electric motor

Abstract

In an electric motor in which the stator core and coils are covered with molded resin, the present invention provides an electric motor that can suppress the inward tilting of the flange portion and suppress stress concentration around the recess on the resin side. [Solution] An electric motor according to one embodiment of the present invention comprises a stator core having an annular yoke portion and a plurality of teeth portions, an insulator, a coil, a resin outer shell formed to cover the stator core and the coil, and a rotor. The insulator has a winding drum portion formed along the teeth portions and a flange portion projecting from the radially inner end of the winding drum portion toward the opposite side from the stator core. The resin outer shell has a flange covering portion that covers the radially inner surface of the flange portion. The flange covering portion has a recess that is recessed toward the flange portion, and the flange portion has a convex portion that projects radially inward. The convex portion of the flange portion is formed at a position that overlaps radially with the recess of the flange covering portion.

Description

Technical Field

[0001] The present invention relates to an electric motor provided with a stator having an insulator.

Background Art

[0002] Conventional electric motors include an inner rotor type electric motor in which a rotor having a permanent magnet is rotatably disposed inside a stator that generates a rotating magnetic field. This type of electric motor includes, for example, a brushless DC motor for rotationally driving a blower fan mounted in an indoor unit of an air conditioner.

[0003] For example, Patent Document 1 describes a stator having a cylindrical stator core, an annular upper insulator attached to the upper end face of the stator core, an annular lower insulator attached to the lower end face of the stator core, and a winding (coil) wound around the stator core via the upper insulator and the lower insulator, and a rotor disposed inside the stator. The upper insulator has an annular flange portion that abuts against the upper end face of the stator core, a plurality of winding barrels that project radially inward from the flange portion and abut against the teeth portion of the stator core, and a flange portion that projects upward from the winding barrel portion to prevent the winding (coil) from coming off.

[0004] However, in the manufacturing process of the electric motor described in Patent Document 1, the stator core and the coil are coated with a mold resin by injection molding. In this resin molding process, there is a risk that the flange portion of the insulator will fall inward in diameter due to the pressure when the mold resin is injected into the mold. And when the flange portion falls, the flange portion is exposed from the mold resin, and there is a risk that the insulation performance between the coil and the stator core will deteriorate.

[0005] In contrast, a configuration (Patent Document 2) is described in which a projection is provided on the injection molding die that protrudes toward the flange side of the insulator, thereby preventing the flange from collapsing toward the inner circumference due to the pressure when the mold resin is injected into the die. In this method, after resin molding, a recess is formed in the mold resin that is recessed toward the outer circumference at a position corresponding to the flange. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2018-139463 [Patent Document 2] Japanese Patent Publication No. 2015-154514 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, in the invention described in Patent Document 2, if the protrusion amount of the mold is increased, a large recess will be formed on the resin side at the corresponding position, and the change in resin thickness around this recess will be large, which may cause stress to concentrate around the recess that occurs in the resin after resin molding. On the other hand, in the invention described in Patent Document 2, if the protrusion amount of the mold is reduced, stress concentration around the recess can be suppressed, but there is a risk that the effect of preventing the flange from tilting inward will be reduced.

[0008] In other words, there was a problem in that it was not possible to achieve both "preventing the flange from tilting inward" and "preventing stress concentration around the recess on the resin side."

[0009] In view of the above circumstances, the object of the present invention is to provide an electric motor in which the stator core and coil are covered with molded resin, which can suppress the flange portion from tilting inward and suppress the concentration of stress around the recess on the resin side. [Means for solving the problem]

[0010] To achieve the above objective, an electric motor according to one embodiment of the present invention comprises a stator core having an annular yoke portion and a plurality of teeth portions projecting radially inward from the inner circumferential surface of the yoke portion, an insulator disposed at the axial end of the stator core, a coil wound around the teeth portion via the insulator, a resin outer shell formed to cover the stator core and the coil, and a rotor disposed radially inward of the stator core. The insulator has a winding drum portion formed along the teeth portion, and a flange portion that protrudes from the radially inner end of the winding drum portion toward the opposite side of the stator core in the axial direction, The above resin outer shell has a flange covering portion that covers the radially inner surface of the flange portion, The flange covering portion has a recess that is recessed toward the flange portion side, The flange portion has a convex portion that protrudes inward in the radial direction, The convex portion of the flange is formed at a position that overlaps with the concave portion of the flange covering in the radial direction.

[0011] According to the above-described electric motor, the insulator has a flange portion that protrudes from the radially inner end of the winding drum portion toward the opposite side of the stator core in the axial direction, and the flange portion has a convex portion that protrudes radially toward the inside, and the convex portion of the flange portion is formed at a position that overlaps radially with the recess of the flange covering portion. As a result, even if the size of the recess of the flange covering portion is reduced, the distance between the bottom surface of the recess of the flange covering portion and the convex portion on the flange portion side can be reduced, so that the effect of suppressing the tilting of the flange portion can be sufficiently ensured. In addition, since it is possible to reduce the size of the recess formed in the flange covering portion, stress concentration due to a large recess can be suppressed.

[0012] The radially inner end of the teeth portion may be located radially inward from the convex portion of the flange portion.

[0013] The concave portion of the flange covering portion may have inclined surfaces that incline to connect the inner peripheral surface of the flange covering portion and the bottom of the concave portion at both ends in the circumferential direction.

