JP2504303Y2 - Power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a hydraulic power steering apparatus in which a source of steering assist force is a hydraulic actuator.
The present invention relates to a power steering apparatus including a hydraulic reaction force device that restrains a control operation of a hydraulic control valve that controls a hydraulic pressure supplied to the hydraulic actuator.

[Prior art]

A hydraulic power steering apparatus using a hydraulic actuator such as a hydraulic cylinder arranged in a steering mechanism as a source of a steering assist force is, for example, operatively connected to an input shaft connected to a steering wheel and a steering wheel. The output shaft and the output shaft are coaxially connected to each other, and when steering torque is applied to the steered wheels, a relative angular displacement is generated between the two shafts according to the torsion of the torsion bar accompanying the steering torque. , A cylindrical casing that rotates in conjunction with one of both shafts, and is coaxially fitted inside this casing,
A hydraulic control valve having a valve body that rotates in conjunction with the other is configured in the connecting portion, and the hydraulic pressure supplied to the hydraulic actuator is controlled by the operation of the hydraulic control valve according to the direction and magnitude of the steering torque. It is configured to obtain a steering assist force by being controlled.

By the way, the magnitude of the force required to operate the steering wheel for steering corresponds to the magnitude of the reaction force that acts on the steered wheels from the road surface.
It is generally known that the magnitude of this reaction force corresponds to a slow vehicle speed. On the other hand, in the power steering apparatus having the above-described configuration, the correspondence relationship between the steering torque applied to the steered wheels and the steering assist force generated by the hydraulic actuator is determined only by the torsion characteristics of the torsion bar.

Therefore, when this torsion bar is selected with a large reaction force at the time of stop or low speed running as a reference, steering is performed with a slight force applied to the steered wheels during high speed running, which causes deterioration of straight running stability. On the contrary, when the torsion bar is selected on the basis of high speed traveling, there is a problem that sufficient steering assist force cannot be obtained during stop and low speed traveling.

In order to solve this difficulty, a hydraulic control valve is installed in parallel at the connecting portion between the input shaft and the output shaft, and a hydraulic reaction force that increases or decreases in response to the vehicle speed is applied between both shafts so that the two shafts can move relative to each other. A power steering apparatus has been developed which includes a hydraulic reaction force portion that restrains the control operation of the hydraulic control valve that occurs according to angular displacement with a strong force at high speed and with a weak force at low speed.

FIG. 5 is an enlarged transverse sectional view of an essential part showing an example of a conventional hydraulic reaction force part. The hydraulic reaction force portion is formed within a cylindrical housing 10 that supports both the input shaft and the output shaft at a connecting portion between the shafts. Reference numeral 30 in the figure denotes, for example, a cylindrical portion that is coaxially connected to the connecting end portion of the output shaft and is rotatably fitted into the housing 10 so that the cylindrical portion is provided between the inner peripheral surface of the housing 10. The reaction chamber as an annular space with an appropriate width in the axial direction.
33 are formed. A part of the input shaft 2 is loosely fitted inside the cylindrical portion 30, and a plurality of recesses 22, 22 ... Equally arranged in the circumferential direction are formed on the outer peripheral surface of the loosely fitted portion. is there. Further, in the cylindrical portion 30, through holes 31, 31, ... penetrating in the radial direction are formed at positions corresponding to the respective recesses 22, 22 ,. Each of them has a separate plunger 32, 32 ... Slidably fitted therein. Each of the plungers 32, 32 ... Has a hemispherical convex portion at the inner end thereof, and the convex portion is engaged with the concave portions 22, 22 formed on the outer periphery of the input shaft 2 as shown in the drawing.

Reference numeral 4 in the drawing denotes a torsion bar that connects the input shaft 2 and the output shaft, and when a steering torque is applied to the steering wheel, the input shaft 2 connected to this and the reaction force from the road surface applied to the steered wheels A relative angular displacement occurs due to the torsion of the torsion bar 4 with the output shaft whose rotation is restricted. The hydraulic pressure supplied to the hydraulic actuator for steering assist is controlled according to the relative angular displacement by the operation of a hydraulic control valve (not shown) that is arranged in parallel with the hydraulic reaction portion and that is formed at the connecting portion of both shafts. This is as described above.

