Automotive and Engine Technology最新文献

Hybrid vehicles, with their combined use of internal combustion engines and electric motors, present a unique opportunity to leverage intelligent control strategies for optimal performance. The method presented in this paper aims to improve the efficiency of a hybrid powertrain through an increased usage of the advantages of the electric components. While conventional hybrid operation strategies must determine the torque-split on either rule-based decision logics or on strategies that are optimized for certain test scenarios a predictive strategy can optimize the torque-split under consideration of the upcoming load requirements. Therefore, this paper explores the development and implementation of real-time predictive driving and operating strategies for hybrid vehicles to enhance fuel efficiency and reduce environmental impact. The data pertaining to road networks and traffic conditions, currently accessible from numerous map providers, can be effectively utilized to further amplify the benefits offered by hybrid vehicles. This information will be used to improve the accuracy of the predicted driving situations, which in turn improves the effectiveness of the predictive hybrid strategy by increasing the accuracy of the predicted load requirements. Advancements in prediction model accuracy have been shown to enhance the effectiveness of predictive hybrid control strategies, leading to higher energy efficiency and lower emissions. The present study develops and evaluates enhanced prediction models and a real-time predictive energy management strategy in simulation and Hardware-in-the-Loop (HiL) testing. We position the contribution at the system level, integrating forecasting, horizon supervision, receding-horizon P-ECMS with on-horizon EF adaptation and a state-change cost, and ΔSOC-fair evaluation under HiL-level timing. For a representative urban/rural route, the enhanced predictive strategy achieves a ΔSOC-fair, fuel-equivalent reduction of up to 12.18%, approaching the 14.4% obtained under perfect prediction, while reducing engine state transitions from 110 to 30, thereby improving both efficiency and driving comfort. This study is framed as a potential analysis: in this recuperation-rich case the strategy delivers high reduction potential, whereas on a Real Driving Emissions (RDE) trip with limited recuperation opportunity the improvement is ≈ 1% even under perfect prediction, indicating route-dependent potential rather than route-agnostic savings.

Hydrogen direct-injection engines offer a promising pathway for decarbonizing heavy-duty transportation, but accurate prediction of mixture formation and NO(_x) emissions remains challenging due to complex injector dynamics and strong cycle-to-cycle variability. This work presents a comprehensive computational and experimental investigation of supersonic H(_2) direct injection, mixing, combustion, and NO formation in a single-cylinder heavy-duty hydrogen engine operated at 1100 rpm and (lambda ) = 2.6. A detailed three-dimensional CFD model is developed, coupling a pressure-based injection boundary condition with a realistic Bosch F2 prototype injector needle-lift profile to capture valve-bounce effects. The model is validated against measured in-cylinder pressure, fuel and air mass, and NO emission data. Multi-cycle combustion behavior and NO emission variability are analyzed using the concurrent perturbation method (CPM), with 20 statistically independent realizations at reduced computational cost. Results show that near-spark mixtures with higher fuel concentration accelerate flame propagation and increase peak NO by a factor of two (76 ppm vs. 32 ppm). Simulations reveal that NO forms predominantly in local pockets of high fuel concentration, with turbulent flame speeds of 11–22 m/s during the early combustion phase. Predicted exhaust-port NO levels agree qualitatively with experiments, though unsteady RANS tends to overpredict NO due to limited small-scale mixing. The study demonstrates that resolving the injector flow rather than approximating boundary conditions, combined with CPM can effectively capture hydrogen combustion dynamics and emission variability.

The optimal integration of redundant actuators in an overactuated vehicle may be found by considering energy efficiency in the actuator allocation strategy. This paper investigates the potential to reduce the drive power demand of an electric vehicle with wheel individual drive through optimal allocation of drive torques and steering angles at the front and rear wheels. The actuator allocation problem is considered for the entire feasible normal and tangential acceleration range of the vehicle. The influences of electrical power losses of the motor-inverter system and tyre slip power losses on power demand are examined. By just considering the tyre slip power losses, the optimal control allocation reduces the drive power demand up to 20%, with the most significant reduction in the region of medium to high normal and tangential accelerations. The potential power reduction with respect to suboptimal strategies is validated in simulation and experimental tests by implementing the optimal torque distribution strategy as a feed-forward control on a demonstrator vehicle. The theoretically found power reduction gains are experimentally validated.

