STATOR CORE OF A ROTATING ELECTRICAL MACHINE

Abstract

A stator core for a rotating electric machine includes a stator core having a circular back yoke and teeth protruding from the back yoke in a radial direction of the stator core. The stator core is formed by stacking core sheets in multiple layers. Each core sheet has convex portions provided at predetermined intervals in a circumferential direction and flat portions provided between adjacent convex portions in the circumferential direction. Each convex portion has a folded shape that is convex in a stacking direction and extends in the radial direction. The convex portions are stacked and overlap each other in the stacking direction. A plate thickness of the convex portion is smaller than a plate thickness of the flat portion.

Description

Technical area

[0001] This invention relates to a stator core of a rotating electrical machine. BACKGROUND

[0002] Conventionally, a stator core of a rotating electrical machine has a multi-layer stacked configuration of core sheets made of steel sheet material. Furthermore, a technique is known in which folded portions having a triangular mountain shape are formed at predetermined intervals in a circumferential direction on a strip-shaped core sheet during the manufacture of a stator core, and the core sheet is curved by these folded portions (see, for example, JP 2012-217279 A). Summary

[0003] However, in a configuration in which a core sheet has folded portions with a triangular mountain shape and the folded portions are stacked, a thickness in the stator core locally becomes thicker in a stacking direction because the steel sheet material in the folded portions is inclined to the stacking direction (i.e., an axial direction of the stator). As a result, gaps inadvertently form in the stator core at locations other than the folded portions. In this case, there is a concern that the stator core may not be strong enough in a configuration in which the core sheet is fixed by caulking, welding, or other means, or that this may result in reduced performance of a rotating electrical machine.

[0004] The present invention has been made in view of the above, and an object of the present invention is to provide a stator core of a rotating electrical machine capable of reducing formation of unintentional gaps between core sheets in a stacked state.

[0005] The means of solving the problem described above and the actions and effects thereof will be described below.

[0006] A stator core for a rotating electric machine includes a stator core having a circular back yoke and teeth protruding from the back yoke in a radial direction of the stator core. The stator core is formed by stacking core sheets in multiple layers. Each core sheet has convex portions provided at predetermined intervals in a circumferential direction and flat portions provided between adjacent convex portions in the circumferential direction. Each convex portion has a folded shape that is convex in a stacking direction and extends in the radial direction. The convex portions are stacked and overlap each other in the stacking direction. A plate thickness of the convex portion is smaller than a plate thickness of the flat portion.

[0007] In the stator core including multilayer stacked core sheets, the core sheets have the convex portions in a curved shape that is convex in the stacking direction and extends in the radial direction at predetermined intervals in the circumferential direction, and the core sheets are stacked with the convex portions overlapping each other in the stacking direction. In this case, the convex portion causes the core sheet to bulge into an arc, thereby appropriately forming the circular back yoke. In the core sheet, the plate thickness of the convex portion and the flat portion, which is a region between adjacent convex portions in the circumferential direction, is different, and the plate thickness of the convex portion is smaller than that of the flat portion.As a result, the difference in the thickness of the steel plate material between the convex and flat portions in the stacking direction becomes small when the steel plate material in the convex portion is inclined to the stacking direction (i.e., the axial direction of the stator). As a result, unintentional gaps between core sheets in the stacked stator core are prevented, thereby reducing problems such as insufficient stator core strength. Short description of the drawings Fig. 1 shows a perspective view of a stator. Fig. 2 shows a front view of the stator. Fig. 3 shows a top view of the stator core. Fig. 4A is an enlarged view illustrating a plan view of a portion of a core sheet. Fig. Figure 4B is an enlarged diagram illustrating a cross-sectional view of a portion of a core sheet. Fig. Figure 5 shows a diagram illustrating the manufacturing process of the stator core. Fig. Figure 6A shows a cross-sectional view of the core sheet. Fig. 6B shows a cross-sectional view of the core sheet in a stacked state of the core sheet. Fig. 6C shows a cross-sectional view of the core sheet from an outer side of a yoke formation portion 31 in a radial direction. Fig. Figure 7A shows a diagram illustrating a pain view of the core sheet. Fig. Figure 7B is a diagram illustrating a side view of the core sheet. Fig. Figure 8 shows a diagram illustrating the core sheet. Fig. 9 is a diagram illustrating a core sheet of a first modification. Fig. 10 is a diagram illustrating a core sheet of the first modification. Fig. 11 is a cross-sectional view illustrating a state in which a stator winding is assembled with the stator core of the first modification. Fig. 12 is a cross-sectional view illustrating a state in which a stator winding is assembled with a stator core of a second modification. Fig. 13 is a diagram illustrating a core sheet of the second modification. Fig. 14A is a diagram illustrating an inner shape of a core sheet of a third modification. Fig. 14B is a diagram illustrating an external shape of a core sheet of a third modification. Fig. 15A is a diagram illustrating a first sheet of a second embodiment. Fig. 15B is a diagram illustrating a second sheet of a second embodiment. Fig. 16A is a diagram illustrating the core sheet of the second embodiment. Fig. 16B is a diagram illustrating the core sheet of the second embodiment in first and second sheet stacking states. Fig. 16C is a diagram illustrating the core sheet of the second embodiment in a multi-layer stacked state. Fig. Figure 17 shows a diagram illustrating another example of a core sheet. DETAILED DESCRIPTIONFirst embodiment

[0008] Hereinafter, an embodiment of a stator of a rotating electric machine mounted on a hybrid vehicle or an electric vehicle will be described below with reference to the drawings. In the following embodiments and modifications, the same or equivalent parts will be denoted by the same reference numerals in the drawings, and detailed explanations thereof will be omitted. A rotating electric machine is, for example, an electric motor, a generator, or a motor generator (MG).

[0009] The rotating electric machine of the present embodiment is applicable to both permanent magnet synchronous motors and wound field magnet and induction machines and has three-phase windings. The rotating electric machine includes a cylindrical stator 10, which is Fig. 1, and a rotor (not shown) arranged on an inner side of the stator 10 in a radial direction. The rotor is rotatable relative to the stator 10 about a rotation axis. Hereinafter, an axial direction refers to an axial direction of the stator 10, that is, the axial direction of the rotation axis of the rotor; a radial direction refers to the radial direction of the stator 10, that is, a direction passing through a center of the rotation axis of the rotor and orthogonal to the rotation axis; and a circumferential direction refers to a circumferential direction of the stator 10, that is, the circumferential direction around the rotation axis of the rotor.

[0010] As in the Fig. 1 and Fig. As shown in Fig. 2, the stator 10 includes a stator core 11 having an annular shape and a multi-phase stator winding 12 wound around the stator core 11. The rotating electric machine of the present embodiment is of an inner rotor type, and the rotor is arranged to be rotatable on the inside of the stator 10 in the radial direction. The stator winding 12 has a 3-phase winding with a U-phase winding, a V-phase winding, and a W-phase winding as phase windings for each phase, and a power line bus bar 13 is connected to one of the ends, and a neutral line bus bar 14 is connected to the other of the ends of the phase windings of each phase.In the stator winding 12, a portion overlapping the stator core 11 in the axial direction is a coil side CS, and a portion on both sides in the axial direction located outside the stator core 11 in the axial direction is a coil end CE.

[0011] Fig. 3 is a plan view of the stator core 11. The stator core 11 is composed of core sheets 30 made of steel sheet material (electromagnetic steel sheet) stacked in multiple layers in the axial direction and fixed by caulking, welding, bonding, or other means. In the present embodiment, the stator core 11 is a spiral stator core structure composed of strip-shaped core sheets 30 stacked in a spiral shape. Since the stator core 11 is the spiral stator core structure, material yield, material savings, and cost reduction can be improved.

[0012] The stator core 11 includes a back yoke 21 in an annular shape and teeth 22 projecting radially inward from the back yoke 21 and arranged at a predetermined pitch in the circumferential direction, with slots 23 formed between adjacent teeth 22. The slots 23 have an opening shape extending in the radial direction as the longitudinal direction and are provided at equal intervals in the circumferential direction in the stator core 11. The slots 23 are open radially inward of the stator core 11.

[0013] As in Fig. 1, each of the 23 slots is wound with the stator winding 12 at a predetermined slot pitch. The stator winding 12 is formed in a state where, for example, an insulated conductive wire is used in which a conductor is covered with an insulating layer, and the conductive wires are accommodated in multiple layers in the radial direction in the slots 23. In the present embodiment, the stator winding 12 has a segmented structure including conductor segments 15 having an abbreviated U-shape and joined together to form the stator winding 12. In the stator winding 12, the coil end CE on one side of the axial direction is formed by turn portions of each conductor segment 15, and the coil end CE on the other side of the axial direction is formed by connecting the ends (straight portions) of the various conductor segments 15 to each other.The stator winding 12 generates a magnetic flux when electrical power is supplied to each phase via an inverter (not shown).

[0014] In the present embodiment, a core sheet 30 of the core sheets has convex portions 34 having a folded shape that is convex in the stacking direction. The convex portions have a shape that extends in the radial direction. The convex portions 34 are provided at predetermined intervals in the circumferential direction. This causes the core sheet 30 to be bent into an arcuate shape. The details will be described below.

[0015] Fig. 4A is an enlarged view of a portion of the core sheet 30. Fig. 4A a plan view of the core sheet 30 and Fig. 4B is a cross-sectional view in a 4B-4B line segment of Fig. 4A. As in Fig. 4A, the core sheet 30 roughly includes a long strip-shaped bracket forming portion 31, which is a portion forming the back yoke 21, and a tooth forming portion 32, which is a portion forming the teeth 22. The back yoke 21 is formed by stacking the core sheet 30 so that the yoke forming portion 31 overlaps in the axial direction. The teeth 22 are formed by overlapping the tooth forming portion 32 in the axial direction. In other words, in the stator core 11, a portion of the core sheet 30 corresponding to the yoke forming portion 31 is the back yoke 21, and a portion corresponding to the tooth forming portion 32 is the teeth 22. In the core sheet 30, a space between the circumferentially aligned tooth forming portions 32 is a slit recess 33 for slit formation.

[0016] The yoke-forming portion 31 has a convex portion 34 that is convexly curved in the stacking direction and extends in the radial direction. The convex portion 34 has a larger protruding height on an inner side of the radial direction and a smaller protruding height on an outer side of the radial direction in the yoke-forming portion 31, and is triangular in plan view with a smaller width on the outer side of the radial direction. The convex portion 34 is provided at a position radially outside each slit recess 33. As a result, the convex portion 34 is provided at predetermined intervals in the circumferential direction (see Fig. 4B). In the yoke forming portion 31, a portion between adjacent convex portions 34 in the circumferential direction is a flat portion 35. The flat portion 35 of the yoke forming portion 31 and the tooth forming portion 32 are both flat and continuous in the radial direction.

