Rotor sleeve, rotary electrical machine rotor, and manufacturing method for rotary electrical machine rotor

Abstract

Provided is a rotor sleeve that is not readily affected by the operating conditions or installation conditions of a rotary electrical machine, and can allow a rotor to rotate stably. Also provided are a rotary electrical machine rotor and a manufacturing method for a rotary electrical machine rotor. This rotor sleeve (1) is used in a rotary electrical machine rotor (10) having a permanent magnet (2), a shaft (3) provided on an end section side of the permanent magnet (2), and the rotor sleeve (1), which has the permanent magnet (2) and the shaft (3) positioned in the interior thereof, and the rotor sleeve (1) is characterized by comprising: a metal first cylindrical section (4) that is a cylindrical shape in which the inner diameter and the outer diameter are each constant, and has the permanent magnet (2) positioned in the interior thereof; and a fiber-reinforced plastic second cylindrical section (5) that is a cylindrical shape in which the inner diameter is constant, and has the first cylindrical section (4) positioned in the interior thereof, wherein the thickness of the second cylindrical section (5) is greater than the thickness of the first cylindrical section (4) across the entirety from one end to the other end in the length direction of the first cylindrical section (4) and the second cylindrical section (5).

Description

Rotor sleeve, rotor for rotating electric machine, and method of manufacturing rotor for rotating electric machine

[0001] The present invention relates to a rotor sleeve, a rotor for a rotating electric machine, and a method for manufacturing a rotor for a rotating electric machine.

[0002] A rotating electric machine includes a rotor around an axis, the rotor having a rotating shaft and a permanent magnet, and a cylindrical member (also called a sleeve) is installed around the permanent magnet to prevent the permanent magnet from scattering during rotation.

[0003] In the following Patent Document 1, a first cylindrical member and a second cylindrical member are provided around a magnetic body, which is a permanent magnet, and a shaft member, the first cylindrical member being made of, for example, stainless steel, and the second cylindrical member being made of, for example, a titanium alloy or a carbon fiber reinforced material. The second cylindrical member is overlapped on the radially outer side of the first cylindrical member, and the thickness of the second cylindrical member is thinner than the thickness of the cylindrical main body of the first cylindrical member.

[0004] In addition, in the following Patent Document 2, a rotor includes a permanent magnet, a metal protective sleeve, and a CFRP shrink ring. The permanent magnet is fitted onto the outer periphery of a rotating shaft and has a truncated conical cylindrical shape with tapered inner and outer peripheries over the entire axial length. The protective sleeve has an inner periphery tapered to match the outer periphery of the permanent magnet, and an outer periphery with a tapered or cylindrical surface. The shrink ring has a protective sleeve attached to its inner periphery, and the shape of the inner periphery is tapered or cylindrical to match the outer periphery of the protective sleeve.

[0005] JP 2022-38525 A Patent No. 4172066 A

[0006] As disclosed in the above-mentioned Patent Documents 1 and 2, there is a technique of applying fiber reinforced plastic such as carbon fiber reinforced plastic to the rotor sleeve in order to reduce the weight and improve the strength of the rotor.

[0007] However, in Patent Document 1, the first cylindrical member has low strength, the second cylindrical member has high strength, and the first cylindrical member is thicker than the second cylindrical member. Therefore, when the rotating electric machine is used at ultra-high speeds for a long period of time accompanied by heat cycles, creep deformation occurs in the first cylindrical member of the rotor disclosed in Patent Document 1, and the tension force for holding the permanent magnets inside is reduced.

[0008] Furthermore, in the example of Patent Document 2 in which the CFRP shrink ring is tapered (see FIG. 1), the strength of the thinner side (i.e., the larger diameter side of the rotating shaft) is low, so the compressive force of the shrink ring on the magnet is weak. Therefore, if the rotating electric machine is used at ultra-high speeds for a long period of time accompanied by heat cycles, there is a risk that the rotor will break starting from the thinner side of the shrink ring.

[0009] Furthermore, in the example of Patent Document 2 in which the shrink ring is cylindrical (FIG. 3), similar to the tapered example of FIG. 1, the inner circumferential surface of the metal protective sleeve, the inner and outer circumferential surfaces of the permanent magnet, and the outer circumferential surface of the rotating shaft are all tapered, and each component has a shape with a different diameter along its length. Therefore, each component has a different coefficient of linear expansion within it. Therefore, when a rotating electric machine is used at ultra-high speeds for a long period of time with heat cycles, misalignment is likely to occur at the mating portions of the components. For example, when a rotating electric machine rotates at high speeds due to temperature changes, the thicker side of the component may not deform, while the thinner side may expand in diameter.

