Rotating electrical machine

Abstract

To provide a rotating electric machine capable of reducing iron loss due to gaps formed between a plurality of concave portions of a back yoke and one ends of a plurality of teeth fitted to the plurality of concave portions of the back yoke.SOLUTION: A rotating electric machine 1000 includes a rotor 200, a stator 100 surrounding the outer circumference of the rotor 200, a first recess 133 provided in the inner peripheral surface of a back yoke 130 of a stator 100 and extending in the axial direction of the stator 100, and a teeth 120 one end of which is fitted in the first recess 133, and a gap formed between first recess 133 and one end of tooth 120 fitted in first recess 133 is smaller in the circumferential direction of stator 100 than in the radial direction of the stator 100.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a rotating electrical machine.

Background Art

[0002] In order to reduce iron loss, rotating electrical machines using soft magnetic materials such as iron-based amorphous alloys (hereinafter referred to as amorphous metals) and nanocrystalline materials for the iron core have been developed. However, the steel sheet of the soft magnetic material has a very thin thickness and a Vickers hardness more than five times that of the electromagnetic steel sheet, making manufacturing very difficult and costly. A rotating electrical machine that solves this problem is disclosed in Patent Document 1.

[0003] In the rotating electrical machine of Patent Document 1, the iron core (stator core) of the stator is divided into an annular back yoke having a plurality of recesses on the inner peripheral surface and a plurality of teeth, one end of which is fitted into the recess and the other end of which protrudes toward the rotor core. The plurality of teeth are formed by cutting an amorphous metal foil strip into a trapezoidal shape and laminating them.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the rotating electrical machine of Patent Document 1 does not consider the iron loss caused by the gap formed between the plurality of recesses of the back yoke and one end of the plurality of teeth fitted into the plurality of recesses, and there is room for improvement from the viewpoints of high efficiency and high output.

[0006] An object of the present invention is to provide a rotating electrical machine capable of reducing iron loss due to a gap formed between a plurality of recesses of a back yoke and one end of a plurality of teeth fitted into the plurality of recesses.

Means for Solving the Problem

[0007] In order to achieve the above object, the present invention provides a rotating electrical machine including a rotor, a stator surrounding the outer periphery of the rotor, a first recess provided on the inner peripheral surface of the back yoke of the stator and extending in the axial direction of the stator, and teeth having one end fitted into the first recess, wherein a gap formed between the first recess and one end of the teeth fitted into the first recess is smaller in the circumferential direction of the stator than in the radial direction of the stator. <, the shortest distance between the side surface of the first concave portion and one end of the tooth is smaller than the shortest distance between the bottom surface of the first concave portion and one end of the tooth> .

Advantageous Effects of Invention

[0008] According to the present invention, it is possible to reduce iron loss due to a gap formed between a plurality of recesses in the back yoke and one ends of a plurality of teeth fitted into the plurality of recesses. Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of Drawings

[0009]

Figure 1

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Figure 11

Figure 12

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Figure 18

Embodiments for Carrying Out the Invention

[0010] Hereinafter, with reference to the drawings, the configuration and operation of the rotating electrical machine according to the first to sixth embodiments of the present invention will be described. In each figure, the same reference numerals indicate the same parts. Also, in each figure, the directions are specified by the XYZ axes orthogonal to each other, and +X is defined as "right", -X as "left", +Y as "up", -Y as "down", +Z as "front", and -Z as "rear".

[0011] (First Embodiment) FIG. 1 is a perspective view of a rotating electrical machine 1000 according to the first embodiment of the present invention, and FIG. 2 is a sectional view taken along the line A-A of the rotating electrical machine 1000 shown in FIG. 1. The rotating electrical machine 1000 is an inner-rotating radial-gap type rotating electrical machine, and includes a stator (stator) 100, a rotor (rotor) 200, a shaft 300, bearings 400, a first end bracket 500, a housing 600, and a second end bracket 700.

[0012] The stator 100 is a part that generates a magnetic force for rotating the rotor 200. The stator 100 is formed of a plurality of teeth 120 around which a coil 110 is wound and an annular back yoke 130 that connects the plurality of teeth 120. The back yoke 130 is fixed inside the cylindrical housing 600 by means such as press-fitting.

[0013] The rotor 200 is a part that rotates by the magnetic force generated from the stator 100. The rotor 200 is provided with a rotor core (rotor iron core) 210 composed of a plurality of laminated plates, a plurality of magnet accommodation holes (magnet accommodation portions) 211 formed in the rotor core 210, and a plurality of permanent magnets 220 accommodated in the plurality of magnet accommodation holes 211. A through hole 212 is provided at the center of the rotor core 210, and the shaft 300 is fixed to the through hole 212 by means such as press-fitting.

[0014] The shaft 300 is a shaft that rotates together with the rotor 200, and is rotatably supported by a bearing 400 fixed to the first end bracket 500 and a bearing 400 fixed to the second end bracket 700. The first end bracket 500 and the second end bracket 700 are attached to both sides in the axial direction of the housing 600, and close the openings located at both axial ends of the housing 600. The stator 100 and the rotor 200 are protected by the first end bracket 500, the housing 600, and the second end bracket 700.

[0015] When power is supplied to the stator 100 in the thus configured rotating electrical machine 1000, the shaft 300 rotates to become an electric motor, and when rotational power is supplied to the shaft 300, it becomes a generator.

[0016] Next, the stator 100 according to the present embodiment will be described in detail. FIG. 3 is a cross-sectional view of the stator 100. The stator 100 has a plurality of coils 110, a plurality of teeth 120 around which each of the plurality of coils 110 is wound, and a back yoke 130 to which the plurality of teeth 120 are attached to the inner peripheral wall.

[0017] Each of the plurality of coils 110 can be wound around each of the plurality of teeth 120 in a distributed winding manner with a rectangular flat wire as shown in FIG. 3, for example. Note that the coil 110 may use a round wire having a circular cross-sectional shape, or may be wound around the plurality of teeth 120 in a concentrated winding manner.

[0018] FIG. 4 is a perspective view of the tooth 120. As shown in this figure, the tooth 120 is a columnar iron core formed by laminating a plurality of thin plates 121. The tooth 120 has an upper surface 120a, a bottom surface 120b, a first bottom surface 120c, a second bottom surface 120d, a first inclined surface 122e, and a second inclined surface 122f.

[0019] FIG. 5 is a plan view of the thin plate 121. The thin plate 121 is a thin steel plate and is preferably formed of a low-loss soft magnetic material, for example, an amorphous metal. Further, as shown in FIG. 5, the planar shape of the thin plate 121 is preferably trapezoidal, and the trapezoid has a first base 121a, a second base 121b, a first leg 121c, and a second leg 121d.

[0020] The first base 121a forms a part of the first bottom surface 120c of the tooth 120, and its length is L1. The second base 121b forms a part of the second bottom surface 120d of the tooth 120, and its length is L2. The first base 121a and the second base 121b may be parallel as shown in FIG. 5. In this case, the length L1 of the first base 121a is larger than the length L2 of the second base 121b.

[0021] The first leg 121c is the hypotenuse connecting the +X (right) side end of the first base 121a and the +X (right) side end of the second base 121b. Further, the first leg 121c forms a part of the first inclined surface 122e of the tooth 120, and its length is L3. The second leg 121d is the hypotenuse connecting the -X (left) side end of the first base 121a and the -X (left) side end of the second base 121b. Further, the second leg 121d forms a part of the second inclined surface 122f of the tooth 120.

[0022] The first leg 121c and the second leg 121d may be line-symmetrical with respect to a straight line CL passing through the midpoints of the first base 121a and the second base 121b as shown in FIG. 5. In this case, the lengths of the first base 121a and the second base 121b are the same length L3. Further, the angles formed by the first base 121a and the second base 121b with the straight line CL are the same angle θ.

[0023] FIG. 6 is a partially enlarged view when the back yoke 130 is viewed from above along the axial direction of the stator. In this paper, FIG. 6 may sometimes be referred to as the front view of the back yoke 130. The back yoke 130 is a cylindrical core formed by laminating electromagnetic steel sheets 131 punched out in an annular shape. As shown in FIG. 6, a plurality of first recesses 133 extending along the axial direction of the stator 100 are provided on the inner peripheral wall 132 of the back yoke 130. Each of the plurality of first recesses 133 includes a bottom surface 133a, a first side wall (first side surface) 135b that rises from one end in the circumferential direction of the stator 100 of the bottom surface 133a toward the center of the stator 100, a second side wall (second side surface) 135c that rises from the other end in the circumferential direction of the stator 100 of the bottom surface 133a toward the center of the stator 100, and a second recess 133d provided on the bottom surface 133a and extending along the axial direction of the stator 100.

[0024] The width of the bottom surface 133a in the cross section of the back yoke 130 is W1.

[0025] In this embodiment, the second recess 133d is provided on the bottom surface 133a, but the second recess 133d may be omitted. In this case, the bottom surface 133a may be, for example, a plane that intersects substantially perpendicularly with respect to a normal line (hereinafter referred to as the normal line NL) passing through the center of the bottom surface 133a among the normal lines of the peripheral surface 134 of the back yoke 130.

[0026] The first side wall 135b and the second side wall 135c are two side surfaces sandwiching the bottom surface 133a, and may be line-symmetrical with respect to the normal line NL. In that case, the lengths of the first side wall 135b and the second side wall 135c are the same length L4. Also, the angles formed by the first side wall 135b and the second side wall 135c with the normal line NL are the same angle θ.

