JPH03213467A - Four-wheel steering system in power vehicles - Google Patents

Abstract

PURPOSE:To improve safety during running at a high speed by mounting cylinders for steering on front and rear drag arms and providing a control part to effect switching to a front wheel steering mode when it is detected that a shift lever is located in a high speed running position. CONSTITUTION:Final cases 3 are mounted on the right and lefts of a front shaft 2 of a riding managing machine 1 to transmit a drive force to both sides of a front axle 4. The one end part of a drag link 6 having the other end part coupled to a drag arm 7 positioned to a central part is coupled to a knuckle arm 5 protruded to a final case 3. A steering mechanism for a rear axle 12 is formed in a similar manner described above, front and rear wheels are independently steered through operation of cylinders 9 and 19 for steering coupled to drag arms 7 and 17. In this case, a sensor 31 for detecting a shift position is mounted on a shift lever, and control is executed such that, when it is detected by the sensor 31 that the shift lever is located in a high speed running position, a front wheel steering mode is selected.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a four-wheel steering system in a power vehicle, and in particular to a control system that restrains four-wheel steering when the gear shift lever is in a high-speed position. The present invention relates to a four-wheel steering system equipped with a four-wheel steering system.

[Prior Art] Recently, an increasing number of power vehicles such as passenger management machines, tractors, etc. have both front wheels and rear wheels that can be freely steered. Many of these have a mechanical configuration in which four-wheel steering is switched by a combination of gears so that only the front wheels, only the rear wheels, or both front and rear wheels can be steered. In addition, a hydraulic configuration in which the front and rear track arms are rotated by hydraulic cylinders has also been proposed.

[Problems to be Solved by the Invention] The above-mentioned four-wheel steering system is switched by fixing the front and rear wheels on the side that is not being steered in a straight-ahead state. Changing the steering mode may cause an accident.

Furthermore, high-speed driving in rear-wheel steering mode or four-wheel steering mode is dangerous, and it is necessary to switch to front-wheel steering mode when driving on the road.

Therefore, a technical problem arises that must be solved in order to prevent switching to rear-wheel steering and four-wheel steering during high-speed driving and to achieve safe driving.The present invention solves this problem. The purpose is to

[Means for Solving the Problems] The present invention was proposed to achieve the above object, and provides a power vehicle in which both the front wheels and the rear wheels are formed to be freely steerable. A steering cylinder is attached, and a sensor for detecting a shift position is provided on the gear shift lever, and a control unit is provided in the CPU to switch to front wheel steering mode when the sensor detects that the gear shift lever is in a high speed traveling position. It is an object of the present invention to provide a four-wheel steering system for a power vehicle characterized by the following features.

[Operation] When the gear shift lever is shifted to the high-speed traveling position, the shift position detection sensor detects the shift of the gear shift lever and transmits the information to the CPU, and the control unit determines that the power vehicle is in the high-speed traveling state. . In such a case, a command is transmitted from the control section to each steering cylinder, the rear wheels are fixed in a straight-ahead state, and only the front wheel steering cylinders are operated, and the power vehicle enters the front wheel steering mode.

[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 (1), 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 (/l) (/l). Knuckle arm (S) (5) is protruded from case (3) (3) and drag link (6) (6)
Connect one end of the drag link (6) (6
) is connected to the track arm (7) provided approximately at the center of the front ■IX wheel (2). This track arm (7) is horizontally rotatable around a pin (8), and has a front end (9a) of a steering cylinder (9) on its negative side.
Concatenate. Further, a sensor (10) for detecting a rotational position, which will be described later, is provided at the front of the central portion of the track arm (7), and detects that the track arm (7) is in a left-right neutral position.

On the other hand, the rear axle (
121 (In the same way as the front wheels (4) (/l) on the left and right sides, install the final case (1st class (1) to transmit the driving force to the left and right rear wheels (1/I) (Δ). , the final case (1■(1 → knuckle arm (lE9(+
5i) to connect the negative end of the drag link (160I6), and connect the other end of the drag link (160+6) to the track arm (r7) provided approximately at the center of the rear wheel (121). Furthermore, connect the rear end (+98) of the steering cylinder θ9 to the - side of the track arm (r?) that can freely rotate around the center of the pin, and A sensor (20) for detecting rotational position is provided at the front.

In addition, an orbit roll (a) is provided at the rotating base of the steering wheel (21), which feeds pressure oil from the hydraulic pump (c) to the direction switching valve) and (c), and also to the chassis (l + ) Pressure oil is also fed under pressure to the main control valve (4) installed at the rear of the main control valve (4). A ground work machine (A) such as a low crane is attached to the rear of the passenger management machine (1) via a link mechanism Q71, and a lift cylinder (A) ( (g) is activated, and the ground working machine (a) is moved up and down.

