WO2002070055A1

WO2002070055A1 - Syringe or similar device

Info

Publication number: WO2002070055A1
Application number: PCT/FR2002/000792
Authority: WO
Inventors: Laurent Barrelle; Hubert Jansen
Original assignee: Becton Dickinson France
Priority date: 2001-03-05
Filing date: 2002-03-05
Publication date: 2002-09-12
Also published as: FR2821560A1; FR2821560B1; WO2002070054A1; FR2821561A1; FR2821561B1

Abstract

The invention relates to a syringe comprising a syringe barrel and a ring (6) which is connected to the proximal end of said syringe barrel. According to the invention, - the ring (6) comprises two diagonally opposite holding parts (47) intended to receive and hold the syringe barrel between them; each holding part (47) is in the form of a fork, i.e. comprising a pair of arms (55) and a connecting body (56) which connects said arms (55) to the ring (6), the shape of the arms (55) of each holding part (47) being such that said arms can partially encircle the syringe barrel; and the arms (55) are made from a material having a degree of elastic flexibility such that said arms can be elastically deformed in order to receive and clasp between them syringe barrels (2) having different external diameters.

Description

SYRINGE, OR SIMILAR DEVICE

The present invention relates to a syringe, or similar device.

A syringe sometimes includes a syringe body to be connected, on the proximal side, to a ring.

Existing rings, however, have the main drawback of not being able to receive syringe bodies of different diameters. However, syringe bodies of different diameters are used according to needs, and these existing syringes cannot therefore be adapted to these specific needs.

These existing syringes also have various drawbacks linked either to their relative structural complexity, or to manufacturing problems resulting from the dimensional tolerances of their constituent parts or the assembly tolerances of these parts, or to the existence of clearances between said parts. .

The present invention aims to remedy all of these drawbacks.

Its main objective is therefore to provide a syringe capable of receiving syringe bodies of different diameters, so that this syringe can include standardized parts and receive different syringe bodies, as required.

Another objective of the invention is to achieve the objective indicated above without overly complicating the structure or the assembly of the syringe, or even by simplifying this structure and this assembly in relation to existing syringes.

The syringe concerned comprises a syringe body and a ring to which the syringe body is connected on the proximal side. According to the invention,

- The ring has at least two holding parts, for example diametrically opposite, intended to receive and hold together the syringe body; each retaining part has a fork shape, that is to say comprises a pair of arms and a connecting body connecting these arms to the ring, the arms of each retaining part being shaped so as to be able to partially surround the syringe body; and - said arms are made of a material having a degree of elastic flexibility such that they can be elastically deformed so to be able to receive therebetween, and enclose, syringe bodies of different outside diameters.

The syringe according to the invention can thus comprise a standardized ring capable of receiving syringe bodies of different external diameters, as required.

The syringe may in particular comprise two holding parts, diametrically opposite.

Each of the arms of a holding part can comprise at least one boss projecting radially inwards, to ensure the immobilization, and possibly the centering, of a syringe body of a reduced diameter.

A chamfer can be arranged in said arms on the side of the ring by which a syringe body is intended to be introduced through this ring. This chamfer thus makes it possible to facilitate the engagement of a syringe body between said arms.

Advantageously, the syringe comprises:

a protective case, engaged around the syringe body, this case and this body being movable relative to one another between a position of use of the device, in which the needle of the syringe is exposed, and a safety position, in which this needle is surrounded by the case so as to prevent any risk of puncture or cutting, and therefore possible contamination, of the user, after use; the protective case comprises at least one light or longitudinal groove; - The ring forms a means of displacement of the syringe body and the protective case relative to each other between said positions of use and safety, and has for this purpose a part housed inside of the protective case, comprising said retaining parts, and at least one support grip part, engaged through said lumen or groove and protruding beyond the protective case, which is used for taking pressing the index or middle finger of the user's hand;

- The piston rod of the syringe comprises two telescopic parts, one of which, distal, is connected to the piston of the syringe, and the other, proximal, has a head forming a support grip part for the thumb of the 'user; and at least one breakable bridge connects the two telescopic parts of the piston rod, this or these bridges being capable of breaking beyond a threshold of antagonistic forces exerted on said support grip part and said head, threshold being greater than the force necessary for the displacement of the piston but less than the opposing forces that a user is capable of exerting manually on said support grip part and said head.

