JP6654551B2 - Electric motor - Google Patents

Description

  The present invention relates to a motor having a field element and an armature, and more particularly, to a shape of a motor tooth around which a coil is wound.

  The electric motor includes a field element having a permanent magnet and an armature having a coil forming an electromagnet. In a rotary motor, a field element and an armature are arranged concentrically. For example, in a rotary motor such as a brushless type synchronous motor, a field element becomes a rotor, and an armature becomes a stator. In the case of the inner rotor type, generally, the iron core of the armature includes a cylindrical back yoke and a plurality of teeth protruding radially inward from the back yoke and arranged in a circumferential direction of the back yoke. An exciting coil is wound around each of these teeth.

  On the other hand, in a linear motor (linear motor), a plurality of armatures (coils) are linearly arranged as stators, and a field element as a mover moves on a linearly arranged coil. Among the linear motors, there is a cylindrical motor in which a field element and an armature are concentrically arranged for high thrust (for example, see Patent Document 1). In a cylindrical linear motor, a plurality of armature cores similar to the above-described inner rotor type rotary motor are arranged in the moving axis direction of the mover.

JP 2014-504129 A

  In designing an electric motor, it is important to secure a space for arranging coils. If a large arrangement space can be ensured, a conductor having a large cross-sectional area can be selected as a coil conductor, whereby a Joule loss can be reduced and a large current can flow. Further, the number of turns of the coil can be increased, and the amount of magnetic flux generated by the coil can be increased to improve the motor output. However, generally, an increase in the coil arrangement space leads to an increase in the size of the electric motor. Therefore, when there is a demand for a reduction in the size of the electric motor, it is difficult to secure a wide coil arrangement space.

  In order to obtain a higher thrust in a linear motor, it is effective to increase the number of armatures arranged per unit length. However, when the armature cores are densely arranged, the space for arranging the coils is naturally reduced, so that there is a limit in improving the thrust. It is conceivable to reduce the thickness of the armature core (teeth), but in this case, magnetic saturation occurs, which causes a reduction in thrust and an increase in loss. That is, it is difficult to secure a wide coil arrangement space while securing an appropriate tooth size.

  An object of the present invention is to provide an electric motor having an armature tooth shape capable of securing as large a coil arrangement space as possible without increasing the size of the electric motor.

An electric motor according to one aspect of the present invention includes a field element having a permanent magnet, a cylindrical back yoke, and a plurality of projections projecting radially inward from the back yoke and arranged in a circumferential direction of the back yoke. An armature including a tooth and a plurality of coils wound around each of the teeth, the tooth including a root portion near the back yoke and a tip portion near a protruding end portion, The cross-sectional area of the root portion and the cross-sectional area of the tip portion are substantially the same, while the root portion increases the inner diameter of the coil along the circumferential direction of the back yoke as compared with the tip portion. An electric motor having a shape that reduces the inner diameter of the coil along the axial direction of the back yoke , wherein the teeth have a circumferential width along a circumferential direction of the back yoke and an axial direction of the back yoke. Along An axial width, wherein the circumferential width is such that the root portion is wider than the tip portion, and the axial width is that the root portion is narrower than the tip portion. Further comprising a non-winding tooth disposed between the plurality of teeth arranged in the circumferential direction, wherein the coil is not wound, wherein the circumferential width of the non-winding tooth is such that the root portion is larger than the tip portion. The width of the non-wound teeth in the axial direction is narrower at the root portion than at the distal end portion .

  In a core structure in which teeth protrude radially inward from a cylindrical back yoke, it is assumed that the cross-sectional shape of the teeth is constant in the radial direction. In this case, the space between the adjacent teeth, that is, the coil arrangement space, is larger between the root portions than between the tip portions of the teeth. Therefore, a dead space that is not occupied by the coil is likely to occur between the root portions. When the coil is wound so as to fill the dead space, the coil end (the outer peripheral surface of the coil) swells between the roots, occupying extra space in the axial direction. Further, in a linear motor in which the armature cores are densely arranged in the moving axis direction, a form in which the coil swells in the axial direction cannot be adopted.

  However, according to the above-described electric motor, since the cross-sectional area of the root portion of the tooth and the cross-sectional area of the tip portion are substantially the same, it is possible to secure a cross-sectional area that does not cause magnetic saturation over the entire length of the tooth. Becomes The root portion has a shape in which the inner diameter of the coil increases in the circumferential direction of the back yoke and decreases in the axial direction as compared with the tip portion. The provision of such a tooth having an adjustable coil inner diameter can reduce the dead space generated between the root portions of adjacent teeth. Further, it is possible to prevent the coil end from protruding in the axial direction at the root portion.

