Slip ring

Abstract

Provided is a slip ring that is capable of good conduction.　This slip ring 1 comprises: an annular conductive ring 30; a conductive shaft 20 that is inserted into the conductive ring 30 and is positioned so as to be relatively rotatable with regard to the conductive ring 30; a current collector element 4 that is positioned between the conductive ring 30 and the conductive shaft 20; and a bearing 41 that pivotally supports the conductive shaft 20 and includes a lubricant. In the slip ring 1, a lubricant receiving section 22 is positioned between the current collector element 4 and the bearing 41, which is located above the same.

Description

slip ring

[0001] The present invention relates to a slip ring, for example, a slip ring for electrically connecting a rotating element and a stationary element in a rotating mechanism.

[0002] Slip rings are known in various industrial fields for electrically connecting a rotating element and a stationary element in a rotating mechanism. The slip ring electrically connects the conductive ring and the conductive shaft through a current collecting element disposed between the conductive ring and the conductive shaft.

[0003] For example, the slip ring disclosed in Patent Document 1 includes an annular outer electrode, an inner electrode, and a roller current collector. The roller current collector is disposed radially between the outer electrode and the inner electrode and is in contact with both. The roller current collector performs a so-called planetary motion, revolving around its axis while rotating, in response to the rotation of the inner electrode relative to the outer electrode. This allows the inner electrode and the outer electrode to be electrically connected even when the inner electrode rotates relative to the outer electrode.

[0004] WO 2023 / 021923 (pages 5 and 6, Figure 1)

[0005] The slip ring of Patent Document 1 is supported by bearings provided at both axial ends of the inner electrode. However, there is a risk that the lubricant used in the upper bearing may leak and adhere to the roller current collector, the inner electrode, or the outer electrode, resulting in an increase in electrical resistance.

[0006] The present invention has been made in view of these problems, and has as its object to provide a slip ring that allows good current flow.

[0007] In order to solve the above problems, the slip ring of the present invention includes an annular conductive ring, a conductive shaft inserted into the conductive ring and rotatable relative to the conductive ring, a current collecting element disposed between the conductive ring and the conductive shaft, and a bearing containing lubricant that supports the conductive shaft, wherein the slip ring has a lubricant receiving portion disposed between the current collecting element and the bearing located above it. This prevents the lubricant from entering between the conductive ring and the current collecting element or between the conductive shaft and the current collecting element, thereby maintaining good electrical conductivity.

[0008] The receiving portion may be disposed below the fitting portion between the bearing and the conductive shaft or the fitting portion between the bearing and the conductive ring. By disposing the receiving portion below the fitting portion, which is particularly prone to lubricant leakage, it is possible to efficiently prevent the lubricant from entering between the conductive ring and the current collecting element or between the conductive shaft and the current collecting element.

[0009] The receiving portion may be provided on one of the conductive ring and the conductive shaft, whichever is the rotating member, so that the receiving portion can be easily disposed in a position close to the fitting portion between the rotating member and the bearing.

[0010] The receiving portion may be provided on one of the conductive ring and the conductive shaft, whichever is stationary, thereby preventing the lubricant from scattering.

[0011] The receiving portion may be formed with a recess that is open to the bearing side, whereby the lubricant can be collected in the recess.

[0012] The receiving portion may be formed with a guide portion extending toward the bearing, whereby lubricant leaking from the bearing is more easily guided to the guide portion.

[0013] The receiving portion may be non-conductive and may be separate from the conductive ring and the conductive shaft, thereby enabling a stable current flow to be maintained with a simple configuration.

[0014] The slip ring may be a rotary connector in which the current collecting element is a current collector, thereby providing a slip ring with a long life and low electrical resistance.

[0015] FIG. 1 is a cross-sectional view showing a slip ring in embodiment 1 of the present invention. FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1. FIG. 3 is a view for explaining the main parts of the slip ring in embodiment 1. FIG. 4 is a view for explaining the main parts of a receiving part in embodiment 2 of the present invention. FIG. 5 is a view for explaining the main parts of a receiving part in embodiment 3 of the present invention. FIG. 6 is a view for explaining the main parts of a slip ring in embodiment 4 of the present invention. FIG. 7 is a view for explaining the main parts of a slip ring in embodiment 5 of the present invention.

