JP2014015853A - Centrifugal fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cool a circuit board by adopting an outer rotor type motor structure and utilizing an air flow generated by an impeller.SOLUTION: A centrifugal fan 1A has a motor holder 51A fixed to a mounting plate 25A. The motor holder has plural columns 511A, a plate-like section 512A, an exhaust port 514A, and a window section 515A. The plural columns extend in an axial direction outside a rotor holder 32A and a circuit board 24A in a radial direction. The plate-like section is enlarged outward in the radial direction from upper ends of the columns. The exhaust port is positioned below an impeller, and penetrates through at least one portion of the plate-like section in the axial direction. The window section penetrates in the radial direction above the mounting plate and between the adjacent columns. Gas accelerated by rotating the impeller flows downward through the exhaust port. Also, one portion of the gas passes through the window section of the motor holder, and collides with the circuit board.

Description

  The present invention relates to a centrifugal fan.

Conventionally, a blower such as a centrifugal fan that is mounted on a vacuum cleaner or a handy cleaner and generates a suction force is known. A conventional blower is described in, for example, Japanese Patent Application Laid-Open No. 2011-115253. The electric blower of the publication has an electric motor and a centrifugal impeller fixed to the shaft of the electric motor (paragraph 0010). When electric power is supplied to the electric motor of this publication, the shaft rotates, so that the centrifugal impeller attached to the shaft rotates and sucks air from the suction port (paragraph 0015). Further, the air discharged from the centrifugal impeller is guided to the electric motor side to cool the electric motor (paragraph 0016).
JP 2011-115253 A

  According to FIG. 2 of Unexamined-Japanese-Patent No. 2011-115253, the electric motor of the said gazette is a motor with a brush. Moreover, the electric motor of the publication is a so-called inner rotor type motor in which a magnet is positioned on the inner side in the radial direction of the armature. In the inner rotor type motor, the gas sent from the impeller can flow downward through the gap of the armature. For this reason, even if the circuit board is disposed under the armature, the circuit board can be easily cooled by applying a gas to the circuit board.

  On the other hand, if a so-called outer rotor type brushless motor in which a magnet is located on the outer side in the radial direction of the armature is employed, the blower can be made smaller and more efficient. However, in the outer rotor type motor, the upper part of the armature is covered by the rotor holder that connects the shaft and the magnet. In such a structure, it becomes difficult to apply the gas sent from the impeller to the circuit board disposed below the armature.

  An object of the present invention is to provide a centrifugal fan that employs an outer rotor type motor structure and that can cool a circuit board using an airflow generated by an impeller.

  An exemplary first invention of the present application includes a stationary portion and a rotating portion that is rotatably supported with respect to the stationary portion, and the rotating portion is disposed along a central axis extending vertically. A shaft, a magnet having magnetic poles, a rotor holder that holds the magnet, and an impeller that is positioned above the rotor holder and is fixed to the shaft directly or via another member, and the stationary part A bearing member that rotatably supports the shaft, a bearing housing that holds the bearing member, an armature that is located radially outside the bearing housing and radially inside the magnet, and under the armature A circuit board positioned on the side, a mounting plate positioned on the lower side of the circuit board and fixed to the bearing housing directly or via a member different from the other members, and the rotor holder A motor holder that is located radially outside and below the impeller and fixed to the mounting plate; and a wall portion that annularly surrounds the impeller and the motor holder, and the impeller has a central axis. A plurality of blades arranged around, the wall portion is located on the radially outer side of the impeller, the impeller wall portion annularly surrounding the impeller, and located on the radially outer side of the motor holder; A motor wall that surrounds the motor holder in an annular shape, and the motor holder includes a plurality of columnar portions extending in the axial direction on the radially outer side of the rotor holder and the circuit board, and an upper end portion of the columnar portion. A radial portion between a plate-like portion that extends radially outward, an exhaust port that is located below the impeller and penetrates at least a portion of the plate-like portion in the axial direction, and a columnar portion that is above and adjacent to the mounting plate Is a centrifugal fan having a window extending through the.

  According to the first exemplary invention of the present application, the gas accelerated by the rotation of the impeller flows downward through the exhaust port. A part of the gas hits the circuit board through the window of the motor holder. For this reason, the circuit board can be cooled by employing an outer rotor type motor structure and utilizing the airflow generated by the impeller.

FIG. 1 is a longitudinal sectional view of a centrifugal fan according to the first embodiment. FIG. 2 is a longitudinal sectional view of the centrifugal fan according to the second embodiment. FIG. 3 is a bottom view of the centrifugal fan according to the second embodiment. FIG. 4 is a partial longitudinal sectional view of the centrifugal fan according to the second embodiment. FIG. 5 is a partial longitudinal sectional view of a centrifugal fan according to a modification. FIG. 6 is a partial longitudinal sectional view of a centrifugal fan according to a modification. FIG. 7 is a partial longitudinal sectional view of a centrifugal fan according to a modification.

  Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. In the present application, a direction parallel to the central axis of the centrifugal fan is referred to as an “axial direction”, a direction perpendicular to the central axis of the centrifugal fan is referred to as a “radial direction”, and a direction along an arc centered on the central axis of the centrifugal fan is referred to as “ "Circumferential direction". Further, in the present application, the shape and positional relationship of each part will be described with the axial direction being the vertical direction and the impeller side being up with respect to the rotor holder. However, this definition of the vertical direction is not intended to limit the direction when the centrifugal fan according to the present invention is used.

<1. First Embodiment>
FIG. 1 is a longitudinal sectional view of a centrifugal fan 1A according to a first embodiment of the present invention. As shown in FIG. 1, the centrifugal fan 1A has a stationary part 2A and a rotating part 3A. The rotating part 3A is supported so as to be rotatable with respect to the stationary part 2A.

  The rotating unit 3A includes a shaft 31A, a rotor holder 32A, a magnet 33A, and an impeller 34A. The shaft 31A is arranged along a central axis 9A that extends vertically. The rotor holder 32A holds a magnet 33A having a magnetic pole. Impeller 34A is located above rotor holder 32A. The impeller 34A is fixed to the shaft 31A. Further, the impeller 34A has a plurality of wings arranged around the central axis 9A.

  The stationary portion 2A includes a bearing member 21A, a bearing housing 22A, an armature 23A, a circuit board 24A, a mounting plate 25A, a motor holder 51A, and a wall portion 52A. The shaft 31A is rotatably supported by the bearing member 21A. The bearing member 21A is held by the bearing housing 22A. The armature 23A is located on the radially outer side of the bearing housing 22A and on the radially inner side of the magnet 33A. The circuit board 24A is located below the armature 23A. The mounting plate 25A is fixed to the bearing housing 22A on the lower side of the circuit board 24A.

  The motor holder 51A is located on the radially outer side of the rotor holder 32A and below the impeller 34A. The motor holder 51A is fixed to the mounting plate 25A. Impeller 34A and motor holder 51A are surrounded by annular wall 52A. The wall 52A has an impeller wall 521A and a motor wall 522A. The impeller wall portion 521A is located on the radially outer side of the impeller 34A. The motor wall 522A is located on the radially outer side of the motor holder 51A. That is, the impeller 34A is surrounded by the annular impeller wall 521A. The motor holder 51A is surrounded by an annular motor wall 522A.

  Further, as shown in FIG. 1, the motor holder 51A has a plurality of columnar portions 511A, a plate-like portion 512A, an exhaust port 514A, and a window portion 515A. The plurality of columnar portions 511A extend in the axial direction on the radially outer side of the rotor holder 32A and the circuit board 24A. The plate-like portion 512A extends radially outward from the upper ends of the plurality of columnar portions 511A. The exhaust port 514A is positioned below the impeller 34A and penetrates at least a part of the plate-like portion 512A in the axial direction. The window portion 515A penetrates the mounting plate 25A above and between the adjacent columnar portions 511A in the radial direction.

  In the centrifugal fan 1A, the gas is accelerated radially outward by the rotation of the impeller 34A. Further, the accelerated gas flows downward through the exhaust port 514A. A part of the gas hits the circuit board 24A through the window 515A of the motor holder 51A. For this reason, the circuit board 24A can be cooled by employing an outer rotor type motor structure and utilizing the airflow generated by the impeller 34A.

  The impeller 34A may be directly fixed to the shaft 31A as shown in FIG. 1, or may be fixed to the shaft 31A via another member. Further, the mounting plate 25A may be directly fixed to the bearing housing 22A as shown in FIG. 1, or may be fixed to the bearing housing 22A via a member different from the other members described above. . Further, the bearing housing 22A and the mounting plate 25A may be a single member.

<2. Second Embodiment>
<2-1. Overall configuration of centrifugal fan>
FIG. 2 is a longitudinal sectional view of the centrifugal fan 1 according to the second embodiment of the present invention. FIG. 3 is a bottom view of the centrifugal fan 1. The centrifugal fan 1 is mounted on a household or business vacuum cleaner, handy cleaner, or automatic cleaning robot, and is used as a blower that generates a suction force for sucking dust. However, the centrifugal fan of the present invention may be used for applications other than suction. For example, the centrifugal fan of the present invention may be mounted on home appliances such as an air conditioner, transportation equipment such as an automobile, OA equipment, medical equipment, etc., and generate various airflows.

