JPH0221340Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a steering device for an automobile that drives a steering mechanical system of a steered wheel by a driver's rotational operation of a steering wheel.

This type of steering device for automobiles is of the front-wheel steering type, except for special vehicles, but if it is changed to a four-wheel steering type, the turning radius can be reduced, or alternatively, the wheelbase can be lengthened to improve ride comfort. You can make it better. However, when this system is actually applied to ordinary cars, there are problems in terms of cost and weight if the steering system is a conventional fully mechanical or hydraulic type.

Therefore, an object of the present invention is to provide a four-wheel steering type automobile steering device that is lightweight and inexpensive.

In order to achieve this objective, the present invention provides a steering mechanical system operated by an associated electric motor for each of the front and rear wheels, and a steering wheel that is mechanically independent and rotatably operated from the steering mechanical system. , a steering command signal generator that outputs a steering command direction signal and a steering command angle signal in response to the rotation of the steering wheel, thereby causing the electric motor to drive and control the steering mechanical systems of the front wheels and the rear wheels, respectively; A reaction force actuator is attached to a rotating mechanism that is rotationally driven by the steering wheel so as to apply a reaction force in the opposite direction to the rotational operation of the wheel. and reaction force drive control means for driving and controlling the reaction force actuator to generate a corresponding reaction force.

As a result, when the steering wheel independent of the steering system is rotated, the front wheel side and rear wheel side electric motors respond to the steering command direction signal and steering command angle signal output from the steering command signal generator to control the associated steering wheel. Drive and control the system. At this time, the reaction force actuator applies a reaction force to the steering wheel that increases accordingly as one or both of the steering angle and vehicle speed increases.

Next, the present invention will be explained based on the illustrated embodiments.

In FIG. 1, reference numeral 1 denotes a conventional front wheel side steering mechanical system using, for example, a rack and pinion type steering gear, and an electric motor 3 is attached to the steering gear 2. As shown in FIG. 1' is a similar mechanical steering system on the rear wheel side, and another electric motor 3' is attached to the steering gear 2', and the rear wheels are equipped with a propeller shaft 4, a differential gear 5, and a universal joint 6. and a drive shaft 7 in a known manner. 10 is a steering column attached to a dart board, for example, and includes a steering wheel 11, a gear system 12 as a rotating mechanism interlocked with the steering wheel 11, and a steering command angle signal and a steering command direction signal that rotate in conjunction with the gear system. A steering command signal generator 13 outputs a steering command signal a, and a steering wheel 11 that is about to rotate is configured to increase or decrease the steering force required by the driver in response to steering conditions such as wheel deflection angle and vehicle speed. It is provided with a DC motor 14 which together with a gear system 12 constitutes a reaction force actuator. Reference numeral 20 denotes a reaction force drive control circuit, which reduces the centripetal acceleration generated on a curve by steering wheel operation to a certain level or less with respect to the steering command angle output from the steering command signal generator 13 and the vehicle speed v detected by the vehicle speed sensor 21. In order to do this, for example, a drive input corresponding to v ² is applied to the DC motor 14 with a polarity that is a reaction force of the steering wheel 11 so as to generate a reaction force proportional to v ² . The steering command signal a is conveyed by an electric wire or an optical fiber provided with a photoelectric converter at the transmitting and receiving ends. 30 and 30' operate the electric motors 3 and 3', respectively, according to the steering command angle and the steering command direction. This is a drive control circuit. Note that for the same steering command signal a, the drive control circuits 30, 3
0' and electric motors 3, 3' are in a relationship to steer the steering mechanical systems 1, 1' in opposite directions as shown in FIG. It exhibits an Atsukerman-Giant geometry of β.

If the steering command signal generator 13 is a potentiometer that outputs a DC voltage whose polarity changes depending on the direction of rotation of the steering wheel 11 with respect to a reference unit and whose level changes depending on the amount of rotation, the signal shown in FIG. As shown, the reaction force drive control circuit 20 is, for example, entirely of an analog circuit type, and includes a squaring section 2 that squares the v signal supplied from the power generating vehicle speed sensor 21.
2 and the absolute value of the steering command angle signal, a multiplication unit 23 that calculates v ² from the absolute value of the steering command angle signal, a rotation direction identification unit 24 that identifies the direction of change of the steering command angle signal, and outputs a drive input with a polarity according to the identification result to the DC motor 14. It consists of a power amplifying section 25. On the other hand, the electric motors 3 and 3' are DC servo motors with a tachometer, and each motor is a potentiometer-type steering angle that outputs a DC voltage whose polarity changes depending on the steering direction and whose level changes according to the steering angle. The sensor is attached, and the drive control circuits 30 and 30' consist of a comparison section between the steering command angle and the steering angle' according to a well-known servo control method, and a power amplification section that amplifies the power of the error signal with the addition of tachodynamic feedback. Configure. This results in
When the driver operates the steering wheel 11, the steering signal generator 13 sends a steering command signal a corresponding to the steering command angle with a polarity according to the steering direction to the drive control circuits 30, 30' through electric wires or optical fibers.
Therefore, a large drive input is supplied to the electric motors 3, 3', which corresponds to the error angle with respect to the steering angle', and due to the absence of tachodynamic feedback at first.
The steering mechanical systems 1, 1' quickly respond to this and steer the front wheels and rear wheels to deflection angles α and β, respectively, so that the steering angle 'coincides with the steering command angle. At this time, the steering command signal a is simultaneously supplied to the reaction force drive control circuit 20 shown in FIG.
The drive input of the magnitude corresponding to v ² is DC motor 1.
4, and applies a reaction force to the steering wheel 11 that increases or decreases depending on the steering condition.

