Stator core, rotary electrical machine, and pressurizing jig

Abstract

Provided is a stator core (30) comprising a plurality of laminated electromagnetic steel sheets (40) and adhesive parts (100) that are respectively disposed between electromagnetic steel sheets (40) which are adjacent in the lamination direction, said stator core being characterized in that: the electromagnetic steel sheets (40) each include an annular core back (41), a plurality of teeth (42) that are spaced in the circumferential direction and that protrude in the radial direction from the core back (41), and connecting part (43) that connects tip ends of adjacent teeth (42); and the adhesive parts (100) include first adhesive parts (110) that surround spaces formed by the core backs (41) of the electromagnetic steel sheets (40), adjacent teeth (42), and the connecting parts (43).

Description

Stator core, rotating electric machine and pressure jig

[0001] The present invention relates to a stator core, a rotating electric machine, and a pressing jig. This application claims priority to Japanese Patent Application No. 2024-124581, filed on July 31, 2024, the contents of which are incorporated herein by reference.

[0002] As the electrification of automobiles advances, motors used in electric vehicles are expected to be compact and have high output. Thermal management of motors has also become an important issue. To address this issue, cooling technologies such as direct oil cooling of the interior of a motor have been adopted in recent years. One cooling method for the interior of a motor is to form a sealed structure for each slot of a stator core and directly cool the heat generated by the coil windings by flowing a cooling medium from the outside. For example, in Patent Document 1, in order to cool the windings inside the slots, the windings are moved toward the inner diameter of the slots and a gap is provided on the outer diameter side, ensuring a path for the cooling medium, i.e., air.

[0003] JP 2014-128041 A

[0004] However, if a cooling medium leaks outside the slots through gaps between the laminated electromagnetic steel sheets used to form the stator core, the cooling medium may act as a resistance to the rotational force of the motor. Furthermore, particularly when the cooling medium is liquid, if the cooling medium leaks, it becomes necessary to replenish the leaked cooling medium, which requires a structure or device to recover the leaked cooling medium, resulting in increased costs. On the other hand, if additional components are required to seal the slots as a countermeasure against cooling medium leakage, there is a concern that the space factor of the coil windings may decrease. Therefore, the present inventors investigated a sealed stator core structure that requires as few additional components as possible.

[0005] The present invention has been made in view of the above, and an object of the present invention is to provide a stator core that can prevent the cooling medium flowing through the slots from leaking from the stator core.

[0006] (1) A stator core according to one aspect of the present invention comprises a plurality of stacked electromagnetic steel sheets and adhesive portions respectively arranged between adjacent electromagnetic steel sheets in the stacking direction, wherein each of the electromagnetic steel sheets includes an annular core back, a plurality of teeth spaced circumferentially and protruding radially from the core back, and a connecting portion connecting the tips of adjacent teeth, and the adhesive portion includes a first adhesive portion surrounding a space formed by the core backs of the plurality of electromagnetic steel sheets, the adjacent teeth, and the connecting portion.

[0007] (2) In the stator core described in (1) above, the first adhesive portion may have: a circumferential adhesive portion provided on each of the adjacent teeth, an inner adhesive portion provided on the connecting portion and connecting radially inner sides of the circumferential adhesive portions of each of the adjacent teeth, and an outer adhesive portion provided on the core back and connecting radially outer sides of the circumferential adhesive portions of each of the adjacent teeth. (3) In the stator core described in (2) above, the circumferential adhesive portion may be provided on an end of each of the adjacent teeth closest to the space, the inner adhesive portion may be provided at least on a radially outer end of the connecting portion, and the outer adhesive portion may be provided on a radially inner end of the core back. (4) In the stator core described in (2) or (3) above, the compressive stress remaining in the region of the connecting portion where the inner adhesive portion is provided may be greater than at least one of the compressive stress remaining in the region of the tooth where the circumferential adhesive portion is provided or the region of the core back where the outer adhesive portion is provided. (5) In the stator core described in (1) above, the first adhesive portion may have an inner ring adhesive portion provided in an annular shape across the tip portions of the plurality of teeth and the plurality of connecting portions, and an outer ring adhesive portion provided in an annular shape across the core back. (6) In the stator core described in (5) above, the compressive stress remaining in the region of the connecting portion where the inner ring adhesive portion is provided may be greater than the compressive stress remaining in at least one of the region of the tooth where the inner ring adhesive portion is provided or the region of the core back where the outer ring adhesive portion is provided. (7) In the stator core described in any one of (1) to (6) above, the adhesive portion may further include a second adhesive portion provided at a position different from the first adhesive portion. (8) In the stator core described in (7) above, the first adhesive portion may be formed by solidifying a first adhesive that exhibits adhesive strength according to pressure during bonding, and a compressive stress remaining in a region of the connecting portion where the first adhesive portion is provided may be greater than a compressive stress remaining in a region of the electromagnetic steel sheet where the second adhesive portion is provided.(9) In the stator core described in (7) or (8) above, the second adhesive portion may be provided in all portions between the electromagnetic steel sheets where the first adhesive portion is not present.

[0008] (10) A rotating electric machine according to one aspect of the present invention includes the stator core according to any one of (1) to (9) above.

[0009] (11) A pressing tool according to one aspect of the present invention is a pressing tool used in the manufacture of a stator core having a plurality of stacked electromagnetic steel plates and adhesive portions respectively arranged between adjacent electromagnetic steel plates in the stacking direction, wherein the stator core has a plurality of teeth and connecting portions connecting adjacent teeth, and the pressing tool is characterized in that it has a member having irregularities on its pressing surface, and the pressing surface of the member protrudes at least at a position corresponding to the connecting portion.

[0010] According to the stator core of the present invention, the cooling medium flowing through the slots can be prevented from leaking from the stator core.

