JP3007508B2 - Steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering apparatus having a mechanism capable of returning a steering wheel of a vehicle to a straight steering position.

[0002]

2. Description of the Related Art Generally, a steering wheel of a vehicle naturally returns to a straight-ahead steering position without conscious operation by setting wheel alignment.

However, as in the negative camber lower side of the wheel is extending outward in the vehicle employing the wheel alignment force to spontaneous reversion is less than usual in the straight steering position of the handle, straight running condition and so curvature This is not a problem when traveling on a road that is not large, but when traveling on a road with a large curvature that requires steering to near the steering limit, turning in the straight steering direction after increasing the steering angle It is necessary to consciously and positively perform this operation more than in a vehicle employing normal wheel alignment, and thus there is a problem that the operation feeling is reduced.

In a vehicle equipped with a power steering device, when the driver does not notice that the steering limit has been reached until the steering wheel is locked, a steering assist force acts until the steering wheel is locked. Therefore, an impact acts at the steering limit, and the operation feeling at the time of shifting to the straight steering direction after increasing the steering angle is reduced.

An object of the present invention is to provide a steering device that can solve the above-mentioned problems of the prior art.

[0006]

A steering apparatus according to the present invention includes an operating member that reciprocates in response to steering of a steering wheel, and a spring that generates an elastic force for returning the operating member to a straight steering position. Has a nonlinear characteristic in which the rate of increase of the elastic force with respect to the steering angle is greater in a range where the steering angle is large than in a range where the steering angle is small.

[0007]

According to the structure of the present invention, the handle tends to rotate in the straight steering direction by the elastic force of the spring acting on the operating member. Since the rate of increase of the elastic force with respect to the steering angle of the spring is larger in a range where the steering angle is large than in a range where the steering angle is small, in a normal traveling state where the vehicle runs on a road with a not so large curvature, the steering wheel is rotated in the straight steering direction. Since the elastic force to be applied is small and the steering resistance does not increase, it does not affect the operation feeling. On the other hand, when the steering angle increases, the elastic force for rotating the steering wheel in the straight steering direction increases, so the force for rotating the steering wheel in the straight steering direction when turning in the straight steering direction after increasing the steering angle increases, Further, the driver can notice that the steering wheel has reached the vicinity of the steering limit.

[0008]

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

A rack and pinion type hydraulic power steering device 1 shown in FIG. 1 has a cylindrical input shaft 2 connected to a steering wheel H of a vehicle, and an output shaft 3 connected to the input shaft 2 via a torsion bar 6. Is provided. One end of the torsion bar 6 is connected to the input shaft 2 via the pin 4, and the other end is connected to one end of the output shaft 3 via the serration 5, and the input shaft 2 and the output shaft 3 are connected by the torsion of the torsion bar 6. Relative rotation. The input shaft 2 is supported by a valve housing 7 via a bearing 8, and is supported at one end of the output shaft 3 via a bush 12. The output shaft 3 is supported by the rack housing 9 via bearings 10 and 11. A pinion 15 is formed on the output shaft 3, a steering rack 16 meshing with the pinion 15 is supported by a support yoke 40, and steering wheels (not shown) are connected to the steering rack 16. As a result, the rotation of the input shaft 2 caused by the steering is transmitted to the pinion 1 via the torsion bar 6.
5 and the rotation of the pinion 15 causes the steering rack 16 to move in the vehicle width direction.
The vehicle is steered by the movement of the vehicle. Note that an oil seal 41 is attached between the upper portion of the valve housing 7 and the input shaft 2, and an oil seal 42 is attached between the inner periphery of the lower portion of the valve housing 7 and the output shaft 3.

The other end of the output shaft 3 is connected to a rack housing 9.
And a pinion 60 is formed on the outer periphery of the protruding portion. A pair of racks (operating members) 61 and 62 that mesh with the pinion 60 are covered by a rack cover 63. The rack cover 63 is attached to the rack housing 9 by bolts 64. The bearing 11 supporting the output shaft 3 includes an outer ring formed on the rack housing 9 by a lock nut 14a and an inner ring formed on the lock nut 14a.
b, it is fixed to the output shaft 3 and the movement in the axial direction is stopped.

