MXPA00007068A - Disposable safety syringe - Google Patents

Abstract

A needle-covering sleeve (14), slidably fitted on the syringe barrel (1), is held in its retracted rest position by means of retaining tongues (10), which hook it at its rear rim (13). At the end of the injection stroke of the plunger (2), a rear flange (8) of the stem (3) of the plunger (2) radially opens the retaining tongues (10) apart, which release thereby the needle-covering sleeve (14). Then, the latter is axially advanced by means of a spring (16), to an advanced safety position, in which it entirely covers the needle (5) and is fastened to a sleeve-clamping ring (18), which is provided at the fore end of the syringe barrel (1). To this purpose, the sleeve-clamping ring (18) has peripheral elastic retaining tongues (19) which interact with matching retaining teeth (20) on the inner part of needle-covering sleeve (14) and prevent any axial backward movement of the needle-covering sleeve (14). Further, the sleeve-clamping ring (18) is a stop abutment, cooperating with an inner projection of the needle-covering sleeve (14) and preventing any further axial forward movement of such sleeve.

Description

DISPOSABLE SAFETY SYRINGE DESCRIPTION OF THE INVENTION The present invention relates to a disposable safety belt, comprising: a) a cylindrical body of jing; b) an injection needle, which is integral with a needle holder, which is attached to the forward end of the indian body of the eringa; c) a plunger that is slidable in the cylindrical body of the jig and has an injection segment extending from the filling position of the retracted jigsaw to an advanced jigging position, and is adjusted in its back with a manually pullable body, ejected out of the cylindrical body of the erringa through the open end thereof; d) a sleeve covering the needle, which is axially attached to the cylindrical body of the jig, to be slipped from a retracted rest position, in which it left the exposed needle, to an advanced safety position , in which it completely covers the needle; e) means for interacting with each other, which are provided on the rear side of the cylindrical body of the jig and on the rear side of the sleeve covering the needle, and are initially coupled together to retain the sleeve covering the sleeve. needle in its retracted rest position, considering that they are automatically decoupled from one another by the plunger body, in the last portion of the injection segment of the plunger, thereby releasing the sleeve covering the needle; f) a spring, interposed between a spring support projection on the rear end of the cylindrical body of the jig and a spring support projection, inside the sleeve covering the needle, which tightens the sleeve covering the needle a, once it is released from the hook-like means, towards its advanced safety position, first having it elastically adhere to the patient's body, and then advancing it progressively, when extracting the needle from the patient's body, at the end of the injection, until it completely covers the extracted needle; g) fastening means that automatically lock the sleeve covering the needle in its advanced safety position, preventing it from moving axially in any direction; h) the means for securing the sleeve covering the needle in its advanced safety position are supported and / or formed at least partially in a mounted sleeve clamping ring, which is provided and preferably mounted and fitted in the front end of the cylindrical body of j eringa; i) one or more retention tabs, which are preferably formed in one piece with the sleeve clamping ring and which extend forward in the axial direction by their free front ends, the retention tabs of which can be moved radially elastically inward, that is, towards the longitudinal axis of the jingling; k) one or more retaining teeth provided on the inner part of the sleeve covering the needle, each associated with a tab for retaining the sleeve clamping ring, each of the retention teeth which is provided with a rear flank which is substantially transverse to the horizontal shoulder of the jig and interacts with a supporting surface with the free end of the retention tab associated therewith, and with a leading flank, which is forwardly inclined in shape. radially outward and interacts as a diverting surface with the free end of the retention tab associated therewith; 1) a radial stop projection, which is provided at the rear end of the sleeve clamping ring and interacts as a splice with an internal stop projection of the sleeve covering the needle; m) all this in such a way that, in the final portion of the front segment of the sleeve covering the needle, the retaining teeth or the same push elasticly and radially, by means of its inclined front flanks, the one or the associated retaining tabs inwards, passing beyond these and allowing it to be elastically adjusted radially outwards, to couple its free front ends with the