JPH08332966A - Hydraulic control valve - Google Patents

Abstract

PURPOSE: To simplify the flow of return oil from the oil fed side and effectively damp torsional vibration between a valve body and a valve spool. CONSTITUTION: A valve spool 41 with sleeves 42a, 42b fittingly fixed to the outer periphery is fitted to the inside of a cylindrical valve body 40 in such a way as to be displaceable in the relative angle. An oil groove B formed on the outer peripheral surface of the valve spool 41 so as to receive return oil from the oil fed side is extended over fittingly fixed parts of the sleeves 42a, 42b so as to be communicated with an oil discharge chamber formed on one side of the valve body 40. An O-ring 6 serving as a vibration damping member is fitted around the outer peripheries of the sleeves 42a, 42b, and this O-ring 6 is brought into elastic contact with the valve body 40, the continuous surface outside of the oil groove formed area, so as to damp torsional vibration between the valve body 40 and valve spool 41.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary hydraulic control valve for controlling hydraulic pressure in accordance with relative angular displacement between a valve body and a valve spool which are coaxially generated, and more particularly,
The present invention relates to a hydraulic control valve used in a hydraulic power steering apparatus mounted on an automobile to control a hydraulic pressure supplied to a hydraulic actuator for assisting steering in accordance with a steering wheel operation.

[0002]

2. Description of the Related Art A hydraulic power steering apparatus assists steering by the generated force of a hydraulic actuator such as a double-acting hydraulic cylinder (power cylinder) arranged in a steering mechanism of an automobile, and a steering wheel (steering wheel). In order to obtain a comfortable steering feeling by reducing the labor load on the driver required for the operation of (1), both cylinder chambers (oil destinations) of the power cylinder and a hydraulic pump driven by an engine. A hydraulic control valve that controls the supply and discharge of hydraulic pressure according to the direction and magnitude of the steering torque applied to the steering wheel is arranged between the (hydraulic pressure source) and the oil tank (drainage destination) that stores the hydraulic oil. .

As the hydraulic control valve, a rotary hydraulic control valve which directly utilizes the rotation of the steering wheel is widely used. This coaxially connects an input shaft connected to the steering wheel and an output shaft connected to the steering mechanism via a small-diameter torsion bar, and inside the tubular valve body engaged with one connection end, A valve spool integrally formed at the other connecting end is fitted to the shaft so as to be rotatable relative to each other on the same axis.

On the inner peripheral surface of the valve body and the outer peripheral surface of the valve spool, a plurality of oil grooves extending in the axial direction are arranged side by side in a substantially equal arrangement in the circumferential direction. A plurality of throttle portions, which are arranged in a zigzag pattern in the circumferential direction on the circumference and change the throttle area according to the relative angular displacement, are formed between adjacent oil grooves. The hydraulic pressure is supplied from the hydraulic pump to any one of the oil grooves (oil supply groove), and oil grooves (distribution grooves) adjacent to both sides of the oil groove are provided in both oil chambers of the power cylinder. The oil grooves (discharging grooves) adjacent to each other on the other side of the distribution grooves are communicated with an oil tank which is an oil discharge destination.

Thus, when a steering torque is applied to the steered wheels, a relative angular displacement occurs between the input shaft and the output shaft, that is, between the valve body and the valve spool, accompanied by the torsion of the torsion bar. The squeezing area of the squeezing portion changes. As a result, the hydraulic pressure supplied from the hydraulic pump to the oil supply groove is introduced into the adjacent distribution grooves on the same side via the throttle portion on the side where the throttle area is increased, and one of the power cylinders communicating with the distribution groove is connected. Will be delivered to the oil chamber. As a result, the power cylinder generates an oil pressure according to the pressure difference between the power cylinder and the other oil chamber, and this oil pressure is applied to the steering mechanism as steering assist force to assist steering. On the other hand, at this time, the hydraulic oil is pushed out from the other oil chamber of the power cylinder and returns to the other distribution groove of the hydraulic control valve. After that, it is received in the drain groove and discharged to the oil tank that is the destination of the oil.

