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The courier express parcel service industry (CEP industry) has experienced significant changes in the recent years due to increasing parcel volume. At the same time, the electrification of the vehicle fleets poses additional challenges. A major advantage of battery electric CEP vehicles compared to internal combustion engine vehicles is the ability to regenerate the kinetic energy of the vehicle in the frequent deceleration phases during parcel delivery. If the battery is cold the maximum recuperation power of the powertrain is limited by a reduced chemical reaction rate inside the battery. In general, the maximum charging power of the battery depends on the state of charge and the battery temperature. Due to the low power demand for driving during CEP operation, the battery self-heating is comparably low under cold ambient conditions. Without active conditioning of the battery, potential regenerative energy is lost as a result of the cold battery.

More and more applications (apps) are entering vehicles. Customers would like to have in-car apps in their infotainment system, which they already use regularly on their smartphones. Other apps with new functionalities also inspire vehicle customers, but only as long as the customer can utilize them. To ensure customer satisfaction, it is important that these apps work and that failures are found and corrected as quickly as possible. Therefore, in-car apps also implicate requirements for future vehicle diagnostics. This is because current vehicle diagnostic methods are not designed for handling dynamic software failures of apps. Consequently, new diagnostic methods are needed to support the diagnosis of in-car apps. Log data are a central building block in software systems for system health management or troubleshooting. However, there are different types of log data and log environment setups depending on the underlying system or software platform.

In January 1996 Mercedes-Benz has introduced a new 4-cylinder engine OM 904 LA of the new engine family for light commercial vehicles. The power range of the OM 904 LA comprises ratings from 90 kW up to 125 kW at 2300 rpm. From the beginning of the design of this engine, a noise emission output as low as possible was strived for, aside from the high targets as far as durability, maintenace and fuel consumption are concerned. The basis is the development of noise regulations for commercial vehicles. The noise reduction measures have to be concentrated on the engine since up to now it still is one of the main noise emission sources at the vehicle. Already at the lay-out of the engine the prerequisits for a low-noise engine behaviour have been taken into consideration. The engine is equipped with a fuel injection system featuring particular unit injector pumps for each cylinder which is superior to the conventional in-line injection pump as far as acoustics are concerned.

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.

As part of a comprehensive strategic product initiative the most important commercial vehicle manufacturer - Mercedes-Benz AG - is step by step renewing its entire product range. This primarily refers to the heart of the vehicles - the engine. After the OM 457 LA, which was developed together with DDC for the special American market demands and which is produced and sold in the U.S.A. by DDC under the label “Series 55”, has had its premiere in Freightliner's Century Class, the OM 904 LA will now follow in the light commercial vehicle class. This engine has a completely new concept of a direct-injection, highly sophisticated turbocharged four-cylinder in-line engine with air-to-air intercooler, whose main characteristics can be outlined by the terms “multi-valve technology”, high-pressure injection via unit pumps” and “electronic engine control”. This “small” engine has several interesting features, which - up to now - were only known from class 8 engines.

The influence of different port designs on the generation of a swirl flow is described on the basis of stationary and non-stationary flow analyses. Subsequently, engine test bench analyses with a 3-valve one-cylinder engine were performed to assess the aforementioned port configurations with respect to their influence on the lean-burn behaviour. The most favourable port design was then used to analyse various combustion chamber shapes in order to further improve the engine behaviour during lean-burn operation and to select the most promising combustion chamber variant. Finally, the port and combustion chamber configurations thus identified were applied in vehicle simulation tests with lean-burn and EGR-burn operation to check the emission behaviour for compliance with the future European level 3 emission limits.

The problem of effectively reducing water spray formed by motor vehicles on wet roads remained up to now unsolved.Although numerous experimental investigations have been published, and comprehensive patent literature is available, the suggested solutions appear to be problematic under real-life conditions. In this paper, a configuration applicable both to commercial vehicles and passenger cars is proposed, which is restricted exclusively to the wings, and - with today's design principles - does not require any special advance preparation. A grooved channel profile in the wing causes the water spray to be reduced considerably without affecting the vehicle's suitability for everday use. An optoelectronic measuring instrument which is carried along the vehicle, makes it possible to conduct integral water spray measurements over time periods of various length.

Modern commercial vehicle engines are equipped with turbocharging and intercooling. This results in low emissions and fuel consumption. In the lower speed and load range and under transient conditions, these engines have disadvantages, as the fuel injection rate has to be limited to avoid excessive smoke emission. Also, the engine braking performance of highly charged, small displacement engines is also lower than that of large displacement engines. Mercedes-Benz decided to develop a combination of turbocharger and mechanical supercharger. In the lower speed range higher torque levels are possible and maximum torque is available without any lag especially in the transient mode with low smoke emission and fuel consumption. Vehicle performance during acceleration can be improved by up to 30%. During engine braking operation, the mechanical supercharger is activated throughout the whole engine speed range which results in a distinctive increase in braking power.

