Stator core production method, stator core, and rotary electric machine

Abstract

To provide a technique capable of improving the productivity of a thermal treatment step for a stator core.SOLUTION: A stator core production method S110 is a production method for a stator core having a wire aggregate 42 which is a bundle of multiple soft magnetic wire materials 41. The method includes: a step (S114) of providing, at least one point on the wire aggregate 42 formed into a ring shape, a fixation point 45 where the soft magnetic wire materials 41 are fixed in a state of being in contact with each other; a step (S116) of performing heat treatment on the wire aggregate 42; and a step (S118) of cutting the wire aggregate 42 after the heat treatment step.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a stator core, a stator core, and a rotating electrical machine.

Background Art

[0002] A rotating electrical machine in which a rotor and a stator are arranged to face each other is known. For example, Patent Document 1 describes a rotating electrical machine including a rotor and a stator arranged to face each other in the axial direction with a gap therebetween. The stator includes a plurality of stator cores arranged in the circumferential direction and a plurality of coils wound around the periphery of each stator core. A soft magnetic wire is used for this stator core.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] From the viewpoint of improving the performance of a rotating electrical machine, it is important to perform heat treatment on the stator core, which is the iron core of the rotating electrical machine, in order to reduce the influence of processing strain of the stator core and improve magnetic properties. However, sufficient studies have not been made so far on the heat treatment of an iron core using a soft magnetic wire as in the rotating electrical machine described in Patent Document 1.

[0005] An object of the present invention is to provide a technology capable of improving the productivity of the heat treatment process of a stator core in view of such problems.

Means for Solving the Problems

[0006] In order to solve the above problems, a method for manufacturing a stator core according to an aspect of the present invention is a method for manufacturing a stator core having a wire assembly in which a plurality of soft magnetic wires are bundled, the method including: providing a fixed portion where the soft magnetic wires are fixed to each other in contact with each other at at least one location of the wire assembly formed in a ring shape; heat-treating the wire assembly; and cutting the wire assembly after the heat-treatment step.

[0007] Another aspect of the present invention is a stator core of a rotating electrical machine. This stator core is a stator core having a wire assembly in which a plurality of soft magnetic wires are formed in a ring shape, the wire assembly having been heat-treated, and an end portion of the wire assembly being plastically deformed with respect to another portion of the wire assembly.

[0008] Still another aspect of the present invention is a rotating electrical machine. This rotating electrical machine includes a stator core having a wire assembly in which a plurality of soft magnetic wires are formed in a ring shape. The wire assembly has been heat-treated, and an end portion of the wire assembly is plastically deformed with respect to another portion of the wire assembly.

[0009] In addition, any combination of the above-described components, or those obtained by mutually replacing the components and expressions of the present invention among methods, systems, etc., are also effective as aspects of the present invention.

Advantages of the Invention

[0010] According to the present invention, it is possible to provide a technique capable of improving the productivity of the heat-treatment step of the stator core.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Best Mode for Carrying Out the Invention

[0012] Hereinafter, the present invention will be described with reference to the drawings based on preferred embodiments. In the embodiments and variations, the same or equivalent components and members shall be denoted by the same reference numerals, and repeated explanations will be omitted as appropriate. Also, the dimensions of the members in each drawing are shown enlarged or reduced as appropriate for easy understanding. Further, some of the members that are not important for explaining the embodiments in each drawing are shown with omission.

[0013] Also, terms including ordinals such as first and second are used to describe various components, but this term is used only for the purpose of distinguishing one component from another, and the components are not limited by this term.

[0014] [Embodiment] With reference to FIGS. 1 and 2, the configuration of the rotating electrical machine 100 according to the embodiment will be described. In this specification, an electromechanical machine having a rotating part is referred to as a "rotating electrical machine", and the rotating electrical machine includes a motor, a generator, and a motor-generator. The rotating electrical machine 100 in this example can be used as a motor, a generator, or a motor-generator.

