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Design & Development of Partial Engine Encapsulation for Interior Noise Reduction in Commercial Vehicles

VE Commercial Vehicles Ltd-Sourabh Jadhav
VE Commercial Vehicles Ltd.-Yadhu S. Aswan
  • Technical Paper
  • 2019-01-1589
To be published on 2019-06-05 by SAE International in United States
This paper focuses on partial encapsulation technique for reducing air-borne noise from the rocker cover of a commercial vehicle diesel engine. Due to increasing awareness, customers demand for improvised NVH-Noise Vibration and Harshness performance in modern day vehicles. Better NVH performance implies better comfort for passengers as well as vehicle operator. This further increases the driver up time due to reduced driver fatigue. In order to improve NVH performance of existing vehicle and observe different noise and vibration zones, detailed noise and vibration mapping was carried out on one of our vehicle platform. It is observed that engine noise is one of the major contributors for interior noise, apart from road inputs etc. There are well established methods to reduce the inherent noise of the engine, but the same might affect other performance parameters including fuel efficiency and exhaust emissions, which are pain areas of major automotive industries due to stringent homologation norms. Engine top area partial encapsulation with barrier cover is designed considering various integration as well as heat load constraints at vehicle level.…
 

Optimal Pressure Relief Groove Geometry for Improved NVH Performance of Variable Displacement Oil Pumps

Ford Motor Company-Abdelkrim Zouani, vidya Marri
  • Technical Paper
  • 2019-01-1548
To be published on 2019-06-05 by SAE International in United States
Variable Displacement Oil Pump (VDOP) is becoming the design of choice for engine friction reduction and fuel economy improvement. Unfortunately, this pump creates excessive pressure ripples, at the outlet port during oil pump shaft rotation, causing oscillating forces within the lubrication system and leading to the generation of objectionable tonal noises and vibrations. In order to minimize the level of noise, different vanes spacing and porting geometries are used. This paper presents an optimization method to identify the best geometry of the oil pressure relief groove. The method integrates adaptive meshing, 3D CFD simulation, Matlab routine and Genetic Algorithm based optimization. The genetic algorithm is used to create the required design space in order to perform a multi-objective optimization using a large number of parameterized groove geometries. Results of this optimization method are discussed and a design guideline for the oil pressure relief groove is disclosed.
 

Towards a quiet vehicle cabin through digitalization of HVAC systems and subsystems aeroacoustics testing and design

Dassault Systemes SIMULIA-Vincent Vidal, Adrien Mann, Jonas Verriere, Minsuk Kim
Valeo Thermal Systems-Fabrice Ailloud, Manuel Henner, Olivier Cheriaux
  • Technical Paper
  • 2019-01-1476
To be published on 2019-06-05 by SAE International in United States
With the rise of electric autonomous vehicles, it has become clear that the cabin of tomorrow will drastically evolve to both improve ride experience and reduce energy consumption. In addition, autonomy will change the transportation paradigm, leading to a reinvention of the cabin seating layout which will add pressure on climate systems team to design quiet and energy efficient systems. Consequently, Heat and Ventilation Air Conditioning (HVAC) systems designers have to deliver products which performs acoustically better than before, but often with less development time. To success under such constraints, designers need access to methods providing both assessment of the system (or subsystems) acoustic performance, and identification of where the designs need to be improve to reduce noise levels. Such methods are often needed before a physical prototype is requested, and thus can only be achieved in a timely manner through digital testing. Previous studies have demonstrated the ability of a CFD/CAA approach based on the Lattice Boltzmann Method (LBM) to predict HVAC system noise including real and complex ducts, registers, mixing unit and blower…
 

Mitigation of Community Noise from a Vacuum Excavator using Simulations

Charles Machine Works-Vernon Stellman, Craig Clevenger, Jeff Smith
Dassault Systemes Simulia Corp-Rahul Sanal, Karthik Mahadevan Muthuraman, Robert Powell
  • Technical Paper
  • 2019-01-1480
To be published on 2019-06-05 by SAE International in United States
Off-highway equipment operates in residential communities and must meet their radiated noise targets to be compliant with noise regulations and to be competitive in the marketplace. Traditional find and fix noise testing of late-stage prototype designs may cause launch delays, with intense time pressures that often result in missed opportunities to create excellent products with good value. Accurate simulation of noise from these machines allows noise targets to be assessed at each stage of product development, giving engineers time to develop low noise products without adding excessive manufacturing cost. Simulation of an early prototype of a new vacuum excavator showed excessive levels of radiated noise in two different frequency ranges. Further investigation of the simulation results of these two spectrum ranges indicated different noise mechanisms producing the excessive noise levels. An acoustic resonance was excited in the exhaust flow downstream of a silencer by highly vortical flow through a ninety-degree elbow. Broadband flow noise was also being generated downstream of this silencer, in a higher frequency range. Solutions to the two separate noise issues were…
 

Effect of Optimal Hypoid Gear Tooth Profile Modifications on Vehicle Axle System Dynamics

Chongqing University-Shouli SUN
Chongqing University of Technology-Weiqing Zhang
  • Technical Paper
  • 2019-01-1527
To be published on 2019-06-05 by SAE International in United States
The vehicle axle gear whine noise and vibration are key issues for the automotive industry to design a quiet, reliable driveline system. The main source of excitation for this vibration energy comes from hypoid gear transmission error (TE) and transmits through the flexible axle components, then radiates off from the surface of the housing structure. Thus, the design of hypoid gear pair with minimization of transmission error is one way to improve the dynamic behavior of the vehicle axle system. In this study, an approach to obtain minimum transmission error and improved dynamic response with optimal tooth profile modification parameters is discussed. A neural network algorithm, named Back Propagation (BP) algorithm, with improved Particle Swarm Optimization (PSO) is used to predict the transmission error if some tooth profile modification parameters are given to train the model. With the optimal Hypoid gear tooth profile modification, a system level analysis of vehicle axle system is performed to verify the improvement on dynamic response aiming at minimizing the transmission error. A case study of a Hypoid gear pair…
 

A Comparison of Near-Field Acoustical Holography Methods Applied to Noise Source Identification

Purdue University-Tongyang Shi, J Stuart Bolton
  • Technical Paper
  • 2019-01-1533
To be published on 2019-06-05 by SAE International in United States
Near-field Acoustical Holography (NAH) is an inverse process, in which sound pressure measurements made in the near-field of an unknow sound source can be used to reconstruct the sound field so that source locations to be clearly identified. NAH was originally based on performing spatial transforms of arrays of measured pressures and then processing the data in the wavenumber domain, a procedure that entailed the use of very large microphone arrays to avoid spatial truncation effects. Over the last twenty years, a number of different NAH methods have been proposed that can reduce or avoid spatial truncation issues: for example, Statistically Optimized Near-field Acoustical Holography (SONAH), various Equivalent Source Methods (ESM), etc. Then, more recently, with the motivation of facilitating the measurement process, the principles of Compressive Sensing (CS) have been introduced in several studies to allow sound fields to be reconstructed based on a relatively small number of microphone measurements (thus making holographic measurements more practical and inexpensive), and these studies have shown promising results when used to identify sound source locations. In the…
 

Testing Methods and Signal Processing Strategies for Automatic Transmission Transient Multiplexed Pressure Data

