The Researching Of No Tachometer Order Analysis Method

Rotating machinery has become a key equipment in industry. Most of which are running under the condition of variable load and variable speed. With increase of the speed requirements, the fluctuations of speed wave should not be overlooked. The process of speeding contains rich fault information which has unique value for fault diagnosis in rotating machinery. Order tracking analysis is one of the most important methods of rotating machinery to deal with vibration signal. The traditional order analysis method generally includes some specific hardware, such as tachometer and photoelectric encoder.Although accuracy of this method is higher, it is not convenient to be used as a result of limited installation occasion in practical application. Therefore, an effective research,without tachometer order analysis method,has become a hot topic. In order to solve this problem, this paper proposes the no tachometer order analysis method based on instantaneous frequency estimation.Main jobs of this paper are as following:The paper carries on the accurate analysis for common failure mechanism for rotating machinery, and introduces the corresponding feature of various fault vibration signal. The effective estimation signal of the instantaneous frequency is the precondition of speed information. For rotating machinery, the vibration signal under variable conditions is non-stationary and characteristic of multi-component. Firstly, this paper adopts the EMD decomposition method to turn multi-component signal into a series of single component,and extracts the sensitive component of the IMF based on the correlation coefficient method. Then the instantaneous frequency of sensitive IMF is extracted respectively by using Hilbert transform and Teager energy operator method. By comparative analysis, it is fact that Hilbert transform method can represent the instantaneous frequency of the signalclearly. In order to eliminate the EMD endpoint effect of instantaneous frequency analysis,the instantaneous frequency curve is processed into a piece-wise and smooth curve to reduce the volatility of the instantaneous frequency and improve accuracy of instantaneous frequency estimation. The simulation experiments verify the effectiveness of the piecewise fitting method.In order to verify the effectiveness of this method, hydraulic system of vibration rotor rotating machinery misalignment is established. Combining with fault mechanism and accurate analysis of test data, experimental results demonstrate the feasibility and effectiveness of the no tachometer order analysis method proposed in this paper.