Display:

Results

2015-04-14
Journal Article
2015-01-1206
Manabu Yazaki
Abstract A new motor has been developed that combines the goals of greater compactness, increased power and a quiet drive. This motor is an interior permanent magnet synchronous motor (IPM motor) that combines an interior permanent magnet rotor and a stator with concentrated windings. In addition, development of the motor focused on the slot combination, the shape of the magnetic circuits and the control method all designed to reduce motor noise and vibration. An 8-pole rotor, 12-slot stator combination was employed, and a gradually enlarged air gap configuration was used in the magnetic circuits. The gradually enlarged air gap brings the centers of the rotor and the stator out of alignment, changing the curvature, and continually changing the amount of air gap as the rotor rotates. The use of the gradually enlarged air gap brings torque degradation to a minimum, and significantly reduces torque fluctuation and iron loss of rotor and stator.
2015-04-14
Technical Paper
2015-01-1555
Charalampos Kounenis, David Sims-Williams, Robert Dominy, Arganthaël Berson, Nicholas Oettle, Claire Freeman
Abstract A vehicle driving on the road experiences unsteady flow conditions which are not generally reproduced in the development environment. This paper investigates the potential importance of this difference to aeroacoustics and hence to occupant perception and proposes a methodology to enable better ranking of designs by taking account of wind noise modulation. Two approaches of reproducing the effects of unsteady wind on aeroacoustics were investigated: an active wind tunnel Turbulence Generation System (TGS) and a quasi-steady approach based on measurements at a series of fixed yaw angles. A number of tools were used to investigate the onset flow and its impacts, including roof-mounted probe, acoustic heads and surface microphones. External noise measurements help to reveal the response of separate exterior noise sources to yaw.
2015-04-14
Technical Paper
2015-01-1558
Amir Kharazi, Edward Duell, Austin Kimbrell, Ann Boh
Abstract Unsteady flow over automotive side-view mirrors may cause flow-induced vibrations of the mirror assembly which can result in blurred rear-view images, adversely affecting marketability through customer comfort and quality perception. Prior research has identified two mechanisms by which aerodynamically induced vibrations are introduced in the mirror. The first mechanism is unsteady pressure loading on the mirror face due to the unsteady wake, causing direct vibration of the mirror glass. The second mechanism, and the focus of this study, is a fluctuating loading on the mirror housing caused by an unsteady separation zone on the outer portion of the housing. A time-dependent Computational Fluid Dynamics (CFD) methodology was developed to correctly model mirror wake behavior, and thereby predict flow-induced mirror vibration to improve performance estimations.
2015-04-14
Journal Article
2015-01-0610
Guangqiang Wu, Wenbo Luan
Abstract During the launch of a car, severe torsional vibration sometimes may occur in its driveline due to somewhat the slipping of the clutch, its intuitive sense for an occupant is the longitudinal vibration of the vehicle, referred to as the launch shudder whose characteristic frequency is from 5 to 25 Hz generally. As the main vibration sources of the driveline and its crucial nonlinear components, the variable stiffness and backlash of the gear meshing are considered, their impacts on the launch shudder are analyzed in this paper. Conformal mapping, finite element method and regression method etc. are the main approaches to calculate the variable meshing stiffness of a gear pair. If this stiffness is get, it can usually be substituted for its approximate analytical expression, just with finite harmonic terms, in Fourier Series form into Ordinary Differential Equations(ODEs) to calculate the vehicle responses with its nonlinearity considered.
2015-04-14
Journal Article
2015-01-0612
Weiguo Zhang, Zeyu Ma, Ankang Jin, James Yang, Yunqing Zhang
Abstract Nowadays, studying the human body response in a seated position has attracted a lot of attention as environmental vibrations are transferred to the human body through floor and seat. This research has constructed a multi-body biodynamic human model with 17 degrees of freedom (DOF), including the backrest support and the interaction between feet and ground. Three types of human biodynamic models are taken into consideration: the first model doesn't include the interaction between the feet and floor, the second considers the feet and floor interaction by using a high stiffness spring, the third one includes the interaction by using a soft spring. Based on the whole vehicle model, the excitation to human body through feet and back can be obtained by ride simulation. The simulation results indicate that the interaction between feet and ground exerts non-negligible effect upon the performance of the whole body vibration by comparing the three cases.
