The thesis describes the development and testing of a device for measuring car turbocharger’s unbalance. The device is based on measuring the oscillation of the force acting on rotor’s bearings. The force is proportional to the radial acceleration of the eccentric center of gravity of the rotor. This occurs mostly due to the non-homogenous material the turbine is made of. The radial acceleration is measured by a piezoelectric accelerometer. The starting point for measuring the phase shift of the radial acceleration is determined by a white colored blade of the turbine wheel.
The goal of this thesis is to determine whether it is possible to create a measuring device with sufficient sensitivity of measurements, with affordable components. Machines for measuring dynamic unbalance on the market are very high priced. For a small workshop or home master the expense is economically unjustified. Used accelerometer is made of a piezoelectric beeper, which output voltage is measured with a digital oscilloscope. An optical sensor detects the white colored turbine blade. The sensor’s signal is then fed into the oscilloscope’s external trigger input.
The thesis is divided into three main parts. The first part presents physical and mathematical background, describing the relationship between oscillations and vibrations. The second part is dedicated to the implementation of the measuring device. The third part tests its operation by measuring the unbalance of the turbine wheel of a medium-sized turbocharger. Based on measurements we conclude about the accuracy of the results and possible upgrades and improvements of the measuring device.
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