Rotor

Abstract

This invention provides a technology to suppress stress concentration in the magnet insertion holes of the rotor core, thereby suppressing deformation of the magnets. [Solution] A rotor core having a plurality of sets of pairs of magnet insertion holes on its outer circumference that extend in a V-shape outward in the radial direction, and a first magnet inserted in at least one of the pairs of magnet insertion holes, closest to the radially inward side of the rotor core along the direction extending radially outward, and a second magnet inserted radially outward at a distance from the first magnet, wherein the at least one magnet insertion hole has a projection on the inner wall of the rotor core radially inward in the gap between the first magnet and the second magnet that abuts or approaches the first magnet from the second magnet side and protrudes radially outward to hold the first magnet, and a concave portion on the second magnet side of the projection that is recessed radially inward.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a rotor.

Background Art

[0002] A rotor including a rotor core, a magnet inserted into a magnet insertion hole provided in the rotor core, and a molding material that holds the magnet in the magnet insertion hole is disclosed (Patent Document 1). In this rotor, a pair of magnet insertion holes extending so as to spread in a V shape toward the outer side in the radial direction are provided, and a plurality of magnets are accommodated in the magnet insertion holes extending in the radial direction, respectively, toward the outer side in the radial direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The magnet insertion hole includes a void filled with a molding material around the magnet inserted therein, and a protrusion or the like that abuts against the magnet for holding and positioning the magnet.

[0005] However, due to thermal stress during the manufacture of the rotor or centrifugal force during the rotation of the rotor, stress may concentrate on a specific part of the magnet insertion hole. In particular, when the rotor core or the magnet expands thermally, the magnet may be pushed toward the center bridge portion side of the magnet insertion hole, and stress may easily concentrate on the center bridge portion side of the magnet insertion hole. It is necessary to prevent the magnet from being deformed or broken due to such stress concentration.

[0006] This specification provides a technology for suppressing stress concentration in the magnet insertion hole of a rotor core and suppressing deformation of the magnet or the like. [Means for solving the problem]

[0007] The technology disclosed herein is embodied in a rotor. The rotor has a rotor core having a plurality of poles on its outer circumference, each of a pair of magnet insertion holes extending radially outward in a V-shape, and at least one of the pair of magnet insertion holes contains a first magnet inserted in the direction extending radially outward, closest to the radially inward side of the rotor core, and a second magnet inserted radially outward, spaced apart from the first magnet. The at least one magnet insertion hole has a projection on the radially inward inner wall of the rotor core in the gap between the first magnet and the second magnet, capable of contacting or approaching the first magnet from the second magnet side and projecting radially outward to hold the first magnet, and a concave portion on the second magnet side of the projection that is recessed radially inward.

[0008] According to the rotor, by providing the concave portion on the second magnet side of the projection, deformation of the projection is permitted in response to the force acting on the projection from the first magnet. As a result, the stress generated in at least one of the magnet insertion holes and the stress generated in the first magnet are suppressed. Consequently, deformation and breakage of the first magnet and other components are suppressed.

[0009] Conventionally, in magnet insertion holes, stress tended to concentrate on the side of the first magnet closer to the center bridge portion between the other magnet insertion hole of the pair of magnet insertion holes. However, by providing the concave portion on the second magnet side of the projection, it is possible to suppress the stress that tends to concentrate on the center bridge portion side between the projection and the concave portion. As a result, the stress on the center bridge portion side is reduced, and the stress on the center bridge portion side and the second magnet side of the first magnet can be balanced. As a result, deformation and damage to the first magnet and other components are suppressed as described above. [Brief explanation of the drawing]

[0010] [Figure 1]This is a cross-sectional view showing the magnet insertion holes and the magnet retention state in the rotor core of the rotor disclosed herein.

[0011] [Figure 2] This diagram schematically shows the state in which the magnet is held in the magnet insertion hole.

[0012] [Figure 3] This diagram shows the stress state in the magnet insertion hole. [Modes for carrying out the invention]

[0013] The rotor disclosed herein (hereinafter also referred to as "the rotor") may take the following forms in addition to the rotor described above.

[0014] In another embodiment of the rotor, the projection may have a wall-like portion that protrudes radially outward while being close to or in contact with the first magnet, the wall-like portion having a first surface that is close to or in contact with the first magnet and a second surface opposite to the first surface, and the concave portion may be formed with an inner surface shape that is recessed radially inward such that the second surface is substantially parallel to the first surface. In this way, the concave portion can be formed as close to the projection as possible. As a result, stress concentration around the first magnet can be suppressed more effectively in the concave portion.

[0015] Another embodiment of the rotor further comprises a retaining material positioned around the first and second magnets within at least one of the magnet insertion holes, wherein the concave portion has an inclined portion that moves away from the projection and slopes toward the second magnet. This ensures that when the retaining material containing resin is injected and filled into at least one of the magnet insertion holes, the resin can be reliably injected and filled into the concave portion as well. Having an inclined portion is advantageous when using a retaining material.

[0016] In another embodiment of the rotor, the at least one magnet insertion hole may further include one or more stress-relieving recesses around the first magnet to relieve the stress generated in the first magnet. This further suppresses the stress generated in the first magnet.

[0017] In another embodiment of this rotor, the stress-relieving recess may be provided so as to face the corner of the first magnet. This allows for effective stress relief at the corner.

[0018] Embodiments of the rotor core disclosed herein will be described below with reference to the drawings as appropriate. In this specification, "radial direction" refers to the radial direction of the rotor core, "circumferential direction" refers to the circumferential direction of the rotor core, and "axial direction" refers to the axial direction of the rotor core.

[0019] Furthermore, in this specification, the rotor is, for example, a motor-generator having the function of an electric motor or a generator. For example, the rotor can constitute a drive source for a vehicle or the like, either by itself or together with an internal combustion engine.

[0020] Figure 1 shows a cross-section of a portion of the rotor 2 disclosed herein, perpendicular to the axial direction of the rotor core 4. Figure 2 shows the holding state of the magnets 20a and 20b in the magnet insertion hole 12. Figure 3 shows the stress state on the magnets 20a, etc., in the magnet insertion hole 12. Figures 1 to 3 are cross-sectional views, but the hatches indicating the cross-sections have been omitted. In Figure 1, the retaining material 50 made of resin or the like for holding the magnets 20, etc., in the magnet insertion hole 12 has been omitted.

[0021] As shown in FIG. 1, the rotor 2 includes a rotor core 4 and a plurality of magnets 20 held within the rotor core 4. FIG. 1 shows a stator core 6 surrounding the rotor 2, a coil 8 provided in the stator core 6, and a frame 10 surrounding the outer periphery of the stator core 6. Also, a shaft (not shown) is held at the axial center of the rotor core 4 via a bearing 2a. The axial end faces and the other end faces of the rotor core 4 may be sandwiched by an end plate or the like (not shown).

[0022] The rotor core 4 is not particularly limited, but for example, it is formed of a laminated steel plate in which electromagnetic steel plates of a magnetic material such as iron or an iron alloy are laminated in the axial direction.

[0023] The rotor core 4 includes a plurality of sets of a pair of magnet insertion holes 12 and 14. More specifically, the rotor core 4 includes a plurality of sets of a pair of magnet insertion holes 12 and 14 that extend so as to widen in a V shape toward the outer side in the radial direction along the circumferential direction. For example, eight sets of a pair of magnet insertion holes 12 and 14 are provided. The magnet insertion holes 12 and 14 extend from the inner side to the outer side in the radial direction and respectively constitute the left and right sides of the V shape sandwiching the center bridge portion 15.

[0024] The V shape formed by the magnet insertion holes 12 and 14 is not particularly limited. The V shape may be configured to linearly widen from the inner side to the outer side in the radial direction, or may be formed to curve and widen as shown in FIG. 1.

[0025] The magnet insertion holes 12 and 14 are formed to penetrate the rotor core 4 in the axial direction. Two magnets 20 (hereinafter, referred to as 20a and 20b in order from the inner side in the radial direction) are held in each of the magnet insertion holes 12.

[0026] Here, we will describe the magnets 20a and 20b held by the magnet insertion hole 12. The magnets 20a and 20b are not particularly limited, but for example, known permanent magnets can be used. Each of the magnets 20a and 20b has an elongated shape that extends along the axial direction. In addition, the cross-section of the magnets 20a and 20b perpendicular to the axial direction has a quadrilateral shape, such as a rectangle, as shown in Figure 1. Note that the magnets 20a and 20b are examples of the first and second magnets disclosed herein.

[0027] The magnet insertion holes 12 and 14 shown in Figure 1 have a symmetrical configuration with the center bridge portion 15 in between them; therefore, the magnet insertion hole 12 will be described below.

[0028] Within the magnet insertion hole 12, as shown in Figures 1 and 2, the magnets 20a and 20b are arranged in order from the radially inner to the radially outer. More specifically, the elongated end faces corresponding to the long sides of the cross-sections of the magnets 20a and 20b are held along the radially outward extending direction of the magnet insertion hole 12. The magnets 20a and 20b are spaced apart within the magnet insertion hole 12 with a predetermined gap 18 between them. In Figure 1, since the magnet insertion hole 12 has a curved shape extending radially outward, the gap 18 has an inner surface shape that curves or bends between the two magnets 20a and 20b.

[0029] As shown in Figure 2, in the magnet insertion hole 12, a retaining material 50 is filled to fill the space between the magnets 20a, 20b and the inner wall surface of the magnet insertion hole 12. The retaining material 50 is not particularly limited, but it should have a certain degree of fluidity and be injected into the gap between the magnets 20a, etc., the magnet insertion hole 12 and the inner wall surface, and can be hardened by, for example, heat treatment to fill the gap. For example, the retaining material 50 may include a resin material such as a thermosetting resin or a thermoplastic resin.

[0030] The inner wall portion 16 of the magnet insertion hole 12 has a shape suitable for holding magnets 20a and 20b. As shown in Figure 2, the inner wall portion 16 of the magnet insertion hole 12 is provided with stress-relieving recesses 24, 26, 28, 30, and 32. All of the stress-relieving recesses 24, 26, 28, 30, and 32 are formed to extend along the axial direction.

[0031] The stress-relieving recesses 24, 26, and 28 are provided around the magnet 20a to relieve stress caused by thermal stress and centrifugal force. Thermal stress may occur during the manufacturing of the rotor 2, such as during the injection and heat treatment of the retaining material 50 and the welding of the laminated steel plates of the rotor core 4. Centrifugal force may also occur during the rotation of the rotor 2.

[0032] The stress-relieving recess 24 is formed proximal to the center bridge portion 15 of the magnet 20a and opposite the long end face near the radially outer corner L1. The stress-relieving recess 26 is formed opposite the short end face corresponding to the short side L2, which is located most radially inward of the magnet 20a. Between the stress-relieving recess 24 and the stress-relieving recess 26, a holding portion 25 is formed that abuts against or is close to the short end face near the corner L1 of the magnet 20a, enabling the holding and positioning of the magnet 20a.

[0033] The stress-relieving recess 28 is located distal to the center bridge portion 15 of the magnet 20a and is formed opposite the elongated end face near the radially inward corner L3. The stress-relieving recesses 24, 26, and 28 are all formed in a concave shape toward the interior of the rotor core 4, forming a gentle curved surface, and are configured to relieve stress around the magnet 20a.

[0034] The stress-relieving recesses 30 and 32 are provided around the magnet 20b to relieve stress caused by the various factors described above. The stress-relieving recess 30 is formed distal to the center bridge portion 15 of the magnet 20b and faces the long end face near the radially inward corner L4. The stress-relieving recess 32 is formed facing the short end face corresponding to the short side L5, which is the most radially outermost part of the magnet 20b. Both the stress-relieving recesses 30 and 32 are formed in a concave shape toward the inside of the rotor core 4, forming a gentle curved surface, and are configured to relieve stress around the magnet 20b.

[0035] As shown in Figures 1 and 2, the gap 18 between magnet 20a and magnet 20b is provided with a projection 34 capable of holding magnet 20a. The projection 34 is formed on the inner wall portion 18a on the radially inner side of the gap 18. The projection 34 includes a wall-like portion 35 that can hold and position magnet 20a by contacting or approaching a short end face L6 within a predetermined range from the corner L3 of magnet 20a from the radially outer side or the magnet 20b side.

[0036] The wall-like portion 35 comprises a surface 36 facing the short end face L6 and a surface 38 opposite to surface 36. Surface 38 is exposed to the magnet 20b side in the gap 18. Surfaces 36 and 38 are generally parallel, and the wall-like portion 35 is a wall-like body of generally constant thickness. The height and thickness of the wall-like portion 35 only need to be sufficient to function as a projection 34; for example, its thickness can be in the range of 0.3 mm to 2 mm. Surfaces 36 and 38 are examples of the first and second surfaces disclosed herein, respectively.

[0037] The magnet insertion hole 12 is provided with a concave portion 40. The concave portion 40 is provided adjacent to the magnet 20b side of the projection 34. In the magnet insertion hole 12, the concave portion 40 is formed to be recessed radially inward from the inner wall portion 18a, that is, away from the projection 34 and the inner wall portion 18a.

[0038] Unlike the stress-relieving recesses 24, 26, 28, 30, and 32, the concave portion 40 is not a greatly curved concave shape, but is generally formed as a narrow groove. This effectively allows deformation of the projection 34 and suppresses stress concentration around the magnet 20a. For example, as shown in Figure 2, the concave portion 40 is formed with an inner surface shape such that a surface 38, which is generally parallel to the surface 36 of the wall-like portion 35, is recessed radially inward. This allows the concave portion 40 to be formed as close as possible to the projection 34. This effectively allows deformation of the projection 34 and effectively reduces stress concentration generated around the magnet 20a by the concave portion 40.

[0039] As shown in Figures 1 and 2, the concave portion 40 is provided with an inclined portion 42 that moves away from the projection 34 and inclined toward the magnet 20b. The inclined portion 42 is inclined to enlarge the opening of the concave portion 40 toward the magnet 20b. This makes it easier to fill the concave portion 40 with the retaining material 50 when injecting it.

[0040] The shape and size of the recess in the concave portion 40 are not particularly limited, but should be such that they allow deformation of the projection 34 and suppress stress concentration around the magnet 20a. For example, the inner wall portion 18a can be made to have a groove-like opening in a width of approximately 0.3 mm to 2 mm.

[0041] Furthermore, the rotor core 4 may have an additional pair of magnet insertion holes 60, 62 and magnets located radially outward from the V-shaped interior of the magnet insertion holes 12, 14. In addition, the radial interior of the magnet insertion holes 12, 14 may have a suitable number of refrigerant flow paths 70, 72 along the circumferential direction.

[0042] The stress concentration suppression effect in the magnet insertion hole 12 of the rotor 2 will now be explained. The upper part of Figure 3 shows the state inside the magnet insertion hole 12' having the same configuration as above except that it does not have the concave portion 40, and the lower part of Figure 3 shows the state inside the magnet insertion hole 12 having the concave portion 40.

[0043] As shown in the upper part of Figure 3, in the conventional magnet insertion hole 12', stresses originating from the various factors described above tended to concentrate near the short end face corresponding to the short side L2 of the magnet 20a.

[0044] In contrast, as shown in the lower part of Figure 3, the rotor core 4, which has a concave portion 40, has a concave portion 40 that acts as a kind of weak point, allowing deformation of the protrusion 34. By allowing deformation of the protrusion 34, for example, when the rotor core 4 and the magnet 20a undergo thermal expansion, the amount of displacement of the short side L2 of the magnet 20a toward the center bridge portion 15 is suppressed. Therefore, the stress near the short end face corresponding to the short side L2 of the magnet 20a can be reduced. As a result, stress concentration around the magnet 20a is suppressed, and deformation of the magnet 20a can be suppressed. At the same time, since stress concentration on the center bridge portion 15 is suppressed, the center bridge portion 15 can be made narrower, and the maximum rotational speed of the rotor 2 can be increased.

[0045] In the above embodiment, the concave portion 40 is formed in a groove shape on the magnet 20b side adjacent to the projection 34 that holds the magnet 20a, so that deformation of the projection 34 can be effectively tolerated and stress concentration around the magnet 20a can be more effectively suppressed. Furthermore, in the above embodiment, the magnet insertion holes 12 and 14 of the rotor 2 are each configured similarly, but some of the magnet insertion holes 12 and 14 of the rotor 2, or at least one of the magnet insertion holes 12 and 14, may be provided with the concave portion 40.

[0046] Furthermore, because the concave portion 40 of the rotor core 4 is equipped with an inclined portion 42, when the retaining material 50 made of resin material is injected around the magnet 20a and the like and hardened, the retaining material 50 is more easily filled into the concave portion 40, thereby improving the filling performance of the retaining material 50.

[0047] In addition to the concave portion 40, the rotor core 4 is also equipped with stress-relieving recesses 24, 26, 28, 30, and 32 in the magnet insertion hole 12, so that stresses that occur under various conditions can be distributed within the rotor core 4.

[0048] In the embodiments described above, the concave portion 40 is formed with an inner surface shape such that a surface 38, which is generally parallel to the surface 36 of the wall-like portion 35, is recessed radially inward. However, the embodiment is not limited to this. The concave portion 40 may have an inner surface shape in which the surface 38 is inclined to gradually move away from the top of the wall-like portion 35 and recesses radially inward.

[0049] Furthermore, although the above embodiments include stress-relieving recesses 24, 26, 28, 30, and 32, at least some of these may be included. The configuration of the stress-relieving section can be changed as needed.

[0050] Furthermore, although the above embodiments use a retaining material 50 containing a resin material, the invention is not limited to this. Various other known retaining means can be used as appropriate.

[0051] Based on the above description, this specification includes the following items. [1] A rotor, A rotor core having multiple sets of a pair of magnet insertion holes on its outer circumference that extend radially outward in a V-shape, In at least one of the pair of magnet insertion holes, a first magnet is inserted in a direction extending radially outward, closest to the radially inward side of the rotor core, and a second magnet is inserted radially outward, spaced apart from the first magnet. Equipped with, The rotor wherein at least one of the magnet insertion holes includes a projection on the inner wall of the rotor core radially inward of the gap between the first magnet and the second magnet, which can contact or approach the first magnet from the second magnet side and project radially outward to hold the first magnet, and a recessed portion on the second magnet side of the projection that is recessed radially inward. [2] The projection has a wall-like portion that protrudes radially outward while being close to or in contact with the first magnet, and the wall-like portion has a first surface that is close to or in contact with the first magnet, and a second surface opposite to the first surface, The rotor according to [1], wherein the concave portion is formed having an inner surface shape that is recessed radially inward such that the second surface is substantially parallel to the first surface. [3] Furthermore, the device comprises a retaining material positioned around the first magnet and the second magnet within at least one of the magnet insertion holes, The rotor according to [1] or [2], wherein the concave portion has an inclined portion that moves away from the projection and inclined toward the second magnet. [4] The rotor according to any one of [1] to [3], wherein at least one of the magnet insertion holes further comprises one or more stress-relieving recesses around the first magnet for relieving stress generated in the first magnet. [5] The rotor according to [4], wherein the stress-relieving recess is provided so as to be opposite to the corner of the first magnet.

[0052] The specific examples of the technology disclosed in this specification have been described in detail above, but these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples described above. The technical elements described in this specification or in the 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. The technology illustrated in this specification or in the drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives itself constitutes technical usefulness. [Explanation of symbols]

[0053] 2 rotor, 4 rotor core, 6 stator core, 8 coil, 12, 14 magnet insertion hole, 15 center bridge section, 16 inner wall section, 18 gap, 18a inner wall section, 20, 20a, 20b magnet, 24, 26, 28, 30, 32 stress relief recess, 34 projection, 35 wall-like section, 40 concave section, 42 inclined section, 50 retaining material, L1, L3, L4 corner section, L2, L5 short side, L6 short end face

Claims

1. It is a rotor, A rotor core having multiple sets of a pair of magnet insertion holes on its outer circumference that extend radially outward in a V-shape, In at least one of the pair of magnet insertion holes, a first magnet is inserted in a direction extending radially outward, closest to the radially inward side of the rotor core, and a second magnet is inserted radially outward, spaced apart from the first magnet. Equipped with, The rotor wherein at least one of the magnet insertion holes includes a projection on the inner wall of the rotor core radially inward of the gap between the first magnet and the second magnet, which can abut or approach the first magnet from the second magnet side and protrude radially outward to hold the first magnet, and a concave portion on the second magnet side of the projection that is recessed radially inward.

2. The projection has a wall-like portion that protrudes radially outward while being close to or in contact with the first magnet, and the wall-like portion has a first surface that is close to or in contact with the first magnet, and a second surface opposite to the first surface. The rotor according to claim 1, wherein the concave portion is formed having an inner surface shape that is recessed radially inward such that the second surface is substantially parallel to the first surface.

3. Furthermore, the device includes a retaining material positioned around the first magnet and the second magnet within at least one of the magnet insertion holes, The rotor according to claim 1, wherein the concave portion has an inclined portion that is separated from the projection and inclined toward the second magnet.

4. The rotor according to any one of claims 1 to 3, wherein the at least one magnet insertion hole further comprises one or more stress-relieving recesses around the first magnet for relieving stress generated in the first magnet.

5. The rotor according to claim 4, wherein the stress-relieving recess is provided so as to face the corner of the first magnet.

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