柴油机发火顺序及排气管布置组合优化分析

郑茂勇^1,2，孙振宇^1,2，于淼淼^1,2，董卫涛^1,2，黄鹏^1,2

1.内燃机可靠性国家重点实验室，山东 潍坊  261061；2.潍柴动力股份有限公司，山东 潍坊  261061

摘要：以8缸直列双增压柴油机为研究对象，建立一维仿真模型，研究不同发火顺序及排气管布置组合对柴油机经济性、低速动力性、单缸均匀性的影响。计算结果表明：对于定压排气管，发火顺序对柴油机性能影响较小，仅通过优化发火顺序无法大幅度提高柴油机低速经济性和低速动力性；排气管布置和发火顺序组合优化对柴油机性能影响较大，可以在兼顾高速性能及单缸均匀性的前提下，大幅度提高柴油机低速经济性和低速动力性。

关键词：柴油机；发火顺序；排气管布置；低速动力性；单缸均匀性

The combination optimization of fire order andexhaust pipe layout on diesel engine

ZHENG Maoyong^1,2, SUN Zhenyu^1,2, YU Miaomiao^1,2,DONG Weitao^1,2, HUANG Peng^1,2

1.State Key Laboratory of Engine Reliability, Weifang 261061, China;2.Weichai Power Co., Ltd., Weifang 261061, China

Abstract：Based on an 8-cylinder in-line dual-turbocharged diesel engine, an one-dimensional simulation model is established to study the effects of fire order and exhaust pipe layout on fuel economy, low speed power performance and cylinder uniformity. The results indicate that the fire order has little effect on the diesel engine performance for the constant pressure exhaust pipe, and the low speed fuel economy and low speed power performance of the diesel engine cannot be greatly improved only by optimizing the fire order. The combined optimization of exhaust pipe layout and firing order has a great effect on the diesel engine performance, which can improve low speed economy and low speed power performance effectively on the premise of ensuring the high speed performance and the cylinder uniformity.

Keywords:diesel engine; fire order; exhaust pipe layout; low speed power performance; cylinder uniformity

内燃机活塞环-缸套摩擦学特性试验研究

葛畅，王福鑫，马旋^*，焦博文

哈尔滨工程大学动力与能源工程学院，黑龙江 哈尔滨  150001

摘要：以活塞环、缸套小样为试件，在Rtec MFT-5000型多功能摩擦磨损试验机上进行活塞环-缸套试件摩擦学特性模拟试验，研究富油润滑条件下，不同载荷、不同往复频率工况下7种不同表面结构试件的摩擦学性能。试验结果表明：缸套表面粗糙度并非越小、越光滑越好，不同的工况应匹配不同的粗糙度，粗糙度匹配合理可减小摩擦副的摩擦因数；不同表面织构对工况变化的响应不同，在适合的工况下合理的织构设计可以减小摩擦和摩擦力波动，不合理的织构设计使摩擦副的润滑情况变差。

关键词：活塞环；缸套；表面结构；摩擦学特性

Experimental study on tribological characteristics of piston ring and cylinder liner for internal combustion engine

GE Chang, WANG Fuxin, MA Xuan^*, JIAO Bowen

College of Power and Energy Engineering, Harbin Engineering University, Harbin 150001, China

Abstract：The tribological properties of piston ring-cylinder liner specimens are investigated on RTEC MFT-5000 multifunctional friction and wear testing machine. The tribological properties of seven different surface structures under oil-rich lubrication conditions with different loads and reciprocating frequencies are studied. The experimental results show that the smoother the surface roughness of the cylinder liner is not the better, and there are different roughness matching under different working conditions. The appropriate roughness matching can reduce the friction coefficient of the friction pair. Different surface structures have different responses to the change of working conditions. Reasonable texture design can reduce the friction and friction fluctuation under suitable working conditions, while unreasonable texture design will make the lubrication of friction pair worse.

Keywords: piston ring; cylinder liner; surface texture; tribological characteristics

举升式汽车加载制动检验台关键技术参数试验研究

刘元鹏¹，唐向臣^2*，崔江伟²，唐浩轩²

1.交通运输部公路科学研究院，北京  100088；2.山东新凌志检测技术有限公司，山东 济南  250014

摘要：通过台架试验法试验研究检测汽车制动性能，提出举升式汽车加载制动检验台的安置角及转鼓中心距、安装与举升高度等关键技术参数的指标和技术要求。研究结果表明：转鼓中心距的设计计算以承载重量、车轮直径、安置角为基本依据，对应额定载荷为100、130 kN的转鼓制动台，转鼓中心距分别为450、470 mm，误差均为±10 mm；转鼓加载制动台安装时，转鼓上母线距地水平面高度应为40~45 mm，加载举升高度距地水平面不小于200 mm。该研究可为举升式汽车加载制动台的设计、生产、使用和产品检验提供参考。

关键词：加载制动检测；安置角；转鼓中心距；举升高度

Experimental study on key technical parameters of lifting typeof automobile loading brake test bench

LIU Yuanpeng¹, TANG Xiangchen^2*, CUI Jiangwei², TANG Haoxuan²

1.Research Institute of Highway Ministry of Transport,Beijing 100088，China;2.Shandong Xinlingzhi Detection Technology Co., Ltd.,Jinan 250014，China

Abstract：The automobile braking performance is tested by bench test, and the requirements for key parameters of the lift-mode vehicle load braking test bench including formed angle, roller central distance and height of install and lift, etc are proposed. The results indicate that the design of the roller central distance should be based on the load capacity,wheel diameter and formed angle.For the roller brake bench with rated load capacity of 100 N and 130 N, the roller central distance should be 450 mm and 470 mm with ±10 mm error.When installing the bench, the suitable height from the ground to the auxiliary roller is 40-45 mm, and the loading lift height from the ground should be no less than 200 mm.The study can provide reference for the design,production,use and product ispection of lift-mode vehicle load braking test bench.

Keywords:load brake detection; formed angle; roller center distance; lifting height

重型发动机整车热平衡试验分析

李寒寒，董方龙，刘井年，任利东，成敬敏

潍柴动力股份有限公司，山东 潍坊  261061

摘要：为提高整车热平衡能力，对某重型发动机风扇及冷却系统进行研究，分析风扇、冷却模块及整车布置对热平衡的影响，提出一种评估风扇性能差异的方法，通过优化改进风扇结构及分析整车风路布置的合理性，提高整车的高温适应能力。结果表明：在已有的整车热平衡试验数据基础上，通过理论分析及仿真计算方法评估其它工况点或其它风扇配置的整车热平衡结果，可将误差控制在4 ℃以内；优化风扇结构可以改善整车热平衡。该分析可以为研究整车冷却系统提供参考。

关键词：重型发动机；风扇；冷却模块；整车热平衡

Analysis of heat balance experimental for vehicle of heavy engine

LI Hanhan, DONG Fanglong, LIU Jingnian, REN Lidong, CHENG Jingmin

Weichai Power Co., Ltd., Weifang 261000,China

Abstract：In order to improve the vehicle thermal equilibrium ability, the fan and cooling system of a heavy duty engine are studied,the effect of the fan, cooling module and the whole vehicle arrangement on heat balance have been analyzed,and a method of fan performance difference evaluation has been developed. The structure of the fan is improved, and the air path arrangement of the vehicle has been analyzed,the high temperature adaptability of the whole vechicle is improved. The results show that based on the existing thermal balance of the vehicle, the theoretical analysis and simulation of thermal balance at the other working conditions can predict the results in which the error could be controlled within 4℃;optimizing the fan structure can improve the heat balance of the whole vehicle.The analysis can provide reference for the research of vehicle cooling system.

Keywords:heavy duty engine; fan; cooling module;vehicle thermal balance

基于模型的柴油机排放预测技术

钟祥麟¹，于全顺¹，高忠明¹，陈旭²

1.中国汽车技术研究中心有限公司，天津  300300；2.山东大学能源与动力工程学院，山东 济南  250061

摘要：为实现柴油机排放预测，利用试验设计（design of experiment，DoE）试验获取满足柴油机工作范围的稳态试验数据，利用反向传播（back propagation，BP）神经网络搭建柴油机气缸模型，使用GT-Power软件搭建柴油机的进排气系统模型，将两者耦合搭建柴油机整机模型，并通过试验验证模型在稳态及瞬态工况下的预测精度。结果表明：稳态工况下模型的NOx排放预测相对误差为4.1%，瞬态循环工况下模型的NO_x排放预测相对误差为1.2%；该模型可以较准确地预测柴油机的排放。

关键词：柴油机；BP神经网络；GT-Power；NO_x排放预测；瞬态循环

Diesel engine emission prediction technology based on model

ZHONG Xianglin¹，YU Quanshun¹，GAO Zhongming¹，CHEN Xu²

1.China Automotive Technology and Research Center Co., Ltd., Tianjin 300300,China;

2. School of Energy and Power Engineering, Shandong University,Jinan 250061,China

Abstract：In order to realize the emission prediction of diesel engine, the design of experiment (DoE) test is used to obtain the steady-state test data meeting the working range of diesel engine, the cylinder model of diesel engine is built through back propagation (BP) neural network, the intake and exhaust system model of diesel engine is built by GT-Power software, and the two are coupled to build the whole diesel engine model. The prediction accuracy of the model under steady-state and transient conditions is verified by experiments. The results show that the NO_x emission prediction error of the model is 4.1% under steady-state conditions and 1.2% under transient cycle conditions. The model can accurately predict the emission of diesel engine.