[0010] Furthermore, tapered components such as those described in Patent Document 2 require tapering for production, which requires time and effort and costs. Furthermore, not only does it require adjusting the taper angle of each component, but misalignment of the angles can prevent the components from fitting together properly, resulting in an unbalanced assembled rotor. Therefore, the rotor described in Patent Document 2 is difficult to apply to rotating electrical machines that rotate at ultra-high speeds.

[0011] In rotating electrical machines that operate at ultra-high speeds while undergoing long-term heat cycles ranging from below room temperature to above room temperature, there is a high possibility of creep deformation, especially in sleeves that have dual components arranged in them. As a result, the tension on the magnets provided by the sleeve is lost, causing the problem of rotor rotational balance being lost.

[0012] The present invention has been made in consideration of the above circumstances, and aims to provide a rotor sleeve, a rotor for a rotating electric machine, and a method for manufacturing a rotor for a rotating electric machine, which are less susceptible to the operating conditions and installation conditions of a rotating electric machine and are capable of rotating the rotor stably.

[0013] In order to solve the above problems, the rotor sleeve, the rotor for a rotating electric machine, and the method for manufacturing the rotor for a rotating electric machine of the present invention employ the following measures: That is, the rotor sleeve of the present invention is a rotor sleeve for use in a rotor for a rotating electric machine having a permanent magnet, a shaft provided on an end of the permanent magnet, and a rotor sleeve in which the permanent magnet and the shaft are disposed, the rotor sleeve comprising: a first cylindrical portion made of a metal other than a shape-memory material, the first cylindrical portion having a constant inner diameter and a constant outer diameter, the permanent magnet being disposed inside the first cylindrical portion so that the outer surface of the permanent magnet contacts the inner surface of the first cylindrical portion; and a second cylindrical portion made of a fiber-reinforced plastic, the second cylindrical portion having a constant inner diameter, the first cylindrical portion being disposed inside the first cylindrical portion so that the outer surface of the first cylindrical portion contacts the inner surface of the second cylindrical portion, the second cylindrical portion having a thickness greater than the thickness of the first cylindrical portion over the entire length of the first and second cylindrical portions from one end to the other, and the first cylindrical portion being disposed in a press-fit state within the second cylindrical portion.

[0014] The rotor of the rotating electric machine according to the present invention comprises the rotor sleeve described above, a permanent magnet arranged inside the first cylindrical portion of the rotor sleeve, and a shaft arranged inside the first cylindrical portion of the rotor sleeve and provided on the end side of the permanent magnet, wherein the permanent magnet is arranged in a pressed-in state inside the first cylindrical portion.

[0015] In the above invention, the axial length of the first cylindrical portion and the second cylindrical portion may be longer than the axial length of the permanent magnet.

[0016] A reference example of the present invention provides a method for manufacturing a rotor sleeve for use in a rotor of a rotating electric machine having a permanent magnet, a shaft provided on the end side of the permanent magnet, and a rotor sleeve in which the permanent magnet and the shaft are arranged, and is characterized in that it includes a first press-fitting step in which a cylindrical first cylindrical portion made of metal is pressed into a cylindrical second cylindrical portion made of fiber-reinforced plastic, the thickness of the second cylindrical portion being greater than the thickness of the first cylindrical portion, and before the first press-fitting step, the outer diameter of the first cylindrical portion being greater than the inner diameter of the second cylindrical portion, and the first press-fitting step positions the first cylindrical portion inside the second cylindrical portion so that the outer surface of the first cylindrical portion is in contact with the inner surface of the second cylindrical portion.

[0017] The method for manufacturing a rotor for a rotating electric machine according to the present invention is a method for manufacturing a rotor for a rotating electric machine having a permanent magnet, a shaft provided on an end side of the permanent magnet, and a rotor sleeve in which the permanent magnet and the shaft are disposed, and comprises a first press-fitting process of press-fitting a cylindrical first cylindrical portion made of metal into a cylindrical second cylindrical portion made of fiber-reinforced plastic, and a second press-fitting process of press-fitting the permanent magnet into the first cylindrical portion while it is disposed inside the second cylindrical portion, wherein the thickness of the second cylindrical portion is greater than the thickness of the first cylindrical portion, and before the first press-fitting process, the outer diameter of the first cylindrical portion is greater than the inner diameter of the second cylindrical portion, and the first press-fitting process positions the first cylindrical portion inside the second cylindrical portion so that the outer surface of the first cylindrical portion contacts the inner surface of the second cylindrical portion, and before the second press-fitting process, the outer diameter of the permanent magnet is greater than the inner diameter of the first cylindrical portion while it is disposed inside the second cylindrical portion, and the second press-fitting process positions the permanent magnet inside the first cylindrical portion so that the outer surface of the permanent magnet contacts the inner surface of the first cylindrical portion.

