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Technical Paper

NVH Aspects of Electric Drive Unit Development and Vehicle Integration

2019-06-05
2019-01-1454
The automotive industry continues to develop new powertrain and vehicle technologies aimed at reducing overall vehicle-level fuel consumption. Specifically, the use of electrified propulsion systems is expected to play an increasingly important role in helping OEM’s meet fleet CO2 reduction targets for 2025 and beyond. This will also include a strong growth in the demand for electric drive units (EDU). The change from conventional vehicles to vehicles propelled by EDU leads to a reduction in overall vehicle exterior and interior noise levels, especially during low-speed vehicle operation. Despite the overall noise levels being low, the NVH behavior of such vehicles can be objectionable due to the presence of tonal noise coming from electric machines and geartrain components. In order to ensure customer acceptance of electrically propelled vehicles, it is imperative that these NVH challenges are understood and solved
Technical Paper

The research on throttle influence on aerodynamic noise of gasoline engine intake system

2019-06-05
2019-01-1485
Throttle, as a significant component for the engine, could play a central role on the control of the intake flow, and would influence the fuel consumption, emission and dynamic performance of the internal combustion engine. Fluctuating the air flow and generating the aerodynamic noise, the opening and closing of the throttle valve would largely increase the intake noise. In this research, the aerodynamic noise of the intake system under steady working conditions of the engine is calculated by the co-simulation of GT-Power, Fluent and LMS Virtual.Lab. With the coupled simulation between the two programs, GT-Power and Fluent, it could simulate the gas flow inside the engine intake system, under the actual running condition of engine. The velocity at the boundary of the intake system was used as the boundary condition for CFD calculation. The LES turbulence model with a prism layer of 0.01mm thickness was applied in the flow analysis.
Technical Paper

On the Measurement and Simulation of Flow-Acoustic Sound Propagation in Turbochargers

2019-06-05
2019-01-1488
Internal combustion engines are increasingly being equipped with turbochargers to increase performance and reduce fuel consumption and emissions. Being part of exhaust and intake systems, the turbocharger strongly influences the orifice noise emission. Although 1D-CFD simulations are commonly used for the development of intake and exhaust systems, validated acoustic turbocharger models are not yet state-of-the-art. Consequently, the first aim of the paper is the investigation of the influence on the orifice noise and the development of an accurate 1D-CFD model. Firstly, active and passive acoustics of turbochargers are distinguished. Complex active turbocharger noise emissions were investigated on a turbocharger test rig and could be correlated with unstable rotating stall. Therefore critical acoustic operation can be identified in early engine development stages by comparison to other tested turbochargers.
Technical Paper

Modelling of a Discrete Variable Compression Ratio (VCR) System for Fuel Consumption Evaluation - Part 2: Modelling Results

2019-04-02
2019-01-0472
Variable Compression Ratio systems are an increasingly attractive solution for car manufacturers in order to reduce vehicle fuel consumption. By having the capability to operate with a range of compression ratios, engine efficiency can be significantly increased by operating with a high compression ratio at low loads, where the engine is normally not knock-limited, and with a low compression ratio at high load, where the engine is more prone to knock. In this way, engine efficiency can be maximized without sacrificing performance. This study aims to analyze how the effectiveness of a VCR system is affected by various powertrain and vehicle parameters. By using a Matlab model of a VCR system developed in Part 1 of this work, the influence of the vehicle characteristics, the drive cycle, and of the number of stages used in the VCR system was studied.
Technical Paper

Combined Technologies for Efficiency Improvement on a 1.0 L Turbocharged GDI Engine

2019-04-02
2019-01-0233
Cooperated with a local Chinese brand, Geely, the goal of this research is to improve the thermal efficiency on an extremely downsized 3-cylinder 1.0 L turbocharged GDI engine. Effects of compression ratio, low pressure cooled EGR, valve timing and viscosity of oil on fuel economy were studied. The results show that increasing compression ratio (from 9.6 to 12) can improve fuel economy at relative low load (below 12 bar BMEP), but has negative effect at high load due to increased knock intensity. EGR can significantly reduce the pumping loss at low load, optimize combustion phase and reduce exhaust gas temperature. Therefore, the fuel consumption is decreased at all test points. The average brake thermal efficiency (BTE) benefit percentage is 3.47% with 9.6 compression ratio and 5.33 % with 12 compression ratio. However, at higher load (over 18bar BMEP), EGR needs to be reduced to reach the target load, which would affect its beneficial to efficiency.
Technical Paper

