Safety system for a syringe

1. An assembly comprising a safety support device for a syringe and a syringe having a body presenting a collar, a piston, and a needle, the device comprising

a support sheath for the syringe body and

safety means comprising an inner sheath capable of sliding relative to the support sheath between a waiting, retracted position in which the inner sheath is substantially retracted inside the support sheath and is suitable for being placed around at least an end portion of the syringe body carrying the needle, and a protective, extended position in which the inner sheath projects beyond the support sheath to provide protection around the needle,

the device further comprising retaining means suitable for being activated to retain the inner sheath in the waiting, retracted position inside the support sheath and for being deactivated to allow the inner sheath to be extended under drive from a thrust means, wherein the retaining means comprise resilient tongues and retaining surfaces, said tongues being integral with the inner sheath, said retaining surfaces formed on an inner periphery of the support sheath, the tongues being retained on the retaining surfaces in their active, retaining configuration, and being suitable for being moved resiliently towards their inactive configuration in which they escape from said surfaces,

wherein the resilient tongues are oriented substantially axially, and co-operate in their active configuration with said retaining surfaces, and

wherein the resilient tongues present free ends which extend through passages formed between the collar of the body of the syringe and the inner periphery of the support sheath, and wherein the piston of the syringe further comprises an actuation head suitable for cooperating with the free ends of the tongues to urge the tongues towards their inactive position,

the collar being held motionless against an abutment so as to maintain the syringe body fixed inside said support sheath, and the retaining means being suitable for being activated as a function of the position of the piston of the syringe, while the body of the syringe remains fixed inside the support sheath.

2. An assembly according to claim 1 , wherein the support sheath has a rear end portion and a main portion, said rear portion presenting holding means for the collar of the body of the syringe and a bearing surface for the thrust means.

3. An assembly according to claim 2 , wherein the support sheath, the inner sheath, and the thrust means form a unit in which the syringe body can be inserted by axial thrust until the collar of said body co-operates with said holding means.

4. An assembly according to claim 1 , wherein the inner periphery of the support sheath further comprises a shoulder on which there are formed both an abutment surface for the collar of the syringe and the retaining surfaces for the resilient tongues.

5. An assembly according to claim 1 , wherein the safety support device further comprises locking means suitable for locking the inner sheath in its protective, extended position.

6. An assembly according to claim 5 , wherein the locking means comprises a locking surface formed on the inner periphery of the support sheath and at least one locking element integral with the inner sheath and suitable for co-operating with said locking surface when the inner sheath is in the protective, extended position.

7. An assembly according to claim 6 , wherein the resilient tongues also constitute locking elements suitable for co-operating with the locking surface when the inner sheath is in the protective, extended position.

8. An assembly according to claim 1 , wherein the thrust means comprise a spring placed around the body of the syringe and bearing against a first bearing surface belonging to one of the elements constituted by the syringe body and by the support sheath, and against a second bearing surface belonging to the inner sheath.

9. An assembly according to claim 1 , wherein the safety support device further comprises holding means suitable for holding motionless the syringe body relative to the support sheath, said holding means comprising said abutment and a snap-fastening edge formed on the support sheath between which the collar is suitable for being held motionless.

10. An assembly comprising a safety support device for a syringe and a syringe having a body presenting a collar, a piston, and a needle, the device comprising

a support sheath for the syringe body and

safety means comprising an inner sheath capable of sliding relative to the support sheath between a waiting, retracted position in which the inner sheath is substantially retracted inside the support sheath and is suitable for being placed around at least an end portion of the syringe body carrying the needle, and a protective, extended position in which the inner sheath projects beyond the support sheath to provide protection around the needle,

the device further comprising retaining means suitable for being activated to retain the inner sheath in the waiting, retracted position inside the support sheath and for being deactivated to allow the inner sheath to be extended under drive from a thrust means,

wherein the support sheath has a rear end portion and a main portion, said rear portion presenting holding means for the collar of the body of the syringe and a bearing surface for the thrust means and

wherein the support sheath, the inner sheath, and the thrust means form a unit in which the syringe body can be inserted by axial thrust until the collar of said body co-operates with said holding means,

wherein the retaining means comprise resilient tongues and retaining surfaces, said tongues being integral with the inner sheath, the tongues being retained on the retaining surfaces in their active, retaining configuration, and being suitable for being moved resiliently towards their inactive configuration in which they escape from said surfaces;

the collar being held motionless against an abutment so as to maintain the syringe body fixed inside said support sheath, and the retaining means being suitable for being activated as a function of the position of the piston of the syringe, while the body of the syringe remains fixed inside the support sheath.

11. An assembly according to claim 10 , wherein the safety support device further comprises locking means suitable for locking the inner sheath in its protective, extended position.

12. An assembly comprising a safety support device for a syringe and a syringe having a body presenting a collar, a piston, and a needle, the device comprising

a support sheath for the syringe body and

safety means comprising an inner sheath capable of sliding relative to the support sheath between a waiting, retracted position in which the inner sheath is substantially retracted inside the support sheath and is suitable for being placed around at least an end portion of the syringe body carrying the needle, and a protective, extended position in which the inner sheath projects beyond the support sheath to provide protection around the needle,

the device further comprising retaining means suitable for being activated to retain the inner sheath in the waiting, retracted position inside the support sheath and for being deactivated to allow the inner sheath to be extended under drive from a thrust means,

wherein the retaining means comprise resilient tongues and retaining surfaces, said tongues being integral with the inner sheath, the tongues being retained on the retaining surfaces in their active, retaining configuration, and being suitable for being moved resiliently towards their inactive configuration in which they escape from said surfaces,

wherein the resilient tongues also constitute locking elements suitable for co-operating with a locking surface formed on an inner periphery of the support sheath when the inner sheath is in the protective, extended positions,

the collar being held motionless against an abutment so as to maintain the syringe body fixed inside said support sheath, and the retaining means being suitable for being activated as a function of the position of the piston of the syringe, while the body of the syringe remains fixed inside the support sheath.