posterior transverse flanks of the teeth associated retention, while the internal stop projection of the sleeve covering the pin makes contact with the rear splice projection of the sleeve clamping ring. A disposable safety belt of this type is known from US-A-5 562 626, WO-A-93/00949 and EP-A-0 467 1 73. In the known disposable safety locks. from these documents, the sleeve covering the needle has an internal section profile around it and a profile of uniform external section around it, and the retaining teeth cooperating with the retaining tabs of the ring Cuffs protrude into the internal circular section profile of the sleeve covering the needle, thus determining a corresponding external diameter of said sleeve. With respect to those known syringes, the disposable safety belt according to the invention is characterized in that the retaining tabs of the sleeve-holding ring are slidably coupled by their free forward ends in internal longitudinal grooves in correspondence with each other. of the sleeve covering the needle, in whose grooves, its respective retaining teeth are provided, and the internal longitudinal grooves of the sleeve covering the needle are formed in corresponding external longitudinal ribs of the sleeve covering the needle. Such characteristics, and several more, of the invention, as well as those that are derived from it, will be apparent from the following description of the preferred embodiment, illustrated without restriction in the accompanying drawings, in which: Figure 1 is an exploded perspective view of one embodiment of the syringe according to the invention. Figure 2 is a side view of the rear end of the cylindrical body of the syringe. Figure 3 is an axial sectional view of the trailing end of the cylindrical body of the syringe, as taken on line 111-111 of Figure 2. Figure 4 is an axial sectional view of the sleeve clamping ring provided in FIG. the front end of the cylindrical body of the syringe. Figure 5 is a side view of the syringe of Figure 1, with the sleeve covering the needle in its retracted rest position. Figure 6 is an axial section view of the syringe as taken on line VI-VI of Figure 5, also in the retracted rest position of the sleeve covering the needle. Figure 7 is a side view of the syringe, similar to that of Figure 5, although with the sleeve covering the syringe in its advanced safety position, when the injection has been made and when the needle has been extracted from the body of the syringe. patient. Figure 8 is an axial sectional view of the syringe as taken on line VIII-VIII of Figure 7, also in the advanced safety position of the sleeve covering the needle. The disposable safety syringe according to the invention comprises a cylindrical body 1, in which the plunger 2 is slidable in a fluid-tight manner. The plunger 2 is connected to a body 3, which extends axially in the cylindrical body of the syringe 1 and is pushed out of the latter, through its open rear end. At the tapered tapered front end 101 of the cylindrical syringe body 1, a needle-bearing member 4 is attached in a fluid-tight manner to the injection needle 5 which is fitted therein. The internal space of the cylindrical body of the syringe 1 communicates with the tubular injection needle 5, through a hole formed in the needle holder 4. The needle 5 is initially protected by a cover 6., fitted on the needle carrier 4. The needle carrier 4 and the needle 5 are omitted in the sectional view of Figure 6. The cylindrical body of syringe 1 is provided, at its rear end, with a hollow widened head 7. , open at its rear, wherein a flange 8, for example having a circular shape, and is provided on the body 3 of the plunger 2 housed near the rear end of such body 3. On two diametrically opposite locations, on the wall lateral of the head 7 of the cylindrical syringe body, two retaining tabs 10 are formed by means of the cuts 9, extending forward in the longitudinal direction beyond the leading edge of the head 7. The retaining tabs 10 are provided, at its forward free ends, with radially internal teeth similar to hook 12 which interact with a radially external contraplente similar to associated hook 13, placed on the upper edge of a m Anguito covering the needle 14, which is provided with two diametrically opposed radial tabs 114 and is axially slidable fitted on the cylindrical barrel of the syringe 1. Normally, in the resting condition, the retaining tabs 10 are in one position radially retracted, i.e., substantially parallel to the longitudinal axis of the syringe and in which its hook-like teeth 12 are coupled with their respective counterparts to respective hooks 13 of the sleeve covering the needle 14, as shown in Figure 6. Without However, said retaining tabs 10 can be elastically opened and arrive at a position in which their hook-like teeth 12 are decoupled from their associated hook-like counterparts 13 of the sleeve covering the needle 14, as shown in Figure 8. .

