Current-carrying unit and electric motor

Abstract

To provide a current-carrying unit of which configuration capable of being used to electrically connect a shaft and a housing is simplified.SOLUTION: A current-carrying unit includes in one series: a conductive annual member 2 having a recess portion 2a; an elastic member 3 sandwiched into the recess portion 2a; and a conductive member 4 having a base end portion 4a sandwiched between the recess portion 2a and the elastic member 3 and a tip end portion 4b extending hollowly from the recess portion 2a and the elastic member 3, in which the base end portion 4a and the elastic member 3 of the conductive member 4 are fixed by an elastic restoring force of the elastic member 3.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electric current-carrying unit disposed between a shaft and a housing surrounding the shaft in order to electrically connect the shaft and the housing, and to an electric motor using the electric current-carrying unit. [Background technology]

[0002] For example, the shaft of the rotor of the electric motor is rotatably supported by rolling bearings such as ball bearings. In recent years, electric motors have been driven by inverter control to operate efficiently. In particular, in the case of electric motors mounted on e-axle units in which the electric motor, inverter, and reducer are integrated, it is necessary to use as small an electric motor as possible efficiently over a wide range due to the ease of mounting, and more precise control is performed.

[0003] Conventionally, shaft voltages and currents are generated on the shaft, which can cause radio noise and electric discharges between the rolling elements and raceways of the rolling bearings that support the shaft, resulting in electrolytic corrosion of the rolling elements. As a measure to prevent these problems, the shaft is earthed via a current path that does not pass through the rolling bearings that support the shaft. To achieve this earthing, the housing is electrically connected to the earth, and an electric current unit is installed between the housing and the shaft.

[0004] The current-carrying unit disclosed in Patent Document 1 includes a pair of conductive annular members facing each other in the axial direction, a cup or the like that holds the outer periphery of the conductive annular members, and a number of conductive fibers fixed between the conductive annular members. Each conductive fiber has a base end sandwiched between the conductive annular members and a tip end that protrudes radially inward from between the conductive annular members and extends into the air. The many conductive fibers are distributed all around the circumference. As a specific means for fixing the base end of each conductive fiber to each conductive annular member, a conductive adhesive and an adhesive tape have been proposed. When the cup of the current-carrying unit is fitted into the inner circumference of the housing of the electric motor and the tip ends of the many conductive fibers are brought into contact with the shaft, the housing and the shaft can be electrically connected by the current-carrying unit. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 8,199,453 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when an adhesive or adhesive tape is used as a means for fixing the base end of each conductive fiber between a pair of conductive ring members, as in the current-carrying unit of Patent Document 1, it becomes important to prevent separation of the pair of conductive ring members in order to prevent peeling of the conductive ring members. If a structure is used in which the outer periphery of the pair of conductive ring members is restrained by crimping a cup, it is possible to prevent separation of the pair of conductive ring members, but there is a problem in that the structure becomes complicated in that parts for restraining and a crimping process are required.

[0007] In view of the above background, an object of the present invention is to simplify the configuration of an energization unit that can be used to electrically connect a shaft and a housing. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention adopts configuration 1, which is a conductive unit comprising: a conductive annular member having a recess; an elastic member fitted into the recess; a conductive member having a base end sandwiched between the recess and the elastic member; and a tip end extending into hollow from the recess and between the elastic member, wherein the base end of the conductive member and the elastic member are fixed by the elastic restoring force of the elastic member.

[0009] According to the above configuration 1, the conductive member receives an elastic restoring force from the elastic member between the recess of the conductive ring member and the elastic member, thereby realizing the fixing of the conductive member and the elastic member, and eliminating the need to restrain the elastic member and the conductive ring member from being separated by a cup or the like, and the current-carrying unit can be configured simply. The conductive ring member of the current-carrying unit can be fitted into a housing or a shaft, and the tip of the conductive member extending into the air from between the recess of the conductive ring member and the elastic member is brought into contact with the opposite shaft or housing, thereby electrically connecting the shaft and the housing. When the conductive ring member is fitted into the housing, a part or all of the outer diameter of the conductive ring member is provided in the housing of the bearing.

[0010] In the above configuration 1, a configuration 2 can be adopted in which the conductive member has a plurality of the tip portions extending from both sides of the base end portion.

[0011] According to the above configuration 2, the number of tip portions per conductive member can be increased, and the number of current paths between the shaft and the housing can be increased.

[0012] In the above configuration 1 or 2, configuration 3 can be adopted in which the recess of the conductive ring-shaped member is a groove portion extending circumferentially on the inner or outer circumference of the conductive ring-shaped member, and the elastic member has a ring shape that is divided at one point in the circumferential direction.

[0013] According to the above configuration 3, one or more conductive members can be arranged over a wide area in the circumferential direction along the recess of the conductive annular member, and can be easily fixed by the elastic restoring force in the radial direction of one elastic member.

[0014] In the above configuration 3, configuration 4 can be adopted in which at least one of the recess of the conductive annular member and the surface region of the elastic member that radially sandwich the base end of the conductive member is inclined relative to the radial direction.

[0015] According to the above configuration 4, the inclination of the surface area of ​​at least one of the elastic member and the recess, which sandwich the base end of the conductive member in the radial direction, can suppress free movement of the elastic member in the axial direction.

