【作者】 衣丰艳；

【导师】 周丛钜；

【作者基本信息】 广西大学 ， 农业机械化工程， 2002， 硕士

【摘要】 本文首先对配气机构的组成、气门间隙、配气相位进行了简单的介绍。接着对配气机构—气门组、气门传动组各组件的技术状态变化进行了系统分析，从而确定了配气机构技术状态诊断参数—配气相位和气门间隙。并介绍了配气相位和气门间隙的检查调整方法。以N485Q柴油机样机进行实验。先测出柴油机在正常技术状态下的性能参数。然后依次装上不同偏位角的四个偏位键，以改变发动机的配气相位，分别测出配气相位提前或落后2°、4°、6°、8°时的发动机性能参数，并与正常技术状态下的性能参数相比较，得出配气相位提前或落后对发动机动力性的影响规律。并以配气相位为变化依据，绘出该N485Q柴油机的配气相位调整特性曲线。接着运用多因素正交回归旋转组合设计方法，设计了配气相位、进气门间隙、排气门间隙、转速、负荷五个调整参数的实验，研究配气相位、进气门间隙、排气门间隙、转速、负荷五个调整参数相互匹配的情况对柴油机功率、油耗率和碳烟排放影响的规律。运用统计软件SPSS建立了功率、油耗率、烟度各项性能指标随上述五个调整参数而变化的数学模型，定量描述了各调整参数对发动机动力性、经济性和碳烟排放的影响。最后，利用计算机寻优，对最大扭矩工况和标定工况下的六个回归方程进行优化，得出各自理论的性能指标的最优值及其调整参数相应数值。并以此调整参数为依据。重新调整发动机，通过实验，测出其实际各项性能指标，并与理论值相比较。运用理论和实验相结合的方法，讨论确定了该N485Q柴油机的最佳调整参数(配气相位、进气门间隙和排气门间隙)的具体数值。 研究结果表明：配气相位提前时进、排气门提前角增大对柴油机运行的影响是有利柴油机高速运行；进、排气门延迟角减小对柴油机运行的影响是有利柴油机在较低转速运行；配气相位落后时，进、排气门提 前角减小对柴油机运行的影响是有利于柴油机在中速运行；进、排气门 延遏角增大对柴油机在较低转速下运行有不利的影响。配气相位、进气 门间隙、排气门间隙、转速、负荷五个调整参数之间是相互影响的。内 燃机在使用过程中，由于配气机构某些零件的磨损和紧固件的松动，各 参数的最佳调整值应有所变化，不宜始终按出厂值调整。计算机寻忧结 果与试验结果预报的误差在2％以下，结果是令人满意的。更多还原

【Abstract】 This thesis firstly states simply the build-up of valve mechanism, valve clearance and valve timing. Then, it is analysed systematically that the technology state of each assemblage of valve mechanism, which includes valve group and valve transmission group. Therefore, the diagnosis parameters of technology state of valve mechanism, which are valve timing and valve clearance are determined. Furthermore, this thesis also states the checking and adjusting method of valve timing and valve clearance. Next, the experiment iscarried out on N485Q DI diesel engine as an example. First of all, the performance parameters are measured under normal technology state of diesel engine. Then, the four keys of displacement are assembled in diesel engine in order to change the valve timing. The performance parameters are measured ahead or behind valve timing of 20,4?6?80 of diesel engine .And contrasted with the performance parameters under normal technology state, these parameters can give us the influence laws of power, economic performance and smoke emission of diesel engine ahead or behind valve timing. And then following this using orthogonal regression rotation design method, the experiment of five adjusting parameters (valve timing, admission valve clearance, emission valve clearance, rotation speed, load rate)is designed. The influence laws of power, oil consumption rate and smoke emission are researched under the circumstances of these five adjusting parameters’ (valve timing, admission valve clearance, emission valve clearance, rotation speed, load rate) mutual matching. Thus mathematical models including power, oil consumption rate and smoke emission concerning five adjusting parameters have been established with statistical software SPSS, the effects on power, economic performance and smoke emission are descripted batchingly of the five adjusting parameters. Finally, with computer looking for the best parameters, the six regression equations at maximum torque and at maximum power are optimized. The best values of each performance index in theory and the corresponding values of adjusting parameters are concluded. Based on these parameters, the engine is adjusted again, and each practical performance index is measured by experiment, and contrasted with the theoretical values. Finally, the best adjusting parameters of valve timing, admission valve clearance and emission valve clearance have been determined by theoretical and experimental method.The research result shows that the increases of admission and emission ahead angles to the running of diesel engine when valve timing advances is beneficial to the high speed running of diesel engine ,the decreases of admission and emission behind angles to the running of diesel engine when valve timing advances is beneficial to the low speed running of diesel engine ;and when valve timing falls behind, the decreases of admission andemission ahead angles to the running of diesel engine is beneficial to the middle speed running of diesel engine, the increases of admission and emission behind angles to the running of diesel engine is no benefit to the low speed running of diesel engine. The effects of five adjusting parameters of valve timing, admission valve clearance, emission valve clearance, rotational speed ,load rate are interacted. In the course of using internal combustion engine, because of the wear of some parts and loose of fasteners of valve mechanism, the best adjustment of each parameter should change and shouldn’t be adjusted invariably according to factory-produced value. The experimental result is satisfactory as the errors of the outcomes found out by computer for the best value and the experiment outcomes are within 2 percent.更多还原