flow control device used in a steering device , wherein a spool valve is slidably received in a spool valve receiving hole, and the spool valve receiving chamber is defined by a first pressure chamber and a second pressure chamber. An introduction passage and a drain passage communicating with the discharge passage through the control orifice are opened in the pressure chamber, and the pressure in the discharge passage is guided into the second pressure chamber and the spool valve is biased toward the first pressure chamber. The control orifice and the discharge passage are separated from the introduction passage by housing the flow control spring.
While guiding the required flow of hydraulic fluid to the power steering device via, the flow control device for recirculating the excess oil to drain passage which is opened and closed controlled by the movement of said spool valve to said required flow rate, the control orifice, said
Configuration in which the opening area is controlled according to the flow rate of the introduction passage
On the other hand, the spool housing hole is provided with respect to the second pressure chamber.
At a position on the opposite side of the first pressure chamber at the axial position of
And a control pressure chamber into which the pressure of the second pressure chamber is led,
One end face between the control pressure chamber and the second pressure chamber is the second pressure chamber.
A movable spring receiving member that faces the pressure chamber and abuts on the flow control spring, and the other end face faces the control pressure chamber with an area larger than the area of the one end face; And a spring member is attached to the power steering device in a non-operating state.
Therefore, when the required operating oil pressure is low, the spring member
Therefore, the movable spring receiving member is moved to the control pressure chamber side.
Reducing the spring force of the flow control spring
The opening surface of the drain passage by the spool valve
The product is increased .

In such a configuration, the hydraulic oil discharged from the pump is guided into the first pressure chamber via the introduction passage. The hydraulic oil introduced into the first pressure chamber is generated only when the restricted flow through the control orifice and when the drain passage is released by the movement of the spool valve based on the differential pressure across the control orifice. The excess oil is diverted from the pressure chamber through the drain passage to the pump suction chamber and the excess oil escaping to the oil storage tank. As a result, the required amount of hydraulic oil is guided to the actuator from the discharge passage under the restriction of the control orifice. For example, in a power steering device, a necessary steering assist force is obtained.

Here, in the present invention, the control spring is in contact with the movable spring receiving member. Since the movable spring receiving member has a larger area on the control pressure chamber side than the area on the second pressure chamber side and has a spring member for urging the control pressure chamber side, the pressure (discharge) on the control pressure chamber side is increased. When the pressure in the passage is equal to the pressure in the second pressure chamber to which the pressure is guided, the spring is biased by the spring member and located far from the second pressure chamber, and when the pressure is high, it is attached to the movable spring receiving member. Move to the second pressure chamber side against the spring force of the spring member,
The control spring is supported at a predetermined position.

That is, when the pressure on the discharge passage side is low, the pressure in the control pressure chamber is also low, the movable spring receiving member is located farthest from the second pressure chamber, and the mounting length of the control spring is long. The spring force (set load) becomes weaker. Therefore, the spool valve is controlled by the control spring having a small set load,
The flow rate passing through the control orifice composed of the main orifice and the sub-orifice is the flow rate shown by AB in FIG.

When the pressure in the control pressure chamber increases, the movable spring receiving member moves toward the second pressure chamber against the spring force of the spring member by the pressure in the control pressure chamber, and gradually compresses the control spring. Increase the set load gradually. Therefore, the movement of the spool valve is controlled based on the slightly increased spring force of the control spring and the pressure difference between the front and rear of the control orifice.
The flow rate is controlled to (b-c when the pump rotation speed is high).

When the pressure in the control pressure chamber reaches a predetermined pressure, the movable spring receiving member comes closest to the second pressure chamber and maximizes the set load of the control spring. In this state, the spool valve controls the flow rate in response to the differential pressure between the control spring and the control orifice, and the flow rate passing through the control orifice is CD in FIG. 3 (c-D in FIG. 3 when the pump rotation speed is high). It is controlled to the maximum flow rate shown in d). Since this maximum flow rate varies depending on the position of the movable spring receiving member, it can be controlled by controlling the movement stop position of the movable spring receiving member.

Next, when the pump rotates at a high speed, the output increases, and the amount of hydraulic oil guided to the introduction passage increases, the opening area of the sub-orifice constituting the control orifice gradually decreases in accordance with the flow rate. Let it. As a result, the flow rate passing through the control orifice composed of the sub orifice and the main orifice gradually decreases.
Flow-down control is performed at a flow rate indicated by (d-c when the pump internal pressure is low).

When the pump output further increases, the sub-orifice arranged in parallel with the main orifice is closed. Therefore, the control orifice becomes only the main orifice, and the substantial opening area of the control orifice is reduced. The flow rate passing through this control orifice is EF in FIG. 4 (e-F when the internal pressure of the pump is low). -F)
Is limited to the flow rate indicated by.

