JP2822576B2 - Four-wheel steering control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-wheel steering control device, and more particularly to a four-wheel steering control device, which automatically switches to a steering mode when a working machine connected to a powered vehicle is moved up and down and when the vehicle is traveling backward. The present invention relates to a four-wheel steering control device that switches to a four-wheel steering control.

[Prior Art] In recent years, power vehicles including a passenger management machine, a tractor and the like have recently increased both front wheels and rear wheels so as to be steerable. In order to make it possible to steer only the front wheels, only the rear wheels, or the front and rear wheels, there is a configuration in which the steering mode is switched by a combination of gears, and a configuration in which the front and rear drag arms are rotated by hydraulic cylinders. Things are known.

For example, in agricultural work, when the powered vehicle advances in the ridge field in the front wheel steering mode and reaches the end of the ridge field, the work machine at the rear is raised and switched to the anti-phase four-wheel steering mode. Then, the front wheel and the rear wheel are turned in opposite phases, and the turning radius is made as small as possible to prevent damage to the ridges and crops.
If there is no space for turning when reaching the end of the ridge, the work may be continued while the power vehicle is moved backward. At that time, in the front wheel steering mode, the rear wheels in the traveling direction are steered, so that the traveling becomes unstable. Therefore, the mode is switched to the rear wheel steering mode and the front wheels in the traveling direction are steered.

[Problems to be Solved by the Invention] As described above, conventionally, when turning after traveling forward in the front wheel steering mode, the work implement is once raised and switched to the anti-phase four-wheel steering mode, and after turning, the work is performed again. The aircraft is descending and switched to the front wheel steering mode. In addition, when farm work is performed by reciprocating the ridge while repeating the front and rear wheels, the vehicle is switched to the rear wheel steering mode after traveling forward in the front wheel steering mode. Therefore, the steering mode is manually switched every time the vehicle turns or when the forward / backward switching lever is operated, so that the operation is complicated. Then, the operator sometimes forgets to switch the steering mode, and in that case, the powered vehicle turns in an unexpected direction against the intention of the operator, which is dangerous.

Therefore, it is possible to easily perform the steering mode switching at the time of turning and forward / backward switching, and a technical problem to be solved in order to prevent an erroneous operation of an operator arises. The present invention solves this problem. The purpose is to do.

[Means for Solving the Problems] The present invention has been proposed to achieve the above 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 are formed so as to be steerable. In addition, in a powered vehicle in which a working machine is connected to a rear portion of the vehicle and the working machine is formed to be able to move up and down by a lift cylinder,
A hydraulic lever for operating the lift cylinder is provided with a sensor for detecting the vertical position. When the sensor detects that the work implement is in the vertical position, it switches to the reverse-phase four-wheel steering mode and shifts to the forward / reverse switching lever. A sensor for position detection is provided, and a control unit that switches to the rear wheel steering mode with the highest priority when the forward / reverse switching lever detects the reverse traveling position is provided in the CPU. It is intended to provide a four-wheel steering control device.

[Operation] When the work implement is raised by the hydraulic cylinder, the sensor for detecting the elevation position detects the rise of the work implement and transmits it to the CPU, and the control unit determines that the powered vehicle is in a turnable state. . In such a case, a command is transmitted from the control unit to each of the steering cylinders, and the front wheels and the rear wheels are turned in opposite phases, so that the powered vehicle is in an opposite-phase four-wheel steering mode.

Also, when the powered vehicle stops in the front wheel steering mode after traveling forward and temporarily shifts the forward / reverse switching lever to the reverse traveling position, a shift position detection sensor detects the shift of the forward / backward switching lever and the CPU detects the shift. And the control unit determines that the powered vehicle is in a state in which the vehicle can travel backward. In such a case, a command is transmitted from the control unit to each of the steering cylinders, the front wheels are fixed in a straight running state, only the rear-wheel steering cylinders are operated, and the power vehicle enters the rear-wheel steering mode.

