JP3051515B2 - Multistage vacuum pump cooling system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for a multistage vacuum pump, and more particularly to a cooling device suitable for a multistage vacuum pump for exhausting sublimable or condensable gas.

[0002]

2. Description of the Related Art Conventionally, a multistage vacuum pump has been known in which a plurality of rotors having a plurality of rotors are provided adjacent to each other along a rotation axis, and the opposed rotors rotate in opposite directions to perform suction and exhaust. ing. The rotor for a multi-stage vacuum pump rotates without contact, with a small gap between the rotors facing each other and between the rotor and the casing.

In the above-described multi-stage vacuum pump, a cooling device is provided for removing compression heat generated in a compression process of a gas to be exhausted. As shown in FIG. 3, the conventional cooling device for a multi-stage vacuum pump includes a cooler 32 installed at a position separated from a casing 31 of the multi-stage vacuum pump, and connects the casing 31 and the cooler 32 by a conduit 33. I was The cooler 32 is provided for each stage of the vacuum pump requiring cooling. The system shown in FIG. 3 is called an intercooler type.

Next, another cooling device in a conventional multi-stage vacuum pump will be described with reference to FIG. This cooling device is what is called a jacket type, and water cooling chambers 41, 41 are provided on both outer sides of a casing 31 of a multi-stage vacuum pump.
It has. Thereby, the compression heat generated in each stage is cooled through the pump casing wall.

[0005]

However, in the cooling device of the multi-stage vacuum pump shown in FIG. 3 described above, a large installation space is required because the cooling device is installed at each stage apart from the casing. This necessitates a problem that the size of the entire multi-stage vacuum pump becomes large as a result.
Further, since the cooling device is separately provided at a position separated from the vacuum pump, there is a problem that the entire device becomes expensive.

On the other hand, in the jacket-type cooling device shown in FIG. 4, since the casing body is directly cooled by the coolant, the substance sublimated or condensed in the cooling section adheres and accumulates between the rotor and the casing. There is a problem that the pump may be overloaded or stopped due to the condensate.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and its object is to provide a cooler at a lower portion of a pump casing so that an intercooler becomes unnecessary.
An object of the present invention is to provide a cooling device for a multi-stage vacuum pump that can be made compact and that is suitable for exhausting sublimable or condensable gas by not cooling the casing body.

[0008]

In order to achieve the above-mentioned object, a cooling device for a multi-stage vacuum pump according to the present invention is provided with a cooling device for a multi-stage vacuum pump for removing compression heat generated in a compression process of exhaust gas. In the above, a single cooler for passing cooling water through a wall provided at a lower portion of the pump casing is provided, and this cooler allows each stage of the multistage vacuum pump to pass through a wall provided at a lower portion of the pump casing. The gas exhausted from the air is cooled.

[0009]

According to the cooling device for a multi-stage vacuum pump of the present invention having the above-described structure, a cooler is attached as a separate component to the lower part of the pump casing, cooling water is passed through the cooler, and provided at the lower part of the pump casing. By cooling the gas exhausted through the wall provided for each stage, an intercooler is not required, and the vacuum pump can be made compact. Is prevented from condensing in the casing.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A cooling device for a multistage vacuum pump according to the present invention will be described below with reference to FIGS.

FIG. 1 is a diagram showing the overall structure of a vacuum pump incorporating a cooling device according to the present invention, and FIG.
FIG. 2 is a cross-sectional view along the line II.

1 and 2, reference numeral 1 denotes a casing, in which a pair of rotating bodies 2 and 2 are disposed. The rotating body 2 includes a rotating shaft 3 and a plurality of rotors 4 arranged along the axial direction of the rotating shaft. The rotating body 2 is rotatably supported at one end by a bearing 5 and at the other end by a bearing 6. One rotating body 2 is connected to a motor 7. Then, from one rotating body 2 to the other rotating body 2
Is transmitted by a gear 8 (only one of the gears is shown in FIG. 1) fixed to the shaft end of the rotating shaft 3.
The pair of rotating bodies 2 and 2 rotate in directions opposite to each other, and the rotors 4 and 4 opposed to each other with a small gap rotate in directions opposite to each other, so that suction and exhaust are performed.