[0017] Since the yoke forming portion 31 has the convex portions 34 at predetermined intervals, a circumferential length of an inner portion in the radial direction of the yoke forming portion 31 in plan view is shorter than a circumferential length of an outer portion in the radial direction, and the core sheet 30 is curved into an abbreviated arc shape. When the core sheet 30 is stacked in the stator core 11 in multiple layers, the convex portions 34 and flat portions 35 overlap in the stacking direction. In this case, a concave side of the convex portion 34 is an inner convex portion 36, and the core sheet 30 is laminated so that the convex portion 34 of a lower layer is inserted into the inner convex portion 36 of the convex portion 34 of an upper layer.

[0018] Fig. 5 is a diagram illustrating the manufacturing process of the stator core 11. In Fig. 5, a region indicated by “X1” shows the core sheet 30 before it is spirally curved, and a region beyond “X1” shows the core sheet 30 after it is spirally curved.

[0019] Before forming into a curve, the core sheet 30 is formed into a flat predetermined shape by pressing, for example, steel sheet material. The yoke forming portion 31 has a straight strip shape, and from the yoke forming portion 31, the tooth forming portions 32 are formed at predetermined intervals to extend orthogonally to the longitudinal direction of the yoke forming portion 31. In the pre-curving stage, opposite portions of the slot recess 33 facing each other in the longitudinal direction of the yoke have an abbreviated V shape that widens toward the tip of the teeth.

[0020] Then, using a bending jig (not shown), the cylindrical stator core 11 is formed while the core sheet 30 is spirally bent by bending the yoke forming portion 31. In other words, the core sheet 30 is curved into an abbreviated arc shape by bending and forming the convex portions 34 at predetermined intervals on the yoke forming portion 31. The convex portion 34 is formed such that an inner portion is wider in the radial direction and an outer portion is narrower in the radial direction in plan view, so that a circumferential length of the inner portion in the radial direction is different from a circumferential length of the outer portion in the radial direction, and the core sheet 30 is curved into an abbreviated arc shape.After forming the curvature, opposite portions facing each other in the longitudinal direction of the yoke in the slot recess 33 are parallel to each other.

[0021] The spiral-shaped core sheets 30 are stacked in multiple layers, with the convex portions 34 overlapping each other in the stacking direction. As a result, the cylindrical stator core 11 is formed. Subsequently, the flat portion 35 is axially fixed in the stator core 11 by caulking, welding, bonding, or other means.

[0022] Incidentally, in a configuration where the core sheet 30 has the convex portions 34, when a plate thickness of the steel sheet material in the convex portion 34 and the flat portion 35 is the same, a plate thickness in the stacking direction (ie, stator axial direction) is thicker in the convex portion 34 than in the flat portion 35. Therefore, there is a problem that gaps may be generated between the flat portions 35 in the stacked state of the core sheet 30, resulting in insufficient strength of the stator core 11 and reduced performance of the rotating electrical machine.

[0023] Therefore, in the present embodiment, a plate thickness of the convex portion 34 is different from a plate thickness of the flat portion 35 in the core sheet 30, and the configuration is in Fig. 6A. In Fig. 6A, the plate thickness of the flat portion 35 is "T1" and that of the convex portion 34 is "T2," and the relationship between these T1 and T2 is T1>T2. The plate thicknesses T1, T2 correspond to a wall thickness in a direction perpendicular to a plate surface in the steel sheet material comprising the core sheet 30.

[0024] In this case, the plate thickness T2 of the convex portion 34 is smaller than the plate thickness T1 of the flat portion 35. As a result, in the Fig. 6B, the formation of a gap between the flat portions 35 is reduced, and each flat portion 35 is in contact with each other. It is desirable to make a thickness T3 of the convex portion 34 in the stacking direction equal to the plate thickness T1 of the flat portion 35 (ie, T1 = T3). In such a case, the flat portions 35 can be in contact with each other in the stacking direction, and the convex portions 34 can be in contact with each other.

[0025] A relationship between the plate thickness T1 of the flat portion 35 and the thickness T3 of the convex portion 34 in the stacking direction may be T1 > T3, in addition to T1 = T3. Even with this configuration, the formation of gaps between the flat portions 35 in the stacked state of the core sheet 30 is reduced.

[0026] In the present embodiment, the convex portion 34 is provided in the yoke forming portion 31 from an inner end portion to an outer end portion in the radial direction, that is, in the entire radial direction of the yoke forming portion 31, and is formed to protrude from the flat portion 35 in the entire radial direction of the yoke forming portion 31. In other words, the convex portion 34 is formed so that the convex portion 34 protrudes from the flat portion 35 even at the outer end portion of the yoke forming portion 31 in the radial direction, that is, a portion where a protruding height of the convex portion 34 is the smallest.

[0027] Here, in the core sheet 30, when the protrusion height of the convex portion 34 at the outer end portion of the yoke forming portion 31 is zero in the radial direction, the convex portion 34 protrudes axially from the zero protrusion height in the radial direction, a direction in which the convex portion 34 extends. In this case, at a leading portion of the convex portion 34, it becomes difficult to bend and shape the steel sheet material and thin it to form the convex portion 34. In this regard, as described above, the convex portion 34 is formed such that the convex portion 34 protrudes from the flat portion 35 even at the outer end portion of the yoke forming portion 31 in the radial direction, that is,the portion where the protruding height of the convex portion 34 is minimal, which facilitates bending and forming of the steel plate material and thinning thereof to form the convex portion 34.

