Shock-proof device in buckle, buckle having the shock-proof device, and seat belt apparatus having the buckle

摘要

In order to provide a shock-proof device capable of preventing disengagement between a tongue and a buckle due to an inertial force regardless of a direction of the inertial force, a release button (8) is provided with a button-side first engagement connection part (8d) composed of a vertical plane and a button-side second engagement connection part (8e) composed of an inclined plane. When an inertial force of the release button (8) in a release direction is applied to the release button (8) and an inertia lever (9), a lever-side engagement connection part (9c) abuts the vertical plane of the button-side first engagement connection part (8d). At this time, a torque applied to the inertia lever (9) due to an inertial force of the release button (8) is comparatively large. When an inertial force of the release button (8) in a non-release direction is applied to the release button (8) and the inertia lever (9), the lever-side engagement connection part (9c) abuts the inclined plane of the button-side second engagement connection part (8e). At this time, a torque applied to the inertia lever (9) due to an inertial force of the release button (8) is comparatively small. By generating a torque difference according to the direction of the inertial force in such a manner, the engagement between a buckle and a tongue is securely maintained.