Patent US4893985A successfully refreshed from Google Patents.
US4893985A
Expired / Lapsed
US
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Multi-stage molecular pump
Assignee: Pfeiffer Vacuum Technology AG
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Filing: 1988-08-15
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Granted: 1990-01-16
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Expires: 2008-08-15
Abstract
Abstract A molecular pump of the Hollweck type is composed of a plurality of stages in order to improve the pumping characteristics. Rotor and stator consist of different portions which are provided alternately with helical grooves and with smooth outer and inner surfaces respectively. The cooperating surfaces of the individual rotor and stator portions are tapered.
Inventors
- 👤 Kurt Holss
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 20:57
CPC Classifications
F; F04; F04D; F04D19/00; F04D19/02; F04D19/04; F04D19/044
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
89 words
A molecular pump for handling gases comprising a rotor and a stator which are disposed concentrically to one another, the rotor being inside the stator, wherein rotor (2) and stator (5) each consist of a plurality of portions (8,9; 10,11) which together form a plurality of pump stages and each pump stage is in turn composed of various pump sections, wherein the rotor (2) consists alternately of portions (8) which are provided with helical grooves at the outside, and of portions (9) the outer surfaces of which are smooth.
Claim 2
Dependent Claim
89 words
A molecular pump for handling gases comprising a rotor and a stator which are disposed concentrically to one another, the rotor being inside the stator, wherein rotor (2) and stator (5) each consist of a plurality of portions (8,9; 10,11) which together form a plurality of pump stages and each pump stage is in turn composed of various pump sections, wherein the rotor (2) consists alternately of portions (8) which are provided with helical grooves at the outside, and of portions (9) the outer surfaces of which are smooth.
Claim 3
Dependent Claim
36 words
A molecular pump according to claim 1, wherein the stator (5) consists alternately of portions (10) which are provided with helical grooves at the inside, and of portions (11) the inner surfaces of which are smooth.
Claim 4
Dependent Claim
42 words
A molecular pump according to claim 2, wherein the portions of the rotor with a smooth outer surface and the portions of the stator with a smooth inner surface lie with their external and internal tapers respectively on the same generated surface.
Claim 5
Dependent Claim
23 words
A molecular pump according to claim 2, wherein the depth of the helical grooves decreases from the suction side towards the discharge side.
Claim 6
Dependent Claim
23 words
A molecular pump according to claim 2, wherein the width of the helical grooves decreases from the suction side towards the discharge side.
Claim 7
Dependent Claim
107 words
A molecular pump according to claim 1, wherein one pump section of a pump stage is formed from part of a portion (8) of the rotor with helical grooves and from a portion (11) of the stator with a smooth inner surface, two pump sections each being formed from a part of a portion (8) of the rotor with helical grooves and from a part of a portion (10) of the stator with helical grooves, and one pump section being formed from a portion (9) of the rotor with a smooth outer surface and from a part of a portion (10) of the stator with helical grooves.
Claim 8
Dependent Claim
31 words
A molecular pump according to claim 1 wherein the individual portions of the rotor are tapered at their outside and the individual portions of the stator are tapered at their inside.
Claim 9
Dependent Claim
20 words
A molecular pump according to claim 7, wherein the larger diameters of the tapers are disposed towards the suction side.
Claim 10
Dependent Claim
20 words
A molecular pump according to claim 7, wherein the larger diameters of the tapers are disposed towards the discharge side.
Claim 11
Dependent Claim
29 words
A molecular pump according to claim 1, wherein the axial extent of the individual pump sections decreases from the suction suction side towards the discharge side of the pump.
Claim 12
Dependent Claim
23 words
A molecular pump according to claim 1, wherein the pitch of the helical grooves decreases from the suction side towards the discharge side.
References Cited (Backward Citations)
FR887499A
Cited
DE2409857A1
Cited
US4746265A
Cited
US4645413A
Cited
US4684317A
Cited
US4732530A
Cited
US4668160A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-01-15 | 1993-07-17 | 1994-01-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-15 | 1997-07-17 | 1998-01-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-15 | 2001-07-17 | 2002-01-16 | $7700.00 | Window Closed / Lapsed |