Patent US3264084A successfully refreshed from Google Patents.
Patent US3579986A successfully refreshed from Google Patents.
US3579986A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for controlling pumps for operating hydraulic motors equipment
Assignee: Hitachi Ltd
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Filing: 1969-06-06
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Granted: 1971-05-25
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Expires: 1989-06-06
Abstract
Abstract A device for controlling pumps for operating hydraulic motors comprising at least two variable displacement pumps, valve means for each said pump disposed between the discharge side of the pump and the hydraulic motors for switching a charge of hydraulic fluid delivered to the hydraulic motors upon operation of an operating lever, and a hydraulic servomechanism for each said pump operated by a control lever coupled to said operation lever for moving a discharge flow control member of the pump, said servomechanism having a control circuit including a first control valve operated by said control lever for forming a flow of hydraulic fluid therethrough to move said discharge flow control member of the pump to a position corresponding to the amount of operation of the control lever, and a second control valve responding to the discharge pressure of the pump for forming another flow of hydraulic fluid therethrough to move said discharge flow control member of the pump to a position corresponding to the discharge pressure of the pump.
Inventors
- 👤 Katsuro Abe
- 👤 Saburo Kakinuma
- 👤 Masaaki Uno
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 19:44
CPC Classifications
E; E02; E02F; E02F9/00; E02F9/20; E02F9/22; E02F9/2264; E02F9/2267; E02F9/2004; E02F9/2271; E02F9/2278; E02F9/2296; F; F15; F15B; F15B11/00; F15B11/16; F15B11/17; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/42; F16H61/437; F16H61/44; F16H61/448; F15B2211/00; F15B2211/20; F15B2211/205; F15B2211/2053; F15B2211/20546; F15B2211/20576; F15B2211/26; F15B2211/265; F15B2211/2656; F15B2211/30; F15B2211/305; F15B2211/30525; F15B2211/315; F15B2211/31523; F15B2211/31541; F15B2211/32; F15B2211/321; F15B2211/324
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
391 words
A device for controlling pumps for operating hydraulic motors comprising at least two variable displacement pumps operated by a single prime mover, valve means for each said pump disposed between the discharge side of the pump and the hydraulic motors for switching a charge of hydraulic fluid delivered to the hydraulic motors upon operation of an operation lever, and a hydraulic servomechanism for each said pump operated by a control lever coupled to said operation lever for moving a discharge flow control member of the pump, said operation lever for said valve means and said control lever for said hydraulic servomechanism being operatively connected to each other such that when the former is in its maximum stroke position the latter is in a position in which the discharge flow of the pump is maximized and when the former is in its neutral position the latter is in a position in which the discharge flow of the pump is minimized, said hydraulic servomechanism having a control circuit including a first control valve operated by said control lever for forming a flow of hydraulic fluid therethrough to move said discharge, flow control member of the pump to a position corresponding to the amount of operation of the control lever, and a second control valve responding to the discharge pressure of the pump for forming another flow of hydraulic fluid therethrough to move said discharge flow control member of the pump to a position corresponding to the discharge pressure of the pump, said first control valve including a movable member operatively connected to said control member of the pump for stopping said flow of hydraulic fluid when said control member has been moved to said position corresponding to the amount of operation of said control lever, said second control valve including a movable member operatively connected to said control member of the pump for stopping said other flow of hydraulic fluid when said control member has been moved to said position corresponding to the discharge pressure of the pump, said movable member of said second control valve being operatively connected to said movable member of said first control valve such that the second control valve controls the discharge pressure of the pump in a range of the discharge flow of the pump below the maximum discharge flow as determined by the first control valve.
Claim 2
Independent Claim
391 words
A device for controlling pumps for operating hydraulic motors comprising at least two variable displacement pumps operated by a single prime mover, valve means for each said pump disposed between the discharge side of the pump and the hydraulic motors for switching a charge of hydraulic fluid delivered to the hydraulic motors upon operation of an operation lever, and a hydraulic servomechanism for each said pump operated by a control lever coupled to said operation lever for moving a discharge flow control member of the pump, said operation lever for said valve means and said control lever for said hydraulic servomechanism being operatively connected to each other such that when the former is in its maximum stroke position the latter is in a position in which the discharge flow of the pump is maximized and when the former is in its neutral position the latter is in a position in which the discharge flow of the pump is minimized, said hydraulic servomechanism having a control circuit including a first control valve operated by said control lever for forming a flow of hydraulic fluid therethrough to move said discharge, flow control member of the pump to a position corresponding to the amount of operation of the control lever, and a second control valve responding to the discharge pressure of the pump for forming another flow of hydraulic fluid therethrough to move said discharge flow control member of the pump to a position corresponding to the discharge pressure of the pump, said first control valve including a movable member operatively connected to said control member of the pump for stopping said flow of hydraulic fluid when said control member has been moved to said position corresponding to the amount of operation of said control lever, said second control valve including a movable member operatively connected to said control member of the pump for stopping said other flow of hydraulic fluid when said control member has been moved to said position corresponding to the discharge pressure of the pump, said movable member of said second control valve being operatively connected to said movable member of said first control valve such that the second control valve controls the discharge pressure of the pump in a range of the discharge flow of the pump below the maximum discharge flow as determined by the first control valve.
Claim 3
Dependent Claim
61 words
A device for controlling pumps as defined in claim 1 in which said hydraulic servomechanism includes a servo piston controlled by said control circuit for moving said discharge flow control member of the pump, said movable member of said first control valve and said movable member of said second control valve being connected to said servo piston through a follower lever.
Claim 4
Dependent Claim
168 words
A device for controlling pumps as defined in claim 2 in which said first control valve comprises a rotary valve element having valve passages and operated by said control lever, said movable member of the first control valve consists of a rotary sleeve enclosing said rotary valve element to rotate relative to the same and having ports adapted to open and close said valve passages, said second control valve comprises a valve spool urged by a spring at one end therEof and subjected to the discharge pressure of the pump at the other end, said movable member of the second control valve consists of a movable sleeve enclosing said valve spool for axial sliding motion relative to the same for opening and closing valve passages of the second control valve, and said follower lever is connected to said rotary sleeve to turn about the axis of said rotary sleeve and pivotally connected to said servo piston at one end and to said movable sleeve at the other end.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-05-24 | 1974-11-23 | 1975-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-24 | 1978-11-23 | 1979-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-24 | 1982-11-23 | 1983-05-25 | $7700.00 | Window Closed / Lapsed |