# US 10,770,940 B2 · Modular rotors for axial flux electric machines > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,770,940 B2 - Document ID: US10770940B2 - Status: Granted - Kind: B2 - Application number: 15/420,953 - Filed: 2017-01-31 - Published: 2018-08-02 - Granted: 2020-09-08 - Earliest claimed: 2017-01-31 - Assignees: Regal Beloit Australia Pty Ltd - Applicants: Regal Beloit Australia, PTY., Ltd. - Inventors: Mark Thiele; Greg Heins; Matthew J. Turner; Dean James Patterson - Web page: https://patentgrep.com/patent/US10770940B2 ## CPC - H02K 1/2795: the rotor consisting of two or more circumferentially positioned magnets - H02K 1/14: Stator cores with salient poles - H02K 1/143: {of the horse-shoe type} - H02K 1/146: {consisting of a generally annular yoke with salient poles} - H02K 1/148: {Sectional cores (H02K1/141 takes precedence)} - H02K 1/182: {to stators axially facing the rotor, i.e. with axial or conical air gap} - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) ## Abstract A rotor module for an axial flux electric machine includes a back iron segment configured for attachment to a rotor base and a plurality of permanent magnets attached to the back iron segment. The back iron segment has a length less than a circumference of the rotor base. Each permanent magnet attached to the back iron segment has an opposite magnetic pole orientation from each adjacent permanent magnet attached to the back iron segment. A plurality of rotor modules is coupled to the rotor base to form a rotor for the axial flux electric machine. ## Claims ### Claim 1 A rotor module for an axial flux electric machine, said rotor module comprising: a back iron segment configured for attachment to a rotor base, said back iron segment having a length less than a circumference of said rotor base, said back iron segment having a tab; a plurality of permanent magnets attached to said back iron segment, each permanent magnet of said plurality of permanent magnets having a face surface, wherein said each permanent magnet has an opposite magnetic pole orientation from each adjacent permanent magnet of said plurality of permanent magnets attached to said back iron segment; and a magnet retainer attached to said back iron segment, said magnet retainer including a plurality of slots aligned with said plurality of permanent magnets such that said face surfaces of said plurality of permanent magnets are not covered by said magnet retainer, said plurality of slots configured to receive said plurality of permanent magnets and position said plurality of permanent magnets on said back iron segment, said magnet retainer having a length less than the circumference of said rotor base, said magnet retainer defining an opening configured to receive said tab of an adjacent back iron segment. ### Claim 2 (depends on 1) The rotor module in accordance with claim 1, wherein said plurality of permanent magnets are positioned adjacent each other in a substantially straight line on said back iron segment, wherein said back iron segment has a substantially straight length. ### Claim 3 (depends on 1) The rotor module in accordance with claim 1, wherein said plurality of permanent magnets are positioned adjacent each other to define an arc, wherein said back iron segment is curved along the arc. ### Claim 4 (depends on 3) The rotor module in accordance with claim 3, wherein the arc is defined by a radius of said rotor base. ### Claim 5 (depends on 3) The rotor module in accordance with claim 3, wherein said plurality of permanent magnets have a trapezoidal shape. ### Claim 6 (depends on 1) The rotor module in accordance with claim 1, wherein said plurality of permanent magnets comprises an even number of permanent magnets. ### Claim 7 (depends on 1) The rotor module in accordance with claim 1, wherein said back iron segment comprises at least one of laminated steel, a soft magnetic composite (SMC) material, and ferromagnetic steel. ### Claim 8 (depends on 1) The rotor module of claim 1, wherein said magnet retainer is further configured to secure said plurality of permanent magnets to the back iron segment. ### Claim 9 A rotor for an axial flux electric machine, said rotor comprising: a rotor base having a face surface and a circumference around said face surface; and at least one rotor module attached to said rotor base, said at least one rotor module comprising: a back iron segment attached to said face surface of said rotor base, said back iron segment having a length less than a circumference of said rotor base; a plurality of permanent magnets attached to said back iron segment, each permanent magnet of said plurality of permanent magnets having a face surface, wherein said each permanent magnet has an opposite magnetic pole from each adjacent permanent magnet of said plurality of permanent magnets attached to said back iron segment; and a magnet retainer attached directly to said back iron segment and said rotor base, said magnet retainer including a plurality of slots aligned with said plurality of permanent magnets such that said face surfaces of said plurality of permanent magnets are not covered by said magnet retainer, said plurality of slots configured to receive said plurality of permanent magnets and position said plurality of permanent magnets on said back iron segment, said magnet retainer having a length less than the circumference of said rotor base. ### Claim 10 (depends on 9) The rotor in accordance with claim 9, wherein said plurality of permanent magnets are positioned adjacent to each other in a substantially straight line on said back iron segment, wherein said back iron segment has a substantially straight length. ### Claim 11 (depends on 9) The rotor in accordance with claim 9, wherein said plurality of permanent magnets are positioned adjacent to each other to define an arc, wherein said back iron segment is curved along the arc. ### Claim 12 (depends on 11) The rotor in accordance with claim 11, wherein the arc is substantially the same as an arc defined by an outer edge of said rotor base. ### Claim 13 (depends on 9) The rotor in accordance with claim 9, wherein said at least one rotor module comprises a plurality of circumferentially arranged modules. ### Claim 14 (depends on 13) The rotor in accordance with claim 13, wherein said plurality of rotor modules are curved and aligned with an outer edge of said rotor base. ### Claim 15 (depends on 13) The rotor in accordance with claim 13, wherein each rotor module of said plurality of rotor modules has a substantially straight length, wherein said plurality of rotor modules are angled relative to each other to approximate an arc defined by an outer edge of said rotor base. ### Claim 16 (depends on 9) The rotor in accordance with claim 9, wherein said rotor base comprises a nonmagnetic material. ### Claim 17 (depends on 16) The rotor in accordance with claim 16, wherein said nonmagnetic material includes at least one of aluminum, plastic, and stainless steel. ### Claim 18 An axial flux electric machine comprising: a stator; and a rotor positioned adjacent said stator, said rotor comprising: a rotor base having a face surface and a circumference around said face surface; and at least one rotor module attached to said rotor base, said at least one rotor module comprising: a back iron segment attached to said face surface of said rotor base, said back iron segment having a length less than a circumference of said rotor base; a plurality of permanent magnets attached to said back iron segment, each permanent magnet of said plurality of permanent magnets having a face surface, wherein said each permanent magnet has an opposite magnetic pole from each adjacent permanent magnet of said plurality of permanent magnets attached to said back iron segment; and a magnet retainer attached directly to said back iron segment and said rotor base, said magnet retainer including a plurality of slots aligned with said plurality of permanent magnets such that said face surfaces of said plurality of permanent magnets are not covered by said magnet retainer, said plurality of slots configured to receive said plurality of permanent magnets and position said plurality of permanent magnets on said back iron segment, said magnet retainer having a length less than the circumference of said rotor base. ### Claim 19 (depends on 18) The axial flux electric machine in accordance with claim 18, wherein said stator is a modular stator having a plurality of stator modules, each stator module comprising a core having at least one winding disposed thereon. ### Claim 20 (depends on 19) The axial flux electric machine in accordance with claim 19, wherein a number of said plurality of permanent magnets is equal to a number of windings of said plurality of stator modules.