JPH0711005Y2 - 4-wheel steering system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an all-electric four-wheel steering device that detects a steering wheel steering signal (front steering angle signal) of front wheels and steers rear wheels with a motor. .

[Prior Art] In the case of an all-electric four-wheel steering device that independently steers the rear wheels based on the steering angle of the front wheels (hereinafter referred to as the "front steering angle"), the reliability of the front steering angle signal is important. Ensuring this reliability greatly affects the safety of the vehicle.

As a device for improving the reliability of this front steering angle signal, a device using two potentiometers as front steering angle sensors has been proposed.

[Problems to be solved by the device]

However, when using two potentiometers,
It had the following drawbacks.

When affected by electromagnetic interference (EMI), both analog signals output from the potentiometer change. For example, as shown in FIG. 6, the output signals b1 and b2 or b1 and b2 'of the two potentiometers change in the same direction as indicated by arrows.

 It is difficult to find a straight ahead position during vehicle assembly inspection.

Further, in the conventional four-wheel steering system, the rear wheels may be steered in an arbitrary direction when the actuator, the drive circuit, or the like is abnormal.

[Means for Solving the Problems]

In order to solve such a problem, the present invention provides a four-wheel steering system having a controller for electrically steering the rear wheels based on the steering wheel angle and the vehicle speed. The column sensor installed in the vehicle to output the digital signal of, the front steering angle sensor that outputs the front steering angle signal that changes in an analog manner according to the steering angle of the front wheel, the target rear wheel position and the current rear wheel. When the deviation from the position does not converge to the specified value within the specified time, the error processing means to stop the power supply to the rear wheel steering motor, the front wheel is in the straight ahead position, and the column sensor outputs a digital signal of a predetermined level. When outputting, it is checked whether the front steering angle signal is within the predetermined level range according to the instruction from the outside.If it is not within the predetermined level range, the reference value and the actual front steering angle signal The difference from the value An adjustment value storage means for storing the adjusted value and a front steering angle signal correction means for correcting an error included in the front steering angle signal output from the front steering angle sensor by the adjustment value stored in the adjustment value storage means are provided. It is a thing.

[Action]

In the four-wheel steering system according to the present invention, when the front wheels are in the straight traveling position and the column sensor outputs a digital signal of a predetermined level, the front steering angle signal has a predetermined level range in response to an instruction from the outside. If it is not within the predetermined level range, the difference between the reference value and the actual value of the front steering angle signal is stored as the adjustment value. The error contained in the front steering angle signal output from the front steering angle sensor is corrected by the stored adjustment value.

Further, when the deviation between the target rear wheel position and the current rear wheel position does not converge within the specified value within the regulation time, the power supply to the rear wheel steering motor is stopped.

[Embodiment] FIG. 2 is a block diagram showing a four-wheel steering system according to the present invention. In the figure, 1 is a front wheel steering system, 1a is a steering angle sensor, 1b is a column sensor, and 2 is an electric rear wheel. Steering device, 2a is a DC motor for steering rear wheels, 2b is a reduction gear, 2c is a steering angle sensor, 2d is a centering spring, 3 is a vehicle speed signal a, a front steering angle signal b, a rear steering angle signal c, an engine signal d. The controller 4 to which the column sensor signal f, the center set signal g, etc. are input, is a relay for supplying electric power to the motor 2a.

FIG. 1 is a system diagram showing the controller 3 of FIG. 2 in detail. In the figure, 5 is a CPU, 6 is an abnormality display lamp, 7 is a vehicle speed sensor, 8 is a front steering angle sensor, 9 is a rear steering angle sensor, 10 is a column sensor, 11 is a central set switch, 51
Is a convergence monitoring unit that outputs an error signal e when the deviation between the target rear wheel position and the current rear wheel position does not converge within the specified deviation within a specified time, 52 is an initial diagnosis and fail software unit, and 53 is a relay drive unit. Therefore, the convergence monitoring unit 51 and the relay drive unit 53 constitute error processing means. Also, 54 is a correlation check unit,
55 is an EEPROM, and 56 is an adjusting unit, and these 54 to 56, the column sensor 10 and the central set switch 11 constitute a front wheel steering angle correcting means. In FIG. 1, the same or corresponding parts as those in FIG. 2 are designated by the same reference numerals.

3 and 4 are configuration diagrams showing a part of the column, in which 12 is a photo interrupter section, 13 is a slit, and 14 is a slit.
Is a column cover, and 15 is a shield plate. The photo interrupter unit 12 and the shield plate 15 form a column sensor 10. The column sensor 10 outputs an "L" level signal when the slit 13 is in the photo interrupter unit 12. Output.

Next, the operation of one embodiment of the four-wheel steering system according to the present invention will be described with reference to FIGS. 1 and 5. The column sensor signal f output from the column sensor 10 and the front steering angle signal b output from the front steering angle sensor 8 are shown in FIG. Fifth
In the figure, P1 is the right lock position, P2 is the left lock position, and 17 to 19 are sections of the rotation angle 360 degrees of the potentiometer which is the front steering angle sensor 8, respectively. Line L in the middle of section 18
1 indicates the front steering angle when the vehicle travels straight (hereinafter referred to as "straight steering angle"). The level of the front steering angle signal b at this time is the level m1 and the level m2 as shown in FIG. Must be in between. However, the level of the front steering angle signal b may shift due to offset continuous noise, and if this is used as it is as a control signal, it is determined that the front wheels are steered even though the vehicle is actually traveling straight, and the rear wheels are also steered. It is very dangerous because it is worn out. In order to prevent this, the column sensor
10 is provided so that the column sensor signal f of “L” level is output when the front wheels are in the straight traveling position,
The controller 3 knows from the "L" level column sensor signal f that the front wheels are in the straight traveling position. In addition, in the column sensor signal f, there is an "L" level signal area at positions of 360 degrees to the right and left of the center line L1, and the reference values at this time are n1, n2 and 1, 2, respectively. .

