Electric motor

Abstract

An electric motor (1) comprises: an armature (2) which is provided with a cylindrical-shaped printed circuit board and in which a plurality of layers of the printed circuit board are laminated in the radial direction of the cylindrical shape; and a field magnet (3) which is disposed closer to the central axis (AX) of the cylindrical shape as compared to the armature (2). The printed circuit board has a plurality of coils arranged in the circumferential direction of the cylindrical shape. Each of the coils is composed of a linear conductor. When the width of the conductor on the printed circuit board is denoted by x, and the thickness of the conductor in the radial direction is denoted by y, a set of x and y is set to have a set of xopt which represents x and yopt which represents y, where the space factor of the conductor in a cross section perpendicular to the circumferential direction of the armature (2) becomes maximum.

Description

electric motor

[0001] The present disclosure relates to an electric motor in which a printed circuit board is used in an armature.

[0002] Conventionally, electric motors using a cylindrical printed circuit board as an armature have been known. Patent Document 1 discloses an electric motor using a cylindrically wound printed circuit board as an armature, in which a plurality of coils made of conductor patterns are formed on the printed circuit board.

[0003] Japanese Patent Application Laid-Open No. 2020-89207

[0004] It is known that armatures that use cylindrically wound printed circuit boards tend to have a smaller coil space factor than armatures that have an iron core and magnet wire wound around the iron core. The smaller the coil space factor, the higher the copper loss. Therefore, in electric motors that use printed circuit boards in their armatures, temperature rise due to heat generated by copper loss becomes an issue.

[0005] The present disclosure has been made in view of the above, and has an object to provide an electric motor that can reduce heat generation caused by copper loss.

[0006] In order to solve the above-mentioned problems and achieve the object, the electric motor according to the present disclosure includes a cylindrical printed circuit board, an armature in which multiple layers of the printed circuit board are stacked in the radial direction of the cylinder, and a field magnet arranged toward the central axis of the cylinder relative to the armature. The printed circuit board has multiple coils arranged in the circumferential direction of the cylinder. Each of the multiple coils is made of a linear conductor. The width of the conductor on the printed circuit board is defined as x, and the thickness of the conductor in the radial direction is defined as y. For the pair of x and y, x is defined as x that maximizes the space factor of the conductor in a cross section of the armature perpendicular to the circumferential direction. opt and y opt A set of is set.

[0007] The electric motor according to the present disclosure has the effect of reducing heat generation caused by copper loss.

[0008] FIG. 12 is a diagram showing a schematic configuration of the electric motor according to the first embodiment; FIG. 13 is an exploded view of the electric motor according to the first embodiment; FIG. 14 is a diagram showing a printed circuit board provided in the armature according to the first embodiment; FIG. 15 is a diagram showing a part of the coils provided in the armature according to the first embodiment; FIG. 16 is a cross-sectional view of the armature according to the first embodiment; FIG. 17 is a diagram showing an example of a process for manufacturing the armature according to the first embodiment; FIG. 18 is a cross-sectional view of the electric motor according to the first embodiment; FIG. 6 is a diagram showing an example. FIG. 1 is a diagram for explaining the configuration of an armature according to the third embodiment. FIG. 2 is a diagram for explaining the configuration of an armature according to the third embodiment. FIG. 1 is a diagram for explaining the arrangement of coils in an armature according to the third embodiment. FIG. 2 is a diagram for explaining the arrangement of coils in an armature according to the third embodiment. FIG. 3 is a diagram for explaining the arrangement of coils in an armature according to the third embodiment. FIG. 4 is a diagram for explaining the arrangement of coils in an armature according to the third embodiment.

[0009] Hereinafter, an electric motor according to an embodiment will be described in detail with reference to the drawings.

[0010] First Embodiment Fig. 1 is a diagram showing a schematic configuration of an electric motor 1 according to a first embodiment. Fig. 2 is an exploded view of the electric motor 1 according to the first embodiment. The electric motor 1 includes an armature 2 which is a stator, and a field 3 which is a rotor.

[0011] The armature 2 is cylindrical. The field 3 is columnar. The field 3 is arranged in a space surrounded by the armature 2. The central axis AX of the cylindrical armature 2 is also the central axis of the columnar field 3. In other words, the armature 2 and the field 3 are arranged coaxially. The field 3 is arranged on the central axis AX side of the armature 2. The field 3 rotates around the central axis AX. A shaft 4 is attached to the field 3, which transmits the power of the field 3 to the outside of the motor 1.

[0012] The armature 2 generates a magnetic field by energizing the coils of the armature 2. The field 3 rotates due to the interaction between the magnetic field generated by the armature 2 and the magnets of the field 3. In the following description, the direction of the central axis AX is referred to as the axial direction, the direction perpendicular to the central axis AX as the radial direction, and the direction revolving around the central axis AX as the circumferential direction. Arrows A, B, and C shown in FIG. 1 represent the radial direction, the axial direction, and the circumferential direction, respectively. The circumferential direction is also the rotational direction in which the field 3 rotates.

[0013] In the above description, the electric motor 1 includes the armature 2, which is the stator, and the field 3, which is the rotor. However, the electric motor 1 may include the armature 2, which is the rotor, and the field 3, which is the stator. When the armature 2 is the rotor and the field 3 is the stator, the field 3 is mechanically locked by an electromagnetic brake or the like. The armature 2 rotates due to the interaction between the magnetic field generated by the armature 2 and the magnet of the field 3. In Figures 1 and 2, the magnetic gap surfaces of the armature 2 and the field 3 are arranged on the inner diameter side. However, the magnetic gap surfaces of the armature 2 and the field 3 may also be arranged on the outer diameter side.

[0014] FIG. 3 is a diagram showing the printed circuit board 5 provided in the armature 2 according to the first embodiment. The armature 2 includes the printed circuit board 5 wound in a cylindrical shape. By winding the printed circuit board 5, multiple layers of the printed circuit board 5 are stacked in the radial direction in the armature 2. FIG. 3 shows in a plan view how the coils 7 are provided on the surface of the core substrate 6. The left-right direction in FIG. 3 corresponds to the circumferential direction, and the up-down direction in FIG. 3 corresponds to the axial direction. When the printed circuit board 5 is expanded from a cylindrical shape into a planar shape, the printed circuit board 5 has an elongated shape.

[0015] The printed circuit board 5 includes a core board 6, a plurality of coils 7 formed on the core board 6, and an insulating layer. Fig. 3 shows a portion of the printed circuit board 5 where two coils 7 are provided. The insulating layer will be described later. When the printed circuit board 5 is unfolded into a flat surface, the plurality of coils 7 are arranged in the longitudinal direction of the printed circuit board 5. When the printed circuit board 5 is wound into a cylindrical shape, the plurality of coils 7 are arranged in the circumferential direction.

[0016] In Fig. 3, coils 7 adjacent to each other in the circumferential direction are connected to each other by connecting wires 8. Fig. 3 shows an example in which the arrangement of the multiple coils 7 in the armature 2 is a so-called concentrated winding method. The arrangement of the multiple coils 7 in the armature 2 may also be a so-called distributed winding method.

[0017] FIG. 4 is a diagram showing a portion of the coil 7 provided in the armature 2 according to the first embodiment. FIG. 4 shows an enlarged view of the portion enclosed by the box IV in FIG. 3 . The coil 7 is made of a linear conductor 10. The conductor 10 constituting the coil 7 is patterned in a spiral shape on the core substrate 6. An empty space where no conductor 10 is provided is provided at the center of the spiral. In the following description, the empty space at the center of the coil 7 is referred to as the inner periphery. In the example shown in FIG. 3 , the inner periphery is a hexagonal region. The conductor 10 is arranged so as to wind around the inner periphery multiple times from a starting point adjacent to the inner periphery. In the example shown in FIG. 3 , the outer shape of the coil 7 is a hexagon. The portion enclosed by the box IV is a portion of the coil 7 where the conductor 10 extends in the axial direction.

[0018] In the example shown in Figure 4, the conductor 10 is arranged so as to wrap around the inner periphery three times. Figure 4 shows three linear portions of the conductor 10 that are parallel to each other. A space 9 is provided between adjacent linear portions on the core substrate 6 to insulate the linear portions from each other. The planar configuration of the coil 7 is not limited to the configuration shown in Figures 3 and 4 and may be any desired configuration. The outer shape of the coil 7 may be other than a hexagon, and may be an oval shape, for example. The conductor 10 may be arranged so as to wrap around the inner periphery more than three times.

[0019] Fig. 5 is a cross-sectional view of the armature 2 according to the first embodiment. The cross-section shown in Fig. 5 is taken along line V-V shown in Fig. 3. Fig. 5 shows a cross-section of a portion of the printed circuit board 5 wound into a cylindrical shape. The left-right direction in Fig. 5 corresponds to the circumferential direction, and the up-down direction in Fig. 5 corresponds to the radial direction. Fig. 6 is a diagram showing a portion of the armature 2 according to the first embodiment. Fig. 6 shows an enlarged view of the portion enclosed by frame VI shown in Fig. 5.

[0020] In the example shown in Figures 5 and 6, the coils 7 are provided on both sides of the core substrate 6. The printed circuit board 5 shown in Figures 5 and 6 corresponds to a so-called "double-sided mounting board." The insulating layer 11 is provided between the coils 7 arranged in the radial direction. The insulating layer 11 is, for example, an insulating sheet having adhesive properties. The insulating layer 11 may also be an adhesive sheet having insulating properties, or an adhesive having insulating properties.

[0021] 5 and 6, a coil 7, an insulating layer 11, and a plurality of layers 12 each having the coil 7 sandwiched therebetween are stacked between two core substrates 6. The number of layers 12 of the printed circuit board 5 stacked in the radial direction is designated as N. N is a positive integer. In the following description, N will also be referred to as the number of layers. In the example shown in FIG. 5, core substrates 6 are provided at both ends of the printed circuit board 5 in the radial direction, but an insulating layer 11 may be provided at at least one of the ends.

[0022] In the above description, the printed circuit board 5 is described as a "double-sided mounting board," but is not limited to this. The printed circuit board 5 may also be a "single-sided mounting board" or a "multi-layer mounting board." In a printed circuit board 5 that corresponds to a "single-sided mounting board," the coil 7 is mounted on only one of the two surfaces of the core substrate 6. In a printed circuit board 5 that corresponds to a "multi-layer mounting board," the coil 7 and insulating layers 11 are alternately stacked on the core substrate 6.

[0023] In the first embodiment, the portion of the conductor 10 that constitutes the coil 7 is formed with a constant width on the printed circuit board 5. In the following description, the width of the conductor 10 on the printed circuit board 5 is defined as x. The thickness of the conductor 10 in the radial direction is defined as y. The width of the portion of the coil 7 enclosed by the box IV shown in FIG. 3 is defined as W. The width of this portion of the coil 7 is the width in the circumferential direction. In the following description, W, which is the width of this portion of the coil 7, is also referred to as the slot width. The width of the space 9 in the circumferential direction is defined as c. The width of the space 9 in the circumferential direction can also be referred to as the distance between the conductors 10 in the coil 7 on the printed circuit board 5. The thickness of the core substrate 6 in the radial direction is defined as m, and the thickness of the insulating layer 11 in the radial direction is defined as h. The width of the inner periphery of each coil 7 is defined as a, and the distance between adjacent coils 7 is defined as b. The width of the inner periphery is the width in the circumferential direction. The distance between the coils 7 is the distance in the circumferential direction.

[0024] Fig. 7 is a diagram showing an example of a process for manufacturing the armature 2 according to the first embodiment. Fig. 7 schematically shows how the armature 2 made of a cylindrical printed circuit board 5 is formed by winding the printed circuit board 5 that has been formed in a flat, unfolded state. Note that the core board 6 or insulating layer 11 is present on the inner surface of the cylindrical shape of the printed circuit board 5, but in Fig. 7, the core board 6 or insulating layer 11 on this surface is omitted. In the above description, the outer shape of the coil 7 is described as being hexagonal, but in Fig. 7, the outer shape of the coil 7 is simplified to be an oval shape.

[0025] Each of the components of the printed circuit board 5 is required to have flexibility so as not to be broken when the printed circuit board 5 is wound. Furthermore, each of the components of the printed circuit board 5 is required to have electrical characteristics such as insulation performance that do not change significantly when the printed circuit board 5 is wound. Note that the armature 2 is not limited to being formed by winding the printed circuit board 5. The armature 2 may also be formed by mounting the coil 7 on a core substrate 6 that has been formed into a cylindrical shape in advance.

