JPH1067333A - Hydraulic power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic power steering device which does not vary in steering characteristics, which can easily be assembled, the weight of which can be reduced, which is free of abnormal noises, which can be improved in the yield, and which can be enhanced in the degree of freedom in the electric/ magnetic design. SOLUTION: A first cylindrical valve member is connected to or integrated into one body with an output shaft, which is connected to an input shaft 2 elastically and in a relatively rotatable manner, in an equally movable and rotatable manner. A second cylindrical valve member 25, which is inserted into the first valve member in a relatively rotatable manner, is integrated into one body with the periphery of the input shaft 2. By changing the opening of a throttled part between an edge along the axial direction of a recessed part on the first valve member side and an edge along the axial direction of a recessed part of the second valve member side, the hydraulic pressure acting on a hydraulic actuator for generating auxiliary steering power can be controlled. In this case, the second valve member 25 should be made of resin.

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 apparatus for controlling a hydraulic pressure acting on a hydraulic actuator for generating a steering assist force by a rotary hydraulic control valve.

[0002]

2. Description of the Related Art An input shaft, an output shaft elastically connected to the input shaft via an elastic member such as a torsion bar so as to be relatively rotatable, and connected or integrated with the output shaft so as to be rotatable together therewith. Conventionally, a hydraulic power steering device including a cylindrical first valve member and a cylindrical second valve member inserted into the first valve member so as to be relatively rotatable and integrated with the outer periphery of the input shaft is conventionally used. Have been. The inner periphery of the first valve member and the second
A plurality of recesses are formed on the outer periphery of the valve member at intervals in the circumferential direction, and between the edge along the axial direction of the first valve member-side recess and the edge along the axial direction of the second valve member-side recess. Is a throttle that communicates with the pressure oil supply pump, the hydraulic actuator for generating steering assist force, and the tank, and the opening changes according to the relative rotation of the two valve members. The hydraulic pressure acting on the hydraulic actuator for generating auxiliary force is controlled.

In the hydraulic power steering apparatus as described above, in order to obtain desired steering characteristics, a plurality of recesses in each valve member are precisely processed so that an arrangement pitch becomes uniform, and each throttle section is formed. It is necessary to precisely grind the chamfers at the axial edges of the concave portions constituting the above-mentioned method so that the chamfers have a uniform shape. However, if the processing or polishing is limited to cutting or polishing using a hob or milling cutter, it is necessary to form each recess individually, making it difficult to equalize the arrangement pitch and chamfer shape, and to improve the steering characteristics. There was a quality problem such as variation in the quality. Further, if the second valve member is formed integrally with the input shaft, processing such as quenching processing cannot be performed only on the second valve member, and there is a problem that the processing steps become complicated.

Therefore, the second valve member is constituted by a metal tubular member which is rotatably inserted into the first valve member and press-fitted into the outer periphery of the input shaft so as to be rotatable therewith. It has been proposed that the first valve member be composed of a metal cylindrical outer peripheral member and a metal cylindrical inner peripheral member press-fitted on the inner peripheral side of the outer peripheral member (Japanese Patent Laid-Open No. 6-99825). Reference). As a result, each recess formed in each valve member can be formed at once from a sheet metal material or a pipe material by press working using a punching die, and the arrangement pitch and chamfer shape can be easily and accurately uniform. Can be.

[0005]

In the conventional hydraulic power steering apparatus as described above, each valve member is made of metal, and its weight contributes to an increase in the weight of the entire apparatus.

There is a problem that the second valve member vibrates with respect to the first valve member due to the pulsation of the pressure oil supplied from the pump, and the two valve members come into contact with each other to generate an abnormal sound.

When the second valve member is press-fitted into the input shaft, if the second valve member has a poor quality at the time of product inspection, the input shaft having no problem must be discarded, which is one of the causes of lowering the yield. Has become.

Since the first valve member and the second valve member are made of metal, they cannot be electrically and magnetically insulated from each other. This is a design limitation when configuring.

