Powertrain NVH Development Active Noise Control by Piezo Technology

The long-standing dream of NVH engineers to reduce

powertrain structure-borne noise radiation by Active Noise

Control is close to becoming reality. FEV’s NVH research

results indicate – as an example - that piezo-electric foil

technology offers a significant noise emission reduction po-

tential for the oil pan.

Today’s powertrain NVH development focuses on the re-

duction of noise excitation, the optimization of structure-

borne noise introduction and transmission as well as on

the reduction of noise radiation by the components’ outer

surfaces. Typically, the oil pan represents the major power-

train structure-borne noise source resulting from e.g. the

powertrain concept (structural oil pan to support global

powertrain stiffness), size (especially in truck application),

material properties and design (reduced wall thickness,

large density of natural oscillations in the noise relevant

frequency range) etc.

Typical Powertrain

Sound Power Distribution

Besides structural optimization, further noise reduction po-

tential can be utilized by the application of piezo-electric-

foil based Active Noise Control. This approach uses the

piezo-electric principle: The piezo-electric crystal changes

its shape according to an externally applied voltage.

Piezo-Electric Foil

Active Noise Control is achieved by the “synchronization”

of the piezo activation with the vibration excitation of the oil

pan outer surface. A well-balanced phase shift between oil

pan and piezo-electric foil vibration amplitude results in a

significant reduction of oil pan wall vibrations, i.e. oil pan

structure-borne noise emission.

Structure-Borne Noise Reduction by Active Noise Control

Piezo-electric foil application is supported by FEA/MBS

simulation which yields noise relevant oil pan natural oscil-

lations as well as appropriate foil locations. The complete

Active Noise Control system will consist of a vibration sen-

sor (reference signal), a piezo-electric actuator (foil,

stack …) and a control unit. FEV will continue to pursue

this promising approach regarding vehicle, truck, industrial

machine and locomotive application.

CONTACT: Dr.-Ing. Norbert Alt

FEV Motorentechnik

Neuenhofstrasse 181

52078 Aachen, Germany

Phone: (+49)241 5689-419

Fax: (+49)241 5689-119

Email: alt@fev.de

http:// www.fev.com

Oil pan

Residual

Components

Oil pan

Residual

Components

1000 2000 3000 4000 5000 600070

80

90

100

110

120

Baseline

Piezo Activated

Baseline

Piezo Activated

up to 20 dB

Noise Level

Reduction

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speed [rpm]