JPH02179583A - Steering ratio controller for four-wheel steered vehicle - Google Patents

Abstract

PURPOSE:To improve safety with the simple constitution by allowing a clutch sensor to transmit a connection signal when the signal of a car speed sensor is below a prescribed value and a foot brake sensor is inoperative, and further maintaining the steering angle ratio detected by a steering angle ratio sensor is maintained when a speed change position sensor transmits a nonneutral signal. CONSTITUTION:An electronic controller 17 receives the signals of a car speed sensor 15, clutch sensor 39, foot brake switch 40, steering angle sensor 28, and a shift position sensor 28. When the car speed is below a prescribed value, and a clutch is connected, with the foot brake in nonoperative state, and the speed change position is outside a neutral position is judged, an actuator 8 is operated so that the steering angle ratio detected by a steering angle ratio sensor 28 is maintained. With this constitution, safety can be improved with the simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a steering angle ratio control device for a four-wheel steering vehicle.

[Prior Art] Steering angle ratio control in a four-wheel steering vehicle according to Japanese Patent Application No. 62-255205 IV, li! The vehicle has steering angle characteristics as shown in Fig. 3, and in particular, when the vehicle speed is O, the steering angle ratio (the ratio of the rear wheel steering angle to the front wheel steering angle) is set to a large value of 0 in the opposite phase. . In this control device, in case the power source battery is switched off, the electronic a control device is equipped with a backup RAM to drive the actuator at the steering angle ratio before the power was turned off. A backup power supply circuit is required, the configuration becomes complicated, and the lifespan of the backup battery becomes a problem.

In addition, in the above-mentioned control device, if the vehicle speed sensor fails while driving at high speed, the vehicle speed is determined to be 0 and the rear wheels are steered so that the steering angle ratio is set to kO, which impairs driving stability and is dangerous. . As disclosed in Japanese Unexamined Patent Publication No. 62-1467754, the method of providing a large number of vehicle speed sensors and determining the presence or absence of a failure by majority vote requires complicated control and increases costs. Furthermore, means for determining failure of the vehicle speed sensor based on a sudden change in vehicle speed does not work effectively except at the moment of failure.

[Problems to be Solved by the Invention] In view of the above-mentioned problems, an object of the present invention is to use a simple configuration to determine the failure of the vehicle speed sensor, and to detect the failure of the vehicle speed sensor when the vehicle speed sensor fails.
An object of the present invention is to provide a steering angle ratio control device that maintains the steering angle ratio detected by a steering angle ratio sensor immediately before failure.

[Means for solving the problem] In order to achieve the above object, the configuration of the present invention is such that the steering angle ratio control means for setting the rear wheel steering angle based on the signal of the vehicle speed sensor is configured such that:
When the signal value of the vehicle speed sensor is below a predetermined value, the constant brake sensor issues a non-operation signal, the clutch sensor issues a connection signal,
Further, when the shift position sensor issues a non-neutral signal, the steering angle ratio detected by the steering angle ratio sensor at that time is maintained.

[Operation] When the vehicle speed detected by the vehicle speed sensor is less than or equal to a predetermined value V, the foot brake switch is OFF, the clutch disengagement switch is OFF, and the gear shift switch that operates with the gear shift lever in the neutral position is OFF, the vehicle speed sensor The steering angle ratio is maintained based on the vehicle speed before the detected vehicle speed becomes equal to or less than the predetermined value vt. The actuator is operated to achieve this steering angle ratio.

[Example of R Ming] FIG. 2 is a plan view showing a schematic configuration of a four-wheel steering vehicle.

When the steering shaft 18 is rotated, for example, to the right by the handle 18a, the link mechanism 21 is driven by the output shaft of the front wheel steering mechanism 5, and the left and right knuckle arms 3, which are interlocked and connected by the tie rods 4, are rotated clockwise to rotate the front wheels. 2 is deflected to the right. At the same time, the control lever 26 is rotated clockwise about the support shaft 27 by the input rod 6 extending rearward from the link mechanism 21, and the control lever 26 is rotated clockwise about the support shaft 27 via the link 25 which is engaged with the arcuate groove of the l11111 lever 26 by the pin 24. hand,
The output rod 22 is pushed rearward, the tie rod 10 is pushed leftward by the rear wheel steering mechanism 9, and the left and right knuckle arms 12 supporting the rear wheels 13 are rotated counterclockwise.
The rear wheel 13 is deflected to the left (in the opposite phase to the front wheel).

The steering angle ratio is controlled by changing the engagement position between the pin 24 of the link 25 and the arcuate groove of the control lever 26.

For this reason, an actuator (step motor in the illustrated embodiment) is attached to the partial gear 23 formed integrally with the link 25.
8 gears are meshed. For example, pin 2 of link 25
4 to the left side of the support shaft 27, the handle 18a
In response to the cloth cutting, the rear wheel 13 is also deflected to the right (in the same phase as the 1rI wheel).

