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A range extended electric vehicle (REEV) has the benefit of zero pipeline emission for most of the daily commute driving using the full electric mode while maintaining the capability for a long-range trip without the requirement of stop-and-charge. This capability is provided by the on-board auxiliary power unit (APU) which is used to maintain the battery state of charge at a minimum limit. Due to the limited APU package size, a small capacity engine with low-cylindercount is normally used which inherently exposes more severe torque pulsation, that arises from a low firing frequency. By using vector control, it is feasible to vary the generator in-cycle torque to counteract the engine torque oscillation dynamically. This allows for a smoother operation of the APU with the possibility of reducing the size of the engine flywheel. In this paper, a series of motor/generator control torque patterns were applied with the aim of cancelling the engine in-cycle torque pulses.

Exhaust Gas Recirculation (EGR) is widely used in IC combustion engines for diluting air intake charge and controlling NOx emission. The rate of EGR required by an engine varies by the speed and load and control of the right amount entering the cylinders is crucial to ensure good engine performance and low NOx emission. However, controlling the amount of EGR entering the intake manifold does not ensure that EGR rate will be evenly distributed among the engine's cylinders. This can many times lead to cylinders operating at very high or low EGR rates which contradictory can deteriorate particulate matter and NOx emission. The present study analyses the cylinder-to-cylinder EGR dispersion of a 4 cylinder 2.2L EUROV Diesel engine and its effects on the combustion stability. A 1D-3D coupling simulation is performed using GT-Power and STAR-CCM+ to analyze the effects of intake manifold geometry and EGR supply configuration on the EGR homogeneity and cylinder-to-cylinder distribution.

The adoption of two stage serial turbochargers in combination with internal combustion engines can improve the overall efficiency of powertrain systems. In conjunction with the increase of engine volumetric efficiency, two stage boosting technologies are capable of improving torque and pedal response of small displacement engines. In two stage sequential systems, high pressure (HP) and low pressure (LP) turbochargers are packaged in a way that the exhaust gases access the LP turbine after exiting the HP turbine. On the induction side, fresh air is compressed sequentially by LP and HP compressors. The former is able to deliver elevated pressure ratios, but it is not able to highly compressor low flow rates of air. The latter turbo-machine can increase charge pressure at lower mass air flow and be by-passed at high rates of air flow.

A supercharger system which boosts the engine via a direct drive from the engine crankshaft has been identified as a possible solution to improve low-end torque and transient response for a conventional turbocharged SI engine. However, the engine equipped with a fixed-ratio supercharger is not as fuel-efficient especially at high load and low speed due to the fact that a large portion of the intake mass air flow has to recirculate through a bypass valve causing inevitable mechanical and flow losses. In addition, the fixed drive ratio of the supercharger which is mainly determined by the full-load requirements might not be able to provide sufficient over-boost during a transient. The fact that a clutch may be necessary for high engine speed operation on the fixed-ratio supercharger system is another issue from the perspective of cost and NVH performance.

The paper discusses investigations into improving the full-load and transient performance of the Ultraboost extreme downsizing engine by the application of the SuperGen variable-speed centrifugal supercharger. Since its output stage speed is decoupled from that of the crankshaft, SuperGen is potentially especially attractive in a compound pressure-charging system. Such systems typically comprise a turbocharger, which is used as the main charging device, compounded at lower charge mass flow rates by a supercharger used as a second boosting stage. Because of its variable drive ratio, SuperGen can be blended in and out continuously to provide seamless driveability, as opposed to the alternative of a clutched, single-drive-ratio positive-displacement device. In this respect its operation is very similar to that of an electrically-driven compressor, although it is voltage agnostic and can supply other hybrid functionality, too.

After years of study and improvement, turbochargers in passenger cars now generally have very high efficiency. This is advantageous, but on the other hand, due to their high efficiency, only a small portion of the exhaust energy is needed for compressing the intake air, which means further utilization of waste heat is restricted. From this point of view, a turbo-compounding arrangement has significant advantage over a turbocharger in converting exhaust energy as it is immune to the upper power demand limit of the compressor. However, with the power turbine being located in series with the main turbine, power losses are incurred due to the higher back pressure which increases the pumping losses. This paper evaluates the effectiveness that the turbo-compounding arrangement has on a 2.0 litres gasoline engine and seeks to draw a conclusion on whether the produced power is sufficient to offset the increased pumping work.

Pressure and temperature levels within a modern internal combustion engine cylinder have been pushing to the limits of traditional materials and design. These operative conditions are due to the stringent emission and fuel economy standards that are forcing automotive engineers to develop engines with much higher power densities. Thus, downsized, turbocharged engines are an important technology to meet the future demands on transport efficiency. It is well known that within downsized turbocharged gasoline engines, thermal management becomes a vital issue for durability and combustion stability. In order to contribute to the understanding of engine thermal management, a conjugate heat transfer analysis of a downsized gasoline piston engine has been performed. The intent was to study the design possibilities afforded by the use of the Selective Laser Melting (SLM) additive manufacturing process.

