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Technical Paper

Two-Cylinder Gasoline Engine Concept for Highly Integrated Range Extender and Hybrid Powertrain Applications

The demand for improved fuel economy and the request for Zero Emission within cities require complex powertrains with an increasing level of electrification already in a short-termed timeframe until 2025. According to general expectations the demand for Mild-Hybrid powertrains will increase significantly within a broad range of implementation through all vehicle classes as well as on electric vehicles with integrated Range Extender (RE) mainly for use in urban areas. Whereas Mild Hybrid Vehicles basically use downsized combustion engines at current technology level, vehicles with a high level of powertrain electrification allow significantly different internal combustion engine (ICE) concepts. At AVL, various engine concepts have been investigated and evaluated with respect to the key criteria for a Range Extender application. A Wankel rotary engine concept as well as an inline 2 cylinder gasoline engine turned out to be most promising.
Journal Article

Development of the Combustion System for a Flexible Fuel Turbocharged Direct Injection Engine

Gasoline turbocharged direct injection (GTDI) engines, such as EcoBoost™ from Ford, are becoming established as a high value technology solution to improve passenger car and light truck fuel economy. Due to their high specific performance and excellent low-speed torque, improved fuel economy can be realized due to downsizing and downspeeding without sacrificing performance and driveability while meeting the most stringent future emissions standards with an inexpensive three-way catalyst. A logical and synergistic extension of the EcoBoost™ strategy is the use of E85 (approximately 85% ethanol and 15% gasoline) for knock mitigation. Direct injection of E85 is very effective in suppressing knock due to ethanol's high heat of vaporization - which increases the charge cooling benefit of direct injection - and inherently high octane rating. As a result, higher boost levels can be achieved while maintaining optimal combustion phasing giving high thermal efficiency.
Technical Paper

Reducing Emissions and Improving Fuel Economy by Optimized Combustion of Alternative Fuels

Alternative fuels, especially fuels based on biological matter, are gaining more and more attention. Not only as a pure substitute of oil but also in terms of a possibility for further reduction in emission and as an option to improve the global CO2 balance. For improving the engine performance (emissions, fuel consumption, torque and drivability) the adjustment of fuel injection, the fuel evaporation process and the combustion process itself is paramount. In order to exploit the full potential of alternative fuels excellent knowledge of the fuel properties, including the impact on ignition and flame propagation, is required. This needs suitable tools for analysis of the fuel injection and combustion process. These tools have to support the optimization of the combustion system and the dynamic engine calibration for lowest emissions and most efficient use of fuel. As the term “Alternative Fuels” covers a very wide area a brief overview on available fuel types will be made.
Technical Paper

Combustion Analysis for In - Vehicle Application

Traditional power train development work is concentrated mainly on test bed and on chassis dyno. Though we can simulate a lot of real world conditions on testbed and chassis dyno today, on road application work willis gaining more attention. This means that strategies and tools for invehicle testing under real world conditions are becoming more important. Emission, performance, fuel economy, combustion noise and driving comfort are linked to combustion quality, i.e. quality of fuel mixture preparation and flame propagation. The known testing and research equipment is only partly or not at all applicable for in-vehicle development work. New tools for on the road testing are required. Following, a general view on in-vehicle power train testing will be given. Additionally, new ways to investigate cylinder and cycle specific soot formation in GDI engines with fiber optic tools will be presented.
Technical Paper

Functional Integration as Key for Affordable Electrified Passenger Car Powertrains

Further fuel efficiency improvements are mandatory in order to achieve the CO2 emission limits envisaged in the future. Electrification of the powertrain is seen as one of the key technologies to achieve these future goals. However, electrification of the power train typically goes with a massive cost increase of the overall system itself which is especially crucial for cost sensitive markets like India. AVL's approach to cost reduction for comparable performance and fuel consumption target values is an integration of functions. This paper demonstrates that, through a deeper interaction of the single powertrain components, further fuel efficiency optimization may be gained. System optimization at a powertrain level enables the achievement of future powertrain targets with respect to fuel efficiency and performance with only minimal and reduced requirements at a component level (i.e. combustion engine, electric drive, transmission and battery).
Journal Article

Compact Engine Architecture for Best Fuel Efficiency and High Performance - Challenge or Contradiction

The world of automotive engineering shows a clear direction for upcoming development trends. Stringent fleet average fuel consumption targets and CO2 penalties as well as rising fuel prices and the consumer demand to lower operating costs increases the engineering efforts to optimize fuel economy. Passenger car engines have the benefit of higher degree of technology which can be utilized to reach the challenging targets. Variable valve timing, downsizing and turbo charging, direct gasoline injection, highly sophisticated operating strategies and even more electrification are already common technologies in the automotive industry but can not be directly carried over into a motorcycle application. The major differences like very small packaging space, higher rated speeds, higher power density in combination with lower production numbers and product costs do not allow implementation such high of degree of advanced technology into small-engine applications.
Technical Paper

