JP5353864B2 - Blower - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blower which effectively reduces noise generated by wind propagated by blades, while preventing vicinities of surfaces of the blades from becoming a vacuum state and changes the frequencies and waveforms of the noise in multiple kinds. <P>SOLUTION: The blower includes a hub part having a cylindrical outer circumferential surface, a plurality of blades 22 supported on the hub part, a drive part driving the plurality of blades 22, and inside protrusions 28a and outside protrusions 28b protruding on the rotational-direction rear faces of the plurality of blades. The plurality of blades 22 include first blades having the hub part and the protrusions distant from each other by a first distance, and second blades having the hub part and the protrusions distant from each other by a second distance different from the first distance. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention is used for cooling a heating element such as an ultra-compact arithmetic processing unit (hereinafter referred to as MPU) mounted inside a casing of an electronic device, and is a blower having a structure for sucking air from both directions of a blow-in fan. It is about.

  Recently, the speed of data processing in computers has been very rapid, and the clock frequency of MPU has become much higher than before. Accordingly, an improvement in the cooling effect is required for the cooling device that cools the MPU, and an improvement in the air volume of the blower that constitutes the cooling device is required. However, if the air volume is increased, the noise will increase accordingly.

  In addition, as shown in, for example, (Patent Document 1), a conventional blower includes a blade that is curved outward from a hub portion in order to more efficiently propel wind.

JP 2007-138824 A

  However, especially in the above-described air blower, when the wind goes from the hub portion side of the blade to the outside, the wind tends to be peeled off from the blade. As a result, the vicinity of the surface of the blade is in a vacuum state on the outer peripheral end side of the blade, so that the amplitude of the wind noise is increased and the noise is increased. In addition, the above problem occurs even in a blade that is not curved.

  Therefore, the present invention is a blower that has been made in view of the above problems, prevents the vicinity of the surface of the blade from being in a vacuum state, and further varies the frequency and waveform of noise caused by the wind propelled by the blade. Therefore, it aims at suppressing noise effectively.

The present invention has been made in order to achieve the above object, and has a hub portion having a cylindrical outer peripheral surface, a plurality of blades supported by the hub portion, and a drive for driving the plurality of blades. And a protrusion provided on a rear surface in the rotation direction of the plurality of blades, the protrusion changes a wind passing over the protrusion in a vortex shape, and the plurality of blades are separated from the hub portion. a first blade distance between said protrusions is a first distance, and a second blade above the hub portion a distance is the first distance between the projections is different from the second distance It is an air blower characterized by comprising.

  According to the present invention, it is possible to prevent the vicinity of the surface of the blade from being in a vacuum state, and to further suppress noise effectively by differentiating the frequency and waveform of noise caused by the wind propelled by the blade into a plurality of types. it can.

Overview of centrifugal fan device in an embodiment of the present invention The perspective view of the centrifugal fan in the Example of this invention Overview of centrifugal fan in an embodiment of the present invention Diagram showing the flow of wind from the inlet to the outlet The enlarged view of the blade in the Example of this invention Diagram showing the relationship between noise and blade rotation frequency

According to the first aspect of the present invention, a hub portion having a cylindrical outer peripheral surface, a plurality of blades supported by the hub portion, a drive unit that drives the plurality of blades, and rotation of the plurality of blades A projection provided on a rear surface in the direction, wherein the projection changes a wind passing through the surface in a spiral shape, and the plurality of blades have a first distance from the hub portion to the projection . And a second blade whose second distance is different from the first distance from the hub portion to the projection. Thus, the vicinity of the blade surface can be prevented from being in a vacuum state, and the noise can be effectively suppressed by making the frequency and waveform of noise caused by the wind propelled by the blade different.

  According to the invention described in claim 2, the blower device according to claim 1, wherein the first blades and the second blades are alternately arranged. Since the projections of the blades adjacent to each other do not interfere with each other, it is easy to manufacture. Furthermore, since the shape of the vortex of the wind propelled by the adjacent blades is different and the frequency and waveform of the sound of the noise are different, noise can be suppressed more efficiently.

According to a third aspect of the present invention, the protrusion extends in the axial direction of the hub portion from one end portion of the blade to the other opposite end portion. The air blower of the blade reliably prevents the vicinity of the surface of the blade from becoming a vacuum state, and further makes noise more effective by differentiating the frequency and waveform of the noise caused by the wind propelled by the blade. Can be suppressed.

According to the fourth aspect of the present invention, according to claim 1, characterized in that said first projection formed on the blade with the projection formed on the second blade is the same size It is an air blower and is easy to manufacture.

