一种小型二冲程汽油机曲轴箱有限元动态特性分析

采用大型三维软件Solid Works建立发动机曲轴箱,基于ANSYS Workbench对曲轴箱进行模态分析和谐响应分析。自由模态分析中,得出了发动机曲轴箱前6阶固有频率及振型云图,曲轴箱的最低阶模态频率1709.8 Hz与发动机转子频率125 Hz不相等,故不会发生共振;对曲轴箱谐响应分析中,确定对被测面出现最大应力和最大位移时的频率为1 950 Hz,找出曲轴箱正常工作状态下结构振动剧烈的区域,为曲轴箱的测试分析和结构优化提供了理论依据,为研究曲轴箱的减震降噪技术提供了新思路和新方法。     

基于模态相关分析的发动机曲轴箱模型修正

以发动机曲轴箱为例,给出一种复杂结构有限元模型合理性验证的方法。采用锤击法测得曲轴箱的试验模态频率和固有振型,应用Ansys建立有限元模型并进行了计算模态分析,对试验模态和有限元模态进行模态相关分析,检验有限元模型的合理性。修正后的有限元模型,与实验的前5阶频率和振型基本吻合。     

摩托车发动机曲轴箱盖的模态分析

发动机是摩托车结构中产生噪声的主要部件,研究发动机曲轴箱盖的动力学特性对于噪声的研究与控制具有重要意义.文章利用Pm/E软件建立了左曲轴箱盖的实体模型,用有限元分析软件ANSYS对其进行了振动模态分析,为发动机左曲轴箱盖的进一步计算和设计提供了依据.     

微型空气压缩机组合式曲轴的扭振分析

双列立式微型往复空压机是目前新能源商用车气源的主流技术发展方向。在某机型的研发中发现,样机存在噪声、振动超标的问题,其中曲轴箱附近的噪声最大,峰值频率在1250Hz,为基频的整数倍。由于轴系的振动是曲轴箱振动和噪声的重要来源,有必要对该机型采用的组合式曲轴进行研究,判断其是否发生扭转共振。采用常惯量模型处理轴系往复质量产生的影响,考虑了轴系的装配体接触问题,建立了轴系扭振的计算分析模型。在考虑曲轴的转速和在曲轴箱中约束的基础之上,对轴系进行了静力分析,并以此为边界条件,提取了轴系的固有频率及模态振型。最后对使曲轴发生扭转振动的激励——切向力进行了谐波分析,并结合模态参数进一步判断得出：该压缩机的轴系在工作条件下不会发生扭转共振。     

某结构复杂曲轴箱的加工工艺设计及数控程序编制

曲轴箱零件作为箱体部件装配时的基准零件,对该机器的工作精度、使用性能和寿命都有直接的影响.本文首先论证了应用先进制造技术加工结构复杂曲轴箱的必要性,然后对某曲轴箱零件加工特点进行分析,设计出该曲轴箱的加工工艺路线.在此基础上,确定了加工刀具及切削用量.最后对该曲轴箱部分孔加工进行了相应的数控程序编制.实践表明:采用先进制造技术大大提高了曲轴箱的加工效率与产品的综合性能.     

发动机冷启动试验曲轴箱压力高问题分析

为了满足自身曲轴箱的密封功能、以及维持活塞环的密封特性,发动机曲轴箱压力需要始终维持在微负压状态。曲轴箱压力是由曲轴箱强制通风系统进行调节控制的,特别是在极寒环境下,该系统极易结冰堵塞,导致压力升高。同时发动机在极寒工况下需要顺利启动点火,为了验证发动机是否能满足极寒工况点火特性,我司开发的发动机需要完成“发动机冷启动试验”。本文分析的是冷启动试验中,出现曲轴箱压力高后,排查曲轴箱通风系统解决问题的方法。     

