Rotor for rotating electrical machine and manufacturing method thereof

Abstract

To provide a highly reliable rotor of a rotary electric machine having high crack resistance in a slot for a magnet under a heat cycle environment by efficiently mitigating stress to resin and a manufacturing method for the same.SOLUTION: A rotor 100 of a rotary electric machine includes a rotor core 1 provided with slots 2 for a magnet along the circumferential direction, a permanent magnet 3 located in the slots 2 for the magnet and fixed with a magnet fixing resin 5, and a stress relaxation layer formed on the surface of the permanent magnet 3 and in which a part of the magnet fixing resin 5 is modified.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present application relates to a rotor for a rotating electric machine and a method for manufacturing the same. [Background technology]

[0002] Interior Permanent Magnet Motors (IPM motors), which have a structure in which permanent magnets are embedded in magnet slots provided in the rotor, are well known as rotating electrical machines. In addition to the electrification of automobiles, recent technological advances in industrial robots and railways have led to demands for higher efficiency and precision in the IPM motors that control these devices.

[0003] Generally, the rotor of an IPM motor is manufactured by stacking multiple core pieces and joining them by crimping or welding, forming magnet slots in the laminated core, inserting permanent magnets into the magnet slots, and then injecting resin into the slots and allowing it to harden to fix the permanent magnets to the laminated core.

[0004] The rotor of an IPM motor is required to have high heat cycle resistance. The rare earth permanent magnets used in IPM motors have high conductivity, and when an AC magnetic field is applied to the permanent magnet, an energy loss called eddy current loss occurs. When this happens, the temperature of the permanent magnet inside the magnet slots in the iron core rotor rises. In addition, assuming use in cold regions, the motor must be able to withstand low-temperature environments of around -40°C.

[0005] The resin, laminated core, and permanent magnets all have different thermal expansion coefficients, so there was concern that under the heat cycle environment described above, stress caused by the difference in linear expansion coefficients could cause cracks in the resin, which could then be scattered as the rotor rotates at high speed.

[0006] As a countermeasure against cracks, for example, Patent Document 1 discloses a permanent magnet fixing method in which one end face of the permanent magnet and one end face of the laminated core form the same plane, exposing the permanent magnet at the end face of the laminated core, thereby allowing displacement occurring in the permanent magnet to escape to the outside of the laminated core and alleviating stress occurring in the resin.

[0007] Furthermore, Patent Document 2 discloses a method in which the surface of a permanent magnet is covered with an insulating nonwoven fabric, and the thermal expansion and contraction of the permanent magnet is alleviated by the nonwoven fabric deforming in the thickness direction, thereby preventing cracks from occurring in the resin. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2017-22886 A (paragraph 0036, Figure 11) [Patent Document 2] JP 2019-140773 A (paragraph 0024, Figure 3) Summary of the Invention [Problem to be solved by the invention]

[0009] However, while the method of relieving stress on the resin is an effective means of suppressing cracks, the rotor described in Patent Document 1 has the problem of requiring a special tool to move the magnets to the rotor ends. Also, the rotor described in Patent Document 2 has the problem of requiring a process to provide clearance for the nonwoven fabric and to evenly attach the nonwoven fabric that covers the magnets.

[0010] The present application has been made to solve the above-mentioned problems, and aims to provide a highly reliable rotating electric rotor that efficiently relieves stress on the resin and has high crack resistance within the magnet slots under heat cycle environments, as well as a manufacturing method thereof. [Means for solving the problem]

[0011] The rotor of the rotating electric machine disclosed in the present application comprises a rotor core having slots formed along the outer circumferential direction, permanent magnets disposed in the slots and fixed with resin, and stress relaxation layers formed on the surfaces of the permanent magnets and in which a portion of the resin is modified. the stress relaxation layer contains a long-chain hydrocarbon-based material and has a lower elastic modulus than the resin other than the stress relaxation layer, and is provided between the permanent magnet and the resin other than the stress relaxation layer to relieve stress that occurs in the resin other than the stress relaxation layer under a heat cycle environment. It is characterized by:

[0012] The method for manufacturing a rotor for a rotating electric machine disclosed in the present application is characterized by including the steps of forming a coating layer on the surface of a permanent magnet, inserting the permanent magnet into a slot provided in a rotor core, injecting resin between the slot and the permanent magnet and performing a heat treatment to fix the permanent magnet in the slot, and forming a stress relaxation layer in which a portion of the resin is modified by the coating layer. [Effects of the Invention]

[0013] The rotor for a rotating electric machine disclosed in the present application can efficiently introduce a stress relaxation layer onto the magnet surface without using special tools or securing extra clearance, and can also suppress the occurrence of cracks in the resin under heat cycle environments. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a plan view showing the configuration of a rotor of a rotating electric machine according to a first embodiment. [Figure 2] 3 is a partially enlarged cross-sectional view of a magnet slot portion illustrating the configuration of the rotor of the rotating electric machine according to the first embodiment. FIG. [Figure 3] 2 is a perspective view showing the configuration of permanent magnets in the rotor of the rotating electric machine according to the first embodiment. FIG. [Figure 4] 4 is a cross-sectional view showing changes in magnet slots before and after heat treatment of permanent magnets in the rotor of the rotating electric machine according to the first embodiment. FIG. [Figure 5] FIG. 4 is a perspective view showing another configuration of the permanent magnet in the rotor of the rotating electric machine according to the first embodiment. [Figure 6]4 is a flowchart showing the procedure of manufacturing steps in the method for manufacturing a rotor for a rotating electric machine according to the first embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] Embodiment 1 Preferred embodiments of the rotor for a rotating electric machine according to the present invention will be described below with reference to the drawings. Fig. 1 is a plan view showing the configuration of a rotor 100 for a rotating electric machine according to embodiment 1 of the present invention. Fig. 2 is a cross-sectional view taken along the line AA in Fig. 1. Fig. 3 is a perspective view showing the configuration of permanent magnets 3 provided in rotor 100 for a rotating electric machine.

[0016] As shown in FIGS. 1 and 2 , the rotor 100 of the rotating electric machine according to the first embodiment includes a rotor core 1 and permanent magnets 3 embedded in magnet slots 2 provided in the rotor core 1. A shaft slot 4 is provided in the center of the rotor core 1. A plurality of magnet slots 2 are provided along the circumferential direction of the rotor core 1. While FIG. 1 illustrates a four-pole rotor in which the number of magnet slots 2 is four and each permanent magnet 3 is embedded in the magnet slot 2, the number of poles of the rotor is not particularly limited. Furthermore, the magnet slots 2 may be provided with a protrusion-like structure for defining the position of the magnet or a flux barrier for preventing leakage magnetic flux. While FIG. 1 illustrates a rectangular shape, the shape of the magnet slots 2 is not particularly limited.

[0017] As shown in FIG. 3(a), the permanent magnet 3 is typically rectangular and is surface-treated with plating or epoxy resin (not shown). In this embodiment, as shown in FIG. 3(b), a coating layer 6 is applied to the upper surface of the surface treatment layer before the permanent magnet 3 is inserted into the magnet slot 2. The coating layer 6 preferably covers all six sides of the rectangular permanent magnet 3, i.e., the wide front and back sides, the narrow vertical sides, and the wide horizontal sides, but this is not limitative. From the perspective of ease of insertion, the coating layer 6 may cover at least eight vertices of the rectangular parallelepiped, rather than all six sides, as shown in FIG. 3(c). The coating layer 6 may be made of a liquid resin or oil.

[0018] The permanent magnets 3 are placed in the magnet slots 2. A magnet fixing resin 5 is filled between the rotor core 1 and the coating layer 6. The magnet fixing resin 5 should be liquid when filled and harden when the rotor is in use to fix the permanent magnets 3, and a thermosetting resin such as an epoxy resin can be used.