An electronic control unit 17 consisting of a microcomputer determines a steering angle ratio stored in a memory based on a signal from a vehicle speed sensor 15, and drives an actuator 8 based on an output signal from the electronic control unit 17. The memory of the microcomputer stores the steering angle ratio corresponding to the vehicle speed as shown in Figure 3 (however, if the vehicle speed is 0)
In this case, the steering angle ratio (0) is stored and set as a control map.

FIG. 1 is a block diagram showing a schematic configuration of the electronic III device 17. As shown in FIG. In Figure 1, 30 is the power battery;
31 is a key switch, and when the key switch 31 is closed, a transistor 32.3 drives the actuator 8.
3.34.35 and transistor 3 driving the safety relay
The electronic control device 17 including 6 is driven. Reference numeral 29 denotes a relay coil constituting a safety relay, and when this relay coil 29 is excited, a switch 29a opens. 37 is a warning light.

The electronic control system [17 includes a front wheel steering angle sensor 16, a steering angle ratio sensor 28, a shift position sensor 38 that detects whether the shift lever is in the neutral position, a vehicle speed sensor 15 that detects the vehicle speed,
A signal from a clutch sensor 39 is added to detect whether the clutch is disengaged. In order to send a signal indicating whether or not the engine is rotating, the voltage at the C terminal of the starter 44 (0 when the engine is stopped) is
volts (generated voltage during rotation) is applied to the electronic control unit 17 as an ON-OFF signal.

In order to obtain a signal as to whether or not the foot brake is in operation, when the relay coil 41 is energized by the foot brake switch 40, which is closed when the brake pedal is depressed, the switch 41a is closed and the brake light 42 is turned on, and at the same time, brake light 4
2 terminal voltage is applied as a signal to the electronic control unit 17.

To obtain a signal as to whether or not the parking brake is in operation, when the parking brake lever is pulled, the parking brake switch 46 closes and the parking brake light 45 lights up, and at the same time, the terminal voltage of the parking brake light 45 is output as an electronic signal. IIll device 1
Added to 7. The signal of the parking place switch 46 is
By directly connecting the relay coil 29 of the safety relay for cutting off power to the actuator 8, the actuator 8 is not driven when the parking brake switch 46 is ON, and the steering angle ratio before the parking brake is activated is Memory is maintained. Furthermore, even if the vehicle travels with the parking brake switch 46 in the ON state, the reduction gear of the actuator 8 serves as a lock, and the steering angle ratio before the parking brake is activated is memorized and maintained.

The front wheel steering angle sensor 16 uses, for example, the rotational displacement of the output shaft or the steering shaft 18 of the front wheel steering mechanism 5 as a change in resistance value.
The steering angle ratio sensor 28 is configured to detect the rotational displacement of the partial gear 23 shown in FIG. 2 as a change in resistance value. The clutch sensor 39 is configured as a switch that closes when the clutch pedal is depressed. The shift position sensor 38 is configured as a switch that closes when the shift lever is placed in the neutral position.

Next, the operation of the steering angle ratio control device for a four-wheel steering vehicle according to the present invention will be explained. The steering angle ratio control device according to the present invention turns off the safety relay and prevents the actuator 8 from operating when the engine is stopped or the parking brake is operating.

During normal driving, the steering angle ratio is determined in accordance with the vehicle speed.

The steering angle ratio characteristics are set as shown in Figure 3 (however, when the vehicle speed is 0)
Then, let the steering angle ratio O) and the control map be r? The settings are stored in the memory of the microcomputer.

When the detected signal value of the vehicle speed sensor 15 is 0, whether this means a failure of the vehicle speed sensor 15 or a true stop is determined as follows, and the steering angle ratio is determined. Vehicle speed sensor 1
The signal value of 5 is O, and the foot brake switch 40 is 0.
When the FF1 clutch disengagement switch 39 is OFF and the shift position sensor 38 is OFF (the shift lever is not in the neutral position), it is determined that the vehicle speed sensor 15 is malfunctioning, and the steering angle ratio sensor 2 is
The steering angle ratio detected by 8 and stored in the register is read out, this is set as a sharp steering angle ratio, and the actuator 8 is driven so as to exceed this steering angle ratio.

When the signal value of the vehicle speed sensor 15 is 0, the foot brake switch 4o is ON, the clutch disengagement switch 39 is ON1, or the shift position sensor 38 is ON, it is determined that the vehicle is truly stopped, and the steering angle ratio is set to O. .

FIG. 4 is a flowchart of a control program when the above-mentioned IIJill is executed by an electronic control device 1117 consisting of a microcomputer. In the figure, pH ~ p2
9 indicates each step of the flowchart. The control program of the present invention is repeatedly calculated at predetermined time intervals. The control program is started at the same time as the power is turned on at pll, and the steering angle ratio ks is read by the steering angle ratio sensor 28 at p12. p13
The value of the register kaak:ks is stored in p14, and the switch 29a of the safety relay is turned off to turn on the transistor 36 to cut off the power supply to the actuator 8, thereby preventing malfunction of the actuator 8 peculiar to the start-up. p1
In step 5, it is determined whether 1 second (less than 1 second) has elapsed, and when 1 second has elapsed, the process advances to p16. During this time, an interrupt program is used to read vehicle speed data, etc.

plB determines whether the engine is rotating or not.

