Motor rotor and method for manufacturing motor rotor

Abstract

The motor rotor (50) includes an inner sleeve (51), a cylindrical permanent magnet (52) covering the outer peripheral surface (51d) of the inner sleeve (51), a cylindrical protective layer (55) covering the outer peripheral surface (52d) of the permanent magnet (52), an end ring (53) inserted into the inner sleeve (51) and in contact with the first magnet end surface (52a) of the permanent magnet (52), and an end ring (53) in contact with the second magnet end surface (52b) of the permanent magnet (52). The end rings (53, 54) are fixed to the inner sleeve (51) by an inner peripheral resin portion (56) formed between the ring inner peripheral surfaces (53c, 54c) and the outer peripheral surface (51d) of the inner sleeve (51).

Description

Technical Field

[0001] The present disclosure relates to a motor rotor and a method for manufacturing the motor rotor. Background Art

[0002] Patent Document 1 discloses a rotor with permanent magnets as a well-known technology related to motors. This rotor is a so-called motor rotor. The rotor in Patent Document 1 has multiple permanent magnets embedded in a resin material. This structure allows the permanent magnets to have a sufficient energy product, resulting in increased motor output.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 58-12562

[0004] Rotational balance is crucial for motor components. In particular, the higher the motor's rotational speed, the higher the required precision of rotational balance. One method for adjusting rotational balance involves, for example, first attaching a weight to the rotating body. Next, the weight attached to the rotating body is cut. This results in a more balanced mass distribution around the axis of rotation, improving rotational balance.

[0005] On the other hand, various performance requirements are placed on the motor depending on the external device to which the motor is applied. For example, the motor output may be required to be increased or decreased depending on the state of the external device. In this case, it is desirable to improve the responsiveness of the motor output so as to quickly respond to changes in the state of the external device. The responsiveness of the output is related to the mass of the rotor of the motor. In the method of using an adjustment weight to improve the rotational balance, the size of the weight is required to be such that the rotational balance can be adjusted. On the other hand, if the weight becomes larger, the mass of the weight increases. As a result, the mass of the rotor increases, which may deteriorate the stability of the rotation. Summary of the Invention

[0006] The present disclosure describes a motor rotor and a method of manufacturing a motor rotor that can reduce mass.

[0007] A motor rotor, one embodiment of the present disclosure, includes a shaft; a cylindrical magnet covering the outer circumference of the shaft; a cylindrical protective layer covering the outer circumference of the magnet; and an annular end ring inserted through the shaft and in contact with the end surface of the magnet. The end ring is secured to the shaft by an inner circumferential resin portion formed between the inner circumferential surface of the end ring and the outer circumferential surface of the shaft.

[0008] According to the motor rotor and the method for manufacturing the motor rotor disclosed herein, it is possible to reduce mass. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a cross-sectional view showing a supercharger including the motor rotor of the present disclosure.

[0010] Figure 2 It is a perspective view showing the structure of a motor rotor.

[0011] Figure 3 (a) Figure 3 (b) and Figure 3 (c) is a diagram showing the steps of a method for manufacturing a motor rotor.

[0012] Figure 4 (a) Figure 4 (b) and Figure 4 (c) is a diagram showing the steps of a method for manufacturing a motor rotor.

[0013] Figure 5 (a) and Figure 5 (b) is a diagram showing the steps of a method for manufacturing a motor rotor. DETAILED DESCRIPTION

[0014] A motor rotor, one embodiment of the present disclosure, includes a shaft; a cylindrical magnet covering the outer circumference of the shaft; a cylindrical protective layer covering the outer circumference of the magnet; and an annular end ring inserted through the shaft and in contact with the end surface of the magnet. The end ring is secured to the shaft by an inner circumferential resin portion formed between the inner circumferential surface of the end ring and the outer circumferential surface of the shaft.