The ring thus forms a means for moving the body and the case relative to each other between said positions of use and safety. The action enabling the body and the case to be brought into the safety position is carried out by the same manual grip as the grip by which the syringe is held during its use, and can therefore be carried out as a continuation of this use. .

The rupture of the breakable bridge (s) generates a sudden relative movement of the syringe body and of the protective case, such that this syringe body and this case are brought into the safety position at the end of this sudden movement. This movement limits or even prohibits any untimely control of the relative movement of the body and the case.

Advantageously, the protective case has wedging means making it possible to wedge laterally a syringe body placed in this case, these wedging means being radially movable so as to be able to wedge syringe bodies of different external diameters.

These wedging means can in particular be arranged on the distal side of the protective case, for laterally wedging the distal part of a syringe body. According to a preferred embodiment of these wedging means, the protective case has at least two diametrically opposite "U" shaped slots, which each individualize a radially movable tab, the internal face of each of these tabs having, side of the end of the tab not connected to the protective case, a boss projecting inside this case.

The syringe body bears against these bosses when it is placed in the protective case. In the case of syringe bodies with larger outside diameters which can be used with the syringe according to the invention, the tabs deform radially outwards so as to allow adequate erasure of said bosses. Advantageously, the connecting body that each retaining part comprises is made of a material having a degree of elastic flexibility, so that this connecting body has flexibility in the radial direction of the ring, this flexibility being such that it allows the arms of the holding part to be placed in several distinct radial positions.

This flexibility thus contributes to widening the range of syringe body diameters that can be received by the ring, and to ensuring perfect maintenance and perfect centering of a syringe body of a determined diameter.

Advantageously, each connecting body has a bent shape, that is to say comprises an intermediate part, connected to said arms and arranged substantially perpendicular to the axis of the ring, and a base part, connected to the ring and arranged substantially parallel to the axis of this ring.

Advantageously, the ring comprises two support grip parts as mentioned above, diametrically opposite;

- The connecting body of one of the holding parts is connected to the ring near one of these support grip projections and the connecting body of the other holding part is connected to the ring at close to each other of these projections, and

- At least part of these connecting bodies is shaped so as to project beyond the wall of the protective case.

The presence of these connecting bodies thus allows the fingers of the user to be moved away from the wall of the protective case, in order to prevent these fingers from rubbing against the protective case during the abovementioned abrupt movement. , and so they come to thwart this movement.

Advantageously:

- The syringe body has a proximal collar for its assembly with the ring; and the ring comprises assembly means to allow its assembly to this flange; these assembly means consist of two assembly parts of curved shape, arranged so as to substantially form a ring; these assembly parts are connected to the ring at peripheral zones and are made of a material having a degree of elastic flexibility; the peripheral areas of these assembly parts are located relative to each other at a distance greater than the external diameter of said collar while the median zones of these assembly parts are located relative to each other, in the undeformed state of these assembly parts, at a distance less than the external diameter of the collar; these median zones have, on the side of the ring by which the syringe body is engaged through the assembly parts, chamfers shaped to allow the radial erasure of these median zones at the time of this engagement.

The engagement of the flange between these assembly parts causes the elastic deformation of these at the level of said median zones, the chamfers of which allow radial erasure. Once the flange engaged beyond these assembly parts, the elastic return of the material constituting these assembly parts locks the syringe body.

Preferably, the ring comprises two retaining parts as mentioned above, arranged at a distal level with respect to said assembly parts; and

- At least one of said retaining parts has a flexible structure, in particular at the level of its connecting body, and is arranged so that the distance separating its arms, on the one hand, and said assembly parts, on the other part, ie less than the thickness of the collar.

