JPH02169371A - Power steering - Google Patents

Abstract

PURPOSE:To make improvements in a steering feeling by installing a hydraulic reaction part, which restrains any control action of a hydraulic control valve controlling a hydraulic pressure feed to a hydraulic actuator, at the upstream side of a variable throttle part at the discharge side of a car speed sensor pump generating hydraulic pressure corresponding to a car speed. CONSTITUTION:A power steering has a hydraulic control valve 6 being operated according to the twist of a torsion bar 4, connecting both input and output shafts 2, 3, to be generated when steering torque is added, and controls the feed or exhaust of pressure oil to or from both oil chambers of a hydraulic cylinder by operation of this hydraulic control valve 6, thereby giving stering assist force to a rack shaft 5. In addition, it has a hydraulic reaction part restraining relative angle displacement between these input and output shafts 2, 3 according to a car speed. In this case, there is provided with a car speed sensor pump SP which generates hydraulic pressure corresponding to the car speed, and a variable throttle part 7 inclusive of a spool 71 being displaced after receiving the feed hydraulic pressure for the hydraulic cylinder is installed interposingly in the point midway in its discharge oil passage 80. Then, a reaction chamber 33 of the hydraulic reaction part 1 is set up in this discharge oil passage 80 at the upstream side of this variable throttle part 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic power steering device in which a hydraulic actuator is the source of the steering assist force, and more specifically, the present invention relates to a hydraulic power steering device in which a hydraulic actuator is the source of the steering assist force. The present invention relates to a power steering device that includes a hydraulic reaction force section that restricts the control operation of a hydraulic control valve that controls supply oil pressure with a force that corresponds to vehicle speed.

[Prior art]

A hydraulic power steering device that uses a hydraulic actuator such as a hydraulic cylinder disposed in a steering mechanism as a source of steering assist force is, for example, an input shaft connected to a steering wheel and an input shaft that is operatively connected to a steering wheel. The output shaft is coaxially connected to the output shaft via a torsion bar, and a hydraulic control valve for controlling the hydraulic pressure supplied to the hydraulic actuator is provided at this connecting part. It includes a cylindrical casing that rotates in conjunction with one of the two wheels, and a valve body that is coaxially fitted into the cylindrical casing and rotates in conjunction with the other, and a throttle formed between these is connected to the hydraulic actuator and the hydraulic pressure generator. It is configured to be interposed between the source and the source. When a steering torque is applied to the steering wheel, a relative angular displacement occurs between the valve body and the casing in accordance with the accompanying twist of the torsion bar, and the throttle opening degree generated in the throttle portion is: While it changes in response to this relative angular displacement, the hydraulic pressure supplied to the hydraulic actuator corresponds to the size of the throttle opening.
The hydraulic actuator generates a steering assist force corresponding to the direction and magnitude of the steering torque, thereby assisting the force required to operate the steering wheels for steering.

It is generally known that the magnitude of the force required to operate the steering wheel for steering corresponds to the magnitude of the reaction force acting on the steered wheels from the road surface, and that the magnitude of this reaction force corresponds to the slowness of the vehicle speed. ing. On the other hand, in the power steering device configured as described above,
The correspondence relationship between the steering torque applied to the steering wheels and the steering assist force generated by the hydraulic actuator is determined only by the torsional characteristics of the torsion bar. Therefore, if this torsion bar is selected based on a large reaction force when stopped or running at low speeds, steering will be performed with a small force applied to the steering wheel when running at high speeds, resulting in deterioration of straight-line stability. On the other hand, if the torsion bar is selected based on high-speed running, there is a problem in that sufficient steering assist force cannot be obtained when the vehicle is stopped or when running at low speed.

To solve this problem, the hydraulic control valve is installed in parallel with the connecting part between the input shaft and the output shaft, and a hydraulic reaction force that increases or decreases depending on the vehicle speed is applied between the two shafts. The control operation of the hydraulic control valve that occurs in response to the relative angular displacement of
A power steering device has been developed that includes a hydraulic reaction force section that restrains the vehicle with a strong force at high speeds and with a weak force at low speeds.

