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Technical Paper

A Study of Alcohol Blended Fuels in an Unthrottled Single Cylinder Spark Ignition Engine

This work involved study of the effects of alcohol blends on combustion, fuel economy and emissions in a single cylinder research engine equipped with a mechanical fully variable valvetrain on the inlet and variable valve timing on the exhaust. A number of splash blends of gasoline, iso-octane, ethanol and butanol were examined during port fuel injected early inlet valve closing operation, both with and without variable valve timing. Under low valve overlap conditions, it was apparent that the inlet valve durations/lifts required for full unthrottled operation were remarkably similar for the wide range of blends studied. However, with high valve overlap differences in burning velocities and internal EGR tolerances warranted changes in these valve settings.
Technical Paper

Development of a Fully Variable Compressor Map Enhancer for Automotive Application

Since the agreement to reduce average new car CO2 emissions to 140g/km by 2008, fuel consumption improvement has been one of the main drivers for engine development within the automotive industry. Numerous technologies to reduce vehicle fuel consumption have been investigated, with gasoline engine downsizing being shown as one of the most promising technologies for immediate implementation. In order to achieve further fuel economy gains more aggressive levels of downsizing are being pursued, increasing the requirements for broader and higher pressure ratio compressor maps. The currently reported work shows the development of a fully variable compressor map enhancer, which has the ability to provide both positive and negative pre-whirl. The effect of the map enhancer is shown on both the surge and choke margin of the compressor map when tested on a turbocharged gasoline engine.
Technical Paper

Pre Versus Post Compressor Supply of Cooled EGR for Full Load Fuel Economy in Turbocharged Gasoline Engines

The work was concerned with applying cooled EGR for improved high load fuel economy and reduced pollutant emissions in a turbocharged gasoline engine. While the thermodynamic benefits of EGR were clear, challenges remain to bring the technique to market. A comparison of pre and post compressor EGR supply indicated that post-compressor routing allowed higher compressor efficiencies to be maintained and hence reduced compressor work as the mass flow of EGR was increased. However, with this post-compressor routing, attaining sufficient EGR rate was not possible over the required operating map. Furthermore, at higher engine speeds where the pre-turbine exhaust pressure was greater than the intake plenum pressure, the timing of peak in-cylinder pressure was not as readily advanced towards the optimum.
Journal Article

A Study of Gasoline-Alcohol Blended Fuels in an Advanced Turbocharged DISI Engine

This work was concerned with evaluation of the performance and emissions of potential future biofuels during advanced spark ignition engine operation. The fuels prepared included three variants of gasoline, three gasoline-ethanol blends and a gasoline-butanol fuel altogether covering a range of oxygen mass concentrations and octane numbers to identify key influencing parameters. The combustion of the fuels was evaluated in a turbocharged multi-cylinder direct fuel injection research engine equipped with a standard three-way catalyst and an external EGR circuit that allowed use of either cooled or non-cooled EGR. The engine operating effects studied at both part and boosted high load conditions included fuel injection timing and pressure, excess air tolerance, EGR tolerance and spark retard limits. A number of blends were also mapped at suitable sites across the European drive cycle under downsized engine conditions.
Journal Article

Water Cooled Exhaust Manifold and Full Load EGR Technology Applied to a Downsized Direct Injection Spark Ignition Engine

Gasoline engine downsizing is one of the main technologies being used to reduce automotive fleet CO₂ emissions. However, the shift in operating point to higher loads which goes with aggressive downsizing means that real-world fuel economy can be affected by the amount of over-fuelling required to maintain exhaust gas temperatures within acceptable limits. In addition there is a drive to lower the exhaust gas temperature limit in order to reduce the material costs required for high temperature operation. A water-cooled exhaust manifold is one technology, which can be used to minimize the over-fuelling region. This paper investigates the effects of this technology applied to a twin-charger 1.4-liter gasoline direct injection engine. Data is presented which quantifies the benefits in conjunction with other downsizing technologies including cooled EGR and variable geometry turbochargers.
Journal Article

A Turbulent Jet Ignition Pre-Chamber Combustion System for Large Fuel Economy Improvements in a Modern Vehicle Powertrain

Turbulent Jet Ignition is an advanced pre-chamber initiated combustion system for an otherwise standard spark ignition engine found in current on-road vehicles. This next-generation pre-chamber design overcomes previous packaging obstacles by simply replacing the spark plug in a modern four-valve, pent roof spark ignition engine. Turbulent Jet Ignition enables very fast burn rates due to the ignition system producing multiple, distributed ignition sites, which consume the main charge rapidly and with minimal combustion variability. The fast burn rates allow for increased levels of dilution (lean burn and/or EGR) when compared to conventional spark ignition combustion, with dilution levels being comparable to other low temperature combustion technologies (homogeneous charge compression ignition - HCCI) without the complex control drawbacks.
Journal Article

Development of a Turbocharged Direct Injection Downsizing Demonstrator Engine

This paper describes the initial development of a 3 cylinder 1.2l technology demonstrator engine from MAHLE. The purpose of this highly turbocharged direct injection engine is to demonstrate production-ready technologies that enable low CO2 emissions via downsizing by 50%. Downsizing is one of the most proven paths to CO2 emission reduction. By using careful design, a 2.4 l engine can be replaced by a 1.2l engine that has superior torque at all speeds and on-road fuel consumption benefits of 25 - 30%. A two-stage turbocharging system has been developed for the engine to enable good transient response and the high torque levels at all engine speeds demanded by a downsizing approach. Several options were tested and the final system exceeds the 30bar peak BMEP target with stoichiometric fuelling. Indeed, lambda = 1.0 fuelling is maintained over the majority of the full-load line and the 144kW peak power requirement is fulfilled at only 6000 rpm.