F15B 21/00
Common features of fluid actuator systems
Official title: Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
F15B21/00 (Common features of fluid actuator systems) appears on 3,059 US grants and 3,010 published applications in this corpus.
Search patents in F15B- Granted patents
- 3,059
- Published applications
- 3,010
- Assignees
- 1,257
- Inventors
- 5,809
- Latest grant
- 6 Oct 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 25 | 0 |
| 1977 | 18 | 0 |
| 1978 | 12 | 0 |
| 1979 | 8 | 0 |
| 1980 | 16 | 0 |
| 1981 | 7 | 0 |
| 1982 | 14 | 0 |
| 1983 | 10 | 0 |
| 1984 | 17 | 0 |
| 1985 | 19 | 0 |
| 1986 | 10 | 0 |
| 1987 | 20 | 0 |
| 1988 | 16 | 0 |
| 1989 | 17 | 0 |
| 1990 | 7 | 0 |
| 1991 | 14 | 0 |
| 1992 | 17 | 0 |
| 1993 | 18 | 0 |
| 1994 | 21 | 0 |
| 1995 | 22 | 0 |
| 1996 | 30 | 0 |
| 1997 | 26 | 0 |
| 1998 | 36 | 0 |
| 1999 | 39 | 0 |
| 2000 | 36 | 0 |
| 2001 | 56 | 11 |
| 2002 | 58 | 46 |
| 2003 | 55 | 77 |
| 2004 | 65 | 72 |
| 2005 | 62 | 80 |
| 2006 | 54 | 76 |
| 2007 | 56 | 76 |
| 2008 | 49 | 77 |
| 2009 | 44 | 85 |
| 2010 | 39 | 86 |
| 2011 | 55 | 81 |
| 2012 | 67 | 75 |
| 2013 | 75 | 122 |
| 2014 | 87 | 139 |
| 2015 | 94 | 155 |
| 2016 | 114 | 128 |
| 2017 | 121 | 135 |
| 2018 | 124 | 188 |
| 2019 | 168 | 191 |
| 2020 | 203 | 191 |
| 2021 | 189 | 188 |
| 2022 | 187 | 185 |
| 2023 | 152 | 169 |
| 2024 | 154 | 149 |
| 2025 | 168 | 137 |
| 2026 | 88 | 91 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Subgroups
Granted patents
- F15B 21/04Special measures taken in connection with the properties of the fluid976
- F15B 21/08Servomotor systems incorporating electrically operated control means877
- F15B 21/14Energy-recuperation means566
- F15B 21/008Reduction of noise or vibration205
- F15B 21/06Use of special fluids153
- F15B 21/12Fluid oscillators or pulse generators117
- F15B 21/005Filling or draining of fluid systems116
- F15B 21/02Servomotor systems with program control derived from a store or timing device85
Recent patents
- System for returning fluid from hydraulic devices of work machines6 Oct 2026US 12,753,579 B2Caterpillar Inc.
- Control method based on a four-chamber hydraulic cylinder6 Oct 2026US 12,753,780 B2Taiyuan University of Technology
- 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.
- 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.
- Hydraulic system for a refuse vehicle1 Oct 2026US 2026/0296342 A1Oshkosh Corporation
- Mechanism for online continuous purification of hydraulic and/or lubricating oil using available system pressure24 Sep 2026US 2026/0286991 A1
- Brake apparatus for vehicles17 Sep 2026US 2026/0274233 A1Hyundai Mobis Co., Ltd.
Most cited
By later US patents
- Hydraulic circuit and control system therefor115US 5,138,838 ACaterpillar Inc. · 1992
- Bleed valve for bleeding fluid from a hydraulic circuit105US 5,853,071 AMcDonnell Douglas Corporation · 1998
- Adjustable magneto-rheological fluid device103US 5,956,951 AMR Technologies · 1999
- Systems and methods for energy storage and recovery using compressed gas96US 7,832,207 B2SustainX, Inc. · 2010
- Downhole actuation system utilizing electroactive fluids95US 6,568,470 B2Baker Hughes Incorporated · 2003