System and method for rotor shaft grounding

Abstract

The present disclosure provides systems and methods for rotor shaft grounding. Methods and systems for grounding a rotor of an electric machine. The motor system includes: a rotor shaft; a ground cap coupled to an end portion of the rotor shaft; and a cam aligned with an axis of rotation of the rotor shaft and electrically coupled to the grounded cap. The motor system also includes an end plate of the housing and a spring extending between the cam and an inner surface of the housing, where the ground cover, the cam, and the spring are electrically conductive.

Description

Technical Field

[0001] The present description generally relates to methods and systems for grounding a rotor shaft of an electric machine. Background Art

[0002] Some previous electric motors, such as traction motors, apply electrical current to components such as rotor bearings. This current discharge can potentially cause electrical pitting of the rotor bearings, thereby shortening the life of the motor.

[0003] Attempts have been made to ground the rotor of an electric motor. Shiraishi shows an exemplary approach in US 4,515,417A in which contactors are used to attempt to reduce electrolytic corrosion of the bearings. The contactors are radially aligned and retracted during motor operation. However, the inventors herein have recognized problems that may exist with Shiraishi's system and other grounding systems. The contactors in the motor may be susceptible to degradation. In addition, the inventors have recognized that it may be desirable to be able to discharge current from the rotor during motor operation. Brushes used in other grounding devices may also be susceptible to undesirable degradation. Summary of the invention

[0004] In one example, the above problems can be at least partially solved by a motor system, the motor system comprising: a rotor shaft; a ground cover, the ground cover is coupled to the end of the rotor shaft; and a cam, the cam is aligned with the rotation axis of the rotor shaft and electrically coupled to the ground cover. The alignment of the cam with the rotation axis of the rotor shaft reduces the degradation of the cam and / or the ground cover caused by the relative movement between the cam and the ground cover. The motor system also includes an end plate of the housing and a spring, the spring extending between the cam and the inner surface of the housing, wherein the ground cover, the cam and the spring are conductive. Therefore, the ground cover, the cam and the spring create a path for the current to discharge from the rotor to the housing, thereby reducing (e.g., in some cases eliminating) the amount of current discharged through the bearings of the motor during the operation of the machine in which the rotor rotates. Therefore, the life of the bearing is increased. In addition, the spring is used to make the cam self-centering, thereby reducing the relative movement of the cam relative to the ground cover, thereby reducing the wear in the grounding system, especially the cam. Therefore, the life of the machine is further increased. Additionally, using a cam in a grounding system may increase the life of the system compared to a grounding assembly utilizing brushes.

[0005] It will be understood that the above summary is provided to introduce a series of concepts further described in the detailed description in a simplified form. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims following the detailed description. Furthermore, the claimed subject matter is not limited to embodiments that address any disadvantages mentioned above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 A vehicle including an electric powertrain is shown.

[0007] Figure 2 An electric machine including a rotor and a grounding system is shown.

[0008] Figure 3 Shows Figure 2 Detailed view of the rotor and grounding system.

[0009] Figure 4 A method for assembling a grounding system on a rotor of an electric machine is shown. DETAILED DESCRIPTION

[0010] The following description relates to a system and method for grounding the rotor of an electric motor. When in use, the electric motor applies current in the rotor, which may cause arc pitting, electromagnetic interference and / or electromagnetic compatibility challenges. In order to overcome these challenges, a grounding system is used to discharge the current from the rotor to the housing of the electric motor. The grounding system includes a grounding cover, a grounding cam and a grounding spring, each of which is aligned with the axis of rotation of the rotor. Therefore, during operation of the machine, the grounding cam and the grounding cover experience a reduced amount of movement relative to each other. In this way, the grounding system is able to discharge current from the rotor while reducing wear on the components of the grounding system. Specifically, the use of a cam in a grounding system can reduce wear between the cam and the grounding cover due to the reduction in friction compared to a grounding brush.

[0011] In some examples, the electric machine may be included in a vehicle, such as Figure 1 Thus, the motor can provide power to one or more drive wheels of the vehicle and / or provide mechanical power to other suitable vehicle components. Figure 2 and Figure 3 As shown, the grounding cover can be located at the end of the rotor shaft of the motor. In addition, the grounding cam can be kept in coplanar contact with the grounding cover by the force applied by the grounding spring. Figure 4 A method for installing a grounding system into an electric machine is shown in FIG.

[0012] Figures 1 to 3A coordinate system is included for orienting the view. In one example, the y-axis can be a vertical axis (e.g., parallel to the gravity axis), the z-axis can be a longitudinal axis (e.g., a horizontal axis), and / or the x-axis can be a transverse axis. However, in other examples, the axes can have other orientations. In addition, in addition to the schematically depicted components, Figure 2 and Figure 3 However, in alternative examples, the components in the electric machine may have other suitable relative sizes.

[0013] Figure 1 A schematic representation of a vehicle 100 having an electric machine 114 is shown, which may be included in a powertrain 101. In such an example, the electric machine 114 may be a traction motor, and thus the vehicle may be an electric vehicle (EV). Additionally or alternatively, the electric machine 114 may be used to provide mechanical power to other suitable vehicle components, or may be used in other suitable systems, such as manufacturing systems, appliances, industrial systems, etc. In the EV example, the EV may be specifically a pure electric vehicle in one example, or may be a hybrid electric vehicle (HEV) including an internal combustion engine 112 in another example. Various HEV architectures may be used, such as an HEV architecture in which the electric machine provides mechanical power to one axle and the engine provides mechanical power to another axle, an HEV architecture in which the engine is used only to recharge the energy storage device 120, an HEV architecture in which the engine and the motor are connected in series or in parallel, and the like.

[0014] The transmission system 101 may include a transmission 108 (e.g., a gearbox, a gear train, etc.) coupled to one or more of the axles 104 of the vehicle 100. However, in alternative examples, the transmission may be omitted from the vehicle, and the motor 114 and / or additional motors may provide mechanical power directly to the drive wheels. Figure 1 The transmission 108 may be rotationally coupled to one of the axles 104 as shown, or to the other axle or both axles in other examples. The transmission 108 may transfer mechanical power from the motor 114 and / or another suitable prime mover to the axles 104 and then to the wheels 102 to propel the vehicle 100 .

[0015] In some examples, electric machine 114 may be a motor-generator having the ability to convert electrical energy into mechanical energy and vice versa. Electric machine 114 may be electrically coupled to an energy storage device 120 (e.g., a battery such as a traction battery, a capacitor, a combination thereof, etc.) of vehicle 100 to both draw power from the energy storage device and provide electrical energy for storage at the energy storage device in different operating modes.

[0016] Can be based on Figure 1The vehicle control system 124 is shown to include a controller 126 to perform adjustments of the vehicle (e.g., powertrain) between various modes and control of operation within each mode. The controller 126 can be a microcomputer that includes elements such as a microprocessor unit, input / output ports, electronic storage media (e.g., read-only memory chips, random access memory, keep-alive memory) for executable programs and calibration values, and a data bus. The storage medium can be programmed with computer-readable data representing instructions (e.g., computer-readable instructions) that can be executed by a processor to perform the methods described below as well as other variations that are anticipated but not specifically listed.

[0017] The controller 126 may receive various signals from sensors 128 coupled to various areas of the vehicle 100. For example, the sensors 128 may include sensors at the motor 114 for measuring motor speed and motor temperature, pedal position sensors for detecting depression of an operator-actuated pedal (such as a control pedal), speed sensors at the wheels 102, etc. Figure 1 After receiving the signals from the various sensors 128, the controller 126 processes the received signals and uses the various actuators 130 of the vehicle 100 to adjust the vehicle operation based on the received signals and the computer-readable instructions stored on the memory of the controller 126. For example, the controller 126 can receive an indication of a pedal being depressed, thereby signaling a desire to increase the vehicle speed. In response, the controller 126 can command an increase in the speed of the motor 114. In addition, the controller 126 can command the motor 114 to operate as a generator to recharge the energy storage device 120.

[0018] Figure 2 An electric machine 200 is shown in cross section and may be Figure 1 Thus, in some examples, the motor 200 can provide power to a transmission of a vehicle. In other examples, as described above, the motor 200 can be included in another suitable system. Figure 2 as well as Figure 3 The cutting plane of the cross-sectional view depicted in extends through the rotation axis 206 of the electric machine.

[0019] like Figure 2 As shown, the motor 200 includes a rotor 203 having a rotor shaft 204 and a stator 205. The stator 205 generates a magnetic field (e.g., a rotating magnetic field) that acts on the rotor 203 and causes the rotor shaft 204 to rotate within the motor 200 during a motor operation mode in which the motor generates a rotational output. The rotor shaft 204 rotates around an axis of rotation 206, which may be referred to as a central axis. The axis of rotation 206 is the longitudinal axis of the rotor 203 and may be parallel to the z-axis.

[0020] The rotor shaft 204 may include a shaft extension 218 that extends outwardly along the z-axis. The motor 200 may also include a bearing cavity 220 having the bearing 214 therein. The bearing cavity 220 may specifically be a wet cavity and in such examples include a fluid contained therein and / or circulated therethrough, such as oil in some examples. It should be understood that another bearing may be coupled to the opposite end of the rotor shaft 204.

