A Study on Emission Measurement Method by Using Automated Intermittent Sampling for Real Driving Emissions of Gasoline Passenger Vehicles, Including Hybrid Electric Vehicles and Plug-in Hybrid Electric Vehicles 2022-01-1022

Electric vehicles have become more widespread globally, with the aim of realizing a carbon-neutral society. In addition, the various policies for vehicle engines have become increasingly strict. It is desirable to evaluate fuel consumption and exhaust emissions using real vehicles on actual roads, with the goal of improving air quality. Hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs) have a high frequency of engine stops during driving. In a real driving emission (RDE) test, a portable emission measurement system (PEMS) is used, which continues to measure emissions even when the engine stops; this can decrease the emission concentration inside the tailpipe and result in an inaccurate emission measurement. Furthermore, RDE tests are affected by the installation performance of the PEMS; the emission intake is often installed by extending the exhaust outlet. Gasoline vehicles have specific emission characteristics that pose an issue when the tailpipe at the muffler outlet is extended and the measurement is made after merging.

This study thus examines the methods for constructing the high-precision PEMS necessary for RDE evaluations for the increasingly common HEVs and PHEVs. In particular, the emission rates and sampling locations are investigated, and a method for operating the emission analyzer intermittently to synchronize with the engine is examined and evaluated.