[0026] Fig. 8 is a cross-sectional view of the electric motor 1 according to the first embodiment. The cross-section shown in Fig. 8 is perpendicular to the axial direction and is taken at the center of the armature 2 in the axial direction. In the following description, the outer diameter of the armature 2 is denoted as D, and the inner diameter of the armature 2 is denoted as d. Both the outer diameter D and the inner diameter d are assumed to be diameters. The number of slots in the armature 2, which are areas in which the coils 7 are arranged, is denoted as n, and the number of turns of the coils 7 per slot is denoted as T. The number of slots in the armature 2 is determined by the specifications of the electric motor 1.

[0027] FIG. 9 is a first diagram illustrating the number of slots in the armature 2 according to the first embodiment. FIG. 10 is a second diagram illustrating the number of slots in the armature 2 according to the first embodiment. Here, the numbering of slots is unified between the case where the arrangement of the multiple coils 7 is concentrated winding and the case where the arrangement of the multiple coils 7 is distributed winding. FIG. 9 schematically illustrates the arrangement of the coils 7 in the case of concentrated winding. FIG. 10 schematically illustrates the arrangement of the coils 7 in the case of distributed winding. FIGS. 9 and 10 illustrate regions where the coils 7 are arranged for each of the U phase, V phase, and W phase. Marks in each region indicate the current flow direction of the coils 7. The same marks indicate the same current flow direction. Different marks indicate opposite current flow directions.

[0028] In the case of concentrated winding shown in Fig. 9, coils 7 are arranged in two circumferentially adjacent regions, with current flowing in opposite directions. In the case of concentrated winding, each of these regions is considered a slot. Fig. 9 shows region 13, which is an example of one slot.

[0029] In the case of distributed winding shown in Figure 10, regions in which the current flows in the same direction are adjacent in the circumferential direction. For each phase, two regions in which the current flows in opposite directions are arranged across multiple regions. In the case of distributed winding, each of these regions is called a slot. Figure 10 shows region 13, which is an example of one slot.

[0030] Next, a first method, which is one of the methods for determining the width x and thickness y, will be described. FIG. 11 is a diagram showing an example of the relationship between the width of the conductor 10 in the armature 2 according to the first embodiment and the space factor of the conductor 10 in the slot. FIG. 11 shows a graph representing the relationship between the width x of the conductor 10 and the space factor of the conductor 10. In FIG. 11, the vertical axis represents the space factor, and the horizontal axis represents the width x. Due to manufacturing constraints of the printed circuit board 5, the thickness y of the conductor 10 is set to a value between 0.03 mm and 0.12 mm. FIG. 11 shows a graph representing the relationship between the width x and the space factor when the thickness y is in the range of 0.03 mm or more and 0.12 mm or less.

[0031] The pair of x and y is x, which maximizes the space factor of the conductor 10 in the cross section perpendicular to the circumferential direction of the armature 2. opt and y opt In the graph shown in FIG. 11, x when the space factor is maximum is set as x opt Since y is a thickness that falls within the range of 0.03 mm to 0.12 mm, y opt is a thickness comprised between 0.03 mm and 0.12 mm.

[0032] Here, we will explain in detail the theoretical calculation formula that expresses the relationship between the width x of the conductor 10 and the space factor of the conductor 10. The width x can be derived by determining the slot width W. The slot width W is expressed by the following formula (1) based on the design specifications of the printed circuit board 5.

[0033]

[0034] The slot width W is expressed by the following equation (2) based on the dimensions of each part of the armature 2.

[0035]

[0036] Combining equations (1) and (2), the width x is expressed by the following equation (3).

[0037]

[0038] Regarding the width a of the inner periphery, in the case of concentrated winding, a = a is substituted into equation (3), and in the case of distributed winding, a = 0 is substituted into equation (3).

[0039] When determining the width x of the conductor 10, it is necessary to determine the number of layers N of the armature 2. The number of layers N can be determined by determining the thickness y of the conductor 10. The thickness y is expressed by the following equation (4).

[0040]

[0041] As described above, the thickness y is within the range of 0.03 mm or more and 0.12 mm or less due to manufacturing constraints of the printed circuit board 5. The number of layers N is a positive integer. By increasing or decreasing the value of the number of layers N, it is possible to determine the number of layers N when the value of y is within the range of 0.03 mm or more and 0.12 mm or less. Once the thickness y and the number of layers N are determined, the width x can be determined using equation (3).

[0042] Fig. 12 is a cross-sectional view of a slot in the armature 2 according to the first embodiment. Fig. 13 is a view of only the cross section of the conductor 10 taken out from the cross section shown in Fig. 12. Fig. 12 shows a cross section of a region 13 which is one slot.

[0043] The cross-sectional area S of the conductor 10 in the slot is expressed by the following equation (5): By determining the width x and thickness y, the cross-sectional area S can be derived.

[0044]

[0045] From equations (3) to (5), it can be seen that the cross-sectional area S is determined by determining the number of layers N.

[0046] The printed circuit board 5 is formed by giving the conductor 10 a width x and a thickness y that maximizes the cross-sectional area S, thereby maximizing the space factor of the conductor 10 in the slot.opt and thickness y opt and maximize the space factor of the conductor 10, thereby reducing the electrical resistance of the conductor 10 and the loss of the conductor 10. This allows the motor 1 to reduce copper loss and the heat generation caused by copper loss.

[0047] So far, we have explained the first method, which is one method for determining the width x and thickness y. Next, we will explain the second method, which is another method for determining the width x and thickness y. In the second example, the electric motor 1 is made up of one or more unit structures. Here, a set of a certain number of magnetic poles and a certain number of slots, each set consisting of magnetic poles provided in the field 3 and slots that are regions in which the coils 7 are arranged in the armature 2, is referred to as a unit structure of the electric motor 1.

[0048] FIG. 14 is a diagram for explaining a unit structure 15 of the electric motor 1 according to the first embodiment. FIG. 14 schematically shows a portion of the armature 2 that constitutes one unit structure 15 and a portion of the field 3 that constitutes one unit structure 15. The left-right direction in FIG. 14 corresponds to the circumferential direction, and the up-down direction in FIG. 14 corresponds to the radial direction. In the portion of the armature 2 that constitutes one unit structure 15, multiple slots are arranged in the circumferential direction. A rectangle 16 shown in FIG. 14 represents one of the multiple slots. In the portion of the field 3 that constitutes one unit structure 15, multiple magnetic poles are arranged in the circumferential direction. A rectangle 17 shown in FIG. 14 represents one of the multiple magnetic poles.

