Patent US4920531A successfully refreshed from Google Patents.
US2575325A
Expired / Lapsed
US
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Heat pump system
Assignee: AMERICAN GAS AND ELECTRIC Co
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Filing: 1948-02-14
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Granted: 1951-11-20
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Expires: 1968-02-14
Abstract
No abstract record available.
Inventors
- 👤 Ambrose Eugene Russell
- 👤 Sporn Philip
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 04:14
CPC Classifications
F; F24; F24D; F24D17/00; F24D17/0005; F24D17/001; F24D17/02; F25; F25B; F25B30/00; F25B30/02; F25B5/00; F25B5/02; Y; Y02; Y02B; Y02B30/00; Y02B30/18; Y02B30/52
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
FR487762A
Cited
US1874803A
Cited
US1935281A
Cited
US2042812A
Cited
US2162245A
Cited
US2375157A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1954-11-19 | 1955-05-21 | 1955-11-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1958-11-19 | 1959-05-21 | 1959-11-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1962-11-19 | 1963-05-21 | 1963-11-20 | $7700.00 | Window Closed / Lapsed |