A sensor C1+) for detecting a shift position is provided on the shift lever (1) to detect whether or not the shift lever [C] has been shifted to the high-speed traveling position. Although not shown, there are cases where a sub-shift lever is provided outside the main shift lever, and in such cases, the sensor C31) is placed at the high speed position of the sub-shift lever.
may be provided. Furthermore, a sensor (c) for detecting pedal operation is provided on the foot accelerator (a) so that the operation of the foot accelerator 0 can be detected.

Fig. 3 shows a hydraulic circuit, in which pressure oil is sent under pressure from an oil tank (b) to an orbit roll (2) by a hydraulic pump (c), and the rotation direction and rotation angle of the steering wheel (21) are adjusted. According to the pressure oil, the track number (le)
Or, it is forced to be sent from the track (L) to the direction switching valve (T) and (G). Each direction switching valve (g)) (c) moves the spool (not shown) by turning on and off the solenoid (S I) (52) (S3), switches the direction of the pressure oil, and connects the steering cylinder ( 9) Force feed to (one). Third
The state shown in the figure is each solenoid (S I) (52)
(53) are all turned off, and the vehicle is in front wheel steering mode. For example, if the steering wheel 121) is rotated clockwise, the pressure oil flows from the turn (lj) through the direction switching valve (g)) to the turn (9b) of the steering cylinder (9).
Press the piston (9c) backward to return to the direction switching valve (from the track (9d)). Furthermore, the pressure oil is sent under pressure to the direction switching valve (c), but since the solenoids (52) and (53) are off, the pressure oil is not sent under pressure to the steering cylinder θ9), and the orbit roll (track number 221) Return to (I,). Therefore, the track arm (7) rotates clockwise in the figure around the pin (8), and the front wheel (/I) (4) rotates as shown by the chain line. The passenger management machine (1) turns to the right. Also, the pressure oil branched from the flow divider (c) is sent under pressure to the main control valve (a), and the lift cylinder (29) (
b) is activated.

Figure 4 is a block diagram of the electric circuit, and shows the switch (SW
I) is front wheel steering mode, switch (SW2) is rear wheel steering mode, switch (SW3) is same phase four wheel steering mode,
The switch (SW4) is a changeover switch to the reverse phase four-wheel steering mode, and the lamps (p+-1) (PI, 2) (PL)
3) (PL4) is an indicator lamp for each switched mode. Also, the code (“P”) is the sensor (io) on the front wheel side.
The operating ramp (IMP) is the sensor G on the rear wheel side! O) is an operating lamp, and (nz) is a buzzer. and,
In addition to the automatic control circuit for the four-wheel steering mode mentioned above, there are switches for manual switching (SW5) (SW&) (SW7) (
SW8) is provided.

These signals are sent to the CPU (
3i, and each solenoid valve (Sl) (52
) (S3) to turn the solenoid on and off.

In addition, sensors (10) and (a) for detecting rotational positions are provided at the center of the front and rear track arms (7) and (r'?).
, and the sensor 01 for detecting the shift position provided on the gear shift lever (c) and the sensor (c) of the foot accelerator (to) are connected to the CPU @ via the A/D converter (4 [phase]), respectively. has been done.

Figure 5 shows the state of the rear wheel steering mode, and shows the solenoid (5
1) and (S2) are turned on and the spool is moving. For example, if the steering wheel (01) is rotated clockwise, pressure oil is sent from the track (1?) to the direction switching valve (), but since the solenoid (Sl) is on, the steering cylinder (9) Pressure oil is not sent under pressure to the steering cylinder (one) through the direction switching valve (c).
Pressure oil is forced into the cylinder from 9b), and the piston (1
9C,) is pushed forward to be discharged from the track (1!ld) to the direction switching valve (c), and return to the track (L) of ) in the orbit roll. Therefore, the track arm (■ is the pin (
The rear wheels (+4) (
1/I) or turn around as shown by the chain line and press the passenger control machine (1).
turns to the right.

FIG. 6 shows the state of the same-phase four-wheel steering mode, in which the solenoid (51) and (S2) are turned off and at the same time, the solenoid (S3) is turned on, and the direction switching valves (271) and (c) are switched. Therefore, the steering wheel (
21) clockwise, the front wheel (4) (/I)
At the same time, the rear wheels 04) (1/I) turn clockwise in the same phase as shown by the chain lines, and the passenger management machine (1) moves diagonally to the right. Further, FIG. 7 shows the reverse phase four-wheel steering mode, in which only the solenoid (S2) is turned on and the direction switching valve (c) is switched. Therefore, if the steering wheel (21) is rotated clockwise, the front wheels (4) (
4) and the rear wheels (14) (1/I) turn in opposite phases, and the passenger management machine (1) turns to the right.