Then, even when the work implement rises, when the front wheel advance switching lever is shifted to the reverse travel position, the reverse steering mode takes precedence, and the powered vehicle enters the rear wheel steering mode.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a side view of a passenger management machine (1), and FIG.
The figure shows the plane. On the left and right sides of the front axle (2) of the passenger management machine (1), final cases (3) and (3)
, The driving force is transmitted to the left and right front wheels (4), (4), and the knuckle arms (5), (5) are protruded from the final cases (3), (3), and one end of the drag link (6) (6) Connect the parts and drag link (6) (6)
Is connected to a drag arm (7) provided substantially at the center of the front axle (2). This drag arm (7)
Is rotatable in a horizontal direction about a pin (8), and is connected to a front end (9a) of a steering cylinder (9) on one side thereof. Further, a potentiometer (10) is attached to the pin (8) to serve as means for detecting the steering angle of the front wheels (4), (4), and detects how many times the front wheel is turned to the left or right.

On the other hand, the rear axle (1
2) In the same way as the front wheels (4) and (4),
By attaching the final cases (13) and (13), the driving force is transmitted to the left and right rear wheels (14) and (14), and the knuckle arms (15) and (15) are protruded from the final cases (13) and (13). Connect one end of the drag link (16) (16) and connect the other end of the drag link (16) (16) to the rear axle (1).
Connect to the drag arm (17) provided at the approximate center of 2). Further, a rear end (19a) of a steering cylinder (19) is connected to one side of a drag arm (17) rotatable about a pin (18), and a potentiometer ( 20) is attached as a means for detecting the steering angle of the rear wheels (14) (14).

Further, a full hydraulic controller (23) is provided at a turning base of the steering (21), and pressure oil from a hydraulic pump (24) is pressure-fed to the direction switching valves (25) and (26). (11) Pressure oil is also fed to the main control valve (27) provided at the rear. A ground work machine (29) such as a rotary is attached to a rear portion of the riding management machine (1) via a link mechanism (28), and a lift cylinder is operated by pressure oil from the main control valve (27). (30) (30) is operated so that the ground work machine (29) is raised and lowered.

Then, a sensor (32) for detecting the elevation position is provided on the hydraulic lever (30) for operating the lift cylinder (30),
The sensor (32) detects whether the hydraulic lever (31) is on. Further, a forward / backward switching lever (33) provided near the steering (21) is provided with a shift position detecting sensor (34) to determine whether the forward / backward switching lever (33) has been shifted to the reverse position. Formed to be detectable.

FIG. 3 shows a hydraulic circuit, and an oil tank (35).
Hydraulic pump (24) from the hydraulic controller (2
Pressure oil is sent to 3), and depending on the steering direction and the turning angle of the steering (21), the pressure oil flows from the oil port (R) or the oil port (L) to the direction switching valves (23) and (23). 24). Each directional control valve (25) (2
In 6), when the solenoids (A), (B), and (C) are turned on and off, the spool moves to positions a, b, and c, and switches the direction of the pressure oil to the steering cylinders (9) and (19). Pump. Third
In the state shown in the figure, the solenoids (A), (B), and (C) are all turned off, the spool is at the position n, and the wheel is in the front wheel steering mode (mode 1). For example, if the steering (21) is steered to the right, the pressure oil is forced into the cylinder from the oil port (9b) of the steering cylinder (9) through the direction switching valve (26) from the oil port (R), The piston (9c) is pressed backward to return to the direction switching valve (26) from the oil port (9d). Further, the pressure oil is fed to the direction switching valve (25), but the pressure oil is not sent to the steering cylinder (19) because the solenoids (A) and (B) are off and the spool is at the position n. Then, the process returns to the oil port (L) of the all hydraulic controller (23). Therefore, the drag arm (7) is connected to the pin (8).
, The front wheels (4) and (4) turn as indicated by the chain line, and the passenger management machine (1) turns right. Alternatively, the pressure oil branched from the flow divider (36) is pressure-fed to the main control valve (27) to operate the lift cylinders (30) (30).

FIG. 4 shows a state of the rear wheel steering mode (mode 2).
When the solenoid (B) of the direction switching valve (25) is turned on, the spool moves to the position b, and when the solenoid (C) of the direction switching valve (26) is turned on, the spool moves to the position c.
Has moved to the position. For example, when the steering (21) is steered to the right, pressure oil is fed from the oil port (R) to the direction switching valve (26), but the solenoid (C) is on and the spool is at the position c. Therefore, the pressure oil is not fed to the steering cylinder (9) by pressure, and since the spool of the direction switching valve (25) is at the position b, the pressure oil is pressed into the cylinder from the oil port (19b) of the steering cylinder (19). Then, the piston (19c) is pushed forward and discharged from the oil port (19d),
Oil port (L) of all hydraulic controllers (23) via position b
Return to Accordingly, the drag arm (17) rotates counterclockwise in the figure around the pin (18), the rear wheels (14) and (14) turn as indicated by the chain line, and the passenger management machine (1) moves to the right. Turn to

