JPS6234230B2 - - Google Patents

Description

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

The present applicant has provided a steering device for a vehicle in which the front wheels and rear wheels can be steered by first steering the steering wheels. Specifically, this steering device steers the rear wheels in the same direction as the front wheels when a small steering angle operation of the steering wheel is generally performed while the vehicle is running at high speed, and when the steering wheel is turned in the same direction as the front wheels when the vehicle is running at low speed. In the steering angle operation, the rear wheels are steered in a direction opposite to the front wheels, or the steering angle of the rear wheels is returned to zero. This eliminates the difference in the generation time of lateral force between the front and rear wheels, eliminates the mismatch between the vehicle direction and the tangential direction of the turning trajectory, improves maneuverability during high-speed driving, and improves maneuverability during low-speed driving. The maneuverability of the steered wheels can be made good or comparable to that of a general vehicle in which only the front wheels are steered.

As an example of such a steering device, the applicant of the present invention proposed a rear wheel steering mechanism in Japanese Patent Application No. 71778/1983 by connecting left and right rear wheel steering tie rods with a connecting rod that is movable in the width direction of the vehicle body. A crank pin is connected eccentrically in the radial direction of the input shaft to the input shaft that rotates in conjunction with the steering wheel, and the crank pin and the connecting rod are connected by a connecting rod, so that the input shaft, the crank pin proposed a structure in which the connecting rod for steering the rear wheels is moved in the width direction of the vehicle body by the crank motion of a crank mechanism consisting of the connecting rod.

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 that they can swing vertically, and 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, the left and right tie rods for steering the rear wheels become long, and the opposing ends of the two tie rods become closer together, so the rear wheel steering means needs to have a compact structure. You are requested to do so.

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. This vehicle steering system has a compact structure for the steering means, especially a structure with a small size in the vehicle width direction, so that it can cope with the long lower arm and left and right tie rods for steering the rear wheels. It's there to provide.

In order to achieve the above object, the present invention includes an input shaft that rotates the rear wheel steering means in conjunction with the steered wheels and is supported by a stationary member, and an input shaft that is connected to the input shaft and that rotates in the direction of the outer diameter of the shaft. a crank member having a length of
It is characterized by connecting tie rods for steering left and right rear wheels to the link member.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a perspective view showing the basic structure of a four-wheeled vehicle equipped with a device according to a first embodiment of the present invention, in which a steering shaft 11 of a steering wheel 10 operated by a driver is housed in a gearbox 12. The steering wheel 10 is connected to a direction changing means, and the steering rotation of the steering wheel 10 is controlled by the direction changing means, for example, a rack and pinion type, via the connecting rod 13, to the right and left front wheel steering tie rods 1.
4 and 14 in the vehicle width direction. The outer ends of both tie rods 14, 14 are connected to the front wheels 15, 15.
The front wheels 15, 15 are connected to knuckle arms 16, 16 which support the wheels and are rotatable in left and right directions, and the front wheels 15, 15 are steered in the steering direction of the steered wheels 10 by the movement of the tie rods 14, 14. The configuration of the front wheel steering means described above is the same as a known one, and by attaching a power steering device to the gearbox 12, the steering operation of the steered wheels 10 is assisted by the power steering device.

A connecting shaft 17 is connected to the internal mechanism of the gearbox 12 via an operating force transmitting means suitable for the mechanism, such as a rack and pinion, a bevel gear, or a worm gear. The front ends 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, whose axial direction is in the longitudinal direction of the vehicle body, is mounted on a bearing that is a fixed member attached to the vehicle body. bracket 2
2 is rotatably supported. 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.

Input shaft 2 protruding from the rear end surface of the bracket 22
A crank member 23 is integrally connected to the rear end of the input shaft 21, and the crank member 23 has a length in the direction of the outer diameter of the input shaft 21, and rotates around the end connected to the input shaft 21. , and when the vehicle is traveling straight, that is, the steering wheel 10
When the crank member 23 is in the neutral position, the crank member 23 is in a vertical position as shown in FIG. A rearwardly projecting pin 24 is implanted at the end of the crank member 23 opposite to the end connected to the input shaft 21, and the pin 24 connects a plate-shaped link member 25 with a triangular back shape as shown in FIG. is connected to the crank member 23, and the link member 25 is rotatable in a vertical plane with respect to the pin 24, and when the crank member 23 is in the vertical position, the link member 25 is also in the vertical position. . One end of a swinging arm 26 whose length direction is in the vehicle width direction is connected to the top of the link member 25 by a pin 27, and the other end of the arm 26 is connected to the bracket 22, which is a stationary member, by a pin 28 for vertical swinging. is connected to. The above input shaft 21,
A crank mechanism-type rear wheel steering means 29 comprising a crank member 23, a link member 25, and a swing arm 26.
is constructed, and the crank member 2 is integrated with the input shaft 21.
3 rotates, the link member 25 also moves accordingly, but since the arm 26 that swings about the pin 28 is connected to the link member 25, the link member 25 moves freely. The link member 25 is restrained by the arm 26, which functions as a restraining member, so that the movement of the link member 25 becomes a swinging motion that is a combination of movement in the vertical direction and the horizontal direction, which is the width direction of the vehicle body. The restraint member is not limited to the swing arm 26 as long as it is capable of causing the link member 25 to perform a swing motion with at least a left-right movement component.

