1 前言回顾70年代后期,当时只在高功率装置范围内为燃用重油经济运行的柴油机规定了比较低的极限。80年代初期,由于原油市场形势的变化促使重油也用于较小型的柴油机。为了从较低的燃料费用中得到好处,不得不使这种发动机与更高的燃烧压力和温度相适应。同时,必须对锻制钢顶锻制轻合金裙的组合式活塞(图1、2)提出更高的要求。这种活塞已经在烧粗柴油和重油的中速柴油机上成功地使用了20多年,今后还将如此。这种活塞的可靠性 1 Introduction In the late 1970s, relatively low limits were set for diesel engines that ran heavy-fuel economy operations only at high power installations. In the early 1980s, heavy oil was also used in smaller diesel engines due to changes in the crude oil market. In order to benefit from lower fuel costs, this engine has to be adapted to higher combustion pressures and temperatures. In the meantime, higher demands must be placed on the combined pistons forged steel forged light alloy skirts (Figures 1 and 2). The pistons have been successfully used on medium speed diesel engines that burn gas oil and heavy oil for over 20 years and will do so in the future. The reliability of this piston