Whine Noise Research Articles

Investigation and refinement of gearbox whine noise

Structure borne noises can be transmitted to interior cabin via physical connections by gearbox as well as other active components. Experimental Transfer Path Analysis (TPA) methods are utilized to investigate main paths of vibrations which are eventually perceived as noise components inside the cabin. In this study, contribution ranking of transmission paths from active system components through the physical connections into the interior cabin are investigated by Operational Path Analysis with Exogenous Inputs (OPAX) method. In addition, the sensitivity and rigidity characterization of the body through dominant paths according to OPAX were measured to reveal the reason for the whine noise to the inner cabin because of the operational forces generated in the dominant structure-borne paths. And also, operational modal analysis was carried out to examine the modes of the dominant path components. The modifications are applied on dominant transfer paths according to dominant paths characterization by operational deflection shape analyses. Thus, the root causes are investigated on vehicle level NVH tests while observing the variations in the interior cabin noise level.

5속 수동 트랜스미션의 전달오차 예측에 관한 연구

For the manual transmission gearbox used in the automotive industry, gear meshing transmission error is the main source of noise known as gear whine, and radiated gear whine noise plays an important role in the whole gearbox. Therefore, in order to keep competitive in the automotive market, the NVH performance of transmission gearboxes is increasingly important for automotive manufacturers when a new product is developed. In this paper, in order to achieve an optimized tooth contact pattern, gear tooth modification is applied to make up for the deformation of the teeth owing to load. A five-speed MT gearbox is firstly modeled in RomaxDesign software and the prediction of transmission error under the loaded torques is studied and compared. From the simulation, the transmission error and maximum contact stress are also simulated and compared after tooth modification of the loaded torques. Finally, the simulation results are used to optimize the whole gearbox design and the final gearbox prototype is testified to obtain NVH performance in a semi-anechoic room.

Numerical estimation of dynamic transmission error of gear by using quasi-flexible-body modeling method

When the power transmission systems are designed or improved, an understanding of gear dynamics is essential and very important. Gear systems are not easy to investigate because gear noise has to be carefully controlled. As a result, when designing and developing gear transmission systems, it is very important to grasp the noise and reduce it. Also, it is necessary to make a clear distinction between rattle noises and whine noises. The rattle noise occurs by mainly hitting the tooth, and whine noise occurs by mainly rubbing the tooth in meshing. Therefore, the whine noise is relatively related to high frequency characteristics. Our aim was to find a good way to evaluate whine noise with a numerical approach. When the gear dynamics are investigated to evaluate the whine noise, the dynamic transmission error (DTE) can be utilized. But, it is very difficult to obtain the DTE results by means of not only experimental ways but also numerical calculations. Although multi-body dynamics software has not been able to calculate the DTE practically yet, there is a possibility that the software can get the DTE results. Therefore, we propose a numerical modeling method to obtain the DTE results by using multi-body dynamics software (RecurDyn). To reduce the calculation time and represent flexibility, a rotational joint and force element with the bending stiffness are applied between gear teeth and trunk. Also the numerical results have been compared with the experimental data. The results show a good agreement with the experimental results.

기어 소음 품질 안정화를 위한 전달오차 측정 시스템 개발 및 전달오차 스펙 개발에 대한 연구

In the past, transmission error(T.E.) has been identified as one of the main sources of gear whine noise, which cause serious passengers irritation at high frequency. In this study, to identify the correlation of the T.E. and gear whine noise, a T.E. measuring system was developed. By comparing the T.E. and gear whine noise level, T.E. target value which can represent the gear noise was proposed. The conclusions are followed: (I) It is possible to measure T.E. of the gear pairs (II) Similar trends are observed between T.E. and gear whine noise. (III) By observing the T.E. pattern, presence of sideband noise can be predicted. (IV) Proposed T.E. target value can be adopted to the gear manufacturing for gear noise quality management.

