Variable valve drive mechanism and intake air amount control apparatus of internal combustion engine

An intake air amount control apparatus of an internal combustion engine, comprising a variable valve drive mechanism capable of varying a valve characteristic of an intake valve or an exhaust valve of the internal combustion engine, the variable valve drive mechanism comprising:

• (a) a camshaft that is operatively connected with a crankshaft of the engine such that the camshaft is rotated by the crankshaft;
• (b) a rotating cam provided on the camshaft;
• (c) an intermediate drive mechanism disposed between the camshaft and the valve and supported rockably on a shaft that is different from the camshaft, the intermediate drive mechanism including an input portion operable to be driven by the rotating cam of the camshaft, and an output portion operable to drive the valve when the input portion is driven by the rotating cam;
• and
• (d) an intermediate phase-difference varying device positioned and configured to vary a relative phase difference between the input portion and the output portion of the intermediate drive mechanism;
• wherein the intermediate phase-difference varying device is driven so as to change a relative phase difference between the input and output portions of the intermediate drive mechanism, depending upon an intake air amount that is required for the internal combustion engine.