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The present work investigates a means of controlling engine hydrocarbon startup and shutdown emissions in a Wankel engine which uses a novel rotor cooling method. Mechanically the engine employs a self-pressurizing air-cooled rotor system (SPARCS) configured to provide improved cooling versus a simple air-cooled rotor arrangement. The novelty of the SPARCS system is that it uses the fact that blowby past the sealing grid is inevitable in a Wankel engine as a means of increasing the density of the medium used for cooling the rotor. Unfortunately, the design also means that when the engine is shutdown, due to the overpressure within the engine core and the fact that fuel vapour and lubricating oil are to be found within it, unburned hydrocarbons can leak into the combustion chambers, and thence to the atmosphere via either or both of the intake and exhaust ports.

Particulate emissions from gasoline direct injection (GDI) engines continue to be a topic of substantial research interest. Forthcoming regulation both in the USA and the EU will further reduce their emission and drive innovation. Substantial research effort is spent undertaking experiments to understand, characterize, and research particle number (PN) emissions from engines and vehicles. Recent advances in computing power, data storage, and understanding of artificial intelligence algorithms now mean that these are becoming an important tool in engine research. In this work a random forest (RF) algorithm is used for the prediction of PN emissions from a highly boosted (up to 32 bar BMEP) GDI engine. Particle size, concentration, and the accumulation mode geometric standard deviation (GSD) are all predicted by the model. The results are analysed and an in depth study on parameter importance is carried out.

In a previous study it was shown that a production vehicle employing a Wankel rotary engine, the Mazda RX-8, was easily capable of meeting much more modern hydrocarbon emissions than it had been certified for. It was contended that this was mainly due to its provision of zero port overlap through its adoption of side intake and exhaust ports. In that earlier work a preliminary investigation was conducted to gauge the impact of adopting a zero overlap approach in a peripherally-ported Wankel engine, with a significant reduction in performance and fuel economy being found. The present work builds on those initial studies by taking the engine from the vehicle and testing it on an engine dynamometer. The results show that the best fuel consumption of the engine is entirely in line with that of several proposed dedicated range extender engines, supporting the contention that the Wankel engine is an excellent candidate for that role.

The use of Wankel rotary engines as a range extender has been recognised as an appealing method to enhance the performance of Hybrid Electric Vehicles (HEV). They are effective alternatives to conventional reciprocating piston engines due to their considerable merits such as lightness, compactness, and higher power-to-weight ratio. However, further improvements on Wankel engines in terms of fuel economy and emissions are still needed. The objective of this work is to investigate the engine modelling methodology that is particularly suitable for the theoretical studies on Wankel engine dynamics and new control development. In this paper, control-oriented models are developed for a 225CS Wankel rotary engine produced by Advanced Innovative Engineering (AIE) UK Ltd. Through a synthesis approach that involves State Space (SS) principles and the artificial Neural Networks (NN), the Wankel engine models are derived by leveraging both first-principle knowledge and engine test data.

The Wankel rotary engine historically found limited success in automotive applications due in part to poor combustion efficiency and challenges around emissions. This is despite its significant advantages in terms of power density, compactness, vibrationless operation, and reduced parts count in relation to the 4-stroke reciprocating engine, which is now-dominant in the automotive market. A large part of the reason for the poor fuel economy and high hydrocarbon emissions of the Wankel engine is that there is a very significant amount of overlap when the ports are opened and/or closed by the rotor apices (so-called peripheral ports). This paper investigates the benefits of zero overlap from a production engine with this characteristic and the effect of configuring a peripherally-ported Wankel engine in such a manner.

Reducing emissions from light duty vehicles is critical to meet current and future air quality targets. With more focus on real world emissions from light-duty vehicles, the interactions between engine and exhaust gas aftertreatment are critical. For modern engines, most emissions are generated during the warm-up phase following a cold start. For Diesel engines this is exaggerated due to colder exhaust temperatures and larger aftertreatment systems. The De-NOx aftertreatment can be particularly problematic. Engine manufacturers are required to take measures to address these temperature issues which often result in higher fuel consumption (retarding combustion, increasing engine load or reducing the Diesel air-fuel ratio). In this paper we consider an inner-insulated turbocharger as an alternative, passive technology which aims to reduce the exhaust heat losses between the engine and the aftertreatment. Firstly, the concept and design of the inner-insulated turbocharger is presented.

The gradual push towards electric vehicles (EV) as a primary mode of transport has resulted in an increased focus on electric and hybrid powertrain research. One answer to the consumers’ concern over EV range is the implementation of small combustion engines as generators to supplement the energy stored in the vehicle battery. Since these range extender generators have the opportunity to run in a small operating window, some engine types that have historically struggled in an automotive setting have the potential to be competitive. The relative merits of two different engine options for range extended electric vehicles are simulated in vehicle across the WLTP drive cycle. The baseline electric vehicle chosen was the BMW i3 owing to its availability as an EV with and without a range extender gasoline engine.

Wankel rotary engines are becoming an increasingly popular area of research with regard to their use as a range extender in the next generation of Hybrid Electric Vehicle (HEV). Due to their simple design, lightness, compactness and very favourable power-to-weight ratio, they represent one of the best alternative solutions to classic reciprocating piston engines. On the other hand, current Wankel engines still need improvements in terms of specific fuel consumption and emissions. This paper describes an innovative approach for the assessment of the performance of a modern rotary engine. All the experimental activities will be carried out within the Innovate UK funded ADAPT Intelligent Powertrain project led by Westfield Sportscars Limited.

In recent years, there has been an impetus in the automotive industry to develop newer diesel injection systems with a view to reducing fuel consumption and emissions. This development has led to hardware capable of higher pressures, typically up to 2500 bar. An increase in pressure will result in a corresponding increase in fuel temperature after compression with studies showing changes in fuel temperatures of up to 150 °C in 1000-2500 bar injection systems. Until recently, the addition of Fatty Acid Methyl Esters, FAME, to diesel had been blamed for a number of fuel system durability issues such as injector deposits and fuel filter blocking. Despite a growing acceptance within the automotive and petrochemical industries that FAME is not solely to blame for diesel instability, there is a lack of published literature in the area, with many studies still focusing on FAME oxidation to explain deposit formation and hardware durability.

Fuel economy and emission challenges are pushing automotive OEMs to develop alternative hybrid-electric, and full-electric powertrains. This increases variation in potential powertrain architectures, exacerbating the already complex control software used to coordinate various propulsion devices within the vehicle. Safety of this control software must be ensured through high-integrity software monitoring functions that detect faults and ensure safe mitigating action is taken. With the complexity of the control software, this monitoring functionality has itself become complex, requiring extensive modification for each new powertrain architecture. Significant effort is required to develop, calibrate, and verify to ensure safety (as defined by ISO 26262). But this must also be robust against false fault-detection, thereby maximising vehicle availability to the customer.

Stringent regulations on fuel economy have driven major innovative changes in the internal combustion engine design. (E.g. CAFE fuel economy standards of 54.5 mpg by 2025 in the U.S) Vehicle manufacturers have implemented engine infrastructure changes such as downsizing, direct injection, higher compression ratios and turbo-charging/super-charging to achieve higher engine efficiencies. Fuel properties therefore, have to align with these engine changes in order to fully exploit the possible benefits. Fuel octane number is a key metric that enables high fuel efficiency in an engine. Greater resistance to auto-ignition (knock) of the fuel/air mixture allows engines to be operated at a higher compression ratio for a given quantity of intake charge without severely retarding the spark timing resulting in a greater torque per mass of fuel burnt. This attribute makes a high octane fuel a favorable hydrocarbon choice for modern high efficiency engines that aim for higher fuel economy.

Precise, repeatable and representative testing is a key tool for developing and demonstrating automotive fuel and lubricant products. This paper reports on the first findings of a project that aims to determine the requirements for highly repeatable test methods to measure very small differences in fuel economy and powertrain performance. This will be underpinned by identifying and quantifying the variations inherent to this specific test vehicle, both on-road and on Chassis Dynamometer (CD), that create a barrier to improved testing methods. In this initial work, a comparison was made between on-road driving, the New European Drive Cycle (NEDC) and World harmonized Light-duty Test Cycle (WLTC) cycles to understand the behavior of various vehicle systems along with the discrepancies that can arise owing to the particular conditions of the standard test cycles.

Range Extended Electric Vehicles (REEVs) are gaining popularity due to their simplicity, reduced emissions and fuel consumption when compared to parallel or series/parallel hybrid vehicles. The range extender internal combustion engine (ICE) can be optimised to a number of steady state points which offers significant improvement in overall exhaust emissions. One of the key challenges in such vehicles is to reduce the overall powertrain costs, and OEMs providing REEVs such as the BMW i3 have included the range extender as an optional extra due to increasing costs on the overall vehicle price. This paper discusses the development of a low cost Auxiliary Power Unit (APU) of c.25 kW for a range extender application utilising a 624 cc two cylinder automotive gasoline engine. Changes to the base engine are limited to those required for range extender development purposes and include prototype control system, electronic throttle, redesigned manifolds and calibration on European grade fuel.

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.

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.

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.