JPH04121281A - Rear-wheel steering device for vehicle - Google Patents

Abstract

PURPOSE:To obtain a compact and efficient rear wheel steering device with a large degree of freedom for control by inclining a guide member with a sub- motor, rotating rod members with a main motor, and moving them in the axial direction to steer rear wheels. CONSTITUTION:When a sub-motor 127 is rotated, a sector gear 119 is rotated via a gear, and a rod pivot 110 is inclined. When the output shaft of a main motor 136 is rotated in response to the steering of front wheels, a driving shaft 131 is rotated via bevel gears 135, 134, and a driving member 130 is moved in the axial direction, a sector shaft 111 is rotated, and a rod member 103 is rotated. A shaft 108 is rotated around the axis of the rod member 103, it is forcefully moved in the axial direction, the rod member 103 is moved in the axial direction to move steering rod members 106, 107, and rear wheels are steered. A compact rear wheel steering device can be obtained, the loss of the drive torque is suppressed, and an efficient reduction system can be obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a rear wheel steering device for a vehicle.

[Prior Art] In recent years, rear wheel steering devices for vehicles, particularly automobiles, have been developed, and some are already on the market. Japanese Patent Publication No. 61-163
Japanese Patent No. 064 describes an example of such a rear wheel steering device. This rear wheel steering device will be explained below with reference to FIG. 7.

Figure S7 is a sectional view of a rear wheel steering device according to the prior art.

An input shaft 701 whose front end is connected to a front wheel steering mechanism (not shown) has a ohm 702 coaxially attached thereto. Worm 702 meshes with ohm wheel 703. The ohm wheel 703 is connected to the double cylinder 704 with their axes orthogonal to each other,
When the ohm wheel 703 rotates, the double cylinder pivots clockwise or counterclockwise relative to the plane of the paper.

The double cylinder 704 consists of an outer cylinder 704a and an inner cylinder 704b, and the inner cylinder 704b is rotatable with respect to the outer cylinder 704a. Open lower 04c in part of inner cylinder 704b
A shaft 7 is provided so as to be able to pivot freely on this opening lower 04c.
05 is engaged. The shaft 705 is attached to the outer periphery of the rod 706 and moves together with the rod 706 in the axial direction of the rod. Both ends of the rod 706 are connected to a steering mechanism (not shown), and wheels (not shown) are steered by the axial direction of the rod 706.

Here, it is assumed that when the rod 706 moves to the left, the rear wheels are steered to the left, and when the rod moves to the right, the rear wheels are steered to the right.

The rod 706 is rotatably supported around an axis, and the rotational force of the motor 708 is transmitted to the rod 706 via a worm mechanism 707. When the row door 06 rotates, the shaft 705' rotates around the axis of the IJ rod 706 accordingly.

The operation of this conventional rear wheel steering device will be described below.

At the position of the shaft 705 (facing upward) shown in FIG. 7, the input shaft 701 connected to the front wheel steering mechanism is rotated by the steering operation of the 1M driver, and the ohm wheel 703 is rotated counterclockwise. When rotated to
Accordingly, the shaft 705 is moved to the seventh position along with the rod 706.
Moving to the left in the figure, the rear wheels are steered to the left, that is, in phase with the front wheels, and by an amount corresponding to the amount of steering of the front wheels.

On the other hand, if the rod 706 is rotated by the rotation of the motor 708 and the shaft 705 is moved to a position opposite (facing downward) from the position shown in FIG. When the ohm wheel 703 similarly rotates counterclockwise, the shaft 705 moves to the right in FIG. The steering is turned by an amount corresponding to the amount of rudder.

Furthermore, as is clear from the above description, when the shaft 705 is perpendicular to the plane of the paper, the rod 706 does not respond to the rotation of the ohm wheel 703, and the steering of the rear wheels is controlled by the driver. This will not be done at all regardless of the steering operation.

That is, if the position of the shaft 705 is controlled by the motor 708, the amount of steering of the rear wheels can be changed steplessly from the maximum positive phase amount to zero and from zero to the maximum amount of reverse phase depending on the amount of steering of the front wheels. I can do it.

