JPH0125741Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a flapper type servo valve device.

Generally, in a servo valve of a power steering device, for example, in a flapper type servo valve device, as the valve seat of the flapper valve approaches the jet port of the main valve member, the pressure difference between the supply side and the discharge side increases. When a large amount of pressure fluid flows out at high speed through a narrow throttle gap, a squeezing sound (swishing sound) is generated up to the narrow throttle gap.

Conventionally, in order to suppress such throttling noise, a recess is formed by machining on the side wall of the main valve member, and the pressure fluid that has passed through the throttling gap is recirculated between the inner peripheral edge of the recess and the valve seat. The annular gap formed in between reduces the flow velocity and suppresses the squeezing noise.

However, in such conventional devices, the side walls of the main valve member face each other at a relatively narrow distance necessary to accommodate the flapper valve, and a special cutter is required to machine the recess into the side wall. Alternatively, a processing machine must be used, and since the recessed portion requires precision, there is a drawback that manufacturing is time-consuming.

The present invention was devised in order to solve these conventional problems, and by manufacturing a control plate having a control hole separately from the main valve member and assembling this control plate to the side wall of the main valve member. , to easily and quickly manufacture a servo valve device.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a power steering device, in which a fluid pressure cylinder 1 into which a piston 2 is fitted is provided on one side, and a servo valve device 3 for controlling the pressure fluid supplied to the fluid pressure cylinder 1 is housed on the other side. Valve housing 10
is provided. A rack 4 is carved on a part of the circumference of the piston 2, and the rack 4 meshes with a sector gear 6 of an output shaft 5 connected to a steering wheel via a link mechanism. A screw shaft 9 is screwed into the piston 2 with a ball 8 interposed therebetween, and one end of this screw shaft 9 serves as a main valve member 12 having a sleeve valve member 11 fitted and fixed to the outer periphery of the valve housing. It is fitted in 10. A valve chamber having opposing side walls 12a and 12b (see FIG. 2) is formed through the main valve member 12 in the axial direction. This valve chamber is separated into two valve chambers 14 and 1 at both ends by a sealing separation member 13 fixed to the central portion of the main valve member 12.
5 are sealed and separated. The valve chambers 14 and 15 communicate with a supply port 16 and a discharge port 17, respectively, and a third valve chamber is provided on both side walls 12a and 12b of each valve chamber 14 and 15.
Dispensing ports 18, 19 facing each other as shown
And jet ports 56 and 57 are open, respectively.

One valve chamber 14 houses a first valve body 24 which is a flap valve having a diametrically protruding portion and valve seats 22 and 23 on both sides of the protruding portion. A second valve body 27 having a protrusion in the diametrical direction is also accommodated. This second valve body 2
7 is also a flapper valve with valve seats 25 and 26 on both sides of the protrusion. And this first valve body 24,
The second valve body 27 obtains an appropriate steering reaction force during steering, the radius of rotation of the first valve body 24 is smaller than that of the second valve body 27, and the first valve body 24 and the second valve body 27 are It is integrally formed and is further integrated with the steering shaft 28.

The steering shaft 28 projects outside the valve housing 10, and this projecting end and the threaded shaft 9 are connected to the first valve body 2.
4. The second valve body 27 and the steering shaft 28 are connected to each other by a torsion bar 29 passing through the center thereof. A steering shaft 28 protruding to the outside of the valve housing 10 is connected to a steering handle (not shown), and is adapted to be rotated from side to side by a steering person.

42 is a bearing that rotatably supports the main valve member 12 on the valve housing 10. Its outer ring 42a is fitted into the support member 41 fixed to the open end of the valve housing 10, and the inner ring 42b is integrally attached to the main valve member 12. It is fitted properly. In addition, the steering shaft 28 is connected to the inner wheel 4.
2b rotatably supported via rollers 43,
This inner ring 42b forms a bearing member that supports the steering shaft 28. On the other hand, the screw shaft 9 is rotatably supported by the valve housing 10 in the thrust direction via a roller 45, and a roller 44 is interposed between the screw shaft 9 and the inner end of the steering shaft 28.

A fluid passage connecting the servo valve device 3 configured as described above and the fluid pressure cylinder is configured as shown in the circuit diagram shown in FIG. 3. That is, the spout 56 is connected to the communication path 60.
The spout 57 is communicated with the distribution port 18 through a communication passage 61 .
Further, the communication passage 60 communicates with the cylinder left chamber 1a via a passage 62, and the communication passage 61 communicates with the cylinder right chamber 1b via a passage 63. Note that the supply port 16 communicating with one valve chamber 14 is connected to a pressure fluid supply source (pump) not shown, and the discharge port 17 communicating with the other valve chamber 15 collects the fluid ejected from the jet ports 56 and 57. and returned to the source.

The main part of the present invention is that in such a flapper type servo valve device, the side wall 12a of the main valve member 12,
This is because the control plate 65 is attached to 12b. That is, this control plate 65 has both ends bent into a U-shape as shown in FIG. 4, and control holes 67 with inner peripheries larger than the outer peripheries of the valve seats 25 and 26 are formed in the bent portions 66, respectively. This is the configuration. The control plate 65 is installed by being inserted between the side walls of the main valve member 12 facing each other as shown in FIG. It is fixed with an adhesive or the like at a position where it can enter into the interior of 67. In this installed state, an annular control chamber 68 is formed between the control hole 67 of the control plate 65 and the valve seat 26, and the outflow of pressure fluid from the spout 56 into the valve chamber 15 is suppressed. ing.

