汽车尾气排放与检测设计

本科毕业设计（论文）开题报告

题目电控汽油发动机尾气检测装置设计与分析指导教师

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一、选题的目的、意义和研究现状

二、研究方案及预期结果

三、研究进度

四、主要参考文献

五、指导教师意见

摘要

随着我国经济的持续发展和汽车保有量的不断提升，由此而带来的环境污染问题也越来越严重。为应对越来越严格的排放标准，尾气检测装置得到广泛的应用。首先，三元催化装置减少了各种化学污染物尤其是氮氧化合物的排放，为使这个装置达到更合适的工作状态，必须使空燃比尽可能的保持在14.7水平；其次，通过在排气管中安装氧传感器，将尾气的氧含量信号反馈给ECU,它会在采集到如发动机转速、进气管压力等数据的基础上，调整喷油的脉宽，改变喷油量，以达到最佳的空燃比。

419QE发动机是我国较早的发动机型，仍然采用较为传统的化油器式供油系统，本文以此款发动机的数据作为设计电控系统的依据。

本文分析了汽车尾气排放物的种类及其生成机理以及它所产生的影响，阐述了国内外日益严格的排放法规，进一步说明电控汽油喷射的必要性和电子控制在解决尾气排放问题中所起的作用。

本文选择了待改进的发动机类型并取得了一些参数，也选择了各种传感器的类型和参数，还着重设计了由传感器（转速、进气门压力、氧传感器）到中央处理器再到执行器（喷油器）的整个电控电路。

本文还通过一些参数值确定并优化map图，为ECU控制喷油器和火花塞的工作提供了可靠的基础。选择单片机的类型并设计软件，实现预定的功能。

关键词：汽油发动机，尾气检测，单片机，控制

ABSTRACT

With China's sustained economic development and car ownership is on the rise, thus environmental pollution problems is becoming more and more serious. In response to increasingly stringent emission standards, exhaust gas detection devices are widely used. First, the three-way catalytic device have done a lot to reduce a variety of chemical pollutants, especially nitrogen oxides emissions.And in order to make the device more work in a more suitable station, air-fuel ratio must remain at 14.7 level as possible; second, through the oxygen sensor installed in the exhaust pipe and the signal on oxygen content in the exhaust gas backed to the ECU, it would be collected, such as engine speed, intake manifold pressure based on the data, and then adjuste the fuel injection pulse width, change the fuel injection quantity to achieve the best possible air fuel ratio.

419QE engine is the engine of our earlier model, still using more traditional carburetor-type fuel injection system, this paper use the engine data as the basis for design of electrical control system.

This paper analyzes the types of vehicle exhaust emissions and the formation mechanism and its impact，and introduce the increasingly stringent emissions regulations at home and abroad，and further shows the need for electronic control fuel injection and electronic control to solve the problem in the role of reducing emissions .

This paper choose the type of engine to be improved and make a number of parameters, and also choose a variety of sensors and their parameters, and focuses on the design of the electronic control circuit from the sensors (speed, intake valve pressure, oxygen sensor) to the CPU and then to the actuator ( injector) .

The article also identifies and optimizes Map diagram through a number of parameters，it provide a reliable basis for the ECU to control the fuel injectors and Ⅱintended function.

Key Words:Gasoline engine, exhaust gas detection, microcontroller, control