Stator core, rotating electrical machine, and method for manufacturing stator

Abstract

The stator core (30) comprises a core sheet (30S) having a plurality of teeth (31) disposed in the longitudinal direction (N) on one side (H1) in the width direction (H), and a yoke (32) on the other side (H2) in the width direction (H). The yoke (32) has a plurality of crescent-shaped openings (35) each having an arc whose apex is located on the other side (H2) and being disposed at preset intervals in the longitudinal direction (N), the yoke (32) having an end face on the other side (H2), the end face having a plurality of protrusions (39) each being located at a corresponding one of the openings (35) and protruding in the other side (H2) by a second width (W2) corresponding to a first width (W1) of the openings (35) in the width direction.

Description

Stator core, rotating electric machine, and method for manufacturing stator

[0001] The present disclosure relates to a stator core, a rotating electric machine, and a method for manufacturing a stator.

[0002] Conventionally, stator cores for rotating electric machines have included strip cores, which are made by stamping electromagnetic steel sheets into strip, ring, fan, or other shapes using press forming, and then stacking a plurality of these stamped strip-shaped electromagnetic steel sheets into a cylindrical shape; wound cores, which are made by spirally winding strip-shaped electromagnetic steel sheets while press-forming them into a teeth shape, and then stacking them into a cylindrical shape; and so on.

[0003] In recent years, the adoption of wound cores, which have a high material yield, has become more common. A typical wound core manufacturing method involves forming multiple teeth on one widthwise side of a strip-shaped electromagnetic steel sheet (hereinafter, the sheet after forming the teeth is referred to as the core sheet). The outer periphery of the core sheet on the other widthwise side (hereinafter, referred to as the yoke portion) is then rolled using a rolling mill or other rolling method to reduce the thickness toward the ends, while increasing the periphery of the outer periphery, resulting in spiral winding. However, in this method of manufacturing a stator core, the electromagnetic steel sheet is rolled (flat-formed). Therefore, if the thickness of the electromagnetic steel sheet varies in the longitudinal direction, rolling the thicker portions (curved forming) results in a larger elongation, while rolling the thinner portions results in a smaller elongation. This creates a problem of uneven winding diameter in the stacking direction when the core sheet is spirally wound. To address this problem, the following stator core manufacturing method has been disclosed.

[0004] That is, a conventional method for manufacturing a stator core includes a punching process in which a core sheet consisting of a linear yoke portion and a plurality of teeth protruding from one side of the width of the yoke portion is punched out of a sheet of metal, and a forming process in which the yoke portion of the core sheet is bent in the width direction by rolling it so that the longitudinal extension increases from one end of the width direction to the other end, and then laminated while being wound spirally.The method further includes a pre-forming process prior to the forming process in which a recess that is recessed in the thickness direction is formed in the yoke portion of the core sheet or in a portion of the sheet of metal corresponding to the yoke portion, and in the forming process, the rolling is performed including the portion in which the recess is formed (see, for example, Patent Document 1).

[0005] Patent No. 6060805

[0006] In the conventional stator core manufacturing method described above, it has been proposed to form a recess in the thickness direction of the core sheet at a location corresponding to the yoke portion so that the thickness of the core sheet does not affect the forming accuracy. This makes it easier for the components constituting the core sheet to flow in the width direction during rolling, and makes the change in the amount of longitudinal elongation at the rolled location uniform.

[0007] However, in this manufacturing method of a stator core, the outer periphery of the core sheet is rolled, resulting in a thin sheet thickness at the outer periphery. As a result, in a stator core in which the core sheet is spirally wound and stacked, gaps form between the outer peripheries of adjacent core sheets in the stacking direction. The presence of these gaps creates a thin, vulnerable outer edge that is vulnerable to external forces, leading to problems such as vibration, deformation, or damage during subsequent transport processes and actual operation. Another problem is that the thin core sheet significantly reduces the effective magnetic path area, resulting in reduced magnetic performance and reduced output from the rotating electric machine.

[0008] The present disclosure discloses technology for solving the above-mentioned problems, and aims to provide a stator core that ensures high magnetic performance while preventing deformation, damage, etc. to ensure reliability, a highly reliable and efficient rotating electric machine, and a stator manufacturing method that can manufacture a stator that ensures high magnetic performance while preventing deformation, damage, etc. to ensure reliability.

[0009] The stator core of the present disclosure is a stator core formed by laminating annular core sheets each formed by bending a core sheet made of electromagnetic steel plate into a ring shape with one widthwise side facing inward, wherein the core sheet includes, on one side in the widthwise direction, a plurality of teeth portions arranged at predetermined intervals in the longitudinal direction and constituting magnetic poles, and a yoke portion connecting the teeth portions on the other side in the widthwise direction, wherein the yoke portion in the core sheet includes a plurality of crescent-shaped openings arranged at predetermined intervals in the longitudinal direction with the apex of the arc constituting the opening positioned on the other side, and a protrusion protruding to the other side by a second width corresponding to a first width of the opening in the widthwise direction is formed on an end face of the yoke portion located on the other side of each of the openings in the core sheet. Also, the rotating electric machine of the present disclosure includes a stator using the stator core configured as described above, and a rotor arranged coaxially with the stator. Furthermore, the method for manufacturing a stator disclosed herein is a method for manufacturing a stator using a stator core configured as described above, which includes a U-phase winding as a phase winding wound continuously around each of the teeth corresponding to the U-phase, a V-phase winding as a phase winding wound continuously around each of the teeth corresponding to the V-phase, and a W-phase winding as a phase winding wound continuously around each of the teeth corresponding to the W-phase, and after performing an attachment process in which the U-phase winding, the V-phase winding, and the W-phase winding are attached to the teeth of the corresponding phases in a laminated core sheet formed by stacking a plurality of the core sheets, the laminated core sheet is bent into an annular shape to form a stator formed by stacking the annular core sheets.

[0010] The stator core of the present disclosure can provide a stator core that ensures high magnetic performance while preventing deformation, damage, and the like and ensuring reliability. The rotating electric machine of the present disclosure can provide a highly reliable and efficient rotating electric machine. The stator manufacturing method of the present disclosure can provide a stator manufacturing method that can manufacture a stator that ensures high magnetic performance while preventing deformation, damage, and the like and ensuring reliability.

[0011] FIG. 1 is a cross-sectional view showing a schematic configuration of a core sheet that constitutes the stator core of a stator according to embodiment 1. FIG. 1 is a cross-sectional view showing a schematic configuration of a stator according to embodiment 1. FIG. 2 is a cross-sectional schematic view showing a configuration of a rotating electric machine according to embodiment 1. FIG. 2 is a cross-sectional view showing another example of a schematic configuration of a core sheet that constitutes the stator core of a stator according to embodiment 1. FIG. 3 is a cross-sectional view showing another example of a schematic configuration of a stator according to embodiment 1. FIG. 4 is a cross-sectional view showing another example of a schematic configuration of a core sheet that constitutes the stator core of a stator according to embodiment 1. FIG. 5 is a cross-sectional view showing another example of a schematic configuration of a stator according to embodiment 1. FIG. 6 is a cross-sectional view showing another example of a schematic configuration of a stator according to embodiment 1. FIG. 7 is a conceptual diagram showing a magnetic flux flow in the stator according to embodiment 1. FIG. 8 is a conceptual diagram showing a heat flow in the stator according to embodiment 1. FIG. 9 is a cross-sectional view showing another example of a schematic configuration of a core sheet that constitutes the stator core of a stator according to embodiment 1. FIG. 10 is a cross-sectional view showing another example of a schematic configuration of a stator according to embodiment 1. Fig. 1 is a cross-sectional view showing another example of the configuration of an opening in a core sheet according to embodiment 1. Fig. 2 is a cross-sectional view showing another example of the configuration of a stator according to embodiment 1. Fig. 3 is a cross-sectional view showing another example of the configuration of an opening in a core sheet according to embodiment 1. Fig. 4 is a cross-sectional view showing another example of the configuration of an opening in a core sheet according to embodiment 1. Fig. 5 is a cross-sectional view showing another example of the configuration of an opening in a core sheet according to embodiment 1. Fig. 6 is a conceptual diagram showing another example of the configuration of a stator according to embodiment 1.

[0012] Embodiment 1. The stator core 30 of the stator 50, the rotating electric machine 100, and the manufacturing method of the stator 50 according to an embodiment of the present disclosure will be described below with reference to the drawings. Note that the same or equivalent members and parts will be described with the same reference numerals in each drawing. FIG. 1 is a cross-sectional view showing the general configuration of a core sheet 30S constituting the stator core 30 of the stator 50 according to embodiment 1. FIG. 2 is a cross-sectional view showing the general configuration of the stator 50 according to embodiment 1. FIG. 3 is a schematic cross-sectional view showing the configuration of the rotating electric machine 100 according to embodiment 1. Note that the longitudinal direction and width direction of the strip-shaped core sheet 30S will be referred to as the longitudinal direction N and width direction H, respectively. Furthermore, the directions in the annular rotating electric machine 100 will be referred to as the circumferential direction C, the radial direction X, and the axial direction Z. Furthermore, a plane perpendicular to the axial direction Z will sometimes be referred to as the XY plane.

[0013] First, the configuration of the rotating electric machine 100 will be described with reference to Figure 3. The rotating electric machine 100 includes a cylindrical housing 70, a stator 50 housed therein, and a rotor 60 disposed opposite the stator 50. The housing 70 has a cylindrical frame 71 with a bottom and an end plate 72 that closes an opening of the frame 71. The stator 50 is fixed to the frame 71 in a state of being fitted inside the frame 71 in the radial direction X. The rotor 60 is rotatably supported inside the stator 50 in the radial direction X by a main shaft 74 provided via a bearing 73 at the center of the end plate 72 of the frame 71.

[0014] 3 shows a typical example of the rotating electric machine 100, and the rotating electric machine 100 of the present disclosure may have a sealed housing 70 as shown in FIG. 3 , or an open housing in which the stator 50 and the rotor 60 are in contact with the surrounding space. The rotating electric machine 100 may also have a housing 70 composed of three or more components. For example, the rotating electric machine 100 may be provided with various sensors, such as a rotation sensor and a temperature sensor, and auxiliary devices, such as a cooler and a pump. Furthermore, the rotating electric machine 100 may be integrated with a belt / chain mechanism, a reduction / drive transmission mechanism, such as a gearbox, or a power converter / control device. The rotating electric machine refers to a device that converts electric power into rotational force and transmits the rotational force to the outside.

[0015] The stator core 30 used in the rotating electric machine 100 shown in Figure 3 is constructed by stacking annular core sheets 30R formed by spirally winding a strip-shaped core sheet 30S shown in Figure 1, which will be described below, in the axial direction Z.

[0016] 1 is made of a strip-shaped electromagnetic steel sheet formed by press molding. The core sheet 30S has, on one side H1 in the width direction H, a plurality of teeth 31 arranged at set intervals in the longitudinal direction N to form magnetic poles, and, on the other side H2 in the width direction H, a yoke 32 connecting these teeth 31.

