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Development of the Defrost Performance Evaluation Technology in Automotive using Design Optimization Analysis Method

Hyundai Mobis-Hyeonseok Seo, Jinwon Seo, Bongkeun Choi
  • Technical Paper
  • 2020-01-0155
To be published on 2020-04-14 by SAE International in United States
In this study, we developed the defrost performance evaluation technology using the multi-objective optimization method based on the CFD. The defrosting is one of the key factors to ensure the drivers’ safety using the forced flow having proper temperature from HVAC during drive. There are many factors affecting the defrost performance, but the configurations of guide-vane and discharge angles in the center DEF duct section which are main design factors of the defrost performance in automotive, so these were set to the design parameters for this study. For the shape-optimization study, the discharge mass flow rate from the HVAC which is transferred to the windshield and the discharge areas in the center DEF duct were set to the response parameters. And then, the standard deviation value of mass flow rate on the selected discharge areas checking the uniformity of discharge flow was set to the objective function to find the optimal design. The results on the windshield from optimization analysis were quantified from some kind of standards to evaluate the defrost performance, in particular, the…
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Development of CFD Program for Automotive Ventilation and Defrost Simulation using OpenFOAM

Hyundai Mobis-Jinwon Seo, Hyeonseok Seo, Bongkeun Choi
  • Technical Paper
  • 2020-01-0154
To be published on 2020-04-14 by SAE International in United States
Numerical simulations are used to predict performance in the automotive development process. In particular, ventilation and defrost performances of automotive HVAC system are developing according to design variables and environmental conditions based on computational fluid dynamics (CFD). Recently, computer hardware performance and analysis technology are improved and the proportion of simulation is increasing accordingly. However, cost of software license also increases in these development environments. In this paper, we developed CFD program(GUI) with OpenFOAM to analysis automotive ventilation and defrost. This program includes improved turbulent model and the fluid film model for ventilation and defrost analysis that don’t support in the open library.
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Passenger Injury Analysis Considering Vehicle Crash after AEB Activation

Hyundai Mobis-Seokhoon Ko, Garam Jeong, Dohyung Kim, Haekwon Park, Kyusang Lee, Raeick Jang
  • Technical Paper
  • 2019-22-0023
Published 2020-03-31 by The Stapp Association in United States
Owing to an increasing autonomous emergency braking (AEB) adoption, emergency braking before crash occurs more often than in the case of conventional vehicles. Due to the sudden deceleration in AEB activation, passengers move forward before the crash. To explore how this forward movement affects passenger injury, sled tests are performed with an inclined dummy representing forward displacement. The test shows that a shorter distance between the airbag and passenger results in bigger neck injuries induced by airbag deployment force. A countermeasure is suggested to prevent neck injury in emergency braking situation by reducing deployment force and protrusion.
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Efficient Method for Head-Up Display Image Compensation by Using Pre-Warping

Hyundai Mobis-Mijin Jeon, Youna Lee
Hyundai Motor Group-Iksoon Lim
Published 2019-04-02 by SAE International in United States
A Head-Up Display (HUD) is electrical device that provides virtual images in front of driver. Virtual images are consists of various driving information. Because HUD uses optical system there exist image distortions with respect to image height and driver’s eye position. Image warping is image correction method that makes a geometrical change on image to minimize image distortions. In this paper to minimize image distortions, we use optical data driven warping matrix for each image height. But even though we applied data driven warping matrix, image distortions occur due to assemble and manufacturing tolerances when HUD is built. In this paper, we also suggest pre-warping method to minimize image distortions considering tolerances. We simulated 3 compensation functions to get rid of image distortions from the tolerances. By using proposed pre-warping method we could reduce maximum x, y distance by 31.5%, 39% and average distance by 32.2%, 27.9% of distortions.
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Improvement of Steering Performance Using Steering Rack Force Control

Hyundai Mobis-Byoungyun Lee
Hyundai Motor Company-Chanjung Kim, Dayul Son
Published 2019-04-02 by SAE International in United States
Drivers continually require steering performance improvement, particularly in the area of feedback from the road. In this study, we develop a new electrically-assisted steering logic by 1) analyzing existing steering systems to determine key factors, 2) modeling an ideal steering system from which to obtain a desirable driver torque, 3) developing a rack force observer to faithfully represent road information and 4) building a feedback compensator to track the tuned torque. In general, the estimator uses the driver torque, assist torque and other steering system signals. However, the friction of the steering system is difficult to estimate accurately. At high speed, where steering feeling is very important, greater friction results in increased error. In order to solve this problem, we design two estimators generated from a vehicle model and a steering system model. The observer that uses two estimators can reflect various operating conditions by using the strengths of each method. Therefore, it reflects the driving situation more precisely. We evaluated real vehicle performance under various operating conditions to compare the actual rack force and…
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A Study on Improvement of Optical/Electrical Properties of Indium-Tin-Oxide Thin Films Prepared by Sol-Gel Process

