Brush unit and connection device

Abstract

This brush unit is brought into contact with a shaft conductive part provided on a rotating shaft to electrically connect a housing and the shaft conductive part. The brush unit is provided with: a holder; a brush that is brought into contact with the shaft conductive part via a first opening provided in the holder; a spring; a cylindrical sleeve that holds the brush; an electrode; and wiring that connects the brush and the electrode. The electrode is sandwiched between a second protruding part of the holder and the sleeve.

Description

Brush unit and connecting device

[0001] The present disclosure relates to a brush unit of a connection device that electrically connects a rotating shaft and an electric conductor, and to the connection device.

[0002] A rotating shaft driven by an electric motor can become electrically charged. This charge on the rotating shaft can flow as a current through a bearing that supports the rotating shaft, which can cause electrolytic corrosion in the bearing. Patent Document 1, for example, describes a method in which a brush unit is attached to the end of the rotating shaft to prevent current from flowing through the bearing. The electric charge on the rotating shaft is then passed through the brush unit to a conductor such as a housing.

[0003] Patent No. 6242566

[0004] Patent Document 1 does not describe in detail the configuration of the brush unit that passes current from the rotating shaft to the conductor. Therefore, in this technical field, there is a need for a brush unit that can ensure a stable conductive path with higher conductivity, and a connection device that includes this brush unit.

[0005] The brush unit according to the present disclosure is [1] "a brush unit attached to a conductor and abutting against a shaft conductive part provided on a rotating shaft to electrically connect the conductor and the shaft conductive part, comprising: a holder attached to the conductor, which is conductive, and which has an accommodation space provided therein; a conductive brush housed in the accommodation space and abutting against the shaft conductive part through a first opening provided in the holder; a biasing part which biases the brush towards the first opening; and a cylindrical sleeve housed in the accommodation space, inside which the brush is disposed and which holds the brush slidably in the biasing direction of the brush by the biasing part. a brush unit comprising: a conductive electrode; and wiring connecting the brush and the electrode; the holder having a cylindrical shape that is arranged to surround the sleeve and extends in the direction in which the brush is urged by the urging portion, the holder having a holder main body with one end opening of the cylindrical shape as the first opening; and a second protruding portion that protrudes inward from a second opening on the opposite side of the holder main body to the first opening, the second protruding portion facing the end face of the sleeve on the second opening side in the direction in which the brush is urged by the urging portion, the electrode being sandwiched between the second protruding portion and the sleeve.

[0006] In this brush unit, the holder attached to the conductor and the brush abutting on the shaft conductive portion attached to the rotating shaft are electrically connected to each other via wiring and electrodes. The electrodes are sandwiched between the second protruding portion of the holder and the sleeve. This ensures a stable electrical connection between the electrodes and the holder. In this way, the brush unit can ensure a stable conductive path with higher conductivity.

[0007] The brush unit according to the present disclosure may be [2] "the brush unit described in [1] above, wherein the holder further has a first protruding portion protruding inward from the first opening in the holder main body, the first protruding portion facing the end face of the sleeve on the first opening side in the direction of the biasing of the brush by the biasing portion, and the sleeve and the electrode are sandwiched between the first protruding portion and the second protruding portion." In this case, the electrode is more reliably electrically connected to the holder by being sandwiched together with the sleeve between the first protruding portion and the second protruding portion.

[0008] The brush unit according to the present disclosure may be [3] "the brush unit described in [2] above, wherein a first oil passage hole is provided in the first protruding portion, a second oil passage hole is provided in the second protruding portion, and a sleeve oil passage hole extending in the direction of biasing of the brush by the biasing portion is provided in a portion of the sleeve between the inner circumferential surface and the outer circumferential surface." In this case, in the brush unit, the first oil passage hole, the sleeve oil passage hole, and the second oil passage hole form an oil passage connecting the conductor and the rotating shaft. In this way, the brush unit can also be used as an oil passage for flowing oil such as lubricating oil between the conductor and the rotating shaft.

[0009] The brush unit according to the present disclosure may be [4] "the brush unit described in [1] above, wherein the holder main body has a holder oil passage hole connecting the outer peripheral surface and the inner peripheral surface of the holder main body, and the outer peripheral surface of the sleeve has an outer oil passage groove extending in the direction of the biasing of the brush by the biasing portion." In this case, in the brush unit, the holder oil passage hole and the outer oil passage groove form an oil passage connecting the conductor and the rotating shaft. Note that at the end of the holder on the first opening side, oil passes through the gap between the outer peripheral surface of the brush and the holder. In this way, the brush unit can also be used as an oil passage for flowing oil such as lubricant between the conductor and the rotating shaft.

