Impact energy absorbing device for motor vehicle door

Device for absorbing impact energy for a door of a motor vehicle, the door (1) being in the form of a roughly parallelepipedal hollow box (2) which has an upper face (9) and a lower face (8) and in which is arranged a glass panel (12) capable of sliding substantially vertically between a lowered position in which it is substantially retracted into the box (2) and a raised position in which it is substantially deployed through the opening (14) of the upper face (9), the absorbing device (30) being arranged in a lower region of the box (2) and comprising two shock-absorbing blocks (32, 33) defining a passageway for the glass panel (12) therebetween, characterized in that it comprises movable members (39) for mechanical connection between the shock-absorbing blocks (32, 33), each of those members (39) being arranged in the passageway for the glass panel (12) in order to assume an active position, in the absence of the glass panel (12), in which it ensures mechanical continuity between the blocks (32, 33) and constitutes a supplementary component for absorbing impact energy, and in order to move out of the way to assume an inactive position when the glass panel (12) passes through.