SINGLE-USE SAFETY SYRINGE PROVIDED WITH RETRACTILE NEEDLE AND DEVICE PREVENTING IT FROM BEING REUSED

Abstract: Single-use safety syringe comprising a cylindrical body (1) provided with an opened, frusto-conical fore end (2), a sliding plunger (5) within said body, a needle (9) coupled to said plunger and assuming a retracted position in which it is received in said cylindrical body and an operative position in which it projects from said fore end to make an injection, self-locking means preventing the syringe from being filled again after the first injection, and means for retracting and locking under control said needle in the cylindrical body once made the injection.

Description: SINGLE-USE SAFETY SYRINGE PROVIDED WITH RETRACTILE NEEDLE AND DEVICE PREVENTING IT FROM BEING REUSED. The present invention relates to a single-use syringe provided with a retractile needle and a self-locking device preventing the syringe from being filled again after the first injection. As it is well known to the medical staff the conventional glass syringes provided with a needle which can be separately applied thereto have been for some time almost completely replaced by the socalled single-use syringes of the disposable type which are of more practical use and do not need any sterilization, thus providing greater reliability of sterility by the use. In said syringes, generally of plastic material, the needle integral with the body of the syringe is protected by a cap to be removed before and applied after having made the injection. However, the protection cap gets frequently lost or is not applied any more to the needle as this ope¬ ration involves the risk of contacting the used needle with the danger of eventual infection. Even if the protection cap is applied again to the needle, it can be accidentally removed so that the danger of infection still remains. This invention seeks to provide a solution to the above mentioned problem by means of a syringe providing the requested easeness of use, protection and inacces¬ sibility of the needle once made the injection. According to the invention there is provided a syringe comprising a cylindrical body provided with a frusto-conical fore end, a plunger sliding in said cylinder body, a needle contained and protected in said cylindrical body, said needle projecting under control of the plunger from said fore end to reach an operative position, in which it is integral with the body of the syringe, and returning still under control of said plunger to the protected position where it is locked. According to a preferred embodiment the locking of the needle both to the body of the syringe and the plunger is made easier and reliable, and above all the syringe is prevented from being used again after the first injection. This has been achieved by providing the base of the needle with engaging means which at the end of the first injection, when the plunger is at the end of its stroke, locks automatically the needle to the plunger and constrains it to enter the body of the syringe again if the plunger is retracted. The invention will be now described with reference to the annexed drawing showing a preferred embodiment of the invention as an illustrative non-limitative example. In the drawing: Fig. 1 shows the three members forming a syringe according to the invention; Fig. 2 shows the syringe with the needle retracted under safety conditions; Fig. 3 shows an alternative embodiment of the syringe according to the invention; Figs. 4, 5 and 6 show three different embodiments of the device preventing the syringe from being re-used. With reference to Fig. 1 numeral 1 designates a body of a syringe of proper size and suitable material which is provided with a fore end or frusto-conical spout 2 opened outwardly and provided with inner L-shaped grooves 3. At the other end, body 1 carries the hold flange 4. Sliding within body 1 of the syringe is a plunger 5 integral with rod 6 provided at its end with thrust disc 7 cooperating with hold flange 4 so that the plunger can slide within body 1. At the front side plunger 5 carries concentrically a frusto-conical end 8. The third member of Fig. 1 is a needle 9 integral with a frusto-conical joint 10 having outer dimensions corresponding to the inner cavity of end 2. Joint 10 is provided inside with a frusto-conical seat 11 shown in phantom and having dimension corresponding to the end 8. Of course, the frusto-conical seat 11 communicates with needle 9. Beside the metallic socket 12 at the base of the needle there are provided projecting pins 13 facing grooves 3 of spout 2. In Fig. 1 the projecting pins 13 and the corresponding L-shaped grooves are four but it is evident that the number thereof may by varied. In operation, the syringe devoid of its packing appears as in Fig. 2 with needle 9 integral with plunger 5 because the frusto-conical joint 10 is applied to the end 8. Under these conditions needle 9 is received within body 1 of the syringe, i.e. in safety position. By pushing plunger 5 forward, needle 9 comes out of the fore spout 2 until the projecting pins 13 are introduced into grooves 3. At the end of the longitudinal length of the grooves 3 the plunger is rotated briefly anticlockwise so that pins 13 enter the cross length of said grooves (bayonet joint), and needle 9 is locked in spout 2 as shown with dashed lines in Fig. 2. Under these conditions plunger 5 can be retracted and disengaged from the needle which remains projected outwardly, and the syringe is used in the usual way to suck in the substance to be injected. After the injection plunger 5 is pushed forward up to the end of its stroke, whereupon it is rotated this time clockwise so that pins 13 are disengaged and needle 9 is pulled within body 1 of the syringe under safety condition. Now plunger rod 6 ca be broken at its prede¬ termined break point designated by 14 in Fig. 2, and needle 9 remains locked in a position inaccessible from the outside. Instead of pins 13 engaging grooves 3 the coupling between needle and plunger can be provided by helical projection 15 shown by dashed lines and formed on the frusto-conical joint 10 of the needle, said projection being introduced into a corresponding helical groove 16 or the like formed in spout 2. According to an alternative embodiment plunger 106 carries a rubber gasket 124 abuting against a disc 125 integral with a generally cylindrical fore end 108 provided with radial cuts 118 allowing the fore end to be opened like a corolla. Needle 109 is integral with a joint 110 having outer dimensions corresponding to the inner cavity of projection 102. Joint 110 is provided inside with a seat 111 the size of which corresponds to the fore end 108. Formed on the inner walls of seat 111 (Fig. 3) are projections or teeth 112 intended to engage corresponding notches or grooves 113 formed on fore end 108. Seat 11 communicates with needle 109 through a conical projection 114 hanging from socket 115 at the base of needle 109. Socket 115 is provided with tabs 116 radially projecting and facing grooves 103 and projections 104 in spout 102. Projecting tabs 116 and the corresponding projections 104 are in a number of three but it is evident that this number may be varied. In operation, the syringe appears as in Fig. 3, needle 109 being integral with the body 100 of the syringe, plunger 106 being retracted. This position is reached by first pushing plunger 106 forward so that the needle can project from fore spout 102 and tabs 116 can slide in grooves 103 and engage projections 104, whereupon the plunger is rotated clockwise or anti¬ clockwise so that tabs 116 can abut against and be retained by projections 104. In such a position the syringe is ready to be filled up and used to suck in the substance to be injected and to make the injection. During the injection plunger 106 is pushed forward up to the end of the stroke and the conical projection 114 of the needle enters fore end 108 of the plunger and spreads apart the walls thereof so that notches or grooves 113 engage teeth 112 of joint 110 of the needle which is now integral with the plunger, thus preventing the syringe to be filled up again. Therefore the plunger is now rotated anticlockwise or clockwise to disengage tabs 116 from projections 104 so that- needle 109 can return within body 100 of the syringe under safety conditions. Plunger rod 106 can be broken at its predetermined break point as in the preceding ambodiment so that needle 109 is locked in its position inaccessible from the outside. The outer surface of socket 115 and the inner surface of spout 102 can be knurled to increase the adherence beween needle and spout of the syringe. In Figs. 4, 5 and 6 three alternative solutions of the above described coupling joint between needle and plunger are shown. In the first case (Fig. 4) the widening member is suitably shaped to engage a corre¬ sponding seat formed in fore end 108. In the second case (Fig. 5) a saw-teeth coupling has been used. In the third case (Fig. 6) a geometric dovetail coupling has been chosen. This invention has been shown and described according to a preferred embodiment but it should be understood that construction modification can be made without parting from the scope of this industrial invention.

