Electric motor and method for manufacturing armature constituting said electric motor

Abstract

An electric motor (10) is provided with: an armature (14) provided with an iron core (26) and an armature coil (24) provided so as to surround the iron core (26); and a movable element (12) disposed so as to face the armature (14). The iron core (26) is configured to include a plurality of U-shaped members (28) and a plurality of U-shaped members (30) perpendicular to the U-shaped members (28). The U-shaped members (28) and the U-shaped members (30) each have a U-shape comprising a pair of side parts (42) that are parallel or substantially parallel to each other and an intermediate part that connects the pair of side parts. The side parts constitute the teeth part of the iron core (26), and the intermediate part constitutes the yoke part of the iron core (26).

Description

Electric motor and method of manufacturing an armature constituting said electric motor

[0001] The present invention relates to an electric motor having a magnetic path through which magnetic flux flows three-dimensionally, and a method for manufacturing an armature that constitutes the electric motor.

[0002] Electric motors are known that include an armature having an armature coil and an iron core, and a mover that faces the armature. In conventional electric motors, magnetic flux flows planarly, for example, along the moving direction. However, electric motors have been proposed that have a three-dimensional magnetic pole structure in which magnetic flux flows not only in the moving direction but also in a direction intersecting the moving direction. For example, the electric motor described in Patent Document 1 is such an example. In the electric motor described in Patent Document 1, magnetic flux emitted from the open side of the magnetic pole block is configured to branch into the moving direction and a direction intersecting the moving direction.

[0003] Patent No. 6835692

[0004] Incidentally, in an electric motor having a structure in which magnetic flux flows three-dimensionally (three-dimensional magnetic pole structure) as described in Patent Document 1, it is required to form a magnetic path that realizes this, but a structure and manufacturing method suitable for this have not been proposed.

[0005] An object of the present invention is to provide an electric motor having a structure suitable for forming a magnetic path through which magnetic flux flows three-dimensionally, and a method for manufacturing an armature that constitutes the electric motor.

[0006] In order to solve the above-mentioned problems, one embodiment of the present invention provides an electric motor comprising: an armature having an iron core and an armature coil arranged to surround the iron core; and a mover arranged opposite the armature, wherein the iron core of the armature is composed of a plurality of members made of electromagnetic steel pieces, each of the plurality of members having a U-shape consisting of a pair of side portions that are parallel or approximately parallel to each other and a middle portion connecting the pair of side portions, and the plurality of members including a plurality of first members and a plurality of second members whose middle portions are perpendicular to the longitudinal direction of the middle portions of the first members, and the middle portions of the first members and the middle portions of the second members each constitute yoke portions of the iron core, and the side portions of the first members and the side portions of the second members each constitute teeth portions of the iron core.

[0007] According to one aspect of the present invention, a method for manufacturing an armature that constitutes an electric motor includes a first step of molding a plurality of first members and a plurality of second members, respectively; a second step of molding a plurality of blocks in which the plurality of first members and the plurality of second members are fixed in predetermined numbers, respectively; and a third step of connecting the plurality of blocks to each other to form a holding member.

[0008] According to yet another aspect of the present invention, a method for manufacturing an armature that constitutes an electric motor includes a first step of molding a plurality of first members and a plurality of second members, and a second step of inserting each side portion of the plurality of first members and each side portion of the plurality of second members into an insertion hole of a holding member.

[0009] FIG. 1 is a perspective view illustrating an overview of an electric motor according to an embodiment of the present invention. FIG. 2 is an enlarged view of a portion of the electric motor of FIG. 1 in the direction of rotation. FIG. 3 is an enlarged view of an upper portion of FIG. 2 with the armature coil removed. FIG. 4 is a view of FIG. 3 as viewed in the direction of rotation along the axis of rotation. FIG. 5 is a view of FIG. 3 as viewed in the direction of rotation. FIG. 6 is a view illustrating a state in which the sides of a U-shaped member are bent. FIG. 7 is a view illustrating the U-shaped member of FIG. 6 in an assembled state. FIG. 8 is a view illustrating a method for manufacturing a U-shaped member. FIG. 9A is another view illustrating a method for manufacturing a U-shaped member, illustrating the state of the U-shaped member before it is formed. FIG. 9B is yet another view illustrating a method for manufacturing a U-shaped member, illustrating the state of the U-shaped member after it has been formed. FIG. 10A is yet another view illustrating a method for manufacturing a U-shaped member, illustrating the state of the U-shaped member before it is formed. FIG. 10B is yet another view illustrating a method for manufacturing a U-shaped member, illustrating the state of the U-shaped member after it has been formed. FIG. 11 is a diagram showing an embodiment in which a holding member is used as one embodiment of a fixing structure for a U-shaped member. FIG. 12A is a diagram showing a process of inserting a U-shaped member into an armature coil, showing the state immediately before insertion of the U-shaped member into the armature coil. FIG. 12B is another diagram showing the process of inserting a U-shaped member into an armature coil, showing the state after insertion of the U-shaped member into the armature coil. FIG. 13A is a diagram showing an embodiment of a block forming the holding member, showing a top view of the block. FIG. 13B is another diagram showing an embodiment of a block forming the holding member, showing a side view of the block. FIG. 14A is a diagram explaining a fixing structure for a U-shaped member using a holding member, showing the state before insertion of the U-shaped member into the holding member. FIG. 14B is another diagram explaining a fixing structure for a U-shaped member using a holding member, showing the state after insertion of the U-shaped member into the holding member. FIG. 14C is yet another diagram explaining a fixing structure for a U-shaped member using a holding member, showing the state in which the U-shaped members have been inserted into all of the insertion holes of the holding member. Fig. 15 is a flowchart illustrating a manufacturing process for an armature made of a U-shaped member. Fig. 16 is a flowchart illustrating another embodiment of a manufacturing process for an armature made of a U-shaped member.

[0010] [Overall Structure of Electric Motor] A preferred embodiment of the present invention will now be described with reference to the drawings. Fig. 1 is a perspective view illustrating an outline of an electric motor 10 according to one embodiment of the present invention. Fig. 2 is an enlarged view of a portion of the electric motor 10 in Fig. 1 in the direction of rotation.

[0011] The electric motor 10 includes a mover 12 (also referred to as a rotor) and an armature 14 (also referred to as a stator) arranged on the outer periphery of the mover 12. The electric motor 10 of this embodiment is a radial gap type electric motor in which the mover 12 is rotatably arranged inside the armature 14. The mover 12 and the armature 14 are arranged opposite each other in the radial direction, and a radial gap is formed between the mover 12 and the armature 14.

[0012] The mover 12 is formed in an annular shape and is configured to be rotatable about a rotation axis CL of a rotation shaft (output shaft) (not shown) that rotates together with the mover 12 .

[0013] The mover 12 includes a plurality of magnetic pole blocks 16 and a back yoke 18. Each of the plurality of magnetic pole blocks 16 includes an iron core 20 (rotor core) disposed opposite the armature 14, and a plurality of permanent magnets 22A to 22C surrounding the iron core 20 with the surface facing the armature 14 open.

[0014] The multiple permanent magnets 22A to 22C that make up the magnetic pole block 16 are arranged with the same magnetic poles facing the iron core 20. Adjacent magnetic pole blocks 16 are connected such that one surface of the permanent magnets 22A to 22C is in contact with one another. The back yoke 18 is an annular member made of, for example, a soft magnetic material. The multiple magnetic pole blocks 16 are arranged on the outer periphery of the back yoke 18 so as to be adjacent to each other in the rotational direction (circumferential direction).

[0015] The armature 14 is formed in an overall annular shape and is fixed so as not to rotate by being connected to a case (not shown), etc. The armature 14 includes a plurality of armature coils 24 and an iron core 26 (stator core).

[0016] Each of the multiple armature coils 24 has a frame shape with a frame hole 25 (see FIG. 12 ) formed therein. The armature coils 24 have a rectangular parallelepiped outer shape, and their longitudinal sides are arranged along the direction of the rotation axis CL (hereinafter referred to as the axial direction). The multiple armature coils 24 are arranged side by side in the rotation direction and in series in the axial direction.

[0017] The iron core 26 includes a plurality of U-shaped members 28 and a plurality of U-shaped members 30A-30C (hereinafter, referred to as U-shaped members 30 when not distinguished). Specifically, each of the plurality of U-shaped members 28 includes a pair of parallel (or substantially parallel) side portions 42 and an intermediate portion 44 connecting the pair of side portions 42 (see FIG. 4). Each of the plurality of U-shaped members 30A-30C includes a pair of parallel (or substantially parallel) side portions 46A-46C (side portions 46 when not distinguished) and an intermediate portion 48A-48C (intermediate portion 48 when not distinguished) connecting the pair of side portions 46A-46C (see FIG. 5). The U-shaped members 28 and 30 are each formed from a wire 32 (see FIG. 8) made of electromagnetic steel pieces. The U-shaped member 28 corresponds to the "first member" in the present invention, and the U-shaped members 30A to 30C correspond to the "second member" in the present invention.

[0018] U-shaped member 30 is disposed in a perpendicular position to U-shaped member 28. That is, the longitudinal direction of middle portion 44 of U-shaped member 28 is perpendicular to the longitudinal directions of middle portions 48A to 48C of U-shaped members 30A to 30C.

[0019] A pair of side portions 42 of each U-shaped member 28 is inserted into the frame holes 25 formed in each armature coil 24 so as to straddle adjacent armature coils 24 in the rotational direction. Also, a pair of side portions 46A to 46C of each U-shaped member 30 is inserted into the frame holes 25 formed in each armature coil 24 so as to straddle the armature coils 24 arranged in series (two rows) in the axial direction.

[0020] Fig. 3 is an enlarged view of the upper part of Fig. 2 with the armature coil 24 removed. Fig. 4 is a view of Fig. 3 as seen from the direction along the axis of rotation, and Fig. 5 is a view of Fig. 3 as seen in the direction of rotation. The arrows shown in Figs. 3 to 5 indicate the flow of magnetic flux when the armature coil 24 (omitted in Figs. 3 to 5) is energized.

[0021] 3 to 5, the multiple U-shaped members 28 are arranged such that the intermediate portions 44 are aligned along the rotational direction of the armature 14. The U-shaped members 28 are also arranged at equal angular intervals in the rotational direction, and are stacked in the axial direction.

