JPH0512143Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention operates in an anti-phase four-wheel steering mode in which the rear wheels are steered in the opposite phase to the front wheels, and an in-phase four-wheel steering mode in which the rear wheels are steered in the same phase as the front wheels. The present invention relates to a four-wheel steering vehicle that can selectively run in a two-wheel steering mode and a two-wheel steering mode in which the rear wheels are not steered.

[Prior Art] Such a four-wheel steering vehicle is known (for example, Japanese Patent Application Laid-Open No. 175469/1982), or the present applicant has disclosed a rear wheel steering lock device for driving in two-wheel steering mode in Utility Application No. 73447/1983. No. (see Utility Model Application Publication No. 62-184070), in such a four-wheel steering vehicle, the steering angle sensors of the front and rear wheels should detect the relative angle after the neutral sensor is turned on. For example, if the vehicle is parked in the same-phase four-wheel steering mode, so-called crab driving, and the key is turned off, the control device will not be able to determine the steering mode until the neutral sensor is turned on by operating the steering wheel when the key is turned on. Ta. Furthermore, in large vehicles, it is difficult to restore the vehicle to neutral by operating the steering wheel as described above.

Japanese Utility Model Application Publication No. 61-73476 discloses a technique that enables rear wheel steering when there is no failure in the rear steering control device and the rear wheel steering device is locked at the neutral position. Therefore, in this known technique, when the key is turned off during crabbing, the rear wheels cannot be steered unless the rear wheels are returned to the neutral position once, as described above.

[Problem to be Solved] Therefore, the purpose of the present invention is to provide a steering mode that can determine the steering mode based on the situation of the front and rear wheels at that time without returning the front and rear wheels to the neutral position when the key is turned on.
Our objective is to provide wheel-steering vehicles.

[Means for solving the problem] According to the present invention, in a four-wheel steering vehicle capable of selectively driving in an anti-phase four-wheel steering mode in which the rear wheels are steered in the anti-phase to the front wheels, an in-phase four-wheel steering mode in which the rear wheels are steered in the same phase to the front wheels, or a two-wheel steering mode in which the rear wheels are not steered, a control means is provided which determines the steering mode at key-on based on signals from an engine start detection means, a front wheel steering angle detection means, and a rear wheel steering angle detection means, and the control means calculates a target value of the rear wheel steering angle in the in-phase mode from the front wheel steering angle when the rear wheels are turned off after the key is turned on, and The system has a function of calculating the deviation from a target value, then determining whether the deviation of the rear wheels from neutral is greater than the deviation between the rear wheel steering angle and the target value, and if so, setting the in-phase mode, and if so, calculating the rear wheel steering angle target value in the opposite phase mode from the front wheel steering angle, then calculating the deviation between the rear wheel steering angle and the target value of the rear wheel steering angle, and determining whether the deviation of the rear wheels from neutral is greater than the deviation between the rear wheel steering angle and the target value of the rear wheel steering angle, and if so, keeping the in-phase mode, and if so, setting the opposite phase mode.

[Description of operation and effect] Therefore, when the key is turned on with the rear wheels turned off, the control means calculates the target value of the rear wheel steering angle in the same phase mode and in the opposite phase mode from the front wheel steering angle and the rear wheel steering angle. Since the calculated value is compared with the current deviation of the rear wheels from neutral, it is certain to determine whether to set the same phase mode or the opposite phase mode. In other words, when the key is on, the current absolute steering angle is detected, and based on the detected steering angle, the same steering mode as when the key is off is determined. can return to the position.

Therefore, unlike the prior art, there is no need for unnecessary suspension to return to the neutral position. Also,
Even if you forcefully steer the front wheels when the key is off, you can set the steering mode closest to that condition when the key is on.

Therefore, according to the present invention, the steering mode when the key is off can be determined when the key is on, and the vehicle can be driven extremely conveniently as a four-wheel steering vehicle.

[Examples] Examples of the present invention will be described below with reference to the drawings. In FIG. 1, a steering wheel 10
A steering gear box 11 is connected to the
A pitman arm 12 connected to the gearbox 11 is connected to a front wheel steering arm 14 via a drag link 13. Note that 15 is the kingpin and 16 is the tie rod.

