JP3253239B2 - 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, it is generally desired that the power steering device be able to obtain sufficient steering assisting force when the vehicle is running at a low speed or when the vehicle is stopped, in other words, when the internal combustion engine is driven at a low rotation 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 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 is communicated with the low pressure side by a bypass valve, whereby the spool valve that controls the flow rate is moved, and the oil amount in the discharge passage is reduced. 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.

Another object of the present invention is to provide a flow control device capable of controlling the amount of oil supplied to an actuator.

[0010]

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 rate control device, the pressure in the second pressure chamber is introduced, and a control pressure chamber is provided between the control pressure chamber and the second pressure chamber, with one end face facing the second pressure chamber. A movable spring receiving member which abuts on the flow control spring and whose other end surface faces the control pressure chamber with an area larger than the area of the one end surface; and a biasing force of the movable spring receiving member toward the control pressure chamber. It is supplied with a spring member to provide further
Control means for controlling the movement of the movable spring receiving member toward the second pressure chamber is provided.

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, according to 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. The movement of the movable spring receiving member toward the second pressure chamber is controlled by the control means.

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 becomes 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 is the flow rate indicated by AB in FIG.

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 the control spring to set the control spring. Increase the load gradually. Accordingly, 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.

When the pressure in the control pressure chamber reaches a predetermined pressure, the movable spring receiving member moves to the second pressure chamber to maximize the set load of the control spring. The movement of the movable spring receiving member toward the second pressure chamber is controlled by the control means. In this state, the spool valve controls the flow rate in response to the differential pressure across the control spring and the control orifice, and the flow rate passing through the control orifice is controlled to the maximum flow rate.

The maximum flow rate supplied to the actuator can be changed depending on the moving position of the movable spring receiving member, and the movement of the movable spring receiving member is controlled by the control means. This control means can be achieved by, for example, an eccentric cam contacting the movable spring receiving member and a motor for rotating this eccentric cam, or by an electromagnetic solenoid. Therefore, when the movable spring receiving member is stopped and controlled by the control means at the position closest to the second pressure chamber, the flow rate passing through the control orifice is the flow rate shown by CD in FIG. When the movable spring receiving member is controlled to stop at a position slightly away from the second pressure chamber, the flow rate passing through the control orifice is as shown in FIG.
Is controlled to the flow rate indicated by EF.

Therefore, the operation of the control means is controlled by a driving state detection signal of the vehicle, such as the vehicle speed, for example.
By controlling the movement of the movable spring receiving member 37, when the vehicle is running at a low speed or stopped, the largest flow rate is supplied to the actuator of the power steering device to obtain a sufficient steering assist force, and the ground resistance of the wheels is reduced. When the vehicle is traveling at a small high speed, the supply flow rate can be reduced, and the steering assisting force can be reduced to ensure steering stability. Since the maximum flow rate supplied to the actuator can be variably controlled to an arbitrary flow rate by the control means, it can be controlled to an optimum flow rate according to the vehicle speed.

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. Accordingly, the work amount 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 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. A diametric through hole 13 communicating with the passage 10 is provided at the opening end of the passage 10.

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 of the passage 21 is closed. 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 drilled 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 an axial position of the spool valve housing hole 5. Reference numeral 37 denotes a movable spring receiving member disposed between the control pressure chamber 36 and the second pressure chamber 16. The movable spring receiving member 37 includes a cylindrical portion 38 and a flange 39 having a larger diameter than the cylindrical portion 38.
Is inserted into the second pressure chamber 16, one end surface 40 of the cylindrical portion 38 side faces the second pressure chamber 16 and abuts on the flow rate control spring 17, and the flange portion 39 is inside 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. A passage 42 penetrates 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 provided in the control pressure chamber 36.
The movable spring receiving member 37 is urged toward the control pressure chamber 36 in a spring member accommodating chamber 44 formed between the bottom surface of the second pressure chamber 16 and the flange 39.

Numeral 45 denotes control means for controlling the movement of the movable spring receiving member 37 toward the second pressure chamber 16. The control means 45 projects into the second pressure chamber 16 and controls the movable spring receiving member 37. Eccentric cam 46 with which the tip of cylindrical portion 38 contacts
And a step motor 47 for rotatingly driving a rotary shaft 46a to which the eccentric cam 46 is attached. As shown in FIG. 5, the eccentric cam 46 is a circular cam eccentrically attached to the rotating shaft 46a. The rotation of the step motor 47 of the control means 44 is controlled by a vehicle speed signal.

The inside of the spring member accommodating chamber 44 is connected to the drain passage 1 through a pressure-sensitive orifice 48 and an oblique hole 49.
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 connector 7.
Is guided to the discharge passage 8 through the through hole 13, the passage 10 and the orifice 9.

At this time, under normal conditions, 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 pump discharge oil amount 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 orifice 9, and based on the differential pressure across the orifice 9. As a result, 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 oil storage tank (not shown).

