Acceleration sensor

摘要

An acceleration sensor. An inertial mass moves inertially when a vehicle suddenly accelerates. A longitudinal direction portion of a trigger lever abuts a portion of a peripheral surface of the inertial mass at a side in a direction of inertial movement thereof. The trigger lever is pushed by the peripheral surface due to inertial movement of the inertial mass, and is rotated around a fulcrum from a first position to a second position. The trigger lever is provided with a trigger means which is located at a position separated by a predetermined distance from the fulcrum and at a position which is different from a position at which the trigger lever abuts the inertial mass. An ignition pin is movable from a non-actuating position at which an occupant protection device is not actuated to an actuating position at which the ignition pin actuates the occupant protection device. The ignition pin has an engaging member. When the trigger lever is at the first position, the engaging member engages with the trigger means so as to position the ignition pin at the non-actuating position. When the trigger lever is moved to the second position, the engaging member cancels engagement of the trigger means and the engaging member so that the ignition pin is movable to the actuating position. An urging means usually urges the ignition pin toward the actuating position.