This or these retaining parts are thus deformed when the flange is engaged between them and said assembly parts, and make it possible to maintain this flange pressed against these assembly parts. Perfect axial immobilization of the syringe body is thus obtained.

For a good understanding, the invention is again described below with reference to the appended diagrammatic drawing representing, by way of nonlimiting example, a preferred embodiment of the syringe which it relates. Figure 1 is a perspective view, in the form of a syringe, before injection of the product contained in this syringe; Figure 2 is a side view, in longitudinal section; Figure 3 is an enlarged view of a portion of the plunger rod that includes the syringe; Figure 4 is a detail view of a protective case that includes the syringe, on an enlarged scale and in longitudinal section; FIG. 5 is a side view, on an enlarged scale, of this case and of an actuating ring which the syringe comprises; Figure 6 is an axial view of this case and this ring, on the proximal side of the syringe; Figure 7 is a perspective view of the same ring; FIG. 8 is an axial view of this ring, and of a syringe body assembled to it, on the distal side of the syringe; Figure 9 is a view similar to Figure 8, after placement in the ring of a syringe body of larger diameter than the syringe body shown in Figure 8; FIG. 10 is a view of the syringe similar to FIG. 2, once the injection has been carried out; and FIG. 11 is a sectional view, on an enlarged scale, of the proximal part of the syringe, once the injection has been carried out. FIGS. 1 and 2 represent a syringe 1 with enhanced safety, comprising a syringe body 2, a piston 3, a piston rod 4, a protective case 5 and a ring 6 for actuating the case 5.

The syringe body 2 is of the conventional type, produced in particular from glass. It comprises a distal tip 10 comprising the injection needle 11 and a proximal collar 12, projecting radially outwards, which allows the assembly of the body 2 with the ring 6, as will be described below. The needle 11 can be mounted otherwise than by means of such a tip 10.

The piston 3 is of the conventional type. The piston rod 4 comprises two telescopic parts 15, 16, of which the distal 15 has a cross-shaped cross section and whose proximal 16 has a tubular shape, suitable for receiving the sliding part 15. Part 15 may have a cross-section of a shape other than a cross, or part 15 may have a tubular shape and part 16 may have a cross section in the shape of a cross.

Part 16 includes a support head 17 for the user's thumb.

As shown more particularly in FIG. 3, each of the four wings presented by part 15 is connected to part 16 by at least one bridge of material 20, so that these parts 15 and 16 are normally maintained in an extended position. , shown in Figures 1 and 2. These bridges 20 are strong enough to resist the force that it is necessary to exert on the rod 4 to make the piston 3 slide in the body 2, but are capable of breaking beyond a threshold of opposing forces. likely to be exerted on the ring 6 by the index and middle fingers of the user, on the one hand, and on the head 17 by the thumb of the user, on the other hand, according to the classic gesture of actuation of a syringe. Once these bridges 20 have broken, the part 15 can slide in the part 16 to the position shown in FIG. 10.

The part 15 is extended, on the proximal side, beyond the bridges 20, and this extension 21 has an outside diameter slightly smaller than the inside diameter of the part 16. This extension 21 makes it possible to stiffen the rod 4 longitudinally in order to avoid that this rod has, before rupture of the bridges 20, a zone of weakness in the transverse direction.

The head 17 has a circular shape and comprises a peripheral step 23, which delimits a cylindrical portion 17a of the head 17 and a flange 24 projecting radially outwards. As shown in FIG. 11, the diameter of this cylindrical portion 17a is such that this cylindrical portion 17a can be engaged with adjustment in the proximal portion 26 of the case 5 at the end of injection. The case 5 has a distal portion 25 of internal diameter greater than the external diameter of the body 2 and a proximal portion 26 receiving the sliding ring 6. The whole of this case 5 is made in one piece by molding a synthetic material having a degree of elastic flexibility such as a common plastic material. As shown in Figures 1 and 4, the portion 25 has two diametrically opposite "U" shaped slots, which each individualize a tab 30, this tab 30 being radially movable by elastic deformation at its base. The internal face of each of these tabs has, on the side of the end of the tab 30 not connected to the case 5, a boss 31 protruding inside this case.

