Seat belt pretensioner

Abstract

In the seat belt pretensioner device according to the present invention, because the buckle is pulled by urging an intermediate point of the cable, it is possible to pull the seat belt and buckle by a required stroke with a relatively small stroke of the power actuator, and this contributes to a compact design of the device. Because the buckle can be pulled via a fixed point of a cable guide, the buckle and, hence, seat belt can be pulled in a stable manner, and a high level of reliability can be achieved. For instance when the power actuator comprises a piston rod that is pushed out by high pressure gas, because a high pressure gas can be produced with a relatively small device, the size and weight of the device can be minimized. By using a cushioning strucgture for gradually absorbing kinetic energy toward the terminal end of the motion of the power actuator, an inadvertent unlatching of the buckle owing to an impulsive movement of the buckle can be avoided, and an excessive reaction force is prevented from being transmitted to the pretensioner device. This reduces the need for a high mechanical strength, and contributes to compact design. Also, impulsive noises at the terminal end of the operation of the device can be minimized and the device can operate in a quite manner.