JPH0443169A - Power vehicle steering system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a four-wheel steering control device, and in particular, it controls the amount of change in the steering angle of wheels corresponding to the steering angle of a power vehicle when moving forward. The present invention relates to a four-wheel steering control device that is different when moving backward.

[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, when a long boom is protruded to the side of the vehicle, as in the case of pest control work, it is not easy to turn, so when the powered vehicle advances to one end of the field in front wheel steering mode, it does not turn there and remains at the other end of the field. Drive backwards to the end. In such cases, the system switches to rear wheel steering mode to stabilize steering.

[Problems to be Solved by the Invention] As mentioned above, when working with a powered vehicle traveling in reverse, the worker operates the steering wheel with one hand while turning his or her head backward, so it is difficult to hold the steering wheel sufficiently. The vehicle is meandering without any movement.

Therefore, a technical problem arises that must be solved in order to facilitate steering operation when traveling backwards, and the present invention aims to solve this problem.

[Means for Solving the Problems] This invention has been proposed to achieve the above object, and includes attaching steering cylinders to the front and rear drag arms, respectively, so that both the front wheels and the rear wheels can be freely steered. In a powered vehicle, a means for detecting the steering angles of the front wheels and rear wheels, a means for detecting the steering angle of the steering wheel, and a means for detecting the forward/reverse shift position are provided to correspond to the steering angle of the steering wheel. Provided is a four-wheel steering control device characterized in that the amount of change in the steering angles of front wheels and rear wheels is smaller when shifted to a forward traveling position than when shifted to a reverse traveling position. This is what I am trying to do.

[Operation] The means for detecting the forward/reverse shift position determines whether the powered vehicle is traveling forward or backward. Further, the means for detecting the steering angle of the steering wheel detects how many times the steering wheel is turned in either the left or right direction, and data on the steering direction and steering angle at that time is sent to the control section.

The control unit determines the amount of change in the steering angles of the front wheels and rear wheels based on the judgment data of the forward/reverse shift position and the steering data, and makes the amount of change in the steering angle smaller when traveling backward than when traveling forward. do.

Therefore, when traveling backwards, the amount of change in the steering angle of the wheels corresponding to the steering angle of the steering wheel becomes small, the responsiveness of the steering becomes slow, and meandering of the vehicle is reduced.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a side view of the passenger management machine (+), and FIG. 2 shows its plane. Final cases (3) (3) are attached to the left and right sides of the front axle (2) of the passenger management machine (1) to transmit driving force to the left and right front wheels (44 x 4), and the final cases (3) (3) knuckle arm (5)
(5) is provided protrudingly to connect one end of the drag link (6) (6), and the other end of the drag link (6) (6) is provided approximately at the center of the front axle (2). Connect to the drag 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 00) is attached to the bottle (8) as 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 (yu (
■In the same way as the front wheels (4) (4), attach the final case (11(i) to the left and right rear wheels (+4)
A drag link (lF
Connect one end of the drag link (IED) and connect the other end of the drag link (IED) to the drag arm (7) provided approximately in the center of the rear axle.
Connect the rear end (19) of the steering cylinder (G) to the negative side of the drag arm (R7), which can freely rotate around the peak, and attach the potentiometer (A) to the cylinder (G). This is a means for detecting the steering angle of the wheels (14)H.

In addition, a rotary encoder (a) is provided at the rotating base of the steering wheel (21) as a means for detecting the steering direction, and a fully hydraulic controller (a) is installed to connect the pressure oil from the hydraulic pump (b) to a direction switching valve. (c) and (to)
The main control valve Q'? is installed at the rear of the chassis θ1). ) is also pumped with pressure oil. A ground work machine (c) such as a rotary is attached to the rear of the passenger management machine (+) via a link mechanism (4), and the lift cylinder (7) ( (a) is activated, and the ground work machine (a) is configured to move up and down.

A sensor (2) for detecting the lifting position is provided on the hydraulic lever (01) that operates the lift cylinder (to), and the sensor (2) detects whether the hydraulic lever (3+) is on. In addition, a sensor (b) for detecting the shift position is provided on the forward/reverse switching lever (c) provided near the steering wheel (2+), and detects whether the forward/reverse switching lever (to) has been shifted to the reverse travel position. form in a detectable manner.

Figure 3 shows the hydraulic circuit, in which pressure oil is sent under pressure from the oil tank (g) to the hydraulic pump) to the full hydraulic controller (c), and the flow device (1) in the full hydraulic controller (c) and the oil Pass through the amount adjustment knob <Lube (B),
Depending on the steering direction and rotation angle of the steering wheel Ql), the pressure oil is fed under pressure from the oil valve (R) or the oil valve (L) to the direction switching valves (c) and (b). Each direction switching valve (C) (C) is a solenoid (A) (B)
(C) By turning on and off (D), the spool changes to s,
Move to positions b, c, and d, change the direction of the pressure oil, and forcefully feed it to the steering cylinder (9) (to). Move to either position e or f. In the state shown in FIG. 3, the solenoids (^) (B) (C) (D) are all turned off, the spool is at position n, and the front wheel steering mode (mode 1) is established. Also, the solenoid (
E) is also off, the spool is in position e, and the flow rate is fully open.

