# US 2025/0083807 A1 · Systems and methods for lifter motor cooling in evtol aircraft > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0083807 A1 - Document ID: US20250083807A1 - Status: Published application - Kind: A1 - Application number: 18/956,397 - Filed: 2024-11-22 - Published: 2025-03-13 - Earliest claimed: 2022-10-07 - Assignees: Archer Aviation Inc. - Applicants: Archer Aviation Inc. - Inventors: Karthik Kumar BODLA; Bharat TULSYAN; Christopher M. HEATH; Kerry MANNING; Alan D. TEPE - Web page: https://patentgrep.com/patent/US20250083807A1 ## CPC - B64C 29/0033: {the propellers being tiltable relative to the fuselage} - B64D 27/026: {comprising different types of power plants, e.g. combination of a piston engine and a gas-turbine (Hybrid electric aircraft B64D27/33)} - B64D 27/24: using steam or spring force (jet aircraft B64D27/16) - B64D 27/33: Hybrid electric aircraft - B64D 27/34: All-electric aircraft - B64D 31/18: for hybrid-electric power plants - B64D 33/08: of power plant cooling systems - Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft - B64C: AEROPLANES; HELICOPTERS - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract An apparatus for aircraft propulsion includes a propeller and a hybrid-cooled electric engine mounted to a support structure and configured to rotate the propeller. The electric engine is located in an enclosure, with a first heat transfer element thermally coupled to the electric engine via a fluid flow path, partially located outside the enclosure. A second heat transfer element, integral to or thermally coupled to the electric engine, provides air cooling. Both heat transfer elements are housed within the aircraft's support structure. At least one air inlet on the upper side of the support structure receives propeller downwash. A first cooling path directs a portion of the downwash from the air inlet to the first heat transfer element, and a first air outlet exhausts the downwash. ## Claims ### Claim 1 An apparatus for aircraft propulsion, comprising: a propeller; a hybrid-cooled electric engine mounted to a support structure and configured to rotate the propeller, the electric engine being located within an enclosure; a first heat transfer element that is thermally coupled to the electric engine via a fluid flow path, wherein at least part of the first heat transfer element is located external to the enclosure; a second heat transfer element that is integral to or thermally coupled to the electric engine for air cooling; the first heat transfer element and the second heat transfer element being located within the support structure; at least one air inlet located at an upper side of the support structure, wherein the at least one air inlet is configured to receive downwash from the propeller; a first cooling path configured to direct a first portion of the downwash from the at least one air inlet to the first heat transfer element; and a first air outlet configured to exhaust the first portion of the downwash from the first heat transfer element. ### Claim 2 (depends on 1) The apparatus for aircraft propulsion of claim 1, wherein the first heat transfer element comprises a heat exchanger. ### Claim 3 (depends on 1) The apparatus for aircraft propulsion of claim 1, wherein: the electric engine comprises a motor; and the enclosure comprises a motor enclosure enclosing the motor, wherein the fluid flow path is configured to circulate a fluid within the motor enclosure. ### Claim 4 (depends on 1) The apparatus for aircraft propulsion of claim 1, wherein the fluid flow path comprises one of an oil or a coolant. ### Claim 5 (depends on 2) The apparatus for aircraft propulsion of claim 2, wherein the second heat transfer element comprises air-cooling fins that are integral to or thermally coupled to the electric engine. ### Claim 6 (depends on 1) The apparatus for aircraft propulsion of claim 1, further comprising: a second cooling path configured to direct a second portion of the downwash from the at least one air inlet to the second heat transfer element. ### Claim 7 (depends on 1) The apparatus for aircraft propulsion of claim 1, further comprising: a second cooling path configured to direct a second portion of the downwash from the at least one air inlet to the second heat transfer element; and wherein the first air outlet is configured to exhaust the second portion of the downwash from the second heat transfer element. ### Claim 8 (depends on 6) The apparatus for aircraft propulsion of claim 6, further comprising: a second air outlet, wherein the second air outlet is configured to exhaust the second portion of the downwash from the second heat transfer element. ### Claim 9 (depends on 8) The apparatus for aircraft propulsion of claim 8, wherein the second air outlet is located at an upper side of the support structure. ### Claim 10 (depends on 9) The apparatus for aircraft propulsion of claim 9, wherein the second air outlet is annular to or adjacent to a hub of the electric engine. ### Claim 11 (depends on 9) The apparatus for aircraft propulsion of claim 9, wherein the second air outlet is located on a top face of the support structure. ### Claim 12 (depends on 6) The apparatus for aircraft propulsion of claim 6, wherein the second cooling path is configured to direct the second portion of the downwash from the at least one air inlet, to the second heat transfer element, and then to the first heat transfer element. ### Claim 13 (depends on 1) The apparatus for aircraft propulsion of claim 1, wherein the first cooling path is