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Journal Article

Possible Influences on Fuel Consumption Calculations while using the Hydrogen-Balance Method

2008-04-14
2008-01-1037
The Hydrogen-Balance equation makes it possible to calculate the fuel economy or fuel consumption of hydrogen powered vehicles simply by analyzing exhaust emissions. While the benefits of such a method are apparent, it is important to discuss possible influencing factors that may decrease Hydrogen-Balance accuracy. Measuring vehicle exhaust emissions is done with a CVS (Constant Volume Sampling) system. While the CVS system has proven itself both robust and precise over the years, utilizing it for hydrogen applications requires extra caution to retain measurement accuracy. Consideration should be given to all testing equipment, as well as the vehicle being tested. Certain environmental factors may also play a role not just in Hydrogen-Balance accuracy, but as also in other low emission testing accuracy.
Technical Paper

The Particle Number Counter as a “Black Box” - A Novel Approach to a Universal Particle Number Calibration Standard for Automotive Exhaust

2020-09-15
2020-01-2195
The reduction of vehicle exhaust particle emissions is a success story of European legislation. Various particle number (PN) counters and calibration procedures serve as tools to enforce PN emission limits during vehicle type approval (VTA) or periodical technical inspection (PTI) of in-use vehicles. Although all devices and procedures apply to the same PN-metric, they were developed for different purposes, by different stakeholder groups and for different target costs and technical scopes. Furthermore, their calibration procedures were independently defined by different stakeholder communities. This frequently leads to comparability and interpretation issues. Systematic differences of stationary and mobile PN counters (PN-PEMS) are well-documented. New, low-cost PTI PN counters will aggravate this problem. Today, tools to directly compare different instruments are scarce.
Technical Paper

New Driving Stability Control System with Reduced Technical Effort for Compact and Medium Class Passenger Cars

1998-02-23
980234
Wheel slip control system have found a remarkable penetration in all car segments. The information on the wheel behavior has lead to further developments which control the brake performance as well as the driving of the car in general. Latest systems introduced especially on luxury cars use wheel individual brake intervention to ensure vehicle stability under various driving maneuvers within the physical limits. Such systems use vehicle dynamic sensors and special hydraulics which serve as energy source for the automatic brake application. The technical effort of such systems like the Dynamic Stability Control DSC has limited the installation to upper class cars so far. New approaches are required to allow for a more wide spread penetration. Optimized hydraulics together with a rational design of the electronics seems to offer a basis for a more cost effective design.
Technical Paper

The Development of BMW Catalyst Concepts for LEV / ULEV and EU III / IV Legislations 6 Cylinder Engine with Close Coupled Main Catalyst

1998-02-23
980418
To meet LEV and EU Stage III emission requirements, it is necessary for new catalytic converters to be designed which exceed light-off temperature as quickly as possible. The technical solutions are secondary air injection, active heating systems such as the electrically heated catalytic converter, and the close coupled catalytic converter. Engine control functions are extensively used to heat the converter and will to play a significant role in the future. The concept of relocating the converter to a position close to the engine in an existing vehicle involves new conflicts. Examples include the space requirements, the thermal resistance of the catalytic coating and high temperature loads in the engine compartment.
Technical Paper

Equations and Methods for Testing Hydrogen Fuel Consumption using Exhaust Emissions

2008-04-14
2008-01-1036
Although hydrogen ICE engines have existed in one sort or another for many years, the testing of fuel consumption by way of exhaust emissions is not yet a proven method. The current consumption method for gasoline- and diesel-fueled vehicles is called the Carbon-Balance method, and it works by testing the vehicle exhaust for all carbon-containing components. Through conservation of mass, the carbon that comes out as exhaust must have gone in as fuel. Just like the Carbon-Balance method for gas and diesel engines, the new Hydrogen-Balance equation works on the principle that what goes into the engine must come out as exhaust components. This allows for fuel consumption measurements without direct contact with the fuel. This means increased accuracy and simplicity. This new method requires some modifications to the testing procedures and CVS (Constant Volume Sampling) system.
Technical Paper

