A rotary pump is presented for use in a medicament delivery device, where the pump has a back plate having an inner surface and a rotor housing is positioned adjacent to the back plate having a peripheral wall. A front plate support is connected to the back plate and a flexible front plate is positioned between the front plate support and the rotor housing. The pump is rotated using a planetary gear transmission, where an eccentric shaft is operatively connected to the planetary gear mechanism. A rotor is rotationally fixed to the eccentric shaft and movably positioned within rotor housing. The rotor has three lobes, where each lobe has two peripheral curved surfaces sharing a common apex, where a first portion of each peripheral surface adjacent to the apex defines a non-smooth curve.本發明提出用於一藥劑遞送裝置中之一旋轉泵，其中該泵具有擁有一內表面之一背板，且具有一周邊壁之一轉子殼體鄰近於該背板定位。一前板支撐件連接至該背板且一可撓性前板定位於該前板支撐件與該轉子殼體之間。該泵係使用一行星齒輪傳動裝置旋轉，其中一偏心軸桿可操作地連接至該行星齒輪機構。一轉子旋轉地固定至該偏心軸桿且可移動地定位於轉子殼體內。該轉子具有三個葉瓣，其中各葉瓣具有共用一共同頂點之兩個周邊彎曲表面，其中各周邊表面之鄰近於該頂點之一第一部分界定一非平滑曲線。
