Patent ID: 7250688
Filing Date: 2007-07-31
Classification: F02C,F05D,H02K

Abstract:
1. A starter/generator system for starting a gas turbine engine for aeronautical applications in a starting mode and generating alternating current (AC) power within a desired band of frequencies in a generating mode comprising: an alternating current dynamoelectric machine; a torque converter with an input shaft coupled to a drive shaft of the dynamoelectric machine; a first rotation-speed selective coupling with an input shaft coupled to an output shaft of the torque converter and an output shaft coupled to a drive shaft of the engine, wherein the first coupling transfers power from its input shaft to its output shaft so long as the input shaft rotates at least as fast as the output shaft for coupling the dynamoelectric machine through the torque converter to the engine during the starting mode; a mechanical differential with an input shaft coupled to the drive shaft of the engine, a trim shaft coupled to the output shaft of the torque converter, and an output shaft that has a rotational speed that is proportional to the sum of the rotational speeds of its input shaft and trim shaft; a second rotation-speed selective coupling with an input shaft coupled to an output shaft of the differential and an output shaft coupled to the drive shaft of the dynamoelectric machine, wherein the second coupling transfers power from its input shaft to its output shaft so long as the input shaft rotates at least as fast as the output shaft for coupling the engine through the differential during the generating mode; a hydraulic fluid source for selectively filling the torque converter with hydraulic fluid to provide rotational power from the dynamoelectric machine to the engine during the starting mode; and an electronic control unit for switching the dynamoelectric machine from the starting mode to the generating mode when the engine reaches a self-sustaining rotational speed, coupling the hydraulic source to the torque converter in the starting mode and regulating the flow of hydraulic fluid from the hydraulic source to the torque converter to adjust the rotational speed of the output shaft of the torque converter and the trim shaft of the mechanical differential to which it couples in the generating mode to keep the frequency of AC power generated by the dynamoelectric machine within the desired band of frequencies.