The portion 26 of the case has two diametrically opposite longitudinal flats 26a (cf. FIG. 6), at the level of which two grooves 32 are arranged opening into the proximal end of the case 5. These grooves 32 are intended to receive sliding parts 56 of the ring 6, described below. This portion 26 further has two latching teeth 33 at its end edge, capable of ensuring the retention of the ring 6 on the case 5, as will also be described later.

Referring to Figure 7, it appears that the ring 6 comprises two slots 35 of arcuate shape, arranged symmetrically with respect to the axis of this ring. As can be seen in FIG. 6, these slots 35 are intended to receive the parts of the case 5 extending between said grooves 32.

Set back from the longitudinal ends of these slots 35, wedging shoulders 40 are formed, making it possible to lock the ring 6 in rotation relative to the case 5. Each slot 35 extends beyond each shoulder 40, in the form of '' a slot 41.

The ring 6 has two diametrically opposite support fins 45, projecting radially outwards, a proximal skirt 46, two holding parts 47 and two assembly parts 48. The assembly of this ring 6 is produced in a part by molding of a synthetic material having a degree of elastic flexibility such as a common plastic material.

The fins 45 are dimensioned to form bearing surfaces for the index and middle fingers of the user (shown diagrammatically by circles in broken lines in FIG. 5), and are connected to each other by portions intermediaries 50 of the ring 6.

The skirt 46 defines a housing suitable for receiving closely, at the end of injection, the head 17, as shown in FIGS. 10 and 11. It has two diametrically opposite windows 51 and a proximal chamfer 52, visible in particular in FIG. 11.

As shown in Figures 10 and 11, the ring 6 is intended to be engaged on the proximal end of the case 5 to beyond the teeth 33, which locks it definitively on the portion 26 of the case 5. The chamfer 52 is for its part intended to allow the engagement of the head 17 in the housing defined by the wall 46, until snap-fastening, at the end of use, of the rim 24 behind ribs 53 arranged in the areas of the ring 6 which delimit the proximal edges of the windows 51. This snap-in ensures the locking of the rod 4 in the position shown in FIGS. 10 and 11. The portion 17a of the head 17 ensures the retention of the teeth 33 in a radial position outer, which ensures the locking of the ring 6. The holding parts 47 are diametrically opposite and each have a fork shape, that is to say each comprise a pair of arms 55 and a connecting body 56 connecting these arms 55 to the ring 6.

The arms 55 are shaped, in particular rounded in the example shown, so as to be able to partially surround the syringe body 2, and comprise chamfers 57 arranged on their proximal side, by which a syringe body 2 is intended to be introduced into the across the ring 6.

Each arm 55 also comprises, at its free end, a boss 58 projecting radially inwards. It can include several such bosses.

The connecting body 56 of each retaining part 47 has an angled shape, that is to say comprises a base part, connected to the rest of the ring 6 and arranged substantially parallel to the axis of this ring 6, and an intermediate part, connected to said arms 55 and disposed substantially perpendicular to the axis of the ring 6.

The base parts are arranged on the same diameter as that according to which the fins 45 project.

As shown in Figure 5, the connecting bodies 56 are shaped so that after assembly of the ring 6 on the case 5, said intermediate parts are slidably engaged in the grooves 32 and that said base parts are projection relative to the wall of the case 5, thanks to the flats 26a of the portion 26.

As can be understood with reference to FIGS. 8 and 9, the arms 55 are intended to receive between them and to grip the syringe body 2, and can be elastically deformed so as to be able to receive between them, and grip, syringe bodies 2 of different outside diameters, in particular a body 2 known as "0.5 ml" as shown in FIG. 8 and a body 2 known as "1 ml" as shown in FIG. 9.

The chamfers 57 make it easier to engage a syringe body 2 between these arms, and the bosses 58 make it possible to immobilize and center a syringe body 2 of reduced diameter.