As shown in FIG. 1, the left and right rear wheels 30, 30 are supported by knuckle arms 31, 31 that are rotatable left and right,
The knuckle arm 31 is suspended by a shock absorber 32 whose upper end is connected to the vehicle body, and a lower arm 33 whose inner end is connected to the vehicle body so as to be vertically swingable.
The lower arm 33 of a vehicle equipped with the device according to the present invention depends on the suspension characteristics desired for the rear wheel suspension mechanism consisting of the shock absorber 32, the lower arm 33, etc.
is getting longer. Left and right rear wheel steering tie rods 3 are attached to the left and right knuckle arms 31, 31.
The outer ends of the tie rods 4 and 34 are connected, and the tie rods 34,
34 moves in the vehicle width direction, the rear wheel 3
0 is steered by the left and right rotation of the knuckle arm 31.

The inner ends of the left and right rear wheel steering tie rods 34, 34 are connected to the lower part of the link member 25 at the same height position by pins 35, 35, as shown in FIG. It is also possible to commonly connect the inner ends of both tie rods 34, 34 to the link member 25 by the same pin. As is clear from FIG. 2, in the first embodiment of the present invention described above, the link member 25 is connected to the pins 27, 35 that connect the swing arm 26 and the left and right rear wheel steering tie rods 34, 34 to the link member 25. The crank member 23 is connected to the crank member 23 by a pin 24 at an intermediate portion between the upper and lower connecting portions.

When the lower arm 33 is set to be long as described above, the left and right rear wheel steering tie rods 34, 34 also become long, but the vehicle body width of the link member 25 as an output member of the rear wheel steering means 29 to which the tie rods 34 are connected Since the dimension in the direction may be small, and therefore the rear wheel steering means 29 can be made compact, the inner ends of the tie rods 34, 34, which are opposite ends, are brought closer to each other and connected to the link member 25. Therefore, even if the length of the tie rod 34 whose length direction is in the vehicle body width direction increases, the vehicle width dimension of the vehicle does not increase.

When the steering wheel 10 is steered to the left, the front wheel 15 is steered to the left, and the crank member 23 and link member 25 rotate and swing as shown by the chain line in FIG.
The rear wheels 30 are steered via tie rods 34.
When the steered wheels 10 are steered to the right, the steering direction of the front wheels 15 and the rotating and swinging directions of the crank member 23 and the link member 25 are simply reversed, but the basic operation is the same. If a power steering device is attached to the gearbox 12, rear wheel steering will be performed with power assistance provided from the power steering device at the same time as front wheel steering, and the front wheel power steering device is separate from the front wheel power steering device. It is also possible to equip the vehicle with a rear wheel power steering device. In FIG. 2, crank member 2
3 is rotated by an angle α°, the link member 23 and the tie rod 34 are given a movement stroke in the horizontal direction x according to the magnitude of the rotation angle, and the graph in FIG. , the vertical axis is x.

Since x is the sine 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 no more than The positive and negative values are opposite values, and the value is maximum when α° is 270°. Therefore, when α° is an angle between 0° and 180°, the rear wheels 30 are steered in the same direction as the front wheels 15, but α is an angle between 180° and 360°. In this case, the rear wheels 30 can be steered in the opposite direction to the front wheels 15. The above explanation ignores the height component of the length of the tie rod 34 that changes with the rotation of the crank member 23, but the length of the tie rod 34 is long as described above, and this length is the same as that of the crank member 23. Since it is much larger than the vertical movement stroke of the pin 35 that moves with the rotation of the member 23, there is no problem in considering the length component of the tie rod 34 in the x direction as the actual length of the tie rod 34, so the above explanation is given. There is no essential 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 link member 25, and the speed change rate of the transmission mechanism is set appropriately to link the rotation angle of the steered wheel 10. Member 23
By arbitrarily determining the swing angle of the steering wheel 10
At a small steering angle, the front wheels 15 and rear wheels 30 are steered in the same direction, and at a large steering angle, the rear wheels 30 are steered in the opposite direction to the front wheels 15. It is possible to steer the front wheels 15 and the rear wheels 30 in the same direction and to make the steering angle of the rear wheels 30 zero or close to zero at a large steering angle.

