JPH10324259A - Power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain whistling noise without reducing valve characteristic, by providing a first supply hole with smaller diameter than that of a second supply hole in a control valve which is equipped with closing valves for closing between the first supply holes and discharge holes in its neutral position and an opening value for communicating between the second supply holes and the discharge holes. SOLUTION: A control valve 14 is equipped with a power cylinder 12 which power-assists steering operation with hydraulic fluid which is supplied from a pump 10 through the control valve 14, a first valve member 16 which forms plural recessed and projecting parts, first supply holes 21, delivering holes 23 on their both sides, and second supply hole 22, a second valve member 15 which forms discharge holes 24 adjacent to the plural recessed and projecting parts and the delivering holes 23, closing valves V5, V6 which close between the first supply holes 21 and discharge holes 24 in the neutral position, and opening valves V1, V2, V3, V4 which communicate between the second supply holes 22 and the discharge holes 24. In this control valve 14, diameter of each first supply hole 21 is smaller than that of each second supply hole 22, therefore, whistling noise is restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic power steering device used for automobiles and the like.

[0002]

2. Description of the Related Art A first conventional power steering device (Japanese Patent Laid-Open No.
127401), as shown in FIG. 3 and FIG. 11, when the rotary type control valve is neutral, the flow path between the pump P and the left and right cylinder chambers C is exceeded by the shoulder S on the first supply hole F side of the projection T. It is composed of a closed portion K that wraps and closes, and an open portion O that opens a flow path between the pump P and the return,
It was a center-closed valve that aimed at high rigidity by suppressing the rise in the differential pressure between the left and right cylinders at small steering angles.

A second conventional power steering device (Japanese Patent Laid-Open No.
32842) is a closed type in which the flow path between the pump P and the left and right cylinder chambers C is overlapped and closed by the shoulder S on the discharge hole E side of the projection T when the rotary type control valve is neutral as shown in FIG. This was a center closed valve which was constituted by a portion K and an open portion O which opened a flow path between the pump P and the return, suppressed an increase in the differential pressure between the left and right cylinders C at a small steering angle, and aimed at high rigidity.

[0004]

The above-mentioned conventional center closed valve is blocked by a closed portion K that overlaps when the valve is in a neutral position, and most of the flow rate flows to the open portion O. When the steering starts, the hydraulic oil discharged from the pump P starts to flow into the closed portion K after the closed portion K starts to open, but the opening area of the closed portion K suddenly increases at the point of switching from the overlap to the underlap. This causes a problem that the shoe noise increases due to the rapid flow to the closed portion K.

[0005] For this reason, in order to gradually change the flow rate change in the closed portion K, if the chamfer of the shoulder portion of the closed portion K is made shallow, the flow rate change is gradually changed and shoe noise is reduced. There is a problem that the characteristics are not satisfactory.

[0006] The present inventors have established a first valve communicating with a close valve.
By reducing the flow rate flowing through the supply hole as compared to the flow rate flowing through the second supply hole communicating with the open valve, it is possible to suppress the pressure acting on the close valve when steering starts and when the close valve starts opening. As a result of further research and development focusing on the technical idea of the present invention, the present invention has been achieved which achieves the object of suppressing shoe noise without sacrificing valve characteristics.

[0007]

According to a first aspect of the present invention, there is provided a power steering apparatus comprising: a first supply hole; a distribution hole on both sides of the first supply hole; a second supply hole; And a second valve member having a discharge hole formed adjacent to the distribution hole.
A control valve comprising a valve member, a close valve closing the first supply hole and the discharge hole at a neutral position, and an open valve communicating the second supply hole and the discharge hole. The first supply hole is formed to have a smaller diameter than the second supply hole.

[0008] In the power steering apparatus of the present invention (the second invention of the second aspect), in the first invention, the first valve member and the second valve member are provided with a plurality of concavo-convex portions facing each other. The convex portions formed and formed on the first valve member and the second valve member respectively have overlapping portions constituting a close valve between the first supply hole and the discharge hole at a neutral position. And an underlapping portion that constitutes an open valve between the second supply hole and the discharge hole.

