Method for producing rotor and rotor

Abstract

The present invention provides a method which is for producing a rotor and which makes it possible to stably attach an annular member to the outer periphery of a rotor core. Provided is a method for producing a rotor, wherein: a columnar rotor core 3 is disposed inside an annular member 5; an end portion 5a of the annular member 5 is caused to protrude from an end portion 3a of the rotor core 3 in the axial direction; an end plate 7 having a thermal expansion coefficient higher than that of the annular member 5 is disposed inside the end portion 5a of the annular member 5; the gap between the end plate 7 and the annular member 5 is sealed in accordance with the difference in thermal expansion between the annular member 5 and the end plate 7; a flow path 7e which is for a resin 15 and which extends to an injection space between the annular member 5 and the rotor core 3 is defined; the resin 15 is injected into the injection space 13 through the defined flow path 7e, and cured; and the end plate 7 is left inside the end portion 5a of the annular member 5.

Description

Rotor manufacturing method and rotor

[0001] The present invention relates to a rotor manufacturing method for a rotor in which an annular member is attached to a columnar rotor core, and to a rotor.

[0002] As a conventional rotor, for example, there is a rotor in which an annular member is attached to the outer periphery of a columnar rotor core, as disclosed in Patent Document 1.

[0003] Attachment of the annular member to the rotor core is preferably performed by interference fitting such as press fitting or shrink fitting in order to ensure strength. However, depending on the material of the annular member, it hardly undergoes thermal expansion or there is a limit to the interference amount, so the annular member could not be stably attached to the rotor core.

[0004] Japanese Patent No. 6220328

[0005] The problem to be solved is that the annular member cannot be stably attached to the rotor core.

[0006] The present invention provides a rotor manufacturing method comprising: arranging a columnar rotor core inside an annular member; causing an end portion of the annular member to protrude from an end portion of the rotor core in an axial direction; arranging an end plate having a higher coefficient of thermal expansion than the annular member in the end portion of the annular member; sealing a gap between the end plate and the annular member according to a difference in thermal expansion between the annular member and the end plate, and defining a resin flow path leading to an injection space between the annular member and the rotor core; injecting the resin into the injection space through the defined flow path and curing the resin, and leaving the end plate at the end portion of the annular member.

[0007] Furthermore, the present invention provides a rotor comprising: a columnar rotor core; an annular member having an interior in which the rotor core is arranged and an end projecting axially from the end of the rotor core; an end plate disposed within the end of the annular member and having a higher coefficient of thermal expansion than the annular member; a flow path partitioned between the end plate and the rotor core and leading to an injection space between the annular member and the rotor core; an injection port of the flow path that penetrates the end plate; and a resin cured across the injection port, the flow path, and the injection space.

[0008] According to the present invention, an annular member can be stably attached to the outer circumference of the rotor core using resin.

[0009] Figure 1 is a perspective view showing a rotor according to Embodiment 1 of the present invention. Figure 2 is a perspective view of the rotor core used in the rotor of Figure 1. Figure 3 is a cross-sectional view taken along line III-III of Figure 1. Figure 4 is a schematic perspective view showing a manufacturing apparatus for the rotor of Figure 1. Figure 5 is a cross-sectional view taken along line V-V of Figure 4. Figure 6 is a cross-sectional view showing the rotor core of the rotor of Figure 1 placed inside an annular member. Figure 7 is an enlarged cross-sectional view showing the ends of the rotor core and the annular member of Figure 6. Figure 8 is a cross-sectional view showing a rotor in a temporary assembly state with end plates fitted to both ends of the annular member. Figure 9 is a cross-sectional view showing the rotor in the temporary assembly state of Figure 8 placed on a lower mold. Figure 10 is a cross-sectional view showing a manufacturing apparatus with an upper mold placed on the rotor in the temporary assembly state of Figure 9. Figure 11 is an enlarged cross-sectional view showing a part of the manufacturing apparatus of Figure 10. Figure 12 is an enlarged cross-sectional view showing a part of the manufacturing apparatus of Figure 10 during resin injection. Figure 13 is a cross-sectional view showing a part of the manufacturing apparatus for a rotor according to Embodiment 2 of the present invention. Figure 14 is a cross-sectional view showing a part of the rotor manufacturing apparatus according to Embodiment 3 of the present invention. Figure 15 is a cross-sectional view showing a part of the rotor manufacturing apparatus according to a modified example of Embodiment 3. Figure 16 is a cross-sectional view showing a part of the rotor manufacturing apparatus according to another modified example of Embodiment 3.