[0011] FIG. 1 is a diagram for explaining a rotating electric machine according to an embodiment of the present invention, and is a cross-sectional view of a stator and a rotor included in the rotating electric machine, viewed from the lamination direction of the electromagnetic steel sheets. FIG. 2 is a diagram for explaining a first adhesive portion provided for each slot according to an embodiment of the present invention, and corresponds to the enlarged view of the vicinity of the slot in FIG. 1. FIG. 3 is a diagram for explaining a first adhesive portion provided for each slot according to another embodiment of the present invention, and corresponds to the enlarged view of the vicinity of the slot in FIG. 1. FIG. 4 is a diagram for explaining first adhesive portions provided around a plurality of slots according to another embodiment of the present invention, and is a cross-sectional view of a stator core viewed from the lamination direction of the electromagnetic steel sheets. FIG. 5 is a cross-sectional view showing a pressing jig according to an embodiment of the present invention.

[0012] Hereinafter, embodiments of the present invention will be described using examples, but it is obvious that the present invention is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be exemplified, but other numerical values ​​and materials may be applied as long as the effects of the present invention are obtained. Furthermore, the components of the following embodiments can be combined with each other.

[0013] FIG. 1 is a schematic diagram illustrating a rotating electric machine 1 including a stator 10 and a rotor 20. Note that FIG. 1 only illustrates the necessary components for explanation, and therefore omits other components of the rotating electric machine 1. Also, coils and the like included in the stator 10, permanent magnets, magnet insertion holes, gaps, and a rotating shaft included in the rotor 20, are also omitted. FIG. 1 is a cross-sectional view of the stator 10 and rotor 20 included in the rotating electric machine 1, as viewed from the stacking direction of the electromagnetic steel sheets 40 (hereinafter also referred to as the stacking direction), and corresponds to a view of the rotating electric machine 1 cut perpendicular to the stacking direction between adjacent electromagnetic steel sheets 40 in the stacking direction. In other words, FIG. 1 is a cross-sectional view of the stator 10 cut along a radial direction D, for example, between adjacent electromagnetic steel sheets 40. Hereinafter, the radial direction D refers to a direction perpendicular to the central axis C of the stator 10. The circumferential direction R refers to a direction around the central axis C of the stator 10.

[0014] As shown in Fig. 1, in a rotating electric machine 1, a stator 10 and a rotor 20 are disposed so as to share a common central axis C. In general, the stator 10 and the rotor 20 are configured by stacking a plurality of electromagnetic steel sheets in their thickness direction. Adjacent electromagnetic steel sheets in the stacking direction of the electromagnetic steel sheets that make up the stator 10 and the rotor 20 are fixed to each other by adhesive, caulking, or a combination of these. The stator 10 also has a stator core 30.

[0015] First, a stator core 30 according to this embodiment will be described with reference to Fig. 1. As shown in Fig. 1, the stator core 30 according to this embodiment includes a plurality of stacked electromagnetic steel sheets 40 and adhesive portions 100 (first adhesive portions 110) respectively disposed between adjacent electromagnetic steel sheets 40 in the stacking direction. Each electromagnetic steel sheet 40 includes an annular (annular in Fig. 1) core back 41, a plurality of teeth 42 protruding in the radial direction D from the core back 41 at intervals in the circumferential direction R, and connecting portions 43 connecting the tip ends of adjacent teeth 42.

[0016] In this embodiment, the teeth 42 protrude radially inward from the core back 41. That is, when viewed from the stacking direction (see FIG. 1 ), if the outermost edge 41 e and the innermost edge 41 i of the annular core back 41 in the radial direction D are defined as an outer edge 41 e and an innermost edge 41 i, respectively, each of the multiple teeth 42 extends toward the central axis C so as to protrude from the inner edge 41 i of the annular core back 41. The innermost end of each tooth 42 in the radial direction D is the tip of the tooth 42. When viewed from the stacking direction, the outer edge 41 e of the core back 41 coincides with the side surface of the electromagnetic steel sheet 40 (the surface whose length in the stacking direction is the sheet thickness). Furthermore, the tip portions of the teeth 42 are portions that include the tips of the teeth 42, and the connecting portions 43 may be connected to portions of the tip portions of the teeth 42 other than the tips (portions radially outward from the tips). The adhesive portion 100 will be described in detail below, but the adhesive portion 100 includes at least a first adhesive portion 110 and may further include a second adhesive portion 120 .

[0017] The plurality of electromagnetic steel sheets 40 constituting the stator core 30 described above are stacked, and gaps formed inside the stator core 30 by two adjacent teeth 42 of each electromagnetic steel sheet 40, the core back 41 (inner edge 41 i), and the connecting portion 43 are connected in the stacking direction, thereby forming spaces (hereinafter, slots 44) that penetrate the stator core 30 in the stacking direction. Coils 50 (see FIGS. 2 and 3 described below) are housed inside the slots 44. The spaces inside the slots 44 where no coils 50 exist are connected in the stacking direction to connect the outsides of both ends of the slots 44 in the radial direction D, allowing a cooling medium such as cooling water, oil, or gas to flow through. The teeth 42 may protrude radially outward from the core back (also referred to as a yoke). A stator core having such a shape is used in an outer rotor type rotating electric machine.

[0018] 1, the width (length in the radial direction D) of the connecting portion 43 is generally constant in the circumferential direction (the same applies to FIGS. 2 to 4 described below). However, the specific shape of the connecting portion 43 is arbitrary as long as it connects the tips of adjacent teeth 42. For example, the connecting portion 43 may have a portion whose width differs from other positions, and for example, when viewed from the stacking direction, the outer edge of the connecting portion 43 in the radial direction D may be formed by one or more straight lines or arcs.

