# US 2017/0288499 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 2017/0288499 A1 - Document ID: US20170288499A1 - Status: Published application - Kind: A1 - Application number: 15/474,358 - Filed: 2017-03-30 - Published: 2017-10-05 - Earliest claimed: 2016-03-30 - Assignees: Milwaukee Electric Tool Corporation - Applicants: Milwaukee Electric Tool Corporation - Inventors: Andrew T. Beyerl; Keith Boulanger; Alex Huber; William A. Elger; Jeffrey M. Wackwitz - Web page: https://patentgrep.com/patent/US20170288499A1 ## CPC - H02K 7/145: {Hand-held machine tool} - B25F 5/00: Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for - B25F 5/006: {Vibration damping means} - B25F 5/008: {Cooling means} - H02K 1/185: {to outer stators} - H02K 1/187: {to inner stators} - H02K 5/15: Mounting arrangements for bearing-shields or end plates - H02K 5/161: {radially supporting the rotary shaft at both ends of the rotor (H02K5/165, H02K5/167, H02K5/173 take precedence)} - H02K 7/083: {radially supporting the rotary shaft at both ends of the rotor (H02K7/086, H02K7/09 take precedence)} - H02K 7/086: {radially supporting the rotor around a fixed spindle; radially supporting the rotor directly (H02K7/09 takes precedence)} - H02K 7/116: with gears - H02K 11/21: Devices for sensing speed or position, or actuated thereby (specially adapted for machines having non-mechanical commutating devices H02K29/06, H02K29/14) - H02K 21/14: with magnets rotating within the armatures - H02K 29/08: using magnetic effect devices, e.g. Hall-plates, magneto-resistors (H02K29/12 takes precedence) - H02K 9/06: with fans or impellers driven by the machine shaft - H02K 11/215: Magnetic effect devices, e.g. Hall-effect or magneto-resistive elements - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) - B25F: COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR {(machines or arrangements of machines for performing specified combinations of different metal-working operations not covered by a single other subclass B23P23/00 and subgroups)} ## Abstract A brushless direct current motor for a power tool. The motor includes a stator assembly including a stator core having stator laminations with an annular portion and inwardly extending stator teeth. The motor also includes a rotor assembly including a rotor core having rotor laminations and defining a central aperture that receives an output shaft. The rotor assembly also includes a rotor end cap on a first side of the rotor core having a bearing holder and defining a channel, wherein the channel is open on a side of the rotor end cap facing the rotor core. The motor further includes a bearing provided in the bearing holder that couples the rotor end cap to the output shaft and a position sensor board assembly provided in the channel of the rotor end cap and configured to provide position information of the rotor core to a motor controller. ## Claims ### Claim 1 A power tool, comprising: a housing; a controller within the housing; and a brushless motor within the housing and controlled by the controller, the brushless motor comprising: a stator assembly including a stator core having stator laminations with an annular portion and inwardly extending stator teeth, a rotor assembly including: a rotor core having rotor laminations and defining a central aperture that receives an output shaft; and a rotor end cap on a first side of the rotor core having a bearing holder and defining a channel, wherein the channel is open on a side of the rotor end cap facing the rotor core, a bearing provided in the bearing holder that couples the rotor end cap to the output shaft, and a position sensor board assembly provided in the channel of the rotor end cap and configured to provide position information of the rotor core to the controller. ### Claim 2 (depends on 1) The power tool of claim 1, wherein the channel is annular and has a diameter that is less than an inner diameter of the stator assembly. ### Claim 3 (depends on 1) The power tool of claim 1, wherein the position sensor board assembly includes a printed circuit board that is annular. ### Claim 4 (depends on 1) The power tool of claim 1, wherein the stator assembly includes a first stator end cap and a second stator end cap and the stator laminations are provided between the first and second stator end caps, and wherein the stator assembly defines a stator envelope in an axial direction extending between axial ends of the first and second stator end caps, and wherein the position sensor board assembly is within the stator envelope. ### Claim 5 (depends on 4) The power tool of claim 4, wherein the bearing is at least partially within the stator envelope. ### Claim 6 (depends on 4, 6) The power tool of claim 4, the rotor assembly further comprising: a second rotor end cap provided on a second side of the rotor core; and legs that extend from the second rotor end cap, between the stator teeth, to the rotor end cap to seal air gaps at an inner radial end of the stator core between the stator teeth. The power tool of claim 6, further comprising: a gear case mounted to the second rotor end cap by fasteners; a second bearing provided in a second bearing holder of the second rotor end cap, wherein the second bearing couples the second rotor end cap to the output shaft, and wherein the second bearing is at least partially within the stator envelope. ### Claim 8 (depends on 1) The power tool of claim 1, the rotor assembly further comprising: a connector portion providing a pathway that routes a connection between the position sensor board assembly and a sensor terminal block, wherein the pathway extends from the channel, between adjacent coils of the stator assembly, to the sensor terminal block. ### Claim 9 A brushless direct current motor, comprising: a stator assembly including a stator core having stator laminations with an annular portion and inwardly extending stator teeth, a rotor assembly including: a rotor core having rotor laminations and defining a central aperture that receives an output shaft; and a rotor end cap on a first side of the rotor core having a bearing holder and defining a channel, wherein the channel is open on a side of the rotor end cap facing the rotor core, a bearing provided in the bearing holder that couples the rotor end cap to the output shaft, and a position sensor board assembly provided in the channel of the rotor end cap and configured to provide position information of the rotor core to a motor controller. ### Claim 10 (depends on 9) The brushless direct current motor of claim 9, wherein the channel is annular and has a diameter that is less than an inner diameter of the stator assembly. ### Claim 11 (depends on 9) The brushless direct current motor of claim 9, wherein the position sensor board assembly includes a printed circuit board that is annular. ### Claim 12 (depends on 9) The brushless direct current motor of claim 9, wherein the stator assembly includes a first stator end cap and a second stator end cap and the stator laminations are provided between the first and second stator end caps, and wherein the stator assembly defines a stator envelope in an axial direction extending between axial ends of the first and second stator end caps, and wherein the position sensor board assembly is within the stator envelope. ### Claim 13 (depends on 12) The brushless direct current motor of claim 12, wherein the bearing is at least partially within the stator envelope. ### Claim 14 (depends on 12) The brushless direct current motor of claim 12, the rotor assembly further comprising: a second rotor end cap provided on a second side of the rotor core; and legs that extend from the second rotor end cap, between the stator teeth, to the rotor end cap to seal air gaps at an inner radial end of the stator core between the stator teeth. ### Claim 15 (depends on 9) The brushless direct current motor of claim 9, the rotor assembly further comprising: a connector portion providing a pathway that routes a connection between the position sensor board assembly and a sensor terminal block, wherein the pathway extends from the channel, between adjacent coils of the stator assembly, to the sensor terminal block. ### Claim 16 A power tool, comprising: a housing; a controller within the housing; and a brushless motor within the housing and controlled by the controller, the brushless motor including: a stator assembly including a stator core having stator laminations with an annular portion and inwardly extending stator teeth, wherein the stator assembly defines a stator envelope in an axial direction extending between axial ends of stator end caps of the stator assembly, a rotor assembly including: a rotor core having rotor laminations and defining a central aperture that extends in the axial direction and that receives an output shaft, a front rotor end cap provided on a first side of the rotor core, and a rear rotor end cap provided on a second side of the rotor core, and a position sensor board assembly including position sensors and configured to provide position information of the rotor core to the controller, wherein the rotor assembly and the position sensor board assembly are provided at least partially within the stator envelope. ### Claim 17 (depends on 16) The power tool of claim 16, wherein the front rotor end cap has a front bearing holder, and the rear rotor end cap has a rear bearing holder, and wherein the brushless motor further comprises: a front bearing coupling the output shaft to the front rotor end cap, and a rear bearing coupling the output shaft to the rear rotor end cap, and wherein the front bearing and the rear bearing are provided at least partially within the stator envelope. ### Claim 18 (depends on 16) The power tool of claim 16, wherein the rear rotor end cap defines a channel and has a diameter that is less than an inner diameter of the stator assembly, and the channel is open on a side of the rear rotor end cap facing the rotor core and the position sensor board assembly is provided in the channel. ### Claim 19 (depends on 18) The power tool of claim 18, wherein the rear rotor end cap further comprises: a connector portion providing a pathway that routes a connection between the position sensor board assembly and a sensor terminal block, wherein the pathway extends from the channel, between adjacent coils of the stator assembly, to the sensor terminal block. ### Claim 20 (depends on 16) The power tool of claim 16, wherein the position sensor board assembly includes an annular board portion and legs extending radially outward from the annular board portion, and wherein at least one leg of the legs of the position sensor board assembly extends through a gap between adjacent stator end cap teeth of a first stator end cap of the stator end caps.