JPS588469A - Steering power controller of power steering device - Google Patents

Abstract

PURPOSE:To improve stability of steering at a high speed, in a power steering device of rotary valve type, by resisting rotation from a spring through a device, providing the device between an input shaft and worm shaft and applying back pressure in a recirculation oil passage to said device. CONSTITUTION:An axially directional hole 34 and a through hole 35, communicated to said hole 34 and extended at a right angle with the axial direction, are provided in the point end side of an input shaft 24. One head part of a torsion bar 36 is fitted and coupled by a pin to the axially directional hole 34, and steel balls 38 are in-out movably fitted to the through hole 35 by interposing a coil spring 37. The steel balls 38 are forcibly contacted to V-shaped recessed parts 39 provided in the internal peripheral surface of a worm shaft 19. The steel ball 38 is arranged to receive back pressure in a recirculation flow circuit, if the back pressure in the recirculation flow circuit is increased, the steel ball 38 is pressed into the through hole 35 against the spring 37, in this way, an input characteristic can be changed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power steering device, which includes a hook, a spool interlocked with an input shaft, and an outer sleeve interlocked with a worm shaft.
The present invention relates to a rotary valve type power steering device that includes a torsion bar that connects an input shaft and a worm shaft.

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. 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 fluidity 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 slows down the 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 restrictor. 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.

To explain the configuration of the present invention with reference to the embodiment shown in the drawings, in FIG. The flow rate is controlled by one pipe, which passes through the inside of the power steering device main body 8 and returns to the medullary tank 1 through a pipe 9. On the other hand, the oil outlet provided at lft*15 of the power steering device main body 8 is connected to the pipe. It is connected to tank 1 via IO. A signal detected by a vehicle speed sensor 11 mounted on the rear part of the transmission or an axle of the vehicle is amplified by a wave rectifying/amplifying circuit 12 to enough power to drive a solenoid 13 . #r, The hold control mechanism 5 is driven by a solenoid 13 and is a known mechanism that reduces Melk as the vehicle speed increases.

As shown in FIGS. 2 to 5, the power steering device main body 8 has the front cover 15 screwed into and fixed to the front side of the gear case 14, and the pulp housing 1 on the rear side.
6 are fitted and fixed. Further, a piston 17 is fitted into an oil well in the gear case 14, and the gear case 14 is divided into two cylinder chambers. A rack is provided on the lower surface of the piston 17 and meshes with a sector gear of output @18. The output shaft 18 is supported by the gear case 14 in a direction perpendicular 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 a ball that fits into the ball screw groove and rolls through the ball.
The ramshaft 19 and the piston 17 are fitted together. The tip of the worm shaft 19 is pivotally supported by the front cover 15 and supported in the axial direction on the thrust needle roller bearing side. A seal member 21 is provided between the outer peripheral surface of the tip of the worm shaft 19 and the cylindrical inner surface of the front cover 15 fitted thereto, and is connected to the pipe line 10 at the front i15 facing the end surface of the worm shaft 19. A second oil outlet 22 is provided. The rear end side of the worm 1ll119 has a flange-like connection part, which is pin-coupled to the outer sleeve B fitted to the pulp housing 16 on the outer circumferential surface, and fitted to the tip of the input shaft 24 on the inner circumferential surface. There is. The outer sleeve is supported in the pulp housing 16 by a thrust ball bearing 5 in the IIl+ force direction, and a spool is fitted on the inner peripheral surface. The spool rod is fitted onto the input shaft row with a gap and is connected with a pin, and the gap is part of the oil return circuit on the pulp side. Valve housing 16 uses human power IH 24 with needle roller bearing 27
The outer side of the oil seal 4 is sealed with an oil seal 4, and has an oil inlet 4 connected to the pipe 7 and a first oil outlet connected to the pipe 9.・Space 3 of the pulp housing housing the front d-vis thrust ball bearing 6
1 is provided with a relief pulp 32 that communicates with the gap on the inner peripheral surface of the spool and between it and the first oil outlet, and a throttle 33 is provided on the valve seat of the relief pulp. On the tip side of the input shaft, there is provided an axial hole and a return hole 35 in the direction perpendicular to the axis, which communicates with the hole in the axial direction. The head of the torsion bar is fitted in the axial direction and connected with a pin, and the two balls 38 can go in and out with the coil spring 37 in between. KN matches.

- The ball is pressed by a coil spring 37 into a V-shaped concave portion 39 provided on the inner peripheral surface of the flange-like connection portion of the worm shaft 19. The steel ball does not necessarily have to be a steel ball, and may be a plunger having a flat head. A sealing member 41 is provided at the fitting part between the tip of the human power shaft and the worm@1119, and the oil 2 in the oil return circuit on the pulp side is connected to the inner circumferential surface of the worm shaft 19 and the outer circumferential surface of the torsion bar 36. This prevents leakage into the space 42 between them. Torsion bar; (6 is the force that causes one 6 head to fit into the axial hole 3.4 of the input shaft as described above) The other head is also warm!
1) It is fitted into the shaft hole at the tip of 119 and is connected with a bottle, and there is a concave groove 4 on the outer surface of both heads that spans the entire length in the axial direction.
0 is provided, the through hole of the input shaft, and the space 42.
and a second oil outlet n. Pressure oil enters the inside of the outer sleeve B from the oil inlet 4 of the pulp housing through the circumferential groove 43 and introduction oil hole 44 of the outer sleeve shown in FIG. Excess oil enters the inside of the spool from the oil reservoir 47 of the spool, and flows through the gap between the spool 26 and the input vessel 4 to the oil return circuit on the pulp side. That is, the oil passes through the space Al in which the thrust ball @ receiver 5 is accommodated, passes through the aperture, and returns to the tank 1 from the first oil outlet side.

In addition, oil leaks from around the steel ball to the return circuit inside the worm shaft, enters the through hole 35, and enters the recess 40 of the torsion bar, the space 42 in the worm shaft, the groove 40 of the torsion bar, and the worm #. It returns to the tank 1 through the gap of one end bend and the oil outlet n of 42.

If the flow rate characteristics shown in Fig. 8 are given to the flow rate control mechanism 5, the flow rate of oil flowing into the oil filler 14 is small at high speeds, so
Since the flow rate flowing through the throttle is small and the pressure 9jJ due to the throttle is also low, the pressure in the space 3I of the valve housing is low. Therefore, since the pressure around the ball is also low, the ball is hardly affected by it, and the spring force of the set coil spring 37 presses the steel ball against the recess 39 on the inner surface of the worm sleeve. Gives resistance torque to the edge. At low speeds, the flow rate increases and the current flowing through the crest 33 also adds M, so a back pressure corresponding to the mC lid is generated in the space 31. When the pressure in the space 31 is -E, the return rti in the worm shaft with a pressure lower than that of the seven holes ((Since it is connected to the E'J path, the hydraulic force corresponding to the cross-sectional area of the steel ball 38: m It acts as a force to push the ball inward, and the coil & rice 37 & mami power is increased, and the set cart is decreased.The change in the input/output characteristics is shown in Figure 7, ] (Since the setting cart of the coil spring is added to the change in pressure sensitivity due to the flow rate of the loop, the input/output percentage can be changed greatly. This is a relief valve to prevent damage to the low-pressure coolant caused by a surge when the number of pumps 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. Identical to the example,
Between the pipe line 9 of the oil return circuit on the valve side and the pipe of tank 1,
A variable throttle device W33' is provided, and the solenoid 13 throttles the throttle when the vehicle speed is low, applies back pressure to the space 31 on the loop side, reduces the set load of the coil spring 37, and lightens the steering force, and reduces the steering force when the vehicle speed is high. The setting cart of the coil spring 37 is made effective without applying back pressure.

[Steering power node of the power steering device of the present invention constructed as described above] The control cover is configured to apply back pressure in the oil return circuit that changes due to the throttle to the pusher that is biased by a spring that resists the rotation of the human power shaft. The structure is such that the spring force is large and h9 is light at both speeds, and the spring force is good before the input/output characteristics change due to vehicle speed. This has the effect of increasing the amount of force added, and since the spring provides a steering reaction force, it also has 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 schematic diagram of the whistle, FIG. 2 is a vertical sectional view of the power steering device main body, and FIG. 3 is a full-1 [[ Cross section at line, 4th
The figure is a cross-sectional view at the Y-TV point in FIG. 2, FIG. 5 is a cross-sectional view at the ■-V point in FIG. 2, FIG. 6 is a circuit diagram showing another embodiment, and FIG. The output characteristic diagram, Figure 8, is
9 is an input/output characteristic diagram according to the prior art. Explanation of symbols 1: Tank, 3: Pump, 5: Flow lid control mechanism, 8.8'
: Power steering device main body, 11 2nd vehicle speed sensor, 12: Fire amplification circuit, 13: Solenoid, 14 2nd gear case, 15
: Front lid, 16: Valve housing, 19; Worm shaft,
21: Seal member, one outer sleeve, Sae: Input shaft, 2b = Spool, 31: Space, 32: Lilium pulp, O: Soft, A: Printable device, A: W 4 hole,
36: )-john bar, 37: coil spring, 38: steel ball, 39: recess, 40: groove, 41: seal member, 42
;space. Patent applicant NSK Ltd./f3 [F] f4 Illustrated! Koma! 7II! I Human force o 8 Polished car speed o゛? Figure 8

Claims (1)

[Claims] (1) In a rotary valve type power steering device comprising a spool interlocking with an input shaft, an outer sleeve interlocking with a worm shaft, and a torsion bar connecting the input shaft and the worm shaft, the inner surface of the worm shaft A recess is provided, a through hole is provided in the axis-perpendicular force direction in the input shaft, a spring and a presser are fitted into the through hole, the presser is pressed against the four parts by spring force, and the through hole is connected to the worm shaft. At the same time, the presser is placed in the oil return circuit on the valve side, and a throttle is provided in the oil return circuit on the pulp side, and the back pressure is used to control the outside and inside of the presser. A steering force opening side device of a power steering device, characterized in that a differential pressure is generated between the two.