  As shown in FIG. 2, the centrifugal fan 1 has a stationary part 2 and a rotating part 3. The stationary part 2 is fixed to a frame of a device on which the centrifugal fan 1 is mounted. The rotating unit 3 is supported so as to be rotatable with respect to the stationary unit 2.

  The stationary part 2 of the present embodiment includes a bearing member 21, a bearing housing 22, an armature 23, a circuit board 24, a mounting plate 25, a case member 26, and a cover member 27.

  The bearing member 21 is a mechanism that rotatably supports the shaft 31 on the rotating unit 3 side. As the bearing member 21, for example, a ball bearing that relatively rotates an outer ring and an inner ring via a sphere is used. However, other types of bearings such as a slide bearing and a fluid bearing may be used instead of the ball bearing. The bearing housing 22 is a member that holds the bearing member 21. For example, a metal such as a copper alloy is used as the material of the bearing member 21. The bearing housing 22 extends in a substantially cylindrical shape in the axial direction on the radially outer side of the bearing member 21. The outer ring of the bearing member 21 is fixed to the inner peripheral surface of the bearing housing 22.

  The armature 23 is located on the radially outer side of the bearing housing 22 and on the radially inner side of a magnet 33 described later. The armature 23 has a stator core 41, an insulator 42, and a coil 43. The stator core 41 is made of a laminated steel plate in which electromagnetic steel plates such as silicon steel plates are laminated in the axial direction. The stator core 41 has an annular core back 411 and a plurality of teeth 412 that protrude radially outward from the core back 411. The core back 411 is fixed to the outer peripheral surface of the bearing housing 22. The plurality of teeth 412 are arranged at equal intervals in the circumferential direction.

  The insulator 42 is attached to each tooth 412 of the stator core 41. The insulator 42 is made of a resin that is an insulating material. An upper surface, a lower surface, and both side surfaces in the circumferential direction of each tooth 412 are covered with an insulator 42. The coil 43 is configured by a conductive wire wound around the insulator 42. The insulator 42 is electrically insulated from the tooth 412 and the coil 43 by being interposed between the tooth 412 and the coil 43.

  The circuit board 24 is a plate-like member positioned below the armature 23 and a magnet 33 described later. An electronic circuit for supplying a drive current to the coil 43 is formed on the surface of the circuit board 24. As shown in FIG. 2, the insulator 42 of the present embodiment has a protrusion 421 that extends downward on the radially inner side of the coil 43. The circuit board 24 is held on a claw 422 provided at the lower end of the protrusion 421.

  The mounting plate 25 is a plate-like member located on the lower side of the circuit board 24. As the material of the mounting plate 25, for example, a metal such as stainless steel or aluminum is used. A through hole 251 in which the bearing housing 22 is disposed is provided at the center of the mounting plate 25. Further, the inner end portion of the mounting plate 25 constituting the through hole 251 is fixed to the outer peripheral surface of the bearing housing 22 with, for example, caulking or an adhesive.

  The case member 26 is a resin member fixed to the mounting plate. The case member 26 is obtained by, for example, injection molding. As shown in FIG. 2, the case member 26 includes a motor holder 51 and a wall portion 52. The motor holder 51 is located on the radially outer side of the rotor holder 32 described later and below the impeller 34 described later. The wall 52 surrounds the impeller 34 and the motor holder 51 in an annular shape.

  As shown in FIGS. 2 and 3, the motor holder 51 of the present embodiment has a plurality of columnar portions 511, a plate-like portion 512, and a tubular portion 513.

  The plurality of columnar portions 511 extend in the axial direction on the outer side in the radial direction of the circuit board 24 and the rotor holder 32 described later. The plurality of columnar portions 511 are arranged at substantially equal intervals in the circumferential direction. A mounting plate 25 is fixed to the lower end portion of each columnar portion 511 by screwing. However, instead of screwing, other fixing means such as caulking, welding, and adhesive may be used.

  The plate-like portion 512 extends in a plate shape from the upper end portion of the columnar portion 511 toward the radially outer side. The upper surface of the plate-like portion 512 is opposed to the lower surface of the impeller 34 described later in the axial direction with a gap therebetween. As shown in FIGS. 2 and 3, the plate-like portion 512 is provided with a plurality of exhaust ports 514. The plurality of exhaust ports 514 are located on the outer side in the radial direction from the impeller 34 described later and below the impeller 34. Each exhaust port 514 passes through the plate-like portion 512 in the axial direction.

  The cylindrical portion 513 extends in a substantially cylindrical shape downward from the end portion on the radially inner side of the plate-like portion 512. The cylindrical part 513 covers the outer peripheral surface of the rotor holder 32 described later in an annular shape. That is, the inner peripheral surface of the cylindrical part 513 is opposed to the outer peripheral surface of the rotor holder 32 in the radial direction with a gap. The plurality of columnar portions 511 are connected in the circumferential direction by a cylindrical portion 513. Thereby, the rigidity of case member 26 is improved.

  The cover member 27 is a resin member fixed to the upper portion of the wall portion 52. The cover member 27 is obtained by, for example, injection molding. As shown in FIG. 2, the cover member 27 has an upper cover portion 271 and an outer cover portion 272. The upper cover portion 271 spreads along the upper surface of the impeller 34 described later. An air inlet 273 is provided in the center of the upper cover portion 271. The intake port 273 penetrates the upper cover portion 271 vertically. The outer cover portion 272 extends in a substantially cylindrical shape from the radially outer edge of the upper cover portion 271 toward the lower side. The upper end portion of the wall portion 52 is inserted inside the outer cover portion 272 in the radial direction.

  The rotating unit 3 according to the present embodiment includes a shaft 31, a rotor holder 32, a magnet 33, and an impeller 34.

  The shaft 31 is a columnar member disposed along the central axis 9. The shaft 31 is made of a metal such as stainless steel, for example. An inner ring of the bearing member 21 is fixed to the outer peripheral surface of the shaft 31. The shaft 31 rotates around the central axis 9 while being supported by the bearing member 21. The upper end portion of the shaft 31 protrudes upward from the bearing member 21 and the rotor holder 32.

  The rotor holder 32 rotates with the shaft 31 while holding the magnet 33. The rotor holder 32 is obtained, for example, by pressing a metal such as a galvanized steel plate. As shown in FIG. 3, the rotor holder 32 of the present embodiment has a top plate portion 321 and a cylindrical portion 322. The top plate portion 321 covers the upper part of the armature 23. An end portion on the radially inner side of the top plate portion 321 is fixed to the shaft 31. However, another member may be interposed between the shaft 31 and the rotor holder 32. The cylindrical portion 322 extends in a substantially cylindrical shape downward from the radially outer edge of the top plate portion 321.

  The magnet 33 is fixed to the inner peripheral surface of the cylindrical portion 322. The magnet 33 is located on the outer side in the radial direction of the armature 23. The magnet 33 of this embodiment is formed in an annular shape. The inner peripheral surface of the magnet 33 includes a magnetic pole surface in which N poles and S poles are alternately magnetized in the circumferential direction. A plurality of magnets may be used instead of the annular magnet 33. When a plurality of magnets are used, the plurality of magnets may be arranged in the circumferential direction so that the N poles and the S poles are alternately arranged.

  The impeller 34 is positioned above the rotor holder 32 and rotates together with the shaft 31. For example, a resin is used as the material of the impeller 34. The impeller 34 has an upper curtain part 341, a lower curtain part 342, and a plurality of wings 343. A first opening 344 penetrating in the axial direction is provided at the center of the upper curtain portion 341. The first opening 344 is located below the intake port 273. The upper curtain portion 341 extends from the peripheral edge of the first opening 344 toward the radially outer side and the lower side. An end portion on the radially inner side of the lower curtain portion 342 is fixed to an upper end portion of the shaft 31 via a metal connecting member 35. The lower curtain part 342 extends from the outer peripheral surface of the connecting member 35 toward the radially outer side.

  The plurality of wings 343 are arranged around the central axis and connect the upper curtain part 341 and the lower curtain part 342 in the axial direction. Each blade 343 extends obliquely with respect to the radial direction and the circumferential direction. In addition, a second opening 345 is provided between a radially outer edge of the upper curtain 341 and a radially outer edge of the lower curtain 342. A gas flow path communicating with both the first opening 344 and the second opening 345 is provided between the plurality of blades 343.

  In such a centrifugal fan 1, when a drive current is applied to the coil 43 of the armature 23 via the circuit board 24, magnetic flux is generated in the plurality of teeth 412 of the stator core 41. A circumferential torque is generated by the action of magnetic flux between the teeth 412 and the magnet 33. As a result, the rotating unit 3 rotates about the central axis 9 with respect to the stationary unit 2.

  Further, when the rotating unit 3 rotates, the gas is accelerated by the plurality of blades 343 of the impeller 34 to generate an air flow. That is, the gas above the centrifugal fan 1 is sucked into the space between the upper curtain part 341 and the lower curtain part 342 via the air inlet 273 and the first opening 344. The gas accelerated radially outward by the plurality of blades 343 is sent to the lower side of the centrifugal fan 1 through the second opening 345 and the exhaust port 514.

<2-2. More detailed structure of case member>
Subsequently, a more detailed structure of the case member 26 will be described. FIG. 4 is a partial longitudinal sectional view of the centrifugal fan 1 in the vicinity of the case member 26. In the following, FIG. 4 will be referred to as appropriate together with FIGS.

  As described above, the case member 26 includes the motor holder 51 and the wall portion 52. As shown in FIGS. 2 and 4, the wall 52 is located on the radially outer side of the impeller 34 and the motor holder 51. That is, the wall portion 52 includes an impeller wall portion 521 located on the radially outer side of the impeller 34 and a motor wall portion 522 located on the radially outer side of the motor holder 51. The impeller wall 521 surrounds the impeller 34 in an annular shape. The motor wall 522 surrounds the motor holder 51 in an annular shape. The gas accelerated by the impeller 34 flows downward along the inner peripheral surfaces of the impeller wall portion 521 and the motor wall portion 522 as indicated by a broken line arrow 71 in FIG.

  As shown in FIGS. 2 to 4, the motor holder 51 has a plurality of window portions 515. Each window portion 515 penetrates the motor holder 51 in the radial direction above the mounting plate 25 and between adjacent columnar portions 511. For this reason, a part of the gas constituting the air flow indicated by the broken arrow 71 hits the circuit board 24 through the window 515 of the motor holder 51 as indicated by the broken arrows 73 and 74. Thereby, the circuit board 24 is cooled and the overheating of the circuit board 24 is suppressed. That is, in the centrifugal fan 1, the circuit board 24 can be cooled by employing an outer rotor type motor structure and utilizing the airflow generated by the impeller 34.

  In particular, the motor holder 51 of the present embodiment has a cylindrical portion 513. For this reason, the air flow indicated by the broken line arrow 71 thereafter flows below the cylindrical part 513 along the lower surface of the plate-like part 512 and the outer peripheral surface of the cylindrical part 513 as indicated by the broken line arrow 72. Thereby, the gas is more efficiently guided to the circuit board 24. As a result, the circuit board 24 is cooled more efficiently.

  Further, another part of the gas accelerated by the impeller 34 flows between the plate-like portion 512 and the impeller 34. And it flows between the rotor holder 32 and the cylindrical part 513 toward the downward direction like the broken-line arrow 75 in FIG. In the present embodiment, the air flow indicated by the broken line arrow 75 also hits the circuit board 24. Thereby, the circuit board 24 is cooled more efficiently.

  Further, as shown in FIG. 4, in the present embodiment, the edge portion on the radially outer side of the circuit board 24 is located on the radially outer side from the outer peripheral surface of the rotor holder 32. For this reason, the gas hits the edge of the circuit board 24 on the radially outer side more efficiently. In particular, the air flow indicated by the broken line arrow 75 strikes substantially vertically toward the upper surface of the circuit board 24. Thereby, the circuit board 24 is cooled more efficiently.

  Moreover, as shown in FIG. 4, the cylindrical part 513 of this embodiment inclines so that it may converge to radial inside as it goes below. That is, both the outer peripheral surface and inner peripheral surface of the cylindrical part 513 are inclined so as to converge radially inward as it goes downward. For this reason, the air current of the broken-line arrow 72 is guided to the circuit board 24 side more efficiently along the outer peripheral surface of the cylindrical portion 513. Further, the air flow indicated by the broken line arrow 75 is also guided to the circuit board 24 side more efficiently along the inner peripheral surface of the cylindrical portion 513.

  However, the outer peripheral surface and inner peripheral surface of the cylindrical part 513 may be a cylindrical surface without inclination. Moreover, it may replace with the cylindrical part 513 and may incline the some columnar part 511 to radial inside as it goes below. Moreover, you may incline both the cylindrical part 513 and the some columnar part 511 to radial inside as it goes below.

  As shown in FIG. 4, the circuit board 24 of the present embodiment has a plurality of switching elements 241 such as FETs constituting a part of the electronic circuit. The switching element 241 is disposed on the lower surface of the circuit board 24. If the switching element 241 is used, on / off of the drive current can be switched without using a brush. Therefore, the centrifugal fan 1 can be further downsized. However, the switching element 241 generates heat during driving. For this reason, in order to extend the service life of the circuit board 24, it is preferable that the switching element 241 is particularly efficiently cooled among the circuit boards 24.

  In this regard, in the present embodiment, the plurality of switching elements 241 are arranged in the vicinity of the edge portion on the radially outer side of the circuit board 24. Moreover, as shown in FIG. 3, the switching element 241 and the columnar part 511 are arrange | positioned in the mutually different circumferential position. For this reason, the air current of the broken line arrow 74 in FIG. 4 hits the switching element 241 without being blocked by the columnar portion 511. Thereby, the switching element 241 is cooled more efficiently.

  As shown in FIG. 4, in the present embodiment, the lower surface of the circuit board 24 and the upper surface of the mounting plate 25 are opposed to each other in the axial direction with a gap therebetween. A switching element 241 that is an electronic component is disposed on the lower surface of the circuit board 24. The air flow indicated by the broken-line arrow 74 flows between the lower surface of the circuit board 24 and the upper surface of the mounting plate 25. Thereby, the switching element 241 disposed on the lower surface of the circuit board 24 is cooled.

  Further, the circuit board 24 of the present embodiment further includes a land portion 242. The land portion 242 is disposed on the upper surface of the circuit board 24. The end portion of the conducting wire extending from the coil 43 is electrically connected to the land portion 242 by soldering. The air flow indicated by the broken-line arrow 73 flows into the upper surface side of the circuit board 24. Thereby, the land portion 242 disposed on the upper surface of the circuit board 24 is cooled.

  In the present embodiment, as shown in FIG. 4, the switching element 241 and the land portion 242 overlap in the axial direction. In this way, the land portion 242 can be widely arranged using the upper surface side of the arrangement space of the switching element 241. As a result, the electric resistance of the land portion 242 is reduced, and heat generation in the land portion 242 can be suppressed.

  Further, as shown in FIG. 4, in the present embodiment, the lower end portion of the cylindrical portion 513 is located above the lower surface of the circuit board 24. For this reason, gas tends to flow into the lower surface side of the circuit board 24 as indicated by a broken-line arrow 74 in FIG. Therefore, the gas can be applied to the lower surface of the circuit board 24 more efficiently. In the present embodiment, the lower end portion of the cylindrical portion 513 is positioned above the upper surface of the circuit board 24. For this reason, the gas easily flows into the upper surface side of the circuit board 24 as indicated by a broken line arrow 73 in FIG. Therefore, the gas can be applied to the upper surface of the circuit board 24 more efficiently.

  Further, the case member 26 of the present embodiment further includes a plurality of stationary blades 516. Each stationary blade 516 spreads downward from the lower surface of the plate-like portion 512. Further, as shown in FIG. 3, each stationary blade 516 extends in a spiral shape from the vicinity of the exhaust port 514 toward the inner side in the circumferential direction and the radial direction. Between the plurality of stationary blades 516, a flow path 517 for guiding the gas radially inward is formed. The air flow indicated by the broken-line arrow 72 in FIG. 4 flows inward in the radial direction through the flow path 517. Thereby, the gas strikes the circuit board 24 more efficiently.

  As shown in FIG. 3, in the present embodiment, the radially outer end of each stationary blade 516 is connected to the motor wall 522. Further, the radially inner end of each stationary blade 516 is connected to at least one of the columnar portion 511 and the tubular portion 513. Thereby, the gas is more efficiently guided from the exhaust port 514 to the circuit board 24. Further, the stator blade 516 further increases the rigidity of the case member 26.

  Further, as shown in FIGS. 2 and 3, the plurality of stationary blades 516 of the present embodiment have guide portions 518. The guide portion 518 constitutes a part of the edge of the exhaust port 514. In addition, the guide portion 518 extends in a spiral shape along the stationary blade 516. The height of the guide portion 518 decreases as it goes to the downstream side in the circumferential direction. The gas passing through the exhaust port 514 is efficiently guided to the flow path 517 between the adjacent stationary blades 516 by the guide portion 518.

  As shown in FIG. 2, in this embodiment, the stator core 41 and the mounting plate 25 are both directly fixed to the metal bearing housing 22. For this reason, the heat generated in the armature 23 is released to the outside through the stator core 41, the bearing housing 22, and the mounting plate 25. In particular, in the centrifugal fan 1 of the present embodiment, the gas flowing inward in the radial direction from the window portion 515 hits not only the circuit board 24 but also the mounting plate 25. Thereby, the heat of the mounting plate 25 is efficiently released to the outside.

  In the present embodiment, the circuit board 24 is fixed not on the bearing housing 22 or the mounting plate 25 that is the heat dissipation path of the armature 23 but on the claw portion 422 provided on the insulator 42. The thermal conductivity of the resin that constitutes the insulator 42 is lower than the thermal conductivity of the metal that constitutes the bearing housing 22 or the mounting plate 25. For this reason, the heat generated in the armature 23 is not easily transmitted to the circuit board 24. Thereby, the temperature rise of the circuit board 24 is further suppressed.

<3. Modification>
As mentioned above, although exemplary embodiment of this invention was described, this invention is not limited to said embodiment.

