| 摘要 |
<p>A reduced-diameter portion (44) with a taper portion (46), a portion whose diameter is reduced in a tapered form, is provided on an inner peripheral wall of a cylinder sleeve (20a, 20b, 20c). On the outer peripheral wall of the top end of the cylinder sleeve (20a, 20b, 20c) is provided a large diameter portion (36a, 36b, 36c) projected outward along the diameter direction. Under the action of a friction stir welding tool (50), the cylinder sleeve (20a, 20b, 20c) inserted in a communication hole (16) of a block body (18) is joined to the block body (18) with the reduced-diameter portion (44) and the large-diameter portion (36a, 36b, 36c) in between. A closed deck-type cylinder block (10) is constructed with the process above. In the cylinder block (10), the gasket face (12) side of a water jacket (22) is closed by the large-diameter portion (36a, 36b, 36c).</p> |