As shown in FIGS. 2 and 3, both racks 61,
Reference numeral 62 is disposed with the pinion 60 interposed therebetween so that the axis is parallel to the axis of the steering rack 16, and reciprocates in opposite directions when the pinion 60 is rotated by steering. FIG. 2 shows the relative positions of the two racks 61 and 62 in the straight steering state, and FIG. 3 shows the two racks 61 and 6 in the left or right steering state.
2 shows the relative position. A plurality of elastic members 65 made of synthetic resin are attached to each of the racks 61 and 62.
Each of the racks 61 and 62 is supported by the inner surface of the rack cover 63 via the rack 5. Further, since the respective racks 61 and 62 are pressed against the pinion 60 by the elastic force of the elastic member 65, the racks 61 and 62 reciprocate smoothly without rattling.

At each end of the rack cover 63, a pair of female screw holes 63a are formed.
A male screw 66 having a tool engagement hole is screwed into the screw. Compression coil springs 70, 71, 72, 73 compressed by the male screws 66 and the racks 61, 62 are inserted into the rack cover 63. Each compression coil spring 70, 71,
The racks 72, 73 apply an elastic force for returning the racks 61, 62 to the straight steering position shown in FIG.
To act on.

Each compression coil spring 70, 71, 72, 73
Has a large portion and a small portion of the pitch between the coils, so that, as shown in FIG. 4, the rate of increase of the elastic force with respect to the steering angle is greater in a large steering angle range than in a small steering angle range. It has non-linear characteristics.
In the present embodiment, the elastic force is weak until the steering wheel rotation angle is around ± 180 °, and the rate of increase of the elastic force increases beyond that point.

A hydraulic cylinder 20 is provided as a hydraulic actuator for applying a steering assist force. The hydraulic cylinder 20 includes a cylinder tube configured by the rack housing 9 and a piston 21 integrated with the steering rack 16. Hydraulic control valves 30 for supplying pressure oil in accordance with the steering direction and the steering resistance are provided in oil chambers 22 and 23 partitioned by the piston 21.

The control valve 30 has a cylindrical valve member 31 inserted into the valve housing 7 so as to be relatively rotatable and surrounding the input shaft 2. The valve member 31 is connected to the output shaft 3 via a pin 32 so as to rotate together therewith. An inlet port 34 connected to a pump 33 and an outlet port 36 connected to a tank 35 are provided between the valve member 31 and the valve housing 7.
And a first port 37 connected to one oil chamber 22 of the hydraulic cylinder 20 and a second port 38 connected to the other oil chamber 23. Each port 34, 36,
37, 38 communicate via an oil passage between the input shaft 2 and the valve member 31, and the opening of the oil passage is adjusted by the relative rotation between the input shaft 2 and the valve member 31 due to the torsion bar 6 being twisted. Is done. That is, as shown in FIG. 5, eight first concave portions 50 are formed in the inner periphery of the valve member 31 along the axial direction at equal intervals in the circumferential direction. Eight second concave portions 51 are formed at equal circumferential intervals on the outer periphery of the input shaft 2 so as to oppose the first concave portions 50 in the circumferential direction. The first recess 50 is provided with the valve member 3.
One that communicates with the first port 37 via one flow path 53 and one that communicates with the second port 38 via the flow path 54 of the valve member 31 are alternately arranged in the circumferential direction. The second recess 51 is connected to the inlet port 3 through the flow path 55 of the valve member 31.
4 and the one communicating from the lower channel 52a of the input shaft 2 to the outlet port 36 from the upper channel 52b of the input shaft 2 via the channel 52c between the inner and outer circumferences of the torsion bar 6 and the input shaft 2. , And are alternately arranged in the circumferential direction. FIG. 5 shows a state in which steering is not performed. The inlet port 34 and the outlet port 36 communicate with each other, the oil flowing from the pump 33 into the control valve 30 returns to the tank 35, and no steering assist force is generated. When the torsion bar 6 is twisted due to steering resistance generated by steering to the left or right, and the valve member 31 and the input shaft 2 rotate relative to each other, the relative position between the first concave portion 50 and the second concave portion 51 changes, and the inlet port 34 is changed. The opening degree of the oil passage A between the first port 37 and the first port 37 increases, the opening degree of the oil passage B between the first port 37 and the outlet port 36 decreases, and the inlet port 34 and the second port 38 , The opening degree of the oil passage C between the second port 38 and the outlet port 36 increases. As a result, pressure oil having a pressure corresponding to the steering direction and the steering resistance is supplied to one oil chamber 22 of the hydraulic cylinder 20, and the oil flows from the other oil chamber 23 to the tank 35 and returns to one of the left and right sides of the vehicle. Is applied from the hydraulic cylinder 20 to the steering rack 16. When the steering is performed to the right or left side, the valve member 31 and the input shaft 2 relatively rotate in the opposite direction to the case where the steering is performed to the left or right side.
, The opening of the oil passage B increases, the opening of the oil passage C increases, and the opening of the oil passage D decreases. As a result, the steering assist force to the other side of the vehicle acts on the steering rack 16 from the hydraulic cylinder 20.

