JP3358122B2 - 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 Application Laid-Open No. 6-8840 discloses a spool valve slidably housed in a spool valve housing hole and a first pressure chamber in the spool valve housing hole. And a second pressure chamber, and an inlet passage communicating with the discharge passage through a control orifice and a drain passage communicating with the low pressure side are opened in the first pressure chamber, and a discharge passage is formed in the second pressure chamber. And a control spring that guides the pressure and biases the spool valve toward the first pressure chamber.
A flow control device that guides a required flow rate of hydraulic oil from the introduction path to a discharge path via a control orifice, and returns excess oil to the required flow rate to a drain path that is opened and closed by movement of the spool valve. A bypass valve responsive to the pressure of the discharge passage is provided, and when the pressure on the discharge passage side decreases at a neutral position of the steering operation (the power steering device is not operated) by the bypass valve, the second pressure chamber is set to the low pressure side. There is disclosed a flow control device in which the area of the drain passage opened by the spool valve is increased in communication with the spool valve to reduce the amount of oil supplied to the power steering device.

[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 spool valve slidably received in a spool valve receiving hole and defines the spool valve receiving chamber as a first pressure chamber and a second pressure chamber. ,
In the first pressure chamber, an introduction passage and a drain passage communicating with the discharge passage through a control orifice are opened. In the second pressure chamber, the pressure of the discharge passage is guided and the spool valve is moved to the first pressure chamber side. A biased flow 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 a drain controlled to open and close by the movement of the spool valve with respect to the required flow rate. in the flow control device for recirculating the passage, the second
Provided a control pressure chamber in which the pressure in the pressure chamber is guided, between the second pressure chamber and said control pressure chamber, one end face abuts on the flow control spring facing said second pressure chamber, the other end face Is provided with a movable spring receiving member facing the control pressure chamber with an area larger than the area of the one end face, and applies a biasing force to the control pressure chamber side to the movable spring receiving member, thereby moving the movable spring receiving member. Movable spring member to obtain stepwise spring force
Spring received by Rukoto is supplied with the member, the flow control scan
The spring force of the pulling changes according to the pressure of the discharge passage.
It is configured as follows.

According to a second aspect of the present invention, in the configuration of the first aspect of the invention, the spring member attached to the movable spring receiving member is a double nested inner and outer spring member. .

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 flows from the first pressure chamber to the pump suction chamber and the oil storage tank through the drain passage 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 for urging the spool valve 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 includes a spring member for urging the control pressure chamber side, the pressure (discharge passage) in the control pressure chamber is increased. (Equal to the pressure in the second pressure chamber in which the pressure of the second pressure chamber is introduced) is low.
It is far from the pressure chamber. On the other hand, when the pressure in the control pressure chamber is high, the movable spring receiving member moves toward the second pressure chamber against the spring force of the spring member attached to the movable spring receiving member, and moves the control spring to a predetermined position. We support in. Therefore, in the spool valve, the spring receiving member is located at a predetermined position corresponding to the pressure of the control pressure chamber, and the force obtained by adding the pressure in the second pressure chamber to the spring force of the control spring supported by the spring receiving member. Moves in balance with the force of the pressure in the first pressure chamber, and controls the flow rate control.

[0013] The spring member attached to the spring receiving member,
A spring member that obtains a stepwise spring force by moving a movable spring receiving member. In addition to being able to obtain a two-stage spring force by using an inner and outer double nested spring member, a plurality of spring members can be obtained. Can be combined to obtain a multi-step spring force. As the spring member in this case, various spring members such as rubber springs can be adopted in addition to coil springs made of various materials. Therefore, the operation in the case of using a spring member that obtains a two-stage spring force will be described as follows.

That is, when the pressure on the discharge passage side is low, the pressure in the control pressure chamber to which the pressure in the discharge passage is led is also low, and the movable spring receiving member is urged by the spring member to move the pressure from the second pressure chamber most. It is far away. For this reason, since the mounting length of the control spring becomes long, the spring force (set load) of this control spring becomes weak. Accordingly, the spool valve is controlled by the control spring having a small set load, and the flow rate passing through the control orifice is the flow rate indicated by AB in FIG.