FIG. 6 is an enlarged cross-sectional view of a main part showing one side of a conventional hydraulic reaction force section. The hydraulic reaction force section is constructed in a cylindrical housing 10 that supports both shafts at a connecting portion between the human power shaft and the output shaft. 30 in the figure is, for example, a cylindrical portion coaxially connected to the connecting end of the output shaft, and this is rotatably fitted into the housing 10. A reaction force chamber 33 is formed between the circumferential surface and the annular space having an appropriate width in the axial direction. A portion of the input shaft 2 is loosely fitted inside the cylindrical portion 30, and a plurality of recesses are formed at equal intervals in the circumferential direction on the outer circumferential surface of the input shaft 2, as shown. The cylindrical portion 30 also has through holes 3 which penetrate the cylindrical portion 30 in the radial direction and have the same number as the recessed portions.
1.31... are formed equidistantly in the circumferential direction, and each of these through holes 31, 31... has a separate plunger 32 slidably slidable along the through holes 31, 31... .32・
... is fitted inside. These plungers 32.32
... each has a hemispherical convex portion on the inner end,
These convex portions are adapted to engage with the recessed portions on the outer periphery of the input shaft 2 as shown.

4 in the figure is a torsion bar that connects the input shaft 2 and the output shaft, and when a steering torque is applied to the steering wheel, a relative angular displacement occurs between the two shafts due to the torsion of the torsion bar 4. As described above, the hydraulic pressure supplied to the hydraulic actuator for assisting steering is controlled by the operation of a hydraulic control valve (not shown) configured at a connecting portion of the shaft. On the other hand, in the hydraulic reaction force section, the plungers 32, 32... are pressed radially inward by the hydraulic pressure inside the reaction force chamber 33 acting on their respective outer end surfaces, The convex portion of the input shaft 2 is engaged with the concave portion on the outer periphery of the input shaft 2. Therefore, the relative angular displacement between the input shaft 2 and the cylindrical portion 30 forming a part of the output shaft is restrained by a force corresponding to the oil pressure.
It is as if a reaction force corresponding to this oil pressure is acting on the output shaft side, and the steering torque applied to the human power shaft 2 via the steering wheel acts against the oil pressure and causes the plungers 32, 32, . . .
The hydraulic actuator cannot generate a steering assist force until the relative angular displacement reaches a size that pushes up radially outward, and the hydraulic control valve does not operate. That is, by introducing hydraulic pressure that increases or decreases depending on the vehicle speed into the reaction force chamber 33, appropriate rigidity is imparted to the steering wheel during high-speed running, and straight-line stability is improved.
At the same time, it is possible to obtain sufficient steering assist force when stopped and when running at low speed, and to reduce the force required to operate the steering wheel as much as possible.

Various proposals have been made as means for making the hydraulic pressure introduced into the reaction force chamber 33 correspond to the vehicle speed.
In the power steering device disclosed in Publication No. 63, an oil passage connected to a hydraulic tank via a variable throttle and a fixed throttle is provided on the discharge side of a hydraulic pump that generates a predetermined oil pressure, and both of the above-mentioned oil passages are connected in the middle of the core oil passage. The hydraulic pressure between the throttles is used as the hydraulic pressure introduced into the reaction force chamber 33, and the throttle opening degree of the variable throttle is changed according to the detection result of the vehicle speed, so that the introduced hydraulic pressure corresponds to the vehicle speed. , also, special public service 53-45
Publication No. 571 and Utility Model Publication No. 60-382 by the applicant
Publication No. 19 etc. describes the hydraulic pressure generated by a hydraulic pump (gear pump in the former case, trochoid pump in the latter case) that is attached to the output shaft of the transmission and driven at a speed corresponding to the vehicle speed, and the hydraulic pressure corresponding to the vehicle speed. A structure is disclosed in which this oil pressure is used as a hydraulic pressure and introduced into the reaction force chamber 33.