Claims: CLAIMS 1. Single-use safety syringe characterized in that it comprises an outer cylindrical body provided with a frusto-conical end spout, a needle received under safety conditions within said cylindrical body, and a plunger operatively connected to said needle both to project the latter out of the syringe to make the injection and to return the same into said protection cylindrical body after the injection. 2. The syringe of claim 1, characterized in that after the injection the needle is locked in the body in its retracted position by breaking the plunger rod at a predetermined break point. 3. The syringe of claims 1 and 2, characterized in that the coupling between needle and plunger is provided by the introduction of a frusto-conical fore end integral with the plunger into a corresponding inner cavity formed in a joint located at the base of the needle and having in turn form and size corresponding to the inner cavity formed in said end spout of the syringe body. 4. The syringe of claims 1 to 3, characterized in that the coupling of the needle in the operative position and the disengaging of the plunger is provided by .a plurality of projecting pins located at the top of said frusto-conical joint and introduced in corresponding L-shaped grooves formed in the spout. 5. The syringe of claims 1 to 3, characterized in that the coupling means between needle and plunger is a helical projection formed on said joint and introduced in a corresponding helical groove formed in the spout. 6. The syringe of claims 1 to 5, characterized in that the frusto-conical surfaces of the fore end, the joint and the spout are tight and coaxial to the axis of the syringe body. 7. The syringe of claims 1 to 6, characterized in that the predetermined break zone or line is located near the head of the plunger so that the needle can be locked within the body of the syringe in safety position not accessible from the outside. 8. Single-use safety syringe according to claim 1, characterized in that there is provided a- locking means which at the end of the first injection rigidly connects the needle to the plunger so as to prevent the syringe from being filled again. 9. The syringe of claim 8, characterized in that such coupling means is a widening member projecting downwards from the socket of the needle in the inner seat of the needle joint, said member entering a corresponding cavity of the fore end of the plunger, when the latter is at the end of its stroke, so that the walls od said cavity are widened apart and engage corresponding projections or teeth formed on the inner walls of the needle joint. 10. The syringe of claims 8 and 9, characterized in that the coupling of the needle in the operative position and the disengaging of the plunger is provided by a plurality of projecting tabs located at the base of the needle and at the upper end of said needle joint, said tabs abuting after being rotated against corresponding projections formed within the spout. 11. The syringe of claims 8 to 10, characterized in that knurled surfaces are provided at the base of the needle and on the inner wall of the end spout of the syringe body. 12. The syringe of claim 8, characterized in that the surfaces of the fore end of the plunger and the surfaces of the needle joint are provided with teeth cooperating with one another like saw teeth. 13. The syringe of claims 8 and 9, characterized in that the coupling between the widening member and the fore end of the plunger is provided by a dovetail coupling. 14. Single-use safety syringe provided with a retractile needle according to claims 1 to 13 substan¬ tially as described and illustrated in the annexed drawing.

Inventors: ROSSI LUCIO, ROSSI, LUCIO
Applicants: ROSSI LUCIO, ROSSI, LUCIO
Application year: 1990
Main classification: A61M5
IPC codes: A61M5