Magnet holder and rotor for electric motor

Abstract

To provide a magnet holder that has good assemblability, easily and surely fixes a magnet, and prevents the magnet from scattering as magnet holding means for an IPM motor.SOLUTION: A magnet holder 8 is used for an IPM motor having a rotor core in which a plurality of magnet mounting holes are formed. The magnet holder 8 is formed of synthetic resin and has a disk-shaped base part 11 mounted on an axial end surface of the rotor core. On one surface side of the base part 11, a core contact part 15 in contact with a rotor core end surface and a projection part 14 inserted into the magnet mounting hole are provided. The core contact part 15 covers the axial end of the magnet mounting hole to regulate axial movement of the magnet. The projection part 14 abuts on a radial end surface of the magnet in the magnet mounting hole to regulate radial movement of the magnet.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a magnet holder for holding a magnet used in an electric motor, and more particularly to a magnet holder used in the rotor of an interior permanent magnet (IPM) motor, and a rotor using the magnet holder. [Background technology]

[0002] In recent years, the use of brushless motors with an IPM structure (hereafter referred to as IPM motors), in which magnets are embedded in the rotor, has been increasing as drive sources for electric vehicles, hybrid vehicles, etc. IPM motors can utilize both the torque from the magnet and the reluctance torque that accompanies the magnetization of the rotor, and because the magnet does not detach from the rotor while the motor is rotating, they are widely used in fields that require high performance and mechanical reliability.

[0003] On the other hand, IPM motors require some kind of magnet retention means to prevent the magnets embedded in the rotor from popping out. For example, in the motor described in JP 2010-63285 A, the entire rotor is molded with synthetic resin while the magnets are embedded in it, preventing the magnets from popping out of the rotor. Other magnet retention methods that have been known include adhesively fixing the magnets in the rotor or using leaf springs to fix the magnets in the rotor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-63285 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the case of a method such as that described in Patent Document 1, in which the entire rotor is resin-molded to prevent the magnets from scattering, the molding process increases the number of steps required, which increases the rotor production costs. As a result, the resin-molding method poses problems in terms of cost and productivity. Furthermore, similar problems arise in terms of the number of steps and parts required when using adhesives or springs for fixing, and improvements have been sought.

[0006] An object of the present invention is to provide a magnet holder as a magnet holding means for an IPM motor, which is easy to assemble, can fix a magnet easily and reliably, and can prevent the magnet from scattering. [Means for solving the problem]

[0007] The magnet holder of the present invention is a magnet holder that is attached to a rotor for an electric motor having a rotor shaft, a rotor core attached to the rotor shaft and having a plurality of magnet mounting holes formed circumferentially, and magnets arranged in the magnet mounting holes, and is characterized in that the magnet holder has a base portion that is attached to the axial end surface of the rotor core and is formed in a circular plate shape, a core contact portion that is provided on one side of the base portion and contacts the end surface of the rotor core, and a protrusion that protrudes from the one side, extends axially, and is inserted into the magnet mounting hole.

[0008] The magnet holder of the present invention is attached to the end of the rotor core by inserting its protrusion into the magnet mounting hole of the rotor core. This covers the end of the magnet mounting hole of the rotor core with the core contact part of the magnet holder, preventing the magnet from falling out and scattering. Furthermore, the protrusion inserted into the magnet mounting hole positions the magnet radially and prevents the magnet from tipping over.

[0009] In the magnet holder, the core contact portion may cover the axial end of the magnet mounting hole and restrict axial movement of the magnet, and the protrusion portion may abut against the radial end face of the magnet within the magnet mounting hole and restrict radial movement of the magnet.

[0010] The core contact portions may also include a first core contact portion provided on the outer periphery of the base portion and a second core contact portion provided radially inward of the first core contact portion, with the upper surface of the second core contact portion set at the same height as the upper surface of the first core contact portion. This allows the magnet holder to come into surface contact with the rotor core end face at both the outer periphery and its radially inner position, stabilizing the contact surface between the rotor core and the magnet holder. In this case, the first core contact portion and the second core contact portion may be provided integrally, or the first core contact portion and the second core contact portion may be provided separately.

[0011] Furthermore, a recess may be provided on one side of the base portion, the bottom surface of which is positioned lower than the upper surface of the core contact portion, and the protrusion may protrude from the bottom surface of the recess, and a curved surface portion may be formed at the base of the protrusion, rising from the bottom surface of the recess, so that the height from the bottom surface of the recess to the upper surface of the core contact portion is higher than the height from the bottom surface of the recess to the upper end of the curved surface portion, and the upper end of the curved surface portion may be positioned lower than the upper surface of the core contact portion. In this way, when the magnet holder is attached to the rotor core end face, the curved surface portion formed at the base of the protrusion fits into the recess, and does not abut the rotor core end face. This prevents the magnet holder from floating up from the rotor core end face when the core is attached.

[0012] In addition, a through hole may be provided radially outward of the protrusion of the base portion, penetrating the base portion in the axial direction, and this through hole may be open to face the magnet in the magnet mounting hole when the magnet holder is attached to the end face of the rotor core. This allows the rotor with the magnet holder attached to be magnetized and manufactured using a rotor manufacturing device, thereby improving productivity through automatic assembly.

[0013] On the other hand, a rotor for an electric motor according to the present invention is a rotor for an electric motor including a rotor shaft, a rotor core attached to the rotor shaft and having a plurality of magnet mounting holes formed along a circumferential direction, and magnets arranged in the magnet mounting holes, the rotor has a magnet holder attached to an axial end surface of the rotor core, The magnet holder is characterized by having a base portion formed in a circular plate shape, a core contact portion provided on one side of the base portion and contacting the end face of the rotor core, and a protrusion portion protruding from the one side, extending axially, and inserted into the magnet mounting hole.

[0014] In the rotor for an electric motor of the present invention, a magnet holder is attached to the end of the rotor core. The magnet holder is attached to the end of the rotor core by inserting its protrusion into the magnet mounting hole of the rotor core. This covers the end of the magnet mounting hole of the rotor core with the core contact part of the magnet holder, preventing the magnet from falling out and scattering. Furthermore, the protrusion inserted into the magnet mounting hole positions the magnet radially and prevents the magnet from tipping over. [Effects of the Invention]

[0015] According to the magnet holder of the present invention, the magnet holder is attached to a rotor for an electric motor having a rotor core with a plurality of magnet mounting holes for accommodating magnets, and is provided with a disk-shaped base portion attached to the axial end face of the rotor core, a core contact portion provided on one side of the base portion that contacts the end face of the rotor core, and a protrusion protruding from one side that is inserted into the magnet mounting hole.By attaching the magnet holder to the end of the rotor core, the end of the magnet mounting hole of the rotor core is covered by the core contact portion of the magnet holder, making it possible to prevent the magnet from falling out or scattering.In addition, the protrusion inserted into the magnet mounting hole can position the magnet radially and prevent the magnet from tipping over.

[0016] Furthermore, according to the rotor for an electric motor of the present invention, the rotor for an electric motor has a rotor core with a plurality of magnet mounting holes to accommodate magnets, and is provided with a magnet holder having a disk-shaped base portion attached to the axial end face of the rotor core, a core contact portion provided on one side of the base portion that contacts the end face of the rotor core, and a protrusion provided on one side that is inserted into the magnet mounting hole.As a result, the ends of the magnet mounting holes in the rotor core are covered by the core contact portion of the magnet holder, preventing the magnets from falling out and scattering.In addition, the protrusions inserted into the magnet mounting holes can position the magnets radially and prevent the magnets from tipping over. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is an explanatory diagram showing the configuration of a rotor using a magnet holder according to the present invention. [Figure 2] FIG. 2 is an exploded perspective view of the rotor of FIG. 1. [Figure 3] 1 is an explanatory diagram showing the configuration of a magnet holder according to a first embodiment of the present invention. [Figure 4] 2 is an explanatory diagram showing the configuration of a rotor manufacturing apparatus capable of manufacturing the rotor of FIG. 1. FIG. [Figure 5]FIG. 2 is an explanatory diagram showing the configuration of a magnetizing yoke. [Figure 6] FIG. 2 is an explanatory diagram showing the configuration in the vicinity of a magnetizer. [Figure 7] 5 is an explanatory diagram showing a rotor manufacturing process using the rotor manufacturing apparatus of FIG. 4. [Figure 8] 10 is an explanatory diagram showing the configuration of a magnet holder according to a second embodiment of the present invention. FIG. [Figure 9] 9 is an explanatory view showing the flow of resin during molding in the magnet holder of FIG. 8. FIG. [Figure 10] 10A and 10B are explanatory diagrams showing modified examples of the magnet holder according to the present invention. [Figure 11] 10A and 10B are explanatory views showing another modified example of the magnet holder according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] (Embodiment 1) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Fig. 1 is an explanatory diagram showing the overall configuration of a rotor 1 using a magnet holder according to a first embodiment of the present invention, and Fig. 2 is an exploded perspective view of the rotor 1. The rotor 1 is used in an inner rotor type IPM motor, and as shown in Figs. 1 and 2, has a configuration in which a cylindrical rotor core 3 is press-fitted and fixed to the outer periphery of a rotor shaft 2. The rotor core 3 is made of a magnetic material and is configured by laminating multiple, approximately circular, thin core plates (steel sheets).

[0019] An axial hole 4 is provided in the center of the rotor core 3. The rotor shaft 2 is press-fitted and fixed into the axial hole 4. A plurality of magnet mounting holes 5 are formed around the axial hole 4 along the circumferential direction. The magnet mounting holes 5 are provided radially, extending in the radial direction, giving the rotor 1 a so-called spoke-type configuration. Magnets (permanent magnets) 6 are inserted and housed in the magnet mounting holes 5.

[0020] In the rotor core 3 of this embodiment, ten magnet mounting holes 5 are provided at equal intervals along the circumferential direction, and ten magnets 6 are embedded in the rotor core 3. The magnets 6 are arranged so that adjacent magnets 6 in the circumferential direction have opposite polarities. In other words, there are five magnets 6 of the same polarity, and magnets 6 of opposite polarities are arranged alternately in the circumferential direction. Grooves 7 extending in the circumferential direction are formed on the inner periphery of the magnet mounting holes 5.

[0021] Magnet holders 8 made of synthetic resin (for example, PBT: polybutylene terephthalate) are attached to both ends of the rotor core 3 in the axial direction (direction in which the rotor shaft extends). These magnet holders 8 fix the magnets 6 in the radial direction and prevent them from jumping out of the rotor. In this case, because the magnet holders 8 are made of synthetic resin, they can be easily manufactured by molding, and manufacturing costs can be reduced by using multiple molds. In order to make the configuration of the rotor 1 easier to see, in Figure 1, the axial end faces 3a of the rotor core 3 (hereinafter referred to as rotor core end faces 3a), which would normally be hidden by the magnet holders 8, are shown with solid lines rather than hidden lines (dashed lines).

[0022] As shown in Figure 2, push nuts 9 are attached to both outer sides of the magnet holder 8. The magnet holder 8 is tightly fixed to the rotor core end face 3a by both push nuts 9. In the rotor 1, by attaching the magnet holder 8 so as to cover the rotor core end face 3a, the magnets 6 in the rotor core 3 are supported at both axial ends and held in the magnet mounting holes 5. As a result, the magnets 6 are prevented from coming off in the axial direction and from flying away from the rotor core 3.

[0023] Fig. 3 is an explanatory diagram showing the configuration of magnet holder 8 according to the first embodiment of the present invention. As shown in Fig. 3, magnet holder 8 is formed in a disk shape and has a base portion 11 with an outer diameter slightly smaller than or approximately the same as that of rotor core 3. A shaft hole 12 through which rotor shaft 2 is inserted is formed in the center of base portion 11. When magnet holder 8 is attached to rotor core 3 (hereinafter, this state will be referred to as "core attached"), shaft hole 12 faces and communicates with axial hole 4 of rotor core 3.

[0024] The base portion 11 is provided with pin insertion holes 13 (10 in this example) that face the magnet mounting holes 5 when the core is attached. The pin insertion holes 13 are provided to penetrate the base portion 11 in the axial direction, and are open to face the center of the magnet 6 housed in the magnet mounting hole 5 when the core is attached. These pin insertion holes 13 are used in the rotor manufacturing process, which will be described later, and hold-down pins are inserted into them from the axial direction.

[0025] A protrusion 14 is provided on one surface of the base portion 11 (the side that contacts the rotor core end face 3a when the core is attached; the same applies below) to be inserted into the groove 7 of the rotor core 3. Furthermore, a core contact portion (first core contact portion) 15 is provided radially outward from the protrusion 14, and is formed in a flat shape along the outer periphery of the base portion 11. The core contact portion (first core contact portion) 15 contacts the rotor core end face 3a when the core is attached. A recess 16 is formed around the protrusion 14, extending radially from the periphery 12a of the shaft hole 12 (hereinafter referred to as the shaft hole periphery 12a) to surround the protrusion 14. The recess 16 is recessed by one step (approximately 1 mm) from the core contact portion 15, and a peripheral wall (second core contact portion) 17 is formed around the recess 16, which is integrally formed flush with the core contact portion 15 and at the same height.

[0026] The peripheral wall 17 extends continuously radially inward from the core contact portion 15 to the shaft hole periphery 12a. When the core is installed, the peripheral wall 17 and the upper surface of the core contact portion 15, which are flush with each other, come into direct contact with the rotor core end face 3a. In other words, the peripheral wall 17 also functions as a core contact portion that comes into contact with the rotor core end face 3a when the core is installed. As a result, the magnet holder 8 makes surface contact with the rotor core end face 3a along the radial direction from the outer periphery to the inner periphery (position of the shaft hole 12) of the base portion 11. This stabilizes the contact surface between the rotor core 3 and the magnet holder 8, improving the positioning accuracy of the magnet 6. Furthermore, the load when the push nut 9 is installed can be supported by the entire radial surface.

[0027] Ten protrusions 14 are provided radially inside the pin insertion holes 13, corresponding to the number of magnets 6, and when a core is attached, they are inserted into grooves 7 on the radial inside of the magnet mounting hole 5. When a core is attached to the magnet holder 8, the radially outer surface 14a of each protrusion 14 (hereinafter abbreviated as protrusion outer surface 14a) faces and comes into contact with the radially inner surface 6a of the magnet 6 housed in the magnet mounting hole 5 (hereinafter abbreviated as magnet inner surface 6a) with a slight clearance between them. Because the protrusions 14 are parts that affect the positioning accuracy of the magnet 6, their height is kept to a minimum necessary to facilitate dimensional accuracy (generally about twice the thickness of the base portion 11).

[0028] From the viewpoints of preventing stress concentration and molding, the base of the protrusion 14 is provided with a curved surface (so-called R) 14b that rises from the bottom surface 16a of the recess 16 (hereinafter abbreviated as recess bottom surface 16a). For this reason, if the protrusion 14 were to rise directly from the core contact portion 15, the end of the magnet 6 would ride up onto the curved surface 14b when the core is attached, causing the magnet holder 8 to float above the rotor core end surface 3a, which would also affect the magnet positioning accuracy. Therefore, the magnet holder 8 is provided with a recess 16 like a moat around the protrusion 14 to prevent the curved surface 14b from coming into contact with the end of the magnet 6 when the core is attached.

[0029] In this case, in magnet holder 8, protrusion 14 protrudes from recess bottom surface 16a, which is lower than core contact portion 15 and peripheral wall 17, and the height dimension from recess bottom surface 16a to the top surface of core contact portion 15 is greater than the height dimension of curved surface portion 14b (the dimension from recess bottom surface 16a to the top end of the curved surface portion). In other words, when the core is attached, the position of the top end of curved surface portion 14b is set lower than the top surfaces of core contact portion 15 and peripheral wall 17. Note that up and down and high and low here are based on the thickness direction of magnet holder 8 (the axial direction when the core is attached: the direction of arrow X in FIG. 3).

[0030] As a result, when the core is attached, the curved surface portion 14b fits into the recess 16, and a gap that exceeds the height dimension of the curved surface portion 14b is formed between the base side of the protrusion 14 and the rotor core end face 3a. In other words, the magnet holder 8 is designed so that the curved surface portion 14b and the end of the magnet 6 do not come into contact when the core is attached. Therefore, when the core is attached, the core contact portion 15 comes into contact with the rotor core end face 3a without floating up, and the magnet holder 8 is attached to the rotor core 3 in a tight fit.

[0031] Such magnet holders 8 are attached to both ends of the rotor core 3 by inserting the protrusions 14 into the grooves 7 of the rotor core 3. As a result, both ends of the magnet mounting hole 5 of the rotor core 3 are covered by the core contact portions 15 of the magnet holder 8, restricting axial movement of the magnets 6. In other words, the magnets 6 are prevented from falling out and scattering. Furthermore, when the core is attached, the protrusion outer surfaces 14a and the magnet inner surfaces 6a face and contact each other, restricting radial movement of the magnets 6. At this time, the movement of the radially outer surface of the magnet 6 is restricted by the outer peripheral wall of the magnet mounting hole 5. As a result, the magnets 6 are positioned radially within the magnet mounting hole 5, and it is possible to prevent the magnets 6 from tipping over toward the grooves 7.

[0032] Furthermore, recesses 16 are provided around the protrusions 14, so the magnet holder 8 does not lift off the rotor core end face 3a when the core is attached. In addition to the core contact portions 15, the base portion 11 is provided with a peripheral wall 17 extending radially inward, so the magnet holder 8 comes into surface contact with the rotor core end face 3a along the radial direction from the outer periphery to the shaft hole periphery 12a. As a result, the contact surface between the rotor core 3 and the magnet holder 8 is stabilized, ensuring the positioning accuracy of the magnet 6 by the protrusions 14 and improving positioning accuracy.

[0033] On the other hand, because magnet holder 8 is provided with pin insertion holes 13, rotor 1 equipped with it can be magnetized and manufactured using, for example, rotor manufacturing equipment 100 as shown in Fig. 4, making it possible to improve productivity through automated assembly. Fig. 4 is an explanatory diagram showing the configuration of a rotor manufacturing equipment used to manufacture rotor 1. Note that if an equipment such as rotor manufacturing equipment 100 is not used, there is no need to provide pin insertion holes 13, and a configuration without pin insertion holes 13 can also be used as the magnet holder.

[0034] As shown in Figure 4, a magnetizer 111 with multiple magnetizing parts arranged radially is disposed in the center of the rotor manufacturing apparatus 100, and magnetization and attachment of the magnets 6 are performed with the rotor 1 placed on the upper surface of the magnetizer 111. The magnetizer 111 is installed on a magnetizer base 112 disposed in the center of the rotor manufacturing apparatus 100. A cylindrical case 113 is placed on the magnetizer base 112, and a magnetizing yoke 114 formed in a generally pentagonal prism shape is housed inside the case 113. Figure 5 is an explanatory diagram showing the configuration of the magnetizing yoke 114, which has five magnetizing parts 115 provided in the magnetizing yoke 114, positioned in the same position as the magnet mounting holes 5 of the rotor core 3.

[0035] Magnet accommodating holes 116 for accommodating magnets 6 are provided in magnetized portions 115. Magnet accommodating holes 116 are arranged at positions corresponding to magnet mounting holes 5 of rotor core 3. Magnetized portions 115 are further provided with magnetizing coils 117 adjacent to magnet accommodating holes 116. Core yoke portions 118 are formed between magnetized portions 115, and magnetizing coils 117 are wound around core yoke portions 118.

[0036] 6, a communication hole 113b is formed in a case top surface 113a of the magnetizer 111 in correspondence with the magnet accommodating hole 116. A shaft insertion hole 113c, through which the rotor shaft 2 of the rotor 1 is inserted, is also formed in the case top surface 113a. When the rotor 1 is attached to the case top surface 113a of the magnetizer 111 while inserting the rotor shaft 2 into the shaft insertion hole 113c, the magnet mounting hole 5 of the rotor core 3 and the magnet accommodating hole 116 of the magnetizer 111 face each other via the communication hole 113b, and the two are in communication with each other.

[0037] Two rotor positioning protrusions 119a and 119b are further provided on the case top surface 113a of the magnetizer 111. The rotor positioning protrusions 119a and 119b fit into two adjacent grooves 7 on the inner periphery of the magnet mounting hole 5 of the rotor core 3, preventing the rotor core 3 placed on the magnetizer 111 from rotating in the circumferential direction and positioning it in the circumferential direction so that the magnet mounting hole 5 and the magnet accommodating hole 116 communicate with each other.

[0038] Rotor manufacturing apparatus 100 is configured such that magnetizer 111 is arranged in the center, rotor support section 121 and upper magnet holding mechanism 122 are arranged above magnetizer 111, and lower magnet holding mechanism 123 is arranged below rotor support section 121. Rotor support section 121 is a part of rotor manufacturing apparatus 100 that supports and fixes rotor 1 from above, and has rotor support rod 124 that supports the upper end of rotor shaft 2. A fitting holding section 125 is provided at the lower end of rotor support rod 124, and has recess 125a formed therein that fits with the upper end of rotor shaft 2.

[0039] The rotor support part 121 also includes a toggle clamp 126 for moving the rotor support rod 124 up and down and fixing the rotor 1 on the case upper surface 113a of the magnetizer 111. The toggle clamp 126 is installed on a top plate 127 on the upper end side of the rotor manufacturing apparatus 100. The top plate 127 is fixedly supported on a bottom plate 129 by four support columns 128.

[0040] In the rotor manufacturing apparatus 100, the rotor 1, with only the upper magnet holder 8 attached, is placed on the magnetizer 111. Next, the lever 126a of the toggle clamp 126 is slightly operated to move the rotor support rod 124 downward, and the upper end of the rotor shaft 2 is fitted into the recess 125a of the fitting-and-holding portion 125 to temporarily hold the rotor 1. After that, the sleeve 130 is attached to the rotor shaft 2 from the side. The sleeve 130 has a generally U-shaped cross section and is inserted and attached to the rotor shaft 2 through the opening. Then, the lever 126a of the toggle clamp 126 is further operated to move the rotor support rod 124 downward, whereby the sleeve 130 is sandwiched between the upper surface of the magnet holder 8 and the lower surface of the fitting-and-holding portion 125. As a result, the magnet holder 8 is pressed by the sleeve 130, and the rotor 1 is fixedly supported on the magnetizer 111 via the magnet holder 8.

[0041] The magnet upper holding mechanism 122 presses and holds the magnet 6 housed in the magnetizer 111 from above, and has magnet upper pressing pins 131 (pressing members, hereinafter abbreviated as upper pressing pins 131) that come into contact with the upper ends of the magnets 6 inside the magnetizer 111. The upper pressing pins 131 are attached to the lower surface side of an upper movable plate 132 provided above the magnetizer 111. Five upper pressing pins 131 are provided above each magnet accommodating hole 116 in correspondence with the magnet accommodating holes 116 of the magnetizer 111.

[0042] The upper movable plate 132 is provided so as to be movable up and down along a plate guide 133 attached to the underside of the top plate 127. The plate guide 133 is connected to an air cylinder 134 attached to the top plate 127 and is moved up and down by the air cylinder 134. When the upper movable plate 132 is moved downward, the upper holding pin 131 also moves downward and is inserted into the rotor 1 placed on the magnetizer 111. As described above, the magnet holder 8 attached to the rotor core 3 is formed with a pin insertion hole 13, and this pin insertion hole 13 is provided corresponding to the magnet accommodating hole 116. Therefore, the upper holding pin 131 that has moved downward passes through the pin insertion hole 13 and the magnet mounting hole 5 of the rotor core 3 and abuts against the upper end of the magnet 6 accommodated in the magnet accommodating hole 116 of the magnetizer 111. As a result, the magnet 6 in the magnetizer 111 is pressed and held from above.

[0043] The magnet lower holding mechanism 123 supports the magnet 6 housed in the magnetizer 111 from below, and further pushes it upward to insert it from inside the magnetizer 111 into the magnet mounting hole 5 of the rotor core 3. The magnet lower holding mechanism 123 has a magnet lower pressing pin 141 (pressing member, hereinafter abbreviated as lower pressing pin 141) that abuts against the lower end of the magnet 6 inside the magnetizer 111, and a lower movable plate 142 for actuating the lower pressing pin 141 in the up and down direction.

[0044] The lower movable plate 142 is disposed below the magnetizer 111 and is movable in the vertical direction, and the lower presser pins 141 are attached to the upper surface of the lower movable plate 142. Five lower presser pins 141 are also provided corresponding to the magnet accommodating holes 116 of the magnetizer 111. The upper presser pins 131 and the lower presser pins 141 are arranged in a vertical line. The lower movable plate 142 is movable in the vertical direction along a plate guide 143 attached to the lower surface of the magnetizer base 112. The plate guide 143 is connected to an air cylinder 144 attached to the bottom plate 129 and is moved in the vertical direction by the air cylinder 144. A pin guide 145, into which the lower presser pins 141 are inserted and supported, is attached to the center of the magnetizer base 112. The pin guide 145 has five guide holes 146 through which the lower presser pins 141 can be inserted.

[0045] When the lower movable plate 142 is moved upward, the lower holding pin 141 also moves upward and is inserted into the magnet accommodating hole 116 of the magnetizer 111. The lower holding pin 141 is initially positioned so that its upper end abuts against the lower end of the magnet 6 in the magnet accommodating hole 116. As a result, the magnet 6 in the magnetizer 111 is supported from below by the upper end surface of the lower holding pin 141. After the magnetization process of the magnet 6 is completed, when the lower holding pin 141 is moved further upward, the magnet 6 in the magnetizer 111 is pushed upward by the upper end surface of the lower holding pin 141 and fed into the magnet mounting hole 5 of the rotor core 3.

[0046] Next, a method for manufacturing a rotor 1 by magnetizing magnets 6 using such rotor manufacturing apparatus 100 and assembling them into rotor core 3 will be described. Figure 7 is an explanatory diagram showing the rotor manufacturing process using rotor manufacturing apparatus 100. In rotor manufacturing apparatus 100, half of the total ten magnets 6 (five magnets with the same polarity) are magnetized and assembled into rotor core 3 in one process of Figures 7(a) to (e).

[0047] In the rotor manufacturing apparatus 100, the lower press pin 141 is set in advance to a magnet support position where its upper end abuts against the lower end of the magnet 6, and in this state, an unmagnetized magnet 6 is supplied to the magnetizer 111. That is, the magnet 6 is inserted and accommodated in the magnet accommodating hole 116 of the magnetizer 111 through the communication hole 113b in the case upper surface 113a (FIG. 7(a): magnet supply step). At this time, the magnet 6 in the magnet accommodating hole 116 is supported from below by the lower press pin 141.

[0048] Next, the rotor shaft 2 is inserted into the shaft insertion hole 113c on the case top surface 113a, and the rotor 1 is placed on the magnetizer 111 (FIG. 7(b)). The rotor 1 is set in a predetermined rotational position by fitting the rotor positioning protrusions 119a and 119b on the top surface of the magnetizer 111 into the grooves 7 of the rotor core 3. Here, the supply of the magnets 6 and the attachment and detachment of the rotor 1 are performed manually, but these processes can also be automated, which is preferable for mass production. After the rotor 1 is placed on the top surface of the magnetizer 111, the toggle clamp 126 is operated to attach the sleeve 130 and lower the rotor support rod 124. This causes the fitting and holding portion 125 of the rotor support rod 124 to fit into the upper end of the rotor shaft 2 of the rotor 1. Furthermore, the sleeve 130 presses the rotor 1 from above, and the rotor 1 is fixed and supported on the magnetizer 111 (FIG. 7(b): rotor supply and fixation process).

[0049] After the rotor 1 is fixedly supported on the magnetizer 111, the air cylinder 134 is operated to move the upper movable plate 132 downward. This moves the upper pressing pin 131 downward, passing through the pin insertion hole 13 of the magnet holder 8 and into the magnet mounting hole 5 of the rotor core 3 arranged on the magnetizer 111. When the upper pressing pin 131 is then further lowered, the lower end of the upper pressing pin 131 enters the magnet accommodating hole 116 of the magnetizer 111 through the communicating hole 113b and abuts against the upper end of the magnet 6 accommodated therein. As a result, the magnet 6 is pressed from above, and is sandwiched and held between both pins 131 and 141 from above and below, and is accommodated and held in the magnet mounting hole 5 (FIG. 7(c)).

[0050] After the magnets 6 are housed and held in the magnet mounting holes 5, the magnetizer 111 performs a magnetization process on the magnets 6 (FIG. 7(c): magnet housing, holding, and magnetization process). That is, current is supplied to the magnetizing coil 117 in a predetermined direction to magnetize the five magnets 6 with the same polarity (first polarity, for example, clockwise from N to S). At this time, in the rotor manufacturing apparatus 100, the magnetizer 111 can magnetize the entire magnet 6 evenly without causing variations in magnetic flux intensity depending on the location. Therefore, when the magnetized magnets 6 are assembled into the rotor core 3, the magnetic flux of the magnets 6 does not decrease radially inward, and a motor using the rotor 1 can stably obtain the desired output without incurring a decrease in output due to magnetic flux unevenness.

[0051] After magnetizing the magnet 6, the air cylinder 144 is operated to move the lower movable plate 142 upward, thereby moving the lower holding pin 141 upward. At this time, the pressing force of the upper holding pin 131 is set weaker than the upward pressing force of the lower holding pin 141, so the lower holding pin 141 moves upward against the pressing force of the upper holding pin 131. As a result, the magnet 6 in the magnetizer 111 is pushed upward by the lower holding pin 141 while being held upside down, and is inserted directly into the magnet mounting hole 5 of the rotor core 3 (FIG. 7(d): magnetized magnet insertion process). At this time, the upper end of the magnet 6 is held down by the magnet holder 8. That is, the pin insertion hole 13 of the magnet holder 8 is small enough for the upper holding pin 131 to pass through, but is smaller than the cross section of the magnet 6, so the magnet 6 pushed upward comes to a stop when it abuts against the underside of the magnet holder 8.

[0052] The lower holding pin 141 is moved upward, and the magnetized magnet 6 is inserted into the rotor core 3. Then, the air cylinder 134 is operated to move the upper movable plate 132 upward. The upper movable plate 132 is moved to just below the top plate 127, and the upper holding pin 131 is retracted to above the rotor 1. Then, the air cylinder 144 is lowered to lower the lower holding pin 141. After that, the toggle clamp 126 is operated to raise the rotor support rod 124, and the sleeve 130 is removed from the rotor shaft 2, and the rotor support rod 124 is detached from the rotor shaft 2. This frees the rotor 1 on the magnetizer 111, making it possible to remove it from the device (Fig. 7(e): rotor removal process).

[0053] In this way, five magnets 6 are first magnetized and accommodated in the rotor core 3, after which the remaining five magnets 6 are magnetized. That is, as shown in FIG. 7(e), the rotor 1 in a free state after the first half of the process is removed from the magnetizer 111, and as the second half of the process, the steps from FIG. 7(a) onwards are carried out again. In this case, after the magnets 6 are set again in the step of FIG. 7(a), in the step of FIG. 7(b), the rotor 1 is shifted circumferentially by one magnet mounting hole 5 from the rotational position used in the first half of the process, and at that position, the rotor positioning protrusions 119a, 119b are fitted into the grooves 7 and the rotor 1 is set in the magnetizer 111. That is, the rotor 1 is set so that the magnet mounting holes 5 without magnets 6 inserted face and communicate with the magnet accommodating holes 116 of the magnetizer 111.

[0054] Then, in the process shown in Figure 7(c), a current is supplied to the magnetizing coil 117 of the magnetizer 111 in the opposite direction to that in the first half of the process, magnetizing the five magnets 6 with the opposite polarity (second polarity, counterclockwise from N to S in the previous example). The magnets 6 that have been magnetized with this opposite polarity are then inserted into the magnet mounting holes 5 that were left empty in the first half of the process (Figure 7(d)). As a result, the magnets 6 are housed and arranged in the rotor core 3 so that adjacent magnets 6 in the circumferential direction have opposite polarities. The rotor 1 with the ten magnets 6 magnetized and embedded in this way is then removed from the device (Figure 7(e)), and the other magnet holder 8 is attached, etc., to complete the rotor 1.

[0055] The rotor manufacturing apparatus 100 uses a magnetizer 111 in which magnet accommodating holes 116 of a magnetizing section 115 are provided at positions corresponding to the magnet mounting holes 5 of the rotor core 3. The rotor 1 is set in the magnetizer 111 so that the magnet mounting holes 5 and the magnet accommodating holes 116 face each other and communicate with each other. The magnets 6 magnetized by the magnetizing section 115 are inserted and attached to the magnet mounting holes 5 in the same position as they are in the magnet accommodating holes 116. These steps are performed within the apparatus using two holding pins 131, 141 that are movable in the vertical direction and that clamp the magnets 6 from above and below within the magnet mounting holes 5.

[0056] As a result, the magnet 6, which has been uniformly magnetized overall by the magnetizer 111, is assembled into the rotor core 3, and the magnetic flux of the magnet 6 does not decrease radially inward. Therefore, a motor using a rotor 1 manufactured by the rotor manufacturing apparatus 100 can stably obtain the desired output without incurring a decrease in output due to uneven magnetic flux. Furthermore, the magnetization and mounting of the magnet 6 can be performed in one go by the rotor manufacturing apparatus 100, eliminating the need for the difficult and complicated work that was previously required, thereby reducing the number of manufacturing steps for the rotor, reducing defective products, and improving reliability.

[0057] (Embodiment 2) Next, a magnet holder 21 according to a second embodiment of the present invention will be described. Fig. 8 is an explanatory diagram showing the configuration of the magnet holder 21. In the following embodiments and modifications, the same parts and members as those of the rotor 1 and magnet holder 8 of the first embodiment will be given the same reference numerals, and their description will be omitted. The standards for up and down and height are also the same as those in the first embodiment.

[0058] Like the previously described magnet holder 8, the magnet holder 21 is used in the rotor of an inner rotor type IPM motor, and is attached to both ends of the rotor core 3. On the other hand, as shown in Fig. 8, the magnet holder 21 of the second embodiment differs from the previously described magnet holder 8 in that a metal mounting plate 22 (hereinafter simply referred to as plate 22) is insert-molded inside the holder, and by press-fitting this plate 22 onto the rotor shaft 2, the magnet holder 21 is attached and fixed to the rotor core 3 without using a push nut.

[0059] The magnet holder 21 is made of synthetic resin (e.g., PBT) and has a configuration in which a plate 22 is insert-molded into the center of a disk-shaped base portion 23. The magnet holder 21 is tightly fixed to both ends of the rotor core 3 by the base portion 23 so as to cover the rotor core end face 3a. As a result, the magnet 6 inside the rotor core 3 is supported at both axial ends and held in the magnet mounting hole 5, as described above. As a result, the magnet 6 is prevented from coming loose in the axial direction and from flying away from the rotor core 3.

[0060] As described above, the magnet holder 21 has the shaft fixing plate 22 integrally formed with the base portion 23 by resin molding. The plate 22 has a cylindrical shaft fixing portion 22a and a flange portion 22b formed on one end side of the shaft fixing portion 22a. The shaft fixing portion 22a and the flange portion 22b are integrally formed by drawing or the like. The interior of the shaft fixing portion 22a forms a shaft hole 22c through which the rotor shaft 2 is inserted. The plate 22 is fixed to the magnet holder 21 with the flange portion 22b embedded in the base portion 23 of the magnet holder 21. The shaft hole 22c faces and communicates with the axial hole 4 of the rotor core 3 when the core is installed.

[0061] Unlike magnet holder 8 of the first embodiment, magnet holder 21 is fixed to rotor shaft 2 not by a push nut but by this plate 22. That is, by press-fitting shaft fixing portion 22a into rotor shaft 2, magnet holder 21 is fixed to rotor shaft 2 in a state where it is prevented from coming off. This makes it possible to omit the push nut attachment step in rotor 1 of the first embodiment, and to attach and fix magnet holder 21 in a single step of press-fitting plate 22, thereby reducing the number of steps in manufacturing rotor 1.

[0062] Base portion 23 is provided with pin insertion holes 13 (10 in this example) that face magnet mounting holes 5 when the core is attached. Pin insertion holes 13 are provided so as to face the center of magnet 6 housed in magnet mounting hole 5 when the core is attached. A rotor with magnet holder 21 attached can be magnetized and manufactured by rotor manufacturing apparatus 100 described above, similar to rotor 1 of embodiment 1, and pin insertion holes 13 are used in the rotor manufacturing process described above.

[0063] One surface of the base portion 23 is provided with protrusions 14 that are inserted into the grooves 7 of the rotor core 3. Ten protrusions 14 are provided radially inside the pin insertion holes 13, and when the core is attached, the protrusion outer surfaces 14a and the magnet inner surface 6a face each other and come into contact with each other with a slight clearance. Furthermore, in the magnet holder 21, one surface of the base portion 23 is provided with a core contact portion 25 that protrudes and comes into contact with the rotor core end surface 3a when the core is attached. Unlike the magnet holder 8 of the first embodiment, the core contact portion 25 is formed in two separate regions along the radial direction of the base portion 23. That is, as shown in FIG. 8, the core contact portion 25 is composed of a first core contact portion 25a provided on the radially outer side and a rib-shaped second core contact portion 25b provided on the radially inner side.

[0064] The first core contact portions 25a are provided at ten equal intervals along the circumferential direction and are configured to face the magnet mounting holes 5 of the rotor core 3 when the core is installed. A pin insertion hole 13 used in the rotor manufacturing apparatus 100 is provided in the center of each first core contact portion 25a. The second core contact portions 25b are provided at positions along the periphery of the inner circumferential hole 24 of the base portion 24. An inner circumferential wall 26 is provided around the entire periphery of the inner circumferential hole 24, and the second core contact portions 25b are provided to protrude from this inner circumferential wall 26. The second core contact portions 25b are provided at ten equal intervals along the circumferential direction at intermediate positions between adjacent protrusions 14.

[0065] One of the second core contact portions 25b extends radially and serves as a gate rib 28. This configuration allows resin to flow evenly to both axially opposite portions of the plate 22 when insert-molding the plate 22. As shown in FIG. 9(b), when molding is performed using a single gate from the back side of the base portion 23 (the axially opposite side from the one surface side), if the second core contact portion 25b is short, the resin flow path 29 from the gate G to the one surface side on which the protrusion 14 is erected becomes small. Therefore, with the configuration shown in FIG. 9(b), the resin flow to the one surface side may be slowed, resulting in a short (low height) protrusion 14. Therefore, in the magnet holder 21, the second core contact portion 25b facing the gate G is extended radially to serve as a gate rib 28, thereby enlarging the resin flow path 29 to the one surface side as shown in FIG. 9(a). This ensures sufficient resin flow to the one surface side, and the protrusion 14 is formed to the specified height without any problems.