[0014] The convex portion of the flange portion has a first convex portion disposed on one side in the circumferential direction with respect to the center in the circumferential direction of the flange portion, and a second convex portion disposed on the other side in the circumferential direction. The concave portion of the flange covering portion may have a first concave portion formed at a position overlapping the first convex portion in the radial direction, and a second concave portion formed at a position overlapping the second convex portion in the radial direction.

Advantages of the Invention

[0015] According to the present invention, in an electric motor in which a stator core and a coil are covered with a molding resin, it is possible to provide an electric motor that prevents the flange portion from falling inward and suppresses stress concentration around the resin-side recess.

Brief Description of the Drawings

[0016] [Figure 1] It is a cross-sectional view of an electric motor according to a first embodiment of the present invention. [Figure 2] It is a cross-sectional perspective view of a resin outer shell according to a first embodiment of the present invention. [Figure 3] It is a cross-sectional view of a resin outer shell according to a first embodiment of the present invention. [Figure 4] It is an exploded perspective view of a stator according to a first embodiment of the present invention. [Figure 5] It is a perspective view of a stator according to a first embodiment of the present invention. [Figure 6] It is a view showing an insulator and a resin outer shell according to a first embodiment of the present invention, (A) is a cross-sectional view seen from the axial direction, and (B) is a perspective view showing a convex portion of a flange portion and a concave portion of a flange covering portion. [Figure 7] It is a perspective view of a stator according to a second embodiment of the present invention. [Figure 8]A diagram showing an insulator and a resin outer shell according to a second embodiment of the present invention. (A) is a cross-sectional view taken from the axial direction, and (B) is a perspective view showing a convex portion of a flange portion and a concave portion of a flange covering portion. [Figure 9] A diagram showing an insulator and a resin outer shell according to a comparative example. (A) is a diagram showing a case where the dent on the outer side in the radial direction of the concave portion is large, and (B) is a diagram showing a case where the dent on the outer side in the radial direction of the concave portion is small.

Embodiments for Carrying Out the Invention

[0017] Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and may be different from the actual ones. Therefore, specific components should be determined with reference to the following description.

[0018] Also, the embodiments shown below are examples of devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention does not specify the shape, structure, arrangement, etc. of the components as follows. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.

[0019] <First Embodiment> Figure 1 is a cross-sectional view of the electric motor according to the first embodiment. Figure 2 is a cross-sectional perspective view of the resin outer casing 10 according to the first embodiment, and Figure 3 is a cross-sectional view of the resin outer casing 10 according to the first embodiment. Figure 4 is a perspective view of the stator 2 according to the first embodiment, and Figure 5 is a perspective view of the stator 2 according to the first embodiment. Furthermore, Figure 6 shows the insulator 22 and the resin outer casing 10 according to the first embodiment, where Figure 6(A) is a cross-sectional view seen from the axial direction (an enlarged view of the main part of Figure 3), and Figure 6(B) is a perspective view showing the convex portion 2210D of the flange portion 211D and the concave portion 101 of the flange covering portion 10a (an enlarged view of the main part of Figure 2). The electric motor 1 of the embodiment is used, for example, as a rotational drive source for a blower fan mounted on the indoor unit of an air conditioner.

[0020] [Overall configuration of the electric motor] The electric motor 1 comprises a stator 2, a rotor 3, a resin casing 10, a first bearing 61, a second bearing 71, and a cover member 4.

[0021] In the following description, as an example, we will explain an inner-rotor type brushless DC motor 1 in which a cylindrical rotor 3 having a permanent magnet section 31 (described later) is rotatably arranged radially inside a cylindrical stator 2 that generates a rotating magnetic field. Of course, the motor 1 is not limited to this, and may also be other motors such as an outer-rotor type brushless DC motor or an AC motor.

[0022] In the following explanation, the axis C of the rotating shaft 5 is also the central axis of the electric motor 1, that is, the axis of rotation of the rotor 3. The radial direction is the direction passing through the axis C and perpendicular to the axial direction. The inner diameter side is the inside in the radial direction, and the outer diameter side is the outside in the radial direction. Furthermore, the circumferential direction is the direction of rotation (circumferential direction) centered on the axis C. Also, below, the axial direction is the direction parallel to the axis C.

[0023] (Rotor) The rotor 3 has an annular permanent magnet portion 31 and a rotor body 30. The rotor body 30 has an outer circumferential surface and an inner circumferential surface. The permanent magnet portion 31 is fixed to the outer circumferential surface of the rotor body 30. The rotating shaft 5 is fixed to the inner circumferential surface of the rotor body 30. As a result, the rotating shaft 5 rotates together with the rotor body 30.

[0024] The rotor 3 is a surface magnet type in which a permanent magnet portion 31 is fixed in an annular shape to the outer circumferential surface. The permanent magnet portion 31 is formed in an annular shape by multiple (for example, 8 or 10) permanent magnets such that the north pole and south pole alternate at equal intervals in the circumferential direction. The permanent magnet portion 31 is typically formed from a metal sintered body such as an Nd-Fe-B alloy, but a plastic magnet formed in an annular shape by solidifying magnet powder with resin may also be used.

[0025] As shown in Figure 1, the rotor body 30 has an outer circumference core 32, an insulating member 33, and an inner circumference core 34.

[0026] The outer core 32 is formed in an annular shape and forms the outer surface of the rotor body 30. The outer core 32 is a laminate of plates made of multiple soft magnetic materials such as electromagnetic steel sheets. The inner core 34 is formed in an annular shape and forms the inner surface of the rotor body 30.