  FIG. 5 is a partial longitudinal sectional view of a centrifugal fan 1B according to a modification. In the example of FIG. 5, the cylindrical portion 513B extends without inclining in the axial direction. Moreover, the lower end part of the cylindrical part 513B is located below the lower end part of the cylindrical part 322B of the rotor holder 32B. If it does in this way, it can control that dust flows in from the diameter direction outside of cylindrical part 513B to the diameter direction inside of cylindrical part 322B. In particular, in the case of a centrifugal fan for a vacuum cleaner, dust may be contained in the airflow. If the structure of FIG. 5 is employ | adopted, it can suppress that the said dust adheres to the armature 23B. In addition, dust flows biased radially outward due to centrifugal force. For this reason, dust is not easily contained in the air current of the broken-line arrow 75B flowing between the cylindrical portion 413 and the rotor holder 32B.

  In the example of FIG. 5, the lower ends of the plurality of stationary blades 516B are located above the lower ends of the cylindrical portion 513B. In this way, the axial length of the stationary blade 516B can be suppressed as compared with the case where the lower end portion of the stationary blade 516B has a height equal to or lower than the lower end portion of the cylindrical portion 513B. As a result, the degree of freedom of attachment of the centrifugal fan 1B to the vacuum cleaner can be improved.

  FIG. 6 is a partial longitudinal sectional view of a centrifugal fan 1C according to another modification. In the example of FIG. 6, the heat transfer member 28C is interposed between the lower surface of the circuit board 24C and the upper surface of the mounting plate 25C. For the heat transfer member 28C, for example, a resin material such as a thermal tape having a higher thermal conductivity than air is used. In this way, the heat generated in the circuit board 24C can be released to the outside through the heat transfer member 28C and the mounting plate 25C. In particular, in the example of FIG. 6, the airflow indicated by the broken-line arrow 74 </ b> C flowing radially inward from the window portion 515 </ b> C hits the mounting plate 25 </ b> C. Thereby, the heat of the mounting plate 25C is efficiently released to the outside.

  FIG. 7 is a partial longitudinal sectional view of a centrifugal fan 1D according to another modification. In the example of FIG. 7, a part of the surface of the circuit board 24D is covered with an insulating coating material 29D. For the insulating coating agent 29D, for example, a resin material such as an adhesive or a potting agent is used. If it does in this way, it can control that air current is applied to circuit board 24D, and dust and a water droplet adhere to copper foil and electronic parts on circuit board 24. The insulating coating material 29D may cover the entire surface of the circuit board 24D.

  Moreover, about the detailed shape of a centrifugal fan, you may differ from each figure of this application. For example, the impeller may be directly fixed to the shaft without using a connecting member. Further, the impeller may be fixed to the shaft via the rotor holder. That is, the impeller may be fixed to the shaft directly or via another member. The mounting plate may be fixed to the bearing housing via a member different from the other members described above.

  Further, the number of columnar portions of the motor holder may be three as shown in FIG. 3, or may be 1 to 2 or 4 or more. Further, the number of the stationary blades and the exhaust ports may be different from the example of FIG. The exhaust port may be positioned below the impeller and penetrate at least a part of the plate-like portion in the axial direction.

  Moreover, you may combine suitably each element which appeared in said embodiment and modification in the range which does not produce inconsistency.

  The present invention can be used for a centrifugal fan.

1, 1A, 1B, 1C, 1D Centrifugal fan 2, 2A Static part 3, 3A Rotating part 9, 9A Central shaft 21, 21A Bearing member 22, 22A Bearing housing 23, 23A Armature 24, 24A, 24C, 24D Circuit board 25, 25A, 25C Mounting plate 26 Case member 27 Cover member 28C Heat transfer member 29D Insulating coating material 31, 31A Shaft 32, 32A, 32B Rotor holder 33, 33A Magnet 34, 34A Impeller 35 Connecting member 41 Stator core 42 Insulator 43 Coil 51 , 51A Motor holder 52, 52A Wall portion 241 Switching element 242 Land portion 273 Air inlet 343 Wing 511, 511A Columnar portion 512, 512A Plate portion 513, 513B Cylindrical portion 514, 514A Exhaust port 515, 515A Window 516,516B stator vane 517 flow path 518 guide portion 521,521A impeller wall 522,522A motor wall

Claims (18)

