JPH04232182A - Wheel steering device - Google Patents

Abstract

PURPOSE:To perform a small-radius turning and parallel movement freely by turnably supporting a steering shaft to a supporting member through an worm gear mechanism to rotate each wheel independently more than 90 deg. within the range in which each wheel does not touch the supporting member. CONSTITUTION:A supporting member 6 for wheel driving motor 5 is provided on a shock-absorber 3 for axle type suspension 2. Also an worm gear 7 and a steering motor for driving the worm gear are mounted on the supporting member 6. In addition, a steering shaft 10 is supported a hole 8 provided in the supporting member 6, rotatably through upper and lower bearings 11, 12. On the other hand, an worm wheel 13 meshed with the worm gear 7 is provided between the upper and lower bearings 11 and 12. Then the steering shaft 10 is supported turnably on the supporting member 6 by worm gear mechanisms 7, 13. Thus the wheels 15 can be rotated more than 90 deg. without touching the supporting member 6.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering system for a vehicle whose wheels can be steered.

0002

2. Description of the Related Art In recent years, automobiles have appeared that incorporate a so-called four-wheel steering (4WS) mechanism that steers both the front wheels and the rear wheels when the vehicle turns. In this way, according to the four-wheel steering mechanism, when the vehicle turns to change lanes while driving at high speed, the front wheels and rear wheels are steered in the same phase, thereby steering the vehicle body significantly inward in the direction of travel. It is possible to generate centripetal force without directing it. Therefore, the shaking of the vehicle body is reduced, and driving stability can be improved. In addition, when driving at low speeds, the front and rear wheels may be steered in opposite phases to make a short turn for parking, for example, or to move in parallel for parallel parking, etc. By steering the two in the same phase, maneuverability can be improved.

By the way, in order for a four-wheeled vehicle to turn smoothly, it is necessary for all four wheels to have the same turning center. For this purpose, conventional steering mechanisms employ, for example, a steering link mechanism that includes a knuckle arm and a tie rod.

As shown in FIG. 6, this steering link mechanism connects a tie rod 01 and a knuckle arm 02 so as to be relatively rotatable by a tie rod end 01a, and connects the other end of the knuckle arm 02 to the king pin 0 of the left and right wheels.
It has a structure that connects to 3. Then, the tie rod 01 of the steering link mechanism is moved from side to side by transmitting the turning torque from the steering handle through, for example, a rack and pinion, a worm gear, or a hydraulic cylinder. Then, the left and right movement of the tie rod 01 causes the knuckle arm 02 to rotate, and the left and right wheels are steered left and right.

However, in such a steering link mechanism, once the tie rod 01 and the knuckle arm 02 are aligned in a straight line as shown in FIG. 6, the wheels cannot be steered any further. That is, this state is the limit of possible wheel steering, and the limit angle of the steering angle α is usually around 45°. If there is a limit to wheel steering as described above, steering for making a tight turn will be restricted.

[0006] Furthermore, even if the steering angle α of the wheels were to exceed such a limit angle, for example, to make it possible to turn up to 90°, if the steering angle was set to 90°, the drive from the drive source provided in the vehicle body would be reduced. A problem arises in that the wheels cannot be driven depending on the force.

Therefore, as shown in FIG. 7, in order to mechanically transmit the steering angle of the steering wheel to the wheels 101 via the link mechanism 100, etc., the present applicant increases the speed with the speed increasing gear 103, thereby increasing the steering angle of 90° or more. Invented a mechanism that enables steering and independently provides a driving motor 102 for each wheel 101 so that the wheel 101 can be rotated by the driving motor when the wheel 101 is steered by 90 degrees. Patent application filed (Japanese Patent Application No. 165498/1983)
. Note that in FIG. 7, a wheel steering motor 107 is disposed below the brake mechanism 106.

Therefore, if a steering mechanism using such a speed increasing gear 103 is used for the front and rear wheels, both the front wheels and the rear wheels can be steered by 90 degrees. It becomes possible to move it.

Furthermore, a four-wheel steering mechanism as shown in FIG. 8 (Japanese Unexamined Patent Publication No. 59-190056) or FIG. 9 (Japanese Unexamined Patent Application No. 59-199358) is known. In the example of FIG. 8, the driving force of the steering worm gear 111 is the worm wheel 110.
, is transmitted to the steering shaft 114 which is spline-engaged with the gear 113 via the gears 112 and 113, and determines the steering direction of the wheels 115. Further, the example shown in FIG. 9 has a worm gear 122 driven by a steering motor 121.
The wheels 125 are steered by means of a worm wheel 123, a pulley 124, and the like.

