考虑热弹性效应的内燃机曲轴主轴承润滑性能研究

Study on Lubrication Performances of Crankshaft Main Bearing for Internal Combustion Engine Considering Thermo-elastohydrodynamic Effect

建立某V型8缸内燃机曲轴主轴承的热弹性流体动力学(TEHD)仿真模型,并对各主轴承润滑状况进行分析。针对润滑状况较差的第3主轴承,分析油槽开设方案、相对间隙、轴承宽度和润滑油特性对其润滑状况的影响。结果表明,随着相对间隙的增大,主轴承最小油膜厚度先增大后减小,当间隙过小时,摩擦功耗较大,润滑油温度较高,油膜厚度小;当间隙过大时,泄漏的润滑油较多,油膜厚度减小,且冲击振动大。主轴承的宽径比要适当,轴承宽度过小,油膜厚度偏小,承载能力过低;轴承宽度过大,润滑面积增大,润滑油流量相对减小,摩擦产生热量增加。研究表明,该主轴承适宜在上瓦开设油槽,轴承间隙选为25μm,宽度选为30 mm较好。

The thermo-elastohydrodynamic （TEHD） simulation model of a crankshaft main bearing for certain V-8 diesel engine was established, and all the main beating lubrication conditions were analyzed. Influences of arrangement of oil grooves, relative gaps, width of bearing and characteristics of oil on the lubrication condition were analyzed on the third main bearing, which was in a awful lubrication. The results show that along with increasing of relative gap, the minimum oil film thickness is firstly increased and then decreased. The bigger friction power consumption, higher oil temperature and thinner oil film are resulted from the relative over small gap. However,more oil leakage ,thinner oil film and serious impact vibration are caused when the gap is too large. Width-diameter ratio of main bearing should be appropriate. Thinner oil film and lower carrying capacity is led by over smaller bearing width. While a wider bearing gap, the lubrication area is in- creased, and lower oil flow rate and greater friction heat are resulted. The research shows that the oil-groove of this main bearing should be opened and located in the upper shell with the bearing gap and width of 25 μm and 30 mm respectively.