JP2008082328A - Centrifugal fan - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a centrifugal fan capable of cooling inside of a motor without deteriorating air capacity characteristics. <P>SOLUTION: An annular hub 22 protruding in a radially outward direction is formed at a lower end part of a cylinder part of a cup part 21. A plurality of main wings 231 protruding upward are formed at an upper end surface of the hub 22. A plurality of second wings 232 protruding downward are formed at a lower end surface of the hub 22. A plurality of through holes 211 are formed at the cup part 21. Part of air flow generated by rotation of an impeller 2 is blown to inside of the cup part 21 through the plurality of through holes 211. As the plurality of second wings 232 formed at the lower surface of the hub 22 rotates around a center shaft J1, periphery of the plurality of second wings 232 becomes negative pressure compared to inside of the cup part 21. Thus, air in the cup part 21 is discharged from an opening side of the cup part 21 to a side of the plurality of second wings 232. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a structure of a centrifugal fan that forcibly cools a motor unit including a control circuit.

  Conventionally, in a centrifugal fan that sucks air in the direction of the rotation axis of the impeller and exhausts it in the radial direction, an impeller having a plurality of blades arranged in the circumferential direction around the rotation shaft is provided, and is provided at the center of the impeller. The impeller can be rotated around the rotation shaft by having a cylindrical magnetic magnet yoke press-fitted and attached to the cup-shaped portion having a field magnet on the inner surface.

  The centrifugal fan can generate a higher static pressure than an axial flow fan (a blower fan that generates an air flow in the rotation axis direction with respect to the rotation shaft of the impeller). Therefore, it is assumed that the electronic components are densely arranged in a high load, particularly in the housing, and used in an environment where the air flow is difficult to flow. Mainly, in an electronic device in which electronic components are densely arranged, the electronic components become high temperature. For this reason, the centrifugal fan is used for cooling electronic components. Of course, the centrifugal fan is also used for other purposes.

  The centrifugal fan includes an armature and a circuit component as heat generating components. These parts increase in calorific value as the rotational speed of the centrifugal fan increases. The centrifugal fan needs to set the rotational speed of the impeller so as not to exceed the allowable temperature range defined for the electronic component. Therefore, by reducing the temperature rise of the electronic components and the armature in the centrifugal fan, the rotational characteristics of the centrifugal fan can be improved, and the air flow characteristics can be improved.

  Various devices have been devised in order to suppress the performance degradation accompanying the temperature rise of the motor.

  For example, in the blower fans described in Patent Documents 1 to 4, a vent hole is formed in the base portion or the cup portion of the impeller so that air flows into the motor portion (including the armature and the circuit board) accommodated in the impeller cup portion. The structure of the axial fan and the centrifugal fan which suppress the temperature rise of an armature or an electronic component is disclosed.

JP-A-11-210700 JP 2001-132698 A JP2002-242887 JP2005-076473

  By the way, recent centrifugal fans for cooling have been rotating at high speed, and the motor current housed in the centrifugal fan increases with high-speed rotation, so the temperature rise of the armature and electronic components is ignored. It tends to increase so much that it cannot be done. When considering the demand for higher speed rotation and the use of a centrifugal fan in a high temperature environment, it is necessary to forcibly cool the armature and the electronic components.

  In the blower fans described in Patent Documents 1 to 4, a part of the air flow generated by the rotation of the impeller flows into the motor unit, thereby reducing the flow rate of the air flow for cooling the electronic device. For this reason, it is necessary to configure the centrifugal fan so that the flow rate of the airflow is not reduced even when a part of the airflow flows into the motor unit.

  The present invention has been made in view of the above problems, and in the centrifugal fan, while efficiently flowing air into the motor unit including the armature and the circuit board, the temperature of the motor unit is reduced without reducing the air flow characteristics of the centrifugal fan. The purpose is to suppress the rise.