Keywords:diesel engine;BP neural network;NO_xemission prediction;transient cycle

中型柴油机排气制动性能仿真优化

刘俊龙^1,2，陈国强^1,2，张洋洋^1,2，韩美莹^1,2

1.内燃机可靠性国家重点实验室，山东 潍坊  261061；2.潍柴动力股份有限公司，山东 潍坊  261061

摘要：为优化柴油机的辅助制动性能，以某中型柴油机为研究对象，采用GT-Power软件搭建一维热力学仿真模型，分析制动型线和相位变化对发动机制动性能的影响，研究压缩释放（compression release，CR）制动排气门开启相位、排气再循环制动（brake gas recirculation，BGR）排气门开启相位、开启包角以及排气复位等参数变化对发动机制动升功率、进气质量流量和爆压的影响规律。结果表明：同时采用CR制动与BGR可使制动升功率增加约20%；存在CR制动排气门开启最佳相位使制动升功率最大；采用排气门开启复位时制动升功率增加。基于此规律对制动型线优化，优化后的制动型线可使发动机的制动升功率提高5.1 kW/L。

关键词：柴油机；压缩释放；排气再循环；制动性能

Simulation and optimization of exhaust brakingperformance for a medium-sized diesel engine

LIU Junlong^1,2, CHEN Guoqiang^1,2, ZHANG Yangyang^1,2, HAN Meiying^1,2

1.State Key Laboratory of Engine Reliability,Weifang 261061,China;2.Weichai Power Co., Ltd., Weifang 261061,China

Abstract：To improve the braking performance of diesel engine, a medium-sized diesel engine is employed to investigate the influences of the brake lines and their phase on the braking performance of the engine. The effects of compression release, brake gas recirculation and exhaust valve closing timings-with and without reset are simulated by GT-Power. It could be found that compression release braking as well as exhaust recirculation braking can increase braking power by about 20%, and there is an optimal exhaust valve opening phase angle to maximize braking power. The use of exhaust valve opening reset will also increase the braking power. Based on the conclusions, the original brake line is further optimized and thus the brake power increased by 5.1 kW/L.

Keywords:diesel engine；compression release；exhaust gas recirculation；braking performance

轻型柴油机活塞裙部型线对磨损的影响

郭金宝^1,2，陈丽^1,2*，邢小兵¹，周璐璐¹，韩立国^1,2

1．滨州渤海活塞有限公司，山东 滨州  256602；2.山东省发动机活塞摩擦副重点实验室，山东 滨州  256602

摘要：以某轻型柴油机活塞为研究对象，基于型线设计理论，设计4种活塞裙部型线方案。利用活塞动力学分析软件进行分析计算，研究活塞裙部型线对活塞二阶运动和裙部摩擦磨损的影响，并对L4方案的活塞进行耐久试验。结果表明：改变活塞裙部型线可以较好地改善裙部润滑；与L1方案相比，L4方案的活塞裙部最大压力降低了约25.3%，裙部最大累积磨损载荷降低了约32.1%，有效地改善了裙部摩擦磨损问题；耐久试验验证了仿真分析结果的正确性。该分析可以为轻型柴油机活塞裙部摩擦磨损提供借鉴。

关键词：活塞；裙部型线；动力学分析；磨损

Influence of piston skirt profile on wear of light vehicle diesel

GUO Jinbao^1,2, CHEN Li^1,2*, XING Xiaobing¹, ZHOU Lulu¹, HAN Liguo^1,2

1.Binzhou Bohai Piston Co.,Ltd.,Binzhou 256602,China;2.Shandong Province Key Laboratory of Engine Piston Cylinder Kits,Binzhou 256602,China

Abstract：Taking the piston of a light vehicle diesel engine as the research object,four types of piston skirt profile are carried out based on the profile design theory. Using piston dynamic analysis software to analyze and calculate the influence of skirt profiles on piston second motion and skirt wear,and the endurance test is carried out on the engine equipped with the piston of L4 scheme. The results show that changing the skirt profile, the skirt lubrication is improved significantly. Compared with scheme L1, the maximum skirt pressure is reduced 25.3% and the maximum skirt wear load is reduced 32.1% of scheme L4 piston skirt, which effectively solves the skirt friction and wear. The accuracy of dynamic simulation is verified after endurance test. This dynamic analysis can provide a guidance for light vehicle diesel engine piston skirt friction and wear.

