| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem of often insufficiently exhibiting a spring performance because of contact and catching of opposed plate surfaces to each other when being wound. SOLUTION: This spiral spring 430 is so formed that a steel plate surface having a sufficiently high rigidity is formed with a pair of projections 431 and 431 at a prescribed interval apart in the width direction in opposite positions to the opposite plate surface. If the opposite plate surfaces are contacted with each other when a seat back is reclined rearward and the spiral spring 430 are wound, the opposite surfaces are contacted with each other only on points, or the adjacency of the vertices of the projections 431 and 431. This constitution reduces the contact area so as to smoothly wind the spiral spring and sufficiently exhibit the spring performance. |
