JPS585669Y2 - Servo valve device for power steering device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a servo valve device for controlling a fluid pressure motor of a power steering system. A damping plate is interposed in the axial gap formed between the flapper valve and the flapper valve to stabilize the valve characteristics of the flapper valve and improve the steering feeling.

In general, a power steering device equipped with a servo valve device consisting of a flapper valve mechanism has the feature that the steered wheels can be quickly and accurately deflected to follow even a minute rotational displacement of the flapper valve mechanism.

However, since the sensitivity of the flapper valve mechanism is extremely good, the rise in fluid pressure in the fluid pressure circuit due to the operation of the flapper valve mechanism is extremely steep, which causes vibrations in the flapper valve mechanism, causing the servo valve mechanism to This has the disadvantage that the fluid control characteristics become unstable and the operator easily senses unpleasant vibrations.

In view of these conventional drawbacks, the present invention has been developed by interposing a damping plate in the axial gap formed between the inner ring of the angular contact type ball bearing that supports the steering shaft and the flapper valve. This is characterized in that the flapper valve is pressed by fluid pressure to obtain a friction damping effect.

Embodiments of the present invention will be described below with reference to the drawings.

What is shown in FIG. 1 is a power steering device, in which a fluid pressure cylinder 1 into which a piston 2 is inserted is provided on one side, and a servo valve device on the other side controls the pressure fluid supplied to the fluid pressure cylinder 1. A valve housing 10 containing a valve housing 3 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 ring mechanism.

A screw shaft 9 is screwed into the piston 2 with a ball 8 interposed therebetween, and one end of the screw shaft 9 has a sleeve valve member 1 attached to the outer periphery.
1 serves as a main valve member 12 which is fitted and fixed into the valve housing 10.

A valve chamber having opposing side walls is formed passing through the main valve member 12 in the axial direction, and this valve chamber is formed by a sealing member 13 fixed to the central portion of the main valve member 12, as shown in FIG. It is sealed and separated into two valve chambers 14 and 15 at both ends.

The valve chambers 14, 15 communicate with a supply port 16 and a discharge port 17, respectively, and distribution ports 18, 19 and jet injection ports are provided on both side walls of each valve chamber 14, 15, facing each other, as shown in FIGS. 2 and 3. Outlets 20,21 are each open.

Further, one valve chamber 14 has a diametrically protruding portion, and a first flapper valve 24 having valve seats 22 and 23 on both sides of the protruding portion is housed, and the other valve chamber 15 has a diametrically protruding portion. A second flapper valve 27 having a protrusion and having valve seats 25 and 26 only on one of the protrusions is accommodated.

So the first thing. The twenty-seventh flapper valves 24, 27 are configured such that the rotation radius of the first flapper valve 24 is smaller than that of the second flapper valve 27 in order to obtain an appropriate steering reaction force during steering.

Also number 1. The second flapper valves 24 and 27 are integrally formed, and a steering shaft 28 is integrally provided and protrudes to the outside of the valve housing 10.

The screw shaft 9, the first. A single torsion bar 29 is inserted through the center of the second flapper valve 24.27 and the steering shaft 28, and is connected to the screw shaft 9 and the steering shaft 28 by pins 30.31, respectively.

The end of the steering shaft 28 is connected to a steering handle via a joint and a handle shaft (not shown), and is configured to be rotated by the operator.

Reference numeral 42 denotes an angular contact type pole bear tongue which rotatably supports the main valve member 12 on the valve housing 10, the outer ring 42a of which is fitted into the support member 41 screwed onto the open end of the valve housing 10, and the inner ring 42a. 42 b is the main valve member 1
2, and this inner ring 42 b
A steering shaft 28 is rotatably supported via rollers 44 .

A damping plate 43 is interposed in the axial gap formed between the inner ring 42b and the second flapper valve 27.