[0027] As shown in FIG. 6, it is preferable to form the first recess 133 such that the distance between the first side wall 135b and the second side wall 135c in the circumferential direction of the back yoke 130 (stator 100) (the width of the first recess 133) decreases toward the center of the back yoke 130 (the center of the stator 100). In this case, the width W2 of the opening end of the first recess 133 appearing on the inner peripheral wall 132 of the back yoke 130 is smaller than the width W1 of the bottom surface 133a of the first recess 133.

[0028] The second recess 133d is a recess having a substantially arc-shaped cross section formed, for example, at the center in the circumferential direction of the stator 100 on the bottom surface 133a of the first recess 133, and extends along the axial direction of the back yoke 130. The width of the second recess 133d is denoted as W3.

[0029] FIG. 7 is an enlarged view of the teeth 120 with one end (the end on the side of the first bottom surface 120c) fitted into the first recess 133 of the back yoke 130.

[0030] As shown in this figure, the width Wa of the first recess 133 in the circumferential direction of the stator 100 may be monotonically decreased toward the center of the stator 100. Also, the width Wb of the teeth 120 in the circumferential direction of the stator 100 may be monotonically decreased from one end of the teeth 120 (the end on the side of the first bottom surface 120c (the first end)) toward the other end of the teeth (the end on the side of the second bottom surface 120d (the second end)).

[0031] As is clear from FIG. 7, the length L1 of the first base 121a of the teeth 120 (see FIG. 5) is smaller than the width W1 of the bottom surface 133a of the first recess 133 (see FIG. 6).

[0032] Also, the length L1 of the first base 121a of the teeth 120 (see FIG. 5) is larger than the width W2 of the opening of the first recess 133 (see FIG. 6). Thereby, one end (the end on the side of the first bottom surface 120c) of the teeth 120 is fitted into the first recess 133 and cannot fall off in the inner diameter direction of the back yoke 130 from the first recess 133.

[0033] The tooth 120 is fixed to the back yoke 130 such that a gap 140 is formed between the first recess 133 and one end of the tooth 120 (the end on the side of the first bottom surface 120c) fitted in the first recess 133. As the gap 140, a radial gap 141 and two circumferential gaps 142 (a first circumferential gap 142a and a second circumferential gap 142b) can be formed.

[0034] The radial gap 141 is a gap formed between the first bottom surface 120c of the tooth 120, the bottom surface 133a of the first recess 133, and the second recess 133d. The first circumferential gap 142a is a gap formed between the first inclined surface 122e of the tooth 120 and the first side wall (first side surface) 135b of the first recess 133. The second circumferential gap 142b is a gap formed between the second inclined surface 122f of the tooth 120 and the second side wall (second side surface) 135c of the first recess 133.

[0035] At least one of the two circumferential gaps 142 is smaller than the radial gap 141. That is, the distances between the side walls 135b, 135c of the first recess 133 and the inclined surfaces 122e, 122f of the tooth 120 are smaller (shorter or closer) than the distance between the bottom surface 133a of the first recess 133 and the first bottom surface 120c of the tooth 120. The comparison of the magnitudes of the distances may be made by comparing the shortest distance between the side walls 135b, 135c of the first recess 133 and the inclined surfaces 122e, 122f of the tooth 120 with the shortest distance between the bottom surface 133a of the first recess 133 and the first bottom surface 120c of the tooth 120. For example, when the second recess 133d is provided on the bottom surface 133a of the first recess 133 as shown in FIG. 7, the distance between the bottom surface 133a and the first bottom surface 120c of the tooth 120, rather than the distance between the second recess 133d and the first bottom surface 120c of the tooth 120, is adopted as the object of comparison with the shortest distance between the side walls 135b, 135c and the inclined surfaces 122e, 122f of the tooth 120.

[0036] [Effect] When the rotating electrical machine 1000 is configured in this way, the magnetic flux that has flowed through the teeth 120 from the other end side (second end portion) to the one end side (first end portion) of the teeth 120 flows through the inclined surfaces 122e and 122f of the teeth 120 to the convex portion (the convex portion between two adjacent first recesses 133) of the back yoke 130. As a result, it is possible to reduce the concentration of magnetic flux around the first recess 133 in the back yoke 130, and thus it is possible to reduce the iron loss generated in the back yoke 130. In particular, in this embodiment, since the teeth 120 are formed of amorphous metal, the iron loss can be further reduced.

[0037] Therefore, according to this embodiment, since the iron loss caused by the gap between the back yoke 130 and the teeth 120 can be reduced, it is possible to improve the efficiency and increase the output of the rotating electrical machine 1000.

