JPS6039328Y2 - Vibration damping device in power steering system - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a vibration damping device in a power steering device that uses the sliding friction of resin to prevent vibration of a valve member. To reliably prevent vibrations occurring when pressurized fluid is at high pressure without impairing the feeling and bundle return at low pressure.

A power rudder in which the flapper valve housed in the valve member is coated with synthetic resin, and this synthetic resin is pressed against the inner surface of the valve member by the initial set load from the spring and the fluid pressure generated by steering to prevent vibration of the flapper valve. The steering device is known, for example, as shown in Japanese Utility Model Application Publication No. 54-46433, and is useful for improving the steering feeling by preventing such vibration.

However, in this type of power steering system, the sliding friction resistance of synthetic resin is necessary in a certain pressure range where vibration occurs, and in the lower pressure range, the sliding friction is necessary to improve the feeling and bundle return. It is preferable that the resistance be as small as possible, and it is difficult to satisfy both of these requirements in terms of design with the above-mentioned known structure.

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 provided on the other side. Stowed valve housing 1
3 is provided.

A rack 14 is carved on a part of the circumference of the piston 10, and the rack 14 meshes with a sector gear 16 on 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 (Fig. 3) are fixed.

The main valve member 20 is formed with a valve chamber having side walls facing each other passing through the main valve member 20 in the axial direction. , 26 are sealed and separated.

On both side walls of each valve chamber 25, 26 are distribution nozzles 27, 28 and a jet nozzle 29, as shown in FIGS. 2 and 3.
30 are opened, and these valve chambers 25 and 26 are communicated with a supply port 31 and a discharge port 32, respectively.

One valve chamber 25 accommodates a first flapper valve 35 that controls opening and closing of the distribution nozzle 27.28, and the other valve chamber 26 houses a second flapper valve that controls opening and closing of the jet nozzle 29.30. 38 are housed, and these flapper valves 35
．． The rotation radius of the second flapper valve 38 is larger than that of the first flapper valve 35 in order to obtain an appropriate steering reaction force during steering.

The first and second flapper valves 35, 38 are integrally formed with a steering shaft 39 rotatably supported on the valve housing 13,
This steering shaft 39 is connected to a steering handle via a flash joint and a handle shaft.

Said screw shaft 18, first and second flapper valves 35.3
8 and the center of the steering shaft 39, a torsion bar 40 is inserted, and both ends of this torsion bar 40 are connected to the screw shaft 1.
8 and a steering shaft 39, respectively.

Next, a fluid passage connecting the flapper type control valve 12 and the power cylinder 11 will be explained.

As shown in FIG. 3, a pair of arcuate grooves 51 and 52 are separately carved on the outer periphery of the main valve member 20 fitted into the sleeve valve member 19, each communicating with the jet nozzle 29 and 30. The arcuate grooves 51 and 52 communicate with the distribution nozzles 28 and 27 via flow passages 53 and 54 carved on the outer periphery of the main valve member 20, respectively.

Further, an annular groove 55 is formed on the outer periphery of the sleeve valve member 19, and this annular groove 55 communicates with the one arcuate groove 51 and the distribution nozzle 28 via a flash flow path.

The annular groove 55 is connected to the cylinder left chamber 11a through a passage 58 carved in the valve housing 13 and the power cylinder 11.
is communicated with.

The other arcuate groove 52 and distribution nozzle 27 are connected to a passage 59 bored at one end of the screw shaft 18, and this passage 59 communicates with the cylinder right chamber 11b.

In addition, the supply port 31 is connected to a pressure fluid supply source of flashing, and supplies pressure fluid to one valve chamber 25 and the other valve chamber 26.
A discharge port 32 in communication with is adapted to collect fluid ejected from the ejection nozzle 29,30 to the source.

As shown in detail in FIG. 4, the flapper valve 38 has a valve hole 41 drilled in the radial direction, and a damping plunger 43 pressed outward by a spring 42 is slidably fitted into the valve hole 41. It is inserted.

A large-diameter synthetic resin piece 44 is fixed to the tip of the damping plunger 43, and a small-diameter synthetic resin piece 45 is slidably inserted into a center hole formed in the synthetic resin piece 44.

These synthetic resin pieces 44 and 45 are made of a material with excellent heat resistance and abrasion resistance, such as polyacetal resin (trade name Delrin) or urethane rubber. The small diameter synthetic resin piece 45 is projected outward with respect to the large diameter synthetic resin piece 44,
It is joined to the inner peripheral surface of the sleeve valve member 19.

A pressure introduction hole 47 is opened at one end of the valve hole 41, and this introduction hole 47 is communicated with the valve chamber 25 via a flow path 48 formed between the steering shaft 39 and the torsion bar 40. .

As a result, pressure fluid whose pressure increases due to steering is introduced into the valve hole 41, and the fluid pressure is applied to the damping plunger 43.
toward the inner peripheral surface of the sleeve valve member 19.

Next, the operation of the power steering device having the above configuration will be explained.

When the steering handle is in the neutral state, both the first and second flapper valves 35 and 38 are located in the neutral state of the valve chambers 25 and 26, so that the pressure fluid supplied from the supply port 31 into the valve chamber 25 is distributed. into the nozzles 27, 28 and the ejection nozzle 29
, 30 to the valve chamber 26 and the discharge port 32.

In such a neutral state, the cylinder left and right chambers 11a, ll
Since the fluid pressure acting on b is balanced, the piston 10 does not operate and the steered wheels maintain a neutral state.