According to the invention described in claim 5, the blower device according to claim 1, wherein the protrusion formed on the first blade is larger than the protrusion formed on the second blade. For example, in the case of a protrusion provided so as to be further away from the hub portion, separation from the blade may start before the wind reaches the protrusion , and there is a slight separation by forming the protrusion large. Even if it changes into a vortex, the wind can be reattached to the blade.

  Embodiments of the present invention will be described below with reference to the drawings. A centrifugal fan device will be described as an example of the blower device. In each drawing, the fan cover side is described as the upper side, and the fan frame side is described as the lower side.

  FIG. 1 is a schematic view of a centrifugal fan device according to an embodiment of the present invention. FIG. 2 is a perspective view of the centrifugal fan in the embodiment of the present invention.

  The centrifugal fan device 11 in this embodiment includes a central annular plate 24 extending in the centrifugal direction from the outer peripheral surface of the hub portion 21 having a cylindrical outer peripheral surface, a blade 22 supported by the central annular plate 24, and the blade 22. And a fan casing 12 that supports the drive unit and has intake ports 14a and 14b on the upper and lower surfaces, respectively, and the blade 22 has an inclined part 25 extending from the central annular plate 24, a fan A horizontal portion 26 substantially parallel to the upper and lower surfaces of the casing 12 is provided, and a ring 23 is provided on the horizontal portion 26. Preferably, the end portions of the intake ports 14a and 14b, the boundary 27 between the inclined portion 25 and the horizontal portion 26, and the outer end portion of the central annular plate 24 are in a direction parallel to the axis of the hub portion 21. Located on a straight line, the ring 23 is arranged at a position away from the boundary 27 between the inclined portion 25 and the horizontal portion 26 by a certain distance.

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

  Here, in the fan 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. An exhaust port 13 for exhausting the air sucked into the fan casing 12 to the outside is disposed in the two directions, and a substantially circular intake port 14a for allowing the air sucked from the surroundings to pass through is disposed on the bottom wall 12ab. (See FIG. 1).

  On the other hand, the fan 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 from the periphery passes through the central portion. 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 14 b are disposed to face 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 described above, the winds sucked from both the air inlet 14a and the air inlet 14b are opposite to each other in the direction of the rotation axis fixed to the inner center of the hub portion of the centrifugal fan 15 (they collide with each other). Direction).

  FIG. 3 is a schematic view of a centrifugal fan in an embodiment of the present invention. As shown in FIGS. 2 and 3, the centrifugal fan 15 includes a hub portion 21, a central annular plate 24 extending in the centrifugal direction from the outer peripheral surface of the hub portion 21, a blade 22 supported by the central annular plate 24, The centrifugal fan 15 is provided with a ring 23 formed on the blade, and rotates in the R direction counterclockwise in FIG. In the present embodiment, the hub portion 21, the blade 22, the ring 23, and the central annular plate 24 are formed by integral molding, but may be formed separately.

  The ring 23 is provided on one of the end faces of the blade with respect to the axial direction of the centrifugal fan 15, and is preferably provided on the end face on the fan cover 12b side. The ring 23 may be connected to all the blades 22 or may be connected to a part thereof. Preferably, the outer peripheral end of the ring 23 is aligned with the outer peripheral end of the blade 22. The central annular plate 24 extends outward from the hub portion 21 and is positioned substantially at the center of the blade 22 in the axial direction of the centrifugal fan 15. In addition, as long as it is not biased so that it may approach one upper-lower end surface of the braid | blade 22 in the axial direction of the centrifugal fan 15, you may position anywhere.

  The blade 22 may extend outward from the hub portion 21 or may extend outward from the central annular plate 24 in a state separated from the hub portion 21 as shown in FIG. Since both the fan frame 12a and the fan cover 12b are provided with the intake ports 14a and 14b, a space for intake is required at the position where the intake holes 14a and 14b are provided. Therefore, the portion of the blade 22 where the intake ports 14a and 14b are provided is short on both the upper and lower surfaces, and forms an inclined portion 25. Further, portions of the blade 22 that are covered by the fan frame 12 a and the fan cover 12 b are tall and form a horizontal portion 26 that is substantially parallel to the upper and lower surfaces of the fan casing 12. Accordingly, the blade 22 is short on the hub portion 21 side and gradually increases toward the outside, and is highest at the ends of the intake ports 14a and 14b, and is covered with the fan frame 12a and the fan cover 12b. The height is maintained at the part where it is.

