Patent ID: 7686340

Claim:
An occupant restraint system comprising: a seat belt configured to restrain an occupant in a seat of a vehicle; a rollover prediction unit configured to predict a rollover of the vehicle based on a state of the vehicle; a rollover detection unit configured to detect a rollover of the vehicle based on the state of the vehicle; primary and secondary pre-tensioner units configured to apply a tension to the seat belt so as to restrain the occupant in the seat, an operation force of the secondary pre-tensioner unit being stronger than an operation force of the primary pre-tensioner unit; a control unit configured to activate the primary pre-tensioner unit based on a prediction by the rollover prediction unit that a rollover occurs and activate the secondary pre-tensioner unit based on a detection by the rollover detection unit that the rollover occurs; another seat belt configured to restrain another occupant seated in another seat of the vehicle; and tertiary and quaternary pre-tensioner units configured to apply a tension to said another seat belt so as to restrain said another occupant, wherein said rollover prediction unit and/or said rollover detection unit comprise at least one of a steering angle sensor configured to detect an angle of a steering wheel and a brake sensor configured to detect a brake force, wherein the control unit is configured to activate the tertiary pre-tensioner unit based on a rollover prediction signal and activate the quaternary pre-tensioner unit based on the rollover detection signal, wherein an operation force of the quaternary pre-tensioner unit is stronger than an operation force of the tertiary pre-tensioner unit, and wherein an activation timing of the quaternary pre-tensioner unit differs from an activation timing of the secondary pre-tensioner unit.