HXN5型内燃机车柴油机轴箱超压问题分析与预防措施

本文从HXN5型内燃机车柴油机曲轴箱相关零部件的工作条件、常见故障等多方面分析了曲轴箱超压问题的故障现象和故障原因,并提出了解决和预防曲轴箱超压的方法,有效避免了柴油机使用期间的曲轴箱超压事故的发生。     

16V265H型柴油机曲轴箱压力超限的原因探索及防控措施

HXN3机车采用的16V265H型柴油机,为保证曲轴箱内负压要求,加装了曲轴箱压力传感器来随时监测曲轴箱的实时压力值。增设了曲轴箱压力自动调整装置——引射装置来确保曲轴箱正常工作状态下的负压值。通过对日常机车运用和检修作业中发生的曲轴箱压力超限造成柴油机停机问题,查找产生故障的原因,制定相应的有效防控措施。     

6M发动机曲轴箱增开平衡孔后的有限元分析

为平衡某6M发动机曲轴箱内压力,故在其曲轴箱轴承座上增开两平衡孔;通过对曲轴箱开孔前后的三个工况下的有限元分析得到:加孔后曲轴箱应力和变形值与加孔前的曲轴箱相当,因此可以认为加孔后的曲轴箱的可靠性是可以得到保证的。     

寒冷天气下车用发动机曲轴箱通风系统故障分析

随着国家排放法规要求越来越严格,曲轴箱通风系统对整车排放的影响越来越大,曲轴箱通风系统已经成为车用发动机重要组成部分。本文介绍了车用发动机曲轴箱通风系统在寒冷天气下的故障模式及故障产生机理,通过对标及分析,提出了几种对应的解决措施,主要包括:合理的曲轴箱通风系统呼吸管布置、增强曲轴箱通风系统的保温措施及增加电加热装置。     

Effect of palm oil methyl ester and its emulsions on lubricant degradation and engine component wear

This paper presents the results of experimental work carried out to evaluate the effect of palm oil methyl ester also known as palm oil diesel (POD) and its emulsions, as alternative fuels, on unmodified indirect‐injection diesel engine wear and lubricant oil deterioration compared with ordinary diesel (OD). A constant 2500 rpm engine setting at half throttle was maintained throughout the wear debris and lubricant oil analysis period for 20 h for each fuel system. Samples of lubricant oil were collected through a one‐way valve connected to the crankcase sump at intervals of 4 h. The first sample was collected immediately after the engine had warmed up. The same lubricating oil, a conventional SAE 30, was used for all experiments. A multi‐element oil analyser was used to measure metal wear debris and lubricating oil additive depletion for the used lubricating oil. An ISL automatic houillon viscometer (ASTM D 445) and potentiometric titration (ASTM D 2896) were used to measure the viscosity and total base number, respectively. The lubricant oil analysis results for POD, OD, and their emulsions containing 10% water by volume were compared. Very promising results were obtained. The accumulation of metal wear debris in crankcase oil samples was lower with POD and its emulsion compared with the OD fuel. The addition of 10% water (by volume) to POD showed a promising tendency for wear resistance.     

基于振动噪声的柴油机油底壳结构优化研究

基于模态参数的动态特性,针对某型柴油机振动噪声超标问题,利用有限元软件ABAQUS的模态分析功能对主要噪声源油底壳的自由模态进行计算,从固有频率方面着手优化其结构。优化后的其固有频率大幅提高,经整机振动噪声测试,减振降噪效果明显,解决了振动噪声超标问题。     

Used crankcase oil as a cutting fluid

Used crankcase oil compares favorably with straight cutting oils in drilling operations, since it provides lower cutting forces and longer tool life.     

车用柴油机机体及油底壳的动态特性分析

采用脉冲激振模态试验和有限元模态分析对某车用柴油机机体和油底壳进行了模态分析,得到了其主要固有频率和模态,分析了主要激励源特征和结构响应特征,提出结构优化方向,为进一步的强迫振动和噪声分析奠定了基础.     

