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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.

In this paper, the differences between a production car of the 2018 A-class and an early stage vehicle model with a mostly similar outer skin are examined experimentally and numerically. The aerodynamic development of vehicles at Mercedes-Benz is divided into several phases. When comparing force coefficients differences can be observed between these distinct hardware stages as well as when comparing steady state simulations to wind tunnel measurements. In early phases when prototype vehicles are not yet available, so-called aero foam models are used. These are well-defined full-sized vehicle models, as the outer skin is milled from Polyurethane. Important aerodynamic characteristics such as a motor compartment with a cooling module, deflecting axles with rotatable wheels and underbody covers are represented.

Increasing combustion pressure, low viscosity oils, less oil supply and the increasing stress due to downsizing of internal combustion engines (ICE) lead to higher loads within the bearing. As the mechanical and tribological loads on the piston pin bearings have a direct impact on the service life and function of the overall engine system, it is necessary to develop a robust tribological design approach. Regarding the piston pin bearing of a diesel engine, this study aims to describe the effects of different parameters on a DLC-coated piston pin within the bearing. Therefore, an external engine part test rig, which applies various forces to the connecting rod and measures the torque on a driven pin, is used to carry out validation measurements. The special feature of the test bench is the way the piston is beared. For the first experiments, the piston crown is placed against a plate (plate-bearing); later, this plate-bearing is replaced by a hydrostatic bearing.

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.

The shifting comfort of automatic transmissions of diesel engines at low temperatures can be substantially improved by using springs with temperature dependent rates in the control valves. These springs utilize the shape memory effect of Ni-Ti alloys. They provide a simple and economic way to control both shifting pressure and shifting time. The Mercedes- Benz automatic transmission uses two different springs with thermovariable rate (TVR) in the shifting pressure system to adapt the pressure in the switching elements to the lower torque of cold diesel engines. One spring is used in the shifting pressure control valve and one in the accumulator system.

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.

During the past few years, economy of commercial vehicles has increased considerably due to higher engine outputs a+ lower engine speeds together with enhanced fuel economy. However, the average speed of commercial vehicles is not only determined by the speed attainable on level ground and on uphill gradients, but also to a large extent by the speed attainable on downhill gradients, with the latter depending on the available constant braking power. Since the displacement of commercial vehicle engines has not been increased or has even become smaller, their braking power has increased only slightly ot not at all. In order to enhance the overall economy of commercial vehicles, it was therefore necessary to increase the engine braking performance as well since the wheel brakes cannot be used for constant braking and additional systems for continuous operation are very complex.

During recent years there has been a continuing increase in the demands for higher braking performance of commercial vehicle engines. Mercedes-Benz had introduced the engine brake with continuously open decompression valve (‘Konstantdrossel’) into series production in 1989 as an option (1). A further increase of braking power was to be achieved while retaining the additional decompression valve in the cylinder head. For this, the decompression valve was no longer kept open during the whole working cycle (continuously open decompression valve), but only for a short period from just before compression TDC to about 90...120° crank angle after compression TDC (pulsed decompression valve). The hydraulic actuating system which opens and closes the decompression valves was developed in cooperation with Mannesmann-Rexroth GmbH, Lohr, Germany. The engine braking performance attainable with this system is shown in comparison to other known engine braking systems.

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.

Load control by means of early intake valve closing (EIVC) permits brake mean effective pressure (BMEP) to be improved by as much as 14 % at full load and pumping losses in part load to be reduced comparable to the unthrottled engine. Concomitant to this, though, the marginal conditions for good mixture formation and part load combustion optimized for efficiency are greatly impaired. With ideal mixture formation, improvements in specific part load consumption (BSFC) of the order of 8 to 12 % are achievable. The mixture formation which occurs at low part load in the combustion chamber itself is not effective as the charge motion induced by the inflow process with EIVC dies away rapidly and at the same time fuel still condenses. The inhomogeneities to which this gives rise impair ignition conditions and the combustion pattern, which greatly limits the actual useful work of the theoretical charge cycle benefit.

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.