On the other hand, the plungers 32, 32 ... Of the hydraulic reaction force portion are pressed inward in the radial direction by the hydraulic pressure inside the reaction force chamber 33 that acts on the outer end surface of the plunger 32, 32.
It is engaged with 2,22 .... As a result, the relative angular displacement between the input shaft 2 and the cylindrical portion 30 forming a part of the output shaft is restricted by the force corresponding to the hydraulic pressure, and the reaction force on the output shaft side corresponds to this hydraulic pressure. As if they were working,
The relative angular displacement does not occur until the steering torque applied to the input shaft 2 via the steering wheel reaches a size that pushes the plungers 32, 32 ... outward in the radial direction against the hydraulic pressure.
Since the hydraulic control system is not operated, the hydraulic actuator does not generate the steering assist force. Therefore, by introducing high and low hydraulic pressures into the reaction force chamber 33 depending on the speed of the vehicle, the rigidity of the steered wheels is imparted during high-speed traveling, and the straight running stability is improved, At the same time, it is possible to obtain a sufficient steering assist force at the time of stop and low-speed traveling to reduce the force required for steering wheel operation as much as possible.

Various means have been proposed as means for making the hydraulic pressure introduced into the reaction force chamber 33 correspond to the vehicle speed. In the power steering apparatus disclosed in Japanese Patent Laid-Open No. 61-200063, a predetermined hydraulic pressure is generated. An oil passage is provided on the discharge side of the hydraulic pump that connects to the hydraulic tank via a variable throttle and a fixed throttle, and the oil pressure between the two throttles in the middle of the oil passage is used as the introduction hydraulic pressure to the reaction chamber 33. The throttle opening is changed according to the detection result of the vehicle speed sensor to obtain the introduced hydraulic pressure corresponding to the vehicle speed, and in Japanese Patent Publication No. 53-45571 and Japanese Utility Model Publication No. 60-38219 disclosed by the present applicant. Is the reaction chamber that is generated by a hydraulic pump (gear pump in the former case, trochoid pump in the latter case) that is mounted on the output shaft of the transmission and driven at a speed corresponding to the vehicle speed. Direct to It is shown those. Further, a throttle oil passage opened and closed according to the movement of the plunger is provided between the reaction force chamber and the low pressure source, whereby a predetermined amount of introduced oil is supplied to the throttle oil passage until the steering torque reaches a predetermined value. It has been proposed that the steering assist force is gradually increased by escaping the steering assist force (Japanese Patent Application No. 63-2881).
No. 43).

[Problems to be solved by the device]

However, in the power steering apparatus that uses the generated hydraulic pressure of the hydraulic pump that generates the hydraulic pressure corresponding to the vehicle speed as described above (hereinafter referred to as the vehicle speed sensor pump) as the introduced hydraulic pressure, the introduced hydraulic pressure is low during low-speed traveling, Reaction chamber
Since the force for pressing the plungers 32, 32 ... Inward in the radial direction at 33 is weak, the plungers 32, 32 ... May move outward in the radial direction due to disturbance such as vibration of the vehicle body. Further, in the power steering apparatus having the hydraulic reaction force portion in which the pressure oil is introduced into the space between the cylindrical portion 30 and the input shaft 2,
When steering is performed at low speed, the pressure of the pressure oil in the hydraulic control valve rises, and the pressure in the space between the cylindrical portion 30 and the input shaft 2 becomes higher than the pressure in the reaction chamber 33. The plungers 32, 32 ... May move radially outward due to the difference. When the plungers 32, 32 ... Have moved radially outward as described above, the plungers 32, 32
There is a gap between the inner end of the input shaft 2 and the recesses 22, 22 on the outer periphery of the input shaft 2, and when steering is performed in this state, the recesses 22, 22 on the outer periphery of the input shaft 2 and the plunger 32, There was a problem that the inner edge of 32 ... collides and a tapping sound is produced at the time of this collision.