Keywords:piston; skirt profile; dynamic analysis; wear

柴油机活塞积碳控制技术

朱杨^1,2，王洪山^1,2，许成^1,2，傅晓磊^1,2

1.内燃机可靠性国家重点实验室，山东 潍坊  261061；2.潍柴动力股份有限公司，山东 潍坊  261061

摘要：分析导致柴油机活塞组积碳的原因，利用预测仿真分析技术，提出活塞润滑油积碳控制技术。结果表明：缸套温度高、活塞温度高和活塞环运动泵油是润滑油在活塞与活塞环摩擦副积碳形成并累积的原因；控制缸套温度、活塞环槽温度及活塞环运动可以避免形成积碳；动力学仿真技术可以精确预测活塞环的运动，为活塞环优化设计提供有效参考。

关键词：活塞；活塞环；积碳；温度；动力学仿真

Carbon deposit control technology of diesel engine piston

ZHU Yang^1,2, WANG Hongshan^1,2, XU Cheng^1,2, FU Xiaolei^1,2

1. State Key Laboratory of Engine Reliability, Weifang 261061,China;2.Weichai Power Co., Ltd., Weifang 261061,China

Abstract：To avoid diesel engine piston carbon deposit, the cause of carbon deposit is analyzed, the carbon depositcontrol technology of piston oil is proposed. The results show that the high temperature of cylinder liner，piston，and oil pumping caused by piston ring movement are the main reason for oil-related carbon accumulation in the piston and piston ring friction pair. Carbon formation can be avoided by controlling the temperature of cylinder liner, piston ring groove and piston ring movement. Piston dynamics simulation technology can accurately predict the movement of piston ring and provide an effective method for optimal design of piston ring.

Keywords:piston; piston ring;carbon deposit; temperature;dynamic simulation

基于大涡模拟的煤粉湍流燃烧研究

桂莹¹，黄照坤²，李琳红³

1.贵州工业职业技术学院，贵州 贵阳  550000；2.贵州乌江水电开发有限责任公司，贵州 贵阳  550000；

3.青岛市城市规划设计研究院，山东 青岛  266022

摘要：基于开源计算流体力学（computational fluid dynamics, CFD）计算程序包OpenFOAM模拟煤粉燃烧特性，运用大涡模拟（large eddy simulation, LES）方法模拟炉内燃烧情况，研究煤粉颗粒直径对火焰特性的影响，通过对比分析模拟结果和试验数据，验证LES及所用模型对气-固两相煤粉湍流射流燃烧模拟的有效性。研究表明：细煤粉燃烧的高温区域更广，火焰中心离喷嘴出口更近，局部温度更高，燃烧更加充分；建立的湍流及燃烧模型可靠有效，可为锅炉、内燃机及其他动力装置中燃烧流动的稳定性研究及系统优化设计提供理论依据，对揭示其他复杂的燃烧现象也有一定的参考价值。

关键词：煤粉燃烧；湍流；LES；CFD

Large eddy simulation of pulverized coal turbulent combustion

GUI Ying¹, HUANG Zhaokun², LI Linhong³

1. Guizhou Industry Polytechnic College, Guiyang 550000, China;2. Guizhou Wujiang Hydropower Development Co., Ltd., Guiyang 550000, China;

3. Qingdao Urban Planning & Design Research Institute, Qingdao 266071, China

Abstract：An open-source computational fluid dynamics (CFD) code-Open FOAM (open field operation and manipulation) is applied to predict the combustion characteristics of pulverized coal with large eddy simulation (LES) method. The effect of coal particle diameters on the flame characteristics is also investigated. The simulation is validated by the experimental data of reference. It has been observed that the region of high temperature is wider, the flame center is closer to the nozzle exit, and the local temperature is higher for smaller particles. The simulation results show that the turbulence and combustion models are reliable and effective. The researching results can provide theoretical basis for the stability and system optimization design of combustion flow and system optimization design in boilers, internal combustion engines and other power plants, and provide reference for other more complex combustion phenomenon.

