JPH0143977Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a rotary valve for a power steering device.

Rotary valves used in power steering devices shift the position of each groove between the valve body and valve spool by using the torsion bar that causes torsion displacement when the handle is operated.
The pressure oil from the hydraulic pump is switched to apply hydraulic assist force to the steering device, allowing for easier steering operation.

In the conventional rotary valve, as shown in Fig. 1, pressure oil from the pump flows from import 1 to oil line 2.
The oil enters the annular groove 4 of the valve body 3 through the valve body 3, passes through the plurality of oil passages 5 of the valve body 3, passes through the valve spool portion 21 of the input shaft 19 and the plurality of axial grooves 7a, 8, and 7b of each of the valve bodies 3, and enters the imp. It passes through a plurality of return oil passages 9, 10 in the shaft 19, returns to the return port 11, and returns to a tank (not shown). When operating the handle, through the plurality of axial grooves 8,
The oil flows selectively into the annular groove 22 or 24 of the valve body 3 and flows through the respective oil passages 23 and 25 to an output cylinder (not shown).
And input shaft 19 and pinion 15
In order to control the relative movement of the integrated valve body 3 by the drive pin 20, a circumferential groove 26 is formed in the upper land part 30 of the valve spool part 21 of the input shaft 19, and a vibration damping member, usually The O-ring 27 is fitted into the circumferential groove 2 by the slot 12 provided in one of the plurality of axial grooves 7a.
Pressure oil is connected to the valve body 3 of the vibration damping member 27, so that the vibration damping effect according to pressure fluctuation is
Contact with the inner diameter portion 28 of the inner diameter portion 28 can be obtained even in response to pressure fluctuations. However, as vehicles have recently become smaller and lighter, the wall thickness of the valve body has become thinner, and as a result, the fitting clearance between the valve body and the valve spool changes in the axial direction with pressure fluctuations, making it difficult for the valve body and the valve spool to smoothly connect. A drawback has arisen in that relative movement is obstructed. Furthermore, if the fitting clearance is made large in consideration of the aforementioned reduction in the inner diameter, internal oil leaks at high temperatures, resulting in a delay in valve operation, and the handle becomes heavy.

In this invention, a cylindrical valve spool, which has a plurality of long grooves evenly distributed on its outer circumferential surface that communicate with the pump and the tank alternately, communicates with different cylinders alternately, and has the same number of long grooves as the above-mentioned long grooves. The valve body is relatively rotatably fitted into a cylindrical valve body that is equally spaced on the inner circumferential surface, and the valve body is fitted into the cylinder so as to be relatively rotatable, and as the communication area changes between the long grooves as a result of the relative rotation. In a rotary valve for a power steering device that controls hydraulic pressure, a circumferential groove is formed at both ends of the valve spool, and the circumferential groove communicates with the long groove communicating with the pump through at least one slot each. At least one of the circumferential grooves is fitted with a vibration damping member that is actuated by pressure oil from the pump, thereby equalizing dimensional changes in the radial direction of the inner surface of the valve body in the axial direction and reducing pressure fluctuations. Even if there is a problem, the fitting gap between the valve body and the valve spool always changes to the same extent over the entire axial length, thereby ensuring the minimum fitting gap and eliminating the drawbacks of the conventional valve spool.

The present invention will be described below based on Examples. Second
The figure shows one embodiment of the present invention, and FIG. 3 is a partially enlarged view thereof. A circumferential groove 26 similar to the conventional one is formed in the upper land portion 30 of the valve spool portion 21 of the input shaft 19, and a vibration damping member, an O-ring 27 in the embodiment, is fitted into the upper land portion 30, and a plurality of axial grooves 7a are formed.
A slot 12 in one of the grooves 26 communicates pressure oil with the circumferential groove 26. Furthermore, this circumferential groove 26
A circumferential groove 31 having a width comparable to that of the valve spool section 21 is formed in the lower land portion 32 of the valve spool portion 21, and a slot 13 provided in one of the plurality of axial grooves 7a allows pressure oil to flow into the circumferential groove 31. I am beginning to be guided.

