JPH0249054Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a hydraulic drive device for a hydraulically driven vehicle.

(Prior Art) What is shown in FIG. 2 is a conventional hydraulic drive system for a hydraulically driven vehicle. , 2 are connected in parallel to a directional control valve 7, and each of the hydraulic motors 1, 2 is provided with the same oil discharged from a pump 8 provided in the front stage of the directional control valve 7. It is formed so that it can be simultaneously driven in both directions. Also, between the two oil supply and drainage passages 3 and 4 of the hydraulic motor 1 and the two oil supply and drainage passages 5 and 6 of the hydraulic motor 2, the other oil supply and drainage passages 3 and 4 and 5 and 6 are provided with oil. Counterbalance valves 9 and 10 are provided to allow discharged oil from the hydraulic motors 1 and 2 to flow when the pressure increases. The counterbalance valves 9 and 10 function as an automatic brake to prevent the hydraulically driven vehicle from moving forward or backward when stopped on a slope.

(Problems with the Prior Art) In the above-mentioned hydraulic drive device, oil discharged from the pump 8 is supplied to the hydraulic motors 1 and 2 at the same time, and the hydraulic motors 1 and 2 are driven simultaneously. , when only the wheel A enters the sandy ground, the hydraulic pressure required to drive the hydraulic motor 1 becomes significantly smaller than the hydraulic pressure required to drive the hydraulic motor 2, and even if only the hydraulic motor 1 is driven to rotate at high speed, the hydraulic pressure There was a problem in that the motor 2 did not rotate, and therefore only the wheels A idled and the hydraulically driven vehicle did not move.

In order to solve the above-mentioned problems, a technique is known in which a flow dividing valve is provided between the oil supply and drainage paths 3 and 5 of the hydraulic motors 1 and 2 to eliminate the difference in rotation between the left and right wheels A and B due to load fluctuations. However, in this case, oil always flows through the separation/collection valve, and the pressure loss at the separation/collection valve is large.

The present invention aims to provide a new hydraulic drive system for a hydraulically driven vehicle that solves the problem of the wheels of the hydraulically driven vehicle spinning and not moving forward or backward without using a flow dividing valve that has the problem of pressure loss. purpose.

(Means for solving the problem) In order to achieve this objective, the present invention provides a pair of hydraulic motors that drive the left and right wheels, respectively, and connects the two oil supply and drainage paths of each hydraulic motor to a directional control valve. The hydraulic motors are connected in parallel so that they can be simultaneously driven in the same direction by oil discharged from a pump provided upstream of the directional switching valve, and the two oil supply and drainage passages of each of the hydraulic motors are connected with one another, respectively. In a hydraulic drive system for a hydraulically driven vehicle, the system is provided with a counterbalance valve that allows discharged oil to flow from the hydraulic motor when the hydraulic pressure in the oil supply and discharge passage increases. A switching valve is disposed between the oil supply and drain passages, and the switching valve is switched between a regulation position that restricts the hydraulic motor from being driven by the oil discharged from the pump and a permissible position that allows the driving, and further controls the input and output of the hydraulic motor. The ports are connected by a bypass oil line equipped with an on-off valve.

(Function) With the above configuration, when one wheel enters a sandy area and spins idly, the switching valve of the oil supply/drain passage of the hydraulic motor on the side that is idling is set to a new position, and the input/output of this hydraulic motor is set to a new position. Open the on-off valve of the bypass oil passage connecting the port. The oil discharged from the pump thus constructed is supplied only to the hydraulic motor that drives the other wheel, and the hydraulic motor is driven to move the hydraulically driven vehicle. On the other hand, at this time, the hydraulic motor on the idling side is located in a closed circuit due to the opening/closing valve of the bypass oil passage, so during the movement, it rotates from the wheel side. When torque is transmitted, the wheel is rotationally driven by this rotational torque, and no slip occurs on the wheel.

(Example) Next, the present invention will be explained in detail based on FIG. 1 showing a specific example.

In this FIG. 1, symbols A, B, 1,
2, 3, 4, 5, 6, 7, 8, 9, and 10 refer to the same elements as those explained in the explanation of FIG. 2, so a new explanation will be omitted.

