JPH09277951A - Steering force control device for hydraulic power steering system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering force control device for a hydraulic power steering system for reducing steering force of an automobile in which power assist quantity (steering assist force) can be controlled in accordance with automobile running conditions such as the car speed, steering angle. SOLUTION: In a hydraulic power steering system 1, a hydraulic reaction mechanism 60 provided in a valve housing 20 of a rotary servo valve 2 has a flat part 46 forded on the output side of a stub shaft 22 as an input shaft, two plunger holes 56 opened to face a flat surface 45 of the flat part 46 in the diametric direction of a pinion 23 as an output shaft, and two plungers 64 slidably engaged in the respective plunger holes 56.

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 system for reducing the steering force of an automobile,
The present invention relates to a steering force control device capable of controlling a power assist amount (steering assist force) according to a vehicle traveling state such as a vehicle speed and a steering angle.

[0002]

2. Description of the Related Art Steering reaction force when a vehicle is stopped or running at a low speed is extremely large due to a large frictional force between a tire and a road surface, and a hydraulic power steering device is used to reduce the steering reaction force.

Normally, a hydraulic pump for a hydraulic power steering device is a variable discharge type pump whose discharge flow rate increases and decreases in proportion to the number of revolutions. Increases (the vehicle speed and the pump speed do not necessarily have a proportional relationship due to the change of the gear ratio, but there is a corresponding relationship), the power assist amount increases, and steering with a small steering force becomes possible, which is appropriate. I can't get a good driving feeling.

In order to solve such a problem, a steering force control device disclosed in Japanese Patent Publication No. 7-112825 (see FIG. 1).
6 to FIG. 18).

In the conventional steering force control device shown in FIGS. 16 to 18, a projection portion 02 projecting diametrically on the input shaft 01 is provided.
Is formed, and four cams 03 are formed on the outer circumference of the outer circumference at equal intervals in the circumferential direction.
A shaft portion 04 is provided between the input shaft 01 and the shaft portion 03, and the projection portion 02 of the input shaft 01 is provided.
A notch 06 is formed in the output shaft 05 at a required interval in the circumferential direction, and a plunger hole 07 is formed in the radial direction of the cam 03 of the input shaft 01, and a plunger 08 is formed in the blanker hole 07. Slidingly fitted, the plunger 08 and the cam 03
A ball 09 is inserted in the and
When 01 is rotated, pressure oil is supplied to the outer end side of the plunger hole 07, the plunger 08 is moved toward the center, and the pole 09 is pressed against the cam 03, thereby suppressing the rotation of the input shaft 01. It was supposed to be done.

[0006]

In the steering force control device shown in FIGS. 16 to 18, the projection 02 and the cam 03 are provided.
Since the shaft portion 04 exists between and, it is inevitable that the input shaft 01 becomes long and the entire rotary servo valve becomes large.

Further, a relative rotation restricting mechanism comprising a projection 02 of the input shaft 01 and a notch 06 of the output shaft 05, and the input shaft 01
The cam 03, the plunger hole 07 of the output shaft 05, the plunger 08, and the hydraulic reaction mechanism consisting of the ball 09 are separate bodies, so the structure is complicated, and there are four plungers 08, and the ball 09 is required. Therefore, the number of parts is increased and it is difficult to reduce the cost.

[0008]

SUMMARY OF THE INVENTION The present invention relates to an improvement of a steering force control device for a hydraulic power steering system that overcomes the above problems, and pressure oil discharged from a hydraulic pump passes through a rotary servo valve. Hydraulic power steering device in which oil in the other cylinder chamber of the hydraulic power cylinder is guided to either of the two cylinder chambers of the hydraulic power cylinder via the rotary servo valve to the suction port of the hydraulic pump. In the rotary servo valve, the input shaft, an output shaft arranged on the same axis with respect to the input shaft, a torsion bar connecting the input shaft and the output shaft so as to be relatively twistable, and the input shaft An input shaft sleeve fitted relatively rotatably to the outer circumference of the shaft, and a valve housing for sealing the input shaft and the input shaft sleeve. The output shaft and the input shaft sleeve are relatively non-rotatably coupled to each other, and a hydraulic reaction mechanism provided in the valve housing of the rotary servo valve is provided on the output side of the input shaft. A flat portion formed by cutting out along a plane parallel to the center line of the input shaft, and the output shaft, which is opened to face the flat surface of the input shaft flat portion along the diametrical direction of the output shaft. Two plunger holes and two plungers slidably fitted in the plunger holes of the output shaft, and the output shaft has a space with respect to the flat portion of the input shaft. Then, a deformed hole that allows a certain degree of relative rotation between the input shaft and the output shaft is formed on the input side of the plunger hole,
The hydraulic fluid is introduced into the hydraulic chamber on the outer diameter side of the plunger in the plunger hole through a hydraulic control valve that opens and closes in accordance with a vehicle traveling state such as vehicle speed and steering angle.

