WO1993000949A1

WO1993000949A1 - Single-shot disposable syringe

Info

Publication number: WO1993000949A1
Application number: PCT/EP1992/001455
Authority: WO
Inventors: Paolo Romagnoli
Original assignee: Ivalda Spa; Pentaferte Srl
Priority date: 1991-07-02
Filing date: 1992-06-29
Publication date: 1993-01-21
Also published as: ITVI910107A1; IT1253104B; AU2193892A; ITVI910107A0

Abstract

The invention discloses a single-shot disposable syringe for pharmaceutical use which presents in combination: a cylindrical sleeve (8) external to the syringe cylinder (2), equipped with a flange (10) on which the fingers of the hand holding the syringe can rest; a spring (15) placed between the sleeve and the cylinder (2) of said syringe; at least one pair of elastic hooks (11) which are attached to the cylindrical sleeve and which hold the syringe cylinder as long as the plunger (3) of the syringe is not at the end of its stroke; and an intermediate flange (20) on the plunger rod. When the plunger (3) is pushed to the end of the cylinder (2), in order to expell all the liquid contained in the syringe, the intermediate flange (20) on the plunger rod interacts with the elastic hooks (11) disengaging the syringe cylinder from the sleeve. Then under the spring force the syringe cylinder moves relative to the sleeve, so that the needle becomes protected by the sleeve (8).

