Active control of occupant's body with a limited force restraint system during a frontal impact

摘要

An active control device and a limited force safety belt system are employed to control the motion of a vehicle occupant's body in a head-on collision. The safety belt system comprises a constant-force coil spring mechanism connnected to the fixed point of a three point seat belt at its free end, and to the vehicle frame (6) through a drum and a bearing bracket at the other end. The occupant's body is primarily restrained by the safety belt up to a deceleration value corresponding to human tolerance limits, after which the belt relaxes providing the occupant with a saturated resistance thereby activating the active control device which comprises a double-acting hydraulic cylinder (4) connected between a vehicle seat frame (5) and a vehicle frame (6) upon which the seat frame is slidably mounted for movement in a longitudinal direction relative to the vehicle. The seat frame (5) is releasably fixed to the vehicle frame (6) by a solenoid actuated detent controlled by a microprocessor electrically connected to an accelerometer. A linear variable differential transformer measures the linear position of the seat and a rotary variable differential transformer measures the angular motion of the occupant's body. The transformers transmit signals to the microprocessor which in turn transmits signals responsive thereto to a directional control valve which controls the hydraulic fluid supplied to and exhausted from the double-acting hydraulic cylinder for controlling the forward sliding movement of the seat depending upon the severity of the impact level. This active control device actively dampens the remaining occupant's kinetic motion thus supplementing the safety belt.