[0022] The U-shaped members 30A to 30C have intermediate portions 48A to 48C arranged along the rotation axis CL. Each of the U-shaped members 30A to 30C has a pair of side portions 46A to 46C that overlap with a pair of side portions 46A to 46C of an adjacent U-shaped member 30A to 30C in the axial direction, and the intermediate portions 48A to 48C that overlap with the intermediate portions 48A to 48C of an adjacent U-shaped member 30A to 30C in the radial direction about the rotation axis CL.

[0023] Specifically, in the U-shaped member 30A, the pair of side portions 46A are positioned axially innermost, and the middle portion 48A is positioned radially innermost. In the U-shaped member 30B, the pair of side portions 46B are positioned axially outwardly of the pair of side portions 46A of the U-shaped member 30A, and the middle portion 48B is positioned radially outwardly of the middle portion 48A of the U-shaped member 30A. In the U-shaped member 30C, the pair of side portions 46C are positioned axially outwardly of the pair of side portions 46B of the U-shaped member 30B, and the middle portion 48C is positioned radially outwardly of the middle portion 48B of the U-shaped member 30B. That is, among the multiple U-shaped members 30A to 30C, the pair of side portions 46C of the U-shaped member 30C are positioned outermost in the axial direction, and the middle portion 48C is positioned outermost in the radial direction.

[0024] In an assembled state, each side portion 42, 46A to 46C of each U-shaped member 28, 30 has a tip that faces the mover 12 and is surrounded by the armature coil 24. These side portions 42, 46 form teeth portions in the iron core 26 (stator core) that are surrounded by the armature coil 24. Furthermore, each intermediate portion 44, 48A to 48C of the U-shaped members 28, 30 forms a yoke portion that connects a pair of side portions 42, 46A to 46C in the iron core 26 (stator core).

[0025] When the armature coil 24 of the armature 14 configured as described above is energized, a magnetic path is formed through which magnetic flux flows three-dimensionally. That is, as shown by the arrows in Figures 3 to 5, the magnetic flux flows radially through the teeth (side portions 42, 46A to 46C) of each U-shaped member 28, 30. Furthermore, the magnetic flux that moves radially not only flows in one direction and the other in the rotational direction along the intermediate portion 44 (yoke portion) of the U-shaped member 28, but also branches in the axial direction along the intermediate portion 48 (yoke portion) of the U-shaped member 30. This forms a magnetic path through which magnetic flux flows three-dimensionally.

[0026] Here, a shorter magnetic flux path requires less total amount of wire 32. Furthermore, because loss when magnetic flux changes over time depends on the volume of iron core 26 through which the magnetic flux passes, a shorter path reduces loss. For these reasons, it is desirable for the magnetic flux path to be connected along the shortest route. Therefore, a U-shaped member 30 stacked in the direction in which magnetic flux flows axially is disposed at the axial center of iron core 26 of armature 14, and U-shaped members 28 stacked in the direction in which magnetic flux flows rotationally are disposed on both sides of U-shaped member 30 in the axial direction of armature 14. Furthermore, U-shaped member 30 has a nested structure in which three U-shaped members 30A to 30C of different sizes are arranged so as to overlap without any gaps, thereby shortening the magnetic flux path.

[0027] Furthermore, the cross sections of the U-shaped members 28, 30 are formed to be quadrangular (angled). By forming the cross sections of the U-shaped members 28, 30 to be quadrangular, the teeth and yokes can be formed densely when the U-shaped members 28, 30 are stacked. In other words, the cross-sectional areas of the teeth and yokes in the U-shaped members 28, 30 through which magnetic flux passes can be maximized.

[0028] The surfaces of the U-shaped members 28, 30 are each coated with an insulating film. The insulating film on the surfaces of the U-shaped members 28, 30 prevents electrical conduction between adjacent U-shaped members 28, 30. If electrical conduction occurs between adjacent U-shaped members 28, 30, eddy currents will be generated, increasing loss. Even if electrical conduction occurs between adjacent U-shaped members 28, 30, contact resistance can reduce the generation of eddy currents compared to when the entire core is constructed from a single iron block. Furthermore, in order to sufficiently reduce loss due to eddy currents, it is preferable to coat the surfaces of the U-shaped members 28, 30 with an insulating film. By sufficiently reducing loss due to eddy currents, the electric motor 10 can be used effectively for high-speed drive applications.

[0029] 5 and other figures, because the intermediate portions 48A to 48C (yoke portions) of the U-shaped members 30A to 30C are arranged so as to be stacked in the radial direction, there is a risk that the intermediate portions 48A to 48C will protrude in the radial direction, thereby increasing the radial size of the armature 14. In contrast, as shown in Figures 6 and 7, the intermediate portion 48C of the U-shaped member 30C, in which a pair of side portions 46C (teeth portions) are located at both ends in the axial direction, is bent in the rotational direction relative to the pair of side portions 46C, thereby preventing the intermediate portion 48C from protruding in the radial direction.

[0030] 6 shows the shape before bending, and the U-shaped member 30C-2 on the right side shows the shape after bending. As shown in Fig. 6, the U-shaped member 30C-2 on the right side has an intermediate portion 48C bent at a substantially right angle (90 degrees) to a pair of side portions 46C that form the teeth.

[0031] 7 shows a state in which a U-shaped member 30C-2 in which an intermediate portion 48C is bent relative to a pair of side portions 46C (teeth portions) is assembled to the armature 14. Note that FIG. 7 also shows a U-shaped member 30C-1 in which the intermediate portion 48C is not bent relative to the pair of side portions 46C. In the U-shaped member 30C-2 shown in FIG. 7, the intermediate portion 48C is bent in the rotational direction relative to the pair of side portions 46C (teeth portions), so that the intermediate portion 48C (yoke portion) is positioned radially inward compared to the intermediate portion 48C of the U-shaped member 30C-1. As a result, the intermediate portion 48C does not protrude radially, and an increase in the radial size of the armature 14 is avoided.

[0032] 7, the intermediate portion 48C is bent at a substantially right angle (90 degrees) relative to the side portion 46C (tooth portion), but the angle of bending can be freely adjusted within a range from 0 degrees to 90 degrees as long as interference with the adjacent U-shaped members 28, 30 can be avoided after assembly. Also, by appropriately bending not only the U-shaped member 30C but also the U-shaped members 30A, 30B, an increase in the radial size of the armature 14 can be further avoided.

[0033] [Method for Manufacturing U-Shaped Members] Generally, the size of electric motors varies depending on the application, but manufacturing dedicated parts for each different sized electric motor is not easy from the perspective of mass production. Furthermore, the size of the electric motor that can be manufactured also depends on the size of the manufacturing equipment. Therefore, for large electric motors that exceed the manufacturing equipment, it is desirable to manufacture the iron core in sections and then assemble them. That is, when manufacturing the iron core 26 of this embodiment, multiple U-shaped members 28, 30 are manufactured, and by assembling these U-shaped members 28, 30, it is possible to manufacture an iron core 26 of any size.

[0034] The following describes a manufacturing method for the U-shaped members 28 and 30. FIG. 8 is a diagram illustrating a manufacturing method for the U-shaped members 28 and 30. Both U-shaped members 28 and 30 are formed from a common wire rod 32. The wire rod 32 is bent at bending position A shown on the left in FIG. 8 and the excess portion indicated by the dashed line is cut off to form an L-shaped member 35A shown in the upper right of FIG. 8 . The wire rod 32 is also bent at bending position B shown on the left in FIG. 8 and the excess portion indicated by the dashed line is cut off to form an L-shaped member 35B shown in the lower right of FIG. 8 . Next, the ends of a pair of L-shaped members 35A are joined together while abutting against each other to form a U-shaped member having a predetermined dimension. Similarly, the ends of a pair of L-shaped members 35B are joined together while abutting against each other to form a U-shaped member having a different dimension from the one shown in the upper right of FIG. 8 . By forming a U-shaped member from a pair of L-shaped members in this way, even large U-shaped members can be manufactured.

[0035] As described above, by adjusting the bending position of the wire rod 32, U-shaped members of any desired dimensions can be formed from the common wire rod 32. For example, in this embodiment, the U-shaped members 28, 30A, 30B, and 30C each have different dimensions. In contrast, by adjusting the bending position of the wire rod 32 and forming L-shaped members of different dimensions, these U-shaped members 28 and 30 can be formed from the common wire rod 32.

[0036] Furthermore, since there is a concern that a gap formed at the joint between a pair of L-shaped members will increase magnetic resistance, it is desirable to have a structure in which the members are in contact with each other without any gaps at the joint, ensuring strength even after joining and preventing, for example, misalignment in the shear direction.In contrast to this, a structure may be used in which a stepped or uneven shape is formed at the ends of adjacent L-shaped members in the stacking direction, and a stepped or uneven shape is also formed at the end of the L-shaped member to be joined to these, so that when the L-shaped members are joined to each other to form a U-shaped member, the stepped or uneven shapes formed on each member fit together, thereby ensuring the strength of the joint.

[0037] 9A shows an aspect in which a stepped shape 34 is formed by two L-shaped members 35X and 35Y adjacent to each other in the stacking direction, and FIG. 9B shows a state in which the L-shaped members 35X and 35Y of FIG. 9A are joined together.

[0038] As shown on the left side of FIG. 9A , two L-shaped members 35X and 35Y of different lengths overlap to form a stepped shape 34. Similarly, on the right side of FIG. 9A , two L-shaped members 35X and 35Y of different lengths overlap to form a stepped shape 34. The L-shaped members 35X and 35Y, which have different dimensions, are arranged to be joined. When the L-shaped members 35X and 35Y facing each other in the left-right direction are joined from the state shown in FIG. 9A , the state shown in FIG. 9B is obtained. At this time, the stepped shapes 34 formed on both the left and right sides fit together, and each joint is adjacent to the L-shaped members 35X and 35Y, making the joint less likely to shift in the shear direction.

[0039] FIG. 10A shows an aspect in which the uneven shape 36 is formed by three or more L-shaped members 35X, 35Y adjacent to each other in the stacking direction, and FIG. 10B shows a state in which the L-shaped members 35X, 35Y of FIG. 10A are joined together.

