Patent ID: 6948640

Claim:
A fluid reservoir ( 1 ) having a neck ( 11 ) defining a substantially cylindrical drum ( 12 ) and an opening ( 110 ), said neck being externally provided with an external thread ( 13 ) serving to co-operate with a ring ( 21 ) internally provided with an internal thread ( 210 ) having the same pitch as the external thread ( 13 ) of the neck, the external thread ( 13 ) projecting radially outwardly from the drum and having a crest defining a crest line, the thread being provided with locking means ( 16 ) to prevent the ring from being unscrewed, said locking means comprising at least one projection ( 16 ) situated under the external thread ( 13 ) on a path of the internal thread ( 210 ), and wherein said projection ( 16 ) comprises a ramp ( 161 ) on which the internal thread ( 210 ) engages during tightening, and a locking edge ( 162 ) at the end of the ramp ( 161 ) defining therebeyond a locking wall ( 163 ) against which the internal thread ( 210 ) abuts in the event of unscrewing, and wherein the ramp ( 161 ) slopes gently downwards, the locking edge extending from the drum to the crest line; and wherein the projection projects away and below the external thread.