[0021] In addition, the shaft extension 218 contacts the bearing 214, and specifically contacts the inner race 213 of the bearing. The outer race 260 of the bearing 214 can contact a section 262 (e.g., a stepped section) of the end plate 212 of the housing 202. The housing 202 can form a housing for the stator 205 and the rotor 203. In detail, the end plate 212 can be coupled to the housing body 264. In addition, the end plate 212 can form at least a portion of an end winding cavity 266, which can have a stator end winding 268 located therein. In one example, the end winding cavity 266 can be in fluid communication with the bearing cavity 220. Alternatively, in another example, the end winding cavity 266 can be fluidly separated from the bearing cavity 220.

[0022] In the example shown, the bearing 214 is a ball bearing. However, in other examples, another suitable bearing may be used, such as a roller bearing, a thrust bearing, a combination thereof, etc. The bearing 214 may be positioned adjacent to the end 215 of the rotor shaft 204. In addition, the bearing 214 supports the rotation of the rotor shaft 204 around the rotation axis 206. Therefore, when the rotor shaft 204 rotates, the shaft extension 218 rotates around the rotation axis 206 within the bearing cavity 220.

[0023] The rotor shaft 204 includes a shaft extension 208 extending from a body 209 of the rotor shaft along the z-axis. In one example, the rotor shaft 204 can be formed as a hollow shaft having a cavity 211 inside the shaft, and specifically inside the body 209. However, in other examples, at least a portion of the rotor shaft can have a different profile. For example, at least a portion of the rotor shaft can be solid.

[0024] In the example shown, shaft extension 208 has a smaller diameter than shaft extension 218 and is therefore located closer to axis of rotation 206 than the shaft extension. Thus, a portion of shaft extension 208 may be circumferentially surrounded by shaft extension 218. Additionally, shaft extension 208 may extend axially outwardly farther from body 209 of shaft 204 than shaft extension 218. Shaping the rotor shaft with these extensions may position bearing 214 in a desired position within bearing cavity 220 and position end plate extension 210 radially inward from bearing 214 and provide a desired sealing function associated with bearing cavity 220 and cavity 235 in grounding system 221 discussed in greater detail herein. Additionally, shaft extension 208 and / or shaft extension 218 may have a cylindrical cross-section in an xy plane formed between the x-axis and the y-axis.

[0025] The extension 208 may be coupled to the extension 218 via a radially extending shaft portion 219. Furthermore, in the example shown, a cavity 235 is formed between the extension 208 and the extension 218. Furthermore, in the example shown, the end plate extension 210 cooperates with the cavity 235.

[0026] The grounding system 221 provides a path for the current to discharge and thus reduces the degradation of the bearing 214 caused by arc pitting. Thus, the life and reliability of the machine are increased. In addition, the grounding system is designed with features such as the grounding cam 224, which experiences less wear during operation compared to other grounding devices such as grounding brushes.

[0027] The grounding system 221 includes a grounding cover 222 coupled to the shaft extension 208 (e.g., the end 270 of the shaft extension 208). In some examples, the grounding cover 222 can be interlocked, riveted, and / or splined to the shaft extension 208. In this way, the grounding cover can be effectively connected to the rotor shaft during manufacturing. In other examples, the grounding cover 222 can be press-fit or threadedly attached to the shaft extension 208. Therefore, when the motor 200 rotates the rotor shaft, the grounding cover 222 can rotate in unison with the rotor shaft 204.

[0028] At least a portion of the ground cover 222 is electrically conductive. For example, the ground cover 222 may include metal conduit(s) 229 extending therethrough and providing a path for electrical current to discharge from the rotor shaft 204 and into the ground cover. Figure 2206. The metal conduit(s) 229 are schematically depicted in FIG. However, the metal conduit(s) 229 may have greater structural complexity. For example, the metal conduit(s) may extend radially outward from the central portion 231 of the ground cover 222 to an interface 233 between the cover and the shaft extension 208. In such an example, the multiple metal conduits may extend radially outward in this manner and may be arranged symmetrically relative to the rotation axis 206. In addition or alternatively, the material used to construct the body of the ground cover 222 may be conductive. In detail, the outer side surface 227 of the ground cover 222 may be constructed of a conductive material that extends continuously to the interface 233 between the ground cover and the shaft extension 208.