Since the present invention is configured as described above, when it is necessary to reduce the amount of power assist under vehicle traveling conditions such as vehicle speed and steering angle, the output shaft of the output shaft is changed according to the vehicle traveling state. As a result of the pressure oil being introduced into the hydraulic chamber on the outer diameter side of the plunger in the plunger hole, a reaction force opposite to the steering direction of the input shaft is applied to the input shaft by the plunger protruding with the pressure oil. The amount of power assist is reduced, and a steering feeling adapted to the driving state of the vehicle can be obtained.

Further, according to the present invention, since the two plunger holes are opened to the flat surface of the flat portion of the input shaft along the diametrical direction of the output shaft, the diameter of the plunger hole and the diameter of the plunger are increased. When the outer peripheral portion of the plunger comes into contact with the flat surface by the rotation of the input shaft, a line parallel to the center line of the plunger hole passing through the contact portion and a center line of the input shaft can be provided. As a result, even if the pressure oil pressure introduced into the hydraulic chamber is not so large, a large steering reaction force can be obtained and the rotary servo valve can be downsized.

Further, according to the present invention, since two plungers are sufficient and a cam follower such as a ball is not required, the number of parts can be reduced and the cost can be reduced.

According to the present invention as set forth in claim 2, there is no need to provide two pressure oil introduction ports in the valve housing, or the pressure oil introduction groove in the circumferential direction is formed on the inner peripheral surface of the valve housing. Even if the pressure oil is not provided, the pressure oil can be evenly introduced into the hydraulic chambers in the two plunger holes.

According to the third aspect of the present invention, the plunger fitted in the plunger hole can be prevented from falling off, and the elastic restoring force of the ring-shaped elastic body can cause the plunger to move. The flat surface of the input shaft can be pressed with a required force.

Furthermore, by constructing the present invention as set forth in claim 4, the hydraulic control valve can be simply constructed and the cost can be reduced.

Further, by constructing the present invention as set forth in claim 5, the reaction force of the pressure oil introduced into the hydraulic chamber is continuously changed according to the traveling state of the vehicle such as the vehicle speed and the steering angle. Therefore, it is possible to obtain an appropriate steering feeling suitable for the traveling state of the automobile.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention shown in FIGS. 1 to 14 will be described below. In the hydraulic power steering apparatus 1, as shown in FIG. 1, a rotary servo valve body unit 2 and a hydraulic power cylinder 3 are integrally assembled, and a tie rod 4 is attached to a piston rod 9 of the hydraulic power cylinder 3. The front wheel 5 is connected through the hydraulic power cylinder 3 with the piston 10 as shown in FIG.
It is partitioned into an 11 and a right cylinder chamber 12 (in FIG. 2, the vehicle is seen from the front to the rear, which is left-right reversed).

A steering column shaft 7 integrated with the steering wheel 6 is connected to a stub shaft 22 which is an input shaft of the rotary servo valve body unit 2 through a steering joint 8 so that the steering wheel 6 is rotated clockwise or counterclockwise. When the stub shaft 22 is rotationally driven in the direction, the stub shaft 22 is rotationally driven in response to the stub shaft 22, and the pressure oil is transferred to the right cylinder chamber 12 or the left cylinder chamber 11 of the hydraulic power cylinder 3 in response to the rotation of the stub shaft 22. Is supplied to drive the piston rod 9 to the left or to the right, and the front wheel 5 can be turned to the right or to the left.