However, when the steering wheel is rotated, for example, to the right, road resistance is acting on the screw shaft 18, so the torsion bar 40 is twisted and the steering shaft 39 is rotated relative to the main valve member 20. .

As a result, the first and second flapper valves 35, 38 are tilted to the right and one of the distribution nozzles 28 and the jet nozzle 30
It acts to close the other distribution nozzle 27 and the other jet nozzle 29.

As a result, the pressure fluid supplied into the valve chamber 25 is forced to pass through the other distribution nozzle 27 and to the jet nozzle 30.
Since the amount of pressure fluid flowing out from the jet nozzle 30 is limited, the distributed pressure fluid is introduced into the cylinder right chamber 11b via the fluid passage 59 described above, and presses the piston 10 leftward to perform steering. Deflect the wheels to the right.

The small steering torque applied to the steering bundle by the steering person in this way is assisted by the movement of the piston 10, making it possible to easily deflect the steering wheel.

By the way, when the pressure of the pressure fluid increases due to the rotation of the bundle, it flows through the flow path 48 and the introduction hole 47 to the valve hole 4.
1 and is applied to the damping plunger 43.

However, when the pressure of the pressurized fluid is low, such as when traveling straight ahead, only the small diameter synthetic resin piece 45 is pressed against the inner peripheral surface of the sleeve valve member 19 by the spring 46. The sliding friction resistance caused by the piece 45 is small, and the feeling during straight running is improved, and bundle return is also improved.

However, when the fluid pressure increases, the vibration damping plunger 43 slides against the spring 46 and the large diameter synthetic resin piece 44
slides relative to the small diameter synthetic resin piece 45 and approaches the inner peripheral surface of the sleeve valve member 19.

When the pressure fluid introduced into the valve hole 41 reaches a predetermined pressure P1, the large-diameter synthetic resin piece 44 also joins to the inner peripheral surface of the sleeve valve member 19, and the contact area of the synthetic resin pieces 44, 45 increases. As the frictional resistance increases, the sliding frictional resistance due to the synthetic resin pieces 44 and 45 increases in stages, and this sliding frictional resistance
1, the vibrations generated in the relatively high pressure region P2 can be reliably prevented by the large sliding frictional resistance F1 created by the two synthetic resin pieces 44, 45.

FIG. 6 shows another embodiment of the present invention. In the embodiment described above, the reaction force acting on the damping plunger 43 by the spring 46 was received by the spring 42, but in this embodiment, The valve hole 141 is stepped,
The stepped portion 141a receives the reaction force acting on the damping plunger 43 by the spring 46, and other points are the same as the previous embodiment, so the same parts are given the same symbols. The explanation will be omitted.

Furthermore, in the above-described embodiment, the sliding frictional resistance was changed by increasing the contact area of the synthetic resin pieces in stages, but if the two synthetic resin pieces 44 and 45 have different coefficients of friction, The degree of freedom is provided by the variation of the sliding frictional resistance.

In the above-mentioned embodiments, a flapper type control valve has been described, but the present invention can be similarly applied to other types of control valves.

As described above, the present invention has a structure in which a damping plunger made of two synthetic resin pieces is fitted into a valve hole formed in one of two valve members that are movable relative to each other. , the contact area of the synthetic resin piece increases in stages according to the fluid pressure introduced into the valve hole, and as a result, when the pressure fluid is at low pressure, the sliding frictional resistance due to the synthetic resin piece can be extremely small, and the pressure fluid At high pressures, the sliding friction resistance of the synthetic resin piece can be increased to the level necessary to prevent vibration, and vibration of the valve member can be reliably prevented without impairing the feel or bundle return when traveling straight. The effect that can be achieved is achieved.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and Fig. 1 is a cross-sectional view of the power steering device, and Figs. 2 and 3 are cut along the lines ■-■ and ■-■ in Fig. 1, respectively. 4 is an enlarged sectional view of the main part of FIG. 3, FIG. 5 is a relationship diagram of sliding frictional resistance against fluid pressure, and FIG. 6 corresponds to FIG. 4 showing another embodiment of the present invention. FIG. 10... Piston, 11... Power cylinder, 12... Flapper type control valve, 13...
...Valve housing, 18...Screw shaft, 19.
...Sleeve valve member, 20...Main valve member, 25, 26...Valve chamber, 35°38...
・Flapper valve, 39... Steering shaft, 40...
...Torsion bar 41...Valve hole, 43...
... Vibration damping plunger, 44, 45 ... Synthetic resin piece, 46 ... Spring, 47 ...
・Introduction hole.

Claims (1)

[Scope of utility model registration request] a hydraulic motor connected to the steering wheel via a required connection means; a first valve member rotatably fitted in the valve housing and operatively connected to the hydraulic motor;
a second valve member that is accommodated in the valve member so as to be movable relative to the valve member and controls the pressure fluid supplied to the fluid pressure motor;
In a power steering device having a steering shaft connected to a valve member, a valve hole is formed in either one of the valve members, a damping plunger is slidably inserted into the valve hole, and the damping plunger is slidably inserted into the valve hole. Two synthetic resin pieces are provided at the tip of the vibration damping plunger and are fitted to be slidable relative to each other in the sliding direction of the vibration damping plunger, and one synthetic resin piece is inserted between the two synthetic resin pieces and the other valve A spring is inserted to press the valve member, and an introduction hole is opened for introducing pressure fluid into the valve hole in order to press the other synthetic resin piece against the other valve member when the fluid pressure generated by steering is high. A vibration damping device in a power steering device characterized by: