共查询到19条相似文献,搜索用时 937 毫秒
1.
2.
3.
4.
5.
某发动机在台架冷热冲击试验中多次发生气缸垫外漏冷却液问题,在同步进行的道路试验中也出现同样问题。为查明原因并加以改善,使用有限元方法搭建了发动机整机网格模型,分别将仿真和试验的温度场和冷却液压力流量等作为边界条件,进行了气缸垫密封性能的动态仿真。为验证仿真结果的准确性,使用微型高精度位移传感器进行了预定位置的缸体缸盖间隙测试。结果表明:(1)在瞬态工况过程中,发动机缸体缸盖的间隙大部分时间低于常温停机状态,但在发动机快速进入大负荷而冷却液温度仍在上升时,间隙逐渐拉大并高于常温状态,此工况下发生发动机冷却液渗漏;(2)通过有限元方法建模和仿真计算气缸垫密封线压力,并使用实测温度和气缸垫特性作为边界,计算结果准确,可以有效评定气缸垫的密封性能;(3)首次采用安装小型位移传感器的方法准确测量了发动机动态工况中缸体缸盖的间隙,可以与仿真结合使用,能够准确找到发动机气缸垫外渗漏冷却液的工况和位置,明确了气缸垫外渗漏冷却液的解决方向。(4)发动机气缸垫功能层结构和层数直接影响密封性能,尤其是缸体缸盖间隙变大工况的密封性能。 相似文献
6.
7.
1.冷却液的种类(1)挥发性冷却液:含醇90%左右,冰点低,比水蒸发快,在补充冷却水时必须同时补充冷却液原液。(2)半挥发性冷却液:以甲醇或乙二醇为主要成分,性能中等,比挥发性冷却液蒸发得慢。(3)非挥发性冷却液:含乙二醇75%以上,冰点不很低,沸点高。尤其适用于重负荷机器或山区的环境,是目前市场的主要产品。 相似文献
8.
9.
10.
11.
T.‐C. Jao S. Li Kenji Yatsunami Shiahn J. Chen Aladar A. Csontos James M. Howe 《Lubrication Science》2004,16(2):111-126
The hardness of various types of soot produced by heavy‐ and light‐duty diesel engines of European, Japanese, and North American designs was measured by low‐loss electron energy‐loss spectroscopy (EELS). No clear general trend can be established that shows heavy‐duty diesel engine soot is necessarily harder than light‐duty diesel engine soot. The variation in hardness among individual soot particles produced by the same diesel engine can be as large as differences between the hardest soot particles produced by heavy‐duty diesel engines and the softest soot particles produced by light‐duty diesel engines. There are heavy‐duty diesel engines that can produce soot that is softer than that produced by some light‐duty diesel engines and vice versa. Nevertheless, the hardness of all types of soot studied is close to the range of hardness of metal engine parts. Thus, the results indicate that soot is hard enough to abrade some metal engine parts. 相似文献
12.
13.
针对重载货车在长大下坡路段行驶事故频发的问题,为减轻行车制动器工作负荷,采用理论与试验相结合的方法,该文建立了排气制动、电涡流缓速器制动的数学模型,研究重载货车在长大下坡行驶的持续制动特性,得出持续制动力矩与发动机转速的关系,为研究制动鼓温升模型以解决制动器热衰退问题奠定了基础。 相似文献
14.
Cha-Lee Myung Ahyun Ko Juwon Kim Kwanhee Choi Sangil Kwon Simsoo Park 《Journal of Mechanical Science and Technology》2013,27(12):3893-3902
This study compares the engine operating behavior and regulated gaseous emissions characteristics between the reference European cycles (ESC/ETC) and the worldwide harmonized driving cycles (WHSC/WHTC), which will be applied in the Euro VI heavy-duty diesel engine emissions regulations, for the diesel particulate filter (DPF) equipped Mercedes 12 L diesel engine. The speed and load distribution for two additional representative harmonized cycles which cover a more realistic operating range for a heavy duty engine were established to verify the engine performance over wide range of the cycle work, fuel consumption, and exhaust system temperature as well as engine coolant temperature for repeated validation tests. The WHTC, including an additional test with cold start and transient operation before the hot start, had a substantial influence on the THC, CO, NOx, and PM exhaust emissions levels because of the engine heat-up time and temperature rising characteristics of aftertreatment device. Moreover, the different engine operating conditions of the WHSC influenced on the specific engine performance and gaseous emissions behavior unlike those of the ESC. Finally, the statistical analysis results through repeated tests validated the stationary and transient cycles running at the fully warm-up condition, however, those of WHTC were closely dependent on the inclusion of cold start condition or aggressive acceleration gradient of engine speed and load trace. 相似文献
15.
16.
随着我国在基础设施和重点建设项目上的投入加大,重型载货车在市场上的需求量急剧上升,重型变速箱的需求也随之增加。为了适应市场需求,我公司开发出了DC7J100T七档变速箱,它的额定输入扭矩为100kgm,可匹配2lO~260Ps的发动机,供重载汽车、自卸车、牵引车及其它工程车使用。 相似文献
17.
This is a study of soot from a heavy duty diesel (HDD) engine test designed to evaluate the soot handling ability of a lubricant. This study aims to understand what properties of diesel soot produced under certain conditions contribute to loss of viscosity control through examination of the morphology, nanostructure and oxygen functionalization of particulates obtained from two heavy duty diesel engine tests with different levels of EGR. Particulate samples obtained from the used engine oil that lost viscosity control at relatively low soot levels showed that the soot in this case was more graphitic and had lower oxygen functionalization. 相似文献
18.
汽车发动机维修是一项既考验专业技能又突出实践经验的工作。汽车发动机故障原因比较多,对于不同类型的发动机故障需要采取相应的诊断技巧与维修方案。本文结合多年实践调查,以汽车发动机点火故障、发动机抖动故障、发动机烧机油故障以及冷却液故障为例,详细分析诊断技巧与维修经验,以此为今后实践教学提供经验。 相似文献