  The present invention has been made in view of the above prior art. That is, the centrifugal fan according to claim 1 of the present invention is a centrifugal fan having a substantially lid-shaped cylindrical cup portion having a lid portion on the upper side in the central axis direction and an opening portion on the lower side with the central axis as a center. An impeller comprising a plurality of wings arranged annularly around the central axis on the outside of the cup part, and accommodated inside the cup part, and rotates the impeller around the central axis A motor unit that sucks air in the direction of the central axis from the upper side of the cup unit and exhausts air in a direction away from the central axis, and a circuit that is provided integrally with the motor unit and that controls the rotation of the motor unit At least one through-hole that allows communication between the outside and inside of the cup portion, and protrudes downward from the lower surface of the opening side of the cup portion. The wing or the wing Characterized in that it has a different second wing.

  A centrifugal fan according to a second aspect of the present invention is the centrifugal fan according to the first aspect, wherein the blade or the second blade is formed at a position facing the circuit board in a radial direction. Features.

  A centrifugal fan according to a third aspect of the present invention is the centrifugal fan according to the first or second aspect, wherein the through-hole is formed in a lid portion of the cup portion.

  A centrifugal fan according to a fourth aspect of the present invention is the centrifugal fan according to any one of the first to third aspects, and is substantially annular so as to protrude radially outward from an outer surface of the cup portion. A hub is formed, and the blade is supported by the hub.

  A centrifugal fan according to a fifth aspect of the present invention is the centrifugal fan according to any one of the first to fourth aspects, wherein the plurality of blades are arranged on an upper surface of the hub in the central axis direction. And at least one of the plurality of blades protrudes downward from a lower surface of the hub in the central axis direction.

  A centrifugal fan according to a sixth aspect of the present invention is the centrifugal fan according to any one of the first to fifth aspects, wherein the plurality of blades are arranged on an upper surface of the hub in the central axis direction. The second wing is arranged on the surface side opposite to the upper side of the hub in the central axis direction.

  A centrifugal fan according to a seventh aspect of the present invention is the centrifugal fan according to any one of the first to sixth aspects, wherein the hub is formed near an end of the cup portion on the opening side. Features.

  A centrifugal fan according to an eighth aspect of the present invention is the centrifugal fan according to any one of the first to seventh aspects, wherein a circuit board is disposed below an end portion on the opening side of the cup portion. It is characterized by being.

  A centrifugal fan according to a ninth aspect of the present invention is the centrifugal fan according to any one of the first to eighth aspects, wherein the through-holes are substantially equally disposed at a plurality of locations around the central axis. It is characterized by.

  A centrifugal fan according to a tenth aspect of the present invention is the centrifugal fan according to the ninth aspect, wherein the centrifugal fan is cut by a cylindrical surface centered on the central axis between the adjacent through holes of the lid portion. The cross section is formed into a blade cross section that is inclined downward as it goes from the front to the rear in the rotation direction of the impeller.

  A centrifugal fan according to an eleventh aspect of the present invention is the centrifugal fan according to any one of the first to tenth aspects, wherein the impeller has a plurality of the blades and a plurality of the second blades, When the impeller is viewed from the central axis direction, the inclination angle with the radial direction at the outer peripheral end of the blade is substantially the same as the inclination angle with the radial direction at the outer peripheral end of the second blade. Features.

  A centrifugal fan according to a twelfth aspect of the present invention is the centrifugal fan according to any one of the first to eleventh aspects, wherein the centrifugal fan has a casing, and the casing has an outer periphery of the impeller. A side wall portion in which an exhaust port is formed, an opening side of the cup portion, a base portion for supporting the motor portion, a cover on the lid portion side of the cup portion, and a cover in which an intake port is formed And a portion.

  According to the centrifugal fan described in the present invention, an air flow generated with the rotation of the impeller flows into the motor portion through the through hole formed in the impeller cup portion, and the armature and the circuit board are cooled. Since the pressure near the impeller is lower than the inside of the impeller cup part, the blades protrude toward the opposite side of the intake side than the opening part of the impeller cup part, so that the air inside the impeller cup part is With the rotation of the impeller, the impeller is discharged to the outside of the impeller cup portion, and is flowed radially outward by the impeller. That is, by a series of operations, an air flow is generated inside the impeller cup portion, and the cooling efficiency of the armature and the circuit board is improved.

  Hereinafter, a centrifugal fan according to an embodiment of the present invention will be described with reference to FIGS. 1 to 9. In the embodiment of the present invention, the vertical direction of each drawing is referred to as the “vertical direction” for convenience, but the direction in the actual mounting state is not limited.

