JPH0245321Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a running circuit for a working machine, such as a hydraulic excavator, in which a running body is provided with an attachment (such as an earth removal plate) having an actuator.

FIG. 1 shows this type of conventional circuit for a hydraulic excavator, where A is the side of the traveling body and B is the side of the rotating body. 1 is a traveling motor that drives the traveling body; 2 is a hydraulic cylinder that is an actuator for an earth removal plate provided as an attachment; 3 is a main pump that is a hydraulic power source for the traveling motor 1 and the hydraulic cylinder 2; 4 and 5 are these pumps. It is a control valve, and the secondary side circuit 7 of the control valves 4 and 5,
8, 9, and 10 are connected to the traveling motor 1 and hydraulic pressure via oil passages formed in a center joint 11 provided between the traveling body and the revolving body, respectively, and through traveling body side circuits 12, 13, and 14, 15. Connected to cylinder 2. 16 is an auxiliary pump;
The discharge side circuit 17 is connected to the brake cylinder 20 via an oil passage provided in the center joint 11, a traveling body side circuit 18, and a brake switching valve 19, and when the control valve 4 is in the left or right position, the circuit is connected to the brake cylinder 20. 12 or 13 is applied to the brake switching valve 19 via the shuttle valve 21.
The valve 19 is switched to contract the brake cylinder 20 and release the brake. One running motor 1 is provided on the left and one on the right, and one control valve 4 is also provided on the left and right, but only one of them is shown in the figure. Further, 19' indicates a brake switching valve for the brake for the traveling motor on the side not shown.

Conventionally, the center joint 11 also requires a dedicated oil passage for the actuator of the device added as an attachment, so the center joint, which has oil passages for the travel motor 1 and the brake switching valve 19, is used as a hydraulic cylinder. It was necessary to replace it with one that also had a second oil passage, which had the drawbacks of significantly increasing the price and requiring time and effort to replace it.

In addition, as another conventional technology, an earth drill is equipped with an oil passage that serves both the travel motor and the hydraulic cylinder for track widening, and when the operator operates a travel switching valve provided on the traveling body side, the travel motor and the hydraulic cylinder are connected. However, the operator has to leave the driver's seat and operate the travel selector valve each time the driver switches between travel and track widening, resulting in poor work efficiency. .

In view of the above-mentioned drawbacks, the present invention provides a running circuit for a working machine having a structure that allows an attachment having an actuator to be easily and cost-effectively added to the running body side and improves workability. With the goal.

In order to achieve this objective, the present invention makes the oil passage for the travel motor in the center joint also serve as the actuator, and includes a travel switching valve in the circuit on the traveling body side of the oil passage to switch the oil passage between the travel motor and the actuator. In addition, by operating a switching valve provided on the revolving body side, the oil passages of the traveling motor and the actuator can be switched by the traveling switching valve.

An embodiment of the present invention will be described below with reference to FIG. In FIG. 2, the same reference numerals as in FIG. 1 indicate components having the same functions. In the present invention, for example, the oil passage dedicated to the hydraulic cylinder 2 for driving the earth removal plate is not provided in the center joint, and the oil passage for the travel motor 1 is also used as the center joint 11'. Moreover, the control valve 4 for the travel motor also serves as a control valve for the hydraulic cylinder 2 without adding a new one. In the oil passage on the side of the traveling body A, there is a travel switching valve 22 that switches the oil passage to the travel motor 1 and the actuator 2.
An operating rod 22 of the travel switching valve 22 is provided.
a is connected to a rod 24a of a spring cylinder 24 to which pressure oil is supplied via a circuit 23 from the brake oil passage 18 of the center joint 11';
When there is no oil pressure in the hydraulic cylinder 8, the travel switching valve 22 is switched to the hydraulic cylinder 2 side by the force of the spring 24b, and when there is oil pressure, the travel switching valve 22 is switched to the travel motor 1 side (as shown). In addition, the discharge side circuit 17 of the auxiliary pump 16 includes a supply of pressure oil to the circuit 18,
A switching valve 25 is inserted to control shearing. Although the switching valve 25 is of an electromagnetic type that is switched by turning the switch 26 on and off, it may be of any other type as long as it can be switched by an operator's operation.

In this configuration, when the switching valve 25 is in the right position as shown, the circuits 17 and 18 are in communication, so the spring cylinder 24 is connected to the auxiliary pump 1.
6 is supplied, the switching valve 22 is in the left position as shown in the figure, and the circuit 12, 1 to the traveling motor 1 is
3 communicates with the primary side circuits 27 and 28 of the switching valve 22. Therefore, when the control valve 4 is placed in the left or right position, the pressure oil discharged from the main pump 3 is supplied to the travel motor 1 from the circuit 12 or 13, and the brake switching valve 19 is switched, causing the brake cylinder 20 to contract. Since the brake is then released, the travel motor 1 is driven in the forward or reverse direction.

On the other hand, switch 26 is turned on and switching valve 2
5 to the left position, the discharge pressure oil from the auxiliary pump 16 to the circuit 18 is immediately cut off, and the circuit 18 is communicated with the tank 29 via the switching valve 25, so that the hydraulic pressure in the circuit 18 disappears and the spring cylinder 2
4 is the travel switching valve 22 by the force of the spring 24b.
is switched to the right position, this time the oil path to the travel motor 1 is briefly cut off, the oil path to the hydraulic cylinder 2 is communicated, and the hydraulic cylinder 2 is operated by operating the control valve 4 in the same manner as above. becomes possible.

In the example, a case was explained in which a soil removal plate was attached as an attachment to a hydraulic excavator, but the hydraulic excavator was modified and used as an automobile dismantling machine, and a press arm for pressing an automobile onto a traveling body and its driving cylinder were used. When setting up
The present invention can also be applied to other cases, and can also be applied when the actuator is a hydraulic motor rather than a hydraulic cylinder.

As described above, according to the present invention, when an attachment having an actuator is added to a traveling body, there is no need to newly provide an oil passage to the center joint, and it is also necessary to add a control valve and a circuit on the rotating body side. Since there is no need for additional functions and functions can be added by simply adding a switching valve or the like, the purpose can be achieved easily and at low cost. Further, according to the present invention, the operator can switch the travel switching valve while sitting in the driver's seat, resulting in good work efficiency.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic circuit diagram showing a running circuit of a conventional hydraulic excavator, and FIG. 2 is a hydraulic circuit diagram showing a running circuit of a hydraulic excavator according to an embodiment of the present invention. 1...Travel motor, 2...Hydraulic cylinder, 3...
...Main pump, 4...Control valve, 11'
... Center joint, 16 ... Auxiliary pump,
19...brake switching valve, 20...brake cylinder, 22...travel switching valve.

Claims (1)

[Scope of utility model registration request] A main pump and an auxiliary pump are installed on the revolving body,
In the running circuit of a working machine, in which a running motor, a brake cylinder, and a brake switching valve for releasing the brake during running are installed on the running body, and an actuator for driving an attachment is installed on the running body, on the discharge side of the main pump. The traveling motor and the actuator share a control valve provided therein and an oil passage provided in the center joint, and the oil passage on the traveling body connected to the dual-purpose oil passage is connected to the traveling motor. and a traveling switching valve that switches an oil path to the actuator, and the traveling switching valve controls the hydraulic pressure of the traveling body side portion of the oil path that extends from the auxiliary pump to the primary side of the brake switching valve via the center joint. The secondary side of the switching valve is switched to the traveling motor side and the actuator side, respectively, depending on the presence or absence of the switching valve. A running circuit for a working machine characterized by being provided with a switching valve for supplying and cutting off oil to a brake switching valve side oil passage.