机车柴油机喷油泵凸轮接触应力分析

针对机车柴油机喷油泵凸轮表面常出现点蚀、麻点、剥落等损伤问题,开展喷油泵凸轮轮廓升程段的接触应力研究,分析导致喷油泵凸轮表面失效的原因。以16V240ZJB型柴油机为例,通过对油泵凸轮轮廓曲线进行几何分析,导出凸轮升程段的运动方程。采用弹性力学中的赫兹理论,建立油泵凸轮接触应力的计算式,并通过计算机编程,从理论上计算和分析喷油泵凸轮表面的接触应力。理论计算结果表明:喷油泵凸轮的接触应力虽高达1 421.655 MPa,但并未超过许用应力值。因此建议从材料加工工艺方面查找原因,提高凸轮表面加工质量,并采用复合强化工艺,进一步加大喷油泵凸轮表面的强度。     

Effect on friction of engine oil seal with engine oil viscosity

Low viscosity engine oil can improve a vehicle’s fuel economy by decreasing the friction between the engine components. Frictional torque varies with the velocity change due to different viscosity characteristics of SAE grade 5W-20, 5W-30 and 5W-40 engine oils. The viscosity for each of these grades was measured to outline the effect low viscosity engine oils have on engine friction, which may lead to improved fuel economy. Engine oil seal frictional torque increases with the shaft rotational speed for all three engine oil grades. A decrease in engine oil seal frictional torque was confirmed when low viscosity engine oil was used. Also, the leak-free performance of the engine oil with the seal satisfied the life limit durability test criteria. Thus, low viscosity engine oil may be used to improve fuel economy by decreasing the frictional loss of the engine oil seal while having no negative impact on performance due to leak-free functioning.     

利用Cruise软件进行整车动力性和燃油经济性仿真分析

本文论述了利用CRUISE软件进行汽车建模的过程,并对某重型商用车的动力性和燃油经济性进行了仿真分析。     

天然气发动机冷却系统校核

商要:发动机冷却系统的作用是使发动机的温度在所有工况下均保持在适当的范围内。冷却系统不仅要防止发动机过热,也要防止发动机过冷。本文主要是对某重卡车型的发动机冷却系统进行了校核计算,为整个车型的匹配计算提供数据支持。     

甲醇汽油机怠速稀燃特性的试验研究

为改善传统汽油机怠速稀燃的燃烧与排放特性,在1台加装了电控甲醇喷射系统的汽油机上对燃用汽油(M0)、50%质量比例甲醇汽油(M50)和纯甲醇(M100)3种燃料的发动机的怠速稀燃特性进行了试验研究。试验先后在过量空气系数a=1.1和a=1.3两组稀燃工况下进行,怠速转速稳定在800r/min左右。试验结果表明:添加甲醇后,两组稀燃工况下指示热效率均有所提升;发动机的火焰发展期、快速燃烧期和平均指示压力的循环变动系数随着甲醇比例的增加而降低;甲醇能够显著降低发动机怠速稀燃工况下的HC和NOx排放,CO2排放随着甲醇含量的增加也略有降低。     

大功率变流器晶闸管烧损的原因与对策

对１０００ＫＷ交直交变流器在地面试验中发生的一些大功率晶闸管烧损的原因进行分析与探讨，产提出了一些相应的对策 。     

船用大功率柴油机新型燃油系统的数值仿真

本文数值仿真了一种适合劣质燃油（重油）的循环式燃油系统（一泵二嘴四针阀），提出了处理喷油器和燃油分配器边界条件的准维模型以及用于喷油泵边界条件的新模型。该燃油系统已应用于MANB&WL60MC／MCE等大功率柴油机。与常规的数值仿真相比，求解管内流动的二队双曲型偏微分方程的边界条件发生了很大变化，这是燃油系统研究的难点和关键。预测结果与试验结果较为一致。本研究还进行了不同功率点变型方案的模拟研究和结构参数的优化设计分析，以满足不同船舶的需要。     

乘用车燃料消耗量检测不确定度评定

基于国内乘用车排放试验室现状,根据《测量不确定度评定与表示》(JJF 1059—1999)中对不确定度的定义和评定要求,将尾气排放测试系统、底盘测功机等仪器和设备、环境条件、标准物质、试验操作等影响测量结果的不确度用于评定汽车燃油消耗量测量精度,通过计算得到了碳平衡法油耗测试结果的扩展不确定度,且表明了该结果的置信范围和程度。     

电喷摩托车供油方式分析及燃油消耗量测量探讨

电喷摩托车供油方式和化油器摩托车截然不同,沿用化油器摩托车发动机的燃油消耗测量方式不能准确进行燃油消耗量的测量,必须根据具体特点,采用正确的方法,才能准确进行电喷摩托车和电喷发动机燃油消耗量的测量。     

Potential of low viscosity oils to reduce CO2 emissions and fuel consumption of urban buses fleets

This paper shows the results of a comparative fleet test the main objective of which was to measure the influence of Low Viscosity Oils (LVO) over the fuel consumption and CO₂ emissions of urban buses. To perform this test, 39 urban buses, classified into candidate and reference groups depending on the engine oil viscosity, covered a 60,000 km mileage corresponding to two rounds of standard Oil Drain Interval (ODI). In the same way, for 9 buses of the 39 buses, the effect of differential LVO over fuel consumption and their interaction with engine LVO was assessed during the second ODI.Test results confirm that the use of LVO could reduce fuel consumption, hence CO₂ emissions. However, special attention should be taken prior to its implementation in a fleet, particularly if the vehicles are powered by engines with high mechanical and thermal stresses during vehicle operation because this could lead to friction loss increase, loss of the potential fuel consumption reduction of LVO and, in the worst scenario, higher rates of engine wear.