Rotary expansible chamber devices – Interengaging rotating members – Like rotary members
Patent
2000-01-03
2000-12-26
Denion, Thomas
Rotary expansible chamber devices
Interengaging rotating members
Like rotary members
29888023, F10C 118
Patent
active
061649457
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates in general to dry vacuum pumps used in semiconductor device manufacturing processes, for example, and method of making the pump, and relates in particular to a rotor for such a vacuum pump and its method of manufacture.
BACKGROUND ART
A type of dry vacuum pumps comprise a pair of rotors having lobes shaped in an involute or cycloid curvature. These rotors rotate inside a pump casing while closely coupled with the lobes to each other, thereby to pump fluid. Between the lobes, there is a clearance of about 100 .mu.m so as to avoid using a lubricant.
Many conventional rotors have been made from a solid block of material. There are various way of making such solid rotors, including a method of casting solid lobes and a shaft integrally; or casting solid lobes with an inserted solid shaft; or attaching lobes to a shaft with a key. However, such solid rotors are heavy and are difficult to handle during fabrication and assembly operations. Furthermore, they are loaded with a large inertial moment, and a large torque is required for their dynamic control. For these reasons, construction of a hollow rotor can be considered, where the rotors may be fabricated from sheet or plate materials.
In such pumps, since the hollow rotor is subjected to pressure change while the pump is operated, it is necessary to provide a vent hole in the rotor so that it is not deformed due to the pressure difference between the inside and outside of the rotor. However, in this case, there is a potential danger contaminating rusting of the interior of the rotor due to the effects of humidity in storage or corrosive process gases. Also. There may be a danger to humans from residual gases trapped inside the rotor which may be released during maintenance and repairs of the pump.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide a hollow rotor for use in a dry vacuum pump, and a method for making the hollow rotor. The rotor has a feature that its interior is free from invasion of water and is resistant to deformation from applied stresses normally encountered during the operation of such a vacuum pump.
The object has been achieved in a hollow rotor for use in a vacuum pump comprising: a rotor shell formed to conform to an outline of lobes; side-plates for covering transverse ends of the rotor shell; and a rotation shaft secured to the side-plates, wherein a hollow section formed by the rotor shell and the side-plates is under a vacuum environment.
Accordingly, because the rotor interior is a hermetic hollow structure, the pump is significantly reduced in weight, and achieves prevention of rust formation inside the rotor, and furthermore, by making the hollow section under a vacuum environment, any differential pressure which might be generated during the pumping operation is lessened.
In the rotor, a balancing hole bottoming within a thickness dimension of a side-plate may be provided on a surface location of the side-plate. Accordingly, without destroying the vacuum inside the hollow section, each rotor can be balanced for dynamic stability using the hole provided on the side-plate.
The hollow rotor may be produced according to a method including evacuating a hollow section formed within the rotor shell and the side-plates. The rotor shell and the side plates may be joined by welding.
The evacuation process may be conducted in such a way that at least a final hollow section forming process is conducted in a vacuum and/or high temperature environment thereby to make a vacuum within the hollow rotor.
Or, the hollow section may be evacuated through a vacuum passage provided in the hollow rotor, which is hermetically sealed off after evacuation is completed.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a longitudinal view of a partially cutaway vacuum pump of the present invention;
FIG. 2 is a transverse cross sectional view of the embodiment shown in FIG. 1;
FIG. 3 is a transverse cross sectional view through a plane A--A in FIG. 1;
FIG. 4 is a transverse cross sectiona
REFERENCES:
patent: 56614 (1866-07-01), Roots et al.
patent: 571770 (1896-11-01), Kurz
patent: 1030083 (1912-06-01), Green
patent: 2944732 (1960-07-01), Lorenz
patent: 3302868 (1967-02-01), Wrede
patent: 4938670 (1990-07-01), Lee
patent: 4974318 (1990-12-01), Heppekausen et al.
patent: 5895210 (1999-04-01), Nakaniwa et al.
Arai Satoshi
Ishibashi Yoshimitsu
Usui Katsuaki
Denion Thomas
Ebara Corporation
Trieu Theresa
LandOfFree
Vacuum pump rotor and method of manufacturing the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vacuum pump rotor and method of manufacturing the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vacuum pump rotor and method of manufacturing the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-988695