Axial flux stator core

Abstract

An axial flux stator core (50) and the manufacture thereof are presented. The axial flux stator core (50) has a helical layered structure (24), where the axial flux stator core (50) comprises a metal strip (14) having a longitudinal first side (16) and a longitudinal second side (18), and the metal strip is wound to form the helical layered structure (24). A first side (16) of the metal strip (14) has a plurality of slots (20) whose slot width varies along the metal strip (14), the first side (16) forming a plurality of stator teeth (26), the slots (20) defining a tooth pitch between each pair of adjacent stator teeth (26), and the second side (18) forming an annular stator yoke (28) connecting the stator teeth (26).

Description

Technical Field

[0001] The proposed technology relates generally to the field of axial flux motors and generators, and in particular to axial flux stators. background

[0002] An axial flux motor or axial gap motor is an electric motor having an architecture in which the magnetic flux between the rotor and stator is aligned parallel to the axis of rotation.

[0003] One type of axial flux stator has an annular stator yoke with stator teeth extending axially relative to the stator yoke. The stator yoke and the stator teeth together form a stator core. A coil of an electrically insulated conductor (such as a wire or a flat copper strip) is wound around each stator tooth to form a magnetic field parallel to the axis of rotation. It is known to make such an axial flux stator core from a metal strip by forming a plurality of slots on one side of the metal strip and winding the metal strip to form a spiral laminar structure. The side without the slots forms the annular stator yoke, and the side with the slots forms the stator teeth. The slots define the tooth spacing between the stator teeth. The slots have a fixed shape, which means that the tooth spacing does not depend on the radius. The innermost and outermost layers of the spiral laminar structure have the same tooth spacing as the remaining layers. By extension, this means that the stator teeth have a radial profile with sharp corners at the innermost and outermost layers.

[0004] An axial flux motor is typically shorter and wider than an equivalent radial flux motor. In some applications, such as when mounted coaxially on a drive shaft or transaxle in an automobile, having a narrower width is advantageous. The diameter of the stator generally sets the width of an axial flux motor. Furthermore, in an axial flux stator having a core with a helical laminar structure, the coils on the stator teeth protrude radially outward from the stator yoke and stator teeth, thus contributing to the diameter of the stator. Overview

[0005] An object of the proposed technology is to provide greater flexibility in forming coils on stator teeth of an axial flux stator. Another object of the proposed technology is to reduce the width of an axial flux stator having a helical laminar structure.

[0006] In a first aspect of the proposed technology, a method for manufacturing an axial flux stator core from a metal strip or an elongated metal sheet having a longitudinal first side and a longitudinal second side is proposed. The method includes: forming a plurality of slots in the first side of the metal strip, wherein each slot has a slot width, and the slot width varies or changes along the metal strip or the first side. The method also includes: winding or rolling the metal strip to form a helical layered or laminated structure, wherein the first side forms a plurality of stator teeth, the slots define the tooth spacing or tooth gap between each pair of adjacent stator teeth, and the metal strip forms an annular stator yoke connecting the stator teeth.

[0007] In a second aspect of the proposed technology, a system for manufacturing an axial flux stator core from a metal strip or an elongated metal sheet having a longitudinal first side and a longitudinal second side is proposed. The system includes: a stamping tool, the stamping tool is configured to form a plurality of slots in the first side of the metal strip, wherein each slot has a slot width, and the slot width varies or changes along the metal strip or the first side. The system also includes: a rolling tool or a winding roller, the rolling tool or the winding roller is configured to wind or roll the metal strip to form a spiral layered or laminated structure, wherein the first side forms a plurality of stator teeth, the slots define the tooth spacing or tooth gap between each pair of adjacent stator teeth, and the metal strip forms an annular stator yoke connecting the stator teeth.

[0008] In a third aspect of the proposed technology, an axial flux stator core is proposed, which has a spiral layered or laminated structure, wherein the axial flux stator core includes a metal strip or an elongated metal sheet having a longitudinal first side and a longitudinal second side and is wound to form a spiral layered structure. The first side of the metal strip has a plurality of slots, each slot having a slot width, and the slot width varies or changes along the metal strip or the first side. The first side forms a plurality of stator teeth, the slots define a tooth spacing or tooth gap between each pair of adjacent stator teeth, and the metal strip forms an annular stator yoke connecting the stator teeth.

[0009] In a fourth aspect of the proposed technology, a method for manufacturing an axial flux stator is proposed. The method may include any steps or features of the first aspect of the proposed technology. In addition, the method also includes: forming or winding a coil of an electrically insulated conductor on each stator tooth.

