Search Results

The aggressive reduction of future diesel engine NOx emission limits forces the heavy- and light-duty diesel engine manufacturers to develop means to comply with stringent legislation. As a result, different exhaust emission control technologies applicable to NOx have been the subject of many investigations. One of these systems is the NOx adsorber catalyst, which has shown high NOx conversion rates during previous investigations with acceptable fuel consumption penalties. In addition, the NOx adsorber catalyst does not require a secondary on-board reductant. However, the NOx adsorber catalyst also represents the most sulfur sensitive emissions control device currently under investigation for advanced NOx control. To remove the sulfur introduced into the system through the diesel fuel and stored on the catalyst sites during operation, specific regeneration strategies and boundary conditions were investigated and developed.

The Yuchai F-6113 is an inline 6-cylinder heavy duty Diesel engine, mainly for truck application with a displacement of 8.4 liters and a rated power of 258 kW. It was derived from the F-6108 with a displacement of 7.3 liters. The boundary conditions for the new crankcase were set by the existing machining line. Substantially increasing the bore diameter while keeping the bore pitch constant, was achieved by replacing the conventional top stop liner with a mid stop liner with open deck. This liner concept is rather unique for heavy duty truck engines. The two 2-valve cylinder heads, covering 3 cylinders each, were replaced by a 4-valve one-piece cylinder head. The design comprises an electronically controlled Unit Pump Injection System (UPS) with the alternative to use an inline injection pump. The engine structure was laid out for the high specific output and the peak cylinder pressure requirements for the compliance with Euro III emission legislation.

The European research co-operation Lotus is presented. The main objectives of the project were i) to show the potential for a urea-based SCR system to comply with the EU standard of years 2005 and 2008 for heavy-duty Diesel engines for different driving conditions with optimal fuel consumption, ii) to reach 95 % conversion of NOx at steady state at full load on a Euro III engine, iii) to reach 75 % NOx reduction for exhaust temperatures between 200-300°C, and 85 % average NOx reduction between 200-500°C. The energy content of the consumed urea should not exceed 1.0 %, calculated as specific fuel consumption. These targets were met in May 2003 and the Lotus SCR system fulfilled the Euro V NOx legislative objectives for year 2008.

Beside the traditional prediction of stresses and verification by mechanical testing the optimization of cylinder liner bore distortion is one of today's most important topics in crankcase structure development. Low bore distortion opens up potentials for optimizing the piston group. As the piston rings achieve better sealing characteristics in a low deformation cylinder liner, oil consumption and blow-by are reduced. For unchanged oil consumption and blow-by demands, engine friction and subsequently, fuel consumption could be reduced by decreasing the pre-tension of the piston rings. From the acoustical point of view an optimization of piston-slap noise is often based on an optimized bore distortion behavior. Apart from basics to the behavior of liner bore distortion the paper presents advanced analytical and empirical methods for detailed prediction, verification and optimization of bore distortion taking into account the effective engine operation conditions.

SI engines with gasoline direct injection are currently the focus of development for almost all car manufacturers. After the introduction of DISI engines, first to the Japanese market and after a short time delay also in Europe, a broad variety of technical solutions for efficient stratified concepts can be stated. The targets of the development activities in this field are defined by legislation and customer's demands. The potential reduction of fuel consumption with stratified operation has to be combined with a further improvement of the full load potential of the DISI engine. A substantial part of the development activities are the fulfillment of current and future emission standards. Therefore, in order to realize a highly efficient lean operation, new technologies and strategies in the field of exhaust gas aftertreatment and vehicle application are required.

Environmental concern demands that emissions and fuel consumption of vehicles have to improve considerably in the next 10 years. New technologies for gasoline engines, downsizing with high boosting, direct injection and fully variable valve train systems, are being developed. For Diesel engines, improved components including piezobased injectors and particle filters are expected. In the drive train new starter-generator systems as well as automated manual transmissions are being developed. In parallel alternative fuels are investigated and the use of hybrid drives and fuel cells are developed. This paper reports the progress made in the recent years and gives a comparative assessment on the different technologies with a prediction of the introduction dates and volumes into the market.

