Rotor manufacturing equipment

Abstract

To provide a rotor manufacturing apparatus capable of providing sufficient magnetization on the entire permanent magnet buried in a rotor core and suppressing generation of heat at the apparatus when magnetized.SOLUTION: A rotor to be magnetized is provided in a state where a permanent magnet having a projected folded shape inside in a radial direction is buried in a rotor core. A magnetization device 30 comprises, in addition to an outer diameter side main yoke 32 of a main magnetization part 30a constituting a magnetic path for supplying a magnetization magnetic flux to the permanent magnet, auxiliary yokes 34 and 42 of auxiliary magnetization parts 30b and 30c arranged on both sides of the rotor in an axial direction. The magnetization magnetic flux can be supplied to a bent part or the like of the permanent magnet which the magnetization magnetic flux is difficult to reach by inserting insertion projections 34d and 42d of the yokes 34 and 42 and executing magnetization. The yoke 32 is composed of a steel plate laminate A11, a slit 32c and the yokes 34 and 42 are composed of powder magnetic cores A12 and A14 on a tip surface 32a1 of an opposite projection 32a, and thus eddy current generated at each magnetic path by the magnetization magnetic flux can be suppressed.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a rotor manufacturing apparatus that includes external magnetization of permanent magnets in an embedded magnet rotor. [Background technology]

[0002] Rotating electric machines using interior permanent magnet (IPM) rotors are well known. Interior permanent magnet rotors have permanent magnets embedded in a rotor core, and generate reluctance torque at radially outer portions of the permanent magnets in the rotor core. Some interior permanent magnet rotors have a rotor core with embedded, unmagnetized permanent magnets that is magnetized from the outer diameter side by a magnetizing device (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-144322 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, one way to improve the performance of an embedded magnet rotor is to make the permanent magnets approximately V- or U-shaped and make the radially outer portion of the rotor core larger than the permanent magnets, thereby increasing the reluctance torque.

[0005] However, in an attempt to increase the size of the radially outer portion of the rotor core relative to the permanent magnet, the deeper the folded portion of the permanent magnet is positioned radially inward, which means that the permanent magnet, particularly the folded portion and its vicinity, will be farther away from the magnetizing device. Therefore, there is a concern as to whether the folded portion of the permanent magnet and its vicinity, which are farther away from the magnetizing device, will be sufficiently magnetized.

[0006] Furthermore, since a large magnetic flux flows through the magnetic path of the magnetizing device during magnetization, there is a concern that the parts that make up the magnetic path of the magnetizing device may heat up due to eddy currents that may be generated around the magnetic flux.If the magnetizing device becomes too hot, it may affect the continuity of magnetization.

[0007] The present invention has been made to solve the above-mentioned problems. That is, an object of the present invention is to provide a rotor manufacturing apparatus that can sufficiently magnetize the entire permanent magnet embedded in a rotor core and that can suppress heat generation in the apparatus during magnetization. [Means for solving the problem]

[0008] A rotor manufacturing apparatus that solves the above problem is a rotor manufacturing apparatus for a rotor (20) having permanent magnets (23) that are embedded in magnet accommodating holes (24) of a rotor core (22) and have a folded shape that is convex radially inward, and the rotor manufacturing apparatus includes a magnetizing device (30, 50) that magnetizes the embedded permanent magnets from the outside of the rotor, wherein the magnetizing device has a yoke portion (32, 34, 42, 52, 62) that is arranged at least on the axial side of the rotor and forms a magnetic path for supplying magnetizing magnetic flux to the permanent magnet, and the yoke portion is configured using at least one of a powder magnetic core (A12, A14), a steel plate laminate (A11), and a slit (32c, 34e, 42e) that has a function of suppressing eddy currents that may be generated by the magnetizing magnetic flux.

[0009] According to the above configuration, in magnetizing a rotor in which a permanent magnet having a folded shape convex radially inward is embedded in a rotor core, the magnetizing device includes a yoke portion disposed at least on the axial side of the rotor, which forms a magnetic path for supplying magnetizing flux to the permanent magnet. The yoke portion disposed on the axial side of the rotor can supply magnetizing flux to bends and their vicinity, which are difficult to reach when magnetizing the rotor from the outer diameter side. In other words, sufficient magnetization is possible throughout the permanent magnet. Furthermore, the yoke portion disposed at least on the axial side of the rotor is constructed using at least one of a powder magnetic core, a steel sheet laminate, and a slit, thereby suppressing the generation of eddy currents that may be generated by the magnetizing flux. This suppresses heat generation during magnetization by the magnetizing device. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a configuration diagram of a rotating electric machine having an embedded magnet rotor to be magnetized by the magnetizing device of each embodiment. [Figure 2] FIG. 2 is a configuration diagram of a rotor to be magnetized by the magnetizing device of each embodiment. [Figure 3] 1 is a cross-sectional view of an example of a rotor magnetized by a magnetization device of a first embodiment. FIG. [Figure 4] FIG. 2 is an explanatory diagram for explaining the configuration of the magnetizing device of the first embodiment. [Figure 5] FIG. 2 is an explanatory diagram for explaining the configuration of the magnetizing device of the first embodiment. [Figure 6] FIG. 2 is an explanatory diagram for explaining the configuration of the magnetizing device of the first embodiment. [Figure 7] FIG. 2 is an explanatory diagram for explaining the configuration of the magnetizing device of the first embodiment. [Figure 8] FIG. 2 is an explanatory diagram for explaining a magnetizing method of the magnetizing device of the first embodiment. [Figure 9] FIG. 2 is an explanatory diagram for explaining a magnetizing method of the magnetizing device of the first embodiment. [Figure 10] FIG. 2 is an explanatory diagram for explaining a permanent magnet magnetized by the magnetizing device of the first embodiment. [Figure 11]FIG. 2 is an explanatory diagram for explaining a permanent magnet magnetized by the magnetizing device of the first embodiment. [Figure 12] FIG. 10 is a cross-sectional view of an example of a rotor magnetized by a magnetizing device of a second embodiment. [Figure 13] FIG. 4 is an explanatory diagram for explaining the overall configuration of a magnetizing device according to a second embodiment. [Figure 14] FIG. 4 is an explanatory diagram for explaining the overall configuration of a magnetizing device according to a second embodiment. [Figure 15] FIG. 4 is an explanatory diagram for explaining the overall configuration of a magnetizing device according to a second embodiment. [Figure 16] FIG. 10 is an explanatory diagram for explaining a permanent magnet magnetized by a magnetizing device of a second embodiment. [Figure 17] FIG. 10 is a table for explaining the configuration of a magnetizing device of a modified example. [Figure 18] FIG. 10 is a table for explaining the configuration of a magnetizing device of a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0011] (First embodiment) A first embodiment of a rotor manufacturing apparatus will be described below. 1, the rotating electric machine M of this embodiment is configured as an embedded magnet brushless motor. The rotating electric machine M includes a substantially annular stator 10 and a substantially cylindrical rotor 20 rotatably disposed in the radially inner space of the stator 10.