Further , the teeth have a circumferential width along a circumferential direction of the back yoke and an axial width along an axial direction of the back yoke, and the circumferential width is such that the root portion is the tip portion. is wider than the axial width, said root portion that is narrower than the tip portion. Further, the coil further includes a non-winding tooth that is arranged between a plurality of teeth arranged in the circumferential direction and the coil is not wound, and the circumferential width of the non-winding tooth is such that the root portion is larger than the tip portion. The axial width of the unwound tooth is wider at the root portion than at the distal end portion.

According to this electric motor, by setting the circumferential width and the axial width of the teeth as described above, the inner diameter of the coil at the root portion naturally increases in the circumferential direction of the back yoke and decreases in the axial direction. be able to. Further, in some types of armatures, not all the teeth are wound with coils, but non-wound teeth in which the coils are not wound are arranged between normal teeth. Accordingly, there is an advantage that the space required for insulation between the coils can be reduced and the number of winding steps of the coils can be reduced. In the case where such a tooth structure is employed, the circumferential width and the axial width of the non-winding teeth are set as described above, thereby increasing the coil arrangement space between the normal teeth and the non-winding teeth. be able to.

  In this case, it is more preferable that the circumferential width is wider as approaching the back yoke, and that the axial width is narrower as approaching the back yoke.

  According to this electric motor, by increasing the circumferential width toward the back yoke, the space between the teeth that expands toward the base portion can be effectively used as a coil arrangement space. Further, by making the axial width narrower as approaching the back yoke, the coil end can be easily flattened.

  In the above electric motor, the back yoke forms the cylindrical shape by combining a plurality of circumferential division pieces, and each of the circumferential division pieces integrally includes a part of the teeth, and Each of the divided pieces is composed of a combination of a first piece, a second piece, and a third piece further divided in the axial direction, and the third piece is disposed between the first piece and the second piece. The first piece and the second piece each have a shape in which the axial width is smaller at the root portion than the tip portion, and the third piece is such that the axial width is smaller than the root width. It is desirable to have a shape that is constant from part to the tip.

  According to this electric motor, in the operation of assembling the coil to the teeth, the coil is inserted into the intermediate assembly in which the first piece and the second piece having irregular shapes at the root portion and the tip portion are adjacent to each other, Thereafter, an operation of cutting the third piece into the intermediate assembly becomes possible. Therefore, even if the coil has a smaller inner diameter at the base near the back yoke, the coil can be easily assembled to the teeth.

  In the above-mentioned electric motor, it is preferable that the electric motor is a linear motor in which a plurality of the armatures as a stator are arranged in a movable axis direction of the field element as a mover.

  According to this electric motor, a wide coil arrangement space can be secured while securing an appropriate tooth cross-sectional area, so that the number of armatures arranged per unit length can be increased. Therefore, it is possible to provide a linear motor that generates a high thrust.

  In the above electric motor, it is preferable that the electric motor is a rotary electric motor.

  According to this motor, even when the winding amount of the coil is increased at the root portion, the coil end can be formed so as not to bulge at the root portion. Can be provided.

  ADVANTAGE OF THE INVENTION According to the electric motor which concerns on this invention, the electric motor provided with the armature tooth shape which can secure a large coil arrangement space can be provided, without enlarging an electric motor.

FIG. 1 is a cross-sectional view showing an example of a general brushless type rotary electric motor. FIG. 2 is a diagram schematically illustrating an example of a linear motor. FIG. 3A is an enlarged view of a main part of FIG. 4A is an enlarged view of a main part when a coil is wound so as to fill a dead space, and FIG. 4B is a diagram schematically illustrating an axial cross section of FIG. 4A. . FIG. 5 is a perspective view showing an armature core of the electric motor according to the embodiment of the present invention. FIG. 6 is a perspective view showing the armature according to the embodiment of the present invention, and is a perspective view showing a state in which a coil is wound around the teeth of the armature core of FIG. FIG. 7A is a plan view of the teeth of the armature core shown in FIG. 5 as viewed in the axial direction, and FIG. 7B is a side view of the teeth. FIG. 8A is a plan view of the state in which a coil is wound around the teeth as viewed in the axial direction, and FIG. 8B is a side view thereof. 9A is a view schematically showing an axial section of the electric motor according to the embodiment, FIG. 9B is a sectional view taken along line IXB-IXB of FIG. 9A, and FIG. It is IXC-IXC sectional view taken on the line of FIG. 9 (A). FIG. 10 is a diagram showing one of the core pieces constituting the armature core. FIG. 11 is an exploded perspective view of the core piece when the core piece is composed of a plurality of divided pieces. FIGS. 12A to 12C are views showing a procedure for assembling a coil to the iron core piece. FIG. 13 is a perspective view showing an armature core of an electric motor according to a modified embodiment. FIG. 14 is a perspective view illustrating an armature according to a modified embodiment, and is a plan view illustrating a state where a coil is wound around teeth of the armature core of FIG. 13.

