CONTROLLED FORCE SHOULDER BELT SYSTEM

摘要

A sea belt retractor (5) is provided with an energy management system (10) that achieves a known, predictable dissipation of energy which allows the force load on the shoulder belt (12) and an amount of belt (12) protraction to be carefully controlled for a given vehicle's crash characteristics. The energy dissipation may be tailored to a particular vehicle to provide the desired shoulder belt (12) force loads during a short time interval, such as needed to deploy the air bag. The energy management system (10) will effectively decrease substantially maximum shoulder loads, maximum G's and chest deflection by allowing the belt (5) to protract over a predetermined distance, such as twenty inches. Herein, the inertia dissipation assembly (10) is small and mounted internally of the retractor reel (22) between the reel (22) and its supporting shaft (20). At shoulder belt (12) loads below the onset force level, the inertia or web-sensitive locks (24) lock both the reel (22) and reel shaft (20) against rotation and belt (12) protraction with no energy dissipation. At shoulder belt (12) loads above the onset force level, the reel (22) rotates relative to the locked shaft (20) and moves an extrusion die (36) and a bushing (38) on the reel shaft (20) relative to one another and deforms the wall of the bushing (38) thereby dissipating energy. The extrusion die (36) can be formed integrally on the reel shaft (20) with the driver nut (34) pushing the bushing (38) axially onto the die (36) section of the shaft (20) to deform the bushing (38). The energy dissipation is consistent and predictable and done without a substantial increase in size of the seat belt system (5) and at a modest additional cost.