Stator, motor, and production method for stator

Abstract

A stator according to the present invention includes: a stator core that has an annular core back part that is centered on an axis, a plurality of tooth parts that are arranged in the circumferential direction on one surface of the core back part so as to protrude in the axial direction, and a plurality of slots that are arranged in the circumferential direction between tooth parts that are adjacent in the circumferential direction; and a coil that is positioned in the plurality of slots. The stator core includes steel sheets that are stacked in the radial direction. The core back part has a plurality of grooves that are recessed in the axial direction and extend from the inside in the radial direction to the outside in the radial direction of the core back part. When the stator core is viewed in the axial direction, center lines of the slots and center lines of the grooves are parallel.

Description

Stator, motor, and method for manufacturing a stator

[0001] The present invention relates to a stator, a motor, and a method for manufacturing a stator. This application claims priority based on Japanese Patent Application No. 2025-014449 filed on January 31, 2025, and the contents thereof are incorporated herein by reference.

[0002] Axial-gap motors in which magnetic flux is formed in the axial direction of the motor are known. For example, Patent Documents 1 and 2 disclose stators that form part of an axial-gap motor.

[0003] The stator of Patent Document 1 has an annular portion and a plurality of columnar teeth portions that are arranged in the circumferential direction of the annular portion and project to one side in the axial direction of the annular portion.

[0004] The stator of Patent Document 2 has a stator core having an annular core back portion and a core portion extending axially from the core back portion.

[0005] The stator core of an axial-gap motor is manufactured, for example, by laminating steel sheets in the radial direction. For example, the method for manufacturing the stator core of Patent Document 1 is as follows.

[0006] First, a plurality of core sheets having a long portion extending in the longitudinal direction and a plurality of convex portions arranged in the longitudinal direction of the long portion and projecting to one side in the lateral width direction of the long portion are formed by punching or the like.

[0007] Next, the formed plurality of core sheets are bent and laminated in the radial direction to assemble a stator core. In the stator of Patent Document 1, the annular portion is formed by laminating the long portions, and the convex portions are laminated to form a plurality of teeth.

[0008] Note that the stator of Patent Document 2 is also manufactured by a manufacturing method generally similar to the above-described manufacturing method.

[0009] In the axial gap type motor described above, the width of the teeth is greater radially outward than radially inward. Therefore, in the manufacturing method of the stator core of the axial gap type motor described above, the pitch of the protrusions on the core sheet is larger towards the radially outward direction.

[0010] Japanese Patent Publication No. 2018-129946 Japanese Patent Publication No. 2019-165519

[0011] Incidentally, there is a desire to reduce the weight of axial gap motors. For example, one could consider reducing the weight of the stator core. As mentioned above, in the manufacturing method of the stator core, the pitch of the slots between the protrusions in the steel plate constituting the stator core increases as it moves radially outward from the stator core. If, in order to reduce the weight of the stator core, not only the slots but also the other parts of the steel plate are punched out, it is necessary to adjust the pitch between the slots and the parts of the weight reduction according to the radial position of the stator core. Therefore, if an attempt is made to reduce the weight of the motor by processing the steel plate, such as punching out the parts of the weight reduction, the processing of the steel plate becomes complicated due to the pitch adjustment described above, which may reduce production efficiency.

[0012] The objective of the present invention is to provide a stator for an axial gap type motor that can be made lighter and improve production efficiency.

[0013] An exemplary embodiment of the present invention provides a stator having a stator core. The stator core has radially laminated steel plates. The core back portion has a plurality of grooves that are recessed in the axial direction and extend from the radially inner to the radially outer side of the core back portion. The center lines of the slots and the center lines of the grooves are parallel when the stator core is viewed in the axial direction.

[0014] A method for manufacturing a stator according to an exemplary embodiment of the present invention comprises a punching step of punching out a plurality of slots and core back portions into a steel sheet, and punching out a plurality of groove portions into the core back portion, and a stator core forming step of stacking the steel sheets punched out in the punching step in the thickness direction to form a stator core in the radial direction. In the punching step, each of the plurality of slots and each of the plurality of groove portions are punched out into the steel sheet in the same positional relationship.

[0015] According to the present invention, it is possible to provide a configuration for the stator of an axial gap type motor that can be made lighter and improve production efficiency.

[0016] Figure 1 is a cross-sectional view showing an example of the schematic configuration of a motor. Figure 2 is an exploded perspective view showing an example of the schematic configuration of a stator. Figure 3 is a diagram illustrating the center lines of the slots and grooves in the stator. Figure 4 is a diagram illustrating the center lines of the slots and grooves in the stator core of a conventional stator. Figure 5 is a diagram showing the formation process of the strip-shaped steel plate constituting the stator core of a conventional stator. Figure 6 is a diagram showing the punching process in the manufacturing method of a stator. Figure 7 is a diagram showing the stator core formation process in the manufacturing method of a stator. Figure 8 is a diagram illustrating the method of forming the tooth chamfer and groove chamfer. Figure 9 is a schematic side view showing a part of the stator core.

