JPH0710673B2 - Tracked vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention is a vehicle that travels on a soft land such as an agricultural vehicle, and has crawler tracks on the left and right with respect to the traveling direction. Regarding tracked vehicles.

(B) Outline of the Invention In summary, the tracked vehicle according to the present invention is left and right by a centrifugal force during a turning motion by pressing downwardly at the center of the crawler track with a pressing force equal to or less than the distributed load that acts on the crawler track when the vehicle turns. Applying a pressing force according to the change in the load distribution of the crawler track,
The vehicle is prevented from falling when the turning resistance is reduced.

(C) Conventional Technology In a vehicle that travels on a soft land such as farmland, the thrust of the vehicle can be increased by increasing the contact area of the wheels, and the straightness can be improved. Therefore, a vehicle traveling on a soft land on the road surface is provided with a crawler belt traveling device in which a crawler belt 10 is stretched over a plurality of rolling wheels 5 to 8 as shown in FIG. Rolling wheels 5-8
The thrust of the vehicle is obtained by rotating the crawler belt 10 laid over the. In this case, the crawler belt 10 is in contact with the road surface over substantially the entire bottom surface of the quadrilateral formed on the side surface thereof, thereby improving the straightness by obtaining a large ground contact area. Also, when turning to correct or change the traveling direction,
The rotation of the crawler belt on the side of the turning direction is stopped or a braking force is supplied to give a difference in rotation to the left and right crawler belts. However, when the crawler belt 10 is rotated, the larger the ground contact area is, the larger the rotation resistance becomes, and the turning operation cannot be performed smoothly.

For this reason, conventionally, the rolling wheel 5 located in the center of the crawler belt is made swingable downward from the stop position by the link 4, and the operation of the actuator such as the hydraulic cylinder 3 is supplied to the link 4 to drive the rolling wheel. There was one provided with a crawler belt pressing means for pressing the central portion of the crawler belt 10 downward by means of 5. In this way, by pressing the center part of the crawler belt 10 downward,
As shown in FIG. 9 (A), the load acting on the bottom surface 1 of the crawler belt 10 with a uniform distribution is concentrated on the center portion of the crawler belt 10 having a length l2 as shown in FIG. 9 (B). I was letting it.
As a result, when the vehicle travels straight, the hydraulic cylinder 3 is not operated, and the load is applied to the entire bottom surface of the crawler belt 10 in a substantially even distribution to increase the ground contact area. On the other hand, when turning, the hydraulic cylinder 3
Is moved in the direction of arrow B, the rolling wheel 5 is swung in the direction of arrow A to press the central part of the crawler belt 10, and the load is concentrated on that part. In this way, a tracked vehicle has been devised which increases the thrust when going straight and reduces the turning resistance when turning.

(D) Problems to be Solved by the Invention However, centrifugal force acts on the vehicle during turning,
There is a difference in the load distribution for the left and right tracks. In particular, the load acting on the crawler belt on the turning direction side becomes smaller than the load acting on straight running due to the centrifugal force, and when the center portion of the crawler belt on the turning direction side in which the load is reduced is pressed downward,
As a result, the roll of the vehicle body is promoted by the centrifugal force, and there is a risk of falling.

An object of the present invention is to provide a tracked vehicle capable of preventing a fall accident by pushing the crawler belt with a force equal to or less than a load applied to the crawler belt during a turning motion, without promoting roll of the vehicle body during a turning motion. It is in.

(E) Means for Solving the Problems A tracked vehicle according to the present invention has crawler belts on the left and right with respect to the traveling direction, and presses down the central portion of one or both of the crawler belts during a turning motion. In a tracked vehicle provided with a pressing means, the relationship between the speed detecting means for detecting the traveling speed of the vehicle and the pressing force preset below the load of the crawler belt that changes according to the traveling speed of the vehicle and the centrifugal force is shown. It is characterized in that storage means for storing and a pressing force setting means for setting the force generated by the crawler belt pressing means to the pressing force read from the storage means based on the detection value of the speed detecting means are provided.

