JP2582249Y2 - Hydraulic power steering device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic power steering apparatus provided with a two-stage throttle mechanism for returning oil to a tank.

[0002]

2. Description of the Related Art A control valve connected to a pump, a tank, and a hydraulic actuator is provided. The control valve throttles oil flowing from the pump to the tank at the time of steering and supplies hydraulic oil to the hydraulic actuator to increase steering assist force. Hydraulic power steering devices that generate this have been used conventionally.

[0003] In such a hydraulic power steering apparatus, since oil flowing from the pump to the tank is throttled by the control valve during steering, bubbles are generated in the oil due to a sudden change in pressure at the throttle, and the oil flow is reduced. It was a cause of sound generation.

Therefore, a mechanism is provided downstream of the throttle portion of the control valve to throttle the oil flowing out of the control valve into the tank at the time of steering, so that a back pressure is applied to the throttle portion of the control valve to prevent generation of bubbles. Do 2
A step-drawing mechanism has been proposed (JP-A-55-39883).
Reference).

[0005] As shown in FIG. 5 (1), the hydraulic control valve housing 102 is provided with a pressure oil supply hole 103 flowing from the pump to the control valve,
Return hole 1 for oil flowing from control valve to tank
04 and a communication hole 105 communicating the supply hole 103 and the return hole 104 are formed, and a throttle valve 106 is inserted into the communication hole 105. Thus, when the pressure of oil flowing through the supply hole 103 during steering increases due to steering resistance, the throttle valve 106 moves against the elastic force of the spring 108 to reduce the flow passage area of the return hole 104, and the control valve Since the oil flowing out to the tank is throttled, back pressure acts on the throttle portion of the control valve, thereby preventing generation of bubbles.

[0006]

In the conventional structure shown in FIG. 5A, the axis of the return hole 104 formed in the housing 102 is not on a straight line, and is located between the upstream portion 104a and the upstream portion 104a of the throttle valve 106. The axis was shifted from the downstream portion 104b.
If the axis is not on one straight line, the upstream portion 104a of the throttle valve 106 is drilled in the housing 102 from the right side in the figure, and the downstream portion 104b of the throttle valve 106 is located on the left side in the figure. It is necessary to make a hole in the housing 102 from above. However, since the right side of the housing 102 in the figure covers the valve member of the control valve and the like, in order to form a hole from the right side, the housing 102 is formed by two members 102a and 102b as illustrated. There is a problem that it is necessary to divide the structure, and the number of parts increases and the structure becomes complicated. Also, the number of steps for drilling the return hole 104 has increased.

As shown in FIG. 5B, when the return hole 104 has an axial center on one straight line, when the throttle valve 106 reduces the flow passage area of the return hole 104, the throttle valve 106 The upstream side 106a protrudes greatly inside the return hole 104,
The friction between the throttle valve 106 and the inner surface of the communication hole 105 increases due to the pressure of the oil flowing through the return hole 104, and the throttle valve 1
06 malfunction occurs.

Therefore, as shown in (3) of FIG. 5, an upstream portion 104a of the return hole 104 from the throttle valve 106 is formed in the housing 102 from the left side in the figure. Can be blocked by However, in this case, since the connection port 104c of the hose for connecting the return hole 104 and the tank is generally larger in diameter than the return hole 104, the housing 102 is used to prevent interference between the portion closed by the plug 107 and the connection port 104c. However, there is a problem that the size becomes large. In addition, the number of steps for forming the return hole 104 is large, and the plug 107 is also required, so that the cost increases.

An object of the present invention is to provide a hydraulic power steering apparatus which can solve the above-mentioned problems of the prior art.

[0010]

A feature of the present invention is to provide a control valve connected to a pump, a tank, and a hydraulic actuator. The control valve throttles oil flowing from the pump to the tank at the time of steering, and controls the hydraulic pressure. By supplying pressure oil to the actuator, a steering assist force is generated, and in the control valve housing, a supply hole for pressure oil flowing from the pump to the control valve, a return hole for oil flowing from the control valve to the tank, A communication hole communicating the supply hole and the return hole is formed, a throttle valve is inserted into the communication hole, and in the hydraulic power steering device that restricts oil flowing through the return hole at the time of steering by the throttle valve, the return hole is It has a straight axis, and the angle of intersection of the communication hole with this return hole is greater than that of the throttle valve in the tank. In the acute, the throttle valve, the
Throttle without projecting the upstream side of the throttle valve inside the return hole
In that it has a shape that allows the downstream side of the valve to protrude .