In the hydraulic power steering apparatus as described above, in order to recirculate the pressure oil from the concave portion on the second valve member side to the tank, grooves extending axially outward from both ends of the concave portion on the second valve member side are formed. The pressure oil return channel is formed by forming the groove (Japanese Patent Application Laid-Open No. 54-1979).
-64334). This eliminates the need to process the flow path that constitutes the pressure oil return flow path in the input shaft, and reduces the number of processing steps. However, when the second valve member is constituted by a metallic tubular member press-fitted to the outer periphery of the input shaft, if both ends of such a groove are opened at both ends of the second valve member, the second valve member may be partially closed. And cannot be press-fitted into the input shaft and fixed. In addition, if the wall thickness and the axial dimension of the tubular member are increased so as not to be divided into a plurality of portions, the size of the device increases.

An object of the present invention is to provide a hydraulic power steering device that can solve the above-mentioned problem.

[0011]

SUMMARY OF THE INVENTION The present invention provides an input shaft, an output shaft elastically and relatively rotatably connected to the input shaft, and a cylinder which is rotatably connected or integrated with the output shaft. A first valve member, and a cylindrical second valve member inserted into the first valve member so as to be relatively rotatable and integrated with an outer periphery of the input shaft, and an inner periphery of the first valve member. A plurality of recesses are formed on the outer circumference of the second valve member at intervals in the circumferential direction.
A throttle that communicates with a pump for supplying pressure oil, a hydraulic actuator for generating a steering assist force, and a tank, and has an opening that changes according to the relative rotation of both valve members, between an edge along the axial direction of the concave portion on the valve member side. In a hydraulic power steering device capable of controlling a hydraulic pressure acting on a hydraulic actuator for generating a steering assist force by a change in the opening degree of the throttle portion, the second valve member is made of synthetic resin. I do.

According to the present invention, the respective recesses formed in the second valve member can be molded at once using a molding die, and the arrangement pitch and the chamfer shape can be easily and accurately uniform. it can. By making the second valve member made of a synthetic resin, it is possible to reduce the weight of the entire device as compared with a conventional one made of metal. Also, even if the first valve member and the second valve member collide, the second valve member made of synthetic resin
Since the valve member is more easily deformed elastically than the metal member and can be made more flexible, abnormal sound generation due to contact with the first valve member can be prevented by vibration absorption. Also, since the second valve member made of synthetic resin can have a lower melting point than that made of metal, even if the second valve member has poor quality during product inspection, it can be heated and melted or burned to improve quality. A problem-free input shaft can be reused, and the yield can be improved. In addition, since the second valve member is made of a synthetic resin, it is possible to electrically and magnetically insulate the second valve member from the first valve member, so that the degree of freedom in design can be increased.

[0013] The second valve member is preferably divided into a plurality of grooves along the axial direction that are open at both ends in the axial direction, and the grooves form a pressure oil return flow path between the throttle portion and the tank. . Since the second valve member is made of a synthetic resin, the groove along the axial direction is formed so as to open at both ends in the axial direction, so that the second valve member can be easily fixed to the input shaft even if divided into a plurality of portions. For example, when molding a second valve member by injecting a synthetic resin material into a mold, the input shaft is inserted into the mold and insert molding is performed to fix the second valve member to the input shaft. it can. Thereby, the pressure oil return flow path is formed by the groove along the axial direction without increasing the thickness and the axial dimension of the second valve member for fixing to the input shaft, that is, without increasing the size of the device. Can be configured.

The second valve member is insert-molded by supplying the synthetic resin material into a molding die into which the input shaft is inserted, so that the outer periphery of the input shaft is formed with irregularities into which the synthetic resin material enters. Is preferred. Thereby, the second valve member made of synthetic resin can be firmly fixed to the input shaft.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.

A rack and pinion type hydraulic power steering device 1 shown in FIG. 1 has a metal input shaft 2 connected to a steering wheel (not shown), and an elastic member connected to the input shaft 2 via a torsion bar (elastic member) 3. And a metal output shaft 4 which is connected so as to be relatively rotatable. The torsion bar 3 is connected to the input shaft 2 via a pin 5 and to the output shaft 4 via a serration 6. Its output shaft 4
A rack 8 meshing with the pinion 7 is connected to steering wheels (not shown). The input shaft 2 is supported by a metal valve housing 10 a via a bearing 9, and is supported by a bush 11 on the inner periphery of a concave portion 4 a formed at one end of the output shaft 4. The output shaft 4 is supported by a metal rack housing 10b via bearings 12 and 13. As a result, the rotation of the input shaft 2 due to the steering is transmitted to the pinion 7 via the torsion bar 3, and the rack 8 moves in the vehicle width direction, and the wheels are steered by the movement of the rack 8. Note that oil seals 14, 15 are provided between the input / output shafts 2, 4 and the valve housing 10a. A support yoke 16 for supporting the rack 8 is provided.
The support yoke 16 is pressed against the rack 8 by the elasticity of the spring 17.