[0015] FIG. 1 is a side view schematically showing an example of the rotating electrical machine 100. The rotating electrical machine 100 includes a rotor 2 and a stator 4. The rotor 2 is provided so as to be rotatable about the rotation axis La. Hereinafter, the direction parallel to the rotation axis La is referred to as the axial direction (the vertical direction in the figure), the direction orthogonal to the rotation axis La in a plane orthogonal to the rotation axis La is referred to as the radial direction, and the circumferential direction of a circle centered on the rotation axis La is referred to as the "circumferential direction". In FIG. 1, the upper side may be referred to as "up", and the opposite side as "down". Such notation of directions does not limit the posture of the rotating electrical machine 100, and the rotating electrical machine 100 can be used in any posture.

[0016] In the example of FIG. 1, the rotating electrical machine 100 is an axial-gap type motor including a rotor 2 and a stator 4 that face each other with an air gap in the axial direction. The rotor 2 is rotatably supported about the rotation axis La by bearing means 28.

[0017] The rotor 2 has a rotor yoke 22, an annular magnet 24, and a shaft 12. The rotor yoke 22 is a disk made of soft magnetic material. The shaft 12 is a rod-shaped stainless steel member extending along the rotation axis La, passing through the center of the rotor yoke 22, and fixed to the rotor yoke 22.

[0018] The magnet 24 is fixed to the lower surface of the rotor yoke 22, for example, by adhesion. The magnet 24 has a plurality of magnetic poles 26 that function as drive magnetic poles on the surface facing the stator core 3 in the axial direction. For example, the plurality of magnetic poles 26 are ten magnetic poles arranged at predetermined intervals in the circumferential direction. As an example, the magnet 24 of the present embodiment is a neodymium magnet mainly composed of neodymium, iron, and boron. The magnet 24 supplies magnetic flux (hereinafter simply referred to as "magnetic flux F") from the magnetic poles 26 to the magnetic path of the stator core 3. For the magnetic poles 26, the side from which the arrow of the magnetic flux F exits is the N pole, and the side into which it enters is the S pole. The magnetic flux F outside the magnet 24 exits from the N pole on the lower surface of the magnet 24, passes from one end to the other end of the stator core 3, and enters the S pole on the lower surface of the magnet 24.

[0019] The stator support member 32 is a disk-shaped member having a side facing the magnet 24 and a side opposite thereto, and is made of a non-magnetic material. As this non-magnetic material, a resin material, a carbon material, a glass material, a non-magnetic metal material, a ceramic material, etc. can be adopted. Bearing means 28 is provided at the center of the stator support member 32, and the shaft 12 is inserted vertically into the bearing means 28. The bearing means 28 is a rolling bearing. With this configuration, the stator 4 can rotatably support the rotor 2.

[0020] Figure 2 is an exploded view showing the stator 4 unfolded. In Figure 2, for ease of understanding, the lengths of the teeth portions 33 described later are shown with different lengths for each phase. The stator 4 includes a stator support member 32, a plurality of stator cores 3, and a plurality of coils 8. In this embodiment, corresponding to each of the U-phase, V-phase, and W-phase, one stator core 3 and one coil 8 are provided for each phase. The coils 8 may be distributed and arranged at multiple locations. The U-phase coil 8-U is wound around the U-phase stator core 3, the V-phase coil 8-V is wound around the V-phase stator core 3, and the W-phase coil 8-W is wound around the W-phase stator core 3. In other words, the stator 4 in this example has three stator cores 3 and three coils 8. Note that in Figure 1, one stator core 3 and one coil 8 are shown.

[0021] The stator core 3 functions as a magnetic path for allowing the magnetic flux F supplied from the magnetic pole 26 to pass through. The three stator cores 3 are fixed to the stator support member 32 using an adhesive at predetermined angles (e.g., 120°) in the circumferential direction.

[0022] The stator core 3 has two teeth portions 33 facing the magnetic pole 26 and a yoke portion 34 connecting the two teeth portions 33. The teeth portion 33 is sometimes referred to as a salient pole. The yoke portion 34 is a rod-shaped or plate-shaped portion connected to the two teeth portions 33 and extends substantially parallel to the stator support member 32. The magnetic flux F flows into one teeth portion 33, flows through the yoke portion 34, and flows out from the other teeth portion 33. The magnetic flux F mainly flows in the axial direction in the teeth portion 33 and flows in the intersecting direction intersecting the axial direction in the yoke portion 34. The coil 8 is arranged on the yoke portion 34. The portion of the yoke portion 34 where the coil 8 is arranged is called the arrangement portion 35.