[0028] Fig. 6C shows a side view of the core sheet 30 as seen from an outer side of the yoke forming portion 31 in the radial direction. As shown in Fig. 6C, at the outer end position of the convex portion 34 in the radial direction, a depth T4 of the inner convex portion 36 is greater than the plate thickness T1 of the flat portion 35. The depth T4 of the inner convex portion 36 may be the same as the plate thickness T1 of the flat portion 35.

[0029] During the manufacture of the stator core 11, when the convex portion 34 is formed on the core sheet 30 by the bending device and the core sheet 30 is bent, the convex portion 34 is bent and formed while the steel plate material is thinned by pressure rolling, at a position to be formed from the convex portion 34 of the yoke forming portion 31. For example, a pressure device that clamps the core sheet 30 in a thickness direction of the core sheet 30 should be used, and a thickness of a thin-walled portion should be adjusted while the steel plate material is thinned by pressure of the pressure device.The bending machine can perform bending and thinning of steel sheet material as simultaneous processes, or it can perform bending and thinning of steel sheet material as separate processes, such as bending steel sheet material and subsequent thinning, or bending steel sheet material after thinning. In short, the bending device should complete the bending and thinning of the steel sheet material before stacking the core sheets 30.

[0030] In the core sheet 30 of the present embodiment, it is recommended that a pre-bending area be defined in the steel sheet material before folding, taking into account that thinning is performed in addition to folding the steel sheet material. In other words, when thinning the steel sheet material, longitudinal strain occurs in the steel sheet material, so an area of ​​the pre-bending area should be set smaller to accommodate this strain.

[0031] Incidentally, when the core sheet 30 is bent by the convex portions 34 provided at predetermined intervals in the circumferential direction, the yoke forming portion 31 becomes polygonal, and the back yoke 21 is formed into a polygonal cylindrical shape by the polygonal yoke forming portion 31. In the rotating electric machine, the stator core 11 may be mounted in an assembled state on the inner circumference of a cylindrical casing. In this case, the stator core 11 and the casing are in multi-point contact on an outer surface of the stator core 11, and there is a concern that back pressure in the stator core 11 is concentrated at a contact area with the casing, resulting in a reduced fastening force due to deformation in a vicinity of the contact area.Additionally, there are concerns that high partial counter voltages applied to the stator core 11 may increase the core iron loss due to residual stresses, resulting in lower motor efficiency.

[0032] Therefore, in the present embodiment, in the core sheet 30, the outer end portion of the yoke formation portion 31 in the radial direction (i.e., an edge in the radial direction opposite to the tooth formation portion 32) is partially rolled, and a portion located between each convex portion 34 in the circumferential direction is formed circularly in plan view. More specifically, a rolled portion 41 extending in the circumferential direction is provided at the outer end portion of the yoke formation portion 31, as shown in FIGS. Fig. 7A, Fig. 7B. In this case, the stator core 11 has an annular shape, while the partial rolling of the outer end portion of the yoke configuration portion 31 prevents the outer surface of the stator core 11 from assuming a polygonal shape because the convex portion 34 is formed on the core sheet 30. In the present embodiment, partial rolling is performed in the core sheet 30, so that the increase in core iron loss due to rolling can be reduced.

[0033] As in Fig. 8, the rolled portion 41 should be located at the outer edge portion of the back yoke 21 except for the convex portion 34. In this case, since the rolled portion 41 is intermittently formed in the yoke forming portion 31 while avoiding the convex portion 34, the deformation of the outer edge portion caused by the flattening of the convex portion 34 can be reduced.

[0034] It is possible to obtain the following excellent effects according to the present embodiment described in detail.

[0035] In the core sheet 30, the plate thickness T2 of the convex portion 34 is different from the plate thickness T1 of the flat portion 35, and the plate thickness T2 of the convex portion 34 is smaller than the plate thickness T1 of the flat portion 35. As a result, even if the steel plate material at the convex portion 34 is inclined to the stacking direction (the stator axial direction), the difference in the thickness of the steel plate material between the convex portion 34 and the flat portion 35 in the stacking direction becomes small. As a result, the formation of unintentional gaps between the core sheets 30 in the stacked state in the stator core 11 can be reduced.

[0036] In this case, caulking, welding, and bonding between the core sheets 30 can be performed smoothly, and the reduction in the strength of the stator core 11 can be reduced. In addition, the reduction in torque output due to the lower occupancy ratio of the magnetic material in the stator core 11 and the increase in body size due to gaps can be reduced. Furthermore, the core sheet 30 adheres tightly in the stacking direction in the stator core 11, improving heat dissipation due to reduced thermal resistance, resulting in higher power output.

[0037] The convex portion 34 of the core sheet 30 is formed such that the convex portion 34 protrudes from the flat portion 35 in the yoke forming portion 31 with a larger protrusion height within the radial direction and a smaller protrusion height outside the radial direction. The convex portion 34 also protrudes from the flat portion 35 even at the outermost radial portion of the yoke forming portion 31, which is a portion where the protrusion height of the convex portion 34 is the smallest.In this case, compared with a configuration in which the protruding height of the convex portion 34 in the outermost radial direction of the yoke forming portion 31 in the core sheet 30 is zero, it is easier to form the convex portion 34 by bending and forming the steel sheet material and making it thinner, and the convex portion 34 can be properly formed by thinning the steel sheet material.