Further, as shown in FIG. 2, in the rotary servo valve body unit 2, the valve housing 20 and the gear housing 21 are integrally connected to each other, and the valve housing 20 is provided in the valve housing 20.
An input shaft stub shaft 22 rotatably fitted to the input end side of the shaft via a bush 26, a torsion bar 24 connecting the stub shaft 22 and the output shaft pinion 23 in a relatively twistable manner, and a valve An stub shaft sleeve 25, which is an input shaft sleeve concentrically and rotatably fitted between the housing 20 and the stub shaft 22, and a hydraulic reaction mechanism 50 interposed between the stub shaft sleeve 25 and the pinion 23 are provided. The pinion 23 is rotatably fitted to the gear housing 21 via a bearing 27,
The pinion 23 meshes with a rack 13 that is integral with the piston rod 9, and the pinion 23 is rotationally driven by the rack 13 that moves integrally with the left and right sliding of the piston 10.

Further, the valve housing 20 is connected to a discharge port 15 of the hydraulic pump 14 and an intake port 16 of the hydraulic pump 14 or a reserve tank 17, which are in communication with each other.
28 and an oil discharge port 29 are formed, and a left cylinder port 11 and a right cylinder port 31 that communicate with the left cylinder chamber 11 and the right cylinder chamber 12 of the hydraulic power cylinder 3 are formed.

Moreover, a circumferential oil supply groove 32 communicating with the oil supply port 28 is formed on the outer peripheral surface of the stub shaft sleeve 25, and a circumferential left oil passage communicating with the left cylinder port 30 and the right cylinder port 31 is formed. Cylinder groove 33
Also, the circumferential right cylinder groove 34 is formed on both axial sides of the circumferential oil supply groove 32.

Further, as shown in FIG. 3, the stub shaft sleeve 25 is provided with four oil supply passages 35 which are directed to the central axis thereof and whose outer ends are opened to the oil supply groove 32 in the circumferential direction. Left cylinder passages 36 and right cylinder passages 37, which are formed at intervals and are oriented toward the center line of the stub shaft sleeve 25, are formed on both sides in the circumferential direction of the oil supply passage 35. The outer end of the right cylinder passage 37 is open to the circumferential left cylinder groove 33 and the circumferential right cylinder groove 34, respectively.

Furthermore, on the inner peripheral surface of the stub shaft sleeve 25, the center of the left cylinder passage 36 and the center of the right cylinder passage 37 coincide with the groove center, and an axial groove 38 parallel to the axial direction of the stub shaft sleeve 25 is formed. And four axial grooves 39 are alternately formed, and the inner ends of the left cylinder passage 36 and the right cylinder passage 37 are open to the axial grooves 38 and 39, respectively.

Furthermore, on the outer peripheral surface of the stub shaft 22, the axial groove 38 and the axial groove of the stub shaft sleeve 25 are formed.
Axial grooves 40 and axial grooves 41 having a width equal to the width of the portion sandwiched by 39 are formed alternately at equal intervals in the circumferential direction, and communicate the central hole 44 of the stub shaft 22 with the axial groove 41. An oil drain passage 42 is formed, and the center hole 44 communicates with the oil drain port 29 via another oil drain passage 43.

In addition, the output portion of the stub shaft 22 has a flat portion 46 cut away along a flat surface 45 parallel to the center line of the stub shaft 22, and a cylinder 47 on the output side thereof.
A communication hole 48 that connects the center hole 44 of the stub shaft 22 and the outside of the flat surface 45 is formed.

A circular hole 50 into which the stub shaft sleeve 25 can be fitted and a flat portion 46 of the stub shaft 22 are loosely fitted in the center of the pinion 23 from the input end of the pinion 23 toward the output side. A deformable hole 51, a circular hole 52 into which the cylinder 47 of the stub shaft 22 can be fitted via a sleeve 61, and a spline hole 53 into which a spline 62 of the torsion bar 24 can be fitted are sequentially formed. The stub shaft 22 and the pinion 23 can be rotated relative to each other by twisting, but the relative rotation angle does not exceed a predetermined angle due to the engagement between the flat portion 46 of the stub shaft 22 and the deformed hole 51. Is being regulated. Further, on the outer peripheral portion of the pinion 23, a cylindrical portion 54 that can be fitted into the output side notch recess 49 of the stub shaft sleeve 25 is provided from the input end of the pinion 23 toward the output side. And a large diameter portion 55 is formed on the outer peripheral side of the deformed hole 51, and the large diameter portion 55 has a deformed hole 51 that opens to a wide portion of the deformed hole 51 and a periphery of an outer end thereof. A directional communication groove 57 is formed.

Further, an engagement notch 58 is formed in the tubular portion 54 of the pinion 23, and a pin 63 is driven into a notch recess 49 on the output side of the stub shaft sleeve 25, and the pin 63 is attached to the pin 63. The engaging notch 58 is engaged.

