Patent ID: 7770874
Filing Date: 2010-08-10
Classification: A47K,B05B,B65D

Abstract:
1. A pump for dispensing liquid from a reservoir comprising: a piston-chamber forming member, a piston forming element received in the piston-chamber forming member coaxially axially slidable about a longitudinal axis inwardly and outwardly therein between an inward retracted position and an outward extended position, said piston forming element having a central axially extending stem having a central passageway, an inner end, an outer end and an outlet proximate the outer end of the stem extending out of the piston-chamber forming member and from which liquid is dispensed, at least one annular chamber formed annularly about the stem between the piston forming element and the piston-chamber forming member providing for controlled movement of liquid from the reservoir into the annular chamber and for dispensing of liquid in the annular chamber to the outlet with reciprocal sliding of the piston forming element between the retracted position and the extended position, a spring extending from a first end to a second end about the axis, the spring having an inherent bias to assume an extended position with the first end spaced from the second end along the axis, the spring assuming compressed positions when compressed by forces applied parallel to the axis, in the compressed positions the spring resiliently urges its first and second ends axially away from each other toward the extended position; the spring having a wall in the shape of a solid of revolution rotated about the axis and defining a central cavity therein open at the first end of the spring and substantially closed at the second end of the spring, the wall of the spring when in the unbiased extended position having a greatest diameter at the first end and a least diameter at the second end, a plurality of openings through the wall of the spring, each of the plurality of openings disposed symmetrically both circumferentially and axially relative to each other, the second end of the spring coupled to the inner end of the stem of the piston forming element, the first end of the spring coupled to an inner end of the piston-chamber forming member, the spring extending inwardly from the inner end of the stem of the piston forming element coaxially relative the piston forming element from the second end of the spring to the first end of the spring wherein said first end of the spring is coupled to the inner end of the piston-chamber forming member, the spring member being axially compressed with reciprocal sliding of the piston forming element from the extended position to the retracted position, the inherent bias of the spring urging the piston forming element axially from the retracted position toward the extended position, the piston-chamber forming member including a spring housing, the spring housing located coaxially surrounding the spring with the spring disposed internally within the spring housing, the spring housing having a side wall with an inner, first end and an outer, second end, the side wall disposed radially outwardly of the wall of the spring circumferentially entirely thereabout, the first end of the spring fixedly coupled to a first end of the side wall of the housing with the side wall of the housing extending axially from the first end of the spring coaxially about the spring outwardly towards the second end of the spring, the second end of the spring housing fixedly coupled to the outer an of the piston chamber-forming member, wherein in deflection of the spring with relative movement of the piston forming element and the piston-chamber forming member from the extended position to the retracted position, the side wall of the housing disposed radially outwardly of the wall of the spring such that the side wall of the housing prevents deflection of the wall of the spring radially outwardly therepast to assist in maintaining the spring coaxial relative to the housing.