# US 2014/0197701 A1 · Electric motor stator housing interference gap reducing method and apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0197701 A1 - Document ID: US20140197701A1 - Status: Published application - Kind: A1 - Application number: 13/744,147 - Filed: 2013-01-17 - Published: 2014-07-17 - Earliest claimed: 2013-01-17 - Assignees: Remy Technologies, L.L.C. - Applicants: Remy Technologies, LLC - Inventors: Noman Hossain; Bradley D. Chamberlin - Web page: https://patentgrep.com/patent/US20140197701A1 ## CPC - H02K 9/223: {Heat bridges} - H02K 1/185: {to outer stators} - 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 - Y10T 29/49009: Dynamoelectric machine - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A cooling system of an electric machine includes a stator core, a housing, and a thermal interfacial material interposed between complementary mating surfaces of the stator core and the housing for substantially eliminating air gaps therebetween. A method of cooling an electric machine having a housing and a stator includes placing a thermal interfacial material onto a heat transfer interface between the stator and the housing, whereby the thermal interfacial material reduces contact resistance at the heat transfer interface. A method of cooling a stator of an electric machine includes heating a housing having a radially inner surface, coating a radially outer surface of the stator and/or the radially inner surface of the housing with a thermal interfacial material, and inserting the stator into the heated housing, whereby the thermal interfacial material is interposed between the inner surface of the housing and the outer surface of the stator. ## Claims ### Claim 1 A cooling system of an electric machine, comprising: a stator core; a housing; and a thermal interfacial material interposed between complementary mating surfaces of the stator core and the housing for substantially eliminating air gaps therebetween. ### Claim 2 (depends on 1) The cooling system of claim 1, wherein the housing includes a cooling jacket wall, and wherein the thermal interfacial material is interposed between complementary mating surfaces of the stator and the cooling jacket wall. ### Claim 3 (depends on 2) The cooling system of claim 2, further comprising seals at axial ends of the thermal interfacial material for enclosing the material between the complementary mating surfaces. ### Claim 4 (depends on 3) The cooling system of claim 3, wherein the seals include epoxy. ### Claim 5 (depends on 3) The cooling system of claim 3, wherein the enclosed thermal interfacial material comprises liquid. ### Claim 6 (depends on 1) The cooling system of claim 1, wherein the complementary mating surfaces have an interference fit. ### Claim 7 (depends on 1) The cooling system of claim 1, wherein the thermal interfacial material has a nominal thickness between 0.02 mm and 0.5 mm. ### Claim 8 (depends on 1) The cooling system of claim 1, wherein the thermal interfacial material is substantially uncurable thermal grease. ### Claim 9 (depends on 1) The cooling system of claim 1, wherein the respective mating surfaces of the stator core and the housing are substantially annular. ### Claim 10 A method of cooling an electric machine having a housing and a stator, comprising placing a thermal interfacial material onto a heat transfer interface between the stator and the housing, whereby the thermal interfacial material reduces contact resistance at the heat transfer interface. ### Claim 11 (depends on 10) The method of claim 10, further comprising: heating and thereby expanding the housing; cooling and thereby shrinking the stator; installing the cooled stator within the heated housing; and cooling the housing so that the stator is interference fit therein. ### Claim 12 (depends on 10) The method of claim 10, wherein the housing comprises a cooling jacket having a radially inner surface that abuts a radially outer surface of the stator to form the heat transfer interface. ### Claim 13 (depends on 10) The method of claim 10, further comprising, prior to the placing of the thermal interfacial material, machining a radially outer surface of the stator to substantially reduce surface irregularities. ### Claim 14 A method of cooling a stator of an electric machine, comprising: heating a housing having a radially inner surface; coating at least one of a radially outer surface of the stator and the radially inner surface of the housing with a thermal interfacial material; and inserting the stator into the heated housing; whereby the thermal interfacial material is interposed between the inner surface of the housing and the outer surface of the stator. ### Claim 15 (depends on 14) The method of claim 14, further comprising sealing the stator to the housing, 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 filling a space of the electric machine with potting material. ### Claim 19 (depends on 14) The method of claim 14, further comprising machining the outer surface of the stator 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.