Thus, when the vehicle is running at a low engine speed or running at a low speed or when the vehicle is stopped, the largest flow rate is supplied to the actuator of the power steering device to obtain a sufficient steering assisting force while the wheels are grounded. During high-speed running with low resistance, the output of the pump increases, but the flow rate supplied to the actuator can be reduced, and the steering assisting force can be reduced to ensure steering stability.
Further, when the pump output increases, the flow rate passing through the actuator decreases, so that the temperature rise occurring in the hydraulic oil is effectively suppressed, and the life leading to deterioration is extended.

On the other hand, when the actuator is not operated (for example, in the neutral position of the power steering device), the operating pressure of the discharge passage is reduced. Therefore, the spool valve is controlled by the second pressure to maintain the differential pressure across the control orifice constant. It moves to the second pressure chamber side against the spring force of the control spring in the room, and increases the opening area of the drain passage. Thereby, much of the hydraulic oil introduced into the first pressure chamber from the introduction passage flows into the drain passage, and the pump internal pressure (discharge pressure)
And the workload of the pump is reduced.

At the same time, if the pressure in the discharge passage is reduced while the actuator is not operated, the pressure in the control pressure chamber, where the pressure in the discharge passage is led through the second pressure chamber, decreases. become. Accordingly, the movable spring receiving member receiving the pressure in the control pressure chamber moves toward the control pressure chamber by the spring force of the spring member attached to the movable spring receiving member, and contracts between the movable spring receiving member and the spool valve. This increases the installation length (set length) of the installed control spring.

Therefore, the spool valve that moves by the balance between the differential pressure across the control orifice, that is, the pressure in the first pressure chamber and the pressure in the second pressure chamber plus the spring force of the control spring, has a movable spring receiving member. The movement of the control spring toward the control pressure chamber further reduces the spring force of the control spring, so that the control spring moves further toward the second pressure chamber and further increases the opening area of the drain passage.

Accordingly, the hydraulic oil supplied to the first pressure chamber is returned to the pump suction side and the oil storage tank side from the drain passage having the increased opening area when the actuator does not need the hydraulic oil. Thus, the work of the pump that discharges the working oil to the first pressure chamber through the introduction passage is reduced, and energy saving is advantageously achieved.

In this case, the movable spring receiving member moves by the balance between the spring member attached to the movable spring receiving member and the pressure in the control pressure chamber, and changes the spring force of the control spring. Since the pressure in the second pressure chamber is introduced into the control pressure chamber, part of the pump discharge oil does not pass through the control orifice to move the movable spring receiving member. It is not necessary to maintain the pressure at a predetermined pressure, and it is possible to suppress wasteful energy consumption of the pump and achieve energy saving.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
An embodiment applied to the flow control valve of the power steering device will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a flow control device showing an embodiment of the present invention. In the figure, 1 is a pump body 2
The housing 1 is provided with a spool valve receiving hole 5 having one end sealed with a plug 4 to which a seal ring 3 is attached. It is closed off by a connector 7 which is screwed under the seal by 6.

The connector 7 is provided with a discharge passage 8 communicating with a power steering device (not shown), that is, an actuator, and a stepped hole 51 communicating the discharge passage 8 with the inside of the spool valve receiving hole 5. A hollow stepped sub-spool valve 52 is slidably accommodated in 51. This sub-spool valve 52 is
The first pressure chamber 1 is formed by a spring 54 housed in an intermediate pressure chamber 53 formed between the outer periphery of the body portion of the second body and the stepped hole 51.
While being urged toward the first pressure chamber 15, withdrawal toward the first pressure chamber 15 is prevented by a stop pin 55 implanted in the connector 7.

The hollow interior of the sub-spool valve 52 is the first
Has a passage 56 communicating with the pressure chamber 15, the passage 56, as well as through the inclined passage 5 7 which is formed through the flange portion 52a of the sub-spool valve 52 communicates with the intermediate pressure chamber 53, It communicates with a peripheral groove 59 formed on the inner peripheral surface of the stepped hole 51 through a diametric through hole 58. Further, at the end of the sub spool valve 52 on the side of the discharge passage 8,
An axial main orifice 60 communicating with the passage 56 inside the hollow is formed, and a tapered surface 61 converging toward the discharge passage 8 side is formed. A sub-orifice 62 is formed between the sub-orifice 62 and the corner. Therefore, sub-orifice 6
Numeral 2 is formed in parallel with the main orifice 60, and the main orifice 60 and the sub-orifice 62 constitute a control orifice 9 for restricting the discharge flow rate to the discharge passage 8.

The connector 7 has a circumferential groove 11,
An oblique through hole 12 communicating with the discharge passage 8 is formed in the bottom of the circumferential groove 11 and communicates with the discharge passage 8. 63 are formed. A guide member 64 for supporting the end of the sub-spool valve 52 is provided on the inner periphery of the stepped hole 51 facing the notch 63.
Of the throttle passage 6 between the outer peripheral surface of the
5 are formed.

A spool valve 14 is slidably fitted in the spool valve housing hole 5 whose opening end is closed by the connector 7. The first pressure chamber 15 and the second pressure chamber 16 are defined, and are always biased toward the first pressure chamber 15 by the spring force of the control spring 17 housed in the second pressure chamber 16, and are normally in the normal state. A drain passage 19 communicating with an oil storage tank (not shown) is closed by the land portion 18. Also,
In the first pressure chamber 15 defined by the spool valve 14, an introduction passage 20 for guiding pump discharge oil is opened.

Reference numeral 21 denotes a passage formed in the housing 1. The passage 21 is formed in a blind hole shape substantially in parallel with the spool valve housing hole 5, and the open end thereof is closed by a plug 22 and one end is provided. It communicates with the peripheral groove 11 of the connector 7 through the pressure orifice 23 and the oblique hole 24, and the other end communicates with the inside of the second pressure chamber 16 through the passage 25. The passage 25 is the second
It is bored radially across the pressure chamber 16 and its open end is closed with a plug 26.

As is apparent from the figure, the spool valve 14 has a circumferential groove 27 facing the drain passage 19.
And a diametric through hole 2 opening at the bottom of the circumferential groove 27.
8 and an axial blind hole 29 communicating with the through hole 28 and opening toward the second pressure chamber 16 is provided. In the blind hole 29, the ball valve 30 is biased together with its pusher 31 by a check spring 32. Hollow tail plug 3 fixed to the open end of blind hole 29
A relief valve 34 adapted to the valve seat 3 is provided, and the relief valve 34 detects an excess pressure in the discharge passage 8 guided into the second pressure chamber 16 through the pressure-sensitive orifice 23.
Avoid by the relief operation of. 35 is a hollow tail plug 33
Is a filter provided at the end of the second pressure chamber 16 side.

Reference numeral 36 denotes a control pressure chamber formed between the second pressure chamber 16 and the plug 4, and is formed at the axial right side position of the spool valve housing hole 5. 37 is the control pressure chamber 3
6 is a movable spring receiving member disposed between the second pressure chamber 6 and the second pressure chamber 16. The movable spring receiving member 37 includes a cylindrical portion 38 and a flange portion 39 having a diameter larger than that of the cylindrical portion 38. The cylindrical portion 38 is inserted into the second pressure chamber 16, and one end surface 40 of the cylindrical portion 38 is closed. The flange 39 faces the second pressure chamber 16 and abuts on the flow rate control spring 17.
The other end surface 41 of the flange portion 39 having a larger area than the one end surface 40 faces the control pressure chamber 36. 42 is a passage passing through the movable spring receiving member 37,
The pressure in the second pressure chamber 16 is led into the control pressure chamber 36.

Reference numeral 43 denotes a spring member attached to the movable spring receiving member 37. The spring member 43
6 is located in the spring member housing chamber 44 formed between the bottom surface of the second pressure chamber 16 on the side of the second pressure chamber 16 and the flange 39, and the movable spring receiving member 3
7 is urged toward the control pressure chamber 36 side.

The inside of the spring member accommodating chamber 44 is connected to the drain passage 1 through a pressure-sensitive orifice 45 and an oblique hole 46.
It communicates with 9.

According to this configuration, the pump discharge oil guided from the introduction passage 20 into the first pressure chamber 15 is supplied to the throttle passage 6.
4. a control orifice 9 comprising a passage 56 of the sub spool valve 52, a main orifice 60 and a sub orifice 62;
Through the discharge passage 8.

At this time, in a normal state, the spool valve 14 is urged toward the first pressure chamber 15 by a control spring 17 to close the drain passage 19 with its body (land) 18. The entire amount of the pump discharge oil introduced into the first pressure chamber 15 is guided to an actuator (not shown) through the control orifice 9. On the other hand, the rotation speed of the pump increases, the pump discharge oil amount increases, and the first pressure chamber 1
When the amount of pump discharge oil introduced into the pump 5 increases, the hydraulic oil in the first pressure chamber 15 is guided to the discharge passage 8 under the restricted flow by the control orifice 9, while the differential pressure across the control orifice 9. , The spool valve 14 moves rightward as shown in the figure to open the drain passage 19, and the excess oil is returned from the drain passage 19 to an unillustrated oil storage tank.