The present invention has been made in view of such a situation, and the pressure of the return hydraulic pressure of the hydraulic control valve is applied to the hydraulic reaction force chamber during low speed traveling so that the plunger does not separate from the input shaft. It is an object of the present invention to provide a power steering device that suppresses a tapping sound during steering of a reaction force chamber during low-speed traveling and provides a comfortable steering feeling.

[Means for solving the problem]

A power steering apparatus according to the present invention comprises a valve body formed or connected to an input shaft and a casing formed or connected to an output shaft in response to a steering wheel operation of hydraulic pressure supplied to an actuator that generates a steering assist force. And a plunger mounted movably on a part of the casing or the output shaft, and a reaction force chamber formed on one side of the plunger. Then, a restraining force corresponding to the introduced hydraulic pressure into the reaction force chamber is applied between the valve body and the casing or the output shaft through the plunger, and a hydraulic reaction force portion that restrains the relative motion is provided, In a power steering device that feeds return oil from an actuator to a low pressure source through a return chamber of the hydraulic control valve, a communication oil passage that connects the outlet side of the return chamber and the reaction chamber, and the communication oil passage. Is installed in the Is lower than the pressure in the reflux chamber, characterized by comprising a check valve for flow through the pressure oil in the reflux chamber of the hydraulic control valve to the reaction chamber.

[Action]

In the present invention, when the pressure of the reaction force chamber is lower than the pressure of the return chamber of the hydraulic control valve, the pressure oil flowing out from the return chamber is checked by the communication oil passage that connects the return chamber and the reaction chamber. Although it is made to flow through the valve to the reaction force chamber, in this case, the pressure in the reaction force chamber is increased by the flow of the pressure oil, and the constraint force of the plunger to the valve body or the casing is increased.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings showing an embodiment thereof. FIG. 1 is a longitudinal sectional view showing a main part of the power steering apparatus according to the present invention.

In the figure, 2 is a hollow input shaft, and 3 is an output shaft. These are supported in a common cylindrical housing 10 so as to be rotatable about their respective axes, and are coaxially connected via a torsion bar 4 inserted in the hollow portion of the input shaft 2. . One end of the input shaft 2 that protrudes to the outside of the housing 10 by an appropriate length is connected to a steering wheel (not shown), and steering torque applied to the steering wheel is transmitted to the steering wheel. The output shaft 3 is operatively connected to a steering wheel (not shown) so that the output shaft 3 can be steered according to the amount of rotation of the output shaft 3. This connection is, for example, a rack. In a vehicle equipped with a pinion type steering mechanism, the pinion 3a formed on the outer periphery of the output shaft 3 as shown in the drawing is realized by meshing with the rack shaft 5 in the steering mechanism, and the rotation of the output shaft 3 is realized. Is a pinion
It is converted into a motion of the rack shaft 5 in the axial direction via 3a, and steering is performed in response to this. Further, in the middle of the rack shaft 5, there is a cylinder surrounding the disc-shaped piston 5a coaxially fixed to the rack shaft 5 and the rack shafts 5 on both sides of the piston 5a which are liquid-tightly sealed over a predetermined length. A hydraulic cylinder S for assisting steering, which is a hydraulic actuator, is configured with the cylindrical housing 5b, and the rack shaft 5 can be moved, that is, steered, in accordance with the difference in the hydraulic pressure supplied to both oil chambers of the hydraulic cylinder S. The required force is assisted.

