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Model Verification of CAE with NVH-test Acting on Downsized Car Engines

Automotive Powertrain CAE NVH-Urban Rönnqvist
NVH-testing Powertrain-Janos Ribarits
  • Technical Paper
  • 2019-01-1550
To be published on 2019-06-05 by SAE International in United States
Today’s trend of downsized internal combustion engine development for cars is characterized with; high torque, low engine speed, low weight, high degree of cyclic irregularity, low excitation frequency due to fewer cylinders active e.g. 4-cylinder or less. Torque output 100 Nm at low engine speed 1000 rpm has become normal. This implies in respect of vibrations that it is important to control engine suspension rigid body modes e.g. roll yaw and pith ones. The rigid body modes frequencies should be low so they cannot be reached and induced by the low exciting harmonics of cylinder pressure and mass forces for low engine speeds or idling. Crucial is the rigid body modes in relation to the excitation forces. It is also important to control the overall flexible vibration modes. Our purpose is to describe the method to optimize the powertrain suspension, beginning with modeling/simulation and ending with verifying the vibration level on a real running engine i.e. a Volvo Cars in-line 4-cylinder VEA diesel engine in a test rig/cell. As a method a mathematical CAE model…
 

Developing a Custom Data Acquisition Software Package for a Self-contained Acoustic Testing Facility

Kolano and Saha Engineers Inc-Sagar Patil, Pranab Saha
Kolano and Saha Engineers Inc.-Richard Kolano
  • Technical Paper
  • 2019-01-1501
To be published on 2019-06-05 by SAE International in United States
This paper provides an overview of custom software developed for the sound generation, control and data acquisition of a self-contained acoustic testing facility system used for conducting random incidence sound absorption tests and sound transmission loss tests on small samples in accordance with SAE J2883 and J1400 standards, respectively. The paper discusses the thoughts behind developing user friendly algorithms and graphical user interfaces (GUI) for sound generation, control, data acquisition, and signal processing to obtain good data and precautions should there be any anomalies in the data.
 

Target Development for Transmission and E-Motor NVH

FEV North America, Inc.-Todd Tousignant, Alex Ford, Kiran Govindswamy
Ford Motor Company-Justin Dech, Frederick Vanhaaften, Matthew Hettenhouse
  • Technical Paper
  • 2019-01-1554
To be published on 2019-06-05 by SAE International in United States
It is a common practice to conduct NVH fingerprinting and benchmarking assessments at the powertrain level, to understand source level noise and vibration. To assess the NVH influence of engine, e-motor, and transmission, sub-system testing is often con-ducted in addition to full powertrain testing. These powertrain or sub-system investiga-tions provide valuable information regarding the status of “source” level excitations rela-tive to targets and / or competitive powertrains. In the case of transmissions and e-machines, it is particularly important to understand source level tonal content and how this will be perceived at the vehicle level. However, variation in component design re-sults in differences in order content, which complicates the process of objectively com-paring multiple products. Multiple methods are presented here for characterizing tonal content of transmission and e-machines, based on assessments conducted in a component hemi-anechoic dy-namometer test cell. Ultimately, sound quality is assessed, by the customer, at the ve-hicle level. Accordingly, the methods developed incorporate means of cascading re-sults between component level and vehicle level. Furthermore, since the perception of tonal content is dependent upon…
 

Truck front cabin mount tuning for cabin Noise boom elimination and overall interior noise reduction.

VE Commercial Vehicles Ltd-Sourabh Jadhav
VE Commercial Vehicles, Ltd.-Saahil Saxena
  • Technical Paper
  • 2019-01-1513
To be published on 2019-06-05 by SAE International in United States
In today's automobile industry refined NVH performance is a key feature and of high importance governing occupant comfort and overall quality impression of vehicle. This paper interior noise measurement is done on one of the light truck and few dominant low frequency noise booms were observed in operation range. Modal analysis was done for the cabin at virtual as well as experimental level and few modes were found close to these noise booms. Vibrations were measured across the various cabin mounts and it was found that the isolation of front mounts is not effective at lower boom frequencies. Taking this as an input, the mount hardness and profile optimized to shift the natural frequency and hence improve the isolation behavior at the lowest dominant boom frequency. This was followed by static and dynamic measurement of the mounts at test rig level and finally the interior noise measurement after fitment on truck. Boom elimination and overall interior noise reduction is achieved with this approach. This paper takes up a real-time noise scenario , its root cause…
 

Research on active noise control method on the reduction of drivetrain noise from a heavy off-road vehicle

Dongfeng Motor Technical Center-zuguo xia
Gissing Tech Co Ltd-Wei Huang, Longchen Li, Xiaojun Chen, Xiujie Tian, Keda Zhu, Changwei Zheng, Jiapeng Zhao, Renjie Dai
  • Technical Paper
  • 2019-01-1566
To be published on 2019-06-05 by SAE International in United States
Drivetrain noise from heavy off-road vehicles mainly includes engine noise, drive shaft noise, wheel-side gear noise, tire pattern noise etc. They are the main noise source for such vehicles as they greatly influence the ride comfort of the passengers inside. This paper solved the drivetrain noise problem of a heavy off-road vehicle using the method of active noise control. Firstly, the vehicle is benchmarked and the noise problems are analyzed, while the noise sources are identified by analyzing the transmission principles of the drivetrain; secondly, active noise control strategies are made for the vehicle based on the noise profiles under various operating conditions; thirdly, the multiple parameters for active noise control are computed from simulations modeling the vehicle in idle, constant speed and acceleration respectively; lastly, road tests are conducted using the multiple parameters from the simulations and a noise reduction of 2-4 dB can be achieved in the whole vehicle. The results has shown that active noise control is an effective method for drivetrain noise reduction in heavy off-road vehicles as this paper provides…
 