2015-04-14
Journal Article
2015-01-1579
Jun Nakahara, Koji Yamazaki, Yusuke Otaki
Abstract In many cars, ride is less comfortable on smooth roads. This is because when the hysteresis in the suspension components rises steeply, the increase of the equivalent spring constant at small amplitude deteriorates the vibration isolation of the suspension. Therefore suspension components should be designed to prevent a steep rises in hysteresis. Investigating the influence of hysteresis, component models, which can reproduce such hysteresis characteristics, should be installed with model parameters in the vehicle model. Using conventional methods, these parameters can be accurately identified if measurement data is provided; however, it is difficult at the earlier phase of vehicle development. Then, if conflicting performances, such as ride and handling, are to be improved, both should be considered concurrently as early in a phase of vehicle development as possible and the design specifications for suspension components should be determined to satisfy both performances.
2015-04-14
Journal Article
2015-01-1597
Kazuto Yokoyama, Masahiro Iezawa, Hideyuki Tanaka, Keiichi Enoki
Abstract Mitsubishi Electric has developed a concept car “EMIRAI 2 xEV” that features an electric vehicle (EV) powertrain for safe, comfortable, eco-friendly driving experiences in the future. The vehicle was exhibited during the 2013 Tokyo Motor Show and the 2014 Automotive Engineering Exposition. The xEV is a four-wheel-drive EV with three motors: a water-cooled front motor and two air-cooled rear motors with integrated inverters. The 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 a built-in step down DC/DC converter, an EV control unit, a battery management unit, and electric power steering. All of the instruments are developed by Mitsubishi Electric. Motion control systems for the xEV have been developed based on our proprietary motor control technology.
2015-04-14
Journal Article
2015-01-0796
Stephen Busch, Kan Zha, Paul C. Miles, Alok Warey, Francesco Pesce, Richard Peterson, Alberto Vassallo
Abstract A pilot-main injection strategy is investigated for a part-load operating point in a single cylinder optical Diesel engine. As the energizing dwell between the pilot and main injections decreases below 200 μs, combustion noise reaches a minimum and a reduction of 3 dB is possible. This decrease in combustion noise is achieved without increased pollutant emissions. Injection schedules employed in the engine are analyzed with an injection analyzer to provide injection rates for each dwell tested. Two distinct injection events are observed even at the shortest dwell tested; rate shaping of the main injection occurs as the dwell is adjusted. High-speed elastic scattering imaging of liquid fuel is performed in the engine to examine initial liquid penetration rates.
2015-04-14
Journal Article
2015-01-0856
Martin Wissink, Rolf D. Reitz
Abstract 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
2015-01-1088
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
Journal Article
2015-01-1147
Dongxu Li
Abstract A new approach for modeling and analysis of a transmission and driveline system is proposed. By considering the stiffness, damping and inertias, model equations based on lumped parameters can be created through standard Lagrangian Mechanics techniques. A sensitivity analysis method has then been proposed on the eigenspace of the system characteristic equation to reveal the dynamic nature of a transmission and driveline system. The relative sensitivity calculated can clearly show the vibration modes of the system and the key contributing components. The usefulness of the method is demonstrated through the GM 6-speed RWD transmission by analyzing the dynamic nature of the driveline system. The results can provide a fundamental explanation of the vibration issue experienced and the solution adopted for the transmission.
2015-04-14
Journal Article
2015-01-0622
H. Metered, A. Elsawaf, T. Vampola, Z. Sika
Abstract Proportional integral derivative (PID) control technique is the most common control algorithm applied in various engineering applications. Also, particle swarm optimization (PSO) is extensively applied in various optimization problems. This paper introduces an investigation into the use of a PSO algorithm to tune the PID controller for a semi-active vehicle suspension system incorporating magnetorheological (MR) damper to improve the ride comfort and vehicle stability. The proposed suspension system consists of a system controller that determine the desired damping force using a PID controller tuned using PSO, and a continuous state damper controller that estimate the command voltage that is required to track the desired damping force. The PSO technique is applied to solve the nonlinear optimization problem to find the PID controller gains by identifying the optimal problem solution through cooperation and competition among the individuals of a swarm.
2015-04-14
Journal Article
2015-01-0664
Hiroko Tada
Abstract The process for setting the marketability targets and achievement methods for automotive interior quietness (as related to air borne noise above 400Hz, considered the high frequency range) was established. With conventional methods it is difficult to disseminate the relationship between the performance of individual parts and the overall vehicle performance. Without new methods, it is difficult to propose detailed specifications for the optimal sound proof packages. In order to make it possible to resolve the individual components performance targets, the interior cavity was divided into a number of sections and the acoustic performance of each section is evaluated separately. This is accomplished by evaluating the acoustical energy level of each separate interior panel with the unit power of the exterior speaker excitation. The applicability of the method was verified by evaluating result against predicted value, using the new method, during actual vehicle operation.