According to a third aspect of the present invention, in the power steering apparatus of the second aspect, the overlapping portion is formed between the first supply hole and the distribution hole. Is what is being done.

According to a fourth aspect of the present invention, in the power steering apparatus of the second aspect, the overlapping portion is formed between the distribution hole and the discharge hole. Is what it is.

A power steering apparatus according to the present invention (fifth invention according to claim 5) is the power steering apparatus according to any of the first to fourth inventions, wherein the control valve is constituted by a rotary valve. is there.

[0012]

The power steering apparatus according to the first aspect of the present invention having the above-described structure, in the neutral position, includes the first supply hole formed in the first valve member and the second supply member formed in the second valve member. The close valve closes between the discharge hole and the first valve.
The open valve communicates between the second supply hole and the discharge hole formed in the valve member, and when the steering is performed and the close valve starts to open, it flows to the close valve through the first supply hole. Since the first supply hole is formed with a smaller diameter than the second supply hole, the flow of the close valve is suppressed and the flow gradually proceeds. Is produced.

[0013] In the power steering apparatus according to a second aspect of the present invention, in the first aspect, the first supply member is provided at a neutral position by a convex portion formed on each of the first valve member and the second valve member. Since the part constituting the close valve overlaps between the hole and the discharge hole, and the part constituting the open valve underlaps between the second supply hole and the discharge hole,
When steering and the overlapping part starts to open,
The gas flows to the overlapping portion through the first supply hole. However, since the first supply hole is formed with a smaller hole diameter than the second supply hole, the flow of the overlapping portion is suppressed and gradually. As a result, the shoe sound is suppressed without sacrificing the valve characteristics.

The power steering apparatus according to a third aspect of the present invention is the power steering apparatus according to the second aspect of the present invention, wherein the first power steering apparatus is provided at the neutral position.
When the overlapping portion formed between the supply hole and the distribution hole overlaps, and the portion constituting the open valve underlaps, when the steering starts to open the overlapping portion, Flow through the overlapping portion and the distribution hole via the first supply hole, but since the first supply hole is formed with a smaller hole diameter than the second supply hole, the flow of the overlapping portion is reduced. Since it is suppressed and flows gradually, there is an effect that the shoe noise is suppressed without sacrificing the valve characteristics.

In the power steering apparatus according to a fourth aspect of the present invention, in the second aspect, the overlapping portion formed between the distribution hole and the discharge hole overlaps at the neutral position. At the same time, since the portion constituting the open valve underlaps, when the steering is started and the overlapping portion starts to open, the first
Flow through the overlapping portion and the discharge hole via the supply hole, but since the first supply hole is formed with a smaller hole diameter than the second supply hole, the flow of the overlapping portion is suppressed. Since the fluid gradually flows, the effect of suppressing the shoe noise without sacrificing the valve characteristics is achieved.

In the power steering apparatus according to the fifth aspect of the present invention, since the control valve is a rotary valve in any one of the first to fourth aspects, the control valve and the power steering are provided. This has the effect of compacting the device.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention are described below.
This will be described with reference to the drawings.

(First Embodiment) As shown in FIGS. 1 to 8, a power steering device of the first embodiment
A power cylinder 12 for power-assisting the steering operation with hydraulic oil supplied from a control valve 14 through a plurality of uneven portions, a first supply hole 21 and both sides of the first supply hole 21. Distribution hole 23 and second supply hole 22
And a second valve member 15 having a plurality of concave and convex portions and a discharge hole 24 adjacent to the distribution hole 23, and the first supply hole 2 at a neutral position.
1 and the closing valve V that closes between the discharge holes 24
5, V6 and open valves V1, V2, V3, V4 for communicating between the second supply hole 22 and the discharge hole 24.
In the control valve 14 having the first supply hole 21
Is formed with a smaller hole diameter than the second supply hole 22.

As shown in FIGS. 1 to 3, the power steering apparatus according to the first embodiment includes a pump 10 driven by an automobile engine, a reservoir 11, a power cylinder 12 for power assisting a steering operation, A rotary control valve 14 that operates in response to the rotation of the steering wheel 13 and controls the throttle of the hydraulic oil supplied from the pump 10 to the power cylinder 12.

