Patent ID: 6152705
Filing Date: 2000-11-28
Classification: F04B,Y10T

Abstract:
A double diaphragm pump comprising two opposed pumping cavities;two diaphragms, each diaphragm extending across a pumping cavity, respectively, to define an air chamber cavity;a shaft extending between each of the diaphragms and being slidably mounted relative to the opposed pumping cavities;a housing between the pumping cavities including two valve cavities, two first ports, two second ports and two third ports through the housing to each of the valve cavities, respectively, the second ports being in communication with the air chamber cavities, respectively, the third ports extending to atmosphere;two shuttle valve elements each including a sidewall sealably and slidably positioned in the valve cavities, respectively, and a passageway therethrough with a first end, a second end and a valve seat between the first end and the second end, the first port being in communication with the first end and the second port being in communication with the second end, the shuttle valve elements each having two extreme positions, the first with the sidewall covering the third port and the second with the third port uncovered and in communication with the second port;two one-way valves in the passageways, respectively, biased against the valve seats and permitting flow from the first end to the second end of each passageway, respectively, under preselected pressure;a source of pressurized air in selective communication with the first ports;a control valve assembly, the housing further including two relief valve cavities, the control valve assembly including a control valve, control passages from the control valve to the two relief valve cavities, respectively, two pressure relief valves in the relief valve cavities, each with an actuator pin extending to be alternately depressed at preselected limits of the shaft stroke, a relief valve body having a guideway, a relief valve seat and an exhaust, a flow path from the respective control passage through the respective relief valve cavity and across the relief valve seat to the exhaust, an actuator slidably positioned in the guideway with the actuator pin, a relief valve element slidably positioned in the cavity to face the guideway and the relief valve seat and biased toward seating engagement with the valve seat, and a compression spring between the actuator and the valve element.