[0006] Generally, the return oil received in the discharge groove is discharged to the oil tank by utilizing the hollow portion formed inside the valve spool for inserting the torsion bar. It is performed through an oil drainage chamber formed on one side. That is, the discharge groove is formed by the first oil passage hole that penetrates the valve spool at the corresponding circumferential position, and the oil discharge chamber is located at a position outside the fitting region with the valve body. The return oil, which is respectively communicated with the hollow portion by the second oil passage hole passing through the spool and is received in the discharge groove, is collected in the hollow portion inside the valve spool through the first oil passage hole, Further, it is introduced into the oil discharge chamber through the second oil passage hole, and is discharged into the oil tank through the oil discharge pipe connected to the oil discharge chamber.

[0007]

In the hydraulic control valve as described above, the discharge groove for receiving the return oil from the oil destination is formed on the fitting circumference of the valve body and the valve spool. The oil discharge chamber for discharging the return oil is formed on one side of the valve body outside the fitting portion with the valve spool, and these are arranged in the axial direction outside the valve spool. Since they are in a state, it is rational that the two are communicated with each other on the fitting circumference of the valve body and the valve spool.

Focusing on this, for example, Japanese Patent Publication No. 2-414
No. 70, JP-A-4-266571, etc., the oil discharge chamber is formed by extending the discharge groove formed on the valve spool side or the valve body side in the axial direction beyond the fitting portion with the other. There is disclosed a hydraulic control valve which is communicated with the inside of the container and which is returned to the drain groove and is directly introduced into the drain chamber through an extension of the drain groove. According to this configuration, it is not necessary to form the oil passage hole that penetrates the peripheral wall of the valve spool for communication with the inner hollow portion, which can reduce the processing man-hour and the amount of oil discharged to the oil discharge chamber. The advantage is that the flow is simplified and stable operation of the hydraulic control valve is possible.

On the other hand, during the operation of the hydraulic control valve as described above, the pulsation of the hydraulic oil supplied from the hydraulic pump to the oil supply groove,
Due to fluctuations in the load applied to the output shaft, torsional vibration around the shaft center occurs between the valve body and the valve spool, and the throttle area of the throttle between the oil grooves fluctuates to control hydraulic pressure. When the hydraulic control valve used in the power steering device described above occurs, for example, there is a problem that the hydraulic pressure that feeds to the oil destination exhibits unstable behavior. The vibration of the power cylinder, which is the oil destination, propagates to the steered wheels, which causes the driver holding the steered wheels to feel uncomfortable.

As described in Japanese Patent Publication No. 1-21029 and Japanese Utility Model Publication No. 1-43977 disclosed by the applicant of the present invention, such torsional vibration is generated on the fitting circumference of the valve body and the valve spool. In addition, it is possible to effectively avoid this by a structure in which a vibration damping member made of an elastic material is interposed. The vibration damping member is, for example, a rubber O-ring wound around the outer circumference of the valve spool and elastically contacting the inner circumference of the valve body, and receives the hydraulic pressure introduced into the oil supply groove to one side to deform it, The valve body is pressed against the inner peripheral surface of the valve body over the entire circumference and functions as a damper that absorbs the above-mentioned torsional vibration.

However, in the hydraulic control valves disclosed in Japanese Patent Publication No. 2-41470 and Japanese Patent Application Laid-Open No. 4-266571, the discharge groove for receiving the return oil from the oil destination is extended in the axial direction. Therefore, the O-ring as a vibration damping member is not interposed between the valve body and the valve spool, and it is difficult to avoid the occurrence of the above-mentioned torsional vibration. The damping member may be a member that is discontinuous in the circumferential direction, but a discontinuous damping member that makes elastic contact with both the valve body and the valve spool that make relative angular displacement is stably interposed. It is difficult to wear it, and it is difficult to obtain a sufficient damping effect even if this intervention is done well.

