Core, stator, and rotating electrical machine

Abstract

Provided is a core used in a rotating electrical machine of an axial gap type, the core comprising a first member and a second member combined with the first member. The first member is formed of at least one powder compact. The powder compact comprises a plurality of teeth having columnar shapes and a flange part that integrally couples first end portions of the plurality of teeth. The outer form of the flange part in a plan view has an arc shape or an annular shape. The plurality of teeth are disposed at equal intervals in the direction along the arc shape or the annular shape. The outer form of the second member in a plan view has an annular shape. Second end portions of each of the plurality of teeth and the second member are coupled.

Description

Cores, stators, and rotating electric machines

[0001] This disclosure relates to cores, stators, and rotating electric machines. This application claims priority under Japanese Patent Application No. 2024-209525 dated 2 December 2024, incorporating all the provisions contained herein.

[0002] A rotating electric machine, such as a motor or generator, comprises a rotating shaft, a rotor, and a stator. Patent documents 1 to 3 disclose axial gap type rotating electric machines. In an axial gap type rotating electric machine, the rotor and stator are arranged in a direction along the length of the rotating shaft. A rotating electric machine with one rotor and one stator is called a single-rotor, single-stator type rotating electric machine. A rotating electric machine with one rotor and two stators is called a single-rotor, double-stator type rotating electric machine. A rotating electric machine with two rotors and one stator is called a double-rotor, single-stator type rotating electric machine.

[0003] The rotor is fixed to the rotation axis and rotates together with the rotation axis. The stator includes a core and a plurality of coils. The core constituting the stator of a single-rotor single-stator type or double-rotor single-stator type rotating electrical machine includes an annular plate yoke and a plurality of columnar teeth protruding from one surface of the yoke. Among the teeth, a flange-like collar portion extending from the circumferential surface of the teeth may be formed at the end portion facing the rotor. The collar portion faces the rotor in the rotating electrical machine. The shape of the core having collar portions on each of the plurality of teeth is complex. Therefore, the core having collar portions is constituted by combining a plurality of members. The core described in Patent Document 1 is constituted by preparing a plurality of tooth members in which one tooth and one collar portion are integrated, and combining the plurality of tooth members and an annular yoke. The core described in Patent Document 2 is constituted by combining a yoke member in which a plurality of teeth and the yoke are integrated, and a collar portion attached to each tooth. The core described in Patent Document 3 is constituted by preparing a plurality of tooth members in which one tooth, one collar portion, and a part of the yoke are integrally formed, and arranging the plurality of tooth members in an annular shape.

[0004] International Publication No. 2020 / 022094, International Publication No. 2020 / 100385, International Publication No. 2021 / 225049

[0005] The core of this disclosure is used in an axial gap type rotating electric machine and comprises a first member and a second member combined with the first member. The first member is formed from at least one compacted body, the compacted body comprising a plurality of columnar teeth and a flange that integrally connects the first ends of the plurality of teeth. The flange has a first surface on which the plurality of teeth are arranged to protrude, and a second surface opposite to the first surface and facing the rotor used in the rotating electric machine. The outer shape of the flange when viewed from above the first surface is arc-shaped or annular-shaped. The plurality of teeth are arranged at equal intervals in a direction along the arc-shaped or annular-shaped surface. The second member has a third surface facing the first surface and a fourth surface opposite to the third surface. The outer shape of the second member when viewed from above the third surface is annular-shaped. The second end of each of the plurality of teeth is connected to the second member.

[0006] Figure 1 is a schematic longitudinal cross-sectional view of a single-rotor, single-stator type rotating electric machine according to Embodiment 1. Figure 2 is a schematic exploded view of the core provided in the rotating electric machine of Figure 1. Figure 3 is a schematic partial plan view of the first member, viewed from the first surface. Figure 4 is a schematic partial plan view illustrating a different small cross-sectional area from Figure 3. Figure 5 is a schematic partial cross-sectional view illustrating a different small cross-sectional area from Figures 3 and 4. Figure 6 is a schematic partial cross-sectional view showing the connection state between the first member and the second member. Figure 7 is a schematic partial cross-sectional view illustrating a different connection state between the first member and the second member from Figure 6. Figure 8 is a schematic perspective view of the first member according to Embodiment 2. Figure 9 is a schematic plan view of the first member and the second member according to Embodiment 3. Figure 10 is a schematic configuration diagram of a mold for compacting the second member of Figure 9. Figure 11 is a schematic configuration diagram of the first member and the second member according to Embodiment 4.

[0007] In axial gap type rotating electric machines, a thrust force acts on the flange of the core during operation. This thrust force is the force with which the rotor pulls the flange during operation. When a thrust force acts on the flange of the core, the relative positions of the multiple components that make up the core may change. For example, in the configuration of Patent Document 1, the teeth member may be displaced relative to the yoke. In the configuration of Patent Document 2, the flange may be displaced relative to the teeth. In the configuration of Patent Document 3, the relative positions of the multiple teeth members may change. As described above, when the relative positions of multiple components change, the characteristics of the motor may change.

[0008] One of the purposes of this disclosure is to provide a core for use in an axial gap type rotating electric machine composed of multiple members, in which the relative positions of the multiple members do not change easily even when a thrust force is applied. Another purpose of this disclosure is to provide a stator equipped with the core of this disclosure, and a rotating electric machine equipped with the stator of this disclosure.

[0009] The core of this disclosure is used in an axial gap type rotating electric machine composed of multiple members, and the relative positions of the multiple members do not change easily even when a thrust force is applied.

[0010] First, the embodiments of this disclosure will be listed and described.

[0011] <1> The core according to the embodiment is a core used in an axial gap type rotating electric machine and comprises a first member and a second member combined with the first member. The first member is formed from at least one compacted body, the compacted body comprises a plurality of columnar teeth and a flange that integrally connects the first ends of the plurality of teeth. The flange has a first surface on which the plurality of teeth are arranged to protrude, and a second surface on the opposite side of the first surface, facing the rotor used in the rotating electric machine. The outer shape of the flange when viewed from above the first surface is an arc shape or an annular shape. The plurality of teeth are arranged at equal intervals in the direction along the arc shape or annular shape. The second member has a third surface facing the first surface and a fourth surface opposite to the third surface. The outer shape of the second member when viewed from above the third surface is an annular shape. The second end of each of the plurality of teeth is connected to the second member.

[0012] The flange formed at the first end of the teeth constituting the first component is the component that faces the rotor in a rotating electric machine such as a motor. Considering its function in a rotating electric machine, the flange is sometimes called a pole shoe. On the other hand, the plate-shaped second component located at the second end of the teeth, opposite to the first end, functions as a yoke in a single-rotor type rotating electric machine. The yoke is a component that does not face the rotor in a rotating electric machine. The second component can function as a flange in a double-rotor type rotating electric machine.

[0013] As already mentioned, during the operation of an axial gap type rotating electric machine, a thrust force acts on the flange of the core in the direction toward the rotor along the axis of rotation. If the teeth and the flange were independent members, there would be a risk of the flange being displaced or detached from the teeth. In this example, the flange constitutes a first member integrated with multiple teeth, so even if a thrust force acts on the flange, the flange will not be displaced or detached from the teeth. Furthermore, although the first member and the second member are connected at the position of the second end of the teeth on the first member, the possibility of the first member being displaced or detached from the second member due to thrust force is low. This is because, in the first member, which has a large mass due to the presence of multiple teeth, the thrust force per unit mass is small, making it difficult for the first member to move due to thrust force. Here, in this specification, "the first member and the second member are connected" means "the positional relationship between the first member and the second member is determined so that magnetic flux flows through the part where the first member and the second member are in contact."

[0014] Conventional cores have the problem of requiring a large number of constituent members, making core manufacturing complicated. The cores described in Patent Documents 1 to 3 all require at least the same number of members as the number of teeth. On the other hand, in the core described in <1> above, since multiple teeth are connected by a flange, the number of constituent members of the core is less than the number of teeth. The minimum number of members is two, consisting of one first member and one second member.

[0015] <2> In the core described in <1> above, the first member is formed from a single compacted body, and the flange portion may have the annular shape.

[0016] According to the configuration described in <2> above, the core is completed simply by combining the first and second members, resulting in excellent core productivity. Furthermore, in the configuration described in <2> above, the total mass of the first member is large, so even when thrust force acts on the first member during the operation of the rotating electric machine, the first member is less likely to be displaced relative to the second member.

[0017] <3> In the core described in <1> or <2> above, the plurality of teeth include adjacent first teeth and second teeth, and the flange portion may have a small cross-sectional area in the region between the first teeth and the second teeth where the magnetic path cross-sectional area is locally small.

[0018] By having a small cross-sectional area in the region between the first and second teeth of the flange, the characteristics of the rotating electric machine are more easily improved than if the flange had a uniform cross-sectional area.

[0019] <4> In the core described in <3> above, the small cross-sectional portion may include a line bisector that divides the distance between the first tooth and the second tooth in half.

[0020] The characteristics of a rotating electric machine are more easily improved when the small cross-section is positioned away from the teeth rather than in contact with them. If the small cross-section is positioned on the line bisector that divides the distance between the first and second teeth, the small cross-section is sufficiently far from the first and second teeth, and the difference between the distance from the first tooth to the small cross-section and the distance from the second tooth to the small cross-section becomes small. As a result, the characteristics of the rotating electric machine are more easily improved, such as increased torque.

[0021] <5> In the core described in <3> or <4> above, the small cross-sectional portion may include an outer peripheral notch extending from the outer peripheral edge to the inner peripheral edge of the flange portion.

[0022] The flange portion has an outer notch, which creates a small cross-section on the flange portion. The outer notch can be easily formed by a mold used to form the compacted body.

[0023] <6> In the core described in any of <3> to <5> above, the small cross-sectional portion may include an inner circumferential notch extending from the inner circumferential edge toward the outer circumferential edge of the flange portion.

[0024] The flange portion has an inner circumference notch, which creates a small cross-section in the flange portion. The inner circumference notch can be easily formed by a mold used to form the compacted powder body.

[0025] <7> In the core described in any of <3> to <6> above, the small cross-sectional portion may include a recess formed on at least one of the first surface and the second surface.

[0026] The flange portion has a recess, which creates a small cross-section in the flange portion. The recess can be easily formed by a mold used to form the compacted powder body.

[0027] <8> In the core described in any of <1> to <7> above, the second member may be a flange portion separate from the flange portion.

[0028] The core, which forms the flange portion of the second component, can be used as the core of a double-rotor type rotating electric machine.

[0029] <9> In the core described in any of <1> to <7> above, the second member may be a yoke.

[0030] The core, which forms the yoke of the second component, can be used as the core of a single-rotor type rotating electric machine.

[0031] <10> In the core described in any of <1> to <9> above, the second member may have a recess or through hole into which the second end is fitted.

[0032] The first member is connected to the second member by fitting the second end of the teeth into a recess or through hole. In this configuration, even if there is variation in the height of the multiple teeth of the first member, the flange and the second member can be made nearly parallel. As a result, torque pulsation in rotating electric machines is easily reduced.

[0033] <11> In the core described in <10> above, the second end does not have to protrude from the through hole to the fourth surface.

[0034] In rotating electric machines, the second component of the core may be fixed to a mounting object such as a case. For this fixing, the fourth surface of the second component may be positioned to face the inner surface of the case. In this case, if the second end of the teeth does not protrude from the fourth surface of the second component, the second component can be made to make surface contact with the mounting object. As a result, the core's fixing to the mounting object becomes more stable, and the heat dissipation of the core is improved.

[0035] <12> In the core described in <11> above, the length over which the through hole and the second end overlap in the thickness direction of the second member from the third surface toward the fourth surface may be 90% or more of the length of the through hole.

[0036] According to the configuration described in <12> above, the contact area between the teeth and the second member becomes sufficiently large, allowing magnetic flux to flow easily between the teeth and the second member. As a result, the torque of the rotating electric machine is less likely to decrease.

[0037] <13> In the core described in any of <10> to <12> above, the variation in length from the fourth surface of the second member to the second surface of the flange portion may be 0.05 mm or less.

[0038] The variation in length can be determined, for example, by measuring the length from the fourth face to the second face at the position of each tooth. The variation in length is the value obtained by subtracting the minimum length from the maximum length. If the variation in length is 0.05 mm or less, the distance between the core and rotor in the rotating electric machine tends to be uniform, thus reducing the cogging torque in the rotating electric machine.

[0039] <14> In the core described in any of <1> to <13> above, at least some of the teeth of the plurality of teeth may have screw holes on the end faces of the second end.

[0040] For example, a screw is placed in the screw hole to connect the teeth to the second member. In this case, the first member and the second member are firmly connected, preventing them from coming apart.

[0041] When a through-hole is formed in the second member and the second end portion of the teeth is fitted into the through-hole, a screw for fixing the core to the mounting target may be disposed in the screw hole. In this case, the core can be firmly fixed to the mounting target, and the core can be prevented from coming off from the mounting target.

[0042] Here, the screw hole means a hole in which a screw is disposed. It does not matter whether a screw groove is formed on the inner peripheral surface of the screw hole before the screw is disposed. For example, when a tapping screw is disposed in the screw hole, a screw groove is not formed on the inner peripheral surface of the screw hole before the tapping screw is disposed.

[0043] <15> In the core according to <14> above, the number of the screw holes may be less than the number of the plurality of teeth.

[0044] If the number of screw holes is less than the number of teeth, the number of times of screwing can be reduced when screwing the first member and the second member or screwing the core to the mounting target.

[0045] <16> In the core according to <2> above, or any one of <3> to <15> citing <2>, the second member is formed of a powder compact different from the first member, and the outer peripheral shape of the flange portion and the outer peripheral shape of the second member may be the same shape.

[0046] As described in Embodiment 3 to be described later, if the outer peripheral shape of the flange portion and the outer peripheral shape of the second member are the same shape, the die of the mold for powder compacting the first member and the second member can be shared.

[0047] <17> In the core according to <2> above, or any one of <3> to <16> citing <2>, the second member is formed of a powder compact different from the first member, and the inner peripheral shape of the flange portion and the inner peripheral shape of the second member may be the same shape.

[0048] As described in Embodiment 3 to be described later, if the inner peripheral shape of the flange portion and the inner peripheral shape of the second member are the same shape, the core of the mold for powder compacting the first member and the second member can be shared.

[0049] <18> The stator according to the embodiment is a stator used in an axial gap type rotating electric machine, and comprises a core as described in any of <1> to <17> above, and coils arranged on each of the plurality of teeth.

[0050] The stator described in <18> above maintains stable motor performance in a rotating electric machine. This is because, even when a thrust force is generated in the stator core during the operation of the rotating electric machine, the flange portion does not displace relative to the teeth, and the first member, including the flange portion and the teeth, is less likely to displace relative to the second member.

[0051] <19> The rotating electric machine according to the embodiment includes the stator described in <18> above.

[0052] The rotating electric machine described in <19> above is equipped with a stator that maintains stable magnetic properties, and therefore exhibits stable performance.

[0053] Specific examples of the core, stator, and rotating electric machine of this disclosure will be described below with reference to the drawings. Identical reference numerals in the drawings indicate the same or corresponding parts. The dimensions of the components shown in each drawing are for illustrative purposes only and do not necessarily represent actual dimensions. The present invention is not limited to these examples, but is indicated by the claims, and all modifications within the meaning and scope of the claims are intended to be included. It should be understood that at least one configuration or feature described in each embodiment and example can be combined with other embodiments and examples, or modified in various ways.

[0054] <Embodiment 1> The rotating electric machine 1 of this example shown in Figure 1 comprises a rotating shaft 10, a stator 2, a rotor 3, and a case 4. The stator 2 comprises a core 20 and a coil 25 and is fixed inside the case 4. The rotor 3 is fixed to the rotating shaft 10 and rotates together with the rotating shaft 10. The case 4 houses the stator 2, the rotor 3, and a part of the rotating shaft 10. The stator 2 and the rotor 3 are arranged in series in a direction along the length of the rotating shaft 10. In other words, the rotating electric machine 1 of this example is a single-rotor, single-stator type and an axial-gap type rotating electric machine 1.

[0055] One of the features of the rotating electric machine 1 in this example is the segmented structure of the core 20. First, the main components of the rotating electric machine 1 will be explained, and then the segmented structure of the core 20 will be explained. In this explanation, the direction from the stator 2 toward the rotor 3 along the rotation axis 10 will be defined as the first direction D1, and the direction opposite to the first direction D1 will be defined as the second direction D2.

[0056] ≪Rotational Shaft≫ The rotational shaft 10 has a first end 10A positioned in the first direction D1 and a second end 10B positioned in the second direction D2. The first end 10A protrudes to the outside of the case 4, which will be described later. When the rotating electric machine 1 is a motor, the first end 10A functions as an output end attached to the drive object. When the rotating electric machine 1 is a generator, the first end 10A functions as an input end attached to the rotational power.

[0057] Unlike this example, the rotating shaft 10 may penetrate the case 4. That is, both the first end 10A and the second end 10B of the rotating shaft 10 may protrude to the outside of the case 4. In that case, both the first end 10A and the second end 10B may be used as either an output terminal or an input terminal.

[0058] ≪Stator≫ The core 20 of the stator 2 comprises a plurality of teeth 6, a flange portion 7, and a yoke 8. As shown in Figure 6, the teeth 6 are columnar members having a length along the first direction D1. The teeth 6 have a first end portion 6A including a first end face 6a facing the first direction D1, and a second end portion 6B opposite to the first end portion 6A. The first end portion 6A is a portion having a predetermined length from the first end face 6a closest to the rotor 3 (see Figure 1) toward the second direction D2. The second end portion 6B is a portion having a predetermined length from the second end face 6b facing the second direction D2 toward the first direction D1.

[0059] In this example, the stator 2 is fixed to the inner surface 4S of the case 4 by a screw 45. This screw 45 also plays a role in strengthening the connection between the teeth 6 and the yoke 8. Its role will be described later.

[0060] The flange portion 7 is a ring-shaped plate material, as shown in Figure 2. The flange portion 7 integrally connects the first ends 6A (see Figure 6) of multiple teeth 6. In Figure 6, the conceptual boundary between the teeth 6 and the flange portion 7 is shown by a dashed line. More specifically, the flange portion 7 extends from the side of the tooth 6 toward the side of the tooth 6, from the first end 6A of the tooth 6. Lateral refers to the direction perpendicular to the central axis of the tooth 6 along the first direction D1, and away from the central axis, i.e., the radial direction. The surface of the flange portion 7 facing the first direction D1 is flush with the first end face 6a of the tooth 6. The flange portion 7 is positioned close to the rotor 3 and is a component facing the rotor 3. The shape of the flange portion 7 in this example will be described later.

[0061] As shown in Figure 2, the yoke 8 is an annular-shaped member. The yoke 8 is positioned away from the rotor 3. In other words, unlike the flange 7, the yoke 8 is a member that does not face the rotor 3. As shown in Figure 6, the yoke 8 is positioned at the second end 6B of the teeth 6. In this example, the second end 6B is fitted into a through hole 90 formed in the yoke 8.

[0062] ≪Rotor≫ As shown in Figure 1, the rotor 3 comprises a rotor back yoke 30 and a plurality of magnets 32. The rotor back yoke 30 is an annular plate through which the rotating shaft 10 passes. The rotor back yoke 30 is fixed to the rotating shaft 10, and the rotor back yoke 30 and the rotating shaft 10 rotate coaxially. The rotor back yoke 30 has a base surface facing the stator 2.

[0063] Multiple magnets 32 are fixed to the base surface, for example, by adhesive. The magnets 32 are permanent magnets. The multiple magnets 32 are arranged at approximately equal intervals around the axis of the rotation shaft 10. The shape of the magnets 32 is, for example, a flat plate corresponding to the shape of the first end face 6a of the teeth 6. The magnets 32 are magnetized in a direction along the axis of the rotation shaft 10. The magnetization directions of two adjacent magnets 32 around the axis of the rotation shaft 10 are opposite to each other. The rotor 3 rotates relative to the stator 2 as the magnets 32 are attracted to or repelled by the teeth 6 by the rotating magnetic field generated by the stator 2.

[0064] ≪Case≫ Case 4 comprises a box-shaped case body 40 having an opening, and a cover 41 that closes the opening. The cover 41 is screwed to the case body 40 by screws 49. The stator 2 and rotor 3 are housed in the internal space enclosed by the case body 40 and the cover 41.

[0065] Inside the case 4 are a first bearing 11 and a second bearing 12, which rotatably support the rotating shaft 10 in the case 4. The first bearing 11 supports the portion of the rotating shaft 10 between the first end 10A and the second end 10B at the bottom of the case body 40. The second bearing 12 supports the second end 10B at the cover 41.

[0066] ≪Core Divided Structure≫ As shown in Figure 2, the core 20 in this example is composed of a combination of a first member 5 and a second member 9. The first member 5 in this example is a member in which multiple teeth 6 and a flange portion 7 are integrated. The second member 9 is a yoke 8. In the following description, the surface of the flange portion 7 facing the second member 9 will be referred to as the first surface S1, and the surface opposite to the first surface S1 will be referred to as the second surface S2. The second surface S2 is the surface facing the rotor 3 (see Figure 1). Furthermore, of the second member 9, the surface of the flange portion 7 facing the first surface S1 will be referred to as the third surface S3, and the surface opposite to the third surface S3 will be referred to as the fourth surface S4. The fourth surface S4 is the surface facing the inner surface 4S of the case 4 (see Figure 1).

[0067] [First Member] The first member 5 is formed by a compacted molded body 50. The compacted molded body 50 is formed by pressurizing a raw material powder containing magnetic powder. The magnetic powder is, for example, an aggregate of at least one type of magnetic particle selected from pure iron with a Fe (iron) purity of 99% by mass or higher, and iron alloys. Examples of iron alloys are Fe-Si (silicon)-Al (aluminum) alloys, F-Si alloys, Fe-Al alloys, and Fe-Ni (nickel) alloys. The magnetic particles constituting the magnetic powder may have an insulating coating on their surface. The insulating coating is, for example, a phosphate coating or a silica coating. The raw material powder may contain a binder. The binder may be a powder or a liquid.

[0068] The compacted molded body 50 in this example, i.e., the first member 5, comprises twelve teeth 6 and one flange portion 7. All teeth 6 protrude from the first surface S1 of the flange portion 7. The direction of protrusion of the teeth 6 is perpendicular to the first surface S1 and is a second direction D2 toward the third surface S3 of the second member 9 from the first surface S1. The teeth 6 in this example have a roughly triangular prism shape. The number of teeth 6 can be multiple and is not particularly limited. The shape of the teeth 6 can also be columnar and is not particularly limited. Unlike this example, the teeth 6 may be, for example, roughly trapezoidal prism-shaped.

[0069] The flange portion 7 that connects multiple teeth 6 is an annular plate material. In contrast, the conventional flange portions described in Patent Documents 1 to 3 are formed one on each of the multiple teeth 6, and these flange portions are not connected. In the conventional structure, the flange portions of two adjacent teeth 6 are not connected in order to reduce magnetic flux leakage between two adjacent teeth 6, 6 and reduce the decrease in torque of the rotating electric machine 1.

[0070] Multiple teeth 6 are arranged at equal intervals in a direction along the arc shape of the flange 7. The direction along the arc shape is either clockwise or counterclockwise around the central axis 7c of the flange 7.

[0071] As shown in Figure 3, in the radial directions 7r, 7r1, and 7r2 of the annular flange 7, the width of the flange 7 is, for example, greater than that of the teeth 6. The radial directions 7r, 7r1, and 7r2 are radial directions perpendicular to the central axis 7c of the annular shape and moving away from the central axis 7c. In other words, there are infinitely many radial directions 7r, 7r1, and 7r2. In the following explanation, the directions along the radial directions 7r, 7r1, and 7r2 may be referred to as outward, and the directions opposite to the radial directions 7r, 7r1, and 7r2 may be referred to as inward. In this example, when viewed from the direction along the central axis 7c, the inner peripheral edge 7Y of the flange 7 is positioned inward from the inner edge of the teeth 6. Also, when viewed from the direction along the central axis 7c, the outer peripheral edge 7X of the flange 7 is positioned outward from the outer edge of the teeth 6. The inner peripheral edge 7Y of the flange portion 7 is the edge that constitutes the smallest virtual circle inscribed within the flange portion 7 when the annular-shaped flange portion 7 is viewed from a direction along the central axis 7c. The outer peripheral edge 7X of the flange portion 7 is the edge that constitutes the smallest virtual circle circumscribed outside the flange portion 7 when the annular-shaped flange portion 7 is viewed from a direction along the central axis 7c. Unlike this example, the inner peripheral edge 7Y of the flange portion 7 may coincide with the inner edge of the teeth 6, and the outer peripheral edge 7X of the flange portion 7 may coincide with the outer edge of the teeth 6.

[0072] In this example, the flange portion 7 is provided with a small cross-sectional area 70 in the region 7R between the adjacent first teeth 61 and second teeth 62, where the magnetic path cross-sectional area is locally small. Here, the names first teeth 61 and second teeth 62 are merely names used to distinguish teeth 6 that are adjacent to each other in the direction along the annular shape of the flange portion 7. For example, when looking at the two teeth 6 in Figure 2, the second tooth 62 and the tooth 6 to its right, one tooth 6 is the first tooth 61 and the other tooth 6 is the second tooth 62.

[0073] Region 7R is the region sandwiched between the first tooth 61 and the second tooth 62 in the direction along the annular shape of the flange 7 when the first surface S1 of the flange 7 is viewed from above. More specifically, region 7R is the region enclosed by the first tooth 61, the second tooth 62, an inner arc R1, and an outer arc R2. The inner arc R1 is an arc that connects the inner end of the first tooth 61 and the inner end of the second tooth 62 along the circumferential direction of the flange 7. The outer arc R2 is an arc that connects the outer end of the first tooth 61 and the outer end of the second tooth 62 along the circumferential direction of the flange 7. A magnetic path is formed in this region 7R along the circumferential direction of the flange 7. If a small cross-sectional area 70 with a locally small magnetic path cross-sectional area is formed in this region 7R, magnetic flux will not flow easily between the first tooth 61 and the second tooth 62 at the location of the flange 7. As a result, in the rotating electric machine 1 (Figure 1), the magnetic flux passing between the core 20 and the rotor 3 increases, making it easier to improve the magnetic properties of the core 20.

[0074] The small cross-section portion 70 is the portion having a smaller area when multiple cross-sections are taken by cutting region 7R with planes along each of the following different radial directions 7r, 7r1, and 7r2. More specifically, the small cross-section portion 70 is the portion sandwiched between the first cross-section and the second cross-section below, with a smaller cross-sectional area than the first and second cross-sections. The first cross-section is the cross-section obtained by cutting region 7R with a plane along radial direction 7r1 that is in contact with the part of the first tooth 61 closest to the second tooth 62. The second cross-section is the cross-section obtained by cutting region 7R with a plane along radial direction 7r2 that is in contact with the part of the second tooth 62 closest to the first tooth 61. The radial direction 7r is the direction along the line bisector that divides the distance between adjacent first teeth 61 and second teeth 62 in half.

[0075] The small cross-section portion 70 in this example includes an outer peripheral notch 71. The outer peripheral notch 71 extends from the outer peripheral edge 7X of the flange portion 7 toward the inner peripheral edge 7Y. The outer peripheral notch 71 includes a bisector along the radial direction 7r and has a length along the radial direction 7r. The inner edge of the outer peripheral notch 71 is located inward of the outer circular arc R2. The outer peripheral notch 71 can be easily formed by a mold for molding the compacted body 50. The small cross-section portion 70 in this example, including the outer peripheral notch 71, is the portion enclosed by the inner circular arc R1, the outer circular arc R2, the first straight line R3, and the second straight line R4. The first straight line R3 is a radial tangent to the portion of the outer peripheral notch 71 closest to the first tooth 61. The second straight line R4 is a radial tangent to the portion of the outer peripheral notch 71 closest to the second tooth 62.

[0076] In this example, the outer notches 71 are formed in each of several distinct regions 7R. Since each region 7R is formed between adjacent first teeth 61 and second teeth 62, there are 12 regions 7R in this example. In other words, there are 12 outer notches 71 in this example.

[0077] The outer edge of the outer notch 71 is located outward from region 7R. The inner edge of the outer notch 71 is located inward from region 7R. Unlike this example, the outer edge of the outer notch 71 may overlap with the outer arc R2, which is the outer edge of region 7R, or it may be located inward from the outer arc R2. Similarly, the inner edge of the outer notch 71 may overlap with the inner arc R1, which is the inner edge of region 7R, or it may be located inward from the inner arc R1.

[0078] The small cross-section portion 70 may be in the form shown in Figure 4 or Figure 5. The small cross-section portion 70 shown in Figure 4 includes an inner circumferential notch 72 extending from the inner circumferential edge 7Y toward the outer circumferential edge 7X of the flange portion 7. The inner circumferential notch 72 includes a radial bisector and has a length along the radial direction 7r. The outer edge of the inner circumferential notch 72 is positioned outward from the inner circular arc R1. The inner circumferential notch 72 can be easily formed by a mold for molding the compacted body 50.

[0079] The small cross-sectional portion 70 shown in Figure 5 includes a recess 73 formed on the first surface S1. Figure 5 is a cross-sectional view obtained by cutting the first member 5 with an arc cross section perpendicular to the bisector that divides the width of the first teeth 61 and the second teeth 62. The recess 73 may be formed on the second surface S2, or on both the first surface S1 and the second surface S2. The recess 73 can be easily formed by a mold for molding the compacted body 50.

[0080] The shape of the recess 73 when the first surface S1 is viewed from above may be, for example, an elongated shape along the radial direction 7r, or it may be circular. There may be multiple recesses 73 formed in a single region 7R. For example, multiple circular recesses 73 may be arranged radially in a single region 7R. Unlike this example, the recess 73 may also be a through hole opening into the first surface S1 and the second surface S2.

[0081] In addition, the flange portion 7 may include at least two of the outer circumference notches 71, inner circumference notches 72, or recesses 73 shown in Figures 3 to 5, respectively. For example, the flange portion 7 may include both the outer circumference notches 71 and the inner circumference notches 72.

[0082] [Second Member] As shown in Figures 1 and 2, the second member 9 in this example functions as a yoke 8 in the rotating electric machine 1. As shown in Figure 2, the second member 9 is an annular plate material having a third surface S3 and a fourth surface S4. The second member 9 may be formed from a powder compacted body separate from the first member 5, or it may be formed from an SS400 plate, a SUS plate, or a laminated steel plate.

[0083] When both the first member 5 and the second member 9 are formed by compacted powder molding, the magnetic powder constituting the first member 5 and the magnetic powder constituting the second member 9 may be the same or different. "The magnetic powder constituting the first member 5 and the magnetic powder constituting the second member 9 are different" means that at least one of the following is different: for example, the average particle size of the magnetic powder, the material of the magnetic particles constituting the magnetic powder, and the material of the insulating coating formed on the magnetic particles. Of the first member 5 and the second member 9, the member that is less likely to affect the motor performance of the rotating electric machine 1 may be formed from an inexpensive magnetic powder.

[0084] In this example, the second member 9 is a single member. Unlike this example, the second member 9 may be composed of multiple segmented pieces. In that case, the segmented pieces may be, for example, arc-shaped plates. If the shape of the multiple segmented pieces is the same, only one mold is needed to manufacture the segmented pieces.

[0085] [Connection between the first and second members] As shown in Figure 6, the second end 6B of the teeth 6 of the first member 5 is connected to the second member 9. In other words, the first member 5 and the second member 9 are connected. In this example, the second member 9 has a through hole 90, and the second end 6B is fitted into the through hole 90, thereby connecting the first member 5 and the second member 9.

[0086] In this example, the first member 5 and the second member 9 are firmly connected by a screw 45. Specifically, the screw 45 penetrates from the outside of the case 4 towards the through hole 90 of the second member 9 and is screw-connected to the screw hole 60 of the teeth 6. The case 4 has a through hole 4h through which the screw 45 is inserted and a counterbore 4c connected to the through hole 4h. The head of the screw 45 is housed in the counterbore 4c and does not protrude from the outer surface of the case 4. One screw hole 60 is formed on the second end face 6b of the teeth 6. The screw 45 that is screw-connected to the screw hole 60 may be a tapping screw or a regular screw other than a tapping screw. In the case of a tapping screw, no screw groove is formed in the screw hole 60 before it connects the first member 5 and the second member 9. When the tapping screw is placed in the screw hole 60, the tapping screw forms a screw groove on the inner surface of the screw hole 60. The screw connection by the screw 45 determines the position of the teeth 6 within the case 4, and firmly connects the second end 6B of the teeth 6 to the second member 9. Unlike this example, the second end 6B of the teeth 6 may also be connected to the second member 9 simply by fitting it into the through hole 90.

[0087] As shown in Figure 2, the screw holes 60 are formed on every other tooth 6. In other words, the number of screw holes 60 is less than the number of teeth 6. The fewer the number of screw holes 60, the less effort is required to install the screws 45. On the other hand, the more screw holes 60 there are, the stronger the connection between the first member 5 and the second member 9 becomes. When forming screw holes 60 on some of the teeth 6 among the multiple teeth 6, it is preferable to arrange the screw holes 60 at equal intervals in the direction along the annular shape of the flange portion 7. For example, as in this example, if screw holes 60 are formed on every other tooth 6, the mounting strength between the first member 5 and the second member 9 is less likely to vary in the direction along the annular shape of the second member 9. Also, the work of installing the screws 45 is less burdensome. Unlike this example, the number of screw holes 60 may be the same as the number of teeth 6.

[0088] The second end face 6b of the teeth 6 fitted into the through hole 90 may be flush with the fourth face S4 of the second member 9, or it may be located in a first direction D1 relative to the fourth face S4, or it may be located in a second direction D2 relative to the fourth face S4. In this example, the second end face 6b is located in a first direction D1 relative to the fourth face S4. That is, the second end 6B fitted into the through hole 90 does not protrude from the fourth face S4 of the second member 9. Therefore, the fourth face S4 of the second member 9 can be in surface contact with the inner surface 4S of the case 4. As a result, the fixing of the core 20 inside the case 4 is stabilized. In addition, the heat from the core 20 can easily escape into the case 4, so the output of the rotating electric machine 1 is more likely to improve.

[0089] In the thickness direction of the second member 9 from the third surface S3 to the fourth surface S4, the length Lt over which the through hole 90 and the second end 6B overlap is, for example, 90% or more of the length Ly of the through hole 90. In other words, the lengths Lt and Ly satisfy the inequality (Lt / Ly) × 100 > 90. In this case, the contact area between the second end 6B of the teeth 6 in the through hole 90 and the second member 9 becomes sufficiently large, making it easier for magnetic flux to flow between the teeth 6 and the second member 9, which is the yoke 8. Therefore, the torque of the rotating electric machine 1 is less likely to decrease. In addition, the connection of the teeth 6 to the second member 9 becomes stronger, and heat from the first member 5 can easily escape to the case 4 through the second member 9. When (Lt / Ly) × 100 is 100, the second end surface 6b is flush with the fourth surface S4.

[0090] In a configuration in which the second end 6B of the teeth 6 is fitted into the through hole 90, even if there is variation in the lengths of the multiple teeth 6 provided on the first member 5, the variation in the length from the fourth surface S4 of the second member 9 to the second surface S2 of the flange portion 7 of the first member 5 can be reduced. The variation in length can be determined, for example, by measuring the length from the fourth surface S4 to the second surface S2 at the position of each tooth 6. The value obtained by subtracting the minimum length from the maximum length is the variation in length. The variation is, for example, 0.05 mm or less. If the variation in length is 0.05 mm or less, the distance between the core 20 and the rotor 3 in the rotating electric machine 1 shown in Figure 1 is more likely to be uniform, and thus the torque pulsation in the rotating electric machine 1 can be reduced.

[0091] The connection between the first member 5 and the second member 9 may be the connection configuration shown in Figure 7. In the example in Figure 7, the first member 5 and the second member 9 are directly connected by a screw 45. In this case, the second member 9 has a through hole 95 through which the screw 45 is inserted. The inner diameter of the through hole 95 is slightly larger than the outer diameter of the screw 45, so the second end portion 6B cannot be fitted into the through hole 95. When fixing the core 20 having this connection configuration to the case 4 in Figure 1, it is preferable to form a counterbore on the inner surface 4s of the cover 41 to accommodate the head of the screw 45.

[0092] The connection state of the first member 5 and the second member 9 is not limited to the connection state illustrated in Figures 6 and 7. For example, the second end face 6b of the teeth 6 may be bonded to the third surface S3 of the second member 9. Alternatively, a projection may be formed on the second end face 6b, and a recess may be formed on the third surface S3 of the second member 9 into which the projection is fitted.

[0093] When the connected core 20 described above is applied to the axial gap type rotating electric machine 1 shown in Figure 1, a thrust force acts on the flange portion 7 of the core 20 in the direction toward the rotor 3 along the rotation axis 10 during the operation of the axial gap type rotating electric machine 1. If the teeth 6 and the flange portion 7 were independent members, there would be a risk of the flange portion 7 being displaced or detached from the teeth 6. In this example, since the flange portion 7 constitutes a first member 5 integrated with multiple teeth 6, it is not possible for the flange portion 7 to be displaced or detached from the teeth 6 even if a thrust force acts on the flange portion 7. Furthermore, although the first member 5 is connected to the second member 9, the possibility of the second member 9 being displaced or detached from the second member 9 due to the thrust force is low. This is because, in the first member 5, which has a large mass due to the presence of multiple teeth 6, the thrust force per unit mass is small, making it difficult for the first member 5 to move due to the thrust force.

[0094] The core 20 in this example is constructed by combining one first member 5 and one second member 9. In other words, the core 20 can be completed simply by connecting the first member 5 and the second member 9. Therefore, the core 20 in this example is highly productive.

[0095] <Embodiment 2> In Embodiment 2, a configuration in which the first member 5 consists of a plurality of compacted molded bodies 50 will be described with reference to Figure 8. As shown in Figure 8, the first member 5 in this example is composed of six compacted molded bodies 50. Each compacted molded body 50 has two teeth 6 and an arc-shaped flange portion 7 that connects these teeth 6. By combining these compacted molded bodies 50 in an annular shape, the plurality of flange portions 7 are connected in an annular shape. In the state in which the plurality of first members 5 are connected in an annular shape, all the teeth 6 provided on these first members 5 are arranged at equal intervals in the direction along the annular shape.

[0096] Even with the configuration in this example, when a thrust force is applied to the flange 7 during the operation of the axial gap type rotating electric machine 1, the flange 7 does not displace or detach from the teeth 6. Furthermore, because the first member 5, which has two teeth 6, is heavy, even when a thrust force is applied to the flange 7, the first member 5 is unlikely to displace or detach from the second member 9.

[0097] <Embodiment 3> In Embodiment 3, an example of a core 20 in which the outer periphery shape of the first member 5 and the outer periphery shape of the second member 9 are the same will be described with reference to Figure 9. In Figure 9, the first member 5 and the second member 9 are shown side by side, one above the other. For the first member 5, the first surface S1 on which the teeth 6 are arranged is shown. For the second member 9, the third surface S3 is shown, which is arranged to face the first surface S1.

[0098] The flange portion 7 of the first member 5 in this example is provided with a plurality of outer peripheral notches 71. Each outer peripheral notch 71 is formed in a position sandwiched between the first teeth 61 and the second teeth 62. The second member 9, which is combined with the first member 5, is also provided with a plurality of outer peripheral notches 91. Since the outer peripheral shape of the first member 5 and the outer peripheral shape of the second member 9 are the same, the shape of the outer peripheral notches 71 and the shape of the outer peripheral notches 91 are also the same.

[0099] In this example, the inner circumferential shape of the first member 5 and the inner circumferential shape of the second member 9 are identical. In other words, in this example, the contour shape of the first member 5 when viewed from above is identical to the contour shape of the second member 9 when viewed from above.

[0100] When forming the core 20 using the first member 5 and the second member 9 described above, the first member 5 and the second member 9 are assembled such that the outer peripheral notches 71 and 91 coincide in a plan view.

[0101] According to the configuration of this example, a portion of the mold for compacting the first member 5 and the second member 9 can be shared. Figure 10 shows an example of a mold 100 for compacting the second member 9. The mold 100 comprises a die 101, an upper punch 102, a lower punch 103, and a core 104. The shapes of each component of the mold 100 are simplified and differ from the actual shapes. Multiple protrusions 101p are formed on the inner circumferential surface of the die 101 at equal intervals in the circumferential direction of the inner circumferential surface. The upper punch 102 and the lower punch 103 have notches formed to accommodate the protrusions 101p during compaction. The second member 9 is formed by filling the cavity 100c formed inside the mold 100 with raw material powder and compressing the raw material powder with the lower punch 103 and the upper punch 102. In this example, protrusions 101p are formed on the inner circumferential surface of the die 101. The shape of this projection 101p is transferred, forming the outer circumference notch 91 of the second member 9.

[0102] When compacting a first member 5, whose contour shape in plan view is the same as that of the second member 9, only at least one of the upper punch 102 and lower punch 103 in the mold 100 needs to be changed. In other words, the die 101 and core 104 in the mold 100 can be shared between the first member 5 and the second member 9. In this example, only the upper punch 102 is changed between the first member 5 and the second member 9, and the die 101, lower punch 103, and core 104 are shared. When compacting the first member 5 and the second member 9 on the same production line, there is no need to change the die 101 and core 104. Even when compacting the first member 5 and the second member 9 on different production lines, there is no need to change the design of the die 101 and core 104 used on each production line, and the die 101 and core 104 can be easily manufactured.

[0103] Unlike this example, when compacting a first member 5 having an inner circumference notch 72 as shown in Figure 4, and a second member 9 having an inner circumference notch of the same shape and size as the first member 5, the projection for forming the inner circumference notch 72 can be formed on the core 104.

[0104] <Embodiment 4> In Embodiment 4, an example of a core 20 in which the shape of the second member 9 differs from that of Embodiment 3 will be described with reference to Figure 11. The way to read Figure 11 is the same as in Figure 9.

[0105] The second member 9 in this example has a slit 92 that extends straight from the outer peripheral edge 9X of the annular-shaped second member 9 toward the central axis of the second member 9 and connects to the through hole 90. The center line of the slit 92 along the length direction of the slit 92 extending from the outer peripheral edge 9X toward the central axis passes through the area centroid of the through hole 90. The shape of this slit 92 matches the shape of the portion of a predetermined length from the outer peripheral edge 7X in the outer peripheral notch 71 of the first member 5. When compacting such a second member 9, the die 101 used for compacting the first member 5 can be used.

[0106] In this example as well, the core 20 can be formed by fitting the teeth 6 of the first member 5 into the through hole 90 of the second member 9.

[0107] 1 Rotating electric machine 10 Rotating shaft, 10A First end, 10B Second end 11 First bearing, 12 Second bearing 2 Stator 20 Core, 25 Coil 3 Rotor 30 Rotor back yoke, 32 Magnet 4 Case 4S Inner surface 4c Counterbore, 4h Through hole 40 Case body, 41 Cover, 45, 49 Screw 5 First component 50 Compacted molded body 6 Teeth 6a First end face, 6b Second end face 6A First end, 6B Second end 60 Screw hole 61 First tooth, 62 Second tooth 7 Flange 7c Central axis, 7r, 7r1, 7r2 Radial direction 7R Region, 7X Outer circumference, 7Y Inner circumference 70 Small cross section 71 Outer circumference notch, 72 Inner circumference notch, 73 Recess 8 Yoke 9 Second member 9X Outer edge 90 Through hole, 91 Outer notch, 92 Slit, 95 Insertion hole 100 Mold, 100c Cavity 101 Die, 101p Projection 102 Upper punch, 103 Lower punch, 104 Core D1 First direction, D2 Second direction Ly, Lt Length R1 Inner arc, R2 Outer arc, R3 First straight line, R4 Second straight line S1 First surface, S2 Second surface, S3 Third surface, S4 Fourth surface

Claims

1. A core for use in an axial gap type rotating electric machine, comprising: a first member; and a second member combined with the first member, wherein the first member is formed from at least one compacted body, the compacted body comprises: a plurality of columnar teeth; and a flange portion integrally connecting the first ends of the plurality of teeth, the flange portion having a first surface on which the plurality of teeth are arranged to protrude; and a second surface opposite to the first surface and facing the rotor used in the rotating electric machine, the outer shape of the flange portion when viewed from above the first surface being arc-shaped or annular-shaped, the plurality of teeth being arranged at equal intervals in a direction along the arc-shaped or annular-shaped, the second member having a third surface facing the first surface and a fourth surface opposite to the third surface, the outer shape of the second member when viewed from above the third surface being annular-shaped, and the second ends of each of the plurality of teeth being connected to the second member.

2. The core according to claim 1, wherein the first member is formed from a single compacted molded body, and the flange portion has the annular shape.

3. The core according to claim 1 or 2, wherein the plurality of teeth include adjacent first teeth and second teeth, and the flange portion has a small cross-sectional area in the region between the first teeth and the second teeth where the magnetic path cross-sectional area is locally small.

4. The core according to claim 3, wherein the small cross-section portion includes a line bisector that divides the distance between the first tooth and the second tooth.

5. The core according to claim 3 or 4, wherein the small cross-sectional portion includes an outer peripheral notch extending from the outer peripheral edge toward the inner peripheral edge of the flange portion.

6. The core according to any one of claims 3 to 5, wherein the small cross-sectional portion includes an inner circumferential notch extending from the inner circumferential edge toward the outer circumferential edge of the flange portion.

7. The core according to any one of claims 3 to 6, wherein the small cross-sectional portion includes a recess formed on at least one of the first surface and the second surface.

8. The core according to any one of claims 1 to 7, wherein the second member is a flange separate from the flange.

9. The core according to any one of claims 1 to 7, wherein the second member is a yoke.

10. The core according to any one of claims 1 to 9, wherein the second member has a recess or through hole into which the second end is fitted.

11. The core according to claim 10, wherein the second end does not protrude from the through hole to the fourth surface.

12. The core according to claim 11, wherein, in the thickness direction of the second member from the third surface toward the fourth surface, the length over which the through hole and the second end overlap is 90% or more of the length of the through hole.

13. The core according to any one of claims 10 to 12, wherein the variation in length from the fourth surface of the second member to the second surface of the flange portion is 0.05 mm or less.

14. The core according to any one of claims 1 to 13, wherein at least some of the multiple teeth have screw holes on the end faces of the second end.

15. The core according to claim 14, wherein the number of screw holes is less than the number of teeth.

16. The core according to claim 2, wherein the second member is formed from a powder compacted body different from the first member, and the outer circumferential shape of the flange portion and the outer circumferential shape of the second member are the same shape.

17. The core according to claim 2 or claim 16, wherein the second member is formed from a powder compacted body different from the first member, and the inner circumferential shape of the flange portion and the inner circumferential shape of the second member are the same shape.

18. A stator for use in an axial gap type rotating electric machine, comprising a core according to any one of claims 1 to 17, and coils arranged on each of the plurality of teeth.

19. A rotating electric machine comprising the stator described in claim 18.

Images