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Tapping of one or more torques (ranges 10 Nm and 60 Nm) on the steering column for the purpose of servo control must satisfy high accuracy requirements on the one hand and high safety requirements on the other hand. A suggestion for developing a low-cost solution to this problem is described below: Strain gages optimally satisfy both these requirements: However, for cost reasons, these are not applied directly to the steering column but to a prefabricated, flat steel rod which is laser welded to the torque rod of the steering column. The measuring direction of the strain gages is under 45° to the steering column axis. The strain gages are either vacuum metallized onto the support rod as a thin film or laminated in a particularly low-cost way by means of a foil-type intermediate carrier.

Rear axle steering systems electronically controlled and hydraulically actuated are discussed for commercial vehicles. With these steered axles, the major objective is to improve the manoeuvrability of these vehicles. With the aid of the steering strategy “Rear end Swing-out Compensation” it will be assured, that in two-axle, all-wheel steering trucks dangerous rear end swing-out effects, occuring primarily in low speed ranges, will not take place. In addition, it is possible to enhance the dynamic stability of two-axle trucks while braking on split adhesion road surfaces with the aid of specific control algorithms. Furthermore, the application of a rear axle steering system can suppress dangerous lateral oscillations of centre-axle trailers.

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.

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.

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.

Additional future requirements for automobiles such as improved vehicle dynamics control, enhanced comfort, increased safety and compact packaging are met by modern electrical steering systems. Based on these requirements the new functionality is realized by various additional electrical components for measuring, signal processing and actuator control. However, the reliability of these new systems has to meet the standard of today's automotive steering products. To achieve the demands of the respective components (e.g. sensors, bus systems, electronic control units, power units, actuators) the systems have to be fault-tolerant and/or fail-silent. The realization of the derived safety structures requires both expertise and experience in design and mass production of safety relevant electrical systems. Beside system safety and system availability the redundant electrical systems also have to meet economic and market requirements.

The prime factor which influences noise and vibrations of electro-mechanical drives is wear at the components. This paper discusses the numerical methods developed for abrasion, vibration calculations and the coupling between wear and Noise Vibration and Harshness (NVH) models of the drive unit. The vibration domain model, initially, focuses on the calculations of mechanical excitations at the gear shafts which are generated via a nonlinear dynamic model. Furthermore, the bearings are studied for the influences on their stiffness and eventually their impact on the harmonics of the drivetrain. Later, free and forced vibrations of the complete drivetrain are simulated via a steady-state dynamic model. Consequently, the paper concentrates on the abrasion calculations at the gears. Wear is a complex process and understanding it is essential for determining the vibro-acoustics characteristics.

Meta material has been known for many years and the physics are well known since decades. But the challenge has always been to put the know how into (mass) production. This was the reason why no meta material has found its way into the automotive industry so far. But now things have changed: meta material became Meta Design and is going into serial production in 2024. Meta Design is a tunable spring mass system with foam acting as the spring and heavy layer as the mass. Meta Design is characterized by cavities in the foam and concentrated masses of the heavy layer as functionalized mass pins. By tuning the size of the cavities and the weight of the mass pins the acoustic performance can be adjusted to the requirements of each individual car line. After preliminary simulations, flat samples were tested in the lab. The next step was launched: the production and testing of a handmade prototype part of a firewall insulation for a Mercedes-Benz A-Class.

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 new generation of drive-by-wire systems currently under development has demanding requirements on the electronic architecture. Functions such as brake-by-wire or steer-by-wire require continued operation even in the presence of component failures. The electronic architecture must therefore provide fault-tolerance and real-time response. This in turn requires the operating system and the communication layer to be predictable, dependable and composable. It is well known that this properties are best supported by a time-triggered approach. A consortium consisting of German and French car manufacturers and suppliers, which aims at becoming a working group within the OSEK/VDX initiative, the OSEKtime consortium, is currently defining a specification for a time-triggered operating system and a fault-tolerant communication layer.1 The operating system and the communication layer are based on applicable interfaces of the OSEK/VDX standard.

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.

Vibration testing is often carried out for automotive components to meet guidelines based on their operational environments. This is an iterative process wherein design changes may need to be made depending on an intermediate model’s dynamic behavior. Predicting the behavior based on modifications in boundary conditions of a well-defined numerical model imparts practical insights to the component’s responses. To this end, application of a general method using experimental free-free condition frequency response functions of a structure is discussed in the presented work. The procedure is shown to be useful for prediction of responses when kinematic boundary conditions are applied, without the need for an actual measurement. This approach is outlined in the paper and is applied to datasets where dynamic modifications are made at multiple boundary nodes.

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.

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.

Actual research results in the automotive field show that there is a big potential in increasing active and passive safety by implementing intelligent driver assisting systems. Realizing such safety related system functions requires an electronic system without mechanical or hydraulic backup to de-couple the human interface from the vehicle functions, e.g., steering and braking. Safety critical functions without mechanical backup enforce new requirements in system design. Any faulty behavior of a component within the system must not lead to a malfunction of the overall system. Consequently in the system design fault-tolerance mechanisms in real time must be introduced. Active replication of a functional node is a proper solution to guarantee this real time fault-tolerance. Redundancy management of the functional nodes can be implemented by fail-silent replicas, i.e. a node behaves correctly or does not produce any output at all.

This paper presents the conceptual model and the fundamental mechanisms for software development in the context of the Brite-EuRam project Safety Related Fault Tolerant Systems in Vehicles (nick-named X-By-Wire). The objective of the X-By-Wire project is to achieve a framework for the introduction of safety related fault tolerant electronic systems without mechanical backup in vehicles. To achieve the required level of fault-tolerance, an X-By-Wire system must be designed as a distributed system comprising a number of fault-tolerant units connected by a reliable real-time communication system. For the communication system, the time-triggered TTP/C real-time communication protocol was selected. TTP/C provides fault-tolerance message transfer, state synchronization, reliable detection of node failures, a global time base, and a distributed membership service. Redundancy is used for masking failures of individual processor nodes and hardware peripherals.

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.