Valve timing changing apparatus for internal combustion engine

摘要

A valve timing changing device for changing valve timings of intake and exhaust valves inhibits a deterioration in precision of a change of a valve overlap period. A first variable valve timing mechanism (first VVT)(13) is mounted to an intake cam shaft (11), and a second variable valve timing mechanism (second VVT)(14) is mounted to a crank shaft (15). A timing belt (37) drivingly couples a cam pulley (38) mounted to an exhaust cam shaft (12), a cam pulley (31) of the first VVT (13), and a cam pulley (39) of the second VVT (14) to one another. The first VVT (13) changes a rotational phase of the intake cam shaft (11) so as to change a valve timing of intake valves (23). The second VVT (14) changes rotational phases of both the intake and exhaust cam shafts (11, 12) so as to simultaneously change valve timings of the intake and exhaust valves (23, 24). <IMAGE>