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Technical Paper

Electronic Data Processing Center for Engine Dynamometers

1966-02-01
660751
The dynamometer evaluation of internal combustion engines has involved a great deal of tedious interpretation and presentation of results. In the past, engine test cells have not been fully utilized, and skilled test engineers have been occupied with routine work, time which could better be spent in actual development work. This paper describes steps taken by Robert Bosch GmbH in its new engine test laboratory, to streamline procedures for observation, computation, plotting, and presentation of results. Measurements from the engine test cell are delivered electrically to a central data processing center. These data are recorded, computed electronically, and plotted on an electric plotting machine functioning from punched paper tape.
Journal Article

Next Generation Engine Start/Stop Systems: “Free-Wheeling”

2011-04-12
2011-01-0712
Engine Start/Stop systems reduce CO₂ emissions by turning off the combustion engine at vehicle standstill. This avoids the injection of fuel that would otherwise be needed simply to overcome internal combustion engine losses. As a next development step, engine losses at higher vehicle speeds are to be addressed. During deceleration, state-of-the-art engine technology turns off fuel injection as soon as the driver releases the gas pedal, thus the combustion engine is motored by the vehicle. The engine's drag torque could be desired by the driver, e.g., as a brake assist during downhill driving. However, quite frequently the driver wishes to coast at almost constant speed. Similar to Start/Stop operation, in such situations fuel is injected to simply overcome the combustion engine's drag torque. An operation mode referred to as "Free-Wheeling" reduces CO₂ emissions under such coasting conditions by disconnecting the combustion engine from the powertrain and by turning it off.
Journal Article

A Representative Testing Methodology for System Influence on Automotive Fuel Filtration

2013-04-08
2013-01-0891
Filtration of diesel and gasoline fuel in automotive applications is affected by many external and internal parameters, e.g. vibration, temperature, pressure, flow pulsation, and engine start-stop. Current test procedures for automotive fuel filters, proposed by most of the researchers and organizations including Society for Automotive Engineers (SAE) and International Organization for Standardization (ISO), do not apply the previously mentioned real-world-conditions. These operating conditions, which are typical for an automotive fueling system, have a significant effect on fuel filtration and need to be considered for the accurate assessment of the filter. This requires the development of improved testing procedures that will simulate the operating conditions in a fuel system as encountered in the real world.
Journal Article

Optical Investigations of the Ignition-Relevant Spray Characteristics from a Piezo-Injector for Spray-Guided Spark-Ignited Engines

2015-01-01
2014-01-9053
The spray-guided combustion process offers a high potential for fuel savings in gasoline engines in the part load range. In this connection, the injector and spark plug are arranged in close proximity to one another, as a result of which mixture formation is primarily shaped by the dynamics of the fuel spray. The mixture formation time is very short, so that at the time of ignition the velocity of flow is high and the fuel is still largely present in liquid form. The quality of mixture formation thus constitutes a key aspect of reliable ignition. In this article, the spray characteristics of an outward-opening piezo injector are examined using optical testing methods under pressure chamber conditions and the results obtained are correlated with ignition behaviour in-engine. The global spray formation is examined using high-speed visualisation methods, particularly with regard to cyclical fluctuations.
Technical Paper

Holistic Approach for Improved Safety Including a Proposal of New Virtual Test Conditions of Small Electric Vehicles

2015-04-14
2015-01-0571
In the next 20 years the share of small electric vehicles (SEVs) will increase especially in urban areas. SEVs show distinctive design differences compared to traditional vehicles. Thus the consequences of impacts of SEVs with vulnerable road users (VRUs) and other vehicles will be different from traditional collisions. No assessment concerning vehicle safety is defined for vehicles within European L7e category currently. Focus of the elaborated methodology is to define appropriate test scenarios for this vehicle category to be used within a virtual tool chain. A virtual tool chain has to be defined for the realization of a guideline of virtual certification. The derivation and development of new test conditions for SEVs are described and are the main focus of this work. As key methodology a prospective methodical analysis under consideration of future aspects like pre-crash safety systems is applied.
Technical Paper

Numerical and Experimental Analysis of the Mass Transfer in Exhaust Gas Sensors

2007-04-16
2007-01-1144
Within the scope of this work, the convective mass transfer to the zirconia sensor element of an exhaust oxygen sensor was analyzed experimentally and numerically. For the experimental setup, a heightened model of an oxygen sensor was built from Lucite® considering the similarity theory. Mass transfer is measured based on the absorption of ammonia and subsequent immediate color reaction. For the numerical investigation, a three-dimensional model of the test rig was built. To predict the flow pattern and the species transport inside the protection tubes, the commercial CFD-Code FLUENT® is used. The model for the mass transfer to the surface is implemented through user-defined functions.
Technical Paper

