| 摘要 |
PURPOSE:To make substantially uniform residual casting stress in a cast iron sleeve cast in each aluminum alloy cylinder barrel around the circumference thereof, by forming the cast iron sleeve in a substantially elliptic cross-sectioned shape having its major axis extended in parallel with the direction in which the cylinder barrels are arranged. CONSTITUTION:A Siamease type cylinder block is composed of a Siamease cylinder barrel 1 formed by coupling four cylinder barrels 11-14, an aluminum alloy cylinder block body 2 consisting of an outer wall 4 surrounding the cylinder barrel 1 and a crankcasing 5 and cast iron sleeves 3 each cast in each of the barrels 11-14. In this arrangement, each sleeve 3 is formed in a substantially elliptic cross-sectioned shape with its major axis being extended in parallel with the direction in which the barrels 11-14 are arranged, by being subjected to solidifying contraction force of the barrels 11-14. Thereby, residual casting stress in each sleeve 3 may be made to be uniform around the circumference thereof, and the thermal expansion of the sleeve 3 in the circumferential direction may be made to be uniform when the sleeve 3 is subsequently subjected to a true circle fabrication. |
