Energization unit and bearing unit

Abstract

An energization unit (1) comprises: a conductive annular case body (3) in which an opening is formed facing inward in the radial direction; a conductive energization member (4) which is provided inside the case body (3) and protrudes inward in the radial direction from the opening of the case body (3); an elastic member (5) which biases the energization member (4) inward in the radial direction; and a fall prevention portion (6) which prevents the energization member (4) from falling out of the case body (3). A bearing unit (A) comprises: the energization unit (1); and a bearing (2) which includes an outer ring (7), an inner ring (8) disposed on the inner diameter side of the outer ring (7), and rolling elements (9) provided between the outer ring (7) and the inner ring (8).

Description

Power Supply Unit and Bearing Unit

[0001] The present invention relates to a power supply unit provided in a bearing that supports a rotating shaft body such as a motor shaft, and a bearing unit employing this power supply unit.

[0002] As a bearing that supports a rotating shaft body such as a motor shaft of an automotive e-axle, a rolling bearing, particularly a ball bearing, is generally used. In recent years, inverter control has been generally adopted in order to efficiently operate a motor. In particular, in the case of an in-vehicle motor, miniaturization has been achieved from the viewpoint of mounting on a vehicle, and in order to more efficiently use the miniaturized motor, finer control is being performed.

[0003] It has been found that shaft current and shaft voltage occur in this rotating shaft body. When this current passes through the inside of the bearing, electrical erosion may occur on the raceway ring and rolling elements made of metal. Therefore, for example, in Patent Document 1 below, a sliding brush assembly 25 is provided near a countershaft 3c to which the rotation of a motor shaft 1b is transmitted, and a brush contact 5a protruding from a brush holder 5c of the sliding brush assembly 25 is brought into contact with a shaft end portion 3c' of the countershaft 3c to release electricity to a housing 3a, so that the current does not pass through a ball bearing 13 (see FIG. 2 of Patent Document 1, etc.). Further, in Patent Document 2 below, a conductive discharge body 8 is brought into contact with a shaft 68, and the voltage generated in the shaft 68 is released to a grounded housing 69 to suppress discharge in the bearing (see FIG. 24 of Patent Document 2, etc.). Further, in Patent Document 3 below, a conductive filament 30 is brought into contact with a shaft 16 of a motor 12, and the voltage generated in the shaft 16 is released to reduce the shaft current (see FIG. 2 of Patent Document 3, etc.).

[0004] Japanese Patent Application Laid-Open No. 2012-110149, International Publication No. 2019-509007, U.S. Patent No. 8199453

[0005] In the configurations described in Patent Documents 1 to 3, the current is maintained by bringing a brush contact 5a (current-carrying member) into contact with the motor shaft 1b (rotating shaft). However, due to the generation of an oil film, shaft eccentricity, vibration, etc., when the motor shaft 1b rotates at high speed, the tracking ability and posture between the brush contact 5a and the motor shaft become unstable, making it impossible to maintain a stable current and potentially preventing the voltage generated on the motor shaft 1b from being smoothly discharged.

[0006] Therefore, the object of the present invention is to provide an energizing unit that can stably maintain an electrolytic corrosion prevention effect over a long period of time and can be easily assembled, and a bearing unit to which the energizing unit is applied.

[0007] To solve the above problems, the present invention provides a conductive unit comprising: a conductive annular case body having an opening formed radially inward; a conductive current-carrying member provided within the case body and protruding radially inward from the opening of the case body; an elastic member that biases the current-carrying member radially inward; and a fall prevention part that prevents the current-carrying member from falling out of the case body (first configuration).

[0008] In this way, a new bypass path for current is formed between the housing into which the case body is fitted and the rotating shaft body, such as the motor shaft, which is positioned at the annular center of the case body, thereby suppressing electrolytic corrosion of the bearing components. Moreover, by providing a fall prevention part to prevent the current-carrying member from falling off, the current-carrying member will not fall off to the inner diameter side due to vibration or shock during or after the assembly of the current-carrying unit, and the current-carrying unit can be assembled easily.

