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Technical Paper

Development of Vehicle Thermal Management Model for Improving the Energy Efficiency of Electric Vehicle

2022-03-29
2022-01-0201
Recently, automobile manufacturers are interested in the development of battery electric vehicle (BEV) having a longer mileage to satisfy customer needs. The BEV with high efficiency depends on the temperature of the electric components. Hence it is important to study the effect of the cooling system in electric vehicle in order to optimize efficiency and performance. In this study, we present a 1-D vehicle thermal management (VTM) simulation model. The individual vehicle subsystems were modeled including cooling, power electric (PE), mechanical, and control components. Each component was integrated into a single VTM model and it would be used to calculate energy transfer among electrical, thermal, and mechanical energy. As a result, this simulation model predicts a plenty of information including the state of each component such as temperature, energy consumption, and operating point about electric vehicle depending on driving cycles and environmental conditions.
Technical Paper

A Conceptual Analysis in the Early Design Stage for the Roadnoise Reduction using FRF Based Substructuring

2022-03-29
2022-01-0312
NVH analysis based on numerical simulations before making test vehicles has become common process in the automotive industry. Furthermore, the latest trend has been going beyond numerical simulations using 3-D design drawing data, and is extending to the conceptual study in the initial design stage. If reasonable information is provided to make a better decision on the design concept at the very early stage of vehicle development, subsequent design processes can be carried out more efficiently. Therefore, the core of this trend is to predict vehicle performances at the conceptual design stage without drawing data, and then to lead the design progress based on this result. From this point of view, FBS (FRF Based Substructuring) methodology has potential to be used for the conceptual design.
Technical Paper

Development of a Prediction Model for Tire Tread Pattern Noise based on Convolutional Neural Network with RMSProp Algorithm.

2022-03-29
2022-01-0884
It has changed from an internal combustion engine to an electric vehicle(EV) so the exterior noise of the engine and exhaust system is removed and the tire pattern noise becomes the main noise source contributor for EV traveling at speeds above 50 kph and 80 kph. It is very useful to predict tire pattern noise performance in the early tire design stage. An artificial neural network model was recently used for the prediction of tire pattern noise. The ANN used the supervised training method, in which features are extracted by applying Gaussian curve fitting to the tread profile spectra of tire patterns; these are then used as the inputs of the ANN. Nevertheless, this method requires the laser scanning of the patterns of real tires, which are non-existent as they are still in the early design stage.
Technical Paper

Development of the Frontal Crash Performance of Vehicle by Simplified Crash Model

2022-03-29
2022-01-0871
This study presents a design methodology to predict the crash behavior of mid-size sedan with a simplified crash model. Without detailed conventional finite element, the simplified crash model can be adopted in the early stage of the vehicle design. Designing vehicle structure to satisfy crash performance target is highly complex problem in the early design stage, because of the nonlinear mechanical behavior, high number of degrees-of-freedom, lack of information and boundary conditions changing over the following development process. In this study, the front structure of the vehicle is divided into load-carrying members and the rigid element through the analysis of load-carrying mechanism, and its physical property (force-displacement relation) is parameterized as the property of the non-linear discrete beam element of the LS-DYNA. The effectiveness of the proposed research is shown by the example of the mid-size sedan.
Technical Paper

A Development of Spindle drive power trunk lid system with Optimizing operation noise

2022-03-29
2022-01-0759
The power trunk lid system is a device that automatically opens and closes the trunk lid using a motor, for the purpose to improve user’s convenience. The technology was applied only to high-priced large cars such as Equus and Genesis, but in line with increasing preference for high convenience features, the scope of application is gradually expanding to semi-large and mid-size vehicles. Accordingly, the need to secure profitability through cost reduction emerged, and we developed a power trunk lid system using a spindle drive. Spindle drives can reduce costs by optimizing the required motor specifications compared to conventional swing arm drives, and are lightweight and easy to assemble. However, since a planetary gear with a high gear ratio is used and the rotational speed of the motor is generally high, it has a relatively low characteristic in terms of actuating noise.
Technical Paper