[0023] The coil 8 includes three-phase coils 8-U, 8-V, and 8-W formed by winding a copper wire coated with a resin such as urethane around the outer circumference of the yoke portion 34. The three-phase coils 8-U, 8-V, and 8-W are, for example, three-phase star-connected.

[0024] The tooth portion 33 and the yoke portion 34 are configured to include a soft magnetic wire 41 wound a plurality of times. It may be formed of a single soft magnetic wire 41 or may be formed of a plurality of soft magnetic wires 41. At least a part of the plurality of soft magnetic wires 41 constituting the stator core 3 is continuous between the tooth portion 33 and the yoke portion 34. The stator core 3 can be configured by bundling a plurality of soft magnetic wires 41. By configuring with the soft magnetic wire 41, the stator core 3 can freely change the shape of the outer contour of the cross section cut along the plane orthogonal to the extending direction of the soft magnetic wire 41.

[0025] The soft magnetic wire 41 will be described. The soft magnetic wire 41 is a wire having soft magnetism and can contain a predetermined additive element in iron (Fe) as the main component from the viewpoint of obtaining desired magnetic properties. Examples of this additive element include carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), and the like. The soft magnetic wire 41 in this example contains 0.1 mass% to 6.0 mass% of silicon (Si) in iron (Fe) as the main component. The type and content rate of the additive element can be set by experiments or simulations according to the desired properties.

[0026] The soft magnetic wire 41 can be formed by stretching a material into a wire of a desired thickness by plastic working such as wire drawing. If the outer diameter of the soft magnetic wire 41 is too large, the eddy current loss increases, and if it is too small, the productivity decreases. The outer diameter of the soft magnetic wire 41 refers to the diameter of a circle circumscribing the outer surface of the cross section of the soft magnetic wire 41. From these, the outer diameter of the soft magnetic wire 41 can be set by experiments or simulations so as to obtain desired properties. The cross-sectional shape of the soft magnetic wire 41 may be circular, elliptical, polygonal, or the like. The outer surface of the soft magnetic wire 41 may be insulated from the viewpoint of reducing the eddy current loss. The soft magnetic wire 41 is subjected to a predetermined heat treatment after processing in order to reduce the processing strain.

[0027] The operation of the rotating electrical machine 100 configured as described above will be described. When the rotating electrical machine 100 is a motor, three-phase drive currents are supplied from a drive circuit (not shown) to the coils 8-U, 8-V, and 8-W of the coil 8, respectively. As a result, a rotating magnetic field is generated at the tip of the tooth portion 33, and a rotational torque is generated in the magnet 24 due to the interaction between this rotating magnetic field and the magnetic poles 26 of the magnet 24. Due to this rotational torque, the rotor 2 rotates together with the magnet 24.

[0028] When the rotating electrical machine 100 is a generator, when the rotor 2 rotates, the positional relationship between the magnetic poles 26 and the tips of the tooth portions 33 changes sequentially. As a result, the magnitude of the magnetic flux F supplied from the magnetic poles 26 to each phase of the stator core 3 changes in a sine wave shape, and three-phase alternating voltages are output from the coils 8-U, 8-V, and 8-W of the coil 8.

[0029] Next, with reference to FIGS. 3 and 4, a method for manufacturing the stator core 3 will be described. FIG. 3 is a flowchart schematically showing a manufacturing method S110 of the stator core 3. FIG. 4 is a process diagram schematically showing the manufacturing method S110 of the stator core 3.

[0030] In the manufacturing method S110, the stator core 3 is manufactured using a soft magnetic wire 41 that has been drawn to a desired thickness and whose outer surface is insulated. First, a wire aggregate 42 in which a plurality of soft magnetic wires 41 are formed in a ring shape is formed (step S112). In this step, one or a plurality of soft magnetic wires 41 are wound around a predetermined winding frame a predetermined number of times. The wire aggregate 42 is not particularly limited as long as it has a ring shape. Note that there is no limitation to a ring shape, and it is not limited to a substantially rectangular shape as shown in FIG. 4, and various shapes such as a circular shape or an elliptical shape may be used, for example. In this example, as shown in FIG. 4(A), the wire aggregate 42 has a substantially rectangular shape in which two horizontal side portions 43 and two vertical side portions 44 are connected by four arcs. The horizontal side portion 43 is a portion that becomes a yoke portion, and the vertical side portion 44 is a portion that becomes a tooth portion. The wire aggregate 42 may be referred to as a ring body.

