JPS6235971Y2 - - Google Patents

Description

[Detailed description of the invention] This invention connects the pump and motor with a pair of main passages to form a closed circuit, and separates the hydraulic power source circuit including the pump from the actuator circuit including the motor. The present invention relates to a valve structure used in a circuit that can replace the hydraulic power source circuit.

Commonly thought of hydraulic circuits of this type are shown in Figures 1A and 1B.

That is, FIG. 1A shows the main circuit, and FIG. Main passage 3,
4 to form a closed circuit.

A shuttle valve S is provided between the main passages 3 and 4.
At the same time, a flushing relief valve R is connected to this shuttle valve S.

However, if the main passage 3 is now on the pressure oil supply side and the main passage 4 is on the return side, the shuttle valve S is switched to the left position as shown. Shuttle valve S
When the pump is switched to the left-hand position, the return oil from the main passage 4 returns to the main pump 1, and part of it reaches the flushing relief valve R via the shuttle valve S.

Therefore, the circuit pressure on the return side is the same as that of the relief valve R.
When the pressure exceeds the set pressure, the relief valve R opens and some of the returned oil is returned to the tank 5 for flushing.

Reference numeral 6 in the figure is an auxiliary pump, which removes the insufficient oil when the flushing oil is removed from the closed circuit.
It supplies the closed circuit. In other words, the oil discharged from this auxiliary pump 6 is checked by the check valve 7 or 8.
It is supplied to the low-pressure side of the closed circuit, that is, the return side, via the. The supply pressure by this auxiliary pump 6 is controlled by a relief valve r.

Also, alternative hydraulic power source circuit B shown in Figure 1B
is equipped with a main pump 9 and an auxiliary pump 10,
Main passages 11 and 12 are connected to the main pump 9, and these pumps 9 and 10 perform the same function as the pumps 1 and 6 in the main circuit.

However, if the hydraulic power source circuit A in the main circuit breaks down, the connecting portions X and Y of the main passages 3 and 4 are disconnected, and the hydraulic power source circuit A is connected to the motor 2, the shuttle valve S, and the flushing relief valve R. separated from the actuator circuit containing the Then, the connecting portions M, N of the main passages 12, 13 in the alternative hydraulic power source circuit B are connected to the connecting portions X, Y. In this way, the motor 2 can be continuously driven by the main pump 9 of the circuit B.

However, in this case, since the actuator circuit remains the same, the circuit system of the shuttle valve S→flushing relief valve R→tank 5 is disconnected from the hydraulic pressure source circuit B.

Therefore, the flushing oil that has passed through the relief valve R returns to the tank 5 side and does not return to the tank on the alternative hydraulic power source circuit B side. Therefore, the amount of oil on the circuit B side gradually decreases, and eventually the function as a hydraulic power source stops.

Conventionally, the shuttle valve S was configured as shown in FIG. 3, and when the alternative circuit B was connected, the function of the shuttle valve S was stopped to prevent the flushing oil from returning to the tank 5. was.

In other words, this shuttle valve S has its spool 14
Both ends thereof face into pressure chambers 15, 16, and these pressure chambers 15, 16 are connected to the main passages 3, 4 via ports 17, 18.

And now one pressure chamber, for example pressure chamber 15
When high pressure oil from the pressure oil supply side flows into spool 1,
4 is shifted to the right side in the drawing, and the port 18 communicating with the main passage on the return side is communicated with the flushing relief valve R.

Stoppers 19 and 20 are engaged with the shuttle valve S from the outside at both ends thereof. The stoppers 19 and 20 are rotated to bring their inner ends into contact with both ends of the spool 14, thereby preventing the spool 14 from moving.

If the spool 14 is regulated by the stoppers 19 and 20, the oil in the alternative hydraulic power source circuit B will not return to the tank 5.

However, in the above-mentioned conventional shuttle valve S, since two stoppers 19 and 20 must be provided, the number of parts increases accordingly, and the structure becomes complicated, resulting in high manufacturing costs.

Furthermore, not only is the manufacturing cost high, but the operation of the two stoppers 19, 20 is also troublesome.

This idea is designed to hold down the poppet of the flushing relief valve connected to the shuttle valve.
This eliminates the above-mentioned conventional drawbacks. That is, by pressing the poppet of the relief valve, only one holding mechanism is required, and moreover, it is only necessary to operate one holding mechanism, thereby solving the above-mentioned drawbacks of the conventional valve.