[0010] In a fifth aspect of the proposed technology, an axial flux stator is proposed, which includes an axial flux stator core according to the third aspect of the proposed technology. The axial flux stator also includes: a plurality of coils individually positioned on or wound around the stator teeth. In other words, the axial flux stator also includes: a plurality of coils, wherein each coil is individually positioned on or wound around one of the stator teeth. In other words, the axial flux stator also includes: a plurality of coils, wherein each stator tooth is equipped with one of the plurality of coils. It should be understood that each coil is positioned on or wound around the stator tooth to which it is equipped. It should be understood that the coil is an electromagnetic coil. It should also be understood that each coil may include an electrically insulated conductor.

[0011] For example, the axial flux stator core or axial flux stator can be used in an electric motor or generator. In a sixth aspect of the proposed technology, an axial flux motor or generator is proposed, which includes the axial flux stator core according to the third aspect of the proposed technology or the axial flux stator according to the fifth aspect of the proposed technology.

[0012] It will be appreciated that the slot width is aligned with the metal strip, or parallel to the first side of the metal strip. The varying slot width along the metal strip means that the tooth spacing varies relatively radially in the helical layered structure. This facilitates forming the coils on the stator teeth with greater flexibility and allows the radial profile of the stator teeth to be optimized. For example, the radial profile can be adapted to different types or sizes and shapes of insulated conductors forming the coils wound around the stator teeth.

[0013] The metal strip may be silicon steel or electrical steel.It will be appreciated that the formation of the plurality of slots and the winding of the metal strip are synchronized such that the slots overlap in the helical layered structure and form stator teeth at a first side of the metal strip.

[0014] It will be appreciated that the axial flux stator core defines an axial direction, a radial direction and a tangential direction relative to the axis of rotation during use, for example in an electric motor or generator. Similarly, the helical layered structure defines an axial direction, a radial direction and a tangential direction relative to the axis of rotation during winding of the metal strip. The axis of rotation during use and during winding may be the same, meaning that the mentioned directions coincide. For example, the axial direction is the same both during use and during winding.

[0015] The longitudinal side is understood here to extend longitudinally relative to the strip. It is provided that the slot has a slot width that varies or changes along the metal strip. It is understood that the longitudinal first side and the longitudinal second side may be parallel. It is provided that the slot width varies along the metal strip. In other words, consecutive slots may have different slot widths. It is understood that each tooth extends radially, tangentially and axially relative to the spiral laminar structure. It is also understood that each slot extends tangentially and axially. It is also understood that the tooth spacing is aligned tangentially to the spiral laminar structure.

[0016] Each slot may define a first slot edge and a second slot edge on the metal strip, wherein the first slot edge and the second slot edge are spaced apart and connected to or extend from the first side of the metal strip. It should be understood that the spacing of the first slot edge and the second slot edge defines the slot width. Each slot may also define a third slot edge, wherein the third slot edge is spaced apart from the first side of the metal strip and interconnected with the first slot edge and the second slot edge. The first slot edge and the second slot edge may be straight or linear. The first slot edge and the second slot edge may be parallel. This means that each slot has a constant slot width from the third slot edge to the first side of the metal strip. The first slot edge and the second slot edge may be transverse or perpendicular to the first side of the metal strip. It should be understood that the third slot edge may be straight or linear, and the third slot edge may be perpendicular to the first slot edge and the second slot edge, or aligned or parallel to the first edge of the metal strip. In other words, the slot width of each slot may be constant or unchanging, transverse to the metal strip or perpendicular to the first side of the metal strip. In other words, each slot may outline a rectangle that opens at the first side of the metal strip. The constant width of the slot allows it to be formed from two or more notches using the same mating punch and die. It also allows a pre-wound coil to be pushed onto a stator tooth. In extension, this allows the use of flat conductors in the coil, where either the wide or narrow side of the conductor faces the stator tooth.

[0017] It should be understood that in an axial flux stator, each coil may conform to the stator tooth on which it is formed or positioned. It is provided above that in a fourth aspect of the proposed technology, the method comprises: forming a coil of an electrically insulated conductor on each stator tooth. It should be understood that this includes forming a plurality of coils separate from the stator core and mounting one of the plurality of coils on each stator tooth, or pushing one of the plurality of coils onto each stator tooth. It is provided above that in a fifth aspect of the proposed technology, the coils are individually positioned on the stator teeth. In other words, each stator tooth is equipped with one of the plurality of coils. It is also provided that each coil may comprise an electrically insulated conductor. Each coil may be a prefabricated coil. This means that the coil has been formed or wound separately from the stator core.