[Example of motor to which the present invention can be applied]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, an example of a motor to which the present invention can be applied will be described. FIG. 1 is a cross-sectional view illustrating an example of a general brushless type rotary electric motor 100. The rotary motor 100 includes a field element 110 and an armature 120 arranged concentrically. The field element 110 is a rotor, the armature 120 is a stator, and the field element 110 is rotatably housed inside the cylindrical armature 120.

  The field element 110 includes a shaft 111 extending in the output axis direction (z direction) of the rotary motor 100, and a cylindrical rotor core 112 attached to the shaft 111. Near the outer peripheral portion of the rotor core 112, a plurality of permanent magnets 113 are arranged in the circumferential direction (θ direction). The plurality of permanent magnets 113 form a magnetic pole on the outer peripheral portion of the rotor core 112, and are arranged so that the polarities are alternately different in the θ direction.

  The armature 120 includes an armature core 121 and a coil 124. The armature core 121 includes a cylindrical back yoke 122 and a plurality of teeth 123 around which a coil 124 is wound. The plurality of teeth 123 project from the inner peripheral wall of the back yoke 122 inward in the radial direction (r direction), and are arranged at a constant pitch in the circumferential direction of the back yoke 122. The insulated conductor forming the coil 124 has each tooth 123 as a core, and is wound around the outer periphery of the tooth 123 in a direction orthogonal to the r direction. When an exciting current is applied to each coil 124, a rotating magnetic field is formed, and the permanent magnet 113 is attracted, so that the field element 110 rotates around the shaft 111.

  The armature core 121 is generally formed of a laminate of a plurality of electromagnetic steel sheets. Such a laminated core is advantageous in terms of suppressing eddy current. In addition, the armature core 121 may be a dust core. The dust core is a core formed by strongly pressing magnetic iron powder having isotropic magnetic properties. The dust core is advantageous in that the airtightness is higher than that of the laminated core and the degree of freedom in molding is higher. Also, in the flow of the magnetic flux, only a two-dimensional flow of the magnetic flux can be formed in the laminated core because of the presence of the voids in the laminated portion. It is possible to form a flow of magnetic flux.

  FIG. 2 is a diagram schematically illustrating an example of a linear motion motor (linear motor) 200. Here, a linear motion motor 200 driven by three-phase AC is shown. The linear motor 200 includes a field element 210 as a mover that moves along a preset linear movable axis (z direction) and an armature 220 as a stator. The field element 210 includes a shaft 211 extending in the z direction, and a mover core 212 attached to the shaft 211. A plurality of permanent magnets 213 are attached to the mover core 212. The plurality of permanent magnets 213 are arranged so that the polarities are alternately different in the z direction.

  The armature 220 has at least three armature units 220U, 220V, 220W arranged in the z direction. Each of the armature units 220U, 220V, and 220W has the same configuration as the above-described armature 120, and includes an armature core 221 having a back yoke 222 and teeth 223, and a coil 224 wound around the teeth 223. When a three-phase AC exciting current is applied to each coil 224, a thrust that travels in the z direction is given to the field element 210.

  FIG. 3 is an enlarged view of the teeth 123 shown in FIG. The teeth 123 include a root portion 123 </ b> A near a rising portion from the back yoke 122, a tip portion 123 </ b> B near a protruding end portion of the teeth 123, and a tip flange portion 123 </ b> C for preventing the coil 124 from coming off. The conventional general tooth 123 has a rectangular cross section, and has the same shape from the root part 123A to the tip part 123B. That is, the teeth 123 have the same width in the θ direction (width in the circumferential direction) and the width in the z direction (width in the axial direction) over the entire length in the r direction (radial direction) except for the distal end flange portion 123C. The coil 124 is wound from the root portion 123A to the tip portion 123B.

  The plurality of teeth 123 are arranged radially in the r direction from the z axis. The gap between the adjacent teeth 123 becomes a coil arrangement space (slot) for accommodating the coil 124. In the case of the teeth 123 having the same cross-sectional shape in the r direction, the interval between the adjacent teeth 123 in the θ direction is wider at the root portion 123A than at the tip portion 123B. For this reason, when the winding thickness of the coil 124 is constant in the r direction, the dead space DS not occupied by the coil 124 is formed relatively wide in the adjacent root portion 123A.

  FIG. 4A is an enlarged view of a main part when the coil 124 is wound so as to fill the dead space DS shown in FIG. The coil 124 includes an additional coil unit 124E using the dead space DS. The additional coil portion 124E is formed by increasing the number of coil turns toward the outside of the teeth 123 in the r direction. Note that, in the figure, the additional coil portion 124E is shown to facilitate identification of the portion increased compared to FIG. 3, but the actual additional coil portion 124E is wound around one insulated wire. It is a part of the coil 124 formed by turns.