[0019] In the stator core 30 according to the present embodiment, all of the laminated electromagnetic steel sheets 40 include the above-described connecting portions 43. However, some of the laminated electromagnetic steel sheets 40 may also include the above-described connecting portions 43. In this case, in electromagnetic steel sheets (not shown) that do not include connecting portions 43, instead of the connecting portions 43, gaps may be filled with a resin or the like other than the electromagnetic steel sheets 40 (for example, the same material as the first adhesive portions 110) so as to connect the tips of adjacent teeth. This adhesive portion may be configured to have the same thickness as the electromagnetic steel sheets, thereby surrounding the slots 44 and preventing leakage of coolant from inside the slots 44. The thickness of each electromagnetic steel sheet 40 that forms the stator core 30 may be determined appropriately taking into consideration the magnetic property improvement effect, such as the iron loss improvement effect, manufacturing costs, ease of press punching, and the like.

[0020] Next, the above-mentioned adhesive portion 100 will be described in detail with reference to Figures 2 to 4. Figures 2 to 3 are views corresponding to the enlarged view of the vicinity of slot 44 in Figure 1, and each is a view for explaining a first adhesive portion 110 according to one embodiment of the present invention. Also, Figure 4 is a cross-sectional view of a stator 10 different from the embodiment of Figures 1 to 3, as seen from the stacking direction, similar to Figure 1.

[0021] The adhesive portion 100 is provided on the surface of the electromagnetic steel sheet 40 (the sheet surface facing the stacking direction), which is the surface where the stacked electromagnetic steel sheets 40 face each other. The adhesive portion 100 is formed by solidifying (hardening) an adhesive applied between adjacent electromagnetic steel sheets 40. Two adjacent electromagnetic steel sheets 40 in the stator core 30 may be bonded together by the adhesive portion 100. In other words, the adhesive portion 100 may not bond adjacent electromagnetic steel sheets 40 together at least in part. In other words, the adhesive portion 100 may include a first adhesive portion 110 that does not contribute to fixing the electromagnetic steel sheets 40 together by adhesion, and an adhesive portion (such as a second adhesive portion 120 described below) that contributes to fixing the electromagnetic steel sheets 40 together by adhesion. When the adhesive portion 100 does not entirely bond adjacent electromagnetic steel sheets 40 together, the electromagnetic steel sheets 40 may be fixed together by other fixing means, such as crimping. Examples of types of adhesives that can be used as the adhesive portion 100 include thermosetting adhesives that use polymerization bonding, acrylic adhesives that cure at room temperature, anaerobic adhesives, instant adhesives, and elastomer-containing acrylic adhesives.

[0022] Alternatively, at least a portion of the adhesive portion 100 may be formed by an adhesive coating provided on the entire surface of the electromagnetic steel sheet 40. The adhesive coating is, for example, a type of adhesive that solidifies by heat treatment. In this case, two adjacent electromagnetic steel sheets 40 in the stator core 30 are bonded together by the adhesive coating. The bonding of the electromagnetic steel sheets 40 by the adhesive coating is performed using a pressure jig as described below. The adhesive may be applied over an insulating coating provided on the surface of the electromagnetic steel sheet 40, or may be applied to the surface of the electromagnetic steel sheet 40 without any insulating coating on the surface of the electromagnetic steel sheet 40.

[0023] 2 and 3 , the adhesive portion 100 includes a first adhesive portion 110 surrounding a slot 44 of the stator core 30. More specifically, as shown in FIGS. 2 and 3 , the first adhesive portion 110 may have a circumferential adhesive portion 111, an inner adhesive portion 112, and an outer adhesive portion 113. The circumferential adhesive portion 111 is provided on each of two adjacent teeth 42 (e.g., 42A and 42B). The inner adhesive portion 112 connects the radially inner sides of the circumferential adhesive portions 111 of the adjacent teeth 42 provided on the connecting portion 43. The outer adhesive portion 113 connects the radially outer sides of the circumferential adhesive portions 111 of the adjacent teeth 42 provided on the core back 41. The circumferential adhesive portion 111 may be provided along the radial direction D on each of the two adjacent teeth 42.

[0024] That is, when viewed from the stacking direction, in each slot 44 of the stator core 30, the first adhesive portion 110 is formed so as to surround the corresponding slot 44 by two peripheral adhesive portions 111 that face each other across the slot 44, an inner adhesive portion 112, and an outer adhesive portion 113. Also, when viewed from the stacking direction, each first adhesive portion 110 is formed continuously without interruption.

[0025] In the embodiment shown in FIG. 2 , the circumferential adhesive portion 111 is provided at the end of each adjacent tooth 42 closest to the slot 44, away from the edge (slot circumferential edge 44 a) of each tooth 42. In other words, the circumferential adhesive portion 111 is not provided over the entire tooth 42, but is provided at the circumferential end portion away from the edge. Similarly, the outer adhesive portion 113 is provided at the radially inner end of the core back 41 (not the entire core back 41, but an end portion) away from the slot outer edge 44 c. Note that a portion of the inner edge 41 i and the slot outer edge 44 c overlap. The inner adhesive portion 112 is provided at the radially outer end of the connecting portion 43, away from the radially outer edge (slot inner edge 44 b). In FIG. 2, the distances from the edges of the slot 44 (slot peripheral side edge 44a, slot inner edge 44b, and slot outer edge 44c) of each part constituting the first adhesive portion 110 are generally the same, but there may be parts or positions where the distances are different from the others.

[0026] According to the above-described configuration, the first adhesive portion 110 surrounding the slot 44 can limit the area in which the cooling medium leaks from the slot 44 to the area between the electromagnetic steel sheets 40 to the vicinity of the slot 44 .

[0027] In the embodiment shown in FIG. 3 , the circumferential adhesive portion 111 is provided at the end of each adjacent tooth 42 closest to the slot 44, at a position overlapping the edge (slot circumferential edge 44 a) of each tooth 42. In other words, the circumferential adhesive portion 111 is not provided over the entire tooth 42, but is provided at the circumferential end portion, and when viewed from the stacking direction, the end of the circumferential adhesive portion 111 coincides with the side surface of the electromagnetic steel sheet 40 that forms the slot 44. Similarly, the outer adhesive portion 113 is provided at the radially inner end of the core back 41 (not the entire core back 41, but an end portion) at a position overlapping the inner edge 41 i (slot outer edge 44 c) of the core back 41. The inner adhesive portion 112 is provided at the radially outer end of the connecting portion 43, at a position overlapping the radially outer edge (slot inner edge 44 b). Note that the first adhesive portion 110 may extend to the inner wall of the slot 44 in at least some of the portions that make up the first adhesive portion 110 .