[0010] In one embodiment of the rotor 1 manufacturing method, a columnar rotor core 3 is placed inside an annular member 5, the end 5a of the annular member 5 protrudes axially from the end 3a of the rotor core 3, and an end plate 7 with a higher coefficient of thermal expansion than the annular member 5 is placed inside the end 5a of the annular member 5. Then, according to the difference in thermal expansion between the annular member 5 and the end plate 7, the space between the end plate 7 and the annular member 5 is sealed, and the flow path 7e of the resin 15 leading to the injection space 13 between the annular member 5 and the rotor core 3 is partitioned. The resin 15 is injected into the injection space 13 from the partitioned flow path 7e and cured, leaving the end plate 7 on the end 5a of the annular member 5.

[0011] In the sealing method using the difference in thermal expansion between the end plate 7 and the annular member 5, in one embodiment, the end plate 7 is fitted into the end portion 5a of the annular member 5 and then heated together with the annular member 5. As a result, the end plate 7 is tightly fitted into the end portion 5a of the annular member 5 due to the difference in thermal expansion, and the space between the end plate 7 and the annular member 5 is sealed.

[0012] The end plate 7 can be positioned within the end 5a of the annular member 5 on one or both sides in the axial direction. When the end plate 7 is positioned within the end 5a of the annular member 5 on both sides in the axial direction, the space between the end plate 7 and the annular member 5 is sealed on both sides in the axial direction, and the partitioning of the flow path 7e is performed on one side in the axial direction.

[0013] In one embodiment, the end plate 7 may expand the diameter of the end 5a of the annular member 5 in accordance with the difference in thermal expansion relative to the annular member 5, thereby expanding the injection space 13 at the end 3a of the rotor core 3.

[0014] In this case, it is preferable to inject the resin 15 to expand the diameter of the annular member 5 between its ends 5a relative to the rotor core 3, and to cure the resin 15 while expanding the diameter of the annular member 5.

[0015] The end plate 7 has an injection port 7d for the resin 15 into the flow path 7e. Preferably, the injection port 7d has guide surfaces 7da and 7db that are directed toward the injection space 13.

[0016] In one embodiment, the injection port 7d may be a hole inclined axially toward the injection space 13, and the guide surface 7da may be the inner surface of the hole.

[0017] In another embodiment, the end plate 7 may be composed of a first plate portion 25a and a second plate portion 25b, and an injection port 7d and a guide surface 7db may be provided on the first plate portion 25a and the second plate portion 25b, respectively.

[0018] In this case, the first plate portion 25a is located proximal to the rotor core 3 in the axial direction, and the second plate portion 25b is located distal to the rotor core 3 in the axial direction. The injection port 7d penetrates the second plate portion 25b, and the guide surface 7db is provided on the first plate portion 25a facing the injection port 7d in the axial direction. This guide surface 7db is a slope that gradually widens the axial gap between the injection port 7d and the first plate portion 25a toward the injection space 13.

[0019] The end plate 7 may partition the vent 7f that extends outside the flow path 7e.

[0020] The manufactured rotor 1 comprises a rotor core 3, an annular member 5, an end plate 7, a flow path 7e, an injection port 7d, and resin 15. In this rotor 1, the resin 15 is cured across the injection port 7d, the flow path 7e, and the injection space 13.

[0021] [Rotor Structure] Figure 1 is a perspective view showing a rotor according to Embodiment 1 of the present invention. Figure 2 is a perspective view of the rotor core used in the rotor of Figure 1. Figure 3 is a cross-sectional view taken along line III-III of Figure 1.

[0022] The rotor 1, together with the stator, constitutes a rotating electric machine. The rotor 1 in this embodiment comprises a rotor core 3, an annular member 5, and an end plate 7. This rotor 1 is an SPM (Surface Permanent Magnet) rotor in which magnets 11 are arranged on the outer circumferential surface of the rotor core 3. Alternatively, the rotor 1 may be an IPM (Internal Permanent Magnet) rotor in which magnets are housed in magnet housing holes in the rotor core 3.

[0023] The rotor core 3 comprises an iron core 9 and magnets 11. The iron core 9 consists of a single columnar body. However, the iron core 9 may also be a laminate formed by stacking multiple flat core pieces. The planar shape of the iron core 9 is circular, and a circular central hole 9a is provided in the center. However, the planar shape of the iron core 9 may also be a polygon or a combination of arcs and straight sections. The central hole 9a penetrates the iron core 9 in the axial direction. The axial direction is along the axis of the rotor 1. Magnets 11 are arranged on the outer circumference of this iron core 9.

[0024] The magnet 11 can be made of a permanent magnet (including one that has not yet been magnetized), such as a ferrite-based sintered magnet piece or a neodymium magnet piece. In this embodiment, multiple magnets 11, for example four, are arranged along the outer circumference of the iron core 9. Each magnet 11 is a plate-like body that is curved in an arc along the outer circumference of the iron core 9. The multiple magnets 11 are arranged in contact with each other in the circumferential direction, forming an annular shape that covers the outer circumference of the iron core 9 as a whole. The circumferential direction is the direction along the outer circumference of the rotor 1.

[0025] These multiple annular magnets 11 constitute the radial surface of the rotor core 3. For this reason, the rotor core 3 is cylindrical. However, the rotor core 3 does not need to be cylindrical. It is sufficient that the rotor 1, to which the annular member 5 is attached, is cylindrical. The radial direction is the direction along the diameter of the rotor 1.

[0026] The shape and arrangement of the magnets 11 can be arbitrarily set. For example, the magnets 11 may be arranged with gaps in the circumferential direction. In this case, radial recesses for holding the magnets 11 may be provided in the iron core 9. Furthermore, the shape of the magnets 11 can be any appropriate shape, such as a semicircular cross-section.

[0027] The annular member 5 functions as a reinforcing member for the rotor core 3. The annular member 5 is cylindrical and has openings on both sides in the axial direction. The radial thickness of the annular member 5 is, for example, 0.2 mm to 2 mm. The material of the annular member 5 can be set as appropriate, but can be, for example, a metal such as titanium or a resin such as fiber-reinforced plastic.

[0028] This annular member 5 is attached to the outer circumference of the rotor core 3. In the axial direction, the annular member 5 is larger in dimension than the rotor core 3, and its end 5a protrudes from the end 3a of the rotor core 3. Therefore, the annular member 5 has an interior in which the rotor core 3 is positioned, and has an end 5a that protrudes in the axial direction relative to the end 3a of the rotor core 3.

[0029] The annular member 5 is attached to the rotor core 3 by the curing of resin 15 injected into the injection space 13, which is the radial gap between the annular member 5 and the rotor core 3.

[0030] The end plate 7 is a plate-like body positioned within the end portion 5a of the annular member 5. This end plate 7 is attached to the rotor 1 for purposes such as balance adjustment.

[0031] In this embodiment, the end plate 7 is configured in a disc shape, with its outer circumferential surface fitted to the inner circumferential surface of the end portion 5a. A communication hole 7a is provided in the center of the end plate 7, which communicates with the central hole 9a of the rotor core 3.

[0032] The end plate 7 is a component with a higher coefficient of thermal expansion than the annular member 5. In this embodiment, the end plate 7 is formed from, for example, an iron-based material. However, the material of the end plate 7 is not limited to a specific material, as long as its coefficient of thermal expansion is higher than that of the annular member 5.

[0033] The outer surface 7b of the end plate 7 is flush with the axial edge of the annular member 5. However, the surface 7b may be positioned to protrude or recede in the axial direction relative to the axial edge of the annular member 5.

[0034] The end plate 7 has a back surface 7c located on the opposite side in the axial direction from the front surface 7b, which abuts against the axial end surface 3b of the rotor core 3. On the back surface 7b of one (upper) end plate 7, a groove-shaped flow path 7e is provided, extending from the injection port 7d to the radial outer circumference. Therefore, the flow path 7e is partitioned by the end plate 7 and leads from the injection port 7d to the injection space 13.

[0035] In this embodiment, the flow path 7e has a closed cross-section between the end plate 7 and the rotor core 3, and faces the injection space 13 between the annular member 5 and the rotor core 3. The flow path 7e then causes the uncured resin 15 injected from the injection port 7d to flow into the injection space 13.

[0036] The injection port 7d is provided, penetrating the end plate 7 in the axial direction. In this embodiment, the injection port 7d has a rectangular opening. Multiple injection ports 7d are provided at intervals in the circumferential direction, for example, four of them. The shape and number of injection ports 7d can be arbitrarily set.

[0037] The resin 15 hardens from this injection port 7d through the flow path 7e and the injection space 13.

[0038] The resin 15 hardens in a state where the annular member 5 is expanded in diameter compared to its natural state before resin injection. As a result, a restoring force acts on the annular member 5, causing it to return to its non-expanded state, and the annular member 5 is attached to the rotor core 3 by the hardened resin 15 through an interference fit. This allows the magnet 11 to be firmly fixed.

[0039] Furthermore, the resin 15 has one end plate 7 attached to one or both of the rotor core 3 and the annular member 5 at the portion located in the flow path 7e and the injection port 7d. The resin 15 is bent in a crank shape at the injection port 7d, the flow path 7e, and the injection space 13, improving the strength of the attachment of one end plate 7.

[0040] [Rotor Manufacturing Apparatus] Figure 4 is a schematic perspective view showing the rotor manufacturing apparatus of Figure 1. Figure 5 is a cross-sectional view taken along line V-V in Figure 4.