At this time, the spring member which is attached to the movable spring receiving member, applies a biasing force to the control pressure chamber to the movable spring receiving member, and obtains a stepwise spring force by moving the movable spring receiving member, The movable spring receiving member is urged with a small spring force.

As the pressure in the discharge passage increases, the pressure in the control pressure chamber to which the pressure in the discharge passage is guided increases. When the pressure in the control pressure chamber increases, the movable spring receiving member moves toward the second pressure chamber side against the spring force of the spring member due to the pressure in the control chamber, and gradually compresses and contracts the control spring. Gradually increase the set load. Therefore, the movement of the spool valve is controlled based on the slightly increased spring force of the control spring and the differential pressure across the control orifice, and the flow rate passing through the control orifice is the flow rate indicated by BC in FIG.

At this time, the spring member attached to the movable spring receiving member exerts a first-stage spring force.

Until the pressure in the control pressure chamber reaches a predetermined pressure and the spring member exerts the spring force in the first and subsequent stages, the movable spring receiving member holds the pressure in the control pressure chamber and the first of the spring member. The spring is kept at a position where it is balanced with the spring force of the step, at which position the set load of the control spring is set to a predetermined value. Therefore, the spool valve controls the flow rate based on the predetermined spring force of the control spring and the differential pressure across the control orifice, and the flow rate passing through the control orifice is the flow rate indicated by CD in FIG.

At this time, the spring member attached to the movable spring receiving member exerts the largest spring force in the first stage.

When the pressure in the control pressure chamber further increases and the hydraulic pressure acting on the movable spring receiving member increases to exceed the maximum spring force in the first stage of the spring member, the movable spring receiving member is moved to the spring member. Then, the control spring is further moved toward the second pressure chamber against the spring force of the next step, and the control spring is gradually compressed to gradually increase the set load. Therefore, the spool valve is controlled to move based on the gradually increased spring force of the control spring and the differential pressure across the control orifice, and the flow rate passing through the control orifice is controlled to the flow rate indicated by DE in FIG. .

At this time, the spring member attached to the movable spring receiving member exerts a spring force after the first stage.

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 controlled to the flow rate indicated by EF in FIG. This flow rate is the maximum flow rate supplied to the actuator.

At this time, the spring member attached to the movable spring receiving member exerts the maximum spring force acting stepwise.

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 set to the second position in order to keep the differential pressure across the control orifice constant. It moves toward the second pressure chamber against the spring force of the control spring in the pressure chamber, and increases the opening area of the drain passage. This allows
Most of the hydraulic oil introduced into the first pressure chamber from the introduction passage flows into the drain passage, so that the pump internal pressure (discharge pressure) is reduced and the work of the pump is reduced.

At the same time, when 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 guided through the second pressure chamber, decreases. Will be. Thus, the 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 spring receiving member, and is contracted between the movable spring receiving member and the spool valve. The mounting length (set length) of the control spring is increased.

Therefore, the spool valve which moves by balancing the differential pressure across the control orifice, ie, the pressure in the first pressure chamber and the pressure in the second pressure chamber plus the spring force of the control spring, is a movable spring receiving member. Is moved to the control pressure chamber side, and the spring force of the control spring is reduced, so that the control spring moves further to the second pressure chamber side to further increase 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 require the hydraulic oil. You. Therefore, the pump that discharges the hydraulic oil to the first pressure chamber through the introduction passage has a reduced discharge pressure, reduces the amount of work, and advantageously achieves energy saving.

In this case, the movable spring receiving member moves by the balance between the spring member attached to the 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 discharge pressure at a predetermined pressure, and it is possible to suppress wasteful energy consumption of the pump and achieve energy saving.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
An embodiment applied to a flow control device of a 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 whose one end is sealed by a plug 4 having a seal ring 3 attached thereto. The open end of the spool valve receiving hole 5 has a seal ring 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 control orifice 9 and a passage 10 communicating the discharge passage 8 with the inside of the spool valve receiving hole 5. Pierce,
Further, a circumferential groove 11 and a diametrical through hole 12 which is open at the bottom of the circumferential groove 11 and communicates with the discharge passage 8 are formed. In addition, the passage 10
Is provided with a diametrical through-hole 13 communicating with.