Here, to explain the sensors 00) and (c), body protrusions (7a) and (17a) are provided protruding from the front center of each track arm (7) and (b) as shown in FIG. A sensor (10) consisting of a micro switch etc. is installed in front of the center of each track arm (7) and (r71).
and (a) are fixed. Therefore, when each track arm (7) or (r7) is in the left/right neutral position, the protrusion (7a) or (17a) respectively contacts the sensor (10) or the microswitch contact of QΦ. Press and CPU0'3
The control unit (a) detects that the track arm (7) or (r7) is in the neutral position.

On the other hand, the sensor (3+) transmits a signal to the CPU (3'i3) when the gear shift lever (1) is shifted to the high-speed traveling position, and controls that the passenger management machine (1) is in the high-speed traveling state. The sensor (c) sends a signal to the CPU (3) when the foot accelerator (a) is depressed.
'i5, and the control unit (
b) is detected.

Next, the operation of the electric circuit and hydraulic circuit will be explained according to the flowchart shown in FIG. First, in step (2), the control section (a) determines whether the shift lever (a) is in the high speed position based on the detection by the sensor (31), and if it is in the high speed position, the process proceeds to step (2). In step ■, the sensor (
Based on the detection of c), it is determined whether the foot accelerator (a) is depressed or not, and when the foot accelerator (b) is depressed and the vehicle is running at high speed, the process proceeds to step (iii). In step ■, it is determined whether the switch (SWI) or (sw5) is on or not. If it is off, the process goes to step ■; if it is on, the solenoid ( Sl) (5
2) ('S3) are all turned off and the front wheel steering mode shown in FIG. 3 is entered. That is, when the passenger management machine (1) enters a high-speed running state while remaining in another steering mode in steps (2) and (3), it immediately changes to the front wheel steering mode.

On the other hand, in step ■, switch (SW2) or (SW6
) is on or not, and if it is off, go to step ■, and if it is on, go to step ■ to turn on the solenoid (
SIH, S2) is turned on to enter the rear wheel steering mode shown in FIG. In step ■, it is determined whether the switch (SW3) or (SW7) is on, and if it is off, the process goes to step ■; if it is on, only the solenoid (S3) is turned on in step ■, and the sixth The system enters the same-level four-wheel phase steering mode shown in the figure. Furthermore, in step ■, it is determined whether the switch (SW4) or (SW8) is on, and if it is off, the process returns to step ■, and if it is on, only the solenoid (S2) is turned on in step [phase]. As a result, the reverse phase four-wheel steering mode shown in FIG. 7 is entered.

When the above-mentioned steering mode is switched, the mode switching is performed after the wheels on the non-steering side are returned to the straight-ahead state and fixed by the detection of sensors 00) and (a), and if the steering mode does not return to the straight-ahead state, the buzzer (17) is activated. Alternatively, a warning signal is issued by displaying a lamp or the like. Also, in order to be able to drive in a mode other than the front wheel steering mode when driving at high speeds, when the other steering mode switch is turned on in step
Alternatively, the setting may be made such that step (2), step (2), or step [phase] is reached after issuing a warning signal such as a lamp display.

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 described in detail in the above-mentioned embodiment, in this invention, when the power vehicle is running at high speed, the rear wheels are fixed in a straight-line state and only the front wheels can turn. Due to this error, the vehicle is forcibly switched to front wheel steering mode even if the vehicle is still driving in another steering mode. Therefore, steering performance during high-speed running is stabilized, and inadvertent switching to another steering mode is prevented.

In this way, the invention can restrain steering switching without complicated operations and contribute to improving safety during driving.

[Brief explanation of drawings]

The figures show one embodiment of the present invention, and Fig. 1 is a side view of the passenger management machine, Fig. 2 is an explanatory view showing the same plane, and Fig. 3 is a side view of the passenger management machine.
Figure 4 is a hydraulic circuit diagram for front wheel steering mode, Figure 4 is a block diagram of the electrical circuit, Figure 5 is a hydraulic circuit diagram for rear wheel steering mode, Figure 6 is a hydraulic circuit diagram for same-phase four-wheel steering mode, and Figure 7 is a hydraulic circuit diagram for front wheel steering mode. The figure is a hydraulic circuit diagram of the anti-phase four-wheel steering mode, and FIG. 8 is a flowchart. (1)・・・Passenger management machine (4)・・・・・・
・Front wheel (7) (+7)...-Track arm (
9) (+9)... Steering cylinder Q (10) (20) (3+) @... Sensor (a)
...... Gear shift lever (A) ... Control section (17I) ... Rear wheel 0 - ... CPU A - JP-A-3 213467 (7) 415

Claims (1)

[Claims] In a power vehicle in which both the front and rear wheels are configured to be freely steerable, steering cylinders are attached to the front and rear track arms, and a sensor for detecting the shift position is provided on the gear shift lever, and the sensor detects the gear shift lever. CP controls the control unit that switches to front wheel steering mode when it detects that it is in a high-speed driving position.
A four-wheel steering device for a power vehicle, characterized in that it is provided in a U.