JPH03287470A - Four-wheel steering control device - Google Patents

Abstract

PURPOSE:To satisfactorily maintain the steering property at the time of reverse running by automatically switching the steering mode to the reverse-phase four-wheel steering mode for a turn with the minimum turning radius when a working machine is lifted, and automatically switching the steering mode to the rear wheel steering mode when a forward/reverse transfer lever is shifted to the reverse position. CONSTITUTION:A lift position detecting sensor 32 transmits a signal to a CPU when a hydraulic lever 31 is set on, and a controller detects that a ground working machine is in the lift position state. A shift position detecting sensor 34 transmits a signal to the CPU when a forward/reverse transfer lever 33 is shifted to the reverse position, and the controller detects that a vehicle is in the reverse running state. A steering mode transfer switch switches the steering mode to an optional mode among modes 1-4, and a signal indicating which mode is selected is transmitted to the CPU via an input interface. The reverse- phase four-wheel steering mode is selected when the working machine is in the lift position. The rear-wheel steering mode is preferentially selected when the forward/reverse transfer lever 33 is in the reverse running position.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a four-wheel steering control device, and in particular, a system for controlling a four-wheel steering control device, which controls steering modes when a working machine connected to a power vehicle ascends and descends, as well as when traveling backwards. This invention relates to a four-wheel steering control device that automatically switches.

[Conventional technology] In power vehicles such as passenger control machines and tractors,
Recently, there has been an increase in the number of vehicles in which both the front wheels and the rear wheels can be freely steered. In order to be able to steer only the front wheels, only the rear wheels, or both the front and rear wheels, some have a structure in which the steering mode is switched by a combination of gears, and others have a structure in which the front and rear drag arms are rotated by hydraulic cylinders. etc. are known.

For example, in agricultural work, when a power vehicle advances several units in front wheel steering mode and reaches the end of several units, the rear working equipment is raised and switched to reverse phase four-wheel steering mode. The front wheels and rear wheels are turned in opposite phases to 17, and the turning radius is made as small as possible to prevent damage to the ridges and crops. Furthermore, if there is no turning space when reaching the end of several units, the work may be continued while the power vehicle is moved backwards. At such times, in the front wheel steering mode, the wheels on the rear side in the direction of travel are steered, making running unstable, so the mode is switched to the rear wheel steering mode and the wheels on the front side in the direction of travel are steered.

[Problems to be Solved by the Invention] As mentioned above, conventionally, when turning after traveling forward in the front wheel steering mode, the work equipment is first raised and switched to the opposite phase four-wheel steering mode, and then the machine is turned again after turning. The work equipment is lowered and switched to front wheel steering mode. In addition, when performing agricultural work by moving several machines back and forth while repeatedly moving back and forth, the mode is switched to the rear wheel steering mode after traveling forward in the front wheel steering mode. Therefore, the steering mode is manually switched each time the vehicle turns or operates the forward/reverse switching lever, making the operation complicated. In addition, the operator may forget to switch the steering mode, and in such a case, the power vehicle may turn in an unexpected direction against the operator's will, which is dangerous.

Therefore, a technical problem has arisen that needs to be solved in order to easily switch the steering mode when turning and switching forward and backward, and to prevent operator errors.
The present invention aims to solve this problem.

[Means for Solving the Problems] This invention was proposed in order to achieve the above-mentioned object, and a steering cylinder is attached to each of the front and rear drag arms, so that both the front wheels and the rear wheels can be freely steered. In addition, in a power vehicle in which a working machine is connected to the rear of the vehicle and the working machine can be raised and lowered by a lift cylinder, a sensor for detecting the raising and lowering position is provided on the hydraulic lever that operates the lift cylinder, and the When the sensor detects that the work equipment is in the raised position, it switches to reverse phase four-wheel steering mode, and the forward/reverse switching lever is equipped with a sensor for detecting the shift position, and the sensor detects whether the forward/reverse switching lever moves backward. It is an object of the present invention to provide a four-wheel steering control device characterized in that a CPU is provided with a control section that switches to a rear-wheel steering mode with the highest priority when the vehicle is detected to be in a running position.

[Action] When the work machine is raised by the hydraulic cylinder, the sensor for detecting the lifting position detects the rise of the work machine and transmits it to the CPU, and the control unit determines that the power vehicle is in a turnable state. In such a case, a command is transmitted from the control unit to each steering cylinder to rotate the front wheels and rear wheels in opposite phases, and the power vehicle enters the opposite phase four-wheel steering mode.