Dynamics of High-Speed Precision Geared Rotor Systems

Gears are one of the most widely applied precision machine elements in power transmission systems employed in automotive, aerospace, marine, rail and industrial applications because of their reliability, precision, efficiency and versatility. Fundamentally, gears provide a very practical mechanism to transmit motion and mechanical power between two rotating shafts. However, their performance and accuracy are often hampered by tooth failure, vibrations and whine noise. This is most acute in high-speed, high power density geared rotor systems, which is the primary scope of this paper. The present study focuses on the development of a gear pair mathematical model for use to analyze the dynamics of power transmission systems. The theory includes the gear mesh representation derived from results of the quasi-static tooth contact analysis. This proposed gear mesh theory comprising of transmission error, mesh point, mesh stiffness and line-of-action nonlinear, time-varying parameters can be easily incorporated into a variety of transmission system models ranging from the lumped parameter type to detailed finite element representation. The gear dynamic analysis performed led to the discovery of the out-of-phase gear pair torsion modes that are responsible for much of the mechanical problems seen in gearing applications. The paper concludes with a discussion on effectual design approaches to minimize the influence of gear dynamics and to mitigate gear failure in practical power transmission systems.

Vibroacoustic Modeling and Path Control of Air-Borne Axle Whine Noise

The axle whine noise will eventually affect the vehicle noise performance. In this study, a systematic modeling approach is developed to analyze the axle whine problem by considering the hypoid gear mesh from the tooth contact process as well as the system dynamics effect with gear design parameters and shaft-bearing-housing system taken into account. Moreover, the tuning of the dominant air-borne path is modeled analytically by using the sound transmission loss idea. First, gear tooth load distribution results are obtained in a 3-dimensional loaded tooth contact analysis program. Then mesh parameters are synthesized and applied to a linear multibody gear dynamic model to obtain dynamic mesh and bearing responses. The bearing responses are used as the excitation force to a housing finite element model. Finally, the vibroacoustic analysis of the axle is performed using the boundary element method; sound pressure responses in the axle surface are then simulated. Transmission losses of different panel partitions are included in the final stage to guide the tuning of air-borne paths to reduce the radiated axle whine noise. The proposed approach gives a more in-depth understanding of the axle whine generation and therefore can further facilitate the system design and trouble-shooting.

Design Principles of Controlling Vehicle Gear Whine Noise Based on Loudness Metric

In-vehicle noise is composed of a variety of tonal (frequency-related) components and the tonal components play an important role in the improvement of sound quality for interior vehicle noise. Among them, gear whine noise is the key contributor to total in-vehicle noise and gain a lot of researchers interest. Through their effort, thespl (dBA)is relatively low. However, customers still perceive the tonal components and complain about the vehicle quality. Therefore a better understanding of how tonal components are perceived is necessary for automotive gear transmission designers. In this study, firstly, gear dynamic behavior is briefly introduced to get the gear noise spectrum. Secondly, human hearing mechanism to different tonal components is summed. Then loudness case studies are conducted. Finally, some basic design principles of controlling gear whine noise are proposed based on the results.

A study on tooth modification and radiation noise of a manual transaxle

In recent years, there is a trend that lower gear noise levels are demanded for drivers to avoid annoyance and fatigue during operation. For the manual transaxle, meshing transmission error (T.E.) is the excitation that leads to the tonal noise known as gear whine, and radiated gear whine is also the dominant source of noise in the whole gearbox. This paper presents a method for the various interaction analysis of gear tooth profile and lead crowning modification, and the prediction of transmission error under the loaded torques for the 3rd gear pairs of two proposalsin the manual transaxle. And transmission error, root stress and contact stress are also calculated and compared before and after tooth micromodification under one torque. At last, the gear whine noise of the 3rd gear in WOT (Wide Open Throttle) and the coasting operation condition is investigated and compared between the two proposals. The simulation and test show that the transmission error and contact stress under the loaded torque can be minimized by the appropriate tooth modification. It is a good approach which the simulated result is used to improve the design in order to minimize the radiation gear whine noise.

A study on axle gear whine noise reduction with deflection test

Hypoid gears are used in rear drive and four-wheel drive (4WD) vehicle axles. For this reason, hypoid gear whine noise has long been recognized as a problem, but there have been few or no studies of problem-solving techniques or procedures. This study analysed the possible causes of hypoid gear whine noise for its reduction and investigated the data that should be considered for the optimal shape design of hypoid gears in axle-based vehicles and the procedures for using the data for optimization. For these purposes, a hot deflection test was performed, using an actual gear mounting and the temperature of a cast-aluminium axle housing, with completely processed gear. This test covered the operating range of gear loads, from ‘no load’ to ‘peak load’. Under peak load conditions, the contact pattern extended to the tooth boundaries without showing a concentration at any point on the tooth surface. The transmission error was tested on an axle assembly triaxial real car load and at the correct temperature condition of the axle housing.