[0010] The brush unit according to the present disclosure may be [5] "the brush unit described in [1] above, wherein the holder main body has a holder oil passage hole connecting the outer peripheral surface and the inner peripheral surface of the holder main body, the inner peripheral surface of the sleeve has an inner oil passage groove extending in the direction of the biasing of the brush by the biasing portion, and the sleeve has an inlet oil passage hole connecting the outer peripheral surface of the sleeve and the inner oil passage groove." In this case, in the brush unit, the holder oil passage hole, the inlet oil passage hole, and the inner oil passage groove form an oil passage connecting the conductor and the rotating shaft. Note that at the end of the holder on the first opening side, oil passes through the gap between the outer peripheral surface of the brush and the holder. In this way, the brush unit can also be used as an oil passage for flowing oil such as lubricant between the conductor and the rotating shaft.

[0011] The brush unit according to the present disclosure may be [6] "the brush unit according to any one of [1] to [5] above, wherein the electrode is elastically deformable in the sandwiching direction between the second protrusion and the sleeve, and is sandwiched in a compressed state between the second protrusion and the sleeve." In this case, the electrode biases the second protrusion of the holder by a force that causes the electrode to return to its original shape. This improves contact between the electrode and the holder in the brush unit, enabling a more stable electrical connection between the electrode and the second protrusion of the holder.

[0012] The brush unit according to the present disclosure may be [7] "the brush unit according to any one of [1] to [6] above, wherein the outer edge of the electrode is sandwiched between the holder main body and the second protruding portion at a corner where the holder main body and the second protruding portion are connected to each other." This allows the brush unit to more firmly fix the electrode by sandwiching the outer edge of the electrode. Therefore, the brush unit can more stably electrically connect the electrode and the holder.

[0013] The connection device according to the present disclosure is [8] "a connection device that electrically connects a rotating shaft and a conductor, comprising: a axial conductive part that is attached to the end of the rotating shaft and has conductivity; and a brush unit according to any one of [1] to [7] above, one end of which abuts the axial conductive part and the other end of which is attached to the conductor, electrically connecting the axial conductive part and the conductor."

[0014] This connection device includes the brush unit described above, and therefore, the connection device can ensure a stable conductive path with higher conductivity as described above.

[0015] According to the present disclosure, a stable conductive path with higher conductivity can be ensured.

[0016] FIG. 1 is a cross-sectional view around a rotation axis to which a connecting device is attached. FIG. 2(a) is an enlarged cross-sectional view of the brush unit of FIG. 1. FIG. 2(b) is an enlarged cross-sectional view showing a state before processing of a holder of the brush unit. FIG. 3 is an exploded perspective view of the brush unit of FIG. 1. FIG. 4 is a cross-sectional view of a brush unit according to a first modified example. FIG. 5 is an exploded perspective view of a brush unit according to the first modified example. FIG. 6 is a cross-sectional view of a brush unit according to a second modified example. FIG. 7 is an exploded perspective view of a brush unit according to the second modified example. FIG. 8 is a cross-sectional view of a brush unit according to a third modified example. FIG. 9 is an exploded perspective view of a brush unit according to the third modified example. FIG. 10 is a cross-sectional view of a brush unit according to a fourth modified example. FIG. 11 is a cross-sectional view of a brush unit according to a fifth modified example.

[0017] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and redundant description will be omitted.

[0018] As shown in FIG. 1 , the connection device 1 electrically connects a rotating shaft 2 rotatably supported by a bearing 3 to 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 this embodiment, the portion of the rotating shaft 2 on the end 2 a side is a hollow shaft (hollow structure). Note that the entire rotating shaft 2 may be a hollow shaft, not just the end 2 a portion. The bearing 3 supports the rotating shaft 2 rotatably about the rotation axis L. There is no particular limitation on the type of bearing 3 as long as it can rotatably support the rotating shaft 2.

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

[0020] As shown in Fig. 1, the connection device 1 includes a shaft conductive part 10 and a brush unit 20. The shaft conductive part 10 is electrically conductive. The shaft conductive part 10 has a shape with a recess 10a. The shaft conductive part 10 is attached to the end 2a of the rotating shaft 2 so that the opening 10b of the recess 10a faces outward.

[0021] More specifically, the axial conductive portion 10 includes 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 pressing 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 hole provided in 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 shaft conductive part 10, and forms a convex abutment part that abuts against the brush unit 20 (end surface S of the brush 22). The steel ball 12 is attached to the ball holder 11 so that the center of the steel ball 12 is located on the rotation axis L, which is the rotation center of the rotating shaft 2.

[0023] The outer peripheral surface of the ball holder 11 is provided with a fitting portion 11a that is fitted into and fixed to the inner peripheral surface 2b of the end 2a of the rotating shaft 2. The ball holder 11 is fitted into and fixed to the inner peripheral surface 2b of the end 2a of the rotating shaft 2 so that the opening 10b of the recess 10a faces outward. The fitting portion 11a of the ball holder 11 and the inner peripheral 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 abuts against one end of the brush unit 20 (end surface S of the brush 22) within the recess 10a of the ball holder 11.

[0024] One end of the brush unit 20 is inserted into the recess 10a of the shaft conductive part 10 and abuts against a steel ball 12 provided on the bottom 10c of the recess 10a. The other end of the brush unit 20 is attached to the housing 4. The brush unit 20 electrically connects the shaft conductive part 10 attached to the rotating shaft 2 to the housing 4. More specifically, as shown in Figures 2(a) and 3, the brush unit 20 includes a holder 21, brushes 22, a spring (biasing part) 23, a sleeve 24, an electrode 25, and wiring 26.

[0025] The holder 21 is electrically conductive. As an example of a material for the holder 21, a conductive metal (steel) can be used. An accommodation space R is provided inside the holder 21. A first opening H21a is provided in the holder 21. The end of the holder 21 on the side where the first opening H21a is provided is inserted into the recess 10a of the shaft conductive portion 10. The other end of the holder 21 is attached to the housing 4. In this embodiment, the housing 4 has a recess 4a (see FIG. 1 ) on the rotation axis L, which is the rotation center of the rotating shaft 2. The holder 21 is attached to the housing 4 by fitting the other end into the recess 4a. As a result, the housing 4 and the holder 21 are electrically connected to each other.

[0026] The brush 22 is accommodated in the accommodation space R of the holder 21. The brush 22 is electrically conductive. The brush 22 can slide along the rotation axis L within the holder 21. 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 rotation axis 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. By making the brush 22 shaped like a pillar, the brush 22 can be easily formed.

[0027] The brush 22 abuts against the axial conductive part 10 through a first opening H21a provided in the holder 21. More specifically, an end face S of the brush 22 on the side of the bottom 10c of the recess 10a of the axial conductive part 10 (the side facing the steel ball 12) abuts against the steel ball 12. In other words, the end face S serves as the abutment surface that abuts against the steel ball 12. The shape of the end face S may be flat, concave (for example, a shape recessed in an arc), or convex (for example, a shape protruding in an arc). In this embodiment, it is sufficient that the end face S can make point contact with the steel ball 12.

[0028] As described above, the steel balls 12 are arranged so that their centers are located on the rotation axis L. Therefore, the end faces S of the brushes 22 and the steel balls 12 are in point contact with each other on the rotation axis L. As a result, even when the shaft conductive part 10 rotates together with the rotating shaft 2, the contact points between the end faces S of the brushes 22 and the steel balls 12 do not shift position. In other words, the difference in peripheral speed between the end faces S and the steel balls 12 is zero at the connection portion between them.

[0029] The spring 23 is accommodated within the accommodation space R. The spring 23 is conductive. For example, the spring 23 is a coil-shaped compression spring. The spring 23 urges the brush 22 toward the first opening H21a of the holder 21. In other words, the spring 23 urges the brush 22 in a direction in which the brush 22 approaches the steel ball 12. As a result, the brush 22 comes into point contact with the steel ball 12 when the connection device 1 is attached. In other words, the brush 22 and the steel ball 12 are electrically connected.

[0030] The sleeve 24 is accommodated within the accommodation space R. The material of the sleeve 24 may be resin or a conductive metal. The sleeve 24 has a cylindrical shape. In this embodiment, the sleeve 24 has a cylindrical shape. The brush 22 and the spring 23 are disposed inside the sleeve 24. The sleeve 24 extends in the direction in which the spring 23 urges the brush 22. The sleeve 24 holds the brush 22 so as to be slidable in the direction in which the spring 23 urges the brush 22.