[0012] The stator 10 includes a substantially annular stator core 11. The stator core 11 is made of a magnetic metal material, e.g., multiple electromagnetic steel sheets stacked in the axial direction. The stator core 11 has twelve teeth 12, which extend radially inward and are equally spaced circumferentially in this embodiment. Each tooth 12 has the same shape. The radially inner ends of the teeth 12 are substantially T-shaped, and the tip surfaces 12a are arc-shaped, conforming to the outer circumferential surface of the rotor 20. Windings 13 are wound around the teeth 12 in a concentrated winding fashion. The windings 13 are connected in a three-phase configuration, functioning as U, V, and W phases, respectively, as shown in FIG. 1 . When power is supplied to the windings 13, a rotating magnetic field is generated in the stator 10 to rotate the rotor 20. In this stator 10, the outer circumferential surface of the stator core 11 is fixed to the inner circumferential surface of the housing 14.

[0013] The rotor 20 includes a rotating shaft 21, a substantially cylindrical rotor core 22 into whose center the rotating shaft 21 is fitted, and eight permanent magnets 23 in this embodiment embedded inside the rotor core 22. The rotor core 22 is made of a magnetic metal material, for example, made by laminating multiple electromagnetic steel plates in the axial direction. The rotor 20 is rotatably disposed relative to the stator 10 with the rotating shaft 21 supported by a bearing (not shown) provided in the housing 14.

[0014] The rotor core 22 has magnet accommodating holes 24 for accommodating the permanent magnets 23. In this embodiment, eight magnet accommodating holes 24 are provided at equal intervals around the circumferential direction of the rotor core 22. Each magnet accommodating hole 24 has a generally V-shaped folded shape that protrudes radially inward, and the magnet accommodating holes 24 are identical to each other. The magnet accommodating holes 24 are provided over the entire axial direction of the rotor core 22.

[0015] Here, the permanent magnet 23 of this embodiment is a bonded magnet made by molding and solidifying a magnetic material made by mixing magnetic powder with resin. That is, the permanent magnet 23 is formed by using the magnet accommodating hole 24 of the rotor core 22 as a molding die, filling the magnet accommodating hole 24 with unsolidified magnetic material by injection molding without gaps, and then solidifying it inside the magnet accommodating hole 24 after filling. Therefore, the hole shape of the magnet accommodating hole 24 becomes the outer shape of the permanent magnet 23. The magnetic powder used for the permanent magnet 23 of this embodiment is, for example, a samarium iron nitrogen (SmFeN) magnet, but other rare earth magnets, etc. may also be used.

[0016] The embedded permanent magnets 23 have a generally V-shaped folded shape that protrudes radially inward. Specifically, as shown in FIG. 2, the permanent magnets 23 have a shape in which the radially inner ends of a pair of straight portions 23a are connected by a bent portion 23b. The radially outer end 23c of the straight portion 23a is located near the outer peripheral surface 22a of the rotor core 22. The permanent magnets 23 have a constant thickness Wm along the V-shaped path including the pair of straight portions 23a and the bent portion 23b. The permanent magnets 23 are symmetrical with respect to their own circumferential center line Ls that passes through the axial center O1 of the rotor 20, and are adjacent to the magnetic pole boundary line Ld between adjacent permanent magnets 23 that passes through the axial center O1 of the rotor 20. The angle between adjacent magnetic pole boundary lines Ld, i.e., the magnetic pole opening angle θm of the rotor magnetic pole portion 26 including the permanent magnets 23, is 180° in electrical angle.

[0017] The magnetic pole pitch Lp is the distance between the extensions of the inner surfaces of the straight portions 23a of the permanent magnets 23 on the outer peripheral surface 22a of the rotor core 22, and the embedding depth Lm is the distance from the outer peripheral surface 22a of the rotor core 22 to the inner surfaces of the bent portions 23b of the permanent magnets 23 on the circumferential center line Ls of the permanent magnets 23. The permanent magnets 23 of this embodiment have a deep folded shape such that the embedding depth Lm is greater than the magnetic pole pitch Lp. That is, as shown in FIGS. 2 and 3 , the permanent magnets 23 of this embodiment have a deep folded shape in which their bent portions 23b are located radially inward and closer to the shaft insertion hole 22b in the center of the rotor core 22, into which the rotating shaft 21 is inserted. The permanent magnets 23 are provided over the entire axial direction of the rotor core 22.

[0018] The permanent magnets 23 solidified in the magnet accommodating holes 24 of the rotor core 22 are magnetized from the outside of the rotor core 22 using a magnetizing device 30 shown in FIG. 4 etc., so that the unmagnetized state functions as an original magnet. Details of the magnetizing device 30 and the magnetizing method using the magnetizing device 30 will be described later. In this embodiment, eight permanent magnets 23 are provided in the circumferential direction of the rotor core 22, and are magnetized so that the polarities are alternately different in the circumferential direction. Furthermore, each of the permanent magnets 23 is magnetized in its own thickness direction.

[0019] The portion of the rotor core 22 radially outward of the permanent magnets 23 and facing the stator 10 functions as an outer core portion 25 for generating reluctance torque. The rotor 20 includes the permanent magnets 23 and the outer core portion 25 surrounded by the substantially V-shaped spaces between the individual permanent magnets 23, and is configured as eight rotor magnetic pole portions 26 in this embodiment. The rotor magnetic pole portions 26 alternate in the circumferential direction as shown in FIG. 1 . A rotor 20 having such rotor magnetic pole portions 26 can effectively generate magnet torque and reluctance torque. The above-described shape of the permanent magnets 23 is merely an example and may be modified as appropriate. The configuration of the rotating electric machine M may also be modified as appropriate.

[0020] Next, the configuration of the magnetizing device 30 and the magnetizing method of this embodiment will be described. [Magnetization device configuration] The magnetizing device 30 of this embodiment will be described with reference to Fig. 4 to Fig. 7. Note that hatching has been omitted from cross-sectional portions as appropriate in Fig. 4 to Fig. 7. Also, Fig. 6 illustrates the rotor 20 as a cross section, and the magnetizing device 30 as an end face.

[0021] 4 to 7, the magnetizing device 30 includes a device main body 31 and a device upper part 41, and is configured so that the device upper part 41 can be moved toward and away from the device main body 31 so as to enable the installation and removal of the rotor 20 to be magnetized. Note that the arrangement and operation of the device main body 31 and the device upper part 41 are merely examples and can be changed as appropriate.

[0022] The device main body 31 integrally includes a main magnetization section 30a and a lower auxiliary magnetization section 30b. The main magnetization section 30a includes an outer diameter side main yoke 32 made of magnetic metal and a magnetization main coil 33. The outer diameter side main yoke 32 has eight magnetization opposing convex sections 32a provided corresponding to each rotor magnetic pole section 26 of the rotor 20 installed in the magnetization device 30. The tip end surface 32a1, which is the radially inner end of each magnetization opposing convex section 32a, is positioned so as to face the outer peripheral surface 22a of the rotor 20 (rotor core 22) in close proximity in the radial direction. A magnetization main coil 33 is wound around each magnetization opposing convex section 32a with its winding axis facing radially. The magnetization main coil 33 is surrounded by a coil holding section 39 covered and hardened with a thermosetting resin such as epoxy resin. The coil holding portion 39 regulates the shape of the magnetizing main coil 33 to prevent deformation or unwinding when current is applied to the magnetizing main coil 33. The coil holding portion 38 also absorbs heat from the magnetizing main coil 33 that generates heat when current is applied and protects the magnetizing main coil 33 during assembly. The radial outer periphery of the outer diameter side main yoke 32 is formed as an annular connecting portion 32b that circumferentially integrally connects the magnetizing opposing convex portions 32a that are provided at equal intervals in the circumferential direction (see FIG. 7).

