Liquid dispensing device

Claim 1

A liquid dispensing device including a housing adapted to be mounted on the top of a liquid container such as a bottle, a cylinder vertically mounted on the housing, a plunger slidably disposed in the cylinder with the upper end of the plunger projecting out of the upper end of the cylinder, a suction valve disposed in an introducing passage for introducing liquid in the container into the cylinder when the plunger moves in the upward direction, a discharge valve disposed in a discharge passage for discharging liquid in the cylinder when the plunger moves in the downward direction, and means for restricting the upward movement of the plunger, wherein the improvement comprises in that a cylindrical space having the inner diameter slightly larger than that of the cylinder is formed continuous to the lower end of the cylinder and coaxially with the cylinder, said plunger being of such length relative to said cylindrical space that said plunger extends fully into said cylindrical space at the downwardmost extent of its travel therein and whereby the resulting annular space between said cylindrical space and said plunger when the latter is in its downwardmost position within said cylindrical space is such that air in said space is substantially thoroughly exhausted therefrom in the initial downward movement of said plunger into said cylindrical space, and a normally extending transverse passage is formed to connect the inlet of the discharge valve and the upper end portion of the cylindrical space to thereby permit said thorough exhaustion of air through said passage, and wherein said suction valve and said discharge valve are respectively incorporated in a suction valve assembly and discharge valve assembly, said assemblies being threadingly and removably mounted on the housing respectively, a sleeve coaxially surrounding said cylinder and having a lower end secured to said housing, an annular cap having an annular shoulder on the inner periphery thereof is removably mounted on the upper end of said sleeve, said annular shoulder acting as a stop restricting the upward movement of the plunger, and said cap being exchangeably selected from a group of similar parts respectively having annular shoulders at respective locations so as to selectively determine the maximum stroke of the plunger.