Thermal Management of a Hybrid Vehicle Using a Heat Pump

2019-04-02
2019-01-0502
This paper presents the thermal management of a hybrid vehicle (HV) by using a heat pump system in cold weather. The advantage of an HV is a high efficiency of the vehicle system since an electric motor and an engine are coupled and optimally controlled. However, in the conventional HV, we see the fuel economy degradation in cold weather because delivering heat to the passenger cabin by using an engine results in a low efficiency of the vehicle system. To improve the fuel economy degradation, in this study, a heat pump is used and combined with an engine for the thermal management. The heat pump with an electrically driven compressor pumps heat from ambient into a water-cooled condenser. The heat which is generated by the engine and the heat pump is delivered to the engine and the passenger cabin because the engine needs to warm up quickly to reduce the emission and the cabin needs heat for thermal comfort.
Technical Paper

Thermal analysis of steel and aluminium pistons in a light duty diesel engine

2019-04-02
2019-01-0546
Chromium-molybdenum alloy steel pistons, which have been used in commercial vehicle applications for some time, have more recently been proposed as a means of improving thermal efficiency in light-duty applications. This work reports a comparison of the effects of geometrically similar aluminium and steel pistons on the combustion characteristics and energy flows on a single cylinder high-speed direct injection diesel research engine tested at two speed / load conditions (1500 rpm / 6.9 bar nIMEP and 2000 rpm / 25.8 bar nIMEP) both with and without EGR. The results indicate that changing to an alloy steel piston can provide a significant benefit in brake thermal efficiency at part-load and a reduced (but non-negligible) benefit at the high-load condition and also a reduction in fuel consumption. These benefits were attributed primarily to a reduction in friction losses.  
Technical Paper

Numerical study of Intake Manifold Water Injection on Performance and Emissions in a Heavy-duty Nature Gas Engine

2019-04-02
2019-01-0562
The performance of heavy-duty nature gas engines has been limited by combustion temperature and NOx emissions for a long time. Recently, water injection technology has been widely considered as a technical solution in reducing fuel consumption and emissions simultaneously in both diesel and gasoline engines. This paper focuses on the impacts of intake manifold water injection on characteristics of combustion and emissions in a heavy-duty nature gas engine through numerical methods. A detailed numerical model was established and validated with experimental data of pressure traces in CFD software coupled with detailed chemical kinetics. The simulation was mainly carried out under low speed and full load condition, and knock level was also measured and calculated by Logarithmic Knock Intensity (LKI). The results show that intake manifold water injection is an efficient way to reduce high NOX emissions in nature gas engines without deteriorating other emissions characteristics.
Technical Paper

Effect of Diamond-Like Carbon Coating on Anti-Scuffing Characteristics of Piston Pins

2019-04-02
2019-01-0184
It has been proposed that downspeeding combined with high boost levels would effectively reduce fuel consumption in heavy-duty diesel engines. Under low-speed and high-boost operating conditions, however, the in-cylinder gas pressure, which acts on the piston crown, is greater than the piston inertia force (such that there is no force reversal), over the entire range of crank angles. Therefore, the piston pin never lifts away from the main loading area (the bottom) of the connecting rod small-end bushing where the contact pressure against the piston pin is highest. In such operating conditions, lubricant starvation is easily induced at the interface between the piston pin and small-end bushing. Through carefully devised engine tests, the authors confirmed that the piston pin scuffing phenomenon arises when the boost pressure exceeds a critical value at which the no-force reversal condition appears.
Technical Paper

Optimized Driving Cycle Oriented Control for a Highly Turbocharged Gas Engine

2019-04-02
2019-01-0193
The article is focused on a 1-D drive dynamic simulation of a highly turbocharged gas engine. A mono fuel CNG engine has been developed as a downsized replacement of the diesel engine for a medium size van. The basic engine parameters optimization is provided in a steady state operation and a control adjustment is applied to a dynamic vehicle model for a transient response improvement in highly dynamic operation modes of the WLTC (world light duty test cycle), selected for investigation. Vehicle simulation model with optimized control system is used for driving cycle fuel consumption and CO2 emissions predictions compared with the basic engine settings.
Technical Paper

