Connection device

Abstract

When electrically connecting a conductor and a rotating shaft, the scattering of powder generated at the contact points between the relative rotating members is suppressed. [Solution] The connecting device 1 electrically connects the housing 4 and the rotating shaft 2. The connecting device 1 includes a conductive shaft portion 10 attached to the rotating shaft 2 and having electrical conductivity, a brush unit 20 with one end in contact with the conductive shaft portion 10 and the other end attached to the housing 4, electrically connecting the conductive shaft portion 10 and the housing 4, and a sealing portion 30 attached to the brush unit 20 and extending from the brush unit 20 toward the conductive shaft portion 10.

Description

Technical Field

[0001] The present disclosure relates to a connecting device for electrically connecting a rotating shaft and a conductor.

Background Art

[0002] A rotating shaft driven by an electric motor may be charged. When the electric charge charged on this rotating shaft flows as an electric current to the bearing that supports the rotating shaft, electrical erosion may occur in the bearing. In order to prevent the flow of an electric current through the bearing, for example, Patent Document 1 describes that a brush unit is brought into contact with an end portion of the rotating shaft, and the electric charge charged on the rotating shaft is caused to flow to a conductor such as a housing via the brush unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the electrical connection portion between the conductor and the rotating shaft, the contact point on the rotating shaft side abuts against the contact point on the conductor side in a rotating state. Therefore, it is conceivable that powder is generated due to wear or the like in the abutting portion. If such powder enters the inside of a bearing provided around the rotating shaft or an engagement portion of a gear, etc., it is conceivable that problems will occur in these components.

[0005] For this reason, the present disclosure describes a connecting device capable of suppressing the scattering of powder generated at the abutting portion between members that rotate relative to each other when electrically connecting a conductor and a rotating shaft to the surroundings.

Means for Solving the Problems

[0006] A connecting device according to one aspect of the present disclosure is [1] "a connecting device for electrically connecting a rotating shaft and a conductor, comprising: a first conductive part attached to the end of the rotating shaft and having conductivity; a second conductive part having one end in contact with the first conductive part and the other end attached to the conductor, for electrically connecting the first conductive part and the conductor; and a sealing part attached to the second conductive part and extending from the second conductive part toward the first conductive part."

[0007] In this connection device, the contact area between the first conductive part and the second conductive part is surrounded by the first conductive part, the second conductive part, and the sealing part. As a result, the connection device can contain the powder generated at the contact area between the second conductive part, which is the contact point on the conductor side, and the first conductive part, which is the contact point on the rotating shaft side, within the space surrounded by the sealing part and so on. In this way, when electrically connecting a conductor and a rotating shaft, the connection device can suppress the scattering of powder (wear particles) generated at the contact area between the second conductive part on the conductor side and the first conductive part on the rotating shaft side, which rotate relative to each other.

[0008] The above-described connecting device may also be [2] "the connecting device according to [1] above, wherein the first conductive part has a recess, one end of the second conductive part is inserted into the recess of the first conductive part and abuts against the bottom of the recess, and the sealing part extends from the second conductive part toward the inner circumferential surface of the recess of the first conductive part." In this case, the connecting device can suppress the scattering of powder into the surroundings by using the sealing part that extends toward the inner circumferential surface of the recess of the first conductive part.

[0009] The above-described connecting device may also be [3] "the connecting device according to [1] above, wherein the sealing portion extends from the second conductive portion toward the surface of the first conductive portion that faces the second conductive portion in the direction of the rotation axis of the rotating shaft." In this case, the connecting device can suppress the scattering of powder into the surroundings by using a sealing portion that extends toward the surface of the outer surface of the first conductive portion that faces the second conductive portion in the direction of the rotation axis of the rotating shaft.

[0010] The above-described connecting device may also be [4] "the connecting device according to any one of [1] to [3] above, wherein the second conductive part has a conductive brush that abuts against the first conductive part, and a resin sleeve that holds the brush so as to be slidable in the direction of contact with the first conductive part, the sleeve has a sleeve extension portion that extends toward the first conductive part, and the sealing part is composed of the sleeve extension portion." In this case, the connecting device can make a part of the sleeve function as a sealing part. This allows the connecting device to simplify its structure while suppressing the scattering of powder into the surroundings.

[0011] A connecting device according to another aspect of the present disclosure is [5] "a connecting device for electrically connecting a rotating shaft and a conductor, comprising: a first conductive part attached to the end of the rotating shaft and having conductivity; a second conductive part having one end in contact with the first conductive part and the other end attached to the conductor, for electrically connecting the first conductive part and the conductor; and a sealing part attached to the first conductive part and extending from the first conductive part toward the second conductive part."

