Fluid dispensing pump having axially deformable valve

A fluid dispensing pump comprising:

• a housing adapted to be connected to a container holding a fluid to be dispensed, said housing defining interiorly thereof a generally cylindrical bore having (1) a fluid inlet port in the axial inner end wall thereof for communication with the container, (2) a fluid outlet port opening through a side wall thereof, and (3) an open axially outer end;
• a generally cylindrical barrel received within the open outer end of said bore, the axially inner end wall of the barrel being spaced from the axially inner end wall of the bore to define therebetween a generally cylindrical valve chamber, said barrel defining interiorly thereof a generally cylindrical pumping chamber having (1) at least one opening through the axially inner end wall thereof for communicating with the valve chamber and (2) an open axially outer end;
• a generally cylindrical piston received within the open outer end of said pumping chamber for reciprocation therein between an axially outer position and an axially inner position;
• resilient means for returning said piston to said axially outer position;
• a resilient, generally cylindrical valve member located in said valve chamber and having (1) an axial passageway therethrough for establishing fluid communication between the inlet port in the housing and said pumping chamber and (2) a generally circular sealing lip on the axially outer end wall thereof for establishing, in the relaxed state of said valve member, a fluid-tight seal with the axially inner end wall of the barrel in surrounding relation to said at least one opening therethrough, said valve member being axially deformable from said relaxed state in response to the build up of fluid pressure within said pumping chamber by reciprocation of said piston to an inwardly deflected state at which said sealing lip is at least partially out of engagement with the inner end wall of the barrel, thereby permitting fluid flow from the pumping chamber to the outlet port;
• and
• check valve means for (1) closing the passageway through the valve member upon inward movement of the piston and (2) opening said passageway to permit fluid flow therethrough upon outward movement of the piston.