[0041] The rotor 1 manufacturing apparatus 17 comprises an upper mold 19, a lower mold 21, and a resin injection machine 23, as shown in Figures 4 and 5. The resin injection machine 23 is shown conceptually only by a dashed line in Figure 5.

[0042] The upper die 19 and the lower die 21 press the rotor core 3 arranged inside the annular member 5 from above and below. For this reason, the upper die 19 and the lower die 21 are formed in a disc shape having an outer diameter smaller than the inner diameter of the annular member 5. Accordingly, the upper die 19 and the lower die 21 are configured not to restrain the annular member 5 in the radial direction during pressing. The interior of the annular member 5 in the present embodiment is an internal space defined by the inner circumference of the annular member 5. Note that "upper" and "lower" herein refer to the upper side and the lower side respectively when the axial direction of the rotor 1 is aligned with the vertical direction.

[0043] The rotor 1 is placed on the lower die 21. A shaft 21a is projectingly provided on the lower die 21. The shaft 21a extends along the axial direction of the rotor 1 placed on the lower die 21, and fits into the central hole 9a of the rotor core 3. The upper end of the shaft 21a projects upward from the central hole 9a of the rotor core 3 and reaches the inside of the communication hole 7a of the end plate 7. Note that the upper die 19 may be provided with a relief portion, and the shaft may be configured to position the rotor by penetrating through two end plates and the rotor core 3.

[0044] The upper die 19 is supported so as to be movable up and down relative to the lower die 21, enabling pressurization of the end plate 7. The vertical movement of the upper die 19 may be performed by an appropriate driving device such as a linear actuator.

[0045] The upper die 19 is provided with a discharge port 19a for the resin 15. The discharge port 19a vertically penetrates the upper die 19 and communicates with the injection port 7d of the end plate 7 of the rotor 1. The cross-sectional shape of the discharge port 19a gradually decreases toward the injection port 7d.

[0046] The upper die 19 and the lower die 21 are used after being heated to the resin molding temperature. By this heating, the upper die 19 and the lower die 21 heat the rotor 1 held therebetween. Note that the heating of the upper die 19 and the lower die 21 may be performed in advance before sandwiching the rotor 1, or may be performed in the state where the rotor 1 is sandwiched therebetween. The rotor core 3 and the end plates 7 may be heated to the resin molding temperature before being sandwiched between the upper die 19 and the lower die 21, or may be heated to the resin molding temperature using a heating mechanism of the upper die 19 and the lower die 21.

[0047] The resin injector 23 injects resin into the rotor 1 from the discharge port 19a. The resin injector 23 can be configured by a well-known injection unit or the like.

[0048] The resin injector 23 presses the annular member 5 radially outward against the rotor core 3 by injecting the resin 15. As described later, the pressing in the present embodiment is performed to such an extent that the entire injection space 13 expands in diameter between the annular member 5 and the rotor core 3 in accordance with the injection space 13 expanded at the end portion 3a of the rotor core 3.

[0049] [Method for Manufacturing Rotor] FIG. 6 is a cross-sectional view showing a state where the rotor core of the rotor in FIG. 1 is arranged inside the annular member. FIG. 7 is an enlarged cross-sectional view showing an end portion of the rotor core and an end portion of the annular member in FIG. 6.

[0050] In the method for manufacturing the rotor 1 according to the present embodiment, as shown in FIG. 6, a columnar rotor core 3 is first arranged inside the annular member 5.

[0051] That is, in the separated state of the annular member 5 and the rotor core 3, the inner circumference of the annular member 5 is aligned with the outer circumference of the rotor core 3, and they are moved so as to slide relatively to each other. Accordingly, the rotor core 3 is inserted into and arranged inside the annular member 5. The arrangement of the rotor core 3 in the annular member 5 is performed such that the end portions 5a of the annular member 5 protrude axially relative to the end portions 3a of the rotor core 3 on both axial sides.

[0052] At this time, as shown in FIG. 7, the inner diameter of the annular member 5 is larger than the outer diameter of the rotor core 3, that is, there is a radial injection space (clearance) 13 between the inner circumference of the annular member 5 and the outer circumference of the rotor core 3. The injection space 13 is set to, for example, 0.1 mm to 0.3 mm.

[0053] Therefore, the attachment of the annular member 5 to the rotor core 3 is achieved by clearance fitting. Accordingly, the rotor core 3 can be smoothly inserted into the annular member 5, and scratches or the like on the inner circumference of the annular member 5 are suppressed.

[0054] FIG. 8 is a cross-sectional view showing a temporarily assembled rotor in which end plates are clearance-fitted to both end portions of the annular member.

