Automotive and Engine Technology最新文献

The focus of this paper is on the verification and validation of computational approaches commonly used for the simulation of in-cylinder processes involving intense turbulent flow and combustion. Furthermore, the tumble behavior during the intake stroke at different engine operating points is investigated since the cycle-to-cycle variability of the subsequent tumble breakdown at the end of compression stroke is reported to negatively affect the engine efficiency. In this respect, measurements with advanced laser diagnostics-based experimental techniques (TR-PIV) in an optically accessible engine have been performed and compared with LES for flow in the same engine, under identical operating conditions. The study focused on the intake stroke under wide open throttle conditions and engine speed of 1000 RPM and 1500 RPM. The ensemble averaged velocity fields of the two methods were analyzed and compared. A counter-clockwise motion and some secondary recirculation zones were identified and quantified in both methods. The same trend for tumble ratio was observed between experiments and simulations and a good agreement was found for most CAD especially at 1500 RPM. At 1000 RPM comparison showed significant variations, which after a detailed analysis of the instantaneous fields, are attributed to the strong cycle-to-cycle variability of the instantaneous tumble center. It is observed, that for relevance index values below 0.75 the ensemble averaged flow fields that the two methods predict significantly differ.

This paper deals with the impact of heating on the driving range of battery electric vehicles (BEVs), as the energy from a car battery is used on both driving and heating of the car. The possible solution is the novel heating device with its own energy source—a low-pressure thermal energy storage. The use of an inner heat exchanger in this thermal energy storage makes the design of the whole heating device very simple and with the division of a high-pressure from a low-pressure part increases its safety. By adding some salts into water, it is possible to decrease the value of inner pressure (vapour pressure) in the thermal storage and to increase its storage capacity along with the conservation of good thermodynamic properties of the storage medium. In the conclusion, the measurement results of the heating device tested under real conditions are presented.

Urban traffic is a significant contributor of particulate matter to the environment (Kessinger et al. in https://www.umweltbundesamt.de/sites/default/files/medien/5750/publikationen/hgp_luftqualitaet_2020_bf.pdf, 2021). Hence, there is a high interest in the measured data of roadside immission measurement station. In the federal state Saxony (Germany), the State Office for Environment, Agriculture and Geology (LfULG) is responsible for supervision of the air pollution. In a joint project, the LfULG, the Leibniz Institute for Tropospheric Research (TROPOS) and the Chair of Combustion Engines and Powertrain Systems of the Technical University of Dresden (Lehrstuhl für Verbrennungsmotoren und Antriebssysteme, LVAS) measured the particulate immission* from a selection of passenger cars in an “environment simulation” Weinhold et al. (https://publikationen.sachsen.de/bdb/artikel/36768q, 2020). Especially direct injection spark ignition engines, DISI, without particle filter have a high particulate matter emission, depending on the operating condition. However, an increase of the particulate matter immission due to the rising market penetration of DISI engines was not measurable at the immission measurement stations of LfULG. To investigate the effect of vehicle exhaust emission and immission, an experiment was developed to measure particulate matter immission similar to road conditions on a chassis dynamometer. Five used cars with different engines, exhaust after treatment systems and mileage were evaluated regarding their emissions and particulate immissions. Unexpectedly, a high amount of ultrafine particulate matter smaller 100 nm was found during the emission measurements, although the exhaust emissions were completely extracted to the CVS measurement system. It was concluded that these particles were assignable to break and tire wear. This paper summarizes the most important findings, the complete report is available in Weinhold et al. (https://publikationen.sachsen.de/bdb/artikel/36768q, 2020).

In this paper, we describe experimental developments in an Exhaust Aftertreatment System (EAS) used in a four-cylinder Compression Ignition (CI) engine. To meet the carbon dioxide (CO(_mathrm {2})) fleet limit values and to demonstrate a clean emission concept, the CI engine needs to be further developed in a hybridized, modern form before it can be included in the future fleet. In this work, the existing EAS was replaced by an Electrically Heated Catalyst (EHC) and a Selective Catalytic Reduction (SCR) double-dosing system. We focused specifically on calibrating the heating modes in tandem with the electric exhaust heating, which enabled us to develop an ultra-fast light-off concept. The paper first outlines the development steps, which were subsequently validated using the Worldwide harmonized Light-duty vehicles Test Cycle (WLTC). Then, based on the defined calibration, a sensitivity analysis was conducted by performing various dynamic driving cycles. In particular, we identified emission species that may be limited in the future, such as laughing gas (N(_mathrm {2})O), ammonia (NH(_mathrm {3})), or formaldehyde (HCHO), and examined the effects of a general, additional decrease in the limit values, which may occur in the near future. This advanced emission concept can be applied when considering overall internal engine and external exhaust system measures. In our study, we demonstrate impressively low tailpipe (TP) emissions, but also clarify the system limits and the necessary framework conditions that ensure the applicability of this drivetrain concept in this sector.

