Stator core

Abstract

To properly prevent damage to the stator core. [Solution] The stator core for a rotating electric machine comprises a core portion and a plurality of first fixing portions. The core portion has a cylindrical shape centered on a central axis. The core portion comprises a plurality of electromagnetic steel sheets stacked in an axial direction parallel to the central axis. The plurality of first fixing portions are arranged along the outer circumferential surface of the core portion, and each has a through hole parallel to the central axis. Each of the plurality of first fixing portions is made of a separate material from the core portion and is fixed to the outer circumferential surface.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a stator core for a rotating electrical machine.

[0002] Patent Document 1 discloses a stator core for a rotating electrical machine. The stator core includes a fixing portion that protrudes radially outward from the outer periphery. The stator core and the fixing portion are formed by laminating electromagnetic steel sheets. That is, the fixing portion is integrally formed with the stator core. The fixing portion is provided with bolt holes that penetrate axially therethrough. By passing bolts through the bolt holes and fastening them, the stator core can be fixed to the case.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An external force is applied to the electromagnetic steel sheets constituting the fixing portion by bolts. Due to this external force, damage such as warping may occur in the electromagnetic steel sheets constituting the fixing portion. Since the fixing portion and the stator core are composed of electromagnetic steel sheets of the same member, there is a risk that the damage generated in the fixing portion will propagate to the stator core side through the electromagnetic steel sheets.

Means for Solving the Problems

[0005] The stator core for a rotating electric machine disclosed herein comprises a core portion and a plurality of first fixing portions. The core portion has a cylindrical shape with respect to a central axis. The core portion comprises a plurality of electromagnetic steel sheets stacked in an axial direction parallel to the central axis. The plurality of first fixing portions are arranged along the outer circumferential surface of the core portion, and each has a through hole parallel to the central axis. Each of the plurality of first fixing portions is made of a separate material from the core portion and is fixed to the outer circumferential surface.

[0006] In the above configuration, the first fixing part is made of a separate component from the core part. This prevents the damage to the first fixing part from propagating to the core part even if damage occurs to the first fixing part due to various external forces. This makes it possible to suppress damage to the electromagnetic steel sheet that makes up the core part. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic top view of the stator core 10. [Figure 2] This is an enlarged top view of region II in Figure 1. [Figure 3] This is a schematic side view taken from the direction of arrow Y3 in Figure 1. [Figure 4] This is a schematic cross-sectional view along the line IV-IV in Figure 1. [Figure 5] This is a schematic top view of the stator core 110 of the comparative example. [Figure 6] This figure shows a modified example of the welded joint 22. [Figure 7] This is an enlarged top view of the stator core 210 of Example 2. [Figure 8] This is an enlarged top view showing a modified example of Example 2. [Figure 9] This is an enlarged top view of the stator core 310 of Example 3. [Figure 10] This is an enlarged top view of the stator core 410 of Example 4. [Modes for carrying out the invention]

[0008] Each of the multiple first fixing parts may be welded to the outer circumferential surface of the core part at least a portion of a pair of sides extending in the axial direction from the periphery of the contact surface with the outer circumferential surface of the core part.

[0009] According to the above configuration, each of the multiple first fixing parts can be securely fixed to the outer surface of the core part by welding.

[0010] In each of the multiple first fixing parts, a weld may be formed over the entire length of a pair of sides.

[0011] According to the above configuration, the first fixing portion can be fixed to the outer circumferential surface of the core portion along the entire length of a pair of sides.

[0012] In each of the multiple first fixing parts, welds may be formed in a staggered pattern on a pair of sides.

[0013] According to the above configuration, the overall length of the weld can be shortened while maintaining the weld strength. Eddy current losses caused by the weld can be suppressed.

[0014] The core portion may have a plurality of grooves formed on its outer circumferential surface and extending in the axial direction. The plurality of first fixing portions may have projections formed on their contact surfaces with the outer circumferential surface, protruding from the contact surface and extending in the axial direction. The grooves and projections may be engaged with each other.

