JP3207086B2 - 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 rotation speed of the internal combustion engine becomes high to some extent, a flow rate control device that controls the flow rate limited by the orifice to return the excess 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 a flow control device of this type, 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 and a second 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 spool valve in which a spool valve is slidably received in a spool valve receiving hole, and the first and second pressure chambers are defined in the spool valve receiving hole.
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 biasing 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, while the excess oil corresponding to the required flow rate is controlled to be opened and closed by movement of the spool valve. In the flow control device for recirculating, the spool valve, a bottomed cylindrical outer spool having a through hole at the bottom,
The outer spool has a large-diameter portion inserted into the inner periphery of the cylindrical portion and an inner spool having a small-diameter portion inserted into the through-hole. The bottom portion of the outer spool faces the second pressure chamber. A low-pressure chamber is formed between the inner periphery of the cylindrical portion of the spool and the outer periphery of the small-diameter portion of the inner spool, while the control spring acts on the inner spool, and further, an inner spool is provided between the inner spool and the outer spool. A spring member for urging the outer spool toward the second pressure chamber and urging the outer spool toward the second pressure chamber is attached.

Further, the spring member is housed in the low-pressure chamber.

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 spool valve comprises an inner spool and an outer spool, and between the inner spool and the outer spool, the inner spool is biased to the first pressure chamber, and A spring member for urging the spool toward the second pressure chamber is attached, and the control spring acts on the inner spool. Therefore, when the pressure in the first pressure chamber and the pressure in the second pressure chamber are low, the outer spool is in a position urged toward the second pressure chamber by a spring member attached thereto, and the spool valve is moved forward and backward of the control orifice. The flow rate is controlled by the pressure and the spring force of the control spring. When the pressures in the first pressure chamber and the second pressure chamber are high, the outer spool moves toward the second pressure chamber against the spring force of the spring member by the pressure in the second pressure chamber and reaches a predetermined position. At that position, the spool valve controls the flow rate.

That is, when the pressure in the first pressure chamber is low, that is, when the pressure in the pump is low, the outer spool is at a position urged toward the second pressure chamber by the spring member, and in this state, the outer spool is integrated with the inner spool. This constitutes a spool valve. Therefore, the spool valve moves based on the 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 AB in FIG.

Next, when the pressure in the first pressure chamber increases, the flow rate passing through the control orifice also increases, and the pressure in the discharge passage also increases. Therefore, the pressure in the second pressure chamber to which the pressure in the discharge passage is led increases. When the pressure in the second pressure chamber increases and exceeds the spring force of the spring member, the outer spool moves toward the first pressure chamber to a position where the spring force of the spring member balances the pressure in the second pressure chamber, and Reduce the opening area of the passage. As the opening area of the drain passage becomes smaller, the differential pressure across the control orifice increases accordingly, so the spool valve moves toward the second pressure chamber against the spring force of the control spring to keep this differential pressure constant. It moves and controls the flow rate at a position where the differential pressure across the control orifice and the spring force of the spring member and the control spring are balanced.
As a result, the flow rate passing through the control orifice becomes B in FIG.
The flow rate is indicated by -C.

When the pressure in the first pressure chamber and the pressure in the second pressure chamber reach a predetermined pressure, the outer spool presses the spring member most and comes closest to the first pressure chamber side. 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 CD in FIG. This flow rate is the maximum flow rate supplied to the actuator, and is usually controlled to this flow rate.

On the other hand, when the actuator is not operated (for example, at the neutral position of the power steering device), the operating pressure of the discharge passage is reduced, so that the pressure of the second pressure chamber is also reduced. Therefore, the spool valve moves toward the second pressure chamber against the spring force of the control spring in the second pressure chamber in order to keep the differential pressure across the control orifice constant, increasing the opening area of the drain passage. As a result, much 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 decreases when the actuator is not operated and the pressure in the second pressure chamber decreases, the outer spool receiving the pressure in the second pressure chamber is attached to the outer spool. The spring member moves toward the second pressure chamber due to the spring force of the spring member.

