Analysis of Instability Factor for Fuel Economy Test on 4WD Chassis Dynamometer

By: Yasuhiro OGAWA

10 June 2014

The four-wheeled drive (4WD) chassis dynamometer has been continually improved by the evolution of power electronics technology and by the inherent design of the chassis dynamometer itself. The need for testing using the 4WD Chassis dynamometer is increasing due to the demand of fuel consumption and emission measurement of vehicles with complex powertrains such as HEVs (Hybrid Electric Vehicles) and PEVs (Pure Electric Vehicles). However, in many cases, the actual performance of 4WD chassis dynamometers has still not actually been confirmed. Accordingly, studies aimed at improvements of the repeatability of 4WD fuel consumption tests have been conducted and some key factors for improving stability and repeatability have been confirmed. It will be shown that most of the vehicle mechanical loss variability is due to the tires and therefore the stabilization of the mechanical losses of the test vehicle is essential for the test reproducibility.

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