JPH01160781A - Steering gear ratio control mechanism - Google Patents

Abstract

PURPOSE:To aim at ensuring the stability and safety of manipulation by enabling the steering ratio in accordance with a vehicle speed, and by safely maintaining the operation of steering even though a steering angle ratio control motor fails. CONSTITUTION:A planetary gear 17 is disposed between a sun gear 14 coupled to an input shaft 12 and an internal gear 15 and is meshed to them. A gear 20 integrally incorporated with a carrier 16 supporting the planetary gear 17 is supported freely rotatably to the input shaft 12. A gear 25 of a steering ratio control motor 26 is meshed with the gear 20. The steering angle ratio control motor 26 is controlled in accordance with an electronic control device 27. When the gear 25 of the steering angle ratio motor 26 can be freely rotated, the sun gear 14 rotated by the input shaft 20, and the carrier 16 integrally incorporated with the gear 20 which is rotated by gears 7, 9, a counter shaft 13, and a gear 19, are rotated at the same speed and in the same direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a steering angle ratio control mechanism for a four-wheel steering vehicle.

[Prior Art] In a four-wheel steering vehicle disclosed in Japanese Patent Application Laid-Open No. 57-11173, the rear wheels are steered in the opposite phase to the front wheels when driving at low speeds to improve the turning ability of the vehicle and to improve the turning ability of the vehicle while driving at high speeds. The wheels are steered in the same phase as the front wheels to improve steering stability. The steering angle ratio control mechanism disclosed in Japanese Patent Application Laid-open No. 59-81272 and Japanese Utility Model Application Publication No. 60-148170 uses a planetary gear system and rotates the third shaft with an electric motor to adjust the front wheel steering angle and vehicle speed. The steering direction and steering angle of the rear wheels are adjusted accordingly. However, since the third axle is not mechanically connected to either the front or rear axle, if the electric motor breaks down, the rear wheels cannot be steered, which poses a safety problem.

[Problem to be Solved by the Invention 1] In view of the above-mentioned problems, an object of the present invention is to change the rear wheel steering angle ratio according to the vehicle speed, improve maneuverability and stability, and
An object of the present invention is to provide a steering angle ratio control tIa mechanism in which a steering operation of a rear wheel is mechanically and safely maintained even if a steering angle ratio control motor breaks down.

[Means for solving the problem] In order to achieve the above object, the configuration of the present invention is such that the input shaft of the pinion that meshes with the rack rod of the front wheel and the output shaft of the pinion that meshes with the rack rod of the rear wheel are connected to the planetary gear H. A gear for supporting a carrier of a 31 gear device is rotatably supported on an input shaft, and a gear for a subshaft that rotates in conjunction with the input shaft and a gear for a steering angle ratio control motor are connected to each other through a gear. It is a combination of.

[Operation] When the handlebar 1 is turned to the right, for example, the rack rod 3 moves to the right, and the front wheel 4 is deflected to the right.

At the same time, the input shaft 6.12 of the pinion 5 meshing with the rack rod 3 rotates, causing the sun gear 14 of the TI star gearing 40 to rotate.
The planetary teeth 1117 that mesh with this, the internal teeth that mesh with this (# wheel 15, and the output shaft 22 that supports this are rotated in the same direction,
The rack rod 23 moves to the left, and the rear wheel 24 is deflected to the left (in the opposite phase to the front wheel 4). In this way, the ability to turn around at low speeds is improved.

5! ! A gear 20 formed integrally with the carrier 16 of the star tooth 1i17 and supported in an idling manner on the input shaft 12 has a steering angle ratio l1111111 of the motor 26, which is controlled by an electronic control device 27 according to the vehicle speed and the front wheel steering angle. The gears 25 are engaged, and the rotation ratio (steering angle ratio) and rotation direction of the output shaft 22 to the input shaft 12 are controlled.

If the steering angle ratio 11111 motor 26 fails, the gear 19 of the countershaft 13, which has relatively low rigidity and is rotated in the opposite direction together with the input shaft 12 via the gear 7.9, meshes with the gear 20, and the output The shaft 22 is rotated in the same direction as the input shaft 12 at the circumferential speed.

[Embodiments of the Invention] FIG. 1 is a plan view showing a schematic configuration of a four-wheel steered vehicle equipped with a steering angle ratio control column Δ according to the present invention.

