Rotor manufacturing method and rotor

Abstract

[Problem] To provide a technique for preventing a resin ingress into an unintended portion. [Solution] This rotor manufacturing method comprises: a magnet preparation step of preparing a plurality of permanent magnets; a rotor core preparation step of preparing an annular rotor core including a plurality of magnet accommodation holes penetrating in an axial direction and accommodating at least one of the plurality of permanent magnets; a molding step of performing molding for integrating a resin with each of the plurality of permanent magnets; and an insertion step of inserting the integrated resin and permanent magnets respectively into the magnet accommodation holes. The molding step is configured to include a step of molding the resin such that when the magnet accommodation hole is viewed along the axial direction, the resin is present in a part of a region formed between the permanent magnet and an inner wall of the magnet accommodation hole, and the region for a refrigerant is present in at least a part of the remainder of the region.

Description

Rotor manufacturing method and rotor

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

[0002] Conventionally, there is known a technology in which a permanent magnet and a resin are accommodated in a magnet accommodation hole provided in a rotor core, and the permanent magnet is fixed to the magnet accommodation hole by the resin. For example, Patent Document 1 discloses a technology in which a permanent magnet is accommodated in a magnet accommodation hole, a resin material is filled into a gap of the magnet accommodation hole with a rod-shaped mold inserted, and after the resin material is cured, the mold is pulled out to form a passage.

[0003] Japanese Unexamined Patent Application Publication No. 2009-303293

[0004] In the conventional technology, after a permanent magnet is accommodated in a magnet accommodation hole, the magnet accommodation hole is filled with resin and the resin is cured. In such a configuration where resin is filled into the magnet accommodation hole after the permanent magnet is accommodated therein, the resin may enter unintended regions. For example, uncured liquid resin may enter gaps between electromagnetic steel sheets constituting the rotor core. In this case, the resin exerts a force that separates the electromagnetic steel sheets from each other. The present invention has been made in view of the above problem, and an object of the present invention is to provide a technology that prevents resin from entering unintended regions.

[0005] A rotor manufacturing method according to one embodiment comprises: a magnet preparation step of preparing a plurality of permanent magnets; a rotor core preparation step of preparing an annular rotor core that has a plurality of magnet accommodation holes penetrating in the axial direction and each accommodating at least one of the plurality of permanent magnets; a molding step of performing molding to integrate resin with each of the plurality of permanent magnets; and an insertion step of inserting each of the integrated resin and the integrated permanent magnet into the corresponding magnet accommodation hole, wherein the molding step includes molding the resin such that when the magnet accommodation hole is viewed along the axial direction, the resin is present in a part of a region formed between the permanent magnet and an inner wall of the magnet accommodation hole, and the region for a coolant is present in at least a part of the remainder of the region.

[0006] In other words, before housing the permanent magnet in the magnet housing hole, the permanent magnet and resin are molded together, and the molded permanent magnet and resin are then inserted into the magnet housing hole. This allows the resin to be molded into the intended shape and prevents the resin from entering unintended areas. For example, in a configuration where the rotor core is made of electromagnetic steel sheets, if resin is filled into the magnet housing hole where the permanent magnet is housed, the uncured resin may enter the gaps between the electromagnetic steel sheets. In this case, once the resin hardens, it will exert a force on the electromagnetic steel sheets that separates them. However, with a configuration in which the permanent magnet and resin are molded together and then the molded permanent magnet and resin are inserted into the magnet housing hole, it is possible to prevent the resin from entering the gaps between the electromagnetic steel sheets.

[0007] Furthermore, a rotor according to one embodiment comprises a plurality of permanent magnets, an annular rotor core having a plurality of magnet housing holes that penetrate in the axial direction and accommodate at least one of the plurality of permanent magnets, and a resin that, when the magnet housing holes are viewed along the axial direction, is present in a part of the region formed between the permanent magnets and the inner walls of the magnet housing holes, thereby forming the region for the coolant in at least the remaining part of the region, wherein the rotor core is composed of a plurality of laminated electromagnetic steel sheets, and the resin does not enter the gaps between the electromagnetic steel sheets in the axial direction.

[0008] In other words, if the permanent magnet and resin are molded integrally before the permanent magnet is placed in the magnet housing hole, and the molded permanent magnet and resin are then inserted into the magnet housing hole, the rotor can be constructed without resin entering unintended areas, namely the gaps between the electromagnetic steel sheets in the axial direction.

[0009] This is a front view of the rotor. This is a plan view showing the rotor core as seen along the axial direction. This is a plan view showing the permanent magnets housed in the magnet housing holes. This is an enlarged view of the magnet housing holes with the permanent magnets and resin housed inside. This is a cross-sectional view showing the rotor core cut along line A-A in Figure 3. This is a cross-sectional view showing the rotor core cut along line B-B in Figure 2. This is a cross-sectional view showing the rotor core cut along line C-C in Figure 3. This is a flowchart showing a method for manufacturing the rotor. Figure 9A shows an example of a mold, Figure 9B shows a state in which permanent magnets are arranged in the cavity of the mold, and Figure 9C shows a state in which the mold is filled with resin. This is a diagram showing an example in which slits are formed in the permanent magnets. This is a diagram showing an example in which the outer circumference of the permanent magnets is covered with resin. This is a cross-sectional view of a rotor core according to another embodiment. This is a cross-sectional view of a rotor core according to another embodiment.

[0010] Here, embodiments of the present invention will be described in the following order: (1) Rotor configuration; (2) Rotor manufacturing method; (3) Other embodiments, etc.

[0011] (1) Rotor configuration: Figure 1 is a front view of the rotor 1 according to this embodiment. The rotor 1 is a member that is arranged in a space formed radially inside the stator core (not shown) and rotates with the rotation axis Ax as the center of rotation. In this specification, the direction parallel to the rotation axis Ax is called the axial direction, the direction perpendicular to the rotation axis Ax is called the radial direction, and the direction of rotation around the rotation axis Ax is called the circumferential direction. Furthermore, in the radial direction, the direction away from the rotation axis Ax is called the radially outward direction, and the direction approaching the rotation axis Ax is called the radially inward direction. Figure 1 is a diagram showing the rotor 1 as viewed along the radial direction.

