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Technical Paper

Method of NVH Quality Rating of Diesel Combustion Noise Using Typical Driving Modes

2009-05-19
2009-01-2078
The development of a new method to evaluate the NVH quality of diesel combustion noise bases upon following questions by regarding typical driving modes: Driving behavior with diesel vehicles Which driving situation causes an annoying diesel combustion noise Judgment of diesel combustion noise as good or bad A suitable test course was determined to regard typical driving situations as well as the European driving behavior. Vehicles of different segments were tested on that course. The recorded driving style and the simultaneously given comments on the diesel combustion noise results to a typical driving mode linked to acoustics sensation of diesel combustion noise. The next step was to simulate this driving mode on the chassis dynamometer for acoustical measurements. The recordings of several vehicles were evaluated in listening test to identify a metric. The base of metric was objective analyses evaluating diesel combustion noise in relevant driving situations.
Technical Paper

Reduction of Interior Booming Noise for a Small Diesel Engine Vehicle without Balance Shaft Module

2009-05-19
2009-01-2121
Applying BSM (Balance shaft module) is a very common and effective way to reduce the 2nd-order powertrain vibration which is caused by the ill-balanced inertia force due to the oscillating masses inside an engine. However, the adoption of a BSM can also produce undesirable things especially in cost, fuel economy, starting performance, and so on. Therefore, for small vehicles, in which case cost and weight are key factors at the development stage, it is often required to develop competitive NVH performance without the expensive apparatus like a BSM. In this paper, in order to develop interior noise and vibration of a 4-cylinder vehicle without a BSM, we analyzed the contribution of some transfer paths for powertrain vibration, and could reduce interior booming noise by tuning the dynamic characteristic of the engine mount which was one of the largest transfer paths.
Technical Paper

Development of Mild Hybrid City Bus with a Single Voltage Source of 28 V

2008-04-14
2008-01-0086
The most popular issues nowadays in the automotive industry include reduction of environmental impacts by emission materials from automobiles as well as improvement of fuel economy. This paper deals with development of a ¡mild-hybrid¡ system for a city bus as an effort to increase fuel economy in a relatively reasonable expense. Three different technical tactics are employed; an engine is shut down at an engine idle state, a vehicle kinetic energy when the bus is decelerated is re-saved to a battery in the form of electricity, and finally the radiator cooling fan is operated by an electric motor using the saved electric energy with an optimal speed control. It has been demonstrated through the driving tests in a specific city mode, ¡Suwon city mode¡, that an average fuel economy is improved more than 12%, and the system can be a feasible choice in a city bus running in a city mode experiencing many stop and go¡s.
Technical Paper

Performance Design of Low Temperature Condenser for Waste Heat Recovery System

2013-03-25
2013-01-0046
The optimum design process of the low-temperature condenser of a dual-loop waste heat recovery system with Rankine steam cycles for improving the fuel efficiency of gasoline automobiles has been investigated. The waste heat recovery system consists of a high-temperature (HT) loop in which water as the HT working fluid recovers waste heat only from the exhaust gas of about 700°C and a low-temperature (LT) loop in which a refrigerant as the LT working fluid recovers heat dissipation from the HT loop, and waste heat from the engine coolant of relatively low temperature. The low temperature condenser plays a role to dissipate heat from the system by condensing the low temperature loop working fluid sufficiently.
Technical Paper

Development of Engine Control Using the In-Cylinder Pressure Signal in a High Speed Direct Injection Diesel Engine

2011-04-12
2011-01-1418
Emissions regulations are becoming more severe, and they remain a principal issue for vehicle manufacturers. Many engine subsystems and control technologies have been introduced to meet the demands of these regulations. For diesel engines, combustion control is one of the most effective approaches to reducing not only engine exhaust emissions but also cylinder-by-cylinder variation. However, the high cost of the pressure sensor and the complex engine head design for the extra equipment are stressful for the manufacturers. In this paper, a cylinder-pressure-based engine control logic is introduced for a multi-cylinder high speed direct injection (HSDI) diesel engine. The time for 50% of the mass fraction to burn (MFB50) and the IMEP are valuable for identifying combustion status. These two in-cylinder quantities are measured and applied to the engine control logic.
Technical Paper

