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

• Current Assignee: Thomas W. Hamilton
• Original Assignee: Thomas W. Hamilton
• Inventors: Hamilton, Thomas W.
• Primary Examiner(s): Croyle, Carlton R.
• Assistant Examiner(s): Gluck, Richard E.
• Application Number:
  US05/508,697
• Time in Patent Office: 596 Days
• Field of Search: 417/395, 417/394, 417/148, 417/149, 417/87
• US Class Current: 417/395
• CPC Class Codes: F04B 43/073 the actuating fluid being controlled by at least one valve
• CPC Class Codes: Y10T 137/7891 Flap or reed

Abstract

An air pressure-operated membrane pump for pumping a liquid comprises a housing including a chamber which is divided into liquid and air compartments by a floppy flexible membrane extending across it. The air compartment has an air inlet and outlet connected by a duct to the throat of a venturi to which an air supply under pressure is connected. The outlet from the venturi is controlled by a control valve which is itself opened and closed by the movement of the diaphragm to which a closure member of the valve is connected by a control member. When the valve is open, air flows through the venturi and causes air to be drawn from the air compartment of the pump to move the diaphragm in a direction to draw liquid into the liquid compartment in an intake stroke. At the end of this stroke, the part of the membrane to which the control member is fixed moves and closes the control valve. This causes air under pressure to flow from the throat of the venturi into the air compartment to move the diaphragm in a direction to expel liquid from the liquid compartment in a pumping stroke and again at the end of this stroke movement of the diaphragm moves the control member to shut the valve so that the cycle of operations is repeated, the control of operation of the pump thus being effected entirely by the movement of the membrane itself without any external agency.

Claims

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.

2. A gas pressure-operated membrane pump for pumping liquids, said pump comprising a housing defining a chamber, a limp flexible dished diaphragm in said chamber, a gas pressure compartment on one side of said diaphragm within said chamber, a liquid pumping compartment on the other side of said diaphragm 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 diaphragm for movement of said control member by said diaphragm 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 diaphragm is displaced within said gas pressure compartment, gas under pressure is admitted to said gas pressure compartment and parts of said diaphragm spaced from said means attaching said diaphragm to said control member are displaced to reduce the volume of said pumping compartment to discharge liquid thereform in a discharge stroke, and shortly before the end of said discharge stroke, said diaphragm 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 diaphragm spaced from said means attaching said diaphragm 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 diaphragm 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 mounting said diaphragm in a position extending across chamber with said pumping compartment on one side of said dished diaphragm and said gas pressure compartment on the other side of said diaphragm, and said means attaching said control member is fixed to said diaphragm at or near the center thereof, and said control member comprising a rod, which is fixed to the center of said diaphragm and which extends transversely to said diaphragm, and further comprising means defining an opening through said housing from said gas pressure compartment, said rod being slidably mounted in said opening, and seal means surrounding said rod, whereby the effective area of that face of said diaphragm which is directed towards said gas pressure compartment is less than the effective area of that face of said diaphragm which is directed towards said pumping compartment, so that an out-of-balance force is produced by unbalanced gas and liquid pressure on said diaphragm, said out-of-balance force acting on said rod and constituting said means for restraining said rod and said valve member in at least one of said first and second end positions.

3. A gas pressure-operated membrane pump for pumping liquids, said pump comprising a housing defining a chamber, a limp flexible dished diaphragm in said chamber, a gas pressure compartment on one side of said diaphragm within said chamber, a liquid pumping compartment on the other side of said diaphragm 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 diaphragm for movement of said control member by said diaphragm 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 diaphragm is displaced within said gas pressure compartment, gas under pressure is admitted to said gas pressure compartment and parts of said diaphragm spaced from said means attaching said diaphragm 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 diaphragm 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 diaphragm spaced from said means attaching said diaphragm 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 diaphragm 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 mounting said diaphragm in a position extending across said chamber with said pumping compartment on one side of said dished diaphragm and said gas pressure compartment on the other side of said diaphragm, and said means attaching said control member is fixed to said diaphragm at or near the center thereof, and said control member comprising a rod, which is fixed to the center of said diaphragm and which extends transversely to said diaphragm, and further comprising means defining an opening through said housing from said gas pressure compartment, said rod being slidably mounted in said opening, and seal means surrounding said rod, whereby the effective area of that face of said diaphragm which is directed towards said gas pressure compartment is less than the effective area of that face of said diaphragm which is directed towards said pumping compartment, so that an out-of-balance force is produced by unbalanced gas and liquid pressure on said diaphragm, said out-of-balance force acting on said rod and constituting said means for restraining said rod and said valve member in at least one of said first and second end positions, and said control valve means including means mounting said valve member on said rod and freely movable piston means beyond the end of said rod remote from said diaphragm and operatively mounted to actuate said rod and valve member, and said pump further comprises means defining gas passages placing said piston means in communication with said gas pressure compartment, whereby said piston means is acted upon by gas under a pressure equal to that pertaining in said gas pressure compartment, said piston means being of the same cross-sectional area as said rod whereby said piston means applies a force to said rod which is opposite in direction, but equal in magnitude, to said out-of-balance force which acts on said rod when said rod and said valve member are in said first end positions, and said control valve means further comprising seat means surrounding an area greater than said cross-sectional area of said rod and said valve member including closure means fixed to said rod and seating on said seat means when said valve member is in said first end position thereof, whereby a force produced by gas pressure acting on said closure means within said area bounded by said seat produces a force which forms said means for restraining said control member and said valve member in said first end positions thereof.

4. A pump as claimed in claim 3 in which said closure means comprises a flange of material of rubber-like resilience projecting radially from said rod.