JPH1016800A - Power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To collect dirt outside a filter and facilitate cleaning of the dirt by forming a periphery surface of a filter frame in spherical surface and press- fitting the spherical surface shaped frame into slanted passage hole. SOLUTION: A mesh 100 is fit in a filter 99 and an outer side frame 102 is formed in a shape that it is spherical shaped as a whole and upper and lower part, of the sphere is cut in plane. A flow passage through which plane surfaces 102a, 102b are penetrated and the mesh 100 is assembled in nearly middle of the flow passage 104. Outer diameter of the spherical frame 102 of the filter 99 is larger than inner diameter of a large diameter part 62a of a supply passage hole 62 of a hydraulic reaction control valve 50 and the filter 99 is fixed in the large diameter part 62a by press fitting it. Whereby, cleaning of dirt collected by press fitting the filter at a steering control valve side can be facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering apparatus, and more particularly, to a power steering apparatus having a steering force control valve for controlling a pressure or a flow rate according to a running condition of a vehicle to obtain a desired steering force. It is about.

[0002]

2. Description of the Related Art A power steering apparatus switches a flow path switching valve in response to an input applied to a steering handle, and introduces pressure oil discharged from an oil pump into one chamber of a power cylinder. The other cylinder chamber communicates with the tank to recirculate the oil in this chamber, thereby operating the power cylinder to apply a steering assist force to the steered wheels. In such a power steering device, when the ground resistance is large, such as when the vehicle is stationary or running at low speed, it is required to have a characteristic of generating a steering assist force as large as possible so as to reduce the force required to operate the steering wheel. On the other hand, at the time of high-speed running, it is required to provide a steering wheel with appropriate rigidity and to improve the straight running stability so that the steering assist force is as small as possible.

In order to obtain the preferable steering force characteristics as described above, a power steering device provided with a steering force control valve for controlling a pressure or a flow rate according to a traveling condition such as a traveling speed of a vehicle has been known. I have. For example, in a power steering device provided with a hydraulic reaction force mechanism, a reaction oil pressure is diverted from a high pressure passage from an oil pump to a power cylinder via a flow path switching valve, and is used as a hydraulic reaction force control valve ( The steering force is controlled by a steering force control valve and introduced into the hydraulic reaction chamber to act on the reaction force plunger, thereby selectively restricting the input / output shaft to obtain a desired steering force.

In the case where the hydraulic reaction force control valve is integrated with the valve housing of the power steering apparatus, FIG. 7 (this figure shows the hydraulic reaction force control valve of the power steering apparatus). As shown in the figure, a connecting surface to the valve housing is shown), and a connecting surface 167 of the hydraulic reaction force control valve 150 with the valve housing communicates with an inlet port for introducing the pressure oil discharged from the oil pump to the flow path switching valve. Supply passage hole 162, the passage hole 16 communicating with the passage to the hydraulic reaction chamber
There are three passage holes, a return passage hole 164 that communicates with the tank via an outlet port provided in the zero and the valve housing. Further, each of these passage holes 160, 1
O-ring grooves 161, 163 and 165 as seal members are formed around 62 and 164, respectively. Therefore, each of the passage holes 160, 162, 163
From the relationship of the space, forced to not give disposed at a position deviated from the axis O ₁ of the hydraulic reaction force control valve 150, therefore,
Each of the passage holes 160, 162, 163 must be formed so as to be inclined with respect to the joint surface 167 of the hydraulic reaction force control valve 150 to the valve housing.

[0005]

In order to prevent foreign matter such as dust from entering the inside of the hydraulic reaction force control valve 150, a filter is press-fitted into the supply passage hole 162 communicating with the input port. However, it is difficult to press-fit this filter into the oblique passage hole 162. Therefore, conventionally, as shown in FIG. 8, the inside of the passage hole 162 is a diagonal passage 162b, and only the inlet side is a hole 162 perpendicular to the joint surface 167 of the valve housing.
The filter 199 having a cylindrical outer shape is pressed into the vertical hole 162a. In the case of such a configuration in which the oblique passage hole 162b and the vertical filter press-fit hole 162a are combined, there is a problem that the number of processing steps of the hole is increased and the cost is high.

Further, as described above, in order to avoid a configuration in which oblique holes and orthogonal holes are combined, as shown in FIG. 9, a valve housing 13 of a power steering device is used.
There has also been proposed a configuration in which a filter 199 having a cylindrical outer shape is press-fitted into a passage 168 connected to an oil pump on the second side. However, with such a configuration, there is a problem that dust cannot be cleaned because dust accumulates inside the filter 199 from the flow direction of the pressure oil.

SUMMARY OF THE INVENTION The present invention has been made in order to eliminate the disadvantages of the above-mentioned conventional configurations, and aims to reduce man-hours for machining a passage hole formed in a steering force control valve and to improve workability at the time of press-fitting a filter. It is another object of the present invention to provide a power steering apparatus provided with a steering force control valve capable of easily cleaning dust accumulated on a filter.

[0008]

A power steering apparatus according to the present invention includes a steering force control valve for controlling pressure or flow rate.
The steering force control valve is provided integrally with a steering valve housing (a valve housing of a power steering device main body). The steering force control valve is formed with a passage hole in an inclined direction for introducing pressure oil into the valve. It communicates with a passage branched from a high-pressure oil passage that sends pressure oil from an oil pump to a passage switching valve
A filter is press-fitted into an oil passage extending from the branch passage to the passage hole. In particular, an outer peripheral surface of a frame of the filter is formed in a spherical shape, and the spherical frame is formed in the inclined passage. It was pressed into the hole.

In the power steering apparatus having the above-described structure, since the filter frame is spherical, it can be easily pressed into the oblique passage hole, and there is no restriction due to the direction.
Extremely good workability. Further, since the filter is press-fitted into the steering force control valve, dust in the pressurized oil diverted and supplied from the power steering device side is collected outside the filter, so that cleaning is easy.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments shown in the drawings. FIG. 1 is a longitudinal sectional view of a power steering device according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a hydraulic reaction force control valve (steering force control valve) provided integrally with the power steering device. is there. This embodiment relates to an integral type power steering device provided with a hydraulic reaction force mechanism, in which a piston 6 is slidably fitted in a cylinder portion 4 of a gear housing 2, and the inside of the cylinder portion 4 is Is divided into two pressure chambers 8 (one of which is not shown). A rack 12 is formed on one side surface (the lower surface in FIG. 1) of the piston 6, and a sector gear 16 integrally provided on a sector shaft 14 is meshed with the rack 12, so that the piston 6 reciprocates. Accordingly, the sector gear 16 and the sector shaft 14 rotate forward and backward. Then, the rotation of the sector shaft 14 is transmitted to the steered wheels via a link mechanism (not shown) to turn the vehicle.

A worm shaft (output shaft) 22 is screwed to the shaft center of the piston 6 via a ball screw 20 for circulating a large number of balls 18. A number of balls 18 roll in the groove 22 to move the piston 6 forward and backward. One end (right end in FIG. 1) 22a of the worm shaft 22
Has a large-diameter cylindrical shape, and in this large-diameter cylindrical portion 22a,
An end of a stub shaft (input shaft) 26 that is rotated by a steering handle (not shown) is fitted. One end (not shown) of the worm shaft 22 and the stub shaft 26 is press-fitted into the inner diameter of the worm shaft 22, and the other end 28 a is fitted inside the stub shaft 26 and fixed by the pin 30. They are connected via a torsion bar 28 so that relative rotation at a predetermined angle is allowed. The worm shaft 22 and the stub shaft 26 that are integrally connected are rotatably supported via bearings 34 and 36 in a valve housing 32 fixed to an end of the gear housing 2.

A valve sleeve (outer valve) 38 is formed directly on the inner peripheral surface of the large-diameter cylindrical portion 22a provided at the end of the worm shaft 22, while a cylindrical sleeve is formed on the outer peripheral surface of the stub shaft 26. A valve rotor (inner valve) 40 is fitted and connected by a pin 42 so as to rotate integrally. A rotary type control valve (flow path switching valve) 44 is formed by the valve sleeve 38 and the valve rotor 40. At a neutral position of the flow path switching valve 44, the oil is discharged from an oil pump (not shown) and discharged from an inlet port 46. The oil introduced into the flow path switching valve 44 returns to the oil tank via the outlet port 48, and when the flow path switching valve 44 is switched by operating the handle, the pressure supplied from the oil pump is reduced. Oil is in the pressure chambers 8 (one is not shown)
And the other pressure chamber is connected to the tank, and a pressure difference is generated between the two pressure chambers 8 to operate the piston 6 to generate a steering assist force.

[0013] The valve housing 32 of the power steering device
, A hydraulic reaction force control valve (steering force control valve) 50 is integrally provided. This hydraulic reaction force control valve 50
Is constituted by a spool 52 fitted in a valve hole 51 formed therein so as to move forward and backward, an electromagnetic solenoid 54 serving as an actuator for controlling the operation of the spool 52, and the like. The worm shaft 22 of the power steering device is slidably fitted with a reaction force plunger 56 that applies a steering reaction force between the stub shaft 26 and the worm shaft 22 of the power steering device. A power chamber 58 is provided, and the hydraulic pressure controlled by the hydraulic reaction force control valve 52 is introduced into the hydraulic reaction force chamber 58.

In the valve hole 51, three passage holes 60, 62 and 64 formed at intervals in the axial direction are opened. As described above (see FIG. 7), the outside of the passage holes 60, 62, 64
The opening 67 is provided on the joining surface 67. A passage hole 62 formed at the center of the figure is a supply passage hole connected to an annular groove 66 communicating with the inlet port 46 of the power steering device via a supply oil passage 68 in the valve housing 32. In addition, the pressure oil discharged from the oil pump and sent to the flow path switching valve 44 is divided and introduced into the hydraulic reaction force control valve 50. A passage hole 60 formed on the left side of the drawing is a passage hole connected to the hydraulic reaction force chamber 58 via a pressure passage 70 formed in the valve housing 32, and the hydraulic reaction force control valve 5
The hydraulic pressure controlled by 0 is sent to the hydraulic reaction force chamber 58 to act on the reaction force plunger 56. A passage hole 64 on the right side of the figure is a return passage hole connected via a return oil passage 74 to an annular space 72 communicating with the outlet port 48 of the power steering device. The return oil from the tank to the oil tank.

A wide annular groove 76 is formed in the inner peripheral surface of the valve hole 51 of the hydraulic reaction force control valve 50, and a passage hole connected to the hydraulic reaction force chamber 58 is formed in the annular groove 76. 60 is open. On the other hand, three annular grooves 78, 80, 82 are formed on the outer peripheral surface of the spool 52 slidably fitted in the valve hole 51, and the annular groove located at the center of the spool 52 is formed. 80 faces the wide annular groove 76 formed on the inner surface of the valve hole 51.
The supply passage hole 62 connected to the oil pump faces the right annular groove 82 formed on the outer peripheral surface of the spool 52. The annular groove 78 on the left side of the drawing is
2 radial through passage 84 and axial internal passage 8
Through 6, it communicates with a chamber (low pressure chamber) 88 formed on the right side of the figure. The inside of the low-pressure chamber 88 communicates with the return passage hole 64 connected to the oil tank via a space around a small diameter portion 90 formed at the right end of the spool 52.

An annular groove 80 at the center of the outer peripheral surface of the spool 52
And two land portions 92, 94 separating the annular grooves 78, 82 on both sides thereof, are formed with tapered surfaces, each having a gradually decreasing diameter toward the outside in the axial direction. The first and second variable throttles 9 are provided between the annular groove 76 on the side of the valve groove 51 and the edges of both side walls.
6,97 are constituted. As the spool 52 moves, the first and second variable throttles 96 and 97 form a flow path between the supply passage hole 62 and the passage hole 60 to the hydraulic reaction force chamber 58 and the hydraulic reaction force chamber 58. Passage hole 60 and return passage hole 6
4 is enlarged while the other is reduced. The spool 52 is constantly urged toward the electromagnetic solenoid 54 by a spring 98 disposed in a low-pressure chamber 88, and the electromagnetic solenoid 54 moves the spool 52 according to vehicle running conditions such as vehicle speed. Thus, the hydraulic pressure acting on the hydraulic reaction force chamber 58 is controlled by expanding and reducing the variable throttles 96 and 97.

