JPH0732843A - Posture control device for work vehicle - Google Patents

Abstract

PURPOSE:To provide a posture control device for a work vehicle by which the work vehicle can travel stably while holding a posture horizontally. CONSTITUTION:Hydraulic cylinders 21 and 22 are arranged between a front wheel shaft 2 and a chassis 5. An angle detector 24 is installed on the chassis 5. A hydraulic pump 20 is connected to the hydraulic cylinders 21 and 22 through an electromagnetic selector valve 23. A signal of the angle detector 24 is inputted to function generators 26 and 27 of a control part 25, and the electromagnetic selector valve 23 is switched by these output signals. When the chassis 5 is inclined forward and downward, the selection valve 23 is switched to an illustrated upper side position by a signal of the function generator 27, and pressure oil is supplied to the hydraulic cylinder 21 and 22, and the chassis 5 is raised, and becomes horizontal. When the chassis 5 is inclined forward and upward, the selector valve 23 is switched to an illustrated lower side position by a signal of the function generator 26, and the pressure oil of the hydraulic cylinders 21 and 22 is discharged, and the chassis 5 is lowered, and becomes horizontal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension system for a work vehicle used in a work vehicle that moves by wheels with tires.

[0002]

2. Description of the Related Art In a work vehicle that moves by wheels with tires, for example, a wheel shovel or a wheel loader, is an axle for driving the wheels and a vehicle body (chassis) fixed directly?
Or they are connected by a pin joint. An example of such a work vehicle will be described with reference to the drawings. 5 and 6 are side views of the schematic configuration of the wheel shovel. In each figure, 1 is a front wheel with a tire, 2 is a front axle, 3 is a rear wheel with a tire, and 4 is a rear axle. 5 is a chassis, 6 is a drive unit, 7 is a front drive shaft, and 8 is a rear drive shaft. Reference numeral 9 is an upper revolving structure which is rotatably installed on the chassis 5, and 10 is an operator's cab. Reference numeral 11 is a boom attached to the upper swing body 9, 12 is an arm attached to the boom 11, 13 is a bucket attached to the arm 12, and the boom 11, the arm 12, and the bucket 13 form a front mechanism. There is.

When the wheel excavator is running, FIG.
As shown in FIG. 5, the arm 12 and the bucket 13 are adapted to travel in a posture in which they are rolled up. In the wheel shovel, since the bucket 13 shown in FIG. 5 is a standard attachment, the bucket 13 is designed so that the loads applied to the front axle 2 and the rear axle 4 are almost equal when the bucket 13 is attached. , The wheel excavator keeps a substantially horizontal state and can run stably.

[0004]

By the way, the wheel shovel performs not only excavation work by the bucket 13 but also various other works. Therefore, various attachments such as a breaker and a crusher are used in addition to the bucket 13 depending on the work content. In this way, when an attachment other than the bucket 13 is attached,
The attachment is, as shown in FIG.
With the heavier attachment 14, the load distribution between the front axle 2 and the rear axle 4 collapses and the load distribution to the front axle 2 increases, and as a result, the deformation amount of the front wheel 1 increases as shown in FIG. Then, the car body is tilted forward. Further, in such a posture, the operator in the cab 10 leans forward together with the vehicle body and becomes unstable, which increases fatigue and may cause the operator to fall forward during sudden braking or downhill.

On the contrary, when the attachment is lighter than the bucket 13, for example, when it is a bucket for digging a narrow groove, or when the attachment is not attached, the vehicle body is lifted forward and the same as above. Cause problems.

An object of the present invention is to solve the above-mentioned problems in the prior art and to provide an attitude control device for a work vehicle capable of traveling stably.

[0007]

In order to achieve the above object, the present invention provides a front axle and wheels at both ends thereof, a rear axle and wheels at both ends thereof, and a work mechanism attached to the front axle and the rear axle. In a work vehicle including a chassis supported by, one of the front axle and the rear axle is attached to the chassis via a plurality of hydraulic cylinders, and an electromagnetic valve that drives and controls each hydraulic cylinder,
An angle detector for detecting an inclination angle of the chassis with respect to the ground, and a control unit for controlling the solenoid valve so as to hold the chassis horizontally according to a detection value of the angle detector are provided. .

[0008]

The angle detector constantly detects the ground inclination angle of the chassis (the work vehicle ground inclination angle). When the chassis tilts, the angle detector detects it, and the control unit judges the direction of the chassis tilt from the detection signal from the angle detector, and switches the electromagnetic switching valve according to this direction to switch the hydraulic oil to each hydraulic cylinder. Or to discharge pressure oil from each hydraulic cylinder.
This keeps the chassis (work vehicle) horizontal,
Stable running can be performed.

