一、前言东风_4型内燃机车(以下简称东风_4机车)到目前为止已有400多台在线路上运用,最长的已有七年多了。运用中16240Z型柴油机暴露了不少问题,有的是材料、工艺上的问题,有的是设计结构和参数选择上的问题。其中问题较大的,如机体裂纹、连杆大端变形及结合面牙齿裂纹、连杆螺栓断、气阀下陷等。而这些问题的产生,都是与柴油机运动件的往复惯性力有着密切的关系。与国外同类型的中速柴油 I. Introduction Dongfeng _4 diesel locomotive (hereinafter referred to as Dongfeng _4 locomotive) has so far been used in more than 400 units of the line, the longest has been more than seven years. The use of 16240Z diesel engine exposed a lot of problems, some of the materials, process problems, some of the design structure and parameter selection problems. One of the larger problems, such as the body crack, connecting rod deformation and the surface of the tooth crack, connecting rod bolt, valve sag and so on. And these problems are generated, and diesel reciprocating inertia forces are closely related. With the same type of foreign medium-speed diesel