The magnitude of the steering angle of the rear wheels 30 is determined by the crank member 2.
3. It is related to the respective length dimensions of the link member 25 and the swing arm 26 and the connection position of these members, and these rear wheel turning angle determining elements are dependent on the vehicle to which the device according to the present invention is applied. It is determined according to the ratio of the rear wheel steering angle to the front wheel steering angle, which is considered desirable.

4 to 6 and 7 to 9 show a second embodiment and a third embodiment of the present invention. In these embodiments, an input shaft that rotates in conjunction with the steering wheel is used. 51, 81, and a crank member 5 connected to the input shafts 51, 81 and having a length in the shaft outer diameter direction.
3, 83, link members 55, 85 connected to the crank members 53, 83, and crank members 5
The rear wheel steering means 59, 8 is controlled by the swinging arms 56, 86 as a restraining member that restrains the movement of the link members 55, 85 due to the rotation of the wheels 3, 83 into a swinging motion.
It is the same as the first embodiment in that the left and right rear wheel steering tie rods 64, 94 are connected to the link members 55, 85, but the crank members 53, 83 and the link members 55, 85 are connection position and link members 55, 85 and swing arm 5
6, 86, and the connection positions with tie rods 64, 94 are different from the first embodiment.

In the second embodiment shown in FIGS. 4 to 6, the link member 55 is connected to the swing arm 56 and the tie rod 64 by the pins 57 and 65 that connect the link member 55 to the link member 55. The tie rod 64 is connected to the crank member 53.
is connected to the link member 55 between the upper and lower swing arms 56 and the crank member 53. In the third embodiment shown in FIGS. 7 to 9, the link member 85
is connected to the crank member 83 by a pin 84 above the upper and lower connection portions formed by pins 87 and 95 that connect the swing arm 86 and tie rod 94 to the link member 85, and the swing arm 86
is connected to a link member 85 between the upper and lower crank members 83 and the tie rod 94.

Also in the steering apparatus according to each of the above embodiments, the horizontal movement stroke characteristics of the link members 55, 85 and tie rods 64, 94 shown in the graph of FIG. 10 can be obtained by the rotation of the crank members 53, 83. It is something.

As is clear from the above description, according to the present invention, the rear wheel steering means is constituted by an input shaft, a crank member, a link member, and a swing arm, and the loosely connecting member of the link member is loosely connected to the crank member. A swing arm that restricts the large rotation of the link member around the center to a rocking motion is provided between the link member and the immovable member that supports the input shaft, making the swing arm more compact in the vehicle width direction. Therefore, the rear wheel steering means can be made into a compact structure with a small size in the vehicle width direction. Even if the rudder tie rod is long, the present device can be assembled to the vehicle body without increasing the width of the vehicle.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the general basic structure of a vehicle equipped with a device according to a first embodiment of the present invention, FIG. 2 is a view in the direction of arrow 2 in FIG. 1, and FIG. -3
4 is a rear perspective view of a vehicle equipped with the device according to the second embodiment, FIG. 5 is a view taken in the direction of arrow 5 in FIG. 4, and FIG. 6 is a view taken along line 6-6 in FIG. Cross section, 7th
The figure is a rear perspective view of a vehicle equipped with the device according to the third embodiment, FIG. 8 is a view taken in the direction of arrow 8 in FIG. 7, FIG. 9 is a sectional view taken along the line 9-9 in FIG. 8, and FIG. is a graph showing the horizontal movement stroke of the link member and 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,
51, 81 are input shafts, 23, 53, 83 are crank members, 25, 55, 85 are link members, 26,
Reference numerals 56 and 86 are swing arms that are restraining members, 30 is a rear wheel, and 34, 64, and 94 are tie rods for steering the rear wheels.

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 wheel and is supported by a stationary member is provided. A swinging arm that connects a crank member having a length in the direction of the outer diameter of the shaft, loosely connects a link member to the crank member, and restrains the movement of the link member due to rotation of the crank member to a swinging movement. A steering device for a vehicle, wherein one end is swingably connected to the link member and the other end is swingably connected to the stationary member, and left and right rear wheel steering tie rods are connected to the link member. 2. Claim 1, wherein the link member is connected to the crank member at an intermediate portion of an upper and lower connecting portion that connects the swing arm and the right and left rear wheel steering tie rods to the link member. vehicle steering system. 3. According to claim 1, the link member is connected to the crank member at a position lower than the upper and lower connecting portions that connect the swing arm and the right and left rear wheel steering tie rods to the link member. vehicle steering system. 4. Claim 1, wherein the link member is connected to the crank member at a position above the upper and lower connecting portions that connect the swing arm and the right and left rear wheel steering tie rods to the link member. vehicle steering system.