Axle whine phenomenon in light trucks: a combined numerical and experimental investigation

Axle whine is a continuous, steady state tonal sound, emitted from the differential unit’s hypoid gears. It is essentially induced by torque variations. This can be as a result of resonant conditions or torque fluctuations caused by engine order vibrations, compounded by gear transmission error. The principal mechanism of gear whine noise generation is, therefore, through transmission of vibration from the gear shafts and bearings to the differential housing, which is radiated as noise. Furthermore, interactions between the differential unit, axles and driveshafts often generate excessive tonal noises, which are the result of coupled bending and torsional resonances of assembled components. These resonances induce a magnification effect upon the noise source itself through exciting the gear shafts and distorting the alignment of the gear sets. Axle whine noise has become an important noise, vibration and harshness (NVH) concern, because of the nature of the noise; further compounded by the human aural system, which is highly sensitive in tonal memory. The result is continuously increasing warranty costs or use of expensive palliatives to mitigate the phenomenon. In this paper, a combined experimental and numerical investigation of axle whine in a rear-wheel-drive light truck is presented. The aim is to reveal some root causes of the drivetrain’s NVH behaviour, which can be related to the amplification/reduction of axle whine vibration and noise. Correlation of the experimental results with the vibration modes of the drivetrain has shown that for vehicle coasting conditions a number of modes are excited, which can interact with the vibrations of the hypoid gear pair. Finally, some light is shed on the role that differential bulk oil temperature plays in the severity of the ensuing vibration.

Deflection test and transmission error measurement to identify hypoid gear whine noise

T-Hypoid gears are commonly used in rear-drive and 4WD (4 Wheel Drive) vehicle axles. Investigating their sensitivity to deflections is one of the most important aspects of their design and optimization procedures. Therefore, a deflection test was performed in this study in the actual gear mounting using completely processed gear. This test covered the full operating range of gear loads from “no load” to “peak load”. Under peak load, the contact pattern extended to the tooth boundaries without showing a concentration of the contact pattern at any point on the tooth surface. The transmission error was tested under an axle assembly triaxial-real-car-load condition.

Reduction Design of Vibration and Noise in IPMSM Type Integrated Starter and Generator for HEV

Integrated starter and generator (ISG) is working as starter after vehicle idle stopping and generator during vehicle driving. When ISG works as starter to operate engine, ISG produces maximum power at the operating speed 4000 rpm to remove vibration of initial starting of the engine. In that time ISG produces whine noise which can be detected inside a vehicle. There are two methods to reduce the vibration and noise. One is improving the stiffness of stator and the other is reduction of electromagnetic exciting force. Although improvement of stiffness using mechanical design is utilized effectively to reduce whine noise, the electromagnetic design using the reduction of exciting forces is more reasonable in the same motor size. Because ISG produces torque ripple, radial force and tangential force on operating condition, this paper deals with the reduction design of electromagnetic exciting forces which affect the noise and vibration. Two design variables are selected to optimize the rotor shape especially geometry of flux barrier, and response surface methodology (RSM) is applied as an optimization method. Finally, quantity of the vibration and noise of optimized model are compared with prototype model, and the noise measured in the vehicle engine bay was reduced from 27 dB(A) to 25 dB(A).

Effect of sliding friction on gear noise based on a refined vibro-acoustic formulation

An improved source-path-receiver model of a single mesh geared system is developed and validated to quantify the effect of sliding friction between gear teeth on the structure-borne whine noise. The source sub-system of a spur gear pair predicts interfacial bearing forces in the line-of-action and off line-of-action directions for two whine excitations (static transmission error and sliding friction). Next, a finite element model of the gearbox with embedded bearing stiffness matrices is developed to characterize the structural paths and to calculate the surface velocity distributions. Predictions are first validated by comparing with structural modal tests and transfer function measurements from gear mesh to the housing plates. Radiated noise is then estimated by using two approximate methods, namely the Rayleigh integral method and a substitute source technique. The overall vibro-acoustic model is validated by comparing radiated sound pressure calculations with measured noise data over a range of operating torques. The proposed formulation provides an efficient analytical and computational tool to quantify the relative contribution of sliding friction to the structure-borne noise, which is found to be significant when the transmission error is minimized say via tooth modifications.