[0017] Crescent-shaped openings 35 are provided in the yoke portion 32 and are arranged at predetermined intervals in the longitudinal direction N. Each crescent-shaped opening 35 has an opening region surrounded by a first arc Arc1, in which a vertex P1 of the outer periphery of the arc is located on the other side H2 in the width direction H, and a second arc Arc2, in which a vertex P2 of the outer periphery of the arc is located on one side H1 in the width direction H of the first arc Arc1. In this way, openings 35 are arranged with the vertex side of the arc constituting the crescent-shaped opening located on the outer periphery of the yoke portion 32.

[0018] 1, the openings 35 are provided on a first extension line T1 extending from a first center line at the center of each slot SL in the width direction H. In this way, the number of openings 35 provided for each slot SL is equal to the number of magnetic poles formed by the teeth 31.

[0019] Here, a protrusion 39 is formed on the end face of the yoke portion 32 located on the other side H2 in the width direction H of each opening 35, protruding toward the other side H2 by a second width W2, the length of which corresponds to the first width W1 in the width direction H of the opening 35. In this embodiment, the second width W2 of the protrusion 39 at each position in the longitudinal direction N is configured to be the same length as the first width W1 of the opening 35 at each position in the longitudinal direction N, including a set margin.

[0020] Note that the second width W2 at each position in the longitudinal direction N of the protrusion 39 is not limited to being exactly the same length as the first width W1 at each position in the longitudinal direction N of the opening 35. Since the opening 35 has a crescent shape in which the width at both ends in the longitudinal direction N becomes smaller, the second width W2 of the protrusion 39 may be configured accordingly so that the width at both ends in the longitudinal direction N becomes gradually smaller than that at the center.

[0021] Next, an annular core sheet 30R formed using the core sheet 30S configured as described above will be described with reference to Fig. 2. The annular core sheet 30R is formed by bending the core sheet 30S shown in Fig. 1 into an annular shape as shown in Fig. 2 so that the tooth portion 31 side is on the inner peripheral side.

[0022] In the process of bending the core sheet 30S, when the outer peripheral surface side of the yoke portion 32 is pulled in the circumferential direction C, the protruding portion 39 is stretched in the circumferential direction C while its curvature decreases in the XY plane perpendicular to the axial direction Z. The second width W2 of the stretched protruding portion 39 in the width direction H gradually decreases. Finally, the outer peripheral surface of the protruding portion 39 becomes a curved surface identical to a circle having a radius equal to an intersection point P3 where the periphery of the protruding portion 39 intersects with the outer peripheral surface 32B between the protruding portions 39 shown in FIG. 1 , constituting the outer peripheral surface of the annular core sheet 30R.

[0023] Furthermore, at this time, the inner wall 35IN1 on one side H1 of the opening 35 in the width direction H and the inner wall 35IN2 on the other side H2 thereof approach each other, forming a slit 35S extending in the circumferential direction C as shown in FIG. 2 . In this manner, the first width W1 of the opening 35 in the core sheet 30S is adjusted so that the inner walls on both sides of the opening 35 in the width direction H form opposing slits 35S within a first distance set in the radial direction X in the formed annular core sheet 30R. Preferably, the first width W1 of the opening 35 is greater than or equal to the second width W2 of the protrusion 39. Note that the set first distance, which is the width of the slit 35S, may be set to zero, for example, when it is desired to bring the opposing inner walls 35IN1 and 35IN2 in contact with each other in the width direction H.

[0024] In this way, in forming the annular core sheet 30R, the protruding portion 39 protruding in the width direction H is stretched, while the opening 35 having a first width W1 in the longitudinal direction equal to the second width W2 of the protruding portion 39 is closed, thereby forming the core sheet 30S into an annular shape while suppressing changes in the plate thickness.

[0025] Here, the outer peripheral surface 32B between the protruding portions 39 of the yoke portion 32 shown in FIG. 1 is configured to have the following shape. As shown in FIG. 1, a circle is assumed whose radius is the axial center O of the annular core sheet 30R and the intersection point P3 where the periphery of the protruding portion 39 intersects with the outer peripheral surface 32B. The outer peripheral surface 32B is then formed into a curved surface with the same arc as this circle. In other words, the arc of the assumed circle corresponds to the shape of the outer peripheral surface of the cylindrical stator core 30. By thus matching the outer peripheral surface 32B between the protruding portions 39 of the core sheet 30S to the shape of the outer peripheral surface of the stator core 30, the circularity of the stator core 30 can be ensured when it is formed.

[0026] This is because, during the process of curving the core sheet 30S, the protrusions 39 absorb the tensile stress on the radially outer side of the yoke portion 32, thereby suppressing changes in the shape of the outer surface 32B between the protrusions 39, thereby ensuring the circularity of the formed stator core 30.

[0027] Furthermore, the tooth portions 31 are configured so that the width in the longitudinal direction N narrows from the other side H2 toward the one side H1 in the width direction H. As a result, when the core sheet 30S is formed into an annular shape so that the tip ends of the tooth portions 31 approach each other to form the annular core sheet 30R, the desired shape of the slot SL and its opening width can be obtained in the annular core sheet 30R.

[0028] In this way, annular core sheets 30R formed by spirally winding strip-shaped core sheets 30S are stacked in the axial direction Z to form the stator core 30. Then, windings 40 are wound around the teeth 31 of the stator core 30 by distributed winding, and the windings 40 are housed in the slots SL to form the stator 50.

