JPH0130294Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a pressure oil rotary valve device for a rack-and-pinion type power steering device, and its purpose is to allow pressure oil from the import of the valve housing to flow into the annular oil groove of the valve body. This is intended to prevent the generation of beeping noises due to turbulence in the pressure oil.

Figures 1 and 2 show the pressure oil rotary valve device of a conventional rack-and-pinion power steering device, and the import 1a of the valve housing 1.
The pressure oil flows into the annular oil groove 2a on the outer periphery of the valve body 2 fitted into the inner hole 1b of the valve housing 1, and further flows into the four oil passages 2b provided in the radial direction from the annular oil groove 2a. The oil flows into the return port 1c from the oil passage 3b through a plurality of axial oil passages 3a formed on the outer periphery of the valve spool portion 3 fitted into the inner hole 2c of the valve body 2, which rotates when the handle is operated, and the cylinder (not shown). When the handle shaft is rotated by a large amount, the rack 5 that meshes with the pinion 4 and slides thereon is pressurized by the oil pressure of the cylinder, making the handle operation easier.
The import 1a of the valve housing 1 and the annular oil groove 2a on the outer periphery of the valve body 2 are communicated with each other through a through hole 1d having a circular cross-section. Since the through hole 1d cannot be made larger than the predetermined diameter, the flow velocity of the pressure oil flowing through the through hole 1d becomes 8 m/sec or more, and when the pressure oil flows into the annular oil groove 2a, the flow is disturbed. A beeping sound is generated. This beeping sound occurs not only during valve operation but also in the neutral position, and in particular, the beeping sound is highest at a position where the oil passage 2b is rotated approximately 10 degrees from the position where the through hole 1d meets the oil passage 2b. In order to reduce this beeping sound, the through hole 1d can be made larger to reduce the flow velocity of the pressure oil, or the annular oil groove 2a can be made deeper. This goes against the requirement that parts become smaller with the trend towards weight reduction, and with the shift to front-wheel drive, smaller size and lighter weight, the steering system gets closer to the passenger compartment and this beeping sound is transmitted into the passenger compartment through the steering wheel column and is heard by the driver. It had the disadvantage of causing discomfort.

In this invention, the import of the valve housing and the annular oil groove on the outer periphery of the valve body are made into a through hole with a flat cross section along the annular oil groove, compared to the conventional through hole with a circular cross section of the same size valve housing. The cross-sectional area is increased, the flow velocity of the pressure oil is reduced, and the pressure oil is moved in the tangential direction of the annular oil groove to reduce the beeping sound.

3 and 4 show an embodiment of the present invention, in which the import 11a of the valve housing 11 and the annular oil groove 12a on the outer periphery of the valve body 12 are connected to the annular oil groove 12a.
They communicate through a through hole 11d that has a flat cross section along line a.

According to the present invention, even if a large number of packings are provided on the outer periphery of the valve housing, a flat through hole is formed between the packings along the annular oil groove, so that the cross-sectional area can be kept the same size. It can be made sufficiently larger than the circular cross-sectional through hole in the valve housing, the flow velocity of pressure oil can be kept below 3 m/sec, and the pressure oil from the through hole can be transferred in the tangential direction of the annular oil groove. Direct impact on the radial oil path formed in the annular oil groove was minimized, and the beep sound was reduced by approximately 25 to 30 dB.

[Brief explanation of the drawing]

Fig. 1 is a front sectional view of the conventional device, Fig. 2 is a plane sectional view taken along line A-A in Fig. 1, Fig. 3 is a plane sectional view equivalent to Fig. 2 of an embodiment of the present invention, and Fig. 4 is a plane sectional view taken along the line AA in Fig. 1. It is a BB side view of FIG. 11...Housing, 11a...Import, 11
d...Through hole, 12...Valve body, 12a...Annular oil groove.

Claims (1)

[Scope of utility model registration request] Pressure oil from the import of the valve housing flows into the annular oil groove on the outer periphery of the valve body fitted into the inner hole of the valve housing, and the pressure oil is released by relative displacement with the valve spool fitted into the inner hole of the valve body, which rotates when the handle is operated. In a device configured to selectively supply oil to cylinders, the import valve housing and the annular oil groove on the outer periphery of the valve body communicate with each other through a through hole having a flat cross section along the annular oil groove. Pressure oil rotary valve device for and pinion type power steering device.