| 摘要 |
PROBLEM TO BE SOLVED: To change a belt web drawing force characteristic to a desired shape over the length of a drawn belt without any complex external control mechanism required for a switch operation, by supporting at least part of the inner diameter of a first torsion bar on a second torsion bar in a state that the first torsion bar is at least twisted. SOLUTION: This unit is constituted with a first hollow torsion bar 10 and a second torsion bar 12 placed in it. The torsion bars 10, 12 are fixingly interconnected through welding portions 14 at both ends in axial line direction. This is combined into a belt retractor by fixing and connecting its one end with a belt reel and the other end with locking teeth. Generated characteristic contains three different force levels; a first high force level determined by the torsion bars 10, 12 connected in parallel, and second and third low force levels determined by the first torsion bars 10 in a non-deformation state and a deformation state. |
