JPS6234228B2 - - Google Patents

Description

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

The present applicant has previously provided a vehicle steering system in which front wheels and rear wheels are steered by steering operation of a steering wheel. Specifically, the steering device is configured to steer the rear wheels in the same direction as the front wheels when a small steering angle operation of the steered wheels is generally performed while the vehicle is running at high speed, and when the vehicle is running at low speed. In a large steering angle operation of the steered wheels, the rear wheels are steered in the opposite direction to the front wheels, or the steered angle of the rear wheels is returned to zero. This eliminates the difference in the generation time of lateral forces between the front and rear wheels and the discrepancy between the vehicle direction and the tangential direction of the turning trajectory, improves maneuverability during high-speed driving, and improves steering wheel control during low-speed driving. The performance can be made to be good or comparable to ordinary vehicles.

By the way, the rear wheels are suspended on the vehicle body by a suspension mechanism consisting of a shock absorber, a lower arm, etc. so as to be able to swing vertically, but depending on the desired suspension characteristics of the suspension mechanism, it may be necessary to lengthen the lower arm. In such a case, in a device that steers the rear wheels together with the front wheels as described above, the left and right tie rods for steering the rear wheels will also be long, so it is required that the rear wheel steering means have a compact structure. .

The present invention has been made in response to the above-mentioned demands, and an object of the present invention is to enable the rear wheels to be steered together with the front wheels by the steering operation of the steered wheels, and to turn the rear wheels to the front wheels when the steered wheels are operated at a small steering angle. In a vehicle steering system, the rear wheels can be steered in the same direction as the front wheels, and when the steered wheels are operated at a large steering angle, the rear wheels can be steered in the opposite direction to the front wheels, or the rear wheels can be steered in the same direction as the front wheels. To provide a steering device for a vehicle that can cope with long lower arms and left and right tie rods for steering rear wheels by making the steering means simple and compact.

In order to achieve the above objects, the present invention provides an input shaft that rotates the rear wheel steering means in conjunction with the steered wheels, and a crank member that is coupled to the input shaft and has a length in the outer diameter direction of the shaft. The present invention is characterized in that separate right and left rear wheel steering tie rods are connected to the crank member, respectively.

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 device according to the present invention. A steering shaft 11 of a steering wheel 10 operated by a driving vehicle is a gearbox 1.
The steering wheel 10 is connected to a direction changing means installed inside the steering wheel 2, and the steering rotation of the steering wheel 10 is controlled by the direction changing means, which is a rack-and-pinion type, for example, and the right and left front wheel steering tie rods 14, 14 are connected to each other via a connecting rod 13. This is converted into movement in the width direction of the vehicle. The tie rod 1
The outer ends of the tie rods 14 and 14 are connected to knuckle arms 16 and 16 that support the front wheels 15 and 15 and are rotatable in the left and right directions, and the front wheels 15 and 15 are steered by the above movement of the tie rods 14 and 14. The wheels 10 are steered in the steering direction. The configuration of the front wheel steering means described above is the same as the known one, and the gearbox 12
By attaching a power steering device to the steering wheel 10
The steering operation is assisted by the power steering device.

A connecting shaft 17 is connected to the gearbox 12 via an operating force transmission mechanism such as a rack and pinion, bevel gear, or worm gear that corresponds to the internal mechanism of the gearbox 12, and the connecting shaft 17 has an operating shaft extending in the longitudinal direction of the vehicle body. The front ends of 18 are connected by a universal joint 19. An input shaft 21 shown in FIG. 3 is connected to the rear end of the operating shaft 18 by a universal joint 20, and the input shaft 21 is rotatably supported by a bearing bracket 22 attached to the vehicle body. When the steered wheel 10 is rotated, the operating shaft 18 is rotated via the internal mechanism of the gearbox 12 and the connecting shaft 17, and the input shaft 21 is rotated in conjunction with the steered wheel 10. A crank member 23 is integrally connected to the rear end of the input shaft 21 protruding from the rear end surface of the bracket 22, and the crank member 23 has a length in the direction of the outer diameter of the input shaft 21. These input shafts 21
and a linear crank member 23 whose one end is connected to the input shaft 21 and rotates in a vertical plane about the one end, constitutes a crank mechanism type rear wheel steering means 24, which is used when the vehicle is traveling straight, that is, when the vehicle is being steered. When the wheel 10 is in the neutral position, the crank member 23 is in a vertical position as shown in FIG.

The left and right rear wheels 25, 25 are supported by knuckle arms 26, 26 that are rotatable left and right, and the knuckle arms 26 include a shock absorber 27 whose upper end is connected to the vehicle body;
and the inner end thereof is suspended by a lower arm 28 which is pivotally connected to the vehicle body in a vertically swingable manner, and the present invention has the desired suspension characteristics for a rear wheel suspension mechanism consisting of the shock absorber 27, the lower arm 28, etc. The lower arm 28 of a vehicle equipped with such a device is long.

The outer ends of left and right tie rods 29, 29 for steering the rear wheels are connected to the left and right knuckle arms 26, 26, and when the tie rods 29, 29 move in the width direction of the vehicle body due to tensile force and pressing force, the rear wheels are steered. 2
5 is steered by the left and right rotation of the knuckle arm 26.

