Embedded magnet type rotor and rotary electric machine

Abstract

According to the embodiment, the buried magnet type rotor (100) has a rotor shaft, a rotor core (120) formed with a plurality of permanent magnet receiving spaces (121), and a flat plate-shaped permanent magnet (130). The permanent magnet receiving space (121) further expands to the radially outer side from the range where the magnet holding outer side protrusion (123b) holds the permanent magnet (130), and has a communication opening (128) that communicates with the gap space (15). The communication opening (128) is formed by being sandwiched by two small pieces (127a, 127b). In a cross section perpendicular to the rotation axis direction, the thickness in the radial direction of the two small pieces (127a, 127b) and the width in the circumferential direction of the communication opening (128) are formed in the following size relationship: fragments generated due to breakage of the permanent magnet (130) do not protrude from the communication opening (128) to contact the stator.

Description

Technical Field

[0001] This invention relates to an embedded magnet rotor and a rotary electric motor having the same. Background Technology

[0002] In a rotating electric motor with an embedded magnet rotor, a through-hole extending axially is formed in the region near the radially outer side of the rotor core to house the permanent magnet. Typically, this through-hole not only houses the permanent magnet but also has a portion of space on its radially outer side. This radially outer portion of space serves as a magnetically insulating groove to suppress the passage of magnetic flux.

[0003] In many cases, a top bridge, which is part of the rotor core, exists between the radially outer portion of the space and the outer surface of the rotor core in order to ensure the structural strength of the rotor core.

[0004] The top bridge becomes a magnetic flux pathway, or magnetic circuit. The magnetic flux passing through this magnetic circuit remains only within the rotor, becoming leakage flux that does not link with the stator side, resulting in a reduction in the torque efficiency of the rotating motor.

[0005] Against this backdrop, there are examples of rotors that use a method of removing the top bridge to connect the aforementioned radially outer portion of the space with the outer space of the rotor core (the gap space between the rotor and the stator).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 5447418 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] In rotors with embedded magnets and no top bridge, as described above, leakage flux can be reduced. However, countermeasures are needed to address situations where magnets break under abnormal conditions, such as abnormal increases in rotational speed. Specifically, in the event of magnet fragments, they may fly out through the radially outer portion of the space into the gap space outside the rotor core.

[0011] The following problem exists: if fragments of the magnet fly out into the gap space, they may get stuck between the rotor and the stator, causing the rotor to lock and damaging the outer surface of the rotor or the inner surface of the stator.

[0012] The purpose of this invention is to provide an embedded magnet rotor and rotary motor in which the fragments will not protrude into the gap space even if the permanent magnet is damaged.

[0013] Methods for solving problems

[0014] To achieve the above objectives, the embedded magnet rotor of the present invention comprises: a rotor shaft extending along the rotation axis direction; a rotor core disposed radially outside the rotor shaft, wherein a plurality of permanent magnet storage spaces are formed circumferentially spaced apart near the radially outer side; and plate-shaped permanent magnets respectively housed in the plurality of permanent magnet storage spaces; the embedded magnet rotor is characterized in that the permanent magnet storage space extends radially outward from the area where the permanent magnet is held by the magnet holding outer protrusion formed in the rotor core, and has a communication opening communicating with the gap space between the embedded magnet rotor and the stator disposed radially outside the embedded magnet rotor, the communication opening being formed by clamping two circumferentially extending small pieces that are part of the rotor core, and in a cross section perpendicular to the rotation axis direction, the radial thickness of the two small pieces and the circumferential width of the communication opening are sized such that fragments generated in the event of permanent magnet damage will not protrude from the communication opening and contact the stator.

[0015] Furthermore, the rotary electric motor according to the embodiments of the present invention is characterized by comprising: the above-described embedded magnet type rotor, the stator, and two bearings that rotatably support the rotor shaft. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view showing the structure of the rotary electric machine according to the embodiment.

[0017] Figure 2 This is a partial cross-sectional view showing the structure of one magnetic pole portion of the embedded magnet rotor according to the embodiment.

[0018] Figure 3 This is a partial cross-sectional view showing an example of damage to a permanent magnet in an embedded magnet rotor according to an embodiment.

[0019] Figure 4 This is a partial cross-sectional view showing the state of fragments in an example of damage to a permanent magnet in an embedded magnet rotor according to an embodiment.