[0029] The inner surface 223 of the ground cover 222 can form a portion of the boundary of the internal cavity 211 of the rotor shaft 204. The outer surface 227 of the ground cover forms a portion of the boundary of the sealed cavity 330, which will be discussed in more detail herein. The outer surface 227 of the ground cover 222 is in electrical contact with the ground cam 224 included in the grounding system 221. In the example shown, the ground cam 224 contacts the ground cover 222 at a point along the rotation axis 206. Therefore, the ground cam 224 is aligned with the rotation axis 206. In this way, during operation of the motor, when the ground cover 222 rotates in unison with the rotor shaft 204, the movement of the ground cam 224 is reduced. The reduction in relative movement between the ground cam 224 and the ground cover 222 can reduce the amount of wear (e.g., degradation) of the ground cam and / or the ground cover.

[0030] The ground cover 222 and the ground cam 224 can each include a low friction material so that when the ground cover rotates against the ground cam, the friction between the ground cover and the ground cam is reduced. In addition, the ground cam 224 can be conductive so that the ground cover 222 and the ground cam create a path for current to discharge from the rotor shaft 204. The ground cam can be formed of copper, metal graphite, combinations thereof, etc. The portion of the ground cam 224 that contacts the ground cover 222 can be a tip of the ground cam, and the ground cam can become larger (e.g., have a larger diameter) as it moves away from the ground cover.

[0031] The grounding system 221 includes a grounding spring 226. The grounding spring 226 is conductive and is used to make the grounding cam 224 self-centering to reduce the relative movement of the cam (e.g., eliminate the relative movement of the cam). In detail, the grounding spring 226 includes a conductive path that can be formed via a wire, a material for constructing the grounding spring, a combination thereof, etc. The grounding spring 226 can be a coil spring, a wave spring, etc.

[0032] The grounding cam 224 can be maintained in coplanar contact with the grounding cover 222 by the grounding spring 226. The grounding spring 226 can be located between the grounding cam 224 and the end plate 212 of the housing 202. The grounding spring 226 is conductive so that, as described above, the grounding cover 222, the grounding cam 224, and the grounding spring 226 create a path for current to discharge from the rotor shaft 204. With the grounding spring 226 in cooperation with the end plate 212, the current can be discharged from the rotor shaft 204 to the housing 202 by passing through the grounding system 221. In this way, the amount of current discharged from the rotor shaft 204 through the bearing 214 can be reduced compared to a machine that does not include a grounding system, and thus, the degradation of the bearing can be reduced. In addition, the longitudinal axis of the grounding spring 226 is aligned with the rotational axis 206 of the rotor shaft 204. Therefore, the grounding spring 226 facilitates the grounding cam 224 to be centered on the rotational axis 206.

[0033] Figure 3 A detailed view of grounding system 221 is shown, which is positioned to discharge current from rotor shaft 204 to housing 202, which in some cases can reduce or avoid current that discharges from shaft extension 218 through bearing 214 and into housing 202. In detail, grounding system 221 provides a path for current to discharge from shaft extension 208, through the grounding system, and into end plate 212 of housing 202. Therefore, grounding system 221 can extend the life of bearing 214, thereby reducing the amount and / or frequency of motor maintenance and repair and extending motor life.

[0034] As previously discussed, the end plate 212 of the housing 202 may include an end plate extension 210. In detail, a portion of the end plate extension 210 may be located between the shaft extension 218 and the shaft extension 208. The end plate extension 210 may include a recess 302, which may extend around the outer circumferential surface of the end plate extension. Thus, the recess 302 may form an annular recess. The end plate extension 210 may additionally or alternatively include a recess 306, which may extend around the inner circumferential surface of the end plate extension. Thus, the recess 306 may form an inner annular recess. The recess 306 may be positioned closer to the end plate 212 relative to the z-axis, while the recess 302 may be positioned farther away from the end plate 212.

[0035] The shaft extension 218 may include a seal 304 that protrudes inward (e.g., toward the axis of rotation 206) and extends around the inner circumferential surface of the shaft extension. In addition, the shaft extension 208 may include a seal 308 that protrudes outward (e.g., away from the axis of rotation 206) and extends around the outer circumferential surface of the shaft extension. Seals 304 and 308 cooperate with recesses 302 and 306, respectively. The seal reduces the chance of fluid traveling between the seal cavity 330 and the bearing cavity 220 while allowing the rotor shaft to rotate and the housing to remain stationary relative to the rotor shaft. In this way, the chance of debris (e.g., shavings and / or powder) generated due to wear on the grounding cover 222 and / or the grounding cam 224 mixing with the fluid in the bearing cavity 220 is reduced. By keeping metal debris from the grounding cover 222 and / or the grounding cam 224 in the seal cavity 330, contamination of the lubricating fluid in the motor 200 can be reduced (e.g., prevented). In some examples, seal 304 can be an O-ring and seal 308 can be a slip ring. In such examples, the slip ring (e.g., seal 308) can be press-fit around the outer surface of shaft extension 208. In this way, seal cavity 330 can be reliably sealed. However, other suitable types of seals can be used in alternative examples. For example, the seal can be a slip ring or other suitable seal, such as a labyrinth seal, a lip seal, a rotating face seal, etc.

[0036] The grounding cover 222 of the grounding system 221 can be located at the end of the shaft extension 208. The peripheral edge 312 of the grounding cover 222 can be splined, interlocked, or riveted to the recess 310. In addition, the grounding cover 222 can include a lip 314. The lip 314 extends outward (e.g., away from the rotation axis 206) from the extension portion 313 of the grounding cover 222. Therefore, the lip 314 can be coplanar with the distal end of the shaft extension 208. In this way, in some cases, the lip 314 can reduce the amount of debris that contacts the seal 308 (e.g., slip ring, O-ring, etc.).

[0037] The grounding spring 226 includes a first end 320 and a second end 322. The first end 320 can be located in a recess 318 of the end plate 212 to axially constrain the spring and allow the spring to be compressed along the axis 206. The recess 318 can be formed in an extension 316, which can have a cylindrical shape and protrude inwardly from the center of the end plate 212 into the sealing cavity 330. The second end 322 of the grounding spring 226 can be located in a recess 324 of the grounding cam 224. The recess 324 is formed in a body 326 of the grounding cam 224, which can have a cylindrical shape and extend toward the end plate 212. Arranging the spring in this manner allows the spring to be compressed along the axis 206 and reduces undesirable movement of the spring out of alignment with the axis 206.

[0038] The grounding spring 226 can be compressed between the grounding cam 224 and the end plate 212 along the Z-axis. Thus, the grounding spring 226 can apply a force to the grounding cam 224, thereby pushing the grounding cam 224 into contact with the grounding cover 222. The force applied by the grounding spring 226 to the grounding cam 224 can also reduce the chance of the grounding cam moving out of alignment with the axis 206. In this way, degradation of the cams and covers (e.g., the grounding cam 224 and the grounding cover 222) caused by misalignment can be reduced.

[0039] The motor 200 may include a collection mechanism 328 located within the sealed cavity 330. The collection mechanism 328 collects debris generated by the rotation of the ground cover 222 against the ground cam 224. Therefore, the collection mechanism 328 can reduce the chance of debris degrading the seals 304 and 308. Therefore, the sealed cavity 330 can remain sealed and can keep the debris away from the oil or other suitable fluid present in the bearing cavity 220 and around the bearing 214. In some examples, the collection mechanism 328 can be a magnet that attracts metal powder, chips, etc. from the ground cam 224 and / or the ground cover 222. In addition, the collection mechanism 328 can be located in the lower portion of the sealed cavity 330, so that the metal powder and chips can travel to the mechanism by gravity. In this way, metal powder, chips, etc. can be collected, thereby reducing the chance of metal material migrating to unwanted areas of the machine. However, in alternative examples, the collection mechanism can be located in other suitable locations.

[0040] The grounding cam 224 can include a tip 334 that extends axially from the body 326 and includes a face 336 (e.g., a flat surface) that contacts the outer side surface 227 of the grounding cover 222. The tip 334 can taper in the medial direction along an axis parallel to the z-axis. Constructing the grounding cam 224 in this manner can enable the grounding cam to achieve increased durability.

[0041] Figure 4 A method 400 for assembling a grounding system to a rotor shaft of an electric machine is shown. In one example, the method 400 may be used to Figure 2 and Figure 3 The grounding system is assembled in the described electric machine. At least a portion of the method steps can be at least partially automatically implemented via a manufacturing device, which can include instructions for the method steps. The instructions can be stored in a memory, which can be executed by a processor of a controller. In addition, in some cases, at least a portion of the method steps can be manually performed by manufacturing personnel.

[0042] At 402, method 400 includes installing seals in an end plate and / or a rotor shaft. In detail, one seal may fit into a recess in the end plate while another seal is press-fit onto a rotor shaft extension.

[0043] At 404, method 400 includes attaching a grounding cover to an extension of a rotor shaft of the electric machine. For example, the grounding cover can be splined, interlocked, and / or riveted to a second extension of the rotor shaft. In addition, the grounding cam is conductive, creating a path for current to discharge from the rotor shaft and into the grounding cover.

[0044] At 406, method 400 includes fitting a first end of a grounding spring into a recess of a housing end plate. The housing end plate may include an annular extension protruding into the seal cavity having a recess located at a center of the extension. The recess may be cylindrical and may accommodate the first end of the grounding spring. By accommodating the first end of the grounding spring, the recess may reduce undesirable movement of the grounding spring and maintain alignment of the grounding spring with the rotational axis of the rotor shaft.

