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Powertrain electrification is becoming increasingly common in the transportation sector to address the challenges of global warming and deteriorating air quality. This paper introduces a novel “Build Your Hybrid” approach to experience and test various hybrid powertrain concepts. This approach is applied to the light commercial vehicles (LCV) segment due to the attractive combination of a Diesel engine and a partly electrified powertrain. For this purpose, a demonstrator vehicle has been set up with a flexible P02 hybrid topology and a prototype Hybrid Control Unit (HCU). Based on user input, the HCU software modifies the control functions and simulation models to emulate different sub-topologies and levels of hybridization in the demonstrator vehicle. Three powertrain concepts are considered for LCVs: HV P2, 48V P2 and 48V P0 hybrid. Dedicated hybrid control strategies are developed to take full advantage of the synergies of the electrical system and reduce CO2 and NOx emissions.

Downsizing is an effective way to further improve the efficiency of SI engines. To make most of this concept, the compression ratio has to be adjusted during engine operation. Thus, the efficiency disadvantages during part load can be eliminated. A fuel consumption reduction of up to 30% can be realized compared to naturally aspirated engines of the same power. After the assessment of several known concepts it turned out that the eccentric crankshaft positioning represents an appropriate solution which meets the requirements of good adjustability, unaltered inertia forces, low power demand of the positioning device and reasonable design effort. The basic challenges posed by the eccentric crankshaft positioning have been tackled, namely the crankshaft bearing and the integration of the newly developed power take-offs which have almost no influence on the base design.

By variation of the compression ratio the fuel consumption of high boosted gasoline engines can be reduced, due to operating with higher compression ratios at low load compared to an engine with fixed compression ratio. The two-stage VCR-system enables a high share of fuel saving potential relative to full variable systems. Considering a low cost manufacturability and a beneficial integratability into common engine architectures the length-adjustable conrod using an eccentric piston pin in the small eye has proved as the best concept. The adjustment is performed by a combination of gas and mass forces. This article describes the design of such a two-stage VCR-system as well as the functional testing under motored and fired engine operating conditions.

The problem with traditional drive cycle fuel economy analysis is that kinematic (backward looking) models do not account for transient differences in charge air handling systems. Therefore, dynamic (forward looking) 1D performance simulation models were created to predict drive cycle fuel economy which encompass all the transient elements of fully detailed engine and vehicle models. The transient-capable technology of primary interest was mechanical supercharging which has the benefit of improved boost response and "time to torque." The benefits of a supercharger clutch have also been evaluated. The current US class 6-8 commercial vehicle market exclusively uses turbocharged diesel engines. Three vehicles and baseline powertrains were selected based on a high-level review of vehicle sales and the used truck marketplace. Fuel economy over drive cycles was the principal output of the simulation work. All powertrains are based on EPA 2010 emission regulations.

While significant progress has been made in recent years to develop hybrid and battery electric vehicles for passenger car and light-duty applications to meet future fuel economy targets, the application of hybrid powertrains to heavy-duty truck applications has been very limited. The relatively lower energy and power density of batteries in comparison to diesel fuel and the operating profiles of most heavy-duty trucks, combine to make the application of hybrid powertrain for these applications more challenging. The high torque and power requirements of heavy-duty trucks over a long operating range, the majority of which is at constant cruise point, along with a high payback period, complexity, cost, weight and range anxiety, make the hybrid and battery electric solution less attractive than a conventional powertrain.

Regulated emissions, CO2-values, comfort, good driveability, high reliability and costs, this is the main frame for all future powertrain developments. In this frame, the diesel powertrain, not only for passenger cars, but also for commercial vehicle applications, faces some challenges in order to fulfil the future European and current US emission legislations while keeping the fuel consumption benefit, good driveability and an acceptable cost frame. One of these challenges is the varying fuel qualities of diesel fuel in different countries including different cetane number, volatility, sulphur content and different molecular composition. In addition to that in the future, more and more alternative fuels with various fuel qualities and properties will be launched into the market for economical and environmental reasons. At present, the control algorithms of the injection system applied in most diesel engines is open loop control.

Controlled Auto Ignition (CAI) as a promising future combustion process is a concept to strongly reduce fuel consumption as well as NOx emissions. The acceptance and the potential of this combustion process depends on the possible CAI operation range in the engine map and the fuel consumption benefit, as well as the complexity of the variable valve train which is necessary to realize the CAI combustion process. The thermodynamic investigations presented in this paper were done on an engine equipped with an electromechanical valve train (EMVT), featuring Port Fuel Injection (PFI) and direct Injection. They show that the electromechanical valve train is an excellent platform for developing the CAI process. Controlled Auto Ignition has been realized with port fuel injection in a speed range between 1000 and 4500 rpm and in a load range between approximately 1 and 6 bar BMEP (about 5 bar BMEP for pressure gradients lower than 3 bar/°CA) depending on engine speed.

