Valve opening and closing timing control apparatus

A valve opening and closing timing control apparatus comprising:

• a driving side rotator configured to rotate synchronously with a crankshaft of an internal combustion engine;
• a driven side rotator disposed coaxially with a rotation axis of the driving side rotator and configured to rotate integrally with a valve opening and closing camshaft;
• a phase controller configured to control a relative rotation phase between the driving side rotator and the driven side rotator by supply and discharge of a fluid;
• and
• a torsion spring configured to attain a biasing force to displace the relative rotation phase between the driving side rotator and the driven side rotator in a predetermined direction,
• wherein the driving side rotator is fastened to a cover-shaped plate, which accommodates the driven side rotator therein and covers the driven side rotator, via a fastening bolt, and a screwing structure that is screwed to the fastening bolt or a head portion of the fastening bolt is formed as a first hook portion that protrudes from the cover-shaped plate,
• the torsion spring includes a first arm provided on one end side thereof so as to be locked by the first hook portion and a second arm provided on a remaining end side thereof so as to be locked by a second hook portion of a locking member that rotates integrally with the camshaft, and
• when a height of the first hook portion from a surface of the cover-shaped plate is assumed to a locking height H, a height of the second hook portion from the surface of the cover-shaped plate at a locking position is assumed to a reference height a, a distance between opposite end positions of a spring material in a close contact state of the torsion spring is assumed to a close contact length b, and a thickness of the spring material of the torsion spring in a direction along the rotation axis is assumed to a spring material thickness e, a lower limit value of the locking height H of the first hook portion is set based on an equation of H≥a−b+(e/2).