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The selective catalytic reduction (SCR) based on urea-water-solution is an effective technique to reduce nitrogen oxides (NOx) emitted from diesel engines. A 3D numerical computer model of the injection of urea-water-solution and their interaction with the exhaust gas flow and exhaust tubing is developed to evaluate different configurations during the development process of such a DeNOx-system. The model accounts for all relevant processes appearing from the injection point to the entrance of the SCR-catalyst: momentum interaction between gas phase and droplets evaporation and thermolysis of droplets hydrolysis of isocyanic acid in gas phase heat transfer between wall and droplets spray/wall-interaction two-component wall film including interaction with gas phase and exhaust tube The single modeling steps are verified with visualizations, patternator measurements, phase-doppler-anemometer results and temperature measurements.

Passenger car DI Diesel engines need a flexible fuel injection system. Bosch develops a common rail system for this purpose. Besides variation of fuel quantity and start of injection, it permits to choosing freely injection pressure inthe rangeof 150 to 1400 barand injecting fuel in several portions. These new means will contribute to further improvements of DI engines concerning noise, exhaust emissions and engine torque.

Salt Spray Test is being used since 1930’s to accelerate the corrosion testing of materials and to understand the longevity of applied coating. The sample in this kind of test is exposed to a salt mist in a controlled environment and its corrosion resistance is evaluated by measuring the corrosion rate. The Wet-Dry cycle in Salt Spray Test has the ability to simulate the drying and wetting which occurs in real driving scenario, leading to formation of a film of corrosion products which is useful in analyzing the kinetics of electrochemical reaction. Despite the advancement in severity of these tests to understand the atmospheric corrosion phenomena, they still consume time and resources. Secondly, sometimes these kind of tests do not consider into account the effect of Temperature, Humidity and other chemicals in play. Thus, numerical simulation plays a pivotal role in digitalizing the corrosion analysis to a certain extent.

The objective was to develop a modem engine to succeed the M 102; 2.6 million of these units were made between 1979 and today making it the most successful Mercedes-Benz four-cylinder petrol engine to date. The new M 111 coordinated production set-up together with the familiar M 104 six-cylinder four-valve engines and the 600 diesel series. Emphasis has been deliberately given to improved torque rather than very high volumetric efficiency. This has made it possible to apply four-valve technology, which was originally only to be found in motor racing, in such a way that ordinary customers can benefit form advantages such as high torque and raised power output, as well as reduced fuel consumption and emissions. Extensive noise-reducing measures in the engine ensure that, despite the higher power output and lower engine weight, noise levels have also been improved.

The automotive world is progressing fast towards autonomous vehicles making sensors one of the critical components. There is a requirement for constant exchange of information between the vehicle and its surrounding environment, which is assisted by sensors such as Camera, LiDAR, and RADAR. However, exposure to harsh environmental conditions such as rain, dirt, snow, and bird droppings can hamper the functioning of the sensors and in turn interrupt accurate vehicle maneuvers. Sensor-cleaning mechanisms are required to be tested under various weather conditions and vehicle operating situations. Besides wind tunnel tests, digitalizing this whole process becomes important to take decision on design changes in early vehicle development stage. This work presents a digital methodology to test the LiDAR cleaning system in the advent of mud clearing at different vehicle speeds. The cleaning mechanism consists of a telescopic nozzle placed above the LiDAR translating back and forth.

Sunroof buffeting is examined experimentally and numerically in this paper. Despite the fact that some consider the simulation process for sunroof buffeting to be mature, there remain substantial uncertainties even in recently published methodologies. Capturing the frequencies and especially the sound pressure levels correctly is essential if CFD simulations are intended to be used during early stages of a car development process. Numerous experimental results of sunroof buffeting and the interior low-frequency characteristics of a 2013 Mercedes-Benz S-Class have been used to develop a simplified car model: a full-size S-Class model with slightly simplified geometries in the interior as well as at the exterior. To avoid the effects of numerous different materials in the interior, it is solely made from polyurethane and aluminum and built to maximize its structural rigidity and air-tightness.

The design of ABS- or vehicle control systems by means of computer simulation needs adequate tire models. Recordings of the wheel speed during ABS control show oscillations caused by the rapid pressure changes in the wheel brake cylinder. Investigations in lateral tire dynamics show a phase shift between the slip angle and the lateral tire force. These transients can not be explained by simulation if the usual stationary tire input-output behaviour is supposed. Thus the investigation of the oscillations requires a different approach to the modelling of the tire. In a first step measurements with an experimental car equipped with a computer for data acquisition and control and with various sensors - e.g. a Rotating Wheel Dynamometer - were carried out. The measurement results showed a correlation between the oscillations in the wheel speed and the braking force caused by the pressure pulses as well as high frequency oscillations in the lateral tire forces.

