Motor

Abstract

The invention improves the rigidity of a rotor in a motor during rotation. This motor (200) is provided with: a shaft (101); a stator (130); a bearing (111) disposed between the shaft (101) and the stator (130); and a rotor (120) that rotates integrally with the shaft (101), the rotor (120) having a magnet (122) and a cover (129) that is fixed to the shaft (101) and covers the magnet (122), the cover (129) having: a protrusion (125) that protrudes toward the bearing (111) in the axial direction; and an arm portion (126) protruding from the protruding portion (125) toward the bearing (111) in the axial direction.

Description

Technical Field

[0001] The present invention relates to a motor. Background Art

[0002] Conventionally, in an outer rotor type motor having a stator and a rotor, the stator has a bearing holding portion, and ball bearings are provided at the upper and lower portions of the bearing holding portion. The shaft of the rotor is mounted on the cover portion of the yoke of the cup portion, and is rotatably supported by the upper and lower ball bearings (for example, see Patent Document 1). Prior art literature Patent Literature

[0003] Patent Document 1: Japanese Patent Application Publication No. 2008-175158 Summary of the invention Problems to be solved by the invention

[0004] In an outer rotor type motor of such a structure, since a cover serving as a weight is fixed to one side (upper portion) of the shaft, when the cover rotates with the shaft, the load on the shaft and the upper ball bearing increases, causing concern that the shaft rigidity may be insufficient when the rotor rotates. One example of the subject of the present invention is to improve the shaft rigidity when the rotor in the motor rotates. Solutions for solving problems

[0005] The motor of the present invention comprises: a shaft; a stator; a bearing arranged between the shaft and the stator; and a rotor rotating integrally with the shaft, the rotor having a magnet and a cover, the cover being fixed to the shaft and covering the magnet, the cover having: a protrusion protruding axially toward the bearing; and an arm protruding axially from the protrusion toward the bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is a perspective view of a fan having a motor as an example embodiment of the present invention. Figure 2 This is a cross-sectional view of a fan including a motor according to an example embodiment of the present invention. Figure 3 is a cross-sectional view of a fan having a motor as an example embodiment of the present invention, Figure 2 AA section view in. Figure 4 This is a partially enlarged cross-sectional view of a fan including a motor according to an example embodiment of the present invention. DETAILED DESCRIPTION

[0007] Hereinafter, an embodiment as an example of the present invention will be described with reference to the drawings. Figure 1It is a perspective view of the fan 200 according to the present embodiment. Figure 2 is a cross-sectional view of the fan 200, Figure 3 It's a fan Figure 2 AA section view in the figure, Figure 4 It is a partially enlarged cross-sectional view of the fan 200 .

[0008] It should be noted that in the description of the embodiments of the present invention, for the sake of convenience, the arrow a direction along the axis X is set as the upper side or one side of the axial direction. The arrow b direction along the axis X is set as the lower side or the other side of the axial direction. Here, the arrow ab directions are referred to as the up-down direction or the axial direction. However, the up-down direction is not necessarily consistent with the vertical direction. In addition, the arrow cd direction is referred to as the radial direction, the arrow c direction away from the axis X is referred to as the outer side or one side of the radial direction, and the arrow d direction close to the axis X is referred to as the inner side or the other side of the radial direction.

[0009] like Figure 1 As shown in FIG. 1 , the fan 200 of the present embodiment is a blower that delivers air from the upper side of one axial side (the direction of arrow a) toward the lower side of the other axial side (the direction of arrow b). The fan 200 has a motor 100 ( Figure 2 ) and an impeller 210 arranged on one axial side of the shaft 101 of the motor 100.

[0010] The impeller 210 is formed of a hub 211 and a plurality of blades 212, and is driven to rotate by the motor 100. Figure 1 As shown, the fan 200 is formed in a substantially square cylindrical shape in a plan view, and has an air intake port 201 for sucking air from one axial side into a wind tunnel portion in a hollow cylindrical shape.

[0011] The fan 200 has four flanges 202 at one axial corner and four flanges 203 at the other axial corner. The four flanges 202 at one axial corner and the four flanges 203 at the other axial corner are provided with through holes for inserting bolts (not shown) for mounting on a predetermined device or housing.

[0012] like Figure 2 and Figure 3 As shown in FIG. 1 , the fan 200 comprises: a side wall 204 which is rectangular in plan view and surrounds the impeller 210 from one radial side (arrow c direction); a motor base 205 which is formed at the end of the other axial side; and a plurality of fixed blades 206 which are composed of a plurality of stationary blades connecting the side wall 204 and the motor base 205 in the radial direction (arrow cd direction). It should be noted that a plurality of spokes composed of rod-shaped parts may be used instead of the fixed blades 206 connecting the side wall 204 and the motor base 205.

