JPH086688B2 - Multi-stage reciprocating vacuum pump - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a completely oil-free, horizontally opposed, multi-stage reciprocating vacuum pump.

2. Description of the Related Art A conventional reciprocating vacuum pump has an oil supply type inside a crankcase, so that it is necessary to provide a distance piece (spacer) chamber adjacently and an oil stopper. ,
Also, in the multi-stage reciprocating vacuum pump, it is necessary to provide a long gas passage communicating with the intake / exhaust valve provided in the cylinder cover on the outer wall of the cylinder. There was a limit.

Further, in the conventional reciprocating vacuum pump, especially in the opposed piston type multi-stage reciprocating vacuum pump, vibration is severe due to inertial force and imbalance of piston reciprocating motion, which requires structural strength and is difficult to reduce the weight. .

Further, since the conventional reciprocating vacuum pump is of the oil supply type as described above, there is a risk that oil will be mixed in the vacuum exhaust system passage, and it is used as a semiconductor manufacturing device or other vacuum pump requiring a clean high vacuum. It was difficult.

It is an object of the present invention to provide a multi-stage reciprocating vacuum pump which can be made smaller and lighter than the conventional type, and which can reduce vibration extremely. Another object of the present invention is to
It is to provide a multistage reciprocating vacuum pump capable of obtaining a clean high vacuum.

Further objects of the present invention will be made clear by the following detailed description.

Means for Solving the Problems In order to achieve the above object, a multistage reciprocating vacuum pump according to the present invention is configured such that all lubricating parts of a crank motion part and a piston motion part are oil-free, and two pistons are horizontally opposed. And a multi-stage reciprocating vacuum pump in which the piston load acting lines are formed in a straight line, wherein two cylinders are provided by an upper cylinder cover provided with a suction valve and a lower cylinder cover provided with a discharge valve. In addition, each of the two pistons is provided with a check valve that allows the gas to pass through the pistons in the pushing stroke. The suction valve and the discharge valve are closed together in the push stroke and opened together in the pull stroke, and the lower cylinder cover has a piston rod in which one end of the bellows is attached to the lower cylinder cover and the other end is attached to the crosshead. Provide a shaft seal device.

In the present invention, the crank motion part is a crosshead,
Cross-head guide, connectin rod, cross-head pin, crank shaft, crank pin, crank shaft bearing, crank shaft shaft seal device, crank case, etc. are referred to, and the lubrication part is the cross head guide bush, cross head pin. There are bushes, crank pin metal, crank shaft bearings, crank shaft shaft sealing devices, etc.These oil-free lubrication products include solid lubricant-containing sintered bond metal, shield type bearings,
A grease filled seal is used.

Further, in the present invention, the piston moving part means a concept including a cylinder, a piston, a piston ring, a rider ring, a piston rod, a piston rod shaft sealing device, a cylinder cover, etc., and a lubricated portion thereof is a piston ring, a rider ring, a piston rod shaft. There is a sealing device, etc.
In lidaring, a resin containing tetrafluoroethylene resin as a main component is used.

Further, in the present invention, the cylinder is sealed by the upper cylinder cover and the lower cylinder cover so that the vacuum gas does not leak from the cylinder and the external gas does not enter the cylinder. For this sealing, a piston rod shaft sealing device including a bellows, one end of which is attached to the lower cylinder cover and the other end of which is attached to the crosshead, is provided in the piston rod penetrating portion of the lower cylinder cover.

Embodiment An embodiment of a multistage reciprocating vacuum pump of the present invention is shown in the drawings.

The vacuum pump of this example comprises a crank motion unit 1 and a piston motion unit 2.

The crank motion unit 1 includes a pair of cross heads 11 that reciprocate along a cross head guide 12 and a cross head pin.
A pair of connectin rods 14 rotatably connected to the crosshead 11 via 13 and a crankshaft 16 rotatably connected to the pair of connectin rods 14 via a crankpin 15; A pair of bearings 17 for supporting the crank shaft 16, a shaft sealing device 18 for shaft sealing the crank shaft 16, and a crank case 19 are provided.

