Patent ID: 8528792
Filing Date: 2013-09-10
Classification: B05B

Abstract:
1. A pump for dispensing fluids from a reservoir, comprising: a piston chamber-forming member having an elongate chamber, said chamber having a chamber wall, an outer open end and an inner end in communication with the reservoir; a one-way valve between the reservoir and the chamber permitting fluid flow through the inner end of the chamber, only from the reservoir to the chamber; a piston-forming element slidably received in the chamber extending outwardly from the open end thereof; the piston-forming element having an inner head portion, an outer base portion and a variable length portion intermediate the head portion and the base portion joining the head portion and the base portion, a head disc extending radially outwardly from the head portion, the head disc having an edge portion proximate the chamber wall circumferentially thereabout, the edge portion of the head disc engaging the chamber wall circumferentially thereabout to substantially prevent fluid flow in the chamber past the head disc in an inward direction, the head disc elastically deforming away from the chamber wall to permit fluid flow in the chamber past the head disc in an outward direction, the base portion having a central axially extending hollow stem having a central passageway open at an outer end forming an outlet, a base disc extending radially outwardly from the stem of the base portion axially outwardly from the head disc, the base disc having an edge portion proximate the chamber wall circumferentially thereabout, the edge portion of the base disc engaging the chamber wall circumferentially thereabout to substantially prevent fluid flow in the chamber past the base disc in an inward direction, the passageway extending from the outlet inwardly to an inner end open to the chamber between the head disc and the base disc, the variable length portion having an axial length measured between the head disc and the base disc which is variable between a maximum length and a minimum length, wherein when the variable length portion has the maximum length the variable length portion is in an expanded condition and when the variable length portion has the minimum length the variable length portion is in a compressed condition, the piston-forming element received in the piston chamber-forming member reciprocally coaxially-slidable inwardly and outwardly by movement of the base portion in the chamber between a retracted position and an extended position in a cycle of operation to draw fluid from the reservoir and dispense it from the outlet, wherein in movement of the base portion inwardly in the chamber while the length of the variable length portion is greater than the minimum length, resistance to movement of the head disc inwardly in the chamber is sufficient that the length of the variable length portion decreases toward the minimum length before the head portion is substantially moved inwardly in the chamber, in movement of the base portion outwardly in the chamber while the length of the variable length portion is less than the maximum length, resistance to movement of the head disc outwardly in the chamber is sufficient that the length of the variable length portion increases toward the maximum length before the head portion is substantially moved outwardly in the chamber, and movement of the base portion outwardly in the chamber while the length of the variable length portion increases toward the maximum length draws fluid in the passageway back into the chamber; the chamber is coaxially disposed about a chamber axis with the chamber wall substantially circular in any cross section normal to the axis; the variable length portion comprises an elongate member coupled at an outer end to the base portion and at an inner end to the head portion, the elongate member transmitting axially directed tension force applied thereto by the base portion from the base portion to the head portion, the elongate member reducing in length axially between the base portion and the head portion when axially directed compression forces are applied to the elongate member by the base portion; the elongate member comprises a resilient member haying an inherent bias to assume an unbiased configuration having an unbiased length measured alone the chamber axis equal to or less than the maximum length, the resilient member resiliently deflectable to biased configurations each having a length equal to or less than the maximum length, the inherent bias of the resilient member biasing the resilient member to return towards the unbiased configuration from any one of the biased configurations.