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As the original engine sound is usually not enough to satisfy the driver’s desire for a sporty and fascinating sound, Active Noise Control (ANC) and Active Sound Design (ASD) have been great technologies in automobiles for a long time. However, these technologies which enhance the sound of vehicles using loud speakers or electromagnetic actuators etc. lead to the increase of cost and weight due to the use of external amplifiers or actuators. This paper presents a new technology for generating a target sound by the active control of a permanent magnet synchronous motor (PMSM) of a mass-production steering system. The existing steering hardware or motor is not changed, but only additional software is added. Firstly, an algorithm of this technology, called Active Sound Generation (ASG), is introduced which is compiled and included in the ECU target code. Then the high frequency noise issue and its countermeasures are presented.

A new approach to achieve better customer perception of overall vehicle quietness is the sound balance improvement of vehicle interior sound during driving. Interior sound is classified into 3 primary sound source shares such as engine sound relative to revolution speed, tire road noise and wind noise relative to vehicle speed. Each interior sound shares are classified using the synchronous time-domain averaging method. The sound related to revolution order of engine and auxiliaries is considered as engine sound share, tire road noise and wind noise shares are extracted by multiple coherent output power analysis. Sound balance analysis focuses on improving the relative difference in interior sound share level between the 3 primary sound sources. Virtual sound simulator which is able to represent various driving conditions and able to adjust imaginary sound share is built for several vehicles in same compact segment.

Air conditioning is defined as the process of treating air so as to control simultaneously its temperature, humidity, cleanliness and distribution to meet the requirements of the conditioned space. As in the definition, the important actions involved in the operation of an air conditioning system are temperature and humidity control, air purification and movement. For these conditions this paper proposes a Automatic Climate Control(ACC) system of the bus. The system has cooling, heating, and dehumidifying modes, and is governed by dual 8-bit microprocessors. These modes are broken down into sub-modules dealing with control of the compressor, blower speed, damper position, air purifier, ventilators, preheater, air mixing damper and so on.

The purpose of this paper is to identify and reduce the suspension rattle noise. First, the characteristics of the rattle noise are analyzed experimentally in the time and frequency domain. It was found that the rattle noise and vibration at shock absorber mounting point are strongly correlated. Second, the sensitivity analysis of design parameters is performed using a half car model in ADAMS. The result of the simulation model is verified by comparison with test. Finally, the influence of design parameters for the rattle noise is investigated. The study shows that the shock absorber mounting bushing is the most sensitive parameter to affect the suspension rattle noise. This paper shows how the suspension rattle noise can be improved.

Due to technological evolutions and social demands, motor vehicles are requested to be enhanced in terms of occupant safety and comfort. As a result, many countries are reinforcing crash regulations and new car assessment programs. Automotive seats are essential parts for providing passenger safety and comfort and have become most important. Many automotive companies concentrate on optimization of the seat structure. This paper presents an overview of the recent evolution of the seat structures and gives a development procedure covering seat frame design, optimization and validation. Through the study, a competitive frame design is drawn as a case result and a design guideline and a standard development procedure is established

Acoustics comfort is a key point for the ground transportation market and in particular in the automotive area. A significant contributor to the noise levels in the cabin in the range 200Hz to 3000Hz is the HVAC (Heating, Ventilating, and Air Conditioning) system, consisting of sub-systems such as the air intake duct, thermal mixing unit, blower, ducts, and outlet vents. The noise produced by an HVAC system is mainly due to aeroacoustics mechanisms related to the flow fluctuations induced by the blower rotation. The structure borne noise related to the surface induced vibrations and to the noise transmission through the dash or plastic panels may also contribute but is not considered in this study. This study presents a digital approach for HVAC aeroacoustics noise predictions related to the ducts and outlet vents. In order to validate the numerical method flow and acoustics measurements are performed on production HVAC systems placed in an anechoic room.