[0020] Figure 5 This describes the state of fragments in an example of damage to a permanent magnet in an embedded magnet rotor according to an embodiment. Figure 4 A magnified view of the vicinity of the connecting opening. Detailed Implementation

[0021] Hereinafter, embodiments of the embedded magnet type rotor and rotary motor of the present invention will be described with reference to the accompanying drawings. Here, the same reference numerals are used to denote the same or similar parts, and repeated descriptions are omitted.

[0022] Figure 1This is a cross-sectional view showing the structure of the rotary motor 200 according to the embodiment.

[0023] The rotary motor 200 includes an embedded magnet rotor 100, a cylindrical stator 10, and two bearings (not shown). The embedded magnet rotor 100 has a rotor shaft 110 extending along the rotation axis, a rotor core 120 mounted on the rotor shaft 110, and a plurality of permanent magnets 130. The cylindrical stator 10 is arranged radially outside the rotor core 120, surrounding it with a gap space 15. The two bearings (not shown) rotatably support the rotor shaft 110.

[0024] The rotor core 120 has a plurality of electromagnetic steel plates 120a stacked along the rotation axis. Each electromagnetic steel plate 120a has a punched portion for the rotor shaft 110 to pass through and a punched portion for the permanent magnet 130 to pass through. By stacking the plurality of electromagnetic steel plates 120a, through holes extending along the rotation axis are formed in the rotor core 120. Furthermore, in Figure 1 The example shown is based on the case where the rotor core 120 has an electromagnetic steel plate 120a, but it is not limited to this case. It can also be applied to block rotors where the rotor shaft and rotor core are integrated.

[0025] The permanent magnet 130 is flat. The two permanent magnet storage spaces 121, each housing one of the two permanent magnets 130, are arranged in a V-shape, convex radially inward, corresponding to each magnetic pole. Furthermore, in... Figure 1 The example shown is that the permanent magnet 130 is configured in a V shape, but it is not limited to this case. It can be applied to configurations with fragmentation problems.

[0026] On the inner circumferential side of the stator 10, a plurality of stator teeth 11 for winding stator windings (not shown) are formed at intervals along the circumferential direction.

[0027] Here, the radial width of the gap space 15 is defined as δ. That is, the radial width δ of the gap space 15 is the interval between the outer peripheral surface of the rotor core 120 and the inner peripheral envelope surface of the stator 10, i.e., the top of the radially inner side of the stator teeth 11.

[0028] Figure 2 This is a partial cross-sectional view showing the structure of a magnetic pole portion of the embedded magnet rotor 100 according to the embodiment.

[0029] The region sandwiched between the radially inner ends of the two V-shaped permanent magnet housing spaces 121 functions as a central bridge 126 in the rotor core 120, connecting the radially outer and radially inner portions of the two permanent magnet housing spaces 121. Furthermore, in Figure 2In the case of a central magnetic isolation groove 125 formed in the center of the central bridge 126, it is also possible that it is not present.

[0030] In each permanent magnet storage space 121, in addition to the part that stores the permanent magnet 130, there is also a part of space located radially outside the permanent magnet 130.

[0031] Specifically, within the permanent magnet storage space 121, there exists an outer portion space 122, which is located radially outward from the permanent magnet 130, i.e., on the side furthest from the central bridge 126. The outer portion space 122 is connected to the gap space 15 via a connecting opening 128.

[0032] The connecting opening 128 is formed to be held by two small pieces 127a and 127b, which form part of the outer peripheral surface of the rotor core 120.

[0033] In the permanent magnet housing space 121, between the permanent magnet 130 and the outer portion space 122, a convex magnet retaining outer protrusion 123b, which is part of the rotor core 120, is formed to counteract the centrifugal force of the permanent magnet 130 during the rotation of the embedded magnet rotor 100. The magnet retaining outer protrusion 123b is formed on the radially inner surface of the permanent magnet housing space 121.

[0034] Additionally, within the permanent magnet storage space 121, there exists an inner portion space 124, which is located radially inward from the permanent magnet 130, i.e., closer to the central bridge 126.

[0035] Figure 3 This is a partial cross-sectional view showing an example of damage to a permanent magnet 130 of the embedded magnet rotor 100 in the embodiment.

[0036] During the rotation of the embedded magnet rotor 100, the centrifugal force applied to the permanent magnet 130 is borne by the radial outer wall 121a of the permanent magnet housing space 121 and the magnet retaining outer protrusion 123b.

[0037] There are no protrusions on the radially outer sidewall 121a that is in contact with the radially outer sidewall 130a of the permanent magnet 130.

[0038] Here, as Figure 3 As shown, the distance between the front end of the outer protrusion 123b and the radial outer wall 121a of the magnet is set to H.

[0039] On the other hand, regarding the radially outer end face 130b of the permanent magnet 130, the portion near the radially inner side face 130c contacts the magnet retaining outer protrusion 123b, while the remaining portion, i.e., the portion along length H, does not have any contact. Therefore, stress concentration occurs at the front contact portion 123p of the radially outer end face 130b of the permanent magnet 130, where it contacts the front end of the magnet retaining outer protrusion 123b.

[0040] Therefore, the defects in the permanent magnet 130 are more likely to originate from the front contact portion 123p. Furthermore, the portion of the permanent magnet 130 that is held against the magnet retaining outer protrusion 123b on the radially outer end face 130b will experience compressive stress, while the portion not held against the magnet retaining outer protrusion 123b will be subjected to a radially outward load due to centrifugal force. As a result, in the defects originating from the front contact portion 123p, a tensile stress component will be generated along the radially outer end face 130b of the permanent magnet 130. This tensile stress component is the reason why the defects originating from the front contact portion 123p develop into cracks 131 towards the inner side of the permanent magnet 130.

[0041] Due to these relationships, the crack 131 develops towards the radially inner side of the radially outer corner 132c of the permanent magnet 130.

[0042] Figure 4 This is a partial cross-sectional view showing the state of fragment 132 in an example of damage to a permanent magnet 130 of the embedded magnet rotor 100 of the embodiment.

[0043] Figure 3 The crack 131 shown penetrates the permanent magnet 130, thereby producing a fragment 132. As described above, because the crack 131 extends radially inward toward the radially outer corner 132c of the permanent magnet 130, the radially outer corner 132c will remain on the fragment 132.

[0044] In addition, in the embedded magnet rotor 100, it is generally believed that the fragment 132 moves in a radially outer corner 132c state due to the direction of the centrifugal force applied to the fragment 132.

[0045] That is, it is generally considered to be in the following state: part of the radially outer end face 130b is constrained by the small piece 127a, part of the radially outer side face 130a is constrained by the small piece 127b, and the radially outer corner 132c exists within the connecting opening 128.

[0046] Figure 5 This describes the state of fragment 132 in an example of damage to a permanent magnet 130 of the embedded magnet rotor 100 in this embodiment. Figure 4 Enlarged view of the area near the connecting opening 128.

[0047] Fragment 132 protrudes from the outer portion of space 122 into the connecting opening 128.

[0048] It is the state in which the radially outer side surface 130a of fragment 132 contacts the inner corner of small piece 127b at P1 and the radially outer end face 130b of fragment 132 contacts the inner corner of small piece 127a at P2.

[0049] Perpendicular to the extension direction of the rotation axis of rotor shaft 110 Figure 5 In the cross-section shown, the radially outer corner 132c of fragment 132, i.e., points Pt, P1, and P2, form a right triangle. Therefore, the trajectory of point Pt is... Figure 5 The interval between points P1 and P2, i.e. the width L of the connecting opening 128, is a semicircle of diameter. Here, half of the diameter L is set as the radius r.

[0050] Furthermore, considering manufacturing constraints, the width L of the connecting opening 128 needs to be more than twice the thickness T of the electromagnetic steel plate 120a.

[0051] As a result, when the radius r is smaller than the thickness W of the small pieces 127a and 127b, the radially outer side 130a of the fragment 132 will not protrude from the outer peripheral surface of the embedded magnet rotor 100.

[0052] Based on the above, the embedded magnet rotor 100 of this embodiment satisfies the following conditions (1) and (2) for the outer portion space 122 of the permanent magnet storage space 121.