Due to today's demands to reduce cost and product time to market, engineering procedures are increasingly using more sophisticated simulation techniques, instead of validation testing. Early implementation of CAE methods yield higher quality products, even with first prototypes, reducing the design iterations required to reach production quality. The strategy is to conduct specific evaluations of a realistic representation of the product while focusing on the key boundary conditions necessary to extract fatigue effects. Discussed in this paper are adequate CAE methods for early identification, evaluation and removal of conceptual and local structural weaknesses. Possible solutions gained from a computational optimization process are discussed for highly loaded HSDI diesel cylinder heads as a representative example.

With regard to increasingly stringent emission legislation natural gas is gaining interest as an alternate fuel. Concerning mobile application natural gas is often considered to produce potentially lower exhaust emissions compared to diesel and gasoline fuel. Nevertheless, also the exhaust gas of diesel and gasoline fuelled vehicles will be improved by applying advanced technical solutions. The paper reveals the state-of-the-art in exhaust emission behaviour of diesel, gasoline, liquified petroleum gas and natural gas fuelled vehicles. Passenger cars and light-duty trucks will be considered as well as HD-trucks. Emissions include NOx, THC, NMHC, CO, Aldehydes and PAH. In addition CH4 and CO2 emissions are discussed with respect to increasing concern about the greenhouse effect. From the viewpoint of the HD-engines the alternate fuels Dimethylether (DME) and Diesel/water-Emulsion are also considered.

The requirements for diesel and gasoline engines are continuously increasing with respect to emissions, fuel consumption and durability. Besides the engine development process the quality of the production engine itself has to be ensured. This paper discusses alternative philosophies and approaches in terms of the quality management process. Based on a detailed analysis of the required equipment advanced solutions are presented. Modular containerized test cells are described being equipped exactly to the current testing task ready to use in low infrastructure. The testing capacity of the facility can be adjusted to the actual production volume by simply removing or adding modular test cells. Thus, at every facility the testing tasks can be executed successfully and the investment can be kept low.

The main goal in the development of new automobile SI engines is to significantly reduce fuel consumption. To this end both, variable valve actuation and direct gasoline injection, are being pursued as new engine concepts. Both approaches appear to offer approximately the same potential to reduce fuel consumption. The development so far is creating the impression of two competing technical concepts with no obvious way to combine them [1]. The two engine concepts, however, can be combined, although it is often objected that their combination would only yield marginal additional potential. That is true to the extent that the advantages of dethrottling offered by both of the concepts can only be counted once in terms of overall potential. But there is a number of additional effects to be taken into account. This Paper represents an analysis of the individual potential of the two approaches as well as an estimation of their combined potential.

The challenge to reduce fuel consumption in S.I. engines is leading to the application of new series production technologies: including direct injection and, recently, the variable valve train, both aiming at unthrottled engine operation. In addition to these technologies, turbo- or mechanical supercharging is of increasing interest because, in principle, it offers a significant potential for improved fuel economy. However, a fixed compression ratio normally leads to a compromise, in that the charged engine is more of a performance enhancement than an improver of fuel economy. Fuel efficient downsizing concepts can be realized through the application of variable compression ratio. In this paper, a variable compression ratio design solution featuring eccentric movement of the crankshaft is described. Special attention is given to the integration of this solution into the base engine.

Fuel properties are always considered as one of the main factors to diesel engines concerning performance and emission discussions. There are still challenges for researchers to identify the most correlating and non-correlating fuel properties and their effects on engine behavior. Statistical analyses have been applied in this study to derive the most un-correlating properties. In parallel, sensitivity analysis was performed for the fuel properties as well as to the emission and performance of the engine. On one hand, two different analyses were implemented; one with consideration of both, non-aromatic and aromatic fuels, and the other were performed separately for each individual fuel group. The results offer a different influence on each type of analysis. Finally, by considering both methods, most common correlating and non-correlating properties have been derived.

The application of technologies such as direct injection, turbo charging and variable valve timing has caused a significant evolution of the gasoline engine with positive effects on fuel consumption and emissions. The current developments are primarily focused on the realization of improved full load characteristics and fuel consumption reduction with stoichiometric operation, following the downsizing approach in combination with turbo charging and high specific power. The requirements of high specific power in a relatively small cylinder displacement and a wide range of DI injection specifications lead to competing development targets and to a high number of degrees of freedom during engine layout and optimization. One of the major targets is to assess the stability of the combustion system in the early development phase.

