Display:

Results

Viewing 1 to 30 of 7358
2015-04-14
Technical Paper
2015-01-0661
Jianwang Shao, Xian Wu, Na Wei, Ding Wang, Guoming Deng, Ming Xu
An increasing demand for vehicle noise control has been proposed and at the same time, vehicle weight and fuel economy have become critical for the automotive industry. The methodology of statistical energy analysis (SEA) is used to balance both light weight and high noise insulation performance. In this paper, the vehicle dash and floor sound package systems, which are two of the major paths for vehicle interior noise, are studied and optimized by CAE and testing technology. Two types of sound package which are the conventional insulation system and the lightweight one are chosen for the vehicle dash and floor system. The vehicle dash and floor systems are modeled by SEA and the transmission loss (TL) of the dash and floor system is analyzed, respectively. Several influence factors of the TL are also analyzed, such as sound package coverage, the leaks, etc.
2015-04-14
Technical Paper
2015-01-0216
Ping-Min Hsu, Ming Hung Li, Kuo-Ching Chang
This paper studies noise filtering in an autonomous emergency braking (AEB) system with a sensor fusion between a millimeter wave (MMW) radar and a camera. The AEB system may automatically brake cars by mistake due to the sudden appearance of noise signal if it does not involve any noise filtering mechanism for the object sensor. This may cause some accidents. To avoid such accidents, we propose the filters for three kinds of noise—named as twice harmonic noise, ground noise, and specular refection noise—which are commonly suffered while applying MMW radars. The former is caused by the reflection of a radar wave between a target object and the MMW radar. Based on the concern that the MMW radar evaluates the sensing distance based on the time interval between the transmitting and receiving of the radar wave, one of the sensing distances would be twice as longer as one of others due to the wave reflection. The object featuring this characteristic is further filtered.
2015-04-14
Technical Paper
2015-01-0235
Shiv Shankar Prasad, Jahangir Mansoori, Jin Seo Park
A vehicle horn is a sound-making device used to warn others of the approach of the vehicle or of its presence. Some countries require horns by law. Conventional Horns are electromechanical with steel diaphragm and electromagnet acting upon it. Switching of horn is performed by mechanical contact breaker assembly that repeatedly interrupts the current to the electromagnetic. Up-Down Movement of diaphragm with response to the current creates a sound wave across the horn. Conventional Horn faces the problem of wear and tear of mechanical contact and internal parts. Switching of contacts results in Arcing .There is no current and surge voltage protection for the coil of conventional horn. These problems of conventional system might be OK in the general markets. But in specific markets which are using horn frequently, these have to be considered as serious issues. Especially, horns are one of the most abusing parts of vehicle in India.
2015-04-14
Technical Paper
2015-01-0663
Ling Zheng, Zhanpeng Fang, Zhongcai Tang, Zhenfei Zhan, Jiang-hua Fu
The design optimization of vehicle body structure is addressed to reduce interior noise and improve customer satisfaction in this paper. The structural-acoustic model is established and the response of sound pressure in frequency domain is obtained by using finite element method. The minimization of sound pressure near the driver’s right ear depends on the geometry of vehicle body structure and the layout of damping treatments. The panel participation analysis is performed to find out the key panels as design variables and improve the efficiency of optimization computation. Response Surface Method (RSM) is utilized to optimize the vibro-acoustic properties of vehicle body structure instead of complex structural-acoustic coupling finite element model. Structural-acoustic problem is approximated by a series of quadratic polynomial using RSM. Geometric optimization problem of panels is described and solved to minimize the interior noise in vehicle.
2015-04-14
Technical Paper
2015-01-0831
Wonah Park, Youngchul Ra, Eric Kurtz, Werner Willems, Rolf D. Reitz
The low temperature combustion concept is very attractive for reducing NOx and soot emissions in diesel engines. However, it has potential limitations due to higher combustion noise and CO and HC emissions. A multiple injection strategy is an effective way to reduce unburned emissions and noise in LTC. In this paper, the effect of multiple injection strategies was investigated to reduce combustion noise and unburned emissions in LTC conditions. A hybrid surrogate fuel model was developed and validated, and was used to improve LTC predictions. Triple injection strategies were considered to find the role of each pulse and then optimized. The split ratio of the 1st and 2nd pulses fuel was found to determine the ignition delay. Increasing mass of the 1st pulse reduced unburned emissions and an increase of the 3rd pulse fuel amount reduced noise. It is concluded that the pulse split ratio can be used as a control factor for emissions and noise.