[0053] 2·T=<L<H (1)

[0054] L / 2-W<δ (2)

[0055] Here, H is Figure 3 The magnet shown maintains the distance between the front end of the outer protrusion 123b and the radial outer wall 121a. L is the width of the connecting opening, W is the radial thickness of the two small pieces, T is the thickness of the electromagnet plate 120a, and δ is the radial width of the gap space 15. Furthermore, "X=<Y" indicates that X is less than or equal to Y.

[0056] Furthermore, when fragment 132 is tilted relative to the rotation axis, Figure 5 In the middle, because the radially outer corner 132c of fragment 132 is in Figure 5 The angle in the top view is greater than 90 degrees, so it will have more leeway to satisfy the above (1).

[0057] That is, because the embedded magnet rotor 100 of this embodiment satisfies the conditions of formula (1) and formula (2), the fragments 132 of the permanent magnet 130 will not protrude into the gap space 15.

[0058] As described above, according to this embodiment, it is possible to provide an embedded magnet rotor and rotary motor in which the fragments will not protrude into the gap space even if the permanent magnet is damaged.

[0059] [Other Implementation Methods]

[0060] The embodiments of the present invention have been described above, but these embodiments are provided as examples and are not intended to limit the scope of the invention. Furthermore, features of each embodiment can be combined. Moreover, the embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The embodiments and their variations are included in the scope and spirit of the invention, and are also included within the scope of the invention as described in the claims and its equivalents.

[0061] Explanation of reference numerals in the attached figures

[0062] 10…Stator

[0063] 11…Stator teeth

[0064] 15…gap space

[0065] 100… Embedded magnet type rotor

[0066] 110…rotor shaft

[0067] 120… rotor core

[0068] 120a… Electromagnetic steel plate

[0069] 121…Permanent magnet storage space

[0070] 121a…Radial outer wall

[0071] 122…Outer Space

[0072] 123a… The magnet maintains its inner protrusion.

[0073] 123b… The magnet maintains its outer protrusion.

[0074] 123p…Front-end contact section

[0075] 124…Inner Part Space

[0076] 125…Central magnetic shielding groove

[0077] 126…Central Bridge

[0078] 127a, 127b... small pieces

[0079] 128…connecting openings

[0080] 130…permanent magnet

[0081] 130a…Radial outer side

[0082] 130b…Radial outer end face

[0083] 130c…radial inner side surface

[0084] 131… Crack

[0085] 132… fragments

[0086] 132c…Radial outer corner

[0087] 200… Rotary motor

Claims

1. A rotor with embedded magnets, comprising: The rotor shaft extends along the direction of rotation. A rotor core, disposed radially outside the rotor shaft, has multiple permanent magnet housing spaces formed circumferentially spaced near its radially outer side; and Flat permanent magnets are respectively housed in the plurality of permanent magnet storage spaces; The embedded magnet type rotor is characterized by the following: The permanent magnet housing space extends radially outward from the area where the permanent magnet is held by the magnet retaining protrusion formed on the outer side of the rotor core, and has a communicating opening that communicates with the gap space between the embedded magnet rotor and the stator disposed on the radially outer side of the embedded magnet rotor. The connecting opening is formed by clamping two small, circumferentially extending plates that are part of the rotor core. In a cross-section perpendicular to the direction of the rotation axis, the radial thickness of the two small pieces and the circumferential width of the connecting opening are sized such that fragments generated in the event of permanent magnet failure will not protrude from the connecting opening and contact the stator. The rotor core has multiple stacked electromagnetic steel plates. The dimensional relationship satisfies the following equations (1) and (2): 2·T=<L<H (1) L / 2-W<δ (2) Here, H is the distance between the front end of the outer protrusion of the magnet holding the outer protrusion and the radial outer wall of the permanent magnet receiving space opposite to the outer protrusion of the magnet holding the outer protrusion, L is the width of the connecting opening, W is the radial thickness of the two small pieces, T is the plate thickness of the electromagnetic steel plate, δ is the radial width of the gap space, and "X=<Y" means that X is less than or equal to Y.

2. The embedded magnet rotor according to claim 1, characterized in that, The multiple permanent magnet storage spaces are arranged in a V-shape protruding radially inward in each magnetic pole section, with two of the permanent magnet storage spaces forming a group.

3. A rotary electric motor, characterized in that, have: The embedded magnet rotor as described in claim 1 or 2; and The stator is disposed on the radially outer side of the rotor core.

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