The present invention relates to a stopper/piston and to a syringe device including such a stopper/piston.
Stopper/pistons for syringe devices are well known in the prior art. Before the syringe is actuated, the stopper/piston performs the function of a stopper, isolating the fluid contained in the syringe body, and then during actuation, it transforms into a piston, pushing the fluid out of the syringe body, generally through a needle. Generally, the syringe device includes an actuator member, such as a piston rod, that co-operates with said stopper/piston so as to move it in the syringe body during actuation. The stopper/piston thus needs to guarantee sealing, and it is thus generally made of rubber or some other similar elastomer. A drawback with that type of material relates to the risks of interaction between the material of the stopper/piston and the fluid to be dispensed, in particular during the storage stage, where such interaction might possibly spoil said fluid. In order to limit the risks of interaction, it has been proposed to coat the front surface of the stopper/piston, i.e. the surface in contact with the fluid while storing and while dispensing the fluid, with an appropriate coating. In particular, it has thus been proposed to have a thin film of ethylene tetrafluoroethylene (ETFE) on the front surface of the stopper/piston. This embodiment makes it possible to limit the risks of interaction between the material of the stopper/piston and the fluid, but the presence of the coating on the front surface stiffens said surface, and thus makes it more difficult to assemble and move the stopper/piston in the syringe body. More precisely, the presence of the front coating reduces the capacity of the front surface of the stopper/piston to deform, and thus makes it more difficult to insert it in the syringe body and to slide it therealong. There thus exists a problem of finding a good compromise between sealing that is sufficient for the stopper/piston once inserted in the syringe body, and a process of assembly and of actuation that is not too complicated or difficult.
In addition, co-operation between the stopper/piston and the actuator member, generally a piston rod, generally occurs by means of a screw thread that is provided in the inside surface of the stopper/piston and that co-operates with a corresponding thread that is formed on the leading end of the piston rod. That technique also complicates manufacture of the stopper/piston, in particular the unmolding stage, as a result of the large amount of back-drafts required in the mold for manufacturing the stopper/piston in order to mold the thread.
Documents WO 2006/021380, EP 1 180 377, EP 1 674 121, DE 100 06 560, WO 02/092312 describe prior-art devices.
An object of the present invention is to provide a stopper/piston that does not have the above-mentioned drawbacks.
In particular, an object of the present invention is to provide a stopper/piston that guarantees complete sealing during storage and during actuation, while enabling assembly and actuation to be simplified and reliable.
Another object of the present invention is to provide a stopper/piston that is simpler and thus less costly to manufacture and to assemble, in particular in the process of molding said stopper/piston and while the stopper/piston is being inserted into a syringe body.
The present invention thus provides a stopper/piston, in particular made of elastomer, comprising a cylindrical body having a front axial end that is closed by a front wall, said cylindrical body including an outside surface that is provided with at least one sealing profile, said front wall including a front axial outside surface that is provided with a coating, advantageously a film made of ethylene tetrafluoroethylene (ETFE), said front wall including a sealing profile on its radially-outer edge, said front axial outside surface of said front wall including a deformation profile that is arranged radially inside said sealing profile of said front wall, said deformation profile being adapted to deform radially so as to make it easier to insert and/or to slide said stopper/piston into a syringe body.
Advantageously, said hollow cylindrical body includes a plurality of sealing profiles, advantageously two.
Advantageously, said at least one sealing profile of said hollow cylindrical body is a radially-projecting bead.
Advantageously, said deformation profile is made in the shape of a peripheral groove that is formed in said front axial outside surface of said front wall, said groove advantageously being V-shaped or U-shaped.
Advantageously, said sealing profile of said front wall is formed between said deformation profile and a radially-outer peripheral recess that is axially offset towards the rear relative to said front axial outside surface, said radially-outer peripheral recess also being deformed while said stopper/piston is being inserted into a syringe body and/or while it is being actuated. Advantageously, said cylindrical body is hollow and defines an internal volume, said hollow cylindrical body having an open rear axial end that is axially remote from said front axial end that is closed by said front wall.
Advantageously, said internal volume is adapted to co-operate with an actuator member of a syringe device.
Advantageously, on its inside surface, said hollow cylindrical body includes a screw thread that is adapted to be engaged on a thread of said actuator member.