[0009] In the first configuration, the case body has an annular outer ring portion and a retainer having a claw portion that fits into the outer ring portion from the axial direction and extends in the axial direction, and the fall prevention portion is a projection portion that extends from the conductive member in at least one of its circumferential or axial directions, and the fall prevention portion can be configured such that the fall prevention portion of the conductive member is prevented when the conductive member is displaced radially inward by the projection portion coming into contact with the claw portion. In this way, the fall prevention portion of the conductive member can be effectively suppressed by the contact between the projection portion and the claw portion.

[0010] Furthermore, in the first configuration, the case body has an annular outer ring portion and a retainer having a claw portion that fits axially onto the outer ring portion and extends axially, and a holding member is fixed to the radially outer side of the conductive member, and the fall prevention portion is a projection portion that extends from the holding member so as to project outward from the conductive member in at least one of its circumferential or axial directions, and the fall prevention portion is configured such that when the conductive member is displaced radially inward, the projection portion abuts against the claw portion, thereby preventing the conductive member from falling out (third configuration). In this way, the fall prevention portion of the conductive member can be effectively suppressed by the abutment between the projection portion and the claw portion. Moreover, since the shape of the conductive member, which is relatively difficult to process, can be simplified, there is a possibility that processing costs can be reduced.

[0011] In the first to third configurations, the conductive member can be made of a conductive material composed of metal, carbon, or a conductive resin, rubber, ceramics, or a composite material thereof (fourth configuration). In this way, the conductivity of the conductive unit can be ensured with a simple configuration.

[0012] In the first to fourth configurations, a configuration (fifth configuration) can be adopted in which multiple conductive members are provided along the circumferential direction of the case body. In this configuration, even if the rotating shaft body becomes eccentric in one direction due to vibrations associated with its rotation, and one conductive member fails to follow the eccentricity, resulting in poor contact, the conductive state is maintained by the other conductive members arranged in the same direction. Moreover, even if the conductive state of one conductive member is impaired due to damage or other reasons, the conductive state can be covered by the other conductive members, thus ensuring stable conductive performance.

[0013] In the first to fifth configurations, the elastic member can be an annular member provided across the outer diameter ends of a plurality of current-carrying members, or a metal elastic spring interposed between the outer diameter ends of the current-carrying members and the case body to individually bias the current-carrying members radially inward (sixth configuration). By providing an annular member across the outer diameter ends of a plurality of current-carrying members in this way, a plurality of current-carrying members can be biased toward the inner diameter with a simple configuration. Furthermore, by employing a metal elastic spring as the elastic member to individually bias the current-carrying members radially inward, multiple current-carrying routes can be secured, including a current-carrying route in which current flows directly from the current-carrying member to the case body, and a current-carrying route in which current flows from the current-carrying member to the case body via the elastic member, thereby enabling more stable current-carrying performance.

[0014] The energizing unit relating to all of the above configurations can be used in a bearing unit having an energizing unit, an outer ring, an inner ring disposed on the inner diameter side of the outer ring, and rolling elements provided between the outer ring and the inner ring.

[0015] According to the current-carrying unit of the present invention and the bearing unit employing this current-carrying unit, a bypass path for current is newly formed between the housing into which the case body is fitted and the rotating shaft body, such as the motor shaft, which is positioned at the annular center of the case body. This suppresses electrolytic corrosion of the bearing components. Furthermore, because a fall-prevention part is provided, the current-carrying member will not fall out to the inner diameter side due to vibration or shock during or after the assembly of the current-carrying unit, allowing for easy assembly of the current-carrying unit.

[0016] Cross-sectional view of a bearing unit employing the energizing unit according to the first embodiment of the present invention Cross-sectional view of the main part of Figure 2 along the line II-II in Figure 1 Cross-sectional view of the main part of Figure 2 Cross-sectional view of the main part of Figure 3 along the line IV-IV in Figure 3 Cross-sectional view of the main part of Figure 3 along the line V-V in Figure 3 Cross-sectional view showing a modified example of Figure 3 Cross-sectional view showing a modified example of Figure 2 Cross-sectional view of the main part of the energizing unit according to the second embodiment of the present invention Cross-sectional view of the energizing unit shown in Figure 9 along the line X-X in Figure 9 Exploded perspective view of the energizing unit shown in Figure 9 Cross-sectional view of the main part of the energizing unit according to the third embodiment of the present invention Cross-sectional view of the energizing unit shown in Figure 12 along the line XIII-XIII in Figure 12 Exploded perspective view of the energizing unit shown in Figure 12 Cross-sectional view of the main part of the energizing unit according to the third embodiment of the present invention Cross-sectional view of the main part of the energizing unit according to the fourth embodiment of the present invention Cross-sectional view showing a modified example of Figure 16 along the line XVI-XVI in Figure 15 Cross-sectional view of the main part of the energizing unit according to the fourth embodiment of the present invention Cross-sectional view showing a modified example of the bearing unit shown in Figure 1