[0012] In this connection device, the contact area between the first conductive part and the second conductive part is surrounded by the first conductive part, the second conductive part, and the sealing part. As a result, the connection device can contain the powder generated at the contact area between the second conductive part, which is the contact point on the conductor side, and the first conductive part, which is the contact point on the rotating shaft side, within the space surrounded by the sealing part and so on. In this way, when electrically connecting a conductor and a rotating shaft, the connection device can suppress the scattering of powder (wear particles) generated at the contact area between the second conductive part on the conductor side and the first conductive part on the rotating shaft side, which rotate relative to each other.

[0013] The above-described connecting device may also be [6] "the connecting device according to [5] above, wherein the first conductive part has a recess, one end of the second conductive part is inserted into the recess of the first conductive part and abuts against the bottom of the recess, and the sealing part extends from the inner circumferential surface of the recess of the first conductive part toward the second conductive part." In this case, the connecting device can suppress the scattering of powder into the surroundings by using the sealing part that extends from the inner circumferential surface of the recess of the first conductive part toward the second conductive part.

[0014] The above-described connecting device may be [7] "the connecting device according to any one of [1] to [6] above, comprising: a holder attached to the conductor and having conductivity; a brush (the brush) in contact with the first conductive part and having conductivity; a biasing part that biases the brush toward the first conductive part; a cylindrical sleeve (the sleeve) attached to the holder, with the brush positioned inside and holding the brush so as to be slidable in the direction of biasing the brush by the biasing part; and a conductive part that electrically connects the brush and the holder." The connecting device can hold the brush with the sleeve while the biasing part can reliably bring the brush into contact with the first conductive part. As a result, the connecting device can more reliably maintain the electrical connection between the first conductive part and the second conductive part. [Effects of the Invention]

[0015] According to one aspect of this disclosure, when electrically connecting a conductor and a rotating shaft, it is possible to suppress the scattering of powder generated at the contact points between members that rotate relative to each other. [Brief explanation of the drawing]

[0016] [Figure 1] Figure 1 is a cross-sectional view of the rotation axis to which the connecting device according to the first embodiment is attached. [Figure 2] Figure 2 is an enlarged cross-sectional view of the connection device shown in Figure 1. [Figure 3] Figure 3 is an enlarged cross-sectional view of a first modified example of the connection device according to the first embodiment. [Figure 4] Figure 4 is an enlarged cross-sectional view of a second modification of the connection device according to the first embodiment. [Figure 5] Figure 5 is an enlarged cross-sectional view of a third modification of the connection device according to the first embodiment. [Figure 6] Figure 6 is an enlarged cross-sectional view of a modification of the third modification of the connection device according to the first embodiment. [Figure 7] Figure 7 is an enlarged cross-sectional view of a fourth modification of the connection device according to the first embodiment. [Figure 8] Figure 8 is an enlarged cross-sectional view of the connection device according to the second embodiment. [Figure 9] Figure 9 is an enlarged cross-sectional view of a modification of the connection device according to the second embodiment. [Figure 10] Figure 10 is an enlarged cross-sectional view of the connection device according to the third embodiment.

Mode for Carrying Out the Invention

[0017] Hereinafter, exemplary embodiments of the connection device according to the present disclosure will be described with reference to the drawings. In each figure, the same or corresponding elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[0018] (First Embodiment) First, the connection device according to the first embodiment will be described. As shown in FIG. 1, the connection device 1 electrically connects a rotating shaft 2 rotatably supported by a bearing 3 and a housing (conductor) 4. The rotating shaft 2 may be the shaft of an electric motor, or may be a shaft connected to the shaft of an electric motor via a gear. In the present embodiment, the portion on the end 2a side of the rotating shaft 2 has a hollow shaft (hollow structure). Note that the rotating shaft 2 may be a hollow shaft not only in the portion of the end 2a but also in the entire rotating shaft 2. The bearing 3 supports the rotating shaft 2 so as to be rotatable about the rotation axis L. The type of the bearing 3 is not particularly limited as long as it can support the rotating shaft 2 rotatably.

[0019] The housing 4 houses the connecting device 1, the rotating shaft 2, and the bearing 3, etc. The housing 4 is electrically conductive. In this embodiment, the connecting device 1 electrically connects the rotating shaft 2 and the housing 4, thereby forming a conductive path with a lower resistance than the conductive path from the rotating shaft 2 to the housing 4 via the bearing 3.

[0020] As shown in Figure 1, the connecting device 1 comprises a axial conductive part (first conductive part) 10, a brush unit (second conductive part) 20, and a sealing part 30. The axial conductive part 10 is conductive. The axial conductive part 10 also has a recess 10a. The axial conductive part 10 is attached to the end 2a of the rotating shaft 2 such that the opening 10b of the recess 10a faces outward.

[0021] More specifically, the axial conductive portion 10 comprises a ball holder 11 and a steel ball 12. The ball holder 11 and the steel ball 12 are both electrically conductive. The ball holder 11 has a shape with a recess 10a. The ball holder 11 is formed, for example, by press-forming a steel plate.

