Sanofi
DRIVE TRAIN FOR DIAL OF A TORSION-SPRING ASSISTED WIND-UP INJECTION DEVICE

Abstract:

A drive train (T) for a wind-up injection device (1) for injecting a liquid drug comprises a torsional energy storage (9) adapted to be loaded or unloaded by a rotatable element (6), a rotatable user handle (8), a rotationally driveable expelling mechanism (5) adapted to expel the liquid drug and a clutch element (12) coupled with the torsional energy storage (9) via the rotatable element (6) and comprising a ratchet (12.4) for maintaining the rotatable element (6) at one of a number of discrete angular positions against the torque of the torsional energy storage (9). The clutch element (12) is adapted to transmit a torque from the user handle (8) via the rotatable element (6) to the torsional energy storage (9) or alternatively from the torsional energy storage (9) via the rotatable element (6) to the expelling mechanism (5), wherein the ratchet (12.4) is switchable from one position to an adjacent position by a torque transmitted from the user handle (8) to the torsional energy storage (9). The drive train (T) is adapted to dampen torque peaks visco-elastically and/or visco-frictionally.