JPH0516687A - Device for operating off-road dump truck - Google Patents

Abstract

PURPOSE:To enable an off-road dump truck to smoothly run without slipping. CONSTITUTION:The output side of an engine 1 is connected to right and left rear wheels 5, 6 via a torque converter 2, a speed change gear 3 and a differential 4, and right and left motors 10, 11 for driving and rotating right and left front wheels 7, 8, and right and left hydraulic pumps 12, 13 each of which is driven by the engine 1 are provided and the right and left hydraulic pumps 12, 13 are connected in a closed circuit to the right and left motors 10, 11 by a first and a second main circuit, respectively, so that the right and left front wheels 7, 8 are driven and rotated by the right and left motors 12, 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling device for an off-road dump truck that operates at a mine or a dam construction site.

[0002]

2. Description of the Related Art A traveling device for an off-road dump truck is composed of left and right rear wheels which are rotationally driven by an engine and left and right front wheels which are in a free rotation state.

[0003]

Since the vehicle is driven by the driving force of the left and right rear wheels, the driving force shared by each wheel is small, and on a road surface where the friction of the wheels is small, an over torque is generated and the left and right rear wheels easily slip. You may not be able to drive stably.

Therefore, an object of the present invention is to provide a traveling device for an off-road dump truck, which can solve the above-mentioned problems.

[0005]

The left and right rear wheels 5 and 6 are rotationally driven by the output of the engine 1, and the left and right front wheels 7 and 8 are rotationally driven by the left and right traveling motors 10 and 11.
Left and right hydraulic pump 1 driven by 0, 11 and engine 1
A traveling device for an off-road dump truck, characterized in that the second and the third main circuits 14 and 15 are connected in a closed circuit, and the left and right hydraulic pumps 12 and 13 are variable capacity reversible hydraulic pumps.

[0006]

[Operation] Since the left and right front wheels 12 and 13 and the left and right rear wheels 5 and 6 are driven, the shared driving force per wheel is reduced, and over torque is unlikely to occur even on road surfaces with small wheel friction without slipping. You can drive stably.

[0007]

[Example] As shown in FIG. 1, the rotation of the engine 1 is transmitted to the left and right rear wheels 5 and 6 via a torque converter 2, a transmission 3, a differential 4 and the like, and the left and right front wheels 7 and 8 are steered. 9 and the left and right hydraulic motors 10, 1
The left and right hydraulic pumps 12, 13 driven by the engine 1 and the left and right hydraulic pumps 12, 13 discharge the pressurized hydraulic oil.
Supply is controlled. As shown in FIG. 2, the left and right hydraulic motors 10 and 11 and the left and right hydraulic pumps 12 and 13 are connected in a closed circuit by first and second main circuits 14 and 15, respectively.
The amount of oil flowing through the second main circuits 14 and 15 is controlled by the control valve 16 and is adjusted to the first
The second main circuits 14 and 15 are short-circuited by the bypass passage 18 provided with the bypass valve 17, and the left and right first main circuits 14 and 14 are short-circuited.
The left and right second main circuits 15 and 15 are the steering switching valve 19
Are communicated with the first and second communication passages 20 and 21, respectively, and the valves are switched and controlled by the controller 22.
The controller 22 includes the first and second rotation speed sensors 2
3, 24, the number of rotations of the left and right front wheels 7, 8, left first and second pressure sensors 25, 26, right first and second pressure sensors 27, 28
Is the driving pressure of the left and right traveling motors 10 and 11, the third and fourth rotation sensors 29 and 30 are the left and right rear wheel rotation speeds, and the steering angle sensor 31.
, The accelerator opening signal from the accelerator sensor 32, the neutral signal from the shift lever position detection sensor 33, and the engine speed from the engine rotation sensor 34, respectively. A control signal is output to 35, and a displacement / discharging direction changing signal is output to the controllers of the swash plates 12a and 13a of the left and right hydraulic pumps 12 and 13.