[0018] For example, the conductor of each coil can be a flat conductor strip having a first wide side and a first narrow side. The first wide side can be arranged to face the stator teeth on which the coil is wound or mounted. This means that the first wide side constitutes the inner side of the conductor or coil. In other words, the coil can be a radially extended multi-layer flat conductor coil. Alternatively, the first narrow side can be arranged to face the stator teeth on which the coil is wound or mounted. This means that the first narrow side constitutes the inner surface of the conductor or coil. In other words, the coil can be an axially extended single-layer flat conductor coil. It should be understood that the conductor can have a second wide side facing the opposite direction relative to the first wide side, and the first narrow side can be interconnected with the first wide side and the second wide side. It should also be understood that the conductor can have a second narrow side facing the opposite direction relative to the first narrow side, and the second narrow side can be interconnected with the first wide side and the second wide side. In both examples, it should be understood that the coil is arranged so that the first wide side is juxtaposed with or contacts the second wide side within the coil.

[0019] The spiral layered structure can have a plurality of spiral or radially arranged layers. It should be understood that these layers contact each other to form a radial sandwich structure. It should also be understood that the spiral layered structure comprises a radially outermost layer and a radially innermost layer. The layers or each layer of the spiral layered structure can have the same groove width.

[0020] The spirally arranged structure may have a radially inner half and a radially outer half that together form the spirally arranged structure. It should be understood that the inner half and the outer half are connected at the middle between the innermost layer and the outermost layer. It should also be understood that the innermost layer forms a part of the inner half, and the outermost layer forms a part of the outer half. It should also be understood that the innermost layer and the outermost layer are respectively composed of multiple layers. The groove width of the groove in the radially outermost layer may be greater than the groove width of the groove in the other layers of the outer half. The groove width of the groove in the radially innermost layer may be greater than the groove width of the groove in the other layers of the inner half.

[0021] The groove width of the groove in the outermost layer can be greater than the groove width in the adjacent second outermost layer. Similarly, the groove width of the groove in the second outermost layer can be greater than the groove width in the adjacent third outermost layer. Similarly, the groove width of the groove in the third outermost layer can be greater than the groove width in the adjacent fourth outermost layer. The groove width in the innermost layer can be equal to or greater than the groove width in the adjacent second innermost layer. The groove width can be the same in and between the majority or more than 60%, 70% or 80% of the spirally arranged layers.

[0022] As described above, adjacent stator teeth define a tooth spacing or tooth gap between them. The tooth spacing may vary depending on the radius or vary between layers. The tooth spacing in the outermost layer may be greater than the tooth spacing in the adjacent inner layer. The tooth spacing in the innermost layer may be greater than the tooth spacing in the adjacent outer layer. In other words, each stator tooth may have a tooth width. It should be understood that the tooth width is tangent to the spiral layered structure. The tooth width may vary depending on the radius or vary between layers. The tooth width at the outermost layer may be less than the tooth width at the adjacent inner layer. The tooth width at the innermost layer may be less than the tooth width at the adjacent outer layer. The features described herein contribute to a radial profile or radial cross-section of a stator tooth with rounded corners. The rounded corners allow the coil to be wound more tightly around the teeth, reducing the radial protrusion of the coil relative to the teeth.

[0023] The plurality of slots may include: a first subset of slots and a second subset of slots. The slots in the first subset may have equal slot widths, and the slots in the second subset may have equal slot widths. One or more slot widths of the second subset are greater than one or more slot widths of the first subset. The proposed system may further include: a controller or control unit connected to a punching tool and a rolling tool. It should be understood that the controller is arranged to control the functions of the punching tool and the rolling tool. The controller may be configured to synchronize the punching tool and the rolling tool so that the slots overlap in the spiral laminar structure and form stator teeth at the first side of the metal strip. The controller may be configured to operate the punching tool and the rolling tool to change the slot width along the metal strip or along the first side. The controller may be configured to operate the punching tool and the rolling tool to form the first subset of slots and the second subset of slots.

[0024] In the proposed method, winding the metal strip may include positioning a first subset of slots in a first layer of a spiral laminar structure, and positioning a second subset of slots in a second layer of the spiral laminar structure. In the proposed system, a controller may be configured to operate a punching tool and a rolling tool for positioning the first subset of slots in the first layer of the spiral laminar structure, and for positioning the second subset of slots in the second layer of the spiral laminar structure. In the proposed axial flux stator core, the first subset of slots may be positioned in the first layer of the spiral laminar structure, and the second subset of slots may be positioned in the second layer of the spiral laminar structure.

[0025] The second layer may be positioned radially outward of the first layer. For example, the second layer may be the outermost layer, and the first layer may be positioned between the innermost layer and the outermost layer. Alternatively, the second layer may be the innermost layer, and the first layer may be positioned between the innermost layer and the outermost layer. The first layer and the second layer may be juxtaposed.