Next, the operation of the above configuration will be explained.
When the steering wheel is in the neutral state, the first valve body 2
4. The second valve body 27 is both located in the neutral state of the valve chambers 14 and 15, and the pressure fluid supplied into the valve chamber 14 from the supply port 16 flows into the distribution ports 18 and 19, and the jet port 56, 57 and flows out to the valve chamber 15 and the discharge port 17. In such a neutral state, the fluid pressures acting on the left and right cylinder chambers 1a and 1b are balanced,
The piston 2 does not operate and the steering wheel remains in a neutral state.

Now, when the steering wheel is rotated left and right, the road surface resistance transmitted from the wheels is acting on the screw shaft 9, so the torsion bar 29 is twisted and the steering shaft 28 is rotated.
rotates relative to the main valve member 12. As a result, the first valve body 24 and the second valve body 27 are tilted to the left and act to close one distribution port 19 and spout 56, and act to open the other distribution port 16 and spout 57. do. Therefore, the pressure fluid supplied into the valve chamber 14 is fed under pressure to the jet port 56 through the other distribution port 18, but the amount of pressure fluid flowing out from the jet port 56 is limited by the valve seat 26. Therefore, the distributed pressure fluid is introduced into the cylinder left chamber 1a through the communication passage 62, pushes the piston to the right, and deflects the steering wheel to the left. In this way, the small steering torque applied to the steering wheel by the steering person is assisted by the movement of the piston 2, making it possible to easily deflect the steering wheels.

In addition, pressure fluid acts on the valve seat 25 to generate a reaction force that attempts to return the steering shaft 28 in the opposite direction to the steering direction, thereby causing the first valve body 24 and the second
The steering person senses a steering reaction force that corresponds to the difference in the rotational moment of the valve body 27, that is, a steering feeling that corresponds to the deflection angle of the steered wheels.

By the way, as the valve seat 26 approaches the spout 56, the throttle gap 69 between the side wall 12a of the main valve member 12 and the valve seat 26 gradually narrows, and the pressure fluid spouted from the spout 56 flows through this gap 69. flows out at high speed. However, in the present invention, since the control chamber 68 is formed around the valve seat 26, the pressure fluid that has passed through the throttle gap 69 is suppressed from flowing out again in the control chamber 68, and as a result, back pressure is created in the control chamber 68. occurs. Due to this back pressure generation, the flow velocity of the pressure fluid passing through the throttle gap 69 is reduced,
Cavitation in the vicinity of the aperture gap 69 and accompanying aperture noise can be prevented. Also, the valve seat 25 is
7, the control plate 65 functions in the same manner as described above to prevent the generation of throttling noise.

In the above embodiment, the control plate 65 was manufactured by bending both ends of the plate into a U-shape, but the control plate 65 is not limited to this embodiment.
As shown in the figure, a control plate 70 may be used in which both ends of an arcuate plate are bent and control holes 72 are formed in the bent portions 71. This control plate 7
0, the bent portion 71 must be attached to the main valve member 1.
side walls 12 located on both sides of the axis line of 2;
a, 12b, and then tightened and fixed to the main valve member 12 with the screw 73.

As described above, according to the device of the present invention, the pressure fluid ejected from the spout is throttled by the throttling gap between the side wall of the main valve member and the valve seat, and then further compressed between the control hole of the control plate and the valve seat. Since the configuration is such that the flow rate of the pressure fluid passing through the throttle gap is reduced by controlling the control chamber formed in between, the flow rate of the pressure fluid passing through the throttle gap is reduced, and cavitation in the area around this gap and the accompanying This has the advantage that generation of squeezing noise can be effectively prevented.

In addition, the device of the present invention has a configuration in which the control plate with the control hole is manufactured as a separate member from the main valve member, and this control plate is attached to the main valve member, so the main valve member cannot be directly machined. It has the advantage of being extremely simple to manufacture compared to conventional methods.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a longitudinal sectional view of a power steering device equipped with the device of the present invention, FIG. 2 is an enlarged sectional view taken along the line - - in FIG. FIG. 4 is a perspective view showing the control plate and its mounting state; FIG. 5 is a perspective view showing another embodiment of the control plate. 12... Main valve member, 12a, 12b... Side wall,
27... Valve body (flat valve), 25, 26... Valve seat, 65, 70... Control plate, 67, 72...
...Control hole, 68...Control room, 69...Aperture clearance.

Claims (1)

[Scope of utility model registration request] A flapper type servo valve device that controls a throttle clearance that causes a pressure fluid to flow from the spout to the discharge side by moving the valve seat of the flapper valve toward and away from the side wall of a main valve member that has a spout opening that communicates with the supply side. A control plate having a control hole having a diameter larger than the outer circumferential edge of the valve seat is fixed to the side wall of the main valve member, and a control plate is provided between the control hole of the control plate and the valve seat from the spout to the discharge side. A flapper type servo valve device characterized by forming an annular control chamber for suppressing the outflow of pressure fluid.