[0019] There are no particular limitations on the method for filling the magnet fixing resin 5, and any method known in the art can be used. Examples include a method of pouring the resin directly into the magnet slot 2 from the top, or a method of pouring the resin into a mold with a pouring port while applying pressure.

[0020] After filling, the magnet fixing resin 5 is heated to harden it. There are no particular restrictions on the conditions for the heat treatment of the magnet fixing resin 5, but for example, the resin is heated at 120°C for two hours so that the rotor core 1 and the permanent magnets 3 can be bonded and fixed.

[0021] 4A and 4B are cross-sectional views showing the changes in magnet slots 2 before and after heat treatment in rotor 100 of a rotating electric machine according to embodiment 1, with Fig. 4A showing the state before heat treatment and Fig. 4B showing the state after heat treatment. As shown in Figs. 4A and 4B, magnet fixing resin 5 and coating layer 6 mix or react with each other and harden near the magnet surface, forming stress relaxation layer 7.

[0022] The stress relaxation layer 7 has a composition based on the composition of the magnet fixing resin 5, with the components of the coating layer 6 incorporated into it. The coating layer 6 has a long-chain hydrocarbon chemical structure, which has the effect of modifying and plasticizing the magnet fixing resin 5. As a result, the stress relaxation layer 7 exhibits a lower elastic modulus than the magnet fixing resin 5.

[0023] As described above, the rotor 100 of the rotating electric machine according to the first embodiment is composed of a rotor core 1 laminated with circular electromagnetic steel plates, magnet slots 2 penetrating the rotor core 1 in the axial direction, permanent magnets 3 inserted into the magnet slots 2, and a resin part consisting of magnet fixing resin 5 that fixes the permanent magnets 3. By providing a stress relaxation layer 7 on the surface of the permanent magnets 3, the stress that occurs in the resin part due to heat cycles is relaxed by the stress relaxation layer, making it possible to prevent the occurrence of cracks.

[0024] The materials used in rotor 100 of the rotating electric machine according to the first embodiment will be described below. The rotor core 1 is not particularly limited and can be obtained by molding a steel sheet laminate made by laminating electromagnetic steel sheets, a dust core made of soft magnetic metal powder such as iron, iron-silicon alloy, or iron-carbon alloy, or a magnetic powder in which soft magnetic metal oxide powder is coated with a resin binder such as silicone resin, or a high-density dust core. The molding method is not particularly limited and includes methods such as cutting out the material or laminating electromagnetic steel sheets pressed into the desired shape. Among these, a rotor core 1 obtained by molding a steel sheet laminate made by laminating silicon steel sheets is preferred. In particular, from the viewpoint of preventing eddy current loss, a rotor core 1 obtained by molding a steel sheet laminate made by laminating silicon steel sheets with an insulating film formed on the surface is more preferred. The thickness of the silicon steel sheets is not particularly limited, but is generally 0.2 mm to 0.5 mm.

[0025] Examples of permanent magnet 3 include rare earth magnets, ferrite magnets, and alnico magnets, with rare earth magnets being preferred due to their ability to produce high output. Examples of rare earth magnets include neodymium-iron-boron and samarium-iron-nitrogen magnets. Among these, neodymium-iron-boron sintered magnets are preferred due to their superior magnetic performance. Neodymium-iron-boron sintered magnets may also be used to strengthen the coercive force of the grain boundaries by replacing only the neodymium at the grain boundaries with dysprosium or terbium using a diffusion method that diffuses dysprosium, terbium, or other elements along the interfaces (grain boundaries) between crystals. Surface treatments include plating with zinc, chromium, nickel, tin, gold, silver, rhodium, chromium-zinc, or the like, or coating with epoxy resin, polyimide resin, polyamide resin, fluororesin, or the like.

[0026] The permanent magnet 3 can be one type selected from various magnets, or a combination of multiple magnets can be used to obtain the desired motor characteristics of the rotating electric machine. The permanent magnet 3 embedded in the magnet slot 2 can be a single permanent magnet 3 pre-formed into a predetermined shape, but from the perspective of reducing eddy currents and temperature, it is also possible to use a permanent magnet 3 divided into multiple pieces, or to use a permanent magnet 3 that is joined together into a single piece (3a, 3b, 3c) (see Figure 5). A permanent magnet 3 with slits can also be used.

[0027] The magnet fixing resin 5 is preferably a thermosetting resin so that it can fill the gaps between the rotor core 1 and the permanent magnets 3. Examples of thermosetting resins include epoxy resin, acrylic resin, phenolic resin, and silicone resin. These resins can be used alone or in combination of two or more, but among them, epoxy resins that exhibit suitable miscibility and reactivity with the coating layer 6 for forming the stress relaxation layer 7 are particularly preferred.

[0028] Examples of the coating layer 6 are not particularly limited as long as they are mixed with the magnet fixing resin 5 and react upon heat treatment, and include epoxy resin, phenol resin, polyamide resin, silicone resin, or a mixture of two or more of these. Among these, particularly preferred are those having a long-chain hydrocarbon structure in the molecule, such as epoxidized soybean oil, epoxidized linseed oil, epoxidized fatty acid isobutyl in which unsaturated fatty acid esters have been epoxidized, epoxidized fatty acid 2-ethylhexyl, alicyclic epoxies such as 4,5-epoxycyclohexane-1,2-dicarboxylate di-2-ethylhexyl, 4,5-epoxycyclohexane-1,2-dicarboxylate di(9,10-epoxystearyl), and silanes such as 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacrylsilane, methyltriethoxy ... Examples of the modified silicone resin include amino-modified, epoxy-modified, carboxy-modified, and phenol-modified silicone resins. The modified silicone resin may be modified with amino, epoxy, carboxy or phenol at the side chain, one end, both ends or both ends of the side chain.

[0029] Furthermore, fats and oils having no reactive groups can also be used for the coating layer 6, and examples of the aliphatic dibasic acid include bis-2-ethylhexyl adipate, bis-isononyl adipate, bis-isodecyl adipate, bis-2-ethylhexyl azelaate, and bis-2-ethylhexyl sebacate, phthalate esters such as di-2-ethylhexyl phthalate, trimet esters such as tri-2-ethylhexyl phthalate, and phosphate esters such as tributyl phosphate and tris-2-ethylhexyl phosphate. These fats and oils may be used alone or in combination of two or more.

[0030] The rotor 100 of the rotating electric machine according to the first embodiment, which is manufactured as described above, can be used in various environments. For example, a rotating electric machine used in a cold region may be exposed to an environment of about -40°C. However, the rotor 100 of the rotating electric machine according to the first embodiment can be stably used even in a low-temperature environment because the permanent magnets 3 can be adhesively fixed in the magnet slots 2 without causing cracks in the resin. Furthermore, the operating temperature range of a rotating electric machine is usually high, at 150°C or higher, due to temperature rises in components (e.g., rotor core, permanent magnets), eddy currents, etc. However, the rotor 100 of the rotating electric machine according to the first embodiment can be used even in a high-temperature environment because the permanent magnets 3 can be adhesively fixed in the magnet slots 2 without causing cracks in the resin.

[0031] Examples are shown below, but the present invention is not limited to the following examples as long as they do not depart from the gist of the present invention.

[0032] Example 1 FIG. 6 is a flowchart showing the procedure of the manufacturing steps in the method for manufacturing rotor 100 for the rotating electric machine according to the first embodiment.

[0033] First, a rotor core 1 (diameter 140 mm, height 40 mm) with magnet slots was fabricated by laminating silicon steel sheets (0.3 mm) with insulating films formed on their surfaces and mechanically crimping them (step S601). Four magnet slots 2, each 45 mm wide and 8 mm long, were provided as shown in Figure 1.

[0034] Next, an acid anhydride curing epoxy resin with a viscosity of 2 to 3 Pa·s at 60°C was prepared as magnet fixing resin 5 for fixing the magnet (step S602). This epoxy resin can be cured by leaving it to stand in a 120°C environment for 2 hours, and after curing, its glass transition temperature is 160°C to 170°C and its flexural modulus is 15 to 20 GPa.

[0035] Next, a liquid resin, epoxidized linseed oil, was applied to the six surfaces of a rectangular parallelepiped (42 mm x 7.5 mm x 38 mm) neodymium-iron-boron sintered permanent magnet 3 with a zinc-plated surface in a non-dripping amount as a coating layer 6 (step S603).

[0036] Next, after preheating the rotor core 1 to 80° C., the permanent magnets 3 coated with epoxidized linseed oil were inserted into the magnet slots 2 (step S604).

[0037] Next, acid anhydride curing epoxy resin is poured into the magnet slots 2 so as to be flush with the upper surface of the rotor core 1 (step S605).

[0038] Finally, a heat treatment was performed at 120° C. for 2 hours to complete the sample 1 that would become the rotor 100 of the rotating electrical machine.

[0039] Example 2 In the above-mentioned Sample 1, Sample 2 was created by applying epoxidized linseed oil, a liquid resin, to eight vertices of the magnet as a coating layer 6, as shown in Figure 3(c). Note that the configuration of this rotor 100 for a rotating electric machine is the same as that of Sample 1 described above, except for the locations where the coating layer 6 is applied.

[0040] Example 3 Sample 3 was prepared by changing the coating layer 6 from epoxidized linseed oil, which is a liquid resin, to epoxidized fatty acid isobutyl, which is a liquid resin of a fatty acid ester system, in Sample 1 described above. Note that the configuration of this rotor 100 for a rotating electric machine other than the type of coating layer 6 is the same as that of Sample 1 described above.

[0041] Example 4 Sample 4 was prepared by changing the coating layer 6 from the liquid resin epoxidized linseed oil to a liquid resin silane-based 3-glycidoxypropylmethyldiethoxysilane in Sample 1. The configuration of the rotor 100 of this rotating electric machine other than the type of coating layer 6 is the same as that of Sample 1.

[0042] Example 5 Sample 5 was prepared by changing the coating layer 6 from the liquid resin epoxidized linseed oil in Sample 1 to a liquid resin, amine-modified silicone resin, in which both ends of a modified silicone resin-based polysiloxane are amine-modified. The rotor 100 for this rotating electric machine has the same configuration as Sample 1, except for the type of coating layer 6.

[0043] Example 6 Sample 6 was prepared by changing the coating layer 6 from epoxidized linseed oil, which is a liquid resin, to bis-2-ethylhexyl adipate, which is an aliphatic dibasic acid-based oil, in Sample 1. The configuration of this rotor 100 for a rotating electric machine, other than the type of coating layer 6, is the same as that of Sample 1.

[0044] Example 7 In Sample 1, the permanent magnet was divided into three pieces (14 mm x 7.5 mm x 38 mm), and all six sides of each piece were coated with epoxidized linseed oil as a coating layer 6. The magnets were then inserted into the magnet slots 2 in a row (see Figure 5) to create Sample 7. When coated with epoxidized linseed oil, no adhesive was needed to bond the divided magnets together, and the magnets could be inserted into the designated positions. Normally, adhesive is used to temporarily secure the divided magnets in place to increase the accuracy of the magnet insertion position. In this case, it was confirmed that the divided magnets could be temporarily secured using only the coating layer. Note that the configuration of this rotating electric machine rotor 100 is the same as that of Sample 1 described above, except that the permanent magnet 3 is divided into three pieces.

