| 摘要 |
PURPOSE:To reduce the max. stress produced in pin bosses by forming tapered surfaces having the max. diameter at the connecting rod side end faces of the pin bosses on the inner peripheral surfaces of the pin bosses supporting a piston pin. CONSTITUTION:When a pair of left and right connecting rods 7 are connected to a piston 4 having an elliptical cross section through a single piston pin 6, the connecting rod 7 side halves on the inner peripheral surfaces of respective pin bosses 8, 9 are formed with tapered surfaces 8a, 9a which are expanded to the connecting rod 7 side to have the max. diameter at the connecting rod 7 side end faces of respective pin bosses 8, 9. Thus, under no-load condition, a wedge- shaped sectional gap 11 is formed on fitting surfaces of the pin 6 and the pin bosses 8, 9. By such a constitution, in the sxplosion stroke, upward bending deflection is produced in the pin 6 between the bosses 8, 9 while stress acting on the bosses 8, 9 are dispersed since the upper surface of the pin 6 sequentially bears against the tapered surfaces 8a, 9a. |
