US4366743A
Expired / Lapsed
US
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Control system for doser actuator
Assignee: Bendix Corp
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Filing: 1980-10-27
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Granted: 1983-01-04
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Expires: 2000-10-27
Abstract
Abstract A control system 54 for a doser type hydraulic actuator 56 is disclosed. The doser actuator includes a pair of unequal area pistons 18, 20 on a common shaft 16 which are moved incrementally by injecting into or removing from a control pressure chamber metered quantities or doses of fluid. The doses are metered by timed openings of solenoid valves 32, 34 connecting the control pressure chambered to a supply 44 or return 48 pressure sources. The control system includes a base pulse width signal generator 106 which pulse modulates the solenoids as a function of the error between a requested position and an actual position. The base pulse width is modified by a correction means 108, 110, 112 when the error is within a predetermined band width. The correcting means compensates for the variations of the actuator when its response is uncertain with respect to the base pulse width.
Inventors
- 👤 Michael J. Leszczewski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:31
CPC Classifications
F; F15; F15B; F15B9/00; F15B9/02; F15B9/03; G; G05; G05D; G05D3/00; G05D3/12; G05D3/14; G05D3/18
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
234 words
In a closed loop control system for an electrohydraulic actuator having means responsive to a periodic pulse width signal, for moving the actuator in one direction; means, also responsive to the pulse width signal, for moving the actuator in the other direction; means for generating the pulse width signal from a schedule with a dead band wherein the schedule is based upon an error signal representative of the difference between the actual actuator position and a desired actuator position; means for gating said pulse width signal to said moving means according to the polarity of the error signal such that the actuator moves in a direction to null said error signal; means for correcting the pulse width signal with an incrementally increasing signal, said increasing signal being incremented each time period that the scheduled pulse width is uncertain to move the actuator in a direction to null the error, said correcting means having a counter which is clocked by a timing signal for each timing period, and means receiving the output count of said counter for converting the count into said increasing signal, wherein the improvement comprises: means for selecting time periods when the counter is cleared such that the counter is cleared when the polarity of said error signal changes, said error signal is less than the dead band value, or the change in the error signal is greater than the dead band.
Claim 2
Dependent Claim
234 words
In a closed loop control system for an electrohydraulic actuator having means responsive to a periodic pulse width signal, for moving the actuator in one direction; means, also responsive to the pulse width signal, for moving the actuator in the other direction; means for generating the pulse width signal from a schedule with a dead band wherein the schedule is based upon an error signal representative of the difference between the actual actuator position and a desired actuator position; means for gating said pulse width signal to said moving means according to the polarity of the error signal such that the actuator moves in a direction to null said error signal; means for correcting the pulse width signal with an incrementally increasing signal, said increasing signal being incremented each time period that the scheduled pulse width is uncertain to move the actuator in a direction to null the error, said correcting means having a counter which is clocked by a timing signal for each timing period, and means receiving the output count of said counter for converting the count into said increasing signal, wherein the improvement comprises: means for selecting time periods when the counter is cleared such that the counter is cleared when the polarity of said error signal changes, said error signal is less than the dead band value, or the change in the error signal is greater than the dead band.
Claim 3
Dependent Claim
74 words
A closed loop control system for an electrohydraulic actuator as defined in claim 1, wherein said selecting means comprises: means for comparing the absolute value of the error signal with the dead band limits; means for comparing the change in the absolute value of the error signal with the dead band limits; and means for comparing the polarity of said error signal with the polarity of the error signal for the previous time period.
Claim 4
Dependent Claim
43 words
A closed loop control system for an electrohydraulic actuator as defined in claim 2, werein said absolute value comparing means includes: a window comparator which outputs a high level signal if the absolute value of the error signal is within the dead band.
Claim 5
Dependent Claim
76 words
A closed loop control system for an electrohydraulic actuator as defined in claim 3, wherein said change in the absolute value comparing means includes: means for storing the absolute value of the error signal for the previous period; means for differencing the present and previous absolute value error signals; and a second window comparator which outputs a high level signal if the difference between the present and previous error signals is larger than the dead band.
Claim 6
Dependent Claim
131 words
A closed loop control system for an electrohydraulic actuator as defined in claim 4, wherein the polarity comparing means includes: means for storing the absolute value of the error signal for the previous period; means for storing the value of the error signal for the previous period; means for dividing the absolute value of the error signal by the error signal and generating a first quotient; second means for dividing the absolute value of the previous error signal by the value of the previous error signal and generating a second quotient; means for differencing said first and second quotients; and third window comparator means which output a high level signal if the difference between said first and second quotients is greater than a positive one or less than a negative one.
Claim 7
Dependent Claim
56 words
A closed loop control system as defined in claim 5, wherein said selecting means includes: an OR gate, receiving the high level outputs of said window comparator, said second window comparator, and said third window comparator, for generating a high level reset signal to said counter whenever any of the comparators generate a high level output.
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) | 1986-01-03 | 1986-07-05 | 1987-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-01-03 | 1990-07-05 | 1991-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-01-03 | 1994-07-05 | 1995-01-04 | $7700.00 | Window Closed / Lapsed |