Odd-cylinder v-type internal combustion engine

An odd-cylinder V-type internal combustion engine comprising:

• 2n+1 cylinders (n is a natural number) arranged in two banks formed in a V-shape, pistons fitted in cylinder bores of the cylinders, connecting rods connected to the pistons, and a crankshaft provided with n common crankpins each connected to the connecting rods connected to two paired ones of the pistons respectively belonging to the two banks, and one odd crankpin connected to the connecting rod connected to the one unpaired piston;
• wherein the n common crankpins are disposed at the same phase,
• a bank angle θ between the two banks meets:
• θ=cos−1(½n),
• the odd crankpin is disposed (180−θ)° behind the common crankpins with respect to a rotating direction of the crankshaft when the unpaired piston belongs to the front bank with respect to the rotating direction of the crankshaft or (180−θ)° ahead of the common crankpins with respect to the rotating direction of the crankshaft when the unpaired piston belongs to the rear bank with respect to the rotating direction of the crankshaft, and
• reciprocating parts including the pistons, associated with all the cylinders, respectively, have the same mass, and the crankshaft is provided with balance weight which generates a balancing force of kMrω2 acting in a sense of (α+180)°, where:
• k = ( 1 2 ⁢ 1 - 1 4 ⁢ n 2 ) 2 + ( n - 1 4 ⁢ n ) 2 α = sin - 1 ( 1 2 ⁢ 1 - 1 4 ⁢ n 2 k )
• α:
• Angle from the common crankpins in the rotating direction
• M:
• Mass of each reciprocating part
• r:
• Crank throw and
• ω:
• Angular velocity of the crankshaft.