Hybrid aircraft power plant and method of operation
The hybrid aircraft power plant can have a load, a thermal engine coupled to drive the load via a clutch, and coupled to drive a first lubricant pump, an electric motor coupled to drive the load and a second lubricant pump. In a first mode, the clutch is in an engaged configuration, and the thermal engine drives the load via the clutch and drives the first lubricant pump. In a second mode, in which the clutch is in the disengaged configuration and in which the thermal engine may be inoperative, the electric motor is operated to drive the load and the second lubricant pump.
1 . A method of operating a hybrid aircraft power plant having a thermal engine coupled to a propeller via a clutch, a first lubricant pump coupled to the thermal engine, an electric motor coupled to the propeller via a geartrain, a propeller control unit (PCU) coupled to the geartrain, and a second lubricant pump coupled to the electric motor, the method comprising:
operating the hybrid aircraft power plant in a first mode of operation in which the clutch is in an engaged configuration, including operating the thermal engine to drive the propeller via the clutch and to drive the first lubricant pump and the second lubricant pump to circulate lubricant to the geartrain and to the PCU via a lubricant circuit, the first lubricant pump and the second lubricant pump both contributing to a total lubricant pressure in the lubricant circuit, the total lubricant pressure being too high for the PCU;
regulating the total lubricant pressure using a pressure regulation valve upstream of the PCU, including recirculating a portion of the lubricant upstream of the PCU, thereby limiting a lubricant pressure at the PCU and protecting the PCU from excessive pressure;
changing a configuration of the clutch between the engaged configuration and a disengaged configuration, the thermal engine being decoupled from the propeller when the clutch is in the disengaged configuration; and
operating the hybrid aircraft power plant in a second mode of operation in which the clutch is in the disengaged configuration, including operating the electric motor to drive the propeller and to drive the second lubricant pump to circulate the lubricant to the geartrain and to the PCU.
2 . The method of claim 1 , wherein said changing the configuration of the clutch includes interrupting said recirculating.
3 . The method of claim 1 , wherein the first mode further includes freewheeling the electric motor.
4 . The method of claim 1 , wherein the second mode further includes maintaining the thermal engine in an inoperative state.
5 . The method of claim 1 , wherein the thermal engine of the hybrid aircraft power plant is coupled to the clutch via reduction gearing, wherein the first mode further includes the first lubricant pump circulating lubricant to the thermal engine and to the reduction gearing, wherein the second mode further includes neither the first lubricant pump nor the second lubricant pump circulating the lubricant, neither to the thermal engine nor to the reduction gearing.
6 . The method of claim 1 , wherein the first mode further includes the first lubricant pump circulating a lubricant to the clutch, wherein the second mode further includes the second lubricant pump circulating the lubricant to the clutch.
7 . The method of claim 1 , therein the hybrid aircraft power plant further has at least one of a heat exchanger, an inverter and a controller associated to the electric motor, wherein the first mode further includes the first lubricant pump circulating lubricant to the at least one of the heat exchanger, the inverter and the controller, wherein the second mode further includes the second lubricant pump circulating lubricant to the at least one of the heat exchanger, the inverter and the controller.