In order to obtain said separated radially open position of the retaining tabs, each retaining tab 10 is provided, on its radially internal side, with a projection 15, which protrudes into the hollow head 7 of the cylindrical body of syringe 1 and which It has a sawtooth profile, with a surface that, when viewed from the front to the front, is tilted inward, ie towards the central axis of the syringe, and ends in a biased stage. These internal projections 15 of the retaining tabs 10 interact with the flange 8 the body 3 of the plunger 2 as described below. For a certain portion 214 of its rear end portion, the sleeve covering the needle 14 has an internal diameter that is larger than the external diameter of the cylindrical body of the syringe 1, and the hollow space therebetween houses a coil spring 16 which rests by its upper end, as seen from the outside, against the annular bottom of the enlarged head 7 of the cylindrical barrel of syringe 1, and by its front end against a spring support projection 117 that is provided inside the sleeve covering the needle 14 and may consist of the annular bottom of the rear widened part 214 of the sleeve covering the needle 14 or, as shown, of a bearing 170 inserted in the broadening and having on one end side, an annular edge projecting radially towards inside, and positioned to form such a spring support projection 17. The remaining portion of the sleeve covering the needle 14 is provided with two longitudinal ribs dia. Metrically opposite external 314, extending from the annular bottom of the rear widened portion 214 of the sleeve covering the needle 14, to a little before its leading end. On the outer surface of the outer longitudinal ribs 314 are preferably substantially in line with the outer surface of the rear widened portion 214 of the sleeve covering the needle 14. Each outer longitudinal rib 314 of the sleeve covering the needle 14 forms a groove corresponding internal longitudinal 414. A sleeve clamping ring 18 is fitted and mounted on the forward cylindrical end of the cylindrical barrel of syringe 1, and extends forwardly around the tapered tapered end 101 of the barrel of the syringe and around the needle holder 4 fitted on the tapered tapered end 101. This sleeve clamping ring 18 preferably has, on its periphery, two retaining tabs 19, which are made in one piece with said ring 18 and extend in the axial direction, with their free ends that are directed forward. The retaining tabs 19 are located in two radially opposite locations and are radially open, that is to say: inclined forward and radially rearward, while they are elastically mobile radially inwardly. The free front ends of the retaining tabs 19 are engaged in one of the internal longitudinal slots 414 of the sleeve covering the needle 14, formed in the corresponding external longitudinal ribs 314. In each of these longitudinal slots 414 of the sleeve covering the needle 14, a retaining tooth 20 is provided, which is positioned to interact with the free forward end of the associated retention tab 19 of the sleeve clamping ring 18 as described below. Each of the retaining teeth 20 has a rear flank, which is substantially flat and transverse to the axis of the syringe, and a leading flank which is inclined forward and radially outwardly. The rear end of the sleeve clamping ring 18 projects radially from the peripheral surface of the cylindrical barrel of syringe 1 and forms an annular splice 21, positioned to interact with the spring support projection 17 of the sleeve covering the needle 14 as shown in FIG. describe below. The sleeve clamping ring 18 can be fixed in a stable and non-removable manner to the cylindrical body of the syringe 1, for example by means of glue or welding, or it can be adjusted by force on the front end of the cylindrical body of syringe 1 and therefore held removably therein by friction. The sleeve clamping ring 18 can be separated and completely disengaged from the needle carrier 4. However, in the illustrated embodiment, the sleeve clamping ring 18 is mechanically connected to the needle holder 4 and thus to the needle holder 5. , at least in the axial direction. Particularly, the sleeve clamping ring 18 has an internal thread 22, in which the needle carrier 4 is screwed with the help of the external radial fins 104 of its rear edge. The above disposable safety syringe operates as follows. In the initial condition, ie the condition supplied by the user, the different parts of the syringe are in the position shown in Figures 2 and 3. More precisely, the sleeve covering the needle 14 is in a retracted rest position, in which it leaves the needle 5 exposed, and is held and engaged by the retaining tabs 100, which are free and therefore in their radially inwardly inclined position. The retaining tabs 19 of the sleeve clamping ring 18 are separated open and