Keywords:pulverized coal combustion; turbulence; large eddy simulation; CFD

国六轻型量产车辆评估测试方法分析

姜山，高祥，姜晓龙，张新宇

上海汽车集团股份有限公司商用车技术中心，上海  200438

摘要：针对轻型车国六排放标准中新增车载诊断（on board diagnostics，OBD）系统认证项目——量产车辆评估（production vehicle evaluation,PVE）测试，介绍PVE测试方法及相关要求，分析OBD故障码分类原则和诊断原理，介绍不同故障类别的测试实例，分析PVE J2测试方法及难点，总结故障模拟方法。分析结果表明：熟悉故障诊断原理是故障码分类的基础，根据传感器和执行器的工作原理和信号类别合理选择故障植入所需设备，结合故障诊断所需边界条件，完成测试。该分析可为行业企业进行PVE测试提供参考。

关键词：OBD；PVE；模拟故障

Analysis on the test method of the CHINA 6 lightproduction vehicle evaluation

JIANG Shan, GAO Xiang, JIANG Xiaolong, ZHANG Xinyu

Commercial Vehicle Technology Center, Shanghai Automotive Group Co.,Ltd., Shanghai 200438, China

Abstract：In view of the newly added on board diagnostics (OBD) system certification in the CHINA 6 emission standards for production vehicle evaluation (PVE) testing, the PVE test method and related requirements are introduced, and the OBD fault code classification principle as well as diagnosis principles are analyzed. The test examples of different fault categories is introduced, PVE J2 test methods and difficulties are analyzed and the fault simulation methods are summarized. The analysis results show that familiarity with the principle of fault diagnosis is the basis of fault code classification. According to the working principle and signal category of sensors and actuators, the equipment required for fault implantation is reasonably selected, and the boundary conditions required for fault diagnosis are combined to complete the test one by one. These works can provide reference for industry enterprises to conduct PVE testing.

Keywords:OBD; PVE; failure simulation

汽车发动机机舱阻力系数影响因素分析

曾超^1,2，李杰^1,2，钟绵远^1,2，刘德柱^1,2

1.内燃机可靠性国家重点实验室，山东 潍坊  261061；2.潍柴动力股份有限公司，山东 潍坊  261061

摘要：以某款牵引车为例，基于质量、动量、能量守恒方程建立机舱内流场仿真模型，采用一维-三维耦合的方法对机舱内流场进行仿真，经试验验证仿真模型正确可行。研究不同发动机、冷凝器前布置方式、风扇与散热器匹配、驾驶室底舱到发动机摇臂罩距离以及驾驶室到车厢的距离对机舱阻力因数（built-in resistance，BiR）的影响。结果表明，风扇与散热器的匹配关系对BiR影响最大。研究成果可为一维热管理仿真确定BiR提供参考。

关键词：BiR；散热器风量；耦合；流场仿真

Analysis of on the influencing factors of the built-in resistance ofautomobile engine compartment

ZENG Chao^1,2，LI Jie^1,2，ZHONG Mianyuan^1,2，LIU Dezhu^1,2

1. State Key Laboratory of Engine Reliability, Weifang 261061,China;2. Weichai Power Co.,Ltd., Weifang 261061,China

Abstract：Taken a tractor as an example, 1D & 3D coupled simulation method based on mass, momentum and energy conservation are used to model flow field in engine compartment, which is validated by experiments. Different engine, arrangement in front of condenser, fan and radiator matching relations, distance between floor and the engine rocker cover, distance between the cab and carriage are simulated in order to study their influence on engine builtin resistance (BiR). It is found that the matching of fan and radiator is the main factor for BiR. This conclusion could be helpful for 1D thermal management simulation and the calculation of BiR.

Keywords: built-in resistance; radiator air volume; coupling; flow field simulation

增压器旁通阀轴焊接疲劳分析与寿命评估

马仙龙¹，张正华²

1.无锡康明斯涡轮增压技术有限公司，江苏 无锡  214045;2.河南交通职业技术学院，河南 郑州  450005

摘要：针对某发动机耐久试验中增压器旁通阀轴与阀片臂焊接失效问题，采用电子显微镜扫描故障旁通阀断口，发现旁通阀轴焊接熔池内有裂纹，试验验证裂纹扩展具有明显的方向性，与载荷的施力方向强相关，判定焊接失效为高温环境下的机械疲劳断裂。从焊接工艺上改善焊接质量，消除和降低应力集中，降低焊接失效风险。通过对比台架、路试试验与旁通阀轴焊接疲劳耐久加速试验的疲劳累计损伤，完成改进焊接质量样件的寿命风险评估，避免台架、路试耐久试验可能造成的时间与成本浪费。

关键词：旁通阀轴；焊接；疲劳失效

Fatigue failure analysis and life assessment of turbocharger wastegate shaft welding

