Axial brush assembly for electric machine

Abstract

The invention relates to an axial brush assembly for an electric machine. A rotor assembly includes a rotor shaft and a rotor core supported by the rotor shaft and surrounded by a plurality of windings. The rotor assembly also includes a first brush that engages a first slip ring that is fixed relative to the first distal end of the rotor shaft. The first brush includes one of a first conical protrusion or a first convex receptacle, and the first slip ring includes the other of the first conical protrusion or the first convex receptacle. A first electrical connection extends between the first slip ring and the plurality of windings. The second brush is configured to engage the second slip ring with the second slip ring fixed relative to the rotor shaft. A second electrical connection extends between the second slip ring and the plurality of windings.

Description

Technical Field

[0001] The present invention relates to an axial brush assembly for an electric machine. Background Art

[0002] Electric motors are used in a wide range of applications from operating small electromechanical devices to providing a primary source of propulsion for vehicles. An electric motor may include a stator fixed within a housing that causes a rotor to spin relative to the stator. In an example, the stator may include magnets that rotate in response to an electric field generated by the stator. In another example, the rotor includes windings around a rotor core that may be individually energized to cause the rotor to spin in response to the electric field generated by the stator. The windings may be energized by applying a voltage to the rotor windings through brushes that engage corresponding slip rings on the rotor shaft. Summary of the invention

[0003] A rotor assembly for an electric machine is disclosed herein. The rotor assembly includes a rotor shaft and a rotor core supported by the rotor shaft and surrounded by a plurality of windings. The rotor assembly also includes a first brush engaging a first slip ring fixed relative to a first distal end of the rotor shaft. The first brush includes one of a first conical protrusion or a first convex socket, and the first slip ring includes the other of the first conical protrusion or the first convex socket. A first electrical connector extends between the first slip ring and the plurality of windings. A second brush is configured to engage the second slip ring when the second slip ring is fixed relative to the rotor shaft. A second electrical connector extends between the second slip ring and the plurality of windings.

[0004] Another aspect of the present disclosure may be wherein the first brush is located in a first brush housing and the first brush is biased toward the first slip ring using a first spring element.

[0005] Another aspect of the present disclosure can be wherein the rotor shaft includes an internal passage having at least one internal conduit configured to accept at least one of the first electrical connector or the second electrical connector.

[0006] Another aspect of the present disclosure may be wherein the at least one inner conduit is constructed of a non-conductive material.

[0007] Another aspect of the present disclosure may be wherein at least one of the first electrical connector and the second electrical connector comprises a plurality of connections to a plurality of windings.

[0008] Another aspect of the present disclosure may be where the second brush includes one of a second conical protrusion or a second convex socket configured to engage the other of the second conical protrusion or the second convex socket on the second slip ring, and the second brush is located in a second brush housing. The second brush is biased toward the second slip ring using a second spring element.

[0009] Another aspect of the present disclosure may include a first bearing current bypass brush fixed relative to the first brush housing, the first bearing current bypass brush being positioned radially outward from the first brush. A first bearing current bypass slip ring is fixed relative to the first axial end of the rotor shaft and is located radially outward of the first slip ring. The first bearing current bypass brush is connected to electrical ground.

[0010] Another aspect of the present disclosure may be wherein the second brush extends circumferentially, and the second slip ring extends circumferentially, and the second brush is located radially outward from the second slip ring.

[0011] Another aspect of the present disclosure may be wherein the first slip ring and the second slip ring are located on the same axial side of the rotor shaft relative to the rotor core.

[0012] Another aspect of the disclosure may be where the wire gauge of the first electrical connector varies relative to the wire gauge of the second electrical connector.

[0013] Another aspect of the present disclosure may be wherein the second electrical connection includes a plurality of connections to a plurality of windings.

[0014] Another aspect of the present disclosure may be where one of the first or second electrical connectors is located near an exterior of the rotor shaft and the other of the first or second electrical connectors is located in an interior of the rotor shaft.

[0015] Another aspect of the present disclosure may include a first bearing current bypass brush fixed relative to the first brush housing, the first bearing current bypass brush being positioned radially outward from the first brush. A first bearing current bypass slip ring is fixed relative to the first axial end of the rotor shaft and is located radially outward of the first slip ring. The first bearing current bypass brush is configured to be connected to electrical ground.

[0016] Another aspect of the present disclosure may be wherein the rotor shaft includes an internal cooling passage, wherein the second brush is positioned radially outward and at least partially axially aligned with the first brush.The second slip ring is positioned axially outward and at least partially axially aligned with the second slip ring.

[0017] An electric motor is disclosed herein. The motor includes a stator having a plurality of stator windings and a rotor shaft supporting a rotor core surrounded by a plurality of rotor windings. A first brush is configured to engage a first slip ring fixed relative to a first distal end of the rotor shaft. The first brush includes one of a first conical protrusion or a first convex socket, and the first slip ring includes the other of the first conical protrusion or the first convex socket. A first electrical connector extends between the first slip ring and the plurality of rotor windings. A second brush is configured to engage a second slip ring when the second slip ring is fixed relative to the rotor shaft. A second electrical connector extends between the second slip ring and the plurality of rotor windings.

