UN-R41.04 ASEP
Overview
ASEP overview
◆Overview of the regulation
- To assess the amount of change in WOT noise relative to
the engine speed.
- The criterion are below the linear slope of 5 dB/1,000 rpm
for higher engine speeds and 0* dB/ 1,000 rpm for lower
Full-throttle noise value dB
Test result image
<Non-conformance area>
5dB/1000rpm slope
0dB/1000rpm slope
Regulatory value
Upper
<Conformance area> 3dB
limit point
Reference point
Lower limit point
0 Engine revolutions in front of
microphone nPP’
(*1dB from 2017)
engine speeds in relation to the reference point +3 dB.
- The regulation applies to Class III (PMR>50) only.
◆Reference point
-The same as Lwot at the time of measuring Lurban (in case of
measurement using the two gears, select the one for the
lower gear).
Test course overview
(Throttle fully
closed) B
P
B'
P'
Microphones
A'
A
(Wide open
throttle)
ASEP overview
- The vehicle speed nAA’ at point AA’ is adjusted so that the
engine speed nBB’ at point BB’ could satisfy the below and
WOT noise level is measured.
nBB’=0.85×（ｓ-nidle）+nidle (PMR≤66)
(However, VBB’≤80km/h)
s: rated engine speed
nidle: Enging speed at idle
Full-throttle noise value dB
Test result image
◆Upper limit point
<Non-conformance area>
5dB/1000rpm slope
0dB/1000rpm slope
Regulatory value
Upper
<Conformance area> 3dB
limit point
Reference point
Lower limit point
0 Engine revolutions in front of
microphone nPP’
nBB’=3.4×PMR-0.33（ｓ-nidle）+nidle (PMR>66)
Test course overview
The selected gear shall be 2nd. If the 3rd gear satisfies
requirements of nBB' and vBB',
3rd
shall be used. If the
4th
gear
satisfies requirements of nBB' and vBB', 4th shall be used.
◆Lower limit point
- The vehicle speed VAA’ is adjusted so that the engine speed nAA’
at point AA’ could satisfy the below the WOT noise level is measured.
nAA’=0.1×（s-nidle）+nidle
(However, VAA’≧20km/h)
No specification of gear selection for the measurement.
(Throttle fully
closed) B
P
B'
P'
Microphones
A'
A
(Wide open
throttle)
ASEP overview
◆Evaluation method of the final result
- Noise value is plotted against engine speed in front of
microphone nPP’.
- Measurement is required at least for the reference and
upper limit points; Additional test points are allowed.
- Criteria must be met at all points within the range from
lower to upper ASEP limit lines.
- If the change of nBB’ is limited to less than 0.05×（ｓ－
Full-throttle noise value dB
Test result image
<Non-conformance area>
5dB/1000rpm slope
0dB/1000rpm slope
Regulatory value
Upper
<Conformance area> 3dB
limit point
Reference point
Lower limit point
0 Engine revolutions in front of
microphone nPP’
Test course overview
(Throttle fully
closed) B
P
nidle) against the reference point, the ASEP does not apply
(in case of some CVT vehicles).
B'
P'
Microphones
A'
A
(Wide open
throttle)
ASEP control range
Example
vBB' < 80 km/h
nBB' < 0.85 * (S - nidle) + nidle (PMR < 66)
3.4 * PMR - 0.33 * (S - nidle) + nidle (PMR > 66)
1st
2nd
3rd
4th
5th
ASEP control range
nAA' > 0.1 * (S - nidle) + nidle
vAA' > 20 km/h
Limit
(shown by the graph)
Example
Line with slope
of 5dB/1000min-1
Lwot,(i)
Line with slope of
1dB/1000min-1 *
3dB
Reference point
full throttle acceleration test
･vPP’ = 50km/h
･the same gear(i) as tested
in Annex3
Any measurements shall be
within this area.
