US Patent 7665437 Oil passage structure of valve operating system

In a cam journal (12A) in which a timing-advance oil passage (12a) and a timing-retard oil passage (12b) are provided as a first oil passage for VVT, an oil passage (102c) for HLA is provided as the second oil passage. The timing-advance oil passage (12a) and the timing-retard oil passage (12b), which are formed on the surface of the intake camshaft (12), are separated from the oil passage (102c) for HLA by a lower cam bearing (202). Thus, it is possible to provide the control oil passages for VVT and the oil supply passage for HLA in one cam journal (12A).