In addition, when the powered vehicle travels forward in the front wheel steering mode, then stops and shifts the forward/reverse switching lever to the reverse running position, the shift position detection sensor detects the shift of the forward/reverse switching lever. The information is transmitted to the CPU, and the control unit determines that the powered vehicle is ready to travel backwards. In such a case, a command is transmitted from the control unit to each steering cylinder, the front wheels are fixed in a straight-ahead state, and only the rear wheel steering cylinder is operated, putting the power vehicle in rear wheel steering mode.

Even when the working machine is raised, when the forward/reverse switching lever is shifted to the reverse traveling position, the reverse steering mode takes priority and the power vehicle enters the rear wheel steering mode.

[Embodiment] An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. Figure 1 shows the side view of the passenger management machine (1), and
The figure shows the plane. Final cases (3) (3) are installed on the left and right sides of the front axle (2) of the passenger management machine (1).
is attached to transmit the driving force to the left and right front wheels (4) (4), and the knuckle arm (
5X5) is provided protrudingly to connect one end of the drag link (6) (6), and the other end of the drag link (6)<6) is connected to a drag link provided approximately in the center of the front axle (2). Connect to arm (7). This drag arm (7) is horizontally rotatable about the bin (8), and has a front end (9a) of a steering cylinder (9) connected to its negative side. Further, a potentiometer (10) is attached to the bottle (8) to serve as a means for detecting the steering angle of the front wheels (4) (4), and detects how many times the front wheels are turned in either the left or right direction.

On the other hand, the rear axle (■
(In the same way as the front wheels (4) (4), attach the final case (11 (119) to the left and right rear wheels of 1) (
14) Transmit the driving force to 04), and the final case 0
At the same time, connect one end of the drag link (+6) (IEI) to the rear axle (O of the Connected to the drag arm (■) provided approximately in the center.Furthermore, a steering cylinder (rear end (+9a) of Connect the potentiometer (to the rumored bottle)
4) is attached to serve as a means for detecting the steering angle of the rear wheels 04) (b).

In addition, a fully hydraulic controller (2) is provided at the rotation base of the steering wheel (21), and pressure oil from the hydraulic pump (2) is sent to the direction switching valve) and (4), and
Pressure oil is also fed to the main control valve (located at the rear of the chassis (11)). The passenger management machine (1
) A ground work machine (to) such as a rotary is attached to the rear of the main control valve (2) via a link mechanism. The working machine is designed to move up and down.

Then, a sensor @ for detecting the lifting position is provided on the hydraulic lever 01〉 that operates the lift cylinder ①, and the sensor ＠
2) detects whether the hydraulic lever 01) is on. In addition, a sensor 0 for detecting the shift position is installed on the forward/reverse switching lever (to) provided near the steering wheel I21).
) so as to be able to detect whether the forward/reverse switching lever (to) has been shifted to the reverse position.

Fig. 3 shows a hydraulic circuit, in which pressure oil is sent under pressure from an oil tank @ to a full hydraulic controller (to) by a hydraulic pump (2), and depending on the steering direction and rotation angle of the steering wheel (21), Pressure oil is fed under pressure from the track (R) or the track (I4) to the direction switching valves (to) and (2). The direction switching valves (2) and (4) move the spools to positions a, b, and c by turning on and off the solenoids (A), (B), and (C), and switch the direction of the pressure oil to the steering cylinder. (9) (Force it to IC!+.

The state shown in Figure 3 is each solenoid (8) (B) (C).
are all off, the spool is in position n, and the front wheel steering mode (mode 1) is in effect. For example, if the steering wheel (21) is steered to the right, pressure oil will flow from the track (ki) through the direction switching valve (4) and into the steering cylinder (
It is press-fitted into the cylinder from the track (9b) of 9), presses the piston (9c) backward, and returns to the direction switching valve (4) from the track (9d). Furthermore, pressure oil is sent under pressure to the direction switching valve @, but since the solenoid (^) (B) is off and in the spool or n position, pressure oil is not sent under pressure to the steering cylinder (spool), and the full hydraulic pressure is Controller @ track number (L)
Return to Therefore, said drag arm (7)
), the front wheels <4) (4) turn as shown by the chain lines, and the passenger management machine (1) turns to the right. In addition, the pressure oil branched from the flow divider (1) is sent under pressure to the main control valve Q force to operate the soft cylinder ■■.

Fig. 4 shows the state of the rear wheel steering mode (mode 2), in which the spool/id (B) of the direction switching valve (to) is turned on, the spool moves to position b, and the direction switching valve (
4) The thread/id (C) is turned on and the spool is moved to position C. For example, if the steering wheel (21) is steered to the right, pressure oil will be sent from the track (R) to the direction switching valve (4), but since the solenoid (C) is on and the spool is in position C. Steering cylinder (
Pressure oil is not sent under pressure to 9), and the spool of the direction switching valve is in position b, so the steering cylinder
Pressure oil is forced into the cylinder from 1'lb), presses the piston (19c) forward, and is discharged from the track (19d), passes through position b, and enters the full hydraulic controller (2) at track (19d).
Return to 14). Therefore, the drag arm (r't) rotates counterclockwise in the figure centering on the bin (east), and the rear wheel (14)
(14) is turned around as shown by the chain line, and the boarding control machine (1)
turns to the right.

