MXPA01006632A

MXPA01006632A - Injecting syringe

Info

Publication number: MXPA01006632A
Application number: MXPA/A/2001/006632A
Authority: MX
Inventors: Theodor Schottli
Original assignee: Schoettli Theodor
Priority date: 1999-01-08
Filing date: 2001-06-27
Publication date: 2002-03-26

Abstract

According to the invention the plunger head (11) of the injecting syringe is connected to the shaft (15) by fine links (29) which break at the very latest at the end of the injection process. The plunger head (11) can no longer pulled back and is lost in the syringe barrel (3) so that the syringe (1) cannot be reused.

Description

SYRINGE FOR INJECTION Description of the invention The object of the invention is a syringe for injection according to the preamble of claim 1. Syringes for injection are known in many embodiments. They comprise a cylinder of the syringe with a coupling device for an injection needle and a piston with a plunger head and a plunger rod, as well as a thumb plate for actuating the plunger. These injecting syringes are not only used by qualified personnel, but they are increasingly used for the injection of narcotics and, as a result, they reach into the hands of unqualified people who do not act with care when it comes to sterility. For this reason, injecting syringes with which the first use is indicated or that should only be able to be used only once, have been made known. The possibility of only being able to use the syringe only once, in addition to protecting drug addicts also protects other patients, especially in underdeveloped countries, from coming into contact with contaminated blood from an already used syringe. EP-0438453 discl a syringe to be injected, the piston head of which has an axial bore which is cl off from the bottom side of the piston by a disk whoutline forms a theoretical breaking point. Alternatively to a disc with a theoretical break point it is also known from the same publication to insert a ring with a central theoretical break point into the bottom of the plunger. On the dorsal side of the cone of the syringe on which the injection needle is clogged, a blade protruding inside the stroke path of the cylinder is configured, which when the syringe is completely emptied, that is, when displacing the head of the plunger completely down, separates the disk from the bottom of the plunger along the theoretical break point '. This prevents that a medicament can be sucked again, since due to the rupture of the bottom of the plunger a vacuum can no longer be lifted inside the syringe for injection. This known injection syringe suffers from the disadvantage that it is necessary to overcome a palpable resistance to break the bottom of the plunger. Therefore, skilled drug addicts or skilled medical personnel in hospitals in underdeveloped countries have no difficulty emptying the contents of the syringe, to inject only so much so that a rupture or perforation of the bottom of the plunger does not occur. Consequently, it is possible to reuse the syringe as many times as desired. From US-A 5,000,735 a syringe for injection is known, the plunger head of which is made of rubber and is fitted over an extension of the plunger. The connection of the piston head with the extension of the piston is made through a separate support ring with radial fasteners facing inside. It is possible to extend and compress the support ring by virtue of a slit-like opening. This known injection syringe suffers from the disadvantage that the plunger is comp of several individual components. Due to this, manufacturing and assembly costs are unnecessarily high. In addition it must be difficult to assemble the support ring, the plunger head and the extension of the plunger without breaking it by bending the obturator. US-A 4,950,240 also discl an injecting syringe whplunger is comp of several parts. The plunger head is preferably made of rubber and has a hole open upwards. A flat, annular rod plate with two radially oriented bars facing the inside connected to this bar plate through hinge points is placed on the plunger head so that the bars partly cover the opening of the hollow. On the inside of the hollow is a cylindrical, flat reactor head, which through a long cylindrical reactor rod is inserted into the opening of a break ring placed on the underside of the drive rod. In this, the rod of the reactor is guided through a central opening between the bars of the bar plate. A disadvantage of this known injection syringe resides in that again it is necessary to manufacture and assemble several parts. The manufacturing and assembly costs of a syringe of this type are relatively high. In addition, there is a risk that when the individual parts are assembled, the bars of the bar plate are bent or broken. It is even questionable whether in practice it is actually possible to assemble the minimum of four necessary parts. In US-A 5, 163, 908 another syringe for injection is disclosed. A cone is placed on top of the plunger head, on the tip of which sits a support with a spherical end. The anterior end of the rod is divided into several closely spaced segments by cuts extending radially outward. In the center of the front end a central opening is manufactured which houses the spherical end support. When injecting, the anterior end of the rod is pressed against the cone and breaks with this in a multitude of individual segments. A disadvantage of this injecting syringe is that several parts are required for the manufacture of the plunger, the manufacturing costs being correspondingly high. Furthermore, it is not possible to manufacture the rod that is described in the application through the injection molding process. The task of the present invention is now to refine a syringe for injection so that it is impossible to suck fluid once it has been used only once. This problem is solved by a syringe for injection with the features of claim 1. Convenient refinements of the invention are defined in the dependent claims. The plunger head configured in accordance with the invention breaks apart from the piston rod during the injection process, or at the latest at the end of the injection process, and it is no longer possible to retract it. It remains captive in the cylinder of the syringe. In the design of the syringe according to the invention with connecting pieces that are on the lateral surface of a truncated cone, it is possible to design the breaking load with different magnitude as a function of the direction of displacement of the syringe plunger. This allows to suck the liquid without running the risk of breaking the joint pieces. On the other hand, during the subsequent injection, the connecting pieces are already broken with a few Newton, for example 7-10, of thrust force. This does not impair the function of the syringe, since the contents of the syringe can nevertheless be expelled. The end of the rod pushes in each case to the head of the piston forward. The end of the rod then abuts the sealing cap that covers the end of the bore. The manufacture of the syringe is economical, that is, both the cylinder and the piston and, in case the piston comprises a rubber seal, also the rubber cap, since it is only necessary to manufacture and assemble two or three parts . The invention is explained in more detail on the basis of the exemplary embodiments illustrated. They show: Figure 1 a perspective representation of a disposable syringe with the plunger head partially pushed forward; 2 shows a longitudinal section through a syringe with the body of the piston in the starting position, FIG. 3 a longitudinal section through the syringe with the piston head fully pushed forward, and separated of the rod, figure 4 a cross section through the head of the plunger and the end of the rod along the line IV-IV of figure 5, figure 5 a longitudinal section through the head of the plunger and the end of the rod, figure 6 a longitudinal section through the head of the piston in another refinement of the invention, figure 7 a longitudinal section through the head of the piston in another refinement of the invention, figure 8 a longitudinal section through a syringe with the plunger body in the starting position, without additional sealing cap, FIG. 9 is a view of a plunger of another embodiment of the invention. In the perspective pictorial representation according to FIG. 1, a disposable syringe is designated with reference symbol 1. It comprises a cylinder 3 of the syringe with a coupling device for an injection needle (not in place), for example a needle cone 5, as well as two radially projecting gripping wings 7. Inside the cylinder 3 of the syringe is represented a plunger 9 of the syringe partially pushed forward, at the front end of the rod is placed a head 11 of the plunger and at the rear end of the rod is molded a saucer 13 for the thumb . Between the head 11 of the plunger and the saucer 13 for the thumb there is a rod which, for example, has a cross section in the shape of a cross. Both main parts, the cylinder 3 of the syringe and the plunger 9 of the syringe are made of synthetic material by injection. At the head 11 of the plunger an axially extending bore 17 is produced which passes through it completely (compare figures 2 to 7) or only partially (figures 8 and 9). In the first embodiment, a gasket 19 which preferably has the shape of a cap encloses the periphery and the front bottom surface of the head 11 of the piston. The gasket 19 in the form of a cap extends over at least a part of the periphery 20 of the sealing piston 11, and there it is embedded within a surrounding slag 21 (compare figure 5). The cross-shaped rod 15 has at least in the front section a diameter that is smaller than the diameter of the bore 17. In a design of the invention, a disk 25 is placed on the end of the rod 15 whose diameter it is equal to or greater than the diameter of the bars 23 of the rod 15, but nevertheless smaller than the diameter of the perforation 17. Between the periphery of the disc 25 or of the front section 27 of the plunger which preferably has a smaller thickness and the perforation produces a gap The connection between the section 27 of the rod or the disc 25 and the head 11 of the piston is effected by means of thin connecting pieces 29 in the form of wires, wands or film, which extend radially towards the wall of the piston. the perforation 17 from the bar 23 of the section 27 of the rod or from the periphery of the disk 25, and connect with it. The connection of the connecting pieces 29 of round or polygonal cross section can be made at the end of the bore 17 or axially displaced to the interior of the latter. The strength of the connecting pieces 29 is calculated so that when a pre-established axial force is exceeded, for example from ION, they are cut off by the rod 15 or the disc 25. A more detailed explanation of this process will be made during the description of the operation . Within the stroke path of the cylinder 3 of the syringe, at a distance from the bottom of the syringe barrel that is greater than the axial extension of the head 11 of the plunger, it is possible to form a peripheral rib 33 protruding into the interior of the stroke path of the cylinder 3 and consequently of the trajectory of displacement of the head 11 of the plunger, thus reducing its cross section. The radial extension of the bead 33 is very small and is a function of the diameter of the cylinder 3 of the syringe.