Therefore, the spool valve composed of the inner and outer dual spools generates a 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 force obtained by adding the spring force of the control spring. In the case where the outer spool is moved to the second pressure chamber side, the opening area of the drain passage opened by the spool valve further increases when the outer spool moves to the second pressure chamber side.

Accordingly, the hydraulic oil supplied to the first pressure chamber is returned to the pump suction side and the oil storage tank side via the drain passage having an increased opening area when the actuator does not need the hydraulic oil. By doing so, the pump that discharges the working oil to the first pressure chamber via the introduction passage has a reduced discharge pressure and a reduced amount of work,
Energy saving is advantageously achieved.

In this case, the outer spool moves by the balance between the spring member attached to the outer spool and the pressure in the second pressure chamber, and changes the opening area of the drain passage. Therefore, since a part of the pump discharge oil does not pass through the control orifice to move the outer spool, it is not necessary to maintain the pump discharge pressure at a predetermined pressure, thereby suppressing unnecessary energy consumption of the pump. do it,
Energy saving can be achieved.

[0021]

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, and the open end of the spool valve receiving hole 5 is twisted under sealing by a seal ring 6. It is closed by the connector 7 which is fixed.

The connector 7 is provided with a discharge passage 8 communicating with a power steering device, not shown, 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. In addition, a peripheral groove 11 and a diametrical through hole 12 which is open at the bottom of the peripheral groove 11 and communicates with the discharge passage 8 are formed. A diametric through hole 13 communicating with the passage 10 is provided at the opening end of the passage 10.

A spool valve 50 composed of an inner spool, 51 and an outer spool 52 is slidably fitted in the spool valve receiving hole 5 whose opening end is closed by the connector 7. Reference numeral 50 denotes a first pressure chamber which defines the inside of the spool valve accommodating hole 5 as a first pressure chamber 15 and a second pressure chamber 16 and which always has the spring force of a control spring 17 housed in the second pressure chamber 16. The drain passage 19 is biased toward the side 15 and is normally closed by a land portion 18 (specifically, a land portion of the outer spool 52) which communicates with an oil storage tank (not shown). The first pressure chamber 15 defined by the spool valve 50 has an introduction passage 20 for introducing pump discharge oil.

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 has an open end closed by a plug 22 and one end thereof. It communicates with the peripheral groove 11 of the connector 7 through the pressure-sensitive orifice 23 and the oblique hole 24, and the other end communicates with the second pressure chamber 16 through the passage 25. The passage 25
Is bored radially across the second pressure chamber 16 and has an open end closed by a plug 26.

As described above, the spool valve 50 includes an inner spool 51 and an outer spool 52. The outer spool 52 has a bottomed cylindrical shape as a whole and has a through hole 53 in a bottom portion 52b. A large-diameter portion 51a inserted into the inner periphery of the cylindrical portion 52a of the outer spool 52,
Similarly, the outer spool 52 has a small diameter portion 51b to be inserted into the through hole 53. The cylindrical portion 52a of the outer spool 52 faces the first pressure chamber 15, and the bottom portion 52b faces the second pressure chamber 16. is there.

The outer spool 52 is formed with a circumferential groove 54 communicating with the drain passage 19 and a diametrical through hole 55 opening at the bottom of the circumferential groove 54. Inner circumference and the inner spool 5
A low-pressure chamber 56 communicating with the drain passage 19 through the through hole 55 is formed between the small-diameter portion 51b and the outer periphery of the small-diameter portion 51b.

The low pressure chamber 5 is provided on the inner spool 51.
6 and a diametric through-hole 57 communicating with 6
A stepped through hole 58 in the axial direction communicating with the first pressure chamber 15 is provided, and the open end of the first pressure chamber 15 side is closed with a plug 59.
In the stepped through hole 58, there is provided a relief valve 34 which is biased by the check spring 32 together with the pusher 31 of the ball valve 30 and adapted to the valve seat 33 formed in the step of the stepped hole 58. This relief operation of the relief valve 34 avoids an excess pressure in the discharge passage 8 guided into the second pressure chamber 16 via the pressure-sensitive orifice 23. Reference numeral 35 denotes a filter provided at the end of the stepped through hole 58 on the second pressure chamber 16 side.