[0027] The inner circumferential core 34 is a laminate of plates made of multiple sheets of soft magnetic material such as electromagnetic steel. The rotating shaft 5 is fixed to the center of the inner circumferential core 34 by press-fitting or crimping.

[0028] The insulating member 33 electrically insulates the outer core 32 and the inner core 34. This reduces the difference between the capacitance on the stator side and the capacitance on the rotor side of the motor 1, thereby suppressing electrolytic corrosion of the bearings 61 and 71. The insulating member 33 is made of a dielectric resin such as PBT (polybutylene terephthalate) or PET (polyethylene terephthalate) and is fixed between the outer core 32 and the inner core 34. The insulating member 33 may be an annular molded body, or it may be a resin material filled between the outer core 32 and the inner core 34 by insert molding or the like.

[0029] (Stator) The stator 2 includes a stator core 21 having an annular yoke portion 211 and a plurality of teeth portions 212 projecting radially inward from the inner circumferential surface of the yoke portion 211, an insulator 22 positioned at the axial end of the stator core 21, and a plurality of coils 23 wound around the teeth portions 212 via the insulator 22 (see Figures 4 and 5). The stator core 21 is a laminate of plates made of a soft magnetic material such as a plurality of electromagnetic steel sheets. The plurality of coils 23 include three types of coils: U-phase, V-phase, and W-phase. These coils are interconnected, for example, via an electric neutral point (N point). The outer circumferential surface of this stator 2 (stator core 21) is covered with a resin outer shell 10 (see Figure 1). The stator 2 is arranged such that the permanent magnet portion 31 of the rotor 3 faces the stator core 21 of the stator 2 with a radial gap (magnetic gap) between them. The teeth portion 212 has a teeth surface 213 formed at the radially inner end of the teeth portion 212, which is a curved surface that is approximately circumferential. As described above, the teeth surface 213 faces the permanent magnet portion radially with an air gap (magnetic gap) between them.

[0030] The insulator 22 has a first insulator 221 attached to the stator core 21 from one axial direction of the annular yoke portion 211, and a second insulator 222 attached from the other axial direction (see Figures 1 and 4). The first insulator 221 and the second insulator 222 are each formed in an annular shape from an insulating synthetic resin. After the first insulator 221 is attached to the first end face 214 of the stator core 21 and the second insulator 222 is attached to the second end face 215 of the stator core 21, the coil 23 is wound around the teeth portion 212 via the first insulator 221 and the second insulator 222, and the resin outer shell 10 is formed by covering the first insulator 221, the second insulator 222 and the coil 23 with molded resin. In this embodiment, the first insulator 221 is formed from a single molded product without being divided in the circumferential direction. Similarly, the second insulator 222 is formed from a single molded product without being divided in the circumferential direction. Note that the first insulator 221 and the second insulator 222 may each be formed by connecting multiple molded products that are divided in the circumferential direction in an annular shape.

[0031] (Resin outer shell) The resin casing 10 is made of an insulating resin material. As shown in Figure 1, the resin casing 10 is formed in a hollow cylindrical shape with an open end 101 on one end in the axial direction (in this embodiment, the side opposite the output end 51 of the rotating shaft 5). Here, the opposite output end 51 is the end of the rotating shaft 5 opposite to the output end 52. The output end 52 is the load-side end (the side connected to the load) of the electric motor 1.

[0032] As described above, the resin outer shell 10 is integrally molded with the stator 2. The resin material constituting the resin outer shell 10 is not particularly limited and can be formed from, for example, BMC (Bulk Molding Compound: unsaturated polyester resin).

[0033] The resin casing 10 further has a second bearing housing 72 for housing a second bearing 71, which will be described later. The general shape of the second bearing housing 72 is a cylindrical shape with one end closed, centered on the axis C. The second bearing housing 72 is provided at the bottom 102 of the resin casing 10, opposite to the open end 101.

[0034] (Bearing) As shown in Figure 1, the first bearing 61 is a ball bearing having an outer ring 611, an inner ring 612, and multiple balls 613, etc. The second bearing 71 is a ball bearing having an outer ring 711, an inner ring 712, and balls 713, etc.

[0035] The outer ring 611 of the first bearing 61 is fixed to the cover member 4 (first bearing housing 41), and the inner ring 612 of the first bearing 61 is fixed to the side of the rotating shaft 5 opposite the output end 51. The outer ring 713 of the second bearing 71 is fixed to the resin casing 10 (second bearing housing 72), and the inner ring 712 of the second bearing 71 is fixed to the output end 52 of the rotating shaft 5. As a result, the rotating shaft 5 is supported by the first bearing 61 and the second bearing 71 so as to be rotatable around its axis C relative to the cover member 4 and the resin casing 10.

[0036] (Lid component) The lid member 4 has a first bearing housing portion 41 and a disc portion 42. The lid member 4 is attached to and fixed to the open end portion 101 of the resin outer shell 10. The lid member 4 is made of a metal material with excellent thermal conductivity, such as aluminum. The lid member 4 is molded, for example, by die casting.

[0037] The cover member 4 has two functions: it functions as a cover (bracket) that closes the opening of the resin outer casing 10 by covering the open end 101 of the resin outer casing 10, and it also functions as a bearing housing that supports the first bearing 61. The cover member 4 is fixed to the open end 101 of the resin outer casing 10 using a plurality of screw members (not shown).

[0038] The first bearing housing 41 houses the first bearing 61. The first bearing housing 41 has a generally cylindrical shape centered on the axis C and houses the first bearing 61.

[0039] (Details of the insulator) In the first embodiment, the first insulator 221 and the second insulator 222 have substantially the same basic components; therefore, only the first insulator 221 will be described below, and the description of the second insulator 222 will be omitted.

[0040] The first insulator 221 has an annular flange portion 221A, a wall portion 221B provided on the flange portion 221A and formed to follow the annular yoke portion 211, a winding drum portion 221C formed to follow the teeth portion 212, and a flange portion 221D that protrudes from the radially inner end of the winding drum portion 221C toward the opposite side of the stator core 21 in the axial direction.

[0041] The annular flange portion 221A abuts against the first end face 214 of the annular yoke portion 211 of the stator core 21 described above. This positions the first insulator 221 axially relative to the stator core 21.

[0042] The wall portion 221B is provided so as to protrude from the flange portion 221A in the axial direction away from the stator core 21. The wall portion 221B also supports the jumper wires of the coil 23.

[0043] The winding drum portion 221C is formed to extend radially inward from the flange portion 221A and covers the teeth portion 212, leaving the teeth surface 213 of the teeth portion 212 exposed. The winding drum portion 221C prevents the coil 23 from directly contacting the stator core 21 by winding the coil 23 around the teeth portion 212 of the stator core 21 via the winding drum portion 221C.

[0044] The flange portion 221D has a first projection 2221D that protrudes from the teeth portion 212 to one side in the circumferential direction when viewed from the axial direction, a second projection 2222D that protrudes from the teeth portion 212 to the other side in the circumferential direction when viewed from the axial direction, and a connecting portion 2220D that connects the first projection 2221D and the second projection 2222D.

[0045] The connecting portion 2220D is formed in a position that overlaps with the teeth portion 212 when viewed from the radial direction, and is formed so that a first projection 2221D is connected to one side in the circumferential direction and a second projection 2222D protruding to the other side in the circumferential direction.

[0046] The first projection 2221D is provided at one end of the connecting portion 2220D and is formed to protrude to one side in the circumferential direction from the teeth portion 212 when viewed from the radial direction. The first projection 2221D also has a first projection inclined portion 2221Da. The first projection inclined portion 2221Da is formed to be inclined such that the height of the first projection inclined portion 2221D in the axial direction decreases as it moves away from the circumferential center of the flange portion 221D.

[0047] The second projection 2222D is provided at the other end of the connecting portion 2220D and is formed to protrude radially from the teeth portion 212 on the other side in the circumferential direction. The second projection 2222D also has a second projection inclined portion 2222Da. The second projection inclined portion 2222Da is formed to be inclined such that the height of the second projection inclined portion 2222Da in the axial direction decreases as it moves away from the circumferential center of the flange portion 221D.

[0048] The flange portion 221D has a projection 2210D that protrudes radially inward. At least a portion of the projection 2210D of the flange portion 221D is formed on the connecting portion 2220D and protrudes radially inward more than the first projection 2221D and the second projection 2222D.

[0049] Furthermore, the convex portion 2210D of the flange portion 221D is formed to protrude in an approximately truncated square pyramidal shape (or rectangular parallelepiped shape) along the axial direction, and has an opposing convex portion 2212Da that faces the recess 101, which will be described later. The opposing convex portion 2212Da is a flat or curved surface formed along the circumferential direction.

[0050] (Details of the recess) The resin outer shell 10 has a flange covering portion 10a formed on the inner circumferential surface side that covers the radially inner surface of the flange portion 221D. As shown in Figure 2, the flange covering portion 10a is formed so as not to cover the tooth surface 213 of the tooth portion 212.

[0051] The flange covering portion 10a has a recess 101 that is recessed toward the flange portion 221D. As described above, the recess 101 is formed in a position that overlaps radially with the convex portion 2210D. Furthermore, the recess 101 is formed to be roughly truncated square pyramidal (or rectangular parallelepiped) when viewed radially, and has an opposing concave portion 101A that faces the opposing convex portion 2212Da. The opposing concave portion 101A is a curved surface or plane formed along the circumferential direction.

[0052] Furthermore, the recess 101 has inclined surfaces 1011A at both ends in the circumferential direction that are inclined to connect the inner circumferential surface of the flange covering portion 10a with the bottom of the recess 101. More specifically, multiple inclined surfaces 1011A are formed, one of which is inclined to connect the opposing recessed portion 101A with the inner circumferential surface of the flange covering portion 10a on the side of the first projection 2221D in the circumferential direction relative to the opposing recessed portion 101A. The other inclined surface is inclined to connect the opposing recessed portion 101A with the inner circumferential surface of the flange covering portion 10a on the side of the second projection 2222D in the circumferential direction relative to the opposing recessed portion 101A.

[0053] (Convex and concave parts) In terms of length along the axial direction (axial height), the axial height H1 (see Figure 5) of the opposing convex surface portion 2212Da of the convex portion 2210D is formed to be shorter than or approximately the same length as the axial height H2 of the opposing concave surface portion 101A of the concave portion 101.