If the engine is not rotating, turn on the transistor 36 that drives the safety relay in p17 and proceed to p29.

When the engine is rotating at plB, it is determined from the signal from the parking brake switch 46 at l) 1g whether or not the parking brake is operating. If the parking brake is operating, the process advances to p29 via p17; if the parking brake is not operating in p18, the transistor 36 that drives the safety relay is turned off in p19.

At p20, find the steering angle ratio k from the vehicle speed ■. This steering angle ratio is stored and set in the memory of the microcomputer as a control map with characteristics as shown in FIG. 3 (however, when the vehicle speed is O, the steering angle ratio is O).

In p21, the vehicle speed V is set to a predetermined value vt (for example, 0.5 km/h
). Vehicle speed V is a predetermined value vt
If it is larger than , proceed to p2B. isi speed v on p21
If is smaller than the predetermined value vt, it is determined in p22 whether or not the foot brake is operating. If the constant brake is in operation, set the steering angle ratio to kaa@ in p25 and proceed to p2B.

If the foot brake is not activated, it is determined in p23 whether the clutch is disengaged (the clutch pedal is depressed). If the clutch is disengaged, the process advances to p25; if the clutch is connected, it is determined in p24 whether the gear shift lever is in the neutral position. If the shift lever is in the neutral position, the process advances to p25, and if the shift lever is in the non-neutral position, the steering angle ratio is set to ksa@ in p26. p2
1 and the target steering angle ratio is k. The actuator 8 is operated to achieve the target steering angle ratio at p28, and the process ends at p29.

〔Effect of the invention〕

As described above, the present invention provides a steering angle ratio control means that sets a rear wheel steering angle based on a signal from a vehicle speed sensor, and when the signal value of the vehicle speed sensor is equal to or less than a predetermined value, the foot brake sensor issues an inactivation signal;
When the clutch sensor issues a connection signal and the shift position sensor issues a non-neutral signal, the steering angle ratio detected by the steering angle ratio sensor at that time is maintained, so the following effects are achieved.

(a) If the vehicle speed sensor fails, the signal from the vehicle speed sensor becomes 0 (lue/h) even though the vehicle is actually traveling at high speed, and the rear wheels are steered to a steering angle ratio kO with a large opposite phase corresponding to a vehicle speed of 0. , the conventional drawback of dangerous driving conditions is eliminated.

(b) Simply setting the steering angle ratio to 0 when the vehicle speed is 0 is not enough to change the steering angle ratio from 1 to k each time the vehicle temporarily stops.
The rear wheels are steered so that the position is o, causing the rear tires to wear out.

If the operating state of the parking brake, constant brake, clutch pedal, and gear shift lever determines that the vehicle speed sensor is not malfunctioning and that the vehicle is truly stopped, the steering angle ratio will be maintained at the value immediately before the stop, which will solve the problem described above. is resolved.

(C) A safety relay installed in the actuator that controls the steering angle ratio prevents the actuator from operating when the engine is stopped or the parking brake is applied, which prevents excessive load from being applied to the steering linkage and prevents the actuator from driving. Fatigue of transistors used is reduced.

(d) When the engine is driven while the vehicle is stopped, the clutch pedal is not depressed, the parking brake is deactivated, and the momentary brake is released, the steering angle ratio becomes 0 and the vehicle is in a two-wheel steering state. After that, if you lightly apply the parking brake (to the extent that the parking brake light lights up) and then start driving, you will be able to drive with two-wheel steering, and avoid collisions with side walls due to the overhang of the rear of the vehicle when starting with four-wheel steering. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an electronic 11JIO device for controlling the steering angle ratio of a four-wheel steering vehicle according to the present invention, FIG. 2 is a plan view showing a schematic configuration of the steering angle ratio control mechanism, and FIG. The characteristic diagram, FIG. 4, is a flowchart illustrating the software that controls the steering angle ratio. 8: 7 actuator 15: Vehicle speed sensor 17: Electronic control unit 28: Steering angle ratio sensor 38: Shift position sensor
39: Clutch sensor 40: Foot brake switch 4
6: Parking brake switch patent applicant Isuzu Motors Co., Ltd.

Claims (1)

[Claims] The steering angle ratio control means sets the rear wheel steering angle based on the signal from the vehicle speed sensor, and when the signal value of the vehicle speed sensor is below a predetermined value, the foot brake sensor issues a non-operation signal, the clutch sensor issues a connection signal, and the gear shift A steering angle ratio control device for a four-wheel steering vehicle, characterized in that when a position sensor issues a non-neutral signal, the steering angle ratio detected by the steering angle ratio sensor at that time is maintained.