Starting device for air bag

A starting device for an air bag comprising:

• a mass body for detecting a rapid deceleration of a vehicle by inertial movement of said mass body;
• a drive shaft, an end portion of said mass body in a direction of inertial movement thereof contacting a vicinity of one end portion of said drive shaft in a longitudinal direction thereof, said drive shaft being urged by spring means via a contacting member so as to abut said drive shaft and hold said mass body at a predetermined position due to urging force of said spring means, said drive shaft having an engaging member at a portion of said drive shaft in the longitudinal direction thereof, and being provided so as to be rotatable around said engaging member due to the inertial movement of said mass body;
• and
• an ignition pin including a shaft member, a first collar portion having a surface and provided coaxially with said shaft member at a portion of said shaft member in the longitudinal direction thereof, and a second collar portion provided coaxially with said shaft member and provided integrally with said first collar portion, and said second collar portion provided such that a distance between an axial center of said second collar portion and a peripheral surface thereof is smaller than a distance between an axial center of said first collar portion and a peripheral surface thereof, a tip end portion of said engaging member engaging said surface and a relief portion being formed in at least a portion of said peripheral surface of said second collar portion so as to prevent said tip end portion of said engaging member from contacting said second collar portion, and in a normal state of the vehicle, movement of said ignition pin is prevented by engagement of said engaging member and said first collar portion, and when the vehicle rapidly decelerates, engagement of said engaging member and said first collar portion is released by rotation of said drive shaft caused by the inertial movement of said mass body, and due to release of the engagement, said ignition pin moves along a predetermined guide path and actuates a detonator so as to expand an air bag.

A starting device for an air bag comprising:

• a mass body for detecting a rapid deceleration of a vehicle by inertial movement of said mass body;
• a drive shaft, an end portion of said mass body in a direction of inertial movement thereof contacting a vicinity of one end portion of said drive shaft in a longitudinal direction thereof, said drive shaft being urged by spring means via a contacting member so as to abut said drive shaft and hold said mass body at a predetermined position due to urging force of said spring means, said drive shaft having an engaging member at a portion of said drive shaft in the longitudinal direction thereof, and being provided so as to be rotatable around said engaging member due to the inertial movement of said mass body;
• and
• an ignition pin including a shaft member, a disc-shaped first collar portion having a surface and provided coaxially with said shaft member at a portion of said shaft member in the longitudinal direction thereof, and a disc-shaped second collar portion provided coaxially with said shaft member and provided integrally with said first collar portion, and said second collar portion provided so that a distance between an axial center of said second collar portion and a peripheral surface thereof is smaller than a distance between an axial center of said first collar portion and a peripheral surface thereof, a tip end portion of said engaging member engaging said surface and a relief portion being formed at the entire peripheral surface of said second collar portion so as to prevent said tip end portion of said engaging member from contacting said second collar portion, and in a normal state of the vehicle, movement of said ignition pin is prevented by engagement of said engaging member and said first collar portion, and when the vehicle rapidly decelerates, engagement of said engaging member and said first collar portion is released by rotation of said drive shaft caused by the inertial movement of said mass body, and due to release of the engagement, said ignition pin moves along a predetermined guide path and actuates a detonator so as to expand an air bag.