[0012] The rotor 1 comprises a rotor core 10 and a shaft 20. The shaft 20 is a hollow cylindrical member that rotates around the rotation axis Ax. The rotor core 10 is attached to the shaft 20 and rotates together with the shaft 20 around the rotation axis Ax.

[0013] In this embodiment, the rotor core 10 is constructed by laminating annular sheet members of a predetermined thickness. In this embodiment, the sheet members are electrical steel sheets. Figure 2 is a plan view of the rotor core 10 constructed by laminating sheet members, viewed along the axial direction. The rotor core 10 is an annular member, and a shaft hole into which a shaft 20 is fitted is formed on the radially inner side. The shape of the shaft hole is not limited to a circle; a key may be formed in the shaft hole, a keyway may be formed in the shaft 20, and the shaft 20 may be fitted into the shaft hole with the key fitted into the keyway.

[0014] The rotor core 10 has magnet housing holes 11 formed therein. In this embodiment, the magnet housing holes 11 are substantially rectangular and extend axially while maintaining the same shape when viewed along the axial direction, penetrating the rotor core 10. That is, each sheet member constituting the rotor core 10 has magnet housing holes 11 of the same shape formed at the same position, and when the sheet members are stacked, the magnet housing holes 11 become holes that penetrate the rotor core 10 in the axial direction.

[0015] The magnet housing hole 11 is a hole in which a permanent magnet that forms a magnetic pole is housed. In this embodiment, one permanent magnet is housed in one magnet housing hole 11. Figure 3 shows the state in which a permanent magnet 12 is housed in the magnet housing hole 11. In this embodiment, since the resin 13 is housed in the magnet housing hole 11 together with the permanent magnet 12, Figure 3 shows the state in which the resin 13 is housed. Also in Figure 3, hatching is applied to the end faces of the permanent magnet 12 and the resin 13.

[0016] In this embodiment, the outer shape of the permanent magnet 12 is rectangular when viewed along the axial direction. The cross-sectional shape of the permanent magnet 12 in the direction perpendicular to the axial direction is the same at any position along the axial direction. Therefore, in this embodiment, the permanent magnet 12 is a rectangular parallelepiped that is elongated in the axial direction.

[0017] In this embodiment, the two nearest magnet housing holes 11 form a pair, and the permanent magnets 12 housed in the paired magnet housing holes 11 form one magnetic pole. Specifically, the magnet housing holes 11 are oriented such that, when viewed along the axial direction, the circumferential length of the long side of the rectangle is greater than the radial length of the long side. Furthermore, the short sides of the rectangles are arranged facing each other, so that two magnet housing holes 11 form a pair. When a permanent magnet 12 is housed in each of the pair of magnet housing holes 11, the magnetic field of the permanent magnets 12 housed in each of the pair forms one magnetic pole. In Figure 3, one of the magnetic poles Mp is indicated by a dashed line.

[0018] In this embodiment, the shape and size of all magnet housing holes 11 are the same, and a set of magnet housing holes 11 is arranged symmetrically with respect to a virtual line L (see Figure 3). Here, the virtual line L is a straight line connecting the rotation axis Ax, which is the center of rotation, and the center of the magnetic pole Mp formed on the rotor core 10 by the permanent magnet 12.

[0019] In this embodiment, when the magnet housing hole 11 is viewed along the axial direction, resin 13 is present in a portion of the region formed between the permanent magnet 12 and the inner wall of the magnet housing hole 11. Figure 4 is an enlarged view of the magnet housing hole 11 in which the permanent magnet 12 and resin 13 are housed. In the example shown in Figure 4, the region formed by the inner wall 11b of the magnet housing hole 11 is a substantially rectangular region. In the example shown in Figure 4, the permanent magnet 12 is located in a rectangular region that is approximately in the center of this region and constitutes a portion of this region. Resin 13 is present in a portion of the remaining region, that is, in the regions at the four corners of the permanent magnet 12 when the permanent magnet 12 is viewed along the axial direction.

[0020] In the region inside the inner wall 11b of the magnet housing hole 11, the regions 14a, 14b, 14c, and 14d, excluding the permanent magnet 12, the resin 13, and the protruding portion 11a (described later), are void. That is, the presence of the resin 13 between the permanent magnet 12 and the inner wall 11b of the magnet housing hole 11 forms regions 14a, 14b, 14c, and 14d.

[0021] As described above, in this embodiment, when the magnet housing hole 11 is viewed along the axial direction, the resin 13 and regions 14a, 14b, 14c, and 14d exist on the outer side of the outer circumference of the permanent magnet 12. In this embodiment, regions 14a, 14b, 14c, and 14d are spaces that are not filled with resin 13. Therefore, when the magnet housing hole 11 is viewed along the axial direction, the resin 13 or space exists between the permanent magnet 12 and the inner wall of the magnet housing hole 11. As a result, the permanent magnet 12 and the magnet housing hole 11 are not in direct contact, and there is no need to insulate the space between the permanent magnet 12 and the inner wall of the magnet housing hole 11. As a result, the work process is simplified and costs are reduced compared to cases where insulation is required.

[0022] In this embodiment, at least a portion of regions 14a, 14b, 14c, and 14d is designated as a region for the refrigerant. In the examples shown in Figures 1 to 4, region 14a is assumed to be the region for the refrigerant, but at least one of regions 14b, 14c, and 14d may also be designated as a region for the refrigerant.

[0023] In this embodiment, the region for the refrigerant is the refrigerant flow path. Specifically, region 14a is a hole that penetrates in the axial direction, and is configured so that a non-conductive liquid refrigerant flows through region 14a. Various configurations can be used to allow the refrigerant to flow through region 14a, which is the refrigerant flow path. Figure 5 is a cross-sectional view showing the rotor core 10 cut along the line A-A shown in Figure 3. However, Figure 5 shows the state in which the shaft 20 is fitted into the rotor core 10.