2015-04-14
Technical Paper
2015-01-0666
Chenguang Li, Fue-Sang Lien, Eugene Yee, Mike Dong
A deeper understanding of the complex phenomenology associated with the flow induced noise and vibration in a dynamic valve is of critical importance to the automotive industry. To this purpose, a two-dimensional axisymmetric numerical model has been developed to simulate the complex processes that are responsible for the noise and vibration in a poppet valve (or poppet). More specifically, an Eulerian multiphase flow model, a dynamic mesh and a user-defined function are utilized within the ANSYS-FLUENT software system in order to facilitate the modeling of the complicated two-phase fluid-structure interaction problem associated with the generation of noise and vibration in a poppet valve. In this strongly coupled simulation framework, the poppet valve which is driven by spring and various dynamical fluid forces (e.g., viscous and pressure forces), is modeled as an under-damped vibration system.
2015-04-14
Technical Paper
2015-01-1124
Gerrit Knabe, Markus Zahlten, Ferit Kücükay
In order to improve the acoustic comfort inside passenger cars in terms of transmission noise, a special method has been developed. For a structured and comprehensive analysis of the transmission noise, the generation and transfer mechanisms are divided into four separate but nevertheless connected parts. Although simulation and components tests are used to analyze vibration excitation which may cause rattle and the mechanisms causing rattle in detail, they are not the main part of the analysis. The focus of this study is on the transfer of automotive transmission rattle and the passengers’ perception. The noise characteristics, which can be specified using conventional analysis methods as well as assessments by test persons, are important for the transfer path of the disturbing noise. By combining different methods of transfer path analysis (TPA), direct airborne-sound transmission is identified as a significant transfer path of the rattling noise.
2015-04-14
Technical Paper
2015-01-1555
Charalampos Kounenis, David Sims-Williams, Robert Dominy, Arganthaël Berson, Nicholas Oettle, Claire Freeman
A road vehicle encounters unsteady flow conditions as it traverses through the stationary wakes of road side obstacles, but also as a result of turbulence in the natural wind and the unsteady wakes from other on-road vehicles. This work investigates aeroacoustic impacts of steady state and dynamic yaw. The later was simulated using the Pininfarina active Turbulence Generation System (TGS), a system designed to capture some of the effect of time-varying on-road conditions. The results presented are for a production vehicle. This work focusses in particular on investigating changes in noise sources, including through the use of beamforming techniques. Both interior beamforming (noise vision) and exterior beamforming were deployed. In the latter, the beamforming calculations were based on vehicle surface CAD data in order to obtain an enhanced result, in particular when the vehicle is physically yawed relative to the microphone array.
2015-04-14
Technical Paper
2015-01-1285
Dingfeng Deng, Fanghui Shi, Louis Begin, Isaac Du
Several instances have occurred where the outer surface of turbocharger fully floating journal bearing bushings have exhibited damage from oil debris resulting in loud constant tone noises and subsequent warranty claims. This paper studies the effect of oil debris in Turbocharger journal bearings on Subsynchronous NVH. A CFD model is built to study the behavior of oil debris particles with different sizes. The oil debris particles tend to navigate to the inner film or outer film of bearing bushing depending on the drag and centrifugal forces. It is found that the dominant centrifugal forces prevent larger particles from reaching the inner film while smaller particles travel more easily to the inner film. It is also found that the turbine side is more likely to become damaged from debris than the compressor side bearing due to higher temperatures. A tribology analysis is executed to determine the effect of oil debris particles on the speed ratio of the bearing bushing to the shaft.
