Fluid flow control system
First Claim
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1. A fluid flow control system, comprising:
- (A) a fluid control valve, the flow of fluid through said valve varying as a function of the position of said valve;
(B) valve adjust means for adjusting the position of said control valve as a function of a valve position signal; and
(C) control means for generating a new said valve position signal during each of a plurality of sampling intervals N, said control means generating said valve position signal by;
(1) computing, during each successive sampling interval N, the rate of flow of fluid through said valve as a function of the position of said valve and in accordance with the static flow equation for said valve; and
(2) generating said new valve position signal as a function of the difference between a desired flow and said computed flow and in accordance with a non-linear control transfer function which limits said valve position signal, and therefore limits the change in position of said valve between the present sampling interval N and the following sampling interval N+1, to a value which ensures that the actual flow of fluid through said valve during said following sampling interval N+1 is substantially equal to the flow predicted by said static flow equation.
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Abstract
A fluid flow control system for controlling the flow of fluid through a valve is disclosed. The control system controls the flow of fluid through the valve by varying the position of the valve. The control system performs this function in such a manner that the change in position of the valve at all times remains sufficiently bounded so as to ensure that the actual flow of fluid through the valve is substantially equal to the flow predicted by the static flow equation for the valve.
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Citations
21 Claims
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1. A fluid flow control system, comprising:
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(A) a fluid control valve, the flow of fluid through said valve varying as a function of the position of said valve; (B) valve adjust means for adjusting the position of said control valve as a function of a valve position signal; and (C) control means for generating a new said valve position signal during each of a plurality of sampling intervals N, said control means generating said valve position signal by; (1) computing, during each successive sampling interval N, the rate of flow of fluid through said valve as a function of the position of said valve and in accordance with the static flow equation for said valve; and (2) generating said new valve position signal as a function of the difference between a desired flow and said computed flow and in accordance with a non-linear control transfer function which limits said valve position signal, and therefore limits the change in position of said valve between the present sampling interval N and the following sampling interval N+1, to a value which ensures that the actual flow of fluid through said valve during said following sampling interval N+1 is substantially equal to the flow predicted by said static flow equation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 13)
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11. A fluid flow control system, comprising:
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(A) a fluid control valve, the flow of fluid through said valve varying as a function of the position x of said valve; (B) valve adjust means for adjusting the position of said control valve as a function of a valve position signal, and C. control means for generating a new said valve position signal during each of a plurality of sampling intervals N, said control means generating said valve position signal by; (1) computing the desired change Δ
x in the position of said valve between the present time sampling interval N and the following sampling interval N+1 as a function of the difference between said desired flow and said computed flow and in accordance with a non-linear transfer function, said non-linear transfer function limiting the size of said desired change Δ
x to a value which ensures that the actual rate of flow through said valve during the said following sampling interval N+1 is substantially equal to the flow predicted by said static equation;(2) determining the desired position of said valve during said following sampling interval N+1 by computing the sum of said desired change Δ
x and the actual position of said valve; and(3) generating said valve position signal as a function of said desired position of said valve indicated by said computed sum. - View Dependent Claims (12)
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14. A fluid flow control system, comprising:
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(A) M fluid control valves, M being a positive integer, the flow of fluid through each respective said valve varying as a function of its position; (B) M valve adjust means, each of said valve adjust means being associated with a respective said valve and adjusting the position of its associated valve as a function of P valve position signals associated with its associated valve, P being a positive integer; (C) P control means, each of said control means for generating M said valve position signals during each of a plurality of sampling intervals N, each of said valve position signals being associated with and representative of the desired position of a respective one of said valves during the next sampling interval N+1, each of said control means generating each of said M valve position signals by; (1) computing, during each successive sampling interval N, the flow of fluid through said valve with which said position signal is associated as a function of the position of said valve with which said position signal is associated and in accordance with the static flow equation for said valve with which said position signal is associated; and (2) generating said valve position signal as a function of the difference between a desired flow of fluid through said valve with which said position signal is associated and said computed flow of fluid through said valve with which said position signal is associated and in accordance with a non-linear control transfer function which limits each of said valve position signals, and therefore limits the change of position of said valve with which said position signal is associated between the present sampling interval N and the following sampling interval N+1 to values which ensure that the actual flow of fluid through said valve with which said position signal is associated during said following sampling interval N+1 is substantially equal to the flow predicted by said static flow equation for said valve with which said position signal is associated. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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Specification