Combination container and pump having a conical piston for venting

Claim 1

A combination container and pump comprising: a cylindrical container for storing a liquid, said cylindrical container having first and second axial ends; a pump mounted in said first axial end, for drawing the liquid stored in said cylindrical container and discharging the drawn liquid out of said cylindrical container; a piston slidably disposed in said second axial end for keeping the liquid sealed in said cylindrical container, said piston being movable toward said pump as the amount of the liquid stored in said cylindrical container is reduced when the liquid is discharged from the cylindrical container by said pump; said piston having a conical surface facing said pump for contact with the liquid stored in said cylindrical container, said conical surface projecting toward said first axial end and having a shape complementary to the shape of an inner surface of said first axial end of said cylindrical container, said piston also having a cylindrical surface defining a communication hole defined axially therethrough and having an inner end opening at said conical surface, said communication hole providing communication between the interior and the exterior of said cylindrical container, said piston having at least one radial slot therein extending from said conical surface to said communication hole, said radial slot having a slanted surface inclined progressively toward said second axial end in a direction opposite to said conical surface; and a cap comprising a cap body inserted in said communication hole and a flange closing an outer end of said communication hole, at least either one of said cap body and said cylindrical surface having at least one groove extending along the direction in which said cap body is inserted into said communication hole.