[0016] In the above configuration 3 or 4, a configuration 5 can be adopted in which a hole is formed that penetrates between the inner and outer periphery of the conductive annular member and intersects with the recess.

[0017] According to the above-mentioned configuration 5, the air in the recess of the conductive ring member can be sucked through the hole. Therefore, when assembling the current-carrying unit, the conductive member, which has been placed in advance at a predetermined position relative to the conductive ring member, can be temporarily attached to the predetermined position by being attracted to the conductive ring member by the above-mentioned suction. Therefore, it becomes easy to appropriately sandwich the conductive member between the recess of the conductive ring member and the elastic member.

[0018] In any one of the above configurations 3 to 5, configuration 6 can be adopted, in which the conductive annular member has a cylindrical surface along the axial and circumferential directions at a position adjacent to the recess, and a step portion protruding radially from the cylindrical surface.

[0019] According to the sixth aspect, when assembling the current-carrying unit, the conductive member can be positioned at an appropriate radial position by the cylindrical surface of the conductive annular member, and the conductive member can be positioned at an appropriate axial position by the step of the conductive annular member, which makes it easy to appropriately sandwich the conductive member between the recess of the conductive annular member and the elastic member.

[0020] In any one of the above configurations 3 to 6, a configuration 7 can be adopted in which an adhesive material is disposed between the conductive member and the conductive annular member.

[0021] According to the above-mentioned configuration 7, when assembling the current-carrying unit, the conductive member is temporarily attached in a predetermined position to the conductive ring-shaped member with an adhesive material, and then the elastic member is fitted into and fixed in the recess, so that a current-carrying unit can be obtained in which the base end and tip end of the conductive member are appropriately positioned.

[0022] In any one of the above configurations 3 to 7, configuration 8 can be adopted, in which the recess of the conductive ring-shaped member is formed on the inner circumference of the conductive ring-shaped member, and the conductive ring-shaped member has a flange portion on the outer circumference of the conductive ring-shaped member.

[0023] According to the above configuration 8, when the conductive annular member is fitted into the housing and the current-carrying unit is assembled so that the conductive member contacts the shaft, the flange portion of the conductive annular member can be axially locked by the housing, so that the axial position of the conductive annular member can be appropriately determined.

[0024] In any one of the above configurations 1 to 8, a configuration 9 can be adopted in which the conductive member is made of conductive fiber.

[0025] In any one of the above configurations 1 to 8, a configuration 10 can be adopted in which the conductive member is made of a conductive resin.

[0026] By adopting configuration 11, which is an electric motor comprising an energizing unit described in any one of configurations 1 to 10 above, a shaft, a housing surrounding the shaft, and a rolling bearing supporting the shaft relative to the housing, in which the conductive annular member is fitted into one of the shaft and the housing and the tip of the conductive member is in contact with the other member, it is possible to electrically connect the shaft and the housing with a simple energizing unit and prevent electrical corrosion of the rolling bearing, etc.

[0027] In the above configuration 11, a configuration 12 can be adopted in which the conductive annular member is fixed to the one of the members by screwing it to the one of the members.

[0028] According to the twelfth aspect, the conductive annular member can be removed from the one member by releasing the screw engagement between the one member and the conductive annular member, which improves the replaceability of the current-carrying unit.

[0029] In the above configuration 11, a configuration 13 can be adopted in which a screw member is provided for fastening the conductive annular member and the one member in the axial direction.

[0030] According to the thirteenth aspect, the conductive annular member can be axially removed from one of the members by removing the screw member, which improves the replaceability of the current-carrying unit.

[0031] In the above configuration 11, a configuration 14 can be adopted, which includes a bracket connected to one end side of the housing and a spring member axially sandwiched between the conductive annular member described in the above configuration 8 and the bracket, the conductive annular member being fitted into the housing, and the housing having a step portion that axially engages the flange portion of the conductive annular member against the elastic restoring force of the spring member.

[0032] According to the above configuration 14, the conductive annular member fitted to the housing can be fixed by the bracket, the spring member, the flange portion, and the step portion of the housing, and the conductive annular member can be pulled out of the housing in the axial direction by removing the bracket from the housing, which improves the replaceability of the current-carrying unit.

[0033] The current-carrying unit of the present invention may be disposed between the bearing and the shaft end, or between the bearing and the rotor. When disposed between the bearing and the shaft end, in consideration of preventing electrolytic corrosion of the bearing, it is preferable to provide the current-carrying unit within 50 mm of the bearing, and more preferably within 30 mm of the bearing. Effect of the Invention

[0034] As described above, by employing the above configuration 1, the present invention can simplify the configuration of the current-carrying unit that can be used to electrically connect the shaft and the housing. [Brief description of the drawings]

