Rotor and method for manufacturing rotor

Abstract

To provide a rotor capable of facilitating identification of a permanent magnet in a state of being attached to a rotor core, and a method of manufacturing the rotor.SOLUTION: The rotor 10 includes a rotor core 20 and a permanent magnet 30. The rotor core 20 is provided with a magnet insertion hole 20b extending in the axial direction X. The permanent magnets 30 have the exposed end surfaces 31 exposed to the outside of the rotor core 20 in the axial direction X while being inserted into the 20b of the magnet insertion hole. The permanent magnet 30 has a groove 33 on the exposed end surface 31. Accordingly, in the rotor 10, it is possible to determine whether or not a desired permanent magnet 30 is attached to the rotor core 20 after the permanent magnet 30 is attached to the rotor core 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotor and a method for manufacturing a rotor. [Background technology]

[0002] Conventionally, rotors equipped with permanent magnets have been known as rotors used in motors. For example, Patent Document 1 discloses a permanent magnet rotor in which permanent magnets are inserted into magnet insertion holes provided in a rotor core. In the permanent magnet rotor, the permanent magnets have marks painted on their end faces exposed from the rotor core that indicate the magnetization direction of the permanent magnets. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-242456 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the paint applied to the permanent magnets may deteriorate depending on the environment in which the rotor is used. For example, if the paint is applied to identify the type of permanent magnet, deterioration of the paint during the rotor manufacturing process may make it difficult to identify the permanent magnets using the markers. [Means for solving the problem]

[0005] The rotor for solving the above problem is a rotor having a rotor core with a magnet insertion hole extending in the axial direction, and a permanent magnet that is inserted into the magnet insertion hole and has an exposed end surface that is exposed to the outside of the rotor core in the axial direction, and the permanent magnet has a groove portion in the exposed end surface.

[0006] According to this, the permanent magnet is inserted into the magnet insertion hole while exposing its exposed end surface to the outside of the rotor core. For example, by providing a groove with an identification function related to the installation in the permanent magnet to be attached to the rotor core, the worker attaching the permanent magnet to the rotor core can use the groove as a marker. The worker can determine whether the desired permanent magnet has been attached to the rotor core after the permanent magnet has been attached to the rotor core. In other words, unlike, for example, a case in which the permanent magnet has a groove on a surface other than the exposed end surface, the rotor allows the permanent magnet to be identified even when attached to the rotor core.

[0007] Furthermore, in permanent magnets where the markings are provided by grooves, the markings are less likely to deteriorate than in permanent magnets where the markings are provided by painting, for example. In other words, the rotor reduces the possibility that the markings will deteriorate during the rotor manufacturing or use process, making it difficult to identify the permanent magnets. As described above, the rotor makes it easy to identify the permanent magnets when attached to the rotor core.

[0008] In the rotor, the magnet insertion hole penetrates the rotor core in the axial direction, and the permanent magnet has the exposed end face at each of both ends in the axial direction, and each of the exposed end faces has the groove portion.

[0009] According to this, the exposed end faces of the permanent magnets are exposed at both axial ends of the rotor core. For example, consider a case where the grooves of the permanent magnets are checked only at one of the two ends of the rotor core. Even in this case, with a permanent magnet of the above configuration, there is no need to adjust the insertion direction so that the grooves are exposed at that end of the rotor core. Therefore, the worker who attaches the permanent magnet to the rotor core can omit the process of aligning the insertion direction of the permanent magnet into the rotor core. In other words, the rotor is manufactured more efficiently than when the permanent magnets have grooves only at one end.

[0010] In the rotor, the exposed end surface has a shape having a pair of edges extending longitudinally when viewed in the axial direction, the permanent magnet is plate-shaped with a thickness direction perpendicular to the axial direction and the longitudinal direction, and the groove portion extends linearly from one of the edges to the other edge.

[0011] One method for forming grooves in permanent magnets is to arrange multiple permanent magnets parallel to one another so that their thickness directions are aligned, and then form grooves in the exposed end faces of the multiple permanent magnets with their exposed end faces facing the same direction. In this case, by forming a linear groove across the entire length of the aligned exposed end faces, grooves can be formed in the exposed end faces of each permanent magnet at once. In other words, the rotor makes it easy to form grooves in the permanent magnets.

[0012] In the rotor, the depth of the groove in the axial direction may be 2 μm or more and 200 μm or less. By making the grooves the above depth, it is possible to provide the permanent magnet with grooves that function as markers while suppressing the reduction in magnetic properties of the permanent magnet that would otherwise occur due to the reduction in volume caused by the grooves.

[0013] In the rotor, the permanent magnet may have a plurality of the grooves arranged in parallel in the longitudinal direction. According to this, the permanent magnets are identified based on the multiple grooves. Therefore, even if a defect occurs in one of the multiple grooves, the permanent magnets can still be identified based on the remaining grooves. In other words, even if a defect occurs in the exposed end surface of the rotor, the permanent magnets can still be identified based on the grooves.

[0014] In the rotor, the grooves may be formed by processing the exposed end surface with a laser. This allows the grooves to be adjusted with higher precision than when the grooves are formed by cutting the permanent magnet, for example.

