| 摘要 |
An injection device (210; 110) is described. A housing (212; 112) receives a syringe and includes a return spring (226; 126) for biasing the syringe from an extended position in which its needle (218; 118) extends from the housing (212; 112) to a retracted position in which the it does not. A drive spring (230; 130) acts on a first drive element (232; 132) and a second drive element (234; 134) acts upon the syringe to advance it from its retracted position to its extended position and discharge its contents through the needle. The first drive element (232; 132) is capable of movement relative to the second (234; 134) once a nominal decoupling position has been reached. A release mechanism is activated when the first drive element (234; 134) is further advanced to a nominal release position, to release the syringe (214; 114) from the action of the drive spring (230; 130), whereupon the return spring (226; 126) restores the syringe (214; 114) to its retracted position. The nominal decoupling and release positions are defined relative to the syringe (214; 114). This may be achieved by interaction between a moving component and a decoupling component (162; 262) that moves with the syringe as it is advanced. |