[0017] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. Note that identical or corresponding parts in the drawings are denoted by the same reference numerals, and their descriptions will not be repeated. Furthermore, the dimensions of the components in each drawing do not faithfully represent the actual dimensions of the components or their dimensional ratios.

[0018] In the following description, the direction in which the central axis P of the motor 100, rotor 50, and stator 1 extends is referred to as "axial direction A". The circumferential direction centered on the central axis P is referred to as "circumferential direction C", and the radial direction centered on the central axis P is referred to as "radial direction B". Furthermore, the direction described as "radial outward" in the specification is shown as "B1" in the figures, and the direction described as "radial inward" is shown as "B2" in the figures. Note that the directions shown in the figures are defined solely for the convenience of explanation and do not limit the orientation of the motor during use or assembly according to the present invention.

[0019] Furthermore, in the following explanation, the expressions "fix," "connect," and "attach" (hereinafter referred to as "fixing, etc.") include not only cases where components are directly fixed to each other, but also cases where they are fixed to each other via other components. In other words, in the following explanation, the expressions "fixing, etc." include both direct and indirect fixing of components to each other.

[0020] (Motor) Figure 1 is a cross-sectional view showing an example of the schematic configuration of the motor 100. Referring to Figure 1, the motor 100 is, for example, an axial gap type motor in which the magnetic flux is formed in a direction parallel to the central axis P. The motor 100 has a rotor 50 and stators 1 located on both sides of the axial direction A of the rotor 50. Thus, the motor 100 is a DSSR (Double Stator Single Rotor) type motor. The stator cores 10 of the stators 1 located on both sides of the axial direction A of the rotor 50 have the same shape as the stators 1, except that their orientation in the axial direction A is opposite. For this reason, one of the stators 1 will be described below.

[0021] (Stator) Figure 2 is an exploded perspective view showing an example of the schematic configuration of the stator 1. Figure 3 is a diagram illustrating the positional relationship between the center line CL1 of the slot SL1 and the center line CL2 of the groove 111 in the stator 1. The lower part of Figure 3 shows a portion of the bottom view of the stator 1. In the bottom view, the shape of the slot SL1 is shown by diagonal lines. Referring to Figures 2 and 3 in addition to Figure 1, the stator 1 has a stator core 10 and a plurality of coils 20.

[0022] The stator core 10 is a magnetic material. The stator core 10 has, for example, electromagnetic steel sheets stacked in the radial direction B. In the stator core 10, a single strip of steel sheet constituting the electromagnetic steel sheet is wound around a central axis P and stacked in the radial direction B.

[0023] In Figure 3, of the strip-shaped steel sheets that are stacked radially B by being wound a predetermined number of turns in the stator core 10, the first layer located in the first layer in the radial direction is shown as [1], the nth layer located in the nth layer of the strip-shaped steel sheets is shown as [n], and the mth layer located in the mth layer of the strip-shaped steel sheets is shown as [m]. n and m are natural numbers greater than 1, and m > n.

[0024] Furthermore, in the following description, each layer of the stator 1 when viewed radially will be referred to as the first layer portion, ..., the nth layer portion, ..., and the mth layer portion, starting from the inside of the radial direction B. Details of the manufacturing method of the stator 1 having such a stator core 10 will be described later. The stator core 10 has a core back portion 11 and a plurality of teeth portions 12.

[0025] The core back portion 11 is annular in shape with a central axis P as its axis. When viewed in the axial direction A, the inner or outer circumferential edge of the core back portion 11 is circular. When viewed in the axial direction A, the inner or outer circumferential edge of the core back portion 11 may be polygonal. The core back portion 11 has a plurality of grooves 111 that are recessed in the axial direction A and extend from the inside to the outside in the radial direction B of the core back portion 11.

[0026] Multiple teeth portions 12 protrude axially from one surface of the core back portion 11 in the axial direction A and are positioned in a line in the circumferential direction C.

[0027] Between adjacent teeth 12 in the circumferential direction C, multiple slots SL1 are formed in the circumferential direction C. The circumferential width of the teeth 12 is larger when viewed in the axial direction A, from the inside in the radial direction B to the radially outer end, and increases towards the radially outer B1. The teeth 12 has a teeth chamfer 121 at the radially outer end that expands the circumferential width of the slot SL1. The teeth chamfer 121 is located at the end of the radially outer end where the groove 111 has the groove chamfer 112.

[0028] The multiple grooves 111 are located on the other side of the core back portion 11 in the axial direction A. That is, the multiple grooves 111 are located on the opposite side of the core back portion 11 from the teeth portion 12 in a plan view of the stator 1. The multiple grooves 111 are located on the core back portion 11 at equal intervals in the circumferential direction C and around the entire circumference of the core back portion 11. The grooves 111 are arc-shaped when viewed radially B of the stator 1.

[0029] The groove portion 111 has a groove chamfer portion 112 at its radially outward end that increases the circumferential width of the groove portion 111.

[0030] The tooth chamfered portion 121 and the groove chamfered portion 112 are located radially outward B1 from, for example, the mth layer portion of the stator core 10. Because the stator core 10 has the tooth chamfered portion 121, the coil 20 can be easily placed in the slot SL1.