[0035] [Figure 1]FIG. 1 is a cross-sectional view showing an electric motor including a current-carrying unit according to a first embodiment of the present invention; [Diagram 2] Enlarged view of the conductive material in Figure 1 [Diagram 3] FIG. 2 is an exploded perspective view of a current-carrying unit according to the first embodiment; [Figure 4] 1 is a side view of a current-carrying unit according to a first embodiment; [Diagram 5] FIG. 11 is a cross-sectional view showing an electric motor including a current-carrying unit according to a second embodiment of the present invention. [Figure 6] FIG. 11 is a cross-sectional view showing an electric motor including a current-carrying unit according to a third embodiment of the present invention. [Figure 7] FIG. 11 is a cross-sectional view showing an electric motor including a current-carrying unit according to a fourth embodiment of the present invention. [Figure 8] FIG. 11 is a cross-sectional view showing a state in which a gap occurs in the axial direction between the conductive member and the elastic member of the current-carrying unit according to the first embodiment of the present invention; [Figure 9] FIG. 13 is a cross-sectional view showing an electric motor including a current-carrying unit according to a fifth embodiment of the present invention. [Figure 10] FIG. 13 is a cross-sectional view showing the arrangement of conductive members during assembly of an energizing unit according to a sixth embodiment of the present invention; [Figure 11] FIG. 13 is a cross-sectional view showing the arrangement of conductive members during assembly of an energizing unit according to a seventh embodiment of the present invention; [Figure 12] FIG. 13 is a cross-sectional view showing an electric motor including a current-carrying unit according to an eighth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] BEST MODE FOR CARRYING OUT THE PRESENTLY PREFERRED EMBODIMENTS A current-carrying unit and an electric motor according to a first embodiment as one example of the present invention will be described with reference to the accompanying drawings, FIGS. 1 to 4. FIG.

[0037] The current-carrying unit 1 shown in FIG. 1 is configured to be attached to a housing 11 of an electric motor 10 so as to electrically connect a shaft 12 of the electric motor 10 and the housing 11. As shown in FIG.

[0038] The electric motor 10 includes a stator 13 accommodated in a housing 11, a rotor 14 attached to a shaft 12, and rolling bearings 15, 16 that support the shaft 12 relative to the housing 11, and is driven and controlled by an inverter (not shown, same applies below). The electric motor 10 is, for example, an in-vehicle electric motor that serves as a vehicle drive source for an e-axle unit or the like.

[0039] Hereinafter, the direction along the central axis of shaft 12 (not shown, same below) will be referred to as the "axial direction", the direction perpendicular to that central axis will be referred to as the "radial direction", and the circumferential direction going around the central axis will be referred to as the "circumferential direction".

[0040] The shaft 12 serves as the central axis of rotation of the rotor 14, and rotates together with the rotor 14 due to torque generated by the electromagnetic action of the stator 13 and the rotor 14 working together.

[0041] The housing 11 radially surrounds and covers the shaft 12, the rolling bearings 15, 16 for supporting the shaft, the stator 13, and the rotor 14, and supports the rolling bearings 15, 16 for supporting the shaft in the radial direction.

[0042] The shaft 12 and the housing 11 are each electrically conductive and generally made of one or more metal members.

[0043] The housing 11 is a part that serves as a reference potential with respect to the potential at the shaft 12. The housing 11 is generally electrically connected to the body of the machine, the ground, or the like, to which the charge is to be released. The housing 11 may further accommodate mechanical elements that are driven by the shaft 12, in addition to the rolling bearings 15, 16, the rotor 14, and the stator 13. For example, in the case of an e-axle, the housing may be configured to also accommodate a reducer that is connected to the shaft, and this may be electrically connected to the vehicle body (body earth circuit).

[0044] The housing 11 is a cylindrical body that is open at both axial ends. A bracket 17 is detachably coupled to one axial end of the housing 11.

[0045] Each of the rolling bearings 15, 16 includes an inner ring fitted onto the shaft 12, an outer ring fitted onto the inner periphery of the housing 11, a plurality of rolling elements arranged between the raceway surfaces of the inner and outer rings, and a cage for holding the rolling elements. Generally, ball bearings are used as each of the rolling bearings 15, 16.

[0046] This conductive unit 1 consists of a conductive annular member 2 fitted into a housing 11, an elastic member 3 attached to the conductive annular member 2, and a plurality of conductive members 4 sandwiched between the conductive annular member 2 and the elastic member 3.

[0047] The conductive annular member 2 is made of a tubular member that goes around the axis without any seams in the circumferential direction. The direction in which the axis extends corresponds to the axial direction. The conductive annular member 2 is in the shape of a ring having inner and outer circumferences along the circumferential direction. Note that FIG. 1 shows an ideal state in which the axis of the conductive annular member 2 and the central axis of the shaft 12 are arranged concentrically. The conductive annular member 2 can also be changed to an annular shape that is divided at one point in the circumferential direction.

[0048] The conductive annular member 2 is made of a conductive material. Examples of the conductive material include metal, carbon, conductive resin, etc. Examples of the metal include iron-based materials, copper-based materials, aluminum alloys, etc. The conductive resin is a composite material in which a conductive additive such as a powdered or fibrous metal or carbon is mixed with a base resin (matrix). In particular, when the mechanical strength of the conductive resin is required, a composite material in which a fibrous conductive additive is mixed with a base resin may be used.

[0049] The conductive annular member 2 is fixed to the housing 11 by press-fitting the outer periphery of the conductive annular member 2 into the inner periphery of the housing 11 from one axial end side.

[0050] 2 and 3, the conductive annular member 2 has a recess 2a formed on the inner circumference of the conductive annular member 2. The recess 2a is a groove portion that extends circumferentially with a radial depth from a cylindrical surface 2b formed on the inner circumference of the conductive annular member 2 on the inner circumference of the conductive annular member 2. The recess 2a has a constant groove cross-sectional shape and continues over the entire circumferential length of the conductive annular member 2. The recess 2a is open radially inward and has a groove bottom surface along the axial direction.

