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Current focus on techniques to reduce the tailpipe carbon dioxide (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 drivable range to be achieved. Extended-range electric vehicles (E-REVs) partly overcome the limitations of current battery technology by having an onboard fuel converter that converts a liquid fuel, such as gasoline, into electrical energy whilst the vehicle is driving. Thus enabling the traction battery storage capacity to be reduced, whilst still maintaining an acceptable vehicle range. This paper presents results from a drive style analysis toolset that enable US and EU fleet vehicle drive data to be categorized and compared. Key metrics, such as idle frequency, idle duration, vehicle speed, and vehicle acceleration are analyzed.

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.

Gasoline engine downsizing is already established as a technology for reducing vehicle CO2 emissions. Further benefits are possible through more aggressive downsizing, however, the tradeoff between the CO2 reduction achieved and vehicle drivability limits the level of engine downsizing currently adopted by vehicle manufacturers. This paper will present the latest results achieved from a very heavily downsized engine, and resulting demonstrator vehicle, featuring eSupercharging in combination with a conventional turbocharger. The original 1.2 litre, 3-cylinder, MAHLE downsizing engine has been re-configured to enable a specific power output in excess of 160 kW/litre. Of key importance is a cost effective, efficient and flexible boosting system.

Gasoline engine downsizing is already established as a proven technology to reduce automotive fleet CO2 emissions by as much as 25 %. Further benefits are possible through more aggressive downsizing, however, the trade-off between the CO2 reduction achieved and vehicle drive-ability limits the level of engine downsizing currently adopted. This paper presents results showing the benefits of adding an eSupercharger to a very heavily downsized engine. Measurements are presented from a 1.2 litre, 3-cylinder, engine fitted with an eSupercharger in addition to a conventional turbocharger. The original MAHLE downsizing engine has been re-configured to enable a specific power output that exceeds 160 kW/litre. Of key importance is a cost effective, efficient and flexible boosting system.

In order to achieve the required future CO2 reduction targets, significant further development of both gasoline and diesel engines is required. One of the main methods to achieve this with the gasoline engine in the short to medium term is through the application of engine downsizing, which has resulted in numerous downsized engines already being brought to production. It is, however, considered that there is still significant further CO2 reduction potential through continued development of this technology. This paper considers the future development of gasoline engine downsizing in the short to medium term and the various technologies that can be applied to further increase the efficiency of operation. As such this paper covers, among other areas, fundamental engine layout and design, alternative boosting systems, methods of increasing part load efficiency and vehicle modelling, and uses analysis tools and engine test results to show the benefits achievable.

Electrohydraulic and electromechanical valve train technologies for four-stroke engines are emerging which allow much greater flexibility and control of the valve events than can be achieved using mechanically-based systems. Much of the work done on exploiting the benefits of these systems has been directed towards improving engine fuel economy and reducing emissions. In the present work a study has been made, using an engine simulation program, in to some of the possible benefits to engine performance that may be facilitated by the flexibility of fully variable valve train (FVVT) systems. The simulation study indicates that FVVT systems, limited by realistic opening and closing rates, provide sufficient range in the valve event duration and timing to enable the engine to produce very high specific outputs whilst achieving a high level of torque in the low- and mid-speed range.

One of the most expedient routes to improving in-vehicle fuel economy is to reduce the swept volume of an engine and run it at a higher BMEP for any given output. This can be achieved through pressure charging. However, for maximum fuel economy, particularly at part-load, the compression ratio (CR) should be kept as high as possible. This is at odds with the requirement in pressure charged engines to reduce the CR at higher loads due to the knock limit. Lotus has studied a pressure charging system which will allow a high compression ratio to be maintained at all times. This is achieved by deliberately over compressing the charge air, intercooling it at the resulting elevated pressure, and then expanding it, via a turbine, to the desired plenum boost pressure, ensuring a plenum temperature which can potentially become sub-ambient at full-load.

Turbulent Jet Ignition is an advanced spark initiated pre-chamber combustion system for otherwise standard spark ignition engines found in current passenger vehicles. This next generation pre-chamber design simply replaces the spark plug in a conventional spark ignition engine. Turbulent Jet Ignition enables very fast burn rates due to the ignition system producing multiple, widely distributed ignition sites, which consume the main charge rapidly. This high energy ignition results from the partially combusted (reacting) pre-chamber products initiating combustion in the main chamber. The distributed ignition sites enable relatively small flame travel distances enabling short combustion durations and high burn rates. Multiple benefits include extending the knock limit and initiating combustion in very dilute mixtures (excess air and or EGR), with dilution levels being comparable to other low temperature combustion technologies (HCCI), without the complex control drawbacks.

Extreme engine downsizing is a modern solution aimed towards the goal of meeting new emissions regulations for internal combustion engines. A higher percentage downsized engine will produce less CO2. By extension, a higher boost level is required to generate high engine torque performance. The transient load step of a higher boost system at low RPM is currently an issue for conventional boosting. Aeristech has developed an electric supercharger to be matched with a conventional turbocharger to create a new type of two stage boosting system and a simpler downsized gasoline engine usable in mainstream vehicle segments. Whereas most electric pressure charging devices are capable of transient output to alleviate turbo lag. The electric supercharger is capable of steady-state air delivery. This makes the electric supercharger a dual-function device, alleviating turbo lag and also supplementing the compressor map of the turbocharger or main boost device.