[0022] The steel ball 12 may be, for example, a ball used in a bearing. The steel ball 12 is attached to the bottom 10c of the recess 10a of the ball holder 11. Here, as an example, the steel ball 12 is fitted into a recess provided at the bottom 10c of the recess 10a of the ball holder 11 and fixed by crimping. In this way, the steel ball 12 is provided at the bottom 10c of the recess 10a in the axial conductive part 10 and constitutes a convex contact portion that abuts against the brush unit 20 (end face S of the brush 22). The steel ball 12 is attached to the ball holder 11 such that the center of the steel ball 12 is located on the rotation axis L, which is the rotation center of the rotation axis 2.

[0023] The outer circumferential surface of the ball holder 11 is provided with a fitting portion 11a that fits into and secures the inner circumferential surface 2b of the end portion 2a of the rotating shaft 2. The ball holder 11 is fitted into and secured to the inner circumferential surface 2b of the end portion 2a of the rotating shaft 2 such that the opening 10b of the recess 10a faces outward. The fitting portion 11a of the ball holder 11 and the inner circumferential surface 2b of the rotating shaft 2 are engaged with each other. Therefore, the ball holder 11 rotates integrally with the rotating shaft 2. The steel ball 12 contacts one end of the brush unit 20 (the end face S of the brush 22) within the recess 10a of the ball holder 11.

[0024] One end of the brush unit 20 (the end on the brush 22 side) is inserted into the recess 10a of the axial conductive part 10 and abuts against the bottom 10c of the recess 10a. In this embodiment, one end of the brush unit 20 abuts against the steel ball 12 provided at the bottom 10c of the recess 10a of the axial conductive part 10. The other end of the brush unit 20 is attached to the housing 4. In this way, the brush unit 20 is attached to the housing 4. The brush unit 20 abuts against the axial conductive part 10 provided on the rotating shaft 2, electrically connecting the housing 4 and the axial conductive part 10.

[0025] More specifically, as shown in Figure 2, the brush unit 20 comprises a holder 21, a brush 22, a spring (biasing part) 23, a sleeve 24, an electrode 25, and wiring 26.

[0026] The holder 21 is electrically conductive. As an example, a conductive metal (steel) can be used as the material for the holder 21. One end of the holder 21 is inserted into the recess 10a of the axial conductive part 10. The other end of the holder 21 is attached to the housing 4. In this embodiment, the housing 4 is provided with a recess 4a (see Figure 1) on the axis of rotation L, which is the rotation center of the rotating shaft 2. The holder 21 is attached to the housing 4 by fitting its other end into the recess 4a. As a result, the housing 4 and the holder 21 are electrically connected to each other.

[0027] More specifically, the holder 21 comprises a holder body portion 21a, a first protrusion portion 21b, and a second protrusion portion 21c. The holder body portion 21a is cylindrical. In this embodiment, the holder body portion 21a may be cylindrical in shape. The holder body portion 21a extends along the axis of rotation L (see Figure 1). The first protrusion portion 21b is provided at the end of the holder body portion 21a that is fitted into the recess 4a of the housing 4. The first protrusion portion 21b protrudes inward from the end of the holder body portion 21a. The first protrusion portion 21b may be provided so as to cover the entire opening at the end of the holder body portion 21a. The second protrusion portion 21c is provided at the end of the holder body portion 21a opposite to the side on which the first protrusion portion 21b is provided. The second protruding portion 21c extends inward from the end of the holder body portion 21a. The tip of the second protruding portion 21c forms an opening 21d that connects the inside and outside of the holder 21.

[0028] The brush 22 is conductive. The brush 22 is housed in the holder 21, and the end on the axial conductive portion 10 side protrudes from the holder 21 through the opening 21d of the holder 21. The brush 22 is held by the sleeve 24 and can slide along the axis of rotation L. As an example, a carbon brush can be used as the brush 22. In this embodiment, the brush 22 has a cylindrical shape with the axis of rotation L as its axis. However, the brush 22 is not limited to a cylindrical shape and may have a prismatic shape such as a square.

[0029] The brush 22 contacts the axial conductive portion 10. More specifically, the end face S of the brush 22 on the bottom 10c side (steel ball 12 side) of the recess 10a of the axial conductive portion 10 contacts the steel ball 12. In other words, the end face S becomes the contact surface that contacts the steel ball 12. The shape of the end face S may be flat, concave (for example, a shape that is recessed in an arc shape), or convex (for example, a shape that protrudes in an arc shape). In this embodiment, it is sufficient for the end face S to be able to make point contact with the steel ball 12.

[0030] As mentioned above, the steel ball 12 is positioned such that its center lies on the axis of rotation L. Therefore, the end face S of the brush 22 and the steel ball 12 make point contact with each other on the axis of rotation L. As a result, even when the axial conductive part 10 rotates together with the rotation axis 2, the contact point between the end face S of the brush 22 and the steel ball 12 does not shift position. In other words, the difference in peripheral speed between the end face S and the steel ball 12 at the contact point between them is zero.