Development of a Built-in Type Dashboard Camera with Reliability and Usability

2022-03-29
2022-01-0111
Dashcam, which is considered essential parts of vehicles in Korea, are installed in most vehicles for reasons such as accidents, evidence of threatened driving of other vehicles, and insurance premiums. Aftermarket dashcam have been developed with many improvements such as higher resolution camera and LCD application, but still have problems in usability and durability. The first problem is a separate device mounted on the top of the windshield, which obstructs the driver's view and may injure the driver due to a collision impact. In addition, the connection of the power supply may cause a vehicle breakdown such as a fire due to a worker's mistake or a product defect. Secondly, in order to view the stored video, it is troublesome to remove the SD card and check it on the computer. Moreover, since the LCD is so small, it is difficult to search and play the desired video from the list in many saved files.
Technical Paper

Body Cross-Sectional Stiffness Criteria for the Optimal Development of the BIW Weight and Torsional Stiffness

2021-04-06
2021-01-0797
Body-in-white plays a key role in protecting passengers in the event of collision between vehicles, and also endures external forces during cornering in a vehicle. Stiffness of body-in-white is the basic characteristic of a car body, and it is closely related to the full-vehicle-level performance such as body durability, ride and handling, etc. There have been many attempts to correlate body stiffness to full-vehicle-level performance, and studying the relationship between torsional body stiffness and durability has been the popular topic among others. In general, it is believed to be true that bodies with high torsional stiffness exhibit good durability performance, and in many cases this assumption seems to be verified. However, not all cases are true to this assumption. In this paper, relationship between torsional body stiffness and body durability has been closely studied.
Technical Paper

A Performance Design of Constant Pressure Type Exhaust Brake

2021-04-06
2021-01-0398
In commercial vehicles, the exhaust brake assists the service brake to share the excess load and is used as an auxiliary brake to assist with the safety of the engine and the service brake on downhill slopes. To meet the customer's demand for auxiliary brakes, the specification of auxiliary brakes must be determined at the product proposal stage. In this study, performance design was conducted to derive exhaust brake specifications that fit the customer's requirements. For performance design, a system model was created and key design factors with high performance contribution were extracted. Optimal specifications were derived from parameter studies for key design factors. Additionally, performance analysis was performed with design tolerances using the performance design model. Performance was verified through actual vehicle evaluation and design specifications were confirmed.
Technical Paper

A Development of the Driver IC in LED Rear Combination Lamp for Circuit Standardization

2021-04-06
2021-01-0850
Today, many automakers are using LED lamp sources in exterior lamps to establish brand awareness and introduce specialized lamp designs. These eye-catching LED lamp source solutions require many control functions as the lamp functions are diversified and advanced, and accordingly the requirements for standardization and optimization of controllers are increasing. In particular, our LED rear combination lamps have a variety of LED loads according to the design of the lamp model, the installation position, and the diagnostic regulations, so that the design complexity and the number of specifications of the controller are increased [4]. In recent years, more and more aesthetic designs and new technologies are used by various automakers to optimize their controllers in cooperation with global partners to optimize costs [1].
Technical Paper

Robust Control of Commercial Vehicle’s Speed Using Disturbance Observer

2021-04-06
2021-01-0966
This paper proposes a speed controller using a disturbance observer to regulate the speed of a commercial vehicles, and presents vehicle test results to evaluate the performance of the proposed controller. Most ADAS (Advanced Driver Assistance System) and automated driving systems need to reliably regulate the vehicle's speed under any circumstances. A conventional PID controller is commonly used to control the vehicle speed, but performance of it varies depending on changes in external conditions. Commercial vehicles are even more susceptible to these changes than passenger cars and more difficult to obtain an accurate plant model. Considering these features, a speed controller using a disturbance observer is designed for commercial vehicles. The proposed controller treats changes in external conditions as disturbances. The modeling uncertainty is also treated as a disturbance.
Technical Paper

Integrated Control of In-Wheel Motor and Electronic Limited Slip Differential for Lateral Stability and Maneuverability

