Automotive and Engine Technology最新文献

Water injection is one of the ways available to mitigate internal combustion engine propelled vehicles pollutions.Its practical use, yet, may require the presence of an additional liquid water tank on board, which implies new costs and constraints.In the present paper, we try to figure out whether such a tank is really needed or not. Ambient humidity, fuel chemical composition, Water–Fuel Ratio and water recycling effectiveness are combined into a water balance model of concerned engines.The obtained results are really encouraging: considering the effectivenesses of existing water recycling membranes, almost all water needs of water injection can be satisfied, without any water tank, and for most of liquid and gaseous fuels. The Exhaust Water Recirculation system presented in this paper is, thus, probably one of the key components water injection will need to be used more widely on future vehicles.

The one-dimensional computational fluid dynamics (1D-CFD) simulation is an important development tool for improving the matching process of the exhaust gas turbocharger with a combustion engine. To meet future emission requirements of commercial vehicles, an increasing focus on transient operation conditions is given. For example, a faster boost pressure build-up allows higher exhaust gas recirculation rates during load steps—improving transient nitrogen oxides ((hbox {NO}_x)) emissions. According to this, the matching process of the turbocharger focuses increasingly on the transient operation conditions of combustion engines. To increase the quality of the dynamic engine process simulation, the simulation model should be optimized with regard to the quality of the engine’s high-pressure process including emissions as well as the turbocharger modeling methodology. This paper focuses on the application of an approach that combines a data-based combustion model for the (hbox {NO}_x) and soot values and the high-pressure part of the working process with a physical description of the gas exchange. To generate the data for the combustion model, an extensive measurement campaign of all relevant parameters was carried out on a medium-duty diesel single-cylinder research engine. The developed model was integrated into a multi-cylinder engine (MCE) simulation environment and validated on the basis of corresponding MCE measurements. The sensitivities of the model were examined for the input parameters. The data-based combustion model demonstrates a high accuracy in emissions and high-pressure working process modeling both in the wide range of the engine map and under transient operating conditions as well as for different engine calibration strategies. As a result, a good baseline for the improved transient combustion simulation is provided.

In this application paper, the influence of the coolant mantle on the acoustic radiation behaviour of a hybrid drive train is investigated. This was done on an electric machine on an acoustic component test bench. The coolant mass flow around the electric machine stator was varied and then completely drained. The electrical machine remained mechanically unchanged; any variations were made to the feed pumps on the test bench side. Triaxial acceleration sensors are glued to the machine housing and reviewed as evaluation criteria. For the evaluation, the square mean value of all three spatial directions of the glued acceleration sensors was calculated. The evaluation shows that there is no significant acoustic difference between an active stator cooling jacket and a stationary stator cooling jacket. If the stator cooling jacket is pumped out empty so that air remains in it, there is a strong reduction in surface acceleration. The observations are confirmed by analytical literature values. The results presented serve as a basis for further work and developments.

In an era of rapidly changing trends and customer requirements, the necessity of agile product development processes has arisen. Currently used processes are not sustainable because they are not able to handle future volatility considering early phase requirements and would lead to late and expensive changes in product design. In the context of the automobile industry, the early phase of the product development has to deal with requirements, designing a modular vehicle architecture, which includes all models of a product family. An empirical research was conducted to generate a thorough list of production-related requirements for the chassis, between interacting departments and roles within an automotive OEM. The resulting generic model showed the interdependencies between the analysed requirements. Additionally, the aim is to measure the maturity level of the individual production-related requirements at specific phases. The first benefit of this model is to show through the interdependencies between existing production requirements, how a change would affect the system. Secondly, it is possible to measure the existing production-related issues through a maturity model, which specifies the level of completion of single components at specific phases, and thus give a value to the product development process.

Acoustics represents a quality feature of a passenger vehicle. During the first development phases, prediction tools of the acoustic performance are required to assess in the design process. A combination of numerical and experimental data provides a good compromise between accuracy and modeling effort. A key part of the airborne noise transmission chain are the different passive acoustic treatments applied to minimize the noise impact. These treatments usually include one or more layers of poroelastic media. They exhibit a highly dissipative behavior, making them suitable as noise barriers but, at the same time, complex to model. This article aims to identify the parameters that define the appropriate numerical modeling approach for vibroacoustic systems with poroelastic acoustic packages. Two different concepts for the noise reduction based on poroelastic materials have been investigated, namely the insulation through a spring–mass component and the absorption of a porous layer. The essential principles of the theory of poroelasticity are recalled and three material formulations are derived. The application range of each material model is examined with the help of two configurations: a flat plate and a simplified model of a vehicle front end. The acoustic response of the system is solved with the help of the finite element method using the different material formulations for the description of the poroelastic layers, and the results are compared to measurements conducted in a window test bench. Finally, the main findings are summarized and recommendations towards a more realistic representation of the complete transmission chain are presented.