[0049] For example, suppose the total number of magnetic poles in the entire motor 1 is six, and the total number of slots in the entire motor 1 is nine. In this case, each unit structure 15 of the motor 1 is a set of two magnetic poles and three slots, and the motor 1 is made up of three unit structures 15. Note that the number of magnetic poles and the number of slots in a unit structure 15 are arbitrary. Also, the number of unit structures 15 that the motor 1 has is arbitrary. In the following explanation, the number of slots in a unit structure 15 is n', the circumferential length of the portion of the armature 2 that constitutes the unit structure 15 is L, and the radial length of the slot is H.

[0050] In the second method, as in the first method, the slot width W is determined, and the width x opt and thickness y opt In addition, the formula (1) also holds in the second method.

[0051] The slot width W is expressed by the following equation (6) based on the dimensions of each part of the armature 2.

[0052]

[0053] Combining equations (1) and (6), the width x is expressed by the following equation (7).

[0054]

[0055] Regarding the width a of the inner periphery, in the case of concentrated winding, a = a is substituted into equation (7), and in the case of distributed winding, a = 0 is substituted into equation (7).

[0056] The thickness y is expressed by the following formula (8).

[0057]

[0058] By increasing or decreasing the value of the number of layers N, it is possible to determine the number of layers N when the value of y is included in the range of 0.03 mm or more and 0.12 mm or less. By determining the thickness y and the number of layers N, it is possible to determine the width x using equation (7). By determining the width x and thickness y, it is possible to derive the cross-sectional area S.

[0059] The printed circuit board 5 is formed by giving the conductor 10 a width x and a thickness y that maximizes the cross-sectional area S, thereby maximizing the space factor of the conductor 10 in the slot. opt and thickness y opt and maximize the space factor of the conductor 10, thereby reducing the electrical resistance of the conductor 10 and the loss of the conductor 10. This allows the motor 1 to reduce copper loss and the heat generation caused by copper loss.

[0060] Second Embodiment Fig. 15 is a cross-sectional view of an armature 2 according to a second embodiment. In the second embodiment, a configuration different from that of the first embodiment will be mainly described. Fig. 15 shows a cross-section of a portion of a printed circuit board 5 wound into a cylindrical shape. The left-right direction in Fig. 15 corresponds to the circumferential direction, and the up-down direction in Fig. 15 corresponds to the radial direction. The configuration shown in Fig. 15 is the same as the configuration shown in Fig. 5. The cross-section of the region of the armature 2 that is a slot is the same as the cross-section shown in Fig. 6. In the second embodiment, the multiple coils 7 are arranged by concentrated winding.

[0061] In the configuration shown in Fig. 15, the width of the inner periphery of each coil 7 is a', and the distance between adjacent coils 7 is b'. The width of the inner periphery is the width in the circumferential direction. The distance between coils 7 is the distance in the circumferential direction. In the second embodiment, the pair of a' and b' includes a' that maximizes the winding factor of the coil 7. opt and b', opt A set of is set.

[0062] The copper loss generated in the motor 1 is basically the winding factor k w It is known that the winding factor k is inversely proportional to w is a coefficient determined by the combination of the number of magnetic poles of the motor 1 and the number of slots of the motor 1, or the arrangement of the multiple coils 7 in the motor 1. The copper loss of the motor 1, which is a three-phase motor, is calculated by multiplying the phase resistance R p and the square of the phase current. w The larger the winding factor k, the larger the induced voltage of the motor 1. w The larger the phase current required to output the same torque is, the smaller the phase current is.

[0063] Here, the winding factor k w The component proportional to the square of the reciprocal of is extracted, and the extracted component is used as the copper loss coefficient k Cu Copper loss coefficient k Cu is expressed by the following equation (9).

[0064]

[0065] Furthermore, the winding factor kw is the short pitch winding coefficient k p It is known that the short pitch winding coefficient k p is a coefficient that indicates the ratio of the reduction in the interlinkage magnetic flux when the slot pitch and the magnetic pole pitch are different from each other. w Although it is proportional to the above, the details are omitted here.

[0066] 16 is a diagram for explaining the relationship between the arrangement of the coils 7 in the armature 2 according to the second embodiment and the winding factor. In the graph shown in FIG. 16, the vertical axis represents the winding factor k w 16, the horizontal axis represents the electrical angle θ of the coil 7 and the width x of the conductor 10. The configuration of the coil 7 is shown schematically above the graph in FIG.

[0067] The short pitch winding factor k of the motor 1 having the armature 2 shown in FIG. p can be derived from the amount of magnetic flux linking with the coil 7 at each of the inner peripheral position P1 and the outer peripheral position P2 of the coil 7. The inner peripheral position P1 is a position on the inner circumference of the coil 7 that is in contact with the inner peripheral part. The outer peripheral position P2 is a position on the outer circumference of the coil 7. The amount of magnetic flux linking in the coil 7 is small at each of the inner peripheral position P1 and the outer peripheral position P2, and is maximum midway between the inner peripheral position P1 and the outer peripheral position P2. The ratio of the amount of magnetic flux generated by the magnet to the amount of magnetic flux linking is the short-pitch winding factor k p The magnetic flux of each magnet is equivalent to φ magnet , the maximum value of the magnetic flux linkage in each slot is φ n _ max , the electrical angle at the inner peripheral position P1 of the coil 7 of each phase is θ1, and the electrical angle at the outer peripheral position P2 of the coil 7 of each phase is θ2, and the short pitch winding coefficient k p is expressed by the following equation (10).

[0068]

[0069] The electrical angle θ1 is expressed by the following equation (11) based on the configuration shown in Fig. 15. The electrical angle θ2 is expressed by the following equation (12) based on the configuration shown in Fig. 15. Let p be the number of magnetic poles applied to the motor 1, and τ be the pitch at which the multiple magnetic poles are arranged. pLet's say.

[0070]

[0071]

[0072] From equations (9) to (12), the width a' and the distance b' are respectively the copper loss coefficient k Cu It is known to be related to.