The Divided Exhaust Period (DEP) concept is an approach which has been proved to significantly reduce the averaged back pressure of turbocharged engines whilst still improving its combustion phasing. The standard layout of the DEP system comprises of two separately-functioned exhaust valves with one valve feeding the blow-down pulse to the turbine whilst the other valve targeting the scavenging behaviour by bypassing the turbine. Via combining the characteristics of both turbocharged engines and naturally aspirated engines, this method can provide large BSFC improvement. The DEP concept has only been applied to single-stage turbocharged engines so far. However, it in its basic form is in no way restricted to a single-stage system. This paper, for the first time, will apply DEP concept to a regulated two-stage (R2S) downsized SI engine.

Engines equipped with pressure charging systems are more prone to knock partly due the increased intake temperature. Meanwhile, turbocharged engines when operating at high engine speeds and loads cannot fully utilize the exhaust energy as the wastegate is opened to prevent overboost. The turboexpansion concept thus is conceived to reduce the intake temperature by utilizing some otherwise unexploited exhaust energy. This concept can be applied to any turbocharged engines equipped with both a compressor and a turbine-like expander on the intake loop. The turbocharging system is designed to achieve maximum utilization of the exhaust energy, from which the intake charge is over-boosted. After the intercooler, the turbine-like expander expands the over-compressed intake charge to the required plenum pressure and reduces its temperature whilst recovering some energy through the connection to the crankshaft.

Current turbocharger models are based on characteristic maps derived from experimental measurements taken under steady conditions on dedicated gas stand facility. Under these conditions heat transfer is ignored and consequently the predictive performances of the models are compromised, particularly under the part load and dynamic operating conditions that are representative of real powertrain operations. This paper proposes to apply a dynamic mathematical model that uses a polynomial structure, the Volterra Series, for the modelling of the turbocharger system. The model is calculated directly from measured performance data using an extended least squares regression. In this way, both compressor and turbine are modelled together based on data from dynamic experiments rather than steady flow data from a gas stand. The modelling approach has been applied to dynamic data taken from a physics based model, acting as a virtual test cell.

When evaluating the performance of new boosting hardware, it is a challenge to isolate the heat transfer effects inherent within measured turbine and compressor efficiencies. This work documents the construction of a lumped mass turbocharger model in the MatLab Simulink environment capable of predicting turbine and compressor metal and gas outlet temperatures based on measured or simulated inlet conditions. A production turbocharger from a representative 2.2L common rail diesel engine was instrumented to enable accurate gas and wall temperature measurements to be recorded under a variety of engine operating conditions. Initially steady-state testing was undertaken across the engine speed and load range in order that empirical Reynolds-Nusselt heat transfer relationships could be derived and incorporated into the model. Steady state model predictions were validated against further experimental data.

Fuel efficiency and torque performance are two major challenges for highly downsized turbocharged engines. However, the inherent characteristics of the turbocharged SI engine such as negative PMEP, knock sensitivity and poor transient performance significantly limit its maximum potential. Conventional ways of improving the problems above normally concentrate solely on the engine side or turbocharger side leaving the exhaust manifold in between ignored. This paper investigates this neglected area by highlighting a novel means of gas exchange process. Divided Exhaust Period (DEP) is an alternative way of accomplishing the gas exchange process in turbocharged engines. The DEP concept engine features two exhaust valves but with separated function. The blow-down valve acts like a traditional turbocharged exhaust valve to evacuate the first portion of the exhaust gas to the turbine.

The paper discusses the concept, design and final results from the ‘Ultra Boost for Economy’ collaborative project, which was part-funded by the Technology Strategy Board, the UK's innovation agency. The project comprised industry- and academia-wide expertise to demonstrate that it is possible to reduce engine capacity by 60% and still achieve the torque curve of a modern, large-capacity naturally-aspirated engine, while encompassing the attributes necessary to employ such a concept in premium vehicles. In addition to achieving the torque curve of the Jaguar Land Rover naturally-aspirated 5.0 litre V8 engine (which included generating 25 bar BMEP at 1000 rpm), the main project target was to show that such a downsized engine could, in itself, provide a major proportion of a route towards a 35% reduction in vehicle tailpipe CO2 on the New European Drive Cycle, together with some vehicle-based modifications and the assumption of stop-start technology being used instead of hybridization.

