Slip ring assembly and rotating electrical machine

Abstract

To provide a slip ring assembly in which a product having a changed adjustment amount of a dynamic balance can be relatively easily produced while the production cost is suppressed.SOLUTION: A slip ring assembly that is mounted on a shaft of a rotary electric machine, includes three-phase slip rings that are disposed concentrically on the outer circumferential side of the shaft and are arranged in the axis direction, three-phase lead bars that are respectively connected to the slip rings and extend in the axis direction of the shaft at different positions in the circumferential direction, a cylindrical core material that is disposed concentrically on the inner circumferential side of the slip rings and is fitted to the shaft, and a resin mold part. The lead bars have different axial lengths according to the positions of the corresponding connected slip rings in the axis direction. The core material has a cut portion in a position corresponding to a resultant vector of centrifugal forces acting on the lead bars in the circumferential direction.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a slip ring assembly and a rotating electrical machine.

Background Art

[0002] Conventionally, a rotating electrical machine is known in which a slip ring is attached to a shaft and power is supplied to a coil of a rotor via the slip ring. In a three-phase AC slip ring, if the lengths of bus bars extending in the axial direction are different for each phase, the circumferential mass becomes uneven, and the dynamic balance of the slip ring and the rotor increases.

[0003] For example, Patent Document 1 discloses a slip ring in which a bus bar having a shorter axial length has a larger cross-sectional area in a cross-section perpendicular to the rotation axis, and the dynamic balance is improved by the difference in the thickness of the bus bars of each phase. Further, for example, Patent Document 2 discloses a configuration in which a neutral point connection portion is provided at a position on the opposite side around the rotation axis X with respect to the resultant vector Y of the centrifugal forces of the bus bars, and a vector Z of the centrifugal force in the direction opposite to the resultant vector Y is generated to achieve balance.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the manufacture of a slip ring, from the viewpoint of suppressing material costs, it is preferable that the three-phase lead bars have the same cross-sectional shape. Further, adding components and shapes for adjusting the dynamic balance is not preferable because it makes the resin injection mold complicated.

[0006] The present invention has been made in view of the above circumstances, and provides a slip ring assembly that can relatively easily manufacture a product with a changed dynamic balance adjustment amount while suppressing manufacturing costs.

Means for Solving the Problems

[0007] One aspect of the present invention is a slip ring assembly attached to the shaft of a rotating electrical machine. The slip ring assembly includes three-phase slip rings concentrically arranged on the outer peripheral side of the shaft and arranged along the axial direction, three-phase lead bars respectively connected to the slip rings and extending in the axial direction of the shaft at different circumferential positions, a cylindrical core material concentrically arranged on the inner peripheral side of the slip ring and fitted to the shaft, and a resin molding portion insert-molded into the slip ring, the lead bar, and the core material. The lead bars have different axial lengths corresponding to the axial positions of the connected slip rings, and the core material has a notch at a position corresponding to the resultant vector of the centrifugal forces acting on the lead bars in the circumferential direction.

[0008] The notch of the core material may be arranged between a first lead bar having the longest axial length and a second lead bar having the second-longest axial length in the circumferential direction. The size of the notch may be calculated by multiplying the resultant mass corresponding to the centrifugal resultant force of the lead bars by the ratio of the centroid radius of the lead bar to the centroid radius of the notch and the reciprocal of the difference between the specific gravity of the core material and the specific gravity of the resin of the resin molding portion. Another aspect of the rotating electrical machine of the present invention includes the above-described slip ring assembly, a rotor in which the slip ring assembly is fitted to the shaft, and a stator.

Effects of the Invention

[0009] The slip ring assembly according to one aspect of the present invention can relatively easily manufacture a product with a changed dynamic balance adjustment amount while suppressing manufacturing costs.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiments, for the sake of easy understanding of the description, structures and elements other than the main part of the present invention will be described in a simplified or omitted manner. Also, in the drawings, the same reference numerals are given to the same elements. Note that the shapes, dimensions, etc. of each element shown in the drawings are schematically shown and do not represent actual shapes, dimensions, etc.

[0012] In the drawings, the rotating shaft of the rotating electrical machine is indicated by the reference numeral AX as necessary. Also, in the following description, the circumferential direction centered on the rotating shaft AX is simply referred to as the circumferential direction, and the radial direction centered on the rotating shaft AX is simply referred to as the radial direction.

