| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent peeling of a bonded surface around an opening when machining the opening of an oil passage, from being increased after a piston is applied to an internal combustion engine, in the piston with a piston cooling channel forming annular body buried therein. Ž<P>SOLUTION: In the piston cooling channel forming annular body 10, opening forming positions 12 formed in the wall portion of the annular body are surrounded by a peripheral wall in a stepped manner through axial walls 16 formed along the axial direction of the whole piston cooling channel forming annular body 10. Even if the wall around the openings is peeled from a joint surface with a piston body 4, therefore, inertial force by reciprocating motion is changed from peeling force to shearing force with respect to the axial walls 16 when the peeled wall reaches the peripheral axial walls 16 by the reciprocating motion of the piston body 4. Hence, peeling of the joint surface between the axial walls 16 and the piston body 4 is not increased any more, and peeling is prevented. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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