Rotor cooling with air and oil mixture

Abstract

A rotor assembly includes a rotor having a first rotor end and a second rotor end. The rotor defines a first cooling duct and a second cooling duct. The rotor assembly includes a first impeller coupled to a first rotor end and a second impeller coupled to a second rotor end. The rotor assembly also includes a first oil passage configured to direct oil to the first cooling conduit and a second oil passage configured to direct oil to the second cooling conduit. The first oil passage is fluidly coupled with the first cooling conduit such that oil and air mix within the first cooling conduit during operation of the rotor assembly, and the second oil passage is fluidly coupled with the second cooling conduit such that oil and air mix within the second cooling conduit during operation of the rotor assembly.

Description

Cross - Reference to Related Applications

[0001] This application claims the benefit of priority and all rights of U.S. Provisional Application No. 63 / 625,960, filed on January 27, 2024, which is hereby incorporated by reference in its entirety. Technical Field

[0002] The present invention relates to a rotor assembly, and more particularly to a rotor assembly for an electric motor. Background Art

[0003] Typical electric motors, such as those for vehicles, include a rotor assembly that includes a rotor extending along a rotor axis and rotatable about the rotor axis, a shaft extending along the rotor axis, and a stator coupled to the rotor and disposed about the rotor relative to the rotor axis. For vehicles, as performance and efficiency requirements continue to increase, the demand for electric motors has increased. For example, with higher outputs from electric motors, the desired rotational speed of the shaft has increased, which has increased the need for improved cooling and balancing of the electric motor and particularly the rotor assembly.

[0004] Accordingly, there remains a need for an improved rotor assembly for an electric motor. Summary of the Invention

[0005] A rotor assembly for an electric motor includes a rotor extending along a rotor axis and adapted to be rotatable about the rotor axis. The rotor has a first rotor end and a second rotor end spaced from the first rotor end relative to the rotor axis. The rotor defines a first cooling duct extending from the first rotor end to the second rotor end and a second cooling duct extending from the first rotor end to the second rotor end. The rotor assembly includes a first impeller coupled to the first rotor end. The first impeller defines an inlet opening aligned with the first cooling duct and an outlet opening aligned with the second cooling duct. The rotor assembly further includes a second impeller coupled to the second rotor end such that the rotor is disposed between the first impeller and the second impeller relative to the rotor axis. The second impeller defines an inlet opening aligned with the second cooling duct and the outlet opening of the first impeller and an outlet opening aligned with the first cooling duct and the inlet opening of the first impeller. The rotor assembly further includes a first oil passage configured to direct oil to the first cooling duct adjacent to the first impeller and a second oil passage configured to direct oil to the second cooling duct adjacent to the second impeller. The first oil passage is fluidly coupled to the first cooling duct such that oil and air are mixed within the first cooling duct during operation of the rotor assembly, and the second oil passage is fluidly coupled to the second cooling duct such that oil and air are mixed within the second cooling duct during operation of the rotor assembly. Brief Description of the Drawings

[0006] Other advantages of the present disclosure will be readily appreciated, as they become better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings.

[0007] Figure 1 is a perspective view of an electric machine including a rotor assembly.

[0008] Figure 2 is a perspective view of the electric machine with the housing of the electric machine removed.

[0009] Figure 3 is a front view of the electric machine.

[0010] Figure 4 is an exploded view of the rotor assembly, wherein the rotor assembly includes a rotor extending along a rotor axis, a first impeller, and a second impeller.

[0011] Figure 5 is a perspective view of the first impeller and the second impeller, which illustrates an air flow through a cooling duct defined by the rotor.

[0012] Figure 6 is a front view of the first impeller.

[0013] Figure 7 is a rear view of the first impeller.

[0014] Figure 8 is a rear view of the second impeller.

[0015] Figure 9 is a front view of the second impeller.

[0016] Figure 10 is a perspective view of another embodiment of the first impeller and the second impeller.

[0017] Figure 11 is Figure 10 a front view of the first impeller of

[0018] Figure 12 is Figure 10 a rear view of the first impeller of

[0019] Figure 13 is Figure 10 a rear view of the second impeller of

[0020] Figure 14 is Figure 10 a front view of the second impeller of

[0021] Figure 15 is Figure 10 a perspective view of the first impeller of

[0022] Figure 16 is Figure 10Perspective view of the second impeller.

[0023] Figure 17 is Figure 8 Rear view of the second impeller.

[0024] Figure 18 is Figure 13 Rear view of the second impeller.

[0025] Figure 19 is a cross-sectional view of the rotor assembly, wherein the rotor assembly includes a first oil passage configured to direct oil to a first cooling duct adjacent to the first impeller and a second oil passage configured to direct oil to the second cooling duct adjacent to the second impeller.

[0026] Figure 20 is Figure 19 Cross-sectional view of another embodiment of the rotor assembly. Detailed Description

[0027] Referring to the accompanying drawings, in which like reference numerals indicate like parts throughout the several views, a rotor assembly 50 for an electric machine 52 is shown in Figure 1 . The electric machine 52 may include a housing 54 that defines an interior of the housing.

[0028] Referring to Figures 2 - 4 , the rotor assembly 50 includes a rotor 58 that extends along a rotor axis RA and is adapted to rotate about the rotor axis RA. The rotor 58 has a first rotor end 60 and a second rotor end 62 that is spaced from the first rotor end 60 relative to the rotor axis RA. The rotor 58 may be composed of a laminated stack.

[0029] The electric machine 52 includes: a rotor assembly 50; a shaft 64 that extends along the rotor axis RA, wherein the rotor 58 defines a rotor interior 66, and the shaft 64 is disposed within the rotor interior 66 and coupled to the rotor 58; and a stator 68 that is coupled to the rotor 58 and disposed about the rotor 58 relative to the rotor axis RA. The shaft 64 may be integral with the rotor 58 (i.e., a single piece), or the shaft 64 may be a separate component from the rotor 58 (i.e., two or more components).

[0030] The rotor assembly 50 and thus the electric machine 52 can be used in any suitable application, such as in vehicles, traction motors, turbomachinery, ships, trains, etc. The electric machine 52 can be used in any traction and / or electric power generation. In other words, the electric machine 52 can be configured as a motor and / or a generator. The rotor 58 and thus the shaft 64 can be configured to rotate at greater than 18000 RPM, greater than 19000 RPM, greater than 20000 RPM, greater than 21000 RPM, greater than 22000 RPM, greater than 23000 RPM, greater than 24000 RPM, greater than 25000 RPM, greater than 26000 RPM, and / or greater than 27000 RPM during operation of the electric machine 52.

[0031] The rotor 58 defines a first cooling duct 70 extending from a first rotor end 60 to a second rotor end 62 and a second cooling duct 72 extending from the first rotor end 60 to the second rotor end 62.

[0032] The rotor assembly further includes a first impeller 74 coupled to the first rotor end 60. The first impeller 74 defines an inlet opening 76 aligned with the first cooling duct 70 and an outlet opening 78 aligned with the second cooling duct 72. The rotor assembly 50 further includes a second impeller 80 coupled to the second rotor end 62 such that the rotor 58 is disposed between the first impeller 74 and the second impeller 80 relative to the rotor axis RA. The second impeller 80 defines an inlet opening 82 aligned with the second cooling duct 72 and the outlet opening 78 of the first impeller 74 and an outlet opening 84 aligned with the first cooling duct 70 and the inlet opening 76 of the first impeller 74.

[0033] With particular reference Figures 6 - 9 , the inlet opening 76 of the first impeller 74 has an inlet geometric center 86, and the inlet geometric center 86 defines a first inlet radius R1 between the inlet geometric center 86 of the inlet opening 76 of the first impeller 74 and the rotor axis RA. Similarly, the outlet opening 84 of the second impeller 80 has an outlet geometric center 88, and the outlet geometric center 88 defines a first outlet radius R2 between the outlet geometric center 88 of the outlet opening 84 of the second impeller 80 and the rotor axis RA. The inlet opening 82 of the second impeller 80 has an inlet geometric center 90, where the inlet geometric center 90 of the inlet opening 82 of the second impeller 80 defines a first inlet radius R3 between the inlet geometric center 90 of the inlet opening 82 of the second impeller 80 and the rotor axis RA. The outlet opening 78 of the first impeller 74 has an outlet geometric center 92, where the outlet geometric center 92 of the outlet opening 78 of the first impeller 74 defines a first outlet radius R4 between the outlet geometric center 92 of the outlet opening 78 of the first impeller 74 and the rotor axis RA.

[0034] A first outlet radius R2 defined between an outlet geometric center 88 of an outlet opening 84 of a second impeller 80 and a rotor axis RA is greater than a first inlet radius R1 defined between an inlet geometric center 86 of an inlet opening 76 of a first impeller 74 and the rotor axis RA, such that the first impeller 74 and the second impeller 80 are adapted to direct an air flow in a first direction through a first cooling duct 70 from a first rotor end 60 to a second rotor end 62 when the rotor 58, the first impeller 74, and the second impeller 80 rotate about the rotor axis RA. Similarly, a first outlet radius R4 defined between an outlet geometric center 92 of an outlet opening 78 of the first impeller 74 and the rotor axis RA is greater than a first inlet radius R3 defined between an inlet geometric center 90 of an inlet opening 82 of the second impeller 80 and the rotor axis RA, such that the first impeller 74 and the second impeller 80 are adapted to direct an air flow in a second direction opposite to the first direction through a second cooling duct 72 from the second rotor end 62 to the first rotor end 60 when the rotor 58, the first impeller 74, and the second impeller 80 rotate about the rotor axis RA.

