Rotor manufacturing method

Abstract

To provide a rotary electric machine which reduces windage loss and thereby improves energy conversion efficiency.SOLUTION: A rotor 12 constituting a rotary electric machine 10 has a rotary shaft 18, and a permanent magnet 30. On the rotary shaft 18, a sleeve 32 covering the outer surface of the permanent magnet 30 is mounted. The sleeve 32 is composed of a carbon fiber-reinforced resin. To the outer peripheral wall of the sleeve 32, a resin film 40 is joined through a joint material 38. On the outer peripheral wall of the resin film 40, a plurality of projections 54 are formed. Between the plurality of projections 54, riblets 56 which are recessed relatively to the plurality of projections 54 are formed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotating electric machine including a rotor and a stator, and also to a method for manufacturing a rotor that constitutes a rotating electric machine. [Background technology]

[0002] A rotating electric machine is known that includes a rotor and a stator disposed on the outer periphery of the rotor. Here, the rotor has permanent magnets provided on the outer circumferential wall of a rotating shaft. Patent Documents 1 and 2 disclose configurations that prevent the permanent magnets from falling off the rotating shaft. In the technology disclosed in Patent Document 1, a heat-shrinkable film is provided on the outer surface of the permanent magnet via a protective sheet. In the technology disclosed in Patent Document 2, a sleeve made of carbon fiber reinforced resin is attached to the outer surface of the permanent magnet. The permanent magnet is held on the rotating shaft via the heat-shrinkable film or sleeve.

[0003] A certain clearance is formed between the rotor and the stator. Therefore, an air layer is interposed between the rotor and the stator. When the rotating shaft rotates in this state, an air flow is generated around the rotor. When the rotating shaft rotates at a low speed, the air flow is laminar. In contrast, in aircraft and other aircraft, the rotating shaft is expected to rotate at high speeds. In this case, the air flow becomes turbulent. Under these conditions, the frictional resistance of the rotor against the air layer increases. As a result, so-called windage loss occurs. When the permanent magnets become heated due to this windage loss, the energy conversion efficiency of the rotating electric machine decreases.

[0004] In the technology described in Patent Document 2, riblets are formed on the outer peripheral wall of a sleeve to reduce windage loss. Specifically, a prepreg is deformed into a cylindrical shape to obtain a sleeve, and then a transfer film is wrapped around the outer peripheral wall of the sleeve. A convex pattern is formed in advance on the transfer film, and the convex pattern is transferred to the outer peripheral wall of the sleeve. This forms riblets on the outer peripheral wall. The sleeve is then heat-cured and the transfer film is removed from the sleeve.

[0005] Patent Document 3 describes that an armor made of a non-magnetic material is attached to the outer peripheral surface of the rotor. An annular protrusion is formed on the outer peripheral wall of the armor to promote heat dissipation. An annular recess that is recessed relative to the annular protrusion is a groove. According to the description in Patent Document 3, the groove suppresses an increase in windage loss. Titanium is exemplified as a material for the armor. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-136692 [Patent Document 2] Japanese Patent Publication No. 2020-175603 [Patent Document 3] Japanese Patent Application Publication No. 11-150896 Summary of the Invention [Problem to be solved by the invention]

[0007] It is not easy to form a microstructure with high dimensional accuracy in a prepreg. Therefore, even if a fine irregularity is formed on a transfer film, it is not easy to transfer the fine irregularity to a prepreg. For these reasons, it is difficult to obtain a sleeve made of carbon fiber reinforced resin and having fine grooves.

[0008] Patent Document 2 describes the deposition and fixation of fine particles by thermal spraying or cold spraying to obtain an armor with fine irregularities formed on the outer peripheral wall. However, it is not easy to obtain an armor with sufficient rigidity to hold a permanent magnet using such a method. While rigidity can be ensured by using a cylindrical body made of a metal such as titanium as the armor, it is not easy to form fine irregularities by machining or the like titanium. Furthermore, in this case, the weight of the armor is large, which increases the weight of the rotor.

[0009] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0010] According to one embodiment of the present invention, there is provided a rotating electric machine comprising a rotor and a stator, wherein the rotor has a rotating shaft and a permanent magnet held by the rotating shaft, and the stator has an electromagnetic coil surrounding the permanent magnet, wherein the rotor comprises a sleeve that covers the outer surface of the permanent magnet on the rotating shaft and is spaced a predetermined distance from the stator, and a resin film bonded to the outer wall of the sleeve via a bonding material, wherein the sleeve is made of carbon fiber reinforced resin, a protrusion structure is formed on the outer wall of the resin film, the protrusion structure consists of one or more convex portions that form a plurality of protrusions extending parallel to each other, and riblets that are recessed relative to the plurality of protrusions are formed between the plurality of protrusions.