However, the steering electronic control unit 70 is
The output side flat portion 46 of the stub shaft 22 and the large diameter portion 55 of the pinion 23 make the flat surface 45 of the flat portion 46 of the stub shaft 22.
Two plunger holes 56 that are opened with respect to each other, and a plunger 64 that is slidably fitted in each of the plunger holes 56.
The plunger 64 includes two plunger holes 56 opened to the flat surface 45 of the flat portion 46, and a ring-shaped rubber band 65 slidably fitted in each of the plunger holes 56.
The ring-shaped rubber band 65 is held by the ring-shaped rubber band 65 fitted in the circumferential communication groove 57 so as not to fall out of the plunger hole 56. A seal 66 is fitted in the seal groove 59 of the pinion 23.

A steering electronic control unit 70 is attached to the valve housing 20, and the steering electronic control unit 70 receives a vehicle speed signal from a vehicle speed detecting means (not shown). When the valve body 73 of the hydraulic control valve 72 is pushed downward by overcoming the spring force of the compression coil spring 75 and the speed becomes slower than during parking, the current of the linear solenoid 71 changes from large to small and the hydraulic control valve 72 The valve body 73 is pushed upward by the spring force of the compression coil spring 75.

Further, the valve body 73 of the hydraulic control valve 72 is a land
The land 74 includes a pressure oil passage 76 connected to the oil supply port 28 of the valve housing 20 and a pressure oil passage 67 connected to the hydraulic chamber 67 in the plunger hole 56 communicating with the circumferential communication groove 57 of the hydraulic reaction mechanism 60. The oil passage 77 is blocked or communicated.

Furthermore, a return passage 78 is formed in the valve body 73, the return passage 78 is communicated with the drain oil passage 43 through the return passage 79, and the pressure oil passage 77 is cut off from the pressure oil passage 76. When the oil is spilled, the pressure oil in the hydraulic chamber 67 of the plunger hole 56 passes through the oil drain passage 43 and the oil drain port 29, and the reserve tank 17
Is to be discharged.

Since the embodiment shown in FIGS. 1 to 14 is constructed as described above, the embodiment shown in FIGS. 1 to 17 is constructed as described above. Of the rotary servo valve body unit 2 when the steering force of the rotary servo valve body unit 2 is not moving, the stub shaft 22 is in the neutral position, the external force does not act on the front wheel 5, and the vehicle is facing straight. Is set to the state shown in FIG. 16 and is discharged from the hydraulic pump 14 to supply the oil.
The pressure oil supplied to the inside 28 is supplied from the circumferential oil supply groove 32 to the oil supply passage.
The oil flows through the axial groove 40 into the axial groove 40, is evenly divided into left and right, and is exhausted through the axial groove 38, the axial groove 39, the axial groove 41, the oil drain passage 42, and the oil drain passage 43. Flowing to 29, returning to the suction port of the hydraulic pump 14 or the reserve tank 17, the pressure oil is not supplied to either the left cylinder chamber 11 or the right cylinder chamber 12, and the front wheel 5 maintains the straight traveling state.

When the steering wheel 6 is rotated clockwise to turn right, as shown in FIG. 17, in the rotary servo valve body unit 2, only the stub shaft 22 is rotated clockwise. Since the communicating portion between the axial groove 40 and the axial groove 39 is wider than the communicating portion between the axial groove 40 and the axial groove 38, the pressure oil that has passed through the oil supply passage 35 is It flows into the right cylinder chamber 12 through the cylinder passage 37, the circumferential right cylinder groove 34 and the right cylinder port 31, and the piston 10 and the piston rod 9 move to the left (right in FIG. 2). , The front wheel 5 turns to the right, and the vehicle turns right. A description of the state of flowing into the suction port of the hydraulic pump 14 in the left cylinder chamber 11 or the reserve tank 17 is omitted.

When parked, the current of the linear solenoid 71 is large, the spring force of the compression coil spring 75 is overcome, the valve body 73 of the hydraulic control valve 72 is lowered, and the pressure oil passage 76 is reached.
The pressure oil is not introduced into the hydraulic chamber 67 in the plunger hole 56 communicating with the circumferential communication groove 57 because the pressure oil passage 77 is cut off, and the plunger 64 is pushed by the pressure oil pressure in the hydraulic chamber 67. When the stub shaft 22 is rotated by the torque applied to the steering wheel 6 so that it cannot be strongly pressed against the flat surface 45 of the flat portion 46 of the
The flat part 46 integrated with 22 does not receive a large resistance force, and the pinion
The stub shaft can be rotated in 23 irregular holes 51.
The steering reaction force by the hydraulic reaction force mechanism 60 is not applied to 22.

However, when shifting from the parking state to the low speed range, the current of the linear solenoid 71 decreases and the hydraulic control valve 72
The valve main body 73 rises due to the spring force of the compression coil spring, the pressure oil passage 76 and the pressure oil passage 77 are communicated with each other, and the pressure oil discharged from the discharge port 15 of the hydraulic pump 14 is supplied to the oil supply port 28 and the circumferential direction. Since the plunger 64 is introduced into the hydraulic chamber 67 through the oil supply groove 32, the pressure oil passage 76 and the pressure oil passage 77 and the plunger 64 is strongly pressed against the flat portion 46 of the stub shaft 22, steering force is applied to the steering wheel 6 in this state. Stub shaft
When the torque is transmitted to 22, the front wheel 5 is connected to the piston rod 9 of the hydraulic power cylinder 3 and the rack 13
The pinion 23 connected to the stub shaft 22
Not only receives the torsional rigidity of the torsion bar 24, but also the flat portion 46 is pinched by the plunger 64 of the hydraulic reaction mechanism 60, and receives the rotation restraining force of the flat portion 46. As a result, the power assist amount is reduced. Will be reduced.

Further, in the embodiment shown in FIGS. 1 to 14, the plunger 64 of the hydraulic reaction mechanism 60 has the stub shaft 22.
Since the flat portion 46 is directly contacted with the plunger 64 and the number of the plungers 64 is two, the number of parts can be reduced, and the size and weight can be reduced and the cost can be reduced.

Further, after the plunger 64 is fitted in the plunger hole 56 of the pinion 23, the circumferential communication groove 57 of the pinion 23 is inserted.
Since the ring-shaped rubber band 65 is fitted on the
Since 64 does not fall out of the plunger hole 56, the assembly becomes easy.

The end surface of the land 74 of the valve body 73 of the hydraulic control valve 72 in the embodiment shown in FIGS. 1 to 14 is a plane perpendicular to the center line thereof, but as shown in FIG. The end surface of the land 74 is inclined to form a conical surface,
If the valve body 73 is moved in the axial direction according to the vehicle speed of the automobile, the power assist amount can be continuously reduced.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a front half of an automobile equipped with a steering force control device for a hydraulic power steering device according to the present invention.

FIG. 2 is a vertical sectional front view showing an embodiment of a steering force control device for a hydraulic power steering device of the present invention.

FIG. 3 is a cross-sectional view taken along the line III-III of FIG.

FIG. 4 is an enlarged vertical sectional front view of an essential part of FIG.

FIG. 5 is an exploded perspective view of a hydraulic reaction force mechanism.

FIG. 6 is a vertical sectional view of a stub shaft.

7 is a transverse cross-sectional view cut along the line VII-VII of FIG.

8 is a transverse cross-sectional view cut along the line VIII-VIII in FIG.

FIG. 9 is a front view of the pinion.

10 is a cross-sectional view taken along the line XX in FIG.

11 is a view as viewed in the direction of the arrow XI in FIG. 9;

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

FIG. 13 is a transverse cross-sectional view of a main part illustrating an angular relationship between a stub shaft and a stub shaft sleeve and a pressure oil flow state in a neutral state.

FIG. 14 is a transverse cross-sectional view of a main portion illustrating an angular relationship between a stub shaft and a stub shaft sleeve and a pressure oil flow state when a steering wheel is rotated clockwise to set a right steering state.

FIG. 15 is a longitudinal sectional view of an essential part of a hydraulic control valve according to another embodiment of the present invention.

FIG. 16 is a longitudinal sectional view of a main part of a conventional hydraulic power steering device.

FIG. 17 is a cross-sectional view taken along the line XVII-XVII of FIG.

FIG. 18 is a cross-sectional view taken along the line XVIII-XVIII of FIG.