[0040] As shown on the left side of FIG. 10A , three or more L-shaped members 35X and 35Y of different lengths are alternately stacked in the stacking direction, forming a concave-convex shape 36. Similarly, on the right side of FIG. 10A , three or more L-shaped members 35X and 35Y of different lengths are alternately stacked in the stacking direction, forming a concave-convex shape 36. In FIG. 10A , the concave-convex shapes 36 facing each other are formed so that their concave and convex portions are opposite each other. That is, the L-shaped members 35X and 35Y are arranged to be joined. When the opposing L-shaped members 35X and 35Y are joined together from the state shown in FIG. 10A , the state shown in FIG. 10B is achieved. At this time, the concave-convex shapes 36 formed on both the left and right sides fit together, and each joint is adjacent to the L-shaped members 35X and 35Y, making the joint less likely to shift in the shear direction.

[0041] [Method of Fixing the Iron Core] Next, a method of fixing the U-shaped members 28, 30 will be described. The iron core 26 of the armature 14 is composed of multiple U-shaped members 28, 30 assembled together, and a structure for holding these members is required. Furthermore, in the electric motor 10 of this embodiment, magnetic flux flows in two directions, the rotational direction and the axial direction, so the cross-sectional area in each direction is small. As a result, the intermediate portions 44, 48 (yoke portions) of the U-shaped members 28, 30 are thin. Therefore, a structure that suppresses deformation of the iron core 26 of the armature 14 due to electromagnetic forces generated when the electric motor 10 is driven is desirable. To address this, the entire intermediate portion (entire yoke portion) of each U-shaped member 28, 30 is held from the radially outer side by a holding member 40, which will be described later, thereby fixing the entire iron core 26 of the armature 14.

[0042] 11 is a diagram showing an embodiment in which a retaining member 40 is used as one embodiment of a fixing structure for fixing the U-shaped members 28, 30, and is a view of a portion of the electric motor 10 in the direction of the rotation axis. As shown in Fig. 11, the intermediate portions 44, 48 (yoke portions) of the U-shaped members 28, 30 are covered with the annular retaining member 40, and the entire yoke portion is held by the retaining member 40. As a result, the U-shaped members 28, 30 are held by the retaining member 40, and deformation of the iron core 26 is also suppressed by the retaining member 40.

[0043] The holding member 40 is preferably made of resin. Resin has the characteristics of being insulating and lightweight. Because the holding member 40 is located close to the armature coil 24, through which current flows when the electric motor 10 is driven, there is a risk of the holding member 40 coming into contact with the armature coil 24. In contrast, by making the holding member 40 from an insulating resin, the holding member 40 is not affected even if it comes into contact with the armature coil 24. Furthermore, by making the holding member 40 from a lightweight resin, it is possible to suppress an increase in the weight of the electric motor 10.

[0044] Incidentally, insulating paper 45 is interposed between the armature coil 24 and the side portions 42, 46 (teeth portions) of the U-shaped members 28, 30 to prevent current flow between the armature coil 24 and the U-shaped members 28, 30. Fig. 12A shows the state immediately before the side portions 42, 46 of a pair of adjacent U-shaped members 28, 30 are inserted into the frame hole 25 of the armature coil 24, and Fig. 12B shows the state after the side portions 42, 46 of the pair of U-shaped members 28, 30 have been inserted into the frame hole 25 of the armature coil 24. As shown in Fig. 12A, insulating paper 45 has been inserted into the frame hole 25 of the armature coil 24 beforehand, and the side portions 42, 46 of the U-shaped members 28, 30 are inserted into the frame hole 25 from this state.

[0045] Here, when each U-shaped member 28, 30 is fixed by a holding member 40, as shown in Figure 12, the holding member 40 is located on the side of the middle portions 44, 48 (yoke portions) of the U-shaped members 28, 30 that are closest to the armature coil 24. If this holding member 40 interferes with the insulating paper 45, there is a risk that the insulating paper 45 will not be able to properly insulate the armature coil 24 from the side portions 42, 46 of the U-shaped members 28, 30. If the insulation is insufficient, when a leakage current occurs in the armature coil 24, the current will not pass through the expected path, reducing the current involved in magnetic interaction, which will result in a decrease in electromagnetic force and may also have adverse effects on other equipment.

[0046] To prevent this, the holding member 40 covering the U-shaped members 28, 30 has spaces 49 (notches) formed in areas facing the side portions 42, 46 of the U-shaped members 28, 30, into which the insulating paper 45 is inserted. The spaces 49 are formed at the connections between the side portions (teeth portions) and middle portions (yoke portions) of the U-shaped members 28, 30. By forming these spaces 49, when the side portions 42, 46 are inserted into the frame holes 25 of the armature coil 24, the ends of the insulating paper 45 are inserted into the spaces 49, as shown in FIG. 12B . This provides appropriate insulation between the U-shaped members 28, 30 and the armature coil 24 by the insulating paper 45.

[0047] [Method of Manufacturing Armature] Next, a method of manufacturing the armature 14 will be described. The holding member 40 is composed of a plurality of blocks, which are assembled together. Each block has the function of bundling and fixing a predetermined number of U-shaped members 28, 30. For example, the plurality of U-shaped members 28 enclosed by the dashed line in FIG. 3 are fixed together as a single block. Also, the U-shaped members 30A to 30C enclosed by the dashed line in FIG. 3 are fixed together as a single block.