[0031] The coil 20 is located within a plurality of slots SL1. The coil 20 has an annular portion 21 and a pair of lead portions 22. The annular portion 21 is inserted into the teeth portion 12 of the stator core 10. Several coils 20 arranged in a continuous circumferential direction C include coils that are electrically connected to the lead portions 22 of adjacent coils 20 and coils that are connected by the lead portions 22 to connecting wires such as busbars (not shown). The lead portions 22 are electrically connected by the connecting wires such as busbars to the lead portions 22 of other coils 20 or to the power supply of each phase. The lead portions 22 are also electrically connected, for example, by welding to the lead portions 22 of other coils 20.

[0032] (Positional relationship between the center line of the slot and the center line of the groove) Referring to Figure 3, when viewing the stator core 10 of the stator 1 in the axial direction A, the center line CL1 of the slot SL1 and the center line CL2 of the groove 111 are located at different positions in the circumferential direction C. The center line CL1 of the slot SL1 is parallel to the center line CL2 of the groove 111, which is located adjacent to one side C1 in the circumferential direction.

[0033] (Comparison of assembly methods) (Conventional case) Figure 4 is a diagram illustrating the center line CL100 of the slot SL100 and the center line CL200 of the groove 1110 in the stator core 1000 of the stator 900 according to a conventional example. Figure 5 is a diagram illustrating the formation process of the strip steel plate WK100 that constitutes the stator core 1000 according to a conventional example. The lower part of Figure 4 shows a part of the bottom view of the stator core 1000. In the bottom view, the shape of the slot SL100 is shown by diagonal lines. In Figure 5, the punched-out portion is shown by diagonal lines.

[0034] Referring to Figures 4 and 5, the stator core 1000 of the conventional stator 900 is formed by winding a strip of steel sheet WK100, which has slot-shaped portions WK110 and groove-shaped portions WK120 punched out, in a ring shape for a predetermined number of turns. This forms a stator core 1000 in which electromagnetic steel sheets are laminated in the radial direction B.

[0035] Referring to Figure 4, in the conventional example, when viewing the stator 900 in the axial direction A, the center line CL100 of the slot SL100 and the center line CL200 of the groove 1110 extend radially B at different positions in the circumferential direction C. Also, the center line CL200 of the groove 1110 is also the center line of the tooth portion 1200 in the circumferential direction C. The tooth portion 1200 has a tapered shape that narrows radially inward B2 when viewed in the axial direction A. In the stator core 1000, the center line CL200 of the groove 1110 is located in the center of the center lines CL100 of two adjacent slots SL100 in the circumferential direction C.

[0036] Figure 5 shows the first layer portion of the strip steel sheet WK100, the nth layer portion of the strip steel sheet WK100, and the mth layer portion of the strip steel sheet WK100. n and m are natural numbers greater than 1, and m > n. When viewing the stator core 1000 in the radial direction, each layer is also referred to as the first layer portion, ..., the nth layer portion, ..., and the mth layer portion, starting from the inside of the radial direction B.

[0037] The strip steel sheet WK100 is formed by punching out slot-shaped portions WK110 from the original strip steel sheet WK900 using a slot-forming punch M110, and punching out groove-shaped portions WK120 using a groove-forming punch M120. The slot-shaped portions WK110 and groove-shaped portions WK120 are punched out one by one while the original strip steel sheet WK900 is moved longitudinally at a predetermined feed rate.

[0038] The circumferential width of the teeth portion 1200 increases towards the radially outward direction. Therefore, the pitch L100_n of the center line CL100 of the slot SL100 in the nth layer portion of the strip steel plate WK100 is greater than the pitch L100_1 of the center line CL100 of the slot SL100 in the first layer portion of the strip steel plate WK100. Also, the pitch L100_m of the center line CL100 of the slot SL100 in the mth layer portion of the strip steel plate WK100 is greater than the pitch L100_n of the center line CL100 of the slot SL100 in the nth layer portion of the strip steel plate WK100.

[0039] In the following explanation, unless otherwise specified, pitches L100_1, L100_n, and L100_m will simply be referred to as pitch L100. The pitch L100 of the center line CL100 of slot SL100 is changed, for example, for each layer of laminated strip steel plates.

[0040] Further, as described above, the center line CL200 of the groove portion 1110 is located at the center of the center lines CL100 of two adjacent slots SL100 in the circumferential direction C. The center line CL200 of the groove portion 1110 is displaced longitudinally from the center line CL100 of the slot SL100 by the pitches L200_1, L200_n, L200_m of the center line CL200 of the groove portion 1110. In the following description, when the pitches L200_1, L200_n, L200_m are not particularly distinguished, they are simply denoted as pitch L200.

[0041] Since the pitch L100 of the center line CL100 of the slot SL100 is changed for each layer, the pitch L200 between the center line CL100 of the slot SL100 and the center line CL200 of the groove portion 1110 is different for each layer.

