A propulsion device for a syringe for mounting in a screw drive mechanism of a syringe and capable of connecting a drug cartridge, the propulsion device being assembled in the joint member by an ejector member combined with a one-way check member, the rear end of the joint member Connecting the push rod, the projecting member and the spring are arranged inside the front end of the push rod, the spiral sleeve is screwed on the outer side of the push rod, and the injection push rod is installed in the push rod, and the pushing device is loaded into the rear port of the medicine tube by the engaging member, by the medicament The spring buckle of the rear port of the cylinder presses the latch of the engaging member to be in an unlocked state, and the spring-driven projectile is ejected forward by the spring, and the projecting member is pushed forward by the projecting member to abut the piston in the drug cartridge. The syringe combined with the drug cartridge can be directly used, and the ejector member of the manually operated syringe is prevented from abutting the ejector action of the piston in the drug cartridge, thereby improving the convenience of use of the syringe.一種注射器的推進裝置，其用以裝設於注射器的螺旋驅動機構中，並能連接藥劑筒，該推進裝置係以推頂構件結合單向逆止構件組設於接合構件中，接合構件後端連接推進桿，推進桿前端內部設置彈射件與彈簧，推進桿外側螺設螺旋套環，且推進桿中裝設注射推桿，該推進裝置係以接合構件裝入藥劑筒後端口，藉由藥劑筒後端口周緣壓迫接合構件的彈扣壓抵彈射件的卡勾而呈解鎖狀態，藉由彈簧驅動彈射件朝前彈射，並利用彈射件推動推頂構件向前運動至抵接藥劑筒中的活塞，使結合藥劑筒的注射器即能直接使用，免除手動操作注射器之推頂構件向前抵接藥劑筒內的活塞的排空動作，增進注射器使用的方便性。
