Winding-up device with automatic lock for safety belt

Claim 1

In combination with a winding device for a safety belt, a tubular spool formed by rolling up a piece of metal into cylindrical form embossed to have serrated edges thereof defining an axial slot connected to one end of the belt, a return spring biasing the spool in take up direction, a housing having a base and end walls upstanding from the base, the walls having bores of predetermined diameter receiving ends of said spool journaled thereby, and a locking device independently operatively interposed between said spool and said housing operable in response to acceleration of said spool in pay out direction to lock the spool to the housing, said locking device comprising a support disc fixed to one end of said spool outside one end wall of said housing, an inertia disc mounted loosely over said spool between said one end wall and said support disc for rotation in a plane perpendicular to the longitudinal axis of the spool and for sliding movement along the spool, axial cams on said support disc comprising surfaces inclined toward the inertia disc in a direction opposite to the pay out direction of rotation of said spool, said inertia disc being a stamping formed in star configuration and having radial arms adjacent said inclined surfaces which ride up said surfaces when the spool is accelerated in pay out direction, said radial arms each having at least one circumferential side being bent out of the plane of rotation of said inertia disc, first abutment noses on said one wall of said housing to abut one side of said arms when the arms ride up said inclined surfaces, and second abutment noses on said support disc at the upper ends of said inclined surfaces facing said first abutment noses and engageable with the other sides of said arms when the arms ride up said inclined surfaces, said first and second abutment noses being axially offset so as normally freely to pass by one another during rotation of said spool, a bolt extending axially through said spool and arresting the spool axially, said return spring being connected between one end of said bolt and said housing, one end of said bolt fitting closely into said spool relative to one wall of the housing, one end of said belt having a loop thereon which fits over said bolt, said spool being axially slotted to receive said belt, the shank end of said bolt extending to the vicinity of said support disc, said spool being hollow, said support disc having an extension fitting inside said spool, said extension extending into said spool to a location adjacent to the end wall of said housing, a spacer sleeve on said spool between said support disc and said one end wall of said housing, said inertia disc being mounted on said sleeve, and a conical spring between said one end wall and said inertia disc biasing said inertia disc toward said support disc, the axial extent of said inclined surfaces being equal to the axial extent of said radial arms of said inertia disc at the regions which cooperate with said abutment noses plus the axial spacing between said first and second abutment noses.