34 3. NVH TESTING AND ANALYSIS OF HYBRID POWERTRAINS
2215 Hz in Fig. 3.9 is the gear shaper cutter, which is adopted to produce the planetary gears.
e noise contributions measured agree with the numerical results as well. Table 5.1 shows the
5th and 6th natural frequencies of the powertrain during the pure electric mode are 1584 Hz
and 2890 Hz, respectively. Figure 3.12 shows that some noises are focus around 1656 Hz and
2886 Hz. erefore, the conclusion is the noise contributions obtained agree with numerical
ones and some mode shapes are excited in the pure driving mode.
3.3.2 TEST RESULTS OF WORKING CONDITION 2
Working condition 2 is the pure electric driving mode, where brake B1 is locked and the load
motor speed is 350 rpm. In addition, only motor E1 works and its torque is 30 Nm 0 Nm.
Figure 3.14 indicates the results of the microphone 1 in front of the power combiner. Figure 3.15
depicts the results of the microphone 2 located at the right part of the power combiner. Fig-
ure 3.16 depicts the noise of the microphone 3 located at the bottom of the power combiner.
Figure 3.17 shows the results of the acceleration sensor 1, and Fig. 3.18 shows the results of the
acceleration sensor 2.
Figures 3.14–3.16 show that the noise frequency is mainly concentrated around 1742 Hz,
3144 Hz, 3488 Hz, and 978 Hz. In addition, it also can be seen from Figs. 3.11–3.13 that noise
is also presented at 1572 and 2734 Hz.
Figures 3.17 and 3.18 show that the hybrid synthesizing box has the largest vibration
amplitude near 699 Hz, and also has large vibration amplitude near 1742 Hz, 3144 Hz, 3500 Hz,
and 2180 Hz.
In this condition, the speed of the load motor is 250 rpm, and the meshing frequency of
the gears in the CPGS can be expressed as [36]:
f
1
D
350
60
z
diff
z
m1
z
m2
z
r2
z
r1
D 1742 Hz: (3.4)
e meshing frequency of the outer ring and reducer is:
f
2
D
350
60
z
diff
z
m1
z
m2
D 978 Hz: (3.5)
erefore, under this mode, the gear meshing cause the main noise in the CPGS and the
gear meshing between outer ring and reducer is a major noise source. In addition, the contri-
bution at 3144 Hz is the gear shaper cutter, which is utilized to produce planetary gears. e
noise of 3500 Hz is the double frequency of 1742 Hz, which also agrees with the numerical
results. Moreover, the 5th and 6th natural frequencies of the powertrain in pure electric mode
are 1584 Hz and 2890 Hz, respectively. Figure 3.14 indicates that some noises appear around
1656 Hz and 2886 Hz. us, the conclusion is that noise contributions obtained agree with the
numerical results and some mode shapes are excited in this pure mode.
3.3. ANALYSIS OF THE EXPERIMENTAL RESULTS 35
Time (s)
A/dB
65
60
55
50
45
40
35
30
25
20
15
10
5
0
88
86
84
82
80
78
76
74
72
70
68
66
64
62
60
90
0 250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3500 3750 40003250
978.00 1742.5 2734.19 3144.68 3488.00
Frequency (Hz)
Figure 3.14: Test results for time-frequency responses of noise at microphone 1 under working
condition 2.
36 3. NVH TESTING AND ANALYSIS OF HYBRID POWERTRAINS
Time (s)
A/dB
43
40
38
35
33
30
28
25
23
20
18
15
13
10
8
5
3
0
88
86
84
82
80
78
76
74
72
70
68
66
64
62
60
90
0 250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3500 3750 40003250
978.00 1742.5
Frequency (Hz)
Figure 3.15: Test results for time-frequency responses of noise at microphone 2 under working
condition 2.
3.3. ANALYSIS OF THE EXPERIMENTAL RESULTS 37
Time (s)
A/dB
43
40
38
35
33
30
28
25
23
20
18
15
13
10
8
5
3
0
88
86
84
82
80
78
76
74
72
70
68
66
64
62
60
90
0 250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3500 3750 40003250
978.00 1742.6
1572.95
Frequency (Hz)
Figure 3.16: Test results for time-frequency responses of noise at microphone 3 under working
condition 2.
38 3. NVH TESTING AND ANALYSIS OF HYBRID POWERTRAINS
g/(9.8 m/s
2
)
0.480
0.450
0.425
0.400
0.375
0.350
0.325
0.300
0.275
0.250
0.225
0.220
0.175
0.150
0.125
0.100
0.075
0.050
0.025
0.000
0 250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3500 3750 40963250
Frequency (Hz)
Figure 3.17: Noise test results of acceleration sensor 1 under working condition 2.
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