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,
First pressure chamber 15 defined by the spool valve 14
Is provided with an introduction passage 20 for guiding the pump discharge oil.

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

As apparent from the drawing, 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 third valve seat is provided, and when the pressure in the discharge passage 8 led into the second pressure chamber 16 via the pressure-sensitive orifice 23 is exceeded, the relief operation of the relief valve 34 is performed. To avoid. Reference numeral 35 denotes a filter provided at the end of the hollow tail plug 33 on 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 an axial position of the spool valve housing hole 5.

Reference numeral 37 denotes the control pressure chamber 36 and the second pressure chamber 1
6 is a movable spring receiving member disposed between the movable spring receiving member and the movable spring receiving member. The movable spring receiving member 37 includes a bottomed cylindrical base 38 and the base 3.
8 and an annular flange 39 fixed to the outer periphery of the rim 8. The movable spring receiving member 37 is provided on the cylindrical portion 3 of the base 38.
8 a is inserted into the second pressure chamber 16, one end surface 40 of the cylindrical portion 38 a side faces the second pressure chamber 16 and abuts on the flow rate control spring 17, and the flange 39 is connected to the control pressure chamber 36. The other end surface 41 on the side of the flange 39 having an area larger than the one end surface 40 faces the control pressure chamber 36. Reference numeral 42 denotes a pressure-sensitive passage penetrating the base 38 of the movable spring receiving member 37, and guides the pressure in the second pressure chamber 16 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 is an inner / outer double nested spring member comprising a large diameter spring 43a and a small diameter spring 43b. Second pressure chamber 16 side bottom surface 36a
The movable spring receiving member 37 can be urged toward the control pressure chamber 36 in the spring member housing chamber 44 formed between the spring member 39 and the flange 39. The large-diameter spring 43a is contracted with a predetermined set load between the bottom surface 36a of the control pressure chamber 36 on the second pressure chamber 16 side and the flange 39, and the small-diameter spring 43a
b is contracted with a predetermined set load between a movable stopper 45 and a flange 39 attached to the outer periphery of the cylindrical portion 38a of the base 38 so as to be movable by a fixed length in the axial direction.

That is, the movable stopper 45 is provided with a step 38 b formed on the outer periphery of the base 38 of the movable spring receiving member 37.
When the movable spring receiving member 37 is at a position farthest from the second pressure chamber 16 (the rightmost position in the figure), the control is performed as shown in FIG. It stops at a position where it does not come into contact with the end surface 36a of the pressure chamber 36 on the second pressure chamber 16 side. Therefore, when the movable spring receiving member 37 is at the position shown in FIG. 1, the large-diameter spring 43a of the spring member 43 applies a biasing force toward the control pressure chamber 36 to the movable spring receiving member 37, but the small-diameter spring 43b The spring force does not contribute to the movement of the movable spring receiving member 37 at all.

The reason why the spring force of the small diameter spring 43b of the spring member 43 gives an effective biasing force to the movable spring receiving member 37 is that the movable spring receiving member 37 is controlled by the pressure in the control pressure chamber 36, as will be described in detail later. Moves to the second pressure chamber 16 side, and the movable stopper 45 moves to the second pressure chamber 1 of the control pressure chamber 36.
This is after the contact with the sixth side end surface 36a.

The interior of the spring member housing chamber 44 communicates with the drain passage 19 through a pressure-sensitive orifice 46 and a slant hole 47.

According to this configuration, the pump discharge oil guided from the introduction passage 20 into the first pressure chamber 15 is supplied to the through hole 13, the passage 10, and the orifice 9 formed in the connector 7.
Through the discharge passage 8.

At this time, under normal conditions, the spool valve 14 is urged toward the first pressure chamber 15 by a control spring 17, and the body (land) 18 closes the drain passage 19. 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, when the rotation speed of the pump increases and the amount of oil discharged from the pump increases, and the amount of oil discharged from the pump introduced into the first pressure chamber 15 increases, the first pressure chamber 15 While the hydraulic oil in the orifice is guided to the discharge passage 8, the orifice 9
The spool valve 14 moves rightward as shown in FIG. 1 on the basis of the pressure difference between the front and rear sides to open the drain passage 19, and the excess oil is returned from this drain passage 19 to an unillustrated oil storage tank.

