Energy absorbing seat belt retractor having a torsion bar
First Claim
1. An energy absorbing seat belt retractor (20) comprising:
- a spool (30) and a torsion bar (50), the torsion bar including first and second end formations (52b and 52a), the first one of the end formations (52b) is drivingly connected to the spool;
the torsion bar further includes a ductile, elongated body (52), located between the end formations, the bar having its grain structure in the vicinity of a center of the bar (50) aligned in a longitudinal direction.
15 Assignments
0 Petitions
Accused Products
Abstract
A torsion bar (50) and seat belt retractor (20). The torsion bar (50) has a circular cross section where the torsion bar is formed as a cold headed extruded part and wherein the grain structure of the metal is aligned along the axis (axial direction) of the bar generally in the center of the bar and the grain structure smoothly diverges from the axial direction near an end formation (52a,b). The torsion bar is later annealed and twisted about 180 degrees.
The seat belt retractor (20) includes: a frame (22) to rotationally support the torsion bar and spool (30). The torsion bar (30) is characterized by an elastic deformation zone and a sharp onset into a plastic deformation zone. The spool is operatively connected to rotate with the torsion bar. The retractor also includes a locking device, activated during a vehicle accident and operatively linked to the torsion bar for preventing one side of the torsion bar from rotating while permitting the other side and the spool to rotate once loaded by the occupant.
18 Citations
7 Claims
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1. An energy absorbing seat belt retractor (20) comprising:
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a spool (30) and a torsion bar (50), the torsion bar including first and second end formations (52b and 52a), the first one of the end formations (52b) is drivingly connected to the spool;
the torsion bar further includes a ductile, elongated body (52), located between the end formations, the bar having its grain structure in the vicinity of a center of the bar (50) aligned in a longitudinal direction. - View Dependent Claims (2, 3, 4, 5, 7)
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6. A method of forming a torsion bar (50) comprising the steps of:
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a) aligning the grain structure on a metal bar, of predetermined diameter, in an axial direction;
b) forming on one end of the bar a first driving formation, c) forming on the other end of the bar a second driving formation.
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Specification