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点火提前角控制是天然气发动机控制的最重要内容之一,精确控制点火提前角涉及到发动机运行的动力性和经济性。对此,开发采用BP神经网络控制的方法来实现天然气发动机的点火提前角控制问题,并基于发动机平均值模型进行了神经网络的MATLAB在线仿真。结果表明:点火提前角最大绝对误差0.4°CA,最大相对误差1.5%,该优化控制模型能准确地获取天然气发动机最佳点火提前角。 相似文献
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采用GT-Power软件建立模型,模拟某VVT汽油机的工作过程,分析在汽油机上直接燃用M15燃料时动力性下降的原因,并以恢复原机动力性能为目标进行优化,把优化后的M15发动机与原机性能进行对比,指出优化原汽油机点火提前角可以提高M15发动机的动力性能。 相似文献
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(1)首先要调整好发动机的喷油(或点火)提前角,防止因为喷油(或点火)时刻过早造成曲轴反转,这是预防启动发动机时发生意外人身伤害的关键技术措施。 相似文献
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将1台点燃式二冲程气道喷射汽油机改造为缸内直喷煤油发动机,在3000r/min小负荷工况下进行了点火提前角、喷气结束角、过量空气系数对性能影响的试验研究。结果表明,喷气结束角为50°和80°(上止点前)时,适当增大点火提前角,能使功率增加、油耗降低,但点火提前角不宜过大,否则会造成HC和CO排放量的增加;点火提前角为15°和30°(上止点前)时,适度提前喷气结束时刻,可以使功率增加、油耗和排放降低;另外,偏浓混合气有利于提高功率输出,偏稀混合气有利于降低排放。 相似文献
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二冲程煤油发动机整机建模与初始点火提前角计算分析 总被引:2,自引:0,他引:2
针对二冲程汽油发动机改燃烧航空煤油后,初始点火提前角需重新标定的问题,利用GT-Power对以煤油为燃料的二冲程发动机进行整机建模。通过数值计算分析了转速、负荷、进气压力、进气温度和空燃比对点火提前角的影响,得出除转速和负荷外,进气温度对点火提前角的大小影响明显。针对不同的工况条件,充分考虑动力性而忽略经济性与排放性的前提下,通过计算获取了发动机初始点火提前角;通过仿真数据与实验结果对比验证了其一致性。 相似文献
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Duk-Sang Kim Young-Joon Park Seang-Wock Lee Yong-Seok Cho 《Journal of Mechanical Science and Technology》2008,22(1):141-147
Emission regulations for automobiles have become more stringent and the improvement of emission during cold start has been
a major key issue to meet these regulations. Among many kinds of factors that affect cold start operation, ignition timing
is crucial to improve emission characteristics due to the influence on exhaust gas temperature. Recent progress in variable
valve timing allows optimized valve event strategies under various ranges of engine operating conditions including cold start.
This study investigates effects of ignition and exhaust valve timing on exhaust gas temperature, combustion stability and
emission characteristics through cold start bench tests of an SI engine.
Experimental results show that exhaust valve timings and ignition timings significantly affect exhaust gas temperature and
stability of engine operation under cold start condition. Exhaust valve timing also affects CO and NOx emission due to changes in residual gas fraction of the combustion chamber. Ignition timing mainly affects exhaust gas temperature
and HC emission. A control strategy, advanced exhaust valve timing and retarded ignition, is plausible in order to achieve
reduction of exhaust emission while maintaining stability under cold start operation of SI engines. 相似文献
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通过对发动机辅助制动工作过程进行理论分析,建立了发动机辅助制动计算模型,根据辅助制动相关参数(包括排气门开度、发动机转速和排气背压等),对发动机辅助制动进行了单因素和多因素条件下的仿真研究及试验验证。结果表明:随着发动机转速的升高,缸内压力增大,且压力峰值更靠近上止点;制动扭矩随转速的升高而增大,减压制动时制动扭矩最大,发动机制动时制动扭矩最小;发动机转速一定时,泄漏制动和减压制动分别有一对应的最佳排气门开度值,并且转速越高,排气门开度最佳值越大,排气背压越高,制动扭矩越大。 相似文献
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M. Kannan R. Karthikeyan B. Deepanraj R. Baskaran 《Journal of Mechanical Science and Technology》2014,28(2):729-737
In the present investigation a volatile fraction of Pinus resin called Turpentine has been experimented in a direct injection diesel engine under HCCI combustion mode. The engine chosen to experiment is a single cylinder DI diesel engine and modified in such a way to ignite Turpentine in a diesel engine under HCCI mode. As the Turpentine has a higher self ignition temperature the ignition of Turpentine in regular diesel engines with auto-ignition is not possible. Hence, suitable modification is made in the engine to ignite Turpentine in a diesel engine like diesel fuel. The modified engine has ECM controlled fuel spray and an air preheater in the suction side of the engine. The combined effort of adiabatic compression and supply of preheated air ignites turpentine by auto-ignition and its timing of ignition is precisely controlled by changing intake air temperature. This investigation revealed that the engine operated with turpentine performed well with little loss of brake thermal efficiency. And, emitted comparatively lower emissions such as NOx and smoke and proved that the turpentine is a best suited fuel for HCCI operation. 相似文献
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首先采用多维数值模拟的方法解析了从天然气喷射阀喷出的突发天然气喷流的发展过程,并由纹影试验验证了这个数值解析方法的可行性。在此基础上,解析了单进气阀和双进气阀发动机进气歧管内天然气的喷射和反射过程。结果表明,大量天然气与进气阀冲突后向进气歧管入口方向反射并造成进气阀附近气体压力升高;若进气歧管较短时,天然气-空气混合气反射到歧管入口并造成各缸混合气分配不均匀是完全可能的;即使较长的进气歧管时,由于发火顺序不同,各缸间的进气干涉程度也不一样,这将引起各缸实际的进气充量发生变化。 相似文献
