Diaphragm pump

Claim 1

A diaphragm pump comprising: a hydraulic cylinder having opposite ends; a piston within said cylinder and generally dividing said cylinder into opposite, first and second, cavities and enclosed by said first and second ends; first and second piston rods connected to said piston and extending oppositely through said cavities and extending through said first and second ends from said cylinder; first and second pump enclosures; a first diaphragm being positioned in said first enclosure and dividing said first enclosure into first and second chambers, said first chamber being adjacent said first end of said cylinder and being connected to and driven by said first piston rod, and a second diaphragm positioned in said second enclosure and dividing said second enclosure into third and fourth chambers, said third chamber being adjacent said second end of said hydraulic cylinder and said second diaphragm being connected to and driven by said second piston rod; a first metal plate attached to said first diaphragm on the first chamber side of said first diaphragm; a second metal plate attached to said second diaphragm on the third chamber side of said second diaphragm; an electrically operated four-way valve means responsive to first and second signals for alternately applying pressurized fluid to said first and second cavities in said cylinder; first proximity switching means including a first proximity switch adjacent said first chamber of said first enclosure and being positioned to sense when said first metal plate and said first diaphragm are moved, contracting said first chamber, and enlarging said second chamber for providing said first signal to said four-way valve means; second proximity switching means including a second proxmity switch positioned adjacent said third chamber of said second enclosure and being positioned to sense when said second metal plate and said second diaphragm are moved, contracting said third chamber, and enlarging said fourth chamber for providing said second signal to said four-way valve means; valving means coupled to said second chamber of said first enclosure and said fourth chamber of said second enclosure for enabling material to be drawn in when a said diaphragm is moved in a direction toward a said proximity switch and discharged when a said diaphragm is moved away from a said proximity switch; and coupling means for interconnecting said first chambers of said enclosures, whereby pressure between said first and third chambers are equalized.