11 is a solenoid type switching valve provided between the oil supply and drainage passages 3 and 4, and this solenoid type switching valve 1
1 is a position that can be switched between a restriction position that restricts the hydraulic motor 1 from being driven by the oil discharged from the pump 8 and a permissible position that allows the hydraulic motor 1 to be driven; When the position is de-energized, each position is set to the allowable position. 12
is a bypass oil passage connecting the input and output ports 1' and 1'' of the hydraulic motor 1, and 13 is a solenoid-type on-off valve provided in this bypass oil passage 12.The solenoid-type on-off valve 13 is energized. At times, the bypass oil passage 12 is opened in the open position, and when power is de-energized, the bypass oil passage 12 is closed in the closed position.14 is a solenoid-type switching valve provided between the oil supply and drainage passages 5 and 6, and this solenoid The type switching valve 14 has a regulating position for regulating the hydraulic motor 2 from being driven by the oil discharged from the pump 8;
The hydraulic motor 2 is switched to a permissible position that allows the hydraulic motor 2 to be driven, and when energized, the regulating position is set, and when not energized, the permissible position is set. 1
5 is a bypass oil passage connecting the input/output ports 2', 2'' of the hydraulic motor 2, and 16 is a solenoid-type on-off valve provided in this bypass oil passage 15.The solenoid-type on-off valve 16 is as follows: When energized, the bypass oil passage 15 is opened in the open position, and when de-energized, the bypass oil passage 15 is closed in the closed position. 17 is a switch that controls switching of the spools of the solenoid type switching valve 11 and the solenoid type on-off valve 13. 18 is a switch for switching and controlling the spools of the solenoid type switching valve 14 and the solenoid type on/off valve 16.
7 and 18 are both OFF, the solenoid type switching valves 11 and 14 are in the allowable position,
and the solenoid type on-off valve 1
From where 3 and 16 are in the closed position,
In this state, when the directional control valve 7 is switched from its neutral position to the left and right positions, the hydraulic motors 1 and 2 are driven, and the hydraulically driven vehicle moves forward or backward via the wheels A and B. During the forward or backward movement, if, for example, the wheel A enters a sandy area and starts spinning and stops moving, the switch 17 is turned on, the solenoid type switching valve 11 is set to the regulation position, and the solenoid type on-off valve 13 is turned on. Open position. In this case, the oil discharged from pump 8 is
Only the hydraulic motor 2 is supplied, and the hydraulic motor 2 rotationally drives the wheels B which are not in a idling state to move forward or backward. When the rotational torque from the wheel A side acts on the hydraulic motor 1 during this forward or backward movement, the hydraulic motor 1 discharges the discharged oil to the bypass oil passage 12 side and the suction Oil bypass oil line 12
The wheels A rotate without slipping. In the above embodiment, the solenoid type switching valve 11 and the solenoid type on-off valve 13 are turned on and off by turning on and off the switches 17 and 18.
The solenoid type switching valve 14 and the solenoid type on-off valve 16 are controlled simultaneously, but two more switches are added so that the solenoid type switching valve and the solenoid type on-off valve can be controlled independently. You can. In addition, in the above embodiment, a case has been described in which the hydraulic motors for driving the left and right wheels receive hydraulic oil in parallel from the directional control valve. Of course, the invention of the present invention can also be applied to a so-called four-wheel drive system in which these hydraulic motors are supplied with hydraulic oil in parallel from the directional control valve 7.

(Effects of the invention) This invention has the effect of eliminating horsepower loss due to the separation/collection valve during normal driving because the separation/collection valve is not used. In addition, when a wheel with a small load is spinning and a wheel with a large load does not rotate and cannot move forward or backward, the pump's discharge oil is supplied only to the hydraulic motor for driving the wheel with a large load to drive the wheel. Hydraulic motors for driving wheels, which can move the vehicle forward and backward while having a small load, have the advantage of not slipping because they are rotationally driven by rotational torque from the wheels.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a hydraulic drive system for a hydraulically driven vehicle showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a conventional hydraulic drive system for a hydraulically driven vehicle. A, B: Wheels, 1, 2: Hydraulic motor, 3, 4,
5, 6: Oil supply and drainage path, 9, 10: Counter balance valve, 11, 14: Switching valve, 1', 1'', 2', 2'':
Input/output port, 13, 16: Open/close valve.

Claims (1)

[Claims for Utility Model Registration] A pair of hydraulic motors that drive left and right wheels, respectively, are provided, and two oil supply and discharge passages of each of the hydraulic motors are connected in parallel to a directional switching valve, so that each hydraulic motor is connected to the directional switching valve. The hydraulic motors are formed so that they are simultaneously driven in the same direction by the oil discharged from the pump provided at the front stage, and the two oil supply and discharge passages of each of the hydraulic motors are formed such that when the hydraulic pressure in the other oil supply and discharge passage increases, In a hydraulic drive system for a hydraulic drive vehicle, which is provided with a counterbalance valve that allows the flow of oil discharged from the hydraulic motor, the oil discharged from the pump is provided between the two oil supply and discharge passages of the hydraulic motor. A switching valve is provided that can be switched between a restriction position that restricts the hydraulic motor from being driven and a permissible position that allows the driving, and the inlet and output ports of the hydraulic motor are connected by a bypass oil path equipped with an on-off valve. A hydraulic drive device for a hydraulic drive vehicle, characterized by: