US Patent 7326185 Variable-length needle covering device of an injection device

The invention relates to a needle covering device of an injection device, the injection device including a casing comprising a reservoir, in particular an ampoule, for a product fluid to be administered, and an injection needle for injecting the product fluid from the reservoir, wherein the device surrounds the injection needle in an extended position and exposes the injection needle in a retracted position. The device comprises a passage for the injection needle, a front section via which the device is placed on an injection point, and another section which is nearer to the casing than the front section is, at least in the extended position. The sections can be moved axially relative to the casing and relative to each other, such that the device is variable in its length, the front section being guided in a straight line on the casing.