Patent ID: 8061325

Claim:
An oil pan structure for an engine, the oil pan structure comprising: an oil pan flange for being fastened with bolts to an undersurface of an engine crankcase; a bottom wall that forms a bottom part of an engine; a left side wall and a right side wall extending in a longitudinal direction of the engine, a front side wall and a rear side wall extending in a transverse direction of the engine, wherein each of the left side wall, the right side wall, the front side wall, and the rear side wall extends between an edge of the bottom wall and the oil pan flange such that the oil pan structure defines an internal space and is capable of storing engine-internal oil that is stirred in the internal space, wherein each of the bottom wall, the left side wall, the right side wall, the front side wall, and the rear side wall comprises a plurality of reinforcement beads which swell at a middle part thereof with a corrugation shape toward the internal space of the oil pan structure, wherein the reinforcement beads extend from the bottom wall toward the left or right side wall, or from the bottom wall toward the front or rear side wall, and wherein the reinforcement beads are substantially U-shaped beads which each comprise a closed end, a tunnel-shaped part, and an open end, the tunnel-shaped part being disposed at a middle part of the reinforcement bead and swelling toward the internal space of the oil pan structure, and the closed end forming a smooth transition between the tunnel-shaped part of the reinforcement bead and a surface of the oil pan structure.