Validation of Control-Oriented Heavy Duty Diesel Engine Models for Non-Standard Ambient Conditions

2019-04-02
2019-01-0196
Complying to both the increasingly stringent pollutant emissions as well as (future) GHG emission legislation - with increased focus on in-use real-world emissions - puts a great challenge to the engine/aftertreatment control development process. Control system complexity, calibration and validation effort has increased dramatically over the past decade. A trend that is likely to continue considering the next steps in emission and GHG emission legislation. Control-oriented engine models are valuable tools for efficient development of engine monitoring and control systems. Furthermore, these (predictive) engine models are more and more used as part of control algorithms to ensure legislation compliant and optimized performance over the system lifetime. For these engine models, it is essential that simulation and prediction of system variables during non-nominal engine operation, such as non-standard ambient conditions, is well captured.
Technical Paper

Dual Mode VCS Variable Compression System - System Integration and Vehicle Requirements

2019-04-02
2019-01-0248
Future legislation scenarios as well as stringent CO2 targets, in particular under real driving conditions, will require the introduction of new and additional powertrain technologies. Beside the increasing electrification of the powertrain, it will be essential to utilize the full potential of the Internal Combustion Engine (ICE). There is clearly a competition of new and different ICE-Technologies [1] including VCR. VCR systems are expected to be introduced to a considerable number of next generation turbocharged Spark Ignited (SI) engines in certain vehicle classes. The implementation of Miller or Atkinson cycles is an essential criterion for increased geometric Compression Ratio (CR). The DUAL MODE Variable Compression System (VCS)TM enables a 2-stage variation of the connecting rod length and thus of the compression ratio (CR).
Technical Paper

Particle Reduction in LPG Lean Stratified Combustion by Intake Strategies

2019-04-02
2019-01-0253
Lean stratified combustion shows high potential to reduce fuel consumption because it operates without the intervention of a throttle valve. Despite its high fuel economy potential, it emits large amounts of particulate matter (PM) because the locally rich mixture is formed at the periphery of a spark plug. Furthermore, the combustion phasing angle is not realized at MBT ignition timing, which can bring high work conversion efficiency. Since PM emission and work conversion efficiency are in a trade-off relation, this research focused on reducing PM emission through achieving high work conversion efficiency. Two intake air control strategies were examined in this research; throttle operation and late intake valve closing (LIVC). The experiment was conducted in a single cylinder spray-guided direct injection spark ignition (SG-DISI) engine with liquefied petroleum gas (LPG). The injected fuel amount was fixed so as to investigate the effect of each strategy.
Technical Paper

Effects of the Ambient Conditions on the Spray Structure and Evaporation of the ECN Spray G

2019-04-02
2019-01-0283
The use of Gasoline Direct Injection (GDI) continuously increases due to the growing demand of efficiency and power output for i.c. engines. The optimization of the fuel injection process is essential to prepare an air-fuel mixture capable to promote efficient combustion, reduced fuel consumption and pollutant emissions. Good spray atomization facilitates fuel evaporation in i.c. engines thus contributing to the fuel economy and lowering the emissions. One of the key features of a multi-hole injector is to provide an optimal spray pattern in the combustion chamber and a good mixture homogenization considering the engine-specific characteristics such fuel mass-flow rate, cylinder geometry, injector position, and charge motion. This work aims to investigate the injection processes of an eight-hole direct-injection gasoline injector from the Engine Combustion Network (ECN) effort on gasoline sprays (Spray G, serial #19).
Technical Paper

Validation of Test Procedure for Measuring the Fuel Consumption of Production-Model FCVs

2019-04-02
2019-01-0382
Factors affecting the measurement of the fuel consumption of FCVs were analyzed to reveal their sensitivity. The method for measuring fuel consumption described in WLTP is to measure the hydrogen consumption by using an electric precision balance and off-vehicle tanks (not on-vehicle tanks). This is unique compared with conventional vehicles such as petrol-engine vehicles and pure-electric vehicles. Therefore, we examined the sensitivities of the effect of hydrogen consumption determination, the effect of hydrogen supply pipe design, and the effect of hydrogen supply pipe management. The experiments were conducted with two production models of FCVs having different FC management systems. The effects were quantitatively evaluated by comparing the fuel consumption rate driving in WLTC.
Technical Paper