The embodiment shown in FIG. 2 will be described below.

The valve body 21 in this embodiment is provided with a shuttle valve S and a flushing relief valve R.

The shuttle valve S has both ends of its spool 22 facing into the pressure chambers 23 and 24, and springs 25 and 26 are interposed in the pressure chambers 23 and 24, so that the spool 22 is normally held at the neutral position shown in the figure. We have a relationship where

The valve body 21 includes the main passages 3 and 4.
Ports 27 and 28 are formed which communicate with the pressure chambers 23 and 24 through communication holes 29 and 30, respectively.

Further, when the spool 22 is held at the neutral position, communication between the ports 27 and 28 and the relief passage 31 reaching the flushing relief valve R is cut off.

The relief valve R includes a poppet 32, a pressing member 33, and an adjusting screw 34.

The poppet 32 is located within the relief passage 31, and is normally maintained in the closed state shown in the figure by the action of a spring 35 interposed between the poppet 32 and the presser member 33. That is, the flange portion 36 of the poppet 32
is brought into pressure contact with the opening end surface of the relief passage 31, so as to close the small hole 37 of the poppet 32.

Further, the upper end of the presser member 33 is connected to the adjusting screw 3.
4, and is moved up and down by turning an adjustment screw 34 that protrudes outward from the valve body 21.

Thus, when the hydraulic power source circuit A is operating normally, the pressing member 33 is kept separated from the poppet 32. Push the holding member 33 into the poppet 32.
If the flushing relief valve R is kept separated from the main body, the flushing relief valve R will function normally.

For example, if pressure oil from the main passage 3 on the supply side flows into the port 27, the pressure oil enters the pressure chamber 23 via the communication hole 29, and the spool 22
is moved against the spring 26. When the spool 22 moves in this way, the port 28 that communicates with the main passage 4 on the return side is connected to the relief passage 31.
It will be communicated with. Therefore, when the circuit pressure on the main passage 4 side exceeds the set pressure of the relief valve R, the poppet 32 moves upward against the spring 35 and opens the small hole 37. That is, the oil in the closed circuit is returned to the tank 5 via the relief valve R to perform flushing.

Furthermore, when connecting the alternative hydraulic power source circuit B, if the adjustment screw 34 is turned to bring the holding member 33 into contact with the poppet 32, the relief valve R will not open, and the oil will return to the tank 5. No more getting tired. As is clear from this,
The holding member 33 and the adjusting screw 34 constitute the poppet holding mechanism of this invention.

While this alternative hydraulic power source circuit B is connected, the hydraulic power source circuit A of the main circuit is repaired and then reconnected.

As is clear from the above explanation, according to the valve structure of this invention, after the replacement work of the hydraulic power source circuit is completed, the holding mechanism of the flushing relief valve can be operated to kill the relief function of the relief valve. I can do it. In other words, in the conventional case, it was necessary to operate two holding mechanisms on both sides of the shuttle valve, but with this invention, by operating only the holding mechanism of the flushing relief valve, the desired purpose can be achieved. can be achieved.

Therefore, this invention not only reduces the number of parts and reduces the manufacturing cost, but also simplifies the operation since only one operation is required.

[Brief explanation of the drawing]

Figure 1 is a general circuit diagram using the valve structure of this invention, Figure 1A is the main circuit diagram;
Figure 2 is a circuit diagram of an alternative hydraulic power source, Figure 2 is a cross-sectional view showing one embodiment of this invention, and Figure 3 is a conventional cross-sectional view. 1... Main pump, 2... Motor, 3, 4...
...Main passage, S...Shuttle valve, R...Flushing relief valve, A...Hydraulic pressure source circuit, B...Alternative hydraulic power source circuit, 32...Poppet, 33 and 3
4...The holding member and adjustment screw that constitute the poppet holding mechanism.

Claims (1)

[Scope of utility model registration request] The pump and motor are connected by a pair of main passages to form a closed circuit, while a shuttle valve is connected between the two main passages, and a flushing relief valve is connected to the shuttle valve, and furthermore,
In a circuit in which the hydraulic power source circuit including the pump and the actuator circuit including the motor, shuttle valve, and flushing relief valve are separated, and the hydraulic power source circuit can be replaced, the flushing relief valve has its poppet. stop the operation of
The valve structure of the circuit makes it possible to replace the hydraulic power source circuit with a poppet holding mechanism that maintains the valve in a closed state.