[0042] Therefore, in order to form the strip steel plate WK100, a device is used that changes the longitudinal interval between the slot forming punch M110 and the groove forming punch M120 to the pitch L200 corresponding to the layer. With this device, while moving the original strip steel plate WK900 longitudinally at a feed amount of the pitch L200 corresponding to the layer, the slot-shaped portion WK110 and the groove-shaped portion WK120 are alternately punched. Therefore, the number of punching shots is the sum of the number of times the slot-shaped portion WK110 is punched and the number of times the groove-shaped portion WK120 is punched.

[0043] (Manufacturing method of the stator of the present embodiment) FIG. 6 is a diagram showing the punching step S11 in the manufacturing method S1 of the stator 1. FIG. 7 is a diagram showing the stator core forming step S12 in the manufacturing method S1 of the stator 1. In FIG. 6, the punched portions are indicated by oblique lines.

[0044] (Punching step) First, referring to FIGS. 3 and 6, in the punching step S11, in the original strip steel plate WK1, the shapes of the plurality of slots SL1 and the shape of the core back portion 11 are punched, and the shapes of the plurality of groove portions 111 are punched in the core back portion 11.

[0045] Specifically, the strip steel plates WK10 of the first layer portion, the nth layer portion, and the mth layer portion are formed by punching out the slot-shaped portion WK11 from the original strip steel plate WK1 with the slot forming punch M11 and punching out the groove-shaped portion WK12 with the groove forming punch M12.

[0046] The strip steel plates WK10 of the first layer portion, the nth layer portion, and the mth layer portion may or may not be continuous in each layer. The slot-shaped portion WK11 is located on one side in the width direction of the strip steel plate WK10, and the groove-shaped portion WK12 is located on the other side in the width direction of the strip steel plate WK10.

[0047] Since the circumferential width of the tooth portion 12 increases toward the outer side in the radial direction, the pitch L1 of the center line CL1 of the slot SL1 increases in the order of the pitch L1_1 of the first layer portion, the pitch L1_n of the nth layer portion, and the pitch L1_m of the mth layer portion.

[0048] On the other hand, the center line CL2 of the groove portion 111 is located at a position longitudinally shifted by the pitch L2 with respect to the center line CL1 of the slot SL1 regardless of the number of layers. The pitch L2 is a dimension smaller than the pitch L1_1 of the first layer portion. That is, the distance between the center line CL2 of the groove portion 111 and one of the center lines CL1 of two adjacent slots SL1 is the same pitch L2 in each layer. Therefore, the center line CL2 of the groove portion 111 is located at an interval of the pitch L2 in the longitudinal direction with respect to one of the center lines CL1 of two adjacent slots SL1 regardless of the number of layers. In contrast, the distance between the center line CL2 of the groove portion 111 and the other of the center lines CL1 of two adjacent slots SL1 is different for each layer.

[0049] As described above, in the punching process S11, by an apparatus in which the groove forming punch M12 is arranged to be longitudinally shifted by the pitch L2 with respect to the slot forming punch M11, in each layer, first, the slot SL1 and the groove portion 111 are punched out from the original strip steel plate WK1 (slot and groove portion forming process). Further, after the slot and groove portion forming process, the original strip steel plate WK1 is moved in the longitudinal direction by a predetermined feed amount (steel plate moving process). By repeating the slot and groove portion forming process and the steel plate moving process, the strip steel plate WK10 is formed.

[0050] This allows the slots SL1 and grooves 111 to be formed in a layer-by-layer manner, with the longitudinal positions of the slots SL1 and grooves 111 being changed relative to the original strip steel sheet WK1. Furthermore, the longitudinal pitch of the slot-forming punch M11 and groove-forming punch M12 does not need to be changed for each layer, and can remain at the pitch L2. Therefore, the production efficiency of the stator 1 can be improved.

[0051] Furthermore, in the punching process S11, the amount of feed in the longitudinal direction of the strip steel plate WK10 is adjusted for each layer in the steel plate moving process, and multiple slots SL1 and multiple grooves 111 are punched out in the slot and groove formation process. This changes the circumferential width of the teeth 12 in each layer of the strip steel plate WK10 that is stacked radially B in the stator core 10.

[0052] This allows the circumferential width of the teeth portion 12 to be varied according to the position in the radial direction B, even when the strip-shaped steel plate WK10 is wound around an axis and laminated in the thickness direction to form the stator core 10 in the radial direction B. More specifically, the punching process S11 described above allows the formation of teeth portion 12 whose circumferential width increases as it moves radially outward B1. Therefore, a stator core 10 that allows the coil 20 to be easily placed in the slot SL1 can be efficiently manufactured.

[0053] Furthermore, in the punching process S11, the strip-shaped steel plate WK10 can be formed by simultaneously punching out the slot-shaped portion WK11 which becomes the slot SL1 and the groove-shaped portion WK12 which becomes the groove 111. Therefore, the number of punching shots is halved compared to the conventional method in which the slot-shaped portion WK110 and the groove-shaped portion WK120 are punched out alternately.

[0054] This allows the stator core 10 to be formed easily and quickly. Therefore, the production efficiency of the stator core 10 can be improved.