The output shaft 3 is provided with a cylindrical portion 30 coaxially connected to the end portion on the side of connection with the input shaft 2, and the end portion of the input shaft 2 on the side of connection has an appropriate length inside the cylindrical portion 30. It is fitted loosely. The hydraulic control valve 6 for controlling the hydraulic pressure supplied to the hydraulic cylinder S is
It comprises a short cylindrical casing 60 rotatably fitted in the housing 10 and a valve body 61 formed in a part of the input shaft 2 fitted therein.

The casing 60 has a predetermined width on its inner peripheral surface, is equidistantly arranged in the circumferential direction, and is provided with a plurality of long grooves 62, 62 ... Which extend in the axial direction, and one end thereof is driven into the cylindrical portion 30. A part of the rotation stopping pin 30a is engaged with the rotation stopping pin 30a so that the rotation preventing pin 30a rotates with the rotation of the output shaft 3. On the outer peripheral surface of the valve body 61, long grooves 63, 63 ... Having the same number and a predetermined width are provided at positions corresponding to the respective long grooves 62, 62 ... It is arranged. Casing 60
The valves 61 and the respective long grooves 62, 63 are arranged in a staggered manner, and are positioned so as to communicate with the adjacent ones on both sides in the circumferential direction at a predetermined interval, and the long grooves 62, 62 on the casing 60 side.
... are separate pressure guide ports 11 and 12 that penetrate the housing 10 in and out.
And the two oil chambers of the hydraulic cylinder S are alternately communicated with each other. On the other hand, the long grooves 63, 63 on the side of the valve body 61 are connected to the hydraulic pump P, which is a hydraulic pressure generation source, through the introduction ports 13 of which half of which are located at every other position penetrate the housing 10 inside and outside. Further, the other half is communicated with the reflux chamber 64 formed on one side of the casing 60 through the hollow portion of the input shaft 2, and is maintained at a low pressure state via the reflux port 14 penetrating the housing 10 in and out. It is connected to the oil tank T.

The operation of the hydraulic control valve 6 having the above configuration will be briefly described. When a steering torque is applied to the steering wheel, the input shaft 2 connected to the steering wheel tries to rotate in response to the rotation of the steering wheel, while the output connected to the steering wheel via the rack shaft 5 and the pinion 3a. Since the rotation of the shaft 3 is restricted by the road surface reaction force acting on the steered wheels, the torsion bar 4 connecting both shafts is twisted according to the steering torque, and a part of the input shaft 2 is generated. A relative angular displacement occurs between the valve body 61 formed on the shaft and the casing 60 whose rotation is restricted by the output shaft 3. As a result, the area of the gap on both sides of the long groove 63 of the valve body 61 increases as one increases and decreases as the other decreases. As a result, the hydraulic pump P introduces the long groove 63, 63, ... The pressure oil is passed through the gap on the side where the area is increased,
Each of the casings 60 adjacent to each other on the same side flows into the long grooves 62, 62 ... And passes through the pressure introducing port 11 or 12 communicating with them.
The oil is supplied to one oil chamber of the hydraulic cylinder S. The oil in the other oil chamber of the hydraulic cylinder S is the pressure guide port 12 or
The long grooves 62, 62 of the casing 60 communicating with the casing 11 via 11.
Further, it is introduced into the other set of long grooves 63, 63 ... Adjacent to each other on the same side, and is returned to the oil tank through the reflux chamber 64 and the reflux port 14. This causes a pressure difference between both oil chambers of the hydraulic cylinder S, and a steering assist force corresponding to the pressure difference is applied to the rack shaft 5. At this time, the magnitude of the steering assist force generated by the hydraulic cylinder S depends on the change mode of the throttle area generated in the gap between the long grooves 62 and 63 according to the relative angular displacement, and this change mode is the twist of the torsion bar 4. It corresponds unequivocally to the aspect. Therefore, the correspondence relationship between the steering torque applied to the steering wheel and the steering assist force generated by the hydraulic cylinder S by the operation of the hydraulic control valve 6 corresponding thereto is determined only by the torsional characteristics of the torsion bar 4, and as described above, the high speed operation is performed. Poor straight running stability during traveling or insufficient steering assist force during low speed traveling may occur.

