基于节能竞技比赛的发动机节能技术研究

以中国节能竞技大赛为设计背景,对本田125cc发动机进行改造,在满足竞赛动力性要求的基础上,来降低燃油消耗率,提高燃油经济性能。以此目标,对发动机结构进行了优化、改造,并采用电控燃油喷射系统来降低油耗;同时在独立研发的发动机综合性能实验台上进行改装发动机的燃油经济性实验,并对实验数据进行拟合,得到改装发动机的燃油经济性曲线,并对发动机燃油经济性进行了评估。     

机油黏度等级对发动机机械损失的影响研究

针对某自然吸气发动机,对不同黏度等级的多级汽油机油进行测试试验,评价高温黏度、低温黏度等级对发动机机械损失及燃油经济性的影响。     

发动机冷却系统降油耗的优化设计及验证

发动机冷却系统,影响着发动机的燃油经济性、加速性、可靠性以及使用寿命。为此,针对某机型发动机,使用开关式水泵与电动阀节温器进行冷却系统优化。为确保其理论优势,采用NEDC工况下的试验进行验证,为优化设计提供了依据。     

降低弧齿锥齿轮风阻损失仿真

齿轮的风阻损失是齿轮传动机械损失的重要组成部分,而降低弧齿锥齿轮的风阻损失可以提高航空发动机的燃油经济性,很有意义。对弧齿锥齿轮的风阻损失进行仿真分析,研究了4种不同结构导流板对风阻损失的影响,同时考虑了导流板与齿轮间距离以及轮齿线速度的影响,并以某航空发动机中央传动弧齿锥齿轮为例,对导流板的工程应用进行了初步评估。结果表明,应用合适结构的导流板可以有效降低风阻损失约75%。当导流板结构不合适时可能增加风阻损失约25%。导流板与齿轮间距离越小,对风阻损失的影响越大。当轮齿线速度不同时,导流板对风阻损失的影响具有相同的趋势。     

基于拖拉机燃油经济性HMCVT换挡规律的研究

通过分析拖拉机燃油经济性指标和拖拉机经济性的影响因素,提出一种以拖拉机燃油消耗率最低和牵引效率最高为目标的燃油经济性换挡规律。根据拖拉机燃油最佳经济性,结合液压机械无级变速器(Hydraulic mechanical continuously variable transmission,HMCVT)的结构和传动特点,阐明实现拖拉机燃油经济性的要求。探究一种发动机燃油消耗率和液压机械无级变速器的传动效率之比最小为目标的经济性最佳的HMCVT下的发动机转速转矩曲线,通过与发动机外特性曲线比较,可以使各挡位都处于油耗最低的经济性区域,并保证拖拉机的速度稳定,符合经济性换挡规律。     

增程式电动汽车能量管理策略控制参数优化研究

为了进一步提高增程式电动汽车发动机的燃油经济性和排放性,对基本遗传算法进行改进,生成改进的自适应遗传算法,并将其应用于增程式电动汽车能量管理策略控制参数的优化。通过权值函数的方法将燃油消耗和排放多目标优化问题转化为单目标优化问题,并采用罚函数的方法对工况运行前后蓄电池荷电状态的增量进行约束,对增程式电动汽车发动机燃油经济性和排放性进行优化仿真。仿真结果表明,采用改进的自适应遗传算法能够有效优化增程式电动汽车能量管理系统的控制参数,使发动机的燃油经济性和排放性得到较大的提高。     

降低摩擦功耗的汽油机活塞组件优化设计

本文着重探讨在降低摩擦功耗提高燃油经济性方面,马勒公司在汽油机活塞组件(分别从活塞、活塞环组和活塞销)上提出的优化设计方案,在理论分析和发动机台架试验数据的共同支撑下,完成对发动机降低摩擦功耗提高燃油经济性方面的升级换代工作,从而保证该款发动机满足客户新一阶段燃油耗要求,延长该发动机的生命周期。     

货车传动系参数优化匹配分析

汽车动力装置参数对其动力性和燃油经济性有很大影响。对汽车发动机与传动系的优化匹配进行了理论分析并采用偏置等比级数分配变速器速比;并以某轻型货车为例,基于GT-drive建立仿真模型,分析几种优化方案;最终选取最佳优化方案,相较原车在保证动力性基础上提高了燃油经济性。     

双模式消声器性能优化设计方法的研究

双模式排气消声器在发动机低速转动时具有良好的低频消声效果,而在发动机高速转动时能够减少发动机传递功率的损失,提高燃油经济性,但却很难保证消声器的降噪量。降噪量和功率损失两者之间存在相互矛盾,为解决这一问题,现采用正交试验的方法和计算机仿真模拟的方式,通过对双模式消声器的内部结构参数进行设计和筛选,得出最佳的设计方案。分析结果表明,优化后的消声器在不影响发动机低转速消声量的同时,可使发动机功率损失减少将近一半。     

基于冷却热管理的商用车燃油经济性提升试验研究

本文以国内某中型载货商用车为研究对象,开展基于冷却系统热管理优化的整车燃油经济性提升试验研究。通过提升发动机节温器开启温度,提高了发动机的运行工作水温,降低了发动机本体摩擦功的消耗;通过优化电控硅油离合风扇控制策略,实现了发动机水温的精确控制,减少了风扇的运行时间,降低了风扇的运行功耗;整体上,综合节温器开启温度的提升、电控硅油离合风扇的控制策略优化,完成了对整车冷却系统热管理的控制,实现了整车燃油经济性的提升。     

Novel method of measuring tappet rotation and the effect of lubricant rheology

One of the main drivers for developing lubricant technology is engine durability. Researchers and scientists are using new technologies, materials and advanced lubricant formulations to reduce overall engine friction and wear. One of the main engine tribological components is the valve train. This is one of the most challenging components to lubricate effectively because of the higher contact loadings and accounts for 10–20% of the total engine friction loss. The two main factors affecting the performance of engine valve trains are wear and friction, and a wide range of mechanical configurations are used to improve these. For example, direct-acting overhead camshaft valve train configurations use a rotating tappet design. Normally, the tappet is slightly offset from the cams and the cam is slightly conical to match the domed tappet to facilitate tappet rotation for even wear and to reduce slippage. In this paper, a novel innovative technique has been described to monitor tappet rotation in a real production engine having a direct overhead cam–tappet arrangement. The monitoring technique was applied to a VW Tdi engine head, and tests were carried out under different operating conditions. Lubricant compositions, oil temperature, pressure and camshaft speeds on tappet rotation were measured and all are shown to have an effect. The balance of forces between the cam–tappet and tappet-bore was found to be interlinked and the design of the hydraulic lash adjuster had a significant effect.This unique tappet rotation monitoring system can be used on most of the direct overhead camshaft engines, with minor engine modifications, to measure lubricant and hardware effects under both motored and fired conditions.     

Analysis of engine temperature and energy flow in diesel engine using engine thermal management

Recently, precise analysis of energy flow in engines has become necessary to improve fuel economy. An integrated engine thermal management model, which is introduced in this paper, is suitable for that process. The model consists of six sub-models for thermal mass, coolant, lubricant, heat transfer, friction, and exhaust. The sub-models are coupled to each other and they exchange heat and signals. Combustion energy flow analysis and temperature estimation of the engine components and working fluids were simulated under various conditions. Simulation results were compared with experimental data and they showed good agreement. Then, a variable-speed water pump (VSWP) to control coolant flow was applied in place of a conventional water pump. Engine warm-up time decreased with proper coolant flow control, and fuel economy could be improved by 2.5%.     

多目标优化设计在配气机构凸轮型线中的应用

分析了发动机配气机构凸轮型线设计要求和型线选择,建立了凸轮型线多目标优化数学模型,基于Matlab软件编制了凸轮型线进行多目标优化设计的程序。给出了计算实例,实例表明通过优化改善了挺柱运动的平滑性,提高了配气机构的性能。     

发动机配气机构系统的动力学建模及仿真分析

针对发动机配气机构系统,在ADAMS／Engine软件中建立了其虚拟模型,在此基础上,对该机构进行了仿真分析,得到了气门的升程、速度、加速度和摇臂与挺柱的接触力等特性曲线,为配气机构动态性能的评价和优化提出了理论依据,从而为虚拟样机技术在新产品开发中的应用提供了有效方法。     