[Problem to be solved by the invention]

FIG. 7 is a graph showing the correlation between the steering torque applied to the steering wheel in the power steering system equipped with the hydraulic reaction force section configured as described above and the steering assist force generated by the steering assist hydraulic actuator. It is. As shown in this figure, in the conventional power steering system, due to the operation of the hydraulic reaction force unit as described above, the steering torque is maintained at approximately O until it reaches a predetermined level, and then increases rapidly. Since the steering assist force is obtained and the hydraulic pressure introduced into the reaction force chamber 33 is made to correspond to the vehicle speed, the rising point of the steering assist force is on the side where the steering torque increases as the vehicle speed increases. A characteristic that transitions to is obtained.

Now, when considering the actual steering sensation, it is desirable that the stiffness of the steering wheel increases as the steering angle increases, but in conventional power steering systems, after the steering torque applied to the steering wheel exceeds the above-mentioned rising point, As shown in the figure, the steering assist force increases rapidly and the stiffness of the steering wheel remains approximately constant, so it is inevitable that the steering feel will feel a little strange. In order to eliminate this sense of discomfort, a characteristic is required in which the steering assist force shows a relatively gradual increase after exceeding the rising point. Such characteristics are described in the above-mentioned Japanese Patent Application Laid-open No. 61
In the power steering device disclosed in Publication No. 200063, this can be realized by changing the aperture opening of the variable aperture according to not only the detected result of the vehicle speed but also the detected result of the steering amount. The configuration of the control system to change the opening becomes more complex, and in addition to the vehicle speed sensor, a steering angle sensor is required to detect the amount of steering, which increases the risk of malfunctions in various parts. be. On the other hand, when the hydraulic pressure generated by a hydraulic pump that generates hydraulic pressure corresponding to the vehicle speed (hereinafter referred to as vehicle speed sensor pump) is used as the introduced hydraulic pressure, there is no risk of the malfunction occurring.
It was thought that it would be impossible to achieve the desired characteristics as described above.

The present invention has been made in view of the above circumstances, and provides a power steering system that uses a vehicle speed sensor pump as a source of hydraulic pressure introduced into a hydraulic reaction force section and achieves desired characteristics of fate with a simple configuration. The purpose is to provide

[Means for Solving the Problems] The power steering device according to the present invention supplies hydraulic pressure to a hydraulic actuator that generates a steering assist force to the relative position that occurs between the valve body and the casing as the steering wheel is operated. A hydraulic reaction force unit includes a hydraulic control valve that controls the movement according to the movement, and applies a reaction force between the valve body and the casing according to the level of the oil pressure introduced into the reaction force chamber, and restrains the relative movement. A power steering device comprising: a vehicle speed sensor pump that generates hydraulic pressure corresponding to high and low vehicle speed; and a vehicle speed sensor pump disposed in the middle of a discharge oil path of the pump, and a pump that supplies hydraulic pressure to the hydraulic actuator on one side thereof. It has a spool that moves in response to pressure, and a variable throttle that changes the opening degree of the throttle in accordance with the movement of the spool, and the reaction force chamber is located in the middle of the discharge oil path on the upstream side of the variable throttle. It is characterized by being located at

[Function] In the present invention, the hydraulic pressure introduced into the reaction force chamber is the hydraulic pressure generated by the vehicle speed sensor pump against the flow resistance in the variable throttle, and when the spool is at the same movement position. , varies in height depending only on the vehicle speed, while at the same vehicle speed, the movement position of the spool,
That is, the height varies depending on the level of the oil pressure supplied to the hydraulic actuator.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments thereof. FIG. 1 is a longitudinal sectional view showing the main parts of a power steering device 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 the input shaft 2
They are coaxially connected via a torsion bar 4 inserted into the hollow part of the. One end portion of the manpower shaft 2 which projects to the outside of the housing 10 by a suitable length is connected to a steering wheel (not shown), and a steering torque applied to the steering wheel is transmitted to the manpower shaft 2. Further, the output shaft 3 is operatively connected to a steering wheel (not shown) so that steering can be performed according to the amount of rotation of the output shaft 3. For example, in a vehicle equipped with a rack and pinion type steering mechanism, this connection is made using a pinion 3 formed on the outer periphery of the midway part of the output shaft 3, as shown in the figure.
This is achieved by meshing the output shaft 3 with the rack shaft 5 in the steering mechanism. In this case, the rotation of the output shaft 3 is converted into a movement in the axial direction of the rack shaft 5 via the pinion 3a. The steering is done by Further, a disk-shaped piston coaxially fixed to the rack shaft 5 is disposed in the middle of the rack shaft 5, and a cylindrical housing surrounding the rack shaft 5 is liquid-tightly sealed over a predetermined length. A hydraulic cylinder S (see Fig. 2) for assisting steering is configured by being fitted inside the formed cylinder. A corresponding amount of movement power is added to assist with the force required for steering.

