JPH018457Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a power steering device equipped with a flapper type control valve, and its purpose is to allow pressure to flow from an outflow nozzle between two restricted surfaces, the valve seat and the side wall. The objective is to prevent contractions from occurring when the fluid flows, thereby reducing squeezing noise.

In a power steering system equipped with a known flap control valve, the flow from the outflow nozzle is controlled by the relative rotation between the main valve member having an outflow nozzle opened in the side wall and the flapper valve equipped with a valve seat for opening and closing the outflow nozzle. The outflow amount of pressure fluid is restricted by a valve seat to generate the required pressure in the power cylinder.

In this type of flap type control valve, the pressure fluid flowing out from the outflow nozzle changes direction at right angles and flows between the two restricted surfaces of the valve seat and the side wall.
Contracted flow tends to occur near the inlet between the two surfaces of the valve seat and the side wall, and this contracted flow causes cavitation, which generates an unpleasant squeezing sound.

The present invention has been devised in view of the above-mentioned conventional problems, and embodiments thereof will be described below with reference to the drawings.

FIG. 1 shows a power steering device, in which a power cylinder 11 fitted with a piston 10 is provided on one side, and a flapper type control valve 12 for controlling the pressure fluid supplied to the power cylinder 11 on the other side.
A valve housing 13 is provided which houses the valve housing 13.
A rack 14 is carved on a portion of the circumference of the piston 10, and the rack 14 meshes with a sector gear 16 of a cross shaft 15 connected to a steering wheel via a link mechanism. A screw shaft 18 is screwed onto the piston 10 via a ball 17, and a main valve member 20 (second (see Figures 3 and 3) are integrally formed.

A valve chamber having side walls facing each other is formed in the main valve member 20 in the axial direction. It is sealed and separated into 25 and 26. A pair of distribution nozzles 27, 2 are provided on both side walls 25a of one valve chamber 25 as shown in FIG.
8 are opened to face each other, and this valve chamber 25 is communicated with a supply port 29. In addition, a pair of outflow nozzles 31 and 32 are opened to face each other on both side walls 26a of the other valve chamber 26, as shown in FIG. 3, and this valve chamber 26 is communicated with a discharge port 35. In one valve chamber 25, a first flapper valve 3 is provided with valve seats 33 on both sides for controlling opening and closing of the distribution nozzles 27 and 28.
7 is housed in the other valve chamber 26, and a second flapper valve 38 is housed in the other valve chamber 26, which has valve seats 34 on both sides for controlling the opening and closing of the outflow nozzles 31, 32. In order to obtain an appropriate steering reaction force, the radius of rotation of the second flapper valve 38 is configured to be larger than the radius of rotation of the first flapper valve 37. The first and second flapper valves 37, 38 are integrally formed with a steering shaft 39 rotatably supported on a bearing member, and this steering shaft 39 is connected to a steering handle via a joint (not shown) and a handle shaft. . the screw shaft 18, first and second
A torsion bar 40 is inserted through the center of the flapper valves 37, 38 and the steering shaft 39, and both ends of the torsion bar 40 are connected by pins to the screw shaft 18 and the steering shaft 39, respectively.

Said distribution nozzles 27, 28 and outflow nozzle 3
1 and 32, one of the distribution nozzles 27 and one of the outflow nozzles 31 communicate with an annular groove 43 formed in the sleeve valve member 19 through communication passages 41 and 42, and from this annular groove 43 through a passage 44. It is connected to the left chamber 11a of the power cylinder 11, and the other distribution nozzle 28 and the other outlet nozzle 32 are communicated with each other by communication passages 45 and 46, and the screw shaft 1
The right chamber 11b of the power cylinder 11 is connected to the right chamber 11b of the power cylinder 11 via a passage 47 bored at one end of the power cylinder 8.

Outflow nozzle 31 opened in the side wall 26a,
32, an arc-shaped chamfer 50 centered at point 0 is formed on the circumference as shown in FIG. It is tied at the surface.