A spring receiving member 60 is mounted on the outer periphery of the inner spool 51 and supports the control spring 17. The spring receiving member 60 also functions as a stop member that regulates the maximum movement position of the outer spool 52 toward the second pressure chamber 16.

Reference numeral 61 denotes a spring member disposed between the inner spool 51 and the outer spool 52. The spring member 61 is housed in the low-pressure chamber 56,
1 is urged toward the first pressure chamber, and the outer spool 52 is urged toward the second pressure chamber 16.

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

At this time, in a normal state, the outer spool 52 is biased by the spring member 61 and its bottom 5
The control spring 17 urges the second pressure chamber 2b toward the first pressure chamber 15 in a state where the second pressure chamber 2b is in contact with the spring receiver 60 also serving as a stop member.
9 is closed, and the entire amount of 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 pump discharge oil amount increases, and the pump discharge oil amount introduced into the first pressure chamber 15 increases, the first pressure chamber 15 While the hydraulic oil inside is guided to the discharge passage 8, the spool valve 50 moves rightward as shown in the drawing based on the differential pressure across the control orifice 9 and pushes the control spring 17 until it reaches a predetermined length. The drain passage 19 is opened, and the drain passage 19 is opened.
The excess oil is returned to the oil storage tank (not shown).

Here, in the present invention, the spool valve 5
Reference numeral 0 denotes an inner spool 51 and an outer spool 52. Between the inner spool 51 and the outer spool 52, the inner spool 51 is biased toward the first pressure chamber 15, and the outer spool 52 is A spring member 61 biasing toward the 16 side is attached, and the control spring 17 acts on the inner spool 51. Thereby, the first pressure chamber 15
When the internal pressure and the pressure in the second pressure chamber 16 are low, the outer spool 52 is urged toward the second pressure chamber 16 by the spring member 61, and the bottom portion 52b is at the position where the stop member 60 is stopped. 50 presses and shrinks the control spring 17 to a predetermined length (L1).
It moves based on the spring force and the differential pressure across the control orifice 9 to control the flow rate (see FIG. 1). On the other hand, the first pressure chamber 1
When the pressure in the second pressure chamber 16 and the pressure in the second pressure chamber 16 are high, the outer spool 52 moves toward the first pressure chamber 15 against the spring force of the spring member 61 due to the pressure in the second pressure chamber 16, and The end of the portion 52a reaches a position where it comes into contact with the flange portion 59a of the plug 59 (see FIG. 2). Therefore, since the outer spool 52 moves and the relative position between the spool valve 50 and the drain passage 19 changes, the spool valve 50 further compresses the control spring 17 (dimension L2), and It moves by the balance between the force obtained by adding the force of the spring member 61 to the force generated by the pressure in the second pressure chamber 16 and the force obtained by adding the spring force of the spring member 61 to the force generated by the pressure in the first pressure chamber 15. Will be in charge.

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 50 moves toward the second pressure chamber 16 against the spring force of the control spring 17 in the second pressure chamber 16 since the operating pressure of the control orifice 9 decreases. Thus, the opening area of the drain passage 19 is increased. 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 decreases while the actuator is not operated, the second pressure chamber 16
The internal pressure will also drop. As a result, the outer spool 52 receiving the pressure in the second pressure chamber 16 moves toward the second pressure chamber 16 by the spring force of the spring member 61 attached to the outer spool 52, and the bottom 5 of the outer spool 52
2a stops at a position where it contacts the spring receiving member 60 also serving as a stop member.

