JPH07291143A - Steering device for all wheel steering - Google Patents

Abstract

PURPOSE:To realize the all-wheel steering having the less slip angle even in any case of the same phase steering and the reverse phase steering, by dividing a tie rod for connecting the tie rod arms of the left and right wheels into two parts and connecting the first and the second parts by a connecting means which is slidable in the axial direction. CONSTITUTION:The left and right front wheels are installed in a rotatable manner on a front axle by each king pin through a knuckle which is integrally constituted of a tie rod arm, and the left and right tie rod arms are connected through a tie rod. In this case, the tie rod is divided, and the divided parts 2 and 3 are connected by a connecting means which can slide the divided parts 2 and 3 in the axial direction. As for the connecting means, a slider 5 which is installed in a turnable manner on a slider housing 4 is screwed with a male screw 2a installed on the divided part 2, and a pinion 6 installed on the output shaft of a stepping motor 7 is meshed with a gear 5b installed on the outer periphery of the slider 5, and the length in the axial direction of the tie rod 1 can be varied by the revolution of the pinion 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a knuckle which is integral with a tie rod arm and is rotatably mounted around a kingpin. Left and right wheels are rotatably attached to the knuckle, and both tie rod arms are connected by tie rods. The present invention relates to a steering device for steering all wheels.

[0002]

2. Description of the Related Art Steering devices are known in which all axles are rigid axles and all-wheel steering is possible.

Conventionally, in an all-wheel steering vehicle, there is no steering angle adjusting device and its control device for adjusting the steering angles of the left and right wheels. Therefore, for example, referring to FIG. 3, the in-phase steering is accurately performed in the low speed range. In order to do so, it is necessary to make the link system consisting of the line connecting the king pins 18, 18 and the left and right tie rod arms 15, 15 and the tie rod 11 connecting them parallel links. That is, the steering angle αR = αL = βR =
It becomes βL.

However, in this parallel link, when the anti-phase steering is performed as shown in FIG. 4, the front wheels and the rear wheels are in parallel with each other in the center of each wheel, the turning centers do not coincide, and the vehicle turns. Since the tire turns around the center C, a large slip angle is generated in the tire, which causes uneven wear of the tire.

Further, as shown in FIG. 5, the tie rod 1 having a tie rod interval lt shorter than the kingpin interval lk so that a slip angle does not occur in the tire during reverse phase.
As shown in FIG. 6, the steering angles of the left and right wheels are different in the case of Nos. 2 and 12a, so that a large slip angle occurs in the tire, which causes uneven wear of the tire.
In this case, αR <αL and βR <βL.

[0006]

[Discussion] As a result of the above study, it has been found that by expanding and contracting the length of the tie rod, it is possible to provide an all-wheel steering system with a small slip angle in both in-phase steering and anti-phase steering.

Therefore, it is an object of the present invention to provide an all-wheel steering steering device which makes the slip angle zero in all-wheel steering.

[0008]

According to the present invention, a knuckle integrated with a tie rod arm is rotatably attached around a kingpin, and left and right wheels are rotatably attached to the knuckle and both tie rod arms are tie rods. In the connected steering device for all-wheel steering, each tie rod is divided into two and is composed of a first portion and a second portion, and the first portion and the second portion can slide in the axial direction. It is connected by various connecting means.

Further, the connecting means is provided with a male screw on the first portion of the tie rod, a slider having a female screw to be engaged with the male screw, the slider is rotatably attached to the slider housing, and the slider is attached. A gear is provided on the outer circumference of the stepping motor, and a stepping motor having a pinion meshing with the gear is provided. The stepping motor is attached to the slider housing.

A controller for controlling the stepping motor is provided, and in the case of two-wheel steering, the controller uses a signal from a steering angle sensor for detecting the turning angle of each wheel, and the left and right wheel center extension lines and the rear wheel center extension line. The initial angle of the tie rod arm is set so that it matches the wheel axis.
When all-wheel steering is in reverse phase, the initial angle of the tie rod arm is set so that the axis running straight from the center of gravity of the vehicle to the center of the vehicle and the extension lines of the centers of the front, rear, left, and right wheels coincide. When the wheels are in the same phase, it has a function to set the initial angle of the tie rod arm so that all the wheels are in parallel.