[Explanation of symbols]

1 ... Hydraulic power steering device, 2 ... Rotary servo valve, 3 ... Hydraulic power cylinder, 4 ... Tie rod, 5 ... Front wheel, 6 ... Steering wheel, 7 ... Steering column shaft, 8 ... Steering joint, 9 ... Piston rod, 10 ... Piston, 11 ... Left cylinder chamber, 12 ... Right cylinder chamber, 13 ... Rack, 14 ... Hydraulic pump, 15 ... Discharge port, 16 ... Suction port, 17 ... Reserve tank, 20 ... Valve housing, 21 ... Gear housing, twenty two…
Stub shaft, 23 ... pinion, 24 ... torsion bar,
25 ... Stub shaft sleeve, 26 ... Bushing, 27 ... Bearing, 28 ... Oil supply port, 29 ... Oil discharge port, 30 ... Left cylinder port, 31 ... Right cylinder port, 32 ... Circumferential lubrication groove, 33 ... Circumferential direction Left cylinder groove, 34 ... Circumferential right cylinder groove, 35 ... Oil supply passage, 36 ... Left cylinder passage, 37 ... Right cylinder passage, 38 ... Axial groove, 39 ... Axial groove, 40 ... Axial groove , 41 ... axial groove, 42 ... drain passage, 43 ... drain passage,
44 ... central hole, 45 ... flat surface, 46 ... flat portion, 47 ... cylinder, 48 ...
Communication hole, 49 ... Notched recess, 50 ... Circular hole, 51 ... Deformed hole, 52 ...
Circular hole, 53 ... Spline hole, 54 ... Cylindrical part, 55 ... Large diameter part, 56
… Plunger hole, 57… Circumferential communication groove, 58… Engagement notch,
59 ... Seal groove, 60 ... Hydraulic reaction mechanism, 61 ... Sleeve, 62 ...
Spline, 63 ... Pin, 64 ... Plunger, 65 ... Ring rubber band, 66 ... Seal, 67 ... Hydraulic chamber, 70 ... Steering electronic control unit, 71 ... Linear solenoid, 72 ... Hydraulic control valve,
73 ... Valve body, 74 ... Land, 75 ... Compression coil spring,
76 ... Pressure oil passage, 77 ... Pressure oil passage, 78, 79 ... Return passage.

Claims (5)

[Claims] 1. The pressure oil discharged from a hydraulic pump is guided to either one of both cylinder chambers of a hydraulic power cylinder via a rotary servo valve, and the oil in the other cylinder chamber of the hydraulic power cylinder is transferred to the rotary cylinder. In the hydraulic power steering device guided to the intake port of the hydraulic pump via a servo valve, the rotary servo valve includes an input shaft, an output shaft arranged on the same axis as the input shaft, and the input shaft. A torsion bar that relatively twistably connects the shaft and the output shaft, an input shaft sleeve that is relatively rotatably fitted to the outer periphery of the input shaft, and a valve that seals the input shaft and the input shaft sleeve. A housing, the output shaft and the input shaft sleeve are relatively non-rotatably coupled to each other, and a valve housing of the rotary servo valve. The hydraulic reaction force mechanism provided in the output shaft of the input shaft, the flat portion formed by cutting along a plane parallel to the center line of the input shaft, the output shaft to the output Two plunger holes opened along the diameter direction of the shaft so as to face the flat surface of the flat portion of the input shaft, and two plunger holes slidably fitted in the plunger holes of the output shaft, respectively. The output shaft has a deformed hole that is spaced from the flat portion of the input shaft and allows a certain degree of relative rotation between the input shaft and the output shaft. The hydraulic oil is introduced into the hydraulic chamber on the outer diameter side of the plunger in the plunger hole, the hydraulic oil being introduced through a hydraulic control valve that opens and closes according to the vehicle running state such as vehicle speed and steering angle. Steering force control device for hydraulic power steering system. 2. The steering force of the hydraulic power steering device according to claim 1, wherein a circumferential communication groove is formed in the output shaft on the outer peripheral side of the plunger hole in the circumferential direction. Control device. 3. The steering force control device for a hydraulic power steering system according to claim 2, wherein a ring-shaped elastic body is fitted in the circumferential communication groove of the output shaft. 4. The hydraulic control valve is configured to continuously change a pressure of hydraulic pressure introduced into the hydraulic chamber according to a vehicle traveling state such as a vehicle speed and a steering angle. A steering force control device for a hydraulic power steering device according to any one of claims 1 to 3. 5. The hydraulic control valve is a solenoid on / off device.
The steering force control device for a hydraulic power steering device according to claim 1, wherein the steering force control device is opened and closed by an off operation.