nwot,(i)
* 0dB/1000min-1 until the end of 2016
Example of ASEP measurement
Example of
ASEP measurement
G vehicle: MT model
Maximum output=29kW; vehicle weight=168 kg; PMR＝119.3; ｓ＝14000rpm; nidle＝1600rpm
Desk study results of test conditions
Upper limit point
Lower limit point
Gear
nBB’＝10300rpm
nAA’＝2840rpm
VBB’（km/h）
VAA’（km/h）
2nd
61.8
17.0
3rd
77.7
21.4
4th
93.8
25.9
◆Reference point
Third gear VPP’=50km/h (Lurban: Measured with third gear)
◆Upper limit point
nBB’=3.4×PMR-0.33（ｓ-nidle）+nidle =10300
It is expected that 3rd gear will be employed for the upper limit
VBB’≦80km/h
measurement and 4th gear for the lower limit.
◆Lower limit point
nAA’=0.1×（ｓ-nidle）+nidle =2840
Reference point test result
VAA’≧20km/h
Gear
Final test result
3rd
90
1
2
3
Average
L
76.1
76.8
76.7
76.5
R
77.6
76.8
77.2
77.2
L
82.7
81.9
82.7
82.4
Upper limit value test result
R
VAA’
VPP’
VBB’
81.9 65.9 71.8 77.9
82.7 66.4 71.9 77.9
82.2 67.0 72.8 78.1
82.3 66.4 72.2 78.0
nPP’
9443
9457
9575
9492
nBB’
10246
10246
10272
10254
L
70.7
70.7
70.8
70.7
Lower limit value test result
R
VAA’
VPP’
VBB’
71.1 26.3 34.0 39.9
70.8 26.2 33.8 39.7
71.1 25.9 34.2 40.1
71.0 26.1 34.0 39.9
nPP’
3706
3684
3728
3706
nAA’
2867
2856
2823
2848
Lwot （dB）
85
80
Gear
Regulatory value （～2016）
Upper limit point
3rd
Reference point
75
1
2
3
Average
VAA’
41.9
42.4
40.5
41.6
VPP’
50.1
50.7
49.2
50.0
VBB’
57.4
58.1
57.0
57.5
nPP’
6589
6668
6471
6576
Lower limit point
70
3000
4000
5000
6000
7000
8000
9000 10000
Gear
nPP' （rpm）
4th
1
2
3
Average
Example of ASEP measurement - If exemption provisions apply.
ASEP exemption:
If the variation of the exit engine speed nBB’ relative to the reference point is below 0.05×（ｓ－
nidle), then the ASEP does not apply.
Vehicle H: CVT model; Max. output = 37.7kW; Vehicle weight =250 kg; PMR＝116; ｓ＝7500rpm;
nidle=1300 rpm
8<Reference>
8
◆Reference point
VPP’=50km/h
◆Upper limit point
nBB’=3.4×PMR-0.33（ｓ-nidle）+nidle =5691
VBB’≦80km/h
◆Lower limit point
nAA’=0.1×（ｓ-nidle）+nidle =1920
VAA’≧20km/h
Lwot (dB）
全開騒音値　（dB ）
86
Referenc
e point
Lower
limit
84
83
Std.
Lower limit point
82
81
Reference point
Upper limit point
80
79
Test result
Upper
limit
85
78
4000
Vehicle speed （km/h）
Final test result
87
Engine speed （rpm）
4500
Noise(dB)
Condition
VAA’
VPP’
VBB’
Condition
nAA’
nPP’
nBB’
L
R
VBB’≦80
72.5
75.4
80.0
nBB’≦5691
3879
4585
4810
78.3
79.3
－
41.6
50.0
60.1
－
3112
4437
4804
77.5
80.2
VAA’≧20
20.0
40.6
56.2
nAA’≧1920
2379
5094
5112
80.6
82,3
5000
nPP'　（rpm ）
5500
6000
nPP’ (rpm）
Differences from the value at reference
point nBB’ 4,804 rpm are below “0.05×（snidle）=310rpm” for both upper and lower
limits, and therefore the exemption
applies.
As it is unable to adjust the engine speed, measurements
are made at VAA’=20km/h and VBB’=80km/h.
Questions or comments can be addressed to Daniela Leveratto,
IMMA Technical Director, at the following email:
[email protected]
Thank you!