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Membrane pump

  • US 3,955,901 A
  • Filed: 09/23/1974
  • Issued: 05/11/1976
  • Est. Priority Date: 10/23/1973
  • Status: Expired due to Term
First Claim
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1. A gas pressure-operated membrane pump for pumping liquids, said pump comprising a housing defining a chamber, a limp flexible membrane in said chamber, a gas pressure compartment on one side of said membrane within said chamber, a liquid pumping compartment on the other side of said membrane within said chamber, means defining a gas inlet and outlet to said gas pressure compartment, means defining a liquid inlet and outlet to said pumping compartment, control valve means for controlling the gas supply and outlet from said gas pressure compartment, said control valve including a valve member and means operatively connected to said valve member for moving said valve member between first and second end positions, said means for moving said valve member including a control member and means attaching said control member to said membrane for movement of said control member by said membrane between first and second end positions corresponding to said first and second end positions of said valve member, means for restraining said control member and said valve member in both said first and second end positions, whereby, when said pump is connected to a pressurized gas supply and said valve member and said control member are in said first end positions wherein said means attaching said control member to said membrane is displaced within said gas pressure compartment, gas under pressure is admitted to said gas pressure compartment and parts of said membrane spaced from said means attaching said membrane to said control member are displaced to reduce the volume of said pumping compartment to discharge liquid therefrom in a discharge stroke, and shortly before the end of said discharge stroke, said membrane initiates movement said control member, against the action of said restraining means, from said first end position of said control member in the direction of said pumping compartment to said second end position thereof and said control member moves said valve member from said first end position to said second end position thereof wherein said valve member causes said gas to be exhausted from said gas pressure compartment, so that parts of said membrane spaced from said means attaching said membrane to said control member are displaced back to increase said volume of said pumping compartment and admit further liquid to said pumping compartment in an intake stroke, and shortly before the end of said intake stroke, said membrane initiates movement said control member against the action of said restraining means in the direction of said gas pressure compartment back into said first end position of said control member and said control member moves said valve member from said second end position back into said first end position thereof wherein said valve member allows further gas under pressure to be admitted to said gas pressure compartment, said pump further comprising means defining a gas inlet duct for connection to said source of gas under pressure, a venturi including a throat, means communicating said gas inlet duct with said venturi, means communicating said gas inlet and outlet to said throat and means defining a gas outlet from said venturi, said valve member being operatively arranged to close said outlet from said venturi when said valve member is in said first end position thereof and to open said outlet to atmosphere when said valve member is in said second end position thereof whereby when said valve member is in said first end position thereof gas supplied under pressure to said inlet duct pressurizes said gas pressure compartment and when said valve member is in said second end position thereof, gas from said inlet duct flows through said venturi and exhausts gas from said gas pressure compartment through said throat.

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