Next, the details of each part will be described together with the operation.
A neutral signal is output from the shift lever position detection sensor 33 by setting the transmission 3 in a neutral state, and an accelerator off signal is output from the accelerator sensor 32 by setting the accelerator opening to zero, and one of these signals is input. If so, the controller 22 determines that the vehicle is stopped, and the left and right hydraulic pumps 12,
The swash plates 12a and 13a of 13 are minimized, and the left and right control valves 16 and 16 are set to the shutoff position A,
The left and right bypass valves 17, 17 are set to the communication position B.
As a result, the amount of oil discharged from the left and right hydraulic pumps 12 and 13 is minimized and is not supplied to the left and right traveling motors 10 and 11,
The left and right traveling motors 10 and 11 are respectively in a free rotation state and the vehicle is stopped. When driving straight ahead. If the neutral signal from the shift lever position detection sensor 33 disappears, the accelerator opening signal is input from the accelerator sensor 32, and the input from the steering angle sensor 31 indicates straight travel,
The controller 22 determines that the vehicle is traveling straight, and sets the left and right control valves 16 to the communicating position C, and sets the left and right bypass valves 17 to the shutoff position D. At the same time, the left and right input from the third and fourth rotation sensors 29 and 30 are performed. The left and right hydraulic pumps 1 that calculate the vehicle speed based on the rear wheel rotation speed and match the vehicle speed based on the engine rotation speed from the engine rotation sensor 34.
The swash plate 12 is calculated by calculating the discharge oil amount per unit time of 2 and 13.
Set the angles of a and 13a. That is, the discharge amount per unit time of the left and right hydraulic pumps 12 and 13 is determined by controlling the swash plate angle based on the rear wheel rotation speed and the engine rotation speed. Since the rotational speeds of the left and right front wheels 7 and 8 are determined by determining the rotational speed of the left and right front wheels 11, the discharge amounts of the left and right hydraulic pumps 12 and 13 per unit time are adjusted so that the rotational speeds of the left and right front wheels 7 and 8 are values corresponding to the vehicle speed. By determining the swash plate angle according to the engine speed, the left and right front wheels 12, 13 are driven at the speed corresponding to the vehicle speed. This left and right hydraulic pump 1
When controlling the swash plate angle 2 and 13, first and second
The rotation speeds of the left and right front wheels from the rotation sensors 23 and 24 are fed back to the controller 22, and feedback control is performed so that the rotation speeds of the left and right front wheels become a value commensurate with the vehicle speed. Since the left and right first pressure sensors 25, 27 and the left and right second pressure sensors 26, 28 are equal in pressure when the vehicle is traveling straight ahead,
If the pressure difference between the left and right sides of the controller 22 is within the set value and the input from the steering angle sensor indicates immediately after,
Considering that the vehicle is traveling straight ahead, the steering switching valve 19 is set to the communication position E, and the left and right first and second circuits 14 and 15 are respectively communicated with each other to maintain the pressure at the same level. This stabilizes the straight running performance of the vehicle. When turning left and right. In order to turn the vehicle left and right, the steering wheels (not shown) are operated to steer the left and right front wheels 12, 13, and the steering angle sensor 31 inputs the steering angles of the left and right front wheels 12, 13 to the controller 22. The controller 22 outputs a signal for controlling the swash plate angles of the left and right hydraulic pumps 12 and 13 based on the input rudder angle to reduce the amount of oil discharged from the hydraulic pumps on the inside of the turn to smoothly turn.
At this time, when the steering angle is input to the controller 22, the control valve 16 on the inside of the turn is set to the throttle communication position F for a certain period of time to reduce the amount of oil to the traveling motor on the inside of the turn to compensate for the time delay of the swash plate angle control. And improve responsiveness.
Further, since the discharge flow rates of the left and right hydraulic pumps 12 and 13 are different, the left and right first and second pressure sensors 25, 27 and 2
Since the pressures of 6 and 28 are different, the steering switching valve 19 is set to the shutoff position G by the pressure difference, and the left and right first and second main circuits 14 and 15 are made independent.