Now, the output shaft 3 is provided with a cylindrical part 30 coaxially connected to the input shaft 2 at the end thereof on the side connected to the input shaft 2.
The connecting end portion of is loosely fitted into the cylindrical portion 30 at an appropriate length. A hydraulic control valve 6 that controls the hydraulic pressure supplied to the hydraulic cylinder S includes a short cylindrical casing 60 that is rotatably fitted into the housing 10 and a casing 60 that is fitted inside the casing 60 and is connected to the input shaft. 2, and a valve body 61 formed in a part of the valve body 61. FIG. 2 is an enlarged cross-sectional view taken along the line ■--■ in FIG.

On the inner peripheral surface of the casing 60, a plurality of long grooves 62, 62, . , a detent pin 30a driven on the outer periphery of the tip of the cylindrical portion 30;
A part of the output shaft 3 is engaged with the output shaft 3, and rotates as the output shaft 3 rotates. Further, on the outer peripheral surface of the valve body 61,
The long grooves 63, 63, which are the same in number as the long grooves 62, 62, and have a predetermined width, extend over an appropriate length in the axial direction,
They are equally spaced in the circumferential direction. In addition, the valve body 6
It goes without saying that 1 rotates in conjunction with the human-powered shaft 2. The casing 60 and the valve body 61 have a predetermined structure in which the long grooves 62 and 63 are arranged in a staggered manner, and when the torsion bar 4 is not twisted, the long grooves 62 and 63 are adjacent to each other on both sides in the circumferential direction. They are positioned so that they communicate with each other through a gap. The long grooves 62, 62 of the casing 60...
- is each separate communication hole 1 that penetrates the casing 60 inside and outside
5.16 communicates with the respective annular grooves on the outer periphery of the casing 60, and is alternately connected to both extraction chambers of the hydraulic cylinder S through separate pressure inlet ports 11.12 passing through the housing 10 from inside to outside. It is communicated with. On the other hand, half of the long grooves 63, 63, etc. of the valve body 61, which are located at every other position, are connected to the casing 60 by the communication holes 17, which have one end opened on the outside and penetrate the casing 60 from inside to outside. A hydraulic pump P, which is a hydraulic pressure ordering source, is connected through an inlet 13 that communicates with the annular groove on the outer periphery and further penetrates the housing 10 from inside to outside.
The remaining half is connected to the hollow part of the input shaft 2 through a communication hole 18 that has one end opened at the bottom of each valve body 61 and passes through the valve body 61 from inside to outside. A reflux chamber 64 (see FIG. 1) formed on the side;
and a casing 60 with one end opened inside the reflux chamber 64.
It is connected to an oil tank T maintained at a low pressure state via a reflux port 14 that penetrates both inside and outside.

The operation of the hydraulic control valve 6 having the above configuration will be briefly explained. When a steering torque is applied to the steering wheel, the input shaft 2 connected thereto tries to rotate in accordance with the rotation of the steering wheel, while the output connected to the steering wheel via the pinion 3a and the rack shaft 5 is Since the rotation of the shaft 3 is restricted by the road reaction force acting on the wheels, the torsion bar 4 that connects both shafts is twisted in accordance with the steering torque, and a part of the input shaft 2 is twisted. A relative angular displacement occurs between the valve body 61 that has been rotated 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 is
As one increases, the other decreases, and the pressure oil introduced from the hydraulic pump P into the long grooves 63, 63... through the inlet 13 and the communication hole 17 passes through the gap on the side where the area increases. , into the adjacent long grooves 62, 62 on the same side, and the communication hole 15 and the pressure guiding port 11, or the communication hole 16.
The oil is supplied to one oil chamber of the hydraulic cylinder S through the pressure guiding port 12. Further, the oil in the other oil chamber of the hydraulic cylinder S is transferred to the pressure guiding port 12 and the communication hole 16, or the pressure guiding port 11.
and through the communication hole 15, it flows back into the long grooves 62, 62, which are different from the long grooves 62, 62, and furthermore, the areas of the gaps on both sides of these long grooves 62, 62... It passes through the gap on the enlarged side and is introduced into the long grooves 63, 63 that communicate with the hollow part of the input shaft 2, and then flows through the communication hole 18, the hollow part, the reflux chamber 64, and the reflux port 14 to the oil tank. Reflux to T. As a result, a pressure difference is generated between both oil chambers of the hydraulic cylinder S, and a steering assist force corresponding to this 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 manner of change in the throttle area that occurs in the gap between the long grooves 62 and 63 in accordance with the relative angular displacement, and this change manner is dependent on the manner in which the throttle area of the torsion bar 4 changes. Uniquely corresponds to the twist mode. Therefore, the correspondence between the steering torque applied to the steering wheel and the steering assist force generated by the hydraulic cylinder S in response to this is determined only by the torsion characteristics of the torsion bar 4, and as mentioned above, the straight-line stability during high-speed driving is achieved. This may result in poor steering performance or insufficient steering assist force when driving at low speeds.

The hydraulic reaction force section 1 applies a force corresponding to the vehicle speed between the human power shaft 2 and the output shaft 3 to restrain the relative angular displacement, and solves the above-mentioned difficulty. It is constructed around the cylindrical portion 30 that is connected to the end portion. FIG. 3 is an enlarged view of a main part showing the structure of the hydraulic reaction force part l, and FIG. 4 is a cross-sectional view taken along the line IV--IV in FIG.

A plurality of through holes 31, 31... are formed in the cylindrical part 30 and are equally spaced in the circumferential direction, passing through the cylindrical part 30 in the radial direction. , short cylindrical plungers 32, 32, . . . are slidably fitted therein. These plungers 32.32...
each has a hemispherical convex portion protruding from the inner end thereof, and on the other hand, the outer periphery of the output shaft 2 loosely fitted inside the cylindrical portion 30 has a shape corresponding to the convex portion. The concave portions are formed in an evenly spaced manner. In the human power shaft 2, 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 recessed portion is connected to the plunger 3.
It is positioned so as to be circumferentially aligned with the mounting position of 2.32.... Further, an annular groove communicating with the outer ends of the through holes 31, 31, etc. is formed on the outer circumferential side of the cylindrical portion 30, and the cylindrical portion 30 has sealing members such as O-rings on both sides of the annular groove. The housing 10 is sealed liquid-tightly.
The reaction force chamber 33 is rotatably fitted into the annular groove and the inner circumferential surface of the housing 10 and forms an annular space surrounded by the annular groove and the inner circumferential surface of the housing 10 . Therefore, the plunger 32.
32... are pressed radially inward by the pressure inside the reaction force chamber 33 acting on their respective outer end faces, and as shown in FIGS. The recesses are respectively engaged, and between the input shaft 2 and the cylindrical part 30,
That is, the relative angular displacement between the input shaft 2 and the output shaft 3 is restrained by a force corresponding to the pressure inside the reaction force chamber 33 due to this engagement.

In the power steering device according to the present invention, the reaction force chamber 33
is connected to the discharge side of the vehicle speed sensor pump SP via a pressure guiding port 20 formed by penetrating the housing 10 inwardly and outwardly, and also has a feature of the present invention configured as described below on the outside of the housing 10. It is connected to an oil tank T via a barrel variable throttle section 7.