[0028] According to the above configuration, the first adhesive portion 110 surrounding the slot 44 is extended to the edge of the slot 44, thereby preventing leakage of the coolant not only outside the slot 44 but also between adjacent electromagnetic steel sheets 40 (surfaces of the electromagnetic steel sheets 40). Furthermore, assuming that the widths of the portions constituting the first adhesive portion 110 are the same in FIGS. 2 and 3 , the configuration in FIG. 3 positions the first adhesive portion 110 away from the region where magnetic flux mainly flows during operation (the circumferential center region of the teeth 42). This makes the first adhesive portion 110 less likely to obstruct the flow of magnetic flux, which is expected to suppress deterioration of motor characteristics. Furthermore, according to the above configuration, no additional components are required to prevent leakage of the coolant. Therefore, no space is required for additional components, and the opening area of ​​the slot 44 can be secured. Furthermore, since the above configuration does not require additional components, it is advantageous in terms of manufacturing efficiency.

[0029] 2 and 3, the inner adhesive portion 112 may be provided over the entire connecting portion 43. In Fig. 3, the first adhesive portion 110 is provided up to the edge (side surface) of the electromagnetic steel sheet 40 that forms the slot 44 at all positions when viewed from the stacking direction, but it is not necessary for it to be provided up to the edge at at least one of the two circumferential adhesive portions 111, the inner adhesive portion 112, and the outer adhesive portion 113, or at least at one location of the first adhesive portion 110.

[0030] The widths of the first adhesive portions 110, such as the width of the peripheral adhesive portion 111, the width of the inner adhesive portion 112, and the width of the outer adhesive portion 113, are not particularly limited and may be set appropriately from the viewpoint of preventing leakage of the cooling medium. Iron loss degradation may also be taken into consideration, and in this case, the widths of the adhesive portions are set appropriately taking both leakage prevention and iron loss degradation into consideration. Here, the width of the adhesive portion refers to the length in the direction perpendicular to the longitudinal direction (extension direction) of the adhesive portion when viewed from the stacking direction.

[0031] 2 and 3 (as well as FIG. 1 ), the first adhesive portions 110 are configured from the circumferential adhesive portions 111, the inner adhesive portions 112, and the outer adhesive portions 113, so that each slot 44 of the stator core 30 is surrounded without any gaps by the multiple first adhesive portions 110 and the multiple electromagnetic steel sheets 40 that are alternately arranged in the stacking direction. This makes it possible to prevent the cooling medium flowing through the slot 44 from leaking out of the slot 44 ( FIG. 3 ) or to keep the cooling medium in the vicinity of the slot 44 ( FIG. 2 ). This makes it possible to prevent the cooling medium from leaking out of the stator core 30.

[0032] 4 , the first adhesive portion 110 may have an inner annular adhesive portion 121 that is provided continuously in an annular shape around the tip ends of the plurality of teeth 42 that form the inner peripheral edge of the annular stator core 30 and the plurality of connecting portions 43, and an outer annular adhesive portion 122 that is provided continuously in an annular shape around the core back 41. The inner annular adhesive portion 121 and the outer annular adhesive portion 122 are each formed continuously without interruption. That is, when viewed from the stacking direction, the inner annular adhesive portion 121 and the outer annular adhesive portion 122 surround the plurality of slots 44.

[0033] In the embodiment shown in FIG. 4 , the outer ring adhesive portion 122 is formed in an annular (perfectly circular) shape in the central region of the annular core back 41. However, the present invention is not limited to this embodiment. For example, the outer ring adhesive portion 122 may be provided in an annular shape in a region closer to the inner edge 41 i or the outer edge 41 e of the core back 41 than to the central region of the core back 41. The closer the outer ring adhesive portion 122 is to the inner edge 41 i of the core back 41, the smaller the range of coolant leaking from the slots 44 to between the electromagnetic steel sheets 40 can be. The closer the outer ring adhesive portion 122 is to the outer edge 41 e of the core back 41, the farther the outer ring adhesive portion 122 is from the region where magnetic flux mainly flows during operation of the rotating electric machine (the radially inner region of the core back 41). This makes it possible to reduce deterioration of magnetic properties, such as iron loss, due to compressive stress (distortion) imparted to the electromagnetic steel sheets 40 by solidification of the adhesive. It should be noted that when compressive stress (elastic compressive stress) is applied to a steel sheet, iron loss increases, as described, for example, in a document by Yabumoto et al. (Nippon Steel Technical Report No. 378, pp. 51-54 (2003)).

[0034] In the embodiment shown in FIG. 4 , the inner annular adhesive portion 121 and the outer annular adhesive portion 122 each have a circular shape with a generally constant width. However, at least one of them may include at least a portion of a straight line, a wavy portion, a curved portion with a different curvature than the other portions, a portion of the first adhesive portion 110 having a different width than the other portions, or a portion of the first adhesive portion 110 being present on the tooth 42, or a combination thereof. The width of the first adhesive portion 110 refers to the length in a direction perpendicular to the longitudinal direction (extension direction) of the adhesive portion when viewed from the stacking direction. The widths of the inner annular adhesive portion 121 and the outer annular adhesive portion 122 are arbitrary. Furthermore, each of the inner annular adhesive portion 121 and the outer annular adhesive portion 122 may be composed of one or more annular adhesive portions spaced apart in the radial direction D. When the outer ring adhesive portion 122 includes a plurality of annular adhesive portions, the outer ring adhesive portion 122 may be configured by a plurality of annular adhesive portions provided at intervals in the radial direction D in at least a portion of the core back 41, such as the central region. The outer ring adhesive portion 122 may be provided over the entire surface of the core back 41. Furthermore, when the inner ring adhesive portion 121 includes a plurality of annular adhesive portions, the inner ring adhesive portion 121 may be configured by a plurality of annular adhesive portions provided at intervals in the radial direction D in the tip portions and connecting portions 43 of the teeth 42.