[0024] As shown in Figure 5, the shaft 20 is a hollow cylindrical member, and a radial refrigerant passage 20a is formed in the axial center. The radial refrigerant passage 20a is a hole that extends radially and is connected to the hollow portion of the shaft 20, passing through the shaft 20 in the radial direction. On the radially outer side of the radial refrigerant passage 20a, a connecting refrigerant passage 10a is formed in the rotor core 10.

[0025] In this embodiment, the connecting refrigerant passage 10a is a hole that connects the radial refrigerant passage 20a and the refrigerant region 14a formed in the magnet housing hole 11. That is, the connecting refrigerant passage 10a is a hole that extends radially from the radially outer end of the radial refrigerant passage 20a in the direction of extension of the radial refrigerant passage 20a. The radially outer end of the connecting refrigerant passage 10a opens into the inner wall 11b of the magnet housing hole 11. Therefore, the connecting refrigerant passage 10a is a hole that connects the radial refrigerant passage 20a and the region 14a. The connecting refrigerant passage 10a is formed by a hole that penetrates axially and extends radially in at least one of the sheet members constituting the rotor core 10. That is, the connecting refrigerant passage 10a is formed by positioning the sheet member in the axial center of the rotor core 10.

[0026] With the above configuration, refrigerant is supplied to the space radially inside the shaft 20, and this refrigerant is supplied to region 14a through the radial refrigerant passage 20a and the connecting refrigerant passage 10a. The refrigerant that reaches region 14a flows toward both ends in the axial direction and is discharged from both ends in the axial direction. As a result, the refrigerant flowing through region 14a can cool the permanent magnet 12 and the rotor core 10.

[0027] In this implementation, the radial refrigerant passage 20a and the connecting refrigerant passage 10a are formed to correspond to each magnet housing hole 11. That is, a connecting refrigerant passage 10a is connected to each of the regions 14a formed in each of the magnet housing holes 11, and the connecting refrigerant passage 10a is connected to the radial refrigerant passage 20a. Therefore, refrigerant is supplied to the regions 14a formed in each of the magnet housing holes 11.

[0028] Furthermore, the magnet housing hole 11 of the rotor core 10 according to this embodiment has protrusions 11a that project from the inner wall 11b of the magnet housing hole 11 toward the resin 13 and are discretely present in the axial direction (see Figures 2 and 4). The protrusions 11a are longer than the distance between the inner wall 11b of the magnet housing hole 11 and the resin 13, and the resin 13 and permanent magnet 12 are held in the magnet housing hole by elastic deformation between the inner wall and the resin 13.

[0029] Specifically, in this embodiment, the protrusion 11a is formed on a part of the sheet members stacked in the axial direction, and not on the remaining sheet members. Figure 6 is a cross-sectional view showing the rotor core 10 cut along the line B-B shown in Figure 2, and Figure 7 is a cross-sectional view showing the rotor core 10 cut along the line C-C shown in Figure 3.

[0030] In the example shown in Figure 6, one out of every four sheet members has a protrusion 11a formed on it, while the remaining three sheet members do not have a protrusion 11a. In this configuration, the protrusions 11a are discretely distributed in the axial direction. The frequency and location of the appearance of the protrusions 11a in the axial direction are not limited, the period during which the protrusions 11a exist in the axial direction does not have to be constant, and the shape and size of the protrusions 11a may differ depending on their position in the axial direction. In the example shown in Figure 6, the thickness of the protrusion 11a in the axial direction is the same as the thickness of the sheet member, but the thickness of the protrusion 11a may be smaller than the thickness of the sheet member.

[0031] As shown in Figures 2, 4, and 6, the protrusion 11a is a portion that protrudes from two locations on the longer side of the rectangle formed by the inner wall 11b of the magnet housing hole 11 when the magnet housing hole 11 is viewed along the axial direction, in a direction parallel to the shorter side. In the direction parallel to the shorter side, the length Lp (see Figure 6) of the protrusion 11a is longer than the distance Lr (see Figure 7) between the inner wall 11b of the magnet housing hole 11 and the resin 13.

[0032] Therefore, when the permanent magnet 12 and the resin 13 are inserted into the magnet housing hole 11 in an integrated state (details of integration and insertion will be described later), the protrusion 11a elastically deforms in the axial direction, as shown in Figure 7, and in this elastically deformed state, the protrusion 11a is located between the inner wall 11b and the resin 13. As a result, an elastic force acts from the protrusion 11a on the resin 13, and the integrated resin 13 and permanent magnet 12 are held in place within the magnet housing hole 11. With this configuration, the integrated resin 13 and permanent magnet 12 can be held within the magnet housing hole 11 without using an adhesive.

[0033] (2) Method for manufacturing the rotor: Next, the method for manufacturing the rotor 1 will be described. Figure 8 is a flowchart showing the method for manufacturing the rotor 1. In this manufacturing method, first, the permanent magnets 12 are prepared (step S100). That is, a plurality of permanent magnets 12 of a predetermined shape and magnetized in a predetermined direction are prepared. Specifically, a rectangular parallelepiped permanent magnet 12 is manufactured in which the axial length is the same as or shorter by a predetermined length than the axial length of the rotor core 10. Furthermore, in the permanent magnet 12, when the permanent magnet 12 is viewed along the axial direction, one of the longer sides of the rectangle is magnetized as the north pole and the other as the south pole. Various known methods can be used for manufacturing the permanent magnets 12 and for cutting them to the desired shape.

[0034] Next, the rotor core 10 is prepared (step S105). That is, the rotor core 10 is prepared by manufacturing and stacking multiple sheet members. The sheet members can be manufactured by known methods, for example, by punching out sheet-shaped electromagnetic steel sheets using a die and punch. When manufacturing multiple sheet members, multiple magnet housing holes 11 of a predetermined shape are formed at predetermined positions in each sheet member. In this embodiment, as described above, one permanent magnet 12 is housed in one magnet housing hole 11.

