| 摘要 |
PURPOSE:To shorten the longitudinal length of a vehicle body and to make it possible to reduce vibration, by setting the included angle theta of V-type cylinders below 90 deg. so that the relative angle of crank pins is set to pi-2theta. CONSTITUTION:An engine 3 in which cylinders 6 having a crank shaft 5 transversely arranged, take a V-shape having an included angle theta below 90 deg. such as, for example, 70 deg. in the longitudinal direction, is installed on a motorcycle, and one of crank pins, 13b is set to an angle of pi-2theta with respect to the other crank pin 13a in the direction opposite to the direction of the cylinder included angle. Thus, by setting the included angle to 70 deg. less than 90 deg., the longitudinal length of the engine 3 may be shortened, and thereby, the wheelbase may be reduced. Further, since the relative angle of the crank pins 13a, 13b is set to pi-2theta=40 deg., and the first order factor in residual unbalance inertia force of reciprocating masses such as, for example, pistons 10a, 10b may be neglected, vibration in the engine 3 may be decreased. |