[0031] Here, the holder 21 has a first protruding portion 21a, a second protruding portion 21b, and a holder main body portion 21c. The holder main body portion 21c is arranged to surround the sleeve 24. The holder main body portion 21c has a tubular shape extending in the direction in which the spring 23 biases the brush 22. In this embodiment, the holder main body portion 21c has a cylindrical shape. In other words, the sleeve 24 is disposed inside the holder main body portion 21c. One end opening of the cylindrical holder main body portion 21c becomes the first opening H21a. The end opening of the holder main body portion 21c opposite the first opening H21a becomes the second opening H21b.

[0032] The first protruding portion 21a protrudes inward from the first opening H21a of the holder main body 21c. A predetermined gap is provided between the tip of the first protruding portion 21a in the protruding direction and the outer peripheral surface of the brush 22. The first protruding portion 21a faces the end face of the sleeve 24 on the first opening H21a side in the direction in which the spring 23 biases the brush 22.

[0033] The second protruding portion 21b protrudes inward from the second opening H21b of the holder main body 21c. The second protruding portion 21b faces the end face of the sleeve 24 on the second opening H21b side in the direction in which the spring 23 biases the brush 22.

[0034] The electrode 25 is electrically conductive. The electrode 25 is housed in the housing space R and abuts against the second protruding portion 21b. The electrode 25 has a protrusion 25a that protrudes toward the brush 22. The spring 23 is disposed between the electrode 25 and the brush 22. An end of the spring 23 is fitted onto the outside of the protrusion 25a. The protrusion 25a can determine the position of the spring 23.

[0035] The electrode 25 has an outer diameter larger than the inner hole of the sleeve 24. The outer edge of the electrode 25 is sandwiched between the second protruding portion 21b of the holder 21 and the sleeve 24 in the direction in which the spring 23 urges the brush 22. In this embodiment, the sleeve 24 and the electrode 25 are sandwiched between the first protruding portion 21a and the second protruding portion 21b of the holder 21 in the direction in which the spring 23 urges the brush 22.

[0036] 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 has, for example, flexibility. The wiring 26 maintains the state in which the electrode 25 and the brush 22 are electrically connected, even if the distance between the electrode 25 and the brush 22 changes.

[0037] The wiring 26 is passed through the inside of the coil-shaped spring 23. With both ends of the wiring 26 connected to the electrode 25 and the brush 22, respectively, the brush 22, the spring 23, the electrode 25, and the wiring 26 are integrated with one another. This improves the ease of assembly of the brush unit 20 when assembling the brush 22, the spring 23, the electrode 25, and the wiring 26 to the holder 21.

[0038] The brush 22 is connected to the electrode 25 by a wiring 26. The electrode 25 is fixed to the holder 21 by being sandwiched between the second protruding portion 21b and the sleeve 24. This prevents the brush 22 from falling off the holder 21 when the steel balls 12 are not in contact with the brush 22 (for example, when the brush unit 20 is being assembled to the housing 4, or before the brush unit 20 is assembled).

[0039] As shown in Figure 2 (b), the second protrusion 21b may be formed by bending (e.g., hot curling) the end 21d (the part that will become the second protrusion 21b) of the holder main body 21c while each component is accommodated within the accommodation space R of the holder 21.

[0040] Furthermore, the electrode 25 is configured to be elastically deformable in the sandwiching direction between the second overhanging portion 21b and the sleeve 24. The electrode 25 is sandwiched between the second overhanging portion 21b and the sleeve 24 in a compressed state. For example, the state shown in FIG. 2( b) is a state in which the electrode 25 is not sandwiched between the second overhanging portion 21b and the sleeve 24. As shown in FIG. 2( b), as an example of a configuration that is elastically deformable in the sandwiching direction, the portion of the electrode 25 sandwiched between the second overhanging portion 21b and the sleeve 24 may be inclined or curved with respect to the end surface of the sleeve 24. When the second overhanging portion 21b is formed by bending, the inclined or curved portion of the electrode 25 is pressed against the end surface of the sleeve 24, compressing the electrode 25 and sandwiching the electrode 25 between the second overhanging portion 21b and the sleeve 24.

[0041] In the present embodiment, the second protrusion 21b extends over the entire circumferential area of ​​the end of the holder main body 21c. That is, the second protrusion 21b has an annular shape. However, the present invention is not limited to this, and one or more second protrusions 21b may be provided intermittently along the circumferential direction of the second opening H21b of the holder main body 21c. Similarly, the first protrusion 21a is not limited to being annular. One or more first protrusions 21a may be provided intermittently along the circumferential direction of the first opening H21a of the holder main body 21c.