Description

SINGLE-SHOT DISPOSABLE SYRINGE The invention discloses a single-shot, disposable syringe for pharmaceutical use of the type with a needle which is protected after the injection has been given. As it is well known, the main purpose proposed by the manufacture of a single-shot, disposable syringe having its needle protected after the injection has been given, is that of preventing as much as possible all the contamina- tion and infection accidents which may arise from the voluntary or the accidental contact with a needle of an already used syringe. Particularly the spreading of highly contagious diseases, such as AIDS or viral hepatitis leads the health authori- ties to promote the use of single-shot, disposable syr- inges, yielding certain hygenical unrenounceable guaran- tees, such that they can prevent infection accidents after they have been used. The single-shot, disposable syringes having a needle which is protected after they have been used, are made essential- ly of a plastic syringe complete with a device protecting the needle which is activated after the injection has been given and which in fact prevents both the use of the same syringe for subsequent injections, and the contact, however accidental, of the already used needle. The Italian patent application 22810/A/88 describes a single-shot disposable syringe, wherein, after the injec- tion has been given and the plunger rod has been released, the needle goes back inside the syringe body because of the action of a spring and, should there be an attempt at re- using it, the tip of the needle is blocked against a small block contained within the protecting element, so that the needle itself no longer finds its way out of the exit opening. The mechanism constituting said invention is made of a large number of components and is, therefore, extremely costly and fairly complicated to manufacture. The purpose of the present invention is to overcome the mentioned inconveniences. The first purpose is that of obtaining a single-shot, disposable syringe preventing anybody from using it again after it has been used once, wherein the needle is protec- ted immediately after the injection has been given. In fact, the purpose proposed by the invention is that of preventing any accidental contamination for the medical operators both during the process of giving injections and during the process of collecting the used syringes and disposing of them. It also has the purpose of preventing accidents of infectious contamination among the population or the sanitations operators whose task it is to collect the used syringes. It is also proposed to prevent contagion among drug addicts issuing from the promiscuous use and from the renewed use of syringes. All the mentioned purposes and others, which will be better described hereinafter, are reached by a single-shot, dispo- sable syringe according to the invention which, in co - pliance with the first claim comprises; - a syringe consisting of a cylinder within which slides a plunger activated by a rod, wherein an injection needle is attached at the end of said syringe having a narrower section; - an injection needle attached to said cylinder; - a cap covering the needle; - a cylindrical sleeve suited to hold in its interior the cylinder of the syringe and to maintain said position through some elastic hooks; - a spring or equivalent elastic means positioned between the sleeve and the cylinder of said syringe, characterized in that it presents in combination: - an outer flange belonging to the sleeve and made so that the fingers of the hand engaging the syringe giving the injection can rest on it; - at least one pair of elastic hooks belonging to the sleeve and suited to hold back the lower rim of the syringe plunger when the syringe plunger has not reached the end of its stroke, the spring positioned between said sleeve and said cylinder being under stress; - an intermediate flange belonging to the plunger rod and positioned close to the rod-pushing flange, said interme- diate flange being suited to co-operate with the terminal parts of said hooks, in that it opens them up, thereby unhooking them and causing the cylinder of the syringe to draw back from the cylindrical sleeve; - blocking means preventing the further reciprocal sliding between the syringe cylinder and the sleeve, after the syringe has drawn back in relation to the sleeve, once the injecting operation has been completed. According to the invention, the single-shot, disposable syringe allows the syringe itself to draw back immediately in relation to the cylindrical sleeve, said sleeve remai- ning firmly in the hand of the operator giving the injec- tion. Thus, the result is that not only does the needle go back into the protected area of the cylindrical sleeve, but also that no shock is caused by the syringe or by its protection to the part of the body interested by the injec- tion. According to a preferred embodiment of the invention, the presence of an elastic washer which is restrained within an annular recess of the cylindrical sleeve when the syringe slides back, prevents the repetition of the forward sli- ding motion of the syringe cylinder and, therefore, of the needle which is attached to it, thereby preventing a rene- wed use of the syringe or, at any rate, preventing the needle from coming out of the protected area inside the sleeve. Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indica- ting preferred embodiments of the invention, are given by way of illustration only, since various changes and odifi- cations within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description and from the drawings, wherein; - Fig. 1 shows in a cross-section the syringe of the inven- tion before it is used; - Fig. 2 shows the syringe of the invention during the suction phase with the safety bushing free from the hooks which held it before; - Fig. 3 shows again the syringe during the injection, without the safety bushing; - Fig. 4 shows the syringe during the injecting operation while the plunger is reaching its position of maximum pressure; - Fig. 5 shows the withdrawal of the syringe in relation to the sleeve protecting the needle after the injection; - Fig. 6 shows an exploded view of the components of the single-shot, disposable syringe of the invention. With reference to the mentioned figures, it can be observed that the syringe according to the invention, indicated as a whole with 1, presents a cylinder 2, within which slides plunger 3, activated by rod 4. The end of cylinder 2 having a narrower and tapered section, as indicated in 5, or better said, the section of a truncated cone, is suited to receive a needle 6. The rod 4 of plunger 3 ends with a pushing flange 7, which is the flange on which pressure is exerted in order to give the injection. The components which have been described so far are nothing more than the components which usually make up a single- shot syringe: in fact the following components have been described: the cylinder, the plunger with the rod and the needle, all of them being the components which are used for the present invention, using those already on the market, with the exception of some minor modifications. The novelty of the syringe of the invention consists, in fact, of the presence of the cylindrical sleeve 8 and in the way said sleeve inter-acts with the rest of the syrin- ge. As can be observed in the different figures of drawing and especially in Fig. 5, the cylindrical sleeve 8 comprises a cylindrical part 9 ending with a lower flange 10, which is meant as a support for the fingers of the hand holding the syringe while giving the injection. The cylindrical sleeve 8 ends with a pair of hooks 11, each consisting of a tooth 12 presenting a slanted surface 13 extending outward toward the end of the sleeve itself. In the interior, comprised between the tooth 12 and the area near the flange 10, there is a cylindrical space 14. Within this pace there is a cylindrical spring 15, one end of which rests against the beat 16 belonging to the sleeve 8, while its other end rests against the rim 17 which constitutes the end of cylinder 2 into which plunger 4 is inserted. In the resting position, i.e. when the syringe is new and has not been used yet, as can be observed in Fig. 1, spring 15 is compressed within the annular space 14 and cylinder 2 is kept in its position by the hooks 11 which prevent it from being pushed in the direction opposite the needle; the needle is protected by a cap 30 whose shape and function belong to the known technique. In order to prevent accidental openings due to the sprea- ding apart of the hooks 11, the new syringe is provided with a safety bushing 18, having an essentially cylindri- cal, innerly hollow shape and it presents a bottom with an opening 19, as can be seen in Fig. 6, extending also along the cylindrical wall, the width of said opening being equal to the diameter of rod 4 in the area of rod 4 itself, which has a narrower section than the rest and extends for a certain stretch from the intermediate flange 20 over an area immediately adjacent to the same and extending toward plunger 3. It is easy to understand that, when in its resting posi- tion, as can be observed in Fig. 1, the safety bushing 18 holds in its interior the hooks 11 and prevents them from opening up and, therefore, from freeing the syringe cylin- der. As soon as the rod 4 of plunger 3 begins to move and to suck in the liquid, as can be seen in Fig. 2, the bus- hing 18 frees itself from the hooks 11, since it is trailed along by the beat 21, because of the difference in the diameter of rod 4 in the indented area 29. Once the disengagement between the safety bushing 18 and the hooks 11 has occurred, the bushing itself can be elimi- nated, or, more frequently, if falls off because of the force of gravity, since its center of gravity is asymmetri- cal in relation to the geometrical axis of the same, so that it is possible for the bushing to fall down. Fig. 3 shows the syringe according to the invention while it is sucking in the liquid to be injected and Fig. 4 shows the final stage of the liquid injection, when plunger 3 reaches the bottom of the cylinder 2. While in this posi- tion, it can be observed that the intermediate flange 20 causes the pair of hooks 15 to spread apart, so that it is possible for cylinder 2 to slide in the direction opposed to that of the needle, since it is pushed by the compressed spring 15, as can be seen in Fig. 5. The condition is thus created, that when the plunger rea- ches the bottom of the cylinder and the injecting operation has, therefore, been completed, the syringe cylinder disen- gages itself and the cylinder slides back in the direction opposed to that of the needle, thereby allowing the needle 6 to enter into the protective sleeve 8. In the area of the sleeve presenting a narrower section 5, before the needle 6, there is an elastic washer 21 which, as can be better observed in Fig 6, has the shape of a truncated cone and presents a set of elastic cogs 23, so that, when the needle 6 slides backwards because it is trailed along by cylinder 2, said washer positions itself within an annular indenta- tion 22 which is present in the inner wall of sleeve 8. It is obvious that any action aimed at pushing again both the rod and the syringe cylinder with the purpose of pushing the needle 6 out of the protecting sleeve 8 is prevented by the presence of the washer 21, whose cogs 23 contrast against the wall 24 formed by the indentation 22. Thus it is impossible to use the syringe more than once for subse- quent injections and it is guaranteed that the needle can never go out of the protecting sleeve 8. Thus it has been seen how the single-shot, disposable syringe according to the invention has reached all the proposed purposes. In fact, it has been seen how the needle withdraws immediately when, after reaching the end of its stroke, the plunger ends its pushing action. It has also been observed how any subsequent attempt at letting the needle out or, at any rate, at re-using the syringe is prevented by the presence of a washer positioned in the indentation belonging to the inner surface of the cylindri- cal protecting sleeve. It is apparent that the invention, such as it has been described, can undergo changes during the manufacturing stage; for instance, it will be possible to change the number or the shape of the hooks holding the syringe cylin- der in position; it will also be possible to change the type of washer or of the elastic means which permits the jamming of the cylinder, should there be an attempt at a subsequent re-utilization. However, all said changes will be considered as belonging to the scope of the invention. such as it is described in the following claims.