The present invention has been made in view of the above circumstances, and aims to simplify the flow of return oil from the oil destination and to reduce the processing man-hours accordingly, and to realize the combination of the valve body and the valve spool. An object of the present invention is to provide a hydraulic control valve that is realized together with the purpose of effectively avoiding the occurrence of torsional vibration between the two.

[0013]

In a hydraulic control valve according to the present invention, a valve spool is fitted inside a tubular valve body so that relative angular displacement can be made on the same axis, and the valve spool is fitted on both sides. A plurality of lined oil grooves are arranged in a staggered manner to form a throttle portion that changes the throttle area according to the relative angular displacement between adjacent oil grooves in the circumferential direction, while the oil groove on the valve body side or the valve spool side is formed. Part of the valve body is extended in the axial direction to form a discharge groove communicating with an oil discharge chamber formed on one side of the valve body, and oil supply from a hydraulic pressure source is supplied to different destinations depending on the change of the throttle area. One of the valve body and the valve spool, wherein the oil is selectively fed to one of the two, the return oil from the other is received in the discharge groove, and the oil is discharged through the oil discharge chamber. The discharge groove is provided on the peripheral surface on the side provided with the discharge groove. A sleeve wherein is fitted while maintaining the communication between the oil discharge chamber, fits relatively rotatably on the other peripheral surface,
A vibration damping member interposed between the sleeve and the other peripheral surface and elastically contacting a portion of the peripheral surface where the oil groove is not formed is provided.

[0014]

According to the present invention, among the inner peripheral surface of the valve body and the outer peripheral surface of the valve spool which are fitted coaxially, one of the peripheral surfaces on the side having the discharge groove is provided with the respective discharge grooves and the valve body. The sleeve is fitted so as not to block the communication with the oil drain chamber on one side, and the return oil from the oil destination received in the drain groove is drained through the extension of the drain groove beyond the fitting part of the sleeve. Directly introduced into the room. Further, between the sleeve and the other peripheral surface, a vibration damping member is stably interposed in such a manner as to elastically contact a portion of the peripheral surface where no oil groove is formed, that is, a portion having a circumferential continuous surface. A sufficient damping effect is obtained against the torsional vibration generated between the valve body and the valve spool.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a schematic diagram showing the overall configuration of a rack and pinion type power steering apparatus.

The rack and pinion type steering mechanism includes a steering wheel 1
Pinion is attached to the lower end of the steering wheel axle 10 that is coaxially connected to the lower side of
11 is fixed, the pinion 11 is meshed with a middle portion of a rack shaft 12 extending in the left-right direction at the front of the vehicle body, and the rotation of the steering wheel 1 for steering is slid in the axial direction of the rack shaft 12. And a pair of left and right steering wheels (generally front wheels) connected to both ends of the rack shaft 12 via separate knuckle arms 1
It is configured to change the direction of 3 and 13 and perform steering.

The power steering apparatus for assisting the steering operation of the rack and pinion type steering mechanism with hydraulic pressure as described above serves as a power assisting cylinder S for steering assistance, which is formed in the middle of the rack shaft 12, and a hydraulic pressure source. A hydraulic pump P, an oil tank T serving as an oil discharge destination, and a hydraulic control valve 4 according to the present invention formed at the lower end portion of the steering wheel shaft 10 are provided, and these are connected to form a circulating oil passage as illustrated. The hydraulic pressure generated by the hydraulic pump P is sent to the power cylinder S by the operation of the hydraulic control valve 4 described later in response to the operation of the steering wheel 1, while the power cylinder S
The return oil from the oil tank T is circulated to the oil tank T, the hydraulic pressure (steering assisting force) generated by the power cylinder S by the feed hydraulic pressure is applied to the rack shaft 12, and the rack shaft 12 slides. It is configured to assist movement.