[0026] In the proposed method and axial flux stator core, a plurality of slots may be formed by notching a first side of a metal strip by a mating punch and die. The stamping tool in the proposed system may include a mating punch and die configured to notch and form a plurality of slots on a first side of a metal strip. It should be understood that a single notch forms a slot having a fixed size or a fixed slot width. In other words, the notch has a notch width along or parallel to the first side of the metal strip.

[0027] Each slot of the first subset may be formed by a single notch. The controller may be configured to operate the punching tool and the rolling tool to form each slot of the first subset by a single notch. Each slot of the second subset may be formed by a first notch, a displacement of the metal strip relative to the punch and the die, and a second notch overlapping the first notch. The controller may be configured to operate the punching tool and the rolling tool to form each slot of the second subset by a first notch, a displacement of the metal strip relative to the punch and the die, and a second notch overlapping the first notch.

[0028] In other words, each groove in the first subset can be formed by notching a first number of times, and each groove in the second subset can be formed by notching a second number of times, the second number being greater than the first number. The controller can be configured to operate the punching tool and the rolling tool for forming each groove in the first subset by notching a first number of times, and for forming each groove in the second subset by notching a second number of times, the second number being greater than the first number. The notches forming the grooves can overlap. It should be understood that this requires that the number of notches is greater than one. For example, each groove in the first subset can be formed by a single notch, and each groove in the second subset can be formed by two overlapping notches, or each groove in the first subset can be formed by two overlapping notches, and each groove in the second subset can be formed by three overlapping notches.

[0029] More generally, the plurality of slots may include: a subset of slots, wherein each slot in the subset is formed by two or more overlapping notches. The controller may be configured to operate a punching tool and a rolling tool to form a subset of slots, wherein each slot in the subset is formed by two or more overlapping notches. It is provided above that the plurality of slots may be formed by notching a first side of a metal strip by a mating punch and die. It should be understood that the overlapping notches forming the slots have different positions along the metal strip or parallel to the first side of the metal strip. In other words, when forming the slots of the subset of slots, the metal strip may be displaced between the notches relative to the punch and the die, or the controller may be configured to operate a punching tool and a rolling tool to displace the metal strip between the notches relative to the punch and the die.

[0030] It will be appreciated that each notch has a notch width along the metal strip or parallel to the first side of the metal strip. Thus, the overlapping notches form a groove having a groove width greater than the notch width of a single notch. It will be appreciated that the subset comprises at least two grooves. The number of notches forming the grooves of the subset may vary along the metal strip, or between the grooves of the subset of grooves. Additionally or alternatively, the overlap of the notches forming the grooves of the subset may vary along the metal strip or between the grooves, or the relative position between the notches forming the grooves of the subset may vary along the metal strip or between the grooves. In other words, the displacement between the notches described above may vary along the metal strip or between the grooves of the subset of grooves.

[0031] For example, a first slot of a subset may be formed by a first number of overlapping notches. A second slot of a subset may be formed by a second number of overlapping notches. It should be understood that the first number and the second number are greater than one. The first number and the second number may be the same, and the relative positions between the notches of the second number may be different from the relative positions between the notches of the first number. Additionally or alternatively, the second number may be different from the first number. It should be understood that the plurality of slots may also include: additional subsets of slots, wherein each slot in the additional subsets is formed by a single notch or by two or more overlapping notches. It should also be understood that the controller may be configured to operate a punching tool and a rolling tool to form an additional subset of slots, wherein each slot in the additional subsets is formed by a single notch or by two or more overlapping notches.

[0032] The proposed method may further include: forming one or more welds connecting adjacent layers of the spiral layered structure. The proposed system may further include: a welding portion configured to form one or more welds connecting adjacent layers of the spiral layered structure. The proposed axial flux stator core may include one or more welds connecting adjacent layers of the spiral layered structure. The weld may prevent the spiral layered structure from unfolding. The weld may extend radially relative to the spiral layered structure. Each weld may extend over all layers of the spiral layered structure. The weld may be positioned on the second side or the stator yoke.

[0033] It is provided that the metal strip forms an annular stator yoke connecting the stator teeth. In addition, the second side of the metal strip can form an annular stator yoke. This means that the second side does not form a plurality of additional stator teeth.

