Engine Efficiency and Emissions Improvement in a Parallel-Series PHEV 2023-01-5072

While there is a continued push toward mass adoption of electric vehicles globally, internal combustion engines seem posed to continue to play a key role in the mobility industry even as electrified powertrains continue to increase in market share. For internal combustion engines to continue to propel people and goods, engine technologies need to continuously improve in both efficiency and emissions. This paper will explore six technologies to increase the efficiency and reduce the emissions output of an engine in a plug-in hybrid-electric vehicle (PHEV). The technologies employed on this prototype vehicle include deceleration fuel cutoff, start–stop, increasing the mean engine operating temperature, preheating the engine oil, implementing an electrically heated catalyst, and air–fuel ratio control. Each of these technologies have been well studied and have demonstrated robustness through decades of deployments on road. However, pairing these technologies with a PHEV architecture will enable the benefits of these technologies to be fully exploited. It will be demonstrated that the combined application of these six technologies increased the experimental vehicles miles per gallon gasoline equivalent by 22% and reduced greenhouse gas emissions by 32% over a real-world driving emissions baseline. This paper will explore the background and anticipated impacts that these technologies should have, as well as demonstrate their implementation on the experimental vehicle. Emphasis will be placed on the way each of these technologies were tested and the environment that they were tested in. The testing environments include an engine dynamometer, a chassis dynamometer, and real-world driving emission tests. In all these settings, the efficiency and emissions were measured. The final test involves a real-world driving emissions test. The vehicle in question is an experimental PHEV developed by students at The Ohio State University. Results and conclusions are drawn from the data collected for how each of these technologies impacted engine operation in the PHEV.