1
Informal document No.
(37th GRB, 19 and 20 September 2002,
agenda item 2.1.)
Study on Pass-by Noise Testing Methods Incorporating
Urban Driving Conditions
Test method of N2 category
Transmitted by JAPAN
1. Introduction
In Japan, urban running conditions have been investigated by using
various types of road vehicles with different power to mass ratios, and new
acceleration noise test methods have been studied. These studies found that,
concerning N2 category vehicles, the noise levels measured by the test
methods did not correspond well with the noise levels generated by urban
running1),2).
Therefore, field measurements concerning urban running conditions and
the acceleration noise test according to the ISO proposal were performed by
using 4 vehicles of N2 category including a CNG vehicle. In this report, these
results are described.
2. Running conditions on urban roads
The running conditions were investigated by using 4 vehicles with
maximum payload from 2 tons to 4 tons (gross vehicle weight from 4 tons to 8
tons). Table 1 shows the specifications of the test vehicles used in this
investigation. Vehicle N2-B is a CNG vehicle and the others are diesel engine
vehicles.
Figure 1 shows the distribution of the cumulative frequency of the engine
speeds when the N2 category vehicles ran on the urban roads. The 95
percentile value of the cumulative frequency of each vehicle is between 0.67
S and 0.77 S (S : rated engine speed), and the average value is 0.71 S. Figure
2 shows the relationships between power to mass ratio and engine speed,
and between power to mass ratio and acceleration. In the figure, the data of
all vehicles including the data reported in the 36th GRB meeting are
indicated. The blue squares indicate the data of the N2 vehicles added at this
time. The engine speed and acceleration data of the N2 vehicles are almost
on the same curve as the vehicles in the other categories, and this fact also
corresponds to the CNG vehicle.
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3. Test method of N2 category based on the ISO proposal
In this study, as the representative values of the noise generated from
running vehicles on urban roads, the maximum noise levels in the start and
the acceleration running condition were adopted. The calculation method of
the maximum noise level has already been reported in the 35th GRB meeting.
Figure 3 shows the example of the estimation results of the vehicle speed,
the engine speed and the noise levels. From the results, the maximum noise
levels have been extracted.
The engine speed at line BB (the end of the acceleration period) described
in the ISO proposal is 0.65 S to 0.75 S for N2 category vehicles. In this study,
the engine speed of 0.71 S at line BB was adopted on the basis of the data
obtained from the urban road running. Table 2 shows the test method of each
proposal. To examine the relationship between the noise level in the
acceleration tests and that in the urban running, the acceleration noise test
was conducted on the test track by using 7 vehicles of the N2 category. Table
3 shows the specifications of the test vehicles.
Figure 4 shows the relationships between the noise levels measured by
the test methods and the maximum noise levels under the start and the
acceleration condition on urban roads. Figure (a) shows the results of ECE
R51/02 method, and Figure (b) shows those of the ISO proposal in which the
engine speed of 0.71S at line BB was adopted for N2 category vehicles. The
levels measured by the ECE R51/02 method show poor correspondence with
the maximum noise levels at the start and the acceleration running
condition on urban roads in all categories.
On the other hand, the noise levels measured by the ISO method show
good correspondence with the maximum noise levels on urban roads. In the
figure, the blue squares indicate the data of N2 category vehicles in which
the engine speeds at line BB have been adjusted to 0.71S. Therefore, this
method can be applied to the N2 vehicles as well as others.
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4. Conclusions
Noise test method of the N2 category vehicles was studied based on the
investigation result of the running conditions on urban roads. From the
results, the following conclusions have been obtained.
(1) For the N2 category vehicles, the average value of 95 percentile values of
the cumulative frequency distributions of the engine speeds on urban
roads was 0.71 S.
(2) The engine speed of 0.71 S at the line BB was introduced into the ISO
proposal. As a result, it was found that the noise levels measured by the
ISO test method show good correspondence with the maximum noise
levels at the start and the acceleration condition on urban roads.
(3) We therefore agree with the German/ISO proposal3) in which the engine
speed of 0.70 S to 0.74 S was adopted as engine speed at line BB.
(4) The German/ISO test method can be also applied to the CNG vehicle.
References
1) Informal document No.6, WP29/35thGRB, 2001
2) Informal document No.2, WP29/36thGRB, 2002
3) TRANS/WP.29/GRB/2002/4
10 July 2002
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Table 1
Test V ehicle
M edium com m ercialvehicle-1
(2t Truck)
M edium com m ercialvehicle-2
(2t Truck)
M edium com m ercialvehicle-3
(4t Truck)
M edium com m ercialvehicle-4
(4t Truck)
Vehicles used in urban running test
N o.
Engine
D isplace
m ent
(cc)
N 2-A
D iesel
4214
92 / 3200
5M /T
N 2-B
CNG
3907
88 / 3200
5M /T
N 2-C
D iesel
8226
154 / 2850
N 2-D
D iesel
8226
129 / 2800
M axim um pow er
(kW /rpm )
5
V ehicle
m ass
(t)
Loading
conditions
P ow er to
m ass ratio
(kW /t)
2.18
4.27
2.99
5.08
U nladen
R ated load
U nladen
R ated load
42.3
21.6
29.6
17.4
6M /T
8.50
R ated load
18.1
5A /T
3.76
7.89
U nladen
R ated load
34.3
16.3
Trans
m ission
100%
100%
95 %
90%
V ehicle N 2-A
80%
70%
60%
N 2-A (D iesel,6M /T)
(P /m :21.6 kW /t)
95 % value :0.68 S
50%
40%
30%
20%
10%
0%
90%
V ehicle N 2-C
80%
70%
60%
N2-C(Diesel,6M/T)
(P/m : 18.1 kW/ｔ)
95 % value : 0.67 S
50%
40%
30%
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
80%
70%
60%
50%
40%
30%
20%
20%
10%
10%
0%
0%
0.0
1.2
0.0
0.1
0.2
N orm alized Engine R otation Speed (N /S)
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
0.0
0.1
0.2
0.0
0.1
0.2
N orm alized Engine R otation Speed (N /S )
100%
95 %
90%
100%
95 %
90%
V ehicle N 2-B
80%
70%
60%
N 2-B (C N G ,5M /T)
(P /m :17.4 kW /t)
95 % value :0.71 S
50%
40%
30%
20%
90%
70%
60%
40%
30%
20%
10%
0%
0%
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
0.0
N orm alized Engine R otation Speed (N /S)
Figure 1
N 2-D (D iesel,5A /T)
(P /m :22.4 kW /t)
95 % value :0.77 S
50%
10%
0.0
100%
V ehicle N 2-D
80%
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
N orm alized Engine R otation Speed (N /S )
Cumulative frequency distributions of engine speed during acceleration
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Cumulative　Frequency,　%
Cumulative　Frequency,　%
Cumulative　Frequency,　%
Cumulative　Frequency,　%
Cumulative　Frequency,　%
Cumulative　Frequency,　%
100%
95 %
90%
1.0
1.1
1.2
80%
70%
60%
50%
40%
30%
20%
10%
0%
1.0
0.6
2.0
0.4
Japan(Regression
Curve of N95)
0.2
M 1(M T,A T)
M 1(C V T)
M 1(H ybrid)
N1
N2
N 2(C N G )
N3
2
0.8
Acceleration, m/s
TUV(N2&N3)
Engine speed, s
2.5
M 1(M T,A T)
M 1(C V T)
M 1(H ybrid)
N1
N2
N 2(C N G )
N3
1.5
Japan(Regression Curve
of A95 at 50km/h)
1.0
0.5
ACEA(N90)
ISO Proposal
0.0
0.0
0
25
50
75
100
125
150
175
P ow er to m ass ratio,kW /t
25
50
75
100
125
P ow er to m ass ratio,kW /t
(a) Engine Speed
Figure 2
0
(b) Acceleration
Engine speed and acceleration in urban running (The 95 percentile values)
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150
175
Vehicle speed, km/h
Engine speed, rpm
70
60
50
40
30
20
10
0
2500
2000
1500
1000
500
0
85
Noise level，dB(A)
M axim um noise level
80
3rd 4th
2nd
V ehicle noise
P ropulsion noise
Tyre/road noise
5th
6th
75
70
65
60
0
Figure 3
100
200
300
D istance，m
400
500
Estimation results of the vehicle speeds, the engine speeds
and the noise levels during the start and the acceleration
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Table 2
Outline of each test method
EC E R 51/02
IS O P roposal
This study
M edium and heavy vehicles
M edium and heavy vehicles
M edium vehicles
Full-throttle acceleration
Full-throttle acceleration
Full-throttle acceleration
Vehicle front and rear
Engine front
Engine front
Unladen
N2,N3: 50 x maximum power (kg)
(the extra loading is limited to
75% of the max. weight allowed
for the rear axle)
M2,M3: unladen weight + 75kg
A cceleration
start
Vehicle front: AA' line
Engine front: AA' line
Engine front: AA' line
A cceleration
end
Vehicle rear: BB' line
Engine front: DD' line
(15m behind microphone)
Engine front: DD' line
(15m behind microphone)
D riving
m ethod
R eference
point
Loading
conditions
A pproach
speed
(V A )
N2: 50 x maximum power (kg)
(the extra loading is limited to
75% of the max. weight allowed
for the rear axle)
M2: unladen weight + 75kg
50km/h or 0.75S, whichever is less
V ehicle speed
at B B ’line
(V B )
Engine speed
at B B ’line
(N B )
G ear
selection
When power is less than 225kW,
n/2 or higher gear.