From current point of view future emission legislations for heavy-duty engines as well as industrial engines will require complex engine internal measures in combination with sophisticated aftertreatment systems as well as according control strategies to reach the emission targets. With EU VI, JP 09/NLT and US10 for heavy-duty engines as well as future Tier4 final or stage IV emission legislation for industrial applications, EGR + DPF + SCR probably will be combined for most applications and therefore quite similar technological approaches will be followed up in Europe as well as in the US and in Japan. Most “emerging markets” all over the world follow up the European, US or Japanese emission legislation with a certain time delay. Therefore similar technologies need to be introduced in these markets in the future. On the other hand specific market boundary conditions and requirements have to be considered for the development of tailored system concepts in these markets.

Both, the continuous strengthening of the exhaust emission legislation and the striving for a substantial reduction of the carbon dioxide output in the traffic sector depict substantial requirements for the global automotive industry and especially for the engine manufacturers. From the multiplicity of possible approaches and strategies for clear compliance with these demands, engine internal measures offer a large and, eventually more important, very economical potential. For example, the achievements in fuel injection technology are a measure which in the last years has contributed significantly to a notable reduction of the emissions of the modern DI Diesel engines at favorable fuel efficiency. Besides the application of modern fuel injection technology, the linked combustion control (Closed Loop Combustion Control) opens possibilities for a further optimization of the combustion process.

Piston rings are faced with a broad range of demands like optimal sealing properties, wear properties and reliability. Even more challenging boundary conditions must be met when latest developments in the fields of direct injection as well as the application of bio fuels. This complex variety of piston ring design requirements leads to the need of a comprehensive simulation model in order to support the development in the early design phase prior to testing. The simulation model must be able to provide classical objectives like friction analysis, wear rate and blow-by. Furthermore, it must include an adequate oil consumption model. The objective of this work is to provide such a simulation model that is embedded in the commercial MBS software ‘FEV Virtual Engine’. The MBS model consists of a cranktrain assembly with a rigid piston that contains flexible piston rings.

Turbocharged DISI engines with four cylinders have established in the market and provide a performance comparable to larger six-cylinder engines in the smaller compartment of a four-cylinder engine. In the Japanese market, also turbo gasoline engines with 500 - 660 cm₃ displacement have a long tradition in Kei-Cars. However, those engines show a lower specific performance as would be required for propelling typical small or compact vehicles in Europe. Recently, two-cylinder turbo engines have come to market, which are found attractive with respect to sound, package, and also enable low vehicle fuel consumption in NEDC test. The paper presents a turbocharger layout study on 2- and 3-cylinder engines. It discusses the influence of cylinder displacement volume on the sizing of turbines and compressors, and how specific flow phenomena in the turbine can be captured in the simulation model.

Injector cleanliness is well characterised in the literature [1,2,3,4] as a key factor for maintained engine performance in modern diesel cars. Injector deposits have been shown to reduce injector flow capacity resulting in power loss under full load; however, deposit effects on fuel economy are less well characterised. A study was conducted with the aim of developing an understanding of the impact of diesel injector nozzle deposits on fuel economy. A series of tests were run using a previously published chassis dynamometer test method. The test method was designed to evaluate injector deposit effects on performance under driving conditions more representative of real world driving than the high intensity test cycle of the industry standard, CEC DW10B engine test, [1]. The efficacy of different additive levels in maintaining injector cleanliness and therefore power and fuel economy was compared in a light duty Euro 5 certified vehicle.

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 current discussion about possible limitation of CO2 emissions makes improvement of fuel consumption a central topic for gasoline engine development. Various technological solutions are available to realize this improvement. Concepts featuring direct fuel injection, engine downsizing and unthrottled control of engine load with variable valvetrains are currently considered the most promising ways to achieve this goal. Further concepts that are under development include Controlled Auto Ignition (CAI) and homogenous lean burn combustion as well as certain combinations of these technologies. Within the European market, direct injection is currently the most popular solution. The drawback is that a very expensive exhaust gas aftertreatment system is necessary to keep exhaust emissions within legal limits.