[0015] According to the above configuration, a fitting structure can be formed by the groove and the projection. This makes it possible to increase the attachment strength of the first fixing part to the core part.

[0016] The core portion may include a base portion formed on its outer surface and protruding radially outward from the outer surface. The groove portion may be formed on the base portion.

[0017] A high stress is applied to the base portion in a direction to expand the groove portion by the protruding portions that are fitted together. According to the above configuration, the stress can be suppressed from being transmitted to the core portion due to the protrusion of the base portion. It becomes possible to prevent the deterioration of losses.

[0018] The circumferential width of the groove portion may be larger on the radially inner side than on the radially outer side. The circumferential width of the protruding portion may be larger on the radially inner side than on the radially outer side.

[0019] According to the above configuration, due to the tapered shape of the groove portion and the protruding portion, a return structure can be provided. It is possible to prevent the protruding portion from coming out of the groove portion.

[0020] The plurality of first fixing portions may be arranged at equal intervals in the circumferential direction centered on the central axis.

[0021] The core portion may further include a plurality of second fixing portions that are arranged along the outer peripheral surface of the core portion and each have a through hole parallel to the central axis. Each of the plurality of second fixing portions may protrude radially outward from the outer peripheral surface and may be integrally formed with the core portion.

[0022] According to the above configuration, by mixing the first fixing portion separate from the core portion and the second fixing portion integral with the core portion, the total number of fixing portions can be arbitrarily varied.

[0023] [[ID=2—4]]The core portion may include a plurality of core blocks arranged along the axial direction. Each of the plurality of core blocks may include a plurality of electromagnetic steel sheets laminated in the axial direction. Each of the plurality of core blocks may include a plurality of caulked portions that caulked the plurality of electromagnetic steel sheets together and are arranged along the circumferential direction centered on the central axis. The circumferential distance between adjacent first fixing portions and caulked portions may be larger than the circumferential distance between adjacent caulked portions and caulked portions.

[0024] With the above configuration, the first fixing part can provide the same function as the crimping part. Therefore, it becomes possible to omit the crimping part in the vicinity of the first fixing part. This makes it possible to reduce losses caused by the crimping part. [Examples]

[0025] (Structure of stator core 10) Figure 1 shows a schematic top view of a stator core 10 for a rotating electric machine according to this embodiment. In Figure 1, the z direction is the direction in which the central axis CA extends. The x and y directions are directions in a plane perpendicular to the central axis CA. The coordinate relationship is the same in subsequent figures. Figure 2 shows an enlarged top view of region II in Figure 1. Figure 3 shows a schematic side view seen from the direction of arrow Y3 in Figure 1. For the purpose of clarity in the illustration, only one of the repeatedly arranged components may be labeled with a reference numeral.

[0026] The stator core 10 comprises a core portion 20 and a plurality of first fixing portions 21. The core portion 20 is a cylindrical member with a central axis CA. The core portion 20 has a cylindrical back yoke 20y. A plurality of convex teeth 20a are provided on the inner circumferential surface of the back yoke 20y. Slot portions SL are formed between adjacent teeth 20a.

[0027] As shown in Figure 3, the core portion 20 comprises a plurality of core blocks 20B arranged along the axial direction (z-direction) parallel to the central axis CA. Each of the plurality of core blocks 20B comprises a plurality of electrical steel sheets 25 stacked in the axial direction.

[0028] As shown in Figure 1, each of the multiple core blocks 20B is provided with multiple crimping portions CR. The multiple crimping portions CR are arranged along the circumferential direction with respect to the central axis CA. The multiple crimping portions CR are the parts that integrate the multiple electromagnetic steel sheets 25 constituting the core block 20B by crimping them together. The circumferential distance between adjacent first fixing portions 21 and crimping portions CR is distance D1. The circumferential distance between adjacent crimping portions CR is distance D2. Distance D1 is greater than distance D2.

[0029] Multiple first fixing parts 21 are arranged along the outer circumferential surface 20s of the core part 20. The multiple first fixing parts 21 are arranged at equal intervals in the circumferential direction with respect to the central axis CA. In the example shown in Figure 1, three first fixing parts 21 are arranged with 120-degree rotational symmetry.

[0030] Each of the multiple first fixing parts 21 is provided with a through hole 21h parallel to the central axis CA. Each of the multiple first fixing parts 21 is made of a separate material from the core part 20. Note that all of the multiple first fixing parts 21 have the same structure. Therefore, in the following description, a representative first fixing part 21 may be described.

[0031] As shown in Figures 2 and 3, the core portion 20 is provided with a plurality of grooves 20t formed on its outer circumferential surface 20s. The grooves 20t extend in the axial direction (z-direction) of the central axis CA. The first fixing portion 21 is provided with a contact surface 21c and a projection 21p. The contact surface 21c is the surface that contacts the outer circumferential surface 20s of the core portion 20. The projection 21p is formed on the contact surface 21c. The projection 21p protrudes from the contact surface 21c and extends in the axial direction. The projection 21p engages with the grooves 20t of the core portion 20. As a result, the first fixing portion 21 and the core portion 20 are mechanically joined by a fitting structure.

[0032] The contact surface 21c of the first fixing portion 21 is provided with a peripheral edge 21r. A welded portion 22 is formed on the entirety of a pair of axially extending sides of the peripheral edge 21r. The welded portion 22 is a bead formed on the metal parts joined by welding.

[0033] (Mounting structure of stator core 10) Figure 4 shows a schematic cross-sectional view along the line IV-IV in Figure 1. Figure 4 is a cross-sectional view passing through the central axis CA, the slot SL, and the through hole 21h. Figure 4 shows the state in which the coil 30 is wound around the stator core 10. Figure 4 also shows the state in which the stator core 10 is fixed to the case 50 by bolts 40. The stator core 10 has a structure that is rotationally symmetric with respect to the central axis CA. Therefore, Figure 4 only describes the structure on the -y direction side with respect to the central axis CA.

[0034] A first end face 10e1 is formed at one end of the stator core 10 in the axial direction (z-direction), and a second end face 10e2 is formed at the other end. A winding constituting a coil 30 is wound around the stator core 10. The first coil end 30e1 of the coil 30 protrudes axially from the first end face 10e1. The second coil end 30e2 of the coil 30 protrudes axially from the second end face 10e2.

[0035] A first fixing portion 21 is fixed to the outer circumferential surface 20s of the core portion 20. The first fixing portion 21 extends from the first end face 10e1 to the second end face 10e2. The through hole 21h extends along the axial direction (z direction) and penetrates the first fixing portion 21. A bolt 40 is inserted through the through hole 21h. The stator core 10 is fastened to the case 50 by the bolt 40.

[0036] (assignment) The problem will be explained using the stator core 110 of the comparative example shown in Figure 5. Figure 5 is a drawing of the same aspect as Figure 4. The stator core 110 of the comparative example (Figure 5) differs from the stator core 10 of this embodiment (Figure 4) in the structure of the first fixing portion 121. Specifically, the first fixing portion 121 of the comparative example is constructed by laminating electromagnetic steel sheets 25. That is, in the comparative example (Figure 5), the first fixing portion 121 is formed integrally with the core portion 120. On the other hand, in this embodiment (Figure 4), the first fixing portion 21 is made of a separate material from the core portion 20.

[0037] BEVs (Battery Electric Vehicles) and large vehicles require motors with high torque and high output. Such motors tend to have a stator core thickness (thickness in the lamination direction of the electromagnetic steel sheets) that increases. In a structure in which the stator core is fixed to the case 50 using bolts 40, the bolt axial force is the source of the fixing force. In this structure, as the stator core thickness increases, there is a risk that the bolts will loosen due to wear over time. If the bolts are fixed with a high axial force to reduce this risk, damage may occur to the electromagnetic steel sheets 25 that make up the seating surface of the first fixing part 121 due to seating surface friction (see Figure 5, region R1). Examples of damage include peeling of the surface of the electromagnetic steel sheets 25 and indentation of the seating surface.

[0038] In the comparative example, since the first fixing part 121 and the core part 120 are made of the same electromagnetic steel sheet 25, there is a risk that damage occurring in the first fixing part 121 may propagate to the core part 120 side via the electromagnetic steel sheet 25 (see arrow Y1). As a result, there is a risk that the magnetic properties of the back yoke of the core part 120 will deteriorate.

[0039] (effect) In the stator core 10 of this embodiment (Figure 4), the first fixing portion 21 is made of a separate component from the core portion 20. As a result, even if damage occurs to the seating surface of the first fixing portion due to bolt axial force, as shown in region R2, it is possible to prevent the damage from propagating to the core portion 20. Since damage to the electromagnetic steel sheet 25 constituting the core portion 20 can be suppressed, the magnetic properties of the back yoke of the core portion 20 can be maintained in good condition.

[0040] As shown in Figure 2, a fitting structure is formed by the groove 20t and the projection 21p. This makes it possible to improve the positioning accuracy when attaching the first fixing part 21 to the core part 20. In addition, compared to the case without a fitting structure, the attachment strength of the first fixing part 21 to the core part 20 can be increased, making it possible to increase the allowable stress when irregular torque loads are applied.

[0041] The first fixing portion 21 allows the electromagnetic steel sheets 25 constituting the core portion 20 to be integrated with each other. In other words, the first fixing portion 21 can provide the same function as the crimping portion CR. This makes it possible to omit the crimping portion CR in the vicinity of the first fixing portion 21. In other words, as shown in Figure 2, the distance D1 between the first fixing portion 21 and the crimping portion CR can be made larger than the distance D2 between two crimping portions CR. This makes it possible to reduce the number of crimping portions CR while maintaining the fixing force that integrates the electromagnetic steel sheets 25. The crimping portion CR is an element that obstructs the magnetic path of the back yoke portion of the core portion 20. Since this element can be reduced, it is possible to obtain a loss reduction effect. Furthermore, if the fixing force required for the electromagnetic steel sheets 25 can be met by the first fixing portion 21 alone, it is possible to eliminate all crimping portions CR.

[0042] (Modified version of Example 1) The welded portion 22 only needs to be formed on at least a portion of a pair of axially extending edges of the periphery 21r. Therefore, the welded portion 22 can have various shapes. Figure 6 shows a modified example of the welded portion 22. Figure 6 is a drawing of the same embodiment as Figure 3. In Figure 6, the welded portion 22 is formed in a staggered pattern on a pair of axially extending edges. That is, the welded portions 22 are alternately arranged on the right and left edges of the pair of edges. In the staggered arrangement, when the welded portions 22 on the right edge and the welded portions 22 on the left edge are added together, the welded portion 22 is arranged over the entire axial direction. This makes it possible to shorten the total length of the welded portion 22 per edge. In other words, in the staggered arrangement, the total length of the welded portion 22 can be shortened while maintaining the welding strength. In the welded portion 22, the electrical connection is made between the electromagnetic steel sheets that were previously insulated by the coating, so there is a risk that eddy current loss will worsen. Therefore, by using a staggered arrangement, the overall length of the welded section 22 can be shortened while maintaining welding strength, thereby suppressing eddy current loss.

[0043] The structure may not include a fitting structure with a projection 21p and a groove 20t. In other words, the first fixing part 21 may be fixed to the core part 20 only by a welded part 22. [Examples]

[0044] (Configuration of base section 220b) Figure 7 shows an enlarged top view of the stator core 210 of Example 2. Figure 7 is a drawing showing the same area as in Figure 2. Example 2 differs from Example 1 in that it has a base portion 220b. Components common to Example 2 and Example 1 are given the same reference numerals, and their explanation is omitted. Components unique to Example 2 are distinguished by their reference numerals in the 200s.

[0045] The core portion 20 includes a base portion 220b which is integrally formed with the core portion 20. The base portion 220b is formed on the outer peripheral surface 20s and protrudes radially outward from the outer peripheral surface 20s. The base portion 220b includes a base portion contact surface 220c. The base portion contact surface 220c is the surface that contacts the contact surface 21c of the first fixing portion 21. The base portion contact surface 220c protrudes outward from the outer peripheral surface 20s by a distance D3.

[0046] A groove 220t is formed in the base portion 220b. The projection 21p of the first fixing portion 21 is press-fitted into the groove 220t. As a result, the first fixing portion 21 and the base portion 220b are mechanically joined by a fitting structure. Furthermore, no welded joint is formed on the periphery 21r of the first fixing portion 21. In other words, the first fixing portion 21 is fixed to the core portion 20 solely by the press-fitting method.

[0047] (effect) A high stress ST is applied to the base portion 220b by the press-fitted projection 21p, which widens the groove portion 220t. When this stress ST is transmitted to the back yoke 20y of the core portion 20, the permeability of the back yoke 20y decreases due to the reverse magnetostrictive effect. Therefore, in the technology of Example 2, the base portion 220b is made to protrude radially outward from the outer surface 20s by a distance D3. As a result, the protruding base portion 220b can absorb the stress ST. In other words, the transmission of stress ST to the core portion 20 can be suppressed by the base portion 220b. This suppresses the deterioration of the magnetic properties of the back yoke 20y, and thus prevents the deterioration of losses.

[0048] (Modified version of Example 2) Figure 8 shows a modified example of the base portion 220b. Figure 8 is a drawing showing the same region as in Figure 7. In the modified example of Figure 8, the groove portion 220t has a tapered shape such that the width at the bottom of the groove is wider than the width at the entrance of the groove. Specifically, the groove portion 220t has a width W1 on the radially inner side, which is the bottom of the groove. Also, the groove portion 220t has a width W2 on the radially outer side, which is the entrance of the groove. Width W1 is greater than width W2. Furthermore, the projection portion 21p of the first fixing portion 21 has a shape corresponding to the tapered shape of the groove portion 220t. Specifically, the projection portion 21p has a width W1 on the radially inner side, which is the tip of the projection. Also, the projection portion 21p has a width W2 on the radially outer side, which is the base of the projection.

[0049] The tapered shape of the groove 220t and projection 21p creates a so-called return structure. This prevents the projection 21p from coming out of the groove 220t. This makes it possible to fix the first fixing part 21 and the core part 20 more firmly.

[0050] In a structure in which the first fixing part 21 is fixed to the core part 20 by a press-fitting method, a welded part may also be formed. [Examples]

[0051] (Structure of stator core 310) Figure 9 shows an enlarged top view of the stator core 310 of Example 3. Figure 9 is a drawing showing the same area as in Figure 1. Example 3 differs from Example 1 in the arrangement of the fixed parts. Components common to Example 3 and Example 1 are given the same reference numerals, and their explanation is omitted. Components unique to Example 3 are distinguished by their reference numerals in the 300s.

[0052] The stator core 310 of Example 3 (Figure 9) has a configuration that adds a plurality of second fixing portions 332 to the stator core 10 of Example 1 (Figure 1). The plurality of second fixing portions 332 are arranged along the outer peripheral surface 20s of the core portion 20. The plurality of second fixing portions 332 are arranged at equal intervals in the circumferential direction with respect to the central axis CA. In the example of Figure 9, three second fixing portions 332 are arranged with 120-degree rotational symmetry. Each of the plurality of second fixing portions 332 has a through hole 332h parallel to the central axis CA. The plurality of second fixing portions 332 are constructed by laminating electromagnetic steel sheets 25. That is, the plurality of second fixing portions 332 are formed integrally with the core portion 20.

[0053] (effect) By combining a first fixing part 21 separate from the core part 20 and a second fixing part 332 integrated with the core part 20, the total number of fixing parts can be arbitrarily varied. In other words, a configuration with only the second fixing part 332 can be used as the basic structure. Then, according to the need to increase the fixed axial force, the first fixing part 21 can be added. The higher the required fixed axial force, the more first fixing parts 21 should be added. This makes it possible to flexibly change the total number of fixing parts according to the fixed axial force needs. [Examples]

[0054] (Structure of the stator core 410) Figure 10 shows an enlarged top view of the stator core 410 of Example 4. Figure 10 is a drawing showing the same area as in Figure 1. Components common to Example 4 and Example 1 are given the same reference numerals, and their explanation is omitted. Components unique to Example 4 are distinguished by their reference numerals in the 400s.

[0055] In the stator core 410 of Embodiment 4, the multiple first fixing parts 21 are arranged at unequal intervals in the circumferential direction with respect to the central axis CA. That is, there are two types of circumferential distances between adjacent first fixing parts 21: distance D11 and distance D12.

[0056] Since the first fixing part 21 is a separate component from the core part 20, it offers greater flexibility in its mounting position. Therefore, the position of the first fixing part 21 can be appropriately adjusted according to the mounting constraints of the stator core 410. This increases the mounting flexibility of the stator core 410. Note that the arrangement of the first fixing part 21 in Figure 10 is just one example. In reality, there are various variations in the arrangement of the first fixing part 21.

[0057] Although embodiments have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness. [Explanation of Symbols]

[0058] 10: Stator core 20: Core section 20s: Outer surface 21: First fixing section 21h: Through hole 22: Welded section 25: Electrical steel sheet CA: Central axis

Claims

1. The core portion has a cylindrical shape centered on a central axis and comprises a plurality of electromagnetic steel sheets stacked in an axial direction parallel to the central axis, A plurality of first fixing parts are arranged along the outer circumferential surface of the core portion, each having a through hole parallel to the central axis, A stator core for a rotating electric machine, comprising: Each of the plurality of first fixing parts is made of a separate material from the core part and is fixed to the outer surface. Stator core.

2. The stator core according to claim 1, wherein each of the plurality of first fixing portions is welded to the outer circumferential surface of the core portion at least a portion of a pair of sides extending in the axial direction from the periphery of the contact surface with the outer circumferential surface of the core portion.

3. The stator core according to claim 2, wherein a welded portion is formed over the entire length of the pair of sides in each of the plurality of first fixing portions.

4. The stator core according to claim 2, wherein in each of the plurality of first fixing portions, welded portions are formed in a staggered pattern on the pair of sides.

5. The core portion is provided with a plurality of grooves formed on the outer circumferential surface and extending in the axial direction, The plurality of first fixing portions are formed on the contact surface with the outer peripheral surface and have projections that protrude from the contact surface and extend in the axial direction. The stator core according to any one of claims 1 to 4, wherein the groove and the projection are engaged.

6. The core portion includes a base portion formed on the outer circumferential surface and protruding radially outward from the outer circumferential surface, The stator core according to claim 5, wherein the groove portion is formed in the base portion.

7. The circumferential width of the groove is greater on the radially inner side than on the radially outer side. The stator core according to claim 5, wherein the circumferential width of the projection is greater on the radially inner side than on the radially outer side.

8. The stator core according to claim 1, wherein the plurality of first fixing portions are arranged at equal intervals in the circumferential direction with respect to the central axis.

9. The core portion further comprises a plurality of second fixing portions arranged along the outer circumferential surface of the core portion, each having a through hole parallel to the central axis. The stator core according to claim 1, wherein each of the plurality of second fixing portions protrudes radially outward from the outer peripheral surface and is integrally formed with the core portion.

10. The core portion comprises a plurality of core blocks arranged along the axial direction, Each of the aforementioned multiple core blocks comprises multiple electrical steel sheets stacked in the axial direction, Each of the aforementioned multiple core blocks comprises a plurality of crimping portions that crimp the plurality of electromagnetic steel sheets together, the plurality of crimping portions arranged along the circumferential direction with respect to the central axis, The stator core according to claim 1, wherein the circumferential distance between adjacent first fixing portions and crimped portions is greater than the circumferential distance between adjacent crimped portions and crimped portions.

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