[0035] There are provided several advantages by having (1) a first impeller 74 defining an inlet opening 76 aligned with a first cooling duct 70 and defining an outlet opening 78 aligned with a second cooling duct 72, (2) a second impeller 80 defining an inlet opening 82 aligned with the second cooling duct 72 and the outlet opening 78 of the first impeller 74 and defining an outlet opening 84 aligned with the first cooling duct 70 and the inlet opening 76 of the first impeller 74, and (3) a first outlet radius R2 defined between an outlet geometric center 88 of the outlet opening 84 of the second impeller 80 and a rotor axis RA being greater than a first inlet radius R1 defined between an inlet geometric center 86 of the inlet opening 76 of the first impeller 74 and the rotor axis RA, and a first outlet radius R4 defined between an outlet geometric center 92 of the outlet opening 78 of the first impeller 74 and the rotor axis RA being greater than a first inlet radius R3 defined between an inlet geometric center 90 of the inlet opening 82 of the second impeller 80 and the rotor axis RA. First, as described above, this allows air flows through the first cooling duct 70 and the second cooling duct 72 to flow in opposite directions to each other, which further cools the rotor 58 during operation of the electric machine 52. Second, the inlet opening 76 defined by the first impeller 74 and the outlet opening 84 defined by the second impeller 80 act as nozzles by sucking air from the inlet opening 76 to the outlet opening 84 and forcing air from the inlet opening 76 to the outlet opening 84, and the inlet opening 82 defined by the second impeller 80 and the outlet opening 78 defined by the first impeller 74 act as nozzles by sucking air from the inlet opening 82 to the outlet opening 78 and forcing air from the inlet opening 82 to the outlet opening 78. To further act as nozzles, the cross-sectional area of the inlet opening 76 defined by the first impeller 74 relative to the rotor axis RA may be greater than the cross-sectional area of the outlet opening 84 defined by the second impeller 80. Third, the first impeller 74 and the second impeller 80 may also be configured as balance disks such that when the shaft 64 rotates about the rotor axis RA during operation of the electric machine 52, material may be subtracted from or added to the first impeller 74 and / or the second impeller 80 in order to balance the rotor 58 relative to the shaft 64.

[0036] Typically, the first impeller 74, the second impeller 80, and the rotor 58 are adapted to rotate consistently about the rotor axis RA during operation of the electric machine 52. The first rotor end 60 has a first rotor face 94, and the second rotor end 62 has a second rotor face 96 facing opposite the first rotor face 94 relative to the rotor axis RA. The first impeller 74 may be engaged with the first rotor face 94, and the second impeller 80 may be engaged with the second rotor face 96. In one embodiment, the first impeller 74 is directly engaged with the first rotor face 94, and the second impeller 80 is directly engaged with the second rotor face 96.

[0037] As Figure 4As shown, the rotor assembly 50 may include a plurality of magnets 98 disposed in the rotor 58. The rotor 58 can define a plurality of magnet channels 100 adjacent to the magnets 98, and the plurality of magnet channels 100 can be filled with an injection molding material. Alternatively, the plurality of magnet channels 100 can be hollow. Although not shown in the figures, it should be appreciated that, particularly when the plurality of magnet channels 100 are hollow, the first impeller 74 can define a magnet opening configured to align with at least one of the magnet channels 100 among the plurality of magnet channels 100, and the second impeller 80 can define a magnet opening configured to align with at least one of the magnet channels 100 among the plurality of magnet channels 100. Having hollow magnet channels 100 provides additional cooling for the rotor 58.

[0038] Reference Figures 6 - 9 , the first impeller 74 can have a first hub portion 102 and a first impeller arm 104 that extends from the first hub portion 102 and away from the rotor axis RA. When present, the first impeller arm 104 can define an inlet opening 76 of the first impeller 74. The first impeller 74 can also have a second impeller arm 106 that extends from the first hub portion 102 away from the rotor axis RA and defines an outlet opening 78 of the first impeller 74.

[0039] The first hub portion 102 can have an outer first hub surface 108 disposed between the first impeller arm 104 and the second impeller arm 106 of the first impeller 74. The outer first hub surface 108 defines an outer first hub radius R5 between the outer first hub surface 108 and the rotor axis RA. The first impeller arm 104 and the second impeller arm 106 of the first impeller 74 project away from the outer first hub surface 108 relative to the rotor axis RA.

[0040] The outlet opening 78 of the first impeller 74 can be disposed outside the outer first hub radius R5 relative to the rotor axis RA. The inlet opening 76 of the first impeller 74 can also be disposed outside the outer first hub radius R5 relative to the rotor axis RA.

[0041] The outlet opening 78 of the first impeller 74 can have a curved or angled configuration relative to the rotor axis. In such embodiments, the outlet opening 78 of the first impeller 74 can be curved or angled relative to the rotor axis RA in a clockwise or counterclockwise configuration. Alternatively, the outlet opening 78 of the first impeller 74 can have a straight configuration relative to the rotor axis RA.

[0042] The first impeller 74 may have a first impeller surface 110 facing the rotor 58, and an outlet opening 78 of the first impeller 74 may be defined by the first impeller surface 110 of the first impeller 74. The outlet opening 78 of the first impeller 74 may be partially defined through the first impeller 74. The first impeller 74 also has a second impeller surface 112 opposite to the first impeller surface 110 of the first impeller 74 with respect to the rotor axis RA. The first impeller 74 has a first impeller thickness 114 defined between the first impeller surface 110 and the second impeller surface 112 of the first impeller 74, and the outlet opening 78 of the first impeller 74 has an outlet depth 116 with respect to the rotor axis RA, and the outlet depth 116 is less than the first impeller thickness 114.

[0043] The inlet opening 76 of the first impeller 74 may have a symmetric configuration with respect to the rotor axis RA. For example, the inlet opening 76 of the first impeller 74 may have a semi-circular configuration. The first impeller arm 104 of the first impeller 74 and the second impeller arm 106 of the first impeller 74 may be radially spaced 180 degrees from each other with respect to the rotor axis.

[0044] Similar to the first impeller 74, the second impeller 80 may have a second hub portion 118 and may include: a first impeller arm 120 that extends from the second hub portion 118 and away from the rotor axis RA, defining an inlet opening 82 of the second impeller 80; and a second impeller arm 122 that extends from the second hub portion 118 away from the rotor axis RA, defining an outlet opening 84 of the second impeller 80. The second hub portion 118 has an outer second hub surface 124 disposed between the first impeller arm 120 and the second impeller arm 122 of the second impeller 80. The outer second hub surface 124 defines an outer second hub radius R6 between the outer second hub surface 124 and the rotor axis RA, and the first impeller arm 120 and the second impeller arm 122 of the second impeller 80 project away from the outer second hub surface 124 with respect to the rotor axis RA.

[0045] The outlet opening 84 of the second impeller 80 is disposed outside the outer second hub radius R6 with respect to the rotor axis RA. The inlet opening 82 of the second impeller 80 may also be disposed outside the outer second hub radius R6 with respect to the rotor axis RA. The outlet opening 84 of the second impeller 80 may have a curved or angled configuration with respect to the rotor axis RA and may be curved or angled in a clockwise or counterclockwise configuration with respect to the rotor axis RA. Alternatively, the outlet opening 84 of the second impeller 80 may have a straight configuration with respect to the rotor axis RA.

[0046] The second impeller 80 has a first impeller surface 126 facing the rotor 58, and an outlet opening 84 of the second impeller 80 can be defined by a second impeller surface 128 of the second impeller 80. The outlet opening 84 of the second impeller 80 can be partially defined through the second impeller 80. The second impeller 80 also has a second impeller surface 128 opposite the first impeller surface 126 of the second impeller 80 with respect to the rotor axis RA. The second impeller 80 has a second impeller thickness 130 defined between the first impeller surface 126 and the second impeller surface 128 of the second impeller 80, and the outlet opening 84 of the second impeller 80 has an outlet depth 132 with respect to the rotor axis RA, and the outlet depth 132 can be less than the second impeller thickness 130.

[0047] In one embodiment, the rotor 58 can define a third cooling duct 134 extending from a first rotor end 60 to a second rotor end 62 and a fourth cooling duct 136 extending from the first rotor end 60 to the second rotor end 62. The first impeller 74 can define a second inlet opening 138 aligned with the third cooling duct 134 and a second outlet opening 140 aligned with the fourth cooling duct 136. The second impeller 80 can define a second inlet opening 142 aligned with the fourth cooling duct 136 and the second outlet opening 144 of the first impeller 74, and a second outlet opening 144 aligned with the third cooling duct 134 and the second inlet opening 138 of the first impeller 74.

[0048] The second inlet opening 138 of the first impeller 74 has an inlet geometric center 146, and the inlet geometric center 146 defines a second inlet radius R7 between the inlet geometric center 146 of the second inlet opening 138 of the first impeller 74 and the rotor axis RA. Similarly, the second outlet opening 144 of the second impeller 80 has an outlet geometric center 148, and the outlet geometric center 148 defines a second outlet radius R8 between the outlet geometric center 148 of the second outlet opening 144 of the second impeller 80 and the rotor axis RA. The second inlet opening 142 of the second impeller 80 has an inlet geometric center 150. The inlet geometric center 150 of the second inlet opening 142 of the second impeller 80 and the rotor axis RA define a second inlet radius R9 therebetween. The second outlet opening 140 of the first impeller 74 also defines an outlet geometric center 152, and the outlet geometric center 152 of the second outlet opening of the first impeller 74 defines a second outlet radius R10 between the outlet geometric center 152 of the second outlet opening 140 of the first impeller 74 and the rotor axis RA.

[0049] The second outlet radius R8 defined between the outlet geometric center 148 of the second outlet opening 144 of the second impeller 80 and the rotor axis RA may be greater than the second inlet radius R7 defined between the inlet geometric center 146 of the second inlet opening 138 of the first impeller 74 and the rotor axis RA, such that the first impeller 74 and the second impeller 80 are adapted to direct an air flow in a first direction through the third cooling duct 134 from the first rotor end 60 to the second rotor end 62 when the rotor 58, the first impeller 74, and the second impeller 80 rotate about the rotor axis RA. Similarly, the second outlet radius R10 defined between the outlet geometric center 152 of the second outlet opening 140 of the first impeller 74 and the rotor axis RA may be greater than the second inlet radius R9 defined between the inlet geometric center 150 of the second inlet opening 142 of the second impeller 80 and the rotor axis RA, such that the first impeller 74 and the second impeller 80 are adapted to direct an air flow in a second direction opposite to the first direction through the fourth cooling duct 136 from the second rotor end 62 to the first rotor end 60 when the rotor 58, the first impeller 74, and the second impeller 80 rotate about the rotor axis RA.

[0050] As Figure 4 and Figure 5 shown, the rotor 58 may further define a fifth cooling duct 154 extending from the first rotor end 60 to the second rotor end 62 and a sixth cooling duct 156 extending from the first rotor end 60 to the second rotor end 62. The first impeller 74 may define a third inlet opening 158 aligned with the fifth cooling duct 154 and a third outlet opening 160 aligned with the sixth cooling duct 156. The second impeller 80 may define a third inlet opening 162 aligned with the sixth cooling duct 156 and the third outlet opening 160 of the first impeller 74, and a third outlet opening 164 aligned with the fifth cooling duct 154 and the third inlet opening 158 of the first impeller 74.