0010

[Problems to be Solved by the Invention] In all of the above-mentioned conventional technologies, the steering mechanism of the wheels largely overhangs the upper part of the wheels, and the vehicle body frame is provided above that. I can't put it down. Further, in the invention according to the patent application filed by the present applicant, as shown in FIG. 7, by increasing the speed increasing ratio of the speed increasing gear 103, the steering angle can be increased accordingly. For example, if the speed increase ratio is doubled, the wheels 101 can be steered at a steering angle of 90° even if the actual steering angle of the steering angle steering mechanism is 45°. However, since the diameter of the speed-increasing internal gear is limited, a configuration of the speed-increasing gear 103 that can actually obtain a double speed-increasing ratio cannot be adopted. Furthermore, if the speed increasing gear 103 and knuckle arm 104 are installed in a low position, the two supporting wheels 101
A problem arises in that the distances between the bearings 105 become shorter, and the rigidity of the wheel 101 in the longitudinal and lateral directions becomes lower. Furthermore, in the steering mechanism using the link mechanism 100, a brake mechanism 106 must be provided to prevent the steering motor 107 from rotating due to input from the wheels 101.

Furthermore, in the steering mechanism using the link mechanism 100, the steering angles of the left and right wheels have a certain relationship, so there is a drawback that it is not possible to achieve both tight turning and parallel movement. In other words, for example, when driving a vehicle in a small turn,
While it is necessary to steer the rear wheels in an opposite phase to the front wheels, when moving the vehicle in parallel in a desired direction, it is necessary to steer the rear wheels in the same phase as the front wheels. Moreover, it is not only necessary to change the absolute value of the steering angle ratio of the front and rear wheels depending on whether the vehicle is running in a short radius or moving in parallel.
Even in the same small turn or parallel movement, it is necessary to change the absolute value of this steering angle ratio depending on the magnitude of the steering angle of the front wheels.

Furthermore, in the example shown in FIG.
08 had to be provided through the vehicle body frame 109, a hole had to be made in the vehicle body frame 109.

Furthermore, in the steering device using the worm gear mechanism shown in FIGS. 8 and 9, wheels 115 and 125 are provided, respectively.
Since the worm gears 111 and 122 are located at the top, the worm wheel house cannot be placed in a low position.

[0014] Therefore, the object of the present invention is to be able to obtain a steering angle of any desired size without using a speed increasing mechanism, to be able to achieve both small turning and parallel movement, and to be able to place the vehicle frame at a low position. An object of the present invention is to provide a wheel steering device.

[0015]

[Means for Solving the Problems] In order to achieve the above object, the present invention employs the following configuration.

That is, a wheel support member is elastically supported by the vehicle body and includes a worm gear and a worm gear drive motor; a wheel support member is rotatably supported by bearings at two upper and lower locations on the support member; a wheel steering shaft having meshing worm wheels between the bearings;
The wheel steering device is characterized in that wheels supported at an end portion of the wheel steering shaft opposite to an end portion on the rotation support side by the support member are provided around each wheel.

[0017]

[Operations and Effects of the Invention] The worm gear mechanism allows the steering shaft to rotate freely relative to the support member, and the wheels can rotate over 90° without contacting the support member. Since each wheel can rotate independently of each other, small turns and parallel movements can be made freely.

Furthermore, the connection between the support member and the steering shaft can be made compact since it is sufficient to have space for two bearings and a worm gear, upper and lower. Furthermore, since the support member and the steering shaft are connected by a worm gear mechanism between the upper and lower bearings, there is no need to shorten the length between the two bearings.
Increased rigidity for wheel support. In addition, by adopting a worm gear mechanism, a large reduction ratio can be achieved.
Since the worm gear drive motor does not need to be provided with a brake due to automatic tightening of the worm gear, the motor can be made compact. Further, since the diameter of the worm wheel of the steering shaft can be made larger than the external gear of the speed increasing gear, it is possible to reduce rattling between the gears due to backlash.

Furthermore, since the wheels are supported at the end of the wheel steering shaft opposite to the end on the rotation support side by the support member, the steering shaft and the wheels can be arranged in parallel, and the wheel steering shaft It can be placed below the outer diameter portion of the wheel, and interference from the vehicle body frame can be prevented.

[0020]Also, reducing the length (inter-axle distance) between the grounding point of the wheel and the contact point on the extension line of the axis of the steering shaft is a requirement for light steering, but it is not possible to use a speed increasing gear. Therefore, the distance between the axes can be reduced accordingly.

[0021]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view of the steering device of this embodiment in a state where it is attached to a vehicle body, FIG. 2 is a partial sectional view (A) of FIG. 1, and FIG. 2 is a partial sectional view (B) of FIG. 1. It is. 4 is a cross-sectional view taken along the line II--II in FIG. 2, and FIG. 5 is a cross-sectional view taken along the line II--II in FIG.

As shown in FIGS. 2 and 3, the upper end of a shock absorber 3 of an axle suspension 2 is supported by a vehicle body frame 1. As shown in FIGS. The shock absorber 3 is also provided with a support member 6 that supports a wheel drive motor 5, and this support member 6 is provided with a worm gear 7 and a steering motor 9 that drives the worm gear 7 (FIGS. 4 and 5). ) is provided. Further, a hole 8 is bored in the support member 6 in parallel with the shock absorber 3. A steering shaft 10 is rotatably supported in the hole 8 by two upper and lower bearings 11 and 12 around the central axis of the hole 8 . A support member 6 is provided between the upper and lower bearings 11 and 12 of the steering shaft 10.
A worm wheel 13 that meshes with the worm gear 7 is provided. In this way, the steering shaft 10 and the wheels 15 integrated therewith are rotated within the range of wheel positions (a) to (c) shown in FIG.