[0031] The spring 23 is electrically conductive. For example, the spring 23 is a coil-shaped compression spring. The spring 23 biases the brush 22 toward the bottom 10c of the recess 10a of the axial conductive portion 10. In other words, the spring 23 biases the brush 22 toward the steel ball 12. As a result, the brush 22 makes point contact with the steel ball 12 when the connecting device 1 is attached. That is, the brush 22 and the steel ball 12 are electrically connected.

[0032] The sleeve 24 is housed within the holder 21. The material of the sleeve 24 may be resin or a conductive metal. The sleeve 24 is cylindrical. In this embodiment, the sleeve 24 is cylindrical. The brush 22 and spring 23 are arranged inside the sleeve 24. The sleeve 24 is cylindrical and extends in the direction of biasing the brush 22 by the spring 23. The sleeve 24 holds the brush 22 so as to be slidable in the direction of biasing the brush 22 by the spring 23.

[0033] The electrode 25 is conductive. The electrode 25 is housed in the holder 21 and is in contact with the first protrusion 21b of the holder 21. The electrode 25 has a protrusion 25a that projects toward the brush 22. The spring 23 is positioned between the electrode 25 and the brush 22. The end of the spring 23 is fitted onto the outside of the protrusion 25a. The protrusion 25a can be used to position the spring 23. The outer edge of the electrode 25 is sandwiched between the first protrusion 21b of the holder 21 and the sleeve 24 in the direction of biasing the brush 22 by the spring 23.

[0034] One end of the wiring 26 is connected to the electrode 25. The other end of the wiring 26 is connected to the brush 22. The wiring 26 electrically connects the electrode 25 and the brush 22. The wiring 26 is, for example, flexible. The wiring 26 maintains the electrically connected state between the electrode 25 and the brush 22 even if the distance between them changes.

[0035] The wiring 26 is routed inside the coiled spring 23. With both ends of the wiring 26 connected to the electrode 25 and the brush 22, the brush 22, spring 23, electrode 25, and wiring 26 are integrated with each other. This improves the ease of assembly when assembling the brush 22, spring 23, electrode 25, and wiring 26 to the holder 21 of the brush unit 20. Thus, in this embodiment, the electrode 25 and the wiring 26 constitute a conductive part that electrically connects the brush 22 and the holder 21.

[0036] The brush 22 is electrically connected to the electrode 25 by wiring 26. The electrode 25 is fixed to the holder 21 by being sandwiched between the first protruding portion 21b of the holder 21 and the sleeve 24. This prevents the brush 22 from falling out of the holder 21 and sleeve 24 when the steel ball 12 is not in contact with the brush 22 (for example, when assembling the brush unit 20 to the housing 4, and before assembling the brush unit 20).

[0037] The seal portion 30 is attached to the brush unit 20. The seal portion 30 extends from the brush unit 20 toward the surface of the shaft conductive portion 10 that faces the brush unit 20. The tip of the seal portion 30 is in slidable contact (almost in contact) with the surface of the shaft conductive portion 10 that faces the brush unit 20.

[0038] More specifically, the seal portion 30 is annular in shape. In this embodiment, the seal portion 30 is attached to the second protrusion 21c of the holder 21. The brush 22 passes inside the annular seal portion 30. The seal portion 30 extends from the second protrusion 21c (brush unit 20) toward the inner circumferential surface 10d of the recess 10a of the shaft conductive portion 10. The inner circumferential surface 10d of the shaft conductive portion 10 is a cylindrical surface. The outer edge of the seal portion 30 slidably abuts (almost abuts) against the inner circumferential surface 10d of the shaft conductive portion 10. As a result, the contact portion between the brush 22 and the steel ball 12 is surrounded by the shaft conductive portion 10, the brush unit 20, and the seal portion 30.

[0039] As an example, the seal portion 30 comprises a seal body portion 31 and a seal lip 32. The seal body portion 31 is annular in shape. For example, metal (steel) can be used as the material for the seal body portion 31. The seal lip 32 is provided on the outer edge of the seal body portion 31. The seal lip 32 slidably contacts the inner circumferential surface 10d of the shaft conductive portion 10. For example, an elastically deformable material such as rubber can be used as the material for the seal lip 32.

[0040] Next, the conductive path between the rotating shaft 2 and the housing 4 when the connecting device 1 is used will be described. In this embodiment, the ball holder 11, steel ball 12, holder 21, brush 22, electrode 25, and wiring 26 are conductive. Therefore, the rotating shaft 2 is electrically connected to the housing 4 via the ball holder 11, steel ball 12, brush 22, wiring 26, electrode 25, and holder 21. In other words, the brush unit 20, which includes the ball holder 11, steel ball 12, brush 22, wiring 26, electrode 25, and holder 21, is conductive and forms a conductive path that electrically connects the rotating shaft 2 and the housing 4. In addition, in this embodiment, the spring 23 is conductive. Therefore, the spring 23 can also form a conductive path between the brush 22 and the electrode 25. As a result, the rotating shaft 2 and the housing 4 are electrically connected even when the rotating shaft 2 is in a rotating state.

