Lucas Aerospace Power Equipment Corporation

Stephen F Brucker

Mohammad Shahamat

A bearing failure detector for an electrical generator includes a disc located within the bearing assembly near the location of the main bearings. The disc includes an electrically conductive ring encased in an insulation layer. The ring is exposed along inside diameter of the detector disc adjacent to the periphery of the shaft, but the dimensions of the inside diameter of the ring are slightly greater than the normal internal clearance of the main bearings, so that the shaft does not contact the ring unless the bearings are significantly worn. The detector ring is connected to a resistor with a large resistance which is monitored by a control circuit at all times. When the internal clearance of the main bearings has been enlarged by a predetermined amount, the ring contacts the shaft, changing the resistance monitored by the control circuit. This causes the control circuit to provide an indication that the bearings need replacement. The detector eliminates the need for preventive replacement of bearings at scheduled maintenance periods when the bearings may not actually need replacement because they are not sufficiently worn, saving service time and costs. Auxiliary bearings are provided to support the shaft when the shaft has contacted the detector, providing safe operation of the generator for a sufficient period of time after a bearing replacement indication has been provided until the bearing assembly is replaced.

Bearing failure detector for electric generator

An electric generator of the type that is oil-cooled and generally used in aircraft includes a fluid brake assembly. The fluid brake assembly includes a fluid brake rotor which is generally in the form of a fan or impeller which is connected to the drive shaft of the generator. Under normal conditions with the cooling oil withdrawn from the housing of the generator by the scavenge system, the fluid brake rotor freely turns with the shaft. When the oil scavenge system becomes incapacitated, the generator becomes 'flooded' and the fluid brake rotor acts as pump to try to pump the oil, creating a torque load on the drive shaft. This load is preferably greater than the shear strength of the shaft, causing the shaft to shear and disconnecting the generator from the aircraft engine. By shearing the drive shaft, the operation of the main engine is unaffected by the flooding of the generator, and serious failure of the aircraft engine is avoided.

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Aurora, OH, United States of America

Stephen F Brucker