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A two-stroke Schnurle-type gasoline engine was modified to enable compression-ignition in both the port fuel injection and
the in-cylinder direct injection. Using the engine, examinations of compression-ignition operation and engine performance
tests were carried out. The amount of the residual gas and the in-cylinder mixture conditions were controlled by varying the
valve angle rate of the exhaust valve (VAR) and the injection timing for direct injection conditions. It was found that the
direct injection system is superior to the port injection system in terms of exhaust gas emissions and thermal efficiency,
and that almost the same operational region of compression-ignition at medium speeds and loads was attained. Some interesting
combustion characteristics, such as a shorter combustion period in higher engine speed conditions, and factors for the onset
of compression-ignition were also examined. 相似文献
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全可变气门机构闭环控制试验研究 总被引:1,自引:0,他引:1
为进行均质充量压缩燃烧的研究,开发一套进气门升程和相位、排气门升程和相位等4个参数均可独立自由控制的全可变气门机构。同时为研究可变气门技术的控制策略,开发一套全可变气门机构控制策略研究试验平台,包括一台变频调速电动机、液压及润滑系统、全可变气门机构控制单元及其试验管理系统,该平台可在模拟发动机运行的条件下进行气门机构控制策略研究和评价。对可变升程和可变相位闭环控制策略的试验研究结果表明,整套策略可以实现进排气门升程在0~9.7 mm之间、相位在60°范围内连续、快速、稳定的调节,为提高汽油机的效率和实现均质充量压缩燃烧发动机的运行控制奠定了基础。 相似文献
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A computer program has been developed to predict the engine performance characteristics through the analysis of the flow in the intake and exhaust systems and of the cylinder combustion phenomena for the MPI spark ignition engines. Using the program, a study for the optimal design of the intake system has been performed by varying the factors which can influence the volumetric efficiency, such as the volume of the plenum chamber, the length of the intake manifold and the pipe length between the surge tank and the plenum chamber. Experimental tests have also been carried out to obtain the transient pressure history in the intake manifold and the cylinder, and the variations of volumetric efficiency over the various engine speeds. The result of simulation has been compared with that of experimental test, and the optimal design data for the test engine could be found. The comparison of volumetric efficiency shows good agreement between the simulation and experiment. 相似文献
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Jae Keun Park Sang Man Lee Young Sik Jeong Jae Ou Chae 《Journal of Mechanical Science and Technology》1998,12(5):956-962
An experimental study was conducted on a single cylinder direct injection diesel engine to investigate the effects of diluting intake air, with different gases and increasing intake pressure on combustion process and exhaust emissions. The intake O2 concentration is changed from 15% to 21% by diluting intake air with different gases (CO2, Ar, N2), and the intake pressure is changed from one to two bar by a screw compressor. A modified program for calculating heat release rate, is used to study the characteristics of combustion and exhaust emissions in detail. The main results show that the addition of either CO2 or Ar to the intake air increases the ignition delay. The variations of ignition delay with CO2 are much larger than those of ignition delay with Ar for the same O2 concentration. The emission of NOx decreases with the decrease of O2 concentration and the smoke level is lower with the addition of the CO2 than with that of Ar. As the intake pressure is increased, the ignition delay is shortened. Furthermore the high intake air pressure enhances the air-fuel mixing and diffusion combustion, and reduces the premixed combustion, so that NOx emission is decreased without increasing smoke emissions. The addition of CO2 at high intake pressure, drastically reduces NOx emissions and smoke emission simultaneously at a high load condition, and the addition of CO2 reduces NOx emissions without affecting the smoke emissions substantially at a low load condition. A zero-dimensional combustion simulation program incorporated with the present heat release correlation and ignition delay correlation is used to predict ignition delay, cylinder pressure and engine power. The results show that the correlations are likely to be adequate for the engine operating under diluted intake air and various intake pressure. 相似文献