Hyundai Mobis-Deukkyu Hwang, Seungwoo Shin, Hyeondon Kim
Gachon University-Taeil Lee
Published 2019-04-02 by SAE International in United States
Ar plasma treatment was carried out to reduce the sheet resistance of indium tin oxide (ITO) thin films. To verify how the concentration of oxygen vacancies in the film increased with the Ar plasma treatment time, cumulative and continuous plasma treatments were conducted. In addition, to improve the transmittance and reduced the sheet resistance the PDMS layer was as a stamp on the surface of ITO. The oxidation of the PDMS stamp appears to be a key factor to improve the characteristics of ITO thin film. Furthermore, an indium-tin-oxide (ITO) thin film with approximately 50 nm thickness was successfully synthesized on glass substrates by using a fully aqueous sol-gel process. The annealing temperature and argon plasma treatment time appear to be key factors in reducing resistivity and increasing the transmittance of the thin film.
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Development of Hybrid Power Steering System for Commercial Vehicle

Hyundai Mobis-Byoungyun Lee
Published 2019-03-25 by SAE International in United States
Future technology trends of commercial vehicle steering components can be divided into three types. Environment-friendly technologies for environment-related regulations such as reducing emissions and improving fuel efficiency, and technology for driving convenience using electric steering control systems, and safety technology to protect drivers, passengers, nearby vehicles and pedestrians. Heavy duty commercial vehicles require a high-power steering system that used engine-driven hydraulic pump systems (generally used min 120bar, 17Liter/min) compared to passenger cars. In recent technical trend, In order to improve fuel efficiency and realize autonomous driving technology, we designed EHPS and Motor driven electric control actuator with the same structure as C-EPS.Unlike the HPS system, the power used in the EHPS system is the motor, which rotates the gear pump to generate flow and pressure, and the steering oil is delivered to the ball nut gearbox to operate the power steering system through the pitman arm. The advantage of EHPS is that it does not use the engine drive torque, so it improves fuel efficiency by about 1%, and when the pump is connected in…
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The Factors Governing Corrosion Stiction of Brake Friction Materials to a Gray Cast Iron Disc

Hyundai Mobis-Wangyu Lee, Dooyeon Kim, Keeyang Lee
Korea Univ.-Jaehyun Gweon, Sanghee Shin, Ho Jang
Published 2018-10-05 by SAE International in United States
Corrosion stiction at the contact interface between a brake friction material and a gray iron disc under the parking brake condition was investigated by evaluating the possible parameters that affect the shear force to detach the corroded interface. Using production brake friction materials, comprising non-steel and low-steel types, corrosion tests were carried out by pressing the brake pad onto the gray iron disc using a clamp at various conditions. Results showed that the shear force to detach the corroded interface tended to increase with applied pressure and corrosion time. On the other hand, porosity, acidity, and hydrophobicity of the friction material did not show a reliable correlation to the stiction force. The poor correlation of the stiction force with the friction material properties indicated that the stiction force was not determined by a single factor but governed by multiple parameters including surface contact areas and inhomogeneity of the ingredients. Microscopic observation of the detached disc surface showed adhered fragments that were removed from the friction material surface, thus shedding light on the possible estimation of…
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Disc Brake Squeal vs. Disc Pad Compressibility-Caliper Stiffness Interactions: Low-Frequency Squeal and High-Frequency Squeal vs. Differential Pad Wear

Hyundai Mobis-Wan Gyu Lee, Young sun Cho
KBautosys Co., Ltd.-Seongjoo Lee, JeSung Jeon, JooSeong Jeong, Byeongkyu Park, ShinWook Kim, ShinWan Kim, Seong Kwan Rhee
Published 2017-09-17 by SAE International in United States
It is widely believed or speculated that higher pad compressibility leads to reduced brake squeal and that caliper design can affect brake squeal. After encountering anecdotal contradictory cases, this investigation was undertaken to systematically generate basic data and clarify the beliefs or speculations. In order to adjust pad compressibility, it is common to modify pad molding temperatures, pressures and times, which in addition to changing the compressibility, changes friction coefficient and physical properties of the pad at the same time. In order to separate these two effects, NAO disc pads were prepared under the same molding conditions while using different thicknesses of the underlayer to achieve different compressibilities, thus changing the compressibility only without changing the friction coefficient and physical properties of the pad. Test results show brake squeal occurrences increasing with increasing compressibility and increasing damping, contrary to the common belief. A combination of higher compressibility pads and higher caliper stiffness leads to increased brake squeal occurrences. The inner pad and outer pad wear rate difference affects disc squeal or caliper-knuckle assembly squeal generation.…
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Optimal Design of EPB Caliper Using DOE

Hyundai Mobis-Sangbum Kim, Jae Seung Cheon, Inuk Park, Yongsik kwon
Published 2017-09-17 by SAE International in United States
An Electrical Parking Brake (EPB) system is a device that operates to park the vehicle automatically with the push of a button instead of using conventional hand or foot levers which in some ways makes it the first by wire type of brake system. As such, it is being considered in some vehicle architectures as an automatic redundant backup for vacuum-less brake systems or autonomous cars.The EPB system is generally divided into cable puller and motor on caliper (MOC) types. Recently, the MOC type EPB is being more widely applied in the global market due to product competitiveness and cost effectiveness. The MOC type EPB is composed of the caliper body, torque member, pad assembly, nut assembly and actuator. Among them, the caliper body and torque member play a main role in the robustness of the EPB system and occupy more than 80% of the total weight. Therefore, optimal design of the caliper body and torque member to maximize stiffness while minimizing weight is systematically important in the design of an EPB system.In this paper,…
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