  FIG. 4B is a diagram schematically showing an axial cross section of FIG. 4A. Assuming that the coil 124 is wound so as to include the additional coil portion 124E so as to fill the dead space DS, the coil end 125, which is the outer peripheral surface of the coil 124 facing the z direction, has a shape bulging at the root portion 123A. . Therefore, the coil 124 occupies extra space in the z direction.

  This means that in the case of the rotary electric motor 100 shown in FIG. 1, the length in the z-direction increases, so that miniaturization of the rotary electric motor 100 is hindered. On the other hand, in the case of the linear motor 200 shown in FIG. 2, between the armature units 220U, 220V, and 220W, the coil ends 125 are adjacent to each other in the z direction (movable axis direction). In this case, since the armature iron cores 221 need to be densely arranged in the z direction, the coil 124 in a winding mode in which the additional coil portion 124E protrudes in the z direction cannot be adopted.

[The armature according to the embodiment of the present invention]
In view of the above problems, the present embodiment exemplifies an electric motor having a tooth shape capable of securing a wide coil arrangement space without increasing the size of the electric motor and securing an appropriate tooth size. FIG. 5 is a perspective view showing the armature core 21 of the electric motor according to the embodiment of the present invention. FIG. 6 is a perspective view showing a state in which coil 24 is wound around teeth 23 of armature core 21 in FIG. The electric motor here may be either the rotary electric motor 100 shown in FIG. 1 or the linear motor 200 shown in FIG. Accordingly, the armature core 21 is a member corresponding to the armature core 121 of the rotary motor 100 or the armature core 221 of the linear motor 200. In addition, the rotary electric motor 100 includes both a motor and a generator.

  The armature core 21 includes a back yoke 22 and a plurality of teeth 23 around which the coil 24 is wound. The armature core 21 is formed of a dust core formed by compacting and molding magnetic iron powder. The back yoke 22 is a cylindrical member having an annular inner peripheral wall 22A and an outer peripheral wall 22B. The plurality of teeth 23 project from the inner peripheral wall 22 </ b> A of the back yoke 22 inward in the radial direction (r direction), and are arranged at a constant pitch in the circumferential direction of the back yoke 22 (θ direction). FIG. 5 shows an example in which eight teeth 23 are arranged at equal pitches in the θ direction.

  The width of the back yoke 22 in the r direction is constant in the θ direction. The thickness of the back yoke 22 in the axial direction (z direction) is greater than the thickness of the teeth 23 in the z direction, and the teeth 23 project from the vicinity of the center of the back yoke 22 in the z direction to the inside in the r direction. Further, the back yoke 22 includes a lead wire lead-out portion 22C corresponding to the arrangement position of each tooth 23. The lead wire lead-out portion 22C is a concave portion in which a part of the back yoke 22 is cut out, and is a portion from which the coil start or end of the insulated conductor forming the coil 24 is pulled out.

  The teeth 23 include a root portion 23A near a rising portion inward in the r direction from the back yoke 22, a tip portion 23B near a protruding end portion of the teeth 23, and a top portion 23C that is the protruding end portion. A substantially cylindrical space exists inside the top 23C. The field element 10 is inserted into this space (see FIG. 9A). That is, the top 23 </ b> C faces the outer peripheral surface of the rotor core 12 of the field element 10.

  FIG. 6 shows an armature 20 of the present embodiment. The armature 20 includes the above-described armature core 21 and a plurality of coils 24. The plurality of coils 24 are wound around eight teeth 23, respectively. The insulated conductor forming the coil 24 has each tooth 23 as a core and is wound around the outer periphery of the tooth 23 in a direction perpendicular to the r direction. The coil 24 is wound between the root portion 23A and the tip portion 23B, and the top portion 23C protrudes from the inner end surface of the coil 24 in the r direction. When an exciting current is applied to each coil 24, a rotating magnetic field is formed, and the permanent magnet 13 provided in the rotor core 12 is attracted, so that the field element 10 rotates around the shaft 11.

[Details of tooth shape]
The shape of the teeth 23 will be described in detail. FIG. 7A is a plan view of the teeth 23 as viewed in the z direction, and FIG. 7B is a side view of the teeth 23. The teeth 23 of the present embodiment have a rectangular cross section in the θ direction, but have different cross sectional shapes in the r direction, that is, different cross sectional shapes at the root portion 23A and the distal end portion 23B. The root portion 23A of the tooth 23 has a circumferential width θ1 along the θ direction and an axial width z1 along the z direction. Similarly, the tip portion 23B has a circumferential width θ2 along the θ direction and an axial width z2 along the z direction.

  Regarding the circumferential width, the root portion 23A is wider than the distal end portion 23B, while the axial width is such that the root portion 23A is narrower than the distal end portion 23B. That is, the teeth 23 have a shape in which θ1> θ2 as shown in FIG. 7A, and a shape in which z1 <z2 as shown in FIG. 7B. The width of the teeth 23 in the θ direction is increased as approaching the back yoke 22, and the width in the z direction is decreased as approaching the back yoke 22.

