Research of vibroacoustic signals in diagnostics of technical condition of engines of beet harvesters combines

Abstract

The authors of the experimental studies have proved from the possibility of vibration signals to detect the faults and changes in the parameters of the technical condition of engines of beet harvesters combines at the primary stages of their occurrence. Ensuring the predicted reliability of the conclusions, regarding the technical condition of the mechanisms and system of the engine, it can be achieved using the statistical evaluation of the correspondence of the temporal frequency fragments of the vibroacoustic signals and their correspondence to the rotational speed of the crankshaft. The authors investigated the difference between physical models and methods of their mathematical description in different parts of the frequency range and proved the feasibility of dividing it into three frequency subbands: low (0–200 Hz), medium (200–1000 Hz) and high (1 to 10–20 kHz). The authors found out that the series of harmonic signals of engines are characterized by the amplitudes, frequencies and initial phases, whose algebraic sum of ordinates at any given time is equal to the ordinate of the non-sinusoidal signal. Therefore, the Fourier series should be written as the sum of an infinite number of harmonic components of different frequencies. To distinguish the spectrum of the vibroacoustic signal in the diagnosis of the technical condition of engines of beet harvesters combines, it is necessary to use a Fast Fourier Transform. The processing of vibroacoustic signals in the diagnosis of the technical condition parameters of engines of beet harvesters combines is carried out using digital filters, which are implemented by the author’s algorithm.