| 摘要 |
PROBLEM TO BE SOLVED: To provide a cylinder block that excels in rigidity of its skirt portion and promotes the return of oil lubricating a cylinder head to an oil pan. SOLUTION: A cylinder block 1 comprises a pair of skirt walls 3 arranged on both sides of a crankshaft, and a plurality of crank journal portions 4 integrally formed to interconnect the inner surfaces of the pair skirt walls 3 and supporting the crank shaft. A section between a portion (journal connecting portion) J connected to the crank journal portion 4 and an adjacent journal connecting portion J has multi-wall structure where more than two walls 21 and 22 are integrally formed. The walls 21 and 22 constituting the multi-wall structure are mutually connected at the journal connecting portion J, and a clearance between the walls 21 and 22 is an oil return passage 32 for returning the oil to the oil pan. COPYRIGHT: (C)2004,JPO&NCIPI
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