| 摘要 |
PURPOSE:To improve durability of a piston and save an oil consumption, by providing a number of recesses around a partial outer periphery of the piston and through holes bored in the periphery for circulating the oil. CONSTITUTION:A number of recesses 5 are provided around a partial outer periphery of a piston 3 so as to reduce a heat conduction and to prevent the piston from overheating. A through hole 6 bored in the recess 5 of lower step of uppermost section can not only eliminate the need of an oil ring which has been indispensable in a conventional piston, but also suppress a temperature rise of oil. The latter function is a result of arrangement such that the oil overflowed from the through hole 6 for circulating the oil is settled in the recess 5. Moreover, a zigzag arrangement of the recesses 5 can distribute the oil uniformly, prevent the piston from overheating and maintain the oil viscosity consistently. Furthermore, the present invention can provide to the oil additional advantages such as a reduced frictional resistance, saved consumption, suppressed fouling and extremely extended replacement interval. |