The relative flexibility of the connecting bodies 56 in the radial direction of the ring 6 makes it possible to place the arms 55 according to several distinct radial positions, and therefore to ensure good tightening of a syringe body 2, over a wide range of diameters of these. The tabs 30 and the bosses 31 make it possible, as can be deduced from FIG. 4, to wedge laterally syringe bodies 2 of different external diameters, the tabs 30 deforming outwardly if necessary so as to allow adequate erasure of the bosses 31. In addition, the presence of said base parts of the connecting bodies

56 allows the fingers of the user to be moved away from the wall of the case 5, as shown in FIG. 5, thus eliminating any risk of friction liable to slow the movement of activation of the locking system, or even compromise this lock. The two assembly parts 48 are delimited by the central opening of the ring 6 on the one hand and by the slots 35 on the other hand. They have a thickness such that they are elastically deformable in the radial direction, this deformability being made significant by virtue of the slots 41.

These parts 48 constitute for example an oval ring, connected, at their peripheral zones, the most distant from each other, to the ring 6, near the base parts of the connecting bodies 56. These peripheral zones are located relative to each other at a distance greater than the external diameter of the flange 12 of the body 2 while the median zones of this ring, the closest to each other, are located l relative to each other, in the undeformed state of the ring, at a distance less than the outside diameter of this flange 12.

FIG. 11 shows that the proximal part 26 of the case 5 has a diameter such that there is a space between the wall of this proximal part 26 and said median zones of said ring, this space allowing the radial deformation of these median zones.

In addition, chamfers 60 are arranged in these same median zones.

As can be deduced from FIGS. 6, 8, 9 and 11, the collar 12 is intended to be engaged through the aforementioned oval ring beyond the parts 48. The chamfers 60 of these parts 48 allow the erasing of said median zones to allow the passage of the flange 12. The elastic return of these parts 48 to their original shape allows the flange 12 to be locked beyond these parts 48.

Another embodiment may consist in that the assembly parts 48 constitute a substantially circular ring with one or more bosses in the middle zones, the most deformable. The body 2 is then perfectly assembled to the ring 6, without any radial play and with a very limited axial play.

In practice, as is understood by comparison of FIGS. 2 and 10, the user performs the injection by exerting opposing pressures on the fins 45 and on the head 17, by means of his middle finger and his index finger, respectively. on the one hand, and his thumb, on the other hand, according to the aforementioned classic gesture.

At the end of the injection, the piston 3 abuts against the bottom of the syringe body 2 or the head 17 abuts against the case 5; said opposing forces can then be exerted more intensively, until the bridges 20 break. This results in an abrupt relative displacement of the ring 6, and therefore of the syringe body 2, relative to the head 17, up to coming from the ring 6 and from the head 17 in a safety position, shown in FIG. 10, in which the needle 11 is fully retracted in the case 5. This sudden movement is carried out as an extension of the gesture of use syringe 1 for injection. The abrupt nature of this movement, associated with the separation of the user's fingers from the case 5 resulting from the presence of said base parts of the connecting bodies 56, ensures that the safety position is effectively reached in all cases.

The head 17 is locked automatically at the end of this sudden movement, by engagement of the rim 24 behind the ribs 53. The engagement of the portion 17a of the head 17 in the proximal end of the case 5, like the shows figure 11, eliminates, or at least makes very difficult, any attempt to unlock the rod 4.

As it appears from the above, the invention provides a syringe having the essential advantage of being able to receive syringe bodies of different diameters, so that this syringe can comprise standardized parts and to receive different syringe bodies, according to needs.

