JPS625891Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a return valve mechanism for returning a piston moving up and down in a cylinder, such as in an air nailer.

FIG. 1 shows a conventional pneumatic nailer with a return valve mechanism for returning the piston. To briefly explain this operation, the compressed air accumulated in the air reservoir chamber is moved through the valve chamber 13 and the valve hole 15 via the communication passage 10 by opening the main valve 6 as shown in the figure. It flows into the lower valve chamber 12 via the air. At the same time, the drive piston 3 descends to eject a driving tool (not shown). On the other hand, when the main valve 6 is closed (not shown) and the lower part of the main valve 6 is opened to the atmosphere in order to return the drive piston 3 to its original position, the compressed air that has flowed into the valve chamber 13 passes through the communication passage 10 and is released to the atmosphere. . Therefore, a pressure difference is generated between the upper surface and the lower surface of the piston valve 11, so that the piston valve 11 is lowered. As a result, the valve 19 is lowered, so that compressed air rapidly flows from the unillustrated air reservoir chamber through the passage 21 and the communication passage 10 to the lower surface of the drive piston 3, and the drive piston 3 returns to its original position. On the other hand, the compressed air flowing into the lower valve chamber 12 passes through the small-diameter exhaust passage 18 and is discharged to the atmosphere, so that the pressure within the lower valve chamber 12 is atmospheric pressure when the next driving operation is performed.

This conventional return valve structure generally uses compressed air compressed by a compressor, so condensate is mixed in with the compressed air, and lubricating oil is also supplied to reduce the sliding resistance of each part. Therefore, during long-term use, this drain and lubricating oil accumulate in the lower valve chamber 12, and the lower valve chamber 12
Since the capacity of the piston valve 11 is reduced, there is a drawback that the piston valve 11 does not operate completely.

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to ensure reliable operation of the return valve mechanism of this type of driving machine.

The present invention focuses on the fact that drain and lubricating oil accumulate in the lower part of the valve chamber due to gravity, and the lower valve chamber is positioned so that it is normally at the bottom when using a driving machine. A passage communicating with the atmosphere is provided at the bottom of the valve chamber, and the compressed air flowing into the lower valve chamber is devised to discharge drain and lubricating oil every time or when a certain amount is exceeded.

FIG. 2 shows an example of a driving machine according to the present invention that uses compressed air and is equipped with a return valve mechanism for returning the drive piston. Main valve 6 for driving operation
When the valve is in the open state as shown in the figure, that is, the upper ball valve is raised and the lower O-ring is in the closed state,
Compressed air accumulated in a compressed air storage chamber (not shown) flows through the lower part of the ball valve in the direction of the arrow.
0 into the valve chamber 13.

Furthermore, it also flows into the lower valve chamber 12 formed at the lower end of the valve chamber 13 through the valve hole 15 . At the same time, the drive valve (not shown) is operated by the main valve 6 to open the upper part of the cylinder 2, so the drive piston 3 rapidly descends and drives the tool to be driven (not shown) into the driving machine. . After the tool to be driven is driven,
When the main valve 6 is closed contrary to the illustration, that is, the upper ball valve is lowered to prevent compressed air from flowing into the valve chamber 13, and the lower O-ring is opened, the air is accumulated in the valve chamber 13. Since the compressed air is released into the atmosphere, a pressure difference is created between the lower surface and the upper surface of the piston valve 11, and the piston valve 11 moves upward in the figure. When the piston valve 11 moves upward, the valve 19 is pushed up, and compressed air suddenly flows into the lower part of the driving piston 3 through the passage 21 communicating with the compressed air reservoir, the valve 19 section, and the communication passage 10, and the driving piston Return 3 to its original position. On the other hand, the compressed air accumulated in the lower valve chamber 12 located below the valve chamber 13 is gradually released to the atmosphere through the exhaust passage 18 and the passage 23 communicating with the atmosphere, and the drive piston 13 returns to its original position. The passage areas of the exhaust passage 18 and the passage 23 are set so that the pressure in the lower valve chamber 12 is approximately close to atmospheric pressure when the pressure returns to . Therefore, when the pressure inside the lower valve chamber 12 reaches approximately atmospheric pressure, the piston valve 11 is pushed down as shown in the figure due to the force of the compressed air acting on the upper surface of the valve 19 and the force of the spring 20. The valve 19 is closed and compressed air flowing into the lower part of the drive piston 3 is cut off. Further, the compressed air flowing into the lower part of the drive piston is discharged to the atmosphere as shown in the figure so as not to interfere with the next driving operation. This completes one cycle of the driving machine.

With this configuration, the lower valve chamber 12 of the present invention has a valve chamber 13.
It is located below the tank, and is arranged so that impurities such as drain and oil can accumulate at the bottom. Also, a passage 2 communicating with the atmosphere for discharging these impurities.
3 is provided at the bottom of the lower valve chamber 12 to discharge impurities every time the driving operation is directed downward.

In the present invention, the passage 23 is provided at the bottom in relation to the capacity of the lower valve chamber 12. However, if the capacity of the lower valve chamber 12 is large, the passage 23 is located on the lower side wall of the lower valve chamber 12, and the piston valve 11 A similar effect can be obtained by allowing the accumulation of impurities to the extent that no malfunction occurs in the operation of the device.

As described above, according to the present invention, the lower valve chamber is provided at the lower end of the return valve mechanism, and the exhaust passage communicating with the atmosphere is provided at the bottom of the lower valve chamber, making it possible to drain drain and lubricating oil. Even if the driving machine is used for a long time, the return operation of the piston valve will not deteriorate due to insufficient capacity of the lower valve chamber, and the drive piston can always be returned normally.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of a conventional driving machine with a return valve, and FIG. 2 is a sectional view showing an embodiment of the driving machine with a return valve according to the present invention. In the figure, 2 is a cylinder, 3 is a driving piston, 6 is a main valve, 10 is a communication passage, 11 is a piston valve, 12 is a lower valve chamber, 13 is a valve chamber, and 23 is a passage.

Claims (1)

[Claims for Utility Model Registration] A main valve that controls opening/closing of an air passage connecting the upper part of the cylinder that slidably houses the drive piston and the pressure supply source, and a communication between the pressure supply source and the lower end of the cylinder. A cylindrical valve chamber provided in the middle of the passage,
A return valve mechanism for a driving machine including a piston valve that is slidably fitted into the valve chamber and opens and closes the communication passage, the lower valve being partitioned and partitioned by the piston valve. A chamber is arranged and formed at the lower end of the valve chamber, and a passage communicating with the atmosphere is bored at the bottom of the lower valve chamber so that compressed air and impurities such as drain from the lower valve chamber can be appropriately discharged. Return valve mechanism for driving machine.