[0034] Alternatively, the method according to the first aspect of the proposed technology may further include: forming a plurality of additional slots in the second side of the metal strip, wherein each second slot has a slot width, and the slot width varies or changes along the metal strip or the second side. In the second aspect of the proposed technology, the stamping tool may also be configured to form a plurality of additional slots in the second side of the metal strip, wherein each additional slot has a slot width, and the slot width varies or changes along the metal strip or the second side. In the third aspect of the proposed technology, the second side of the metal strip may have a plurality of additional slots, each additional slot having a slot width, and the slot width varies or changes along the metal strip or the second side. In the fourth aspect of the proposed technology, the method may further include: forming or winding a coil of an electrically insulated conductor on each additional stator tooth. In the fifth aspect of the proposed technology, the axial flux stator may further include: a plurality of coils individually positioned on or wound around the additional stator teeth. In other words, each coil may be individually positioned on or wound around one of the stator teeth or the additional stator teeth. In the spiral laminar structure, the second side may form a plurality of additional stator teeth, the additional slots defining a tooth spacing or tooth gap between each pair of adjacent additional stator teeth, and an annular stator yoke connecting the additional stator teeth. The annular stator yoke may be positioned between the stator teeth and the additional stator teeth. The additional slots may have the same features as the slots or be arranged in the same manner as the slots. Similarly, the additional stator teeth may have the same features as the stator teeth or be arranged in the same manner as the stator teeth. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and other features and advantages of the proposed technology will be more fully understood from the following detailed description of preferred embodiments of the proposed technology taken in conjunction with the accompanying drawings, in which: Figure 1 is a schematic diagram of a system for manufacturing an axial flux stator core, Figure 2 is using Figure 1 A perspective view of an axial flux stator core during system fabrication. Figure 3a to Figure 3c It is shown Figure 2 Planar projection of the final geometry of the axial flux stator core, Figure 4a It is shown Figure 2 The axial magnetic flux is the plane projection of the position of the coil on one of the stator teeth of the stator core, Figure 4b It is shown Figure 2 The axial flux of the stator core is a planar projection of the position of the alternative coil on one of the stator teeth of the stator core, and Figure 5 is a perspective view of an axial flux stator core with additional stator teeth. Detailed description of the drawings

[0036] exist Figure 1 Schematically shown in FIG. 1 is a system 10 for manufacturing an axial flux stator core 50. The system 10 has a stamping tool 12, and a metal strip 14 made of silicon steel is fed into the stamping tool 12. The metal strip 14 has a longitudinal first side 16 and a longitudinal second side 18. The stamping tool 12 has a matching punch 32 and die 34, which notches the first side 16 of the metal strip 14 and forms a plurality of slots 20 on the first side 16.

[0037] The system 10 also has a rolling tool 22 having a roller 58 operatively connected to an electric motor 54 via a belt 56. After the metal strip 14 passes through the punching tool 12, the rolling tool 22 winds the metal strip 14 onto the roller 58. In this way, a spiral layered structure 24 having a plurality of mutually contacting spirally arranged and sandwiched layers 36 is formed.

[0038] The system 10 has a controller 30 that is connected to and synchronizes the punching tool 12 and the rolling tool 22 so that the slots 20 overlap in the spiral layered structure 24. In this way, the first side 16 of the metal strip 14 forms a plurality of stator teeth 26, and the slots 20 define the tooth spacing between adjacent pairs of stator teeth 26. The second side 18 of the metal strip 14 forms an annular stator yoke 26 connecting the stator teeth 26.

[0039] The controller 30 operates the punching tool 12 and the rolling tool 22 so that several subsets of the grooves 20 are formed. An initial subset is formed in which the grooves 20 are positioned in the innermost layer 38 of the spiral layered structure 24. Each groove 20 in the initial subset is formed by the controller 30 operating the punching tool 12 and the rolling tool 22 to form the groove by punching a first notch, displacing the metal strip 14 relative to the punch 32 and the die 34, and punching a second notch overlapping the first notch. In this way, a groove width wider than a single notch is achieved. The displacement of the metal strip 14 decreases sequentially, which means that the groove width changes along the metal strip 14 in the innermost layer 38. A second subset is formed in which the grooves 20 are positioned between the innermost layer 38 and the third outermost layer 40. The controller 30 operates the punching tool 12 and the rolling tool 22 to form each slot 20 by a single notch formed by the punching tool 12, which means that the slots 20 of the second subset have the same slot width, and the slot width in the second subset is narrower than the slot width in the initial subset. A third subset is formed, in which the slots 20 are positioned in the third outermost layer 40. Each slot 20 in the third subset is formed by the controller 30 operating the punching tool 12 and the rolling tool 22 to form the slot 20 by punching a first notch, displacing the metal strip 14 relative to the punch 32 and the die 34, and punching a second notch overlapping the first notch. In this way, a wider slot width is achieved compared to the second subset. For all slots 20 of the third subset, the displacement of the metal strip is the same, which means that they have the same slot width. A fourth subset is formed, in which the slots 20 are positioned in the second outermost layer 42. The fourth subset of slots 20 is formed in the same manner as the third subset of slots 20, but the larger displacement of the metal strip 14 between the first notch and the second notch results in a larger slot width. A final subset is formed in which the slots 20 are positioned in the outermost layer 44. The final subset of slots 20 is formed in the same manner as the fourth subset of slots 20, but the larger displacement of the metal strip 14 between the first notch and the second notch results in an even larger slot width. The slot width of the slot 20 is determined by Figure 2 Indicated by the double-headed arrow 52 in FIG.