(F) Action In the present invention, the force generated by the crawler belt pressing means for pressing the central part of the crawler belt downward during the turning motion is the pressing force read from the storage means by the pressing force setting means based on the traveling speed of the vehicle. Is set to. A centrifugal force having a magnitude corresponding to the traveling speed is generated in the vehicle in the turning motion, and the magnitude of the load acting on the crawler belt is changed by the centrifugal force. Therefore, the load acting on the crawler belt during the turning motion changes depending on the traveling speed of the vehicle. The storage means stores the relationship between the traveling speed of the vehicle and the pressing force preset below the load of the crawler belt that changes according to the centrifugal force. Therefore, at the time of the turning operation, the center portion of the crawler belt is pressed downward by a force equal to or less than the load acting on the crawler belt. By pressing the crawler belt central portion downward in this manner, load concentration occurs in that portion, and the resistance generated between the track mounting surface and the road surface due to turning decreases.
Further, at this time, since the force acting on the crawler belt does not exceed the load, the posture of the vehicle body is not deformed by this force, and the running stability is not deteriorated.

(G) Embodiment FIG. 1 is a hydraulic circuit diagram of a hydraulic device that constitutes a crawler belt pressing means included in a tracked vehicle that is a premise of the present invention.

Cylinders 3a and 3b forming part of the crawler belt pressing means are connected to a pump 2 via a direction switching valve 1. The directional control valve 1 is moved from the neutral state shown in the figure to the positions P1 and P2 by operating the steering lever 15. When the steering lever 15 is operated to the left, the directional control valve 1 is in the position P1 and the pressure oil is guided from the pump 2 to the left cylinder 3a. When the steering lever 15 is operated to the right, the directional control valve 1 is in the position P2, and the pressure oil is guided from the pump 2 to the cylinder 3b. A relief valve 14 is provided between the direction switching valve 1 and the pump 2. When the pressure oil pressure in the hydraulic circuit exceeds the set value, the relief valve 14 returns a part of the pressure oil to the tank and keeps the pressure oil pressure in the hydraulic circuit at the set value. Therefore, the pressure set by the relief valve 14 is supplied to the cylinders 3a and 3b. The setting of this pressure will be described later in the description of FIG.

When pressure oil is supplied to the cylinders 3a and 3b, the pistons 11a and 11b
Moves. The operation of the pistons 11a and 11b is performed by the rolling wheels 5 via the piston rods 12a and 12b and the links 4a and 4b, respectively.
It is transmitted to a and 5b. Now, when the steering lever 15 is operated to the left, pressure oil is guided from the pump 2 to the cylinder 3a via the direction switching valve 1, and the piston 11a and the piston rod 12a move in the direction of arrow B.

One end of the piston rod 12a is locked to one end of a link 4a whose central portion is pivotally supported by a fulcrum 9a.
When 12a moves in the direction of arrow B, the link 4a rotates in the direction of F around the fulcrum 9a. As a result, the rolling wheel 5a pivotally supported on the other end of the link 4a swings in the direction of arrow A, and the left crawler belt 10a.
Press the center part of the downward. The operation of the steering lever 15 is also transmitted to a steering mechanism (not shown). This steering mechanism stops transmission of driving force and supplies braking force to the crawler belt on the side where the steering lever 15 is operated. As for this steering mechanism, for example, the applicant of the present invention first applied for a patent application Sho 60.
The hydraulic steering device shown in -203162 can be used. That is, when the steering lever 13 reaches a predetermined intermediate position, in the hydraulic steering device, the meshing of the transmission gear between the input shaft and the left or right output shaft is disengaged, the clutch is disengaged, and the track The supply of driving force to 10a and 10b is cut off. When the steering lever moves further, the shoe is pressed against the multi-plate brake in the hydraulic steering device. As the steering lever moves, the pressing amount of the shoe against the multi-disc brake also increases, and the frictional force generated between the shoe and the multi-disc brake increases. Therefore, as the stroke of movement of the steering lever increases, the braking force that acts on the crawler belts 10a and 10b increases. This causes a difference in rotational speed between the left and right crawler belts, and the vehicle body turns in the direction in which the steering lever 15 is operated. Therefore, when the direction lever 15 is operated to the left side as described above, the transmission of the driving force is stopped and the braking force is supplied to the left crawler belt 10a, the vehicle body turns to the left side, and the center portion of the crawler belt on the turning direction side is turned. Pressed down.