The Effects of Injection Timing and Piston Bowl Shape on PHCCI Combustion with Split injections

2010-04-12
2010-01-0359
To reduce diesel engine emissions, a split injection strategy with PHCCI combustion in a diesel engine was investigated with simulation. A multidimensional CFD application, Star-CD coupled with a modified 2-D flamelet was used to simulate multiple injection combustion. Several mass ratios of the first injection and second injection conditions compared to the conventional pilot and main injection strategy were evaluated. The injection angle and the injection timing of the first injection were fixed to 150° and 55° BTDC, respectively. Because of the early injection, the in-cylinder pressure and temperature were much lower than those of normal injection conditions, and the fuel could not fully evaporate. As a result, wall impingement can be occurred, and THC and CO would be increased. To eliminate the wall impingement, the injection timing of the first injection was then retarded to 35-30° BTDC, and the piston bowl geometry was modified to capture droplets in the piston bowl.
Technical Paper

The Unified Relationship between Torque and Gear Ratio and Its Application in Multi-Step Automatic Transmissions

2016-04-05
2016-01-1098
The market demands for CO2 reduction and fuel economy have led to a variety of new gear set concepts of automatic transmissions with 4 planetary gear sets and 6 shift elements in recent years. Understanding the relationship between the torque of clutch and brake and gear ratio in the design stage is very important to assess new gear set concepts and to set up the control strategy for enhancing shift quality and to reduce the heat generation of clutch and brake. In this paper, a new systematic approach is used to unify the relationship between torque and gear ratio during the gear shift for all multi-step planetary automatic transmissions. This study describes the unified concept model with a lumped inertia regardless of the specific transmission layout and derives the principal unified relationship equations using torque and energy analysis, which prove that the sum of brake torque is always gear ratio -1 in every in-gear.
Technical Paper

The CAE Analysis of a Cylinder Head Water Jacket Design for Engine Cooling Optimization

2018-04-03
2018-01-1459
Hyundai's new engine is developed which optimize the cooling efficiency for knocking improvement and friction reduction. The cooling concepts for this purpose are 1) equalizing the temperature among cylinders by flow optimization, 2) cooling the required area intensively, 3) adopting ‘active flow control’ and 4) enlarging fuel economy at high speed range. In order to realize the cooling concept, 1) cross-flow, 2) compact water jacket & exhaust cooling, 3) flow control valve and 4) cylinder head with integrated exhaust manifold are considered. Improvement of knocking and friction reduction by increased cooling water temperature makes fuel efficiency possible. On the other hand, in order to strengthen the cooling around the combustion chamber and to reduce the deviation among the combustion chamber of cylinders, it is required to design the head water jacket shape accordingly.
Technical Paper

Development of Multi-Functioning Lean NOx Trap Catalysts for the On-board NH3 Generation

2018-04-03
2018-01-1430
Improved Lean NOx Trap (LNT) catalysts with enhanced NH3 generation feature were developed for the small diesel engine. The next generation LNT system needs to perform good NOx conversions over the wide temperature range including below 200°C for urban driving and above 400°C for motorway of real road driving. However, the extended use of BaO, a component of LNT known to be very effective for high temperature NOx storage, results in the decrease of low temperature NOx conversion due to the degradation of NO oxidation associating with sulfur over time. The improvement of the low-temperature LNT performance is a key requirement for the real driving emission control as the best operation temperature for urea-SCR is above ~250°C. In this study, our next generation LNT with new washcoat architecture has demonstrated improved NOx removal efficiencies under the wider operation temperature window than the current production technology.
Technical Paper

Understanding 3 Cylinder CVT Vehicle for Improving Fuel Economy and Reducing Noise and Vibration

2016-04-05
2016-01-1294
This study presents the NVH characteristics of a passenger vehicle with a three-cylinder engine and a Continuously Variable Transmission (CVT) and an optimization procedure to achieve balance between fuel economy and NVH. The goal of this study is to improve fuel economy by extending the lock-up area of the damper clutch at low vehicle speed and to minimize booming noise and body vibration caused by the direct connection of the engine and transmission. Resonance characteristics of the chassis systems and driveline have been studied and optimized by the experiment. NVH behavior of the vehicle body structure is investigated and modifications for refinement of booming and body vibration are proposed by simulation using MSC NASTRAN. Calibration parameters for CVT control are optimized for fuel economy and NVH. As a result, the lock-up clutch area has been extended by 300RPM and the fuel economy has been improved by about 1%, while the NVH characteristics of the vehicle satisfy the targets.
Technical Paper