[0045] (Comparative Example 1) For comparison, Sample 8 was created by removing the coating layer 6 from the surface of the permanent magnet 3 of the above-mentioned Sample 1. The rotor of this rotating electric machine has the same configuration as Sample 1 except that it does not have a coating layer.

[0046] The formation of the stress relaxation layer and resistance to heat cycles were confirmed using Samples 1 to 7 of Examples 1 to 7 and Sample 8 of Comparative Example 1. The stress relaxation layer was formed as follows. Samples 1 to 8 were cut along the AA cross section in FIG. 1, and the surface condition of the permanent magnet 3 was observed. Samples 1 to 7 showed discoloration in the area corresponding to the stress relaxation layer, and palpation with a needle indicated elasticity with respect to the magnet fixing resin part.

[0047] In samples 1, 2, and 7, epoxidized linseed oil, a liquid resin, was used as the coating layer. Epoxidized linseed oil has multiple epoxy groups and multiple hydrocarbon groups with seven carbon atoms in its molecular skeleton. It was found that magnet fixing resin 5 reacts with the epoxy groups of epoxidized linseed oil used as coating layer 6, and the hydrocarbon groups impart plasticity to the reaction product.

[0048] In sample 3, epoxidized fatty acid isobutyl, a liquid resin, was used as the coating layer 6. Epoxidized fatty acid isobutyl has an epoxy group and multiple hydrocarbon groups with seven carbon atoms in its molecular skeleton. It was found that the magnet fixing resin 5 reacts with the epoxy group of the epoxidized fatty acid isobutyl used as the coating layer 6, and the hydrocarbon group imparts plasticity to the reaction product.

[0049] In sample 4, the coating layer 6 was made from a liquid resin, 3-glycidoxypropylmethyldiethoxysilane, a silane-based compound. 3-glycidoxypropylmethyldiethoxysilane is known for its use as a silane coupling agent. 3-glycidoxypropylmethyldiethoxysilane has an epoxy group in its molecular skeleton and a linear molecular structure with seven carbon atoms and one silicon atom. It was found that the magnet fixing resin 5 reacted with the epoxy group of 3-glycidoxypropylmethyldiethoxysilane used as the coating layer, and that the linear chemical structure consisting of carbon and silicon imparted plasticity to the reaction product.

[0050] Sample 5 used a liquid resin for coating layer 6, an amine-modified silicone resin in which both ends of a modified silicone resin-based polysiloxane were amine-modified. Amine-modified silicone resin has an amino group in its molecular skeleton that reacts with epoxy resin, and a polysiloxane structure. It was found that magnet fixing resin 5 reacts with the amino group of the amine-modified silicone resin used for coating layer 6, and the polysiloxane skeleton imparts plasticity to the reaction product.

[0051] In sample 6, bis-2-ethylhexyl adipate was used as the oil for the coating layer 6. Bis-2-ethylhexyl adipate has 22 carbon atoms and has ethylhexyl groups at both ends of the molecule. It was found that when the magnet fixing resin 5 was mixed with the bis-2-ethylhexyl adipate used as the coating layer 6, the reaction product was plasticized.

[0052] On the other hand, in Sample 8, discoloration and change in elasticity, as in Samples 1 to 7, were not observed at the interface between the permanent magnet 3 and the magnet fixing resin 5.

[0053] Next, crack resistance was evaluated using the above-mentioned Samples 1 to 8. For the test, the rotor of the rotating electric machine produced was placed in a heat cycle test chamber and left for 200 cycles under conditions of -40°C to 160°C, after which the rotor's appearance was checked for the presence or absence of cracks. No cracks were observed around the magnet fixing resin in Samples 1 to 7, but minute cracks were confirmed around the magnet fixing resin in Sample 8.

