# US 12,603,534 B2 · Electric machine including field coil separators having an integrated coolant flow path > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,603,534 B2 - Document ID: US12603534B2 - Status: Granted - Kind: B2 - Application number: 18/536,528 - Filed: 2023-12-12 - Published: 2025-06-12 - Granted: 2026-04-14 - Earliest claimed: 2023-12-12 - Assignees: BorgWarner Inc. - Applicants: BorgWarner Inc. - Inventors: Kirk Neet; Joshua B. Lahrman - Web page: https://patentgrep.com/patent/US12603534B2 ## CPC - H02K 3/24: with channels or ducts for cooling medium between the conductors - H02K 1/26: Rotor cores with slots for windings - H02K 1/32: with channels or ducts for flow of cooling medium - H02K 9/19: for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) ## Abstract A rotor for an electric machine includes a shaft. A plurality of rotor laminations is mounted to the shaft. The plurality of rotor laminations includes a plurality of rotor teeth. A plurality of field coils is disposed about corresponding ones of the plurality of rotor teeth. A plurality of field coil separators extend axially along the rotor between adjacent ones of the plurality of field coils. Each of the plurality of field coil separators includes a coolant circulation system. The coolant circulation system includes a plurality of external coolant flow paths. Each of the plurality of field coil separators includes a resilient frame and an outer shell over molded onto the resilient frame, the outer shell including an outer surface. ## Claims ### Claim 1 A rotor for an electric machine, the rotor comprising: a shaft including an outer surface section, an inner surface section defining a flow path, and an opening defining a passage extending from the flow path through the outer surface section, the shaft defining an axis of rotation of the rotor; a plurality of rotor laminations mounted to the outer surface section, the plurality of rotor laminations including an inner surface portion disposed on the shaft, an outer surface portion, and a plurality of rotor teeth, the plurality of rotor laminations include a plurality of coolant passages extending between the inner surface portion and the outer surface portion; a plurality of field coils disposed about corresponding ones of the plurality of rotor teeth, the plurality of coolant passages extending axially along the plurality of rotor laminations between adjacent ones of the plurality of field coils; and a plurality of field coil separators extending axially along the rotor between adjacent ones of the plurality of field coils, each of the plurality of field coil separators including a coolant circulation system, the coolant circulation system including a plurality of external coolant flow paths, wherein each of the plurality of field coil separators includes a resilient frame and an outer shell over molded onto the resilient frame, the outer shell including an outer surface. ### Claim 2 (depends on 1) The rotor according to claim 1, the resilient frame includes a base element and a first spring member and the plurality of field coil separators are configured to be loaded into the plurality of coolant passages between adjacent ones of the plurality of field coils by first compressing the first spring member and then releasing the first spring member. ### Claim 3 (depends on 2) The rotor according to claim 2, wherein each of the plurality of field coil separators includes a second spring member. ### Claim 4 (depends on 3) The rotor according to claim 3, the first spring member is configured to engage one of the plurality of field coils and the second spring member configured to engage an adjacent one of the plurality of field coils. ### Claim 5 (depends on 4) The rotor according to claim 4, wherein the base element extends substantially along a radius of the rotor, the first spring member extends from the base element at a first angle and the second spring member extends from the base element at a second angle. ### Claim 6 (depends on 5) The rotor according to claim 5, wherein the base element includes a first outer shell member having a first outer surface, the first spring member includes a second outer shell member having a second outer surface, and the second spring member includes a third outer shell member having a third outer surface. ### Claim 7 (depends on 6) The rotor according to claim 6, wherein the second outer shell member includes a first inner surface section and the third outer shell member includes a second inner surface section, the first inner surface section including a first semi-circular recess and the second inner surface section including a second semi-circular recess, the first semi-circular recess and the second semi-circular recess forming a generally cylindrical passage. ### Claim 8 (depends on 7) The rotor according to claim 7, further comprising: a mechanical fastener extending through the generally cylindrical passage substantially parallel to an axis of rotation of the rotor, the mechanical fastener preventing inward deflection of the first spring member and the second spring member. ### Claim 9 (depends on 6) The rotor according to claim 6, wherein each of the first outer surface includes a plurality of coolant guide elements that define the plurality of external coolant flow paths that direct coolant from the base element, the first spring member, and the second spring member. ### Claim 10 (depends on 9) The rotor according to claim 9, wherein at least one internal coolant return passage includes a first coolant return conduit arranged in the second outer shell member and a second coolant return conduit arranged in the third outer shell member, the first coolant return conduit and the second coolant return conduit extending substantially parallel to the axis of rotation of the rotor. ### Claim 11 (depends on 10) The rotor according to claim 10, wherein the second outer shell member includes a first plurality of passages extending between the second outer surface and the first coolant return conduit and the third outer shell member includes a second plurality of passages extending between the third outer surface and the second coolant return conduit. ### Claim 12 (depends on 7) The rotor according to claim 7, wherein a plurality of cooling guide elements engage adjacent ones of the plurality of field coils. ### Claim 13 An electric machine comprising: a housing including an interior; a stator arranged in the interior and fixedly connected to the housing, the stator including a stator core, and a plurality of stator windings supported by the stator core, the plurality of stator windings having a first end turn and a second end turn, the first end turn being axially spaced from the second end turn by the stator core; a rotor arranged in the interior and rotatably supported within the stator, the rotor comprising: a shaft including an outer surface section, an inner surface section defining a flow path, and an opening defining a passage extending from the flow path through the outer surface section, the shaft defining an axis of rotation of the rotor; a plurality of rotor laminations mounted to the outer surface section, the plurality of rotor laminations including an inner surface portion disposed on the shaft, an outer surface portion, and a plurality of rotor teeth, the plurality of rotor laminations include a plurality of coolant passages extending between the inner surface portion and the outer surface portion; a plurality of field coils disposed about corresponding ones of the plurality of rotor teeth, the plurality of coolant passages extending axially along the plurality of rotor laminations between adjacent ones of the plurality of field coils; and a plurality of field coil separators extending axially along the rotor between adjacent ones of the plurality of field coils, wherein each of the plurality of field coil separators includes a resilient frame and an outer shell over molded onto the resilient frame, the outer shell including an outer surface, wherein the resilient frame includes a base element, a first spring member configured to engage one of the plurality of field coils and a second spring member configured to engage an adjacent one of the plurality of field coils. ### Claim 14 (depends on 13) An electric machine according to claim 13, wherein the plurality of rotor laminations include a first axial end and a second axial end, the first axial end being spaced from the second axial end along the axis of rotation, the first axial end supporting a first balance ring including a first plurality of outlet openings that direct coolant passing from select ones of the plurality of field coil separators onto the first end turn and the second axial end supporting a second balance ring including a second plurality of outlet openings that direct coolant passing from the select ones of the plurality of field coil separators onto the second end turn. ### Claim 15 (depends on 14) The electric machine according to claim 14, each of the plurality of field coil separators including a coolant circulation system, the coolant circulation system including a plurality of external coolant flow paths and at least one internal coolant return passage. ### Claim 16 (depends on 15) The electric machine according to claim 15, wherein the base element extends substantially along a radius of the rotor, the first spring member extends from the base element at a first angle and the second spring member extends from the base element at a second angle. ### Claim 17 (depends on 16) The electric machine according to claim 16, wherein the base element includes a first outer shell member having a first outer surface, the first spring member includes a second outer shell member having a second outer surface, and the second spring member includes a third outer shell member having a third outer surface. ### Claim 18 (depends on 17) The electric machine according to claim 17, wherein the second outer shell member includes a first inner surface section and the third outer shell member includes a second inner surface section, the first inner surface section including a first semi-circular recess and the second inner surface section including a second semi-circular recess, the first semi-circular recess and the second semi-circular recess forming a generally cylindrical passage. ### Claim 19 (depends on 18) The electric machine according to claim 18, further comprising: a mechanical fastener extending through the generally cylindrical passage substantially parallel to an axis of rotation of the rotor, the mechanical fastener preventing inward deflection of the first spring member and the second spring member. ### Claim 20 (depends on 17) The electric machine according to claim 17, wherein each of the first outer surface includes a plurality of coolant guide elements that define the plurality of external coolant flow paths that direct coolant from the base element, the first spring member, and the second spring member. ### Claim 21 (depends on 20) The electric machine according to claim 20, wherein the at least one internal coolant return passage includes a first coolant return conduit arranged in the second outer shell member and a second coolant return conduit arranged in the third outer shell member, the first coolant return conduit and the second coolant return conduit extending substantially parallel to the axis of rotation of the rotor. ### Claim 22 (depends on 21) The electric machine according to claim 21, wherein the second outer shell member includes a first plurality of passages extending between the second outer surface and the first coolant return conduit and the third outer shell member includes a second plurality of passages extending between the third outer surface and the second coolant return conduit.