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Technical Paper

Downsizing of Diesel Engines: 3-Cylinder / 4-Cylinder

2000-03-06
2000-01-0990
Due to the future application of combustion engines in small and hybrid vehicles, the demand for high efficiency with low mass and compact engine design is of prime importance. The diesel engine, with its outstanding thermal efficiency, is a well suited candidate for such applications. In order to realize these targets, future diesel engines will need to have increasingly higher specific output combined with increased power to weight ratios. This is therefore driving the need for new designs of 3 and/or 4 cylinder, small bore engines of low displacement, sub 1.5l. Recent work on combustion development, has shown that combustion systems, ports, valves and injector sizes are available for bore sizes down to 65 mm.
Technical Paper

Analysis of the Particle Size Distribution in the Cylinder of a Common Rail DI Diesel Engine During Combustion and Expansion

2000-06-19
2000-01-1999
In the recent years diesel engine developers and manufacturers achieved a great progress in reducing the most important diesel engine pollutants, NOX and particulates. But nevertheless big efforts in diesel engine development are necessary to meet with the more stringent future emission regulations. To improve the knowledge about particle formation and emission an insight in the cylinder is necessary. By using the fast gas sampling technique samples from the cylinder were taken as a function of crank angle and analyzed regarding the soot particle size distribution and the particle mass. The particle size distribution was measured by a conventional SMPS. Under steady state conditions the influence of aromatic and oxygen content in the fuel on in-cylinder particle size distribution and particle mass inside a modern 4V-CR-DI-diesel-engine were determined. After injection and ignition, mainly small soot particles were formed which grow and in the later combustion phase coagulate.
Technical Paper

Fuel Efficient Natural Gas Engine with Common-Rail Micro-Pilot Injection

2000-08-21
2000-01-3080
In the recent years, it has become obvious that one of the main fields of interest in alternate fuels is the public transportation sector. Natural Gas seems to be advantageous. It is available and environmentally friendly, even if the greenhouse effect of methane is considered. The operation range of vehicles running on CNG (Compressed Natural Gas) is poor due to the large pressure vessels, but in case of urban buses with low daily mileage this is acceptable. On the other hand, the use of an environmentally friendly fuel is favorable especially in urban areas. Although there are some advantages of Natural Gas, diesel buses dominate the market. The reason is the better part-load fuel efficiency of the Diesel principle which is superior to the Otto-cycle due to the absence of engine throttling. The efficiency levels of Spark-Ignition (SI) -type, Lean Burn Natural Gas engines are quite comparable to diesel engines during full load conditions.
Technical Paper

Vehicle Study on the Impact of Diesel Fuel Sulfur Content on the Performance of DeNOX Catalysts and the Influence of DeNOX Catalysts on Particle Size and Number

2000-06-19
2000-01-1877
A vehicle investigation programme was initiated to evaluate the influence of diesel fuel sulfur content on the performance of a DeNOx catalyst for NOx control. The programme was conducted with a passive DeNOx catalyst, selected for its good NOx reduction performance and two specially prepared fuels with different sulfur contents. Regulated emissions were measured and analysed during the course of the programme. The NOx conversion efficiency of the DeNOx catalyst increased from 14 to 26% over the new European test cycle when the sulfur content of the diesel fuel was reduced from 49 to 6 wt.-ppm. In addition the number and size of particles produced using 6 wt.-ppm sulfur fuel were measured by two different techniques: mobility diameter by SMPS and aerodynamic diameter by impactor. The influence of the assumed density of the particulate on the apparent diameters measured by the two techniques is discussed.
Technical Paper

Development of a Charge Motion Controlled Combustion System for DI SI-Engines and its Vehicle Application for EU-4 Emission Regulations

2000-03-06
2000-01-0257
The development of new passenger car powertrains with gasoline direct injection engines is facing new requirements which result from the need of different operational modes with stratified and homogeneous air fuel mixture. Moreover, the exhaust aftertreatment system causes a discontinuous operation with lean burn adsorption periods followed by short rich spikes for catalyst regeneration. Recent work on combustion system development has shown, that gasoline direct injection can create significant fuel economy benefits. Charge motion controlled combustion systems have proven to be of advantage in terms of low raw emissions compared to wall guided concepts. Based on an initial single-cylinder development phase a multi-cylinder engine was realized with excellent fuel economy, low raw emissions and operational robustness. Finally, the new engine's potential has been demonstrated in a mid-class vehicle.
Technical Paper

Mechanical Testing - Still Necessary!