[0051] The elastic member 3 is fitted into the recess 2a. The elastic member 3 has an annular shape that is divided at one point in the circumferential direction. For example, a C-shaped retaining ring can be used as such an elastic member 3. The elastic member 3 is fitted into the recess 2a in a state in which the elastic member 3 is reduced in diameter compared to the cylindrical surface 2b of the conductive annular member 2. A radial tightening margin is set between the recess 2a and the elastic member 3 so that the elastic member 3 fitted into the recess 2a generates a predetermined or greater radial elastic restoring force.

[0052] The conductive member 4 has a base end 4a sandwiched between the recess 2a and the elastic member 3, and a tip end 4b extending from between the recess 2a and the elastic member 3 into the air, in series.

[0053] 3 and 4, the multiple conductive members 4 are arranged over an angular range greater than 180° in the circumferential direction. It is also possible to modify so that only one conductive member 4 that is long in the circumferential direction is sandwiched between the recess 2a and the elastic member 3. In any case, the relationship between the circumferential range in which one or more conductive members 4 are arranged and the circumferential length of the elastic member 3 should be determined so that all of the conductive members 4 provided in this current-carrying unit 1 can be sandwiched between one elastic member 3 and the recess 2a.

[0054] 2, the base end 4a of the conductive member 4 is sandwiched radially between the outer periphery of the elastic member 3 and the groove bottom surface of the recess 2a due to the elastic restoring force of the elastic member 3. The groove width of the recess 2a is set to be larger than the sum of the axial width of the elastic member 3 and the axial width of the base end 4a of the conductive member 4 to allow for manufacturing errors. The base end 4a of the conductive member 4 and the elastic member 3 are fixed to the conductive annular member 2 by the elastic restoring force of the elastic member 3 fitted into the recess 2a so as to sandwich the base end 4a.

[0055] The conductive member 4 has a plurality of tip portions 4b extending from both sides of the base end portion 4a. The first tip portion 4b extending from one axial end side of the base end portion 4a of the conductive member 4 and the second tip portion 4b extending from the opposite side of the axial end side of the base end portion 4a protrude radially inward from the conductive annular member 2 and the elastic member 3. As shown in Figs. 1 and 2, when the current-carrying unit 1 is disposed between the housing 11 and the shaft 12, each tip portion 4b of each conductive member 4 contacts the shaft 12. In Fig. 1, the tip portion 4b is shown as a straight line in order to show the radial dimensional relationship between the tip portion 4b of the conductive member 4 and the shaft 12, but in reality, the tip portion 4b is bent due to the relative axial sliding contact of the tip portion 4b with the shaft 12.

[0056] The conductive member 4 is made of a conductive material.

[0057] As the conductive member 4, for example, a conductive fiber, a conductive sheet, or the like can be adopted.

[0058] When assembling the current-carrying unit 1 using a conductive member formed in a straight filament or flat sheet shape, a plurality of tip portions 4b can be formed by utilizing a process of fitting the elastic member 3 into the recess 2a. For example, as shown in Fig. 3, in a state where both ends of the axial length of the conductive member 4 arranged along the axial direction are supported in the radial direction by the cylindrical surface 2b of the conductive ring-shaped member 2 and the axial position of the conductive member 4 is determined so that the central portion of the axial length of the conductive member 4 faces the recess 2a in the radial direction, the elastic member 3 is fitted into the recess 2a from a position closer to the inside in the radial direction than the conductive member 4, whereby the conductive member 4 is received in the recess 2a and pushed outward in the radial direction by the elastic member 3, and is deformed into a folded shape as shown in Fig. 2. As a result, the aforementioned central portion of the conductive member 4 becomes a base end portion 4a that is radially sandwiched between the groove bottom surface of the recess 2a and the outer periphery of the elastic member 3, and the aforementioned both end portions of the conductive member 4 become a first tip portion 4b and a second tip portion 4b that protrude radially inward from between the recess 2a and the elastic member 3 and extend into the hollow.

[0059] Examples of the conductive fibers that can be used as the conductive member 4 include carbon fibers, metal fibers, and conductive resin fibers. Examples of the conductive sheets that can be used as the conductive member 4 include conductive resin sheets.

[0060] When the conductive member is formed from a conductive resin, for example, conductive PTFE, which is a composite material using fluororesin as the base resin, can be used. The method of forming the conductive resin is not particularly limited, but a composite material in which a fibrous conductive additive is mixed with a base resin may be used to maintain the strength and rigidity while ensuring the conductivity of the conductive member 4. The method of forming the conductive member from the composite material may be RTM (Resin Transfer Molding) molding or SCM (Sheet Molding Compound) molding.

[0061] It is also possible to adopt a conductive member 4 made of a molded part having a folded shape as shown in FIG. 2, fit the molded part into the recess 2a before the elastic member 3, and then pass the elastic member 3 between the multiple tip portions 4b and fit it into the recess 2a, thereby sandwiching the conductive member 4 between the elastic member 3 and the recess 2a.

