| 摘要 |
PROBLEM TO BE SOLVED: To improve thermal conductivity and cooling capability, and reduce the number of parts by carrying out flame spraying on a crank hole inner surface of a cylinder block made of aluminum alloy including Si having a specified quantity, and integratedly forming a bearing part. SOLUTION: A cylinder block 1 is casted with aluminum alloy including Si of 15% or more. Primary crystal Si is contained in a matrix so as to provide the block 1 having a good abrasion resistance. A crank hole 2 is worked on a set part, predetermined accuracy is ensured, and then, Al-Pb alloy is flame sprayed on an inner circumferential surface to form a flame-spray film 3. Its surface is ground so as to provide a bearing part 4. When a Si containing quantity is less than 15%, necessary abrasion resistance property is not ensured. When it is more than 25%, workability of the block 1 is deteriorated. The flame spray film 3 is the same Al alloy as the block 1 to improve close adhesiveness. The necessity of an individual bearing metal is eliminated, the number of parts are reduced, the bearing part 4 is formed integratedly with the block 1, thermal conductivity is improved, and its cooling efficiency is improved.
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