Box accessory in an airplane engine

Abstract

An airplane engine accessory box carrying an electrical machine such as an alternator, having a rotor that is guided in rotation in a bearing carried by a support part made of a material having a low coefficient of thermal expansion, itself carried by a stator cover that acts as a heat bridge between the body of the stator of the electrical machine and the casing of the accessory box.

Description

Technical field [0001] The invention relates to an accessory box used in an aircraft engine such as a turbojet engine or a turboprop engine. The accessory box has a metal shell and a generator at one end, especially a stator winding and a permanent magnet rotor for the engine Some of the equipment is powered by an alternator. Background technique [0002] The rotor of the generator is supported by an annular cover used to close the stator of the generator and used to fix it on the enclosure of the accessory box, usually guided by bearings such as rollers or ball bearings. [0003] The generator is characterized by a higher speed and lower load, which in turn produces dynamic phenomena that damage the bearings. [0004] In order to avoid or at least reduce this defect, a cover made of titanium with a lower coefficient of thermal expansion is used, thus limiting the difference in thermal expansion between the outer ring of the bearing and the part of the cover where the ring is mou...

AI Technical Summary

Problems solved by technology

[0007]However, due to the poor thermal conductivity of titanium (its thermal conductivity is about 1 / 20 that of aluminum), the stator cover of the generator hinders heat dissipation

This creates a build-up of heat and significantly increases the temperature of the generator, thereby coking the oil in the generator and overheating the stator with the risk of damaging its mechanical properties

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