Combustion and HC&PN Emission Characteristics at First Cycle Starting of Gasoline Engine under Lean Burn Based on Active Pre-Chamber 2024-01-2108

As a novel ignition technology, pre-chamber ignition can enhance ignition energy, promote flame propagation, and augment turbulence. However, this technology undoubtedly faces challenges, particularly in the context of emission regulations. Of this study, the transient characteristics of combustion and emissions in a hybrid electric vehicle (HEV) gasoline engine with active pre-chamber ignition (PCI) under the first combustion cycle of quick start are focused. The results demonstrate that the PCI engine is available on the first cycle for lean combustion, such as lambda 1.6 to 2.0, and exhibit particle number (PN) below 7×10⁷ N/mL at the first cycle. These particles are predominantly composed of nucleation mode (NM, <50 nm) particles, with minimal accumulation mode (AM, >50 nm) particles. It was observed that under a quick start engine speed of 800r/min, reducing the injection pulse width of pre-chamber and port fuel injection (PFI), advancing the injection timing of pre-chamber, delaying the injection timing of PFI, and delaying the ignition timing, all above lead to a decrease in PN. The lowest PN in the test was 4.6×10⁷ N/mL and the lowest HC concentrations were 308×10^-6. A strong correlation exists between AM concentration and indicated mean effective pressure (IMEP) as well as cumulative heat release. Conversely, hydrocarbon (HC) concentrations exhibit an opposing trend to AM concentration.