This paper addresses the thermal management of batteries during fast charging of electric vehicles. Using comprehensive measurement data from a state-of-the-art battery electric vehicle (BEV), a control-oriented model of the battery and its thermal system is developed and parameterized. The existing thermal management strategy for fast charging is first analyzed, after which a predictive strategy specifically for this use case is proposed. The approach consists of two steps: offline setpoint optimization via dynamic programming and optimal control allocation using nonlinear model predictive control (NMPC). The strategy’s performance is evaluated using a validated high-fidelity simulation model. Compared to the existing state-of-the-art strategy, the proposed predictive approach reduces energy consumption by up to 0.41  kWh at moderate ambient temperatures through efficient cooling, and shortens charging time by up to 4.5% at low ambient temperatures through aggressive heating.

The present work investigates the spark ignition and flame kernel formation processes in hydrogen–air mixtures under real engine-relevant conditions from a chemical-physical perspective. A one-dimensional numerical model based on the INSFLA solver with cylindrical geometry is used to resolve the coupled effects of detailed chemical kinetics and molecular transport during the ignition phase. The initial and boundary conditions (e.g. initial pressure, initial temperature, equivalence ratio, spark width and duration) are directly taken from a hydrogen-fueled internal combustion engine (H2-ICE) operation point. The simulations capture both failed and successful spark ignition events. Sensitivity analyses identify chain-branching and chain-termination reactions as the dominant chemical kinetic factors controlling the speed of flame kernel formation, while molecular transport effects become significant only after the onset of flame propagation. Furthermore, the evolution of NO emissions is analyzed in detail, showing that thermal NO dominates at high temperatures, whereas the NNH pathway contributes substantially during the early ignition stage, with the (text {N}_2)O route playing a minor role. Overall, the study provides mechanistic insights into the chemical and transport processes governing early flame development and NO formation in hydrogen-fueled engines, offering a scientific foundation for optimizing spark ignition strategies and reducing NOx emissions under realistic engine conditions.

The global push for defossilization necessitates the advancement of hydrogen internal combustion engines as a key solution for the heavy-duty transport sector. However, the distinct combustion properties of hydrogen, particularly its high reactivity, introduce operational challenges for port-fuel-injected (PFI) engines, most critically the risk of backfire—the uncontrolled ignition in the intake system. This phenomenon not only makes the engine potentially unsafe for operation but also severely limits the achievable power density and combustion stability. Addressing this barrier requires a comprehensive understanding of the complex interactions between various engine control parameters. This study presents a coordinated experimental and computational fluid dynamics (CFD) investigation focusing on strategies to mitigate backfire in a single-cylinder, heavy-duty hydrogen PFI engine. The influence of engine parameters such as injector location, start of injection (SOI) timing, backpressure, engine valve timing and injection pressure and duration on mixture formation, and backfire onset were also analyzed. The findings establish critical guidelines for defining the stable operating window, demonstrating how the tuning of key control variables can effectively promote mixture preparation, reduce backfire instances and potentially increase engine efficiency. This research provides an essential framework for the reliable, safe and efficient deployment of hydrogen PFI technology in future low-carbon transportation applications.

Hydrogen internal combustion engines have the potential to become a key zero-emission propulsion system of the future. Especially the use in heavy-duty applications seems promising. However, some challenges remain, one of them being the tendency of these engines towards combustion anomalies. The present paper proposes a methodology for the quantification and evaluation of combustion anomalies occurring under varying operating conditions on an engine test bench. For this, a test procedure is defined to detect irregularities in a systematic way. The classification of the anomalies is conducted through a post-processing routine, which utilizes appropriate parameter limit values. The findings of this study indicate that engine anomaly behavior is strongly influenced by ambient conditions, most notably by elevated charge air and coolant temperatures. Furthermore, ignition timing exerts a significant additional effect. This paper also addresses the reproducibility and validity of the test procedure for real-life operation. All research activities conducted in this paper were performed under the scope of the COMET project Hylley.

Hydrogen presents a promising opportunity for the reduction of CO₂ emissions in combustion processes. Due to its wide ignition limits, operation in lean mode is possible, which significantly reduces NO_x emissions. However, this lean operation also leads to a reduction in the resulting torque. In contrast, stoichiometric operation increases maximum power output but leads to increased NO_x emissions. In particular, a cost-effective three-way catalyst can be used in stoichiometric operation, enabling effective emission control. This investigation proposes an innovative approach that involves lean-burn operation at part load conditions and switching to stoichiometric operation at full load. The transition between these two modes has a considerable impact on overall NO_x emissions. To optimize this process, new functions were developed that implement countermeasures such as lambda control, ignition timing adjustment, catalyst purging, and shortening the switching range through the use of variable valve timing and variable turbine geometry. The results show that nitrogen oxide (NO_x) emissions downstream of the three-way catalyst are kept below ({text{c}}_{{{text{NO}}_{x} }} = 100,{text{ppm}}) in the lean operating range and below ({text{c}}_{{{text{NO}}_{x} }} = 30;{text{ppm}}) in the stoichiometric operating range. By optimizing the transition between the two operating modes and using advanced emission control technologies, it is possible to reduce NO_x emissions by 84% while maintaining power efficiency under different load conditions. In addition, the almost torque-neutral switching between the two operational modes ensures that the vehicle’s drivability is not impaired. By incorporating additional dosing of a urea-water solution in an active SCR system, a significant improvment in NO_x reduction is attained, achieving levels comparable to those of diesel internal combustion engines. This dual-mode operation strategy improves the feasibility of hydrogen as a viable fuel alternative in future energy systems.

Hydrogen fuelled internal combustion engines (H₂-ICEs) are a promising zero-carbon propulsion solution. Although their steady-state performance has been investigated widely, sufficient transient performance is still challenging, especially for lean-burn, turbocharged configurations. This paper presents an experimental investigation into the transient behaviour and identifies key parameters for engine response and emission behaviour of a lean-burn turbocharged H₂-ICE. The engine control unit features dedicated strategies for transient operation: an acceleration enrichment function that temporarily allows a richer (lambda) hence more fuel mass to improve engine response and an ignition retard function to mitigate combustion anomalies. Both functions are activated based on the difference between requested and calculated actual torque. These functions were the enabler to create calibrations with different transient performance. Besides known Non-Road Transient Cycle and World Harmonized Transient Cycle the transient performance was evaluated using a custom test cycle consisting of load steps at various engine speeds. The engine response time from the beginning of the load step until 70% of the full load torque was reached—the t_70%—was used as a key metric. The results highlight the trade-off between fast torque response and emission control and demonstrate the importance of transient engine control. Especially the difference to diesel transient performance shows the need for further development. All tests were conducted within the COMET Research Project Hylley.

The thermal management system and the balance-of-plant (BoP) in fuel cell electric vehicles (FCEV) are characterized by a particularly high level of complexity and a number of interfaces. Optimizing the efficiency of the overall vehicle is of special importance to maximize the range and increase the attractiveness of this technology to customers. This paper focuses on the optimization potential of the air supply system in the BoP, whereby the charging concepts of the electric supercharger (ESC) and the electrically assisted turbocharger (EAT) as well as the integration of water spray injection (WSI) at the compressor inlet are investigated in the framework of an FCEV complete vehicle co-simulation. As a benchmark for the integration of these optimization measures, the complete vehicle co-simulation is designed for a fuel cell electric passenger car of the current generation. Here, thermo-hydraulic fluid circuits in the thermal management software KULI are coupled with mathematical-physical models in MATLAB/Simulink. Applying advanced simulation methodologies for the components of fuel cell, powertrain and vehicle cabin enables the mapping of the effects of realistic operating conditions on the FCEV characteristics. The EAT offers the advantage over the ESC that, due to the arrangement of an exhaust gas turbine, a part of the exhaust gas enthalpy flow downstream of the fuel cell stack can be recovered, which reduces the electrical compressor drive power. Moreover, an additional reduction of this power consumption can be achieved by WSI, as the effect of evaporative cooling lowers the initial compression temperature. For analysis and comparison, these concepts are again modeled with high degree of detail and integrated into the benchmark overall vehicle simulation. The results indicate considerable reductions in the electric compressor drive power of the EAT compared to the ESC, with noteworthy potential for reducing the vehicle’s hydrogen consumption. At an operating point in Worldwide harmonized Light Duty Test Cycle (WLTC) under 35 (^{circ })C ambient temperature and 25 % relative humidity, the electrical compressor drive power shows a reduction potential of −40 %, which corresponds to a vehicle-level hydrogen consumption reduction of up to −3 %. In addition, the results also highlight the effect of the WSI in both charging concepts, whereby its potential to reduce the hydrogen consumption on the overall vehicle level is relatively small. In WLTC, at 35 (^{circ })C ambient temperature and 25 % relative humidity, the compressor drive power reduction potential for ESC and EAT averages −5 %, while the effect on hydrogen consumption is only around −0.25 %.