US 11,973,385 B1
Electrical machines for aircraft power and propulsion systems
Ellis F H Chong, Derby (GB); Andreas Reeh, Nuremberg (DE); Johannes Gabriel Bauer, Neuried (DE); and Anton Rudenko, Ottobrunn (DE)
Assigned to Rolls-Royce Deutschland Ltd & Co KG, Blankenfelde-Mahlow (DE)
Filed by Rolls-Royce Deutschland Ltd & Co KG, Blankenfelde-Mahlow (DE)
Filed on May 24, 2023, as Appl. No. 18/201,607.
Claims priority of application No. 2300385 (GB), filed on Jan. 11, 2023.
Int. Cl. H02K 1/14 (2006.01); B64C 29/00 (2006.01); B64D 27/24 (2006.01); B64D 33/08 (2006.01); H02K 3/24 (2006.01); H02K 21/24 (2006.01)
CPC H02K 21/24 (2013.01) [B64D 27/24 (2013.01); B64D 33/08 (2013.01); H02K 1/145 (2013.01); H02K 3/24 (2013.01); B64C 29/0033 (2013.01); H02K 2201/12 (2013.01); H02K 2213/03 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A vertical take-off and landing (VTOL) aircraft comprising:
at least one electrical propulsion unit (EPU), wherein an EPU of the at least one EPU comprises:
a propeller or a fan; and
an electric motor including:
a stator having insulated coils for carrying current; and
a rotor arranged to interact with the stator, such that a torque for driving rotation of the propeller or the fan is produced,
wherein the EPU is arranged so that, in use, the insulated coils of the stator are supplied with a flow of coolant to remove heat from the insulated coils of the stator, the coolant having a specific heat capacity of Cp at international standard atmosphere (ISA) sea-level conditions,
wherein the electric motor is configured to produce a maximum continuous rated torque of τmax,cont,
wherein the electric motor has an active parts mass, mact, equal to a cumulated mass of components of the electric motor that contributes to the production of the torque,
wherein the electric motor has an active parts diameter, Dact, that is a diameter that corresponds to a radially outermost component of the electric motor configured to contribute to the production of the torque,
wherein an angular frequency of rotation of the rotor of the electric motor is ωmech,cont during the production of the maximum continuous rated torque by the electric motor,
wherein the insulated coils of the stator have a maximum rated insulation temperature of θins,max,
wherein a mass flow rate of the coolant required to maintain a temperature of an insulation of the insulated coils at or below the maximum rated insulation temperature during the production of the maximum continuous rated torque by the electric motor at the ISA sea-level conditions is mmax,cont,
wherein a dimensionless figure of merit, F, of the electric motor has a value greater than or equal to 1.9, the dimensionless figure of merit F being defined as:

OG Complex Work Unit Math
wherein:
pair,0 is a nominal ambient air pressure equal to 100 kPa;
θair,0 is a nominal ambient air temperature equal to 318 Kelvin; and
Dref is a nominal active parts diameter equal to 0.5 meters, and
wherein the electric motor is a radial flux electric motor or a transverse flux electric motor, and the rotor is a permanent magnet rotor.