Automotive and Engine Technology最新文献

The increasing number of functions in modern vehicle leads to an exponential increase in software complexity. The validity and reliability of all components must be ensured, making the use of appropriate vehicle diagnostics systems indispensable. The purpose of such systems is to collect and process data about the vehicle. To find issues during vehicle development, the OEMs will usually have a development fleet of thousands of vehicles. The challenge for diagnostic systems is to detect issues during these tests, as well as collecting as much data as possible about the circumstances that led to the fault. A single-vehicle produces hundreds of gigabytes of data per month. The required data bandwidth cannot be fulfilled by current mobile network subscriptions as well as WIFI or cable-based infrastructure. This limits the amount of data that can be collected during field tests and hinders big data analysis like AI training or validation. Hence a software solution for data reduction is necessary. The authors present a method for data handling that drastically reduces the amount of data consumption and optimizes the transfer delay between a remote-diagnostic systems and the cloud. Using a pipeline of data preprocessing as well as an established compression algorithm, the amount of transmitted data is reduced by a factor of nearly ten. This method will allow to collect more data in field testing and improve the understanding of issues during vehicle development.

The motion control of autonomous vehicles with a modular, service-oriented system architecture poses new challenges, as trajectory-planning and -execution are independent software functions. In this paper, requirements for an encapsulated trajectory tracking control are derived and it’s shown that key differences to conventional vehicles with an integrated system architecture exist, requiring additional attention during controller design. A novel, encapsulated control architecture is presented that incorporates multiple extensions and support functions, fulfilling the derived requirements. It allows the application within the modular architecture without loss of functionality or performance. The controller considers vehicle stability and enables the yaw motion as an independent degree of freedom. The concept is applied and validated within the vehicles of the UNICARagil research project, that feature the previously described system architecture to increase flexibility of application by dynamically interconnecting services based on the current use-case.

Piston rings cause significant friction losses within internal combustion engines. Especially the first compression ring, which is pressed onto the liner by high cylinder pressure, contributes significantly to the total friction loss of the piston assembly. The tribological behavior of the oil scraper ring is mainly related to the pretensioning force and can lead to high losses even at low and idle speed. Due to this, there is always a markable risk of wear for the contact surfaces of the piston rings and the cylinder. “Diamond-like carbon” coatings on the surface of the piston rings can prevent wear and are able to reduce friction in the ring-liner-contact. The purpose of this work was to investigate the tribological benefit of this coating-system on the compression and oil scraper ring. Experimental studies were carried out on a fired single-cylinder engine using the Indicated Instantaneous Mean Effective Pressure-method (IIMEP) for the crank angle-resolved detection of the piston assembly’s friction force. To be able to determine the component-related fractions of the friction loss and to quantify the hydrodynamic and asperity related parts locally and time dependent, an EHD/MBS model of the engine was created in AVL EXCITE and a simulative investigation was performed. This simulation was validated by the experimental work and provided detailed information about the individual contact conditions and gap height of each tribological contact of the piston group. The combined approach of measurement and simulation enabled the prediction of tribological aspects and performance in parameter studies on a virtual engine test bed.

The spread of all-electric drives is steadily increasing in all sectors of road transport. Due to the constantly increasing demands on efficiency and performance by legislation and customers, it is necessary to continuously push the system limits of the powertrains. This paper presents an approach that performs an initial thermal system analysis based on a first gearbox configuration and efficiency calculation. Here, the componentwise loss calculation is used to identify thermal hotspots within the gearbox stage. The basis of this analysis is the thermal network method. For the approach, the gearbox elements gear, bearing, shaft, seal and housing are broken down into standard thermal elements to be created automatically for any subsequent gearbox configuration. The linking of these elements to each other is also standardised and automated comparably. An extensive simulation study is carried out using the smoothed particle hydrodynamics method to consider the load point-dependent oil distribution, which enables an initial estimate of the oil distribution. The thermal network filled in this way is then solved on a time-step basis, allowing dynamic load cases to be considered. The quality of the method is validated within the paper using the VW ID 3 gearbox as an example. Due to the use of a series gearbox, the validation was carried out on the basis of the accessible housing temperatures. These already show good convergence of the method compared to other existing approaches, which reinforces the necessity of conducting further experimental studies.