[0035] In this way, all slots 44 in the stator core 30 are surrounded by the first adhesive portion 110, which has an inner ring adhesive portion 121 and an outer ring adhesive portion 122, thereby preventing cooling medium from leaking out of the stator core 30 to the outside.

[0036] The first adhesive portion 110 has been described above using FIGS. 2 to 4. As described above, the first adhesive portion 110 surrounds each slot 44 of the stator core 30 individually (see FIGS. 1 to 3) or entirely (see FIG. 4). This prevents the coolant flowing through the slots 44 in the stator core 30 from leaking out of the area surrounded by the first adhesive portion 110. This prevents the coolant from leaking out of the stator core 30. From the viewpoint of ensuring the flow of magnetic flux, it is preferable to configure each slot 44 to be surrounded by a single first adhesive portion 110 as described above. However, from the viewpoint of simplifying the manufacturing process, it is also possible to configure adjacent slots 44 to be surrounded by a single first adhesive portion 110.

[0037] Next, details other than the configuration of the first adhesive portion 110 described above will be described. The first adhesive portion 110 may be formed by solidifying a first adhesive, whose adhesive strength varies depending on the pressure applied during bonding. The adhesive strength of this first adhesive varies depending on the pressure applied during bonding. For example, the higher the pressure applied during bonding, the higher the adhesive strength after solidification. The first adhesive may be applied to at least a portion of the surface of the stator core 30, such as the entire surface between adjacent electromagnetic steel sheets 40, or at least the periphery of a slot 44 ( FIGS. 2 and 3 ) or the area surrounding multiple slots 44 ( FIG. 4 ). The first adhesive portion 110 may be formed by applying a stronger pressure locally to only the area that will become the first adhesive portion 110 than to other areas. When the first adhesive is applied to the entire surface, an adhesive coating may be formed using the first adhesive. The adhesive that forms the adhesive coating may be a type of adhesive that hardens by heat treatment. Applying adhesive to targeted locations on each punched stator core one by one is time-consuming and prone to unevenness, but applying the adhesive in a coating form (film-like form) has the advantage of suppressing uneven application and making it easier to uniformize the stack thickness. As a result, adhesive portion 100 includes first adhesive portion 110 and other adhesive portions. Examples of types of adhesives that can be used as the first adhesive include thermosetting adhesives that use polymerization bonding, acrylic adhesives that cure at room temperature, anaerobic adhesives, instant adhesives, and elastomer-containing acrylic adhesives.

[0038] According to the above configuration, by locally and strongly bonding only the regions of adjacent electromagnetic steel sheets 40 where the first adhesive portions 110 are formed, the adjacent electromagnetic steel sheets are bonded by the first adhesive portions 110, and the regions where the first adhesive portions 110 are formed are bonded relatively more strongly than other regions (e.g., regions that become the second adhesive portions 120 described below). This allows the first adhesive portions 110 to contribute more to the fixing force between the electromagnetic steel sheets 40 than when a uniform adhesive strength is provided. Therefore, it is possible to ensure the fixing force required for the stator core even if the adhesive strength of the portions of the adhesive portion 100 other than the first adhesive portions 110 is weakened or the area of ​​those portions is reduced. Therefore, by weakening the adhesive strength of the regions other than the first adhesive portions 110, the adhesive strength of the regions where magnetic flux mainly flows during operation can be reduced, thereby reducing the impact of increased iron loss due to compressive stress applied to the electromagnetic steel sheets 40 by the adhesive portions 100. Therefore, it is possible to prevent the cooling medium from leaking from inside the slots 44 to the outside while suppressing deterioration of the characteristics of the stator 10 as a whole.

[0039] In addition, the compressive stress (residual compressive stress) remaining in the area where the first adhesive portion 110 is provided in the connecting portion 43 of the electromagnetic steel plate 40 may be greater than the compressive stress remaining in the area where the first adhesive portion 110 is provided in the part of the electromagnetic steel plate 40 other than the connecting portion 43.

[0040] The compressive stress remaining in the electromagnetic steel sheets 40 can be measured, for example, by the X-ray diffraction method described in Standard for X-Ray Stress Measurement (2002) = Iron and Steel = (JSMS-SD-5-02), Japan Society for Materials Science). When measuring the compressive stress remaining in the electromagnetic steel sheets 40 using the X-ray diffraction method, the stator 10 is divided in the lamination direction at the adhesive joint 100 between the electromagnetic steel sheets 40. The method for dividing the stator 10 in the lamination direction is not particularly limited, but may involve inserting a tool into the gap between the electromagnetic steel sheets 40 (the adhesive joint 100) and applying force from the tool as a starting point to split the stator 10 into two. Alternatively, the adhesive joint 100 may be cut to split the stator 10 into two. In this way, the adhesive joints 100 between the electromagnetic steel sheets 40 are exposed. The presence or absence of the adhesive joints 100 can be confirmed by visually inspecting the sampled electromagnetic steel sheets 40, but the compressive stress remaining in the electromagnetic steel sheets 40 is measured by preparing samples suitable for the above-mentioned X-ray diffraction method from the sampled electromagnetic steel sheets 40. When using the X-ray diffraction method, it is desirable to remove the adhesive joints 100, because if the adhesive joints 100 are present on the surface of the electromagnetic steel sheets 40, X-rays will not penetrate to the desired depth into the electromagnetic steel sheets 40. On the other hand, when visually inspecting the application state (shape, etc.) of the adhesive joints 100, it is better if traces of the adhesive joints 100 remain.