The bearing 5 is accommodated in a bearing case 10, and the bearing 6 and the gear 8 are accommodated in a bearing case 11. The bearings 5 and 6 and the gear 8 are lubricated with the lubricating oil in the bearing cases 10 and 11.

A lower wall 15 is provided below the pump casing 1 so as to close the opening 1a of the pump casing. A cooler 16 is attached to the lower wall 15. Cooling water is passed through the cooler 16. This cooler 16 removes the heat of compression of the gas exhausted from each stage. That is, as shown by arrows A and B in FIG. 2, the exhaust gas discharged from each stage once comes into contact with the lower wall 15 and then rises and is guided to the rotor chamber of the next stage. . Then, when the exhaust gas contacts the lower wall 15, the exhaust gas is cooled through the wall by the cooling water flowing in the cooler 16. As described above, in the present embodiment, since the cooler 16 is provided at the lower portion of the pump casing 1, even if the sublimable or condensable exhaust gas is cooled and condensed by the cooler 16, the condensate Will accumulate on the upper surface of the lower wall 15 below the pump casing 1, and there is no danger of accumulating between the rotor 4 and the pump casing 1.

Next, the flow path of the gas exhausted by the vacuum pump will be briefly described.
The gas that has flowed into the casing is moved from top to bottom by the rotor 4 for each stage. At this time, since the gas is compressed, the temperature rises due to the heat of compression. Thereafter, the gas comes into contact with the lower wall body 15 having the cooler 16 through which the cooling water disposed in the lower part of the pump casing 1 flows, and at this time, heat exchange is performed, and the exhaust gas is cooled. You. At this time, in the case of a sublimable or condensable gas, there is a possibility that the gas will condense and accumulate as condensate on the lower wall 15, but the lower wall 15 is slightly separated from the pump casing 1. Since there is no danger of condensate condensed between the rotor 4 and the casing 1, there is no possibility that the condensed matter will collect between the rotor 4 and the casing 1. Thus, for sublimable or condensable gases,
Since the cooler is not adjacent to the casing main body but located at the lower part of the pump casing, the pump main body can exhaust gas without being affected by sublimated and condensed substances by the cooler.

In the case of exhausting a gas that is not sublimable or condensable, a cooler can be attached to an inlet plate or the like above the pump.

[0017]

As described above, according to the cooling device for a multi-stage vacuum pump of the present invention, a cooler is attached as a separate component to the lower part of the pump casing, and the cooling water is passed through the cooler, thereby lowering the pump casing. By cooling the gas exhausted through the wall provided at each stage, an intercooler becomes unnecessary, and the entire vacuum pump can be made compact.

Further, according to the present invention, since the casing body is not cooled, the sublimable or condensable gas can be prevented from condensing in the casing, which is very suitable for sublimable or condensable exhaust.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the overall configuration of a multi-stage vacuum pump provided with a cooling device according to the present invention.

FIG. 2 is a sectional view taken along the line II-II of FIG.

FIG. 3 is a cross-sectional view showing a conventional cooling device for a multi-stage vacuum pump.

FIG. 4 is a sectional view showing another cooling device of the conventional multi-stage vacuum pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casing 2 Rotating body 3 Rotating shaft 4 Rotor 5, 6 Bearing 7 Motor 8 Gear 10, 11 Bearing case 15 Lower wall 16 Cooler

──────────────────────────────────────────────────続 き Continuation of the front page (72) Katsuaki Usui 4-2-1, Motofujisawa, Fujisawa-shi, Kanagawa Prefecture Ebara Research Institute, Inc. (56) References JP-A-2-70990 (JP, A) JP-A JP-A-2-95792 (JP, A) JP-A-4-19385 (JP, A) JP-A-52-27681 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) F04C 23 / 00-29/10 331

Claims (1)

(57) [Claims] 1. A cooling apparatus of a multi-stage vacuum pump for removing the compression heat generated in the compression process of the exhaust gases, single cooling which allows cooling water to pass therethrough wall member provided in the lower portion of the pump casing Vessel, and this cooler
A cooling device for a multi-stage vacuum pump, wherein gas exhausted from each stage of the multi-stage vacuum pump is cooled through a wall provided at a lower portion of a pump casing.