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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
Technical Paper
2015-01-0617
Jie Zhang, Xiao Chen, Bangji Zhang, Lifu Wang, Shengzhao Chen, Nong Zhang
Well-deigned suspension system plays an important role in improving ride comfort. Underground mining vehicles which work in harsh conditions commonly employ leaf spring suspension to provide large stiffness and damping while be compact in size. Another characteristic of the mining vehicle is that its sprung mass varies significantly when loaded/unloaded. The leaf spring suspension has to be designed very stiff to meet the full-loaded requirement, therefore when the vehicle is unloaded, the stiff leaf spring damage the ride quality and expose the passengers to noise, vibration and harshness. Since the hydraulic suspension systems can provide better ride comfort, the paper proposes a design of adding an interconnected hydraulic system to resist bounce motions to share the vertical load with the leaf spring, which therefore can be designed softer. Furthermore, The hydraulic system also increases the suspension stiffness in the pitch mode to prevent vehicle from large pitch motions.
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
2015-01-1523
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.
2015-04-14
Journal Article
2015-01-1531
Hangsheng Hou
Wind noise, an aeroacoustic phenomenon, is an important attribute that impacts the customer sensation of interior quietness in a moving vehicle. Aeroacoustic noise sources include monopole, dipole and quadrupole types, with the intensity of these sources scaling with wind speed in terms of different exponents U4, U6, U8 respectively. The first part of this work studies the wind noise data obtained in the wind tunnel based on several vehicles. The results show that, for adequately designed vehicles, the sound pressure level at driver’s outboard ear location scales approximately with logU6, which corresponds to a U6 dependence for the sound intensity. This demonstrates that the dipole source generated by the aerodynamic flow plays a major role in the process of wind noise generation. The second part of this work looks into the loudness information expressed in Zwicker Sones, which represents the human hearing organ sensation of the wind noise loudness.
2015-04-14
Journal Article
2015-01-1532
Nicholas Oettle, Mohammed Meskine, Sivapalan Senthooran, Andrew Bissell, Gana Balasubramanian, Robert Powell
Car manufacturers put large efforts into reducing wind noise to improve the comfort level of their cars. Each component of the vehicle is designed to meet its individual noise target to ensure the wind noise passenger comfort level inside the vehicle is met. Sunroof designs are tested to meet low-frequency buffeting targets as well as broadband noise targets for the sunroof in vent position and any noise generated by deflectors. Experimentally testing designs and making changes to meet these design targets typically involves high cost prototypes, expensive wind tunnel sessions, and potentially late design changes. To reduce the associated costs as well as development times, there is strong motivation for the use of a reliable numerical prediction capability early in the vehicle design process.
2015-04-14
Journal Article
2015-01-1579
Jun Nakahara, Koji Yamazaki, Yusuke Otaki
There exist some cars which ride performance become less comfortable on smooth road. If vibration transmissibility of suspension system on such a vehicle is evaluated by means of equivalent dynamic stiffness, it is found that the increase of storage stiffness deteriorates the vibration transmissibility of suspension due to the steep rising of hysteresis on wheel-stroke to wheel-load curve when excitation amplitude become small. To improve the ride-comfort performance on smooth road, therefore, the rising shape of wheel stroke curve due to hysteresis components, such as shock-absorber, ball-joints and rubber bushes, should be adjusted to prevent the increase of storage stiffness at small amplitude of suspension stroke. For investigating the hysteresis characteristics of these components, appropriate simulation models, which can reproduce their characteristics accurately, must be installed in the vehicle model and their parameters have to be determined with sufficient accuracy.
2015-04-14
Journal Article
2015-01-1583
Timothy Drotar, Jacopo Palandri, Friedrich Wolf-Monheim, Paul Zandbergen, Bjoern Reff
This paper describes how chassis system rig tests and Multi-Body Dynamics (MBD) Computer Aided Engineering (CAE) tools are applied to optimize the transfer functions across chassis-to-body attachments associated with driving comfort in the early phases of the development process. Several examples are given. A first example demonstrates the effect of subframe isolation to ride comfort via analyses of the forces transmitted to the vehicle body. A second example demonstrates the sensitivity of bushing stiffness to impact harshness using a full vehicle model. A final example demonstrates how impact harshness can be optimized using different levels of compliance split between the subframe and sus-pension bushings.
2015-04-14
Journal Article
2015-01-1597
Kazuto Yokoyama, Masahiro Iezawa, Hideyuki Tanaka, Keiichi Enoki
Mitsubishi Electric has developed a concept car “EMIRAI 2 xEV” that features an electric vehicle (EV) powertrain for safe, comfortable, and eco-friendly driving experiences in the future. The body of vehicle was exhibited during Tokyo Motor Show 2013 for the first time. xEV is a four-wheel-drive EV that has three motors: a water-cooled front motor and two air-cooled rear motors with integrated inverters. Rear wheels can be driven independently. The degrees of freedom of the actuation can realize improved maneuverability and safety. The vehicle is also equipped with an onboard charger with built-in step down DC/DC converter, an EV control unit, a battery management unit, and an electric power steering. All of the instruments are developed in Mitsubishi Electric Corporation. Motion control systems for xEV have been developed on the basis of our proprietary original motor control technology.
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
2015-01-0665
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
2015-01-0664
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
2015-01-0668
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
2015-01-1506
Bastian Scheurich, Tilo Koch, Michael Frey, Frank Gauterin
Today, body vibration energy of passenger cars gets dissipated by linear working shock absorbers. A new approach substitutes the damper of a passenger car by a cardanic gimbaled flywheel mass. The constructive design leads to a rotary damper in which the vertical movement of the wheel carrier leads to revolution of the rotational axis of the flywheel. In this arrangement, the occurring precession moments are used to control damping moments and to store vibration energy. A gyroscope is set to high speed revolutions by an electric motor and a gimbal is used for bearing. The gimbal consists of an outer ring which is connected to the vertical movement of the wheel carrier. Right-angled to the outer ring, there is an inner ring pivoting the gyroscope right-angled. In order to avoid undesirable body movements, the directional vector of the angular velocity of the gyroscope is parallel to the car’s yaw axis.
2015-04-14
Journal Article
2015-01-1088
Tomohiko Usui, Tomoya Okaji, Tatsuya Muramatsu, Yoshiyuki Yamashita
Abstract By optimizing parameters related to damping performance and adopting a layout that incorporates the turbine into the damper components, a “Turbine Twin-Damper” lock-up damper was developed that achieves both damping performance and compactness. To reduce losses in the fluid flow channel, a smaller torus was developed that reduce the width of the torus by about 30%.Through the combination of this Turbine Twin-Damper and smaller torus, attenuation of the torque fluctuation transmitted to the transmission to 1/2 or less compared to a conventional product was achieved without increasing the overall width of the torque converter. As a result, the engine speed at cruise fell by 400rpm, and fuel economy improved.
2015-04-14
Technical Paper
2015-01-0625
Manfred Baecker, Axel Gallrein, Michael Roller
Abstract The tire plays a fundamental role in the generation of acoustically perceptible driving noise and vibrations inside the vehicle. An essential part of these vibrations is induced by the road excitation and transferred via the tire into the vehicle. There are two basic ways to study NVH behavior: Simulations in time and frequency domains. The system can be simulated using a transient simulation method with the disadvantage of high simulation and process turnaround times. Alternatively, a linearization around a stationary state is performed and solved in frequency domain with fast numerical schemes. Modelling the tire transfer behavior in frequency domain requires special attention to the rotation of the tire. This paper shows the approach taken by the authors to include the transfer behavior in the frequency range up to 250 Hz from geometric road excitations to resulting spindle forces in frequency domain. Special care has been used in the modelling of local road excitations.