[0040] It should be noted that the numbering of the layers and subsets corresponds to the radial position in the spiral layered structure 24, and different numbering may be used regardless of the radial position. For example, the fourth outermost layer may be considered as the first layer, the grooves 20 in the fourth outermost layer may be considered as the first subset, the third outermost layer 40 may be considered as the second layer, and the grooves 20 in the third outermost layer 40 may be considered as the second subset. This means that the grooves 20 in the first subset have an equal groove width formed by a single notch, and the grooves in the second subset have an equal groove width formed by two notches, and the groove width of the second subset is greater than the groove width or width of the first subset.

[0041] Each slot 20 defines a first slot edge 62, a second slot edge 64, and a third slot edge 66 on the metal strip 14. The first slot edge 62 and the second slot edge 64 are spaced apart and connected to the first side 16 of the metal strip 14, thereby defining the slot width 52. The third slot edge 66 is spaced apart from the first side 16 and interconnects the first slot edge 62 and the second slot edge 64. The first slot edge 62 and the second slot edge 64 are straight and parallel. The first slot edge 62 and the second slot edge 64 are also perpendicular to the first side 16 of the metal strip 14. The third slot edge 66 is parallel to the first edge 16 of the metal strip 14. In this way, each slot 20 outlines a rectangle in which the slot width 52 is constant in the transverse direction of the strip 14.

[0042] The resulting spiral layered structure 24 has an outermost layer 44, the slot width of which is greater than the slot width in the adjacent inner layer 42. The slot width in the innermost layer 38 is equal to and greater than the slot width in the adjacent outer layer. This means that the tooth spacing varies according to the radius. Each stator tooth 26 has a tooth width that is tangentially aligned with the spiral layered structure 24, and the tooth width varies according to the radius. The tooth width at the outermost layer 44 is less than the tooth width at the adjacent inner layer 42, and the tooth width at the innermost layer 38 is less than the tooth width at the adjacent outer layer. The radial profile of the stator tooth 26 has rounded corners, which can be Figure 3a 4 , this allows the coils 46 to be more tightly wound and protrude less radially relative to the stator teeth 26 .

[0043] In alternative embodiments, the number of notches may be different and the overlap between notches may be different. For example, the notch width of the punch tool 12 may be half that of the previous example. Each slot 20 of the initial subset is formed by three overlapping notches with uniform displacement between the notches. Each slot 20 of the second subset is also formed by three overlapping notches, but has a shorter displacement compared to the initial subset. Each slot 20 of the third subset is formed by three overlapping notches with a displacement similar to that of the initial subset. Each slot 20 of the fourth subset is formed by three overlapping notches with a longer displacement between the notches compared to the initial subset. Each slot 20 of the final subset is formed by four overlapping notches with uniform displacement between the notches.

[0044] See also Figure 3c The system 10 also has a weld (not shown) that forms four radially extending welds 48 on the stator yoke 28 that join adjacent layers of the spiral layered structure 24 and prevent it from unfolding once removed from the rolling tool.

[0045] like Figure 3aAs shown, the spirally arranged structure 24 has a radially inner half 58 and a radially outer half 60, which are connected at the middle (dashed line) between the innermost layer 38 and the outermost layer 44. The groove width 52 of the groove 20 in the radially outermost layer 44 is greater than the groove width 52 of the groove 20 in the other layers of the outer half 60, which can be Figure 2 Similarly, the groove width 52 of the grooves 20 in the radially innermost layer 38 is greater than the groove width 52 of the grooves 20 in the other layers of the inner half 58.

[0046] As shown above, the system 10 implements a method of manufacturing an axial flux stator core 50 from a metal strip 14 having a longitudinal first side 16 and a longitudinal second side 18. In summary, slots are formed in the first side 16 of the metal strip, and the slot width varies along the metal strip 14. The metal strip 14 is rolled to form a helical layered structure 24, wherein the first side forms a plurality of stator teeth 26, and the second side forms an annular stator yoke 28 connecting the stator teeth 26.

