The present invention relates to a drive mechanism suitable for injection devices, in particular pen-type drug delivery devices, and to such drug delivery devices. The mechanism connects the driven member (120) that can be driven by a spring, the driven member (40) that can be rotated, and the driven member (40) and the driving member (120) in a connected state in the rotational direction. The clutches (41, 121) and the clutches (41, 121), which enable the relative rotation in the clockwise and counterclockwise directions of the driven member (40) and the driving member (120) in the decoupling state, are brought into the connected state. A spring that allows relative axial movement of the driven member (40) and the driven member (40) that urges and decouples the clutch (41, 121) against the bias of the spring (130) (130). The clutch includes a first ring of crown teeth (121) of the drive member (120) and a second ring of corresponding crown teeth (41) of the driven member (40), each crown tooth (41, 121) have different ramp tooth angles in the clockwise and counterclockwise directions, and the teeth (41, 121) can ride on each other with different resistances in the clockwise and counterclockwise directions when the clutch is decoupled. It is like that. The material of the driving member (120) may be polybutylene terephthalate (PBT) or polyoxymethylene (POM), and the material of the rotatable driven member (40) is PBT, POM, or polycarbonate (PC). It may be. Further, the coefficient of friction (μ) between the teeth (41, 121) may be 0.07 to 0.13, and the teeth (41, 121) have a surface roughness (Ra) of 0.5 to 1.2. You may have.本発明は、注射デバイス、特にペン型薬物送達デバイスに適した駆動機構、およびそのような薬物送達デバイスに関する。機構は、ばね駆動の回転可能な駆動部材（１２０）と、回転可能な被駆動部材（４０）と、連結状態で被駆動部材（４０）と駆動部材（１２０）とを回転方向に連結し、デカップリング状態で被駆動部材（４０）と駆動部材（１２０）との時計方向および反時計方向への相対回転を可能にするクラッチ（４１、１２１）と、クラッチ（４１、１２１）を連結状態に付勢し、ばね（１３０）の付勢に対抗してクラッチ（４１、１２１）のデカップリング状態にする駆動部材（１２０）と被駆動部材（４０）との相対軸方向運動を可能にするばね（１３０）とを含む。クラッチは、駆動部材（１２０）のクラウン歯（１２１）の第１のリングと、被駆動部
