JPH01136876A - Four-wheel steering device - Google Patents

Abstract

PURPOSE:To electrically carry out the operation responsiveness of front and rear wheels by providing an electric motor which is electronically controlled by the input signals of a front wheel steering angle sensor, a steering angular velocity sensor, a vehicle speed sensor, etc., and a rear wheel steering device which is driven by this motor. CONSTITUTION:A steering-angle/angular-velocity sensor 102 in response to a steering angle and a vehicle speed sensor 113 in response to vehicle speed are provided on a steering handle 120. A rear wheel steering device 121 which is driven by an electric motor 109 is connected to rear wheels 106 via a tie rod 107 and steering arms 108. The electric motor 109 is controlled by an electronic control device 111 in accordance with a vehicle speed and the steering angle and angular velocity of front wheels. The speed reduction of the electric motor 109 is carried out by means of a reducing gear 122 and its driving force is transmitted to a rear wheel driving device.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a four-wheel drive system for front and rear wheels of an automobile.

(Prior art) As shown in Japanese Patent Publication No. 60-44185, there is a mechanical four-wheel steering device that mechanically connects the front and rear wheels and steers the rear wheels in the same or opposite phase according to the steering angle of the front wheels. is publicly known.

Furthermore, as shown in Japanese Unexamined Patent Publication No. 59-6171, there is a detector that detects the turning direction and actual steering angle of the front wheels, and a control is performed when the actual steering angle of the front wheels reaches a set angle or more based on the detection signal of the detector. A control mechanism that emits a signal, a hydraulic cylinder of a rear wheel steering mechanism that is operated via a servo valve or a switching valve controlled by the control signal, and an actual steering angle of the front wheels that exceeds a set angle by the operation of the hydraulic cylinder. A hydraulic four-wheel drive system is also known which includes the rear wheel steering mechanism described above, which steers the rear wheels in the opposite direction to the actual steering direction of the front wheels when the front wheels reach the actual steering direction.

Furthermore, as shown in Japanese Patent Application Laid-Open No. 59-128052,
A steering gear mechanism connected to the rear wheel tie rod,
a power cylinder that provides a steering assist force to a rear wheel tie rod; a control valve that controls the supply of pressure oil to the power cylinder according to input to the steering gear mechanism; and a motor that drives an input shaft of the steering gear mechanism. The controller is configured such that at least a signal from a front wheel steering angle sensor is input manually.

An electrohydraulic four-wheel rocking device is also known, which is configured to control the motor so as to steer the rear wheels in accordance with the front wheel steering angle.

(Problems to be Solved by the Invention) In the above-mentioned prior art, the mechanical four-wheel drive system determines the steering angle of the rear wheels in relation to the steering angle of the front wheels, and takes a correlation with the vehicle speed. In order to achieve accurate response, reducing the gap increases friction, resulting in poor smoothness, the mechanism is complicated and costly, and connecting rods for the front and rear wheels are required, which means that the road surface is attached to the bottom of the vehicle. A space is required to arrange the connecting rod so as not to hit it, and there is a problem in that the connecting rod can hit the unevenness of the road surface and bend, resulting in poor connection between the front and rear axles.

Hydraulic four-wheel shaking devices and electrohydraulic four-wheel drive devices require space for pumps, valves, and piping that respond to vehicle speed, and have a problem in that they have many components and are expensive.

(Means for Solving the Problems) The present invention aims to solve the above problems, and includes an electric motor that is electronically controlled by input signals such as a front wheel steering angle, a steering angular velocity, and a vehicle speed sensor. The present invention is characterized in that it includes a speed reducer that is driven by the speed reducer, and a rear wheel steering device that is connected to the speed reducer.

Hereinafter, the illustrated embodiment will be specifically explained. A known front wheel steering device 101 of manual or power steering is disposed on the front wheels 103, 103'. Handle 1
20 includes a steering angle and angular velocity sensor 102 that responds to the steering angle;
A vehicle speed sensor 113 is provided for vehicle speed response. A rear wheel steering device 121 that is operated by an electric motor is connected to the rear wheel 106 via a tie rod 107 and a knuckle arm 108 . The electric motor 109 is controlled and supplied with electric current supplied from a battery by an electronic control device 111 according to the vehicle speed, front wheel steering angle, and angular velocity, and is opened and operated.

The rear wheel steering device 121 also includes a centering spring 13,
A position sensor 110 is provided to determine the rear wheel steering position 1.
21 in a neutral (straight ahead) position, and also to reliably follow the steering direction of the front wheel steering device 1lo1 and the direction steered by the vehicle speed.

The electric motor is decelerated and power is transmitted by the reduction gear 122, and is independent from the rear wheel steering device 121, so that it can be freely assembled around the longitudinal axis of the rear wheel steering device, in parallel, or at right angles. It has become.