2007-04-16
2007-01-1768
Over the last decades, the use of computers has become an integral part of the engine development process. Computer-based tools are increasingly used in the design process, and especially the layout of the various subsystems is conducted by means of simulation models. Computer-aided engineering plays a central role e.g. in the design of the combustion process as well as with regards to work performed in the area of engine mechanics, where CFD, FEM, and MBS are applied. As a parallel trend, it can be observed that various engine performance characteristics such as e.g. the specific power output and the power-to-weight ratio have undergone an enormous increase, a trend which to some extent counteracts the increase in safety against malfunction and failure. As yet, due to the constant need for further optimization, mechanical testing and verification processes have not become redundant, and it is assumed that they will remain indispensable for the foreseeable future.
Technical Paper

Active Noise Cancellation at Powertrain Oil Pan

2007-05-15
2007-01-2422
Under city driving conditions, the powertrain represents one of the major vehicle exterior noise sources. Especially at idle and during full load acceleration, the oil pan contributes significantly to the overall powertrain sound emission. The engine oilpan can be a significant contributor to the powertrain radiated sound levels. Passive optimization measures, such as structural optimization and acoustic shielding, can be limited by e.g. light-weight design, package and thermal constraints. Therefore, the potential of the Active Structure Acoustic Control (ASAC) method for noise reduction was investigated within the EU-sponsored project InMAR. The method has proven to have significant noise reduction potential with respect to oil pan vibration induced noise. The paper reports on activities within the InMAR project with regard to a passenger car oil pan application of an ASAC system based on piezo-ceramic foil technology.
Technical Paper

Accelerated Powertrain Development Through Model Based Calibration

2006-04-03
2006-01-0858
Modern powertrain development is targeting to meet challenging, to some degrees contradictory development goals in a short timeframe. Looking to a development time schedule of 36 months from concept to SOP, it becomes a prerequisite that unnecessary design loops have to be avoided by all means. Now, in addition, the experimental development work has to be conducted more efficiently than in the past. In recent years methods for an efficient design process have been successfully applied. Testing and vehicle application work can take advantage of methods empowered by model based approaches. Today, models with different levels of detail are able to significantly improve nearly every development phase. Supported by standardized and automated test bench and vehicle procedures an efficient and comprehensive development process can be established and utilized, which is also necessary to tackle growing complexity.
Technical Paper

Potential of Synthetic Fuels in Future Combustion Systems for HSDI Diesel Engines

2006-04-03
2006-01-0232
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.
Technical Paper

Opposed Piston Opposed Cylinder (opoc™) 450 hp Engine: Performance Development by CAE Simulations and Testing

2006-04-03
2006-01-0277
The new opoc™ diesel engine concept was presented at the SAE 2005 World Congress [1]. Exceptional power density of >1hp/lb and >40% efficiency have been predicted for the 2-stroke opoc™ diesel engine concept. Intensive CAE simulations have been performed during the concept and design phase in order to define the baseline scavenging and combustion parameters, such as port timing, turbocharger configuration and fuel injection nozzle design. Under a DARPA contract, first prototype engines have been built and have undergone a validation testing program. The main goal of the first testing phase was to demonstrate the power output capability of the new engine concept. In close relationship and interaction of testing and CAE simulation, the uniflow scavenging process and parameters of the special diesel direct side injection have been optimized. This paper discusses the latest results of the opoc engine development.
Technical Paper

Modern Gear Train Simulation Process for the Virtual Engine and Transmission Development