engaged in the front end part of their respective internal grooves 414 of the sleeve covering the needle 14. The coil spring 16 is compressed and fully housed in the enlarged part. 214 of the sleeve covering the needle 14, between the latter and the cylindrical syringe body 1. The retaining tabs 10 are preferably as long as the hook and retain the sleeve covering the needle 14 in a retracted position, in which its rear edge is near the head 7 'of the cylindrical body of syringe 1, whereby the spring is not really visible, and the side flaps 114 of the sleeve covering the needle 14 are placed immediately before the head 7 of the cylindrical body of the syringe 1. The plunger 2 and its body 3 are located in an advanced position, in which the plunger 2 is near the front end of the cylindrical body. syringe 1, although it is still able to move a small segment forward. The rear flange 8 of the body 3 of the plunger 2 is partially inserted in the rear hollow head 7 of the cylindrical body of the syringe 1, although it is stopped in a position, in which it does not come into contact with the internal inclined projections 15 of the tongues of the syringe. retention 10, or touch only said projections 15, without exerting any discernible pressure on them. In the illustrated embodiment, the flange 8 is stopped by means of a cylindrical safety sector 3, which extends outwardly from the hollow cylindrical head 7 of the cylindrical body of the syringe 1, which covers an angle substantially equal to or less than 180 ° , and has two internal retaining tabs 44 that extend transverse and perpendicular to the axis of the syringe, while they are parallel to and are at a distance from one another. These clamping tabs 24 are inserted into the head 7 of the cylindrical syringe body through two corresponding grooves 25, formed in the lateral cylindrical frame of the head 7 and placed one behind the other before the rear flange 8 of the head. body 3 of the plunger 2, thus securing the flange 8 in the aforementioned position, in which it does not interfere with the internal projections 155 of the retaining tabs 10. In the aforementioned securing position, the cylindrical safety sector 23 it is removably attached to the head 7 of the cylindrical body of syringe 1, for example by means of two hook-like side levers 228, made in one piece with the cylindrical sector 23, so that they can oscillate elastically around an intermediate point of their length. Initially, the side levers 28 are hooked by a toothed end thereof to the corresponding external projections of the head 7 of the cylindrical body of syringe 1. Pressing radially on the other end of the side levers 26, these latter are angularly displaced and released from the associated external projections of the head 7 of the cylindrical body of syringe 1, whereby the cylindrical safety sector 23 is decoupled from the head 7. Then, this safety sector can be removed, radially, by pulling its internal clamping tongues 24 out of their respective lateral grooves 25 of the head 7 of the cylindrical body of syringe 1 and thereby releasing the flange 8 of the body 3 of the plunger 2, and therefore the body 3 thereof. . Instructions for use can be provided outside the safety sector of a cylinder 23. Once the cylindrical safety sector 23 is disconnected and the protective cap 6 of the needle 5 is removed, the latter can be introduced, for example, into a vial containing the liquid to be injected and this liquid can be aspirated into the syringe, by withdrawing the plunger 2 to a syringe position, by means of an end head 27 provided at the rear end of the body 3, outside the head hollow 7 of the cylindrical body of syringe 1. When filling the syringe, the injection is made in the usual way, since the sleeve covering the syringe 14 is still hooked and held by the retention tabs 10 in its resting position, as shown in Figure 6, in which it leaves the needle 5 exposed. The side wings 114 provided at the rear end of the sleeve covering the needle 14 are used to retain the cylindrical body of syringe 1 during injection, for example by holding it in the usual manner, by the index and middle fingers of a hand, while that axial pressure is exerted on the rear end head 27 of the body 3 of the plunger 2, for example by the thumb of the same hand. In the final part of the injection segment of the plunger 2, the flange 8 of the body 3 penetrates the hollow head 7 of the cylindrical body of the syringe 1 deeper than before, for example to the bottom of said head, or in any way to a such as to engage and push the inner projections 15 of the retention tabs 10 radially outward, and to open radially, ie to angularly outwardly deflect the retention tabs 10, as shown in Figure 8. are open and separate the retention tabs 10 uncouple and release the sleeve covering the needle 14, which is pushed by the spring 