[0029] Here, the rotating electric machine 100 has a stator core 30 press-fitted into a frame 70. Because the temperature of the rotating electric machine 100 varies between minus 40 degrees Celsius and several hundred degrees Celsius, the difference in linear expansion between the frame 70 material (aluminum, etc.) and the stator core 30 material causes the interference-fit fixing pressure to change. If the fixing pressure is insufficient, for example, if a gap occurs, the stator core 30 cannot be fixed, resulting in rotation of the stator core 30. In this disclosure, the stator core 30 is formed cylindrically centered on the axial center O. However, each protrusion 39 springs back slightly during molding and expands radially outward (the width of the slit 35S is greater than 0). Therefore, the stator core 30 has a cylindrical surface shape with multiple small protrusions 39. The spring action due to elastic deformation of these protrusions 39 suppresses changes in the fixing pressure between the frame 70 and the stator core 30, preventing rotation of the stator core 30.

[0030] Stator cores 30 having different configurations from those described above will now be described. Fig. 4 is a cross-sectional view showing another example of the schematic configuration of core sheet 30S constituting stator core 30 of stator 50 according to embodiment 1. Fig. 5 is a cross-sectional view showing another example of the schematic configuration of stator 50 according to embodiment 1.

[0031] 4, a plurality of openings 35 are arranged side by side in the width direction H. The plurality of openings 35 arranged in this manner for each slot SL, that is, the same number of openings 35 as the number of magnetic poles constituting the teeth portion 31, are referred to as an opening group 35G.

[0032] The openings 35 constituting each opening group 35G are arranged on a first extension line T1 extending from the first center line of the slot SL. The positions in the width direction H of each opening 35 constituting each opening group 35G are the same as the positions in the width direction H of each opening 35 constituting an adjacent opening group 35G.

[0033] Here, the second width W2 at each position in the longitudinal direction N of the protruding portion 39 is configured to be approximately equal to the sum of the first widths W1A, W1B of each opening 35 located on one side H1 of the protruding portion 39 at each position in the longitudinal direction N for each opening 35. In other words, the second width W2≦first width W1A+first width W1B. With this configuration, the protruding portion 39 having the second width W2 corresponding to the first widths W1A, W1B of the openings 35 is stretched when the core sheet 30S is bent, and the core sheet 30S is bent into an annular shape while suppressing changes in the sheet thickness.

[0034] In the stator 50 configured in this manner, the slits 35S are arranged on first extension lines T1 that extend radially outward from a first center line at the center of the slot SL in the circumferential direction C.

[0035] The flow of magnetic flux and the flow of heat in the stator 50 configured in this manner will be described with reference to FIGS. 6 and 7 . FIG. 6 is a conceptual diagram showing the flow of magnetic flux in the stator 50 according to the first embodiment. FIG. 7 is a conceptual diagram showing the flow of heat in the stator 50 according to the first embodiment. In this way, by configuring the stator 50 so that no slits 35S are provided on the radially outer side of the tooth portions 31, no cut portions of the core sheet 30S are provided in the path from the tooth portions 31 to the outer peripheral surface of the stator 50, which is the outer peripheral surface of the yoke portion 32. This ensures a wide magnetic flux path for the magnetic flux B in the yoke portion 32, and also allows the heat He to be efficiently transferred to the outer peripheral surface of the stator 50 and dissipated.

[0036] 5, in annular core sheet 30R, given yoke width W3 in radial direction X of yoke portion 32, length H3 in radial direction X of tooth portion 31, circumferential width W4 of tooth portion 31, distance C1 over which magnetic flux B flows in circumferential direction C shown in FIG. 6, plate thickness δ1 (not shown) of tooth portion 31, and plate thickness δ2 (not shown) of yoke portion 32, the condition under which the magnetic flux flow resistance of yoke portion 32 and tooth portion 31 are approximately equal is C1 / (2×H3)≈(W3×δ2) / (W4×δ1). Since an increase in W3 increases the volume and weight of rotating electric machine 100, increasing yoke width W3 under the condition W3<W4×C1 / (2×H3)×δ1 / δ2 can increase the output of rotating electric machine 100.

[0037] In the present disclosure, by increasing the number of steps in the width direction of the opening, the above-described bending process can be performed on a yoke portion that is large in width, thereby making it possible to increase the width of the yoke portion. This increases the effective magnetic path area. On the other hand, it is also easier to bend a yoke portion with a small diameter or a small number of slots and a large peripheral curvature between the slots.

[0038] Furthermore, in a configuration in which the core sheet is rolled to form a curve, the other side H2 of the core sheet is thinned by rolling, so the ratio (δ1 / δ2) becomes greater than 1, and the yoke width W3 must be increased to avoid impeding the flow of magnetic flux in the yoke portion. However, in the present disclosure, since δ1 / δ2 is approximately 1, the yoke width W3 can be reduced, and therefore a more compact and lightweight rotating electric machine 100 can generate high output.

[0039] Stator cores 30 having different configurations from those described above will now be described. Fig. 8 is a cross-sectional view showing another example of the schematic configuration of core sheet 30S constituting stator core 30 of stator 50 according to embodiment 1. Fig. 9 is a cross-sectional view showing another example of the schematic configuration of stator 50 according to embodiment 1.

[0040] 8, the multiple openings 35 constituting the opening group 35G are arranged side by side on a second extension line T2 extending from a second center line at the center of each tooth 31 in the width direction H. In this way, the number of opening groups 35G provided for each tooth 31 is equal to the number of magnetic poles constituted by the tooth 31. Therefore, in the annular core sheet 30R, the slits 35S are arranged on the second extension line T2 extending radially outward from the second center line at the center of each tooth 31 in the circumferential direction C.

[0041] Even with this configuration, the protrusion 39 having the second width W2 corresponding to the first width W1A, W1B of the opening 35 is stretched when the core sheet 30S is bent, and the core sheet 30S is bent into a ring shape while suppressing changes in the plate thickness.