[0045] At 408, method 400 includes fitting the second end of the grounding spring into the recess of the grounding cam. The grounding cam may include a circular extension having a recess located at the center of the extension. The recess may be circular and may accommodate the second end of the grounding spring. The grounding spring may apply a force to the grounding cam that, once fully assembled, pushes the grounding cam into contact with the grounding cover.

[0046] At 410, method 400 includes coupling the end plate to the housing body and electrically contacting the cam with the grounding cover. For example, the end plate extension can cooperate with a recess formed between two rotor shaft extensions. The grounding cam can be centered on the grounding cover so that the contact point between the grounding cam and the grounding cover is positioned along the axis of rotation of the rotor. In this way, when the grounding cover rotates with the rotor, the undesirable movement of the grounding cam relative to the grounding cover can be reduced. Therefore, degradation of the grounding cover and / or the grounding cam is reduced. The grounding spring and the grounding cam are both conductive, and thus create a path with the grounding cover for current to discharge from the rotor shaft and enter the grounding spring. In detail, the grounding cover, the grounding cam and the grounding spring now provide a path for discharging current from the rotor to the housing. Therefore, the bearings of the motor can experience less discharge from the rotor and therefore have an increased life.

[0047] In this way, a system and method for grounding the rotor of an electric machine are presented. Contact between a stationary grounding cam and a rotating grounding cover is created at or very close to the axis of rotation of the grounding cover to reduce the translational movement of the grounding cam. A spring mechanism with a built-in conductive path is included to facilitate self-centering of the grounding cam, thereby reducing any relative movement. The material selected for the interface has ultra-low wear and good conductivity. In addition, a sealed chamber is formed by press-fitting the slip ring and O-ring on the rotor shaft, which separates the wet cavity from the sealed chamber containing the grounding cam and the grounding spring, and reduces metal powder, chips, etc. that may enter the wet cavity. A collection mechanism (e.g., a magnet) for potential wear powder is positioned in the chamber so that it does not affect the seal. Therefore, possible wear (due to the smaller potential movement of the grounding cam) is contained in the sealed cavity.

[0048] A technical effect of the method described herein is to effectively ground the rotor of an electric machine using a grounding cover, a grounding cam, and a grounding spring.

[0049] Figures 1 to 3 An exemplary configuration with relative positioning of various components is shown. In at least one example, if shown as being in direct contact or directly coupled to each other, such elements may be referred to as being in direct contact or directly coupled, respectively. Similarly, in at least one example, elements shown as being adjacent or adjacent to each other may be adjacent or adjacent to each other, respectively. As an example, components that are coplanarly in contact with each other may be referred to as coplanarly in contact. As another example, in at least one example, elements that are spaced apart and positioned from each other with no other components may be referred to as such. As another example, elements shown as being above / below each other, on opposite sides or on the left / right side of each other may be referred to as such relative to each other. In addition, as shown in the accompanying drawings, in at least one example, the topmost element or the vertex of an element may be referred to as the "top" of a component, and the bottommost element or the bottommost point of an element may be referred to as the "bottom" of a component. As used herein, top / bottom, upper / lower, above / below may be relative to the vertical axis of the accompanying drawings, and are used to describe the positioning of the elements of the accompanying drawings relative to each other. Thus, in one example, an element shown as being above other elements is located directly above other elements. As yet another example, shapes of elements depicted within the drawings may be referred to as having these shapes (e.g., such as being rounded, straight, planar, curved, rounded, chamfered, angled, etc.). Additionally, in at least one example, elements shown as intersecting each other may be referred to as intersecting elements or intersecting each other. Further, in one example, elements shown as being within another element or shown as being outside another element may be referred to as such.

[0050] In one example, a motor system is provided, the motor system comprising: a rotor shaft; a ground cover coupled to an end of the rotor shaft; a cam aligned with the rotation axis of the rotor shaft and electrically coupled to the ground cover; an end plate of a housing; and a spring extending between the cam and the inner surface of the housing; wherein the ground cover, the cam and the spring are conductive. In a first example of the system, the cam may include a recess that fits with the end of the spring. In a second example of the system (optionally including the first example), the ground cover may be splined to the rotor shaft. In a third example of the system (optionally including one or both of the first example and the second example), the ground cover may be interlocked to the rotor shaft. In a fourth example of the system (optionally including one or more of each of the first to third examples), the ground cover may be riveted to the rotor shaft. In a fifth example of the system (optionally including one or more of each of the first to fourth examples), the ground cover may include a metal conduit extending therethrough. In a sixth example of the system (optionally including one or more of each of the first to fifth examples), the housing may include an inward protrusion, the inward protrusion includes a recess, and the end of the spring may cooperate with the recess. In a seventh example of the system (optionally including one or more of each of the first to sixth examples), the ground cover and the housing may form a sealed cavity. In an eighth example of the system (optionally including one or more of each of the first to seventh examples), the system may further include a magnet located in the sealed cavity. In a ninth example of the system (optionally including one or more of each of the first to eighth examples), the motor system may be a traction motor.