The pump 10 is provided with a known flow control valve (not shown) so as to maintain a constant flow supplied to the control valve 14.

As shown in an exploded view in FIG. 2, the control valve 14 is connected to a steering wheel 13 and rotates integrally with the valve shaft 15, and is disposed coaxially around the outer periphery of the valve shaft 15. The power cylinder 1
2, a valve body 16 connected to a steering cage (not shown) which is power assisted, a torsion bar 19 connecting the valve body 16 and the valve shaft 15 so as to be relatively rotatable, and a valve housing for accommodating them. (Not shown) and the like.

Each of the outer circumference of the valve shaft 15 as the second valve member and the inner circumference of the valve body 16 as the first valve member has a plurality of circles (8 in the first embodiment). ) Are formed respectively.

Between the valve shaft 15 and the valve body 16, two types of control units 17 and 18 (hereinafter referred to as a first control unit 17 and a second control unit 1) for restricting the operation oil.
8) are alternately formed at 90 ° intervals in the circumferential direction.

The first control unit 17 comprises four flow paths L1, L2, which are connected to the pump 10 and the reservoir 11, respectively.
It comprises a first bridge circuit C1 provided with variable apertures V1, V2, V3, V4 at L3, L4. These variable throttles V1, V2, V3, V4 are configured as center open valves shown in FIG. 4, and their opening areas are determined by the relative rotation angle (valve rotation angle) of the valve shaft 15 and the valve body 16. Accordingly, it changes as shown in a diagram A1 in FIG.

The second control unit 18 is connected in parallel to the first bridge circuit C 1 and has four flow paths respectively connected to the pump 10, the oil chambers 12 A and 12 B of the power cylinder 12, and the reservoir 11. L5, L6, L7, L8
And a second bridge circuit C2 provided with variable apertures V5, V6, V7, and V8.

Of the variable throttles, the variable throttles V5 and V6 connected to the pump 10 are configured as center close valves (close valves) as shown in FIG.
The variable apertures V7 and V8 connected to the reservoir 11 are
As shown in FIG. 4, it is configured as a center open valve (open valve).

The opening areas of the variable diaphragms V5 and V6 change as shown in a diagram A0 in FIG. 8 according to the relative rotation angle (valve rotation angle) between the valve shaft 15 and the valve body 16. The aperture areas of the apertures V7 and V8 change as shown in a diagram A1 in FIG. 8 according to the valve rotation angle.

As shown in FIGS. 1 and 2, a discharge hole 24 communicating with the reservoir 11 is formed at every other one of the plurality of recesses 15A on the outer periphery of the valve shaft 15,
In the concave portion 16A adjacent to the valve body 16 facing the concave portion 15A where the discharge hole 24 is not formed, a distribution hole 23 communicating with the oil chambers 12A and 12B of the power cylinder 12 is formed.

The convex portions 16B formed between the adjacent concave portions 16A in which the distribution holes 23 are formed, and in which the variable throttles V5 and V6 forming the center close valve are formed by overlapping portions 16BE at both ends. The variable throttles V1 and V2 forming a center open valve are formed by underlapping portions 16CE at both ends opposite to the concave portion 15A where the first supply hole 21 having a small diameter is formed and the discharge hole 24 is not formed. Convex part 1
The second supply hole 22 having a relatively large diameter is formed in 6C.

In the first embodiment, the first supply hole 21 and the second supply hole 22 communicate with the pump 10, and the diameter of the first supply hole 21 is the second supply hole. 22 is set to a quarter of the diameter.

In the power steering apparatus according to the first embodiment having the above-described structure, the constant-flow hydraulic oil discharged from the pump 10 is supplied to the first and second bridge circuits C1 and C2.
Around the neutral state of the steering,
The hydraulic fluid is not supplied to the power cylinder 12 because the variable throttles V5 and V6 of the bridge circuit C2 are closed as shown in FIG.
The two oil chambers 12A and 12B are connected to the reservoir 11 via the variable throttles V7 and V8, and are kept in a low pressure state.

Therefore, near the neutral position of the steering, no pressure difference is generated between the two oil chambers 12A and 12B of the power cylinder 12, so that the driver can be given a firm response.