[0054] From the above results, it was found that the occurrence of cracks in the magnet fixing resin can be suppressed by applying a coating layer 6 to the surface of the permanent magnet 3 and providing a stress relief layer 7, which is formed by heat-treating the magnet fixing resin 5 that fixes the coating layer 6 and the permanent magnet 3 in the magnet slot 2.

[0055] As described above, rotor 100 for a rotating electric machine according to the first embodiment includes rotor core 1 having magnet slots 2 formed along the outer circumferential direction, permanent magnets 3 disposed in magnet slots 2 and fixed with magnet fixing resin 5, and a stress relief layer formed on the surface of permanent magnet 3, with a portion of magnet fixing resin 5 modified. Furthermore, a manufacturing method for a rotor for a rotating electric machine according to the first embodiment includes the steps of forming coating layer 6 containing a long-chain hydrocarbon material on the surface of permanent magnet 3, inserting permanent magnet 3 into magnet slot 2 formed in rotor core 1, and injecting magnet fixing resin 5 between magnet slot 2 and permanent magnet 3 and performing a heat treatment to fix permanent magnet 3 in magnet slot 2, and forming stress relief layer 7 with a portion of magnet fixing resin 5 modified by coating layer 6. This allows for efficient introduction of the stress relief layer on the magnet surface. Furthermore, a highly reliable rotor for a rotating electric machine can be provided that is capable of suppressing cracking in the magnet fixing resin under a heat cycle environment and firmly adhering and fixing permanent magnets.

[0056] Although various exemplary embodiments are described in this application, the various features, aspects, and functions described in the embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless modifications not illustrated are contemplated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, and even cases where at least one component is extracted and combined with other components. [Explanation of symbols]

[0057] 1 rotor core, 2 magnet slot, 3 permanent magnet, 5 magnet fixing resin, 6 coating layer, 6 coating layer, 7 stress relaxation layer, 100 rotor of a rotating electric machine.

Claims

1. a rotor core having slots formed along the outer periphery; a permanent magnet disposed in the slot and fixed with resin; a stress relaxation layer formed on the surface of the permanent magnet and in which a part of the resin is modified; Equipped with A rotor for a rotating electric machine, characterized in that the stress relaxation layer contains a long-chain hydrocarbon-based material and has a lower elastic modulus than the resin other than the stress relaxation layer, is provided between the permanent magnet and the resin other than the stress relaxation layer, and is provided to relieve stress that occurs in the resin other than the stress relaxation layer under a heat cycle environment.

2. The permanent magnet has a coating layer on its surface, 2. The rotor for a rotating electric machine according to claim 1, wherein the stress relaxation layer has a composition based on the composition of the resin and incorporating components of the coating layer.

3. forming a coating layer on the surface of the permanent magnet; Inserting the permanent magnets into slots provided in a rotor core; a step of injecting a resin between the slot and the permanent magnet and performing a heat treatment to fix the permanent magnet in the slot, and forming a stress relaxation layer in which a part of the resin is modified by the coating layer; A method for manufacturing a rotor for a rotating electric machine, comprising:

4. 4. The method for manufacturing a rotor for a rotating electric machine according to claim 3, wherein the stress relaxation layer has a lower modulus of elasticity than the resin.

5. 5. The method for manufacturing a rotor for a rotating electric machine according to claim 4, wherein the coating layer contains a long-chain hydrocarbon material.

6. 6. The method for manufacturing a rotor for a rotating electric machine according to claim 3, wherein the coating layer is formed by applying a liquid resin.

7. 6. The method for manufacturing a rotor for a rotating electric machine according to claim 3, wherein the coating layer is formed by applying oil.

8. 7. The method for manufacturing a rotor for a rotating electric machine according to claim 6, wherein the stress relaxation layer is formed by modifying the coating layer through a reaction between the coating layer and the liquid resin.

9. 8. The method for manufacturing a rotor for a rotating electric machine according to claim 7, wherein the stress relaxation layer is formed by mixing the coating layer with the grease to modify the coating layer.

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