[0051] In another example, a method for operating a motor system is provided, comprising: rotating a rotor shaft while the rotor shaft is electrically grounded, wherein the motor system comprises: the rotor shaft; a ground cover coupled to an end of the rotor shaft; a cam aligned with an axis of rotation of the rotor shaft and electrically coupled to the ground cover; and a spring extending between the cam and an inner surface of the housing, wherein the ground cover, the cam, and the spring are electrically conductive. In a first example of the method, the ground cover and the housing form a sealed cavity, and the motor system may further include a seal located between the rotor shaft and the housing.

[0052] In yet another example, an electric motor is provided, the electric motor comprising: a rotor shaft; a ground cover coupled to an end of the rotor shaft; a cam electrically coupled to the ground cover; an end plate of a housing; and a spring extending between the cam and an inner surface of the end plate and aligned with the rotational axis of the rotor shaft, wherein the spring and the cam are aligned with the rotational axis of the rotor shaft, and wherein the ground cover, the cam, and the spring are electrically conductive. In a first example of the electric motor, the end plate may include a radially extending protrusion having an inner surface with a first groove and an outer surface with a second groove, the first groove having a first seal located therein, and the second groove having a second seal located therein; and the first seal and the second seal may contact an extension of the end of the rotor shaft. In a second example of the electric motor (optionally including the first example), the ground cover may be splined, interlocked, and / or riveted to the rotor shaft. In a third example of the electric motor (optionally including one or both of the first and second examples), the ground cover may be located outside the rotor shaft bearing. In a fourth example of the electric motor (optionally including one or more of each of the first to third examples), the ground cover and the end plate may form a sealed cavity. In a fifth example of the electric motor (optionally including one or more of each of the first to fourth examples), the electric motor may further include a collection device located in the sealed cavity. In a sixth example of the electric motor (optionally including one or more of each of the first to fifth examples), the collection device may include a magnet. In a seventh example of the electric motor (optionally including one or more of each of the first to sixth examples), the spring may include a first end that cooperates with a first recess in the cam and a second end that cooperates with a recess in an inwardly protruding section of the end plate.

[0053] It should be noted that the exemplary assembly procedures included herein can be used with various system configurations. The assembly methods and routines disclosed herein can be stored in non-transitory memory as executable instructions, and can be executed by a manufacturing system including a controller in combination with various sensors, actuators and other hardware. The specific program described herein can represent one or more of any number of processing strategies (such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc.). To this end, the various actions, operations and / or functions shown can be executed in the sequence described, executed in parallel, or omitted in some cases. Similarly, the processing order is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of explanation and description. One or more of the actions, operations and / or functions shown can be repeatedly performed according to the specific strategy used. In addition, the described actions, operations and / or functions can graphically represent the code in the non-transitory memory of the computer-readable storage medium that will be programmed into the manufacturing system, wherein the described actions are implemented by executing instructions in a system including various hardware components in conjunction with an electronic controller.

[0054] It should be understood that the configurations and procedures disclosed herein are exemplary in nature, and these specific embodiments should not be considered to have a limiting meaning, as many variations are possible. In addition, unless explicitly stated to the contrary, the terms "first," "second," "third," etc. are not intended to represent any order, position, quantity, or importance, but are merely used as markers to distinguish one element from another. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and / or properties disclosed herein.

[0055] The appended claims particularly point out certain combinations and subcombinations deemed novel and non-obvious. These claims may refer to "an" element or "a first" element or the equivalent thereof. Such claims will be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amendment of the present claims or by presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, are also deemed to be included in the subject matter of the present disclosure.

[0056] According to the present invention, a motor system is provided, the motor system having: a rotor shaft; a ground cover, the ground cover being coupled to the end of the rotor shaft; a cam, the cam being aligned with the rotation axis of the rotor shaft and being electrically coupled to the ground cover; an end plate of a housing; and a spring, the spring extending between the cam and the inner surface of the housing; wherein the ground cover, the cam and the spring are electrically conductive.

[0057] According to one embodiment, the cam comprises a recess cooperating with an end of the spring.

[0058] According to one embodiment, the ground cover is splined to the rotor shaft.

[0059] According to one embodiment, the ground cover is interlocked to the rotor shaft.

[0060] According to one embodiment, the ground cover is riveted to the rotor shaft.

