Rotary kinetic fluid motors or pumps – Smooth runner surface for working fluid frictional contact
Utility Patent
1999-02-05
2001-01-02
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
Smooth runner surface for working fluid frictional contact
C415S143000, C415S199400
Utility Patent
active
06168374
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a friction vacuum pump having at least one turbomolecular pump stage joined at its pressure side to a screw pump stage.
It is known to increase the forevacuum tolerance of turbomolecular pumps by arranging, downstream of its turbomolecular stages, a screw stage. The problem of effectively utilising the screw pump stage is, that an effective pumping performance at the inlet of the screw (suction side of the screw) independent of the pressure as far as possible, can not be ensured. The reason for this is, that the flow characteristic of the pumped gases in the transition region between turbomolecular pump stages and screw pump stages changes from the molecular type (at pressures below 10−3 mbar) to the laminar type (from about 10−2 mbar and above). Known designs of the transition region between the turbomolecular pump stages and the screw pump stages have the disadvantage of the flow breaking away. This will considerably impair the pumping performance of the pump.
From DE-A-36 27 642 (claim 4) a friction pump of the kind affected here is known. The turbomolecular stage is followed by a downstream screw pump stage. The inlet of the screw pump stage has not been designed in any special manner. The depth of the screw does not change across the length of the screw pump stage.
SUMMARY OF THE INVENTION
It is the task of the present invention to improve the pumping performance of a friction pump of the aforementioned kind by an improvement to the inlet region of the screw pump stage.
This task is solved through the present invention by the characteristic features of the patent claims.
The measures according to the present invention have the effect that the transition region between the turbomolecular pump stage and the screw pump stage is geometrically adapted to match the type of flow. The flow which changes in this transition region from a molecular flow to a laminar flow is only impaired to an insignificant extent. The flow will not breakaway. The properties of the filling stage are adapted to mass flow, implemented degree of compression and absolute pressure.
In one of the advantageous designs, several or all blades of the filling stage are designed as blade-like shaped end sections of the ridges of the screw stage. This simplifies the manufacture of both filling and screw stage.
REFERENCES:
patent: 3947193 (1976-03-01), Maurice
patent: 4684317 (1987-08-01), Luijten et al.
patent: 4708586 (1987-11-01), Sawada et al.
patent: 4732529 (1988-03-01), Narita et al.
patent: 4797062 (1989-01-01), Deters et al.
patent: 5051060 (1991-09-01), Fleischmann et al.
patent: 5217346 (1993-06-01), Ikegami et al.
patent: 5238362 (1993-08-01), Casaro et al.
patent: 5553998 (1996-09-01), Muhlhoff et al.
patent: 5695316 (1997-12-01), Schutz et al.
patent: 2629877 (1989-10-01), None
patent: 2232205 (1991-11-01), None
Beyer Christian
Odendahl Heinz-Dieter
Stolle Robert
Leybold Vakuum GmbH
Look Edward K.
McAleenan James M.
Wall Marjama & Bilinsk
LandOfFree
Friction vacuum pump does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Friction vacuum pump, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Friction vacuum pump will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2541516