Claims

CLAIMS 1) A single-shot, disposable syringe for pharmaceutical use, comprising: - a cylinder (2) within which slides a plunger (3) activa- ted by a rod (4), wherein an injection needle is attached at the end (5) of said syringe having a narrower section; - an injection needle (6) attached to said cylinder; - a cap (30) covering the needle; characterized in that it presents in combination: - a cylindrical sleeve (8) suited to hold in its interior the cylinder of the syringe and to maintain said position through some elastic hooks (11); - an outer flange (8) belonging to the sleeve (8) and made so that the fingers of the hand engaging the syringe giving the injection can rest on it; - a spring (15) or equivalent elastic means positioned between the sleeve (8) and said syringe cylinder (2) - at least one pair of elastic hooks (11) belonging to the sleeve (8) and suited to hold back the lower rim (17) of the syringe cylinder when the syringe plunger (3) has not reached the end of its stroke, the spring (15) positioned between said sleeve and said cylinder being under stress; - an intermediate flange (20) belonging to the rod pushing the plunger and positioned close to the rod-pushing flange (7), said intermediate flange (20) being suited to co- operate with the terminal parts of said hooks, in that it opens them up, thereby unhooking them and causing the syringe cylinder (2) to withdraw from the cylindrical sleeve, because of the elastic return of the spring; - blocking means preventing the further reciprocal sliding between the sleeve (8) and the syringe cylinder (2), after the syringe has drawn back in relation to the sleeve, as soon as the injecting operation has been completed. 2) A syringe according to claim 1, characterized in that the blocking means preventing any further sliding between the sleeve (8) and the syringe cylinder (2) after the first use is an elastic washer (21) arranged around the narrower section (5) of the syringe cylinder (2), between said cylinder and the needle (6), said elastic washer (21) being suited to be restrained within an annular indentation (22) belonging to the inner surface of the sleeve, when the syringe cylinder slides back at the end of the injecting operation. 3) A syringe according to claim 1, characterized in that it presents a safety bushing (18) having an essentially cylin- drical shape, being innerly hollow and with a bottom pre- senting an opening (19) extending also along the cylindri- cal wall, its width being such that it is positioned along the area (29) of the plunger-pushing rod having a narrower section, the inner cylindrical surface of said bushing restraining the outer surface of said at least one pair of hooks (11) when the syringe is not used, said bushing (18) disengaging itself from the restriction of said hooks and coming off the syringe when the plunger rod of the syringe moves for the suction action. 4) A syringe according to claim 1, characterized in that the safety bushing (18) has a center of gravity which is considerably off center in relation to the geometrical axis of said bushing, so as to fall off the syringe because of the force of gravity when it is free from the hooks of the sleeve (8).