JPH0143671B2 - - 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. There is.
Among them, 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 the disadvantage that even if the flow rate characteristics are varied, the input/output characteristics cannot be changed significantly. Separately, for the type that controls hydraulic reaction force, it is necessary to install a mechanism within the power steering system that converts the reaction oil pressure into reaction force, and this mechanism uses a piston to apply a couple force to the input shaft. There are several ways to apply this, but in either case it is necessary to introduce the reaction hydraulic pressure from outside the steering device body, so one oil groove and one seal groove are added to the outer circumference of the outer sleeve, and a piston is added. A space is required for accommodation, and the axial dimension of the valve becomes large.

The present invention aims to improve the above-mentioned drawbacks of the hydraulic reaction control type.

In order to achieve this object, the present invention provides a rotary valve type power steering device in which a recess is provided on the inner surface of the worm shaft, a through hole is provided in the input shaft in a direction perpendicular to the axis, and a spring and a presser are fitted into the through hole. The gist of the present invention is to press the presser against the recessed portion by a spring force, introduce a reaction hydraulic pressure into the inside of the worm shaft, and communicate the inside of the worm shaft with the through hole.

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. It includes a device main body 8, a pump 3 that supplies pressure oil to the power steering device main body, and a reaction hydraulic pressure generator 5 disposed between the pressure oil path between the pump and the power steering device main body. In the steering force control device for a power steering device, a recess 39 is provided on the inner surface into which the tip of the input shaft of the worm shaft is fitted, a through hole 35 is provided in the input shaft in a direction perpendicular to the axis, and a spring 37 and a spring 37 are provided in the through hole. The presser 38 is fitted, the presser is pressed against the recessed portion by a spring force, and the oil inlet 22 is inserted into the front cover 15 that covers the tip side of the worm shaft.
, an oil passage 40 that communicates between the oil inlet and a space 33 between the inner circumferential surface of the worm and the outer circumferential surface of the torsion bar, and an oil passage 40 that communicates the space and the through hole; This is a steering force control device for a power steering device, characterized in that an oil inlet and the reaction oil pressure generating device are connected through a pipe line 7, and reaction oil pressure is introduced into the through hole.

To explain this with respect to the embodiment shown in the figure, in FIG. 1, oil sucked up from a tank 1 through a pipe 2 to a pump 3 enters a reaction hydraulic pressure generator 5 through a pipe 4, and is diverted. It flows from the pipe 6 into the inside of the valve housing of the power steering device main body 8.
It returns to the tank 1 through a conduit 9 that enters the power steering device main body 8. A signal detected by a vehicle speed sensor 10 mounted on the rear part of a vehicle transmission or an axle is amplified by a wave rectifying/amplifying circuit 11 to enough power to drive a solenoid 12. The reaction hydraulic pressure generator 5 is driven by a solenoid 12,
The oil pressure, which increases as the vehicle speed increases, is transmitted to the inside from the oil inlet provided in the front cover of the power steering device main body 8 via a pipe 7. Fig. 6 shows a state where the vehicle speed is low; When the amount increases, the piston moves in the direction of the arrow, resulting in a state as shown in FIG. 7, and the oil pressure in the pipe line 7 increases. The structure of the reaction hydraulic pressure generating device 5 is not limited to the above embodiment, and may be of various known structures. Also,
The pipe line 6 connecting the reaction force hydraulic pressure generating device 5 and the power steering device main body 8 may be directly connected to the pipe line 4 from the pump 3. As shown in FIGS. 2 to 5, the power steering device main body 8 includes a gear case 14.
The front cover 15 is screwed and fixed to the front side of the valve, and the valve housing 16 is fitted and fixed to the rear side. Further, a piston 17 is oil-tightly fitted into the gear case 14, and the gear case 14 is divided into two cylinder chambers. piston 17
A rack is provided on the lower side of the output shaft 1.
It meshes with sector gear number 8. Output shaft 18
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 seal member 21 is provided between the outer circumferential surface of the tip of the worm shaft 19 and the cylindrical inner surface of the front cover 15 fitted thereto, and a seal member 21 is provided between the front cover 15 and the conduit 7 opposite to the end surface of the worm shaft 19. A connecting second oil inlet 22 is provided. The rear end side of the worm shaft 19 is a flange-shaped connection part, which is pin-coupled to the outer sleeve 23 fitted to the valve housing 16 on the outer peripheral surface, and fitted to the tip of the input shaft 24 on the inner peripheral surface. ing. The outer sleeve 23 is supported in the axial direction by a thrust ball bearing 25 in the valve housing 16, and is fitted with a valve rotor 26 on its inner peripheral surface. The spool 26 is externally fitted onto the input shaft 24 with a gap and is connected to the input shaft 24 with a pin, and the gap forms part of an oil return circuit. The hull housing 16 has an input shaft 24 supported by a needle roller bearing 27 and is sealed on the outside with an oil seal 28, and has a first oil inlet 2 connected to the pipe line 6.
9 and an oil outlet 30 connected to the conduit 9. A space 31 of the valve housing housing the thrust ball bearing 25 communicates with a gap in the inner peripheral surface of the spool 26. An axial hole 34 and an axially perpendicular through hole 35 communicating with the axial hole 34 are provided on the tip side of the input shaft. One head of a torsion bar 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 pressed by a coil spring 37 into a V-groove-shaped recess 39 provided on the inner peripheral surface of the flange-like connection portion of the worm shaft 19 . The steel ball 38 does not necessarily have to be a steel ball, and may be a plunger having a spherical head. A sealing member 32 is provided on the fitting surface between the tip of the input shaft and the worm shaft 19, and a space 33 between the inner peripheral surface of the worm shaft 19 and the outer peripheral surface of the torsion bar 36 and the spool 2 are provided.
The oil return circuit on the inner peripheral surface of No. 6 is cut off. 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 concave groove 40 (oil passage) extending over the entire length in the axial direction is provided on the outer surface of both heads, and communicates with the through hole 35 of the input shaft, the space 33, and the second oil inlet 22. . The main flow of pressure oil flowing through the pipe line 6 enters the inner side of the outer sleeve 23 from the first oil inlet 29 of the valve housing through the circumferential groove 41 and introduction oil hole 42 of the outer sleeve shown in FIG. Divided into oil hole 43,
44 to the cylinder chambers on both sides of the piston 17, excess oil enters the inside of the spool 26 through the oil hole 45 of the valve rotor, and the thrust ball bearing 25 is accommodated through the gap between the valve rotor 26 and the input shaft 24. The oil returns to the tank 1 from the oil outlet 30 through the space 31 where the oil is removed. On the other hand, the reaction oil pressure that reaches the second oil inlet 22 from the reaction oil pressure generator 5 through the pipe line 7 and fills the space 33 inside the worm shaft and the through hole 35 is returned from around the steel ball 38. There is almost no flow other than leakage into the oil circuit, and the pressure increases or decreases as the vehicle speed increases or decreases. Accordingly, the steel ball 38 is pressed against the recess 40 on the inner surface of the worm shaft by the reaction hydraulic pressure and the spring force of the coil spring 37, producing a reaction force corresponding to the vehicle speed. The spring force of the coil spring 37 may be set to such an extent that the steel ball 38 and the recess 40 are not separated, and the reaction force may be generated entirely by hydraulic pressure, but the spring force alone can generate a certain amount of reaction force. It may be made to occur.