Here, in the present invention, the control spring 17 is in contact with the movable spring receiving member 37. Since the movable spring receiving member 37 has a larger area on the control pressure chamber 36 side than an area on the second pressure chamber side 16, the pressure on the control pressure chamber 36 side (the second pressure chamber to which the pressure on the discharge passage 8 side is led) is provided. When the pressure is equal to the pressure in the movable spring receiving member 37, the movable spring receiving member 37 moves toward the second pressure chamber 16 against the spring force of the spring member 43 attached to the movable spring receiving member 37. The control spring 17 is supported at a position where it abuts the step portion 47 of the second pressure chamber 16 (see FIG. 2). Accordingly, the spool valve 14 is configured such that the movable spring receiving member 37
6 and the movable spring receiving member 3
The control spring 17 (support length L
2) a force obtained by adding the pressure in the second pressure chamber 16 to the spring force;
It moves in balance with the force due to the pressure in the first pressure chamber 15 and controls the flow rate.

Next, when the pump rotates at a high speed, the output increases, and the amount of hydraulic oil guided to the introduction passage 20 increases, a pressure difference occurs before and after the throttle passage 65. As a result, the pressure of the hydraulic oil before passing through the throttle passage 65 increases
The sub-spool valve 52 acts leftward against the spring force of the spring 54, and is formed between the tapered surface 61 of the sub-spool valve 52 and the corner of the circumferential groove 59. The sub-orifice 62 is squeezed. The sub-orifice 6 2
4 restricts the flow from the passage 56 through the through hole 58 and the sub-orifice 62, and the flow rate through the control orifice 9 is gradually reduced. In FIG. Flow-down control is performed as shown in -e).

When the pump output further increases, the sub-spool valve 52 further moves to the left to close the sub-orifice 62 arranged in parallel with the main orifice 60. As a result, the control orifice 9 becomes only the main orifice 60, and the substantial opening area of the control orifice 9 is reduced. The flow rate passing through the control orifice 9 is EF (ef) in FIG. ).

The sub-spool valve 52 moves rightward by the spring force of the spring 54 housed in the intermediate pressure chamber 53 when the hydraulic oil pressure before and after the throttle passage 65 becomes substantially equal. The right movement (retreat) is performed by the sub-spool valve 52
Is stopped by the end on the first pressure chamber 15 side contacting the stop pin 55.

As described above, this flow control valve can obtain flow characteristics as shown in FIGS. 3 and 4 by a series of flow control operations, and when the vehicle is running at a low speed or stopped, the maximum flow is controlled. In order to obtain sufficient steering assist force by supplying to the actuator of the steering device, reduce the flow rate supplied to the actuator at high speed running with small wheel ground resistance, reduce the steering assist force to ensure steering stability. can do.

On the other hand, in the inoperative state of the actuator, that is, in the neutral position of the power steering device, the discharge passage 8
In order to keep the differential pressure across the control orifice 9 constant, the spool valve 14 moves toward the second pressure chamber 16 against the spring force of the control spring 17 in the second pressure chamber 16. Thus, the opening area of the drain passage 19 is increased. As a result, most of the hydraulic oil introduced into the first pressure chamber 15 from the introduction passage 20 flows into the drain passage 19, so that the pressure in the pump is reduced and the work of the pump is reduced.

At the same time, when the pressure in the discharge passage 8 decreases while the actuator is not operated, the discharge passage 8
The pressure in the control pressure chamber 36, which is guided through the second pressure chamber 16 through the second pressure chamber 16, also decreases. Thereby, the movable spring receiving member 37 receiving the pressure in the control pressure chamber 36 is
The movable spring receiving member 37 moves to the control pressure chamber 36 side by the spring force of the spring member 43 attached thereto, and stops at the position where the rear end convex portion 48 of the movable spring receiving member 37 contacts the plug 4. When the movable spring receiving member 37 moves away from the second pressure chamber 16, the control spring 17 contracted between the movable spring receiving member 37 and the spool valve 14 has an attachment length L1 (see FIG. 1). This is larger than the mounting length L2 when the pressure in the control pressure chamber 36 is high (see FIG. 2).

Therefore, the spool valve 14 that moves by the balance between the pressure difference between the control orifice 9 and the pressure in the first pressure chamber 15 and the pressure in the second pressure chamber 16 plus the spring force of the control spring 17. The spring force of the control spring 17 is reduced by the amount that the movable spring receiving member 37 moves to the control pressure chamber 36 side, and further moves to the second pressure chamber 16 side to further increase the opening area of the drain passage 19. Increase.