2021-04-06
2021-01-0974
This paper presents an integrated control of in-wheel motor (IWM) and electronic limited slip differential (eLSD) to enhance the vehicle lateral stability and maneuverability. The two actuators are utilized in the proposed controller to achieve separate purposes. The IWM controller is designed to modify the understeer gradient for enhanced handling characteristic and maneuverability. The eLSD controller is devised to improve the lateral stability to prevent oversteer in a severe maneuver. The proposed controller consists of a supervisor, upper-level controller and lower-level controller. The supervisor determines a target motion based on a target understeer gradient for IWM control and a yaw rate reference for eLSD control. The upper-level controller generates a desired yaw moment for the target motion. In the lower-level controller, the desired yaw moment is converted to the control inputs for IWMs in the two front wheels and eLSD at the rear axle.
Journal Article

On the Aerodynamics of the Notchback Open Cooling DrivAer: A Detailed Investigation of Wind Tunnel Data for Improved Correlation and Reference

2021-04-06
2021-01-0958
Since the introduction of the DrivAer in 2012 this model has become the standard generic aerodynamic benchmark and aerodynamic research model used by automotive OEMs, software vendors and researchers. In 2017, the relevance of the DrivAer has been furthered by the inclusion of a simplified engine bay. Whilst the DrivAer has become the popular standard, the availability of detailed wind tunnel test data, a key enabler for more sophisticated aerodynamic benchmarking and research, remains limited. This paper presents a comprehensive set of wind tunnel test data of the notchback version of the Ford Open Cooling DrivAer, including aerodynamic force measurements, detailed surface pressure measurements and flow field measurements at 3 cross-sections in the vicinity of the model. In addition, the paper will discuss the sensitivity of the experimental data to wind tunnel repeatability and facility-to-facility variations.
Journal Article

Analysis of Formaldehyde Scavenger and Its Reaction Products in POM Using Mass Spectrometry

2021-04-06
2021-01-0360
To meet the indoor air quality guideline of newly manufactured vehicles in Korea, China, and other countries, low formaldehyde grade POM (Polyoxymethylene) is used for interior parts essentially. In this paper, formaldehyde scavengers from of 2 commercial low formaldehyde grade POM pellets were identified by LC-MS (Liquid chromatograph-Mass spectrometer) as sebacic dihydrazide and dodecanedioic dihydrazide respectively. The reaction products between formaldehyde and formaldehyde scavengers were also detected, which were converted from hydrazide to hydrazone. So, this kind of additive would be gradually consumed by repetitive molding process or exposure to heat according to formaldehyde emission increase. We are expecting to apply this analytical method and result for quality control and benchmark of low formaldehyde grade POM.
Technical Paper

Concept Study on Windshield Actuation for Active Control of Wind Noise in a Passenger Car

2020-09-30
2020-01-1535
The windshield is an integral part of almost every modern passenger car. Combined with current developments in the automotive industry such as electrification and the integration of lightweight material systems, the reduction of interior noise caused by stochastic and transient wind excitation is deemed to be an increasing challenge for future NVH measures. Active control systems have proven to be a viable alternative compared to traditional passive NVH measures in different areas. However, for windshield actuation there are neither comparative studies nor actually established actuation concepts available to the automotive industry. This paper illustrates a comparative conceptual study on windshield actuation for the active control of wind noise in a passenger car. Making use of an experimental modal analysis of the windshield installed in a medium-sized vehicle, a reduced order numerical simulation model is derived.
Technical Paper

Appropriate Damping Loss Factor of Vehicle Interior Cavity for Valid Application of Statistical Energy Analysis

2020-09-30
2020-01-1524
It is known that SEA is a rapid and simple methodology for analyzing complex vibroacoustic systems. However, the SEA principle is not always valid and one has to be careful about the physical conditions at which the SEA principle is acceptable. In this study, the appropriate damping loss factor of the vehicle interior cavity is studied in the viewpoint of the modal overlap factor of the cavity and the decay per mean free path (DMFP) of the cavity. Virtual SEA tests are performed with an FE model combination, which is suggested by a previous study of Stelzer et al. for the simulation of the sound transmission loss (STL) of vehicle panel structure. The FE model combination is consisting of the body in white (BIW), an acoustical-excited hemisphere-shaped exterior cavity, and the interior cavity. It is found that the DMFP of the interior cavity is appropriate between 0.5 ~ 1 dB for applying SEA principle.
Technical Paper

