Crankshaft structure

Abstract

A crankshaft structure includes a crank pin section, a crank journal section, and a counter weight section arranged between the crank pin section and the crank journal section in a direction of a crankshaft. A crank arm section connecting the crank pin section and the crank journal section is formed with each of lateral edge portions extending substantially along a circumscribed tangential line connecting a base of the crank pin section and a base of the crank journal section when viewed in the direction of the crankshaft. Each of the lateral edge portions of the crank arm section includes an edge groove having a length extending between a central axis of the crank pin section and a central axis of the crank journal section when viewed in a direction to cross the crankshaft. The edge groove has a groove bottom portion formed between two reinforcing ribs.

Dependencies are inferred from the claim text.