In this paper, early exhaust valve opening (EVO) is applied to a diesel engine for fast warm up of the selective catalytic reduction (SCR) system with the ultimate goal of tailpipe NO_x emissions reduction. By advancing EVO from top dead center, the exhaust gas temperature increases and the exhaust flow reduces, influencing the enthalpy available to warm up the SCR, and the engine-out NO_x emissions increase or decrease depending on the engine’s operating conditions. Therefore, proper management of EVO is required to ensure that (1) engine-out NO_x emissions do not increase when the SCR catalyst is cold; (2) heat transfer to the SCR increases and it warms up faster than the baseline operation (without EVO phasing); and (3) fuel consumption increase is minimal. A novel model predictive controller (MPC) is proposed for this application, assuming a limited preview of the drive cycle is available. For the MPC, an optimization objective function is applied such that a sequential warm up strategy can be implemented for the aftertreatment system catalysts. Using this technique, the prediction horizon for effective thermal management of the slow SCR system is reduced. In addition, a rule-based logic is offered as an alternative to the predictive controller to calculate the EVO trajectory with less computational power. Observations based on optimization problems solved by dynamic programing (DP) were used to develop the rule-based controller. Both the rule-based logic and model-based MPC are tested with a detailed high fidelity one-dimensional model in a model-in-the-loop simulator. Results indicate the potential of an EVO phasing system with the proposed controllers to reduce tailpipe NO_x by 10% and 25% for the world harmonized transient cycle (WHTC) and federal test procedure (FTP), respectively. The rule-based controller has been found to be sensitive to the test drive cycle while the model based MPC shows a consistent performance, that is, independent of the test trajectory.

在本文中，排气门提前开启（EVO）被施加到的柴油发动机用于快速与尾管的最终目标温NO的选择性催化还原（SCR）系统的高达_X排放量减少。通过从上死点前进EVO，排气温度上升，排气流量减少，影响的焓可用于预热SCR，和发动机排出的NO _X的排放量增加，或者根据发动机的操作条件下降。因此，需要EVO的适当管理，以确保（1）发动机排出的NO _XSCR催化剂冷时，排放不会增加；（2）到SCR的热量传递增加了，并且预热的速度比基线操作快（无EVO调相）；（3）油耗增加最小。假设可提供有限的驾驶周期预览，则针对该应用提出了一种新型的模型预测控制器（MPC）。对于MPC，应用优化目标函数，以便可以为后处理系统催化剂实施顺序预热策略。使用此技术，可以降低慢速SCR系统有效热管理的预测范围。另外，基于规则的逻辑可作为预测控制器的替代方案，以较少的计算能力来计算EVO轨迹。基于通过动态编程（DP）解决的优化问题的观察结果被用于开发基于规则的控制器。在循环模型模拟器中，使用详细的高保真一维模型对基于规则的逻辑和基于模型的MPC进行了测试。结果表明，采用所提出的控制器的EVO调相系统具有减少尾管NO的潜力。_X 10％和世界25％的统一瞬时周期（WHTC）和联邦试验程序（FTP），分别。已发现基于规则的控制器对测试驾驶周期敏感，而基于模型的MPC显示出一致的性能，即与测试轨迹无关。