Abstract:
The invention concerns an injection syringe ( 10 ) comprising a syringe body ( 12 ) bearing an injecting needle ( 22 ) and an actuating piston ( 14 ) movably mounted in the body ( 12 ). The injecting needle ( 22 ) extends axially inside the body ( 12 ) up to a rear end ( 22 B) on one side of which is initially arranged in the body ( 12 ) a transverse wall ( 90, 96 ) capable of being perforated. Said transverse wall ( 90, 96 ) is movable relative to the needle from an initial position in which the transverse wall ( 90, 96 ) is at some distance from the needle ( 22 ) to a final position in which the transverse wall ( 90, 96 ) is pierced by said needle ( 22 ). The syringe comprises rigid means ( 64 ) for axially guiding the rear end ( 22 ) of the needle when the transverse wall ( 90, 96 ) is being pierced.

Description:
BACKGROUND OF THE INVENTION 
     The present invention concerns an injection syringe of the type which includes, on the one hand, an elongate syringe body comprising a tube and a front wall equipped with an injection needle, and, on the other hand, a rear actuating plunger which is mounted so as to be displaceable in the tube, and in which the injection needle continues axially inside the syringe body as far as a rear end, away from which is initially arranged, in the syringe body, at least one perforable transverse wall, the needle and the transverse wall being displaceable relative to one another from an initial position in which the transverse wall is away from the needle as far as a final position in which the transverse wall is pierced by the said needle. 
     The perforable transverse wall is, for example, carried by the actuating plunger. 
     In a variant, the transverse wall is for example formed by an intermediate plunger arranged in the syringe body between the rear end of the needle and the actuating plunger. The intermediate plunger then delimits, with the actuating plunger, a housing in which the fluid to be injected is contained. 
     In the latter case, when the actuating plunger is driven in, the intermediate plunger is perforated by the rear end of the needle in order to allow the fluid to flow through the needle. 
     If the section of the needle projecting inside the syringe body is long, the intermediate plunger risks being perforated with a slight angular and/or axial offset relative to the axis of the syringe body, because of the low rigidity of the needle. 
     Under these conditions, at the end of injection, when the actuating plunger comes into contact with the intermediate plunger and pushes it forwards with the view to moving it along the internal section of the needle, the offset existing between the axis of the needle and the axis of the syringe makes it difficult to move the intermediate plunger along the latter and risks leading to obstruction. 
     SUMMARY OF THE INVENTION 
     Similar problems are encountered when the transverse wall is carried by the front end of the actuating plunger and constitutes the front face of the latter. 
     The object of the invention is to make available a solution to the malfunctions of the syringe resulting from an angularly and/or axially offset perforation of the transverse wall by the rear end of the needle. 
     To this end, the subject of the invention is an injection syringe of the aforementioned type, characterized in that it includes rigid means for axial guiding of the rear end of the needle during the perforation of the transverse wall. 
     The rigid means for axial guiding of the rear end of the needle hold in position the part of the needle projecting inside the syringe body, so that the latter perforates the transverse wall along the common axis of the needle of the syringe, avoiding the obstruction problems mentioned above. 
     The subject of the invention is furthermore a needle holder assembly including a wall integral with an injection needle passing through the said wall, as well as a mobile protector of the injection end of the needle, displaceable relative to the needle between a retracted position behind the injection end of the needle and an active protection position in which the front end of the protector is in front of the injection end of the needle, which protector has legs which pass through the said body and extend along the said needle, characterized in that it includes a rigid member for axially guiding the rear end of the needle, which rigid axial guiding member is carried by the free ends of the legs of the protector. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood from reading the following description which is given solely by way of example and in which reference is made to the drawings, in which: 
     FIG. 1 is a longitudinal cross section through a syringe according to the invention, before use; 
     FIG. 2 is a detail, on a larger scale, of the zone surrounding the rear end of the needle of the syringe in FIG. 1; 
     FIGS. 3 to  6  are longitudinal cross sections through the syringe in FIG. 1, at different successive stages of use of the syringe, 
     FIG. 7 is a detail, on a larger scale, of the zone surrounding the front wall of the syringe after completion of the injection. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The injection syringe  10  represented in FIG. 1, with general form of revolution about axis X—X, is a disposable syringe. It is offered ready for use and already containing a medical fluid to be injected. It essentially includes an elongate syringe body  12  and a rear actuating plunger  14  which is mounted so as to be displaceable inside the body  12 . 
     The syringe body  12  is formed by a tube  16  at the front end of which there is fixed a needle holder  18  which bears a front wall  20  of the syringe body. This front wall  20  is equipped with an injection needle  22  passing through it. The latter includes a front injection end  22 A projecting from the body. The needle continues axially inside the body  12  as far as a rear or proximal end  22 B. The portion of the needle extending inside the syringe body is longer than the section of the needle projecting outside the syringe body. 
     The tube  16  is made of glass, for example, and has a circular cross section. Its front end is equipped externally with a peripheral flange  24  for holding the needle holder  18 . Likewise, at its rear end, the tube  16  includes externally a peripheral flange  24 A. Attached to this rear end there is a grip member  25  which facilitates gripping of the syringe body between the index finger and the middle finger. This grip member  25  includes a sleeve  26  snapped externally onto the end of the tube  16  on the flange  24 A, and two diametrically opposite tabs  27  for supporting the fingers. 
     The needle holder  18  is delimited externally by a sleeve  28 . The front wall  20  is made in one piece with the sleeve  28  and extends transversely at an intermediate point of the latter. Formed on the inner wall of the sleeve  28 , slightly behind the front wall  20 , there is a peripheral groove  30  for receiving the flange  24 . 
     The front wall  20  has an axial stud  32 , integral therewith, for fixing the injection needle  22 . This stud is directed towards the injection end  22 A of the needle and is received inside the space delimited by the sleeve  28 . 
     Three identical openings  34  are made through the front wall  20 . They are distributed at uniform angles around the stud  28  on one and the same circular contour and have an arc shape. The figures are longitudinal cross sections of the syringe made on either side of the axis X—X in the middle part of two of the openings  34 . 
     These openings  34  provide for the passage and guiding of a needle protector  36 . The latter includes, at the front, a protection ring  38  made of rigid plastic, of which the internal and external diameters are adapted so that the ring  38  lodges in the annular space defined between the stud  32  and the sleeve  18 . This ring is continued by three identical legs  40  which are elastically deformable and are spaced angularly at 120°. These legs  40  have, in cross section, a slight curvature corresponding to that of the ring  38  and they have a length substantially equal to the length of that portion of the needle  22  received in the syringe body  12 . 
     Furthermore, each leg  40  includes, over its entire width, a first internal bulge  42  arranged slightly to the rear of the ring  38 , and a second external bulge  44  arranged at its free end. 
     In addition, as is represented in FIG. 2, the legs  40  include, in the vicinity of their free ends, an internal recess  46  with cylindrical base extending the entire width of each leg. On each leg, this recess  46  is delimited, at the front, by a shoulder  48  formed in the thickness of the leg and, at the rear, by a projection  50  formed in the area of the bulge  44 . Each projection  50  carries a cam surface  52  formed by a substantially circular curved surface connecting the rounded summit of the projection  50  to the base of the recess  46 . 
     Means  64  for axial guiding of the rear end  22 B of the needle are held between the free ends of the legs  40 . These means include a member  66  of revolution held between the legs  40 . This member is made of a rigid material, in particular a rigid plastic material. It includes on the outside, to the rear, a truncated lateral wall  68 . It is bordered externally, to the front, by a collar  70 . The cylindrical lateral surface of the collar  70  is hollowed out, at its centre viewed in the direction of the axis X—X, with a shallow peripheral groove  71 . The depth of the groove is in particular less than the height of the bulges  44 . Before use of the syringe (FIGS.  1  and  2 ), the collar  70  is received in the recess  46  and its lateral surface bears on the cylindrical base of the recess  46 . The bulges  44  of the legs are then pressed against the inner surface of the tube  16 . Thus, the member  66  is held centred along the axis X—X by cooperation with the wall of the body of the syringe. 
     The member  66  includes an axial passage  72  passing right through it. This passage includes, at the front, a cylindrical portion  74  which is continued by a portion  76  whose cross section decreases progressively towards the rear. This portion  76  is defined by a truncated surface whose cross section, at its narrowest end, is substantially equal to that of the needle  22 . 
     As is represented in FIG. 2, before the syringe is used, the rear end  22  of the needle extends inside the passage  72 , so that the end of the needle is completely covered by the member  66 . 
     The rear plunger  14  includes an elongate pusher  78  with a cruciform cross section and has at its rear end a plate  80  for supporting the operator&#39;s thumb. At its opposite end there is an axial seat  82  which is open to the front and is used for receiving the rear end  22 B of the needle upon completion of injection. This seat  82 , of elongate shape along the axis X—X, has a circular cross section. It is delimited by a cylindrical wall  84  equipped with a calibrated vent  86 . 
     The wall  84  has on the outside, at its front end, a helical flange  88  for engaging and fixing a cup-shaped end membrane  90 . This membrane closes off the principal front opening of the seat  82  and constitutes a transverse wall adapted to slide in a leaktight manner inside the tube  16 . 
     As is represented in FIG. 1, the fluid to be injected  92  is arranged inside the tube  16  in a space delimited by the membrane  90  of the rear plunger and an intermediate plunger  94 . The intermediate plunger  94  includes a perforatable transverse wall  96  surrounded by a lateral sleeve  98  integral therewith and equipped with external peripheral ribs in order to ensure leaktightness of the liquid and the gas between this and the internal lateral wall of the tube  16 . The intermediate plunger  94  is initially applied against the end of the needle protector. The wall  96  and the sleeve  98  delimit, to the front, a cup  100  in which is partially received the rear end of the member  66 , which projects from the legs  40 . 
     The front end of the tube  16  is fitted in the sleeve  28  and is held there by snap-locking. The peripheral groove  30  being provided slightly to the rear in relation to the transverse wall  20 , the latter delimits, with the front end of the tube  16 , an annular channel  102  which is arranged immediately to the rear of the wall  20  and whose base is formed by the sleeve  28 . The width of the channel  102 , measured along the axis X—X, is substantially equal to twice the width of the bulges  44  measured along this same axis. At the front, the channel  102  is delimited by a shoulder  103  formed in the thickness of the sleeve  18 . The depth of the hollow space formed by the channel  102  is substantially equal to the height of the projections formed by the bulges  44 . 
     Moreover, a protective cap  104  for the needle  22  is fitted inside the sleeve  28  and covers the injection end  22 A of the needle. 
     The syringe is assembled in the following way. 
     The needle holder  18  is stuck on the needle  22 . The protector  36  is mounted through the front wall by engagement of the legs  40  in the passages  34 . It is arranged in such a way that the front protection ring  38  surrounds the stud  32  and the legs  40  extend along the rear part of the needle  22 . The member  66  is then put into place in the recess  46  by elastic deformation of the end of the legs  40 . The member  66  is held in position by the elasticity of the legs  40  whose free ends tend, as a result of their design, to approach the end  22 B of the needle. The front cap  104  is then put into place by being engaged in the sleeve  28 . 
     The needle holder  18 , thus equipped with the cap  104  and the member  66 , can be manipulated without risk of damage to the ends of the needle, the latter being protected at both ends. In particular, it can be distributed on assembly lines in vibratory bowl feeders. 
     In parallel with the assembling of the needle holder, the tube  16  is equipped with the grip member  25 . It is filled with the fluid  92  arranged between the intermediate plunger  94  and the actuating plunger  14 . The needle holder  18  is put into place by being snap-locked onto the front end of the tube  16 , as is represented in FIG.  1 . 
     The introduction of the legs  40  into the tube  16 , upon assembly of the needle holder on the tube, is easy because the legs  40  together with the member  66  form a single coherent element whose external diameter (diameter measured in the area of the bulges  44 ) corresponds exactly to the internal diameter of the tube  16 . 
     In order to proceed with the injection, the operator removes the cap  104 . In a customary manner, the operator then uses his thumb to exert pressure on the rear plunger  14  in the direction of the arrow F 1 , pressing on the tabs  27  with index finger and middle finger. 
     The pressure thus exerted, transmitted by way of the liquid  92  to the intermediate plunger  94 , provokes the displacement of the latter, along a travel marked C 1 , towards the proximal end  22 B of the needle. The latter perforates the wall  96  of the intermediate plunger during the movement of the latter. The displacement of the intermediate plunger  94  is accompanied by the forward displacement of the needle protector  36 . 
     During driving, the member  66  is driven forwards by the needle protector  36  in the recess  46  in which it is held. This is because the legs  40  are applied along the bulges  44  on the lateral wall of the tube  16 , thereby holding the member  66  in the recess  46 . 
     Moreover, during the movement of the member  66 , the wall  16  ensures, by way of the legs  40 , that it is centred and axially guided in order to guarantee its displacement strictly along the axis X—X. 
     During the joint movement of the intermediate plunger  94  and the member  66 , the rear end  22 B of the needle first comes into contact with the truncated surface  76 . The latter ensures, as the displacement of the member  66  proceeds, progressive centring of the end  22 B of the needle. It additionally provides axial guiding of the needle. Thus, when the rear end  22 B of the needle emerges from the member  66 , the portion of the needle arranged inside the body extends strictly along the axis X—X. It is held there by the end of reduced cross section of the passage  72 . The rear end  22 B of the needle thus perforates the wall  96  while still being held laterally by the member  66  arranged slightly in front on the needle. 
     In these conditions, the perforation of the intermediate plunger  94  takes place axially and in the central part thereof, thereby guaranteeing easy subsequent displacement of the plunger  94  on the whole inner portion of the needle  22 . 
     The displacement of the intermediate plunger  94  impaled on the needle  22  is stopped at the end of the travel C 1  when the bulges  42  come into abutment on the stud  32 , as is represented in FIG.  3 . For this purpose, the bulges  42  are dimensioned in such a way that the protector  36  is held in its retracted position in FIG. 3 in which the ring  38  extends in the sleeve  18  despite the pressure exerted by the intermediate plunger. 
     The travel C 1  corresponds to the purging of the syringe. In fact, the displacement of the rear plunger  14  while the intermediate plunger  94  is perforated by the needle ensures evacuation of the air contained in the needle and the flow of a small quantity of the fluid  92  through the latter. 
     After this purge, the injection end  22 A of the needle is introduced into the patient&#39;s tissue. 
     The fluid  92  is then injected through the needle  22  under the effect of the pressure on the rear plunger  14  which is driven in along a travel C 2  as far as the position represented in FIG.  4 . In this position, the bulk of the fluid  92  is injected and the membrane  90  comes into contact with the rear surface of the intermediate plunger  94 . 
     The continued pressure exerted by the operator on the rear plunger  14  then causes disengagement of the bulges  42  by means of elastic deformation of the legs  40 . This results in the forward displacement of the protector  36 . When the ring  38  comes into contact with the patient&#39;s skin, the travel of the protector is stopped, and continued approximation, along a travel C 3 , of the thumb pressing on the plate  80  and of the other fingers held against the tabs  27 , causes the syringe body  12  to reverse in the direction of the arrow F 2  (FIG.  5 ). 
     It will be appreciated that the reverse movement of the body  12  causes extraction of the injection needle  22  from the patient&#39;s body. 
     It is also possible, by simply pulling on the syringe body, to extract the needle from the patient&#39;s tissue while the syringe is in the position represented in FIG.  4 . The driving of the rear plunger  14  into the syringe body is in this case continued with the syringe disengaged from any contact with the patient. 
     Furthermore, the rear end  22 B of the needle pierces through the membrane  90  and is received in the seat  82 . On account of the presence of the member  66 , the perforation of the membrane  90  takes place strictly along the axis X—X. 
     In the position represented in FIG. 5, the bulges  44  carried externally by the free end of the legs  40  are arranged opposite the annular channel  102 . Moreover, in this position, the member  66  lies with its front face abutting on the stud  32  and the front face  20 . It is thus immobilized axially. 
     During the final phase of driving the plunger  14  along a travel C 4 , the needle protector  36  is displaced forwards under the action of the pressure of the rear plunger  14  transmitted by the intermediate plunger  94  which is still in contact with the free end of the legs  44 . For this purpose, the rear end of the member  66  which projects in relation to the legs  40  withdraws into the cup  100 , thus allowing the intermediate plunger  94  to slide despite the immobilization of the member  66 . 
     While the member  66  is immobilized, the cam surfaces  52  formed at the rear of the recess  46  cooperate with the collar  70  forming a cam follower in order to space the free ends of the legs apart. As a result of this spacing apart, the bulges  44  are received in the annular channel  102 , as is represented on a larger scale in FIG.  7 . 
     In this position, the projections  50  bordering the recess  46  at the rear rest on the lateral surface of the collar  70 , thereby ensuring positive retention of the bulges  44  inside the annular channel  102  and positive blocking of the needle protector  36 . 
     Moreover, the projections  50  are received in the peripheral groove  71  of the collar, thereby ensuring axial connection of the member  66  and of the needle protector  36 . Thus, even if the needle protector is caused to displace slightly axially (along the length of the annular channel  102 ), the member  66  is entrained and remains opposite the bulges  44 , which permits permanent positive retention of the bulges  44  in the channel  102 . Thus, the ends of the legs  40  cannot be released, which guarantees the locking of the needle protector  36  in its active protection position. 
     In FIGS. 6 and 7, the protector  36  is in the active protection position and extends around the injection end  22 A of the needle. The front face of the protection ring  38  is thus situated slightly in front of the end  22 A of the injection needle, prohibiting any contact between the latter and an external element and thereby preventing any risk of the operator being contaminated by a stick injury. 
     It will be appreciated that the bulges  44  engaged in the channel  102  between the shoulder  103  and the end of the tube  16  hold the protector  36  firmly in the protection position, thereby prohibiting any accidental retraction. This hold is in fact guaranteed by the presence of the member  66 , whose collar  70  keeps the ends of the legs  40  spaced apart. 
     The membrane  90  having been perforated by the rear end  22 B of the needle, the syringe is rendered unavailable for further use. The reason is that this perforation prohibits the suction effect normally obtained inside the body upon withdrawal of the rear plunger on account of the presence of the vent  86 . Likewise, the rear plunger, once perforated, does not allow expulsion, via the injection needle  22 , of any liquid re-introduced into the syringe body. 
     It will be appreciated that in a syringe such as the one described here, the member  66  guarantees a correct perforation of the intermediate plunger  94 . This is because the end  22 B of the needle, guided by the truncated surface  76 , penetrates at the centre of the plunger  96  and along the axis X—X of the syringe. 
     In the example described, the member  66  is initially arranged around the end  22 B. However, the member  66  can be arranged on the needle slightly in front of its rear end, while still correctly exercising its guide function for the rear end of the needle. 
     Moreover, in the case of a syringe in which the needle holder  18  is equipped with sealing means between the wall  20  and the legs  40 , the intermediate plunger  94  is omitted. However, the member  66  is advantageously kept in order to ensure, in the position analogous to that in FIG. 4, perforation of the transverse wall  90  of the rear plunger strictly along the axis X—X of the syringe, thus guaranteeing correct axial penetration of the needle in the seat  82 . 
     In a variant which is not shown, the projecting elements formed by the bulges  44  and the associated complementary recessed element formed by the annular channel  102  are inverted. Thus, the legs include recesses externally, whilst the syringe body has complementary projections with a view to holding the protector in its active protection position. 
     In this variant too, the member  66  ensures positive retention of the engagement of the associated projecting and recessed reliefs when the needle protector is in its active protection position.