| 摘要 |
PURPOSE:To check the diametrical expansion of a piston skirt shoulder part as well as to prevent its seizure or binding with a cylinder bore from occurring, by complexly strengthening a portion lying between an oil ring groove and a skirt part looking in the piston axial direction, with a ringlike reinforced fiber. CONSTITUTION:Looking in the direction of a piston axis 8, a portion lying between an oil ring groove 7 of a side wall 4 and a skirt 12, namely, a skirt shoulder part 13 is complexly strengthened by an alumina continuous fiber annularly around the axis 8 at both of a first range 14 vertically extending substantially to an axis 11 of a piston hole 10 and a second range 16 circularly extending substantially along an outer circumferential surface 15 of the side of a piston between both ends of the said range 14. At the range 14, there is provided a bent part 17 at which the shoulder part 13 bypasses the piston hole 10.
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