[0073] 17 is a diagram showing an example of the relationship between the width of the inner circumferential portion of each coil 7 and the copper loss coefficient for the electric motor 1 according to the second embodiment. The vertical axis of the graph shown in FIG. 17 represents the copper loss coefficient k Cu The horizontal axis of the graph represents the width a' of the inner periphery. FIG. 17 shows the relationship between the width a' and the copper loss coefficient k for the cases where the value of the distance b' between the adjacent coils 7 is 0, 1, 2, and 3. Cu 10 shows a graph showing the relationship between

[0074] According to FIG. 17, the smaller the value of the distance b', the greater the copper loss coefficient k Cu is small. Copper loss coefficient k Cu 17, the copper loss coefficient k Cu There exists a value of the width a' that makes the copper loss coefficient k Cu The combination of width a' and distance b' when is the minimum value is the winding factor k of the coil 7. w a' that maximizes opt and b' opt This is a set of:

[0075] According to Figure 17, as the width a' approaches 0, the area of ​​the portion of the coil 7 facing the magnet increases, and the amount of magnetic flux linkage in the coil 7 increases. When the amount of magnetic flux linkage in the coil 7 increases, the short-pitch winding factor k p becomes larger, and the copper loss coefficient k Cu becomes smaller. When the width a' is p When the winding frequency is increased to about 1 / 2, the coil 7 is no longer located at the position where the density of the magnetic flux from the magnet is maximum, so the short-pitch winding factor k p Therefore, the width a' is significantly reduced. opt It is desirable that the following equation (13) be satisfied.

[0076]

[0077] Width a' opt The above explanation for the distance b' opt The same can be said for the case where the distance b' is calculated by taking into account the range of values ​​that the electrical angle θ2 can take in equation (12). opt It is desirable that the following equation (14) be satisfied.

[0078]

[0079] Winding factor k of coil 7 w The width a' when maximizing opt and distance b' opt By forming the plurality of coils 7 so as to satisfy the width a', the copper loss of the electric motor 1 is reduced. opt satisfies equation (13) and the distance b' opt By satisfying equation (14), the copper loss coefficient k Cu This can reduce the copper loss of the motor 1, thereby further reducing the copper loss of the motor 1. As a result, the motor 1 can reduce the copper loss and the heat generation caused by the copper loss.

[0080] Third Embodiment Fig. 18 is a first diagram for explaining the configuration of an armature 2 according to a third embodiment. Fig. 19 is a second diagram for explaining the configuration of an armature 2 according to the third embodiment. In the third embodiment, the configuration different from the first or second embodiment will be mainly explained.

[0081] 18 and 19 schematically show how the planar printed circuit board 5 is wound into a cylindrical shape. In FIGS. 18 and 19, the coil portion 14 represents a portion of the layer 12 having two coils 7 stacked with the insulating layer 11 interposed therebetween. The coil portion 14 is the region of the layer 12 where the coils 7 are formed, and can be said to be the region that forms the slot. In FIGS. 18 and 19, the core substrate 6 is shown in a simplified form. The insulating layer 11 is not shown in FIGS. 18 and 19. In the third embodiment, the multiple coils 7 are arranged by concentrated winding.

[0082] By winding the printed circuit board 5 into a cylindrical shape, an armature 2 having N layers 12 is formed. In the third embodiment, N is an integer equal to or greater than 2. In each slot of the armature 2, it is desirable that a plurality of coil portions 14 are arranged radially. However, if all of the plurality of coils 7 on the core substrate 6 are arranged at a constant distance b, there will be a deviation in the position of the coil portions 14 in the circumferential direction in each slot. This deviation in the position of the coil portions 14 will result in the slot having a shape that differs from the ideal shape. The ideal shape of the slot is the shape when the coils 7 of each layer 12 in the slot are arranged radially.

[0083] Here, M is an integer equal to or greater than 1 and less than N. The distance b" is defined as the distance between the coil 7 closest to the end of the winding of the cylindrical shape in the Mth layer 12 from the central axis AX of the cylindrical shape among the multiple layers 12 of the printed circuit board 5 and the coil 7 closest to the start of the winding of the cylindrical shape in the (M+1)th layer 12 from the central axis AX of the cylindrical shape among the multiple layers 12 of the printed circuit board 5. In FIGS. 18 and 19 , the distance b" is defined as the distance between the coil portion 14 closest to the end of the winding of the cylindrical shape in the Mth layer 12 and the coil portion 14 closest to the start of the winding of the cylindrical shape in the (M+1)th layer 12. If the length of the distance b" is the same as the length of the distance b between the coils 7 on each of the multiple layers 12 of the printed circuit board 5, then theoretically the position of the coil 7 on the (M+1)th layer 12 will be shifted circumferentially relative to the coil 7 on the Mth layer 12.

[0084] In the third embodiment, as shown in FIG. 18 , the position of the coil 7 on the core substrate 6 is determined so that the distance b″ is longer than the distance b. By making the distance b″ longer than the distance b, it is possible to eliminate misalignment of the coil 7 on the (M+1)th layer 12 with respect to the coil 7 on the Mth layer 12. In other words, the coil 7 on the (M+1)th layer 12 and the coil 7 on the Mth layer 12 can be aligned in the radial direction. FIG. 19 shows how the coil portion 14 on the Mth layer 12 and the coil portion 14 on the (M+1)th layer 12 are aligned in the radial direction by bending the core substrate 6 at the distance b″ from the state shown in FIG. 18 . In this way, by making the distance b″ longer than the distance b and adjusting the position of the coil portion 14 in the circumferential direction, the coil portion 14 on one layer 12 and the coil portion 14 on the outer circumferential side of that layer 12 can be aligned in the radial direction. By arranging the coil portions 14 in the radial direction between layers 12 that are adjacent to each other in the radial direction, it is possible to obtain a slot with an ideal shape.

[0085] In the third embodiment, the distance b'' satisfies the following equation (15).

[0086]

[0087] Here, the process of deriving equation (15) will be described. Fig. 20 is a first diagram for explaining the arrangement of the coils 7 in the armature 2 according to the third embodiment. Fig. 21 is a second diagram for explaining the arrangement of the coils 7 in the armature 2 according to the third embodiment.

[0088] 20 and 21, the coil portion 14 nM is the nMth coil portion 14 from the start of winding on the printed circuit board 5. nM is the coil portion 14 of the Mth layer 12 that is closest to the end of the cylindrical winding. nM+1 is the (nM+1)th coil portion 14 from the start of winding on the printed circuit board 5. nM+1 is the coil portion 14 in the (M+1)th layer 12 that is closest to the start of winding of the cylindrical shape. n(M-1)+1is the {n(M-1)+1}th coil portion 14 from the start of winding on the printed circuit board 5. n(M-1)+1 is the coil portion 14 of the (M-1)th layer 12 that is closest to the start of winding of the cylindrical shape.