[0054] Furthermore, in terms of length along the radial direction (radial height for the convex portion, radial depth for the concave portion), the radial height D1 of the opposing convex surface portion 2212Da of the convex portion 2210D is formed to be shallower than or equal to the radial depth D2 of the concave portion 101 (or the opposing concave surface portion 101A of the concave portion). Here, the direction along the axial height H2 and the direction along the radial depth D2 are orthogonal to each other.

[0055] Furthermore, in terms of length along the circumferential direction (circumferential width), the circumferential width W1 of the opposing convex portion 2212Da of the convex portion 2210D is formed to be shorter than the circumferential width W2 of the opposing concave portion 101A of the concave portion 101.

[0056] In the first embodiment, the distance K between the opposing convex surface 2212Da of the convex portion 2212D and the opposing concave surface 101A of the concave portion 101 is approximately 0.5 mm, but is not limited to this.

[0057] As described above, the flange portion 221D has a protrusion 2210D that projects radially inward, and the protrusion 2210D of the flange portion 221D is formed in a position that overlaps radially with the recess 101 of the flange covering portion 10a.

[0058] Figure 9 shows the insulator 22'' and resin outer shell 10'' according to the comparative example. In the first embodiment, a convex portion 2210D projecting radially inward was formed on the flange portion 221D, but the comparative example differs from the first embodiment in that no convex portion is formed on the flange portion 221D''. Figure 9(A) shows comparative example 1, in which the radial depth D2'', which is the size of the radial outward recess of the recess 101'', is larger (compared to comparative example 2), and Figure 9(B) shows comparative example 2, in which the radial depth D2''', which is the size of the radial outward recess of the recess 101'''', is smaller (compared to comparative example 1). The flange portion 221D'' of the insulator 22'' in both Comparative Example 1 and Comparative Example 2 has a first projection 2221D'' that protrudes from the teeth portion 212 to one side in the circumferential direction when viewed from the axial direction, a second projection 2222D'' that protrudes from the teeth portion 212 to the other side in the circumferential direction when viewed from the axial direction, and a connecting portion 2220D'' that connects the first projection 2221D'' and the second projection 2222D''. The resin outer casing 10'' of Comparative Example 1 has one recess 101'' that is recessed toward the flange portion 221D'' side. The recess 101'' is formed in a position where at least a part of it overlaps with the teeth portion 212 when viewed from the radial direction. The resin outer casing 10'' of Comparative Example 2 also has one recess 101'' that is recessed toward the flange portion 221D'' side. The recess 101''' is formed in a position where at least a portion overlaps with the tooth portion 212 when viewed from the radial direction. The radial depth D2'' of the recess 101'' in Comparative Example 1, which is recessed radially outward, is greater than the radial depth D2'''' of the recess 101'''' in Comparative Example 2, which is recessed radially outward. In other words, Comparative Example 1 corresponds to a case where the protrusion of the resin molding die is large, while Comparative Example 2 corresponds to a case where the protrusion of the resin molding die is small.

[0059] As in Comparative Example 1, when the radial depth D2'' of the recess 101'' that recesses radially outward is large (i.e., the amount of protrusion of the mold protrusion is large), a large recess is formed on the resin 10'' side at the corresponding position. This large change in the thickness of the resin 10'' around this recess may cause stress to concentrate around the recess that forms in the resin 10'' after resin molding. On the other hand, as in Comparative Example 2, when the radial depth D2''' of the recess 101'''' that recesses radially outward is small (i.e., the amount of protrusion of the mold protrusion is small), stress concentration around the recess can be suppressed. However, a force is applied to the flange 221D'' in a direction that causes it to tilt radially inward. During the resin molding process, until the resin hardens in the mold, the flange 221D'' may tilt inward until it hits the mold protrusion, which may reduce the effect of preventing the flange 221D'' from tilting inward.

[0060] In contrast, in the first embodiment, a convex portion 2210D is formed on the flange portion 221D, projecting radially inward, and the concave portion 101 of the resin outer casing 10 (flange covering portion 10a) and the convex portion 2210D of the flange portion 221D are arranged to overlap radially. As a result, even if the size of the recess 101 of the flange covering portion 10a is reduced, the distance between the concave portion 101 (opposing concave portion 101A) of the flange covering portion 10a and the convex portion 2210D (opposing convex portion 2212Da) of the flange portion 221D can be reduced. Therefore, even if the flange portion 221D tilts until it hits the protruding portion of the mold, the amount by which the flange portion 221D tilts can be reduced compared to Comparative Example 2, and the effect of preventing the flange portion 221D from tilting can be sufficiently ensured. Furthermore, since it becomes possible to reduce the size of the recess 101 formed in the flange covering portion 10a, it is possible to suppress stress concentration caused by a large recess 101.

[0061] Furthermore, the tooth surface 213 formed at the radially inner end of the tooth portion 212 is located radially inward from the convex portion 2210D. This prevents the distance between the stator core 21 and the coil 23 from decreasing, thereby ensuring insulation.

[0062] Furthermore, the protrusion 2210D is formed such that at least a portion of it overlaps with the teeth portion 212 when viewed from the radial direction. This makes it possible to improve the strength against stress applied to the radially inward side of the protrusion 2210D and prevents the flange portion 221D from tilting radially inward.

[0063] Furthermore, the first protruding inclined portion 2221Da is formed such that the height of the second protruding inclined portion 2222Da in the axial direction decreases as it moves away from the circumferential center of the flange portion 221D. This prevents the flange portion 221D of the insulator 22 of another adjacent tooth portion 212 from interfering with the winding of the coil 23 onto the tooth portion 212 when winding the wire onto the tooth portion 212 to be wound.

