Acoustic effects of the coolant mass flow of an electric machine of a hybrid drive train

In this application paper, the influence of the coolant mantle on the acoustic radiation behaviour of a hybrid drive train is investigated. This was done on an electric machine on an acoustic component test bench. The coolant mass flow around the electric machine stator was varied and then completely drained. The electrical machine remained mechanically unchanged; any variations were made to the feed pumps on the test bench side. Triaxial acceleration sensors are glued to the machine housing and reviewed as evaluation criteria. For the evaluation, the square mean value of all three spatial directions of the glued acceleration sensors was calculated. The evaluation shows that there is no significant acoustic difference between an active stator cooling jacket and a stationary stator cooling jacket. If the stator cooling jacket is pumped out empty so that air remains in it, there is a strong reduction in surface acceleration. The observations are confirmed by analytical literature values. The results presented serve as a basis for further work and developments.