[0041] As described above, in the connecting device 1, the contact portion between the steel ball 12 of the axial conductive part 10 and the brush 22 of the brush unit 20 is surrounded by the axial conductive part 10, the brush unit 20, and the seal part 30. As a result, the connecting device 1 can contain the powder generated at the contact portion between the brush 22 of the brush unit 20, which is the contact point on the housing 4 side, and the steel ball 12 of the axial conductive part 10, which is the contact point on the rotating shaft 2 side, within the space surrounded by the seal part 30 and the like. In this way, when electrically connecting the housing 4 and the rotating shaft 2, the connecting device 1 can suppress the scattering of powder (wear particles) generated at the contact portion between the brush unit 20 on the housing 4 side and the axial conductive part 10 on the rotating shaft 2 side, which rotate relative to each other.

[0042] Furthermore, in the connection device 1, the seal portion 30 is attached to the brush unit 20, which is mounted on the housing 4, the fixed side. In other words, since the seal portion 30 does not rotate, it is not affected by centrifugal force. For this reason, in the connection device 1, the design of the seal portion 30 is simpler compared to the case where the seal portion is attached to the axial conductive portion 10 that rotates together with the rotating shaft 2.

[0043] The seal portion 30 is attached to the second protruding portion 21c of the holder 21. The seal portion 30 extends from the second protruding portion 21c toward the inner circumferential surface 10d of the recess 10a of the shaft conductive portion 10. In this case, the connecting device 1 can suppress the scattering of powder into the surroundings by using the seal portion 30 having such a configuration. Furthermore, the inner circumferential surface 10d of the recess 10a of the shaft conductive portion 10 has a cylindrical shape that extends along the rotation axis L direction (i.e., the direction in which the brush 22 and the steel ball 12 come into contact). Therefore, even if a misalignment occurs between the shaft conductive portion 10 and the brush unit 20 in the rotation axis L direction due to, for example, mounting errors, the seal lip 32 of the seal portion 30 can be brought into contact with the inner circumferential surface 10d of the shaft conductive portion 10 regardless of this misalignment.

[0044] The brush unit 20 of the connecting device 1 includes a spring 23 that biases the brush 22 and a sleeve 24 that slidably holds the brush 22. The connecting device 1 holds the brush 22 with the sleeve 24, and the spring 23 ensures that the brush 22 is in firm contact with the steel ball 12 of the axial conductive part 10. As a result, the connecting device 1 can maintain a more reliable electrical connection between the axial conductive part 10 and the brush unit 20.

[0045] (First embodiment, first modified example) A first modified example of the connection device according to the first embodiment will be described. In the various embodiments and modified examples described below, components similar to those in the connection device 1 according to the first embodiment will be denoted by the same reference numerals and their descriptions will be omitted. As shown in Figure 3, the connection device 1A according to this modified example is equipped with a seal portion 30A with a different configuration in place of the seal portion 30 of the connection device 1 according to the first embodiment. The seal portion 30A is attached to the second protruding portion 21c of the holder 21 of the brush unit 20. The seal portion 30A extends from the second protruding portion 21c toward the connection portion (concave corner) between the inner circumferential surface 10d and the bottom portion 10c of the recess 10a of the shaft conductive portion 10.

[0046] The outer edge of the sealing portion 30A slidably abuts (almost abuts) against the connection portion between the inner circumferential surface 10d and the bottom portion 10c of the shaft conductive portion 10. As a result, the contact portion between the brush 22 and the steel ball 12 is surrounded by the shaft conductive portion 10, the brush unit 20, and the sealing portion 30A. Even in this case, the connecting device 1A can achieve the same effects as the connecting device 1 according to the first embodiment.

[0047] (Second modified example of the first embodiment) A second modified example of the connection device according to the first embodiment will now be described. As shown in Figure 4, the connection device 1B according to this modified example is equipped with a seal portion 30B with a different configuration in place of the seal portion 30 of the connection device 1 according to the first embodiment. The seal portion 30B is attached to the second protrusion 21c of the holder 21 of the brush unit 20. The seal portion 30B extends from the second protrusion 21c toward the bottom 10c of the recess 10a of the axial conductive portion 10. In other words, the seal portion 30B extends from the second protrusion 21c of the brush unit 20 toward the surface (bottom 10c) of the axial conductive portion 10 (ball holder 11) that faces the brush unit 20 in the direction of the rotation axis L.

[0048] The outer edge of the seal portion 30B is in slidable contact (almost in contact) with the bottom portion 10c of the shaft conductive portion 10. As a result, the contact portion between the brush 22 and the steel ball 12 is surrounded by the shaft conductive portion 10, the brush unit 20, and the seal portion 30B.

