JPS6318545B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steering system for a vehicle, particularly a four-wheeled vehicle.

More specifically, the present invention relates to a vehicle steering system that controls the steering angle ratio between front wheels and rear wheels in accordance with vehicle speed, facilitates steering of a four-wheeled vehicle, and significantly reduces the minimum turning radius of the vehicle.

The present applicant previously provided a vehicle steering system in which the front wheels and rear wheels can be simultaneously steered by operating the steering wheels in Japanese Patent Application No. 118698/1983. did.

Incidentally, Japanese Patent Application Laid-Open No. 55-91459 discloses that the rear wheels are steered in the same phase as the front wheels or in the opposite phase depending on the vehicle speed.

The present invention further improves such a steering system so that the steering angle ratio between the front wheels and the rear wheels can be controlled according to the vehicle speed. At times, the rear wheels are steered in the same direction as the front wheels, and when driving at low speeds, the rear wheels are steered in the opposite direction to the front wheels, thereby improving maneuverability at high speeds and maneuverability of the steering wheels at low speeds. To provide a vehicle steering device that improves steering performance.

In order to achieve the above object, the present invention connects a swing shaft via a joint to an input shaft that rotates in conjunction with the steering wheels, and connects and supports left and right rear wheel steering tie rods to the swing shaft. Loosely fitting a joint member and connecting an arm member to this joint member,
This arm member is driven and controlled according to the vehicle speed.
A drive device that makes the swing angle of the swing shaft variable with respect to the input shaft is connected.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

Fig. 1 is a perspective view showing the general basic structure of a four-wheeled vehicle equipped with a steering system according to the present invention, Fig. 2 is an enlarged perspective view of the main part of Fig. 1, and Fig. 3 a, b, and c are FIG. 2 is a schematic front view showing the operating principle of the present steering device.

In Fig. 1, reference numeral 1 denotes a steering wheel operated by the driver, and its steering shaft 2 is connected to a direction change means built into a gearbox 3, and the steering rotation of the steering wheel 1 is performed, for example, by a rack-and-pinion system. The direction changing means converts the movement of the left and right front wheel steering tie rods 5, 5 in the width direction of the vehicle body via the connecting rod 4. The outer ends of both tie rods 5, 5 are connected to knuckle arms 7, 7 which support front wheels 6, 6 and are rotatable in the left and right direction.
The front wheels 6, 6 are steered in the steering direction of the steering wheel 1 by the above-mentioned movement of the steering wheel 5.

The configuration of the front wheel steering means described above is the same as the known one, and by attaching a power steering device to the gearbox 3, the steering operation of the steered wheels 1 is assisted by the power steering device.

A connecting shaft 8 is connected to the internal mechanism of the gearbox 3 via an operating force transmission means suitable for the mechanism such as a rack and pinion, a bevel gear, a worm gear, etc., and an operating shaft 9 extending in the longitudinal direction of the vehicle body is connected to the connecting shaft 8. The front ends of the two are connected by a universal joint 10. A universal joint 1 is attached to the rear end of this operating shaft 9.
1 connects the front end of an input shaft 12, and the input shaft 12 is connected to a bearing bracket 1 attached to the vehicle body.
3 is rotatably supported. Furthermore, the input shaft 12
As shown in detail in FIG. 2, the front end of a swing shaft 14 is connected to the rear end of the swing shaft 14 through a pin joint 15 so as to be able to swing freely around the pin. A joint member 16 is loosely fitted to the joint member 16 so as to be relatively rotatable, and an arm member 17 whose length direction is in the width direction of the vehicle body is attached to the joint member 16 as shown in the figure.
The center part of is fixed.

The right end of the arm member 17 is connected to the vehicle body side via a link member 18 and a link bracket 19,
The left end is connected to the vehicle body via link members 20, 21 and a link bracket 22. A sector gear 24 is fitted onto the pivot shaft 23 of the link member 21, and the sector gear 24 is configured to rotate together with the link member 21.

The inner ends of rear wheel steering tie rods 25, 25 are connected to the left and right sides of the joint member 16 via ball joints 26, 26, and the outer ends of both tie rods 25, 25 are shown in FIG. Gotoku rear wheel 2
7, 27 are connected to knuckle arms 28, 28. And each nutkul arm 28
is suspended by a shock absorber 29 whose upper end is connected to the vehicle body, and lower arms 30, 30 whose inner ends are connected to the vehicle body so as to be vertically swingable.

On the other hand, a motor 31 is disposed on the vehicle body side of the left end outer extension of the arm member 17, an output shaft 32 of the motor 31 constitutes a worm gear 32a, and the worm gear 32a and the sector gear 24 mesh with each other as shown in the figure. ing.

