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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.

CO2 emission is more serious in recent years and automobile manufacturers are interested in developing technologies to reduce CO2 emissions. Among various environmental-technologies, the use of solar roof as an electric energy source has been studied extensively. For example, in order to reduce the cabin ambient temperature, automotive manufacturers offer the option of mounting a solar cell on the roof of the vehicle [1]. In this paper, we introduce the semi-transparent solar cell mounted on a curved roof glass and we propose a solar energy management system to efficiently integrate the electricity generated from the solar roof into internal combustion engine (ICE) vehicles. In order to achieve a high efficiency solar system in different driving, we improve the usable power other than peak power of solar roof. Peak power or rated power is measured power (W) in standard test condition (@ 25°C, light intensity of 1000W/m2(=1Sun)).

Pressure variation during engine combustion generates torque fluctuation that is delivered through the driveline. Torque fluctuation delivered to the tire shakes the vehicle body and causes the body components to vibrate, resulting in booming noise. HKMC (Hyundai Kia Motor Company)’s TMED (Transmission Mounted Electric Device) type generates booming noises due to increased weight from the addition of customized hybrid parts and the absence of a torque converter. Some of the improvements needed to overcome this weakness include reducing the torsion-damper stiffness, adding dynamic dampers, and moving the operation point of the engine from the optimized point. These modifications have some potential negative impacts such as increased cost and sacrificed fuel economy. Here, we introduce a method of reducing lock-up booming noise in an HEV at low engine speed.

High-voltage battery system plays a critical role in eco-friendly vehicles due to its effect on the cost and the electric driving range of eco-friendly vehicles. In order to secure the customer pool and the competitiveness of eco-vehicle technology, vehicle electrification requires lowering the battery cost and satisfying the customer needs when driving the vehicles in the real roads, for example, maximizing powers for fun drive, increasing battery capacities for achieving appropriate trip distances, etc. Because these vehicle specifications have a critical effect on the high-voltage battery specification, the key technology of the vehicle electrification is the appropriate decision on the specification of the high-voltage battery system, such as battery capacity and power. These factors affect the size of battery system and vehicle under floor design and also the profitability of the eco-friendly vehicles.

Passenger fatigue during long distance driving is greatly influenced by the comfort performance of the seat. Seat comfort performance is determined by the appropriate contour of the seat and the appropriate pad with sufficient thickness. The height of vehicle has been lowered to enhance car styling, and battery for electric vehicle applied to the underbody of the vehicle, reducing the package space of the seat in the vehicle. These external factors eventually lead to a reduced pad thickness of the seat cushion and compromise one of the important components in the seat cushion compartment, creating an uncomfortable cushioning problem when driving long distances. To improve the cushion composition of the seat within a limited package, air bladders are applied to the underside of the cushion pad. In addition, the function to support the buttocks using the air bladders of the lower cushion, similar to lumbar support for the back, was implemented to improve cushion comfort performance.

In order to understand the automotive PEM fuel cell system, mathematical system modeling is conducted and the model is implemented and simulated by using the Matlab®/Simulink®. The components such as fuel cell stack, air supplier, and radiator are modeled individually and integrated into a system level. The PEM fuel cell system operation control includes thermal management, air supply control, hydrogen supply control, fuel cell stack protection control, and load following control. In the thermal management, the inlet and outlet temperature of coolant are controlled to operate the fuel cell stack in desired temperature range and to prevent flooding inside the fuel cell stack. In air supply control and hydrogen supply control, the flow rates of air and hydrogen are controlled not to starve the fuel cell stack according to the output current. A control structure for the system is developed and confirmed by using the developed simulation model.

This paper mainly focuses on a lateral control law for pre-given path following which is developed by using the backstepping control design methodology. The position information of the vehicle is obtained by Real Time Kinematic DGPS, and the yaw rate and side-slip angle used in controller are estimated by Kalman estimator. To show the performance of the proposed controller under different speed and various path curvature conditions, the results are given through experiments which are executed on proving ground especially designed for high maneuvering test of which minimum radius of curvature is about 60 m.

The use of light-weight materials in automotive engine components has increased in order to achieve better fuel efficiency and engine performance. In this study, Al alloy (AI5056) valve spring retainer can reduce a weight by 63% in comparison to steel and improve the upper limit of engine speed by about 500rpm. The Al valve spring retainer was fabricated by cold forging and coated with hard anodizing, DLC (diamond like coating), cold spray and thermal spray for better wear resistance and durability. We conclude that among these materials the DLC coating improves the wear resistance of Al valve spring retainer and has a sufficient durability after endurance testing.

All vehicles have some or all accessories such as alternators, air conditioner compressors, power steering pumps, and water pumps. These devices are mounted on the front of the engine and are powered by a pulley mounted on the front of the crankshaft. This power represents a parasitic loss and this loss is greater at higher engine speeds. To reduce the impact of the accessories on the engine, a two speed transmission that reduces the accessories speed at off-idle conditions was designed, implemented, and tested on several vehicles. The vehicles were tested for fuel economy on the Japanese 10.15 Mode driving cycle, the FTP75 city cycle, and the HWFET Highway Cycle. Results showed an average of 5% reduction in fuel consumption and a corresponding 5% in CO2 with no impact of accessory performance and vehicle drivability. Simulations with GT-Drive software was used to determine the optimum speed reduction and the threshold switching speed that maximizes fuel savings.