Here, in the present invention, the control spring 17 for urging the spool valve 14 is in contact with the movable spring receiving member 37. This movable spring receiving member 37
Since the area on the control pressure chamber 36 side is larger than the area on the second pressure chamber side 16 and the spring member 43 for urging the control pressure chamber 36 side is attached, the pressure in the control pressure chamber 36 (discharge passage 8 (Equal to the pressure in the second pressure chamber 16 into which the pressure on the side is guided) is low,
It is located far from the pressure chamber 16 (see FIG. 1). On the other hand, when the pressure in the control pressure chamber 36 is high, 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. Thus, the control spring 17 is supported at a position where the distal end of the cylindrical portion 38a contacts the shoulder 48 formed in the second pressure chamber 16 (see FIG. 5). Therefore, the spool valve 14 has a spring receiving member 37 at a predetermined position corresponding to the pressure of the control pressure chamber 36, and the control spring 17 supported by the spring receiving member 37 (the mounting length is L1 to L1).
2) and the flow is controlled by balancing the force obtained by adding the pressure in the second pressure chamber 16 to the spring force of the second pressure chamber 16 and the force generated by the pressure in the first pressure chamber 15.

More specifically, when the pressure on the discharge passage 8 side is low, the pressure in the discharge passage 8 is also low in the control pressure chamber 36 guided through the second pressure chamber 16, and the movable spring receiving member 37 is biased by the spring member 43, and the stop projection 38c formed on the base 38 is in the position farthest from the second pressure chamber 16 in contact with the plug 4 (see FIG. 1). For this reason, the mounting length of the control spring 17 is the longest, and the spring force (set load) of the control spring 17 is weak. Therefore, the spool valve 14 is controlled by the control spring 17 having a small set load, and the flow rate passing through the control orifice 9 is represented by AB in FIG.
The flow rate is indicated by. This flow rate is a flow rate when the power steering device to which the hydraulic oil is guided through the discharge passage 8 does not require a steering assisting force or does not perform a steering operation.

At this time, the large-diameter spring 43 of the spring member 43 attached to the movable spring receiving member 37 has one end in contact with the end surface 36a of the control pressure chamber 36 on the side of the second pressure chamber 16 and is biased toward the movable spring receiving member 37. Although a force is applied, the small-diameter spring 43 has one end in contact with the movable stopper 45, and thus does not exert a spring force for biasing the movable spring receiving member 37 in the axial direction (see FIG. 1). Therefore, the spring member 43 urges the movable spring receiving member 37 toward the control pressure chamber 36 with the smallest spring force.

When the power steering device (not shown) starts to be steered, the pressure in the discharge passage 8 rises, and the pressure in the discharge passage 8 is increased by the through hole 12, the circumferential groove 11, the oblique hole 24, and the pressure-sensitive orifice. The pressure is guided into the second pressure chamber 16 via the passage 23, the passage 21 and the passage 25 and further into the control pressure chamber 36 via the pressure-sensitive passage 42, and the pressure in the control pressure chamber 36 increases. When the pressure in the control pressure chamber 36 increases, the pressure in the control chamber 36 causes the movable spring receiving member 37 to move toward the second pressure chamber 16 against the spring force of the spring member 43 (see FIG. 2). Then, the control spring 17 is gradually compressed, and the set load of the control spring 17 is gradually increased. Therefore, the movement of the spool valve 14 is controlled based on the slightly increased spring force of the control spring 17 and the differential pressure across the control orifice 9,
The flow rate passing through the control orifice 9 is the flow rate indicated by B-C in FIG.

At this time, as for the spring member 43 attached to the movable spring receiving member 37, only the large-diameter spring 43a whose one end is in contact with the second pressure chamber 16 side end surface 36a of the control pressure chamber 36 acts as a spring. The first stage spring force is exerted (see FIG. 2).