[Problem to be solved] By the way, in such a conventional rear wheel steering device,
A portion of the steering torque for steering the front wheels is mechanically transmitted to rotate the worm wheel 703. Therefore, a mechanical means for transmitting steering torque similar to a propeller shaft is needed. However, space is a major constraint in passenger cars, and using such a mechanical transmission means would result in a narrow passenger compartment, which requires a large volume, and would also increase weight, as well as reduce sliding movement. The loss of torque due to the increase in torque cannot be ignored.

SUMMARY OF THE INVENTION An object of the present invention is to provide a rear wheel steering device for a vehicle that is compact, efficient, and has a large degree of freedom in control.

[Means to solve problems] The rear wheel steering device for a vehicle according to the present invention is as follows.

a main motor; a sub-motor; a rod member that steers the rear wheels by moving in the axial direction; a guide member having a guide path that is tilted relative to the axis of the rod member by the rotational force of the sub-motor; It consists of an actuating member that protrudes radially from the rod member and is guided by the guide path, and the rod member rotates around the axis due to the rotational force of the main motor, thereby causing the actuating member to follow the guide path. When the actuating member rotates around the rod member, the actuating member adjusts the amount of rotation of the rod member and the amount of rotation of the guide member. The rear wheel is steered by moving along with the rod member in the axial direction of the rod member by a distance corresponding to the amount of tilting of the guideway.

[Function] According to the vehicle rear wheel steering device of the present invention, since the sub motor tilts the guide member and the main motor rotates the rod member, it is possible to obtain a compact rear wheel steering device. This reduces drive torque loss and increases control flexibility.

[Example 1] Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a main part of a rear wheel steering device of a vehicle according to the present invention. Inside the housing 101, a rod member 103 is supported by a sliding bearing 102 so as to be rotatable and movable in the axial direction.

Both ends of the rod member 103 are connected to a pole joint 104.
It is rotatably connected to steering rods 106 and 107 by 105. The steering rods 106 and 107 are connected to steering mechanisms for the left and right rear wheels, respectively, and the rear wheels are steered by moving the steering rods in the axial direction.

A cylindrical shaft 108, which is an operating member, is implanted in the center of the rod member 103 so as to protrude in the radial direction. A sliding support member 109 is attached to the outer periphery of the shaft 108. The outer peripheral surface of the sliding support member 109 is spherical.

A rod pivot 110, which is a guide member, is provided so as to enclose the shaft 108. The rod pivot 110 consists of an outer cylinder 110a, an inner cylinder 110b, and a roller 110c interposed therebetween.
is rotatably supported by the outer cylinder 110a. The sliding member 109 of the shaft 108 is inserted into an opening 110g provided in the inner cylinder 110b. As will be described later, the sliding member 109 has a spherical outer peripheral surface so as not to interfere with the inner wall of the opening 110g even when the rod pivot 110 is tilted.

The periphery of the rod pivot 110 will be explained with reference to FIGS. 4 and 5.

FIG. 4 is a sectional view taken along line IV--IV in FIG. 1. FIG. 5 is a cross-sectional view taken along line v--v in FIG. 4.

In FIG. 4, shaft 108 is shown rotated 90 degrees from the position shown in FIG. Pivot shafts 110d and 110e project horizontally from the outer periphery of the rod pivot 110, and the pivot shaft 110e is rotatably supported by a bearing 116 consisting of a ball 114 and a race member 115. The race member 115 comes into contact with a pressing member 117 having a threaded portion on its outer periphery, and by screwing the pressing member into the housing 101, the bearing 116 is
It is pressed in the direction of the rod pivot 110 to absorb the play of the bearing.

The pivot shaft 110d is fitted and attached to the rotation center of the fan-shaped gear 119, and rotates integrally with the fan-shaped gear 119. The sector gear 119 is rotatably supported by the housing 101 by a bearing 118.

A protrusion 110f is coaxially formed at the tip of the pivot shaft 110d, and the protrusion 110f is connected to the coupling 120.
It is connected to the input shaft 121a of the rotation angle sensor 121 via the rotation angle sensor 121. Therefore, the amount of rotation of the sector gear 119, that is, the amount of tilting of the rod pivot 110, can be measured by the rotation angle sensor 121, and can be used as data for foot hack control, for example. Note that FIG. 1 shows a state in which the rod pivot 110 is at its maximum angle position, and from this state, the rod pivot 110 can only be tilted counterclockwise on the plane of the paper.

The sector gear 119 meshes with a worm gear 123 formed on the outer periphery of the upper intermediate shaft 122.

As shown in FIG. 5, the intermediate shaft 122 is rotatably supported by the housing 101. A large gear 124 is coaxially attached to one end of the intermediate shaft 122, and the large gear 124 meshes with a small gear 125 that is also rotatably supported. Small gear 125 is connected to output shaft 127a of sub-motor 127 via coupling 126.

Returning to FIG. 1 again to continue the detailed description of the present invention, a male spline portion 1 is provided in a rightward portion of the rod member 103.
03a is formed over the entire circumference. A sector shaft 111 having a female spline portion 111a is provided outside the male spline portion 103a.
a is engaged with the female spline portion 111a. That is, the sector axis Ill cannot rotate relative to the rod member 103, or can move relative to the rod member 103 in the axial direction.

The sector shaft 111 is rotatably supported with respect to the housing 101 by bearings 112 and 113. A pressing cylinder 101b that can be screwed into the housing 101 or a bearing 113
The sector shaft 111 is pressed against the sector shaft 111 by means of which the play of the bearings 112, 113 is adjusted.

The periphery of the sector axis 111 will be explained with reference to FIGS. 2 and 3.

FIG. 3 is a sectional view taken along the line m--■ in FIG. 1. FIG. 2 is a sectional view taken along line U-II in FIG. 3.

In FIG. 3, a sector shaft 111 attached around the rod member 103 has a pinion 111b on its outer periphery, and the pinion 1llb meshes with a rack 130a formed on the outer periphery of the drive member 130. Drive member 13
0 is screwed onto the outer periphery of a drive shaft 131, which has a spiral groove (only a portion shown) 131a formed on the outer periphery. Drive shaft 13
1 is rotatably supported by the housing 101 by bearings 132 and 133. Drive member 130 and spiral groove 13
A large number of balls 130b are interposed between the ball 1a and the ball 1a.
The ball 130b can move within the spiral groove 131a. That is, the driving member 130, the driving lIl
31a and the ball 130b form a so-called ball-nut mechanism. Therefore, when the drive shaft 131 rotates, the drive member moves leftward or rightward depending on the direction of rotation.

The drive shaft 131 has a large bevel gear 134 attached to its end, and the large bevel gear 134 engages with a small bevel gear 135 .

As shown in FIG. 3, the small bevel gear 135 is connected to the main motor 1.
36 output shaft 136a.

Next, the operation of the embodiment of the vehicle rear wheel steering device according to the present invention will be described below.

In rear wheel steering control in an automobile, the amount of steering of the rear wheels is determined based on the amount of steering of the front wheels, vehicle speed, yaw rate, etc. In this embodiment, a controller (not shown) is connected to the main motor 136 and the sub motor 127, and the controller controls the steering amount of the front wheels, the vehicle speed,
Data such as yaw rate is input.

A drive signal based mainly on vehicle speed, yaw rate, etc. is sent to the sub-motor 127 from the controller, and in this case, the output shaft of the sub-motor 127 rotates by an amount necessary for control. The rotation of the sub motor 127 is controlled by gears 125,1
24, the fan-shaped gear 119 is rotated by a predetermined amount. Rotation of sector gear 119 causes rod pivot 110 to tilt by a predetermined amount.

A drive signal based on the amount of steering of the front wheels is mainly sent to the main motor 136 from the controller, and the output shaft of the main motor 136 rotates in response to the steering of the front wheels. When the output shaft of the main motor 136 rotates, the drive shaft 131 is also rotated via the bevel gears 135 and 134, thereby moving the drive member 130 by a predetermined amount in the axial direction. As the driving member 130 moves in the axial direction, the sector shaft lll rotates, and the rod member 103
Rotate the specified amount. Rotation of the rod member 103 causes the shaft 108 to rotate around the axis of the rod member 103, but when the rod pivot 110 is tilted, the shaft 108 rotates through the opening 110g of the inner cylinder 110b of the rod pivot 110. Because it rotates integrally with
It will be guided in a spiral motion around the rod member 103. That is, the shaft 108 rotates around the axis of the rod member 103 and is forced to move in the axial direction at the same time. Thereby, the rod member 103 also moves in the axial direction, and the steering rod members 106 and 107 are moved to turn the rear wheels by a predetermined amount.