[0038] From the viewpoint of further reducing the iron loss, at least one of the two circumferential gaps 142 is preferably zero, that is, at least one of the two inclined surfaces 122e and 122f of the teeth 120 is preferably brought into contact with the side walls 135b and 135c of the corresponding first recess 133. When the inclined surface 122 (for example, the inclined surfaces 122e and 122f) and the opposing side wall 135 (for example, the side walls 135b and 135c) are brought into contact in this way, magnetic flux easily flows from the inclined surface 122 of the teeth 120 to the convex portion (the convex portion between two adjacent first recesses 133) of the back yoke 130. As a result, the iron loss of the rotating electrical machine 1000 can be reduced.

[0039] Subsequently, the effects of this embodiment will be described in more detail with reference to FIG. 8. FIG. 8 is a table showing the results of analyzing the magnetic flux distribution and the influence on the iron loss due to the position of the gap formed between the teeth 120 and the back yoke 130 of the rotating electrical machine according to this embodiment. Note that, unlike that in FIG. 7, the first recess 133 of the back yoke 130 in FIG. 8 is not provided with the second recess 133d.

[0040] "Gap position" in FIG. 8 indicates the types of positions of the gaps formed between the teeth 120 and the back yoke 130, and here, three types of <1> to <3> are exemplified.

[0041] The "no gap" in <1> means that there is no gap between the tooth 120 and the back yoke 130 (that is, when there is no radial gap 141 and two circumferential gaps 142), and one end of the tooth 120 is in close contact with the bottom surface 133a of the first recess 133 and each of the two side walls 135b, 135c. However, when actually manufacturing the rotating electrical machine, since it is necessary to form the first recess 133 larger than one end of the tooth 120, it is very difficult to fit the tooth 120 and the first recess 133 without any gap as in <1>.

[0042] The "radial gap" in <2> is a case close to the above-described embodiment in which there is a radial gap 141 but no two circumferential gaps 142 (142a, 142b). That is, the first bottom surface 120c of the tooth 120 and the bottom surface 133a of the first recess 133 are separated from each other, and a radial gap 141 is formed. However, the first inclined surface 122e of the tooth 120 and the first side wall 135b of the first recess 133, and the second inclined surface 122f of the tooth 120 and the second side wall 135c of the first recess 133 are in close contact with each other.

[0043] The "circumferential gap" in <3> is a case where there is no radial gap 141 but there are two circumferential gaps 142 (142a, 142b). That is, the first bottom surface 120c of the tooth 120 and the bottom surface 133a of the first recess 133 are in close contact with each other. However, the first inclined surface 122e of the tooth 120 and the first side wall 135b of the first recess 133, and the second inclined surface 122f of the tooth 120 and the second side wall 135c of the first recess 133 are separated from each other, and a circumferential gap 142 is formed.

[0044] Compare the "magnetic flux distribution" and "iron loss" at each gap position of <1> to <3>.

[0045] In the case of <1>, the magnetic flux entering from the second bottom surface 120d (the other end) of the tooth 120 passes through the portion where the first inclined surface 122e of the tooth 120 and the first side wall 135b of the first recess 133 are in contact, and flows into the adjacent tooth 120 and the back yoke 130. When the iron loss in this case is taken as the reference (1.00), in the case of <2> which is close to this embodiment, it shows a magnetic flux distribution almost equivalent to that of <1>, and its iron loss is 1.03, which is almost equivalent to that of <1>.

[0046] On the other hand, in the case of <3>, the magnetic flux entering from the second bottom surface 120d of the tooth 120 passes through the portion where the first bottom surface 120c of the tooth 120 and the bottom surface 133a of the first recess 133 are in close contact, and most of it flows to the outer peripheral side of the back yoke 130. That is, since the magnetic flux density on the outer peripheral side of the back yoke 130 increases as compared with the cases of <1> and <2>, the iron loss becomes 1.3, which is actually 1.30 times the iron loss of <1>.

[0047] As is clear from this analysis result, if the distance between the side walls 135b and 135c of the first recess 133 and the inclined surfaces 122e and 122f of the tooth 120 is made smaller than the distance between the bottom surface 133a of the first recess 133 and the first bottom surface 120c of the tooth 120, the increase in magnetic flux density can be reduced, and the iron loss of the back yoke 130 can be reduced. That is, the iron loss of the back yoke 130 can be made closer to the ideal case of <1>. Note that the planar shape of the thin plate 121 is trapezoidal. Therefore, a steel plate of a soft magnetic material such as amorphous metal can be easily processed.

[0048] (Second Embodiment) As described above, from the viewpoint of further reducing the iron loss, it is preferable that the side surfaces (the first side wall 135b and the second side wall 135c) of the first recess 133 and one end of the tooth 120 (the first inclined surface 122e and the second inclined surface 122f on the first bottom surface 120c side) are in contact.

