Stator

Abstract

To provide an inexpensive stator which can reduce torque ripples while suppressing reduction in torque and increase in core loss of the stator.SOLUTION: A stator 10 comprises: a stator core 11 having a plurality of teeth 110 circumferentially aligned; and an excitation coil 12 wound around the teeth 110. The stator core 11 is formed by laminating a first electromagnetic steel plate 116 and a second electromagnetic steel plate 117. The first electromagnetic steel plate 116 has a magnetic wedge 13 which couples the two circumferentially adjacent teeth 110. The magnetic wedge 13 is disposed between the coil 12 and a rotor which is provided rotatably with respect to the stator core 11. The second electromagnetic steel plate 117 has an opening on the rotor side between the two circumferentially adjacent teeth 110.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] This invention relates to a stator.

Background Art

[0002] As a rotating electric machine, for example, a synchronous motor (hereinafter referred to as an electric motor) includes a stator around which an exciting coil is wound, and a rotor rotatably provided with respect to the stator. The stator has a plurality of teeth arranged in the circumferential direction. Slots are formed between adjacent teeth in the circumferential direction. A coil is inserted into this slot and wound around each tooth. When the coil is energized, a predetermined interlinking magnetic flux is formed in each tooth. A magnetic attractive force or repulsive force is generated between this interlinking magnetic flux and, for example, a magnet provided on the rotor, and the rotor is continuously rotated.

[0003] Here, in order to reduce torque ripple caused by the slots of the electric motor, a technique of providing a magnetic wedge that connects teeth arranged in the circumferential direction is known. The magnetic wedge is disposed between the coil and the rotor. By the way, due to the influence of the magnetic wedge, the torque may decrease or the iron loss of the stator may increase. For this reason, a technique is disclosed in which a convex portion is formed on the side of the magnetic wedge facing the rotor, and by making the shape of the convex portion a predetermined shape, an increase in torque reduction and iron loss of the stator is suppressed while reducing torque ripple.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the above prior art, when changing the shape of the convex portion, it is necessary to change the tool for forming the magnetic wedge. For this reason, there has been a problem of high processing cost in order to derive an optimal shape of the convex portion that can suppress a decrease in torque and an increase in iron loss of the stator while reducing torque ripple.

[0006] Therefore, the present invention provides an inexpensive stator that can suppress a decrease in torque and an increase in iron loss of the stator while reducing torque ripple. Subsequently, it provides a stator that can contribute to energy efficiency improvement.

Means for Solving the Problems

[0007] In order to solve the above problems, the present invention proposes the following means. (1) The stator according to the present invention (for example, the stator 10 of the embodiment) includes a stator core (for example, the stator core 11 of the embodiment) having a plurality of teeth (for example, the teeth 110 of the embodiment, the first tooth steel plate 116T, the second tooth steel plate 117T) arranged in the circumferential direction, and an exciting coil (for example, the coil 12 of the embodiment) wound around the teeth. The stator core is formed by laminating a first steel plate (for example, the first electromagnetic steel plate 116 of the embodiment) and a second steel plate (for example, the second electromagnetic steel plate 117 of the embodiment). The first steel plate has a magnetic wedge (for example, the magnetic wedge 13 of the embodiment) that connects two adjacent teeth in the circumferential direction. The magnetic wedge is disposed between a rotor (for example, the rotor 20 of the embodiment) rotatably provided with respect to the stator core and the coil. The second steel plate has an opening on the rotor side between two adjacent teeth in the circumferential direction.

[0008] By configuring in this way, when laminating the first steel plate and the second steel plate, without changing the shape of the magnetic wedge, the occupation ratio of the magnetic wedge can be adjusted only by adjusting the respective ratios. By adjusting the occupation ratio, while suppressing a decrease in torque and an increase in iron loss of the stator, the magnetic wedge can be easily optimized to reduce torque ripple. Therefore, the processing cost of the stator can be reduced. Consequently, it can contribute to energy efficiency at low cost.

[0009] (2) In the above configuration, the magnetic wedge has a convex portion (for example, the convex portion 131 of the embodiment) provided on the rotor side, and the convex portion has a facing surface (for example, the facing surface 13A of the embodiment) facing the rotor in the radial direction, and side surfaces (for example, the side surfaces 13B of the embodiment) extending in a direction away from the rotor from both circumferential sides of the facing surface, and the side surfaces may be spaced apart from the teeth.

[0010] By configuring in this way, it is possible to gently change the circumferential distribution change of the magnetic flux density at the rotor-side end portions in the magnetic wedge and the teeth. Therefore, while reliably suppressing a decrease in torque and an increase in iron loss of the stator, torque ripple can also be reduced.

[0011] (3) In the above configuration, the magnetic wedge may be integrally formed with the first steel plate.

[0012] By configuring in this way, the processing cost of the stator can be reduced as compared with the case where the first steel plate and the magnetic wedge are formed separately.

[0013] (4) In the above configuration, the first steel plate and the second steel plate may be alternately laminated.

[0014] By configuring in this way, it is possible to easily form the stator core and further reduce the processing cost of the stator. Also, in the axial direction of the stator core (the lamination direction of each steel plate), since the density distribution of the magnetic wedge becomes constant, while reliably suppressing a decrease in torque and an increase in iron loss of the stator, torque ripple can also be reduced.

Advantages of the Invention

[0015] According to the present invention, it is possible to provide an inexpensive stator that can reduce torque ripple while suppressing a decrease in torque and an increase in iron loss of the stator. Consequently, it can contribute to energy efficiency improvement.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0017] Next, embodiments of the present invention will be described with reference to the drawings.

[0018] <Electric motor> FIG. 1 is a cross-sectional view showing a part of an electric motor 1 including a stator 10 according to an embodiment of the present invention. As shown in FIG. 1, the electric motor 1 includes a cylindrical stator 10 and a rotor 20 disposed at the radial center of the stator 10 and rotatably supported with respect to the stator 10. The electric motor 1 is, for example, a synchronous motor. In the present embodiment, the rotor 20 is composed of 8 poles. The cross-section shown in FIG. 1 is a cross-section along the radial direction. In FIG. 1, only a part corresponding to one pole of the rotor 20, that is, a circumferential angle region of 1 / 8 turn, is shown. In the following description, the direction parallel to the rotation axis P of the rotor 20 is simply referred to as the axial direction. The rotation direction of the rotor 20 is referred to as the circumferential direction. The radial direction of the rotor 20 orthogonal to the axial direction and the circumferential direction is simply referred to as the radial direction.

[0019] <Stator> FIG. 2 is an enlarged view of part II of FIG. 1. FIG. 3 is a perspective view of the stator 10 as viewed from the inner peripheral surface side. As shown in FIGS. 1 to 3, the stator 10 includes a stator core 11 having a plurality of teeth 110 and an exciting coil 12 wound around each tooth 110.

[0020] <Stator core> The stator core 11 has a cylindrical back yoke 11B. A plurality of teeth 110 project radially inward from the inner peripheral surface of the back yoke 11B. The plurality of teeth 110 are arranged at equal intervals in the circumferential direction. The cross-sectional shape of the teeth 110 along the radial direction is a rectangular shape that is long in the radial direction. The teeth 110 are formed uniformly along the axial direction.

[0021] Slots 11S are formed between the teeth 110 adjacent in the circumferential direction. In the present embodiment, for example, 48 teeth 110 and 48 slots 11S are formed respectively. Coils 12 are inserted into the respective slots 11S, and the coils 12 are wound around the corresponding teeth 110 respectively. Here, the stator core 11 is formed by alternately laminating two types of electromagnetic steel sheets 116 and 117 (first electromagnetic steel sheet 116, second electromagnetic steel sheet 117) in the axial direction. The two types of electromagnetic steel sheets 116 and 117 are formed by subjecting an electromagnetic steel sheet (not shown) serving as a base material to press working.

