H01F 27/14
Expansion chambers
Official title: Expansion chambers; Oil conservators; Gas cushions; Arrangements for purifying, drying, or filling
H01F27/14 (Expansion chambers) appears on 170 US grants and 168 published applications in this corpus.
Search patents in H01F- Granted patents
- 170
- Published applications
- 168
- Assignees
- 93
- Inventors
- 392
- Latest grant
- 15 Sep 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 1 | 0 |
| 1977 | 0 | 0 |
| 1978 | 1 | 0 |
| 1979 | 0 | 0 |
| 1980 | 0 | 0 |
| 1981 | 1 | 0 |
| 1982 | 1 | 0 |
| 1983 | 0 | 0 |
| 1984 | 2 | 0 |
| 1985 | 3 | 0 |
| 1986 | 1 | 0 |
| 1987 | 4 | 0 |
| 1988 | 3 | 0 |
| 1989 | 3 | 0 |
| 1990 | 1 | 0 |
| 1991 | 1 | 0 |
| 1992 | 3 | 0 |
| 1993 | 2 | 0 |
| 1994 | 1 | 0 |
| 1995 | 1 | 0 |
| 1996 | 0 | 0 |
| 1997 | 1 | 0 |
| 1998 | 3 | 0 |
| 1999 | 4 | 0 |
| 2000 | 2 | 0 |
| 2001 | 2 | 0 |
| 2002 | 2 | 4 |
| 2003 | 5 | 3 |
| 2004 | 5 | 5 |
| 2005 | 2 | 6 |
| 2006 | 2 | 3 |
| 2007 | 3 | 4 |
| 2008 | 4 | 11 |
| 2009 | 3 | 3 |
| 2010 | 7 | 8 |
| 2011 | 7 | 14 |
| 2012 | 6 | 7 |
| 2013 | 5 | 5 |
| 2014 | 8 | 5 |
| 2015 | 6 | 10 |
| 2016 | 2 | 7 |
| 2017 | 9 | 8 |
| 2018 | 5 | 4 |
| 2019 | 4 | 9 |
| 2020 | 5 | 4 |
| 2021 | 8 | 10 |
| 2022 | 7 | 6 |
| 2023 | 6 | 10 |
| 2024 | 4 | 8 |
| 2025 | 8 | 8 |
| 2026 | 6 | 6 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Recent patents
- Intelligent drying device for transformer15 Sep 2026US 12,734,478 B2Fortune Electric Co., Ltd.
- Subsea control and power enclosure9 Jun 2026US 12,651,688 B2Siemens Energy, Inc.
- Technologies for preventing the explosion of electrical transformers9 Jun 2026US 12,651,698 B2Philippe Magnier LLC
- Apparatus and method for predicting transformer state in consideration of whether oil filtering is performed5 May 2026US 12,619,904 B2Onepredict Co., Ltd.
- Method and system for breather health assessment for a transformer breather10 Mar 2026US 12,571,671 B2Hitachi Energy Ltd
- Air-cell rupture diagnosis method and system24 Sep 2026US 2026/0290683 A1Fortune Electric Co., Ltd.
- Cooling arrangement and method for cooling at least one oil-to-air external heat exchanger6 Aug 2026US 2026/0227131 A1Hitachi Energy Ltd
- Transformer Pad with Secondary Containment for Transformer Oil11 Jun 2026US 2026/0162869 A1Dominion Energy, Inc.
- System including a transformer30 Apr 2026US 2026/0120936 A1Hitachi Energy Ltd
- A cooling arrangement for cooling a transformer30 Apr 2026US 2026/0120937 A1Hitachi Energy Ltd
Most cited
By later US patents
- Process for the extraction of oil or polychlorinated biphenyl from electrical parts through the use of solvents and for distillation of the solvents49US 4,879,004 AMicafil AG · 1989
- Apparatus for continually upgrading transformer dielectric liquid46US 4,437,082 AWestinghouse Electric Corp. · 1984
- Hermetically sealed, non-venting electrical apparatus with dielectric fluid having defined chemical composition45US 5,736,915 ACooper Industries, Inc. · 1998
- Food grade vegetable oil based dielectric fluid and methods of using same42US 6,398,986 B1Cooper Industries, Inc. · 2002
- Process for removing undesirable substances from electrical devices38US 4,425,949 ADiamond Shamrock Corporation · 1984