In this state, the steering wheel 13 is rotated to rotate the valve shaft 15 with respect to the valve body 16, for example, clockwise (FIG. 2).
(Moving in the middle right direction), the opening area of each one of the variable diaphragms V2, V3 of the first bridge circuit C1 is enlarged, and the opening area of each of the other variable diaphragms V1, V4 is reduced.
The pressure of the pump 10 gradually increases.

On the other hand, the variable aperture V of the second bridge circuit C2
5, the closed state of V6 is maintained until the valve rotation angle becomes θ1, as shown in FIG.
Up to 1, the pressure difference between the two oil chambers 12A and 12B of the power cylinder 12 is maintained at zero.

When the valve rotation angle becomes larger than θ1, one variable throttle V6 of the second bridge circuit C2 starts to open as shown in FIG. 6, and the opening area gradually increases. The working oil is supplied to the chamber 12B. Also, as shown in FIG. 7, when an underlap state occurs, the aperture opening area increases rapidly.

In this case, the pressure in the cylinder oil chamber 12B is determined by the throttle areas of the variable throttles V1, V4 of the first bridge circuit C1 and the variable throttle V8 of the second bridge circuit C2. Accordingly, the differential pressure between the two oil chambers 12A and 12B of the power cylinder 12 increases, and the steering operation is assisted.

At this time, in the first embodiment, when the valve rotation angle exceeds θ1 due to the steering, the overlapping portion 16BE of the variable throttle V6 starts to open. Flows through the variable throttle V6 and the distribution hole through the first supply hole 2
1 is formed with a sufficiently smaller hole diameter than the second supply hole 22, the first supply hole 21 functions as a throttle for the flow of the hydraulic oil supplied from the pump 10. The flow of the overlapping portion 16BE constituting the variable throttle V6 is suppressed and gradually flows.
6 is prevented from flowing.

In the power steering apparatus according to the first embodiment having the above-described operation, the first supply hole 21 having a small diameter is provided with the pump 1.
In order to achieve a function as a throttle for the flow of the hydraulic oil supplied from 0, the flow of the variable throttle V6 is suppressed and gradually flows, and the shoe noise is reduced without sacrificing the conventional valve characteristics. Is produced.

That is, in the first embodiment, a sudden increase in the flow rate at the point where the variable throttle V6 switches from the overlap to the underlap is suppressed, and the shoe noise is reduced.

Therefore, the change in the flow rate to the open and close valves with respect to the gear inlet pressure can be reduced without substantially changing the valve characteristics (pressure loss at the time of neutrality).
The rise of the shoe noise can be prevented.

Further, the power steering apparatus of the first embodiment has an effect that the control valve and the power steering apparatus can be made compact because the control valve 14 is constituted by a rotary valve.

Further, the power steering device of the first embodiment is
Since only the first supply hole 21 is set to have a relatively small diameter with respect to the second supply hole 22, no new parts and devices are required, so that an increase in shoe noise can be prevented without increasing costs. It works.

(Second Embodiment) In the power steering apparatus of the second embodiment, the overlapping portion 16BE of the first embodiment is formed by the first supply hole 21 and the distribution hole 23.
However, the difference is that the overlapping portion 15AE is formed between the distribution hole 23 and the discharge hole 24 as shown in FIG. The following description focuses on the differences.

That is, the overlapping portion 15AE is formed at the shoulder of the concave portion 15A of the valve shaft 15 where the discharge hole 24 is formed, on the side of the concave portion 16A where the distribution hole 23 of the valve body 16 is formed. , Variable apertures V7 and V8.

In the power steering apparatus according to the second embodiment having the above-described configuration, in the neutral position, the overlapping portion 15AE formed between the distribution hole 23 and the discharge hole 24 overlaps, Since the portion constituting the open valve underlaps, when the steering is performed and the overlapping portion 15AE starts to open, the overlapping portion 1AE is opened via the first supply hole 21.
5AE and the discharge hole 24, but since the first supply hole 21 is formed with a smaller hole diameter than the second supply hole 22, the flow to the overlapping portion 15AE and the power cylinder 12 is suppressed. It gradually flows.

