JPH0115906Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a free-valve single-acting two-stage reciprocating vacuum pump.

A conventional single-acting two-stage reciprocating vacuum pump, as shown in Fig. 3 and described in Japanese Utility Model Publication No. 30-15974, uses a piston 1 in a cylinder to supply both chambers 2 and 3 on the left and right sides. In a vacuum pump equipped with several suction valves 4, 4' and several discharge valves 5, 5', which are divided into chambers 2 and 3 and communicated with each other through communication pipes 6 and 7, the suction side and the discharge side are separated. One blocking valve 8A and 8B are provided in the communicating pipes 6 and 7, respectively, and the communicating pipe further connects the right side of the blocking valve 8A and the left side of the blocking valve 8B, and has a blocking valve 8C in the middle. There was one with the number 9.

This pump operates by opening the blocking valves 8A and 8B and closing the blocking valve 8C (operates as a double-acting 1-stage vacuum pump), then closes the blocking valves 8A and 8B, and closes the blocking valve 8C. When it is opened and operated, it operates as a single-acting, two-stage vacuum pump, and because the communication pipe is long and the cross-sectional area of the pipe is narrow due to the many blocking valves, the gas passing through is Due to the increase in fluid resistance and the time lag between the suction process after the discharge process, the single-acting, two-stage reciprocating vacuum pump cannot function satisfactorily. This increased the size of the pump as a whole, and there were many sealing points, and the higher the vacuum, the greater the risk of leakage.

This invention eliminates the need to open and close a stop valve, or to worry about leaks from piping or fittings, and eliminates the need for a stop valve or long, thin pipes. To provide a single-acting, two-stage reciprocating vacuum pump that automatically performs two stages of work during the pulling stroke, has a simple structure, can be designed in a compact size, and can significantly reduce manufacturing costs. That is, the present invention is based on FIGS. 1, 2, 4, and 5.
As shown in the figure, a free valve type upper suction valve 11 and a free valve type upper discharge valve 12 are provided in the upper part of the cylinder 10, and a free valve type lower suction valve 13 and a free valve type lower discharge valve 14 are provided in the lower part. , the upper discharge valve 12 and the lower suction valve 13 are surrounded by a side wall 151 that covers and surrounds the outer wall 101 of the cylinder 10 with a gap so that the passage cross-sectional area is wide with respect to the outer diameter of the piston 20 and the distance is the shortest. The formed gas passage 15 communicates with the upper suction valve 11 and lower discharge valve 1 during the pulling stroke.
4 is opened, and the upper discharge valve 12 and lower suction valve 13 are opened.
is closed, and the upper discharge valve 12 and lower suction valve 13 are opened during the pushing stroke, while the upper suction valve 11 and lower discharge valve 1 are closed.
4 is closed.

An embodiment of the present invention will be described based on FIGS. 1, 2, and 4.

10 is a cylinder, 11 is a free valve type upper suction valve provided at the top of the cylinder 10, and 12 is a cylinder 10.
13 is a free-valve type upper discharge valve provided at the top of the cylinder 10; 1 is a free-valve type lower suction valve provided at the bottom of the cylinder 10;
4 is a free-valve type lower discharge valve provided at the lower part of the cylinder 10; 15 is a gas passage formed by a side wall 151 that covers and surrounds the outer wall 101 of the cylinder 10 with a gap between the upper discharge valve 12 and the lower suction valve 13; 20 is a piston that has a wide passage cross-sectional area relative to the outer diameter of the piston 20 and communicates with the shortest distance.
Note that 16 is cooling water, and 17 is a cooling water sleeve. In addition, FIG. 5 shows the cooling water cannula 17 in the above embodiment.
This figure shows another embodiment in which an air cooling fin 18 is attached instead of.

As shown in FIG. 2, the present invention is designed so that the upper suction valve 11 opens during the retraction stroke and the vacuum tank (not shown) is opened.
The upper discharge valve 12 and the lower suction valve 13 are closed, and the lower discharge valve 14 is opened to discharge the gas in the cylinder 10 below the piston 20 to the outside, as shown in FIG. , open the upper discharge valve 12, and open the upper suction valve 11 and lower discharge valve 14.
is closed, the gas in the cylinder 10 above the piston 20 is pushed out to the gas passage 15, and the lower suction valve 13 is opened to suck the gas into the cylinder 10 below the piston 20. That is, 1 cylinder,
The pushing stroke of one piston has one stage of work, and the pulling stroke has two stages of work.

Therefore, in the present invention, when the piston 20 reaches the top dead center during the pushing stroke, the residual gas between the upper part of the cylinder 10 and the upper part of the piston 20 can be removed from the upper discharge valve 12 through the lower suction valve 13. The residual gas pressure at the top of the piston is considerably lower than the atmospheric pressure, and when the piston 20 moves from the push stroke to the pull stroke, the residual gas pressure becomes even more negative, causing the upper suction valve 11 to move quickly. When it came to opening,
The gas can be sucked up to even higher vacuum levels. Further, the gas passage 15 that communicates the upper discharge valve 12 and the lower suction valve 13 is used as a gas passage during the pushing stroke of the piston 20, and since it utilizes the outer wall of the cylinder 10, there is no sealing point. In addition to minimizing the risk of gas leakage, the cross-sectional area of the passage is relatively wide relative to the outer diameter of the piston, and communication can be achieved over the shortest distance, reducing the pulsating pressure associated with gas discharge and suction in the gas passage. By making maximum use of this, the free-valve discharge and suction valves are made easy to open, allowing for an immediate transition from the discharge stroke to the suction stroke.

According to this invention, as a vacuum pump that performs two stages with one piston, it does not require complicated valves, piping, or seals, has a simple and compact structure, can be operated automatically, and is manufactured at low cost. It has certain advantages.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams of the present invention, Figure 3 is an explanatory diagram of a conventional example, Figure 4 is a cross-sectional view of main parts showing an embodiment of the present invention, and Figure 5 is an explanatory diagram of the present invention. FIG. 6 is a cross-sectional view of main parts showing another embodiment of the invention. 10... Cylinder, 101... Outer wall of cylinder, 11... Upper suction valve, 12... Upper discharge valve,
13...Lower suction valve, 14...Lower discharge valve, 15
...Gas passage, 151...Side wall, 20...Piston.

Claims (1)

[Scope of utility model registration request] A free valve type upper suction valve 11 is installed at the top of the cylinder 10.
and a free valve type upper discharge valve 12, and a free valve type lower suction valve 13 and a free valve type lower discharge valve 14 are provided at the lower part, and the upper discharge valve 12 and the lower suction valve 13 are provided.
The cylinder 1 has a wide passage cross-sectional area with respect to the outer diameter of the piston 20 and has the shortest distance.
The outer wall 101 of 0 is communicated with a gas passage 15 formed by a side wall 151 covered and surrounded with a gap, and in the pulling stroke, the upper suction valve 11 and the lower discharge valve 14 are opened, and the upper discharge valve 12 and the lower suction valve 13 are closed. A single-acting two-stage reciprocating vacuum pump characterized in that an upper discharge valve 12 and a lower suction valve 13 are opened and an upper suction valve 11 and a lower discharge valve 14 are closed during a pushing stroke.