When the vehicle is stopped or running at a low speed, the electromagnetic solenoid 54 moves the spool 52 against the spring 98 to the right in FIG. With the second variable aperture 9
Squeeze 7. At this time, the pressure oil discharged from the oil pump flows from the inlet port 46 of the power steering device to the annular groove 66 of the valve housing 32, the supply oil passage 68, and the supply passage hole 62 of the hydraulic reaction force control valve 50 to the spool 52. Flows into the annular groove 82 on the right side of FIG. 5, but since the second variable throttle 97 is narrowed or closed as described above, almost no pressure oil is sent to the hydraulic reaction force chamber 58, Steering reaction force is small, and light steering operation can be performed.

On the other hand, when the vehicle is running at a high speed, the force of the electromagnetic solenoid 54 pressing the spool 52 is removed, and the spool 52 is pushed back to the left in FIG. Then, contrary to the low speed, the first variable stop 96 is stopped down, and the second variable stop 97 is opened. Then, the pressure oil discharged from the oil pump is
From the inlet port 46 of the power steering device, through the supply passage hole 62, into the annular groove 82 on the right side of the spool 52, and further through the open second variable throttle 97, the hydraulic reaction force chamber 5
8 flows into the annular grooves 76 and 80 leading to the hydraulic reaction chamber 58.
Sent to At this time, since the first variable throttle 96 is in the throttled state, the reaction force acting on the hydraulic reaction force chamber 58 increases, a desired high steering reaction force is obtained, and the running stability at high speed is obtained. Can be secured.

The supply passage hole 62 formed in the hydraulic reaction force control valve 50 has a large diameter on the opening side, that is, on the joint surface 67 side with the valve housing 32 of the power steering device. A filter 99 is press-fitted therein. As shown in FIGS. 4 (a) and 4 (b), the filter 99 has an outer frame 10 to which the mesh 100 is attached.
2 has a spherical shape as a whole, and has a shape in which the top and bottom of this sphere are cut flat. A liquid passage 104 penetrating both flat surfaces 102a and 102b is formed.
Is installed. The outer diameter of the spherical frame 102 of the filter 99 is determined by the supply passage hole 62 of the hydraulic reaction force control valve 50.
Has a slightly larger diameter than the inner diameter of the large diameter portion 62a,
The filter 99 is press-fitted and fixed in the large-diameter portion (press-fitting hole) 62a (see FIG. 3). Since the frame 102 of the filter 99 is spherical as described above, it is not necessary to consider the inclination of the filter 99 when press-fitting the filter 99 into the supply passage hole 62 of the hydraulic reaction force control valve 50. Workability is good. Also, the supply passage hole 62
Since the small-diameter portion 62b on the inner side and the large-diameter press-fitting hole 62a on the outer side are coaxial, they can be processed at once by a stepped drill, and the number of processing steps can be reduced. Moreover, since the filter 99 is provided not on the valve housing 32 side of the power steering device but on the hydraulic reaction force control valve 50 side, dust can be easily cleaned.

Supply passage hole 62 of hydraulic reaction force control valve 50
The filter 99 is press-fitted in the
If the flow rate into the inside is large, the filter 99
If the difference between the direction of the internal passage 104 and the inclination of the passage hole 62 is large, the flow of the oil flowing from the oil pump may be affected, and turbulence may occur. In such a case, the internal passage formed in the frame of the filter may be shaped as shown in FIG. 5 or FIG.

That is, in FIG. 5, the internal liquid passage 204 formed in the frame 202 of the filter 299 is a tapered passage, and the large diameter side 204 of the tapered passage 204 is used.
a is press-fitted so as to face the inside of the passage hole 62. With this configuration, the flow of the pressure oil is smooth without being sharply bent, and does not have any adverse effect such as turbulence. FIG. 6 shows that an internal passage 304 having an inclination substantially corresponding to the inclination of the supply passage hole 62 is formed with respect to the axis 306 of the spherical frame 302, and the inclination direction of the supply passage hole 62 and the filter 399. The inclined direction of the internal passage 304 formed in the frame 302 is press-fitted in the same direction. In this embodiment, since the press-fit direction of the filter 399 is restricted, there is a problem that the assemblability is deteriorated. However, the flow of the pressure oil introduced into the hydraulic reaction force control valve 50 is smooth, and the turbulent flow There is no possibility that adverse effects such as the above will occur.

In the above embodiment, the power steering apparatus provided with the hydraulic reaction mechanism has been described, but the invention is not limited to the hydraulic reaction system. For example, JP-A-2-3069
No. 78 discloses a variable throttle valve that is controlled to open and close according to vehicle running conditions such as vehicle speed, and a steering angle-responsive variable throttle controlled by relative rotational displacement between input and output shafts. A power steering device of a type that controls a steering force by controlling a partial flow rate to a bypass passage connected to a return passage from a flow path switching valve to a tank by a variable throttle is described. The variable throttle valve (steering force control valve) used in the power steering device of the present invention can also be applied to a case where the variable throttle valve (steering force control valve) is integrally provided in the valve housing of the power steering device as in the above-described embodiment.

[0023]

As described above, according to the present invention, the steering force control valve for controlling the pressure or the flow rate is provided integrally with the valve housing of the power steering device, and the steering force control valve is provided with an oil pump. A passage hole in an inclined direction that communicates with a passage branched from a high-pressure oil passage that sends pressure oil to a passage switching valve from the oil passage, and a filter is press-fitted into an oil passage extending from the branch passage to the passage hole. In the power steering device, by forming the outer peripheral surface of the filter frame into a spherical shape and press-fitting the spherical frame into the inclined passage hole, a passage hole for press-fitting the filter is formed by one process. It is possible to reduce the number of processing steps and cost. Also, since the frame is spherical, it is not necessary to consider the inclination of the filter when press-fitting, and the workability is extremely excellent. Moreover, since the filter is press-fitted on the steering force control valve side, it is easy to clean the accumulated dust.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a power steering apparatus according to one embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a steering force control valve (hydraulic reaction force control valve) provided integrally with the power steering device.

FIG. 3 is a sectional view taken along the line III-III in FIG. 2;

4A is a plan view of a filter used in the power steering device, and FIG. 4B is a longitudinal sectional view thereof.

FIG. 5 is a diagram corresponding to FIG. 3, illustrating another example of a filter.

FIG. 6 is a diagram corresponding to FIG. 3, showing still another example of the filter.

FIG. 7 is a diagram showing a joint surface of a steering force control valve to a valve housing of a power steering device.

FIG. 8 is a cross-sectional view of a conventional steering force control valve.

FIG. 9 is a cross-sectional view showing another example of a conventional steering force control valve.

[Explanation of symbols]

 Reference Signs List 32 valve housing 44 flow path switching valve 50 steering force control valve (hydraulic reaction force control valve) 62 passage hole 68 branch passage 99 filter 102 filter frame

Claims (3)

[Claims] 1. A steering force control valve for controlling a pressure or a flow rate is provided integrally with a steering valve housing, and the steering force control valve branches from a high-pressure oil passage that sends pressure oil from an oil pump to a flow path switching valve. A power steering device having a passage hole in an inclined direction communicating with the passage, and a filter being press-fitted into an oil passage from the branch passage to the passage hole, wherein an outer peripheral surface of a frame of the filter is spherical. A power steering device wherein the spherical frame is press-fitted into the inclined passage hole. 2. The power steering apparatus according to claim 1, wherein the liquid passage penetrating through the inside of the frame of the filter has a tapered shape expanding toward the inside of the steering force control valve. 3. A liquid passage penetrating through the frame of the filter is formed so as to be inclined with respect to the axis of the frame, and the liquid passage is press-fitted into the passage hole so as to match the inclination direction of the passage hole. The power steering apparatus according to claim 1, wherein: