Hollow shaft motor rotor

Abstract

To provide a rotor for a hollow shaft motor, which simplifies the manufacturing process, eliminates assembly tolerances, easily and firmly achieves coupling of a magnet provided to a rotor core, improves productivity, and reduces manufacturing costs. [Solution] The rotor of the hollow shaft motor according to the present invention is characterized by including a rotor core (110) having a plurality of magnets, and a hollow shaft housing (120) formed around the rotor core (110) by placing the rotor core (110) in a die-casting mold using molten metal.

Description

[Technical Field]

[0001] The present invention relates to a hollow shaft motor, and more particularly to a rotor for a hollow shaft motor having a structure suitable for manufacturing by die casting. [Background technology]

[0002] Generally, the force acting on the brakes in a braking system is derived from the pressure generated in a master cylinder. A widely used technology uses an electric motor to generate pressure in the master cylinder of such a braking system. Such electric motors are usually called hollow shaft motors because they include a ball screw that rotates a hollow shaft, a ball nut that moves up and down as the ball screw rotates, and a ball screw that is connected to the hollow shaft and rotates together inside the hollow shaft.

[0003] As disclosed in Korean Patent Registration No. 10-2190270, a rotor for a conventional hollow shaft motor includes a hollow cylindrical housing with an interior, and a rotor core with multiple magnets attached to the outer periphery of the hollow shaft. Here, the hollow shaft is often made of a pressed metal material, and the rotor core is often press-fitted into the pressed hollow shaft.

[0004] When the rotor core is press-fitted into the hollow shaft or bonded with other methods such as glue, precise numerical accuracy is required during the bonding process. If a precise range of assembly tolerance occurs, it is difficult to maintain the concentricity of the rotating hollow shaft, which may result in the brake system not operating normally.

[0005] Also, Korean Patent No. 10-2634721 discloses a technique for fastening a rotor can around a magnet attached to the outer periphery of a rotor core to prevent the magnet from coming off.

[0006] According to this prior art, since a separate part must be attached to the outer circumferential surface of the rotor core, there are problems of the occurrence of the above-mentioned assembly tolerances and difficulty in maintaining concentricity, and there are problems of an increase in the number of manufacturing processes and a decrease in productivity.

[0007] Therefore, the present invention proposes a rotor for a hollow shaft motor that can solve the above-mentioned problems by making it possible to manufacture the hollow shaft by die casting instead of by pressing. Summary of the Invention [Problem to be solved by the invention]

[0008] SUMMARY OF THE INVENTION An object of the present invention is to provide a rotor for a hollow shaft motor which simplifies the manufacturing process and eliminates assembly tolerances.

[0009] Another object of the present invention is to provide a rotor for a hollow shaft motor that can easily and firmly bond a magnet provided in a rotor core.

[0010] Another object of the present invention is to provide a rotor for a hollow shaft motor, which can improve productivity by simplifying the assembly process and reduce manufacturing costs.

[0011] The above objects and other inherent objects of the present invention are all readily attained by the invention as described below. [Means for solving the problem]

[0012] The rotor of the hollow shaft motor according to the present invention comprises: a rotor core 110 having a plurality of magnets 130; The rotor core 110 is placed in a die-casting mold, and a hollow shaft housing 120 is formed around the rotor core 110 by molten metal.

[0013] In the present invention, the hollow shaft housing 120 includes an upper core cover part 121 formed on the upper surface of the rotor core 110; an upper support part 122 formed in a cylindrical shape on the upper part of the upper core cover part 121; The upper support 122 may include an upper bearing support 123 formed on the upper part of the upper support 122 .

[0014] In the present invention, the upper core cover part 121 may have a plurality of upper fixing points 121A formed at regular intervals so that both ends of the magnet inserted into the rotor core 110 are exposed.

[0015] In the present invention, the hollow shaft housing 120 includes a lower core cover part 124 formed on the lower surface of the rotor core 110; a lower support portion 125 formed at a lower portion of the lower core cover portion 124 and having a shape whose diameter decreases toward the lower portion; a lower bearing support portion 126 formed at a lower portion of the lower support portion 125 and having a cylindrical shape; The lower bearing support portion 126 may include a ball screw coupling portion 126A formed at a lower end thereof.

[0016] In the present invention, a plurality of lower fixing points 124A may be formed on the lower core cover part 124 at regular intervals so that both ends of the magnet of the rotor core are exposed.

[0017] In the present invention, the lower core cover part 124 may have a plurality of core fixing holes 124B formed at regular intervals.

[0018] In the present invention, a magnet support portion 128 and magnet end support portions 128A are formed around the magnet 130 of the rotor core 110, The rotor core 110 may have a core inner support portion 129 formed on an inner circumferential surface thereof.

[0019] In the present invention, an inner surface groove 111F may be formed on the inner circumferential surface of the rotor core 110.

[0020] The rotor of the hollow shaft motor according to the present invention comprises: a rotor core 110 having a plurality of magnets 130 inserted into magnet insertion portions 111A; The rotor core 110 is placed in a die-casting mold, and a hollow shaft housing 120 is formed around the rotor core 110 and around the magnet 13 inserted into the magnet insertion portion 111A using molten metal. [Effects of the Invention]

[0021] The present invention provides a rotor for a hollow shaft motor that has a more precise structure and good concentricity by eliminating the assembly tolerance that occurs when assembling a hollow shaft housing and a rotor core.

[0022] Furthermore, the present invention can eliminate assembly tolerances of the magnets while firmly and easily achieving connection of the magnets to the rotor core.

[0023] Furthermore, the present invention has the effect of simplifying the assembly process, improving productivity, reducing manufacturing costs, and providing a rotor for a hollow shaft motor with excellent quality. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a perspective view of a hollow shaft motor to which a rotor according to the present invention is applied, as viewed from above; [Figure 2] 1 is a perspective view of a hollow shaft motor to which a rotor according to the present invention is applied, as seen from below; [Figure 3] 1 is a perspective view from above showing a rotor according to the present invention; FIG. [Figure 4] FIG. 2 is a perspective view from below showing the rotor according to the present invention. [Figure 5] 1 is a perspective view of a rotor core and a die-cast portion applied to a rotor according to the present invention, viewed from above, with the rotor core and the die-cast portion separated from each other; [Figure 6] 1 is a perspective view of a rotor according to the present invention, showing a rotor core and a die-cast portion separated from each other, as viewed from below. [Figure 7] 1 is a plan view showing a rotor core of a rotor according to the present invention; [Figure 8] 1 is an exploded perspective view of a rotor core of a rotor according to the present invention; [Figure 9] 1 is an exploded perspective view of a rotor core and a magnet in a rotor according to the present invention; [Figure 10] 1 is a plan view showing a core body of a rotor core in a rotor according to the present invention; [Figure 11] 1 is a plan view showing a lower cover member or an upper cover member of a rotor according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] FIG. 1 is a perspective view of a hollow shaft motor 1 to which a rotor 10 according to the present invention is applied, as seen from above, and FIG. 2 is a perspective view of the hollow shaft motor 1 as seen from below.

[0026] 1 and 2, a rotor 10 according to the present invention, together with a motor housing 20, constitutes a hollow shaft motor 1. That is, the hollow shaft motor 1 is made up of the rotor 10 and the motor housing 20. The rotor 10 is located inside the motor housing 20 and is rotatably coupled to the inside of the motor housing 20.

[0027] The motor housing 20 includes a housing body 21, a flange 22 formed on the upper part of the housing body 21 and extending outward, a bus bar body 23 coupled to the upper part of the housing body 21, and a terminal cover 24 coupled to one side of the bus bar body 23 for connecting an external power source.

[0028] A stator (not shown) is provided in the housing body 21. When the rotor 10 is positioned inside the housing body 21 and power is applied to the stator, a changing magnetic field generated by the stator affects the magnets 130 provided on the rotor 10, causing the rotor 10 to rotate. The rotation of the upper and lower parts of the rotor 10 is supported by bearings (not shown) provided in the bus bar body 23 and / or the housing body 21. A lower protrusion 211 that protrudes downward is formed at the lower end of the housing body 21, and the lower part of the rotor 10 is exposed inside the lower protrusion 211. A cover (not shown) that covers the exposed part may be coupled to the lower protrusion 211.

[0029] FIG. 3 is a perspective view from above showing the rotor 10 according to the present invention, FIG. 4 is a perspective view from below of the rotor 10, FIG. 5 is a perspective view from above of the rotor core 110 and hollow shaft housing 120 applied to the rotor according to the present invention, separated from each other, and FIG. 6 is a perspective view from below of the rotor core 110 and hollow shaft housing 120, separated from each other.

[0030] 3 to 6, the rotor 10 of the hollow shaft motor according to the present invention comprises a rotor core 110 and a hollow shaft housing 120 formed around the rotor core 110. The inner space of the rotor core 110 and the hollow shaft housing 120 is a hollow portion C in which a ball screw (not shown) and a ball nut (not shown) are positioned.

[0031] The rotor core 110 includes a core body 111 manufactured by stacking a number of laminar members 111' formed by pressing thin electrical steel sheets, and a plurality of magnets 130 provided in the core body 111. The detailed structure of the rotor core 110 will be described again below.

[0032] The hollow shaft housing 120 is manufactured by placing the rotor core 110 in a die-casting mold and then injecting molten metal into the mold to form the hollow shaft housing 120. The molten metal used as the die-casting material may be an alloy of copper, zinc, aluminum, tin, magnesium, or the like.

[0033] Thus, the hollow shaft housing 120 formed on the rotor core 110 by die casting includes a ring-shaped upper core cover part 121 formed on the upper surface of the rotor core 110, a cylindrical upper support part 122 formed by extending upward from the upper core cover part 121, and a cylindrical upper bearing support part 123 formed by extending upward from the upper support part 122.

[0034] The hollow shaft housing 120 also includes a ring-shaped lower core cover part 124 formed on the lower surface of the rotor core 110, a lower support part 125 extending downward from the lower core cover part 124 and having a shape in which the diameter decreases toward the bottom, and a cylindrical lower bearing support part 126 extending from the bottom of the lower support part 125. A ball screw coupling part 126A to which a ball screw (not shown) is coupled is formed at the lower end of the lower bearing support part 126.

[0035] The core outer support portion 127 is formed along the outer surface grooves 111D, 112D, and 113D formed on the outer peripheral surface of the rotor core 110, and the core outer support portion 127 connects the upper core cover portion 121 and the lower core cover portion 124 in the vertical direction.

[0036] The magnet support part 128 supports the outer diameter surface of the magnet 130 inserted into the rotor core 110, providing a bonding force between the magnet 130 and the rotor core 110. Magnet end support parts 128A are formed on both ends of the magnet support part 128, supporting both ends of the magnet 130 and providing a bonding force with the rotor core 110. The core inner support part 129 is formed on the inner circumferential surface of the rotor core. The magnet support part 128, the magnet end support parts 128A, and the core inner support part 129, together with the core outer support part 127, vertically connect the upper core cover part 121 and the lower core cover part 124.

[0037] A plurality of upper fixing points 121A are formed on the upper core cover part 121. A plurality of lower fixing points 124A and core fixing holes 124B are formed on the lower core cover part 124.

[0038] The upper fixing point 121A is formed in a hole shape so that a portion of the bridge 113-3 of the upper cover member 113 that constitutes the rotor core 110 is exposed. It is possible to visually check through the upper fixing point 121A whether the molten material is sufficiently filled around the bridge 113-3 and whether the magnet support portion 128 and the magnet both end support portions 128A are properly formed. Similarly, the lower fixing point 124A is formed in a hole shape so that a portion of the bridge 112-3 of the lower cover member 112 that constitutes the rotor core 110 is exposed. It is possible to visually check through the lower fixing point 124A whether the molten material is sufficiently filled around the bridge 112-3 and whether the magnet support portion 128 and the magnet both end support portions 128A are properly formed.

[0039] The core fixing hole 124B is formed to communicate with the rotor core fixing holes 111C and 112C of the rotor core 110. The core fixing hole 124B is formed in the lower core cover part 124 to communicate with the rotor core fixing holes 111C and 112C so that pins of a die-casting mold can be inserted into the rotor core fixing holes 111C and 112C to fix the rotor core 110 within the mold. All of the components of the hollow shaft housing 120 are integrally formed as a single member using die-casting material.

[0040] Figure 7 is a plan view showing the rotor core 110 of the rotor 10 according to the present invention, Figure 8 is an exploded perspective view of the rotor core 110 of the rotor 10 according to the present invention, and Figure 9 is an exploded perspective view of the rotor core 110 and magnet 130 from the rotor 10 according to the present invention.

[0041] As shown in FIGS. 7 to 9, a rotor core 110 of the present invention includes a core body 111, a lower cover member 112, an upper cover member 113, and a magnet .

[0042] The core body 111 is manufactured by stacking a large number of laminar members 111' formed by pressing. The core body 111 comprises an inner body 111-1 and an outer frame 111-2, and the inner body 111-1 and the outer frame 111-2 are connected by a plurality of bridges 111-3 formed at regular intervals.

[0043] The space formed by the inner main body 111-1, the outer frame 111-2, and the bridge 111-3 serves as a magnet insertion portion 111A that is formed by being penetrated vertically.

[0044] Each magnet 130 is inserted into a magnet insertion portion 111A and coupled to the outer surface of the inner body 111-1. A pair of magnet fixing protrusions 111B may be formed on the inner body 111-1 for each magnet insertion portion 111A to support both circumferential sides of the magnet 130 within the magnet insertion portion 111A. Therefore, when the magnet 130 is inserted into the magnet insertion portion 111A, the inner surface of the magnet 130 abuts against the outer surface of the inner body 111-1, and both circumferential ends of the magnet 130 are supported by the magnet fixing protrusions 111B.

[0045] A gap 111A' is formed at a fixed interval between the outer surface of the magnet 130 provided in the magnet insertion portion 111A and the inner surface of the outer frame 111-2. In addition, two-side passages 111A" are formed between both circumferential sides of the magnet 130 and the bridge 111-3. When forming the hollow shaft housing 120, molten metal, which is a die-casting material, is filled into the gap 111A' to form the magnet support portion 128. In addition, the molten metal is filled into the two-side passages 111A" to form the magnet both-end support portions 128A.

[0046] The inner body 111-1 of the core body 111 has a plurality of rotor fixing holes 111C formed in the vertical direction. The rotor fixing holes 111C are formed so that pins of a mold can be inserted to fix the rotor core 110 during the die-casting process. In FIG. 7, four rotor fixing holes 111C are formed symmetrically at 90° intervals about the central axis of the rotor core 110, but the number and positions of the rotor fixing holes 111C are not particularly limited, and it is preferable to form at least three rotor fixing holes 111C in symmetrical positions. Furthermore, the rotor fixing holes 111C may be formed so as to penetrate in the vertical direction, or, as necessary, holes may be formed only on the lower side, or holes may be formed at a fixed depth on both the lower and upper sides.

[0047] The outer surface groove 111D is a groove formed in the vertical direction on the outside of the outer frame 111-2 of the core body 111. When a molten metal, which is a die-casting material, is filled into the outer surface groove 111D, the core outer support portion 127 is formed.

[0048] The embossments 111E are formed to bond the lamina members 111' to each other while they are stacked. The embossments 111E can be omitted if necessary, and the bonding between the lamina members can be performed by bonding or adhesive coating. In particular, a self-bonding (SB) electrical steel sheet can be used, which is the base material for manufacturing the lamina members 111', and has an adhesive coating layer pre-formed on its surface. In this case, the high-temperature environment provided in the die-casting mold can have the effect of partially hardening the adhesive coating layer during the die-casting process.

[0049] The inner side groove 111F is a groove that increases the bonding strength when molten metal, as a die-casting material, forms the core inner support portion 129 on the inner circumferential surface of the rotor core 110 and prevents the die-cast portion from coming off during rotation of the rotor 10. The inner side groove 111F forms the core inner support portion 129 on the inner circumferential surface of the rotor core 110 at the same time that the molten metal is filled into the inner side groove 111F. That is, the core inner support portion 129 may be formed to surround the inner side groove 111F and the entire inner circumferential surface of the rotor core 110. Therefore, the inner space of the core inner support portion 129 forms the hollow portion C. This inner side groove 111F can increase the bonding strength between the rotor core 110 and the hollow shaft housing 120 of the rotating rotor 10.

[0050] FIG. 10 is a plan view showing a core body 111 of a rotor core in a rotor according to the present invention, and FIG. 11 is a plan view showing a lower cover member 112 or an upper cover member 113 in a rotor according to the present invention.

[0051] 10 and 11, the rotor core 110 of the present invention includes a lower cover member 112, a core body 111 in which a number of laminar members 111' are laminated, and an upper cover member 113.

[0052] The lower cover member 112, the plurality of laminar members 111', and the upper cover member 113 can be manufactured by processing electrical steel sheets using a progressive die in one press machine.

[0053] A number of lamina members 111' are stacked to form the core body 111. The lamina member 111' has an inner body 111-1 and an outer frame 111-2, with a plurality of bridges 111-3 formed at regular intervals to connect the inner body 111-1 and the outer frame 111-2. The magnet insertion portion 111A is formed in the space between the inner body 111-1, the outer frame 111-2, and the bridges 111-3. A plurality of magnet fixing protrusions 111B are provided on the outer surface of the inner body 111-1 to fix the magnet 130.

[0054] A plurality of rotor core fixing holes 111C are formed at regular intervals in the inner body 111-1. The rotor core fixing holes 111C may be formed in all of the lamina members 111' constituting the core body 111, or may be formed in only some of the lamina members 111'. A plurality of outer surface grooves 111D are formed in the outer frame.

[0055] The embossments 111E are formed by pre-molding to bond between laminar members, and have a downwardly protruding shape while providing a bonding groove upward. Therefore, the embossments 111E of one laminar member 111' are bonded to the embossments 111E of the laminar member 111' below it. If the bonding between laminar members is performed by bonding or other methods, the embossments 111E can be omitted.

[0056] A large number of lamina members 111' are stacked on the inside of the inner main body 111-1 of the lamina member 111', and inner side surface grooves 111F are formed in the vertical direction on the inner surface of the rotor core 110.

[0057] The lower cover member 112 and the upper cover member 113 can be manufactured using the same press die as the lamina member 111'. The lower cover member 112 and the upper cover member 113 can be manufactured by pressing the outer frame 112-2 of the lamina member 111' formed using the press die with a mechanism such as a side press to form the outer frames 111-2 and 113-2 so as to cover part of the magnet insertion portion 111A of the lamina member 111'. Therefore, the outer frames 111-2 and 113-2 can prevent the magnet inserted in the magnet insertion portion 111A of the rotor core 110 from falling off to the upper or lower part during die-cast molding.

[0058] The lower cover member 112 formed using a press die is positioned at the bottom, and the core body 111, on which a number of laminar members 111' are stacked, is positioned above it, and the upper cover member 113 is stacked and coupled to the top of the core body 111. With the magnet 130 inserted into the magnet insertion portion 111A, the outer frames 112-2 and 113-2 of the lower cover member 112 and the upper cover member 113 are pressed by a mechanism such as a side press, and the outer frames 112-2 and 113-2 are deformed by bending toward the inner frames 112-1 and 113-1, thereby completing the shapes of the lower cover member 112 and the upper cover member 113.

[0059] The lower cover member 112 has embossed coupling holes 112E formed at positions corresponding to the embossments 111E of the lamina member 111'. Therefore, the lamina member 111' can be stacked and coupled to the upper part of the lower cover member 112. The upper cover member 113 has embossments 113E formed at positions corresponding to the embossments 111E of the lamina member 111'. Therefore, the embossments 113E of the upper cover member 113 can be coupled to the embossments 111E of the lamina member 111' located at the top of the core body 111. In a structure in which the lower cover member 112 and the upper cover member 113 are not used, the embossments 111E of the lamina member 111' located at the bottom are formed into embossed coupling holes by piercing.

[0060] It should be understood that the above description of the present invention is merely an example for understanding the present invention and is not intended to define the scope of the present invention. The scope of the present invention is defined by the appended claims, and it should be understood that any mere modification or change of the present invention within this scope falls within the scope of protection of the present invention. [Explanation of symbols]

[0061] 1: Hollow shaft motor 10: Rotor 20: Motor housing 21: Housing body 22: Flange 23: Busbar body 24: Terminal cover 110: Rotor core 111: Core body 111-1: Inner body 111-3, 112-3, 113-3: Bridge 111A: Magnet insertion part 111A': Gap 111A”: Double aisle 111': Lamina member 111B, 112B, 113B: Magnet fixing protrusion 111C, 112C, 113C: Rotor fixing hole 111D, 112D, 113D: Outer groove 111E, 113E: Embossed 111F:Inner groove 112: Lower cover member 112-1, 113-1: Inner frame 112-2, 113-2: Outer frame 112-3, 113-3: Bridge 112E: Embossed connecting hole 113: Upper cover member 120: Hollow shaft housing 121: Upper core cover part 121A: Upper fixed point 122: Upper support part 123: Upper bearing support 124: Lower core cover part 124A: Lower fixed point 124B: Core fixing hole 125: Lower support part 126: Lower bearing support 126A: Ball screw joint 127: Core outer support 128: Magnet support part 128A: Magnet support part 129: Core inner support 130: Magnet 211: Lower protrusion C: Hollow part

Claims

1. A rotor for a hollow shaft motor, a rotor core (110) having a plurality of magnets (130); The rotor core (110) is placed in a die-casting mold, and a hollow shaft housing (120) is formed around the rotor core (110) by a metal melt. The rotor of the hollow shaft motor comprises:

2. The hollow shaft housing (120) an upper core cover part (121) formed on the upper surface of the rotor core (110); an upper support part (122) formed in a cylindrical shape on the upper part of the upper core cover part (121); The rotor of a hollow shaft motor according to claim 1, further comprising an upper bearing support portion (123) formed on an upper portion of the upper support portion (122).

3. The upper core cover part (121) is provided with a plurality of upper fixing points (121A) at regular intervals so that both ends of the magnet inserted into the rotor core (110) are exposed.

3. The rotor of a hollow shaft motor according to claim 2.

4. The hollow shaft housing (120) a lower core cover portion (124) formed on the lower surface of the rotor core (110); a lower support portion (125) formed at a lower portion of the lower core cover portion (124) and having a shape whose diameter decreases toward the lower portion; a lower bearing support portion (126) formed at a lower portion of the lower support portion (125) and having a cylindrical shape; and a ball screw coupling portion (126A) formed at the lower end of the lower bearing support portion (126).

2. The rotor of a hollow shaft motor according to claim 1.

5. The lower core cover part (124) is formed with a plurality of lower fixing points (124A) at regular intervals so that both ends of the magnet of the rotor core are exposed.

5. The rotor of a hollow shaft motor according to claim 4.

6. The lower core cover portion (124) is characterized in that a plurality of core fixing holes (124B) are formed at regular intervals.

5. The rotor of a hollow shaft motor according to claim 4.

7. A magnet support portion (128) and magnet end support portions (128A) are formed around the magnet (130) of the rotor core (110), The rotor core (110) is characterized in that a core inner support portion (129) is formed on the inner peripheral surface thereof.

2. The rotor of a hollow shaft motor according to claim 1.

8. The rotor core (110) has an inner surface groove (111F) formed on its inner circumferential surface.

8. The rotor of a hollow shaft motor according to claim 7.

9. A rotor for a hollow shaft motor, a rotor core (110) in which a plurality of magnets (130) are inserted into magnet insertion portions (111A); and The rotor core (110) is placed in a die-casting mold, and a hollow shaft housing (120) is formed around the rotor core (110) and the magnet (13) inserted into the magnet insert portion (111A) by a metal melt. The rotor of the hollow shaft motor comprises:

10. The hollow shaft housing (120) an upper core cover part (121) formed on the upper surface of the rotor core (110); an upper support part (122) formed in a cylindrical shape on the upper part of the upper core cover part (121); and an upper bearing support portion (123) formed on the upper portion of the upper support portion (122). The rotor of a hollow shaft motor according to claim 9.

11. The upper core cover part (121) is provided with a plurality of upper fixing points (121A) at regular intervals so that both ends of the magnet inserted into the rotor core (110) are exposed. The rotor of a hollow shaft motor according to claim 10.

12. The hollow shaft housing (120) a lower core cover portion (124) formed on the lower surface of the rotor core (110); a lower support portion (125) formed at a lower portion of the lower core cover portion (124) and having a shape whose diameter decreases toward the lower portion; a lower bearing support portion (126) formed at a lower portion of the lower support portion (125) and having a cylindrical shape; and a ball screw coupling portion (126A) formed at the lower end of the lower bearing support portion (126). The rotor of a hollow shaft motor according to claim 9.

13. The lower core cover part (124) is formed with a plurality of lower fixing points (124A) at regular intervals so that both ends of the magnet of the rotor core are exposed. The rotor of a hollow shaft motor according to claim 12.

14. The lower core cover portion (124) is characterized in that a plurality of core fixing holes (124B) are formed at regular intervals. The rotor of a hollow shaft motor according to claim 12.

15. A magnet support portion (128) and magnet end support portions (128A) are formed around the magnet (130) of the rotor core (110), The rotor core (110) is characterized in that a core inner support portion (129) is formed on the inner peripheral surface thereof. The rotor of a hollow shaft motor according to claim 13.

16. The rotor core (110) has an inner surface groove (111F) formed on its inner circumferential surface.

16. The rotor of a hollow shaft motor according to claim 15.

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