The vibration damping plate 43 is made of a resin having excellent heat resistance and strength (for example, polyacetal resin, and its homopolymer is commercially available under the trade name Teurlin (registered trademark)).

), and when loaded with fluid pressure, the integral first . The second 7-lap valve 24.27 is pressed against the damping plate 43 and the first 7-lap valve 24.27 is pressed against the damping plate 43. The second flapper valve 24 and 27 have a damping effect that damps vibrations caused by the valve.

The fluid passage connecting the servo valve device 3 configured as described above and the fluid pressure cylinder 1 is as follows.

As shown in FIG. 3, a pair of arcuate grooves 32 and 33 are separately carved on the outer periphery of the main valve member 12 that is tightly fitted to the sleeve valve member 11 and communicate with the jet ports 20 and 21, respectively. The arc grooves 32 and 33 are connected to the distribution port 18 through flow passages 34 and 35 carved on the outer periphery of the main valve member 12.
19 and are connected to each other.

Further, an annular groove 36 is formed on the outer periphery of the sleeve valve member 11, and this annular groove 36 communicates with the one arcuate groove 32 and the distribution port 18 via flow passages 37 and 38.

The annular groove 36 communicates with the cylinder left chamber 1a via a passage 39 carved in the valve housing 10 and the hydraulic cylinder 1.

The other distribution port 19 communicates with a passage 40 bored at one end of the screw shaft 9, and this passage 40 communicates with the cylinder right chamber 1b.

The supply port 16 is connected to a flash pressure fluid supply source and supplies pressure fluid to one valve chamber 14 and the other valve chamber 15.
An outlet 17 in communication with the outlet 17 is adapted to collect fluid ejected from the outlet 20.21 to the source.

Next, the operation of the above configuration will be explained.

When the steering wheel is in the neutral state, the first. The second flapper valves 24, 27 are both located in the neutral state of the valve chambers 14, 15, so that the pressure fluid supplied into the valve chamber 14 from the supply port 16 flows into the distribution port 18, 19, and the jet port 20 .21 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 wheels maintain a neutral state.

Now, when the steering wheel is rotated to the right, road resistance is acting on the screw shaft 9, so the torsion bar 29 is twisted and the steering shaft 28 is rotated relative to the main valve member 12. Ru.

This leads to the first. The second flapper valve 24,27 is tilted to the right and acts to close one distribution port 18 and spout 21 and to open the other distribution port 19 and spout 20.

As a result, the pressure fluid supplied into the valve chamber 14 is forced to be sent to the spout 21 through the other distribution port 19, but the valve seat 26
Since the amount of pressure fluid flowing out from the spout 21 is limited by
Press to the left to deflect the steering wheels to the right.

In this way, the small steering torque applied to the steering wheel by the operator is assisted by the movement of the piston 2, making it possible to easily deflect the steering wheels.

Further, pressure fluid acts on the valve seat 26 to generate a steering reaction force that attempts to return the steering shaft 28 in the opposite direction to the steering direction, thereby causing the first. The driver can sense a steering reaction force corresponding to the difference in the rotational moments of the second flapper valves 24 and 27, that is, a steering sensation corresponding to the deflection angle of the steered wheels.

By the way, in the flapper valve mechanism as described above, the first
．． Even a slight rotational displacement of the second flapper valve 24, 27 causes the fluid pressure to rise very steeply, and this characteristic becomes even more pronounced when the steering handle is rapidly rotated.

Therefore, when the valve is operated, the first. Second flapper valve 24
．． 27, vibration was likely to occur.

At this time, in the present invention, a damping plate 43 is provided between the second flapper valve 27 and the inner ring 42b of the bearing 42.
is interposed, so when fluid pressure is generated as the steering handle rotates, this fluid pressure acts on the left end face of the first flapper valve 24 and presses it to the right, causing the torsion bar 29 to The second flapper valve 27 is pressed against the vibration damping plate 43 due to the slight extension in the axial direction, thereby causing the first flapper valve 27 to be pressed against the main valve member 12. Second flapper valve 24.2
7 relative displacement resistance force is applied, and the first. Vibration of the second flapper valve 24,27 is prevented.

