JP4577397B2 - Centrifugal fan device and electronic device including the same - Google Patents

Description

  The present invention relates to a centrifugal fan device used for cooling a heating element such as an ultra-compact processing unit (hereinafter referred to as MPU) mounted inside a housing of an electronic device, from a heat receiving member thermally connected to the heating element. The present invention relates to a centrifugal fan device that forcibly blows and cools a heat dissipating member after efficiently transporting heat to the heat dissipating member by a system such as a heat pipe or a circulation of a liquid refrigerant, and an electronic device including the centrifugal fan device.

  Recently, the speed of data processing in computers has been very rapid, and the clock frequency of MPU has become much higher than before.

  As a result, the amount of heat generated by the MPU is increased, and not only the conventional method of dissipating heat by contacting a heat sink having a radiating fin with the heat generator, but also the method of cooling the heat sink directly with a fan, or the heat generator and heat A heat sink module that transports heat from a connected heat receiving body to a heat sink using a heat pipe is configured, and the heat sink is forcibly cooled by blowing air from a fan, and a liquid refrigerant with high thermal conductivity is pumped. For example, a method for forcibly blowing and radiating heat from a heat radiating body that is forcibly circulated by the centrifugal fan device and is thermally transported between the heat receiving body and the heat radiating body is indispensable.

  On the other hand, the improvement of the cooling performance of the centrifugal fan device described above largely depends on the improvement of the air blowing performance such as high air volume and high static pressure, and the air blowing performance of the centrifugal fan device usually increases the rotation speed of the centrifugal fan. However, since the wind noise (hereinafter referred to as fan noise) of the blade portion of the centrifugal fan tends to increase, various blade portions of the centrifugal fan portion are reduced in order to reduce the fan noise. Shapes and orifice shapes have been proposed.

  Generally, such fan noise is classified into discrete frequency noise and broadband random noise. In particular, the discrete frequency noise is a blade part in which air on the rotating surface (positive pressure surface and negative pressure surface) of the blade plate rotates. This is due to air pressure fluctuations that occur each time (also referred to as a blade).

  In other words, since discrete frequency noise is generated in synchronization with the passage of the blade portion, it is harmonic noise having a fundamental frequency that is the product of the number of blade portions and the number of rotations of the fan. Therefore, it is also known that reducing discrete frequency noise is effective in reducing fan noise.

Here, as a conventional method for reducing discrete frequency noise, there has been a method in which a sawtooth-like uneven portion is provided at the tip of the blade portion (see, for example, Patent Document 1).
JP 2004-35396 A

  However, in the case where the sawtooth-shaped uneven portion is provided at the tip of the blade portion as described above, the eddy current that causes the discrete frequency noise generated at the tip of the fan is shunted by the sawtooth-shaped uneven portion and is reduced. However, since the centrifugal fan device is thin, the interval between the sawtooth-shaped uneven portions provided at the tip of the blade portion is narrow, and the interval between the adjacent vortex flows cannot be sufficiently ensured. As a result, even if the eddy current is divided by the sawtooth-shaped irregularities, the divided eddy currents are combined immediately after being divided and returned to the original eddy current, that is, the eddy current before the divided current, and noise can be reduced. There wasn't.

  Accordingly, in view of the above problems, the present invention is a centrifugal fan device capable of reducing the noise by reducing the vortex generated at the tip of the blade portion while diverting and reducing the vortex, and reducing the noise. The purpose is to provide equipment.

In order to achieve the above object, the present invention provides a centrifugal fan that has a plurality of blades and blows air in the centrifugal direction by rotation of the blades, and houses the centrifugal fan and is positioned on the outer side of the centrifugal fan. A centrifugal fan device having an inner wall surface and a casing having an air outlet that blows out air flowing along the inner wall surface, wherein the blade has an upper end surface shorter than a lower end surface. The distance between the tip portion of the first blade portion on the upper surface side of the blade and the hub portion is shorter than the distance between the tip portion of the second blade portion on the lower surface portion side of the blade and the hub portion. An annular plate is provided on the upper end surface of the second blade portion at a portion where the second blade portion protrudes toward the tip end side of the tip end portion of the first blade portion, and the first blade Upper part Part of the lower end surface of the part and the second blade portion of the surface is characterized by facing the casing.

