COLD ENGINE TRANSIENT FUEL CONTROL EXPERIMENTS IN A PORT FUEL INJECTED CFR ENGINE

摘要

Air-fuel mixture preparation is particularly challenging during cold engine throttle transients due to poor fuel vaporization and transport delays in port fuel injected (PFI) engines. In this study, a PFI Cooperative Fuels Research engine is used to evaluate torque and measure in cylinder and exhaust CO, CO_2 and unburned hydrocarbons during throttle transients at various early stages of engine warm-up. Fast flame ionization detectors and non-dispersive infra-red fast CO and CO_2 detectors are used to provide detailed cycle-by-cycle analysis. Torque after cold throttle transients is found to be comparable to steady state torque due to allowable spark advance. However, cold transients produce up to 4 times the unburned hydrocarbons when compared to steady state operation. Finally, the x-tau fuel control model is evaluated in this challenging operating regime and is found to provide poor transient fuel control due to excessive fueling.