# US 10,770,938 B2 · Electronically commutated electric motor with two rotor cores > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,770,938 B2 - Document ID: US10770938B2 - Status: Granted - Kind: B2 - Application number: 15/679,752 - Filed: 2017-08-17 - Published: 2018-03-01 - Granted: 2020-09-08 - Earliest claimed: 2016-08-23 - Assignees: Lakeview Innovation Ltd. - Applicants: Lakeview Innovation Ltd. - Inventors: Stefan Imfeld - Web page: https://patentgrep.com/patent/US10770938B2 ## CPC - H02K 1/2773: {consisting of tangentially magnetized radial magnets} - H02K 1/28: Means for mounting or fastening rotating magnetic parts on to, or to, the rotor structures - H02K 29/08: using magnetic effect devices, e.g. Hall-plates, magneto-resistors (H02K29/12 takes precedence) - H02K 11/215: Magnetic effect devices, e.g. Hall-effect or magneto-resistive elements - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) ## Abstract An electronically commutated electric motor is disclosed with a stator, a rotor rotatably mounted relative to the stator, and at least one sensor for scanning a magnetic field that co-rotates with the rotor, where the stator includes a stator winding and a magnetically soft stator core, where the rotor includes several permanent magnets arranged distributed in the circumferential direction of the rotor as well as a first magnetically soft rotor core for the permanent magnets, and where the permanent magnets, together with the first magnetically soft rotor core, generate a rotor magnetic field which, for operating the electric motor, interacts with the stator magnetic field of the stator generated by the stator winding and the stator core. A second magnetically soft rotor core adjoins the first magnetically soft rotor core in the axial direction of the rotor. A non-magnetic separator element is arranged in the axial direction, where the permanent magnets extend over the first magnetically soft rotor core, the non-magnetic separator element and the second magnetically soft rotor core. ## Claims ### Claim 1 Electronically commutated electric motor comprising: a stator, a rotor rotatably mounted relative to said stator; and at least one sensor for scanning a magnetic field that co-rotates with said rotor, where said stator includes a stator winding and a magnetically soft stator core, where said rotor includes, several permanent magnets arranged distributed in the circumferential direction of said rotor as well as a first magnetically soft rotor core for said permanent magnets, and where said permanent magnets, together with said first magnetically soft rotor core, are configured to generate a rotor magnetic field which, for operating said electric motor, will interact with the stator magnetic field of said stator when generated by said stator winding and said stator core, wherein said rotor has a second magnetically soft rotor core which adjoins said first magnetically soft rotor core in the axial direction of said rotor, where a non-magnetic separator element is arranged in the axial direction between said first magnetically soft rotor core and said second magnetically soft rotor core, the thickness of the non-magnetic separator element measured in the axial direction of said rotor is at least 10% of the outer diameter of the rotor, where said permanent magnets extend in the axial direction over said first magnetically soft rotor core, said non-magnetic separator element and said second magnetically soft rotor core, and where the magnetic field scanned by said sensor will be generated as a control magnetic field by said permanent magnets together with said second magnetically soft rotor core, wherein said at least one sensor faces an axial face end of the second magnetically soft rotor core. ### Claim 2 (depends on 1) Electronically commutated electric motor according to claim 1, wherein said second magnetically soft rotor core is arranged in the axial direction outside said magnetically soft stator core. ### Claim 3 (depends on 2) Electronically commutated electric motor according to claim 2, wherein said first magnetically soft rotor core is arranged in the axial direction a same position as said magnetically soft stator core. ### Claim 4 (depends on 3) Electronically commutated electric motor according to claim 3, wherein said first magnetically soft rotor core and said magnetically soft stator core have a same axial length. ### Claim 5 (depends on 4) Electronically commutated electric motor according to claim 4, wherein said second magnetically soft rotor core terminates substantially with winding heads of said stator winding in the axial direction. ### Claim 6 (depends on 5) Electronically commutated electric motor according to claim 5, wherein said non-magnetic separator element is a plastic disk. ### Claim 7 (depends on 6) Electronically