Patent ID: 6964249

Claim:
A valve timing control system for an internal combustion engine, comprising: a housing comprising a main body having a peripheral wall and a sidewall member having a bearing hole supporting a shank of a member on the side of a camshaft and closing a side of the main body; an advance chamber arranged in the housing, the advance chamber being supplied with a working fluid to cause a relative rotation of the camshaft in the advance direction with respect to a crankshaft; a retard chamber arranged in the housing, the retard chamber being supplied with the working fluid to cause the relative rotation of the camshaft in the retard direction with respect to the crankshaft; a hydraulic-pressure supply/discharge device which selectively supplies and discharges the working fluid to and from the advance chamber and the retard chamber, the hydraulic-pressure supply/discharge device comprising two supply/discharge passages; an annular recess formed in the sidewall member of the housing to face the housing main body, the annular recess communicating with one of the supply/discharge passages of the hydraulic-pressure supply/discharge device; and a radial groove formed to radially extend from the annular recess, the radial groove communicating with one of the advance chamber and the retard chamber.