A hydraulic cylinder 18 is provided as a hydraulic actuator for applying a steering assist force. The hydraulic cylinder 18 includes a cylinder tube formed by a rack housing 10b and a piston 20 formed integrally with the rack 8, and a pair of oil chambers 21 and 22 partitioned by the piston 20 are formed. A rotary hydraulic control valve 23 is connected to each of the oil chambers 21 and 22.

The control valve 23 is made of a cylindrical first valve member 24, and is made of a cylindrical synthetic resin which is inserted into the first valve member 24 so as to be relatively rotatable and integrated with the outer periphery of the input shaft 2. A second valve member 25.

As shown in FIG. 2, the first valve member 24 has a cylindrical outer peripheral member 24a and a cylindrical inner peripheral member 24b integrated with the inner peripheral side of the outer peripheral member 24a. The output shaft 4 is rotatably connected to the output shaft 4 via a pin 26. The inner peripheral member 24b may be made of metal or synthetic resin. The inner peripheral member 24b is attached to the outer peripheral member 24a,
For example, the outer peripheral member 24 is press-fitted or made of a synthetic resin.
a is integrated by insert molding in a molding die into which a is inserted. In the case of insert molding, it is preferable that irregularities such as knurls into which the synthetic resin material enters are formed on the inner periphery of the outer peripheral member 24a, thereby firmly fixing the inner peripheral member 24b to the outer peripheral member 24a. it can.

The second valve member 25 is connected to the input shaft 2.
And rotates with the input shaft 2 by being press-fitted into the outer periphery of the input shaft 2.

When the torsion bar 3 is elastically twisted according to the steering resistance, the two valve members 24 and 25 elastically rotate relative to each other according to the steering resistance.

As shown in FIG. 3, a plurality of concave portions along the axial direction are formed on the inner periphery of the first valve member 24 and the outer periphery of the second valve member 25 at equal intervals in the circumferential direction. The first valve member-side concave portions are provided with four right steering concave portions 27 located at regular intervals in the circumferential direction, and four right steering concave portions 27 located at regular intervals in the circumferential direction.
And two left steering recesses 28. The recesses on the second valve member side are provided with four concave portions 29 for supplying pressure oil which are located at regular intervals in the circumferential direction, and four concave portions located at regular intervals in the circumferential direction.
And one pressure oil discharge recess 30. Each right steering recess 27 and each left steering recess 28 are alternately arranged in the circumferential direction, and each pressure oil supply recess 29 and each pressure oil discharge recess 30 are alternately arranged in the circumferential direction. As shown in FIG. 1, each right steering recess 27 is provided with one oil of the hydraulic cylinder 18 via a first flow path 31 formed in the first valve member 24 and a first port 32 formed in the valve housing 10a. Room 2
1, each left steering recess 28 is provided with a first valve member 24.
Flow path 33 and valve housing 10 formed in
a through the second port 34 formed in the hydraulic cylinder 18
To the other oil chamber 22. Each pressure oil supply recess 29 is
As shown in FIG. 1, the fluid flows to a pump 37 through a third flow path 35 formed in the first valve member 24 and an inlet port 36 formed in the valve housing 10a. Each of the recesses 30 for discharging pressure oil has a first discharge path 38 formed in the second valve member 25, a passage 47 between the input shaft 2 and the inner and outer circumferences of the torsion bar 3, and a second discharge path 3 formed in the input shaft 2.
9, communicates with the tank 41 via a pressure oil return flow path formed by an axially outer space of the first valve member 24 and a discharge port 40 formed in the valve housing 10a. Thus, the pump 37, the tank 41, and the oil chambers 21 and 22 of the hydraulic cylinder 18 are connected to the first valve member 24 and the second
It communicates via an inter-valve flow path 42 between the inner and outer circumferences of the valve member 25. The inner periphery of the first valve member 24 and the second valve member 2
In the inter-valve flow path 42 between the outer periphery of the first valve member 5 and the axial portion of the second valve member-side concave portion, the two valve members 24 are provided. , 25, the apertures of which are changed by the relative rotation. The respective axial edges of the second valve member side concave portions 29, 30 are chamfered. Each aperture section A,
B, C, and D communicate with the pump 37, the tank 41, and the respective oil chambers 21, 22 of the hydraulic cylinder 18, and each of the throttle portions A,
The hydraulic pressure acting on the hydraulic cylinder 18 is controlled by the change in the opening degree of B, C, and D.