On the other hand, a hydraulic cylinder 17 is provided between the rear wheel steering arm 18 and the rear axle housing 19. The hydraulic cylinder 17 is a double-acting type, and the cylinder chambers 17a and 17b are connected to hydraulic piping (hereinafter referred to as piping) via a switching valve 23.
It is connected to the reserve tank 28 via a pump unit 20 driven by an engine 30 by L1 or via a pipe L2. In addition, 2
1 is a flow control valve with relief, 22 is a relief valve, 24 is a cooler, 25 is a filter, 26 is an oil pressure sensor, and 27 is a stop valve.

The switching valve 23 is a 4-port, 3-position type, and is switched by a stepping motor 29.
When the parallel connection is in position I, the cylinder chamber 17a
The pressure oil of the pump unit 20 is guided to turn the rear wheel to the right, and when it is in the cross connection position, the cylinder chamber 1 is
Pressure oil is guided to 7b and turned to the left, so that both cylinder chambers 17a and 17b communicate with each other when in the neutral position.

A rear wheel steering lock device (hereinafter referred to as a lock device) 32 according to a known technique is provided between the rear axle housing 19 and the rear wheels, and the lock device 32 locks when not in operation and locks when in operation. a lock release cylinder 32a for releasing the lock;
4WS ready sensor 32b detects rear wheel unlocking, neutral lock sensor 32 detects locking
c is provided.

Further, the gearbox 11 is provided with a front steering angle sensor 33 that detects the absolute steering angle of the front wheels, a front neutral sensor 34 that detects the neutrality of the front wheels is provided near the pitman arm 12, and the rear axle housing 19 is provided with a front steering angle sensor 33 that detects the absolute steering angle of the front wheels. The angle sensor 35 and the hydraulic cylinder 17 are provided with a rear neutral sensor 36,
The transmission 60 includes a vehicle speed sensor 61 that detects vehicle speed, and the engine 30 includes an engine rotation sensor 31 that detects whether or not the engine is rotating.
is provided.

Furthermore, in the driver's cab, there is a mode changeover switch 37 for switching between front wheel steering (2WS), four-wheel steering (4WS) same-phase, and 4WS opposite-phase steering modes, a mode display lamp 38 for displaying the steering mode, and an emergency switch 39. is provided. These devices and sensors 26, 31, 32b, 32c, 33 to 37, 39 are connected to a control unit 40, respectively.

In FIG. 2, the control unit 40 includes a central processing unit (CPU) 41, a RAM 42, a ROM 53,
Watchdog timer (WDT) 43, oscillation circuit 4
4. A frequency dividing circuit 45 is provided. The central processing unit 41 includes an input circuit 50 and an input interface 46.
Sensors 26, 31, 32b, 3 input via
2c, 34, 36 and switches 37, 39, and the sensors 33, 3 input via the waveform type circuit 51 and pulse input interface 47.
5 and 61, and outputs a control signal to the mode display lamp 38 and the operating section of the lock release cylinder 32a via the output interface 48. A control signal is outputted to the stepping motor 29 of the hydraulic cylinder 23 via the hydraulic cylinder 23, and the front steering angle and rear steering angle are controlled as shown in FIG.

