【作者】 姜维；

【导师】 帅石金； 邓晓龙；

【作者基本信息】 清华大学 ， 动力工程（专业学位）， 2017， 硕士

【摘要】 为满足国家第四阶段乘用车油耗法规的要求,需要汽车发动机采用一系列的节能措施,包括降低润滑系统的机械损失,如采用可变排量机油泵、润滑油匹配优化、润滑油快速温升等措施来实现发动机的节能。可变排量机油泵节能的依据是按需供给,要求精确了解发动机各用油零部件的需求。本文对这些需求进行了分析,发现掌握液压挺柱和可变气门正时等的精确需求存在较大难度,但通过控制策略优化等措施,可降低这些需求。另外,对曲轴轴颈的用油需求进行了详细计算,得出用油量随转速呈加速上升的趋势,通过台架耐久试验验证了额定工况的供油压力可降至300kPa的低水平。本文列举了常见的可变排量机油泵的类型,重点对各型叶片泵进行了研究。结果表明,一级可变排量机油泵在乘用车常用的低转速、低负荷工况下的节能潜力有限;电磁阀式二级可变排量机油泵是目前性价比最高的方案,其主要节能区间与常用工况吻合。理论计算和台架测试表明,使用电磁阀式二级可变排量机油泵在90℃、2000r/min时可降低1N?m的摩擦功,由此预测在新欧洲驾驶循环(NEDC)中可降油耗1.5%左右。另外,通过其高、低压模式的切换,可实现活塞冷却喷嘴喷油时机的灵活控制。润滑油匹配优化的主要目的是减少摩擦阻力,包括使用减摩剂与降低粘度等级两个途径。本文分析了减摩剂用量以及粘度等级从40降至30与20对摩擦阻力的影响,并通过发动机台架摩擦功测试以及整车NEDC循环测试得出其节能潜力在2%以上。最后,本文对润滑油的快速温升进行了初步分析,发现电加热没有节能收益,而排气加热是降低摩擦阻力的有效手段,但需要解决加热系统的成本问题。更多还原

【Abstract】 With the release of China fourth stage fuel consumption regulation,a series of measures has been adopted by passenger car companies to save energy,which include the mechanical loss reduction of lubrication system,such as using variable displacement oil pump,matching between oil and lubrication system,oil rapid warm up,etc,to achieve saving engine energy.Variable displacement pump energy saving is based on on-demand supply,requiring accurate understanding of the engine oil demand components.After analyzing these demands,it is found that it is difficult to master the exact requirements of hydraulic tappet and variable valve timing,but these requirements can be reduced by controlling strategy optimization.In addition,the crankshaft oil demand is calculated in detail.It is found that the oil consumption increased with engine speed.Through engine bench tests,the oil pressure under the rated conditions can be reduced to the low level of 300 kPa.This thesis analyzes different types of variable displacement pumps,and focuses on vane pumps.The results show that the energy saving potential of one stage variable displacement pump under the low speed and low load conditions of passenger vehicles is limited.Solenoid valve two stages variable displacement pump has currently the highest cost efficiency,with good matching between its main energy saving zone and common running conditions.The theoretical calculation and bench test shows that 1N·m torque reduction can be achieved using the solenoid valve pump at 90℃,2000r/min,resulting in about 1.5% fuel consumption reduction in the new European driving cycle(NEDC).In addition,through the switch of its high and low pressure mode,the flexible control of the injection timing of the piston cooling nozzle can be realized.The main objective of lubricant matching optimization is to reduce the friction resistance,including the use of anti friction agents and the reduction of viscosity grade.In this paper,the influence of the amount of antifriction agent and the viscosity grade from 40 to 30 and 20 on friction resistance is analyzed,and its energy saving potential is above 2% through the engine bench test and the vehicle NEDC cycle test.Finally,the rapid warm up of lubricating oil is roughly studied.It’s found the electric heating has no energy-saving benefits,while the exhaust heating is an effective means to reduce the friction resistance,but it needs to solve the cost problem of the heating system.更多还原