[0009]

The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a diagram showing an attitude control device for a work vehicle according to a first embodiment of the present invention. In this figure, 1 is the front wheel, 2
Is a front axle, 5 is a chassis, which are the same as those shown in FIGS. Reference numeral 20 is a hydraulic pump, and 21 and 22 are hydraulic cylinders provided between the front axle 2 and the chassis 5. In the illustrated case, the rods of the hydraulic cylinders 21 and 22 are rotatably connected to the front axle 2 and the cylinder case is rotatably connected to the chassis 5, respectively. In addition, the above-mentioned connection relation may be reversed. The rear axle 4 is directly pin-connected to the chassis 5. Reference numeral 23 is an electromagnetic switching valve interposed between the hydraulic cylinders 21 and 22 and the hydraulic pump 20.

An angle detector 24 is attached to the chassis 5. The angle detector 24 outputs a positive electric signal proportional to the tilt angle when the chassis 5 leans forward and downward, and outputs a negative electric signal proportional to the tilt angle when the chassis 5 leans forward and upward. Output. Reference numeral 25 denotes a control unit, which is composed of function generators 26 and 27 to which the detection signal of the angle detector 24 is input. As shown in the figure, the function generator 26 has the characteristic of outputting an exciting current to one solenoid of the solenoid operated directional control valve 23 only when the input signal is negative, and the function generator 27 outputs the input signal. Has a characteristic that an exciting current is output to the other solenoid of the solenoid operated directional control valve 23 only when is positive. In addition, each function generator 26,
Illustration of a converter for converting the output signal of 27 into an exciting current is omitted.

Next, the operation of this embodiment will be described with reference to the example of the wheel shovel shown in FIGS. Wheel shovel
When traveling on level ground with a standard attachment (bucket 13) attached to the tip of the arm 12,
The signal of the angle detector 24 is 0, the electromagnetic switching valve 23 is in the neutral position, and the bottom side of the hydraulic cylinders 21 and 22 is in a state in which the pressure oil that holds the chassis 5 horizontally is sealed. Therefore, the wheel excavator travels while maintaining the horizontal level.

On the other hand, when the wheel shovel attaches a heavy attachment to the tip of the arm 12, the chassis 5 tilts forward and downward, and the angle detector 24 outputs a positive signal proportional to the tilt. As a result, a signal is output from the function generator 27, and one solenoid (upper side in the drawing) of the solenoid operated directional control valve 23 is excited to activate the solenoid operated directional control valve 23.
Is switched to the upper position in the figure, and the hydraulic cylinders 21, 2
Further, pressure oil is supplied to 2, the rod extends, and the chassis 5 is lifted. When the chassis 5 is lifted, the angle detector 24 detects it in the horizontal position,
The output of the signal from the function generator 27 disappears, and the electromagnetic switching valve 23 returns to the neutral position. In this state, the wheel shovel is held horizontally and it is possible to run in the horizontal state.

Contrary to the above, if the wheel shovel has an attachment lighter than the standard attached to the tip of the arm 12, or if the attachment is not attached, the chassis 5 tilts forward and upward, and the angle detector 24 indicates that A negative signal proportional to the slope is output. As a result, a signal is output from the function generator 26 and the electromagnetic switching valve 2
3 is switched to the lower position, and each hydraulic cylinder 21, 2
The pressure oil on the bottom side of 2 is discharged to the tank, the rod contracts, the chassis 5 descends, and the angle detector 24 detects this at a horizontal position, and the signal output from the function generator 26 disappears. The electromagnetic switching valve 23 returns to the neutral position, the wheel shovel is held horizontally, and the vehicle can run in the horizontal state. Even when the wheel shovel is on a slope, the above operations are similarly performed after the angle detector 24 detects the tilt due to the tilt of the chassis 5.

As described above, in this embodiment, the angle detector 2
Since the inclination of the chassis 5 is detected by means of 4 and the solenoid directional control valve 23 is switched accordingly to control the hydraulic cylinders 21 and 22, the wheel shovel can be held horizontally, which results in operator fatigue. Except for, and stable running becomes possible.

In the description of the present embodiment, the wheel shovel has been described as an example, but it is obvious that it can be applied to other work vehicles. Further, in the description of the above embodiment, an example in which two hydraulic cylinders are provided between the front axle 2 and the chassis 5 has been described, but three or more hydraulic cylinders may be provided, and further, the rear axle 4 and the chassis 5 may be provided. It can also be provided between. Further, the angle detector 24 may be a place other than the chassis 5 as long as it can detect the inclination of the vehicle body.

FIG. 2 is a diagram showing a part of the attitude control device for a work vehicle according to the second embodiment of the present invention. In this figure, the same parts as those shown in FIG. 1 are designated by the same reference numerals. Three
Reference numerals 0 and 31 are poppet type switching valves. In the embodiment shown in FIG. 1 and this embodiment, the former uses a normal electromagnetic switching valve 23, while the latter uses a poppet type switching valve 30, 31.
The only difference is that is used, and the other configurations are the same.