  FIG. 1 is a diagram showing a configuration of a centrifugal fan 1 according to an embodiment of the present invention, and shows a longitudinal sectional view cut along a plane including a central axis J1. FIG. 2 is a perspective view showing the centrifugal fan 1 of the present invention. As shown in FIG. 1, the centrifugal fan 1 includes an impeller unit 2 that generates an air flow by rotating, and a motor unit 3 that is connected to the impeller unit 2 and rotates around the central axis J <b> 1. The impeller unit 2 and the motor unit 3 are accommodated in the casing 10. As shown in FIG. 1 and FIG. 2, the casing 10 is assembled by attaching a cover portion 12 having an intake port 121 to the side wall portion 101 of the casing 10, and surrounds the periphery of the impeller portion 2. (That is, the flow direction is formed in the air flow generated by the rotation of the impeller 2 and the air is discharged to the outside). The centrifugal fan 1 is used, for example, as an electric fan for cooling electrical products and electronic devices.

  As shown in FIG. 1, the casing 10 includes a base portion 102 and a side wall portion 101. At the center of the base portion 102, a bearing housing 310 is fixed so as to be coaxial with the rotation axis of the impeller portion 2, that is, the central axis J1. Further, the side wall portion 101 is formed so as to protrude continuously from the outer peripheral portion of the base portion 102 toward the upper side in the direction of the central axis J1. As shown in FIG. 2, an exhaust port 103 is formed in the side wall 101, and an air flow generated by the rotation of the impeller 2 is discharged from the centrifugal fan 1 through the exhaust port 103. As described above, the cover portion 12 is attached to the upper end of the side wall portion 101. The intake port 121 formed in the cover part 12 is substantially circular. When the cover portion 12 is attached to the casing 10, the center of the air inlet 121 is configured to overlap the central axis J1. However, the center of the intake port 121 and the central axis J1 do not necessarily overlap, and the center of the intake port 121 may be shifted from the central axis J1.

  The shape of the casing 10 is formed in a cochlear shape as seen from the direction of the central axis J1 as shown in FIG. Between the outer periphery of the impeller 2 and the inner peripheral surface of the side wall portion 101, a flow path for airflow generated by the rotation of the impeller is formed. The flow path is formed so that the cross-sectional area of the cross section of the flow path cut by a plane including a line segment parallel to the radial direction gradually increases from the upstream toward the exhaust port 103. However, the cross-sectional area of the flow path may be substantially the same from the upstream toward the exhaust port 103 in consideration of the size of the centrifugal fan and the air flow characteristics, and the shape of the flow path is not limited to the above. By forming the casing shape into a cochlea shape, it is possible to rectify the air flow generated by the rotation of the impeller 2 and to adjust the flow velocity direction of the air flow from the exhaust port. It is also possible to improve the pressure difference (static pressure) between the intake port 121 and the exhaust port side 103.

  As shown in FIG. 1, the motor unit 3 is an outer rotor type (a type in which a rotor magnet 322 included in the motor is positioned radially outward from the stator unit 31). The motor unit 3 mainly includes a rotor unit 32 that is a rotating body, a stator unit 31 that is a stationary body, and a bearing unit. The rotor part 32 is rotatably supported by a bearing part described later with respect to the stator part 31.

  The stator portion 31 is fixed to the outer surface of a bearing housing 310 in which a bearing portion described later is accommodated. The stator portion 31 mainly includes a stator core 311, first and second insulators 312 a and 312 b, a coil 313, and a circuit board 314.

The stator core 311 is configured by stacking a plurality of stator laminations formed of thin magnetic materials. In particular, the centrifugal fan 1 of the present embodiment used for cooling electronic devices employs a single-phase bipolar or a two-phase unipolar as a driving method. In single-phase bipolar and two-phase unipolar, a 4-pole stator core is used. Therefore, the stator core 311 in this embodiment is configured by an annular core back portion and four magnetic pole teeth. The magnetic pole teeth 4 protrude outward from the outer surface of the core back portion in the radial direction, and are arranged in the circumferential direction with the central axis J1 as the center.

