US5755554A
Expired / Lapsed
US
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Multistage pumps and compressors
Assignee: Weir Engineering Services Ltd
•
Filing: 1996-12-18
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Granted: 1998-05-26
•
Expires: 2016-12-18
Abstract
Abstract A multistage pump or compressor includes a series of axial flow stages. Each stage comprises an impeller for imparting whirl to the pumped fluid in one direction and a stator including vanes for imparting whirl to the pumped fluid in the opposite direction. The stator vanes define flow passages configured such that the fluid flows through the passages at substantially constant absolute velocity. The average ratio of stage axial length to impeller diameter for each axial flow stage is less than 0.4.
Inventors
- 👤 Michael Leslie Ryall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 19:58
CPC Classifications
F; F04; F04D; F04D31/00; F04D19/00; F04D19/02; F04D19/028; F04D29/00; F04D29/40; F04D29/52; F04D29/54; F04D29/541; F04D29/542; F04D29/544; F04D29/548; F04D3/00
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
96 words
A multistage pump for pumping fluid, the pump including a series of axial flow stages, each stage comprising an impeller for imparting whirl to the pumped fluid in one direction and a stator including vanes for imparting whirl to the pumped fluid in the opposite direction, the stator vanes defining flow passages configured such that, at or near the flowrate at which stage efficiency is a maximum, the fluid flows therethrough at substantially constant absolute velocity, and the average ratio of stage axial length to impeller diameter for each axial flow stage being less than 0.4.
Claim 2
Dependent Claim
96 words
A multistage pump for pumping fluid, the pump including a series of axial flow stages, each stage comprising an impeller for imparting whirl to the pumped fluid in one direction and a stator including vanes for imparting whirl to the pumped fluid in the opposite direction, the stator vanes defining flow passages configured such that, at or near the flowrate at which stage efficiency is a maximum, the fluid flows therethrough at substantially constant absolute velocity, and the average ratio of stage axial length to impeller diameter for each axial flow stage being less than 0.4.
Claim 3
Dependent Claim
25 words
The pump of claim 1, wherein the average ratio of stage axial length to impeller diameter for each axial flow stage is less than 0.3.
Claim 4
Dependent Claim
26 words
The pump of claim 2, wherein the average ratio of stage axial length to impeller diameter for each axial flow stage is between 0.2 and 0.25.
Claim 5
Dependent Claim
26 words
The pump of claim 1, wherein the average stage head coefficient ##EQU4## has a value greater than 0.3 at the best efficiency flow of the pump.
Claim 6
Dependent Claim
37 words
The pump of claim 1, wherein each axial flow impeller has a hub and blades mounted on the hub and defining tips, and the mean hub\tip diameter ratio of each axial flow impeller is greater than 0.7.
Claim 7
Dependent Claim
21 words
The pump of claim 1, wherein each impeller has an inlet flow co-efficient ##EQU5## with a value of less than 0.4.
Claim 8
Dependent Claim
21 words
The pump of claim 6, wherein each impeller has an inlet flow co-efficient with a value of between 0.15 and 0.25.
Claim 9
Dependent Claim
15 words
The pump of claim 1, wherein each axial flow impeller has more than five blades.
Claim 10
Dependent Claim
31 words
The pump of claim 1, wherein the impeller of each axial stage has blades defining a tip diameter, and the blade pitch/chord ratio at the tip diameter is less than 0.8.
Claim 11
Dependent Claim
81 words
The pump of claim 1, wherein, in the stator of each axial stage, the stator vanes are arranged to change the direction of absolute flow velocity of the fluid by between 80° and 120°, such that, at or near the flowrate at which the stage efficiency is a maximum, the whirl component of the fluid velocity leaving the stator is approximately the same as the whirl component of the fluid as it enters the stator vanes, but in the opposite direction.
Claim 12
Dependent Claim
13 words
The pump of claim 1, wherein each axial flow stator has impulse-type blades.
Claim 13
Dependent Claim
15 words
The pump of claim 1, wherein each axial flow stator has more than 30 blades.
Claim 14
Dependent Claim
29 words
The pump of claim 1, wherein each axial flow stator has blades of small axial chord length and less than 15% of the tip diameter of the stator blades.
Claim 15
Dependent Claim
36 words
The pump of claim 1, wherein each axial flow stator has more than thirty impulse-type blades, the blades being of small axial chord length and less than 15% of the tip diameter of the stator blades.
Claim 16
Dependent Claim
38 words
The pump of claim 1, wherein the impellers are mounted on a shaft and the cumulative axial thrust is at least partially balanced by one of a balance drum and balance disc mounted on the impeller mounting shaft.
Claim 17
Dependent Claim
22 words
The pump of claim 1, wherein the first pump stage is selected from one of a centrifugal, mixed and axial flow type.
Claim 18
Dependent Claim
31 words
The pump of claim 1, wherein axial clearance between the impellers and the stators is maintained by limiting the axial movement of an impeller mounting pump shaft by a thrust bearing.
Claim 19
Dependent Claim
33 words
The pump of claim 17, wherein the thrust bearing is selected from one of a hydrostatic type lubricated with fluid from high pressure regions of the pump, and an external, oil lubricated type.
Claim 20
Dependent Claim
37 words
The pump of claim 1, wherein the pump has a shaft radially supported by bearings lubricated with fluid from high pressure regions in the pump, so that the bearings are substantially hydrostatic with a high radial stiffness.
Claim 21
Dependent Claim
17 words
The pump of claim 1, wherein the stators are radially located and housed within a bored tube.
Claim 22
Dependent Claim
15 words
The pump of claim 20, wherein the stators are secured to the tube by keys.
Claim 23
Dependent Claim
22 words
The pump of claim 1, wherein the stators are held against rotation by axial clamping from the ends of the stator stack.
Claim 24
Dependent Claim
24 words
The pump of claim 22, wherein the impellers are axially clamped together by securing members at each end of an impeller mounting pump shaft.
Claim 25
Dependent Claim
26 words
The pump of claim 1, wherein the stators and impellers are mounted on hubs and the hub profile for both the stators and rotors is cylindrical.
Claim 26
Dependent Claim
26 words
The pump of claim 1, wherein the stators and impellers are mounted on hubs and the hub profile for both the stators and rotors is conical.
Claim 27
Dependent Claim
22 words
The pump of claim 1, where the impeller and stator blade heights are progressively reduced in consecutive stages or groups of stages.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-05-25 | 2001-11-24 | 2002-05-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-05-25 | 2005-11-24 | 2006-05-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-05-25 | 2009-11-24 | 2010-05-26 | $7700.00 | Window Closed / Lapsed |