Patent US2659173A successfully refreshed from Google Patents.
Patent US3913339A successfully refreshed from Google Patents.
US3913339A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reduction in cooldown time for cryogenic refrigerator
Assignee: Raytheon Co
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Filing: 1974-03-04
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Granted: 1975-10-21
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Expires: 1994-03-04
Abstract
Abstract Cryogenic refrigerator with a free piston displacer has an adjustable stop to control its stroke. Longer strokes during higher temperature operation produce faster cooldown rate and, as the design temperature is approached, the stop is adjusted to limit stroke to a value consistent with optimum refrigeration at design temperature.
Inventors
- 👤 Robert L Berry
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 23:37
CPC Classifications
F; F02; F02G; F02G1/00; F02G1/04; F02G1/043; F02G1/044; F02G1/0445; F02G2250/00; F02G2250/18
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
193 words
An expander for a cryogenic refrigerator, said expander comprising: an expander cylinder, a displacer type piston in said expander cylinder for dividing said expander cylinder into an expansion volume and compression volume, the area of said piston defining said expansion volume being greater than the area of said piston defining said compression volume, said expansion volume being the cold expansion volume which produces refrigeration upon gas expansion, a regenerator connected between such expansion and compression volumes, means for connecting a source of pulsating refrigerant gas to all said volumes, and means for urging said piston in a direction to first reduce said expansion volume, and increase said compression volume, and second to increase said expansion volume and reduce said compression volume, the improvement comprising: an adjustable mechanical stop positioned to limit the stroke of said expander piston, said adjustable stop having means for controlling mechanical stop relative position between said expander cylinder and said expander piston so that said stop can be adjusted for a larger stroke of said expander piston during cooldown and to limit motion of said expander piston to a shorter stroke when said expander is operating near design temperature.
Claim 2
Dependent Claim
193 words
An expander for a cryogenic refrigerator, said expander comprising: an expander cylinder, a displacer type piston in said expander cylinder for dividing said expander cylinder into an expansion volume and compression volume, the area of said piston defining said expansion volume being greater than the area of said piston defining said compression volume, said expansion volume being the cold expansion volume which produces refrigeration upon gas expansion, a regenerator connected between such expansion and compression volumes, means for connecting a source of pulsating refrigerant gas to all said volumes, and means for urging said piston in a direction to first reduce said expansion volume, and increase said compression volume, and second to increase said expansion volume and reduce said compression volume, the improvement comprising: an adjustable mechanical stop positioned to limit the stroke of said expander piston, said adjustable stop having means for controlling mechanical stop relative position between said expander cylinder and said expander piston so that said stop can be adjusted for a larger stroke of said expander piston during cooldown and to limit motion of said expander piston to a shorter stroke when said expander is operating near design temperature.
Claim 3
Dependent Claim
26 words
The expander of claim 1 wherein said adjustable stop is positioned to be directly in line with said expander piston during reciprocation of said expander piston.
Claim 4
Dependent Claim
196 words
An expander for a cryogenic refrigerator, said expander comprising: an expander cylinder, a displacer type piston in said expander cylinder for dividing said expander cylinder into an expansion volume and compression volume, the area of said piston defining said expansion volume being greater than the area of said piston defining said compression volume, said expansion volume being the cold expansion volume which produces refrigeration upon gas expansion, a regenerator connected between said expansion and compression volumes, means for connecting a source of pulsating refrigerant gas to all said volumes, and means for urging said piston in a direction to first reduce said expansion volume, and increase said compression volume, and second to increase said expansion volume and reduce said compression volume, the improvement comprising: an adjustable stop having a stop nose having an extended position where it lies in the path of said expander piston and limits the stroke of said expander piston and a retracted position at which said expander piston has a greater stroke so that said stop can be adjusted for a larger stroke of said expander piston during cooldown and for a shorter stroke when said expander is operating near design temperature.
Claim 5
Dependent Claim
196 words
An expander for a cryogenic refrigerator, said expander comprising: an expander cylinder, a displacer type piston in said expander cylinder for dividing said expander cylinder into an expansion volume and compression volume, the area of said piston defining said expansion volume being greater than the area of said piston defining said compression volume, said expansion volume being the cold expansion volume which produces refrigeration upon gas expansion, a regenerator connected between said expansion and compression volumes, means for connecting a source of pulsating refrigerant gas to all said volumes, and means for urging said piston in a direction to first reduce said expansion volume, and increase said compression volume, and second to increase said expansion volume and reduce said compression volume, the improvement comprising: an adjustable stop having a stop nose having an extended position where it lies in the path of said expander piston and limits the stroke of said expander piston and a retracted position at which said expander piston has a greater stroke so that said stop can be adjusted for a larger stroke of said expander piston during cooldown and for a shorter stroke when said expander is operating near design temperature.