A New Method for the Investigation of Unburned Oil Emissions in the Raw Exhaust of SI Engines

1998-10-19
982438
The study of oil emission is of essential interest for the engine development of modern cars, as well as for the understanding of hydrocarbon emissions especially during cold start conditions. A laser mass spectrometer has been used to measure single aromatic hydrocarbons in unconditioned exhaust gas of a H2-fueled engine at stationary and transient motor operation. These compounds represent unburned oil constituents. The measurements were accompanied by FID and GC-FID measurements of hydrocarbons which represent the burned oil constituents. The total oil consumption has been determined by measuring the oil sampled by freezing and weighing. It has been concluded that only 10 % of the oil consumption via exhaust gas has burned in the cylinders. A correlation of the emission of single oil-based components at ppb level detected with the laser mass spectrometer to the total motor oil emission has been found.
Technical Paper

2D Mapping and Quantification of the In-Cylinder Air/Fuel-Ratio in a GDI Engine by Means of LIF and Comparison to Simultaneous Results from 1D Raman Measurements

2001-05-07
2001-01-1977
The optimization of the vaporization and mixture formation process is of great importance for the development of modern gasoline direct injection (GDI) engines, because it influences the subsequent processes of the ignition, combustion and pollutant formation significantly. In consequence, the subject of this work was the development of a measurement technique based on the laser induced exciplex fluorescence (LIF), which allows the two dimensional visualization and quantification of the in-cylinder air/fuel ratio. A tracer concept consisting of benzene and triethylamine dissolved in a non-fluorescent base fuel has been used. The calibration of the equivalence ratio proportional LIF-signal was performed directly inside the engine, at a well known mixture composition, immediately before the direct injection measurements were started.
Technical Paper

Sizing in Conceptual Design at BMW

2004-03-08
2004-01-1657
In the early stages of conceptual design the available geometric data are very coarse and the lifespan of a design idea is very short. The structural evaluation and improvement of a design has to take both facts into account. Its focus is on the total vehicle and its performance. This can be estimated by a modeling technique, which is adequate for the lack of geometric details. Static and dynamic global stiffness as well as some aspects of crash and NVH have to be considered. Optimization will lead to the proper sizing and some indication of the potential of the structure. In order to maintain high quality standards this approach has to be supported by specialized CAE tools and extensive rules on modeling techniques and analysis procedures.
Technical Paper

Advanced Lighting Simulation (ALS) for the Evaluation of the BMW System Adaptive Light Control (ALC)

2002-07-09
2002-01-1988
The Advanced Lighting Simulation (ALS) is a development tool for systematically investigating and optimizing the Adaptive Light Control (ALC) system to provide the driver with improved headlamps and light distributions. ALS is based on advanced CA-techniques and modern validation facilities. To improve night time traffic safety the BMW lighting system ALC has been developed and optimized with the help of ALS. ALC improves the headlamp illumination by means of continuous adaptation of the headlamps according to the current driving situation and current environment. BMW has already implemented ALC prototypes in real vehicles to demonstrate the advantages on the real road.
Technical Paper

Problems of Partial Sample Systems for Modal Raw Exhaust Mass Emission Measurement

2003-03-03
2003-01-0779
Changing of emission levels leads to an increasing demand for a satisfying solution to measure mass emissions of motor vehicles on both, engine and chassis dynamometers. Partial flow systems may fit to the demands. These systems require an exact determination of exhaust volume flow and time aligned concentration measurement. This paper will address these issues and problems related with partial flow sampling. Several exhaust flow measurement systems have been studied and integrated mass results have been checked against the full flow CVS. As the investigations indicate, modal mass calculation from sampling direct exhaust at the end of tailpipe is feasible but not a satisfying solution in equivalency and repeatability in comparison to CVS-results. This is especially the case on emission levels near or below ULEV.
Technical Paper

HC Measurements by Means of Flame Ionization: Background and Limits of Low Emission Measurement