Figure 5 shows the state of the same-phase four-wheel steering mode (mode 3), in which the solenoid (A) of the direction switching valve (to) is turned on, the spool moves to position a, and the direction switching valve is turned on. Both solenoids in (4) are off and the spool is n.
It is in the position of Therefore, if the steering wheel (21) is steered to the right, both the drag arm (7) and (O) rotate clockwise in the figure, and the front wheels (4) and (4) and the rear wheel H (n is indicated by a chain line). As shown, the boarding control machine (1) turns in the same phase and moves diagonally to the right.

Figure 6 shows the state of the reverse phase four-wheel steering mode (mode 4), in which the direction change valve solenoid (B) is turned on, the spool moves to position b, and the direction change valve (4) is turned on. Both solenoids are off and the spool is in position n. Therefore, when the steering wheel (21) is steered to the right, the drag arm (7) rotates clockwise in the figure and the drag arm (r/) rotates counterclockwise, causing the front wheels (4) (4) to rotate clockwise in the figure. ) and the rear wheels (X) (170) turn in opposite phases as shown by the chain lines, and the passenger management machine (1) turns to the right.

Here, FIG. 7 shows a block diagram of the present invention.

Potentiometers (10) and (1) are provided as steering angle detection means for the front wheels and rear wheels, and the potentiometers (
The steering angle signal detected in 10) and (1) is
After being A/D converted by the converter, it is transmitted to the CPU via the input interface. Sensor for detecting elevation position (
2) Sends a signal to the CPU when the hydraulic lever is on.
The control unit detects that the ground work equipment (to) has reached the raised position. In addition, the shift position detection sensor sends a signal to the CPU when the forward/reverse switching lever (2) is shifted to the reverse position, and the control unit detects that the vehicle is in the reverse running state. .

Then, the steering mode is switched to any one of modes 1 to 4 using the steering mode changeover switch, and a signal indicating which mode has been switched is transmitted to the CPU via the input interface.

In the CPU, the control unit judges each signal from the input interface and issues control commands to turn on and off the directional switching valve and each solenoid (A), (B), and (C) in (4) via the output interface. send. If you turn off the automatic-manual changeover switch and go into manual mode, you can change to any steering mode by operating the steering mode changeover switch, but if you turn on the automatic-manual changeover switch and go into automatic mode, the next The steering mode is automatically changed according to the procedure described in .

Figure 8 is a pulse timing chart in automatic mode, and when you turn on the 74 source switch and then switch the automatic-manual selector switch to automatic mode, the automatic mode indicator lamp lights up to indicate that you are in automatic mode. At the same time, the steering mode becomes mode 1 (PI). Here, when the hydraulic lever 01) is operated to operate the lift cylinder (to) (1) and raise the ground work equipment (to), the sensor for detecting the elevation position is turned on, and the control unit commands The buzzer is turned on for a certain period of time, and the steering mode is switched from mode 1 to mode 4 (P2). Hereinafter, it is assumed that the buzzer remains on for a certain period of time each time the steering mode is switched. Then, when the ground work machine (to) descends and the sensor (2) for detecting the elevation position is turned off, the steering mode is returned to mode 1 by a command from the control section (P3).

Next, when the forward/reverse switching lever @ is operated to shift to the reverse position, the shift position detection sensor 04) is turned on, and the steering mode is switched from mode 1 to mode 2 according to a command from the control unit (P4). . Then, mode 2 is maintained until the backward movement state is canceled (P5>), and even if the ground work equipment (to) rises during this time and the sensor (2) for detecting the elevation position is turned on, As for the steering mode, mode 2 takes priority without switching to mode 4. In this way, mode 2 takes priority in the reverse state, and for example, when the ground work equipment ascends and becomes mode 4, Even (P
6) At the same time as the steering wheel is shifted to the reverse/forward position, the steering mode is switched from mode 4 to mode 2 (PI).

Then, when shifted from the reverse position to another position, it returns to the original mode 4 (P8), and when the ground work equipment (to) descends, it returns to Mode 1 (P9), and the automatic-manual changeover switch is set to manual. Mode 1 (PIO) is maintained until the mode is switched to (PIO), and after that, it becomes any steering mode set by the steering mode changeover switch.