  As described above, the cooling device of this embodiment includes the central annular plate 24 extending in the centrifugal direction from the outer peripheral surface of the hub portion 21 having the cylindrical outer peripheral surface, the blade 22 supported by the central annular plate 24, A drive unit such as a motor for driving the blade 22, and a fan casing 12 that supports the drive unit and has intake ports 14 a and 14 b on the upper and lower surfaces, respectively, and the blade 22 has an inclined portion 25 that extends from the central annular plate 24. The fan casing 12 includes a horizontal portion 26 substantially parallel to the upper and lower surfaces, and a ring 23 is provided on the horizontal portion 26. As a result, the air that has been sufficiently sucked in from both sides is rectified so that it can be efficiently exhausted from the exhaust port by a simple shape, improving the air blowing effect, and at the same time, preventing wind collision and bias and reducing noise. can do.

  Next, the flow of wind flowing through the fan casing 12 will be described. FIG. 4 is a diagram showing the flow of wind from the intake port to the exhaust port. FIG. 4 (a) shows the centrifugal fan of this embodiment described above, and FIG. 4 (b) shows the centrifugal flow of this embodiment. When the ring is removed from the fan, FIG. 4C shows the case where the central annular plate is removed from the centrifugal fan of this embodiment. FIG. 5 is an enlarged view of the blade in the embodiment of the present invention.

  As is clear from FIG. 4, the end portions of the intake ports 14 a and 14 b, the boundary 27 between the inclined portion 25 and the horizontal portion 26, and the outer end portion of the central annular plate 24 are parallel to the axis of the hub portion 21. Located in a straight line in the direction. The ring 23 is arranged at a position away from the boundary between the inclined portion 25 and the horizontal portion 26 by a certain distance. For example, in the case of the present embodiment, when the diameter of the centrifugal fan 15 is 48 mm, the diameter of the intake ports 14a and 14b is 36 mm. In the intake ports 14a and 14b having a diameter of 36 mm, a boundary 27 between the inclined portion 25 and the horizontal portion 26 and an outer end portion of the central annular plate 24 are aligned. That is, the outer peripheral end side 12 mm of the blade is the horizontal portion 26, and the inner side is the inclined portion 25. Further, when the diameter of the centrifugal fan 15 is 52 mm, the diameter of the intake ports 14a and 14b is 39 mm, and when the diameter of the centrifugal fan 15 is 43 mm, the diameter of the intake ports 14a and 14b is 32 mm. That is, when the axis of the centrifugal fan 15 is 0 and the outer peripheral end of the blade 22 is 100, about 75 to 100 of the blade is the horizontal portion 26 and the inside is the inclined portion 25. The start of the horizontal part 26 is good to be 70-80. If the intake ports 14a and 14b become larger than this, the propulsive force of the wind is reduced, and the sucked wind cannot be sufficiently scraped to the exhaust port, so that the air blowing effect is reduced. In addition, if the intake ports 14a and 14b are smaller than this, the air path becomes small and a sufficient amount of wind cannot be sucked, and the air blowing effect is reduced.

  By such a positional relationship, it is possible to rectify the wind sucked from both surfaces so that the air is efficiently exhausted from the exhaust port 13. That is, the wind sucked from the air inlet 14b on the fan cover 12b side changes the traveling direction in the centrifugal direction in the vicinity of the central annular plate 24. At this time, since it passes between the central annular plate 24 and the ring 23 and travels toward the exhaust port 13, the air flows near the middle of the central annular plate 24 and the ring 23 in the axial direction of the centrifugal fan 15 in the vicinity of the exhaust port 13. Makes it easier to concentrate. Further, the wind sucked from the air inlet 14a on the fan frame 12a side changes the traveling direction in the centrifugal direction in the vicinity of the central annular plate 24. At this time, it passes between the central annular plate 24 and the fan frame 12 a and goes to the exhaust port 13. And it becomes easy to concentrate a wind between the braid | blade 22 lower end and the fan frame 12a. Therefore, the wind tends to concentrate near the fan frame 12a in the vicinity of the exhaust port 13. In the case of the present embodiment, the wind that has reached the exhaust port 13 hits the fins 29 and is exhausted. As a result, the air sucked from the air inlet 14b on the fan cover 12b side is concentrated near the middle of the central annular plate 24 and the ring 23 in the axial direction of the centrifugal fan 15 in the vicinity of the air outlet 13, and the fan frame 12a. The wind sucked from the side air inlet 14b is concentrated in the vicinity of the fan frame 12a, and thus is dispersed.

