Abstract: The invention relates to a protective assembly used in the field of motor vehicle safety to protect an occupant of a motor vehicle in the event of a collision. The protective assembly comprises a module itself containing a gas generator, an external deflector and an air bag initially folded around the generator, characterized in that: i) the generator comprises a body of tubular overall shape which has a side wall bearing discharge orifices distributed around the circumference of the side wall, the latter having a circular cross section, the outside perimeter of which has a length L, ii) the external deflector can expand and is made using a metal strip which is 2L long, iii) the discharge orifices are initially covered by the expanding external deflector which closely surrounds the side wall.