Dispenser for patient infusion device

A device for delivering fluid, such as insulin for example, to a patient. The device includes an exit port assembly, a syringe-like reservoir including a side wall extending towards an outlet connected to the exit port assembly. A threaded lead screw is received in the reservoir and a plunger has an outer periphery linearly slideable along the side wall of the reservoir and an inner periphery threadedly received on the lead screw. The plunger is non-rotatable with respect to the side wall such that rotating the lead screw causes the plunger to advance within the reservoir and force fluid through the outlet. The device also includes a dispenser having a return element for causes rotation of the lead screw, and a shape memory element. A changeable length of the shape memory element decreasing from an uncharged length to a charged length resets the return element.