[0055] Furthermore, as described above, the slot-shaped portion WK11 is located on one side in the width direction of the original strip-shaped steel plate WK1, and the groove-shaped portion WK12 is located on the other side in the width direction of the original strip-shaped steel plate WK1. Therefore, in the punching process S11, the groove portion 111 can be punched out of the strip-shaped steel plate WK1 at a position opposite to the teeth portion 12 in the core back portion 11 in a plan view of the stator 1.

[0056] This improves the rigidity of the stator core 10 compared to when the groove is formed on the opposite side of the slot SL1 in the core back portion 11. Therefore, it is possible to produce a stator core 10 that maintains rigidity while reducing weight with the groove 111.

[0057] (Stator core formation process) Next, referring to Figures 3 and 7, in the stator core formation process S12, the strip-shaped steel plates WK10 punched out in the punching process S11 are stacked in the thickness direction to form the stator core 10 in the radial direction B.

[0058] In the punching step S11 of the exemplary stator 1 manufacturing method S1 described above, the original strip-shaped steel plate WK1 is punched out with each of the multiple slots SL1 and each of the multiple grooves 111 in the same positional relationship.

[0059] This allows for easy formation of the slot SL1 and groove 111 in the strip steel plate WK10 without changing the pitch (spacing) between the slot SL1 and the groove 111. Therefore, the stator core 10 can be easily formed. Consequently, the production efficiency of the stator 1 can be improved.

[0060] Furthermore, in the punching process S11, multiple slots SL1 and multiple grooves 111 are punched out of the strip steel sheet WK1 in the same positional relationship. The strip steel sheet WK1 may be a single sheet of steel, or it may be multiple sheets of steel, each with a different layer. In the stator core forming process S12, the strip steel sheet WK10 is wound around its axis and laminated in the thickness direction to form the stator core 10 in the radial direction B.

[0061] This allows the stator core 10 to be formed using at least one strip of steel plate WK1. Therefore, the stator core 10 can be easily formed. Consequently, the production efficiency of the stator 1 can be improved.

[0062] The exemplary stator 1 described above comprises a stator core 10 having an annular core back portion 11 centered on a central axis P as an axis, and a plurality of teeth portions 12 projecting in the axial direction A from one surface of the core back portion 11 and arranged in the circumferential direction C, with a plurality of slots SL1 arranged in the circumferential direction C between adjacent teeth portions 12 in the circumferential direction C, and coils 20 located within the plurality of slots SL1. The stator core 10 has steel plates stacked in the radial direction B. The core back portion 11 has a plurality of groove portions 111 that are recessed in the axial direction A and extend from the radially inner side to the radially outer side of the core back portion 11. The center line CL1 of the slots SL1 and the center line CL2 of the groove portions 111 are parallel when viewing the stator core 10 in the axial direction A.

[0063] The stator core 10, which is made up of steel plates stacked in the radial direction B, has multiple grooves 111 in the core back portion 11, thereby reducing its weight.

[0064] Furthermore, as described above, in the case of a stator core 10 where the center line CL1 of the slot SL1 and the center line CL2 of the groove 111 are parallel when viewed in the axial direction A, multiple slots SL1 and grooves 111 of the core back portion 11 are formed in the steel plate in the same positional relationship. This makes it easy to perform press forming when forming the slots SL1 and grooves 111 in the steel plate. Therefore, the production efficiency of the stator 1 can be improved.

[0065] Furthermore, the multiple grooves 111 are located on the other side of the core back portion 11.

[0066] This makes it possible to reduce the weight of the other side of the core back portion 11 compared to a case where grooves are not formed on the other side of the core back portion 11. Furthermore, since the weight of the core back portion 11 can be reduced, the weight of the stator 1 and motor 100 can also be reduced.

[0067] Furthermore, each of the multiple grooves 111 is positioned such that, when the core back portion 11 is viewed in the axial direction A, at least a portion of each of the multiple teeth portions 12 overlaps with each of the multiple teeth portions 12.

[0068] As a result, at least a portion of the groove 111 is positioned axially A relative to the teeth portion 12 on the other surface of the core back portion 11, thereby ensuring the rigidity of the stator core 10 having multiple grooves 111.

[0069] Furthermore, since the groove 111 and slot SL1 can be formed together in the strip steel plate WK10, the production efficiency of the stator 1 can be improved.

[0070] Furthermore, the multiple grooves 111 are located on the core back portion 11 at equal intervals in the circumferential direction C and around the entire circumference of the core back portion 11.

[0071] This allows for a further reduction in the weight of the core back portion 11, and since there is no need to change the spacing between the multiple grooves 111 when forming them in the core back portion 11, the multiple grooves 111 can be easily formed. Therefore, the production efficiency of the stator 1 can be improved.

[0072] Furthermore, the stator core 10 is constructed by winding at least one strip-shaped steel plate WK10, which constitutes the steel plate, around an axis and stacking them radially in the direction B.

[0073] This allows the stator core 10 to be produced using at least one strip of steel plate WK10, thereby improving the production efficiency of the stator 1.