MA Xianlong¹, ZHANG Zhenghua²

1.Wuxi Cummins Turbocharger Technology Co., Ltd., Wuxi 214045, China;2.Henan College of Transportation, Zhengzhou 450005, China

Abstract：The fatigue failure happened on the turbocharger wastegate shaft and valve welding interface in engine endurance test, it was observed the shaft and welding pool with initial micro cracks by SEM analysis. It is verified that the crack propagation has obvious directionality which is strongly related to the force direction by test. It could be inferred that the welding failure is mechanical fatigue under high temperature. The welding quality is improved by welding process optimization, and stress concentration is eliminated. The risk assessment for improved welding samples fatigue life is carried out by calculating the welding cumulative fatigue damage of engine test and road test as well as the wastegate shaft welding fatigue accelerate test. This method can reduce the cost of engine test and road test.

Keywords:wastegate shaft; welding; fatigue failure

发电机单向超越离合皮带轮的性能仿真与试验研究

徐贤发^1,2,卜祥玮^1,2,马灵童^1,2,王文平^1,2,朱健^1,2,周竹杰^1,2

1.内燃机可靠性国家重点实验室，山东 潍坊  261061；2.潍柴动力股份有限公司发动机研究院，山东 潍坊  261061

摘要：分析发动机前端轮系张紧轮故障原因，提出在发电机上应用单向超越离合皮带轮的改进措施，对改进后的前端轮系进行功能性、可靠性、耐久性试验和仿真分析。结果表明：发动机超越离合皮带轮具有较高可靠性，可以有效解决张紧轮摆角大导致的张紧器阻尼磨损故障，改善前端轮系的运行状态，提高噪声、振动与声振粗糙度（noise, vibration, harshness，NVH）性能。本文中单向超越离合皮带轮的研发方案不仅可用于解决前端轮系的故障，也可作为解决因转速波动导致的其他传动系统故障的参政。

关键词：前端轮系；转速波动；单向超越；可靠性；NVH

Performance simulation and experimental research onone-way clutch overrunning pulley of generator

XU Xianfa^1,2, BU Xiangwei^1,2, MA Lingtong^1,2, WANG Wenping^1,2,ZHU Jian^1,2, ZHOU Zhujie^1,2

1.State Key Laboratory of Engine Reliability, Weifang 261061, China;2.R&D Center，Weichai Power Co., Ltd., Weifang 261061, China

Abstract：The failure of the tensioner in the front end accessory drive (FEAD) is analyzed, the one-way overrunning clutch pulley on the generator is proposed for improvement. The reliability and durability tests and simulation analysis of the improved FEAD are carried out. The results show that the one-way overrunning clutch pulley has high reliability, which can effectively solve the tensioner damping block’s wear failure caused by the large swing angle of the tensioner. The running performance of FEAD and NVH performance are also improved. The research and development scheme of the one-way overrunning clutch pulley, can not only be used for the trouble shooting of the FEAD, but also provide a reference for solving other transmission system failures caused by speed fluctuation.

Keywords:FEAD; speed fluctuation; one-way clutch; reliability; NVH

排气系统热端支架低周疲劳开裂分析与优化

黄政^1,2，李云涛¹，蓝军¹，俞小莉²，杨万里¹，王瑞平¹

1.宁波吉利罗佑发动机零部件有限公司，浙江 宁波  315336；2.浙江大学工程师学院，浙江 杭州  310058

摘要：为解决发动机在耐久试验过程出现的排气系统热端支架开裂故障，采用流-固耦合与低周疲劳分析相结合的方法分析故障原因，确定在冷热交替情况下，增压器涡壳反复热膨胀及收缩，不断拉拽和挤压增压器支架，形成热应变集中并不断累积，达到低周疲劳寿命极限，出现开裂。对支架进行优化，减小支架在开裂处温度梯度及刚度梯度并使其均匀过渡。优化后支架对应原开裂处的等效塑性应变降低到0.1%，消除热应变，并通过耐久试验验证。

关键词：热端支架；开裂；低周疲劳；塑性应变

Low cycle fatigue crack analysis of hot end bracket ofexhaust manifold and its optimization

HUANG Zheng^1,2, LI Yuntao¹, LAN Jun¹,YU Xiaoli², YANG Wangli¹, WANG Ruiping¹

1.Ningbo Geely Royal Engine Component Co., Ltd.，Ningbo 315336, China;2.Polytechnic Institute，Zhejiang University, Hangzhou 310058, China

Abstract：In order to solve the cracking fault of the hot end support of the exhaust system during the durability development of a engine, the method of combining fluid-structure coupling and low cycle fatigue analysis is used. It is found that under the condition of alternating cold and heat, the turbocharger volute expands and contracts repeatedly, and constantly pulls and squeezes the supercharger support. Thus the thermal strain is concentrated and accumulated until it reaches the low cycle fatigue life limit and cracks appear. The optimization is carried out to reduce the temperature gradient and uniform stiffness transition of the support at the crack. After optimization, the equivalent plastic strain of the support corresponding to the original crack is reduced to 0.001, the thermal strain is eliminated, and finally verified by the durability test.

