Patent ID: 8857854

Claim:
A vehicle occupant restraint system comprising a spindle that winds a seatbelt, an electric actuator that generates motive power for rotating the spindle, a clutch mechanism that connects or disconnects the electric actuator and the spindle, a power transmission mechanism that can transmit motive power from the electric actuator to the clutch mechanism, and collision possibility detector configured to detect information for determining a possibility of collision, and a controller coupled to the electric actuator, wherein the power transmission mechanism further comprises: a first reduction transmission path that reduces the rotation of the electric actuator at a first reduction ratio and transmits the rotation to the clutch mechanism; a second reduction transmission path that reduces the rotation of the electric actuator at a reduction ratio that is higher than the first reduction ratio and transmits the rotation to the clutch mechanism; and switching mechanism configured to switch the connection with the clutch mechanism between the first reduction transmission path and the second reduction transmission path, whereby when a possibility of collision is detected by the collision possibility detector, the controller is configured to supply a driving current to the electric actuator causing winding of the electric actuator in a winding direction, and the rotation of the electric actuator is transmitted to the clutch mechanism at a high speed and low torque via the first reduction transmission path until the coupling of the clutch mechanism is complete and a predetermined time has passed after starting to supply the driving current to the electric motor, and after the coupling of the clutch mechanism is complete and the spindle starts winding the seat belt, the controller is configured to cause the power transmission mechanism to be switched from the first reduction transmission path to the second reduction transmission path, whereby the rotation of the electric actuator is transmitted to the clutch mechanism at a low speed and high torque.