[0062] The current-carrying unit 1 shown in Figures 1 to 4 is as described above, and particularly includes the conductive annular member 2 having a recess 2a, the elastic member 3 fitted into the recess 2a, and the conductive member 4 having, in series, a base end 4a sandwiched between the recess 2a and the elastic member 3, and a tip end 4b extending into the air from between the recess 2a and the elastic member 3. The base end 4a of the conductive member 4 and the elastic member 3 are fixed by the elastic restoring force of the elastic member 3, so that the recess 2a receives the elastic restoring force of the elastic member 3 which sandwiches the base end 4a of the conductive member 4 between itself and the recess 2a, thereby realizing the fixation of the conductive member 4 and the elastic member 3. This eliminates the need to restrain the separation of the elastic member 3 and the conductive annular member 2 with a cup or the like, and allows the current-carrying unit 1 to have a simple configuration. The conductive ring-shaped member 2 of the current-carrying unit 1 is fitted into the housing 11, and the tip portion 4b of the conductive member 4 extending into the air from between the recessed portion 2a of the conductive ring-shaped member 2 and the elastic member 3 is brought into contact with the opposite shaft 12, thereby allowing the current-carrying unit 1 to be used to electrically connect the shaft 12 and the housing 11. In other words, according to this current-carrying unit 1, the configuration of the current-carrying unit 1 that can be used to electrically connect the shaft 12 and the housing 11 can be simplified.

[0063] In addition, since the conductive member 4 of this current-carrying unit 1 has multiple tip ends 4b extending from both sides of the base end 4a, the number of tip ends 4b per conductive member 4 can be increased, thereby increasing the number of current-carrying paths between the shaft 12 and the housing 11.

[0064] In addition, in this conductive unit 1, the recess 2a of the conductive ring-shaped member 2 consists of a groove portion extending circumferentially around the inner circumference of the conductive ring-shaped member 2, and the elastic member 3 has a ring shape divided at one point in the circumferential direction, so that one or more conductive members 4 can be arranged over a wide circumferential direction along the recess 2a and easily fixed by the radial elastic restoring force of one elastic member 3.

[0065] In addition, this electric motor 10 comprises this current-carrying unit 1, a shaft 12, a housing 11 surrounding the shaft 12, and rolling bearings 15, 16 supporting the shaft 12 relative to the housing 11, and a conductive annular member 2 is fitted into the housing 11 as one of the components of the shaft 12 and the housing 11, and a tip portion 4b of the conductive member 4 is in contact with the shaft 12 as the other component, thereby electrically connecting the shaft 12 and the housing 11 with the simple current-carrying unit 1 and preventing electrical corrosion of the rolling bearings 15, 16 and radio noise.

[0066] In the first embodiment, the conductive annular member 2 is fixed to one of the members (the housing 11) by press-fitting it into the housing 11 as one of the members, but in this case, it is difficult to remove the conductive annular member 2 from the one of the members (the housing 11) when replacing the current-carrying unit 1. In order to improve the replaceability of the current-carrying unit 1, it is also possible to change the fixing structure of the conductive annular member 2.

[0067] For example, in this current-carrying unit 1, the outer periphery of the conductive ring-shaped member 2 shown in FIG. 1 may be changed to a male threaded portion, and the opening at one axial end of the housing 11 may be changed to a female threaded portion corresponding to the male threaded portion. Note that illustration of the male threaded portion and the female threaded portion is omitted. In this way, the conductive ring-shaped member 2 is fixed by screwing into the housing 11 as one of the members, so that the screwing between the housing 11 as one of the members and the conductive ring-shaped member 2 can be released, and the conductive ring-shaped member 2 can be removed from the housing 11 as one of the members. This improves the replaceability of the current-carrying unit 1.

[0068] In addition, the interchangeability of the current-carrying unit may be improved by fastening one of the shaft and the housing to the conductive annular member in the axial direction with a screw member. As an example, a second embodiment is shown in Fig. 5. In the following, only the differences from the first embodiment will be described, and the same reference numerals will be used for corresponding components.

[0069] The conductive annular member 2 according to the second embodiment has a flange portion 2c on the outer periphery of the conductive annular member 2. The housing 11 as one of the members has a step portion 11a that faces the flange portion 2c of the conductive annular member 2 in the axial direction. The step portion 11a of the housing 11 is located in a position that faces an opening on one axial end side of the housing 11 in the axial direction. The flange portion 2c of the conductive annular member 2 and the step portion 11a of the housing 11 are fastened in the axial direction by one or more screw members 5. The housing 11 and the conductive annular member 2 are not fixed in the axial direction by fitting the housing 11 and the conductive annular member 2 together, but are fixed solely by fastening the screw members 5.

[0070] In this way, in the current-carrying unit according to the second embodiment, the recess 2a of the conductive annular member 2 is formed on the inner circumference of the conductive annular member 2, and the conductive annular member 2 has a flange portion 2c on the outer circumference of the conductive annular member 2, so that when the conductive annular member 2 is fitted into the housing 11 and the current-carrying unit is assembled so that the conductive member 4 is in contact with the shaft 12, the flange portion 2c of the conductive annular member 2 can be axially locked by the housing 11. This makes it possible to appropriately determine the axial position of the conductive annular member 2 so that the rolling bearing 15 and the conductive annular member 2 do not butt against each other in the axial direction.

