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Technical Paper

Optimum Diesel Fuel for Future Clean Diesel Engines

2007-01-23
2007-01-0035
Over the next decades to come, fossil fuel powered Internal Combustion Engines (ICE) will still constitute the major powertrains for land transport. Therefore, their impact on the global and local pollution and on the use of natural resources should be minimized. To this end, an extensive fundamental and practical study was performed to evaluate the potential benefits of simultaneously co-optimizing the system fuel-and-engine using diesel as an example. It will be clearly shown that the still unused co-optimizing of the system fuel-and-engine (including advanced exhaust after-treatment) as a single entity is a must for enabling cleaner future road transport by cleaner fuels since there are large, still unexploited potentials for improvements in road fuels which will provide major reductions in pollutant emissions both in vehicles already in the field and even more so in future dedicated vehicles.
Technical Paper

Optical investigation of injection and combustion in a small direct injection diesel engine

2001-09-23
2001-24-0018
A new phenomenological model of injection and auto-ignition is established in a 4-cylinder DI diesel engine of the production size class equipped with an inclined 5 holes injector. Measurements are performed at representative engine conditions for partial load. The penetration of the liquid phases is visualized in the whole combustion chamber by simultaneous Laser-Induced Fluorescence (LIF) and Mie scattering techniques. The autoignition and combustion are analyzed by a time-resolved direct imaging of the chemiluminescence process. Experiments based on the correlation of two separated images of the combustion phenomena in a single cycle have allowed a detailed comprehension of spatial and temporal description of the autoignition and reaction zones development. Several autoignition sites are revealed in the vicinity of the injector nozzle. The reaction zone is shown to develop independently and then to merge to a unique one in the whole combustion chamber.
Technical Paper

Exhaust Gas Aftertreatment of Volkswagen FSI Fuel Stratified Injection Engines

2002-03-04
2002-01-0346
For substantial reduction of fuel consumption of their vehicle fleet, Volkswagen AG has decided to develop spark-ignition engines with direct fuel injection. To launch this new engine concept with stratified lean operation mode while at the same time meeting the stringent EU IV emission standards, it was necessary to develop a suitable exhaust gas aftertreatment system. This was achieved as part of an intensive co-operation between Volkswagen AG and OMG, formerly dmc2 Degussa Metals Catalysts Cerdec AG. The paper describes the demands for exhaust gas aftertreatment due to lean burn operation. In addition the main development steps of the exhaust gas aftertreatment system for Volkswagen FSI engines and catalyst durability over vehicle lifetime are discussed. Focus is laid on the catalyst system design and coating variations. Volkswagen developed a new closed-loop emission control management system which uses NOx-sensor signals for the first time worldwide.
Technical Paper

Research Results and Progress in LeaNOx II -A Co-operation for Lean NOx Abatement

2000-10-16
2000-01-2909
In a consortium of European industrial partners and research institutes, a combination of industrial development and scientific research was organised. The objective was to improve the catalytic NOx conversion for lean burn cars and heavy-duty trucks, taking into account boundary conditions for the fuel consumption. The project lasted for three years. During this period parallel research was conducted in research areas ranging from basic research based on a theoretical approach to full scale emission system development. NOx storage catalysts became a central part of the project. Catalysts were evaluated with respect to resistance towards sulphur poisoning. It was concluded that very low sulphur fuel is a necessity for efficient use of NOx trap technology. Additionally, attempts were made to develop methods for reactivating poisoned catalysts. Methods for short distance mixing were developed for the addition of reducing agent.
Technical Paper

Vw Lupo, the WorldS First 3-Liter Car

2000-11-01
2000-01-C044
After the success of the 4-cylinder 1.9-liter TDI and SDI direct-injection diesel engines in the Passat, Jetta and Polo classes, a new 3-cylinder TDI has been developed for use in the "Lupo 3L,' a compact car with a fuel consumption of 3 liters per 100 km. A new injection system with unit injectors, together with a fully electronically controlled engine management system featuring drive-by-wire- technology, a turbocharger with variable turbine geometry and a fully automated mechanical gearbox and clutch, for the first time ensures the potential to meet the stringent D4 exhaust emissions level and to achieve excellent fuel economy. The wheel-torque based engine and gearbox management systems optimize engine operation in terms of efficiency and emissions.
Technical Paper

In-Cylinder Velocity Measurements with Stereoscopic Particle Image Velocimetry in a SI engine

2000-06-19
2000-01-1798
Particle Image Velocimetry (PIV) technique was used to study the in-cylinder flow motion in a single cylinder transparent spark ignition (SI) engine, with 4 valves pent-roof cylinder-head. Experiments have been firstly performed using classical PIV technique in the symmetrical plane of the combustion chamber. The instantaneous two-dimensional velocity fields show that during intake stroke, the flow has strong relatively stable structures with low cycle by cycle (CBC) variations, whereas during compression stroke, the flow consists of large unstable eddies with high CBC variations. In all cases, no large tumble-like motion was observed on instantaneous fields in the measurement plane during the intake stroke. Therefore, Stereoscopic Particle Image Velocimetry (SPIV) technique was adapted to complete the classical two-dimensional measurements and in order to have a better understanding of the in-cylinder flow during compression stroke.
Technical Paper

Engine-Independent Exhaust Gas Aftertreatment Using a Burner Heated Catalyst

2006-10-16
2006-01-3401
Meeting current exhaust emission standards requires rapid catalyst light-off. Closed-coupled catalysts are commonly used to reduce light-off time by minimizing exhaust heat loss between the engine and catalyst. However, this exhaust gas system design leads to a coupling of catalyst heating and engine operation. An engine-independent exhaust gas aftertreatment can be realized by combining a burner heated catalyst system (BHC) with an underfloor catalyst located far away from the engine. This paper describes some basic characteristics of such a BHC system and the results of fitting this system into a Volkswagen Touareg where a single catalyst was located about 1.8 m downstream of the engine. Nevertheless, it was possible to reach about 50% of the current European emission standard EU 4 without additional fuel consumption caused by the BHC system.
Technical Paper

Locally Resolved Measurement of Gas-Phase Temperature and EGR-Ratio in an HCCI-Engine and Their Influence on Combustion Timing

2007-04-16
2007-01-0182
Laser-based measurements of charge temperature and exhaust gas recirculation (EGR) ratio in an homogeneous charge compression ignition (HCCI) engine are demonstrated. For this purpose, the rotational coherent anti-Stokes Raman spectroscopy technique (CARS) was used. This technique allows temporally and locally resolved measurements in combustion environments through only two small line-of-sight optical accesses and the use of standard gasoline as a fuel. The investigated engine is a production-line four-cylinder direct-injection gasoline engine with the valve strategy modified to realize HCCI-operation. CARS-measurements were performed in motored and fired operation and the results are compared to polytropic calculations. Studies of engine speed, load, valve timing, and injection pressure were conducted showing the strong influence of charge temperature on the combustion timing.
Technical Paper

Application of Vehicle Interior Noise Simulation (VINS) for NVH Analysis of a Passenger Car

2005-05-16
2005-01-2514
The overall perception of a vehicle's quality is significantly influenced by its interior noise characteristics. Therefore, it is important to strike a balance between “pleasant” and “dynamic” sound that fits the customer requirements with respect to vehicle brand and class [1]. Typically, a significant share of the interior vehicle noise is transferred through structure-borne paths. Hence, the powertrain mounting system plays an important role in designing the interior noise. This paper describes an application of the method of vehicle interior noise simulation (VINS) to achieve a characteristic interior sound. This approach is based on separate measurements (or calculations) of excitations and transfer functions and subsequent calculation of the interior noise in the time domain.
Technical Paper

Effect of HPDC Parameters on the Performance of Creep Resistant Alloys MRI153M and MRI230D

2005-04-11
2005-01-0334
The growing demand for the use of magnesium alloys in the production of automotive powertrain components led to the development of creep resistant diecasting alloys MRI153M and MRI230D. The present paper addresses the main high-pressure die casting parameters, which significantly affect the performance of components, produced of these new alloys. A systematic study was carried out in order to correlate die-casting parameters to the performance of new alloys. The results obtained clearly indicated that optimization of molten metal and die temperatures, injection profile parameters and lubrication mixtures allowed to improve the die castability and service properties of the new alloys and produce high performance components with intricate geometry. This was manifested by production of several practical demonstrators such as gearboxes, oil pans, oil pumps and crankcases.
Technical Paper

