E-machine sealing ring

Abstract

An e-machine including a stator member and a rotor member. The e-machine includes a housing at least partially surrounding the stator member and the rotor member. One or more bearings rotatably support the rotor member within the housing. The rotor member includes an electrically conductive sealing ring disposed thereon. The sealing ring contacts a surface of the rotor member and a surface of the housing to form a fluid seal therebetween.

Description

Atty Docket: GAR G001550 IAE-MACHINE SEALING RINGTECHNICAL FIELD

[0001] The present disclosure relates, generally, to grounding devices for controlling shaft currents that are generated in e-machines such as e-motors.BACKGROUND

[0002] Shaft induced electrical current is experienced in e-machines such as e-motors.During the operation of the e-machine, capacitive electrical discharge machining (EDM) currents and other high-frequency circulating currents cause voltage to be accumulated in the rotor of the e-machine. Without a dedicated discharging technique, this accumulated voltage typically discharges through the bearings. This is undesirable, since discharge of this voltage through the bearings causes degradation of the bearings via electrical erosion phenomena.

[0003] In order to prevent discharge of the accumulated voltage through the bearings, a grounding brush ring is typically used. A grounding brush ring typically comprises conductive filament bristles that electrically connect a surface of the rotor of the e-machine to a suitable grounding location to thereby provide an alternative electrical discharge path from the rotor, thereby protecting the bearings from electrical erosion phenomena.

[0004] However, grounding brush rings are a relatively expensive solution to this degradation problem. It would be desirable to provide a less expensive technique for providing an alternative electrical discharge path from a rotor of an e-machine to ground, as well as other advantages.BRIEF SUMMARY

[0005] This summary is provided to describe select concepts in a simplified form that are further described in the Detailed Description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0006] According to a first aspect of the invention, there is provided an e-machine comprising a stator member; a rotor member; and a housing at least partially surrounding the stator member and the rotor member. One or more bearings rotatably support the rotor member within the housing. The rotor member includes an electrically conductive sealingAtty Docket: GAR G001550 IAring disposed thereon, the electrically conductive sealing ring contacting a surface of the rotor member and a surface of the housing to form a fluid seal therebetween.

[0007] According to embodiments, the rotor member comprises a groove, and wherein the sealing ring is partially disposed within the groove such that at least one sidewall of the sealing ring is in contact with a sidewall of the groove.

[0008] According to embodiments, the sealing ring is partially disposed within the groove by means of a clearance fit.

[0009] According to embodiments, a radially outer surface of the sealing ring contacts a radially inner surface of a bore formed within the housing.

[0010] According to embodiments, in a relaxed state, an outer diameter dimension of the sealing ring is greater than an inner diameter dimension of the bore such that, when the sealing ring is installed in the bore, the sealing ring is forced into a compressed state.

[0011] According to embodiments, the sealing ring is formed from steel, for example EN 1.3343, Stainless steel 420 or EN 1.4980.

[0012] According to embodiments, an electrical path from the rotor member to the housing across the sealing ring has a lower electrical resistance as compared to an electrical path from the rotor member to the housing across the bearings.

[0013] According to embodiments, the rotor member comprises a plurality of sealing rings.

[0014] According to embodiments, the e-machine is an electric generator.

[0015] According to embodiments, the e-machine is an electric motor.

[0016] According to embodiments, the e-machine does not include a grounding brush ring containing brush-type filaments configured to contact the rotor member.

[0017] According to embodiments, the sealing ring comprises a low-friction coating.

[0018] According to a second aspect of the invention, there is provided an e-machine system comprising the e-machine of any of the above aspects or embodiments, wherein the e-machine system further comprises a fluid coolant system configured to provide pressurized fluid coolant to the stator member and the rotor member, and wherein the sealing ring is configured to seal against the pressurized fluid coolant to prevent passage thereof.

[0019] According to a third aspect of the invention, there is provided a vehicle comprising the e-machine system of the second aspect, wherein the e-machine in the e-machine system is an electric motor configured to provide propulsion to at least one wheel of the vehicle.

[0020] According to a fourth aspect of the invention, there is provided a method of assembling an e-machine. The method comprises providing a rotor member including a groove; attaching a sealing ring to the groove, the sealing ring being electrically conductive;Atty Docket: GAR G001550 IAand installing the rotor member within a stator member, the stator member having a housing, such that the sealing ring contacts both a surface of the groove and a surface of the housing to form a fluid seal therebetween and such that a grounding path is formed from the rotor member to the housing via the sealing ring.

[0021] According to embodiments, the step of attaching the sealing ring to the groove comprises forming a clearance fit between the sealing ring and the groove.

[0022] According to embodiments, the step of installing the rotor member within the stator member comprises forming an interference fit between the sealing ring and a bore of the housing.

[0023] Other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the preceding background.BRIEF DESCRIPTION OF DRAWINGS

[0024] The present disclosure will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein:

[0025] FIG. 1 is a schematic illustration of circulating currents within an e-machine;

[0026] FIG. 2 shows a grounding brush ring according to the prior art;

[0027] FIG. 3 shows a schematic of an e-machine in accordance with embodiments;

[0028] FIG. 4 shows a representation of an e-machine including a sealing ring in accordance with embodiments;

[0029] FIG. 5 shows a representation of the sealing ring of FIG. 3 installed within an e-machine;

[0030] FIGs. 6A and 6B show a schematic illustrating an assembly technique in accordance with embodiments;

[0031] FIGs. 7A, 7B and 7C show a technique of installing a sealing ring according to embodiments; and

[0032] FIG. 8 shows a flowchart detailing a method of assembly of an e-machine in accordance with embodiments.DETAILED DESCRIPTION

[0033] The following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or the application and uses of the present disclosure. As usedAtty Docket: GAR G001550 IAherein, the word “exemplary” means “serving as an example, instance, or illustration.” Thus, any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. All of the embodiments described herein are exemplary embodiments provided to enable persons skilled in the art to make or use the present disclosure and not to limit the scope of the present disclosure, which is defined by the claims. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary, or the following detailed description.

[0034] Broadly, example embodiments disclosed herein include an e-machine system, such as an electric motor (e-motor) system. It will be appreciated that whilst the below explanation is provided with respect to e-motors, the teachings provided herein may also be applied to electric generators.

[0035] FIG. 1 shows a known e-motor 1 comprising a stator member 10 and a rotor member 20. As the rotor member 20 rotates, capacitive EDM and high-frequency circulating currents interact between the rotor member 20 and the stator member 10, which causes voltage to accumulate on the rotor member 20. Without a grounding technique, this accumulated voltage discharges from the rotor member 20 via bearings 30 of the e-motor 1 to a ground location 40, for example a housing associated with the stator member 10, which voltage discharge causes an undesirable electrical erosion of the bearings 30.

[0036] In order to mitigate against this undesirable erosion of the bearings, grounding brush rings have conventionally been used. FIG. 2 shows a schematic of a grounding brush ring 2. The grounding brush ring 2 is configured to indirectly or directly attach to a location on the stator 10 and to surround the rotor 20. The grounding brush ring 2 comprises electrically conductive brush filaments 21 (such as carbon fiber brush filaments, copper wire filaments or another type of electrically conductive brush filament) which conductive brush filaments contact a surface of the rotor member 20 as it rotates. The conductive brush filaments 21 provide an electrically conductive path from the rotor member 20 to a grounding location, for example to the stator member 10 or a housing associated therewith, which electrically conductive path bypasses the bearings 30 of the e-motor.

[0037] The present inventors have recognized that several disadvantages are associated with grounding brush rings 2. Grounding brush rings are relatively expensive. Additionally, grounding brush rings may operate sub-optimally at higher rotational speeds of the rotor member 20, such as rotational speeds in excess of around 25,000 RPM.Atty Docket: GAR G001550 IA

[0038] FIG. 3 is a schematic view of an e-machine system 100 according to example embodiments of the present disclosure.

[0039] The e-machine system 100 may have a variety of configurations. In some embodiments, the e-machine system 100 may be configured as a traction drive system 102 that is included, for example, on a vehicle 106. Thus, the traction drive system 102 may be configured for driving one or more wheels 104 of the vehicle 106. More specifically, the wheels 104 may be included at opposite ends of an axle 111, and a chassis 107 may be supported on the wheels 104 by a suspension system (not shown). The vehicle 106 may be an electric car, truck, van, motorcycle, boat, or other vehicle. However, it will be appreciated that the e-machine system 100 may be configured otherwise without departing from the scope of the present disclosure, such as in the form of an electric generator that is not included on a vehicle.

[0040] Generally, the e-machine system 100 may include a system housing 125. The system housing 125 may include or be an e-machine housing 124 with a cavity 129 defined therein. The e-machine system 100 may also include an e-machine 110 that is received within the cavity 129 and housed within the e-machine housing 124.

[0041] The e-machine 110 may be an electric motor 112. For example, in some embodiments, the electric motor 112 may be an AC three-phase electric motor. However, it will be appreciated that the e-machine 110 may be configured otherwise. The e-machine 110 may alternatively be configured as an electric generator. Furthermore, the e-machine 110 may be operable in some modes as a motor and in additional modes as a generator. The e-machine 110 includes a rotor member 118 and a stator member 119 that are housed within the cavity 129 of the e-machine housing 124.

[0042] The rotor member 118 may be supported on a shaft 116, and the shaft 116 is supported for rotation about a longitudinal axis 109 within the e-machine housing 124. The stator member 119 of the e-machine 110 may be fixed within the e-machine housing 124 and at least partly surrounds the rotor member 118 and the shaft 116. In embodiments in which the e-machine 110 is an electric motor 112, the shaft 116 may be referred to as an output shaft 116 of the electric motor 112. In some embodiments, such as when the e-machine system 100 is mounted on a vehicle 106, a gear connection member 128 (e.g., a gear, a spline on the shaft 116, or other part with gear teeth features) may be operably supported on the shaft 116.

[0043] In various embodiments, the e-machine system 100 includes a transmission 130. The transmission 130 may include a geartrain 132 that is housed within a gearbox housing 136 ofAtty Docket: GAR G001550 IAthe housing 125. The gearbox housing 136 may be attached (e.g., fixed) to a wall 127 of the e-machine housing 124.

[0044] The geartrain 132 may operatively connect the e-machine 110 and the axle 111 and may transmit power therebetween. The e-machine 110 may be coupled to the wheels 104 via the transmission 130. The geartrain 132 may be attached to the gear connection member 128 and to the axle 111. The gearbox housing 136 and the e-machine housing 124 may be moveably supported on the axle 111 by one or more axle bearings 114 (e.g., a bearing sleeve, suspension tube, etc.) such that the axle 111 may rotate relative thereto.

[0045] The stator member 119 includes a plurality of windings (i.e., winding members, wiring members, etc.). The windings are electrically conductive. The windings are arranged in a plurality of coils that wrap back-and-forth between axial ends of the stator member 119, for example in slots formed in the stator member 119.

[0046] During operation, the electric motor 112 may rotatably drive the shaft 116 and the gear connection member 128 supported thereon. This rotational power may transfer to the geartrain 132, which may transmit the power to the axle 111 to rotate the wheels 104 and propel the vehicle 106. These operations may be controlled by a control system 133. The control system 133 may control speed of the motor 112 and / or other functions of the motor 112.

[0047] Furthermore, the e-machine system 100 may include a fluid coolant system 140. The fluid coolant system 140 may be configured for circulating a fluid, such as a fluid coolant. The fluid coolant may be oil, for example. In embodiments, the fluid coolant system 140 is configured to supply pressurized fluid coolant, and may comprise a pump or other such means for delivering pressurized fluid coolant. This fluid coolant may be provided to the slots so as to flow amongst the windings disposed in the slots of the stator member 119. Thus, fluid coolant may be provided directly to flood the windings and the stator member 119 for effective cooling of the stator member 119 via direct slot cooling.

[0048] The fluid coolant system 140 is coupled to the stator member 119. Accordingly, the fluid coolant system 140 is configured to provide cooling to the stator member 119. This, in turn, provides cooling to the rotor member 118, to bearings supporting the rotor member, and / or to other adjacent areas of the e-machine 110. In embodiments, the fluid coolant system 140 provides fluid coolant to the slots of the stator member 119 within which windings (not shown) of the stator are located.

[0049] The slots of the stator member 119 may be “open” to allow for fluid coolant to flow to and around the rotor member 118 in order to cool the rotor member 118. In such anAtty Docket: GAR G001550 IAarrangement, it is desirable to provide a seal around the rotor member 118 to prevent the fluid coolant from flowing out of the stator member 119.

[0050] The present inventors recognized that it is possible to both solve the problem of providing an adequate seal to retain fluid coolant around the rotor member 118 and inside of the stator member 119 and also to solve the problem of providing an electrical discharge path circumventing the bearings supporting the rotor member 118 that does not require an expensive grounding brush ring and whilst also allowing for adequate grounding performance at high rotational speeds of the rotor member 118.

[0051] Turning to FIG. 4, an arrangement of an e-machine system 100 including a sealing ring 150 is shown. The sealing ring 150 is preferably seated inside a groove 155 formed in the rotor member 118 with a portion of the sealing ring 150 extending out of the groove 155, such that the sealing ring is partially disposed within the groove 155. The sealing ring 150 is configured to contact surfaces of both the rotor member 118 and the e-machine housing 124 so as to both provide an adequate seal against fluid coolant egressing out of the stator member 119 and also to provide an electrical discharge path that circumvents the bearings 30 supporting the rotor member 118 within the stator member 119. In other words, the sealing ring 150 is configured to provide a seal between the static e-machine housing 124 and the dynamic rotor member 118 so as to prevent or minimize the passage of fluid coolant out of the stator member 119, and the sealing ring 150 is formed from an electrically conductive material to allow for voltage accumulated on the rotor member 118 to be discharged via a route that avoids the bearings 30 supporting the rotor member 118.

[0052] It will also be appreciated that, whilst the above explanation is given with respect to the sealing ring 150 being provided between the e-machine housing 124 and the rotor member 118, the sealing ring 150 may alternatively be provided to create a seal between the rotor member 11 and another housing of the e-machine system, such as a bearing housing or another suitable housing.

[0053] As noted above, the seal created by the sealing ring 150 is formed by contacting part of side walls of the sealing ring 150 against surfaces of opposing side walls of a groove 155 formed in the rotor member 118 and contacting an outer diameter surface of the sealing ring 150 against an inner diameter surface of a bore 300 in which the rotor member 118 is located, for example a bore of the e-machine housing 124 or a bore of a bearing housing. FIG. 5 shows a three-dimensional representation of a sealing ring 150 disposed within a groove 155 formed in the rotor member 118. As can be seen in this figure, sidewalls 151 of the sealing ring 150 contact side walls 156 of the groove 155.Atty Docket: GAR G001550 IA

[0054] The sealing ring 150 may be assembled onto the rotor member 118 by means of an clearance fit. In other words, a width of the sealing ring 150 (i.e., the dimension of the sealing ring parallel to the longitudinal axis) is slightly smaller than a width of the groove 155, such that a small axial gap exists between at least one sidewall of the sealing ring 150 and a sidewall of the groove 155. In embodiments, the width of the sealing ring 150 is smaller than the width of the groove 155 by less than 0.1mm, for example between 0.03mm and 0.07mm. A small axial clearance between the sidewalls of the sealing ring 150 and the sidewalls of the groove 155 allows for smooth rotation of the sealing ring 150 even at high rotational speeds.

[0055] It is to be noted that, even with a small axial clearance between the sidewalls of the sealing ring 150 and the sidewalls of the groove 155, the interface formed between the sealing ring 150 and the groove 155 is still effective at sealing against the egress of fluid coolant, because in order to egress through this interface fluid coolant must traverse along one sidewall of the groove 155 in a first direction perpendicular to the longitudinal axis, then in a second direction parallel to the longitudinal axis, and then in a third direction opposite to the first direction. Such a tortuous path is effective at sealing against egress of fluid coolant, especially at high rotational speeds where centripetal forces act upon the fluid coolant.

[0056] Furthermore, during typical operation, axial movement of the rotor causes at least one sidewall of the sealing ring 150 to be forced into engagement with at least one sidewall of the groove 155, thereby eliminating the axial clearance between these sidewalls.

[0057] After the sealing ring 150 has been assembled onto the rotor member 118 by means of a clearance fit, the rotor member 118 may be introduced into the bore 300 in such a manner as to form an interference fit between the sealing ring 150 and the bore 300. As will be explained in more detail below, this interference fit is typically achieved by resiliently compressing the sealing ring 150 in a radial direction when the rotor member 118 is introduced into the bore 300, such that the bore exerts a compression force on the sealing ring 150 when the sealing ring 150 is positioned inside the bore 300, thereby forming a seal between a radially outer surface of the sealing ring 150 and a radially interior surface of the bore 300. In other words, a diameter of a “relaxed” state of the sealing ring 150 is larger than the diameter of the bore into which the sealing ring 150 will subsequently be placed, such that a spring force of the stressed sealing ring will force an outer diameter surface of the sealing ring 150 against an inner diameter surface of the bore 300 of the housing 124 in which the sealing ring 150 is located.

[0058] The seal formed by the sealing ring is therefore formed by the interface between the radially outer surface of the sealing ring 150 and the radially inner surface of the bore 300 ofAtty Docket: GAR G001550 IAthe housing 124 within which the sealing ring 150 is located and also by the interface between the sidewalls 151 of the sealing ring 150 and the sidewalls 156 of the groove 155 within which the sealing ring 150 is seated.

[0059] It is noted that whilst the above figures show the presence of only a single sealing ring 150 and a single groove 155, a plurality of sealing rings 150 and / or grooves 155 may be included to improve the seal against fluid coolant and also to introduce additional electrical discharge paths between the rotor member 118 and the e-machine housing 124 or other housing, such as a bearing housing. For example, a plurality of sealing rings 150 may be provided in respective grooves 155, or a plurality of sealing rings 150 may be provided in a single, wide groove 155 such that opposing sidewalls of respective sealing rings 150 of the plurality of sealing rings 150 contact each other.

[0060] Turning to FIG. 6A and FIG. 6B, a schematic showing how a rotor member 118 including a sealing ring 150 may be assembled into a stator member 119 of an e-machine 100. Firstly, as shown in FIG. 6A, a sealing ring 150 may be forcibly expanded over the rotor member 118 and seated within a groove 155 formed in the rotor member 118. As noted above, a width w; of the sealing ring 150 may be relatively smaller than a width HA of the groove 155 such that the sealing ring 150 is clearance fit into the groove 155. Secondly, as shown in FIG. 6B, the rotor member 118 is then forced into a bore 300 of the housing 124. The outer diameter of the sealing ring 150 is configured to be relatively larger than the inner diameter of the bore 300 of the housing 124, such that the sealing ring 150 is compressed by the inner diameter surface of the bore 300 to form an interference fit. The seal formed by the interface between the sealing ring 150 and the groove 155 and between the interface of the radially outer surface of the sealing ring 150 and the radially inner surface of the bore 300 of the housing 124 is therefore effective in preventing egress of fluid coolant, even if the fluid coolant were to have a high pressure. Additionally, the sealing ring 150 is formed from an electrically conductive material, such that it may form an electrical discharge path that avoids bearings of the e-machine. In embodiments, the electrical path from the rotor member 118 to the housing 124 via the sealing ring 150 has a lower electrical resistance as compared to the electrical path from the rotor member 118 to the housing 124 via bearings supporting the rotor member 118.