Modern internal combustion engines (ICE) reach higher peak pressure thanks to the improved thermodynamic processes and charging technologies. Passive vibration damping approaches face challenges motivating the application of active methods. Active torsional vibration reduction achieves reduced torsional oscillations using the compensation torque generated by an electric traction machine (ETM). 48 V-based hybridization is gaining increased attention as an intermediate step towards higher levels of powertrain electrification. This trend opens new challenges for active vibration reduction with non-inline integration of the ETM using belt drive systems. We analyze the available potential for active torsional vibration attenuation in such belt drive systems in combination with a 48 V belt-driven starter generator (BSG). The study shows that a dual-mass flywheel (DMF) with a centrifugal pendulum absorber can be replaced by a simplified DMF with active vibration reduction using the 48 V BSG system. The effectiveness of active vibration reduction depends on the control functionality. In this contribution, we present an adaptive controller which does not require sensors for reference signal measurement. Besides simulative analysis, the performance of the proposed controller is demonstrated on the experimental test setup with a 2-cylinder ICE and an ETM in an inline configuration.

In the present investigation, the influence of the number of cylinders on the turbocharger and the pumping losses were determined by extensive simulations in combination with experimental investigations. The turbine efficiency is influenced by the different pulsations as a function of the number of cylinders. In addition, another very serious influence of the number of cylinders on the pumping losses has been found. This effect depends strongly on the exhaust volume before turbine, which is why the topic of constant pressure and pulse turbocharging must be considered in detail. It has been found that a smaller number of cylinders ((<4)) has higher pumping losses in principle, even with the same turbocharger efficiencies. The lowest pumping losses can be achieved with four-cylinder engines. It has also been shown that this issue is completely different for diesel and gasoline engines.

The fuel consumption of vehicles with spark-ignited (SI) gasoline engines in transient driving cycles depends greatly on the thermodynamics and its interplay with the calibration of the engine control. For the simulation of these complex phenomena covering engine physics and applied control, a new methodology is presented. A functional model of the engine control unit is introduced together with a driver control. It is coupled to a physical modeling framework consisting of a crank angle-based engine model and a vehicle drivetrain model. As a key feature, a novel predictive SI combustion sub-model is integrated, using quasi-dimensional modeling approaches for flame propagation, turbulence, and ignition delay. In a modular validation process, each sub-model and its interaction in the coupled simulation environment are evaluated successfully. The fully coupled model is then used to predict the fuel consumption in driving cycles under varying calibration strategies of the engine control.

The increasing demands for driving comfort and driving dynamics lead to the introduction of a variety of control systems in modern vehicles. So far, these systems are working in peaceful coexistence and do not use potential synergies. This paper presents a modular control allocation, which combines lateral torque distribution at the rear axle, longitudinal torque distribution, and rear wheel steering. The previous investigations of torque vectoring mostly neglected the secondary yaw torque, which is a result of the dependency between lateral and longitudinal forces at the tyres. An increase in longitudinal forces leads to a decrease in lateral forces and, therefore, results in a yaw torque. A comprehensive vehicle and tyre model is used to analyze this secondary effect for different vehicle states and requested yaw torque. The investigation shows that the influence of the secondary yaw torque varies heavily depending on the vehicle state and the requested yaw torque. Especially, for stabilizing torque requests at high lateral acceleration, the secondary effect is significant and should not be neglected. The investigation shows that an optimal distribution for each yaw torque request exists and that results in maximum lateral forces and thereby maximum lateral acceleration. These results are used within the paper’s modular control allocation. A model-based reference generator delivers desirable yaw rates and side slip angles, which are transferred into necessary lateral forces at the wheels by the control allocation unit. This force-based approach enables modular expandability and usability across multiple vehicles. The proposed controller shows that using the available systems in conjunction helps to increase driving performance and the vehicles stability at the same time.

Engine crank case designs for passenger car applications are based today on two main material technologies: grey cast iron and an increasing share of aluminium-based concepts. Due to the low wear resistance of aluminium, the latter concepts require a wear protective layer for the cylinder bore surface. Iron-based thermal spray coats are widely used for this purpose. The coating improves the tribological behaviour significantly, as previous studies have shown. Additionally, aluminium-based concepts offer advantages regarding engine weight and thermal management. The aim of the presented work was the discussion of these technological concepts regarding the tribological and sealing properties of the piston/bore interface. The study was carried out based on the AVL FRISC Floating Liner Engine. While the basic engine remained unchanged, the cylinder bore surface was varied. In addition to the floating liner friction measurement, the blow-by and lube oil consumption were also measured. A state-of-the-art multi-body dynamic simulation model complements the experimental study, while both simulation and measurement lead to similar conclusions.