[0074] Furthermore, the motor 100 described above has a rotor 50 that rotates around the axis of the stator 1 relative to the stator 1. The motor 100 described above has a stator 1 that can be produced more efficiently.

[0075] (Method for forming tooth chamfers and groove chamfers) Figure 8 is a diagram illustrating the method for forming tooth chamfers 121 and groove chamfers 112. Referring to Figure 8, as described above, the tooth portion 12 has a tooth chamfer 121 at its radially outward end. The groove portion 111 has a groove chamfer 112 at its radially outward end. In Figure 8, the chamfer-forming layer 101 at the radially outward end of the stator 1 is shown by shading.

[0076] The chamfer-forming layer 101 is composed of layers from the outermost layer of the radially outward B1 to a predetermined layer among the layers of the stator core 10, which is formed by laminating strip-shaped steel plates WK10 in the thickness direction. The chamfer-forming layer 101 is located radially outward B1 than, for example, the mth layer of the stator core 10.

[0077] In the strip-shaped steel plate WK10_x on which the chamfer-forming layer 101 is formed, the width WD12 of the slot-shaped portion WK11 is greater than the width WD11 of the slot-forming punch M11. Also, in the strip-shaped steel plate WK10_x, the width WD22 of the groove-shaped portion WK12 is greater than the width WD21 of the groove-forming punch M12.

[0078] Therefore, the original strip of steel WK1 is fed longitudinally by the difference between the width WD12 of the slot-shaped portion WK11 and the width WD11 of the slot-forming punch M11, and the original strip of steel WK1 is punched out multiple times by the slot-forming punch M11 and the groove-forming punch M12.

[0079] As a result, a slot-forming punch M11 with a width WD11 can punch out a slot-shaped portion WK11 with a width WD12 that is larger than WD11. In addition, a groove-forming punch M12 with a width WD21 can punch out a groove-shaped portion WK12 with a width WD22 that is larger than WD21.

[0080] As described above, the chamfering layer 101 of the stator core 10 can be formed by laminating the punched strip steel plates WK10_x. The chamfering layer 101 has a teeth chamfering portion 121 and a groove chamfering portion 112. The groove chamfering portion 112 is located at the radially outward end of the teeth portion 12 which has the teeth chamfering portion 121, and is located in the same direction as the teeth chamfering portion 121 relative to the slot SL1 in the circumferential direction C relative to the groove portion 111.

[0081] As described above, in a stator core 10 obtained by stacking strip-shaped steel plates WK10 in the radial direction B, where the slot SL1 and groove 111 of the core back portion 11 are formed in the same positional relationship, if the teeth portion 12 has a teeth chamfer 121 that expands the circumferential width of the slot SL1, the groove 111 has a groove chamfer 112 at a predetermined position in the circumferential direction C relative to the teeth chamfer 121, in the same positional relationship as the circumferential direction C relationship between the slot SL1 and the groove 111. In other words, in a stator core 10 having the above configuration, the slot SL1 and groove 111 are formed on the original strip-shaped steel plate WK1 so that the positional relationship between the slot SL1 and the groove 111 is the same, the stator core 10 can be produced more efficiently compared to the case where the positional relationship between the slot and the groove is changed to form the stator core. Therefore, the production efficiency of the stator 1 can be improved.

[0082] (Other Embodiments) Although embodiments of the present invention have been described above, the embodiments described above are merely examples for carrying out the present invention. Therefore, the invention is not limited to the embodiments described above, and it is possible to carry out the invention by appropriately modifying the embodiments described above without departing from the spirit of the invention.

[0083] In the above embodiment, the motor 100 has stators 1 located on both the one and the other axial A of the rotor 50. However, the motor may have one stator located on either one or the other axial position of the rotor.

[0084] In the above embodiment, the stators 1 located on both sides of the axial direction A of the rotor 50 are the same shape as each other except that their orientation in the axial direction A is opposite. However, the stator located on one side of the rotor's axial direction and the stator located on the other side may have different shapes.

[0085] In the above embodiment, the groove portion 111 has a groove chamfer portion 112 at its radially outward end that increases the circumferential width of the groove portion 111. The teeth portion 12 has a teeth chamfer portion 121 at its radially outward end that increases the circumferential width of the slot SL1. However, the groove portion may also have a groove chamfer portion at its radially inward end. In this case, the teeth portion may also have a teeth chamfer portion at its radially inward end. The groove portion and the teeth portion may have groove chamfer portions and teeth chamfer portions at both radial ends.

[0086] In the above embodiment, the plurality of grooves 111 are located on the other side of the core back portion 11. However, the plurality of grooves may be located on one side of the core back portion.

[0087] In the above embodiment, each of the multiple grooves 111 is located such that, when viewed from the core back portion 11 in the axial direction A, it overlaps with at least a portion of each of the multiple teeth portions 12. However, each of the multiple grooves may be located such that, when viewed from the core back portion in the axial direction, it is offset circumferentially from the multiple teeth portions.

[0088] In the above embodiment, the multiple grooves 111 are located on the core back portion 11 at equal intervals in the circumferential direction C and around the entire circumference of the core back portion 11. However, the multiple grooves do not have to be located at equal intervals in the circumferential direction on the core back portion. The multiple grooves do not have to be located around the entire circumference of the core back portion.