The electrification of vehicle propulsion has changed the landscape of vehicle NVH. Pure electric vehicles (EV) are almost always quieter than those powered by internal combustion engines. However, one of the key challenges with the development of range extended electric vehicles (ReEV) is the NVH behavior of the vehicle. Specifically, the transition from the EV mode to one where the range extender engine is operational can cause significant NVH issues. In addition, the operation of the range extender engine relative to various driving conditions can also pose significant NVH concerns. In this paper internal combustion engines are examined in terms of their acoustic behavior when used as range extenders. This is done by simulating the vibrations at the engine mounting positions as well as the intake and exhaust orifice noise. By using a transfer path synthesis, interior noise components of the range extenders are calculated from these excitations.

Downsized direct-injected boosted gasoline engines with high specific power and torque output are leading the way to reduce fuel consumption in passenger car vehicles while maintaining the same performance when compared to applications with larger naturally aspirated engines. These downsized engines reach brake mean effective pressure levels which are in excess of 20 bar. When targeting high output levels at low engine speeds, undesired combustion events called pre-ignition can occur. These pre-ignition events are typically accompanied by very high cylinder peak pressures which can lead to severe damage if the engine is not designed to withstand these high cylinder pressures. Although these pre-ignition events have been reported by numerous other authors, it seems that their occurrence is rather erratic which makes it difficult to investigate or reliably exclude them.

Increasing shortages of energy resources as well as emission legislation development is increasing the pressure to develop more efficient, environmentally friendly propulsion systems for vehicles. Alternatives such as fuel cell systems or hybrid propulsion are in discussion or have already been introduced. This paper gives a survey on the present technical status of internal combustion engines, hybrid concepts and current fuel cell vehicles. Different solutions will be presented, so that an evaluation of advantages and drawbacks can be given. The further potentials of each concept, as well as combinations of different systems are discussed, and an outlook into the future is given.

Faced with one of the greatest challenges of humanity – climate change – the European Union has set out a strategy to achieve climate neutrality by 2050 as part of the European Green Deal. To date, extensive research has been conducted on the CO2 life cycle analysis of mobile propulsion systems. However, achieving absolute net-zero CO2 emissions requires the adjustment of the relevant key performance indicators for the development of mobile propulsion systems. In this context, research is presented that examines the ecological and economic sustainability impacts of a hydrogen-fueled mild hybrid vehicle, a hydrogen-fueled 48V hybrid vehicle, a methanol-fueled 400V hybrid vehicle, a methanol-to-gasoline-fueled plug-in hybrid vehicle, a battery electric vehicle, and a fuel cell electric vehicle. For this purpose, a combined Life-Cycle Assessment (LCA) and Life-Cycle Cost Assessment was performed for the different propulsion concepts.

When considered along with Phase 2 Greenhouse Gas (GHG) requirements, the proposed Air Resource Board (ARB) nitrogen oxide (NOx) emission limit of 0.02 g/bhp-hr will be very challenging to achieve as the trade-off between fuel consumption and NOx emissions is not favorable. To meet any future ultra-low NOx emission regulation, the NOx conversion efficiency during the cold start of the emission test cycles needs to be improved. In such a scenario, apart from changes in aftertreatment layout and formulation, additional heating measures will be required. In this article, a physics-based model for an advanced aftertreatment system comprising of a diesel oxidation catalyst (DOC), an SCR-catalyzed diesel particulate filter (SDPF), a stand-alone selective catalytic reduction (SCR), and an ammonia slip catalyst (ASC) was calibrated against experimental data.

Demanding CO2 and fuel economy regulations are continuing to pressure the automotive industry into considering innovative powertrain and vehicle-level solutions. Powertrain engineers continue to minimize engine internal friction and transmission parasitic losses with the aim of reducing overall vehicle fuel consumption. Strip friction methods are used to determine and isolate components in engines and transmissions with the highest contribution to friction losses. However, there is relatively little focus on friction optimization of Front-End-Accessory-Drive (FEAD) components such as alternators and Air Conditioning (AC) compressors. This paper expands on the work performed by other researchers’ specifically targeting in-depth understanding of system design and operating strategy.

