| 主权项 |
1. A flat plane crankshaft for an in-line four cylinder engine, the crankshaft comprising:
five crank journals; four crank pins; and eight crank arms including:
a second crank arm being a crank arm at a second position counted from one of both shaft ends of the crankshaft;a third crank arm being a crank arm at a third position counted from the shaft end of the crankshaft;a fourth crank arm being a crank arm at a fourth position counted from the shaft end of the crankshaft, the fourth crank arm including a counter weight;a fifth crank arm being a crank arm at a fifth position counted from the shaft end of the crankshaft, the fifth crank arm including a counter weight; anda sixth crank arm being a crank arm at a sixth position counted from the shaft end of the crankshaft,each of the fourth crank arm and the fifth crank arm having a smaller width than a width of the second crank arm,each of the third crank arm and the sixth crank arm having a greater width than the width of the second crank arm,andthe width of each crank arm being a maximum value of a dimension of the crank arm between a central axis of the crank journal and a central axis of the crank pin in a direction orthogonal to a line segment vertically extending through the central axis of the crank journal and the central axis of the crank pin when the crank arm is viewed from the shaft end of the crankshaft. |