Further, the control unit 40 determines the steering mode according to the control flow shown in FIG. 4 when the key is turned on. That is, when the key is turned on, conditions are set in the central processing section 41 (step S1). Next, it is determined whether the engine is rotating based on the signal from the engine rotation sensor 31 (step S2), and if NO, the process moves to step S5, and if YES, it is determined whether the power-on mode flag is ON or not. (Step S3), and if NO, proceed to Step S.
Move on to 5. In step S5, the front wheel steering angle θf is detected based on the signal from the front steering angle sensor 33. Next, the rear wheel steering angle θr is detected based on the signal from the rear steering angle sensor 35 (step S6).
First, the 2WS mode is temporarily set (step S7).
Next, the deviation ΔθM of the rear wheels from neutral is calculated (step S8), and the deviation ΔθM is the plus θ shown in FIG.
2WS and -θ2WS are within the allowable range (step S9). If YES, proceed to step S19 while remaining in the 2WS mode. In the case of NO, that is, when the rear wheels are turned, the front wheel steering angle θf is changed to the rear wheel steering angle θr in the same phase mode.
A target value θA is calculated (step S10), and a deviation ΔθA between the rear wheel steering angle θr and the target value θA is calculated (step S11). Next, it is determined whether the deviation ΔθM of the rear wheels from neutral is larger than the deviation ΔθA obtained in the front step S11 (step S12). YES
If so, set the in-phase mode (step S1).
3) Correct the deviation amount ΔθM to ΔθA. If NO, the process moves to step S15. Step S15
In step S1, a rear wheel steering angle target value θB in the reverse phase mode is calculated from the front wheel steering angle θf, and then a deviation ΔθB between the rear wheel steering angle θr and the target value θB is calculated.
6). Next, it is determined whether the deviation ΔθM is larger than the deviation ΔθB (step S17), and if NO, the process moves to step S19 while maintaining the same phase mode.
If YES, the reverse phase mode is set (step S18) and the process moves to step S19. Step S
19, from step S5 to step S1
Based on the judgments up to 8, the pattern flag indicating that the mode closest to the normal mode pattern has been determined based on the relationship of the front wheel steering angle θr is turned ON, and the process proceeds to step S.
Return to 2. Therefore, since step S3 becomes YES, step S4 moves to another rear wheel steering angle control routine, which will not be described, according to the respective set modes. As described above, with the power-on mode flag turned ON in step S19,
When the key is turned on after stopping, the control mode is the same as when the key is off when the vehicle is stopped.For example, as shown in Fig. 6, if the vehicle is parallel parked from position A to position B in the same phase mode, it is necessary to turn on the key and back up. If it does, it can return to the original position A, and there is no need to perform unnecessary suspension. Furthermore, even if the front wheels are forcibly steered when the key is off, the control mode closest to the parking mode can be determined from the front and rear wheel steering angles.

[Effects of the invention] As described above, the present invention provides the following excellent effects.

(i) Even if the vehicle is stopped in a certain steering mode and the key is turned off, the steering mode at which the key was turned off can be determined the next time the key is turned on.

() Therefore, driving is convenient because there is no need to return the steering wheel to the neutral position when the key is turned on, unlike in the prior art.

() There is no need to make unnecessary deferrals.

() Even if you force the front wheels to steer a little when the key is off, you can set a steering mode that approximates that state.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention;
Figure 2 is a control block diagram, Figure 3 is a steering angle characteristic diagram,
FIG. 4 is a control flowchart, FIG. 5 is a steering mode determination map, and FIG. 6 is a plan view illustrating an example of the effect. 17...Hydraulic cylinder, 23...Switching valve,
31... Vehicle speed sensor, 33... Front steering angle sensor, 34... Front neutral sensor, 35... Rear steering angle sensor, 36... Rear neutral sensor, 37...
Mode changeover switch, 40...control unit.

Claims (1)

[Scope of utility model registration request] Opposite-phase 4-wheel steering mode, in which the rear wheels are steered in the opposite phase to the front wheels, and same-phase 4, in which the rear wheels are steered in the same phase as the front wheels.
A four-wheel steering vehicle capable of selectively running in a wheel steering mode and a two-wheel steering mode in which the rear wheels are not steered, comprising an engine start detection means, a front wheel steering angle detection means, and a rear wheel steering angle detection means. A control means is provided which determines the steering mode when the key is turned on based on the signal, and the control means calculates a target value of the rear wheel steering angle in the same phase mode from the front wheel steering angle when the rear wheels are turned off after the key is turned on. Then, the deviation between the rear wheel steering angle and the target value is calculated, and then it is determined whether the deviation of the rear wheels from neutral is larger than the deviation between the rear wheel steering angle and the target value, and if it is, the same phase is determined. mode, calculate a rear wheel steering angle target value in the reverse phase mode from the front wheel steering angle if it is small, then calculate the deviation between the rear wheel steering angle and the target value of the rear wheel steering angle, and then calculate the deviation between the rear wheel steering angle and the target value of the rear wheel steering angle. Determines whether the deviation of the wheels from neutral is greater than the deviation between the rear wheel steering angle and the target value of the rear wheel steering angle, and if it is smaller, the same phase mode is maintained, and if it is larger, the opposite phase mode is set. 4 characterized by having the function of
Wheel steering vehicle.