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A slip ring according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0017] A slip ring according to a first embodiment will be described with reference to Figures 1 to 3. In the following description, the top and bottom of the slip ring are defined as the top and bottom when viewed from the front of Figure 1.

[0018] The rotary connector 1 as a slip ring of this embodiment is placed vertically and is used, for example, at a rotating point in a rotating mechanism. The rotary connector 1 passes electricity supplied from an external power source to a rotating shaft in the rotating mechanism.

[0019] 1 and 2, the rotary connector 1 is mainly composed of a rotating element 2, a stationary element 3, seven roller current collectors 4 as current collecting elements, and seven rotary spacers 5. In this embodiment, the roller current collectors 4 and rotary spacers 5 are evenly spaced in the circumferential direction, but the number and arrangement thereof may be changed as appropriate.

[0020] The rotating element 2 includes a conductive shaft 20 , a lower slinger 21 , an upper slinger 22 as a receiving portion, a lower bearing 40 , and an upper bearing 41 .

[0021] The conductive shaft 20 is connected to a rotation shaft (not shown) of the rotation mechanism. The conductive shaft 20 is provided so as to be rotatable relative to the stationary element 3 by being rotated by the rotation shaft.

[0022] The conductive shaft 20 is made of a highly conductive material and has a stepped cylindrical shape. The conductive shaft 20 has a large diameter body portion 23, a lower small diameter body portion 24, and an upper small diameter body portion 25. The conductive shaft 20 may be hollow.

[0023] The outer peripheral surface 23a of the large-diameter body portion 23 is plated with a highly conductive material such as silver. Note that the plating is not shown in the figure because it is thin and would make the drawing too complicated. The same applies to plating in the following description.

[0024] The lower small diameter body portion 24 extends axially downward from the center of the lower end face of the large diameter body portion 23. The lower small diameter body portion 24 has a smaller diameter than the large diameter body portion 23. The lower slinger 21 is fitted onto the lower small diameter body portion 24.

[0025] The lower slinger 21 is formed in an annular shape from a non-conductive material. The lower slinger 21 has a cylindrical rim portion 21a extending in the axial direction and a flange portion 21b that projects radially outward from the upper end of the rim portion 21a. A lower small-diameter body portion 24 of the lower slinger 21 is press-fitted and fixed to the rim portion 21a. The lower slinger 21 also abuts against the large-diameter body portion 23 in the axial direction.

[0026] The upper small diameter body portion 25 is cylindrical and extends axially upward from the center of the upper end face of the large diameter body portion 23. The upper small diameter body portion 25 has a smaller diameter than the large diameter body portion 23. The upper slinger 22 is fitted onto the upper small diameter body portion 25.

[0027] The upper slinger 22 is formed in an annular shape from a non-conductive material, such as a polymer. The upper slinger 22 has a cylindrical inner rim portion 22a extending in the axial direction, a circular disk-shaped bottom portion 22b that projects radially outward from the lower end of the inner rim portion 22a, and an outer rim portion 22c that extends axially upward from the outer radial end of the bottom portion 22b. The inner rim portion 22a, bottom portion 22b, and outer rim portion 22c define an annular groove 22d as a recess that is open axially upward.

[0028] The upper small diameter body portion 25 is press-fitted and fixed in a liquid-tight manner to the inner rim portion 22a of the upper slinger 22. The upper slinger 22 also abuts against the large diameter body portion 23 in the axial direction.

[0029] The stationary element 3 can be connected to an external power source (not shown) and is mainly composed of a conductive ring 30, a lower guide plate 31, an upper guide plate 32, a housing 35, and a cover 36.

[0030] The conductive ring 30 is cylindrical and made of a highly conductive material. The inner peripheral surface 30a of the conductive ring 30 is plated with a highly conductive material such as silver. Inside the conductive ring 30, the large-diameter body portion 23 of the conductive shaft 20 of the rotating element 2, the roller current collectors 4, and the rotation spacers 5 are arranged.

