Externally mountable conductive assembly with circular substrate

Abstract

A conductive assembly prevents current flow through a raceway of a bearing that rotatably couples a shaft with an outer member such that the shaft or the outer member is rotatable about a central axis, the outer member having an outer mounting surface spaced radially outward from a bore. The conductive assembly includes an annular substrate formed of a conductive material and having a body fully surrounding a centerline and two or more integral mounting lugs, the two or more integral mounting lugs extend radially outward from the body and are connectable with a mounting surface of the outer member to secure the conductive assembly to the outer member. An annular inner conductor is connected with the substrate and has an inner radial end engageable with the shaft such that a conductive path extends through the inner conductor and the substrate between the shaft and the outer member.

Description

Technical Field

[0001] The present invention relates to bearings, and more particularly to grounding devices for preventing electric current or electric charge from passing through a bearing. Background Art

[0002] Bearings used in electrical machinery such as motors, generators and similar devices may be damaged if an electric current or charge passes through the bearing, particularly if this is harmful to the bearing raceways. Devices such as grounding brushes have been developed to provide an alternative path for the current generated by the charge accumulated on the shaft, thereby preventing such current from passing through the bearing. These devices typically include an annular retainer having an outer rim that frictionally engages with a hole in a housing or hub at a location adjacent to the bearing, and a plurality of conductive fibers attached to the retainer and circumferentially spaced around the entire outer surface of the shaft to form a ring of relatively solid fibers. In this way, the current passes from the shaft through the fibers and retainer and into the housing.

[0003] However, a certain amount of axial space is required to mount the conductive assembly in the housing bore, particularly since the conductive assembly should be spaced at least a certain distance from the bearing to avoid any conductive fibers that are detached during use from entering and damaging the bearing. This space requirement reduces the axial compactness of the shaft and the housing / hub. Furthermore, the heat generated in the electric machine may result in differences in thermal expansion of the bearing, the bore and / or the conductive assembly. In this way, the retainer rim may disengage from the bore, causing the conductive assembly to shift axially or creating increased radial interference between the conductive fibers and the shaft, resulting in a significant increase in friction. Summary of the invention

[0004] In one aspect, the present invention is a conductive assembly for preventing current from flowing through a bearing raceway, the bearing having an inner race disposed about a shaft and an outer race disposed within a bore of an outer member, the shaft or the outer member being rotatable about a central axis passing through the shaft, and the outer member having a radial surface spaced radially outward from the shaft. The conductive assembly comprises an annular substrate formed of a conductive material, having a centerline, and comprising a body entirely encircling the centerline and at least two integral mounting lugs extending radially outward from the body. The at least two mounting lugs are connectable to the radial surface of the outer member to secure the conductive assembly to the outer member at a position spaced axially from the bearing. An annular inner conductor is connected to the substrate and has an inner radial end engageable with the shaft such that a conductive path extends between the shaft and the outer member through the inner conductor and the substrate. Preferably, the inner conductor comprises an annular conductive retainer arranged against and connected to the substrate and a plurality of conductive fibers spaced circumferentially around the center line, the conductive retainer having an outer radial end, an inner radial end and an annular channel extending radially outward from the inner radial end, each fiber having an outer radial end arranged in the channel of the retainer and at least one inner radial end engageable with the shaft, so that a conductive path extends between the shaft and the external member through the inner conductor and the substrate.

[0005] On the other hand, the present invention is a mechanical component, which includes: a shaft having a central axis; an external member having a hole and a radial surface, the shaft being arranged in the hole, and the radial surface being radially spaced outward from the shaft; a bearing having an inner ring arranged around the shaft and an outer ring arranged in the hole of the external member, the bearing rotatably connecting the shaft with the hole so that the shaft or the hole can rotate around the central axis; and a conductive component as described in the previous paragraph. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The foregoing summary of the invention and the detailed description of the preferred embodiments of the invention will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the invention, the presently preferred embodiments are shown in the accompanying drawings which are drawn to scale. However, it should be understood that the invention is not limited to the precise configurations and means shown. In the accompanying drawings:

[0007] Figure 1is a broken-away front plan view of a conductor assembly according to the present invention shown arranged about an axis and mounted to an external member;

[0008] Figure 2 is a broken away axial cross-sectional view of a conductor assembly shown disposed about a shaft, mounted to an external member and spaced apart from a bearing;

[0009] Figure 3 is a front plan view of a conductor assembly;

[0010] Figure 4 is a front perspective view of a conductor assembly;

[0011] Figure 5 is a rear perspective view of the conductor assembly;

[0012] Figure 6 is a front plan view of a substrate of a conductor assembly;

[0013] Figure 7 is a front plan view of a conductor of the conductor assembly;

[0014] Figure 8 is through Figure 3 an enlarged view of line 8-8;

[0015] Fig. 9 is through Figure 3 an enlarged view of line 9-9;

[0016] Fig.10 is a broken front plan view of a conductor assembly having an alternative configuration substrate including a keeper opening, the conductive assembly being arranged about an axis and mounted to an external member; and

[0017] Fig.11 is a front plan view of another alternative configuration of a base plate including three mounting lugs. DETAILED DESCRIPTION

[0018] Certain terms are used in the following description for convenience only and are not limiting. The words "interior", "inwardly" and "exteriorly", "outwardly" refer to directions toward and away from a designated centerline or geometric center of the element being described, respectively, and the specific meaning is obvious from the context of the specification. In addition, as used herein, the words "connect" and "couple" are each intended to include a direct connection between two components without any other components interposed and an indirect connection between the components with one or more other components interposed. The terms include the words specifically mentioned above, their derivatives, and words of similar meaning.

[0019] Referring now in detail to the drawings, wherein like numerals are used to refer to like elements throughout, Figures 1 to 11 The raceway R for preventing current from flowing through the bearing 1 is shown in FIG. I , R O The bearing 1 has an inner ring 2 arranged around a shaft 3, an outer ring 4 arranged in a hole 5 of an outer member 6, and a plurality of rolling elements 7 ( Figure 2 ). The rolling elements 7 are each simultaneously on the raceway R I , R O Roll on to rotatably couple the bearing rings 2 and 4. Thus, the bearing 1 rotatably couples the shaft 3 and the external member 6 so that the shaft 3 or the external member 6 can rotate around the central axis A passing through the shaft 3. C Rotation. In addition, the outer member ( / outer member) 6 can be a seat ( / housing), an axle (axle), a hub, etc., and has an outer mounting surface 8, which is preferably radial and radially spaced outward from the hole 5. The bearing 1, the shaft 3 and the outer member 6 are all components of a motor or other electric machine M (for example, a generator), or components of any other machine having a rotatable component that may accumulate charge or transport current. In any case, the conductive component 10 basically includes a conductive annular base plate 12 connected to the outer member 6 and an inner annular conductor 14 connected to the base plate 12 and engageable with the shaft 3. In this way, the conductive component 10 provides one or more conductive paths extending between the shaft 3 and the outer member 6 through the inner conductor 14 and the base plate 12, so that the charge or current is diverted without flowing through the raceway R I , R O , thus preventing damage to the raceway R I , R O and rolling elements 7.

[0020] More specifically, the annular substrate 12 is formed of a conductive material, preferably a conductive metal material, most preferably steel, but may also be formed of another metal material (such as aluminum or copper), a conductive polymer, graphite, etc. The substrate 12 has a center line L C , and includes a full circle around the center line L CThe inner conductor 14 includes a generally circular body 20 and at least two integral mounting lugs 22 extending radially outwardly from the body 20. Each mounting lug 22 can be connected to the radial mounting surface 8 of the outer member 6 to fix the conductive assembly 10 to the outer member 6 at a position axially spaced from the bearing 1. In addition, the inner conductor 14 has an outer radial end 14b connected to the substrate 12 and an inner radial end 14a that can be engaged with the outer surface 3a of the shaft 3. Preferably, as described in detail below, the conductor 14 is formed into a conductive "brush assembly" 38, which includes a plurality of circumferentially spaced conductive fibers 42 extending inwardly from substantially the entire perimeter of the inner radial end 14a of the conductor 14.

[0021] By making the substrate 12 and the connected conductor 14 each surround the center line L C , thereby surrounding the shaft 3, the conductor 14 engages almost the entire circumference of the shaft 3. In this way, the conductor 14 provides a conductive path for the accumulated charge on the shaft 3, which is more effectively distributed around the entire shaft circumference and essentially acts as a barrier to prevent foreign matter from entering the hole 5 of the outer member 6. In addition, by connecting the substrate 12 to the outer radial surface 8 of the outer member 6, the conductive assembly 10 avoids the thermal expansion problems of known conductive assemblies having an annular rim coupled to the inner surface of the hole. Specifically, thermal expansion either causes the rim to separate from the hole, thereby causing the conductive assembly to shift axially, or causes the inner end of the conductor to be pressed against the shaft with increased friction. In addition, by eliminating the amount of hole space required to install the conductive assembly 10, the axial length of the shaft 3 and the seat 6 can be reduced, thereby increasing the axial compactness of the particular machine M. The basic components and functions have been described above, and these and other elements of the conductive assembly of the present invention are described in more detail below.

[0022] refer to Figures 4 to 6 The plate body 20 is generally circular and has an inner radial end 20a and an opposite outer radial end 20b, the inner radial end 20a having an inner diameter ID and defining a central opening 21, the size of the central opening 21 being suitable for receiving the shaft 3 with a clearance. The body 20 also has a first axial end 20c and an opposite second axial end 20b, the first axial end 20c having a flat, continuous radial surface 21A, and the second axial end 20b having a flat, continuous radial surface 21B, defining an axial thickness t between the two axial ends 20c, 20d. A ( Figure 8). Each mounting lug 22 has an inner radial end 22a integral with the outer radial end 20b of the body 20, an outer radial end 22b radially outwardly spaced from the inner end 22a, a first axial end 22c, and a second axial end 22d. In addition, each mounting lug 22 is preferably a generally rectangular shape with a curved outer end 22b, but may have any other suitable shape.

[0023] Preferably, the base plate 12 is substantially thin and flat (except for the mounting tabs 30 described below), and is preferably formed from a flat, relatively thin metal blank in a stamping operation. Fig. 9 As shown, the first axial end 20c of the body 20 and the first axial end 22c of each mounting lug 22 are arranged in a first radial plane P1, and the second axial end 20b of the body and the second axial end of each mounting lug 22 are arranged in a second radial plane parallel to the first radial plane P1, thereby demonstrating the flatness of the plate 12. In addition, the plate 12 has an axial thickness t A , the axial thickness t A Substantially less than the axial thickness (not shown) of the conductive brush assembly 38. Although such a thin flat plate is presently preferred, the base plate 12 may be formed with a substantially greater thickness and / or the mounting lugs 22 may extend radially outwardly and axially relative to the body 20 and thus not be arranged in a common plane(s) with the body 20.

[0024] See also Figure 3 , Figure 6 and Fig.10 In a first configuration, the base plate 12 includes two mounting lugs 22 circumferentially spaced apart by an angle α, which preferably has a value of about one hundred and eighty degrees (180°), but may also include values ​​between ninety degrees (90°) and one hundred and eighty degrees (180°), and although not currently preferred, may even have values ​​less than ninety degrees. Fig.11 In the second illustrated configuration, the base plate 12 includes three mounting lugs 22 that are preferably evenly spaced and thus separated by an angle of approximately one hundred and twenty degrees (120°) in the circumferential direction (not shown). However, the base plate 12 may include only a single substantially larger mounting lug 22 that may extend around all or a majority of the circumference of the body 20, or may include four or more mounting lugs 22 (configuration not shown).

[0025] In addition, each of the mounting lugs 22 preferably includes a portion for receiving a fastener 23 ( Figure 1 and Fig.10) fastener opening 26, each fastener 23 can be engaged with the outer member 6 to connect the base plate 12 to the outer member 6. Preferably, each fastener 23 is threadedly engaged with a threaded opening (not shown) extending inwardly from the outer radial mounting surface 8. However, the mounting lugs 22 can be attached to the outer surface 8 by any other suitable means, such as by a separate clamping member attached to the outer member 6, by frictionally engaging an axial portion of the mounting lug 22 with a circumferential or axially transverse mounting surface 8, etc. (alternative options not shown).

