JPH0352381B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steering system for a vehicle that steers both the front wheels and the rear wheels by the steering operation of the steering wheels, and particularly, the present invention relates to a steering system for a vehicle that steers both the front wheels and the rear wheels by the steering operation of the steering wheels. The present invention relates to an applicable vehicle steering device.

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 a conversion unit that is connected to the rear end of the actuating member to move a tie rod for steering the rear wheels left and right. A steering system for a vehicle that simultaneously steers the front wheels and rear wheels by operating the steering wheels (patent application 1983).
-47743 (see JP-A-58-164478)) was previously provided by the present applicant.

Such a steering device extracts the rotation necessary for rear wheel steering from the front wheel steering mechanism as the rotation of the offset arm, has an actuating member that moves back and forth in conjunction with the arm, and converts the back and forth movement of the actuating member into left and right movement. The steering angle function is configured to generate a desired steering angle function for the rear wheels via a conversion mechanism that performs conversion.

This allows the rear wheels to be steered in the same direction as the front wheels by operating a small steering angle of the steering wheel, and can also be steered in the opposite direction by operating a large steering angle, thus improving maneuverability at high speeds. In addition, when making a U-turn or entering/exiting a parking lot, the steering angle is increased to obtain a small turning radius, which improves maneuverability of the vehicle.

However, in both devices, the front wheel steering gear was of the rack-and-pinion type.

A system in which the offset arm is directly attached to the steering shaft has also been proposed, but with this, it is not possible to arbitrarily set the rotation ratio of the offset arm.

The present invention is not limited to the rack-and-pinion type, but can be applied to any type of front wheel steering gear, such as a recirculating ball type, to generate a steering angle function similar to that described above in the rear wheels, and to rotate the offset arm. The ratio was made to be able to be set arbitrarily, and the purpose was to achieve the desired effect by simply adding a simple structure to the front wheel steering gear box, such as a recirculating ball type gearbox. To provide a steering device for a vehicle which can freely set the rotation ratio without uniformly rotating an offset arm integrally with a steering shaft.

In order to achieve such an object, the present invention provides a steering shaft having a fixed steering wheel, an offset arm that rotates in conjunction with the steering shaft, and an operating member whose front end is connected to the arm and is movable back and forth. and a conversion mechanism connected to the rear end of the actuating member to move a rear wheel steering tie rod left and right, in a vehicle steering device that steers both the front wheels and the rear wheels by steering operation of the steered wheels, A front wheel steering gear is fixed on the steering shaft, and a rear wheel steering gear is fixed on the steering shaft at a position different from the front wheel steering gear, and the gear is engaged with the front wheel steering gear. A Pitman shaft for steering the front wheels is fixed to the first gear, and a rotating shaft of the second gear meshing with the gear for steering the rear wheels is fixed to the offset arm.

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 a bottom view of the inside of the gearbox, and Fig. 3 is a main part of the gearbox shown in Fig. 2. FIG. 3 is a left side view in three directions of arrows.

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 steering gear box 20 via a universal joint 3, and the outermost tip of the steering shaft 2 has a As is known, a ball nut 22 is fitted through a worm, a ball circuit, and a ball, and a rack tooth pattern 23 is formed on the left side of the outer periphery of the ball nut 22.

A sector gear 24 meshes with the rack teeth 23 of the ball nut 22, a shaft 25 of the gear 24 constitutes a Pittman shaft, and
The base of the pitman 4 is fixed to the lower end of a pitman shaft 25 that extends downwardly from the pitman 4.

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 steered wheels 1. That is, the rotation of the steering shaft 2 causes the ball nut 22 to move back and forth through the worm, ball circuit, and ball.
The pitman arm 4, which is integrated with the sector gear 24 that meshes with the rack teeth 23, 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 arm 10,
10 rotates in the left-right direction, and the front wheels 12, 12 are steered.

A first bevel gear 26 is fixedly installed on the outer periphery of the steering shaft 2 in front of the ball nut 22 within the recirculating ball type gear box 20.
A second bevel gear 27 is meshed with this 26.

That is, as shown in the figure, these pair of bevel gears 26,
27 are orthogonally engaged with each other, a rotating shaft 28 of the second bevel gear 27 is provided to project downwardly below the case lower wall 21 of the gear box 20, and the base of an offset arm 29 is fixedly integrated with the lower end of the shaft 28.