Note that when the shaft 108 is rotated either above or below the horizontal plane passing through the axis of the rod member 103, the phase is positive (the steering direction of the front wheels and the steering direction of the rear wheels are the same), and the other side of the horizontal plane When the shaft 108 is on this horizontal plane, the phase is opposite (the front wheel steering direction and the rear wheel steering direction are opposite directions).Furthermore, when the shaft 108 is on this horizontal plane,
The amount of steering of the rear wheels is always zero.

Even if the amount of steering of the front wheels is a constant value, if the vehicle speed or the like varies, the amount of steering of the rear wheels must be changed accordingly. FIG. 6 is a graph showing the amount of axial movement of the rod member 103 relative to the rotation angle, that is, the rod stroke.

In FIG. 6, the angle θ is used as the amount of tilting of the rod pivot 110, that is, the amount indicating how much the rod pivot 110 is tilted with respect to the radial plane of the rod member 103, and the relationship θ1>θ2>θ3 is used depending on the size of the angle. This is what has become. As is clear from Fig. 6, even if the rotation angle of the rod member is the same, the angle θ,
It can be seen that there is always a larger axial movement in the case of angle θ3 than in the case of angle θ3. That is, the rod pivot 11
By controlling the zero tilting amount by the sub-motor 127, it is possible to finely control the amount of steering of the rear wheels relative to the amount of steering of the front wheels.

In addition, in the state shown in FIG. 1, the rod pivot 1
The tilting amount of No. 10 is zero, and in this state, the rear wheels are not steered at all regardless of the amount of steering of the front wheels.

[Effects of the Invention] According to the vehicle rear wheel steering device of the present invention that has been described in detail above, the sub motor tilts the guide member and the main motor rotates the rod member, so it is compact and compact. By using a rear wheel steering device, loss of drive torque can also be suppressed. Furthermore, since the torque to rotate the rod member is smaller than the torque to rotate the rod pivot, by using the main motor to rotate the rod member, the reduction ratio can be kept small, providing a highly efficient reduction mechanism. In addition, since the torque generated by the motor can be reduced, a large current is not required.

Furthermore, since you can freely set the angle of the rod pivot,
At high speeds where followability is required, the rod pivot angle is increased to reduce the overall reduction ratio, and at low speeds where high steering torque is required, the rod pivot angle is decreased to increase the overall reduction ratio. This increases the degree of freedom for optimal control of the vehicle's dynamic performance.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of a rear wheel steering device for a vehicle according to the present invention. FIG. 2 is a cross-sectional view taken along the line ■--■ in FIG. 3. FIG. 3 is a cross-sectional view taken along line mm in FIG. 1. FIG. 4 is a sectional view taken along line IV--IV in FIG. 1. FIG. 5 is a sectional view taken along line V-V in FIG. 4. FIG. 6 is a graph showing the amount of axial movement of the rod member 103 relative to the rotation angle, that is, the rod stroke. FIG. 7 is a cross-sectional view of a rear wheel steering device according to the prior art. [Description of symbols of main parts] 103...Rod member 108...Shaft 110...Rod pivot 127...
......Sub motor 136...Main motor Fig. 3 Rod rotation angle

Claims (1)

[Claims] 1. A main motor, a sub-motor, a rod member that steers the rear wheels by moving in the axial direction, and a guide that is tilted with respect to the axis of the rod member by the rotational force of the sub-motor. It consists of a guide member having a path, and an actuating member that protrudes radially from the rod member and is guided by the guide path, and the rod member rotates around its axis due to the rotational force of the main motor, thereby The actuating member is configured to rotate around the rod member along the guide path, and when the actuating member rotates around the rod member, the actuating member rotates around the rod member. a distance corresponding to the amount of rotation and the amount of tilting of the guide path of the guide member;
A rear wheel steering device for a vehicle, which steers the rear wheels by moving together with the rod member in the axial direction of the rod member.