FIG. 5 shows a state of the in-phase four-wheel steering mode (mode 3). When the solenoid (A) of the direction switching valve (25) is turned on, the spool moves to the position a, and the direction switching valve ( 26) Both solenoids are off and spool is n
In the position. Therefore, when the steering (21) is steered to the right, both the drag arms (7) and (17) rotate clockwise in the drawing, and the front wheels (4) (4) and the rear wheels (14) (14) Turns in the same phase as indicated by the chain line, and the passenger management machine (1) skews rightward.

FIG. 6 shows the state of the anti-phase four-wheel steering mode (mode 4). When the solenoid (B) of the direction switching valve (25) is turned on, the spool moves to the position b and the direction switching valve ( 26) Both solenoids are off and spool is n
In the position. Therefore, when the steering (21) is steered to the right, the drag arm (7) rotates clockwise in the drawing, and the drag arm (17) rotates counterclockwise, so that the front wheels (4) and (4) and the rear wheel (4). The wheels (14) and (14) turn in opposite phases as indicated by the chain lines, and the passenger management machine (1) turns right.

FIG. 7 is a block diagram of the present invention. Potentiometer (10) as means for detecting steering angles of front and rear wheels
And (20) are provided, and the signal of the steering angle detected by the potentiometers (10) and (20) is A / D-converted by the A / D converter and then sent to the CPU via the input interface. Is transmitted. The elevation position detection sensor (32) transmits a signal to the CPU when the hydraulic lever (31) is on, and the control unit detects that the ground work machine (29) has entered the elevation position state. The shift position detection sensor (34) outputs a signal when the forward / reverse switching lever (33) is shifted to the reverse position.
A signal is transmitted to the CPU, and the control unit detects that the vehicle is in a reverse running state.

Then, the mode is switched to any one of the modes 1 to 4 by the steering mode switching 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 determines each signal from the input interface, and turns on / off the solenoids (A), (B), and (C) of the direction switching valves (25) and (26) via the output interface. Send a control command to. If the automatic-manual switching switch is turned off and the manual mode is set, the steering mode switching switch can be operated to change to any steering mode.However, if the automatic-manual switching switch is turned on and the automatic mode is set, the next mode is set. The steering mode is automatically changed according to the procedure described in (1).

FIG. 8 is a pulse timing chart in the automatic mode. When the automatic-manual switch is switched to the automatic mode after the power switch is turned on, the automatic mode display lamp is turned on and the automatic mode is set. At the same time, the steering mode is set to mode 1 (P1). Here, the hydraulic cylinder (30) is operated by operating the hydraulic lever (31).
When the ground work machine (29) is raised by activating the (30), the sensor (32) for detecting the vertical position is turned on, and the buzzer is turned on for a certain period of time by a command from the control unit, and the steering mode is set to mode 1 To mode 4 (P2). Hereinafter, it is assumed that the buzzer is turned on for a certain time each time the steering mode is switched. Then, when the ground work machine (29) descends and the elevation position detection sensor (32) is turned off, the steering mode is returned to mode 1 by a command from the control unit (P3).

Next, when the forward / reverse switching lever (33) is operated to shift to the reverse position, the shift position detecting sensor (34) is turned on, and the steering mode is changed to mode 1 by a command from the control unit.
To mode 2 (P4). Then, the mode 2 is maintained until the reverse state is released (P5), during which the ground work machine (29) is raised and the sensor (32) for detecting the elevation position is lifted.
The steering mode is set to mode 4 even when is turned on.
, The state of mode 2 has priority. As described above, in the reverse state, the mode 2 takes precedence. For example, even when the ground work machine (29) moves up to the mode 4 (P6), the vehicle is shifted to the reverse position on the way and the steering mode is simultaneously performed. Is switched from mode 4 to mode 2 (P7). When the vehicle is shifted from the reverse position to another position, the mode returns to the original mode 4 again (P8). When the ground work machine (29) descends, the mode returns to the mode 1 (P9). The mode 1 is maintained until the mode is switched to the manual mode (P10), and thereafter, the mode becomes an arbitrary steering mode set by the steering mode switching switch.

