Magnetic wedge, and rotating electric machine using a magnetic wedge

Abstract

To provide a magnetic wedge in which leakage magnetic flux penetrating in a circumferential direction is reduced.SOLUTION: A magnetic wedge which closes an opening of a slot, in which a coil exciting a stator core of a rotary electric machine is accommodated, comprises: a first high permeability part in contact with first teeth forming an inner wall of the slot at one side in a circumferential direction; a second high permeability part in contact with second teeth forming an inner wall of the slot at the other side in the circumferential direction; and a low permeability part which is provided between the first high permeability part and the second high permeability part in the circumferential direction and of which the permeability is lower than that of the first high permeability part and the second high permeability part. The first high permeability part and the second high permeability part include a high permeability agent, and the first high permeability part and the second permeability part are configured by coating a glass cloth with a synthetic resin containing the high permeability agent.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a magnetic wedge and a rotating electrical machine using the magnetic wedge.

Background Art

[0002] Conventionally, there is known a rotating electrical machine that excites a coil accommodated in a slot formed between adjacent teeth of a stator by energizing the coil, and rotates a rotor. In such a rotating electrical machine, a wedge may be inserted so as to close the opening of the slot between adjacent teeth to fix the coil and prevent it from falling off.

[0003] When a non-magnetic wedge is used as the wedge for closing the opening of the slot, magnetic flux concentrates on the tooth portion with respect to the slot portion. Therefore, the spatial distribution of the magnetic flux density in the air gap has unevenness in the circumferential direction. This unevenness of the magnetic flux density adds harmonics, which are integer multiples of the fundamental wave of the magnetic flux density in the air gap of the rotating electrical machine, causing a decrease in efficiency.

[0004] On the other hand, for example, Patent Document 1 discloses a technique for reducing losses due to harmonics by using a magnetic wedge as the wedge for closing the opening of the slot. When a magnetic wedge is used, magnetic flux flows through the magnetic wedge even in the slot portion, so the unevenness of the magnetic flux density is alleviated, and losses due to harmonics can be reduced.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, with conventional magnetic wedges, increasing the permeability of the wedge causes magnetic flux to flow in directions other than the desired one, for example, the magnetic flux may penetrate the magnetic wedge in the circumferential direction. In this case, leakage flux flows from one of the teeth on either side of the magnetic wedge through the magnetic wedge to the other tooth, and then from the other tooth to the rotor, and from the rotor to the first tooth, creating a circulation of leakage flux. An increase in this circulating leakage flux leads to an increase in current, which reduces the efficiency of the rotating electric machine.

[0007] The present invention aims to provide a magnetic wedge that reduces leakage magnetic flux penetrating in the circumferential direction. [Means for solving the problem]

[0008] A magnetic wedge according to one aspect of the present invention is a magnetic wedge for closing an opening in a slot that houses a coil for exciting the stator core of a rotating electric machine, comprising: a first high-permeability portion that contacts a first tooth forming the inner wall on one circumferential side of the slot; a second high-permeability portion that contacts a second tooth forming the inner wall on the other circumferential side of the slot; and a low-permeability portion provided between the first high-permeability portion and the second high-permeability portion in the circumferential direction, having a lower permeability than the first high-permeability portion and the second high-permeability portion. It is made by laminating sheet-like members in the radial direction, The first high-permeability portion and the second high-permeability portion contain a high-permeability agent, and the first high-permeability portion and the second high-permeability portion are characterized by being formed by coating a glass cloth with a synthetic resin containing the high-permeability agent.

[0009] In the magnetic wedge according to one embodiment described above, the highly permeable material is amorphous, permalloy, or silicon steel.

[0010] In the magnetic wedge according to one embodiment described above, the low permeability portion is characterized in that a synthetic resin that does not contain the high permeability agent is applied to the glass cloth.

[0011] A rotating electric machine according to one aspect of the present invention is characterized by having a stator having the magnetic wedge and the stator core, and a rotor disposed radially inward of the stator via an air gap. [Effects of the Invention]

[0012] According to one aspect of the present invention, a magnetic wedge with reduced leakage magnetic flux penetrating in the circumferential direction can be provided. [Brief explanation of the drawing]

[0013] [Figure 1] This is a partial cross-sectional view of a motor according to the first embodiment of the present invention. [Figure 2] This is a perspective view illustrating a magnetic wedge according to a first embodiment of the present invention. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described below with reference to the drawings. In the embodiments, for the sake of clarity, structures and elements other than the main parts of the present invention will be simplified or omitted in the description. Also, the same elements will be denoted by the same reference numerals in the drawings. Note that the shapes and dimensions of each element shown in the drawings are schematic representations and do not represent the actual shapes and dimensions.

[0015] <First Embodiment> Figure 1 is a partial cross-sectional view of a motor according to the first embodiment of the present invention. The motor 10 of the first embodiment is an example of a rotating electric machine. The motor 10 is an inner rotor type motor. The motor 10 has a stator 20 and a rotor 30. The stator 20 is arranged radially outward of the rotor 30 with an air gap between them. The rotor 30 is rotatable about the axis of rotation. Figure 1 is a view showing the motor 10 cut in a plane perpendicular to the axis of rotation.

[0016] Unless otherwise specified, the direction along the extension of the axis of rotation is simply called the "axial direction." The radial direction centered on the axis of rotation is simply called the "radial direction." In the radial direction, the side approaching the axis of rotation is called the "inner radial direction," and the side moving away from the axis of rotation is called the "outer radial direction." The circumferential direction centered on the axis of rotation, that is, around the axis of rotation, is simply called the "circumferential direction." In the circumferential direction, the counterclockwise side in Figure 1 is called the "one circumferential side," and the clockwise side in Figure 1 is called the "other circumferential side."

[0017] The stator 20 is cylindrical and coaxial with the axis of rotation. The stator 20 has a stator core 50. The stator core 50 has a core back 20a that encircles the radially outer side and teeth 20b that extend radially inward from the core back 20a. Multiple teeth 20b are arranged at equal intervals in the circumferential direction. A slot 21 is formed between one of the multiple teeth 20b and a tooth 20b that is circumferentially adjacent to that tooth 20b. The slot 21 opens radially inward. The stator 20 has a coil 22. The slot 21 accommodates the coil 22. The coil 22 is wound around the teeth 20b.

[0018] The rotor 30 is cylindrical and coaxial with the axis of rotation. The rotor 30 has a rotor core 60 in which permanent magnets (not shown) are embedded. The radially inner end of the teeth 20b faces the radially outer end of the rotor core 60, with an air gap between them.

[0019] The teeth 20b have grooves 23 that are recessed in the circumferential direction, located radially inward of the coil 22 housed in the slot 21. The stator 20 has wedges 25. The wedges 25 fit into the grooves 23 of adjacent teeth 20b, preventing the coil 22 housed in the slot 21 from falling out. The wedges 25 close the radially inward opening of the slot 21.

[0020] The wedge 25 has a low magnetic permeability portion 25a, a high magnetic permeability portion 25b, and a high magnetic permeability portion 25c. The wedge 25 is an example of a magnetic wedge. The high magnetic permeability portion 25b contacts one of the adjacent teeth 20b, and the high magnetic permeability portion 25c contacts the other of the adjacent teeth 20b. That is, the tooth 20b forming the inner wall on one side in the circumferential direction of the slot 21 contacts the high magnetic permeability portion 25b of the wedge 25, and the tooth 20b forming the inner wall on the other side in the circumferential direction of the slot 21 contacts the high magnetic permeability portion 25c of the wedge 25. The high magnetic permeability portion 25b is located on one side in the circumferential direction relative to the low magnetic permeability portion 25a. The high magnetic permeability portion 25c is located on the other side in the circumferential direction relative to the low magnetic permeability portion 25a. Note that the low magnetic permeability portion 25a only needs to inhibit the flow of magnetic flux between the high magnetic permeability portion 25b and the high magnetic permeability portion 25c, and not all of the low magnetic permeability portion 25a needs to have a low magnetic permeability.

[0021] In FIG. 1, the arrow A is an arrow indicating an example of the flow of magnetic flux. As shown by the arrow A, the magnetic flux flows from the tooth 20b through the high magnetic permeability portions 25b and 25c of the wedge 25 to the rotor core 60. Thus, according to this embodiment, unlike the case where the opening of the slot 21 is blocked by a non-magnetic wedge, the magnetic flux can flow even if the circumferential position is the opening position of the slot 21. Therefore, the coarseness and fineness of the magnetic flux density in the circumferential direction are alleviated, and the loss due to harmonics can be reduced.

[0022] FIG. 2 is a diagram for explaining the wedge 25. FIG. 2(A) shows the plate-like member 50 serving as the base of the wedge 25. FIG. 2(B) shows the wedge 25 obtained by machining the plate-like member 50.

[0023] First, a method for manufacturing the plate-like member 50 will be described. As shown in Fig. 2(A), the plate-like member 50 is formed by laminating a plurality of sheet-like members 50c. In each of the plurality of sheet-like members 50c, high magnetic permeability portions 50a and low magnetic permeability portions 50b are alternately arranged in a stripe pattern. The sheet-like member 50c includes a non-magnetic sheet-like glass cloth. A synthetic resin containing a high magnetic permeability agent is applied to the portion of the high magnetic permeability portion 50a on this glass cloth, and a non-magnetic synthetic resin not containing a high magnetic permeability agent is applied to the portion of the low magnetic permeability portion 50b, thereby forming it. The synthetic resin serves as an adhesive, and by laminating a plurality of sheet-like members 50c and applying pressure or heat as necessary, the sheet-like members 50c are adhered to each other. At this time, the synthetic resin impregnates the glass cloth. When the entire surface of the glass cloth is adhered with the synthetic resin, the strength can be improved. The wedge 25 can improve the strength by laminating the glass cloth.

