JP2007218101A - Axial fan and housing for axial fan - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce noise caused by turbulence of air current while using a housing formed as a structure including a tapered surface on an inside surface by a process including injection molding in an axial fan. <P>SOLUTION: The tapered surface 321 is provided on the inside surface of an outer frame part 32 in the housing 3. One end side of each rib 33 is connected to an attachment part 31 which forms a part of a stator part of a motor part, and another end side is connected to a base part 34 bulging from the tapered surface 321. Two surfaces connected to the tapered surface 321 at the base part 34 and arranged in a circumference direction having a center on a center axis J1 formed in inclined surfaces 342 separating from a center of the rib 33 as it separates from the center axis J1. Consequently, turbulence of air current generated by the base part 34 between the rib 33 and the outer frame part 32 can be inhibited and noise caused by turbulence of air current can be reduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an axial fan housing formed by a process including injection molding, and an axial fan using the housing.

  2. Description of the Related Art Conventionally, a cooling fan has been used in various electronic devices in order to cool the inside of a casing and specific electronic components, and an axial fan is known as a kind of cooling fan. An axial fan includes a motor unit having an impeller that rotates about a predetermined center axis, and a housing in which the motor unit is disposed, and the housing surrounds the periphery of the motor unit along the center axis. Part. Inside the outer frame part, the stator part of the motor part is attached to the attachment part arranged in the vicinity of one end of the outer frame part in the central axis direction, or a part of the stator part is used as the attachment part. The mounting portion is fixed to the outer frame portion by a plurality of ribs extending from the mounting portion toward the inner surface of the outer frame portion in a direction perpendicular to the central axis. Usually, in such a fan, the outer frame portion, the mounting portion, and the plurality of ribs are integrally formed by resin injection molding, so that the manufacturing cost of the housing can be reduced.

Also, in recent years, in order to improve the cooling efficiency of the axial fan, the distance from the end to which the rib of the outer frame portion is connected on the inner surface of the outer frame portion toward the central portion gradually decreases. A tapered surface is formed. In this case, in the housing formed by injection molding, a base portion that protrudes from the taper surface and connects to the end of the rib is formed due to various circumstances such as mold design limitations and die durability. (See FIG. 1 of Patent Document 1 as an example of a housing having a base portion.) In such a housing, the width of the base portion is usually larger than the width of the rib in the circumferential direction around the central axis.
JP 2000-303998 A

  By the way, in recent years, there has been an increasing demand for noise reduction in various electronic devices, and accordingly, noise reduction is also required in cooling fans. However, in the axial fan having a tapered surface in the housing, there is a problem that the airflow generated by the rotation of the impeller is disturbed by the base portion on the inner side surface of the outer frame portion, and noise is generated.

  The present invention has been made in view of the above problems, and in an axial fan, it is possible to reduce noise caused by air flow turbulence while using a housing formed as a structure having a tapered surface by a process including injection molding. It is aimed.

  The invention according to claim 1 is an axial fan housing formed by a process including injection molding, and a mounting portion to which a stator portion of a motor portion having an impeller is attached or becomes a part of the stator portion And an annular outer frame that surrounds a space in which the motor unit is to be disposed with a central axis of the motor unit as a center, and a rib that connects the mounting unit and the outer frame. The inner surface of the portion has a tapered surface in which the distance from the central axis gradually decreases from the vicinity of the position connecting to the rib with respect to the central axis direction toward the rotor portion of the motor unit; For the mold separation in the central axis direction at the time of injection molding, the part includes a base part that protrudes from the tapered surface and is connected to the rib, and at least a position of the base part that is connected to the rib, Above At least one surface of two surfaces arranged in a circumferential direction around the central axis together with the contact with the inner surface of the frame portion has an inclined surface away from the center line of the rib farther from the central axis.

  The invention according to claim 2 is the housing of the axial fan according to claim 1, wherein the other surface of the two surfaces of the base portion becomes the center of the rib as the distance from the central axis increases. Having another inclined surface away from the line.

  Invention of Claim 3 is a housing of the axial fan of Claim 1 or 2, Comprising: The angle | corner which the said inclined surface and the said centerline of the said rib make becomes large, so that it leaves | separates from the said center axis. .

  According to a fourth aspect of the present invention, there is provided the axial fan housing according to any one of the first to third aspects, wherein the mounting portion is fixed to the outer frame portion by a plurality of ribs. Of the two surfaces of each of the plurality of base portions connected to the rib, a surface on the same side with respect to the circumferential direction has the inclined surface.

  A fifth aspect of the present invention is the axial fan housing according to any one of the first to fourth aspects, wherein the inclined surface is formed by the mold during the injection molding.

  A sixth aspect of the present invention is the axial fan housing according to the fifth aspect, wherein an outer shape of a cross section of the outer frame portion perpendicular to the central axis includes a straight portion, and the tapered surface. A region where the straight line portion is centered on a portion closest to the inner side surface of the outer frame portion is a specific taper surface whose angle with the central axis is smaller than other regions, and the base The part is disposed on the specific tapered surface.

  A seventh aspect of the present invention is the housing of the axial fan according to any one of the first to sixth aspects, wherein the width of the rib increases as the distance from the central axis increases in the vicinity of the connection position with the base portion. And the said rib and the said inclined surface of the said base part are connected smoothly.

  The invention according to claim 8 is an axial fan, wherein the housing of the axial fan according to any one of claims 1 to 7 and the rotor part have an impeller, and the stator part is attached to the mounting part of the housing. Or a motor part in which the attachment part is a part of the stator part.

  According to the present invention, in the axial flow fan, by suppressing the turbulence of the air flow generated by the base portion between the rib and the outer frame portion of the housing formed as a structure having a tapered surface by a process including injection molding. , Noise caused by the turbulence of the airflow can be reduced.

  Further, in the inventions of claims 2, 3 and 7, the turbulence of the airflow can be further suppressed. In the invention of claim 4, the housing in which the mounting portion is firmly fixed to the outer frame portion by the plurality of ribs. In the axial flow fan having the above, the turbulence of the airflow can be significantly suppressed.

  In the invention of claim 5, an axial fan housing capable of reducing noise caused by the turbulence of the airflow can be easily manufactured by injection molding. By reducing the height of the base part that causes turbulence, noise caused by the turbulence of the airflow can be further reduced.

  FIG. 1 is a longitudinal sectional view of an axial fan 1 according to an embodiment of the present invention. The axial fan 1 includes a motor unit 2 that rotates about a predetermined central axis J1 and a housing 3 in which the motor unit 2 is provided. The motor unit 2 includes a rotor unit 21 that is a rotating body and a stator unit 22 that is a fixed body. The rotor unit 21 is rotatably supported with respect to the stator unit 22 by a bearing mechanism using fluid dynamic pressure caused by oil. Is done.

  The rotor section 21 has a substantially bowl-shaped rotor body 211 that opens toward the stator section 22, and an annular field magnet 212 that is magnetized in multiple poles and that has a central axis J1 as its center. The field magnet 212 is fixed to the inner peripheral surface of the rotor body 211. At the center of the rotor body 211, an annular projection 213 is formed that is annular about the central axis J1 and protrudes toward the stator portion 22, and one end (fixed end) of the shaft 214 is formed on the annular projection 213. Inserted and fixed.

  The rotor unit 21 further includes an impeller 215 that has a substantially cylindrical shape centered on the central axis J1 and into which the rotor body 211 is inserted along the central axis J1. A plurality of blades 216 are formed on the outer peripheral surface of the impeller 215, and the end of the impeller 215 opposite to the stator portion 22 protrudes toward the central axis J <b> 1 and is opposite to the stator portion 22 of the rotor body 211. An annular flange portion 217 that abuts the surface is provided.

  The stator portion 22 has a cylindrical sleeve 221 made of an oil-containing porous metal body, and a sleeve holding portion 222 formed of resin. A sleeve 221 is inserted into the bottomed cylindrical sleeve holding portion 222, and the free end side of the shaft 214 is inserted into the sleeve 221. Thereby, the shaft 214 is rotatably supported by the sleeve 221 via the oil on the free end side. A thrust plate 223 is provided at a position facing the free end surface of the shaft 214 on the bottom surface in the sleeve holding portion 222. The thrust plate 223 is formed of a low-friction synthetic resin material and supports the shaft 214 with respect to the central axis J1 direction. An armature 224 is disposed around the sleeve holding portion 222. The armature 224 is connected to the current supply circuit 225, and the current supplied is controlled, so that the drive mechanism constituted by the field magnet 212 and the armature 224 of the rotor portion 21 generates torque (rotational force). Then, the rotor part 21 is rotated with respect to the stator part 22 with the shaft 214 as the rotation axis.

  The housing 3 has a disc shape centered on the central axis J1, an attachment portion 31 formed integrally with the sleeve holding portion 222 of the stator portion 22, and an annular shape surrounding the motor portion 2 around the central axis J1. And a plurality of ribs 33 extending from the attachment portion 31 in the direction perpendicular to the central axis J1 toward the inner surface of the outer frame portion 32, and the attachment portions 31 are formed by the plurality of ribs 33. It is firmly fixed to the outer frame portion 32. The inner side surface of the outer frame portion 32 has a central annular surface 322 having a constant diameter at the center in the direction of the central axis J1 (that is, parallel to the central axis J1), and ribs 33 from the central annular surface 322 with respect to the central axis J1 direction. A tapered annular surface 321 in which the distance from the central axis J1 gradually increases toward the connecting position, and the central axis as the distance from the central annular surface 322 increases on the opposite side of the central annular surface 322 from the annular surface 321. It has another tapered annular surface 323 whose distance to J1 gradually increases. In the following description, the annular surface 321 connected to the rib 33 out of the two tapered annular surfaces 321 and 323 is referred to as a “tapered surface 321”. In the cross section of the housing 3 including the central axis J1 illustrated in FIG. 1, the edge of the tapered surface 321 is linear, but a tapered surface in which the edge is curved may be provided in the housing 3.

