# US 2019/0173349 A1 · Brushless motor for a power tool > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0173349 A1 - Document ID: US20190173349A1 - Status: Published application - Kind: A1 - Application number: 16/267,874 - Filed: 2019-02-05 - Published: 2019-06-06 - Earliest claimed: 2014-11-25 - Assignees: Black & Decker Inc. - Applicants: Black & Decker Inc. - Inventors: David J. Smith; David E. Gillespie; Merritt J. Tennison - Web page: https://patentgrep.com/patent/US20190173349A1 ## CPC - H02K 5/15: Mounting arrangements for bearing-shields or end plates - H02K 1/276: Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM] - H02K 1/2766: {having a flux concentration effect} - H02K 1/28: Means for mounting or fastening rotating magnetic parts on to, or to, the rotor structures - H02K 5/16: Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields (magnetic bearings H02K7/09) - H02K 5/24: specially adapted for suppression or reduction of noise or vibrations - H02K 7/145: {Hand-held machine tool} - H02K 11/215: Magnetic effect devices, e.g. Hall-effect or magneto-resistive elements - H02K 2213/12: Machines characterised by the modularity of some components - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) ## Abstract An electric brushless DC (BLDC) motor includes a stator and a rotor. The rotor includes a rotor shaft, a rotor core, a bearing, and a sense magnet ring. And end cap is radially oriented with respect to the rotor shaft and securely disposed adjacent the stator, the end cap having a first surface facing the stator, a second surface facing away from the stator, a bearing pocket centrally disposed to receive the at least one bearing of the rotor therein to support the rotor, and at least two retention features projecting from the first surface at a distance with respect to one another to form a lateral gap therebetween. A positional sensor board is radially received from a peripheral side of the end cap in contact with the first surface of the end cap and within the lateral gap between the retention features of the end cap. ## Claims ### Claim 1 A power tool having a housing and an electric brushless DC (BLDC) motor housed inside the housing, the motor comprising: a stator having a plurality of windings; a rotor in rotatable interaction with the stator, the rotor comprising a rotor shaft, a rotor core rotatably mounted on the rotor shaft and housing a plurality of rotor magnets therein, at least one bearing mounted on the rotor shaft, and a sense magnet ring rotatable with the rotor core; an end cap radially oriented with respect to the rotor shaft and securely disposed adjacent the stator, the end cap having a first surface facing the stator, a second surface facing away from the stator, a bearing pocket centrally disposed to receive the at least one bearing of the rotor therein to support the rotor, and at least two retention features projecting from the first surface at a distance with respect to one another to form a lateral gap therebetween; a positional sensor board having a plurality of positional sensors mounted thereon, the positional sensor board being radially received from a peripheral side of the end cap in contact with the first surface of the end cap and within the lateral gap between the retention features of the end cap, the distance between the retention features being sized to securely receive the positional sensor board therethrough to support the positional sensor board on the first surface of the end cap and position the plurality of positional sensors in close proximity to the sense magnet ring. ### Claim 2 (depends on 1) The power tool of claim 1, further comprising a fan mounted on the rotor shaft to rotate therewith and generate an airflow through the motor. ### Claim 3 (depends on 2) The power tool of claim 2, wherein the end cap comprises a plurality of air vents disposed around the bearing pocket to allow passage of the airflow generated by the fan. ### Claim 4 (depends on 3) The power tool of claim 3, wherein the plurality of air vents is disposed around three sides of the bearing pocket and the positional sensor is positioned on a fourth side of the bearing pocket. ### Claim 5 (depends on 3) The power tool of claim 3, wherein the bearing pocket comprises a through-hole through the end cap through which the rotor shaft extends. ### Claim 6 (depends on 5) The power tool of claim 5, wherein the fan is mounted on the shaft facing the second surface of the end cap. ### Claim 7 (depends on 1) The power tool of claim 1, wherein the plurality of positional sensors comprises a plurality of Hall sensors mounted on a first surface of the positional sensor board facing the sense magnet, a second surface of the positional sensor board being in contact with the end cap. ### Claim 8 (depends on 1) The power tool of claim 1, wherein the positional sensor board includes two side edges that engage the retention features, and a radially-inner edge that includes a curved profile to be disposed around an outer periphery of the bearing pocket. ### Claim 9 (depends on 8) The power tool of claim 8, wherein the positional sensor board further includes a radially-outer edge that protrudes outside a periphery of the end cap, the hall board comprising a hall terminal disposed at or near the radially-outer edge. ### Claim 10 (depends on 9) The power tool of claim 9, further comprising a control unit having a controller, the control unit being coupled to the hall terminal via a plurality of wires. ### Claim 11 (depends on 1) The power tool of claim 1, further comprising a motor housing that houses the stator therein, wherein the end cap is integrally formed as a back plate of the motor housing. ### Claim 12 An electric brushless DC (BLDC) motor comprising: a stator having a plurality of windings; a rotor in rotatable interaction with the stator, the rotor comprising a rotor shaft, a rotor core rotatably mounted on the rotor shaft and housing a plurality of rotor magnets therein, at least one bearing mounted on the rotor shaft, and a sense magnet ring rotatable with the rotor core; an end cap radially oriented with respect to the rotor shaft and securely disposed adjacent the stator, the end cap having a first surface facing the stator, a second surface facing away from the stator, a bearing pocket centrally disposed to receive the at least one bearing of the rotor therein to support the rotor, and at least two retention features projecting from the first surface at a distance with respect to one another to form a lateral gap therebetween; a positional sensor board having a plurality of positional sensors mounted thereon, the positional sensor board being radially received from a peripheral side of the end cap in contact with the first surface of the end cap and within the lateral gap between the retention features of the end cap, the distance between the retention features being sized to securely receive the positional sensor board therethrough to support the positional sensor board on the first surface of the end cap and position the plurality of positional sensors in close proximity to the sense magnet ring. ### Claim 13 (depends on 12) The electric motor of claim 12, further comprising a fan mounted on the rotor shaft to rotate therewith and generate an airflow through the motor. ### Claim 14 (depends on 13) The electric motor of claim 13, wherein the end cap comprises a plurality of air vents disposed around the bearing pocket to allow passage of the airflow generated by the fan. ### Claim 15 (depends on 14) The electric motor of claim 14, wherein the plurality of air vents is disposed around three sides of the bearing pocket and the positional sensor is positioned on a fourth side of the bearing pocket. ### Claim 16 (depends on 14) The electric motor of claim 14, wherein the bearing pocket comprises a through-hole through the end cap through which the rotor shaft extends. ### Claim 17 (depends on 16) The electric motor of claim 16, wherein the fan is mounted on the shaft facing the second surface of the end cap. ### Claim 18 (depends on 12) The electric motor of claim 12, wherein the plurality of positional sensors comprises a plurality of Hall sensors mounted on a first surface of the positional sensor board facing the sense magnet, a second surface of the positional sensor board being in contact with the end cap. ### Claim 19 (depends on 12) The electric motor of claim 12, wherein the positional sensor board includes two side edges that engage the retention features, and a radially-inner edge that includes a curved profile to be disposed around an outer periphery of the bearing pocket. ### Claim 20 (depends on 19) The electric motor of claim 19, wherein the positional sensor board further includes a radially-outer edge that protrudes outside a periphery of the end cap, the hall board comprising a hall terminal disposed at or near the radially-outer edge. ### Claim 21 (depends on 20) The electric motor of claim 20, further comprising a control unit having a controller, the control unit being coupled to the hall terminal via a plurality of wires. ### Claim 22 (depends on 12) The electric motor of claim 12, further comprising a motor housing that houses the stator therein, wherein the end cap is integrally formed as a back plate of the motor housing.