JP5414392B2 - Centrifugal fan - Google Patents

Description

  The present invention relates to a centrifugal fan used for a blower or the like.

  A centrifugal fan used as a cooling fan for electronic devices or the like discharges air sucked in an axial direction in a radial direction by rotating a plurality of blades arranged in a circumferential direction with respect to a rotating shaft by a motor. It is configured.

  In order to increase the cooling effect of electronic devices and the like, it is necessary to increase the air volume of the centrifugal fan. As a means for that purpose, it is conceivable to increase the size of the blades. However, when the blade size is increased, a load for rotating the motor is increased, which causes a problem that heat generation of the electronic component mounted on the circuit board disposed in the motor is increased.

Patent Document 1 describes a technique in which a step portion is provided radially outward of a base portion that supports a motor, and an air flow path is expanded in the axial direction so as to increase the air volume. According to this technique, the effect of increasing the air volume can be obtained without increasing the size of the blades, and therefore, it is possible to suppress an increase in heat generation of the electronic component accompanying an increase in rotational load.
JP 2004-92489 A

  The blades of the centrifugal fan are fixed to a cylindrical rotor holder that rotates about a rotation axis, and rotate with the rotation of the rotor holder. And the circuit board which mounted the electronic component which drives a motor is arrange | positioned inside a rotor holder.

  In Patent Document 1, since the gap between the blade and the base portion is small in the step portion provided in the base portion, the air flowing in the axial direction due to the rotation of the blade is less likely to flow toward the circuit board. . As a result, the effect of cooling the circuit board is reduced, so that increasing the number of blade rotations in order to increase the air volume causes a problem that heat generation of the electronic component increases.

  This invention is made | formed in view of this point, and it aims at providing the centrifugal fan which has the structure which improved the cooling effect of the circuit board.

  A centrifugal fan according to one aspect of the present invention includes a substantially cylindrical rotor portion that rotates about a rotation axis, an annular connecting portion that is fixed to the rotor portion and extends radially outward of the rotor portion, and is fixed to the connecting portion. A plurality of blades arranged in the circumferential direction of the rotor portion on the outer side in the radial direction of the rotor portion, a bearing portion that rotatably supports the rotor portion, a bearing holding portion that holds the bearing portion, and a bearing holding portion. A substantially disk-shaped base portion that is fixed, a stator portion that is disposed on the inner peripheral side of the rotor portion and is fixed to the bearing holding portion, and a circuit board that is disposed between the base portion and the stator portion. The base portion includes a substantially annular convex portion projecting toward the base portion side end portion of the blade on the radially outer side of the rotor portion, and the radial inner peripheral surface of the annular convex portion is formed between the connecting portion and the blade. It is located radially outward from the fixed end.

  With such a configuration, the air flowing in the axial direction by the rotation of the blades is guided along the radially inner circumferential surface of the annular convex portion and guided to the circuit board side, so that the cooling effect of the circuit board can be improved. Therefore, even if the number of blades is increased to increase the air volume, heat generation of the electronic component can be suppressed.

  The centrifugal fan according to one aspect of the present invention can efficiently guide the air flowing in the axial direction to the circuit board side by the rotation of the blades. Therefore, it is possible to provide a centrifugal fan having a structure in which the circuit board cooling effect is enhanced.

It is sectional drawing which showed typically the structure of the centrifugal fan in one Embodiment of this invention. It is sectional drawing which showed typically the structure of the centrifugal fan in other embodiment of this invention. (A)-(c) is the fragmentary sectional view which showed the modification of the cyclic | annular convex part in this embodiment. It is sectional drawing which showed typically the structure of the centrifugal fan in other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the description of the present embodiment, for the sake of convenience, the vertical direction of each drawing is referred to as the “vertical direction”, but it does not mean the direction in the actual mounting state. In the description of the present embodiment, the direction parallel to the rotation axis is referred to as “axial direction”, and the radial direction centered on the rotation axis is referred to as “radial direction”. In addition, this invention is not limited to the following embodiment. Moreover, it can change suitably in the range which does not deviate from the range which has the effect of this invention. Furthermore, combinations with other embodiments are possible.

  FIG. 1 is a cross-sectional view schematically showing the configuration of a centrifugal fan 100 in one embodiment of the present invention.

  As shown in FIG. 1, the centrifugal fan 100 according to this embodiment includes a substantially cylindrical rotor portion 2 that rotates about a rotation axis J, a stator portion 3 that is disposed on the inner peripheral side of the rotor portion 2, and a rotor. And a plurality of blades 6 arranged in the circumferential direction of the portion 2.

  Here, the rotor portion 2 is fixed to the substantially covered cylindrical rotor holder 21, the field magnet 22 fixed to the inner side of the side wall portion of the rotor holder 21, and the central portion of the rotor holder 21. And a rotating shaft 23.

