# US 12,224,627 B2 · Rotor assembly for an electric motor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,224,627 B2 - Document ID: US12224627B2 - Status: Granted - Kind: B2 - Application number: 17/867,989 - Filed: 2022-07-19 - Published: 2024-01-25 - Granted: 2025-02-11 - Earliest claimed: 2022-07-19 - Assignees: BorgWarner Inc. - Applicants: BorgWarner Inc. - Inventors: Calahan B. Campton; Eric Bourniche; James Bourn - Web page: https://patentgrep.com/patent/US12224627B2 ## CPC - H02K 1/32: with channels or ducts for flow of cooling medium - H02K 7/116: with gears - H02K 9/193: with provision for replenishing the cooling medium; with means for preventing leakage of the cooling medium - H02K 2213/03: Machines characterised by numerical values, ranges, mathematical expressions or similar information - 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 assembly includes a shaft defining a lubricant inlet channel for receiving a lubricant and a lamination stack. The lamination stack is rotatably coupled to the shaft, extends between first and second lamination stack ends, and defines a lubricant cooling channel in fluid communication with the lubricant inlet channel. The rotor assembly also includes a first end cap adjacent to the first lamination stack end and a second end cap adjacent to the second lamination stack end. One of the first end cap and the second end cap defines an end cap inlet at a first radial distance from the shaft, a lubricant outlet channel defined to extend at least partially radially inward toward the shaft, and an end cap outlet at a second radial distance from the shaft which is less than the first radial distance for expelling the lubricant. ## Claims ### Claim 1 A rotor assembly for an electric motor, said rotor assembly comprising: a shaft extending along and rotatable about an axis, with said shaft defining a lubricant inlet channel for receiving a lubricant; a lamination stack rotatably coupled to said shaft and extending along said axis between a first lamination stack end and a second lamination stack end, with said lamination stack at least partially defining a lubricant cooling channel between said first lamination stack end and said second lamination stack end and in fluid communication with said lubricant inlet channel; a first end cap adjacent to said first lamination stack end; and a second end cap adjacent to said second lamination stack end; wherein one of said first end cap and said second end cap defines, an end cap inlet at a first radial distance from said shaft for receiving the lubricant from said lubricant cooling channel, a lubricant outlet channel for receiving lubricant from said end cap inlet, with said lubricant outlet channel defined to extend at least partially radially inward toward said shaft, and an end cap outlet at a second radial distance from said shaft which is less than said first radial distance for receiving lubricant from said lubricant outlet channel and for expelling lubricant from said one of said first end cap and said second end cap, wherein said first end cap defines a first end channel for receiving the lubricant from said lubricant inlet channel and for directing the lubricant to said lubricant cooling channel, wherein said second end cap defines a second end channel for receiving the lubricant from said lubricant cooling channel, and wherein said lubricant cooling channel is defined to include a first cooling pass extending between said first end channel and said second end channel and a second cooling pass extending from said second end channel toward said first end cap. ### Claim 2 (depends on 1) The rotor assembly as set forth in claim 1, wherein said one of said first end cap and said second end cap extends a third radial distance from said shaft, and wherein said second radial distance of said end cap outlet is less than half of said third radial distance. ### Claim 3 (depends on 2) The rotor assembly as set forth in claim 2, wherein said second radial distance is less than 20% of said third radial distance. ### Claim 4 (depends on 1) The rotor assembly as set forth in claim 1, wherein said one of said first end cap and said second end cap extends a third radial distance from said shaft, and wherein said first radial distance of said end cap inlet is greater than half of said third radial distance. ### Claim 5 (depends on 1) The rotor assembly as set forth in claim 1, wherein said lubricant cooling channel is at least partially delimited by said shaft. ### Claim 6 (depends on 1) The rotor assembly as set forth in claim 1, wherein said first end channel is defined to extend radially outward relative to said axis and wherein said second end channel is defined to extend radially outward relative to said axis. ### Claim 7 (depends on 1) The rotor assembly as set forth in claim 1, wherein said first end cap further defines a third end channel for receiving the lubricant from said second cooling pass, and wherein said lubricant cooling channel is further defined to include a third cooling pass extending from said third end channel toward said second end cap. ### Claim 8 (depends on 7) The rotor assembly as set forth in claim 7, wherein said third end channel is defined to extend radially outward relative to said axis. ### Claim 9 (depends on 1) The rotor assembly as set forth in claim 1, wherein said first end cap defines said end cap inlet, said lubricant outlet channel, and said end cap outlet. ### Claim 10 (depends on 1) The rotor assembly as set forth in claim 1, wherein said second end cap defines said end cap inlet, said lubricant outlet channel, and said end cap outlet. ### Claim 11 An electric motor system comprising: an electric motor including, a stator extending along an axis and defining a stator interior; and a rotor assembly disposed in said stator interior of said stator, said rotor assembly including, a shaft extending along and rotatable about an axis, with said shaft defining a lubricant inlet channel for receiving a lubricant; a lamination stack rotatably coupled to said shaft and extending along said axis between a first lamination stack end and a second lamination stack end, with said lamination stack defining a lubricant cooling channel between said first lamination stack end and said second lamination stack end and in fluid communication with said lubricant inlet channel; a first end cap adjacent to said first lamination stack end; and a second end cap adjacent to said second lamination stack end; wherein one of said first end cap and said second end cap defines, an end cap inlet at a first radial distance from said shaft for receiving the lubricant from said lubricant cooling channel, a lubricant outlet channel for receiving lubricant from said end cap inlet, with said lubricant outlet channel defined to extend at least partially radially inward toward said shaft, and an end cap outlet at a second radial distance from said shaft which is less than said first radial distance for receiving lubricant from said lubricant outlet channel and for expelling lubricant from said one of said first end cap and said second end cap; a housing disposed about said electric motor; and a pressurized lubricant feed configured to provide lubricant under pressure to said lubricant inlet channel defined by said shaft, wherein said pressurized lubricant feed is defined at least partially by said housing. ### Claim 12 (depends on 11) The electric motor system as set forth in claim 11 further comprising a pump configured to pressurize lubricant and in fluid communication with said pressurized lubricant feed. ### Claim 13 (depends on 11) The electric motor system as set forth in claim 11 further comprising at least one seal disposed between said housing and said shaft adjacent to said pressurized lubricant feed to fluidly seal an inlet interface between said housing and said shaft. ### Claim 14 (depends on 11) The electric motor system as set forth in claim 11 further comprising a return line to receive the lubricant expelled from said one of said first end cap and said second end cap to permit reuse of the pressurized lubricant. ### Claim 15 (depends on 14) The electric motor system as set forth in claim 14 wherein said shaft defines a return channel in fluid communication with said end cap outlet and said return line to direct lubricant from said end cap outlet to said return line. ### Claim 16 (depends on 15) The electric motor system as set forth in claim 15 further comprising at least one seal disposed between said housing and said shaft adjacent to said return line to fluidly seal an outlet interface between said housing and said shaft. ### Claim 17 (depends on 11) An electric drive unit system comprising: said electric motor system as set forth in claim 11, and a gear reduction mechanism coupled to said shaft and configured to modulate torque received from said shaft. ### Claim 18 An electric motor system comprising: an electric motor including, a stator extending along an axis and defining a stator interior; and a rotor assembly disposed in said stator interior of said stator, said rotor assembly including, a shaft extending along and rotatable about an axis, with said shaft defining a lubricant inlet channel for receiving a lubricant; a lamination stack rotatably coupled to said shaft and extending along said axis between a first lamination stack end and a second lamination stack end, with said lamination stack defining a lubricant cooling channel between said first lamination stack end and said second lamination stack end and in fluid communication with said lubricant inlet channel; a first end cap adjacent to said first lamination stack end; and a second end cap adjacent to said second lamination stack end; wherein one of said first end cap and said second end cap defines, an end cap inlet at a first radial distance from said shaft for receiving the lubricant from said lubricant cooling channel, a lubricant outlet channel for receiving lubricant from said end cap inlet, with said lubricant outlet channel defined to extend at least partially radially inward toward said shaft, and an end cap outlet at a second radial distance from said shaft which is less than said first radial distance for receiving lubricant from said lubricant outlet channel and for expelling lubricant from said one of said first end cap and said second end cap; and a return line to receive the lubricant expelled from said one of said first end cap and said second end cap to permit reuse of the pressurized lubricant; wherein said shaft defines a return channel in fluid communication with said end cap outlet and said return line to direct lubricant from said end cap outlet to said return line. ### Claim 19 (depends on 18) The electric motor system as set forth in claim 18, wherein said first end cap defines a first end channel for receiving the lubricant from said lubricant inlet channel and for directing the lubricant to said lubricant cooling channel, wherein said second end cap defines a second end channel for receiving the lubricant from said lubricant cooling channel, and wherein said lubricant cooling channel is defined to include a first cooling pass extending between said first end channel and said second end channel and a second cooling pass extending from said second end channel toward said first end cap. ### Claim 20 (depends on 18) The electric motor system as set forth in claim 18 further comprising a housing disposed about said electric motor and at least one seal disposed between said housing and said shaft adjacent to said return line to fluidly seal an outlet interface between said housing and said shaft.