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Bellows-type pump and metering system

  • US 4,483,665 A
  • Filed: 01/19/1982
  • Issued: 11/20/1984
  • Est. Priority Date: 01/19/1982
  • Status: Expired due to Term
First Claim
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1. A system for the metered pumping and dispensing of fluid comprisinga filter means for filtering pumped fluid,a pump connected to said filter means to pump fluid thereinto, said pump comprising a positive displacement pump of the type which includes a tubular, longitudinally-contractable bellows to receive fluid for pumping;

  • fluid-activated reciprocating means to expand and contract the bellows;

    means to selectively introduce working fluid to the reciprocating means to actuate the same;

    a rigid fluid-tight chamber formed to surround the bellows; and

    means to selectively introduce working fluid into said chamber and to exhaust working fluid therefrom;

    a discharge means connected to receive filtered fluid from said filter means; and

    a drawback mechanism mounted in communication with said discharge means to prevent dripping of pumped fluid from the outlet of said discharge means, the drawback mechanism comprising a mechanism housing with an aperture leading to an internal cavity within the housing, a first and second chamber formed within said cavity, a first flexible diaphragm sealingly affixed within the housing so as to create a fluid tight boundary between the first and second chamber, a reciprocable member slidingly mounted within the first chamber and in abutment with the first diaphragm, biasing means for holding the reciprocable member in abutment with the first diaphragm, a passage in the housing connecting the second chamber with a source of pressurized working fluid, and a second flexible diaphragm sealingly affixed over said aperture which opens into the first chamber and connected to a distal end of the reciprocable member.

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