[0031] The lower guide plate 31 is formed in a cylindrical shape and is disposed below the conductive ring 30 .

[0032] A lower recess 31 a and an upper recess 31 b are formed in the radial center of the lower guide plate 31. The lower recess 31 a and the upper recess 31 b are separated in the axial direction by an annular flange 31 c that protrudes inward.

[0033] Specifically, the lower recess 31a is recessed axially upward from the lower end face of the lower guide plate 31 and is open axially downward and toward the inner diameter side. The upper recess 31b is recessed axially downward from the upper end face of the lower guide plate 31 and is open axially upward and toward the inner diameter side. The flange 31c protrudes toward the inner diameter side from the upper end of the inner circumferential surface of the lower recess 31a.

[0034] A lower bearing 40 is inserted into the lower recess 31a. The lower bearing 40 abuts against the flange 31c in the axial direction.

[0035] The lower bearing 40 and the upper bearing 41 are formed in an annular shape from an insulating and porous resin material. The lower bearing 40 and the upper bearing 41 are impregnated with oil as a lubricant. The lower bearing and the upper bearing may be bearings, roller bearings, or the like, and the type of bearing may be changed as appropriate as long as it contains a lubricant.

[0036] The lower small diameter body portion 24 of the conductive shaft 20 of the rotating element 2 is inserted into the lower guide plate 31. The lower small diameter body portion 24 passes through the through hole of the flange 31c from the upper recess 31b side and is fitted into the lower bearing 40.

[0037] The lower slinger 21, which is fixed to the lower small-diameter body portion 24, is disposed on the inner diameter side of the lower guide plate 31. The rim portion 21a of the lower slinger 21 penetrates the flange 31c from the upper recess 31b side and abuts against the lower bearing 40. The flange portion 21b of the lower slinger 21 protrudes outward beyond the through-hole in the flange 31c.

[0038] The lower slinger 21 rotates integrally with the conductive shaft 20. The lower bearing 40 rotates integrally with the lower small diameter body portion 24 and is slidable relative to the lower guide plate 31.

[0039] The lower end of the rotating spacer 5 is disposed in contact with the upper recess 31b on the outer diameter side of the flange portion 21b of the lower slinger 21, allowing the rotating spacer 5 to roll. The outer peripheral side surface of the upper recess 31b is disposed on the inner diameter side of the inner peripheral surface 30a of the conductive ring 30, allowing the rotating spacer 5 to roll without contacting the conductive ring 30.

[0040] The upper guide plate 32 is formed in a cylindrical shape and is disposed above the conductive ring 30. The upper guide plate 32 has a through hole 32a that passes through the center in the radial direction in the axial direction. The lower end of the through hole 32a forms a recess 32b that expands in diameter toward the outer diameter side.

[0041] An upper bearing 41 is inserted into the through hole 32a.

[0042] The upper small diameter body portion 25 of the conductive shaft 20 of the rotating element 2 is inserted into the upper guide plate 32. The upper small diameter body portion 25 is fitted into the upper bearing 41 through the through hole 32a from the recess 32b side.

[0043] Additionally, the upper slinger 22 fixed to the upper small-diameter body portion 25 is disposed within the through-hole 32a. The inner rim portion 22a of the upper slinger 22 abuts against the upper bearing 41 in the axial direction. In other words, the lower slinger 21 and the upper slinger 22 function as a spacer, maintaining the axial position of the conductive shaft 20.

[0044] The upper slinger 22 rotates integrally with the conductive shaft 20. The upper bearing 41 rotates integrally with the upper small diameter body portion 25 and is slidable relative to the upper guide plate 32.

[0045] Furthermore, the outer rim portion 22c of the upper slinger 22 is shorter than the inner rim portion 22a, and the outer rim portion 22c is spaced axially downward from the upper bearing 41. Note that the outer rim portion 22c may abut against the upper bearing 41 in the axial direction.

[0046] The upper end of the rotation spacer 5 is placed in contact with the recess 32b, allowing the rotation spacer 5 to roll. The outer circumferential surface of the recess 32b has approximately the same diameter as the outer circumferential surface of the upper recess 31b of the lower guide plate 31, allowing the rotation spacer 5 to be guided in its rolling motion.

[0047] The housing 35 has a cross section in the shape of an upside-down U. The cover 36 is formed in the shape of a thin plate.

[0048] The conductive ring 30, the lower guide plate 31, and the upper guide plate 32 are fitted inside the housing 35. A cover 36 is fixed to the lower end of the cylindrical portion of the housing 35 by bolts.

[0049] The roller current collector 4 is made of a highly conductive metal, such as copper or a copper alloy, and is formed into an elastically deformable cylindrical shape. The outer circumferential surface of the roller current collector 4 is plated with a highly conductive material, such as silver.

[0050] The roller current collector 4 is disposed axially between the lower guide plate 31 and the upper guide plate 32. The roller current collector 4 is disposed radially compressed between the large diameter body portion 23 of the conductive shaft 20 and the conductive ring 30. This allows the roller current collector 4 to be maintained in contact with the conductive shaft 20 and the conductive ring 30.

[0051] The roller current collector 4 is in contact with the large diameter body 23 and the conductive ring 30 in a dry state, i.e., without any lubricant present, thereby stably maintaining the electrical resistance between the conductive shaft 20 and the roller current collector 4 and the electrical resistance between the roller current collector 4 and the conductive ring 30.

[0052] The rotating spacer 5 is made of an insulating resin material and has a cylindrical shape. The rotating spacer 5 is longer in the axial direction than the roller current collector 4 and has a smaller diameter than the roller current collector 4.

[0053] As shown in Fig. 2, the central axis A1 of the rotating spacer 5 is located radially outward of the central axis A2 of the roller current collector 4 and is disposed circumferentially between adjacent roller current collectors 4. Note that in Fig. 2, the lower slinger 21 is not shown in order to clearly show that the rotating spacer 5 is located within the upper recess 31b of the lower guide plate 31.

[0054] When the rotation shaft of the rotation mechanism rotates, the conductive shaft 20 also rotates accordingly. In response to the rotation of the conductive shaft 20, each roller current collector 4 rotates in the opposite direction to the rotation direction of the conductive shaft 20 while revolving in the rotation direction of the conductive shaft 20 (see the thick black arrow).

[0055] Each rotation spacer 5 rotates in the opposite direction to the rotation of the roller current collector 4 as the roller current collector 4 rotates around its axis, while revolving in the same direction as the revolution of the roller current collector 4 (see the bold arrow).

[0056] The roller current collectors 4 adjacent in the circumferential direction are prevented from contacting each other by the rotation spacers 5 disposed between them in the circumferential direction. In other words, the rotation spacers 5 maintain the circumferential distance between the adjacent roller current collectors 4.

[0057] As described above, in the rotary connector 1 of this embodiment, the upper slinger 22 is disposed between the roller current collector 4 and the upper bearing 41 located vertically above it. Oil leaking from the upper bearing 41 drips onto this upper slinger 22, preventing lubricant from entering between the conductive ring 30 and the roller current collector 4 or between the conductive shaft 20 and the roller current collector 4.

[0058] In other words, the rotary connector 1 is kept dry by the upper slinger 22. This allows good electrical conductivity to be maintained in the rotary connector 1. Note that the vertical direction in the present invention only needs to include at least a vertical component, and for example, the slip ring may be tilted relative to the vertical direction.

[0059] Furthermore, the rotary connector 1 is kept dry by the lower slinger 21, which prevents oil leaking from the lower bearing 40 from scattering toward the roller current collector 4.

[0060] Additionally, the upper small diameter body portion 25 of the conductive shaft 20 is fitted into the upper bearing 41. This fitting location includes the boundary between the conductive shaft 20 and the upper bearing 41, so oil that has entered between the upper small diameter body portion 25 and the upper bearing 41 may drip along the upper small diameter body portion 25. In other words, oil is prone to leaking from the fitting location.

[0061] Since the upper slinger 22 is positioned below this mating point, it is possible to efficiently prevent lubricant from entering between the conductive ring 30 and the roller current collector 4, or between the conductive shaft 20 and the roller current collector 4.

[0062] Additionally, the upper slinger 22 is fitted and fixed to the outside of the conductive shaft 20 below the fitting location of the upper small diameter body portion 25 that is fitted with the upper bearing 41. With such a simple configuration, the upper slinger 22 can be positioned close to the fitting location.

[0063] Furthermore, a groove 22d is formed in the upper slinger 22. The groove 22d can collect oil.

[0064] Furthermore, the inner rim portion 22a of the upper slinger 22 abuts against the upper bearing 41. Oil that enters between the inner rim portion 22a and the upper bearing 41 is likely to drip along the upper slinger 22. Furthermore, at the point where the inner rim portion 22a abuts against the upper bearing 41, a resistance force from the inner rim portion 22a acts on the upper bearing 41, making it easy for oil to seep out from that point. This also makes it easy for the inner rim portion 22a to guide the oil. The inner rim portion 22a of the upper slinger 22 is a guide portion that guides oil that leaks from the upper bearing 41.

[0065] This makes it possible to efficiently prevent the lubricant from entering between the conductive ring 30 and the roller current collector 4 and between the conductive shaft 20 and the roller current collector 4 .

[0066] Furthermore, the inner rim portion 22a constitutes a part of the groove 22d in the upper slinger 22. This allows the oil guided to the inner rim portion 22a to be efficiently collected in the groove 22d.

[0067] Furthermore, the outer rim portion 22c of the upper slinger 22 is spaced axially downward from the upper bearing 41. This not only makes it easier for oil leaking from the upper bearing 41 to be guided to the inner rim portion 22a on the inner diameter side, but also makes it more difficult for oil to be guided downward from the outer periphery of the outer rim portion 22c.

[0068] Furthermore, the gap between the inner rim portion 22a of the upper slinger 22 and the upper small diameter body portion 25 of the conductive shaft 20 is sealed, thereby preventing oil from passing through the gap between the inner rim portion 22a and the upper small diameter body portion 25.

[0069] In addition, the gap between the inner rim portion 22a of the upper slinger 22 and the upper small diameter body portion 25 of the conductive shaft 20 is sealed by press-fitting the upper small diameter body portion 25 into the inner rim portion 22a. In other words, the O-ring 326 and the annular groove 325a for arranging the O-ring 326, as in Example 4 (see FIG. 6 ) described below, are omitted.

[0070] As a result, the rotary connector 1 of this embodiment can prevent the high-frequency current from being interrupted by the O-ring 326, compared to Example 4 described below. Furthermore, the rotary connector 1 can prevent the high-frequency current from being dispersed by undulations caused by the annular groove 325a provided at the current-carrying point. With such a simple configuration, the rotary connector 1 can maintain a stable current flow.

[0071] Furthermore, the upper slinger 22 is non-conductive and separate from the conductive shaft 20. This prevents conductive undulations from being formed in the current-carrying portions of the conductive shaft 20. With such a simple configuration, the rotary connector 1 can maintain a stable current flow.

[0072] Although the upper slinger is exemplified as being non-conductive, it may also be made of a conductive material such as an aluminum alloy, and in such a configuration, it is preferable that there is insulation between the upper slinger and the conductive shaft.

[0073] The slip ring of this embodiment is a rotary connector 1 having a plurality of roller current collectors 4. Therefore, compared to slip rings having current collecting elements such as brushes and cantilevers, it is possible to provide a slip ring having a long life and low electrical resistance.

[0074] Furthermore, since the lower bearing 40 and the upper bearing 41 of the rotary connector 1 are insulating, a stable current flow can be maintained.

[0075] Next, a rotary connector according to a second embodiment will be described with reference to Fig. 4. Note that the description of the same configuration as in the first embodiment will be omitted.

[0076] 4, in the upper slinger 122 of this embodiment, the outer diameter side of the groove 122d is further recessed toward the outer diameter side and the axial center. More specifically, a curved surface 122e is formed that continues from the outer diameter end of the upper surface of the bottom portion 122b to the upper end of the outer rim portion 122c. The curved surface 122e protrudes toward the outer diameter side and the axial center.

