Experimental Investigation of the Dynamic Loads in a Ball Bearing Turbocharger

The objectives of this investigation were to design and develop an experimental turbocharger test rig (TTR) to measure the shaft whirl of the rotating assembly and the axial and frictional loads experienced by the bearings. The TTR contains a ball bearing turbocharger (TC) that was instrumented and operated under various test conditions up to 55,000 rpm. In order to measure the thrust loads on the compressor and turbine sides, customized sensors were integrated into the TC housing. The anti-rotation (AR) pin that normally prevents the bearing cartridge from rotating was replaced with a custom-made load cell adapter system. This sensor was used to measure the frictional losses in the bearing cartridge without altering the operation of the TC. Proximity sensors (probes) were also installed in the compressor housing to monitor shaft whirl. Axial load results indicated that the compressor side bears most of the thrust load. As the backpressure or the speed of the TC was increased, the thrust load also increased. Frictional measurements from the AR pin sensor demonstrated low power losses in the ball bearing cartridge. For certain shaft speed ranges, the data from the sensors illustrated periodic trends in response to the subsynchronous whirl of the shaft.