[0015] In the rotor, the permanent magnet may have a coating on a portion of the exposed end surface that is different from the groove portion. According to this, the permanent magnet has a coating on the portion of the exposed end surface where the groove is not formed. As a result, the groove is exposed to the outside of the coating. In other words, the permanent magnet can prevent the groove from being buried by the coating. The permanent magnet can prevent the groove from being buried by the coating, which makes it difficult to identify the permanent magnet using the groove. As a result, the rotor can make it easy to identify the permanent magnet when it is attached to the rotor core.

[0016] In the rotor, the permanent magnet may have a plurality of the grooves, and the coating may be provided on the exposed end surface between two adjacent grooves. According to this, the permanent magnet has a coating between two adjacent grooves on the exposed end surface while exposing the grooves to the outside of the coating. For example, compared to a case where the permanent magnet does not have a coating between two adjacent grooves on the exposed end surface, the permanent magnet can expose the grooves to the outside of the coating while suppressing a reduction in the area of ​​the portion of the exposed end surface covered by the coating.

[0017] In order to solve the above problem, a method for manufacturing a rotor includes a rotor core having a magnet insertion hole extending in the axial direction, and a permanent magnet that is inserted into the magnet insertion hole and has an exposed end surface that is exposed to the outside of the rotor core in the axial direction, and the method includes a film formation process for forming a film on the exposed end surface, and a groove formation process for forming a groove portion on the exposed end surface, and the groove formation process is performed after the film formation process.

[0018] According to this, by performing the groove forming process after the coating forming process, the grooves are formed in the permanent magnet while leaving the coating on portions of the exposed end surface different from the grooves. Compared to when the groove forming process is performed before the coating process, the rotor manufacturing method can prevent the coating from covering the grooves. In other words, even if the permanent magnets in the rotor have coatings, it is possible to prevent the grooves from being covered by the coating, making it difficult to identify the permanent magnets. As a result, the rotor manufacturing method can manufacture a rotor in which the permanent magnets are easily identified when attached to the rotor core.

[0019] In the method for manufacturing a rotor, the grooves may be formed by a laser in the groove forming step. According to this method, the grooves are formed by irradiating the exposed end surfaces of the permanent magnets with a laser, which allows for more accurate adjustment of the groove depth than when the grooves are formed in the permanent magnets by, for example, grinding. [Effects of the Invention]

[0020] According to the present invention, it is possible to easily identify permanent magnets when they are attached to a rotor core. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a perspective view showing a rotor. [Figure 2] FIG. 2 is a perspective view showing a permanent magnet. [Figure 3] FIG. 3 is an enlarged perspective view showing the exposed end surface. [Figure 4] FIG. 4 is an enlarged perspective view showing the groove portion. [Figure 5] FIG. 5 is a schematic diagram showing a method for forming a groove using a laser device. [Figure 6] FIG. 6 is a perspective view showing a permanent magnet and a coating. [Figure 7] FIG. 7 is a perspective view showing the permanent magnet, the coating, and the gap. [Figure 8]FIG. 8 is an enlarged side view showing the grooves and gaps. DETAILED DESCRIPTION OF THE INVENTION

[0022] [First embodiment] An embodiment of the rotor will be described below with reference to FIGS. <Overall view of the rotor> As shown in Fig. 1, the rotor 10 has a rotor core 20 and a permanent magnet 30. The rotor 10, together with a motor case, a stator, and a shaft (not shown), constitutes a motor. The motor in this embodiment is mounted on a vehicle.

[0023] <Rotor core> The rotor core 20 has a cylindrical shape extending in the axial direction X. The rotor core 20 is formed by a plurality of laminated steel plates (not shown) stacked in the axial direction X.

[0024] The rotor core 20 has a shaft insertion hole 20a. The shaft insertion hole 20a extends along the axial direction X of the rotor core 20. The shaft insertion hole 20a penetrates the rotor core 20 in the axial direction X. The shaft insertion hole 20a penetrates a central portion of the rotor core 20. A shaft (not shown) is inserted into the shaft insertion hole 20a. The shaft is configured to rotate integrally with the rotor core 20.

[0025] The rotor core 20 has a plurality of magnet insertion holes 20b. In other words, the rotor core 20 is provided with magnet insertion holes 20b. In this embodiment, the rotor core 20 has ten magnet insertion holes 20b. The magnet insertion holes 20b open radially outward of the rotor core 20 than the shaft insertion holes 20a. In other words, the magnet insertion holes 20b are formed radially outward of the rotor core 20 than the shaft insertion holes 20a. The magnet insertion holes 20b penetrate the rotor core 20 in the axial direction X.

[0026] The magnet insertion hole 20b has a rectangular shape when viewed from the axial direction X. More specifically, the cross-sectional shape of the magnet insertion hole 20b when cut in a direction perpendicular to the axial direction X is also rectangular. The multiple magnet insertion holes 20b are arranged such that the longitudinal direction of each magnet insertion hole 20b is perpendicular to the radial direction of the rotor core 20 when viewed from the axial direction X, and the magnet insertion holes 20b are spaced apart in the circumferential direction of the rotor core 20. The multiple magnet insertion holes 20b are also arranged so as to be equally spaced apart in the circumferential direction of the rotor core 20. In this embodiment, the rotor core 20 has ten magnet insertion holes 20b.

[0027] <Permanent magnet> The rotor 10 has a plurality of permanent magnets 30. The permanent magnets 30 are plate-shaped. Each of the plurality of permanent magnets 30 is inserted into a magnet insertion hole 20b and fixed to the rotor core 20 by a resin (not shown). In other words, the permanent magnets 30 are inserted into the magnet insertion holes 20b. In this embodiment, ten permanent magnets 30 are provided in the rotor core 20.

[0028] As shown in Fig. 2, the permanent magnet 30 has exposed end faces 31 at both ends in the axial direction X. In other words, the permanent magnet 30 has two exposed end faces 31. In the permanent magnet 30, one exposed end face 31 is the opposite face in the axial direction X to the other exposed end face 31. Note that Fig. 1 shows only one of the two exposed end faces 31.

[0029] As shown in FIG. 1, the permanent magnet 30 is provided in the rotor core 20 with its exposed end face 31 exposed to the outside of the rotor core 20. In other words, the permanent magnet 30 has an exposed end face 31 exposed to the outside of the rotor core 20 in the axial direction X. Also, as shown in FIG. 2, the permanent magnet 30 has four magnet side faces 32 on its outer surface, which are different from the exposed end face 31. In the permanent magnet 30, two exposed end faces 31 are connected via the four magnet side faces 32. The outer surface of the permanent magnet 30 is composed of the two exposed end faces 31 and the four magnet side faces 32.

[0030] The permanent magnet 30 is provided in the rotor core 20 with the magnet side surface 32 facing the surface that defines the magnet insertion hole 20b into which the permanent magnet 30 is inserted. Therefore, only the exposed end surface 31 of the permanent magnet 30 is exposed to the outside of the rotor core 20.

[0031] 1 and 2, the exposed end surface 31 is a rectangular surface perpendicular to the axial direction X. In other words, the exposed end surface 31 is rectangular. More specifically, as shown in FIG. 2, the exposed end surface 31 has a shape having a pair of edges 311 extending in the longitudinal direction D when viewed in the axial direction X. The permanent magnet 30 is plate-shaped and has a thickness direction T perpendicular to the axial direction X and the longitudinal direction D. In other words, the longitudinal direction D is a direction perpendicular to the axial direction X and the thickness direction T of the permanent magnet 30.

[0032] <Groove> As shown in Fig. 2, the permanent magnet 30 has a groove 33 on the exposed end surface 31. The permanent magnet 30 has the groove 33 in a groove region R of the exposed end surface 31. The groove region R is a region of the exposed end surface 31 that corresponds to a central portion in the longitudinal direction D. The groove region R also extends along the thickness direction T from one edge 311 to the other edge 311 on the exposed end surface 31.

[0033] The permanent magnet 30 has grooves 33 on each of the two exposed end faces 31. As shown in FIG. 3 , the permanent magnet 30 has a plurality of grooves 33 on each exposed end face 31. The plurality of grooves 33 are formed in a groove region R. In this embodiment, the permanent magnet 30 has 20 grooves 33 on one exposed end face 31.

[0034] In the exposed end surface 31, the groove 33 extends linearly from one edge 311 to the other edge 311. More specifically, the groove 33 extends in a direction perpendicular to the axial direction X and the longitudinal direction D, and both ends of the groove 33 in the extending direction are connected to the edge 311. The groove 33 extends in a direction parallel to the thickness direction T of the permanent magnet 30.

[0035] The multiple grooves 33 are formed in the exposed end surface 31 so as to be parallel to one another. More specifically, the multiple grooves 33 are aligned in the longitudinal direction D so as to be parallel to one another. In other words, the permanent magnet 30 has multiple grooves 33 aligned in parallel to one another in the longitudinal direction D.

[0036] The plurality of grooves 33 are formed on the exposed end surface 31 so that the interval between adjacent grooves 33 is 2 mm. The plurality of grooves 33 are also formed on the exposed end surface 31 so that the width in the longitudinal direction D is 0.1 mm.

[0037] As shown in FIG. 4, the groove 33 is a portion of the exposed end surface 31 that opens toward the outside of the permanent magnet 30. The groove 33 is a portion of the exposed end surface 31 that is recessed from the surrounding area in the axial direction X. In FIG. 4, the distance from a portion of the exposed end surface 31 other than the groove 33 to the deepest portion of the groove 33 is shown as depth H. The depth H is the distance of the groove 33 along the axial direction X. The depth H of the groove 33 is set to be 2 μm or more and 200 μm or less. In other words, the depth H of the groove 33 in the axial direction X is preferably 2 μm or more and 200 μm or less. The depth H is more preferably 2 μm or more and 100 μm or less, and even more preferably 2 μm or more and 30 μm or less.

[0038] <Method of forming grooves and method of identifying permanent magnets> 5, the grooves 33 are formed in the permanent magnet 30 by a laser device 40. The laser device 40 is configured to irradiate the exposed end surface 31 of the permanent magnet 30 with a laser beam L and to cut out a portion of the permanent magnet 30 by this irradiation. In other words, the grooves 33 are formed by processing the exposed end surface 31 with the laser beam L.

[0039] 5, a method for forming grooves 33 in a permanent magnet 30 using a laser device 40 will be described. The laser device 40 forms grooves 33 in each of a plurality of permanent magnets 30. All of the plurality of permanent magnets 30 have the same shape. More specifically, all of the permanent magnets 30 discussed below have the same dimensions in the axial direction X, the longitudinal direction D, and the thickness direction T.

[0040] First, a plurality of permanent magnets 30 without grooves 33 are arranged in the thickness direction T so as to be parallel to each other. Here, the plurality of permanent magnets 30 are arranged so that each of the two edges extending in the longitudinal direction D of a permanent magnet 30 is on the same straight line as each of the corresponding edges of the other permanent magnets 30. In other words, the plurality of permanent magnets 30 form a machined surface 41 in which the exposed end faces 31 are aligned in the thickness direction T. Two machined surfaces 41 are formed in the axial direction X by the plurality of permanent magnets 30. In the machined surface 41, the exposed end faces 31 of all the permanent magnets 30 face the same direction.

[0041] As shown in FIG. 5 , the laser device 40 irradiates one of the processing surfaces 41 with the laser beam L. In other words, the laser device 40 irradiates one of the exposed end surfaces 31 of the permanent magnets 30 arranged as described above with the laser beam L. Grooves 33 are formed in the exposed end surfaces 31 of the permanent magnets 30 at locations irradiated with the laser beam L. The laser device 40 linearly moves the irradiation position of the laser beam L from one edge to the other edge in the thickness direction T of the processing surface 41. In other words, the laser device 40 linearly moves the location irradiated with the laser beam L in the thickness direction T so as to cross the multiple permanent magnets 30. The laser device 40 irradiates the multiple permanent magnets 30 with the laser beam L 20 times, thereby forming 20 grooves 33 in the multiple permanent magnets 30.

[0042] As described above, the laser device 40 forms grooves 33 on each of the two exposed end surfaces 31 of the permanent magnet 30. In this embodiment, the laser device 40 forms 40 grooves 33 on the permanent magnet 30.

[0043] Next, a method for identifying the permanent magnets 30 in a state where they are attached to the rotor core 20 will be described. The identification is performed so that an operator who manufactures the rotor 10 can determine whether the desired permanent magnets 30 are attached to the rotor core 20.

[0044] The permanent magnets 30 are identified using images captured by a camera (not shown). In this embodiment, the permanent magnets 30 are identified using shape images. Here, the shape image in this specification refers to an image obtained by shining light onto the grooves 33 from multiple angles and combining multiple images taken at each angle. The shape image highlights and displays the unevenness of the exposed end surface 31 caused by the grooves 33. An operator who manufactures the rotor 10 determines whether the permanent magnets 30 have grooves 33 based on the shape image.

[0045] [Effects of this embodiment] The effects and functions of this embodiment will be described below. (1-1) The permanent magnet 30 is inserted into the magnet insertion hole 20b with its exposed end surface 31 exposed to the outside of the rotor core 20. For example, by providing a groove 33 with an identification function related to the installation in advance on the permanent magnet 30 to be attached to the rotor core 20, the worker attaching the permanent magnet 30 to the rotor core 20 can use the groove 33 as a marker. The worker can determine whether the desired permanent magnet 30 has been attached to the rotor core 20 after the permanent magnet 30 has been attached to the rotor core 20. In other words, unlike, for example, when the permanent magnet 30 has a groove 33 on a surface other than the exposed end surface 31, the rotor 10 makes it possible to identify the permanent magnet 30 even when attached to the rotor core 20.

[0046] (1-2) In a permanent magnet 30 in which a mark is provided by the groove 33, the mark is less likely to deteriorate than in a permanent magnet 30 in which the mark is provided by, for example, painting. For example, a rotor 10 used in a motor mounted on a vehicle operates in a higher temperature environment than a motor mounted on an air conditioning system. In a high-temperature environment, a mark provided by paint is more likely to deteriorate than in a low-temperature environment. Therefore, in a rotor 10 used in a motor mounted on a vehicle, by using the groove 33 as the mark instead of paint, deterioration of the mark can be further suppressed. In this way, the rotor 10 can reduce the possibility that the mark will deteriorate during the manufacturing or use process of the rotor 10, making it difficult to identify the permanent magnet 30. As described above, the rotor 10 can facilitate identification of the permanent magnet 30 when attached to the rotor core 20.

[0047] (1-3) The exposed end faces 31 of the permanent magnets 30 are exposed at both ends of the rotor core 20 in the axial direction X. For example, consider a case where the grooves 33 of the permanent magnets 30 are checked at only one of the two ends of the rotor core 20. Even in this case, with the permanent magnets 30 configured as described above, it is not necessary to adjust the insertion direction so that the grooves 33 are exposed at that end of the rotor core 20. Therefore, the worker attaching the permanent magnets 30 to the rotor core 20 can omit the step of aligning the insertion direction of the permanent magnets 30 into the rotor core 20. In other words, the rotor 10 is manufactured more efficiently than when the permanent magnets 30 have grooves 33 at only one end.

[0048] (1-4) In this embodiment, multiple permanent magnets 30 are arranged parallel to one another so that their thickness directions T are aligned, and the exposed end faces 31 of the multiple permanent magnets 30 are arranged facing the same direction, and grooves 33 are formed in these exposed end faces 31. In this case, by forming a linear groove across the entire arrangement direction in the exposed end faces 31 arranged facing the same direction, the grooves 33 can be formed in the exposed end faces 31 of each permanent magnet 30 at once. In other words, the rotor 10 makes it easy to form grooves 33 in the permanent magnets 30.

[0049] (1-5) By setting the depth H of the groove 33 to 2 μm or more and 200 μm or less, it is possible to provide the groove 33 that functions as a marker in the permanent magnet 30 while suppressing the reduction in magnetic properties of the permanent magnet 30 due to volume reduction.

[0050] (1-6) The permanent magnet 30 is identified based on the multiple grooves 33. Therefore, even if a defect or the like occurs in some of the multiple grooves 33, the permanent magnet 30 can remain identifiable based on the other grooves 33. In other words, even if a defect or the like occurs in the exposed end surface 31 of the rotor 10, the permanent magnet 30 can remain identifiable based on the grooves 33.

[0051] (1-7) The grooves 33 are formed in the exposed end surface 31 of the permanent magnet 30 by a laser L. For example, compared to forming the grooves 33 by cutting the permanent magnet 30, the grooves 33 can be adjusted with higher precision.

[0052] [Second embodiment] Hereinafter, one embodiment of a rotor and a method for manufacturing the rotor will be described with reference to FIGS. 1, 5, and 6 to 8. FIG.

[0053] The rotor manufactured by the rotor manufacturing method of this embodiment differs from the rotor 10 of FIG. 1 described in the first embodiment in that the permanent magnets 30 have coatings 50, and gaps 51 are formed in the coatings 50, as shown in FIGS. 7 and 8. Except for this, the rotor of this embodiment has the same configuration as the rotor 10 of FIG. 1. Hereinafter, a description of the same configuration as the rotor 10 described in the first embodiment will be omitted.

[0054] Hereinafter, the rotor of this embodiment will be referred to as rotor 10. In the rotor 10 of this embodiment, the same members as those in the first embodiment will be given the same names and reference numerals. When referring to FIG. 1 in describing this embodiment, the coating 50 and gap 51 shown in FIG. 8 will be omitted from FIG. 1. Furthermore, when referring to FIG. 5 in describing this embodiment, the coating 50, gap 51, and gap region R2 shown in FIG. 8 will be omitted from FIG. 5.

[0055] <Overall view of the rotor> As shown in FIGS. 6 and 7 , the coating 50 is formed to cover the entire surface of the permanent magnet 30. Specifically, the permanent magnet 30 has the coating 50 on the exposed end surface 31 and the four magnet side surfaces 32. The coating 50 is formed, for example, by an oil-based or epoxy resin-based rust-preventive coating. The coating 50 is not limited to being formed by an oil-based or epoxy resin-based rust-preventive coating. The coating 50 may also be, for example, a chemical conversion coating containing zirconium. In short, the coating 50 may be formed on the outer surface of the permanent magnet 30 as a result of a surface treatment performed on the permanent magnet 30. The coating 50 is provided on the permanent magnet 30 for the purpose of improving the rust prevention and corrosion resistance of the permanent magnet 30. Note that in FIGS. 6 to 8 , the coating 50 is indicated by a two-dot chain line, and its thickness is exaggerated for ease of illustration.

[0056] As shown in Fig. 8, a plurality of gaps 51 are formed in the coating 50. The plurality of gaps 51 are formed in the coating 50 on the exposed end surface 31. In Fig. 7, the region of the coating 50 where the plurality of gaps 51 are formed is depicted as a gap region R2. The shape and size of the space corresponding to the gaps 51 shown in Fig. 8 vary depending on the specific shape and size of the coating 50, which is indicated by the two-dot chain line. In Fig. 8, the thickness of the coating 50 is exaggerated, and therefore the size of the space occupied by the gaps 51 in the axial direction X is also exaggerated.

[0057] The gap 51 is formed by cutting out a portion of the coating 50 covering the exposed end surface 31. The gap 51 is formed by cutting out the coating 50 over the entire thickness direction T. Therefore, there is a portion of the exposed end surface 31 that is not covered by the coating 50. The exposed end surface 31 has a portion that is exposed to the outside of the coating 50 due to the gap 51.

[0058] The exposed end surface 31 has portions that are covered with the coating 50 and portions that are not covered with the coating 50. In other words, the exposed end surface 31 has portions that have the coating 50 directly above them and portions that have gaps 51 directly above them. The portions of the exposed end surface 31 that are covered with the coating 50 and the portions that are not covered with the coating 50 are arranged alternately in the longitudinal direction D.

[0059] The permanent magnet 30 has the coating 50 on a portion of the exposed end surface 31 that is different from the groove portion 33. In other words, the permanent magnet 30 has the coating 50 on a portion of the exposed end surface 31 where the groove portion 33 is not formed. The coating 50 covers the portion of the exposed end surface 31 where the groove portion 33 is not formed. Each of the multiple gaps 51 is aligned with the groove portion 33 in the axial direction X.

[0060] The plurality of grooves 33 are aligned in the longitudinal direction D on the exposed end surface 31. Each of the plurality of grooves 33 is formed on the exposed end surface 31 with a gap between adjacent grooves 33 in the longitudinal direction D. The coating 50 is provided on the exposed end surface 31 between two adjacent grooves 33.

[0061] <Rotor manufacturing method> The manufacturing method of the rotor 10 includes a film forming step, a groove forming step, an assembly step, and an inspection step. Each step will be described below.

[0062] <Film formation process> 6, the coating formation process is a process of forming a coating 50 on the outer surface of the permanent magnet 30. Specifically, the coating formation process is a process of forming the coating 50 on the exposed end faces 31 and magnet side faces 32 of the multiple permanent magnets 30.

[0063] The coating process includes an immersion treatment in which the entire permanent magnet 30 is immersed in a solution. In the coating process, the permanent magnet 30 is immersed in the solution, and a coating 50 is formed on the outer surface. The solution used in the coating process contains the components that make up the coating 50. Although a detailed explanation will be omitted, the coating process includes a pre-treatment in which the permanent magnet 30 is degreased and washed before the immersion treatment, and a post-treatment in which the permanent magnet 30 that has been immersed is washed and dried.

[0064] In the coating process, after post-treatment, a coating for improving antifouling properties may be applied to the outer surface of the permanent magnet 30. In this case, the coating 50 includes a thin film formed on the permanent magnet 30 by the coating.

[0065] The coating 50 is formed so as to cover the entire permanent magnet 30. Specifically, the coating 50 covers the exposed end surface 31 and the four magnet side surfaces 32. <Groove formation process> The groove forming process is a process of forming grooves 33 on the exposed end surface 31 of the permanent magnet 30. The groove forming process is performed after the coating forming process. Specifically, the groove forming process is a process of forming a plurality of grooves 33 in the permanent magnet 30 on which the coating 50 has been formed in the coating forming process. In the groove forming process, the grooves 33 are formed by a laser L. In other words, the groove forming process is performed by a laser device 40 shown in FIG. 5. The laser device 40 irradiates the exposed end surface 31 covered with the coating 50 with the laser L. More specifically, the laser device 40 irradiates the exposed end surface 31 of the permanent magnet 30 with the laser L from the axial direction X. The permanent magnet 30 and the coating 50 are cut out by the laser L.

[0066] 8, the permanent magnet 30 and the coating 50 are cut out so as to open in the axial direction X by the laser device 40 shown in FIG. 5. As a result, a groove 33 is formed in the exposed end surface 31 of the permanent magnet 30, and a gap 51 is formed in the coating 50 so as to be aligned with the groove 33 in the axial direction X.

[0067] In the groove forming process, a laser L is used to form grooves 33 in the permanent magnet 30 so that the depth H of the grooves 33 is 2 μm or more and 200 μm or less. The depth H of the grooves 33 does not include the thickness of the coating 50. The depth H of the grooves 33 in the axial direction X is preferably 2 μm or more and 200 μm or less. The depth H is more preferably 2 μm or more and 100 μm or less, and even more preferably 2 μm or more and 30 μm or less. Note that the thickness of the coating 50 is exaggerated in FIG. 8. The thickness of the coating 50 is smaller than the depth H, about 1 μm.

[0068] 5, the groove forming step is performed on a plurality of permanent magnets 30. Note that the method by which the laser device 40 forms the plurality of grooves 33 in the plurality of permanent magnets 30 in the groove forming step is the same as the method described in the first embodiment, except that the method is performed in a state in which the permanent magnets 30 have coatings 50. Therefore, a detailed description of the method by which the laser device 40 forms the grooves 33 and gaps 51 in the plurality of permanent magnets 30 in the groove forming step will be omitted.

[0069] <Assembly process and inspection process> The assembling process is a process of assembling the permanent magnet 30 with the groove 33 formed therein to the rotor core 20 shown in Fig. 1. The assembling process is performed after the groove forming process. In the assembling process, the permanent magnet 30 is assembled into the magnet insertion hole 20b of the rotor core 20 with the exposed end surface 31 exposed to the outside of the rotor core 20.

[0070] The inspection process is a process in which an operator who manufactures the rotor 10 identifies the permanent magnets 30 while they are attached to the rotor core 20. The inspection process is performed to determine whether the desired permanent magnets 30 are attached to the rotor core 20. Note that the method by which the operator identifies the permanent magnets 30 in the inspection process is the same as the method for identifying the permanent magnets 30 described in the first embodiment, except that the permanent magnets 30 have gaps 51 in the coating 50. Therefore, a detailed description of the method for identifying the permanent magnets 30 in the inspection process will be omitted.

[0071] [Effects of this embodiment] The effects and functions of this embodiment will be described below. (2-1) The manufacturing method of the rotor 10 includes a coating forming process and a groove forming process. By performing the groove forming process after the coating process, the grooves 33 are formed in the permanent magnets 30 while leaving the coating 50 on the portions of the exposed end surfaces 31 where the grooves 33 are not formed. Compared to when the groove forming process is performed before the coating process, the manufacturing method of the rotor 10 can prevent the coating 50 from covering the grooves 33. In other words, even if the permanent magnets 30 in the rotor 10 have the coating 50, it is possible to prevent the coating 50 from covering the grooves 33, making it difficult to identify the permanent magnets 30. As described above, the manufacturing method of the rotor 10 can manufacture a rotor 10 in which the permanent magnets 30 are easily identified when attached to the rotor core 20.

[0072] (2-2) The manufacturing method of the rotor 10 forms the grooves 33 by irradiating the exposed end surface 31 of the permanent magnet 30 with a laser L. The manufacturing method of the rotor 10 allows for more accurate adjustment of the depth H of the grooves 33 than when the grooves 33 are formed on the permanent magnet 30 by, for example, grinding.

