JP2666324B2 - Steering angle ratio control mechanism - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering angle ratio control mechanism of a four-wheel steering vehicle in which a steering angle ratio of a rear wheel mechanically changes according to a front wheel steering angle.

2. Description of the Related Art A steering angle ratio control mechanism disclosed in Japanese Patent Application Laid-Open No. 55-91458 has an S-shaped cam groove provided on a sliding plate that moves back and forth in association with front wheel steering, and this cam groove has a rear end. The pin of the wheel steering tie rod is engaged. According to the steering angle ratio control mechanism described above, while the front wheel steering angle is small, the rear wheels are steered in the same phase as the front wheels, and stable movement of the vehicle body can be obtained when changing lanes during high-speed running. On the other hand, when the front wheel steering angle is increased, the rear wheels are steered in the opposite phase to the front wheels, and the small turning performance at low speed traveling is improved.

However, in the steering angle ratio control mechanism described above, the operation of the steering wheel is transmitted to the rear wheel by sliding the cam groove of the sliding plate and the pin of the rear wheel steering member. If play occurs due to wear of the sliding portion, steering angle accuracy of the rear wheel and stability of the rear wheel are impaired.

The steering angle ratio control mechanism disclosed in Japanese Utility Model Laid-Open Publication No. Sho 62-165176 is described with reference to the reference numeral in the publication.The gear 25f of the support 25 that meshes with the worm 24c that rotates in conjunction with the steering wheel includes a vertical shaft 25d, When the support 26 rotates around the center 25e, the support 26, which is rotatably supported inside the support 25 by bearings 35 and 36 coaxially with the output rod (tie rod) 14, also rotates about the vertical shafts 25d and 25e. Then, the projection 27 protruding from the output rod 14 and having the tip held by the support 26 via the ball joint 29 moves left and right, the output rod 14 moves right and left together with the projection 27, and the rear wheel is moved to the front wheel. And steer in phase. The projection 27 is directed forward in FIG. 2, but if the projection 27 is turned up and down via the motor 43, the worm gear mechanism T1, and the output rod 14, no steering is performed. Become steering.

The steering angle ratio control mechanism described above changes the direction of the protrusion 27 coupled to the tie rod 14 via the motor 43, the worm gear mechanism T1, and the tie rod 14 according to the vehicle speed and the like.
Since the steering angle ratio and the forward / backward phase are adjusted, the configuration is very complicated, and when the motor fails, the steering angle ratio cannot be controlled.

[Problems to be Solved by the Invention] An object of the present invention is to convert a front-rear movement or a rotational movement related to front wheel steering into a front-rear movement of a rear wheel steering member, and to keep the front wheel in phase with a small front wheel steering angle. Another object of the present invention is to provide a steering angle ratio control mechanism which has a simple structure, is stable in operation, and has excellent durability, in which the rear wheels are steered in the opposite phase to the front wheels when the front wheel steering angle increases.

[Means for Solving the Problems] In order to achieve the above object, the configuration of the present invention is configured such that a gear box is rotatably supported on a vertical shaft fixed to a vehicle body, and the gear box is associated with front wheel steering. An input means for rotating, and a bevel gear coupled to the upper and lower shafts inside the gear box is meshed with a front and rear shaft bevel gear rotatably supported by the gear box,
An output arm projecting from the rear end of the front-rear shaft to the other side is connected to one end of a relay lever supported on the vehicle body via a first front-rear link, and the other end of the relay lever is connected via a front-rear link. The rear wheel is connected to a rear wheel nut, and the rear wheel is steered by the longitudinal displacement of the link in the first longitudinal direction.

[Action] For example, when the steering wheel is turned to the right, the input rod moves forward, the gear box rotates about the vertical axis together with the input arm, and the bevel gear fixed to the vertical axis inside the gear box. The output arm connected to the longitudinal axis of the meshing bevel gear rotates. When the output arm rotates around the vertical axis, the link as a steering member moves backward or forward to rotate the relay lever, and the relay lever rotates the rear wheel knuckle. When the front wheel steering angle increases, the rear wheels are steered in the same phase as the front wheels and in the opposite phase to the front wheels.

