FIELD OF THE INVENTION

The present invention relates to an injection device and a syringe provided with such a device.

A preferred application is in the medical devices and accessories industry.

TECHNOLOGICAL BACKGROUND

In the medical field, injection devices using a needle are known, this term referring here to any pointed device allowing a fluid to pass therethrough towards the human or animal body in particular. In particular, such a device as a syringe comprising a body and a piston that can slide in the body is known from document WO 2004/014470 A1. In addition, to carry out the injection, the syringe includes an injection device attached to the head of the syringe body and provided with a needle. Such a device is illustrated inFIGS. 1 to 3. The device attached to the head of the syringe body comprises a part enabling it to be mounted on said body, as a mechanical interface and a part whereon the needle is assembled forming the casing receiving this needle. The casing and the interface are in contact. Nevertheless, according to this anteriority, the needle is retractable into the syringe body once the injection operations are completed. This provision provides greater safety of use to the medical device. To achieve this retraction, the casing carrying the needle is disconnected from the interface as shown inFIG. 2. The fact that the casing and the interface must move from a position where they are secured together and sealed to a position where they are disconnected raises sealing issues that are generally solved by separately applied O-rings.

The sealing techniques thus used seriously increase the complexity of the assembly of the devices and their costs.

A needle deflection system is known from US document U.S. Pat. No. 4,804,370 A1 in which the root of the needle, visible in FIG. 5, forms the deflection surface. The needle base is received in a symmetrical elastomer cavity.

US document A1 2008/027381 shows a single cooperation area (see FIG. 14) between a needle-bearing casing and a housing secured to the syringe piston. US document A1 2006/253074 discloses a cooperation equivalent to the previous publication between the piston and the casing.

Document WO A1 91/07198 shows a single, continuous tab in a plane transverse to the length of the syringe and provided with a stop capable of cooperating with a piston housing.

Document WO A2 2007/123826 also shows a cooperation between a single casing surface and a single surface of a piston housing.

The present invention makes it possible to remedy all or at least some of the drawbacks of the current techniques.

SUMMARY OF THE INVENTION

One aspect of the invention relates to a syringe provided with a body, a piston capable of sliding in the body, and an injection device comprising a needle oriented along a longitudinal axis and a casing removably secured to the body and carrying said needle, the casing comprising a plurality of flexible tabs each provided with a stop, the piston comprising a docking system provided with a housing that comprises a flange configured to hold the stops of the flexible tabs in the housing in an insertion position in which the tabs are inserted into the housing, the plurality of tabs comprising a first tab and a second tab situated in opposing areas around the longitudinal axis, the flange comprising a first bearing area and a second bearing area configured to be in contact respectively with the first tab and the second tab in the insertion position.

Advantageously, the first tab and the second tab are configured to exert an elastic pressure respectively on the first bearing area and the second bearing area in the insertion position, and the first bearing area and the second bearing area are dissymmetrical relative to the longitudinal axis.

Thus, the contact on the two bearing areas cannot be symmetrical around the longitudinal axis, the bearing forces are therefore not balanced, and this causes the casing and therefore the needle to tilt, so that the latter is permanently enclosed in the syringe body. The tilting is carried out efficiently without significant effort from the user because there is little resistance to the insertion sufficient to cause tilting. Advantageously but not restrictively, the tabs have a free distal end, and not joined together as is necessary in the case of a cavity bottom used for tilting the casing, so their flexibility can be chosen high.

It should be noted that there are several flexible tabs, which enables distinct elastic bearings to be provided on several places in the housing.

