JP2865888B2 - Multi-turbo type vacuum pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large-capacity multi-turbo vacuum pump capable of evacuating a large volume from a high vacuum to the atmospheric pressure at once.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional vacuum pump. In FIG. 3, the high vacuum pump 15 is a turbo molecular pump,
It is connected to the auxiliary pump 16 by a pipe 17. The gas compressed by the high vacuum pump 15 is further compressed by the auxiliary pump 16 via the pipe 17 and exhausted to the outside.

[0003]

In order to increase the exhaust capacity of a turbo-molecular pump, it is necessary to increase the area where the gas is swept and to increase the rotational speed of the rotor. In order to increase the scraping area, the diameter of the rotor blade is increased to increase the area of the rotor, and at the same time, the inclination angle α of the blade on the high vacuum side is set to approximately 40 to 45 °, so that gas molecules are formed in the cascade. It is necessary to increase the opening area into which the air enters and the exhaust efficiency thereof.

However, the rotor 18 of the turbo molecular pump
As shown in FIGS. 4 and 5, the radially widened blade pieces 18a widen toward the outer diameter side, and the gap from the upper part to the lower part eventually becomes larger as shown in FIG. It becomes a see-through state that can be seen. The outer peripheral velocity of the rotor is limited to about 300 to 400 m / s due to the limitation of material strength. However, since the molecular velocity of light gas (hydrogen, helium, etc.) is as high as 1000 to 1500 m / s, see-through is not possible. If there is a part, the efficiency of compression / exhaust is reduced because the part can freely pass through the gap.

In order to avoid this, it is necessary to reduce the inclination angle α of the rotary blade piece 18a and increase the axial length of the rotary blade piece 18a as shown in FIG. The exhaust capacity is reduced, and in the latter case, the rotating body becomes longer, causing problems such as rotational performance and cost. Further, there is a method of changing the inclination angle α of the rotary blade piece 18a toward the outer periphery, but there are disadvantages such as production cost and generation of a torsional moment due to centrifugal force.

FIG. 8 shows an analysis result of the relationship between the above various parameters and the exhaust speed. Due to the above limitations, the displacement of currently available turbo molecular pumps is several thousand l / s
It is about ec, and even recently announced ones are only about 20,000 l / sec. Also, the compression ratio is low, and several Torr
Since it can be compressed only to the extent that the pressure can be reduced to the atmospheric pressure, a two-stage configuration in which an auxiliary pump is connected to the exhaust side as shown in FIG.

An object of the present invention is to provide a multi-turbo type vacuum pump having a large capacity and capable of evacuating to the atmospheric pressure by solving these problems.

[0008]

The multi-turbo type vacuum pump of the present invention has the following measures. Inside the casing provided with a first intake port and the exhaust port, and incorporates a multiple turbo rotating body polyaxial, one of the same turbo rotating body is a turbo-molecular pump, the plurality below its lowermost wings Are arranged circumferentially. 2 In the first aspect of the present invention, each of the plurality of turbo type rotors arranged below the lowermost stage of the turbo molecular pump is:
This is a viscous vacuum pump in which rotating disks provided with spiral grooves are combined in multiple stages.

[0009]

According to the first aspect of the present invention, since a plurality of turbo type rotating bodies are built in a casing having a multi-axial intake port and an exhaust port, no intermediate piping is required, and a plurality of turbo type rotating bodies are required. Efficient exhaust is performed by the rotating body, and a small and large-capacity exhaust is possible.

Furthermore, by disposing the plurality of turbo rotation body below the lowermost blade of a turbomolecular pump, it is possible to prevent the gas is despread passes between turbomolecular pump blades. In addition, a plurality of turbo rotating bodies are arranged in a circle, and the turbo rotating bodies are arranged in a small space, and the blade diameter of the turbo molecular pump is increased to increase the displacement and improve the gas compression ratio. Can be done.

According to the second aspect of the present invention, in addition to the operation of the first aspect of the present invention, a spiral groove is provided below a lowermost blade of a turbo-molecular pump for exhausting by utilizing the behavior of gas as a molecule. There are multiple viscous vacuum pumps that combine rotating disks with multiple stages, compress using the viscosity of the gas, and evacuate by spiral grooves, and continuously use the different characteristics of the gas. An exhaust with a high compression ratio is performed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. The present embodiment relates to a multi-turbo vacuum pump in which a main turbo is a turbo molecular pump and a sub-turbo is a viscous pump.

In FIG. 1, a main turbo rotor 6 and a multi-stage main turbo vane 5 are vertically arranged in a casing 4 having a main turbo intake port 1 at an upper end, and the main turbo rotor 6 is a main turbo bearing. At 9, the radial and thrust directions are supported and driven by the main turbo motor 8. In addition, at the time of stop or abnormality, the main turbo emergency bearing 7 is brought into contact with the emergency bearing 7 to safely stop. Also,
Multi-stage radial main turbo rotor blades 6a are attached to each main turbo rotor 6, and the rotor blades 6a of each main turbo rotor are arranged between the main turbo stator blades 5 fixed to the casing 4. Vacuum exhaust is performed by knocking down gas molecules downward by the interaction between the two.

A plurality of sub-turbo rotors 11 are circumferentially arranged below the lowermost main turbo rotor rotor blade 6a, all of which are housed in the casing 4, and are multi-axial and non-contact. It has a structure that can rotate. The sub-turbo rotor 11 has a sub-turbo intake port 2 at the upper end, and is contained in a sub-turbo casing 12 arranged in the casing 4. It is designed to be driven. The sub-turbo rotor 11 has multi-stage sub-turbo rotor blades 11a. As shown in FIG. 2, each sub-turbo rotor blade 11a has a spiral shape provided at equal intervals on the entire upper and lower surfaces thereof. It has a disk shape having a plurality of grooves 11b. Sub-turbo stationary vanes 10 fixed in the sub-turbo casing 4 are arranged in a state of being alternately combined with the sub-turbo rotating blades 11a. In the lower part of the casing 4,
A sub-turbo exhaust port 3 on the atmosphere side is provided.

The main turbo rotor 6 is made of a composite material such as fiber reinforced metal (FRP) or fiber reinforced ceramics (FRC) to enable high peripheral speed rotation. It is made of and is designed to reduce thermal expansion. The main turbo bearing 9 is a magnetic bearing type, and the sub turbo bearing 14
Is a gas bearing type to have an oil-free structure.

In this embodiment constructed as described above, gas molecules from the main turbo intake port 1 are knocked down by the interaction between the multi-stage main turbo rotor blades 6a and the main turbo stationary blades 5. Then, evacuation is performed. The blown-down gas enters the sub-turbo casing 12 from the sub-turbo intake port 2. This gas is compressed by the viscous force between the sub-turbo rotor blades 11a and the sub-turbo stator blades 10 of each sub-turbo rotor 11 and passes through the spiral groove 11b to the outside of the sub-turbo rotor blades 11a. And is gradually compressed and exhausted downward by the multistage sub-turbo rotor blades 11a. Thus, in the sub-turbo rotor 11,
The gas finally reaches the atmospheric pressure and is discharged from the sub turbo exhaust port 3.

As described above, in the present embodiment, the exhaust is continuously performed by combining both the knocking down of the gas molecules in the main turbo rotor 6 and the compression and exhaust due to the viscosity of the gas in the sub turbo rotor 11. And high-compression ratio exhaust is possible.

The main turbo rotating body 6 and the sub turbo rotating body 11 are arranged vertically inside the casing 4 so that efficient piping and exhaust can be performed without the need for piping therebetween, and the size of the apparatus can be reduced. Is possible.

Since the sub-turbo rotor 11 is disposed below the lowermost rotor blade 6a of the main turbo rotor, gas passes through the see-through portion between the rotor blades 6a of the main turbo rotor. The maximum diffusion can be prevented. In addition, since a plurality of sub-turbo rotors 11 are arranged on the circumference, the arrangement space can be reduced, and the blade diameter of the rotor blade 6a of the main turbo rotor is increased to increase the displacement. And the gas compression ratio can be increased.