Development, System Integration and Experimental Investigation of an Active HVAC Noise Control System for a Passenger Car

2020-09-30
2020-01-1538
Current developments in the automotive industry such as electrification and consistent lightweight construction increasingly enable the application of active control systems for the further reduction of noise in vehicles. As different stochastic noise sources such as rolling and wind noise as well as noise radiated by the ventilation system are becoming more noticeable and as passive measures for NVH optimization tend to be heavy and construction-space intensive, current research activities focus on active reduction of noise caused by the latter mentioned sources. This paper illustrates the development, implementation and experimental investigation of an active noise control system integrated into the ventilation duct system of a passenger car.
Journal Article

Reinforcement of Low-Frequency Sound by Using a Panel Speaker Attached to the Roof Panel of a Passenger Car

2020-09-30
2020-01-1570
The woofer in a car should be large to cover the low frequencies, so it is heavy and needs an ample space to be installed in a passenger car. The geometry of the woofer should conform to the limited available space and layout in general. In many cases, the passengers feel that the low-frequency contents are not satisfactory although the speaker specification covers the low frequencies. In this work, a thin panel is installed between the roof liner and the roof panel, and it is used as the woofer. The vibration field is controlled by many small actuators to create the speaker and baffle zones to avoid the sound distortion due to the modal interaction. The generation of speaker and baffle zones follows the inverse vibro-acoustic rendering technique. In the actual implementation, a thin acrylic plate of 0.53x0.2 m2 is used as the radiator panel, and the control actuator array is composed of 16 moving-coil actuators.
Journal Article

Robust Development of Electric Powertrain NVH for Compact Electric SUV

2020-09-30
2020-01-1503
Electric vehicles (EV’s) present new challenges to achieving the required noise, vibration & harshness performance (NVH) compared with conventional vehicles. Specifically, high-frequency noise and unexpected noise phenomenon, previously masked by the internal combustion engine can cause annoyance in an EV. Electric motor (E-motor) whine noise caused by electromagnetic excitation during E-motor operation is caused by torque ripple and radial excitation. Under high speed and high load operating conditions, the overall sound level may be low, however high frequency whine noise can impair the vehicle level NVH performance. An example of a previously masked unexpected noise phenomenon is a droning noise that can be caused by manufacturing quality variation of the spline coupling between the rotor shaft of the E-motor and the input shaft of the reducer. It is dominated by multiple higher orders of the E-motor rotation frequency.
Journal Article

Development of Logistic Regression Models to Classify Seat Fit

2020-04-14
2020-01-0869
The digital evaluation process of vehicle-seat dimensions is an efficient and cost-effective way to achieve better seating comfort and proper fit. The present study is intended to quantify the statistical relationships between seat dimensions (e.g., insert width and bolster height defined at SAE J2732) and subjective seat fit (e.g., too tight, right fit, or too wide). Subjective fit evaluations for 45 different vehicle seats and the corresponding vehicle seat dimensions at various cross-sectional planes were collected by seat engineers (experts). The best subset logistic regression analyses were applied to quantify the relationships between the collected expert evaluations and seat dimensions at each cross-sectional plane. As a result, significant seat dimensions on the seat fit were identified and their statistical relationships were quantified as regression coefficients.
Technical Paper

Pre-Validation Method of Steering System by Using Hybrid Simulation

2020-04-14
2020-01-0645
In this study, the preliminary validation method of the steering system is constructed and the objective is to satisfy the target performance in the conceptual design stage for minimizing the problems after the detailed design. The first consideration about steering system is how to extract the reliable steering effort for parking. The tire model commonly used in MBD(Multi-Body Dynamics) has limited ability to represent deformations under heavy loads. Therefore, it is necessary to study adequate tire model to simulate the behavior due to the large deformation and friction between the ground and the tire. The two approaches related with F tire model and mathematical model are used. The second is how to extract each link’s load in the conceptual design stage. Until now, each link’s load could be derived only by actual vehicle test, and a durability analysis was performed using only pre-settled RIG test conditions.
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