Patent US4367624A successfully refreshed from Google Patents.
US4367624A
Expired / Lapsed
US
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Control system for hydraulic actuator
Assignee: Komatsu Ltd
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Filing: 1980-02-15
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Granted: 1983-01-11
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Expires: 2000-02-15
Abstract
Abstract A control system for a hydraulic actuator comprising a first pump with large displacement capacity, a second pump with small displacement capacity, a pilot pump, a first pilot operated spring centered control valve connected at the input side thereof to the first pump, the output side of which is selectively connected to the hydraulic actuator and drain, a second pilot operated spring centered control valve connected at the input side thereof to the second pump, the output side of which is selectively connected to the hydraulic actuator and drain, and a third control valve for pilot pressure connected at the input side thereof to the pilot pump, the output side of which is connected to the first and second control valves wherein the second control valve is adapted to be actuated by a pilot pressure lower than a pilot pressure which actuates the first control valve.
Inventors
- 👤 Yasuhiro Ogata
- 👤 Norishige Mutou
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 20:37
CPC Classifications
E; E02; E02F; E02F9/00; E02F9/20; E02F9/22; E02F9/2278; E02F9/2285; E02F3/00; E02F3/04; E02F3/76; E02F3/80; E02F3/84; E02F3/844; E02F9/2221; E02F9/2239; E02F9/2292; F; F15; F15B; F15B11/00; F15B11/16; F15B11/17; F15B2211/00; F15B2211/20; F15B2211/205; F15B2211/20576; F15B2211/20584; F15B2211/30; F15B2211/305; F15B2211/3056; F15B2211/30585; F15B2211/31; F15B2211/3105; F15B2211/3116; F15B2211/32; F15B2211/329; F15B2211/60; F15B2211/635; F15B2211/6355; F15B2211/67; F15B2211/70; F15B2211/71; F15B2211/7114; F15B2211/7128; F15B2211/7142
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
337 words
A control system for controlling a hydraulic actuator during full stroke operations and inching operations, said control system comprising: an engine; a first hydraulic pump with a large displacement capacity driven by said engine; a second hydraulic pump with a small displacement capacity driven by said engine; a pilot pump driven by said engine; first pilot operated control valve means connected at the input side thereof to said first pump, the output side thereof being selectively connected to said hydraulic actuator and a drain; second pilot operated control valve means connected at the input side thereof to said second pump, the output side thereof being selectively connected to said hydraulic actuator and a drain wherein said second pilot operated control valve means is actuated by a lower pilot pressure than said first pilot operated control valve means; and third control valve means for pilot pressure connected at the input side thereof to said pilot pump, the output side thereof being connected to said first and second pilot operated control valve means for controlling the actuation thereof, such that, during full stroke operations, said first and second pilot operated control valve means are actuated by said third control valve means such that said hydraulic actuator is operated by hydraulic fluid from said first and second hydraulic pumps and during inching operations, only said second pilot operated control valve means is operated by said third control valve means such that said hydraulic actuator is operated by hydraulic fluid from only said second hydraulic pump, wherein each of said first and second pilot operated control valve means has two pilot ports formed therein one of which is connected to said third control valve means for pilot pressure through a first conduit, the other port being connected to said third control valve means for pilot pressure through a second conduit and wherein adjustable restrictor means is provided between said first and second conduits, said restrictor means being interlocked with lever means for operating said third control valve means for pilot pressure.
Claim 2
Dependent Claim
337 words
A control system for controlling a hydraulic actuator during full stroke operations and inching operations, said control system comprising: an engine; a first hydraulic pump with a large displacement capacity driven by said engine; a second hydraulic pump with a small displacement capacity driven by said engine; a pilot pump driven by said engine; first pilot operated control valve means connected at the input side thereof to said first pump, the output side thereof being selectively connected to said hydraulic actuator and a drain; second pilot operated control valve means connected at the input side thereof to said second pump, the output side thereof being selectively connected to said hydraulic actuator and a drain wherein said second pilot operated control valve means is actuated by a lower pilot pressure than said first pilot operated control valve means; and third control valve means for pilot pressure connected at the input side thereof to said pilot pump, the output side thereof being connected to said first and second pilot operated control valve means for controlling the actuation thereof, such that, during full stroke operations, said first and second pilot operated control valve means are actuated by said third control valve means such that said hydraulic actuator is operated by hydraulic fluid from said first and second hydraulic pumps and during inching operations, only said second pilot operated control valve means is operated by said third control valve means such that said hydraulic actuator is operated by hydraulic fluid from only said second hydraulic pump, wherein each of said first and second pilot operated control valve means has two pilot ports formed therein one of which is connected to said third control valve means for pilot pressure through a first conduit, the other port being connected to said third control valve means for pilot pressure through a second conduit and wherein adjustable restrictor means is provided between said first and second conduits, said restrictor means being interlocked with lever means for operating said third control valve means for pilot pressure.
Claim 3
Dependent Claim
49 words
A control system for a hydraulic actuator as recited in claim 1 wherein said first pilot operated control valve means is spring centered type and has four positions formed therein and said second pilot operated control valve means is also spring centered type and has three positions formed therein.
Claim 4
Dependent Claim
78 words
A control system for a hydraulic actuator as recited in claim 1 further comprising another hydraulic actuator; fourth pilot operated control valve means connected at the input side thereof to said second pump, the output side thereof being selectively connected to said another actuator and drain; and fifth control valve means for pilot pressure connected at the input side thereof to said pilot pump, the output side thereof being connected to said fourth pilot operated control valve means.
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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) | 1986-01-10 | 1986-07-12 | 1987-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-01-10 | 1990-07-12 | 1991-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-01-10 | 1994-07-12 | 1995-01-11 | $7700.00 | Window Closed / Lapsed |