Abstract: A locking structure for an injection pen. The locking structure for an injection pen is disposed among a spiral duct (30), a push rod (81) and a propelling lever (60) of a circularly-pushing device (1) of the injection pen. The propelling lever (60) penetrates in a tube center hole (331) of a linkage wall (33) in the spiral duct (30) by means of a dosage control section (63) having a push thread (631). The push rod (81) penetrates in the propelling lever (60) by means of a rod portion (811). The locking structure comprises a necking ring portion (36), a buckling recessed portion (814), and an elastic clasp (612). The necking ring portion (36) is formed at the rear side surface of the linkage wall (33) in the spiral duct (30). The buckling recessed portion (814) is formed in the front section of the rod portion (811) of the push rod (81). The elastic clasp (612) is formed in the rear end of the propelling lever (60) adjacent to the dosage control section (63).

Abstract: An injection pen comprises a circularly pushing device (1) and a vial housing (2), and is used to combine a medication vial (3) with a needle (4). The circularly pushing device (1) comprises a jointing member (10), a spiral sleeve (20), a spiral duct (30), a spirally-pushing tube (40), a threaded-connection shrink-ring (50), a propelling lever (60), a one-way ratchet ring (70), and an injection operation member (80). During the injection, the one-way ratchet ring (70) on a push rod (81) is jointed with a one-way ratchet groove portion (46) of the spirally-pushing tube (40) so as to restrain the rotation directions of the push rod (81) and the spirally-pushing tube (40); the propelling lever (60) cannot be rotated due to the limit of the jointing member (10).

Abstract: A syringe is applied to connect with a vial and a needle, and the syringe includes an outer protecting housing, a connecting ring, a vial housing, an inner tube, a bidirectional guiding tube device, a screwing sleeve, a ratchet, a spiral rotating rod and an injection rod unit. The connecting ring is mounted on a front end of the outer protecting housing, and the vial housing is connected with the connecting ring for assembling a vial. The inner tube, the bidirectional guiding tube device, the screwing sleeve, the ratchet, the spiral rotating rod and the injection rod unit are mounted in the outer protecting housing. The injection rod unit is rapidly pulled backward and then is pressed to move forward for injecting.