A Study of Low-Friction Road Estimation using an Artificial Neural-Network

2018-04-03
2018-01-0811
Road friction estimation algorithms had been studied for many years because it is very important factor for safety control and fuel efficiency of vehicle. But traditional solutions are hard to adapt in automotive industry because their performance is not sufficient enough and expensive to implement. Therefore, this paper proposes a road friction estimation algorithm based on a trained artificial neural-network which is low cost and robust. The suggested method doesn’t need expensive additional sensors such as optical or lidar sensor, also it shows better performance in real car environment compared to other algorithms based on vehicle dynamics. In this paper, we would describe this algorithm in detail and analyze the test results evaluated in real road conditions.
Technical Paper

A Study on the Method to Manage the Weight and Cost of a Vehicle by Adjusting the Parameters of Styling Profile

2018-04-03
2018-01-1025
Since the fuel efficiency of vehicle has become one of the big issues due to environmental pollution problems, many studies have been conducted on various methods such as improving powertrain performance and aerodynamic performance, reducing the weight of the vehicle and so on. There have been many new attempts to reduce weight but mostly about improving material property. In the case of vehicles sharing the same platform, the weight and cost of vehicle are mainly changed by the exterior styling. But, there is no solution to control the exterior styling in terms of the weight and cost of vehicle, yet. The purpose of this study is to find the way to save the weight and cost of vehicle while achieving the various performance and requirements of vehicle (safety, aerodynamics, driver’s visibility and so on) from exterior styling point of view. We focused on the weight difference of the vehicles that shared the platform and were same overall dimensions.
Technical Paper

Combustion Process Analysis in a HSDI Diesel Engine Using a Reduced Chemical Kinetics

2004-03-08
2004-01-0108
The combustion characteristics of a HSDI diesel engine were analyzed numerically using a reduced chemical kinetics. The reaction mechanism consisting of 26 steps and 17 species including the Zel'dovich NOx mechanism for the higher hydrocarbon fuel was implemented in the KIVA-3V. The characteristic time scale model was adopted to account for the effects of turbulent mixing on the reaction rates. The soot formation and oxidation processes are represented by Hiroyasu's model and NSC's model. The validation cases include the homogenous fuel/air mixture and the spray combustion in a constant volume chamber. After the validation, the present approach was applied to the analysis of the spray combustion processes in a HSDI diesel engine. The present approach reasonably well predicts the ignition delay, combustion processes, and emission characteristics in the high-pressure turbulent spray flame-field encountered in the practical HSDI diesel engines.
Technical Paper

Numerical Study of Combustion Processes and Pollutant Formation in HSDI Diesel Engines

2004-03-08
2004-01-0126
The Representative Interactive Flamelet(RIF) concept has been applied to numerically simulate the combustion processes and pollutant formation in the direct injection diesel engine. Due to the ability for interactively describing the transient behaviors of local flame structures with CFD solver, the RIF concept has the capabilities to predict the auto-ignition and subsequent flame propagation in the diesel engine combustion chamber as well as to effectively account for the detailed mechanisms of soot and NOx formation. In order to account for the spatial inhomogeneity of the scalar dissipation rate, the Eulerian Particle Flamelet Model using the multiple flamelets has been employed. Special emphasis is given to the turbulent combustion model which properly accounts for vaporization effects on turbulence-chemistry interaction.
Technical Paper

Development of Fuel Consumption of Passenger Diesel Engine with 2 Stage Turbocharger

2006-04-03
2006-01-0021
High specific power, additional hardware and mapping optimization was done to achieve reduction of fuel economy for current engine in this study. 2 stage turbocharger with serial configuration was best candidate not only for high specific power at high engine speed but also for increase of low end torque for current engine. This increase of low end torque is important for development of transient characteristic of vehicle. DoE and efficient EGR Cooler was applied for optimization of fuel economy. DoE was useful for optimization of fuel consumption affected by various fuel injection parameters. This DoE was also efficient for matching optimal fuel economy after change of engine hardware. Performance improvement of engine with 2 stage turbocharger VGT was evaluated and additional development of fuel economy was performed in this study.
Technical Paper