[0017] Figure 1 shows a bearing unit A employing the energizing unit 1 according to the first embodiment of the present invention. The bearing unit A consists of the energizing unit 1 and a bearing 2 (a ball bearing in this embodiment). As shown in Figures 1 to 5, the energizing unit 1 has a case body 3, an energizing member 4, an elastic member 5, and a fall prevention part 6. The bearing 2 has an outer ring 7, an inner ring 8 arranged on the inner diameter side of the outer ring 7, rolling elements 9 provided between the outer ring 7 and the inner ring 8, and a cage 10 that holds the rolling elements 9 at predetermined intervals in the circumferential direction.

[0018] The energizing unit 1 is positioned between the rotating shaft 11, such as a motor shaft like an e-axle, and the housing 12, and is located adjacent to the bearing 2 that supports the rotating shaft 11. The housing 12 is electrically grounded. In the following, the direction along the rotating shaft 11 will be referred to as the axial direction, the direction perpendicular to the rotating shaft 11 will be referred to as the radial direction, and the direction along the circumference that makes one full turn around the rotating shaft 11 will be referred to as the circumferential direction.

[0019] The case body portion 3 is a conductive member with an opening formed radially inward. The case body portion 3 is composed of an outer ring portion 13 and a retainer 14.

[0020] The outer ring portion 13 has a cylindrical outer ring portion 15 having a surface normal facing radially, and a flange portion 16 extending radially inward from one axial end of the outer ring portion 15, with a hole in the center and a surface normal facing axially. The retainer 14 has a cylindrical outer ring portion 17 having a surface normal facing radially, and a flange portion 18 extending radially inward from the other axial end of the outer ring portion 17, with a surface normal facing axially. The axial gap between the two flange portions 16 and 18 constitutes the opening of the case body portion 3. Four claw portions 19 extending toward one axial end are provided in a series at four circumferential locations on the inner edge of the flange portion 18 (see Figure 2).

[0021] The outer ring portion 13 is manufactured by press-forming a steel plate, and the retainer 14 is manufactured by injection molding of resin. The outer ring portion 13 and the retainer 14 are integrated by fitting the outer ring portion 17 formed on the retainer 14 into the inner side of the outer ring portion 15 formed on the outer ring portion 13 from the axial direction. The retainer 14 can also be manufactured by press-forming a steel plate in the same way as the outer ring portion 13.

[0022] The conductive member 4 is provided inside the case body 3 and is a conductive member that protrudes radially inward from the opening of the case body 3. In this embodiment, the circumferential end faces of the conductive member 4 are parallel to each other, but it can also be shaped to spread out in a fan shape from the center of the rotating shaft 11. A projection 6a, which serves as a fall prevention part 6, is integrally provided on both sides of the circumferential end of the conductive member 4 on the outer diameter side. The inner diameter surface of the projection 6a is curved to follow the outer edge of the claw part 19. The conductive member 4 is provided so as to be radially movable between circumferentially adjacent claw parts 19 connected to the flange part 18 of the retainer 14.

[0023] In this embodiment, a composite material of metal and carbon is used as the material for the conductive member 4, but as another example, carbon-added polytetrafluoroethylene (PTFE) may be used. The inner diameter surface of the conductive member 4 is composed of a part of the cylindrical surface and is in surface contact with the outer circumferential surface of the rotating shaft 11. An outer circumferential groove 20 is formed on the outer edge of the conductive member 4. The number of conductive members 4 can be determined as appropriate, but it is preferable to use multiple members as in this embodiment.