[0031] Next, a fixing portion 45 is provided at at least one location of the wire assembly 42 where the soft magnetic wires 41 are in contact with each other and fixed to each other (step S114). The fixing portion 45 is formed such that the plurality of bundled soft magnetic wires 41 are in close contact with each other to the extent that they do not naturally unwind. For example, the fixing portion 45 can be formed by applying local pressure to a portion that becomes the fixing portion 45 of the bundle of the plurality of soft magnetic wires 41. At the fixing portion 45, the soft magnetic wires 41 may be plastically deformed.

[0032] There is no limit to the number of the fixing portions 45. In this example, as shown in FIG. 4(B), the fixing portions 45 are provided at positions that bisect the vertical width of the vertical side portions 44 at each of the two vertical side portions 44. Thus, the number of the fixing portions 45 may be 2, or may be 3 or more.

[0033] At the fixing portion 45, the plurality of soft magnetic wires 41 may be non-conductive with respect to each other. Even in this case, since the fixing portion 45 is provided at one or more locations of the wire assembly 42 and hardly unwinds naturally, handling in subsequent steps becomes easier.

[0034] The fixing portion 45 can include a short-circuit region 46 where the plurality of soft magnetic wires 41 are electrically short-circuited. For example, when forming the fixing portion 45, the short-circuit region 46 can be formed by bringing the plurality of soft magnetic wires 41 into closer contact with each other so that the insulation on the outer surface of the soft magnetic wires 41 is broken. The entire fixing portion 45 may be the short-circuit region 46, or a part of the fixing portion 45 may be the short-circuit region 46. Two or more fixing portions 45 including the short-circuit region 46 are arranged spaced apart from each other.

[0035] Next, the wire assembly 42 is heat-treated (step S116). By this heat treatment, it can be expected that the processing strain of the soft magnetic wires 41 is reduced and the magnetic characteristics of the wire assembly 42 are restored or improved. As long as the processing strain is reduced, there is no limit to the heat treatment method. In the embodiment, a so-called annealing treatment is performed in which the wire assembly 42 is held at a high temperature of 700°C or higher and 1000°C or lower for a predetermined time and then slowly cooled.

[0036] As a method for heating the wire assembly 42 in heat treatment, methods such as using a furnace such as an electric furnace, using electric current heating, using high-frequency induction heating, etc. can be adopted. When the fixed portion 45 does not include the short-circuit region 46, since an electrical loop is not closed within the wire assembly 42, a current cannot flow through the wire assembly 42, and as a result, electric current heating and induction heating cannot be applied. In this case, the wire assembly 42 can be heated and heat-treated by using a method of using a furnace.

[0037] It is desirable that the energy utilization efficiency is high. Therefore, in the embodiment, the wire assembly 42 is heated and heat-treated by a method of energizing the wire assembly 42 by energizing from the short-circuit region 46 or a method of inductively heating the wire assembly 42 using high frequency. In this case, it is advantageous in terms of higher energy utilization efficiency than the method of using a furnace. The wire assembly 42 is preferably heated in a container that can form a closed space, and this container may be a non-metal container or a container made of an electromagnetic steel sheet.

[0038] Specifically, the heat treatment in step S116 adopts a method of heating the wire assembly 42 by using Joule heat generated by passing a current through the wire assembly 42 through the short-circuit region 46. That is, a current is passed from one of the two short-circuit regions 46 to the other from an external power source (not shown) to generate Joule heat.

[0039] In addition, when the wire assembly 42 is heated in a coiled state by high-frequency induction heating or direct current energization, in principle, the current density is higher on the inner peripheral side, so the heating temperature is also higher. In this case, when comparing the metal structures in the cross-section of the wire assembly 42, differences occur in crystal grains, etc. between the inner peripheral side and the outer peripheral side. Therefore, by comparing crystal grains, etc. between the inner peripheral side and the outer peripheral side, it is possible to determine whether heating was performed using Joule heat or using a furnace.