[0055] After the rotor core 3 is placed inside the annular member 5, the end plates 7 are placed inside the ends 5a of the annular member 5 on both sides in the axial direction. At this time, the inner diameter of the annular member 5 is larger than the outer diameter of the end plates 7. Therefore, the end plates 7 are fitted into the end 5a of the annular member 5. Consequently, the end plates 7 can be smoothly attached to the end 5a of the annular member 5, and scratches on the inner circumference of the annular member 5 are suppressed.

[0056] By positioning the end plate 7 within the end portion 5a of the annular member 5, the rotor 1 is put into a temporary assembly state. Subsequently, the temporarily assembled rotor 1 is placed between the upper mold 19 and the lower mold 21 as shown in Figures 4 and 5.

[0057] Figure 9 is a cross-sectional view showing the rotor in the pre-assembled state from Figure 8 placed on the lower mold. Figure 10 is a cross-sectional view showing the upper mold placed on the rotor in the pre-assembled state from Figure 9. Figure 11 is an enlarged cross-sectional view showing a part of the manufacturing apparatus from Figure 10. Figure 12 is an enlarged cross-sectional view showing a part of the manufacturing apparatus from Figure 10 during resin injection.

[0058] When positioning the rotor 1 between the upper mold 19 and the lower mold 21, the upper mold 19 is raised in advance, as shown in Figure 9. Then, the rotor 1 in a partially assembled state is placed on the lower mold 21. At this time, the upper surface of the lower mold 21 is brought into contact with the surface of the other (lower) end plate 7 of the rotor 1.

[0059] In this state, the shaft 21a passes through the communication hole 7a of the end plate 7 on one axial side, enters the communication hole 7a of the end plate 7 on the other axial side, and also passes through the central hole 9a of the rotor core 3. Therefore, concentricity between the end plate 7 and the rotor core 3 can be ensured.

[0060] Next, as shown in Figure 10, the upper mold 19 is lowered so that its lower surface contacts the surface 7b of one (upper) end plate 7. In this state, the rotor 1 in the temporary assembly state is heated while the upper mold 19 and lower mold 21 pressurize the space between the end plates 7. As a result, the end plates 7 are heated together with the annular member 5 on both sides in the axial direction, and due to the difference in thermal expansion, they are tightly fitted into the end portion 5a of the annular member 5.

[0061] In other words, the heated end plate 7 expands in diameter relative to the annular member 5 in accordance with the difference in thermal expansion. Due to this expansion, the outer circumferential surface of the end plate 7 comes into radial contact with the inner circumferential surface of the end portion 5a of the annular member 5.

[0062] As a result, the end plate 7 is tightly fitted into the end portion 5a of the annular member 5. Therefore, in the temporarily assembled state, the rotor 1 is sealed between the end plate 7 and the annular member 5 on both sides in the axial direction. Through this seal, on one side (upper) in the axial direction, the end plate 7 demarcates the flow path 7e of the resin 15 leading to the injection space 13 between the annular member 5 and the rotor core 3.

[0063] In this embodiment, as shown in Figure 11, the diameter of the end plate 7 is expanded to expand the end 5a of the annular member 5. At this time, since the end 5a of the annular member 5 is not constrained by the upper mold 19, the expansion is performed easily and smoothly. Through this expansion, the restoring force of the annular member 5 ensures a secure seal between the end plate 7 and the annular member 5. The amount of expansion of the end 5a of the annular member 5 at this time is, for example, several tens of micrometers to several hundred micrometers. In addition, the expansion of the end 5a of the annular member 5 expands the injection space 13 at the axial end 3a of the rotor core 3.

[0064] Subsequently, as shown in Figures 5 and 12, the resin 15 is injected into the injection space 13 from the partitioned flow path 7e and cured, leaving the end plate 7 on the end 5a of the annular member 5. Specifically, the resin 15 is discharged from the discharge port 19a of the upper mold 19 by the resin injection machine 23. The discharged resin 15 reaches the injection space 13 through the flow path 7e from the injection port 7d of the end plate 7.

[0065] At this time, the end plate 7 and the end portion 5a of the annular member 5 are in contact radially, which improves sealing performance and allows the resin 15 to be reliably injected into the injection space 13 while suppressing leakage of the resin 15. In addition, because the injection space 13 is expanded in the portion into which the resin 15 flows, the resin 15 can be reliably injected into the injection space 13 before it hardens.

[0066] The resin 15 injected into the injection space 13 presses the annular member 5 radially outward relative to the rotor core 3. This pressing causes the annular member 5 to elastically deform radially outward as a whole, not just at both ends 5a, as shown in Figure 12. Therefore, in this embodiment, the annular member 5 expands in diameter between its ends 5a in proportion to the expansion of the annular member 5a at both ends 5a.

