Improved Load-Carrying Capacity of Crosshead-Pin Bearings by Incorporating Taper Geometry in Oil-Grooves

大型二冲程柴油发动机中的十字头销轴承在苛刻的润滑条件下运行，因为轴承在低速时在小角度内振荡，并且总是受到高的向下载荷。最近的趋势是发动机更紧凑，输出增加，轴承比负荷增加，从而导致润滑严重性显着增加。因此，提高十字头销轴承的承载能力是非常重要的。在本研究中，使用动态加载轴承咬合测试装置进行实验，以澄清的间隙比和油槽的几何形状的承载能力的影响。还测量油膜的电阻以评价油膜形成的程度。主要成果如下：（1）在具有传统油槽的轴承的情况下，间隙比的减小对于增强对整个轴瓦的挤压作用是有效的，从而降低油膜压力。这反过来又增加了承载能力。然而，当间隙比变得太低时，形成足够的流体动力楔膜的能力降低，从而导致承载能力降低;（2）在油槽的两侧上布置优化的锥形几何形状促进了较厚的油膜，而油膜压力仅小幅增加。因此，可以预期承载能力的显著改善;以及（3）通过对向长度为5度和锥角为0.1度的锥形几何形状实现最大承载能力。

The crosshead-pin bearing in large two-stroke diesel engines operates under severe lubrication conditions, because the bearing oscillates within a small angle at a low speed and is always subject to a high downward load. The recent trend towards more compact engines with increased output raises the bearing specific load, thereby causing the lubrication severity to increase significantly. Thus it is very important to improve the load-carrying capacity of the crosshead-pin bearing. In the present study, experiments using a dynamically loaded bearing seizure test apparatus were carried out to clarify the influences of the clearance ratio and the oil-groove geometry on the load-carrying capacity. The electrical resistance of the oil film was also measured to evaluate the extent of the oil film formation. The major results are : (1)In the case of bearings with conventional oil-grooves, a decrease in the clearance ratio is effective in enhancing squeeze action on the entirety of the bearing pads, thereby lowering the oil film pressure. This, in turn, increases the load-carrying capacity. However, when the clearance ratio becomes too low, the ability to form an adequate hydrodynamic wedge film is degraded, thereby causing the load-carrying capacity to decrease ; (2)Incorporating an optimized taper geometry on both sides of the oil-groove promotes a thicker oil film with only a small increase in the oil film pressure. Thus a significant improvement in the load-carrying capacity can be expected ; and (3)The maximum load-carrying capacity is achieved by the taper geometry of a subtended length of 5 degrees and a taper angle of 0.1 degree.