Dynamic individual-cylinder analysis of a Gasoline Direct Injection engine emissions for cold crank-start at elevated cranking speed conditions of a Hybrid Electric Vehicle. (December 2022)

• Record Type: Journal Article
• Authors: Khameneian, Amir; Dice, Paul; Duncan, Joel; Naber, Jeffrey D.; Shahbakhti, Mahdi; Archer, Chad; Moilanen, Peter; Glugla, Chris; Huberts, Garlan
• Is Part Of: Control engineering practice. Volume 129(2022)
• Publication Date: 2022-12
• Subjects: SI engine -- GDI -- HEV -- Cold start -- Cranking speed -- Spark timing -- Valve timing -- Split injection -- Fuel factor -- Emissions -- HC -- CO/CO2 -- NOx; Automatic control -- Periodicals; 629.89
• DOI: 10.1016/j.conengprac.2022.105349
• Languages: English
• ISSNs: 0967-0661

Abstract

Abstract: The cold crank-start phase significantly contributes to the engine-out total emissions during the US Federal Test Procedure (FTP). A Gasoline Direct Injection (GDI) engine dynamics and emissions are investigated during the first three engine cycles of the cold crank-start in Hybrid Electric Vehicle (HEV) elevated cranking speed at 20 °C. To this end, the impact of the operating strategy on the individual-cylinder engine-out emissions is analyzed quantitatively. For this purpose, a new dynamic method was developed to translate the engine-out emissions concentration measured at the exhaust manifold outlet to mass per cycle per cylinder. The HEV elevated cranking speed provides valve timing control, throttling, and increased fuel injection pressure from the first firings. This study concentrates on analyzing the cranking speed, spark timing, valve timing, and fuel injection strategy and parameters effect on engine-out emissions. Design of Experiment (DOE) method is used to create a two-step multi-level fractional-factorial test plan with a minimum number of test points to evaluate the significant parameters affecting engine-out emissions during cold crank-start. Out of the first step DOE analysis, the optimal cranking speed, spark timing, and valve timing, which results in the lowest unburnt HydroCarbon (HC) and NOx emissions, are distinguished. Then, fixing the first step parameters at their optimal values, the second step is accomplished with the fuel injection parameters sweep. The split injection parameters, including the Start of the first Injection (SOI), End of the second injection (EOI), and split ratio (SR), in addition to the first cycle additive fuel factor, are investigated. Results show that the high cranking speed with stabilized low Manifold Absolute Pressure (MAP), highly-retarded spark timing, high valve overlap, late intake first injection, 30 CAD bTDC firing EOI, and low first cycle fuel factor reduces the HC emissions 94%. Highlights: A new method to quantify engine-out emissions in mass per cycle per cylinder. An engine-dyno test method to duplicate an HEV elevated cranking speed cold start. DOE methods to create a two-step multi-level fractional-factorial test plan. Analysis of different engine operating strategies' impact on engine-out emissions. Analysis of the valve timing impact on engine-out emissions from the first firing. Optimal control inputs trajectories resulting in the lowest HC and NOx emissions.