| 摘要 |
A multi-cylinder engine is provided with a crankcase integrated cylinder block which includes a cylinder block including a plurality of cylinder bores, a plurality of crank chambers formed by an upper crankcase and a lower crankcase, a bulkhead that partitions between the cylinder bores and the crank chambers, and a honing release portion having a cylindrical honing release surface formed continuously with the cylinder bore in the upper crankcase and the bulkhead. The honing release surface forms an arcuate recessed portion in the bulkhead, the bulkhead is formed with a communication hole that includes a first opening edge on a side of the cylinder bore, a second opening edge on a side of the crank chamber having an opening width decreasing with a distance from the cylinder bore, and a third opening edge that extends substantially in parallel with the cylinder axis, the communication hole being formed from the cylinder bore to the recessed portion so as to establish communication between the cylinder bores and the crank chambers, and the second opening edge is formed from the cylinder bore to the recessed portion to prevent the honing release surface from being divided. |
