Bellows-type pump and metering system

Claim 1

A system for the metered pumping and dispensing of fluid comprising a filter means for filtering pumped fluid, a pump connected to said filter means to pump fluid thereinto, said pump comprising a positive displacement pump of the type which includes a tubular, longitudinally-contractable bellows to receive fluid for pumping; fluid-activated reciprocating means to expand and contract the bellows; means to selectively introduce working fluid to the reciprocating means to actuate the same; a rigid fluid-tight chamber formed to surround the bellows; and means to selectively introduce working fluid into said chamber and to exhaust working fluid therefrom; a discharge means connected to receive filtered fluid from said filter means; and a drawback mechanism mounted in communication with said discharge means to prevent dripping of pumped fluid from the outlet of said discharge means, the drawback mechanism comprising a mechanism housing with an aperture leading to an internal cavity within the housing, a first and second chamber formed within said cavity, a first flexible diaphragm sealingly affixed within the housing so as to create a fluid tight boundary between the first and second chamber, a reciprocable member slidingly mounted within the first chamber and in abutment with the first diaphragm, biasing means for holding the reciprocable member in abutment with the first diaphragm, a passage in the housing connecting the second chamber with a source of pressurized working fluid, and a second flexible diaphragm sealingly affixed over said aperture which opens into the first chamber and connected to a distal end of the reciprocable member.

Claim 2

A system for the metered pumping and dispensing of fluid comprising a filter means for filtering pumped fluid, a pump connected to said filter means to pump fluid thereinto, said pump comprising a positive displacement pump of the type which includes a tubular, longitudinally-contractable bellows to receive fluid for pumping; fluid-activated reciprocating means to expand and contract the bellows; means to selectively introduce working fluid to the reciprocating means to actuate the same; a rigid fluid-tight chamber formed to surround the bellows; and means to selectively introduce working fluid into said chamber and to exhaust working fluid therefrom; a discharge means connected to receive filtered fluid from said filter means; and a drawback mechanism mounted in communication with said discharge means to prevent dripping of pumped fluid from the outlet of said discharge means, the drawback mechanism comprising a mechanism housing with an aperture leading to an internal cavity within the housing, a first and second chamber formed within said cavity, a first flexible diaphragm sealingly affixed within the housing so as to create a fluid tight boundary between the first and second chamber, a reciprocable member slidingly mounted within the first chamber and in abutment with the first diaphragm, biasing means for holding the reciprocable member in abutment with the first diaphragm, a passage in the housing connecting the second chamber with a source of pressurized working fluid, and a second flexible diaphragm sealingly affixed over said aperture which opens into the first chamber and connected to a distal end of the reciprocable member.