2nd ICAI 2022

International Conference on Automotive Industry 2022

Mladá Boleslav, Czech Republic

overview of all excitation frequencies and resonance frequencies. Only in the case of such an overview, it is possible to optimize the transmission to reduce noise emissions. This overview enables us to control both – the durability calculation and the dynamic properties. Figure 8 shows examples of the actual modal shapes of the gearbox housing and the motor. Figure 8: Examples of the mode shapes

Source: own elaboration (2021) Before starting the calculation of the acoustic emission emitted from the gearbox housing, it is necessary to calculate the TE (Transmission Error) in the entire speed and load spectrum as a basis for the ODS (Operation Deflection Shape) calculation. Based on the complete ODS calculation, it is possible to start the calculation of the sound pressure level of the gearbox at a distance of 1m from the surface of the gearbox. An example of the acoustic field around the gearbox is shown in Figure 9. The figure clearly shows that the noise emission differs from one side of the gearbox to the other.

Figure 9: Acoustic field of gearbox (Romax, using embedded technology from Actran)

Source: own elaboration (2021) At each point where there is an arrow, it is possible to read the result of the sound pressure level as a function of speed (Fig. 10) and the sound pressure spectrogram (Fig. 11). Several resonances amplifications can be seen in figure 10 from the sound pressure for the harmonics of the gear mesh frequency from 0 to the maximum rpm. If these areas exceeded the summarized limit of sound pressure level, the gearbox would need to be re-optimized. In this case, limit has not been exceeded.

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