[0038] At the outermost radial position of the convex portion 34, the depth T4 of the inner convex portion 36 is equal to or greater than the plate thickness T1 of the flat portion 35. This enables the core sheets 30 to be better connected to each other over the entire radial range of the yoke forming portion 31.

[0039] The rolled portion 41 is provided at the outer edge of the yoke forming portion 31 of the core sheet 30, and portions between each convex portion 34 in the circumferential direction are formed into a circular arc in plan view by the rolled portion 41. In this case, the stator core 11 has an annular shape, while the partial rolling of the outer end portion of the yoke forming portion 31 prevents the outer surface of the stator core 11 from assuming a polygonal shape because the convex portion 34 is formed on the core sheet 30.

[0040] The rolled portion 41 may be provided at a portion except the convex portion 34 in the yoke forming portion 31 of the core sheet 30, whereby deformation of the outer edge of the yoke forming portion 31 caused by flattening of the convex portion 34 can be reduced.

[0041] Modifications of the first embodiment are shown below. First Amendment

[0042] In one in the Fig. 9, Fig. 10, a convex portion 34 is trapezoidal, an upper base 37 of the convex portion is parallel to the flat portion 35. In this case, the upper base 37, as in Fig. 9 is formed by flattening a top surface in a certain area in the radial direction, including the innermost edge (side of the slit recess 33) in the radial direction in the convex portion 34.

[0043] As in Fig. As shown in Figure 10, in the convex portion 34, a plate thickness T11 of the upper base 37 is greater than a plate thickness T12 of an inclined portion. The plate thickness T11 of the upper base 37 should be the same as the plate thickness T1 of the flat portion 35. However, the plate thickness T11 of the upper base 37 may be the same as the plate thickness T12 of the inclined portion, or it may be smaller than the plate thickness T1 of the flat portion 35.

[0044] Fig. 11 a cross-sectional view of the stator core 11 with assembled stator winding 12. As in Fig. 11, the stator winding 12 is housed in a slot 23 of the stator core 11. The stator winding 12 is composed of conductor segments 15 arranged in the radial direction. Each conductor segment 15 is positioned close to each other in the radial direction within the slot 23 (coil side CS) and is also spaced apart from each other in the radial direction outside the slot 23 (coil end CE). In this case, at the coil end CE, one conductor segment 15 (the stator winding 12) of the conductor segments is bent and formed radially outward, opposite to a rotor air gap, so that when the convex portion 34 protrudes axially into the stator core 11, interference between the convex portion 34 and the conductor segment 15 is a concern.Here, as described above, the convex portion 34 is formed in a trapezoidal shape, with an upper portion being the upper base 37, so that interference between the convex portion 34 and the conductor segment 15 can be reduced.

[0045] In addition, by forming the convex portion 34 trapezoidal, a coil end height of the stator winding 12 can be reduced, which enables downsizing of the rotating electric machine, and a magnetic path length of the convex portion 34 is shorter than that of a triangular convex portion 34, resulting in higher torque output by reducing the magnetic resistance. Second Amendment

[0046] As in Fig. As shown in FIG. 12, at least one core sheet 30 serving as the axial end of the stator core 11 may be configured with at least one portion including a tip cut out at the convex portion 34. In this case, the top surface of the convex portion 34 of the core sheet 30, which is the axial end of the stator core 11, should be cut off along a line perpendicular to the axial direction. In the stator core 11, the core sheet 30 should be laminated with the top surface of the convex portion 34 cut off at the axial end, and the core sheet 30 without the top surface of the convex portion 34 cut off except at the axial end should be cut off. Fig. Figure 13 shows the core sheet 30 used at the axial end of the stator core 11. This core sheet 30 differs from the core sheet 30 (compare Fig. 4), except at the axial end, in that the top of the convex portion 34 is cut out to form a notch 38.

[0047] According to the stator core 11 of the Fig. 12, Fig. 13, an axial length of the stator core 11 is shortened by partially cutting out the convex portion 34, thereby increasing an amount of core substance without increasing the axial length of the stator core 11. This increases the magnetic path width and improves torque output. Third modification

[0048] In a core sheet 30, an angle of a triangular vertex of a convex portion 34 may be configured to differ between the radially inner and radially outer sides of a yoke shape portion 31. Fig. 14A, Fig. 14B show that shapes in the convex portions 34 differ between the inside and the outside of the radial direction in the convex portion 34 of the core sheet 30. Fig. 14A shows an inner shape of the convex portion 34 in the radial direction and Fig. 14B shows an outer shape of the convex portion 34 in the radial direction.

[0049] As in the Fig. 14A, Fig. As shown in FIG. 14B, protruding heights of the convex portions 34 differ from each other, as do angles of the triangle vertices. In this case, the angle at the apex of the triangle within the radial direction is "θ1," and the angle at the apex of the triangle outside the radial direction is "θ2," and the relationship between θ1 and θ2 is θ1 < θ2. The plate thicknesses of the convex portions 34 are different between the inner and outer radial directions. In this case, a plate thickness of the convex portion 34 within the radial direction is "T21," and a plate thickness of the convex portion 34 outside the radial direction is "T22," and a relationship between T21 and T22 is T21 < T22. The plate thickness of the flat portion 35 is the same both inside and outside the radial direction (T23).

[0050] In the convex portion 34 of the core sheet 30, the angle of the top of the triangle is different between the inner and outer peripheral sides of the yoke forming portion 31 (rear yoke 21) in the radial direction, which allows the circumferential length of the yoke forming portion 31 to be different between the inner and outer peripheral sides of the yoke forming portion 31, which makes it possible to form a curvature of the yoke forming portion 31. In the convex portion 34, the angle of the triangular vertex on the outer side of the yoke forming portion 31 in the radial direction is larger than on the inner side in the radial direction, and the plate thickness is also larger.This results in a smaller inclination angle with respect to the flat portion 35 at the outer end portion in the radial direction, where the protruding height of the convex portion 34 is smaller, and the increase in thickness in the axial direction of the stator due to the inclination is smaller. Therefore, the degree of thinning of the steel sheet material on the outer side of the radial direction can be reduced, the bend size becomes smaller, and the steel sheet material can be thinned accordingly. Second embodiment

[0051] In the present embodiment, a configuration for distinguishing a plate thickness between a convex portion 34 and a flat portion 35 in a core sheet 30 is different from the first embodiment. Here, the core sheet 30 is composed of a first sheet 51 and a second sheet 52, each of which is made of steel sheet material and has different shapes. By overlapping the first sheet 51 and the second sheet 52, the plate thickness of the convex portion 34 is smaller than that of the flat portion 35.

[0052] Fig. 15A a plan view of the first sheet 51 and Fig. 15B is a plan view of the second sheet 52. As in Fig. 15A, the first sheet 51 includes a yoke forming portion 31 and tooth forming portions 32 with a slit recess 33 between each of the tooth forming portions 32. A tooth forming portion 32 of the tooth forming portions is provided with convex portions 34 lined up in the circumferential direction at predetermined intervals, and a space between each convex portion 34 is a flat portion 35A. The convex portion 34 is located radially outside the slit recess 33. In the yoke forming portion 31 of the first sheet 51, the convex portion 34 and the flat portion 35A are continuously provided alternately in the circumferential direction.

[0053] On the other hand, the second sheet 52, as shown in Fig. 15B, a yoke forming portion 31 and tooth forming portions 32, with a slit recess 33 provided between each tooth forming portion 32. The second sheet 52 differs from the first sheet 51 in that, in the yoke forming portion 31, the outer side of the slit recess 33 in the radial direction is a notch 53 (empty portion) without the convex portion 34, and a portion between the notches 53 in the circumferential direction is a flat portion 35B. In other words, the second sheet 52 is composed of portions of the first sheet 51 except for the convex portion 34.

[0054] In the present embodiment, the first sheet 51 and the second sheet 52 are stacked as the core sheet 30, and the core sheet 30 is composed of the yoke formation portion 31 and the tooth formation portions 32 of the first core sheet 51 and the second core sheet 52, respectively, adhered to each other. In this case, the first sheet 51 and the second sheet 52 are superimposed on each other, with the yoke formation portion 31 and the tooth formation portion 32 respectively aligned. This allows the convex portion 34 of the first sheet 51 and the notch 53 of the second sheet 52 to be placed in the same position in the core sheet 30.

[0055] Here, in the first sheet 51, between an innermost portion in the radial direction and an outermost portion in the radial direction (outer peripheral edge) of the yoke forming portion 31, the flat portion 35A is provided continuously in the circumferential direction in a Y-section at the outer peripheral edge, and the convex portion 34 is provided inward in the radial direction from the Y-section. In other words, the first sheet 51 has the convex portion 34 in the yoke forming portion 31 from the innermost position in the radial direction to a middle position in the radial direction.Similarly, in the second sheet 52, between the innermost portion in the radial direction and the outermost portion in the radial direction (outer peripheral edge) of the yoke-forming portion 31, the flat portion 35B is provided continuously in the circumferential direction in the Y-portion at the outer peripheral edge, and the notch 53 is provided inward in the radial direction from the Y-portion. As a result, in the second sheet 52, portions that become on both sides of the convex portion 34 in the circumferential direction when the second sheet 52 is overlapped on the first sheet 51 are continuous at the outer peripheral edge.

[0056] As in Fig. As shown in FIG. 16A, a plate thickness of the flat portion 35A is "T31" and a plate thickness of the convex portion 34 is "T32" in the first sheet 51, and a relationship between T31 and T32 is T31=T32. In other words, the convex portion 34 in the first sheet 51 is formed by bending without thinning the steel sheet material.

[0057] As in Fig. 16B, when the first sheet 51 and the second sheet 52 overlap each other, the flat portions 35A, 35B of each sheet 51, 52 are overlapped (i.e., adhered to each other) to form the flat portion 35, and in this state, a plate thickness T41 of the flat portion 35 is greater than the thickness T32 of the convex portion 34. In other words, the plate thickness T32 and T41 are in a relationship of T32 < T41. The plate thickness T41 of the flat portion 35 should be the same as the thickness T33 in the stacking direction in the convex portion 34. However, T41 > T33 is acceptable.

[0058] Fig. Figure 16C shows the core sheet 30, which consists of the first sheet 51 and the second sheet 52 laminated in multiple layers. In this state, the convex portions 34 and the flat portions 35 of the core sheet 30 overlap in the stacking direction, and no gap is formed between the flat portions 35. As shown in Fig. As shown in Fig. 16B, the stator core 11 is composed of the first lamination 51 in a first layer, which is the axial end face, and the core lamination 30 composed of the first lamination 51 and the second lamination 52 in the second and subsequent layers. However, it is also possible to have a configuration in which the core lamination 30 composed of the first lamination 51 and the second lamination 52 is laminated in all layers of the stator core 11 (with the second lamination 52 disposed on the axial end face).