The knuckle arms 32 that support the left and right front wheels 4 are supported by the vehicle body by vertical support shafts 31, and are interlocked and connected to each other by rack rods 3. The pinion 2 of the steering shaft 36 of the handle 1 is engaged with a rack formed on the lower surface of the rack rod 3. Similarly, the shaft 6 of the pinion 5 that meshes with the rack of the rack rod 3 is connected to an input shaft 12 in the longitudinal direction by a universal joint 10. Further, a shaft 8 of a gear 9 that meshes with the tooth width 7 of the shaft 6 is supported on the vehicle body side, and this shaft 8 is connected by a universal joint 11 to a countershaft 13 in the longitudinal direction having relatively low rigidity.

The input shaft 12 can rotate relative to the output shaft 22 by a bearing 38.
is connected with. The pinion 21 of the output shaft 22 is engaged with a rack formed on the upper surface of the rack rod 23. Each knuckle arm 34 supporting the left and right rear wheels 24 is supported by the vehicle body by a vertical support shaft 33, and is interlocked and connected by a rack rod 23.

The steering angle ratio control mechanism A includes a Ti W m II device M40. That is, sun gear 14 coupled to input shaft 12
A planetary gear 17 is meshed between the internal gear 15 and the internal gear 15 coupled to the output shaft 22. A gear 20 that is integral with the carrier 16 that supports the planetary gear 17 is supported by the input shaft 12 so as to be freely rotatable. Teeth 1 connected to the countershaft 13 on the gear 20!
19 are engaged.

Furthermore, a gear 25 of a steering angle ratio control motor 26 is meshed with the gear 20 .

The steering angle ratio control motor 26 is controlled by the output of the electronic control 1!11!27. Electronic ll1IJtld device! For example, a signal from a front wheel steering angle sensor 28 disposed on the steering shaft 36 and a signal from a vehicle speed sensor 29 disposed opposite to the output shaft of the transmission are added to 27, and based on these signals, An output signal for obtaining a steering angle ratio set in advance in memory is applied to the steering angle ratio control motor 2G.

When the gear 25 of the steering angle ratio control motor 26 can rotate freely, the sun gear 14 rotated by the input shaft 12 and the peak 11
7.9. Gear 20 rotated via countershaft 13 and gear 19
and the integrated carrier 16.

The gear ratio of each gear is set so that each gear rotates at the same speed and in the same direction.

When the steering wheel 1 is turned to the right, for example, the front wheel 4 is deflected to the right. At the same time, the input shaft 12 which receives the rotation of the pinion 5 that meshes with the rack of the rack rod 3, the carrier 16 integrated with the gear 20a which receives m117.9, countershaft 13, l11119 (7) times, and the planetary gear 17 The output shaft 22 of the internal gear 15, which receives the rotation of the sun gear 14, rotates integrally at the same speed and in the same direction. Therefore, the rack rod 23 moves to the left, and the rear wheels 24 are deflected to the opposite phase (to the front wheels 4), thereby improving the ability to turn around at low speeds. At this time, since the input shaft 12 and the output shaft 22 are rotated in the same direction and at the same speed, the steering angle ratio is
The rear wheel steering angle relative to the front wheel steering angle is determined by the gear ratio of 1 and the lever ratio of the rear wheel knuckle arm 34, and the rear wheel steering angle with respect to the front wheel steering angle is represented by a line in FIG.

On the other hand, when a signal for obtaining a predetermined steering angle ratio is applied from the electronic control device 27 to the steering angle ratio sub motor 26 based on the signals from the front wheel steering angle sensor 28 and the vehicle speed sensor 29, the gear 25 is driven. The rotation of the carrier 16 integrated with the gear 20 is controlled in a range from 0 to the circumferential speed of the sun gear 14.

For example, if the carrier 16 is fixed by applying a brake to the steering angle ratio control motor 26, the internal gear 15 rotates in the opposite direction to the rotation of the sun gear 14. At this time, the rear wheels 24 are steered in the same phase as the front wheels 4, as shown by taa in FIG. 3, and the steering stability at high speeds is improved. At this time, the countershaft 13 is twisted to absorb the difference in rotation between the gears 9 and 19.

Further, when the carrier 16 integrated with the gear 20 is slowly rotated clockwise by the steering angle ratio control motor 26 (FIG. 2), the rotation direction of the sun gear 14 and the internal gear 15 is the same, but the internal gear 15 is decelerated more than the sun gear 14, and the steering angle ratio becomes smaller.