2015-04-14
Journal Article
2015-01-0662
Weiguo Zhang, Mac Lynch, Robert Reynolds
Abstract A turbocharger is currently widely used to boost performance of an internal combustion engine. Generally, a turbocharger consists of a compressor which typically is driven by an exhaust turbine. The compressor will influence how the low frequency engine pulsation propagates in the intake system. The compressor will also produce broad-band flow induced sound due to the turbulence flow and high frequency narrowband tonal sound which is associated with rotating blade pressures. In this paper, a practical simulation procedure based on a computational fluid dynamics (CFD) approach is developed to predict the flow induced sound of a turbocharger compressor. In the CFD model of turbocharger compressor, the unsteady, moving wheel, detached eddy simulation (DES) approach are utilized. In this manner, both the broad-band and narrow-band flow induced sound are directly resolved in the CFD computation.
2015-04-14
Journal Article
2015-01-0667
Kei Ichikawa
Abstract Cabin quietness is one of the important factors for product marketability. In particular, the importance of reducing road noise is increasing in recent years. Methods that reduce acoustic sensitivity as well as those that reduce the force transferred from the suspension to the body (the suspension transfer force) are used as means of reducing road noise. Reduction of the compliance of the body suspension mounting points has been widely used as a method of reducing acoustic sensitivity. However, there were cases where even though this method reduced acoustic sensitivity, road noise did not decrease. This mechanism remained unclear. This study focused on the suspension transfer force and analyzed this mechanism of change using the transfer function synthesis method. The results showed that the balance between the body's suspension mounting points, suspension bush, and suspension arm-tip compliance is an important factor influencing the change in suspension transfer force.
2015-04-14
Journal Article
2015-01-0665
Yongchang Du, Yujian Wang, Pu Gao, Yingping Lv
Abstract 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 transformations. 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
2015-01-0660
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
Journal Article
2015-01-0668
Yongchang Du, Pu Gao, Yujian Wang, Yingping Lv
Abstract The study and prevention of unstable vibration is a challenging task for vehicle industry. Improving predicting accuracy of braking squeal model 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
2015-01-1309
Hyunggyung Kim
Abstract This Study describes about the development of new concept' rear wheel guards for the reduction of Road Noise in the passenger vehicles. 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 and vehicle tests. Through new developing process without vehicle test, Result of road noise will be expected if this concepts and materials of wheel guard are 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 1.0dB. The proposed method of part reverberant absorption is similar to results of vehicle tests by part absorption index. Furthermore, optimization of frequency band in wheel guards will reduce more 0.5 dB noises.
2015-04-14
Journal Article
2015-01-1329
Katsutomo Kanai, Hideki Katsuyama
Abstract A method of predictive simulation of flow-induced noise using computational fluid dynamics has been developed. The goal for the developed method was application in the vehicle development process, and the target of the research was therefore set as balancing the realization of a practical level of predictive accuracy and a practical computation time. In order to simulate flow-induced noise, it is necessary to compute detailed eddy flows and changes in the density of the air. In the research discussed in this paper, the occurrence or non-occurrence of flow-induced noise was predicted by conducting unsteady compressible flow calculation using large eddy simulation, a type of turbulence model. The target flow-induced noise for prediction was narrow-band noise, a type of noise in which sound increases in specific frequency ranges.
2015-04-14
Journal Article
2015-01-1506
Bastian Scheurich, Tilo Koch, Michael Frey, Frank Gauterin
Abstract 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 vibrational energy. Different damper characteristics are achieved by different induced precession. From almost zero torque output to high torque output, this damper has a huge spread. Next to the basic principal, in this paper an integration in the chassis, including a constructive proposal is shown. A conflict with high torque and high angular velocity leads to a special design. Moreover concepts to deal with all vehicle situations like yawing, rolling and pitching are shown.
2015-04-14
Journal Article
2015-01-1523
Takahiro Uesaka, Tatsuya Suma
Abstract Development of simulation technology for road noise while a vehicle is in operation has become an important issue. Because a fixed technological architecture has been established for simulation of the body and the suspension, the issue in realizing road noise simulation is how to accurately identify the force transmitted to the suspension through the tires and wheels by vibration input due to contact between the road surface and the tires. The issue here is that there are significant variations between static state characteristics, which are easy to measure, and vibration characteristics of tires in motion, which are challenging to measure. A variety of expertise regarding the sources of this discrepancy has been published. Among these, the effects of Coriolis and centrifugal forces resulting from the rolling motion are known.
