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Technical Paper

Multi Attribute Balancing of NVH, Vehicle Energy Management and Drivability at Early Design Stage Using 1D System Simulation Model

2019-01-09
2019-26-0178
Improving fuel efficiency often affects NVH performance. Modifying a vehicle’s design in the latter stages of development to improve NVH performance is often costly. Therefore, to optimize the cost performance, a Multi-Attribute Balancing (MAB) approach should be employed in the early design phases. This paper proposes a solution based on a unified 1D system simulation model across different vehicle performance areas. In the scope of this paper the following attributes are studied: Fuel economy, Booming, Idle, Engine start and Drivability. The challenges to be solved by 1D simulation are the vehicle performance predictions, taking into account the computation time and accuracy. Early phase studies require a large number of scenarios to evaluate multiple possible parameter combinations employing a multi-attribute approach with a systematic tool to ease setup and evaluation according to the determined performance metrics.
Technical Paper

A Reduced Order Model for a Passenger Car Turbo Charging System and Application to Engine Output Torque Profile Control

2015-09-01
2015-01-1981
Downsizing engines with a turbocharging system have been widely applied to passenger cars to improve fuel economy. Engine torque response to accelerator operation is one of important features in addition to steady state performance of the system. Torque profile management for turbocharged internal combustion engines is one of required technologies. A turbocharging system for a car is a system with a positive feedback loop in which compressed air drives the compressor after the combustion process. A reduced order model was derived for the charging system. Pressure ratio of a compressor is proportional to square of turbine speed and the turbine speed is a first order delay system to throttle opening in the model. Model structure was designed from mathematical equations that describe turbine and compressor works. Model parameters were identified from measured data. An output torque profile control strategy based on the derived model is investigated.
Journal Article

A Study on Knocking Prediction Improvement Using Chemical Reaction Calculation

2015-09-01
2015-01-1905
Compression ratio of newly developed gasoline engines has been increased in order to improve fuel efficiency. But in-cylinder pressure around top dead center (TDC) before spark ignition timing is higher than expectation, because the low temperature oxidization (LTO) generates some heat. The overview of introduced calculation method taking account of the LTO heat of unburned gas, how in-cylinder pressure is revised and some knowledge of knocking prediction using chemical kinetics are shown in this paper.
Technical Paper

A Study on Practical Use of Diesel Combustion Calculation and Development of Automatic Optimizing Calculation System

2015-09-01
2015-01-1845
A KIVA code which is customized for passenger car's diesel engines is linked with an engine performance simulator and demonstrated with our optimizing calculation system. Aiming to fulfill our target calculation speed, the combustion model of the KIVA code is changed from a chemical reaction calculation method to a chemical equilibrium calculation method which is introduced a unique technique handling chemical species maps. Those maps contain equilibrium mole fraction data of chemical species according to equivalence ratio and temperature. Linking the KIVA code to the engine simulator helps to evaluate engine performance by indicated mean effective pressure (IMEP). The optimizing calculation system enables to obtain response surfaces. Observing the response surfaces, clear views of engine performance characteristics can be seen. The overview of this calculation system and some examples of the calculation are shown in this paper.
Technical Paper

Human Driving Behavior Analysis and Model Representation with Expertise Acquiring Process for Controller Rapid Prototyping

2011-04-12
2011-01-0051
Driving car means to control a vehicle according to a target path, e.g. road and speed, with some constraints. Human driving models have been proposed and applied for simulations. However, human control in driving has not been analyzed sufficiently comparing with that of machine control system in term of control theory. Input - output property with internal information processing is not easily measured and described. Response of human driving is not as quicker as that of machine controller but human can learn vehicle response to driving operation and predict target changes. Driving behavior of an expert driver and a beginner in an emission test cycle was measured and difference in target speed tracking was looked into with performance indices. The beginner's operation was less stable than that of the expert. Transfer function of the vehicle system was derived based on linearized model to investigate human driving behavior as a tracking controller in the system.
Journal Article

