Feature Extraction of Gearbox based on Order Analysis of Instantaneous Angular Speed

As key components in a mechanical transmission chain, gearboxes work in non-stationary conditions in many cases and the effect of conventional vibration analysis is limited by low signal-noise ratio. Considering the advantage of Instantaneous Angular Speed (IAS), this paper proposes a gearbox feature extraction method based on the order analysis of IAS signals. Firstly, IAS signals of the input and output shafts are sampled synchronously by photoelectric encoders. Then the instantaneous angular speed difference (IASD) between the input shaft and output shaft is calculated to eliminate the interference of the transmission channel. Finally, the order spectrum of the gearbox can be obtained by the Fourier transform of IASD signal. Thus, gearbox’s working status can be judged according to the characteristic distribution of rotational components in the order spectrum. The effectiveness of this method has been validated experimentally on a two-stage gearbox test rig.