2003-03-03
2003-01-0387
Flame Ionization Detectors (FID) can be used to detect organic hydrocarbons that occur in plastics, lacquers, adhesives, solvents and gasoline. These substances are ionized in the hydrogen flame of the FID. The ionization current that is produced depends on the amount of hydrocarbon in the sample. With the lowering of emissions limits, measuring instruments, including the FID, have to be able to detect very low values. For SULEV (Super-Ultra Low Emissions Vehicle) measurements the accuracy and also the general applicability of the CVS (Constant Volume Sampling) measuring technique are now questioned. Basic understanding is necessary to ask the right questions. One important issue is the science behind the measurement principle of the FID. And in this case especially the influence of contamination of the operating gases, cross sensitivity and data processing on the Limit of Detection (LOD).
Technical Paper

Local Gaussian Process Regression in Order to Model Air Charge of Turbocharged Gasoline SI Engines

2016-04-05
2016-01-0624
A local Gaussian process regression approach is presented, which allows to model nonlinearities of internal combustion engines more accurate than global Gaussian process regression. By building smaller models, the prediction of local system behavior improves significantly. In order to predict a value, the algorithm chooses the nearest training points. The number of chosen training points depends on the intensity of estimated nonlinearity. After determining the training points, a model is built, the prediction performed and the model discarded. The approach is demonstrated with a benchmark system and air charge test bed measurements. The measurements are taken from a turbocharged SI gasoline engine with both variable inlet valve lift and variable inlet and exhaust valve opening angle. The results show how local Gaussian process regression outmatches global Gaussian process regression concerning model quality and nonlinearities in particular.
Technical Paper

Use of a Mass Spectrometer to Continuously Monitor H2S and SO2 in Automotive Exhaust

1990-02-01
900272
In studying H2S emissions, it is desirable to have an analytical technique which is rapid, continuous, accurate and easy to use in a laboratory or vehicle exhaust environment. Typically, H2S has been measured using the EPA impinger method with collection times on the order of 1 to 2 minutes. Other techniques have been developed with significantly shorter response times. However, it has been shown that the major release of H2S occurs in less than 20 seconds after a vehicle changes from rich to lean operation. Therefore, it is highly desirable to have an H2S analytical technique with a response time of less than 10 seconds. In this paper, the benefits of use of a chemical ionization mass spectrometer (CIMS) to continuously monitor H2S and SO2, emissions are reported. Using the CIMS technique, the effects of several operating parameters on the release of H2S and SO2 from automotive catalysts were studied.
Technical Paper

Data Reduction in Automotive Multiplex Systems

1994-03-01
940135
Increasing demand for utilities like navigation systems or user-defined electronic phonebooks on one hand and sophisticated engine and gear controls on the other hand leads to growing bus load between distributed local control units. This paper shows the benefits and the characteristics of various state of the art data-compression algorithms and their impact on typical automotive multiplex dataclasses. The evaluation and optimization of promising algorithms can be done via a proposed “communications prototyping”-approach. The hardware/software components of such a rapid prototyping package are outlined. Finally, first performance results of suitable data-compression measures are presented.
Technical Paper

Life-Cycle Optimization of Car Components

1995-02-01
950207
The environmental impact of the automobile and its components is of growing importance not only in public debates but also in the complex decision making process regarding future car concepts. To calculate the environmental compatibility of car components BMW has developed various quantifying instruments and a holistic Life-Cycle Analysis (LCA) approach. The development phase significantly affects the entire life-cycle of a product. Suitable design criteria, recycling requirements and in-house standards have therefore been developed and established. One of the most important objectives in optimizing the environmental compatibility of the automobile is the realization of intelligent lightweight concepts. This means one has to find the most appropriate solution in terms of ecology and economy. Due to modern development processes car manufacturers and their suppliers have to intensify their cooperation also in this area.
Technical Paper

