JPH0143672B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power steering device, and more particularly to a rotary steering device including a valve rotor that is interlocked with an input shaft, an outer sleeve that is interlocked with a worm shaft, and a torsion bar that connects the input shaft and the worm shaft. Pertains to valve type power steering device.

Conventional power steering devices have the disadvantage that the steering force is too small at high speeds, making the steering unstable.In order to increase the sense of stability at high speeds, various devices have been proposed that change the input/output characteristics depending on the vehicle speed. Ori,
The type that controls the supply flow rate is often used because the control mechanism is simple and the structure of the power steering device body can be used as is with general specifications. However, this type has a drawback that even if it provides the flow rate characteristics as shown in FIG. 8, the amount of change in the input/output characteristics is small as shown in FIG. 9.

In order to compensate for this drawback of the flow rate control type, the present invention provides a device that resists rotation by a spring between the input shaft and the worm shaft, which rotate relative to each other together with the valve element of the rotary valve, and provides a restriction. This device is designed to allow the hydraulic pressure of the oil return circuit, which changes due to the generation of back pressure, to act on this device.

That is, the configuration of the present invention is a rotary valve type power steering system including a valve rotor 26 that is linked to an input shaft 24, an outer sleeve 23 that is linked to a worm shaft 19, and a torsion bar 36 that connects the input shaft and the worm shaft. A device main body 8, a pump 3 that supplies pressure oil to the main body, an oil supply circuit 7 that connects the pump and the main body, oil return circuits 9, 9' extending from the main body to the tank, and In the steering force control device for a power steering device, the reaction force generation mechanism includes a recess 39 provided on the inner surface into which the tip of the input shaft of the worm shaft is fitted, and a recess 39 in the recess. a through hole 35 provided in a direction perpendicular to the axis of the input shaft that opens toward the input shaft; a presser 38 fitted in the through hole; and an elastic member 37 fitted in the through hole to press the presser against the recess.
, a communication path 31 that communicates between the recess and the presser and the oil return circuit, and throttle mechanisms 33 and 33' provided in the oil return circuit, and the back pressure from the throttle mechanism This is a steering force control device for a power steering device, characterized in that the steering reaction force is controlled by pressing a pusher into the through hole against the elastic force of the elastic member.

