Internal combustion engine

An internal combustion engine provided with a plurality of cylinders, an intake valve and an exhaust valve provided to each of the cylinders, an independent intake passage communicating at a downstream end thereof with each of the cylinders through the respective intake valve, and an independent exhaust passage communicating at an upstream end thereof with each of the cylinders through the respective exhaust valve, the engine comprising:

• an intake camshaft including intake cam lobes configured to reciprocatably move the intake valves to have a given lift characteristic, respectively, and mechanically connected to the intake valves;
• an exhaust camshaft including exhaust cam lobes configured to reciprocatably move the exhaust valves to have a given lift characteristic, respectively, and mechanically connected to the exhaust valves;
• and
• a variable phase mechanism configured to change rotational phases of the intake camshaft and the exhaust camshaft with respect to a crankshaft, respectively, so that a valve overlap during which both of the intake valve and the exhaust valve of the same cylinder are open is made,
• wherein the intake cam lobes are formed such that an open period of each intake valve from an open timing to a close timing is 210° or larger and 330° or smaller of a crank angle, and
• wherein the exhaust cam lobes are formed such that, for each cylinder, during the overlap period when the variable phase mechanism advances the rotational phase of the intake camshaft to the maximum, and retards the rotational phase of the exhaust camshaft to the maximum, an amount of effective valve lift (Lift(CA)) of the exhaust valve, an inner circumferential length (L_ex) of a valve seat that contacts the exhaust valve when the exhaust valve is closed, and a swept volume (V) per cylinder satisfy the following formula, the amount of effective valve lift being a function of a crank angle from the open timing (CAIVO) of the intake valve to a middle timing (CAcenter) of the overlap period:
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