2015-04-14
Technical Paper
2015-01-1665
Nicolas Arnault, Adrien Baudet, Nicolas Becker
Vehicle integration in today society and especially in urban zones is the one of the main focus of regulators as well as car manufacturers. Indeed, vehicles impact on everyday life as air quality, noise, traffic density, urban spaces occupied by parked cars, among others is scrutinized and leads to at least significant efforts, but often to major improvements on all those topics. Noise is one of the key nuisances from which the car is the source. There are already some existing regulations, and they intend to become stricter and stricter. The perfect example of this trend is the recent new European Commission regulation adopted in April 2014, which requires a fair reduction of the allowable emitted noise, but may also introduce performance labels. Of course, there are solutions to deal with noise emissions.
2015-04-14
Technical Paper
2015-01-1666
Lingzhi Li, Yimin Yang, Fengjun Zhao, Zhi Zhang, Hailong Cheng, Hangsheng Hou
An issue of engine squealing in low temperature range (around -25C) right after start-up emerged for a significant number of vehicles in a program. The squealing noise typically only lasted for a few seconds. The earlier effort had focused on typical common culprits such as the pulley-belt systems etc. However, much effort, by subjective listening, yielded no fruitful results for more than a year. The application of near-field acoustic holography on top of the engine in a climate chamber quickly identified several noise source locations. Further noise source identification on the top, front and left sides of the engine pinpointed the top three noise source locations: the idler pulley and the water pump on the front side, the air compressor on the right side, and the air intake throttle on the top. Then a series of experiments were conducted.
2015-04-14
Technical Paper
2015-01-1668
Chetankumar Patel, Nachiketa Tiwari, Avinash Kumar Agarwal
High viscosity of vegetable oil causes problems while using them as alternate fuel for compression ignition engines. There is a need to reduce the viscosity before using them as engine fuel. Preheating and pre-treating of vegetable oils using waste heat of exhaust gases is one of the techniques, which reduces the viscosity and makes it possible to use as alternate fuel for some niche applications, without major modifications in the engine hardware. There are several applications in developing countries such as decentralised power generation, agricultural engines, and water pumping engines, where vegetable oils can play a significant role as an alternate fuel. In present investigations, performance, combustion, emission characteristics of an engine using preheated Jatropha oil (J100) and 20% blend of Jatropha oil with mineral diesel (J20) have been evaluated at a constant speed (1500 rpm) in a single cylinder four stroke direct injection diesel engine.
2015-04-14
Technical Paper
2015-01-1670
Can Tao, Hengjia Zhu, Peijun Xu, Yunqing Zhang
Hydraulic Engine Mount (HEM) is widely used in vehicle Powertrain Mounting System (PMS) for vibration isolation. The dynamic performances of an HEM are strongly frequency dependent. A Five-Parameters Fractional Derivative model is used to describe the dynamic properties of a HEM. A 1/4 and 1/2 car model are applied to evaluate the effect of frequency-dependent dynamic stiffness which using measured data of a typical hydraulic engine mount. The excitations from engine and road are considered in the simulation. The generalized- method is presented to solve the vehicle model with Five-Parameters Fractional Derivative model.
2015-04-14
Journal Article
2015-01-0660
Kosuke Sakamoto, Toshio Inoue
When a vehicle is in motion, noise is generated in the cabin that is composed of multiple narrow-frequency bands from input from the road surface. This type of noise is termed low-frequency-band road noise, and its reduction is sought to increase occupant comfort. The research discussed in this paper used feedback control technology for the development of an active noise control technology able to simultaneously reduce noise in multiple narrow-frequency bands. We investigated methods of connecting multiple single-frequency adaptive notch filters, a type of adaptive filter. We tested a method of connecting multiple filters that mitigates mutual interference caused by different controller transmission characteristics. This method made it possible to implement controllers with amplitude and phase characteristics in multiple narrow-frequency bands corresponding to design values, and to achieve the target noise-reduction.
2015-04-14
Technical Paper
2015-01-0672
Douglas Marriott, Takeshi Ohtomo, Tohru Wako
Predicting sloshing noise as early as possible during the design process has become an increasingly desired simulation for fuel tank suppliers. It enables suppliers to build products directly to customer specifications, at the minimum cost, in a shorter timeframe. Ideally, it needs to be run during the quote stage to avoid hidden obstacles later. The procedure to accurately and efficiently analyze sloshing noise has to date not been fully established and instead relies mostly on indirect acceleration readings to deduce the noise levels. In this paper, we introduce a new technique to analyze the sloshing noise generated in the fuel tank of an automobile to take advantage of the acoustic analysis software using infinite element and finite element methods. This technique is performed by chaining the different software for the analysis of the sloshing behavior and acoustic response together for a multi-discipline simulation result.