  In addition, an annular connecting portion 5 that extends outward in the radial direction of the rotor portion 2 is fixed to the rotor portion 2, and the circumferential direction of the rotor portion 2 is connected to the connecting portion 5 in the radially outward direction of the rotor portion 2. A plurality of blades 6 arranged in the same manner are fixed. In the present embodiment, the plurality of blades 6 are fixed apart from the outer peripheral surface of the rotor portion 2.

  Here, it is sufficient that the annular connecting portion 5 has a function of fixing the plurality of blades 6 in the circumferential direction of the rotor portion 2, and the form in which the connecting portion 5 is fixed to the rotor portion 2 is not limited. In the present embodiment, the connecting portion 5 is formed integrally with a substantially covered cylindrical impeller cup 5 b fixed to the outer peripheral surface of the rotor holder 21. The shaft 23 may be fixed to the central portion of the impeller cup 5b instead of being fixed to the rotor holder 21.

  The rotor portion 2 is rotatably supported by the bearing portion 4 via the shaft 23, and the bearing portion 4 is fixed to the bearing holding portion 7. Further, the bearing holding portion 7 is fixed to a substantially disc-shaped base portion 8. In the present embodiment, the base portion 8 is constituted by the bottom portion of the housing 12 that houses the motor and the blades 6, and the bearing portion 4 is constituted by a ball bearing.

  The stator unit 3 is disposed on the inner peripheral side of the rotor unit 2 and is fixed to the bearing holding unit 7, and a circuit that controls the rotational drive of the motor between the base unit 8 and the stator unit 3. A substrate 9 is provided.

  In the present invention, as shown in FIG. 1, the base portion 8 includes a substantially annular convex portion 10 that protrudes toward the base portion 8 side end portion (lower end portion) of the blade 6 on the radially outer side of the rotor portion 2. The radial inner peripheral surface 10 a of the annular convex portion 10 is located radially outward from the fixed end 5 a of the connecting portion 5 and the blade 6.

  By providing such an annular convex portion 10 on the base portion 8, a part of the air flowing in the axial direction by the rotation of the blades 6 is, as shown in FIG. 1, the radially inner peripheral surface 10 a of the annular convex portion 10. Are guided to the circuit board 9 side. Thereby, since the cooling effect of the circuit board 9 is improved, the heat generation of the electronic component mounted on the circuit board 9 can be suppressed.

  Furthermore, in another embodiment of the present invention, as shown in FIG. 2, the base portion 8 side end portion (lower end portion) of the blade 6 is provided with an extending portion 6a extending radially outward in the base portion 8 side. To the configuration. Thereby, the air flowing into the circuit board 9 side can be discharged toward the flow path, and the cooling effect of the circuit board 9 can be further enhanced. Further, the axial air flow along the extending portion 6a can also be increased.

  In addition, since the extension | stretching part 6a has a lower intensity | strength than another site | part, there exists a possibility that a vibration may generate | occur | produce when rotating. Therefore, as shown in FIG. 2, it is preferable to provide the reinforcing ring 12 over the entire circumference on the radially outer side of the extending portion 6a. Thereby, the intensity | strength of the extending | stretching part 6a increases and it can suppress the vibration at the time of rotation.

  By the way, the basic structure of the motor used for a centrifugal fan and an axial fan is common. The circuit board 9 is disposed below the stator unit 3. However, in the axial fan, if the outer diameter of the circuit board 9 is larger than the outer diameter of the rotor unit 2, airflow is hindered. Is normally disposed within the outer diameter of the rotor portion 2. Therefore, in the centrifugal fan, it is common to arrange the circuit board 9 so as to be accommodated within the outer diameter of the rotor portion 2 from the design concept shared by the motor parts.

  On the other hand, the annular convex portion 10 provided on the base portion 8 in the present invention is arranged at a position away from the outer peripheral surface of the rotor portion 2 in the radial direction. Therefore, as shown in FIG. 2, the circuit board 9 can be arranged with its radially outer peripheral end enlarged to the vicinity of the radially inner peripheral surface 10 a of the annular protrusion 10. Even if the circuit board 9 is enlarged and arranged as described above, as shown in FIG. 2, it is not hindered to guide the air flowing in the axial direction to the circuit board 9 side by the rotation of the blade 6. Therefore, by increasing the diameter of the circuit board 9, it has been possible to change what has conventionally been mounted on both sides of the electronic component to single-sided mounting. Furthermore, with the change to single-sided mounting, the circuit board 9 can also be changed from a conventional glass / epoxy board or glass / composite board to an inexpensive paper phenol board. In addition, although the example which mounted the electronic component 11 in the base part 8 side (lower surface) of the circuit board 9 is shown in FIG. 2, not only this but what is necessary is just to mount in any one surface.

