Hybrid power plant for aircraft

Abstract

An hybrid aircraft power plant, has: a gas turbine engine having a high-pressure spool including a high-pressure compressor, a high-pressure turbine, and a high-pressure shaft drivingly engaging the high-pressure turbine to the high-pressure compressor, a low-pressure spool including a low-pressure compressor, a low-pressure turbine, and a low-pressure shaft drivingly engaging the low-pressure turbine to the low-pressure compressor; an electric motor drivingly engaged to the low-pressure shaft; and a torque-transmitting device operatively connected to the HP-shaft and having an engaged configuration in which the torque-transmitting device drivingly engages the electric motor to the high-pressure shaft and a disengaged configuration in which the torque-transmitting device disconnects the electric motor from the high-pressure shaft.

1 . An hybrid aircraft power plant, comprising:
 a gas turbine engine having
 a high-pressure spool including a high-pressure compressor, a high-pressure turbine, and a high-pressure shaft drivingly engaging the high-pressure turbine to the high-pressure compressor, 
 a low-pressure spool including a low-pressure compressor, a low-pressure turbine, and a low-pressure shaft drivingly engaging the low-pressure turbine to the low-pressure compressor; 
   an electric motor drivingly engaged to the low-pressure shaft; and   a torque-transmitting device operatively connected to the HP-shaft and having an engaged configuration in which the torque-transmitting device drivingly engages the electric motor to the high-pressure shaft and a disengaged configuration in which the torque-transmitting device disconnects the electric motor from the high-pressure shaft.   
     
     
         2 . The hybrid aircraft power plant of  claim 1 , comprising a transmission including the torque-transmitting device, the transmission having an input drivingly engaged by the electric motor, a first output drivingly engageable to the low-pressure shaft, and a second output drivingly engageable to the high-pressure shaft, the transmission operable in a first configuration in which the electric motor is drivingly engaged to the high-pressure shaft through the transmission and in a second configuration in which the electric motor is disengaged from the high-pressure shaft. 
     
     
         3 . The hybrid aircraft power plant of  claim 2 , wherein the torque-transmitting device is a clutch, the engaged configuration corresponding to the first configuration of the transmission and the disengaged configuration corresponding to the second configuration of the transmission. 
     
     
         4 . The hybrid aircraft power plant of  claim 3 , wherein the clutch is a sprag clutch, the sprag clutch transmitting a torque from the electric motor to the high-pressure shaft when the electric motor rotates at a higher rotational speed than that of the high-pressure shaft. 
     
     
         5 . The hybrid aircraft power plant of  claim 3 , wherein the electric motor is drivingly engaged to the low-pressure shaft in both of the first configuration and the second configuration of the transmission. 
     
     
         6 . The hybrid aircraft power plant of  claim 2 , wherein the transmission is further operable in a third configuration in which the electric motor is drivingly engaged to the low-pressure shaft through the transmission and in a fourth configuration in which the low-pressure shaft is disengaged from the electric motor. 
     
     
         7 . The hybrid aircraft power plant of  claim 6 , wherein the transmission includes a second clutch between the electric motor and the low-pressure shaft, the second clutch having an engaged configuration corresponding to the third configuration of the transmission and a disengaged configuration corresponding to the fourth configuration of the transmission. 
     
     
         8 . The hybrid aircraft power plant of  claim 1 , wherein the torque-transmitting device is a continuously variable transmission (CVT) having a CVT input drivingly engaged by the electric motor and a CVT output drivingly engaging the high-pressure shaft, the CVT operable to control a torque transmitted from the electric motor to the high-pressure shaft. 
     
     
         9 . The hybrid aircraft power plant of  claim 8 , comprising a second CVT having a second CVT input drivingly engaged by the electric motor and a second CVT output drivingly engaging the low-pressure shaft, the second CVT operable to control a torque transmitted from the electric motor to the low-pressure shaft. 
     
     
         10 . The hybrid aircraft power plant of  claim 1 , wherein the torque-transmitting device is a gear assembly having a master gear drivingly engaged to the electric motor, a first slave gear drivingly engaged to the high-pressure shaft, and a second slave gear drivingly engaged to the low-pressure shaft, the master gear is movable in a first position in which the master gear is meshed with the first slave gear and disengaged from the second slave gear, the master gear is movable in a second position in which the master gear is meshed with the second slave gear and disengaged from the first slave gear, the master gear is movable in a neutral position in which the master gear and the electric motor are disengaged from both of the first slave gear and the second slave gear and disengaged from both of low-pressure shaft and the high-pressure shaft. 
     
     
         11 . The hybrid aircraft power plant of  claim 1 , wherein the electric motor is drivingly engaged to the low-pressure shaft, the torque-transmitting device being a sprag clutch operatively connected to both of the high-pressure shaft and the low-pressure shaft, the sprag clutch operable to transmit a torque from the low-pressure shaft to the high-pressure shaft when a rotational speed of the low-pressure shaft is greater than that of the high-pressure shaft. 
     
     
         12 . A method of starting a hybrid aircraft power plant including a gas turbine engine and an electric motor drivingly engaged to an electric motor, comprising:
 drivingly engaging the electric motor to a high-pressure spool of the gas turbine engine;   increasing a rotational speed of the high-pressure spool to a target rotational speed;   igniting a mixture of air and fuel into a combustor of the gas turbine engine when the rotational speed of the high-pressure spool is at the target rotational speed; and   transmitting a torque between a low-pressure spool of the gas turbine engine and the electric motor.   
     
     
         13 . The method of  claim 12 , comprising disengaging the electric motor from the high-pressure spool after the igniting of the mixture of the air and the fuel in to the combustor. 
     
     
         14 . The method of  claim 12 , wherein the drivingly engaging of the electric motor to the high-pressure spool includes switching a clutch from a disengaged configuration to an engaged configuration or includes operating a continuously variable transmission in a torque transmission mode. 
     
     
         15 . The method of  claim 12 , wherein the drivingly engaging of the electric motor to the high-pressure spool includes driving the low-pressure spool with the electric motor and transmitting a torque from the low-pressure shaft to the high-pressure shaft via a sprag clutch. 
     
     
         16 . The method of  claim 12 , wherein the drivingly engaging of the electric motor to the high-pressure spool includes meshing a master gear drivingly engaged to the electric motor with a first slave gear drivingly engaged to the high-pressure spool, and wherein the transmitting of the torque between the electric motor and the low-pressure spool includes disengaging the master gear from the first slave gear and meshing the master gear to a second slave gear drivingly engaged to the low-pressure spool. 
     
     
         17 . The method of  claim 12 , wherein the transmitting of the torque between the electric motor and the low-pressure spool of the gas turbine engine includes switching a clutch from a disengaged configuration to an engaged configuration or includes operating a continuously variable transmission in a torque transmission mode. 
     
     
         18 . An hybrid aircraft power plant, comprising:
 a gas turbine engine having
 a high-pressure spool including a high-pressure compressor, a high-pressure turbine, and a high-pressure shaft drivingly engaging the high-pressure turbine to the high-pressure compressor, 
 a low-pressure spool including a low-pressure compressor, a low-pressure turbine, and a low-pressure shaft drivingly engaging the low-pressure turbine to the low-pressure compressor; 
   an electric motor drivingly engaged to an electric motor, the electric motor drivingly engaged to the low-pressure shaft; and   means for selectively drivingly engaging the electric motor to the high-pressure shaft.   
     
     
         19 . The hybrid aircraft power plant of  claim 18 , wherein the means are able to engage the electric motor to both of the high-pressure shaft and to the low-pressure shaft simultaneously. 
     
     
         20 . The hybrid aircraft power plant of  claim 18 , wherein the means are able to drivingly engage the electric motor to the low-pressure shaft while disengaging the electric motor from the high-pressure shaft.