[0035] Furthermore, multiple sheet members are manufactured such that some of the sheet members have protrusions 11a, while others do not. In addition, a connecting refrigerant passage 10a is formed in some of the sheet members. This connecting refrigerant passage 10a can be formed by punching or the like as described above. The sheet members are then stacked in the axial direction such that some of the sheet members have protrusions 11a, while others do not. When the sheet members are stacked, the stacking order of the sheet members with protrusions 11a and the sheet members without protrusions 11a is set so that the protrusions 11a are discretely present in the axial direction. As a result, a rotor core 10 is prepared in which the protrusions 11a are discretely present in the axial direction, as shown in Figure 6.

[0036] Furthermore, at a predetermined position in the axial center, that is, at the position where the radial refrigerant passage 20a opens, sheet members equipped with connecting refrigerant passages 10a are stacked. Each sheet member can be joined by, for example, forming a crimping projection on one side of the sheet member and a hole for accommodating the projection on the other side, and crimping and fixing the sheet member so that the projection is accommodated in the hole. In this way, each sheet member is joined by various known methods, but in any method, a small gap may be formed between the sheet members in the axial direction.

[0037] Next, a mold is prepared (step S110). Here, the mold is for molding the resin 13 while integrating the permanent magnet 12 and the resin 13. In this embodiment, the mold is a mold in which a cavity is formed, with a part for housing the permanent magnet 12 and a part for filling with resin 13. Figure 9A shows an example of a mold 30. The mold 30 shown in Figure 9A has a cylindrical outer shape that is long in one direction, and a cavity is formed inside. In Figure 9A, the shape of the outer circumference of the mold 30 and the cavity 31 formed inside the mold 30 are shown in a cross-section in a direction perpendicular to the longitudinal direction of the mold 30.

[0038] The cavity 31 has a shape in which protrusions are formed on all four sides of a rectangle when viewed along the axial direction of the cylinder constituting the mold 30 (corresponding to the axial direction of the rotor core 10). That is, the mold 30 has protrusions 31a and 31c that protrude in the direction of the cavity 31 from the central part of the long side of the rectangle constituting the cavity 31. The mold 30 also has protrusions 31b and 31d that protrude in the direction of the cavity 31 from the central part of the short side of the rectangle constituting the cavity 31.

[0039] The surfaces of each protrusion 31a to 31d facing the cavity 31 are flat and are the parts that contact the permanent magnet 12 and position the permanent magnet 12. In addition, the parts of the cavity 31 other than the parts where the permanent magnet 12 is located are the parts that will be filled with resin 13. Specifically, the four corners when the cavity 31 is viewed along the axial direction are the parts that will be filled with resin 13. A resin supply device is attached to the mold 30 so that resin 13 can be filled into each of the parts that will be filled with resin 13 with the permanent magnet 12 in place.

[0040] Next, the resin is molded (step S115). First, the permanent magnet 12 is placed in the cavity 31 of the mold 30. Figure 9B shows the state in which the permanent magnet 12 is placed in the cavity 31 of the mold 30, with the permanent magnet 12 indicated by a hatch. When the permanent magnet 12 is placed in the cavity 31, the protrusions 31a to 31d come into contact with the permanent magnet 12, thereby positioning the permanent magnet 12 within the cavity 31. In this state, the space remaining in the cavity 31 is the area to be filled with resin 13.

[0041] With the permanent magnet 12 positioned in the cavity 31 of the mold 30, the remaining portion of the cavity 31 is filled with resin 13. Figure 9C shows the state in which the mold 30 is filled with resin 13, with the resin 13 indicated by hatches. When the resin 13 hardens, the resin 13 and the permanent magnet 12 become one, and the integrated resin 13 and permanent magnet 12 are removed from the mold 30. Various known configurations can be used for removing the integrated resin 13 and permanent magnet 12 from the mold 30. For example, the mold 30 may be separable, allowing the integrated resin 13 and permanent magnet 12 to be removed by separating it, or the integrated resin 13 and permanent magnet 12 may be removed by moving them longitudinally from one end of the mold 30. The molding of the resin is carried out for multiple permanent magnets 12.

[0042] Next, the integrated resin 13 and the permanent magnet 12 are inserted into the magnet housing holes 11 (step S120). That is, the integrated resin 13 and the permanent magnet 12 are elongated in one direction, and their orientation relative to the magnet housing holes 11 is determined such that this longitudinal direction is the axial direction, and the magnetization direction of the permanent magnet 12 is in a predetermined direction to form magnetic poles. Then, the integrated resin 13 and the permanent magnet 12 are inserted into the magnet housing holes 11.

[0043] As shown in Fig. 4, when viewed along the axial direction, the length in the longitudinal direction of the integrated resin 13 and permanent magnet 12 is substantially equal to the length in the longitudinal direction of the magnet receiving hole 11. The length in the transverse direction of the integrated resin 13 and permanent magnet 12 is shorter than the length in the transverse direction of the magnet receiving hole 11. However, the length in the transverse direction of the protruding portion 11a is longer than the distance in the transverse direction between the resin 13 and the inner wall 11b. Therefore, during the insertion process, the resin 13 comes into contact with the protruding portion 11a and is inserted in the axial direction while elastically deforming the protruding portion 11a. As a result, the protruding portion 11a, which was in the state shown in Fig. 6 before insertion, is brought into an elastically deformed state as shown in Fig. 7 after insertion. Accordingly, an elastic force acts from the protruding portion 11a on the integrated resin 13 and permanent magnet 12, so that the integrated resin 13 and permanent magnet 12 can be held in the magnet receiving hole 11 without using an adhesive or the like.

[0044] As shown in Fig. 9A, the cavity 31 has protruding portions 31a to 31d, and after molding, this portion becomes a region where neither the permanent magnet 12 nor the resin 13 exists. Therefore, when the integrated resin 13 and permanent magnet 12 are inserted into the magnet receiving hole 11, the portion formed by the presence of the protruding portions 31a to 31d becomes a portion where neither the permanent magnet 12 nor the resin 13 exists. That is, it is any one of the regions 14a to 14d shown in Fig. 4. Therefore, it can be said that the regions 14a to 14d are formed by the molding step in the above-mentioned step S115. That is, when the magnet receiving hole 11 is viewed along the axial direction, it can be said that the molding is performed such that the resin 13 exists in a part of the region formed between the permanent magnet 12 and the inner wall 11b of the magnet receiving hole 11, and the remaining portion is a cavity. The region 14a, which is at least a part of the hollow portion, serves as a region for a coolant and serves as a flow path for the coolant.

[0045] As described above, according to the manufacturing method of the present embodiment, before the permanent magnet 12 is received in the magnet receiving hole 11, the permanent magnet 12 and the resin 13 are integrally molded, and the integrated resin 13 and permanent magnet 12 are inserted into the magnet receiving hole 11. For this reason, the resin 13 can be molded into an intended shape, and the resin 13 can be prevented from entering unintended regions.

[0046] Specifically, as shown in FIG. 6, the rotor core 10 is configured by laminating sheet members of electromagnetic steel sheets, and a slight gap can be formed between axially adjacent sheet members. If a configuration is adopted in which the resin 13 is filled into the magnet accommodation hole 11 that accommodates the permanent magnet 12, the uncured resin 13 will enter the gaps between the sheet members. When the resin 13 is cured in this case, the resin 13 exerts a force on the sheet members that separates the sheet members from each other. However, in the present embodiment, since the integrated resin 13 and permanent magnet 12 are inserted into the magnet accommodation hole 11, the resin 13 does not enter the gaps between the axially adjacent sheet members (electromagnetic steel sheets). Therefore, the resin 13 does not exert a force on the sheet members that separates the sheet members from each other.

[0047] Furthermore, in the present embodiment, the resin 13 can be molded outside the magnet accommodation hole 11, and a coolant flow path located inside the magnet accommodation hole 11 can be formed by this molding. Therefore, compared with a configuration in which the resin 13 is filled into the magnet accommodation hole 11 after the permanent magnet 12 is inserted into the magnet accommodation hole 11, a flow path having a desired shape can be easily formed.

[0048] Specifically, when the resin 13 is filled into the magnet accommodation hole 11 after the permanent magnet 12 is inserted into the magnet accommodation hole 11, it is impossible or difficult to fix the permanent magnet 12 accommodated in the magnet accommodation hole 11 without moving it. In addition, in a configuration in which resin is filled into the magnet accommodation hole with a rod-shaped mold inserted as in the prior art, it is impossible or difficult to fix the rod-shaped mold without moving it. Furthermore, when the resin 13 is filled into the magnet accommodation hole 11 after the permanent magnet 12 is inserted into the magnet accommodation hole 11, only an extremely simply shaped flow path can be formed, and it is impossible to form a flow path connected to the connecting coolant path 10a or a flow path with a complicated shape. However, in the present embodiment, since the resin 13 can be molded together with the permanent magnet 12 outside the magnet accommodation hole 11, a flow path having a desired shape can be easily formed.

[0049] Furthermore, according to this embodiment, when the magnet housing hole 11 is viewed along the axial direction, a resin 13 or space can be configured to exist between the permanent magnet 12 and the inner wall of the magnet housing hole 11. Therefore, there is no need to insulate the permanent magnet 12 from the inner wall of the magnet housing hole 11. As a result, the work process is simplified and costs are reduced compared to cases where insulation is required.

[0050] Next, the shaft 20 is attached to the rotor core 10 (step S125). Specifically, the shaft 20 to be attached to the rotor core 10 is prepared. As described above, the shaft 20 is a hollow cylindrical member and can be manufactured by various known methods. In addition, a radial refrigerant passage 20a is formed at a predetermined position on the shaft 20, extending radially and penetrating through it. That is, the radial refrigerant passage 20a is formed at a position where the connecting refrigerant passage 10a formed in the axial center of the rotor core 10 opens radially inward.

[0051] Once the shaft 20 having a radial refrigerant passage 20a is formed, the shaft 20 is fitted into a hole formed on the radially inner side of the rotor core 10, thereby attaching the shaft 20 to the rotor core 10. In the above configuration, when refrigerant is supplied to the cavity formed in the radial center of the shaft 20, the refrigerant can be supplied to region 14a, which is the region for the refrigerant, via the radial refrigerant passage 20a and the connecting refrigerant passage 10a. Since region 14a penetrates the rotor core 10 in the axial direction, the refrigerant that reaches region 14a flows from the axial center toward both ends.

[0052] As described above, the rotor core 10 according to this embodiment is equipped with a connecting refrigerant passage 10a in the axial center. Therefore, if resin 13 is filled into the magnet housing hole 11 in which a permanent magnet 12 is housed, the uncured resin 13 will enter the interior of the connecting refrigerant passage 10a. In this case, it is impossible or extremely difficult to remove the resin 13 that has entered the connecting refrigerant passage 10a. Consequently, if a method is used in which resin 13 is filled into the magnet housing hole 11 in which a permanent magnet 12 is housed, it becomes difficult to form the flow path, which is the region for the refrigerant, in the desired shape. However, in this embodiment, since the integrated resin 13 and permanent magnet 12 are inserted into the magnet housing hole 11, the resin 13 does not block the connecting refrigerant passage 10a, and it is possible to easily form the region for the refrigerant.