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. 2. The control spring 17 is supported at a position where it contacts the eccentric cam 46 projecting into the pressure chamber 16 (see FIG. 2).
Therefore, the spool valve 14 is provided with the movable spring receiving member 37.
At the position moved toward the second pressure chamber 16, and the control spring 17 supported by the movable spring receiving member 37.
It moves by balancing the force obtained by adding the pressure in the second pressure chamber 16 to the spring force of (mounting length L2) and the force generated by the pressure in the first pressure chamber 15, thereby controlling the flow rate.

In this case, the movable spring receiving member 37
Is stopped in contact with the eccentric cam 46 of the control means 45. That is, the movement to the second pressure chamber 16 side is
5. The operation of the control means 45 is controlled by the vehicle speed. When the vehicle speed is high, the eccentric cam 46 is moved to the position shown in FIG. 3 by the step motor 47, and the movable spring receiving member 37 is slightly separated from the second pressure chamber 16. Stop at the position. As a result, the spool valve 14 has a force obtained by adding the pressure in the second pressure chamber 16 to the spring force of the control spring 17 (mounting length L3) supported by the movable spring receiving member 37, and the first pressure chamber 1
It moves in balance with the force due to the pressure in 5 and controls the flow rate. The control flow rate guided to the discharge passage 8 is smaller than the state shown in FIG. And the flow rate is limited to the flow rate according to the vehicle speed.

As described above, by controlling the operation of the control means 45 by the vehicle speed signal and controlling the movement of the movable spring receiving member 37, when the vehicle is running at a low speed or stopped, the maximum flow rate of the power steering device is increased. Supply to the actuator to get enough steering assist,
During high-speed traveling with small ground contact resistance of the wheels, the supply flow rate can be reduced to reduce the steering assisting force and ensure the steering stability. The maximum flow rate supplied to the actuator can be variably controlled to an arbitrary flow rate by the control means 45, so that it can be controlled to an optimum flow rate according to the vehicle speed.

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 because 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 discharge passage 8
The pressure in the control pressure chamber 36, which is led through the second pressure chamber 16, is reduced. 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 projection 50 of the movable spring receiving member 37 abuts on the plug 4. When the movable spring receiving member 37 moves in a direction away from the second pressure chamber 16, the movable spring receiving member 3
Control spring 1 contracted between spool valve 7 and spool valve 14
7 becomes L1 (see FIG. 1) and the control pressure chamber 3
6 will be increased compared to the attachment length L2 or L3 (see FIG. 2 or FIG. 3) when the pressure inside is high.

Therefore, the spool valve 14 which moves by the balance between the differential pressure across the control orifice 9, ie, 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.

As a result, the hydraulic oil supplied into the first pressure chamber 15 is supplied to the drain passage 1 having an increased opening area when the actuator does not need 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 that guides the pressure in the second pressure chamber 16 to the control pressure chamber 36 is formed in the movable spring receiving member 37, a passage may be formed in the housing 1 instead.

[0044]

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. Further, a flow control valve capable of easily controlling the maximum supply oil amount supplied to the actuator 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 by a control means.

FIG. 3 is a cross-sectional view showing a state in which the pressure in the discharge passage is high and the movable spring receiving member is controlled to stop at a position slightly away from the second pressure chamber by the control means.

FIG. 4 is a diagram showing flow control characteristics.

FIG. 5 is an explanatory diagram of an eccentric cam of a control means.

DESCRIPTION OF SYMBOLS 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 Introductory passage 36 Control pressure chamber 37 Movable spring receiving member 40 One end face 41 Other end surface 43 Spring member 45 Control means

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-8-276855 (JP, A) JP-A-6-8840 (JP, A) JP-A-56-124560 (JP, A) JP-A-5- 85388 (JP, A) Japanese Utility Model Showa 51-11653 (JP, U) Japanese Utility Model Hei 6-65158 (JP, U) Japanese Utility Model Utility Model 5-92050 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) B62D 5/06-5/30 B62D 6/00-6/06

Claims (4)

(57) [Claims] A spool valve is slidably housed in a spool valve housing hole, a first pressure chamber and a second pressure chamber are defined in the spool valve housing hole, 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 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. 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. A control pressure chamber into which the pressure of the second pressure chamber is introduced; one end face between the control pressure chamber and the second pressure chamber;
A movable spring receiving member that faces the pressure chamber and contacts the flow rate control spring, the other end face of which has an area larger than the area of the one end face and faces the control pressure chamber is provided. A flow control device, further comprising a spring member for applying a biasing force toward the chamber, and a control means for controlling the movement of the operating spring receiving member toward the second pressure chamber. 2. The flow control device according to claim 1, wherein the control means includes an eccentric cam with which the movable spring receiving member contacts, and a motor for driving the eccentric cam to rotate. 3. The flow control device according to claim 2, wherein said motor is a step motor. Wherein said motor is controlled to rotate by the vehicle speed signal, claim 2 or claim 3 flow controller according.