Since the power steering system of the present invention is constructed as described above, when the steering wheel is in the neutral state, the first and second flapper valves 37 and 38 are closed as shown in FIGS. 2 and 3. is held in a neutral position within the valve chambers 25, 26, thereby allowing the supply port 29
The pressure fluid supplied to the valve chamber 25 is equally distributed to the distribution nozzles 27 and 28, and this distributed flow is discharged from the outlet 35 via the valve chamber 26 from the outflow nozzles 31 and 32, so that the power The pressure fluid in the left and right chambers 11a and 11b of the cylinder 11 does not increase in pressure, and the steering wheels maintain a neutral state.

However, when the steering handle is rotated, for example, to the left, the first and second flapper valves 37 and 38 cause one of the distribution nozzles 28 and the outflow nozzle 31
is closed and the other distribution nozzle 27 and outlet nozzle 32 are opened. As a result, the pressure fluid supplied to the valve chamber 25 is distributed only to the distribution nozzle 27 and sent under pressure to the outflow nozzle 31, but since the amount of outflow from this outflow nozzle 31 is restricted, the pressure increases, and this pressure increase The pressure fluid is in the cylinder left ventricle 1.
1a, the piston 10 presses to the right,
The fluid in the cylinder right chamber 11b is discharged through the outflow nozzle 32.

Here, the pressure fluid whose outflow from the outflow nozzle 31 is restricted by the valve seat 34 flows between the valve seat 34 and the side wall 2.
6a, the pressure fluid flows out at high speed into the low-pressure valve chamber 26, but in the conventional type, the pressure fluid changes direction at right angles from the outflow nozzle 31 and flows between the valve seat 34 and the side wall 26a. When flowing between two restricted surfaces, it tends to cause contracted flow, and this contracted flow causes cavitation.

However, in the present invention, by providing an arcuate chamfer 50 at the opening end of the outflow nozzle 31, the pressure fluid flows smoothly along the arcuate surface, and between the two surfaces of the valve seat 34 and the side wall 26a. Contracted flow does not occur in the vicinity of the inlet of the constricted flow, and therefore cavitation due to contracted flow is prevented and squeezing noise (shu sound) can be reduced.

The shape of the chamfer 50 to be applied to the openings of the outflow nozzles 31 and 32 may be formed by forming only a single circular arc surface as shown in FIG. A similar effect can be expected even if the shape is a combination of two circular arc surfaces at the center.

As described above, the present invention has a configuration in which the opening end of the outflow nozzle that is opened and closed by the valve seat is chamfered in an arcuate manner. Even when flowing between the two surfaces, the pressure fluid flows smoothly along the arcuate surface and does not cause contraction. Therefore, the occurrence of cavitation due to contracted flow can be prevented, and an unpleasant squeezing sound (shu sound) can be reduced, which is a practically beneficial effect.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a sectional view of the power steering device, FIGS. 2 and 3 are sectional views taken along the - line and - line in FIG.
The figure is a sectional view of a flapper type control valve showing the main part of the present invention, and FIG. 5 is a sectional view showing a modification of FIG. 4. DESCRIPTION OF SYMBOLS 11...Power cylinder, 12...Flapper type control valve, 20...Main valve member, 27, 28...Distribution nozzle, 31, 32...Outflow nozzle, 37, 38
... Flat valve, 50 ... Arc surface (chamfer).

Claims (1)

[Scope of utility model registration request] A power cylinder is controlled by a flapper type control valve comprising a main valve member having a pressure fluid outlet nozzle opened in a side wall, and a flapper valve rotatably housed in the main valve member and equipped with a valve seat for opening and closing the outlet nozzle. A power steering device for selectively supplying pressurized fluid to left and right chambers of a vehicle, wherein the opening end of the outflow nozzle is chamfered in an arc shape.