F15B 21/04
Special measures taken in connection with the properties of the fluid
F15B21/04 (Special measures taken in connection with the properties of the fluid) appears on 976 US grants and 972 published applications in this corpus.
Search patents in F15B- Granted patents
- 976
- Published applications
- 972
- Assignees
- 515
- Inventors
- 2,199
- Latest grant
- 6 Oct 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 10 | 0 |
| 1977 | 10 | 0 |
| 1978 | 3 | 0 |
| 1979 | 3 | 0 |
| 1980 | 7 | 0 |
| 1981 | 4 | 0 |
| 1982 | 9 | 0 |
| 1983 | 4 | 0 |
| 1984 | 5 | 0 |
| 1985 | 6 | 0 |
| 1986 | 1 | 0 |
| 1987 | 6 | 0 |
| 1988 | 2 | 0 |
| 1989 | 5 | 0 |
| 1990 | 2 | 0 |
| 1991 | 4 | 0 |
| 1992 | 4 | 0 |
| 1993 | 7 | 0 |
| 1994 | 8 | 0 |
| 1995 | 8 | 0 |
| 1996 | 7 | 0 |
| 1997 | 7 | 0 |
| 1998 | 16 | 0 |
| 1999 | 10 | 0 |
| 2000 | 12 | 0 |
| 2001 | 21 | 3 |
| 2002 | 18 | 15 |
| 2003 | 26 | 24 |
| 2004 | 15 | 29 |
| 2005 | 19 | 23 |
| 2006 | 13 | 21 |
| 2007 | 16 | 21 |
| 2008 | 10 | 19 |
| 2009 | 8 | 22 |
| 2010 | 16 | 25 |
| 2011 | 12 | 26 |
| 2012 | 20 | 21 |
| 2013 | 19 | 37 |
| 2014 | 27 | 39 |
| 2015 | 34 | 42 |
| 2016 | 26 | 33 |
| 2017 | 34 | 45 |
| 2018 | 29 | 60 |
| 2019 | 57 | 72 |
| 2020 | 72 | 63 |
| 2021 | 69 | 68 |
| 2022 | 66 | 62 |
| 2023 | 48 | 51 |
| 2024 | 43 | 54 |
| 2025 | 61 | 55 |
| 2026 | 37 | 42 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Subgroups
Granted patents
- F15B 21/042Controlling the temperature of the fluid268
- F15B 21/041Removal or measurement of solid or liquid contamination256
- F15B 21/044Removal or measurement of undissolved gas215
- F15B 21/045Compensating for variations in viscosity or temperature120
- F15B 21/048Arrangements for compressed air preparation103
- F15B 21/047Preventing foaming, churning or cavitation79
Recent patents
- Foreign object recognition system6 Oct 2026US 12,755,537 B2Komatsu Ltd.
- Transportation vehicle22 Sep 2026US 12,742,411 B2Hitachi Construction Machinery Co., Ltd.
- Small displacement hydraulic actuator22 Sep 2026US 12,742,464 B2Zhejiang Kc Mechanical & Electrical Co., Ltd.
- Hydraulic system with cooling circuit and machine tool8 Sep 2026US 12,729,701 B2HAWE Hydraulik SE
- System, method, apparatus, device and kit for containing oil during a hydraulic purge1 Sep 2026US 12,723,606 B2
- Actuator unit, system and operating method8 Oct 2026US 2026/0309170 A1Knorr-Bremse Systeme fur Nutzfahrzeuge GmbH
- System and method for deaeration1 Oct 2026US 2026/0295469 A1Donaldson Company, Inc.
- Mechanism for online continuous purification of hydraulic and/or lubricating oil using available system pressure24 Sep 2026US 2026/0286991 A1
- Pneumatic automation device, maintenance assembly, pneumatic system, and method17 Sep 2026US 2026/0276012 A1Festo AG & Co.
- Construction Machine3 Sep 2026US 2026/0257547 A1Putzmeister Engineering GmbH
Most cited
By later US patents
- Bleed valve for bleeding fluid from a hydraulic circuit105US 5,853,071 AMcDonnell Douglas Corporation · 1998
- Hydraulic circuit for synchronized horizontal extension of cylinders86US 7,926,410 B2JR Automation Technologies, LLC · 2011
- Pressure exchanger with an anti-cavitation pressure relief system in the end covers70US 6,540,487 B2Energy Recovery, Inc. · 2003
- Compressed air control apparatus63US 5,600,953 AAisin Seiki Kabushiki Kaisha · 1997
- Hydraulic tensioner50US 6,383,103 B1Tsubakimoto Chain Co. · 2002