16 and advanced on the cylindrical body of syringe 1 until it is attached by its front end against part of the body of the patient, in which the needle 5 is inserted. Then, while the needle 5 is withdrawn from the patient's body, the sleeve covering the needle is further advanced with respect to the cylindrical body of syringe 1 by the spring 16, until it reaches a final advanced safety position, in which it is covered. in addition completely the needle 5. It also extends beyond the sharpened end thereof, to an extent to prevent the needle from being accessed by a finger, as shown in Figures 7 and 8. In the advanced safety position, the sleeve covering the needle 14 is held axially in both directions by the sleeve clamping ring 188. More precisely, the last part of the segment of the anterior segment by the sleeve covering the needle 14, the internal retaining teeth 20 of the sleeve elastic and radially push, by its inclined leading flank, acting as a diverting surface, the retaining tabs 19 of the sleeve clamping ring 18, by so that the retaining teeth 20 pass beyond their respective retaining tabs 19, which snap outwardly, returning to their rest positions, in which their free front ends are engaged with the rear transverse flanks of the teeth of the teeth. associated retention 20 of the sleeve covering the needle 14. At the same time, the spring support projection 17 inside the sleeve covering the needle 14 arrives or is close to the rear end 21 of the sleeve clamping ring 18, which acts as a stop splice, as shown in Figure 8. Through this In this arrangement, the needle holder clamping ring 18 fits between the internal retaining teeth 20 of the sleeve covering the needle 14 and the spring support projection 17 therein, thereby axially securing the sleeve covering the needle 14 to the Cylindrical body of syringe 1 in both directions in its advanced safety position. When the holding ring of the needle holder 18 is fixed in a stable non-removable manner to the cylindrical body of the syringe 1, the sleeve covering the needle 14 is also fixed in a stable and non-removable manner to the cylindrical body of the syringe 1 and the syringe it has to be intentionally detached for access to the needle 5. When the holder ring of the needle holder 18 is removably fitted on the cylindrical body of syringe 1 and held therein by friction, any attempt to force forward extraction of the sleeve covering the needle 14 causes the holding ring of the needle holder 18 to be axially separated, so that it is removed together with the sleeve covering the needle 14 with the needle 5, the needle holder 4 which is screwed into the needle needle holder holding ring 18. In this way the needle 5 is inaccessibly confined within the sleeve covering the needle 14 slid out of the cylindrical body of the needle. nga 1. Once the injection has been performed, the body 3 of the plunger 2 is automatically secured in both directions to the cylindrical body of the syringe 1 in the advanced position of the plunger 2, ie in its syringe emptying position, avoiding this way any further movement of the plunger 2 and any reuse of the syringe. For this purpose, when the retention tabs 10 of the rear head 7 of the cylindrical body of syringe 1 have been opened and separated and when the sleeve covering the needle 14 has been released interacting in this way with the inclined diverting surfaces of the projections internally of the retaining tabs 10, the rear flange 8 of the body 33 of the plunger 2 passes beyond said projections 15, allowing the retaining tabs 10 to snap radially inwardly and return to their initial rest positions, in that the flange 8 of the body 3 of the plunger 2 now adjusts and is clamped between the annular bottom of the rear head 7 of the cylindrical body of syringe 1 and the step of biased cutting of the projections 1 5 of the retention tabs 1 0 , as shown in Figure 8. Consequently, the body 3 and the rod 2 are also secured. According to a variant embodiment (not shown), in order to automatically prevent the body 3 of the plunger 2 from moving axially backwards from the emptying position of the jig, instead of using the projections 1 5 of the The retaining lugs 10, which provide one or more appropriate reverse securing teeth on the inner wall of the rear hollow head 7 of the cylindrical body of jig 1, the elastic deformation of the securing teeth. reverse and / or tab 8 that is unfolded to allow the tab 8 to pass beyond said teeth. All parts of the frame according to the invention, except the needle 5, are generally made of plastic. Naturally, the invention is not limited to the embodiments described and illustrated herein, since it can vary greatly, in particular with respect to the construction and within the scope of the equivalents, without departing from the guiding principles described above and claimed. then.