[0024] The wedge 25 is obtained by cutting the plate-like member 50 obtained by adhering the sheet-like members 50c to each other into a desired shape. The wedge 25 is cut into a shape that closes the opening of the slot 21 and fits into the groove portion 23 of the teeth 20b. In the present embodiment, the high magnetic permeability portion 50a of the plate-like member 50 becomes the high magnetic permeability portion 25b of the wedge 25, the low magnetic permeability portion 50b of the plate-like member 50 becomes the low magnetic permeability portion 25a of the wedge 25, and the high magnetic permeability portion 50a of the plate-like member 50 becomes the high magnetic permeability portion 25c of the wedge 25, and the wedge 25 is cut out from the plate-like member 50.

[0025] As the high magnetic permeability agent for the high magnetic permeability portion 50a, amorphous, permalloy, silicon steel, etc. can be used. Iron powder can also be used as the high magnetic permeability agent. However, when iron powder is mixed with the synthetic resin as the high magnetic permeability agent, if the iron powder content is increased to increase the magnetic permeability, the strength as a wedge will decrease. On the other hand, if amorphous, permalloy, silicon steel, etc. are used as the high magnetic permeability agent, the magnetic permeability can be improved without increasing the metal powder content, that is, without reducing the strength.

[0026] In this embodiment, the wedge 25 has a low-permeability section 25a between the high-permeability section 25b and the high-permeability section 25c in the circumferential direction between adjacent teeth 20b. Therefore, magnetic flux is less likely to penetrate the wedge 25 in the circumferential direction, reducing leakage flux and preventing a decrease in the efficiency of the motor 10.

[0027] In the above example, a non-magnetic synthetic resin that does not contain a high-permeability agent is applied to the low-permeability portion 50b. However, the present invention is not limited to this, and nothing may be applied to the low-permeability portion 50b, and only glass cloth may be used.

[0028] Furthermore, the dimensional ratio of the high-permeability section 25b, the low-permeability section 25a, and the high-permeability section 25c in the circumferential direction of the wedge 25 can be determined according to the performance required of the motor 10. For example, by making the circumferential lengths of the high-permeability section 25b and the high-permeability section 25c longer than those of the low-permeability section 25a, the unevenness of magnetic flux density in the circumferential direction can be further mitigated. Alternatively, by making the circumferential lengths of the high-permeability section 25b and the high-permeability section 25c shorter than those of the low-permeability section 25a, the unevenness of magnetic flux density in the circumferential direction can be further mitigated.

[0029] The plate-shaped member 50 may also be formed by applying a non-magnetic synthetic resin to the entire surface of a glass cloth, and then applying a synthetic resin containing a high magnetic permeability agent only to the high magnetic permeability portion 50a.

[0030] According to this embodiment, by forming the plate-shaped member 50 as described above and then manufacturing the wedge 25 by cutting, the manufacturing process can be simplified and manufacturing costs reduced compared to the case where the low-permeability portion 25a, high-permeability portion 25b, and high-permeability portion 25c are formed from the shape and size of the wedge 25 from the beginning.

[0031] The present invention is not limited to the embodiments described above, and various improvements and design modifications may be made without departing from the spirit of the invention. The present invention also includes combinations of each embodiment. In addition, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0032] 10...Motor, 20...Stator, 30...Rotor, 25...Wedge

Claims

1. A magnetic wedge that closes the opening of a slot housing a coil for exciting the stator core of a rotating electric machine, A first high-permeability portion that contacts the first teeth forming the inner wall on one side in the circumferential direction of the slot, A second high-permeability portion that contacts the second teeth forming the inner wall on the other side in the circumferential direction of the aforementioned slot, A low-permeability portion is provided in the circumferential direction between the first high-permeability portion and the second high-permeability portion, and has a lower permeability than the first high-permeability portion and the second high-permeability portion. It is formed by laminating sheet-like members having the following properties in the radial direction: The first high-permeability portion and the second high-permeability portion contain a high-permeability agent. The first high-permeability portion and the second high-permeability portion are formed by coating a glass cloth with a synthetic resin containing the high-permeability agent. A magnetic wedge characterized by the following.

2. The aforementioned highly magnetic permeable material is amorphous, permalloy, or silicon steel. The magnetic wedge according to feature 1.

3. The low-permeability portion is formed by coating the glass cloth with a synthetic resin that does not contain the high-permeability agent. The magnetic wedge according to feature 1.

4. A stator having the magnetic wedge and the stator core as described in claim 1, A rotor is positioned radially inward of the stator via an air gap, Having, A rotating electric machine characterized by the following features.

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