  By adopting such a shape, the side surface 231 (the surface extending in the z direction) of the tooth 23 has a slope along the r direction more than that of a conventional tooth whose cross-sectional shape is constant in the r direction. . Therefore, a large difference does not occur between the root portion 23A and the distal end portion 23B in the width in the θ direction of the gap (slot) between the side surfaces 231 of the adjacent teeth 23. In the present embodiment, the width of the gap at the root portion 23A is slightly wider than the tip portion 23B. This contributes to reducing the dead space DS (see FIG. 3) generated between the adjacent root portions 23A and not occupied by the coil 24. The pair of end surfaces 232 (surfaces extending in the r direction) of the teeth 23 are tapered surfaces that gradually become narrower from the distal end portion 23B toward the root portion 23A. Therefore, in the z section, the coil arrangement space in the root portion 23A is expanded.

  FIG. 8A is a plan view of the state in which the coil 24 is wound around the teeth 23 when viewed in the axial direction, and FIG. 8B is a side view thereof. 8A and 8B, the coil 24 is drawn in a cross section. Further, a state is shown in which a coil end conductor 241 serving as a starting end or a terminating end of the coil 24 is pulled out from a lead wire drawing portion 22 </ b> C of the back yoke 22. As shown in FIG. 8A, a large dead space is formed between the root portions 23A of the adjacent teeth 23 by winding the coil 24 around each of the teeth 23 having the above-mentioned shape characteristic of θ1> θ2. Has not occurred. Further, as shown in FIG. 8B, the coil end 242 which is the end surface in the z direction of the coil 24 is flat by having the above-mentioned z1 <z2.

  9A is a view schematically showing an axial section of the rotary electric motor 1 according to the present embodiment, FIG. 9B is a sectional view taken along line IXB-IXB of FIG. 9A, and FIG. 9) is a sectional view taken along line IXC-IXC of FIG. The rotary motor 1 includes the field element 10 and the above-described armature 20 that are arranged concentrically. The field element 10 includes a shaft 11 extending in the z direction, and a cylindrical rotor core 12 attached to the shaft 11. Near the outer peripheral portion of the rotor core 12, a plurality of permanent magnets 13 are arranged in the circumferential direction. The armature 20 includes the armature core 21 and the coil 24 as described above, and the top 23C of the teeth 23 and the outer peripheral surface of the rotor core 12 in which the permanent magnets 13 are embedded oppose each other with a predetermined gap in the r direction. Are arranged as follows.

As shown in FIGS. 9B and 9C, in the cross-sectional shape of the teeth 23, the root portion 23A has the circumferential width θ1 and the axial width z1, and the tip portion 23B has the circumferential width θ2 (θ1> θ2) and the shaft. Each has a direction width z2 (z1 <z2), and both have different shapes. However, the cross-sectional area of the root portion 23A and the cross-sectional area of the tip portion 23B are substantially the same. That is,
Sectional area A1 of root portion 23A = θ1 × z1
Cross-sectional area A2 of tip portion 23B = θ2 × z2
A1 ≒ A2
The relationship has been. The cross-sectional areas A1 and A2 are selected such that magnetic saturation does not occur when the coil 24 is energized. The cross-sectional areas A1 and A2 are substantially the same when both are completely the same, when there is an area difference based on an unavoidable tolerance, or when substantially the same from the viewpoint of magnetic saturation characteristics. This is a concept including a case where there is an area difference within a range that can be considered as.

  The inner diameter of the coil 24 depends on the circumferential widths θ1, θ2 and the axial widths z1, z2. That is, at the root portion 23A of the tooth 23, the coil 24 has an inner diameter of θ1 in the circumferential direction and z1 in the axial direction. In the tip portion 23B, the coil 24 has an inner diameter of θ2 in the circumferential direction and z2 in the axial direction. That is, the teeth 23 have a shape in which the root portion 23A increases the inner diameter of the coil 24 along the θ direction of the back yoke 22 and decreases the inner diameter of the coil 24 along the z direction, as compared with the tip portion 23B. are doing.

  The coil 24 is wound thicker at the root portion 23A than at the tip portion 23B. That is, the number of coil turns is set so that the coil winding thickness t1 on the teeth 23 at the root portion 23A is larger than the coil winding thickness t2 on the teeth 23 at the tip portion 23B (t1> t2). This is because the root portion 23A is located on the outer side in the r direction than the tip portion 23B, and the root portion 23A can take more coil arrangement space if A1ＡA2 described above.

  However, even if the coil winding thickness is in a relationship of t1> t2, the thickness between the pair of coil ends 242 facing each other in the z direction is the thickness tA of the root portion 23A and the thickness tB of the tip portion 23B. Are substantially the same (tA ≒ tB). That is, the coil end 242 is a flat surface extending in the r direction, and is substantially flush with the end surface in the z direction of the back yoke 22 serving as a flange portion, as in the comparative example shown in FIG. The coil end 242 does not bulge significantly in the z direction. That is, in the present embodiment, although the number of coil turns increases from the distal end portion 23B toward the root portion 23A, the increase is absorbed by the shape of the teeth 23 and does not appear on the coil end 242. This is because, as schematically shown in FIG. 9A, the additional coil portion 24E generated by the increase in the number of coil turns is accommodated in the space in the z direction created by the tapered tapered shape of the end surface 232 of the teeth 23. This is because that.

[Example of armature manufacturing method]
It is difficult to manufacture the armature core 21 as shown in FIG. 5 as an integrally molded product. A preferred manufacturing method is a method in which the back yoke 22 is divided into a plurality of circumferentially divided pieces (circular pieces) and formed into a cylindrical shape by combining these divided pieces. Further, it is preferable that a part of the teeth 23 is formed integrally with the circumferential division piece to form an armature piece in which the armature core 21 itself is divided in the circumferential direction. The armature core 21 can be manufactured by manufacturing a required number of such core pieces and assembling them into a cylindrical shape.

  FIG. 10 is a diagram illustrating an example of one core piece 30 (circumferentially divided piece) constituting the armature core 21. Iron core piece 30 includes a back yoke portion 31 and two teeth portions 32. The back yoke portion 31 is formed by an arc piece having a length obtained by dividing the back yoke 22 of the armature core 21 shown in FIG. The two teeth portions 32 each have a shape in which one tooth 23 is divided into two in the circumferential direction. The teeth 32 are formed integrally with the back yoke 31. Such an iron core piece 30 is desirably formed of the above-mentioned dust core.

  In manufacturing the armature core 21, eight core pieces 30 shown in FIG. 10 are prepared. These are arranged in an annular shape such that the back yoke portions 31 and the teeth portions 32 of the adjacent iron core pieces 30 are in contact with each other. The armature core 21 is assembled by fixing the annular array body to a support plate (not shown) provided in the rotary motor 1.

  In order to manufacture the armature 20, it is necessary to wind the coil 24 around the teeth 23 of the armature core 21. Here, by adopting a manufacturing method in which the coil 24 is wound in advance and fitted into the teeth 23, the manufacturing efficiency can be increased. In this case, the coil 24 is fitted from the top 23 </ b> C side of the teeth 23. However, in the teeth 23 of the present embodiment, the root portion 23A and the distal end portion 23B have irregular shapes, and the distal end portion 23B is wider than the root portion 23A in the z-direction size. The coil 24 has a form in which the additional coil portion 24E protrudes inward (see FIG. 9A). Therefore, the coil 24 cannot be fitted into the teeth 23. This problem can be solved by further configuring the core piece 30 with a plurality of divided pieces.

  FIG. 11 is an exploded perspective view of the iron core piece 30 shown in FIG. 10 when the iron core piece 30 is further composed of a plurality of divided pieces in the z direction. Each of the core pieces 30 is composed of a combination of a first piece 41, a second piece 42, and a third piece 43 divided in the z direction. A third piece 43 is arranged between the first piece 41 and the second piece 42. Here, according to the state shown in FIG. 11, the first piece 41 is treated as the upper side, the second piece 42 is regarded as the lower side, and the third piece 43 is regarded as the center.

  The first piece 41 includes a back yoke piece 411 that forms substantially the upper third of the back yoke section 31 of the iron core piece 30 and a pair of tooth pieces 412 that form a substantially upper third of the pair of tooth sections 32. And The width of the tooth piece 412 in the z direction is smaller at the root portion 412A than at the tip portion 412B. For this reason, the upper surface 413 of the tooth piece 412 is an inclined surface that is inclined downward toward the outside in the r direction. On the other hand, the lower surface 414 of the tooth piece 412 is a plane extending in the r direction without inclination. The width of the tooth piece 412 in the θ direction is wider at the root portion 412A than at the tip portion 412B. These reflect the shape of the teeth 23.

  The second piece 42 includes a back yoke piece 421 that forms approximately one-third lower side of the back yoke part 31 and a pair of teeth pieces 422 that make up approximately one-third lower side of the pair of tooth parts 32. Prepare. The width of the tooth piece 422 in the z direction is smaller at the root portion 422A than at the tip portion 422B. The lower surface 423 of the tooth piece 422 is an inclined surface that is inclined upward toward the outside in the r direction. On the other hand, the upper surface 424 of the tooth piece 422 is a plane extending in the r direction without inclination. The width of the tooth piece 422 in the θ direction is wider at the root portion 422A than at the tip portion 422B.

  The third piece 43 includes a back yoke piece 431 that forms approximately one third of the center of the back yoke part 31 and a pair of tooth pieces 432 that make up approximately one third of the center of the pair of tooth parts 32. The width of the tooth piece 432 in the z direction is constant from the root portion 432A to the tip portion 432B. Therefore, both the upper surface 433 and the lower surface 434 of the tooth piece 432 are planes extending in the r direction that are inclined, and both are parallel. On the other hand, the width of the tooth piece 432 in the θ direction is wider at the root portion 432A than at the tip portion 432B.

  FIGS. 12 (A) to 12 (C) are diagrams showing an operation procedure for assembling the coil 24 wound in advance on the iron core piece 30. As the coil 24, a coil having an additional coil portion 24E inside the coil is prepared in advance. As shown in FIG. 12A, first, an intermediate assembly of the first piece 41 and the second piece 42 of the iron core piece 30 is inserted into the coil 24 from the side of the tip portions 412B and 422B. At this time, the lower surface 414 of the first piece 41 and the upper surface 424 of the second piece 42 are in a state where they abut each other. In this state, the z-direction width of the distal end portions 412B and 422B of the intermediate assembly is smaller than the root inner diameter portion 24A of the coil 24, because the third piece 43 is hollowed out. Therefore, the tip portions 412B and 422B can be inserted into the coil 24. After insertion, the root inner diameter portion 24A of the coil 24 faces the root portions 412A and 422A of the first piece 41 and the second piece 42, and the distal inner diameter portion 24B faces the distal end portions 412B and 422B.

  Subsequently, as shown in FIG. 12B, the space between the first piece 41 and the second piece 42 inserted into the coil 24 is vertically expanded. Thus, a space G is formed between the lower surface 414 of the first piece 41 and the upper surface 424 of the second piece 42. The lower surface 414 and the upper surface 424 that define the space G are wall surfaces parallel to the r direction, and the width of the space in the z direction is substantially the same as the width of the third piece 43 in the z direction. The third piece 43 is inserted into the space G. Since the width of the third piece 43 tooth piece 432 in the z direction is constant, the third piece 43 can be easily inserted into the space G.

  As a result, as shown in FIG. 12C, the first piece 41, the third piece 43, and the second piece 42 are arranged in order from the top, and the final shape of the core piece 30 is formed. At this time, the upper surface 433 of the tooth piece 432 abuts on the lower surface 414 of the first piece 41, and the lower surface 434 abuts on the upper surface 424 of the second piece 42. Further, the coil 24 is in a state of being fitted into the iron core piece 30.

  According to the above-described manufacturing method, in the operation of assembling the coil 24 to the teeth 23, the coil 24 is attached to the intermediate assembly in which the first piece 41 and the second piece 42 having different shapes at the root portion and the tip portion are adjacent to each other. And then the third piece 43 is cut into the intermediate assembly. Therefore, even if the coil 24 has a smaller inner diameter on the side of the root portion 23A, the coil 24 can be easily assembled to the teeth 23.

[Effects]
According to the electric motor according to the present embodiment described above, the cross-sectional area A1 of the root portion 23A of the teeth 23 and the cross-sectional area A2 of the distal end portion 23B are substantially the same. By setting the cross-sectional areas A1 and A2 to a value that does not cause magnetic saturation when the coil 24 is energized, an appropriate cross-sectional area can be secured over the entire length of the teeth 23 in the r direction. The root portion 23A has a shape that increases the inner diameter of the coil 24 in the θ direction and decreases in the z direction as compared with the tip portion 23B. By providing the teeth 23 that can set the inner diameter of the coil, the dead space DS generated between the root portions 23A of the adjacent teeth 23 can be reduced. Further, it is possible to prevent the coil end 242 from protruding in the z direction at the root portion 23A.

  Specifically, in the cross-sectional shape of the teeth 23, the root portion 23A has a circumferential width θ1 and an axial width z1, the tip portion 23B has a circumferential width θ2 and an axial width z2, respectively. θ1> θ2, and the axial width is z1 <z2. By setting the circumferential width and the axial width of the teeth 23 in this manner, the inner diameter of the coil 24 at the root portion 23A can be naturally increased in the θ direction and decreased in the z direction.

  Further, the width in the θ direction is wider as approaching the back yoke 22, and the width in the z direction is narrower as approaching the back yoke 22. Thereby, the space between the teeth 23 that expands toward the root portion 23A can be effectively used as a coil arrangement space. In addition, since the width in the z direction is gradually reduced, the coil end 242 can be easily flattened.

  When the electric motor to which the present invention is applied is the rotary electric motors 100 and 1 as shown in FIGS. 1 and 9A, there is an advantage that the size in the z direction can be reduced. That is, according to the electric motor, even when the winding amount of the coil 24 is increased at the root portion 23A of the teeth 23, the coil end can be formed in a shape that does not protrude at the root portion.

