US3777122A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process and apparatus for the automatic control of a variable
Assignee: Shell USA Inc
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Filing: 1971-07-30
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Granted: 1973-12-04
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Expires: 1991-07-30
Abstract
Abstract A control system for a variable wherein the maximum rate of change of the variable is controlled by limiting the error signal. The error signal is controlled so that the control system operates linearly with time when the error signal exceeds the limit and proportionally and integrally when the error signal is less than the limit.
Inventors
- 👤 A Borsboom
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:12
CPC Classifications
G; G05; G05B; G05B11/00; G05B11/01; G05B11/36; G05B11/42; G05B5/00; G05B5/01; H; H02; H02P; H02P23/00; H02P23/16
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
201 words
A process for the automatic control of a variable, particularly of the rate of change of the variable, comprising the steps of: a. measuring the actual value of the variable and producing a corresponding signal (na), b. setting the desired value of the variable and producing a signal (nb) corresponding to the desired value, c. determining the difference between the signals na and nb which results in a signal Epsilon nb - na, d. amplifying the signal Epsilon from which a signal X is subtracted in an amplifier with a high gain A, which results in an output signal z -A( Epsilon - X). e. limiting the signal z so as not to exceed an upper-positivevalue +l and a lower-negative-value - l, which results in a signal z'', f. integrating the signal z'' which results in a signal I integral z''dt, g. differentiating the signal I which results in a signal X that is determined by the equation N(dX/dt) + X N(dI/dt), where N is a network constant, h. subtracting the signal X as already indicated under (d), at the input of said high gain amplifier from the signal Epsilon and i. adjusting the variable in response to the signal I.
Claim 2
Dependent Claim
201 words
A process for the automatic control of a variable, particularly of the rate of change of the variable, comprising the steps of: a. measuring the actual value of the variable and producing a corresponding signal (na), b. setting the desired value of the variable and producing a signal (nb) corresponding to the desired value, c. determining the difference between the signals na and nb which results in a signal Epsilon nb - na, d. amplifying the signal Epsilon from which a signal X is subtracted in an amplifier with a high gain A, which results in an output signal z -A( Epsilon - X). e. limiting the signal z so as not to exceed an upper-positivevalue +l and a lower-negative-value - l, which results in a signal z'', f. integrating the signal z'' which results in a signal I integral z''dt, g. differentiating the signal I which results in a signal X that is determined by the equation N(dX/dt) + X N(dI/dt), where N is a network constant, h. subtracting the signal X as already indicated under (d), at the input of said high gain amplifier from the signal Epsilon and i. adjusting the variable in response to the signal I.
Claim 3
Dependent Claim
60 words
A process according to claim 1, which process is applied to a steam turbine installation on board a ship for driving the ship''s propeller, the signal na representing the actual number of revolutions of the ship''s propeller, the signal nb representing the desired number of revolutions and the signal I being used for adjusting the steam supply to the turbine.
Claim 4
Dependent Claim
20 words
A process according to claim 1 in which the upper-positive-value and the lower-negative-value have the same absolute value, namely l.
Claim 5
Dependent Claim
38 words
A process according to claim 3 in which the upper-positive-and the lower-negative-value are derived from the signal I in such a way that if the absolute value of I is small the absolute value of l is large.
Claim 6
Dependent Claim
60 words
A process according to claim 2 in which the upper-positive-value and the lower-negative-value are obtained by measuring the mass flow rate of the steam supplied to the turbine, by differentiating the measured value and by comparing the absolute value of that differential with a set value to obtain an output signal used for setting the values + l and -l.
Claim 7
Independent Claim
166 words
An apparatus for the automatic control of a variable, which apparatus comprises: aa. a meter measuring the actual value of that variable, bb. a component for setting the desired value of that variable, cc. a subtracting element, of which one input is connected to the meter and the other input to the component, dd. an amplifier with a high gain, whose input is connected to the output of the subtracting element, ee. a first selector for the largest incoming signal, of which one input is connected to the output of the amplifier, ff. a second selector for the smallest incoming signal, of which one input is connected to the output of the first selector, gg. an integrator, of which the input is connected to the output of the second selector, hh. a correcting unit for the said variable, said correcting unit being connected to the output of the integrator, ii. a network, connected to the output of the integrator and to the input of the amplifier.
Claim 8
Independent Claim
166 words
An apparatus for the automatic control of a variable, which apparatus comprises: aa. a meter measuring the actual value of that variable, bb. a component for setting the desired value of that variable, cc. a subtracting element, of which one input is connected to the meter and the other input to the component, dd. an amplifier with a high gain, whose input is connected to the output of the subtracting element, ee. a first selector for the largest incoming signal, of which one input is connected to the output of the amplifier, ff. a second selector for the smallest incoming signal, of which one input is connected to the output of the first selector, gg. an integrator, of which the input is connected to the output of the second selector, hh. a correcting unit for the said variable, said correcting unit being connected to the output of the integrator, ii. a network, connected to the output of the integrator and to the input of the amplifier.
Claim 9
Dependent Claim
20 words
An apparatus according to claim 6, in which apparatus the network consists of an inverting amplifier and a differentiating circuit.
Claim 10
Dependent Claim
98 words
An apparatus according to claim 6, which apparatus, in addition includes a function generator whose input is connected to the output of the integrator, which function generator has an output for positive signalS that is connected to the other input of the first selector as well as an output for negative signals that is connected to the other input of the second selector, which function generator is capable of generating an upper positive value signal +l and a lower positive value signal -l, of which the absolute value is large when the absolute value of I is small.
Claim 11
Dependent Claim
134 words
An apparatus according to claim 6, suitable for application to a steam turbine installation on board a ship for driving the ship''s propeller, in which the number of revolutions of the ship''s propeller is the variable referred to, which apparatus in addition includes a meter measuring the mass flow rate of the steam supplied to the turbine, which meter is connected to an element that is capable of providing the absolute value of the differential of the incoming signal, of which element the output is connected to the input for the measured value of a controller having proportional action, of which the ouput is connected to the other input of the first selector, and of which controller the output is also connected, via an inverting amplifier, to the other input of the second selector.
References Cited (Backward Citations)
US3201675A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-03 | 1977-06-04 | 1977-12-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-03 | 1981-06-04 | 1981-12-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-03 | 1985-06-04 | 1985-12-04 | $7700.00 | Window Closed / Lapsed |