Valve opening-closing timing control device

A valve opening-closing timing control device comprising:

• a driving-side rotor that rotates around a rotation axis synchronously with a crankshaft of an internal combustion engine;
• a driven-side rotor that is arranged on an inner side of the driving-side rotor coaxially with the rotation axis and rotates integrally with a camshaft for opening and closing a valve of the internal combustion engine;
• and
• a phase adjustment mechanism that adjusts a relative rotational phase between the driving-side rotor and the driven-side rotor, wherein
• the phase adjustment mechanism includes:
• an internal-teeth output gear that rotates integrally with the driven-side rotor around the rotation axis as a common axis;
• an external-teeth input gear that has a smaller number of teeth than the output gear, is arranged on an inner side of the output gear, and rotates around an eccentric axis oriented in parallel to the rotation axis;
• a coupling member that links the input gear to rotation of the driving-side rotor;
• an eccentric member that meshes an external teeth portion of the input gear with an internal teeth portion of the output gear;
• and an electric actuator that drives the eccentric member to rotate around the rotation axis,
• a concave portion is formed on the eccentric member, and is concave from an outer surface of the eccentric member inward in a radial direction in such a way as to allow a spring member to be arranged in the concave portion, and the spring member applies biasing force of meshing the external teeth portion of the input gear with the internal teeth portion of the output gear 25, and
• the concave portion includes a spring support surface that receives biasing force of the spring member, the spring support surface includes a top surface, and, when viewed in a direction along the eccentric axis, the top surface has a smaller protrusion amount at a circumferential-direction central position of the spring support surface, as compared to an eccentric arc surface whose center is the eccentric axis.