[0011]

[Description of Operation and Effects] Since the present invention is configured as described above, in the case of two-wheel steering (2WS), the left and right front wheel center extension lines intersect with the rear wheel axis at one point by a signal from the controller. The initial angle of the tie rod arm is determined so that the length of the tie rod constituted by the first portion and the second portion is determined by the connecting means, and the tie rod arm operates similarly to a general 2WS vehicle.

In the all-wheel steering in-phase mode, the right and left front wheels detect, for example, the right wheel rudder angle by the rudder angle sensor, the controller determines the initial angle of the tie rod arm, and calculates the left wheel rudder angle for control. A signal is sent to the connecting means, and the slider is driven by the stepping motor and pinion of the connecting means until the left wheel reaches the calculated steering angle (same as the right wheel).
The tie rod composed of the first part and the second part is extended.

As for the relationship between the front and rear wheels, the front and rear right wheels are steered in the same direction by the same steering angle by the conventional mode switching device. And the left and right rear wheels are the same as the front wheels,
The steering angle of the right wheel is detected, and the control signal is sent to the connecting means,
The tie rod is extended until the steering angles of the left and right wheels of the rear axle are equal.

In the all-wheel steering reverse phase mode, the steering angle sensor detects the steering angle of the right front wheel, the controller determines the initial angle of the tie rod arm, calculates the steering angle of the front left wheel, and the control signal The tie rod composed of the first portion and the second portion is sent to the connecting means and the slider is driven by the stepping motor and the pinion of the connecting means until the left wheel reaches the calculated steering angle.

In this case, the controller has a function of controlling so that the instantaneous turning centers of the front, rear, left, and right wheels are aligned with a point on the axis orthogonal to the center of the vehicle from the center of gravity of the vehicle. As for the relationship between the front and rear wheels, the rear wheels are steered in the opposite direction by the mode switching device of the prior art, and the length of the tie rod is controlled by the signal from the controller as described above.

Therefore, the slip angle of the tire is controlled to be zero in all cases.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a reverse-phase mode in a four-wheel steering (4WS) steering device (plan view).
3 and the left front wheel 64 are tie rod arms 15 and 1 on the front axle (not shown) by king pins 18 and 18, respectively.
5 is rotatably attached via a knuckle integrally formed with the tie rod 5, and the tie rod arms 15 and 15 are connected by a tie rod 1, and the tie rod 1 has a connecting means described later.

The steering arm 5 is attached to the knuckle.
8 is fixed, and its steering arm 58 is connected to the pitman arm 54 of the steering gear box 52 via the drag link 56.
A steering wheel 50 is attached to the. The relay link 60 of the conventional mode switching device 40 is connected to the steering arm 58, and the relay link 60 is connected to the steering arm 58a of the right rear wheel 65.
a is connected via a power cylinder 62. Further, like the front wheels, the rear wheel tie rod arms 15a, 1
5a are connected by a tie rod 1a.

FIG. 2 shows the connecting means of the tie rods 1 and 1a, the first part 2 of which is provided with a male screw 2a,
A female screw 5a provided at one end of the slider 5 is screwed into the male screw 2a, and the outer periphery thereof is rotatably supported and positioned by the slider housing 4 via a radial thrust bearing 8 and is positioned at the other end of the slider 5. Is provided with a gear 5b, the end of which is axially supported by a housing retainer 4a via a bearing 9, and the end of the first portion 2 is supported by a bush 5c provided on the inner circumference of the gear 5b. .

A protrusion 4b having an internal thread is provided at the end of the housing retainer 4a, one end of the second portion 3 of the tie rod is screwed, and fixed by a lock bolt provided in the hole 4c. A stepping motor 7 having a pinion 6 that meshes with the gear 5b is attached to the retainer 4a.

Referring also to FIG. 1, the stepping motor 7 is connected to the controller 30 by an electric circuit, and the controller 30 is an electric circuit and the steering angle sensor 2 is connected.
0, the mode switching device 40, and the stepping motor 7 of the tie rod 1a for the rear wheel.

Reference numeral 2b represents a rubber boot.

Therefore, first, the controller 30 sets the reverse phase mode and sends a signal to the mode switching device 40.
The rod of the power cylinder 62 is pulled in to make it in a reverse phase, and the controller 30 calculates the steering angle of the left front wheel by the signal from the steering angle sensor 20 provided on the right front wheel, and sends the signal to the stepping motor 7 of the connecting means of the tie rod 1. The length of the tie rod 1 so that the left front wheel faces the turning center C, and then the tie rod 1a so that the left rear wheel faces the turning center C.
A signal is sent to the stepping motor 7 of the connecting means to adjust the length of the tie rod 1a.