Present automobile development is keenly focused on measures to reduce the CO2 output of vehicles. Plug-in hybrid electric vehicles (PHEVs) enable grid electricity, which is clean in tail-pipe emissions terms, to be utilised whilst the on-board electrical storage has sufficient charge. MAHLE Powertrain and Protean have jointly developed a plug-in hybrid demonstrator vehicle based on a C-segment passenger car. The vehicle features Protean’s compact direct drive in-wheel motors with integrated inverters on the rear axle and retains the standard gasoline engine, and manual transmission, on the front axle. To support this one-off prototype, a flexible vehicle control unit has been developed, which is easily re-configurable and adaptable to any hybrid vehicle architecture.

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.

MAHLE has developed a heavily downsized demonstrator engine to explore the limits, and potential benefits, of engine downsizing. The 1.2 litre, 3-cylinder, MAHLE downsizing (Di3) engine, in conjunction with an Aeristech 48 V electric supercharger (eSupercharger, eSC), achieves a BMEP level of 35 bar and a specific power output in excess of 160 kW/litre. The eSupercharger enables high specific power output, good low speed torque and excellent transient response. The resulting heavily downsized engine has been installed into a demonstrator vehicle that also features 48 V mild hybridization. At specific power output levels above 90 kW/litre the engine is operated with excess fuel in order to protect the turbine from excessive exhaust gas temperatures. In this analytical study, the boosting system requirements to maintain lambda 1 fuelling, via the use of EGR, across the entire engine operating map for the eSupercharged version of the MAHLE Di3 engine, have been explored.

The main focus nowadays for the development of future vehicle powertrain systems is the improvement in fuel efficiency alongside the reduction of pollutant emissions and greenhouse gasses, most notably carbon dioxide. The automotive community is already engaged in seeking solutions to these issues, however, the ideal solution, namely zero emission vehicle is still regarded as being a long way from fruition for the mass market. In the meantime steps are being taken, in terms of engineering development, towards improved fuel efficiency and sustainability of relatively conventionally powered vehicles. One approach to the decarbonization of road vehicles is to supplement existing fossil fuels with sustainable biofuels.

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.

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.

The automobile industry is under intense pressure to reduce carbon dioxide (CO2) emissions of vehicles. There is also increasing pressure to reduce the other tail-pipe emissions from vehicles to combat air pollution. Electric powertrains offer great potential for eliminating tailpipe CO2 and all other tailpipe emissions. However, current battery technology and recharging infrastructure still present limitations for some applications, where a continuous high-power demand is required. Furthermore, not all markets have the infrastructure to support a sizeable electric fleet and until the grid energy generation mix is of a sufficiently low carbon intensity, then significant vehicle life-cycle CO2 savings could not be realized by the Battery Electric Vehicles. This investigation examines the effects of combustion, efficiencies, and emissions of two alcohol fuels that could help to significantly reduce CO2 in both tailpipe and the whole life cycle.

Vehicle manufacturers are facing increasing legislative pressure to reduce vehicle emissions and achieve zero tailpipe CO2 emissions within the coming decade. The focus on techniques to reduce the tailpipe CO2 emissions, rather than vehicle lifecycle emissions, naturally dictates electrified solutions. However, this will not address the increased emissions resulting from vehicle manufacture, the emissions of the legacy fleet, or enable niche or classic applications, to be decarbonised for future use. The use of bio-derived fuels, and fully synthetic fuels, can provide a technical solution to these challenges, but it is beneficial if these can be used as a drop-in replacement to existing fossil derived fuels, as this would enable straight-forward backward compatibility with existing vehicles and avoid the need to re-engineer future engine designs or upgrade existing hardware.

Computer programs that simulate the wave propagation phenomena involved in manifold tuning mechanisms are used extensively in the design and development of internal combustion engines. Most comprehensive engine simulation programs are based on the governing equations of one-dimensional gas flow as these provide a reasonable compromise between modelling accuracy and computational speed. The propagation of pressure waves through pipe junctions is, however, an intrinsically multi-dimensional phenomenon. The modelling of such junctions within a one-dimensional simulation represents a major challenge, since the geometry of the junction cannot be fully represented but can have a major influence on the flow. This paper introduces a new pressure-loss junction model which can mimic the directionality imposed by the angular relationship of the pipes forming a multi-pipe junction. A simple technique for estimating the pressure-loss data required by the model is also presented.

An expedient route to improving in-vehicle fuel economy in 4-stroke cycle engines is to reduce the swept volume of an engine and run it at a higher BMEP for any given output. The full-load performance of a larger capacity engine can be achieved through pressure charging. However, for maximum fuel economy, particularly at part-load, the expansion ratio, and consequently the compression ratio (CR) should be kept as high as possible. This is at odds with the requirement in pressure-charged gasoline engines to reduce the CR at higher loads due to the knock limit. In earlier work, the authors studied a pressure-charging system aimed at allowing a high CR to be maintained at all times. The operation of this type of system involves deliberately over-compressing the charge air, cooling it at the elevated pressure and temperature, and then expanding it down to the desired plenum pressure, ensuring a plenum temperature which can potentially become sub-atmospheric at full-load.