[0015] The end rings of the motor rotor can be used as weights for adjusting rotational balance. When adjusting rotational balance, the greater the distance from the rotation axis to the mass point, the greater the effect of adjusting the rotational balance obtained when adjusting the mass. In other words, the closer the distance from the rotation axis to the mass point, the smaller the effect of adjusting the rotational balance obtained when adjusting the mass. The end rings of the motor rotor are fixed to the shaft body via the inner peripheral resin portion. According to this structure, the end ring with a large mass is arranged in a portion with a high effect of adjusting the rotational balance due to being away from the rotation axis. The inner peripheral resin portion with a small mass is arranged in a portion with a low effect of adjusting the rotational balance due to being close to the rotation axis. As a result, the adjustment margin of the end ring as a weight can be reduced compared to a structure in which the end ring is directly fixed to the shaft body. As a result, lightweight end rings can be used. By adopting the inner peripheral resin portion, the motor rotor can be made lightweight. Therefore, the mass of the motor rotor can be reduced.

[0016] In one embodiment, the end ring may include an adjustment mark.

[0017] In one embodiment, the density of the material constituting the end ring may be higher than the density of the material constituting the inner peripheral resin portion. According to this configuration, the motor rotor can be made lighter.

[0018] In one embodiment, the length of the protective layer along the axis of the shaft may be longer than the length of the magnet along the axis of the shaft. With this configuration, the protective layer can protect the magnet. Furthermore, the end ring can also be protected by the protective layer.

[0019] In one embodiment, the entire inner end surface of the end ring may face the end surface of the magnet. According to this configuration, the end ring can be arranged at a position away from the rotation axis.

[0020] In one embodiment, an outer peripheral resin portion may be provided between the outer peripheral surface of the end ring and the inner peripheral surface of the protective layer. According to this configuration, the end ring can be protected by the protective layer.

[0021] In one embodiment, the outer peripheral resin portion may include a first portion provided between the outer peripheral surface of the end ring and the inner peripheral surface of the protective layer, and a second portion extending from the first portion along the outer end surface of the end ring.

[0022] Another method for manufacturing a motor rotor according to the present disclosure includes the following steps: placing a shaft in a mold; placing a cylindrical magnet covering the outer circumference of the shaft and an annular end ring in the mold, the end ring being inserted through the shaft and contacting the end surface of the magnet; and filling the space between the outer circumference of the shaft and the inner circumference of the magnet, and between the outer circumference of the shaft and the inner circumference of the end ring, with an uncured resin material. This manufacturing method allows for the production of a motor rotor that achieves both high rotational balance and lightweight performance. Furthermore, the magnet and end ring can be formed in a single filling step.

[0023] The motor rotor of the present disclosure will be described with reference to the accompanying drawings. Figure 1 This figure shows a cross section of supercharger 1, including the rotation axis H. Supercharger 1 is a variable-capacity supercharger equipped with the motor rotor disclosed herein. In the following description, the term "axial direction" refers to the axial direction of the rotating shaft 2, described later. "Radial direction" refers to the radial direction of the rotating shaft 2. "Circumferential direction" refers to the circumferential direction of the rotating shaft 2.

[0024] The supercharger 1 is applied to an internal combustion engine mounted on a vehicle or the like. Figure 1 As shown, the supercharger 1 includes a turbine 3 and a compressor 4. The turbine 3 includes a turbine housing 31 and a turbine wheel 32. The turbine wheel 32 is housed in the turbine housing 31. The turbine housing 31 has a vortex flow path 33 disposed around the turbine wheel 32. The vortex flow path 33 extends circumferentially. The compressor 4 includes a compressor housing 41 and a compressor wheel 42. The compressor wheel 42 is housed in the compressor housing 41. The compressor housing 41 has a vortex flow path 43 disposed around the compressor wheel 42. The vortex flow path 43 extends circumferentially.

[0025] The turbine impeller 32 is provided at one end of the rotating shaft 2. The compressor impeller 42 is provided at the other end of the rotating shaft 2. The bearing housing 21 is provided between the turbine housing 31 and the compressor housing 41. The rotating shaft 2 is rotatably supported by the bearing housing 21 via the bearings 22. The rotating shaft 2, the turbine impeller 32, and the compressor impeller 42 rotate around the rotation axis H as an integrated rotating body 23.

[0026] The turbine housing 31 is provided with an exhaust gas inlet and an exhaust gas outlet 31a. Exhaust gas from the internal combustion engine flows into the turbine housing 31 through the exhaust gas inlet. The exhaust gas flowing into the turbine housing 31 flows through the vortex flow path 33 and flows into the turbine impeller 32. The exhaust gas flowing into the turbine impeller 32 rotates the turbine impeller 32. The exhaust gas that rotates the turbine impeller 32 flows out of the turbine housing 31 through the exhaust gas outlet 31a.

[0027] The compressor housing 41 is provided with an intake port 41a and an exhaust port. When the turbine impeller 32 rotates, the compressor impeller 42 rotates via the rotating shaft 2. The rotating compressor impeller 42 draws in external air through the intake port 41a. The drawn-in air is compressed while passing through the compressor impeller 42 and the vortex flow path 43. The compressed air is discharged from the exhaust port. The compressed air discharged from the exhaust port is supplied to the internal combustion engine.

[0028] The supercharger 1 includes an electric motor 5. When the torque of the rotating shaft 2 is insufficient, such as during vehicle acceleration, the electric motor 5 applies torque to the rotating shaft 2 to compensate for the insufficient torque. The electric motor 5 is, for example, a brushless AC motor. The electric motor 5 includes a motor rotor 50 as a rotor and a motor stator 60 as a stator. The vehicle's battery can be used as a drive source for the electric motor 5. When the vehicle decelerates, the electric motor 5 can also generate regenerative power using the rotational power of the rotating body 23. The electric motor 5 has the characteristic of being able to handle high-speed rotation of the rotating shaft 2. The so-called high-speed rotation can be, for example, approximately 100,000 to 200,000 rpm.

[0029] The motor rotor 50 is axially positioned between the bearing 22 and the compressor impeller 42. The motor rotor 50 is fixed to the rotating shaft 2 and can rotate together with the rotating shaft 2. The motor stator 60 is housed in the bearing housing 21. The motor stator 60 circumferentially surrounds the motor rotor 50. The motor stator 60 includes multiple coils and multiple cores. Supplying current to the coils generates a magnetic field. The magnetic field generated by the motor stator 60 exerts a circumferential force on the motor rotor 50, thereby imparting torque to the rotating shaft 2.

[0030] Reference Figure 2Next, the motor rotor 50 will be described. The motor rotor 50 includes an inner sleeve 51 , permanent magnets 52 , end rings 53 , 54 , a protective layer 55 , an inner peripheral resin portion 56 , and an outer peripheral resin portion 57 .

[0031] The inner sleeve 51 forms a shaft body together with the rotating shaft 2. The inner sleeve 51 has a large diameter portion 511 having a slightly larger diameter. The large diameter portion 511 is located in the center of the axial direction. As a material for the inner sleeve 51, for example, a steel material such as SCM435H can also be used.

[0032] A cylindrical permanent magnet 52 is provided around the large diameter portion 511. Grooves may be formed at equal intervals along the circumferential direction on the outer peripheral surface of the permanent magnet 52, and the grooves extend in the axial direction. The axial length of the permanent magnet 52 is substantially the same as the axial length of the large diameter portion 511. As the permanent magnet 52, for example, a neodymium magnet (Nd-Fe-B) and a samarium cobalt magnet may be used. The permanent magnet 52 is covered by an inner peripheral resin portion 56 and an outer peripheral resin portion 57. As a result, the permanent magnet 52 is protected from the influence of the external environment.

[0033] The protective layer 55 is a cylindrical component. The protective layer 55 is sometimes also called an "armor ring". The cylindrical protective layer 55 is provided around the permanent magnet 52. The protective layer 55 prevents fragments from scattering radially when the permanent magnet 52 is damaged. The protective layer 55 suppresses the deformation of the permanent magnet 52 and reduces the possibility of damage to the permanent magnet 52. Therefore, the protective layer 55 is required to have a certain degree of rigidity. The axial length of the protective layer 55 is longer than the axial length of the permanent magnet 52. The axial length of the protective layer 55 is longer than the axial length of the large diameter portion 511. As a material for the protective layer 55, a metal material or a resin material can be used. As a metal material, non-magnetic metals such as titanium (for example, Ti-6Al-4V) can be listed. As a resin material, CFRP (carbon fiber reinforced plastic) can also be listed.

[0034] End rings 53 and 54 sandwich the permanent magnet 52 in the direction of the rotation axis H. The length of the structure comprising end rings 53, 54, and permanent magnet 52 is approximately the same as the length of protective layer 55. End rings 53 and 54 are annular. End ring 53 has an inward end surface 53a (inner end surface), an outward end surface 53b (outer end surface), an inner circumferential surface 53c, and an outer circumferential surface 53d. End ring 54 has an inward end surface 54a (inner end surface), an outward end surface 54b (outer end surface), an inner circumferential surface 54c, and an outer circumferential surface 54d.

[0035] The density of the material of the end rings 53 and 54 is greater than the density of the material of the inner peripheral resin portion 56, which will be described later. As long as this density relationship is satisfied, the materials of the end rings 53, 54, and inner peripheral resin portion 56 can be appropriately selected. For example, the materials of the end rings 53 and 54 can be non-magnetic metals such as SUS, thermosetting resins, and thermoplastic resins.

[0036] The annular end ring 53 contacts the first magnet end face 52a of the permanent magnet 52. More specifically, the inward end face 53a of the end ring 53 contacts the first magnet end face 52a of the permanent magnet 52. This "contact" does not necessarily need to be fixed. The inward end face 53a may also be bonded to the first magnet end face 52a. The inward end face 53a may also only contact the first magnet end face 52a. Figure 2 In the example shown, the diameter of the ring outer surface 53d is the same as the diameter of the magnet outer surface 52d of the permanent magnet 52. The ring outer surface 53d and the magnet outer surface 52d are coplanar. The diameter of the ring inner surface 53c is larger than the diameter of the magnet inner surface 52c. The ring inner surface 53c and the magnet inner surface 52c are not coplanar. There is a step between the ring inner surface 53c and the magnet inner surface 52c. With this structure, the ring inner surface 53c does not directly contact the sleeve outer surface 51d. There is a gap between the ring inner surface 53c and the sleeve outer surface 51d. The gap between the ring inner surface 53c and the sleeve outer surface 51d is filled with the inner peripheral resin portion 56.

[0037] The relationship between the permanent magnet 52 and the end ring 53 is not limited to the relationship described above. The inner portion of the inward end surface 53a may be closer to the rotation axis H than the magnet inner circumferential surface 52c of the permanent magnet 52. The diameter of the ring inner circumferential surface 53c may be smaller than the diameter of the magnet inner circumferential surface 52c of the permanent magnet 52. The outer portion of the inward end surface 53a may be further away from the rotation axis H than the magnet outer circumferential surface 52d of the permanent magnet 52. The diameter of the ring outer circumferential surface 53d may be larger than the diameter of the magnet outer circumferential surface 52d of the permanent magnet 52.

[0038] The inner peripheral resin portion 56 is bonded to the ring inner peripheral surface 53c. The end ring 53 is fixed to the inner sleeve 51 through the inner peripheral resin portion 56. The outer peripheral resin portion 57 is bonded to the ring outer peripheral surface 53d. The end ring 53 is fixed to the protective layer 55 through the outer peripheral resin portion 57. The outer peripheral resin portion 57 is also bonded to a portion of the outer peripheral side of the outer end surface 53b. Figure 2 In the illustrated example, the inner peripheral side of the outward end surface 53b is an exposed surface. No resin portion or the like is provided on the inner peripheral side of the outward end surface 53b.

[0039] The end ring 54 contacts the second magnet end surface 52b of the permanent magnet 52. The inward end surface 54a of the end ring 54 contacts the second magnet end surface 52b of the permanent magnet 52. The detailed structure of the end ring 54 is the same as that of the end ring 53. Therefore, a detailed description of the end ring 54 is omitted.

[0040] A tiny gap exists between the inner sleeve 51 and the permanent magnet 52. An inner circumferential resin portion 56 is formed in this gap. As a result, the sleeve outer circumferential surface 51d of the inner sleeve 51 is covered with the inner circumferential resin portion 56. The magnet inner circumferential surface 52c is covered with the inner circumferential resin portion 56. The ring inner circumferential surface 53c of the end ring 53 is also covered with the inner circumferential resin portion 56. The ring inner circumferential surface 54c of the end ring 54 is also covered with the inner circumferential resin portion 56. The inner circumferential resin portion 56 includes a portion 56s1, a portion 56s2, and a portion 56s3. Portion 56s1 is sandwiched between the sleeve outer circumferential surface 51d and the magnet inner circumferential surface 52c. Portion 56s2 is sandwiched between the sleeve outer circumferential surface 51d and the ring inner circumferential surface 53c. Portion 56s3 is sandwiched between the sleeve outer circumferential surface 51d and the ring inner circumferential surface 54c. The first end surface 56a of the inner peripheral resin portion 56 may be coplanar with the outward end surface 53b of the end ring 53. The second end surface 56b of the inner peripheral resin portion 56 may protrude from the outward end surface 54b of the end ring 54. In other words, a step may be formed between the second end surface 56b and the outward end surface 54b.

[0041] There is a tiny gap between the permanent magnet 52 and the protective layer 55. A peripheral resin portion 57 is formed in the gap between the permanent magnet 52 and the protective layer 55. As a result, the magnet outer peripheral surface 52d of the permanent magnet 52 is covered with the peripheral resin portion 57. The protective layer inner peripheral surface 55c is covered with the peripheral resin portion 57. The inner peripheral side of the second protective layer end surface 55b of the protective layer 55 is also covered with the peripheral resin portion 57. The ring outer peripheral surface 53d of the end ring 53 is also covered with the peripheral resin portion 57. The ring outer peripheral surface 54d of the end ring 54 is also covered with the peripheral resin portion 57. The outer peripheral portion of the outward end surface 53b of the end ring 53 is also covered with the peripheral resin portion 57. The outer peripheral portion of the outward end surface 54b of the end ring 54 is also covered with the peripheral resin portion 57. The peripheral resin portion 57 includes a portion 57s1, a portion 57s2 (first portion), and a portion 57s3 (first portion). Portion 57s1 is sandwiched between the magnet outer peripheral surface 52d and the protective layer inner peripheral surface 55c. Portion 57s2 is sandwiched between the ring outer peripheral surface 53d and the protective layer inner peripheral surface 55c. Portion 57s3 is sandwiched between the ring outer peripheral surface 54d and the protective layer inner peripheral surface 55c. The peripheral resin portion 57 further includes portion 57s4 (second portion). Portion 57s4 protrudes from the outward end surface 53b of the end ring 53 on the first end surface side of the peripheral resin portion 57. Portion 57s4 covers a portion of the outward end surface 53b. The peripheral resin portion 57 further includes portion 57s5 and portion 57s6. Portion 57s5 protrudes from the outward end surface 54b of the end ring 54 on the second end surface side of the peripheral resin portion 57. Portion 57s5 covers a portion of the outward end surface 54b of the end ring 54. The portion 57s6 also protrudes from the outward end surface 54b of the end ring 54 on the second end surface side of the outer peripheral resin portion 57. The portion 57s6 covers a portion of the second protective layer end surface 55b of the protective layer 55.

[0042] The inner sleeve 51, permanent magnets 52, protective layer 55, end rings 53, and end rings 54 are integrally connected via an inner peripheral resin portion 56 and an outer peripheral resin portion 57. The inner peripheral resin portion 56 transmits torque from the permanent magnets 52 to the inner sleeve 51. The outer peripheral resin portion 57 transmits torque from the permanent magnets 52 to the protective layer 55. In the supercharger 1, the torque transmitted from the permanent magnets 52 to the inner sleeve 51 is, for example, approximately 0.5 Nm. The torque transmitted from the permanent magnets 52 to the protective layer 55 is also, for example, approximately 0.5 Nm.

[0043] The inner and outer resin portions 56 and 57 can be made of thermosetting resins, thermoplastic resins, and the like. The inner and outer resin portions 56 and 57 can be made of thermoplastic resins and epoxy resins, which are thermosetting resins. Furthermore, the inner and outer resin portions 56 and 57 can be made of liquid crystal polymer (LCP), which is a thermoplastic resin. According to the inventors' experiments, LCP has higher fluidity during injection molding than thermoplastic resins, making it a preferred material for the inner and outer resin portions 56 and 57. LCP is more readily available than plastic resins, making it a preferred material for the inner and outer resin portions 56 and 57. Thermoplastic resins have superior heat resistance, rigidity, and environmental resistance to LCP, making them a preferred material for the inner and outer resin portions 56 and 57. Epoxy resin is a preferred material for the inner and outer resin portions 56 and 57 due to its adhesive properties.

[0044] The material of the inner peripheral resin portion 56 needs to satisfy a predetermined relationship with the material of the end ring 53 . The density of the material of the inner peripheral resin portion 56 is lower than the density of the material of the end ring 53 .

[0045] The manufacturing method of the motor rotor 50 is described. Figure 3 As shown in (a), prepare the mold 91. Next, arrange the inner sleeve 51 inside the mold 91. Next, arrange the end ring 53, the permanent magnet 52 and the end ring 54 in order inside the mold 91 (process S1). When arranging the end ring 53, the permanent magnet 52 and the end ring 54, a gap is provided between the inner sleeve 51 and the permanent magnet 52. A gap is also provided between the inner sleeve 51 and the end ring 53. A gap is also provided between the inner sleeve 51 and the end ring 54. It is also possible to arrange the end ring 53, the permanent magnet 52 and the end ring 53 after the inner sleeve 51 is arranged. In addition, it is also possible to arrange the inner sleeve 51 after the end ring 53, the permanent magnet 52 and the end ring 53 are arranged. Next, as Figure 3 As shown in (b), the cover 92 is mounted (step S2). The cover 92 is provided with a hole 92a. The hole 92a is provided in the cover 92 in order to fill the hole 92a with the uncured resin material 56s that will become the inner peripheral resin portion 56.

[0046] Next, if Figure 3As shown in (c), uncured resin material 56s is filled (process S3). When the uncured resin material 56s is filled, the mold 91 and the cover 92 are preheated to a predetermined temperature. Therefore, the filled resin material 56s is cured over time. When the curing is completed, a subassembly 50s (SUB ASSY) is obtained. The subassembly 50s is formed by integrating the inner sleeve 51, the permanent magnet 52, the end ring 53 and the end ring 54 through the inner peripheral resin portion 56. Moreover, after removing the cover 92, the subassembly 50s is removed from the mold 91 (refer to Figure 4 (a), (step S4)).

[0047] Next, if Figure 4 As shown in (b), the subassembly 50s is placed on another mold 93 (step S5). Next, a protective layer 55 is placed on the mold 93 where the subassembly 50s is placed. Figure 4 As shown in (c), the cover 94 is configured (process S6). When the cover 94 is configured, a gap is formed between the permanent magnet 52 and the protective layer 55. A gap is also formed between the end ring 53 and the protective layer 55. A gap is also formed between the outer peripheral side of the outward end surface 53b of the end ring 53 on the inner side and the mold 93. The inner peripheral side of the outward end surface 53b is in contact with the mold 93. A gap is also formed between the outer peripheral side of the outward end surface 54b of the end ring 54 on the near front side and the cover 94. The gap is connected to the hole 94a provided in the cover 94. The gap functions as a resin storage portion. The inner peripheral side of the second protective layer end surface 55b included in the protective layer 55 does not contact the cover 94. The outer peripheral side of the second protective layer end surface 55b included in the protective layer 55 is in contact with the cover 94.

[0048] Next, if Figure 5 As shown in (a), uncured resin material 57s is filled (step S7). As in step S3, mold 93 and cover 94 are preheated to a predetermined temperature. Therefore, the filled resin material 57s cures over time. When curing is complete, the motor rotor 50 is obtained (step S8). The motor rotor 50 is formed by integrating the inner sleeve 51, permanent magnets 52, end rings 53, end rings 54, and protective layer 55 via the inner peripheral resin portion 56 and the outer peripheral resin portion 57.

[0049] The inventors aim to practically implement an electric compressor for a two-stage supercharging system that achieves transient responsiveness and wide operating range. They also aim to practically implement an electric assist turbine that regenerates excess turbine output during high load conditions. These electric compressors and electric assist turbines require specific rotational speeds based on aerodynamic conditions. For example, the electric compressor requires a rotational speed of approximately 100,000 rpm, while the electric assist turbine requires a rotational speed of approximately 200,000 rpm.

[0050] Electric vehicles have stringent requirements for high efficiency, low noise, and space saving. To meet these demands, surface permanent magnetic (SPM) motors are the preferred choice. Generally, interior permanent magnet (IPM) motors are advantageous for achieving high rotational speeds. IPM motors can be multi-polarized and multi-slotted. For example, motors for hybrid vehicles are commercialized using multi-polarization and multi-slot concepts. However, multi-polarization and multi-slot concepts cannot be adopted for electric compressors and electric auxiliary turbines.

[0051] A major challenge for ultra-high-speed SPM motors is preventing magnet scattering. In particular, small motors incorporate cylindrical magnets inserted into the shaft. Furthermore, these motors employ a protective layer (armor ring) around the outer circumference of the cylindrical magnets to prevent scattering. These structures prevent magnet breakage in small motors. The armor rings must be lightweight and high-strength. To minimize impact on magnetic performance, they must be non-magnetic. Furthermore, the thickness of the armor rings must be reduced.

[0052] Based on the above technical background, the inventors developed a motor rotor that can be used in electric compressors and electric auxiliary turbines. Furthermore, through several technical developments, they succeeded in achieving an economical motor rotor with significantly reduced inertia. To enable application at even higher speeds and achieve superior controllability, the inventors conducted research to further reduce the inertia of the motor rotor.

[0053] The motor rotor 50 is obtained based on the above results. The end rings 53 and 54 of the motor rotor 50 can be used as weights for adjusting rotational balance. When adjusting rotational balance, the greater the distance from the rotation axis H to the weights used for adjusting rotational balance, the greater the effect of adjusting rotational balance when adjusting the mass of the weights. Conversely, the closer the distance from the rotation axis H to the weights used for adjusting rotational balance, the smaller the effect of adjusting rotational balance when adjusting the mass of the weights. The end rings 53 and 54 of the motor rotor 50 are fixed to the inner sleeve 51 via the inner circumferential resin portion 56. Therefore, the end rings 53 and 54, with their larger mass, are positioned away from the rotation axis H, where they have a higher effect on adjusting rotational balance. The inner circumferential resin portion 56, with its smaller mass, is positioned closer to the rotation axis H, where it has a lower effect on adjusting rotational balance. As a result, the use of the inner circumferential resin portion 56 can achieve a lighter weight compared to a structure in which the end rings 53 and 54 are directly fixed to the inner sleeve 51. Therefore, the mass of the motor rotor 50 can be reduced.

[0054] The end rings 53 and 54 can be used as machining allowances (balance areas) in the rotational balance correction work performed after the assembly work. As a function of the balance area, the effect is higher the further it is located on the outer peripheral side. The inventors thought that it is less necessary for the end rings 53 and 54 to be disc-shaped, as long as they are annular. The shape of the end rings 53 and 54 is set to be annular. Moreover, the end rings 53 and 54 are not pressed in, but are integrated with the permanent magnet 52 by injection molding of resin material. In this way, in the end rings, the part close to the rotation axis H is replaced by resin material. As a result, the weight is reduced corresponding to the volume replaced by the resin material from the end rings and the density difference between the material of the end rings and the resin material. As a result, a lighter motor rotor 50 can be obtained. In addition, the process of pressing the end rings 53 and 54 in the subsequent process can be omitted. Therefore, it is more economical.