Consistent Development Methodology for hybrid AWD powertrains

Highest grow or highest attention in vehicles power-train is related to AWD and hybrid concepts. Some of the targets for these technologies are conflicting, others are very similar, and sometimes it depends on the application. In a first look it is very questionable weather these technologies should be combined. But it can be shown, that the combination makes quite some sense. It is possible to get the superior performance and enhance safety combined with reasonable fuel economy by hybridizing an AWD powertrain. From simulation to testing, efficient processes and a consistent development platform is key to fulfill all the development tasks in the environment of this increased complexity. Simulation and benchmark activities are valuable in the early project phases to define the targets and create the specifications. In the virtual world the system selection is a major task. To get appropriate results software modules are incorporated in the simulation environment.
Journal Article

High Performance Cooling and EGR Systems as a Contribution to Meeting Future Emission Standards

In relation to further tightening of the emissions legislation for on-road heavy duty Diesel engines, the future potential of cooled exhaust gas recirculation (EGR) as a result of developments in the cooling systems of such engines has been evaluated. Four basic engine concepts were investigated: an engine with SCR exhaust gas aftertreatment for control of the nitrogen oxides (NOx), an engine with cooled EGR and particulate (PM) filtration, an engine with low pressure EGR and PM filtration and an engine with two stage low temperature cooled EGR also with a particulate filter. A 10.5 litre engine was calibrated and tested under conditions representative for each concept, such that 1.7 g/kWh (1.3 g/bhp-hr) NOx could be achieved over the ESC and ETC. This corresponds to emissions 15% below the Euro 5 legislation level.
Technical Paper

The Challenge of Precise Characterizing the Specific Large-Span Flows in Urea Dosing Systems for NOx Reduction

The reduction of nitrous oxides in the exhaust gases of internal combustion engines using a urea water solution is gaining more and more importance. While maintaining the future exhaust gas emission regulations, like the Euro 6 for passenger cars and the Euro 5 for commercial vehicles, urea dosing allows the engine management to be modified to improve fuel economy as well. The system manufacturer Robert Bosch has started early to develop the necessary dosing systems for the urea water solution. More than 300.000 Units have been delivered in 2007 for heavy duty applications. Typical dosing quantities for those systems are in the range of 0.01 l/h for passenger car systems and up to 10 l/h for commercial vehicles. During the first years of development and application of urea dosing systems, instantaneous flow measuring devices were used, which were not operating fully satisfactory.
Technical Paper

Gasoline DI Engines: The Complete System Approach By Interaction of Advanced Development Tools

Gasoline direct injection is one of the main issues of actual worldwide SI engine development activities. It requires a comprehensive system approach from the basic considerations on optimum combustion system configuration up to vehicle performance and driveability. The general characteristics of currently favored combustion system configurations are discussed in this paper regarding both engine operation and design aspects. The engine performance, especially power output and emission potential of AVL's DGI engine concept is presented including the interaction of advanced tools like optical diagnostics and 3D-CFD simulation in the combustion system development process. The application of methods like tomographic combustion analysis for investigations in the multicylinder engine within further stages of development is demonstrated. The system layout and operational strategies for fuel economy in conjunction with exhaust gas aftertreatment requirements are discussed.
Technical Paper

Gasoline Direct Injection: Actual Trends and Future Strategies for Injection and Combustion Systems

Recent developments have raised increased interest on the concept of gasoline direct injection as the most promising future strategy for fuel economy improvement of SI engines. The general requirements for mixture preparation and combustion systems in a GDI engine are presented in view of known and actual systems regarding fuel economy and emission potential. The characteristics of the actually favored injection systems are discussed and guidelines for the development of appropriate combustion systems are derived. The differences between such mixture preparation strategies as air distributed fuel and fuel wall impingement are discussed, leading to the alternative approach to the problem of mixture preparation with the fully air distributing concept of direct mixture injection.
Technical Paper

CSI - Controlled Auto Ignition - the Best Solution for the Fuel Consumption - Versus Emission Trade-Off?

In recent years several new gasoline engine technologies were introduced in order to reduce fuel consumption. Controlled autoignition seems to be an alternative to stratified part load operation, which is handicapped due to it's lean aftertreatment system for world wide application. The principal advantages of controlled auto ignition combustion under steady state operation - combining fuel economy benefits similar to stratified charge systems with nearly negligible NOx and soot emissions - are already well known. With the newly developed AVL- CSI system (Compression and Spark Ignition), a precise combustion control is achieved even under transient operation. For compensation of production and operation tolerances a cost optimized cylinder individual control was developed. Completely new functionalities of the engine management system are applied. This lean GDI concept complies with future emission standards without DeNOx catalyst and can be applied worldwide.
Technical Paper

Intelligent Simplification-Ways Towards Improved Fuel Economy

A broad variety of new technologies for improving fuel economy is currently under development or investigation. The general statement is that always a compromise between fuel economy benefit and engine oncost has to be found. This paper describes a new way for improving fuel economy based on existing technologies used in a refined way. It is shown that with very simple and robust measures on the intake and exhaust ports and on the valve train mechanism 2 valve and 4 valve engines can show a significant improvement in fuel consumption without having a great cost penalty for production. The basic system consists of a single cam phaser and a special port arrangement on a 2 valve engine with a single camshaft operated at stoichiometric air/fuel ratio utilizing internal EGR and a reverse “Miller-Cycle”. Variable charge motion is generated using a shared flow through the intake and the exhaust port by varying cam timing.
Technical Paper