2015-04-14
Technical Paper
2015-01-0615
Li Jie, Wang Wenzhu, Gao Xiong
Abstract In order to study the influence of body flexibility on the truck ride comfort, a 4 DOF half vibration model of truck based on the motion synthesis between rigid body and body flexibility is established using elastic beam theory of equal section with both free ends. At the same time, a corresponding 2 DOF rigid vibration model is also built. The frequency response functions of system and response variables of two models are derived based on front wheel. The power spectral densities and the root mean square values of body acceleration, dynamic deflections and relative dynamic loads are obtained. By comparing the simulation results of rigid-elastic model and rigid model, it shows that body flexibility has a great impact on truck ride comfort and it cannot be ignored.
2015-04-14
Journal Article
2015-01-0660
Kosuke Sakamoto, Toshio Inoue
Abstract When a vehicle is in motion, noise is generated in the cabin that is composed of noise in multiple narrow-frequency bands and caused by input from the road surface. This type of noise is termed low-frequency-band road noise, and its reduction is sought in order to increase occupant comfort. The research discussed in this paper used feedback control technology as the basis for the development of an active noise control technology able to simultaneously reduce noise in multiple narrow-frequency bands. Methods of connecting multiple single-frequency adaptive notch filters, a type of adaptive filter, were investigated. Based on the results, a method of connecting multiple filters that would mitigate mutual interference caused by different controller transmission characteristics was proposed.
2015-04-14
Technical Paper
2015-01-0672
Douglas Marriott, Takeshi Ohtomo, Tohru Wako
Abstract Predicting sloshing noise as early as possible during the design process has become an increasingly desired simulation for fuel tank suppliers as the demand for quieter vehicles increase. Simulating early on in the design process enables suppliers to build products directly to customer specifications, at a lower cost and shorter timeframe. The procedure to accurately and efficiently analyze complete sloshing noise behavior has to date not been fully established. Current methods rely on indirect noise deduction based on specific positions from Fluid-Structure Interaction (FSI) analyses or uncoupled fluid analysis with separate structural and acoustic analyses. In this paper, we introduce a technique to analyze the fully coupled sloshing noise generated in the fuel tank of an automobile. The technique takes advantage of combining an explicit coupled Lagrangian and Eulerian solver with an acoustics solver.
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
2015-01-1657
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
2015-01-1674
Takashi Hoshi
For multi plate wet clutches in transmission systems, an understanding of the dynamic frictional characteristics of the friction surfaces and damping characteristics of the drivetrain are essential in predicting self-excited vibration. We made a test apparatus for torque transmission characteristics and measured the dynamic frictional characteristics of the friction surfaces at a uniform contact pressure. An understanding was gained of the changes in dynamic frictional characteristics due to temperature and contact pressure relating to the sliding velocity. We also obtained the damping characteristics by measuring the torque loss due to drivetrain friction. We created a clutch FEM model to gain a quantitative understanding of how to implement the dynamic frictional characteristics. Taking the damping characteristics of the drivetrain into consideration, we also made a plant model encompassing all areas from the transmission to the vehicle body.
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
2015-01-1669
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.
2015-03-30
Technical Paper
2015-01-0106
Zhe Yu, Wenjie Qin, Qingdong Hou, Mu Tang, Yang Ran
Abstract Wiper noise generated in the wiping process is one of the main influence factors affecting the driving comfort. Since the dynamic contact pressure of the contact between a blade and a windshield glass is difficult to be measured, it is also difficult to predict the degree of the wiper noise. In this paper, in the view of the reversal noise problem of a passenger-vehicle windscreen wiper system, the system dynamic models of the both wipers on the sides of the driver and copilot were built as considering the blade deformation and the elastic contact between the blades and the windscreen glass, including the crank pivot, the four linkage mechanism, the wiper blades, the wiper arms and the windscreen glass. The motion of the wiper system and the pressure distributions between the blades and the windscreen glass were analyzed under the half-dry condition.
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