Range extended electric vehicles (REEV) are gaining popularity due to their simplicity, reduced emissions and fuel consumption when compared to parallel or series/parallel hybrid vehicles. The range extender ICE can be optimised to a number of steady state points which offers significant improvement in overall exhaust emissions. One of the key challenges in such vehicles is to reduce the overall powertrain costs, and OEMs providing REEVs such as the BMW i3 have included the range extender as an optional extra due to increasing costs on the overall vehicle price. This paper discusses the development of a low cost auxiliary power unit (APU) for the range extender application utilising a well optimised production automotive two cylinder gasoline engine. The 624 cc production engine was further optimised given the project constraints of low cost changes to suit a range extender application. These changes included a new control system to allow for the introduction of an electronic throttle, modifications to the intake and exhaust manifolds and reduction in exhaust lambda enrichment to achieve the desired performance and fuel economy. Modifications to the intake/exhaust manifolds were initially modelled using GT-Power and validated by engine tests. This modifications improved the engine torque in the APU planned operating range, and the new control system achieved comparable BSFC at 3000 RPM catering for European grade fuel. The use of European grade fuel also allowed operation at lambda 1 across a wider portion of the engine operating range to further improve fuel economy. Further modification included replacing the mechanical coolant pump with an electric pump to reduce engine warmup duration and improve fuel economy.
|Publication status||Published - 5 Apr 2016|
|Event|| SAE 2016 World Congress & Exhibition - Detroit, USA United States|
Duration: 12 Apr 2016 → 14 Apr 2016
|Conference||SAE 2016 World Congress & Exhibition|
|Country||USA United States|
|Period||12/04/16 → 14/04/16|