[0022] <First Electromagnetic Steel Sheet> FIG. 4 is a plan view of a part of the first electromagnetic steel sheet 116 as viewed from the axial direction. As shown in FIG. 4, the first electromagnetic steel sheet 116 of the two types of electromagnetic steel sheets 116 and 117 is integrally formed with a first back yoke steel sheet 116B that constitutes the back yoke 11B, a first tooth steel sheet 116T that constitutes the teeth 110, and a magnetic wedge 13 provided on the first tooth steel sheet 116T.

[0023] The first back yoke steel sheet 116B is formed in an annular shape as viewed from the axial direction. The first tooth steel sheet 116T protrudes radially inward from the inner peripheral edge of the first back yoke steel sheet 116B. The first tooth steel sheet 116T is formed in a rectangular shape that is long in the radial direction as viewed from the axial direction. Slots 11S are formed between two adjacent first tooth steel sheets 116T in the circumferential direction.

[0024] <Magnetic Wedge> As shown in detail in FIGS. 2 to 4, the magnetic wedge 13 is formed at the radially inner end of the first tooth steel sheet 116T so as to connect two adjacent first tooth steel sheets 116T in the circumferential direction. The magnetic wedge 13 closes the radially inner side of the slot 11S. The magnetic wedge 13 is integrally formed with the first tooth steel sheet 116T. The magnetic wedge 13 is formed simultaneously when the first electromagnetic steel sheet 116 is punched out from the electromagnetic steel sheet serving as a base material.

[0025] The magnetic wedge 13 is formed in a hat shape when viewed from the axial direction so as to be convex radially inward. Specifically, a concave portion 134 that is recessed radially inward is formed on the outer surface 13D on the radially outer side of the magnetic wedge 13. The concave portion 134 is formed in most of the center in the circumferential direction of the magnetic wedge 13. The magnetic wedge 13 has a convex portion 131 provided on the rotor 20 side (radially inward). The convex portion 131 has a facing surface 13A that faces the rotor 20 in the radial direction, and side surfaces 13B that extend in a direction away from the rotor 20 from both sides in the circumferential direction on the facing surface 13A.

[0026] The facing surface 13A is located on an extension surface M along the inner peripheral surface 113 of the stator 10 (the end surface on the radially inner side of the teeth 110). Hereinafter, the width in the circumferential direction on the facing surface 13A is referred to as the width of the convex portion 131. The side surfaces 13B are arranged at a distance from the circumferential side surfaces 111 of the teeth 110. In other words, the convex portion 131 is arranged with a gap therebetween and the side surfaces 111 of the teeth 110. Further, in other words, grooves 135 that are recessed radially outward from the facing surface 13A side are formed on both circumferential sides of the magnetic wedge 13.

[0027] <Second electromagnetic steel sheet> FIG. 5 is a plan view of a part of the second electromagnetic steel sheet 117 viewed from the axial direction. As shown in FIG. 5, the difference between the second electromagnetic steel sheet 117 and the first electromagnetic steel sheet 116 is that the first electromagnetic steel sheet 116 includes the magnetic wedge 13, while the second electromagnetic steel sheet 117 does not include the magnetic wedge 13. Specifically, the second electromagnetic steel sheet 117 is integrally formed by a second back yoke steel sheet 117B that constitutes the back yoke 11B and a second teeth steel sheet 117T that constitutes the teeth 110.

[0028] The second back yoke steel plate 117B is formed in an annular shape when viewed from the axial direction. The second back yoke steel plate 117B has the same shape as the first back yoke steel plate 116B. The second tooth steel plate 117T protrudes radially inward from the inner peripheral edge of the second back yoke steel plate 117B. The second tooth steel plate 117T is formed in a rectangular shape that is long in the radial direction when viewed from the axial direction. The second tooth steel plate 117T has the same shape as the first tooth steel plate 116T. A slot 11S is formed between two adjacent second tooth steel plates 117T in the circumferential direction. The slot 11S is open on the radially inner side (rotor 20 side).

[0029] Since the two electromagnetic steel plates 116 and 117 configured in this way are alternately laminated in the axial direction, the occupation ratio of the magnetic wedge 13 in the entire stator core 11 is about 50%. The occupation ratio of the magnetic wedge 13 refers to the ratio of the magnetic wedge 13 at the location where the magnetic wedge 13 is arranged in the entire stator core 11. That is, when the magnetic wedge 13 is arranged over the entire axial direction, that is, when the stator core 11 is formed by laminating the first electromagnetic steel plates 116 all provided with the magnetic wedge 13, the occupation ratio of the magnetic wedge 13 is 100%. On the contrary, when the stator core 11 is formed by laminating the second electromagnetic steel plates 117 all not provided with the magnetic wedge 13, the occupation ratio of the magnetic wedge 13 is 0%. Thus, the occupation ratio of the magnetic wedge 13 can be adjusted by adjusting the ratio of the first electromagnetic steel plate 116 and the second electromagnetic steel plate 117.

[0030] Such a magnetic wedge 13 prevents the coil 12 from falling off from each slot 11S, suppresses a decrease in the torque performance of the electric motor 1, reduces the iron loss of the stator 10, and suppresses torque ripple. Details of the action and effect of the magnetic wedge 13 will be described later.

[0031] <Coil> The coil 12 inserted into the slot 11S is located radially outside the magnetic wedge 13. That is, the magnetic wedge 13 is disposed at the radially inner end of the first tooth steel plate 116T and between the rotor 20 and the coil 12. The magnetic wedge 13 and the coil 12 are separated by a gap. Thereby, the insulation between the magnetic wedge 13 and the coil 12 is enhanced.

[0032] The coil 12 is, for example, a rectangular copper wire. When the coil 12 is a rectangular wire, the coil 12 aligns the short side in the cross section of the rectangular wire along the radial direction. Also, the coil 12 aligns the long side along the circumferential direction. In this state, the coils 12 are radially stacked and bundled in the slot 11S. Hereinafter, the width of the long side (circumferential width) of the coil 12 is referred to as the width of the unit coil 12. An insulating sheet is interposed between the coil 12 and the side surface 111 of the tooth 110. Thereby, insulation between the coil 12 and the tooth 110 is ensured. Also, the slot 11S is filled with an insulating material such as varnish.

[0033] <Operation of the electric motor and action of the magnetic wedge> Next, the operation of the electric motor 1 and the action of the magnetic wedge 13 will be described. When a predetermined coil 12 is energized, an interlinking magnetic flux is formed in the corresponding tooth 110. A magnetic attractive force or repulsive force is generated between this interlinking magnetic flux and the rotor 20, and the rotor 20 is continuously rotated.

[0034] Here, when the radially inner side of the slot 11S is open, a rapid change in the interlinking magnetic flux density occurs between the tooth 110 and the slot 11S. Due to this, the torque ripple increases. On the other hand, if the magnetic wedge 13 is provided so as to close the radially inner side of the slot 11S, a rapid change in the interlinking magnetic flux density between the tooth 110 and the slot 11S can be suppressed, so that the torque ripple can be suppressed.

[0035] However, simply providing the magnetic wedge 13 alone causes the interlinking magnetic flux passing through the magnetic wedge 13 to become mere leakage magnetic flux, and the magnetic flux from the rotor 20 becomes more likely to pass through the stator core 11. For this reason, the iron loss of the stator 10 increases, and torque ripple cannot be suppressed. In addition to this, the torque performance of the electric motor 1 also deteriorates. Therefore, in the present embodiment, the shape of the magnetic wedge 13 and the occupation ratio of the magnetic wedge 13 are adjusted. Thereby, while suppressing the deterioration of the torque performance of the electric motor 1, the iron loss of the stator 10 is reduced, and torque ripple is suppressed.

[0036] More specifically, since the side surface 13B of the convex portion 131 of the magnetic wedge 13 and the teeth 110 are separated from each other, it is possible to prevent the interlinking magnetic flux from concentrating on the inner peripheral surface 113 of the stator 10. For this reason, it is possible to smooth the change in the interlinking magnetic flux density that occurs between the vicinity of the inner peripheral surface 113 of the stator 10 and the vicinity of the radially inner end surface in the magnetic wedge 13. Further, the side surface 13B of the convex portion 131 of the magnetic wedge 13 and the teeth 110 are separated from each other. For this reason, it is possible to suppress the flow of the interlinking magnetic flux from the vicinity of the inner peripheral surface 113 of the stator 10 to the vicinity of the opposing surface 13A of the magnetic wedge 13. There is no unnecessary leakage of the interlinking magnetic flux from the magnetic wedge 13. As a result, it is possible to make the magnetic flux density in the vicinity of the inner peripheral surface 113 of the stator 10 approach uniformity in the circumferential direction. Therefore, the iron loss and torque ripple of the stator 10 can be suppressed.

[0037] Moreover, a concave portion 134 is formed on the radially outer outer surface 13D of the magnetic wedge 13. The formation of the concave portion 134 makes it difficult for the interlinking magnetic flux to flow through the magnetic wedge 13. Thereby, it is possible to suppress an increase in the leakage of the interlinking magnetic flux to the magnetic wedge 13.

[0038] <Relationship between the width of the convex portion in the magnetic wedge and the width of the coil, and the occupation ratio of the magnetic wedge> Next, based on FIGS. 6 to 11, the relationship between the width of the convex portion 131 in the magnetic wedge 13 and the width of the coil 12, and the occupation ratio of the magnetic wedge 13 will be described in detail. In the following description, the width of the convex portion 131 is denoted as X, and the width of the innermost surface 12A (see FIG. 2) among the widths of the coil 12 is denoted as Y.

[0039] FIG. 6 is a partially enlarged view of the stator 10 as viewed in the axial direction, and FIGS. 6(a) to 6(c) show the width X of the convex portion 131 and the width Y of the coil 12 being changed. That is, in FIG. 6(a), the widths X and Y satisfy X < Y. This condition is defined as condition (1). In FIG. 6(b), the widths X and Y satisfy X ≈ Y. This condition is defined as condition (2). In FIG. 6(c), the widths X and Y satisfy X > Y. This condition is defined as condition (3). FIG. 6(c) shows a state in which the groove 135 of the magnetic wedge 13 is not formed.

[0040] FIG. 7 is a graph showing the change in torque when the vertical axis represents the torque of the electric motor 1 (hereinafter simply referred to as torque) and the horizontal axis represents the occupation ratio of the magnetic wedge 13, and conditions (1) to (3) are compared. As shown in FIG. 7, it can be confirmed that the torque changes as the occupation ratio of the magnetic wedge 13 changes. Among these, it can be confirmed that in conditions (1) and (2), the decrease in torque can be suppressed compared to condition (3). Also, it can be confirmed that the torque is maximized when the occupation ratio of the magnetic wedge 13 is about 30%.

[0041] FIG. 8 is a graph showing the change in torque ripple when the vertical axis represents the torque ripple of the electric motor 1 (hereinafter simply referred to as torque ripple) and the horizontal axis represents the occupation ratio of the magnetic wedge 13, and conditions (1) to (3) are compared. As shown in FIG. 8, it can be confirmed that the torque ripple changes as the occupation ratio of the magnetic wedge 13 changes. Among these, it can be confirmed that in conditions (1) and (2), the decrease in torque ripple becomes larger compared to condition (3). Also, it can be confirmed that the torque ripple is minimized when the occupation ratio of the magnetic wedge 13 is about 40%.

[0042] FIG. 9 is a graph showing the change in the iron loss of the stator 10 when the vertical axis represents the iron loss of the stator 10 and the horizontal axis represents the occupation ratio of the magnetic wedge 13, and conditions (1) to (3) are compared. As shown in Fig. 9, it can be confirmed that the iron loss of the stator 10 changes as the occupancy rate of the magnetic wedge 13 changes. Among these, it can be confirmed that in conditions (1) and (2), the reduction in iron loss is greater compared to condition (3). Also, it can be confirmed that the iron loss is minimized when the occupancy rate of the magnetic wedge 13 is about 50%.

[0043] Fig. 10 is a diagram showing the analysis results of the iron loss distribution and magnetic flux density distribution in conditions (1) to (3). As shown in Fig. 10, it can be confirmed that in condition (1), the iron loss of the rotor 20 becomes large. Also, it can be confirmed that due to the fact that the interlinking magnetic flux hardly flows through the magnetic wedge 13, the change in the interlinking magnetic flux density between the teeth 110 and the magnetic wedge 13 becomes large.

[0044] On the other hand, in condition (3), it can be confirmed that the interlinking magnetic flux easily flows through the magnetic wedge 13, the iron loss of the stator 10 becomes large, and the change in the interlinking magnetic flux density between the teeth 110 and the magnetic wedge 13 becomes large. As a result of these, it can be confirmed that in condition (2), the iron loss of the rotor 20 and the iron loss of the stator 10 can be reduced. Also, it can be confirmed that the change in the interlinking magnetic flux density between the teeth 110 and the magnetic wedge 13 can be suppressed as much as possible.

[0045] Fig. 11 is a diagram comparing the iron loss density of the stator 10 when a groove 135 is formed in the magnetic wedge 13 (with groove) and when no groove 135 is formed in the magnetic wedge 13 (without groove). As shown in Fig. 11, it can be confirmed that when a groove 135 is formed in the magnetic wedge 13, the iron loss density is high only in the vicinity of the inner peripheral surface 113 of the stator 10. In contrast, when no groove 135 is formed in the magnetic wedge 13, it can be confirmed that the iron loss density is high over the entire teeth 110. As a result, when a groove 135 is formed in the magnetic wedge 13, the interlinking magnetic flux of the teeth 110 can be uniformly dispersed, and the change in the interlinking magnetic flux density between the teeth 110 and the magnetic wedge 13 can be suppressed.

[0046] As described above, in the above-described embodiment, the stator core 11 is formed by laminating a first electromagnetic steel sheet 116 provided with a magnetic wedge 13 and a second electromagnetic steel sheet 117 not provided with a magnetic wedge 13. Therefore, when laminating the first electromagnetic steel sheet 116 and the second electromagnetic steel sheet 117 without changing the shape of the magnetic wedge 13, the occupation ratio of the magnetic wedge 13 can be adjusted only by adjusting their respective ratios. By adjusting the occupation ratio of the magnetic wedge 13, it is possible to easily optimize the magnetic wedge 13 while suppressing a decrease in torque of the electric motor 1 and an increase in iron loss of the stator 10, and reducing torque ripple. Therefore, the processing cost of the stator 10 can be reduced, and ultimately, it can contribute to energy efficiency at a low cost.

[0047] The magnetic wedge 13 includes a convex portion 131 provided on the rotor 20 side. It has a facing surface 13A facing the rotor 20 in the radial direction, and side surfaces 13B extending in a direction away from the rotor 20 from both sides in the circumferential direction on the facing surface 13A. The side surface 13B may be spaced apart from the teeth 110. Therefore, it is possible to smooth the change in the linked magnetic flux density that occurs between the vicinity of the inner peripheral surface 113 of the stator 10 and the vicinity of the radially inner end surface of the magnetic wedge 13. Therefore, it is possible to surely suppress a decrease in torque and an increase in iron loss of the stator 10 while reducing torque ripple.

[0048] The magnetic wedge 13 is integrally formed with the first electromagnetic steel sheet 116. Therefore, the processing cost of the stator 10 can be reduced as compared with the case where the first electromagnetic steel sheet 116 and the magnetic wedge 13 are formed separately. The stator core 11 is formed by alternately laminating the first electromagnetic steel sheet 116 and the second electromagnetic steel sheet 117. Therefore, it is easy to form the stator core 11, and the processing cost of the stator 10 can be further reduced. Also, in the axial direction of the stator core 11, the density distribution of the magnetic wedge 13 becomes uniform. Therefore, it is possible to surely suppress a decrease in torque and an increase in iron loss of the stator 10 while reducing torque ripple.

[0049] The present invention is not limited to the above-described embodiments, and includes those obtained by making various changes to the above-described embodiments without departing from the spirit of the present invention.

[0050] For example, in the above-described embodiment, the case where the magnetic wedge 13 is formed simultaneously when punching out the first electromagnetic steel sheet 116 from the electromagnetic steel sheet serving as the base material and is integrally formed with the first electromagnetic steel sheet 116 has been described. However, the present invention is not limited to this, and the magnetic wedge 13 may be separate from the first electromagnetic steel sheet 116. For example, the first electromagnetic steel sheet 116 and the magnetic wedge 13 are punched out separately from the electromagnetic steel sheet serving as the base material. Thereafter, the first electromagnetic steel sheet 116 and the magnetic wedge 13 may be integrated. By making the magnetic wedge 13 separate from the first electromagnetic steel sheet 116, it is also possible to change the material of the magnetic wedge 13 and the material of the first electromagnetic steel sheet 116.

[0051] In the above-described embodiment, the case where the stator core 11 is formed by alternately laminating the first electromagnetic steel sheet 116 and the second electromagnetic steel sheet 117 has been described. However, the present invention is not limited to this, and the stator core 11 does not necessarily have to be formed by alternately laminating the first electromagnetic steel sheet 116 and the second electromagnetic steel sheet 117. According to the specifications of the electric motor 1, the lamination state of the first electromagnetic steel sheet 116 and the second electromagnetic steel sheet 117 can be appropriately changed. For example, it is also possible to change the occupancy ratio of the magnetic wedge 13 near the center in the axial direction of the stator core 11 and the occupancy ratio of the magnetic wedge 13 near both ends in the axial direction of the stator core 11. Simply changing the ratio of the first electromagnetic steel sheet 116 and the second electromagnetic steel sheet 117 is also possible.

[0052] In the above-described embodiment, the so-called inner rotor type electric motor 1 in which the rotor 20 is arranged inside the stator 10 in the radial direction has been described. However, the present invention is not limited to this, and the configuration using the above-described first electromagnetic steel sheet 116 and second electromagnetic steel sheet 117 can also be applied to a so-called outer rotor type electric motor in which the rotor is provided so as to surround the stator 10.

[0053] In the above-described embodiment, the case where the number of teeth 110 and slots 11S of the electric motor 1 is, for example, 48 each has been described. However, the present invention is not limited to this, and the number of teeth 110 and slots 11S can be arbitrarily determined.

Explanation of Signs

[0054] 1…Electric motor 10…Stator 11…Stator core 11S…Slot 13…Magnetic wedge 13A…Opposite surface 13B…Side surface 20…Rotor 110…Tooth 111…Side surface 116…First electromagnetic steel sheet (first steel sheet) 116T…First tooth steel sheet (tooth) 117…Second electromagnetic steel sheet (second steel sheet) 117T…Second tooth steel sheet (tooth) 131…Convex portion

Claims

1. A stator core having a plurality of teeth arranged in the circumferential direction, and an exciting coil wound around the teeth, wherein the stator core is formed by laminating a first steel plate and a second steel plate, the first steel plate has a magnetic wedge connecting two adjacent teeth in the circumferential direction, the magnetic wedge is disposed between a rotor rotatably provided with respect to the stator core and the coil, the second steel plate has an opening on the rotor side between two adjacent teeth in the circumferential direction, the magnetic wedge has a convex portion provided on the rotor side, the convex portion has a facing surface facing the rotor in the radial direction, and side surfaces extending in a direction away from the rotor from both circumferential sides of the facing surface, the side surfaces are spaced apart from the teeth, when the circumferential width of the facing surface is X and the circumferential width of the coil is Y, the widths X and Y satisfy X < Y and the stator is characterized by this.

2. The magnetic wedge is integrally formed on the first steel plate, and the stator according to claim 1 is characterized by this.

3. The first steel plate and the second steel plate are alternately laminated, and the stator according to claim 1 is characterized by this. ​ ​ ​

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