US4790233A
Expired / Lapsed
US
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Method and apparatus for controlling hydraulic systems
Assignee: TURNMASTER CORP
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Filing: 1987-07-08
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Granted: 1988-12-13
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Expires: 2007-07-08
Abstract
Abstract A control system is provided for a hydraulic actuating system having a multi-phase stepping motor with a driver therefor which supplies and controls DC current through each of the motor windings such that no current is induced into the control winding from adjacent windings. The stepping motor precisely controls the rotation of an eccentric cam engaging an actuating plunger which actuates a control valve of the hydraulic actuating system. The driver receives control signals from a computer programmed to calculate, from user input command signals indicative of the desired system condition, and generate those control signals which most quickly achieve a rough approximation of the desired system condition. After this rough approximation is attained, the computer generates new control signals for the driver as a function of feedback signals and/or system component characteristics so as to precisely achieve the desired system condition.
Inventors
- 👤 Bengt S. Backe
- 👤 La Moyne W. Durham
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 23:38
CPC Classifications
G; G05; G05B; G05B19/00; G05B19/02; G05B19/18; G05B19/19; G05B19/21; G05B19/23; G05B19/231; H; H02; H02P; H02P8/00; H02P8/14; G05B2219/00; G05B2219/30; G05B2219/41; G05B2219/41133; G05B2219/41309; G05B2219/41326; Y; Y10; Y10T; Y10T137/00; Y10T137/8593; Y10T137/86493; Y10T137/86574; Y10T137/86582; Y10T137/86614; Y10T137/86622
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
179 words
A method of controlling a system for generating hydraulic power, including a variable displacement pump, means for driving said variable displacement pump, means for adjusting the swash plate of said variable displacement pump in response to command signals, a fluid motor means for receiving the fluid output of said variable displacement pump and providing mechanical output power, comprising: applying an initial control signal, representative of a desired mechanical output power, to said means for adjusting said swash plate; calculating the difference between said desired mechanical output power and the actual mechanical output power to obtain an error signal; continuing to apply said initial control signal to said means for adjusting said swash plate until said error signal reaches a predetermined level; calculating the revised control signal necessary to produce zero error signal as a function of at least one of a plurality of known system component characteristics, when said error signal reaches said predetermined level; and applying said revised control signal to said means for adjusting said swash plate so as to attain precisely said desired mechanical output power.
Claim 2
Independent Claim
179 words
A method of controlling a system for generating hydraulic power, including a variable displacement pump, means for driving said variable displacement pump, means for adjusting the swash plate of said variable displacement pump in response to command signals, a fluid motor means for receiving the fluid output of said variable displacement pump and providing mechanical output power, comprising: applying an initial control signal, representative of a desired mechanical output power, to said means for adjusting said swash plate; calculating the difference between said desired mechanical output power and the actual mechanical output power to obtain an error signal; continuing to apply said initial control signal to said means for adjusting said swash plate until said error signal reaches a predetermined level; calculating the revised control signal necessary to produce zero error signal as a function of at least one of a plurality of known system component characteristics, when said error signal reaches said predetermined level; and applying said revised control signal to said means for adjusting said swash plate so as to attain precisely said desired mechanical output power.
Claim 3
Dependent Claim
36 words
The method according to claim 1, wherein said fluid motor includes a rotating output shaft to provide mechanical output power and said actual mechanical output power is calculated by monitoring the rotational speed of said shaft.
Claim 4
Dependent Claim
30 words
The method according to claim 1, wherein said revised control signals are also calculated as a function of operating conditions obtained by monitoring the fluid pressure within said fluid motor.
Claim 5
Dependent Claim
37 words
The method according to claim 1, characterized in that the functional relationship between said control signals and said error signals is such that said control signals. decrease when said error signals become less than a predetermined level.
Claim 6
Dependent Claim
281 words
A control system for hydraulic actuating systems having hydraulic pressure supply and pressure return, at least one control line for applying actuating hydraulic pressure to at least one movable element, and valve means connected between said pressure supply and said control line, for controlling pressure flow therebetween, comprising: means for precisely actuating said valve means including stepping motor means, actuating linkage means connected between said valve means and said stepping motor means, and driver means for controlling the operation of said stepping motor means by supplying DC current through each of the windings of said stepping motor means and controlling said DC current in each of said windings; wherein a fluid motor and variable displacement pump whose fluid output drives said fluid motor are provided, said movable element forming the swash plate of said variable displacement pump; and wherein said fluid motor includes a rotatable output shaft, means are provided to monitor the rotational speed of said output shaft and provide feedback signals representative thereof, digital computer means are provided to receive said feedback signals and provide control signals to said driver means for adjustment of the displacement of said swash plate according to a two part computer program algorithm which initially drives said stepping motor means, through said driver means, to quickly achieve a rough approximation of the desired swash plate position and then provides revised control signals, representative of at least one of a plurality of said feedback signals and representative of at least one of a plurality of known characteristics of the control system and the hydraulic actuating system, which cause said swash plate to precisely achieve said desired swash plate position by limited modulation about said position.
