Manual control dispensing pump for liquid containers

Claim 1

A reciprocating manual dispensing pump comprising: a body having a single pumping cylinder section; a suction valve at one end of said pumping cylinder section; a hollow piston, said piston further comprising: a smaller diameter section operating within and slidingly sealed at one end to the walls of said pumping cylinder, said smaller diameter section being of a length equal to the maximum reciprocating stroke of said pump; a larger diameter section composed of resiliently deformable material and having upper and lower walls defining an internal chamber hydraulically connected to said smaller diameter section, said upper and lower walls being connected to one another, said lower wall being attached to said smaller diameter section at the end of said smaller diameter section opposite said slidingly sealed end; an outlet tube extending from said upper end of said larger diameter section in the direction opposite said smaller diameter section; a valve projection on the inner surface of said lower wall, said projection being located opposite to said outlet tube, said projection being of sufficient length and diameter to close the opening to said outlet tube when the larger diameter section is undeformed, whereby said outlet is closed until internal pressure displaces said projection by deformation of said chamber; and a spring within said pumping cylinder section, said spring providing a restoring force to said piston.