The valve drive apparatus of the invention comprises an exhaust valve drive mechanism
capable of changing an open/close timing of an exhaust valve, and a control device
which controls the exhaust valve drive apparatus so as to release the exhaust valve
during an intake stroke, independently of an exhaust stroke, in an EGR mode. Preferably,
the exhaust valve drive mechanism comprises a first exhaust cam which defines the
exhaust valve releasing timing and the amount of valve lift in the exhaust stroke,
and a second exhaust cam which defines the exhaust valve releasing timing and the
amount of valve lift during the intake stroke. In an normal mode, the displacement
of the first exhaust cam is transmitted to the exhaust valve, and in the EGR mode,
the displacement of the second exhaust cam is transmitted to the exhaust valve,
in addition to the displacement of the first exhaust cam.