Role of Predictive Engineering in the Design Evolution of a Thermoplastic Fender for a Compact SUV

2011-04-12
2011-01-0768
Automotive fenders is one such example where specialized thermoplastic material Noryl GTX* (blend of Polyphenyleneoxide (PPO) + Polyamide (PA)) has successfully replaced metal by meeting functional requirements. The evolution of a fender design to fulfill these requirements is often obtained through a combination of unique material properties and predictive engineering backed design process that accounts for fender behavior during the various phases of its lifecycle. This paper gives an overview of the collaborative design process between Mitsubishi Motors Corporation and SABIC Innovative Plastics and the role of predictive engineering in the evolution of a thermoplastic fender design of Mitsubishi Motors Corporation's compact SUV RVR fender launched recently. While significant predictive work was done on manufacturing and use stage design aspects, the focus of this paper is the design work related to identifying support configuration during the paint bake cycle.
Technical Paper

NOx Trap Catalyst Technologies to Attain 99.5% NOx Reduction Efficiency for Lean Burn Gasoline Engine Application

2009-04-20
2009-01-1077
For fuel economy improvement by lean-burn gasoline engines, extension of their lean operation range to higher loads is desirable as more fuel is consumed during acceleration. Urgently needed therefore is development of emission control systems having as high NOx conversion efficiency as three-way catalysts (TWC) even with more frequent lean operation. The authors conducted a study using catalysts loaded with potassium (K) as the only NOx trapping agent in an emission control system of a lean-burn gasoline engine.
Technical Paper

Grammatical Evolution Based Tool for Predicting Multivariable Response Surface for Laser Lap Welding

2008-04-14
2008-01-1372
The problem of predicting the quality of weld is critical to manufacturing. A great deal of data is collected under multiple conditions to predict the quality. The data generated at Daimler Chrysler has been used to develop a model based on grammatical evolution. Grammatical Evolution Technique is based on Genetic Algorithms and generates rules from the data which fit the data. This paper describes the development of a software tool that enables the user to choose input variables such as the metal types of top and bottom layers and their thickness, intensity and speed of laser beam, to generate a three dimensional map showing weld quality. A 3D weld quality surface can be generated in response to any of the two input variables picked from the set of defining input parameters. This tool will enable the user to pick the right set of input conditions to get an optimal weld quality. The tool is developed in Matlab with Graphical User Interface for the ease of operation.
Technical Paper

Direct Simulation for Aerodynamic Noise from Vehicle Parts

2007-08-05
2007-01-3461
Flows around a forward facing step and a fence are simulated on structured grid to estimate aerodynamic noise by using direct simulation. Calculated results of sound pressure level show quantitatively good agreement with experimental results. To estimate aerodynamic noise from 3D complex geometry, a simplified side mirror model is also calculated. Averaged pressure distribution on the mirror surface as well as pressure fluctuations on the mirror surface and ground are simulated properly. However, calculated result of sound pressure level at a location is about 20dB higher than experiment due to insufficient spatial resolution. To capture the propagation of sound waves, more accuracy seems to be required.
Technical Paper

New DOC for Light Duty Diesel DPF System

2007-07-23
2007-01-1920
A new state of the art DOC (Diesel Oxidation Catalyst) having superior light-off and exothermic activity for forced regeneration compared to conventional Pt base passive DOC, was investigated for LDD application. The DOC uses the latest Pt/Pd technology resulting cost effective DPF system. The newly developed DOC demonstrated improved catalytic activities from Pt only DOC in model gas or engine bench tests. In this study, DOC at early development stage showed excellent light-off activity in model gas and engine bench test compared to conventional Pt only DOC, however, it showed “extinction” phenomenon which is one of the deactivation mode while the post injection and it was observed when post injection operation was done at lower DOC inlet temperatures, e.g. below 250 C. Temperature profiles along diameter and length into DOC bed while active regeneration suggested extinction would be caused by fouling of supplied hydrocarbons derived from diesel fuel.
Technical Paper

A Study of Transmission fluid Performance on Fuel Economy

2007-07-23
2007-01-1980
To apply a fuel economy performance to AT&CVT fluid for common use (hereinafter AT/CVT fluid) and manual transmission fluid, by optimizing fluid viscosity, a fundamental study was investigated. Generally, it is well known that the viscosity of polymer-added transmission fluids is gradually reduced, due to deterioration of the viscosity index improver caused by shear stress. An excessive viscosity reduction causes an operation failure or damage to the transmission. Considering above factor, the authors focused attention on the potential of a low viscosity formulation to improve fuel efficiency by reducing an internal stirring-resistance of the transmission. Also from the viewpoint of friction characteristics, the performance of a base oil was studied. Utilizing the EHL (Elast-Hydrodynamic Lubrication) tester [1] and vehicle tests, the performance of base oils was evaluated for the fluid development.
Technical Paper

Improving Low Frequency Torsional Vibrations NVH Performance through Analysis and Test

2007-05-15
2007-01-2242
Low frequency torsional vibrations can be a significant source of objectionable vehicle vibrations and in-vehicle boom, especially with changes in engine operation required for improved fuel economy. These changes include lower torque converter lock-up speeds and cylinder deactivation. This paper has two objectives: 1) Examine the effect of increased torsional vibrations on vehicle NVH performance and ways to improve this performance early in the program using test and simulation techniques. The important design parameters affecting vehicle NVH performance will be identified, and the trade-offs required to produce an optimized design will be examined. Also, the relationship between torsional vibrations and mount excursions, will be examined. 2) Investigate the ability of simulation techniques to predict and improve torsional vibration NVH performance. Evaluate the accuracy of the analytical models by comparison to test results.
Technical Paper

Application of the Modal Compliance Technique to a Vehicle Body in White

2007-05-15
2007-01-2355
This paper describes the application of the modal compliance method to a complex structure such as a vehicle body in white, and the extension of the method from normal modes to the complex modes of a complete vehicle. In addition to the usual bending and torsion calculations, the paper also describes the application of the method to less usual tests such as second torsion, match-boxing and breathing. We also show how the method can be used to investigate the distribution of compliance throughout the structure.
Technical Paper

Experimental Modal Methodologies for Quantification of Body/Chassis Response to Brake Torque Variation

2007-05-15
2007-01-2343
Brake torque variation is a source of objectionable NVH body/chassis response. Such input commonly results from brake disk thickness variation. The NVH dynamic characteristics of a vehicle can be assessed and quantified through experimental modal testing for determination of mode resonance frequency, damping property, and shape. Standard full vehicle modal testing typically utilizes a random input excitation into the vehicle frame or underbody structure. An alternative methodology was sought to quantify and predict body/chassis sensitivity to brake torque variation. This paper presents a review of experimental modal test methodologies investigated for the reproduction of vehicle response to brake torque variation in a static laboratory environment. Brake caliper adapter random and sine sweep excitation input as well as body sine sweep excitation in tandem with an intentionally locked brake will be detailed.
Technical Paper

NVH Refinement of Diesel Powered Sedans with Special Emphasis on Diesel Clatter Noise and Powertrain Harshness

2007-05-15
2007-01-2378
NVH refinement of passenger vehicles is crucial to customer acceptance of contemporary vehicles. This paper describes the vehicle NVH development process, with specific examples from a Diesel sedan application that was derived from gasoline engine-based vehicle architecture. Using an early prototype Diesel vehicle as a starting point, this paper examines the application of a Vehicle Interior Noise Simulation (VINS) technique in the development process. Accordingly, structureborne and airborne noise shares are analyzed in the time-domain under both steady-state and transient test conditions. The results are used to drive countermeasure development to address structureborne and airborne noise refinement. Examples are provided to highlight the refinement process for “Diesel knocking” under idle as well as transient test conditions. Specifically, the application of VINS to understanding the influence of high frequency dynamic stiffness of hydro-mounts on Diesel clatter noise is examined.
Technical Paper

