The Experiment Research Of SCR System In Euro Ⅳ Diesel Engine

As to the exhaust gas from the diesel engine, Nitrogen Oxide is the key controlled factor. With the development of the emission regulations are more and more strict, it’s not enough to reach the requirement of the regulation only by the ways of diesel internal clearing. So we need to find a more effective and economic method to replace the old ways. SCR can be accepted by more and more diesel manufacturer; the principle of the SCR system is that the engine can reduce the particular material to the limit range by the internal clearing ways at first. Then according to the selectable catalyst reduction to decrease the emission of NOx, so the SCR technical can meet the requirement of the Euro IV and Euro V emission regulation. And it’s still not sensitive to the sulfur in the diesel fuel and suitable for the heavy duty diesel engine. And till now, this technology has been accepted by most of the diesel engine manufacturer, SCR should be one of the most effective methods to reduce the NOx.Firstly, the paper mainly tells us the three kinds of the emission regulation in the world to introduce the emission regulation which has been implemented in china, so it tells us the requirement of emission limit. Then introduce the total control strategy of the SCR system, it includes the composing of SCR, working principle of SCR, design of control method in SCR, and the thermal management of the SCR system. According to the total control strategy of the SCR system, I introduce the metering dosing control strategy of the urea pump importantly. It include five modules:the urea dosing steady control module, EGP bed temperature modifying module, EGP ammonia storage modifying module and the dosing control module in urea pump. It’s only for the requirement of the accuracy of urea dosing.As to the research of the SCR control system, then I do the emission test in the engine test cell, I mainly do the ESC and ETC test according to the requirement of the GB17691emission regulation, compare the engine out result and system out result to validate the ability of the SCR system to reduce the NOxin exhaust gas, the result of the decrease effective in NOxreach90%, so it can make the emission result reach the requirement of regulation limit range.At last, I introduce the OBD control system in the paper, just like the application in the Euro IV diesel engine of the SCR system; it mainly includes the requirement of the engine from the OBD, the monitor strategy research and diagnoses methods with OBD, and the emission monitor with the NOX in the exhaust gas.So from this paper, you can see that the progeny of the research about the development of the Euro Ⅳ diesel engine with the SCR system have some reference value to the society, and also have the important and far-reaching significance for the NOX decrease in diesel engine and reduce the environment pollution.