Single-screw pump and packaging type mechanical sealing device used for single-screw pump

The utility model belongs to the technical field of screw pumps, particularly discloses a single-screw pump and a packaging type mechanical sealing device used for the single-screw pump, and aims to improve the assembly efficiency when the packaging type mechanical sealing device is applied to the single-screw pump. According to the packaging type mechanical sealing device, the working length positioning groove is formed in the shaft sleeve, the detachable limiting piece is arranged in the working length positioning groove, and meanwhile the spring seat, the spring, the movable ring assembly and the static ring assembly are arranged between the shaft shoulder and the limiting piece, so that the spring is in a pre-tightening state; then the static ring assembly and the limiting piece are detachably connected to be pre-fixed, and therefore it is guaranteed that the pre-assembled packaging type mechanical sealing device is in the good working length; when the integrated mechanical sealing device is applied to th