2015-04-14
Journal Article
2015-01-0796
Stephen Busch, Kan Zha, Paul C. Miles, Alok Warey, Francesco Pesce, Richard Peterson, Alberto Vassallo
Various pilot-main injection strategies are investigated for a part-load operating point in a single cylinder optical Diesel engine. With a pilot injection energizing signal that is advanced from the main injection by 300 µs or more, a 9 dB reduction in combustion noise is achieved. It is observed that as the energizing dwell between a single pilot and the main injection is decreased below 200 µs, combustion noise passes through a minimum and a further reduction of 3 dB is possible. This additional decrease in combustion noise is not associated with increases in smoke or NOx emissions. The injection schedules employed in the engine are analyzed with a hydraulic injection analyzer to provide rate shapes for each of the dwells tested. Two distinct injection events are observed even at the shortest dwell tested, and various rate shaping effects are observed with the main injection event as the dwell is adjusted.
2015-04-14
Journal Article
2015-01-0226
Mahdi N. Ali
Bluetooth communication systems are constrained to use a low cost filtering technology, which requires designers to implement inexpensive noise reduction techniques. Improving Bluetooth sound and audio quality has been a topic of research over the years. Sound and audio quality in vehicles are areas that still require improvements in order to achieve better customer experience when using Bluetooth communication systems. This paper proposes a low cost, simple, and effective method to reduce noise in Bluetooth systems using Kalman Filtering. Our novel method is proposed to be used in vehicular Bluetooth applications. We have created a MATLAB/SIMULINK model to validate the proposed method. Results have demonstrated significant noise reduction and improvement to the processed speech signals.
2015-04-14
Journal Article
2015-01-1657
Ahsanul Karim, Meisam Mehravaran, Brian Lizotte, Keith Miazgowicz, Yi Zhang
A computational aero-acoustics simulation on the aerodynamic noise generation of an automotive radiator fan assembly is carried out. Three-dimensional Computational Fluid Dynamics (CFD) simulation of the unsteady flow field was performed including the entire impeller and shroud to obtain the source of an audible broad-band flow noise between 2 to 4 kHz. Static pressure probes placed around the outer-periphery and at the center of the impeller inlet side and, at the shroud cavities to capture the noise sources. The static pressure at all probe locations were FFT (Fast Fourier Transform) processed and sound pressure level (SPL) was calculated. The sound pressure levels from the fan outer-periphery probes show the dominant source of blade passing frequency (BPF) and the broad-band noise. The BPF level is the strongest in fan outer-peripheral region because of large pressure fluctuations as a result of blade-passing.
2015-04-14
Journal Article
2015-01-1669
Alexei P. Popov, George Nerubenko
Increasing challenges on reducing fuel consumption has opened the new directions in Automobile Powertrain technologies. The example of such technology implemented in geared transmission is the usage of novel type of gears with 3D point system of mesh engaging invented, patented and developed by Alexei P. Popov. The paper identifies the milestones of R&D that were undertaken to create the new type of geared transmission which could be used in vehicles. Using the Winkler hypothesis Alexei P. Popov had developed and designed new type of point contact which made possible to lower a contact stresses significantly in comparison to the values of a contact stresses for teeth having linear contacting interaction. The new profile and shape of tooth was invented and the methodological tools were developed for engineers providing the formulas for design and forming geometry of tooth with high stress capacity.