Keywords:hot end bracket; crack; low cycle fatigue; plastic strain

低温环境下低速工况对汽油机机油稀释的影响

任全水，马传京，朱云峰，孙程龙，田志松

宁波吉利罗佑发动机零部件有限公司，浙江 宁波  315336

摘要：针对汽油机在北方地区冬季特定工况常发生的机油稀释问题，分析机油稀释的危害及产生原因，研究低温环境低速工况对汽油机机油稀释的影响。研究发现，汽油机在低温环境、低速工况运行时，机油稀释的主要影响因素为燃油湿壁和燃油蒸发速度。选择低温挪车和短距离行驶工况，设计试验方法和流程，在冬季漠河汽车试验场进行低速工况机油稀释试验验证。试验结果表明：经过64个挪车工况，车辆行驶3.2 km后，最大机油稀释率为11.4%；经过20个短距离行驶工况，车辆行驶100 km后，最大机油稀释率为7.8%。研究结果可为汽油机在低温环境中的正常使用提供参考。

关键词：汽油机；低温环境；低速工况；机油稀释

Influence of low-speed operating condition in low-temperatureenvironment on gasoline engine oil dilution

REN Quanshui, MA Chuanjing, ZHU Yunfeng, SUN Chenglong, TIAN Zhisong

Ningbo Geely Royal Engine Components Co., Ltd., Ningbo 315000,China

Abstract：Aiming at the problem of oil dilution of gasoline engine under specific working conditions in North China in winter, the harm and causes of oil dilution are analyzed, and the influence of low-temperature environment and low-speed working conditions on oil dilution of gasoline engine is studied. Low-temperature moving and short-distance driving conditions are selected to design the test process which is used for test verification of oil dilution under low-speed conditions in Mohe automobile test site in winter. The results show that the maximum engine oil dilution rate is 11.4% after 64 moving conditions and driving for 3.2 km. After 20 short-distance driving conditions and 100 km driving, the maximum oil dilution rate is 7.8%. The research results can provide valuable reference for the normal use of gasoline engine in low temperature environment.

Keywords:gasoline engine; low-temperature environment; low-speed operating condition; oil dilution

柴油机活塞熔顶失效分析

吴士军^1,2，叶飞^1,2，刘斌^1,2，岳永丽^1,3，刘玲^1,2

1.内燃机可靠性国家重点实验室，山东 潍坊  261061；2.潍柴动力扬州柴油机有限责任公司，江苏 扬州  225009；

3.潍柴动力股份有限公司，山东 潍坊  261061

摘要：为解决某轻型柴油机在开发试验过程中出现的活塞熔顶故障，采用故障树法分析可能导致故障的原因，分别通过试验、物理检测、标定逻辑分析等方法对各因素进行分析与排除，确定导致活塞熔顶故障的原因为：凸轮轴信号缺失触发单曲轴信号降级起动，倒拖起动转速过高造成电子控制单元试喷射功能误判，导致异常燃烧、产生高温熔顶。采取优化起动方式、设置关联报警等措施，耐久试验表明活塞熔顶故障不再发生。

关键词：熔顶；故障树法；单曲轴信号；试喷射

Failure analysis of diesel engine piston top melting

WU Shijun^1,2, YE Fei^1,2, LIU Bin^1,2, YUE Yongli^1,3, LIU Ling^1,2

1.State Key Laboratory of Engine Reliability, Weifang 261061, China;2. Weichai Power Yangzhou Diesel Engine Co., Ltd., Yangzhou 225009, China;

3. Weichai Power Co., Ltd., Weifang 261061, China

Abstract：In order to solve the piston top melting fault of a light diesel engine in the development and test process, the fault tree is used to list the factors that may cause the fault, and experiment, physical detection, calibration logic analysis, etc., are used to analyze and eliminate the factors. It is determined that the cause of the piston top melting failure is that the lack of camshaft signal triggers the degraded start by single crankshaft signal, and the excessively high reverse starting speed will cause the ECU misjudgment of the test injection function. Then abnormal combustion and hightemperature molten roof happened. In order to avoid the recurrence of this fault, by optimizing the starting method and setting the associated alarms, the occurrence of the failure of the piston top molting is effectively avoided.

