JPH02259297A - Vacuum pump - Google Patents

Abstract

PURPOSE:To get high compression performance without enlargement in length of a stationary cylinder and a rotary cylinder by performing compression exhaust of gas through providing helicoidal grooves on opposite surfaces formed through inserting the rotary cylinder into a gap between plural stationary cylinders. CONSTITUTION:Many rotor blades 11 are extended horizontally on a periphery of a rotor 21 fixed to a rotor shaft 3, while stationary blades 12 are held on an inner circumference of a casing 4 through stator spacers 41. A turbine is made up by inserting the stator blades 12 between the rotor blades 11. A rotary cylinder 23 is extended downwards as a monoblock part of the rotor 21 and has a helicoidal groove 23a on its outer periphery in the range below the rotor blades 11, while the lowest stator spacer 41a has a double cylindrical structure which is formed by folding it inwards so as to have an outer cylinder 42 and an inner cylinder 44 having a helicoidal grooves 44a on its outer periphery. Compression exhaust of gas becomes possible by inserting the rotary cylinder 23 between both of the cylinders 42 and 43. A main exhaust port 51 and an auxiliary exhaust port 52 are formed on the opposite side of a pump base 33.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a vacuum pump that compresses and exhausts gas using thread grooves.

[Prior Art] Conventional pumps of this type generally have a rotor rotatably disposed within an outer cylinder, and a spiral thread groove is carved on the inner circumferential surface of the outer cylinder or the outer circumferential surface of the rotor. It is true. When the rotor rotates, the thread groove has the ability to draw in surrounding gas using its viscous resistance and forcibly entrain it to the exhaust port. In addition to being used alone, such a thread groove pump is often used in conjunction with the lower stage of a turbo-molecular pump.

[Problem to be solved by the invention] However, in this type of pump, the compression capacity cannot be effectively exhibited unless the thread groove is provided with a certain length. Therefore, in practical use, the rotor becomes quite elongated, which leads to an increase in the size of the pump. There is a problem that can lead to

The present invention first takes measures to improve compression performance without increasing the size of the pump.

Furthermore, when considering the intended use of a thread groove pump, simply having high compression performance may not be sufficient.

For example, in a helium leak detector, it is necessary to once evacuate the inside of the chamber to a high vacuum in order to clean it, but it is necessary to leave He gas that leaks out in the chamber side as much as possible after that. However, if the compression performance is high, all of the leaked He gas will be exhausted and will no longer reach the He detector. Furthermore, in a CVD apparatus or the like, there are times when it is desired to introduce a certain type of gas from the outside after cleaning the inside of the chamber, but such setting conditions cannot be satisfied simply by having high compression performance.

The present invention aims to realize a vacuum pump that has high compression performance and can be suitably used for the above-mentioned purposes.

[Means for Solving the Problems] In order to achieve the above object, the present invention employs the following configuration.

That is, in the vacuum pump of the present invention, a rotary cylinder is inserted into a gap between a plurality of fixed cylinders arranged concentrically on a base, and a thread groove is formed on the opposing surfaces of the two cylinders, so that at least the outer diameter of the rotary cylinder is connected to the inner diameter of the rotary cylinder. In addition, the base is provided with a main exhaust port and an auxiliary exhaust port, and the main exhaust port is communicated with the end of the thread groove, and the auxiliary exhaust port is connected to the end of the thread groove. It is characterized by communication upstream from the end of the groove.

[If the gas is continuously compressed and exhausted from the outer diameter part of the rotary cylinder to the inner diameter part by the action screw groove, the compression performance can be improved without making the fixed cylinder or the rotating cylinder long. Moreover,
Since the main exhaust port communicates with the end of the thread groove, a high compression ratio can be obtained, whereas the auxiliary exhaust port communicates upstream of the end of the thread groove, so the compression ratio is not so high. Therefore, by selectively using these, the compression ratio can be varied, and problems caused by improved compression performance can be compensated for. Furthermore, it becomes possible to use the system by allowing a certain type of gas to flow back from the auxiliary exhaust port while exhausting the gas from the main exhaust port, which is convenient when it is desired to send gas for a specific purpose.

[Example code] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the vacuum pump of this embodiment.

The rotor 21 is fixed to the rotor shaft 3, and has a large number of rotor blades 11 horizontally protruding from its outer periphery. On the other hand, on the inner periphery of the casing 4, a large number of status spacers 41 are stacked on the base 33.

These status spacers 41 are ring-shaped, and each is placed on the lower status spacer 41 in a positioned state. The stator blades 12 are sandwiched between the stator spacers 41, and the stator blades 12 are inserted between the rotor blades 11 of the rotor 21 to form the turbine 1.

The cross-sectional area of the turbine 1 is set to gradually decrease from the intake port 34 side toward the exhaust port 51 (52) side so that gas can be compressed.