[0013] FIG. 1 is a figure showing a configuration example of a rotating electrical machine according to this embodiment. The rotating electrical machine 10 according to this embodiment is an inner rotor type motor, and includes a rotor 11, a stator 12, a shaft 13, a first casing 14 and a second casing 15, bearings 16, a brush holder 17, and a slip ring assembly 20.

[0014] The rotor 11 has a plurality of coils 11a wound around it such that magnetic poles are formed at equal intervals along the circumferential direction. Further, at the center of the rotor 11, a shaft 13 is fitted so as to penetrate the iron core of the rotor 11 along the rotation axis AX.

[0015] The stator 12 is arranged concentrically with the rotor 11 with a slight air gap therebetween on the outer periphery of the rotor 11. In the stator 12, magnetic poles are formed at equal intervals by coils or magnets along the circumferential direction. In the rotating electrical machine 10, by sequentially switching the magnetic field of the rotor 11 by controlling the current of the coils 11a of the rotor 11, an attractive force or a repulsive force with the magnetic field of the stator 12 is generated. As a result, the rotor 11 rotates about the rotation axis AX, and the rotating electrical machine 10 is driven.

[0016] The first casing 14 is a housing that houses the rotor 11 and the stator 12, and rotatably supports the shaft 13 via bearings 16, 16. The load side (one side) of the shaft 13 penetrates the first casing 14 and is exposed to the outside. Further, the non-load side (the other side) of the shaft 13 extends into a second casing 15 connected to the first casing 14. Further, on the non-load side of the shaft 13, a slip ring assembly 20 that supplies power to the coils 11a of the rotor 11 is attached.

[0017] The second casing 15 houses a brush holder 17 and the slip ring assembly 20. The slip ring assembly 20 has three slip rings 21K, 21L, 21M respectively corresponding to the respective phases of a three-phase alternating current (hereinafter also referred to as the K phase, the L phase, and the M phase) arranged at predetermined intervals in the axial direction. The brush holder 17 holds three sets of power supply brushes 17a that are electrically in contact with the slip rings 21K, 21L, 21M at intervals in the axial direction, and supplies power to the slip rings 21K, 21L, 21M of each phase via the power supply brushes 17a.

[0018] Next, a configuration example of the slip ring assembly 20 of the present embodiment will be described. FIG. 2 is a perspective view of an example of the slip ring assembly 20. FIG. 3 is a plan view of the slip ring assembly. FIG. 4 is a view showing a cross section taken along line IV-IV of FIG. 3. FIG. 5 is a view showing the slip rings and lead bars of each phase. FIG. 6 is a perspective view showing a state in which the resin molding portion of the slip ring assembly is removed.

[0019] The slip ring assembly 20 includes three slip rings 21K, 21L, 21M, three lead bars 22K, 22L, 22M, a core material (ring core) 23, and a resin molding portion 24.

[0020] The slip rings 21K, 21L, 21M and the lead bars 22K, 22L, 22M are each formed of a conductive metal and are provided corresponding to each phase of a three-phase alternating current. The slip ring 21K and the lead bar 22K correspond to the K phase, the slip ring 21L and the lead bar 22L correspond to the L phase, and the slip ring 21M and the lead bar 22M correspond to the M phase.

[0021] The slip rings 21K, 21L, 21M are all annular in the same shape. The slip rings 21K, 21L, 21M are arranged concentrically with respect to the rotation axis AX and the shaft 13, and the outer peripheral surface is exposed outside the resin molding portion 24. In the slip ring assembly 20, the slip rings 21K, 21L, 21M are arranged at predetermined intervals in the axial direction in order from the other side.

[0022] One end of each of the lead bars 22K, 22L, 22M is connected to the corresponding slip rings 21K, 21L, 21M, respectively. Further, the lead bars 22K, 22L, 22M extend to the other side along the axial direction at a position inside the radial direction of the slip rings 21K, 21L, 21M and are disposed up to the other side of the slip ring assembly 20. In addition, receiving seats 25 for connecting wiring members (not shown) to the coil 11a inserted into the shaft 13 are formed at the other ends of the respective lead bars 22K, 22L, 22M.