[0011] According to another embodiment of the present invention, there is provided a method for manufacturing a rotor having a rotating shaft and a permanent magnet held by the rotating shaft, and being surrounded by a stator in a rotating electric machine, the method comprising: a sleeve mounting process for covering the outer surface of the permanent magnet with a sleeve made of carbon fiber reinforced resin; and a joining process for joining a resin film to the outer peripheral wall of the sleeve via a joining material, wherein a protrusion structure is formed in advance on the outer peripheral wall of the resin film, and by performing the joining process, the protrusion structure is formed as one or more convex portions that form multiple protrusions extending parallel to each other, and a rotor is obtained in which riblets that are formed between the multiple protrusions are recessed relative to the multiple protrusions. [Effects of the Invention]

[0012] Since it is difficult to process a sleeve made of carbon fiber reinforced resin, it is not easy to form riblets (or protrusions) on the outer wall of the sleeve. In contrast, in the present invention, riblets are formed in a resin film that covers the outer wall of the sleeve. Because the resin film is separate from the sleeve, there is no need to perform processing such as cutting on the sleeve. Therefore, damage such as cracks to the sleeve is avoided.

[0013] For example, by transferring a fine pattern provided on a mold to a resin film, fine protrusions and riblets can be easily formed. Moreover, the resin film is made of a resin that is lighter than metals, etc. This prevents the rotor from becoming too heavy.

[0014] The riblets reduce the turbulent vortices that occur around the rotor, even when the rotor rotates at high speed. This reduces turbulent friction viscosity and suppresses the generation of tiller vortices. For these reasons, windage loss can be reduced. As a result, heating of the permanent magnets is suppressed. Therefore, a decrease in the magnetic force of the permanent magnets is avoided, and the energy conversion efficiency of the rotating electric machine is sufficiently increased. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic cross-sectional view of a rotating electric machine according to an embodiment of the present invention, viewed along the axial direction. [Figure 2] FIG. 2 is a schematic front view of the rotor as viewed from the axial direction. [Figure 3] 1 is an example of an enlarged view of a main part of a resin film when viewed along the axial direction of a rotating shaft of a rotor. [Figure 4] FIG. 4 is another example of an enlarged view of a main part of the resin film when viewed along the axial direction of the rotating shaft of the rotor. [Figure 5] FIG. 5 is another example of an enlarged view of a main part of the resin film when viewed along the axial direction of the rotating shaft of the rotor. [Figure 6] FIG. 6 is an example of a cross-sectional view of a protrusion formed on a resin film, as viewed from a direction perpendicular to the extending direction of the protrusion. [Figure 7] FIG. 7 is another example of a cross-sectional view of a protrusion formed on a resin film, as viewed from a direction perpendicular to the extending direction of the protrusion. [Figure 8] FIG. 8 is another example of a cross-sectional view of a protrusion formed on a resin film, as viewed from a direction perpendicular to the extending direction of the protrusion. [Figure 9] FIG. 9 is yet another example of a cross-sectional view of a protrusion formed on a resin film, as viewed from a direction perpendicular to the extending direction of the protrusion. [Figure 10] FIG. 10 is yet another example of a cross-sectional view of a protrusion formed on a resin film, as viewed from a direction perpendicular to the extending direction of the protrusion. [Figure 11] 1 is a schematic flow diagram of a rotor manufacturing method according to an embodiment of the present invention. [Figure 12] FIG. 12 is a schematic side view showing a state in which the divided pieces of the sleeve are being passed over a rotating shaft on which a permanent magnet is provided. [Figure 13] FIG. 13 is a schematic side view showing a state in which cutting is being performed on a sleeve attached to a rotating shaft. [Figure 14] FIG. 14 is a schematic side view showing a state in which the outer peripheral walls of the divided pieces of the sleeve are aligned. [Figure 15] FIG. 15 is a schematic side view showing a state in which a resin film is being bonded to a sleeve attached to a rotating shaft. [Figure 16] FIG. 16 is a schematic side view of a resin film to which a heat-resistant double-sided tape, which is an example of a bonding material, has been previously bonded, as viewed in the thickness direction. [Figure 17] FIG. 17 is a schematic side view showing a state in which a load is applied to a resin film by a pressure roller. [Figure 18] FIG. 18 is a schematic side view showing a state in which a heat-resistant adhesive, which is an example of a bonding material, is applied to the outer peripheral wall of the sleeve. [Figure 19] FIG. 19 is a schematic side view showing a state in which a resin film is irradiated with ultraviolet rays. DETAILED DESCRIPTION OF THE INVENTION

[0016] 1 to 13, some components may be exaggerated to facilitate understanding, and therefore, the actual scale of each component is not shown in FIGS.

[0017] 1 is a schematic cross-sectional view of a rotating electrical machine 10 according to this embodiment, viewed along an axial direction (described later). The rotating electrical machine 10 includes a rotor 12 and a stator 14. Most of the rotor 12 and the stator 14 are housed in a casing 16.

[0018] The rotor 12 has a rotating shaft 18. The rotating shaft 18 is a cylindrical body having a first small diameter portion 20, a large diameter portion 22, and a second small diameter portion 24. The centers of the first small diameter portion 20 and the second small diameter portion 24 coincide with the center of the large diameter portion 22. The direction in which the first small diameter portion 20, the large diameter portion 22, and the second small diameter portion 24 are aligned is the extension direction of the rotating shaft 18. Hereinafter, a line passing through the centers of the first small diameter portion 20, the large diameter portion 22, and the second small diameter portion 24 and extending along the extension direction of the rotating shaft 18 will be referred to as the axis M, and a direction parallel to the axis M will sometimes be referred to as the axial direction. The axial direction is the direction of arrow X in FIG. 1. The diameters of the first small diameter portion 20, the large diameter portion 22, and the second small diameter portion 24 each extend in a direction perpendicular to the axis M. Hereinafter, the direction in which the diameters extend will sometimes be referred to as the diameter direction. The diameter direction is the direction of arrow Y in FIG.

[0019] The rotating shaft 18 is rotatably supported by the casing 16 via a first bearing 26 and a second bearing 28. The tips of the first small diameter portion 20 and the second small diameter portion 24 of the rotating shaft 18 are passed through the first bearing 26 and the second bearing 28, respectively, and are exposed from the casing 16. To the tips exposed from the casing 16, for example, a propeller (not shown) is attached.

[0020] As shown in FIGS. 1 and 2, a permanent magnet 30 is disposed on the outer periphery of the large diameter portion 22. A sleeve 32 is further provided on the rotating shaft 18. In this embodiment, the sleeve 32 has a first sleeve piece 34a, a second sleeve piece 34b, and a third sleeve piece 34c. Each of the first sleeve piece 34a, the second sleeve piece 34b, and the third sleeve piece 34c is a ring-shaped segment. That is, in this case, the sleeve 32 has a plurality of segments. The first sleeve piece 34a, the second sleeve piece 34b, and the third sleeve piece 34c are substantially congruent with one another.

[0021] The first sleeve piece 34a, the second sleeve piece 34b, and the third sleeve piece 34c are aligned along the axial direction of the rotating shaft 18. One end face of the first sleeve piece 34a abuts against one end face of the second sleeve piece 34b. Similarly, the other end face of the second sleeve piece 34b abuts against one end face of the third sleeve piece 34c. The sleeve 32 is formed by the first sleeve piece 34a, the second sleeve piece 34b, and the third sleeve piece 34c being aligned in a straight line and abutting against each other as described above.

[0022] The first sleeve piece 34a, the second sleeve piece 34b, and the third sleeve piece 34c are made of carbon fiber reinforced plastic (CFRP) and exhibit a certain degree of elasticity. CFRP is formed by impregnating carbon fibers with a matrix resin. An example of a suitable matrix resin is an epoxy resin. The glass transition temperature of epoxy resin is typically around 180°C.

[0023] The first sleeve piece 34a, the second sleeve piece 34b, and the third sleeve piece 34c, which are aligned along the axial direction of the rotating shaft 18, cover the outer surface of the permanent magnet 30. No external force is applied to the first sleeve piece 34a, the second sleeve piece 34b, and the third sleeve piece 34c before they are inserted onto the rotating shaft 18. This state is known as the natural state. The inner diameters of the first sleeve piece 34a, the second sleeve piece 34b, and the third sleeve piece 34c in the natural state are slightly smaller than the sum of the outer diameters of the rotating shaft 18 and the permanent magnet 30. Therefore, when the rotating shaft 18 is inserted, the first sleeve piece 34a, the second sleeve piece 34b, and the third sleeve piece 34c elastically deform so as to slightly expand in diameter. Thereafter, the first sleeve piece 34a, the second sleeve piece 34b, and the third sleeve piece 34c slightly contract in diameter due to their elastic restoring force. Due to this elastic restoring force, the first sleeve piece 34a, the second sleeve piece 34b, and the third sleeve piece 34c press the permanent magnet 30 toward the rotating shaft 18. Based on this pressing force, the permanent magnet 30 is held by the sleeve 32 on the outer periphery of the rotating shaft 18. The thickness of each of the first sleeve piece 34a, the second sleeve piece 34b, and the third sleeve piece 34c is typically about 0.5 mm to 5 mm.

[0024] As shown in Fig. 1, the stator 14 has an electromagnetic coil 36. The electromagnetic coil 36 is provided in a stator core (not shown). When the stator 14 is positioned and fixed to the casing 16 and the portion of the rotor 12 on which the permanent magnets 30 are provided is housed in the casing 16, the electromagnetic coil 36 surrounds the permanent magnets 30 via the sleeve 32. When the permanent magnets 30 and the rotating shaft 18 rotate integrally, an alternating magnetic field is generated between the permanent magnets 30 and the electromagnetic coil 36.

[0025] 1 and 2, a resin film 40 is bonded to the outer peripheral wall of the sleeve 32 via a bonding material 38. Suitable examples of the bonding material 38 include a heat-resistant double-sided tape 42 shown in FIG. 16 and a heat-resistant adhesive 44 shown in FIG. 18.

[0026] The resin film 40 covers the entire outer peripheral wall of the sleeve 32. As can be seen from Fig. 1, the sleeve 32 and the electromagnetic coil 36 are spaced apart by a predetermined distance. Therefore, an air layer AL is present between the sleeve 32 and the electromagnetic coil 36.

[0027] FIG. 3 is an enlarged view of a main portion of the resin film 40 when viewed along the axial direction of the rotating shaft 18. In this embodiment, the resin film 40 has an inner layer 50 (see FIGS. 1 and 2) and an outer layer 52. Both the inner layer 50 and the outer layer 52 are made of resin. The inner layer 50 is preferably made of a resin with excellent heat resistance. A specific example of such a resin is polycarbonate. On the other hand, the outer layer 52 is preferably made of a resin that is easy to form a fine pattern on, is easily bonded to the inner layer 50, and has excellent heat resistance. A specific example of such a resin is an ultraviolet-curable resin such as an epoxy resin. Note that the inner layer 50 and the outer layer 52 do not contain reinforcing fibers such as carbon fibers.

[0028] A protrusion structure is formed on the outer peripheral wall of the outer layer 52. In the embodiment shown in FIG. 3, the protrusion structure consists of a plurality of convex portions that protrude annularly outward in the diametric direction of the rotating shaft 18. One convex portion forms one protrusion 54. Therefore, the protrusion structure shown in FIG. 3 has a plurality of protrusions 54 formed from a plurality of convex portions. The multiple convex portions are arranged so as to be spaced apart at approximately equal intervals from each other, so that two adjacent protrusions 54 of the multiple protrusions 54 extend parallel to each other. Between two adjacent protrusions 54 is a groove that is recessed relative to these two protrusions 54. In other words, a plurality of grooves are formed in the outer layer 52. The multiple grooves form riblets 56 that are recessed relative to the protrusions 54.

[0029] In the embodiment shown in Fig. 3, each protrusion 54 is perpendicular to the axial direction of the rotary shaft 18. That is, in this case, the intersection angle θ between the extension direction of the protrusion 54 and the axial direction of the rotary shaft 18 is 90°. Therefore, the protrusions 54 protrude outward in the radial direction of the rotary shaft 18 and the sleeve 32. However, the intersection angle θ may be 45° or greater and is not limited to 90°. For example, the intersection angle θ may be 75° as shown in Fig. 4 or 60° as shown in Fig. 5.

[0030] 4 and 5, it is also possible to form a spirally extending protrusion structure by forming one protrusion in a spiral shape. Even in this case, when the rotating shaft 18 is viewed along the axial direction, multiple protrusions 54 appear on the resin film 40. In other words, this configuration represents "multiple protrusions formed from one protrusion." Therefore, this configuration is also included in the "multiple protrusions" in this specification.

[0031] 6 is a schematic vertical cross-sectional view of the sleeve 32 and the resin film 40 cut along a direction perpendicular to the extending direction of the protrusions 54. In the embodiment shown in FIG. 6, the extending direction of the protrusions 54 corresponds to the diameter direction of the rotating shaft 18.

[0032] As shown in Figure 6, in this case, a cross section along the protruding direction of the protrusion 54 appears. The cross-sectional shape of the protrusion 54 in this case is typically an isosceles triangle. Figure 6 illustrates an example in which the angle α of the apex 58 of the protrusion 54 that protrudes most radially outward from the rotary shaft 18 is 30°. However, α is not limited to 30°. As shown in Figure 7, α may be 45°. As shown in Figure 8, α may be 90°.

[0033] As shown in Fig. 9, the cross section of the protrusions 54 may be wave-shaped with rounded valley portions. As shown in Fig. 10, the cross section of the protrusions 54 may be columnar (or rod-shaped). As can be understood with reference to Figs. 6 to 10, the riblets 56 may be any of concave grooves with flat bottoms (Figs. 6, 7 and 10), V-shaped grooves (Fig. 8), or round grooves with arc-shaped curved bottoms (Fig. 9).

[0034] The distance S between the apex 58 of one protrusion 54 and the apex 58 of the protrusion 54 adjacent to that protrusion 54 is defined as the pitch. In order to sufficiently suppress windage loss when the rotating shaft 18 rotates at high speed, the pitch S is preferably 100 μm or less. However, if the pitch S is excessively small, it is difficult to form the protrusions 54. Therefore, the pitch S is preferably set within the range of 20 μm to 60 μm.

[0035] Furthermore, the distance H from the valley to the peak 58 of one protrusion 54 is defined as the height of the protrusion 54. In order to sufficiently reduce windage loss while sufficiently increasing the aspect ratio of the riblets 56, the height H is preferably 50 μm or less. Furthermore, it is preferable that the following relationship hold between the height H and the pitch S: H=0.5S When the pitch S is within the range of 20 μm to 60 μm, the preferred range of the height H is 10 μm to 30 μm.

