JPS6213904Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a power steering device that operates a flapper type control valve based on manual steering torque to control the supply and discharge of pressure fluid to a power cylinder. Another object of the present invention is to generate back pressure using the rotation of a flapper valve, thereby easily reducing throttling noise in a control valve.

Generally, in a power steering system, a back pressure throttle is provided on the discharge side of the control valve to limit the passage area according to the load pressure. It is well known that noise (throttling noise) is prevented, but in conventional power steering systems of this type, special back pressure control is used in the valve housing etc. to create back pressure throttling. It is necessary to provide a valve, which poses a problem of complicating the configuration.

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 is housed on the other side. A valve housing 13 is provided. 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, and the open end of the valve chamber is closed by a sealing member 21 that is fitted and fixed to one end of the main valve member 20. The member 21 is integrally molded on the inner ring of a bearing member 22 attached to the valve housing 13. And the valve chamber is the main valve member 20
The valve chambers are sealed and separated into two valve chambers 25 and 26 by a sealing separation member 23 fitted and fixed in the axially central portion of the valve chamber. As shown in FIG. 2, a pair of distribution nozzles 27 and 28 are opened on both side walls of one valve chamber 25 facing each other, and this valve chamber 25 is communicated with a supply port 29. Further, on both side walls of the other valve chamber 26, a third
As shown in the figure, a pair of outflow nozzles 31 and 32 are opened to face each other on one side in the diametrical direction, and
A pair of discharge nozzles 33 and 34 are opened to face each other on the other side in the diametrical direction, and this valve chamber 26 is connected to the discharge port 35 through the discharge nozzles 33 and 34 and through holes 51 and 52 formed in the sleeve valve portion 19. is communicated with. One valve chamber 25 has the distribution nozzle 2
A first flapper valve 37 for controlling opening and closing of the outflow nozzles 31 and 32 and discharge nozzles 33 and 34 is housed in the other valve chamber 26. These flapper valves 37 and 38 are configured such that the radius of rotation of the second flapper valve 38 is larger than the radius of rotation of the first flapper valve 37 in order to obtain an appropriate steering reaction force during steering. The first and second flapper valves 37, 38 are integrally formed with a steering shaft 39 rotatably supported by the bearing member 22, and the steering shaft 39 is connected to a steering handle via a joint (not shown) and a handle shaft. ing. The screw shaft 18, the first and second flapper valves 37, 38, and the steering shaft 3
A torsion bar 40 is inserted through the center of the torsion bar 9, 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 side 27 of the distribution nozzle and one side 31 of the outflow nozzle are communicated with each other by a communication passage 41, and a passage 42 (first
The right chamber 11b of the power cylinder 11 is communicated with the right chamber 11b of the power cylinder 11 through the right chamber 11b of the power cylinder 11. Further, the other distribution nozzle 28 and the other outlet nozzle 32 are communicated with each other by a communication passage 43, and power is supplied through a through hole 53 formed in the sleeve valve member 19, an annular groove 44, and a passage 45 (FIG. 1). It communicates with the left chamber 11a of the cylinder 11.

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 sent from the outlet 35 via the valve chamber 26 and the discharge nozzles 33 and 34 from the outflow nozzles 31 and 32. Because it is discharged, the left and right chambers 11a, 11 of the power cylinder 11
The pressure fluid in b does not increase in pressure and the steering wheel remains neutral. In this case, the fluid discharged from the outflow nozzles 31 and 32 into the valve chamber 26 is discharged from the discharge nozzles 33 and 34 on both sides to the discharge port 35, so that almost no discharge resistance occurs, and the valve chamber 26 is No pressure is generated.

However, when the steering handle is rotated, for example, to the right, the first and second flapper valves 37 and 38 cause one of the distribution nozzles 28 and the outflow nozzle 31 to be
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 right chamber of the cylinder 1.
1b and presses the piston 10 to the left,
The fluid in the cylinder left chamber 11a is discharged through the outflow nozzle 32.

At this time, the pressure fluid whose outflow is restricted from the outflow nozzle 31 flows out at high speed into the low-pressure valve chamber 26 through a small gap between the second flapper valve 38 and the valve wall, resulting in cavitation. However, in the present invention, one outflow nozzle 31 is closed by the rotation of the flapper valve 38, and at the same time, one of the discharge nozzles 34 is closed, so that no noise is generated from the valve chamber 26. The fluid discharged to the discharge port 35 is discharged from the discharge nozzle 3 on one side.
The discharge is only from the valve chamber 3, and the area of the discharge passage is halved, which causes discharge resistance, and this discharge resistance causes the discharge from the valve chamber 2.
A backpressure is generated within 6. This back pressure can prevent the generation of negative pressure when the pressurized fluid flows out at high speed through the small gap between the flapper valve 38 and the valve wall, thereby suppressing cavitation of the fluid and reducing unpleasant squeezing noise. .

As described above, the present invention provides a second valve that controls the outflow of the pressure fluid distributed and controlled by the first flapper valve.
The valve chamber housing the flapper valve is communicated with the discharge port via a pair of discharge nozzles, and the pair of discharge nozzles are opened and closed using the rotation of the flapper valve to control discharge resistance from the valve chamber. Therefore, when the flapper valve rotates, one of the discharge nozzles is closed and the discharge resistance increases, which generates back pressure in the valve chamber, which suppresses cavitation and reduces throttling noise. Moreover, it has the feature that this can be achieved with an extremely simple configuration.

Further, according to the present invention, when the flapper valve is in the neutral state, the discharge nozzles on both sides are opened and almost no discharge resistance is applied to the fluid discharged from the valve chamber to the discharge port, so there is no pressure loss and This also has the effect of not having a negative effect on the return of the steering wheel.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a sectional view of a power steering device, and FIGS. 2 and 3 are sectional views taken along lines - and - in FIG. 1. DESCRIPTION OF SYMBOLS 11...Power cylinder, 12...Flapper type control valve, 13...Valve housing, 20...Main valve member, 21...Sealing member, 23...Sealing separation member,
25, 26... Valve chamber, 27, 28... Distribution nozzle, 29... Supply port, 31, 32... Outflow nozzle, 33, 34... Discharge nozzle, 35... Discharge port, 37, 38... Flat flap Valve, 39... Steering shaft.

Claims (1)

[Scope of utility model registration request] In a power steering device that controls activation of a power cylinder operatively connected to steering wheels via a required connection means by a control valve operated based on manual steering torque, the power cylinder is operated in conjunction with the operation of the power cylinder. A main valve member to be rotated is rotatably fitted in a valve housing, and the main valve member has two valve chambers that are sealed and separated in the axial direction, and one valve chamber is provided with a valve that is supplied into the valve chamber. The first part controls the distribution of the pressure fluid.
A second flapper valve for controlling the outflow of distributed pressure fluid is housed in the other valve chamber, and these first and second flapper valves are connected to a steering shaft, and the other flapper valve is connected to the steering shaft. A pair of discharge nozzles, one of which is closed by rotation of the second flapper valve, are opened in the valve chamber, and the other valve chamber is communicated with the discharge port through the pair of discharge nozzles. A power steering device characterized by: