The Emergency and Post-Lubrication System of TCA Turbochargers

For the TCA turbocharger series a new emergency and post-lubrication system has been developed. This new system is supposed to maintain more than 10 seconds full load operation after an oil pump blackout. Moreover, the system has to efficiently supply oil for the run-out period and for cooling the bearings. In order to check this development target turbocharger TCA 77 was subjected to some tests. The tests were carried out under extreme conditions, i.e. maximum oil inlet temperature and minimum oil pressure. At maximum speed = 14900 rpm, t_oil = 60°C and p_oil = 1.3 bar the turbocharger continued its operation after stop of the oil pump without temperature increase in the bearings for 14 seconds before the pressure control device interrupted the fuel supply at 0.6 bar oil pressure. The pressurized part of the tank was sufficient for another 35 seconds during which the turbocharger speed dropped from 14900 rpm to a speed of about 7000 rpm. Both journal bearings and the axial bearings received oil for 2.5 minutes after pump stop. At this point the turbocharger still had a speed of 1500 rpm. After that the turbine bearing was cooled over a period of 1-1/2 hours by a geodetic driven oil flow. The maximum temperature at the turbine bearing of 180 °C (admissible approx. 220 °C) was achieved after 2 hours.