The pair of cross heads 11 are each provided with an air circulation hole 110 penetrating a space 190 inside the crankcase and a space 260 in which a bellows type piston rod shaft sealing device 26 described later is provided. Also a crosshead guide 1
A water jacket 120 is provided on the outer periphery of 2.

A pair of crosshead guide bushings 121, a pair of crosshead pin bushings 131 and three crankpin metals 151 are made of sinter-bonded metal containing solid lubricant, and a pair of crankshaft shaft bearings 17 are shielded. Type bearings are used, and the crankshaft shaft sealing device is provided with a grease-sealed oil seal, which can be lubricated without oil.

The piston moving part 2 includes two laterally opposed reciprocating pistons 21 and 21 (the right and left pistons in FIG. 1 are both operated toward bottom dead center and both toward top dead center). A pair of cylinders 22, a pair of piston rods 23 each of which is connected to the piston 21 at one end and to the crosshead 11 at the other end, a pair of upper cylinder covers 24, and a pair of lower cylinders. A cover 25, a pair of piston rod shaft sealing devices 26, and a gas communication pipe (not shown) are provided.

To each piston 21, a piston ring 211 containing a tetrafluoroethylene resin as a main component is fitted via a tension ring 212, and a rider ring 213 containing a tetrafluoroethylene resin as a main component is fitted. Thus, they can be slid on the inner wall of the cylinder 22 without oil. Further, each of the pair of pistons 21 is provided with a check valve 214 that allows gas to pass through the pistons 21 in the pushing stroke.

Each cylinder 22 is sealed by an upper cylinder cover 24 and a lower cylinder cover 25, and a suction valve 241 is provided on the upper cylinder cover 24 at a position corresponding to the check valve 214 of the piston 21. , The lower cylinder cover 25,
A discharge valve 251 is provided at a position of the piston 21 corresponding to the check valve 214.

The check valve 214 and the discharge valve 251 have the same structure. As shown in FIG. 4, the check valve 214 (discharge valve 251) includes a valve plate 2141 (2511), a valve seat 2142 (2512), It consists of a valve guide 2143 (2513), a valve bolt 2144 (2514) and a valve nut 2145 (2515). The suction valve 241 is
As shown in FIG. 3, it comprises a valve plate 2411, a valve seat 2412, a valve guide 2413, a valve bolt 2414 and a valve nut 2415.

As shown in FIGS. 1 and 2, the piston rod shaft sealing device 26 comprises a bellows, one end of which is hermetically coupled to the lower cylinder cover 25, and the other end of which is hermetically coupled to the crosshead 11 via bolts 261. ing.

A gas communication pipe (not shown) communicates from the discharge port 250 of the lower cylinder cover 25 on the right side of FIG. 1 to the suction port 240 of the upper cylinder cover 24 on the left side of FIG.

Further, in this example, similar to the conventional opposed reciprocating vacuum pump, the weights of the reciprocating parts facing each other are equalized, and the unbalanced inertial force of the rotary motion part is balanced, and the crankshaft shaft 16 The cylinders 22 are horizontally opposed to each other so that the axes of the cylinders 22 are aligned with each other, and the crankshaft 16 has three crankpins 15 adjacent to each other with an angle of 180 degrees. The central crankpin 15 is connected to the crosshead 11 of the piston rod 23 on one side through the straight connectin rod 14, and the crankpins 15 and 15 on both sides of the central crankpin 15 are bifurcated. It is connected to the crosshead 11 of the other piston rod 23 through the shaped connectin rod 14.

Operation In the vacuum pump of the present invention, as the right piston 21 moves from the top dead center (the position shown in FIG. 1) to the bottom dead center (the position shown in FIG. 2) (drawing stroke) (at this time) , The left piston 21 also goes from top dead center to bottom dead center), gas is sucked from the suction port 240 of the right upper cylinder cover 24, enters the suction chamber 242, and then from the suction valve 241 to top dead. In the cylinder 22 on the point side, that is, because the check valve 214 of the piston 21 is closed while being sucked into the first space 221 formed between the upper cylinder cover 24 and the piston 21,
The gas in the second space 222 formed in the cylinder 22 on the bottom dead center side of the piston 21, that is, between the piston 21 and the lower cylinder cover 25 is discharged from the discharge valve 251 of the lower cylinder cover 25 to the discharge port 250. Through a gas communication pipe (not shown), the suction port 24 of the upper cylinder cover 24 of the left cylinder 22.
It is inhaled from 0 and enters the suction chamber 242.

The right and left pistons 21 pass the gas in the first space 221 through the check valve 214 and transfer it to the second space 222 when moving from the bottom dead center to the top dead center (push stroke).
That is, as the right piston 21 moves from the bottom dead center to the top dead center, the check valve 214 of the right piston 21 opens due to the difference between the pressure of the gas sucked in the pull stroke and the valve leaf spring pressure. , The gas in the first space 221 passes through the check valve 214,
Move to the second space 222. At this time, the suction valve 241 and the discharge valve 251
And are closed. Similarly to the piston 21 on the right side, in the piston 21 on the left side, the gas in the first space 221 passes through the check valve 214 and moves to the second space 222.

In the second space 222, the bellows type piston rod shaft sealing device 26 has one end of the bellows as a lower cylinder cover.
Since it is attached to 25 and the other end is attached to the cross head 11, the gas transferred from the second space 222 into the veloz in the pulling stroke returns to the second space 222 as it is in the next pushing stroke. That is, the vacuum gas does not leak from the second space 222 to the crank motion part 1, and the external gas does not enter the second space 222 from the vicinity of the crosshead 11.

EFFECTS OF THE INVENTION The multistage reciprocating vacuum pump of the present invention does not generate a couple force due to the displacement of the position of the crankpin, so that it is possible to completely eliminate vibration during operation. Compared with, it can contribute to weight reduction and size reduction as it is thinner. Also, because we have succeeded in making the crank motion part oil-free,
The distance piece (spacer) chamber and oil stopper are not required, and the piston rod can be shortened, which contributes to size and weight reduction.

Further, the multistage reciprocating vacuum pump of the present invention, the piston,
Since the check valve that allows the gas to pass through the piston in the push stroke is provided, the gas sucked into the first space in the cylinder in the pull stroke can be transferred to the second space in the push stroke through the check valve in the second stroke. Since the gas can be discharged from the second space through the discharge valve in the stroke, even a multi-stage reciprocating vacuum pump does not require the conventional long gas passage, and can contribute to the size reduction and weight reduction.

Furthermore, in the multistage reciprocating vacuum pump of the present invention, since the piston moving part and the crank moving part are both oilless, there is no risk of oil being diffused back and mixed into the vacuum exhaust system passage.
A clean high vacuum can be obtained.

[Brief description of drawings]

The drawings show an embodiment of the present invention, FIG. 1 is an overall sectional view, FIG. 2 is a partial sectional view, and FIG. 3 is a perspective view of each portion of a discharge valve.
FIG. 4 is a perspective view of each part of the check valve and the suction valve. 1 …… Crank motion part 2 …… Piston motion part 11 …… Crosshead 21 …… Piston 214 …… Check valve 22 …… Cylinder 24 …… Upper cylinder cover 241 …… Suction valve 25 …… Lower cylinder cover 251 …… Discharge valve 26 ... Piston rod shaft seal device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliographic references Sho 49-25011 (JP, U) Real public Sho 49-36243 (JP, Y1) Special public Sho 60-22198 (JP, B2)

Claims (3)

[Claims] 1. A multi-stage reciprocating vacuum wherein two lubricated parts of a crank motion part and a piston motion part are all oil-free, and two pistons are horizontally opposed to each other and piston load action lines are formed in a straight line. A pump, in which two cylinders are respectively sealed by an upper cylinder cover provided with a suction valve and a lower cylinder cover provided with a discharge valve, and the two pistons are respectively pushed in a pushing stroke. A multistage reciprocating vacuum pump, characterized in that a check valve is provided to allow gas to pass through the piston. 2. The multistage reciprocating vacuum pump according to claim 1, wherein the suction valve and the discharge valve are both closed in the pushing stroke and are opened in the pulling stroke. 3. The multistage reciprocating device according to claim 1, wherein said lower cylinder cover comprises a piston rod shaft sealing device having one end of a bellows attached to said lower cylinder cover and the other end attached to a crosshead. Dynamic vacuum pump.