Considerations for achieving equivalence between hub- and roller-type dynamometers for vehicle exhaust emissions

Emissions from vehicles can be measured on the road or in laboratories using dynamometers that simulate the forces that a vehicle is subject to while driving on the road. In the light-duty vehicle regulations, only roller-type dynamometers are allowed. For hub-type dynamometers, due to the direct connection of the dynamometers to the wheel hubs, additional parameters that are used are rotational mass, dynamic wheel radius, and tire force-slip relationship. Following up on an experimental study which showed that equivalent emission results can be achieved between roller- and hub-type dynamometers this work presents and evaluates methods to determine parameters used by hub-type dynamometer for mimicking roller-type dynamometer behavior. It also discusses methods to determine the parameters to simulate specific road conditions or when using only a hub-type dynamometer. The results show that using a constant dynamic radius for each wheel and a linear tire force-slip relationship is sufficient for emission measurement because typical errors in these parameters are practically negligible. A typical error in rotational mass results in a minor error in the determined forces during coastdown, but the typical accuracy of this parameter is in parity with the difference allowed in the regulation.

ENGSTRÖM Christian;  ÖBERG Per;  FONTARAS Georgios;  GIECHASKIEL Barouch; 

2022-10-19

MDPI

JRC130761

1996-1073 (online),   

https://www.mdpi.com/1996-1073/15/20/7541,    https://publications.jrc.ec.europa.eu/repository/handle/JRC130761,   

10.3390/en15207541 (online),