In the last years, the requirements for electrical energy systems in motor vehicles have increased considerably. In the past, many studies were focused on single components of the electrical system. However, to shorten the development process, reduce costs, improve reliability and also to optimize the fuel consumption due to the electrical system, the electrical system must be regarded as a whole. The Robert Bosch GmbH has developed a simulation environment, which is intended to improve the development process of new vehicle electrical systems by means of computer simulation. On the basis of a freely selectable driving cycle and various driver models, it is possible to simulate the behavior of electrical energy supply structures. The model of the electrical system is coupled to a dynamic model of the drivetrain. The characteristics of this drivetrain can also be modified and various vehicle models can be selected for simulation.

The current automotive market is dynamic, leading to complex functionalities being incorporated into the control software of various components like engine, gearbox, battery, E-motor etc. This results in utilization of virtual environments for software testing to reduce the development time. The virtual platforms under the category X-in-the-Loop (XiL) e.g. Software-in-the-Loop (SiL) and Hardware-in-the-Loop (HiL) use simulated models to achieve a desired test goal. These component models must be rigorously validated to ensure the quality of XiL-Testing. Thus, it is essential to define a model release process that maintains model quality irrespective of the modeling approach used and the user. One of the challenges is to choose an appropriate Error Metric (EM) that sets criteria for model release. This paper proposes a combination of Theil’s Inequality Coefficient (TIC) and Unscaled Mean Bounded Relative Absolute Error (UMBRAE) as the EM.

Acoustics and vibrations are amongst the foremost indicators in perceiving the quality of drive units. Analyzing these factors is vital for improve the performances of electro-mechanical systems. This paper deals with the study of vibro-acoustic behavior concerning the drivetrain components using system modeling and Finite Element calculations. A generic simulation methodology within system modeling is proposed enabling the vibro-acoustic simulation of electro-mechanical drivetrains. Excitations for these systems mostly arise from the electric motor and mechanical gears. The paper initially depicts the system model for gear whining considering the associated nonlinearities of the mesh. The results obtained from the gear mesh submodel, together with the excitations resulting from the motor, aid in the comprehension of the forces at the bearings and of the vibrations at the housings.

The paper describes a predictive tool for the determination of air and coolant temperatures and heat exchange resulting from the operation of heat exchangers, e.g., radiator or air-conditioner condenser in the underhood of automotive engines. The paper describes a detailed computational model where both the fluid streams are numerically solved and the phase change of the refrigerant is taken into account in a condenser simulation. An actual underhood simulation with interactions with a radiator is presented. A numerical simulation for a condenser is also presented. Reasonable agreement is shown with the test data.

The real-time concentrations of benzene, toluene, xylene, trimethyl-benzene and naphthalene in vehicle exhaust have been monitored during the FTP-cycle with a time-resolution of 20 ms and a sensitivity of 50 ppb. Using a laser mass spectrometer, the aromatic hydrocarbons in unconditioned exhaust gas at sampling positions behind the exhaust valve, before and behind the catalytic converter have been analyzed. The comparison of the emissions sampled before and behind the catalytic converter reveals the effect of dealkylation of the aromatic hydrocarbons in the catalytic converter. Whereas most of the aromatic hydrocarbons are burned in the hot catalytic converter, however, bursts of aromatic hydrocarbons are released at transient motor operation. In these moments, which can be attributed to phases of closed throttle valve and very low engine load at gear changes, a significant part of the C1-, C2- and C3- benzenes has been converted into benzene.

Secondary air injection after cold start gives two effects for reduced exhaust emissions: An exothermic reaction at the hot exhaust valves occurs, which increases the temperature of the exhaust gas. It gives sufficient air to the catalyst during the cold start fuel enrichment that is necessary to prevent driveability problems. Handicaps for the wide use of air injection include space constraints, weight and price. An electrical air blower was choosen to best satisfy all these requirements. The development steps are described. The result is a three stage radialblower with extremly high revolutions of about 18000 rpm. The system configuration and the outcome are demonstrated on the new C-Class of Mercedes-Benz. The results show emission reductions higher than 50 %, while also satisfying the development goals of noise, volume, weight and cost requirements.

