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Personal Vehicles With Auto-Body Shielding of the Drive Assembly-External Noise Reduction and Internal Noise
Sector:
Language:
German
Abstract
An efficient method for the reduction of vehicle noise is to
close the engine compartment in a soundtight manner. By this means,
the sound radiation from the power unit, which has main influence
on the vehicle's exterior noise, can be reduced in an economic
way. Furthermore, the increased suppression on the impulsive high
frequency noise is subjectively recognized as an additional
advantage. However, a large scale use of an encapsulation demands
for proper cooling of the engine and, with respect to interior
noise, a deterioration of passenger comfort must be avoided.
In two different vehicles three kinds of engine enclosures have
been tested. It is demonstrated that thermal problems within the
enclosure can be avoided by an appropriate design. In addition,
with some development of the cooling system, sufficient cooling
rate can be provided. Concerning the passenger compartment, it is
an intrinsic advantage of the enclosure that there is almost no
noise to be radiated downwards onto the road and reflected back
into the vehicle. Thus, it is not only possible to avoid
disadvantages with respect to interior noise, but with some effort
even the noise levels within the passenger compartment can be
reduced