[0024] As the material for the conductive member 4, in addition to PTFE with added carbon, various conductive materials can be used, such as resins, rubbers, ceramics, or composites thereof that have been imparted with conductivity, such as metal, carbon, or polyetheretherketone (PEEK) with added carbon. Furthermore, the surface of the conductive member 4 (especially the inner diameter surface that slides against the rotating shaft 11) can be treated with a coating to improve conductivity and wear resistance (for example, a conductive diamond-like carbon (DLC) film, a metal film (plating layer, etc.)). Note that in this application, conductivity refers to a volume resistivity of 10 ５ This refers to physical properties of Ωcm or less. Volume resistivity can be measured, for example, by the method specified in JIS K7194.

[0025] The elastic member 5 is a member for biasing the conductive member 4 radially inward. This elastic member 5 is stretched across the outer circumferential groove 20 formed in each conductive member 4 (see Figure 2). In this embodiment, a garter spring made by processing a coiled steel wire into a ring shape is used as the elastic member 5, but for example, a circlip (C-type retaining ring) with a slit in part of the ring or an annular piece of rubber can also be used.

[0026] In the current-carrying unit 1 according to the first embodiment, when the width of the current-carrying member 4 in the axial view is W1 and the amount of protrusion of the protrusion 6a from the circumferential end of the current-carrying member 4 is a (see Figure 3), the ratio a / W1 is designed to be within the range of 1 / 5 to 1 / 4. If the ratio a / W1 is less than 1 / 5, the grip of the protrusion 6a on the claw portion 19 will be insufficient, and if it is greater than 1 / 4, the difficulty of processing the current-carrying member 4 will increase, so it is preferable to keep it within the above range. Also, when the radial width of the protrusion 6a is b and the radius of the elastic member 5 is r (see Figure 5), it is preferable that the relationship b ≥ r holds. By doing so, sufficient strength of the protrusion 6a against the elastic force of the elastic member 5 can be ensured.

[0027] This power supply unit 1 takes into account recommended dimensions to ensure compatibility with conventional power supply units (for example, recommended outer diameter during assembly: φ53.3 mm, recommended width: 4.4 mm, inner diameter when mounting the rotating shaft 11 (a typical e-Axle motor shaft): φ35 mm), and for example, the axial width W1 of the power supply member 4 can be set to 15.7 mm, the height to 4.5 mm, and the axial width W2 of the power supply member 4 to 2.5 mm. In this case, considering the range of the ratio a / W1 and the relationship between b≧r, the recommended dimensions of the protruding portion 6a are a protrusion amount a of 4 mm < a < 5.2 mm and a radial width b of 1 mm < b < 1.5 mm. Note that these recommended dimensions are merely examples and will vary depending on the outer diameter of the rotating shaft 11 and the inner diameter of the housing 12.

[0028] The operation of the current-carrying unit 1 according to the first embodiment will now be described. A rotating shaft 11, such as a motor shaft, is inserted through the axis of this current-carrying unit 1. When the inner diameter surface of the current-carrying member 4, which is biased toward the rotating shaft 11 by the biasing force of the elastic member 5, comes into sliding contact with the rotating shaft 11, this inner diameter surface gradually wears down. However, since the current-carrying member 4 is always biased toward the rotating shaft 11 by the elastic member 5, the contact state (current-carrying state) between the rotating shaft 11 and the current-carrying member 4 is maintained. Furthermore, when vibration or shock acts on the current-carrying unit 1 during or after assembly and the current-carrying member 4 is displaced toward the inner diameter, the protruding portion 6a, which serves as a fall-prevention portion 6 and is extended from the current-carrying member 4, and the claw portion 19, which is connected to the flange portion 18 of the retainer 14, catch on each other in the circumferential direction, preventing further displacement of the current-carrying member 4 toward the inner diameter.

[0029] In the first embodiment, the energizing unit 1 and bearing unit A are configured to dissipate the electric charge generated on the rotating shaft 11 to the housing 12 via the energizing member 4 and the case body 3, thereby preventing electrolytic corrosion of the bearing 2 provided between the rotating shaft 11 and the housing 12. Furthermore, the protrusion 6a formed on the energizing member 4 catches on the claw portion 19 connected to the flange portion 18 of the retainer 14 in the circumferential direction, thereby preventing displacement. This allows the energizing unit 1 to be easily assembled without the energizing member 4 falling off towards the inner diameter side due to vibration or shock during or after assembly.