[0023] The lower auxiliary magnetization portion 30b includes a lower auxiliary yoke 34 made of magnetic metal and a lower auxiliary magnetization coil 35. The lower auxiliary yoke 34 includes eight lower connecting portions 34a provided corresponding to the magnetization opposing convex portions 32a, and one lower assembly portion 34b that groups together the lower connecting portions 34a. One end of each lower connecting portion 34a is integrally connected to the lower surface portion of the annular connecting portion 32b of the outer diameter side main yoke 32. Each lower connecting portion 34a has a shape that detours downward in the axial direction while avoiding the magnetization main coil 33 and the like, and the other end of each lower connecting portion 34a is integrally connected to the lower assembly portion 34b.

[0024] The lower collection portion 34b is located below the rotor 20 installed in the magnetization device 30, and has a columnar shape along the axial direction of the rotor 20. The lower collection portion 34b has, at the center of its upper surface, a contact portion 34c against which the rotor 20 is placed and contacts, and a lower insertion protrusion 34d located inside the contact portion 34c and inserted from below into the shaft insertion hole 22b in the center of the rotor 20. A protrusion length L1 of the lower insertion protrusion 34d is configured to be longer than a protrusion length L2 of an upper insertion protrusion 42d, which will be described later.

[0025] A lower auxiliary coil for magnetization 35 is wound around the lower assembly portion 34b with its winding axis facing the axial direction. A cylindrical lower first restricting member 36 made of a non-magnetic metal is attached to the outer periphery of the lower auxiliary coil for magnetization 35, and a plate-shaped lower second restricting member 37 made of a non-magnetic metal is fixed to the lower assembly portion 34b and the like above the axial direction of the lower auxiliary coil for magnetization 35. The upper surfaces of the lower second restricting member 37 and the abutment portion 34c are, for example, flush with each other. The restricting members 36, 37 are made of, for example, stainless steel. Inside the restricting members 36, 37, the lower auxiliary coil for magnetization 35 is covered and hardened with a thermosetting resin such as epoxy resin to form a coil holding portion 38. The coil holding portion 38 cooperates with the restricting members 36, 37 to restrict the shape of the lower auxiliary magnetizing coil 35 so that it does not deform or become unwound when current is applied to the coil. The coil holding portion 38 also absorbs heat from the lower auxiliary magnetizing coil 35 that generates heat when current is applied and protects the lower auxiliary magnetizing coil 35 when it is assembled.

[0026] On the other hand, the upper device section 41, which moves toward and away from the device main body section 31, only includes an upper auxiliary magnetizing section 30c. The upper auxiliary magnetizing section 30c includes an upper auxiliary yoke 42 made of magnetic metal and an upper auxiliary magnetizing coil 43. The upper auxiliary yoke 42 is configured symmetrically with the lower auxiliary yoke 34 in the vertical direction and includes eight upper connecting sections 42a corresponding to the magnetizing opposing convex sections 32a, and one upper assembly section 42b that groups the upper connecting sections 42a together. One end of each upper connecting section 42a is configured to be able to abut against the upper surface of the annular connecting section 32b of the outer diameter side main yoke 32. Each upper connecting section 42a has a shape that detours upward in the axial direction to avoid the magnetizing main coil 33 and the like, and the other end of each upper connecting section 42a is integrally connected to the upper assembly section 42b. The upper auxiliary yoke 42 has an integral structure in which each upper connecting portion 42a is connected to an upper collection portion 42b.

[0027] The upper collection portion 42b is located above the rotor 20 installed in the magnetization device 30, and has a columnar shape along the axial direction of the rotor 20. The upper collection portion 42b has a contact portion 42c at the center of its lower surface with which the rotor 20 abuts, and an upper insertion protrusion 42d located inside the contact portion 42c and inserted from above into the shaft insertion hole 22b in the center of the rotor 20. As described above, the protrusion length L2 of the upper insertion protrusion 42d is configured to be shorter than the protrusion length L1 of the lower insertion protrusion 34d.

[0028] Additionally, an upper auxiliary coil for magnetization 43 is wound around the upper assembly portion 42b with its winding axis facing the axial direction. A cylindrical upper first restricting member 44 made of a non-magnetic metal is attached to the outer periphery of the upper auxiliary coil for magnetization 43, and a plate-shaped upper second restricting member 45 made of a non-magnetic metal is fixed to the upper assembly portion 42b and the like below the upper auxiliary coil for magnetization 43 in the axial direction. The lower surfaces of the upper second restricting member 45 and the abutting portion 42c are, for example, flush with each other. Each restricting member 44, 45 is made of, for example, stainless steel. Additionally, inside each restricting member 44, 45, the upper auxiliary coil for magnetization 43 is covered and hardened with a thermosetting resin such as epoxy resin to form a coil holding portion 46. The coil holding portion 46 cooperates with the restricting members 44, 45 to restrict the shape of the upper auxiliary magnetizing coil 43 so that it does not deform or become unwound when current is applied to the upper auxiliary magnetizing coil 43. The coil holding portion 46 also absorbs heat from the upper auxiliary magnetizing coil 43 that is generated when current is applied and protects the upper auxiliary magnetizing coil 43 when it is assembled.

[0029] The magnetizing device 30 of this embodiment magnetizes the main magnetized portion 30a by causing a magnetizing magnetic flux to flow between the circumferentially adjacent opposing magnetizing convex portions 32a through the inside of the rotor 20. In addition, the main magnetized portion 30a and the auxiliary magnetized portions 30b, 30c work together to cause a magnetizing magnetic flux to flow by a coercive force also to the inner diameter side of the rotor 20, which is difficult to reach with the main magnetized portion 30a alone. In other words, the magnetizing device 30 of this embodiment is configured to be able to effectively magnetize the permanent magnet 23, particularly the bent portion 23b located radially inward and farther from the main magnetized portion 30a, and the vicinity thereof.

[0030] [Magnetic method using a magnetizing device] Using the magnetization device 30 configured as described above, first, the rotor 20 having the unmagnetized permanent magnets 23 is placed on the magnetization device 30. The rotor 20 to be magnetized is in a state before the rotary shaft 21 is inserted, and the shaft insertion hole 22b is in an open state.

[0031] 6 and 7, with the upper part 41 of the device spaced upward from the main body 31, the rotor 20 having the unmagnetized permanent magnets 23 is placed on the upper surface of the lower assembly part 34b of the main body 31. At this time, the lower insertion protrusion 34d is inserted into the shaft insertion hole 22b of the rotor 20. Because the lower insertion protrusion 34d is configured to be long, the rotor 20 is stably supported by the insertion of the lower insertion protrusion 34d. Furthermore, because the upper insertion protrusion 42d of the upper part 41 is short and there is little risk of contact with surrounding components, the upper part 41 can be easily moved.

[0032] 4 and 5, when the rotor 20 is installed in the device main body 31, the device upper part 41 is lowered in the axial direction, and the upper insertion protrusion 42d is inserted into the shaft insertion hole 22b of the rotor 20. The device upper part 41 is lowered until one end of the upper connecting part 42a of the upper auxiliary yoke 42 abuts on the upper surface of the outer diameter side main yoke 32. In other words, the upper auxiliary yoke 42 and the outer diameter side main yoke 32 are magnetically connected, allowing the magnetizing magnetic flux to flow smoothly between them.

[0033] Next, in this embodiment, the unmagnetized permanent magnets 23 of the rotor 20 are magnetized in two steps, and in this embodiment, for example, the S pole is magnetized first, and then the N pole is magnetized. This magnetization order is one example, and the magnetization order may be reversed.

[0034] In the case of S-pole magnetization, S-pole magnetization is performed on every other permanent magnet 23 to be magnetized as an S-pole among the eight unmagnetized permanent magnets 23 arranged circumferentially on the rotor 20. That is, current for S-pole magnetization is applied from the current application device CU shown in Fig. 5 to the magnetization main coil 33 and the auxiliary coils 35, 43 attached to every other circumferentially magnetizing opposing convex portions 32a for magnetization 32a. Then, inside the rotor 20, as shown in Fig. 8, magnetization magnetic flux flows from each of the magnetization opposing convex portions 32a of the outer diameter side main yoke 32 toward each of the insertion protrusions 34d, 42d of each of the auxiliary yokes 34, 42.

[0035] At this time, the magnetizing opposing convex portions 32a and the insertion protrusions 34d, 42d, which are magnetically connected to each other, are opposed to each other on the radially outer and inner sides of the rotor 20, increasing the magnetizing magnetic flux that advances throughout the entire interior of the rotor 20, from the radially outer side to the radially inner side of the rotor 20. Furthermore, by providing auxiliary coils 35, 43 and energizing them to cooperate with the magnetizing main coil 33, a stronger coercive force can be applied to the flow of the magnetizing magnetic flux, making it possible to more effectively maintain a suitable flow of magnetic flux.

[0036] In the case of N-pole magnetization, N-pole magnetization is performed on every other remaining permanent magnet 23 of the rotor 20 that is to be magnetized as an N-pole. That is, the current supply unit CU supplies current for N-pole magnetization in the opposite direction to that for S-pole magnetization to the magnetization main coil 33 and the auxiliary coils 35, 43 attached to every other circumferentially opposing magnetization convex portion 32a for magnetization that is to be magnetized as an N-pole. Then, inside the rotor 20, as shown in Fig. 9, a magnetization magnetic flux flows from the insertion protrusions 34d, 42d of the auxiliary yokes 34, 42 toward each magnetization opposing convex portion 32a of the outer diameter side main yoke 32, in the opposite direction to that during S-pole magnetization.

[0037] Similarly, in this case, the magnetizing opposing convex portions 32a and the insertion protrusions 34d, 42d, which are magnetically connected to each other, are opposed to each other in the radial direction of the rotor 20, and this increases the magnetizing magnetic flux that advances throughout the entire interior of the rotor 20, from the radial inside to the radial outside of the rotor 20. Similarly, by providing auxiliary coils 35, 43 and energizing them together with the magnetizing main coil 33, a stronger coercive force can be applied to the flow of the magnetizing magnetic flux of the N pole, making it possible to more effectively maintain a suitable flow of magnetic flux.

[0038] Therefore, even if bent portion 23b, which is the folded portion, is located radially inward, as in permanent magnet 23 of this embodiment, which has a substantially V-shaped folded shape, it is possible to effectively magnetize bent portion 23b, which is farther from main magnetized portion 30a, and its vicinity. This is particularly useful when the folded shape is deep, such that embedded depth Lm is greater than magnetic pole pitch Lp, as in permanent magnet 23 of this embodiment.

[0039] If a conventional magnetization method were to be used in which magnetization was performed using only the main magnetized portion 30a on the outer diameter side without using auxiliary magnetized portions 30b and 30c, the magnetic force of the magnetizing flux passing through the radially inner side of rotor 20 would be weak, and the magnetic force would be weak at and around bent portion 23b of permanent magnet 23. In particular, when a deep folded shape like permanent magnet 23 of this embodiment is adopted, the magnetic force at and around bent portion 23b tends to be even weaker. Furthermore, as shown in Figure 10, the magnetic force tends to be weakest at vertical center portion 23d of bent portion 23b of permanent magnet 23.

[0040] However, by using the magnetization method of this embodiment, as shown in Fig. 10, it is possible to magnetize the permanent magnet 23 with a magnetic field strength that exceeds the desired lower limit, even in the vertical central portion 23d of the bent portion 23b, which is a point of concern. The portions above and below the vertical central portion 23d of the bent portion 23b and the straight portion 23a can be magnetized with a sufficient magnetic field strength. Furthermore, as shown in Fig. 11, if the inflection point at which the change in magnetic field strength of the permanent magnet 23 becomes gradual is set as the desired lower limit, the portion magnetized with a magnetic field strength that exceeds the desired lower limit will be more than 90% to approximately 95%, making it possible to magnetize the entire permanent magnet 23 with a sufficient magnetic force.

[0041] [Measures to prevent heat generation from magnetizing devices] In the magnetizing device 30 of this embodiment, measures are taken to prevent heat generation during magnetization in each of the main magnetizing section 30a and lower auxiliary magnetizing section 30b in the device main body section 31, and the upper auxiliary magnetizing section 30c in the device upper section 41.

[0042] As shown in FIG. 7 , regarding the main magnetization portion 30a and the lower auxiliary magnetization portion 30b of the device body 31, first, the outer diameter side main yoke 32 of the main magnetization portion 30a is composed of a steel plate laminate A11 in which multiple electromagnetic steel sheets 32x are stacked in the vertical direction. The generation of eddy currents when magnetizing magnetic flux flows is suppressed throughout the entire outer diameter side main yoke 32 made of the steel plate laminate A11. The outer diameter side main yoke 32 can be manufactured relatively easily by stacking the same electromagnetic steel sheets 32x. Furthermore, slits 32c extending in a direction intersecting the eddy currents generated by the magnetizing magnetic flux are formed on the tip end surface 32a1 of each magnetization opposing convex portion 32a of the outer diameter side main yoke 32. The slits 32c are, for example, in a lattice pattern that includes multiple first slit portions extending in the vertical direction and second slit portions extending in the circumferential direction perpendicular to the first slit portions. Eddy currents are further suppressed at the tip end surface 32a1 of each of the opposing magnetizing convex portions 32a.

[0043] Next, the lower auxiliary yoke 34 of the lower auxiliary magnetized portion 30b is substantially entirely made of the powder core A12, except for the lower insertion protrusion 34d and the abutment portion 34c. The powder core A12 is formed by compressing and molding magnetic metal powder coated with insulating resin, and is configured to have high electrical resistance. The generation of eddy currents when magnetizing magnetic flux flows is suppressed throughout substantially the entire lower auxiliary yoke 34 made of the powder core A12. Regarding the shape of the lower auxiliary yoke 34, except for the lower insertion protrusion 34d and the abutment portion 34c, molding the powder core A12 is relatively easier than laminating steel plates. One end of the lower connecting portion 34a of the lower auxiliary yoke 34 and the underside of the annular connecting portion 32b of the outer diameter side main yoke 32 are fixed together, for example, with an adhesive, and are magnetically connected to each other.

[0044] The portion including the lower insertion protrusion 34d and the abutment portion 34c is made of steel material A13, a magnetic metal. The outer peripheral surface 34d1 of the lower insertion protrusion 34d is formed with slits 34e in a direction intersecting with eddy currents generated by the magnetizing magnetic flux. The slits 34e are, for example, in a lattice pattern consisting of multiple vertical slits and circumferential slits perpendicular to the vertical slits (not shown, as they are similar to the slits 32c described above). Eddy currents are suppressed on the outer peripheral surface 34d1 of the lower insertion protrusion 34d. Furthermore, by using steel material A13, the lower insertion protrusion 34d is configured with high rigidity. Furthermore, the abutment portion 34c, which may come into contact with the rotor 20, is also configured with high rigidity. In other words, the lower auxiliary yoke 34, other than the lower insertion protrusion 34d and the abutment portion 34c, which require rigidity, is made of powder magnetic core A12, thereby effectively suppressing eddy currents.

[0045] Next, with regard to the upper auxiliary magnetized portion 30c of the device upper portion 41, the upper auxiliary yoke 42 is substantially entirely made of powder magnetic core A14, except for the upper insertion protrusion 42d, the abutment portion 42c, and one end of the upper connecting portion 42a. The generation of eddy currents when magnetizing magnetic flux flows is suppressed throughout substantially the entire upper auxiliary yoke 42 made of powder magnetic core A14. As with the lower auxiliary yoke 34, the upper auxiliary yoke 42 can also be manufactured more easily by molding powder magnetic core A14 than by laminating steel sheets.

[0046] The portion including the upper insertion protrusion 42d and the abutment portion 42c is made of steel material A15, a magnetic metal. Slits 42e are formed in the outer peripheral surface 42d1 of the upper insertion protrusion 42d in a direction that intersects with eddy currents generated by the magnetizing magnetic flux. The slits 42e have the same configuration as the slits 34e of the lower auxiliary yoke 34, and similarly suppress eddy currents on the outer peripheral surface 42d1. Furthermore, by being made from steel material A15, the upper insertion protrusion 42d is configured to have high rigidity. Similarly, the abutment portion 42c, which may come into contact with the rotor 20, is also configured to have high rigidity.

[0047] Furthermore, when the device upper section 41 moves toward or away from the device main body 31, one end of the upper connecting portion 42a of the upper auxiliary yoke 42 abuts against the upper surface of the annular connecting portion 32b of the outer diameter side main yoke 32, magnetically connecting them. A steel plate A16 is attached to each end of the multiple upper connecting portions 42a. The steel plate A16 is made of, for example, the same steel plate as the electromagnetic steel plate 32x constituting the outer diameter side main yoke 32. The one end of the upper connecting portion 42a that abuts against the outer diameter side main yoke 32 is configured to have high rigidity. In other words, the upper auxiliary yoke 42, except for the upper insertion protrusion 42d and abutment portion 42c, which require rigidity, and the one end of the upper connecting portion 42a, is made of the powder magnetic core A14, thereby effectively suppressing eddy currents in the upper auxiliary yoke 42 as well.

[0048] In this way, eddy current suppression suited to each portion is achieved in the main magnetizing portion 30a, the lower auxiliary magnetizing portion 30b, and the upper auxiliary magnetizing portion 30c of the magnetizing device 30 of this embodiment. In other words, when magnetizing magnetic flux flows through the main yoke 32 and the auxiliary yokes 34, 42 that constitute each magnetic path of the magnetizing device 30, heat generation in each magnetic path is effectively suppressed.

[0049] [Effects of this embodiment] The effects of this embodiment will be described. (1-1) In the magnetization of the rotor 20 to be magnetized in this embodiment, a concern exists in that, in conventional magnetization from the outer diameter side of the rotor 20, the magnetizing magnetic flux has difficulty reaching the bent portions 23b of the permanent magnets 23 located radially inward and their vicinity. The magnetization device 30 includes an outer diameter-side main yoke 32 of the main magnetization portion 30a as a yoke portion that constitutes a magnetic path for supplying the magnetizing magnetic flux to the permanent magnets 23 inside the rotor 20, as well as auxiliary yokes 34, 42 of the auxiliary magnetization portions 30b, 30c that are disposed on both axial sides of the rotor 20. The outer diameter-side main yoke 32 corresponds to the first yoke, and the auxiliary yokes 34, 42 correspond to the second yoke. By inserting insertion protrusions 34d, 42d provided on parts of the auxiliary yokes 34, 42 into the shaft insertion hole 22b of the rotor 20 to perform magnetization, it is possible to supply sufficient magnetizing magnetic flux to the bent portions 23b of the permanent magnets 23, which are considered difficult to reach. In other words, the entire permanent magnet 23 can be sufficiently magnetized.

[0050] (1-2) The outer diameter side main yoke 32 of the main magnetizing portion 30a is made of the steel plate laminate A11, and a slit 32c is formed in the tip end surface 32a1 of the magnetizing opposing convex portion 32a. Furthermore, the auxiliary yokes 34, 42 of the auxiliary magnetizing portions 30b, 30c are made of powder magnetic cores A12, A14. That is, in each magnetic path of the magnetizing device 30, the generation of eddy currents that may be generated by the magnetizing magnetic flux is suppressed. Therefore, heat generation during magnetization of the magnetizing device 30 can be suppressed, which contributes to maintaining magnetization for a long period of time.

[0051] (1-3) The device upper part 41 moves relative to the device main body part 31, and one end of the upper auxiliary yoke 42 abuts against the upper surface of the annular connecting part 32b of the outer diameter side main yoke 32. A steel plate A16 is attached to the abutting portion of the upper auxiliary yoke 42 to increase its rigidity. In other words, the main body side of the upper auxiliary yoke 42 is made of the powder core A14, which has an eddy current suppression function, to suppress heat generation during magnetization, while the use of the powder core A14 can protect against wear, chipping, and other concerns that may arise during abutment.

[0052] (1-4) The insertion protrusions 34d, 42d of the auxiliary yokes 34, 42 are made of steel materials A13, A15 to enhance their structure. The insertion protrusions 34d, 42d have slits 34e, 42e formed in their outer peripheral surfaces 34d1, 42d1, which are opposed to the inner peripheral surface of the shaft insertion hole 22b of the rotor 20. While protecting the elongated rod-shaped insertion protrusions 34d, 42d from breakage and wear with the inner peripheral surface of the shaft insertion hole 22b of the rotor 20, the slits 34e, 42e can suppress eddy currents and reduce heat generation during magnetization.

[0053] [Example of change] This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0054] As shown by the dashed lines and parenthesized symbols in Fig. 6, the insertion protrusions 34d, 42d of the auxiliary yokes 34, 42 may be provided with tapered portions 34x, 42x at their distal ends to form the insertion protrusions 34d, 42d in a tapered shape. This facilitates insertion of the insertion protrusions 34d, 42d into the shaft insertion hole 22b of the rotor 20 to be magnetized. Furthermore, even if the shaft insertion hole 22b of the rotor 20 is provided with a tapered portion 22x that widens the opening, it also facilitates insertion of the insertion protrusions 34d, 42d into the shaft insertion hole 22b.

[0055] Although the auxiliary yokes 34, 42 are provided with insertion protrusions 34d, 42d having different protrusion lengths, the insertion protrusions 34d, 42d may have the same protrusion length. Also, the protrusion length L2 of the upper insertion protrusion 42d may be zero, i.e., only the lower insertion protrusion 34d may be provided and inserted from one axial end to the other of the rotor 20. Conversely, only the upper insertion protrusion 42d may be provided.

[0056] The magnetizing main coil 33 is covered with the coil holding portion 39, but the coil holding portion 39 may be omitted. Also, the magnetizing auxiliary coils 35, 43 are covered with the coil holding portions 38, 46, respectively, and the restricting members 36, 37, 44, 45 are provided outside them, but any one of them may be omitted, or all of them may be omitted.

[0057] The upper auxiliary yoke 42 and the lower auxiliary yoke 34, and the upper auxiliary magnetizing coil 43 and the lower auxiliary magnetizing coil 35 are arranged symmetrically on one axial side and the other axial side of the rotor 20 to be magnetized, but they may be provided on only one axial side. In this case, as described above, it is preferable to insert the insertion protrusions 34d, 42d from one axial end to the other axial end of the rotor 20.

[0058] While the magnetizing main coil 33 is installed on the opposing protrusion 32a of the outer diameter main yoke 32 and the magnetizing auxiliary coils 35, 43 are installed on the respective collection portions 34b, 42b of the magnetizing auxiliary yokes 34, 42, the manner in which the magnetizing coils are installed is not limited to this. For example, for each auxiliary coil 35, 43, an auxiliary coil may be wound around each of the connecting portions 34a, 42a of the auxiliary yokes 34, 42. In this case, the collection portions 34b, 42b and the insertion protrusions 34d, 42d may be shared as in the above embodiment, or the magnetic paths may be separated from the connection portions 34a, 42a to the insertion protrusions 34d, 42d. The installation position of the main coil 33 may also be changed as appropriate to a position other than the opposing protrusion 32a. Furthermore, a common magnetizing coil may be used for the main coil 33 and the auxiliary coils 35, 43, rather than being divided between them.

[0059] 4 and other figures show that one rotor 20 is to be magnetized, but it is also possible to stack multiple rotors 20 in the axial direction and magnetize multiple rotors 20 simultaneously. By magnetizing multiple rotors 20 simultaneously in this way, productivity of the rotors 20 can be improved.

[0060] Although magnetization was performed on the rotor 20 whose size matches the rotor installation space of the magnetization device 30, if the size of the rotor 20 to be magnetized is small in the axial or radial direction, magnetization may be performed using a spacer that fills the gap in the rotor installation space. The spacer is preferably made of a magnetic metal material that has little effect on the flow of magnetization magnetic flux.

[0061] The magnetizing device 30 is configured such that the upper device part 41 is disposed above the device main body part 31, but the arrangement of the magnetizing device 30 is not limited to this. For example, the device main body part 31 and the upper device part 41 may be arranged side by side in an inclined direction or horizontal direction other than the up-down direction (vertical direction). Also, instead of moving the upper device part 41, the upper device part 41 and the device main body part 31 may be moved relatively.

[0062] As a measure to prevent heat generation, i.e., a measure to suppress eddy currents, in the magnetization device 30 of the above embodiment, as shown in FIG. 17 , the outer diameter side main yoke 32 is made of a steel plate laminate A11 and the tip end surface 32a1 of the magnetization opposing convex portion 32a is provided with a slit 32c. This may be modified as appropriate. For example, the outer diameter side main yoke 32 may be made of a powder magnetic core. Alternatively, the outer diameter side main yoke 32 may be made of a steel material and provided with a slit on the end surface through which the magnetization magnetic flux passes. Furthermore, in the above embodiment, the auxiliary yokes 34, 42 are made of powder magnetic cores A12, A14. However, the auxiliary yokes 34, 42 may be made of a steel material and provided with a slit on the end surface through which the magnetization magnetic flux passes. Alternatively, the auxiliary yokes 34, 42 may be made of a steel plate laminate. Furthermore, when a powder magnetic core is used, the outer surface may be protected by covering it with a magnetic metal cover.

[0063] (Second embodiment) A second embodiment of the rotor manufacturing apparatus will now be described. The rotor 20 to be magnetized in this embodiment shown in Fig. 12 has a short axial length La, but other parts have the same configuration as the first embodiment shown in Fig. 2. The magnetizing device 50 of this embodiment shown in Figs. 13 to 15 has a configuration that is particularly useful for magnetizing the rotor 20 with a short axial length La as shown in Fig. 12. Note that the magnetizing device 30 of the first embodiment shown in Fig. 4 etc. does not particularly care about the axial length La of the rotor 20 to be magnetized.

[0064] Next, the configuration of the magnetizing device 50 and the magnetizing method of the present embodiment will be described. [Magnetization device configuration] The magnetizing device 50 of this embodiment will be described with reference to Figures 13 to 15. In Figures 13 to 15, hatching has been omitted from cross-sectional portions as appropriate.

[0065] 13 to 15, the magnetizing device 50 includes an upper device part 51 and a lower device part 61, and is configured so that the upper device part 51 and the lower device part 61 can be moved toward and away from each other so as to enable the installation and removal of the rotor 20 to be magnetized. In this case, either or both of the upper device part 51 and the lower device part 61 can move toward and away from each other.

[0066] The upper device section 51 includes an upper magnetizing yoke 52 made of magnetic metal and a magnetizing coil 53 attached integrally to the upper magnetizing yoke 52. The upper magnetizing yoke 52 includes a base section 52a in the shape of an annular plate with a diameter slightly larger than that of the rotor 20 to be magnetized, and eight opposing protrusions 52b arranged at equal intervals in the circumferential direction on the underside of the base section 52a. Each opposing protrusion 52b abuts or closely faces the upper side surface of the rotor 20 to be magnetized, and is provided corresponding to each rotor magnetic pole section 26. A magnetizing coil 53 is attached to each opposing protrusion 52b in a wound manner around the outer circumferential surface 52c.

[0067] Each opposing protrusion 52b has a shape similar to that of the outer core portion 25 (see FIG. 2) surrounded by the permanent magnets 23 forming a V-shaped folded portion of each rotor magnetic pole portion 26. Specifically, each opposing protrusion 52b has a substantially triangular shape with one vertex facing toward the center of the rotor 20. The outer peripheral surface 52c of each opposing protrusion 52b is configured with a peripheral surface shape that substantially matches the magnet surface on the inner side of the V-shape of the permanent magnet 23 and the outer peripheral surface 22a of the rotor core 22. As a result, the main magnetizing magnetic flux entering and exiting each opposing protrusion 52b passes from the outer core portion 25 to the magnet surface of the permanent magnet 23 without passing directly through the axial end face of the permanent magnet 23, magnetizing the permanent magnet 23 in the thickness Wm direction (see FIG. 2).

[0068] The magnetizing coils 53 are provided in eight pieces, the same number as the opposing convex portions 52b. The magnetizing coils 53 are wound in alternate opposite directions in the circumferential direction. When current is applied to the magnetizing coils 53 by the current application device CU, the magnetizing coils 53 are excited so that the opposing convex portions 52b around which the magnetizing coils 53 are wound alternately have opposite polarities in the circumferential direction. The permanent magnets 23 magnetized by the magnetizing coils 53 and the opposing convex portions 52b alternate in the circumferential direction of the rotor 20.

[0069] The upper device part 51 is configured as described above, and the lower device part 61 has the same configuration as the upper device part 51. That is, as shown in FIGS. 13 to 15, the lower device part 61 is provided with a lower magnetizing yoke 62 having eight opposing protrusions 62b on the upper surface of a base part 62a, and eight magnetizing coils 63, corresponding to the upper magnetizing yoke 52 and magnetizing coil 53 of the upper device part 51. Each opposing protrusion 62b has a magnetizing coil 63 wound around its outer circumferential surface 62c. The magnetizing coils 63 are wound in opposite directions alternately in the circumferential direction. Each magnetizing coil 63 is energized by an energization unit CU.

[0070] When magnetizing the rotor 20, the upper device portion 51 and the lower device portion 61 are disposed opposite to each other in the axial direction of the rotor 20 to be magnetized, and the opposing convex portions 52b, 62b of the upper device portion 51 and the lower device portion 61 are positioned opposite to each other in the axial direction. When current is applied by the current application device CU, the opposing convex portions 52b, 62b and the magnetizing coils 53, 63 that are opposite to each other in the axial direction on the upper device portion 51 and the lower device portion 61 are excited with the same polarity.

[0071] [Magnetic method using a magnetizing device] Using the magnetizing device 50 configured as described above, first, when the upper and lower parts 51 and 61 are spaced apart from each other and in an open state, the rotor 20 having the unmagnetized permanent magnets 23 is placed between the upper and lower parts 51 and 61. After the rotor 20 to be magnetized is placed, the upper and lower parts 51 and 61 are brought relatively close to each other, and the tip surfaces 52b1 and 62b1 of the opposing convex parts 52b and 62b, which will have the same polarity when magnetized, come into contact with or closely face one axial side and the other axial side of the rotor 20, i.e., the upper surface and the lower surface.

[0072] Next, the current application device CU applies current to the magnetizing coils 53, 63 of the upper device portion 51 and the lower device portion 61. The opposing convex portions 52b, 62b of the upper device portion 51 and the lower device portion 61 are alternately excited to opposite polarities in the circumferential direction by applying current to the magnetizing coils 53, 63. Furthermore, the opposing convex portions 52b, 62b of the upper device portion 51 and the lower device portion 61 that face each other are excited to the same polarity by applying current to the magnetizing coils 53, 63.

[0073] As shown in FIG. 13 , the opposing convex portions 52 b, 62 b of the upper and lower device portions 51, 61 are magnetized to the same polarity, for example, S poles. Then, within the outer core portion 25, the magnetization magnetic flux along the axially orthogonal direction, including the thickness Wm direction of the permanent magnet 23 (see FIG. 2 ), is converted into a magnetic flux flow toward each of the opposing convex portions 52 b, 62 b on both axial sides. As a result, the permanent magnet 23 is magnetized so that the magnet surface side inside the V-shape becomes the N pole. Furthermore, when the opposing convex portions 52 b, 62 b are magnetized to the N pole, the magnetization magnetic flux along the axial direction from each of the opposing convex portions 52 b, 62 b inside the outer core portion 25 is converted into a magnetic flux flow along the axially orthogonal direction, including the thickness Wm direction of the permanent magnet 23 (not shown). As a result, the permanent magnet 23 is magnetized so that the magnet surface side inside the V-shape becomes the S pole.

[0074] Furthermore, each of the opposing protrusions 52b, 62b has a shape corresponding to the outer core portion 25 surrounded by each of the permanent magnets 23 forming a V-shaped folded shape. Therefore, the magnetizing magnetic flux entering and exiting from each of the opposing protrusions 52b, 62b does not pass directly through the axial end face of the permanent magnet 23, but the direction of the magnetic flux is suitably changed from the axial direction to a direction perpendicular to the axis within the outer core portion 25, and passes through the magnet surface on the inside of the V shape of the permanent magnet 23. In other words, the permanent magnet 23 has a magnetization state that makes it easy to magnetize in the thickness Wm direction (see FIG. 2).

[0075] Even with the permanent magnet 23 of this embodiment, which has a generally V-shaped folded shape, it is possible to supply a suitable magnetizing magnetic flux from the magnetizer 50 arranged in the axial direction of the rotor 20 to the entire permanent magnet 23, from the radially outer end 23c to the radially inner bent portion 23b. In other words, more effective magnetization can be achieved over the entire permanent magnet 23. This is particularly true for permanent magnet 23 of this embodiment, which has a deeper folded shape in which the embedding depth Lm is greater than the magnetic pole pitch Lp.

[0076] If the conventional method of magnetizing the rotor 20 from the radially outer side is used, the magnetic force tends to be weaker at and near the bent portion 23b of the permanent magnet 23 of this embodiment, which employs a particularly deep folded shape. Furthermore, as shown in Figure 16, the magnetic force tends to be weakest at the vertical center portion 23d of the bent portion 23b of the permanent magnet 23.

[0077] However, in the permanent magnet 23 magnetized using the magnetization method of this embodiment, as shown in Figure 16, it is possible to magnetize the bent portion 23b and its vicinity with a sufficient magnetic field strength that exceeds the desired lower limit. It is also possible to magnetize the vertical central portion 23d of the bent portion 23b, which is difficult to magnetize in the permanent magnet 23, with a magnetic field strength that exceeds the desired lower limit. Thus, in the permanent magnet 23 of this embodiment, the portion that is magnetized with a magnetic field strength that exceeds the desired lower limit is more than 90% to approximately 95%, and the entire permanent magnet 23 can be magnetized with a sufficient magnetic force.

[0078] [Measures to prevent heat generation from magnetizing devices] In the magnetizing device 50 of this embodiment, measures are taken to prevent heat generation during magnetization in each of the upper device section 51 and the lower device section 61.

[0079] As shown in FIG. 15 , the upper magnetizing yoke 52 of the upper device section 51 and the lower magnetizing yoke 62 of the lower device section 61 are made of powder cores A21 and A22, respectively. The upper magnetizing yoke 52 and the lower magnetizing yoke 62 made of powder cores A21 and A22 as a whole suppress the generation of eddy currents when magnetizing magnetic flux flows, similar to the auxiliary yokes 34 and 42 made of powder cores A12 and A14 in the first embodiment. In other words, when magnetizing magnetic flux flows through the magnetizing yokes 52 and 62 that constitute the magnetic paths of the magnetizing device 50, heat generation in each magnetic path is effectively suppressed. Regarding the upper magnetizing yoke 52 and the lower magnetizing yoke 62, molding the powder cores A21 and A22 is considered to be easier to manufacture than laminating steel sheets, and therefore, in this embodiment, molding is used to manufacture them.

[0080] [Effects of this embodiment] The effects of this embodiment will be described. (2-1) The magnetizing device 50 includes an upper magnetizing yoke 52 on the upper device portion 51 and a lower magnetizing yoke 62 on the lower device portion 61, which are disposed on both axial sides of the rotor 20, as yoke portions that form a magnetic path for supplying magnetizing flux to the permanent magnets 23 inside the rotor 20. The upper magnetizing yoke 52 corresponds to the first yoke, and the lower magnetizing yoke 62 corresponds to the second yoke. By bringing the opposing convex portions 52b, 62b of the magnetizing yokes 52, 62 into contact with or close to the outer core portion 25 of the rotor 20 to allow magnetizing flux of the same polarity to flow from both axial sides to perform magnetization, it is possible to supply sufficient magnetizing flux to the bent portions 23b of the permanent magnets 23, which are considered difficult to reach with the magnetizing flux. In other words, sufficient magnetization can be performed over the entire permanent magnet 23.

[0081] (2-2) The magnetizing yokes 52, 62 of the upper device part 51 and the lower device part 61 are made up of powder magnetic cores A21, A22. That is, the generation of eddy currents that may be generated by the magnetizing magnetic flux is suppressed in each magnetic path of the magnetizing device 50. Therefore, it is possible to suppress heat generation during magnetization of the magnetizing device 50, which contributes to continuing magnetization for a long period of time.

[0082] [Example of change] This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0083] Although the opposing convex portions 52b, 62b of the magnetizing device 50 are configured to have a shape that matches the shape of each outer core portion 25 when viewed in the axial direction of the rotor 20, the shape of the opposing convex portions 52b, 62b may be a shape that partially matches the shape of the outer core portion 25 or a shape that is different from the shape of the outer core portion 25.

[0084] Although not shown, insertion protrusions similar to those in the first embodiment may be provided at the center of each of the upper and lower magnetizing yokes 52 and 62, and magnetization may be performed by inserting each insertion protrusion into the shaft insertion hole 22b at the center of the rotor 20 to be magnetized. By providing each insertion protrusion, part of the magnetizing magnetic flux based on the excitation of the magnetizing coils 53, 63 flows through each insertion protrusion, thereby increasing the magnetizing magnetic flux passing through the inner diameter side of the rotor 20. This makes it possible to more effectively magnetize the bent portion 23b of the permanent magnet 23 located on the inner diameter side of the rotor 20 and its vicinity.

[0085] When magnetizing a rotor 20 that is long in the axial direction using the magnetizing device 50, the magnetization may be performed in blocks of the axial length La of the rotor 20, which allows sufficient magnetization of the permanent magnets 23, and multiple magnetized blocks may be stacked to form a rotor 20 that is long in the axial direction.

[0086] Although the magnetizing device 50 is configured with the upper device part 51 arranged on the upper side and the lower device part 61 arranged on the lower side, the arrangement of the magnetizing device 50 is not limited to this. The upper device part 51 and the lower device part 61 may be arranged side by side in a horizontal direction or an inclined direction other than the up-down direction.

[0087] As a measure to prevent heat generation, i.e., a measure to suppress eddy currents, in the magnetization device 50 of the above embodiment, the magnetizing yokes 52, 62 are constructed from powder magnetic cores A12, A14 as shown in FIG. 18 . This may be modified as appropriate. For example, the magnetizing yokes 52, 62 may be made from a steel material, and slits may be provided on the end faces through which the magnetizing magnetic flux passes, i.e., the tip surfaces 52b1, 62b1 of the opposing convex portions 52b, 62b. Furthermore, the magnetizing yokes 52, 62 may be constructed from a laminated steel sheet. Furthermore, when powder magnetic cores are used, the outer surfaces may be protected by covering them with a magnetic metal cover. [Explanation of symbols]

[0088] 20 rotor, 22 rotor core, 22b shaft insertion hole, 23 permanent magnet, 25 outer core portion (rotor core portion), 30, 50 magnetization device, 32 outer diameter side main yoke (yoke portion, first yoke), 34 lower auxiliary yoke (yoke portion, second yoke), 42 upper auxiliary yoke (yoke portion, second yoke), 32c, 34e, 42e slit, 52 upper magnetizing yoke (yoke portion, first yoke), 62 lower magnetizing yoke (yoke portion, second yoke), A11 steel plate laminate, A12 powder magnetic core, A14 powder magnetic core

Claims

1. A rotor manufacturing apparatus for a rotor (20) having permanent magnets (23) embedded in a rotor core (22) and having a folded shape that is convex on the inside in the radial direction, the rotor manufacturing apparatus including a magnetizing device (30, 50) that magnetizes the embedded permanent magnets from the outside of the rotor, the magnetizing device includes at least a yoke portion (32, 34, 42, 52, 62) disposed on an axial side of the rotor and constituting a magnetic path for supplying a magnetizing magnetic flux to the permanent magnet, The magnetizing device includes, as the yoke portion, a first yoke (32) arranged on the outer diameter side of the rotor, and a second yoke (34, 42) arranged on the axial side of the rotor, magnetically coupled to the first yoke, and having an insertion protrusion (34d, 42d) inserted into a shaft insertion hole (22b) of the rotor, and also includes magnetizing coils (33, 35, 43) provided on magnetic paths of the first and second yokes, the magnetizing coil is energized to cause the magnetizing magnetic flux to flow between the insertion protrusions of the first yoke and the second yoke, which are opposed to each other in the radial direction of the rotor, thereby magnetizing the permanent magnet; The first yoke is mainly composed of a steel plate laminate (A11), and the steel plate laminate has a function of suppressing eddy currents that may be generated by the magnetizing magnetic flux; the second yoke is mainly composed of a powder magnetic core (A12, A14), and the powder magnetic core has a function of suppressing eddy currents that may be generated by the magnetizing magnetic flux; and the insertion protrusion of the second yoke is composed of a steel material (A13, A15). Rotor manufacturing equipment.

2. the second yokes are disposed on one axial side and the other axial side of the first yoke, respectively, and the second yoke on the one axial side is configured to be movable toward and away from the first yoke, A steel plate (A16) is attached to a contact portion of the second yoke on one axial side with the first yoke. The rotor manufacturing apparatus according to claim 1 .

3. The first yoke has an opposing surface (32a1) that faces the outer circumferential surface (22a) of the rotor, A slit (32c) having a function of suppressing eddy currents that may be generated by the magnetizing magnetic flux is formed on the opposing surface. The rotor manufacturing apparatus according to claim 1 or 2.

4. the insertion protrusion of the second yoke has an opposing surface (34d1, 42d1) that faces an inner circumferential surface of the shaft insertion hole of the rotor, The opposing surfaces are formed with slits (34e, 42e) having a function of suppressing eddy currents that may be generated by the magnetizing magnetic flux. The rotor manufacturing apparatus according to any one of claims 1 to 3.

5. A method for manufacturing a rotor having permanent magnets embedded in magnet accommodating holes in a rotor core and having a convex folded shape on the radially inward side, the method comprising magnetizing the embedded permanent magnets from the outside of the rotor using a magnetizing device, the magnetizing device includes a first yoke arranged on the outer diameter side of the rotor, a second yoke arranged on the axial side of the rotor, magnetically coupled to the first yoke, and having an insertion protrusion to be inserted into a shaft insertion hole of the rotor, and a magnetizing coil provided on a magnetic path of the first and second yokes, the first yoke and the second yoke are configured using at least one of a powder magnetic core, a steel plate laminate, and a slit, each of which has a function of suppressing eddy currents that may be generated by magnetizing magnetic flux; an installation step of inserting an insertion portion of the second yoke into a shaft insertion hole of the rotor, arranging radially inner and outer sides of the rotor to face the first yoke and the second yoke in a radial direction, and magnetically connecting the first yoke, the second yoke, and the rotor; a magnetizing step of passing a magnetizing magnetic flux through the rotor based on the energization of the magnetizing coil, thereby magnetizing the embedded permanent magnet.

6. A rotor manufactured by the rotor manufacturing method according to claim 5, the permanent magnet is embedded in the magnet accommodating hole of the rotor core and has a folded shape that is convex on the inside in the radial direction, and the embedded permanent magnet is magnetized from the outside using the magnetizing device, A rotor in which the permanent magnets have a deep folded shape such that the embedded depth is greater than the pole pitch, where the pole pitch is the distance between the extension lines of the inner surfaces of the folded permanent magnets on the outer peripheral surface of the rotor core, and the embedded depth is the distance from the outer peripheral surface of the rotor core to the inner surface of the bent portion of the permanent magnet on the circumferential center line of the permanent magnet.

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