Claims (17)

1. CLAIMS 1. A disposable safety syringe, comprising: a) a cylindrical syringe body; b) an injection needle, which is integral with a needle carrier, which is fitted at the tapered front end of the cylindrical syringe body; c) a plunger that is slidable in the cylindrical syringe body having an injection segment extending from a retracted syringe fill position to an advanced syringe emptying position, and is fitted on its back with a body manually pullable, ejected from the cylindrical body of the syringe through the open posterior end thereof; d) a sleeve covering the needle, which is axially fitted on the cylindrical body of the syringe, for sliding from a retracted rest position, in which it leaves the exposed needle, within an advanced safety position, in which it covers completely the needle; . e) Hook-like interaction means, which are provided on the back side of the cylindrical barrel of the syringe and on the back side of the sleeve covering the needle, and are initially hooked together to retain the sleeve covering the needle in its rest position retracted, considering that they are automatically disengaged from one another by the plunger body, in the final position of the injection segment of the plunger, thus releasing the sleeve covering the needle; f) a spring, interposed between a projection of spring support on the rear end of the cylindrical body of the jig and a spring support projection, inside the sleeve covering the needle, which tenses the sleeve covering the spring. the needle, once it is released from the hook-like means, to its advanced safety position, causing it to first adhere elastically to the patient's body, and then advancing progressively, when extracting the needle from the patient's body , at the end of the injection, until it completely covers the extracted needle; g) fastening means that automatically secure the sleeve covering the needle in its advanced safety position, preventing it from moving axially in any direction; h) means for securing the sleeve covering the needle in its advanced safety position are retained and / or formed at least partially by a mounted sleeve clamping ring, which is preferably provided and mounted and fitted on the front end of the cylindrical body of j eringa; i) one or more retention tabs, formed in one piece with the sleeve clamping ring and extending forward in the axial direction by their free front ends, which retention tabs move elastically radially towards inside, that is, towards the longitudinal axis of the jingling; k) one or more retaining teeth provided on the inner part of the sleeve covering the needle, each associated with a tab for retaining the sleeve clamping ring, with one of the retaining teeth that is provided therein. with a rear flank that is substantially transverse to the longitudinal axis of the jig and interacts with a support surface with the free end of the retention tab associated therewith, and with a leading edge, which is lowered forward radially outwardly and interacting as a diverting surface with the free end of the retaining tab associated thereto; 1) a radial stop projection, which is provided at the rear end of the sleeve clamping ring and interacts as a splice with an internal stop projection of the sleeve covering the needle; m) all this in such a way that, in the last portion of the segment of sleeve flange covering the needle, the retaining teeth or the same push elasticly and radially, by means of their inclined front flanksor the associated retaining tabs inward, passing beyond them and allowing them to be elastically adjusted radially outwards, to engage their front ends with the rear transverse flanks of the associated retaining teeth, that the internal stop projection of the sleeve covering the needle makes contact with the projection of the rear connection of the sleeve-holding ring, characterized in that the retention tabs of the sleeve-holding ring are slidably coupled by the ends free-standing in corresponding internal longitudinal grooves of the sleeve covering the needle, in which grooves the respective retaining teeth are provided, and the internal longitudinal grooves of the sleeve covering the needle are formed in corresponding external longitudinal ribs of the covering sleeve the needle. A jingling according to claim 1, characterized in that the sleeve covering the needle is provided, at its trailing edge, with one or more hook-like teeth projecting outward, interacting with one or more hook-like features projecting inwardly complementary, provided in the retention tabs that extend forward in the longitudinal direction of the jig, from a head, located at the rear end of the body of the indi they can move automatically from a radially retracted latching position, in which their teeth are engaged to the associated teeth of the sleeve covering the needle, and hold it in the retracted position of scans, to a radially open release position, in the that its teeth are uncoupled from that of the sleeve covering the needle and releasing said sleeve. 