A Case Study on Golf Car Powertrain NVH Sources and Mitigation Methods

Club Car, LLC-Adam Clark
Roush Industries Inc-Steven Carter, Kenneth Buczek, Mayuresh Pathak
  • Technical Paper
  • 2019-01-1478
To be published on 2019-06-05 by SAE International in United States
Throughout North America the golf market has remained nominally flat in recent history and has grown worldwide. With this growth a trend has been seen where the number of young adults as well as adults over the age of 65 years involved with the game has increased. The demographics in golf showing the most growth also have high standards for the operation of the golf car and have transcended their expectations to align with some of the qualities expected of automobiles. These shifts in consumer expectations along with market competition drive OEMs to deliver refined golf cars making noise and vibration a key aspect in development. This paper showcases a recent study to improve the powertrain N&V performance of an I.C. engine golf car. Primarily, a test-based approach was followed. Chassis rolls and on road testing were performed for vehicle benchmarking and target setting. System and component tests were completed to identify root cause and provide input to mitigation methods applied. Structural modifications were applied to reduce structure-borne noise and perceived vibration. Component modifications and…
 

Development of a Muffler Insertion Loss Flow Rig

University of Kentucky-Jonathan Chen, D. W. Herrin
  • Technical Paper
  • 2019-01-1482
To be published on 2019-06-05 by SAE International in United States
Mufflers and silencers are commonly used to attenuate noise sources such as internal combustion engines and HVAC systems. Though the transmission loss of a muffler sans flow is relatively simple to obtain using the two-load method, the presence of mean flow modifies the muffler behavior. The development of an insertion loss test rig is detailed. A blower produces the flow and an upstream silencer quiets the flow before it enters the muffler. Loudspeakers are positioned just downstream of the silencer and they are used as the sound source. The measurement platform allows for the measurement of flow-induced noise in the muffler. In addition, the insertion loss of the muffler can be determined, and this capability was validated by comparison to a one-dimensional plane wave model.
 

On the Measurement and Simulation of Flow-Acoustic Sound Propagation in Turbochargers

FEV Europe GmbH-Ralf Stienen
Institute for Combustion Engines, RWTH Aachen University-Hendrik Ruppert, Felix Falke, Stefan Pischinger, Marco Günther
  • Technical Paper
  • 2019-01-1488
To be published on 2019-06-05 by SAE International in United States
Internal combustion engines are increasingly being equipped with turbochargers to increase performance and reduce fuel consumption and emissions. Being part of exhaust and intake systems, the turbocharger strongly influences the orifice noise emission. Although 1D-CFD simulations are commonly used for the development of intake and exhaust systems, validated acoustic turbocharger models are not yet state-of-the-art. Consequently, the first aim of the paper is the investigation of the influence on the orifice noise and the development of an accurate 1D-CFD model. Firstly, active and passive acoustics of turbochargers are distinguished. Complex active turbocharger noise emissions were investigated on a turbocharger test rig and could be correlated with unstable rotating stall. Therefore critical acoustic operation can be identified in early engine development stages by comparison to other tested turbochargers. The passive acoustic transmission loss was measured for a wide operating range of four turbochargers, including wastegate and VTG-system variations. Low frequency attenuation is dominated by impedance discontinuities, increasing considerably with mass flow and pressure ratio. High frequencies are determined by destructive interference in the stator. A new…
 

Test and Analysis of Electromagnetic Noise of an Electric Motor in a Pure Electric Car

Geely Automobile Research Institute-Perry Gu, Chao Gong
Geely Automoile Research Institute-Qiang kang
  • Technical Paper
  • 2019-01-1492
To be published on 2019-06-05 by SAE International in United States
Compared with the low-frequency ignition order of mechanical and combustion noise of the internal combustion engine, the electric drive assembly noise of electric vehicles is mainly the high-frequency whining order noise generated by the electromagnetic force and gear meshing, as well as the high-frequency umbrella noise generated by DC/AC pulse width modulation. Although the radiated sound power is far less than that of an internal combustion engine, the high frequency noise of the motor and the reducer is also annoying. In this paper, the main characteristics of the vibration and noise of an electric motor are obtained by testing it on the vehicle and on the test rig. The main frequency orders are multiplies of motor poles, of which the most significant is the 48th order. The deformation of the motor at the resonance frequency of the 48th order is the breathing mode. Through analysis of electromagnetic force wave, the sources of main orders of motor noise are explained. The most significant order 48th comes from the interaction between rotor magnetic field and stator slots.…
 

Fast accurate non-destructive measurement of absorber impedance and absorption

3M-Jon Alexander
Bruel & Kjaer S&V Measurement A/S-Jason Kunio, Flemming Larsen
  • Technical Paper
  • 2019-01-1584
To be published on 2019-06-05 by SAE International in United States
Cabin acoustic comfort is a major contributor to the potential sales success of new aircraft, cars, trucks, and trains. Recent design challenges have included the increased use of composites, and the switch to electrically powered vehicles, each of which change the interior noise spectral content and level. The role of acoustic absorption in cabins is key to the optimisation of cabin acoustic comfort for modern vehicles, with acoustic impedance data needed in order to assess and optimise the impact of each component of a given lay-up. Measurements of absorbing interior trim are traditionally performed using either sample holder tests in a static impedance tube (impedance and absorption), or through tests in reverberation rooms (absorption only). Both of these procedures present challenges. In-tube absorption and impedance measurements are destructive, requiring highly accurate sample cutting and sealing. Reverberation room absorption measurements are subject to the effects of varying room diffusion, along with the impact of edge diffraction, sample geometry, and location. Finally, while non-destructive methods using hand-held probes also measure absorption, they are not able to measure…