[0064] Furthermore, the recess 101 has first inclined surfaces 1011A at both ends in the circumferential direction, which are inclined to connect the inner circumferential surface of the flange covering portion 10a with the bottom of the recess 101 (opposing concave surface portion 101A). As a result, the deformation of the shape of the recess 101 is made gradual, and the concentration of stress on the recess 101 during mold molding can be suppressed.

[0065] The length (axial height) H1 of the convex portion 2210D (and its opposing convex surface portion 2212Da) is formed to be shorter than or equal to the length (axial height) H2 of the concave portion 101 (and its opposing concave surface portion 101A). As a result, the convex portion 2210D is supported from the inner circumferential side by the concave portion 101 over its entire axial height, effectively preventing the flange portion 221D from tilting toward the inner circumferential surface.

[0066] Furthermore, in terms of length along the radial direction (radial height for the convex portion, radial depth for the concave portion), the radial height D1 of the convex portion 2210D (and its opposing convex surface portion 2212Da) is formed to be shallower than or approximately the same as the radial depth D2 of the concave portion 101 (and its opposing concave surface portion 101A). This reduces the distance between the convex portion 2210D and the concave portion 101, simultaneously achieving the effect of suppressing the inclination of the flange portion 221D of the insulator 22 towards the inner circumference, and the effect of reducing the size (radial depth) of the concave portion 101 to suppress stress concentration.

[0067] Furthermore, the width W1 of the convex portion 2210D (and its opposing convex portion 2212Da) is formed to be longer than the width W2 of the concave portion 101 (and its opposing concave portion 101A) in terms of length along the circumferential direction (circumferential width). This makes it possible to slow down the shape change of the molded resin during molding, thereby suppressing molding defects.

[0068] <Second Embodiment> Figure 7 is a perspective view of the stator 2' according to a second embodiment of the present invention, and Figure 8 is a diagram showing the insulator 22' and resin outer shell 10 according to a second embodiment of the present invention, where (A) is a cross-sectional view taken from the axial direction, and (B) is a perspective view showing the flange portion 221D' and the recess 101 of the flange covering portion 10a.Hereafter, configurations different from the first embodiment will be mainly described, and the same reference numerals will be used for configurations similar to the first embodiment, and their descriptions will be omitted or simplified.

[0069] As shown in Figures 7, 8(A), and (B), the flange portion 221D' of this embodiment differs from the first embodiment in that the convex portion 2210D' projecting radially inward has two convex portions and two recesses corresponding to the two protrusions. Similar to the first embodiment described above, the insulator 22' of the stator 2' has a first insulator 221' and a second insulator 222'. The first insulator 221' will be described in the following description.

[0070] The first insulator 221' has an annular flange portion 221A, a wall portion 221B provided on the flange portion 221A and formed to follow the annular yoke portion 211, a winding drum portion 221C formed to follow the teeth portion 212, and a flange portion 221D' that protrudes from the radially inner end of the winding drum portion 221C toward the opposite side of the stator core 21 in the axial direction.

[0071] The flange portion 221D' has a first projection 2221D' that protrudes from the teeth portion 212 to one side in the circumferential direction when viewed from the axial direction, a second projection 2222D' that protrudes from the teeth portion 212 to the other side in the circumferential direction when viewed from the axial direction, and a connecting portion 2220D' that connects the first projection 2221D' and the second projection 2222D'.

[0072] The connecting portion 2220D' is formed in a position that overlaps with the teeth portion 212 when viewed from the radial direction, and is formed so that a first projection 2221D' is connected to one side in the circumferential direction and a second projection 2222D' is connected to the other side in the circumferential direction.

[0073] The first projection 2221D' is provided at one end of the connecting portion 2220D' and is formed to protrude to one side in the circumferential direction from the teeth portion 212 when viewed from the radial direction. The first projection 2221D' also has a first projection inclined portion 2221Da. The first projection inclined portion 2221Da is formed such that the height of the first projection inclined portion 2221Da in the axial direction decreases as it moves away from the circumferential center of the flange portion 221D'.

[0074] The second projection 2222D' is provided at the other end of the connecting portion 2220D' and is formed to protrude radially from the teeth portion 212 on the other side in the circumferential direction. The second projection 2222D' also has a second projection inclined portion 2222Da. The second projection inclined portion 2222Da is formed such that the height of the second projection inclined portion 2222Da in the axial direction decreases as it moves away from the circumferential center of the flange portion 221D'.

[0075] The flange portion 221D' has a protrusion 2210D' that projects radially inward. The protrusion 2210D' of the flange portion 221D' has a first protrusion 2211D located on at least a part of the first protrusion 2221D' and a second protrusion 2212D located on at least a part of the second protrusion 2222D'. In other words, the first protrusion 2221D is located on one side of the center of the teeth portion 212 in the width direction (circumferential direction), and the second protrusion 2222D is located on the other side of the center of the teeth portion 212 in the width direction (circumferential direction). Furthermore, the protrusion 2210D' (the first protrusion 2211D and the second protrusion 2212D) is located radially outward from the teeth surface 213 formed at the radially inward end of the teeth portion 212. In the second embodiment, the circumferential distance W' between the first protrusion 2211D and the second protrusion 2212D is approximately 1.5 mm, but is not limited to this.