In the design of the invention according to figures 6 and 7, the connecting pieces 29 have a square cross section, the first edge 37 of the connecting pieces facing the bottom of the plunger head extending inclined. The second edge 39 remote from the bottom of the plunger head can extend parallel to the bottom of the plunger head or parallel to the first edge 37. The connection regions of the connecting pieces 29 to the head 11 of the plunger and to the section 27 of the plunger The rod or the disc 25 placed on the section 27 of the rod can extend parallel or - as shown in the examples of FIGS. 6 and 7 - the perforation 17 can have a section 39 of conical development in the region of the connecting pieces 29 Similarly, it is possible for the periphery of the disk 25 to be configured in such a way that it develops conically, that is to say that the disk 25 has the shape of a truncated cone (FIG. 6). In the design of the invention according to FIG. 8, an additional elastic seal is not placed on the head 11 of the piston, but the head 11 of the piston abuts its periphery directly with the wall of the cylinder 3 of the syringe. The section 27 of the rod is again connected to the head 11 of the piston by means of fine connecting pieces 29, where a blind bore 17 is formed in the head 11 of the piston in which the section 27 of the rod can penetrate after the breaking of the rods. connecting pieces 29 and hitting the bottom 28. In the design of the invention according to FIG. 9, a piston head 11 is shown at the end of the rod, the periphery of which abuts in a sealed manner directly with the wall of the cylinder of the syringe. The connection between the head 11 of the plunger, which in this case is configured in the form of a disc, and the section 27 of the rod is effected, for example, by means of three legs 30 which, on the one hand, are fixedly connected to the shaped part. disc of the head 11 of the plunger, and on the other side in each case by a connecting piece 29 with the front end of the section 27 of the rod, or with the disc 25. The length of the legs 23 preferably corresponds to the distance between the disc 25 and the lower end of the upper part of the rod 15. The manner of operation of the disposable syringe 1 is explained in more detail below. When manufacturing the syringe 1, in the case of the three-part mode after injection molding the individual parts, the seal 19 is sealed on the head 11 of the plunger and then inserted by pushing the plunger 9 of the syringe into the interior of the cylinder 3 of the syringe, and this only to where the board still does not reach the bead 33, that is, there is no contact between both parties. The insertion of the plunger 9 of the syringe into the cylinder 3 of the syringe is commonly carried out by means of a mounting or processing apparatus, so that it is possible to adjust very precisely the position of the plunger 9 of the syringe. In the case of the design of the invention according to FIGS. 8 and 9 operating without the sealing cap 19, after the manufacture of the piston 9 of the syringe, it is directly introduced, pushing it into the cylinder 3 of the syringe. But it is not inserted beyond where the leading end of the plunger head arrives at the beginning of a conical region A (see FIG. 8), as soon as cylinder 3 of the syringe has been provided with this type of region A having a Alpha conical angle. In the case of an uninterrupted cylindrical syringe barrel 3 it is possible to push the plunger 9 to the bottom 4 of the plunger. The user of the syringe 1 fills it in the conventional manner, retracting the plunger of the syringe. After venting, by blowing out the air from the front part of the cylinder 3 of the syringe, the injection is executed, in which, for a complete emptying, the head 11 of the plunger is pushed until it hits against the bottom 4 of the cylinder 3 of the syringe on the end of the side of the needle. In the last millimeters of the advance, when passing the bead 33 in case one has been provided, or when penetrating the conical region A and / or when squeezing the last remnant of the liquid, the connecting pieces 29 are broken due to the greater resistance , and the rod 15 slides forward through the perforation 17 or between the legs 30 (figure 9) and hits the bottom 28 of the perforation 17 or the legs 30 with the end of the rod. In this way, it is possible to push the head 11 of the plunger until the end of the stroke in the bottom 4 of the cylinder 3 of the syringe, in spite of having severed the connecting pieces 29. It is impossible to suck fluid again. With it, the disposable syringe 1 becomes unusable.