  The periphery of the stator core 311 is covered with an insulator 312 except for the outer surface and the inner surface. The first insulator 312 a covers the stator core 311 from above, and the second insulator 312 b covers the stator core 311 from below. A coil 313 is formed by winding a copper wire around the magnetic pole teeth of the stator core 311 via an insulator 312.

  A circuit board 314 supported by being connected to the second insulator 312b is disposed below the stator core 311. The circuit board 314 includes a board and circuit components. A conductive pattern formed of copper foil is printed on the substrate so that a control circuit is configured by mounting circuit components. Circuit components are mounted on the substrate, and the control circuit and the end of the copper wire constituting the coil 313 are electrically connected to the circuit substrate 314.

  The rotor part 32 includes an impeller 2, a rotor yoke 321, a rotor magnet 322, and a shaft 323. The impeller 2 includes a covered cylindrical cup portion 21, an annular hub 22, and a plurality of wings 23. A detailed configuration regarding the impeller 2 will be described later.

  A shaft 323 is fixed at the center of the cup portion 21 so as to be coaxial with the central axis J1. The impeller 2 rotates around the central axis J1 with the shaft 323 as a rotation axis. A cylindrical rotor yoke 321 is fixed to the inner surface of the cylindrical portion of the cup portion 21. Further, an annular rotor magnet 322 is fixed to the inner surface of the rotor yoke. The rotor magnet 322 is magnetized so that a plurality of magnetic poles are alternately arranged in the circumferential direction. The rotor yoke 321 is made of a magnetic material. Since the rotor yoke 321 is configured, the magnetic field formed by the rotor magnet 322 can be prevented from leaking from the blower fan 1 to the outside. The rotor magnet 322 is disposed so as to face the outer peripheral surface of the stator core 311 in the radial direction. Therefore, when a current is supplied to the circuit board 314 from an external power source, a magnetic field is generated in the stator core 311, and the central axis J <b> 1 is centered by the interaction between the magnetic field and the magnetic field formed in the rotor magnet 322. Torque is generated. Along with this, the impeller 2 rotates around the central axis J1.

  The shaft 323 has an upper end fixed to the cup portion 21 and protrudes downward from the cup portion 21. Ball bearings 315 and 316 are fixed to the inner surface side of the bearing housing 310. The shaft 323 is rotatably supported by being inserted into the ball bearings 315 and 316. Near the upper end of the shaft 323, a spring 317 is attached to the upper side of the ball bearing 315 in the direction of the central axis J1. A retaining member 318 is attached to the vicinity of the lower end of the shaft 323 so that the shaft 323 does not come off from the ball bearing 316. Since the retaining member 318 is configured to be displaced in the central axis J1 direction with respect to the spring 317, a preload is applied to the ball bearings 315 and 316 by the spring 317. As a result, the ball bearings 315 and 316 and the shaft 323 are held in the correct positions.

  Next, the configuration of the impeller 2 will be described. An annular hub 22 that protrudes radially outward is formed at the lower end of the cylindrical portion of the cup portion 21. A plurality of main wings 231 are formed on the upper end surface of the hub 22 so as to protrude upward, and are equally distributed around the central axis J1. A plurality of second blades 232 are formed on the lower end surface of the hub 22 so as to protrude downward and are equally distributed around the central axis J1.

  The impeller 2 rotates about the central axis J1, whereby a centrifugal force acts on the air in the vicinity of the plurality of main wings 231, and the air is discharged radially outward. Accordingly, the vicinity of the plurality of main wings is in a negative pressure state around the cup portion 21 and the vicinity of the intake port 121, and air is taken from the intake port 121 toward the inside of the centrifugal fan 1. Therefore, when the impeller 2 rotates, an air flow is generated so as to be sucked in the direction of the central axis J1 and exhausted radially outward. The generated air flow is guided from the intake port 121 to the exhaust port 103 through an air flow path constituted by the casing 10 and the cover portion 12.

  FIG. 3 is a view showing a modification of the motor unit and the impeller of the centrifugal fan 1 according to the present embodiment, and shows a longitudinal sectional view cut along a plane including the central axis J1. In the centrifugal fan 1 of the present embodiment, a shaft 323 is fixed to the cup portion 21 of the impeller 2 as shown in FIG. As a modification, the following configuration is also conceivable. For example, as shown in FIG. 3, a lid portion may be formed at the upper end portion of the rotor yoke 321, and the shaft 323 may be fixed at the center of the lid portion so as to be coaxial with the central axis J1. That is, the cup part in the present invention may be the cup part 21 configured integrally with the plurality of blades 23 shown in FIG. 1 or may be the cup part constituted by the rotor yoke 321A shown in FIG. As long as the impeller has a cup-shaped part in which the motor part 3 is accommodated, the parts constituting the cup part are not limited.

  The centrifugal fan 1 generates heat in the circuit components and the coil 313 mounted on the circuit board 314 as the impeller 2 rotates. In particular, the heat generation amount increases as the rotational speed of the impeller 2 increases. In the conventional centrifugal fan, the generated heat stays in and around the coil 313 and the circuit component, so that the temperature rise of the coil 313 and the circuit component has been a problem. Therefore, in the present invention, a plurality of through holes 211 are formed in the cup portion 21. As shown in FIG. 2, the plurality of through-holes 211 are annularly arranged around the central axis J1. Accordingly, a part of the air flow generated by the rotation of the impeller 2 passes through the plurality of through holes 211 and is blown into the cup portion 21. Usually, since the temperature of the air outside the cup part 21 is lower than the temperature of the air inside the cup part 21, the air is blown into the cup part 21, so that the inside of the coil 313 and the circuit component And the heat staying around moves to the blown air stream. Thereby, the temperature rise of the coil 313 and the circuit components can be suppressed. In another modification, the through hole 3211 is formed in the lid portion of the rotor yoke 321A as shown in FIG. In short, as long as the through-hole is formed at a position where air flows between the motor unit housed inside the cup unit and the outside, the site and parts formed are not limited.

  Further, the plurality of second wings 232 formed on the lower surface of the hub 22 rotate around the central axis J <b> 1, thereby causing a negative pressure state around the plurality of second wings 232 rather than inside the cup portion 21. Therefore, the air inside the cup part 21 is discharged from the opening side of the cup part 21 to the plurality of second blades 232 side. Since the plurality of second blades 232 are formed so as to protrude downward in the direction of the central axis J1 from the opening-side end portion of the cup portion 21, an air flow path from the inside of the cup portion 21 to the plurality of second blades 232 is formed. Thus, the air staying inside the cup portion 21 can be positively released to the outside. Since the plurality of second blades 232 and the plurality of through holes 211 are formed, the inside of the cup portion 21 becomes the second air flow path. Therefore, the motor unit 3 can be actively cooled. A discharge portion from the inside of the cup portion 21 to the outside of the cup portion 21 is a gap between the rotor portion 32 and the circuit board 314 in the central axis J1 direction. Therefore, if the second blade 232 is formed at a position facing the gap in the radial direction, the air can be guided from the inside of the cup portion 21 to the outside of the cup portion 21 by the rotation of the impeller 2.

  FIG. 4 is a plan view of the impeller 2 as viewed from the intake side in the direction of the central axis J1. FIG. 5 is a plan view of the impeller 2 as viewed from the base portion 102 side in the direction of the central axis J1 (however, details inside the cup portion 21 are omitted). The plurality of main wings 231 are curved toward the front side in the rotational direction as they go from the radially inner side to the outer side. That is, the plurality of main wings 231 are formed on the upper surface of the hub 22 such that the convex surface faces the rear side in the rotation direction. The plurality of second blades 232 are curved toward the front side in the rotational direction as they go from the radially inner side to the outer side. That is, the plurality of second blades 232 are formed on the lower surface of the hub 22 such that the convex surface faces the rear side in the rotation direction.

  In the present embodiment, the number of blades formed by the main wing 231 and the second wing 232 is the same. Further, the main wing 231 and the second wing 232 are configured to substantially overlap each other when viewed from the direction of the central axis J1. However, the number of blades of the main blade 231 and the second blade 232 may be different in consideration of the air flow characteristics and the air flow characteristics of the centrifugal fan 1 to the cup portion 21. Further, the main wing 231 and the second wing 232 do not necessarily overlap each other when viewed from the direction of the central axis J1.