[0076] In the second embodiment, the first protrusion 2211D is positioned to straddle the first projection 2221D' and the connecting portion 2220D' described above and is formed to protrude radially inward. That is, the first protrusion 2211D is formed so that at least a portion of it overlaps with the teeth portion 212 when viewed radially. The first protrusion 2211D is roughly truncated square pyramidal (or rectangular parallelepiped) in shape along the axial direction and has a first opposing convex surface portion 2211Da that faces the first recess 101a, which will be described later. The first opposing convex surface portion 2211Da is a plane or curved surface formed along the circumferential direction. The first protrusion 2211D also protrudes radially inward more than the first projection 2221D' and the second projection 2222D'.

[0077] In the second embodiment, the second protrusion 2212D is positioned to straddle the second projection 2222D' and the connecting portion 2220D' described above and is formed to project radially inward. That is, the second protrusion 2212D is formed so that at least a portion of it overlaps with the teeth portion 212 when viewed radially. The second protrusion 2212D is roughly frustoconical (or rectangular parallelepiped) in shape formed along the axial direction and has a second opposing convex surface portion 2212Da that faces the second recess 102a, which will be described later. The second opposing convex surface portion 2212Da is a plane or curved surface formed along the circumferential direction. The second protrusion 2212D also projects radially inward more than the first projection 2221D' and the second projection 2222D'.

[0078] (Details of the recess) The resin outer shell 10 has a flange covering portion 10a formed on the inner circumferential surface side that covers the radially inner surface of the flange portion 221D. As shown in Figures 8(A) and 8(B), the flange covering portion 10a' is formed so as not to cover the tooth surface 213 of the tooth portion 212.

[0079] The flange covering portion 10a' has a recess 101' that is recessed toward the flange portion 221D'. The recess 101' of the flange covering portion 10a' has a first recess 101a formed at a position that radially overlaps with at least a portion of the first projection 2211D', and a second recess 102a formed at a position that radially overlaps with at least a portion of the second projection 2212D. In the second embodiment, the circumferential distance W'' between the first recess 101a and the second recess 102a is approximately 1.5 mm, but is not limited to this.

[0080] In the second embodiment, the first recess 101a is positioned to overlap with the first projection 2221D' and the connecting portion 2220D' described above in the radial direction and is formed to protrude radially outward. The first recess 101a is also formed to overlap with the first convex portion 2211D' in the radial direction. Furthermore, the first recess 101a is formed to be approximately truncated square pyramidal (or rectangular parallelepiped) when viewed from the radial direction and has a first opposing concave portion 1011a that faces the first opposing convex portion 2211Da. The first opposing concave portion 1011a is a surface parallel to the circumferential direction.

[0081] In the second embodiment, the second recess 102a is positioned in a location that overlaps with the second projection 2222D' and the connecting portion 2220D' in the radial direction and is formed to protrude radially inward. The second recess 102a is also formed in a location that overlaps with the second convex portion 2212D' in the radial direction. Furthermore, the second recess 102a is formed to be approximately truncated square pyramidal (or rectangular parallelepiped) in shape when viewed from the radial direction, and has a second opposing concave portion 1021a that faces the second opposing convex portion 2212Da. The second opposing concave portion 1021a is a surface parallel to the plane perpendicular to the radial direction.

[0082] (Convex and concave parts) In terms of length along the axial direction (axial height), the axial height H1' (see Figure 7) of the first opposing convex surface 2211Da of the first convex portion 2211D is formed to be shorter than or approximately the same length as the axial height H2' of the first recess 101a (the first opposing concave surface 1011a). Similarly, in terms of length along the axial direction, the axial height of the second opposing convex surface 2212Da of the second convex portion 2212D is formed to be shorter than or approximately the same length as the axial height of the second opposing concave surface 1021a of the second recess 102a.

[0083] Furthermore, in terms of length along the radial direction (radial height for the convex portion, radial depth for the concave portion), the radial height D1' of the first opposing convex surface portion 2211Da of the first convex portion 2211D is formed to be shallower than or equal to the radial depth D2' of the first opposing concave surface portion 1011a of the first concave portion 101a. Similarly, in terms of length along the radial direction, the radial height of the second opposing convex surface portion 2212Da of the second convex portion 2212D is formed to be shallower than or equal to the radial depth of the second opposing concave surface portion 1021a of the second concave portion 102a.

[0084] Furthermore, the circumferential width W1' of the first opposing convex portion 2211Da of the first convex portion 2211D is formed to be longer than the circumferential width W2' of the first opposing concave portion 1011a of the first concave portion 101a. Similarly, the circumferential width of the second opposing convex portion 2212Da of the second convex portion 2222D is formed to be longer than the circumferential width of the second opposing concave portion 1021a of the second concave portion 102a.

[0085] In the second embodiment, the distance K' between the first opposing convex portion 2211Da of the first convex portion 2211D and the first opposing concave portion 1011a of the first concave portion 101a is approximately 0.5 mm, but is not limited to this.

[0086] In the above configuration, the first recess 101a is formed at a position that radially overlaps with the first protrusion 2211D, and the second recess 102a is formed at a position that radially overlaps with the second protrusion 2212D. This makes it possible to reduce the distance between the bottom surface of the recess 101' of the flange covering portion 10a' and the flange portion 221D', even if the size of the recess 101' of the flange covering portion 10a' is reduced (and the size of the protrusion 2210D' is also reduced). Even if the flange portion 221D' tilts until it hits the protrusion of the mold, the amount by which the flange portion 221D' tilts can be reduced compared to Comparative Example 2, and radial inward tilting of the flange portion 221D' can be prevented. Furthermore, since it is possible to reduce the size of the recess 101' formed in the flange covering portion 10a', stress concentration due to a large recess 101' can be suppressed.

[0087] Furthermore, the tooth surface 213 formed at the radially inner end of the tooth portion 212 is located radially inward from the protrusion 2210D' (the first protrusion 2211D and the second protrusion 2212D). This prevents the distance between the stator core 21 and the coil 23 from decreasing, thereby ensuring insulation.

[0088] Furthermore, the protrusion 2210D' is formed such that at least a portion of it overlaps with the teeth portion 212 when viewed from the radial direction. This makes it possible to improve the strength against stress applied to the radially inward side of the protrusion 2210D' and prevents the flange portion 221D' from tilting inward in the radial direction.

[0089] The length (axial height) H1' of the first convex portion 2211D (the first opposing convex portion 2211Da) is formed to be shorter than or approximately the same as the length (axial height) H2' of the first concave portion 101a (the first opposing concave portion 1011a). Similarly, the length (axial height) of the second convex portion 2212D (the second opposing convex portion 2212Da) is formed to be shorter than or approximately the same as the length (axial height) of the second concave portion 102a (the second opposing concave portion 1021a). As a result, the protrusions 2210D (first protrusion 2211D, second protrusion 2212D) are supported from the inner circumference by the recesses 101 (first recess 101a, second recess 101b) over the entire axial height, so that the flange portion 221D' does not tilt inward.

[0090] Furthermore, in terms of length along the radial direction (radial height for the convex portion, radial depth for the concave portion), the radial height D1' of the first convex portion 2211D (the first opposing convex portion 2211Da) is formed to be shallower than or equal to the radial depth D2' of the first concave portion 101a (the first opposing concave portion 1011a). Similarly, in terms of length along the radial direction, the radial height of the second convex portion 2212D (the second opposing convex portion 2212Da) is formed to be shallower than or equal to the radial depth of the second concave portion 102a (the second opposing concave portion 1021a). This makes it possible to reduce the distance between the first protrusion 2211D and the first recess 101a, and the distance between the second protrusion 2212D and the second recess 101b, thereby simultaneously achieving the effect of suppressing the inclination of the flange portion 221D' of the insulator 22 towards the inner circumference, and the effect of reducing the size (radial depth) of the recesses 101' (first recess 101a, second recess 101b) and suppressing stress concentration.

[0091] Furthermore, the circumferential width W1' of the first convex portion 2211D (the first opposing convex portion 2211Da) is formed to be longer than the circumferential width W2' of the first concave portion 101a (the first opposing concave portion 1011a) in terms of length along the circumferential direction. Similarly, the circumferential width of the second convex portion 2222D (the second opposing convex portion 2212Da) is formed to be longer than the circumferential width of the second concave portion 102a (the second opposing concave portion 1021a) in terms of length along the circumferential direction. This makes it possible to slow down the shape change of the molded resin during mold molding, thereby suppressing molding defects.

[0092] Furthermore, in the first embodiment, the number of protrusions 2210D (protrusions 2210D') and recesses 101 (recesses 101') was two, but of course, it is not limited to this, and there may be three or more. [Explanation of Symbols]

[0093] 1...Electric motor 2…Status 3…Rotor 4...Lid part 5…Rotation axis 10… Resin outer shell 10a...Flange covering 21… Stator core 22... Insulator 23... Coil 101…recess 101a...First recess 102a...Second recess 211... York 212... Teeth Department 221A...Flange section 221B…Wall part 221C…Reeling trunk 221D…Tsubabe 2210D… protruding part 2211D...First protrusion 2212D...Second convex part 2221D...First protrusion 2222D...Second protrusion C…Axis center

Claims

1. The stator core comprises an annular yoke portion and a plurality of teeth portions projecting radially inward from the inner circumferential surface of the yoke portion; an insulator disposed at the axial end of the stator core; a coil wound around the teeth portion via the insulator; a resin outer shell formed to cover the stator core and the coil; and a rotor disposed radially inward of the stator core. The insulator has a winding drum portion formed along the teeth portion, and a flange portion that protrudes from the radially inner end of the winding drum portion toward the opposite side of the axial direction from the stator core, The resin outer shell has a flange covering portion that covers the radially inner surface of the flange portion, The flange covering portion has a recess that is recessed toward the flange portion side, The flange portion has a convex portion that protrudes radially inward, The protrusion of the flange portion is formed in a position that overlaps with the recess of the flange covering portion in the radial direction. Electric motor.

2. The electric motor according to claim 1, The radially inner end of the teeth portion is located radially inward from the convex portion of the flange portion. Electric motor.

3. The electric motor according to claim 1, The recess of the flange covering portion has inclined surfaces at both ends in the circumferential direction that connect the inner circumferential surface of the flange covering portion with the bottom of the recess. Electric motor.

4. The electric motor according to claim 1, The convex portion of the flange has a first convex portion located on one side in the circumferential direction with respect to the center of the flange in the circumferential direction, and a second convex portion located on the other side in the circumferential direction. The recess of the flange covering portion has a first recess formed at a position overlapping the first protrusion in the radial direction, and a second recess formed at a position overlapping the second protrusion in the radial direction. Electric motor.

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