[0036] The rotating electric machine 10 configured as described above is mounted on, for example, an aircraft and used as a motor. When the motor is driven, current is passed through the electromagnetic coil 36 shown in FIG. 1. This current passage generates a magnetic field around the electromagnetic coil 36. A repulsive or attractive force acts between this magnetic field and the permanent magnet 30, causing the rotating shaft 18 to begin rotating about the axis M. This generates a flow in the air layer AL between the stator 14 and the resin film 40.

[0037] In an aircraft, a motor may be required to rotate at high speed. In this embodiment, riblets 56 are formed on the resin film 40 provided on the outer peripheral wall of the sleeve 32. Furthermore, the pitch S between two adjacent protrusions 54 forming the riblets 56 is preferably 100 μm or less. Therefore, even when the rotating shaft 18 rotates at high speed, turbulent vortices generated around the rotor 12 are reduced. This reduces turbulent friction viscosity and suppresses the generation of tiller vortices. For these reasons, windage loss can be reduced.

[0038] That is, according to this embodiment, windage loss is sufficiently suppressed. As a result, heating of the permanent magnets 30 is suppressed. Therefore, a decrease in the magnetic force of the permanent magnets 30 is avoided, and the energy conversion efficiency of the rotating electric machine 10 is sufficiently increased. That is, the electrical energy input to the electromagnetic coil 36 is efficiently converted into a driving force that rotates the rotating shaft 18.

[0039] When the rotating electric machine 10 is used as a generator, the driving force that rotates the rotating shaft 18 is efficiently converted into electrical energy that is output from the electromagnetic coil 36. As described above, according to this embodiment, the response characteristics of the rotating electric machine 10 are improved.

[0040] When the inner layer 50 and the outer layer 52 of the resin film 40 are made of a heat-resistant resin, the resin film 40 exhibits excellent heat resistance. Therefore, the shape of the protrusions 54 is maintained even when the rotor 12 rotates at high speed. Moreover, the resin film 40 is firmly bonded to the sleeve 32 made of carbon fiber reinforced resin by the bonding material 38. Therefore, even when the rotor 12 rotates at high speed, the resin film 40 is prevented from falling off the sleeve 32. For these reasons, an increase in windage loss during operation of the rotating electric machine 10 can be avoided, even when the rotating electric machine 10 is operated continuously for a long period of time.

[0041] Next, a method for manufacturing the rotor 12 that constitutes the rotating electrical machine 10 will be described. Here, as shown in the schematic flow of Fig. 11, a case will be described in which a sleeve mounting process ST1, a cutting process ST2, a joining process ST3, and an ultraviolet light irradiation process ST4 are performed.

[0042] To obtain the sleeve 32 made of carbon fiber reinforced resin, the prepreg is bent into a cylindrical shape and heat is applied to the prepreg in this state. This hardens the matrix resin in the prepreg, thereby obtaining the first sleeve piece 34a. The second sleeve piece 34b and the third sleeve piece 34c are produced in a similar manner. The axial lengths of the first sleeve piece 34a to the third sleeve piece 34c are shorter than the axial length of the sleeve 32. For this reason, it is easier to produce the first sleeve piece 34a to the third sleeve piece 34c than to produce the sleeve 32 as a single member. The thickness of each of the first sleeve piece 34a to the third sleeve piece 34c is, for example, approximately 0.5 mm to 5 mm.

[0043] First, in the sleeve attachment step ST1, the outer surface of the permanent magnet 30 is covered with the first to third sleeve pieces 34a to 34c obtained as described above. That is, as shown in FIG. 12, the first to third sleeve pieces 34a to 34c are sequentially passed through the large diameter portion 22 on which the permanent magnet 30 is provided. One end face of the second sleeve piece 34b abuts against one end face of the first sleeve piece 34a. One end face of the third sleeve piece 34c abuts against the other end face of the second sleeve piece 34b. In this way, the first to third sleeve pieces 34a to 34c are aligned along the axial direction of the rotating shaft, and the sleeve 32 is formed.

[0044] When the first to third sleeve pieces 34a to 34c are passed through the large diameter portion 22, they expand slightly in diameter due to elastic deformation, and then contract slightly in diameter due to elastic restoring force. As a result, the sleeve 32 presses the permanent magnet 30 toward the center of the rotating shaft 18. Accordingly, the permanent magnet 30 is held on the outer periphery of the large diameter portion 22 by the sleeve 32, as shown in FIG.

[0045] The first to third sleeve pieces 34a to 34c may have different outer diameters due to manufacturing errors. Alternatively, the centers of the first to third sleeve pieces 34a to 34c may not be aligned. In such cases, as shown in FIG. 13, steps 60 are formed between the first sleeve piece 34a and the second sleeve piece 34b and between the second sleeve piece 34b and the third sleeve piece 34c. FIG. 13 shows a state in which the outer diameters and centers of the first sleeve piece 34a and the third sleeve piece 34c are aligned, and the second sleeve piece 34b is eccentric relative to the first sleeve piece 34a and the third sleeve piece 34c.