[0042] The flow of magnetic flux and the flow of heat in the stator 50 configured in this manner will be described with reference to FIGS. 10 and 11 . FIG. 10 is a conceptual diagram showing the flow of magnetic flux in the stator 50 according to the first embodiment. FIG. 11 is a conceptual diagram showing the flow of heat in the stator 50 according to the first embodiment. Even in this configuration in which the slits 35S are provided on the radially outer side of the tooth portions 31 in the X direction, the slits 35S are arranged side by side on the second extension line T2 extending radially outward from the second center line of the tooth portions 31. Therefore, the electromagnetic steel sheets are connected in the X direction to both sides of the circumferential direction C of the tooth portions 31. Therefore, the magnetic flux B easily spreads in this portion, ensuring a magnetic flux path for the magnetic flux B and allowing the heat He to be efficiently transferred to the outer peripheral surface of the stator 50 and dissipated.

[0043] In this configuration, it is preferable to configure the annular core sheet 30R so that the distance between the inner wall of the slot SL on the outer side in the radial direction X and the slit 35S is equal to or greater than the width of the tooth portion 31 in the circumferential direction C. This allows for a configuration that does not impede the flow of magnetic flux and heat through the tooth portion 31.

[0044] The above explanation has mainly focused on wound cores in which strip-shaped core sheets are spirally wound and stacked into a cylindrical shape, but the same effects can also be obtained with strip cores manufactured by curving and forming a rectangular-shaped laminated core sheet made by stacking multiple rectangular core sheets.

[0045] Since the core sheet is rectangular, the crescent-shaped opening 35 may be positioned across the ends of the core sheet. In this case, divided notches may be provided at both ends of the core sheet so that the opening 35 is formed by butting the ends of the core sheet. On the other hand, the core sheet may not have openings 35 at its ends, but may have an approximately trapezoidal shape with the outer peripheral surface 32 extended, i.e., a shape such that both ends do not curve and deform to form a final cylindrical shape. In this case, the number of openings 35 provided is the number obtained by subtracting one from the number of magnetic poles formed by the tooth portion 31.

[0046] Below, the process of attaching the windings 40 to the annular stator core 30, which is a wound core, and the process of attaching the windings 40 to the rectangular parallelepiped stator core 30 (laminated core sheet), which is a strip core, will be described.

[0047] First, the windings 40 are attached to the annular stator core 30, which is a wound core, by inserting bundles of round wire coils wound around each tooth 31 into the slots SL from the inside in the radial direction X of the stator core 30, or by inserting groups of I-shaped or U-shaped rectangular wire coils into the slots SL from the end sides in the axial direction Z of the stator core 30. By joining the adjacent coil ends by welding or the like, it is possible to attach coils that generate a magnetic field when current is passed through them to the stator core.

[0048] The process of mounting the winding 40 on the rectangular stator core 30 will be described below. Fig. 12 is a conceptual diagram showing the connection state of the winding 40 on a laminated core sheet 30La formed by laminating a plurality of rectangular core sheets 30S according to embodiment 1. As shown in Fig. 12, the winding 40 includes a plurality of U-phase windings U1 wound continuously around the teeth 31 corresponding to the U phase, a plurality of V-phase windings V1 wound continuously around the teeth 31 corresponding to the V phase, and a plurality of W-phase windings W1 wound continuously around the teeth 31 corresponding to the W phase. The U-phase windings U1, the V-phase windings V1, and the W-phase windings W1 of the U-phase, V-phase, and W-phase are connected in parallel for each phase. The U-phase winding U1, V-phase winding V1, and W-phase winding W1 are each bent in accordance with the shape and position of the teeth 31 of the corresponding phase.

[0049] In mounting the windings 40, first, a mounting step is performed in which the U-phase winding U1, V-phase winding V1, and W-phase winding W1 are mounted on the corresponding phase teeth 31 of a rectangular parallelepiped laminated core sheet 30La formed by laminating multiple rectangular core sheets 30S. Then, the laminated core sheet 30La is curved into an annular shape to form the stator core 30 having an annular core sheet 30R, and the ends of the annular core sheet 30R are welded together to manufacture the cylindrical stator 50.

[0050] A first end U1-M of the U-phase winding U1, a first end V1-M of the V-phase winding V1, and a first end W1-M of the W-phase winding W1 are connected to the neutral point, and a second end U1-S of the U-phase winding U1, a second end V1-S of the V-phase winding V1, and a second end W1-S of the W-phase winding W1 are connected to the inverter side.

[0051] In this way, by performing the mounting process on the rectangular parallelepiped laminated core sheet 30La before bending it into an annular shape, the windings 40 of each phase can be mounted with a large opening width on the inner side of the slots SL in the radial direction X, thereby improving productivity. Furthermore, as described above, since there is no need to roll the other side H2 of the core sheet 30S, a stator with a large yoke width W3 can be manufactured, thereby providing a rotating electric machine 100 with high output. While the above example shows a configuration in which multiple U-phase windings U1, V-phase windings V1, and W-phase windings W1 are provided and connected in parallel for each phase, a configuration with only one U-phase winding U1, V-phase winding V1, and W-phase winding W1 may also be used.

[0052] Next, a configuration including a cooling structure for cooling the winding 40 will be described. Fig. 13 is a diagram showing an example of a configuration for mounting the winding 40 and the cooling pipe 80 to the laminated core sheet 30La according to embodiment 1. Fig. 14 is a diagram showing another example of a configuration for mounting the winding 40 and the cooling pipe 80 to the laminated core sheet 30La according to embodiment 1. Fig. 15 is a diagram showing the cooling pipe 80 mounted to the laminated core sheet 30La according to embodiment 1. For simplification of the drawing, the winding 40 is omitted from the illustration. Fig. 16 is an enlarged view showing the inside of portion AA of the cooling pipe 80 shown in Fig. 15.