Control of a Catalyzed Diesel Particulate Filter System III (Engine Bench Accelerated Aging Test Development for a Passenger Car Catalyzed Particulate Filter System)

2006-04-03
2006-01-0422
The key technical aspects of a catalyzed particulate filter (CPF) system development are software calibration for regeneration and component optimization for system performance. It is important that the optimized component specification be selected an early stage since the components have an effect on the overall regeneration strategy. Accordingly, in a catalyzed particulate filter system the washcoat and precious metal loading are main components that should be optimized at an early stage of the system development. An accelerated aging protocol is needed in order to properly evaluate the performance of various catalyst systems in a timely manner.
Technical Paper

Theoretical and Experimental Flow Analysis of Exhaust Manifolds for PZEV

2007-08-05
2007-01-3444
As the current and future emission regulations become stringent, the research on exhaust manifold with CCC (Close Coupled Catalyst) has been the interesting and remarkable subject. To design of exhaust manifold with CCC is a difficult task due to the complexity of the flow distribution caused by the pulsating flows that are emitted at the exhaust ports. This study is concerned with the theoretical and experimental approach to improve catalyst flow uniformity through the basic understanding of exhaust flow characteristics. Computational and experimental approach to the flow for exhaust manifold of conventional cast type, stainless steel bending type with 900 cell CCC system in a 4-cylinder gasoline engine was performed to investigate the flow distribution of exhaust gases.
Technical Paper

Analysis of Transient Thermal and Conversion Characteristics of Dual-Monolith Catalytic Converter with Palladium and Palladium/Rhodium Catalysts

2007-08-05
2007-01-3453
We used a one-dimensional monolithic catalyst model to predict the transient thermal and conversion characteristics of a dual monolithic catalytic converter with a Palladium only (Pd-only) catalyst and a Palladium/Rhodium (Pd/Rh) catalyst. Prior to the numerical investigation of the dual-catalyst converter, we modified the pre-exponential factor and activation energy of each reaction for both catalysts to achieve acceptable agreement with experimental data under typical operating conditions of automobile applications. We validated the conversion behavior of the lumped parameter model for each catalyst against different engine operating conditions. Two higher cell density substrates, Pd-only catalyst (600cpsi/3.9mil) and Pd/Rh catalyst (600cpsi/4mil), for faster light-off and improved warm-up performance are used in this study and the two monoliths has been connected without the space between monoliths.
Technical Paper

A Characteristics of Particle Number Distribution for the Urea Solution Injection to Urea SCR System of Commercial Diesel Engine for an Emission Regulation

2007-08-05
2007-01-3455
While the request of diesel engine is recently increased due to its excellent fuel economy benefit, the regulation of emission becomes reinforced. The variety of method such as engine technologies and aftertreatment systems have been developed and applied to meet the criteria of regulation so far. One of recognizable technologies utilized in a heavy commercial vehicle is SCR system using urea solution as a reductant, which eliminates NOx. This paper includes the experiment of a diesel engine equipped with Urea SCR system, and its emission characteristic including particle is analyzed and evaluated against its regulation. This evaluation is performed for the diesel engine using ELPI(Electric Low Pressure Impactor) under the condition of constant engine RPM and load, and injecting urea solution to SCR system, particle number distribution of particle range from 7nm to 10μm was estimated.
Technical Paper

Design and Development of a Spray-guided Gasoline DI Engine

2007-08-05
2007-01-3531
Adopting the Spray-guided Gasoline Direct Injection (SGDI) concept, a new multi-cylinder engine has designed. The engine has piezo injectors at the central position of its combustion chamber, while sparkplugs are also at the center. The sparkplug location is designed so that the spark location is at the outer boundary of the fuel spray where the appropriate air-fuel mixture is formed. A few important operating parameters are chosen to investigate their effects on the combustion stability and fuel consumption. The final experimental results show a good potential of the SGDI engine; the fuel consumption rate was much less than that of the base Multi Port Injection (MPI) engine at various engine operating conditions.
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