Lubrication performance analysis of crankshaft bush in compressor

The instability of lubricating oil film has a great effect on the wear of friction pairs and carrying capacity of the parts as well as smooth running of the machine. The lubrication system of crankshaft bush plays an important role in the good operation of compressor unit, reduces production cost while improving production efficiency. In this paper, lubrication performance of the crankshaft bush in compressor was investigated. Parameters involved in the lubrication of bush are studied and analyzed systematically during the stable rotation of crankshaft. Effects of lubrication parameters, such as width diameter ratio, crankshaft speed, inlet pressure, attitude angle and the minimum oil film thickness, on the pressure and distribution of lubricant film were discussed. At last, the optimum value and recommended range of some parameters of bush are determined, and the quantization is carried out within a certain range. The results show that two symmetrical distributions of positive and negative high pressure concentrated areas on both sides of bush oil groove can be formed when the crankshaft is stable. The speed and width diameter ratio have a great effect on the maximum pressure value of oil film. The inlet oil pressure and the minimum oil film thickness are the second, and the inlet attitude angle has little effect. With the increase of width diameter ratio, the maximum pressure value of the positive high pressure concentrated area increases, and the negative areas decreases. With the increase of oil inlet pressure, the maximum oil film pressure increases too but the influence is small. With the increasing of minimum oil film thickness, the maximum pressure and carrying capacity of oil film decrease. If the clearance between crankshaft and bush is too small, oil film can't be formed. For the analysis model in this paper, it is recommended that the radius clearance of bush is 0.04 mm. The inlet oil pressure range of lubricating oil is 0.32-0.36 MPa. Those results can be used in the design, testing and evaluation of the crankshaft system in compressor.