Coupling for Injection Devices

[0008]It is an object of the present invention to provide an irreversible mechanical locking that does not introduce slack between the parts locked together.

[0009]A bayonet coupling as the one known e.g. from WO 99 / 16487 has the advantage that the two elements is pressed together when the two parts are rotated relatively due to the angle of the protrusion and the bayonet thread.

[0010]Combining such bayonet coupling with an irreversible mechanical lock locking the parts together makes the solution very attractive to prefilled injection devices due to the fact that the press fitting of the two elements can reduce the slack occurring due to the injection moulding process involved in producing the various parts. The mechanical lock can be formed such that it locks into its locking position when the two elements are sufficiently pressed together by the bayonet coupling. In this way the mechanical slack can be reduced or even avoided.

[0011]The bayonet coupling is provided with a click-lock