2006-04-03
2006-01-0585
Current simulation tools for the investigation of the dynamic system response as well as for the component stresses on the basis of multi-body and finite-element techniques are integral part of today's powertrain development efforts. These tools are typical used for the analysis and optimization of shafts, clutches, chain/belt drives, bearings, levers, brackets, housings and many other components. An exception is made by gears which today are still frequently investigated by the help of semi-empirical methods based on DIN, ISO, AGMA and the specific knowledge base of well experienced developers. The main difficulty is that the gears are rolling off via large contact surfaces with complex nonlinear mechanical contact properties. Within the scope of research work FEV developed a new method for the analysis and optimization of gear drives based on comercial multi-body and finite-element software platforms.
Technical Paper

HiL-based ECU-Calibration of SI Engine with Advanced Camshaft Variability

2006-04-03
2006-01-0613
A main focus of development in modern SI engine technology is variable valve timing, which implies a high potential of improvement regarding fuel consumption and emissions. Variable opening, period and lift of inlet and outlet valves enable numerous possibilities to alter gas exchange and combustion. However, this additional variability generates special demands on the calibration process of specific engine control devices, particularly under cold start and warm-up conditions. This paper presents procedures, based on Hardware-in-the-Loop (HiL) simulation, to support the classical calibration task efficiently. An existing approach is extended, such that a virtual combustion engine is available including additional valve timing variability. Engine models based purely on physical first principles are often not capable of real time execution. However, the definition of initial parameters for the ECU requires a model with both real time capability and sufficient accuracy.
Technical Paper

Applying Representative Interactive Flamelets (RIF) with Special Emphasis on Pollutant Formation to Simulate a DI Diesel Engine with Roof-Shaped Combustion Chamber and Tumble Charge Motion

2007-04-16
2007-01-0167
Combustion and pollutant formation in a new recently introduced Common-Rail DI Diesel engine concept with roof-shaped combustion chamber and tumble charge motion are numerically investigated using the Representative Interactive Flamelet concept (RIF). A reference case with a cup shaped piston bowl for full load operating conditions is considered in detail. In addition to the reference case, three more cases are investigated with a variation of start of injection (SOI). A surrogate fuel consisting of n-decane (70% liquid volume fraction) and α-methylnaphthalene (30% liquid volume fraction) is used in the simulation. The underlying complete reaction mechanism comprises 506 elementary reactions and 118 chemical species. Special emphasis is put on pollutant formation, in particular on the formation of NOx, where a new technique based on a three-dimensional transport equation within the flamelet framework is applied.
Technical Paper

Combined Particulate Matter and NOx Aftertreatment Systems for Stringent Emission Standards

2007-04-16
2007-01-1128
The HSDI Diesel engine contributes substantially to the decrease of fleet fuel consumption thus to the reduction of CO2 emissions. This results in the rising market acceptance which is supported by desirable driving performance as well as greatly improved NVH behavior. In addition to the above mentioned requirements on driving performance, fuel economy and NVH behavior, continuously increasing demands on emissions performance have to be met. From today's view the Diesel particulate trap presents a safe technology to achieve the required reduction of the particle emission of more than 95%. However, according to today's knowledge a further, substantial NOx engine-out emission reduction for the Diesel engine is counteracts with the other goal of reduced fuel consumption. To comply with current and future emission standards, Diesel engines will require DeNOx technologies.
Technical Paper

Potential of the Spray-guided Combustion System in Combination with Turbocharging

2008-04-14
2008-01-0139
Based on the TurboDISI engine presented earlier [1], [2], a new Spray Guided Turbo (SGT) concept with enhanced engine performance was developed. The turbocharged engine was modified towards utilizing a spray-guided combustion system with a central piezo injector location. Higher specific power and torque levels were achieved by applying specific design and cooling solutions. The engine was developed utilizing a state-of-the-art newly developed charge motion design (CMD) process in combination with single cylinder investigations. The engine control unit has a modular basis and is realized using rapid prototyping hardware. Additional fuel consumption potentials can be achieved with high load EGR, use of alternative fuels and a hybrid powertrain. The CO2 targets of the EU (120 g/km by 2012 in the NEDC) can be obtained with a mid-size vehicle applying the technologies presented within this paper.
Technical Paper

