US3792935A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rotary-shaft liquid handling machine
Assignee: Weir Pumps Ltd
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Filing: 1972-08-21
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Granted: 1974-02-19
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Expires: 1992-08-21
Abstract
Abstract A rotary-shaft liquid handling machine, for example a centrifugal pump, includes a rotary shaft extending through an opening in a wall of the machine casing, and an annular seal is provided between the shaft and the casing wall to close the opening and has rotor and stator portions on the shaft and casing wall respectively, which portions define an annular clearance. The clearance is comprised by an intermediate chamber and inlet and outlet ducts to and from the chamber, the arrangement being such that pressurized leakage fluid flows through the inlet duct to the chamber wherein the liquid vapourises and expands to inhibit leakage flow through the inlet duct.
Inventors
- 👤 F Randell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 05:04
CPC Classifications
F; F16; F16J; F16J15/00; F16J15/16; F16J15/40; F04; F04D; F04D29/00; F04D29/08; F04D29/10; F04D29/106; F04D29/108; F22; F22D; F22D11/00; F22D11/02
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
207 words
A rotodynamic pump including a pump casing: a rotary shaft extending through an opening in a wall of the casing, an impeller mounted on the shaft, an inlet to the casing for feed liquid and a discharge from the casing for pumped liquid, and an annular seal between the shaft and the casing wall to close the opening; the annular seal comprising rotor and stator portions on respectively the shaft and the casing wall and defining between them a labyrinth of axially extending annular ducts alternating with radially extending annular chambers, the axial ducts having a fixed clearance and a first of said axial ducts constituting an inlet duct while a final axial duct of the labyrinth constitutes a fluid discharge duct; the labyrinth arrangement being such that a net radial fluid flow is provided therethrough; radial and axial passages in the casing for the passage of hot pressurised leakage liquid from the pump impeller to the axial inlet duct of the labyrinth whereby the hot leakage liquid passing through labyrinth vapourises in at least the final chamber of the labyrinth, due to reduction in pressure below the saturation value in the chamber, and vapour flows through the discharge duct to inhibit leakage flow through the labyrinth.
Claim 2
Dependent Claim
207 words
A rotodynamic pump including a pump casing: a rotary shaft extending through an opening in a wall of the casing, an impeller mounted on the shaft, an inlet to the casing for feed liquid and a discharge from the casing for pumped liquid, and an annular seal between the shaft and the casing wall to close the opening; the annular seal comprising rotor and stator portions on respectively the shaft and the casing wall and defining between them a labyrinth of axially extending annular ducts alternating with radially extending annular chambers, the axial ducts having a fixed clearance and a first of said axial ducts constituting an inlet duct while a final axial duct of the labyrinth constitutes a fluid discharge duct; the labyrinth arrangement being such that a net radial fluid flow is provided therethrough; radial and axial passages in the casing for the passage of hot pressurised leakage liquid from the pump impeller to the axial inlet duct of the labyrinth whereby the hot leakage liquid passing through labyrinth vapourises in at least the final chamber of the labyrinth, due to reduction in pressure below the saturation value in the chamber, and vapour flows through the discharge duct to inhibit leakage flow through the labyrinth.
Claim 3
Dependent Claim
18 words
The seal according to claim 1, wherein the labyrinth is arranged for net radially inward flow of fluid.
Claim 4
Dependent Claim
18 words
The seal according to claim 1, wherein the labyrinth is arranged for net radially outward flow of fluid.
Claim 5
Dependent Claim
22 words
The seal according to claim 1, wherein the labyrinth is defined by axially extending interleaved formations on the rotor and stator portions.
Claim 6
Dependent Claim
180 words
A centrifugal pump including a rotary impeller, an impeller casing, a drive shaft supporting the impeller and extending through an opening in a wall of the casing, a seal arrangement comprising a first fluid sealing device between the impeller and the casing and a second fluid sealing device spaced from the first and comprising rotor and stator portions on respectively the shaft and the casing wall and defining between them an annular clearance to permit leakage flow of pressurised liquid from the casing: said clearance including inlet and outlet annular ducts and an intermediate annular chamber communicating with the ducts whereby leakage liquid vapourises on discharge from the inlet duct into the chamber, the vapour formed on the chamber expands to inhibit leakage flow through the inlet duct, and vapour flows from the chamber through the outlet duct, and a fluid chamber located between the first and second sealing devices to receive fluid from the first sealing device and pass same to the second sealing device, and, means to maintain the fluid in the fluid chamber at pump suction pressure.
Claim 7
Dependent Claim
180 words
A centrifugal pump including a rotary impeller, an impeller casing, a drive shaft supporting the impeller and extending through an opening in a wall of the casing, a seal arrangement comprising a first fluid sealing device between the impeller and the casing and a second fluid sealing device spaced from the first and comprising rotor and stator portions on respectively the shaft and the casing wall and defining between them an annular clearance to permit leakage flow of pressurised liquid from the casing: said clearance including inlet and outlet annular ducts and an intermediate annular chamber communicating with the ducts whereby leakage liquid vapourises on discharge from the inlet duct into the chamber, the vapour formed on the chamber expands to inhibit leakage flow through the inlet duct, and vapour flows from the chamber through the outlet duct, and a fluid chamber located between the first and second sealing devices to receive fluid from the first sealing device and pass same to the second sealing device, and, means to maintain the fluid in the fluid chamber at pump suction pressure.
Claim 8
Dependent Claim
24 words
The pump according to claim 5, including a fluid discharge chamber for receiving fluid discharge from the discharge duct of the second sealing device.
Claim 9
Dependent Claim
78 words
The pump according to claim 5, wherein the clearance of the second sealing device is a labyrinth, defined by axially extending interleaved formations on the rotor and stator portions and composed of axial ducts alternating with radial chambers whereby vapourisation occurs in at least the final chamber of the labyrinth and vapour flows through the annular outlet duct of the labyrinth to inhibit leakage flow through the labyrinth, the labyrinth being arranged for net radial fluid flow therethrough.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-18 | 1977-08-20 | 1978-02-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-18 | 1981-08-20 | 1982-02-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-18 | 1985-08-20 | 1986-02-19 | $7700.00 | Window Closed / Lapsed |