On the other hand, below the moving blades 11 of the rotor 21, a rotary cylinder 23 having a spiral thread groove 23a formed around its outer periphery is integrally suspended. On the other hand, the lowermost status spacer 41a has a double-tube structure bent inward so that the outer tube 41a
2 and the inner cylinder 44 are used as the fixed cylinder of the present invention,
A spiral thread groove 43a is formed on the upper surface of the bottom plate portion 43, and a spiral thread groove 44a is formed around the outer periphery of the inner cylinder 44. The rotary cylinder 23 is inserted between the outer cylinder 42 and the inner cylinder 44. These thread grooves 23a
s 43 a % 44 a is set so that the volume space gradually decreases toward the exhaust direction, making it possible to continuously compress and exhaust gas from the outer diameter part to the inner diameter part of the rotating cylinder part 23. There is.

Further, a main exhaust port 51 and an auxiliary exhaust port 52 are opened at opposite positions of the pump base 33. The main exhaust port 51 is communicated with the terminal end of the thread groove 44a, and the auxiliary exhaust port 52
is communicated with the thread groove 43a located upstream from the threaded groove 43a through the vertical hole 52a.

With the above configuration, this vacuum pump exhibits wide-area characteristics with exhaust capability in the viscous flow region by the thread grooves 23 a s 43 a s 44 a and exhaust capability in the molecular flow region by the turbine 1. It becomes something you get. In particular, by providing the thread grooves 23a, 43a, and 44a, it is possible to increase the effective length without making the rotor 21 long, resulting in a small pump with excellent compression performance.

Furthermore, since the main exhaust port 51 communicates with the end of the thread groove 44a, a high compression ratio can be obtained by connecting a back pump or the like here, whereas the auxiliary exhaust port 52 communicates with the end of the thread groove 43a, which is located upstream of the main exhaust port 51. Because it communicates with the pump, even if a back pump or the like is connected here, a very high compression ratio cannot be obtained. Therefore, by utilizing this fact and selectively using both the exhaust ports 51 and 52, it becomes possible to use the compression ratio in two stages, and the problems caused by improving the compression performance can be compensated for.

In addition, it is possible to exhaust gas through the main exhaust port 51 while causing a certain type of gas to flow backwards toward the intake port 34 from the auxiliary exhaust port 52, which can be used to send gas for purposes of use. .

Here, I will briefly introduce a usage example. FIG. 2 shows a case where the vacuum pump P of this embodiment is applied to a helium leak detector. The helium leak detector places the fuel rod A etc. to be detected in the chamber C1,
This device detects He gas leakage from the fuel rod A by introducing He gas into the fuel rod A and evacuating the chamber C using the detector 2. In this case, if the evacuation performance of the connected vacuum pump is too high, He will not be able to reach the detector ■ properly, but this pump P1 will initially connect the back pump P2 to the main exhaust port 51 to evacuate the chamber C1 to a high vacuum. Then, when the back pump P2 is connected to the auxiliary exhaust port 52 by switching the valve V, the He gas that leaks thereafter is moderately back-diffused within the pump P1 and introduced into the detector I. Become.

Further, FIG. 3 shows a case where this vacuum pump P1 is applied to a CVD apparatus. H2 in chamber C2 of the same device
When you want to introduce gas, use the main exhaust port 51 of the main pump P1.
By attaching a back pump P2 to perform high vacuum evacuation, and introducing a small amount of H2 gas from the auxiliary exhaust port 52,
It is possible to create an H2-rich state without changing the gas pressure inside the chamber C2.

Although one embodiment of the present invention has been described above, the thread grooves may be provided on the opposite side of each opposing surface, and the rotating cylinders may be added in two or three layers. Further, the pump may be configured only with thread grooves. Furthermore, the applications can be expanded by setting two or more auxiliary exhaust ports, and the applications are not limited to those described in the above embodiments. In addition, various modifications can be made to the configuration of each part without departing from the spirit of the present invention.

[Effects of the Invention] With the above configuration, the present invention can obtain a high compression ratio without increasing the size of the pump, and
A high-performance, high-value-added vacuum pump that can be used at low compression ratios by using an auxiliary exhaust port, and can also be used when you want to reverse diffuse only a specific gas by using both exhaust ports at the same time. It is possible to provide

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is an overall vertical sectional view of a vacuum pump, and FIGS. 2 and 3 are explanatory diagrams for explaining an example of use. 23a, 43a, 44a...Thread groove 3...Rotating tube 3...Base 2.44...Fixed tube 1...Main exhaust port 2...Auxiliary exhaust port

Claims (1)

[Claims] A rotating cylinder is inserted into the gap between multiple fixed cylinders arranged concentrically on the base, and thread grooves are formed on the opposing surfaces of the two cylinders to continuously compress and exhaust gas from at least the outer diameter part of the rotating cylinder to the inner diameter part. At the same time, the base is provided with a main exhaust port and an auxiliary exhaust port, so that the main exhaust port communicates with the terminal end of the thread groove, and the auxiliary exhaust port communicates upstream of the terminal end of the thread groove. A vacuum pump characterized by: