# US 2014/0197715 A1 · Electric motor with improved flux path and power density > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0197715 A1 - Document ID: US20140197715A1 - Status: Published application - Kind: A1 - Application number: 13/741,900 - Filed: 2013-01-15 - Published: 2014-07-17 - Earliest claimed: 2013-01-15 - Inventors: ROOPNARINE (one name) - Web page: https://patentgrep.com/patent/US20140197715A1 ## CPC - H02K 9/02: by ambient air flowing through the machine - H02K 1/148: {Sectional cores (H02K1/141 takes precedence)} - H02K 19/103: {Motors having windings on the stator and a variable reluctance soft-iron rotor without windings} - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) ## Abstract An improved configuration for an electric motor has an inner rotor and an outer stator wherein each stator coil is arranged radially outwardly of its respective stator pole and configured to create a magnetic flux path forming a closed magnetic circuit that flows in directions parallel to the longitudinal axis of the motor, rather than circumferentially about the longitudinal axis of the motor. The magnetic flux created by the stator coil is directed from the stator pole, across the air gap to a corresponding rotor pole, and back to the stator pole to form a closed magnetic circuit path. All stator poles are therefore magnetically isolated from each other. ## Claims ### Claim 1 An improved configuration for an electric motor comprising: an inner rotor rotatable on a longitudinal axis of the motor and provided with a circumferential array of rotor poles facing radially outwardly, an outer stator provided with a circumferential array of stator poles excitable by respective stator coils facing radially inwardly toward corresponding rotor poles separated by a thin radial air gap, wherein each stator coil is arranged radially outwardly of its respective stator pole and configured to create a magnetic flux path forming a closed magnetic circuit that flows in directions parallel to the longitudinal axis of the motor, rather than circumferentially about the longitudinal axis of the motor. ### Claim 2 (depends on 1) An improved configuration for an electric motor according to claim 1, wherein each stator segment or lamination stack has a coil of windings wound in a direction transverse to the longitudinal axis of the motor. ### Claim 3 (depends on 2) An improved configuration for an electric motor according to claim 2, wherein the magnetic flux path flows from the stator pole on one end of the pole armature, across the radial air gap a first time, through a rotor pole, across the radial air gap a second time, and back to the stator pole on the opposite end of the pole armature to form a closed magnetic flux path. ### Claim 4 (depends on 1) An improved configuration for an electric motor according to claim 1, formed in an enclosed configuration having a forward end cap, rear end cap, and housing containing stator assembly with a rotor assembly. ### Claim 5 (depends on 1) An improved configuration for an electric motor according to claim 1, formed in an open-frame configuration in which the stator coils are exposed to enable convection cooling or ventilation and access to the stator coil windings for replacement or repair without disassembling the entire motor. ### Claim 6 (depends on 1) An improved configuration for an electric motor according to claim 1, wherein said rotor is formed as a rotor assembly having rotor pole pieces each formed by a lamination stack of rotor laminations with pole faces on two ends of its length that is held by pole holders on opposite sides of a longitudinal slot formed in the rotor assembly. ### Claim 7 (depends on 1) An improved configuration for an electric motor according to claim 1, wherein said rotor is formed as a rotor assembly having a rotor housing formed with enclosed slots for insertion of magnetic material for respective rotor pole pieces. ### Claim 8 (depends on 1) An improved configuration for an electric motor according to claim 1, wherein stator poles are formed on each stator segment or lamination stack with multiple separate segments of stator coil windings. ### Claim 9 (depends on 8) An improved configuration for an electric motor according to claim 8, wherein stator poles are formed with two separate segments of stator coil windings. ### Claim 10 (depends on 9) An improved configuration for an electric motor according to claim 9, wherein said rotor is formed in two distinct half-sections in which a first half-section has a number ‘n’ of rotor poles, and a second half-section also has a number ‘n’ of rotor poles that are mechanically offset from the poles of the first half-section by an angle ‘a’ that is 360 degrees divided by twice the number ‘n’ of rotor poles. ### Claim 11 (depends on 1) An improved configuration for an electric motor according to claim 1, wherein each rotor pole is comprised of three sections wherein two of the sections on opposite ends of the rotor pole from each other are magnetic and a third section in between the two is non-magnetic. ### Claim 12 (depends on 1) An improved configuration for an electric motor according to claim 1, wherein each rotor pole is comprised of three sections wherein two of the sections on opposite ends of the rotor pole from each other are magnetic and a third section in between the two is made of Somaloy™ alloy. ### Claim 13 (depends on 1) An improved configuration for an electric motor according to claim 1, wherein said stator is formed as a stator assembly comprised of lamination stacks with respective integral stator poles manufactured from sheets of silicon or electrical steel or soft magnetic alloy and joined together. ### Claim 14 (depends on 1) An improved configuration for an electric motor according to claim 1, wherein said stator is comprised of lamination stacks with integral poles that are each attached to a non-magnetic stator pole holder that hold the lamination stack onto respective mounting parts of a stator holder. ### Claim 15 (depends on 14) An improved configuration for an electric motor according to claim 14, wherein each pole holder is comprised of a lamination stack holder and two end caps, and a fastener is attached to each end cap to clamp the lamination stack in place on the stator holder. ### Claim 16 (depends on 1) An improved configuration for an electric motor according to claim 1, wherein said stator is comprised of a number of lamination stacks with integral poles that are clamped and fastened at each end by fasteners onto locating flats that are integral parts of a stator pole holder, wherein each locating flat forms a slot that will act to constrain the respective lamination stack from rotational movement. ### Claim 17 (depends on 1) An improved configuration for an electric motor according to claim 1, wherein said stator is comprised of a number of lamination stacks with integral poles that are clamped and fastened at each end by fasteners onto locating flats that are integral parts of respective forward end and rear end caps, wherein each locating flat forms a slot that will act to constrain the respective lamination stack from rotational movement. ### Claim 18 (depends on 1) An improved configuration for an electric motor according to claim 1, wherein said stator is comprised of a number of lamination stacks with integral poles that are inserted into, clamped and fastened at each end by fasteners onto the locating flats that are integral parts of respective forward end and rear end caps, wherein slots formed on both the forward end cap and the rear end cap act to constrain the respective lamination stacks to prevent rotational movement. ### Claim 19 (depends on 1) An improved configuration for an electric motor according to claim 1, wherein said stator is comprised of a number of lamination stacks with integral poles that are supported by overhanging ends on respective stator holder flanges on each end, wherein the overhanging ends of the lamination stacks are radially located by slots formed in the stator holder flanges to prevent rotational movement. ### Claim 20 (depends on 1) An improved configuration for an electric motor according to claim 1, wherein said stator is comprised of a number of lamination stacks with integral poles at opposite ends thereof that are supported on locating surfaces on respective stator holder flanges, and are radially located by and keyed to slots formed in the stator holder flanges to prevent rotational movement.