Rotating electric machine field element

Abstract

To provide a field element that is able to achieve both prevention of magnetic flux leakage and suppression of reduction in magnet holding force.SOLUTION: A field element (4) of a rotary electric machine (1) includes: a plurality of magnets 14 arranged in a predetermined array in an annular shape around an axis 2; and a yoke 13 provided along an inner peripheral surface 14c of the magnets 14. The yoke 13 includes: a cylindrical main body portion 26 extending in an axial direction from a first end- face 14a of the magnets 14 in the axial direction to a second end-face 14b in the axial direction; and an annular flange portion 27 extending in a radial direction from the main body portion 26 and including a contact face 28 that is in contact with the first end-face 14a of the magnets 14. The contact face 28 has at least one of a circumferential groove 36 formed in an annular shape at an intermediate position separated from a base-end edge 28a and a tip-end edge 28b in the radial direction and a plurality of radial grooves 37 arranged at predetermined intervals P in the circumferential direction and extending from the base-end edge 28a to the tip-end edge 28b.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a field element for a rotating electric machine. [Background technology]

[0002] A rotating electric machine includes an armature having teeth and a coil, and a field element having a magnet and a back yoke, one of which constitutes a rotor that rotates around a rotation axis, and the other of which constitutes a stator. In a radial gap type rotating electric machine, the magnet and teeth are arranged so as to face each other in the radial direction of the rotating electric machine. A well-known rotating electric machine of this type is an outer rotor type radial gap type rotating electric machine in which the field element forms the outer rotor. In this rotating electric machine, a back yoke is arranged along the magnetic pole face on the radial outside of the magnet.

[0003] Patent Document 1 discloses a rotating electric machine in which a back yoke is provided spanning from the radially outer magnetic pole face of the magnet to both axial end faces of the magnet, and the end of the radially inner part of the back yoke (the part along both end faces of the magnet; hereinafter referred to as the flange part) is provided away from the magnet. According to this, there is an air gap between the radially inner magnetic pole face of the magnet and the end of the back yoke (the tip of the flange part), so magnetic flux leakage is reduced. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-093950 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned conventional field element, the tip of the flange portion of the back yoke is separated from the magnet, so the area of ​​the flange portion that abuts against the end face of the magnet to restrict magnet movement is reduced. As a result, there is a risk of a decrease in the magnet holding force of the back yoke. Therefore, there is a need for a field element structure that can simultaneously prevent magnetic flux leakage and suppress a decrease in magnet holding force.

[0006] In view of the above background, an object of the present invention is to provide a field element that can simultaneously prevent magnetic flux leakage and suppress a decrease in magnetic holding force. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, one aspect of the present invention is a field element (4) for a rotating electric machine (1, 51), comprising: a plurality of magnets (14) arranged in a predetermined arrangement in an annular shape around an axis (2) of the rotating electric machine; and a yoke (13) provided along one of an inner peripheral surface (14c) and an outer peripheral surface (14d) of the magnets, the yoke being a cylindrical member extending in the axial direction from a first end face (14a) in the axial direction of the magnets to a second end face (14b) in the axial direction. and an annular flange portion (27) extending radially from the main body portion and having an abutment surface (28) that abuts against the first end surface of the magnet, the abutment surface having at least one of an annular circumferential groove (36) formed at an intermediate position spaced apart from a radial base edge (28a) and a radial tip edge (28b) of the abutment surface, and a plurality of radial grooves (37) formed at a predetermined interval (P) around the abutment surface and extending from the base edge to the tip edge.

[0008] According to this aspect, the tip of the flange at least partially abuts against the first end face of the magnet, thereby improving the magnet's holding force compared to a conventional structure in which an annular gap is provided at the tip of the flange. Furthermore, by providing at least one of a circumferential groove and a plurality of radial grooves on the abutment surface, leakage of magnetic flux to the outside through the flange is suppressed. Therefore, the output torque of an electric motor using this field element or the power generation efficiency of a generator is improved.

[0009] In the above aspect, the contact surface may have both the circumferential groove and a plurality of the radial grooves.

[0010] According to this aspect, by providing both the circumferential groove and the plurality of radial grooves on the contact surface, leakage of magnetic flux to the outside through the flange portion is further suppressed.

[0011] In the above aspect, the predetermined arrangement may be a Halbach arrangement in which a third magnet (33) having a magnetic pole direction including a circumferential component is arranged between a first magnet (31) having a magnetic pole direction facing radially inward and a second magnet (32) having a magnetic pole direction facing radially outward.

[0012] According to this aspect, in a Halbach array field element including the magnetic pole direction in the circumferential direction, it is possible to prevent magnetic flux leakage and suppress a decrease in the magnetic holding force.

[0013] In the above aspect, it is preferable that the plurality of radial grooves are arranged at regular intervals in the circumferential direction, and that the regular intervals are smaller than the circumferential width (C) of the third magnet.

[0014] According to this aspect, at least one radial groove is disposed in the portion of the abutment surface corresponding to the third magnet, and therefore the radial groove effectively prevents the circumferential magnetic flux of the third magnet from leaking to the outside through the flange portion.

[0015] In the above aspect, it is preferable that a circumferential dimension (D) of an abutting portion (38) between a pair of the radial grooves adjacent to each other in the circumferential direction is larger than a width (W) of the radial grooves.

[0016] According to this embodiment, the contact area of ​​the flange portion that actually contacts the magnet is increased, which makes it possible to reliably position the three types of magnets that have strong magnetic repulsion.

[0017] In the above aspect, when viewed in the axial direction, the area (A 31 ) and the area of ​​the second magnet (A32 ) are the same as each other, and the area (A 37 ) the area (A 36 ) is the groove area ratio (A 36 / A 37 ) is the area (A 33 ) to the area (A 31 ) is the magnet area ratio (A 31 / A 33 ) should be the same as

[0018] According to this aspect, the magnetic resistance of the magnetic flux passing through both the circumferential groove and the radial groove is increased, and magnetic flux leakage to the outside through the flange portion is suppressed, thereby improving the output torque of the rotating electric machine.

[0019] In the above aspect, it is preferable that the groove area ratio and the magnet area ratio are both 2.0.

[0020] According to this aspect, in a field element having magnets in a Halbach array, the magnetic resistance at the flange portion of the yoke is significantly increased, thereby significantly improving the output torque or power generation efficiency.

[0021] In the above aspect, the field element may form an inner rotor of an inner rotor type rotating electrical machine in which the yoke is provided along the inner peripheral surface of the magnet.

[0022] According to this aspect, since one of the circumferential groove and the plurality of radial grooves is formed in the outer flange extending radially outward of the yoke, it is easier to ensure a contact area between the flange portion and the magnet, and it is possible to suppress wobbling of the magnet during rotation, compared to when the grooves are formed in the inner flange. Also, the yoke is easy to process. [Effects of the Invention]

[0023] According to the above aspect, it is possible to provide a field element that can simultaneously prevent magnetic flux leakage and suppress a decrease in the magnet holding force. [Brief explanation of the drawings]

[0024] [Figure 1] Cross-sectional view of a motor according to an embodiment [Figure 2] A perspective view of the main part of the motor [Figure 3] A perspective view of the main parts of the motor, with the magnets visible [Figure 4] Front view of the main part of the motor with the magnets visible [Figure 5] (A) Conventional example, (B) Other embodiment, (C) Comparison of the schematic configuration of each motor according to this embodiment [Figure 6] Graph showing torque of each motor shown in Figure 5 [Figure 7] Illustrative diagram of the operation of a conventional motor DETAILED DESCRIPTION OF THE INVENTION

[0025] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments to which a field element according to the present invention is applied will be described in detail with reference to the drawings.

[0026] FIG. 1 is a cross-sectional view of a motor 1 according to an embodiment. As shown in FIG. 1, the motor 1 has a cylindrical case 3 centered on an axis 2, a rotor 4 supported by the case 3 so as to be rotatable about the axis 2, and a stator 5 disposed on the outer periphery of the rotor 4 and fixed to the case 3. In other words, the motor 1 is configured as an inner rotor type radial gap motor. While the motor 1 is used in the position shown in FIG. 1 in which the axis 2 extends horizontally, it may also be used in a position in which the axis 2 extends vertically.

[0027] The case 3 has a case body 6 and a case lid 7 that can be separated in the axial direction, and defines an internal storage space for accommodating the rotor 4 and the stator 5. The case body 6 has a cylindrical side wall 8 and a bottom wall 9 that closes the lower end of the side wall 8. A through hole 10 centered on the axis 2 is formed in the bottom wall 9 of the case body 6 and the case lid 7.

[0028] The rotor 4 includes a rotating shaft 11 that extends along the axis 2 and serves as the output shaft of the motor 1, a rotor hub 12 arranged around the rotating shaft 11, a cylindrical yoke 13 (rotor core) provided at the outer end of the rotor hub 12, and a plurality of permanent magnets (simply referred to as magnets 14). The rotor hub 12 may be provided integrally with the rotating shaft 11, or may be provided so as to be rotatable relative to the rotating shaft 11 via a planetary gear mechanism or the like. In either configuration, the rotating shaft 11 rotates as the rotor hub 12 rotates.

[0029] The rotating shaft 11 is rotatably supported by the case body 6 and the case cover 7 via bearings 15. The rotating shaft 11 passes through through holes 10 in the case body 6 and the case cover 7 and protrudes in the axial direction from both sides of the case 3. In other embodiments, the rotating shaft 11 may protrude from only one side of the case 3. The yoke 13 is a rotor core having a substantially cylindrical shape centered on the axis 2, and is formed integrally with the outer edge of the rotor hub 12, rotating integrally with the rotor hub 12. The motor 1 is a permanent magnet synchronous motor, and a plurality of magnets 14 are arranged in a predetermined circumferential arrangement on the outer periphery of the yoke 13. The rotor 4 forms a field element of the motor 1.

[0030] The stator 5 is disposed along a side wall 8 of the case body 6, with a predetermined radial gap between it and the outer surface of the rotor 4. The stator 5 includes a stator core 18 having a plurality of teeth 16 and a teeth retaining ring 17 (stator yoke) disposed outside the teeth 16 to retain the teeth 16, and a plurality of coils 19 wound around the teeth 16. The stator 5 forms the armature of the motor 1. The teeth retaining ring 17 is cylindrical and is disposed about the axis 2. The teeth 16 are aligned circumferentially along the teeth retaining ring 17 and protrude radially inward from the inner surface of the teeth retaining ring 17.

[0031] A stator cover 20 is attached to the case body 6, cooperating with the case body 6 to cover the stator 5. As shown in the enlarged view of FIG. 1 , the stator cover 20 includes a cylindrical first portion 21, a circular plate-shaped second portion 22 extending radially outward from one axial end of the first portion 21, and a circular plate-shaped third portion 23 extending radially inward from the other axial end of the first portion 21. The stator cover 20 is made of a non-magnetic material with low magnetic permeability, and may be, for example, an injection-molded synthetic resin. The first portion 21 is disposed between the stator 5 and the rotor 4 (i.e., in the gap). The second portion 22 faces the coil 19 in the axial direction of the motor 1, and its outer edge is in close contact with the side wall 8 of the case body 6 via a seal member 24. The third portion 23 is in close contact with the bottom wall 9 of the case body 6 via the seal member 24 at its inner edge.

[0032] In this way, the stator cover 20 cooperates with the case body 6 to cover the stator 5, thereby defining a cooling passage 25 for cooling the stator 5. The cooling passage 25 has a cylindrical shape, and oil supplied as a refrigerant flows through the cooling passage 25 in the axial direction.

[0033] FIG. 2 is a perspective view of essential parts of the motor 1, showing the upper part of the motor 1. The stator cover 20 is not shown. As shown in the enlarged view of FIG. 1 and FIG. 2, the yoke 13 has a cylindrical main body 26 and an annular flange 27 extending radially outward from the axial end of the main body 26. The magnet 14 has a first end face 14a and a second end face 14b located at the axial end, an inner circumferential surface 14c, and an outer circumferential surface 14d. The main body 26 of the yoke 13 is disposed along the inner circumferential surface 14c of the magnet 14 and extends in the axial direction from the first end face 14a to the second end face 14b of the magnet 14. The flange 27 of the yoke 13 extends along the first end face 14a of the magnet 14 and has an abutment surface 28 that abuts against the magnet 14.

[0034] The magnet 14 includes a first magnet 31 having a magnetic pole direction (magnetization direction) facing radially inward, a second magnet 32 ​​having a magnetic pole direction facing radially outward, and a third magnet 33 disposed between the first magnet 31 and the second magnet 32. The third magnet 33 has a magnetic pole direction that includes a circumferential component. That is, the magnets 14 are arranged in a ring shape in a Halbach array. The magnetic pole direction is indicated by arrows in the figure. The first magnet 31 and the second magnet 32 ​​are main magnets and have the same shape and dimensions. The third magnet 33 is a sub-magnet and has a smaller circumferential dimension than the main magnet. The circumferential dimension of the magnet 14 is expressed as an angle around the axis 2, and in this specification, this is referred to as the circumferential width C. The circumferential width C of the third magnet 33 is half the circumferential width C of the first magnet 31 and the second magnet 32.

