JP3038771B2 - Four-wheel steering control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-wheel steering control device, and more particularly to switching to a steering mode at the end of work and to a steering mode set at power-on irrespective of turning positions of front and rear wheels. The present invention relates to a four-wheel steering control device that performs [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. These include 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 so that only the front wheels, only the rear wheels, or the front and rear wheels can be steered. It has been known. [Problems to be Solved by the Invention] The switching of the steering mode of the four-wheel steering device described above is performed by fixing the turning direction of the unsteered side wheel of the front wheel and the rear wheel. If the steering wheel is fixed in the facing state, the next steering operation is hindered. Therefore, the steering mode is switched after the front wheels and the rear wheels are once returned to the straight traveling state. However, if the steering is operated in the power-off state or the steering mode is switched to another steering mode after the end of the work, the turning position of the front and rear wheels will be The mode switching cannot be performed unless the front wheels and the rear wheels are in the straight running state, because they are different or do not match the turning positions of the front and rear wheels and the steering mode set after the work is completed. For example, if the rear wheels are not in the straight running state when the work is completed in the rear wheel steering mode, if the power is turned on in the state of switching to the front wheel steering mode at the time of power off, the mode switching is performed because the rear wheels are not steered while turning. Impossible. It is possible to store the final steering mode using a battery backup or a non-volatile memory, but this is costly and has no effect when the controller is replaced. Therefore, regardless of the steering mode at the end of the work and the turning work of the front and rear wheels, there is a technical problem to be solved in order to switch to the steering mode set by the switching switch at the time of power-on. It is an object of the present invention to solve this problem.

[Means for Solving the Problems]

