| 摘要 |
PURPOSE:To enhance the efficiency of radiation from a cast iron sleeve, by removing a cast skin on the outer peripheral surface of a cast iron sleeve adapted to be cast in an aluminum alloy cylinder barrel, all over the surface thereof, and by forming annular or spiral come-off checking grooves in the outer peripheral surface of the sleeve. 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. Before being cast into the barrel, the cast skin of each sleeve 3 is removed all over the outer peripheral surface thereof by means of a machining work. Further, a plurality of annular come-off checking grooves (g) having a minor arc cross-sectioned shape are formed in the outer peripheral surface of the sleeve at predetermined pitches at least over a predetermined distance from the cylinder head side end section by mean of a machining work. |