Flow uniformity in a multi-intake pump sump model

The head-capacity curves for pumps developed by the pump manufacturer are based on tests of a single pump operation in a semi-infinite basin with no close walls or floors and with no stray currents. Therefore, flow into the pump intake is with no vortices or swirling. However, pump station designers relying on these curves to define the operating conditions for the pump selected sometimes experience reductions of capacity and efficiency, as well as the increase of vibration and additional noise, which are caused by free air mixed with the pump inlet flow. Therefore, sump model test is necessary in order to examine the flow structure around pump intake. In this study, flow uniformity according to the flow distribution in the pump intake channel is examined to find out the cause of vortex occurrence in detail. A multi-intake pump sump model with 7 pump intakes and a single-intake pump sump model are adopted for the investigation. Furthermore, effectiveness of anti-submerged vortex device (AVD) for the suppression of the vortex occurrence in a single pump intake, as well as in a multi-intake pump sump model has been examined by the methods of experiment and numerical analysis. The results show that most high value of flow uniformity is found at the inlet of pump intakes #3 and 5 in the multi-intake pump sump with 7 pump intakes. Therefore, when the pump station is designed, the flow patterns at the upstream region of pump intake inlet in the forebay diffusing area should be to consider in detail because the unbalanced flow at the channel inlet region gives considerable influence on the vortex occurrence around bell-mouth. Strong submerged vortex can be successfully suppressed by AVD installation on the bottom of pump intake channel just below the bell mouth.     

新型摇摆活塞式无油润滑空气压缩机的研究

提出一种新型摇摆活塞式无油润滑空气压缩机,利用活塞摇摆运动时与气缸形成的侧隙构成进气通道,并利用曲轴箱作为压缩机的进气消声室。新机型摒弃了易损件进气簧片阀,拓展了进气消声器容积,与传统摇摆活塞机型相比无故障工作时数提高约119／6、噪声降低约5～6dB（A）。研究表明,气缸向压缩行程一侧适当偏置,同时辅以较大数值的曲柄连杆比λ,可以实现活塞侧隙进气,并能确保压缩行程时密封环对气缸的密封性,另外还可减小压缩机的体积;但是,为了缓解活塞对气缸的敲击,必须设置缓冲装置,而且需要强化连杆的散热和隔热,以减小连杆轴承的温升。     

便携式无油润滑空压机冷却系统布局探讨

对某便携式曲轴箱进气无油润滑空压机冷却系统的布局进行了探索,针对该机曲轴箱轴承座温度较高的弱点,采用让部分冷却风横渡扫掠曲轴箱的冷却方案,使轴承座的温度较之采用传统冷却方式时的温度下降了大约4℃,由此提高了压缩机主轴承的工作可靠性。     

Effects of macro-parameters on vibration and radiation noise for high speed wheel gear transmission in electric vehicles

Considering flexible shafts, a coupled dynamic model for the gear transmission system of wheel reducer used in electric vehicle was developed. By combining the acoustics finite element modal for housing in Virtual Lab and the coupled dynamic model for gear transmission system, a simulation method was proposed for the prediction of the radiation noise for the wheel reducer. Then, the effects of different macro geometry gear parameters including pressure angle and helical angle on the dynamic response and radiation noise were investigated under the rated working condition. Results show that the peak-peak value of the transmission error dramatically falls in the starting zone, followed by an upward trend with the increase of the pressure angle for the low speed stage gear pair. The minimum transmission error and vibration acceleration occur when the pressure angle is 17°. The increase of the pressure angle does not affect the sound pressure level at the field point obviously. The design case with 17° pressure angle shows the optimum radiation noise level, which is 4.41dB less than the original model. Compared to the pressure angle, the helix angle has a major influence on the transmission error, vibration acceleration and acoustic radiation noise. With the increase of the helix angle, the time-varying transmission error curve becomes more smooth with a lower peak-peak value. Besides, the increase of helix angle results in lowering the varying and fluctuating trend of both vibration acceleration and acoustic radiation noise. The design case with 24° helix angle shows the prime radiation noise level, which is 7 dB less than the original scheme.