Contamination-preventing device for dosing injector

The invention discloses a contamination-preventing device for a dosing injector. The contamination-preventing device is composed of a dosing injector cylinder tail lower clamping part, a dosing injector cylinder tail upper clamping part and a dosing injector piston rear handle movable clamping stopper. The dosing injector cylinder tail lower clamping part and the dosing injector cylinder tail upper clamping part are hinged through a shaft, the dosing injector piston rear handle movable clamping stopper is of a split structure, a sleeve with a bottom is arranged on the rear portion of the dosing injector cylinder tail lower clamping part, a pull rod passing hole is formed in the center of the bottom of the sleeve, a pull rod with a handle penetrates through the bottom of the sleeve from the outer portion and is connected with the dosing injector piston rear handle movable clamping stopper through a connecting pin shaft, the inner hole size of the sleeve is matched with the size of the section of the dosing injector piston rear handle movable clamping stopper, an elastic lock is installed on the dosing injector cylinder tail upper clamping part, and a lock catch matched with the elastic lock is arranged on the dosing injector cylinder tail lower clamping part.