PURPOSE: To both prevent occurrence of resonance vibration and increase rigidity of an oil pan as a whole, by arranging plural beads in an unequal pitch to the oil pan of an engine and obtaining a different frequency of natural vibration in a surface divided by the bead.
CONSTITUTION: An oil pan 1 is mounted to the lower part of an engine E by tightening members 2, and vertically extended plural beads 5 are parallelly formed in an unequal pitch to side surfaces of the oil pan 1. The plural beads 5, being formed, can improve rigidity of the total unit of the oil pan 1 to eliminate low frequency vibration. Further each bead 5 is arranged in an unequal pitch and provided all with different distances l1Wl4 of the beads 5, then area of divided surfaces formed between each bead 5 is different from each other also with a frequency of natural vibration different. Accordingly, a noise due to a resonance phenomenon simultaneously with a noise due to a low frequency can be reduced and eliminated.
MISUMI MASANORI
NAKANISHI NOBUYUKI
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