[0053] As shown in Figure 13, in the installation process, a cooling pipe 80, through which a cooling medium such as oil flows, is brought into contact with the winding 40 on the other side H2 in the width direction H of the winding 40. Then, as shown in Figure 15, the cooling pipe 80 is sequentially bridged between adjacent slots SL, and disposed in each slot SL in a serpentine shape in the width direction H between both end faces of the laminated core sheet 30La in the axial direction Z. In this manner, the cooling pipe 80 and the winding 40 are curved together and disposed in each slot SL. Note that the cooling pipe 80 may be curved in advance in accordance with the shape of the slot SL before being disposed in the slot SL, or may be curved sequentially as it is disposed between the slots SL.

[0054] In this configuration, the rectangular parallelepiped laminated core sheet 30La also has a large opening width on the radially inner side of the slots SL, so the windings 40 and the cooling pipes 80 can be attached together from one side H1 in the width direction H of the laminated core sheet 30La. This greatly simplifies assembly, and also allows the use of a single seamless cooling pipe 80, which has no joints, eliminating the need to worry about unnecessary liquid leakage and achieving highly reliable cooling.

[0055] While FIG. 13 shows an example in which cooling pipe 80 is in contact with winding 40 along the other side H2 of winding 40, as shown in FIG. 14 , cooling pipe 80 may be sandwiched between winding 40 from both sides in the width direction H and in contact with winding 40, and cooling pipe 80 may be disposed relative to winding 40 so as to be able to cool winding 40.

[0056] 16, a plurality of oil holes 80H may be provided to deliver oil, which serves as a cooling medium, from inside the cooling pipe 80 to outside the pipe. In this way, the cooling medium delivered from the oil holes 80H comes into direct contact with the windings 40, enabling highly efficient direct cooling. In particular, if an oil hole is provided in a bent portion of the cooling pipe 80 located on the end side of the stator core 30 in the axial direction Z, the coil end portions can be cooled efficiently.

[0057] Fig. 17 is a cross-sectional view showing another example of the configuration of the opening 35 in the core sheet 30S according to embodiment 1. In the core sheet 30S shown in Fig. 17, a first convex portion 91T1 that protrudes toward one side H1 is formed on the inner wall of the other side H2 of the opening 35, and a first concave portion 91T2 that is recessed toward the other side H2 is formed on the inner wall of the one side H1. The positions and shapes of the first convex portion 91T1 and the first concave portion 91T2 on the core sheet 30S are adjusted so that they engage with each other in the annular core sheet 30R.

[0058] This suppresses the springback phenomenon, which occurs when the load applied during bending is released and the angle of the bent core sheet 30S returns to its original position due to the repulsion of compressive and tensile stresses. This increases the roundness of the outer peripheral surface of the formed stator core 30, improves the ease of attachment to the housing 70, and improves the fitting force to the housing 70, thereby suppressing the generation of vibrations and abnormal noise.

[0059] 18 is a cross-sectional view showing another example of the configuration of the stator 50 according to the first embodiment. As shown in FIG. 18, a configuration may be adopted in which magnetic material 92 is disposed in the slits 35S of the stator 50. This allows the gaps in the slits 35S to be filled with the magnetic material, thereby facilitating the passage of magnetic flux. Furthermore, if the outer peripheral surface of the magnetic material 92 is bonded to the inner wall of the slit 35S with an adhesive or the like, the gaps in the slits 35S can be more reliably filled with the magnetic material, thereby further improving the magnetic flux characteristics and suppressing springback.

[0060] The magnetic material 92 may be a sheet- or rod-shaped soft solid material having magnetic properties or containing magnetic powder, or a flowable hardened material containing magnetic powder. Preferably, the magnetic material 92 has adhesive properties.

[0061] 19 is a cross-sectional view showing another example of the configuration of the opening 35 in the core sheet 30S according to the first embodiment. A second-A recess 93T1 recessed toward the other side H2 is formed on the inner wall of the opening 35 on the other side H2 in the width direction H, and a second-B recess 93T2 recessed toward the one side H1 is formed on the inner wall on the one side H1. The positions and shapes of the second-A recess 93T1 and the second-B recess 93T2 are adjusted in the core sheet 30S so that they communicate with each other in the annular core sheet 30R. With this configuration, inserting an insert having approximately the same shape as the hole connecting the second-A recess 93T1 and the second-B recess 93T2 in the annular core sheet 30R can suppress springback.

[0062] The shape of the hole formed by the second A recess 93T1 and the second B recess 93T2 is not limited as long as it can be a diagonal I-shape, an E-shape, a Bodhidharma-shape, or any other shape that can be fixed by solid insertion.

[0063] FIG. 20 is a cross-sectional view showing another example of the configuration of the opening 35 in the core sheet 30S according to the first embodiment. First cutouts 90 are provided at both ends of the opening 35 in the longitudinal direction N to relieve stress. This configuration facilitates the proximity of the two walls of the opening 35 in the width direction H, making it easier to form the slit 35S in the annular core sheet 30R. The shape of the first cutouts 90 is not limited to a round opening; any shape is acceptable as long as it allows the opening at both ends of the opening 35 in the longitudinal direction N to be enlarged by a set dimension. If both ends of the opening 35 are acute-angled, the width of the machining tool becomes significantly smaller, making it difficult to machine a through opening. However, if cutouts greater than the set width are provided at both ends, the width of the machining tool becomes finite, making machining easier.

[0064] 21 is a cross-sectional view showing another example of the configuration of the openings 35 in the core sheet 30S according to embodiment 1. In the core sheet 30S, the openings 35 in the yoke portion 32 are arranged in a staggered pattern. This allows the core sheet 30S to bend more uniformly, and allows heat and magnetic flux to flow more uniformly.

