Rotary kinetic fluid motors or pumps – Smooth runner surface for working fluid frictional contact
Patent
1995-10-30
1997-12-09
Verdier, Christopher
Rotary kinetic fluid motors or pumps
Smooth runner surface for working fluid frictional contact
415143, 4174234, F01D 136
Patent
active
056953160
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCES TO RELATED APPLICATIONS
This application claims benefit under 35 U.S.C. .sctn.120 of PCT international application PCT/EP94/01011, filed on Mar. 31, 1994.
BACKGROUND OF THE INVENTION
The invention relates to a friction vacuum pump with pump sections of different designs, of which the pump section on the inlet side consists of turbomolecular pump stages and a further pump section of Siegbahn stages with spiral grooves, whereby the active pumping surfaces of the Siegbahn stages are formed by facing surfaces of an annular rotor disc and an annular stator disc.
The class of friction vacuum paps comprises Gaede mercury pumps (wherein a cylinder, having both a pump slot and a barrier slot arranged between the inlet and the outlet, rotates within a housing), Holweck pumps (wherein a cylinder having spiral grooves arranged on the stator or on the rotor rotates within a housing), Siegbahn pumps (rotating and stationary annular discs with spiral grooves), and turbomolecular pumps (equipped with rotating and guiding blades). It is known to equip friction pumps with differently designed pumping sections.
A friction pump of the aforementioned kind is known from DE-OS 39 22 782. In this known friction pump the rotor discs of the Siegbahn stage are equipped with the spiral grooves. Production of a friction pump of this kind is relatively involved, since not only its stator but the rotor too must be manufactured and assembled from a large number of individual parts.
It is the task of the present invention to simplify the production of a friction vacuum of the aforementioned kind.
SUMMARY OF THE INVENTION
According to the present invention this task is solved for a friction vacuum pump of the aforementioned kind by equipping the annular stator discs with the spiral grooves. Through this measure it is on the one hand no longer required to produce the rotor from numerous individual parts. The rotor can be formed from a single piece and may be cut from a single solid piece for example. Moreover, adaptation of a friction pump of the kind addressed here with regard to different applications is simplified because in vacuum pumps of the this kind the properties of the spiral grooves (depth, width, pitch) determine the pump's characteristics. When wanting to change the pump's characteristics in the case of a friction pump built according to the state of the art, stator and rotor will have to be disassembled after each other, the rotor discs with the spiral grooves will have to be exchanged and then rotor and stator will have to be fitted again. In a friction vacuum pump built according to the present invention only the stator will have to be disassembled and reassembled with exchanged discs.
A further advantage of the measure according to the present invention is that the pump section with the Siegbahn stages is followed by at least one further pump stage of any kind--preferably following a friction pump--which has in the intermediate range between molecular flow and viscous flow, good pumping characteristics. With a so designed vacuum pump it is possible to generate a relatively high backing pressure (over 10 mbar), so that pumps of this kind may be operated with small and cheap backing pumps.
BRIEF DESCRIPTION OF THE DRAWINGS
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.
Further advantages and details of the present invention shall be explained on the basis of the design examples of the drawing FIGS. 1 to 18.
FIG. 1 shows a sectional view of a friction vacuum pump according to an embodiment of the present invention.
FIG. 2 shows a sectional view along line II--II through the pump of FIG. 1 at a level of a stator disc of a Siegbahn stage.
FIG. 3 shows a sectional view along line III--III through the pump of FIG. 1 at a level of a pump stage downstream of the Siegbahn stage.
FIG. 4 shows a sectional view of a
REFERENCES:
patent: 1975568 (1934-10-01), Dubrovin
patent: 3969039 (1976-07-01), Shoulders
patent: 4732529 (1988-03-01), Narita
patent: 5219269 (1993-06-01), Ikegami et al.
patent: 5358373 (1994-10-01), Hablanian
Journal of Vacuum Science & Technology, vol. 8, No. 5, Sep. 1990, New York, US pp. 3870-3873, XP000147920 J. Y. Tu `A new design for the disk-type molecular pump`.
Englander Heinrich
Henning Hinrich
Schutz Gunter
von Schulz-Hausmann Friedrich Karl
Leybold Aktiengesellschaft
Verdier Christopher
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