FIG. 9 is a flowchart. First, in step (2), the current steering mode set by the steering mode changeover switch is read, and 1 to 4 are stored as Mf values depending on the steering mode. In step ■, it is determined whether the automatic-manual changeover switch is on, and if it is on, step ■
Go to automatic mode. In step ■, the steering mode flag M○DEf is set to 1, and the steering mode is set to mode 1.
(front wheel steering mode). Then, when the sensor (2) for detecting the elevation position is turned on, the CPU determines that the ground work equipment (to) has risen, and sets the steering mode flag MODEf to 4 to enter the steering mode. Switch to mode 4 (opposite phase four-wheel steering mode) (step ■). If NO in step (2) or from step (2), the process proceeds to step (2), where it is determined whether or not the shift position detection sensor (b) is on. Here, if No, the process goes to step ■, and if Yes, step ■ sets the reverse flag Rf to 1, sets the steering mode flag MODEf to 2, switches to mode 2, and selects any steering mode. Control is performed so that mode 2 (rear wheel steering mode) takes priority even when the steering wheel is turned on. On the other hand, if the automatic-manual changeover switch is not on in step ■, step ■
Then, the flag Mf and reverse flag Rf of the steering mode changeover switch are read, and the actual steering mode flag MODEf is read in step [phase], and the process proceeds to step (2). In step ■, Mf and MODEf are compared to determine whether they match or not. If they match, the process returns to step ■; if they do not match, step ■
After setting the steering mode flag MODEf to be the same as Mf and switching the steering mode to correspond to Mf, the process returns to step (3).

Furthermore, by providing a switch that detects the operation of the clutch pedal or brake pedal at the position rXJ in Fig. 7, it is possible to determine whether the clutch pedal or brake pedal has been depressed, and when in manual mode, it is possible to determine whether the clutch pedal or brake pedal has been depressed. Control may be performed such that the steering mode is switched only when the steering mode is switched. In such a case, the steering mode is switched after the vehicle is almost stopped by operating the clutch or the brake, thereby improving the safety of the operation.

Note that this invention can be modified in various ways without departing from the spirit of the invention, and it goes without saying that this invention extends to such modifications.

[Effects of the Invention] As detailed in the above-mentioned embodiment, this invention automatically switches to the anti-phase four-wheel steering mode when the work equipment rises, and can turn with the minimum turning radius. If the work equipment is lowered after turning, the mode can be switched back to front wheel steering mode. In addition, when the vehicle is shifted to the forward/reverse switching Leno (-) or reverse position, it automatically switches to the rear wheel steering mode, maintaining good steering performance when driving backwards, and switches back to the front wheel steering mode when driving forward. Therefore, it is no longer necessary to manually switch the steering mode each time the work equipment is raised or lowered during a turn, or each time it repeats forward and backward movement, and work efficiency can be significantly improved. Since the rear wheel steering mode is switched to the rear wheel steering mode with the highest priority, the steering mode does not suddenly change even when the working machine is once raised in the reverse state, and this invention can also contribute to the safety of steering work.

[Brief explanation of drawings]

The figures show one embodiment of the present invention. Figure 1 is a side view of the passenger management machine, Figure 2 is an explanatory diagram showing the same plane, Figure 3 is a hydraulic circuit diagram in front wheel steering mode, and Figure 4 is a rear view. Hydraulic circuit diagram for wheel steering mode, Figure 5 is a hydraulic circuit diagram for same-phase four-wheel steering mode, Figure 6 is a hydraulic circuit diagram for anti-phase four-wheel steering mode, Figure 7 is a block diagram, and Figure 8 is a pulse diagram. The timing chart of FIG. 9 is a flowchart. (1)・・・Passenger management machine (4)・・・・・・
・Front wheel (7) (r71... drag arm (9) (
n... Steering cylinder (+[+) (a)...
Potentiometer (14)...on the rear wheel) (4)...Direction switching valve 00...
・Hydraulic lever (2)...Sensor for detecting elevation position (to)...
・・・Forward/forward switching lever

Claims (1)

[Claims] A power vehicle in which a steering cylinder is attached to each of the front and rear drag arms so that both front wheels and rear wheels can be freely steered, and a working machine is connected to the rear of the vehicle so that the working machine can be raised and lowered by a lift cylinder. In this case, a sensor for detecting the lifting position is installed on the hydraulic lever that operates the lift cylinder, and when the sensor detects that the work equipment is in the lifting position, it switches to the reverse phase four-wheel steering mode, and
A sensor is installed on the forward/reverse switching lever to detect the shift position.
A four-wheel steering control device characterized in that a CPU is provided with a control unit that switches to a rear wheel steering mode with the highest priority when the sensor detects that the forward/reverse switching lever is in the reverse traveling position.