Patent US4373868A successfully refreshed from Google Patents.
US4373868A
Expired / Lapsed
US
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Diffusion pump for leak detector
Assignee: Varian Medical Systems Inc
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Filing: 1978-01-17
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Granted: 1983-02-15
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Expires: 1998-01-17
Abstract
Abstract A diffusion pump for a leak detector of helium or other light gases includes a foreline, responsive to gases from vacuum equipment being monitored for leak detection, and an inlet, connected to a mass spectrometer or other similar high vacuum gas measuring instrument. The diffusion pump includes two diffusion stages. The second stage has a diffuser throat with a relatively narrow width and small cross-sectional area so that the velocity of diffusion oil vapor flowing through it causes the light gases to be easily back diffused from the foreline to the inlet, while substantially preventing the flow of air or other relatively heavy gases between the foreline and the inlet. Fluid is returned to the pool by a conduit having a vertically extending, longitudinal axis aligned substantially with the center of the pool and an outlet orifice in proximity to the bottom of the pool, whereby the oil is returned to the coolest part of the pool at its bottom, central portion.
Inventors
- 👤 Arthur A. Landfors
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 14:47
CPC Classifications
F; F04; F04F; F04F9/00
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
173 words
A diffusion pump comprising a body assembly including a cool wall having a longitudinal, centrally located axis, a cylindrical heater for establishing a cylindrical radial thermal gradient, said heater comprising a heating wall coaxial with the body assembly and surrounding a pool of liquid that the heater causes to boil changing its state to vapor, a jet assembly coaxial with the body assembly, means for providing a flow path for the vapor from the surface of the pool to the jet assembly, the jet assembly inducing at least one annular nozzle concentric with the axis for directing the vapor downwardly against the cool wall, the cool wall condensing the vapor striking it into a liquid that flows downwardly along the body assembly toward the pool, and means for providing a flow path for the condensed liquid directly from the body assembly to a region substantially at the bottom of the pool and on the axis so that the condensed liquid flows outwardly and upwardly from the bottom of the pool and the axis.
Claim 2
Dependent Claim
173 words
A diffusion pump comprising a body assembly including a cool wall having a longitudinal, centrally located axis, a cylindrical heater for establishing a cylindrical radial thermal gradient, said heater comprising a heating wall coaxial with the body assembly and surrounding a pool of liquid that the heater causes to boil changing its state to vapor, a jet assembly coaxial with the body assembly, means for providing a flow path for the vapor from the surface of the pool to the jet assembly, the jet assembly inducing at least one annular nozzle concentric with the axis for directing the vapor downwardly against the cool wall, the cool wall condensing the vapor striking it into a liquid that flows downwardly along the body assembly toward the pool, and means for providing a flow path for the condensed liquid directly from the body assembly to a region substantially at the bottom of the pool and on the axis so that the condensed liquid flows outwardly and upwardly from the bottom of the pool and the axis.
Claim 3
Dependent Claim
27 words
The pump of claim 1 wherein the jet assembly is mounted above the heating wall for the pool to be substantially thermally isolated from the heating wall.
Claim 4
Dependent Claim
101 words
The pump of claim 1 wherein the jet assembly and body assembly are mounted on a shelf above the heating wall for the pool to form an annular reservoir for the downwardly flowing liquid, the reservoir being thermally isolated from the heating wall for the pool, the flow path providing means for the liquid including a return tube extending downwardly from the reservoir toward the on axis region for providing a flow path for overflow liquid in the reservoir, said return tube having an orifice submerged in the pool in proximity to the bottom of the pool, and on the axis.
Claim 5
Dependent Claim
19 words
The pump of claim 3 wherein the pool is located in a pool reservoir having a relatively flat bottom.
Claim 6
Dependent Claim
19 words
The pump of claim 1 wherein the pool is located in a pool reservoir having a relatively flat bottom.
Claim 7
Dependent Claim
34 words
The pump of claim 5 wherein the flow path providing means includes a return tube having an orifice submerged in the pool in proximity to the bottom of the pool, and on the axis.
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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) | 1986-02-14 | 1986-08-16 | 1987-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-02-14 | 1990-08-16 | 1991-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-02-14 | 1994-08-16 | 1995-02-15 | $7700.00 | Window Closed / Lapsed |