[0013] The side wall 204, motor base 205 and fixed blade 206 of the fan 200 are integrally formed by injection molding of synthetic resin such as polybutylene terephthalate reinforced with glass fiber, for example. The side wall 204, motor base 205 and fixed blade 206 may be formed of other materials.

[0014] The side wall 204 forms a wind tunnel portion of the fan 200. The wind tunnel portion of the side wall 204 has an inner peripheral surface 204a of a cylindrical shape centered on the axis X. The diameter of the inner peripheral surface 204a is such that it does not contact the radial end of the blade 212 of the impeller 210. That is, a predetermined gap exists between the radial end of the blade 212 of the impeller 210 and the inner peripheral surface 204a of the side wall 204.

[0015] The side wall 204 also functions as a protection part for protecting the impeller 210. Four flanges 202 are integrally formed with the side wall 204 at one axial corner. Four flanges 203 are also integrally formed with the side wall 204 at the other axial corner.

[0016] The motor base portion 205 is formed by a base portion 205a that is roughly disc-shaped, a cylindrical outer wall 205b that extends a specified length from the end on one radial side of the base portion 205a to the one axial side, and a cylindrical boss portion 205c that protrudes a specified length from the end on the other radial side (in the direction of arrow d) of the base portion 205a to the one axial side.

[0017] A fixed blade 206 is integrally formed on one radial surface of an outer peripheral wall 205 b of the motor base 205 . The outer peripheral wall 205 b of the motor base 205 is supported by the side wall 204 of the fan 200 via the fixed blade 206 .

[0018] The impeller 210 includes a hub 211 having a bottomed cup-like shape with a substantially inverted U-shaped cross section, and a plurality of blades 212 provided on the outer peripheral surface (radial side surface) of the hub 211 along the circumferential direction.

[0019] The plurality of blades 212 all have the same shape and are evenly spaced in the circumferential direction of the hub 211. The hub 211 and the plurality of blades 212 are integrally formed by injection molding of a synthetic resin such as polybutylene terephthalate reinforced with glass fiber, for example.

[0020] The hub 211 of the impeller 210 is fixed to the outer peripheral surface (surface on one radial side) of the cylindrical portion 121 of the rotor 120 described later and the surface on one axial side of the cover portion 123 of the rotor 120. It should be noted that the cylindrical portion 121 of the rotor 120 may be embedded in the hub 211 so that the inner peripheral surface (surface on the other radial side) of the hub 211 and the outer peripheral surface (surface on one radial side) of the cylindrical portion 121 of the rotor 120 may be formed integrally.

[0021] The motor 100 includes a shaft 101 and a bearing device 110. The bearing device 110 includes a bearing 111a provided on one side in the axial direction, a bearing 111b provided on the other side in the axial direction, and a holding member 112 for holding the bearings 111a and 111b.

[0022] The retaining member 112 is formed of metal and has a hollow cylindrical shape as a whole. The retaining member 112 is pressed into the inner peripheral surface (the surface on the other radial side) of the boss portion 205c of the motor base portion 205. It should be noted that the retaining member 112 can also be set to be embedded in the boss portion 205c and formed integrally with the motor base portion 205.

[0023] The holding member 112 holds the bearing 111a on one axial side and the bearing 111b on the other axial side. The bearings 111a and 111b are ball bearings. It should be noted that the bearings 111a and 111b are not limited to ball bearings, and may be other bearings such as sleeve bearings. In addition, a spring for preloading may be provided between the bearings 111a and 111b.

[0024] The outer ring 111ao of the bearing 111a and the outer ring 111bo of the bearing 111b are bonded or press-fitted to the inner peripheral surface (the surface on the other radial side) of the holding member 112. That is, the outer ring 111ao of the bearing 111a and the outer ring 111bo of the bearing 111b are fixed integrally with the holding member 112.

[0025] The inner ring 111ai of the bearing 111a and the inner ring 111bi of the bearing 111b are bonded or press-fitted to the outer peripheral surface of the cylindrical shaft 101. That is, the inner ring 111ai of the bearing 111a and the inner ring 111bi of the bearing 111b are fixed integrally with the shaft 101.

[0026] The bearing 111a supports one axial side of the shaft 101 so as to be rotatable relative to the holding member 112, and the bearing 111b supports the other axial side of the shaft 101 so as to be rotatable relative to the holding member 112. Thus, the shaft 101 is supported by the bearings 111a and 111b so as to be rotatable relative to the holding member 112.

[0027] Motor 100 is an outer rotor type single-phase brushless DC motor having a rotor 120 and a stator 130. Motor 100 is not limited to a single-phase brushless DC motor, and may be a motor of various structures such as a three-phase brushless DC motor.

[0028] The rotor 120 is fixed only to one axial side of the shaft 101. The shaft 101 is press-fitted to the inner peripheral surface of the protrusion 125 and bonded and fixed.

[0029] The rotor 120 has a cover 129. The cover 129 has a cylindrical portion 121, which is coaxially arranged with the shaft 101 and is made of a soft magnetic material; a disc-shaped cover portion 123, which extends from an end portion of one axial side of the cylindrical portion 121 toward the other radial side; and a protrusion 125, which protrudes from the central portion of the cover portion 123 in the axial direction toward the bearing 111a.

[0030] A cylindrical magnet 122 is fixed to the inner peripheral surface of the cylindrical portion 121 coaxially and integrally with the cylindrical portion 121. The cylindrical portion 121 functions as a portion for preventing the magnetic field of the magnet 122 from leaking.

[0031] One axial end of magnet 122 does not contact cover 123, and magnet 122 is separated from cover 123 by a predetermined distance. The other axial end of magnet 122 slightly protrudes downward from the other axial end of cylinder 121.

[0032] Thus, magnet 122 is arranged to protrude downward from cylinder 121. This is because when magnet 122 is arranged as far as possible on the other axial side, that is, on the lower side, relative to cylinder 121, the center of gravity of cover 129 is on the lower side, which can reduce the axial load on shaft 101 during rotation on one axial side.

[0033] The cylindrical portion 121 and the cover portion 123 of the cover 129 are covered by the hub 211 of the impeller 210 and fixed integrally by adhesive or the like. The cover portion 123 is a portion having a function as a cover formed integrally with the cylindrical portion 121 to prevent the entry of foreign matter. It should be noted that the protrusion 125 will be described later.

[0034] The stator 130 is attached to the outer peripheral surface of the holding member 112. However, the stator 130 may be directly attached to the motor base 205 without interposing the holding member 112 therebetween.

[0035] The stator 130 includes a stator core 131 formed by laminating a plurality of electromagnetic steel sheets made of soft magnetic material, an insulator 132 attached to the stator core 131 and made of an insulating material, and a coil 133 wound around the stator core 131 via the insulator 132. The stator core 131 and the coil 133 are insulated by the insulator 132.

[0036] like Figure 3 As shown, the stator core 131 comprises: an annular portion 131a, centered on the axis X; a plurality of (four in this case) teeth 131b, extending from the annular portion 131a toward one radial side (direction of arrow c); and a magnetic pole portion 131c, formed at the end of the outer peripheral side of each tooth portion 131b. Figure 3 The coil 133 is omitted.

[0037] The inner circumference of the annular portion 131a of the stator core 131 is fixed to the outer circumference of the holding member 112. The magnetic poles 131c of the stator core 131 protrude circumferentially to both sides, and the distance between adjacent magnetic poles 131c is set shorter than the distance between adjacent teeth 131b.

[0038] When the motor 100 is operated and the rotor 120 rotates together with the shaft 101 by electromagnetic action between the rotor 120 and the stator 130, the impeller 210 fixed to the rotor 120 rotates and sends air toward the other side of the axial direction by the action of the plurality of blades 212. Therefore, the fan 200 functions as a blower.

[0039] like Figure 2 and Figure 4 As shown, in this structure, the protrusion 125 formed on the cover 123 of the cover 129 of the motor 100 is a convex portion that protrudes from the cover 123 toward the bearing 111 a on the other side in the axial direction by a predetermined length.

[0040] The protrusion 125 includes: a cylindrical portion (hereinafter referred to as the "axial extension portion") 125a, which extends a specified length toward the other axial side; and a disc portion (hereinafter referred to as the "radial extension portion") 125b, which extends a specified length from the end of the other axial side of the axial extension portion 125a toward the other radial side.

[0041] The axially extending portion 125a is a cylindrical portion extending a predetermined length toward the other axial side from the center of the cover portion 123, and its other axial end is integrally formed with the radially extending portion 125b. The axially extending portion 125a has a length that does not reach the retaining member 112 in the axial direction.

[0042] The radially extending portion 125b is a disc-shaped portion extending a predetermined length from the end of the axially extending portion 125a toward the shaft 101, and has a through hole 125bh formed in the center for inserting the shaft 101. The radially extending portion 125b has a length (radius) in the radial direction from the end of the axially other side of the axially extending portion 125a to the shaft 101.

[0043] The inner diameter of the through hole 125bh in the radially extending portion 125b is the same as or slightly smaller than the outer diameter of the shaft 101. The shaft 101 is press-fitted into the through hole 125bh of the radially extending portion 125b and fixed integrally therewith by an adhesive.

[0044] It should be noted that the axial thickness t1 of the radially extending portion 125b is thicker than the axial thickness t2 of the axially extending portion 125a. This is because, since the end of the shaft 101 on one axial side is supported only by the radially extending portion 125b of the protrusion 125, it is necessary to increase the rigidity of the radially extending portion 125b supporting the shaft 101. Thus, the shaft rigidity can be increased when the cover 129 rotates integrally with the shaft 101.

[0045] The protruding portion 125 has a cylindrical concave space S surrounded by the axially extending portion 125a and the radially extending portion 125b. The axial end of the shaft 101 protruding from the through hole 125bh of the radially extending portion 125b is exposed in the concave space S.

[0046] The end of the shaft 101 protrudes axially from the upper end surface 125ba of the radially extending portion 125b of the protrusion 125, but does not protrude axially more than the upper end surface 123a of the cover portion 123. However, the end of the shaft 101 on one side in the axial direction only needs to not contact the hub 211, and may be flush with the upper end surface 123a of the cover portion 123 or protrude slightly more than the upper end surface 123a.

[0047] In the protrusion 125, although the axial end of the shaft 101 protrudes from the upper end surface 125ba of the radially extending portion 125b, the through hole 125bh and the outer peripheral surface of the shaft 101 are fixed without a gap, which prevents the intrusion of foreign matter from the outside.

[0048] The radially extending portion 125b is integrally formed with a cylindrical arm portion 126, and the arm portion 126 extends from the end portion on the other radial side of the radially extending portion 125b toward the other axial side by a length that does not reach the bearing 111a. That is, there is a small gap in the axial direction between the end portion on the other axial side of the arm portion 126 and the bearing 111a, and a washer 128 is installed in the gap.

[0049] like Figure 4 As shown in FIG. 1 , a tapered surface 126t is formed on the inner circumferential surface of the opening portion at the end portion on the other axial side of the arm portion 126. Specifically, a conical tapered surface 126t is formed on the inner circumferential surface of the arm portion 126 that contacts the shaft 101, and the tapered surface 126t is inclined so as to gradually move away from the outer circumferential surface of the shaft 101 from the inner circumferential surface toward the top end of the opening of the arm portion 126. That is, the arm portion 126, which is a portion protruding from the protrusion 125, has an inclined inner circumferential surface (tapered surface 126t), and in the radial direction, the inner diameter of the inclined inner circumferential surface on the bearing side of the arm portion 126 is larger than the inner diameter of the inclined inner circumferential surface on the end side (one axial side) of the arm portion 126 on the shaft 101.

[0050] Thus, the other axial end of the arm portion 126 is separated from the outer peripheral surface of the shaft 101 by the tapered surface 126t. Thus, the shaft 101 can be easily inserted from the arm portion 126 of the cover 129 into the through hole 125bh of the radially extending portion 125b.

[0051] A washer 128 is interposed between the other axial end of the arm 126 and the bearing 111a, and the arm 126 and the bearing 111a are in contact with each other via the washer 128. It should be noted that the arm 126 may directly contact the bearing 111a without the washer 128 interposed therebetween.

[0052] In this manner, the arm portion 126 of the protruding portion 125 directly or indirectly contacts the bearing 111 a , and thus the bearing 111 a held by the holding member 112 can be restricted from moving to one side in the axial direction.

[0053] In addition, if Figure 2 As shown, from the end portion of the cover 129 on one side in the axial direction, that is, the upper end surface 123a ( Figure 4 ) to the end portion on the other axial side of the magnet 122 is set to be longer than 1 / 2 of the length D2 from the end portion on one axial side to the end portion on the other axial side of the holding member 112. That is, the relationship D1>D2 / 2 is satisfied.

[0054] Thus, satisfying the relationship D1>D2 / 2 means that magnet 122 is installed on cylindrical portion 121 of cover 129 in a manner protruding downward. By setting it in this way, the center of gravity of cover 129 is on the lower side, which can reduce the shaft load when rotating on one side of shaft 101 in the axial direction and improve shaft rigidity.