  An acute angle angle between a tangent of the surface on the front side in the rotational direction on the radially outermost side of the main wing 231 and a straight line connecting the intersection of the central axis J1 and the tangent and the main wing 231 is β1. Next, the angle on the acute angle side between the tangent of the surface on the front side in the rotational direction on the radially outermost side of the second blade 232 and the straight line connecting the center axis J1 and the intersection of the tangent and the second blade 232 is β2. . At this time, β1 and β2 are set to have the same angle. As a result, when the number of blades of the main wing 231 and the second wing 232 is the same and the blade shapes are substantially the same, the air flow discharge characteristics by the respective blades are the same, so the air flow passes through the cup portion 21. It is possible to suppress a reduction in the air flow characteristic of the centrifugal fan 1 due to the passage.

  FIG. 6 is a diagram showing a cross-sectional shape of the present embodiment taken along CC ′ in FIG. FIG. 7 is a diagram showing a cross-sectional shape of another modified example of the present embodiment cut along CC ′ in FIG. 4.

  6 and 7 will be described in detail. A line segment connecting C and C ′ is a part of the circumference passing through the plurality of through holes 211 with the central axis J1 as the center. In the present embodiment, as shown in FIG. 6, the CC ′ cross section is formed in a rectangular shape. With this cross-sectional shape, the inside of the cup portion 21 can be sufficiently cooled. However, as another modification, the cross section taken along the line C-C ′ may have a blade cross section as shown in FIG. 7. More specifically, the CC ′ cross section is inclined from the upper side in the central axis J1 direction to the lower side as it goes from the front side in the rotation direction to the rear side. Therefore, in another modification, as the impeller 2 rotates, the air flow that passes through the through hole 211 is pushed downward by the lower surface 213 between the through holes 211 of the lid portion in the central axis J1 direction. Promote the flow. Further, the upper surface 214 between the through holes 211 of the lid part facilitates air flow into the through holes 211.

  In addition, by forming the CC ′ cross section into a blade cross-sectional shape, it is possible to reduce the induction of the peeling phenomenon at the corner portion of the inner peripheral surface defining the through hole 211 when air passes through the through hole 211. There is concern about the energy loss of the air flow and the generation of noise due to the induction of the separation phenomenon. However, it is possible to suppress the occurrence of the peeling phenomenon by forming the CC ′ section in the blade section shape.

  Next, a description will be given of another modified centrifugal fan relating to the configuration of the main wing and the second wing. FIG. 8 is a diagram showing a configuration of another modified example related to the blade shape of the centrifugal fan 1 according to the embodiment of the present invention, and shows a longitudinal sectional view cut along a plane including the central axis J1. FIG. 9 is a diagram showing a configuration of another modification example of the blade shape of the centrifugal fan 1 according to the embodiment of the present invention, and shows a longitudinal sectional view cut along a plane including the central axis J1.

  In the modification according to the embodiment, as shown in FIG. 8, the main wing 231B may protrude downward from the lower end surface of the hub 22 in the direction of the central axis J1. In other words, the main wing 231 and the second wing 232 in FIG. 1 are formed at the same position when viewed from the direction of the central axis J1, and are connected in the radially outward direction of the hub 22. That is, the main wing 231B shown in FIG. 8 or the second wing 232 shown in FIG. 1 may protrude from the lower end surface side of the hub 22.

  As another modification according to the embodiment, as shown in FIG. 9, the hub 22 may not be formed, and the main wing 231 </ b> C may be formed directly on the outer surface of the cup portion 21. . However, a part of the main wing 231C is located below the lower end portion on the opening side of the cup portion 21 so that the air inside the cup portion 21 is discharged to the outside by rotating the main wing 231C around the central axis J1. It needs to protrude. With this configuration, even if there is no hub 22, the air staying inside the cup part 21 is discharged outside the cup part 21.

  The configurations of the main wing and the second wing are not limited to the above-described embodiments and modifications, and combinations thereof may be employed. Further, if a part of the wing protrudes below the lower end portion on the opening side of the cup portion 21, air passes through the motor portion 3 from the through hole 211 formed in the cup portion 21, and the cup portion 21. It is discharged from the opening side to the outside of the cup portion 21. If it has the structure of the wing | blade shown above, a shape and a structure are not limited to embodiment shown above.