[0061] According to one embodiment, the ground cover includes a metal conduit extending therethrough.

[0062] According to one embodiment: the housing comprises an inwardly protruding portion, the inwardly protruding portion comprises a recess; and the end of the spring cooperates with the recess.

[0063] According to one embodiment, the ground cover and the housing form a sealed cavity.

[0064] According to one embodiment, the invention also features a magnet located in the sealed cavity.

[0065] According to one embodiment, the electric machine system is a traction motor.

[0066] According to the present invention, a method for operating a motor system includes: rotating a rotor shaft while the rotor shaft is electrically grounded, wherein the motor system includes: the rotor shaft; a ground cover, the ground cover is connected to the end of the rotor shaft; a cam, the cam is aligned with the rotation axis of the rotor shaft and is electrically coupled to the ground cover; and a spring, the spring extending between the cam and the inner surface of the housing, wherein the ground cover, the cam and the spring are conductive.

[0067] In one aspect of the present invention, the ground cover and the housing form a sealed cavity, and the motor system further comprises a seal located between the rotor shaft and the housing.

[0068] According to the present invention, an electric motor is provided, the electric motor having: a rotor shaft; a ground cover connected to the end of the rotor shaft; a cam electrically coupled to the ground cover; an end plate of a housing; and a spring extending between the cam and an inner surface of the end plate and aligned with the rotational axis of the rotor shaft, wherein the spring and the cam are aligned with the rotational axis of the rotor shaft, and wherein the ground cover, the cam and the spring are electrically conductive.

[0069] According to one embodiment, the end plate includes a radially extending protrusion having an inner surface with a first groove and an outer surface with a second groove, the first groove having a first seal located therein and the second groove having a second seal located therein; and the first seal and the second seal contact an extension of the end of the rotor shaft.

[0070] According to one embodiment, the ground cover is splined, interlocked and / or riveted to the rotor shaft.

[0071] According to one embodiment, the ground cover is located outside the rotor shaft bearing.

[0072] According to one embodiment, the ground cover and the end plate form a sealed cavity.

[0073] According to one embodiment, the invention is also characterized by a collection device located in the sealed cavity.

[0074] According to one embodiment, said collecting means comprise a magnet.

[0075] According to one embodiment, the spring comprises: a first end cooperating with a first recess in the cam; and a second end cooperating with a recess in the inwardly protruding section of the end plate.

Claims

1. A motor system, comprising: Rotor shaft; a ground cover coupled to an end of the rotor shaft; a cam aligned with the rotational axis of the rotor shaft and electrically coupled to the grounded cover; an end plate of the shell; as well as a spring extending between the cam and an inner surface of the housing; Wherein, the ground cover, the cam and the spring are conductive.

2. The motor system of claim 1, wherein: The cam includes a recess that cooperates with an end of the spring.

3. The motor system of claim 1, wherein: The ground cover is splined to the rotor shaft.

4. The motor system of claim 1, wherein: The ground cover is interlocked to the rotor shaft.

5. The motor system of claim 1, wherein: The ground cover is riveted to the rotor shaft.

6. The motor system of claim 1, wherein: The ground cover includes a metal conduit extending therethrough.

7. The electric machine system of claim 1, wherein: The housing includes an inwardly projecting portion, the inwardly projecting portion including a recess; and The end of the spring is engaged with the recess.

8. The motor system of claim 1, wherein: The grounding cover and the shell form a sealed cavity.

9. The electric machine system of claim 8, further comprising a magnet located in the sealed cavity.

10. The motor system of claim 1, wherein: The electric machine system is a traction motor.

11. The electric machine system of claim 1 , wherein: The end plate includes a radially extending projection having an inner surface with a first groove having a first seal positioned therein and an outer surface with a second groove having a second seal positioned therein; and The first seal and the second seal contact an extension of an end portion of the rotor shaft.

12. The motor system of claim 1, wherein: The ground cover is splined, interlocked and / or riveted to the rotor shaft.

13. The electric machine system of claim 1, wherein: The grounding cover is located outside the rotor shaft bearing; and / or The ground cover and the end plate form a sealed cavity.

14. A method for operating a motor system, comprising: rotating the rotor shaft while the rotor shaft is electrically grounded; Wherein, the motor system comprises: the rotor shaft; a ground cover coupled to an end of the rotor shaft; a cam aligned with the rotational axis of the rotor shaft and electrically coupled to the grounded cover; and a spring extending between the cam and an inner surface of the housing; Wherein, the ground cover, the cam and the spring are conductive.

15. The method of claim 14, wherein: The ground cover and the housing form a sealed cavity, and the motor system further includes a seal located between the rotor shaft and the housing.

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