JPH0352379B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle steering system that steers front wheels and rear wheels by steering operation of a steering wheel.

The present applicant has developed a system in which the steering ratio of the front and rear wheels is changed in proportion to the steering angle by first steering the steering wheels, and the front and rear wheels can be simultaneously steered in conjunction with each other. Steering system for vehicles (patent application 1983-)
No. 47743 (see JP-A-58-164478), etc.).

Such a steering device can steer the rear wheels in the same direction as the front wheels by operating a small steering angle of the steered wheels, and can also steer the rear wheels in the opposite direction by increasing the steering angle. In addition to improving maneuverability, the steering angle is increased during U-turns, entering/exiting operations in parking lots, etc. to obtain a small turning radius, resulting in good maneuverability of the vehicle.

However, if the front wheel steering gear is a rack-and-pinion type, it is easy to obtain a signal of the front wheel steering angle, but even if the front wheel steering gear is a recirculating ball type, The present invention has been devised to generate a steering angle function similar to that described above, and its purpose is to achieve the desired effect by simply adding a simple structure to the front wheel steering gearbox, etc. The object of the present invention is to provide a vehicle steering device that can be used as a steering device for a vehicle.

In order to achieve such an object, the present invention provides an offset arm that rotates in conjunction with a steering wheel, an actuating member whose front end is connected to the arm and is movable back and forth, and an actuating member that is connected to the rear end of the actuating member. , a vehicle steering system that includes a conversion mechanism that moves a rear wheel steering tie rod left and right, and that steers both the front wheels and the rear wheels by steering operation of the steered wheels. The offset arm is provided with an engaging element that engages with a cam groove formed in the cylindrical cam, and the cylindrical cam and the engaging element constitute a steering angle function generating device.

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, and FIG. 2 is a partially cutaway plan view of the inside of a gearbox.

The tip of the steering shaft 2 of the steering wheel 1 that is steered by the driver is incorporated into a recirculating ball-type front wheel turning gearbox 20 via a universal joint 3, and the tip of the steering shaft 2 is attached to the outer periphery of the tip of the steering shaft 2. is warm 21
is formed, and on the outer periphery of the worm 21 there is a ball nut 24 with a ball circuit 23 formed on the inner periphery.
As is known, they are fitted with balls 22 interposed therebetween.

A rack tooth pattern 25 is formed on the left side of the outer periphery of the ball nut 24, and a sector gear 26 meshes with this rack tooth pattern 25. A shaft 27 of this 26 constitutes a pit man shaft, and a pit man that projects downwardly from the gear box 20. The base of the Pittman arm 4 is fixed to the lower end of the shaft 27.

The right end of a connecting rod 5 is pivotally connected to the tip of the pitman arm 4, while the tip of an idler arm 6 is pivotally connected to the left end of the rod 5, and the idler shaft 7 at the base of the idler arm 6 is mounted on a bearing. It is supported by a bracket 8.

Tie rods 9, 9 are connected to the left and right ends of the connecting rod 5, knuckle arms 10, 10 are connected to the outer ends of the tie rods 9, 9, and the front wheels 12, 12 are connected to the knuckle arms 10, 1.
The vehicle is supported by axles 11, 11 that protrude outward from the vehicle.

The front wheels 12, 12 are steered by steering the steering wheel 1. That is, the rotation of the steering shaft 2 causes the ball nut 24 to move back and forth via the worm 21, balls 22, etc., and the ball circuit 23. The pitman arm 4, which is integrated with the sector gear 26 that meshes with the rack teeth 25, swings horizontally in the left-right direction, thereby causing the connecting rod 5 and both tie rods 9, 9 to move left and right, and the knuckle arms 10, 10 to rotate in the left-right direction. front wheel 1
2 and 12 are steered.

A rear wheel steering cam 30 is integrally provided on the steering shaft 2 within the recirculating ball type gear box 20.

The rear wheel steering cam 30 is a cylindrical cam, and is integrated in front of the worm 21 at the leading edge of the steering shaft 2, and a cam groove 31 is formed on the outer periphery of the cam 30 from the tip to the rear end for a little less than two circumferences. has been done.

The cam groove 31 is shown in a developed view in FIG.
Draw a trajectory that is symmetrical with the F-shaped point, that is, once cross the front and rear center line 30a of the cam 30 backwards from the groove tip 32 to the neutral point (center point of symmetry) 34.
3 is formed, and after 35 once crossing forward from the neutral point 34, a groove is formed to the rear end portion 36 of the groove.