[0053] (3) Other Embodiments, etc.: The above embodiments are just examples for carrying out the present invention, and various other embodiments can be adopted. For example, in the rotor manufacturing method, the order of steps that can be changed may be changed. Specifically, the order of the magnet preparation step in step S100, the rotor core preparation step in step S105, and the mold preparation step in step S110 may be any order. Also, the step of preparing the shaft 20 may be performed before the shaft mounting step in step S125. Furthermore, in a configuration in which no protrusion 11a is formed in the magnet housing hole 11, the integrated resin 13 and permanent magnet 12 may be fixed in the magnet housing hole 11 with an adhesive or the like.

[0054] Furthermore, embodiments differing in at least part of the configuration of the above-described embodiments may be realized. For example, the flow path for supplying refrigerant to region 14a, which is the region for the refrigerant, is not limited to the connecting refrigerant path 10a. Specifically, the refrigerant may be supplied from the axial end of the rotor core 10. Alternatively, a refrigerant flow path may be formed radially outside the magnet housing hole 11, and the refrigerant may be supplied to region 14c through a hole extending from the flow path.

[0055] Furthermore, the refrigerant flow path may be formed by various methods, and the refrigerant flow path may be formed in the permanent magnet 12. The shape of the refrigerant flow path provided in the permanent magnet 12 may be of various shapes, but for example, the refrigerant flow path may be formed by a slit extending from the outer circumference of the permanent magnet 12 to the inside of the permanent magnet when viewed along the axial direction.

[0056] Figure 10 shows an example in which a slit 120a is formed in the permanent magnet 120. In the embodiment shown in Figure 10, the configuration other than the permanent magnet 120 is the same as in the embodiment described above. In this example, the slit 120a is the long side of the rectangle that forms the outer circumference when the permanent magnet 120 is viewed along the axial direction, extending from the long side that is in contact with region 14a in the direction along the short side, and is formed to penetrate the permanent magnet 120 in the axial direction. With this configuration, in addition to region 14a, the slit 120a can also be used as a coolant flow path. Therefore, the cooling efficiency can be further increased.

[0057] The size, shape, and number of slits 120a are not limited to the examples shown in Figure 10. For example, if region 14c also serves as a refrigerant flow path, slits extending from the longer side to the shorter side on the region 14c side may be formed. Alternatively, slits extending from the shorter side to the longer side may also be formed. Furthermore, if the refrigerant is supplied into the slits from the axial end, regions 14a, 14c, etc., do not necessarily have to be refrigerant flow paths.

[0058] Furthermore, the shape of the resin 13 is not limited to the shape of the embodiment described above, but can be of various shapes. For example, there may be a configuration in which at least one of the regions 14b, 14c, and 14d shown in Figure 4 does not exist, or the resin 13 may be in contact with the entire inner wall of the magnet housing hole 11, that is, with all four sides of the rectangle constituting the magnet housing hole 11. In the latter case, a region for refrigeration is formed between the resin 13 and the permanent magnet 12.

[0059] Furthermore, the permanent magnet 12 may be covered with resin. That is, the outer circumference of the permanent magnet 12 when viewed along the axial direction may be covered with resin. Figure 11 shows an example in which the outer circumference of the permanent magnet 12 is covered with resin 130. In the embodiment shown in Figure 11, the configuration other than the resin 130 is the same as in the embodiment described above. With this configuration, the permanent magnet 12 can be reliably insulated from the rotor core 10. The resin 130 shown in Figure 11 may be molded by various methods, for example, it can be formed by molding with the mold 30 shown in Figure 9A and then molding the remaining resin 130 with another mold.

[0060] Furthermore, the resin may be present in only a portion of the axial direction. For example, the resin may be present in a portion of the region formed between the permanent magnet and the inner wall of the magnet housing hole in a first portion which is a portion of the axial direction. In this case, the amount of resin present in the second portion which is different from the first portion in the axial direction is less than the amount of resin present in the first portion.

[0061] Figure 12 shows an example of such a configuration. In Figure 12, the same reference numerals are used to indicate components similar to those in the above-described embodiment. Furthermore, the shapes of the rotor core, permanent magnets, and magnet housing holes when viewed along the axial direction are the same as those shown in Figure 3, and Figure 12 is a cross-sectional view showing the rotor core 10 cut along the line C-C shown in Figure 3.

[0062] In the example shown in Figure 12, resin 130 is present in the first portion Z1, which is part of the axial direction, but not in the second portion Z2, which is not part of the first portion Z1. Therefore, the amount of resin present in the second portion is less than the amount of resin present in the first portion.

[0063] In the example shown in Figure 12, one out of every seven sheet members has a protrusion 11a formed on it, while the remaining six sheet members do not have a protrusion 11a. This configuration results in the protrusions 11a being discretely distributed in the axial direction. The protrusions 11a are formed at positions corresponding to the resin 130 present in the first portion Z1. That is, when the permanent magnet 12 and the resin 130 are inserted into the magnet housing hole 11 in an integrated state, the protrusions 11a elastically deform in the axial direction, as shown in Figure 12, and in this elastically deformed state, the protrusions 11a exist between the inner wall 11b and the resin 130. Therefore, an elastic force acts from the protrusions 11a on the resin 130, holding the integrated resin 130 and permanent magnet 12 housed in the magnet housing hole 11. With this configuration, the integrated resin 130 and permanent magnet 12 can be held within the magnet housing hole 11 without the use of adhesive.

[0064] Furthermore, there are various methods for integrating the resin 130 present in the first portion Z1, which is discretely present in the axial direction, with the permanent magnet 12. For example, a configuration may be adopted in which, in the axial direction of a mold as shown in Figure 9A, portions with and without cavities 31 are formed, and the resin 130 present in the first portion Z1 is formed by filling each cavity 31 with resin. Alternatively, after the resin is formed using a mold similar to that in Figure 9A, the resin present in the second portion may be removed, so that there is no resin 130 in the second portion Z2 and there is resin 130 in the first portion Z1.

[0065] As described above, with the configuration in which resin 130 is present in the first portion Z1 in the axial direction and not in the second portion Z2, the volume of the space that serves as the flow path for the refrigerant can be increased compared to a configuration in which resin is present throughout the entire axial direction. Therefore, the refrigerant can be made to flow more easily, and the cooling efficiency when cooling the permanent magnet 12 can be improved.

