Rotor manufacturing method

Abstract

The present invention provides a method for manufacturing a rotor in which permanent magnets can be stably bonded to the rotor core. [Solution] The rotor manufacturing method according to the present disclosure comprises a rotor core 10, a plurality of magnet insertion holes 12 that penetrate the rotor core 10 in the axial direction and are arranged along the circumferential direction of the rotor core 10, permanent magnets 20 inserted into the magnet insertion holes 12, and an adhesive 30 interposed between the inner wall of the magnet insertion holes 12 and the permanent magnets 20, wherein the adhesive 30 is applied to the permanent magnets 20 before inserting them into the magnet insertion holes 12, the permanent magnets 20 are aligned within the magnet insertion holes 12 with an external magnetic field applied, and the magnetic force F2 acting on the permanent magnets 20 by the external magnetic field acts in the opposite direction to the attractive force F1 that pulls the permanent magnets 20 towards the rotor core 10 within the magnet insertion holes 12.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a rotor.

Background Art

[0002] Motors have been proposed that rotate a rotor more efficiently by embedding permanent magnets in a rotor core and utilizing the magnet torque generated by the permanent magnets and the reluctance torque generated by the rotor core. The permanent magnets are inserted into magnet insertion holes formed in the rotor core and fixed to the rotor core with an adhesive.

[0003] The magnet insertion holes are designed such that the gap with the permanent magnets is minimized. Therefore, when inserting a permanent magnet coated with an adhesive into the magnet insertion hole, if the alignment accuracy of the permanent magnet with respect to the magnet insertion hole is insufficient, the adhesive comes into contact with the entrance of the magnet insertion hole and is peeled off. As a result, there is a risk that the fixing of the permanent magnet to the rotor core becomes insufficient.

[0004] To address the above problem, for example, in Patent Document 1, when inserting a permanent magnet coated with an adhesive into a magnet insertion hole, the surface without the adhesive is inserted along the inner wall of the magnet insertion hole, and then the rotor is rotated. Due to the centrifugal force generated by the rotation of the rotor, the surface of the permanent magnet coated with the adhesive is pressed against the inner wall of the magnet insertion hole. Thereby, when inserting the permanent magnet coated with the adhesive into the magnet insertion hole, the amount of adhesive peeled off can be suppressed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] There is a need for a method for manufacturing a rotor that is not limited to the method disclosed in Patent Document 1, but can suppress the amount of adhesive peeled off when inserting a permanent magnet coated with adhesive into a magnet insertion hole, thereby ensuring stable adhesive strength.

[0007] This disclosure was made to solve these problems and provides a method for manufacturing a rotor in which permanent magnets can be stably bonded to the rotor core. [Means for solving the problem]

[0008] A rotor manufacturing method according to the present disclosure comprises a rotor core, a plurality of magnet insertion holes that penetrate the rotor core in the axial direction and are arranged along the circumferential direction of the rotor core, permanent magnets inserted into the magnet insertion holes, and an adhesive interposed between the inner wall of the magnet insertion hole and the permanent magnet, wherein the adhesive is applied to the permanent magnet before inserting the permanent magnet into the magnet insertion hole, the permanent magnet is aligned within the magnet insertion hole while an external magnetic field is applied, and the magnetic force acting on the permanent magnet by the external magnetic field acts in the opposite direction to the attractive force that draws the permanent magnet to the rotor core within the magnet insertion hole.

[0009] The permanent magnet is aligned within the magnet insertion hole using a magnetic force in the opposite direction to its attractive force. This reduces the amount of adhesive that is stripped off when the adhesive-coated permanent magnet is inserted into the magnet insertion hole due to contact with the entrance of the hole. As a result, the permanent magnet can be stably bonded to the rotor core.

[0010] The external magnetic field may be generated by energizing a coil provided in the stator that surrounds the outer circumference of the rotor core.

[0011] The external magnetic field may be applied starting before the permanent magnet is inserted into the magnet insertion hole, and may continue to be applied during insertion.

[0012] The external magnetic field may be applied after the permanent magnet has been inserted into the magnet insertion hole.

[0013] The adhesive may be applied to at least one of the surfaces of the permanent magnet, either the surface in the direction in which the magnetic force acts or the surface in the direction in which the attractive force acts. [Effects of the Invention]

[0014] The present invention provides a method for manufacturing a rotor in which permanent magnets can be stably bonded to the rotor core. [Brief explanation of the drawing]

[0015] [Figure 1] This is a plan view of the rotor according to Embodiment 1. [Figure 2] This is a plan view of the rotor core and stator according to Embodiment 1. [Figure 3] This is an enlarged view of a permanent magnet according to Embodiment 1, in a state where an external magnetic field is applied. [Figure 4] This is a flowchart of the method for manufacturing a rotor according to Embodiment 1. [Figure 5] This is a cross-sectional view along the cutting line III-III in Figure 3. [Figure 6] This is a flowchart of the method for manufacturing a rotor according to Embodiment 2. [Figure 7] This is a cross-sectional view along the cutting line III-III in Figure 3. [Modes for carrying out the invention]

[0016] The following describes specific embodiments of this disclosure in detail with reference to the drawings. However, this disclosure is not limited to the following embodiments. Also, for clarity, the following descriptions and drawings have been simplified as appropriate.

[0017] (Embodiment 1) <Rotor Configuration> First, referring to FIG. 1, the configuration of the rotor according to Embodiment 1 will be described. FIG. 1 is a plan view of the rotor according to Embodiment 1.

[0018] As shown in FIG. 1, the rotor 1 includes a rotor core 10, a permanent magnet 20, and an adhesive 30. In the following description, the xyz three-dimensional orthogonal coordinate system will be used as appropriate. In the present disclosure, the rotation axis direction of the rotor 1 is the z-axis direction.

[0019] The rotor core 10 is a cylindrical member. The rotor core 10 is composed of, for example, a laminate of electromagnetic steel sheets. A shaft (not shown) is inserted into the hollow 11 of the rotor core 10. A plurality of magnet insertion holes 12 are formed near the outer peripheral portion of the rotor core 10.

[0020] The magnet insertion holes 12 penetrate in the axial direction (z-axis direction) of the rotor core 10 and are arranged in a plurality along the circumferential direction of the rotor core 10. The magnet insertion holes 12 are formed in a substantially rectangular shape in a plan view (xy plane view) of the rotor 1. Also, a pair of adjacent magnet insertion holes 12 are arranged in a V shape that opens outward in the radial direction, and a plurality of such pairs of magnet insertion holes 12 are arranged along the circumferential direction of the rotor core 10.

[0021] The permanent magnet 20 is formed in a rectangular shape in a plan view (xy plane view) of the rotor 1. That is, the permanent magnet 20 has a rectangular parallelepiped shape with side surfaces extending along the axial direction (z-axis direction).

[0022] The permanent magnets 20 are inserted into the respective magnet insertion holes 12 in a pre-magnetized state. The permanent magnet 20 is configured such that the magnetization direction (magnetization direction) is the short side direction in a plan view (xy plane view). That is, the permanent magnet 20 has a pair of magnetic pole surfaces 21 and 22 at both ends in the short side direction of the rectangle in a plan view (xy plane view) of the rotor 1. The pair of magnetic pole surfaces 21 and 22 are surfaces that are orthogonal or intersect the magnetic force lines L1 in each permanent magnet 20 and are surfaces where magnetic poles appear. Note that the magnetic pole surface 21 is the N pole and the magnetic pole surface 22 is the S pole.

[0023] The material for the permanent magnet 20 can be a metallic magnet material, such as a neodymium sintered magnet. Neodymium magnets can use rare earth elements such as Nd, Dy, and Tb, but are not particularly limited, and other rare earth elements such as Ce, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu may also be used.

[0024] The adhesive 30 is interposed between the inner wall of the magnet insertion hole 12 and the permanent magnet 20, fixing the permanent magnet 20 to the rotor core 10. In Figure 1, the adhesive 30 is provided on both sides of the pair of magnetic pole surfaces 21 and 22, but it is sufficient if it is provided on at least one side of the pair of magnetic pole surfaces 21 and 22. The type of adhesive 30 is not particularly limited and examples include thermoplastic resins and thermosetting resins.

[0025] <How to manufacture a rotor> Next, the method for manufacturing the rotor will be described. The rotor 1 is manufactured by inserting permanent magnets 20 coated with adhesive 30 into magnet insertion holes 12 and curing the adhesive 30. First, the method for aligning the permanent magnets 20 within the magnet insertion holes 12 will be described with reference to Figures 2 and 3. Figure 2 is a plan view of the rotor core and stator according to Embodiment 1. Figure 3 is an enlarged view of the permanent magnet according to Embodiment 1 with an external magnetic field applied.

[0026] In order to align the permanent magnet 20 within the magnet insertion hole 12, as shown in Figure 2, in this embodiment 1, a stator 2 is used to surround the outer circumference of the rotor core 10. The stator 2 generates an external magnetic field when a coil C provided on the stator 2 is energized. Note that other devices may be used as long as they can generate an external magnetic field, and are not limited to the stator 2. As shown in Figure 2, the magnetic field lines L2 due to the external magnetic field act in approximately the opposite direction to the magnetic field lines L1 due to the permanent magnet 20 near the permanent magnet 20.

[0027] As shown in Figure 3, when an external magnetic field is applied to the permanent magnet 20, an attractive force F1 and a magnetic force F2 act upon it, and these attractive force F1 and magnetic force F2 act in opposite directions on the permanent magnet 20. The attractive force F1 is the force that pulls the permanent magnet 20 towards the rotor core 10, which is a magnetic material, within the magnet insertion hole 12. The magnetic force F2 is the force that acts on the permanent magnet 20 due to the external magnetic field, and more specifically, it is the force of repulsion between the magnetic flux due to the external magnetic field and the magnetic flux due to the permanent magnet 20.

[0028] The magnitude of the magnetic force F2 is controlled by controlling the magnitude of the external magnetic field, that is, by controlling the magnitude of the current flowing through coil C. Therefore, by controlling the attractive force F1 relative to the magnetic force F2, the permanent magnet 20 is aligned within the magnet insertion hole 12. For example, the permanent magnet 20 can be centered within the magnet insertion hole 12 when the magnetic force F2 balances the attractive force F1.

[0029] The method for aligning the permanent magnet 20 within the magnet insertion hole 12 has been described above. Next, the method for manufacturing the rotor will be described in detail with reference to Figures 4 and 5. Figure 4 is a flowchart of the method for manufacturing the rotor according to Embodiment 1. Figure 5 is a cross-sectional view taken along the cutting line III-III in Figure 3. Note that Figure 5 shows the state before the permanent magnet 20 is inserted into the magnet insertion hole 12.

[0030] First, adhesive 30 is applied to the permanent magnet 20 (step S101). The adhesive 30 is applied to at least one of the surfaces of the permanent magnet 20, either the surface in the direction in which the attractive force F1 acts or the surface in the direction in which the magnetic force F2 acts. In this embodiment 1, the adhesive 30 is applied to both the surface in the direction in which the attractive force F1 acts and the surface in the direction in which the magnetic force F2 acts. Note that the permanent magnet 20 is pre-magnetized before step S101.

[0031] Next, the application of an external magnetic field is started (step S102). More specifically, an external magnetic field is generated by energizing a coil C provided in the stator 2 that surrounds the outer circumference of the rotor core. Then, the permanent magnet 20 is aligned with the magnet insertion hole 12 by adjusting the magnitude of the magnetic force F2.

[0032] Here, the attractive force F1 acts on the pole surface 21, 22 of the permanent magnet 20 that is closer to the inner wall of the magnet insertion hole 12. In Figure 5, in order to apply the attractive force F1 to the north pole surface 21, the permanent magnet 20 is positioned such that its central axis Z2 in the cross-sectional view along the cutting line III-III is on the north pole surface 21 side relative to the central axis Z1 of the magnet insertion hole 12. If you want to apply the attractive force F1 to the south pole surface 22, position the permanent magnet 20 so that its central axis Z2 in the cross-sectional view along the cutting line III-III is on the south pole surface 22 side relative to the central axis Z1 of the magnet insertion hole 12.

[0033] Furthermore, when the side of the permanent magnet 20 facing the direction in which the attractive force F1 acts is brought close to the inner wall of the magnet insertion hole 12, in the step of applying adhesive 30 to the permanent magnet 20 (step S101), the thickness of the adhesive 30a applied to the side facing the direction in which the attractive force F1 acts may be smaller than the thickness of the adhesive 30b applied to the side facing the direction in which the magnetic force F2 acts. This makes it possible to suppress the amount of adhesive 30 that comes into contact with the entrance of the magnet insertion hole 12 and is peeled off when the permanent magnet 20 is inserted into the magnet insertion hole 12.

[0034] Next, the permanent magnet 20 is inserted into the magnet insertion hole 12 (step S103). During step S103, an external magnetic field is continuously applied to the permanent magnet 20. That is, the permanent magnet 20 is inserted into the magnet insertion hole 12 while being aligned within the magnet insertion hole 12 by the magnetic force F2 from the external magnetic field.

[0035] Here, as the permanent magnet 20 is inserted into the magnet insertion hole 12, the area in which the surface of the permanent magnet 20 facing the direction in which the attractive force F1 acts and the inner wall of the magnet insertion hole 12 confront each other increases. That is, as the permanent magnet 20 is inserted into the magnet insertion hole 12, the attractive force F1 increases. Therefore, the current value flowing through coil C is controlled to increase the magnetic force F2 in accordance with the increase in the attractive force F1. By controlling the magnetic force F2 in relation to the attractive force F1 in this way, the permanent magnet 20 is aligned within the magnet insertion hole 12, and the amount of adhesive 30 that comes into contact with the entrance of the magnet insertion hole 12 and is peeled off can be suppressed. Note that the application of the external magnetic field is terminated after the permanent magnet 20 has been inserted into the magnet insertion hole 12 and the adhesive 30 has hardened.

[0036] As described above, in the rotor manufacturing method according to this embodiment 1, the permanent magnet 20 is aligned within the magnet insertion hole 12 by the magnetic force F2 of the external magnetic field, under the condition that an external magnetic field is applied. As a result, when the permanent magnet 20 coated with adhesive 30 is inserted into the magnet insertion hole 12, the amount of adhesive 30 that comes into contact with the entrance of the magnet insertion hole 12 and is peeled off is suppressed. Therefore, the permanent magnet 20 can be stably bonded to the rotor core 10.

[0037] (Embodiment 2) Next, the method for manufacturing a rotor according to Embodiment 2 will be described with reference to Figures 6 and 7. Figure 6 is a flowchart of the method for manufacturing a rotor according to Embodiment 2. Figure 7 is a cross-sectional view taken along the cutting line III-III in Figure 3. The upper part of Figure 7 shows the state before inserting the permanent magnet 20 into the magnet insertion hole 12. The lower part of Figure 7 shows the state after inserting the permanent magnet 20 into the magnet insertion hole 12 and applying an external magnetic field.

[0038] In the rotor manufacturing method according to Embodiment 1, the external magnetic field is applied starting before the permanent magnet 20 is inserted into the magnet insertion hole 12, and continues to be applied while the permanent magnet 20 is being inserted into the magnet insertion hole 12. On the other hand, in the rotor manufacturing method according to Embodiment 2, the external magnetic field is applied starting after the permanent magnet 20 is inserted into the magnet insertion hole 12. That is, the external magnetic field is not applied while the permanent magnet 20 is being inserted into the magnet insertion hole 12. The rotor manufacturing method according to Embodiment 2 will be described in detail below. Note that the configuration of the rotor 1 according to Embodiment 2 is the same as that of the rotor 1 according to Embodiment 1, so the explanation will be omitted.

[0039] First, adhesive 30 is applied to the permanent magnet 20 (step S104). The adhesive 30 is applied to the side of the permanent magnet 20 in the direction in which the magnetic force F2 acts, even if it is not present. In this embodiment 2, adhesive 30 is not applied to the side in the direction in which the attractive force F1 acts. Note that the permanent magnet 20 is pre-magnetized before step S104.

[0040] Next, the permanent magnet 20 is inserted into the magnet insertion hole 12 (step S105). Before inserting the permanent magnet 20 into the magnet insertion hole 12, the permanent magnet 20 is offset relative to the magnet insertion hole 12. In the upper diagram of Figure 7, in order to apply an attractive force F1 to the magnetic pole surface 21 of the north pole, the permanent magnet 20 is positioned such that its central axis Z2 in the cross-sectional view along the cutting line III-III is on the side of the magnetic pole surface 21 of the north pole relative to the central axis Z1 of the magnet insertion hole 12. If you want to apply an attractive force F1 to the magnetic pole surface 22 of the south pole, the permanent magnet 20 is positioned such that its central axis Z2 in the cross-sectional view along the cutting line III-III is on the side of the magnetic pole surface 22 of the south pole relative to the central axis Z1 of the magnet insertion hole 12.

[0041] After the above arrangement, insertion of the permanent magnet 20 into the magnet insertion hole 12 is started. Note that no external magnetic field is applied in this step S105. Therefore, as shown in the upper part of Figure 7, the side of the permanent magnet 20 on the side in which the attractive force F1 acts (the magnetic pole surface 21 in Figure 7) is attracted to the inner wall of the magnet insertion hole 12 by the attractive force F1 and comes into contact with the inner wall. That is, the permanent magnet 20 is inserted into the magnet insertion hole 12 while in contact with the inner wall of the magnet insertion hole 12.

[0042] After inserting the permanent magnet 20 into the magnet insertion hole 12 (step S105), the application of an external magnetic field is started (step S106). As a result, as shown in the lower part of Figure 7, the side facing the direction in which the magnetic force F2 acts (the magnetic pole surface 22 in Figure 7), that is, the side of the permanent magnet 20 to which the adhesive 30 is applied, is attracted to the inner wall of the magnet insertion hole 12. Therefore, the adhesive 30 comes into contact with the inner wall of the magnet insertion hole 12. This suppresses the amount of adhesive 30 that is stripped off the permanent magnet 20 by contacting the entrance of the magnet insertion hole 12. After the permanent magnet 20 has been inserted into the magnet insertion hole 12 and the adhesive 30 has hardened, the application of the external magnetic field is stopped.

[0043] As described above, in the rotor manufacturing method according to this second embodiment, adhesive 30 is not applied to the surface of the permanent magnet 20 on the side in which the attractive force F1 acts. The external magnetic field is applied only after the permanent magnet 20 is inserted into the magnet insertion hole 12. That is, no external magnetic field is applied while the permanent magnet 20 is being inserted into the magnet insertion hole 12. As a result, when the permanent magnet 20 coated with adhesive 30 is inserted into the magnet insertion hole 12, the amount of adhesive 30 that comes into contact with the entrance of the magnet insertion hole 12 and is peeled off is suppressed. Therefore, the permanent magnet 20 can be stably bonded to the rotor core 10.

[0044] It should be noted that the present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. [Explanation of Symbols]

[0045] 1 rotor 2 staters 10 rotor cores 11 Hollow 12 Magnet insertion holes 20 permanent magnets 21, 22 magnetic pole face 30, 30a, 30b Adhesives C coil F1 Suction power F2 magnetic force L1, L2 magnetic field lines Z1, Z2 center axis

Claims

1. Rotor core and The rotor core has multiple magnet insertion holes that penetrate it in the axial direction and are arranged along the circumferential direction of the rotor core, A permanent magnet inserted into the aforementioned magnet insertion hole, A method for manufacturing a rotor, comprising an adhesive interposed between the inner wall of the magnet insertion hole and the permanent magnet, The adhesive is applied to the permanent magnet before inserting the permanent magnet into the magnet insertion hole. The permanent magnet is aligned within the magnet insertion hole while an external magnetic field is applied. The magnetic force acting on the permanent magnet due to the external magnetic field acts in the opposite direction to the direction of the attractive force that draws the permanent magnet to the rotor core within the magnet insertion hole. A method for manufacturing a rotor.

2. The aforementioned external magnetic field is generated by energizing a coil provided in the stator that surrounds the outer circumference of the rotor core. A method for manufacturing a rotor according to claim 1.

3. The external magnetic field is applied starting before the permanent magnet is inserted into the magnet insertion hole and continues to be applied during insertion. A method for manufacturing a rotor according to claim 1 or 2.

4. The external magnetic field is applied starting after the permanent magnet is inserted into the magnet insertion hole. A method for manufacturing a rotor according to claim 1 or 2.

5. The adhesive is applied to at least one of the surfaces of the permanent magnet in the direction in which the magnetic force acts or the surface in the direction in which the attractive force acts. A method for manufacturing a rotor according to claim 1 or 2.

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