[0089] FIG. 20 shows the case where the distance b" satisfies the formula (15) and the length of the distance b" is the shortest, that is, the length of the distance b" is the same as the length of the distance b. In this case, the coil portion 14 nM+1 and coil portion 14 nM are arranged on the same circle centered on the central axis AX. In the above explanation, if the length of distance b" is the same as the length of distance b, then theoretically, the position of the coil 7 on the (M+1)th layer 12 is shifted circumferentially relative to the coil 7 on the Mth layer 12. However, when the printed circuit board 5 is wound into a cylindrical shape, the cylindrical shape may expand in the radial direction, or the printed circuit board 5 may be deformed due to tension applied to the printed circuit board 5. Even if the length of distance b" is the same as the length of distance b, the coil 7 on the (M+1)th layer 12 and the coil 7 on the Mth layer 12 may become aligned in the radial direction due to the expansion of the cylindrical shape or deformation of the printed circuit board 5. For this reason, the case where distance b" is equal to distance b is included in equation (15).

[0090] FIG. 21 shows the case where distance b'' satisfies equation (15) and is the longest.

[0091] Fig. 22 is a third diagram for explaining the arrangement of the coils 7 in the armature 2 according to the third embodiment. Fig. 23 is a fourth diagram for explaining the arrangement of the coils 7 in the armature 2 according to the third embodiment. Fig. 24 is a fifth diagram for explaining the arrangement of the coils 7 in the armature 2 according to the third embodiment.

[0092] FIG. 22 shows the coil portion 14 of the armature 2 when the distance b'' is the longest. n(M-1)+1 , 14 nM , 14 nM+1 The equation on the right side of "<" in equation (15) represents the arrangement of the coil unit 14. n(M-1)+1and coil portion 14 nM and are arranged on the same circle centered on the central axis AX.

[0093] The triangle shown in FIG. 23 corresponds to the coil portion 14 in FIG. n(M-1)+1 , 14 nM+1 and coil portion 14 nM The triangle shown in FIG. 23 has a first side with a length of distance b", a second side with a length of distance b, and a third side with a length of h+yf+2m. In FIG. 23, angle θ is the angle between the second side and the third side, i.e., the angle of the diagonal of the first side.

[0094] The distance b'' is expressed by the following equation (16).

[0095]

[0096] The radius r is the radius of a circle centered on the central axis AX, and each coil portion 14 n(M-1)+1 , 14 nM is the radius of the circle representing the position where the triangle is located. The angle θ' shown in Figure 24 is the angle of the angle that appears when the third side of the triangle shown in Figure 23 is extended toward the central axis AX, and is the supplementary angle of the angle between the second side and the third side. The angle θ' is expressed by the following equation (17).

[0097]

[0098] Coil portion 14 in the circumferential direction relative to the central axis AX n(M-1)+1 a line passing through the center of the coil portion 14 in the circumferential direction relative to the central axis AX nM The angle between the line passing through the center of the coil portion 14 and the slot width W can be expressed using the radius r. From this, the angle θ' can be expressed by the following equation (18).

[0099]

[0100] 25 is a sixth diagram for explaining the arrangement of the coils 7 in the armature 2 according to the third embodiment. In FIG. 25, N coil portions 14 constituting one slot are shown. n1 , 14 n2 , ..., 14 nM , ..., 14nN Coil section 14 n1 is the coil portion 14 of the first layer 12. n2 is the coil section 14 of the second layer 12. nM is the coil portion 14 of the Mth layer 12. nN is the coil portion 14 of the Nth layer 12. The radial length of one layer 12 is expressed as (D−d) / 2N. The radius r is expressed by the following equation (19).

[0101]

[0102] By substituting equations (17) to (19) into equation (16), the equation to the right of "<" in equation (15) is obtained. However, due to the expansion of the cylindrical shape or deformation of the printed circuit board 5 caused by winding the printed circuit board 5 into a cylindrical shape, it can be said that the expected situation in which the distance b" is equal to the equation to the right of "<" in equation (15) does not occur. For this reason, equation (15) excludes the case in which the distance b" is equal to the equation to the right of "<" in equation (15).

[0103] In the third embodiment, the distance b'' satisfies the formula (15), so that the coil portions 14 can be arranged in the radial direction in the layers 12 that are adjacent to each other in the radial direction. This makes it possible to obtain an armature 2 having slots with an ideal shape.

[0104] Fourth Embodiment Fig. 26 is a cross-sectional view of a portion of an armature 2 according to a fourth embodiment. Fig. 26 shows a cross-section of an area 13, which is an example of one slot. In the fourth embodiment, a configuration different from those of the first to third embodiments will be mainly described. The cross-section shown in Fig. 26 is a cross-section perpendicular to the central axis AX. Fig. 26 shows N coil portions 14. In the fourth embodiment, N is an integer of 2 or more.

[0105] In manufacturing the armature 2, the ideal shape of the slot in the cross section shown in Fig. 26 is a shape close to a trapezoid. In the fourth embodiment, the length of the coil portion 14 in the circumferential direction is longer on the outer circumferential side of the cylindrical shape than on the inner circumferential side of the cylindrical shape, so that the slot has a shape close to the ideal shape.

[0106] Fig. 27 is a cross-sectional view of the coil portion 14 in the armature 2 according to the fourth embodiment. The cross section shown in Fig. 27 is perpendicular to the central axis AX.

[0107] The circumferential width of the end of the coil portion 14, which is the region of the layer 12 where the coil 7 is formed, on the side of the central axis AX is defined as W1, and the circumferential width of the end of the coil portion 14 opposite the central axis AX is defined as W2. W1 and W2 satisfy the following equation (20):

[0108]

[0109] In each coil portion 14 constituting the slot, the width W2 is approximately 0% to 5% longer than the width W1. This allows for a slot with an ideal shape that is close to a trapezoid. By making the slot have an ideal shape, deformation of the armature 2 during manufacturing can be reduced.

