First-order balancer of internal combustion engine

A first order balancer of an internal combustion engine including a crank shaft having first and second ends comprising:

• first and second forward rotating flywheels respectively fitted on said first and second ends of said crank shaft and allowed to rotate in the same direction as said crank shaft;
• first and second backward rotating flywheels respectively disposed outside of each of said first and second ends of said crank shaft and coaxially therewith;
• first bevel gear mechanism disposed at said first end of said crank shaft between said first forward rotating flywheel and said first backward rotating flywheel, and second bevel gear mechanism disposed at said second end of said shaft between said second forward rotating flywheel and said second backward rotating flywheel, said first and second bevel gear mechanisms adapted to rotate said backward rotating flywheels in a direction opposite from a direction of said forward rotating flywheels;
• first and second forward rotational counterweights disposed respectively on said first and second forward rotating flywheels;
• and
• first and second backward rotational counterweights respectively disposed on said first and second backward rotating flywheels said backward rotation counterweights having a different weight from said forward rotational counterweights.