[0026] In some applications, each mounting lug 22 also includes a locator opening 28, such as Fig.10 As shown, the locator openings 28 are used to receive locator pins 29 that can engage with the outer member 6. Each locator opening 28 is located at a distance from the center line L C The inner conductor 12 is provided at a predetermined radial distance RD such that when at least two locator pins 29 are each inserted into a separate one of the two locator openings 28 and engage with the outer member 6, preferably when engaging with a precisely located locator opening (not shown) extending inwardly from the mounting surface 8, a desired concentricity of the inner conductor 12 is established. In addition, each locator opening 28 is configured to receive one locator pin 29 with a locational interference fit, and each fastener opening 26 is configured to receive one fastener 23 with a locational clearance fit (or even a "looser" fit).

[0027] refer to Figures 4 to 6 , Figure 8 and Fig. 9 The base plate 12 preferably has a plurality of integral mounting tabs 30, each tab 30 extending axially from the body 20 and extending about the centerline L CCircumferentially spaced apart. Each mounting tab 30 engages with the inner conductor 14 to connect the conductor 14 to the substrate 12. More specifically, each mounting tab 30 has an axial portion 32 and a radial portion 34, the axial portion 32 extending from the outer radial end 20a of the annular plate 20, and the radial portion 34 axially spaced apart from the annular plate 20 and extending inwardly from the axial portion 25. In this way, the conductor 14 is sandwiched between the annular plate 20 and the radial portion 34 of each tab 24 in the axial direction. In the case where the preferred substrate 12 is formed by stamping a flat blank, each mounting tab 30 initially extends radially outward from the body 20 and is bent twice to surround the radial outer end 14b of the conductor 14. However, as another option, the substrate 12 or the conductive assembly 10 can be formed to attach the inner conductor 14 to the substrate 12 by any other suitable means, such as, for example, by attaching the conductor 14 to the plate body 20 through a separate clip member (clip members), by extending through the conductor 14 and the substrate 12 through a fastener, etc.

[0028] Reference now Figures 7 to 9 , the conductor 14 is preferably a conductive brush assembly 38, which includes an outer, annular conductive holder 40 and a plurality of conductive fibers 42, which extend radially inward from the annular holder 40 and are configured to engage with the shaft 3. Preferably, the fibers 42 are engaged with an interference (i.e., by bending of the fibers 22) of up to 5 millimeters (5 mm) in diameter. Each conductive fiber 22 is preferably formed of carbon, but alternatively may be formed of a metallic material (e.g., copper, aluminum), a conductive polymer material, or any other suitable material.

[0029] In addition, the annular conductive retainer 40 has a closed outer radial end 40a where the conductor outer radial end 14a is disposed, an open inner radial end 40b, an annular channel 44 extending radially outward from the inner radial end 40b, and two circumferential ends 41A, 41B. Preferably, the annular conductive retainer 40 is formed to include an outer bottom wall ( / outer base wall) 46 and a pair of side walls 48A, 48B extending radially inward from the bottom wall 46 and defining the circumferential channel 44. In addition, the annular retainer 40 is preferably formed of a conductive metal material, most preferably aluminum, but may also be formed of another metal material (such as steel or copper), a conductive polymer material, or any other conductive material.

[0030] In addition, a plurality of conductive fibers 42 are arranged around the center line L of the conductor 14. CCircumferentially spaced apart, and preferably evenly distributed along the entire arcuate perimeter (not shown) between the circumferential ends 41A, 41B of the annular retainer 40. Each conductive fiber 42 has an outer radial end 42a disposed in the channel 44 of the retainer 40 and at least one inner radial end 42b engageable with the shaft 3. Preferably, the annular conductor 14 also includes an annular conductive wire 50 disposed in the retainer channel 44. Each conductive fiber 42 is bent around the arcuate line 50 so that each fiber 42 has two inner radial ends 42b engageable with the shaft 3 and is generally U-shaped or V-shaped. Figure 7 As best shown, the two circumferential ends 41A, 41B are spaced apart to define a gap 43, and the gap 43 can be adjusted by relative displacement of the two circumferential ends 41A, 41B to adjust the inner diameter DC of the inner conductor 14, preferably before the conductor 14 is mounted to the substrate 12. Thus, a desired inner diameter DC of the conductor 14 can be established to fit a specific size (i.e., outer diameter) of the shaft 3.

[0031] Although conductor 14 preferably includes an annular retainer 40 and a plurality of conductive fibers 42, conductor 14 may be formed in any other suitable manner. For example, conductor 14 may be formed as an arc-shaped solid member (not shown) formed of a flexible, conductive polymer material, graphite, or another conductive material.

