Cover of an airbag module having an area forming an hinge with variable lenght

The device (1) has a frame (2) including a wall, and an upper opening (8) extending to an end of the wall. A cover (4) covering a portion of the upper opening is movable relative to the frame, so as to clear the upper opening and allow deployment of an airbag, where the cover is fixed to the wall by a hinge area (12). The hinge area includes a central hinge (20) connecting a central portion of the cover to the frame, and a lateral hinge (22) connecting a side portion of the cover to the frame, where the length of the lateral hinge is greater than the length of the central hinge.