Vibration inspection of rotational imbalance of turbo-charger impeller for automobile

This paper describes a method for the detection of unbalanced mass in turbo-charger impellers of automobiles. This method uses vibration signals, through which the size and location of the unbalanced mass can be evaluated successfully and used to reduce any excess vibration. The continuous unbalanced distribution of the turbo-charger was assumed to be concentrated at two planes along the rotational axis in order to derive a transfer matrix for the relationship between the imbalance and its corresponding vibrations. Coefficients of the transfer matrix were determined experimentally in modal coordinates to calculate the imbalance of the turbo-charger. This was achieved by measuring the vibrations of two trial masses that were independently applied to the turbo-charger. Experimental equipment to operate turbo-charger samples and measure the imbalance vibration was designed and developed for implementation and verification of the proposed method. Unbalanced turbo-charger impellers from manufacturers were tested with this equipment to determine the magnitude and location of residual imbalance of each sample. It was found that the imbalance of turbo-charger samples was detected accurately and that the vibration of the turbo-chargers could be reduced significantly by removing the residual imbalance