Demanding CO2 and fuel economy regulations are continuing to pressure the automotive industry into considering innovative powertrain and vehicle-level solutions. Powertrain engineers continue to minimize engine internal friction and transmission parasitic losses with the aim of reducing overall vehicle fuel consumption. In Part 1 of the study (2017-01-0893) described aspects of the test stand design that provides flexibility for adaptation to various test scenarios. The results from measurements for a number of front-end accessory drive (FEAD) components were shown in the context of scatterbands derived from multiple component tests. Key results from direct drive and belt-driven component tests were compared to illustrate the influence of the belt layout on mechanical efficiency of the FEAD system. The second part of the series will focus exclusively on the operation of the alternator. Two main elements of the study are discussed.

Tier 4 emissions legislation is emerging as a clear pre-cursor for widespread adoption of exhaust aftertreatment in off-highway applications. Large bore engine manufacturers are faced with the significant challenge of packaging a multitude of catalyst technologies in essentially the same design envelope as their pre-Tier 4 manifestations, while contending with the fuel consumption consequences of the increased back pressure, as well as the incremental cost and weight associated with the aftertreatment equipment. This paper discusses the use of robust metallic catalysts upstream of the exhaust gas turbine, as an effective means to reduce catalyst volume and hence the weight and cost of the entire aftertreatment package. The primarily steady-state operation of many large bore engine applications reduces the complication of overcoming pre-turbine catalyst thermal inertia under transient operation.

For turbocharged engines high specific power and torque output as well as a fast transient response are mandatory. This conflict of aims can be solved by different charging systems, for example 2-stage charging or variable turbine geometry. At the Institute for Combustion Engines (VKA) at RWTH Aachen University another alternative, the variable compressor pre swirl, was investigated for solving this conflict of aims. Based on theoretical fundamentals the potentials of a variable compressor pre swirl for transient response, low end torque, specific power output and fuel consumption were presented. These theoretical potentials were explored on turbocharger -, engine - and vehicle test bench. An extended compressor map with partial higher compressor efficiency of up to 2% was detected. The outcome of this is an increase of up to 6% in low end torque, found on engine test bench. This effect could also be validated in 1D simulation.

Based on the TurboDISI engine presented earlier [1], [2], a new Spray Guided Turbo (SGT) concept with enhanced engine performance was developed. The turbocharged engine was modified towards utilizing a spray-guided combustion system with a central piezo injector location. Higher specific power and torque levels were achieved by applying specific design and cooling solutions. The engine was developed utilizing a state-of-the-art newly developed charge motion design (CMD) process in combination with single cylinder investigations. The engine control unit has a modular basis and is realized using rapid prototyping hardware. Additional fuel consumption potentials can be achieved with high load EGR, use of alternative fuels and a hybrid powertrain. The CO2 targets of the EU (120 g/km by 2012 in the NEDC) can be obtained with a mid-size vehicle applying the technologies presented within this paper.

In view of limited crude oil resources, alternative fuels for internal combustion engines are currently being intensively researched. Synthetic fuels from natural gas offer a promising interim option before the development of CO2-neutral fuels. Up to a certain degree, these fuels can be tailored to the demands of modern engines, thus allowing a concurrent optimization of both the engine and the fuel. This paper summarizes investigations of a Gas-To-Liquid (GTL) diesel fuel in a modern, post-EURO 4 compliant diesel engine. The focus of the investigations was on power output, emissions performance and fuel economy, as well as acoustic performance, in comparison to a commercial EU diesel fuel. The engine investigations were accompanied by injection laboratory studies in order to assist in the performance analyses.

The high-speed Dl-diesel engine has made a significant advance since the beginning of the 90's in the Western European passenger car market. Apart from the traditional advantage in fuel economy, further factors contributing to this success have been significantly improved performance and power density, as well as the permanent progress made in acoustics and comfort. In addition to the efforts to improve efficiency of automotive powertrains, the requirement for cleaner air increases through the continuous worldwide restriction of emissions by legislative regulations for diesel engines. Against the backdrop of global climate change, significant reduction of CO2 is observed. Hence, for the future, engine and vehicle concepts are needed, that, while maintaining the well-established attractive market attributes, compare more favorably with regard to fuel consumption.

Due to the complex powertrain layout in hybrid vehicles, different configurations concerning internal combustion engine, electric motor and transmission can be combined - as is demonstrated by currently produced hybrid vehicles ([1], [2]). At the Institute for Combustion Engines (VKA) at RWTH Aachen University a combination of simulation, Design of Experiments (DoE) and numerical optimization methods was used to optimize the combustion engine, the powertrain configuration and the operation strategy in hybrid powertrains. A parametric description allows a variation of the main hybrid parameters. Parallel as well as power-split hybrid powertrain configurations were optimized with regard to minimum fuel consumption in the New European Driving Cycle (NEDC). Besides the definition of the optimum configuration for engine, powertrain and operation strategy this approach offers the possibility to predict the fuel consumption for any modifications of the hybrid powertrains.