The discharge oil passage 8 of the vehicle speed sensor pump sp is connected to the reaction force chamber 33.
The reaction force chamber 33 consists of a first discharge oil passage 80 connected to the oil tank T via the variable throttle section 7 and a second discharge oil passage 81 connected to the oil tank T via the fixed throttle 82. It is disposed in the middle of the first discharge oil passage 80 and upstream of the variable throttle part 7 . Therefore, the oil pressure in the reaction force chamber 33 is the oil pressure generated by the vehicle speed sensor pump SP against the flow resistance in the fixed throttle 82 and the variable throttle section 7, and depending on the throttle opening degree in the variable throttle section 7, The oil pressure inside the reaction force chamber 33 changes.

In addition, the vehicle speed sensor pump SP is based on the above-mentioned Utility Model Act
Similar to the one disclosed in Publication No. 219, it is a known hydraulic pump such as a trochoid pump, which is attached to the output end of a transmission, is driven at a speed corresponding to the vehicle speed, and generates hydraulic pressure corresponding to the vehicle speed, A description of its structure will be omitted.

The variable throttle part 7 is a cylinder integrally formed on the outside of the housing lO, extending from the configuration position of the hydraulic control valve 6 to the configuration position of the hydraulic reaction force part l, and having an axis substantially parallel to the housing lO. The housing 70 has a cylindrical shape and a cylindrical spool 71 that is fitted into the housing 70 so as to be slidable in the axial direction. It is divided into two oil chambers 72 and 73.

One oil chamber 72 located on the side of the hydraulic control valve 6 is formed on the outer periphery of the casing 60 of the hydraulic control valve 6, and is led to an annular groove connected to the hydraulic pump P via the introduction hole 13 as described above. The other oil chamber 73 is communicated with the reaction force chamber 33 of the hydraulic reaction force section 1 through the oil passage hole 22, and the oil chamber 73 is The housing 70 is connected to the oil tank T through a reflux port 23 formed through the housing 70 inside and outside. It goes without saying that the oil passage hole 22 and the reflux port 23 form a part of the first discharge oil passage 80. The spool 71 is pressed toward the oil chamber 72 by a coil spring 74 interposed between the spool 71 and the end wall of the oil chamber 73. It slides against the pressing force of the coil spring 74 acting on the other end surface depending on the level of oil pressure. As shown in FIGS. 1 and 2, the oil passage hole 22 has an opening inside the oil chamber 73 that is partially blocked as the spool 71 slides toward the core oil chamber 73. A tapered portion 71a is formed at the end of the spool 71 on the side of the oil chamber 73 so that the spool 71 is gradually closed.

In the power steering system according to the present invention configured as described above, the sliding movement of the spool 71 in the variable throttle section 7 occurs in response to an increase in the oil pressure in the oil chamber 73, and this increase in oil pressure is controlled by the oil pressure control. What occurs as the relative angular displacement between the casing 60 and the valve body 61 of the valve 6 increases is clear from the operation of the hydraulic control valve 6 as described above. Furthermore, if the oil passage hole 22 is blocked due to the sliding of the spool 71,
Since the hydraulic pressure in the reaction chamber 33 located upstream of this increases, the hydraulic reaction force generated in the hydraulic reaction force section 1 increases as the relative angular displacement increases. Therefore, in the state where the relative angular displacement is not occurring, the hydraulic reaction force generated by the hydraulic reaction force part l to restrain the control operation of the hydraulic control valve 6 is the hydraulic pressure generated by the vehicle speed sensor pump SP according to the vehicle speed. Correspondingly, it increases only in response to an increase in vehicle speed, while in a state where the relative angular displacement is occurring, it increases in response to an increase in this relative angular displacement, that is, an increase in the steering torque applied to the steered wheels.