The simulation of the driving performance of motor vehicles offers the possibility of analyzing the behavior of new commercial vehicles or new systems to be integrated into the vehicle, already before the stage of the first prototypes. Thus, simulation technology may contribute to shorten the time and costs needed for the development of new vehicles and new vehicle systems. As an example, this contribution describes the simulation of a commercial vehicle with adaptive suspension elements. The simulations were used to coarse-tune the suspension elements before installation and fine-tuning them in a prototype vehicle, and to define and optimize the control strategies of electronically controlled suspension systems. A comparison between the costs of the simulation and estimated costs of corresponding field tests substantiates the economical benefits of the simulation.

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 settings of adaptive suspension elements may be switched from a comfortable “soft” characteristic to a safe and “firm” characteristic. Thus the possibility is given to not only improve the ride comfort, but the dynamic driving behavior as well, since no compromise must be made between these two criteria when tuning the suspensions. Such systems seem to be very promising for commercial vehicles, as - because of their changing loading conditions - it is very difficult to design an optimal suspension system using conventional springs and dampers. This paper describes the influence of shock absorbers and air springs with variable characteristics on the ride comfort and the dynamic behavior of a 15-t-truck by investigations done with a simulation system. A series production vehicle without adaptive suspension elements serves as basis. At first the results of measurements and simulations are compared and show a very good concurrence.

Economical and technical aspects justify intelligent suspension systems in commercial vehicles. The tasks of suspensions of vehicles are contradictionary and the prevailing problems cannot be readily solved with conventional suspension systems in a satisfying manner. However, advantages are acquired by the use of adaptive suspension systems. Varying the properties and characteristics of suspension systems in respect to the different loads transported by a commercial vehicle, to vehicle speeds and to dynamic maneuvers, nearly present as good results as closed loop controlled adaptive suspension systems do. For economical reasons fully active suspension systems are only installed in commercial vehicles performing special tasks and services. Partially active suspension systems reduce power consumption and demonstrate satisfactory efficiency.

The consequent means towards improved enhancement of the safety of commercial vehicles will in future times require more and more electronic intelligence, in case a distinct optimization of the systems will not be possible with conventional means. In forefront, endeavours are aimed at the improvements of the functions of the system in regard to driving safety, as well as driver stress relief at lowest possible costs, in order to increase the total cost effectiveness of commercial vehicles. Starting with currently implemented electronic systems up to systems now under development, a continuous development of standalone electronics up to integrated electronic compounding is the current trend. This trend shows advantages of reduced wiring and the number of sensors while it increases the function at the same time.

In particular on heavy duty commercial vehicles, the continuous braking systems “engine braking system” and “retarder”, which are independent of the service braking system, are installed to handle the continuous braking load on downhill stretches. These systems are also used to reduce lining wear and thermal loads of the service braking system. Exhaust braking systems are the most widely used form of engine braking systems. The current state-of-the-art in retarders is represented by two basic concepts, the electrodynamic retarder and the hydrodynamic retarder. A performance comparison of the different systems shows that low mountain descending speeds are the domain of engine braking systems, whereas retarders are more effective for medium and high descending speeds. The electrodynamic retarder is more favourable for lower road speeds, while the hydrodynamic retarder develops its effectiveness during higher downhill speeds.

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.

Tires of modern commercial vehicles must meet a specific requirement profile, containing the economic aspects, ride comfort and driving safety, as well. These three primary criteria are discussed in this paper, whereby emphasis is placed on the force transmission behavior of commercial vehicle tires regarded as a variable directly associated to driving safety. At the same time, the influence of distinct parameters such as wheel load, road speed, tire inflation pressure, tread depth and coefficient of adhesion between tire and road on the lateral and braking force behavior is illustrated using steady state and dynamic measurements. They were carried out on real roads using a specially prepared mobile tire dynamometer, but on an indoor drum-type tire test stand, as well. In addition to the above mentioned parameter variations the differences of the results on account of the test method are analysed.

During the most recent past, contributions to anti-lock systems have been continuously published reflecting on the multi-functional significance of these systems only in a limited way. It seems essential therefore, to compare the primary criteria of functionality to the costs precisely. The technical solutions carried into effect during the past and the present orientated towards variously different criteria of optimization. The paper illustrates the particularities of the different control systems, like 2-, 4-and 6-channel systems with Individual Control, Select-Low Control or Modified Individual Control. The impact of the various ABS-philosophies on the directional control of heavy commercial vehicles will be analyzed, using driving maneuvers like “straight-ahead braking” or “braking in a turn” on homogeneous and split adhesion road surfaces.