# US 10,309,458 B2 · Brushless motor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,309,458 B2 - Document ID: US10309458B2 - Status: Granted - Kind: B2 - Application number: 15/287,029 - Filed: 2016-10-06 - Published: 2017-06-15 - Granted: 2019-06-04 - Earliest claimed: 2015-12-10 - Assignees: Tokyo Parts Industrial Co., Ltd. - Applicants: Tokyo Parts Industrial Co., Ltd. - Inventors: Masahisa Tuchiya - Web page: https://patentgrep.com/patent/US10309458B2 ## CPC - F16C 33/128: {Porous bearings, e.g. bushes of sintered alloy} - F16C 17/107: {with at least one surface for radial load and at least one surface for axial load} - F16C 33/104: {in a porous body, e.g. oil impregnated sintered sleeve} - H02K 5/1675: {radially supporting the rotary shaft at only one end of the rotor (H02K5/1677 takes precedence)} - F16C 2226/12: by press-fit, e.g. plug-in - F16C 2380/26: Dynamo-electric machines or combinations therewith, e.g. electro-motors and generators - F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) ## Abstract A double bearing comprising an inner bearing and an outer bearing, which has a greater oil content than the inner bearing, is used as a bearing for a brushless motor. The inner bearing has an upper bearing part, a lower bearing part, and a central relief part. Gaps are provided between the bearing parts and a bearing housing, along the entire axial length of all of the bearing parts of the inner bearing. ## Claims ### Claim 1 A brushless motor comprising: a rotor having a shaft; a cylindrical bearing that supports the shaft in a radial direction with oil as an intermediary medium; and a bearing housing that is open at a top end, at an interior of which the bearing is fastened, wherein: the cylindrical bearing has an inner bearing made from a porous oil-impregnated material and an outer bearing made form a porous oil-impregnated material, mounted on an outer circumferential face of the inner bearing; the inner bearing has a bearing portion formed protruding in a radially inward direction, so as to rotatably support the radial direction of the shaft; the oil content of the outer bearing is greater than that of the inner bearing and so that the outer bearing supplies oil to the inner bearing; and a gap is provided between the bearing portion and the bearing housing located radially outward from the bearing portion, along an entire axial length of the bearing portion. ### Claim 2 (depends on 1) The brushless motor according to claim 1, wherein the bearing portion comprises an upper bearing portion provided at a top of the inner bearing, and a lower bearing provided at a bottom of the inner bearing. ### Claim 3 (depends on 2) The brushless motor according to claim 2, wherein the gap is provided between the outer bearing and the bearing housing located radially outward from the upper bearing portion, along the entire axial length of the upper bearing portion, and the gap is provided between the lower bearing portion and the outer bearing located radially outward from the lower bearing portion, along the entire axial length of the lower bearing portion. ### Claim 4 (depends on 2) The brushless motor according to claim 2, wherein the gap is provided between the upper bearing portion and the outer bearing located radially outward from the upper bearing portion, along the entire axial length of the upper bearing portion, and the gap is provided between the outer bearing and the bearing housing located radially outward from the lower bearing portion, along the entire axial length of the lower bearing portion. ### Claim 5 (depends on 2) The brushless motor according to claim 2, wherein the gap is provided between the outer bearing and the bearing housing located radially outward from the upper bearing portion, along the entire axial length of the upper bearing portion, and the gap is provided between the outer bearing and the bearing housing located radially outward from the lower bearing portion, along the entire axial length of the lower bearing portion. ### Claim 6 (depends on 2) The brushless motor according to claim 2, wherein the gap is provided between the upper bearing portion and the outer bearing located radially outward from the upper bearing portion, along the entire axial length of the upper bearing portion, and the gap is provided between the lower bearing portion and the bearing housing located radially outward from the lower bearing portion, along the entire axial length of the lower bearing portion. ### Claim 7 (depends on 1) The brushless motor according to claim 1, wherein a groove communicating in the axial direction is provided between the outer circumferential face of the inner bearing and an inner circumferential face of the outer bearing. ### Claim 8 (depends on 1) The brushless motor according to claim 1, wherein a groove communicating in the axial direction is provided between an outer circumferential face of the outer bearing and an inner circumferential face of the bearing housing. ### Claim 9 (depends on 1) The brushless motor according to claim 1, wherein a groove communicating in the axial direction is provided between the outer circumferential face of the inner bearing and an inner circumferential face of the outer bearing, and a groove communicating in the axial direction is provided between an outer circumferential face of the outer bearing and an inner circumferential face of the bearing housing. ### Claim 10 (depends on 2) The brushless motor according to claim 2, wherein a groove communicating in the axial direction is provided between the outer circumferential face of the inner bearing and an inner circumferential face of the outer bearing. ### Claim 11 (depends on 2) The brushless motor according to claim 2, wherein a groove communicating in the axial direction is provided between an outer circumferential face of the outer bearing and an inner circumferential face of the bearing housing. ### Claim 12 (depends on 2) The brushless motor according to claim 2, wherein a groove communicating in the axial direction is provided between the outer circumferential face of the inner bearing and an inner circumferential face of the outer bearing, and a groove communicating in the axial direction is provided between an outer circumferential face of the outer bearing and an inner circumferential face of the bearing housing. ### Claim 13 (depends on 1) The brushless motor according to claim 1, wherein an annular groove is formed in an outer surface of the shaft in a portion of the shaft that protrudes from the inner bearing toward the open top end of the bearing housing. ### Claim 14 (depends on 13) The brushless motor according to claim 13, wherein an annular oil repellant member is mounted at the open top end of the bearing housing and a bottom face of the oil repellant member is at a higher axial position than a top edge of the annular groove. ### Claim 15 (depends on 2) The brushless motor according to claim 2, wherein an annular groove is formed in an outer surface of the shaft in a portion of the shaft that protrudes from the inner bearing toward the open top end of the bearing housing. ### Claim 16 (depends on 15) The brushless motor according to claim 15, wherein an annular oil repellant member is mounted at the open top end of the bearing housing and a bottom face of the oil repellant member is at a higher axial position than a top edge of the annular groove. ### Claim 17 (depends on 1) The brushless motor according to claim 1, wherein an entire axial length of the inner bearing extends within the bearing housing and an entire axial length of the outer bearing extends within the bearing housing, so that all of the cylindrical bearing is located within said interior of the bearing housing. ### Claim 18 (depends on 1) The brushless motor according to claim 1, wherein the bearing housing has a bottom end and said top end, and wherein an entire axial length of the inner bearing extends axially within the bearing housing between said bottom end and said top end, and an entire axial length of the outer bearing extends within the bearing housing between said bottom end and said top end.