This paper reflects an efficient and comprehensive approach for vehicle sound optimization integrated into the entire development process. It shows the benefits of early consideration of typical vehicle NVH features and of intensive interaction of P/T and vehicle responsibilities. The process presented here considers the typical restriction that acoustically representative prototypes of engines and vehicles are not available simultaneously at the early development phase. For process optimization at this stage, a method for vehicle interior noise estimation is developed, which bases on measurements from the P/T test bench only, while the vehicle transfer behavior for airborne and structure-borne noise is assumed to be similar to a favorable existing vehicle. This method enables to start with the pre- optimization of the pure P/T and its components by focusing on such approaches which are mainly relevant for the vehicle interior noise.

Faced with the challenge to improve vehicle quality and reduce the development cycle for new product, experimental and/or analytical approach have been used to assure improvements in vehicle NVH performance. Prediction of dynamic characteristics is the most important factor to shorten development time. In order to predict car interior noise at the pre-design stage, a total vehicle without chassis parts and its cavity are fully modeled by finite elements. To reduce FE model generation time and get more effective design modification index, hybrid model combining FE data and experimental data is used. In this paper, the hybrid modeling based on FBS technique is used for identifying substructure contribution and modification. Driving force is also acquired by powertrain test. To verify this model, a passenger car is tested and compared with analysis data.

This paper presents an in-vehicle information system, AVICS in development. With AVICS, the driver could get the various information on traffic, news, weather, restaurants, and so on, which the AVICS information center provides via mobile telecommunication network. The driver requests the information to operator in center by voice with hands-free system or by handling the menu offered in the form of web-page. The in-vehicle unit for AVICS is designed to interface with wireless network with a built-in RF MODEM, to control NAVI system, and to display the information on the LCD monitor of AV system. The Internet browser is customized to parse specific HTML tags, application software is realized on 32-bit RISC processor. In this paper, we will overview the concept of AVICS and focus on development of in-vehicle unit of AVICS.

Voice Recognition (VR) systems have become an integral part of the infotainment systems in the current automotive industry. However, its recognition rate is impacted by external factors such as vehicle cabin noise, road noise, and internal factors which are a function of the voice engine in the system itself. This paper analyzes the VR performance under the effect of two external factors, vehicle cabin noise and the speakers’ speech patterns based on gender. It also compares performance of mid-level sedans from different manufacturers.

Brake grinding noise is caused by the friction of the disc and pads. The friction generates vibration and it transmits to the body via the chassis system. We called it structure-borne noise. To improve the noise in the vehicle development, the aspects of chassis or body's countermeasure occurs many problems, cost and time. In this reason many brake companies try to make solution with brake system, like brake pad materials or disc surface condition. However the countermeasures of excitation systems also have a lot of risk. It could be occurred side-effects of braking performance, and need to re-verify brake noise like Creep-groan, Groan, Squeal, Judder and so on. For this reason, it is essential to make a robust chassis system in the initial development stage of the vehicle for the most desirable grinding noise-resistant vehicle. This paper is about rear brake grind noise path analysis and countermeasure of chassis system. There are two steps to analysis.

A comprehensive investigation was carried out in order to develop the idle sound quality for diesel V6 engine when the engine development process is applied to power-train system, which included new 8-speed automatic transmission for breaking down the noise contribution between the mechanical excitation and the combustion excitation. First of all, the improvement of dynamic characteristic can be achieved during the early stages of the engine development process using experimental modal analysis (EMA) & the robust design of each engine functional system. In addition, the engine structural attenuation (SA) is enhanced such that the radiated combustion noise of the engine can be maintained at a target level even with an increased combustion excitation. It was found that the engine system has better parts and worse parts in frequency range throughout the SA analysis. It is important that weak points in the system should be optimized.