In this work, a shock tower of a mid-size vehicle using steel (St)–aluminium (Al) hybrid-casting technology was developed with current shock towers as a benchmark. The use of this hybrid-casting technology, which features a ductile material connection between steel and cast aluminium, makes it possible to combine the design advantages of cast aluminium with the mechanical properties of high-strength steels. Based on this combination, a new shock tower concept was developed that offers advantages over the state of the art in terms of package, weight, stiffness and crash performance. To develop the new shock tower, connection points and package spaces in the periphery of the Honda Accord MY 2011 were analysed and defined. Based on quasi-static misuse load cases and topology optimization, it was possible to develop a load-compliant rib structure for the hybrid-cast shock tower reinforced by steel in the dome area. A so-called tension band for the IIHS small overlap crashworthiness evaluation test (SOL) was also integrated into the new shock tower to ensure homogeneous load distribution. The new shock tower was tested virtually in comparison with the reference steel shock tower and an Al-cast shock tower in quasi-static and dynamic crash load cases. In the quasi-static test, the hybrid-cast shock tower showed significantly increased stiffness. In the dynamic load cases, a significant overall homogenization of force distribution on the existing load paths in die front body structure was achieved. In addition, 5 mm package space for spring and damper could be gained for better driving behaviours of the car.

The objective in the development of passive vehicle safety systems is to protect the occupants in case of an accident. The severity of injuries experienced by the occupants are, among other factors, evaluated based on sensor signals from instrumented dummies in crash tests. Dummy signals, the so-called occupant loads, highly depend on the properties of vehicle structure and restraint systems. These properties need to be defined in very early stages of the development process. To support the engineers in their decision process, different metrics are used to evaluate the vehicle deceleration, the so-called crash pulse. These metrics do not consider the influences of vehicle-specific restraint system properties and can therefore only be used for pulse characterization. They are not suitable to make statements about the expected occupant loads in a crash test. For an efficient design of the passive safety systems, it is important to gain insights on the interaction between vehicle structure and restraint system properties in early stages of the development process. To predict occupant loads based on information, which is available in these early phases, a new method, the Real Occupant Load Criterion for Prediction (ROLC(_p)), is presented. By considering the vehicle pulse and specific restraint system properties in its calculation, the ROLC(_p) shows good correlation with the dummy’s maximum chest acceleration. As the ROLC(_p) can be used in early design phases, it represents a useful tool to improve the current vehicle safety development process.

The aim of the study is to investigate the most effective approach to reduce the emissions of a SI-engine while using a limited amount of renewable fuel. In this study, the renewable fuels ethanol, methanol, 2-ethoxy-2-methylpropane (ETBE), acetone, and dimethylformamide (DMF) were investigated with various fixed admixture rates and with a fully variable on-board fuel mixture (Smart-Fuel concept). One result of the study is that for a Smart-Fuel concept using methanol a reduction in CO₂ emissions of approx. 12.5% and a reduction in particulate emissions of approx. 60% can be achieved, when considering an entire car fleet. In terms of engine efficiency, as well as particulate emissions, the pure substances, except DMF, achieved significant improvements compared to standard gasoline. Compared with the pure substances, the Smart-Fuel concept achieved lower advantages; however, it used significantly less scarcely available renewable fuel in the process. Based on the limited availability of renewable fuels within the first stages of a circular economy, the Smart-Fuel concept proves to be a very efficient transition technology to achieve the CO₂ reduction targets. The Smart-Fuel concept only uses renewable fuel when it is worthwhile in terms of efficiency or emissions. Predefined fuel blends in a mono-fuel concept offer much less reduction potential in terms of emissions than the Smart-Fuel concept. However, with respect to particulate raw emissions, especially for moderate mixing rates significantly increased particle emissions are sometimes observed, despite the overall very good performance of the pure substances.

In this paper, the approach for a functionally integrated battery housing is presented, to avoid structural redundancies towards the vehicle body. The goal is to reduce the overall structural weight while simultaneously increasing the package space for battery modules. The typically existing boundary conditions for the battery system are taken into account. Especially, the detachability of the battery as a closed unit is in focus, to ensure the leak tightness of this system and to enable replacement. Based on the available space in a research vehicle, such a functionally integrated concept is developed. In particular, the vehicle floor and the vehicle rocker are identified as suitable components for integration. The verification of the concept with regard to the crash performance is carried out on component and on full vehicle level. On both levels, the side pole impact is used as load case and the deformation behavior is investigated.

In the vehicle development process, the availability of vehicle models is of essential importance for design and validation of the driving characteristics. These vehicle models, which have to fulfill the requirements of the specific application in terms of complexity and level of detail, can be obtained using a multitude of established processes. These include, for example, the derivation of real-time capable models from MBS models, the measurement of subsystems on specialized test benches, but also the characterization of the overall vehicle behavior based on road measurements. IFS and FKFS operate a Handling Roadway whose primary field of applications is the examination of overall vehicle dynamics under laboratory conditions. However, the institutes also pursue the goal of expanding the range of applications to include the parametrization of complete vehicle models and their subsystems. To analyze the potentials of such a method, measurements are conducted which are used to identify fundamental vehicle characteristics. For this purpose, the sensors already available as part of the test system are complemented by wheel force transducers and wheel vector sensors. The measurements are used to parametrize the tire, K&C, steering, and spring parameters of a vehicle model for lateral dynamics tests. Simulations of dynamic driving maneuvers show a good comparability with equivalent dynamic tests performed on the test system.