FIG. 2 is a schematic front view of the tracked vehicle.

When steering straight ahead, the weight of the car body 21 is the load Wt and the tracks on the left and right
It acts on 10a and 10b almost equally, and on each track 10a and 10b
Wt / 2 load is acting. When the vehicle body turns to the left from this state, a centrifugal force F acts on the vehicle body 21 and the left crawler belt 10
The load W1 acting on a is smaller than the load W2 acting on the right crawler belt 10b. In the present embodiment, the center portion of the crawler belt on the turning direction side is pressed downward, so when turning to the left, the center portion of the left crawler belt 10a is pressed downward. When the cross-sectional area of the pistons 11a, 11b of the cylinders 3a, 3b in the hydraulic circuit shown in FIG. 1 is A, the relief valve 14 is set to a pressure of W1 / A or less. As a result, the force generated by the cylinders 3a, 3b as a pressing force becomes smaller than the load acting on the crawler belt on the turning direction side during the turning operation. The vehicle body 21 rolls due to the centrifugal force acting on the center of gravity of the vehicle body 21 during the turning operation, but since the pressing force acting on the crawler belt in the turning direction is smaller than the load acting on the crawler belt, the roll of the vehicle body 21 promotes it. Never be done. In the above embodiment, the relief valve 14 corresponds to the pressing force setting means of the present invention.

FIG. 3 is a hydraulic circuit diagram of the crawler track pressing means included in the tracked vehicle according to the embodiment of the present invention.

By operating the steering lever 15, the direction switching valve 1 selectively guides the pressure oil supplied from the pump 2 to one of the cylinders 3a and 3b. A high-speed switching valve is provided between the direction switching valve 1 and the pump 2.
31 are arranged. The high-speed switching valve 31 is brought to the position P3 by driving the solenoid SOL1 and returns the pressure oil in the hydraulic circuit to the tank.

FIG. 4 is a block diagram of a control unit of a tracked vehicle including the hydraulic circuit shown in FIG.

The CPU 41 outputs drive data to the solenoid driver 47 according to a program written in advance in the ROM 42. A tachometer 45 provided on the output shaft of the drive device outputs a pulse at a cycle corresponding to the rotation of the output shaft. The counter 46 counts the number of pulses and inputs the number of pulses per unit time to the CPU 41 as speed data. This speed data is stored in the memory area MA1 of the RAM 43. The duty ratio of the solenoid drive pulse according to the speed data is stored in the ROM 42.

During the turning operation, the CPU 41 outputs drive data to the solenoid driver 47 according to the processing procedure shown in the flowchart of FIG. That is, when the steering lever 15 is operated (n
1), Read speed data from the memory area MA1 of RAM43 (n2). The duty ratio of the drive pulse according to this speed data is selected from ROM 42 (n3), and the solenoid driver 4
Output to 7 as drive data (n4). The solenoid driver 47 drives the solenoid SOL1 based on this drive data.

The relationship between the speed data stored in the ROM 42 and the duty ratio of the drive pulse is shown by the broken line in FIG. As shown in the figure, as the traveling speed of the vehicle body 21 increases, the duty ratio of the drive pulse is increased. Therefore, the amount of pressure oil returned from the high-speed switching valve 31 increases as the speed increases. As a result, the pressure oil pressure in the hydraulic circuit shown in FIG. 3 decreases as the speed increases, as shown by the solid line in FIG.

The centrifugal force F that acts on the vehicle body 21 during the turning motion increases with the speed of the vehicle body 21, and the load that acts on the track on the turning direction side.
W1 decreases. In the tracked vehicle equipped with the hydraulic circuit shown in FIG. 3, since the pressure supplied to the cylinder 3a during the turning operation decreases with the speed of the vehicle body 21, the pressing force acting on the center part of the crawler belt on the turning direction side during the turning operation also. The speed of the vehicle body 21 decreases. As a result, the roll of the vehicle body 21 is not promoted by the crawler belt pressing means regardless of the speed of the vehicle body 21. That is, a high speed switching valve 31 is provided as a pressing force setting means in the hydraulic circuit of the crawler belt pressing means, and the duty ratio of the drive pulse of the solenoid SOL1 included in the high speed switching valve 31 is set to the vehicle body.
By changing according to the speed of 21, it is possible to press the center part of the crawler belt on the turning direction side with a pressing force according to the speed,
The steering stability of the vehicle body 21 can be favorably maintained.