FIG. 1 is a plan view showing a schematic configuration of a four-wheel steering vehicle provided with a steering angle ratio control mechanism. A knuckle arm 3 supporting the front wheel 2 is rotatably supported on the vehicle body by a vertical support shaft 3a, and a pair of left and right knuckle arms 3 are interlocked and connected by tie rods 4. For example, when the steering wheel 5 is turned right, the rotation of the steering shaft 6 is converted into the rotation of the output shaft 9 of the front wheel steering mechanism 8. The drop arm 7 connected to the output shaft 9 moves the drag link 11 connected to the drop arm 7 forward. The rear end of the drag link 11 is connected to the right knuckle arm 3, rotates the knuckle arm 3 clockwise about the support shaft 3a, and steers the front wheel 2 to the right.

At the same time, the input rod 12 connected to the middle part of the drop arm 7 by the pin 10 moves forward, and the input rod 12
Arm of the steering angle ratio control mechanism A connected to the ball joint 13
14 is rotated counterclockwise about the vertical shaft 36 together with the gear box 29.

The input rod 12 and the input arm 14 of the gear box 29 connected to the input rod 12 constitute input means for rotating the gear box 29 in relation to front wheel steering. A longitudinal axis that couples the circumferential arm 15 with a counterclockwise rotation about the vertical axis 36 of the gear box 29
32 rotates together with the gear box 29, and at the same time, the output shaft 15
Rotate around 32. The rotation of the output arm 15 causes the first longitudinal link 17 connected by the ball joint 16 to move backward or forward.

At one end of the relay lever 19 supported on the vehicle body by the support shaft 20,
While the first link 17 is connected by the ball joint 18, the other end of the relay lever 19 is connected to the second link in the front-rear direction by the pin 21.
22 front ends are connected. The rear end of the second link 22 is connected by a pin 23 to an arm projecting sideways from the knuckle arm 25. A nut arm 25 supporting the rear wheel 24 is rotatably supported by the vehicle body by a vertical support shaft 25a. The left and right knuckle arms 25 are linked and connected by tie rods 26.
Therefore, the forward / backward movement of the first link 17 as a rear wheel steering member is converted into rotation about the support shaft 20 of the relay lever 19, and further, the nut arm 25 is moved through the second link 22.
Is rotated around the support shaft 25a, and the rear wheel 24 is steered to the right or left.

FIG. 2 is a plan sectional view of the steering angle ratio control mechanism, and FIG. 3 is a side sectional view of the same. Inverted L-shaped bracket on the wall 27 of the body
28 is fixed, and the vertical shaft 36 is supported so as not to rotate,
And fastened by a nut 39. The bevel gear 30 is formed integrally with the upper end of the vertical shaft 36. Bearings 37, 38 for vertical shaft 36
Supports the gear box 29. The input arm 14 connected to the gear box 29 is connected to the rear end of the input rod 12 by the ball joint 13.

A front and rear shaft 32 is supported by a bearing 33 on the rear wall of the gear box 29. A bevel gear 31 is formed integrally with the inner end of the front-rear shaft 32, and meshes with the bevel gear 30 inside the gear box 29. The outer end of the front-rear shaft 32 is fitted into a serration hole of the output arm 15 and fastened by a nut 35. The tip of the output arm 15 is connected by a ball joint 16 to the front end of a first link 17 as a rear wheel steering member.

Next, the operation of the steering angle ratio control mechanism according to the present invention will be described. When the handle 5 is in the neutral position (the straight traveling position of the vehicle), the input arm 14 projects rightward as shown in FIG.
The output arm 15 projects horizontally to the left. When the handle 5 is turned to the right as described above, the input rod 12 is pulled forward in FIG. 2 and the gear box 29 rotates counterclockwise. At this time, the front and rear shafts together with the bevel gear 31 meshing with the immovable bevel gear 30
32 is rotated clockwise as viewed from the rear of the vehicle body. Output arm 15
As a whole, the tip of the output arm 15 turns upward from the horizontal plane while turning counterclockwise in the horizontal plane. Accordingly, when the first link 17 first moves rearward, the knuckle arm 25 rotates clockwise about the support shaft 25a via the relay lever 19, and the rear wheel 24 is steered to the right.