FIG. 2 is a vertical cross-sectional view of the main part of the power steering apparatus constructed as described above. In the figure, 2 is a hollow input shaft,
Similarly, 3 is a pinion shaft (output shaft), and these are
One end of each is abutted against the inside of the tubular valve housing 20 and is rotatably supported about the same axis. The abutting end (lower end) of the input shaft 2 is a cylindrical portion 3a that is continuously provided to the abutting end (upper end) of the pinion shaft 3.
Has a proper length and is rotatably supported, and these have a small diameter torsion bar 5 inserted in the hollow portion of the input shaft 2 and pin-coupled to the upper end portion of the pinion shaft 3. Are connected to each other by spline coupling.

The upper half of the input shaft 2 has a valve housing 20.
Of the steering wheel shaft 10 connected to the lower side of the steering wheel 1 at its protruding end. Further, the pinion 11 is formed in the lower half of the pinion shaft 3, and the pinion 11 is supported in a rack housing 21 that intersects with the lower portion of the valve housing 20.
It meshes with 12.

When the steering wheel 1 is rotated, the rotation of the steering wheel shaft 10 is added to the input shaft 2 and is further transmitted to the pinion shaft 3 via the torsion bar 5, which is below the input shaft 2. The rack shaft 12 meshing with the half-pinion 11 is converted into sliding in the axial direction for steering, and the sliding of the rack shaft 12 at this time is performed by steering wheels 13, 13 (see FIG. 1). Is performed against the reaction force from the road surface that contacts the ground, so that a relative angular displacement between the input shaft 2 and the pinion shaft 3 according to the steering torque applied to the steering wheel 1 with the torsion of the torsion bar 5 is generated. Occurs.

The hydraulic control valve 4 according to the present invention operates to control the hydraulic pressure to be fed to the power cylinder S by utilizing the relative angular displacement thus generated, and is provided inside the valve housing 20. A cylindrical valve body 40 held coaxially and rotatable, and a valve spool 41 inside the valve body 40.
Are fitted together via sleeves 42a, 42b integrally fitted to the outer circumference of the valve spool 41.

FIG. 3 is an enlarged sectional view of the main part of the hydraulic control valve 4. As shown in the figure, the valve body 40 is adapted to rotate integrally with the pinion shaft 3 by engaging the dowel pin 30 formed in the cylindrical portion 3a at the upper end of the pinion shaft 3 with its lower edge portion. 41 is a valve body in the middle of the input shaft 2 fitted inside the valve body 40.
It is integrally configured around the large-diameter portion 2a within a range that does not exceed the length of insertion into 40. The sleeves 42a, 42b are short ring-shaped members having an outer diameter substantially equal to the outer diameter of the large diameter portion 2a, and are press-fitted into the outside of the input shaft 2 from both sides, so that the large diameter portion 2a is inserted from both sides. It is integrally fixed to the position where it is held, and is inserted into the valve body 40 together with the valve spool 41. As a result, the valve body 40 and
Valve spool 41 and sleeve 42 integrated therewith
Between a and 42b, the relative angular displacement between the input shaft 2 and the pinion shaft 3 due to the operation of the steering wheel 1, that is, the relative angle according to the direction and magnitude of the steering torque applied to the steering wheel 1. Displacement occurs.

On the fitting peripheral surface of the valve body 40 and the valve spool 41 as described above, that is, on the inner peripheral surface of the former and the outer peripheral surface of the latter, a plurality of oil grooves are equally arranged in the circumferential direction. Has been formed. 4 and 5 are perspective views showing a manner of forming the oil groove on the outer peripheral surface of the valve spool 41. As shown in FIG. 4, four oil grooves A, A ... Having a depth not exceeding the radial thickness of the large diameter portion 2a are provided on the outer circumference of the valve spool 41 over the entire length of the large diameter portion 2a. They are formed so as to be evenly distributed in the circumferential direction, and the large diameter portion 2a is provided between these oil grooves A, A ...
Four oil grooves B, B, which are long and have a depth exceeding the thickness in the radial direction and which are extended to both sides of the large diameter portion 2a, are formed equidistantly in the circumferential direction.