[0032] The above describes in detail representative non-limiting examples of the present invention with reference to the accompanying drawings. This detailed description is only intended to teach those skilled in the art further details for practicing the preferred aspects of the present teachings, and is not intended to limit the scope of the present invention.

[0033] In addition, the combination of features and steps disclosed in the above detailed description may not be necessary to practice the present invention in the broadest sense, but is only taught to specifically describe representative examples of the present invention. In addition, various features of the above representative examples and various independent claims and dependent claims can be combined in a manner that is not specifically and explicitly listed, thereby providing additional useful embodiments of the present teaching.

[0034] For the purpose of original written disclosure, and for the purpose of limiting the subject matter claimed, all features disclosed in the description and / or claims are intended to be disclosed separately and independently from the composition of features in the embodiments and / or claims. In addition, for the purpose of original written disclosure, and for the purpose of limiting the subject matter claimed, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity. The invention is not limited to the above-described embodiments and may vary within the scope of the claims.

Claims

1. A conductive assembly for preventing current from flowing through a raceway of a bearing, the bearing having an inner ring arranged around a shaft and an outer ring arranged in a hole of an external member, the shaft or the external member being rotatable around a central axis passing through the shaft, and the external member having an outer mounting surface spaced radially outwardly from the hole, the conductive assembly comprising: an annular base plate formed of an electrically conductive material, having a centerline and including a body completely surrounding the centerline and at least two integral mounting lugs extending radially outwardly from the body and connectable with a mounting surface of the outer member to secure the electrically conductive assembly to the outer member at a location axially spaced from the bearing; as well as An annular inner conductor is connected to the substrate and has an inner radial end engageable with the shaft such that an electrically conductive path extends between the shaft and the outer member through the inner conductor and the substrate.

2. The conductive component according to claim 1, characterized in that: The plate body has a first axial end and a second axial end, each of the at least two mounting lugs has a first axial end and a second axial end, the first axial end of the body and the first axial end of each mounting lug are arranged in a first radial plane, and the second axial end of the body and the second axial end of each mounting lug are arranged in a second radial plane.

3. The conductive component according to claim 2, characterized in that: Each of the first and second axial ends of the plate body has a flat radial surface, and at least a portion of the inner conductor is disposed against the flat radial surface of one of the first and second axial ends.

4. The conductive component according to claim 1, characterized in that: The at least two mounting lugs are circumferentially spaced apart by an angle about a centerline of the base plate, the angle having a value of about 180 degrees or a value of about 120 degrees.

5. The conductive component according to claim 1, characterized in that: The annular plate has a plurality of integral mounting tabs, each tab extending axially from the body and spaced circumferentially about the centerline, each tab engaging the inner conductor to connect the conductor to the substrate.

6. The conductive component according to claim 1, characterized in that: The inner conductor comprises: an annular conductive retainer disposed against the base plate and having an outer radial end, an inner radial end, and an annular channel extending radially outward from the inner radial end; and A plurality of electrically conductive fibers are circumferentially spaced about the centerline, each fiber having an outer radial end disposed within the channel of the retainer and at least one inner radial end engageable with the shaft.

7. The conductive component according to claim 6, characterized in that: The inner radial ends of all the conductive fibers collectively define an inner diameter of the inner conductor; and The conductive holder has two circumferential ends spaced apart to define a gap, and the gap can be adjusted by relative displacement of the two circumferential ends of the holder so as to adjust the inner diameter of the inner conductor.

8. The conductive component according to claim 6, characterized in that: The conductor further comprises an annular wire disposed within the channel of the conductive holder, and each conductive fiber is bent about the arcuate wire so that each fiber has two inner radial ends capable of engaging with the shaft or the bearing inner ring.

9. The conductive component according to claim 1, characterized in that: Also included are two fasteners, and wherein each of the at least two mounting tabs includes a fastener opening for receiving a separate one of the two fasteners, each fastener being engageable with the outer member to connect the base plate to the outer member.