Next, assembly and adjustment of the column sensor 10 will be described. As can be seen from the above, the column sensor 10
Adjusts the column sensor signal f to the “L” level while the vehicle is in a straight traveling state when it is mounted on the vehicle. When the center set switch 11 is turned on in this state, the center set signal g becomes "L" level and is input to the correlation check unit 54. As a result, the CPU 5 writes a signal obtained by A / D converting the front steering angle signal b in the EEPROM 55. In this case, if the level of the front steering angle signal b is not between the levels m1 and m2 shown in FIG. 5,
The front steering angle signal b is not written in the EEPROM 55, but the difference between the reference value at the front wheel straight-ahead position and the actual value of the front steering angle signal b is written in the EEPROM 55 as an adjustment value. By inputting the adjustment value written in the EEPROM 55 to the adjusting unit 56, the error contained in the front steering angle signal b output from the front steering angle sensor 8 is corrected, and the adjustment of the front steering angle sensor 8 itself is unnecessary. Therefore, it is possible to prevent the rear wheels from being steered regardless of the straight traveling position. Further, since the column sensor signal f is a digital signal and has a high threshold value, it has good noise resistance and the signal f itself is not affected by noise.

Further, the controller 3 has a fail-safe function, which will be described below. In the CPU 5, after setting a certain specified time, after outputting the drive signal to the rear wheel steering DC motor 2a, if the rear wheels do not converge in the target value direction even after the specified time has elapsed, the convergence monitoring unit 51 Outputs an error signal e to the initial diagnosis and fail soft section 52, and the initial diagnosis and fail soft section 52 controls the relay drive section 53 to relay 4
To turn off. As a result, the electric power supply to the motor 2a is stopped, and the rear wheels are returned to neutral by the centering spring 2d (see FIG. 2) and become 2WS. In addition, the initial diagnosis and fail software unit 52 displays the above-mentioned abnormality in the abnormality display lamp 6
Notify the driver by

[Effect of device]

As described above, according to the present invention, when the front wheels are in the straight traveling position and the column sensor outputs the digital signal of the predetermined level, the front steering angle signal is in the predetermined level range according to the instruction from the outside. If it is not within the predetermined level range, the difference between the reference value and the actual value of the front steering angle signal is stored as an adjustment value, and the stored adjustment value of the front steering angle sensor is stored. Since the error contained in the output front steering angle signal is corrected, it is not necessary to adjust the front steering angle sensor itself, and it is possible to prevent the rear wheels from being steered even in the straight traveling position.

Also, if the deviation between the target rear wheel position and the current rear wheel position does not converge within the specified value within the specified time, the power supply to the rear wheel steering motor is stopped. The effect is great such that the rear wheels can be prevented from being steered in an arbitrary direction.

[Brief description of drawings]

FIG. 1 is a system diagram showing a controller that constitutes the device shown in FIG. 2, FIG. 2 is a configuration diagram showing an embodiment of a four-wheel steering device according to the present invention, and FIGS. 3 and 4 are columns. 5 is a configuration diagram showing a part of FIG. 5, FIG. 5 is an explanatory diagram showing a column sensor signal and a front steering angle signal, and FIG. 6 is a diagram for explaining a defect in a conventional device. 1 ... front wheel steering device, 1a ... steering angle sensor, 1b ... column sensor, 2 ... electric rear wheel steering device, 2a ... DC motor, 2b ... reduction gear, 2c ... steering angle sensor, 2d ...... Centering spring, 3 ... Controller, 4 ... Relay, 5 ... CPU, 6 ... Abnormality indicator lamp, 7 ... Vehicle speed sensor, 8 ... Front steering angle sensor, 9 ... Rear steering angle sensor, 10 …
… Column sensor, 11 …… Central set switch, 51 …… Convergence monitoring section, 52 …… Initial diagnosis and fail software section, 53…
… Relay driver, 54 …… Correlation checker, 55 …… EEPRO
M, 56 …… Adjustment unit.

Claims (1)

[Scope of utility model registration request] 1. A four-wheel steering system having a controller for electrically steering the rear wheels based on the steering wheel angle and the vehicle speed, so as to output a digital signal of a predetermined level when the front wheels are in a straight ahead position. The column sensor mounted on the vehicle, the front steering angle sensor that outputs a front steering angle signal that changes in an analog manner according to the steering angle of the front wheels, and the deviation between the target rear wheel position and the current rear wheel position within the specified time When the column sensor is outputting a digital signal of a predetermined level, the error processing means for stopping the power supply to the rear wheel steering motor when the value does not converge within the specified value According to the instruction from, it is checked whether the front steering angle signal is within a predetermined level range, and if it is not within the predetermined level range, the difference between the reference value and the actual front steering angle signal value is adjusted. Remember as value Adjusting value storage means, and a steering angle signal correction means for correcting an error included in the steering angle signal output from the steering angle sensor by the adjustment value stored in the adjustment value storage means. A means, the adjustment value storage means, and the front steering angle signal correction means are provided in the controller.