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Apparatus for controlling a valve

  • US 5,704,586 A
  • Filed: 06/21/1996
  • Issued: 01/06/1998
  • Est. Priority Date: 12/21/1993
  • Status: Expired due to Term
First Claim
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1. Apparatus for controlling movement of a valve between a number of fixed positions, comprisinga pressure cylinder for activating the valve;

  • magnetic valve means for controlling a supply of fluid from a source of pressurized fluid to said pressure cylinder;

    a valve having a valve stem;

    a linear position indicator which is connected to said valve and provides position indications relating to fixed positions of the valve occurring during movement of the valve stem;

    means for storing desired ones of said fixed position indications in a data store; and

    control means for comparing current position indications of said linear position indicator with fixed position indications stored in said data store;

    wherein said control means has program means for determining, during repeated operation of the valve, the occurrence of changes in the position indications for the fixed positions of the valve and for compensating for such changes which are within a tolerance range around a stored position indication representative of correct operation of the valve.

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