JPH05103507A - Apparatus for adjusting gravity center of tractor - Google Patents

Abstract

PURPOSE:To optimize the distribution of load on the front and the rear wheels and to correct the position of gravity center by shifting a weight in machine direction with an actuator corresponding to the variation of the load distribution between the front wheel and the rear wheel. CONSTITUTION:A lift arm angle sensor 41, a liquid level sensor 42 and a position lever 15 are connected to a controller and a servo-motor is controlled according to the variation of the load distribution ratio between the front wheels 2, 2 and the rear wheels 3, 3. The servo-motor drives a pump and transfers liquid between tanks 20, 21 to adjust the position of the gravity center.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a center-of-gravity position adjusting device for a tractor which adjusts the center-of-gravity position forward and backward so that a load is always shared by a front wheel and a rear wheel in an appropriate ratio.

[0002]

2. Description of the Related Art A tractor is provided with a 3P hitch or a 2P hitch so that a working machine can be mounted on a rear side of a machine body so as to be able to move up and down. When working, the working machine is lowered and grounded in the field, and when not working such as traveling on the road, the working machine is lifted upward.

[0003]

In the tractor having the above-described structure, when the working machine is lifted, the working machine is not supported by the ground, so that the center of gravity of the entire body moves rearward. Then, the ratio of the load carried by the front wheels decreases, and in soft soil such as a wet field, the rear wheels dive into the soil or mud, which causes a problem in running. In addition, even if it is not soft soil, the front wheels float up from the ground and become
There were problems such as the front wheels slipping at the time of starting and the like, and the straight running performance deteriorated during running. These phenomena become remarkable when the working machine is heavy such as a rotary tiller.

[0004]

In order to solve the above problems, the present invention has the following constitution. That is, the center-of-gravity position adjusting device for a tractor according to the present invention is a tractor in which a working machine can be mounted up and down in the rear of a machine body, a weight having a constant weight, an actuator for moving the weight back and forth, a front wheel, and The control device drives the actuator based on a change in the ratio of the loads shared by the rear wheels.

[0005]

When the working machine is lifted, the ratio of the load applied to the rear wheels becomes larger than the ratio of the load applied to the front wheels. Based on the change in the load ratio, the actuator is driven to move the weight forward, so that the ratio of the loads shared by the front wheels and the rear wheels is adjusted appropriately.

[0006]

1 is a view showing a usage state of a tractor according to the present invention. This tractor 1 includes a pair of left and right front wheels 2, 2.
A rotary cultivator 6 is mounted as a working machine on a 3P hitch 5 provided at the rear of the machine body, which includes 2 and rear wheels 3 and 3.

The 3P hitch 5 is a pair of left and right lower links 1.
0, 10 and one top link 11 in the center, and rotary cultivator 6 at the rear end of these links 10, 10, 11.
Hitch is connected. Lower link 1 via lift rods 13 and 13 to a lift arm 12 driven by a hydraulic device.
0 and 10 are hung, and the working machine 6 is moved up and down by rotating the lift arm 12 up and down. The position lever 15 is used to lift and lower the work machine.

As a center-of-gravity position adjusting mechanism, liquid tanks 20, 21 are provided at the front end of the machine body and at the lower part of the machine body located behind the machine body.
Are provided respectively, and a fixed total amount of the weight liquid 22 is contained in both liquid tanks 20 and 21. And
As shown in FIG. 2, suction between both liquid tanks 20 and 21
A pump 23 capable of reversing the discharge direction is provided so that the liquid 22 can move back and forth. The pump 23 is driven by the forward / reverse rotation motor 24. When the motor 24 is rotated in the forward rotation direction, the liquid 22 flows from the tank 21 to the tank 20, and when the motor 24 is rotated in the reverse rotation direction, the liquid 22 is transferred from the tank 20 to the tank 21. Flowing through. As the weight liquid, a liquid having a high specific gravity, such as water, is suitable so that the capacity of the liquid tank can be small. In this example,
The liquid 22 is used as the weight, and the forward / backward movement motor 24 is an actuator for moving the liquid 22 back and forth.

Further, a liquid circuit as shown in FIG. 5 is constructed, and the liquid is circulated from the tank 21 to the tank 20 by the pump 26, and the liquid is circulated from the tank 20 to the tank 21 by its own weight. You may allow it. The solenoid valves 27 and 28 are used to switch the flow direction. In this case, at least the tank 20 needs to be provided higher than the tank 21.

Needless to say, as shown in FIG. 6, the weight-like weight 30 may be directly moved forward and backward by an actuator such as a hydraulic cylinder 31 to adjust the position of the center of gravity. Cylinder stroke sensor 32
The amount of forward / backward movement of the weight 30 is detected by. For reference, a hydraulic circuit diagram for controlling the hydraulic cylinder 31 is shown in FIG. In the figure, 33 is a pump and 34 is a solenoid valve.

The control device 40 for controlling the center-of-gravity position adjusting device is constructed as shown in the block diagram of FIG.
The lift arm angle sensor 41 is a sensor that detects the angle of the lift arm 12, and the liquid level sensor 42 is a sensor that detects the amount of liquid in the liquid tank 20.
The detection signal of 2 and the setting signal of the position lever 15 are input to the controller 43, these data are processed, and an output signal is output to the motor 24 (or the solenoid valves 27, 28 and the solenoid valve 34).

The center-of-gravity position adjustment control is performed in the order shown in the flowchart of FIG. When the detection value of the lift arm angle sensor 41 is equal to or more than a certain value, the motor 24 is normally rotated until the liquid amount in the tank 20 becomes equal to or more than the specified amount α, and the liquid 22 is caused to flow from the tank 21 to the tank 20. If the detection value of the angle sensor 41 is below a certain value, the tank 2
The motor 24 is reversely rotated until the liquid amount in 0 becomes equal to or less than the specified amount β, and the liquid 22 is flown from the tank 20 to the tank 21.
Here, α and β are numerical values determined by the type of working machine (weight of working machine), and α> β.

Based on the detection value of the lift arm angle sensor 41, a change in the ratio of the shared load of the front wheels 2 and 2 and the rear wheels 3 and 3 is judged, and the position of the center of gravity is adjusted accordingly. That is,
When the working machine 6 is hoisted, the working machine 6 is not supported by the ground and the center of gravity of the entire work moves backward, so that the weight liquid 22 is moved forward. Further, when the working machine touches the ground, a part of the weight of the working machine is supported on the ground and the center of gravity of the whole machine moves forward, so that the weight liquid 22 is moved backward. By adjusting the position of the center of gravity in this way,
The ratio of the loads shared by the front wheels 2 and 2 and the rear wheels 3 and 3 is always maintained appropriately.

FIG. 8 is a block diagram of a control device different from the above. Even if the front wheels and the rear wheels share the load at an appropriate ratio on a flat ground, the ratio will be off depending on the slope value. For example, in the case of an upward slope, the load applied to the rear wheels becomes large, which causes problems such as poor steering performance. Therefore, the control device 50 is provided with a slope sensor 51 for detecting the front-rear inclination of the tractor 1 body and is configured to adjust the center of gravity in consideration of the inclination of the ground.

As shown in FIG. 9, the lift arm angle sensor 4
The target value w _n of the liquid level sensor 42 is calculated from the detected value l _n of 1 and the detected value sp _n of the slope sensor 51, and this target value w
_n is compared with the actual detection value of the liquid level sensor 42, and output to the motor 24 so that they match each other. The calculation of the target value w _n is performed as shown in FIG. In addition, each sensor 41, 4
The detection values of 2,51 are displayed by equally dividing the entire detection range into 256. The relationship between the detection value of the sensor and the actual lift arm angle, inclination, and liquid amount is shown in FIGS.
As shown in FIG. The B value in FIG. 13 indicates an appropriate liquid amount when the tractor is horizontal and the work implement is lowered.

As described above, when the position of the center of gravity is adjusted in consideration of both the working machine position and the inclination of the ground, the front wheels 2, 2 and the rear wheels 3, 3 are more than those controlled by the control device 40.
The ratio of the shared load of will be maintained appropriately, and stable running will be possible. Since it can be considered that there is no inclination of the ground during work, control may be performed in consideration of the detection value of the slope sensor 51 only when the working machine is being lifted or when the vehicle speed is above a certain level. Good.

Instead of providing the lift arm angle sensor, the slope sensor 51 may detect that the tractor body is tilted backward, and the position of the center of gravity may be adjusted accordingly.

As a method of detecting the change in the ratio of the loads shared by the front wheels and the rear wheels, in addition to the above method,
There are methods such as directly measuring the air pressure of the wheel, measuring the rotational speed of the wheel and reading the slip ratio. In the former method, an air pressure sensor for detecting the air pressure of each wheel is provided, and the position of the center of gravity is adjusted so that the difference in air pressure between the front wheels and the rear wheels is within a certain range. Further, in the latter method, a rotation speed sensor that detects the rotation speed of each wheel is provided, and the center of gravity is adjusted so that the rotation speeds of the front wheels and the rear wheels fall within a certain range.
Needless to say, the latter method cannot be applied to a four-wheel drive vehicle.

[0019]

As described above, when the center-of-gravity position adjusting device according to the present invention is mounted on the tractor, even if the center of gravity moves back and forth due to the lifting of the working machine or the inclination of the ground, the load on the front and rear wheels is increased. Since the position of the center of gravity is corrected so that the share is always in an appropriate ratio, it is possible to always run stably.

[Brief description of drawings]

FIG. 1 is a side view of a tractor according to an embodiment of the present invention in use.

FIG. 2 is an explanatory view of a gravity center position adjusting mechanism of the tractor shown in FIG.

FIG. 3 is a block diagram of a control device of the center-of-gravity position adjusting device.

FIG. 4 is a flowchart showing the control contents of the control device shown in FIG.

5 is an explanatory diagram of a gravity center position adjusting mechanism different from the gravity center position adjusting mechanism shown in FIG. 2. FIG.

FIG. 6 is a side view of a tractor different from the tractor shown in FIG.

7 is an explanatory view of a gravity center position adjusting mechanism of the tractor shown in FIG.

FIG. 8 is a block diagram of a control device different from the control device shown in FIG.

9 is a flow chart showing the control contents of the control device shown in FIG.

10 is a flowchart showing in detail the control contents of step A in FIG.

FIG. 11 is a diagram showing a relationship between a detection value of a lift arm angle sensor and an actual lift arm angle.

FIG. 12 is a diagram showing the relationship between the detection value of the slope sensor and the inclination of the ground.

FIG. 13 is a diagram showing the relationship between the detection value of the liquid level sensor and the amount of liquid in the liquid tank 20.

[Explanation of symbols]

 1 tractor 2 front wheel 3 rear wheel 6 rotary cultivator (working machine) 12 lift arm 15 position lever 20,21 liquid tank 22 liquid for weight 23 pump 24 forward / reverse motor (actuator) 40,50 controller 51 slope sensor

Claims (1)

[Claims] 1. A tractor in which a working machine can be mounted up and down freely behind a machine body, a weight having a constant weight, and an actuator for moving the weight back and forth.
A center of gravity position adjusting device for a tractor, comprising: a controller that drives the actuator based on a change in a ratio of loads shared by the front wheels and the rear wheels.