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.

This paper describes an automated path following system using vision sensor. Lateral control law for path following is especially underlined which is developed by using the backstepping control design methodology. To establish the proposed control system, the lateral offset to the reference path, the heading angle of vehicle relative to tangent line to the path, and path curvature are required. Those inputs to the controller have been calculated through Kalman filter which is frequently adopted for the purpose. The lane mark detection has been achieved in an ECU (Electric Control Unit) platform with vision sensor. The yaw rate and side-slip angle also needed in the controller are estimated by Kalman estimator. To show the performance of the proposed controller under different speeds, experiment has been conducted on a proving ground having straight and curve sections with the curvature of about 260m.

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.

For a complete automotive HVAC system, it is desirable to keep good air quality control for the interior vehicle cabin. This experimental study for evaluating the CO2 concentration levels in a vehicle cabin was done on the roads in South Korea. Increasing levels of CO2 can cause a passenger to become tired, sleepy and cause headaches or discomfort. The study results shows that CO2 and fine dust concentration is a result of the number of passengers,_driving condition and HVAC user settings. The result from this investigation can be used to establish a development guide for air quality in a vehicle cabin.

Parallel Hybrid Electric Vehicle consists of internal combustion engine, engine clutch, motor, automatic transmission, Integrated Starter Generator (ISG), and battery. Due to hybridizations such as using engine clutch to disengage the internal combustion engine and omitting torque converter from the automatic transmission to increase fuel economy, drivability will not be same as conventional vehicle. To ensure drivability comparable to conventional vehicle, dynamic simulation has been utilized to foresee the drivability issues for the proposed hybrid system and ideas for improvements are tested in simulation. CoSimulation of AMESim vehicle model and Simulink Hybrid Control Unit (HCU) model has been used to test and improve HCU logic.

Accelerated simulation of vehicle corrosion in a controlled environment not only involves large chambers for actual vehicle tests, but also requires careful consideration of interactions between various parameters given a short time period within which the test is bounded. A new corrosion durability test mode reproducing various field conditions using salt spray, climatic, sunlight simulation and cold chambers has been developed. Verification of the test mode is carried out using four actual vehicle corrosion tests correlated against used cars of Nort h America and Northern Europe. The process of new corrosion test mode is discussed along with the characteristics of the test chambers.

With the advent of cars with computerized engines, drivers sometimes suffer discomfort with “check engine” light problem, and as a result, insist on increasing levels of reliability in their cars. Hence, reliability of the wiring harness has become a very important automotive design characteristic. On one hand, the more secure an engine mounting system is, the more stable the engine wiring harness is. In order to enhance their durability, car manufacturers need to perform many validation tests during the development phase which involves a lot of time and cost. In this study, a newly developed lab-simulation test is proposed to qualify the design of engine mounting and engine wiring early in the design cycle and reduce time and expense. The lab-simulation test has contributed to a significant cost and time reduction and has shown good correlation to the original proving ground test.

Recently, high speed direct injection (HSDI) diesel engines are rapidly expanding their application to passenger cars and light duty commercial vehicles in western European market and other countries such as Korea and Japan. These movements are strongly backed by the technological innovations in the area of air charging and high pressure fuel injection systems. Variable geometry turbine (VGT) turbocharger, which could overcome the typical weak point of the existing turbocharged engine, and the common rail fuel injection system, which extended the flexibility of fuel injection capability, became two of the most frequently referred keywords in recent HSDI technology. In this paper some aspects of VGT potential as a full load torque and power modulator will be discussed. Possibility to utilize the portion of full load potential in favor of part load emissions and fuel economy will be investigated.

A systematic process of optimization is suggested to obtain the best control maps for a parallel type hybrid electric vehicle. Taking the fuel consumption as the cost function and driving cycle as part of the constraints, an optimization problem for CVT pulley ratio control and motor torque control can be formulated. The change of the battery charge state between the start and end point of the given driving cycle also works as a constraint. In order to see the effect of various control strategies on system behavior and overall fuel consumption, a simulation model was built to accommodate the functional blocks representing hybrid powertrain subsystem components and corresponding control units.

The topology optimization made a great success in pure structural design in an actual industrial field. However, a lot of factors interact each other in a actual engineering field in highly complicated manner. The typical conceptual trade-off is that cost and performance, that is, since they are competing factors, one can't improve the specific system without consideration of interaction. The vehicle has lots of competing factors, especially like fuel economy and acceleration performance, mass and stiffness, roominess and cost, short front overhang and crash-worthiness and so on. In addition, they interact each other in a more complicated manner, that is, fuel economy has something to do with not only engine performance but also mass, roominess, stiffness, the length of overhang, trunk volume, etc. So, most of decision-makings have been made by management based on subjective knowledge and experience.

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.