Patent ID: 6978757

Claim:
A lubrication structure for a splash lubrication in an engine having a cylinder, a piston provided in the cylinder, a crank case, a crank shaft having a crank pin, the crank shaft being rotatably supported in the crank case, and a connecting rod for connecting the piston and the crank shaft so as to allow the piston to reciprocatingly move in the cylinder, the connecting rod having a small end and a big end, the small end being linked with the piston, the big end receiving the crank pin with an inner peripheral surface of the big end in contact with an outer peripheral surface of the crank pin so as to rotate with respect to each other, the lubrication structure comprising: an oil collector formed as a depression in the outer peripheral surface of the crank pin approximately at the center of the crank pin in an axial direction, the oil collector being displaced from an explosive force in an expansion cycle of the engine, transmitted from the piston via the connecting rod; and an oil groove provided on the big end of the connecting rod, the oil groove having a first and a second end, the first end being open in the inner peripheral surface approximately at the center thereof in an axial direction, the second end being open into the crank case, the oil collector receiving oil stored in the crank case and the oil being transferred to the oil groove; wherein the connecting rod comprises a rod portion which integrally connects the small end with the big end, the big end being divided into a first half extending from the rod portion and second half along a diameter line of the inner peripheral surface of the big end, and the oil groove being formed in the second half.