However, when the steering angle of the handle 5 increases, the gear box 29 also rotates around the vertical shaft 36 in proportion to the steering angle. However, when the rotation angle of the output arm 15 around the longitudinal axis 32 exceeds 90 °,
Fall to the right from an upright position. As a result, the front-rear distance between the output arm 15 and the relay lever 19 is reduced, and the relay lever 19 that has been rotated counterclockwise around the support shaft 20 is now rotated clockwise, and the rear wheel 24 is rotated. The steering is performed in the opposite phase to the front wheels 2.

When the handle 5 is turned to the left, the input rod 12 moves backward, the gear box 29 rotates clockwise about the vertical shaft 36, and the output arm 15 rotates counterclockwise as viewed from the rear of the vehicle body. . While the turning angle of the steering wheel is small, the first link 17 moves forward, and the rear wheel 24 is steered in the same phase as the front wheel 2,
As the steering angle of the handle 5 increases, the tip of the output arm 15 moves downward, the first link 17 moves backward, and the rear wheel 24 is steered in the opposite phase to the front wheel 2.

The rear wheel steering angle with respect to the steering angle of the steering wheel 5 exhibits characteristics as shown in FIG. The turning angle θ of the steering wheel 5 at which the rear wheel steering angle returns to 0 is determined by the gear ratio of the bevel gears 30 and 31, and takes a value smaller than the rotation angle 90 ° at which the output arm 15 is in the upright or hanging position.

In the embodiment shown in FIGS. 5 and 6, a partial bevel gear 43 is provided on the front wall of the gear box 29 as input means for rotating the gear box 29 in relation to the front wheel steering. The bevel gear 42 connected to the input shaft 41 that rotates in association with the above operation is meshed. Other configurations are the same as those of the embodiment shown in FIGS. 2 and 3 and operate similarly.

[Effects of the Invention] As described above, the present invention includes an input unit that rotatably supports a gear box on an upper and lower shaft fixed to a vehicle body and rotates the gear box in relation to front wheel steering. A bevel gear of the front and rear shaft rotatably supported by the gear box is meshed with a bevel gear connected to the vertical shaft inside the box, and an output arm projecting from the rear end of the front and rear shaft to the other side is connected to the first arm. The link is connected to one end of a relay lever supported by the vehicle body via a link in the front-rear direction, and the other end of the relay lever is connected to the rear wheel nut via the link in the front-rear direction. Since the wheels are steered, the characteristics of the rear wheel steering angle ratio can be determined by appropriately setting the gear ratio of the front and rear shaft bevel gears to the upper and lower shaft bevel gears. Durable because it is small as a whole and has no sliding parts The steering angle ratio is controlled with high accuracy, reliable operation, and high accuracy.

[Brief description of the drawings]

FIG. 1 is a plan view showing a schematic configuration of a four-wheel steering vehicle provided with a steering angle ratio control mechanism according to the present invention, and FIG. 2 is a plan sectional view of a steering angle ratio control mechanism according to a first embodiment of the present invention. FIG. 3 is a side sectional view of the same, FIG. 4 is a characteristic diagram of the steering angle ratio control mechanism, and FIG.
FIG. 6 is a plan sectional view of a steering angle ratio control mechanism according to a second embodiment of the present invention, and FIG. 6 is a side sectional view of the same. 12: Input rod, 13, 16: Ball joint, 14: Input arm, 15: Output arm, 17: Link, 28: Bracket, 29: Gear box, 30, 31: Bevel gear, 32: Front and rear shaft, 36: Vertical Shaft, 41: input shaft, 42: bevel gear,
43: Partial bevel gear

Claims (1)

(57) [Claims] 1. A gear box is rotatably supported on a vertical shaft fixed to a vehicle body, and input means for rotating the gear box in relation to front wheel steering is provided. The coupled bevel gear is meshed with a front and rear shaft bevel gear rotatably supported by the gear box, and an output arm projecting from the rear end of the front and rear shaft to the other side is connected to the vehicle body via a first longitudinal link. And the other end of the relay lever is connected to the rear wheel nut via a front-rear link.
A steering angle ratio control mechanism for steering a rear wheel by a longitudinal displacement of a link in a longitudinal direction of the vehicle.