NO Laser-Induced Fluorescence Imaging in the Combustion Chamber of a Spray-Guided Direct-Injection Gasoline Engine

2004-06-08
2004-01-1918
In direct-injection gasoline (GDI) engines with charge stratification, minimizing engine-out nitrogen oxide (NOx) emission is crucial since exhaust-gas aftertreatment tolerates only limited amounts of NOx. Reduced NOx production directly lowers the frequency of energy-inefficient catalyst regeneration cycles. In this paper we investigate NO formation in a realistic GDI engine. Quantitative in-cylinder measurements of NO concentrations are carried out via laser-induced fluorescence imaging with excitation of NO (A-X(0,2) band at 248 nm), and subsequent fluorescence detection at 220-240 nm. Engine modifications were kept to a minimum in order to provide results that are representative of practical operating conditions. Optical access via a sapphire ring enabled identical engine geometry as a production line engine. The engine is operated with commercial gasoline (“Super-Plus”, RON 98).
Technical Paper

A PDF-Based Model for Full Cycle Simulation of Direct Injected Engines

2008-06-23
2008-01-1606
In one-dimensional engine simulation programs the simulation of engine performance is mostly done by parameter fitting in order to match simulations with experimental data. The extensive fitting procedure is especially needed for emissions formation - CO, HC, NO, soot - simulations. An alternative to this approach is, to calculate the emissions based on detailed kinetic models. This however demands that the in-cylinder combustion-flow interaction can be modeled accurately, and that the CPU time needed for the model is still acceptable. PDF based stochastic reactor models offer one possible solution. They usually introduce only one (time dependent) parameter - the mixing time - to model the influence of flow on the chemistry. They offer the prediction of the heat release, together with all emission formation, if the optimum mixing time is given.
Technical Paper

Benefits of GTL Fuel in Vehicles Equipped with Diesel Particulate Filters

2009-06-15
2009-01-1934
Synthetic fuels are expected to play an important role for future mobility, because they can be introduced seamlessly alongside conventional fuels without the need for new infrastructure. Thus, understanding the interaction of GTL fuels with modern engines, and aftertreatment systems, is important. The current study investigates potential benefits of GTL fuel in respect of diesel particulate filters (DPF). Experiments were conducted on a Euro 4 TDI engine, comparing the DPF response to two different fuels, normal diesel and GTL fuel. The investigation focused on the accumulation and regeneration behavior of the DPF. Results indicated that GTL fuel reduced particulate formation to such an extent that the regeneration cycle was significantly elongated, by ∼70% compared with conventional diesel. Thus, the engine could operate for this increased time before the DPF reached maximum load and regeneration was needed.
Technical Paper

The Response of a Closed Loop Controlled Diesel Engine on Fuel Variation

2008-10-06
2008-01-2471
An investigation was conducted to elucidate, how the latest turbocharged, direct injection Volkswagen diesel engine generation with cylinder pressure based closed loop control, to be launched in the US in 2008, reacts to fuel variability. A de-correlated fuels matrix was designed to bracket the range of US market fuel properties, which allowed a clear correlation of individual fuel properties with engine response. The test program consisting of steady state operating points showed that cylinder pressure based closed loop control successfully levels out the influence of fuel ignition quality, showing the effectiveness of this new technology for markets with a wide range of fuel qualities. However, it also showed that within the cetane range tested (39 to 55), despite the constant combustion mid-point, cetane number still has an influence on particulate and gaseous emissions. Volatility and energy density also influence the engine's behavior, but less strongly.
Technical Paper

Gasoline HCCI/CAI on a Four-Cylinder Test Bench and Vehicle Engine - Results and Conclusions for the Next Investigation Steps

2010-05-05
2010-01-1488
Internal combustion engines with lean homogeneous charge and auto-ignition combustion of gasoline fuels have the capability to significantly reduce fuel consumption and realize ultra-low engine-out NOx emissions. Group research of Volkswagen AG has therefore defined the Gasoline Compression Ignition combustion (GCI®) concept. A detailed investigation of this novel combustion process has been carried out on test bench engines and test vehicles by group research of Volkswagen AG and IAV GmbH Gifhorn. Experimental results confirm the theoretically expected potential for improved efficiency and emissions behavior. Volkswagen AG and IAV GmbH will utilize a highly flexible externally supercharged variable valve train (VVT) engine for future investigations to extend the understanding of gas exchange and EGR strategy as well as the boost demands of gasoline auto-ignition combustion processes.
Technical Paper