  According to the present invention, it is possible to diminish the vortex generated at the tip of the blade portion by diverting it, while preventing the vortex from being separated from being coupled and reducing noise.

According to the first aspect of the present invention, the centrifugal fan includes a centrifugal fan having a hub portion and a blade extending from the hub portion, and a casing for housing the centrifugal fan, wherein the upper end surface of the blade is shorter than the lower end surface. Thus, the distance between the tip portion of the first blade portion on the upper surface portion side of the blade and the hub portion is the distance between the tip portion of the second blade portion on the lower surface portion side of the blade and the hub portion. And an annular plate is provided on the upper end surface of the second blade portion at a portion where the second blade portion protrudes more toward the tip than the tip of the first blade. A part of the upper end face of the first blade part and a part of the lower end face of the second blade part are opposed to the casing, thereby diverting the vortex generated at the tip of the blade part. While making it smaller Prevents binding of vortex can be reduced noise.

According to the invention described in claim 2, by providing the electronic device with the centrifugal fan device according to claim 1, noise caused by the centrifugal fan device in the electronic device can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing, the cover side is described as the upper side and the frame side as the lower side.

  1A and 1B are schematic views of a centrifugal fan device according to an embodiment of the present invention. FIG. 1A is a perspective view from above, and FIG. 1B is a perspective view from below.

  First, as shown in FIG. 1A, the fan casing 12 of the centrifugal fan device 11 is composed of a frame 12a located at the lower part and a cover 12b located at the upper part.

  Here, in the frame 12a, the side wall 12aa and the bottom wall 12ab are integrally formed by resin molding, die casting of aluminum alloy, press molding, or the like, and the air sucked into the fan casing 12 in the two directions to the outside. An exhaust port 13 for exhausting air is disposed, and a substantially circular air intake port 14a through which air sucked from the surroundings passes is disposed on the bottom wall 12ab (see FIG. 1B).

  On the other hand, the cover 12b is formed into a plate shape by stamping or resin molding of a metal material such as steel, aluminum, or copper, and a substantially circular intake port 14b through which air sucked in from the periphery is passed in the center. It is arranged.

  Since the fan casing 12 rotatably accommodates the centrifugal fan 15 that is driven to rotate, the pair of air inlets 14 a and air inlets 14 b are opposed to each other with the centrifugal fan 15 interposed therebetween.

  Here, the material of the centrifugal fan 15 is formed by integral molding using a resin material such as polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), or polyethylene terephthalate (PET).

  With the configuration as described above, the air sucked from both the air inlet 14a and the air inlet 14b is opposite to each other in the direction of the rotary shaft 18 fixed at the inner center of the hub portion of the centrifugal fan 15 (collision). Inhalation).

  FIG. 2 is a schematic view of a centrifugal fan in an embodiment of the present invention. As shown in FIG. 2, the centrifugal fan 15 includes a hub portion 21, a blade portion 22 extending from the hub portion 21, and two rings, an upper annular plate 23 and a lower annular plate 24. Rotate in the counterclockwise R direction.

  Here, the blade portion 22 has a step formed by a first blade portion 25 and a second blade portion 26 having different distances from the hub portion 21.

  In this embodiment, the first blade portion 25 and the second blade portion 26 have a long distance from the hub portion 21 and the length of the blade is long. It is preferable that the blade is longer, that is, the intake port of the first blade portion 25 is larger.

  At this time, it is desirable that the tip of the blade portion 22 overlaps the intake port so as to be hidden when viewed from the intake port, depending on the ratio of the lengths of the first blade portion 25 and the second blade portion 26. Therefore, it is preferable to change the intake port.

  The upper annular plate 23 is provided on the second blade portion 26 side, which is the upper surface of the blade portion 22, and the lower annular plate 24 is connected to the first blade portion 25 and the second blade portion 22 at the tip of the blade portion 22. It is provided between the blade portion 26 and has a larger diameter than the upper annular plate 23.