[0066] Furthermore, the configuration is not limited to one in which the second portion exists discretely. Figure 13 shows a configuration in which the first portion Z1 is present at both ends of the rotor core in the axial direction, and the region between the first portion Z1 present at both ends in the axial direction is the second portion Z2. In Figure 13, the same reference numerals are used to indicate the same configuration as in the above-described embodiment. Also, the shapes of the rotor core, permanent magnets, and magnet housing holes when viewed along the axial direction are the same as those shown in Figure 3, and Figure 13 is a cross-sectional view showing the rotor core 10 cut along the line C-C shown in Figure 3.

[0067] In the example shown in Figure 13, resin 131 is formed in the first portion Z1 located at both ends in the axial direction, and the area between the first portion Z1 is the second portion Z2, where resin 131 is absent. Therefore, the amount of resin present in the second portion is less than the amount of resin present in the first portion.

[0068] In the example shown in Figure 13, there is a sheet member with protrusions 11a formed at both ends in the axial direction, while the remaining sheet member does not have protrusions 11a. With this configuration, the protrusions 11a are formed at positions corresponding to the resin 131 present in the first portion Z1. That is, when the permanent magnet 12 and the resin 131 are inserted into the magnet housing hole 11 in an integrated state, the protrusions 11a elastically deform in the axial direction as shown in Figure 13, and in this elastically deformed state, the protrusions 11a are positioned between the inner wall 11b and the resin 131. As a result, an elastic force acts from the protrusions 11a to the resin 131, and the integrated resin 131 and permanent magnet 12 are held in place within the magnet housing hole 11. With this configuration, the integrated resin 131 and permanent magnet 12 can be held within the magnet housing hole 11 without the use of adhesive.

[0069] Furthermore, there may be various methods for integrating the resin 131 present in the first portion Z1, which is discretely present in the axial direction, with the permanent magnet 12. For example, a configuration may be adopted in which portions with cavities 31, as shown in Figure 9A, are formed at both ends in the axial direction, and the resin 131 is formed in the first portion Z1 present at both ends in the axial direction by the cavities 31. Alternatively, after the resin is formed by a mold similar to that in Figure 9A, the resin may be removed from portions other than both ends, so that the second portion Z2 does not have resin 131, and the resin 131 present in the first portion Z1 is formed.

[0070] As described above, the configuration in which resin 131 is present in the first portion Z1 in the axial direction and not in the second portion Z2 allows for an increase in the volume of the space that serves as the coolant flow path compared to a configuration in which resin is present throughout the entire axial direction. Therefore, the coolant can flow more easily, and the cooling efficiency when cooling the permanent magnet 12 can be improved. In addition, in the second portion Z2, it is sufficient that there is less resin than in the first portion Z1, and the configuration is not limited to one in which resin is not present throughout the entire axial direction of the second portion Z2, as shown in Figures 12 and 13. That is, a configuration in which resin is present in a part of the second portion Z2, but not in the remaining part of the second portion Z2 may be adopted.

[0071] The magnet preparation step only requires the preparation of multiple permanent magnets. The permanent magnets can be housed in multiple magnet housing holes to form magnetic poles. That is, one or more permanent magnets can be housed in each magnet housing hole to form one magnetic pole. The total number of magnetic poles formed in the rotor core can be two or more, and is not limited to a specific number of poles. Furthermore, the permanent magnets can be of a size and shape such that, when housed in the magnet housing holes, areas for resin and coolant are formed on the inner side of the inner wall of the magnet housing holes, and are not limited to the size and shape of the embodiments described above.

[0072] The rotor core preparation step only requires the preparation of an annular rotor core having multiple magnet housing holes that penetrate axially and accommodate at least one of a plurality of permanent magnets. The rotor core only needs to be a rotating body that rotates as the magnetic poles formed by the magnets housed in the magnet housing holes interact with the magnetic field formed by the stator. The magnet housing holes only need to penetrate axially so that an integrated permanent magnet and resin can be inserted and so that they can form a region for a coolant.

[0073] The number, orientation, and size of the magnet housing holes are not limited. In other words, the magnet housing holes only need to be configured such that the magnetic poles of the rotor core are formed when magnets are housed in them. The number of permanent magnets housed in the magnet housing holes only needs to be one or more. In other words, one permanent magnet may be housed in one magnet housing hole, or two or more permanent magnets may be housed in one magnet housing hole.

[0074] The magnetic poles may be formed by a single permanent magnet or by multiple permanent magnets. Furthermore, although the rotor core is annular, the shape of the inner circumferential surface on the radially inner side and the outer circumferential surface on the radially outer side are not limited to a circular shape. For example, the radially inner surface may have a polygonal shape or other shapes. Of course, the shape in the axial direction is also not limited, and structures for attaching various components may be formed. Moreover, it is preferable that the rotor core be made of a material through which the magnetic flux generated by the magnets formed in the magnet housing holes passes efficiently. For this reason, it is preferable that the rotor core be constructed by laminating electromagnetic steel sheets made of a magnetic material.

[0075] The molding step only needs to be able to mold the resin so that it integrates with each of the multiple permanent magnets. In other words, the molding step only needs to be able to mold the resin so that it integrates with the permanent magnets.

[0076] During molding, with the integrated permanent magnet and resin inserted into the magnet housing hole, the shape of the resin is adjusted so that a region for the refrigerant is formed on the inner side of the inner wall of the magnet housing hole. In other words, when the magnet housing hole is viewed along the axial direction, it is sufficient to mold the resin such that a portion of the region formed between the permanent magnet and the inner wall of the magnet housing hole is resin, and at least a portion of the remaining region is for the refrigerant. When the magnet housing hole is viewed along the axial direction, the remaining region, excluding the region where the resin and the region where the permanent magnet are located, should at least be a portion of the region for the refrigerant. Therefore, the entire remaining region may be for the refrigerant, or a portion of the region may be for purposes other than the refrigerant.