Also, when the steering wheel is turned to the left, contrary to the above, the first. The second flapper valve 24.27 is pivoted to the left and the other distribution opening 19 and spout 20 are closed by the valve seat 23.25.

Therefore, the pressure fluid that is trying to flow out from the spout 20 is at the valve seat 2.
Bleed-off is controlled by 5, and the piston 2 is introduced into the cylinder left chamber 1a from one distribution port 18 through the circular arc groove 32, the flow passages 34, 37, 38, the annular groove 36, and the passage 39, and moves the piston 2 to the right. Press to deflect the steering wheels to the left.

In this case as well, the torsion bar 29 is slightly extended by the fluid pressure. The second flapper valve 24 , 27 is pressed against the divider plate 43 and the first flapper valve 24 . Since the frictional resistance of the second flapper valves 24 and 27 increases, the first flapper valve increases. Vibration of the second flapper valve 24,27 is prevented.

As described above, in the present invention, a main valve member is rotatably fitted into a valve housing, the main valve member houses first and second flapper valves for distributing and controlling pressure fluid, and these flapper valves An inner ring of an angular contact type ball bearing supporting a steering shaft integrally protruding from the main valve member is fitted into the main valve member, and the above-mentioned Since the configuration includes a vibration damping plate that is pressed in accordance with the fluid thrust acting on the first flapper valve, the vibration of the flapper valve is suppressed with an extremely simple configuration, and the friction of the flapper valve against the main valve member is Since the resistance is increased in accordance with the fluid thrust acting on the flapper valve, the vibration of the flapper valve is stably and effectively suppressed, the valve characteristics are stabilized, and an extremely good steering feeling can be obtained.

Moreover, according to the present invention, since the steering shaft is supported by an angular contact type ball bearing, twisting does not occur when the steering shaft rotates, contributing to further stabilization of the valve characteristics of the flapper valve. Effects can also be played.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of a power steering device showing an embodiment of the present invention, Fig. 2 is a cross-sectional view taken along the line ■■-■I in Fig. 1, and Fig. 3 is a cross-sectional view taken along III-III in Fig. 1. 4 is a sectional view taken along the line ■■-■■ in FIG. 1. 1...Fluid pressure cylinder (fluid pressure motor), 10
... Valve housing, 12 ... Main valve member, 24 ... First flapper valve, 27 ...
・Second 7 Ratsupa valve, 28...Steering shaft, 29・
...Torsion bar, 42b...Inner ring of angular contact ball bearing, 43...
...damping plate.

Claims (1)

[Scope of utility model registration request] In a servo valve device of a power steering device that controls activation of a fluid pressure motor operatively connected to a steering wheel via a required connection means by manual steering force, the main motor rotates in conjunction with the operation of the fluid pressure motor. A valve member is rotatably fitted into the valve housing, and the main valve member has a first valve chamber connected to the pressure fluid supply port and a second valve chamber connected to the discharge port sealed and separated in the axial direction. a first flapper valve for controlling distribution of pressure fluid and a second flapper valve for controlling outflow of pressure fluid are rotatably housed in the first and second valve chambers, respectively;
A steering shaft connected to an output shaft connected to the fluid pressure motor via a torsion bar is integrally provided on the first and second flapper valves, and a support member is screwed onto one end of the valve housing. an outer ring of an angular contact type ball bearing is fitted to the support member, an inner ring of the ball bearing is fitted to one end of the main valve member and is rotatably supported by the inner ring on the steering shaft; A damping plate is interposed in the axial clearance formed between the inner ring of the pole bearing and the second flapper valve, and the damping plate is pressed in response to the fluid thrust acting on the first flapper valve. A servo valve device for a power steering device.