  This is because the lower annular plate 24 needs to be provided at the tip of the blade portion 22, and the upper annular plate 23 needs to be provided on the upper surface of the blade portion 22.

  In addition, it is easier to form the centrifugal fan 15 when the inner diameter of the lower annular plate 24 is equal to or larger than the outer diameter of the upper annular plate 23.

  Further, the upper annular plate 23 may be provided not on the second blade portion 26 side but on the first blade portion 25 side.

  FIG. 3 illustrates the shape of the tip of the blade portion. FIG. 3 is an enlarged view of the centrifugal fan device according to the present embodiment, where (a) is a top view of the centrifugal fan and (b) is a side view of the centrifugal fan.

  In FIG. 3, as described above, a step is formed by the first blade portion 25 and the second blade portion 26 at the tip of the blade portion 22, and the lower annular plate 24 is formed at the portion where the step changes. And an upper ring plate 23 is provided on the upper surface of the second blade portion 26.

  FIG. 4 shows an operation diagram of the centrifugal fan device. FIG. 4 is an operation diagram of the centrifugal fan device of this embodiment.

  In FIG. 4, the centrifugal fan rotates in the counterclockwise R direction. First, a vortex is shunted between the first blade portion 25 and the second blade portion 26 as indicated by a broken line, and thereafter As indicated by the solid line, the vortex flow divided by the first blade portion 25 and the second blade portion 26 is exhausted to the outside without being coupled by the lower annular plate 24.

  That is, the vortexes divided by the steps have different axes, preventing the combined vortexes from being easily combined, and further preventing the divided vortexes from being combined by the lower annular plate 24.

  As a result, the step provided on the blade part and the lower annular plate are used to divide the vortex with different axes, and the vortex separated by the lower annular plate is not coupled. The generated vortex can be reduced, the noise generated by this vortex can be reduced, and the noise of the centrifugal fan device can be reduced.

  It is desirable that the height in the rotation axis direction of the first blade portion 25 and the second blade portion 26, that is, the width of the blade is preferably the same width, and the eddy currents that are generated with the same width are equally divided to reduce noise. Since a large eddy current is not generated, it is preferable because noise is reduced as compared with a case where the width is different.

  In the present embodiment, the first and second blade portions having different lengths from the hub portion form a step, but a third blade portion having a different length may be provided, and the tip of the blade portion may be provided. May be formed in a step shape, and a lower annular plate may be provided in a portion where the length of the blade portion changes.

  The centrifugal fan device according to the present invention and the electronic apparatus including the centrifugal fan device can cool the MPU and various heat generating electronic components mounted inside the casing, and are required to be quieter notebook PC, PC server, sound Useful for equipment and video equipment.

Overview of centrifugal fan device in an embodiment of the present invention Overview of centrifugal fan in an embodiment of the present invention Enlarged view of centrifugal fan device in this embodiment Operational diagram of centrifugal fan device of this embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Centrifugal fan apparatus 12 Fan casing 12a Frame 12b Cover 12aa Side wall 12ab Bottom wall 13 Exhaust port 14a Inlet port 14b Inlet port 15 Centrifugal fan 21 Hub part 22 Blade part 23 Upper ring plate 24 Lower ring plate 25 First blade Part 26 Second blade part

Claims (2)

A centrifugal fan having a hub portion and a blade extending from the hub portion;
A casing that houses the centrifugal fan,
By making the upper end surface of the blade shorter than the lower end surface, the distance between the tip of the first blade portion on the upper surface portion side of the blade and the hub portion is the second distance on the lower surface portion side of the blade. Formed to be shorter than the distance between the tip of the blade part and the hub part,
An annular plate is provided on the upper end surface of the second blade portion of the portion where the second blade portion protrudes more toward the tip than the tip of the first blade,
A part of the upper end face of the first blade part and a part of the lower end face of the second blade part are opposed to the casing. An electronic apparatus comprising the centrifugal fan device according to claim 1.

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