[0023] The lead bars 22K, 22L, and 22M are arranged at equal intervals in the circumferential direction, and the L-phase and M-phase are arranged clockwise from the K-phase. Also, the axial lengths of the lead bars 22K, 22L, and 22M differ according to the axial positions of the slip rings 21K, 21L, and 21M of each phase. The axial length of the lead bar 22K of the K-phase where the slip ring 21K is arranged on the other side is the shortest, and the axial lengths increase in the order of the lead bar 22L of the L-phase and the lead bar 22M of the M-phase. Therefore, the masses of the respective lead bars are different. Note that the lead bar 22M of the M-phase is an example of the first lead bar, and the lead bar 22L of the L-phase is an example of the second lead bar.

[0024] The core material 23 is a cylindrical body made of metal and is a member that fits with the end portion on the anti-load side of the shaft 13. The core material 23 is arranged concentrically with the inner circumferences of the slip rings 21K, 21L, and 21M along the rotation axis AX and is embedded inside the resin molding portion 24. Also, the core material 23 has a notch portion 26 in a part of the circumferential direction in order to achieve dynamic balance with the mass difference of the lead bars 22K, 22L, and 22M in the circumferential direction. The notch portion 26 extends in the axial direction of the core material 23 and has a shape in which a part of the outer circumference of the core material 23 is cut out by a plane orthogonal to the radial direction. The size of the notch portion 26 and the positional relationship between the notch portion 26 and the lead bars 22K, 22L, and 22M will be described later.

[0025] The resin molding portion 24 has an overall cylindrical shape and is formed by injection molding an insulating resin material. The slip ring assembly 20 is an insert molded body in which the gaps between the slip rings 21K, 21L, 21M, the lead bars 22K, 22L, 22M, and the core material 23 are filled by the resin molding portion 24, and the resin molding portion 24 has the function of integrating these elements while insulating them.

[0026] Hereinafter, the adjustment of the dynamic balance of the slip ring assembly 20 by the notch portion 26 of the core material 23 will be described. As described above, due to the mass difference caused by the difference in the axial lengths of the lead bars 22K, 22L, and 22M, the centrifugal forces acting on each of the lead bars 22K, 22L, and 22M become unbalanced. On the other hand, in the circumferential direction of the slip ring assembly 20, the position of the notch 26 of the core material 23 has a lower mass partially, and the centrifugal force acting on the core material 23 becomes unbalanced in the circumferential direction. Therefore, in the present embodiment, the dynamic balance during the rotation of the slip ring assembly 20 is adjusted by balancing the centrifugal force acting on each of the lead bars 22K, 22L, and 22M and the centrifugal force acting on the core material 23.

[0027] The circumferential position of the notch 26 of the core material 23 is determined by the resultant centrifugal force acting on each of the lead bars 22K, 22L, and 22M. As shown in FIG. 7, the circumferential position of the notch 26 can be obtained from the resultant vector F of the vector M of the centrifugal force acting on the lead bar 22M, the vector L of the centrifugal force acting on the lead bar 22L, and the vector K of the centrifugal force acting on the lead bar 22K. Specifically, the notch 26 of the core material 23 is positioned such that the center of the notch 26 coincides with the position of the resultant vector F.

[0028] Normally, the notch 26 is positioned between the lead bar 22M having the longest axial length and the lead bar 22L having the second longest axial length. In the case of the present embodiment, as shown in FIG. 3, the center of the notch 26 of the core material 23 is located at a position shifted 30° counterclockwise with respect to the center of the lead bar 22M.

[0029] Also, the size of the notch 26 of the core material 23 can be determined by the following method. Here, let the combined mass corresponding to the centrifugal resultant force of the lead bar be m, the angular velocity of the slip ring assembly be ω, the radius of the center of gravity of the lead bar be R1, the volume of the notch be V, the radius of the center of gravity of the notch be R2, and the specific gravity of the core material be ρ S , and the specific gravity of the resin of the resin molding part be ρ M . At this time, from the relationship of the following formula (1), the volume V of the notch can be obtained by the following formula (2). mR1ω 2 +Vρ M R2ω2 =Vρ S R2ω 2 …(1) V = m(R1 / R2) / (ρ S -ρ M ) …(2)

[0030] That is, according to Equation (2), for the combined mass m corresponding to the centrifugal resultant force of the lead bar, the ratio (R1 / R2) of the radius R1 of the center of gravity of the lead bar to the radius R2 of the center of gravity of the notch, and the specific gravity ρ of the core material S and the specific gravity ρ of the resin of the resin molding part M of the difference (ρ S -ρ M ), it can be seen that the volume V of the notch can be calculated by multiplying by the reciprocal. Then, the outer circumference of the core material 23 may be partially cut out so as to be equal to the volume V of the notch obtained by Equation (2) to form the notch 26.

