Abstract
The turbocharger is an essential component to realize the engine down-sizing. The moment of inertia of turbocharger rotor is an important parameter with respect to acceleration performance of the vehicle. It can be calculated from the CAD software based the geometry data and the material properties. But the accurate value of the inertia of turbocharger rotor must be measured through the experimental method. In this study, the measurement of moment of inertia of turbocharger rotor for 2.0 L spark-ignition engine was carried out. First, an experimental equipment using a trifilar method was designed and fabricated. Some optical devices, that is, photo sensor, counter, convex lens, etc, were used to increase the accuracy of the measurement. Second, error sensitivity for the equipment was analyzed. The error of period time and the radius can give big affects to the accuracy of the moment of inertia. When the amount of error of these two were each 1.0 %, maximum error of the moment of inertia was under 3.0 %. Third, the calibration for the equipment was performed using a calibration rotor which has similar shape to turbine rotor but simple. Calculated value from CAD software and measured one for the calibration rotor were compared. The total error of the equipment and the measurement is about 1.3 %. This result shows that the equipment can give the good result with resonable accuracy. Finally the moment of inertia of the turbine rotor and compressor wheel were measured. The coefficient of variations, the ratio of standard deviation to mean value, were reasonably small at 0.57 % and 0.73 % respectively. Therefore this equipment is suitable for the measurement of the moment of inertia of the turbine rotor and compressor wheel.
