# US 2014/0197703 A1 · Electric motor rotor thermal interface for hub/shaft > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0197703 A1 - Document ID: US20140197703A1 - Status: Published application - Kind: A1 - Application number: 13/744,229 - Filed: 2013-01-17 - Published: 2014-07-17 - Earliest claimed: 2013-01-17 - Assignees: Remy Technologies, L.L.C. - Applicants: Remy Technologies, LLC - Inventors: Bradley D. Chamberlin - Web page: https://patentgrep.com/patent/US20140197703A1 ## CPC - H02K 9/223: {Heat bridges} - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) ## Abstract A cooling system of an electric machine includes a hub, a rotor core, and a thermal interfacial material interposed between respective complementary mating surfaces of the hub and the rotor core for substantially eliminating air gaps therebetween. A method of cooling an electric machine having a rotor core and a hub includes placing a thermal interfacial material onto a heat transfer interface between the rotor core and the hub, whereby the thermal interfacial material reduces contact resistance at the heat transfer interface. A method includes providing a rotor core having a radially inner surface, coating at least one of a radially outer surface of a hub and the radially inner surface of the rotor core with a thermal interfacial material, and inserting the hub into the rotor core, whereby the thermal interfacial material is interposed between the inner surface of the rotor core and the outer surface of the hub. ## Claims ### Claim 1 A cooling system of an electric machine, comprising: a hub member; a rotor core; and a thermal interfacial material interposed between respective complementary mating surfaces of the hub member and the rotor core for substantially eliminating air gaps therebetween. ### Claim 2 (depends on 1) The cooling system of claim 1, wherein the hub member includes a substantially cylindrical surface with an annular rim at an axial end thereof. ### Claim 3 (depends on 1) The cooling system of claim 1, wherein the hub member includes a hub and a shaft with thermal interfacial material placed therebetween. ### Claim 4 (depends on 1) The cooling system of claim 1, further comprising an annular heat sink secured to an axial end of the hub member, wherein the thermal interfacial material is interposed between the heat sink and the hub member. ### Claim 5 (depends on 1) The cooling system of claim 1, further comprising an annular perimeter seal around at least one axial end of the thermal interfacial material for enclosing the material between the complementary mating surfaces. ### Claim 6 (depends on 5) The cooling system of claim 5, wherein the seal(s) include epoxy. ### Claim 7 (depends on 5) The cooling system of claim 5, wherein the enclosed thermal interfacial material remains in a liquid state. ### Claim 8 (depends on 1) The cooling system of claim 1, wherein the complementary mating surfaces have an interference fit. ### Claim 9 (depends on 1) The cooling system of claim 1, wherein the thermal interfacial material is substantially uncurable thermal grease. ### Claim 10 (depends on 1) The cooling system of claim 1, wherein the thermal interfacial material has a nominal thickness between 0.002 mm and 0.5 mm. ### Claim 11 (depends on 1) The cooling system of claim 1, wherein the hub member comprises a unitary shaft. ### Claim 12 A method of cooling an electric machine having a rotor core and a hub member, comprising placing a thermal interfacial material onto a heat transfer interface between the rotor core and the hub member, whereby the thermal interfacial material reduces contact resistance at the heat transfer interface. ### Claim 13 (depends on 12) The method of claim 12, further comprising: heating and thereby expanding the rotor core; cooling and thereby shrinking the hub member; installing the cooled hub member within the heated rotor core; and cooling the rotor core so that the hub member is interference fit therein. ### Claim 14 A method of cooling a stator of an electric machine, comprising: providing a rotor core having a radially inner surface; coating at least one of a radially outer surface of a hub member and the radially inner surface of the rotor core with a thermal interfacial material; and inserting the hub member into the rotor core; whereby the thermal interfacial material is interposed between the inner surface of the rotor core and the outer surface of the hub member. ### Claim 15 (depends on 14) The method of claim 14, further comprising sealing the rotor core to the hub member, thereby enclosing axial ends of the thermal interfacial material. ### Claim 16 (depends on 15) The method of claim 15, wherein the sealing comprises curing the thermal interfacial material. ### Claim 17 (depends on 15) The method of claim 15, wherein the sealing comprises applying a bead of epoxy. ### Claim 18 (depends on 15) The method of claim 15, wherein the sealing comprises extending the thermal interfacial material to an axial end surface of the rotor core and covering the extended thermal interfacial material with a radially-extending portion of a structure coupled to the same axial end of the rotor core. ### Claim 19 (depends on 14) The method of claim 14, further comprising machining the outer surface of the hub member to thereby substantially remove surface irregularities. ### Claim 20 (depends on 14) The method of claim 14, wherein the coating includes radially biasing the thermal interfacial material against the surface being coated.