Pen-type injection device with multi-piece telescopic piston rod configuration

The present disclosure provides driver components and methods of operating the same that provide reduced dimensional specifications for pen injection devices. In particular, various multi-piece telescopic piston rod configurations are disclosed that may be implemented within a pen-type injection device to achieve such improvements. The driver component replaces a single piston rod having a fixed length with a telescoping member controlled to extend at least partially axially to dispense fluid from a reservoir or cartridge. 本公开提供了驱动器部件及其操作方法，其为笔式注射装置提供了减小的尺寸规格。特别地，公开了各种多件式伸缩活塞杆构造，多件式伸缩活塞杆构造可实施在笔式注射装置内，以实现此类改进。驱动器部件用伸缩件代替具有固定长度的单个活塞杆，该伸缩件被控制成至少部分地轴向延伸，以从贮存器或筒中分配流体。