Dispensing cartridge having an improved automatic filler stick positioning mechanism

Claim 1

In a push-up dispenser comprised of a sleeve containing a filler stick, a piston slidably arranged in said sleeve and supporting said filler stick, and a cup-shaped cover which fits over the top of said sleeve, said sleeve and said cover having coacting threaded portions, arranged on the outer surface of said sleeve and on the inner surface of said cover, the improvement which comprises: (a) sealing means located on said sleeve below the threaded portion thereof; (b) an extension of said cover below its threaded portion forming a threadfree sealing surface for sealing contact with said sealing means, the inner diameter of said sealing surface being greater than the outer diameter of said threaded portion on said sleeve; (c) the length of said sealing surface on said extension is at least approximately equal to the dimension by which the filler stick is desired to project from the opening of said sleeve in the working position; (d) said sealing means is comprised of a gasket including a base ring sealingly positioned on said sleeve and a flexible downwardly extending lip in sealing sliding contact with said sealing surface on said cover whereby said lip is pressed against said sealing surface by underpressure in the said cover created by unscrewing said cover and can lift itself from the said sealing surface in the case of overpressure under said cover; (e) the lower surface of said piston being exposed to atmospheric pressure whereby, when said cover is removed, said pressure on said lower surface of said piston together with said underpressure in said cover will move said piston and filler stick upwardly out of said sleeve to a working position.