Syringe with retractable needle

Syringe with a retractable needle comprising

• a barrel (2) having a nozzle (19) integrated in a male Luer adapter element;
• a piston (3) slidably arranged in the barrel (2) and coupled to a sealing element (16), said sealing element (16) having a central channel (20);
• a needle assembly comprising a needle (4), a needle holder (6) and a female Luer adapter element (7);
• a spring assembly arranged in the piston (3) comprising a spring sleeve (12), a spring (13) mounted on the spring sleeve (12), a spring tensioning element (14) located on the spring sleeve (12) and held in position by the piston wall, and a plunger (15) mounted within the spring sleeve (12);
• and
• a piston cap (10);
• said piston (3) being coupled to the sealing element (16) by means of the spring tensioning element (14);
• said spring sleeve (12) being held in position within the piston (3) by a ring element (18) protruding from the inner wall of the piston (3) and supporting the proximal end of the spring sleeve (12), the spring sleeve (12) extending into the channel (20) of the sealing element (16) to the distal end thereof;
• said spring sleeve (12) comprising at its distal end a circular protrusion (21) on the inside designed to engage a circular recess (22) at the proximal end of the needle holder (6);
• wherein the spring sleeve (12) comprises an outer flange (17) supporting the proximal end of the spring (13) and comprises a widened section (46a) adjacent to the outer flange (17) for securing the proximal end of the spring (13);
• wherein upon exertion of pressure to the piston (3) in its advanced position results in the engagement of the spring sleeve (12) and the needle holder and the release of the spring (13) sleeve thus actuating the spring and retracting the needle holder (6) and the needle (4), wherein the piston (3) comprises a holding ring (11) on its inner surface in the proximal part of the piston;
• wherein the holding ring is designed to engage with the outer flange (17) of the spring sleeve (12) where, after actuation of the spring (13) the reaction mechanism stays locked;
• and
• wherein the spring element (13) is a compression spring comprising closed ring elements at the ends where spring windings form parallel double rings (46) that run perpendicular to the centerline of the spring (13) and are seated on and held by the widened section.