[0030] Furthermore, in the first embodiment, the current-carrying unit 1 is configured such that multiple current-carrying members 4 are provided along the circumferential direction of the case body 3. Therefore, even if the rotating shaft 11 becomes eccentric in one direction due to vibrations associated with its rotation, and one current-carrying member 4 fails to follow the eccentricity, resulting in poor contact, the current-carrying state is maintained by the other current-carrying members 4 arranged in the same direction. Moreover, even if the current-carrying state of one current-carrying member 4 is impaired due to damage or other reasons, the other current-carrying members 4 can cover the current-carrying state, thus ensuring stable current-carrying performance. In addition, since the current-carrying members 4 are made of conductive materials composed of metal, carbon, conductive resin, rubber, ceramics, or composite materials thereof, the current-carrying performance of the current-carrying unit 1 can be ensured with a simple configuration.

[0031] Furthermore, in the current-carrying unit 1 according to the first embodiment, the elastic member 5 is an annular member provided across the outer peripheral groove 20 formed on the outer diameter side end of the plurality of current-carrying members 4, so that the plurality of current-carrying members 4 can be biased toward the inner diameter side all at once with a simple configuration.

[0032] In the above description, the inner diameter surface of the protruding portion 6a is curved to follow the outer edge of the claw portion 19. However, even if the inner diameter surface of the protruding portion 6a is straight, as shown in the modified example in Figure 6, the same effects and advantages as described above can be achieved.

[0033] Furthermore, while the above uses an annular garter spring provided across the outer circumferential grooves 20 of multiple current-carrying members 4 as the elastic member 5, as shown in the modified example in Figures 7 and 8, a metal elastic spring (compression coil spring) can also be used as the elastic member 5, provided between the spring seat 21 formed on the outer diameter side end of the current-carrying member 4 and the case body 3, to individually bias the current-carrying members 4 radially inward. According to this modified example, the current-carrying unit 1 can secure multiple current-carrying routes, including a current-carrying route in which current flows directly from the current-carrying member 4 to the case body 3, and a current-carrying route in which current flows from the current-carrying member 4 to the case body 3 via the elastic member 5, thereby enabling more stable current-carrying performance.

[0034] Figures 9 to 11 show a current-carrying unit 1 according to a second embodiment of the present invention. The current-carrying unit 1 according to the second embodiment is similar to the current-carrying unit 1 according to the first embodiment in that it has a case body 3, a current-carrying member 4, an elastic member 5, and a fall-prevention part 6, but the configuration of the case body 3 (particularly the retainer 14) and the fall-prevention part 6 differs. The differences will be explained below.

[0035] The retainer 14 of the energizing unit 1 according to the second embodiment has a cylindrical outer ring portion 17 having a surface normal facing radially, and a flange portion 18 extending radially inward from the other axial end of the outer ring portion 17 and having a surface normal facing axially. A claw portion 19 is provided along the inner edge of the flange portion 18, extending toward one axial end along its entire circumference. Concave notches 22 are formed at four locations in the circumferential direction of the claw portion 19. In the portions where these notches 22 are formed, the axial width of the claw portion 19 is narrowed.

[0036] A projection 6b, which serves as a fall prevention part 6, is integrally provided on the other axial end of the outer diameter side of the conductive member 4, extending axially toward the flange portion 18 of the retainer 14. The conductive member 4 is provided so as to be radially movable within a notch 22 formed in the claw portion 19 of the retainer 14. The inner diameter surface of the projection 6b is curved to follow the outer edge of the claw portion 19.

[0037] In the above configuration, when the axial width of the conductive member 4, including the protruding portion 6b, is W2, and the amount of protrusion of the protruding portion 6b from the axial end of the conductive member 4 is a (see Figure 10), the design is such that the ratio a / W2 of the two falls within the range of 1 / 5 to 1 / 4, similar to the conductive unit 1 according to the first embodiment. If the ratio a / W2 is less than 1 / 5, the engagement of the protruding portion 6b with the claw portion 19 in the notch portion 22 becomes insufficient, and if it is greater than 1 / 4, the difficulty of machining the conductive member 4 increases, so it is preferable to keep it within the above range.

[0038] Furthermore, when the radial width of the protrusion 6b is b, the radial width of the conductive member 4 on the inner side of the protrusion 6b is c, and the radius of the elastic member 5 is r (see Figure 10), it is preferable that the relationship b ≥ r holds. By doing so, sufficient strength of the protrusion 6a can be ensured against the elastic force of the elastic member 5. Moreover, it is preferable to make the radial width b of the protrusion 6b as small as possible with respect to the total radial width b + c of the conductive member 4, while making the radial width c of the conductive member 4 on the inner side of the protrusion 6b as large as possible. By doing so, a sufficient wear tolerance can be ensured when the conductive member 4 slides against the rotating shaft 11 and wears down.

[0039] The energizing unit 1 according to the second embodiment takes into account recommended dimensions to ensure compatibility with conventional energizing units (for example, recommended outer diameter during assembly: φ53.3 mm, recommended width: 4.4 mm, inner diameter when mounting the rotating shaft 11 (a typical e-Axle motor shaft): φ35 mm), and for example, the axial width W1 of the energizing member 4 can be set to 15.7 mm, height 4.5 mm, and axial width W2 of the energizing member 4 to 2.5 mm. In this case, considering the range of the ratio a / W2, the relationship between b≧r, and the sizes of b and c relative to the total radial width b+c of the energizing member 4, the recommended dimensions of the protruding portion 6b are: protrusion amount a is 0.7 mm < a < 0.8 mm, radial width b is 1 mm < b < 1.5 mm, and radial width c of the energizing member 4 on the inner diameter side of the protruding portion 6b is 3 mm < c < 3.5 mm. Note that these recommended dimensions are merely examples and will vary depending on the outer diameter of the rotating shaft 11, the inner diameter of the housing 12, etc.

[0040] In the second embodiment, the current-carrying unit 1 exhibits the same corrosion-preventive effect on the bearing 2 as in the first embodiment, and the projection 6b formed on the current-carrying member 4 catches in the axial direction on the claw portion 19 connected to the flange portion 18 of the retainer 14, thereby preventing displacement. As a result, the current-carrying member 4 does not fall off to the inner diameter side due to vibration or shock during or after assembly of the current-carrying unit 1, and the current-carrying unit 1 can be easily assembled.

[0041] The energization unit 1 according to the third embodiment of the present invention is shown in FIGS. 12 to 14. The energization unit 1 according to the third embodiment is common with the energization unit 1 according to the first embodiment in that it has a case main body portion 3, an energization member 4, an elastic member 5, and a detachment prevention portion 6, but the configurations of the case main body portion 3 (particularly the retainer 14) and the detachment prevention portion 6 are different. Hereinafter, the differences will be described.

[0042] The retainer 14 of the energization unit 1 according to the third embodiment has a cylindrical outer peripheral ring portion 17 having a surface normal facing in the radial direction, and a flange portion 18 extending radially inward from the other end side in the axial direction of the outer peripheral ring portion 17 and having a surface normal facing in the axial direction. At the inner edge of the flange portion 18, claw portions 19 extending toward the one end side in the axial direction are continuously provided over the entire circumference. Concave notch portions 22 are formed at four locations in the circumferential direction of the claw portions 19. At the portion where the notch portions 22 are formed, the axial width of the claw portions 19 is narrowed.

[0043] At the circumferential end portion on the outer diameter side of the energization member 4, projecting portions 6a as the detachment prevention portion 6 extend toward both sides in the circumferential direction, and at the other end side in the axial direction on the outer diameter side, a projecting portion 6b as the detachment prevention portion 6 extending axially toward the flange portion 18 of the retainer 14 are integrally extended with the energization member 4, respectively. The energization member 4 is provided movably in the radial direction within the notch portion 22 formed in the claw portion 19 of the retainer 14. The inner diameter surfaces of the projecting portions 6a and 6b are curved so as to follow the outer peripheral edge of the claw portion 19. Since the recommended dimensions of the projecting portions 6a and 6b can be determined in the same manner as described in the first and second embodiments, the description thereof is omitted.

