F2008-06-044
Reducing Fuel Consumption by a Global Vehicle System Approach: Engine and Vehicle Results
The EU set a new target of 130 g CO2/km for the NEDC test in 2012 and will support research efforts aimed at further reducing emissions from new cars to an average of 95g CO2 /km by 2020. To assist the OEMs to reach this ambiguous goal by maintaining end customer comfort and fun-to-drive, it is necessary for the supplier industry to understand and to optimize the functional interactions between the different vehicle and power-train components and the related control functions and between the different sub-systems. Finally, the reactions of the vehicle system to different user profiles have to be taken in account. This optimization and integration process needs increasingly the integration of different competences found within the OEMs, engineering companies and the different sub-system and component suppliers. To increase the added value of the products and services supplied, SiemensVDO teamed up with Lotus engineering in a project aiming at a better understanding and control of this integrated approach to develop improved engine design and system integration support. In a first step, SiemensVDO developed a simulation tool to asses the energy balance within the vehicle taking in account all physical processes and subsystems: the combustion engine, mechanical friction, the fuel system, thermal management including water and oil circuit and the electrical loads for different levels of hybridization. Some results will be presented. The detailed simulation methodology will be presented in a second paper. Based on this model, a production vehicle was chosen and equipped with a new prototype engine developed and supplied by Lotus within this cooperation project. The integrated design process for the engine hardware, the engine management system and the auxiliaries allowed the development and the realization of this prototype power-train in a very short time from white sheet to chassis dyno testing. The engine concept chosen is a 3-cylinder, 1.5 litre turbocharged engine with direct gasoline injection in central position, an integrated exhaust manifold, homogeneous combustion, double VVT and valve lift switching on the inlet valves. After engine dynometer calibration, the engine has been implemented in the base vehicle. The power-train features also an electrical water-pump and a crankshaft mounted electrical motor for a mild hybridization. The hybrid concept includes electrical energy storage by double layer capacitors. The vehicle is been calibrated for NEDC and driveability. The concept shows very competitive results in terms of fuel consumption. In addition to the power-train concept intended to achieve the CO2 emission target for the NEDC test, additional systems were integrated to improve the real life fuel economy in customer hands. This includes flow controlled in-tank fuel pump, a navigation system based driver assistance system to motivate for economical driving as well as tire pressure monitoring. The vehicle concept will be presented, together with engine results for part load and full load as well as detailed vehicle results for the NEDC. The presented downsized power-train concept will be discussed in comparison to competing power-train architectures as there are turbo Diesel, stratified GDI and gasoline full hybrid.
This abstract is supplemented by a PDF, which can be viewed here.
Session: Fuel Efficient Powertrains II