# US 2016/0355084 A1 · Wheel drive motor and in-wheel motor drive assembly > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2016/0355084 A1 - Document ID: US20160355084A1 - Status: Published application - Kind: A1 - Application number: 15/116,521 - Filed: 2015-01-27 - Published: 2016-12-08 - Earliest claimed: 2014-02-18 - Assignees: Ntn Corporation - Applicants: Ntn Corporation - Inventors: Tomohisa UOZUMI; Masaru KURODA; Kenichi SUZUKI - Web page: https://patentgrep.com/patent/US20160355084A1 ## CPC - B60K 7/0007: {the motor being electric} - B60B 27/00: Hubs (non-metallic B60B5/00; of high resiliency B60B9/00) - B60K 17/043: {Transmission unit disposed in on near the vehicle wheel, or between the differential gear unit and the wheel} - H02K 1/30: using intermediate parts, e.g. spiders - H02K 1/32: with channels or ducts for flow of cooling medium - H02K 7/006: {Structural association of a motor or generator with the drive train of a motor vehicle} - H02K 7/08: Structural association with bearings - H02K 7/116: with gears - H02K 9/19: for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil - H02K 2213/03: Machines characterised by numerical values, ranges, mathematical expressions or similar information - Y02T 10/64: Electric machine technologies in electromobility - B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES - B60B: VEHICLE WHEELS (making wheels or wheel parts by rolling B21H1/00, by forging, hammering or pressing B21K1/28); CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract The wheel drive motor according to the invention includes a motor shaft (35) having a large diameter portion (35d) located at a central part in the axial direction and a small diameter portion (35b) located on a first side in the axial direction, a bearing (36b) rotatably supporting the small diameter portion (35b), and a rotor (24) secured to an outer circumferential surface (35j) of the large diameter portion (35d). An end part (24p) of the rotor (24) located on the first side in the axial direction projects over an end face (35e) of the large diameter portion (35d) located on the first side in the axial direction toward the side on which the small diameter portion (35b) is. ## Claims ### Claim 1 A wheel drive motor, comprising: a motor shaft, for outputting drive force to rotate a wheel, extending in an axial direction and including a large diameter portion located at a central part in the axial direction and a small diameter portion located on a first side in the axial direction, the small diameter portion having a diameter smaller than that of the large diameter portion, a bearing rotatably supporting the small diameter portion, and a rotor secured to an outer circumferential surface of the large diameter portion and facing a stator, wherein an end part of the rotor located on the first side in the axial direction projects over an end face of the large diameter portion located on the first side in the axial direction toward the side on which the small diameter portion is. ### Claim 2 (depends on 1) The wheel drive motor according to claim 1, wherein the large diameter portion has an outer diameter greater than the outer diameter of the bearing, and the end part of the rotor projects over an end part of the bearing located on a second side in the axial direction toward the side on which the small diameter portion is. ### Claim 3 (depends on 2) The wheel drive motor according to claim 2, wherein the outer circumferential surface of the large diameter portion includes a large diameter portion's fitting surface that fits with a radially inner part of the rotor, the small diameter portion has a small diameter portion's fitting surface on its outer circumference, the small diameter portion's fitting surface fitting with an inner ring member of the bearing, and the positions of the large diameter portion's fitting surface and the small diameter portion's fitting surface are adjacent to each other so as not to overlap with each other in the axial direction. ### Claim 4 (depends on 1) The wheel drive motor according to claim 1, further comprising an end member that is fixedly attached to the large diameter portion, projects from the end face of the large diameter portion located on the first side in the axial direction, and covers an end face of the rotor located on the first side in the axial direction. ### Claim 5 (depends on 4) The wheel drive motor according to claim 4, wherein the end member is positioned to be coaxial with the motor shaft at an attachment position on the large diameter portion, and the end member includes an outer circumferential fitting surface that fits with a radially inner part of the end part_of the rotor located on the first side in the axial direction. ### Claim 6 (depends on 4) The wheel drive motor according to claim 4, further comprising an edge member that is interposed between the end member and the end face of the rotor located on the first side in the axial direction, and includes a lubricating oil passage. ### Claim 7 (depends on 1) An in-wheel motor drive assembly comprising: a wheel drive motor according to claim 1, a speed reducing section including an input shaft coupled to the motor shaft and an output shaft reducing the rotational speed of the input shaft and outputting it, and a wheel hub bearing section including a wheel hub coupled to the output shaft.