Next, the operation when the front wheels and the rear wheels slip will be described. When either or both of the left and right rear wheels 5, 6 slip during straight running as described above. 1st, 2nd, 3rd when starting
・ The left and right front wheel rotation speeds and the left and right rear wheel rotation speeds are respectively input to the controller 22 from the fourth rotation sensors 23, 24, 29, 30 and the left and right front wheel rotation speeds are compared with the left rear wheel rotation speeds and the right rear wheel rotation speeds. Therefore, it is determined that the left and right rear wheels 5, 6 or the one or both of them slip due to the difference in the number of revolutions. As a result, a braking signal is output to the rear wheel brake solenoid 35 that is slipping to brake the slipping rear wheel, and at the same time the left and right control valves 16 and 16 are set to the throttle communication position F, and the left and right hydraulic pumps are set. By decreasing the swash plate angles of 12 and 13 to reduce the amount of discharged oil, the left and right traveling motors 1
The rotational speeds of the left and right front wheels 7 and 8 are reduced by rotating 0 and 11 at low speed. After this, when the number of rotations of the rear wheels slipping becomes the same level as the front wheels, the rear wheel brake solenoid 35
A release signal is output to release the rear wheel brake, and if no slip is detected for a certain period of time thereafter, the normal traveling control is resumed. When slip occurs on one of the left and right front wheels 12, 13. If it is determined that one of the left and right front wheels 12 and 13 has slipped according to the number of rotations of each rotation sensor input to the controller 22 as described above, the slipping side control valve 16 is closed. At the same time as A, the steering switching valve 19 is set to the shut-off position G, the control valve 16 on the non-slip side is set to the throttle communication position F, and the swash plate angle is reduced to reduce the discharge oil amount. When the rotation speed of one slipping front wheel reaches the same level as the rotation speed of the other non-slip front wheel, the control valve 16 on the slipping side is set to the throttle communication position F and the swash plate angle is reduced. Then, the discharge oil amount is reduced and the steering switching valve 19 is normally operated to travel. After this, if no slip is detected for a certain period of time, normal traveling control is restored. The above operation is shown in a flow chart in FIG.

[0010]

Since the left and right front wheels 12 and 13 are driven by driving the left and right rear wheels 5 and 6, the shared driving force per wheel is small, and over torque is unlikely to occur even on a road surface with small wheel friction and slipping does not occur. You can drive stably. The left and right front wheels 12, 13 are rotationally driven by the left and right traveling motors 10, 11, and the left and right traveling motors 10, 11 and the left and right hydraulic pumps 12, 13 are connected in a closed circuit by the first and second main circuits 14, 15. It suffices if hydraulic piping is provided between the left and right front wheels 12, 13 and the engine side, and there is no obstacle when steering the left and right front wheels 12, 13. Further, even if any three of the four wheels slip, the front wheel drive hydraulic circuit can be controlled to quickly escape.

[Brief description of drawings]

FIG. 1 is a schematic plan view of a traveling device.

FIG. 2 is a connection circuit diagram of a traveling motor and a hydraulic pump.

FIG. 3 is an explanatory diagram of a control block.

FIG. 4 is a flowchart showing the operation.

[Explanation of symbols]

1 engine, 5 left rear wheel, 6 right rear wheel, 7 left front wheel,
8 front right wheel, 10 left traveling motor, 11 right traveling motor, 12 left hydraulic pump, 13 right hydraulic pump, 14
First main circuit, 15 Second main circuit.

Claims (1)

Claims: 1. Left and right rear wheels 5, 6 are rotationally driven by the output of the engine 1, and left and right front wheels 7, 8 are left and right traveling motors 10, 11.
The left and right traveling motors 10, 11 and the left and right hydraulic pumps 12, 13 driven by the engine 1 are connected in a closed circuit by the first and second main circuits 14, 15 to rotate the left and right hydraulic pumps 12, 13 by A traveling device for an off-road dump truck, which is a variable capacity reversible hydraulic pump.