When a signal is output from the function generator 26, the poppet type switching valve 31 is switched, the rods of the hydraulic cylinders 21 and 22 are contracted to lower the chassis 5, and a signal is output from the function generator 27. Then, the poppet-type switching valve 30 is switched and the rods of the hydraulic cylinders 21 and 22 are extended to lift the chassis 5 and hold the respective horizontal positions. In addition to the effect of the previous embodiment, the effect of the present embodiment uses the poppet type switching valves 30 and 31, so that the amount of leak from the valve is small, and thus the horizontal posture can be more reliably maintained. It also has the effect.

FIG. 3 is a view showing a part of the attitude control device for a work vehicle according to the third embodiment of the present invention. In this figure, the same parts as those shown in FIG. 1 are designated by the same reference numerals. Two
5A is a control unit corresponding to the control unit 25 shown in FIG.
Further, 26A is a function generator corresponding to the function generator 26 shown in FIG. 1, and 27A is a function generator corresponding to the function generator 27 shown in FIG. 1. The function generator shown in FIG. Different characteristics. That is, the function generators 26A and 27
A has a characteristic that the signal is not output immediately when the tilt occurs, but the signal is output only when the tilt is more than a predetermined angle from the horizontal position. As a result, in the present embodiment, the dead zone Δθ as shown is set.

The operation of this embodiment is similar to that of the first embodiment. In addition to the effect of the first embodiment, the effect of the present embodiment prevents the phenomenon that the electromagnetic switching valve 23 is constantly switched near the horizontal position by the setting of the dead zone Δθ and the chassis 5 vibrates in small steps. The effect that the operator's discomfort can be eliminated is also obtained.

FIG. 4 is a diagram showing a part of the attitude control device for a work vehicle according to the fourth embodiment of the present invention. In this figure, 2
Reference numeral 4 is the same angle detector as that shown in FIG. 1, 25B is a control unit corresponding to the control unit 25 shown in FIG. 1, and 40 is a proportional solenoid valve. In the control unit 25B, 26B is a function generator corresponding to the function generator 26 shown in FIG. 1, and 27B is a function generator corresponding to the function generator 27 shown in FIG. It has different characteristics from the function generator. That is, both the function generators 26B and 27B have a characteristic that a signal proportional to the absolute value of the input signal is output.

The operation of this embodiment is different from the operation of each of the previous embodiments, the signals output from the respective function generators 26B and 27B are signals proportional to the inclination of the chassis 5, and the proportional solenoid valve 40 operates in accordance with the respective operations. The driving is controlled to an opening degree according to the signals of the function generators 26B and 27B. As a result, this embodiment is
In addition to the effect of the embodiment described above, there is an effect that the horizontal posture can be controlled more smoothly.

[0022]

As described above, according to the present invention, one of the axles is attached to the chassis via a plurality of hydraulic cylinders, and the ground inclination angle of the chassis is detected by the angle detector.
The solenoid valve that drives and controls each hydraulic cylinder according to the detected value is controlled to hold the chassis horizontally, so that the work vehicle can be held horizontally, which eliminates operator fatigue. In addition, stable running can be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing an attitude control device for a work vehicle according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a part of an attitude control device for a work vehicle according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a part of an attitude control device for a work vehicle according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a part of an attitude control device for a work vehicle according to a fourth embodiment of the present invention.

FIG. 5 is a side view of the wheel shovel.

FIG. 6 is a side view of the wheel shovel.

[Explanation of symbols]

 1 Wheel 2 Front Axle 5 Chassis 23 Electromagnetic Changeover Valve 24 Angle Detector 25 Control Unit 26, 27 Function Generator

Claims (4)

[Claims] 1. A work vehicle including a front axle and wheels at both ends thereof, a rear axle and wheels at both ends thereof, and a chassis having a work mechanism attached thereto and supported by the front axle and the rear axle, wherein the front axle and One of the rear axles is attached to the chassis via a plurality of hydraulic cylinders, and an electromagnetic valve that drives and controls each of the hydraulic cylinders,
An angle detector for detecting an inclination angle of the chassis with respect to the ground, and a control unit for controlling the switching valve so as to hold the chassis horizontally according to a detection value of the angle detector are provided. Attitude control device for work vehicles. 2. The attitude control device for a work vehicle according to claim 1, wherein the solenoid valve includes two switching valves of a poppet type. 3. The posture control device for a work vehicle according to claim 1, wherein the control unit has an output characteristic having a predetermined dead zone before and after a detected value of the horizontal posture of the angle detector. . 4. The solenoid valve according to claim 1, wherein the solenoid valve is a proportional solenoid valve, and the controller has an output characteristic of outputting a signal proportional to an absolute value of a detected value of the angle detector. An attitude control device for a work vehicle, comprising: