JP6047946B2 - Field element and rotating electric machine - Google Patents

Description

  The present invention relates to a field element and a rotating electric machine.

  In an IPM (Interior-Permanent-Magnet) motor in which a permanent magnet is provided inside a rotor, a magnet (for example, a ferrite magnet) having a lower residual magnetic flux density than a rare earth magnet can be employed. This is because such a magnet is inexpensive. As such a motor, for example, a motor described in Patent Document 1 can be employed. In Patent Document 1, the magnet is formed in a V-order shape, for example.

  In Patent Document 1, flux barriers are provided on both sides of the magnet in the circumferential direction. This prevents a magnetic short circuit between the magnets.

  Patent documents 2 to 5 are disclosed as techniques related to the present invention.

JP 2010-4777 A JP 2000-50543 A JP 2009-44893 A Japanese Patent Laid-Open No. 11-146484 JP 11-89197 A

  However, in patent documents 1-5, since the shape of the flux barrier is not fully considered from a viewpoint of suppressing demagnetization, it was inadequate also about suppression of demagnetization.

  Therefore, an object of the present invention is to provide a field element that can reduce demagnetization more appropriately.

A first aspect of the field element according to the present invention is provided with a plurality of permanent magnets that are provided side by side in the circumferential direction around the rotation axis (P) and that alternately have different magnetic poles on the opposite side of the rotation axis. 2), a field element core (1) in which the permanent magnet is embedded, and a nonmagnetic material (3) provided in the field element core, the field element being parallel to the rotation axis Each of the permanent magnets as viewed from the axial direction has a shape that protrudes toward the rotating shaft, and a pair of magnet side surfaces (23) having a flat portion at the end in the circumferential direction, and the rotating shaft The first magnet surface (21) and the second magnet surface (22) which are located on the opposite side and the rotating shaft side and are connected to each other by the magnet side surfaces, and the non-magnetic material ( 3) extends from the magnet side surface of one of the permanent magnets toward the outer peripheral surface of the field element core, The first non-magnetic surface (31) and the second non-magnetic surface (32), which are respectively located on the inter-polar side and form the outer edge of the non-magnetic material, and when viewed from the axial direction, The minimum distance (b1) between the first corner (2b) formed by the magnet side surface (23) and the second magnet surface (22) and the first nonmagnetic surface (31) is It is not less than the end distance (a) between the one corner (2b) and the second corner (2a) formed by the one magnet side surface and the first magnet surface (21) , and (ii) the second minimum distance between the second corner and the non-magnetic surface (32) (2a) (b2 ) is at said end distance (a) above, (iii) the non-magnetic member before distichum A minimum width (c) in the direction is smaller than a minimum width (a ′) of the one permanent magnet on the non-magnetic material side.

A second aspect of the field element according to the present invention is the field element according to the first aspect, wherein the first nonmagnetic surface (31) has a curved shape that swells toward the pole center.

  A third aspect of the field element according to the present invention is the field element according to the first or second aspect, wherein the second nonmagnetic surface (32) approaches the outer peripheral surface as It approaches the pole center in the circumferential direction.

  A field element according to a fourth aspect of the present invention is a field element according to any one of the first to third aspects, wherein the permanent magnet (2) and the non-magnetic body (3) are It is integrally formed by two-color molding.

According to a first state like according field element of the present invention, it is possible to reduce the demagnetization flux passing through the ends of the permanent magnets of the first corner and the second corner side. Therefore, the demagnetization resistance of the permanent magnet can be improved.

  According to the 2nd aspect of the field element concerning this invention, since a corner | angular part does not arise in a curved shape, stress can be reduced.

  According to the third aspect of the field element of the present invention, it is possible to increase the magnetic path width between the permanent magnets in the first circumferential direction (the interval between the nonmagnetic materials in the first circumferential direction). The q-axis inductance due to the magnetic path can be increased.

  According to the 4th aspect of the field element concerning this invention, since a permanent magnet and a nonmagnetic material are united, the movement (vibration) in the circumferential direction of a permanent magnet can be suppressed.

It is a figure which shows an example of a notional structure of the field element seen along the rotating shaft. It is a figure which shows an example of a conceptual structure of a part of field element seen along the rotating shaft. It is a figure which shows an example of a conceptual structure of a part of field element seen along the rotating shaft. It is a figure which shows an example of a conceptual structure of a part of field element seen along the rotating shaft. It is a figure which shows an example of a conceptual structure of a part of field element seen along the rotating shaft. It is a figure which shows an example of a conceptual structure of a part of field element seen along the rotating shaft. It is a figure which shows an example of a conceptual structure of a part of field element seen along the rotating shaft. It is a figure which shows an example of a conceptual structure of a part of field element seen along the rotating shaft. It is a figure which shows an example of a notional structure of the field element seen along the rotating shaft. It is a figure which shows an example of a conceptual structure of a part of field element seen along the rotating shaft. It is a figure which shows an example of a conceptual structure of a part of field element seen along the rotating shaft. It is a figure which shows an example of a conceptual structure of a part of field element seen along the rotating shaft. It is a figure which shows an example of some conceptual structures of the rotary electric machine seen along the rotating shaft.

First embodiment.
As illustrated in FIG. 1, the field element 5 includes a field element core 1, a plurality of permanent magnets 2, and a nonmagnetic material 3. Hereinafter, the circumferential direction and the radial direction around the rotation axis P are simply referred to as the circumferential direction and the radial direction, respectively, and the direction parallel to the rotation axis P is referred to as the axial direction.

  The permanent magnets 2 are arranged side by side along the circumferential direction. Two of these permanent magnets 2 adjacent to each other in the circumferential direction are provided with magnetic pole surfaces having different polarities facing away from the rotation axis P. In other words, the plurality of permanent magnets 2 present magnetic poles alternately different in the circumferential direction on the side opposite to the rotation axis P. For example, the upper right and lower right permanent magnets 2 on the plane of the paper present N poles on the side opposite to the rotation axis P, and the upper left and lower left permanent magnets 2 on the side of the page exhibit S poles on the side opposite to the rotation axis P.

  Each permanent magnet 2 has a shape that protrudes toward the rotation axis P. In the illustration of FIG. 1, each permanent magnet 2 has a shape along an arc centered on a center point Q located on the opposite side of the rotation axis P with respect to itself, for example. Such a shape is also called a reverse arc shape in the sense that it is different from an arc centered on the rotation axis P. In the following, the circumferential direction around the center point Q that defines the shape of a certain magnet is called the magnet circumferential direction for the magnet, and the radial direction around the center point Q is called the magnet radial direction for the magnet.

  In such a shape, the permanent magnet 2 has a pair of magnet side surfaces 23 and magnet surfaces 21 and 22. The magnet side surfaces 23 have flat portions at both ends in the circumferential direction of the permanent magnet 2. The magnet surfaces 21 and 22 are located on the side opposite to the rotation axis P and on the rotation axis P side, and are connected to each other by the magnet side surface 23. It can also be expressed that the magnet surface 21 is located on the center point Q side and the magnet surface 22 is located on the opposite side of the center point Q. A magnetic pole surface as the permanent magnet 2 is formed on the magnet surfaces 21 and 22.

  In the illustration of FIG. 1, four permanent magnets 2 are provided. That is, a 4-pole field element is shown. However, the present invention is not limited to this, and the number of poles of the field element may be any even number. In the illustration of FIG. 1, each of the permanent magnets 2 forms one magnetic pole, but one magnetic pole may be formed by a plurality of permanent magnets. In other words, each of the permanent magnets 2 may be divided into a plurality of permanent magnets.

  The field element core 1 is formed of, for example, a soft magnetic material (for example, iron) and has, for example, a cylindrical shape with the rotation axis P as the center. The above-described permanent magnet 2 is embedded in the field element core 1. For example, the field element core 1 is provided with a storage hole, and the permanent magnet 2 is stored in the storage hole. By storing the permanent magnet 2, magnetic pole faces that are alternately different in the circumferential direction are formed on the outer circumferential face 10 of the field element core 1.

  In the illustration of FIG. 1, the field element core 1 is provided with a shaft insertion hole 11 in a region including the rotation axis P. A shaft (not shown) is inserted into the shaft insertion hole 11. The shaft and the field element core 1 are fixed to each other, for example, by press fitting. The shaft insertion hole 11 is not an essential requirement. For example, when end plates are provided at both ends of the field element 5 in the axial direction along the rotation axis P and a shaft is attached to the end plates, the shaft insertion hole 11 is not necessary.

  More specifically, a rotating electric machine can be realized by disposing an armature (not shown) with respect to such a field element 5 so as to face the outer peripheral surface via an air gap. . The armature applies a rotating magnetic field to the field element, and the armature and the field element rotate relatively in accordance with the rotating magnetic field. In the illustration of FIG. 1, the field element functions as a rotor.

  The non-magnetic body 3 is provided in the field element core 1 and extends from the magnet side surface 23 side of the permanent magnet 2 toward the outer peripheral surface 10 of the field element core 1. For example, the nonmagnetic material 3 is provided at a position facing the magnet side surface 23 of the one permanent magnet 2 in the magnet circumferential direction of the one permanent magnet 2. By this nonmagnetic material 3, it is possible to suppress a magnetic short circuit between the permanent magnets 2 adjacent in the circumferential direction and a magnetic short circuit between the magnet surfaces 21 and 22 in one permanent magnet 2.

  Such a nonmagnetic material 3 is stored in, for example, a nonmagnetic storage hole formed in the field element core 1. The nonmagnetic material 3 may be any nonmagnetic material, for example, air. When the nonmagnetic material 3 is air, the nonmagnetic storage hole itself corresponds to the nonmagnetic material 3.

  In the illustration of FIG. 1, there is a connecting portion 15 as a part of the field element core 1 on the outer peripheral side of the nonmagnetic material 3. The connecting portion 15 connects the core on the outer peripheral side and the core on the inner peripheral side with respect to the permanent magnet 2 and the nonmagnetic body 3. As a result, the strength of the field element core 1 can be improved. The connecting portion 15 is preferably formed of a thin portion having a thin radial width around the rotation axis P. In other words, it is desirable that the connecting portion 15 be formed of a thin portion that is easily magnetically saturated. As a result, the permanent magnet 2 can be prevented from being magnetically short-circuited via the connecting portion 15.

  In the illustration of FIG. 1, the non-magnetic body 3 and the permanent magnet 2 are in contact with each other, but they may be separated from each other in the magnet circumferential direction. For example, a part of the field element core 1 may be interposed between the nonmagnetic material 3 and the permanent magnet 2. As a result, the strength of the field element core 1 can be improved. In addition, it is desirable that this part is formed by a thin portion that has a small width in the circumferential direction of the magnet and is easily saturated with the magnet. This can prevent a short circuit through the part of the magnet surfaces 21 and 22.

  Hereinafter, with reference to FIG. 2, the shape of the nonmagnetic material 3 in a cross section perpendicular to the rotation axis P will be described in detail. In the illustration of FIG. 2, only the region corresponding to one of the nonmagnetic bodies 3 in the field element 5 is shown for ease of illustration. In other drawings, only the relevant part is shown as appropriate.

  Here, the nonmagnetic surfaces 31 and 32 that form the outer edge of the nonmagnetic material 3 will be particularly described. The nonmagnetic surface 31 is a surface located on the pole center side of the nonmagnetic material 3, and the nonmagnetic surface 32 is a surface located on the interpolar side of the nonmagnetic material 3. The pole center here is the center in the circumferential direction of the magnetic pole of the field element core 1 formed by the permanent magnet 2 corresponding to the non-magnetic body 3. Further, the distance between the poles is an end in the circumferential direction of the magnetic pole (that is, a boundary between the magnetic pole and a magnetic pole adjacent to the magnetic pole in the circumferential direction).

  Hereinafter, a corner formed by the magnet surface 21 and the magnet side surface 23 is referred to as a corner 2a, and a corner formed by the magnet surface 22 and the magnet side surface 23 is referred to as a corner 2b.

  The nonmagnetic material 3 satisfies the following three relationships. First, the minimum distance b1 between the nonmagnetic surface 31 and the corner 2b is equal to or greater than the distance between the corners 2a and 2b (hereinafter referred to as end distance) a. In other words, the nonmagnetic surface 31 is provided closer to the pole center side (center point Q side) than the virtual arc R1 having the corner portion 2b as the center and the end portion distance a as the radius. However, the nonmagnetic surface 31 may circumscribe the virtual arc R1 and may have the same shape as the virtual arc R1.

  In the illustration of FIG. 2, the nonmagnetic surface 31 has, for example, surfaces 311 and 312. For example, the surface 312 extends from the magnet surface 21 toward the outer peripheral surface 10 and has a shape along an arc centered on the center point Q (see FIG. 1). The surface 311 has, for example, a linear shape, and extends from one end of the surface 312 opposite to the permanent magnet 2 toward the outer peripheral surface 10. In the illustration of FIG. 2, the surface 311 circumscribes the virtual arc R1. Therefore, the minimum distance b1 is a distance between the contact point and the corner 2b, and the value is equal to the end distance a.

  Second, the minimum distance b2 between the nonmagnetic surface 32 and the corner 2a is equal to or greater than the end distance a. In other words, the nonmagnetic surface 32 is provided on the side closer to the pole (the side opposite to the center point Q) than the virtual arc R2 having the corner 2a as the center and the end distance a as the radius. However, the nonmagnetic surface 32 may circumscribe the virtual arc R2 or may have the same shape as the virtual arc R2.

  In the illustration of FIG. 2, the nonmagnetic surface 32 extends from the magnet surface 22 toward the outer peripheral surface 10 and has a shape along an arc centered on the center point Q. Therefore, the minimum distance b2 is the distance between the corners 2a and 2b, and its value is equal to the end distance a.

  In the illustration of FIG. 2, the nonmagnetic surfaces 31 and 32 are connected to each other via the nonmagnetic surface 33 on the outer peripheral surface 10 side. The nonmagnetic surface 33 is located on the outer peripheral surface 10 side with respect to the virtual arcs R1 and R2.

  Third, the minimum width c in the circumferential direction of the nonmagnetic body 3 (the minimum distance between the nonmagnetic surfaces 31 and 32 in the circumferential direction) is smaller than the minimum width a ′ of the permanent magnet 2 on the magnet side surface 23 side.

  In the illustration of FIG. 2, the minimum width a 'of the permanent magnet 2 is equal to the end distance a. On the other hand, in the illustration of FIG. 3, the end distance a is longer than the minimum width a '. In the illustration of FIG. 2, the magnet side surface 23 has a flat shape along the magnet radial direction (see also FIG. 1), whereas in the illustration of FIG. 3, the magnet side surface 23 does not follow the magnet radial direction. It is because it has a flat shape.

  2 and 3, the width in the circumferential direction between the surface 311 and the nonmagnetic surface 32 decreases monotonously as the outer peripheral surface 10 is approached. In other words, the nonmagnetic material 3 has a tapered shape that narrows toward the outer peripheral surface 10. 2 and 3, the width in the circumferential direction of the nonmagnetic material 3 takes the minimum value c on the outer peripheral surface 10 side.

  According to such a nonmagnetic material 3, the demagnetization resistance at the end of the permanent magnet 2 can be improved. This will be described in detail below.

  As indicated by a thick arrow in FIG. 4, a part of the reverse magnetic field can be applied to the corner 2 b of the permanent magnet 2 through the nonmagnetic body 3 between the corner 2 b and the nonmagnetic surface 31. Note that the reverse magnetic field here is a magnetic field that generates a magnetic flux in a direction opposite to the magnetic flux generated from the permanent magnet 2, and is generated by an armature (not shown). Since the magnetic flux due to such a reverse magnetic field causes demagnetization of the permanent magnet 2, this magnetic flux is hereinafter referred to as a demagnetizing magnetic flux.

  According to the present embodiment, since the minimum distance b1 is equal to or greater than the end portion distance a, for example, the nonmagnetic body 3 ′ in FIG. 4 (the minimum distance b1 is less than the end portion distance a in the nonmagnetic body 3 ′). As compared with this, the reverse magnetic field applied to the corner 2b can be reduced. In other words, the demagnetizing magnetic flux flowing through the end of the permanent magnet 2 on the corner 2b side can be reduced. This is because by setting the minimum distance b1 between the nonmagnetic surface 31 and the corner 2b to be equal to or greater than the end distance a, the magnetic resistance in the path passing through the end of the permanent magnet 2 on the corner 2b side can be increased. Because it can. Further, since the minimum distance b1 is equal to or greater than the end distance a, the demagnetization resistance of the permanent magnet 2 against the demagnetizing magnetic flux going to the corner portion 2b via the non-magnetic body 3 is reduced to the corner portion via the corner portion 2a. The demagnetization resistance of the permanent magnet 2 with respect to the demagnetizing magnetic flux toward 2b can be set to the same level or more.

  Further, since the minimum width c is narrower than the minimum width a ′, the demagnetizing magnetic flux tends to flow to the portion having the minimum width c in the nonmagnetic material 3 rather than the permanent magnet 2. This is because the magnetic permeability of the permanent magnet 2 is very small, so that the magnetic resistance can be regarded as the same as the non-magnetic material 3, and since the minimum width c is narrower than the minimum width a ′, this part is preferentially given over the permanent magnet 2. The demagnetizing magnetic flux flows to the side. Therefore, demagnetization at other locations of the permanent magnet 2 is also less likely to occur.

  Furthermore, according to the nonmagnetic material 3, the minimum distance b2 is also larger than the end portion distance a. Therefore, unlike the illustration of FIG. 4, the demagnetizing magnetic flux that flows from the outer peripheral surface 10 side between the poles to the corner portion 2a through the nonmagnetic material 3 (the broken line demagnetization flowing from the upper left to the lower right in FIG. 4). Magnetic flux) can also be reduced. Therefore, the demagnetization of not only the corner portion 2b of the permanent magnet 2 but also the corner portion 2a can be suppressed against such a demagnetizing magnetic flux.

  Here, the distance between the corner 2b and the nonmagnetic surface 31 is considered as the magnetic resistance for the corner 2b, and the distance between the corner 2a and the nonmagnetic surface 32 is considered as the magnetic resistance for the corner 2a. did. On the other hand, it is not necessary to consider the distance between the corner 2b and the nonmagnetic surface 32. Similarly, it is not necessary to consider the distance between the corner 2a and the nonmagnetic surface 31. This is because, for example, even if there is a demagnetizing magnetic flux flowing from the outer peripheral surface 10 to the nonmagnetic surface 32 side, this demagnetizing magnetic flux flows in the circumferential direction without going to the corner portion 2b (see FIG. 4). . Therefore, it is almost unnecessary to consider the distance between the corner 2b and the nonmagnetic surface 32 as the magnetic resistance of the corner 2b. The same applies to the distance between the corner 2a and the nonmagnetic surface 31.

  It has been confirmed by the applicant that the use of such a nonmagnetic material 3 can improve the demagnetization proof strength by 10 to 20% compared to the conventional case (for example, nonmagnetic material 3 ').

  2 and 3, the nonmagnetic surface 31 of the nonmagnetic body 3 approaches the gap as it approaches the outer peripheral surface 10. According to this shape, it is possible to widen the q-axis magnetic path on the outer peripheral surface 10 side of the permanent magnet 2 in the field element core 1.

<Corner>
1-4, the magnet side surface 23 forms an angle with the magnet surfaces 21 and 22, respectively. However, in actual manufacturing, for example, roundness and chamfering are formed without forming a precise corner.

  In the illustration of FIG. 5, the permanent magnet 2 is rounded at the end. In such a shape, the corners 2a and 2b are grasped as follows. That is, the corner 2 b is a corner formed by a virtual line extending from the magnet surface 22 and a virtual line along the flat portion of the magnet side surface 23. The imaginary line obtained by extending the magnet surface 22 is, for example, a phantom line obtained by extending the magnet surface 22 to the outer peripheral surface 10 while maintaining its curvature. The corner portion 2 a is a corner portion formed by an imaginary line extending from the magnet surface 21 and an imaginary line along the flat portion of the magnet side surface 23. The same applies to a virtual line obtained by extending the magnet surface 21.

  In the illustration of FIG. 6, the permanent magnet 2 is chamfered at its end. Specifically, the side surface 23 is bent on the surfaces 21 and 22 side. Even in such a shape, the corners 2a and 2b are grasped as described with reference to FIG.

<Non-magnetic material>
The nonmagnetic body 3 illustrated in FIG. 7 is different from the nonmagnetic body 3 of FIG. The nonmagnetic surface 31 in FIG. 7 has a curved shape that swells toward the pole center. Thereby, for example, the corners formed by the nonmagnetic surfaces 31 and 33 can be formed at a more obtuse angle. Therefore, the stress generated in the corner can be relaxed. Further, since no corners are generated on the nonmagnetic surface 31 itself, the concentration of stress generated on the nonmagnetic surface 31 can be suppressed.