On the outer peripheral surfaces of the sleeves 42a, 42b fitted on the outer periphery of the valve spool 41 as described above, annular grooves 43, 44 are provided around the center in the longitudinal direction, respectively. Separate concave grooves 45, 46 formed on the outer peripheral surfaces of 42a, 42b
Is connected to the one end face. As shown in FIG. 4, the sleeves 42a and 42b configured as described above are
The end faces of the communication sides of 45 and 46 are first, and the communication positions of these are aligned with the circumferential positions of any of the oil grooves A, A ... And press-fitted into the valve body 41. As shown in FIG. Is abutted on both end surfaces of the large diameter portion 2a, and is fixed to a position where the large diameter portion 2a is tightly held from both sides.

The long oil grooves B, B ... Formed on the outer peripheral surface of the valve spool 41 due to the fitting of the sleeves 42a, 42b as described above, on the outer peripheral side of the valve spool 41, have the length of the large diameter portion 2a. The length of the opening is limited to substantially the same length as the short oil grooves A, A ..., On the other hand, the oil grooves B, B. Sleeves on both sides of 42a, 42b
Of the oil grooves B, B ... Opened on both sides of the fitting portions of the sleeves 42a, 42b. Further, at this time, the annular grooves 43, 44 provided around the outer peripheral surfaces of the sleeves 42a, 42b are in communication with the short oil grooves A, A ... Through the respective concave grooves 45, 46. .

As shown in FIG. 3, the valve spool 41 formed by integrating the sleeves 42a and 42b as described above is a sleeve.
The fitting positions of 42a and 42b are fitted and inserted so as to be included in the length range of the valve body 40, and the hydraulic control valve 4 is configured with the valve body 40. On the inner peripheral surface of the valve body 40, eight oil grooves A, A ... And oil grooves B, B ... on the outer peripheral surface of the valve spool 41 are formed in the same number in the circumferential direction. In the valve body 40 and the valve spool 41, the respective oil grooves are arranged in a staggered manner in the circumferential direction, and a plurality of throttle portions that change the throttle area according to the relative angular displacement are formed between adjacent oil grooves. It is located in. At this time, the long oil grooves B, B ...
Communicates with both sides of the valve body 40 through openings on both sides of the sleeves 42a, 42b.

A rubber O-ring 6 as a vibration damping member is wound around one of the sleeves 42a, 42b, in the figure, an annular groove 43 formed on the outer circumference of the sleeve 42a. By being inserted into the valve body 40, the valve body 40 is elastically contacted with the inner peripheral surface of the valve body 40 at a position outside the area where the oil groove is formed.

The hydraulic pressure supplied from the hydraulic pump P is supplied to the hydraulic control valve 4 as described above through the pump port 22 opening to the outside of the valve housing 20, and the supplied hydraulic pressure is supplied to the valve body 40. .. are respectively introduced into the short oil grooves A, A .. Further, the oil groove on the valve body 40 side communicating with both sides of these oil grooves A, A ... Through the throttle portion is opened to the outside of the valve housing 20 by an oil guide hole penetrating a corresponding position of the valve body 40. Are connected to a pair of cylinder ports 23, 24,
The power cylinder S is connected by an oil pipe connected to these.
It is connected to both oil chambers separately.

Further, in the upper part of the valve body 40 inside the valve housing 20, there is formed an oil discharge chamber 25 connected to the oil tank T via a tank port 26 opening to the outside of the valve housing 20. The long oil grooves B, B, ... On the outer circumference of the valve spool 41 are extended to both sides of the sleeves 42a and 42b as described above, and communicated with the oil discharge chamber 25 through the extended portions toward the sleeve 42a. It is in a state.

The hydraulic pressure supplied from the hydraulic pump P to the hydraulic control valve 4 is introduced into the short oil grooves A, A ... (Oil supply grooves) on the outer circumference of the valve spool 41, and the throttle portions on both sides of these oil grooves are introduced. According to the change in the throttle area that occurs as described above, the oil is distributed to one of the oil grooves (distribution grooves) on the valve body 40 side that are adjacent to each other on both sides. Delivered to either. With this hydraulic pressure supply, the power cylinder S generates an oil pressure according to the pressure difference between the power cylinder S and the other oil chamber, and as described above, this oil pressure is applied to the rack shaft 12 as a steering assist force.