[0059] When manufacturing the stator core 11, the first sheet 51 and the second sheet 52 are prepared, each formed by pressing, for example, steel sheet material into a flat predetermined shape. Each of these sheets 51, 52 is then curved into an arc shape and discharged at the same speed while stacking them on top of each other to form the core sheet 30, and the cylindrical stator core 11 is manufactured by stacking multiple layers of the core sheets 30. In this case, the first sheet 51 is curved into an abbreviated arc shape, while the convex portion 34 is bent and formed on the yoke forming portion 31 using a bending device. In the present embodiment, the convex portion 34 is bent and formed without thinning the steel sheet material by the press rolling process.On the other hand, the second lamination 52 is curved with the same curvature as the first lamination 51 without being folded and formed. The respective curved and formed first and second laminations 51 and 52 are then stacked on top of each other and laminated into a multilayer in this state. As a result, the stator core is manufactured in a cylindrical shape.

[0060] Here, the second sheet 52 is at a portion outside the radial direction in the yoke forming portion 31 (the Y-portion in Fig. 15), continuously in the circumferential direction. Therefore, the second sheet 52 is fed continuously together with the first sheet 51, and the first sheet 51 and the second sheet 52 are stacked one on top of the other in a suitable manner.

[0061] Both the first plate 51 and the second plate 52 have flat portions 35A, 35B connected circumferentially outside the radial direction of the yoke forming portion 31. Therefore, even in a configuration where bending is performed on the first plate 51 and not on the second plate 52, a circumferential pitch of the tooth-forming portions 32 and the slot recess 33 in both the first plate 51 and the second plate 52 can be reduced.

[0062] According to the present embodiment, the following effects can be obtained.

[0063] The core sheet 30 is composed of the first sheet 51, which has the convex portion 34 and is continuous in the circumferential direction, and the second sheet 52, which includes a portion of the first sheet 51 except the convex portion 34. In this case, the overlap of the first sheet 51 and the second sheet 52 allows the plate thickness of the flat portion 35 to be relatively increased without reducing the thickness of the convex portion 34. Therefore, it is easy to achieve a configuration in which the plate thickness of the convex portion 34 is smaller than that of the flat portion 35.

[0064] In the first sheet 51, the plate thickness of the convex portion 34 and the plate thickness of a portion other than the convex portion (the flat portion 35A) are the same, and in the core sheet 30, the plate thickness of the convex portion 34 is smaller than that of the flat portion 35 when the second sheet 52 is overlapped on the first sheet 51. In this case, even if the plate thicknesses for the convex portion 34 and the flat portion 35A are the same in the first sheet 51, in other words, even without thinning the steel sheet material, it is easy to achieve a configuration in which the plate thickness of the convex portion 34 is smaller than that of the flat portion 35 in the core sheet 30.

[0065] In the first sheet 51, a portion of the convex portion 34 extends in the radial direction from the innermost edge of the yoke forming portion 31 in the radial direction to a central position in the radial direction, thereby configuring the second sheet 52 in which portions that are the peripheral edges of the convex portion 34 in the yoke forming portion 31 are continuous at the outermost edge in the radial direction. This allows both the first sheet 51 and the second sheet 52 to be continuous in the longitudinal direction and enables overlapping work of these respective sheets 51, 52 with each other to be performed appropriately. Other embodiments

[0066] It is also possible to modify the embodiment described above, for example, as follows.

[0067] In the above second embodiment, the plate thickness T31 of the flat portion 35A and the plate thickness T32 of the convex portion 34 in the first sheet 51 are the same (see Fig. 16A), however, this can be changed. For example, the plate thickness T32 of the convex portion 34 may be smaller than the plate thickness T31 of the flat portion 35A in the first sheet 51. In this case, the first sheet 51 should be made of steel sheet material that is bent and thinned to form the convex portion 34. In the first sheet 51, the convex portion 34 may be configured to be thinner due to elongation caused by bending of the steel sheet material. In any case, the core sheet 30 should have a plate thickness T32 of the convex portion 34 that is smaller than the plate thickness T41 of the flat portion 35A when the first sheet 51 and the second sheet 52 are overlapped.

[0068] In the above second embodiment, both the first plate 51 and the second plate 52 have a configuration in which the flat portions 35A, 35B are circumferentially outside the radial direction of the yoke formation portion 31 (see Fig. 15A, Fig. 15B), but this may be changed. For example, in the first plate 51, the convex portion 34 is provided in a range from the innermost side of the yoke forming portion 31 in the radial direction to the outermost side of the yoke forming portion 31 in the radial direction (ie, the entire radial direction of the yoke forming portion 31). In this case, the second plate 52 is divided by the convex portion 34 of the first plate 51 and is overlapped with respect to the first plate 51 on either side of the circumferential direction of the convex portion 34.

[0069] In each of the above embodiments, the convex portion 34 is provided for each slot recess 33 in the core sheet 30, but this may be changed.

[0070] For example, the core sheet 30 may be configured with one convex portion 34 for each of the N ("N" is a natural number greater than or equal to 2) slot recesses 33 arranged in a row in the circumferential direction. Alternatively, the core sheet 30 may be configured with a plurality of convex portions 34 for each slot recess 33.

[0071] In each of the above embodiments, the yoke forming portion 31 of the core sheet 30 is configured with the convex portion 34 on the outer side of the slot recess 33 in the radial direction, but this may be changed. For example, a core sheet 30 as shown in Fig.17, is configured with convex portions 34 extending in the radial direction to be continuous at the yoke forming portion 31 and the tooth forming portion 32. In this configuration, in the core sheet 30, a convex portion 61 of the yoke is provided in the yoke forming portion 31, and a convex portion 62 of the teeth is provided in the tooth forming portion 32 as the convex portion 34. The convex portion 61 of the yoke and the convex portion 62 of the teeth are continuous in the radial direction. A space between the circumferentially adjacent convex yoke portions 61, that is, the radially outer side of the slot recess 33, is the flat portion 35. In such a configuration as above, the plate thicknesses of the convex portions 61, 62 and the flat portion 35 should be different, and the plate thicknesses of the convex portions 61, 62 should be smaller than that of the flat portion 35.

[0072] In each of the above embodiments, the stator core 11 has a spiral core structure in which the core sheets 30 are spirally stacked, but this may be changed. For example, a stator core 11 can be manufactured by preparing a number of core sheets 30 forming a circular ring and stacking the core sheets 30. In this case, each core sheet 30 should be circularly curved in the stacking direction and formed by the convex portion 34.

[0073] Stator cores can be used in external rotor type rotating electrical machines in addition to those used in internal rotor type rotating electrical machines. In one case, the stator core used in the external rotor type rotating electrical machine has teeth provided to project radially outward from the cylindrical back yoke. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2012-217279 A

[0002]

Claims

A stator core for a rotating electrical machine, comprising: a stator core (11) having a circular back yoke (21) and teeth (22) protruding from the back yoke in a radial direction of the stator core, wherein: the stator core is formed by multi-layer stacking core sheets, the core sheet has convex portions (34) provided at predetermined intervals in a circumferential direction and flat portions (35) provided between adjacent convex portions in the circumferential direction, each of the convex portions has a folded shape that is convex in a stacking direction and extends in the radial direction, the convex portions are stacked and overlap each other in the stacking direction, and a plate thickness of the convex portion is smaller than a plate thickness of the flat portion. The stator core for the rotating electric machine according to claim 1, wherein: thicknesses of the steel sheet material constituting the core sheet are different between the convex portions and the flat portions, a protrusion height of the convex portion on an inner side in the radial direction is greater than a protrusion height of the convex portion on an outer side in the radial direction, and the convex portion protrudes from the flat portion at a radially outermost position of the back yoke. A stator core for the rotating electric machine according to claim 2, wherein a concave surface portion on an opposite side of a convex surface portion of the convex portion is an inner convex portion (36), and a depth of the inner convex portion at a portion that is an outermost edge in the radial direction is equal to or greater than the plate thickness of the flat portion. The stator core for the rotating electric machine according to claim 2 or 3, wherein the convex portion has a triangular shape, an angle of a vertex of an inner portion of the convex portion in a radial direction of the back yoke is larger than an angle of a vertex of an outer portion of the convex portion in the radial direction, and a plate thickness of the outer portion is larger than a plate thickness of the inner portion. The stator core for the rotating electric machine according to claim 1, wherein:the core sheet includes a first sheet (51) having the convex portions and being continuous in the circumferential direction, and a second sheet (52) having a portion of the first sheet (51) except for the convex portions,the first sheet and the second sheet overlap with each other in the stacking direction, anda plate thickness of the convex portion is smaller than a plate thickness of the flat portion. The stator core for the rotating electric machine according to claim 5, wherein the plate thickness of the convex portion is equal to the plate thickness of a part of the first sheet other than the convex portions, and the plate thickness of the convex portion is smaller than the plate thickness of the flat portion. The stator core for the rotating electric machine according to claim 5 or 6, wherein the convex portions of the first sheet are provided in a range from an innermost edge in the radial direction to an intermediate position in the radial direction of the back yoke, and portions that are both sides of the convex portions in the circumferential direction of the second sheet are continuous at the outermost edge in the radial direction. The stator core for the rotating electric machine according to any one of claims 1 to 7, wherein the teeth of the stator core protrude inward from the back yoke in the radial direction of the stator core, and the convex portion has a flat shape on an upper surface in a predetermined range in the radial direction including an innermost edge in the radial direction. The stator core for the rotating electric machine according to any one of claims 1 to 7, wherein an end portion of at least one layer of the core sheets in the axial direction has a cut-out portion in at least an upper surface of the convex portion. The stator core for the rotating electric machine according to any one of claims 1 to 9, wherein the core sheet has a yoke forming portion (31) forming the back yoke and a tooth forming portion (32) forming the teeth, a rolled portion (41) is provided at an edge of the yoke forming portion in the radial direction opposite to the tooth forming portion, and a portion between the convex portions in the circumferential direction has a circular arc shape through the rolled portion in a plan view. The stator core for the rotating electrical machine according to any one of claims 1 to 9, wherein the core sheet has a yoke forming portion (31) forming the back yoke and a tooth forming portion (32) forming the teeth, a rolled portion (41) is provided at an edge of the yoke forming portion in the radial direction opposite to the tooth forming portion, the rolled portion (41) is provided at the edge except for the convex portions, and a portion between the convex portions in the circumferential direction has a circular arc shape through the rolled portion in a plan view.

Images