[0089] In the above embodiment, the groove 111 is arc-shaped when viewed radially B on the stator 1. However, the groove does not have to be arc-shaped when viewed radially on the stator. The groove may be triangular, square, or polygonal when viewed radially on the stator. When the groove is arc-shaped, weight can be reduced while suppressing a decrease in strength compared to when it is triangular.

[0090] In the above embodiment, when viewing the core back portion 11 in the axial direction A, one groove 111 is located at a position that overlaps with the teeth portion 12. However, when viewing the core back portion in the axial direction, several grooves may be located at positions that overlap with one tooth portion. Figure 9 is a schematic side view showing a part of the stator core 10. Referring to Figure 9, the stator core 10 has a core back portion 11 and a plurality of teeth portions 12. The plurality of grooves 111 are located on the other side of the core back portion 11. For example, when viewing the core back portion 11 in the axial direction A, two grooves 1111 and 1112 of the plurality of teeth portions 12 are located at positions that overlap with one tooth portion 12. The center line CL1 of the slot SL1 is parallel to the center line CL21 of groove 1111 and the center line CL22 of groove 1112.

[0091] Although not specifically described in the above embodiment, when forming a stator core with multiple strip-shaped steel plates, each layer being different, the steel plates may be stacked radially by bending the strip-shaped steel plates into an annular shape and arranging them concentrically.

[0092] In the above embodiment, in punching step S11, the slot-shaped portion WK11 and the groove-shaped portion WK12 are punched out simultaneously from the original strip-shaped steel plate WK1. However, in the punching step, the slot-shaped portion may be punched out first and then the groove-shaped portion, or the groove-shaped portion may be punched out first and then the slot-shaped portion.

[0093] In the above embodiment, in punching step S11, a groove 111 is punched out of the original strip-shaped steel plate WK1 at a position opposite to the teeth portion 12 in the core back portion 11 when viewed from above of the stator 1. However, in the punching step, the groove may also be punched out at a position on the same side as the teeth in the core back portion when viewed from above of the stator.

[0094] (Example Configuration) This technology can also be configured as follows:

[0095] (1) The stator has an annular core back portion centered on an axis, and a plurality of teeth portions that protrude axially from one surface of the core back portion and are arranged in the circumferential direction, and a plurality of slots arranged in the circumferential direction are formed between adjacent teeth portions in the circumferential direction, and coils located in the plurality of slots. The stator core has steel plates stacked in the radial direction. The core back portion has a plurality of groove portions that are recessed in the axial direction and extend from the radially inner side to the radially outer side of the core back portion. The center lines of the slots and the center lines of the groove portions are parallel when the stator core is viewed in the axial direction.

[0096] (2) In the stator described in (1), the plurality of grooves are located on the other surface of the core back portion.

[0097] (3) In the stator described in (2), each of the plurality of grooves is located such that, when viewed in the axial direction of the core back portion, it overlaps with at least a portion of each of the plurality of teeth portions.

[0098] (4) In the stator described in any one of (1) to (3), the plurality of grooves are located at equal intervals in the circumferential direction on the core back portion and around the entire circumference of the core back portion.

[0099] (5) In the stator described in any one of (1) to (4), the stator core is formed by stacking at least one strip of steel plate that constitutes the steel plate, wound around the axis.

[0100] (6) In the stator described in any one of (1) to (5), the teeth portion has a teeth chamfer at at least one end of the radial ends that widens the circumferential width of the slot, and the groove portion has a groove chamfer at the end of the radial ends on which the teeth portion has the teeth chamfer, and at a position relative to the groove portion in the circumferential direction in the same direction as the teeth chamfer relative to the slot that widens the circumferential width of the groove portion.

[0101] (7) A motor having a stator as described in any one of (1) to (6), and a rotor that rotates with respect to the stator about the axis of the stator.

[0102] (8) A method for manufacturing a stator has a stator core having an annular core back portion centered on an axis, and a plurality of teeth portions that protrude axially from one surface of the core back portion and are arranged in the circumferential direction, and a plurality of slots arranged in the circumferential direction between adjacent teeth portions in the circumferential direction. The method for manufacturing a stator has a punching step of punching out the plurality of slots and the core back portion from a steel plate and punching out a plurality of groove portions from the core back portion, and a stator core forming step of stacking the steel plates punched out in the punching step in the thickness direction to form the stator core in the radial direction. In the punching step, each of the plurality of slots and each of the plurality of groove portions are punched out from the steel plate in the same positional relationship.

[0103] (9) In the method for manufacturing a stator described in (8), in the punching step, each of the plurality of slots and each of the plurality of grooves are punched out of at least one strip of steel plate constituting the steel plate in the same positional relationship. In the stator core forming step, the strip of steel plate is wound around the axis and laminated in the thickness direction to form the stator core in the radial direction.

[0104] (10) In the method for manufacturing a stator described in (9), the punching step comprises a slot and groove forming step in which the slot and groove are punched out into the strip of steel sheet, and a steel sheet moving step in which the strip of steel sheet is moved in the longitudinal direction by a predetermined amount after the slot and groove forming step.

[0105] (11) In the method for manufacturing a stator described in (10), in the punching step, the amount of feed in the longitudinal direction of the strip steel plate is adjusted in the steel plate moving step, and the width of the teeth portion is changed in each layer of the strip steel plate stacked radially in the stator core by punching out the plurality of slots and the plurality of grooves in the slot and groove portion forming step.

[0106] (12) In the method for manufacturing a stator described in any one of (8) to (11), the punching step is performed by punching out the slot and the groove simultaneously from the steel plate.

[0107] (13) In the method for manufacturing a stator described in any one of (8) to (12), in the punching step, the groove is punched out of the steel plate at a position on the opposite side of the teeth portion in the core back portion when viewed in plan.

[0108] The configuration of the present invention is applicable to a stator having a stator core and coils.

[0109] 1: Stator 10: Stator core 11: Core back section 12: Teeth section 20: Coil 21: Annular section 22: Lead section 50: Rotor 100: Motor 101: Chamfer forming layer 111: Groove section 112: Groove chamfer section 121: Teeth chamfer section CL1: Center line of slot CL2: Center line of groove section P: Central axis SL1: Slot WK1: Original strip steel plate WK10, WK10_x: Strip steel plate WK11: Slot-shaped section WK12: Groove-shaped section

Claims

1. A stator having a stator core having an annular core back portion centered on an axis, and a plurality of teeth portions that protrude axially from one surface of the core back portion and are arranged in the circumferential direction, wherein a plurality of slots are formed between adjacent teeth portions in the circumferential direction, and coils are located within the plurality of slots, wherein the stator core has steel plates laminated in the radial direction, the core back portion has a plurality of groove portions that are recessed in the axial direction and extend from the radially inner side to the radially outer side of the core back portion, and the center lines of the slots and the center lines of the groove portions are parallel when the stator core is viewed in the axial direction.

2. A stator according to claim 1, wherein the plurality of grooves are located on the other surface of the core back portion.

3. A stator according to claim 2, wherein each of the plurality of grooves is located such that, when viewed axially from the core back portion, at least a portion of each of the plurality of teeth portions overlaps with each of the teeth portions.

4. A stator according to claim 1, wherein the plurality of grooves are located around the core back portion at equal intervals in the circumferential direction and around the entire circumference of the core back portion.

5. A stator according to claim 1, wherein the stator core is formed by winding at least one strip-shaped steel plate constituting the steel plate around the axis and stacking them radially.

6. A stator according to claim 1, wherein the teeth portion has a teeth chamfer at at least one end of both radial ends that increases the circumferential width of the slot, and the groove portion has a groove chamfer at the end of both radial ends on the side where the teeth portion has the teeth chamfer, and at a position relative to the groove portion in the circumferential direction in the same direction as the teeth chamfer relative to the slot that increases the circumferential width of the groove portion.

7. A motor comprising: a stator according to any one of claims 1 to 6; and a rotor that rotates relative to the stator about the axis of the stator.

8. A method for manufacturing a stator having a stator core having an annular core back portion centered on an axis, and a plurality of teeth portions that protrude axially from one surface of the core back portion and are arranged in the circumferential direction, wherein a plurality of slots are arranged in the circumferential direction between adjacent teeth portions in the circumferential direction, comprising: a punching step of punching out the plurality of slots and the core back portion from a steel plate, and punching out a plurality of groove portions from the core back portion; and a stator core forming step of stacking the steel plates punched out in the punching step in the thickness direction to form the stator core in the radial direction, wherein in the punching step, each of the plurality of slots and each of the plurality of groove portions are punched out from the steel plate in the same positional relationship.

9. A method for manufacturing a stator according to claim 8, wherein in the punching step, at least one strip-shaped steel plate constituting the steel plate is punched out with each of the plurality of slots and each of the plurality of grooves in the same positional relationship, and in the stator core forming step, the strip-shaped steel plate is wound around the axis and laminated in the thickness direction to form the stator core in the radial direction.

10. A method for manufacturing a stator according to claim 9, wherein the punching step comprises: a slot and groove forming step of punching the slots and grooves into the strip steel plate; and a steel plate moving step of moving the strip steel plate in the longitudinal direction by a predetermined feed amount after the slot and groove forming step.

11. A method for manufacturing a stator according to claim 10, wherein in the punching step, the amount of feed in the longitudinal direction of the strip steel plate is adjusted in the steel plate moving step, and the width of the teeth portion is changed in each layer of the strip steel plate stacked radially in the stator core by punching out the plurality of slots and the plurality of grooves in the slot and groove portion forming step.

12. A method for manufacturing a stator according to any one of claims 8 to 11, wherein in the punching step, the slot and the groove are punched out simultaneously from the steel plate.

13. A method for manufacturing a stator according to claim 8, wherein in the punching step, the groove portion is punched out of the steel plate at a position opposite to the teeth portion in the core back portion when viewed in plan.

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