Advantageously, said thread is discontinuous, a plurality of axial grooves, advantageously four grooves, made in the inside surface of said hollow cylindrical body, being provided so as to interrupt said thread.
Advantageously, said front axial outside surface is conical and defines a central axial tip.
In a variant, said front axial outside surface is substantially plane and perpendicular to a central axis of said stopper/piston.
Advantageously, said deformation profile is of rounded shape, such that said front axial outside surface of said front wall does not have any sharp angle.
The present invention also provides a syringe device including a cylindrical syringe body containing a fluid, said syringe body slidably receiving a stopper/piston as described above.
Advantageously, said at least one sealing profile of said hollow cylindrical body and said sealing profile of said front wall co-operate in leaktight manner with the cylindrical inside surface of said syringe body, said front axial outside surface being in contact with said fluid.
Advantageously, said sealing profile is provided, at least in part, with said coating, thereby defining a cylindrical sealing zone between the cylindrical inside surface of said syringe body and said coated sealing profile.
The present invention also provides a machine for manufacturing a stopper/piston as described above, including a first mold portion and a second mold portion, said first mold portion defining the shape of said hollow cylindrical body, and said second mold portion defining the shape of said front wall.
Advantageously, said first mold portion includes a core comprising a body that is extended by an axial endpiece defining said internal volume, said axial endpiece being provided with an external thread that is separated by a plurality of axial splines, advantageously four splines, defining a thread and axial grooves of said stopper/piston.
These characteristics and advantages and others of the present invention appear more clearly from the following detailed description, given by way of non-limiting example, and with reference to the accompanying drawings, in which:
The outside surface of the hollow cylindrical body 11 includes at least one sealing profile 110, and preferably a plurality of them that are generally made in the shape of radially-projecting beads. Preferably, and as shown in
In the present invention, said front axial outside surface 131 of said front wall 13 includes a deformation profile 133 that is adapted to deform so as to make it easier to insert the stopper/piston 10 into a syringe body 1. The deformation profile is arranged radially inside said sealing profile 130, i.e. it is not arranged at the radially-outer edge of said front wall 13. Advantageously, the deformation profile 133 is made in the shape of a peripheral groove that is formed in said front axial outside surface 131. In the embodiment shown in
Advantageously, said deformation profile 133 is of rounded shape, i.e. it does not define a sharp angle in said front axial outside surface 131 of said front wall 13. This is because such sharp angles might generate zones of weakness in the coating 135, not only while molding the stopper/piston, during which they might generate portions that become torn off, but also in use during which the coating 135 might crack or tear at said sharp angles, e.g. while compressing the stopper/piston when putting it in place in the syringe, with the consequent risk of said coating being discontinuous.
Advantageously, said coating 135 extends not only over said front axial outside surface 131, but also over at least a part of the outside cylindrical surface of said sealing profile 130, as can be seen more clearly in
The presence of the deformation profile 133 in the front axial outside surface 131 of the front wall 13 makes insertion easier. Specifically, the presence of the coating 135 stiffens the material and thus generally makes it more difficult to insert.
Advantageously, as can be seen in
The internal volume 15 of the stopper/piston 10 may include a thread 115. Advantageously, the thread 115 is discontinuous. This embodiment facilitates the process of molding the stopper/piston, as described below. Advantageously, a plurality of axial grooves 116, advantageously four grooves, are provided so as to interrupt said thread 115. With reference to
Naturally, the embodiments in
Naturally, any number of axial splines 216 could be provided. If so desired, the
In known manner, the piston of the invention may also be coated entirely with silicone oil so as to enhance its sliding, in particular while it is being inserted into the syringe. In a variant, when it is desired to omit silicone oil, a parylene coating may alternatively be provided, likewise over the entire piston. In this configuration, the ETFE film on the front surface of the piston could be treated so as to provide grip for the parylene.
Although the present invention is described above with reference to various embodiments, naturally the present invention is not limited by those embodiments, and, on the contrary, any useful modification could be applied thereto by the person skilled in the art, without going beyond the ambit of the present invention, as defined by the accompanying claims.
Number | Date | Country | Kind |
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1359773 | Oct 2013 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FR2014/052540 | 10/7/2014 | WO | 00 |