Aircraft power system

Abstract

Aircraft power system is disclosed having a hydraulic reservoir, a bi-directional hydraulic pump for pumping hydraulic fluid to and from the reservoir, and an electric motor. The electric motor is connectable to a first driveable component of the aircraft such that the electric motor is arranged to drive the first driveable component of the aircraft. The hydraulic pump is connectable to the first driveable component of the aircraft such that the hydraulic pump is arranged to pump hydraulic fluid from the reservoir to drive the first driveable component of an aircraft. Thus, in a first driveable mode of operation, the first driveable component is driven by both the electric motor and the hydraulic pump.

1 . An aircraft power system, wherein the aircraft power system comprises:
 i) a bi-directional hydraulic pump for pumping hydraulic fluid to and from a hydraulic reservoir,   ii) an electric motor, and   iii) a transfer unit;   and further wherein   the electric motor is connectable to a first driveable component of an aircraft such that the electric motor is arranged to drive the first driveable component of the aircraft,   the bi-directional hydraulic pump is connectable to the first driveable component of the aircraft such that the bi-directional hydraulic pump is arranged to drive the first driveable component, and   the transfer unit is arranged to enable the electric motor and the drive shaft to be independently connected and disconnected, so that   in a driving mode of operation, the first driveable component is driven by both the electric motor and the bi-directional hydraulic pump.   
     
     
         2 . The aircraft power system of  claim 1 , wherein in the driving mode of operation, the electric motor and hydraulic pump are each capable of supplying power to the driveable component independently of the other. 
     
     
         3 . The aircraft power system of  claim 1 , wherein the electric motor and hydraulic pump are connected to each other in parallel such that, in the driving mode of operation, both are arranged to supply power to the driveable component independently of the other. 
     
     
         4 . The aircraft power system of  claim 1 , wherein transfer unit is configured to enable each of the hydraulic pump, the electric motor, and the first driveable component to be independently connected and disconnected from the other two of the hydraulic pump, the electric motor, and the first driveable component. 
     
     
         5 . The aircraft power system of  claim 1 , wherein the electric motor is connectable to the first driveable component via a drive shaft. 
     
     
         6 . The aircraft power system of  claim 5 , wherein the hydraulic pump is connectable to the first driveable component via the drive shaft. 
     
     
         7 . The aircraft power system of  claim 1 , wherein the hydraulic pump is also connectable to other driveable components of the aircraft. 
     
     
         8 . The aircraft power system of  claim 1 , wherein the electric motor is connectable to the hydraulic pump, via the transfer unit, such that the electric motor is arranged to drive the hydraulic pump to pump hydraulic fluid out of a reservoir. 
     
     
         9 . The aircraft power system of  claim 1 , wherein the electric motor is configured to store hydraulic power by driving the hydraulic pump, via the transfer unit, to pump hydraulic fluid to a hydraulic reservoir in a regenerating mode of operation. 
     
     
         10 . The aircraft power system of  claim 1 , wherein the first driveable component comprises one or more landing gear wheels. 
     
     
         11 . The aircraft power system of  claim 10 , wherein in the driveable mode of operation the electric motor and hydraulic pump are configured to drive the landing gear wheels to move the aircraft over the ground during taxiing of the aircraft. 
     
     
         12 . The aircraft power system of  claim 1 , further including a hydraulic reservoir to and from which the bi-directional hydraulic pump is arranged to pump hydraulic fluid. 
     
     
         13 . An aircraft landing gear drive system comprising the aircraft power system of  claim 1 , wherein the first driveable component comprises one or more landing gear wheels of the landing gear drive system, and wherein the electric motor and the hydraulic pump are both connected to the one or more landing gear wheels, such that the electric motor and the hydraulic pump are both able to drive the one or more landing gear wheels. 
     
     
         14 . An aircraft comprising the aircraft power system of  claim 1 . 
     
     
         15 . An aircraft comprising the aircraft landing gear drive system of  claim 13 , and further comprising a hydraulic reservoir to and from which the bi-directional hydraulic pump is arranged to pump hydraulic fluid. 
     
     
         16 . A method of driving a component of an aircraft comprising the steps of
 driving a first driveable component by both an electric motor and a hydraulic pump by combining their driving torque with a transfer unit, the hydraulic pump being arranged to pump hydraulic fluid to and from a hydraulic reservoir,   using the transfer unit to selectively connect the electric motor to and disconnect the electric motor from the driveable component, and   using the transfer unit to selectively connect the hydraulic pump to and disconnect the hydraulic pump from the driveable component.   
     
     
         17 . The method of  claim 16 , wherein the step(s) of using the transfer unit to selectively connect the electric motor to and disconnect the electric motor from the driveable component is/are performed independently of the step(s) of using the transfer unit to selectively connect the hydraulic pump to and disconnect the hydraulic pump from the driveable component. 
     
     
         18 . The method of  claim 16 , wherein the hydraulic pump provides hydraulic power to one or more other driveable components. 
     
     
         19 . The method of  claim 18 , wherein the electric motor drives the hydraulic pump to provide hydraulic power to said one or more other driveable components. 
     
     
         20 . A method of taxiing an aircraft along the ground by driving one or more landing gear wheels with an electric motor and a hydraulic pump by combining their driving torque with a transfer unit, the transfer unit being configured to enable
 the one or more landing gear wheels to be driven by the electric motor independently of the hydraulic pump;   the one or more landing gear wheels to be driven by the hydraulic pump independently of the electric motor; and   each of the hydraulic pump, the electric motor, and the first driveable component to be independently connected to and disconnected from at least one of the other two of the hydraulic pump, the electric motor, and the first driveable component.