[0066] The base portion 23 has a recess 27 in its entirety, except for the first core contact portion 25a, the inner peripheral wall 26, and the second core contact portion 25b. The top surfaces of the first and second core contact portions 25a and 25b are set at the same height from the bottom of the recess 27. That is, one side of the base portion 23 is provided with core contact portions 25, with the first core contact portion 25a on the outer side and the second core contact portion 25b on the inner side, at the same height. Therefore, when the core is attached, the top surfaces of the first core contact portion 25a and the second core contact portion 25b, which are on the same plane, come into direct contact with the rotor core end face 3a. As a result, the core contact portion 25 makes surface contact with the rotor core end face 3a along the radial direction from the outer periphery of the base portion 23 to the position of the inner peripheral hole 24. This stabilizes the contact surface between the rotor core 3 and the magnet holder 21, improving the positioning accuracy of the magnet 6. Furthermore, the load applied when the magnet holder 21 is press-fitted can be supported by the entire radial surface.

[0067] As with magnet holder 8 of embodiment 1, curved surface portion 14b is provided at the base of protrusion 14 from the perspective of preventing stress concentration and moldability. For this reason, also in magnet holder 21, if protrusion 14 were to rise directly from the bottom surface of recess 27, there is a risk that the end of magnet 6 would ride up onto curved surface portion 14b when the core is attached, causing core contact portion 25 to lift off rotor core end face 3a. In contrast, in magnet holder 21, protrusion 14 rises from the bottom surface of recess 27 and the upper surface of inner circumferential wall 26, which are lower than first and second core contact portions 25a, 25b, and the upper end position of curved surface portion 14b is set lower than the upper surfaces of first and second core contact portions 25a, 25b.

[0068] Therefore, when the core is attached, the curved surface portion 14b fits into the recess 27, and a gap is formed between the base of the protrusion 14 and the rotor core end face 3a. In other words, the magnet holder 21 is also designed so that the curved surface portion 14b and the end of the magnet 6 do not come into contact when the core is attached. As a result, even in the rotor 1 using the magnet holder 21, the core contact portion 25 comes into contact with the rotor core end face 3a without floating up when the core is attached, and the magnet holder 8 is attached to the rotor core 3 in a tight fit.

[0069] Such magnet holders 21 are also attached to both ends of the rotor core 3 by inserting the protrusions 14 into the grooves 7 of the rotor core 3. As a result, both ends of the magnet mounting hole 5 of the rotor core 3 are covered by the core contact portions 25 of the magnet holder 21, restricting axial movement of the magnet 6. In other words, the magnet 6 is prevented from falling out and scattering. Furthermore, when the core is attached, the protrusion outer surfaces 14a and the magnet inner surfaces 6a face and contact each other, restricting radial movement of the magnet 6. At this time, the movement of the radially outer surface of the magnet 6 is restricted by the outer peripheral wall of the magnet mounting hole 5. As a result, the magnet 6 is positioned radially within the magnet mounting hole 5, and it is possible to prevent the magnet 6 from tipping over toward the grooves 7.

[0070] Furthermore, since the periphery of the protrusion 14 is a recess 27, the magnet holder 21 does not lift off the rotor core end face 3a when the core is attached. Furthermore, since the core contact portion 25 includes a first core contact portion 25a on the outer periphery and a second core contact portion 25b near the inner peripheral hole 24, the magnet holder 21 makes surface contact with the rotor core end face 3a at both the outer and inner periphery along the radial direction. As a result, the contact surface between the rotor core 3 and the magnet holder 21 is stabilized, ensuring the positioning accuracy of the magnet 6 by the protrusion 14 and improving the positioning accuracy. As mentioned above, the magnet holder 21 also has a pin insertion hole 13, so a rotor equipped with the magnet holder 21 can be magnetized and manufactured using a rotor manufacturing apparatus 100 as shown in FIG. 4.

[0071] In this way, by attaching the magnet holders 8, 21 to both ends of the rotor core 3, it is possible to accurately position the magnet 6 and prevent it from coming loose in the axial direction. This makes it possible to prevent the magnet from scattering from the rotor core 3 by attaching a resin-molded product, which is relatively easy to manufacture. Furthermore, by attaching the magnet holders 8, 21, the magnet 6 can be positioned and fixed within the rotor core 3, so the magnet 6 can be held and fixed within the rotor 1 by magnetic force alone. This eliminates the need to resin-mold the rotor or use adhesive or spring fixing to prevent the magnet from scattering. Compared to using molding, etc., this reduces the production man-hours and number of parts, thereby reducing product costs. Furthermore, by providing the magnet holders 8, 21 with pin insertion holes 13 used in the rotor manufacturing process, the rotor 1 can be assembled on an automated line, further reducing production costs.

[0072] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit and scope of the present invention. For example, the configurations of magnet holders 8 and 21 in embodiments 1 and 2 are interchangeable as appropriate, and as shown in Fig. 10, plate 22 may be provided on magnet holder 8 in embodiment 1 (magnet holder 31: variant 1). That is, the basic configuration of magnet holder 8, such as protrusions 14, recesses 16, and core contact portion 15, may remain the same, and a press-fit mounting method using plate 22 may be used. In this case, magnet holder 31 is mounted and fixed to rotor core 3 by press-fitting plate 22 into rotor shaft 2 without using a push nut.

[0073] Furthermore, contrary to the first modification, as shown in FIG. 11 , the plate 22 may be omitted from the magnet holder 21 of the second embodiment, and a push-nut mounting configuration may be adopted (magnet holder 32: modification 2). That is, the basic configuration of the magnet holder 21, such as the protrusions 14, recesses 27, and core contact portions 25, may remain the same, but the plate 22 may be omitted from the magnet holder 21. In this case, the magnet holder 32 is attached to the rotor core 3 and fixed to the rotor shaft 2 with a push nut (see FIG. 2 ). The magnet holder 32 has a shaft hole 12 formed in its center, and an inner circumferential wall 26 provided along its periphery 12a. The second core contact portion 25b is provided from the inner circumferential wall 26 to the position of the protrusions 14, extending radially beyond the magnet holder 21. In the case of the magnet holder 32, the plate 22 is not insert-molded, but a gate rib 28 is also provided here in consideration of the resin flowability on one side. Furthermore, since the plate is omitted, the component cost of the magnet holder itself is reduced.

