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MAHLE Powertrain has built a range-extended electric vehicle demonstrator, with a series hybrid configuration. The vehicle is intended to operate predominantly purely electrically. Once the battery state of charge is depleted a gasoline engine (range extender) is activated to provide the energy required to propel the vehicle. As part of the continuing development of this vehicle, MAHLE Powertrain has recorded data during real world driving, with the aim of further investigating the actual usage a range-extended electric vehicle under non-laboratory test conditions. The vehicle is instrumented with a data acquisition system which records physical parameters, for example coolant temperatures, as well as CAN-based data from the engine and vehicle management systems.

In a typical plug-in hybrid electric vehicle (PHEV) installation, there exist multiple, potentially separate, cooling circuits. These circuits may have individual cooling/heating requirements or they may have common aspects. Opportunities exist for combining circuits for series applications for cost, weight and efficiency benefits. However, careful consideration must be paid to the compatibility of these circuits both in terms of temperature range requirements, but also in terms of the thermal loading of the systems on the cooling circuits. This paper presents details of a cooling system for a PHEV demonstrator recently completed by MAHLE Powertrain. The opportunities for the integration of several cooling circuits, including the cabin heating, ventilation and air-conditioning (HVAC) system, to optimise the system from a cost, package-space and weight perspective are discussed.

This paper, which is the fourth of a series, presents the REEV demonstrator vehicle developed by MAHLE Powertrain, which features a specifically designed range extender unit. The previous papers describe the specification setting, detailed design and the development of the range extender engine. A current production gasoline fuelled compact-class car was used as a donor vehicle and converted into a range-extended electric vehicle (REEV). The all-electric driveline specification has been developed to meet the performance criteria set for the demonstrator, matching the acceleration and maximum speed capabilities of the conventional donor vehicle. Also, a target electric only range has enabled the battery pack capacity to be specified. The resulting vehicle is intended to reflect likely, near to market, steps to further the wider adoption of electric vehicles in the compact-class passenger car segment.

Emissions legislation, fleet CO₂ targets and customer demands are driving the requirements for reducing fuel consumption. This is being achieved in the gasoline market in the near term through the adoption of engine downsizing. In order to reduce fuel consumption further and in the wider real-world operating region complimentary technologies are being investigated and applied to an extreme downsized engine. In this paper future gasoline engine technologies are applied and experimentally assessed in terms of fuel consumption improvement whilst the impact of subsequent loadings on the thermal management system have been simulated, both over drive cycle and using real-world drive data.

The open MAHLE Flexible ECU (MFE) was developed and successfully implemented for controlling gasoline, diesel and hybrid engines. The increased demand of new functions development to address future powertrain challenges, such as lower fuel consumption, ever more stringent emissions legislative targets as well as the need to reduce development time and cost at the same time, led to the incorporation of the MFE functions in a co-simulation environment. The co-simulation environment consists of using the virtual engine developed with 1D or 3D numerical simulation tools and the functions of MFE developed with Simulink-Targetlink. This co-simulation approach allows modifying either the engine control or the engine itself. Regarding the engine control and its development, the existing and new functions were tested for the performance, emissions and behaviour changes on several production and prototype engines.

To improve the speed and accuracy of engine testing, the spark (gasoline)/injection (diesel) timing can be optimized based on the location of the 50% mass fraction burn point (α50) rather than the traditional approach of "sweeping" timing to find the most efficient point. Results from both gasoline and diesel engines show that setting α50 to around 8° ATDC gives optimum efficiency for most circumstances. An exception is the case of highly unstable combustion, where the misfire rate may also be strongly dependent on timing. For diesel engines this method is effective in finding the timing for best efficiency but in practice the chosen injection timing may be driven more by the need to optimize emissions. This technique has been implemented by incorporating a burn angle controller into the MAHLE Flexible ECU (MFE), a powerful and highly adaptable engine controller.

The need to meet ever more stringent emission legislations over the last decade has led to a significant increase in diesel engine complexity. A typical modern passenger car diesel engine now features variable geometry exhaust gas turbocharging and variable charge motion in combination with exhaust gas recirculation. Further improvements are still required and one technology that has the potential to improve fuel economy and reduce emissions is variable valve timing. This gives the ability to alter in-cylinder charge motion and effective compression ratio. In doing so, it not only alters in-cylinder pressures and temperatures, but also the operating point of the turbocharger and EGR system. This paper demonstrates how both 1-D and 3-D numerical simulation have been used in conjunction with engine testing to analyse the fundamental effects and separate the interactions.

This paper forms the third of a series and presents results obtained during the testing and development phase of a dedicated range-extender engine designed for use in a compact-class vehicle. The first paper in this series used real-world drive logs to identify usage patterns of such vehicles and a driveline model was used to determine the power output requirements of a range-extender engine for this application. The second paper presented the results of a design study. Key attributes for the engine were identified, these being minimum package volume, low weight, low cost, and good NVH. A description of the selection process for identifying the appropriate engine technology to satisfy these attributes was given and the resulting design highlights were described. The paper concluded with a presentation of the resulting specification and design highlights of the engine. This paper will present the resulting engine performance characteristics.

Current focus on techniques to reduce the tailpipe CO₂ emissions of road vehicles is increasing the interest in hybrid and electric vehicle technologies. Pure electric vehicles require bulky, heavy, and expensive battery packs to enable an acceptable drive-able range to be achieved. Extended-range electric vehicles (E-REV) partly overcome the limitations of current battery technology by having a "range extender" unit, which consists of an onboard fuel converter that converts a liquid fuel, such as gasoline, into electrical energy whilst the vehicle is driving. This enables the traction battery storage capacity to be reduced, whilst still maintaining an acceptable vehicle driving range. In a previous paper the power requirement of a range extender for a typical C segment passenger car was investigated using drive-cycle modeling over real-world cycles. This paper presents the detailed design of the range extender engine.

A new approach within the well-known trade-off in combustion process simulations between computational efforts (and thus the capability for engine operating map calculations) on the one hand, and accuracy of predictions on the other, has been developed and applied successfully to diesel combustion, in particular to energy release and pollutant formation. Using phenomenological models in combination with bio-inspired algorithms (for parameter identification), it is now possible to predict thermal, chemical and injection related engine characteristics over an entire operating map including different types of fuel (e.g. diesel, water-in-diesel emulsions and oxygenated diesel).