The hydraulic reaction force portion 1 that solves such a difficulty by applying a force corresponding to the vehicle speed between the input shaft 2 and the output shaft 3 to restrain the relative angular displacement is a connection side end portion of the output shaft 3. It is configured in the cylindrical portion 30 which is continuously provided. FIG. 2 is an enlarged view of an essential part of FIG. 1 showing the structure of the hydraulic reaction force section 1.
FIG. 3 is a cross-sectional view taken along the line III-III in FIG.

The cylindrical portion 30 has a plurality of through holes that pass through it in the radial direction.
31 and 31 are formed so as to be evenly arranged in the circumferential direction, and the respective plungers 32 and 32 which are in the form of short cylinders are slidably fitted in the through holes 31 and 31. Has been done. The cylindrical portion 30 is provided on its outer peripheral side with an annular groove that communicates the outer end portions of the through holes 31, 31, ... With the cylindrical portion 30, the outer peripheral surfaces on both sides of the annular groove are individually wound. It is rotatably fitted in the housing 10 in a state of being liquid-tightly sealed by rings 33a, 33a and the like. An annular space surrounded by the bottom surface of the annular groove and the inner peripheral surface of the housing 10 serves as a reaction force chamber 33. The reaction force chamber 33 is a pressure guide port formed by penetrating the housing 10 in and out.
It is connected via 15 to the discharge side of the vehicle speed sensor pump SP. The vehicle speed sensor pump SP is, for example, the above-mentioned Jitsuko Sho 60-3821.
A trochoidal pump called a hydraulic pump which is mounted at the output end of the transmission and is driven at a speed corresponding to the vehicle speed, similarly to the one disclosed in Japanese Patent Laid-Open No. 9, and which generates hydraulic pressure corresponding to the vehicle speed. Also, on the discharge side of the vehicle speed sensor pump SP,
A fixed throttle valve 7 is provided in parallel with the vehicle speed sensor pump SP to prevent an excessive hydraulic pressure from acting on the reaction force chamber 33.

Each of the plungers 32, 32 ... Has a hemispherical recess at the inner end thereof, while the output shaft 2 which is loosely fitted inside the cylindrical portion 30 for a proper length has a recess having a shape corresponding to the protrusion. But,
It is formed on the outer peripheral surface so as to be evenly distributed in the circumferential direction. When no steering torque is applied to the steering wheel and no relative angular displacement occurs between the steering wheel and the output shaft 3, the concave portion of the input shaft 2 has the mounting position of the plungers 32, 32 ... and the circumferential direction. Are positioned so that they are aligned with each other. As shown in FIG. 3, the projections at the tips of the plungers 32, 32 ... Are engaged with the recesses, respectively.

Also, one O-ring 33 wound around the outer periphery of the cylindrical portion 30.
A recirculation chamber 35, which is sealed on both sides in the axial direction by the a and the like, and the oil seat 34 which is fitted into the housing 10 and is in sliding contact with the outer periphery of the output shaft 3, is connected to the hydraulic control valve 60 of the cylindrical portion 30. And is arranged in parallel with the reaction force chamber 33 on the opposite side. The recirculation chamber 35 has one end opened inside thereof, and a recirculation hole 16 formed by penetrating the cylindrical portion 30 in and out and a recirculation hole 17 formed by penetrating the input shaft 2 in and out, thereby forming an input shaft. It communicates with the hollow portion of No. 2 and through the hollow portion and the reflux chamber 64 to the oil tank T maintained at a low pressure. Return room 35
Are the through holes 31, 31 ...
It is in communication with each of. As shown in FIG. 2 and FIG. 3, the throttle holes 36, 36, ... Are in the forward / backward position where the plunger 32, 32 ... Engages the convex portion at the tip thereof with the concave portion on the outer periphery of the input shaft 2. Further, it is formed so as to open slightly closer to the outer circumference than these outer end portions.