10. The conductive component according to claim 9, characterized in that: Also included are two locator pins, and wherein each of the at least two mounting lugs further includes a locator opening for receiving a locator pin capable of engaging with the outer member, each locator opening being positioned at a predetermined radial distance from the centerline so that when the two locator pins are each inserted into a separate one of the two locator openings and engaged with the outer member, a desired concentricity of the inner conductor is established, each locator opening being configured to receive a locator pin with an interference fit in position, and each fastener opening being configured to receive a fastener with a clearance fit in position.

11. A conductive assembly for preventing current from flowing through a raceway of a bearing, the bearing having an inner ring arranged around a shaft and an outer ring arranged in a bore of an external member, the shaft or the external member being rotatable about a central axis passing through the shaft, the external member having an outer mounting surface spaced radially outwardly from the bore, the conductive assembly comprising: an annular base plate formed of an electrically conductive material, having a centerline and including a body completely surrounding the centerline and at least two integral mounting lugs extending radially outwardly from the body and connectable with a mounting surface of the outer member to secure the electrically conductive assembly to the outer member at a location axially spaced from the bearing; as well as an inner annular conductor comprising an annular conductive holder disposed against and connected to the substrate and a plurality of conductive fibers spaced circumferentially about the centerline, the conductive holder having an outer radial end, an inner radial end, and an annular channel extending radially outward from the inner radial end, each fiber having an outer radial end disposed within the channel of the holder and at least one inner radial end engageable with the shaft such that a conductive path extends through the inner conductor and the substrate between the shaft and the outer member.

12. The conductive component according to claim 11, characterized in that: The inner radial ends of all conductive fibers collectively define an inner diameter of the inner conductor; and The conductive holder has two circumferential ends spaced apart to define a gap, and the gap can be adjusted by relative displacement of the two circumferential ends of the holder so as to adjust the inner diameter of the inner conductor.

13. The conductive component according to claim 12, characterized in that: The conductor further comprises an annular wire disposed within the channel of the conductive holder, and each conductive fiber is bent about the arcuate wire so that each fiber has two inner radial ends capable of engaging with the shaft or the bearing inner ring.

14. The conductive component according to claim 11, characterized in that: The plate body has a first axial end and a second axial end, each of the at least two mounting lugs has a first axial end and a second axial end, the first axial end of the body and the first axial end of each mounting lug are arranged in a first radial plane, and the second axial end of the body and the second axial end of each mounting lug are arranged in a second radial plane.

15. The conductive component according to claim 11, characterized in that: The at least two mounting lugs are circumferentially spaced apart by an angle about a centerline of the base plate, the angle having a value of about 180 degrees or a value greater than 90 degrees and less than 180 degrees.

16. The conductive component according to claim 11, characterized in that: The annular plate also includes a plurality of integral mounting tabs, each tab extending axially from the body and spaced circumferentially about the centerline, each tab engaging the inner conductor to connect the conductor to the substrate.

17. The conductive component according to claim 11, characterized in that: It also includes two fasteners and two locating pins, and wherein each of the at least two mounting lugs includes a fastener opening and a locating opening, the fastener opening being used to receive a separate one of the two fasteners, each fastener being capable of engaging with the external component to connect the substrate to the external component, the locating opening being used to receive a separate one of the locating pins, each locating pin being capable of engaging with the external component, each locating opening being positioned at a predetermined radial distance from the center line, so that when the two locating pins are each inserted into a separate one of the two locating openings and engaged with the external component, the desired concentricity of the inner conductor is established, each locating opening being constructed to receive a locating pin with an interference fit in position, and each fastener opening being constructed to receive a fastener with a clearance fit in position.

18. A mechanical assembly comprising: A shaft having a central axis; an outer member having a bore, the shaft being disposed within the bore and an outer mounting surface spaced radially outwardly from the bore; a bearing having an inner race disposed about the shaft and an outer race disposed within the bore of the outer member, the bearing rotatably coupling the shaft with the bore so that the shaft or the bore can rotate about the central axis; as well as A conductive assembly for preventing current from flowing through the bearing and comprising: an annular base plate formed of an electrically conductive material, having a centerline and including a body completely surrounding the centerline and at least two integral mounting lugs extending radially outwardly from the body and connectable with a mounting surface of the outer member to secure the electrically conductive assembly to the outer member at a location axially spaced from the bearing; as well as An annular inner conductor is connected to the substrate and has an inner radial end engageable with the shaft such that an electrically conductive path extends between the shaft and the outer member through the inner conductor and the substrate.

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