Increasingly stringent regulations and rising fuel costs require that automotive manufacturers reduce their fleet CO2 emissions. Gasoline engine downsizing is one such technology at the forefront of improvements in fuel economy. As engine downsizing becomes more aggressive, normal engine operating points are moving into higher load regions, typically requiring over-fuelling to maintain exhaust gas temperatures within component protection limits and retarded ignition timings in order to mitigate knock and pre-ignition events. These two mechanisms are counterproductive, since the retarded ignition timing delays combustion, in turn raising exhaust gas temperature. A key process being used to inhibit the occurrence of these knock and pre-ignition phenomena is cooled exhaust gas recirculation (EGR). Cooled EGR lowers temperatures during the combustion process, reducing the possibility of knock, and can thus reduce or eliminate the need for over-fuelling.

Vehicle start-stop systems are becoming increasingly prevalent on internal combustion engine (ICE) because of the capability to reduce emissions and fuel consumption in a cost effective manner. Thus, the ICE undergoes far more starting events, therefore, the behaviour of ICE during start-up becomes critical. In order to simulate and optimise the engine start, Model in the Loop (MiL) simulation approach was selected. A proceduralised cranking test has been carried out on a 2.0-liter turbocharged, gasoline direct injection (GDI) engine to collect data. The engine behaviour in the first 15 seconds was split into eight different phases and studied. The engine controller and the combustion system were highly transient and interactive. Thus, a controller model that can set accurate boundary conditions is needed. The relevant control functions of throttle opening and spark timing have been implemented in Matlab/Simulink to simulate the behaviours of the controller.

A large proportion of automotive engineering research is focused on the reduction of vehicle fuel consumption thereby reducing CO₂ emissions. One effective method is to use an electric motor in conjunction with the engine (hybrid electric vehicle). This paper details the development and performance characteristics of a low cost hybrid vehicle electric motor, originally developed for the retrofit hybrid vehicle market, although it is intended to be suitable for many applications. The motor is a low cost, scalable, high performance motor, primarily for automotive applications. The motor has been designed to make it stackable for higher power or torque requirements. The use of lightweight materials and innovative cooling designs are novel to this motor. Results obtained from extensive testing of the motor are detailed in the paper including the efficiency map, power and torque curves, continuous powers, etc.

The octane appetite of an SI engine can be expressed in terms of an Octane Index: OI = (1−K) RON + K MON where K is a constant for a given operating condition and depends only on the pressure and temperature variation in the engine (it is not a property of the fuel). Experimental measurements of K values can be costly and time consuming. This paper reports the development of a new K-value simulation method that can be applied to any spark ignition engine given basic engine data. Good agreement between simulation and experimental results suggests the method is reliable and can be applied to a wide range of engines.

Engine thermal management systems (TMS) are gaining importance in engine development and calibration to achieve low fuel consumption and meet future emissions standards. To benefit from their full potential, a thorough understanding of the effects on engine behavior is necessary. Steady state tests were performed on a 2.0L direct injection diesel engine at different load points. A design of experiments (DoE) approach was used to conduct exhaust gas recirculation (EGR) and injection timing swings at different coolant temperatures. The effect of the standard engine controller and calibration was observed during these tests. The injection timing strategy included a significant dependency on coolant temperature, retarding injection by about 3° crank angle between coolant temperatures of 70°C and 86°C. In contrast, EGR strategy was essentially independent of coolant temperature, though physical interactions were present due in part to the EGR cooler.

Hybrid drivetrain systems are becoming increasingly prevalent in Automotive and Commercial Vehicle applications and have also been introduced for the 2009 Formula1 motorsport season. The F1 development has the clear intent of directing technical development in motorsport to impact the key issue of fuel efficiency in mainstream vehicles. In order to promote all technical developments, the type of system (electrical, mechanical, hydraulic, etc) for the F1 application has not been specified. A significant outcome of this action is renewed interest and development of mechanical hybrid systems comprising a high speed composite flywheel and a full-toroidal traction drive Continuously Variable Transmission (CVT). A flywheel based mechanical hybrid has few system components, low system costs, low weight and dispenses with the energy state changes of electrical systems producing a highly efficient and power dense hybrid system.

Increasing the number of cold-start engine cycles which could be run in any one day would greatly improve the productivity of an engine test facility. However with the introduction of forced cooling procedures there is the inherent risk that test-to-test repeatability will be affected. Therefore an investigation into the effects caused by forced cooling on fuel consumption and the temperature distribution through the engine and fluids is essential. Testing was completed on a 2.4 litre diesel engine running a cold NEDC. The test facility utilises a basic ventilation system, which draws in external ambient air, which is forced past the engine and then drawn out of the cell. This can be supplemented with the use of a spot cooling fan. The forced cool down resulted in a much quicker cool down which was further reduced with spot cooling, in the region of 25% reduction.