[0067] Then, the resin 15 is cured while the annular member 5 expands in diameter. Preferably, the expanded diameter of the annular member 5 at this time is the same as when the resin 15 was injected, but it may be larger or smaller than when the resin 15 was injected. In other words, the annular member 5 at the time of curing of the resin 15 should be in a state that has expanded in diameter compared to before the resin 15 was injected.

[0068] Once the resin 15 hardens, the annular member 5 is attached to the rotor core 3. In this state, the hardened resin 15 maintains the expanded diameter of the annular member 5 relative to the rotor core 3. In other words, a restoring force acts on the annular member 5 to return it to its non-expanded state, causing the annular member 5 to be tightly fitted onto the rotor core 3 via the hardened resin 15.

[0069] Furthermore, the cured resin 15 is located within the discharge port 19a of the upper mold 19, the injection port 7d of one end plate 7, the flow path 7e, and the injection space 13. Therefore, the resin 15 can be attached to one or both of the rotor core 3 and the annular member 5 by one end plate 7. In addition, the resin 15 is bent in a crank shape between the injection port 7d, the flow path 7e, and the injection space 13, improving the strength of the attachment of one end plate 7.

[0070] Therefore, the rotor 1 is assembled with the annular member 5, rotor core 3, and end plate 7 attached to each other. After that, the rotor 1 is removed from the upper mold 19 and lower mold 21, and the rotor 1 shown in Figures 1 and 3 is completed. At this time, the resin 15 is folded at the boundary between the upper mold 19 and the rotor 1 based on the cross-sectional shape of the discharge port 19a.

[0071] As described above, the manufacturing method of the rotor 1 in this embodiment involves arranging a columnar rotor core 3 inside an annular member 5, with the end 5a of the annular member 5 protruding axially from the end 3a of the rotor core 3. An end plate 7 with a higher coefficient of thermal expansion than the annular member 5 is placed inside the end 5a of the annular member 5. Then, according to the difference in thermal expansion between the annular member 5 and the end plate 7, the space between the end plate 7 and the annular member 5 is sealed, and the flow path 7e of the resin 15 leading to the injection space 13 is partitioned.

[0072] Therefore, in this embodiment, by utilizing the end plate 7 remaining on the rotor 1 to seal the end 5a of the annular member 5 and partition the flow path 7e of the resin 15, leakage of the resin 15 can be easily and reliably suppressed, and the resin 15 can be reliably injected into the injection space 13. As a result, the annular member 5 can be stably attached to the outer circumference of the rotor core 3.

[0073] Furthermore, when the resin 15 is injected, the magnets 11 and iron core 9 of the rotor core 3 are held between the end plates 7 from both sides in the axial direction, thereby suppressing unintended movement of the magnets 11.

[0074] Furthermore, the end plate 7 is concentric with respect to the rotor core 3 when the resin 15 is injected, ensuring that the balance of the rotor core 3 can be reliably corrected. Since the end plate 7 can be assembled into the end 5a of the annular member 5 before the resin 15 is injected, problems such as being unable to assemble the parts, which can occur when assembling them after the resin 15 has hardened, can be suppressed.

[0075] In this embodiment, after the end plate 7 is fitted into the end 5a of the annular member 5, the end plate 7 is heated together with the annular member 5, and due to the difference in thermal expansion, it is tightly fitted into the end 5a of the annular member 5. This allows for a sealed space between the end plate 7 and the annular member 5.

[0076] Therefore, the end plate 7 can be easily attached to the end portion 5a of the annular member 5, while the leakage of the resin 15 can be easily and reliably suppressed.

[0077] The end plate 7 expands the diameter of the end 5a of the annular member 5 in accordance with the difference in thermal expansion relative to the annular member 5, thereby expanding the injection space 13 at the end 3a of the rotor core 3. Therefore, the resin 15 can be injected into the injection space 13 before the resin 15 begins to harden.

[0078] Furthermore, in this embodiment, the annular member 5 is expanded in diameter relative to the rotor core 3 by injecting the resin 15, and the resin 15 is cured while the annular member 5 is in the expanded state. Therefore, the annular member 5 can be attached to the rotor core 3 by interference fit.

[0079] Furthermore, in this embodiment, the injection space 13 can be expanded at the end 3a of the rotor core 3, ensuring that the resin 15 is reliably injected into the injection space 13. As a result, the annular member 5 can be reliably enlarged in diameter relative to the rotor core 3 by the injected resin 15. Consequently, a secure interlocking fit between the annular member 5 and the rotor core 3 can be achieved.

