Patent ID: 8109415

Claim:
A foam pump comprising: a pump body ( 1 ) having a large air cavity ( 17 ), a small liquid cavity ( 14 ), a U-shape ring groove ( 8 ) formed on a bottom of the pump body ( 1 ) and a sucker; a large piston ( 2 ) located in the large air cavity ( 17 ); a large piston rod ( 3 ) having an air-liquid mixing cavity ( 15 ); a small piston rod ( 5 ) having a support ring ( 10 ) and a small piston base ( 11 ) a spring ( 9 ) equipped between the U-shape ring groove ( 8 ) and the supporting ring ( 10 ) to force the small piston rod ( 5 ) and large piston ( 2 ) against the large piston rod ( 3 ); a small piston 4 being slidably disposed on the small piston base ( 11 ); an over cap ( 6 ) having a nozzle, and being arranged for pumping actuation of the large piston rod ( 3 ); a first double-valve membrane arrangement including a first valve means being formed between the large piston ( 2 ) and the large piston rod ( 3 ) comprising an engagement of conical sealing surface ( 18 ) with conical opening ( 19 ) to open and close access of external air to and connecting hole 16 , and a second valve means provided between the air-liquid mixing cavity ( 15 ) and the large air cavity ( 17 ), the second valve means having a sleeve-shape valve plate ( 21 ) having a conical sealing surface ( 24 ) made of elastic material for engagement with the large piston rod ( 3 ) to open and close access of air from the large air cavity ( 17 ) to the air-liquid mixing cavity ( 15 ) through a plurality of connecting holes ( 20 ); a second double-valve membrane arrangement including a third valve means being formed by the small between the liquid cavity ( 14 ) and the air-liquid mixing cavity ( 15 ), wherein a lower end of the small piston ( 4 ) engages with a ring groove ( 12 ) on the small piston base ( 11 ) to open and close access of liquid from the liquid cavity ( 14 ) to the air-liquid mixing cavity ( 15 ) through groove ( 13 ); a foam means located in the large piston rod ( 3 ) and the over cap ( 6 ) comprising a reticulated foam base ( 25 ) having a reticulated foam meshwork ( 26 ) vertically fixed therein between a lower inlet ( 27 ) and an upper outlet ( 28 ) of the reticulated foam base ( 25 ).