The light-induced fluorescence (LIF) represents an important tool for the continuous improvement and further development of combustion engine systems regarding efficiency increase. In this work, the interactions between light-emitting diode (LED) and laser diode light radiation, engine oil/fuel and three fluorescence tracers are investigated on an application-related investigation system for the design of qualitative LIF experiments. Thereby two efficient light sources for engine combustion chamber lighting are presented. For different engine oil/fuel tracer combinations, the fluorescence is examined in its intensity and its spectrum depending on the temperature, concentration and temperature history. With oil temperature variations of up to 150 °C, changes in the fluorescence spectrum and fluorescence intensities that decrease by up to 80% are evident. For specific tracer oil/fuel mixtures, concentration-dependent maximum intensities and different temperature history behaviors can be revealed. The results shown support the design of spectral engine examination setups and give tracer dosage recommendations. Additionally, an engine LIF setup for in-cylinder tracking of engine operating media is presented.

When buying a car, the acoustic impression of quality of a vehicle drive train is becoming more and more relevant. The perceived sound quality of the engine unit plays a key role here. Due to the nature of individual background noises, that sound quality is negatively influenced. These noise components, which are perceived as unpleasant, need to be further reduced in the course of vehicle development with the identification and evaluation of disruptive noise components in the overall engine noise being a prerequisite for effective acoustics optimization. In particular, the pulsed ticker noise is classified as particularly annoying in Otto DI engines, which is why this article aims to analyze and evaluate the ticking noise components from the overall noise. For this purpose, an empirical formula was developed which can classify the ticking noise components in terms of their intensity. This is purely perception-based and consists of the impulsiveness, the loudness and the sharpness of the overall engine noise. As with other psychoacoustic evaluation scales, the rating was made from 1 (very ticking) to 10 (not ticking). The ticker noise evaluation formula was then verified on the basis of hearing tests with the help of a jury of experts. According to this, it can be predicted precisely in which engine map areas the ticker noise undermines the pleasantness of the overall engine noise.

This paper deals with the emission optimization of a compression ignition (CI) engine during cold ambient operation. Hence, in the present study, the effect of different injector nozzle geometries and pilot injection strategies, but also the influence of intake swirl, rail pressure, exhaust gas recirculation (EGR) as well as EGR cooling on the emission behavior during cold run are investigated. Therefore, test bed experiments under steady-state cold conditions are conducted on a state-of-the-art CI single cylinder research engine (SCRE) with approximately 0.5 l swept volume representing the typical passenger car (PC) cylinder size. The cold charge air temperature of down to −8 (^{circ }hbox { C}) and a low engine coolant and lube oil temperature represent a cold run close to reality. For emulating the higher friction of a typical 4-cylinder PC engine during cold run, the indicated mean effective pressure (IMEP) is increased according to a specifically developed equation and the turbocharger main equation is solved permanently to adjust the gas exchange loss. To take account of a potential future tightening of emission legislation, in addition to limited exhaust gas emissions, non-limited emissions such as carbonyls are measured as well. Since alternative fuels are able to make a significant contribution to the defossilisation of transportation, an oxygen-containing fuel, consisting of 100 % renewable blend components (HVO, ethers and alcohols) and fulfilling the EN 590 legislation is investigated under the same cold conditions in addition to the research on conventional diesel fuel.

Due to a large number of degrees of freedom and connected powertrain functionalities, the development of operating strategies for plug-in hybrid electric vehicles is an especially complex task. Besides optimizations of drivability, noise, vibrations and harshness as well as energy efficiency, the main challenge lies in ensuring emissions conformity. For this purpose, test vehicles are typically applied to achieve a realistic test and validation environment. However, operating strategy calibration using test vehicles has the drawbacks, that (i) it is very time consuming and cost intensive, (ii) it can only be conducted in late development phases and (iii) cannot be applied to reproducing driving loads for a valid comparison. To overcome these issues, this paper presents a consistent engine-in-the-loop approach combining real engine hardware and multiple software elements to represent PHEV behavior at the engine test bench. Thereby, an environment is created, which allows for realistic, flexible, cost efficient and reproducible testing. The effectiveness of the presented framework is evaluated by comparing relevant on-road measurements with their reproduction at the engine test bench. The results show that the vehicle on-road behavior can be replicated using the described testing environment. Particularly engine start/stop behavior and load levels—the core functionalities for operating strategy calibration—are matched. The proven level of realism in powertrain behavior enables further use cases beyond on-road measurement reproduction, i.e. varying individual component properties and observing real-world consequences at the test bench without the need for vehicle tests.

This paper focuses on the battery aging of automotive high power lithium-ion batteries intended for 48 V mild hybrid systems. Due to a long vehicle lifetime, battery aging is of high importance, and its consideration within a hybrid system is crucial to ensure a sufficient lifetime for the battery. At the moment, only a few aging investigations and models specifically for automotive high power cells are available. Consequently, all present aging consideration methods are based on the few published aging models focusing on consumer cells. This paper describes the development of an aging model for automotive high power cells and the integration into a mild hybrid operating strategy to actively control the battery aging process during its operation. The underlying aging investigations of high-power battery cells are shown to analyze the main influences of temperature, state of charge, and C-rate. These tests are used to develop the aging model, capable of considering the main influences on the aging process. Based on this model and all gained insights, different methods for considering battery aging in a mild hybrid system are investigated. The goal is to control the aging process during operation and consequently decrease the negative influence. Two active intervention methods are developed and integrated into a 48 V mild hybrid operating strategy to validate their potential. It is possible to control the aging process and at the same time to use the insights for improving the basic hybrid powertrain design regarding reduced aging and battery costs.