Identification of the interior noise generated by sport utility vehicle axles and structural modification of the axle system for noise reduction

This paper presents experimental and analytical methods for reducing the interior noise generated by the axle system of a sport utility vehicle. The test vehicle has a whine noise problem at the passenger seats. To identify the transfer path of the interior noise caused by the axle system, a vibration path analysis, modal analysis, and operational deflection shape analysis are systematically employed. It has been found that the interior noise generated by the axle system was airborne noise. To predict and reduce the whine noise generated by the axle system, structural modifications for the axle system are performed by using the finite element method and the boundary element method techniques. Throughout this modification the whine noise was reduced by 3—4 dBA.

Identification and reduction of noise from axles in a passenger vehicle

With reduction in engine noise, the axle has become an important noise source in a sport utility vehicle (SUV). This paper presents experimental and analytic analyses for reducing the whine at passenger locations from noise generated by the axle system of a SUV. To identify the transfer path of the interior noise caused by the axle system, a vibration path analysis, modal analysis and operational deflection shape analysis are systematically employed. To reduce the whine noise generated by the axle system, structural modifications for the axle system are performed. Throughout this modification the reduction of the whine noise is estimated.

204 かみあい伝達誤差とかみあい点動剛性を考慮したギヤノイズ低減(OS06-1 歯車の振動・騒音I)

Reduction of mesh force is important to improve gear whine noise of an automotive transmission. Mesh force is defined by multiplication of transmission error and dynamic stiffness. To reduce mesh force, it is often hard to improve both of them simultaneously because they are incompatible with each other. In this study, a face width of a counter gear set in an automatic transmission is focused on as an example of incompatibility. In this case, it is possible to improve dynamic stiffness by decreasing flexural rigidity of a counter drive gear, but it leads to deterioration of transmission error. Influence of a face width upon mesh force is guessed by numerical methods considering both of them synthetically, and validity of the methods is verified through experimental analysis.

SUV용 액슬의 소음원 규명 및 소음 저감을 위한 액슬의 구조변경에 관한 연구

This paper presents experimental and analytic methods to reduce interior noise generated by car axle. The test vehicle has a whine noise problem at passenger seats. In order to identify transfer path of interior axle noise, the vibration path analysis, the modal analysis and running modal analysis are systematically employed. By using these various methods, it has been founded that the interior noise generated by car axle was air borne noise. To reduce and predict axle noise, various structural modifications are performed by using FEM and BEM techniques, respectively. Through the modification of the axle structure, the air borne noise of the axle was reduced 3<TEX>$\sim$</TEX>4 dBA level.

도로소음 저감을 위한 타이닝 간격 랜덤화에 관한 연구

When driving on uniformly tining concrete pavement road, the whine noise which has high spectrum at the specific frequency related to the uniform tining space exist. In this paper, a randomization method of tining space for concrete pavements is proposed to reduce the whine noise. The proposed method is developed based on the LCG(linear congruential generator) algorithm. The design parameters used in the method are number of different tining space, ratio of each tining space, total linings of each size. sequence of actual tining under given constant drag length and texture. Monte Carlo simulations are used to validate the proposed method.

Experimental study on active vibration control of a gearbox system

An active internal gearbox structure is developed and evaluated experimentally to suppress gear pair vibration due to transmission error excitation. The approach is based on an active shaft transverse vibration control concept that was theoretically analyzed in an earlier study and determined to be one of the most feasible methods. The system comprises of a piezoelectric stack actuator for applying control forces to the shaft via a rolling element-bearing, and a highly efficient, enhanced delayed-x LMS control algorithm to generate the appropriate control signals. To avoid the aliasing effects of higher frequency signals and reduce the phase delay of conventional filters, a multi-rate minimum-phase low-pass digital filter is also integrated into the controller. The experimental results yield 8–13 dB attenuation in the gearbox housing vibration levels and correspondingly 5–8 dB reduction in measured gear whine noise levels at the first and second operating gear mesh frequencies.

A new timing chain with no chordal action

Chain drives in internal combustion engines frequently induce a disturbing noise, so-called whine noise. Basically, this noise is caused by the chordal action or polygon effect that originates from the periodically changing effective radius of the sprockets. In this article, SmartChain B.V. presents a new roller chain or bushing chain that entirely avoids the disturbing polygon effect. The concept was evaluated by AVL List GmbH, using the multibody dynamics software Tycon.