[0047] The resulting axial flux stator core 50 has a helical layered structure 24 formed from a rolled metal strip 14 having a longitudinal first side 16 and a longitudinal second side 18. The overall geometry of the stator core 50 is Figure 3a to Figure 3c The first side 16 of the metal strip 14 has a plurality of slots 20, the width of which varies along the metal strip 14. The first side 16 forms a plurality of stator teeth 26, and the second side 18 forms an annular stator yoke 28 connecting the stator teeth 26.

[0048] like Figure 4a As shown, to make an axial flux stator (not shown), a coil 46 of electrically insulated conductor 76 is wound around each stator tooth 26. The axial flux stator (not shown) can be installed in an axial flux motor or generator (not shown). Each conductor 76 is a coated flat copper strip having a first wide side 68 and an opposite second wide side 70. They are interconnected by a first narrow side (not shown) and a second narrow side (not shown) facing opposite directions (perpendicular to the plane of the sheet) and perpendicular to the first wide side 68 and the second wide side 70. The first wide side 68 is arranged to face the inner side of the stator tooth 26. In this way, the coil 46 constitutes a radially expanded multi-layer flat conductor coil. Figure 4bAn alternative embodiment is shown in , in which each conductor 76 is a coated flat copper strip, but is wound in a different manner. The coils 46 are prefabricated separately from the axial flux stator core 50, and the coils 46 are installed by pushing the coils 46 onto the stator teeth 26. In each coil 46, the first narrow side 72 of the flat copper strip is arranged to face the stator teeth 26, and the second narrow side 74 is arranged to face away from the stator teeth 26. The first wide side 68 and the opposite second wide side (not shown) face in opposite directions (perpendicular to the plane of the sheet) and are connected by the first narrow side 72 and the second narrow side 74. This means that the first narrow side 72 constitutes the inner surface of the conductor 76. In this way, the coil 46 is an axially expanded single-layer flat conductor coil.

[0049] exist Figure 5 An alternative embodiment of a helical layered structure 24 for an axial flux stator core 50 is shown in FIG. The structure 24 has Figure 2 In addition, the structure 24 also has a plurality of additional teeth 56 formed by additional grooves 54 in the second side 18 of the metal strip 14. The spiral layered structure 24 is similar to the structure described above. Figure 1 The system 10 described is manufactured. The system 10 has an additional punching tool (not shown) having an additional mating punch (not shown) and a die (not shown) that notches the second side 18 of the metal strip 14 and forms a plurality of additional slots 54 in the second side 18. The slots on the first side 16 and the additional slots 54 on the second side 18 are arranged in pairs. The controller 30 of the system is connected to the additional punching tool (not shown) and controls the additional punching tool (not shown) so that in each pair, the additional slots 54 are located just opposite the slots 20 and have the same slot width 52 as the slots 20. The controller 30 operates the additional punching tool (not shown) in the same manner as the punching tool 12. For example, by punching two overlapping notches with the rolling tool 22, the displacement of the metal strip 14 between the notches is changed, thereby achieving a varying slot width 52. When the rolling tool 22 forms the spiral layered structure 24, the additional slots 54 overlap in the same manner as the slots 20, and additional teeth 56 are formed at the second side 18.

[0050] Project List 10 System 12 Punching tools 14 Metal Strip 16 First side of metal strip 18 Second side of metal strip 20 slots 22 Scroll Tool 24 Helical layered structure 26 stator teeth 28 Stator yoke 30 Controller 32 Punch 34 Die 36 floors 38 Innermost layer 40 third outermost layer 42 second outermost layer 44 Outermost layer 46 Coil 48 Weld 50 Axial Flux Stator Core 52 Slot Width 54 additional slots 56 Additional teeth 58 Radially inner half of the spiral layer structure 60 Radially outer half of the spiral layer structure 62 First groove edge 64 Second slot edge 66 Third groove edge 68 First wide side 70 Second wide side 72 First narrow side 74 Second narrow side 76 Conductors.

Claims

1. A method for manufacturing an axial flux stator core (50) from a metal strip (14), the metal strip (14) having a longitudinal first side (16) and a longitudinal second side (18), wherein the method comprises: A plurality of grooves (20) are formed in the first side (16) of the metal strip (14), wherein each groove (20) has a groove width, and wherein the groove width (52) varies along the metal strip (14), and The metal strip (14) is wound to form a helical layered structure (24), wherein the first side (16) forms a plurality of stator teeth (26), the slots (20) define a tooth spacing between each pair of adjacent stator teeth (26), and the metal strip (14) forms an annular stator yoke (28) connecting the stator teeth (26).