FIG. 3 shows both valve members 24 in a straight traveling state.
25. In this state, the pressure oil supply recess 29 and the pressure oil discharge recess 30 communicate with each other through all the throttle portions A, B, C, and D. The supplied pressure oil is directly returned to the tank 41 and no steering assist force is generated. When the vehicle is steered to the right from the straight traveling state, the torsion bar 3 is twisted in accordance with the steering torque, and the two valve members 24,
25 relatively rotates. As a result, the opening degree of the throttle portion A between each right steering recess 27 and each pressure oil supply recess 29 and the throttle portion B between each left steering recess 28 and each pressure oil discharge recess 30 are formed. The opening degree increases, and the opening degree of the throttle portion C between each left steering recess 28 and each pressure oil supply recess 29 and the throttle between each right steering recess 27 and each pressure oil discharge recess 30. The opening degree of the portion D is reduced. As a result, pressure oil is supplied from the pump 37 to one oil chamber 21 of the hydraulic cylinder 18, and the pressure oil is recirculated from the other oil chamber 22 of the hydraulic cylinder 18 to the tank 41, and the steering assist force to the right of the vehicle is provided. Acts on the rack 8. When steered to the left from the straight running state, each of the throttle portions A, B,
Since the opening degrees of C and D change oppositely to the case of steering to the right, the steering assisting force of the vehicle to the left acts on the rack 8.

As shown in FIGS. 4 and 5, (1) and (2), and FIGS. 6 (1) and (2), the second valve member side recess 2
9 and 30 are configured by through holes penetrating the second valve member 25. The second valve member 25 includes, for example,
It is molded by injection molding, with each recess 29, 30 being molded together with the chamfer at the axial edge.

In order to restrict the relative rotation between the input shaft 2 and the output shaft 4 within a certain range and to prevent the torsion bar 3 from being damaged, a first restricting portion 61 is provided on the input shaft 2.
Are formed, and the second regulating portion 62 is formed on the output shaft 4. The first restricting portion 61 is formed by a pair of parallel flat surfaces formed on the input shaft 2 along the axial direction. The first restricting portion 61 is inserted into the concave portion 4 a formed at one end of the output shaft 4. As shown in FIG. 7, a part of the inner peripheral surface of the concave portion 4 a of the output shaft 4 has a plurality of flat surfaces facing the first restricting portion 61,
Each flat surface serves as a second restricting portion 62. The first regulation part 6
When the first and second restricting portions 62 are in contact with each other, the relative rotation between the input shaft 2 and the output shaft 4 is restricted to a certain range.

According to the first embodiment, the respective recesses formed in the second valve member 25 can be formed at once by using a forming die, so that the arrangement pitch and the chamfer shape can be easily and accurately determined. It can be uniform. Also, the first
Since each concave portion formed in the valve member 24 can be formed at once from a sheet metal material or a pipe material by press working using a punching die, the arrangement pitch and the chamfer shape can be easily and accurately made uniform. . When the first valve member 24 is formed of a sheet metal material, each concave portion is formed into a tubular shape by welding after punching. By making the second valve member 25 made of a synthetic resin, it is possible to reduce the weight of the entire device as compared with the conventional one made of metal. Further, even if the first valve member 24 and the second valve member 25 collide, the second valve member 25 made of synthetic resin is more easily elastically deformed than the metal one and can be made more flexible. Generation of abnormal sound due to contact with the one valve member 24 can be prevented by vibration absorption. Also, since the second valve member 25 made of synthetic resin can have a lower melting point than that made of metal,
Even if the second valve member 25 has poor quality at the time of product inspection, the input shaft 2 having no quality problem can be reused by heating and melting or burning, and the yield can be improved. Further, since the second valve member 25 is made of a synthetic resin, it is possible to electrically and magnetically insulate the second valve member 25 from the first valve member 24, so that the degree of freedom in design can be increased.

A second embodiment of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment are denoted by the same reference numerals.