Research Results on Processes and Catalyst Materials for Lean NOx Conversion

1996-10-01
962041
In a joint research project between industrial companies and a number of research institutes, nitrogen oxide conversion in oxygen containing exhaust gas has been investigated according to the following procedure Basic investigations of elementary steps of the chemical reaction Production and prescreening of different catalytic material on laboratory scale Application oriented screening of industrial catalyst material Catalyst testing on a lean bum gasoline engine, passenger car diesel engines (swirl chamber and DI) and on a DI truck engine Although a number of solid body structures show nitrogen oxide reduction by hydrocarbons, only noble metal containing catalysts and transition metal exchanged zeolites gave catalytic efficiencies of industrial relevance. A maximum of 25 % NOx reduction was found in the European driving cycle for passenger cars, about 40 % for truck engines in the respective European test.
Technical Paper

Energy Consumption of Electro-Hydraulic Steering Systems

2005-04-11
2005-01-1262
The reduction of fuel consumption in vehicles remains an important target in vehicle development to meet the carbon dioxide emission reduction target. One of the significant consumers of energy in a vehicle is the hydraulic power-assisted steering system (HPS) powered by the engine belt drive. To reduce the energy consumption an electric motor can be used to drive the pump (electro-hydraulic power steering or EHPS). In this work a simulation model was developed and validated to model the energy consumption of the whole steering system. This includes an advanced friction model for the steering rack, a physically modeled steering valve, the hydraulic pump and the electric motor with the control unit. The model is used to investigate the influence of various parameters on the energy consumption for different road situations. The results identified the important parameters influencing the power consumption and showed the potential to reduce the power consumption of the system.
Technical Paper

ECU Integrated DSP Based Measurement System for Combustion Analysis

2000-03-06
2000-01-0547
For development of new engines a ‘general purpose ECU’ for spark ignition engines with up to 12 cylinders has been developed. As part of this ECU a DSP (Digital Signal Processor)-based measurement unit for high frequency combustion analysis has been integrated. In this paper, details about this signal processing platform are given. The DSP-unit has 24 analog input channels. 12 channels are used for cylinder pressure measurement; the other 12 channels are general purpose ones. For example, they can be used for ionic current analysis. Additional digital inputs allow measurement of crank speed and crank speed variations. This is an important topic for misfire detection as part of the OBD regulations.
Technical Paper

Robustness and Reliability Enhancement on Retractor Noise Testing, from Development Considerations to Round Robin

2018-06-13
2018-01-1533
Sensing and acting elements to guarantee the locking functions of seat belt retractors can emit noise when the retractor is subjected to externally applied vibrations. For these elements to function correctly, stiffness, inertia and friction needs to be in tune, leading to a complex motion resistance behavior, which makes it delicate to test for vibration induced noise. Requirements for a noise test are simplicity, robustness, repeatability, and independence of laboratory and test equipment. This paper reports on joint development activities for an alternative test procedure, involving three test laboratories with different equipment. In vehicle observation on parcel shelf mounted retractors, commercially available test equipment, and recent results from multi-axial component tests [1], set the frame for this work. Robustness and reliability of test results is being analyzed by means of sensitivity studies on several test parameters.
Technical Paper

A Physical-Based Approach for Modeling the Influence of Different Operating Parameters on the Dependency of External EGR Rate and Indicated Efficiency

2018-09-10
2018-01-1736
External Exhaust Gas Recirculation (EGR) provides an opportunity to increase the efficiency of turbocharged spark-ignition engines. Of the competing technologies and configurations, Low-Pressure EGR (LP-EGR) is the most challenging in terms of its dynamic behavior. Only some of the stationary feasible potential can be used during dynamic engine operation. To guarantee fuel consumption-optimized engine operation with no instabilities, a load point-dependent limitation of the EGR rate or alternatively an adaptation of the operating point to the actual EGR rate is crucial. For this purpose, a precise knowledge of efficiency and combustion variance is necessary. Since the operating state includes the actual EGR rate, it has an additional dimension, which usually results in an immense measuring effort.
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