[0044] The energization unit 1 according to the third embodiment exhibits the electrolytic corrosion prevention effect of the bearing 2 in the same manner as the energization unit 1 according to the first embodiment and the like, and the projecting portions 6a and 6b formed on the energization member 4 are hooked in both the circumferential direction and the axial direction by the claw portions 19 continuously provided on the flange portion 18 of the retainer 14 to prevent displacement. Therefore, the energization member 4 does not drop to the inner diameter side due to vibration or impact during or after the assembly of the energization unit 1, and the energization unit 1 can be assembled simply.

[0045] The energization unit 1 according to the fourth embodiment of the present invention is shown in FIGS. 15 and 16. The energization unit 1 according to the fourth embodiment has a case main body portion 3, an energization member 4, an elastic member 5, and a detachment prevention portion 6, which is common to the energization unit 1 according to the first embodiment, but the configuration of the detachment prevention portion 6 is different. Hereinafter, the differences will be described.

[0046] In the energization unit 1 according to the fourth embodiment, a holding member 23 is fixed to the outer side in the radial direction of the energization member 4. The holding member 23 is made of a material such as metal or resin. On both sides in the circumferential direction of the holding member 23, a protruding portion 6c as a detachment prevention portion 6 is integrally extended with the holding member 23 so as to protrude in the circumferential direction from the circumferential end portion of the energization member 4. An outer peripheral groove 20 is formed on the outer peripheral edge of the holding member 23. The elastic member 5 is stretched across the outer peripheral groove 20. The holding member 23 has a substantially Y shape in a cross-sectional view, and its inner diameter portion is inserted into the axial center portion of the outer diameter surface of the energization member.

[0047] The energization member 4 is provided so as to be movable in the radial direction within a notch portion 22 formed in the claw portion 19 of the retainer 14. The inner diameter surface of the protruding portion 6c is curved so as to follow the outer peripheral edge of the claw portion 19. The energization member 4 is provided so as to be movable in the radial direction between the claw portions 19 adjacent in the circumferential direction and connected to the flange portion 18 of the retainer 14.

[0048] In the energization unit according to the fourth embodiment, when the width of the energization member 4 in the axial direction is W1 and the protruding amount of the protruding portion 6c from the circumferential end portion of the energization member 4 is e (see FIG. 15), the value of the ratio e / W1 of the two is designed to be 1 / 5 or more. If the value of the ratio e / W1 is less than 1 / 5, the engagement of the protruding portion 6c with the claw portion is insufficient, so it is preferable to be within the above range. Further, when the axial width of the energization member 4 is W2 and the axial width of the holding member 23 is f (see FIG. 15), it is preferable that the magnitude relationship of W2>f is established. By doing so, it is possible to prevent the holding member 23 from protruding from the axial end portion of the energization member 4 and ensure the contact state between the case main body portion 3 (outer ring portion 13) and the energization member 4.

[0049] The power supply unit 1 according to the fourth embodiment takes into account recommended dimensions to ensure compatibility with conventional power supply units (for example, recommended outer diameter during assembly: φ53.3 mm, recommended width: 4.4 mm, inner diameter when the rotating shaft 11 (a typical e-Axle motor shaft) is mounted: φ35 mm), and for example, the width W1 of the power supply member 4 can be 15.7 mm, the height 4.5 mm, and the width W2 = 2.5 mm. In this case, considering the range of the ratio e / W1 and the relationship between W2 > f, the recommended dimensions of the protruding portion 6c are such that the protrusion amount e is 4 mm < e and the axial width f of the holding member 23 is f < 2.5 mm. Note that these recommended dimensions are merely examples and will vary depending on the outer diameter of the rotating shaft 11 and the inner diameter of the housing 12.