When the road surface is soft, the center part of the track projects downward until it obtains a balance bearing force against the force generated by the track pressing means.At this time, the center part of the track is sunk below the road surface, so roll the car body. It never happens.

Further, in the first embodiment, the operation of the piston rods 12a, 12b of the cylinders 3a, 3b constituting the crawler belt pressing means is linked by the link 4
It was transmitted to the rolling wheels 5a, 5b via a, 4b, but in this case, the piston rods 12a, 12b side of the links 4a, 4b swing vertically as the rolling wheels 5a, 5b swing. . In this case, the cylinders 3a and 3b must be configured to be swingable, which complicates the structure. Therefore, as shown in FIG. 7, the piston rod
The rack gear 72 is formed on the 71 and the rack gear 72 is formed.
A pinion gear 74 that meshes with is pivotally supported on a support portion 77 of the case 73. Further, the rolling wheel 5 is pivotally supported by the pinion gear 74 via a connecting rod 75. With the above structure, the linear motion of the piston rod 72 in the direction of arrow G or J causes the rolling wheel 5 to swing in the direction of arrow I or J around the support portion 77 of the pinion gear 74. In this way, since the rolling wheel 5 can be moved up and down only by the linear movement of the piston rod 72, the cylinder
The 76 can be firmly fixed to the frame of the tracked vehicle. This simplifies the structure and makes the cylinder 76
Also, the piston rod 71 can be shielded from the outside, and malfunctions due to the entry of foreign matter can be prevented in advance.

(H) Effect of the Invention According to the present invention, the force generated by the crawler belt pressing means by the pressing force setting means is set to be equal to or less than the load acting on the crawler belt in consideration of the centrifugal force whose magnitude changes depending on the traveling speed of the vehicle. can do. As a result, the center part of the crawler belt can be pressed with a force equal to or less than the load applied to the crawler belt during the turning motion,
Turning resistance can be reduced without promoting roll of the vehicle body. Therefore, the turning operation can be performed smoothly without sacrificing the steering stability.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a track pressing means included in a tracked vehicle as a premise of the present invention, and FIG. 2 is a schematic front view showing a load distribution acting on a track of the tracked vehicle. 3 to 6
FIG. 1 is a diagram showing a tracked vehicle that is an embodiment of the present invention,
FIG. 3 is a hydraulic circuit diagram of the crawler track pressing means, FIG. 4 is a block diagram of the control unit, FIG. 5 is a flowchart showing a part of the processing procedure of the control unit, and FIG. 6 is a vehicle speed and hydraulic circuit. It is a figure which shows the drive duty ratio of a high speed switching valve, and the relationship with pressure oil pressure. FIG. 7 is a schematic side sectional view showing the structure of a crawler belt pressing means which can be used in a tracked vehicle including the above-mentioned two embodiments. FIG. 8 is a side view showing a track running portion of a general tracked vehicle including an embodiment of the present invention, and FIGS. 9A and 9B are loads acting on the track of the general tracked vehicle. It is a figure which shows the distribution state of. 3 …… Cylinder, 5-8 …… Roller, 10 …… Crawler track, 14 ……
Relief valve (pressing force setting means), 31 ... High-speed switching valve (pressing force setting means).

Claims (1)

[Claims] 1. A tracked vehicle having crawler belts on the left and right with respect to the traveling direction and equipped with crawler belt pressing means for pressing down the central portion of one or both of the crawler belts during a turning operation. Speed detection means for detecting speed, storage means for storing the relationship between the traveling speed of the vehicle and the load of the crawler belt that changes according to the centrifugal force, and a preset pressing force, and the force generated by the crawler belt pressing means. And a pressing force setting unit that sets the pressing force to the pressing force read out from the storage unit based on the detection value of the speed detecting unit.