[0110] Fifth Embodiment Fig. 28 is a cross-sectional view of the coil portion 14 in the armature 2 according to a fifth embodiment. The cross section shown in Fig. 28 is a cross section perpendicular to the central axis AX. In the fifth embodiment, the configuration different from the first to fourth embodiments will be mainly described.

[0111] Let W1 be the circumferential width of the end of coil portion 14, which is the region of layer 12 where coil 7 is formed, on the side of central axis AX, W2 be the circumferential width of the end of coil portion 14 opposite central axis AX, and W3 be the circumferential width of the center of coil portion 14 in the radial direction. W1 and W3 satisfy the following formula (21). W2 and W3 satisfy the following formula (22).

[0112]

[0113]

[0114] The width W3 can be considered to be the representative width of the coil portion 14 in the circumferential direction. By making the width W1 shorter than the representative width W3 and making the width W2 longer than the representative width W3, it is possible to obtain a slot with an ideal shape that is close to a trapezoid. By making the slot have an ideal shape, it is possible to reduce deformation of the shape of the armature 2 when manufacturing the armature 2.

[0115] Sixth Embodiment Fig. 29 is a schematic diagram of a printed circuit board 5 constituting an armature 2 according to a sixth embodiment. In the sixth embodiment, configurations different from those of the first to fifth embodiments will be mainly described. In the sixth embodiment, pins 21 are provided on one surface of the core substrate 6, extending in the radial direction. Holes 22 are formed on the other surface of the core substrate 6. The holes 22 are shaped so that the pins 21 can be fitted into them. Fig. 29 shows a portion of the core substrate 6 where two coils 7, one pin 21, and one hole 22 are provided. The pins 21 and the hole 22 are provided in an area of ​​the core substrate 6 other than the area where the coils 7 are formed.

[0116] When the printed circuit board 5 is wound into a cylindrical shape, the positioning error of the coil 7 that constitutes the slot can be reduced, allowing the slot to approach an ideal shape. In the sixth embodiment, when the printed circuit board 5 is wound and the multiple layers 12 are stacked, the pins 21 are fitted into the holes 22. The positional relationship between the pins 21 and the holes 22 is set so that the pins 21 can be fitted into the holes 22 when the printed circuit board 5 is wound and the multiple layers 12 are stacked. An area for providing the pins 21 and the holes 22 is secured in the core substrate 6 at a position axially relative to the area where the coil 7 is formed. This prevents the printed circuit board 5 from becoming longer in the circumferential direction, and allows the pins 21 and the holes 22 to be provided without reducing the space factor.

[0117] The radial length of the pin 21 is longer than the thickness y of the coil 7. The radial depth of the hole 22 is deeper than the difference between the radial length of the pin 21 and the thickness y. The shape of the pin 21 is not limited to the cylindrical shape shown in FIG. 29 . The shape of the pin 21 may be any shape that can reduce the placement error of the coil 7, and may be an elongated cylindrical shape with the axial or circumferential direction as the longitudinal direction. The hole 22 has a shape that matches the shape of the pin 21. The positional relationship between the pin 21 and the hole 22 may be any shape that can reduce the placement error of the coil 7. The position of the hole 22 may be shifted in the axial or circumferential direction relative to the position of the pin 21.

[0118] The pins 21 may be made of any material. The pins 21 may be made of the same material as one of the components of the printed circuit board 5, or may be made of a material that is not used for the components of the printed circuit board 5. The pins 21 may be joined when the components of the printed circuit board 5 are mounted, or may be added after the components of the printed circuit board 5 have been mounted.

[0119] By fitting the pins 21 into the holes 22 when the armature 2 is manufactured, it is possible to reduce the positioning error of the coils 7 that form the slots, thereby preventing a decrease in the performance of the electric motor 1.

[0120] Seventh Embodiment Fig. 30 is a schematic diagram of a printed circuit board 5 constituting an armature 2 according to a seventh embodiment. In the seventh embodiment, configurations different from those of the first to sixth embodiments will be mainly described. In the seventh embodiment, a plurality of coils 7 are provided on one surface of a core substrate 6. The other surface of the core substrate 6 is formed with recesses 23 shaped to allow the coils 7 to be fitted therein. Fig. 30 shows a portion of the core substrate 6 where two coils 7 and two recesses 23 are provided.

[0121] In the seventh embodiment, when the printed circuit board 5 is wound and the layers 12 are stacked, the coil 7 is fitted into the recess 23. The recess 23 has a shape that matches the shape of the coil 7. The position of the recess 23 is set so that the coil 7 can be fitted into the recess 23 when the printed circuit board 5 is wound and the layers 12 are stacked.

[0122] By fitting the coil 7 into the recess 23 when the armature 2 is manufactured, it is possible to reduce positioning errors of the coil 7 that constitute the slot. This makes it possible to prevent a decrease in performance of the electric motor 1. In the seventh embodiment, the area of ​​the portion of the core substrate 6 that comes into contact with the coil 7 is larger than in the sixth embodiment. Therefore, in the seventh embodiment, the coefficient of heat transfer between the stacked layers 12 is improved compared to the sixth embodiment. With the improved coefficient of heat transfer between the stacked layers 12, the electric motor 1 can reduce the temperature rise of the coil 7 when current is applied.

[0123] Eighth embodiment Fig. 31 is a diagram showing a schematic configuration of a printed circuit board 5 constituting an armature 2 according to an eighth embodiment. In the eighth embodiment, configurations different from those of the first to seventh embodiments will be mainly described. Fig. 31 shows a part of the cylindrical printed circuit board 5 when the printed circuit board 5 is developed into a plane.

[0124] In the eighth embodiment, the positions of the coils 7 in the circumferential direction are shifted for each of the multiple layers 12. With this configuration, the electrical angles of the coils 7 adjacent to each other in the radial direction are different. Fig. 31 shows the coils 7 provided in one layer 12. For reference, in Fig. 31, the coils 7 of the layer 12 arranged on the far side of the layer 12 in question are indicated by dashed lines.

[0125] FIG. 32 is a cross-sectional view of a portion of the armature 2 according to the eighth embodiment. FIG. 32 shows a cross-section of region 13, which is an example of one slot. The cross-section shown in FIG. 32 is perpendicular to the central axis AX. The left-right direction in FIG. 32 corresponds to the circumferential direction, and the up-down direction in FIG. 32 corresponds to the axial direction. As shown in FIG. 32 , the position of the coil 7 in the circumferential direction is shifted for each position in the radial direction. A plurality of coils 7 are mounted on the printed circuit board 5 so that the position of the coil 7 in the circumferential direction is shifted for each position in the radial direction.

