US5218895A
Expired / Lapsed
US
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Electrohydraulic control apparatus and method
Assignee: Caterpillar Inc
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Filing: 1990-06-15
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Granted: 1993-06-15
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Expires: 2010-06-15
Abstract
Abstract An apparatus, is adapted to controllably position a movable element in a hydraulic motor. A controller receives a request signal and velocity and/or position signals from sensors. The controller, in accordance with a control scheme using velocity and/or position feedback, determines the flow of hydraulic fluid to the cylinder needed to reduce velocity and/or position errors. A directional valve, actuated by an electrohydraulic pilot system, delivers hydraulic fluid to the hydraulic motor.
Inventors
- 👤 Michael S. Lukich
- 👤 Eric A. Hutchison
- 👤 Lisa A. Obermaier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 01:43
CPC Classifications
E; E02; E02F; E02F9/00; E02F9/20; E02F9/22; E02F9/2203; E02F9/2214; F; F15; F15B; F15B21/00; F15B21/08; F15B21/087
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
147 words
An apparatus for controllably moving a movable element within a hydraulic motor in response to a flow request signal, comprising: means for delivering hydraulic fluid to said hydraulic motor in response to pilot pressure signals; means for sensing the velocity of the movable element and producing an actual velocity signal indicative of said sensed velocity; means for receiving said flow request signal and responsively producing a desired velocity signal; means for receiving said actual velocity signal and said desired velocity signal and responsively producing a velocity error signal; means for receiving said desired velocity signal and said velocity error signal, and responsively producing a flow command signal as a function of said desired velocity signal and said velocity error signal; and, means for receiving said flow command signal and responsively producing a pilot pressure signal and delivering said pilot pressure signal to said hydraulic fluid delivering means.
Claim 2
Independent Claim
147 words
An apparatus for controllably moving a movable element within a hydraulic motor in response to a flow request signal, comprising: means for delivering hydraulic fluid to said hydraulic motor in response to pilot pressure signals; means for sensing the velocity of the movable element and producing an actual velocity signal indicative of said sensed velocity; means for receiving said flow request signal and responsively producing a desired velocity signal; means for receiving said actual velocity signal and said desired velocity signal and responsively producing a velocity error signal; means for receiving said desired velocity signal and said velocity error signal, and responsively producing a flow command signal as a function of said desired velocity signal and said velocity error signal; and, means for receiving said flow command signal and responsively producing a pilot pressure signal and delivering said pilot pressure signal to said hydraulic fluid delivering means.
Claim 3
Dependent Claim
23 words
An apparatus, as set forth in claim 3, wherein said hydraulic motor is a hydraulic cylinder and said movable element is a piston.
Claim 4
Dependent Claim
20 words
An apparatus, as set forth in claim 1, wherein said pilot pressure signal is proportional to said flow command signal.
Claim 5
Dependent Claim
18 words
An apparatus, as set forth in claim 1, wherein said hydraulic fluid delivering means includes a directional valve.
Claim 6
Dependent Claim
22 words
An apparatus, as set forth in claim 4, wherein said directional valve has an extend, a neutral and a retract flow position.
Claim 7
Dependent Claim
43 words
An apparatus, as set forth in claim 1, wherein said velocity error signal producing means includes means for determining the difference between said actual velocity signal and said desired velocity signal and wherein said velocity error signal is a function of said difference.
Claim 8
Independent Claim
172 words
An apparatus for controllably positioning a movable element in a hydraulic motor in response to an position request signal, comprising: means for delivering hydraulic fluid to said hydraulic motor in response to pilot pressure signals; means for sensing the velocity of the movable element and producing an actual velocity signal indicative of said sensed position; means for sensing the velocity of the movable element and producing an actual velocity signal indicative of said sensed velocity; means for receiving said position request signal and said actual position signal and responsively producing a desired velocity signal; means for receiving said actual velocity signal and said desired velocity signals and responsively producing a velocity error signal; means for receiving said desired velocity signal and said velocity error signal, and responsively producing a flow command signal as a function of said desired velocity signal and said velocity error signal; and, means for receiving said flow command signal and responsively producing a pilot pressure signal and delivering said pilot pressure signal to said hydraulic fluid delivering means.
Claim 9
Independent Claim
172 words
An apparatus for controllably positioning a movable element in a hydraulic motor in response to an position request signal, comprising: means for delivering hydraulic fluid to said hydraulic motor in response to pilot pressure signals; means for sensing the velocity of the movable element and producing an actual velocity signal indicative of said sensed position; means for sensing the velocity of the movable element and producing an actual velocity signal indicative of said sensed velocity; means for receiving said position request signal and said actual position signal and responsively producing a desired velocity signal; means for receiving said actual velocity signal and said desired velocity signals and responsively producing a velocity error signal; means for receiving said desired velocity signal and said velocity error signal, and responsively producing a flow command signal as a function of said desired velocity signal and said velocity error signal; and, means for receiving said flow command signal and responsively producing a pilot pressure signal and delivering said pilot pressure signal to said hydraulic fluid delivering means.
Claim 10
Dependent Claim
23 words
An apparatus, as set forth in claim 7, wherein said hydraulic motor is a hydraulic cylinder and said movable element is a piston.
Claim 11
Dependent Claim
15 words
An apparatus, as set forth in claim 7, including means for providing feed forward compensation.
Claim 12
Dependent Claim
34 words
An apparatus, as set forth in claim 7, wherein said velocity sensing means includes means for receiving said position signal and for determining said actual velocity signal by filtering and differentiating said position signal.
Claim 13
Dependent Claim
20 words
An apparatus, as set forth in claim 7, wherein said pilot pressure signal is proportional to said flow command signal.
Claim 14
Dependent Claim
18 words
An apparatus, as set forth in claim 7, wherein said hydraulic fluid delivering means includes a directional valve.
Claim 15
Dependent Claim
16 words
An apparatus, as set forth in claim 12, wherein said directional valve has an overlapped spool.
Claim 16
Dependent Claim
16 words
An apparatus, as set forth in claim 12, wherein said directional valve has a critically-lapped spool.
Claim 17
Dependent Claim
16 words
An apparatus, as set forth in claim 12, wherein said directional valve has an underlapped spool.
Claim 18
Dependent Claim
22 words
An apparatus, as set forth in claim 12, wherein said directional valve has an extend, a neutral and a retract flow position.
Claim 19
Independent Claim
127 words
A method for controllably moving a movable element within a hydraulic motor in response to a flow request signal, comprising the steps of: sensing the actual velocity of said movable element and responsively producing an actual velocity signal; receiving said flow request signal command and said actual velocity signal and responsively producing a desired velocity signal; receiving said desired velocity signal and said actual velocity signal and responsively producing a velocity error signal; receiving said velocity error signal and said desired velocity signal and responsively producing a flow command signal as a function of said desired velocity signal and said velocity error signal; and receiving said flow command signal and producing a flow of hydraulic fluid to said hydraulic motor in response to said flow command signal.
Claim 20
Independent Claim
127 words
A method for controllably moving a movable element within a hydraulic motor in response to a flow request signal, comprising the steps of: sensing the actual velocity of said movable element and responsively producing an actual velocity signal; receiving said flow request signal command and said actual velocity signal and responsively producing a desired velocity signal; receiving said desired velocity signal and said actual velocity signal and responsively producing a velocity error signal; receiving said velocity error signal and said desired velocity signal and responsively producing a flow command signal as a function of said desired velocity signal and said velocity error signal; and receiving said flow command signal and producing a flow of hydraulic fluid to said hydraulic motor in response to said flow command signal.
Claim 21
Dependent Claim
32 words
A method, as set forth in claim 17, wherein said velocity error signal producing step includes the step of determining the difference between said actual velocity signal and said desired velocity signal.
Claim 22
Independent Claim
141 words
A method for controllably positioning a movable element in a hydraulic motor in response to an position request signal, comprising the steps of: sensing the actual position of said movable element and responsively producing an actual position signal; sensing the actual velocity of said movable element and responsively producing an actual velocity signal; receiving said position request signal and said actual position signal and responsively producing a desired velocity signal; receiving said desired velocity signal and said actual velocity signal and responsively producing a velocity error signal; receiving said velocity error signal and said desired velocity signal and responsively producing a flow command signal as a function of said desired velocity signal and said velocity error signal; and receiving said flow command signal and producing a flow of hydraulic fluid to said hydraulic motor in response to said flow command signal.
Claim 23
Independent Claim
141 words
A method for controllably positioning a movable element in a hydraulic motor in response to an position request signal, comprising the steps of: sensing the actual position of said movable element and responsively producing an actual position signal; sensing the actual velocity of said movable element and responsively producing an actual velocity signal; receiving said position request signal and said actual position signal and responsively producing a desired velocity signal; receiving said desired velocity signal and said actual velocity signal and responsively producing a velocity error signal; receiving said velocity error signal and said desired velocity signal and responsively producing a flow command signal as a function of said desired velocity signal and said velocity error signal; and receiving said flow command signal and producing a flow of hydraulic fluid to said hydraulic motor in response to said flow command signal.
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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) | 1996-06-14 | 1996-12-14 | 1997-06-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-06-14 | 2000-12-14 | 2001-06-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-06-14 | 2004-12-14 | 2005-06-15 | $7700.00 | Window Closed / Lapsed |