[0074] Furthermore, the magnet holder is fixed to the rotor shaft using push nuts in the first embodiment and press-fitting a plate in the second embodiment, but both can be used together (press-fitting + push nuts). It is also possible to use adhesives or retaining rings such as E-rings and C-rings.

[0075] Meanwhile, in the rotor manufacturing apparatus described in the first embodiment, ten magnets 6 are magnetized and attached using one rotor manufacturing apparatus 100 by varying the rotor setting position and the polarity of the magnetizing coil 117. However, during mass production, two rotor manufacturing apparatuses 100 with different rotor setting positions and magnetizing coil polarity may be used, or an apparatus equipped with two magnetizers 111 may be used. When two apparatuses are used, each rotor manufacturing apparatus 100 is provided with a magnetizer 111 (first and second magnetizers) that magnetize a set of five magnets 6 with different polarities. After the magnetization and attachment process (corresponding to the first half of the embodiment) is performed by one apparatus, the other apparatus performs the respective processes (corresponding to the second half of the embodiment). Furthermore, in the case of an apparatus equipped with two magnetizers 111, two of each mechanism of the rotor manufacturing apparatus 100 are arranged in one apparatus.

[0076] Furthermore, although the embodiment is configured such that the rotor core and magnets are manually set in the apparatus, as described above, automatic setting is also possible during mass production, etc. In this case, in a process using one rotor manufacturing apparatus 100, the rotor or magnetizer may be automatically rotated and set in the rotor supply and fixation process in the latter half of the process, so that the empty magnet mounting hole on the rotor faces the magnet accommodating hole on the magnetizer, and the subsequent process may be carried out. Furthermore, even in a process using two rotor manufacturing apparatuses 100, automating the setting of the rotor core and magnets can improve production efficiency during mass production, etc. [Industrial Applicability]

[0077] The present invention is applied to the rotor of an IPM motor used as the drive source of an electric oil pump, for example, but can also be applied to rotors of various IPM motors used in electric power steering devices, electric brake systems, hybrid cars, electric vehicles, etc. Furthermore, the magnet holder and rotor of the present invention can be applied not only to motors related to automobiles, but also to motors for other electric machines and devices such as home appliances and industrial machinery. [Explanation of symbols]

[0078] 1 rotor 2 rotor shaft 3 Rotor core 3a Axial end face 4 shaft holes 5 Magnet mounting hole 6. Magnets 6a Radial inner surface 7 Groove 8 Magnet holder 9 Push Nut 11 Base 12 Shaft hole 12a Shaft hole periphery 13 Pin insertion hole 14 Protrusion 14a Radial outer surface 14b Curved part 15 Core contact part (first core contact part) 16 Recess 16a Bottom 17 Peripheral wall (contact area with second core) 21 Magnet holder 22 Mounting plate 22a Shaft fixing part 22b Flange part 22c shaft hole 23 Base 24 Inner hole 25 Core contact area 25a First core contact part 25b Second core contact part 26 Inner wall 27 Recess 28 Gate Rib 29 Resin flow path 31 Magnet holder 32 Magnet holder 100 Rotor manufacturing equipment 111 Magnetizer 112 Magnetizer Base 113 cases 113a Case top 113b Communication hole 113c Shaft insertion hole 114 Magnetizing yoke 115 Magnetized part 116 Magnet storage hole 117 Magnetizing coil 118 Iron core yoke 119a, 119b Rotor positioning protrusions 121 rotor support 122 Magnet upper holding mechanism 123 Lower magnet holding mechanism 124 rotor support rod 125 Fitting retention part 126 Toggle Clamp 126a Lever 127 Top Plate 128 Post 129 Bottom Plate 130 sleeve 131 Magnet upper holding pin (holding member) 132 Upper movable plate 133 Plate Guide 134 Air Cylinder 141 Magnet lower holding pin (holding member) 142 Lower movable plate 143 Plate Guide 144 Air Cylinder 145 Pin Guide 146 Guide hole G Gate

Claims

1. A magnet holder to be attached to a rotor for an electric motor, the rotor having a rotor shaft, a rotor core attached to the rotor shaft and having a plurality of magnet attachment holes formed along a circumferential direction, and magnets disposed in the magnet attachment holes, the magnet holder is attached to an axial end surface of the rotor core, a base portion formed in a disk shape; a core contact portion provided on one surface side of the base portion and in contact with the end surface of the rotor core; a protrusion provided on the one surface, extending axially and inserted into the magnet mounting hole.

2. 2. The magnet holder according to claim 1, the core contact portion covers an axial end of the magnet mounting hole and restricts axial movement of the magnet; The magnet holder is characterized in that the protrusion abuts against a radial end face of the magnet within the magnet mounting hole, thereby restricting radial movement of the magnet.

3. 2. The magnet holder according to claim 1, A magnet holder characterized in that the core contact portion comprises a first core contact portion provided on the outer periphery of the base portion, and a second core contact portion provided radially inside the first core contact portion, the upper surface of which is set at the same height as the upper surface of the first core contact portion.

4. 4. The magnet holder according to claim 3, A magnet holder, characterized in that the first core contact portion and the second core contact portion are integrally formed.

5. 4. The magnet holder according to claim 3, A magnet holder, characterized in that the first core contact portion and the second core contact portion are provided separately.

6. The magnet holder according to any one of claims 1 to 5, a recessed portion having a bottom surface lower than an upper surface of the core contact portion is provided on one surface of the base portion; the protrusion is provided to protrude from the bottom surface of the recess, and a curved surface portion rising from the bottom surface of the recess is formed at the base of the protrusion; A magnet holder characterized in that the height from the bottom surface of the recess to the top surface of the core contact portion is higher than the height from the bottom surface of the recess to the top end of the curved portion, and the top end of the curved portion is positioned lower than the top surface of the core contact portion.

7. 2. The magnet holder according to claim 1, the base portion is provided radially outward of the protrusion portion and has a through hole that penetrates the base portion in the axial direction, The magnet holder is characterized in that the through hole opens to face the magnet in the magnet mounting hole when the magnet holder is attached to the end surface of the rotor core.

8. A rotor for an electric motor includes: a rotor shaft; a rotor core attached to the rotor shaft and having a plurality of magnet mounting holes formed along a circumferential direction; and magnets disposed in the magnet mounting holes, the rotor has a magnet holder attached to an axial end surface of the rotor core, The magnet holder is a rotor for an electric motor, characterized in that it has a base portion formed in a circular plate shape, a core contact portion provided on one side of the base portion and contacting the end face of the rotor core, and a protrusion portion protruding from the one side, extending axially, and inserted into the magnet mounting hole.

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