FIG. 5 is a graph showing the increasing characteristic of the steering assist force in the power steering device according to the present invention. In the power steering device according to the present invention, until the steering torque applied to the steering wheels reaches a predetermined torque, the input shaft 2 and the output The relative angular displacement with respect to the shaft 3 is restricted, and the steering assist force generated by the hydraulic cylinder S is kept at approximately zero. Note that, as in the conventional power steering device, the magnitude of the predetermined torque corresponds to the vehicle speed. On the other hand, the steering torque applied to the steering wheel exceeds the predetermined torque, and the relative angular displacement between the human power shaft 2 and the output shaft 3 is caused by the plunger 32, 32...
, the spool 71 of the variable aperture section 7
moves as described above and the oil passage hole 22 is closed, so the hydraulic reaction force generated by the hydraulic reaction force section 1 increases as the relative angular displacement increases, that is, as the steering torque increases. However, the increase in the steering assist force after the predetermined torque is exceeded does not occur suddenly as in the conventional power steering system, but occurs gradually as shown in FIG. 5. As a result, in a vehicle equipped with the power steering device according to the present invention, a hydraulic reaction force that increases or decreases depending on the vehicle speed is applied to the steering wheel.
This not only improves straight-line stability when driving at high speeds, but also allows for easier steering wheel operation when driving at low speeds and when stopping.In both cases, the stiffness of the steering wheel increases as the steering force increases. The desired steering feeling is achieved.

Note that the hydraulic reaction force section 1 is not limited to the structure shown in FIGS. 1 and 3, and for example,
As disclosed in Japanese Patent No. 63061, a radially outward protrusion is provided at the end of the input shaft 2, and both sides of the protrusion are held by plungers to apply a hydraulic reaction force, etc. The hydraulic control valve 6 is not limited to the rotary type shown in FIGS. 1 and 2, and the hydraulic control valve 6 is not limited to the rotary type shown in FIGS. Other configurations may be used, such as one in which the feed oil pressure is controlled.

In addition, in this embodiment, the variable throttle part 7 is formed on the outside of the housing 10 that houses the hydraulic control valve 6 and the hydraulic reaction force part 1, and the variable throttle part 7 is formed integrally therewith. Needless to say, this is not the only option.

〔effect〕

As described in detail above, in the power steering system according to the present invention, the hydraulic reaction force portion that restrains the control operation of the hydraulic control valve that controls the hydraulic pressure supplied to the hydraulic actuator for steering assistance is configured to control the hydraulic pressure corresponding to the vehicle speed. The vehicle speed sensor pump is provided on the discharge side of the vehicle speed sensor pump that generates the pressure, and is located upstream of a variable throttle section that is equipped with a spool that receives the feed oil pressure on one side and moves.
The hydraulic reaction force generated by the hydraulic reaction force changes depending on the vehicle speed.
It changes in size depending on the amount of steering torque applied to the steering wheel.
The present invention has excellent effects, such as providing a desirable steering feeling in which the stiffness of the steering wheel increases as the steering torque increases.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view showing the main parts of the power steering device according to the present invention, Fig. 2 is a cross-sectional view taken along the line ■-■ of Fig. 1 showing the configuration of the hydraulic control valve, and Fig. 3 is the hydraulic pressure control valve. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3; FIG. 5 is a partially enlarged view of FIG. 1 showing the configuration of the reaction force section; FIG. FIG. 6 is a cross-sectional view of a hydraulic reaction force section in a conventional power steering device, and FIG. 7 is a graph showing characteristics of increase in steering assist force in a conventional power steering device. l...Hydraulic reaction force part 2...Manpower shaft 3...Output shaft 6...Hydraulic control valve 7...Variable throttle part 8
...Discharge oil path 30...Cylindrical part 32...Plunger 33...Reaction force chamber 70...Housing
71...Spool 74...Coil spring SP・
...Vehicle speed sensor pump patent Applicant: Koyo Seiko Co., Ltd. Agent: Patent attorney: Noboru Kono

Claims (1)

[Claims] 1. A hydraulic control valve that controls the hydraulic pressure supplied to a hydraulic actuator that generates steering assist force in accordance with the relative movement that occurs between the valve body and the casing as the steering wheel is operated. In the power steering device, the power steering device is provided with a hydraulic reaction force section that applies a reaction force between the valve body and the casing according to the level of hydraulic pressure introduced into the reaction force chamber, and restrains the relative movement. A vehicle speed sensor pump that generates hydraulic pressure corresponding to the height of and a variable throttle that changes the opening degree of the throttle in accordance with the movement position of the spool, and the reaction force chamber is located upstream of the variable throttle in the middle of the discharge oil path. A power steering device featuring: