JPS6143657Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vibration isolation mechanism for a hydraulic switching valve in a power steering system for a vehicle such as an automobile.

Generally, a power steering device is used to assist in transmitting steering force from a steering wheel of a vehicle to tires. In such a power steering device, in order to assist in transmitting steering force using hydraulic pressure,
A spool valve that is movable in the axial direction is provided coaxially with the input shaft that receives the steering force from the handlebar, and the hydraulic pressure is switched by moving the spool valve in the axial direction according to the rotational direction of the input shaft. However, since such a spool valve requires a clearance that allows it to move in the axial direction, this clearance may cause the spool valve to vibrate during operation, causing abnormal noise, or causing the spool valve to move. There is a problem in that the vibration of the valve causes the handle to vibrate.

Therefore, conventional vibration isolation mechanisms for spool valves include providing orifices on both sides of the spool valve or using springs to achieve vibration isolation. However, such a conventional vibration isolation mechanism has the disadvantage that it is mechanically quite complex and processing for vibration isolation is extremely difficult.

The present invention has been developed to eliminate the drawbacks of the prior art, and uses a simple vibration-proofing structure to prevent the vibration of the spool valve that constitutes the hydraulic switching valve, the generation of unpleasant noises, and the slight vibration of the handle. It is an object of the present invention to provide a vibration isolation mechanism for a hydraulic switching valve in a power steering device that can prevent vibrations from occurring.

In order to achieve this purpose, the vibration isolation mechanism of the hydraulic switching valve in the power steering device according to the present invention has an input shaft and an output shaft that are rotatably mounted on a common axis within the valve housing, and are equipped with a torsion bar. A spool valve is coaxially arranged around the input shaft and is movable in the axial direction as the input shaft rotates. A pair of annular grooves are formed on the inner wall surface of the spool valve at a portion substantially facing the port, and a pair of annular grooves facing the port are formed in the middle, and an annular sealing material that comes into contact with the inner wall surface of the spool valve is loosely fitted into each annular groove. , each sealing material is brought into pressure contact with the axially outer wall surface of each annular groove and the inner wall surface of the spool valve by hydraulic pressure from the port, thereby creating a space between the inner wall surface of the spool valve and a member that moves relative to the spool valve. It is characterized in that a sealed space is formed inside.

The present invention will be further explained below with reference to embodiments shown in the drawings.

FIG. 1 is a sectional view showing an embodiment of a power steering device incorporating a vibration isolation mechanism according to the present invention. 1st
In the figure, an input shaft 2 is inserted into a valve housing 1 and receives a steering force from a handle from its outer periphery. This input shaft 2 is connected via a torsion bar 5 to an output shaft 4 inserted into a rack housing 3, and this output shaft 4 is configured to mesh with a rack bar 3A at a pinion portion on its outer periphery. That is, the input shaft 2 and the torsion bar 5 are connected by a pin 6, while the torsion bar 5 and the output shaft 4 are connected by a pin 7. Further, needle bearings 8A and 8B are provided at two locations in the axial direction on the outer circumferential side of the input shaft 2 for rotation of the input shaft 2, and a ball bearing 9 is provided on the outer circumferential portion of the output shaft 4 on the input shaft 2 side. is provided.

An output shaft 4 of the input shaft 2 is disposed between the outer circumferential side of the input shaft 2 and the inner circumferential side of the valve housing 1.
Spiral ball groove 1 formed near the side end
A spool valve 11 is provided which is transmission coupled to the spool valve 11 as will be explained below. Spool valve 1
1 has a pressure port 12 on its upper end side in the axial direction (FIG. 1) that receives the supply of hydraulic oil from a hydraulic pump, and the ball groove 10 is provided on the opposite side in the diametrical direction below this pressure port 12. A ball 15 that engages with is held in the ball holding hole 13, and this ball 15 is held from the outer peripheral side by a ball retainer 16. Furthermore, spool valve 1
A stopper groove 14 is formed in the end of the output shaft 4 on the output shaft 4 side, and a pin 1 extending in the radial direction from near the end of the output shaft 4 on the input shaft 2 side is formed in the stopper groove 14.
7 is engaged. This stopper groove 14 and pin 1
7, the spool valve 11 is restricted from rotating with respect to the output shaft 4.

