1.1.5-6
CS35 2013.04
1.1.5-6Noise, Vibration and Harshness
engine rigidity (no gaps at the bracket connec-
tion).
Simple prob
lem tesing:
•
R
emove a
ll suspe
n
sion bushin
g
s in
exhaust syste
m
.
•
S
uspect
e
x
hau
st system with rope
(a
t
most two
suspension p
o
int
s
).
•
I
nspect th
e no
ise
le
vel of
cab
in
road
testing.
•
If the noise is eliminated
,
it
means
the
exhaust bushing
is noise source
.
• Take road testing after installing every
bushing and check noise level.
•
B
ased on this procedure
,
the bushing
causing no
ise
will
be fou
nd out.
Body
Function
•
The
requiremen
t
to ve
hicle is allround
,
especially the vehicle in driving. Here,
what we emphasize are other main
components that cause noise in vehicle,
such a
s
eng
ine a
nd bushing
. The vehicle
body is one of the most important part
involving NVH.
• The components we described here only
mean the the
comp
onent
s to cause
vibration and noise based on function
V
ehicle
b
ody in
clu
des or co
ncern
s
all
the
s
e comp
onent
s.
•
The
vehicle bod
y not only causes air
noise,
but also c
auses solid noise.
•
V
ehicle bod
y must
abso
r
b the
vib
r
ation
from all components and try to stop
tran
smittin
g
the vibra
t
ion
to the vehicle
body.
• The main components of NVH in the
vehicle bod
y are the roof
steel
p
l
ate, the
side wall and the floor. The vibration or
noise shall be increased greatly due to
the
strut
c
ture,
just as
an amplifier
.
Higher Requirement
s for V
e
hicle Body
•
G
ood f
alling or
knock p
e
rformance
• Spacious interior
• Corrosion resistance
• Light weight
• Excellent aerodynamic appearance
Becau
s
e can not satisfy a
ll th
ese re
quire
ment
s
a
t
the same
time
, we only ad
opt a h
a
lf-way solution
.
For example, to satisfy NVH performance, the
integral rigidity of vehcile body must be ensured
together with the good resiliency in crash and with
cert
ain
flexibility
of ve
hicle body
. So we
on
ly ca
n
adopt
the me
thod of
crumpling or twist p
a
rtial
areas.
Example:
The ensuran
ce of veh
i
cle body
water proo
f
can not ensure the requirements to noise and
vibration at the
same time, so
the followin
g
ele
m
en
t
s
sho
u
ld b
e
con
s
id
ered:
• Correctly install the vehicle window.
• Correctly install the sealing strip.
Other precautions:
• All pipes to engine compartment.
•
D
oor
and win
dow sea
ling
strip.
•
H
eate
r
and vent.
• Sunroof drain pipe.
The cr
oss
component
s
o
f
sid
e
wa
ll an
d vehicle
body are usually the transmitted passage to vibra-
tion
and no
ise
,
possib
l
e rectificat
ion method
s are
.
• Install at seperated positions at critical
localisation
s (such as A
p
illar
a
nd sid
e
wall)in or
der to reach the goo
d soun
d
insulation performance.
CAUTION: The foam block or foam filled
b
l
oc
k i
s
a
go
od
so
und
in
su
latio
n
m
eas
ure.
If the noise occurs in wind, tire, engine or
road surfac
e
, che
ck the fo
am bloc
k at the
relative
positions.
• Install foam block at influenced area.
•
Fil
l
fo
a
m
blo
c
k at
th
e re
la
ti
ve
ga
ps
or
holes.
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