[0018] In the above invention, the ratio (δ2 / δ1) of the second interference (δ2), which is the difference between the outer diameter of the first cylindrical portion and the inner diameter of the second cylindrical portion before the first press-fitting step, to the first interference (δ1), which is the difference between the outer diameter of the permanent magnet before the second press-fitting step and the inner diameter of the first cylindrical portion when disposed inside the second cylindrical portion, is 0.8 or more and 1.6 or less.

[0019] In the above invention, the first interference (δ1) and the second interference (δ2) may have the same value.

[0020] According to the present invention, the rotor can be rotated stably without being affected by the operating conditions and installation conditions of the rotating electrical machine.

[0021] 1 is a longitudinal sectional view showing a rotor according to an embodiment of the present invention; FIG. 2 is a flowchart showing a method for manufacturing a rotor according to an embodiment of the present invention; FIG. 3 is a schematic diagram showing each step of a method for manufacturing a rotor according to an embodiment of the present invention; FIG. 4 is a graph showing the relationship between the inner diameter change rate of a first cylindrical portion and interference δ2 / interference δ1;

[0022] 1, a rotor 10 for a rotating electric machine according to one embodiment of the present invention includes a rotor sleeve (hereinafter referred to as "sleeve") 1, a permanent magnet 2, and a shaft 3 provided on the end side of the permanent magnet 2. The rotor 10 is a component installed in a rotating electric machine, and is installed together with a stator inside a housing of the rotating electric machine.

[0023] The permanent magnet 2 is cylindrical and is disposed inside the sleeve 1 so that its outer circumferential surface is in contact with the inner circumferential surface of the sleeve 1. The permanent magnet 2 and the sleeve 1 are disposed coaxially. The length of the permanent magnet 2 is shorter than the length of the sleeve 1, and the permanent magnet 2 is disposed approximately in the center of the sleeve 1, with the ends of the permanent magnet 2 located inside the sleeve 1.

[0024] The shaft 3 is cylindrical and is disposed inside the sleeve 1 so that its outer circumferential surface contacts the inner circumferential surface of the sleeve 1. The shaft 3 is disposed coaxially with the permanent magnet 2 and the sleeve 1. The rotor 10 is provided with two shafts 3, each disposed at one end of the permanent magnet 2, and the ends of the shafts 3 and the permanent magnet 2 contact each other inside the sleeve 1.

[0025] The sleeve 1 includes a first cylindrical portion 4 made of metal and a second cylindrical portion 5 made of fiber-reinforced plastic, with the first cylindrical portion 4 disposed inside the second cylindrical portion 5. The axial lengths of the first cylindrical portion 4 and the second cylindrical portion 5 are longer than the axial length of the permanent magnet 2.

[0026] The first cylindrical portion 4 is made of a metal such as stainless steel and has a cylindrical shape with a constant inner and outer diameter. This allows for uniform tension along the length, unlike a tapered metal cylindrical member. The permanent magnet 2 is placed inside the first cylindrical portion 4 so that the outer surface of the permanent magnet 2 is in contact with the inner surface of the first cylindrical portion 4.

[0027] The second cylindrical portion 5 is made of fiber-reinforced plastic, such as CFRP (carbon fiber reinforced plastic), and has a cylindrical shape with constant inner and outer diameters. This allows for uniform tension along the length, unlike when a fiber-reinforced plastic cylindrical member has a tapered shape. The first cylindrical portion 4 is disposed inside the second cylindrical portion 5 so that the outer surface of the first cylindrical portion 4 contacts the inner surface of the second cylindrical portion 5.

[0028] The thickness of the second cylindrical portion 5 is greater than the thickness of the first cylindrical portion 4 throughout the entire length of the first and second cylindrical portions 4 and 5, from one end to the other. This allows the tensioning force of the fiber-reinforced plastic second cylindrical portion 5 to reliably fix the first cylindrical portion 4 to the interior. Unlike this embodiment, if the fiber-reinforced plastic cylindrical portion located on the outside is thinner than the metal cylindrical portion located on the inside, the tensioning force is weaker, and creep deformation is likely to occur under conditions such as when the rotating electrical machine is used at ultra-high speeds for long periods of time accompanied by heat cycles. In contrast, this embodiment can suppress creep deformation even under such conditions.

[0029] 2 and 3, a method for manufacturing the rotor sleeve 1 and a method for manufacturing the rotor 10 will be described. First, to manufacture the sleeve 1, the first cylindrical portion 4 made of metal and the second cylindrical portion 5 made of fiber-reinforced plastic are separately manufactured (step S11).

[0030] 3A, the cylindrical first cylindrical portion 4 made of metal is press-fitted into the cylindrical second cylindrical portion 5 made of fiber-reinforced plastic (first press-fitting step) (step S12). Specifically, a lubricant such as molybdenum disulfide lubricant is applied to the surface of the first cylindrical portion 4, and the first cylindrical portion 4 is press-fitted into the second cylindrical portion 5 by a press.

[0031] Before the first press-fitting step, the outer diameter of the first cylindrical portion 4 disposed on the inside is larger than the inner diameter of the second cylindrical portion 5 disposed on the outside. In other words, the first cylindrical portion 4 and the second cylindrical portion 5 are manufactured so as to have an interference δ2 (second interference) which is the difference between the outer diameter of the first cylindrical portion 4 and the inner diameter of the second cylindrical portion 5 before the first press-fitting step.

[0032] By the first press-fitting step, the first cylindrical portion 4 is disposed inside the second cylindrical portion 5 so that the outer surface of the first cylindrical portion 4 contacts the inner surface of the second cylindrical portion 5. The interference δ2 (second interference) is set to a value that allows the metal first cylindrical portion 4 to be appropriately press-fitted into the fiber-reinforced plastic second cylindrical portion 5. In this way, the sleeve 1 according to this embodiment is manufactured.

[0033] 3(B), the cylindrical permanent magnet 2 is press-fitted into the sleeve 1 manufactured above, i.e., into the first cylindrical portion 4 disposed inside the second cylindrical portion 5 (second press-fitting step) (step S13). Specifically, a lubricant such as molybdenum disulfide lubricant is applied to the surface of the permanent magnet 2, and the permanent magnet 2 is press-fitted into the first cylindrical portion 4 of the sleeve 1 by a press.

[0034] Before the second press-fitting step, the outer diameter of the permanent magnet 2 disposed on the inside is larger than the inner diameter of the first cylindrical portion 4 when disposed inside the second cylindrical portion 5. In other words, the permanent magnet 2, the first cylindrical portion 4, and the second cylindrical portion 5 are manufactured so as to have an interference δ1 (first interference), which is the difference between the outer diameter of the permanent magnet 2 before the second press-fitting step and the inner diameter of the first cylindrical portion 4 when disposed inside the second cylindrical portion 5.

[0035] By the second press-fitting step, the permanent magnet 2 is disposed inside the first cylindrical portion 4 so that the outer surface of the permanent magnet 2 contacts the inner surface of the first cylindrical portion 4. The interference δ1 (first interference) may be a value that is generally used when press-fitting a permanent magnet into a sleeve.

[0036] 3C, the cylindrical shaft 3 is press-fitted into the first cylindrical portion 4 of the sleeve 1 with the permanent magnet 2 disposed inside the first cylindrical portion 4 (step S14). The shaft 3 is press-fitted onto both ends of the permanent magnet 2. In this way, the rotor 10 according to this embodiment is manufactured.

[0037] Next, the interference set for each component for the above-mentioned press-fitting will be described. The ratio (δ2 / δ1) of the interference δ2, which is the difference between the outer diameter of the first cylindrical portion 4 and the inner diameter of the second cylindrical portion 5 before the first press-fitting step, to the interference δ1, which is the difference between the outer diameter of the permanent magnet 2 before the second press-fitting step and the inner diameter of the first cylindrical portion 4 when disposed inside the second cylindrical portion 5, is preferably 0.8 or more and 1.6 or less. In particular, it is even better if the values ​​of the interference δ1 and the interference δ2 are the same (δ2 / δ1 = 1.0). The reason for this is as follows.

[0038] After fabricating the sleeve 1 and the rotor 10, a creep test was performed on the rotor 10. The creep test was performed at 150°C for 72 hours. A plurality of values ​​were set for the wall thickness of the first cylindrical portion 4, and a plurality of values ​​were set for the interference δ1 and interference δ2, to fabricate a plurality of types of rotors 10, and a creep test was performed on each rotor 10. The permanent magnet 2 was then removed, and the inner diameter of the metallic first cylindrical portion 4 was measured. The amount of change in the inner diameter of the first cylindrical portion 4 before and after the creep test was calculated.

