Dynamic Cylinder Deactivation of ICE - Simulation Methodology 2021-01-0682
Cylinder deactivation is a well-known approach to reduce the displacement of the ICE during its operation. This helps increase specific load of active cylinders and thus improve ICE efficiency. In serial production, cylinder deactivation is massively utilized in the static form, which keeps a set of cylinders deactivated for the time of the low load operation mode. An advanced cylinder deactivation can be applied in a dynamic form, in which all or a set of cylinders follow a specific deactivation pattern, which consist of a number of firing and deactivated cycles. This consequently forms a new basic repeating unit of the engine, so called supercycle. Such a deactivation strategy allows to dynamically vary the engine displacement in finer steps even for a small number of cylinders. It enables higher displacement reduction, while keeping better NVH, uniform thermal and mechanical stresses in the engine, compared to the conventional deactivation. There have been a few papers that dealt with such deactivation strategy, but none of them has focused in detail on the whole thermodynamics, e.g., gas exchange process and inherent cylinder content during deactivated cycles, gas dynamics in the manifolds and associated variation of volumetric efficiency of firing cycles related to applied cycling patterns. Our work analyzes this phenomenon and proposes the methodology for reliable simulation of the dynamic cylinder deactivation by a 1-D code. This unveils all benefits and also the obstacles that must be coped with not even in the simulation domain, but also in the real engine control. The developed methodology is applied on a model of a spark ignition engine and first results are discussed.