Disposable injection needle

A disposable injection needle, comprising:

• a needle seat provided with a needle tube extending axially therethrough and having a first end and a second end;
• a shell, a second end of the shell being connected to the second end of the needle seat to form an accommodating space between the shell and the needle seat, and a first end of the shell having a second opening;
• an inner sheath, a second end of the inner sheath being located within the accommodating space, a first end of the inner sheath having a first opening and being adapted to extend out of the second opening, and a portion of the inner sheath being axially slidable within the accommodating space;
• an inner core, a second end of the inner sheath being sleeved on a first end of the inner core, wherein the first end of the inner core comprises a third opening for the first end of the needle tube to extend through;
• a second spring disposed between the inner core and the first end of the needle seat and adapted to provide an elastic force for axially moving the inner core and the inner sheath together outward from the accommodating space;
• a tail sheath disposed at the second end of the needle seat and having a tail sheath hole for the needle tube to pass through, wherein the tail sheath comprises an extension member extending substantially in an axial direction, and the tail sheath has a first axial position and a second axial position along the axial extension direction, wherein in the first axial position, the second end of the needle tube is exposed from the tail sheath hole, and in the second axial position, the second end of the needle tube is not exposed from the tail sheath hole;
• a first spring disposed between the needle seat and the tail sheath to provide power for the tail sheath to move from the first axial position toward the second axial position;
• wherein:
• the inner core has a first circumferential position and a second circumferential position, wherein before the injection needle is used, the inner core is in the first circumferential position where the inner core fittingly abuts against the extension member in the axial direction, and after the injection needle is used, the inner core is in the second circumferential position where the inner core is disengaged from the extension member in the axial direction;
• and
• based on the inner core rotating from the first circumferential position to the second circumferential position, the tail sheath is adapted to move from the first axial position toward the second axial position under the action of the first spring.