commutated electric motor according to claim 6, wherein said first magnetically soft rotor core, said second magnetically soft rotor core, and said non-magnetic separator element exhibit substantially the same cross-sectional geometry. ### Claim 8 (depends on 7) Electronically commutated electric motor claim 7, wherein said permanent magnets are received in grooves formed in said first magnetically soft rotor core, said second magnetically soft rotor core, and said non-magnetic separator element. ### Claim 9 (depends on 8) Electronically commutated electric motor claim 8, wherein said first magnetically soft rotor core and said second magnetically soft rotor core are each composed of magnetically soft, punched and stacked metal sheets insulated on both sides. ### Claim 10 (depends on 7) Electronically commutated electric motor according to claim 7, wherein said first magnetically soft rotor core and said second magnetically soft rotor core are each composed of magnetically soft, punched and stacked metal sheets insulated on both sides. ### Claim 11 (depends on 2) Electronically commutated electric motor according to claim 2, wherein said second magnetically soft rotor core terminates substantially with winding heads of said stator winding in the axial direction. ### Claim 12 (depends on 1) Electronically commutated electric motor according to claim 1, wherein said non-magnetic separator element is a plastic disk. ### Claim 13 (depends on 1) Electronically commutated electric motor according to claim 1, wherein said first magnetically soft rotor core, said second magnetically soft rotor core, and said non-magnetic separator element exhibit substantially the same cross-sectional geometry. ### Claim 14 (depends on 1) Electronically commutated electric motor according to claim 1, wherein said permanent magnets are received in grooves formed in said first magnetically soft rotor core, said second magnetically soft rotor core, and said non-magnetic separator element. ### Claim 15 (depends on 1) Electronically commutated electric motor according to claim 1, wherein said first magnetically soft rotor core and said second magnetically soft rotor core are each composed of magnetically soft, punched and stacked metal sheets insulated on both sides. ### Claim 16 (depends on 1) Electronically commutated electric motor according to claim 1, wherein said rotor has a 4-pole, 8-pole, 10-pole, 14-pole or 16-pole design. ### Claim 17 (depends on 1) Electronically commutated electric motor according to claim 1, wherein said permanent magnets are magnetized in the tangential direction of said rotor. ### Claim 18 (depends on 1) Electronically commutated electric motor according to claim 1, wherein said at least one sensor for scanning the control magnetic field is a Hall sensor, where said Hall sensor is arranged on a side of a printed circuit board facing said second magnetically soft rotor core in the axial direction. ### Claim 19 (depends on 1) Electronically commutated electric motor according to claim 1, wherein said electric motor is a small electric motor having a diameter of less than 60 mm. ### Claim 20 Method for manufacturing a rotor for an electronically commutated electric motor, the electric motor having a stator where the rotor is rotatably mounted relative to said stator, and at least one sensor for scanning a magnetic field that co-rotates with said rotor, where said stator includes a stator winding and a magnetically soft stator core, and said rotor includes, several permanent magnets arranged distributed in the circumferential direction of said rotor as well as a first magnetically soft rotor core for said permanent magnets, wherein said rotor has a second magnetically soft rotor core which adjoins said first magnetically soft rotor core in the axial direction of said rotor, wherein a non-magnetic separator element is arranged in the axial direction between said first magnetically soft rotor core and said second magnetically soft rotor core, and wherein the thickness of the non-magnetic separator element measured in the axial direction of said rotor is at least 10% of the outer diameter of the rotor, wherein said at least one sensor faces an axial face end of the second magnetically soft rotor core the method comprising: providing said rotor has a shaft onto which, in a first step, said non-magnetic separator element provided with a center through-bore is slipped; subsequently, said first magnetically soft rotor core and said second magnetically soft rotor core, also having corresponding center through-bores, are slipped onto said shaft; inserting said permanent magnets into corresponding recesses of said first and said second magnetically soft rotor cores and of a non-magnetic separator element, and casting said rotor with an anaerobic potting compound or with adhesive.