A new electromagnetic engine valve actuator with less energy consumption for variable valve timing

A variable valve timing (VVT) can improve fuel efficiency, reduce CO2 emissions and increase torque output enabling optimization of these outputs at different engine conditions. To achieve VVT in internal combustion engine, new devices such as mechanical, hydraulic, motor-driven and electromagnetic actuators have been developed in past years to replace the conventional camshaft valve train system used currently. Among these, the electromagnetic actuator using solenoids is the most advanced system to provide the most flexibility to valve timing, but it has critical drawback of high power consumption. In this paper, a new electromagnetic engine valve actuator that uses permanent magnets to latch the valve is introduced.     

发动机配气机构系统的动力学建模及仿真分析

针对发动机配气机构系统,在ADAMS/Engine软件中建立了其虚拟模型,在此基础上,对该机构进行了仿真分析,得到了气门的升程、速度、加速度和摇臂与挺柱的接触力等特性曲线,为配气机构动态性能的评价和优化提出了理论依据,从而为虚拟样机技术在新产品开发中的应用提供了有效方法.     

DLC涂层改善气门挺柱摩擦学性能的试验研究

为探求DLC涂层对气门挺柱摩擦学性能的影响,制备了三种不同表面处理的气门挺柱,搭建了配气机构试验台架,对比分析了不同顶面处理方法的气门挺柱在不同转速和缸盖温度下的摩擦功耗;测试了试验前后气门挺柱和凸轮的表面形态,研究了DLC涂层表面特性及其耐磨损特性。试验结果表明,DLC涂层能够减小气门挺柱表面粗糙度,含Si的DLC涂层表面粗糙度极小;气门挺柱与凸轮之间的摩擦力矩随着凸轮轴转速上升逐渐减小,随着缸盖温度上升逐渐增大;相对于传统碳氮共渗气门挺柱,DLC涂层能有效减小摩擦损失,含Si的DLC涂层能减小高达20%的摩擦损失;无涂层气门挺柱和不含Si的DLC涂层气门挺柱的耐磨性较差,含Si的DLC涂层具有极好的耐磨性。     

基于响应曲面法的煤油发动机气门正时优化

利用基于仿真的响应曲面优化方法,对改型的煤油活塞发动机气门正时多目标优化问题进行了研究。建立了发动机性能仿真模型,以进气/排气正时、点火提前角为优化变量,以提高有效功率和降低燃油消耗率为设计目标进行了响应曲面优化。分析结果表明：相对于原汽油机,改型的煤油机进气门开启时刻要推迟,排气门关闭时刻要迟后,并且要提前一定的点火提前角,以得到最佳的发动机性能;同时,应用响应曲面法可以提升仿真优化的效率。     

中速柴油机冷却系统恒温控制设计与研究

针对柴油机不同的工况对冷却水温度要求不同,原冷却系统不能随工况的变化自动调节温度,设计了柴油机智能冷却系统恒温控制系统。通过热平衡实验获得柴油机各工况最佳工作状态的冷却水温度和流量,利用单片机控制变频器水泵转速和电控三通旁通阀的开度对冷却水温度自动控制。实验结果表明:该系统可以随柴油机工况变化将冷却水温度恒定控制在最佳工作温度,达到了节油效果,最大节油率为5.4%,平均节油率为3.6%。     

A study of the measurement of surface temperature at a cam/tappet contact

Cam/tappet wear is one of the most difficult reliability and durability problems to predict during the development of a prototype engine valve‐train system. In the present study, the cam/tappet surface temperature was measured and calculated to determine the effect of surface temperature on the lubricating conditions at a cam/tappet contact. The measurement method, sometimes called the dynamic thermocouple technique, was based on the Seebeck effect: by using different materials for the cam and tappet, the cam/tappet contact point becomes the hot junction of a ‘thermocouple’. The cam/tappet contact surface temperature can therefore be measured continuously. The measured temperature results show good agreement with predictions. Temperature spikes, however, were not found in the test using new oil, but were shown by the theoretical model. Such results indicate that the cam/tappet interface operates in effective lubricating conditions, even when the oil temperature is relatively high. Further research with degraded oil supplied at high temperature is needed for a thorough understanding of abnormal cam wear.