  In the present invention, a part of the air flowing in the axial direction by the rotation of the blades 6 is guided along the radial inner peripheral surface 10a of the annular convex portion 10 and guided to the circuit board 9 side. Therefore, in order to make air induction smoother, the radially inner peripheral surface 10a of the annular convex portion 10 is inclined toward the radially inner upper surface of the base portion 8 as shown in FIGS. It is preferable. Moreover, the radial direction outer peripheral surface 10b of the cyclic | annular convex part 10 can make the flow of the air by which the flow path was expanded in the axial direction more smoothly by having the same inclination.

  The annular convex portion 10 provided on the base portion 8 preferably has the shape as described above, but the radial inner peripheral surface 10a of the annular convex portion 10 is formed by the connecting portion 5 and the blade 6. The shape of the annular convex portion 10 can be appropriately changed according to the required performance.

  3A to 3C are partial cross-sectional views showing modified examples of the annular protrusion 10. FIG. 3A shows an example in which the radial inner peripheral surface 10 a of the annular convex portion 10 is inclined and the radial outer peripheral surface 10 b is perpendicular to the base portion 8. FIG. 3B is a diagram in which both the radially inner peripheral surface 10 a and the outer peripheral surface 10 b of the annular convex portion 10 are perpendicular to the base portion 8. FIG. 3C is a plan view of the annular convex portion 10 shown in FIGS.

  Moreover, the cyclic | annular convex part 10 in this invention does not necessarily need to be cyclic | annular over the perimeter. As described above, a part of the air flowing in the axial direction by the rotation of the blade 6 is guided to the circuit board 9 side by the annular convex portion 10. However, in order to further enhance the cooling effect, it was subjected to cooling. It is preferable to expel air quickly to the outside. Therefore, a flat portion that enlarges the gap between the lower end portion of the blade 6 and the base portion 8 may be provided in a part of the annular convex portion 10. Thereby, a part of the air flowing in the axial direction can be guided to the circuit board 9 side, and the air used for cooling can be quickly discharged to the outside through the flat portion.

  In the present embodiment, as shown in FIGS. 1 and 2, the plurality of blades 6 are fixed apart from the outer peripheral surface of the rotor portion 2 via the connecting portion 5, but not limited thereto, As shown in FIG. 4, it may be fixed to the outer peripheral surface of the impeller cup 5b. Also in this case, the radial inner peripheral surface 10 a of the annular convex portion 10 is positioned radially outward from the fixed end 5 a of the connecting portion 5 and the blade 6, thereby flowing in the axial direction by the rotation of the blade 6. Part of the air can be guided to the circuit board 9 side.

  As mentioned above, although this invention was demonstrated by suitable embodiment, such description is not a limitation matter and of course various modifications are possible. For example, in the above embodiment, a ball bearing is used for the bearing portion 4 of the motor, but an oil-impregnated bearing made of a sleeve may be used.

2 Rotor part
3 Stator part
4 Bearing part
5 connecting parts
5a Fixed end
5b impeller cup
6 feathers
6a Stretched part
7 Bearing holding part
8 Base part
9 Circuit board
10 annular convex part
10a Radial inner surface
10b radially outer peripheral surface
11 Electronic parts 12 Reinforcing ring 21 Rotor holder
22 Field magnets
23 Shaft
100 Centrifugal fan

Claims (3)

A substantially cylindrical rotor portion that rotates about a rotation axis;
An annular connecting portion fixed to the rotor portion and extending radially outward of the rotor portion;
A plurality of blades fixed to the connecting portion and arranged in the circumferential direction of the rotor portion on the outer side in the radial direction of the rotor portion;
A bearing portion that rotatably supports the rotor portion;
A bearing holding portion for holding the bearing portion;
A substantially disc-shaped base portion to which the bearing holding portion is fixed;
A stator portion disposed on an inner peripheral side of the rotor portion and fixed to the bearing holding portion;
A circuit board disposed between the base portion and the stator portion,
The base part side end of the blade includes an extending part extending radially outward in the base part side,
The base portion includes a substantially annular convex portion that protrudes toward the base portion side end portion of the blade, on a radially outer side of the rotor portion,
A radially inner circumferential surface of the annular convex portion is located radially inward of the extending portion of the blade and radially outward of a fixed end of the connecting portion and the blade. fan. The centrifugal fan according to claim 1,
A centrifugal fan in which a radially inner circumferential surface of the annular convex portion is inclined toward a radially inner upper surface of the base portion. The centrifugal fan according to claim 1,
The centrifugal fan, wherein a radially outer peripheral end of the circuit board is located near a radially inner peripheral surface of the annular convex portion.

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