[0061] It will also be appreciated that the sealing ring 150 is free of brush-type fdaments. As such, the sealing ring may provide effective grounding under higher rotational speeds as compared to a grounding brush ring containing brush-type conductive filaments. Although not necessary, in order to allow for the sealing ring 150 to provide effective grounding atAtty Docket: GAR G001550 IAhigher rotational speeds, the sealing ring 150 may be provided with a low-friction coating that is electrically conductive, for example a nickel-based coating or a Teflon-based coating.

[0062] Turning to FIGs. 7A to 7C, a figure is shown which illustrates how the interference fit between the sealing ring 150 and the bore 300 is formed according to an embodiment.

[0063] In FIG. 7A, a sealing ring 150 is provided. In an embodiment, the sealing ring 150 is has a gap 700 formed therein. In a relaxed state of the sealing ring 150, a diameter di of the diameter is greater than a diameter d: of the bore 300 within which the sealing ring 150 will subsequently be disposed. The sealing ring 150 may be assembled, in its relaxed state, onto a rotor member (not shown in this figure). It will be appreciated that whilst the sealing ring 150 is shown with a gap 700, the sealing ring 150 may also be provided without a gap 700.However, the presence of a gap 700 in the sealing ring 150 allows for increased manufacturing tolerances.

[0064] In FIG. 7B, the sealing ring 150 is radially compressed as it is entered into a bore. As can be seen in FIG. 7B, this radially compression may close the gap 700 of the sealing ring 150, if such a gap 700 is present. In this radially compressed state, the sealing ring 150 is entered into the bore.

[0065] In FIG. 7C, once the sealing ring 150 is placed inside the bore 300, the radial compression force is released and the sealing ring 150 radially expands such that a radially outer surface of the sealing ring 150 contacts a radially inner surface of the bore 300 in an interference-type fit.

[0066] A flowchart illustrating a method 800 of assembly of an e-machine, such as an electric motor, is shown in FIG. 8. At step 801, the method comprises providing a rotor member including a groove. The method then progresses to step 802. At step 802, a sealing ring is attached to the groove. Preferably, the sealing ring is attached to the groove by means of a clearance fit. The method then progresses to step 803. At step 803, the rotor member with the attached sealing ring is fit into a stator member. The stator member has a housing, for example an e-machine housing or a bearing housing. When the rotor member is fit into the stator member, the sealing ring forms a seal with surfaces of a bore of the housing with an interference-type fit. Due to the sealing ring being electrically conductive, a grounding path is formed, via the sealing ring, between the rotor member and the housing.

[0067] In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Numerical ordinals such as “first,” “second,” “third,” etc. simply denote different singles of aAtty Docket: GAR G001550 IAplurality and do not imply any order or sequence unless specifically defined by the claim language. The sequence of the text in any of the claims does not imply that process steps must be performed in a temporal or logical order according to such sequence unless it is specifically defined by the language of the claim. The process steps may be interchanged in any order without departing from the scope of the present disclosure as long as such an interchange does not contradict the claim language and is not logically nonsensical.

[0068] Furthermore, depending on the context, words such as “connect” or “coupled to” used in describing a relationship between different elements do not imply that a direct physical connection must be made between these elements. For example, two elements may be connected to each other physically, electronically, logically, or in any other manner, through one or more additional elements.

[0069] As used herein, the term “axial” refers to a direction that is generally parallel to or coincident with an axis of rotation, axis of symmetry, or centerline of a component or components. For example, in a cylinder or disc with a centerline and generally circular ends or opposing faces, the “axial” direction may refer to the direction that generally extends in parallel to the centerline between the opposite ends or faces. In certain instances, the term “axial” may be utilized with respect to components that are not cylindrical (or otherwise radially symmetric). For example, the “axial” direction for a rectangular housing containing a rotating shaft may be viewed as a direction that is generally parallel to or coincident with the rotational axis of the shaft. Furthermore, the term “radially” as used herein may refer to a direction or a relationship of components with respect to a line extending outward from a shared centerline, axis, or similar reference, for example in a plane of a cylinder or disc that is perpendicular to the centerline or axis. In certain instances, components may be viewed as “radially” aligned even though one or both of the components may not be cylindrical (or otherwise radially symmetric). Furthermore, the terms “axial” and “radial” (and any derivatives) may encompass directional relationships that are other than precisely aligned with (e.g., oblique to) the true axial and radial dimensions, provided the relationship is predominantly in the respective nominal axial or radial direction. As used herein, the term “substantially” denotes within 5% to account for manufacturing tolerances. Also, as used herein, the term “about” denotes within 5% to account for manufacturing tolerances.