Furthermore, since the main turbo rotor 6 is made of a composite material, it can be rotated at a high peripheral speed to improve the exhaust performance, and the temperature becomes high due to the viscous force and compression action of the exhaust gas. By using a ceramic with low thermal expansion for the sub-turbo rotating body on the atmosphere side, it is possible to use gas bearings with small clearances and magnetic bearings with poor heat dissipation and thermal expansion problems. It is possible to use oil free without using.

[0021]

The present invention has the following effects.

(1) According to the first aspect of the present invention, a plurality of multi-shaft turbo-type rotating bodies are built in a casing provided with an intake port and an exhaust port to form a multi-turbo type, so that piping on the way is provided. Since it becomes unnecessary, exhaust loss and space loss can be reduced, and a small-sized, large-capacity exhaust vacuum pump with good exhaust efficiency can be obtained.

Further , by arranging a plurality of turbo-type rotors circumferentially below the lowermost blade of the turbo-molecular pump on the high vacuum side, the gas passes between the turbo-molecular pump blades and diffuses in reverse. In addition, the exhaust capacity can be increased by increasing the blade diameter of the turbo-molecular pump. In addition, by arranging a plurality of turbo-type rotating bodies in a circumferential shape, the size can be reduced.

( 2 ) In the present invention of claim 2 , in addition to the above, the gas is exhausted below the lowermost blade of the turbo-molecular pump utilizing the behavior of gas as a molecule by utilizing the viscosity of the gas. By arranging a plurality of viscous vacuum pumps in which rotary disks provided with spiral grooves are combined in multiple stages, continuous evacuation is performed using different characteristics of gas, and structural defects of turbo molecular pumps A high-compression ratio vacuum pump that can cover performance deterioration due to fate can be obtained, and evacuation from high vacuum to pressure such as atmospheric pressure can be performed at once.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a multi-turbo type vacuum pump according to one embodiment of the present invention.

FIG. 2 is a plan view of a sub-turbo rotary body rotor blade of the embodiment.

FIG. 3 is a conceptual diagram of a conventional vacuum pump.

FIG. 4 is an external view of a blade shape of a conventional turbo-molecular pump.

FIG. 5 is a longitudinal sectional view of a blade of a conventional turbo-molecular pump.

FIG. 6 is a side view of a blade of a conventional turbo-molecular pump.

FIG. 7 is a side view of a blade of a conventional turbo-molecular pump when see-through is eliminated.

FIG. 8 is a graph showing an analysis result regarding the maximum pumping speed efficiency of the turbo molecular pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main turbo intake port 2 Sub turbo intake port 3 Sub turbo exhaust port 4 Casing 5 Main turbo stator blade 6 Main turbo rotor 6a Main turbo rotor rotor blade 7 Main turbo emergency bearing 8 Main turbo motor 9 Main turbo bearing 10 Sub turbo stator blade 11 Sub turbo rotor 11a Sub turbo rotor rotor blade 12 Sub turbo casing 13 Sub turbo motor 14 Sub turbo bearing

──────────────────────────────────────────────────続 き Continuing from the front page (72) Takashi Arai 801 Mukaiyama, Naka-cho, Naka-machi, Naka-gun, Ibaraki Pref. 22 Hiroshima Works, Mitsubishi Heavy Industries, Ltd. (72) Inventor Satoshi Hata 4-22, Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Works, Mitsubishi Heavy Industries, Ltd. (56) References JP 1-277698 (JP, A) JP-A-63-75390 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F04D 19/04

Claims (2)

(57) [Claims] 1. A plurality of turbo-type rotating bodies are built in a multi-axis inside a casing provided with an intake port and an exhaust port .
One of the rotors is a turbo-molecular pump.
A multi-turbo type vacuum pump comprising a plurality of turbo type rotating bodies arranged circumferentially below a step blade . 2. Each of a plurality of turbo type rotors disposed below a lowermost blade of a turbo molecular pump is a viscous vacuum pump in which rotary disks provided with spiral grooves are combined in multiple stages. The multi-turbo type vacuum pump according to claim 1 , wherein: