JP2009250158A - Bower fan - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily assemble a cup and a rotor holder of a blower fan. <P>SOLUTION: The rotor holder 221 of a motor is press-fit into the cup of an impeller of the blower fan. The cup has four projections which project downward from the bottom surface of the top at equal intervals in the circumferential direction and the rotor holder 221 of a rotor has eight fixed holes 2214 at a cover 2212 at regular intervals in the circumferential direction. When the impeller and the rotor section are assembled the projections of the cup section are inserted into the fixed holes 2214 and tips are fused so that the rotor holder 221 and the impeller are fixed. The fixed holes 2214 are elongated in the circumferential direction by which the cup and the rotor holder 221 can be easily assembled without adjusting positions of the impeller and the rotor section properly. Misalignment can be corrected flexibly by forming the many fixed holes 2214 in the circumferential direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a blower fan, which is preferably used for cooling an electronic device.

  As electronic devices become more sophisticated, the amount of heat generated in the electronic components inside the housing of the electronic devices continues to increase, and cooling fans are used to suppress the temperature rise of the electronic components. . In order to suppress the temperature rise inside the electronic device by the blower fan, it is necessary to increase the rotational speed of the blower fan to improve the static pressure-air volume characteristic of the blower fan. On the other hand, as the rotational speed increases, vibration due to the effect of imbalance on the rotating shaft of the rotating body of the blower fan (impeller and motor rotor) increases, and therefore it is important to reduce the rotational unbalance of the rotating body.

  Conventionally, a rotating body of a small blower fan employs a fastening method in which a rotor holder is press-fitted into an impeller. However, in a large blower fan or the like, when the impeller and the rotor holder are fastened only by press-fitting, the impeller is damaged or disconnected. The problem is concerned. Therefore, a method is adopted in which a through hole is provided in the rotor holder, a protrusion is provided in the impeller, a protrusion is inserted into the through hole, and the tip of the protrusion is heated and crushed to fasten the impeller and the rotor holder.

  For example, in the brushless DC motor disclosed in Patent Document 1 and the axial fan motor disclosed in Patent Document 2, the impeller is fixed to the rotor yoke by a heat caulking portion that protrudes downward in the impeller (impeller). In the sirocco fan motor disclosed in Patent Document 3, the cup-shaped hub portion of the impeller has a rib for ultrasonic welding, and the cup-shaped hub portion is press-fitted into a rotor frame having a top hole and inserted into the top hole. The ribs are welded to the rotor frame by the ultrasonic welding horn, and the impeller and the rotor frame are fixed.

In the blower disclosed in Patent Document 4, the cylindrical portion of the impeller has a latching body, and when the cylindrical motor yoke is fitted and fixed to the cylindrical portion of the impeller, the flexible portion is flexible. Work is facilitated by the engagement of the latching body.
Japanese Patent Laid-Open No. 1-198263 No. 7-13416 Japanese Patent Laid-Open No. 7-111756 JP 2002-39096 A

  By the way, in order to correct the unbalance of the rotor of the blower fan, the relative position in the circumferential direction is adjusted so that the unbalance of the rotor holder and the unbalance of the impeller are offset when the rotor holder and the impeller are combined. Although it is necessary to fasten, in the assembling methods disclosed in Patent Documents 1 to 4, the relative position can be adjusted only in a limited manner, and it is difficult to sufficiently correct the imbalance. Moreover, since accurate alignment is required when inserting the protrusion which the impeller has into the hole which the rotor holder has, the workability of the assembly work is low.

  The present invention has been made in view of the above problems, and has as its main object to facilitate the assembly of the cup portion and the rotor holder, and also to flexibly correct the unbalance.

  The invention according to claim 1 is a blower fan, a motor part having a covered substantially cylindrical rotor holder, and a covered substantially cylindrical cup that covers at least part of the outer surface and at least part of the upper surface of the rotor holder. And an impeller having a plurality of blades arranged in a ring shape and projecting radially outward from the cup portion, and an upper portion of the rotor holder is arranged in a circumferential direction centering on a central axis of the motor portion And each of the circumferential portions has a plurality of holes longer than a radial width around the central axis, and the upper portion of the cup portion protrudes from the lower surface toward the rotor holder, and It has a plurality of protrusions that are inserted into a plurality of holes and that fix the rotor holder to the cup by crushing the tip by melting.

  Invention of Claim 2 is a ventilation fan of Claim 1, Comprising: The length of the said circumferential direction of these hole parts is 2 times or more of the diameter of these protrusions.

  The invention according to claim 3 is the blower fan according to claim 1 or 2, wherein the number of the plurality of hole portions is larger than the number of the plurality of protrusions, and the plurality of hole portions include the plurality of holes. The number of orientations of the rotor holder with respect to the cup part into which the protrusion can be inserted is larger than the number of the plurality of protrusions.

  The invention according to claim 4 is the blower fan according to claim 3, wherein the plurality of holes and the plurality of protrusions are arranged at equal intervals in the circumferential direction, and the number of the plurality of holes is It is an integer multiple of 2 or more of the number of the plurality of protrusions.

  Invention of Claim 5 is an air blower fan in any one of Claim 1 thru | or 4, Comprising: At least 1 of the said circumferential direction length is the said circumference of another hole part among these several hole parts. By making it different from the length in the direction, the unbalance of rotation around the central axis in the rotor holder is reduced in advance.

  The invention according to claim 6 is a blower fan, a motor part having a covered substantially cylindrical rotor holder, and a covered substantially cylindrical cup that covers at least part of the outer surface and at least part of the upper surface of the rotor holder. And an impeller having a plurality of blades arranged in a ring shape and projecting radially outward from the cup portion, and an upper portion of the rotor holder is arranged in a circumferential direction centering on a central axis of the motor portion The upper part of the cup part protrudes from the lower surface toward the rotor holder and is inserted into the plurality of hole parts, and the tip is crushed by melting to fix the rotor holder to the cup part. A plurality of projections, wherein the number of the plurality of hole portions is greater than the number of the plurality of projections, and the cup portion into which the plurality of projections can be inserted into the plurality of hole portions. The number of orientation of the rotor holder that is greater than the number of said plurality of projections.

  The invention according to claim 7 is the blower fan according to claim 6, wherein the plurality of holes and the plurality of protrusions are arranged at equal intervals in the circumferential direction, and the number of the plurality of holes is It is an integer multiple of 2 or more of the number of the plurality of protrusions.

  The invention according to claim 8 is the blower fan according to any one of claims 1 to 7, wherein the tips of the plurality of protrusions are melted and crushed by thermal welding or ultrasonic welding.

  In the present invention, the cup portion and the rotor holder can be easily assembled. According to the second aspect of the invention, the balance of the rotating body can be finely adjusted, and in the third and sixth aspects of the invention, the balance of the rotating body can be corrected more flexibly. In the inventions of claims 4 and 7, the design of the rotor holder and the impeller can be facilitated.

  FIG. 1 is a longitudinal sectional view showing a blower fan 1 according to a first embodiment of the present invention. The blower fan 1 is used for air cooling of an electronic device. In the blower fan 1, air flows along the central axis J1 so that air is taken in from the upper side in FIG. 1 and sent out to the lower side. . In the following description, in the direction of the central axis J1, the upper side in FIG. 1 that is the side from which air is taken is called the “intake side” or simply “upper side”, and the lower side in FIG. Is called “exhaust side” or simply “lower side”. The expressions “upper” and “lower” do not necessarily coincide with the upper and lower sides with respect to the direction of gravity.

  The blower fan 1 includes a motor unit 2, an impeller 3 that generates an air flow by the rotation of the motor unit 2, a housing 4 that surrounds the outer periphery of the impeller 3, and a plurality of (four in this embodiment) that support the motor unit 2. Support ribs 5). In the blower fan 1, the impeller 3, the motor unit 2, and the support rib 5 are disposed inside the housing 4, and the support rib 5 extends from the outer periphery of the base unit 211 of the motor unit 2 toward the inner surface of the housing 4 and is The base part 211 and the housing 4 are connected in the direction.

  The impeller 3 protrudes radially outward from the outer surface of the cup portion 31 around the cup portion 31 with a substantially cylindrical shape that covers the outside of the motor portion 2 and the central axis J1 that is also the central axis of the motor portion 2. In addition, a plurality of (seven in this embodiment) blades 32 are arranged in a ring shape, and the cup portion 31 and the blades 32 are formed as one member by resin injection molding. In FIG. 1, for convenience of illustration, the schematic shapes of the blades 32 and the support ribs 5 of the impeller 3 are shown on the left and right of the central axis J1, and illustration of parallel oblique lines with respect to the cross-sections of the respective components is omitted as appropriate.

  The motor unit 2 includes a rotor unit 22 that is a rotating body and a stator unit 21 that is a fixed body, and the rotor unit 22 is positioned above the stator unit 21 along the central axis J1. The stator portion 21 includes a substantially disc-shaped base portion 211, a substantially cylindrical bearing holding portion 212 protruding upward from the center of the base portion 211, an armature 213 attached to the outer periphery of the bearing holding portion 212, and A circuit board 214 having a substantially annular plate shape attached to the lower side of the armature 213 is provided. The circuit board 214 is electrically connected to the armature 213 and connected to an external power source through a lead wire, and has a control circuit that controls the rotation of the rotor unit 22. Inside the bearing holding portion 212, ball bearings 215 and 216, which are bearing mechanisms, are provided at an upper portion and a lower portion in the direction of the central axis J1.

  FIG. 2 is a longitudinal sectional view showing an assembly of the rotor portion 22 and the impeller 3, and FIG. 3 is an exploded view of the rotor portion 22 and the impeller 3. As shown in FIG. 2, the rotor portion 22 has a substantially cylindrical shape with a lid centered on the central axis J <b> 1 and is a magnetic rotor holder 221 that is a magnetic body, and a substantially cylindrical field that is fixed inside the rotor holder 221. Magnet 222 and a shaft 223 having an upper end attached to the center of the upper portion of the rotor holder 221, and the rotor portion 22 is attached to the armature 213 by inserting the shaft 223 into the ball bearings 215 and 216 (see FIG. 1). And is rotatably supported. The rotor part 22 is an integral part of the impeller 3 when the outer surface and upper surface of the rotor holder 221 are covered with the cup part 31. As shown in FIG. 1, the field magnet 222 is opposed to the armature 213 of the stator portion 21 in the radial direction, and a drive current is supplied to the armature 213 from the external power source via the circuit board 214. Torque about the central axis J1 is generated between the field magnet 222 and the armature 213, and the rotor portion 22 and the impeller 3 rotate relative to the armature 213 about the central axis J1.

  FIG. 4 is a bottom view of the impeller 3. As shown in FIGS. 3 and 4, the cup portion 31 of the impeller 3 has a cylindrical side portion 311 and a lid portion 312 that closes the upper end of the side portion 311. The lid portion 312 that is the upper portion of the cup portion 31 has a substantially disc shape perpendicular to the central axis J1, and has a plurality of protrusions 3121 that protrude from the lower surface toward the rotor holder 221 (ie, downward). The protrusions 3121 are arranged at four positions at equal intervals in the circumferential direction, and are formed of resin as a part of the cup portion 31.

  FIG. 5 is a bottom view of the rotor holder 221. As shown in FIGS. 3 and 5, the rotor holder 221 has a cylindrical side portion 2211 and a lid portion 2212 that is an upper portion of the rotor holder 221, and the lid portion 2212 is perpendicular to the central axis J <b> 1 that substantially closes the upper end of the side portion 2211. It has a substantially disk shape. The lid 2212 has a hole 2213 to which the shaft 223 is attached at the center, and a plurality of fixing holes 2214 around the hole 2213. The fixing holes 2214 are arranged at eight equal intervals in the circumferential direction centered on the central axis J1 and are long in the circumferential direction (that is, the circumferential length is a radial width centered on the central axis J1). Longer). The length of each fixing hole 2214 in the circumferential direction (the arc-shaped distance to both ends in the circumferential direction at the center in the radial direction of each fixing hole 2214, which is denoted by a symbol L in FIG. 5) is the protrusion of the impeller 3 The diameter of the fixing hole 2214 (the distance in the radial direction, denoted by a symbol W in FIG. 5) is slightly larger than the diameter of the protrusion 3121 of the impeller 3.

  As shown in FIG. 3, when assembling the impeller 3 and the rotor part 22, the impeller 3 and the rotor part 22 have their respective central axes aligned, and the lower surface of the lid part 312 of the impeller 3 and the upper surface of the lid part 2212 of the rotor part 22. The rotor holder 221 is fixed to the cup portion 31 of the impeller 3 by light press-fitting while the projections 3121 of the impeller 3 are inserted into the fixing holes 2214 of the rotor holder 221 at the corresponding positions. At this time, since the fixing hole 2214 is a hole that is long in the circumferential direction, the insertion can be performed without strictly determining the position of the protrusion 3121 with respect to the fixing hole 2214, and the assembling work is facilitated. Further, after light press-fitting, as shown in FIG. 2, the tip of each projection 3121 is melted and crushed by heat welding, so that the rotor holder 221 is fixed to the cup portion 31. In addition to thermal welding, ultrasonic welding using melting by ultrasonic waves may be employed.

  As described above, in the blower fan 1 according to the first embodiment, the fixing hole 2214 is a long hole in the circumferential direction, so that the rotor holder 221 is set on a jig and the rotor holder 221 is impeller 3. When the cup part 31 is inserted, the protrusion 3121 of the cup part 31 can be inserted into the fixing hole 2214 of the rotor holder 221 without accurately matching the circumferential direction of the rotor holder 221 with respect to the cup part 31. And the rotor holder 221 can be easily assembled and the blower fan 1 can be efficiently assembled. In addition, since the radial width W of the fixing hole 2214 is substantially equal to the diameter of the protrusion 3121, when the tip of the protrusion 3121 is melted, the tip of the protrusion 3121 melted on both sides of the fixing hole 2214 in the radial direction. The part spreads and heat welding is performed reliably.

  By the way, in the assembly of the blower fan 1, in order to reduce the unbalance during rotation, the orientation of the impeller 3 relative to the rotor holder 221 is required in advance so that the unbalance of the rotor holder 221 and the unbalance of the impeller 3 are offset. The rotor holder 221 is lightly press-fitted into the cup portion 31 of the impeller 3 according to this direction during assembly. On the other hand, in the blower fan 1, the number of fixing holes 2214 is twice the number of the protrusions 3121, and the fixing holes 2214 and the protrusions are arranged at equal intervals in the circumferential direction, so that the protrusions 3121 are inserted into the fixing holes 2214. The number of circumferential orientations of the rotor holder 221 relative to the possible cup portion 31 is twice the number of protrusions 3121. In other words, the blower fan 1 is inserted into the cup portion 31 more than when the number of fixing holes 2214 is equal to the number of protrusions 3121 (that is, the number of orientations in which the rotor holder 221 can be inserted is equal to the number of protrusions 3121). The number of relative orientations of the rotor holder 221 that can be increased.

  As a result, the degree of freedom of the direction of the impeller 3 with respect to the rotor holder 221 can be improved, and the balance of rotation of the rotor portion 22 that is a rotating body can be corrected more flexibly. Further, in the rotor holder 221 of FIG. 5, since the circumferential length of the fixing hole 2214 is set to be twice or more the diameter of the protrusion 3121, the degree of freedom of the orientation of the impeller 3 with respect to the rotor holder 221 can be improved. The balance of the unit 22 can be finely adjusted.

  Since the number of fixing holes 2214 is an integral multiple of the number of protrusions 3121 and the fixing holes 2214 and the protrusions 3121 are arranged at equal intervals, the rotor holder 221 and the cup portion 31 are rotationally symmetric. The design of the impeller 3 can be facilitated.

  Further, by making the fixing hole 2214 a long hole, the circumferential length of at least one fixing hole 2214 is slightly different from the circumferential length of the other fixing holes 2214. The rotation imbalance around the central axis J1 in the rotor holder 221 may be reduced in advance (the same applies to FIGS. 6 and 8 described later). In this case, for example, the imbalance of the rotor holder 221 in which a plurality of fixing holes 2214 having the same circumferential length is formed in advance is measured, and the circumferential length of one of the fixing holes 2214 is corrected. Based on the above, the shape of the pin of the mold for forming the fixing hole 2214 is changed.

  FIG. 6 is a view showing another example of the rotor holder. The rotor holder 221a of FIG. 6 differs from the rotor holder 221 of FIG. 5 in that the circumferential length L of the fixing hole 2214a of the rotor holder 221a is about 1.2 times the width W, and the others are the same. Yes.

  Also in the rotor holder 221a shown in FIG. 6, the assembly operation can be facilitated by inserting the impeller 3 and the rotor holder 221 without strictly determining the position of the projection 3121 during the assembly operation. Further, the number of the fixing holes 2214a is an integral multiple of the number of the protrusions 3121, and the protrusions 3121 and the fixing holes 2214a are arranged at equal intervals in the circumferential direction, so that the rotation balance can be flexibly corrected. Furthermore, since the area of the fixing hole 2214a is small, the influence of the fixing hole 2214a on the strength of the lid portion 2212 can be suppressed.

  FIG. 7 is a bottom view showing the rotor holder 221b in the blower fan according to the second embodiment of the present invention. The rotor holder 221b has a circular fixing hole compared to the rotor holder 221 of FIG. It is. Other portions of the blower fan are the same as those in FIG. The fixing holes 2214b of the rotor holder 221b are arranged at eight equal intervals in the circumferential direction around the central axis J1, and have a slightly larger diameter than the four protrusions 3121 of the impeller 3 shown in FIG. When the impeller 3 and the rotor holder 221b are assembled, the projection 3121 is inserted only into the fixing hole 2214b corresponding to the projection 3121 and the tip of the projection 3121 is melted and crushed, as in FIGS. The rotor holder 221b is fixed to the impeller 3.

  Also in the rotor holder 221b of FIG. 7, the number of the fixing holes 2214b is twice the number of the protrusions 3121, and the fixing holes 2214b and the protrusions 3121 are arranged at equal intervals in the circumferential direction. The number of orientations of the rotor holder 221b relative to the cup portion 31 of the impeller 3 into which the 312 can be inserted is larger than the number of the protrusions 3121. As a result, it is possible to flexibly correct the rotation balance. Further, the arrangement of the fixing holes 2214 and the protrusions 3121 at equal intervals facilitates the design of the rotor holder 221b and the impeller 3.

  FIG. 8 is a bottom view showing a rotor holder 221c in a blower fan according to a third embodiment of the present invention. The rotor holder 221c has a different shape and number of fixing holes compared to the rotor holder 221 of FIG. It is. The fixing holes 2214c of the rotor holder 221c are further elongated in the circumferential direction as long as the strength of the lid portion 2212 is maintained as compared with the fixing holes 2214 of the rotor holder 221 in FIG. 5, and are provided at four locations in the circumferential direction around the central axis J1. Arranged at equal intervals. In the rotor holder 221c, the rotor holder 221c is fixed to the impeller 3 by being lightly press-fitted into the impeller 3 shown in FIG. 4 and inserting the protrusions 3121 into the fixing holes 2214c, and melting and crushing the tips of the protrusions 3121. .

  Also in the rotor holder 221c, the fixing hole 2214c is lengthened in the circumferential direction, so that the protrusion 3121 of the cup portion 31 can be formed on the rotor holder 221c without accurately matching the circumferential direction of the rotor holder 221c with respect to the cup portion 31 (see FIG. 4). It can be inserted into the fixing hole 2214c, and the cup portion 31 and the rotor holder 221c can be easily assembled. Further, since the fixing hole 2214c is a long long hole, the degree of freedom of the orientation of the rotor holder 221c with respect to the impeller 3 can be improved, and the rotational balance of the rotor portion 22 is corrected by canceling the unbalance between the impeller 3 and the rotor holder 221c. Can be performed more flexibly.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to the said embodiment, A various change is possible.

  For example, the number of protrusions 3121 of the impeller 3 is not limited to four, and may be any number as long as it is two or more. The number of fixing holes 2214 of the rotor holder 221 is not limited to twice the number of protrusions 3121, and may be an integer multiple of 3 or more. If the number of fixing holes 2214 is larger than the number of protrusions 3121 and the number of orientations of the rotor holder 221 with respect to the cup portion 31 into which the protrusions 3121 can be inserted into the fixing holes 2214 is larger than the number of protrusions 3121, The number of the fixing holes 2214 and the protrusions 3121 may be arbitrarily set, and the positions of the fixing holes 2214 and the protrusions 3121 may not be equally spaced in the circumferential direction.

  In fixing the rotor holder 221 to the cup portion 31 of the impeller 3, the method of melting the tip of the protrusion 3121 is not limited to thermal welding or ultrasonic welding, and other methods may be used. It may be a thing.

  The cup part 31 of the impeller 3 may not cover the entire side part 2211 and the cover part 2212 of the rotor holder 221, and may cover at least a part of the side part 2211 and at least a part of the cover part 2212.

  The blower fan 1 is not limited to an axial fan that sends air in the central axis direction, and may be a centrifugal fan that sends air in a direction perpendicular to the central axis.

It is a longitudinal cross-sectional view of the ventilation fan which concerns on 1st Embodiment. It is a longitudinal cross-sectional view of an impeller and a rotor part. It is an exploded view of an impeller and a rotor part. It is a bottom view of an impeller. It is a bottom view of a rotor holder. It is a bottom view of the other example of a rotor holder. It is a bottom view of the rotor holder which concerns on 2nd Embodiment. It is a bottom view of the rotor holder which concerns on 3rd Embodiment.

Explanation of symbols

1 Blower fan
2 Motor part 3 Impeller 31 Cup part 32 Wings 221, 221a to 221c Rotor holder 312 (Cup part) Lid part 2211 (Rotor holder) Lid part 2212 (Rotor holder) Lid part 2214, 2214a to 2114c Fixing hole 3121 Projection J1 Central axis L (fixed hole) length W (fixed hole) width

Claims (8)

A blower fan,
A motor unit having a substantially cylindrical rotor holder with a lid;
An impeller having a covered substantially cylindrical cup portion that covers at least a part of the outer surface of the rotor holder and at least a part of the upper surface, and a plurality of blades that protrude radially outward from the cup portion and are arranged in an annular shape;
With
The upper part of the rotor holder is arranged in a circumferential direction centering on the central axis of the motor unit, and a plurality of hole portions each having a circumferential length longer than a radial width centering on the central axis Have
The upper portion of the cup portion protrudes from the lower surface toward the rotor holder and is inserted into the plurality of hole portions, and has a plurality of protrusions that fix the rotor holder to the cup portion by being crushed by melting. A blower fan. It is a ventilation fan of Claim 1, Comprising:
The blower fan, wherein a length of the plurality of hole portions in the circumferential direction is twice or more a diameter of the plurality of protrusions. It is a ventilation fan of Claim 1 or 2, Comprising:
The number of the plurality of holes is larger than the number of the plurality of protrusions,
The blower fan, wherein the number of orientations of the rotor holder relative to the cup portion into which the plurality of projections can be inserted into the plurality of hole portions is greater than the number of the plurality of projections. It is a ventilation fan of Claim 3, Comprising:
The plurality of holes and the plurality of protrusions are arranged at equal intervals in the circumferential direction,
The blower fan, wherein the number of the plurality of holes is an integer multiple of 2 or more of the number of the plurality of protrusions. It is a ventilation fan in any one of Claims 1 thru | or 4, Comprising:
By making the length in the circumferential direction of at least one of the plurality of holes different from the length in the circumferential direction of the other holes, an unbalance of rotation about the central axis in the rotor holder is achieved. A blower fan characterized by being reduced in advance. A blower fan,
A motor section having a substantially cylindrical rotor holder with a lid;
An impeller having a covered substantially cylindrical cup portion that covers at least a part of the outer surface of the rotor holder and at least a part of the upper surface, and a plurality of blades that protrude radially outward from the cup portion and are arranged in an annular shape;
With
The upper part of the rotor holder has a plurality of holes arranged in a circumferential direction around the central axis of the motor part,
The upper portion of the cup portion protrudes from the lower surface toward the rotor holder and is inserted into the plurality of hole portions, and has a plurality of protrusions that fix the rotor holder to the cup portion by being crushed by melting.
The number of the plurality of holes is larger than the number of the plurality of protrusions,
The blower fan, wherein the number of orientations of the rotor holder relative to the cup portion into which the plurality of projections can be inserted into the plurality of hole portions is greater than the number of the plurality of projections. It is a ventilation fan of Claim 6, Comprising:
The plurality of holes and the plurality of protrusions are arranged at equal intervals in the circumferential direction,
The blower fan, wherein the number of the plurality of holes is an integer multiple of 2 or more of the number of the plurality of protrusions. It is a ventilation fan in any one of Claim 1 thru | or 7, Comprising:
The blower fan, wherein the tips of the plurality of protrusions are melted and crushed by heat welding or ultrasonic welding.

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