[0046] If the step 60 is outside the allowable range, the first to third sleeve pieces 34a to 34c are cut in the cutting process ST2. Specifically, the first small diameter portion 20 and the second small diameter portion 24 of the rotating shaft 18 are supported by a rotation mechanism 70. In this state, while the rotating shaft 18 is rotated about the axis M, a cutting tool 72 (such as an end mill or cutting tool) shown in FIG. 13 is brought into sliding contact with the sleeve 32. This cuts off portions of the outer circumferential walls of the first to third sleeve pieces 34a to 34c. In other words, the first to third sleeve pieces 34a to 34c are thinned.

[0047] As a result, as shown in Figure 14, a sleeve 32 is obtained in which the step 60 is within the allowable range. If the step 60 is within the allowable range when the sleeve 32 is formed, there is no particular need to perform the cutting process step ST2. In this case, after the sleeve attachment step ST1 is completed, the process moves to the joining step ST3. Before performing the joining step ST3, the outer peripheral wall of the sleeve 32 may be subjected to a surface treatment to improve the joining strength.

[0048] Next, in the bonding step ST3, as shown in Fig. 15, the resin film 40 prepared in advance is bonded to the outer peripheral wall of the sleeve 32 while the rotating shaft 18 is rotated at a low speed. For the reasons described above, it is preferable to bond the resin film 40 to the outer peripheral wall of the sleeve 32 so that the intersecting angle θ (see Figs. 3 to 5) between the extending direction of the protrusions 54 formed in advance on the outer layer 52 and the axial direction of the rotating shaft 18 is 45° to 90°.

[0049] When the heat-resistant double-sided tape 42 shown in Fig. 16 is used as the bonding material 38, one end surface of the heat-resistant double-sided tape 42 is previously bonded to the inner layer 50. Thereafter, the other end surface of the heat-resistant double-sided tape 42 is bonded to the outer peripheral wall of the sleeve 32. After the resin film 40 has been bonded to the outer peripheral wall of the sleeve 32 via the heat-resistant double-sided tape 42 in this manner, as shown in Fig. 17, a pressure roller 74 is pressed against the resin film 40 while the rotating shaft 18 is rotated at a low speed.

[0050] When the heat-resistant adhesive 44 shown in FIG. 18 is used as the bonding material 38, for example, the application roller 76 is pressed against the resin film 40 while the rotating shaft 18 is rotated at a low speed. At this time, the heat-resistant adhesive 44 exudes from the application roller 76. As the rotating shaft 18 is rotating, the heat-resistant adhesive 44 is applied to the entire outer peripheral wall of the sleeve 32. Thereafter, the inner layer 50 of the resin film 40 is bonded to the outer peripheral wall of the sleeve 32 via the heat-resistant adhesive 44. Furthermore, as in FIG. 17, the rotating shaft 18 is rotated at a low speed while the pressure roller 74 is pressed against the resin film 40.

[0051] For example, when the length of the resin film 40 along the axial direction of the sleeve 32 is greater than the axial length of the sleeve 32, the resin film 40 is cut before being joined to the sleeve 32. Alternatively, the resin film 40 may be cut after being joined to the sleeve 32.

[0052] Protrusions 54 are formed in advance on the outer layer 52 of the resin film 40 as shown in Figures 3 to 10. A groove is formed between two adjacent protrusions 54, recessed relative to the two protrusions 54. Therefore, by joining the resin film 40 to the outer peripheral wall of the sleeve 32 in joining step ST3, a rotor 12 having riblets 56 formed thereon is obtained.

[0053] If the material of the outer layer 52 is an ultraviolet curable resin, an ultraviolet irradiation step ST4 is performed. For example, ultraviolet rays UV are irradiated onto the resin film 40 from an ultraviolet lamp 78 shown in FIG. 19. This hardens the outer layer 52, making it easier to maintain the shape of the protrusions 54. In addition, the outer layer 52 is sufficiently bonded to the inner layer 50. Note that if the material of the outer layer 52 is not an ultraviolet curable resin, there is no particular need to perform the ultraviolet irradiation step ST4.

[0054] Thereafter, the rotor 12 is left for a predetermined time, or alternatively, the rotor 12 may be heated. As a result of the above, the rotor 12 is obtained in which the resin film 40 is bonded to the outer peripheral wall of the sleeve 32 and the riblets 56 are formed in the resin film 40.

[0055] As described above, this embodiment discloses a rotating electric machine (10) comprising a rotor (12) and a stator (14), the rotor having a rotating shaft (18) and a permanent magnet (30) held by the rotating shaft, and the stator having an electromagnetic coil (36) surrounding the permanent magnet, the rotor comprising: a sleeve (32) that covers the outer surface of the permanent magnet on the rotating shaft and is spaced a predetermined distance from the stator; and a resin film (40) bonded to the outer peripheral wall of the sleeve via a bonding material (38), the sleeve being made of carbon fiber reinforced resin, a protrusion structure being formed on the outer peripheral wall of the resin film, the protrusion structure being made of one or more convex portions that form a plurality of protrusions (54) extending parallel to one another, and riblets (56) that are recessed relative to the plurality of protrusions are formed between the plurality of protrusions.