[0049] In this case, the connecting device 1B can suppress the scattering of powder into the surroundings, similar to the connecting device 1 according to the first embodiment, by using a seal portion 30B that extends from the outer surface of the shaft conductive portion 10 toward the bottom portion 10c facing the brush unit 20 in the direction of the rotation axis L of the rotating shaft 2. Furthermore, in the connecting device 1B, the contact portion between the tip portion (seal lip 32) of the seal portion 30B and the bottom portion 10c of the shaft conductive portion 10 can be positioned closer to the rotation axis L. As a result, the connecting device 1B can reduce the sliding resistance when the seal lip 32 of the seal portion 30B and the bottom portion 10c of the shaft conductive portion 10 slide against each other. As a result, the connecting device 1B can suppress the scattering of powder into the surroundings while suppressing a decrease in the rotation efficiency of the rotating shaft 2.

[0050] (Third modified example of the first embodiment) A third modified example of the connection device according to the first embodiment will now be described. As shown in Figure 5, the connection device 1C according to this modified example is equipped with a seal portion 30C with a different configuration in place of the seal portion 30 of the connection device 1 according to the first embodiment. The seal portion 30C is attached to the outer circumferential surface of the holder body portion 21a of the holder 21 of the brush unit 20. The seal portion 30C extends from the outer circumferential surface of the holder body portion 21a toward the inner circumferential surface 10d of the recess 10a of the shaft conductive portion 10.

[0051] The outer edge of the sealing portion 30C is in slidable contact (almost in contact) with the inner circumferential surface 10d of the shaft conductive portion 10. As a result, the contact portion between the brush 22 and the steel ball 12 is surrounded by the shaft conductive portion 10, the brush unit 20, and the sealing portion 30C. Even in this case, the connecting device 1C can achieve the same effects as the connecting device 1 according to the first embodiment.

[0052] (A variation of the third variation of the first embodiment) A third modified example of the connection device according to the first embodiment will now be described. As shown in Figure 6, the connection device 1Ca according to this modified example is equipped with a seal portion 30Ca in place of the seal portion 30C of the connection device 1C shown in Figure 5. In addition, a recess 21h extending in the circumferential direction is provided on the outer circumferential surface of the holder body portion 21a. The seal portion 30Ca comprises an annular seal body portion 31Ca and a seal lip 32 provided on the outer edge of the seal body portion 31Ca. The seal portion 30Ca is attached to the outer circumferential surface of the holder body portion 21a by fitting the inner edge portion (inner peripheral edge portion) of the seal body portion 31Ca into the recess 21h of the holder body portion 21a. The seal portion 30Ca extends from the outer circumferential surface of the holder body portion 21a toward the inner circumferential surface 10d of the recess 10a of the shaft conductive portion 10.

[0053] The outer edge (seal lip 32) of the seal portion 30Ca is in slidable contact (almost in contact) with the inner circumferential surface 10d of the shaft conductive portion 10. As a result, the contact portion between the brush 22 and the steel ball 12 is surrounded by the shaft conductive portion 10, the brush unit 20, and the seal portion 30Ca. Even in this case, the connecting device 1Ca can achieve the same effects as the connecting device 1 according to the first embodiment. Furthermore, in the connecting device 1Ca, the seal portion 30Ca can be easily attached to the holder 21 by fitting the seal portion 30Ca into the recess 21h of the holder 21.

[0054] (Fourth modified example of the first embodiment) A fourth modified example of the connection device according to the first embodiment will now be described. As shown in Figure 7, the connection device 1D according to this modified example is equipped with a seal portion 30D with a different configuration in place of the seal portion 30 of the connection device 1 according to the first embodiment. The seal portion 30D is attached to the outer circumferential surface of the holder body portion 21a of the holder 21 of the brush unit 20. Here, the axial conductive portion 10 has an overhang portion 10e that protrudes radially outward at its outer edge. The overhang portion 10e abuts against the end face of the end 2a of the rotating shaft 2 when the axial conductive portion 10 is fitted into the inner circumferential surface 2b of the end 2a of the rotating shaft 2. For this reason, for example, the overhang portion 10e may function as a stopper that defines the fitting depth when the axial conductive portion 10 is fitted into the inner circumferential surface 2b of the end 2a of the rotating shaft 2. The seal portion 30D extends from the outer circumferential surface of the holder body portion 21a toward the overhang portion 10e of the axial conductive portion 10.

[0055] The outer edge of the sealing portion 30D is in slidable contact (almost in contact) with the protruding portion 10e of the axial conductive portion 10. As a result, the contact portion between the brush 22 and the steel ball 12 is surrounded by the axial conductive portion 10, the brush unit 20, and the sealing portion 30D. Even in this case, the connecting device 1D can achieve the same effects as the connecting device 1 according to the first embodiment.