Further, a communication oil passage 8 is provided between the outlet side of the recirculation port 14 of the hydraulic control valve and the inlet side of the pressure guide port 15 of the reaction force chamber 33, and these communicate with each other. In addition, a return port is provided in the middle of the communication oil passage 8.
Only when the pressure on the 14 side is higher than the pressure on the pressure guide port 15 side, there is provided a check valve 9 for allowing the return oil flowing out from the return port 14 to flow into the reaction force chamber 33 via the pressure guide port 15. There is.

In the hydraulic reaction force portion 1 configured as described above, the pressure oil discharged from the vehicle speed sensor pump SP and introduced into the reaction force chamber 33 passes through the throttle holes 36, 36 ... Formed in the through holes 31, 31 ,. It passes through and leaks into the recirculation chamber 35, and then recirculates to the oil tank T through the recirculation holes 16 and 17, the hollow portion of the input shaft 2 and the recirculation chamber 64. Therefore, the oil pressure in the reaction force chamber 33 depends on the vehicle speed sensor pump SP.
Changes depending on the level of generated hydraulic pressure and the level of flow resistance in the throttle holes 36, 36 ... When the steering torque is not applied to the steering wheel and the relative angular displacement does not occur between the input shaft 2 and the output shaft 3, the plungers 32, 32 ...
At the position shown in FIG. 3 and FIG. 3, the throttle holes 36, 36 ... Are open. At this time, the hydraulic pressure in the reaction force chamber 33 corresponds only to high and low vehicle speeds.
As a result of being pressed against the output shaft 3, the relative angular displacement between the shafts 2 and 3 is restrained by a force corresponding to the vehicle speed, and the steering torque is large enough to disengage the engagement of the plungers 32, 32. The control operation of the hydraulic control valve 60 is not performed until the hydraulic pressure reaches a certain level, and the steering assist force generated by the hydraulic cylinder S is substantially zero.
Kept in. Further, after the disengagement occurs, the throttle holes 36, 36, ... Are closed in accordance with the movement of the plungers 32, 32 .. accompanied with this, and as a result, the hydraulic pressure in the reaction force chamber 33 becomes higher than that before the disengagement.
The plungers 32, 32 ... Are pressed against the outer periphery of the input shaft 2 with a stronger force.

Further, the return port 14 of the hydraulic control valve 60 and the pressure introducing port of the reaction force chamber 33.
15 is communicated with the oil tank 8 through a check valve 9 provided in the interlocking oil passage 8. When the hydraulic pressure on the side of the return port 14 is higher than the hydraulic pressure on the side of the reaction chamber 33, the oil port 15 is connected to the oil tank. A part of the pressure oil flowing back to T passes through the communication oil passage 8 via the check valve 9 and flows into the reaction force chamber 33 side. Due to the action of the check valve 9, the reaction force chamber 33 is pressurized during low speed traveling when the discharge pressure of the vehicle speed sensor pump SP is low.

FIG. 4 is a graph showing the characteristics of the power steering apparatus according to the present invention, in which the vertical axis represents the pressure of the reaction chamber 33 and the horizontal axis represents the rotation speed of the vehicle speed sensor pump SP. The solid line indicates the pressure of the pressure oil flowing back from the return port 14 to the oil tank T, and the broken line indicates the pressure.

In the power steering apparatus according to the present invention, the vehicle speed increases, the rotation speed of the vehicle speed sensor pump SP reaches a predetermined rotation speed, and the discharge pressure is the pressure of the pressure oil that flows back from the return port 14 to the oil tank T. Pressure oil flowing out from the return port 14 passes through the check valve 9 by the operation of the check valve 9 and then flows into the reaction force chamber 33 via the pressure guiding port 15 until the hydraulic reaction force portion 1 becomes the plunger 32, The pressure in the reaction chamber 33 is maintained at a constant value so as not to lose the force pressing the outer circumference of the input shaft 2 ... Then, when the rotation speed of the vehicle speed sensor pump SP reaches a predetermined rotation speed and the discharge pressure becomes equal to or higher than the pressure of the pressure oil that recirculates from the recirculation port 14 to the oil tank T, the reaction force chamber via the check valve 9 is reached.
The pressure oil does not flow into 33, and the pressure in reaction chamber 33 increases as the rotation speed of vehicle speed sensor pump SP increases.