When power is more than 225kW,
n/3 or higher gear
(ｎ: total number of gears)
R eported
values
(L R )
LR= measured value
Medium vehicles(N2,M2)
NB: 0.65S-0.75S
Heavy vehicles(N3,M3)
NB: 0.85S-0.89S
NB: 0.71S
Gear nearest 35km/h at 0.65S
(N2,M2), 0.85S (N3,M3)
When gear is more than 5km/h off
target speed: two gears on either
side of 35km/h
When approach engine rotation
speed is less than 1000rpm:
higher gear
Gear nearest 35km/h at 0.71S
When gear is more than 5km/h off
target speed: two gears on either
side of 35km/h
When approach engine rotation
speed is less than 1000rpm:
higher gear
LR= measured value
When measurement is taken in
two gears: LR=(L1+L2)/2
LR= measured value
When measurement is taken in
two gears: LR=(L1+L2)/2
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Table 3
N o.
C ategory
N 2-1
D iesel
N 2-2
D iesel
N 2-3
N 2-4
N 2-5
N 2-6
N 2-7
Engine
type
D iesel
N2
D iesel
CNG
D iesel
D iesel
Vehicles used in the acceleration tests
D isplacem ent M axim um pow er
(kW /rpm )
(cc)
4104
4334
5249
6925
3907
4104
8226
91.9 / 3200
90.5 / 3100
103.0 / 3200
177.0 / 2700
88.3 / 3200
91.9 / 3200
128.7 / 2800
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Transm ission
V ehicle m ass
(m axim um
payload)
(kg)
5M /T
2170
(2000)
5M /T
5M /Ｔ
6M /T
5M /T
5M /T
5A /T
2610
(2000)
2582
(2000)
3630
(4100)
2910
(2000)
2100
(2000)
3680
(4100)
Loading
conditions
P ow er to m ass
ratio
(kW /t)
U nladen
41.0
50 x m axim um
pow er (kW )
21.2
U nladen
18.7
50 x m axim um
pow er (kW )
20.0
U nladen
38.8
50 x m axim um
pow er (kW )
21.7
U nladen
47.8
50 x m axim um
pow er (kW )
22.4
U nladen
29.6
50 x m axim um
pow er (kW )
20.0
U nladen
42.3
50 x m axim um
pow er (kW )
21.6
U nladen
47.8
50 x m axim um
pow er (kW )
22.4
90
90
IS O P roposal
N 2 :0.71S
EC E R 51/02
85
Noise level, dB(A)
Noise level, dB(A)
85
80
75
M 1(M T&A T)
M 1(C V T)
M 1(H ybrid)
N1
N2
N 2(C N G )
N3
M3
70
65
80
75
M 1(M T&A T)
M 1(C V T)
M 1(H ybrid)
N1
N2
N 2(C N G )
N3
M3
70
65
60
60
60
65
70
75
80
85
N oise levelduring start-acceleration，dB (A )
(m axim um noise levelw hen accelerating
from 0 - 60km /h)
90
65
70
75
80
85
N oise levelduring start-acceleration，dB (A )
(m axim um noise levelw hen accelerating
from 0 - 60km /h)
(b) ISO Proposal (N2 : 0.71S)
(a) ECE R51/02
Figure 4
60
Relationships between the noise levels measured by the test methods and the maximum noise level
under the start and the acceleration condition
11
90