FR2838970A1 - Safety syringe includes hub inserted in neck portion of barrel, plunger movably received in barrel behind the neck portion, and cap removably closing the hub and entire cannula - Google Patents

Abstract

A safety syringe includes a hub (3) inserted in a neck portion (12) of a barrel (1) with a shoulder portion air-tightly abutting on an internal stepped surface (13) of the neck portion that has a reducing diameter inner wall surface (121) corresponding to respective hub outer wall surface (361). A plunger (2) is movably received in the barrel behind the neck portion. A safety syringe comprises a barrel, a front end of which being diametrically reduced neck portion having a rim radially inward inclined to provide a beveled annular surface. A rear end of the beveled annular surface is radially inwardly projecting from an inner wall surface of the neck portion to provide a stepped surface. The inner wall surface of the neck portion defines a variable-diameter bore, diameters of which gradually reducing from top to bottom. A plunger is movably received in the barrel behind the neck portion. A hub holding a cannula at its front end is provided at a predetermined position with an annular shoulder portion (32), and at a predetermined position on a rear portion (36) a distance behind the annular shoulder portion with a receiving hole diametrically extended through the rear portion. The rear portion is extended between the annular shoulder portion and a rear end of the hub, and has a variable-diameter outer wall surface gradually tapered rearward. A cap removably closes the hub and entire cannula, and has a rear portion with reduced wall thickness, so that a stepped surface is formed on an inner wall surface of the cap at a predetermined position close to its rear end. The hub is inserted in the neck portion of the barrel in a manner that the annular shoulder portion is abutted on the stepped surface in the neck portion to prevent the hub from forward separating from the barrel and to form a first airtight joint (34) of the hub with the barrel. The rearward tapered variable-diameter outer wall surface of the rear portion of the hub is received in the rearward tapered inner wall surface of the neck portion in a relation of compression fit to form at a certain contacted position a second airtight joint (35) of the hub and the barrel.

Description

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SAFETY SYRINGE

  In ancient medicine, a syringe used was completely sterilized and then reused later. Any incomplete sterilization was extremely dangerous since it might lead to a new infection in the patient and / or another person. To avoid this type of subsequent infection, disposable disposable syringes have been developed. Although the disposable syringe avoids the problem of subsequent infections due to incomplete sterilization of conventional syringes, it does not include any means of protecting the used and discarded hollow needle which may unexpectedly prick the caregiver or managers of cleaning and producing another type of infection and injury. To solve this problem, various types of safety syringes are being developed. US Pat. Nos. 5,899,887, 6,033,385 and 5,569,203 all disclose a safety syringe, the cylinder and sleeve of which are assembled in a special manner which allows the sleeve and the hollow needle used in the cylinder to be retracted before disposing of the syringe after use. , to prevent the syringe from unexpectedly pricking other personnel, causing infection and damage

adverse.

  However, all the safety syringes of the prior art developed to improve conventional syringes have drawbacks with regard to the means of driving towards the rear of the sleeve and the used hollow needle. It is understood that a safety syringe must respond to basic imperative but nevertheless very important trots, namely: (a) the sleeve must be firmly assembled to the cylinder, (b) the sleeve of the syringe which has been used must be able to be t

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  drawn inside the cylinder and, most importantly, (c) the joint between the sleeve and the cylinder must be completely airtight. A problem frequently encountered by manufacturers when designing the safety syringe is that when the requirements for tight assembly between the sleeve and the cylinder and a completely airtight seal between the sleeve and the cylinder are specifically requirements, it can become difficult to easily pull the syringe sleeve back after use; and, on the other hand, when it is the imperative of a sleeve easily retractable towards the rear of the syringe after use which is required, the firm and airtight assembly between the sleeve and

  the cylinder is inevitably sacrificed.

  FIGS. 1A to 1C illustrate three different conventional safety syringes with a retractable sleeve towards the rear. These syringes further include a cylinder and a plunger with a protruding forward cone, provided at an end anterior to the plunger for coupling to the sleeve, so that the plunger can entrain the sleeve back into the cylinder of the syringe when it is coupled to the sleeve. During the practical use of these conventional safety syringes, when the plunger is pushed until it is near an anterior end of the cylinder and the protruding cap comes into contact with a rear end of the sleeve, an anterior head of the cBne projecting closes a passage through which a medical liquid is sent from the cylinder to the sleeve, thus closing a space between the piston and the front end of the cylinder. At this stage, part of the medical liquid which remains in this closed space can no longer be expelled into the sleeve and opposes resistance to any subsequent embedding of the cable in the sleeve. He b

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  it is therefore necessary to push harder to achieve this embedding, which inevitably causes vibrations in the syringe during the injection and, therefore, is painful for the patient. In the worst case, the c8ne does not fit into the sleeve at all. Figure 1C illustrates the safety syringe disclosed in US Patent No. 5,569,203, syringe in which the medical liquid residue! in the cylinder prevents linkage of the c8ne in the sleeve. Figures 1A and 1B illustrate the safety syringes disclosed in US Pat. Nos. 5,899,887 and 6,033,385, respectively, as improvements made to US Patent No. 5,569,303. As will be seen from Figures 1A and 1B, the syringes Safety devices illustrated include a sleeve having, on its rear peripheral wall, cone-receiving holes and, on its internal wall surface, tongues inclined radially inwards. However, a syringe having such a design is almost impossible to achieve according to a plastic injection molding process. Even if a syringe of this nature is molded correctly, it does not include any means, between the c8ne and the tabs, to prevent an inadvertent embedding of the c8ne in the sleeve. Therefore, it is perfectly possible that the piston is undesirably engaged in the sleeve when it is pushed forward to expel the air out of the cylinder in order to aspirate the medical liquid

in the cylinder for injection.

  The inventor has therefore developed an improved safety syringe in order to overcome the existing drawbacks.

  in conventional safety syringes.

  One of the main objectives of the present invention is to provide a safety syringe having a sleeve and a cylinder joined to one another in a connection

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  firm which prohibits the extraction towards the front of the sleeve with a view to its separation from an anterior end of the cylinder after said sleeve has been inserted towards the rear in the cylinder, and guarantees an airtight seal between the sleeve and cylinder. Another object of the invention is to provide a safety syringe having a closed end piece on a sleeve of the cylinder, a rear edge of the end piece making it possible to define an optimal position for assembling the sleeve and the cylinder of the syringe in relation firm and

airtight.

  Another objective of the present invention is to provide a safety syringe, a cylinder of which has an anterior part forming a neck, and a sleeve of which is conform and dimensioned to fit tightly in the neck forming part of the cylinder in order to guarantee a airtight contact of an outer wall surface of the sleeve with an inner wall surface of the colt portion Yet another object of the present invention is to provide a safety syringe, which has a plunger provided, front end, of a grooved cone and a sleeve of which is provided with a receiving hole for the cone of the piston for the purpose of embedding the cone in said hole, so that, when the piston is pushed forward and that the cone, at first, closes a posterior end of the sleeve, the medical liquid which remains in an anterior end of the cylinder between the piston and the sleeve, can still be ejected inside the sleeve by the inside rmaire of the groove provided on the cone, which allows to move the piston forward and backwards

  to embed the cone in the receptacle hole of the sleeve.

  Yet another objective of the present invention is to provide a safety syringe, a sleeve of which is

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  provided, at a point situated at a certain distance in front of its rear end, with a receiving hole, and a piston of which is provided, at its front end, with a cone intended to be embedded in the receiving hole on the sleeve, so that when the plunger is pushed forward to expel air from the syringe barrel before the medical liquid is drawn into the barrel, the cone first touches the end back of the sleeve, which alerts the operator to stop pushing the piston further. Any installation by mistake of the cone with the sleeve can thus

be avoided.

  The structure and the technical means adopted by the present invention to achieve the above as well as other objectives will be better understood if we refer to

  the following detailed description of embodiments

  preferential as well as to the annexed schemes, in which: FIG. 1A is an exploded perspective view of a first conventional safety syringe; Figure 1B is an assembled sectional view of a second conventional safety syringe; Figure 1C is an exploded perspective view of a third conventional safety syringe; Figure 2 is a partially exploded perspective view of a safety syringe according to the present invention; Figure 3 is a sectional view illustrating the sleeve with its tip and the cylinder of the safety syringe of the present invention before their assembly with each other; Figure 4 is a sectional view of a portion of safety syringe according to the invention, which illustrates the sleeve covered with a tip and the cylinder once they have been assembled with each other;

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  Figure 5 is a sectional view of a portion of safety syringe according to the present invention, the tip of which is separated from the sleeve and cylinder assembly for its removal; Figure 6 is a sectional view of a portion of safety syringe according to the invention in which the piston is pushed as far forward as possible to allow the embedding of its cone in the sleeve; and FIG. 7 is a sectional view of a portion of syringe according to the invention illustrating the sleeve provided with the worn hollow needle, drawn in displacement towards

  the rear in the cylinder by the piston.

  Figure 2 is a partially exploded perspective view of a safety syringe according to the present invention. As illustrated, the safety syringe mainly comprises a cylinder 1, a piston 2 which can move inside the cylinder 1, a sleeve 3 mounted on an anterior end of the cylinder 1, and a nozzle 4

closes on the sleeve 3.

  The front end of the cylinder 1 is reduced diametrically (see also Figure 3) to define a neck portion 12, one edge of which is inclined radially inwardly so as to produce a beveled annular surface 11. In addition, one end posterior of the beveled annular surface 11 projects radially inwards from an interior wall surface 121 of the neck portion 12 to define a bearing surface (shoulder) 13. It should be emphasized that the interior wall surface 121 of the part forming a neck 12 delimits a bore with variable diameter, the diameters of which gradually decrease from the front towards the rear (that is to say from the outside towards

inside the cylinder).

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  The piston 2 is a long element arranged in the cylinder 1 from the rear end of the cylinder 1. The piston 2 is provided, at its anterior end, with a piston tip 21 having an end surface from which a c6ne 22 projects forward. A groove 23 is formed along the cone 22

on either side of its summit.

  The sleeve 3 is designed to carry a hollow needle 31 on its anterior end. An annular part forming a shoulder 32 is formed at a predetermined point on the sleeve 3. A receiving hole 33 is provided on a rear part 36 of the sleeve 3 at a certain distance behind the annular part forming a shoulder 32 and at a certain distance at the front of a rear end of the sleeve 3 to extend diametrically through the sleeve 3. It should be emphasized that the rear part 36 of the sleeve 3, which extends between the part forming the annular shoulder 32 and the rear end, has an outer wall surface 361 of variable diameter. It should also be emphasized that the outer wall surface of variable diameter 361 of the sleeve 3 has a configuration which corresponds to that of the inner wall surface 121 of variable diameter of the neck portion 12 of the cylinder 1, and of dimensions slightly greater than those of the interior wall surface 121 of variable diameter. The end piece 4 is dimensioned so that it is possible to close the sleeve 3 in a con, removable manner to completely cover the hollow needle 31 which is inside. A posterior part of the end piece 4 has a reduced wall thickness, so as to define a bearing surface (shoulder) 41 on an interior wall surface of the end piece 4 at a predetermined point close to an end

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  rear of the end piece 4, and an inside diameter of the rear part of the end piece 4 is chosen so that said rear part fits tightly around an anterior part of the sleeve 3 located at the front of the annular shoulder 32. To assemble the safety syringe of the present invention, the end piece 4 is first of all placed on the sleeve 3 and the hollow needle 31, so that the bearing surface 41 of the end piece 4 comes into abutment against the front end of the sleeve 3. At this stage, the rear part of the end piece 4 is tightly arranged around the front part of the sleeve 3, the rear end of the end piece 4 extending at a certain distance above the part forming the annular shoulder 32, as illustrated in FIG. 3. Next, the sleeve 3, partially covered with the end piece 4, is assembled to the cylinder 1 by insertion of the rear part 36 of the sleeve 3 in the part forming neck 12 of cylinder 1 until the end the back of the end piece 4 abuts against the rim, that is to say an anterior end, of the neck portion 12, as illustrated in FIG. 4. At this stage, the rear portion 36 of the sleeve 3 is arranged in the neck portion 12, the annular shoulder portion 32 extending immediately behind the beveled annular surface 11 to abut against the bearing surface 13, thus allowing optimal assembly of the end piece 4 and the sleeve 3 with the cylinder 1, and the production of a first airtight seal 34 between the bearing surface 13 and the part forming the annular shoulder 32. The sleeve 3, with the part forming the annular shoulder 32 which abuts against the bearing surface 13, can no longer be moved forward and separates from the neck portion 12. Furthermore, since

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  the outer wall surface 361 of variable diameter of the rear part 36 of the sleeve 3 has a shape which corresponds to that of the inner wall surface 121 of variable diameter of the neck portion 12 of the cylinder 1 and of dimensions slightly larger than those of the latter, and given that the two surfaces 361 and 121 are designed conical with flaring towards the front within limits of optimal length and optimal angle, the rear part 36 of the sleeve 3 is in fact maintained in the part forming neck 12 of cylinder 1 in a sort of compression fit in a certain position between the interior wall surface 121 of the neck portion 12 and the exterior wall surface 361 of the rear portion 36 of the sleeve, forming a second

airtight seal 35.

  With the first and second airtight seals 34, 35, the safety syringe of the present invention fully meets one of the imperatives

  most important requirements of safety syringes.

  To use the safety syringe of the present invention, the tip 4 is pulled in a direction opposite to the cylinder 1, that is to say it is moved forward to expose the hollow needle 31 in view to carry out an injection, as illustrated in FIG. 5. Then, the piston 2 is pushed forward until the cone 22 on the piston tip 21 is engaged in the hole

  receptor 33 of the sleeve 3, as illustrated in FIG. 6.

  When the c8ne 22 comes into initial contact with the posterior end of the sleeve 3, and thus substantially closes the posterior end of the sleeve 3, as illustrated in FIG. 5, the groove 23 provided on the top of the c8ne 22 allows the medical liquid to restart in the cylinder 1, between the piston end 21 and the sleeve 3, to continue to flow into the sleeve 3 without generating

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  resistance to the piston 2. Thus, the piston 2 can still be gently pushed forward without causing vibrations during the injection or causing projections of the medical liquid out of the hollow needle 31. When the injection is finished, it just pull the piston 2 towards the rear and the sleeve 3, with the hollow needle 31 which has been used, wind moved towards the rear to leave the neck forming part 12 in the cylinder 1, as illustrated in

Figure 7.

  With the precise arrangement, the safety syringe of the present invention completely satisfies the most fundamental and important imperative trots, namely a firm connection of the sleeve on the cylinder, a sleeve and a hollow hollow needle retractable inside the cylinder, and absolute air tightness

  at the joint between the sleeve and the cylinder.

Claims (2)

RESELL I CAT I ONS:   1. A safety syringe comprising: a cylinder (1), an anterior end of which is a neck portion (12) of reduced diameter having an edge which is inclined radially inwards to define a beveled annular surface (11), a posterior end of said beveled annular surface projecting radially inward from an interior wall surface (121) of said neck portion to form a bearing surface (13), and said interior wall surface (121) of said part forming a neck delimiting a bore with variable diameter, the diameters of which gradually decrease from the front to the rear; To a piston (2) movable in said cylinder (1) at the rear of said neck portion (12); To a sleeve (3) carry a hollow needle (31) on an anterior end of the sleeve and being provided, at a predetermined point, with an annular shoulder portion (32), and, at a predetermined point with a posterior portion (36 ), at a certain distance behind said portion forming an annular shoulder (32), from a receiving hole (33) which extends diametrically through said rear portion; said posterior part extending between said annular shoulder part and an end posterior to said sleeve and having a surface 12 2838970   outer wall (361) of variable diameter flared gradually forward; To a nozzle (4) for removably covering said sleeve (3) and said whole hollow needle (31), having a rear part having a reduced wall thickness so as to form a bearing surface (41) on a surface inner wall at said end piece, at a predetermined point close to an end posterior to said end piece, and to said sleeve being arranged in said neck portion of said cylinder so that said annular shoulder portion (32) abuts said bearing surface (13) in said neck portion (12) to prevent dissociation of the sleeve and the cylinder by moving said sleeve forward and to form a first airtight seal (34) between said sleeve and said cylinder, and so that said outer diameter surface (361) of variable diameter flared towards the front of said rear portion (36) to said sleeve is held in said inner wall surface (121) flared towards the front of lad ite neck part (12) in an adjustment relationship by compression to form, at a certain point of contact, a second seal (35)   the air between said sleeve and said cylinder.   2. A safety syringe according to claim 1, in which said piston (2) is a long element disposed in said cylinder (1), said piston being provided, at its anterior end, with a piston tip (21), a an anterior end of which is provided a cone (22) making 13 2838970   protruding forward, and having a groove (23) which extends on either side of its top, intended to be