Air inlet shut-off device for a motor vehicle, with an automatic return system

An air inlet shut-off device for a motor vehicle, the shut-off device comprising a support frame including a first and a second crosspiece that are parallel to one another and connected by lateral uprights so as to define at least one passage opening for an incoming air flow, said device including at least one curtain that can move between a closed position in which the at least one curtain at least partially covers the at least one passage opening and an open position in which said at least one curtain allows the incoming air flow to pass through the at least one passage opening, said at least one curtain including an edge secured to a first roller shaft extending on the support frame along one of the sides of the at least one passage opening, the first roller shaft being connected to a drive device so as to roll up the at least one curtain around said first roller shaft to bring it into the open position and so as to unroll the at least one curtain to bring it into the closed position, and an automatic return system for the at least one curtain which includes:

• an elastic element which is elastic in elongation along the rolling axis of the first roller shaft, said elastic element being secured with a first end to the first roller shaft in such a way as to be rotated by said first roller shaft and vice versa,
• a cylindrical slider intended to move in translation along the rolling axis of the first roller shaft and in rotation about the rolling axis, said cylindrical slider being secured to a second end of the elastic element in such a way as to be rotated indirectly by the first roller shaft and vice versa, said cylindrical slider also including a helical groove on the outer surface, the support frame including a fixed finger configured to be inserted in the helical groove on the cylindrical slider.