On the other hand, the hydraulic oil pushed out from the other oil chamber of the power cylinder S by this operation is the cylinder port.
It returns to the other distribution groove on the valve body 40 side through 24 or 23. On the other side of the distribution groove, long oil grooves B, B ... On the outer periphery of the valve spool 41 are communicated with each other within the length range of the large diameter portion 2a via a throttle portion, and flow back into the distribution groove. The return oil to be processed is received in the oil grooves B, B ... through the throttle portion. As described above, these oil grooves B, B ... Are communicated with the oil discharge chamber 25 on one side of the valve body 40 beyond the fitting portion of the sleeve 42a, and are received in the oil grooves B, B. The returned oil is introduced into the oil discharge chamber 25 via the respective extension portions and is discharged to the oil tank T via the tank port 26, as shown by the arrow in FIG.

The oil grooves B, B ... Are the other sleeves.
It is also extended to the side of 42b and communicates with the lower space of the valve body 40, and part of the return oil received in the oil grooves B, B ... Leaks into the lower space, and the bearing at the tip of the input shaft 2 is supported. The oil is introduced into the hollow portion of the input shaft 2 through a slight gap in the portion, and is introduced into the oil discharge chamber 25 through an oil passage hole 27 penetrating the peripheral wall of the input shaft 2 at a corresponding axial position. However, the amount of return oil that follows this route is small, and most of the return oil from the power cylinder S passes through the long oil grooves B, B, ... On the outer periphery of the valve spool 41 and exceeds the fitting portion of the sleeve 42a. Will follow the route directly discharged to the oil drainage chamber 25,
Due to the simplification of the discharge path, the return oil is discharged well, resulting in the valve body 40 and the valve spool.
The hydraulic control operation accompanying the angular displacement relative to 41 is stably performed.

On the other hand, the operation of such a hydraulic control valve 4 is as follows.
The O-ring 6 wound around the annular groove 43 on the outer circumference of the sleeve 42a is elastically contacted with the inner peripheral surface of the valve body 40. The O-ring 6 is, as described above, the valve body 40.
The annular groove 43, which is elastically contacted with the oil groove on the side where the formation of the oil groove is removed and on which the O-ring 6 is wound, communicates with the oil grooves A, A ... (Oil supply groove) on the outer circumference of the valve spool 41. Since the hydraulic pressure supplied from the hydraulic pump P is introduced, the O-ring 6
Receives the introduced hydraulic pressure to one side and is deformed into a mode in which it is pressed against the wall surface on the oil discharge chamber 25 side in the annular groove 43, and is strongly pressed against the inner peripheral surface of the valve body 40.

As a result, due to disturbances such as fluctuations in the hydraulic pressure supplied from the hydraulic pump P and fluctuations in the load applied to the pinion shaft 3 via the steered wheels 13, 13, the hydraulic control valve 4 is operated during operation. A sufficient damping effect can be obtained with respect to the torsional vibration about the axis generated between the body 40 and the valve spool 41, and the hydraulic control valve 4 can be operated stably.

At this time, the hydraulic pressure supplied from the hydraulic pump P is also introduced into the annular groove 44 on the outer circumference of the other sleeve 42b via the concave groove 46 on the same side. The hydraulic pressure introduced into the annular groove 44 acts evenly on the inner surface of the valve body 40,
The valve body 40 is made uniform in the radial direction in the circumferential direction and acts as a pressure balance groove for preventing pressure oil from leaking out from the fitting gap with the valve body 40. This action is similarly performed in the annular groove 43 around which the O-ring 6 is wound. The action as such a pressure valve groove is made possible by fitting the sleeves 42a, 42b to the outer side of the valve spool 41 and forming a circumferentially continuous fitting surface with the valve body 40. It is a thing.