[0049] Therefore, in the present embodiment, a thermosetting resin 150 is filled into the gap (see FIG. 7) between the first bottom surface 120c of the teeth 120 and the second recess 133d of the back yoke 130 by transfer molding. That is, the resin 150 is filled into the gap (radial gap 141) formed between the first recess 133 and one end of the teeth 120 (the end on the side of the first bottom surface 120c) fitted into the first recess 133, and contacts the bottom surface 133a of the first recess 133 and the end surface (the first bottom surface 120c) of one end of the teeth facing the bottom surface 133a of the first recess 133.

[0050] FIG. 9 is a diagram showing, together with an enlarged view of the stator 100 in which the resin 150 is filled in the gap between the first recess 133 of the back yoke 130 and the first bottom surface 120c of the teeth 120, an example of the density distribution of the resin 150 in a graph.

[0051] Generally, the density of the resin 150 filled in the gap by transfer molding has a positive correlation with the pressure applied to each of the resins 150 during the molding process. Therefore, in a place where the width of the gap is wide, more resin 150 flows in than in a place where the width of the gap is narrow, the pressure of the resin 150 becomes relatively large, and the density of the resin 150 becomes relatively high. As a result, in a place where the width of the gap is narrow, the density of the resin 150 becomes relatively low.

[0052] In the present embodiment, the first radial gap 141a formed between the second recess 133d and the first bottom surface 120c corresponds to a place where the width of the gap is wide. Further, the second radial gap 141b formed between the remaining bottom surface 133a of the first recess 133 excluding the portion where the second recess 133d is provided and one end of the teeth 120 (the first bottom surface 120c) corresponds to a place where the width of the gap is narrow. Therefore, in the stator 100 according to the present embodiment, the density distribution of the resin 150 filled in the gap between the bottom surface 133a of the back yoke 130 and the first bottom surface 120c of the teeth 120 becomes the graph shown in the lower part of FIG. 9.

[0053] In the graph of FIG. 9, since the density is highest at the center of the first recess 133, a large force F for pressing the teeth 120 toward the center of the stator 100 can be generated at the center of the first recess 133. This pressing force F moves the teeth 120 toward the center of the stator 100 (in the inner diameter direction of the back yoke 130), and finally, as shown in FIG. 10, the inclined surfaces 122e and 122f of the teeth 120 can be brought into close contact with the side walls 135b and 135c of the first recess 133.

[0054] FIG. 10 is a partially enlarged view of the stator core showing a state in which the inclined surfaces 122e and 122f of the teeth 120 are in contact with the side walls 135b and 135c of the first recess 133 by filling the resin 150 in the gap between the first recess 133 of the back yoke 130 and the first bottom surface 120c of the teeth 120.

[0055] The angles formed by the first inclined surface 122e and the second inclined surface 122f of the teeth 120 with the straight line CL (see FIGS. 4 and 5), and the angles formed by the first side wall 135b and the second side wall 135c of the first recess 133 with the normal line NL (see FIG. 6) are the same angle θ. Therefore, each of the first inclined surface 122e and the second inclined surface 122f of the teeth 120 is in close contact with each of the first side wall 135b and the second side wall 135c of the back yoke 130. Thus, the gap 140 formed between the first recess 133 and one end of the teeth 120 fitted in the first recess 133 is smaller in the circumferential direction of the stator 100 than in the radial direction of the stator 100.

[0056] Note that the resin 150 filled in the gap between the teeth 120 and the back yoke 130 is heated and cured. As a result, the state where the gap 140 formed between the first recess 133 and one end of the teeth 120 fitted in the first recess 133 is smaller in the circumferential direction of the stator 100 than in the radial direction of the stator 100 is maintained.

[0057] When the resin 150 is filled in the gap 140 as in the present embodiment to bring the inclined surfaces 122e and 122f of the teeth 120 into close contact with the side walls 135b and 135c of the first recess 133, the possibility of chipping or cracking occurring in the teeth 120 and the first recess 133 is reduced as compared with the case where a wedge or the like is press-fitted into the gap 140.

[0058] Further, in the present embodiment, by changing the width of the gap 140 in which the resin 150 is filled and the size of the second recess 133d, the pressing force by the resin 150 can be adjusted. Thereby, it is possible to reduce the excessive pressure applied to the surface to be brought into close contact, and it is possible to reduce the deterioration of the magnetic characteristics of the teeth 120 and the back yoke 130.

[0059] (Third Embodiment) In the present embodiment, the preferable value of the embedding depth L5 of the teeth 120 with respect to the first recess 133 in the second embodiment will be described with reference to FIG. 11.

[0060] FIG. 11 is a schematic diagram showing the relationship between the embedding depth L5 of the teeth 120 with respect to the first recess 133 and the width L2 of the other end (the second bottom surface 120d) of the teeth 120 in the circumferential direction of the stator 100.

[0061] The embedding depth L5 indicates the length of the portion where the side walls 135b and 135c of the first recess 133 are in contact with the inclined surfaces 122e and 122f of the teeth 120 in the cross section of the back yoke 130. As shown by the formula in FIG. 11, the embedding depth L5 is preferably greater than half of the width L2 of the second bottom surface 120d of the teeth 120.

[0062] By setting the embedding depth L5 in this way, it is possible to further reduce the concentration of magnetic flux around the first recess 133 in the back yoke 130, and it is possible to reduce the iron loss of the back yoke 130.

[0063] Although FIG. 11 shows only the magnetic flux B passing through the portion where the first inclined surface 122e and the second side wall 135c are in close contact, it goes without saying that there is a magnetic flux passing through the portion where the second inclined surface 122f and the second side wall 135c are in close contact.

[0064] (Fourth Embodiment) FIG. 12 is a partially enlarged view of a stator 100 filled with resin in the rotating electrical machine according to the present embodiment. The difference between the stator 100 according to the present embodiment and the stator 100 according to the first embodiment is that the resin 150 further covers the side walls (the first inclined surface 122e and the second inclined surface 122f) in the circumferential direction of the stator (stator) 100 of the teeth 120. Specifically, the stator 100 according to the present embodiment is covered with a molded resin 151, and the molded resin 151 is filled in the radial gap 141 and between two adjacent teeth 120.

[0065] As shown in FIG. 12, when the width of the first inclined surface 122e of the tooth 120 is L3 and the angle formed by the normal line NL to the circumferential surface 134 of the back yoke 130 passing through the center of the first inclined surface 122e and the second inclined surface 122f is θ, the width W3 of the second recess 133d preferably satisfies W3 > 2×L3sinθ.

[0066] Assume that the pressure P applied to the first bottom surface 120c, the first inclined surface 122e, and the second inclined surface 122f by the resin 150 is constant. In this case, the force Fa that presses the tooth 120 applied to the first bottom surface 120c in the inner diameter direction of the back yoke 130 is P×W3×(axial length). On the other hand, the force Fb that presses the tooth 120 applied to each of the first inclined surface 122e and the second inclined surface 122f in the outer diameter direction of the back yoke 130 is P×L3×(axial length)×sinθ.

[0067] In order to closely contact the side surfaces (the first side wall 135b and the second side wall 135c) of the first recess 133 and one end of the tooth 120 (the first inclined surface 122e and the second inclined surface 122f on the first bottom surface 120c side), Fa > 2Fb must be satisfied. As a result, W3 > 2×L3sinθ.

[0068] Note that since the coil 110 and the insulator are inserted into the slot portion (between two adjacent teeth 120), the pressure exerted by the resin 150 on the first inclined surface 122e and the second inclined surface 122f is reduced compared to the pressure exerted by the resin 150 on the first bottom surface 120c. Therefore, "W3 > 2×L3sinθ" is the dimensional condition calculated on the safe side.

[0069] In this way, even if a force Fb that pushes the teeth 120 in the outer diameter direction of the back yoke 130 is generated in the rotating electrical machine that satisfies "W3 > 2×L3sinθ" compared to the integral molding, the teeth 120 are pressurized in the inner diameter direction of the back yoke 130. Therefore, a force acts so that the side surfaces (the first side wall 135b and the second side wall 135c) of the first recess 133 and one end of the teeth 120 (the first inclined surface 122e and the second inclined surface 122f on the side of the first bottom surface 120c) are in close contact.

[0070] Next, a method for manufacturing the stator 100 according to the present embodiment will be described. FIG. 13 is a cross-sectional view of a mold 800 used for manufacturing the rotating electrical machine according to the present embodiment and the stator 100 installed in the mold 800 for filling the mold resin 151. FIG. 14 is a cross-sectional view of a mold 800 used for manufacturing the rotating electrical machine according to the present embodiment and the stator 100 installed in the mold 800 and filled with the mold resin 151. FIG. 15 is a schematic diagram in which the position in the axial direction of the stator of the resin injection port 831 provided in the upper mold 830 of the mold 800 used for manufacturing the rotating electrical machine according to the present embodiment is projected onto the stator 100.

[0071] The mold 800 includes a cylindrical core mold 810 disposed on the inner circumference of the stator, a lower mold 820 disposed on the bottom surface of the stator, and an upper mold 830 disposed on the upper surface of the stator and having a gate 831 that serves as an injection port for the resin 150. The gate 831 is located above the outer diameter side of the stator 100 or directly above the second recess 133d (directly above in FIG. 15) from the second recess 133d, and a plurality of gates 831 are provided evenly in the circumferential direction of the stator 100.

[0072] As shown in FIG. 14, pressure is applied to a resin 150, which has been previously stored in a pot or the like, heated, and has fluidity, from above the upper mold 830 with a plunger (not shown). The resin 150 is extruded from the gate 831 into the stator 100 and within the mold 800, and reaches the lower mold 820 through the gaps between the second recess 133d and the coils 110.

[0073] When the resin 150 is filled in the stator 100 to a certain extent, the pressure from the plunger (not shown) propagates to the resin 150 within the stator 100, and gradually the pressure of the resin 150 rises. As a result, the excess air within the stator 100 escapes through the gaps of the mold 800, and the resin 150 is filled up to narrow locations such as between the coils 110. After the filling is completed, the stator 100 integrated with the resin mold is completed by heat curing. Note that the resin 150 may be filled into the stator 100 by transfer molding.

[0074] In the mold according to the present embodiment, since the position of the gate 831 is provided above the second recess 133d, it becomes easier for the resin 150 to be filled from the second recess 133d, and it becomes more difficult for the resin 150 to enter the fitting portion (the portion where the first inclined surface 122e and the second side wall 135c face each other, and the portion where the second inclined surface 122f and the second side wall 135c face each other). Even if the resin 150 enters the fitting portion, ultimately the resin 150 is extruded by the load in the inner diameter direction of the stator 100 acting on the teeth 120. However, since it is difficult to completely extrude it, by filling the resin 150 from the second recess 133d and closing the gap of the fitting portion at an early stage, the closeness of the fitting portion can be further enhanced.

[0075] When integrally molding the resin 150 with a mold resin, as in the first embodiment, it is not necessary to fill the resin 150 for each second recess 133d. Therefore, the man-hours for resin filling can be reduced. Note that the above effect can be obtained if the position of the gate 831 is provided on the outer diameter side of the second recess 133d. Therefore, it does not have to be directly above the second recess 133d.

[0076] (Fifth Embodiment) FIG. 16 is a partially enlarged view of the stator of the rotating electrical machine according to the present embodiment. The difference between the stator 100 according to the present embodiment and the stator 100 according to the first embodiment lies in the number and position of the second recesses 133d provided on the bottom surface 133a of the first recess 133 of the back yoke 130. That is, the second recesses 133d are provided at both ends of the bottom surface 133a of the first recess 133 in the cross section of the back yoke 130. Therefore, two second recesses 133d are provided on the bottom surface 133a of the first recess 133.

[0077] By providing the second recesses 133d at both ends of the bottom surface 133a, when the teeth 120 are inserted into the first recess 133 of the back yoke 130, it is possible to reduce the interference between the corners 120g of the teeth 120 and the bottom surface 133a of the first recess 133. Further, even when interference occurs, the frictional force generated at the corners 120g of the teeth 120 can be reduced. From these, the workability of assembly can be improved.

[0078] (Sixth Embodiment) FIG. 17 is a partially enlarged view of the stator 100 of the rotating electrical machine according to the present embodiment before the foamed resin 152 provided in the second recess 133d foams. FIG. 18 is a partially enlarged view of the stator 100 according to the present embodiment after the foamed resin 152 provided in the second recess 133d has foamed.

[0079] The difference between the stator 100 according to the present embodiment and the stator 100 according to the first embodiment is that the resin is the foamed resin 152. The foamed resin 152 is, for example, an insulating epoxy foamed resin, and is applied in advance to the second recess 133d of the back yoke 130 before the teeth 120 are inserted into the first recess 133 of the back yoke 130. Then, after the teeth 120 are inserted into the first recess 133 of the back yoke 130, the foamed resin 152 foams by heating and then cures. When the foamed resin 152 foams, the teeth 120 are pushed out in the inner diameter direction of the back yoke 130.

[0080] The rotating electrical machine according to this embodiment can bring the teeth 120 and the back yoke 130 into close contact with each other in the circumferential direction without applying an excessive shearing force to the teeth 120 and the back yoke 130, so that a motor with low vibration and noise, high efficiency, and high output can be provided. In addition, the teeth 120 can be easily inserted into the second recess 133d provided with the foamed resin 152 before foaming. Therefore, the workability is excellent.

[0081] Note that the material of the foamed resin 152 and the shape of the second recess 133d are not limited to this embodiment. A sheet-like foamed resin may be attached to the second recess 133d. In that case, the shape of the second recess 133d can be made rectangular to facilitate the attachment of the sheet. Also, the foamed resin 152 may be provided on the first bottom surface 120c of the teeth 120.

[0082] Note that the present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Also, for a part of the configuration of each embodiment, addition, deletion, or replacement with other configurations is possible.

Explanation of Reference Numerals

[0083] 100... stator (stator), 110... coil, 120... teeth, 120c... first bottom surface, 122e... first inclined surface (side wall), 122f... second inclined surface (side wall), 130... back yoke, 133... first recess, 133a... bottom surface, 135b... first side wall, 135c... second side wall, 133d... second recess, 140... gap, 141a... first radial gap, 141b... second radial gap, 150... resin, 151... mold resin, 152... foamed resin, 200... rotor (rotor), 800... mold, 1000... rotating electrical machine

Claims

1. A rotor, A stator surrounding the outer periphery of the rotor, A first recess provided on the inner peripheral surface of the back yoke of the stator and extending in the axial direction of the stator, A rotating electrical machine comprising teeth having one end fitted into the first recess, A gap formed between the first recess and one end of the teeth fitted into the first recess is smaller in the circumferential direction of the stator than in the radial direction of the stator, The shortest distance between the side surface of the first recess and one end of the teeth is smaller than the shortest distance between the bottom surface of the first recess and one end of the teeth. The rotating electrical machine is characterized by this.

2. A rotor, A stator surrounding the outer periphery of the rotor, A first recess provided on the inner peripheral surface of the back yoke of the stator and extending in the axial direction of the stator, A rotating electrical machine comprising teeth having one end fitted into the first recess, A gap formed between the first recess and one end of the teeth fitted into the first recess is smaller in the circumferential direction of the stator than in the radial direction of the stator, The width of the first recess in the circumferential direction of the stator decreases toward the center of the stator, The width of the teeth in the circumferential direction of the stator decreases from one end of the teeth toward the other end of the teeth. The rotating electrical machine is characterized by this.

3. A rotor, A stator surrounding the outer periphery of the rotor, A first recess provided on the inner peripheral surface of the back yoke of the stator and extending in the axial direction of the stator, A rotating electrical machine comprising teeth having one end fitted into the first recess, A gap formed between the first recess and one end of the teeth fitted into the first recess is smaller in the circumferential direction of the stator than in the radial direction of the stator, The teeth are formed of a low-loss soft magnetic material, A rotating electrical machine, characterized in that an area of a portion where one end of the teeth faces the first recess in a circumferential direction of the stator is larger than an area of the other end of the teeth.

4. A rotor, A stator surrounding an outer periphery of the rotor, A first recess provided on an inner peripheral surface of a back yoke of the stator and extending in an axial direction of the stator, A rotating electrical machine including teeth having one end fitted into the first recess, A gap formed between the first recess and one end of the teeth fitted into the first recess is smaller in a circumferential direction of the stator than in a radial direction of the stator, The gap formed between the first recess and one end of the teeth fitted into the first recess is filled with a resin that contacts a bottom surface of the first recess and an end surface of one end of the teeth facing the bottom surface of the first recess, A second recess extending in the axial direction of the stator is provided on the bottom surface of the first recess, The resin is filled in a first gap formed between the second recess and one end of the teeth and a second gap formed between a remaining bottom surface excluding a portion where the second recess is provided from the bottom surface of the first recess and one end of the teeth. A rotating electrical machine characterized by this.

5. A rotating electrical machine according to any one of claims 2 to 4, A rotating electrical machine, characterized in that a distance between a side surface of the first recess and one end of the teeth is smaller than a distance between a bottom surface of the first recess and one end of the teeth.

6. A rotating electrical machine according to any one of claims 1 to 4, A rotating electrical machine, characterized in that a side surface of the first recess and one end of the teeth are in contact with each other.

7. A rotating electrical machine according to any one of claims 1, 2, and 4, A rotating electrical machine, wherein the teeth are formed of a low-loss soft magnetic material. **Claim 8** A rotating electrical machine according to any one of claims 1 to 3, wherein a resin that contacts the bottom surface of the first recess and the end surface of one end of the teeth fitted in the first recess is filled in a gap formed between the first recess and one end of the teeth fitted in the first recess. **Claim 9** A rotating electrical machine according to claim 8, wherein the resin further covers the side wall of the teeth in the circumferential direction of the stator. **Claim 10** A rotating electrical machine according to claim 4, where the width of the inclined surface of the teeth is L, when the angle formed by each of the two side walls of the teeth in the circumferential direction of the stator with the normal to the circumferential surface of the back yoke passing through the center of the two side walls is θ, where the width W of the second recess in the cross section of the stator is W > L × sinθ × 2 A rotating electrical machine characterized by this. **Claim 11** A rotating electrical machine according to claim 8, wherein the resin is formed of a thermosetting resin or a foamed resin. **Claim 12** A rotating electrical machine according to claim 4, wherein the second recess is provided at both ends of the bottom surface of the first recess. **Claim 13** A rotating electrical machine according to claim 3, wherein the teeth are trapezoidal columns. **Claim 14** A rotating electrical machine according to claim 7, wherein the teeth are trapezoidal columns.

15. A method for manufacturing a rotating electrical machine according to claim 4, wherein the stator is covered with a mold having a resin injection port located above the outer diameter side of the stator or directly above the second recess from the second recess, and the stator is resin-molded by injecting resin into the resin injection port.

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