[0080] Furthermore, the resin 15 hardens throughout the injection port 7d, the flow path 7e, and the injection space 13, improving the bonding strength between the rotor core 3, the annular member 5, and the end plate 7.

[0081] Figure 13 is a cross-sectional view showing a part of the rotor manufacturing apparatus according to Embodiment 2 of the present invention. In Embodiment 2, the basic configuration is the same as that of Embodiment 1, and components corresponding to those in Embodiment 1 are indicated by the same reference numerals, and redundant explanations are omitted.

[0082] In this embodiment, compared to Embodiment 1, the end plate 7 demarcates a vent 7f that extends outside the flow path 7e, for example, toward the inner circumference. The vent 7f is provided in the end plate 7 in a groove shape and forms a closed cross-sectional passage between it and the rotor core 3. This vent 7f communicates with the flow path 7e and extends to the communication hole 7a on the inner circumference of the end plate 7. As a result, the vent 7f allows air and other elements to escape from the flow path 7e. Note that the vent 7f does not necessarily have to extend to the communication hole 7a of the end plate 7. Otherwise, it is the same as Embodiment 1.

[0083] In Embodiment 2, with this configuration, when the resin 15 is injected, air in the flow path 7e and injection space 13 is discharged to the outside through the vent 7f. This ensures that the resin 15 is reliably injected into the injection space 13. In addition, the same effects and advantages as in Embodiment 2 can be achieved.

[0084] Figure 14 is a cross-sectional view showing a part of the rotor manufacturing apparatus according to Embodiment 3 of the present invention. In Embodiment 3, the basic configuration is the same as that of Embodiments 1 and 2, and components corresponding to Embodiments 1 and 2 are indicated by the same reference numerals, and redundant explanations are omitted.

[0085] In this embodiment, unlike in embodiment 2, the injection port 7d of the end plate 7 is provided with a guide surface 7da. That is, the injection port 7d in this embodiment is a hole that penetrates the end plate 7 along the axial direction.

[0086] The guide surface 7da is made up of a part of the inner surface of the injection port 7d and is directed toward the injection space 13. The orientation of the guide surface 7da is such that one end (upper end) of the guide surface 7da located on the surface 7b side of the end plate 7 is offset from the other end (lower end) of the guide surface 7da located on the back surface 7c side of the end plate 7 to a position closer to the injection space 13 that is relatively close to the injection port 7d. The relatively close injection space 13 is the part of the circumferential injection space 13 that is close to the injection port 7d into which the resin 15 is expected to flow.

[0087] In this embodiment, the guide surface 7da is located radially outside the inlet 7d and consists of a flat inclined surface that gradually increases the cross-sectional shape of the inlet 7d toward the outer circumference, starting from the axial middle portion of the inlet 7d toward the flow path 7e. The guide surface 7da may also be composed of a curved surface.

[0088] In this embodiment 3, the resin 15 from the injection port 7d can be guided by the guide surface 7da and flowed toward the injection space 13, thereby suppressing pressure loss during resin 15 injection. As a result, the resin 15 can be reliably injected into the injection space 13. Furthermore, this embodiment can achieve the same effects as embodiments 1 and 2.

[0089] [Modified Example] Figure 15 is a cross-sectional view showing a part of the rotor manufacturing apparatus according to a modified example of Embodiment 3.

[0090] In the modified example shown in Figure 15, the inlet 7d consists of a hole inclined axially toward the injection space 13, and the guide surface 7da is the inner surface of the hole. The inclination of the inlet 7d toward the injection space 13 is such that one end (upper end) of the inlet 7d on the back surface 7c of the end plate 7 is biased toward the portion of the injection space 13 that is relatively close to one end (upper end) of the inlet 7d on the front surface 7b of the end plate 7.

[0091] In this modified example, the injection port 7d is inclined outward from the upper end to the lower end, and the inner surfaces on both radial sides of the inclined injection port 7d form a guide surface 7da consisting of inclined surfaces. In this modified example, the resin 15 can be flowed toward the injection space 13 side across the entire injection port 7d, and the pressure loss during injection of the resin 15 can be suppressed more reliably.

[0092] Figure 16 is a cross-sectional view showing a part of a rotor manufacturing apparatus according to another modification of Example 3.

[0093] In the modified example shown in Figure 16, the end plate 7 comprises a first plate portion 25a and a second plate portion 25b. The first plate portion 25a is positioned proximal to the rotor core 3 in the axial direction. The second plate portion 25b is positioned distal to the rotor core 3 in the axial direction. Specifically, the first plate portion 25a and the second plate portion 25b are stacked in this order on the end face 3a of the rotor core 3.