  When the electric motor to which the present invention is applied is a linear motor 200 as shown in FIG. 2, a wide coil arrangement space can be secured while securing appropriate cross-sectional areas A1 and A2 of the teeth 23. This makes it possible to increase the number of arrangements of the armatures 20 per unit length. Therefore, it is possible to provide a linear motor that generates a high thrust.

[Description of Modified Embodiment]
FIG. 13 is a perspective view showing an armature core 21A of the electric motor according to the modified embodiment, and FIG. 14 is a perspective view showing an armature 20A according to the modified embodiment. It is a top view which shows the state which was wound. The armature core 21A includes four teeth 23 arranged at a pitch of 90 ° in the θ direction, and four non-wound teeth 25 each of which is disposed between the teeth 23 and in which the coil 24 is not wound. I have. As described above, the teeth 23 have such a shape that the width in the θ direction is increased as approaching the back yoke 22 and the width in the z direction is decreased as approaching the back yoke 22.

  In some types of armatures, not all the teeth are wound with the coil 24, but non-wound teeth 25 in which the coil 24 is not wound are arranged between the normal teeth 23 in some cases. As shown in FIG. 14, the coil 24 is wound around the teeth 23, but the coil 24 is not wound around the unwound teeth 25. Thus, there is an advantage that the space required for insulation between the coils 24 can be reduced and the number of winding steps of the coils 24 can be reduced.

  In the case where such a tooth structure is adopted, the width of the non-wound tooth 25 in the θ direction is such that the root portion 25A is narrower than the distal end portion 25B. The width of the non-wound teeth 25 in the z direction is such that the root portion 25A is wider than the distal end portion 25B. That is, the non-wound tooth 25 has a circumferential width θ11 and an axial width z11 at the root portion 25A, a circumferential width θ12 and an axial width z12 at the distal end portion 25B, and θ11 <θ12, z11> z12. Have a relationship. This is the opposite relationship to the teeth 23 around which the coil 24 is wound.

  By setting the circumferential width and the axial width of the unwound teeth 25 as described above, the coil arrangement space between the normal teeth 23 and the unwound teeth 25 can be increased. That is, by making the circumferential width of the non-winding teeth 25 narrower toward the root portion 25A, the space between the teeth 23 and the non-winding teeth 25 can be widened. It can be used as a space to accommodate.

1 rotating motor 10 field element (rotor)
13 Permanent magnet 20, 20A Armature 21, 21A Armature core 22 Back yoke 23 Teeth 23A Root part 23B Tip part 24 Coil 242 Coil end 25 Non-wound tooth 30 Iron core piece (circumferential segment)
41, 42, 43 1st piece, 2nd piece, 3rd piece A1, A2 Cross-sectional area θ1, θ2 Circumferential width z1, z2 Axial width

Claims (5)

A field element with a permanent magnet,
An electric machine comprising: a cylindrical back yoke; a plurality of teeth protruding radially inward from the back yoke and arranged in a circumferential direction of the back yoke; and a plurality of coils wound around each of the teeth. With a child,
The teeth are
A base portion near the back yoke and a tip portion near the protruding end portion are provided,
While the cross-sectional area of the root portion and the cross-sectional area of the tip portion are substantially the same,
An electric motor having a shape in which the root portion increases the inner diameter of the coil along the circumferential direction of the back yoke and decreases the inner diameter of the coil along the axial direction of the back yoke as compared with the tip portion. And
The teeth have a circumferential width along the circumferential direction of the back yoke, and an axial width along the axial direction of the back yoke,
In the electric motor, wherein the circumferential width is such that the root portion is wider than the tip portion, and the axial width is that the root portion is narrower than the tip portion.
It is arranged between a plurality of teeth arranged in the circumferential direction, and further includes an unwound tooth in which the coil is not wound,
The circumferential width of the unwound tooth is such that the root portion is narrower than the tip portion, and the axial width of the unwound tooth is that the root portion is wider than the tip portion. Have an electric motor. The electric motor according to claim 1 ,
The electric motor, wherein the circumferential width is wider as approaching the back yoke, and the axial width is narrower as approaching the back yoke. The electric motor according to claim 1 or 2 ,
The back yoke is configured to form the cylindrical shape by a combination of a plurality of circumferential division pieces, each circumferential division piece integrally includes a part of the teeth,
Each of the circumferentially divided pieces is a combination of a first piece, a second piece, and a third piece further divided in the axial direction, and the third piece is provided between the first piece and the second piece. Is placed,
The first piece and the second piece have a shape in which the axial width is smaller at the root portion than at the tip portion,
The electric motor, wherein the third piece has a shape in which the axial width is constant from the root portion to the tip portion. The electric motor according to any one of claims 1 to 3 ,
An electric motor, wherein the electric motor is a linear motor in which a plurality of the armatures as stators are arranged in a movable axis direction of the field element as a mover. The electric motor according to any one of claims 1 to 3 ,
An electric motor, wherein the electric motor is a rotary electric motor.

Images