[0077] With this configuration, the volume of the groove 122d is larger than that of the groove 22d of the first embodiment, so that oil is less likely to scatter from the groove 122d.

[0078] The inner peripheral surface of the outer rim portion 122c is part of the curved surface 122e, and is curved inward in the axial direction, thereby preventing oil from scattering from the groove 122d.

[0079] Next, a rotary connector according to a third embodiment will be described with reference to Fig. 5. Note that the description of the same configuration as in the first embodiment will be omitted.

[0080] 5, a felt sheet 226 is attached to the groove 22d of the upper slinger 22 of this embodiment. This allows oil to be absorbed by the felt sheet 226, making it less likely to scatter from the groove 22d.

[0081] It should be noted that, as long as it is capable of absorbing oil, an absorbent member other than the felt sheet 226, such as a fabric sheet, may be disposed, and may be changed as appropriate.

[0082] Next, a rotary connector according to a fourth embodiment will be described with reference to Fig. 6. Note that the description of the same configuration as in the first embodiment will be omitted.

[0083] 6, in this embodiment, the gap between the upper slinger 22 and the cylindrical portion 325 of the conductive shaft 320 is sealed by an O-ring 326. The O-ring 326 is recessed radially inward from the outer circumferential surface of the cylindrical portion 325 and is disposed in an annular groove 325a that is open radially outward.

[0084] With this configuration, oil leaking from the upper bearing 41 can be reliably prevented from passing through the gap between the upper slinger 22 and the cylindrical portion 325.

[0085] The groove for locating the O-ring may be formed in the upper slinger. With this configuration, the rotary connector can maintain a stable current flow.

[0086] Next, a rotary connector according to a fifth embodiment will be described with reference to Fig. 7. Note that the description of the same configuration as in the first embodiment will be omitted.

[0087] 7, in the rotary connector 401 of this embodiment, an upper slinger 422 is provided axially between the conductive ring 430 and the upper guide plate 432 in the stationary element 403. In addition, in the rotating element 402, the upper slinger 22 is omitted.

[0088] The upper slinger 422 is fitted into a recess 432b in the upper guide plate 432. The upper slinger 422 has an outer rim portion 422a sandwiched between the conductive ring 430 and the upper guide plate 432 in the axial direction.

[0089] The upper slinger 422 has a bottom portion 422b extending radially inward from the lower end of the outer rim portion 422a, and an inner rim portion 422c extending axially outward from the inner end of the bottom portion 422b. The inner rim portion 422c is disposed near the upper small diameter body portion 25 of the conductive shaft 20 and spaced radially outward from the upper small diameter body portion 25.

[0090] The lower end of the outer rim portion 422a protrudes axially downward beyond the bottom portion 422b. That is, the lower end of the outer rim portion 422a and the bottom portion 422b form a recess 422f that is recessed upward and open downward. The upper end of the rotation spacer 5 abuts against the recess 422f, allowing the rotation spacer 5 to roll.

[0091] Even with this configuration, oil leaking from the upper bearing 41 drips onto the upper slinger 422, preventing lubricant from entering between the conductive ring 30 and the roller collector 4, or between the conductive shaft 20 and the roller collector 4.

[0092] In addition, the upper slinger 422 is provided on the stationary element 403, which makes it difficult for the collected oil to scatter.

[0093] The conductive ring 430 and the upper slinger 422 may be part of the rotating element. With this configuration, the oil is less likely to scatter from the upper slinger 422 due to the centrifugal effect.

[0094] In addition, the upper bearing 41 may be configured to be fixed to the upper guide plate 432 so as not to be rotatable relative to the upper bearing 41, and to slide relative to the conductive shaft 20. With such a configuration, the upper slinger 422 can be easily disposed near the fitting position between the upper bearing 41 and the upper guide plate 432.

[0095] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes modifications and additions that do not deviate from the gist of the present invention.

[0096] For example, in the first to fifth embodiments, the slip ring has been described as a rotary connector using roller collectors as current collecting elements, but the present invention is not limited to this and may be other types of slip rings using brushes, cantilevers, etc. as current collecting elements, and may be modified as appropriate. In addition, if the current collecting elements are brushes, cantilevers, etc., the current collecting elements may be disposed, for example, axially between the outward flange of the conductive shaft and the inward flange of the conductive ring.