[0031] Hereinafter, the effects of the slip ring assembly of the present embodiment will be described. The slip ring assembly 20 of the present embodiment is concentrically arranged on the outer peripheral side of the shaft 13, and includes three-phase slip rings 21K, 21L, 21M arranged along the axial direction, three-phase lead bars 22K, 22L, 22M respectively connected to the slip rings 21K, 21L, 21M and extending in the axial direction of the shaft 13 at different circumferential positions, a cylindrical core material 23 concentrically arranged on the inner peripheral side of the slip rings 21K, 21L, 21M and fitted with the shaft 13, and a resin molding part 24 insert-molded into the slip rings 21K, 21L, 21M, the lead bars 22K, 22L, 22M, and the core material 23. The lead bars 22K, 22L, 22M have different axial lengths corresponding to the axial positions of the connected slip rings 21K, 21L, 21M, and the core material 23 has a notch 26 at a position corresponding to the resultant vector of the centrifugal forces acting on the lead bars 22K, 22L, 22M in the circumferential direction.

[0032] According to this embodiment, a notch 26 of the core material 23 is formed at a position corresponding to the resultant vector of the centrifugal forces acting on the lead bars 22K, 22L, and 22M, and the balance between the centrifugal forces acting on each of the lead bars 22K, 22L, and 22M and the centrifugal force acting on the core material 23 is achieved, so that the dynamic balance during rotation can be adjusted. In addition, the formation of the notch 26 only requires simple processing on the outer periphery of the core material 23 that is insert-molded, and the circumferential positioning of the notch 26 is also relatively easy. Therefore, according to this embodiment, it is possible to easily adjust the dynamic balance by simply adding simple processing to a part of the core material 23. In addition, the cross-sectional shapes of the three-phase lead bars can be made the same, and no additional parts or shapes are required for adjusting the dynamic balance, so the resin injection mold does not need to be complicated. Therefore, this embodiment is also advantageous in that the manufacturing cost can be suppressed.

[0033] The present invention is not limited to the above embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention. For example, in the above embodiment, an example in which the slip ring assembly is attached to the motor has been described, but the slip ring assembly of the present invention can also be applied to a generator.

[0034] In addition, the embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of claims rather than the above description, and it is intended that all changes within the meaning and scope equivalent to the scope of claims are included.

Explanation of Reference Numerals

[0035] 10... rotating electrical machine, 11... rotor, 11a... coil, 12... stator, 13... shaft, 14... first casing, 15... second casing, 16... bearing, 17... brush holder, 17a... power supply brush, 20... slip ring assembly, 21K, 21L, 21M... slip rings, 22K, 22L, 22M... lead bars, 23... core material, 24... resin molded part, 25... receiving seat, 26... notch

Claims

1. A slip ring assembly attached to the shaft of a rotating electrical machine, comprising: Three-phase slip rings concentrically arranged on the outer peripheral side of the shaft and arranged along the axial direction; Three-phase lead bars respectively connected to the slip rings and extending in the axial direction of the shaft at different circumferential positions; A cylindrical core member concentrically arranged on the inner peripheral side of the slip ring and fitted to the shaft; A resin molding portion insert-molded into the slip ring, the lead bar, and the core member; The axial lengths of the lead bars are different corresponding to the axial positions of the slip rings to which they are connected; The core member has a notch at a position corresponding to the resultant vector of the centrifugal forces acting on the lead bar in the circumferential direction; A slip ring assembly.

2. The notch of the core member is arranged in the circumferential direction between a first lead bar having the longest axial length and a second lead bar having the second-longest axial length; The slip ring assembly according to Claim 1.

3. The size of the notch is calculated by multiplying the combined mass corresponding to the centrifugal resultant force of the lead bar by the ratio of the centroid radius of the lead bar to the centroid radius of the notch and the reciprocal of the difference between the specific gravity of the core member and the specific gravity of the resin of the resin molding portion; The slip ring assembly according to Claim 1 or Claim 2.

4. The slip ring assembly according to Claim 1; A rotor having the slip ring assembly fitted to a shaft; A stator; A rotating electrical machine comprising the above components.

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