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The steady increase of engine power and the demand of lightweight design along with enhanced reliability require an optimized dimensioning process, especially in cylinder head valve bridge, which is progressively prone to cracking. The problems leading to valve bridge cracking are high temperatures and temperature gradients on one hand and high mechanical restraining on the other hand. The accurate temperature estimation at the valve bridge center has significant outcomes for valve bridge thickness and width optimization. This paper presents a 1D heat transfer model, which is constructed through the cross section of the valve bridge center by the use of well known quasi-stationary heat convection and conduction equations and reduced from 3D to 1D via regression and empirical weighting coefficients. Several diesel engine cylinder heads with different application types and materials are used for model setup and verification.

This paper introduces the new 1.6L engine family, designed and developed by the Chrysler group of DaimlerChrysler Corporation in cooperation with BMW. An overview of the engine's design features is provided, with a detailed review of the performance development process with emphasis on airflow, combustion, thermal management and friction. This information is presented, to provide an understanding of how the engine simultaneously achieves outstanding levels of torque, power, fuel consumption, emissions and idle stability. The use of analytical tools such as Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) in the optimization of the engine is shown.

In the present study, the exterior air flow over convertibles together with the interior flow in the passenger compartment has been calculated using the commercial CFD program STAR-CD. The investigations have been performed for a SLK-class Mercedes with two occupants. The computational mesh consists of about 3 million hexahedra cells. The detailed informations of the calculated flow field have been used to elaborate the characteristic flow phenomena and increase the physical understanding of the flow. The influence of different geometrical modifications (variations of roof spoiler, variations of the draft stop behind the seats etc.) on the flow field and the air draft experienced by the occupants has been analyzed. To proof the accuracy of the numerical results, wind tunnel experiments in a full scale and 1:5 scale wind tunnel have been carried out for the basic car model as well as for several geometrical variations.

In the present study, the thermal comfort in a convertible has been evaluated using the in-house program TEKOS. The investigations have been performed for a SLK-class Mercedes with two occupants. The computational mesh consists of about 3 million hexahedra cells. TEKOS has been adapted to open driving conditions. The influence of the air-conditioning system and of different draft stops on the thermal comfort has been investigated in an autumn case. The study has shown, that in a basic case without draft stop and air conditioning the evaluation results in very poor thermal comfort values at the whole body, especially at unclothed parts of the body. If a draft stop and maximum heating is regarded, almost all parts of the body are close to the comfort range except of the head region. With TEKOS it is possible to quantify the influence of different parameters on the thermal sensation in convertibles with the advantage of an objective thermal evaluation.

Today's interior systems engineer has been challenged with providing cost-effective instrument panel design solutions to meet NHTSA's new FMVSS 208 front crash regulations. Automotive manufacturers are in continuous search of newer methods and techniques to reduce prototype tests and cost. Analytical methods of predicting occupant and structural behavior using computer-aided engineering (CAE) analysis has been in place for quite some time. With the new FMVSS 208 regulations requiring both 5th and 50th percentile occupant testing, CAE analysis of predicting occupant response has become increasingly important. The CAE analyst is challenged with representing the barrier test condition, which involves the structure and the occupant moving at velocities of 25, 30 and 35 mph. Representing the cab kinematics in high-speed impacts is crucial, since capturing the vehicle intrusion and pitching should be made part of the input variables.

Both, the continuous strengthening of the exhaust emission legislation and the striving for a substantial reduction of carbon dioxide output in the traffic sector depict substantial requirements for the development of future diesel engines. These engines will comprise not only the mandatory diesel oxidation catalyst (DOC) and particulate filter DPF but a NOx aftertreatment system as well - at least for heavier vehicles. The oxidation catalysts as well as currently available NOx aftertreatment technologies, i.e., LNT and SCR, rely on sufficient exhaust gas temperatures to achieve a proper conversion. This is getting more and more critical due to the fact that today's and future measures for CO₂ reduction will result in further decrease of engine-out temperatures. Additionally this development has to be considered in the light of further engine electrification and hybridization scenarios.

This paper describes a method to simulate underhood temperature distributions in passenger cars. A simplified engine compartment simulation test rig is used to perform measurements with well known boundary conditions to validate the simulation strategy. The measurement setup corresponds to idle without working fan. The aim of this setup is to validate cases with strong natural convection, e.g. thermal soaking. A coupled steady-state CFD run and thermal analysis is undertaken to simulate the temperature distribution in the test rig. Convective heat transfer coefficients and air temperatures are calculated in StarCD™. The radiative and conductive heat transfer is considered in a RadTherm™ analysis. The strong coupling of flow field and wall temperature in buoyancy driven flows requires an iterative process. Calculated temperatures are compared to measured results in order to validate the simulation method as far as possible. Some of the results are reported in this paper.

In the present paper, first results of an extensive and ongoing parametric study are shown. The objective of the parametric study is to clarify the influence of relevant flow and geometrical parameters on the microclimate and thermal comfort of the occupants. Flow parameters included in the study are air mass fluxes, velocity magnitude, air temperature and inflow direction at the vents. Geometrical parameters of interest are number, location, area and shape of the air vents as well as geometrical details of the passenger compartment itself. The parametric study is performed numerically on the basis of a computational model for a passenger compartment of a Mercedes E-Class sedan. The numerical method used has been published earlier and consists of a system of three programs for simulating the flow and temperature field in the cabin, the heat transfer and radiation and the thermal sensation of the occupants.

Thermal management describes measures that result in the improved engine or vehicle operation in terms of energetics and thermo mechanics. In this context the involvement of the entire power train becomes more important as the interaction between engine, transmission and temperature sensitive battery package (of hybrid vehicles or electric vehicles with range extender) or the utilization of exhaust gas thermal energy play a major role for future power train concepts. The aim of thermal management strategies is to reduce fuel consumption while simultaneously increasing the comfort under consideration of all temperature limits. In this case it is essential to actively control the heat flow, in order to attain the optimal temperature distribution in the power train components.

The fuel consumption and the emissions of modern passenger cars are highly affected by the fluid and material temperatures of the engine. Unfortunately, the high thermal efficiencies of Direct Injection (DI) Diesel and Spark Ignition (SI) engines cause in many driving situations low heat transfer to the engine components and especially to the oil and the coolant. In these conditions the normal operating temperatures are not achieved. Especially at low ambient temperatures and low engine loads the requirement of a comfortable cabin heating and a fast warm-up of engine oil and coolant cannot be satisfied simultaneously. To reach the required warm-up performance, an Exhaust Heat Recovery System (EHRS) will be demonstrated. Further design and optimization processes for modern cooling systems in fuel-efficient engines require numerical and experimental investigations of supplemental heater systems to meet all requirements under all circumstances.