Patent ID: 6481982
Filing Date: 2002-11-19
Classification: F04B

Abstract:
A diaphragm pump comprising a pumping chamber having a wall formed by a diaphragm reciprocatingly movable to suck and discharge a liquid to be processed into and out of said pumping chamber;a working fluid chamber separated by said diaphragm from said pumping chamber and containing a working fluid for transmitting a pressure change, said working fluid chamber having a wall disposed facing said diaphragm, said wall having a cavity with an opening formed in a surface of said wall, said cavity having a bottom face opposite said opening; a diaphragm driving mechanism operative to impart cyclic pressure fluctuation to the working fluid in said working fluid chamber to thereby reciprocate said diaphragm; a guidance member fixed onto said bottom face and projecting therefrom into said cavity; a working fluid vessel containing said working fluid; a working fluid supply passage connecting said working fluid vessel with said working fluid chamber via said cavity; and a working fluid control valve for closing and opening said working fluid supply passage, said working fluid control valve comprising: a valve member around said guide member, said valve member being reciprocatingly movable along said guide member in front of said diaphragm and operative to close the opening of said cavity; a mechanism for biasing said valve member so as to project said valve member out of the opening of said cavity; a working fluid supply passage opening/shutting device for opening said working fluid supply passage when said valve member is positioned close to the opening of said cavity and for closing said working fluid supply passage when said valve member projects from the opening of said cavity; and a mechanism for limiting the maximum distance over which a valve head of said valve member projects from the opening of said cavity.