As shown in FIG. 5, a motor case 20 of the wheel drive motor 5 is attached to the lower end of the steering shaft 10. As shown in FIG. In that case, the mounting surface 20a of the cylindrical member 10a of the steering shaft 10 in this motor case 20 is
It is formed on an inclined surface perpendicular to the central axis 10b. A stator 21 fixed to the motor case 20, a rotor 23 fixed to the motor rotating shaft 22, a planetary reduction gear 24, and the like are disposed inside the motor case 20. The stator 21, the motor rotation shaft 22, and the rotor 23 constitute the wheel drive motor 5.

[0024] Also, one end of the motor rotation shaft 22 is connected to the output shaft 2.
The motor rotating shaft 22 and the output shaft 25 are disposed on the same axis. A planetary reduction gear 24 is disposed at the fitting portion of both shafts 22 and 25, so that the power is reduced and transmitted from the motor rotating shaft 22 to the output shaft 25 via the planetary reduction gear 24. It has become. Further, a wheel 26 and a wheel 15 are attached to the other end of the output shaft 25. In this way, the wheel drive motor 5 and the wheels 15 are integrally combined. This wheel drive motor 5 allows the wheels 15 to be rotationally driven without being affected by the steering angle of the wheels 15. In that case, the center axis 10b of the steering shaft 10 serves as the rotation center axis for steering the wheels 15.

Wheel drive motor 5 arranged in this way
, bearings 11, 12, worm gear mechanisms 7, 13, etc., although not shown, are arranged symmetrically and in the same configuration with respect to the left and right wheels.

[0026] Thus, the worm gear mechanism 7, 13 allows the steering shaft 10 to rotate freely relative to the support member 6, and the wheels 15 can rotate over 90° or more within a range that does not come into contact with the support member. Since each wheel 15 can rotate independently of each other, small turns and parallel movements can be made freely.

Furthermore, the connection between the support member 6 and the steering shaft 10 can be made compact since it is only necessary to have a space for the two bearings 11 and 12, upper and lower, and the worm gear 7; Since the bearings 11 and 12 are connected by worm gear mechanisms 7 and 13 between the bearings 11 and 12,
There is no need to shorten the length between both bearings 11 and 12,
The rigidity of supporting the wheels 15 increases.

Furthermore, by adopting the worm gear mechanisms 7 and 13, a large reduction ratio can be achieved, and since the worm gear is automatically tightened, there is no need to provide a brake on the steering motor 9 that drives the worm gear, so the motor 9 can be made compact. can. Furthermore, since the diameter of the worm wheel of the steering shaft 10 can be increased, rattling between gears due to backlash can be reduced.

Furthermore, since the wheels 15 are supported by the motor case 20 at the opposite end of the wheel steering shaft 10 from the end on the rotation support side by the support member 6, the steering shaft 10 and the wheels 15 are Can be arranged in parallel, the wheel steering shaft 10 is connected to the wheel 15
It is possible to dispose it below the outer diameter part of the body frame 1, and interference from the vehicle body frame 1 can be prevented.

Furthermore, reducing the length (inter-axle distance) between the grounding point of the wheels 15 and the grounding point on the extension of the axis of the steering shaft 10 is a requirement for light steering of the steering wheel.
Since a speed increasing gear or the like is not used, the distance between the shafts can be reduced accordingly.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of the present invention in which a steering device according to the embodiment is attached to a vehicle body.

FIG. 2 is a partial cross-sectional view of FIG. 1 (A).

FIG. 3 is a partial cross-sectional view of FIG. 1 (B).

FIG. 4 is a sectional view taken along line II in FIG. 2;

FIG. 5 is a sectional view taken along the line II-II in FIG. 4;

FIG. 6 is an explanatory diagram of wheel steering.

FIG. 7 is a configuration diagram of a conventional wheel steering device.

FIG. 8 is a configuration diagram of a conventional wheel steering device.

FIG. 9 is a configuration diagram of a conventional wheel steering device.

[Explanation of symbols]

1 Body frame 3 Shock absorber 5 Wheel drive motor 6 Support member (wheel support member) 7 Worm gear 9 Steering motor 10 Steering axis (wheel steering axis) 11 Bearing 12 Bearing 13 Worm wheel 20 Motor case

Claims (1)

[Claims] 1. A wheel support member elastically supported by a vehicle body and comprising a worm gear and a worm gear drive motor;
A wheel steering shaft rotatably supported by bearings at two upper and lower locations on the support member and having a worm wheel between the bearings that meshes with a worm gear of the support member; A wheel steering device comprising: a wheel supported at an end opposite to a dynamic support side end.