Due to such characteristics, in the vehicle equipped with the power steering apparatus according to the present invention, the pressure of the reaction force chamber 33 is low, and the return force is generated during low speed traveling when the hydraulic reaction force portion 1 exerts a small restraining force on the input shaft 2. Since the pressure of the pressure oil flowing back from the port 14 to the oil tank T acts on the reaction force chamber 33, the plungers 32, 32 ... Do not move outward in the radial direction and can be constantly pressed against the input shaft 2. .. and the input shaft 2 do not collide with each other during steering, and no hammering sound is produced.

In the present embodiment, the pressure return port of the reaction chamber 33 from the return port 14
Although the communication passage 8 is formed at 15, the communication passage 8 is not limited to this.
May be formed so that the recirculation chamber 64 or the recirculation chamber 35 and the reaction force chamber 33 are directly communicated with each other. Further, although the valve body 61 is formed on the input shaft 2 in the present embodiment, the present invention is not limited to this, and the valve body 61 is formed so as to surround the input shaft 2 and the valve body 61 is formed.
The 61 and the input shaft 2 may be connected. Further, in the present embodiment, the plungers 32, 32 ... Are mounted on the output shaft 3, but the present invention is not limited to this, and the plungers 32, 32 ... May be mounted on the casing 60.

〔effect〕

As described above in detail, in the power steering device according to the present invention, the valve body or the casing is configured by causing the pressure oil to flow from the return chamber of the hydraulic control valve to the hydraulic reaction chamber when the vehicle travels at low speed. The distance between the plunger and the plunger is suppressed, and there is no gap between them, so the tapping sound during steering at low speed is suppressed, and a comfortable steering feeling can be obtained.
The present invention has excellent effects.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a power steering apparatus according to the present invention, FIG. 2 is a partially enlarged view of FIG. 1 showing a structure of a hydraulic reaction force portion, and FIG. 3 is a view of FIG. Cross-sectional view taken along line III-III, 4th
FIG. 5 is a graph showing the characteristics of the power steering apparatus according to the present invention, and FIG. 5 is a transverse sectional view of the hydraulic reaction force portion in the conventional power steering apparatus. DESCRIPTION OF SYMBOLS 1 ... Hydraulic reaction force part, 2 ... Input shaft, 3 ... Output shaft, 8 ... Communication oil passage, 9 ... Check valve, 10 ... Housing, 14 ... Reflux port, 30
… Cylindrical part, 31… Through hole, 32… Plunger, 33… Reaction chamber,
SP ... Vehicle speed sensor pump

Claims (1)

(57) [Scope of utility model registration request] 1. A relative relationship between a valve body formed or connected to an input shaft and a casing formed or connected to an output shaft when hydraulic pressure is supplied to an actuator that generates a steering assist force, when a steering wheel is operated. A plunger provided movably on the casing or a part of the output shaft, and a reaction force chamber formed on one side of the plunger, which is equipped with a hydraulic control valve that controls according to movement, The return oil from the actuator is provided with a hydraulic reaction force portion that applies a restraining force according to the introduced hydraulic pressure to the chamber between the valve body and the casing or the output shaft via the plunger to restrain the relative movement. In a power steering apparatus for feeding a low pressure source through a return chamber of the hydraulic control valve, a communication oil passage communicating between the outlet side of the return chamber and the reaction force chamber, and the communication oil passage, The pressure of the reaction chamber is the pressure of the reflux chamber Ri is lower, the hydraulic control valve power steering apparatus characterized by pressure oil reflux chamber to and a check valve for flow through into said reaction force chamber.