[0056] Riblets are formed between two adjacent protrusions. These riblets reduce the turbulent vortices that occur around the rotor, even when the rotor rotates at high speed. This reduces turbulent friction viscosity and suppresses the occurrence of tiller vortices. For these reasons, windage loss can be reduced.

[0057] As a result, the permanent magnets are prevented from being heated, and therefore the magnetic force of the permanent magnets is prevented from decreasing, resulting in a sufficiently high energy conversion efficiency in the rotating electrical machine.

[0058] This embodiment discloses a method for manufacturing a rotor (12) that has a rotating shaft (18) and a permanent magnet (30) held by the rotating shaft and is surrounded by a stator (14) in a rotating electric machine (10), the method comprising: a sleeve attachment process (ST1) for covering the outer surface of the permanent magnet with a sleeve (32) made of carbon fiber reinforced resin; and a joining process (ST3) for joining a resin film (40) to the outer peripheral wall of the sleeve via a joining material (38), in which a protrusion structure is formed in advance on the outer peripheral wall of the resin film, and by performing the joining process, a rotor is obtained in which the protrusion structure is formed as one or more convex portions that form a plurality of protrusions (54) extending parallel to each other, and riblets (56) that are formed between the plurality of protrusions and are recessed relative to the plurality of protrusions.

[0059] In this embodiment, the sleeve is made of carbon fiber reinforced resin. Furthermore, the sleeve is generally thin-walled. It is generally difficult to perform machining, such as cutting, on thin-walled carbon fiber reinforced resin. Therefore, it is not easy to form protrusions on the outer peripheral wall of the sleeve.

[0060] In contrast, in this embodiment, the sleeve is covered with a resin film, and protrusions are formed on this resin film. Therefore, by joining the resin film to the sleeve, riblets are formed on the resin film covering the outer peripheral wall of the sleeve. Therefore, there is no need to perform processing such as cutting on the outer peripheral wall of the sleeve. This prevents damage such as cracks from occurring in the sleeve.

[0061] This embodiment discloses a rotating electric machine in which the extending direction of the plurality of protrusions intersects with the axial direction (X) of the rotating shaft at an angle (θ) of 45° to 90°.

[0062] This embodiment discloses a rotor manufacturing method in which, in the joining process, the resin film is joined to the sleeve so that the multiple protrusions extend in a direction that intersects the axial direction (X) of the rotating shaft at an angle (θ) of 45° to 90°.

[0063] By setting the intersection angle of the protrusion with respect to the axial direction of the rotating shaft within the above range, turbulence is avoided in the air layer between the sleeve and the stator when the rotor shaft rotates in the rotating electric machine.

[0064] This embodiment discloses a rotating electric machine in which, when the height of each of the plurality of protrusions is H and the pitch between two adjacent protrusions among the plurality of protrusions is S, S is 100 μm or less and the following formula holds: H=0.5S

[0065] This embodiment discloses a method for manufacturing a rotor, in which the plurality of protrusions are formed on the resin film so that the following formula holds, where H is the height of each of the plurality of protrusions and S is the pitch between two adjacent protrusions among the plurality of protrusions. H=0.5S

[0066] By setting the pitch S to 100 μm or less, windage loss can be sufficiently reduced even when the rotor rotates at high speed. Furthermore, by setting the height H to 1 / 2 the pitch S, the aspect ratio of the riblets becomes sufficiently large. This also makes it possible to sufficiently reduce windage loss when the rotor rotates at high speed.

[0067] This embodiment discloses a rotating electric machine in which the cross-sectional shape of the plurality of protrusions is triangular when the plurality of protrusions are cut along a direction perpendicular to the direction in which the plurality of protrusions extend.

[0068] This embodiment discloses a method for manufacturing a rotor, in which the multiple protrusions are formed on the resin film so that when the multiple protrusions are cut along a direction perpendicular to the extension direction of the multiple protrusions, the cross-sectional shape of the multiple protrusions is triangular.

[0069] By making the cross section triangular, the protrusions can be formed more easily than protrusions with other cross sections.

[0070] This embodiment discloses a rotating electric machine in which, when the plurality of protrusions are cut along a direction perpendicular to the extension direction of the plurality of protrusions, the angle (α) of the apex (58) that protrudes most radially outward from the rotating shaft in the cross section of the plurality of protrusions is 30° to 90°.

[0071] This embodiment discloses a method for manufacturing a rotor, in which the plurality of protrusions are formed in the protrusion forming process so that when the plurality of protrusions are cut along a direction perpendicular to the extension direction of the plurality of protrusions, the angle (α) of the apex (58) that protrudes most radially outward from the rotating shaft in the cross section of the plurality of protrusions is 30° to 90°.

[0072] By setting the apex angle within this range, the protrusions can be formed more easily than protrusions with apex angles outside the above range.

[0073] This embodiment discloses a rotating electric machine in which the resin film has an inner layer (50) that covers the outer wall of the sleeve via the bonding material, and an outer layer (52) that covers the outer periphery of the inner layer, and the outer layer is made of ultraviolet-curing resin.

[0074] This embodiment discloses a method for manufacturing a rotor, in which the resin film has an inner layer (50) that covers the outer wall of the sleeve via the bonding material and an outer layer (52) that covers the outer periphery of the inner layer, the outer layer being an ultraviolet-curable resin, and the method further includes an ultraviolet irradiation process (ST4) in which ultraviolet rays (UV) are irradiated onto the outer layer after the bonding process.

[0075] For example, the material of the inner layer can be a resin that can be easily bonded to the carbon fiber reinforced resin via a bonding material, while the material of the outer layer can be a resin that has excellent weather resistance and abrasion resistance. By combining the inner layer and the outer layer in this way, a resin film with excellent properties can be obtained.

[0076] This embodiment discloses a rotary electric machine in which the sleeve has a plurality of divided pieces (34a to 34c) arranged along the axial direction of the rotary shaft.

[0077] This embodiment discloses a method for manufacturing a rotor, in which, in the sleeve mounting process, multiple divided pieces (34a to 34c) are attached to the rotor along the axial direction of the rotating shaft, thereby forming the sleeve from the multiple divided pieces.

[0078] The axial length of the divided pieces is shorter than the axial length of the sleeve. It is easier to produce short divided pieces than to produce a long sleeve made of a single member. In other words, in this case, the sleeve can be easily obtained.

[0079] This embodiment discloses a rotor manufacturing method in which, before the joining step, cutting (ST2) is performed on the plurality of divided pieces to align the positions of the outer peripheral walls of the plurality of divided pieces.

[0080] This makes it possible to obtain a sleeve in which the step on the outer peripheral wall is within the tolerance range, thereby preventing the resin film bonded to the outer peripheral wall of the sleeve from having a step that exceeds the tolerance range.

[0081] The present invention is not limited to the above disclosure, and various configurations can be adopted without departing from the gist of the present invention. [Explanation of symbols]

[0082] 10... Rotating electric machine 12... Rotor 14... Stator 18... Rotating shaft 30...Permanent magnet 32...Sleeve 34a to 34c... Sleeve pieces 36... Electromagnetic coil 38... Bonding material 40... Resin film 42...Heat-resistant double-sided tape 44...Heat-resistant adhesive 50...inner layer 52...outer layer 54...Protrusion 56...Riblet 58...Top 70...Rotation mechanism 72...Cutting tool 74...Pressing roller 76... Application roller 78... Ultraviolet lamp AL...Air layer M...Axis

Claims

1. A method for manufacturing a rotor having a rotating shaft and a permanent magnet held by the rotating shaft, the rotor being surrounded by a stator in a rotating electric machine, comprising: a sleeve attachment step of covering the outer surface of the permanent magnet with a sleeve made of carbon fiber reinforced resin; a joining step of joining a resin film to an outer peripheral wall of the sleeve via a joining material; and a protrusion structure is formed in advance on the outer peripheral wall of the resin film, By performing the joining step, a rotor is obtained in which the protrusion structure is formed as one or more convex portions forming a plurality of protrusions extending parallel to each other, and riblets that are recessed relative to the plurality of protrusions are formed between the plurality of protrusions, the resin film has an inner layer that covers the outer wall of the sleeve via the bonding material, and an outer layer that covers the outer periphery of the inner layer, the outer layer being an ultraviolet-curable resin, and the method for manufacturing a rotor further includes an ultraviolet irradiation step of irradiating ultraviolet light onto the outer layer after the bonding step.

2. 2. The manufacturing method of claim 1, wherein in the joining step, the resin film is joined to the sleeve so that the plurality of protrusions extend in a direction intersecting the axial direction of the rotating shaft at an angle of 45° to 90°.

3. 2. The manufacturing method of claim 1, wherein the plurality of protrusions are formed on the resin film so that the following formula holds: H = 1 / 2 ⁢ ⁢ ⁢ ⁢ H ⁢ ... H=0.5S

4. 2. The rotor manufacturing method according to claim 1, wherein the plurality of protrusions are formed on the resin film so that when the plurality of protrusions are cut along a direction perpendicular to the extension direction of the plurality of protrusions, the cross-sectional shape of the plurality of protrusions is triangular.

5. 2. The manufacturing method of claim 1, wherein the plurality of protrusions are formed on the resin film so that when the plurality of protrusions are cut along a direction perpendicular to the extension direction of the plurality of protrusions, the angle of the apex that protrudes most outward in the diameter direction of the rotating shaft in a cross section of the plurality of protrusions is 30° to 90°.

6. A manufacturing method for a rotor according to any one of claims 1 to 5, wherein in the sleeve mounting step, a plurality of divided pieces are attached to the rotor along the axial direction of the rotating shaft, thereby forming the sleeve from the plurality of divided pieces.

7. 7. The manufacturing method of claim 6, wherein, before the joining step, the plurality of divided pieces are machined to align the positions of the outer peripheral walls of the plurality of divided pieces.

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