1. US20050284977 - Seat belt retractor with electric motor

A retractor for a seat belt of a vehicle has a winding shaft for winding up a seat belt. A motive spring biases the winding shaft in the winding direction of the seat belt. An electric motor produces torque can be transmitted to the motive spring to change the spring force. A switch coupling transmits the torque of the electric motor to the winding shaft to wind up the seat belt. A gear transmits the torque of the electric motor to the winding shaft or the motive spring. The motive spring, the coupling and the gear are provided on one side of the seat belt retractor. The gear comprises a drive wheel which is rotatably mounted on a shaft rotationally and coaxially connected to a winding shaft, and which is rotationally connected to an outer spring end of the motive spring by a rigid rotary connection. A first active surface of the coupling is movably mounted against a restoring force on a component securely connected to the rigid rotary connection and is able to rotate around the shaft. A second active surface of the coupling is rotationally connected to the shaft.