  The nonmagnetic material 3 illustrated in FIG. 8 is different from the nonmagnetic material 3 of FIG. The nonmagnetic surface 31 in FIG. 8 has a step shape formed by a plurality of flat portions. In this stepped shape, the width in the circumferential direction of the nonmagnetic material 3 decreases as the outer peripheral surface 10 is approached. More specifically, the nonmagnetic surface 31 has surfaces 313 to 315. The surface 313 extends from one end on the pole center side of the nonmagnetic surface 33 toward the permanent magnet 2 along the circumferential direction of the magnet, and is connected to the surface 314. The surface 314 extends from the end (on the opposite side of the nonmagnetic surface 33) of the surface 313 to the pole center side along the circumferential direction and is connected to the surface 315. Surface 315 extends from the end of surface 314 (on the opposite side to surface 313) to magnet surface 21 and follows the same arc as the arc along magnet surface 21. In this way, a step shape is formed by the surfaces 313 to 315.

  The nonmagnetic body 3 illustrated in FIG. 9 is different from the nonmagnetic body 3 of FIG. The nonmagnetic surface 32 of FIG. 9 approaches the pole center side in the circumferential direction as it approaches the outer peripheral surface 10. In the illustration of FIG. 9, the nonmagnetic surface 32 is located on the pole center side with respect to the virtual arc R <b> 3 along the magnet surface 22. That is, in the illustration of FIG. 1, the nonmagnetic surface 32 extends so as to follow the arc of the magnet surface 22, and the nonmagnetic surface 31 is inclined toward the pole side with respect to the arc of the magnet surface 21, thereby forming a tapered shape. In contrast to the above, in the example of FIG. 9, the nonmagnetic surface 32 is also inclined toward the pole center side to form a tapered shape.

  Thereby, the width in the circumferential direction between the non-magnetic bodies 3 is increased on the outer peripheral surface 10 side. Therefore, the q-axis magnetic path between the poles can be increased. As a result, the q-axis inductance can be improved, and the reluctance torque can be improved.

  The nonmagnetic material 3 illustrated in FIG. 10 is air. Compared with the nonmagnetic body 3 in FIG. 1, the nonmagnetic body 3 in FIG. 10 (that is, a hole formed in the field element core 1) opens radially outward on the outer peripheral surface 10. Further, a connecting portion 14 as a part of the field element core 1 is interposed between the non-magnetic body 3 and the permanent magnet 2. By the connecting portion 14, the core on the outer peripheral side and the core on the inner peripheral side than the permanent magnet 2 are connected to each other. The connecting portion 14 is formed by a thin portion having a thin width in the magnet circumferential direction. In other words, the connecting portion 14 is formed by a thin portion that is easily magnetically saturated. Thereby, a magnetic short circuit of the permanent magnet 2 through the connecting portion 14 can be suppressed.

  The nonmagnetic material 3 is not limited to air but may be solid. In this case, the nonmagnetic material 3 is exposed on the outer peripheral surface 10.

  Since all of the nonmagnetic bodies 3 in FIGS. 7 to 10 satisfy the first to third relationships, the demagnetization resistance at the end of the permanent magnet 2 can be improved even with these nonmagnetic bodies 3. Can do.

  1 to 10 has a tapered shape in which the width in the circumferential direction becomes narrower toward the outer peripheral surface 10 side, but is not limited thereto. For example, the width in the circumferential direction of the non-magnetic body 3 may be reduced once as it goes from the permanent magnet 2 to the outer peripheral surface 10, and may be increased after taking the minimum value. That is, for example, a shape like an internal space of an hourglass may be adopted.

<Fixing in the circumferential direction of the permanent magnet 2>
For example, in the illustration of FIG. 2, the nonmagnetic surface 32 has a surface 312 that follows the arc of the magnet surface 21. This is advantageous from the viewpoint that the minimum distance b1 is not less than the end distance a. That is, unlike the present embodiment, when the nonmagnetic surface 31 is connected in a straight line from the corner 2a to the nonmagnetic surface 33 as in the nonmagnetic material 3 ', the minimum distance b1 is shorter than the end distance a. (See FIG. 4). On the other hand, in the present embodiment, the minimum distance in this portion is more reliably set to the end distance a or more by the surface 312. Similarly, in the illustration of FIG. 2, the nonmagnetic surface 32 is along the same arc as the arc along the magnet surface 22. As a result, the minimum distance b1 between the corner 2b and the nonmagnetic surface 32 is more reliably set to the end distance a or more.

  However, since both of the minimum distances b1 and b2 are longer than the end portion distance a, the width of the nonmagnetic body 3 on the permanent magnet 2 side can be wider than the width of the permanent magnet 2. In this case, if the nonmagnetic material 3 is formed of air, the permanent magnet 2 can move in the magnet circumferential direction. Such movement of the permanent magnet 2 is not preferable in terms of performance of the rotating electrical machine. Therefore, in this case, it is desirable to provide a fixing portion for fixing the position of the permanent magnet 2 in the circumferential direction.

  Such a fixing part can be realized by various fixings, and arbitrary fixing is employed without departing from the gist of the present embodiment. For example, the fixed portion may include a protrusion or recess provided on the magnet surface 21 or the magnet surface 22 and a recess or protrusion provided on the field element core 1 by fitting with the protrusion or recess. As a result, the circumferential position of the permanent magnet 2 is fixed.

  Further, as shown in FIG. 11, the fixed portion may be a protrusion 16 provided on the field element core 1. The protrusion 16 is provided at a position facing the magnet side surface 23 in the magnet circumferential direction, and hinders movement of the permanent magnet 2 in the magnet circumferential direction. The protrusion 16 is formed by a thin portion having a small width in the magnet circumferential direction. In other words, the protrusion 16 is formed by a thin portion that is easily magnetically saturated. Such protrusions 16 can be considered magnetically non-magnetic. Therefore, the protrusion 16 can be regarded as a part of the nonmagnetic material 3.

  Moreover, it replaces with the protrusion 16 and the connection part 14 of FIG. 10 may be provided as a fixing | fixed part. This can also prevent the movement of the permanent magnet 2.

  Moreover, when providing an end plate on both sides of the field element 5 in the axial direction, a fixing portion may be provided on the end plate. For example, a rod-like protrusion extending in the axial direction is provided on the end plate, and this protrusion is inserted into the nonmagnetic material 3. Referring to FIG. 12, the protrusion 4 faces the magnet side surface 23 in the magnet circumferential direction with the end plate attached to the field element. This prevents the permanent magnet 2 from moving in the circumferential direction of the magnet. In addition, it is desirable that the protrusion 4 is provided non-magnetically. Alternatively, the protrusion 4 is preferably formed by a thin portion having a thin width in the magnet radial direction or the magnet circumferential direction. In other words, it is desirable that the protrusion is formed by a thin portion that is easily magnetically saturated. Thereby, it is possible to prevent the permanent magnet 2 from being magnetically short-circuited through the protrusion 4 and the end plate.

<Two-color molding>
The non-magnetic material 3 and the permanent magnet 2 may be molded in two colors. For example, the non-magnetic material 3 is molded from a resin, and the permanent magnet 2 is molded from a bonded magnet. More specifically, for example, first, a bonded magnet is formed by injecting a mixture of a hard magnetic piece and a resin into a mold having a space corresponding to the permanent magnet 2 and performing injection molding. Subsequently, for example, the upper mold is replaced to form a space corresponding to the non-magnetic material 3, and the resin is injected into this space for molding. Thereby, the nonmagnetic material 3 and the permanent magnet 2 can be integrally formed. Thereby, the movement (vibration) in the circumferential direction of the permanent magnet 2 can be suppressed. The molding order of the permanent magnet 2 and the nonmagnetic material 3 is arbitrary.

  Moreover, you may combine shaping | molding of the core 1 for field elements, the permanent magnet 2, and the nonmagnetic body 3. FIG. For example, after the field element core 1 is formed by compression molding, the permanent magnet 2 and the nonmagnetic material 3 may be sequentially formed by injection molding. As a result, the non-magnetic material 3, the permanent magnet 2, and the field element core 1 can be integrally formed. In this case, the field element core 1 is formed of a dust core. In addition, what is necessary is just to shape | mold at least two of the core 1 for field elements, the permanent magnet 2, and the nonmagnetic body 3, and a shaping | molding order is arbitrary.

  In addition, although the reverse arc shape was illustrated as a shape of the permanent magnet 2, it is not restricted to this. For example, the permanent magnet 2 may have a V-shape that protrudes toward the rotation axis P.

Second embodiment.
In the first embodiment, focusing on the field element 5 alone, the demagnetization resistance at the end of the permanent magnet 2 is improved. Here, attention is paid to a rotating electric machine having a field element 5 and an armature 6.

  As illustrated in FIG. 13, the armature 6 faces the field element 5 through the air gap in the radial direction. In FIG. 13, only one tooth of the armature 6 is illustrated. Actually, the armature 6 includes a plurality of teeth, a back yoke, and a winding. The plurality of teeth are arranged radially about the rotation axis P (see FIG. 1 and the like). The back yoke magnetically connects one end of the plurality of teeth opposite to the field element 5. The winding is wound around the teeth by, for example, concentrated winding.

  A reverse magnetic field applied to the permanent magnet 2 is generated by the armature 6. Therefore, as illustrated in FIG. 13, not only the nonmagnetic body 3 but also the nonmagnetic air gap g is interposed in the path of the demagnetizing magnetic flux passing through the end of the permanent magnet 2 on the corner 2 b side. Therefore, the sum of the minimum distance b1 and the air gap g can be regarded as the magnetoresistance in this path.

  Therefore, the sum of the minimum distance b1 and the air gap g may be equal to or greater than the end distance a, and similarly, the sum of the minimum distance b2 and the air gap g may be equal to or greater than the end distance a. Similarly to the first embodiment, the minimum width c between the nonmagnetic surfaces 31 and 32 in the circumferential direction is smaller than the minimum width a 'between the magnet surfaces 21 and 22 on the nonmagnetic body 3 side.

  Such a nonmagnetic material 3 can also improve the demagnetization resistance of the end of the permanent magnet 2. Note that the specific shape of the nonmagnetic material 3 is the same as that of the first embodiment, so that repeated description is avoided.

DESCRIPTION OF SYMBOLS 1 Core for field element 2 Permanent magnet 3 Non-magnetic material 21, 22 Magnet surface 23 Magnet side surface 31, 32 Non-magnetic surface a End distance a 'Minimum width b1, b2 Minimum distance c Minimum width P Rotating shaft

Claims (4)

A plurality of permanent magnets (2) provided side by side in the circumferential direction around the rotation axis (P) and presenting different magnetic poles alternately on the opposite side of the rotation axis,
A field element core (1) in which the permanent magnet is embedded;
A field element comprising a non-magnetic material (3) provided in the field element core,
Each of the permanent magnets when viewed from an axial direction parallel to the rotation axis,
Having a shape that protrudes toward the rotating shaft;
A pair of magnet side surfaces (23) having a flat portion at the circumferential end, and
A first magnet surface (21) and a second magnet surface (22) which are respectively located on the opposite side of the rotating shaft and on the rotating shaft side and connected to each other by the magnet side surfaces;
The non-magnetic material (3) viewed from the axial direction is
Extending from one magnet side surface of one of the permanent magnets toward the outer peripheral surface of the field element core,
A first non-magnetic surface (31) and a second non-magnetic surface (32) which are located on the pole center side and the pole-pole side of the magnetic pole and form the outer edge of the non-magnetic material, respectively.
Have
Seen from the axial direction,
(i) The minimum distance (b1) between the first corner (2b) formed by the one magnet side surface (23) and the second magnet surface (22) and the first nonmagnetic surface (31) ) Is equal to or greater than the end distance (a) between the first corner (2b) and the second corner (2a) formed by the one magnet side surface and the first magnet surface (21). Yes,
(ii) The minimum distance (b2) between the second nonmagnetic surface (32) and the second corner (2a) is not less than the end distance (a);
(iii) the minimum width in the front distichum direction of the non-magnetic material (c), the smaller than the one of the minimum width of the permanent magnet in the non-magnetic side (a '),
A field element that has the relationship The field element according to claim 1, wherein the first nonmagnetic surface has a curved shape that swells toward the pole center.   The field element according to claim 1 or 2, wherein the second nonmagnetic surface (32) approaches the pole center in the circumferential direction as the outer peripheral surface is approached.   The field element according to any one of claims 1 to 3, wherein the permanent magnet (2) and the non-magnetic body (3) are integrally formed by two-color molding.

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