Low fuel consumption and low emissions~Electromechanical valve train in vehicle operation

2000-06-12
2000-05-0018
The electromechanical valve train (EMV) technology allows for a reduction in fuel consumption while operating under a stoichiometric air-fuel ratio and preserves the ability to use conventional exhaust gas aftertreatment technology with a 3-way catalyst. Compared with an engine with a camshaft-driven valve train, the variable valve timing concept makes possible an additional optimization of cold start, warm-up and transient operation. In contrast with the conventionally throttled engine, optimized control of load and in-cylinder gas movement can be used for each individual cylinder and engine cycle. A load control strategy using a "Late Intake Valve Open" (LIO) provides a reduction in start-up HC emissions of approximately 60%. Due to reduced wall-wetting, the LIO control strategy improves the transition from start to idle.
Technical Paper

New CNG Concepts for Passenger Cars: High Torque Engines with Superior Fuel Consumption

2003-06-23
2003-01-2264
Since the CO2 emissions of passenger car traffic and their greenhouse potential are in the public interest, natural gas (CNG) is discussed as an attractive alternative fuel. The engine concepts that have been applied to date are mainly based upon common gasoline engine technology. In addition, in mono-fuel applications, it is made use of an increased compression ratio -thanks to the RON (Research Octane Number) potential of CNG-, which allows for thermodynamic benefits. This paper presents advanced engine concepts that make further use of the potentials linked to CNG. Above all, the improved knock tolerance, which can be particularly utilized in turbocharged engine concepts. For bi-fuel (CNG/gasoline) power trains, the realization of variable compression ratio is of special interest. Moreover, lean burn technology is a perfect match for CNG engines. Fuel economy and emission level are evaluated basing on test bench and vehicle investigations.
Technical Paper

Sound Quality and Engine Performance Development Utilizing Air-to-Air Simulation and Interior Noise Synthesis

2003-05-05
2003-01-1652
The sound quality and performance of an automotive engine are both significantly influenced by the “air-to-air” system, i.e., the intake system, the exhaust system, and the engine gas dynamics. Only a full systems approach can result in an optimized air-to-air system, which fulfills engine performance requirements, overall sound pressure level targets for airborne vehicle noise, as well as sound quality demands. This paper describes an approach, which considers the intake system, engine, and exhaust system within one CAE model that can be utilized for engine performance calculations as well as acoustic simulations. Examples comparing simulated and measured sound are discussed. Finally, the simulated sound (e.g., at the tailpipe of the exhaust system) is combined with an interior noise simulation technique to evaluate its influence inside the vehicle's interior.
Technical Paper

The Diesel Exhaust Aftertreatment (DEXA) Cluster: A Systematic Approach to Diesel Particulate Emission Control in Europe

2004-03-08
2004-01-0694
The DEXA Cluster consisted of three closely interlinked projects. In 2003 the DEXA Cluster concluded by demonstrating the successful development of critical technologies for Diesel exhaust particulate after-treatment, without adverse effects on NOx emissions and maintaining the fuel economy advantages of the Diesel engine well beyond the EURO IV (2000) emission standards horizon. In the present paper the most important results of the DEXA Cluster projects in the demonstration of advanced particulate control technologies, the development of a simulation toolkit for the design of diesel exhaust after-treatment systems and the development of novel particulate characterization methodologies, are presented. The motivation for the DEXA Cluster research was to increase the market competitiveness of diesel engine powertrains for passenger cars worldwide, and to accelerate the adoption of particulate control technology.
Technical Paper

LOTUS: A Co-operation for Low Temperature Urea-Based Selective Catalytic Reduction of NOx

2004-03-08
2004-01-1294
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.
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