Claim 7
Dependent Claim
281 words
A control system for hydraulic actuating systems having hydraulic pressure supply and pressure return, at least one control line for applying actuating hydraulic pressure to at least one movable element, and valve means connected between said pressure supply and said control line, for controlling pressure flow therebetween, comprising: means for precisely actuating said valve means including stepping motor means, actuating linkage means connected between said valve means and said stepping motor means, and driver means for controlling the operation of said stepping motor means by supplying DC current through each of the windings of said stepping motor means and controlling said DC current in each of said windings; wherein a fluid motor and variable displacement pump whose fluid output drives said fluid motor are provided, said movable element forming the swash plate of said variable displacement pump; and wherein said fluid motor includes a rotatable output shaft, means are provided to monitor the rotational speed of said output shaft and provide feedback signals representative thereof, digital computer means are provided to receive said feedback signals and provide control signals to said driver means for adjustment of the displacement of said swash plate according to a two part computer program algorithm which initially drives said stepping motor means, through said driver means, to quickly achieve a rough approximation of the desired swash plate position and then provides revised control signals, representative of at least one of a plurality of said feedback signals and representative of at least one of a plurality of known characteristics of the control system and the hydraulic actuating system, which cause said swash plate to precisely achieve said desired swash plate position by limited modulation about said position.
Claim 8
Independent Claim
159 words
A method of controlling a hydraulic system for providing motive force, including a hydraulic fluid supply, at least one control line for applying hydraulic pressure to move at least one movable element, and valve means for controlling the flow of hydraulic fluid connected between said fluid supply and said control actuating means for said valve means line, comprising: applying an initial control signal representative of a desired position of said movable element to said actuating means; calculating the difference between said desired position and the actual position of said movable element to obtain an error signal; continuing to apply said initial control signal to said actuating means until said error signal reaches a predetermined level; calculating a revised control signal necessary to produce zero error signal as a function of at least one of a plurality of known hydraulic system characteristics, when said error signal reaches said predetermined level; and applying said revised control signal to said actuating means.
Claim 9
Independent Claim
159 words
A method of controlling a hydraulic system for providing motive force, including a hydraulic fluid supply, at least one control line for applying hydraulic pressure to move at least one movable element, and valve means for controlling the flow of hydraulic fluid connected between said fluid supply and said control actuating means for said valve means line, comprising: applying an initial control signal representative of a desired position of said movable element to said actuating means; calculating the difference between said desired position and the actual position of said movable element to obtain an error signal; continuing to apply said initial control signal to said actuating means until said error signal reaches a predetermined level; calculating a revised control signal necessary to produce zero error signal as a function of at least one of a plurality of known hydraulic system characteristics, when said error signal reaches said predetermined level; and applying said revised control signal to said actuating means.
Claim 10
Dependent Claim
39 words
The method according to claim 6, wherein said error signal is recalculated after applying said revised control signal and further revised control signals are calculated as a function of said hydraulic system characteristics and applied to said actuating means.
Claim 11
Independent Claim
148 words
A method for controlling a hydraulic system, which includes means for adjusting a condition of the system, comprising: applying an initial control signal, representative of a desired system condition, to said means for adjusting the condition of the system; generating a control signal representative of an actual system condition; calculating an error signal from said initial control signal and said actual system condition control signal; continuing to apply said initial control signal to said means for adjusting the condition of the system until said error signal reaches a predetermined level; calculating a revised control signal as a function of at least one feedback signal and as a function of at least one known characteristic of the system after said error signal reaches said predetermined level; and applying said revised control signal to said means for adjusting the condition of the system to precisely attain said desired system condition.
Claim 12
Independent Claim
148 words
A method for controlling a hydraulic system, which includes means for adjusting a condition of the system, comprising: applying an initial control signal, representative of a desired system condition, to said means for adjusting the condition of the system; generating a control signal representative of an actual system condition; calculating an error signal from said initial control signal and said actual system condition control signal; continuing to apply said initial control signal to said means for adjusting the condition of the system until said error signal reaches a predetermined level; calculating a revised control signal as a function of at least one feedback signal and as a function of at least one known characteristic of the system after said error signal reaches said predetermined level; and applying said revised control signal to said means for adjusting the condition of the system to precisely attain said desired system condition.
Claim 13
Dependent Claim
29 words
A method according to claim 8, wherein said at least one feedback signal is representative of one of a position and a velocity of an element of the system.
Claim 14
Dependent Claim
47 words
A method according to claim 8, wherein said known characteristic of the system comprises one of: a. a hysteresis characteristic of a system component; b. a response lag time of a system component; and c. a resolution characteristic of a system component, such as a stepping motor.
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) | 1991-12-13 | 1992-06-13 | 1992-12-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-12-13 | 1996-06-13 | 1996-12-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-12-13 | 2000-06-13 | 2000-12-13 | $7700.00 | Window Closed / Lapsed |