CONNECTING STRUCTURE OF PISTON AND CONNECTING ROD

摘要

A cooling oil chamber (5) comprising an annular groove is provided in a lower surface (2b) of a crown portion (2a) of a piston main body (2). A ceiling wall (61a) of an inverted cup-shaped inner sleeve (61) fitted in a skirt portion (2c) of the piston main body (2) is brought into abutment with the lower surface (2b) of the piston crown portion (2a) so as to close the cooling oil chamber (5). An upper half portion of a semi-cylindrical oscillating guide member (9) is inserted into a square hole (60) formed in the ceiling wall (61a) of the inner sleeve (61) so as to be brought into abutment with the lower surface (2b) of the piston crown portion (2a). A pair of arms (16a) having an arc-like cross section are formed on a smaller end portion of a connecting rod (21) in such a manner as to project in a crank shaft direction. A lower half portion of the oscillating guide member (9) is brought into engagement with an upper surface (16a) in the form of a cylindrical concave surface of the pair of arms (16) and a lower surface (16b) of the pair of arms (16) is brought into engagement with a pair of cylindrical recessed portion (23a) provided in an upper end surface of a seat tube (23). The seat tube (23) is fitted into the inner sleeve (61) and the upper end surface of the seat tube (23) is brought into abutment with an intermediate stepped portion (61c) of the inner sleeve (61) and a lower surface of the seat tube (23) is supported on a projecting piece (27) of the skirt portion (2c).