Cover for air bag installation

Claim 1

In an air bag assembly for use in a motor vehicle including a rigid box shaped housing having a bottom and a side wall defining a substantially open top, a collapsed air bag within said housing, an inflator connected to inflate said air bag, and a cover closing said housing and defining tear lines adapted to be ruptured by the inflating air bag, the improvement which comprises: said cover being of a substantially homogeneous material; said tearlines being thin regions of the cover material forming a generally H-shaped pattern having at least three portions of differing thickness wherein the first and thinnest tear line portions are the crossbar of the H and the regions of the vertical bars immediately adjacent the crossbar, the succeeding, second portions of the vertical bars being thicker, with the end of each vertical bar terminating in a third portion defining a curve leading to a thickened hinge region of the cover, the third portion having a thickness intermediate that of the first and second portions; an outwardly extending rim on said side wall disposed around at least a portion of said open top; a plurality of locking arms integral with said cover and engaging said rim; and means secured to the bottom of said housing for retaining at least two of said locking arms in engagement with said rim during inflation of said air bag, whereby the thinnest tear line portions will be the first to rupture and form doors releasing said air bag and energy from the expanding air bag will be absorbed during the formation of said doors.