Noisy worm gear unit determining method for reduction gear of electric window lifter of automobile, involves determining whether amplitude lies under normal distribution of noise-reduced worm gear unit or distribution of noisy gear unit

摘要

The method involves executing a discrete Fourier transformation of a signal for obtaining a spectrum of the signal, where the signal provides information about a profile of a winding surface of a worm gear unit with unknown sound intensity. Amplitude of the spectrum of the signal is calculated in an area of determined main upper vibration components, and the amplitude is compared with normal distributions. A determination is made that whether the amplitude lies under the normal distribution of a noise-reduced worm gear unit or under the normal distribution of a noisy worm gear unit. An independent claim is also included for an apparatus for determining a noisy worm gear unit comprising a transmitter arranged radial to a worm gear unit.