Until the pressure in the control pressure chamber 36 reaches a predetermined pressure and the spring member 43 exerts the spring force after the first stage, that is, the variable stopper 45 is
Until the small-diameter spring 43b exerts a spring force in contact with the end surface 36a, the movable spring receiving member 37 holds the control pressure chamber 3
6 and the maximum value of the first-stage spring force of the spring member 43 (the spring force of the large-diameter spring 43a) is maintained at a balanced position (see FIG. 3), and the set load of the control spring 17 is reduced at that position. Set to a predetermined value. Therefore, the spool valve 14
Controls the flow rate based on the predetermined spring force of the control spring 17 and the differential pressure across the control orifice 9, and the flow rate passing through the control orifice 9 is the flow rate indicated by CD in FIG.
This flow rate is a flow rate that is supplied from the discharge passage 8 to a power steering device (not shown) when the steering operation is performed during high-speed running of the vehicle.

At this time, the large diameter spring 43a of the spring member 43 attached to the movable spring receiving member 37 is compressed until the variable stopper 45 comes into contact with the end surface 36a of the control pressure chamber 36, so that the spring in the first stage is A large spring force is exerted (see FIG. 3).

When the pressure in the control pressure chamber 36 further increases and the hydraulic pressure acting on the movable spring receiving member 37 increases and exceeds the maximum spring force of the spring member 43 in the first stage, the movable spring receiving member 37 The member 37 further moves to the second pressure chamber 16 side against the spring force of the next stage of the spring member 43 (see FIG. 4), and gradually compresses the control spring 17 to gradually increase the set load. Therefore, the spool valve 14
Is controlled based on the gradually increased spring force of the control spring 17 and the differential pressure across the control orifice 9, and the flow rate passing through the control orifice 9 is controlled to the flow rate indicated by DE in FIG.

At this time, the spring member 43 attached to the movable spring receiving member 37 includes a movable stopper 45 to which one end of the small-diameter spring 43b contacts with the spring force of the large-diameter spring 43a.
Comes into contact with the end surface 36a of the control pressure chamber 36, and the small-diameter spring 43b is compressed and exerts the second-stage spring force (see FIG. 4).

When the pressure in the control pressure chamber 36 reaches a predetermined pressure, the movable spring receiving member 37 comes closest to the second pressure chamber 16, and the tip of the cylindrical portion 38 a is moved to the second pressure chamber 16.
It stops at the position where it abuts the shoulder 48 formed therein, and the set load of the control spring 17 is maximized (see FIG. 5).
In this state, the spool valve 14 is controlled by the control spring 17.
In response to the differential pressure across the control orifice 9, the flow rate is controlled, and the flow rate passing through the control orifice 9 is controlled to the flow rate indicated by EF in FIG. This flow rate is the maximum flow rate supplied to the actuator.

At this time, the spring member 43 attached to the movable spring receiving member 37 includes a large-diameter spring 54a and a small-diameter spring 4a.
3b is compressed most, and exerts the maximum spring force acting stepwise (see FIG. 5).

On the other hand, in the inoperative state of the actuator, that is, in the neutral position of the power steering device, the operating pressure of the discharge passage 8 decreases. Therefore, in order to keep the differential pressure across the control orifice 9 constant, the spool valve 14 is required. It moves toward the second pressure chamber 16 against the spring force of the control spring 17 in the second pressure chamber 16 and increases the opening area of the drain passage 19. As a result, much 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 is reduced while the actuator of the power steering device is not operated, the pressure in the discharge passage 8 is controlled by the control pressure chamber 36 which is guided through the second pressure chamber 16. Will decrease. Thereby, the spring receiving member 37 receiving the pressure in the control pressure chamber 36 moves toward the control pressure chamber 36 by the spring force of the spring member 43 attached to the spring receiving member 37, and the stop projection of the spring receiving member 37 38c is plug 4
Stop at the position where it abuts. As the spring receiving member 37 moves toward the control pressure chamber 36, the length of the control spring 17 contracted between the movable spring receiving member 37 and the spool valve 14 becomes L1 (see FIG. 1). The installation length L2 when the pressure in the pressure chamber 36 is high (FIG. 5)
Reference)).

Therefore, the spool valve which 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. 14 moves further toward the second pressure chamber 16 by reducing the spring force of the control spring 17 to the extent that the movable spring receiving member 37 moves toward the control pressure chamber 36, further increasing the opening area of the drain passage 19. Increase.