A stationary part;
A rotating part supported rotatably with respect to the stationary part;
Have
The rotating part is
A shaft disposed along a central axis extending vertically;
A magnet with magnetic poles;
A rotor holder for holding the magnet;
An impeller located above the rotor holder and fixed to the shaft directly or via another member;
Have
The stationary part is
A bearing member for rotatably supporting the shaft;
A bearing housing for holding the bearing member;
An armature located radially outside the bearing housing and radially inside the magnet;
A circuit board located under the armature;
A mounting plate located below the circuit board and fixed to the bearing housing directly or via a member different from the other members;
A motor holder located on the radially outer side of the rotor holder and below the impeller, and fixed to the mounting plate;
A wall portion that annularly surrounds the impeller and the motor holder;
Have
The impeller has a plurality of wings disposed around the central axis;
The wall is
An impeller wall located on the radially outer side of the impeller and surrounding the impeller in an annular shape;
A motor wall that is located radially outside the motor holder and surrounds the motor holder in an annular shape;
Have
The motor holder is
A plurality of columnar portions extending in the axial direction on the outer side in the radial direction of the rotor holder and the circuit board,
A plate-like portion extending radially outward from the upper end of the columnar portion;
An exhaust port located below the impeller and penetrating at least a portion of the plate-like portion in the axial direction;
A window portion that penetrates radially between the columnar portions above and adjacent to the mounting plate;
Having a centrifugal fan. The centrifugal fan according to claim 1,
The motor holder is
It further has a tubular portion extending in a tubular shape downward from the inner peripheral portion of the plate-shaped portion,
A centrifugal fan in which an outer peripheral surface of the rotor holder and an inner peripheral surface of the cylindrical portion are opposed to each other in a radial direction with a gap therebetween. The centrifugal fan according to claim 2,
The lower end portion of the cylindrical portion is a centrifugal fan located above the lower surface of the circuit board. The centrifugal fan according to claim 3,
The lower end part of the said cylindrical part is a centrifugal fan located above the upper surface of the said circuit board. The centrifugal fan according to claim 4,
A centrifugal fan in which an outer end portion of the circuit board is located radially outward from an outer peripheral surface of the rotor holder. The centrifugal fan according to any one of claims 2 to 5,
The lower end part of the cylindrical part is a centrifugal fan located below the lower end part of the rotor holder. The centrifugal fan according to any one of claims 2 to 6,
A centrifugal fan in which at least one of the cylindrical portion and the columnar portion is inclined radially inward as it goes downward. The centrifugal fan according to claim 1,
The stationary fan further includes a plurality of stationary blades that extend downward from a lower surface of the plate-like portion and extend from the exhaust port toward a circumferential direction and a radially inner side. The centrifugal fan according to claim 8,
The motor holder is
It further has a tubular portion extending in a tubular shape downward from the inner peripheral portion of the plate-shaped portion,
The outer peripheral surface of the rotor holder and the inner peripheral surface of the cylindrical portion are opposed to each other in the radial direction through a gap,
A centrifugal fan in which lower end parts of the plurality of stationary blades are located above the lower end part of the cylindrical part. The centrifugal fan according to claim 8,
The motor holder is
It further has a tubular portion extending in a tubular shape downward from the inner peripheral portion of the plate-shaped portion,
The outer peripheral surface of the rotor holder and the inner peripheral surface of the cylindrical portion are opposed to each other in the radial direction through a gap,
The radially outer ends of the plurality of stationary blades are connected to the motor wall,
A centrifugal fan in which the radially inner ends of the plurality of stationary blades are connected to at least one of the columnar part and the cylindrical part. The centrifugal fan according to any one of claims 8 to 10,
The plurality of stationary blades constitute a part of an edge of the exhaust port, and further include a spiral guide portion whose height decreases in the circumferential direction. The centrifugal fan according to any one of claims 1 to 11,
The lower surface of the circuit board and the upper surface of the mounting plate are opposed to each other in the axial direction through a gap,
A centrifugal fan in which electronic components are disposed on a lower surface of the circuit board. The centrifugal fan according to claim 12,
A centrifugal fan in which a heat transfer member having a higher thermal conductivity than air is interposed between a lower surface of the circuit board and an upper surface of the mounting plate. The centrifugal fan according to any one of claims 1 to 13,
The centrifugal fan in which the armature and the mounting plate are both directly fixed to the bearing housing. The centrifugal fan according to any one of claims 1 to 14,
The bearing housing and the mounting plate are each made of metal,
The armature has a resin insulator,
A centrifugal fan in which the circuit board is fixed to the insulator. The centrifugal fan according to any one of claims 1 to 15,
A centrifugal fan in which at least a part of a surface of the circuit board is covered with an insulating coating material. The centrifugal fan according to any one of claims 1 to 16,
The circuit board has a switching element,
The centrifugal fan in which the switching element and the columnar part are arranged at different circumferential positions. The centrifugal fan according to claim 17,
The circuit board further includes a land portion to which a conductive wire extending from the coil is connected,
The switching element is disposed on a lower surface of the circuit board;
The land portion is disposed on the upper surface of the circuit board,
A centrifugal fan in which the switching element and the land portion overlap in the axial direction.

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