重型天然气发动机电子节气门故障分析及性能优化

发布时间：2018-01-08 20:29

本文关键词：重型天然气发动机电子节气门故障分析及性能优化　出处：《江苏大学》2016年硕士论文　论文类型：学位论文

【摘要】：重型天然气发动机的研发和推广应用是降低尾气排放、减小环境污染的有效措施。重型天然气发动机是在保持柴油机大部分零部件通用的基础上,重点对进排气系统、配气机构等进行了重新设计,天然气发动机专用件均与电子控制单元相关联,与汽油发动机专用件具有一定互换性。本文以天然气发动机期初匹配的BOSCH电子节气门为研究对象,通过综合检测设备、FTA(故障树)、DOE全因子试验等软硬件技术深入分析产品结构缺陷并进行优化提升。本文首先根据天然气发动机电子控制单元控制策略和电子节气门工作原理,结合电子节气门台架试验特点和整车环境工作参数。选择合适电源及起源装置,确定了气门开度等控制参数,开发综合检测设备,并申报发明专利。该设备在故障件检测分析中广泛应用。其次,通过对故障产品的拆解分析,明确电子节气门故障模式。对故障模式和缺陷情况的分析表明,电子节气门滚针轴承(无轴端密封)结构是产品出现卡滞故障的重要原因,运用DOE试验模型进行轴承及轴端结构全因子试验,并通过电子节气门静态、瞬态台架试验进行充分验证,确定滚珠轴承+骨架油封结构优化方案,完成该方案下的电子节气门电机进行匹配性试验。最后,通过对盖板密封不严造成的功能失效件进行拆解分析,展开电子节气门盖板密封圈进行压缩率的计算,根据矩形密封圈静止密封特性,确定最优压缩率25%,最终确定矩形密封圈的厚度尺寸由3mm改为4mm,压缩率由14%提高到25%,并完成新结构产品的浸水和打压试验。以上试验结果均符合产品性能参数,产品释放前根据相关标准制定试验方案,设计完成高/低温存储、高温冲击、湿热循环、盐雾、振动测试、耐久性、耐化学试剂等8项型式试验,新结构电子节气门的型式性能均符合产品标准要求。新结构产品在完成台架试验和型式试验后,根据地域环境特点进行了整车道路试验验证,道路试验显示新结构的产品使用寿命较老结构产品有明显增长,在原来5万公里的基础上延长近1倍,故障率由期初的2.78%下降到0.79%,新结构产品已在WT系列重型天然气发动机上完成切换上场,并逐步在MT系列重型天然气发动机上推广使用。
[Abstract]:The development and application of heavy-duty natural gas engine is an effective measure to reduce exhaust gas emission and reduce environmental pollution. Heavy natural gas engine is based on maintaining the common use of most parts of diesel engine. The re-design of intake and exhaust system and valve distribution mechanism is emphasized, and the special parts of natural gas engine are all related to electronic control unit. This paper takes the BOSCH electronic throttle which matches the natural gas engine at the beginning of the period as the research object, through the comprehensive inspection equipment FTA (fault tree). The software and hardware techniques such as DOE full-factor test are used to analyze the defects of the product structure and optimize the structure. Firstly, according to the control strategy of the electronic control unit of natural gas engine and the working principle of electronic throttle. Combined with the characteristics of the electronic throttle bench test and the working parameters of the whole vehicle environment, the suitable power supply and the origin device were selected, the control parameters such as valve opening were determined, and the comprehensive testing equipment was developed. The device is widely used in fault detection and analysis. Secondly, through disassembly and analysis of fault products, the fault mode of electronic throttle is clear. The analysis of fault mode and defect shows that. The structure of electronic throttle needle roller bearing (without shaft end seal) is an important reason for the stagnation of the product. The DOE test model is used to carry out the full factor test of the bearing and shaft end structure, and the static state of the electronic throttle is adopted. The transient bench test was carried out to confirm the optimization scheme of the ball bearing skeleton oil seal and the matching test of the electronic throttle motor under the scheme was completed. Finally. Through disassembling and analyzing the functional failure parts caused by the loose sealing of the cover plate, the compression ratio of the electronic throttle cover plate seal ring is calculated. According to the static sealing characteristics of the rectangular seal ring, the optimal compression ratio is determined to be 25%. Finally, the thickness of the rectangular seal ring is changed from 3 mm to 4 mm, and the compression ratio is increased from 14% to 25%. The above test results all accord with the product performance parameters. Before the release of the product, according to the relevant standards to formulate the test plan, design the high / low temperature storage, high temperature impact. Moisture and heat cycle, salt spray, vibration test, durability, chemical resistance, etc. 8 types of tests. The new structure electronic throttle's type performance all conforms to the product standard request. After the new structure product completes the bench test and the type test, carries on the entire vehicle road test verification according to the regional environment characteristic. The road test shows that the service life of the new structure product is obviously longer than that of the old one, and the service life of the new structure product has been increased by nearly twice as much as the original 50,000 km, and the failure rate has decreased from 2.78% at the beginning of the period to 0.79%. The new structure product has been used in WT series heavy natural gas engine, and has been popularized in MT series heavy natural gas engine step by step.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK433

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