Ford Motor Company-Steve Frait, Ram Sudarsan Devendran
Michigan Technological Univ-Mark Woodland, Jason Blough, Darrell Robinette, Carl Anderson
  • Technical Paper
  • 2019-01-1500
To be published on 2019-06-05 by SAE International in United States
This paper covers the development of test cell hardware, testing procedures, and signal processing to capture and transform transient multiplex pressure data from multiple data acquisition for a highly instrumented 6 speed automatic transmission with a torque converter. A total of 37 pressure transducers were installed in the transmission, with 8 being on several clutches, valve bodies, and other various locations. The remaining 29 transducers were instrumented in the torque converter and transmitted signals via three telemetry transmitters. Each transmitter had the capability of handling 7 or 15 channels. The transmitters multiplexed through the channels in intervals of approximately 1 second. Due to the complexity of the instrumentation, a dyno controller, transmission controller, data acquisition system, and three telemetry receivers were used and synchronized. To accommodate for the multiplexed data a varying time trigger and repetitive testing conditions were designed and used to repeat the transient event on each of the channels. After completing the tests, the data is post processed to split the multiplexed data into individual channels, calibrated, stitched back together, and realigned…
 

Improved measurement procedures for engine noise reduction with advanced microphones

GRAS Sound & Vibration-Jan Hansen, Per Rasmussen
  • Technical Paper
  • 2019-01-1463
To be published on 2019-06-05 by SAE International in United States
Introducing a new transducer concept has resulted in considerable reduction in setup time and at the same time improved accuracy and repeatability for engine bay noise transfer studies. The acoustic environment inside cars are one of the primary comfort parameters. This is made up of a number of contributions from drivetrain, auxiliary equipment, wind noise and tire noise, and all are influenced by the transfer from the source to the receiver. With the change from purely internal combustion engines to electrical or electrical assisted propulsion systems, a new set of noise sources are introduced in the engine compartment and this requires renewed focus on the transmission paths to the receivers inside the car cabin. Typically, one of the tools to study these mechanisms is by using a reverse transmission technique, placing a well-defined sound source in the receiver position inside the car and measure the resulting sound pressure levels in the engine compartment. Assuming reciprocity, these measurements can be used to estimate the attenuation of transmission from sound sources in the engine compartment to the…
 

Reducing vehicle interior NVH by means of locally resonant metamaterial patches on a rear shock tower

KU Leuven - DMMS lab, Flanders Make-Luca Sangiuliano, Claus Claeys, Elke Deckers PhD, Bert Pluymers, Wim Desmet PhD
MotionS lab, Flanders Make-Jasper De Smet
  • Technical Paper
  • 2019-01-1502
To be published on 2019-06-05 by SAE International in United States
Stringent regulations for CO2 emissions and noise pollution reduction demand lighter and improved NVH solutions in automotive industries. Designing light, compact and, at the same time, improved NVH solutions is often a challenge, as low noise and vibration levels often require heavy and bulky additions, especially to be effective in the low frequency regime. Recently, locally resonant metamaterials have emerged among the novel NVH solutions because of their performant NVH properties combined with lightweight and compact design. Thanks to stop band behavior, metamaterials beat the mass law, be it at least in some tunable frequency ranges. Previously the authors demonstrated how metamaterials can reduce the vibrations in a simplified shock tower upon shaker excitation. In this work, the authors apply the metamaterial concept on a real shock tower of a vehicle. As benchmark, a vehicle is chosen which has a 1.46 kg weight addition in the form of a lumped tuned vibration absorbers on each of the rear shock towers as NVH solution. It is shown that the metamaterial solution allows to achieve similar interior…
 

Wind Noise Transmission Loss for Separated Flow Conditions

Calvin Engineering-Richard DeJong
Toyota Motor North America Inc-Steve Sorenson
  • Technical Paper
  • 2019-01-1469
To be published on 2019-06-05 by SAE International in United States
The transmission of turbulent flow pressures through panels to the interior noise depends on the spatial matching of the pressure and vibration fields. Since the exterior pressure field on a moving vehicle includes both turbulent pressure and acoustic pressure, both need to be factored into a noise transmission loss calculation. However, these two exterior pressure fields have very different spatial patterns. This is further complicated when the exterior flow is separated from the surface due to an obstruction. This study uses wind tunnel and road tests to measure and model the wind noise transmission loss through the side glass of a vehicle. The results are seen to be very different from the traditional sound transmission loss curves for an acoustic pressure source.