Patent ID: 8291715

Claim:
A bi-modal turbine assembly for use in conjunction with a gas turbine engine, the bi-modal turbine assembly comprising: a housing assembly having a flow passage therethrough; a turbine wheel rotatably mounted in the housing assembly and positioned so as to be driven by pressurized air flowing through the flow passage; an output shaft rotatably mounted in the housing assembly; a first gear train disposed in the housing assembly and having a first gear ratio selected such that the bi-modal turbine assembly produces peak output power between a first engine speed generally indicative of engine lightoff and a second engine speed generally indicative of flight idle; a second gear train disposed in the housing assembly and having a second gear ratio less than the first gear ratio and selected such that the bi-modal turbine assembly produces peak output power between the second engine speed generally indicative of flight idle and a third engine speed generally indicative of engine cruise; and a switching device disposed in the housing assembly and configured to mechanically couple: (i) the first gear train between the turbine wheel and the output shaft in a first operational mode, and (ii) the second gear train between the turbine wheel and the output shaft in a second operational mode.