[0011]

According to the structure of the present invention, even if the return hole formed in the housing has a linear axis, the intersection angle of the communication hole with the return hole is closer to the tank than the throttle valve. since there is a sharp angle, without greatly protruding in the interior of the bore returns the upstream side of the throttle valve, or no be projected, to reduce the flow area of the return hole and flows out to the control valves or al tank Oil can be squeezed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

A rack and pinion type hydraulic power steering device 1 shown in FIG. 1 has an input shaft 2 connected to a steering wheel (not shown) of a vehicle, and a torsion bar 6 connected to the input shaft 2.
And an output shaft 3 connected thereto via the The torsion bar 6 is connected to the input shaft 2 via a pin 4 and connected to the output shaft 3 via a serration 5. The input shaft 2 is rotatably supported inside the valve housing 7 and the output shaft 3 via a bearing 8 and a bush 12. The output shaft 3 is rotatably supported inside the rack housing 9 via bearings 10 and 11.
A pinion 15 is formed on the output shaft 3, and a steering wheel (not shown) is connected to a rack 16 that meshes with the pinion 15. As a result, the rotation of the input shaft 2 due to the steering is transmitted to the pinion 15 via the torsion bar 6, and the rotation of the pinion 15 causes the rack 16 to move in the vehicle width direction. Done. A support yoke 40 for supporting the rack 16 is inserted into an insertion hole 9 a formed in the rack housing 9. Smoothness has been achieved.

A hydraulic cylinder 20 is provided as a hydraulic actuator for applying a steering assist force. The hydraulic cylinder 20 includes a cylinder tube configured by the rack housing 9 and a piston 21 integrated with the rack 16. A hydraulic control valve 30 is provided around the input shaft 2 to supply hydraulic oil to the oil chambers 22 and 23 partitioned by the piston 21 in accordance with the steering direction and the steering resistance.

The control valve 30 has a cylindrical valve member 31 inserted into the valve housing 7 so as to be relatively rotatable and surrounding the input shaft 2. The valve member 31 is connected to the output shaft 3 via a pin 32 so as to rotate together therewith. An inlet port 34 connected to a pump 33 and an outlet port 36 connected to a tank 35 are provided between the valve member 31 and the valve housing 17.
And a first port 37 connected to one oil chamber 22 of the hydraulic cylinder 20 and a second port 38 connected to the other oil chamber 23. Each port 34, 36, 3
Reference numerals 7 and 38 communicate with each other through an oil passage between the input shaft 2 and the valve member 31, and the opening of the oil passage is adjusted by the relative rotation between the input shaft 2 and the valve member 31 due to the torsion of the torsion bar 6. Is done.

That is, as shown in FIG.
Eight concave portions 50 are formed in the inner periphery of the inner surface at equal intervals in the circumferential direction. A convex portion 51 is formed on the outer periphery of the input shaft 2 so as to face the concave portion 50. The recess 50
Is connected to the first through a flow path 53 formed in the valve member 31.
The one communicating with the port 37 and the one communicating with the second port 38 via the flow path 54 formed in the valve member 31 are alternately arranged in the circumferential direction. The portion of the concave portion 50 in the circumferential direction includes a portion communicating with the inlet port 34 via a flow channel 55 formed in the valve member 31 and flow channels 52 a and 52 b formed in the input shaft 2 and a torsion bar. The portion communicating with the outlet port 36 between the inner and outer circumferences of the input shaft 2 and the input shaft 2 is alternately arranged in the circumferential direction.

FIG. 3 shows a state in which steering is not performed. The inlet port 34 and the outlet port 36 communicate with each other, the oil flowing from the pump 33 into the control valve 30 is returned to the tank 35, and the steering assist force is generated. do not do.

As shown in FIG. 4, when the torsion bar 6 is twisted by the steering resistance caused by steering to the left or right and the valve member 31 and the input shaft 2 rotate relative to each other, the relative position between the concave portion 50 and the convex portion 51 is increased. Changes. The recess 50
Due to the change in the relative position between the valve member 31 and the input shaft 2, the inlet port 34 and the first port 37
Of the oil passage A between the first port 37 and the outlet port 36, the oil passage B is narrowed, and the inlet port 3
The oil path C between the second port 38 and the second port 38 is narrowed, and the opening degree of the oil path D between the second port 38 and the outlet port 36 increases. Thereby, one oil chamber 22 of the hydraulic cylinder 20 is
Is supplied with pressure oil having a pressure corresponding to the steering direction and the steering resistance,
Further, the oil flows back from the other oil chamber 23 to the tank 35, and the steering assist force to the left or right of the vehicle acts on the rack 16 from the hydraulic cylinder 20. When steering to the other side, the valve member 3
1 and the input shaft 2 are relatively rotated in the opposite direction to the case where the steering is performed to the left or right, the opening degree of the oil passage C between the inlet port 34 and the second port 38 is increased, and the second port 38 and the outlet port 36, the oil path A between the inlet port 34 and the first port 37 is narrowed, and the opening degree of the oil path B between the first port 37 and the outlet port 36 is reduced. growing. Thereby, the steering assist force to the other side of the vehicle acts on the rack 16 from the hydraulic cylinder 20.