The squeak noise generated during the moving of the door glass has a influence on the performance of vehicles felt by the consumer. In order to improve the noise, it is necessary to understand the principle of a friction vibration. In this paper, it is confirmed that the principle on the waist belt is most closely related to stick-slip and sprag-slip among various vibration characteristics. Stick-slip is expressed by energy accumulation and divergence due to difference in static and dynamic friction coefficient. Sprag-slip define instability of geometric structure due to angle of lips on the belt. In this paper, the physical model and the energy equation are established for the above two phenomena. Stick-slip can be solved by decreasing the difference of the static and dynamic friction coefficient. Sprag-slip is caused by the ratio of compressive and shear stiffness of the lips. The belt uses flocking to ensure durability, not coating.

Engine calibration on the powertrain test bed with transient mode is proposed with dynamic powertrain test bed having low inertia dynamometer. Automated ECU (Engine Control Unit) calibration system is completed with the combination of experimental design software, powertrain test bed, evaluation tools and their electrical interfaces. The process is composed up of the system interface definition, test design using DoE skill, test proceedings by step sequence of connecting systems, measured data collecting, mathematical model and optimization result extraction at the end. All the processes are automated by interfaces between the systems. Acceleration surge is minimized by proposed process by optimizing combustion control labels and tip in driveability is maximized by manipulating torque filter labels of EMS (Engine Management System) logic. Their detailed steps from the problem definition to the verification test results of improved design with vehicle test are presented.

It is common knowledge that body structure is an important factor of road noise performance. Thus, a high stiffness of body system is required, and determining their optimized stiffness and structure is necessary. Therefore, a method for improving body stiffness and validating the relationship between stiffness and road noise through CAE and experimental trials was tested. Furthermore, a guideline for optimizing body structure for road noise performance was suggested.

In order to achieve the proper automobile interior sound, the tailpipe noise of the exhaust system must be considered as a main contributor. This paper describes a study of the achievement of dynamic sound quality through exhaust system design. Firstly, we determined the vehicle's interior sound quality and established a target sound using a subjective assessment of 10 benchmark vehicles. The exhaust noise target is determined by means of transfer path analysis focusing on the noise source and how it's impacted by the muffler design. The exhaust system is commonly modeled as a combination of source strength and impedance. We obtained the source character by the wave decomposition method using two microphones and six loads ultimately leading to an optimized design of the inner muffler structure. Based on this study, we achieved dynamic interior sound and improved exhaust system performance.

Fluctuation in the sound pressure level of the interior noise of an on-road vehicle is always caused by unpredictable factors such as wind gusts, traffic, roadside obstacles, and changing drive-by-drive conditions, and is hence, not reproducible in nature. Since the human brain is known to be more sensitive to noise that is amplitude-modulated than noise at a steady level [1], it is important to evaluate and improve the NVH performance of a vehicle in terms of the fluctuating interior noise likely to be experienced by drivers or users. To this end, an evaluation system was developed as part of this study, the details of which are presented in this paper. The system is composed of hardware for database storage and replay of sounds, and software for synthesizing the noise signals. For given wind tunnel test results, the evaluation system yields a wind noise model that can synthesize wind noise signals for any wind scenario.

This paper describes a systematic approach to the development of a luxurious driving sound. In the first step, the luxurious sound is conceptualized through jury test, factor analysis and regression analysis. From the results, the main factors and the correlation equation for the luxurious sound are extracted. Also, customer's preference for the luxurious sound is investigated from the customer clinic. In the second step, three core axes and the detailed indices for luxurious sound are defined and quantified. These core axes are a dynamic sound character, a sound balance and a sound harmony. These core axes are also composed of detailed indices and quantified by guide lines. In the third step, each contribution of the sub-systems for sound quality is identified and the target values and methods for implementing the luxurious sound are suggested. In this process, noise path analysis and the customer's preference in each region are considered.

The paper describes an engineering project carried out to optimize the crashworthiness of an existing passenger car for frontal crash using a procedure relying on numerical simulation. An optimization target is defined in terms of an ideal acceleration pulse at the seats anchors. The acceleration time history and structural members are scanned in parallel to correlate the local acceleration peaks to specific structural members. Members details are iteratively modified in order to alter the accelerations and get closer to the target.