[0048] FIG. 13 shows one embodiment of a block 50 that forms the holding member 40, illustrating a fixing structure for multiple U-shaped members 28. FIG. 13A shows a top view of the block 50, and FIG. 13B shows a side view of the block 50. In FIG. 13, the portions of the U-shaped members 28 that are housed within the block 50 are indicated by dashed lines. As shown in FIG. 13, when multiple U-shaped members 28 are bundled together, the middle portions 44 of the U-shaped members 28 are fixed so as to be covered by the block 50. After assembly, multiple U-shaped members 28 that are adjacent in the rotational direction are also fixed by the block 50 in the same manner.

[0049] Each block 50 is formed with an engagement protrusion 52 and an engagement hole 54 that engage with an adjacent block 50 after assembly. The engagement protrusion 52 is located on one side in the rotational direction, while the engagement hole 54 is located on the other side in the rotational direction. During assembly, the engagement protrusions 52 and engagement holes 54 of adjacent blocks 50 are engaged with each other, thereby connecting the adjacent blocks 50. The shapes of the engagement protrusions 52 and the engagement holes 54 are not limited to those shown in FIG. 13 and may be changed as appropriate as long as they are capable of engaging with each other.

[0050] Similarly, the U-shaped members 30A to 30C are fixed in a bundled state by a block. These blocks are formed with engaging protrusions or holes that connect them to adjacent blocks 50 in the axial direction. During assembly, the blocks that fix the U-shaped members 30A to 30C are connected to the blocks 50 by engaging the engaging protrusions or holes with engaging holes or protrusions (not shown) formed in the axial direction of the adjacent blocks 50. This connects adjacent blocks to each other in the rotational and axial directions, forming a holding member 40 that holds the multiple U-shaped members 28, 30 from the radially outer side after the blocks are assembled. In other words, the iron core 26 is formed with the multiple U-shaped members 28, 30 held by the holding member 40.

[0051] Furthermore, instead of the holding member 40 configured by the above-described plurality of blocks, the U-shaped members 28, 30 can be fixed using a holding member 60 formed using a 3D printer.

[0052] Figure 14 is a diagram illustrating a fixing structure for U-shaped members 28 and 30 using a holding member 60. Figure 14A shows an assembly process for inserting U-shaped member 28 into holding member 60, Figure 14B shows the state after U-shaped member 28 has been inserted into holding member 60, and Figure 14C shows the state after U-shaped member 30 has been assembled in addition to U-shaped member 28.

[0053] The holding member 60 has an annular shape and is made of, for example, resin. The holding member 60 has a plurality of insertion holes 62 into which the side portions 42, 46 of the plurality of U-shaped members 28, 30 are respectively inserted. During assembly, the side portions 42, 46 of each U-shaped member 28, 30 are inserted into the corresponding insertion holes 62, and then the U-shaped members 28, 30 are adhered to the holding member 60 using an adhesive or the like. This results in the state shown in Figures 14B and 14C, in which the U-shaped members 28, 30 are fixed to the holding member 60. Note that the holding member 60 may not only be composed of a single member, but may also be composed of a combination of multiple blocks.

[0054] Fig. 15 is a flowchart illustrating the flow of the manufacturing process for the armature 14 made up of the U-shaped members 28, 30. The flowchart in Fig. 15 corresponds to the embodiment using the holding member 40 described above.

[0055] In the first basic step shown in FIG. 15 , wire 32 is bent at predetermined positions and excess portions are cut off to form multiple L-shaped members having desired dimensions. In the second basic step, the L-shaped members formed in the first basic step are joined to form multiple U-shaped members 28, 30 having desired dimensions. In the blocking step, a predetermined number of U-shaped members 28 are bundled and fixed together to form multiple blocks 50, and a predetermined number of U-shaped members 30A-30C are bundled and fixed together to form multiple blocks. In the assembling step, the formed blocks are connected to each other to form a single holding member 40. At this time, adjacent blocks are integrally connected by engaging engaging portions (engaging protrusions 52, engaging holes 54) formed on them. The second basic step corresponds to the "first step" in the present invention, the blocking step corresponds to the "second step" in the present invention, and the assembling step corresponds to the "third step" in the present invention.

[0056] FIG. 16 is a flowchart illustrating the flow of the manufacturing process for the armature 14 when a holding member 60 is used instead of the holding member 40. In the first basic step of FIG. 16 , the wire 32 is bent at predetermined positions and excess portions are cut off to form multiple L-shaped members having desired dimensions. In the second basic step, the L-shaped members formed in the first basic step are joined to form multiple U-shaped members 28, 30 having desired dimensions. In the assembling step, the side portions 42, 46 of the U-shaped members 28, 30 formed in the second basic step are inserted from the radial outside into insertion holes 62 formed in the holding member 60 using a 3D printer, and the U-shaped members 28, 30 are then fixed to the holding member 60 using an adhesive or the like. Note that the second basic step corresponds to the “first step” in this invention, and the assembling step corresponds to the “second step” in this invention.