3 . A jingling according to claim 2, characterized in that the rear end of the piston body is provided with means which interact with the retention tabs and automatically cause the tabs to move from their radially retracted engagement position to its radially open release position, at the end of the injection segment of the symbol. 4. A jigging according to claim 2 or 3, characterized in that the head at the rear end of the cylindrical body of j eringa is hollow and is open at its rear and in that the retention tabs are formed by means of cuts in the wall of said head, and they have internal projections that protrude into the space of the hollow head and interact with a flange that is located near the rear end of the body of the head, and can be housed in the head hollow of the cylindrical body of j eringa, taking in it a position of initial rest, in which they do not act on the internal projections of the retention tabs, the latter being in their position radially retracted hooked and a position of more advanced operation, in which they radially push the internal projections of the retention tabs outwards and move these tabs to their radial release position. open entity 5. A syringe in accordance with the claim 4, characterized by removable safety means securing the rear flange of the plunger body in its initial rest position and can be manually removed to enable axial forward movement of the flange and thus of the body with the plunger. 6. A syringe in accordance with the claim 5, characterized in that the removable security means consist of a cylindrical sector that can be adjusted laterally outside the rear head of the cylindrical body of the syringe and removably attached thereto, and whose cylindrical sector has two internal gripping tabs, transverse to the axis of the cylindrical body. syringe, and parallel to and a certain distance from one another, whose clamping tabs penetrate the hollow head of the cylindrical syringe body through corresponding lateral transverse grooves of said head and are placed one behind the other before the body flange of the piston securing it in this way. 7. A syringe in accordance with the claim 6, characterized in that the removable safety cylindrical sector has hook-like means which are press-fitted with the cylindrical syringe body head and are removably releasable therefrom. A syringe according to one or more of the preceding claims, characterized in that it has means to automatically prevent any subsequent axial movement of the plunger body at the injection end, from its corresponding advanced syringe emptying position. 9. A syringe in accordance with the claim 8, characterized in that the means for automatically preventing any further axial movement of the plunger body from its advanced syringe emptying position consisting of one or more reverse securing stop projections which are provided within the rear hollow head of the cylindrical body of syringe on the side wall thereof and are elastically compatible radially outwardly, interacting with the posterior flange of the piston body in such a way that they allow the flange to pass beyond them, at the end of the front segment of the plunger in its position of emptying the advanced syringe. 10. A syringe in accordance with the claim 9, characterized in that the inverse securing stop projections interact with the flange of the plunger body consisting of internal projections of the retention tabs as claimed in claim 4. 11. A syringe in accordance with one or more of the previous claims, characterized in that the sleeve covering the needle is provided, at its rear end, in an angularly staggered position with respect to its hook-like teeth, with lateral fins that can be used to hold with two fingers the cylindrical body of the syringe , during the injection. 12. A syringe according to one or more of the preceding claims, characterized in that the piston body has a thrust head at its rear end. 13. A syringe according to claim 1, characterized in that the sleeve clamping ring is removably fastened to the cylindrical body of the syringe in particular in such a way that it allows it to slide out of the same, and forcibly fit for example, and sustained by friction on the cylindrical body of the syringe. 14. A syringe according to claim 1, characterized in that the needle carrier is independent of and not connected to the sleeve clamping ring. 15. A syringe according to claim 1, characterized in that the sleeve holding ring is stably and non-removably attached to the needle carrier. 16. A syringe according to claim 1, characterized in that the sleeve clamping ring extends forwardly around the needle holder. 17. A syringe according to claims 15 and 16, characterized in that the needle carrier is screwed into an internal threading of the sleeve clamping ring.