| 摘要 |
PURPOSE:To restrain vibration caused by primary inertia force, by arranging cylinder blocks respectively formed with two and one cylinders, in the horizontal and vertical directions, respectively, at a bank angle of 90 deg., and by providing specific balance weights to a crank shaft. CONSTITUTION:Three pistons 131 through 133 are coupled, respectively through connecting rods 141 through 143 to crank pins 51 through 53 coaxially arranged on a crank shaft 1. Further, cylinder blocks 161, 162 respectively receiving the pistons 131, 132 are arranged in the substantial horizontal direction, and a cylinder block receiving the piston 133 is arranged between the blocks 161, 162 in the substantial vertical direction so that the block 163 is set at a bank angle of 90 deg. with respect to the blocks 161, 162. The total reciprocating mass-weight of first and second piston systems including pistons 51, 52 is made substantially equal to the reciprocating mass-weight of a third piston system including the piston 53, and as well, balance-weights 231 through 233, 23'1 through 23'3 which substantially balance with the inertia force of the first and second piston systems and that of the third piston system, respectively, are arranged to the crank shaft 1. |