A new automotive active safely system, the Vehicle Dynamics Control System (VDC) of BOSCH was introduced on the market in 1995. Besides improving the ABS/ASR functions, VDC will also actively support the driver in critical situations of lateral vehicle dynamics. This system includes new ABS/ASR-control algorithms and a superimposed control algorithm, the vehicle dynamics controller. Furthermore, an extension of the standard ABS/ASR-hydraulic system was necessary as well as the development of new automotive sensors. During all phases of the interdisciplinary system development, tests on experimental cars and extensive computer simulations were used in parallel. In order to provide adequate simulation models for different tasks, a modular concept for the simulation tool is important. Furthermore, a transparent and portable application of the control algorithm for both, experiment and simulation, is required.

The article describes the methods, which are employed in order to ensure high performance, safety and quality of ABS and ASR. System behaviour is evaluated and optimized by computer simulation. Moreover, a real-time simulator has been developed by which the consequences of hardware defects can be investigated systematically, Despite the increasing use of simulation the testing of vehicles remains the most important tool for system evaluation. For that purpose, a digital data acquisition system has been developed and objective evaluation criteria have been established. In order to achieve high product quality the Failure Mode and Effect Analysis (FMEA) is carried out at an early phase of development. Another prerequisite for high product quality is thorough durability and endurance testing before release of production.

After the introduction of four-valve technology for gasoline powered passenger cars, Mercedes-Benz consistently developed this technology also for Diesel engines. Based on the proven success of the prechamber combustion system, this new Diesel engine generation, which includes 4, 5 and 6-cylinder naturally-aspirated engines, will be the first four-valve Diesel engines to be installed in passenger cars. The naturally aspirated 3.0 liter 6-cylinder in-line engine which represents the high end of this generation will be offered for sale in all 50 states of the USA in the Executive Class models starting on January 1, 1994. Four-valve technology allows the prechamber to be located centrally between the intake and exhaust valves which results in a major improvement of the combustion process. In addition, this 6-cylinder engine has a resonance intake system controlled by two butterfly valves to maximize the volumetric efficiency of the engine.

Since the brake colloquium in 2004 the role of climatic conditions and their relations to noise occurrence, sound pressure level and friction coefficient level is widely discussed in the US and European working groups on brake noise. A systematic study has been started to investigate the influence of relative humidity, absolute humidity and temperature on brake noise and the corresponding friction coefficient level. In this study an enormous effort was taken to keep the influences of the brake parameters, e.g. lining material, Eigenfrequencies and dimensions of the different components as small as possible to investigate the climatic influence only. Strategic humidity and temperature levels were tested according to the Mollier-Entropy-Enthalpy-Diagram which are corresponding to the seasons in the various international regions. A regression analysis evaluates the correlation and the influence of each parameter to noise and friction coefficient level.

Computational models directly derived from data gained increased interest in recent years. Data-driven approaches have brought breakthroughs in different research areas such as image-, video- and audio-processing. Often denoted as Machine Learning (ML), today these approaches are not widely applied in the field of vehicle Noise, Vibration and Harshness (NVH). Works combining ML and NVH mainly discuss the topic with respect to psychoacoustics, traffic noise, structural health monitoring and as improvement to existing numerical simulation methods. Vehicle interior noise is a major quality criterion for today’s automotive customers. To estimate noise levels early in the development process, deterministic system descriptions are created by utilizing time-consuming measurement techniques. This paper examines whether pattern-recognizing algorithms are suitable to conduct the prediction process for a steering system.

The valve timing of internal-combustion engines usually represents a compromise with regard to the requirements placed on power output and torque. This paper describes the development of a system for variable valve timing, taking the new Mercedes-Benz 4-valve engines as an example. Gas exchange calculation and tests carried out on a modified 4-cylinder engine have demonstrated that with two intake valve times and one specified exhaust valve time virtually the best possible torque characteristics combined with high power output can be achieved. Intake valve timing is adjusted dependent on load and engine speed by turning the intake chamshaft using a hydraulic-mechanically acting camshaft adjuster, whose functional principles are described in detail.

This paper presents the Vehicle Dynamics Control (VDC) for commercial vehicles developed by BOSCH. The underlying physical concept is discussed in the second section after a short introduction. The third section shows the computer simulation used in the development process. Section four describes the controller structure of the VDC system. In Section five the use and effectiveness of VDC for commercial vehicles is shown in different critical driving situations. This is done by using measured data collected during testing (lane change, circular track) and it demonstrates that the safety improvements achieved for passenger cars are also possible for commercial vehicles.