[0035] Fig. 3 is a perspective view of the main parts of the motor 1, showing the magnet 14. As shown in Fig. 3, an annular circumferential groove 36 extending in the circumferential direction is formed in the abutment surface 28 of the flange portion 27 at an intermediate position spaced apart from the radial base edge 28a and the radial tip edge 28b. In addition, a plurality of radial grooves 37 extending in the radial direction from the base edge 28a to the tip edge 28b are formed in the abutment surface 28.

[0036] FIG. 4 is a front view of the main parts of the motor 1, showing the magnet 14 in a see-through manner. As shown in FIG. 4, the height (radial dimension) of the flange portion 27 is smaller than the height (radial dimension) of the magnet 14. The height of the flange portion 27 is preferably 70% or less and 30% or more of the height of the magnet 14, and more preferably 50% or less and 40% or more. In this embodiment, the height of the flange portion 27 is 45% of the height of the magnet 14.

[0037] The radial grooves 37 have a width W and are arranged at a predetermined interval P in the circumferential direction. In this specification, the circumferential interval P of the radial grooves 37 means the angular interval between the groove centers centered on the axis 2 (FIG. 1). In this embodiment, the radial grooves 37 have the same shape and dimensions as one another and are arranged at a constant interval P in the circumferential direction (at equal intervals). In other embodiments, the radial grooves 37 may be arranged at different intervals P depending on the arrangement of the magnets 14.

[0038] The circumferential spacing P of the radial grooves 37 is smaller than the circumferential width C of the third magnet 33. Therefore, at least one radial groove 37 (more specifically, one or more radial grooves 37 having a width W of at least one) is arranged in the portion of the abutment surface 28 corresponding to the third magnet 33. Furthermore, the width W of the radial groove 37 is smaller than half the circumferential spacing P of the radial grooves 37. In other words, the circumferential dimension D of the abutment portion 38 between circumferentially adjacent radial grooves 37 is larger than the width W of the radial groove 37.

[0039] The contact portions 38 located between adjacent radial grooves 37 in the circumferential direction and on both sides of the circumferential groove 36 are the portions that actually contact the magnet 14. The contact portions 38 contact the first end faces 14a (see FIG. 2) of the magnet 14, thereby positioning the magnet 14 in the axial direction. As described above, the circumferential dimension D of the contact portions 38 between the radial grooves 37 is larger than the width W of the radial grooves 37, so the contact area of ​​the flange portion 27 that actually contacts the magnet 14 is large. This ensures reliable positioning of the three types of magnets 14 that have large magnetic repulsion forces.

[0040] At this time, the tip of flange portion 27 at least partially abuts against first end face 14a (see FIG. 2) of magnet 14. This improves the holding force of magnet 14 compared to the conventional structure (Patent Document 1) in which an annular gap is provided at the tip of flange portion 27. Furthermore, by providing at least one of circumferential groove 36 and radial groove 37 on abutment surface 28, leakage of magnetic flux to the outside through flange portion 27 is suppressed. This improves the output torque of motor 1 using this field element or the power generation efficiency of the generator. The effect will be explained below with reference to FIG. 7.

[0041] 7 is an explanatory diagram of the operation of a conventional motor 101. In this motor 101, the yoke 113 of the rotor 104 has a flange portion 127, but no grooves are formed on the abutment surface 128 of the flange portion 127. Therefore, the magnetic flux that should act on the teeth 116 of the stator 105 from the outer peripheral surface 114d of the magnet 114 leaks from the first end face 114a to the flange portion 127. This causes the magnetic flux acting on the stator 105 to become sparse, reducing the output torque of the motor 101.

[0042] In contrast, in the present embodiment, as shown in FIG. 4 , the abutment surface 28 of the flange portion 27 has a circumferential groove 36 and a radial groove 37, thereby suppressing leakage of magnetic flux to the outside through the flange portion 27. Note that magnetic flux leakage includes leakage of magnetic flux passing radially through the flange portion 27 and leakage of magnetic flux passing circumferentially through the flange portion 27. Therefore, by forming at least one of the circumferential groove 36 and the radial groove 37 on the abutment surface 28, leakage of magnetic flux to the outside through the flange portion 27 is suppressed. In the present embodiment, by providing both the circumferential groove 36 and the radial groove 37 on the abutment surface 28, leakage of magnetic flux to the outside through the flange portion 27 is further suppressed. The effect of suppressing magnetic flux leakage will be described in detail later.

[0043] In this embodiment, the rotor 4 has a plurality of magnets 14 arranged in a Halbach array. Therefore, in the rotor 4 with a Halbach array, both prevention of magnetic flux leakage and suppression of a decrease in the magnet holding force are achieved.

[0044] As described above, the radial grooves 37 are arranged at regular intervals P in the circumferential direction, and this interval P is smaller than the circumferential width C of the third magnet 33, and at least one radial groove 37 is arranged in a portion of the abutment surface 28 that corresponds to the third magnet 33. Therefore, the radial groove 37 effectively prevents the circumferential magnetic flux of the third magnet 33 from leaking to the outside through the flange portion 27.

[0045] Since the first magnet 31 and the second magnet 32 ​​have the same shape and dimensions, when viewed in the axial direction as shown in FIG. 4, the area A 31 and the area A of the second magnet 32 32 Here, the area A of the radial groove 37 including the overlapping portion of the circumferential groove 36 and the radial groove 37 as viewed in the axial direction is defined as the radial groove area A 37 The area A of the circumferential groove 36 including the overlapping portion between the circumferential groove 36 and the radial groove 37 is defined as the circumferential groove area A 36 In this embodiment, the radial groove area A 37 Circumferential groove area A 36 The groove area ratio (=A 36 / A 37 ) is the area A of the third magnet 33 as viewed in the axial direction 33 The area A of the first magnet 31 31 The magnet area ratio (=A 31 / A 33 ) As a result, the magnetic resistance of the magnetic flux passing through both the circumferential groove 36 and the radial groove 37 increases, and magnetic flux leakage to the outside through the flange portion 27 is suppressed. As a result, the output torque of the motor 1 is improved.

[0046] Furthermore, in this embodiment, the circumferential width C of the third magnet 33 is half the circumferential width C of the first magnet 31 and the second magnet 32, so the groove area ratio (A 36 / A 37 ) and magnet area ratio (A 31 / A 33) are both set to 2. Therefore, in the motor 1 having the magnets 14 in the Halbach array, the magnetic resistance at the flange portion 27 is significantly increased. This significantly improves the output torque of the motor 1.

[0047] As described above, the rotor 4 forms the inner rotor of the inner rotor type motor 1 in which the yoke 13 is provided along the inner circumferential surface 14c of the magnet 14. In other words, the circumferential groove 36 and one of the plurality of radial grooves 37 are formed in the flange portion 27 (outer flange) extending radially outward from the yoke 13. Therefore, compared to when the circumferential groove 36 and one of the plurality of radial grooves 37 are formed in the inner flange, it is easier to ensure the contact area of ​​the flange portion 27 with the magnet 14, and wobbling of the magnet 14 during rotation is suppressed. In addition, the yoke 13 is easy to process.

[0048] Next, the magnetic flux leakage suppression effect of the motor 1 according to this embodiment and the motor 51 according to another embodiment of the present invention will be described with reference to FIGS. 5 and 6. FIG. 5 is a comparative diagram showing the schematic configurations of motors 101, 51, 1 according to (A) a conventional example, (B) another embodiment, and (C) this embodiment. FIG. 5(A) shows the motor 101 according to the conventional example shown in FIG. 7. FIG. 5(B) shows the motor 51 according to another embodiment of the present invention. FIG. 5(C) shows the motor 1 according to this embodiment shown in FIG. 4.

[0049] As described above, in the motor 101 according to the conventional example shown in FIG. 5(A), no grooves are formed on the contact surface 128 of the flange portion 127. In the motor 51 according to another embodiment shown in FIG. 5(B), radial grooves 37 are formed on the contact surface 28 of the flange portion 27, but circumferential grooves 36 are not formed. In the motor 1 according to this embodiment shown in FIG. 5(C), radial grooves 37 and circumferential grooves 36 are formed on the contact surface 28 of the flange portion 27. Note that in the motor 51 according to another embodiment shown in FIG. 5(B), the circumferential spacing P (see FIG. 4) of the radial grooves 37 is set so that the groove area is the same as the groove area in FIG. 5(C). The output torque of these motors 1, 51, and 101 was measured when driven under the same conditions.

[0050] FIG. 6 is a graph showing the torque of each of the motors 101, 51, and 1 shown in FIG. 5. As shown in FIG. 6, the motor 51 according to another embodiment had an output torque that was improved by 0.08% compared to the conventional motor 101. Furthermore, the motor 1 according to this embodiment had an output torque that was improved by 0.29% compared to the conventional motor 101. The only difference between these motors 1, 51, and 101 was the presence or absence of the grooves, and it was confirmed that the presence of the grooves improved the output of the motors 1 and 51 compared to the conventional motor 101.

[0051] Although the description of specific embodiments has been completed above, the present invention is not limited to the above-described embodiments and modifications, and can be widely modified and implemented. For example, in the above-described embodiments, the field element of the present invention is applied to the rotor 4 of the inner rotor motor 1, but it may also be applied to the outer rotor of an outer rotor motor. Furthermore, the field element may also be applied to the outer stator or inner stator of a rotating electric machine equipped with a rotating armature, such as a brush motor. Furthermore, the field element may also be applied to a generator rather than the motor 1. Furthermore, in this embodiment, the rotor 4 is equipped with magnets 14 in a Halbach array, but the magnet arrangement is not limited to this. In addition, the specific configuration, arrangement, quantity, and material of each member and part can be changed as appropriate without departing from the spirit of the present invention. Furthermore, not all of the components shown in the above-described embodiments are necessarily required, and can be selected as appropriate. [Explanation of symbols]

[0052] 1: Motor (an example of a rotating electrical machine) 2:Axis 4: Rotor 5: Stator 13: Yoke (rotor core) 14: Magnet 14a: First end surface 14b: Second end surface 14c: Inner peripheral surface 14d: Outer surface 26: Main body 27: Flange part 28: Contact surface 28a: proximal edge 28b: Tip edge 31: First magnet 32: Second magnet 33: Third magnet 36: Circumferential groove 37: Radial groove 38: Contact part 51: Motor (an example of a rotating electrical machine) A:Area A 31 : Area of ​​the first magnet A 32 : Area of ​​the second magnet A 33 : Area of ​​the third magnet A 31 / A 33 :Magnet area ratio A 36 :Circumferential groove area A 37 :Radial groove area A 36 / A 37 :Groove area ratio C: Circumferential width of the third magnet D: Circumferential dimension of the contact part P: Spacing W: Radial groove width

Claims

1. A field element of a rotating electric machine, a plurality of magnets arranged in a predetermined arrangement in an annular shape around the axis of the rotating electric machine; a yoke provided along one of the inner and outer peripheral surfaces of the magnet, the yoke has a cylindrical main body portion extending in the axial direction from a first end face in the axial direction of the magnet to a second end face in the axial direction, and an annular flange portion extending radially from the main body portion and having an abutment surface that abuts against the first end face of the magnet, a field element of a rotating electric machine, wherein the abutment surface has both an annular circumferential groove formed at an intermediate position spaced apart from a radial base edge and a radial tip edge of the abutment surface, and a plurality of radial grooves formed at predetermined intervals around the abutment surface and extending from the base edge to the tip edge.

2. 2. The field element of claim 1, wherein the predetermined arrangement is a Halbach array in which a third magnet having a magnetic pole direction including a circumferential component is arranged between a first magnet having a magnetic pole direction facing radially inward and a second magnet having a magnetic pole direction facing radially outward.

3. 3. The field element of a rotating electric machine according to claim 2, wherein the plurality of radial grooves are arranged at regular intervals in the circumferential direction, and the regular intervals are smaller than the circumferential width of the third magnet.

4. 4. The field element of a rotating electric machine according to claim 3, wherein a circumferential dimension of an abutting portion between a pair of said radial grooves adjacent to each other in the circumferential direction is larger than a width of said radial grooves.

5. When viewed in the axial direction, the area of ​​the first magnet and the area of ​​the second magnet are the same, 5. The field element of a rotating electric machine according to claim 4, wherein a groove area ratio, which is a ratio of an area of ​​the circumferential groove including an overlapping portion between the circumferential groove and the radial groove to an area of ​​the radial groove including the overlapping portion when viewed in the axial direction, is the same as a magnet area ratio, which is a ratio of an area of ​​the first magnet or the second magnet to an area of ​​the third magnet when viewed in the axial direction.

6. 6. The field element of claim 5, wherein the groove area ratio and the magnet area ratio are both 2.

7. 7. The field element for a rotating electric machine according to claim 1, wherein the field element forms an inner rotor of an inner rotor type rotating electric machine in which the yoke is provided along the inner peripheral surface of the magnet.

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