By the way, a computer 33 is installed in the vehicle, and the computer 33 receives signals from a vehicle speed sensor 34 that detects the vehicle speed and a position sensor 35 that detects the rotational position of the link member 21, and generates appropriate control signals according to the vehicle speed. is sent to the motor 31 to control its rotation.

When the pivot point p of the joint member 16 coincides with the center o of the input shaft 12 as schematically shown in FIG. 3a, the input shaft 12 and the swing shaft 14 rotate concentrically. Therefore, at this time, the joint member 16 does not swing from side to side, and this joint member 16
Tie rods 25, 2 are formed by connecting their inner ends to
5 is stationary, and at this time, only the front wheels 6, 6 are steered, and the rear wheels 27, 27 are not steered at all, as in the conventional vehicle.

By the way, when the vehicle is traveling at a low speed where the vehicle speed is less than a set value, the computer 33 receives a signal from the vehicle speed sensor 34 and makes a judgment, and controls the rotation of the motor 31 according to the vehicle speed at that time. By controlling the rotation of the motor 31, the worm gear 32a formed on the output shaft 32 of the motor 31 is rotated by the sector gear 2 that meshes with the worm gear 32a.
4, and the link member 21, which rotates together with the sector gear 24, swings downward about the pivot 23, so that the left end of the arm member 17 is at the bottom as shown in FIG. 3b. tilt. Accordingly, the joint member 16 moves downward, and the swing shaft 14 swings downward about the pin of the horizontal pin joint 15. That is, due to the inclination of the arm member 17, the pivot point p is located below the shaft center o, and at this time, if the input shaft 12 is rotated, for example, counterclockwise by an angle θ, the tie rod 25,
25 moves to the right as shown by the broken line in Figure 3b,
The rear wheels 27, 27 are steered in the opposite direction to the front wheels 6, 6, and the front/rear wheel steering angle ratio at this time is continuously changed according to the vehicle speed. Furthermore, the angle θ of the input shaft 12
When the joint member 16 including the pivot point P and the arm member 17 rotate, the link member 18,
Move on the trajectory guided by pin joint 15
The pin is inclined by an angle θ from the horizontal position, and the swing shaft 14 swings around the pin so that its rear end follows the locus of the joint member 16, and the swing angle with respect to the input shaft 12 is changed. It is possible to change it. The rear end of the swing shaft 14 basically follows a spherical locus centered on its front end, and the joint member 16 is connected to the link members 18 and 20.
and passes along a trajectory guided by the arm member 17,
Differences in these trajectories are absorbed by the connecting portions of the link members 18, 20 to the main body, the connecting portions of the link members 18, 20 and the arm member 17, etc., and as a result, both move along substantially the same trajectory. .

If the vehicle speed then increases beyond the initial setting, the computer 33 causes the motor 31 to reverse, so that the arm member 17 is tilted in the opposite direction as shown in FIG. 3c, so that the pivot point p is If the input shaft 12 is located above the shaft center o and is rotated counterclockwise by an angle θ as described above, the tie rod 2
5 and 25 move to the left in the opposite direction to the above as shown by the broken line in FIG. is continuously changed according to the vehicle speed.

As described above, since the rear wheels are steered in the opposite direction to the front wheels when driving at low speeds, the turning radius of the vehicle can be significantly reduced, thereby improving the maneuverability of the steered wheels. .

In addition, when driving at high speeds, the rear wheels are steered in the same direction as the front wheels, so even immediately after the start of steering, the rear wheels generate cornering force at the same time as the front wheels, and the lateral acceleration of the vehicle reaches the intended value in a short time. It is possible to improve steering stability by improving steering response.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a perspective view showing the general basic structure of a four-wheeled vehicle equipped with a steering device according to the present invention, and FIG. 2 shows the main parts of FIG. 1. The enlarged perspective view and FIGS. 3A, 3B, and 3C are schematic front views showing the operating principle of the present steering system. In the drawing, 1 is a steering wheel, 5 is a front wheel steering tie rod, 6 is a front wheel, 9 is an operating shaft, 12 is an input shaft, 1
4 is a swing shaft, 16 is a joint member, 17 is an arm member, 24 is a sector gear, 25 is a tie rod for rear wheel steering, 27 is a rear wheel, 31 is a motor, 32a is a worm gear, 33 is a computer, 34 is a vehicle speed sensor, 35 is a position sensor.

Claims (1)

[Claims] 1. In a vehicle steering system in which the rear wheels are steered along with the front wheels by the steering operation of the steered wheels, a swing shaft is connected via a joint to an input shaft that rotates in conjunction with the steered wheels, and the swing shaft is A joint member that connects and supports left and right rear wheel steering tie rods is loosely fitted onto the shaft, and an arm member is connected to the joint member, and the arm member is driven and controlled according to the vehicle speed, and swings relative to the input shaft. A steering device for a vehicle, characterized in that it is connected to a drive device that makes the swing angle of a shaft variable.