JP2937742B2 - Steering device for all-wheel steering - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a knuckle integral with a tie rod arm which 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. The present invention relates to a steering device for all-wheel steering.

[0002]

2. Description of the Related Art There is known a steering apparatus 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 for adjusting the steering angles of the left and right wheels and a control device therefor. For example, referring to FIG. 3, in-phase steering is accurately performed in a low speed range. For this purpose, it is necessary that the link system composed 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 these lines be parallel links. That is, the steering angle αR = αL = βR =
βL.

However, when the parallel link performs reverse phase steering as shown in FIG. 4, the center of each wheel is parallel to the front wheel and the rear wheel is parallel to each other, the turning centers do not coincide, and the vehicle turns. Since the tire turns around the center C, a large slip angle occurs in the tire, causing uneven wear of the tire.

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

[0006]

[Knowledge] As a result of the above examination, it has been found that an all-wheel steering device with a small slip angle can be obtained in both cases of in-phase steering and reverse-phase steering by extending and contracting the length of the tie rod.

Accordingly, an object of the present invention is to provide a steering apparatus for all-wheel steering that makes the slip angle zero in all-wheel steering.

[0008]

According to the present invention, a knuckle integral 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 tie rods. In the connected steering apparatus for all-wheel steering, each tie rod is divided into two parts to constitute a first part and a second part, and the first part and the second part are slidable in the axial direction. The connecting means is provided with a male screw on a first portion of the tie rod, a slider having a female screw screwed with the male screw, rotatably mounting the slider to a slider housing, and A gear is provided on the outer periphery of the slider, and a stepping motor having a pinion that meshes with the gear is provided. And a controller for controlling the stepping motor. The controller receives a signal from a steering angle sensor that detects a steering angle of each wheel. The initial angle of the tie rod arm is determined so that the axis perpendicular to the center of the vehicle coincides with the extension of the center of each of the front, rear, left, and right wheels, and when all wheels are in phase, all wheels are parallel. To determine the initial angle of the tie rod arm.

[0009]

[0010]

[0011]

Description of the operation and effect 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 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 formed by the first portion and the second portion is determined by the connecting means, and the tie rod operates similarly to a general 2WS vehicle.

In the all-wheel steering in-phase mode, the left and right front wheels detect, for example, the right wheel steering angle by a steering angle sensor, the controller determines the initial angle of the tie rod arm, calculates the steering angle of the left wheel, and performs control. A signal 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 (same as the right wheel).
The tie rod constituted by the portion and the second portion is extended.

The relationship between the front and rear wheels is such that the front and rear right wheels are steered by the same steering angle in the same direction by the conventional mode switching device. And the left and right rear wheels, like the front wheels,
Detecting the steering angle of the right wheel, a control signal is sent to the connecting means,
The tie rod is extended until the steering angles of the right and left rear wheels become equal.

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

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

Accordingly, 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 reversed-phase mode in a four-wheel steering (4WS) steering apparatus (plan view).
3 and the left front wheel 64 are connected to a front axle (not shown) by king pins 18 and 18, respectively.
The tie rods 15 and 15 are rotatably mounted via a knuckle integrally formed with the tie rod 5. The tie rods 15 and 15 are connected by a tie rod 1, and the tie rod 1 has a connecting means described later.

The knuckle has a steering arm 5.
The steering arm 58 is fixedly connected to the pitman arm 54 of the steering gear box 52 via a drag link 56, and the gear box 52
Is mounted with a steering wheel 50. The steering arm 58 is connected to a relay link 60 of the mode switching device 40 of the related art, and the steering arm 58a of the right rear wheel 65 is connected to the relay link 60.
a is connected via a power cylinder 62. Further, similarly to the front wheels, the tie rod arms 15a, 15a, 1
5a is connected by a tie rod 1a.

FIG. 2 shows the connecting means of the tie rods 1 and 1a, wherein the first part 2 is provided with a male screw 2a,
A female screw 5a provided at one end of the slider 5 is screwed to 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 rotatably 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 periphery of the gear 5b. .

A protrusion 4b having a female thread is provided at an end of the housing retainer 4a. One end of the second portion 3 of the tie rod is screwed into the tie rod, and is fixed by a lock bolt provided in a hole 4c. A stepping motor 7 to which a pinion 6 that meshes with the gear 5b is mounted is mounted on 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 connected to the steering angle sensor 2 by an electric circuit.
0, the mode switching device 40, and the stepping motor 7 of the rear wheel tie rod 1a.

Reference numeral 2b denotes a rubber boot.

Therefore, first, the controller 30 sets the anti-phase mode and sends a signal to the mode switching device 40.
The controller 30 calculates the steering angle of the left front wheel based on the signal from the steering angle sensor 20 provided on the right front wheel, and sends a signal to the stepping motor 7 of the connecting means of the tie rod 1 based on the signal from the steering angle sensor 20 provided on the right front wheel. 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, the relationship is αR <αL and βR <βL.

Therefore, no slip angle occurs in the tire, and uneven wear does not occur.

At the time of 4WS in-phase steering, the mode switching device is set to in-phase steering, and the steering angle of the right front wheel is determined by the steering angle sensor 2.
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 =
βL and no slip angle occurs in the tire (FIG. 3).

[0028]

The present invention has the following advantages because it is configured as described above.

(1) In the case of reverse phase steering with 4WS, the extension line of the center of the four wheels coincides with a point on a line perpendicular to the center of the vehicle from the center of gravity of the vehicle, so that no tire slip angle occurs.

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

[0031]

(3) Therefore, there is no uneven wear of the tire.

[Brief description of the 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. 1;

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 related art shown in FIG. 3;

FIG. 5 is a diagram showing an example in which prior art reverse-phase steering is emphasized.

FIG. 6 is a diagram showing a state at the time of in-phase steering of the related art shown in FIG. 5;

[Explanation of symbols]

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

──────────────────────────────────────────────────の Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B62D 7/14

Claims (1)

(57) [Claims] A knuckle integral 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. , Each tie rod is divided into two parts to constitute a first part and a second part, and the first part and the second part are connected by connecting means slidable in the axial direction. Providing a male screw on a first portion of the tie rod, providing a slider having a female screw to be screwed with the male screw, rotatably attaching the slider to a slider housing,
A gear is provided on the outer periphery of the slider, and a stepping motor having a pinion that meshes with the gear is provided.The stepping motor is configured to be mounted on the slider housing, and a controller that controls the stepping motor is provided. According to the signal from the steering angle sensor that detects the steering angle of each wheel, in the case of all-wheel steering reverse phase, the axis perpendicular to the center of the vehicle from the center of gravity of the vehicle and the center of each of the front, rear, left and right wheels are extended. The initial angle of the tie rod arm is determined so that the lines coincide with each other, and when all wheels are in phase, all wheels are provided with a function of determining the initial angle of the tie rod arm so that all wheels are parallel. Steering device for steering.