Patent ID: 7182226

Claim:
A dosing device having an outlet, comprising: a cover element configured to mount to a medium reservoir, said cover element having an inlet passageway providing a pathway for medium from said medium reservoir, a finite length dosing chamber of uniform dimension connected in communication with said inlet passageway, said dosing chamber having at opposite ends a dimensional widening larger in dimension than said uniform dimension of said dosing chamber; and a pump casing element mounted on said cover element and configured to move with respect thereto a defined dosing stroke length along a stroke axis, said pump casing element having an outlet chamber forming a passageway communicating with said outlet of said dosing device as well as being configured to communicate with said inlet passageway, said pump casing having an elongate plunger member longer than said finite length of said dosing chamber and having on at least a portion thereof a dimension that is conformed to said uniform dimension to operatively form a sliding piston relation with said finite length dosing chamber, said dimension of said sliding piston being less than each said dimensional widening, said sliding piston being oriented on said elongate plunger member so that at opposite ends of said stroke length, said sliding piston will be oriented beyond said uniform dimension of said dosing chamber so as to form an open passageway between said medium reservoir and said outlet chamber.