[0041] For example, in the case where the first adhesive portion 110 is composed of a peripheral adhesive portion 111, an inner adhesive portion 112, and an outer adhesive portion 113 as shown in Figures 2 and 3, the compressive stress remaining in the region of the connecting portion 43 where the inner adhesive portion 112 is provided may be greater than at least one of the compressive stress remaining in the region of the tooth 42 where the peripheral adhesive portion 111 is provided or the region of the core back 41 where the outer adhesive portion 113 is provided.

[0042] Furthermore, in the case where the first adhesive portion 110 is composed of an inner ring adhesive portion 121 and an outer ring adhesive portion 122 as shown in Figure 4, the compressive stress remaining in the area where the inner ring adhesive portion 121 is provided in the connecting portion 43 may be greater than the compressive stress remaining in either or both of the area where the inner ring adhesive portion 121 is provided at the tip of the tooth 42 or the area where the outer ring adhesive portion 122 is provided in the core back 41.

[0043] If the tips of adjacent teeth 42 are connected by the connecting portion 43, magnetic flux will be able to flow through the connecting portion 43 during operation of the rotating electric machine 1, which is undesirable from the perspective of performance of the rotating electric machine 1. Therefore, in this embodiment, by taking advantage of the fact that the magnetic properties of the electromagnetic steel sheets 40 deteriorate as the adhesive solidifies, high pressure is applied to solidify the first adhesive so that the connecting portion 43 exhibits a stronger adhesive strength (adhesive force) than is necessary for adhesive fixation. This makes it possible to actively increase the iron loss of the connecting portion 43 and make it more difficult for magnetic flux to flow through the connecting portion 43. Therefore, it is possible to suppress deterioration of motor characteristics due to magnetic flux flowing through the connecting portion 43.

[0044] Such a distribution of residual compressive stress in the first adhesive portion 110 may be formed, for example, by using two or more different types of adhesive and applying uniform pressure to the surfaces of the stacked electromagnetic steel sheets when joining the electromagnetic steel sheets 40 together. In this case, among the different adhesives, for example, the adhesive that solidifies to become the first adhesive portion 110 may be referred to as the first adhesive, and the adhesive that solidifies to become the second adhesive portion 120 may be referred to as the second adhesive. Alternatively, the distribution of residual compressive stress may be achieved by using the above-mentioned first adhesive to form the first adhesive portion 110 and applying pressure with different pressure distributions during joining. Here, when manufacturing the stator core 30, electromagnetic steel sheets 40 to which the adhesive that will become the adhesive portion 100 has been applied are stacked, and the stacked electromagnetic steel sheets 40 are joined by applying pressure in the stacking direction. The pressure is applied, for example, by a pressure device that applies pressure to the stator core 30 via a pressure jig that presses the stator core 30. The pressure distribution on the surface of the electromagnetic steel sheets 40 during bonding can be adjusted by forming irregularities on the pressure jig. For example, a pressure jig that can apply a locally higher pressure by making the portion of the first adhesive portion 110 that forms the connecting portion 43 protrude in the pressure application direction more than other portions may be used. By using such a pressure jig, the pressure distribution on the surface of the electromagnetic steel sheets 40 during bonding can be set as desired. An example of a pressure jig will be described later.

[0045] According to the above configuration, the adhesive strength of the portion of the first adhesive portion 110 corresponding to the connecting portion 43 is intentionally made greater than the adhesive strength of the portions corresponding to the core back 41 and the teeth 42. This increases the iron loss of the connecting portion 43, making it difficult for magnetic flux to flow in the connecting portion 43, thereby suppressing deterioration of the motor characteristics.

[0046] 1 to 4 may be fixed by adhesive portions 100 including the first adhesive portions 110 and second adhesive portions 120 provided at positions different from the first adhesive portions 110. In this case, the second adhesive portions 120 may be provided in at least a portion of the area on the surface of each electromagnetic steel sheet 40 where the first adhesive portions 110 are not provided, or may be provided in the entire area. In particular, when the entire surface of the electromagnetic steel sheet 40 is covered by the adhesive portions 100 including the first adhesive portions 110 and the second adhesive portions 120, the adhesive portions 100 may be formed by solidifying the first adhesive under the pressure distribution described above.

[0047] When the first adhesive portion 110 and the second adhesive portion 120 cover the adhesive portion 100 between adjacent electromagnetic steel sheets 40 in the stacking direction, the compressive stress remaining in the region of the electromagnetic steel sheet 40 where the first adhesive portion 110 is provided may be greater than the compressive stress remaining in the region of the electromagnetic steel sheet 40 where the second adhesive portion 120 is provided. The latter distribution of residual compressive stress may be formed, for example, by using two or more different types of adhesive and applying uniform pressure to the surfaces of the stacked electromagnetic steel sheets. Alternatively, the adhesives forming the first adhesive portion 110 and the second adhesive portion 120 may be the same type for the electromagnetic steel sheet 40, and the first adhesive portion 110 and the second adhesive portion 120 may be formed using the above-mentioned first adhesive and pressure jig. Furthermore, the compressive stress remaining in at least the region of the connecting portion 43 among the regions in which the first adhesive portion 110 is provided in the electromagnetic steel plate 40 may be greater than the compressive stress remaining in the region in which the second adhesive portion 120 is provided in the electromagnetic steel plate 40.

[0048] 1 to 4, when all of the surface portions of the electromagnetic steel sheets 40 that do not have first adhesive portions 110 are to be second adhesive portions 120, the above-mentioned first adhesive is applied between all of the adjacent electromagnetic steel sheets, and then the first adhesive is solidified by applying pressure using a pressure jig with projections and recesses so that the areas corresponding to the first adhesive portions 110 become convex portions and the areas corresponding to the second adhesive portions 120 become concave portions. In this way, an adhesive portion 100 is formed in which all of the areas that do not have first adhesive portions 110 in FIGS. 1 to 4 become second adhesive portions 120.