To explain the configuration of the present invention with reference to the embodiment shown in the drawings, in FIG. The flow rate is controlled and flows into the pipe line 7. Excess oil flows through pipe 6 to tank 1.
Return to The oil entering the power steering device body 8 from the pipe 7 passes through the inside of the power steering device main body 8 and enters the pipe 9.
On the other hand, an oil outlet provided in the front lid 15 of the power steering device main body 8 is connected to the tank 1 via a conduit 10. A signal detected by a vehicle speed sensor 11 mounted on the rear part of a vehicle transmission or an axle is amplified by a wave rectifying/amplifying circuit 12 to enough power to drive a solenoid 13. The flow rate control mechanism 5 is driven by a solenoid 13 and is a known mechanism that reduces the flow rate as the vehicle speed increases. As shown in FIGS. 2 to 5, the power steering device main body 8 is connected to the gear case 1.
The front cover 15 is screwed and fixed to the front side of the valve housing 4, and the valve housing 16 is screwed to the rear side of the valve housing 16.
are fitted and fixed. Further, the piston 17 is oil-tightly fitted into the gear case 14.
It is divided into two cylinder chambers. piston 1
A rack is provided on the lower side of the shaft 7 and meshes with the sector gear of the output shaft 18. Output shaft 1
8 is supported by the gear case 14 in a direction orthogonal to the piston 17, and rotates as the piston 17 moves in the axial direction. A ball screw groove is provided on the inner circumferential surface of the piston 17, and the worm shaft 19 and the piston 17 fit together via balls that fit into the ball screw groove and roll.
The tip of the worm shaft 19 is pivotally supported by the front cover 15 and supported in the axial direction by a thrust needle roller bearing 20. A sealing member 21 is provided between the outer circumferential surface of the tip end of the worm shaft 19 and the cylindrical inner surface of the front cover 15 fitted thereto, and a sealing member 21 is provided between the front cover 15 and the conduit 10 opposite to the end surface of the worm shaft 19. A second connecting oil outlet 22 is provided. The rear end side of the worm shaft 19 is a flange-like connection part, and the outer sleeve 23 fitted into the valve housing 16
The input shaft 2 is pin-coupled on the outer circumferential surface, and the input shaft 2 is connected on the inner circumferential surface.
It fits into the tip of 4. Outer sleeve 2
3 is a thrust ball bearing 25 in the valve housing 16
is supported in the axial direction by the valve rotor 2 on the inner peripheral surface.
It is mated with 6. The valve rotor 26 is externally fitted onto the input shaft 24 with a gap and is connected to the input shaft 24 by a pin, and the gap forms part of the oil return circuit on the valve side. The valve housing 16 supports an input shaft 24 with a needle roller bearing 27 and has an oil seal 28 sealed on the outside thereof, and has an oil inlet 29 connected to the pipe 7 and a first oil It has an exit 30. The space 31 of the valve housing housing the thrust ball bearing 25 is connected to the valve rotor 2.
6, and a relief valve 32 is provided between the first outlet 30 and the first outlet 30.
A throttle 33 is provided on the valve seat of the relief valve. An axial hole 34 is provided on the tip side of the input shaft 24.
A through hole 35 in the direction perpendicular to the axis is provided which communicates with this. The head of one of the torsion bars 36 is fitted into the axial hole 34 and connected with a pin, and two steel balls 38 are fitted into the through hole 35 with a coil spring 37 in between so that they can go in and out. are doing. The steel ball 38 is attached to the coil spring 3 in a V-shaped groove-shaped recess 39 provided on the inner peripheral surface of the flange-like connection part of the worm shaft 19.
It is pressed at 7. The steel ball 38 does not necessarily have to be a steel ball, and may be a plunger having a spherical head. Moreover, the gap between the steel ball 38 and the recess 39 and the inner peripheral surface of the valve rotor 26 communicate with each other at the end of the gap on the steel ball 38 side. A seal member 41 is provided on the fitting surface between the tip of the input shaft and the worm shaft 19, and the oil in the oil return circuit on the valve side is connected to the inner peripheral surface of the worm shaft 19 and the torsion bar 3.
This prevents leakage into the space 42 between the outer circumferential surface of 6 and the outer peripheral surface of 6. As described above, one head of the torsion bar 36 fits into the axial hole 34 of the input shaft, and the other head also fits into the shaft hole at the tip of the worm shaft 19 and is connected with a pin. A groove 40 extending over the entire length in the axial direction is provided on the outer surface of both heads, communicating the through hole 35 of the input shaft, the space 42, and the second oil outlet 22. Pressure oil flows from the oil inlet 29 of the valve housing to the circumferential groove 43 and introduction oil hole 44 of the outer sleeve shown in FIG.
The excess oil enters the inside of the outer sleeve 23 through the oil holes 45 and 46, and is sent to the cylinder chambers on both sides of the piston 17 through the oil holes 45 and 46. , flows from the gap between the valve rotor 26 and the input shaft 24 to the valve-side oil return circuit. That is, the oil passes through the space 31 in which the thrust ball bearing 25 is accommodated, passes through the throttle 33, and returns to the tank 1 from the first oil outlet 30. In addition, a steel ball 38 is connected to the oil return circuit inside the worm shaft.
It leaks from the periphery of the torsion bar and enters the through hole 35, and the concave groove 40 of the torsion bar, the space 42 in the worm shaft,
The oil returns to the tank 1 through the groove 40 of the torsion bar, the gap in the end face of the worm shaft, and the second oil outlet 22.

Now, the flow rate characteristics as shown in Fig. 8 are determined by the flow rate control mechanism 5.
At high speed, the flow rate of oil flowing into the oil inlet 29 is small, so the flow rate flowing into the throttle 33 is also small, and the pressure effect due to the throttle is small, so the pressure in the space 31 of the valve housing is low. Therefore, steel ball 3
Since the pressure around the worm shaft 8 is also low, the steel ball 38 is hardly affected by it, and the set spring force of the coil spring 37 presses the steel ball 38 against the recess 39 on the inner surface of the worm shaft, applying a resistance torque to the input shaft 24. give. At low speeds, the flow rate increases and the flow rate flowing through the restrictor 33 also increases, creating a high back pressure in the space 31 corresponding to the flow rate. When the pressure in the space 31 increases,
Since the through hole 35 is connected to an oil return circuit in the worm shaft with a lower pressure, the hydraulic pressure corresponding to the cross-sectional area of the steel ball 38 acts as a force to push the steel ball 38 inward, and the coil spring 37 It appears that the set load has decreased. Figure 7 shows this as a change in the input/output characteristics.In addition to the change in pressure sensitivity due to the flow rate of the valve, the set load of the coil spring is added, making it possible to greatly change the input/output characteristics. Become. The relief valve 32 is a relief valve for preventing damage to the low pressure seal due to surge pressure when the flow rate suddenly increases.