According to the above configuration, the handle H tends to rotate in the straight steering direction by the elastic force of the springs 70, 71, 72, 73 acting on the racks 61, 62. The rate of increase in the elastic force of the springs 70, 71, 72, 73 with respect to the steering angle is greater in a large steering angle range than in a small steering angle range. Therefore, when the vehicle is traveling on a road with a small curvature, the elastic force for rotating the steering wheel in the straight steering direction is small and the steering resistance is not increased. Waste can be prevented. On the other hand, when the steering angle increases, the elastic force for rotating the steering wheel H in the straight steering direction increases. Therefore, even when the wheel alignment of the steering wheel is such that the force for returning the steering wheel to the straight steering position becomes smaller like a negative camber, the steering in the straight steering direction after increasing the steering angle is usually performed. It is not necessary to be more conscious and aggressive than a vehicle that adopts the wheel alignment, and the operation feeling can be improved. In addition, since the driver can notice that the steering wheel has reached the vicinity of the steering limit before the steering wheel is locked, it is possible to prevent the effect of an impact due to the locking of the steering wheel at the steering limit, and to perform the straight steering direction after increasing the steering angle. The steering can be performed with a natural feeling, and the operation feeling can be improved. In the above embodiment, the racks 61, 62
Since the springs 70, 71, 72 and 73 are mounted outside the rack housing 9, the structure of the steering device itself is not complicated at all. Also, a pair of racks 6
The pinions 60 are sandwiched between the racks 61 and
2 is pressed against the pinion 60, so that the rack 61,
The engagement between the pinion 62 and the pinion 60 can be reliably maintained.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the present invention is applied to a rack and pinion type power steering device, but may be applied to a manual steering device. Although the rack is shown as an operating member that reciprocates in response to steering of the steering wheel, the output shaft can be returned to the straight steering position by the elastic force of a helical spring having nonlinear characteristics, or a ball in a ball screw type steering device can be used. The nut may be returned to the straight steering position by the elastic force of a spring having nonlinear characteristics.

[0018]

According to the steering apparatus of the present invention, when the vehicle adopting a negative camber or a power steering apparatus travels on a road with a large curvature, the vehicle can be steered in the straight steering direction after increasing the steering angle. Operation feeling can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a hydraulic power steering device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view for explaining the operation of the embodiment of the present invention.

FIG. 4 is a diagram showing spring characteristics of an embodiment of the present invention.

FIG. 5 is a partial plan sectional view of a rotary valve according to an embodiment of the present invention.

[Description of Signs] H Handle 61, 62 Rack 70, 71, 72, 73 Spring

Claims (1)

(57) [Claims] An operating member that reciprocates in response to steering of a steering wheel, and a spring that generates an elastic force for returning the operating member to a straight steering position, wherein the spring has an increasing ratio of the elastic force to the steering angle. A steering device having a non-linear characteristic in which a steering angle is larger in a large range than in a small range.