Search Results

The paper discusses the concept, specification and performance of a new, dedicated range extender engine for plug-in series hybrid vehicles conceived and designed by Lotus Engineering. This has been undertaken as part of a consortium project called Limo Green, part-funded by the UK government. The Lotus Range Extender engine has been conceived from the outset specifically as an engine for a plug-in series hybrid vehicle, therefore being free of some of the constraints placed on engines which have to mate to conventional, stepped mechanical transmissions. The paper starts by defining the philosophical difference between an engine for range extension and an engine for a full series hybrid vehicle, a distinction which is important with regard to how much power each type must produce. As part of this, the advantages of the sparkignition engine over the diesel are outlined.

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.

Iso-stoichiometric ternary blends - in which three-component blends of gasoline, ethanol and methanol are configured to the same stoichiometric air-fuel ratio as an equivalent binary ethanol-gasoline blend - can function as invisible "drop-in" fuels suitable for the existing E85/gasoline flex-fuel vehicle fleet. This has been demonstrated for the two principal means of detecting alcohol content in such vehicles, which are considered to be a virtual, or software-based, sensor, and a physical sensor in the fuel line. Furthermore when using such fuels the tailpipe CO₂ emissions are essentially identical to those found when the vehicle is operated on E85. Because of the fact that methanol can be made from a wider range of feed stocks than ethanol and at a cheaper price, these blends then provide opportunities to improve energy security, to reduce greenhouse gas emissions and to produce a fuel blend which could potentially be cheaper on a cost-per-unit-energy basis than gasoline or diesel.

The engine of a high performance sports car has been converted to operation on E85, a high alcohol-blend fuel containing nominally 85% ethanol and 15% gasoline by volume. In addition to improving performance, the conversion resulted in significant improvement in full-load thermal efficiency versus operation on gasoline. This engine has been fitted in a test vehicle and made flex-fuel capable, a process which resulted in significant improvements in both vehicle performance and tailpipe CO2 when operating solely on ethanol blends, offering an environmentally-friendly approach to high performance motoring. The present paper describes some of the highlights of the development of the flex-fuel calibration to enable the demonstrator vehicle to operate on any mixture of 95 RON gasoline and E85 in the fuel tank. It also discusses how through detailed development, the vehicle has been made to comply with primary pollutant emissions legislation on any ethanol-gasoline mixture up to E85.

The paper discusses the use of alcohol fuels in high performance pressure-charged engines such as are typical of the type being developed under the ‘downsizing’ banner. To illustrate this it reports modifications to a supercharged high-speed sports car engine to run on an ethanol-based fuel (ethanol containing 15% gasoline by volume, or ‘E85’). The ability for engines to be able to run on alcohol fuels may become very important in the future from both a global warming viewpoint and that of security of energy supply. Additionally, low-carbon-number alcohol fuels such as ethanol and methanol are attractive alternative fuels because, unlike gaseous fuels, they can be stored relatively easily and the amount of energy that can be contained in the vehicle fuel tank is relatively high (although still less than when using gasoline).

Omnivore is a single cylinder spark ignition based research engine conceived to maximize the operating range of auto-ignition on a variety of fossil and renewable fuels. In order to maximize auto-ignition operation, the two-stroke cycle was adopted with two independent mechanisms for control. The charge trapping valve system is incorporated as a means of varying the quantity of trapped residuals whilst a variable compression ratio mechanism is included to give independent control over the end of compression temperature. The inclusion of these two technologies allows the benefits of trapped residual gas to be maximised (to minimize NOx formation) whilst permitting variation of the onset of auto-ignition. 2000rpm and idle are the main focus of concern whilst also observing the influence of injector location. This paper describes the rational behind the engine concept and presents the results achieved at the time of writing using 98ulg and E85 fuels.

The paper critiques proposals for de-carbonizing transport and offers a potential solution which may be attained by the gradual evolution of the current fleet of predominantly low-cost vehicles via the development of carbon-neutral liquid fuels. The closed-carbon cycles which are possible using such fuels offer the prospect of maintaining current levels of mobility with affordable transport whilst neutralizing the threat posed by the high predicted growth of greenhouse gas emissions from this sector. Approaches to de-carbonizing transport include electrification and the adoption of molecular hydrogen as an energy carrier. These two solutions result in very expensive vehicles for personal transport which mostly lie idle for 95% of their life time and are purchased with high-cost capital.

The purpose of the European « SPACE LIGHT » (Whole SPACE combustion for LIGHT duty diesel vehicles) 3-year project launched in 2001 is to research and develop an innovative Homogeneous internal mixture Charged Compression Ignition (HCCI) for passenger cars diesel engine where the combustion process can take place simultaneously in the whole SPACE of the combustion chamber while providing almost no NOx and particulates emissions. This paper presents the whole project with the main R&D tasks necessary to comply with the industrial and technical objectives of the project. The research approach adopted is briefly described. It is then followed by a detailed description of the most recent progress achieved during the tasks recently undertaken. The methodology adopted starts from the research study of the in-cylinder combustion specifications necessary to achieve HCCI combustion from experimental single cylinder engines testing in premixed charged conditions.