In this case, the steering angle of the right front wheel is αR, the steering angle of the left front wheel is αL, the steering angle of the right rear wheel is βR, and the steering angle of the left rear wheel is βL.
Then, αR <αL and βR <βL.

Therefore, a slip angle does not occur in the tire and uneven wear does not occur.

During 4WS in-phase steering, the mode switching device is set to in-phase steering, and the steering angle of the right front wheel is detected by the steering angle sensor 2
0 is detected, and a signal is sent from the controller 30 so that the steering angles of all the wheels become equal, and the lengths of the front and rear tie rods are adjusted by the connecting means. In this case, αR = αL = βR =
It becomes βL and no slip angle occurs in the tire (Fig. 3).

[0028]

Since the present invention is constructed as described above, it has the following excellent effects.

(1) In the case of reverse-phase steering at 4WS, the extension line of the center of the four wheels coincides with a point on the line perpendicular to the center of the vehicle from the center of gravity of the vehicle, so that the tire slip angle does not occur.

(2) In the case of in-phase steering at 4WS, since four wheels are steered in the same direction and at the same steering angle, no tire slip angle occurs.

(3) In the case of 2WS, control is performed so that the center extensions of the left and right front wheels coincide with one point on the axis of the rear wheels, as in a general 2WS vehicle.

(4) Therefore, the tire does not wear unevenly.

[Brief description of drawings]

FIG. 1 is an overall configuration plan view of a 4WS device (in a reverse phase mode) showing an embodiment of the present invention.

FIG. 2 is a side sectional view showing the connecting means of FIG.

FIG. 3 is a diagram showing an example in which prior art in-phase steering is emphasized.

FIG. 4 is a diagram showing a state at the time of reverse-phase steering of the conventional technique shown in FIG.

FIG. 5 is a diagram showing an example where prior art reverse phase steering is emphasized.

6 is a diagram showing a state at the time of in-phase steering of the conventional technique shown in FIG.

[Explanation of symbols]

 1, 1a ... Tie rod 2 ... 1st part 2a ... Male screw 3 ... 2nd part 4 ... Slider housing 4a ... Housing retainer 5 ... Slider 5a ... Female screw 5b ... Gear 6 ... Pinion 7 ... Stepping motor 8 ... Radial thrust bearing 9 ... Bearings 15 and 15a ... Tie rod arm 20 ... Rudder angle sensor 30 ... Controller 40 ... Mode switching device 52 ... Steering gear box 54 ... Pitman arm 56 ... Drag link 58 ... Steering arm 60, 60a ... Relay link 62 ... Power cylinder

Claims (3)

[Claims] 1. A steering device for all-wheel steering, wherein a knuckle integrated with a tie rod arm is rotatably mounted around a kingpin, left and right wheels are rotatably mounted on the knuckle, and both tie rod arms are connected by tie rods. In each of the above, each tie rod is divided into two and is configured by a first portion and a second portion, and the first portion and the second portion are connected by an axially slidable connecting means. Steering device for all-wheel steering. 2. The connecting means is the first of the tie rod.
Is provided with a male screw, a slider having a female screw to be screwed with the male screw is provided, the slider is rotatably attached to the slider housing, and a gear is provided on the outer periphery of the slider, and a pinion meshing with the gear is provided. The steering device for all-wheel steering according to claim 1, further comprising a stepping motor, wherein the stepping motor is attached to the slider housing. 3. A controller for controlling the stepping motor is provided, and in the case of two-wheel steering, the controller uses a signal from a steering angle sensor for detecting a turning angle of each wheel, and the left and right wheel center extension lines and the rear wheel center extension line. The initial angle of the tie rod arm is set so that the wheel axes coincide with each other, and when all-wheel steering is in the opposite phase, the axis running straight from the center of gravity of the vehicle to the center of the vehicle and the center of each of the front, rear, left, and right wheels. The initial angle of the tie rod arm is determined so as to coincide with the extension line, and has a function of determining the initial angle of the tie rod arm so that all the wheels are parallel when all the wheels are in steering.
The steering device for all-wheel steering according to [4].