Importance

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Abstract

A pump comprises an open-ended hollow body defining a pump chamber and an inlet orifice which communicates with a reservoir. The pump body has four side walls. A piston is mounted for reciprocal movement through a portion of the body and it extends through the upper end of the body. A ferrule is disposed above the body and defines an aperture through which the piston extends. A seal is disposed is disposed between the ferrule and the body, and the seal surround a portion of the piston. A spring is mounted in the body, and the spring actively biases the piston toward the top of the body. The body has a deformable zone which has at least a portion of one side wall which is a noncircular cross-section and is radially elastically deformable. The piston has a portion which blocks the inlet orifice when the piston is depressed a first predetermined distance. The piston has an evacuation duct having a lower duct portion extending through the periphery of the piston which puts the pump chamber in communication with ambient air when the piston is depressed a second predetermined distance sufficient for the lower duct portion to be lower than the seal, the second predetermined distance being greater then the first predetermined distance. The lower duct portion is located sufficiently high on the piston so as to delay the placing of the pump chamber into communication with ambient air by the evacuation duct until after the piston is depressed into the body the second predetermined distance which is sufficiently in excess of the first predetermined distance so as to pressurize the pump chamber and radially elastically deform the deform the deformable zone.

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First Claim