燃油稀释低黏度机油对柴油机缸套活塞环润滑性能的影响  

Effects of fuel diluting low-viscosity oil on lubrication property of cylinder liner piston ring in diesel engine

作　　者：徐波 尹必峰[1] 贾和坤[1] 魏明亮[2] 石坤鹏[2] Xu Bo;Yin Bifeng;Jia Hekun;Wei Mingliang;Shi Kunpeng(School of Automotive and Traffic Engineering,Jiangsu University,Zhenjiang 212013,China;State Key Laboratory of Power System of Tractor,YTO Group Corporation,Luoyang 471000,China)

机构地区：[1]江苏大学汽车与交通工程学院,镇江212013 [2]中国一拖集团有限公司拖拉机动力系统国家重点实验室,洛阳471000

出　　处：《农业工程学报》2021年第11期60-66,共7页Transactions of the Chinese Society of Agricultural Engineering

基　　金：拖拉机动力系统国家重点实验室开放基金(SKT2020003);江苏省研究生科研与实践创新计划(KYCX19_1597)。

摘　　要：为研究燃油稀释低黏度润滑油对缸套活塞环润滑性能的影响,该研究以农用柴油机为研究对象,基于燃油湿壁现象考察了燃油稀释低黏度润滑油对混合液的黏度变化影响。试验结果显示,随着燃油稀释率增大,混合液的动力黏度呈现先急剧下降后缓慢下降的变化规律,稀释率从0增加到10%,动力黏度降幅达44.9%,表明少量柴油稀释低黏度润滑油将导致黏度迅速降低。通过构建缸套-活塞环润滑摩擦理论模型,采用数值计算方法探究了燃油湿壁效应对缸套-活塞环摩擦性能的影响机理。模拟计算结果显示,随稀释率的增加,缸套-活塞环之间的油膜厚度变薄,流体动压润滑区间不断缩小,而混合润滑区间不断扩大,导致摩擦副表面微凸体接触增多,特别是在压缩行程上止点附近,缸套-活塞环的摩擦力随着稀释率增加而增大;而缸套-活塞环摩擦副的循环摩擦损失随稀释率增大呈现先降低后升高的趋势,稀释率为10%时摩擦损失最小。通过搭建发动机测试台架进行倒拖试验发现,当稀释率从0增大到30%时倒拖转矩呈现先减小后增大的趋势,且当稀释率为10%时倒拖转矩最小,验证了不同燃油稀释率下倒拖转矩变化与模拟计算结果的一致性。在发动机中应用低黏度润滑油,应控制其稀释率低于20%,以保持必要的润滑作用。研究结果可为为低黏度润滑油的推广应用提供指导。The cylinder liner-piston ring is one of the most significant friction pairs in diesel engines.This study aims to explore the effects of fuel diluting low-viscosity oil on the lubrication property.Taking a farm diesel engine as the research object,the typical wall wetting was utilized to clarify the variation in the lubricant viscosity of diluting oil.The results indicated that the lubricant viscosity first dropped rapidly,and then remained stable,as the diluting ratio increased.Specifically,the lubricant viscosity dramatically declined by 44.9%,when the diluting ratio of oil rose from 0 to 10%,whereas,the dynamic viscosity decreased by 38.8%when the diluting ratio of oil was continuously elevated from 10%to 30%.It infers that there was a great effect of a little fuel diluting in the lubricating oil on the lubricant viscosity,while this effect became weaker than before when the diluting ratio reached a critical value.A mixed lubrication model was then built to investigate the tribological properties of the cylinder liner-piston ring,where the percentage of fuel diluting lubricant was changing.The simulated data showed that the minimum thickness ratio of fuel film decreased significantly,as the diluting ratio rose,indicating that the specific thickness of fuel film decreased between the cylinder liner-piston rings in a diesel engine.The area of hydrodynamic lubrication also decreased on the friction pair of the cylinder liner-piston rings,while the mixed lubrication area expanded with the increase of the fuel dilution ratio.Furthermore,the thickness of the oil film was too thin between the friction pair of cylinder liner and piston rings,especially at the diluting ratio of 30%.It was found that the whole process was in a mixed lubrication state,where the fuel lubrication was not enough.The hydrodynamic lubrication was therefore dominated by the mixed lubrication between cylinder liner and piston ring when the external load of the piston ring was relatively small.Even if the viscosity of lubricant was very low,a ce

关 键 词：柴油机 摩擦 稀释 缸套 活塞环 润滑 

分 类 号：TH117.2[机械工程—机械设计及理论]