[0071] Furthermore, the electric motor according to the second embodiment includes the screw member 5 that fastens the conductive annular member 2 and the housing 11, which serves as one of the members, in the axial direction, so that the conductive annular member 2 can be axially removed from the housing 11, which serves as one of the members, by removing the screw member 5. This improves the replaceability of the current-carrying unit.

[0072] A third embodiment as another example is shown in Fig. 6. Note that the third embodiment is a further modification of the second embodiment, so only the differences from the second embodiment will be described here.

[0073] In the electric motor according to the third embodiment, instead of fastening the flange portion 2c of the conductive annular member 2 and the step portion 11a of the housing 11 with a screw member, one or more spring members 6 are sandwiched between the conductive annular member 2 and the bracket 17 in the axial direction. The flange portion 2c of the conductive annular member 2 is locked in the axial direction by the step portion 11a of the housing 11 against the elastic restoring force of the spring member 6. The housing 11 and the conductive annular member 2 are not fixed in the axial direction by fitting the housing 11 and the conductive annular member 2 together, but are fixed solely by the elastic restoring force of the spring member 6 between the bracket 17 and the conductive annular member 2 and the locking of the flange portion 2c and the step portion 11a.

[0074] As described above, the electric motor according to the third embodiment includes a bracket 17 joined to one end side of the housing 11 and a spring member sandwiched axially between the conductive annular member 2 and the bracket 17, the conductive annular member 2 is fitted into the housing 11, and the housing 11 has a step portion 11a that axially engages the flange portion 2c of the conductive annular member 2 against the elastic restoring force of the spring member 6, so that the conductive annular member 2 fitted into the housing 11 can be fixed by the bracket 17, the spring member 6, the flange portion 2c, and the step portion 11a of the housing 11, and the bracket 17 can be removed from the housing 11 to pull out the conductive annular member 2 in the axial direction from the housing 11. This improves the replaceability of the current-carrying unit.

[0075] In the third embodiment, the flange portion 2c is seamlessly formed as a part of the conductive annular member 2, but it is also possible to provide the flange portion by attaching a separate member to the conductive annular member. As an example of such an embodiment, a fourth embodiment is shown in Fig. 7. Note that the fourth embodiment is a further modification of the third embodiment, so only the differences from the third embodiment will be described here.

[0076] The electric motor according to the fourth embodiment has a conductive annular member 2 in which a retaining ring groove 2d is formed, and a retaining ring 7 is fitted into the retaining ring groove 2d as a flange portion. In this case, the number of parts is relatively large, but the replaceability of the current-carrying unit is still good.

[0077] In each embodiment such as the first embodiment described above, as shown in FIG. 8, the groove bottom surface of the recess 2a of the conductive annular member 2 is a surface along the axial direction, and the conductive member 4 is sandwiched straight in the radial direction between the groove bottom surface of the recess 2a and the elastic member 3. However, depending on manufacturing errors, a small gap g in the axial direction may occur between the elastic member 3 and the conductive member 4. During use of the current-carrying unit, the elastic member 3 may move freely in the axial direction depending on the size of the gap g. This movement may cause wear of the conductive member 4. To prevent this, it is possible to suppress the movement of the elastic member 3 by changing the cross-sectional shape of the recess 2a or the elastic member 3. As an example, a fifth embodiment is shown in FIG. 9.

[0078] The recess 2a of the conductive annular member 2 according to the fifth embodiment has a pair of inclined surfaces 2e symmetrical with respect to the axial direction. The recess 2a is formed as a groove with a V-shaped cross section. On the other hand, the elastic member 3 has an outer peripheral surface 3a with an arc-shaped cross section. The surface areas of the conductive annular member 2 and the elastic member 3, which sandwich the base end 4a of the conductive member 4 in the radial direction, are composed of a pair of inclined surfaces 2e of the recess 2a and the outer peripheral surface 3a of the elastic member 3, both of which are inclined with respect to the radial direction. Therefore, the elastic restoring force in the radial direction of the elastic member 3 is always received by the above-mentioned surface areas such as the inclined surfaces 2e, and a reaction force against the axial component of the elastic restoring force according to the inclination of the surface area is applied to the elastic member 3. This ensures a portion where the recess 2a and the elastic member 3 sandwich the base end 4a of the conductive member 4 without any gaps in the radial and axial directions, thereby suppressing the axial play of the elastic member 3.

[0079] For example, even if a pair of inclined surfaces 2e of the recess 2a is provided and the elastic member 3 is as shown in FIG. 8, or if the cross-sectional shape of the recess 2a is as shown in FIG. 8 and the outer peripheral surface 3a of the elastic member 3 is provided wider than the groove width of the recess 2a as shown in FIG. 9, it is possible to secure a portion where the recess 2a and the elastic member 3 sandwich the base end 4a of the conductive member 4 without any gap in the radial and axial directions, and to suppress the axial play of the elastic member 3, but the corners of the outer peripheral surface of the elastic member 3 are received by the pair of inclined surfaces 2e, or the groove edge corners of the recess 2a are received by the outer peripheral surface of the elastic member 3. From the viewpoint of preventing wear of the conductive member 4, it is preferable to prevent the conductive member 4 from being sandwiched in the radial and axial directions by providing a corresponding inclination to both the elastic member 3 and the above-mentioned surface regions of the recess 2a as shown in FIG. 9.