Claim 6
Dependent Claim
119 words
An expander comprising: an expander cylinder, an expander displacer type piston reciprocally mounted within said expander cylinder for separating said expander cylinder into a cold first expander volume and a second compression volume, means for supplying refrigerant gas to said second expander volume, a regenerator connected between said first and second expander volumes, the improvement comprising: an adjustable mechanical stop positioned in the path of motion of said expander piston, said adjustable stop being a mechanical stop stronger than the driving forces on said expander piston to adjustably posiTively control the stroke of said expander piston so that said expander piston can have a greater expander stroke during cooldown and a lesser expander stroke when operating near cryogenic temperatures.
Claim 7
Dependent Claim
119 words
An expander comprising: an expander cylinder, an expander displacer type piston reciprocally mounted within said expander cylinder for separating said expander cylinder into a cold first expander volume and a second compression volume, means for supplying refrigerant gas to said second expander volume, a regenerator connected between said first and second expander volumes, the improvement comprising: an adjustable mechanical stop positioned in the path of motion of said expander piston, said adjustable stop being a mechanical stop stronger than the driving forces on said expander piston to adjustably posiTively control the stroke of said expander piston so that said expander piston can have a greater expander stroke during cooldown and a lesser expander stroke when operating near cryogenic temperatures.
Claim 8
Dependent Claim
26 words
The expander of claim 4 wherein said adjustable stop is positioned to be directly in line with said expander piston during reciprocation of said expander piston.
Claim 9
Dependent Claim
133 words
An expander comprising: an expander cylinder, an expander displacer type piston reciprocally mounted within said expander cylinder for separating said expander cylinder into a cold first expander volume and a second compression volume, means for supplying refrigerant gas to said second expander volume, a regenerator connected between said first and second expander volumes, the improvement comprising: an adjustable stop positioned in the path of motion of said expander piston said adjustable stop having a stop nose having an extended position where it lies in the path of said expander piston and limits the stroke of said expander piston and a retracted position at which said expander piston has a greater stroke so that said expander piston has a greater expanded stroke during cooldown and a lesser expander stroke when operating near cryogenic temperatures.
Claim 10
Dependent Claim
133 words
An expander comprising: an expander cylinder, an expander displacer type piston reciprocally mounted within said expander cylinder for separating said expander cylinder into a cold first expander volume and a second compression volume, means for supplying refrigerant gas to said second expander volume, a regenerator connected between said first and second expander volumes, the improvement comprising: an adjustable stop positioned in the path of motion of said expander piston said adjustable stop having a stop nose having an extended position where it lies in the path of said expander piston and limits the stroke of said expander piston and a retracted position at which said expander piston has a greater stroke so that said expander piston has a greater expanded stroke during cooldown and a lesser expander stroke when operating near cryogenic temperatures.
Claim 11
Independent Claim
89 words
The method of reducing cooldown time of a cryogenic expander wherein the expander has an expander cylinder and an expander displacer type piston reciprocally mounted within the expander comprising the steps of: permitting maximum stroke of the expander piston at the beginning of cooldown; and inserting a mechanical stop to limit the length of stroke of the expander piston at design temperature so that cooldown time is reduced by a greater expansion ratio at beginning of cooldown and losses are reduced at cryogenic temperature by reduced expander piston stroke.
Claim 12
Independent Claim
89 words
The method of reducing cooldown time of a cryogenic expander wherein the expander has an expander cylinder and an expander displacer type piston reciprocally mounted within the expander comprising the steps of: permitting maximum stroke of the expander piston at the beginning of cooldown; and inserting a mechanical stop to limit the length of stroke of the expander piston at design temperature so that cooldown time is reduced by a greater expansion ratio at beginning of cooldown and losses are reduced at cryogenic temperature by reduced expander piston stroke.
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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) | 1978-10-20 | 1979-04-21 | 1979-10-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-20 | 1983-04-21 | 1983-10-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-20 | 1987-04-21 | 1987-10-21 | $7700.00 | Window Closed / Lapsed |