[0042] Next, the conductive path between the rotating shaft 2 and the housing 4 when the connection device 1 is used will be described. In this embodiment, the ball holder 11, the steel ball 12, the holder 21, the brush 22, the electrode 25, and the wiring 26 are conductive. Therefore, the rotating shaft 2 is electrically connected to the housing 4 via the ball holder 11, the steel ball 12, the brush 22, the wiring 26, the electrode 25, and the holder 21. In other words, the ball holder 11, the steel ball 12, the brush 22, the wiring 26, the electrode 25, and the holder 21 form a conductive path electrically connecting the rotating shaft 2 and the housing 4. Furthermore, 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 rotating.

[0043] As described above, in this brush unit 20, the holder 21 attached to the housing 4 and the brush 22 abutting against the shaft conductive portion 10 attached to the rotating shaft 2 are electrically connected to each other via the wiring 26 and the electrode 25. In addition, the electrode 25 is sandwiched between the second protruding portion 21b of the holder 21 and the sleeve 24. This ensures a stable electrical connection between the electrode 25 and the wiring 26. In this way, the brush unit 20 and the connection device 1 including this brush unit 20 can ensure a stable conductive path with higher conductivity.

[0044] The holder 21 has a first protruding portion 21a protruding inward from a first opening H21a in the holder main body 21c, and a second protruding portion 21b protruding inward from a second opening H21b in the holder main body 21c. The sleeve 24 and the electrode 25 are sandwiched between the first protruding portion 21a and the second protruding portion 21b. In this case, the electrode 25 is more reliably electrically connected to the sleeve 24 by being sandwiched together with the sleeve 24 between the first protruding portion 21a and the second protruding portion 21b.

[0045] The electrode 25 is sandwiched in a compressed state between the second protruding portion 21b and the sleeve 24. In this case, the electrode 25 biases the second protruding portion 21b of the holder 21 by the force of the electrode 25 trying to return to its original shape. This improves the contact between the electrode 25 and the second protruding portion 21b of the holder 21 in the brush unit 20, thereby enabling a more stable electrical connection between the electrode 25 and the second protruding portion 21b.

[0046] (First Modification) Next, a first modification of the brush unit will be described. As shown in Figures 4 and 5, a brush unit 20A according to the first modification includes a holder 21A and a sleeve 24A having a different configuration, instead of the holder 21 and sleeve 24 according to the above embodiment. A holder oil passage hole 21e is provided in the holder main body 21c of the holder 21A, connecting the outer peripheral surface and the inner peripheral surface of the holder main body 21c. An oil passage is also provided in the housing 4. The oil passage provided in the housing 4 opens into the wall surface of the recess 4a into which the brush unit 20A is fitted. The holder oil passage hole 21e provided in the holder 21A communicates with an oil passage provided in the housing 4.

[0047] An inner oil passage groove 24a is provided on the inner circumferential surface of the sleeve 24A. The inner oil passage groove 24a extends in the direction in which the spring 23 biases the brush 22. In this embodiment, a plurality of inner oil passage grooves 24a are provided on the inner circumferential surface of the sleeve 24A. The sleeve 24A also has an inlet oil passage hole 24b that connects the outer circumferential surface of the sleeve 24A to the inner oil passage groove 24a. The inlet oil passage hole 24b is provided at a position facing the holder oil passage hole 21e in a direction perpendicular to the biasing direction of the brush 22 by the spring 23. The outer circumferential surface of the sleeve 24A also has an oil passage groove 24c that extends in the circumferential direction at a position where the inlet oil passage hole 24b opens. As a result, the inlet oil passage hole 24b can communicate with the holder oil passage hole 21e provided in the holder 21 via the oil passage groove 24c, even if it does not face the holder oil passage hole 21e provided in the holder 21.

[0048] In addition, the extension length of the first protrusion portion 21a from the holder main body portion 21c is set so that oil flowing through the inner oil passage groove 24a can pass between the tip of the first protrusion portion 21a and the outer surface of the brush 22.

[0049] In this case, in the brush unit 20A, the holder oil passage hole 21e, the introduction oil passage hole 24b, and the inner oil passage groove 24a form an oil passage indicated by the arrow Y1 connecting the housing 4 and the rotating shaft 2. At the end of the holder 21A on the first opening H21a side, oil passes through the gap between the outer circumferential surface of the brush 22 and the holder 21A (the tip of the first protruding portion 21a). The oil flow direction may be opposite to the direction indicated by the arrow Y1. The shaft conductive portion 10 only needs to have an oil passage hole formed around the steel ball 12 so that oil can flow from the brush unit 20A side to the inside of the rotating shaft 2. In this way, the brush unit 20A can also be used as an oil passage for flowing oil, such as lubricating oil, between the housing 4 and the rotating shaft 2.