[0056] (Second Embodiment) Next, a connection device according to the second embodiment will be described. As shown in Figure 8, the connection device 1E comprises a shaft conductive part 10 and a brush unit (second conductive part) 20E. The brush unit 20E is attached to the housing 4, similar to the brush unit 20 according to the first embodiment. The brush unit 20E contacts the shaft conductive part 10 (steel ball 12) provided on the rotating shaft 2, thereby electrically connecting the housing 4 and the shaft conductive part 10.

[0057] More specifically, the brush unit 20E comprises a holder 21E, a brush 22, a spring 23, a sleeve 24E, an electrode 25, and wiring 26. The holder 21E is conductive. The holder 21E has a concave shape. The holder 21E is attached to the housing 4 by being fitted into a recess 4a of the housing 4. This electrically connects the housing 4 and the holder 21E. The sleeve 24E is attached to the holder 21E. One end of the sleeve 24E is inserted into the inside of the recess of the holder 21E and fixed to the holder 21E. The holder 21E and the sleeve 24E may engage with each other by a protrusion 24a provided on the outer circumferential surface of the sleeve 24E being fitted into a groove 21e provided on the inner circumferential surface of the recess of the holder 21E. In this embodiment, the sleeve 24E is made of resin.

[0058] The sleeve 24E is cylindrical in shape. In this embodiment, the sleeve 24E is cylindrical in shape. The brush 22 and the spring 23 are arranged inside the sleeve 24E. The sleeve 24E is cylindrical in shape and extends in the direction in which the brush 22 is biased by the spring 23. The sleeve 24E holds the brush 22 so that it can slide in the direction in which the brush 22 is biased by the spring 23.

[0059] Furthermore, the sleeve 24E has a sleeve extension portion 24b that extends toward the bottom 10c of the recess 10a of the axial conductive portion 10. The tip of the sleeve extension portion 24b is in slidable contact (almost in contact) with the bottom 10c of the recess 10a of the axial conductive portion 10. As a result, the contact portion between the brush 22 and the steel ball 12 is surrounded by the axial conductive portion 10 and the brush unit 20E. In other words, the sleeve extension portion 24b is provided on the brush unit 20E and constitutes a sealing portion that extends from the brush unit 20E toward the brush unit 20E side (bottom 10c) of the axial conductive portion 10.

[0060] Even in this case, the connecting device 1E can achieve the same effects as the connecting device 1 according to the first embodiment. Furthermore, the connecting device 1E can make a part of the sleeve 24E (the sleeve extension portion 24b) function as a sealing portion. As a result, the connecting device 1E can simplify its configuration while suppressing the scattering of powder into the surroundings, similar to the connecting device 1 according to the first embodiment.

[0061] (Modified version of the second embodiment) A modified example of the connecting device according to the second embodiment will now be described. As shown in Figure 9, the connecting device 1F according to this modified example has a brush unit 20F equipped with a sleeve 24F of a different configuration, instead of the brush unit 20E equipped with the sleeve 24E of the connecting device 1E according to the second embodiment. The sleeve 24F is made of resin. The sleeve 24F has a sleeve extension portion 24c that extends toward the inner circumferential surface 10d of the recess 10a of the shaft conductive portion 10. The tip of the sleeve extension portion 24c is in slidable contact (almost in contact) with the inner circumferential surface 10d of the recess 10a of the shaft conductive portion 10. As a result, the contact portion between the brush 22 and the steel ball 12 is surrounded by the shaft conductive portion 10 and the brush unit 20F. In other words, the sleeve extension portion 24c is provided on the brush unit 20F and constitutes a sealing portion that extends from the brush unit 20F toward the brush unit 20F side surface (inner circumferential surface 10d) of the shaft conductive portion 10.

[0062] Even in this case, the connecting device 1F can function as a sealing portion with a part of the sleeve 24F (sleeve extension portion 24c), similar to the connecting device 1E according to the second embodiment. As a result, the connecting device 1F can simplify its configuration while suppressing the scattering of powder into the surroundings, similar to the connecting device 1E according to the second embodiment.

[0063] (Third embodiment) Next, a connection device according to the third embodiment will be described. As shown in Figure 10, the connection device 1G comprises a shaft conductive part 10, a brush unit 20, and a seal part 30G. The seal part 30G is attached to the shaft conductive part 10. The seal part 30G extends from the shaft conductive part 10 toward the brush unit 20. The tip of the seal part 30G is in slidable contact (almost in contact) with the outer surface of the holder 21 of the brush unit 20.