[0040] Next, the wire assembly 42 after the heat treatment is cut (step S118). In this step, as shown in FIG. 4(D), at the fixed portion 45 where the vertical width of the vertical side portion 44 is bisected, the wire assembly 42 is cut into two halves. For cutting the wire assembly 42, a cutting method based on a known principle such as a method using high-pressure water, a method using a grindstone, or a method using wire cutting can be adopted. The end portions of the wire assembly 42 after cutting correspond to the fixed portion 45 and are strongly plastically deformed with respect to other portions of the wire assembly 42.

[0041] In the wire assembly 42 after cutting, the horizontal side portion 43 constitutes the yoke portion 34, and the cut vertical side portion 44 constitutes the teeth portion 33.

[0042] Next, a coil 8 is formed on the wire assembly 42 after cutting (step S120). In this step, as shown in FIG. 4(E), the coil 8 is formed by winding a copper wire coated with a resin such as urethane around the outer periphery of the yoke portion 34 of the wire assembly 42 after cutting.

[0043] If there is a short-circuit region 46, the eddy current loss may increase. Therefore, in the present embodiment, the short-circuit region 46 of the wire assembly 42 is removed (step S122). In this step, as shown in FIG. 4(F), after the coil is formed, the short-circuit region 46 is removed from the wire assembly 42 after cutting. The short-circuit region 46 can be removed by the same method as the cutting method described in step S118. Through these processes, the stator core 3 is manufactured. The stator core 3 is combined with other members to form the stator 4.

[0044] These processes are examples, and various modifications are possible. For example, the short-circuit region 46 may be removed after the heat treatment, and then the coil 8 may be formed.

[0045] The features of the manufacturing method S110 of the stator core 3 according to this embodiment will be described. The manufacturing method S110 is a method for manufacturing a stator core having a wire assembly 42 in which a plurality of soft magnetic wires 41 are formed in a ring shape, and includes a step (S114) of providing a fixed portion 45 where the soft magnetic wires 41 are fixed to each other in contact with each other at at least one location of the wire assembly 42, a step (S116) of heat-treating the wire assembly 42, and a step (S118) of cutting the wire assembly 42 after the heat-treatment step.

[0046] According to this method, by performing heat treatment after forming the fixed portion 45, the problem that the plurality of soft magnetic wires 41 are inadvertently loosened during the heat treatment hardly occurs, so the defect rate in the heat treatment step is reduced and the productivity is increased.

[0047] The examples of the embodiments of the present invention have been described in detail above. The above-described embodiments are merely specific examples for implementing the present invention. The content of the embodiments does not limit the technical scope of the present invention, and many design changes such as changes, additions, and deletions of components are possible without departing from the idea of the invention defined in the claims. In the above-described embodiments, regarding the content for which such design changes are possible, descriptions have been made with notations such as "in the embodiment" and "in the embodiment", but design changes are also allowed for the content without such notations. Also, the hatching in the drawings does not limit the material of the object with hatching.

[0048] (Modification example) Hereinafter, a modification example will be described. In the drawings and descriptions of the modification example, the same reference numerals are given to the same or equivalent components and members as those in the embodiment. Descriptions overlapping with those in the embodiment are omitted as appropriate, and the configurations different from those in the embodiment will be mainly described.

[0049] In the above description, an example in which all the fixed portions 45 include the short-circuit region 46 has been shown, but the present invention is not limited to this. The stator core may have a fixed portion that does not include a short-circuit region. For example, fixed portions including short-circuit regions may be provided on two longitudinal side portions, and fixed portions not including short-circuit regions may be provided on two transverse side portions. In this case, the unintentional loosening of the wire assembly can be further reduced.

[0050] In the above description, an example in which the coil 8 is arranged in the yoke portion 34 has been shown, but the present invention is not limited to this. For example, part or all of the coil may be arranged in the tooth portion.

[0051] In the above description, an example in which the wire assembly 42 is heated by energization heating has been shown, but the present invention is not limited to this. For example, in heat treatment, heating using a furnace in energization heating and high-frequency induction heating may be used in combination, or heating using a furnace in high-frequency induction heating may be used in combination.