A pin 41, which is an engager, is engaged with the cam groove 31, and the pin 41 is installed vertically upward from the tip of the crank arm 42, and is engaged with the neutral point 34 of the cam groove 31 from below in the initial setting. are doing. These rear wheel steering cam 30 and pin 41 constitute a steering angle function generating mechanism.

An offset shaft 43 is fixedly suspended from the base of a crank arm 42 having a pin 41 at its tip, and the offset shaft 43 is provided to protrude below the gear box 20.
The base of an offset arm 44 is fixedly integrated with the lower end of the shaft 43.

As a result, the pin 41 is attached to the offset arm 44 via the crank arm 42 and the offset shaft 43.
are integrated.

The tip of the push-pull link 50, which is an operating member and is long in the front-rear direction, is pivotally connected to the tip of the offset arm 44 that is integrated with the pin 41, and the rear end of the push-pull link 50 has a planar L-shape. One end of the swing link 51 is pivotally connected.

The base of the swing link 51 is supported by a shaft 53 vertically disposed on a bracket 52, and the other end of the link 51 connects and supports the left and right tie rods 13, 13.

Knuckle arms 14, 14 are connected to the outer ends of both tie rods 13, 13.
Rear wheels 16, 16 are supported by axles 15, 15 that protrude outward from wheels 4, 14.

In addition, gearbox 20 and both brackets 8, 52
is fixed to the vehicle body.

When the steering wheel 1 is steered, the rear wheel steering cam 30 located inside the gear box 20 and integrated with the steering shaft 2 rotates to either the left or right, and the pin guided in the cam groove 31 on the outer periphery of the cam 30 rotates. The rotation is output to the offset arm 44 which is integrated with the offset arm 41.

The rotation taken out from the recirculating ball type front wheel steering gear box 20 causes one end of the swing link 51 to swing back and forth through the back and forth and left and right swings of the push pull link 50. Then, the other end of the swing link 51 is caused to swing left and right, and the rear wheels 16, 16 are steered via tie rods 13, 13 and knuckle arms 14, 14.

That is, from the neutral point 34 of the cam groove 31 of the cam 30, the pin 41 is inserted into the groove 33, 35 beyond the center line 30a.
is engaged, the rear wheels 16 are steered in the same phase as the front wheels 12, and are engaged between both groove ends 32, 36 from the center line 30a with further rotation of the steering shaft 2. In this case, the wheels are steered to the opposite phase.

As described above, the rear wheels 16 are controlled with a predetermined steering angle function by the combined motion of the cam mechanisms 30, 41 and the offset arm 44, that is, by a small steering angle operation of the steered wheels 1, the rear wheels 16 are moved in the same direction as the front wheels 12. By steering the vehicle in the opposite direction when operating a large steering angle, it improves maneuverability at high speeds, and also increases the steering angle when making U-turns or maneuvering in and out of parking lots. Since a small turning radius is obtained, maneuverability of the vehicle is improved.

In the embodiment, the push-pull link 50 is used as the actuating member, but a cable, chain, etc. may be used in place of this, and the conversion mechanism is also an L-shaped swing arm 51 in plan view.
Of course, the present invention is not limited to this, and other configurations may be adopted as appropriate.

As is clear from the above description, according to the present invention, even in a vehicle equipped with a recirculating ball type front wheel steering gear box, a predetermined steering angle function necessary for rear wheel steering can be generated. Moreover, the above can be achieved by simply adding a simple structure inside the gearbox.

By the way, in the present invention, the ball nut 24 and the cam 3
0 are arranged in series, but it is also possible to arrange them in parallel by interposing another gear mechanism or the like.

[Brief explanation of drawings]

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 system according to the present invention, and FIG. 2 is a partially cutaway view of the inside of the gearbox. The plan view and FIG. 3 are developed views of the cam grooves. In the drawing, 1 is a steering wheel, 2 is a steering shaft, 12 is a front wheel, 13 is a tie rod for rear wheel steering, 16 is a rear wheel,
20 is a recirculating ball type front wheel steering gear box, 30 is a rear wheel steering cam, 31 is a cam groove, 41 is an engaging element, 44 is an offset arm, 5
0 is an operating member, and 51 is a conversion mechanism.

Claims (1)

[Claims] 1. An offset arm that rotates in conjunction with the steering wheel, an actuating member whose front end is connected to the arm and is movable back and forth, and an actuating member that is connected to the rear end of the actuating member and moves a rear wheel steering tie rod left and right. A steering system for a vehicle comprising a conversion mechanism and configured to steer both the front wheels and the rear wheels by steering operation of the steered wheels. A steering device for a vehicle, characterized in that an engaging element that engages with the offset arm is provided integrally with the offset arm, and the cylindrical cam and the engaging element constitute a steering angle function generating mechanism.