[0073] (2-3) The permanent magnet 30 has the coating 50 on the portion of the exposed end surface 31 where the grooves 33 are not formed, and the grooves 33 are exposed to the outside of the coating 50. This prevents the grooves 33 of the permanent magnet 30 from being buried by the coating 50. In other words, the permanent magnet 30 prevents the grooves 33 from being buried by the coating 50, making it difficult to identify the permanent magnet 30 using the grooves 33. As described above, by having the coating 50 on a portion of the exposed end surface 31 different from the grooves 33, the rotor 10 can easily identify the permanent magnet 30 when attached to the rotor core 20.

[0074] (2-4) The permanent magnet 30 has the coating 50 between two adjacent grooves 33 on the exposed end face 31, while exposing the grooves 33 to the outside of the coating 50. For example, consider a case where the permanent magnet 30 has multiple grooves 33 on the exposed end face 31, but does not have the coating 50 between the two adjacent grooves 33. Compared to this case, the permanent magnet 30 can expose the grooves 33 to the outside of the coating 50 while suppressing a reduction in the area of ​​the portion of the exposed end face 31 covered by the coating 50. Therefore, the rotor 10 can easily identify the permanent magnet 30 by the multiple grooves 33, while suppressing a reduction in the rust resistance of the permanent magnet 30 due to the coating 50.

[0075] [Example of change] The above-described embodiments can be modified as follows: The above-described embodiments and the following modifications can be combined with each other within the scope of technical compatibility.

[0076] The grooves 33 may be formed in the exposed end surface 31 by a method other than using the laser L. For example, the grooves 33 may be formed by grinding the exposed end surface 31. The grooves 33 do not have to be arranged in parallel in the longitudinal direction D. For example, the grooves 33 may intersect with each other on the exposed end surface 31.

[0077] The depth H of the groove 33 may be less than 2 μm. The depth H of the groove 33 may be greater than 200 μm. In short, the depth H of the groove 33 may be within a range that can be displayed by a shape image.

[0078] The distance between adjacent grooves 33 on the exposed end surface 31 is not limited to that described above. Two of the grooves 33 on the exposed end surface 31 may have their edges in the longitudinal direction D connected to each other.

[0079] The number of grooves 33 is not limited to 20. Furthermore, the permanent magnet 30 does not have to have a plurality of grooves 33. In other words, the permanent magnet 30 only needs to have one or more grooves 33.

[0080] The groove 33 does not have to extend linearly. For example, the groove 33 may extend in a curved manner from one edge 311 to the other edge 311. The groove 33 may have one end connected to the edge 311 extending in the longitudinal direction D, and the other end connected to an edge extending in a direction perpendicular to the longitudinal direction D.

[0081] The groove 33 does not have to extend linearly from one edge 311 to the other edge 311. For example, the groove 33 may extend from one edge to the other edge of a pair of edges of the exposed end surface 31 that extend in a direction perpendicular to the longitudinal direction D. In other words, the groove 33 may extend in the longitudinal direction D.

[0082] The exposed end surface 31 does not have to be rectangular. For example, the exposed end surface 31 may be a parallelogram having a pair of edges 311 extending in the longitudinal direction D. The shapes of the permanent magnets 30 and the exposed end faces 31 are not limited to those described in the embodiment. For example, the permanent magnets 30 may be columnar, with the exposed end faces 31 extending along the circumferential direction of the rotor core 20 as end faces in the axial direction X. In this case, the shape of the magnet insertion holes 20b is changed as appropriate to match the shape of the permanent magnets 30.

[0083] The grooves 33 do not have to be provided at both ends of the permanent magnet 30 in the axial direction X. In this case, it is preferable to adjust the insertion direction of the permanent magnet 30 into the magnet insertion hole 20b so that the grooves 33 are exposed from the same end of the rotor core 20.

[0084] The motor including the rotor 10 does not have to be mounted on a vehicle. The motor may be mounted anywhere. The exposed end surfaces 31 refer to end surfaces exposed from the rotor core 20 and may be covered by other components such as end plates. In short, it is sufficient that the exposed end surfaces 31 of the permanent magnets 30 are not covered by the rotor core 20.

[0085] The entire portion of the exposed end surface 31 of the permanent magnet 30 that corresponds to the groove region R does not have to be covered with the coating 50. More specifically, the portion of the exposed end surface 31 of the permanent magnet 30 that is between two adjacent groove portions 33 does not have to be covered with the coating 50. In this case, the permanent magnet 30 has the coating 50 only on a portion of the exposed end surface 31 that is closer to the edge extending in a direction perpendicular to the longitudinal direction D. In short, it is sufficient that the coating 50 is provided on a portion of the exposed end surface 31 that is different from the groove portions 33.

[0086] In the groove forming step, the grooves 33 may be formed in the exposed end surface 31 by a method other than using the laser L. For example, the grooves 33 may be formed by grinding the exposed end surface 31 in the groove forming step.

[0087] The manufacturing method of the rotor 10 may include a step of performing some kind of processing on the permanent magnets 30 after the coating formation step and before the groove formation step. In short, in the manufacturing method of the rotor 10, the groove formation step may be performed after the coating formation step, and does not have to be performed immediately after the coating formation step. An example of the above-mentioned step of performing some kind of processing on the permanent magnets 30 is a step of measuring the thickness of the coating 50 formed on the permanent magnets 30.

[0088] In the coating formation step, the coating 50 may be formed on the permanent magnet 30 by a method other than impregnating the permanent magnet 30 in a solution. For example, the coating 50 may be formed on the permanent magnet 30 by spraying a solution onto the permanent magnet 30. In short, the coating 50 may be formed by surface treatment of the permanent magnet 30.

[0089] In the coating formation step, the coating 50 may be formed only on the exposed end surface 31. In other words, the coating 50 does not have to be formed on the four magnet side surfaces 32 in the coating formation step. In the inspection process, the permanent magnets 30 attached to the rotor core 20 may be identified visually by an operator who manufactures the rotor 10. Specifically, whether or not the desired permanent magnets 30 are attached to the rotor core 20 may be determined by the operator who manufactures the rotor 10 directly visually inspecting the permanent magnets 30. In the second embodiment, the permanent magnets 30 have the grooves 33 exposed to the outside of the coating 50 through the gaps 51, and the coating 50 is provided in a portion different from the grooves 33. In other words, as viewed by the operator, there is a difference in color between the grooves 33 and the coating 50 on the exposed end surface 31 of the permanent magnet 30. Therefore, since the permanent magnets 30 have the coating 50 in a portion different from the grooves 33, the operator can more easily visually identify the permanent magnets 30 than if the coating 50 covered the grooves 33.

[0090] [Note] The technical ideas that can be understood from the above-described embodiments and modifications will be described below. <Appendix 1> A rotor having a rotor core with a magnet insertion hole extending in the axial direction, and a permanent magnet inserted into the magnet insertion hole and having an exposed end surface exposed to the outside of the rotor core in the axial direction, wherein the permanent magnet has a groove portion in the exposed end surface.

[0091] <Appendix 2> 2. The rotor of claim 1, wherein the magnet insertion hole penetrates the rotor core in the axial direction, and the permanent magnet has the exposed end face at each of both ends in the axial direction, and the exposed end face has the groove portion.

[0092] <Appendix 3> 3. The rotor according to claim 1, wherein the exposed end surface has a shape having a pair of edges extending in the longitudinal direction when viewed in the axial direction, the permanent magnet is a plate having a thickness direction perpendicular to the axial direction and the longitudinal direction, and the groove extends linearly from one of the edges to the other of the edges.

[0093] <Appendix 4> 4. The rotor according to claim 1, wherein the depth of the groove in the axial direction is not less than 2 μm and not more than 200 μm.

[0094] <Appendix 5> 5. The rotor according to claim 1, wherein the permanent magnet has a plurality of the grooves arranged in parallel in the longitudinal direction.

[0095] <Appendix 6> 6. The rotor according to claim 1, wherein the groove is formed by processing the exposed end surface with a laser.

[0096] <Appendix 7> 7. The rotor according to claim 1, wherein the permanent magnet has a coating on a portion of the exposed end surface that is different from the groove.

[0097] <Appendix 8> 8. The rotor according to claim 7, wherein the permanent magnet has a plurality of the grooves, and the coating is provided on the exposed end surface between two adjacent grooves. [Explanation of symbols]

[0098] 10...rotor, 20...rotor core, 20b...magnet insertion hole, 30...permanent magnet, 31...exposed end surface, 33...groove portion, 311...edge portion, 50...coating, D...longitudinal direction, H...depth, L...laser, T...thickness direction, X...axial direction.

Claims

1. a rotor core provided with magnet insertion holes extending in the axial direction; a permanent magnet inserted into the magnet insertion hole and having an exposed end surface exposed to the outside of the rotor core in the axial direction, The rotor is characterized in that the permanent magnet has a groove on the exposed end surface.

2. the magnet insertion hole penetrates the rotor core in the axial direction, The rotor according to claim 1 , wherein the permanent magnet has the exposed end surface at each of both ends in the axial direction, and the groove is formed in each of the exposed end surfaces.

3. The exposed end surface has a shape having a pair of edges extending in a longitudinal direction when viewed in the axial direction, the permanent magnet is plate-shaped and has a thickness direction perpendicular to the axial direction and the longitudinal direction, 3. The rotor according to claim 1, wherein the groove extends linearly from one edge portion to the other edge portion.

4. 3. The rotor according to claim 1, wherein the depth of the groove in the axial direction is not less than 2 [mu]m and not more than 200 [mu]m.

5. The rotor according to claim 3 , wherein the permanent magnet has a plurality of the grooves arranged in parallel in the longitudinal direction.

6. 3. The rotor according to claim 1, wherein the groove is formed by processing the exposed end surface with a laser.

7. 3. The rotor according to claim 1, wherein the permanent magnet has a coating on a portion of the exposed end surface different from the groove portion.

8. the permanent magnet has a plurality of the grooves, The rotor according to claim 7 , wherein the coating is provided on the exposed end surface between two adjacent grooves.

9. a rotor core provided with magnet insertion holes extending in the axial direction; a permanent magnet that is inserted into the magnet insertion hole and has an exposed end surface that is exposed to the outside of the rotor core in the axial direction, a coating forming step of forming a coating on the exposed end surface; a groove forming step of forming a groove on the exposed end surface, The method for manufacturing a rotor, wherein the groove forming step is performed after the film forming step.

10. The method for manufacturing a rotor according to claim 9 , wherein in the groove forming step, the grooves are formed by a laser.

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