[0050] (Second Modification) Next, a second modification of the brush unit will be described. As shown in FIGS. 6 and 7 , a brush unit 20B according to the second modification includes a holder 21B and a sleeve 24B with different configurations, instead of the holder 21 and the sleeve 24 according to the above embodiment. A first oil passage hole 21f is provided in the first protruding portion 21a of the holder 21B. In this embodiment, a plurality of first oil passage holes 21f are provided in the first protruding portion 21a. A second oil passage hole 21g is provided in the second protruding portion 21b of the holder 21B. In this embodiment, a plurality of second oil passage holes 21g are provided in the second protruding portion 21b. An oil passage is provided in the housing 4. The oil passage provided in the housing 4 opens into the wall surface of the recess 4a into which the brush unit 20B is fitted. The second oil passage hole 21g provided in the holder 21B communicates with an oil passage provided in the housing 4.

[0051] The sleeve 24B has a sleeve oil passage hole 24e formed in a portion between the inner and outer circumferential surfaces thereof, the sleeve oil passage hole 24e extending in the direction in which the brush 22 is urged by the spring 23. In this embodiment, a plurality of the sleeve oil passage holes 24e are formed around a central hole (a hole that accommodates the brush 22, etc.) of the cylindrical sleeve 24. The sleeve oil passage holes 24e penetrate the sleeve 24B in the direction in which the brush 22 is urged by the spring 23. The electrode 25 is sized so as not to block the sleeve oil passage hole 24e formed in the sleeve 24B.

[0052] The second oil passage hole 21g provided in the second overhanging portion 21b of the holder 21B and the sleeve oil passage hole 24e provided in the sleeve 24B are connected to each other. The first oil passage hole 21f provided in the first overhanging portion 21a of the holder 21B and the sleeve oil passage hole 24e provided in the sleeve 24B are connected to each other. The sleeve 24B is accommodated in the accommodation space R so that the second oil passage hole 21g and the sleeve oil passage hole 24e are connected to each other and the first oil passage hole 21f and the sleeve oil passage hole 24e are connected to each other. However, the sleeve 24B may have a groove extending in the circumferential direction on its end face facing the second overhanging portion 21b. The second oil passage hole 21g and the sleeve oil passage hole 24e may be connected to each other via this groove. Similarly, the sleeve 24B may have a groove extending in the circumferential direction on the end face facing the first protruding portion 21 a, and the first oil passage hole 21 f and the sleeve oil passage hole 24 e may be connected to each other via this groove.

[0053] In this case, the brush unit 20B has an oil passage indicated by arrow Y2 that connects the housing 4 and the rotating shaft 2 side, formed by the second oil passage hole 21g, the sleeve oil passage hole 24e, and the first oil passage hole 21f. The oil flow direction may be opposite to the direction indicated by arrow Y2. The shaft conductive part 10 only needs to have oil passage holes formed around the steel balls 12 so that oil can flow from the brush unit 20B side to the inside of the rotating shaft 2. In this way, the brush unit 20B can also be used as an oil passage for flowing oil such as lubricating oil between the housing 4 and the rotating shaft 2.

[0054] (Third Modification) Next, a third modification of the brush unit will be described. As shown in Figures 8 and 9, the brush unit 20C according to the third modification includes a holder 21C and a sleeve 24C with a different configuration, instead of the holder 21 and sleeve 24 according to the above embodiment. A holder oil passage hole 21e is provided in the holder main body 21c of the holder 21C, connecting the outer peripheral surface and the inner peripheral surface of the holder main body 21c. The brush unit 20C according to this modification has the same configuration as the brush unit 20A according to the first modification. Note that an oil passage is provided in the housing 4. The oil passage provided in the housing 4 opens into the wall surface of the recess 4a into which the brush unit 20C is fitted. The holder oil passage hole 21e provided in the holder 21C communicates with the oil passage provided in the housing 4.

