A torsion coil spring that generates biasing force which causes a first member and a second member to rotate relative to each other, the first member and the second member being coupled to each other in a rotatable manner, the torsion coil spring comprising:
- a coil portion formed of a wire member wound into a helical shape;
- a first arm portion extending from a first end portion of the coil portion;
- and
- a second arm portion extending from a second end portion of the coil portion,
- the first arm portion including:
- an insertion portion that is inserted into a hole provided in the first member,
- a first intermediate portion that connects the first end portion and the insertion portion to each other, and
- a first bent portion that is bent between the insertion portion and the first intermediate portion,
- the second arm portion including:
- an engaging portion that is engaged with a step portion provided in the second member,
- a second intermediate portion that connects the second end portion and the engaging portion to each other, and
- a second bent portion that is bent between the second intermediate portion and the engaging portion,
- a coil hole at a center of the coil portion having a circular shape as viewed in a center-line direction that is parallel to a center line of the helical shape,
- the first end portion being located behind the center line as viewed in a first direction that is perpendicular to the center line,
- the second end portion being located behind the center line as viewed in a second direction that is perpendicular to the center line,
- the first intermediate portion
- extending, as viewed in the center-line direction, along a first tangent line that is tangent to the circular shape of the coil hole,
- being tangent, as viewed in the first direction, to a first perpendicular line that is perpendicular to the center line, and
- extending, as viewed in the first direction, in a direction that is away from the center line as a distance from the first end portion increases,
- the insertion portion
- extending, as viewed in the center-line direction, in a direction
- that is away from the first tangent line as a distance from the first bent portion increases, and
- that is toward a side opposite to a side where the coil hole is located relative to the first tangent line, and
- extending, as viewed in the first direction, in a direction
- that is away from the first perpendicular line as the distance from the first bent portion increases, and
- that is toward a side where the coil portion is located relative to the first perpendicular line,
- the second intermediate portion
- extending, as viewed in the center-line direction, along a second tangent line that is tangent to the circular shape of the coil hole,
- being tangent, as viewed in the second direction, to a second perpendicular line that is perpendicular to the center line, and
- extending, as viewed in the second direction, in a direction that is away from the center line as a distance from the second end portion increases,
- the engaging portion extending, as viewed in the second direction, parallel to the center line and in a direction
- that is away from the second perpendicular line as a distance from the second bent portion increases, and
- that is toward a side where the coil portion is located relative to the second perpendicular line.