Patent ID: 6299419
Filing Date: 2001-10-09
Classification: F04B,F05C

Abstract:
A pump for dispensing an accurate dose of a liquid product, said pump comprising:a pump housing;an inner pump chamber for receiving and containing a liquid product to be dosed;a cylinder contained within the housing;a dosing piston configured for sliding within said cylinder, said piston forming, in combination with said cylinder, a compression chamber during a stroke cycle of the dosing piston;a gap formed between the dosing piston and cylinder, said gap being hydrodynamically sealed by the liquid product occupying the inner pump chamber and the compression chamber;a diaphragm connected to said dosing piston, said diaphragm being in contact with the liquid product in said inner pump chamber; anda control bore formed in the cylinder for providing a fluid connection between the compression chamber and the inner chamber during a stroke cycle of the dosing piston, for permitting the liquid product to flow from the inner chamber into the compression chamber prior to dispensing.