[0057] [Function, etc.] As described above, by configuring the core 26 with the multiple U-shaped members 28, 30, and by arranging the intermediate portion 44 of the U-shaped member 28 along the direction of rotation and the intermediate portion 48 of the U-shaped member 30 along the rotation axis CL, a magnetic path through which magnetic flux flows three-dimensionally can be easily formed. Furthermore, by fixing the U-shaped members 28, 30 with the holding member 40, the armature 14 (core 26) made up of the multiple U-shaped members 28, 30 can be easily manufactured. Alternatively, the armature 14 (core 26) made up of the multiple U-shaped members 28, 30 can also be easily manufactured by using a holding member 60 having insertion holes 62 into which the side portions 42, 46 of the U-shaped members 28, 30 are inserted.

[0058] [Modifications] While the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and may be modified as appropriate without departing from the spirit and scope of the invention. For example, in the above-described embodiments, the U-shaped members 28, 30 are formed by connecting a pair of L-shaped members 35 to each other. However, if the electric motor 10 is small, for example, the U-shaped members may be formed by bending a single wire 32 at two points.

[0059] In the above embodiment, of the U-shaped members 30A to 30C whose intermediate portions are stacked radially, only the U-shaped member 30C located at the outermost radial position is bent, but the U-shaped members 30A and 30B may also be bent.

[0060] In the above embodiment, two armature coils 24 are arranged in series in the axial direction, but the number is not necessarily limited to two. In other words, three or more armature coils 24 may be arranged in series in the axial direction.

[0061] In the above embodiment, the surfaces of the U-shaped members 28, 30 are coated with an insulating film, but the insulating film may be omitted. For example, the cross-sectional areas of the U-shaped members 28, 30 may be rounded to minimize the contact area between adjacent U-shaped members 28, 30 and reduce loss.

[0062] In the above embodiment, the blocks that secure the multiple U-shaped members 28, 30 have engaging protrusions 52 and engaging holes 54 formed therein, and the adjacent blocks are connected by engaging the engaging protrusions 52 and engaging holes 54 of the adjacent blocks with each other. However, the method of connecting the blocks is not limited to this. For example, screw holes may be formed in each block, and adjacent blocks may be connected by screwing them together. Alternatively, each block may have an engaging portion that engages with a clip, and the adjacent blocks may be connected by a clip that is installed so as to straddle the adjacent blocks. Alternatively, adjacent blocks may be connected by adhesive, welding, or the like.

[0063] In the above embodiment, the U-shaped members 28, 30 are inserted into the insertion holes 62 of the holding member 60 and then fixed by bonding with an adhesive or the like, but the method is not necessarily limited to adhesive. For example, the U-shaped members 28, 30 may be fixed by press-fitting them into the insertion holes 62.

[0064] A first aspect of the present invention relates to an electric motor comprising: an armature having an iron core and an armature coil arranged to surround the iron core; and a mover arranged opposite the armature, wherein the iron core of the armature is composed of a plurality of members made of electromagnetic steel pieces, each of the plurality of members having a U-shape consisting of a pair of side portions that are parallel or approximately parallel to each other and a middle portion connecting the pair of side portions, and the plurality of members including a plurality of first members and a plurality of second members whose middle portions are perpendicular to the longitudinal direction of the middle portions of the first members, and the middle portions of the first members and the middle portions of the second members each constitute yoke portions of the iron core, and the side portions of the first members and the side portions of the second members each constitute teeth portions of the iron core.

[0065] According to the first aspect, by arranging the intermediate portion of the first member and the intermediate portion of the second member, which are formed in a U-shape and constitute the iron core of the armature, so that they face in directions perpendicular to each other, it is possible to easily realize a magnetic path in which magnetic flux flows three-dimensionally.

[0066] In a second aspect of the electric motor, in the electric motor of the first aspect, the mover is configured to be rotatable about a rotation axis, the intermediate portions of the first members are arranged along the rotation direction of the mover, and the intermediate portions of the second members are arranged along the rotation axis. According to this second aspect, it is possible to easily realize a magnetic path in which magnetic flux flows in the rotation direction and the rotation axis direction.

[0067] A third aspect of the electric motor is the electric motor of the second aspect, wherein the plurality of second members are disposed at the center of the armature in the direction of the rotation axis, and the plurality of first members are disposed on both sides of the second members in the direction of the rotation axis of the armature. According to this third aspect, it is possible to form a magnetic path that provides the shortest path for magnetic flux.

[0068] A fourth aspect of the electric motor is the electric motor according to any one of the first to third aspects, wherein the surfaces of the plurality of members made of the electromagnetic steel pieces are each insulated. According to this third aspect, it is possible to effectively reduce losses due to the generation of eddy currents.

[0069] According to a fifth aspect, in the electric motor of any one of the first to fourth aspects, the electromagnetic steel billets are made of wire rods. According to this fifth aspect, a U-shaped member can be easily formed by bending the wire rods.

