# US 10,312,754 B2 · Interior permanent magnet motor and rotor structure therefore > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,312,754 B2 - Document ID: US10312754B2 - Status: Granted - Kind: B2 - Application number: 15/121,918 - Filed: 2015-03-02 - Published: 2017-03-09 - Granted: 2019-06-04 - Earliest claimed: 2014-02-28 - Assignees: TRW Inc. - Applicants: TRW Limited - Inventors: John Leslie Gorton; David Julian Moule; Gary Webb - Web page: https://patentgrep.com/patent/US10312754B2 ## CPC - H02K 1/276: Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM] - H02K 15/03: having permanent magnets - 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 structure for an interior permanent magnet electric motor comprising: A laminated rotor core which comprises stack of thin plates, the stack having a first end and a second end, each plate in the stack including at least one window which is aligned with a corresponding window of an adjacent plate so that the window together form an elongate pocket that extends along at least a part of the length of the core starting at a first end of the core, and at least one permanent magnet located in the pocket. At least one plate at the first end of the stack includes an integral retention feature which projects away from a main body of the plate to project above the window in the plate and which engages the first end of the magnet thereby to retain the magnet in the pocket. ## Claims ### Claim 1 A rotor structure for an interior permanent magnet electric motor comprising: a laminated rotor core which comprises at least one stack of thin plates, the stack having a first end and a second end, each plate in the stack including at least one window which is aligned with a corresponding window of an adjacent plate so that the windows together form an elongate pocket that extends along at least a part of a length of the core starting at a first end of the core, and at least one permanent magnet located in the pocket, wherein at least one plate at the first end of the stack includes an integral retention feature which extends away from a main body of the plate to project above the window in the plate and which engages an end of the magnet thereby to retain the magnet in the pocket. ### Claim 2 (depends on 1) The rotor structure according to claim 1 in which the at least one plate is an outermost plate of the stack. ### Claim 3 (depends on 1) The rotor structure according to claim 1 in which the retention feature retains the magnet so that an end face of the magnet is substantially flush with a face of the main body of an endmost plate of the stack that faces away from the stack. ### Claim 4 (depends on 1) The rotor structure according to claim 1 in which the main body of the plate comprises a substantially flat plate having opposed upper and lower planar faces. ### Claim 5 (depends on 1) The rotor structure according to claim 1 in which the retention feature comprises a deformable tab which is deformed out of a plane of the main body by the magnet during assembly so that the tab applies a compressive force to the magnet biasing it in a direction away from the first end of the stack. ### Claim 6 (depends on 1) The rotor structure according to claim 1 in which the retention feature comprises a rigid protruding edge of the plate which overhangs the window and is connected to the main body of the plate by a stepped shoulder that is formed by pressing or stamping or planishing of the plate during production. ### Claim 7 (depends on 1) The rotor structure according to claim 1 in which the magnet is the same length as the stacked main bodies of the plates. ### Claim 8 (depends on 1) The rotor structure according to claim 1 in which the rotor core comprises two or more stacks of plates. ### Claim 9 (depends on 1) An interior permanent magnet motor including a rotor structure according to claim 1. ### Claim 10 A method of assembling a rotor structure for an interior permanent magnet electric motor comprising: providing a plurality of thin plates, each having a main body with two opposing major faces, a central opening and at least one window; fixing a set of the plates together to form a laminated rotor core having a first end and a second end, the at least one window in each plate being aligned with a corresponding window of an adjacent plate so that the windows together form an elongate pocket that extends along at least a part of the length of the core starting at a first end of the core, locating a permanent magnet in the pocket that has a first end that protrudes slightly from the first end of the stack; and securing a further plate to the first end of the stack that includes an integral retention feature which projects away from the main body of the plate to project above a window in the plate that receives the protruding first end of the magnet so that the retention means engages the first end of the magnet thereby to retain the magnet in the pocket. ### Claim 11 (depends on 10) The method according to claim 10 which further comprises adding a second additional plate to an opposite, second, end of the stack, the second additional plate also including an integral retention feature which projects away from the main body of the plate to project above a window in the plate that receives the protruding first end of the magnet so that the retention means engages the first end of the magnet thereby to retain the magnet in the pocket. ### Claim 12 (depends on 11) The method according to claim 11 which comprises providing a retention feature on the second additional plate that lies at least partially within the window prior to assembly and which is resiliently deformed on assembly as the magnet enters the window and pushes the retention feature out of the plane of the plate.