Keywords:melt top; fault tree; single crankshaft signal; test injection

柴油机机油压力低故障分析及改进

王权¹，李峰刚²，王锋¹，汪剑¹

1.中国重汽集团济南动力有限公司发动机制造公司，山东 济南  250220；2.滨州渤海活塞有限公司，山东 滨州  256602

摘要：分析导致柴油机机油压力低的原因，通过对摇臂系统的实际观测和建模研究摇臂油孔对机油压力的影响，并进行台架试验验证。结果表明：摇臂衬套安装角度偏小是导致机油压力降低的主要原因。改进压装机工装并设计摇臂衬套安装定位槽检查装置，实际应用表明，改进工装和使用定位槽检查装置可以有效保证衬套安装角度，解决机油压力低故障。

关键词：柴油机;摇臂油孔；衬套；机油压力

Fault analysis of low oil pressure in diesel engine and its improvement

WANG Quan¹, LI Fenggang², WANG Feng¹, WANG Jian¹

1. Engine Manufacturing Division, SinoTruk Jinan Power Co., Ltd., Jinan 250220, China；2.Binzhou Bohai Piston Co.,Ltd., Binzhou 256602,China

Abstract：The causes of low oil pressure of diesel engine are analyzed,the effect of oil hole in rocker arm on oil pressure is analyzed through observation and modeling, which is further verified by bench test. The results show that the small mounting angle of rocker arm bushing is the main reason for oil pressure reduction. The design of rocker arm bushing installation is improved, and a positioning groove inspection device is applied. Practical application shows that the modified device can effectively ensure the bushing installation angle and solve the problem of low oil pressure.

Keywords:diesel engine; oil hole of rocker arm; bushing; oil pressure

收获机液压行走系统噪声分析及改进

张新众^1,2，丁保安^1,2，张安安^1,2,杨铭^1,2

1.内燃机可靠性国家重点实验室，山东 潍坊  261061；2.潍柴动力股份有限公司，山东 潍坊  261061

摘要：采用仿真和振动噪声测试相结合的方法，解决收获机液压行走系统的结构噪声问题。采用力锤法对收获机行走系统进行模态测试，用模态参数频域法识别液压行走系统的固有频率、阻尼比和振型，确定噪声产生原因为：动力输出激励与系统模态重合，导致系统共振产生噪声；发动机输出端转速波动大，导致系统内部产生敲击噪声。针对振动噪声，加强行走系统和车架的刚度，使液压行走系统模态由23.5 Hz提升到51.2 Hz，避开发动机低转速下旋转频率的激励；针对内部敲击噪声，增加发动机输出后端转动惯量，怠速工况（750 r/min）时，整车转速波动由70 r/min减小至50 r/min。经测试，采取上述优化措施后，收获机液压行走系统噪声降低了5.3 dB，降噪效果明显。

关键词：收获机；液压泵；模态分析；转速波动

Noise analysis of hydraulic walking system ofharvester and its improvement

ZHANG Xinzhong^1,2, DING Baoan^1,2, ZHANG An′an^1,2, YANG Ming^1,2

1.State Key Laboratory of Engine Reliability, Weifang 261061, China;2.Weichai Power Co., Ltd., Weifang 261061, China

Abstract：The problem of structural noise of hydraulic walking system of harvester is solved by combining simulation theory with vibration and noise test. The modal test of the harvester traveling system is carried out by the force hammer method, and the natural frequency, damping ratio and vibration mode of the hydraulic walking system are identified by the modal parameter frequency domain method. It is determined that the causes of noise are as follows: the local mode of the system itself is not fully considered in the early stage of structural design, so that the power output excitation coincides with the system mode, resulting in system resonance and noise; The engine output dynamic balance becomes worse due to unreasonable subsequent matching, amplifying the speed fluctuation at the output end, resulting in knocking noise inside the system. Strengthen the stiffness of the traveling system and the frame to increase the mode of the hydraulic walking system from 23.5 Hz to 51.2 Hz to avoid the excitation of the rotation frequency at low engine speed. At the idle speed (750 r/min), the rotation speed fluctuation of the vehicle is optimized from 70 r/min to 50 r/min by increasing the moment of inertia at the rear end of engine output. By the above optimization, the noise of the hydraulic walking system of the harvester is reduced to 90.2 dB, and the noise is reduced effectively.

Keywords:harvester; hydraulic pump; modal analysis; speed fluctuation