For example, if the steering wheel Q1) is steered to the right, the pressure oil is forced into the cylinder from the turn (9b) of the steering cylinder (9) through the direction switching valve (A) from the turn (R), and is pressurized into the cylinder from the turn (9b) of the steering cylinder (9). Push 9C) backwards to make oil day (9d)
Return to the direction switching valve (c). Furthermore, the pressure oil is sent under pressure to the directional switching valve (c), but the solenoid (A) (
Since B) is off and the spool is in position n, pressure oil is not sent under pressure to the steering cylinder (B) and returns to the oil position (L) of the full hydraulic controller (C). Therefore, the drag arm (η) rotates clockwise in the figure around the bin (8), the front wheels (4) (4) rotate as shown by the chain lines, and the passenger management machine (1) moves to the right. At that time, since the flow rate is fully open, the amount of change in the steering angle of the wheels is sensitive to the steering angle of the steering QO.In addition, the flow divider (
The pressure oil branched from (b) is sent under pressure to the main control valve (b), which operates the lift cylinder (to) [phase].

Fig. 4 shows the state of the rear wheel steering mode (mode 2), in which the solenoid (B) of the direction switching valve (c) is turned on and the spool moves to position b, and the direction switching valve (c) is turned on and the spool moves to position b.
4) Solenoid (C) is turned on and the spool is moved to position C. Further, the solenoid (E) is turned on, and the spool of the oil amount adjustment valve Of) moves to the position f, so that the flow rate is restricted. Here, for example, if the steering wheel 00 is steered to the right, pressure oil will be sent from the track (R) to the direction switching valve (1), but the solenoid (C) is on and the spool is in the C position. Therefore, pressure oil is not sent under pressure to the steering cylinder (9), and since the spool of the direction switching valve is in position b, pressure oil is forced into the cylinder from the steering cylinder (Ko no oil day (+9b)), and the piston Press (19C) forward and select the track (+
9d) and returns to the oil position (L) of the full hydraulic controller (to) via position b. Therefore, the drag arm (r7) rotates counterclockwise in the figure with the pin (h) as the center, the rear wheel (y) turns as shown by the chain line, and the passenger control machine (1) turns to the right. At that time, since the spool of the oil amount adjustment valve (b) is in position f and the flow rate is restricted, the change in the wheel steering angle with respect to the steering angle of the steering QO is greater than in the front wheel steering mode. The amount becomes small.

Figure 5 shows the state of the same-phase four-wheel steering mode (mode 3), in which the direction change valve solenoid (^) is turned on, the spool moves to position a, and the direction change valve (a) is turned on. Both solenoids are off and the spool is in position n. Further, the solenoid (E) is turned on and the spool of the oil amount adjustment valve (B) is at position f, so that the flow rate is restricted. Therefore, steering Q
If you steer O to the right, the drag arm (7) and (
r7) rotate clockwise in the figure, and the front wheels (4) (4
) and the rear wheels (Y) turn in the same phase as shown by the chain lines, and the passenger control machine (1) moves diagonally to the right.
Since the flow rate is restricted as in the rear wheel steering mode described above, the amount of change in the steering angle of the wheels relative to the steering angle of the steering wheel 121) is smaller than in the front wheel steering mode.

FIG. 6 shows the state of the reverse phase four-wheel steering mode (mode 4), in which the solenoid (B) of the direction switching valve (c) is turned on, the spool moves to position b, and the direction switching valve (c) is turned on and the spool moves to position b. Both solenoids in g) are off and the spool is in position n. Also, the solenoid (E) is turned off, the spool of the oil amount adjustment valve (b) moves to position e, and the flow rate becomes fully open.

Therefore, when the steering wheel 61) is steered to the right, the drag arm (η) rotates clockwise in the figure and the drag arm (B) rotates counterclockwise, causing the front wheels (4) (
4) and the rear wheels (b) and (b) turn in opposite phases as shown by the chain lines, and the passenger control machine (1) turns to the right. Since the flow rate is fully open, the amount of change in the steering angle of the wheels is sensitive to the steering angle of the steering wheel QO, as in the case of the front wheel steering mode.