[0039] 4, regardless of the wall thickness of the first cylindrical portion 4 or the absolute values ​​of the interference δ1 and interference δ2, when the ratio of the interference δ2 to the interference δ1 (δ2 / δ1) was 0.8 to 1.6, the change in the inner diameter of the first cylindrical portion 4 before and after the creep test was relatively small. In particular, when the ratio of the interference δ2 to the interference δ1 (δ2 / δ1) was 1.0, the change in the inner diameter of the first cylindrical portion 4 before and after the creep test was smallest.

[0040] In other words, regardless of whether the creep test was performed or not, it can be said that the metallic first cylindrical portion 4 deformed within the elastic range without plastic deformation when the ratio of the interference δ2 to the interference δ1 (δ2 / δ1) was within the above-mentioned range. Therefore, even when the rotor 10 was used under severe conditions such as high temperatures, the tension force exerted by the sleeve 1 on the permanent magnet 2 could be maintained. On the other hand, when the ratio of the interference δ2 to the interference δ1 (δ2 / δ1) was less than 0.8 or more than 1.6, the change in the inner diameter of the first cylindrical portion 4 before and after the creep test was relatively large, which may result in a relatively low tension force exerted by the sleeve 1 on the permanent magnet 2.

[0041] 1: Rotor sleeve (sleeve) 2: Permanent magnet 3: Shaft 4: First cylindrical portion 5: Second cylindrical portion 10: Rotor

Claims

1. A rotor sleeve used in a rotor of a rotating electric machine having a permanent magnet, a shaft provided on the end side of the permanent magnet, and a rotor sleeve in which the permanent magnet and the shaft are placed, comprising: a first cylindrical portion made of metal excluding shape memory material, having a cylindrical shape with constant inner and outer diameters, with the permanent magnet placed inside so that the outer surface of the permanent magnet contacts the inner surface; and a second cylindrical portion made of fiber reinforced plastic, having a cylindrical shape with a constant inner diameter, with the first cylindrical portion placed inside so that the outer surface of the first cylindrical portion contacts the inner surface, wherein the thickness of the second cylindrical portion is greater than the thickness of the first cylindrical portion over the entire length of the first and second cylindrical portions from one end to the other, and wherein the first cylindrical portion is placed in a pressed-fit state inside the second cylindrical portion.

2. A rotor for a rotating electric machine comprising: a rotor sleeve as claimed in claim 1; a permanent magnet arranged inside the first cylindrical portion of the rotor sleeve; and a shaft arranged inside the first cylindrical portion of the rotor sleeve and provided on the end side of the permanent magnet, wherein the permanent magnet is arranged in a state of being pressed into the inside of the first cylindrical portion.

3. A rotor for a rotating electric machine according to claim 2, wherein the axial lengths of the first cylindrical portion and the second cylindrical portion are longer than the axial length of the permanent magnet.

4. A method for manufacturing a rotor for a rotating electric machine having a permanent magnet, a shaft provided on an end side of the permanent magnet, and a rotor sleeve in which the permanent magnet and the shaft are placed, comprising: a first press-fitting step of press-fitting a cylindrical first cylindrical portion made of metal into a cylindrical second cylindrical portion made of fiber-reinforced plastic; and a second press-fitting step of press-fitting the permanent magnet into the first cylindrical portion while it is placed inside the second cylindrical portion, wherein the thickness of the second cylindrical portion is greater than the thickness of the first cylindrical portion; before the first press-fitting step, the outer diameter of the first cylindrical portion is greater than the inner diameter of the second cylindrical portion; by the first press-fitting step, the first cylindrical portion is placed inside the second cylindrical portion so that the outer surface of the first cylindrical portion is in contact with the inner surface of the second cylindrical portion; before the second press-fitting step, the outer diameter of the permanent magnet is greater than the inner diameter of the first cylindrical portion while it is placed inside the second cylindrical portion; a ratio (δ2 / δ1) of a second interference (δ2) which is the difference between the outer diameter of the first cylindrical portion and the inner diameter of the second cylindrical portion before the first press-fitting step to a first interference (δ1) which is the difference between the outer diameter of the permanent magnet before the second press-fitting step and the inner diameter of the first cylindrical portion when the permanent magnet is disposed inside the second cylindrical portion is 0.8 or more and 1.6 or less.

5. A method for manufacturing a rotor for a rotating electrical machine according to claim 4, wherein the first interference (δ1) and the second interference (δ2) have the same value.

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