Rapid warm-up of a diesel engine aftertreatment system (ATS) is a challenge at low loads. Modulating exhaust manifold pressure (EMP) to increase engine pumping work, fuel consumption, and as a result, engine-outlet temperature, is a commonly used technique for ATS thermal management at low loads. This paper introduces exhaust valve profile modulation as a technique to increase engine-outlet temperature for ATS thermal management, without requiring modulation of exhaust manifold pressure. Experimental steady state results at 800 RPM/1.3 bar BMEP (curb idle) demonstrate that early exhaust valve opening with negative valve overlap (EEVO+NVO) can achieve engine-outlet temperature in excess of 255°C with 5.7% lower fuel consumption, 12% lower engine out NO_x and 20% lower engine-out soot than the conventional thermal management strategy. Late exhaust valve opening with internal EGR via reinduction (LEVO+Reinduction) resulted in engine-outlet temperature in excess of 280°C, while meeting emission constraints at no fuel consumption penalty. This work also demonstrates that LEVO in conjunction with modulation of exhaust manifold pressure results in engine-outlet temperature in excess of 340°C while satisfying desired emission constraints. Aggressive use of LEVO can result in engine-outlet temperatures of 460°C, capable of active regeneration of DPF at curb idle, without the significant increase in engine-out soot emissions seen in previously studied strategies.

在低负荷下，柴油机后处理系统（ATS）的快速预热是一个挑战。调节排气歧管压力（EMP）以增加发动机泵送工作量，燃料消耗，从而提高发动机出口温度，是低负载下ATS热管理的常用技术。本文介绍了排气门轮廓调节技术，该技术可提高ATS热管理的发动机出口温度，而无需调节排气歧管压力。在800 RPM / 1.3 bar BMEP（路缘怠速）下的实验稳态结果表明，提前排气门打开且负气门重叠（EEVO + NVO）可以使发动机出口温度超过255°C，并降低5.7％的燃油消耗，12 ％下发动机排出NO _X与传统的热管理策略相比，发动机排出的烟灰降低了20％。排气阀延迟打开，并通过还原（LEVO + Reinduction）进行内部EGR导致发动机出口温度超过280°C，同时满足了排放限制，而无油耗损失。这项工作还证明，LEVO与排气歧管压力的调节相结合，可以使发动机出口温度超过340°C，同时满足所需的排放限制。过度使用LEVO可以使发动机出口温度达到460°C，能够在路缘怠速时主动再生DPF，而不会像以前研究的策略那样显着增加发动机排出的烟尘排放量。