It goes without saying that the invention is not limited to the embodiment described above by way of example, but on the contrary embraces all the variant embodiments covered by the claims appended hereto. Thus, the invention relates to a device for medical use, with security, comprising (a) a syringe-type subassembly, comprising a body elongated along a reference axis; a needle disposed axially, communicating with the interior of said body, at the distal end of the latter; a piston movable inside said body to a distal position in abutment; and a piston rod emerging at the proximal end of said body, with a proximal grip portion;

(b) a safety sub-assembly, comprising a protective case mounted around the body, axially movable relative to the latter between two positions, namely an exposure position in which the needle is exposed and a safety position wherein the needle is entirely contained inside said protective case; according to the invention, in combination:

(i) the protective case is extended by a proximal portion beyond the proximal end of the body in the exposure position of said protective case, the piston rod emerging from the proximal end of said proximal portion;

(ii) an actuating ring extends radially from the proximal end of the body, being integral with the latter, and comprises an external part of support bearing, on either side of the body; (iii) axial sliding means between the actuating ring and the proximal portion of the protective case, said proximal portion being freely mounted in translation through the ring;

(iv) means for axially retracting the piston rod on itself, by axial thrust on the proximal part of the support grip when the piston is in its distal position in abutment, so that said proximal grip part 'support abuts against the proximal end of the protective case, then moves the latter to its safety position, still by pushing.

Claims

1 - Syringe, or similar device, comprising a syringe body (2) and a ring (6) to which the syringe body (2) is connected on the proximal side; syringe (1) characterized in that:

- the ring (6) comprises two holding parts (47) intended to receive and hold the syringe body (2) between them; each holding part (47) has a fork shape, that is to say comprises a pair of arms (55) and a connecting body (56) connecting these arms (55) to the ring (6), the arm (55) of each holding part (47) being shaped so as to be able to partially surround the syringe body (2); And

- said arms (55) are made of a material having a degree of elastic flexibility such that they can be elastically deformed so as to be able to receive between them, and grip, syringe bodies (2) of different external diameters.

2 - Syringe according to claim 1, characterized in that the holding parts (47) are diametrically opposed.

3 - Syringe according to claim 1 or claim 2, characterized in that each of the arms (55) of a holding part (47) comprises at least one boss (58) projecting radially inwards.

4 - Syringe according to one of claims 1 to 3, characterized in that a chamfer (57) is arranged in said arms (55) on the side of the ring (6) by which a syringe body (2) is intended to be introduced through this ring (6).

5 - Syringe according to one of claims 1 to 4, characterized in that it comprises a protective case (5), engaged around the syringe body (2), this case (5) and this body (2) being movable relative to each other between a position of use of the syringe (1), in which the needle (11) of the syringe is exposed, and a safety position, in which this needle (11) is surrounded by the case (5) so as to prevent any risk of pricks or cuts, and therefore possible contamination, of the user, after use; the protective case (5) comprises at least one longitudinal slot or groove (32); - the ring (6) forms a means for moving said body (2) and said case (5) relative to each other between said positions of use and security, and has for this purpose a part housed inside the protective case (5), comprising said holding parts (47), and at least one support part (45), engaged through of said light or groove (32) and projecting beyond the protective case (5), which serves to support the index or middle finger of the user's hand;

- the piston rod (4) of the syringe (1) comprises two telescopic parts (15, 16), one of which, distal, is connected to the piston (3) of the syringe, and the other, proximal, has a head (17) forming a support portion for the user's thumb; and - at least one breakable bridge (20) connects the two telescopic parts

(15, 16) of the piston rod (4), this or these bridges (20) being capable of breaking beyond a threshold of antagonistic forces exerted on said support portion (45) and said head (17), this threshold being greater than the force necessary for the movement of the piston (3) but less than the antagonistic forces that a user is likely to exert manually on said support portion (45) and said head ( 17).

6 - Syringe according to claim 5, characterized in that the protective case (5) has wedging means (30, 31) making it possible to wedge laterally a syringe body (2) placed in this case (5) , these wedging means (30, 31) being mobile radially so as to be able to wedging syringe bodies (2) of different external diameters.

7 - Syringe according to claim 6, characterized in that the wedging means (30, 31) are arranged on the distal side of the protective case

(5). 8 - Syringe according to claim 6 or claim 7, characterized in that the protective case (5) has at least two diametrically opposed "U"-shaped slots, which each individualize a radially movable tab (30), the internal face of each of these tabs (30) having, on the side of the end of the tab (30) not connected to the protective case (5), a boss (31) projecting inside this case (5).

