| 摘要 |
PROBLEM TO BE SOLVED: To provide a cylinder block structure suppressing a variation in an effect of reducing a pumping loss in a crank chamber. SOLUTION: This cylinder block structure includes: a front wall vent hole 30 and a rear wall vent hole 40 which are respectively formed in an engine front wall 3 and an engine rear wall 4 provided at the front and rear ends of a cylinder block body 2, and allowing first and second external chambers 14 respectively located adjacently to the walls 3, 4 and provided outside of the cylinder block 2 and crank chambers 6 to communicate with each other; and journal wall vent holes 50 formed in journal walls 5 for mutually partitioning the crank chambers 6 and allowing the adjacent crank chambers 5 to communicate with each other. The flow passage cross-sectional areas of the front wall vent hole 30, rear wall vent hole 40 and journal wall vent holes 50 are equalized to each other, respectively. COPYRIGHT: (C)2011,JPO&INPIT
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