[0065] FIG. 22 is a conceptual diagram showing another example configuration of the stator core 30 according to embodiment 1. The core sheet 30S having the configuration shown in FIG. 4 and the core sheet 30S having the configuration shown in FIG. 8 are stacked in the axial direction. In the stator core 30 thus formed, if the annular core sheet 30R having the configuration shown in FIG. 5 is the first annular core sheet 30R1 and the annular core sheet 30R having the configuration shown in FIG. 9 is the second annular core sheet 30R2, the first annular core sheet 30R1 and the second annular core sheet R2 are alternately stacked in the axial direction Z. By configuring the positions of the slits 35S in the circumferential direction C to differ in the axial direction Z, the heat flux in the tooth portion 31 is alleviated, improving heat dissipation.

[0066] The stator core 30 using the first annular core sheet 30R1 and the second annular core sheet R2 is not limited to a configuration in which the first annular core sheet 30R1 and the second annular core sheet R2 are alternately and simultaneously stacked in a spiral shape. For example, the stator core 30 may have a configuration in which multiple first annular core sheets 30R1 and multiple second annular core sheets 30R2 are stacked.

[0067] Although the above example shows the stator core 30 being formed by spirally winding the strip-shaped core sheet 30S, the present invention is not limited to this. For example, the strip-shaped core sheet 30S may be cut to a length corresponding to a set magnetic pole, and a plurality of independent annular core sheets 30R may be formed by stacking the cut core sheets.

[0068] The stator core configured as described above is a stator core formed by laminating annular core sheets each formed by bending a core sheet made of electromagnetic steel plate into a ring shape so that one side in the width direction is on the inner circumferential side, wherein the core sheet comprises, on one side in the width direction, a plurality of teeth portions arranged at predetermined intervals in the longitudinal direction to form magnetic poles, and a yoke portion on the other side in the width direction to connect the teeth portions, wherein the yoke portion in the core sheet comprises a plurality of crescent-shaped openings arranged at predetermined intervals in the longitudinal direction, with the apex side of the arc forming the opening positioned on the other side, and a protrusion protruding to the other side by a second width which is a length corresponding to the first width of the opening in the width direction, on the end face of the yoke portion located on the other side of each of the openings in the core sheet.

[0069] As described above, the core sheet constituting the stator core has a yoke portion with a plurality of crescent-shaped openings arranged at predetermined intervals in the longitudinal direction, with the apex of the arc constituting the opening positioned on the other side. The end face of the yoke portion located on the other side of each opening in the core sheet has a protrusion that protrudes to the other side by a second width corresponding to a first width in the width direction of the opening. Thus, the crescent-shaped openings formed in the core sheet are arranged so that the apex of the arc constituting the opening is positioned on the side where the core sheet is stretched. Furthermore, a protrusion that protrudes by a second width corresponding to the first width in the width direction of the opening is provided on the end face on the side where the core sheet is stretched. This suppresses changes in the sheet thickness when the core sheet is bent. By ensuring an appropriate sheet thickness in this way, when a rotating electric machine is required to be compact and high-output, an effective magnetic path area can be secured in the yoke portion, improving magnetic performance and enabling high torque output of the rotating electric machine. Furthermore, since the second width of the protrusion is a length corresponding to the first width of the opening, the protrusion can be pushed radially inward by the amount of the first width of the opening, thereby suppressing the amount of springback.

[0070] Here, in particular, laminated stator cores obtained by laminating electromagnetic steel sheets undergo final processes such as periphery welding to secure the layers together and ironing to adjust the outer peripheral shape. If the outer peripheral edges of the electromagnetic steel sheets become thin and axial gaps exist between the laminations, the thinned outer peripheral edges, which have become vulnerable to external forces, can cause problems such as deformation or damage during transport to the final process. In addition, poor welding can occur in the final process, and the weakened outer peripheral edges can become distorted or break (crack) during ironing, resulting in problems in terms of strength and quality.

[0071] Furthermore, when the stator core is used as part of the housing of a rotating electrical machine, such as in an automotive AC generator, the presence of gaps between the electromagnetic steel sheets on the outer periphery of the laminated core poses a major problem. Specifically, when attempting to clamp and secure both ends of the laminated core with a housing (frame) in the lamination direction (axial direction), a bending moment acts on the housing in a direction that reduces the gaps between the laminations, placing excessive stress on the assembly bolts, housing, etc. Furthermore, the reduced contact area between the housing and the stator reduces the securing force of the stator core, resulting in vibration and abnormal noise.

[0072] In the stator core of this embodiment configured as described above, core sheets having a constant thickness in the axial direction are densely stacked without gaps around the outer periphery of the stator core. This makes deformation of the outer periphery of the stator core less likely to occur, increasing the fixing force to the housing and reducing the occurrence of vibrations and abnormal noise during operation of the rotating electric machine. Furthermore, because the stator core is not formed by rolling core sheets, the winding diameter does not vary in the stacking direction. This allows for accurate assembly into the housing of the rotating electric machine.

[0073] Furthermore, since the tensile stress is applied to the protruding portion rather than the entire yoke portion, and deformation occurs at the protruding portion, residual stress in the yoke portion can be reduced, thereby increasing motor efficiency. According to the stator core, rotating electric machine, and stator manufacturing method of this embodiment, deformation and damage to the outer periphery of the stator core in this final process can be suppressed, ensuring reliability.

[0074] Although exemplary embodiments are described in the present disclosure, the various features, aspects, and functions described in the embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are anticipated within the scope of the technology disclosed in this specification. For example, variations in, addition to, or omission of at least one component are included.

[0075] 30S Core sheet, 30R Annular core sheet, 30R1 First annular core sheet, 30R2 Second annular core sheet, 30 Stator core, 31 Teeth portion, 32 Yoke portion, 35 Opening, 35G Opening group, 35S Slit, 39 Protrusion, 80 Cooling pipe, 91T1 First convex portion, 91T2 First concave portion, 92 Magnetic material, 93T1 Second A concave portion, 93T2 Second B concave portion, 94 Indentation, 100 Rotating electric machine, Arc1 First arc, Arc2 Second arc.

Claims

1. A stator core formed by laminating annular core sheets each formed by bending a core sheet made of electromagnetic steel plate into a ring shape so that one side in the width direction is on the inner circumferential side, wherein the core sheet comprises, on one side in the width direction, a plurality of teeth portions arranged at predetermined intervals in the longitudinal direction to form magnetic poles, and a yoke portion on the other side in the width direction connecting the teeth portions, wherein the yoke portion in the core sheet comprises a plurality of crescent-shaped openings arranged at predetermined intervals in the longitudinal direction, with the apex of the arc forming the opening positioned on the other side, and a protrusion protruding to the other side by a second width corresponding to a first width of the opening in the width direction is formed on the end face of the yoke portion located on the other side of each of the openings in the core sheet.

2. A stator core as described in claim 1, wherein the first width of the opening in the core sheet is adjusted so that the inner wall on one side of the opening and the inner wall on the other side face each other within a first distance set in the radial direction of the annular core sheet, forming a slit extending in the circumferential direction.

3. A stator core as described in claim 2, wherein the core sheet has a first convex portion that protrudes toward the one side on the inner wall on the other side of the opening, and a first concave portion that is recessed toward the one side on the inner wall on the one side of the opening, and the positions and shapes of the first convex portion and the first concave portion on the core sheet are adjusted so that the first convex portion and the first concave portion engage with each other on the annular core sheet.

4. A stator core as described in claim 2 or claim 3, wherein the yoke portion of the core sheet is provided with a group of openings in which a plurality of the openings are arranged in the width direction, and the second width of the protrusion in the core sheet at each position in the longitudinal direction is configured to be the total length of the first width of each of the plurality of openings constituting the group of openings located on one side of the protrusion at each position in the longitudinal direction.

5. A stator core as described in claim 4, comprising at least one of: a first annular core sheet in which the plurality of openings constituting the opening group in the core sheet are arranged as slits on first extension lines extending radially outward from a first center line of the circumferential center of a slot formed between the tooth portions in the annular core sheet; or a second annular core sheet in which the plurality of openings constituting the opening group in the core sheet are arranged as slits on second extension lines extending radially outward from a second center line of the circumferential center of the tooth portions, wherein the first width of the plurality of openings constituting each of the opening groups in the core sheet is configured to be larger for the openings located on the other side than for the openings located on the one side.

6. A stator core as claimed in any one of claims 2 to 5, wherein the outer peripheral surface between the protrusions of the yoke portion of the core sheet is formed into a curved surface which is the same as a circle having a radius equal to the axial center of the annular core sheet and an intersection point where the periphery of the protrusion on the core sheet intersects with the outer peripheral surface.

7. A stator core as claimed in any one of claims 2 to 6, wherein the annular core sheet is configured such that the distance between the radially outer inner wall of the slot formed between the teeth and the slit is equal to or greater than the circumferential width of the teeth.

8. A stator core according to any one of claims 1 to 7, wherein a plurality of the openings in the yoke portion of the core sheet are arranged in a staggered arrangement.

9. A stator core as set forth in any one of claims 1 to 8, wherein the yoke portion of the core sheet is provided with opening groups in which a plurality of the openings are arranged in the width direction, and the radial positions of each of the openings constituting each opening group are configured to be the same as the positions of each of the openings constituting adjacent opening groups.

10. A stator core as described in any one of claims 1 to 9, wherein a second A recess recessed toward the other side is formed in the inner wall of the core sheet on the other side of the opening, and a second B recess recessed toward the one side is formed in the inner wall of the core sheet on one side of the opening, and the positions and shapes of the second A recess and the second B recess in the core sheet are adjusted so that the second A recess and the second B recess are connected in the annular core sheet.

11. A stator core according to any one of claims 1 to 10, wherein first cutout portions are provided at both ends of the opening in the core sheet in the longitudinal direction.

12. A stator core according to any one of claims 2 to 7, wherein a magnetic body is disposed within the slit in the annular core sheet, and the outer circumferential surface of the magnetic body abuts against the inner wall of the slit.

13. A rotating electric machine comprising a stator using a stator core according to any one of claims 1 to 12, and a rotor arranged coaxially with the stator.

14. A method for manufacturing a stator using a stator core as defined in any one of claims 1 to 12, comprising: a U-phase winding as a phase winding wound continuously around each of the teeth corresponding to the U-phase; a V-phase winding as a phase winding wound continuously around each of the teeth corresponding to the V-phase; and a W-phase winding as a phase winding wound continuously around each of the teeth corresponding to the W-phase, wherein a laminated core sheet is formed by laminating a plurality of the core sheets, and after an attachment process is performed in which the U-phase winding, the V-phase winding, and the W-phase winding are attached to the teeth of the corresponding phases, the laminated core sheet is bent into an annular shape to form a stator formed by laminating the annular core sheets.

15. A method for manufacturing a stator as set forth in claim 14, wherein in the mounting step, a cooling pipe is brought into contact with the phase winding along the phase winding, and the cooling pipe is successively bridged over a plurality of adjacent slots formed between the teeth portions, and disposed in each of the slots while serpentine-shaped between the axial end faces of the laminated core sheet.

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