[0094] The first plate portion 25a is disc-shaped with the same outer diameter as the rotor core 3 and has a guide surface 7db on its outer circumference. The outer diameter of the first plate portion 25a may be smaller than that of the rotor core 3, or larger than that of the rotor core 3 to the extent that it does not block the injection space 13.

[0095] The second plate portion 25b is disc-shaped with an outer diameter that fits onto the end portion 5a of the annular member 5. This second plate portion 25b is provided with an inlet 7d facing the guide surface 7db. The inlet 7d is configured as an inclined hole, similar to the modified example in Figure 15, but it may also be a non-inclined hole as in Embodiment 1.

[0096] The guide surface 7db is an inclined surface that faces the injection port 7d in the axial direction and gradually widens the axial gap between the injection port 7d and the first plate portion 25a toward the injection space 13.

[0097] In this modified example, the inclination of the guide surface 7db, in addition to the inclination of the injection port 7d, allows the resin to flow toward the injection space 13, thereby more reliably suppressing pressure loss during injection of the resin 15.

[0098] 1 Rotor 3 Rotor core 5 Annular member 5a End portion 7 End plate 7d Injection port 7da Guide surface 7e Flow path 7f Vent 11 Magnet 13 Injection space 15 Resin 25a First plate portion 25b Second plate portion

Claims

1. A method for manufacturing a rotor, comprising:

1. Placing a columnar rotor core inside an annular member; allowing the end of the annular member to protrude axially from the end of the rotor core; 2. Placing an end plate with a higher coefficient of thermal expansion than the annular member within the end of the annular member; 3. Sealing the space between the end plate and the annular member according to the difference in thermal expansion between the annular member and the end plate; 4. Defining the flow path of resin leading to the injection space between the annular member and the rotor core; 5. Injecting the resin into the injection space from the demarcated flow path and curing it, leaving the end plate at the end of the annular member.

2. A method for manufacturing a rotor according to claim 1, wherein after the end plate is fitted into the end of the annular member, the end plate is heated together with the annular member and the difference in thermal expansion causes it to tightly fit into the end of the annular member, thereby sealing the space between the end plate and the annular member.

3. A method for manufacturing a rotor according to claim 1, wherein the end plates are arranged within the ends of the annular member on both sides in the axial direction, sealing between the end plates and the annular member is performed on both sides in the axial direction, and the partitioning of the flow path is performed on one side in the axial direction.

4. A method for manufacturing a rotor according to claim 1, wherein the end plate expands the diameter of the end of the annular member in accordance with the difference in thermal expansion, and expands the injection space at the end of the rotor core.

5. A method for manufacturing a rotor according to claim 1, comprising: injecting the resin to expand the diameter of the annular member relative to the rotor core, and curing the resin while expanding the diameter of the annular member.

6. A method for manufacturing a rotor according to any one of claims 1 to 5, wherein the end plate has an injection port for the resin into the flow path, and the injection port has a guide surface directed toward the injection space.

7. A method for manufacturing a rotor according to claim 6, wherein the injection port is a hole inclined with respect to the axial direction toward the injection space, and the guide surface is the inner surface of the hole.

8. A method for manufacturing a rotor according to claim 6, wherein the end plate comprises a first plate portion proximal to the rotor core in the axial direction and a second plate portion distal to the rotor core in the axial direction, the injection port is provided penetrating the second plate portion, and the guide surface is provided on the first plate portion and faces the injection port in the axial direction, and is an inclined surface that gradually widens the axial gap between the injection port and the first plate portion toward the injection space.

9. A method for manufacturing a rotor according to any one of claims 1 to 5, wherein the end plate demarcates a vent extending outside the flow path.

10. A rotor comprising: a columnar rotor core; an annular member having an interior in which the rotor core is arranged and an end projecting axially from the end of the rotor core; an end plate disposed within the end of the annular member and having a higher coefficient of thermal expansion than the annular member; a flow path partitioned by the end plate and leading to an injection space between the annular member and the rotor core; an injection port of the flow path penetrating the end plate; and a resin cured across the injection port, the flow path, and the injection space.

11. A rotor according to claim 10, wherein the injection port has a guide surface directed toward the injection space.

12. A rotor according to claim 11, wherein the injection port is a hole inclined with respect to the axial direction toward the injection space, and the guide surface is the inner surface of the hole.

13. A rotor according to claim 11, wherein the end plate comprises a first plate portion proximal to the rotor core in the axial direction and a second plate portion distal to the rotor core in the axial direction, the inlet is provided through the second plate portion, and the guide surface is provided on the first plate portion and faces the inlet in the axial direction, and is a slope that gradually widens the axial gap between the inlet and the first plate portion toward the injection space.

14. A rotor according to claim 10, comprising a vent partitioned between the end plate and the rotor core and extending out of the flow path.

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