The steering force control device for the power steering device of the present invention configured as described above transmits the reaction hydraulic pressure to the reaction force generating mechanism through the inside of the worm shaft, so it is similar to a conventional valve in which the reaction hydraulic pressure is introduced. In comparison, there is no need to provide an oil groove in the outer sleeve to introduce reaction force hydraulic pressure and a seal groove to block it in the axial direction, and there is no reaction force generation mechanism inside the valve. This has the effect of shortening the axial length of. In addition, since no reaction hydraulic pressure is introduced into the valve, it is possible to control the reaction force using external hydraulic pressure without changing the current layout of the non-speed sensitive power steering system. There is also the effect of adding a set load due to the coil spring.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a circuit diagram, FIG. 2 is a longitudinal sectional view of the power steering device main body, and FIG.
The figure is a cross-sectional view taken along the - line in Figure 2, Figure 4 is a cross-sectional view taken along the - line in Figure 2, Figure 5 is a cross-sectional view taken along the - line in Figure 2, and Figures 6 and 7. FIG. 2 is a longitudinal cross-sectional view of the reaction force hydraulic pressure generating device. Explanation of symbols, 1: Tank, 3: Pump, 5: Reaction hydraulic pressure generator, 8: Power steering device main body, 10:
Vehicle speed sensor, 11: Wave rectifying amplifier circuit, 12: Solenoid, 14: Gear case, 15: Front lid, 16:
Valve housing, 19: Worm shaft, 21: Seal member, 23: Outer sleeve, 24: Input shaft, 26: Valve rotor, 31: Space, 32: Seal member, 33: Space, 35: Through hole, 36: Torsion bar, 37: Coil spring, 38: Steel ball, 3
9: recessed portion, 40: recessed groove.

Claims (1)

[Claims] 1. A rotary valve type power steering device body 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, and a main body of the power steering device. A steering force control device for a power steering device including a pump for supplying pressure oil and a reaction force hydraulic pressure generating device disposed between a pressure oil path between the pump and the power steering device main body, wherein the worm shaft A recess is provided on the inner surface into which the tip of the input shaft is fitted, a through hole is provided in the input shaft in a direction perpendicular to the axis, a spring and a presser are fitted into the through hole, and the presser is pressed into the recess by spring force. an oil inlet in a front cover that covers the tip side of the worm shaft, an oil passage that communicates the oil inlet with a space between the inner circumferential surface of the worm and the outer circumferential surface of the torsion bar, and the space and the through hole. and an oil passage communicating with the through hole, the oil inlet and the reaction oil pressure generating device are connected by a pipe line, and the reaction oil pressure is introduced into the through hole. Steering force control device.