Next, the effect will be explained. When the steering wheel 120 is operated to the right, the front wheel steering device 101 rotates the operating tie rod 104 to the left and the knuckle arm 105 to the right using a known method, thereby turning the front wheels 103° 103' to the right and moving in a predetermined direction. Can be steered.

On the other hand, the rear wheel steering device 121 is operated by the electronic control device 1 based on the signal from the steering angle and angular velocity sensor 102 attached to the column shaft of the steering wheel 120 and the signal from the vehicle speed sensor 113.
The predetermined pattern output calculated in step 11 is supplied to an electric motor 109 attached to the rear wheel steering device, and the predetermined rotation direction and rotation amount are controlled. An example of rear wheel steering amount is shown in the fourth example.
As shown in the figure.

That is, at low speeds, the front wheels can be steered in the opposite direction, and at high speeds, the front wheels can be steered in the same direction, thereby reducing the turning radius of the actual vehicle and improving high-speed running stability, respectively.

cAO range at all low speeds) The rotational output of the electric motor is transmitted to the planetary roller reducer 91 and bevel gear shaft 94, the direction is changed by the bevel gear 32.35, and the key 36 transfers it to the pinion 30, which then engages with the pinion 30. The signal is transmitted to the rack 1 that is currently in use. The axial load transmitted to the rack 1 further compresses the pre-compressed and positioned centering spring 13, moving the rack to the left in FIG. Rotate the rear @10G to the left through 108.

At this time, the position sensor 110 captures the amount of movement of the rack and sends feedback to the electronic control unit 111 in a predetermined direction.
You can check the quantity.

The electric motor 109 has its output controlled according to the steering angle and angular velocity of the front wheels in correspondence with the centering spring 13 during steering and when returning the steering wheel, and is larger than the spring force of the spring 13 when steering and smaller than the spring force of the spring 13 when returning the steering wheel. It looks like this.

On the other hand, the set load of the centering spring 13 is sufficient against disturbances from the road surface, but when an even larger input occurs, an output is supplied to the electric motor 8 due to the input from the position sensor 110.

In order to prevent delay in operation due to the responsiveness between the front and rear wheels in the engagement between the output shaft 80 of the electric motor and the rack 1, a planetary roller reducer 91 is used to reduce the speed from the electric motor.
In addition, the motor shaft 1 is fitted with the inner diameter part of the input shaft 90, and the inner diameter part of the output shaft 96 and the bevel gear shaft 94 are fitted with a small gap tessellation. On the other hand, the bevel gear shaft is rotatably supported by a ball bearing 97 and a needle bearing 98.

The meshing of the bevel gears 32 and 35 can be adjusted using an adjustment screw 46 so that they mesh with each other with a small gap. The rack 1 and pinion 3o are supported by a pre-compressed spring 11 so as to mesh with each other without any gap.

When the vehicle speed exceeds a predetermined value, the output signal from the vehicle speed sensor switches the phase from the opposite phase to the same phase, and steering is performed in the same manner as described above.

(Effects) According to the present invention, there is provided an electric motor that is electronically controlled by input signals such as front wheel steering angle, steering angular velocity, and vehicle speed sensor; - a reducer that is driven by the electric motor; Since it is equipped with a rear wheel steering device, the front wheel steering device (
Regardless of power, manual, etc., settings can be made to match the actual vehicle and each variable factor. In addition, the operational response of the front and rear wheels can be controlled electrically, and the backlash of the components, which is a negative factor, needs to be addressed only in the rear wheel steering system, resulting in low friction. A four-wheel steering device with good responsiveness can be obtained.

Furthermore, in response to disturbances from the road surface, the movement of the rear wheels can be controlled by the set load of a centering spring that is compressed in advance.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an embodiment of the present invention, Fig. 2 is a cutaway front view of essential parts of the rear wheel steering device shown in Fig. 1, and Fig. 3 is a line A-A in Fig. 2.
The side sectional view, FIG. 4, is a diagram showing the rear wheel steering angle and vehicle speed. 101... Front wheel steering device 102... Rudder angle sensor 103.103'... Front wheels 106, 106'
...Rear wheel 109...Electric motor 110...
Position sensor 111...Electronic control device 113...
・Vehicle speed sensor 120...handle 121・
...Rear wheel steering device 122...Deceleration device

Claims (1)

[Claims] The vehicle is characterized by being equipped with an electric motor that is electronically controlled by input signals such as front wheel steering angle, steering angular velocity, and vehicle speed sensor, a reduction gear driven by the electric motor, and a rear wheel steering device connected to the reduction gear. A four-wheel steering device.