The invention provides an injection device for delivering a dose of medicament from a syringe. The injection device comprises a housing, a plunger moveably mounted within the housing an actuation mechanism arranged to provide a forward biasing force to urge the plunger forward in use to express a dose of medicament and a trigger mechanism arranged to (directly or indirectly) releaseably hold the plunger against the force of the actuation mechanism. The injection device further comprises a plunger velocity regulator comprising a cam surface associated with one of the housing or the plunger, and a cam member associated with the other of the plunger or the housing and arranged to engage the cam surface during actuation movement of the plunger such that axial movement of the plunger relative to the housing causes relative rotational movement of the cam member and limits the forward velocity of the plunger movement.本發明提供一種注射裝置，用於輸送自一注射器來的一劑量藥劑。該注射裝置包含一殼體；一柱塞，可移動地安裝於該殼體中；一啟動機構，設置以在使用中提供一向前偏壓力以將該柱塞推向前來擠壓一劑量藥劑；一觸發機構，設置以(直接或間接)可釋放地夾持該柱塞，以對抗該啟動機構的力。該注射裝置更包含一柱塞速度調整器，包含一凸輪表面，與該殼體或該柱塞的一者連接；以及一凸輪構件，在柱塞的啟動移動期間與該柱塞或該殼體的另一者連接，以接合該凸輪表面，以使該柱塞相對於該殼體軸向移動，造成該凸輪構件的相對旋轉移動，並限制該柱塞移動的向前速度。