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

A potentiometer 00) and a slope are provided as steering angle detection means for the front wheels and rear wheels, and the steering angle signals detected by the potentiometers 00) and (1) are A/D converted by an A/D converter. It is transmitted to the control unit via the input interface. The sensor (2) for detecting the lifting position sends a signal to the control unit when the hydraulic lever (31) is on, and the control unit detects that the ground work machine (c) is in the lifting position. In addition, the shift position detection sensor (b) sends a signal to the control unit when the forward/reverse switching lever (to) is shifted to the reverse drive position, and the control unit detects that the vehicle is in the reverse drive state. To detect.

On the other hand, a rotary encoder (a) is provided as a steering angle detection means, and the rotary encoder (to) constantly generates A-phase and B-phase pulses.

As shown in FIG. 8, when the steering wheel is turned to the right, the B-phase pulse is delayed by an A period to become a CW pulse, and the rotation direction determining circuit determines that the rotation direction is to the right. on the other hand,
When the steering wheel is turned to the left, the A-phase pulse is delayed by one period to become a CCW pulse, and the rotation direction determining circuit determines that the rotation direction is to the left. These pulse signals are transmitted to the control unit via the input interface, and the steering direction and steering angle of the steering wheel are determined by counting CW pulses or CCW pulses. Furthermore, 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 control unit via the input interface. The control section judges each signal from the input interface and outputs each solenoid (A) (B) (C) (
D) sends a control signal to turn on and off. When the steering mode is Mode 1 or Mode 4, the solenoid (E) of the oil amount adjustment valve (B) is turned off to fully open the flow rate, and when the steering mode is Mode 2 or Mode 3, the solenoid (E) of the oil amount adjustment valve (B) is turned off. Turn on to reduce the flow rate. Also, when the control unit detects that the shift position detection sensor (B) has shifted to the reverse travel position, the solenoid (E) of the oil amount adjustment valve (B) is turned on to reduce the flow rate. .

FIG. 9 shows the relationship between the steering angle of the wheels and the steering angle of the steering wheel in this embodiment.

Straight line (Ll) is when traveling forward, or mode 1 or mode 4
This shows the relationship when the flow rate of the oil amount adjustment valve (b) is fully open. At this time, the steering angle of the wheels is set to be maximum (±30°) when the steering wheel makes one rotation (360°) to the left and right from the center point of the steering wheel. On the other hand, the straight line (L2) shows the relationship when the vehicle is traveling in reverse or in mode 2 or mode 3, and when the flow rate of the oil amount adjustment valve (b) is throttled.

At this time, from the center point of the steering wheel to the left and right, 1.5
When the wheel rotates (540°), the steering angle of the wheel is maximum (±3
0°). That is, the straight line (Ll
) When the vehicle is in a straight line (L2), the amount of change in the steering angle of the wheels relative to the steering angle is smaller;
Steering response becomes slow. In this embodiment, when the vehicle is shifted to the reverse traveling position, it is controlled to automatically switch to mode 2, so when traveling in reverse, the wheels on the front side in the direction of travel of the vehicle are steered. As a result, the directionality of the steering is improved, and the responsiveness of the steering becomes slow, thereby suppressing meandering of the vehicle. or,
When set to mode 3 to prevent side-slip on slopes, the oil flow rate adjustment valve (b) is kept in a reduced state even when the vehicle is shifted to the forward travel position, and the wheels are steered according to the steering angle. The amount of change in angle is small, making it possible to make subtle adjustments to the vehicle's attitude.

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 is because the amount of change in the steering angle of the wheels corresponding to the steering angle is smaller when traveling backwards than when traveling forwards. , the steering response becomes slow when going backwards. Therefore, when driving backwards while operating the steering wheel with one hand, even if the amount of steering becomes too large,
This invention can minimize meandering of the vehicle and contribute to driving stability when traveling backwards.

[Brief explanation of the drawing]

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. FIG. 9 is a graph showing the relationship between the steering angle of the steering wheel and the steering angle of the wheels. (1)・・・・・・Passenger management machine (4)・・・・・・
・Front wheel (7) @...drag arm (9) (to)・
・・Steering cylinder 00) (G) ・・Potentiometer (B) ・・Rear wheel control---o-y re-encoder (C) (1) ・・・・Direction switching valve (to)...
...Forward/forward switching lever (b)...Sensor for detecting shift position (b)
・・・・・・Oil amount adjustment valve

Claims (1)

[Claims] A means for detecting the steering angles of the front wheels and the rear wheels, and a means for detecting the steering angle of the steering wheel, in a power vehicle in which steering cylinders are attached to the front and rear drag arms so that both the front wheels and the rear wheels can be freely steered. and a means for detecting a forward/reverse shift position, the amount of change in the steering angle of the front wheels and the rear wheels corresponding to the steering angle of the steering wheel is set to be smaller than the amount of change when the steering angle is shifted to the forward traveling position. A four-wheel steering control device characterized by a small amount of change when shifting.