[0051] Referring again to Figures 6 - 9, the third inlet opening 158 of the first impeller 74 has an inlet geometric center 166, and the inlet geometric center 166 defines a third inlet radius R11 between the inlet geometric center 166 of the third inlet opening 158 of the first impeller 74 and the rotor axis RA. Similarly, the third outlet opening 164 of the second impeller 80 has an outlet geometric center 168, and the outlet geometric center 168 defines a third outlet radius R12 between the outlet geometric center 168 of the third outlet opening 164 of the second impeller 80 and the rotor axis RA. The third inlet opening 162 of the second impeller 80 has an inlet geometric center 170, where the inlet geometric center 170 of the third inlet opening 162 of the second impeller 80 defines a third inlet radius R13 between the inlet geometric center 170 of the third inlet opening 162 of the second impeller 80 and the rotor axis RA. The third outlet opening 160 of the first impeller 74 has an outlet geometric center 172, where the outlet geometric center 172 of the third outlet opening 160 of the first impeller 74 defines a third outlet radius R14 between the outlet geometric center 172 of the third outlet opening 160 of the first impeller 74 and the rotor axis RA.

[0052] The third outlet radius R12 defined between the outlet geometric center 168 of the third outlet opening 164 of the second impeller 80 and the rotor axis RA can be greater than the third inlet radius R11 defined between the inlet geometric center 166 of the third inlet opening 158 of the first impeller 74 and the rotor axis RA, such that the first impeller 74 and the second impeller 80 are adapted to direct an air flow in a first direction through the fifth cooling duct 154 from the first rotor end 60 to the second rotor end 62 when the rotor 58, the first impeller 74, and the second impeller 80 rotate about the rotor axis RA. Similarly, the third outlet radius R14 defined between the outlet geometric center 172 of the third outlet opening 160 of the first impeller 74 and the rotor axis RA is greater than the third inlet radius R13 defined between the inlet geometric center 170 of the third inlet opening 162 of the second impeller 80 and the rotor axis RA, such that the first impeller 74 and the second impeller 80 are adapted to direct an air flow in a second direction opposite to the first direction through the sixth cooling duct 156 from the second rotor end 62 to the first rotor end 60 when the rotor 58, the first impeller 74, and the second impeller 80 rotate about the rotor axis.

[0053] In one embodiment, a first inlet opening 76 of the first impeller 74, a first outlet opening 78 of the first impeller 74, a second inlet opening 138 of the first impeller 74, a second outlet opening of the first impeller 74, a third inlet opening 158 of the first impeller 74, and a third outlet opening 160 of the first impeller 74 are equally radially spaced from each other with respect to and around a rotor axis RA. Similarly, a first inlet opening 82 of the second impeller 80, a first outlet opening 84 of the second impeller 80, a second inlet opening 142 of the second impeller 80, a second outlet opening 144 of the second impeller 80, a third inlet opening 162 of the second impeller 80, and a third outlet opening 164 of the second impeller 80 can be equally radially spaced from each other with respect to and around the rotor axis RA.

[0054] The first impeller 74 may include a third impeller arm 174 extending from the first hub portion 102 and away from the rotor axis RA, wherein the third impeller arm 174 of the first impeller 74 defines the second inlet opening 138 of the first impeller 74. The first impeller 74 may include a fourth impeller arm 176 extending from the first hub portion 102 away from the rotor axis RA, wherein the fourth impeller arm 176 of the first impeller 74 defines the second outlet opening 140 of the first impeller 74. The first impeller 74 may include a fifth impeller arm 178 extending from the first hub portion 102 away from the rotor axis RA, wherein the fifth impeller arm 178 of the first impeller 74 defines the third inlet opening 158 of the first impeller 74. The first impeller 74 may include a sixth impeller arm 180 extending from the first hub portion 102 away from the rotor axis RA, wherein the sixth impeller arm 180 defines the third outlet opening 160 of the first impeller 74. Similarly, the second impeller 80 may include a third impeller arm 182 extending from the second hub portion 118 and away from the rotor axis RA, wherein the third impeller arm 182 of the second impeller 80 defines the second inlet opening 142 of the second impeller 80. The second impeller 80 may include a fourth impeller arm 184 extending from the second hub portion 118 away from the rotor axis RA, wherein the fourth impeller arm 184 of the second impeller 80 defines the second outlet opening 144 of the second impeller 80. The second impeller 80 may include a fifth impeller arm 186 extending from the second hub portion 118 away from the rotor axis RA, wherein the fifth impeller arm 186 of the second impeller 80 defines the third inlet opening 162 of the second impeller 80. The second impeller 80 may include a sixth impeller arm 188 extending from the second hub portion 118 away from the rotor axis RA, wherein the sixth impeller arm 188 defines the third outlet opening 164 of the second impeller 80.

[0055] In another embodiment, as Figures 10 - 16As shown in, the first impeller 74 can be capable of having a first hub portion 102 and may include a first impeller arm 104 extending from the first hub portion 102 and away from the rotor axis RA, wherein the first impeller arm 104 defines both an inlet opening 76 of the first impeller 74 and an outlet opening 78 of the first impeller 74. Similarly, the second impeller 80 may have a second hub portion and may include a first impeller arm 120 of the second impeller 80 extending from the second hub portion 118 and away from the rotor axis RA, wherein the first impeller arm 120 of the second impeller 80 defines both an outlet opening 84 of the second impeller 80 and an inlet opening 82 of the second impeller 80.

[0056] As described above, the rotor 58 may define a third cooling duct 134 and a fourth cooling duct 136, wherein the first impeller 74 defines a second inlet opening 138 aligned with the third cooling duct 134 and a second outlet opening 140 aligned with the fourth cooling duct 136. The second impeller 80 may define a second inlet opening 142 aligned with the fourth cooling duct 136 and the second outlet opening 140 of the first impeller 74, and the second impeller 80 may define a second outlet opening 144 aligned with the third cooling duct 134 and the second inlet opening 138 of the first impeller 74.

[0057] In Figures 10 - 16 the embodiment shown, the second inlet opening 138 of the first impeller 74 has an inlet geometric center 146, and the inlet geometric center 146 defines a second inlet radius R7 between the inlet geometric center 146 of the second inlet opening 138 of the first impeller 74 and the rotor axis RA. Similarly, the second outlet opening 144 of the second impeller 80 has an outlet geometric center 148, and the outlet geometric center 148 defines a second outlet radius R8 between the outlet geometric center 148 of the second outlet opening 144 of the second impeller 80 and the rotor axis RA. The second inlet opening 142 of the second impeller 80 has an inlet geometric center 150, wherein the inlet geometric center 150 of the second inlet opening 142 of the second impeller 80 defines a second inlet radius R9 between the inlet geometric center 150 of the second inlet opening 142 of the second impeller 80 and the rotor axis RA. The second outlet opening 140 of the first impeller 74 has an outlet geometric center 152, and the outlet geometric center 152 of the second outlet opening 140 of the first impeller 74 defines a second outlet radius R10 between the outlet geometric center 152 of the second outlet opening 140 of the first impeller 74 and the rotor axis RA.

[0058] The second outlet radius R8 defined between the outlet geometric center 148 of the second outlet opening 144 of the second impeller 80 and the rotor axis RA may be greater than the second inlet radius R7 defined between the inlet geometric center 146 of the second inlet opening 138 of the first impeller 74 and the rotor axis RA, such that the first impeller 74 and the second impeller 80 are adapted to direct an air flow in a first direction through the third cooling duct 134 from the first rotor end 60 to the second rotor end 62 when the rotor 58, the first impeller 74, and the second impeller 80 rotate about the rotor axis RA. Similarly, the second outlet radius R10 defined between the outlet geometric center 152 of the second outlet opening 140 of the first impeller 74 and the rotor axis RA may be greater than the second inlet radius R9 defined between the inlet geometric center 150 of the second inlet opening 142 of the second impeller 80 and the rotor axis RA, such that the first impeller 74 and the second impeller 80 are adapted to direct an air flow in a second direction opposite to the first direction through the fourth cooling duct 136 from the second rotor end 62 to the first rotor end 60 when the rotor 58, the first impeller 74, and the second impeller 80 rotate about the rotor axis RA.

[0059] The first impeller 74 may include a second impeller arm 106 extending from the first hub portion 102 and away from the rotor axis RA, wherein the second impeller arm 106 defines the second inlet opening 138 of the first impeller 74 and the second outlet opening 140 of the first impeller 74. Similarly, the second impeller 80 may include a second impeller arm 122 extending from the second hub portion 118 and away from the rotor axis RA, wherein the second impeller arm 122 defines the second inlet opening 142 of the second impeller 80 and the second outlet opening 144 of the second impeller 80.

[0060] Figure 10 The rotor 58 shown (which may be the same as the rotor 58 shown Figures 2 - 4 also may define a fifth cooling duct 154 extending from the first rotor end 60 to the second rotor end 62 and a sixth cooling duct 156 extending from the first rotor end 60 to the second rotor end 62. Referring again to Figures 10 - 16 , the first impeller 74 may define a third inlet opening 158 aligned with the fifth cooling duct 154 and a third outlet opening 160 aligned with the sixth cooling duct 156. The second impeller 80 may define a third inlet opening 162 aligned with the sixth cooling duct 156 and the third outlet opening 160 of the first impeller 74, and a third outlet opening 164 aligned with the fifth cooling duct 154 and the third inlet opening 158 of the first impeller 74.

[0061] The third inlet opening 158 of the first impeller 74 has an inlet geometric center 166 that defines a third inlet radius R11 between the inlet geometric center 166 of the third inlet opening 158 of the first impeller 74 and the rotor axis RA. Similarly, the third outlet opening 164 of the second impeller 80 has an outlet geometric center 168 that defines a third outlet radius R12 between the outlet geometric center 168 of the third outlet opening 164 of the second impeller 80 and the rotor axis RA. The third inlet opening 162 of the second impeller 80 has an inlet geometric center 170 that defines a third inlet radius R13 between the inlet geometric center 170 of the third inlet opening 162 of the second impeller 80 and the rotor axis RA. The third outlet opening 160 of the first impeller 74 has an outlet geometric center 172 that defines a third outlet radius R14 between the outlet geometric center 172 of the third outlet opening 160 of the first impeller 74 and the rotor axis RA.

[0062] Typically, the third outlet radius R12 defined between the outlet geometric center 168 of the third outlet opening 164 of the second impeller 80 and the rotor axis RA is greater than the third inlet radius R11 defined between the inlet geometric center 166 of the third inlet opening 158 of the first impeller 74 and the rotor axis RA, such that the first impeller 74 and the second impeller 80 are adapted to direct an air flow in a first direction through the fifth cooling duct 154 from the first rotor end 60 to the second rotor end 62 when the rotor 58, the first impeller 74, and the second impeller 80 rotate about the rotor axis RA. Similarly, the third outlet radius R14 defined between the outlet geometric center 172 of the third outlet opening 160 of the first impeller 74 and the rotor axis RA is greater than the third inlet radius R13 defined between the inlet geometric center 170 of the third inlet opening 162 of the second impeller 80 and the rotor axis RA, such that the first impeller 74 and the second impeller 80 are adapted to direct an air flow in a second direction opposite to the first direction through the sixth cooling duct 156 from the second rotor end 62 to the first rotor end 60 when the rotor 58, the first impeller 74, and the second impeller 80 rotate about the rotor axis RA.

[0063] Continuing to refer Figures 10 - 16 to, the first impeller 74 may include a third impeller arm 174 extending from the first hub portion 102 and away from the rotor axis RA, wherein the third impeller arm 174 defines the third inlet opening 158 of the first impeller 74 and the third outlet opening 160 of the first impeller 74. Similarly, the second impeller 80 may include a third impeller arm 182 extending from the second hub portion 118 and away from the rotor axis RA, wherein the third impeller arm 182 of the second impeller 80 defines the third inlet opening 162 of the second impeller 80 and the third outlet opening 164 of the second impeller 80.

[0064] It should be appreciated that the first impeller 74 and the second impeller 80 shown throughout the figures may be mirror image components of each other with respect to the rotor axis RA. It should also be appreciated that the first impeller 74 and the second impeller 80 may be replicas of each other with respect to the rotor axis RA.

[0065] As described above, the cross-sectional area of the inlet opening 76 with respect to the rotor axis RA defined by the first impeller 74 may be greater than the cross-sectional area of the outlet opening 84 defined by the second impeller 80. Similarly, when the first impeller 74 and the second impeller 80 define more than one inlet opening and outlet opening, the cross-sectional area of the inlet opening with respect to the rotor axis RA defined by one of the first impeller 74 and the second impeller 80 may be less than the cross-sectional area of the outlet opening with respect to the rotor axis RA defined by the other of the first impeller 74 and the second impeller 80.

[0066] It should be appreciated that the first impeller 74 and the second impeller 80 may have zero, one, two, three, four, five, six, seven, or eight or more impeller arms. Similarly, it should be appreciated that each of the first impeller arm 74 and the second impeller arm 80 may have two, three, four, five, six, seven, or eight or more cooling ducts.

[0067] As Figure 3 , Figure 17 and Figure 18As shown, the first impeller arm 104 of the first impeller 74 can define a vortex channel 190 between the first impeller arm 104 and the stator 68. It should be appreciated that each of the impeller arms (e.g., the first impeller arm 104 of the first impeller 74, the second impeller arm 106, and the third impeller arm 174) can each define a vortex channel 190 between each respective impeller arm and the stator of the motor 52 or another component. In an embodiment where the first impeller 74 has a fourth impeller arm 176, a fifth impeller arm 178, and a sixth impeller arm 180, each of the impeller arms can define a vortex channel 190 between each respective impeller arm and the stator 68 of the motor 52 or another component. When present, the vortex channel 190 can increase the flow rate of the fluid through the first cooling duct 70 and the second cooling duct 72 (and the third cooling duct 134, the fourth cooling duct 136, the fifth cooling duct 154, and / or the sixth cooling duct 156 (when present)). Additionally, when present, the vortex channel 190 reduces the air resistance against the first impeller 74 and the second impeller 76, allowing the first impeller 74 and the second impeller 76 and thus the rotor 58 and the shaft 64 to rotate at a higher desired rate. The thickness of the vortex channel 190 can be adjusted based on the expected mass flow rate through the first cooling duct 70 and the second cooling duct 72 (and the third cooling duct 134, the fourth cooling duct 136, the fifth cooling duct 154, and / or the sixth cooling duct 156 (when present)). For example, if a higher mass flow rate is desired through the first cooling duct 70 and the second cooling duct 72, the vortex channel 190 can be wider compared to when a lower mass flow rate is desired through the first cooling duct 70 and the second cooling duct 72 (and the third cooling duct 134, the fourth cooling duct 136, the fifth cooling duct 154, and / or the sixth cooling duct 156 (when present)).

[0068] It should also be appreciated that the system including the motor 52 can further include a gearbox heat exchanger. In such a system, the first impeller 74 and / or the second impeller 80 can be configured to direct an air flow to the gearbox heat exchanger for cooling the gearbox heat exchanger or any other component in the system.

[0069] The rotor assembly 50 can include a first oil passage 192 and a second oil passage, as Figure 19 and Figure 20As shown. When present, the first oil passage 192 is configured to direct oil to the first cooling duct 70 adjacent to the first impeller 74, and the second oil passage 194 is configured to direct oil to the second cooling duct 72 adjacent to the second impeller 76. When present, the first oil passage 192 is fluidly coupled to the first cooling duct 70 such that oil and air are mixed within the first cooling duct 70 during operation of the rotor assembly, and the second oil passage 194 is fluidly coupled to the second cooling duct 72 such that oil and air are mixed within the second cooling duct 72 during operation of the rotor assembly 50.

[0070] It is to be appreciated that the first oil cooling passage 192 and the second oil cooling passage 194 can be used in the rotor assembly 50 with any of the embodiments of the rotor assembly 50 described above (such as different embodiments of the first impeller 74 and the second impeller 80). Fluidly coupling the first oil passage 192 to the first cooling duct 70 such that oil and air are mixed within the first cooling duct 70 during operation of the rotor assembly, and fluidly coupling the second oil passage 194 to the second cooling duct 72 such that oil and air are mixed within the second cooling duct 72 during operation of the rotor assembly 50, improves the cooling capacity of the rotor assembly 50 because the oil and air mixture flowing through the first cooling duct 70 and the second cooling duct 72 improves heat dissipation compared to when only air passes through the first cooling duct 70 and the second cooling duct 72. This is particularly important in certain electric motors (such as when the electric motor 52 has a rotational speed of the shaft 64 greater than 23,000 revolutions per minute).

[0071] Continuing to refer Figure 4 , the first rotor end 60 has a first rotor face 94, and the second rotor end 62 has a second rotor face 96 that faces opposite the first rotor face 94 relative to the rotor axis RA. Referring Figure 19 and Figure 20 , the first oil passage 192 can be defined between the first rotor face 94 and the first impeller 74, and the second oil passage 194 can be defined between the second rotor face 96 and the second impeller 80. The first oil passage 192 can be directly fluidly coupled to the inlet opening 76 of the first impeller 74 such that the inlet opening 76 of the first impeller 74 is configured to direct and mix oil with air into the first cooling duct 70, and the second oil passage 194 can be directly fluidly coupled to the inlet opening 82 of the second impeller 80 such that the inlet opening 82 of the second impeller 80 is configured to direct and mix oil with air into the second cooling duct 72.

[0072] Although not explicitly shown in the drawings, the rotor assembly 50 may include a third oil passage configured to direct oil to a third cooling duct 134 adjacent to the first impeller 74 and a fourth oil passage configured to direct oil to a fourth cooling duct 136 adjacent to the second impeller 76. Similar to the first oil passage 192 and the second oil passage 194, when present, the third oil passage is fluidly coupled to the third cooling duct 134 such that oil and air are mixed within the third cooling duct 134 during operation of the rotor assembly 50, and when present, the fourth oil passage is fluidly coupled to the fourth cooling duct 136 such that oil and air are mixed within the fourth cooling duct 136 during operation of the rotor assembly 50. Further, similar to the first oil passage 192 and the second oil passage 194, the third oil passage may be directly fluidly coupled to a second inlet opening 138 of the first impeller 74 such that the second inlet opening 138 of the first impeller 74 is configured to direct and mix oil with air into the third cooling duct 134, and the fourth oil passage may be directly fluidly coupled to a second inlet opening 142 of the second impeller 80 such that the second inlet opening 142 of the second impeller 80 is configured to direct and mix oil with air into the fourth cooling duct 136. It is to be appreciated that the rotor assembly 50 may have any number of oil cooling passages (such as a fifth oil cooling passage and a sixth oil cooling passage) that are configured to direct oil to cooling ducts such as a fifth cooling duct 154 and a sixth cooling duct 156 to allow the first impeller 74 and the second impeller 80 to mix oil and air within the fifth cooling duct 154 and the sixth cooling duct 156. Such additional oil passages may be similarly configured to each respective cooling duct as shown with respect to Figure 19 and Figure 20 the second cooling duct 72 in

[0073] The shaft 64 may define at least a portion of the first oil passage 192 and the second oil passage 194. In other embodiments, the first oil passage 192 may be defined by the shaft 64 to direct oil to a first cooling duct 70 adjacent to the first impeller 74, and the second oil passage 194 may be defined by the shaft 64 to direct oil to a second cooling duct 72 adjacent to the second impeller 80. Similarly, when present, the shaft 64 may define at least a portion of the third oil passage and the fourth oil passage, and the shaft 64 may define at least a portion of the fifth oil passage and the sixth oil passage.

[0074] Claim 1: A rotor assembly for use in an electric machine, the rotor assembly comprising: A rotor that extends along a rotor axis and is adapted to rotate about the rotor axis, wherein the rotor has a first rotor end and a second rotor end spaced from the first rotor end relative to the rotor axis, wherein the rotor defines a first cooling duct extending from the first rotor end to the second rotor end, and wherein the rotor defines a second cooling duct extending from the first rotor end to the second rotor end; A first impeller coupled to the first rotor end, wherein the first impeller defines an inlet opening aligned with the first cooling duct, and wherein the first impeller defines an outlet opening aligned with the second cooling duct; and A second impeller coupled to the second rotor end such that the rotor is disposed between the first impeller and the second impeller relative to the rotor axis, wherein the second impeller defines an inlet opening aligned with the second cooling duct and the outlet opening of the first impeller, and wherein the second impeller defines an outlet opening aligned with the first cooling duct and the inlet opening of the first impeller; wherein the inlet opening of the first impeller has an inlet geometric center, and wherein the inlet geometric center of the inlet opening of the first impeller defines a first inlet radius between the inlet geometric center of the inlet opening of the first impeller and the rotor axis, wherein the outlet opening of the second impeller has an outlet geometric center, and wherein the outlet geometric center of the outlet opening of the second impeller defines a first outlet radius between the outlet geometric center of the outlet opening of the second impeller and the rotor axis; wherein the inlet opening of the second impeller has an inlet geometric center, and wherein the inlet geometric center of the inlet opening of the second impeller defines a first inlet radius between the inlet geometric center of the inlet opening of the second impeller and the rotor axis; wherein the outlet opening of the first impeller has an outlet geometric center, and wherein the outlet geometric center of the outlet opening of the first impeller defines a first outlet radius between the outlet geometric center of the outlet opening of the first impeller and the rotor axis; and, Wherein, a first outlet radius defined between the outlet geometric center of the outlet opening of the second impeller and the rotor axis is greater than a first inlet radius defined between the inlet geometric center of the inlet opening of the first impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct an air flow in a first direction through the first cooling duct from the first rotor end to the second rotor end when the rotor, the first impeller, and the second impeller rotate about the rotor axis, and wherein, a first outlet radius defined between the outlet geometric center of the outlet opening of the first impeller and the rotor axis is greater than a first inlet radius defined between the inlet geometric center of the inlet opening of the second impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct an air flow in a second direction opposite to the first direction through the second cooling duct from the second rotor end to the first rotor end.

[0075] Claim 2: The rotor assembly as set forth in Claim 1, wherein the first impeller has a first hub portion, and wherein the first impeller includes: a first impeller arm extending from the first hub portion and away from the rotor axis and defining the inlet opening of the first impeller; and a second impeller arm extending from the first hub portion away from the rotor axis and defining the outlet opening of the first impeller.

[0076] Claim 3: The rotor assembly as set forth in any of the preceding claims, wherein the first hub portion has an outer first hub surface disposed between the first impeller arm and the second impeller arm of the first impeller, wherein the outer first hub surface defines an outer first hub radius between the outer first hub surface and the rotor axis, and wherein the first impeller arm and the second impeller arm of the first impeller project away from the outer first hub surface relative to the rotor axis.

[0077] Claim 4: The rotor assembly as set forth in Claim 3, wherein the outlet opening of the first impeller is disposed outside the outer first hub radius relative to the rotor axis.

[0078] Claim 5: The rotor assembly as set forth in any of the preceding claims, wherein the inlet opening of the first impeller is disposed outside the outer first hub radius relative to the rotor axis.

[0079] Claim 6: The rotor assembly as set forth in any of the preceding claims, wherein the outlet opening of the first impeller has a curved or angled configuration relative to the rotor axis.

[0080] Claim 7: The rotor assembly as set forth in Claim 6, wherein the outlet opening of the first impeller is curved or angled in a clockwise configuration relative to the rotor axis.

[0081] Claim 8: The rotor assembly as set forth in Claim 6, wherein the outlet opening of the first impeller is curved or angled in a counterclockwise configuration relative to the rotor axis.

[0082] Claim 9: The rotor assembly as set forth in one of Claims 1 - 5, wherein the outlet opening of the first impeller has a straight configuration relative to the rotor axis.

[0083] Claim 10: The rotor assembly as set forth in any of the foregoing claims, wherein the first impeller has a first impeller surface facing the rotor, and wherein the outlet opening of the first impeller is defined by the first impeller surface of the first impeller.

[0084] Claim 11: The rotor assembly as set forth in Claim 10, wherein the outlet opening of the first impeller is partially defined through the first impeller.

[0085] Claim 12: The rotor assembly as set forth in Claim 11, wherein the first impeller has a second impeller surface opposite the first impeller surface of the first impeller relative to the rotor axis, wherein the first impeller has a first impeller thickness defined between the first impeller surface and the second impeller surface of the first impeller, and wherein the outlet opening of the first impeller has an outlet depth relative to the rotor axis that is less than the first impeller thickness.

[0086] Claim 13: The rotor assembly as set forth in any of the foregoing claims, wherein the inlet opening of the first impeller has a symmetric configuration relative to the rotor axis.

[0087] Claim 14: The rotor assembly as set forth in Claim 13, wherein the inlet opening of the first impeller has a semi - circular configuration.

[0088] Claim 15: The rotor assembly as set forth in any of the foregoing claims, wherein the first impeller arm and the second impeller arm of the first impeller are radially spaced 180 degrees from each other relative to the rotor axis.

[0089] Statement 16: A rotor assembly as set forth in any of the foregoing statements, wherein the second impeller has a second hub portion, and wherein the second impeller includes: a first impeller arm that extends from the second hub portion and away from the rotor axis and defines the inlet opening of the second impeller; and a second impeller arm that extends from the second hub portion away from the rotor axis and defines the outlet opening of the second impeller.

[0090] Statement 17: A rotor assembly as set forth in any of the foregoing statements, wherein the second hub portion has an outer second hub surface disposed between the first impeller arm and the second impeller arm of the second impeller, wherein the outer second hub surface defines an outer second hub radius between the outer second hub surface and the rotor axis, and wherein the first impeller arm and the second impeller arm of the second impeller project away from the outer second hub surface relative to the rotor axis.

[0091] Statement 18: A rotor assembly as set forth in any of the foregoing statements, wherein the outlet opening of the second impeller is disposed outside the outer second hub radius relative to the rotor axis.

[0092] Statement 19: A rotor assembly as set forth in any of the foregoing statements, wherein the inlet opening of the second impeller is disposed outside the outer second hub radius relative to the rotor axis.

[0093] Statement 20: A rotor assembly as set forth in any of the foregoing statements, wherein the outlet opening of the second impeller has a curved or angled configuration relative to the rotor axis.

[0094] Statement 21: A rotor assembly as set forth in Statement 20, wherein the outlet opening of the second impeller is curved or angled relative to the rotor axis in a clockwise configuration.

[0095] Statement 22: A rotor assembly as set forth in Statement 20, wherein the outlet opening of the second impeller is curved or angled relative to the rotor axis in a counterclockwise configuration.

[0096] Statement 23: A rotor assembly as set forth in one of Statements 16 - 19, wherein the outlet opening of the second impeller has a straight configuration relative to the rotor axis.

[0097] Statement 24: A rotor assembly as set forth in any of the foregoing statements, wherein the second impeller has a first impeller surface facing the rotor, and wherein the outlet opening of the second impeller is defined by the second impeller surface of the second impeller.

[0098] Claim 25: The rotor assembly as set forth in Claim 24, wherein the outlet opening of the second impeller is partially defined by the first impeller.

[0099] Claim 26: The rotor assembly as set forth in Claim 25, wherein the second impeller has a second impeller surface opposite the first impeller surface of the second impeller relative to the rotor axis, wherein the second impeller has a second impeller thickness defined between the first impeller surface and the second impeller surface of the second impeller, and wherein the outlet opening of the second impeller has an outlet depth relative to the rotor axis that is less than the second impeller thickness.

[0100] Claim 27: The rotor assembly as set forth in any of the preceding claims, wherein the rotor defines a third cooling duct extending from the first rotor end to the second rotor end and a fourth cooling duct extending from the first rotor end to the second rotor end; wherein the first impeller defines a second inlet opening aligned with the third cooling duct, and wherein the first impeller defines a second outlet opening aligned with the fourth cooling duct; and, wherein the second impeller defines a second inlet opening aligned with the fourth cooling duct and the second outlet opening of the first impeller, and wherein the second impeller defines a second outlet opening aligned with the third cooling duct and the second inlet opening of the first impeller.

[0101] Claim 28: The rotor assembly as set forth in Claim 27, wherein the second inlet opening of the first impeller has an inlet geometric center, and wherein the inlet geometric center of the second inlet opening of the first impeller defines a second inlet radius between the inlet geometric center of the second inlet opening of the first impeller and the rotor axis, wherein the second outlet opening of the second impeller has an outlet geometric center, and wherein the outlet geometric center of the second outlet opening of the second impeller defines a second outlet radius between the outlet geometric center of the second outlet opening of the second impeller and the rotor axis; wherein the second inlet opening of the second impeller has an inlet geometric center, and wherein the inlet geometric center of the second inlet opening of the second impeller defines a second inlet radius between the inlet geometric center of the second inlet opening of the second impeller and the rotor axis; and, Wherein, the second outlet opening of the first impeller has an outlet geometric center, and wherein, the outlet geometric center of the second outlet opening of the first impeller defines a second outlet radius between the outlet geometric center of the second outlet opening of the first impeller and the rotor axis.

[0102] Claim 29: The rotor assembly as set forth in Claim 28, wherein the second outlet radius defined between the outlet geometric center of the second outlet opening of the second impeller and the rotor axis is greater than the second inlet radius defined between the inlet geometric center of the second inlet opening of the first impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct an air flow in the first direction through the third cooling duct from the first rotor end to the second rotor end when the rotor, the first impeller, and the second impeller rotate about the rotor axis, and wherein the second outlet radius defined between the outlet geometric center of the second outlet opening of the first impeller and the rotor axis is greater than the second inlet radius defined between the inlet geometric center of the second inlet opening of the second impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct an air flow in the second direction opposite to the first direction through the fourth cooling duct from the second rotor end to the first rotor end.

[0103] Claim 30: The rotor assembly as set forth in any one of Claims 27 - 29, wherein the rotor defines a fifth cooling duct extending from the first rotor end to the second rotor end and a sixth cooling duct extending from the first rotor end to the second rotor end; wherein the first impeller defines a third inlet opening aligned with the fifth cooling duct, and wherein the first impeller defines a third outlet opening aligned with the sixth cooling duct; and wherein the second impeller defines a third inlet opening aligned with the sixth cooling duct and the third outlet opening of the first impeller, and wherein the second impeller defines a third outlet opening aligned with the fifth cooling duct and the third inlet opening of the first impeller.

[0104] Claim 31: The rotor assembly as set forth in Claim 30, wherein the third inlet opening of the first impeller has an inlet geometric center, and wherein the inlet geometric center of the third inlet opening of the first impeller defines a third inlet radius between the inlet geometric center of the third inlet opening of the first impeller and the rotor axis, Wherein, the third outlet opening of the second impeller has an outlet geometric center, and wherein, the outlet geometric center of the third outlet opening of the second impeller defines a third outlet radius between the outlet geometric center of the third outlet opening of the second impeller and the rotor axis; Wherein, the third inlet opening of the second impeller has an inlet geometric center, and wherein, the inlet geometric center of the third inlet opening of the second impeller defines a third inlet radius between the inlet geometric center of the third inlet opening of the second impeller and the rotor axis; and, Wherein, the third outlet opening of the first impeller has an outlet geometric center, and wherein, the outlet geometric center of the third outlet opening of the first impeller defines a third outlet radius between the outlet geometric center of the third outlet opening of the first impeller and the rotor axis.

[0105] Claim 32: The rotor assembly as set forth in Claim 31, wherein, the third outlet radius defined between the outlet geometric center of the third outlet opening of the second impeller and the rotor axis is greater than the third inlet radius defined between the inlet geometric center of the third inlet opening of the first impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct an air flow in the first direction through the fifth cooling duct from the first rotor end to the second rotor end when the rotor, the first impeller, and the second impeller rotate about the rotor axis, and wherein, the third outlet radius defined between the outlet geometric center of the third outlet opening of the first impeller and the rotor axis is greater than the third inlet radius defined between the inlet geometric center of the third inlet opening of the second impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct an air flow in the second direction opposite to the first direction through the sixth cooling duct from the second rotor end to the first rotor end when the rotor, the first impeller, and the second impeller rotate about the rotor axis.

[0106] Claim 33: The rotor assembly as set forth in any one of Claims 27 - 32, wherein, the first inlet opening of the first impeller, the first outlet opening of the first impeller, the second inlet opening of the first impeller, the second outlet opening of the first impeller, the third inlet opening of the first impeller, and the third outlet opening of the first impeller are equally radially spaced from each other with respect to and around the rotor axis.

[0107] Claim 34: A rotor assembly as set forth in any one of Claims 27 - 33, wherein the first inlet opening of the second impeller, the first outlet opening of the second impeller, the second inlet opening of the second impeller, the second outlet opening of the second impeller, the third inlet opening of the second impeller, and the third outlet opening of the second impeller are equally radially spaced from each other with respect to and around the rotor axis.

[0108] Claim 35: A rotor assembly as set forth in any one of Claims 27 - 34, wherein the first impeller includes: a third impeller arm extending from the first hub portion and away from the rotor axis and defining the second inlet opening of the first impeller; a fourth impeller arm extending from the first hub portion away from the rotor axis and defining the second outlet opening of the first impeller; a fifth impeller arm extending from the first hub portion away from the rotor axis and defining the third inlet opening of the first impeller; and a sixth impeller arm extending from the first hub portion away from the rotor axis and defining the third outlet opening of the first impeller.

[0109] Claim 36: A rotor assembly as set forth in any one of Claims 27 - 35, wherein the second impeller includes: a third impeller arm extending from the second hub portion and away from the rotor axis and defining the second inlet opening of the second impeller; a fourth impeller arm extending from the second hub portion away from the rotor axis and defining the second outlet opening of the second impeller; a fifth impeller arm extending from the second hub portion away from the rotor axis and defining the third inlet opening of the second impeller; and a sixth impeller arm extending from the second hub portion away from the rotor axis and defining the third outlet opening of the second impeller.

[0110] Claim 37: A rotor assembly as set forth in Claim 1, wherein the first impeller has a first hub portion, and wherein the first impeller includes a first impeller arm extending from the first hub portion and away from the rotor axis and defining the inlet opening of the first impeller and the outlet opening of the first impeller.

[0111] Claim 38: A rotor assembly as set forth in Claim 37, wherein the second impeller has a second hub portion, and wherein the second impeller includes a first impeller arm extending from the second hub portion and away from the rotor axis and defining the outlet opening of the second impeller and the inlet opening of the second impeller.

[0112] Claim 39: The rotor assembly as set forth in any one of Claims 37 and 38, wherein the rotor defines a third cooling duct extending from the first rotor end to the second rotor end and a fourth cooling duct extending from the first rotor end to the second rotor end; wherein the first impeller defines a second inlet opening aligned with the third cooling duct, and wherein the first impeller defines a second outlet opening aligned with the fourth cooling duct; and, wherein the second impeller defines a second inlet opening aligned with the fourth cooling duct and the second outlet opening of the first impeller, and wherein the second impeller defines a second outlet opening aligned with the third cooling duct and the second inlet opening of the first impeller.

[0113] Claim 40: The rotor assembly as set forth in any one of Claims 37 - 39, wherein the second inlet opening of the first impeller has an inlet geometric center, and wherein the inlet geometric center of the second inlet opening of the first impeller defines a second inlet radius between the inlet geometric center of the second inlet opening of the first impeller and the rotor axis, wherein the second outlet opening of the second impeller has an outlet geometric center, and wherein the outlet geometric center of the second outlet opening of the second impeller defines a second outlet radius between the outlet geometric center of the second outlet opening of the second impeller and the rotor axis; wherein the second inlet opening of the second impeller has an inlet geometric center, and wherein the inlet geometric center of the second inlet opening of the second impeller defines a second inlet radius between the inlet geometric center of the second inlet opening of the second impeller and the rotor axis; and, wherein the second outlet opening of the first impeller has an outlet geometric center, and wherein the outlet geometric center of the second outlet opening of the first impeller defines a second outlet radius between the outlet geometric center of the second outlet opening of the first impeller and the rotor axis.

[0114] Claim 41: A rotor assembly as set forth in Claim 40, wherein the second outlet radius defined between the outlet geometric center of the second outlet opening of the second impeller and the rotor axis is greater than the second inlet radius defined between the inlet geometric center of the second inlet opening of the first impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct an air flow in the first direction through the third cooling duct from the first rotor end to the second rotor end when the rotor, the first impeller, and the second impeller rotate about the rotor axis, and wherein the second outlet radius defined between the outlet geometric center of the second outlet opening of the first impeller and the rotor axis is greater than the second inlet radius defined between the inlet geometric center of the second inlet opening of the second impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct an air flow in the second direction opposite to the first direction through the fourth cooling duct from the second rotor end to the first rotor end.

[0115] Claim 42: A rotor assembly as set forth in any one of Claims 37 - 41, wherein the first impeller includes a second impeller arm that extends from the first hub portion and away from the rotor axis and defines the second inlet opening of the first impeller and the second outlet opening of the first impeller, and wherein the second impeller includes a second impeller arm that extends from the second hub portion and away from the rotor axis and defines the second inlet opening of the second impeller and the second outlet opening of the second impeller.

[0116] Claim 43: A rotor assembly as set forth in any one of Claims 39 - 42, wherein the rotor defines a fifth cooling duct extending from the first rotor end to the second rotor end and a sixth cooling duct extending from the first rotor end to the second rotor end; wherein the first impeller defines a third inlet opening aligned with the fifth cooling duct, and wherein the first impeller defines a third outlet opening aligned with the sixth cooling duct; and, wherein the second impeller defines a third inlet opening aligned with the sixth cooling duct and the third outlet opening of the first impeller, and wherein the second impeller defines a third outlet opening aligned with the fifth cooling duct and the third inlet opening of the first impeller.

[0117] Claim 44: A rotor assembly as set forth in Claim 43, Wherein, the third inlet opening of the first impeller has an inlet geometric center, and wherein, the inlet geometric center of the third inlet opening of the first impeller defines a third inlet radius between the inlet geometric center of the third inlet opening of the first impeller and the rotor axis, Wherein, the third outlet opening of the second impeller has an outlet geometric center, and wherein, the outlet geometric center of the third outlet opening of the second impeller defines a third outlet radius between the outlet geometric center of the third outlet opening of the second impeller and the rotor axis; Wherein, the third inlet opening of the second impeller has an inlet geometric center, and wherein, the inlet geometric center of the third inlet opening of the second impeller defines a third inlet radius between the inlet geometric center of the third inlet opening of the second impeller and the rotor axis; and, Wherein, the third outlet opening of the first impeller has an outlet geometric center, and wherein, the outlet geometric center of the third outlet opening of the first impeller defines a third outlet radius between the outlet geometric center of the third outlet opening of the first impeller and the rotor axis.

[0118] Claim 45: The rotor assembly as set forth in Claim 44, wherein the third outlet radius defined between the outlet geometric center of the third outlet opening of the second impeller and the rotor axis is greater than the third inlet radius defined between the inlet geometric center of the third inlet opening of the first impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct an air flow in the first direction through the fifth cooling duct from the first rotor end to the second rotor end when the rotor, the first impeller, and the second impeller rotate about the rotor axis, and wherein the third outlet radius defined between the outlet geometric center of the third outlet opening of the first impeller and the rotor axis is greater than the third inlet radius defined between the inlet geometric center of the third inlet opening of the second impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct an air flow in the second direction, opposite to the first direction, through the sixth cooling duct from the second rotor end to the first rotor end.

[0119] Claim 46: A rotor assembly as set forth in any of Claims 43 - 45, wherein the first impeller includes a third impeller arm that extends from the first hub portion and away from the rotor axis and defines the third inlet opening and the third outlet opening of the first impeller, and wherein the second impeller includes a third impeller arm that extends from the second hub portion and away from the rotor axis and defines the third inlet opening and the third outlet opening of the second impeller.

[0120] Claim 47: A rotor assembly as set forth in any of the preceding claims, wherein the first impeller and the second impeller are mirror image assemblies with respect to the rotor axis.

[0121] Claim 48: A rotor assembly as set forth in any of the preceding claims, wherein the first impeller, the second impeller, and the rotor are adapted to rotate consistently about the rotor axis.

[0122] Claim 49: A rotor assembly as set forth in any of the preceding claims, wherein the first rotor end has a first rotor face, and the second rotor end has a second rotor face that faces opposite to the first rotor face with respect to the rotor axis, and wherein the first impeller engages with the first rotor face, and the second impeller engages with the second rotor face.

[0123] Claim 50: A rotor assembly as set forth in any of the preceding claims further includes a plurality of magnets disposed in the rotor.

[0124] Claim 51: A rotor assembly as set forth in Claim 50, wherein the rotor defines a plurality of magnet channels adjacent to the magnets, and wherein the plurality of magnet channels are filled with an injection - molded material.

[0125] Claim 52: A rotor assembly as set forth in Claim 50, wherein the plurality of magnet channels are hollow.

[0126] Claim 53: A rotor assembly as set forth in Claim 52, wherein the first impeller defines a magnet opening configured to align with at least one of the magnet channels among the plurality of magnet channels, and wherein the second impeller defines a magnet opening configured to align with at least one of the magnet channels among the plurality of magnet channels.

[0127] Claim 54: An electric motor, which includes the rotor assembly as set forth in any of the preceding claims, and further includes: A shaft extending along the rotor axis, wherein the rotor defines an interior of the rotor, and the shaft is disposed within the interior of the rotor and coupled to the rotor; and A stator coupled to the rotor and disposed around the rotor relative to the rotor axis.

[0128] Claim 55: The electric machine as set forth in Claim 54, wherein the first impeller arm of the first impeller defines a vortex channel between the first impeller arm and the stator.

[0129] Claim 56: A system comprising the electric machine as set forth in any one of Claims 54 and 55, and further comprising a gearbox heat exchanger, wherein the first impeller and the second impeller are configured to direct an air flow to the gearbox heat exchanger for cooling the gearbox heat exchanger.

[0130] Claim 57: The rotor assembly as set forth in any one of the foregoing claims, wherein the rotor assembly further comprises, A first oil passage configured to direct oil to the first cooling pipe adjacent to the first impeller; and A second oil passage configured to direct oil to the second cooling pipe adjacent to the second impeller; wherein the first oil passage is fluidly coupled to the first cooling pipe such that oil and air are mixed within the first cooling pipe during operation of the rotor assembly, and wherein the second oil passage is fluidly coupled to the second cooling pipe such that oil and air are mixed within the second cooling pipe during operation of the rotor assembly.

[0131] Claim 58: A rotor assembly for an electric machine, the rotor assembly comprising: A rotor extending along a rotor axis and adapted to be rotatable about the rotor axis, wherein the rotor has a first rotor end and a second rotor end spaced from the first rotor end relative to the rotor axis, wherein the rotor defines a first cooling pipe extending from the first rotor end to the second rotor end, and wherein the rotor defines a second cooling pipe extending from the first rotor end to the second rotor end; A first impeller coupled to the first rotor end, wherein the first impeller defines an inlet opening aligned with the first cooling pipe, and wherein the first impeller defines an outlet opening aligned with the second cooling pipe; A second impeller, which is coupled to the second rotor end such that the rotor is disposed between the first impeller and the second impeller relative to the rotor axis, wherein the second impeller defines an inlet opening that is aligned with the second cooling duct and the outlet opening of the first impeller, and wherein the second impeller defines an outlet opening that is aligned with the first cooling duct and the inlet opening of the first impeller; A first oil passage configured to direct oil to the first cooling duct adjacent to the first impeller; and A second oil passage configured to direct oil to the second cooling duct adjacent to the second impeller; wherein the first oil passage is fluidly coupled to the first cooling duct such that oil and air are mixed within the first cooling duct during operation of the rotor assembly, and wherein the second oil passage is fluidly coupled to the second cooling duct such that oil and air are mixed within the second cooling duct during operation of the rotor assembly.

[0132] Claim 59: The rotor assembly as set forth in Claim 58, wherein the first rotor end has a first rotor face, and the second rotor end has a second rotor face facing opposite to the first rotor face relative to the rotor axis, wherein the first oil passage is defined between the first rotor face and the first impeller, and wherein the second oil passage is defined between the second rotor face and the second impeller.

[0133] Claim 60: The rotor assembly as set forth in Claim 59, wherein the first oil passage is directly fluidly coupled to the inlet opening of the first impeller such that the inlet opening of the first impeller is configured to direct and mix oil and air into the first cooling duct, and wherein the second oil passage is directly fluidly coupled to the inlet opening of the second impeller such that the inlet opening of the second impeller is configured to direct and mix oil and air into the second cooling duct.

[0134] Claim 61: The rotor assembly as set forth in any one of the claims, wherein the inlet opening of the first impeller has an inlet geometric center, and wherein a first inlet radius is defined between the inlet geometric center of the inlet opening of the first impeller and the rotor axis at the inlet geometric center of the inlet opening of the first impeller, wherein the outlet opening of the second impeller has an outlet geometric center, and wherein a first outlet radius is defined between the outlet geometric center of the outlet opening of the second impeller and the rotor axis at the outlet geometric center of the outlet opening of the second impeller, Wherein, the inlet opening of the second impeller has an inlet geometric center, and wherein, the inlet geometric center of the inlet opening of the second impeller defines a first inlet radius between the inlet geometric center of the inlet opening of the second impeller and the rotor axis, Wherein, the outlet opening of the first impeller has an outlet geometric center, and wherein, the outlet geometric center of the outlet opening of the first impeller defines a first outlet radius between the outlet geometric center of the outlet opening of the first impeller and the rotor axis, and, Wherein, the first outlet radius defined between the outlet geometric center of the outlet opening of the second impeller and the rotor axis is greater than the first inlet radius defined between the inlet geometric center of the inlet opening of the first impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct a fluid flow of air and oil in a first direction through the first cooling duct from the first rotor end to the second rotor end when the rotor, the first impeller, and the second impeller rotate about the rotor axis, and wherein, the first outlet radius defined between the outlet geometric center of the outlet opening of the first impeller and the rotor axis is greater than the first inlet radius defined between the inlet geometric center of the inlet opening of the second impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct a fluid flow of air and oil in a second direction opposite to the first direction through the second cooling duct from the second rotor end to the first rotor end.

[0135] Claim 62: The rotor assembly as set forth in Claim 61, wherein the first impeller has a first hub portion, and wherein the first impeller includes: a first impeller arm that extends from the first hub portion and away from the rotor axis and defines the inlet opening of the first impeller; and a second impeller arm that extends from the first hub portion away from the rotor axis and defines the outlet opening of the first impeller.

[0136] Claim 63: The rotor assembly as set forth in Claim 62, wherein the first hub portion has an outer first hub surface disposed between the first impeller arm and the second impeller arm of the first impeller, wherein the outer first hub surface defines an outer first hub radius between the outer first hub surface and the rotor axis, and wherein the first impeller arm and the second impeller arm of the first impeller project away from the outer first hub surface relative to the rotor axis.

[0137] Claim 64: The rotor assembly as set forth in Claim 63, wherein the outlet opening of the first impeller is disposed outside the outer first hub radius relative to the rotor axis.

[0138] Claim 65: The rotor assembly as set forth in any one of Claims 63 and 64, wherein the inlet opening of the first impeller is disposed outside the outer first hub radius relative to the rotor axis.

[0139] Claim 66: The rotor assembly as set forth in any one of Claims 58 - 65, wherein the second impeller has a second hub portion, and wherein the second impeller includes: a first impeller arm that extends from the second hub portion and away from the rotor axis and defines the inlet opening of the second impeller; and a second impeller arm that extends from the second hub portion away from the rotor axis and defines the outlet opening of the second impeller.

[0140] Claim 67: The rotor assembly as set forth in any one of Claims 58 - 66, wherein the first impeller has a first impeller surface facing the rotor, and wherein the outlet opening of the first impeller is defined by the first impeller surface of the first impeller.

[0141] Claim 68: The rotor assembly as set forth in Claim 67, wherein the first impeller has a second impeller surface opposite the first impeller surface of the first impeller relative to the rotor axis, wherein the first impeller has a first impeller thickness defined between the first impeller surface and the second impeller surface of the first impeller, and wherein the outlet opening of the first impeller has an outlet depth relative to the rotor axis that is less than the first impeller thickness.

[0142] Claim 69: The rotor assembly as set forth in any one of Claims 58 - 68, wherein the rotor defines a third cooling duct extending from the first rotor end to the second rotor end and a fourth cooling duct extending from the first rotor end to the second rotor end; wherein the first impeller defines a second inlet opening aligned with the third cooling duct, and wherein the first impeller defines a second outlet opening aligned with the fourth cooling duct; wherein the second impeller defines a second inlet opening aligned with the fourth cooling duct and the second outlet opening of the first impeller, and wherein the second impeller defines a second outlet opening aligned with the third cooling duct and the second inlet opening of the first impeller; A third oil passage configured to direct oil to the third cooling duct adjacent to the first impeller; and, The fourth oil passage is configured to direct oil to the fourth cooling pipe adjacent to the second impeller; Wherein, the third oil passage is fluidly coupled to the third cooling pipe such that oil and air are mixed within the third cooling pipe during operation of the rotor assembly, and wherein, the fourth oil passage is fluidly coupled to the fourth cooling pipe such that oil and air are mixed within the fourth cooling pipe during operation of the rotor assembly.

[0143] Claim 70: The rotor assembly as set forth in Claim 69, wherein the third oil passage is directly fluidly coupled to the second inlet opening of the first impeller such that the second inlet opening of the first impeller is configured to direct and mix oil together with air into the third cooling pipe, and wherein the fourth oil passage is directly fluidly coupled to the second inlet opening of the second impeller such that the second inlet opening of the second impeller is configured to direct and mix oil together with air into the fourth cooling pipe.

[0144] Claim 71: The rotor assembly as set forth in any one of Claims 69 and 70, Wherein, the second inlet opening of the first impeller has an inlet geometric center, and wherein the inlet geometric center of the second inlet opening of the first impeller defines a second inlet radius between the inlet geometric center of the second inlet opening of the first impeller and the rotor axis; Wherein, the second outlet opening of the second impeller has an outlet geometric center, and wherein the outlet geometric center of the second outlet opening of the second impeller defines a second outlet radius between the outlet geometric center of the second outlet opening of the second impeller and the rotor axis; Wherein, the second inlet opening of the second impeller has an inlet geometric center, and wherein the inlet geometric center of the second inlet opening of the second impeller defines a second inlet radius between the inlet geometric center of the second inlet opening of the second impeller and the rotor axis; and, Wherein, the second outlet opening of the first impeller has an outlet geometric center, and wherein the outlet geometric center of the second outlet opening of the first impeller defines a second outlet radius between the outlet geometric center of the second outlet opening of the first impeller and the rotor axis.

[0145] Claim 72: The rotor assembly as set forth in Claim 71, wherein the second outlet radius defined between the outlet geometric center of the second outlet opening of the second impeller and the rotor axis is greater than the second inlet radius defined between the inlet geometric center of the second inlet opening of the first impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct a fluid flow of air and oil in the first direction through the third cooling duct from the first rotor end to the second rotor end when the rotor, the first impeller, and the second impeller rotate about the rotor axis, and wherein the second outlet radius defined between the outlet geometric center of the second outlet opening of the first impeller and the rotor axis is greater than the second inlet radius defined between the inlet geometric center of the second inlet opening of the second impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct a fluid flow of air and oil in the second direction opposite to the first direction through the fourth cooling duct from the second rotor end to the first rotor end.

[0146] Claim 73: The rotor assembly as set forth in any one of Claims 58 - 72, further comprising a plurality of magnets disposed in the rotor.

[0147] Claim 74: The rotor assembly as set forth in Claim 73, wherein the rotor defines a plurality of magnet channels adjacent to the magnets, wherein the plurality of magnet channels are hollow, and wherein the first impeller defines a magnet opening configured to align with at least one of the magnet channels of the plurality of magnet channels, and wherein the second impeller defines a magnet opening configured to align with at least one of the magnet channels of the plurality of magnet channels.

[0148] Claim 75: An electric machine, comprising the rotor assembly as set forth in any one of Claims 58 - 74, and further comprising: a shaft extending along the rotor axis, wherein the rotor defines a rotor interior, and wherein the shaft is disposed within the rotor interior and coupled to the rotor; and a stator coupled to the rotor and disposed around the rotor relative to the rotor; wherein the shaft defines at least a portion of the first oil passage and the second oil passage.

[0149] Statement 76: The electric machine as set forth in Statement 75, wherein the first oil passage is defined by the shaft to guide oil to the first cooling pipe adjacent to the first impeller, and the second oil passage is defined by the shaft to guide oil to the second cooling pipe adjacent to the second impeller.

[0150] Statement 77: The electric machine as set forth in any one of Statements 75 and 76, wherein the first impeller arm of the first impeller defines a vortex passage between the first impeller arm and the stator.

Claims

1. A rotor assembly for an electric machine, the rotor assembly comprising: A rotor extending along a rotor axis and adapted to be rotatable about the rotor axis, wherein the rotor has a first rotor end and a second rotor end spaced from the first rotor end relative to the rotor axis, wherein the rotor defines a first cooling duct extending from the first rotor end to the second rotor end, and wherein the rotor defines a second cooling duct extending from the first rotor end to the second rotor end; A first impeller coupled to the first rotor end, wherein the first impeller defines an inlet opening aligned with the first cooling duct, and wherein the first impeller defines an outlet opening aligned with the second cooling duct; A second impeller coupled to the second rotor end such that the rotor is disposed between the first impeller and the second impeller relative to the rotor axis, wherein the second impeller defines an inlet opening aligned with the second cooling duct and the outlet opening of the first impeller, and wherein the second impeller defines an outlet opening aligned with the first cooling duct and the inlet opening of the first impeller; A first oil passage configured to direct oil to the first cooling duct adjacent to the first impeller; and A second oil passage configured to direct oil to the second cooling duct adjacent to the second impeller; Wherein the first oil passage is fluidly coupled to the first cooling duct such that oil and air are mixed within the first cooling duct during operation of the rotor assembly, and wherein the second oil passage is fluidly coupled to the second cooling duct such that oil and air are mixed within the second cooling duct during operation of the rotor assembly.

2. The rotor assembly according to claim 1, wherein, The first rotor end has a first rotor face, and the second rotor end has a second rotor face facing opposite to the first rotor face relative to the rotor axis, wherein the first oil passage is defined between the first rotor face and the first impeller, and wherein the second oil passage is defined between the second rotor face and the second impeller.

3. The rotor assembly according to claim 2, wherein, The first oil passage is directly fluidly coupled to the inlet opening of the first impeller such that the inlet opening of the first impeller is configured to direct and mix oil with air into the first cooling duct, and wherein the second oil passage is directly fluidly coupled to the inlet opening of the second impeller such that the inlet opening of the second impeller is configured to direct and mix oil with air into the second cooling duct.

4. The rotor assembly according to any one of the preceding claims, Among them, The inlet opening of the first impeller has an inlet geometric center, and wherein the inlet geometric center of the inlet opening of the first impeller defines a first inlet radius between the inlet geometric center of the inlet opening of the first impeller and the rotor axis, Wherein, the outlet opening of the second impeller has an outlet geometric center, and wherein, the outlet geometric center of the outlet opening of the second impeller defines a first outlet radius between the outlet geometric center of the outlet opening of the second impeller and the rotor axis, Wherein, the inlet opening of the second impeller has an inlet geometric center, and wherein, the inlet geometric center of the inlet opening of the second impeller defines a first inlet radius between the inlet geometric center of the inlet opening of the second impeller and the rotor axis, Wherein, the outlet opening of the first impeller has an outlet geometric center, and wherein, the outlet geometric center of the outlet opening of the first impeller defines a first outlet radius between the outlet geometric center of the outlet opening of the first impeller and the rotor axis, and, Wherein, the first outlet radius defined between the outlet geometric center of the outlet opening of the second impeller and the rotor axis is greater than the first inlet radius defined between the inlet geometric center of the inlet opening of the first impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct a fluid flow of air and oil in a first direction through the first cooling conduit from the first rotor end to the second rotor end when the rotor, the first impeller, and the second impeller rotate about the rotor axis, and wherein, the first outlet radius defined between the outlet geometric center of the outlet opening of the first impeller and the rotor axis is greater than the first inlet radius defined between the inlet geometric center of the inlet opening of the second impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct a fluid flow of air and oil in a second direction opposite to the first direction through the second cooling conduit from the second rotor end to the first rotor end.

5. The rotor assembly according to claim 4, wherein, The first impeller has a first hub portion, and wherein, the first impeller includes: a first impeller arm that extends from the first hub portion and away from the rotor axis and defines the inlet opening of the first impeller; and a second impeller arm that extends from the first hub portion away from the rotor axis and defines the outlet opening of the first impeller.

6. The rotor assembly according to claim 5, wherein, The first hub portion has an outer first hub surface disposed between the first impeller arm and the second impeller arm of the first impeller, wherein, the outer first hub surface defines an outer first hub radius between the outer first hub surface and the rotor axis, and wherein, the first impeller arm and the second impeller arm of the first impeller project away from the outer first hub surface relative to the rotor axis.

7. The rotor assembly according to claim 6, wherein, The outlet opening of the first impeller is disposed outside the outer first hub radius relative to the rotor axis.

8. The rotor assembly according to claim 6, wherein, The inlet opening of the first impeller is disposed outside the outer first hub radius relative to the rotor axis.

9. The rotor assembly according to claim 5, wherein, The second impeller has a second hub portion, and wherein the second impeller includes: a first impeller arm that extends from the second hub portion and away from the rotor axis and defines the inlet opening of the second impeller; and a second impeller arm that extends from the second hub portion away from the rotor axis and defines the outlet opening of the second impeller.

10. The rotor assembly according to any one of claims 1-3, wherein, The first impeller has a first impeller surface facing the rotor, and wherein the outlet opening of the first impeller is defined by the first impeller surface of the first impeller.

11. The rotor assembly according to claim 10, wherein, The first impeller has a second impeller surface opposite the first impeller surface of the first impeller relative to the rotor axis, wherein the first impeller has a first impeller thickness defined between the first impeller surface and the second impeller surface of the first impeller, and wherein the outlet opening of the first impeller has an outlet depth relative to the rotor axis that is less than the first impeller thickness.

12. The rotor assembly according to any one of claims 1-3, Among them, The rotor defines a third cooling duct extending from the first rotor end to the second rotor end and a fourth cooling duct extending from the first rotor end to the second rotor end; wherein the first impeller defines a second inlet opening aligned with the third cooling duct, and wherein the first impeller defines a second outlet opening aligned with the fourth cooling duct; wherein the second impeller defines a second inlet opening aligned with the fourth cooling duct and the second outlet opening of the first impeller, and wherein the second impeller defines a second outlet opening aligned with the third cooling duct and the second inlet opening of the first impeller; A third oil passage is configured to direct oil to the third cooling duct adjacent to the first impeller; and, A fourth oil passage is configured to direct oil to the fourth cooling duct adjacent to the second impeller; wherein the third oil passage is fluidly coupled to the third cooling duct such that oil and air are mixed within the third cooling duct during operation of the rotor assembly, and wherein the fourth oil passage is fluidly coupled to the fourth cooling duct such that oil and air are mixed within the fourth cooling duct during operation of the rotor assembly.

13. The rotor assembly according to claim 12, wherein, The third oil passage is directly fluidly coupled to the second inlet opening of the first impeller such that the second inlet opening of the first impeller is configured to direct and mix oil with air into the third cooling duct, and wherein the fourth oil passage is directly fluidly coupled to the second inlet opening of the second impeller such that the second inlet opening of the second impeller is configured to direct and mix oil with air into the fourth cooling duct.

14. The rotor assembly according to claim 12, Among them, The second inlet opening of the first impeller has an inlet geometric center, and wherein the inlet geometric center of the second inlet opening of the first impeller defines a second inlet radius between the inlet geometric center of the second inlet opening of the first impeller and the rotor axis; wherein the second outlet opening of the second impeller has an outlet geometric center, and wherein the outlet geometric center of the second outlet opening of the second impeller defines a second outlet radius between the outlet geometric center of the second outlet opening of the second impeller and the rotor axis; wherein the second inlet opening of the second impeller has an inlet geometric center, and wherein the inlet geometric center of the second inlet opening of the second impeller defines a second inlet radius between the inlet geometric center of the second inlet opening of the second impeller and the rotor axis; and, wherein the second outlet opening of the first impeller has an outlet geometric center, and wherein the outlet geometric center of the second outlet opening of the first impeller defines a second outlet radius between the outlet geometric center of the second outlet opening of the first impeller and the rotor axis.

15. The rotor assembly according to claim 14, wherein, The second outlet radius defined between the outlet geometric center of the second outlet opening of the second impeller and the rotor axis is greater than the second inlet radius defined between the inlet geometric center of the second inlet opening of the first impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct a fluid flow of air and oil in the first direction through the third cooling duct from the first rotor end to the second rotor end when the rotor, the first impeller, and the second impeller rotate about the rotor axis, and wherein the second outlet radius defined between the outlet geometric center of the second outlet opening of the first impeller and the rotor axis is greater than the second inlet radius defined between the inlet geometric center of the second inlet opening of the second impeller and the rotor axis, such that the first impeller and the second impeller are adapted to direct a fluid flow of air and oil in the second direction opposite to the first direction through the fourth cooling duct from the second rotor end to the first rotor end.

16. The rotor assembly according to any one of claims 1-3, further comprising a plurality of magnets disposed in the rotor.

17. The rotor assembly according to claim 16, wherein, The rotor defines a plurality of magnet channels adjacent to the magnets, wherein the plurality of magnet channels are hollow, and wherein the first impeller defines a magnet opening configured to align with at least one of the magnet channels in the plurality of magnet channels, and wherein the second impeller defines a magnet opening configured to align with at least one of the magnet channels in the plurality of magnet channels.

18. A motor, which includes a rotor assembly as described in any one of claims 1-3, and further includes: A shaft extending along the rotor axis, wherein the rotor defines an interior of the rotor, and the shaft is disposed within the interior of the rotor and coupled to the rotor; and A stator coupled to the rotor and disposed around the rotor relative to the rotor; Wherein the shaft defines at least a portion of the first oil passage and the second oil passage.

19. The electric machine according to claim 18, wherein, The first oil passage is defined by the shaft to direct oil to the first cooling pipe adjacent to the first impeller, and the second oil passage is defined by the shaft to direct oil to the second cooling pipe adjacent to the second impeller.

20. The electric machine according to claim 18, wherein, The first impeller arm of the first impeller defines a vortex passage between the first impeller arm and the stator.

Images