Patent ID: 8936574
Filing Date: 2015-01-20
Classification: A61M,F04B

Abstract:
1. A drive system used to dispense a liquid drug from a drug container having a piston, said drive system comprising: a lead screw having a rotational axis and operably connected to the piston; a ratchet wheel provided along the rotational axis and operably connected to the lead screw to move the lead screw; a piezoelectric motor having a shaft, a first nut engaging the shaft, and piezoelectric elements configured to produce reciprocating linear motion of the shaft relative to the first nut adjacent the rotational axis, wherein the shaft of the piezoelectric motor is situated perpendicular to the rotational axis and is connected to a rocker; and a pawl operably connected to the shaft and engaging the ratchet wheel such that the reciprocating linear motion of the shaft is converted into unidirectional rotary motion of the ratcheted wheel about the rotational axis which moves the lead screw and advances the piston to dispense the liquid drug from the drug container.