[0055] The end ring 53 and the end ring 54 are balance areas. Therefore, the end ring 53 and the end ring 54 may also include adjustment marks. The so-called adjustment marks are traces of balance adjustment. The so-called adjustment marks are, for example, depressions and protrusions provided on the end ring 53 and the end ring 54. The depressions and protrusions are produced by cutting a part of the end ring 53 and the end ring 54 in order to reduce the weight during the balance adjustment operation. In addition, the so-called adjustment marks are, for example, heat marks. Heat marks are produced by the heat generated during the processing for adjusting the weight. In addition, the so-called adjustment marks are, for example, the curvature of the processing groove caused by additional grinding of the parts and the discontinuity of the pattern of the processing groove. In addition, the so-called adjustment marks are the parts of the rotational imbalance around the rotation axis when the end ring 53 and the end ring 54 are rotated as a single unit.

[0056] The present disclosure can be implemented in various ways based on the above-mentioned embodiments and various changes and improvements based on the knowledge of those skilled in the art. In addition, the technical matters described in the above-mentioned embodiments can also be used to form modified examples. The structures of the various embodiments can also be appropriately combined.

[0057] In the above embodiment, the motor rotor 50 is described as an example in which it is applied to the electric motor 5 of the supercharger 1. The motor rotor 50 can also be applied to an electric compressor.

[0058] Description of Reference Numerals

[0059] 1...supercharger; 2...rotating shaft; 3...turbine; 4...compressor; 5...motor; 21...bearing housing; 22...bearing; 23...rotating body; 31...turbine housing; 32...turbine impeller; 33...vortex flow path; 41...compressor housing; 42...compressor impeller; 43...vortex flow path; 50...motor rotor; 50s...subassembly; 51...inner sleeve (shaft); 51d...sleeve outer circumference; 52...permanent magnet (magnet); 52c...magnet inner circumference; 52d...magnet outer circumference; 53, 54...end ring; 53c, 54c...ring inner circumference; 53d, 54d...ring outer circumference; 55...protective layer; 56...inner circumferential resin portion; 57...outer circumferential resin portion; 60...motor stator; H...rotating axis.

Claims

1. A motor rotor, characterized in that: have: Axis; a cylindrical magnet covering the outer circumference of the shaft; a cylindrical protective layer covering the outer peripheral surface of the magnet; and an end ring, which is annular and is passed through the shaft and contacts the end surface of the magnet; The end ring is fixed to the shaft body by an inner peripheral resin portion formed between the inner peripheral surface of the end ring and the outer peripheral surface of the shaft body. The entire inner end surface of the end ring faces the end surface of the magnet.

2. The motor rotor according to claim 1, wherein: The end ring includes an adjustment mark.

3. The motor rotor according to claim 1 or 2, characterized in that: The density of the material constituting the end ring is higher than the density of the material constituting the inner peripheral resin portion.

4. The motor rotor according to claim 1 or 2, characterized in that: A length of the protective layer along the axis of the shaft is longer than a length of the magnet along the axis of the shaft.

5. A motor rotor, characterized in that: have: Axis; a cylindrical magnet covering the outer circumference of the shaft; a cylindrical protective layer covering the outer peripheral surface of the magnet; and an end ring, which is annular and is passed through the shaft and contacts the end surface of the magnet; The end ring is fixed to the shaft body by an inner peripheral resin portion formed between the inner peripheral surface of the end ring and the outer peripheral surface of the shaft body. An outer peripheral resin portion is provided between the outer peripheral surface of the end ring and the inner peripheral surface of the protective layer. The outer peripheral resin portion includes a first portion provided between an outer peripheral surface of the end ring and an inner peripheral surface of the protection layer, and a second portion extending from the first portion along an outer end surface of the end ring.

6. A method for manufacturing a motor rotor, characterized in that: Has the following processes: a step of arranging a shaft body and a cylindrical magnet covering an outer peripheral surface of the shaft body in a mold, and arranging an end ring in a ring shape so as to be inserted through the shaft body and to be in contact with an end surface of the magnet; and The process of filling uncured resin material between the outer peripheral surface of the shaft body and the inner peripheral surface of the magnet and between the outer peripheral surface of the shaft body and the inner peripheral surface of the end ring, The entire inner end surface of the end ring faces the end surface of the magnet.

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