Vibro-acoustic condition monitoring of Internal Combustion Engines: A critical review of existing techniques

The article describes a concept of a non-invasive method for diagnosing the size of valve clearance in internal combustion engines, based on the analysis of engine surface vibration signals using artificial neural networks. The applicability of the method was tested on a single-cylinder compression-ignition engine with a low power rating, which had an OHV timing gear, acting indirectly on the valves, and manual adjustment of valve clearance. The method uses as diagnostic signals the readings of vibration sensors, which record the acceleration of engine head movement as a function of the angle of rotation of the crankshaft, with pre-set valve clearance values measured in a cold condition. From among the signals recorded, components corresponding to the impact of rocker arms against valve stems were identified and low-pass filtered in order to eliminate measurement interference. A classifier of selected features of the signals processed was constructed using artificial neural networks. This classifier recognizes signals generated by engines with correct valve clearance as well as those with too much and too little valve clearance.

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Application of vibration signal in the diagnosis of IC engine valve clearance

The article addresses results of the research on the structure and propagation of vibration of vehicle for different parameters of suspension damping system. Long term exposure to whole-body vibration in transport may cause health risk and many diseases. Suspension is the most important system of vehicle for vibration control of level of wave emission to car-body and passengers. Thus the research on structure and propagation of vibration were conducted for different damping parameters of shock absorbers. For the sake of the analysis of exposure to whole-body vibration signals of general vibration were recorded at locations where vibration penetrated the human organism by the feet inside the vehicle. The vibrations have to be analyzed in the domains of amplitudes, time, frequency and time-frequency. Chosen estimators were defined and compared for the sake of the analysis of vibration propagation in terms of energy and dynamics. To evaluate the exposure to vibration it is important to analyse the dynamics of phenomena and main frequency components of vibration. For the spine response in vertical direction calculation of the model presented in ISO 2631 was used. The calculations of acceleration dose and equivalent static compressive stress for the assessment of health effects were done. Due to the large capacity of information in vibration signal the scope of presented research can be used for active diagnostics experiments on determining of estimators of technical condition of suspension elements.

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Research on structure, propagation and exposure to general vibration in passenger car for different damping parameters

A change in the technical condition of mechanical components of internal combustion engines may not be detected by on-board diagnostic systems installed in vehicles. In similar cases, measurements and analyses of vibroacoustic signals being recorded prove useful. Since there are certain limitations to vibration measurements, including those related to the vibration transmission and the engine’s high temperature at measurement points, the authors of this paper have proposed that measurements and analyses of acoustic signals should be applied for the sake of assessment of the internal combustion engine technical condition. However, such an assessment requires new acoustic signal processing methods to be developed, and so this subject has been elaborated in the paper. The article provides a discussion on the option of applying a wavelet packet decomposition while filtering the internal combustion engine’s acoustic signal in order to diagnose an excessive valve clearance. The authors prepared an algorithm enabling selection of the chosen details and approximation of the wavelet analysis to low-frequency components, which constitute the noise, as well as high-frequency components comprising information on the possible enlarged engine valve clearance. Next, based on the selected high-frequency acoustic signal components, a method for automatic detection of enlarged clearance valves was developed, assuming that energy participations of the acoustic signal being emitted were to be determined while opening and closing individual valves. Under the study discussed, identification tests were conducted using two 4-cylinder internal combustion engines featuring valves of different clearances to consequently confirm the efficiency of the algorithm developed for the acoustic signal filtration and automatic detection of enlarged clearance valves.

Condition monitoring of engine timing system by using wavelet packet decomposition of a acoustic signal

Numerical Analysis of Selected Materials for Flexsplines

Investigation of Gearbox Vibroactivity with the Use of Vibration and Acoustic Pressure Start-Up Characteristics

Summary. The paper attempts to assess the utility of sound pressure level registered in the near field of about 0,01 m away from the vibrating surface in the studies of the housing vibroacoustic activity. Based on the studies performed for the four pairs of wheels, with different loads and different speeds of gearbox, have been indicated the usefulness of the noise recorded in near field in vibroacoustic analysis.

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Comparison of the sound pressure measurement and the speed measurement of the gearbox vibrating surface

Vibration analysis is a very important tool in condition monitoring of operating machines. Many signal processing methods have been developed to extract information about incipient faults from externally measured vibration signals. The article presents the laboratory examinations of some faults in spur and helical gears. In case of spur gears two types of progressing local faults of cracked and chipped gear tooth were simulated and the smoothed pseudo Wigner-Ville distribution was used to demonstrate fault advancement via residual vibration signal analysis. Observing changes in the features of the WV distribution in the contour plots and changes of Kurtosis value monitored the progression of a fault. In case of helical gears some signal changes of transverse vibration velocity of shafts during the process of pitting growth in the tooth working surface have been investigated. Some new indices of pitting wear have been suggested and compared with other non-dimensional discriminants.Copyright © 2003 by ASME

Andrzej Wilk

Papers

Condition monitoring of engine timing system by using wavelet packet decomposition of a acoustic signal

Investigation of Gearbox Vibroactivity with the Use of Vibration and Acoustic Pressure Start-Up Characteristics

Comparison of the sound pressure measurement and the speed measurement of the gearbox vibrating surface

Vibration Processing Techniques for Fault Detection in Gearboxes

Analiza stanu bezpieczeństwa ruchu drogowego dla obszaru miasta