Patent ID: 7941192

Claim:
A torsion coil spring having stretching force in a torsional direction, comprising: a first coil part and a second coil part; and a first straight line part, a second straight line part, and a third straight line part, wherein: one end of the first coil part continues to one end of the first straight line part, while the other end continues to one end of the second straight line part; the other end of the second straight line part continues to one end of the second coil part; and the other end of the second coil part continues to one end of the third straight line part, and wherein the first coil part and the second coil part are wound in mutually opposite directions with gradually diminishing radiuses from ends of the second straight line part, and maximum radius segments and minimum radius segments of the first coil part and the second coil part are arranged on a same plane as the second straight line part, the minimum radius segment of the first coil part and the minimum radius segment of the second coil part protrude in the same direction away from the same plane and are continuous respectively to the first straight line part and the third straight line part.