[0055] An outer oil passage groove 24f is provided on the outer peripheral surface of the sleeve 24C. The outer oil passage groove 24f extends in the direction in which the spring 23 biases the brush 22. In this embodiment, a plurality of outer oil passage grooves 24f are provided on the outer peripheral surface of the sleeve 24C. The holder oil passage hole 21e faces the outer oil passage groove 24f provided in the sleeve 24C. However, a groove extending in the circumferential direction may be provided on the outer peripheral surface of the sleeve 24C at a position facing the holder oil passage hole 21e of the holder 21C. The holder oil passage hole 21e and the outer oil passage groove 24f may be connected to each other via this groove.

[0056] In this case, in the brush unit 20C, the holder oil passage hole 21e and the outer oil passage groove 24f form an oil passage indicated by arrow Y3 connecting the housing 4 and the rotating shaft 2. A connecting oil passage 24g connecting the outer peripheral surface of the sleeve 24C to the inner peripheral surface of the sleeve 24C may be provided on the end face of the holder 21C on the side of the first opening H21a. The outer oil passage groove 24f may be connected to the gap between the tip of the first protrusion 21a and the outer peripheral surface of the brush 22 via the connecting oil passage 24g. The oil flow direction may be opposite to the direction indicated by arrow Y3. The shaft conductive portion 10 may be provided with an oil passage hole around the steel ball 12 so that oil can flow from the brush unit 20C side to the inside of the rotating shaft 2. In this way, the brush unit 20C can also be used as an oil passage for flowing oil, such as lubricating oil, between the housing 4 and the rotating shaft 2.

[0057] (Fourth Modification) Next, a fourth modification of the brush unit will be described. As shown in FIG. 10 , a brush unit 20D according to the fourth modification includes an electrode 25D with a different configuration instead of the electrode 25 according to the above embodiment. The electrode 25D has an outer diameter larger than the outer diameter of the sleeve 24. The outer edge 25b of the electrode 25D is sandwiched between the holder main body 21c and the second protruding portion 21b at the inside of the corner K where the holder main body 21c and the second protruding portion 21b are connected to each other. In this embodiment, a tapered surface 21h that connects to the corner K is provided on the inner circumferential surface of the holder main body 21c. The outer edge 25b of the electrode 25D is sandwiched between the tapered surface 21h of the holder main body 21c and the second protruding portion 21b.

[0058] For example, as described with reference to FIG. 2B , the electrode 25D may be sandwiched between the second protruding portion 21b and the holder main body 21c at the corner K by bending the end portion 21d of the holder main body 21c. In this case, the electrode 25D may have a cylindrical portion along the inner circumferential surface of the end portion 21d of the holder main body 21c at the outer edge portion of the electrode 25D before the outer edge portion 25b is sandwiched. This cylindrical portion of the electrode 25D may be folded together with the end portion 21d when the end portion 21d of the holder main body 21c is bent to form the second protruding portion 21b. In other words, the outer edge portion of the electrode 25D may have a double-layered structure.

[0059] In this way, in brush unit 20D, outer edge portion 25b of electrode 25D is sandwiched between second protruding portion 21b and holder main body portion 21c, thereby more firmly fixing electrode 25D to holder 21. Therefore, in brush unit 20D, electrode 25D and holder 21 can be electrically connected more stably.

[0060] (Fifth Modification) Next, a fifth modification of the brush unit will be described. As shown in FIG. 11 , the brush unit 20E according to the fifth modification includes a holder 21E having a different configuration, instead of the holder 21 according to the above embodiment. The holder 21E has a first protruding portion 21a, a second protruding portion 21j, and a holder main body 21c. The second protruding portion 21j protrudes inward from the second opening H21b of the holder main body 21c. The second protruding portion 21j protrudes from the second opening H21b and covers the entire second opening H21b. The electrode 25 is sandwiched between the second protruding portion 21j and the sleeve 24.

[0061] In this case, the first protruding portion 21a may be formed by bending the end of the holder main body 21c, similar to the second protruding portion 21b described with reference to FIG. 2B. In this case, the first protruding portion 21a is formed by bending the sleeve 24 so as to press it against the second protruding portion 21j. As a result, the sleeve 24 and the electrode 25 are sandwiched between the first protruding portion 21a and the second protruding portion 21j. Even in this case, the brush unit 20E can ensure a stable conductive path with higher conductivity.

[0062] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments.