FIG. 9 is a flow chart. First, the current steering mode set by the steering mode switching switch is read in a step, and 1 to 4 are stored as Mf values according to the steering mode. In the step, it is determined whether or not the automatic-manual switching switch is on. When the switch is on, the process proceeds to the step and the automatic mode is set. In the step, the steering mode flag MODEf is set to 1, and the steering mode is set to mode 1 (front wheel steering mode). When the sensor for detecting the elevation position (32) is turned on (step), the CPU determines that the ground work machine (29) has risen, sets the steering mode flag MODEf to 4, and sets the steering mode. The mode is switched to mode 4 (anti-phase four-wheel steering mode) (step). When the answer is No in the step or from the step, the process proceeds to the step, and it is determined whether or not the shift position detecting sensor (34) is on. Here, if No, it will go to the step,
If yes, the reverse flag Rf is set to 1 at step and the steering mode flag MODEf is set to 2 to switch to mode 2, and mode 2 (rear wheel steering mode) has priority in any steering mode. Is controlled as follows. On the other hand, when the automatic-manual switching switch is not turned on in step, the process proceeds to step, in which the steering mode switching switch flag Mf and the reverse flag Rf are read, and the actual steering mode flag MODEf is read in step to proceed to step. In the step, Mf and MODEf
To determine whether or not the two are the same.If they are the same, return to the step.If they are not the same, set the steering mode flag MODEf to the same as Mf at the step,
After switching the steering mode so as to correspond to Mf, the process returns to the step.

A switch for detecting the operation of the clutch pedal or the brake pedal is provided at the position "X" in FIG. 7 so that it can be determined that the clutch pedal or the brake pedal is depressed. Control may be performed so that the steering mode is switched only when the operation is performed. In such a case, the steering mode is switched after the vehicle is almost stopped by performing the clutch operation or the brake operation, and the safety of the operation is improved.

The present invention can be variously modified without departing from the spirit of the present invention, and it goes without saying that the present invention extends to the modified one.

[Effect of the Invention] As described in detail in the above embodiment, the present invention automatically switches to the anti-phase four-wheel steering mode when the work machine rises, and can turn with the minimum turning radius. If the work machine is lowered after turning, the mode is switched again to the front wheel steering mode.
Further, when the forward / reverse switching lever is shifted to the reverse position, the mode is automatically switched to the rear wheel steering mode, the steering performance during reverse traveling is maintained well, and when traveling forward, the mode is switched again to the front wheel steering mode. Therefore, there is no need to manually switch the steering mode each time the work machine is raised or lowered or the vehicle is repeatedly moved forward and backward when turning, and the workability can be significantly improved. In any state, the rear-wheel steering mode is switched to the highest priority in the reverse state, so that the steering mode does not suddenly change even when the work implement is once raised in the reverse state, and the safety of the steering operation is improved. It is an invention that can also contribute to the nature.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a side view of a passenger management machine, FIG. 2 is an explanatory view showing the same plane, FIG. 3 is a hydraulic circuit diagram in a front wheel steering mode, and FIG. FIG. 5 is a hydraulic circuit diagram of the same-phase four-wheel steering mode, FIG. 6 is a hydraulic circuit diagram of the opposite-phase four-wheel steering mode, FIG. 7 is a block diagram, and FIG. FIG. 9 is a flow chart. (1) Riding machine (4) Front wheel (7) (17) Drag arm (9) (19) Cylinder for steering (10) (20) Potentiometer (14) … Rear wheel (25) (26)… Direction switching valve (31)… Hydraulic lever (32)… Sensor for detecting the vertical position (33)… Forward / reverse switching lever (34)… Shift position detection Sensors (A) (B) (C) …… Solenoid

Continuation of front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B62D 6/00 B62D 7/14

Claims (1)

(57) [Claims] 1. A steering cylinder is mounted on each of the front and rear drag arms to form a rear portion of a front wheel and a rear wheel so as to be steerable, and a working machine is connected to a rear portion of the vehicle so that the working machine can be raised and lowered by a lift cylinder. In the formed powered vehicle, a sensor for detecting the elevation position is provided on the hydraulic lever that operates the lift cylinder, and when the sensor detects that the work implement is at the elevation position, the mode is switched to the opposite-phase four-wheel steering mode. Also, a shift position detection sensor is provided on the forward / reverse switching lever, and when the forward / reverse switching lever detects that the vehicle is in the reverse traveling position, the control unit that switches to the rear wheel steering mode with the highest priority is executed by the CPU. A four-wheel steering control device provided in a vehicle.