[0080] In this way, in the conductive unit of the fifth embodiment, the inclined surface 2e and the outer peripheral surface 3a as at least one of the surface areas of the recess 2a of the conductive annular member 2 that radially sandwiches the base end 4a of the conductive member 4 and the surface area of ​​the elastic member 3 are inclined relative to the radial direction, and the inclination of the inclined surface 2e and the outer peripheral surface 3a as at least one of the surface areas can suppress the axial movement of the elastic member 3.

[0081] In each of the above-described embodiments, the recess 2a of the conductive annular member 2 is continuous around the entire circumference, but a part of the recess 2a may be cut out to the extent that it does not affect the fixing of the conductive member 4, and this can be used to improve the ease of assembly of the current-carrying unit. As an example, a state in the middle of assembly of the sixth embodiment is shown in Fig. 10. Note that here, only the differences from the first embodiment will be described.

[0082] In the conductive annular member 2 according to the sixth embodiment, a hole 2f is formed so as to penetrate radially between the inner and outer periphery of the conductive annular member 2 and intersect with the recess 2a.

[0083] The conductive annular member 2 has cylindrical surfaces 2b on both sides of the recess 2a that extend in the axial and circumferential directions at positions adjacent to the recess 2a, and also has a step portion 2g that protrudes radially from the cylindrical surfaces 2b.

[0084] When assembling the current-carrying unit according to the sixth embodiment, the conductive member 4 can be set at an appropriate radial position on the cylindrical surface 2b of the conductive ring-shaped member 2, and the conductive member 4 can be set at an appropriate axial position on the step portion 2g of the conductive ring-shaped member 2. The state in which the conductive member 4 is set at an appropriate position relative to the recess 2a of the conductive ring-shaped member 2 can be maintained by sucking the air in the recess 2a through the hole 2f to adsorb the conductive member 4 to the cylindrical surface 2b. In this maintained state, the elastic member 3 can be fitted into the recess 2a of the conductive ring-shaped member 2. This makes it easy to appropriately sandwich the conductive member 4 between the recess 2a of the conductive ring-shaped member 2 and the elastic member 3.

[0085] In this way, the current-carrying unit according to the sixth embodiment has the hole 2f formed therein, which penetrates between the inner and outer periphery of the conductive annular member 2 and intersects with the recess 2a, and therefore the air inside the recess 2a of the conductive annular member 2 can be sucked through the hole 2f. Therefore, when assembling the current-carrying unit, the conductive member 4, which has been placed in advance at a predetermined position relative to the conductive annular member 2, can be temporarily attached to the predetermined position by being attracted to the conductive annular member 2 by the above-mentioned suction, and thus it becomes easy to appropriately sandwich the conductive member 4 between the recess 2a of the conductive annular member 2 and the elastic member 3.

[0086] In addition, the conductive unit of the sixth embodiment has a cylindrical surface 2b along the axial and circumferential directions at a position adjacent to the recess 2a of the conductive ring-shaped member 2, and a step portion 2g protruding radially from the cylindrical surface 2b. Therefore, when assembling the conductive unit, the conductive member 4 can be set at an appropriate radial position by the cylindrical surface 2b of the conductive ring-shaped member 2, and the conductive member 4 can be set at an appropriate axial position by the step portion 2g of the conductive ring-shaped member 2, which in turn makes it easier to properly clamp the conductive member 4 between the recess 2a of the conductive ring-shaped member 2 and the elastic member 3.

[0087] Although the sixth embodiment is a modification of the first embodiment, the holes 2f and the stepped portions 2g of the sixth embodiment can be used in the second to fifth embodiments.

[0088] In the sixth embodiment, the conductive member 4 can be maintained in a predetermined position by suctioning air through the hole 2f, but other position maintaining means can also be adopted. As an example, a state in the middle of assembly of the seventh embodiment is shown in Fig. 11. Note that here, only the differences from the first embodiment will be described.

[0089] In the current-carrying unit according to the seventh embodiment, the conductive member 4 is temporarily attached to the cylindrical surface 2b of the conductive ring-shaped member 2 by the adhesive material 8 before the elastic member 3 is fitted into the recess 2a of the conductive ring-shaped member 2. The adhesive material 8 is attached to a predetermined area of ​​the conductive member 4 before the conductive member 4 is arranged on the cylindrical surface 2b of the conductive ring-shaped member 2. The conductive member 4 may be arranged on the adhesive material 8 with the adhesive material 8 attached to the cylindrical surface 2b. In either case, the adhesive material 8 is arranged so as to be interposed between the conductive member 4 and the cylindrical surface 2b of the conductive ring-shaped member 2. The adhesive material 8 exerts an adhesive property that can maintain the conductive member 4 at a predetermined position with respect to the recess 2a until the elastic member 3 is fitted into the recess 2a, and can allow deformation (indicated by a dashed line in FIG. 11) that follows the recess 2a of the conductive member 4 as the elastic member 3 is fitted into the recess 2a. Examples of such adhesive materials 8 include grease and adhesive tape. In order to prevent the adhesive material 8 from impeding the conductivity between the conductive member 4 and the recess 2a, it is preferable to use an adhesive material 8 having conductivity, such as conductive grease. Note that it is also possible to temporarily attach the conductive member 4, which has been formed in advance into the shape shown in FIG. 2, to the conductive annular member 2 with the adhesive material 8. In this case, it is sufficient to place the adhesive material 8 having conductivity between the groove bottom surface of the recess 2a and the base end portion 4a of the conductive member 4.