The rack and pinion hydraulic power steering apparatus 1 'of the second embodiment has an input shaft 2 connected to a steering wheel (not shown), and a torsion bar (elastic member) 3 inserted through the input shaft 2.
And an output shaft 4 elastically and relatively rotatably connected to the input shaft 2 via the torsion bar 3. One end of the torsion bar 3 is connected to the input shaft 2 via a pin 5, and the other end is a serration 6.
And the output shaft 4. A pinion 7 is formed on the output shaft 4, and a rack 8 meshing with the pinion 7 is connected to steering wheels (not shown).
One end of the input shaft 2 is supported by a valve housing 10a via a bearing 9, and the output shaft 4 is supported by a rack housing 10b via bearings 12 and 13. The difference between the inside diameter of the other end of the input shaft 2 and the outside diameter of the other end of the torsion bar 3 is made small, whereby the misalignment between the input shaft 2, the output shaft 4 and the torsion bar 3 is reduced. Has been prevented. As a result, the rotation of the input shaft 2 due to the steering is transmitted to the pinion 7 via the torsion bar 3, and the rack 8 moves in the vehicle width direction, and the wheels are steered by the movement of the rack 8. Note that oil seals 14, 15 are provided between the input / output shafts 2, 4 and the valve housing 10a. A support yoke 16 for supporting the rack 8 is provided.
The support yoke 16 is pressed against the rack 8 by the elasticity of the spring 17.

A hydraulic cylinder 18 is provided as a hydraulic actuator for applying a steering assist force. The hydraulic cylinder 18 includes a cylinder tube formed by a rack housing 10b and a piston 20 formed integrally with the rack 8, and a pair of oil chambers 21 and 22 partitioned by the piston 20 are formed. A rotary hydraulic control valve 23 is connected to each of the oil chambers 21 and 22.

The control valve 23 includes a first cylindrical valve member 24 and a second cylindrical synthetic resin valve member 25 rotatably inserted into the first valve member 24.
The second valve member 25 rotates together with the input shaft 2 by being integrated with the outer periphery of the input shaft 2.

As shown in FIG. 9, the first valve member 24 has a cylindrical outer peripheral member 24a and a cylindrical inner peripheral member 24b integrated with the inner peripheral side of the outer peripheral member 24a. As shown in FIG. 8, the output shaft 4 is rotatably connected to the output shaft 4 via a pin 26. The inner peripheral member 24b may be made of metal or synthetic resin. The inner peripheral member 24b is
For example, the outer peripheral member 24a
The synthetic resin material is supplied into the molding die into which is inserted, so that the molding is integrated with the outer peripheral member 24a by insert molding. In the case of insert molding, it is preferable that irregularities such as knurls into which the synthetic resin material enters are formed on the inner periphery of the outer peripheral member 24a, whereby the inner peripheral member 24b can be firmly fixed to the outer peripheral member 24a. .

The second valve member 25 is insert-molded by supplying a synthetic resin material into a molding die into which the input shaft 2 is inserted. Irregularities such as knurls into which the synthetic resin material enters are formed on the outer periphery of the input shaft 2, whereby the second valve member 25 is firmly fixed to the input shaft 2.

When the torsion bar 3 is elastically twisted in accordance with the steering resistance, the two valve members 24 and 25 elastically rotate relative to each other in accordance with the steering resistance.

As shown in FIG. 9, the first valve member 2
A plurality of recesses along the axial direction are formed at equal intervals in the circumferential direction on the inner circumference of the fourth member 4 and the outer circumference of the second valve member 25. The first
The recesses on the valve member side are located at equal intervals in the circumferential direction.
One right steering recess R and three left steering recesses L located at regular intervals in the circumferential direction. The second valve member-side recess has three pressure oil supplies located at regular intervals in the circumferential direction. And three pressure oil discharge recesses T located at equal intervals in the circumferential direction. Each right steering recess R and each left steering recess L are alternately arranged in the circumferential direction, and each pressure oil supply recess P and each pressure oil discharge recess T are alternately arranged in the circumferential direction. Each of the first valve member-side concave portions R and L is formed so as to penetrate the first valve member 24, and each of the second valve member-side concave portions P and T is formed so as to penetrate the second valve member 25.