[0050] In the fourth embodiment, the current-carrying unit 1 exhibits the same corrosion-preventive effect on the bearing 2 as in the current-carrying unit 1 of the first embodiment, and the projection 6c formed on the retaining member 23 catches on the claw portion 19 connected to the flange portion 18 of the retainer 14 in the circumferential direction, thereby preventing displacement. As a result, the current-carrying member 4 does not fall off to the inner diameter side due to vibration or shock during or after the assembly of the current-carrying unit 1, and the current-carrying unit 1 can be easily assembled. Moreover, by making the current-carrying member 4 and the retaining member 23 separate components, the shape of the current-carrying member 4, which is relatively difficult to process, can be simplified, which may reduce processing costs.

[0051] In the fourth embodiment described above, the retaining member 23 is substantially Y-shaped in cross-section, and its inner diameter portion is inserted into the axial center of the outer diameter surface of the current-conducting member 4. However, as shown in Figure 17, the retaining member 23 can also be configured to straddle the outer diameter surface of the current-conducting member 4 in cross-section. This configuration improves the rigidity of the retaining member 23 when the elastic force of the elastic member 5 acts upon it.

[0052] In the embodiments described above, the energizing unit 1, which is used separately from the bearing 2, was described. However, as shown in Figure 18, the outer peripheral ring portion 15 of the outer ring portion 13 can be extended to the outer diameter side of the outer ring 7 of the bearing 2, and the energizing unit 1 and the bearing 2 can be integrated into a single bearing unit A. In this way, it may be possible to reduce the weight and width of the bearing unit A, and existing bearings can be smoothly replaced with the bearing unit A according to the present invention.

[0053] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope of equivalents of the claims are intended.

[0054] 1. Power supply unit 2. Bearing 3. Case body 4. Power supply member 5. Elastic member 6. Anti-dropping part 6a, 6b, 6c. Protruding part 7. Outer ring 8. Inner ring 9. Rolling element 13. Outer ring part 14. Retainer 19. Claw part 22. Notch part 23. Holding member A. Bearing unit

Claims

1. A conductive annular case body (3) having an opening formed radially inward; a conductive current-carrying member (4) provided within the case body (3) and protruding radially inward from the opening of the case body (3); an elastic member (5) that biases the current-carrying member (4) radially inward; and a fall prevention part (6) that prevents the current-carrying member (4) from falling out of the case body (3).

2. The current-carrying unit according to claim 1, wherein the case body portion (3) has an annular outer ring portion (13) and a retainer (14) having a claw portion (19) that fits into the outer ring portion (13) from the axial direction and extends in the axial direction, and the fall-prevention portion (6) is a projection portion (6a, 6b) extending from the current-carrying member (4) in at least one of its circumferential or axial direction, and the current-carrying member (4) is prevented from falling out by the projection portion (6a, 6b) coming into contact with the claw portion (19) when the current-carrying member (4) is displaced radially inward.

3. The current-carrying unit according to claim 1, wherein the case body portion (3) has an annular outer ring portion (13) and a retainer (14) having a claw portion (19) that fits into the outer ring portion (13) from the axial direction and extends in the axial direction, a holding member (23) is fixed to the radially outer side of the current-carrying member (4), and the fall-prevention portion (6) is a projection portion (6c) extending from the holding member (23) so as to project from the current-carrying member (4) in at least one of its circumferential or axial directions, and the current-carrying member (4) is prevented from falling out by the projection portion (6c) contacting the claw portion (19) when the current-carrying member (4) is displaced radially inward.

4. The current-carrying unit according to claim 1, wherein the current-carrying member (4) includes a conductive material composed of metal, carbon, or a conductive resin, rubber, ceramics, or a composite material thereof.

5. The energizing unit according to claim 1, wherein a plurality of the energizing members (4) are provided along the circumferential direction of the case body (3).

6. The current-carrying unit according to claim 5, wherein the elastic member (5) is an annular member provided across the outer diameter ends of a plurality of current-carrying members (4), or a metallic elastic spring interposed between the outer diameter ends of the current-carrying members (4) and the case body (3) to individually bias the current-carrying members (4) radially inward.

7. A bearing unit comprising: an energizing unit (1) according to any one of claims 1 to 6; and a bearing (2) having an outer ring (7), an inner ring (8) disposed on the inner diameter side of the outer ring (7), and rolling elements (9) provided between the outer ring (7) and the inner ring (8), wherein the outer ring (7) is disposed so as to abut the case body (3).

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