It is sectional drawing which shows the structure of the centrifugal fan 1 which concerns on embodiment of this invention. 1 is a perspective view showing a centrifugal fan 1 according to an embodiment of the present invention. It is sectional drawing which shows the modification of the motor part and impeller of the centrifugal fan 1 which concerns on embodiment of this invention. It is the top view which looked at the impeller 2 which concerns on embodiment of this invention from the intake side in the central-axis J1 direction. It is the top view which looked at the impeller 2 which concerns on embodiment of this invention from the base part 102 side in the central-axis J1 direction. It is sectional drawing which shows the cross-sectional shape of this embodiment cut | disconnected by CC 'in FIG. 4 concerning embodiment of this invention. It is sectional drawing which shows the cross-sectional shape of the other modification of this embodiment cut | disconnected by CC 'in FIG. 4 which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the modification of the centrifugal fan which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the other modification of the centrifugal fan which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Centrifugal fan 10 Casing 101 Side wall part 102 Base part 103 Exhaust port 12 Cover part 121 Inlet port 2 Impeller 21 Cup part 211 Through-hole 22 Hub 23 Blade 231 Main wing 232 Second wing 3 Motor part 31 Stator part 314 Circuit board

Claims (12)

A centrifugal fan,
A substantially covered cylindrical cup portion having a lid portion on the upper side in the central axis direction and an opening portion on the lower side, with the central axis as a center;
A plurality of wings arranged annularly around the central axis outside the cup portion;
An impeller comprising:
A motor unit that is housed inside the cup unit, rotates the impeller about the central axis, sucks air in the central axis direction from the upper side of the cup unit, and exhausts air in a direction away from the central axis;
A circuit board provided integrally with the motor unit and provided with a circuit for controlling rotation of the motor unit;
With
The cup part has at least one through-hole that allows communication between the outside and the inside of the cup part, and the wing or the wing protrudes downward from the lower surface on the opening side of the cup part. A centrifugal fan having a second wing different from the first wing.   The centrifugal fan according to claim 1, wherein the blade or the second blade is formed at a position facing the circuit board in a radial direction.   The centrifugal fan according to claim 1, wherein the through-hole is formed in a lid portion of the cup portion.   4. A substantially annular hub is formed so as to protrude radially outward from the outer surface of the cup portion, and the blade is supported by the hub. A centrifugal fan according to any one of the above.   The plurality of blades are arranged on the upper surface of the hub in the central axis direction, and at least one of the plurality of blades is lower than the lower surface of the hub in the central axis direction. The centrifugal fan according to any one of claims 1 to 4, wherein the centrifugal fan projects toward the center.   The plurality of blades are arranged on an upper surface of the hub in the central axis direction, and the second blade is arranged on a surface opposite to the upper side of the hub in the central axis direction. A centrifugal fan according to any one of claims 1 to 5.   The centrifugal fan according to any one of claims 1 to 6, wherein the hub is formed near an end of the cup portion on an opening side.   The centrifugal fan according to any one of claims 1 to 7, wherein a circuit board is disposed below an end portion on the opening side of the cup portion.   The centrifugal fan according to any one of claims 1 to 8, wherein the through-holes are substantially equally distributed at a plurality of locations around the central axis.   Between the through holes adjacent to each other in the lid portion, a cross section cut by a cylindrical surface centering on the central axis is a blade cross section inclined downward from the front to the rear in the rotation direction of the impeller. The centrifugal fan according to claim 9, wherein the centrifugal fan is formed.   The impeller includes a plurality of the wings and a plurality of the second wings, and when the impeller is viewed from the central axis direction, an inclination angle with a radial direction at an outer peripheral end of the wings, and the second The centrifugal fan according to any one of claims 1 to 10, wherein an inclination angle with a radial direction at an outer peripheral end of the blade is substantially the same. The centrifugal fan has a casing,
The casing is
A side wall portion covering the outer periphery of the impeller and having an exhaust port;
A base portion that covers the opening side of the cup portion and supports the motor portion;
A cover part that covers the lid part side of the cup part and has an air inlet;
The centrifugal fan according to claim 1, wherein the centrifugal fan is provided.

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