Patent ID: 8202250

Claim:
A delivery device for delivering an infusion medium to a user, the device comprising: a first housing portion adapted to be secured to a user; a second housing portion configured to be selectively engaged with and disengaged from the first housing portion to allow disposal of the first housing portion without disposing of the second housing portion, the second housing portion having an enclosed interior volume; a drive shaft supported by the second housing portion, for movement in a generally linear dimension; a drive device operatively connected to the drive shaft, to selectively move the drive shaft in the generally linear dimension; and a pump device supported by the first housing portion, the pump device comprising: a housing provided with a piston channel having a generally linear, longitudinal axis dimension, an inlet port in fluid flow communication with the channel and configured for connection to a reservoir, and an outlet port in fluid flow communication with the channel and configured for connection in fluid flow communication with an injection site; a piston located in the piston channel and having a first piston section and a second piston section coupled together for limited movement, relative to each other, the first and second piston sections are spaced from each other in the longitudinal axis dimension of the piston channel, arranged external to each other and end-to-end, and moveable toward and away from each other along the longitudinal axis dimension of the piston channel, and the second piston section having a surface for operable engagement with the drive shaft when the second housing portion and first hosing housing portion are engaged, wherein the piston is moveable with movement of the drive shaft along the longitudinal axis dimension of the piston channel between fill, pull and dispense positions, such that: in the fill position, the first and second piston sections are separated and spaced apart from each other in the longitudinal axis dimension of the piston channel to form a chamber having volume between the first and second piston sections, and the chamber is aligned in fluid flow communication with the inlet port; in the pull position, the first and second piston sections are separated and spaced apart from each other in the longitudinal axis dimension of the piston channel and the chamber formed between the first and second piston sections is located within the channel, between the inlet port and the outlet port, out of fluid flow communication with the inlet port and the outlet port; in the dispense position, the chamber between the first and second piston sections is aligned in fluid flow communication with the outlet port.