Universal SCR Reductant Injection System Design And Evaluation

In recent years, faced with the energy shortage, environmental hazards and highoil prices, China will transform the system, which is the low carbon, environmentalprotection, efficient use of energy one rapidly, eager to develop no pollution andcheap energy instead of the traditional energy. In this transition period, the car forenergy saving and emission reduction will become one of the significant content ofchange road, thereinto, as the one of the engine post-processing technology that isSCR(SCR，Selective Catalytic Reduction) is undoubtedly a good transition route.Provided by the high fuel efficiency and NOx ultra-low emission the function, SCR isnot only the future emission control development important trend, but also fit forChina national conditions of automobile emission control line.The core of SCR post-processing system is the reducing agent quantitativeinjection control unit, for this part of the research, we have already had a lot ofindependent research and development of products. Unfortunately, these productstructure, control strategy, signal model as always followed a pattern of foreigncountries, just one standard, lack of generality, can not support the industrywideimprovement. The main reason is that SCR just exploited with the electric controlsystem at the same time, but there are some shortages we are unable to research anddevelop all by ourselves, about the engine industry in the electronic control andpost-treatment system, the overall unit of intergration and embarkation. Besides,thereason why foreign technology monopoly is after-treatment system is expensive.Build general-purpose SCR reductive agent injection system mainly divided intothree sections:1. No gas auxiliary SCR reductant quantitative injection system development,including System architecture to determine and core subsystem development, controlunit development, reducing agent nozzle test. 2. High-accuracy, low cost NOx sensor development, core componentsdevelopment, sensor integration and sensor evaluation.3. Self-learn building the closed loop control algorithm. Build the total NOxdensity estimate model, the NOx transformation efficiency model and the ammonianitrogen proportion. Achieve to the learning of injection control, the systemserviceability evaluating and optimizing again.The paper mainly discusses the open loop control system frame and experimentalverification, the main work contents are as follows:1. Analysis approach to the system development status and the significance ofindependent development system at home or abroad.2. Master the design concept, structure and working process of universal SCRreductive agent quantitative injection control system, besides, the difference from thetraditional SCR injection system.3. Do the nozzle of this system quantitative analytical test, the minimum amountdetermination, injection quantity sprayed determination, injection quantity stability ofuncertain linear and injection through distance.4. SCR reductive agent quantitative injection system hardware lectotype ordesign, software each module function introduced and application, PC softwaredeveloped and system steady control planned.5. Do SCR reductive agent quantitative injection system of diesel engine premisepreparation, including peripheral equipment and system components of the connection,drawing up the test plan, test data and results analysis record, Finally NOx conversioncan be the feasibility of the verification system.