2015-04-14
Journal Article
2015-01-1667
Yasunori Kanda, Tsunehiro Mori
It has been required recently that diesel engines for passenger cars meet various requirements, such as low noise, low fuel consumption, high power and strict emission limits. The key to decrease the noise is to reduce a combustion noise known as “Diesel knock”. Conventional approaches to reduce the diesel knock are decreasing combustion excitation force due to pilot/pre fuel injection, adding ribs to engine blocks or improving noise transfer characteristics by using insulation covers. However, these approaches have negative effects, such as deterioration in fuel economy and increase in cost/weight. Therefore, modification of engine structures is required to reduce it. We analyzed noise transfer paths from a piston, a con rod, a crank shaft to an engine block and vibration behavior during engine operation experimentally, and identified that piston resonance was a noise source.
2015-04-14
Journal Article
2015-01-1672
Clemens Biet, Roland Baar
Acoustic measurements, especially interesting for new bearing concepts such as ball bearings, are an important part of the evaluation of turbochargers. Typically, acoustic benchmarking is done at standard conditions, neglecting possible negative effects of very low temperatures, as they might be encountered in real-world applications. For realistic turbocharger measurements at cold environment conditions down to -10°C, special adjustments to the turbocharger test bench have been made. This article introduces a soundproofed climate chamber built in the turbocharger test bench which is able to achieve low component and oil supply temperatures while still providing adequate conditions for acoustic measurements. In addition to that, with the shown concept all of the regular turbocharger test bench measurement points stay untouched as well.
2015-04-14
Journal Article
2015-01-0856
Martin Wissink, Rolf D. Reitz
Control of the timing and magnitude of heat release is one of the biggest challenges for premixed compression ignition, especially when attempting to operate at high load. Single-fuel strategies such as partially premixed combustion (PPC) use direct injection of gasoline to stratify equivalence ratio and retard heat release, thereby reducing pressure rise rate and enabling high load operation. However, retarding the heat release also reduces the maximum work extraction, effectively creating a tradeoff between efficiency and noise. Dual-fuel strategies such as reactivity controlled compression ignition (RCCI) use premixed gasoline and direct injection of diesel to stratify both equivalence ratio and fuel reactivity, which allows for greater control over the timing and duration of heat release. This enables combustion phasing closer to top dead center (TDC), which is thermodynamically favorable.
2015-04-14
Journal Article
2015-01-0662
Weiguo Zhang, Mac Lynch, Robert Reynolds
A turbocharger is currently widely used to boost performance of an internal combustion engine. Generally, a turbocharger consists of a compressor which normally is driven by an exhaust turbine. Both the compressor and the turbine will have an influence on how the low frequency engine pulsation propagates in the intake and exhaust system. In addition, the turbocharger will produce high frequency flow induced sound. The high frequency sound generation is associated with rotating blade pressures, supersonic tip speeds or rotating shock waves. This paper focuses on the application of computational fluid dynamics (CFD) to the prediction of this high frequency flow induced sound. A turbocharger compressor is generally a centrifugal compressor consisting of wheel, diffuser and housing. As the compressor wheel rotates, ambient air is drawn in axially through an air induction system, accelerated to high speed and then expelled in a radial direction to the outlet.
2015-04-14
Journal Article
2015-01-0664
Hiroko Tada
We optimized the soundproof packages. This optimization study should be done in the early stage of vehicle development. The process for improving automotive interior quietness includes setting the marketability targets, the vehicle body acoustical performances, and the parts specifications. The acoustical system performance in this process is accomplished by evaluating the acoustical energy level of each system with the unit power of the exterior speaker excitation. The system was defined as the partial surface of the interior cavity, and one interior cavity surface was divided into a number of systems. Each system includes panel, damping material and exterior and interior soundproof packages. This system performance is named as the Energy Transmission Loss (ETL). The applicability of the method with ETL was verified by evaluating the results against the predicted values using the new method with the vehicle operation on a chasse-dynamometer.
2015-04-14
Journal Article
2015-01-0665
Yongchang Du, Yujian Wang, Pu Gao, Yingping Lv
Modelling of disc in brake squeal analysis is complicated because of the rotation of disc and the sliding contact between disc and pads. Many analytical or analytical numerical combined modeling methods have been developed considering the disc brake vibration and squeal as a moving load problem. Yet in the most common used complex eigenvalue analysis method, the moving load nature normally has been ignored. In this paper, a new modelling method for rotating disc from the point of view of modal is presented. First finite element model of stationary disc is built and modal parameters are calculated. Then the dynamic response of rotating disc which is excited and observed at spatial fixed positions is studied. The frequency response function is derived through space and time transformation. The equivalent modal parameter is extracted and expressed as the function of rotation speed and original stationary status modal parameters.