[0097] Furthermore, in the above-described Examples 1 to 5, a configuration was described in which the conductive shaft is the rotating element and the conductive ring is the stationary element, but this is not limited to this, and the conductive shaft may be the stationary element and the conductive ring may be the rotating element.

[0098] In addition, in the above-described Examples 1 to 5, the bearing is described as a rotating element, but this is not limited thereto and the bearing may be a stationary element. In such a configuration, it is preferable that the stationary element is provided with a receiving portion, since the receiving portion can be positioned near the fitting portion.

[0099] Furthermore, in Examples 1 to 4, a receiving portion is provided on the rotating element, and in Example 5, a configuration in which a receiving portion is provided on the stationary element is described, but this is not limited to this, and a receiving portion may be provided on each of the rotating element and the stationary element.

[0100] In addition, in the first to fifth embodiments, the receiving portion is described as being separate from the conductive shaft or the conductive ring, but this is not limiting and the receiving portion may be formed on the conductive shaft or the conductive ring.

[0101] Furthermore, in Examples 1 to 5, it has been described that the receiving portion has a recessed annular groove formed therein, but this is not limited to this, and as long as it is recessed at least axially downward, it may be a recessed or ended groove, and may be modified as appropriate.

[0102] In addition, in the above-described Examples 1 to 5, it has been described that the recessed portion is an annular groove formed in the receiving portion, but this is not limited thereto, and the recessed portion may be formed by the receiving portion and the conductive shaft.

[0103] Furthermore, the receiving portion may be a flat plate with no recesses formed therein, or may be configured such that only an adsorption member such as the felt sheet in Example 3 is attached to the conductive shaft or the conductive ring. In other words, the shape and configuration of the receiving portion may be changed as appropriate as long as it is possible to prevent the lubricant from entering between the conductive ring and the current collecting element, or between the conductive shaft and the current collecting element.

[0104] Furthermore, in the above-described Examples 1 to 5, oil is used as an example of the lubricant, but the present invention is not limited to this and may be replaced with grease or any other suitable material that can be used as a lubricant.

[0105] DESCRIPTION OF SYMBOLS 1 Rotary connector (slip ring) 2 Rotating element 3 Stationary element 4 Roller current collector (current collecting element) 5 Rotating spacer 20 Conductive shaft 21 Lower slinger 22 Upper slinger (receiving portion) 22d Groove (recess) 30 Conductive ring 41 Upper bearing (bearing) 122 Upper slinger (receiving portion) 122d Groove 320 Conductive shaft 401 Rotary connector (slip ring) 402 Rotating element 403 Stationary element 422 Receiving member (receiving portion) 430 Conductive ring

Claims

1. A slip ring comprising an annular conductive ring, a conductive shaft inserted into the conductive ring and arranged so as to be rotatable relative to the conductive ring, a current collecting element arranged between the conductive ring and the conductive shaft, and a bearing containing a lubricant that supports the conductive shaft, wherein a lubricant receiving portion is arranged between the current collecting element and the bearing located above it.

2. A slip ring according to claim 1, wherein the receiving portion is disposed below the mating portion between the bearing and the conductive shaft or the mating portion between the bearing and the conductive ring.

3. A slip ring according to claim 2, wherein the receiving portion is provided on the rotating member of the conductive ring or the conductive shaft.

4. A slip ring according to claim 1, wherein the receiving portion is provided on the stationary member of the conductive ring or the conductive shaft.

5. A slip ring according to claim 1, wherein the receiving portion is formed with a recess that is open to the bearing side.

6. A slip ring according to claim 1, wherein the receiving portion is formed with a guide portion extending toward the bearing.

7. The slip ring according to claim 1, wherein the receiving portion is non-conductive and is separate from the conductive ring and the conductive shaft.

8. A slip ring according to any one of claims 1 to 7, wherein the slip ring is a rotary connector in which the current collecting elements are current collectors.

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