Abstract: A multi-dose adjustable pen-injector includes a pen body, a push rod, a push rod sleeve, a clutch hub, a limiting member, and a dose hub. The push rod sleeve and the push rod are in a sliding fit with each other toward injection direction and can transmit torque for push rod. The clutch hub and the push rod sleeve are in sliding fit with each other toward injection direction. The dose hub is rotatably connected to the pen body by means of threads. Rotation between the clutch hub and the dose hub is limited by a fastening structure capable of being disengaged from the injection direction. The limiting member and the dose hub are engaged by supporting feet capable of elastically deforming toward the injection direction, thereby to simplify the product design and user operation.

Abstract: An automatic syringe, comprising: a housing, a needle guard cover, a push rod, a sounding cylinder, an inner tube, a release ring, a driving elastic member, and a resetting elastic member. During use, a needle cylinder is fixed in the housing; a needle head protrudes from the front of the housing; the needle guard cover is retractably attached to the housing; the needle guard cover can push the release ring to slide toward the rear end of the housing; after the release ring moves to the rear end, a first clip of the inner tube releases the snap-fit position-limiting of the push rod; the push rod pushes a piston under the action of the driving elastic member to inject the liquid in the needle cylinder into a part of the body to be injected, achieving automatic injection.