2015-04-14
Journal Article
2015-01-0668
Yongchang Du, Pu Gao, Yujian Wang, Yingping Lv
The study and prevention of unstable vibration is a challenging task for vehicle industry. Improving predicting accuracy of braking squeal modal is of great concern. Closed-loop coupling disc brake model is widely used in complex eigenvalue analysis and further analysis. The coupling stiffness of disc rotor and pads is one of the most important parameters in the model. But in most studies the stiffness is calculated by simple static force-deformation simulation. In this paper, a closed-loop coupling disc brake model is built. Initial values of coupling stiffness are estimated from static calculation. Experiment modal analysis of stationary disc brake system with brake line pressure and brake torques applied is conducted. Then an optimization process is initiated to minimize the differences between modal frequencies predicted by the stationary model and those from test. Thus model parameters more close to reality are found.
2015-04-14
Journal Article
2015-01-0667
Kei Ichikawa
The importance of reducing road noise is increasing . Methods that enhance acoustic sensitivity and reduce the force transferred from the suspension to the body are used to reduce road noise. Reduction of body suspension mounting point compliance has been used as a method of reducing acoustic sensitivity. There were cases where this method reduced acoustic sensitivity, the road noise pressure was not reduced; this study focused on the suspension transfer force and analyzed its mechanism of change using the Transfer Function Synthesis Method. The results showed that the balance between the body suspension mounting point, suspension bush and suspension arm tip compliance is an important factor influencing the change in suspension transfer force.
2015-04-14
Journal Article
2015-01-1309
Hyunggyung Kim
This paper describes about the development of new concept’s rear wheel guards for the reduction of Road Noise in the passenger vehicle using test. The new wheel guards are proposed by various frequency chamber concept and different textile layers concept. Two wheel guards were verified by small cabin resonance test and vehicle test. Through new developing process without vehicle test, Result of road noise will be expected when new concepts and materials of wheel guard is applied into automotive vehicle. As this concept consider tire radiation noise frequency and multilayers sound control multilayers, 2 concepts reduced road noise from 0.5 to 1.0 dB The suggested Estimation method of part reverberant absorption method is similar to result of vehicle tests by part absorption index. Furthermore, optimization of frequency band to wheel guards will reduce more 0.5 dB noises in vehicle.
2015-04-14
Journal Article
2015-01-1329
Katsutomo Kanai, Hideki Katsuyama
We developed a method of predictive simulation of flow-induced noise using computational fluid dynamics. Because the goal was to employ the method in the automotive development process, development sought to balance practical predictive accuracy and computation time. In order to simulate flow-induced noise, detailed eddy flows and changes in the density of the air must be computed. In the development discussed in this paper, we conducted unsteady-state compressible computations using large eddy simulation, a type of turbulence modeling, to predict whether flow-induced noise would occur. The target flow-induced noise was narrow-band noise, also known as whistling noise, a type of noise that increases in a specific frequency range. The target area of generation of flow-induced noise was set as the exhaust pipe, which incorporates the complex shape of the muffler.
2015-04-14
Journal Article
2015-01-1523
Takahiro Uesaka, Tatsuya Suma
Simulating road noise while a vehicle is operating shortens the development period and reduces the number of prototypes, which lowers development costs. Realizing road noise simulation identifies the force transmitted to the suspension through the tires and wheels from vibration between the road surface and the tires. There are significant variations between static state characteristics and vibration characteristics of tires in motion, which are challenging to measure. The effects of reduction of the elastic modulus of the rubber in the tires due to repeated loads accompanying contact with the ground, and of Coriolis and centrifugal forces resulting from the rolling motion are known. Detailed analysis of the eigenvalue fluctuations produced by Coriolis force based on measurements taken using sensors installed inside the tires has recently been reported. Knowledge is still lacking in areas such as the specifics of how the input from the tires changes due to these fluctuations.
Viewing 1 to 30 of 7358

Filter