[0070] According to a sixth aspect, in the electric motor of any one of the first to fifth aspects, each of the plurality of second members is arranged such that the pair of side portions overlap the pair of side portions of the adjacent second member in the direction of the rotation axis and the intermediate portion overlaps the intermediate portion of the adjacent second member in the radial direction about the rotation axis, and the second members having the pair of side portions located at both ends in the direction of the rotation axis have at least the intermediate portion bent in the rotation direction relative to the pair of side portions. According to this sixth aspect, since the intermediate portions of the second members are arranged to overlap in the radial direction, the iron core is likely to become large in size in the radial direction, whereas the second members having at least one pair of side portions located at both ends in the direction of the rotation axis have the intermediate portion bent in the rotation direction relative to the pair of side portions, thereby reducing the radial size of the iron core.

[0071] A seventh aspect of the electric motor is the electric motor according to any one of the first to sixth aspects, further comprising a retaining member made of resin that holds the entire yoke portion formed by the intermediate portions of the plurality of members from the radially outer side. According to this seventh aspect, deformation of the iron core during operation of the electric motor can be suppressed by the retaining member. Furthermore, since the retaining member is made of resin, weight increase due to the provision of the retaining member can be reduced.

[0072] An electric motor according to an eighth aspect is the electric motor according to the seventh aspect, wherein the holding member has insertion holes into which the side portions of the plurality of members are respectively inserted from the radially outer side. According to this eighth aspect, during assembly, the iron core can be easily constructed by respectively inserting the side portions of the plurality of members into the insertion holes formed in the holding member.

[0073] According to a ninth aspect of the present invention, a method of manufacturing an armature for manufacturing the electric motor of the seventh aspect includes a first step of molding each of the plurality of first members and the plurality of second members, a second step of molding a plurality of blocks in which a predetermined number of the plurality of first members and the plurality of second members are fixed, and a third step of connecting the plurality of blocks to form the holding member. According to this ninth aspect, by molding a plurality of blocks in which a predetermined number of first members and second members are fixed and connecting the plurality of blocks to form the holding member, it is possible to easily manufacture an armature made of a plurality of first members and a plurality of second members.

[0074] According to a tenth aspect of the present invention, a method of manufacturing an armature for manufacturing the electric motor of the eighth aspect includes a first step of shaping the plurality of first members and the plurality of second members, and a second step of inserting the side portions of each of the plurality of first members and the side portions of each of the plurality of second members into the insertion holes formed in the holding member. According to this tenth aspect, by inserting the side portions of each of the plurality of first members and the side portions of each of the plurality of second members into the insertion holes formed in the holding member, an armature made of the plurality of first members and the plurality of second members can be easily manufactured.

Claims

1. An electric motor comprising: an armature having an iron core and an armature coil arranged to surround the iron core; and a mover arranged opposite the armature, wherein the iron core of the armature is composed of a plurality of members made of electromagnetic steel pieces, each of the plurality of members has a U-shape consisting of a pair of side portions that are parallel or approximately parallel to each other and a middle portion connecting the pair of side portions, the plurality of members including a plurality of first members and a plurality of second members, the longitudinal direction of the middle portions being perpendicular to the longitudinal direction of the middle portions of the first members, the middle portions of the first members and the middle portions of the second members each constitute a yoke portion of the iron core, and the side portions of the first member and the side portions of the second member each constitute teeth portions of the iron core.

2. An electric motor as described in claim 1, characterized in that the mover is configured to be rotatable around a rotation axis, the plurality of first members have their intermediate portions arranged along the rotation direction of the mover, and the plurality of second members have their intermediate portions arranged along the rotation axis.

3. The electric motor according to claim 2, characterized in that the plurality of second members are arranged at the center of the armature in the direction of the rotation axis, and the plurality of first members are arranged on both sides of the second member in the direction of the rotation axis of the armature.

4. The electric motor according to any one of claims 1 to 3, wherein the surfaces of the plurality of members made of the electromagnetic steel pieces are each coated with an insulating material.

5. The electric motor according to any one of claims 1 to 3, wherein the electromagnetic steel pieces are made of wire.

6. An electric motor as claimed in any one of claims 2 or 3, characterized in that each of the multiple second members is arranged such that the pair of side portions overlap with the pair of side portions of the adjacent second member in the direction of the rotation axis and the intermediate portion overlaps with the intermediate portion of the adjacent second member in the radial direction centered on the rotation axis, and that the second member having the pair of side portions located at both ends in the direction of the rotation axis has at least the intermediate portion bent in the rotational direction relative to the pair of side portions.

7. An electric motor as claimed in any one of claims 1 to 3, further comprising a retaining member made of resin for retaining the entire yoke portion formed by the intermediate portions of the plurality of members from the radially outer side.

8. The electric motor according to claim 7, wherein said holding member has insertion holes into which said side portions of said plurality of members are respectively inserted from the radially outer side.

9. A method for manufacturing the armature constituting the electric motor described in claim 7, comprising: a first step of forming each of the plurality of first members and the plurality of second members; a second step of forming a plurality of blocks in which the plurality of first members and the plurality of second members are fixed in predetermined numbers; and a third step of connecting the plurality of blocks to each other to form the holding member.

10. A method for manufacturing an armature constituting the electric motor described in claim 8, comprising: a first step of molding each of the plurality of first members and each of the plurality of second members; and a second step of inserting each of the side portions of the plurality of first members and each of the side portions of the plurality of second members into the insertion holes of the holding member.

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