Therefore, the spool valve 14 is connected to the pressure difference between the control orifice 9 and the pressure in the first pressure chamber 15,
When the outer spool 52 moves to the second pressure chamber 16 side when the pressure in the pressure chamber 16 and the force obtained by adding the spring force of the control spring 17 to the pressure in the pressure chamber 16, the opening area of the drain passage 19 further increases. become.

Thus, the hydraulic oil supplied into the first pressure chamber 15 flows through the drain passage 19 whose opening area is increased by the movement of the outer spool 52 when the actuator does not require the hydraulic oil. It is returned to the pump suction side and the oil storage tank side not shown. 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.

The outer spool 52 is connected to the inner spool 5
By configuring the spool valve 50 with the dual structure of the inside and the outside, 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, regarding the structure in which the spring member 61 is disposed in the low-pressure chamber 56, this spring member is disposed between the inner spool 51 and the outer spool 52, and the inner and outer spools 51 and 52 are attached to each other in opposite directions. Because it is a force
It is also possible to arrange between the end face of the cylindrical portion 52a of the outer spool 52 and the flange portion 59a of the plug 59.

[0040]

As described above in detail, according to the present invention, the first pressure chamber into which the hydraulic oil is introduced through the spool valve receiving hole and the second pressure chamber into which the pressure after passing through the control orifice are introduced. A required flow rate of the hydraulic oil introduced into the first pressure chamber through a control orifice to a discharge passage, and a surplus flow rate corresponding to the required flow rate to a drain passage controlled to be opened and closed by movement of the spool valve. In a flow control valve adapted to be bypassed, the spool valve is fitted with a bottomed cylindrical outer spool having a through hole at the bottom, a large diameter portion inserted into the inner periphery of the cylindrical portion of the outer spool, and a through hole. An inner spool having a small-diameter portion to be inserted, the bottom of the outer spool facing the second pressure chamber, and an inner circumference of a cylindrical portion of the outer spool and a small-diameter portion of the inner spool. And the control spring acts on the inner spool, and further urges the inner spool toward the first pressure chamber between the inner spool and the outer spool, thereby forming the outer spool. Is attached to the second pressure chamber side, so that when the actuator is in a non-operating state and the required hydraulic oil pressure is low, unnecessary energy consumption of the pump can be suppressed. it can. 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 shows a high pressure in a first pressure chamber and a second pressure chamber;
It is sectional drawing which shows the state which the outer side spool moved to the 1st pressure chamber side.

FIG. 3 is a diagram showing flow control characteristics.

[Explanation of symbols]

 Reference Signs List 5 spool valve receiving hole 8 discharge passage 9 control orifice 15 first pressure chamber 16 second pressure chamber 17 control spring 19 drain passage 20 introduction passage 50 spool valve 51 inner spool 51a large diameter portion 51b small diameter portion 52 outer spool 52a cylindrical portion 52b Bottom 53 Through-hole 56 Low-pressure chamber 61 Spring member

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B62D 5/07 B62D 6/02

Claims (2)

(57) [Claims] A spool valve is slidably received in a spool valve receiving hole, a first pressure chamber and a second pressure chamber are defined in the spool valve receiving hole, and a control orifice is provided in the first pressure chamber. And a control spring for guiding the pressure of the discharge passage and biasing the spool valve toward the first pressure chamber in the second 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 controlled to be opened and closed by movement of the spool valve. The spool valve may be a bottomed cylindrical outer spool having a through hole at the bottom, an inner spool having a large diameter portion inserted into the inner periphery of the cylindrical portion of the outer spool, and an inner spool having a small diameter portion inserted into the through hole. The lower portion of the outer spool faces the second pressure chamber, and a low-pressure chamber is formed between the inner periphery of the cylindrical portion of the outer spool and the outer periphery of the small-diameter portion of the inner spool. A spring member is provided between the inner spool and the outer spool to actuate a spring, and to bias the inner spool toward the first pressure chamber and bias the outer spool toward the second pressure chamber. A flow control device characterized by the above-mentioned. 2. The flow control device according to claim 1, wherein the spring member is housed in the low-pressure chamber.