Simulation Process to Investigate Suspension Sensitivity to Brake Judder

2007-04-16
2007-01-0590
Brake judder, which is a low frequency excitation of the suspension and thus, the body structure during low-G braking, is mainly felt at the steering wheel and throughout the vehicle structure. Brake judder is a problem that costs manufacturers millions of dollars in warranty cost and undesirable trade offs. The magnitude of judder response depends not only on the brake torque variation, but also on the suspension design character-istics. This paper discusses the judder simulation process using ADAMS software to investigate the suspension design sensitivity to the first order brake judder performance. The paper recommends “tuning knobs” to suspension designers and vehicle development engineers to resolve issues in the design and development stages. Various suspension design varia-bles including geometry and compliances as well as brake related characteristics were investigated.
Technical Paper

Sensitivity Analysis of Powertrain Cooling System Performance

2007-04-16
2007-01-0598
This paper identifies the difference in powertrain cooling system content levels using a nominal and a +3 Standard deviation maximum temperature design approach. Variation simulation analysis tools are used along with a 1-D cooling system performance model to predict resulting temperature distribution for different combinations of input variable populations. The analysis will show differential in powertrain cooling system content, mass, and impact to fuel economy for a nominal vs. +3 sigma design approach.
Technical Paper

Robust Optimization of Engine Lubrication System

2007-04-16
2007-01-1568
The quality of engine lubrication depends upon how much oil is supplied and how the lubricant is pressurized to the lubricated components. These variables strongly affect the safe operation and lifespan of an engine. During the conceptual design stage of an engine, its lubrication system cannot be verified experimentally. It is highly desirable for design engineers to utilize computer simulations and robust design methodology in order to achieve their goal of optimizing the engine lubrication system. The heuristic design principle is a relatively routine resource for design engineers to pursue although it is time consuming and sacrifices valuable developing time. This paper introduces an unusual design methodology in which design engineers were involved in analyzing their own designs along with lubrication system analyst to establish a link between two sophisticated software packages.
Technical Paper

Optimization of Head Impact Waveform to Minimize HIC

2007-04-16
2007-01-0759
To mitigate head impact injuries of vehicle occupants in impact accidents, the FMVSS 201 requires padding of vehicle interior so that under the free-moving-head-form impact, the head injury criterion (HIC) is below the limit. More recently, pedestrian head impact on the vehicle bonnet has been a subject being studied and regulated as requirements to the automobile manufacturers. Over the years, the square wave has been considered as the best waveform for head impacts, although it is impractical to achieve. This paper revisits the head impact topic and challenges the optimality of aiming at the square waveform. It studies several different simple waveforms, with the objective to achieve minimal HIC or minimal crush space required in head-form impacts. With that it is found that many other waveforms can be more efficient and more practical than the square wave, especially for the pedestrian impact.
Technical Paper

Effect of Cross Flow on Performance of a PEM Fuel Cell

2007-04-16
2007-01-0697
A serpentine flow channel is one of the most common and practical channel layouts for a PEM fuel cell since it ensures the removal of water produced in a cell. While the reactant flows along the flow channel, it can also leak or cross to neighboring channels via the porous gas diffusion layer due to a high pressure gradient. Such a cross flow leads to effective water removal in a gas diffusion layer thus enlarging the active area for reaction although this cross flow has largely been ignored in previous studies. In this study, neutron radiography is applied to investigate the liquid water accumulation and its effect on the performance of a PEM fuel cell. Liquid water tends to accumulate in the gas diffusion layer adjacent to the flow channel area while the liquid water formed in the gas diffusion layer next to the channel land area seems to be effectively removed by the cross leakage flow between the adjacent flow channels.
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