Next, the effect will be explained.

Turn the handle to the right, input shaft 1
9 rotates to the right, and the pressure oil from the import 1 passes through the oil passage 2, the annular chamber 4, the plurality of oil passages 5, the plurality of axial grooves 7a, the annular chamber 22, and the oil passage 23, as shown in the figure. Oil is distributed to cylinders that are not available.

On the other hand, the pressure oil returned from the other cylinder passes through the port 25, the annular chamber 24, the plurality of axial grooves 8, 7b, and the oil passages 9, 10, and returns from the return port 11 to a tank (not shown). . At this time, the pressure oil supplied from the import 1 also acts on the vibration damping groove 26 through the axial slot 12 provided in the input shaft 19, and the pressure acting on the annular groove 22 of the valve body 3 is Therefore, a difference occurs in the load due to the applied pressure, and the load due to the difference acts on the valve body 3 in a direction to contract it inward. When the handle is turned to the left, the pressure is applied to the circumferential groove 31 by the axial slot 13 in the same manner (opposite to when the handle is turned to the right), and the pressure acting on the annular groove 24 of the valve body 3 is Therefore, a difference is generated in the load due to the applied pressure, and this difference acts in a direction to contract the valve body 3 inward. That is, the upper and lower portions of the valve body are contracted radially inward during left-right steering, but the widths of the two circumferential grooves are made to be the same so that the amount of reduction can be the same. put.

According to the present invention, a cylindrical valve spool in which a plurality of long grooves that alternately communicate with the pump and the tank are equally distributed on its outer circumferential surface is alternately communicated with different cylinders, and the same number of long grooves as the long grooves are relatively rotatably fitted into a cylindrical valve body that is equally spaced on the inner circumferential surface of the cylinder. In a rotary valve of a power steering device that controls oil pressure supplied to a power steering device, a circumferential groove is formed at both ends of the valve spool, and
The circumferential grooves communicate with the long grooves that communicate with the pump through at least one slot each, and a damping member that is actuated by pressure oil from the pump is fitted into at least one of the circumferential grooves. Because they are fitted together, the amount of contraction in the radial direction of the inner surface of the valve body can be made to be the same in the axial direction, and the minimum fitting clearance can be secured, so the relative movement between the valve body and valve spool is smooth, and the valve It can operate normally and prevent internal oil leaks at high temperatures.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view of a conventional device, FIG. 2 is a front sectional view of an embodiment of the present invention, and FIG. 3 is a partially enlarged view of FIG. 2.
FIG. 4 is a cross-sectional view of FIG. 3. 1... Import, 2... Oil path, 3... Valve body, 4... Annular groove, 5... Oil path, 7a, 7
b, 8... Axial groove, 9, 10... Return oil path, 11... Return port, 12, 13... Slot, 18... Torsion bar, 19... Input shaft, 21... Valve spool, 26
... Circumferential groove, 27 ... Damping elastic body, 31 ... Circumferential groove.

Claims (1)

[Claims for Utility Model Registration] A cylindrical valve spool, which has a plurality of long grooves equally distributed on its outer circumferential surface that alternately communicate with the pump and the tank, is connected alternately to different cylinders, and has the same number of long grooves as the long grooves. The valve body is relatively rotatably fitted into a cylindrical valve body in which long grooves are equally distributed on the inner circumferential surface of the valve body. In a rotary valve of a power steering device that controls oil pressure supplied to a cylinder, a circumferential groove is formed at both ends of the valve spool, and the circumferential groove is connected to the long groove communicating with the pump and at least one slot each. A rotary valve for a power steering device, characterized in that the rotary valve is in communication with each other and has a vibration damping member fitted into at least one of the circumferential grooves and is actuated by pressure oil from a pump. A rotary valve for a power steering device according to claim 1, wherein the circumferential grooves formed at both ends of the valve spool have the same width.