[0055] According to the above configuration, fan 200 includes protrusion 125 provided on cover 123 of cover 129 , and shaft 101 is supported by radially extending portion 125 b provided at a position of protrusion 125 close to bearing 111 a .

[0056] Therefore, the shaft 101 is supported by the bearings 111a and 111b, and is also supported near the bearing 111a by the radially extending portion 125b of the protrusion 125 of the cover 129 integrated with the impeller 210 as a weight. Thus, the shaft rigidity when the impeller 210 rotates can be improved compared to the past, so that the rotation of the impeller 210 can be stabilized.

[0057] In addition, the end portion of the shaft 101 on one axial side is exposed to the concave space S from the through hole 125bh of the radially extending portion 125b in the cover 129, and is supported by the radially extending portion 125b at a portion lower than the end portion of the shaft 101 on one axial side. Therefore, compared with the case where the end portion of the shaft 101 on one axial side is supported by the radially extending portion 125b, the shaft rigidity when the shaft 101 and the cover 129 rotate as a whole is improved, and the sense of stability is increased.

[0058] The cover 129 forms a concave space S by the axially extending portion 125a and the radially extending portion 125b of the protrusion 125, thereby making it possible to reduce the weight of the cover 129 compared to a case where the concave space S is not formed, thereby further improving the shaft rigidity when the shaft 101 and the cover 129 rotate as a whole.

[0059] The motor of the present invention has been described above by taking a preferred embodiment as an example, but the motor of the present invention is not limited to the structure of the above embodiment. For example, in the above embodiment, the motor 100 is used for the fan 200, but the motor of the present invention can also be used for drones and other various devices.

[0060] In the above embodiment, the case where the motor 100 is an outer rotor type motor is described, but the present invention is not limited thereto, and the motor 100 may be an inner rotor type motor.

[0061] In the above embodiment, the motor 100 is described as having two bearings. However, the present invention is not limited thereto, and the motor 100 may have three or more bearings depending on the length of the shaft 101 .

[0062] In the above embodiment, the motor 100 is described as being configured to form a tapered surface 126t on the inner peripheral surface of the opening portion at the end portion on the other axial side of the arm portion 126, but the present invention is not limited to this, and it can also be configured to bend the end portion on the other axial side of the arm portion 126 in a manner away from the outer peripheral surface of the shaft 101.

[0063] Furthermore, those skilled in the art can appropriately modify the motor of the present invention according to conventional knowledge, and can also change the combination of various structures. As long as the structure of the present invention is still provided through such modification, it is naturally included in the scope of the present invention. Description of Reference Numerals

[0064] 100: motor; 101: shaft; 110: bearing device; 111a, 111b: bearing; 111ai, 111bi: inner ring; 111ao, 111bo: outer ring; 112: holding member; 120: rotor; 121: cylindrical portion; 122: magnet; 123: cover portion; 125: protrusion; 128: washer; 129: cover; 130: stator; 131: stator core; 131a: annular portion; 13 1b: tooth portion; 131c: magnetic pole portion; 132: insulator; 133: coil; 200: fan; 201: air inlet; 202: flange portion; 203: flange portion; 204: side wall; 204a: inner peripheral surface; 205: motor base portion; 205a: base portion; 205b: outer peripheral wall; 205c: boss portion; 206: fixed blade; 210: impeller; 211: hub; 212: blade; S: concave space.

Claims

1. A motor, comprising: axis; stator; a bearing disposed between the shaft and the stator; and a rotor, rotating integrally with the shaft, The rotor has a magnet and a cover, the cover is fixed to the shaft and covers the magnet, The cover has: a protrusion protruding toward the bearing in the axial direction; and The arm portion protrudes from the protruding portion toward the bearing in the axial direction.

2. The motor according to claim 1, wherein: An end portion of the shaft is exposed from the protrusion.

3. The motor according to claim 1 or 2, wherein: The protrusion has an axially extending portion extending in the axial direction and a radially extending portion extending in the radial direction, The thickness of the radially extending portion in the axial direction is thicker than the thickness of the axially extending portion in the axial direction.

4. The motor according to claim 1, wherein: The portion protruding from the protrusion has an inclined inner peripheral surface, In the radial direction, the inner diameter of the inclined inner peripheral surface on the bearing side is larger than the inner diameter of the inclined inner peripheral surface at the end side of the shaft.

5. The motor according to claim 1, wherein: The motor has a holding member that holds the shaft. A length from an end portion on one axial side of the cover to an end portion on the other axial side of the magnet is longer than half of a length of the holding member in the axial direction.

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