[0126] The coils 7 are circumferentially shifted for each layer 12, thereby forming a so-called skewed armature 2. This allows the motor 1 to reduce torque ripple in the driving direction of the motor 1 or thrust ripple in the driving direction of the motor 1.

[0127] The configurations shown in the above embodiments are examples of the contents of the present disclosure. The configurations of each embodiment can be combined with other known technologies. The configurations of each embodiment can also be combined as appropriate. Part of the configuration of each embodiment can be omitted or modified without departing from the gist of the present disclosure.

[0128] REFERENCE SIGNS LIST 1 electric motor, 2 armature, 3 field, 4 shaft, 5 printed circuit board, 6 core board, 7 coil, 8 jumper wiring, 9 space, 10 conductor, 11 insulating layer, 12 layer, 13 area, 14, 14 n1 , 14 n2 , 14 n(M-1)+1 , 14 nM , 14 nM+1 , 14 nN Coil portion, 15 unit structure, 16, 17 rectangle, 21 pin, 22 hole, 23 recess, AX central axis.

Claims

1. A cylindrical printed circuit board is provided with an armature in which a plurality of layers of the printed circuit board are stacked in the radial direction of the cylindrical shape, and a field magnet is arranged toward the central axis of the cylindrical shape with respect to the armature, the printed circuit board has a plurality of coils arranged in the circumferential direction of the cylindrical shape, each of the plurality of coils being made of a linear conductor, the width of the conductor on the printed circuit board is x, and the thickness of the conductor in the radial direction is y, and the set of x and y includes x that maximizes the space factor of the conductor in a cross section of the armature perpendicular to the circumferential direction. opt and y, opt A motor characterized in that a set of is set.

2. The printed circuit board comprises a core board on which a plurality of the coils are formed, and an insulating layer provided between the coils in a plurality of the layers, and c is the distance between the conductors in the coils on the printed circuit board, f is the number of the conductors formed in each layer of the printed circuit board, h is the thickness of the core board in the radial direction, m is the thickness of the insulating layer in the radial direction, n is the number of slots in the armature that are areas in which the coils are arranged, T is the number of turns of the coil per slot, N is the number of layers of the printed circuit board stacked in the radial direction in the armature, D is the outer diameter of the armature, d is the inner diameter of the armature, and a is the width in the radial direction of the inner periphery that is the space at the center of the coils, opt satisfies the following formula (1), opt The electric motor according to claim 1, characterized in that: satisfies the following formula (2).

3. A motor is composed of one or more unit structures, each of which is a set of magnetic poles provided in the field magnet and slots in the armature, which are regions in which the coils are arranged, and each set of a certain number of magnetic poles and a certain number of slots is defined as a unit structure of the motor, and the printed circuit board comprises a core board on which a plurality of the coils are formed, and an insulating layer provided between the coils in a plurality of the layers, and the distance between the conductors in the coils on the printed circuit board is c, the number of the conductors formed in each layer of the printed circuit board is f, the thickness of the core board in the radial direction is h, the thickness of the insulating layer in the radial direction is m, the number of the slots in the unit structure is n', the number of turns of the coil per slot is T, the number of layers of the printed circuit board laminated in the radial direction in the armature is N, the length in the circumferential direction of the portion of the armature that constitutes the unit structure is L, the length in the radial direction of the slot is H, and the width in the radial direction of an inner periphery that is a space at the center of the coil is a a, opt satisfies the following formula (3), opt The electric motor according to claim 1, characterized in that: satisfies the following formula (4).

4. The above opt 4. The electric motor according to claim 1, wherein the thickness is comprised between 0.03 mm and 0.12 mm.

5. The coils are arranged by concentrated winding, and the width in the radial direction of the inner periphery, which is the space at the center of the coil, is a', and the distance between adjacent coils is b'. For the pair of a' and b', a' that maximizes the winding factor of the coil is a'. opt and b', opt The electric motor according to any one of claims 2 to 4, characterized in that a set of:

6. Let p be the number of magnetic poles applied to the motor, and τ be the pitch at which the magnetic poles are arranged. p As the a' opt satisfies the following formula (5), opt The electric motor according to claim 5, characterized in that: satisfies the following formula (6).

7. The electric motor according to claim 2 or 3, characterized in that the multiple coils are arranged using concentrated winding, and where M is an integer greater than or equal to 1 and less than N, b'' is the distance between the coil that is closest to the end of the winding of the cylindrical shape in the M-th layer from the central axis of the cylindrical shape among the multiple layers of the printed circuit board and the coil that is closest to the start of the winding of the cylindrical shape in the (M+1)-th layer from the central axis of the cylindrical shape among the multiple layers of the printed circuit board, b is the distance between the coils in each of the multiple layers of the printed circuit board, and W is the width of the slot in the circumferential direction, and b'' satisfies the following formula (7):

8. The electric motor described in claim 7, characterized in that the width in the circumferential direction of the end of the coil portion, which is the area in which the coil is formed in the layer, facing the central axis is defined as W1, and the width in the circumferential direction of the end of the coil portion opposite the central axis is defined as W2, and W1 and W2 satisfy the following formula (8).

9. An electric motor as described in claim 7 or 8, characterized in that the width in the circumferential direction of the end of the coil portion facing the central axis, which is the region in which the coil is formed in the layer, is W1, the width in the circumferential direction of the end of the coil portion opposite the central axis is W2, and the width in the circumferential direction of the center of the coil portion in the radial direction is W3, wherein W1 and W3 satisfy the following formula (9), and W2 and W3 satisfy the following formula (10).

10. An electric motor as described in any one of claims 1 to 4, characterized in that the printed circuit board comprises a core board on which a plurality of the coils are formed, one surface of the core board is provided with a pin standing in the radial direction, and the other surface of the core board is formed with a hole shaped to allow the pin to be fitted into.

11. An electric motor as described in any one of claims 1 to 4, characterized in that the printed circuit board comprises a core board on which a plurality of the coils are formed, the plurality of coils are provided on one surface of the core board, and the other surface of the core board is formed with recesses shaped so that the coils can be fitted into them.

12. An electric motor as set forth in any one of claims 1 to 4, characterized in that in a plurality of layers, the positions of the coils in the circumferential direction are shifted for each layer.

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