【作者】 邓伟；

【导师】 赵华； 谢辉；

【作者基本信息】 天津大学 ， 动力机械及工程， 2008， 硕士

【摘要】 基于全可变气门运动机构的气门参数控制燃烧技术是改善传统SI汽油机燃油经济性,提高动力性和降低排放的最为有效的途径之一。但是这也对发动机进气量的测量和控制提出了更高的要求。本文针对基于全可变气门机构汽油机进气量测量和控制问题,通过仿真和试验相结合的方法,开展了热膜式流量计在脉动气流作用下波形信号的特征值分析,全工况范围内气门参数控制SI燃烧进气流量控制的研究以及气门参数调节进气量的响应特性分析研究。通过对比气门参数控制SI燃烧,气门参数控制HCCI燃烧与传统的节气门控制负荷汽油机SI燃烧三种模式下热膜流量计波形特征信号发现:与传统的节气门控制负荷SI燃烧相比,气门参数控制燃烧的进气波形存在较大的脉动,传统的波形处理方法不能满足要求。对于气门参数控制燃烧来说,每循环的进气流量波形存在一个窗口,在该窗口内只需要进行简单的平均算法,就可以与质量流量得到很好的线性关系。该窗口的位置取决于发动机结构参数和运行状态。采用GT-Power仿真软件,通过仿真与试验相结合的手段对可变气门控制下的SI燃烧进行了研究,初步探索了进气门升程和相位对进气量的影响规律和调节方法。通过多维拟和的方法,对经过试验验证的仿真数据进行了精确建模,得到可以用于前馈控制进气量的预测公式,该公式算出的进气量与试验数据有很好的一致性。通过对气门相位及升程动态调整进气量的响应时间进行试验研究发现:当发动机缓加速时,进气控制可以兼顾燃油经济性。而在发动机急加速时,进气控制主要满足动力性需求,并通过对比不同气门参数组合对进气量的调整响应,发现存在一个最快调节进气量的气门参数控制路径,基本满足常用驾驶的需要。更多还原

【Abstract】 Variable valve technology is one of the most applicable measures to improving fuel economy, power performance and emissions of conventional SI engines. But this technology also has poised a higher demand for measurement and control strategies of engine mass air flow. This paper investigated on the accurate measurement of the intake mass and the control strategy for a Gasoline Engine which equipped with fully variable valve systems and this engine has been taken out the throttle body.Both of the simulation and experiment method is introduced in this research, the eigenvalue of the waveform from the hot film flowmeter which is effected by the pulsant airflow has been analyzed. The response characteristic and how the airflow is effected by the parameters of the valves the response characteristic is also studied on the full operation range.The results show that, compared to the traditional SI combustion mode, the intake air waveform is much more fluctuant on the combustion mode, and the traditional collection method cannot satisfy the requirement. A measuring window is found in every cycle in the intake airflow waveform on the combustion mode which depends on the parameters of the valves. The average value of the intake airflow waveform in this window has liner relationship with the intake air mass flow. The position of the window is effected by the structure and the operation mode of the engine, so the calibration is needed.Both the simulation and the experiment method is used to study the SI combustion which is controlled by the variable valve. The multidimensional fitting is introduced to modeling the simulation data which is validated by the experiment data. After the fitting, we found a formula which can be used on the feedforward control.We found that when the engine speed is increased slowly, the fuel economy is also good when the airflow is controlled by the valves. When the engine speed is increased fleetly, the dynamics is the most important. We also found a fastest route to adjust the parameters of the valves by compare the adjust response of the intake airflow on different combination of the parameters of the valves, which can fulfill the requirement of the usual drive.更多还原