Sprocket structure of engine

A sprocket structure of an engine, the sprocket structure comprising:

• a crank sprocket provided in a cylinder block of the engine, driven by a crankshaft, the crank sprocket having a crank jig inserted into a center thereof to fix the crankshaft and to allow only an outer portion of the crank sprocket to be rotated;
• a high pressure pump sprocket configured to receive rotational force from the crank sprocket through a timing belt, the high pressure pump sprocket having a high pressure pump jig inserted into a center thereof to fix a shaft of a high pressure pump to allow only an outer portion of the high pressure pump sprocket to be rotated;
• and
• a cam sprocket having an outer sprocket formed on an outer side of the cam sprocket and that is freely rotated by the timing belt and an inner sprocket provided within the outer sprocket and directly connected to a camshaft to fix timing and to apply tension to the timing belt.