Activation device for passenger protection apparatus

DETAILED DESCRIPTION The present invention has been developed with a view to eliminating the above-mentioned problems, and it is therefore an object of the invention to provide an activation device for a passenger protection apparatus, capable of detecting a trip-over type roll at an earlier stage for activating the passenger protection apparatus quickly.
For this purpose, in accordance with a first aspect of the present invention, there is provided an activation device for a passenger protection apparatus which is made to activate the passenger protection apparatus in accordance with a behavior of a vehicle, comprising an angular velocity sensor for detecting a roll angular velocity of the vehicle, relative angle calculating means for calculating a roll relative angle of the vehicle on the basis of the roll angular velocity detected by the angular velocity sensor, roll judging means for making a judgment indicating the occurrence of a roll of the vehicle when the roll angular velocity detected by the angular velocity sensor and the vehicle roll relative angle calculated by the relative angle calculating means satisfy a predetermined threshold condition, drive control means for activating the passenger protection apparatus when the roll judging means makes the vehicle roll judgment, a plurality of acceleration sensors for detecting accelerations of the vehicle in its right- and left-hand directions, collision state discriminating means for making a discrimination of a collision state of the vehicle on the basis of the accelerations detected by the plurality of acceleration sensors, and threshold switching means for setting the predetermined threshold condition for the judgment on the vehicle roll in accordance with the collision state discriminated by the collision state discriminating means.
Thus, the plurality of acceleration sensors detect accelerations of the vehicle in its right-hand and left-hand directions, and the collision state discriminating means makes a discrimination of a collision state of the vehicle (that is, the occurrence and non-occurrence of collision, the occurrence and non-occurrence of the deformation of the vehicle, and others) on the basis of the accelerations respectively detected by the plurality of acceleration sensors, and then the threshold switching means sets a predetermined threshold condition for the judgment on a roll of the vehicle in accordance with the collision state discriminated by the collision state discriminating means