Powertrain Noise, Vibration, and Harshness (NVH) Technology

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Powertrain Noise, Vibration,
and Harshness (NVH) Technology
s diesel engine emissions
standards become more
stringent, engines will use multiple
combustion modes over the
operating range to achieve the
new emissions requirements.
Additionally, the regeneration of
aftertreatment devices may require
step changes in parameters such
as air/fuel ratio and exhaust gas
recirculation (EGR) flow.
Unfortunately, switching between
different combustion modes can
cause audible step changes.
Because consumers object to unexpected changes in engine noise, transitions
in engine operating modes must be transparent to drivers.
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Color maps generated during evaluation of various engine operating
parameters indicate the relative importance of resonances (straight
lines) and order related responses (curved lines).
Gasoline engines also face noise, vibration, and harshness (NVH)
challenges from sources such as direct-injection fuel systems.
Transmissions experience gear meshing noise, pump noise, and noise from
other sources.
Southwest Research Institute® (SwRI®) has equipped a state-of-the-art
semi-anechoic chamber to aid engine manufacturers in developing engines
with reduced noise and vibration, taking careful account of trade-offs with
other engine characteristics.
Test Chamber
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Sound pressure measurements on all sides of the source
Sound power measurements (total radiated acoustic energy)
Acoustic intensity from various areas and/or components for noise
source identification and ranking
Vibration measurement, including inputs to key components
Modal analysis
Operating deflection shapes
Test chamber dimensions are 7.2 m long x 4.4 m wide x 3.3 m high.
The cutoff frequency according to ISO 3744 is below 125 Hz.
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The semi-anechoic chamber features acoustic wedges spaced from a solid
wall to increase sound absorption, along with a solid floor surface for
precise measurement and evaluation of:
Both gasoline and diesel engines, as well as transmissions and
driveline components such as transfer cases, can be installed for
evaluation inside the test chamber.
Capabilities
Studies can be conducted on:
• Gear rattle
• Valve train clatter
• Air compressor noise
• Piston slap
• Pump noise
Complete services are available and include studies of:
• Transmissions
• Related components
D017588_9305
• Engines
• Drivelines
Microphones located throughout the chamber
capture noise data.
Quality Accomplishments
The Office of Automotive Engineering (OAE) at SwRI is certified to ISO 9001:2008, “Quality Management
Systems − Requirements,” accredited to ISO/IEC 17025:2005, “General Requirements for the Competence of
Testing and Calibration Laboratories,” and certified to ISO 14001:2004, “Environmental Management
Systems.” The OAE has also achieved Ford Tier 1 status for providing engineering services and the Engine,
Emissions and Vehicle Research Division has received the Ford Q1 Quality Award. In addition, the Petroleum
Products Research Department is a Nuclear Procurement Issues Committee (NUPIC)-approved laboratory
and the Fuels and Lubricants Research Division has maintained its status as an American Chemistry Council
(ACC)-approved laboratory.
Southwest Research Institute is an independent, nonprofit, applied
engineering and physical sciences research and development
organization using multidisciplinary approaches to problem solving.
The Institute occupies 1,200 acres in San Antonio, Texas, and
provides more than 2 million square feet of laboratories, test
facilities, workshops and offices for more than 3,200 employees
who perform contract work for industry and government clients.
We welcome your inquiries. For additional
information, please contact:
Tom Reinhart
Program Manager
NVH, Design and Development
Engine, Emissions and Vehicle Research Division
(210) 522-5876
[email protected]
Benefiting government, industry
and the public through innovative
science and technology
Equal Opportunity Employer M/F/D/V
Committed to Diversity in the Workplace
swri.org
powertrainnvh.swri.org
03-0801 JCN 238683 tp
Southwest Research Institute
6220 Culebra Road • P.O. Drawer 28510
San Antonio, Texas 78228-0510

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