Claims

1. Syringe for injection with a cylinder of the syringe comprising a coupling device for placing an injection needle formed at the anterior end, a pair of grip wings formed at the posterior end, a syringe plunger which is guided along of the stroke path of the syringe barrel and comprising a rod having a plunger head with a surrounding peripheral sealing surface and a thumb plate, characterized in that the head of the plunger is connected to the rod by connecting pieces in the shape of of thread, wand or film, and because in the head of the plunger support elements are provided for the end of the rod.

Injection syringe according to claim 1, characterized in that an axially extending bore is formed in the head of the plunger, because the section of the rod at its end on the side of the plunger head has a cross section that is smaller than the section cross section of the bore at the end of the rod, and because the end of the rod on the side of the plunger head is connected to the plunger head by the connecting pieces.

Syringe for injecting according to claim 1, characterized in that support legs are formed on the head of the piston, at the ends of which the connecting pieces that connect to the rod are connected.

Syringe for injection according to one of claims 1 to 3, characterized in that the connecting pieces are arranged between the rod and the head of the piston so that they substantially extend radially.

Syringe for injection according to claim 4, characterized in that the connecting pieces are fixed to a disk formed or placed at the end of the rod.

Syringe for injecting according to claim 5, characterized in that the edges of the joining pieces approach a greater radial distance from the rod or disc, and the contact surface with the plunger head is smaller than with the disc, or because the connecting pieces are configured so that they extend with a frusto-conical surface.

Syringe for injection according to one of claims 2, 4 to 6, characterized in that the connecting pieces are connected to the head of the piston at the end of the bore that is on the side of the rod or inside the borehole. an axial distance from the end that is on the side of the rod.

8. Injection syringe according to one of claims 6 to 7, characterized in that the perforation and / or the periphery of the disk develops conical at the connection point of the connecting pieces. Syringe for injecting according to one of claims 2, 4 to 6, characterized in that the seal extends axially on at least one part of the periphery of the sealing piston, and in that the seal is configured in the form of a cap. Syringe for injection according to one of claims 1 to 9, characterized in that at a distance from the leading and / or the trailing end of the stroke in the cylinder of the syringe a total or partially surrounding bead is formed which narrows the cross section and / or at the anterior end a conical tapering section is formed.