The axial ends of each of the right steering recess R and the left steering recess L are located between the axial ends of the first valve member 24. The axial ends of each pressure oil supply recess P are: It is located between both ends in the axial direction of the second valve member 25. As shown in FIGS. 10 and 11, (1), (2) and FIG. 12, both ends of each pressure oil discharging recess T in the axial direction are extended through the extended recess 38a penetrating the second valve member 25. It reaches both axial ends of the valve member 25. Thereby, each pressure oil discharge concave portion T and the extended concave portion 3
8a form three grooves that open at both ends in the axial direction, and the grooves divide the second valve member 25 into three. In the illustrated example, the circumferential width of each extension recess 38a is smaller than the circumferential width of the pressure oil discharge recess T, but the invention is not limited to this.

As shown in FIGS. 8 and 9, each right steering recess R is provided with a hydraulic pressure from a flow path 31 formed in the first valve member 24 via a right steering port 32 formed in the valve housing 10a. It communicates with one oil chamber 21 of the cylinder 18. Each left steering recess L communicates from the flow path 33 formed in the first valve member 24 to the other oil chamber 22 of the hydraulic cylinder 18 via a left steering port 34 formed in the valve housing 10a. Each pressure oil supply concave portion P is connected to a flow passage 35 formed in the first valve member 24 through a valve housing 10.
It communicates with a pump 37 through an inlet port 36 formed in a. Each of the recesses T for discharging pressure oil is provided with the extension recess 38a, the first
The upper space 51 of the valve member 24 in FIG.
An outlet port 40 formed in the valve housing 10 a communicating with the upper space 51 forms a pressure oil return flow path, and communicates with the tank 41. The lower space 52 in FIG. 8 of the first valve member 24 communicates with the tank 41 via the upper space 51 and the outlet port 40 from the groove formed by the pressurized oil discharge recess T and the extension recess 38a. This allows
The pump 37, the tank 41, and the respective oil chambers 21 and 22 of the hydraulic cylinder 18 communicate with each other through an inter-valve flow path between the inner and outer circumferences of the first valve member 24 and the second valve member 25. In the inter-valve flow path, an opening between the edge along the axial direction of the first valve member-side recess and the edge along the axial direction of the second valve member-side recess is opened by the relative rotation of the two valve members 24 and 25. The apertures A, B, C, and D change in degree. Each axial edge of the second valve member side concave portions P, T is a chamfer. The chamfer is formed when the second valve member 25 is formed. Each of the apertures A, B, C,
D communicates with the pump 37, the tank 41, and the oil chambers 21 and 22 of the hydraulic cylinder 18, and the throttle portions A, B, C,
The hydraulic pressure acting on the hydraulic cylinder 18 is controlled by the change in the opening degree of D.

FIG. 9 shows the relative positions of the two valve members 24 and 25 in a non-steering state. In this state, each of the pressure oil supply recesses P and each of the pressure oil discharge recesses T have all the throttle portions. Since the fluid flows through A, B, C, and D, the pressure oil supplied from the pump 37 is directly returned to the tank 41 and no steering assist force is generated. When the steering wheel is steered to the right from a state in which the steering assist force is not generated, the torsion bar 3 is twisted in accordance with the steering resistance applied to the wheels from the road surface, and the two valve members 24 and 25 relatively rotate. As a result, the opening degree of the throttle portion A between each right steering recess R and each pressure oil supply recess P and each left steering recess L
The degree of opening of the throttle portion B between the hydraulic fluid discharge recess T and the pressure oil discharge concave portion T increases, and the degree of opening of the throttle portion C between each right steering concave portion R and each hydraulic oil discharge recess T and each left steering. The degree of opening of the throttle portion D between the pressure recess L and each pressure oil supply recess P is reduced. As a result, one oil chamber 21 of the hydraulic cylinder 18 is moved from the pump 37
Pressure oil is supplied to the other oil chamber 22 of the hydraulic cylinder 18.
The pressure oil is returned to the tank 41, and the steering assist force to the right of the vehicle acts on the rack 8 according to the steering resistance. Further, when the steering is performed to the left from a state in which no steering assist force is generated, the opening of each of the throttle portions A, B, C, and D changes in reverse to the case where the steering is performed to the right. The auxiliary force acts on the rack 8 according to the steering resistance.