Active Pedestrian Protection - System Development

2004-03-08
2004-01-1604
Pedestrian protection is an upcoming field for research and development. Active pedestrian protection is described from a system perspective. In this view, the development of an active pedestrian protection system is shown. First an overview on statistics and legal requirements is given and the system requirements are discussed. Sensor concepts and realizations are shown, also different test methods and results are explained. FE-simulations to complete and later replace additional tests are developed, after cross check with the experimental results. In combination with the shown actuator concept this leads to a full functioning active pedestrian protection system.
Technical Paper

Luminance Measurement, Contrast Sensitivity, Homogeneity: New Approaches of Defining the Quality of Headlamps

1998-02-23
980324
The conventional measurements to describe the photometric quality of headlamps usually only comprise the luminous flux and the illuminance (resp. the luminous intensity) in several measuring points given by Type Approval Legislation. Practically, these photometric measurements do not describe the visual impression of a headlamp light distribution sufficiently, neither in lab nor in real street geometry. With the clear outer lens headlamps introduced recently, filament images are projected directly onto the screens or streets, thus giving new impulses to research. Starting from the established photometric practice, other types of measurements and physiological fundamentals will be discussed. The basic tools to make physical measurement and physiological impression comparable, e.g. in terms of homogeneity, are shown.
Technical Paper

Strategies to Reduce HC-Emissions During the Cold Starting of a Port Fuel Injected Gasoline Engine

2003-03-03
2003-01-0627
In view of tight emission standards, injection strategies to reduce raw HC-emissions during the cold starting of port fuel injected engines are evaluated in this study. The relevance of spray targeting and atomization is outlined in the first part of this paper. The foundation and performance of different injector concepts with respect to spray characteristics are discussed. Laboratory experiments demonstrate that concepts relying on auxiliary energy, such as air-assistance, fuel heating and injection at elevated system pressures, are capable of producing spray droplet sizes in the SMD-range of 25μm. For future injection strategies aimed at the compliance of SULEV emission levels, this target value is considered to be essential. In the second part of this paper, emission tests of selected injector concepts are carried out using a V6-3.2I ULEV engine operated both in a vehicle and on a test bench.
Technical Paper

Evaluating Different Measures to Improve the Numerical Simulation of the Mixture Formation in a Spark-Ignition CNG-DI-Engine

2017-03-28
2017-01-0567
Compressed Natural Gas (CNG) is a promising alternative fuel for internal combustion engines as its combustion is fuel-efficient and lean in carbon dioxide compared to gasoline. The high octane number of methane gives rise to significant increase of the thermodynamic efficiency due to higher possible compression ratios. In order to use this potential, new stratified mixture formation concepts for CNG are investigated by means of numerical fluid simulations. For decades RANS methods have been the industry standard to model three-dimensional flows. Indeed, there are well-known deficiencies of the widely used eddy viscosity turbulence models based on the applied Boussinesq hypothesis. Reynolds stress turbulence models as well as scale resolving simulation approaches can be appealing alternative choices since they offer higher accuracy. However, due to their large computing effort, they are still mostly impractical for the daily use in industrial product development processes.
Technical Paper

Speech-Controlled Wearable Computers for Automotive Shop Workers

2001-03-05
2001-01-0606
Vehicle inspection in repair shops is often still based on paper forms. Information Technology (IT) does not yet support the entire inspection process. In this paper, we introduce a small wearable IT device that is controlled by speech and enables service technicians to wirelessly access relevant data and to perform on-site communication. Users can carry this device in a pocket and use a small headset to enter speech and receive audio feedback. This system provides a completely speech-enabled functionality and thus offers a hands-free operation. After showing the applicability of wearable computers in this environment, we developed a proprietary hardware system consisting of a thin-client connected via a Digital Enhanced Cordless Telecommunications (DECT) link to a standard Personal Computer (PC) that runs a speech engine and hosts a database. Several field tests in garages helped us during the evolution of our prototypes where service technicians critiqued the prototypes.
Technical Paper

Variable Orifice Geometry Verified on the Two-Phase Nozzle (VRD)

1995-02-01
950081
Innovative solutions for reducing particulate emissions will be necessary in order to comply with the even more stringent exhaust-gas standards of the future. The potential of a diesel nozzle with variable orifice geometry has long been common knowledge in the area of engine construction. But up to now, a fully functional solution of such a nozzle has not appeared which operates with a reduced orifice at low engine speeds and/or low loads. Here with regard to target costing, the requirements implicit in function and manufacture must also be taken into account. Using calculations on nozzle interior flow and injection-spray investigations, it will be shown which nozzle geometries best fulfill the various requirements. In order to achieve low levels of particulate emission in an engine with a combustion chamber designed for optimum use of a hole-type nozzle, the injection-spray direction and its geometry must to a large extent correspond to those of a hole-type nozzle.
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