Adaptive load-limiting seatbelt assembly

An adaptive load-limiting seatbelt assembly for restraining an occupant of a passenger vehicle during a dynamic event, the assembly comprising:

• a frame, a spool drum rotatably mounted to the frame for rotation about an axis, and a piezoelectric device, the spool drum carrying a length of seatbelt webbing that pays out from the spool drum for securing an occupant of the vehicle;
• the piezoelectric device comprising a first member, a second member, and a control system, the first member being formed of a piezoelectric material;
• one member of the first member and the second member being rotatably mounted with respect to the frame and the other of the first member and the second member being fixedly connected to the frame, the one member being non-rotatably connected to the spool drum by one or more mechanical non-rotatable connections whereby rotation of the spool drum urges rotation of the one member around a member axis and enables torque to be continuously transmitted through the one or more mechanical non-rotatable connections between the one member and the spool drum;
• the first and second members comprising facing bearing surfaces being concentric with the member axis and being movable with respect to one another with rotation of the one member;
• the first member being responsive to changes in applied voltage to the first member to define a variable interference fit between the two facing surfaces that generates a variable frictional force resisting relative motion of the two surfaces with respect to one another;
• the control system comprising a controller, at least one sensor being configured and disposed to transmit a data signal to the controller representing the speed of pay-out and/or the amount of pay-out of seatbelt webbing from the spool drum, and a variable voltage source, the voltage source electrically connected to the first member;
• The controller being configured to control rate of pay-out of the spool drum during the dynamic event by controlling the voltage applied to the first member by the variable voltage source in response to the data signal being received by the controller and thereby control the interference fit between the first and second members to control the rate of rotation of the spool drum during the dynamic event.