configured to direct the first portion of the downwash from the at least one air inlet to the first heat transfer element and then to the second heat transfer element. ### Claim 14 (depends on 3) The apparatus for aircraft propulsion of claim 3, wherein: the electric engine further comprises an inverter; and the enclosure comprises an inverter enclosure enclosing the inverter and a dividing plate between an electric engine enclosure enclosing the electric engine and the inverter enclosure, wherein the dividing plate is configured to thermally couple the inverter to the fluid flow path. ### Claim 15 (depends on 3) The apparatus for aircraft propulsion of claim 3, wherein: the electric engine comprises a gearbox; and the enclosure comprises a gearbox enclosure enclosing the gearbox, wherein the fluid flow path is configured to circulate fluid within the gearbox enclosure. ### Claim 16 An apparatus for aircraft propulsion, comprising: a propeller; an electric engine mounted to a support structure having a longitudinal axis through the center of the support structure, wherein the electric engine is configured to rotate a propeller, the electric engine being located within an enclosure; a first heat transfer element that is thermally coupled to the electric engine, wherein at least part of the first heat transfer element is located external to the enclosure; a first air inlet located at an upper side of the support structure, wherein the first air inlet is configured to receive downwash from the propeller during a lift phase, and wherein the first air inlet is radially offset from a hub of the electric engine and the first air inlet is laterally offset from the longitudinal axis, wherein an amount of the lateral offset positions the first air inlet in a region of high downwash pressure or airflow; a first cooling path configured to direct a first portion of the downwash from the first air inlet to the first heat transfer element; and a first air outlet configured to exhaust the first portion of the downwash from the first heat transfer element. ### Claim 17 (depends on 16) The apparatus for aircraft propulsion of claim 16, wherein the first heat transfer element comprises a heat exchanger. ### Claim 18 (depends on 17) The apparatus for aircraft propulsion of claim 17, further comprising: a fluid flow path, wherein the heat exchanger is thermally coupled to the electric engine by the fluid flow path. ### Claim 19 (depends on 18) The apparatus for aircraft propulsion of claim 18, wherein the fluid flow path comprises one of an oil or a coolant. ### Claim 20 (depends on 18) The apparatus for aircraft propulsion of claim 18, wherein: the electric engine further comprises an inverter; and the enclosure comprises an inverter enclosure enclosing the inverter and a dividing plate between an electric engine enclosure enclosing the electric engine and the inverter enclosure, wherein the dividing plate is configured to thermally couple the inverter to the fluid flow path. ### Claim 21 (depends on 18) The apparatus for aircraft propulsion of claim 18, wherein: the electric engine comprises a gearbox; and the enclosure comprises a gearbox enclosure enclosing the gearbox, wherein the fluid flow path is configured to circulate fluid within the gearbox enclosure. ### Claim 22 (depends on 16) The apparatus for aircraft propulsion of claim 16, further comprising: a second heat transfer element that is thermally coupled to the electric engine, wherein at least part of the second heat transfer element is located external to the enclosure; and a second cooling path configured to direct a second portion of the downwash from the first air inlet to the second heat transfer element. ### Claim 23 (depends on 22) The apparatus for aircraft propulsion of claim 22, further comprising: a second air outlet, wherein the second air outlet is configured to exhaust the second portion of the downwash from the second heat transfer element. ### Claim 24 (depends on 23) The apparatus for aircraft propulsion of claim 23, wherein the second air outlet is located at an upper side of the support structure. ### Claim 25 (depends on 24) The apparatus for aircraft propulsion of claim 24, wherein the second air outlet is annular to or adjacent to a hub of the electric engine. ### Claim 26 (depends on 22) The apparatus for aircraft propulsion of claim 22, wherein the second heat transfer element comprises air-cooling fins integral to or thermally coupled to a part of the electric engine. ### Claim 27 (depends on 16) The apparatus for aircraft propulsion of claim 16, wherein the amount of lateral offset is based on a swirl component of the downwash. ### Claim 28 (depends on 16) The apparatus for aircraft propulsion of claim 16, further comprising a second air inlet configured to receive a second portion of the downwash and cool the electric engine, wherein the second air inlet is laterally offset from the longitudinal axis in a direction opposite from the lateral offset of the first air inlet, wherein an amount of the lateral offset of the second air inlet positions the second air inlet in a second region of high downwash pressure or airflow. ### Claim 29 (depends on 28) The apparatus for aircraft propulsion of claim 28, wherein a second cooling path is configured to direct the second portion of the downwash from the second air inlet to the first heat transfer element. ### Claim 30 (depends on 28) The apparatus for aircraft propulsion of claim 28, wherein the second air inlet is offset from the first air inlet in a longitudinal direction.