[0090] In this way, the current-carrying unit of the seventh embodiment has an adhesive material 8 disposed between the conductive member 4 and the conductive ring-shaped member 2 in order to temporarily attach the conductive member 4 to the conductive ring-shaped member 2 before the elastic member 3 is fitted into the recess 2a of the conductive ring-shaped member 2. Therefore, when assembling the current-carrying unit, the conductive member 4 is temporarily attached at a predetermined position on the conductive ring-shaped member 2 with the adhesive material 8, and the elastic member 3 is fitted into and fixed in the recess 2a, thereby making it possible to create a current-carrying unit in which the base end 4a and tip end 4b of the conductive member 4 are appropriately provided, as shown in Figure 2.

[0091] In the seventh embodiment, an example has been shown in which an adhesive material is used instead of maintaining the position of the conductive member by suctioning air through the hole as in the sixth embodiment. However, it is also possible to combine the seventh embodiment with the sixth embodiment to use a combination of an adhesive material and air suction, and to use an adhesive material with weaker adhesive properties to make it easier for the conductive member to deform when fitted into the recess of the elastic member.

[0092] In each of the above-described embodiments, an example has been shown in which the recess 2a is formed on the inner circumference of the conductive annular member 2, but it is also possible to form the recess 2a on the outer circumference of the conductive annular member 2. An eighth embodiment as an example is shown in Fig. 12. Note that here, only the differences from the first embodiment will be described.

[0093] The conductive annular member 21 of the current-carrying unit 20 according to the eighth embodiment is fitted onto the shaft 12, which is one of the shaft 12 and the housing 11. The recess 21a of the conductive annular member 21 is formed on the outer periphery of the conductive annular member 21. The elastic member 22 serves as a retaining ring that radially fastens the conductive member 23 against the recess 21a. The conductive member 23 is in contact with the housing 11.

[0094] In the eighth embodiment, the configurations of the second to seventh embodiments can be combined in any manner as long as they can be used in combination.

[0095] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0096] 1, 20 Power supply unit 2, 21 Conductive ring member 2a, 21a Recess 2b Cylindrical surface 2c Flange part 2d Retaining ring groove 2e Slope 2f hole 2g stepped section 3, 22 Elastic member 3a Outer surface 4, 23 Conductive materials 4a Proximal end 4b Tip 5 Screw member 6 Spring members 7 Retaining ring 8 Adhesive material 10 Electric motor 11. Housing 11a Stepped section 12 Axis 15, 16 Rolling bearings 17 Bracket

Claims

1. a conductive annular member having a recess; An elastic member fitted in the recess; a conductive member having a base end portion sandwiched between the recess and the elastic member, and a tip end portion extending into a hollow space from the recess and the elastic member, A current-carrying unit in which the base end of the conductive member and the elastic member are fixed by the elastic restoring force of the elastic member.

2. 2. The energization unit according to claim 1, wherein the conductive member has a plurality of tip portions extending from both sides of the base end portion.

3. the recess of the conductive annular member is a groove extending in a circumferential direction on an inner or outer periphery of the conductive annular member, 2. The current-carrying unit according to claim 1, wherein the elastic member has an annular shape that is divided at one location in the circumferential direction.

4. The conductive unit according to claim 3 , wherein at least one of the surface areas of the recess of the conductive annular member and the surface area of ​​the elastic member, which radially sandwich the base end of the conductive member, is formed as a slope inclined relative to the radial direction.

5. 4. The current-carrying unit according to claim 3, wherein a hole is formed which penetrates between the inner and outer periphery of the conductive annular member and intersects with the recess.

6. The current-carrying unit according to claim 3 , wherein the conductive annular member has a cylindrical surface extending along the axial and circumferential directions at a position adjacent to the recess, and a step portion protruding radially from the cylindrical surface.

7. The current-carrying unit according to claim 3 , further comprising an adhesive material disposed between the conductive member and the conductive annular member.

8. the recess of the conductive annular member is formed on an inner circumference of the conductive annular member, The current-carrying unit according to claim 3 , wherein the conductive annular member has a flange portion on an outer periphery of the conductive annular member.

9. The current-carrying unit according to claim 1 , wherein the conductive member is made of conductive fiber.

10. 2. The current-carrying unit according to claim 1, wherein the conductive member is made of a conductive resin.

11. A current-carrying unit according to any one of claims 1 to 10, a shaft, a housing surrounding the shaft, and a rolling bearing supporting the shaft relative to the housing, an electric motor in which the conductive annular member is fitted to one of the shaft and the housing, and the tip of the conductive member is in contact with the other member.

12. 12. The electric motor according to claim 11, wherein the conductive annular member is secured to the one member by threaded engagement.

13. The electric motor according to claim 11 , further comprising a screw member that fastens the conductive annular member and the one member in the axial direction.

14. a bracket coupled to one end of the housing; and a spring member axially sandwiched between the conductive annular member and the bracket, The conductive annular member is fitted to the housing, 12. The electric motor according to claim 11, wherein the housing has a step portion that axially engages the flange portion of the conductive annular member against the elastic restoring force of the spring member.

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