As shown in FIGS. 11A and 11B, in order to prevent the torsion bar 3 from being damaged by restricting the relative rotation between the input shaft 2 and the output shaft 4 to a certain range, the input shaft 2 2, a first regulating portion 61 similar to that of the first embodiment is formed, and a second regulating portion (not shown) similar to that of the first embodiment is formed in the concave portion 4a formed at one end of the output shaft 4. The relative rotation between the input shaft 2 and the output shaft 4 is restricted to a certain range by the contact between the first restriction part 61 and the second restriction part.

According to the second embodiment, the same operations and effects as those of the first embodiment can be obtained. Furthermore, the second valve member 25 made of synthetic resin is divided by a groove along the axial direction, but is fixed to the input shaft 2 by insert molding. The pressurized oil return flow path can be constituted by the groove along the axial direction without increasing the size for fixing, that is, without increasing the size of the device.

The present invention is not limited to the above embodiment. For example, the present invention may be applied to a ball screw type hydraulic power steering device.

[0041]

According to the present invention, machining accuracy is improved, there is no variation in steering characteristics, assembly is easy, the weight of the device can be reduced, abnormal noise can be prevented, and the yield in the manufacturing process can be improved. In addition, it is possible to provide a hydraulic power steering device that can improve the degree of freedom in electrical and magnetic design and can reduce the number of processing steps of the hydraulic oil return flow path without increasing the size of the device.

[Brief description of the drawings]

FIG. 1 is a sectional view of a hydraulic power steering device according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a first valve member of the hydraulic power steering device according to the first embodiment of the present invention.

FIG. 3 is a sectional view taken along line III-III of FIG. 1;

FIG. 4 is a perspective view of a second valve member and an input shaft of the hydraulic power steering device according to the first embodiment of the present invention.

FIG. 5 is a side view and (2) is an end view of a second valve member and an input shaft of the hydraulic power steering device according to the first embodiment of the present invention.

FIG. 6 is a second valve member and an input shaft (1) of the hydraulic power steering apparatus according to the first embodiment of the present invention.
(2) is a sectional view taken along the line VI (1) -VI (1), and (2) is a sectional view taken along the line VI (2) -VI (2) of FIG.

FIG. 7 is a cross-sectional view of a main part of the hydraulic power steering device according to the first embodiment of the present invention.

FIG. 8 is a sectional view of a hydraulic power steering device according to a second embodiment of the present invention.

9 is a sectional view taken along line IX-IX of FIG.

FIG. 10 is a sectional view taken along line XX of FIG. 9;

FIG. 11 is a side view and (2) is an end view of a second valve member and an input shaft of a hydraulic power steering apparatus according to a second embodiment of the present invention.

12 is a sectional view taken along line XII-XII of FIG.

[Explanation of symbols]

 2 Input shaft 4 Output shaft 18 Hydraulic cylinder 24 First valve member 25 Second valve member 37 Pump 38a Extension recess 41 Tank A, B, C, D Restrictor P, T Second valve member side recess R, L First valve Member side recess

Claims (3)

[Claims] An input shaft; an output shaft elastically connected to the input shaft so as to be relatively rotatable; a cylindrical first valve member connected or integrated with the output shaft so as to be rotatable with the output shaft; A cylindrical second valve member inserted into the first valve member so as to be relatively rotatable and integrated with the outer periphery of the input shaft; and an inner periphery of the first valve member and an outer periphery of the second valve member. A plurality of recesses are formed at intervals in a circumferential direction, and a pressure oil is provided between an edge of the first valve member-side recess along the axial direction and an edge of the second valve member-side recess along the axial direction. A throttle that communicates with the supply pump, the hydraulic actuator for generating steering assist force, and the tank, and whose opening changes according to the relative rotation of the two valve members, changes the opening of the throttle to generate steering assist force. Hydraulic actuator A hydraulic power steering device capable of controlling the hydraulic pressure acting on the hydraulic power steering device, wherein the second valve member is made of synthetic resin. 2. The second valve member is divided into a plurality of grooves by axial grooves that open at both ends in the axial direction, and the grooves form a pressure oil return flow path between the throttle portion and the tank. Item 2. The hydraulic power steering device according to item 1. 3. The second valve member is insert-molded by supplying a synthetic resin material into a molding die into which the input shaft is inserted, and the outer periphery of the input shaft is formed with irregularities into which the synthetic resin material enters. The hydraulic power steering device according to claim 1 or 2, wherein