Development of Virtual Fuel Economy Trend Evaluation Process

2019-04-02
2019-01-0510
With the advance of the autonomous vehicle development, the possibilities to improve fuel economy increased significantly by changing the driver or powertrain response under different traffic conditions. Development of new fuel-efficient driving strategies requires extensive experiments and simulations in the traffic. In this paper, a fuel efficiency simulator environment with existing simulator software such as Simulink, Vissim, Sumo, and CarSim will be developed to reduce the effort for developing new fuel-efficient algorithms. Simulation environment will be created by combining a mid-sized sedan MATLAB-Simulink model with a realistic traffic simulation. To simulate the traffic realistically, real roads from urban and highway sections will be modeled in the simulator with different traffic densities.
Technical Paper

Real-time Reinforcement Learning Optimized Energy Management for a 48V Mild Hybrid Electric Vehicle

2019-04-02
2019-01-1208
Energy management of hybrid vehicle has been a widely researched area. Strategies like dynamic programming (DP), equivalent consumption minimization strategy (ECMS), Pontryagin’s minimum principle (PMP) are well analyzed in literatures. However, the adaptive optimization work is still lacking, especially for reinforcement learning (RL). In this paper, Q-learning, as one of the model-free reinforcement learning method, is implemented in a 48V mild hybrid electric vehicle (HEV) framework to optimize the fuel economy. Different from other RL work in HEV, this paper considers not only battery state-of-charge (SOC), but also vehicle speed and vehicle torque demand as the Q-learning states. In the cost function definition, the fuel consumption contains engine fuel consumption and equivalent battery fuel consumption, which shares the idea with ECMS. The Q-value table is trained over one driving cycle multiple times. During the training process, the exploration and exploitation is discussed.
Technical Paper

Simulation of Speedometer and Odometer Calibration as per Standard Recommended Practices

2019-04-02
2019-01-1249
In current scenario, delivering the right product at right time is very crucial in rapidly growing automotive sector to grab the competitive advantage. In the development phase, validation process takes most of the product development time. Any change in driveline system like Gearbox, drive head or tyre will call for speedometer and odometer test as per legislative requirements. This paper aimed on reducing the validation time for speedometer and odometer calibration of commercial vehicles. New simulation test facility is designed and developed for Speedometer and Odometer calibration which brings agility in validation process and helps in reducing development time. It avoids physical test at test track, workshop technician activities, reduces driver fatigue and fuel consumption.
Technical Paper

Optimizing Performance and Fuel Efficiency for a Formula SAE Car

2019-04-02
2019-01-1127
This paper presents a system intended to optimize a balance between performance and efficiency of a vehicle completing a course. For example, the Formula SAE competition includes an endurance event where 100 points are based on fuel efficiency and 275 points are based on performance. While lap simulation programs are typically used to decrease lap times by modifying the car’s design parameters, our goal is a lap simulation tool that can also be used to maximize the fuel efficiency while maintaining a prescribed performance level. In the FSAE event, if the fuel consumption can be reduced enough while maintaining a comparable lap time the overall score can increase dramatically. The simulation presented will optimize gear shifts, maximum throttle position, and fuel mixture to achieve the highest score for endurance and efficiency combined.
Technical Paper

Engine-Aftertreatment in Closed-Loop Modeling for Heavy Duty Truck Emissions Control

2019-04-02
2019-01-0986
An engine-aftertreatment computational model was developed to support in-loop performance simulations of tailpipe emissions and fuel consumption associated with a range of heavy-duty (HD) truck drive cycles. For purposes of this study, the engine-out exhaust dynamics were simulated with a combination of steady-state engine maps and dynamic correction factors that accounted for recent engine operating history. The engine correction factors were approximated as dynamic first-order lags associated with the thermal inertia of the major engine components and the rate at which engine-out exhaust temperature and composition vary as combustion heat is absorbed or lost to the surroundings. The aftertreatment model included catalytic monolith components for diesel exhaust oxidation, particulate filtration, and selective catalytic reduction of nitrogen oxides (NOx) with urea.
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