[0052] In the above description, an example in which the rotating electrical machine 100 includes one rotor 2 and one stator 4 has been shown, but the present invention is not limited to this. For example, the rotating electrical machine may include a plurality of rotors, or the rotating electrical machine may include a plurality of stators, or the rotating electrical machine may include a plurality of rotors and a plurality of stators.

[0053] In the above description, an example in which the rotating electrical machine 100 includes three stator cores 3 has been shown, but the present invention is not limited to this. For example, the number of stator cores 3 may be an integer multiple of 3 such as 6, 9, 12, etc. In this case, the number of magnetic poles 26 may be changed according to the number of stator cores 3.

[0054] In the above description, an example in which the rotating electrical machine 100 is an axial-gap type rotating electrical machine has been shown, but the present invention is not limited to this. For example, the rotating electrical machine may be a radial-gap type rotating electrical machine.

[0055] In the above description, an example in which the magnet 24 is an annular member surrounding the rotation axis La has been shown, but the present invention is not limited to this. For example, the magnet may be a segment magnet divided for each drive pole. As the shape of the segment magnet, a circular shape, an elliptical shape, a trapezoidal shape, a fan shape, etc. can be adopted.

[0056] In the above description, an example in which the magnet 24 is a neodymium magnet has been shown, but the present invention is not limited to this. For example, the magnet may be a rare earth magnet mainly composed of a rare earth element different from neodymium, a ferrite magnet, or a plastic magnet.

[0057] In the above description, an example in which the stator support member 32 is made of a non-magnetic material has been shown, but the present invention is not limited to this. For example, the stator support member may include a soft magnetic material such as an electromagnetic steel sheet.

[0058] In the above description, an example in which the bearing means 28 is a rolling bearing has been shown, but the present invention is not limited to this. For example, the bearing means may be a sliding bearing such as an oil-impregnated metal bearing.

[0059] Each of these modifications has the same actions and effects as the embodiment.

[0060] Any combination of the above-described embodiment and the modifications is also useful as an embodiment of the present invention. The new embodiment resulting from the combination has the combined effects of the embodiments and modifications combined.

Description of Reference Numerals

[0061] 2 Rotor, 3 Stator core, 4 Stator, 8 Coil, 24 Magnet, 26 Pole, 33 Tooth portion, 34 Yoke portion, 41 Soft magnetic wire, 45 Fixed portion, 46 Short-circuit region, 100 Rotating electrical machine.

Claims

1. A method for manufacturing a stator core having a wire assembly in which a plurality of soft magnetic wires are bundled, comprising: providing a fixed portion where the soft magnetic wires are fixed to each other in contact with each other at at least one location of the wire assembly formed in a ring shape; performing a heat treatment on the wire assembly; cutting the wire assembly after the heat treatment step; A manufacturing method including the above steps.

2. The fixed portion includes a short-circuit region where the soft magnetic wires are electrically short-circuited, The manufacturing method according to claim 1, wherein the short-circuit region is removed after the heat treatment step.

3. The manufacturing method according to claim 2, wherein after cutting the wire assembly and before removing the short-circuit region, an electric wire is wound around the wire assembly to form a coil.

4. The fixed portion has a short-circuit region where the soft magnetic wires are electrically short-circuited to each other, and includes two fixed portions arranged apart from each other, In the heat treatment step, the wire assembly is heated using Joule heat generated by passing an electric current through the wire assembly through the short-circuit region. The manufacturing method according to claim 1.

5. The fixed portion includes a short-circuit region where the soft magnetic wires are electrically short-circuited to each other, In the heat treatment step, the wire assembly is heated using high-frequency induction heating. The manufacturing method according to claim 1.

6. A stator core having a wire assembly in which a plurality of soft magnetic wires are formed in a ring shape, The wire assembly has been heat-treated, and an end portion of the wire assembly is plastically deformed with respect to other portions of the wire assembly.

7. A rotating electrical machine including a stator core having a wire assembly in which a plurality of soft magnetic wires are formed in a ring shape, The wire assembly has been heat-treated, and an end portion of the wire assembly is plastically deformed with respect to other portions of the wire assembly.

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