2. The method according to claim 1, wherein: Each slot (20) defines a first slot edge (62) and a second slot edge (64) on the metal strip (14), the first slot edge (62) and the second slot edge (64) being spaced apart and connected to the first side (16) of the metal strip (14), and the first slot edge (62) and the second slot edge (64) being straight.

3. The method according to claim 1 or 2, wherein: The spiral layered structure (24) has a plurality of spirally arranged layers (36), the plurality of spirally arranged layers (36) including a radially outermost layer (44) and a radially innermost layer (38), and the groove width of the groove (20) in the outermost layer (44) is greater than the groove width in the adjacent second outermost layer (42).

4. The method according to claim 3, wherein: The groove width of the groove (20) in the second outermost layer (42) is greater than the groove width in the adjacent third outermost layer (40).

5. The method according to any one of claims 1 to 4, wherein: The plurality of grooves (20) comprises a subset of grooves (20), wherein each groove (20) in the subset is formed by two or more overlapping notches.

6. The method according to any one of claims 1 to 4, wherein: The plurality of grooves (20) include a first subset of grooves (20) and a second subset of grooves (20), the grooves (20) in the first subset having equal groove widths (52), and the grooves (20) in the second subset having equal groove widths (52), and the groove widths of the second subset are greater than the groove widths of the first subset.

7. The method according to claim 6, wherein: The plurality of slots (20) are formed by cooperating punches (32) and dies (34) that notch the first side (16) of the metal strip (14), each slot (20) of the first subset being formed by a single notch, and each slot (20) of the second subset being formed by a first notch, a displacement of the metal strip (14) relative to the punch (32) and the die (34), and a second notch overlapping the first notch.

8. An axial flux stator core (50), the axial flux stator core (50) having a spiral layered structure (24), wherein: The axial flux stator core (50) comprises a metal strip (14) having a longitudinal first side (16) and a longitudinal second side (18) and the metal strip (14) is wound to form the helical layered structure (24), the first side (16) of the metal strip (14) having a plurality of slots (20), wherein each slot (20) has a slot width and the slot width (52) varies along the metal strip (14), the first side (16) forming a plurality of stator teeth (26), the slots (20) defining a tooth spacing between each pair of adjacent stator teeth (26), and the second side (18) forming an annular stator yoke (28) connecting the stator teeth (26).

9. The axial flux stator core (50) according to claim 8, wherein: Each slot (20) defines a first slot edge (62) and a second slot edge (64) on the metal strip (14), the first slot edge (62) and the second slot edge (64) being spaced apart and connected to the first side (16) of the metal strip (14), and the first slot edge (62) and the second slot edge (64) being straight.

10. The axial flux stator core (50) according to claim 8, wherein: The spiral layered structure (24) has a plurality of spirally arranged layers (36), the groove width of the groove (20) in the outermost layer (44) is greater than the groove width in the adjacent second outermost layer (42), the groove width of the groove (20) in the second outermost layer (42) is greater than the groove width in the adjacent third outermost layer (40), and the groove width (52) is the same in and between most of the spirally arranged layers (36).

11. The axial flux stator core (50) according to any one of claims 8 to 10, wherein: The plurality of grooves (20) include a first subset of grooves (20) and a second subset of grooves (20), and the grooves (20) in the first subset have equal groove widths (52), and the grooves (20) in the second subset have equal groove widths (52), the grooves (20) of the first subset are positioned in a first layer of the spiral layered structure (24), the grooves (20) of the second subset are positioned in a second layer of the spiral layered structure (24), the groove width of the second subset is greater than the groove width of the first subset, and the second layer is positioned radially outside the first layer.

12. A system (10) for manufacturing an axial flux stator core (50) from a metal strip (14), the metal strip (14) having a longitudinal first side (16) and a longitudinal second side (18), wherein the system (10) comprises: a stamping tool (12) configured to form a plurality of slots (20) in the first side (16) of the metal strip (14), wherein each slot (20) has a slot width, and wherein the slot width (52) varies along the metal strip (14), and A rolling tool (22) is configured to wind the metal strip (14) to form a spiral layered structure (24), wherein the first side (16) forms a plurality of stator teeth (26), the slots (20) define a tooth spacing between each pair of adjacent stator teeth (26), and the second side (18) forms an annular stator yoke (28) connecting the stator teeth (26).

13. A method for manufacturing an axial flux stator, wherein: The method comprises the method according to any one of claims 1 to 7, and the method further comprises: A coil (46) of electrically insulated conductor is formed on each of the stator teeth (26).

14. An axial flux stator, comprising the axial flux stator core (50) according to any one of claims 8 to 11, wherein: The axial flux stator also includes a plurality of coils (46) individually positioned on the stator teeth (26).

15. An axial flux motor or generator comprising an axial flux stator according to claim 14.

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