Patent US4485729A successfully refreshed from Google Patents.
US4485729A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control of the atmosphere in an enclosure
Assignee: Australian Government
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Filing: 1984-02-02
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Granted: 1984-12-04
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Expires: 2004-02-02
Abstract
Abstract A method of controlling an atmosphere in an enclosure (12) to which gas (40) is being supplied comprises the steps of monitoring (53) atmospheric pressure within the enclosure and the rate of gas flow to (52) or from the enclosure, comparing these parameters (62) with adjustable set points to obtain error values and adjusting inflow (50) and exhaust (51) valves for the enclosure in dependence upon the error values. A preferred method includes the intermediate steps of deriving from the error values, target positions for the valves. Also disclosed is an installation incorporating a control system for carrying out the method.
Inventors
- 👤 Mark D. Crittenden
- 👤 Graeme J. Lowe
- 👤 Neil S. McLaren
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:57
CPC Classifications
G; G05; G05D; G05D16/00; G05D16/20; G05D16/2006; G05D16/2013; G05D16/2026; G05D16/2046; G05D16/2053; B; B01; B01L; B01L1/00; B01L1/04; F; F24; F24F; F24F11/00; F24F11/0001; F24F11/70; F24F11/72; F24F11/74; F24F2011/0002; F24F2011/0005; F24F2110/00; F24F2110/40; F24F2140/00; F24F2140/40
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
105 words
A method of controlling an atmosphere in an enclosure to which gas is being supplied, comprising: monitoring two parameters, being atmospheric pressure within the enclosure and the rate of gas flow to or from the enclosure and conveying monitored values obtained thereby to a control means; comparing at the control means the monitored values of these parameters with respective adjustable set points to obtain pressure and rate of flow error values; determining respective adjustments of gas inflow and exhaust valves for the enclosure, each in dependence upon both of said error values, if necessary, effecting said adjustments of the valves to said adjustable set points.
Claim 2
Independent Claim
105 words
A method of controlling an atmosphere in an enclosure to which gas is being supplied, comprising: monitoring two parameters, being atmospheric pressure within the enclosure and the rate of gas flow to or from the enclosure and conveying monitored values obtained thereby to a control means; comparing at the control means the monitored values of these parameters with respective adjustable set points to obtain pressure and rate of flow error values; determining respective adjustments of gas inflow and exhaust valves for the enclosure, each in dependence upon both of said error values, if necessary, effecting said adjustments of the valves to said adjustable set points.
Claim 3
Dependent Claim
35 words
A method according to claim 1, wherein said-determining includes: deriving, from both of said error values in accordance with pre-determined functions, target values for the positions of gas inflow and exhaust valves for the enclosure.
Claim 4
Dependent Claim
77 words
A method according to claim 2, wherein said valves are selected to exhibit substantially identical dependence of rate of flow on valve position and also to exhibit similar authority in the supply and exhaust configurations; and said functions include terms contributing to said adjustments of the gas inflow and exhaust valves in the same direction in similar proportion to the rate of flow error value, and in opposite directions in similar proportion to the pressure variation value.
Claim 5
Dependent Claim
97 words
A method according to claim 3 wherein said pre-determined functions are essentially of the form of T.sub.1 =I.sub.1 +AP.sub.E +BF.sub.E +P(P.sub.E)+D(P.sub.E) T.sub.2 =I.sub.2 -AP.sub.E +BF.sub.E -P(P.sub.E)-D(P.sub.E) where T 1 is the inflow valve target value T 2 is the exhaust valve target value I 1 and I 2 are the present integral values of the respective values P E is the pressure error F E is the rate of flow error P(P E ) is a proportional function of P E D(P E ) is a derivative function of P E , and A,B are scaling constants.
Claim 6
Dependent Claim
39 words
A method according to claim 1, wherein the two parameters monitored are pressure within the enclosure and the rate of gas flow into the enclosure, and (in that) said rate of flow error value is an inflow error value.
Claim 7
Dependent Claim
34 words
A method according to claim 1, including obtaining a modified flow error value by reducing the magnitude of said rate of flow error value in proportion to the magnitude of the pressure error value.
Claim 8
Dependent Claim
29 words
A method according to claim 1, including comparing said error values with predetermined respective limits selected to smooth fluctuations and to reduce the frequency of operation of the valves.
Claim 9
Dependent Claim
38 words
A method according to claim 2 wherein the valves are adjusted by controlling solenoids of the valves in dependence upon a comparison of the target values and fed back signals indicative of the positions of the respective valves.
Claim 10
Dependent Claim
115 words
An installation including a controlled atmosphere enclosure, gas inflow and exhaust valves for the enclosure, and a control system comprising: means to monitor two parameters, being atmospheric pressure within the enclosure and the rate of gas flow to or from the enclosure, and to output respective first signals representative of the monitored values of the parameters; means connected to receive said first signals to compare the monitored values of said parameters with respective adjustable set points to obtain pressure and rate of flow error values; means to determine respective adjustments of said gas inflow and exhaust valves, each in dependence upon both of said error values; and means to effect said adjustment of the valves.
Claim 11
Dependent Claim
115 words
An installation including a controlled atmosphere enclosure, gas inflow and exhaust valves for the enclosure, and a control system comprising: means to monitor two parameters, being atmospheric pressure within the enclosure and the rate of gas flow to or from the enclosure, and to output respective first signals representative of the monitored values of the parameters; means connected to receive said first signals to compare the monitored values of said parameters with respective adjustable set points to obtain pressure and rate of flow error values; means to determine respective adjustments of said gas inflow and exhaust valves, each in dependence upon both of said error values; and means to effect said adjustment of the valves.
Claim 12
Dependent Claim
37 words
An installation according to claim 9 wherein said determining means includes means to derive, from both of said error values in accordance with pre-determined functions, target values for the positions of said gas inflow and exhaust valves.
Claim 13
Dependent Claim
77 words
An installation according to claim 10 wherein said valves are selected to exhibit substantially identical dependence of rate of flow on valve position and also to exhibit similar authority in the supply and exhaust configurations; and said functions include terms contributing to said adjustments of the gas inflow and exhaust valves in the same direction in similar proportion to the rate of flow error value, and in opposite directions in similar proportion to the pressure variation value.
Claim 14
Dependent Claim
68 words
An installation according to claim 9 wherein said means for effecting said adjustments includes a respective pair of solenoids for opening and closing each valve, means arranged to produce a signal indicative of the position of each valve, and second comparing means for controlling the solenoids in dependence upon a comparison of the respective valve position signals and the adjustment required on the basis of said target values.
Claim 15
Dependent Claim
35 words
An installation according to claim 9 wherein said comparing, determining and deriving means comprise a suitably programmed microprocessor coupled to receive said first signals and to output command signals for said valves via suitable interfacing.
References Cited (Backward Citations)
US3078778A
Cited
US3107974A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-12-04 | 1988-06-04 | 1988-12-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-12-04 | 1992-06-04 | 1992-12-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-12-04 | 1996-06-04 | 1996-12-04 | $7700.00 | Window Closed / Lapsed |