FIG. 6 shows another embodiment of the present invention in which the throttle is provided outside the main body of the power steering device, and members common to those in the first embodiment are given the same reference numerals. The power steering device main body 8' is the same as the first embodiment except that the relief valve and the throttle are removed and the space 31 and the outlet 30 are directly connected through a hole, and the oil return circuit conduit 9' on the valve side is A variable throttle device 33' is provided between the pipe of the tank 1 and the solenoid 13, and when the vehicle speed is low, the solenoid 13 throttles the valve to apply back pressure to the space 31 on the valve side, reducing the set load of the coil spring 37 and increasing the steering force. It is made lighter and opens at high speeds so that no back pressure is applied, and the set load of the coil spring 37 is applied.

The steering force control device for the power steering device of the present invention configured as described above applies the back pressure of the oil return circuit, which is varied by the throttle, to the spring-biased pusher that resists the rotation of the input shaft. , the spring force is large at high speeds, making the steering heavy, and at low speeds, the spring force is small, making the steering light.This provides good stability at high speeds, and changes in input/output characteristics depending on vehicle speed. This has the effect of increasing the amount by the amount of spring force added, and since the spring provides a steering reaction force, there is also the effect of improving the steering feel when driving straight ahead.

[Brief explanation of drawings]

1 to 7 show embodiments of the present invention,
Fig. 1 is a circuit diagram, Fig. 2 is a longitudinal cross-sectional view of the power steering device main body, Fig. 3 is a cross-sectional view taken along the - line in Fig. 2, and Fig. 4 is a cross-sectional view taken along the - line in Fig. 2. , Fig. 5 is a cross-sectional view taken along the - line in Fig. 2, Fig. 6 is a circuit diagram showing another embodiment, Fig. 7 is an input/output characteristic diagram, Fig. 8 is a flow rate characteristic diagram, and Fig. 9 is a diagram showing a flow rate characteristic. FIG. 3 is an input/output characteristic diagram according to the prior art. Explanation of symbols, 1: Tank, 3: Pump, 5: Flow rate control mechanism, 8, 8': Power steering device main body, 1
1: Vehicle speed sensor, 12: Rectifier amplifier circuit, 13:
Solenoid, 14: Gear case, 15: Front cover, 1
6: Valve housing, 19: Worm shaft, 2
1: Seal member, 23: Outer sleeve, 2
4: Input shaft, 26: Valve rotor, 31: Space, 3
2: leaf valve, 33: throttle, 33': variable throttle device, 35: through hole, 36: torsion bar,
37: Coil spring, 38: Steel ball, 39: Recess, 4
0: Concave groove, 41: Seal member, 42: Space.

Claims (1)

[Claims] 1 A rotary valve type power steering device main body comprising a valve rotor interlocking with the input shaft, an outer sleeve interlocking with the worm shaft, and a torsion bar connecting the input shaft and the worm shaft, and supplying pressure oil to the main body. Steering force control of a power steering device including a pump that connects the pump and the main body, an oil return circuit that extends from the main body to a tank, and a reaction force generation mechanism provided in the main body. In the device, the reaction force generating mechanism includes a recess provided on an inner surface into which a tip of the input shaft of the worm shaft is fitted;
a through hole provided in the direction perpendicular to the axis of the input shaft that opens toward the recess, a pusher fitted into the through hole, and an elastic member fitted into the through hole to press the pusher into contact with the recess. a communication path that communicates between the recess and the pusher and the oil return circuit; and a throttle mechanism provided in the oil return circuit, and the pusher is made elastic by back pressure from the throttle mechanism. A steering force control device for a power steering device, characterized in that the steering reaction force is controlled by pressing the member into the through hole against the elastic force of the member.