For example, as shown in FIG. 4, when steering to the left or right, the oil paths B and C of the oil flowing from the pump 33 to the tank 35 are throttled by the valve member 31, so that the oil pressure downstream of the throttle is reduced. When air bubbles are generated due to a sudden drop, the air bubbles cause flow noise. This is the same problem in the oil passages A and D throttled when the steering is performed to the other side. Therefore, there is provided a mechanism for preventing the generation of bubbles by applying a back pressure to the throttle portion by the valve member 31.

That is, as shown in FIGS. 1 and 2,
An inlet port 34 is connected to the valve housing 7 from the pump 33.
And a return hole 61 for the oil flowing out of the tank 35 from the outlet port 36.
A communication hole 62 that communicates with the return hole 61 is formed. The supply hole 60, the return hole 61, and the communication hole 62 each have an axis on one straight line. The outer end of the supply hole 60 is a connection port 60a of a hose for connection between the supply hole 60 and the pump 33, and the outer end of the return hole 61 is a connection port of a hose for connection between the return hole 61 and the tank 35. 61 a, and the outer end of the communication hole 62 is closed by a plug 64. A cylindrical throttle valve 63 is inserted into the communication hole 62. A compression coil spring 6 is provided between the throttle valve 63 and the plug 64.
The throttle valve 63 is provided by the elastic force of the spring 65.
Are urged toward the supply hole 60. The shaft 66 provided in the throttle valve 63 is inserted into the spring 65,
The displacement of the spring 65 is prevented. Thus, when the pressure of oil flowing through the supply hole 60 during steering increases due to steering resistance, the throttle valve 63 moves against the elastic force of the spring 65 to reduce the flow passage area of the return hole 61, and the control valve 30. The oil flowing out of the tank to the tank 35 is throttled, so that a back pressure acts on the throttle portion formed by the valve member 31 to prevent the generation of air bubbles.

On the tank 35 side of the throttle valve 63, the intersection angle θ of the communication hole 63 with the return hole 61 is an acute angle. Also, as shown in the figure, the throttle valve 6
3 is provided inside the return hole 61 on the upstream side 63 of the throttle valve 63.
a to protrude the downstream side of the throttle valve 63 without protruding
It has a shape that can be used. Thereby, the return hole 61
Has an axial center on one straight line, the throttle valve 63
Without protruding the upstream side 63a of the return hole 61 largely into the return hole 61, or without projecting it at all.
1 can reduce the flow passage area and reduce the oil flowing out from the control valve 30 to the tank 35. Therefore, the throttle valve 63 is not strongly pressed against the inner surface of the communication hole 62, and the malfunction of the throttle valve 63 is reduced. Can be prevented.

According to the above construction, the return hole 61 formed in the valve housing 7 is formed from one side (left side in FIG. 1) without unnecessarily dividing or enlarging the valve housing 7. Processing can be performed, and the number of parts and processing steps can be reduced.

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

[0024]

According to the hydraulic power steering apparatus of the present invention, when a two-stage throttle mechanism for preventing generation of bubbles by applying back pressure to the throttle portion of the control valve is provided.
Even if the return hole formed in the housing has a linear axis, malfunction of the throttle valve can be prevented, so that it is not necessary to divide or enlarge the housing to form the return hole. And the number of processing steps can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a front view of the valve housing according to the embodiment of the present invention;

FIG. 3 is a plan sectional view of the rotary valve according to the embodiment of the present invention;

FIG. 4 is a partial plan sectional view of the rotary valve according to the embodiment of the present invention;

FIG. 5 is a sectional view for explaining a conventional hydraulic power steering device.

[Explanation of symbols]

 7 Housing 20 Hydraulic actuator 30 Hydraulic control valve 33 Pump 35 Tank 60 Supply hole 61 Return hole 62 Communication hole 63 Throttle valve

Continuation of the front page (56) References JP-A-58-101869 (JP, A) JP-A-58-202165 (JP, A) JP-A-57-44569 (JP, A) JP-A-60-226369 (JP, A) , A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B62D 5/07 B62D 5/083

Claims (1)

(57) [Scope of request for utility model registration] 1. A control valve connected to a pump, a tank, and a hydraulic actuator. The control valve throttles oil flowing from the pump to the tank at the time of steering, and supplies hydraulic oil to the hydraulic actuator to provide a steering assist force. In the control valve housing, a supply hole for the pressure oil flowing into the control valve from the pump, a return hole for the oil flowing out of the control valve to the tank, and a communication hole communicating the supply hole and the return hole. Is formed, a throttle valve is inserted into the communication hole, and in the hydraulic power steering device that throttles oil flowing through the return hole at the time of steering by the throttle valve, the return hole has a linear axis, crossing angle of the communicating hole is than the throttle valve is an acute angle with the tank side, the throttle
The valve projects the upstream side of the throttle valve inside the return hole
Shape that allows the downstream side of the throttle valve to protrude without requiring
Hydraulic power steering system characterized in that it comprises a.