New ways of fluid flow control in automobiles: Experience with exhaust gas aftertreatmetn control

2000-06-12
2000-05-0299
Flow control by fluidic devices - without moving parts - offers advantages of reliability and low cost. As an example of their automobile application based on authors'' long-time experience the paper describes a fluidic valve for switching exhaust gas flow in a NOx absorber into a by-pass during regeneration phase. The unique feature here is the fluidic valve being of monostable and of axisymmetric design, integrated into the absorber body. After development in aerodynamic laboratory, the final design was tested on engine test stand and finally in a car. This proved that the performance under high temperature and pulsation existing in exhaust systems is reliable and promising. Fluidic valves require, however, close matching with aerodynamic load. To optimize the exhaust system layout for the whole load-speed range and reaching minimum counter- pressure, both the components of exhaust system and control strategy have to be properly adopted.
Technical Paper

The New Diesel Engine in the New Beetle

1998-08-11
981950
With the introduction of the New Beetle, Volkswagen is offering the next generation of the 1.9l TDI engine. Several evolutionary changes have been made to the TDI concept to further improve its emissions, efficiency and performance. Emissions performance is improved with increased fuel injection pressure, optimized fuel injectors, calibration modifications, EGR cooling and reduced crevice volume in the combustion chamber. Efficiency is improved with new oil pump, vacuum pump and water pump drive systems and the elimination of an auxiliary driveshaft. Performance and efficiency is improved with the addition of a variable geometry turbocharger, which increases torque at lower engine speeds while preserving performance at higher engine speeds. This paper describes the many enhancements found in this latest generation TDI and gives a brief lookout to the future trends in diesel engine development such as a high pressure injection system with unit injectors.
Technical Paper

Experimental and Numerical Analysis of Pre-Chamber Combustion Systems for Lean Burn Gas Engines

2019-04-02
2019-01-0260
The current trend in automobiles is towards electrical vehicles, but for the most part these vehicles still require an internal combustion engine to provide additional range and flexibility. These engines are under stringent emissions regulations, in particular, for the reduction of CO2. Gas engines which run lean burn combustion systems provide a viable route to these emission reductions, however designing these engines to provide sustainable and controlled combustion under lean conditions at λ=2.0 is challenging. To address this challenge, it is possible to use a scavenged Pre-Chamber Ignition (PCI) system which can deliver favorable conditions for ignition close to the spark plug. The lean charge in the main combustion chamber is then ignited by flame jets emanating from the pre-chamber nozzles. Accurate prediction of flame kernel development and propagation is essential for the analysis of PCI systems.
Technical Paper

Investigation of an Innovative Combustion Process for High-Performance Engines and Its Impact on Emissions

2019-01-15
2019-01-0039
Over the past years, the question as to what may be the powertrain of the future has become ever more apparent. Aiming to improve upon a given technology, the internal combustion engine still offers a number of development paths in order to maintain its position in public and private mobility. In this study, an innovative combustion process is investigated with the goal to further approximate the ideal Otto cycle. Thus far, similar approaches such as Homogeneous Charge Compression Ignition (HCCI) shared the same objective yet were unable to be operated under high load conditions. Highly increased control efforts and excessive mechanical stress on the components are but a few examples of the drawbacks associated with HCCI. The approach employed in this work is the so-called Spark Assisted Compression Ignition (SACI) in combination with a pre-chamber spark plug, enabling short combustion durations even at high dilution levels.
Technical Paper

Steering Feedback Perception of Average Drivers

2018-04-15
2018-01-5015
Electromechanical steering systems (EPS) provide assisting steering force through an electric motor, often paired with a screw drive. The combination of an electric motor and a screw drive lead to high inertia and thus to a reduced feedback of tire force behavior at the steering wheel. This force behavior contains information about driving conditions and road surface. However, the electric motor can be used to actively enhance and manipulate steering feedback. This article describes the driver perception of modified steering feedback. The presented data is collected carrying out a driving simulator study with average drivers as test subjects. In this study the driver experiences a modified steering feedback at a change of road friction coefficient. Based on the test subjects ratings the perception, acceptance and controllability of the presented steering feedback modifications are assessed.
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