Patent ID: 7104601

Claim:
A vehicle occupant restraint system for restraining a lower part of a vehicle occupant, comprising: a restraining member supported by a seat frame so as to be moveable between a retracted position leaving a seat bottom in an undisturbed state and a deployed position for restraining a lower part of a vehicle occupant by projecting a part of said seat bottom upward from a normal surface of said seat bottom, wherein said restraining member comprises a laterally extending member located under said seat bottom at a substantially longitudinally middle point of said seat bottom, and a pair of arms pivotally supporting said laterally extending member with respect to said seat frame; a crash sensor for detecting an occurrence of a vehicle crash; a crash prediction sensor that provides data for predicting an occurrence of a vehicle crash; a power actuator including a cylinder fixedly supported by said seat frame and having an open end and a closed end, a gas generator received in said closed end of said cylinder, a piston received in said cylinder, a piston rod having one end engaging said piston and another end projecting out of said open end of said cylinder, said piston rod including a threaded section and supported so as to be rotatable around an axial line thereof, a nut member threadably engaging said threaded section of said piston rod and supported by said seat frame against a reaction force of said piston rod axially moving into said cylinder and an electric motor adapted to turn said piston rod around said axial line thereof, wherein said cylinder is provided on a side part of said seat frame and extends in a fore-and-aft direction and said piston rod is rotatably supported by a moveable member which is guided by said seat frame so as to be moveable in a fore-and-aft direction, said arms being pivotally supported by said moveable member and being provided with an arcuate slot receiving a pin fixedly attached to said seat frame so as to effect a pivotal upward movement of said arms by a forward travel of said moveable member; a power transmitting mechanism for converting an axial movement of said piston rod into a movement of said restraining member toward said deployed position; and a control unit for activating said electric motor to cause said restraining member to a partly deployed position upon prediction of an occurrence of a vehicle crash according to said data from said crash prediction sensor, said control unit returning said restraining member from said partly deployed position back to said retracted position upon failure to detect an actual crash by said crash sensor, and fully deploying said restraining member from said partly deployed position upon detection of an actual crash by said crash sensor.