阅读说明：本技术 马达转子 (Motor rotor ) 是由 饭嶋海 杉浦光 佐佐木裕司 福井达哉 胜义仁 汤本良介 于 2020-03-24 设计创作，主要内容包括：马达转子具备：内套筒、配置于内套筒的周围的圆筒状的永磁铁、以及由填充于内套筒与永磁铁的间隙的树脂构成的树脂部,内套筒具有小径部,该小径部位于轴向上的与永磁铁的端部的内周面对置的位置,并且形成为比轴向上的与永磁铁的中央部的内周面对置的部位的直径小。(The motor rotor is provided with: the inner sleeve has a small diameter portion that is located at a position facing an inner peripheral surface of an end portion of the permanent magnet in the axial direction and that is formed to have a smaller diameter than a portion facing an inner peripheral surface of a central portion of the permanent magnet in the axial direction.)

1. A motor rotor is characterized in that,

the disclosed device is provided with: a shaft portion, a cylindrical magnet disposed around the shaft portion, and a resin portion made of resin filled in a gap between the shaft portion and the magnet,

the shaft portion has a small diameter portion that is located at a position facing an inner peripheral surface of an end portion of the magnet in the axial direction and that is formed to have a diameter smaller than a diameter of a portion facing an inner peripheral surface of a central portion of the magnet in the axial direction.

2. The motor rotor of claim 1,

a groove extending in a direction including a circumferential component is formed in an outer peripheral surface of the shaft portion.

3. The motor rotor according to claim 1 or 2,

the small diameter portion is a tapered portion formed to decrease in diameter as it is spaced apart from the central portion of the magnet in the axial direction.

4. The motor rotor according to claim 1 or 2,

the small diameter portion is formed to have a small diameter so as to have a step between portions facing the central portion of the magnet.

Technical Field

The present disclosure relates to a motor rotor.

Background

Conventionally, a motor rotor including a cylindrical magnet disposed around a shaft portion is known. As a method for manufacturing such a motor rotor, there is a method of bonding and fixing a cylindrical magnet to a shaft portion (see, for example, patent document 1).

Patent document 1: japanese patent laid-open publication No. 2016-

Patent document 2: japanese patent laid-open No. 2000-014062

Patent document 3: japanese patent laid-open No. 2005-198447.

Disclosure of Invention

As described above, according to the method of bonding and fixing the cylindrical magnet to the shaft portion, the shaft portion and the cylindrical magnet can be aligned well. However, in order to obtain a good adhesion state between the shaft portion and the cylindrical magnet, it is necessary to grind the inner peripheral surface of the cylindrical magnet to adjust the size and then adhere the cylindrical magnet to the shaft portion, which causes a troublesome grinding process. The present disclosure describes a motor rotor in which the shaft portion and the magnet can be aligned by a simple method.

A motor rotor according to one aspect of the present disclosure includes: the shaft portion has a small diameter portion that is formed to have a smaller diameter than a portion facing an inner peripheral surface of a central portion of the magnet in the axial direction, and that is located at a position facing the inner peripheral surface of an end portion of the magnet in the axial direction.

According to the motor rotor of the present disclosure, the shaft portion and the magnet can be aligned by a simple method.

Drawings

Fig. 1 is a sectional view showing an example of a supercharger to which a motor rotor according to an embodiment is applied.

Fig. 2 is a sectional view of a rotor of the motor.

FIG. 3 is a side view showing the inner sleeve and the permanent magnet.

FIG. 4 is a side view showing another mode of the inner sleeve and the permanent magnet.

Fig. 5 is a cross-sectional view showing an example of a state of a mold when a resin portion is formed by injection molding.

Fig. 6 is a sectional view showing a state where the inner sleeve and the permanent magnet are eccentric.

Detailed Description

A motor rotor according to one aspect of the present disclosure includes: the shaft portion has a small diameter portion that is formed to have a smaller diameter than a portion facing an inner peripheral surface of a central portion of the magnet in the axial direction, and that is located at a position facing the inner peripheral surface of an end portion of the magnet in the axial direction.

A groove extending in a direction including a circumferential component may be formed on an outer peripheral surface of the shaft portion. The small diameter portion may be a tapered portion formed to decrease in diameter as it is spaced from the central portion of the magnet in the axial direction. The small diameter portion may be formed to have a step difference between portions facing the central portion of the magnet.

A motor rotor according to an embodiment will be described with reference to the drawings. Fig. 1 is a sectional view of the supercharger 1 taken in a section including the rotation axis H. The supercharger 1 is a supercharger for a vehicle including the motor rotor of the embodiment. In the following description, the terms "axial direction", "radial direction", and "circumferential direction" refer to the axial direction, the radial direction, and the circumferential direction of the rotating shaft 14, respectively, which will be described later.

The supercharger 1 is applied to an internal combustion engine of a vehicle or the like. As shown in fig. 1, a supercharger 1 includes a turbine 2 and a compressor 3. The turbine 2 includes a turbine housing 4 and a turbine wheel 6 housed in the turbine housing 4. The turbine housing 4 has a scroll flow path 16 extending circumferentially around the turbine wheel 6. The compressor 3 includes a compressor housing 5 and a compressor impeller 7 housed in the compressor housing 5. The compressor housing 5 has a scroll flow path 17 extending in the circumferential direction around the compressor impeller 7.

The turbine impeller 6 is provided at one end of the rotary shaft 14, and the compressor impeller 7 is provided at the other end of the rotary shaft 14. A bearing housing 13 is provided between the turbine housing 4 and the compressor housing 5. The rotary shaft 14 is rotatably supported by the bearing housing 13 via a bearing 15, and the rotary shaft 14, the turbine impeller 6, and the compressor impeller 7 rotate around the rotation axis H as an integral rotary body 12.

The turbine housing 4 is provided with an exhaust gas inlet (not shown) and an exhaust gas outlet 10. Exhaust gas discharged from an internal combustion engine (not shown) flows into the turbine housing 4 through the exhaust gas inlet port. Thereafter, the exhaust gas flows into the turbine wheel 6 through the scroll flow path 16, and the turbine wheel 6 is rotated. Thereafter, the exhaust gas flows out of the turbine housing 4 through the exhaust gas outflow port 10.

The compressor housing 5 is provided with a suction port 9 and a discharge port (not shown). As described above, when the turbine impeller 6 rotates, the compressor impeller 7 rotates via the rotating shaft 14. The rotating compressor wheel 7 sucks in outside air through the suction port 9. The air is compressed by the compressor impeller 7 and the scroll flow path 17, and discharged from the discharge port. The compressed air discharged from the discharge port is supplied to the internal combustion engine.

The supercharger 1 is provided with an electric motor 21. For example, when the torque of the rotary shaft 14 is insufficient at the time of acceleration of the vehicle, the motor 21 applies torque to the rotary shaft 14 to compensate for the shortage. The motor 21 is, for example, a brushless dc motor. The electric motor 21 includes a motor rotor 25 as a rotating member and a motor stator 27 as a stationary member. As a drive source of the motor 21, a battery of the vehicle can be used. Further, the electric motor 21 can generate power by regenerating the rotational energy of the rotating body 12 when the vehicle is decelerated. The motor 21 has a characteristic of being capable of coping with high-speed rotation (for example, 10 to 20 ten thousand rpm) of the rotary shaft 14.

The motor rotor 25 is disposed between the bearing 15 and the compressor impeller 7 in the axial direction. The motor rotor 25 is fixed to the rotary shaft 14 and is rotatable together with the rotary shaft 14. The motor stator 27 is disposed so as to circumferentially surround the motor rotor 25 housed in the bearing housing 13. The motor stator 27 includes a plurality of coils and a core (not shown). When a current is supplied to the coils and a magnetic field is generated in the motor stator 27, a circumferential force acts on the permanent magnets 37 of the motor rotor 25 by the magnetic field, and as a result, a torque is applied to the rotary shaft 14.

Next, the motor rotor 25 will be described with reference to fig. 2. The motor rotor 25 is an assembly including the inner sleeve 31, the permanent magnet 37, the end rings 39 and 41, the protective layer 43, and the resin portion 50. The inner sleeve 31, the permanent magnet 37, the end rings 39 and 41, the protective layer 43, and the resin portion 50 are formed in a shape of a rotor having the rotation axis H as the center axis.

The inner sleeve 31 has a large diameter portion 33. The large-diameter portion 33 is provided with a slightly larger diameter at the axial center portion of the inner sleeve 31. The permanent magnet 37 is cylindrical and provided around the large diameter portion 33. The protective layer 43 is a cylindrical member, and may be referred to as a "guard ring" or the like. The protective layer 43 is cylindrical and provided around the permanent magnet 37. The protective layer 43 prevents fragments from scattering in the radial direction when the permanent magnet 37 is broken. In order to suppress deformation of the permanent magnet 37 and reduce the possibility of breakage of the permanent magnet 37, the protective layer 43 needs to have a certain degree of rigidity.

A slight gap exists between the inner sleeve 31 (shaft portion) and the permanent magnet 37. The gap is filled with resin by the resin material of the resin portion 50. The resin portion 50 is formed by injection molding or transfer molding, for example. The inner sleeve 31 and the permanent magnet 37 are integrally connected via the resin portion 50. Further, the torque transmission between the inner sleeve 31 and the permanent magnet 37 can be made through the resin portion 50. The torque transmitted by the supercharger 1 is, for example, about 0.5 Nm.

The permanent magnet 37 and the protective layer 43 may be coupled by filling the gap between the permanent magnet 37 and the protective layer 43 with resin. The end rings 39 and 41 may be connected to the inner sleeve 31 and the protective layer 43 via filled resin portions.

As described above, the motor rotor 25 is an integrated assembly. The rotating shaft 14 is inserted into a hollow portion of the inner sleeve 31 of the motor rotor 25, and the motor rotor 25 is fastened to the rotating shaft 14 together with the compressor impeller 7 by a nut 18 (see fig. 1).

As a material of the inner sleeve 31, for example, a steel material such as SCM435H can be used. As the material of the permanent magnets 37, for example, neodymium magnets (Nd-Fe-B), samarium-cobalt magnets, and the like can be used. As a material of the protective layer 43, a metal material or a resin material can be used. As the metal material, a non-magnetic metal such as titanium (for example, Ti-6Al-4V) can be used. As the resin material, CFRP (carbon fiber reinforced plastic) or the like can be used. As the material of the end rings 39 and 41, for example, a non-magnetic metal such as SUS, a thermosetting resin, a thermoplastic resin, or the like can be used.

As a material of the resin portion 50, thermosetting resin, thermoplastic resin, or the like can be used. More specifically, as the material of the resin portion 50, a phenol resin, an epoxy resin, or an LCP (liquid crystal polymer) as a thermosetting resin can be used. In addition, according to the test by the present inventors, LCP is preferable as the material of the resin portion 50 in view of its higher fluidity at the time of injection molding compared to the phenol resin. In addition, LCP is also preferable as the material of the resin portion 50, because it is relatively easy to obtain compared with phenol resin. On the other hand, a phenol resin is preferable as a material of the resin portion 50 because it is superior to LCP in heat resistance, rigidity, and environmental resistance. Epoxy resin is preferable as the material of the resin portion 50 because it has adhesiveness to the material itself.

Fig. 3 is a side view showing only the inner sleeve 31 and the permanent magnet 37 in the motor rotor 25. In fig. 3, the features described in the description are drawn exaggeratedly, and the sizes of the respective portions may not be the same as those in other drawings.

As shown in fig. 3, the inner peripheral surface 38 of the permanent magnet 37 is a cylindrical inner peripheral surface. Hereinafter, of the inner circumferential surfaces 38, the inner circumferential surface at the end portion of the permanent magnet 37 in the axial direction is referred to as an inner circumferential surface 38a, and the inner circumferential surface at the center portion of the permanent magnet 37 in the axial direction is referred to as an inner circumferential surface 38b. The inner sleeve 31 has a small diameter portion 61. The small diameter portion 61 is formed at a position facing the inner peripheral surface 38a in the radial direction. The small diameter portion 61 is formed smaller than the diameter of the central portion 63 of the inner sleeve 31. The central portion 63 is located at a position facing the inner peripheral surface 38b of the permanent magnet 37.

In the example of fig. 3, the small diameter portion 61 is a tapered portion 62a. The tapered portion 62a is formed to be tapered as it is spaced from the central portion 63 in the axial direction. The outer peripheral surface of the tapered portion 62a is a conical surface. The small diameter portion 61 is not limited to the tapered portion 62a. For example, as shown in fig. 4, the small diameter portion 61 may be a stepped small diameter portion 62b formed to have a step difference with the central portion 63. The outer peripheral surface of the stepped small diameter portion 62b is a cylindrical surface.

As shown in fig. 3, a groove 65 extending in a direction including a circumferential component is formed in the outer circumferential surface 31a of the inner sleeve 31. In the example of fig. 3, the groove 65 includes a circumferential groove 66a and a damask knurling groove 66b. The circumferential groove 66a extends in the circumferential direction on the outer circumferential surface 31a. The damask knurling groove 66b extends spirally in two directions crossing each other on the outer circumferential surface 31a. The groove 65 does not necessarily have to be provided with both the circumferential groove 66a and the silk-like knurled groove 66b, and may be provided with only one of them. Instead of the satin knurling groove 66b, a knurling groove formed of a spiral groove extending in one direction may be used.

Fig. 5 is a cross-sectional view showing an example of a state of the mold 70 when the resin portion 50 is formed by injection molding. As shown in fig. 5, the inner sleeve 31 and the permanent magnet 37 are accommodated in the mold 70. The permanent magnet 37 is disposed around the inner sleeve 31. A gap 69 exists between the inner sleeve 31 and the permanent magnet 37. When the molten resin 71 is injected from the left side of the mold 70 in the axial direction, the molten resin 71 flows to the right side in the gap 69 and fills the gap 69. The molten resin 71 is solidified to form the resin portion 50.

Here, when the molten resin 71 is introduced into the gap 69, the flow state of the molten resin 71 may be nonuniform in the circumferential direction. As shown in fig. 6, the molten resin 71 may be solidified in a state where the inner sleeve 31 and the permanent magnet 37 are eccentric. In this case, the resin may not be able to spread over the portion (reference numeral 73 in the figure) where the gap 69 is narrowed, and become defective. Further, the above defect may be an important factor for peeling off the resin portion 50.

On the other hand, as shown in fig. 3 and 4, the inner sleeve 31 has a small diameter portion 61. Thereby, the gap 69 is expanded in the radial direction at the position of the end of the permanent magnet 37, which is the entrance of the molten resin 71. According to this structure, the gap between the small-diameter portion 61 and the inner peripheral surface 38a is wide, and the injection speed of the molten resin 71 in this gap is relatively slow. Therefore, the molten resin 71 is easily distributed over the entire circumferential direction in the gap between the small diameter portion 61 and the inner circumferential surface 38a. The molten resin 71 flows in the axial direction over the entire circumferential direction, and fills the gap 69. By enlarging the entrance of molten resin 71 into gap 69 in this way, molten resin 71 is easily distributed uniformly in the circumferential direction through gap 69. As a result, the inner sleeve 31 and the permanent magnet 37 are aligned.

As described above, according to the structure of the motor rotor 25 of the present embodiment, the inner sleeve 31 and the permanent magnet 37 can be aligned by a simple method in which the small diameter portion 61 is provided in the inner sleeve 31.

In addition, the groove 65 formed in the outer peripheral surface 31a of the inner sleeve 31 extends in a direction including the circumferential component. Thereby, the groove 65 guides the flow of the molten resin 71 in the direction including the circumferential component. Therefore, the groove 65 promotes the flow of the molten resin 71 in the circumferential direction in the gap 69. Therefore, even if the groove 65 is present, the molten resin 71 is easily spread uniformly over the gap 69 in the circumferential direction. As shown in fig. 5, a space 75 is formed between the left end surface 37a of the permanent magnet 37 and the mold 70 during injection molding. The space 75 functions as a resin storage portion, and spreads the molten resin 71 in the circumferential direction. Therefore, the flow of the molten resin 71 in the circumferential direction in the gap 69 is further promoted.

Further, the resin portion 50 is formed by entering the groove 65, so that the adhesion between the resin portion 50 and the inner sleeve 31 is improved, and further, the adhesion between the inner sleeve 31 and the permanent magnet 37 is improved. The grooves 65 extend in a direction including the circumferential component, and therefore improve the fit in the axial direction in particular. As a result, the permanent magnet 37 is prevented from being displaced in the axial direction with respect to the inner sleeve 31. Further, since the groove 65 includes the damask knurled groove 66b, the permanent magnet 37 can be prevented from being positionally displaced with respect to the inner sleeve 31 in the circumferential direction.

The present disclosure is representative of the above-described embodiments, and can be implemented in various forms by making various changes and improvements based on the knowledge of those skilled in the art. Further, a modification may be configured by using the technical matters described in the above-described embodiments. The structures of the respective embodiments may be appropriately combined and used.

In the embodiment, the coupling of the inner socket 31 and the permanent magnet 37 having the hollow structure has been described, but the above-described structure may be applied to a case where the permanent magnet 37 and the shaft portion having the solid structure are coupled, for example.

Description of the reference numerals

A motor rotor; an inner sleeve (shaft portion); an outer peripheral surface; a permanent magnet; inner peripheral surface; inner peripheral surface; a resin portion; 61.. small diameter section; a conical portion; a stepped small diameter portion; 63.. central portion; 65.. a slot; a circumferential groove; a damask mesh knurl groove.