# US 12,009,703 B2 · Rotor-cooling structure of a drive motor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,009,703 B2 - Document ID: US12009703B2 - Status: Granted - Kind: B2 - Application number: 17/516,388 - Filed: 2021-11-01 - Published: 2022-09-15 - Granted: 2024-06-11 - Earliest claimed: 2021-03-10 - Assignees: Hyundai Motor Company; Kia Corporation - Applicants: Hyundai Motor Company; Kia Corporation - Inventors: Hong Seok Yang; Tae Ho Kim; Jae Won Ha; Jae Young Choi - Web page: https://patentgrep.com/patent/US12009703B2 ## CPC - H02K 1/32: with channels or ducts for flow of cooling medium - H02K 5/203: {specially adapted for liquids, e.g. cooling jackets} - H02K 9/19: for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil - Y02T 10/64: Electric machine technologies in electromobility - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A rotor-cooling structure is for a drive motor including an inner shaft, a rotor shaft surrounding the inner shaft, a rotor connected to the rotor shaft, and a stator disposed to be spaced apart from the rotor. The rotor-cooling structure includes: a first flow passage formed in the inner shaft; a second flow passage formed in the rotor shaft to receive oil through the first flow passage; a third flow passage formed in a plate disposed at an end of a rotor core, constituting the rotor, to be connected to the second flow passage; and a fourth flow passage formed to be connected to the third flow passage and to penetrate the rotor core in the direction in which core plates constituting the rotor core are stacked. ## Claims ### Claim 1 A rotor-cooling structure of a drive motor including an inner shaft, a rotor shaft surrounding the inner shaft, a rotor connected to the rotor shaft, and a stator disposed to be spaced apart from the rotor, the rotor-cooling structure comprising: a first flow passage formed in the inner shaft; a second flow passage formed in the rotor shaft to receive oil through the first flow passage; a third flow passage formed in a plate disposed at an end of a rotor core, constituting the rotor, to be connected to the second flow passage; and a fourth flow passage formed to be connected to the third flow passage and to penetrate the rotor core in a direction in which core plates constituting the rotor core are stacked, wherein the third flow passage extends in a direction from the rotor shaft toward an outer circumference of the rotor core, wherein an uppermost portion of the rotor core that is adjacent to the plate contacts the oil flowing through the third flow passage, wherein the third flow passage is inclined in a direction opposite a rotating direction of the rotor at a predetermined angle with respect to a direction from a center of the inner shaft toward the outer surface of the rotor core, wherein the third flow passage and the fourth flow passage are provided in a plurality thereof, and the number of fourth flow passages is the same as the number of third flow passages, and wherein the fourth flow passages are spaced apart from permanent magnets provided in the rotor. ### Claim 2 (depends on 1) The rotor-cooling structure of claim 1, wherein the first flow passage is formed in an axial direction of the inner shaft. ### Claim 3 (depends on 1) The rotor-cooling structure of claim 1, wherein the second flow passage is formed to penetrate the rotor shaft in a direction moving away from the inner shaft. ### Claim 4 (depends on 3) The rotor-cooling structure of claim 3, wherein the inner shaft has a discharge hole formed therein to discharge the oil, and wherein the discharge hole communicates with the second flow passage. ### Claim 5 (depends on 1) The rotor-cooling structure of claim 1, wherein the plate comprises a first plate, located at one end of the rotor core, and a second plate, located at an opposite end of the rotor core, and wherein the third flow passage is formed in the first plate. ### Claim 6 (depends on 5) The rotor cooling structure of claim 5, wherein the oil introduced into the third flow passage flows through the fourth flow passage and is discharged through a plate hole formed in the second plate. ### Claim 7 (depends on 6) The rotor-cooling structure of claim 6, wherein a point at which the third flow passage and the fourth flow passage meet corresponds to one end of the fourth flow passage, and a point at which the plate hole and the fourth flow passage meet corresponds to an opposite end of the fourth flow passage. ### Claim 8 (depends on 7) The rotor cooling structure of claim 7, wherein a first point at which the third flow passage and the fourth flow passage meet and a second point at which the fourth flow passage and the plate hole meet are offset based on the direction in which the rotor shaft extends. ### Claim 9 (depends on 1) The rotor-cooling structure of claim 1, wherein the fourth flow passage is formed in a space between the rotor shaft and a pair of the permanent magnets constituting one of poles of the rotor. ### Claim 10 (depends on 1) The rotor-cooling structure of claim 1, wherein the fourth flow passage is formed to be curved toward an outer circumference of the rotor core. ### Claim 11 (depends on 1) The rotor-cooling structure of claim 1, wherein at least one of the plurality of third flow passages and at least one of the plurality of fourth flow passages are formed in each of regions corresponding to poles of the rotor. ### Claim 12 (depends on 1) The rotor-cooling structure of claim 1, further comprising: a fifth flow passage formed in the rotor shaft to discharge the oil passing through the first flow passage, wherein the oil discharged from the fifth flow passage is moved toward the stator by rotation of the rotor. ### Claim 13 (depends on 1) The rotor-cooling structure of claim 1, further comprising: an oil pump provided in a housing accommodating the rotor and the stator to supply the oil to the inner shaft, wherein the oil supplied by the oil pump cools the rotor while flowing through the first flow passage, the second flow passage, the third flow passage, and the fourth flow passage.