[0064] More specifically, the seal portion 30G is annular in shape. In this embodiment, the seal portion 30G is attached to the inner circumferential surface 10d of the recess 10a of the shaft conductive portion 10. A holder 21 that houses the brush 22 passes through the inside of the annular seal portion 30G. The seal portion 30G extends from the inner circumferential surface 10d of the recess 10a of the shaft conductive portion 10 toward the outer circumferential surface of the holder body portion 21a of the holder 21, as the outer surface of the holder 21. The outer circumferential surface of the holder body portion 21a is a cylindrical surface. The inner edge portion (seal lip 32) of the seal portion 30G slidably abuts (almost abuts) against the outer circumferential surface of the holder body portion 21a. As a result, the contact portion between the brush 22 and the steel ball 12 is surrounded by the shaft conductive portion 10, the brush unit 20, and the seal portion 30G.

[0065] The sealing portion 30G may extend from the inner circumferential surface 10d of the recess 10a of the shaft conductive portion 10 toward the second protruding portion 21c of the holder 21, as the outer surface of the holder 21. Even in this case, the contact portion between the brush 22 and the steel ball 12 is surrounded by the shaft conductive portion 10, the brush unit 20, and the sealing portion 30G.

[0066] As an example, the seal portion 30G comprises a seal body portion 31G and a seal lip 32. The seal body portion 31G is annular in shape. The seal lip 32 is provided on the inner edge of the seal body portion 31G. The seal lip 32 slidably contacts the outer surface of the holder 21 of the brush unit 20.

[0067] Even in this case, the connection device 1G can achieve the same effects as the connection device 1 according to the first embodiment.

[0068] Although embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments. For example, in the connecting device 1E according to the second embodiment, the sleeve extension portion 24b of the sleeve 24E may extend toward the connection portion between the inner circumferential surface 10d and the bottom portion 10c of the recess 10a of the shaft conductive portion 10, similar to the connecting device 1A according to the first modification of the first embodiment described with reference to Figure 3. Also, for example, the brush unit is not limited to the brush and holder being electrically connected by electrodes and wiring. The brush and holder may be electrically connected to each other by conductive portions of other configurations.

[0069] At least some of the embodiments and various modifications described above may be combined in any way. [Explanation of symbols]

[0070] 1, 1A~1G, 1Ca…Connecting device, 2…Rotating shaft, 4…Housing (conductor), 10…Shaft conductive part (first conductive part), 10a…Recess, 10c…Bottom, 10d…Inner circumferential surface, 20, 20E, 20F…Brush unit (second conductive part), 21, 21E…Holder, 22…Brush, 23…Spring (biasing part), 24, 24E, 24F…Sleeve, 25…Electrode (conductive part), 26…Wiring (conductive part), 24b, 24c…Sleeve extension part (seal part), 30, 30A~30D, 30Ca, 30G…Seal part, 31Ca, 31G…Seal body part.

Claims

1. A connecting device that electrically connects a rotating shaft and a conductor, A first conductive part, which is attached to the end of the rotating shaft and has conductivity, One end of the second conductive portion abuts against the first conductive portion, and the other end is attached to the conductor, thereby electrically connecting the first conductive portion and the conductor. A sealing portion attached to the second conductive portion and extending from the second conductive portion toward the first conductive portion, A connecting device equipped with the following features.

2. The first conductive portion has a recess, One end of the second conductive part is inserted into the recess of the first conductive part and abuts against the bottom of the recess. The connecting device according to claim 1, wherein the sealing portion extends from the second conductive portion toward the inner circumferential surface of the recess of the first conductive portion.

3. The connecting device according to claim 1, wherein the sealing portion extends from the second conductive portion toward the surface of the first conductive portion on the side of the second conductive portion that faces the second conductive portion in the direction of the rotation axis of the rotating shaft.

4. The second conductive part is, A brush that contacts the first conductive part and is conductive, A resin sleeve holds the brush so as to be slidable in the direction of contact with the first conductive part, It has, The sleeve has a sleeve extension portion that extends toward the first conductive portion, The connecting device according to any one of claims 1 to 3, wherein the sealing portion is formed by the sleeve extension portion.

5. A connecting device that electrically connects a rotating shaft and a conductor, A first conductive part, which is attached to the end of the rotating shaft and has conductivity, One end of the second conductive portion abuts against the first conductive portion, and the other end is attached to the conductor, thereby electrically connecting the first conductive portion and the conductor. A sealing portion attached to the first conductive portion and extending from the first conductive portion toward the second conductive portion, A connecting device equipped with the following features.

6. The first conductive portion has a recess, One end of the second conductive part is inserted into the recess of the first conductive part and abuts against the bottom of the recess. The connecting device according to claim 5, wherein the sealing portion extends from the inner circumferential surface of the recess of the first conductive portion toward the second conductive portion.

7. The second conductive part is, A holder that is attached to the aforementioned conductor and is conductive, A brush that contacts the first conductive part and is conductive, A biasing unit that biases the brush toward the first conductive part, A cylindrical sleeve is attached to the holder, the brush is positioned inside it, and the sleeve holds the brush so as to be slidable in the direction of biasing the brush by the biasing part, A conductive part electrically connects the brush and the holder, A connecting device according to any one of claims 1 to 3, 5, or 6, comprising:

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