At the tip of the offset arm 29, there is a push-pull link 30 which is an operating member and is long in the front-rear direction.
The tips of the push-pull link 30 are pivotally connected to each other, and one end of a swing link 31 having an L-shape in plan is pivotally connected to the rear end of the push-pull link 30.

The base of the swing link 31 is supported by a shaft 33 vertically disposed on a bracket 32, and the other end of the link 31 connects and supports left and right tie rods 13, 13.

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

In addition, gearbox 20 and both brackets 8, 32
is fixed to the vehicle body.

When the steering wheel 1 is steered, the second bevel gear 27 that meshes orthogonally with the first bevel gear 26 fixed to the steering shaft 2 rotates to either the left or the right, that is, the offset arm 29 integrated with this 27 rotates. The rotation is output.

The rotation extracted from the recirculating ball type front wheel steering gear box 20 causes one end of the swing link 31 to swing back and forth through the back and forth and left and right swings of the push pull link 30. Then, the other end of the swing link 31 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.

At this time, the rear wheels 16 are controlled with a predetermined steering angle function by the rotation of the offset arm 29, that is, by a small steering angle operation of the steered wheels 1, the rear wheels 16 are steered in the same direction as the front wheels 12; When operating a large steering angle, the steering is turned in the opposite direction to improve maneuverability while driving at high speeds, and when making U-turns or maneuvering in and out of parking lots, the steering angle is increased to achieve a small turning radius. This improves the maneuverability of the vehicle.

As described above, even with the recirculating ball type front wheel steering gearbox 20, it is possible to generate a predetermined steering angle function necessary for steering the rear wheels 16.
The above can be achieved by simply adding a simple structure consisting of 7.

Furthermore, since the steering shaft 2 is configured to indirectly output rotation to the offset arm 29 via the gear mechanisms 26 and 27, the rotation ratio of the offset arm 29 with respect to the steering shaft 2 is determined by the pair of gear mechanisms 26 and 2.
It can be set arbitrarily by changing the gear ratio of 7.

Furthermore, the above configuration can of course be implemented with any type of front wheel steering gear, such as a rack and pinion type in addition to the recirculating ball type.

In the embodiment, the new gear mechanisms 26 and 27 are orthogonally meshed, but the meshing angle can be arbitrarily set variously. Also, although the push-pull link 30 is used as the operating member, a cable or chain may be used instead. The converting mechanism is not limited to the planar L-shaped swing arm 31, and of course, other configurations may be adopted as appropriate.

As is clear from the above description, according to the present invention, even if the vehicle is equipped with a gearbox for steering the front wheels, it is possible to generate a predetermined steering angle function necessary for steering the rear wheels, and furthermore, even if the vehicle is equipped with a gearbox for steering the front wheels, it is possible to generate a predetermined steering angle function necessary for steering the rear wheels. It is only necessary to add a simple structure to the offset arm, and it has various features such as being able to freely set the rotation ratio of the offset arm.

[Brief explanation of drawings]

The drawings show an 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, FIG. 2 is a bottom view of the inside of a gearbox, and FIG. FIG. 3 is a view taken in the three directions of the arrows in FIG. 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 front wheel steering gear box, 26 and 27 are gear mechanisms, 29 is an offset arm, 30 is an operating member, and 31 is a conversion mechanism.

Claims (1)

[Claims] 1. A steering shaft to which a steering wheel is fixedly attached, an offset arm that rotates in conjunction with the steering shaft, an actuating member whose front end is connected to the arm and is movable back and forth, and connected to the rear end of the actuating member. and a conversion mechanism for moving a tie rod for rear wheel steering from side to side, and in which the rear wheels are steered along with the front wheels by steering operation of the steered wheels. At the same time, a rear steering gear is fixedly installed on the steering shaft at a position different from the front wheel steering gear, and a first gear meshing with the front wheel steering gear is provided with a pit man for front wheel steering. A steering device for a vehicle, characterized in that a shaft is fixedly installed, and a rotating shaft of a second gear that meshes with the rear wheel steering gear is fixed to the offset arm.