If the rotation speed of the steering angle ratio control motor 26 is controlled while turning the steering wheel 1 in one direction from the neutral position, the la
As shown in C, when the front wheel steering angle is small, the rear wheel 24 is replaced by the front wheel 4.
The rear wheels 24 can also be steered in the same phase as the front wheels 4, and when the predetermined value is exceeded, the rear wheels 24 can be steered in the opposite phase to the front wheels 4.

FIG. 4 is a flowchart of a program for controlling the above-mentioned steering angle ratio control motor 26 by the electronic control unit 27. This program is repeatedly executed at predetermined intervals. The program starts with pll, and the front wheel steering angle sensor 28 with p12.
Based on the signal from the vehicle speed sensor 29 and the signal from the vehicle speed sensor 29, the front wheel steering angle θ
and read the vehicle speed V. In p13, it is determined whether or not the vehicle speed V is smaller than the reference value ■0. If the vehicle speed V is larger than the reference value VO, the process proceeds to p15. If the vehicle speed ■ is smaller than the reference value ■0, the front wheels are It is determined whether the steering angle θ is smaller than a reference value θO. If the front wheel steering angle θ is larger than the reference value θ0, return to p14, and if the front wheel steering angle θ is smaller than the reference value θ0, find the rear wheel steering angle command value X corresponding to the front wheel steering angle from the memory in p15. , is output to the steering angle ratio control motor 26. The planetary gear device 40 is driven by the steering angle ratio IIJII motor 26 so that the rear wheel steering angle becomes the command value X,
Ends on p16.

When the rear wheels are steered in the same phase as the front wheels when driving at high speed, the steering wheel 1 feels heavy due to twisting of the countershaft 13, but this helps to suppress the steering wheel 10 from being blurred and improves steering stability.

If the steering angle ratio control motor 26 fails, the steering angle ratio control motor 26 can rotate freely, so the action of the countershaft 13 described above causes the thick gear 14 and the internal gear 15 to operate at the same speed and in the same direction. Rotate to . The input shaft 12 and the output shaft 22 rotate at the same speed and in the same direction, and the rear wheels are steered in the opposite phase to the front wheels. This mechanical connection allows stable maneuvering to continue.

Note that when a hydraulic power steering mechanism is attached to the rear wheels, even if the subshaft 13 is twisted, the load on the rear wheel steering mechanism t1 is transferred to the subshaft 1.
3, there is no time delay in steering operations between the front and rear wheels.

Further, in the above embodiment, the subshaft 13 is a hollow shaft,
By inserting and supporting the input shaft 12 inside this, space can be saved.

[Effects of the Invention] As described above, the present invention connects the input shaft of the pinion that meshes with the rack rod of the front wheel and the output shaft of the pinion that meshes with the rack rod of the rear wheel through a planetary gear system, and
A gear that supports the carrier of the rear gear device is rotatably supported on the input shaft, and the gear that rotates in conjunction with the input shaft and the gear of the steering angle ratio control motor are meshed with the gear, so that the rear wheel steering mechanism can be realized. The output shaft that drives the front wheel is driven by the input shaft rotated in conjunction with front wheel steering at the required steering angle ratio through eight planetary gears, and the subshaft that is always rotationally interlocked with the input shaft rotates the planetary gears. Since the carry S- is mechanically connected to the output shaft, stable function as a four-wheel steered vehicle is maintained even if the steering angle ratio control motor that controls the rotation of the gear rear fails.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a schematic configuration of a four-wheel steering vehicle equipped with a steering angle ratio control mechanism according to the present invention. Figure 2 shows the same organization's meteorite m.
FIG. 3 is a diagram illustrating the operation of the steering angle ratio control m+ mechanism, and FIG. 4 is a flowchart of a program for controlling the steering angle ratio control motor. 3.23 Nirakkurod 5.21: Pinion 12: Input shaft 13: Subshaft 16: Carrier 20: Gear 22:
Output shaft 26: Steering angle ratio control motor 27: Electronic control device 40: Planetary gear device patent applicant ISUI Jidosha Co., Ltd.

Claims (1)

[Claims] The pinion input shaft that meshes with the front wheel rack rod and the pinion output shaft that meshes with the rear wheel rack rod are connected via a planetary gear system, allowing the gear that supports the carrier of the planetary gear system to freely rotate around the input shaft. A steering angle ratio control mechanism characterized in that a gear of a subshaft supported and rotated in conjunction with the input shaft is meshed with a gear of a steering angle ratio control motor.