[0018] A vehicle is disclosed herein. The vehicle includes a body defining a passenger compartment and an electric motor supported in the body. The electric motor includes a stator having a plurality of stator windings and a rotor shaft supporting a rotor core surrounded by a plurality of rotor windings. A first brush is configured to engage a first slip ring fixed relative to a first distal end of the rotor shaft. The first brush includes one of a first conical protrusion or a first convex socket, and the first slip ring includes the other of the first conical protrusion or the first convex socket. A first electrical connector extends between the first slip ring and the plurality of rotor windings. A second brush is configured to engage a second slip ring when the second slip ring is fixed relative to the rotor shaft. A second electrical connector extends between the second slip ring and the plurality of rotor windings.

[0019] The present invention provides the following technical solutions.

[0020] Technical Solution 1. A rotor assembly for a motor, comprising:

[0021] Rotor shaft;

[0022] a rotor core supported by the rotor shaft and surrounded by a plurality of windings;

[0023] a first brush configured to engage a first slip ring fixed relative to a first distal end of the rotor shaft, wherein the first brush includes one of a first conical protrusion or a first convex socket and the first slip ring includes the other of the first conical protrusion or the first convex socket;

[0024] a first electrical connector extending between the first slip ring and the plurality of windings;

[0025] a second brush configured to engage the second slip ring when the second slip ring is fixed relative to the rotor shaft; and

[0026] A second electrical connector extends between the second slip ring and the plurality of windings.

[0027] Technical Solution 2. The assembly according to Technical Solution 1, wherein the first brush is located in a first brush housing, and the first brush is biased toward the first slip ring by a first spring element.

[0028] Technical Solution 3. A component according to Technical Solution 2, wherein the rotor shaft includes an internal passage having at least one internal conduit, and the at least one internal conduit is configured to receive at least one of the first electrical connector or the second electrical connector.

[0029] Technical Solution 4. A component according to Technical Solution 3, wherein the at least one internal conduit is made of a non-conductive material.

[0030] Technical Solution 5. A component according to Technical Solution 1, wherein at least one of the first electrical connector and the second electrical connector includes multiple connectors to the multiple windings.

[0031] Technical Solution 6. A component according to Technical Solution 1, wherein the second brush includes one of a second conical protrusion or a second convex socket, the one of the second conical protrusion or the second convex socket is configured to engage with the other of the second conical protrusion or the second convex socket on the second slip ring, and the second brush is located in a second brush housing, and the second brush is biased toward the second slip ring using a second spring element.

[0032] Technical Solution 7. The component according to Technical Solution 6 comprises: a first bearing current bypass brush, which is fixed relative to the first brush housing, wherein the first bearing current bypass brush is positioned radially outward from the first brush; and a first bearing current bypass slip ring, which is fixed relative to the first axial end of the rotor shaft and located radially outside the first slip ring, wherein the first bearing current bypass brush is connected to electrical grounding.

[0033] Technical Solution 8. A component according to Technical Solution 1, wherein the second brush extends circumferentially, and the second slip ring extends circumferentially, and the second brush is positioned radially outward from the second slip ring.

[0034] Technical Solution 9. An assembly according to Technical Solution 8, wherein the first slip ring and the second slip ring are located on the same axial side of the rotor shaft relative to the rotor core.

[0035] Technical Solution 10. An assembly according to Technical Solution 8, wherein the wire gauge of the first electrical connector changes relative to the wire gauge of the second electrical connector.

[0036] Technical Solution 11. A component according to Technical Solution 8, wherein the second electrical connection includes multiple connections to the multiple windings.

[0037] Technical Solution 12. A component according to Technical Solution 8, wherein one of the first or second electrical connectors is located near the outside of the rotor shaft, and the other of the first or second electrical connectors is located within the interior of the rotor shaft.

[0038] Technical Solution 13. The component according to Technical Solution 6 comprises: a first bearing current bypass brush, which is fixed relative to the first brush housing, wherein the first bearing current bypass brush is positioned radially outward from the first brush; and a first bearing current bypass slip ring, which is fixed relative to the first axial end of the rotor shaft and located radially outside the first slip ring, wherein the first bearing current bypass brush is configured to be connected to electrical ground.

[0039] Technical Solution 14. A component according to Technical Solution 1, wherein the rotor shaft includes an internal cooling passage, the second brush is positioned radially outward and at least partially axially aligned with the first brush, and the second slip ring is positioned axially outward and at least partially axially aligned with the second slip ring.

[0040] Technical Solution 15. A motor, comprising:

[0041] a stator having a plurality of stator windings;

[0042] a rotor shaft supporting a rotor core surrounded by a plurality of rotor windings;

[0043] a first brush configured to engage a first slip ring fixed relative to a first distal end of the rotor shaft, wherein the first brush includes one of a first conical protrusion or a first convex socket and the first slip ring includes the other of the first conical protrusion or the first convex socket;

[0044] a first electrical connector extending between the first slip ring and the plurality of rotor windings;

[0045] a second brush configured to engage the second slip ring when the second slip ring is fixed relative to the rotor shaft; and

[0046] A second electrical connection extends between the second slip ring and the plurality of rotor windings.

[0047] Technical Solution 16. An electric motor according to Technical Solution 15, wherein the second brush includes one of a second conical protrusion or a second convex socket, the one of the second conical protrusion or the second convex socket is configured to engage with the other of the second conical protrusion or the second convex socket on the second slip ring, and the second brush is located in a second brush housing, and the second brush is biased toward the second slip ring using a second spring element.

[0048] Technical Solution 17. The motor according to Technical Solution 16 includes: a first bearing current bypass brush, which is fixed relative to the first brush housing, wherein the first bearing current bypass brush is positioned radially outward from the first brush; and a first bearing current bypass slip ring, which is fixed relative to the first axial end of the rotor shaft and located radially outside the first slip ring, wherein the first bearing current bypass brush is connected to electrical grounding.

[0049] Technical Solution 18. An electric motor according to Technical Solution 15, wherein the second brush extends circumferentially, and the second slip ring extends circumferentially, and the second brush is positioned radially outward from the second slip ring.

[0050] Technical Solution 19. An electric motor according to Technical Solution 15, wherein the rotor shaft includes an internal cooling passage, the second brush is positioned radially outward and at least partially axially aligned with the first brush, and the second slip ring is positioned axially outward and at least partially axially aligned with the second slip ring.

[0051] Technical Solution 20. A means of transport, comprising:

[0052] a body defining a passenger compartment;

[0053] an electric motor supported in the body, the electric motor comprising:

[0054] a stator having a plurality of stator windings;

[0055] a rotor shaft supporting a rotor core surrounded by a plurality of rotor windings;

[0056] a first brush configured to engage a first slip ring fixed relative to a first distal end of the rotor shaft, wherein the first brush includes one of a first conical protrusion or a first convex socket and the first slip ring includes the other of the first conical protrusion or the first convex socket;

[0057] a first electrical connector extending between the first slip ring and the plurality of rotor windings;

[0058] A second brush configured to engage the second slip ring when the second slip ring is fixed relative to the rotor shaft; and a second electrical connector extending between the second slip ring and the plurality of rotor windings. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] One or more embodiments will now be described by way of example with reference to the accompanying drawings, in which:

[0060] Figure 1 A vehicle is illustrated schematically.

[0061] Figure 2 Schematic diagram of the bonding to Figure 1 A cross-sectional view of an electric motor in a vehicle.

[0062] Figure 3 The diagram shows Figure 2 An enlarged view of an example brush assembly with an example slip ring on a rotor shaft of an electric motor.

[0063] Figure 4 yes Figure 2 A cross-sectional view of the brush assembly shown in FIG.

[0064] Figure 5 A perspective view of a portion of an electrical conduit is shown.

[0065] Figure 6 Another example rotor assembly is schematically illustrated.

[0066] Figure 7 Yet another example rotor assembly is schematically illustrated.

[0067] Figure 8 Yet another example rotor assembly is schematically illustrated.

[0068] Fig. 9 Yet another example rotor assembly is schematically illustrated.

[0069] Fig.10 Yet another example rotor assembly is schematically illustrated.

[0070] Fig.11 Yet another example rotor assembly is schematically illustrated.

[0071] Fig.12 Yet another example rotor assembly is schematically illustrated. DETAILED DESCRIPTION

[0072] The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0073] According to a non-limiting example, a vehicle Figure 1 The vehicle 10 is generally indicated at 10. The vehicle 10 includes a body 12 supported on a plurality of wheels 16. One or more of the plurality of wheels 16 are steerable. The body 12 partially defines a passenger compartment 20 having a seat 23 positioned behind an instrument panel 26. A steering controller 30 is disposed between the seat 23 and the instrument panel 26. The steering controller 30 is operated to control the orientation of the steerable wheel(s).

[0074] The vehicle 10 includes an electric machine, such as an electric motor 34, connected to a transmission 36 that provides power to one or more of the plurality of wheels 16. A rechargeable energy storage system (RESS) 38 is disposed in the body 12 and provides power to the electric motor 34. At this point, it should be appreciated that the location of the electric motor 34, the transmission 36, and the RESS 38 in the body 12 may vary.

[0075] Figure 2 Picture shows Figure 1 5. A cross-sectional view of an electric motor 34 is shown. In the illustrated example, the electric motor 34 includes a housing 52 that at least partially encloses a stator 54 and a rotor assembly 57. The rotor assembly 57 includes at least a rotor core 58 that is secured to a rotor shaft 56 with a plurality of windings 60. The plurality of windings 60 are energized by first and second brush assemblies 62 located on opposite axial ends of the rotor shaft 56. The stator 54 includes a plurality of windings 55 for generating an electric field to induce rotation of the rotor shaft 56. A gear 66 may be attached to the rotor shaft 56 to provide an output for the electric motor 34.

