JPS6338296Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic circuit for a shovel loader, and more particularly to an improvement in the hydraulic circuit for a shovel loader equipped with a rear attachment.

Conventionally, in the hydraulic circuit of a shovel loader equipped with a rear attachment (hereinafter referred to as buckethoe) as shown in Fig. 1, the bucket control valve 8 is a carry-over type, as shown in Fig. 4. The hydraulic oil that has passed through the valve 8 is supplied to the control valve 9 for the backhoe, and since the hydraulic oil always flows to the control valve 9 for the backhoe, the hydraulic piping resistance is extremely large and constantly affects the engine. Particularly when the temperature is low, the engine performance cannot be achieved as set.

In addition, in the embodiment illustrated in FIG. 5, a selector valve 16 is provided near the outlet of the pump 7, and by operating the selector valve 16, either the bucket control valve 8 or the bucket control valve 9 is activated. Hydraulic pressure is now being supplied. In this case, the cost of the selector valve 16 is high, and if either the bucket control valve 8 or the bucket control valve 9 is made operable, the other control valve will not operate. Therefore, when working with the Batshoe 3, the bucket 2 and outriggers 3a are placed on the ground, and the front and rear wheels are lifted off the ground. However, when digging a long trench, for example, the operator remains seated in the driver's seat of the Batshoe 3. The work involves raising the bucket 2 and outriggers 3a, touching the front and rear wheels to the ground, and using the power of the bucket hoe 3 to move the machine forward. It had the disadvantage that it was not possible to do so (it required a lever to be interlocked with the lever).

The purpose of this invention is to solve the above-mentioned drawbacks.The purpose of this invention is to connect one end of the drain pipe to the pipe connecting the bucket control valve and the bucket control valve, and install an on-off valve in the pipe. An object of the present invention is to provide a hydraulic circuit which has low piping resistance during bucket work, and which can operate a bucket control valve during bucket work. The present invention will be explained in detail below based on the illustrated embodiments.

In FIG. 1, 1 is a shovel loader equipped with a bucket 2, a bucket 3, and an outrigger 3a.As shown in FIG. A pump 7 driven by a prime mover 6 is interposed in the pump 5 . The pipe 5 passing through the pump 7 is communicated with a control valve 9 for a bucket hoe via a control valve 8 for a bucket. The control valves 8, 9 have return lines 10, 11 to the hydraulic oil tank 4, respectively. One end of a drain pipe 13 is connected in the middle of the pipe 5 connecting the bucket control valve 8 and the bucket hoe control valve 9.
There is an on-off valve 14 in the middle of the drain pipe 1.
The other end of 3 is connected to a hydraulic oil tank 4.

The present invention has the above-mentioned structure, and its operation will be explained. First, when operating the bucket control valve 8 to operate the bucket 2, the bucket control valve 8 is opened by opening the on-off valve 14. Since the discharged hydraulic oil returns to the hydraulic oil tank 4 through the return pipe 10 and the drain pipe 13, the piping resistance of the hydraulic oil flowing from the backhoe control valve 9 to the backhoe 3 side is significantly reduced.

Next, when operating the bucket hoe control valve 9 to operate the bucket hoe 3, the on-off valve 14 is closed and the bucket control valve 8 is operated.
All of the hydraulic oil that exits is sent to the control valve 9 for the backhoe. Therefore, Batsukuho 3
If you remain seated in the driver's seat of the Buckhoe 3 and attach the control lever (not shown) that interlocks with the control valve lever for the bucket within arm's reach of the driver's seat of the Buckhoe 3 when it is ready to operate, The up and down operations of the outrigger 3a and the bucket 2 can be performed efficiently.

Note that it is also possible to integrate the bucket control valve 8 and the on-off valve 14 into one body.

Next, as another embodiment, as shown in FIG. 3, the on-off valve 14 is replaced with a solenoid valve 15, and a limit switch (not shown) is installed under the driver's seat (not shown) of the machine. When the driver sits on the driver's seat of the machine, the limit switch is turned on, thereby operating the solenoid valve 15 and opening the circuit within the solenoid valve 15. Therefore, when operating the bucket 2, the hydraulic oil that has exited the bucket control valve 8 returns to the hydraulic oil tank 4 through the return pipe 10 and the pipe 13. The piping resistance of the hydraulic oil flowing from 8 to the bucket 2 side is significantly reduced. In addition, when operating the control valve 9 for the bucket hoe to operate the bucket hoe 3, the driver leaves the driver's seat for the bucket and sits on the seat for the bucket. The limit switch turns OFF at the moment
This closes the solenoid valve 15, and all of the hydraulic fluid that has exited the bucket control valve 8 is sent to the backhoe control valve 9. Therefore, when the driver sits in or leaves the bucket driver's seat, the solenoid valve 1
5 can be opened and closed automatically.

As described above, according to the present invention, a drain pipe that communicates with the hydraulic oil tank is connected in the middle of the pipe that communicates the bucket control valve and the bucket hoe control valve, and a selector valve is connected in the middle of the drain pipe. By providing an inexpensive and simple on-off valve, it is possible to operate the control valve for buckets even when the control valve for buckets can be operated, and the hydraulic piping resistance when the control valve for buckets can be operated is reduced. Furthermore, it has remarkable effects such as being able to automate the opening and closing of circuits to reduce hydraulic piping resistance.

[Brief explanation of the drawing]

FIG. 1 is a side view of a shovel loader, FIG. 2 is a hydraulic circuit diagram, FIG. 3 is a hydraulic circuit diagram showing another embodiment, and FIGS. 4 and 5 are conventional hydraulic circuit diagrams. 1...Shovel loader, 2...Bucket, 3...
...Buckhoe, 4...Hydraulic oil tank, 5...Pipeline, 8...Bucket control valve, 9...
...Control valve for backhoe, 13...Drain pipe, 14...Opening/closing valve.

Claims (1)

[Scope of utility model registration request] A bucket seat mounted on the front of the vehicle body, a hydraulic pump driven by a prime mover mounted inside the vehicle body, a main seat located on the engine hood in the center of the vehicle body, and a bucket seat located near the main seat. A bucket control valve for controlling the vehicle body, a rear attachment device attached to the rear of the vehicle body, an auxiliary seat attached to the rear attachment device, and a rear attachment control valve disposed near the auxiliary seat. , the pressure oil in the hydraulic oil tank discharged from the hydraulic pump is supplied to the inlet port of the control valve for the bucket, and the control valve for the rear attachment is supplied from the outlet port of the control valve for the bucket through a communication pipe. In a shovel loader, the drain pipe has one end connected to the communication pipe line and the other end connected to the hydraulic oil tank in a shovel loader having a hydraulic circuit for supplying the oil to the inlet port of the control valve and returning the hydraulic oil from the outlet port of the control valve into the hydraulic oil tank. 1. A hydraulic circuit for a shovel loader, characterized in that a drain pipe is provided, and an on-off valve for controlling opening and closing of the drain pipe is installed in the drain pipe.