Accordingly, the hydraulic oil supplied into the first pressure chamber 15 is supplied from the drain passage 19 having the increased opening area to the pump suction side (not shown) and the non-operating state where the actuator does not require the hydraulic oil. It is returned to the oil storage tank side. Therefore, the pump that discharges the working oil to the first pressure chamber 15 through the introduction passage 20 has a reduced discharge pressure, reduces the amount of work, and advantageously achieves energy saving.

In this case, the movable spring receiving member 37
Moves due to the balance between the spring member 43 attached to the spring receiving member 37 and the pressure in the control pressure chamber 36, and changes the spring force of the control spring 17. Since the pressure in the second pressure chamber 16 is guided into the control pressure chamber 36, a part of the pump discharge oil passes through the control orifice 9 in order to move the movable spring receiving member 37. Therefore, it is not necessary to maintain the pump discharge pressure at a predetermined pressure, and it is possible to suppress wasteful energy consumption of the pump and achieve energy saving.

Further, 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 spirit of the invention.
For example, the pressure in the second pressure chamber 16 is controlled by the control pressure chamber 36.
Is formed in the spring receiving member 37, but a passage may be formed in the housing 1 instead.

The small diameter spring 43b of the spring member 43
Has been described in which one end is supported by the movable stopper 45. Instead, the movable stopper 45 is eliminated and the free length of the small-diameter spring 43b is reduced by the movable spring receiving member 37.
Is located farthest from the second pressure chamber 16, one end of the small-diameter spring 43b has a length that does not contact the end surface 36a of the control pressure chamber 36, so as to constitute a spring member that obtains a stepwise spring force. You may.

[0062]

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 has slightly moved to a second pressure chamber side.

FIG. 3 is a cross-sectional view showing a state in which the movable spring receiving member further moves toward the second pressure chamber and the movable stopper comes into contact with the end surface of the control oil chamber.

FIG. 4 is a cross-sectional view showing a state in which the movable spring receiving member further moves toward the second pressure chamber, and the large-diameter spring and the small-diameter spring of the spring member are exerting a spring action.

FIG. 5 is a cross-sectional view showing a state in which the movable spring receiving member further moves toward the second pressure chamber, and the distal end of the cylindrical portion of the movable spring receiving member comes into contact with the shoulder of the second pressure chamber and stops. .

FIG. 6 is a diagram showing flow control characteristics.

[Explanation of symbols]

 Reference Signs List 5 spool valve accommodation 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 the other end surface 43 spring Element

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-131485 (JP, A) JP-A-63-25176 (JP, A) JP-A-8-216903 (JP, A) JP-A-8-216903 276855 (JP, A) JP-A-59-38167 (JP, A) JP-A-8-282513 (JP, A) JP-A-51-116531 (JP, U) JP-A-61-42384 (JP, U) (58) Field surveyed (Int.Cl. ⁷ , DB name) B62D 5/00-5/32 B62D 6/00-6/06

Claims (2)

(57) [Claims] A spool valve is slidably housed in a spool valve housing hole, the spool valve housing chamber is defined as a first pressure chamber and a second pressure chamber, and a control chamber is provided in the first pressure chamber. An introduction passage and a drain passage communicating with the discharge passage through the 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 housed in the second pressure chamber. In the flow control device, the required flow rate of hydraulic oil is guided 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 that is opened and closed by the movement of the spool valve. Providing a control pressure chamber into which the pressure of the second pressure chamber is led,
Between the serial control pressure chamber and the second pressure chamber, one end face abuts on the flow control spring facing said second pressure chamber,
A movable spring receiving member facing the control pressure chamber with the other end surface having an area larger than the area of the one end surface is provided, and a biasing force toward the control pressure chamber is applied to the movable spring receiving member.
The Rukoto spring member to obtain a stepwise spring force by the movement of the movable spring bearing member is supplied with the movable spring receiving member,
The spring force of the flow control spring is equal to the pressure of the discharge passage.
A flow control device characterized in that the flow control device is configured to change in accordance with the flow rate. 2. The spring member attached to the movable spring receiving member comprises a double inner / outer nested spring member.
A flow control device as described.