In this embodiment, the valve spool
The 41 side oil grooves B, B ... Are used as drain oil grooves for receiving return oil, and these are extended in the axial direction to form a valve body 40.
Although it is communicated with the oil discharge chamber 25 formed on one side, the oil groove on the valve body 40 side can be used as a similar oil discharge groove, and in this case, the sleeves 42a and 42b are connected to the valve body.
Fitted on the 40 side, the sleeves 42a, 42b and the valve spool
An O-ring 6 for damping will be interposed between it and 41.

Further, in the present embodiment, the application example to the rack and pinion type power steering device has been described, but the application range of the hydraulic control valve according to the present invention is not limited to this, and a ball screw type or the like may be used. It is needless to say that the present invention can be applied to the power steering device of the type (1) and can be used for various applications for hydraulic control.

[0038]

As described above in detail, in the hydraulic control valve according to the present invention, the drainage on one side of the valve body, of the inner peripheral surface of the valve body and the outer peripheral surface of the valve spool, which are coaxially fitted together. Since the sleeve was fitted on one peripheral surface of the side provided with the discharge groove communicating with the oil chamber so as not to hinder the communication, the return oil from the oil destination received in the discharge groove will not fit the fitting portion of the sleeve. It is directly introduced into the oil discharge chamber through the discharge groove that exceeds, the return oil discharge path is simplified, and the hydraulic pressure control operation is stabilized, and in addition, between the sleeve and the other peripheral surface, Since the vibration damping member is interposed in such a manner as to make elastic contact with the portion where the oil groove is not formed on the surface, this vibration damping member elastically contacting the continuous surface in the circumferential direction produces the effect of torsional vibration generated between the valve body and the valve spool. Can be effectively damped, and the Etc. can be avoided constant operation in advance, the present invention provides excellent effects.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall configuration of a rack and pinion type power steering apparatus.

FIG. 2 is a vertical cross-sectional view of a main part of a power steering apparatus including a hydraulic control valve according to the present invention.

FIG. 3 is an enlarged sectional view of an essential part of a hydraulic control valve according to the present invention.

FIG. 4 is a perspective view showing a manner of forming an oil groove on the outer peripheral surface of the valve spool.

FIG. 5 is a perspective view showing a manner of forming an oil groove on the outer peripheral surface of the valve spool.

[Explanation of symbols]

 1 Steering Wheel 2 Input Shaft 2a Large Diameter Part 3 Pinion Shaft 4 Hydraulic Control Valve 5 Torsion Bar 6 O-ring 25 Oil Discharge Chamber 40 Valve Body 41 Valve Spool 42a Sleeve 42b Sleeve A Oil Groove B Oil Groove P Hydraulic Pump S Power Cylinder T Oil tank

Claims (1)

[Claims] 1. A valve spool having a cylindrical shape is fitted inside a valve body so as to be capable of relative angular displacement on the same axis, and a plurality of oil grooves arranged on the fitting circumference of the two are arranged in a staggered manner. A throttle portion that changes the throttle area according to the relative angular displacement is formed between oil grooves adjacent to each other in the direction, while a part of the oil groove on the valve body side or the valve spool side is extended in the axial direction to form a valve body. With a discharge groove communicating with the oil discharge chamber formed on one side, the oil supply from the hydraulic pressure source is selectively sent to one of different oil destinations according to the change in the throttle area,
In a hydraulic control valve configured to receive return oil from the other into the discharge groove and discharge the oil through the discharge chamber, in a peripheral surface of the valve body and the valve spool on a side including the discharge groove. A sleeve that is fitted while maintaining communication between the discharge groove and the oil discharge chamber, and is fitted to the other peripheral surface so as to be relatively rotatable, and is interposed between the sleeve and the other peripheral surface, A hydraulic control valve, comprising: a damping member that elastically contacts a portion of the peripheral surface where the oil groove is not formed.