If the steering command signal generator 13 is a 2-bit rotary encoder that generates a pulse for each unit rotation amount to identify the direction of rotation of the steering wheel 11, the electric motors 3 and 3' may be replaced with step motors. , drive control circuit 30,3
0' is composed of a direction identifying section that provides a rotational direction signal to this step motor, and a pulse driving section.
However, the aforementioned DC servo motor can also be used using a reversible counter that counts input pulses and its D/A converter. On the other hand, the reaction force drive control circuit 20 can also utilize a microcomputer as shown in FIG. That is, the reversible counter 26
The steering command angle is maintained by counting the pulse of 1 bit of the steering command signal a, and the flip-flop 27 uses one of the 2-bit steering command signal a as data and the other as a clock, and stores the data at the rising edge of the clock. The rotation direction of the steering wheel 11 is identified by determining 1 and 0. The vehicle speed sensor 21 in this case is of a photoelectric pulse type that generates pulses whose pulse rate changes depending on the vehicle speed. The microcomputer 28 takes in pulses for a unit time from the vehicle speed sensor 21 at predetermined intervals, sets the counted value as the vehicle speed v, and also takes in the steering command angle, which is the counted value of the reversible counter 26, to calculate the reaction force, for example. The calculation of v ² is performed as described above. The drive section 29 is
A drive input corresponding to v ² is supplied to the DC motor 14 with a polarity corresponding to the direction of rotation of the steering wheel 11 identified by the flip-flop 27 .

FIG. 5 shows a modification of the rear wheel drive control circuit 30' when the electric motors 3, 3' are DC servo motors. The signal is supplied to the amplifier section 32, but when the switch 33 is switched, the input to the comparator section 31 is always zero, and the rear wheels are locked at the reference position as shown in FIG. 6, resulting in a front wheel steering system. That is, the modes shown in FIG. 2 and FIG. 6 can be arbitrarily selected using a control mode changeover switch provided in the driver's seat.

FIG. 7 shows yet another modification of the drive control circuits 30, 30', in which the steering command angle is corrected in accordance with the vehicle speed v and the stress of the steering mechanical system 1. That is, as shown in the figure, the steering mechanical system 1,
Strain in strain gauges 34 functioning as external load sensors attached to arms 9, 9' connected to knuckle arms 8, 8' of 1' is detected as an external load signal F by an associated bridge circuit 35. This F is the stepping force in response to the centrifugal force when the vehicle turns, and in order to increase the cornering force when turning a corner at high speed, the slip angle of the wheels is increased to balance the posture. need to take. On the other hand, as the vehicle speed v increases, it is necessary to prevent the wheels from swinging too much. Therefore, the correction unit 36 performs a correction such that the steering correction command angle ″=f(,v,F) is made so that for the same steering command angle, when v becomes larger, the apparent value is made smaller, and when F becomes larger, it is made larger.
If the electric motors 3 and 3' are DC servo motors, the drive section 38 amplifies the power of the error signal with respect to the steering angle' obtained by the comparator 37. Each of these parts 36 and 37 can be of an analog type, but
A microcomputer capable of particularly high-speed calculations may be used in common with the microcomputer 28 in FIG. 4 or separately. That is, in FIG. 8, the microcomputer 40 is connected to the reversible counter 2 in FIG.
6 is periodically taken in as a steering command angle, and the steering wheel 1 is determined based on the output signal of the flip-flop 27 shown in FIG.
The steering direction with respect to the reference position of 1 is determined. Similarly, the vehicle speed sensor 21 is periodically
The vehicle speed v is calculated by taking input pulses from
F) respectively, and the associated drive units 41, 4
1', a steering correction command angle corresponding to the steering command direction is supplied.

As described above, according to the present invention, the steering mechanical systems on the front and rear wheels are each driven by an electric motor, and the steering wheel is connected to the steering wheel equipped with a reaction force device that applies a reaction force that increases or decreases depending on the steering condition via an electric wire or an optical fiber. By controlling the drive, it is possible to realize an electric four-wheel steering type power steering device without a steering shaft that is safe and practical in terms of actual steering wheel operation. In particular, even if it is a four-wheel steering system, the overall configuration of the power steering system is
Simpler and cheaper than hydraulic type. The advantages of not having a steering shaft, such as improved assembly work efficiency, improved usability of the engine compartment, and increased freedom in body and interior design, are more effectively demonstrated by the electric type.

[Brief explanation of drawings]

Figure 1 shows an example of the basic configuration of a four-wheel steering type steering device according to the present invention, Figures 3 to 5, and Figures 7 and 8 show more specific examples of the configuration, and Figures 2 and 6 show steering modes according to the present invention. An explanatory diagram is shown. 1, 1'... Steering mechanical system, 2, 2'... Steering gear, 3, 3'... Electric motor, 10... Steering column, 11... Steering wheel,
12...Gear system, 13...Steering command signal generator,
14...DC motor.

Claims (1)

[Scope of Claim for Utility Model Registration] A steering mechanical system operated by an associated electric motor is provided for each of the front and rear wheels, and a steering wheel is mechanically independent of the steering mechanical system and is rotatably operated; a steering command signal generator that outputs a steering command direction signal and a steering command angle signal in response to rotation of a wheel, thereby causing the electric motor to drive and control the steering mechanical systems of the front wheels and the rear wheels, respectively; a reaction force actuator attached to a rotating mechanism rotationally driven by the steering wheel so as to apply a reaction force in a direction opposite to the rotational operation of the steering wheel, and receiving a steering direction, a steering angle, and a vehicle speed signal as input;
A steering device for a motor vehicle, comprising: reaction force drive control means for driving and controlling the reaction force actuator so as to generate a reaction force corresponding to a steering angle and a vehicle speed.