The Clean Heavy Duty Diesel Engine of the Future: Strategies for Emission Compliance

The internal combustion engines, and the heavy duty truck diesel engines in particular, are facing a severe challenge to cope with the upcoming stringent emission legislation world-wide. To comply with these low limits, engine internal measures must be complemented with exhaust gas aftertreatment systems with sophisticated electronic control. A reduction of NOx and particulate emission of more than 90% is required. Various strategies to comply with Euro 4, 5 and US 2007 are discussed, also in view of engine performance, fuel economy and cooling system load. Recommendations are given for the most suitable approach to comply also in future with emission legislation in Europe and the United States.
Technical Paper

Integrated Toolchain for Powertrain Optimization for Indian Commercial Vehicles

Best fuel efficiency is one of the core requirements for commercial vehicles in India. Consequently it is a central challenge for commercial vehicle OEMs to optimize the entire powertrain, hence match engine, transmission and rear axle specifications best to the defined application. The very specific real world driving conditions in India (e.g. traffic situations, road conditions, driver behavior, etc.) and the large number of possible commercial powertrain combinations request an efficient and effective development methodology. This paper presents a methodology and tool chain to specify and develop commercial powertrains in a most efficient and effective way. The methodology is based on the measurement of real world driving scenarios, identification of representative Real World Driving Profiles and vehicle system simulation which allows extended analysis of the road topography, the traffic situation as well as the driver behavior.
Technical Paper

ULEV and Fuel Economy - A Contradiction?

The CBR (Controlled Burn Rate) technology for MPFI engines is known to enable the reduction of throttle losses of gasoline engines by high EGR (Exhaust Gas Recirculation) rates due to the dilution tolerance of the swirl charge motion system using port deactivation. Now a new aspect of CBR is being developed: extremely low emissions during and after cold start. This paper is focused on the combustion stability and low emission aspects of CBR technology. It is shown how engine out emissions and catalyst light off behavior of an engine can be significantly improved using port deactivation. The very stable combustion directly after engine start, extremely retarded ignition timings in combination with lean engine operation and open valve injection with minimized wall wetting lead to very low HC emissions and very high exhaust gas temperatures.
Technical Paper

Turbocharging the DI Gasoline Engine

Regarding concepts for naturally aspirated engines, the high potential for fuel economy of Gasoline Direct Injection can only partially be utilized within the constraints of current or future emission legislation like EURO III / IV or LEV/ULEV. Instead of an expected improvement of 20 - 25 % currently only 10 - 15% can be obtained by the engine alone without vehicle optimizations considering all limitations of high volume production. A detailed analysis reveals concrete measures for further improvement. The application of DI gasoline technology clearly favors the combination with other fuel efficient technologies like downsizing by turbocharging and the application of a variable effective compression ratio by intake valve timing variation. Using the flexibility of direct gasoline injection some deficiencies of these technologies can be eliminated.
Technical Paper

Vehicle Driveability Assessment using Neural Networks for Development, Calibration and Quality Tests

Actual automotive themes in the beginning century are globalization and platform concepts. Platforms reduce manpower for basic power train development and enable a higher vehicle quality by sharing development cost to many models. New drive train generations with direct injected diesel and gasoline engines, variable valve train systems and hybrid drives require complex electronic control systems with many control parameters, which must be calibrated for each platform model to fulfill the targets for emissions, diagnostics and driveability. Calibration becomes a critical procedure in vehicle development. A negative effect of the platform is the reduced possibility to give a model or an OEM a brand specific driveability character, traditionally an important sales - promoting factor. The paper describes a tool for the objective real time assessment of vehicle driveability and vehicle character, using a new subjective - objective approach.
Technical Paper

Improvement of LEV/ULEV Potential of Fuel Efficient High Performance Engines

The combined requirement of achieving CAFE values between 32 to 38 mpg plus LEV/ULEV emission standards to comply with US legal requirements between 1995 and 2000 represents the most demanding challenge for engine engineering. Thus all possible methods of engine improvement towards fuel economy and emissions have to be considered. Besides using new ideas also the methods of engine development have to be modernized to cope with the challenge. The paper presents advanced combustion and exhaust gas aftertreatment systems which combine high power output, favourable torque characteristics and high fuel economy with the potential for obtaining LEV/ULEV emission values, as well as improved development techniques.
Technical Paper

Engineering Vehicle Sound Quality

The characteristically good fuel economy of the high speed direct injection diesel engine has led to increased market share as the power unit of passenger cars. This trend is particularly true in Europe and, if not halted prematurely by emissions legislation, is likely to continue. However, another characteristic of the high speed DI engine is increased noise and vibration over its gasoline counterpart. This has meant that additional noise and vibration measures are required in order to approach the competitive refinement levels of gasoline engine installations. This paper considers some of the characteristic diesel engine noise and vibration problems associated with vehicle installation and passenger comfort. The paper also discusses subjective and objective assessment and considers approaches to engineering more desirable sound quality.