Accordingly, the hydraulic oil supplied into the first pressure chamber 15 is supplied to the drain passage 1 having an increased opening area in a non-operating state where the actuator does not require the hydraulic oil.
It is returned from 9 to the pump suction side and the oil storage tank side (not shown). Therefore, the first pressure chamber 15
The pump that discharges hydraulic oil at a low pressure reduces the discharge pressure, reduces the amount of work, and advantageously achieves energy saving.

Since the control pressure chamber 36 is formed at the axial position of the spool valve housing hole 5, the flow control valve does not become particularly long.

Although the embodiment has been described with reference to the drawings, the specific configuration is not limited to this embodiment, and can be changed without departing from the gist of the invention.
For example, although the passage 42 for guiding the pressure in the second pressure chamber 16 to the control pressure chamber 36 is formed in the movable spring receiving member 37, this passage may be formed in the housing 1 instead.

[0047]

As described above in detail, according to the present invention, when the actuator is in the non-operating state and the required hydraulic oil pressure is low, it is possible to suppress unnecessary energy consumption of the pump. . Therefore, a flow control device capable of sufficiently achieving energy saving can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a flow control device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state in which the pressure of a discharge passage is high and a movable spring receiving member is controlled to stop at a position closest to a second pressure chamber side.

FIG. 3 is a diagram showing flow control characteristics.

FIG. 4 is a diagram showing flow rate control characteristics.

[Explanation of symbols]

 Reference Signs List 5 spool valve receiving hole 8 discharge passage 9 control orifice 14 spool valve 15 first pressure chamber 16 second pressure chamber 17 control spring 19 drain passage 20 introduction passage 36 control pressure chamber 37 movable spring receiving member 40 one end surface 41 other end surface 43 spring Member 60 Main orifice 62 Sub orifice

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-131485 (JP, A) JP-A-63-25176 (JP, A) JP-A-8-282513 (JP, A) JP-A-8-281 216903 (JP, A) Japanese Utility Model 3-112174 (JP, U) Japanese Utility Model 61-222978 (JP, U) Japanese Utility Model Utility Model 51-1116531 (JP, U) (58) Field surveyed (Int. ⁷ , DB name) B62D 5/00-5/32 B62D 6/00-6/06

Claims (4)

(57) [Claims] 1. A flow control system for use in a power steering device.
A control device , wherein a spool valve is slidably housed in a spool valve housing hole, and the spool valve housing chamber is defined as a first pressure chamber and a second pressure chamber. An introduction passage and a drain passage communicating with the discharge passage through the control orifice are opened, and a flow control spring for guiding the pressure of the discharge passage and biasing the spool valve toward the first pressure chamber is accommodated in the second pressure chamber. To guide the required flow rate of hydraulic oil from the introduction passage to the power steering device via the control orifice and the discharge passage, and to supply excess oil to the required flow rate to the drain passage controlled to be opened and closed by movement of the spool valve. In the flow control device for refluxing, the control orifice is moved in accordance with the flow rate of the introduction passage.
The opening area of the spool receiving hole is controlled, while the axial position of the spool accommodation hole with respect to the second pressure chamber is adjusted.
A control pressure chamber is provided at a position opposite to the first pressure chamber to guide the pressure of the second pressure chamber. One end face between the control pressure chamber and the second pressure chamber is Second
A movable spring receiving member is provided which faces the pressure control spring and faces the control pressure chamber with an area larger than the area of the one end face. And a spring member is attached to the power steering device so that the power steering device is in a non-operating state.
When the required operating oil pressure is low, the spring member
By moving the movable spring receiving member to the control pressure chamber side,
By reducing the spring force of the flow control spring,
Increased opening area of the drain passage by the spool valve
Flow control device being characterized in that so as to. 2. An opening area of the control orifice is controlled by a sub-spool valve which responds to a pressure difference between front and rear of a throttle passage provided between the introduction passage and the first pressure chamber. Item 4. The flow control device according to item 1. 3. The control orifice is provided in the sub-spool valve and is arranged in parallel with a main orifice having a fixed opening area. The control orifice has an opening area in accordance with a flow rate of the introduction passage. The flow control device according to claim 2, comprising a controlled sub-orifice. 4. The sub-spool valve is provided in the first pressure chamber, is accommodated in a connector having a hollow spool valve accommodation hole so as to be able to advance and retreat, and has a passage communicating the introduction passage and the discharge passage. The flow control device according to claim 2, wherein the throttle passage is provided on the introduction passage side of the connector, and is provided between the introduction passage and an end of the connector.