[0063] Although a coil spring 23 is used as the biasing portion that biases the brush 22, etc., a biasing portion of another configuration may be used as long as it can bias the brush 22, etc. The shaft conductive portion 10 is not limited to being provided with a steel ball 12. The shaft conductive portion 10 may be configured to be able to abut against the end surface S of the brush 22 (for example, a configuration having a convex portion). Furthermore, the shaft conductive portion 10 is not limited to being provided with a steel ball 12; a steel ball may be attached to the tip of the brush 22, and this steel ball may abut against the bottom surface of the recess in the shaft conductive portion 10.

[0064] Although the connection device 1 electrically connects the rotating shaft 2 and the housing 4, the rotating shaft 2 may be electrically connected to a conductor other than the housing 4. Parts of the configurations of the above-described embodiment and each modified example may be rearranged as appropriate.

[0065] DESCRIPTION OF SYMBOLS 1... Connection device, 2... Rotating shaft, 4... Housing (conductor), 10... Shaft conductive part, 20, 20A to 20E... Brush unit, 21, 21A to 21C, 21E ...Holder, 21a...First overhang, 21b, 21j...Second overhang, 21c...Holder main body, 21e...Holder oil passage hole, 21f...First oil passage hole, 21g ...Second oil passage hole, 22...Brush, 23...Spring (biasing part), 24, 24A to 24C...Sleeve, 24a...Inner oil passage groove, 24b...Introduction oil passage hole, 24f...Outer oil passage groove, 24e...Sleeve oil passage hole, 25...Electrode, 26...Wiring, H21a...First opening, H21b...Second opening, K...Corner, R...Accommodation space.

Claims

1. A brush unit that is attached to a conductor and contacts a shaft conductive part provided on a rotating shaft to electrically connect the conductor and the shaft conductive part, the brush unit comprising: A holder that is attached to the conductor, has conductivity, and has an accommodation space provided inside; A brush that is accommodated in the accommodation space and contacts the shaft conductive part through a first opening provided in the holder, the brush having conductivity; An urging part that urges the brush toward the first opening side; A cylindrical sleeve that is accommodated in the accommodation space, has the brush disposed inside, and holds the brush slidably in the urging direction of the brush by the urging part; An electrode having conductivity; A wiring that connects the brush and the electrode; The holder includes: A holder main body part that is provided so as to surround the sleeve and has a cylindrical shape extending in the urging direction of the brush by the urging part, and has a cylindrical one-end opening as the first opening; A second protruding part that protrudes inward from a second opening on the opposite side of the first opening in the holder main body part; The second protruding part faces an end face on the second opening side of the sleeve in the urging direction of the brush by the urging part; The electrode is sandwiched between the second protruding part and the sleeve.

2. The holder further has a first protruding part that protrudes inward from the first opening in the holder main body part, The first protruding part faces an end face on the first opening side of the sleeve in the urging direction of the brush by the urging part, The sleeve and the electrode are sandwiched between the first protruding part and the second protruding part. The brush unit according to claim 1.

3. A first oil passage hole is provided in the first protruding part, A second oil passage hole is provided in the second protruding part, A sleeve oil passage hole extending in the urging direction of the brush by the urging part is provided in a portion between the inner peripheral surface and the outer peripheral surface of the sleeve. The brush unit according to claim 2.

4. A holder oil passage hole that connects the outer peripheral surface and the inner peripheral surface of the holder main body part is provided in the holder main body part, An outer oil groove extending in the urging direction of the brush by the urging part is provided on the outer peripheral surface of the sleeve. The brush unit according to claim 1.

5. The holder main body portion is provided with a holder oil passage hole that connects the outer peripheral surface and the inner peripheral surface of the holder main body portion. An inner oil passage groove extending in the biasing direction of the brush by the biasing portion is provided on the inner peripheral surface of the sleeve. Further, the sleeve is provided with an introduction oil passage hole that connects the outer peripheral surface of the sleeve and the inner oil passage groove. The brush unit according to claim 1.

6. The electrode is elastically deformable in the sandwiching direction between the second protruding portion and the sleeve, and is sandwiched in a compressed state by the second protruding portion and the sleeve. The brush unit according to claim 1.

7. The outer edge portion of the electrode is sandwiched by the holder main body portion and the second protruding portion at the corner where the holder main body portion and the second protruding portion are connected to each other. The brush unit according to claim 1.

8. A connecting device for electrically connecting a rotating shaft and a conductor, including a shaft conductive portion that is attached to an end of the rotating shaft and has conductivity, and one end of which abuts against the shaft conductive portion, and the other end of which is attached to the conductor, and the brush unit according to any one of claims 1 to 7 that electrically connects the shaft conductive portion and the conductor. A connecting device comprising.

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