The power steering apparatus according to the second embodiment having the above-described operation is similar to the power steering apparatus according to the first embodiment.
1 functions as a throttle for the flow of the hydraulic oil supplied from the pump 10, so that the flows of the variable throttles V5 and V6 are suppressed and gradually flow,
This has the effect of suppressing shoe noise without sacrificing the conventional valve characteristics.

That is, in the second embodiment, since the diameter of the first supply hole 21 is reduced, a rapid increase in the flow rate of the hydraulic oil flowing into the power cylinder 12 is suppressed, that is, the left and right chambers 12 A, It is possible to suppress a sudden increase in the differential pressure of 12B, and consequently a sudden increase in the flow rate of hydraulic oil flowing from the power cylinder 12 to the reservoir 11.

The above-described embodiments are exemplarily described for explanation, and the present invention is not limited to these embodiments. Those skilled in the art will recognize from the claims, the detailed description of the invention, and the drawings. Modifications and additions are possible without departing from the technical idea of the present invention.

In the above embodiment, an example was described in which the close valve was completely overlapped and closed, but the present invention is not limited to such a case. Can be adopted.

In the above embodiment, an example in which the opening area of the first supply hole is made smaller than the opening area of the second supply hole has been described. However, the present invention is not limited thereto. As shown in FIG. 10, a mode in which a fixed throttle 31 is disposed in a passage 30 that communicates the pump 10 with the first supply hole 21 can be adopted.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a control valve in a power steering device according to a first embodiment of the present invention.

FIG. 2 is a development view in which a half circumference portion of the control valve according to the first embodiment is developed.

FIG. 3 is an overall view showing an overall configuration of the power steering device according to the first embodiment.

FIG. 4 shows a variable throttle V2 in the control valve according to the first embodiment.
And FIG. 5 is an enlarged view for explaining V1.

FIG. 5 shows a variable throttle V6 in the control valve according to the first embodiment.
FIG. 7 is an enlarged view for explaining a closed state of V5 and V5.

FIG. 6 shows a variable throttle V6 in the control valve according to the first embodiment.
FIG. 7 is an enlarged view for explaining a state where V5 and V5 are overlapped and open.

FIG. 7 shows a variable throttle V6 in the control valve according to the first embodiment.
FIG. 5 is an enlarged view for explaining a state of zero overlap of V5 and V5.

FIG. 8 is a diagram showing a relationship between a valve rotation angle and an opening area in a variable throttle of the control valve according to the first embodiment.

FIG. 9 is a developed view in which a half circumference portion of a control valve according to a second embodiment of the present invention is developed.

FIG. 10 is a developed view in which a half circumference portion of a control valve according to another embodiment of the present invention is developed.

FIG. 11 is a developed view in which a half circumference portion of a control valve in a conventional power steering device is developed.

FIG. 12 is a developed view in which a half circumference portion of a control valve in another conventional power steering device is developed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Pump 12 Power cylinder 14 Control valve 15 2nd valve member 16 1st valve member 21 1st supply hole 22 2nd supply hole 23 Distribution hole 24 Discharge hole V5, V6 Close valve V1, V2 Open valve

Claims (5)

[Claims] 1. A first valve member having a first supply hole, distribution holes on both sides of the first supply hole, and a second supply hole, and a first valve member having a discharge hole formed adjacent to the distribution hole. A control valve comprising a two-valve member, a close valve closing the first supply hole and the discharge hole at a neutral position, and an open valve communicating the second supply hole and the discharge hole. The power steering device according to claim 1, wherein the first supply hole has a smaller diameter than the second supply hole. 2. The first valve member and the second valve member according to claim 1, wherein the first valve member and the second valve member are formed with a plurality of concavo-convex portions facing each other, and are formed on the first valve member and the second valve member, respectively. The convex portion has an overlapping portion that forms a close valve between the first supply hole and the discharge hole at a neutral position, and forms an open valve between the second supply hole and the discharge hole. A power steering device characterized by having an underlapping portion. 3. The power steering device according to claim 2, wherein the overlapping portion is formed between the first supply hole and the distribution hole. 4. The power steering apparatus according to claim 2, wherein the overlapping portion is formed between the distribution hole and the discharge hole. 5. The power steering device according to claim 1, wherein the control valve includes a rotary valve.