9 - Syringe according to one of claims 1 to 8, characterized in that the connecting body (56) that each holding part (47) comprises is made of a material having a degree of elastic flexibility, such that this connecting body (56) has flexibility in the radial direction of the ring (6), this flexibility being such that it allows the arms (55) of the holding part (47) to be placed in several distinct radial positions. 10 - Syringe according to one of claims 1 to 9, characterized in that each connecting body (56) has a bent shape, that is to say comprises an intermediate part, connected to said arms (55) and arranged substantially perpendicular to the axis of the ring (6), and a base part, connected to the ring (6) and arranged substantially parallel to the axis of this ring (6).

11 - Syringe according to one of claims 5 to 10, characterized in that:

- the ring (6) comprises two diametrically opposed bearing projections (45);

- the connecting body (56) of one of the holding parts (47) is connected to the ring (6) near one of these support projections (45) and the connecting body ( 56) of the other holding part (47) is connected to the ring (6) near the other of these projections (45), and - at least part of these connecting bodies (56) is shaped like so as to protrude beyond the wall of the protective case (5).

12 - Syringe according to one of claims 1 to 11, characterized in that:

- the syringe body (2) has a proximal flange (12) for its assembly to the ring (6); And

- the ring (6) comprises assembly means (48) to allow its assembly to this collar; these assembly means are constituted by two assembly parts (48) of curved shape, arranged so as to substantially form a ring; these assembly parts (48) are connected to the ring (6) at peripheral zones and are made of a material having a degree of elastic flexibility; the peripheral zones of these assembly parts (48) are located relative to each other at a distance greater than the external diameter of said flange (12) while the middle zones of these assembly parts (48) are located relative to each other, in the undeformed state of these assembly parts (48), at a distance less than the external diameter of the flange (12); these middle zones have, on the side of the ring (6) by which the syringe body (2) is engaged through the assembly parts (48), chamfers shaped to allow the radial erasure of these middle zones at the moment of this commitment.

13 - Syringe according to claim 12, characterized in that: - the ring (6) comprises two assembly parts (48), arranged at a proximal level relative to said holding parts (47); And

- at least one of said holding parts (47) has a flexible structure, in particular at the level of its connecting body (56), and is arranged such that the distance separating its arms (55), on the one hand, and said assembly parts (48), on the other hand, are less than the thickness of the flange (12).

14 - Syringe according to one of claims 1 to 13, comprising (a) a subassembly (1) of the syringe type, comprising a body

(2) elongated along a reference axis; a needle (11) arranged axially, communicating with the interior of said body, at the distal end of the latter; a piston (4) movable inside said body to a distal abutment position; and a piston rod (4) emerging at the proximal end of said body (2), with a proximal bearing portion (17);

(b) a safety sub-assembly, comprising a protective case (5) mounted around the body (2), movable axially relative to the latter between two positions, namely an exposure position (see Figure 2) in which the needle (11) is exposed and a safety position (see Figure 10) in which the needle (11) is entirely contained inside said protective case (11); syringe characterized in that, in combination:

(i) the protective case (5) is extended by a proximal portion (26) beyond the proximal end of the body (2) in the exposure position of said protective case, the rod (4) of piston emerging from the proximal end of said proximal portion (26);

(ii) an actuating ring (6) extends radially from the proximal end of the body (2), being integral with the latter, and comprises an external part (45) for support, of on either side of the body (2);

(iii) means (41) for axial sliding between the actuating ring (6) and the proximal portion (26) of the protective case (5), said proximal portion being mounted freely in translation through the ring

(6); (iv) means (20) for axial retraction of the piston rod (4) on itself, by axial thrust on the proximal support portion (17) when the piston (3) is in its distal abutment position, so that said proximal support portion (17) abuts against the proximal end of the protective case (5), then moves the latter towards its safety position, always by pushing.