[0077] The resin only needs to be present in a portion of the region formed between the permanent magnet and the inner wall of the magnet housing hole, and its cross-sectional shape in the direction perpendicular to the axial direction may be the same throughout the entire axial region or may differ depending on the axial position. The region for the refrigerant only needs to be present in at least a portion of the region where the permanent magnet and resin are not present when the magnet housing hole is viewed from the axial direction. Therefore, the region for the refrigerant may be present in the entire region where the permanent magnet and resin are not present or in only a portion of it. The region for the refrigerant may be a cavity that penetrates in the axial direction or may not penetrate. In the former case, the cross-sectional shape of the region for the refrigerant in the direction perpendicular to the axial direction may be the same throughout the entire axial region or may differ depending on the axial position.

[0078] The refrigerant can be any medium capable of dissipating heat from the rotor core and permanent magnets, and is not limited to liquids; it can also be a gas. Furthermore, the refrigerant may or may not flow within the region designated for the refrigerant. In the former case, the region designated for the refrigerant becomes the flow path for the refrigerant.

[0079] The insertion step only needs to involve inserting the integrated resin and permanent magnet into the magnet housing holes. That is, the resin and permanent magnet to be inserted into each of the magnet housing holes should be molded in the molding step, and the molded integrated resin and permanent magnet should be able to be inserted into each of the magnet housing holes.

[0080] The protrusions only need to be portions that protrude from the inner wall of the magnet housing hole toward the resin and exist discretely in the axial direction. In other words, the protrusions only need to be able to hold the permanent magnet in the magnet housing hole by elastic deformation between the inner wall and the resin. To this extent, the number, size, and shape of the protrusions are not limited. Furthermore, the protrusions only need to be able to hold the permanent magnet, which is integrated with the resin, in the magnet housing hole. Therefore, it is sufficient that they protrude from the inner wall of the magnet housing hole toward at least some of the resin. For example, in a configuration where there is resin at multiple positions between the inner wall of the magnet housing hole and the permanent magnet when viewed from the axial direction, the protrusions may protrude toward the resin at all positions, or they may protrude toward the resin at some positions.

[0081] 1...Rotor, 10...Rotor core, 10a...Connecting refrigerant passage, 11...Magnet housing hole, 11a...Protrusion, 11b...Inner wall, 12...Permanent magnet, 12a...Slit, 13...Resin, 14a...Region, 14b...Region, 14c...Region, 14d...Region, 20...Shaft, 20a...Radial refrigerant passage, 30...Mold, 31...Cavity, 31a...Protrusion, 31b...Protrusion, 31c...Protrusion, 31d...Protrusion,

Claims

1. A method for manufacturing a rotor, comprising: a magnet preparation step of preparing a plurality of permanent magnets; a rotor core preparation step of preparing an annular rotor core having a plurality of magnet housing holes that penetrate in the axial direction and accommodate at least one of the plurality of permanent magnets; a molding step of molding to integrate a resin with each of the plurality of permanent magnets; and an insertion step of inserting the integrated resin and each of the permanent magnets into the magnet housing holes, wherein the molding step includes molding the resin such that, when the magnet housing holes are viewed along the axial direction, the resin is present in a portion of the region formed between the permanent magnets and the inner wall of the magnet housing holes, and at least a portion of the remaining portion of the region is present for a coolant.

2. The method for manufacturing a rotor according to claim 1, wherein the molding step includes molding the resin such that, when the magnet housing hole is viewed along the axial direction, the resin or space exists between the permanent magnet and the inner wall of the magnet housing hole.

3. The method for manufacturing a rotor according to claim 1 or 2, wherein the rotor core preparation step includes forming protrusions that project from the inner wall of the magnet housing hole toward the resin and are discretely present in the axial direction.

4. The method for manufacturing a rotor according to claim 1 or 2, wherein the magnet preparation step includes forming a slit extending from the outer circumference of the permanent magnet to the inside of the permanent magnet when viewed along the axial direction.

5. The method for manufacturing a rotor according to claim 1 or 2, wherein the molding step includes a step of covering the outer circumference of the permanent magnet with the resin when viewed along the axial direction.

6. A method for manufacturing a rotor according to claim 1 or 2, further comprising a shaft mounting step of preparing a hollow shaft and attaching it to the radial center of the rotor core, the shaft mounting step comprising forming a radial refrigerant passage in the shaft, which is a hole extending radially and connected to the hollow portion of the shaft, and the rotor core preparation step comprising forming a connecting refrigerant passage in the rotor core, which is a hole connecting the radial refrigerant passage to the area for refrigerant formed in the magnet housing hole.

7. A rotor comprising: a plurality of permanent magnets; an annular rotor core having a plurality of magnet housing holes that penetrate in the axial direction and accommodate at least one of the plurality of permanent magnets; and a resin that, when the magnet housing holes are viewed along the axial direction, is present in a portion of the region formed between the permanent magnets and the inner walls of the magnet housing holes, thereby forming the region for refrigeration in at least a portion of the remaining portion of the region, wherein the rotor core is composed of a plurality of laminated electromagnetic steel sheets, and the resin does not penetrate into the gaps between the electromagnetic steel sheets in the axial direction.

8. The rotor according to claim 7, further comprising projections that protrude from the inner wall of the magnet housing hole toward the resin and are discretely located in the axial direction, wherein the projections hold the permanent magnet in the magnet housing hole by elastic deformation between the inner wall and the resin.

9. The rotor according to claim 7 or 8, wherein the resin is present in a portion of the region formed between the permanent magnet and the inner wall of the magnet housing hole in a first portion which is a part in the axial direction, and the amount of the resin present in a second portion which is different from the first portion in the axial direction is less than the amount of the resin present in the first portion.

10. The rotor according to claim 9, wherein the first portion is located at both axial ends of the rotor core, and the region between the first portions located at both axial ends is the second portion.

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