Inside the pressure port 12 of the spool valve 11, annular grooves 18 and 19 as shown in FIG. Annular groove 1
Each of 8 and 19 is fitted with a seal ring 20 and 21 made of a friction material. Together with the inner peripheral surface of the spool valve 11 and a portion of the outer peripheral surface of the input shaft 2, these two seal rings 20 and 21 form an annular sealed space 22 that can communicate with a hydraulic pressure source through the pressure port 12. There is.

Further, the valve housing 1 is formed with a return port 23 for returning hydraulic pressure to the reservoir, a right cylinder port 24 communicating with the right cylinder chamber, and a left cylinder port 25 communicating with the left cylinder chamber.

In this embodiment configured as described above, the input shaft 2 that receives the steering force from the handle rotates, so that the steering force is transmitted to the spool valve 11 via the ball 15.
Since the ball 1 cannot rotate due to the engagement between the pin 17 of the output shaft 4 and the stopper groove 14,
5 slides in the axial direction within the ball groove 10, the spool valve 11 moves in either direction in the axial direction depending on the direction of rotation of the input shaft 2, thereby switching the hydraulic pressure.

Next, the vibration damping effect of the spool valve 11 in this embodiment will be explained. When hydraulic oil is supplied from a hydraulic pump (not shown) into the annular sealed space 22 through the pressure port 12, the pressure of the hydraulic oil causes the seal rings 20 and 21 to move between the annular grooves 18 and 1.
The spool valve 11 is pressed against the axially outer wall surface of the input shaft 2 due to frictional contact between each seal ring 20, 21 and the inner wall surface of the spool valve 11 and the axially outer wall surface of the annular grooves 18, 19 of the input shaft 2. Vibration is prevented. Therefore, it is possible to prevent abnormal noises caused by vibrations of the spool valve 11, and also to prevent slight vibrations of the steering wheel.

In this case, in this embodiment, since the seal rings 20 and 21 are not pressed against the groove surface in the radial direction, there is no fear that the return of the handle will be impaired by both seal rings 20 and 21, and furthermore, in this embodiment Since the annular grooves 18 and 19 are formed on the outer peripheral surface of the input shaft 2, machining is much easier than in the case where the annular grooves are formed on the inner peripheral surface.

Note that it is also possible to provide a distance piece having a hydraulic communication hole between both seal rings 20 and 21.

Furthermore, the material of the seal rings 20 and 21 is such that it generates a friction force that can prevent vibration of the spool valve 11 due to the load when both the seal rings 20 and 21 are deformed and the friction coefficient of the seal rings 20 and 21. Any material may be used as long as it can be used. For example, an O-ring-shaped fluororesin ring may be used.

As explained above, according to the present invention, the return of the handle does not deteriorate due to the sealing material.
It is possible to prevent the spool valve constituting the hydraulic switching valve of the power steering device from vibrating during steering, etc., producing unpleasant noises or causing slight vibrations in the steering wheel.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing an embodiment of a power steering device incorporating a vibration isolation mechanism according to the present invention, and FIG. 2 is an enlarged partial sectional view of section A in FIG. 1...Valve housing, 2...Input shaft, 4...
...Output shaft, 5...Torsion bar, 11...Spool valve, 12...Pressure port, 18, 19...
...Annular groove, 20, 21...Seal ring, 22...
...Annular sealed space.

Claims (1)

[Scope of utility model registration request] The input shaft and output shaft, which are rotatably mounted on a common axis within the valve housing, are connected via a torsion bar, and a shaft moves around the input shaft in the axial direction as the input shaft rotates. A flexible spool valve is disposed coaxially, and a pair of annular grooves are formed in a portion of the outer peripheral surface of the input shaft that substantially opposes a port on the inner wall surface of the spool valve that communicates with the hydraulic pressure supply source, and facing the port with the port in the middle. is formed, and an annular sealing material that comes into contact with the inner wall surface of the spool valve is loosely fitted into each annular groove, and the hydraulic pressure from the port causes each sealing material to come into contact with the axially outer wall surface of each annular groove and the spool valve. A vibration isolating mechanism for a hydraulic switching valve in a power steering device, wherein a sealed space is formed between an inner wall surface of the spool valve and a member that moves relative to the spool valve in pressure contact with the inner wall surface of the spool valve.