Designers are under increasing pressure to provide powertrain systems which meet tougher market and legislative requirements for:- performance, emissions and economy reliability and durability noise and refinement To meet increasing competition, powertrain products need to be “fast to market and right first time”. This implies the evolution of existing technology, comprising multicylinder reciprocating engines and gear transmissions, drawing on a database of decades of powerplant design experience. It is with this background that CAE has proven engineering value supporting key areas of powertrain engineering to meet these technological challenges in a cost effective and timely manner. This paper follows the analytical engineering of a typical component, the exhaust system. Particular emphasis is given to the manifold and downpipe components which duct gas from the cylinder head to the catalyst.

The paper presents vehicle-based test work using tri-component, or ternary, blends of gasoline, ethanol and methanol for which the stoichiometric air-fuel ratio (AFR) was controlled to be 9.7:1. This is the same as that of conventional "E85" alcohol-based fuel. Such ternary blends are termed "GEM" after the first initial of the three components. The present work was a continuation of an earlier successful project which established that the blends were effectively invisible to a car using a virtual alcohol sensor. The vehicle used here employed the other major technology in flex-fuel vehicles to determine the proportion of alcohol fuel in the tank, a physical alcohol sensor. Another aspect of the present work included the desire to investigate ternary blend replacements for E85 having low ethanol concentrations. Evidence from the previous work suggested that under specific conditions, ethanol was required in some amount to act as a cosolvent for the gasoline and methanol in the blend.

The paper presents the concept of ternary blends of gasoline, ethanol and methanol in which the stoichiometric air-fuel ratio (AFR) is controlled to be 9.7:1, the same as that of conventional ‘E85’ alcohol-based fuel. This makes them iso-stoichiometric. Such blends are termed ‘GEM’ after the first initial of the three components. Calculated data is presented showing how the volumetric energy density relationship between the three components in these blends changes as the stoichiometric AFR is held constant but ethanol content is varied. From this data it is contended that such GEM blends can be ‘drop-in’ alternatives to E85, because when an engine is operated on any of these blends the pulse widths of the fuel injectors would not change significantly, and so there will be no impact on the on-board diagnostics from the use of such blends in existing E85/gasoline flex-fuel vehicles.

Five different fuels, including gasoline, commercial E85, pure methanol and two mixtures of gasoline, ethanol and methanol, (GEM), configured to a target stoichiometric air fuel ratio have been investigated in a fully-optically-accessed engine. The work investigated effects of injection duration, and performed spray imaging, thermodynamic analysis of the combustion and OH imaging, for two fixed engine conditions of 2.7 and 3.7 bar NMEP at 2000 rpm. The engine was operated with constant ignition timing for all fuels and both loads. One of the most important results from this study was the suitability of a single type of injector to handle all the fuels tested. There were differences observed in the spray morphology between the fuels, due to the different physical properties of the fuels. The energy utilisation measured in this study showed differences of up to 14% for the different GEM fuels whereas an earlier in-vehicle study had showed only 2 to 3%.

There is a great deal of interest in new technologies to assist in reducing the CO2 output of passenger vehicles, as part of the drive to meet the limits agreed by the EU and the European Automobile Manufacturer's Association ACEA, itself a result of the Kyoto Protocol. For the internal combustion engine, the most promising of these include gasoline direct injection, downsizing and fully variable valve trains. While new types of spray-guided gasoline direct injection (GDI) combustion systems are finally set to yield the level of fuel consumption improvement which was originally promised for the so-called ‘first generation’ wall- and air-guided types of GDI, injectors for spray-guided combustion systems are not yet in production to help justify the added complication and cost of the NOx trap necessary with a stratified combustion concept.

Experience has shown that a vehicle equipped with Active suspension and rear wheel steering can be a very powerful tool for research into vehicle dynamics. Passive or “adaptiveu vehicle suspension systems can be emulated. This has considerable potential for shortening vehicle development times. Active systems provide the ability to separate dynamic modes from one another. This enables detailed examination of each effect without the cross coupling normally experienced with passive vehicles. The driver is an important part of the dynamic loop and ultimately it is he/she who must be able to control the vehicle with confidence, precision, and minimum fatigue. An Active vehicle is a powerful way to investigate the feedback and cues needed by the driver, and to produce objective requirements to achieve them. Thus armed, vehicle design, computer simulation and development functions can be more effective in getting better products more quickly to the market.

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.

Hybrid electric vehicles offer significant fuel economy benefits, because battery and fuel can be used as complementing energy sources. This paper presents the use of dynamic programming to find the optimal blend of power sources, leading to the lowest fuel consumption and the lowest level of harmful emissions. It is found that the optimal engine behavior differs substantially to an on-line adaptive control system previously designed for the Lotus Evora 414E. When analyzing the trade-off between emission and fuel consumption, CO and HC emissions show a traditional Pareto curve, whereas NOx emissions show a near linear relationship with a high penalty. These global optimization results are not directly applicable for online control, but they can guide the design of a more efficient hybrid control system.

A Consortium of steel producing organizations has been working to reduce the mass of automobiles. An initiative identified as ULSAS (UltraLight Steel Automotive Suspension) is in progress which considers automotive rear suspension systems. The programme has evaluated and established the current status of material and process technology utilization and its application to rear suspension systems. Extensive studies have generated over fifty five design ideas which provide an indication of the potential opportunities for performance improvement that could be realised through the focused application of steel technologies. Work is in progress developing these ideas and quantifying the performance improvements.