The present invention has been proposed in order to achieve the above object, and a steering cylinder is attached to each of the front and rear drag arms, and both the front wheel and the rear wheel are formed to be steerable,
In a powered vehicle running in various steering modes, a means for detecting the steering angles of the front wheels and the rear wheels is provided, and when the power is turned on, the steering mode is determined from the detected values of the respective steering angles, and the set steering mode is determined. In comparison, when the two are different, the present invention provides a four-wheel steering control device provided with a control unit that operates the direction switching valves of the front and rear steering cylinders so as to correspond to the set steering mode. . [Operation] The steering angle of the front wheels and the rear wheels is detected by the steering angle detecting means, and it is monitored how many times the respective wheels turn left or right. The steering angle data of the front wheels and the rear wheels at that time is sent to the control unit, and the control unit determines which steering mode is in accordance with the data, and determines whether the steering mode is in front or rear so as to correspond to the determined steering mode. Controls the direction switching valve of the steering cylinder. Then, the current steering mode set by the switching switch is read, and when both are different from the determined steering mode, the front and rear steering modes are set so as to be in the steering mode set by the switching switch. Operate the direction switching valve of the cylinder. Therefore, the switching operation can be performed to the steering mode set at the time of power-on, regardless of the turning positions of the front wheels and the rear wheels. 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 working machine (29) such as a rotary is attached to a rear portion of the riding management machine (1) via a link mechanism (28), and lift cylinder (30) is operated by pressure oil from the main control valve (27). ) (30) is operated, and the ground work machine (29) is raised and lowered. FIG. 3 shows a hydraulic circuit and an oil tank (31).
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. The pressure oil branched from the flow divider (32) is sent to the main control valve (27) by pressure to operate the lift cylinders (30) (30). FIG. 4 shows a state of the rear wheel steering mode (mode 2).
The solenoid (B) of the direction switching valve (25) is turned on and moves to the position b of the spool, and the solenoid (C) of the direction switching valve (26) is turned on and moves to the position of the spool c. ing. 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 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. Next, a control method for switching the steering mode will be described in detail. As shown in FIG. 8, the front wheel (4) (4) as the reference line (0) when the straight-ahead position, the front-wheel steering angle when the reference line is EKO rightward theta _F is positive, the left front-wheel steering angle theta _F a while Eko to have a negative side. Similarly, as the rear wheels (14) (14) the reference line when the straight traveling position (0), when you are Eko to the right from the reference line rear wheel steering angle theta _R is positive, to the left the rear wheel steering angle theta _R is a minus side while EKO. Therefore, the front wheel steering angle θ _F is in the range from the plus side maximum steering angle + θ _Fmax to the minus side maximum steering angle −θ _Fmax , and the rear wheel steering angle θ _R
Is in the range from the maximum steering angle + θ _Rmax on the plus side to the maximum steering angle −θ _Rmax on the minus side. When the passenger management machine (1) is powered on, the potentiometer (1)
At 0) and (20), the front wheel steering angle θ _F and the rear wheel steering angle θ _R
According to the program set in the CPU in advance,
At that time, it is determined which steering mode is set. Attached Table 1 shows criteria for determining which steering mode is based on the detected values of the steering angles θ _F and θ _R of the front wheels and the rear wheels. For example, the front wheel steering angle θ _F is on the plus side and the rear wheels are if the steering angle theta _R is 0, it is determined that the CPU is in the state of the front wheel steering mode (mode 1). Then, according to a command from the control unit, all the solenoids of the direction switching valves (25) and (26) are turned off, and the spools are respectively set to the n position. Even when the front-wheel steering angle theta _F and a rear wheel steering angle theta _R showed other detection values, by the applicable range of the detection value of each shown in Appendix 1 is steered mode discrimination, is the determination steering Activate the solenoid corresponding to the mode. Therefore, even if the steering is operated in the power-off state after the work is completed and the front wheels or the rear wheels are in the turning positions in another steering mode, the steering angles θ _F of the front wheels and the rear wheels are set. , θ
Each solenoid is turned on / off in accordance with the steering mode determined based on the detected value of _R , and the direction switching valves of the front and rear steering cylinders are controlled. Figure 9 is a flow chart showing the operation to detect the front-wheel steering angle theta _F and a rear wheel steering angle theta _R at power on a riding tiller (1) (step). In the step, θ
_F is on the plus side and θ _R is on the minus side, or θ
_F is led to the step when the minus side and theta _R is positive, the solenoid (B) is turned on is determined to mode 4. Proceeds from step to step, theta both _F and theta _R is led to the step when both are negative when a positive, mode 3 a determination has been solenoid (A) is turned on. Proceeding from step to step, when θ _F = 0 and θ _R is on the plus side,
Alternatively, when θ _F = 0 and θ _R is on the negative side, the process proceeds to step S, where the mode 2 is determined and the solenoid (B) is used.
And (C) are turned on. When the answer is No in step, the process proceeds to step 1, where mode 1 is determined, and all the solenoids are turned off. Then, the determined steering mode is set to M _A
Stores in (step), and then stored in the M _B read the mode that has been set in the steering mode switching switch (step). Both it is determined whether the same value to compare the M _A and M _B in step, if not identical controlled operating each solenoid to switch the mode set by the steering mode switching switch program Ends. The mode switching in the above steps is performed by the operator using the front wheels (4) and (4).
This is automatically performed by steering the rear wheels (14) and (14) in a straight traveling state. 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 those modified. [Effects of the Invention] As described in detail in the above-described embodiment, the present invention determines the steering mode from the detected values of the steering angles of the front and rear wheels, and determines whether the steering mode is different from the steering mode set by the switching switch. Switch to the set steering mode. For this reason, even when the steering is operated in the power-off state after the work is completed, or when the switching switch is switched to another steering mode, at the time of power-on, the steering mode is switched to the steering mode set by the switching switch. Therefore, regardless of the steering mode at the end of the work and the turning positions of the front and rear wheels, the steering mode can be changed to an arbitrary steering mode at the time of power-on, which contributes to improvement of operability at the time of power-on.

[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 flowchart for explaining the steering angle of the rear wheels, and FIG. 9 is a flowchart. (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 θ _F … front wheel steering angle, θ _R … rear wheel steering angle (A) (B) (C)… solenoid

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B62D 6/00 B62D 7/14

Claims (1)

(57) [Claims] 1. A steering cylinder is attached to each of front and rear drag arms, and both front wheels and rear wheels are formed so as to be steerable. In a powered vehicle running in various steering modes, steering angles of front wheels and rear wheels are determined. A detecting means is provided, and when the power is turned on, the steering mode is determined from the detected values of the respective steering angles, and compared with the set steering mode. If the two are different, the two correspond to the set steering mode. A four-wheel steering control device comprising a control unit for operating a direction switching valve of a front and rear steering cylinder.