[0070] While at least one exemplary embodiment has been presented in the foregoing detailed description of the present disclosure, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, orAtty Docket: GAR G001550 IAconfiguration of the present disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the present disclosure. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the present disclosure as set forth in the appended claims.

Claims

Atty Docket: GAR G001550 IACLAIMSWhat is claimed is:

1. An e-machine (110) comprising:a stator member (119);a rotor member (118);a housing (124) at least partially surrounding the stator member (119) and the rotor member (118);one or more bearings (30) rotatably supporting the rotor member (118) within the housing (124);characterized in that the rotor member (119) includes an electrically conductive sealing ring (150) disposed thereon, the electrically conductive sealing ring contacting a surface of the rotor member (118) and a surface of the housing (124) to form a fluid seal therebetween.

2. The e-machine of claim 1, wherein the rotor member (118) comprises a groove (1 5), and wherein the sealing ring (150) is partially disposed within the groove (155) such that at least one sidewall (151) of the sealing ring is in contact with a sidewall (156) of the groove (155).

3. The e-machine of claim 2, wherein the sealing ring (150) is partially disposed within the groove (155) by means of a clearance fit.

4. The e-machine of any preceding claim, wherein a radially outer surface of the sealing ring (150) contacts a radially inner surface of a bore (300) formed within the housing (124).

5. The e-machine of claim 4, wherein, in a relaxed state, an outer diameter dimension of the sealing ring (150) is greater than an inner diameter dimension of the bore (300) such that, when the sealing ring (150) is installed in the bore (300), the sealing ring (150) is forced into a compressed state.

6. The e-machine of any preceding claim, wherein the sealing ring is formed from sealing ring is formed from steel, optionally EN 1.3343, Stainless steel 420 or EN 1.4980.

7. The e-machine of any preceding claim, wherein an electrical path from the rotor member (118) to the housing (124) across the sealing ring (115) has a lower electricalAtty Docket: GAR G001550 IAresistance as compared to an electrical path from the rotor member (118) to the housing (124) across the bearings (30).

8. The e-machine of any preceding claim, wherein the rotor member (118) comprises a plurality of sealing rings (150)9. The e-machine of any preceding claim, wherein the e-machine is an electric generator.

10. The e-machine of any preceding claim, wherein the e-machine is an electric motor.

11. An e-machine system (100) comprising the e-machine (110) of any preceding claim, wherein the e-machine system further comprises a fluid coolant system (140) configured to provide pressurized fluid coolant to the stator member (119) and the rotor member (118), and wherein the sealing ring (150) is configured to seal against the pressurized fluid coolant to prevent passage thereof.

12. A vehicle (106) comprising the e-machine system of claim 11, wherein the e-machine (110) is an electric motor configured to provide propulsion to at least one wheel (104) of the vehicle.

13. A method of assembling an e-machine, the method comprising:providing (701) a rotor member including a groove;attaching (702) a sealing ring to the groove, the sealing ring being electrically conductive; andinstalling (703) the rotor member within a stator member, the stator member having a housing, such that the sealing ring contacts both a surface of the groove and a surface of the housing to form a fluid seal therebetween and such that a grounding path is formed from the rotor member to the housing via the sealing ring.

14. The method of claim 13, wherein the step of attaching (702) the sealing ring to the groove comprises forming an clearance fit between the sealing ring and the groove.

15. The method of claim 13 or 14, wherein the step of installing (703) the rotor member within the stator member comprises forming an interference fit between the sealing ring and a bore of the housing.

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