[0049] According to the above configuration, the stator core 30 is bonded and fixed by the adhesive portion 100 including the first adhesive portion 110 and the second adhesive portion 120. This makes it possible to firmly fix the stator core 30 while preventing the coolant flowing through the slots 44 from leaking out of the stator core 30. Furthermore, if the second adhesive portion 120 is provided in all areas between the electromagnetic steel sheets 40 where there are no first adhesive portions 110, the entire surfaces of the electromagnetic steel sheets 40 are bonded by the first adhesive portion 110 and the second adhesive portion 120, thereby further improving the ability to prevent coolant leakage and the fixing strength of the stator core 30.

[0050] However, the present invention is not limited to the above-described embodiment. The adhesive portion 100 may be only the first adhesive portion 110, without including the second adhesive portion 120. For example, the first adhesive portion 110 may be formed by applying the above-described first adhesive only to the portion where the first adhesive portion 110 is to be formed and then solidifying it. Furthermore, instead of the second adhesive portion 120, the multiple electromagnetic steel sheets 40 that constitute the stator core 30 may be fixed by other fixing means. Examples of other fixing means include crimping and welding.

[0051] (Pressing Jig) A pressing jig 200 that can be used in manufacturing the stator core 30 according to the above-described embodiment will now be described. Fig. 5 is a schematic diagram showing an example of using the pressing jig 200. The pressing jig 200 is used when pressure needs to be applied for bonding. For example, it is mainly used when an adhesive coating (adhesive film) is provided on the electromagnetic steel sheets 40.

[0052] The pressing jig 200 is a jig that presses a stack of multiple electromagnetic steel sheets 40 that make up the stator core 30, at least some of which are stacked with adhesive sandwiched between them (hereinafter referred to as core portion P), for adhesive fixation during the manufacture of the stator core 30. As shown in Fig. 5 , the pressing jig 200 includes a first member 210 having an uneven pressing surface 211 that presses the core portion P while contacting it. The core portion P is bonded by applying pressure to it via the first member 210 using a pressing unit 201 of the pressing device. The core portion P may be heated to a predetermined temperature before pressure is applied.

[0053] More specifically, on the pressing surface 211 of the first member 210, a position (region) corresponding to the region where the first adhesive portion 110 is formed protrudes more than a position (region) corresponding to the region where the second adhesive portion 120 is formed in the stacking direction of the stator core 30. In other words, the position corresponding to the first adhesive portion 110 has a convex shape in the stacking direction of the stator core 30, and the position corresponding to the second adhesive portion 120 has a concave shape in the stacking direction of the stator core 30. In this way, the pressing surface 211 has a first pressing portion 211A (convex portion) configured to press relatively strongly at the position corresponding to the first adhesive portion 110, and a second pressing portion 211B (concave portion) configured to press relatively weakly at the position corresponding to the second adhesive portion 120.

[0054] In short, the pressing surface 211 of the pressing jig 200 has projections and recesses so that, during bonding, the pressure applied to desired areas of the core portion P is higher than that applied to other areas. The shape of the projections and recesses on the pressing surface 211 in a plan view of the stator core 30 in the stacking direction is designed according to the shape and position of the first adhesive portion 110. As a result, the areas corresponding to the projections are subjected to higher pressure during pressing than the areas corresponding to the recesses. Therefore, if the adhesive used to bond and fix the stator core 30 is of a type that exhibits adhesive strength according to the magnitude of pressure applied during bonding, the first adhesive portion 110 and the second adhesive portion 120 can be formed by applying pressure to the core portion P in one go.

[0055] In the embodiment shown in FIG. 5 , the pressing jig 200 (first member 210) is a plate-like member with concaves and convexes formed thereon, such as a mold in which concaves and convexes are formed in the thickness direction of a metal plate having a predetermined thickness. Furthermore, when pressed by the pressing unit 201, the first pressing unit 211A of the first member 210 presses a predetermined portion of the electromagnetic steel sheet 40, and the second pressing unit 211B presses an area other than the predetermined portion. The predetermined portion includes at least a position corresponding to the connecting portion 43, but may also include a position corresponding to the entire first adhesive portion 110. On the pressing surface 211, a predetermined portion protrudes beyond at least a portion of its surroundings, thereby forming a convex portion where the predetermined portion protrudes, and at least a portion of the periphery of the convex portion corresponds to a concave portion.

[0056] The pressing surface 211 also includes a tapered portion 212 that connects the first pressing portion 211A and the second pressing portion 211B. That is, the first pressing portion 211A and the second pressing portion 211B are smoothly connected and are formed so that the pressure applied thereto changes gradually. As a configuration in which the pressure applied thereto changes gradually, for example, the tapered portion 212 may be gradually inclined at a constant rate or may change in a quadratic curve.

[0057] 5, a first member 210 is disposed above the core portion P with its pressing surface 211 facing downward. In addition, the core portion P is supported from below by being disposed on the upper surface of a second member 220 fixedly disposed below the core portion P, and the pressing portion 201 of the pressing device presses the first member 210 in the direction of arrow F (downward in the stacking direction), thereby applying pressure to the core portion P and adhesively fixing it.

[0058] However, the present invention is not limited to the above-described embodiment. For example, the first member 210 may be disposed below and the second member 220 may be disposed above. Furthermore, in addition to the first member 210, the support surface of the core portion P of the second member 220 may also be formed with concaves and convexes that match the concaves and convexes of the pressing surface 211 of the first member 210. Furthermore, the first pressing portion 211A and the second pressing portion 211B of the first member 210 do not have to include the tapered portion 212, and may be connected by, for example, a single staircase-like step portion.

[0059] 5 is a schematic representation of the shape of the pressing jig 200 for ease of understanding, and the dimensions of the actual pressing jig 200 may differ. For example, in the view indicated by the arrow in FIG. 5 (side view of the stator core 30), a difference H (μm) in the unevenness of the pressing surface 211 is provided. The difference H may be determined based on the relationship between the pressure conditions of the adhesive determined in advance by experiment, calculation, or the like, and the improvement in strength of the electromagnetic steel sheet 40 due to the provision of the first adhesive portion 110.

[0060] According to the above-described pressing jig 200, the unevenness formed on the pressing surface 211 makes it possible to create a pressure distribution on the surface of the electromagnetic steel sheet 40 with a single application of pressure. Therefore, when adhesively fixing the electromagnetic steel sheet 40, a higher pressure can be applied to the area of ​​the electromagnetic steel sheet 40 where the first adhesive portion 110 is to be formed than to the area where the second adhesive portion 120 is to be formed with a single application of pressure. Therefore, the first adhesive portion 110 and the second adhesive portion 120 can be formed efficiently, thereby reducing the manufacturing cost of the stator core 30.

[0061] (Rotating Electric Machine) The rotating electric machine according to this embodiment includes the stator core according to the above-described embodiment. Since the rotating electric machine according to this embodiment includes the stator 10 described above, leakage of the cooling medium from the stator core 30 is prevented, and a structure or device for recovering the leaked cooling medium is not required. Note that the rotating electric machine refers to a motor or a generator. The motor is not particularly limited, and the motor type may be, for example, an IPM (Interior Permanent Magnet) motor, an IM (Induction Motor), or an EESM (Electrically Excited Synchronous Motor). Furthermore, the rotating electric machine may be an outer rotor motor.

[0062] The stator core according to the present invention can prevent the cooling medium flowing through the slots from leaking from the stator core. Furthermore, since the rotating electric machine according to the present invention includes the stator described above, leakage of the cooling medium from the stator core is prevented, and a structure or device for recovering the leaked cooling medium is not required. Furthermore, by using the pressing jig according to the present invention, a bonding portion having a first bonding portion and a second bonding portion can be efficiently formed. Therefore, the present invention is extremely useful industrially.

[0063] REFERENCE SIGNS LIST 1 Rotating electric machine 10 Stator 20 Rotor 30 Stator core 40 Electromagnetic steel sheet 41 Core back 41e Outer edge 41i Inner edge 42 Teeth 43 Connecting portion 44 Slot 44a Slot peripheral side edge 44b Slot inner edge 44c Slot outer edge 50 Coil 100 Bonding portion 110 First bonding portion 111 Peripheral side bonding portion 112 Inner bonding portion 113 Outer bonding portion 120 Second bonding portion 121 Inner ring bonding portion 122 Outer ring bonding portion 200 Pressing jig 201 Pressing portion 210 First member 211 Pressing surface 211A First pressing portion 211B Second pressing portion 212 Tapered portion 220 Second member

Claims

1. A stator core comprising: a plurality of stacked electromagnetic steel sheets; and adhesive portions respectively arranged between adjacent electromagnetic steel sheets in the stacking direction, wherein each of the electromagnetic steel sheets includes an annular core back, a plurality of teeth spaced circumferentially and protruding radially from the core back, and a connecting portion connecting the tips of adjacent teeth, and wherein the adhesive portion includes a first adhesive portion surrounding a space formed by the core backs of the plurality of electromagnetic steel sheets, the adjacent teeth, and the connecting portion.

2. A stator core as described in claim 1, characterized in that the first adhesive portion comprises: a circumferential adhesive portion provided on each of the adjacent teeth; an inner adhesive portion provided on the connecting portion and connecting the radially inner sides of the circumferential adhesive portions of each of the adjacent teeth; and an outer adhesive portion provided on the core back and connecting the radially outer sides of the circumferential adhesive portions of each of the adjacent teeth.

3. A stator core as described in claim 2, characterized in that the peripheral adhesive portion is provided at the end closest to the space of each of the adjacent teeth, the inner adhesive portion is provided at least at the radially outer end of the connecting portion, and the outer adhesive portion is provided at the radially inner end of the core back.

4. A stator core as described in claim 2, characterized in that the compressive stress remaining in the region of the connecting portion where the inner adhesive portion is provided is greater than at least one of the compressive stress remaining in the region of the tooth where the circumferential adhesive portion is provided and the region of the core back where the outer adhesive portion is provided.

5. A stator core as described in claim 1, characterized in that the first adhesive portion has an inner ring adhesive portion provided in a ring shape around the tip ends of the plurality of teeth and the plurality of connecting portions, and an outer ring adhesive portion provided in a ring shape around the core back.

6. A stator core as described in claim 5, characterized in that the compressive stress remaining in the region of the connecting portion where the inner ring adhesive portion is provided is greater than the compressive stress remaining in at least one of the region of the tip of the tooth where the inner ring adhesive portion is provided and the region of the core back where the outer ring adhesive portion is provided.

7. A stator core according to any one of claims 1 to 6, characterized in that the adhesive portion further includes a second adhesive portion provided at a position different from the first adhesive portion.

8. A stator core as described in claim 7, characterized in that the first adhesive portion is a solidified first adhesive that exerts adhesive strength according to the pressure applied during bonding, and the compressive stress remaining in the area of ​​the connecting portion where the first adhesive portion is provided is greater than the compressive stress remaining in the area of ​​the electromagnetic steel plate where the second adhesive portion is provided.

9. A stator core according to claim 7, characterized in that the second adhesive portions are provided in all areas between the electromagnetic steel sheets where the first adhesive portions are not present.

10. A rotating electric machine comprising a stator core according to any one of claims 1 to 6.

11. A rotating electric machine comprising the stator core according to claim 7.

12. A pressing jig used in the manufacture of a stator core comprising a plurality of stacked electromagnetic steel plates and adhesive portions respectively arranged between adjacent electromagnetic steel plates in the stacking direction, wherein the stator core has a plurality of teeth and connecting portions connecting adjacent teeth, and the pressing jig comprises a member having irregularities on its pressing surface, and the pressing surface of the member protrudes at least at a position corresponding to the connecting portion.

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