2015-04-14
Journal Article
2015-01-1531
Hangsheng Hou
Abstract Wind noise, an aeroacoustic phenomenon, is an important attribute that influences customer sensation of interior quietness in a moving vehicle. As a vehicle travels faster, occupants' sensation of wind noise becomes increasingly objectionable. The purpose of this work is to investigate the increase of wind noise level perceived by a driver in response to an increase in wind speed. Specifically, it explores how much the level of wind noise at the DOE (driver outboard ear) would vary in response to a change in wind speed based on the test data obtained in a wind tunnel from ten vehicles that belong to several different passenger vehicle segments. The first part of this work studies the change of the SPL (sound pressure level) in response to a change in wind speed U. It shows that the SPL(dBA) approximately scales to U5.7 at the DOE and to U6.3 in the far-field, which could be interpreted as the dominance of dipoles.
2015-04-14
Journal Article
2015-01-1532
Nicholas Oettle, Mohammed Meskine, Sivapalan Senthooran, Andrew Bissell, Gana Balasubramanian, Robert Powell
Abstract 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 (also known as boom) targets and broadband noise targets for the fully open sunroof with deflector and for the sunroof in vent position. 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
2015-01-1583
Timothy Drotar, Jacopo Palandri, Friedrich Wolf-Monheim, Paul Zandbergen, Bjoern Reff
Abstract One of the key challenges in developing a vehicle for excellent vehicle dynamics is being able to achieve a high level of driving comfort without degrading the steering and handling performance. The part of driving comfort discussed in this paper are tactile vibrations up to f = 100 Hz. This paper describes how Multi-Body Dynamics (MBD) Computer Aided Engineering (CAE) tools are applied to optimize such vibrations in the early phase of the development process. The approach hereby presented combines system level testing with MBD for the study of ride comfort, similar to the way that system level kinematics and compliance testing is combined with MBD to support steering and handling investigations. Laboratory investigations have been executed to fully characterize a reference suspension with respect to frequency and amplitude behavior. The respective MBD models have been subsequently refined and validated versus physical laboratory measurements.
2015-04-14
Technical Paper
2015-01-0831
Wonah Park, Youngchul Ra, Eric Kurtz, Werner Willems, Rolf D. Reitz
Abstract 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, 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 distribution can be used as a control factor for emissions and noise.
2015-04-14
Technical Paper
2015-01-1122
Kengo Yabe, Toru Inagaki, Takashi Kondo
Abstract Seat vibration when a vehicle is idling or in motion is an issue in automobile development. In order to reduce this vibration, dynamic damper or inertia mass is widely used. These countermeasures increases vehicle's weight and causes bad fuel-efficiency. Some new ways to reduce the vibration without weight increase are needed. One of that is the floating seat. Seat vibration has been reduced by controlling seat resonance frequencies. In order to control resonance frequency, the structures of the seat-mounting unit are replaced with floating structures using rubber bushings. It was demonstrated that partially replacing the mounting unit with floating structures makes it possible to control the resonance frequencies of the entire seat. The issue of balancing vibration reduction with strength and durability and crash safety performance caused by the fitting of rubber bushings to the seat-mounting unit was addressed using stopper structures optimized for each type of input.
2015-04-14
Journal Article
2015-01-1657
Ahsanul Karim, Meisam Mehravaran, Brian Lizotte, Keith Miazgowicz, Yi Zhang
Flow bench and engine testing can be used to detect flow induced noise, but understanding the fundamental mechanisms of such noise generation is necessary for developing an effective design. This paper describes Computational Aero-Acoustic (CAA) analyses performed to obtain the broad-band and BPF noise sources 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.
2015-04-14
Journal Article
2015-01-1667
Yasunori Kanda, Tsunehiro Mori
Abstract It has been required recently that diesel engines for passenger cars meet various requirements, such as low noise, low fuel consumption, low emissions and high power. The key to improve the noise is to reduce a combustion noise known as “Diesel knock noise”. 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 connecting 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
2015-01-1674
Takashi Hoshi
Abstract A clutch FEM model was created to quantitatively understand the operation and dynamic friction characteristics of the facing materials. And a simulation model for dynamic behavior analysis of the torque transmission characteristics from a transmission that incorporates drivetrain damping characteristics to the vehicle body was constructed. The data of the actual vehicle was also measured when vibration occurs and loss torque is generated by friction in the drivetrain, and damping characteristics were determined from the measurement values. In order to confirm the usefulness of this method, the construction of a clutch that suppresses self-excited vibration was examined by simulation and the reduction of vibration in an actual vehicle was confirmed.

Filter

Subtopics