US3912913A
Expired / Lapsed
US
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Process control method and apparatus
Assignee: Courtaulds Engineering Ltd
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Filing: 1974-04-08
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Granted: 1975-10-14
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Expires: 1994-04-08
Abstract
Abstract A method for controlling changes in the value of a process variable includes the steps of producing electrically a digital number signal representing the desired value of the variable, periodically adding to or subtracting from that number a digital number representing a required change in the variable, to produce an updated desired value signal, and comparing the latter signal or an analogue of it electrically with a signal representing the measured value of the variable to obtain a control signal for regulating the value of the variable. The method is applicable to the control of many industrial processes, for example the control of temperature in a dyebath, temperature cycles in baking ovens, pottery firing ovens and metal treatment furnaces, rates of flow of gases and liquids, tool movements in contour machine tools, and ''''loss of weight'''' feeding systems. Apparatus for carrying out the process is also described, comprising a first shift register for storing a binary number representing a desired value of the variable, a second shift register for storing a binary number representing a change to be made to the desired value in a predetermined time, programme means for receiving programme instructions and periodically transferring numbers to the second shift register, means for periodically combining the numbers in the two registers to produce an updated number and means for transferring periodically updated number signals to a comparator stage for comparison with electric signals representing the measured value of the variable to produce control signals for influencing the variable.
Inventors
- 👤 James William Bunting
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 19:37
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/1917; G05B; G05B15/00; G05B15/02; G05B19/00; G05B19/02; G05B19/04; G05B19/07; G05B19/075
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
95 words
A method for controlling changes in the value of a process variable including the steps of producing electrically a digital number signal representing the desired value of the variable, adding to that number at successive equal intervals of time the positive or negative digital number representing the magnitude of a required change in the variable, to produce an updated desired value signal, and comparing the latter signal or an analogue of it electrically with a signal representing the measured value of the variable to obtain a control signal for regulating the value of the variable.
Claim 2
Independent Claim
95 words
A method for controlling changes in the value of a process variable including the steps of producing electrically a digital number signal representing the desired value of the variable, adding to that number at successive equal intervals of time the positive or negative digital number representing the magnitude of a required change in the variable, to produce an updated desired value signal, and comparing the latter signal or an analogue of it electrically with a signal representing the measured value of the variable to obtain a control signal for regulating the value of the variable.
Claim 3
Dependent Claim
14 words
A method according to claim 1 wherein the digital number signals are binary numbers.
Claim 4
Dependent Claim
16 words
A method according to claim 1 wherein the digital number signals are binary coded decimal numbers.
Claim 5
Dependent Claim
60 words
A method according to claim 1 including the step of periodically comparing the signal representing the desired value of the variable with a signal representing the final value it is to achieve and thereby producing a further signal determining automatically whether the said number representing the required change is to be added to or subtracted from the desired signal value.
Claim 6
Dependent Claim
111 words
Apparatus for controlling a process variable comprising a first shift register for transient storage of a binary number representing a desired value of the variable, a second shift register for momentarily storing a binary number representing a chaNge to be made to the desired value in a predetermined time, programme means for receiving programme instructions and periodically transferring numbers to the second shift register, means for periodically combining the numbers in the two registers to produce an updated number and means for transferring periodically updated number signals to a comparator stage for comparison with electric signals representing the measured value of the variable to produce control signals for influencing the variable.
Claim 7
Dependent Claim
111 words
Apparatus for controlling a process variable comprising a first shift register for transient storage of a binary number representing a desired value of the variable, a second shift register for momentarily storing a binary number representing a chaNge to be made to the desired value in a predetermined time, programme means for receiving programme instructions and periodically transferring numbers to the second shift register, means for periodically combining the numbers in the two registers to produce an updated number and means for transferring periodically updated number signals to a comparator stage for comparison with electric signals representing the measured value of the variable to produce control signals for influencing the variable.
Claim 8
Dependent Claim
38 words
Apparatus according to claim 5 wherein the means for combining the numbers in the two registers comprises a serial adder for adding the number stored in the second shift register to that stored in the first shift register.
Claim 9
Dependent Claim
95 words
Apparatus according to claim 6 wherein the programme means includes means responsive to a programme instruction indicating the final value to be achieved by the variable to produce an electric signal representing the final value and the comparator stage includes means for comparing periodically the desired value with the final value for producing a ''subtract'' signal when the desired value exceeds the final value, including inversion means responsive to the said ''subtract'' signal for feeding the complement of the number stored in the second shift register to the serial adder instead of that number itself.
Claim 10
Dependent Claim
32 words
Apparatus according to claim 7 wherein the electric signal representing the final value is a digital signal and the means for comparing it with the desired value signal is a digital device.
Claim 11
Dependent Claim
50 words
Apparatus according to claim 7 wherein the electric signal representing the final value is an analogue signal, including a digital-to-analogue converter for receiving the said updated numbers and producing analogue signals representing the said numbers, the means for comparing the desired value with the final value being an analogue device.
Claim 12
Dependent Claim
46 words
Apparatus according to claim 5 including an analogue sensor for measuring the actual value of the variable and producing a voltage signal representing this measured value, and an analogue-to-digital converter for producing a digital signal representing the measured value, the comparator stage including a digital device.
Claim 13
Dependent Claim
50 words
Apparatus according to claim 5 including an analogue sensor for measuring the actual value of the variable and producing a voltage signal representing this measured value, a digital-to-analogue converter for receiving the said updated numbers and producing analogue signals representing the said numbers, the comparator stage including an analogue device.
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) | 1978-10-13 | 1979-04-14 | 1979-10-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-13 | 1983-04-14 | 1983-10-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-13 | 1987-04-14 | 1987-10-14 | $7700.00 | Window Closed / Lapsed |