[0076] In the illustrated example, electric motor 34 is a singly excited electric motor having a plurality of windings 60 through which current flows to generate a magnetic field and induce rotation of rotor shaft 56 relative to stator 54. One feature of electric motor 34 being a singly excited motor is the ability to minimize electrical losses by controlling the magnetic fields in the plurality of windings during operation.

[0077] like Figures 2 to 3 As shown in FIG. 1 , the rotor shaft 56 includes an internal passage 70 for receiving an electrical conduit 72 comprised of a non-conductive material. The electrical conduit 72 includes at least a portion of a first electrical connector 74 extending between the first brush assembly 62 and the plurality of windings 60 and a second electrical connector 76 extending between the second brush assembly 62 and the plurality of windings 60. In the illustrated example, the first electrical connector 74 and the second electrical connector 76 have opposite polarities, such as the first electrical connector 74 having a positive charge and the second electrical connector 76 having a negative charge.

[0078] like Figures 2 to 4 As shown in FIG, the first and second brush assemblies 62 each include a brush housing 80 that at least partially encloses a brush 82 for engaging a slip ring 84 and is fixed to prevent rotation relative to the rotor shaft 56. In the illustrated example, the brush 82 includes a protrusion 86 having a conical distal end 88 that extends through a central brush opening 81 in the brush housing 80 to engage a male socket 89 on the slip ring 84. One feature of the conical distal end 88 engaging the male socket 89 is increased surface contact between the brush 82 and the slip ring 84 for forming an electrical connection.

[0079] The brush 82 is biased toward the slip ring 84 by a biasing element 92, such as a spring or elastomer. The brush 82 is keyed relative to the brush housing 80 to prevent the brush 82 from rotating relative to the brush housing 80. In the illustrated example, the keyed connection includes a flat or protrusion 83 on the brush 82 that mates with a corresponding flat or protrusion 85 on the brush housing 80.

[0080] Because the brush 82 is biased and can move through the brush housing 80 along the central longitudinal axis, the extendable connector 93 extends from the electrical connector 94 and the brush 82 in the electrical connector 95 to maintain electrical connection when the brush 82 moves in the brush housing 80. The extendable connector 93 may include a wire of sufficient length to engage both the brush 82 and the electrical connector 94 throughout the travel of the brush 82. The extendable connector 93 may be fixed to both the brush 82 and the electrical connector 94. Alternatively, the extendable connector 93 may be fixed to only one of the brush 82 or the electrical connector 94 and biased against the other of the brush 82 or the electrical connector 94.

[0081] The seal 90 is located near the brush opening 81 and is fixed relative to the brush housing 80. The seal 90 is configured to slidably engage at least one of the rotor shaft 56 or the electrical conduit 72 to form a seal. In the illustrated example, the seal 90 extends circumferentially to form a complete ring to prevent debris or lubricant from entering the connection between the brush 82 and the slip ring 84. The seal 90 includes a base portion 90B that engages the brush housing 80 on a radially outer side relative to the central longitudinal axis of the brush opening 81. The flange 90F extends radially inward from the base portion 90B of the seal 90 and is composed of a polymer such as rubber.

[0082] like Figure 3 and Figure 5 As shown in the drawings, the first electrical connector 74 and the second electrical connector 76 extend radially from the electrical conduit 72 at one of the plurality of first joints 98A or the second joints 98B, respectively, to form electrical connections with the plurality of windings 60. The first electrical connector 74 and the second electrical connector 76 may each include a plurality of connections with the plurality of windings 60 through a corresponding one of the plurality of first joints 98A and the second joints 98B. The electrical conduit 72 includes at least one tab 72T and a stop surface 72S that interfaces with the rotor shaft 56 to help prevent the electrical conduit 72 from moving relative to the rotor shaft 56, thereby aligning the first joint 98A and the second joint 98B with the openings in the rotor shaft 56 to connect with the plurality of windings 60.

[0083] One feature of having multiple connections between the first and second electrical connections 74, 76 and the plurality of windings 60 is increased reliability. In particular, if one of the multiple connections fails, the multiple connections ensure that the plurality of windings 60 remain in contact with the first and second electrical connections 74, 76. Figures 2 to 3 As shown in FIG. 1 , a first jumper wire 100A extends from a corresponding one of the first connectors 98A to the plurality of windings, and a second jumper wire 100B extends between the second connector 98B and the plurality of windings 60 .

[0084] like Figure 3 and Figure 5 As shown in the figure, when the first jumper 100A and the second jumper 100B are inserted into the rotor shaft 56 and the corresponding first joints 98A and second joints 98B in the electrical conduit 72, the first electrical connector 74 and the second electrical connector 76 are each connected to the first jumper 100A and the second jumper 100B respectively through a connection such as a snap connection.

[0085] In addition, the lengths of the first and second electrical connectors 74, 76 may vary due to packaging limitations. To compensate for such length variations, the first electrical connector 74 may include wires of different gauges than the second electrical connector 76 to compensate for variations in internal resistance that may occur due to different lengths.

[0086] Figure 6 Another example rotor assembly 57-2 is schematically illustrated. The rotor assembly 57-2 is similar to the rotor assembly 57 except as shown in the figures or described below. The rotor assembly 57-2 includes a rotor shaft 56-2 having an internal passage 70-2 for receiving a first electrical connector 74-2 and a second electrical connector 76-2. The internal passage 70-2 can be continuous or discontinuous.

[0087] The first electrical connector 74-2 connects the plurality of windings 60-2 around the rotor core 58-2 to the brush assembly 62-2. The brush assembly 62-2 includes a brush housing 80-2 at least partially surrounding brushes 82-2 for engaging slip rings 84-2 that are fixed to rotation relative to the rotor shaft 56-2.

[0088] The second electrical connector 76-2 connects the radial brush assembly 110-2 to the plurality of windings 60-2. In the illustrated example, the radial brush assembly 110-2 is positioned radially outward from the radial slip ring 112-2 and includes a radial brush 113-2 fixed relative to the brush housing 114-2. The radial slip ring 112-2 also includes at least one radial connector 115-2 to connect with the second electrical connector 76-2.

[0089] In addition, the first electrical connector 74-2 and the second electrical connector 76-2 include one or more jumpers 100A-2, 100B-2 extending between the plurality of windings 60-2 and the first electrical connector 74-2 and the second electrical connector 76-2, respectively. The first electrical connector 74-2 and the second electrical connector 76-2 can be equal in axial length because the radial brush assembly 110-2 is used with a radial slip ring 112-2 fixed relative to the rotor shaft 56-2 and electrically connected to the plurality of windings 60-2. For simplicity, the internal conduit is not illustrated with the first electrical connector 74-2 and the second electrical connector 76-2.

[0090] Figure 7 Another example rotor assembly 57-3 is schematically illustrated. The rotor assembly 57-3 is similar to the rotor assembly 57 except as shown in the drawings or described below. The rotor assembly 57-3 includes a rotor shaft 56-3 having an internal passage 70-3 for receiving a first electrical connector 74-3 and a second electrical connector 76-3. In the illustrated example, the first and second electrical connectors overlap each other relative to the central longitudinal axis of the rotor shaft 56-3.

[0091] The first electrical connector 74-3 connects the plurality of windings 60-3 around the rotor core 58-3 to the brush assembly 62-3. The brush assembly 62-3 includes a brush housing 80-3 at least partially surrounding brushes 82-3 for engaging a slip ring 84-3 fixed to non-rotation relative to the rotor shaft 56-3.

[0092] The second electrical connector 76-3 connects the radial brush assembly 110-3 to the plurality of windings 60-3. In the illustrated example, the radial brush assembly 110-3 is positioned radially outward from the radial slip ring 112-3 and includes a radial brush 113-3 fixed relative to the brush housing 114-3. The radial slip ring 112-3 also includes at least one radial connector 115-3 to connect with the second electrical connector 76-3.

[0093] Additionally, the first and second electrical connectors 74 - 3 , 76 - 3 may include one or more jumpers 100A- 3 , 100B- 3 extending between the plurality of windings 60 - 3 and the first and second electrical connectors 74 - 3 , 76 - 3 , respectively.

[0094] In addition, the first electrical connector 74-3 and the second electrical connector 76-3 include varying axial lengths because the radial brush assembly 110-3 is used with a radial slip ring 112-3 fixed relative to the rotor shaft 56 on the same axial side of multiple windings. Therefore, the gauge of the wire used for the first electrical connector 74-3 and the second electrical connector 76-3 varies to accommodate the varying internal resistance. For simplicity, the internal conduit is not illustrated with the first electrical connector 74-3 and the second electrical connector 76-3.

[0095] Figure 8 Another example rotor assembly 57-4 is schematically illustrated. The rotor assembly 57-4 is similar to the rotor assembly 57 except as shown in the figures or described below. The rotor assembly 57-4 includes a rotor shaft 56-4 having an internal passage 70-4 for receiving a first electrical connector 74-4 and at least one external groove for receiving a second electrical connector 76-4. In the illustrated example, the first and second electrical connectors overlap each other relative to the central longitudinal axis of the rotor shaft 56-4.

[0096] The first electrical connector 74-4 connects the plurality of windings 60-4 around the rotor core 58-4 to the brush assembly 62-4. The brush assembly 62-4 includes a brush housing 80-4 at least partially surrounding brushes 82-4 for engaging a slip ring 84-3 fixed to non-rotation relative to the rotor shaft 56-4.

[0097] The second electrical connector 76-4 connects the radial brush assembly 110-4 to the plurality of windings 60-4. In the illustrated example, the radial brush assembly 110-3 is positioned radially outward from the radial slip ring 112-4 and includes radial brushes 113-4 fixed relative to the brush housing 114-4. The radial slip ring 112-4 also includes at least one radial connector 115-4 to connect with the second electrical connector 76-4.

[0098] In addition, the first electrical connector 74-4 may include one or more jumper wires 100A-4 extending between the plurality of windings 60-4 and the first electrical connector 74-4. The first electrical connector 74-4 and the second electrical connector 76-4 include varying axial lengths due to the radial brush assembly 110-4 being used with a radial slip ring 112-4 fixed relative to the rotor shaft 56 on the same axial side of the plurality of windings. Therefore, the gauge of the wire used for the first electrical connector 74-4 and the second electrical connector 76-4 varies to accommodate the varying internal resistance. For simplicity, the internal conduit is not illustrated with the first electrical connector 74-4 and the second electrical connector 76-4.

[0099] In addition, a bearing 85-4, such as a roller bearing or a ball bearing, may be located between the rotor shaft 56-4 and the brush housing 80-4 to mitigate bearing currents. In particular, the bearing 85-4 may include a conductive grease to facilitate grounding the rotor shaft 56-4 relative to the ground line 120-4 through the brush housing 80-4. One feature of utilizing the bearing 85-4 is reduced friction when compared to a sliding connection.

[0100] Fig. 9 Another example rotor assembly 57-5 is schematically illustrated. The rotor assembly 57-5 is similar to the rotor assembly 57 except as shown in the figures or described below. The rotor assembly 57-5 includes a rotor shaft 56-5 having internal passages 70A-5 and 70B-5 for receiving a first electrical connector 74-5 and a second electrical connector 76-5, respectively.

[0101] The first electrical connector 74-5 connects the plurality of windings 60-5 around the rotor core 58-5 to the brush assembly 62-5 on the first axial end of the rotor shaft 56-5. In the illustrated example, at least a portion of the first electrical connector 74-6 is located near the exterior of the rotor shaft 56-5.

[0102] The brush assembly 62-5 includes a brush housing 80-5 that at least partially surrounds a brush 82-5 for engaging a slip ring 84-5 that is fixed and non-rotating relative to the rotor shaft 56-5. The brush assembly 62-5 also includes a bearing current bypass brush 118-5 positioned radially outward from the brush 82-5. The bearing current bypass slip ring 116-5 is positioned radially outward from the slip ring 84-5 for engaging the bearing current bypass brush 118-5. The bearing current bypass brush 118-5 is attached to the brush housing 80-5 and connected to an electrical ground 120-5. The bearing current bypass brush 118-5 grounds the rotor shaft 56-5 to allow the circulating current to be grounded, thereby reducing pitting and groove corrosion of the bearing 122-5. The brush 118-5 provides a minimum resistance path that does not include the bearing 122-5. In addition, the brush 118-5 may include multiple brushes at each axial end to improve grounding.

[0103] The second electrical connector 76-5 connects the plurality of windings 60-5 through another brush assembly 62-5 on the second axial end of the rotor shaft 56-5. In the illustrated example, the second electrical connector 76-5 is located in the internal passage 70A-5.

[0104] In the illustrated example, since the rotor core 58-5 is spaced apart from the axial center of the rotor shaft 56-5, the first electrical connector 74-5 and the second electrical connector 76-5 include different axial lengths. Therefore, the gauge of the wires used for the first electrical connector 74-5 and the second electrical connector 76-5 varies to accommodate the varying internal resistance. For simplicity, the internal conduit is not illustrated with the first electrical connector 74-5 or the second electrical connector 76-5.

[0105] Fig.10 Another example rotor assembly 57-6 is schematically illustrated. The rotor assembly 57-6 is similar to the rotor assembly 57 except as shown in the drawings or described below. The rotor assembly 57-6 includes a rotor shaft 56-6 having a first electrical connector 74-6 and a second electrical connector 76-6 in electrical communication with a plurality of windings 60-6 on a rotor core 58-6 fixed relative to the rotor shaft 56-6. For simplicity, the internal conduit is not illustrated with the first electrical connector 74-6 or the second electrical connector 76-6.

[0106] In the illustrated example, at least a portion of the first electrical connector 74-6 is located near the exterior of the rotor shaft 56-6 for connecting the first radial brush assembly 110-6 with the plurality of windings 60-6. The radial brush assembly 110-6 is located radially outward from the radial slip ring 112-6 and includes radial brushes 113-6 fixed relative to the brush housing 114-6. The jumper 100A-6 connects the first electrical connector 74-6 and the plurality of windings 60-6.

[0107] The brush assembly 62-6 includes a brush housing 80-6 that at least partially surrounds a brush 82-6 for engaging a slip ring 84-5 that is fixed and non-rotating relative to the rotor shaft 56-6. The brush assembly 62-6 also includes a bearing current bypass brush 118-6 positioned radially outward from the brush 82-6. The bearing current bypass slip ring 116-6 is positioned radially outward from the slip ring 84-6 for engaging the bearing current bypass brush 118-6. The bearing current bypass brush 118-6 is attached to the brush housing 80-6 and connected to an electrical ground 120-6. The bearing current bypass brush 118-6 grounds the rotor shaft 56-6 to allow the circulating current to be grounded, thereby reducing pitting and groove corrosion of the bearing 122-6. The brush 118-6 provides a minimum resistance path that does not include the bearing 122-6. In addition, the brush 118-6 may include multiple brushes at each axial end to improve grounding.

[0108] The radial brush assembly 110-6 also includes a radial outer bearing current bypass brush 124-6 that is axially aligned with a bearing current bypass slip ring 126-6 fixed relative to the rotor shaft 56-6. The bearing current bypass brush 124-6 is in electrical communication with the electrical ground 120-6 to ground the rotor shaft 56-6. This provides a minimum resistance path that does not include the bearing 122-6.

[0109] The second electrical connector 76-6 connects the plurality of windings 60-6 around the rotor core 58-6 to the brush assembly 62-5. The rotor shaft 56-6 includes an internal passage 70-6 for receiving the second electrical connector 76-6 connecting the brush assembly 62-6 to the plurality of windings 60-6.

[0110] Fig.11 Another example rotor assembly 57-7 is schematically illustrated. The rotor assembly 57-7 is similar to the rotor assembly 57-7 except where shown in the drawings or described below. The rotor assembly 57-7 includes a rotor shaft 56-7 having a first electrical connector 74-7 and a second electrical connector 76-7 in electrical communication with a plurality of windings 60-7 around a rotor core 58-7 fixed relative to the rotor shaft 56-7. For simplicity, the internal conduit is not illustrated with the first electrical connector 74-7 or the second electrical connector 76-7.

[0111] In the illustrated example, the second electrical connector 76-7 connects the radial brush assembly 110-7 with the plurality of windings 60-7. The rotor shaft 56-7 includes an internal passage 70B-7 for receiving the second electrical connector 76-7 connecting the radial brush assembly 110-7 with the plurality of windings 60-7.

[0112] The radial brush assembly 110-7 is positioned radially outward from the radial slip ring 112-7 and includes radial brushes 113-7 fixed relative to the brush housing 114-7. The radial slip ring 112-7 also includes at least one radial connector 115-7 connected to the second electrical connector 76-7.

[0113] The radial brush assembly 110-7 also includes a radial outer bearing current bypass brush 124-7 that is axially aligned with a bearing current bypass slip ring 126-7 fixed relative to the rotor shaft 56-7. The bearing current bypass brush 124-7 is in electrical communication with the electrical ground 120-7 to ground the rotor shaft 56-7. This provides a path of least resistance that avoids the bearing 122-7.

[0114] The brush assembly 62-7 includes a brush housing 80-7 that at least partially surrounds a brush 82-7 for engaging a slip ring 84-7 that is fixed and non-rotating relative to the rotor shaft 56-7. The brush assembly 62-7 also includes a bearing current bypass brush 118-7 positioned radially outward from the brush 82-7. The bearing current bypass slip ring 116-7 is positioned radially outward from the slip ring 84-7 for engaging the bearing current bypass brush 118-7. The bearing current bypass brush 118-7 is attached to the brush housing 80-6 and connected to an electrical ground 120-7. The bearing current bypass brush 118-7 grounds the rotor shaft 56-7 to allow the circulating current to be grounded, thereby reducing pitting and groove corrosion of the bearing 122-7. The brush 118-7 provides a minimum resistance path that does not include the bearing 122-7. In addition, the brush 118-7 may include multiple brushes at each axial end to improve grounding.

[0115] Fig.12 Another example rotor assembly 57-8 is schematically illustrated. The rotor assembly 57-8 is similar to the rotor assembly 57 except as shown in the drawings or described below. The rotor assembly 57-8 includes a rotor shaft 56-8 having a first electrical connector 74-8 and a second electrical connector 76-8 in electrical communication with a plurality of windings 60-8 on a rotor core 58-8 fixed relative to the rotor shaft 56-8. For simplicity, internal conduits for the first electrical connector 74-8 or the second electrical connector 76-8 are not illustrated.

[0116] In the illustrated example, a first electrical connector 74-8 extends along the internal passage 70A-8 and connects to a brush assembly 62-8 and at least one jumper 100A-8 with a plurality of windings 60-8 around the rotor core 58-8. A second electrical connector 76-8 extends through another passage 70B-8 through the rotor shaft 56-8 and connects the plurality of windings 60-8 to the brush assembly 62-8 via at least one jumper 100B-8.

[0117] In the illustrated example, the brush assembly 62-8 includes a brush housing 80-8 at least partially surrounding a first brush 82-8 for engaging a first slip ring 84-8 fixed to non-rotation relative to the rotor shaft 56-8. The first brush 82-8 and the first slip ring 84-8 are in electrical communication with the first electrical connector 74-8.

[0118] The brush assembly 62-8 also includes a second brush 132-8 for engaging a second slip ring 130-8 located on the rotor shaft 56-8. The second brush 132-8 and the second slip ring 130-8 are in electrical communication with the second electrical connector 76-8. The first brush 82-8 and the slip ring 84-8 are positioned radially inwardly from the second brush 132-8 and the slip ring 132-8, respectively.

[0119] The rotor assembly 57-8 also includes a bearing current brush assembly 136-8. In the illustrated example, the bearing current brush assembly 136-8 includes at least one bearing current brush 138-8 fixed relative to the bearing current brush housing 140-8. At least one bearing current brush 138-8 engages with a bearing current slip ring 142-8 fixed relative to the rotor shaft 56-8. The bearing current bypass brush 138-8 grounds the rotor shaft 56-8 to allow circulating current to bypass the bearing 122-8, thereby reducing pitting and groove corrosion of the bearing 122-8.

[0120] In addition, the rotor shaft 56-8 includes an internal cooling passage 134-8 for cooling the rotor shaft during operation. In the illustrated example, the internal cooling passage 134-8 is in the rotor shaft. The internal cooling passage 134-8 extends through a central region of the current bearing brush housing 140-8 and is positioned radially inward from at least one bearing current brush 138-8 and at least one bearing current slip ring 142-8.

[0121] The terms "a" and "an" do not indicate a limitation of quantity, but rather indicate the presence of at least one of the referenced item. The term "or" means "and / or" unless the context clearly indicates otherwise. References to "aspects" throughout the specification mean that a particular element (e.g., feature, structure, step, or characteristic) described in conjunction with that aspect is included in at least one aspect described herein, and may or may not be present in other aspects. In addition, it should be understood that the described elements may be combined in a suitable manner in the various aspects.

[0122] When an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present.

[0123] Although the above disclosure has been described with reference to exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made without departing from its scope, and that its elements may be replaced with equivalents. In addition, many modifications may be made to adapt specific situations or materials to the teachings of the present disclosure without departing from the scope of the present disclosure. Therefore, it is intended that the present disclosure is not limited to the specific embodiments disclosed, but will include embodiments that fall within its scope.

Claims

1. A rotor assembly for an electric motor, comprising: Rotor shaft; a rotor core supported by the rotor shaft and surrounded by a plurality of windings; a first brush configured to engage a first slip ring fixed relative to a first distal end of the rotor shaft, wherein the first brush includes one of a first conical protrusion or a first convex socket and the first slip ring includes the other of the first conical protrusion or the first convex socket; a first electrical connector extending between the first slip ring and the plurality of windings; a second brush configured to engage the second slip ring when the second slip ring is fixed relative to the rotor shaft; and A second electrical connector extends between the second slip ring and the plurality of windings.

2. The assembly according to claim 1, wherein The first brush is located in a first brush housing, and the first brush is biased toward the first slip ring using a first spring element.

3. The assembly according to claim 2, wherein: The rotor shaft includes an internal passage having at least one internal conduit configured to receive at least one of the first electrical connector or the second electrical connector.

4. The assembly according to claim 3, wherein: The at least one inner conduit is constructed of a non-conductive material.

5. The assembly according to claim 1, wherein: At least one of the first electrical connector and the second electrical connector includes a plurality of connections to the plurality of windings.

6. The assembly according to claim 1, wherein: The second brush includes one of a second conical protrusion or a second convex socket, the one of the second conical protrusion or the second convex socket is configured to engage the other of the second conical protrusion or the second convex socket on the second slip ring, and the second brush is located in a second brush housing, and the second brush is biased toward the second slip ring using a second spring element.

7. The assembly according to claim 6, comprising: a first bearing current bypass brush fixed relative to the first brush housing, wherein the first bearing current bypass brush is positioned radially outward from the first brush; and a first bearing current bypass slip ring fixed relative to the first axial end of the rotor shaft and located radially outward of the first slip ring, wherein the first bearing current bypass brush is connected to electrical ground.

8. The assembly of claim 1, wherein: The second brush extends circumferentially, and the second slip ring extends circumferentially, and the second brush is located radially outward from the second slip ring.

9. A motor, comprising: a stator having a plurality of stator windings; a rotor shaft supporting a rotor core surrounded by a plurality of rotor windings; a first brush configured to engage a first slip ring fixed relative to a first distal end of the rotor shaft, wherein the first brush includes one of a first conical protrusion or a first convex socket and the first slip ring includes the other of the first conical protrusion or the first convex socket; a first electrical connector extending between the first slip ring and the plurality of rotor windings; a second brush configured to engage the second slip ring when the second slip ring is fixed relative to the rotor shaft; and A second electrical connection extends between the second slip ring and the plurality of rotor windings.

10. A means of transport, comprising: a body defining a passenger compartment; an electric motor supported in the body, the electric motor comprising: a stator having a plurality of stator windings; a rotor shaft supporting a rotor core surrounded by a plurality of rotor windings; a first brush configured to engage a first slip ring fixed relative to a first distal end of the rotor shaft, wherein the first brush includes one of a first conical protrusion or a first convex socket and the first slip ring includes the other of the first conical protrusion or the first convex socket; a first electrical connector extending between the first slip ring and the plurality of rotor windings; a second brush configured to engage the second slip ring when the second slip ring is fixed relative to the rotor shaft; and A second electrical connection extends between the second slip ring and the plurality of rotor windings.

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