The inner ends of the left and right rear wheel steering tie rods 29, 29 are connected to the crank member 23, and the connection is made at the other end of the crank member 23, which is spaced apart from one end to which the input shaft 21 is connected in the shaft outer radial direction. .
If the lower arm 28 is set to be long as described above, the tie rod 29 will also be lengthened, but since the crank member 23 serving as the output member of the rear wheel steering means 24 to which the tie rod 29 is connected may be a linear rod member, The length of the rear wheel steering means 24 in the vehicle width direction is small, so even if the tie rod 29 whose length direction is in the vehicle width direction becomes longer, the vehicle width becomes larger due to the rear wheel steering means 24. Never. In particular, as shown in Figure 2, the left and right tie rods 2
By commonly connecting the inner ends of the rear wheel steering means 24 to the same position of the crank member 23 by means of a connecting pin 30 implanted in the crank member 23 so as to protrude toward the rear of the vehicle body, the rear wheel steering means 24 can be rotated in the vehicle width direction. The size can be further reduced. Further, as the crank member 25 rotates, the connecting portion between the crank member 25 and the left and right tie rods 29, 29, ie, the connecting pin 30, moves up and down, but the left and right tie rods 29, 29 are separate bodies as described above. Therefore, they can each swing vertically separately to change their axial directions, and thus can move in the width direction of the vehicle body in response to the vertical movement of the connecting pin 30.

Furthermore, in this embodiment, the rear wheels 25, 2
Tie rods 29, 29 due to steering of 5
In consideration of the change in the axial direction due to the back and forth rocking of the tie rods 29, 29 and the connecting pin 30, a spherical bearing 31 is used as shown in FIG.

When the steering wheel 10 is steered to the left, the front wheels 15 are steered to the left, and the crank member 23 rotates together with the input shaft 21 as shown by the chain line in FIG. to steer. When the steering wheels 10 are steered to the right, the steering direction of the front wheels 15 and the rotation direction of the crank member 23 are reversed.
The basic operation is the same. If a power steering device is attached to the gearbox 12, the rear wheels will be steered with the power assistance of the power steering device, and the front wheel power steering device is different from the power steering device for the rear wheels. It is also possible to equip the vehicle with a steering device. As shown in Fig. 2, when the crank member 23 is rotated by an angle α°, the horizontal movement stroke of the tie rod 29 is defined as x, and Fig. 4 is a graph showing α° as the horizontal axis and x as the vertical axis. ing.

x changes according to the sine curve value of α゜, x reaches its maximum value when α゜ is 90゜, returns to zero when α゜ reaches 180゜, and when α゜ exceeds 180゜, x
is a value with sign opposite to the above, and this value is α゜
It reaches its maximum at 270°. Therefore α゜ is 0゜ and 180
If the angle is between
Although it is steered in the same direction as 5, α° is 180°.
If the angle is between 360°, the rear wheels 25 are steered in the opposite direction to the front wheels 15. The above explanation ignores the height component of the length of the tie rod 29, which changes as the connecting pin 30 moves up and down, but the length of the tie rod 29 is long as described above, and is extremely large compared to the rotation radius of the connecting pin 30, and there is no problem in considering the horizontal length component of the tie rod 29 in the x direction as the actual length dimension of the tie rod 29. There will be no difference.

A transmission mechanism such as a gear mechanism is interposed in the rear wheel turning operation force transmission path from the steered wheel 10 to the crank member 23, and the speed change rate of the transmission mechanism is appropriately set to control the crank relative to the rotation angle of the steered wheel 10. By arbitrarily determining the rotation angle of the member 23, the front wheels 15 and the rear wheels 25 are steered in the same direction at a small steering angle of the steered wheels 10, and the rear wheels 25 are steered in the opposite direction to the front wheels 15 at a large steering angle. At a small steering angle of the steered wheels 10, the front wheels 15 and rear wheels 25 are steered in the same direction, and at a large steering angle, the steering angle of the rear wheels 25 is made zero or close to zero. can.

The magnitude of the steering angle of the rear wheels 25 is determined by the crank member 23.
The ratio of the rear wheel steering angle to the front wheel steering angle is related to the separation distance between both ends of the input shaft 21 and the connecting pin 30, and is considered desirable for a vehicle to which the device according to the present invention is applied. The separation distance is determined accordingly.

As is clear from the above description, according to the present invention,
The rear wheel steering means, which is composed of the input shaft and the crank member and is compact in the width direction of the vehicle body, allows the left and right rear wheel steering tie rods to be moved in the width direction of the vehicle body, so that the length of the tie rods relative to the vehicle body dimensions can be reduced. The ratio can be increased, and the lower arm that suspends the rear wheel can be made longer. Further, by commonly connecting the right and left rear wheel steering tie rods to the crank member, the rear wheel steering means can be made more compact.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a perspective view showing the general basic structure of a vehicle; FIG. 2 is a view taken in the direction of arrow 2 in FIG. 1; and FIG. The 3-line sectional view and FIG. 4 are graphs showing the movement stroke of the rear wheel steering tie rod with respect to the rotation angle of the crank member. In the drawing, 10 is a steering wheel, 15 is a front wheel, 21 is an input shaft, 23 is a crank member, 25 is a rear wheel, 29
is a tie rod for rear wheel steering.

Claims (1)

[Scope of Claims] 1. In a vehicle steering device in which front wheels and rear wheels are steered by steering operation of a steered wheel, an input shaft that rotates in conjunction with the steered wheels has a length in the direction of the outer diameter of the shaft. What is claimed is: 1. A steering system for a vehicle, characterized in that a crank member having a diameter is coupled to the crank member, and separate right and left rear wheel steering tie rods are respectively connected to the crank member. 2. The vehicle steering device according to claim 1, wherein each of the left and right rear wheel steering tie rods is commonly connected to the same location of the crank member.