  As a result, the airflow in the axial direction of the centrifugal fan 15 can be rectified so as to disperse the airflow in the vicinity of the exhaust port 13 in a balanced manner, so that the airflow can be increased and the cooling effect can be improved in the same noise situation. it can. Moreover, the rectification can prevent wind collision and bias, and can suppress noise. Further, when the fins 29 are provided as the cooling device, the wind is uniformly applied to the fins 29, and the cooling effect can be improved. Further, it is possible to suppress collision between winds sucked from the opposite direction, increase the air volume, and improve the cooling effect.

  In addition, the presence of the ring 23 allows the wind propelled from one blade to pass around between the blade 22 and the fan casing 12 and move around the other blades in the front and rear. Can be prevented. As a result, it is possible to prevent the formation of vortices due to the wrapping wind and to suppress noise.

  Next, the case where the ring 23 is removed from the centrifugal fan of this embodiment will be described with reference to FIG. In this case, the wind sucked from both the air inlets 114b on the fan frame 112a and the fan cover 112b side changes the traveling direction in the centrifugal direction in the vicinity of the central annular plate 124. At this time, it passes between the central annular plate 124 and the fan frame 112a and goes to the exhaust port 113. Then, the wind easily flows between the upper and lower ends of the blade 122 and the fan frame 112a and the fan cover 112b. Therefore, in the vicinity of the exhaust port 113, the wind tends to concentrate near the fan frame 112a and the fan cover 112b. In the meantime, when the wind is concentrated near both the fan frame 112a and the fan cover 112b, the wind is sneak between both the blade 122 and the fan frame 112a and the fan cover 112b, and noise is easily generated by the vortex. Furthermore, wind hits around the exhaust port 13 and the air blowing effect is reduced. Further, since there is not much wind on the center side in the vicinity of the exhaust port 113, the balance is poor, and the wind is not well dispersed. In the case of the present embodiment, the heat exchange efficiency of the fins 129 is deteriorated.

  Next, the case where the central annular plate 24 is removed from the centrifugal fan of this embodiment will be described with reference to FIG. Since the air sucked from both the air inlets 214a and 214b on the fan frame 212a and fan cover 212b side comes toward the axial center of the centrifugal fan 215, they collide with each other near the center. The air volume will decrease. Further, the wind colliding near the center changes direction in the centrifugal direction, but goes toward the exhaust port 213 while being concentrated near the axial center of the centrifugal fan 215. Therefore, the wind cannot be dispersed near the exhaust port 213. As a result, the heat exchange rate of the fins 229 is deteriorated.

  The ring 23 may be formed on both the upper and lower surfaces of the horizontal portion of the blade, but if it is at least on one side, the wind can be sufficiently dispersed in the axial direction of the centrifugal fan 15, improving the blowing effect. Noise can be reduced.

  Even if there is no fin 29, the air blowing effect is improved by the rectifying effect and the effect of reducing the noise can be obtained. However, when the fin 29 is present, the entire fin 29 can be blown uniformly. Therefore, the improvement of the cooling effect becomes remarkable.

  As described above, in the double-sided intake type blower, both the central annular plate 24 and the ring 23 are required to rectify the air sucked from both sides so as to be efficiently exhausted from the exhaust port 13. Become.

  Further, the end portions of the intake ports 14a and 14b, the boundary 27 between the inclined portion 25 and the horizontal portion 26, and the outer end portion of the central annular plate 24 are aligned in a direction parallel to the axis of the hub portion 21. As a result, the following effects can be obtained. That is, when the boundary 27 between the inclined portion 25 and the horizontal portion 26 is located inside the ends of the intake ports 14a and 14b, the horizontal portion 26 interferes with intake. Therefore, the air volume sucked from the intake ports 14a and 14b is reduced, and the cooling effect is reduced. Further, when the boundary 27 between the inclined portion 25 and the horizontal portion 26 is positioned outside the end portions of the intake ports 14a and 14b, the horizontal portion 26 becomes small, and the propulsive force of the wind as the blade 22 is reduced. I will let you. As a result, the air volume is reduced and the cooling effect is reduced. The horizontal portion 26 needs to be as large as possible.

  Further, when the outer end portion of the central annular plate 24 is located on the inner side than the end portions of the intake ports 14a and 14b, a part of the sucked air is sucked into both the fan frame 12a and the fan cover 12b side. The winds sucked from the mouth 14b collide with each other near the center, and the air volume decreases. Further, when the outer end portion of the central annular plate 24 is positioned outside the end portions of the intake ports 14a and 14b, when considering the horizontal portion 26 of the blade 22, the central annular plate 24 extends to the horizontal portion 26. Is divided into upper and lower parts, and two small blades are connected. The propulsive force of the blade 22 can increase the air blowing effect with one larger blade than two small blades. Therefore, it is preferable that the central annular plate 24 is as small as possible.

  Therefore, the end portions of the intake ports 14a and 14b, the boundary 27 between the inclined portion 25 and the horizontal portion 26, and the outer end portion of the central annular plate 24 are aligned in a direction parallel to the axis of the hub portion 21. By being, it can improve a ventilation effect most efficiently.

  In addition, the ring 23 is disposed at a position away from the boundary between the inclined portion 25 and the horizontal portion 26 by a certain distance, in this embodiment, 1 mm. The fixed distance is preferably about 0.5 to 2 mm, but may be 2 mm or more according to the size of the centrifugal fan device 11.

  With such a configuration, the amount of air that can be taken in can be increased. That is, the wind sucked from the intake port 14a can gradually spread in the centrifugal direction. However, if the ring 23 extends to the inside of the end of the intake port 14a, the intake will be disturbed. Further, when the ring 23 extends to the end of the intake port 14a, the sucked wind can only travel in a direction parallel to the axial direction of the centrifugal fan 15 until it passes through the ring 23. Can change direction. Accordingly, the amount of air that can be taken in decreases.

  Further, when the wind near the exhaust port 13 passes between the ring 23 and the fan cover 12b and returns to the center side, the ring 23 ends in front of the intake port 12a. It is possible to switch and head again in the centrifugal direction.

  Next, the shape of the horizontal portion 26 of the blade 22 will be described. FIG. 6 is a diagram showing the relationship between noise and blade rotation frequency.

  The centrifugal fan device 11 of the present invention includes a hub portion 21 having a cylindrical outer peripheral surface, a plurality of blades 22 supported by the hub portion 21, a drive unit that drives the plurality of blades 22, and a plurality of blades 22. A plurality of blades 22 are provided with inner protrusions 28a and outer protrusions 28b that are convex portions provided on the rear surface in the rotation direction, and the plurality of blades 22 are first distances between the convex portions from the hub portion 21. And a second blade whose distance from the hub portion to the convex portion is a second distance different from the first distance. In addition, the back surface in the rotation direction of the blade 22 refers to a backward direction surface and a low pressure surface, and refers to a back surface with respect to a surface on which wind strikes.

  That is, as apparent from FIG. 5, each blade 22 includes an inner protrusion 28 a that is a convex portion or an outer protrusion 28 b that is a convex portion on the rear side surface in the rotation direction R. The inner protrusions 28a and the outer protrusions 28b are provided alternately, and the protrusions provided on the adjacent blades 22 are always configured to be misaligned as the inner protrusions 28a and the outer protrusions 28b.

  In the case of the present embodiment, the inner protrusion 28a and the outer protrusion 28b have a substantially radial shape with a width of 0.6 to 1.2 mm. The thickness of the horizontal portion 26 of the blade 22 is 0.45 mm to 0.7 mm.

  Further, when the axis of the centrifugal fan 15 is 0 and the outer peripheral end of the blade 22 is 100, the inner protrusion 28a is at positions 80 to 89, the outer protrusion 28b is at positions 85 to 95, and the inner protrusion 28a and the outer protrusion 28b are The distance is 4-15. For example, if the radius of the centrifugal fan 15 is 24 mm, the inner protrusion is at a position 20.6 mm from the axis of the centrifugal fan 15, the outer protrusion is at a position 22.1 mm from the axis of the centrifugal fan 15, and the inner protrusion 28 a is 86 The position and outer protrusion 28b are arranged at the position 92. If the radius of the centrifugal fan 15 is 26 mm, the inner protrusion is at a position 22.6 mm from the axis of the centrifugal fan 15, the outer protrusion is at a position 24.1 mm from the axis of the centrifugal fan 15, and the inner protrusion 28a is 87. If the radius of the centrifugal fan 15 is 21.5 mm, the inner projection is 18 mm from the axis of the centrifugal fan 15, and the outer projection is 19. The inner protrusion 28a is disposed at a position 84, and the outer protrusion 28b is disposed at a position 91. Of course, the arrangement is not limited to this.

  By arranging the inner protrusion 28a and the outer protrusion 28b in this way, noise caused by blowing can be reduced. That is, when the wind is directed outward from the center side of the blade 22, the wind is separated from the blade 22 if there is no protrusion, and the vicinity of the surface of the blade 22 is in a vacuum state on the outer peripheral end side of the blade 22. As a result, the sound amplitude is increased, resulting in loud noise. However, when the wind passes over the inner protrusion 28a or the outer protrusion 28b, the wind changes in a vortex shape, reattaches to the blade 22 and advances to the outer peripheral end. At this time, the blade 22 provided with the inner protrusion 28a and the blade 22 provided with the outer protrusion 28b among the blades 22 have different distances until the wind changes in a vortex shape and travels to the outer peripheral end. As a result, the shape of the vortex is different and the frequency and waveform of the noise are different. Therefore, as shown in FIG. 6B, the value in the vicinity of 2300 Hz indicating the peak value in FIG. 6A is considerably reduced. Therefore, the shape of the graph in FIG. 6B is flattened more clearly than in FIG.

  Further, by adopting such a shape, since the projections of the adjacent blades 22 do not interfere with each other when the blades 22 are molded, it is easy to manufacture. Furthermore, since the shape of the vortex of the wind propelled by the adjacent blades 22 is different and the frequency and waveform of the sound of the noise are different, noise can be suppressed more efficiently.

  Further, the outer peripheral end of the ring 23 may be arranged so as to be aligned linearly with the outer peripheral end of the blade 22. As a result, the sucked wind can be efficiently rectified to the position of the exhaust port 13, so that the air blowing effect can be improved, and at the same time, noise and noise can be reduced by preventing collision and bias between the winds.

  In this embodiment, the inner protrusion 28a and the outer protrusion 28b have the same size, but may be different. In particular, a larger effect can be obtained by making the outer protrusion 28b larger than the inner protrusion 28a. That is, in the case of the outer protrusion 28b, the peeling from the blade 22 may start before the wind reaches the outer protrusion 28b. Therefore, by forming the outer protrusion 28b large, even if there is some peeling, it is changed into a vortex, and the wind can be reattached to the blade 22.

  Further, the inner protrusion 28a and the outer protrusion 28b do not necessarily extend from one end of the blade 22 to the other opposite end in the axial direction of the hub portion 21, but by configuring in this way, In addition, it is possible to reliably prevent the vicinity of the surface of the blade 22 from being in a vacuum state, and further to suppress noise more effectively by differentiating the frequency and waveform of the noise caused by the wind propelled by the blade into a plurality of types. .

  Further, the protrusions need not be arranged at two places, the inner protrusion 28a and the outer protrusion 28b, but may be three or more places. In particular, it is preferable for the centrifugal fan 15 having a large diameter.

  Further, the shape of the centrifugal fan 15 is not limited to the shape of the present embodiment, and an effect of reducing noise can be obtained regardless of the shape. Particularly, it is useful that the end portion of the blade 22 is bent in the direction opposite to the rotation direction because the wind is easily peeled off.

  The blower according to the present invention is capable of cooling the MPU and various heat generating electronic components mounted inside the housing, and is useful for notebook PCs, PC servers, audio equipment, video equipment, and the like that are required to be quieter. is there.

DESCRIPTION OF SYMBOLS 11 Centrifugal fan apparatus 12 Fan casing 12a Fan frame 12b Fan cover 12aa Side wall 12ab Bottom wall 13 Exhaust port 14a Inlet port 14b Inlet port 15 Centrifugal fan 21 Hub part 22 Blade 23 Ring 24 Central ring plate 25 Inclined part 26 Horizontal part 27 Boundary 28a Inner protrusion 28b Outer protrusion 29 Fin

Claims (5)

A hub portion having a cylindrical outer peripheral surface;
A plurality of blades supported by the hub portion;
A drive unit for driving the plurality of blades;
A protrusion provided on a rear surface in the rotation direction of the plurality of blades,
The projection changes the wind passing over the projection into a vortex,
Wherein the plurality of blades, a first blade distance between said projection from said hub portion is a first distance, different from the second from the distance the distance of the first between the protrusion from the hub portion And a second blade having a distance of. The air blower according to claim 1, wherein the first blade and the second blade are alternately arranged. 2. The blower according to claim 1, wherein the protrusion extends from one end of the blade to the other opposite end in the axial direction of the hub portion. Blower according to claim 1, characterized in that the projection formed on the second blade and the protrusions formed on the first blade is the same size. The blower according to claim 1, wherein the protrusion formed on the first blade is larger than the protrusion formed on the second blade.

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