  In the axial fan 1, when the impeller 215 rotates, the gas in the vicinity of one end of the housing 3 (for example, the end on the annular surface 323 side) in the direction of the central axis J1 is sucked into the housing 3, While moving in the rotation direction of the impeller 215, the air is discharged from the other end (for example, the end on the tapered surface 321 side) side of the housing 3 and blown. At this time, since the annular surface 323 and the tapered surface 321 are formed on the inner surface of the outer frame portion 32, the blowing efficiency in the axial fan 1 is improved.

  2 is a perspective view showing the housing 3, FIG. 3 is a bottom view showing the housing 3, and FIG. 4 is a longitudinal sectional view of the housing 3 at a position indicated by an arrow AA in FIG. FIGS. 2 and 3 (and FIGS. 5, 6, 8, 9 and 13 to 15 described later) show the case where the housing 3 is viewed from the mounting portion 31 side, and FIGS. Then, the vertical direction of the central axis J1 is opposite to the case of FIG.

  In the housing 3, an annular outer frame portion 32 (see FIG. 1) surrounding a space in which the motor portion 2 is to be arranged with the central axis J <b> 1 as a center is an outer shape of a cross section perpendicular to the central axis J <b> 1 as shown in FIG. 3. Is approximately square. 1 is a longitudinal sectional view of the axial fan 1 at a position corresponding to a diagonal line of the square in the housing 3 of FIG.

  Further, as described above, the inner side surface of the outer frame portion 32 in FIG. 4 is directed from the vicinity of the position where it is connected to the rib 33 in the direction of the central axis J1 toward the rotor portion 21 side of the motor portion 2 to be arranged. (Ie, downward in FIG. 4) is provided with a tapered surface 321 in which the distance from the central axis J1 gradually decreases. As shown in FIG. 3, in the tapered surface 321, the area inside the center of each side in the square cross section (perpendicular to the central axis J 1) of the outer frame portion 32 is an angle formed with the central axis J 1 (in FIG. 4). (The angle represented by the symbol α1) is smaller than the other regions (in FIG. 3, it is almost 0). In each of the plurality of ribs 33, the end on the central axis J <b> 1 side is connected to the outer peripheral surface of the mounting portion 31, and the end on the opposite side to the central axis J <b> 1 is connected to the outer frame portion 32.

  As for the connection between the rib 33 and the outer frame portion 32, in detail, at the position on the tapered surface 321 to which each rib 33 is connected, as shown in FIG. 2, the end of the corresponding rib 33 from the tapered surface 321. A base portion 34 is formed so as to protrude toward the bottom, and the rib 33 is fixed to the outer frame portion 32 by being connected to the base portion 34. A surface 341 of each base portion 34 facing the central axis J1 (a surface connected to the end of the rib 33, hereinafter referred to as a “connection surface 341”. However, in FIG. 2, the connection surface 341 of one base portion 34 is shown. In the above, the distance from the central axis J1 at each position is the same as the radius of the central annular surface 322, and extends from the connection surface 341 to the central annular surface 322. A plane parallel to the central axis J1 is formed. In the housing 3, the boundary between the rib 33 and the base portion 34 in the direction in which the rib 33 extends coincides with the position of the central annular surface 322, and the central axis J 1 side is the rib 33 from the central annular surface 322. Also, the outer frame portion 32 side is a base portion 34.

  FIG. 5 is an enlarged view showing the vicinity of one base portion 34 of the housing 3. In FIG. 5, the base portion 34 is shaded in parallel. In the base portion 34, each of the two surfaces that are in contact with the tapered surface 321 and are arranged in the circumferential direction centered on the central axis J1 (that is, the direction along the central annular surface 322 in FIG. 5) is separated from the central axis J1. (Refer FIG. 3) It is set as the inclined surface 342 which leaves | separates from the centerline 331 of the rib 33. FIG. Here, the center line 331 of the rib 33 extends along the direction in which the rib 33 extends, and passes through the center (center of gravity) of the cross section of the rib 33 perpendicular to this direction (actually a triangular cross section as will be described later). It is.

  On the cross section perpendicular to the central axis J1, the angle formed between the tangent line at each position of the inclined surface 342 of the base portion 34 and the center line 331 of the rib 33 increases as the distance from the central axis J1 increases, and the inclined surface 342 on this cross section. The edge shape is a smooth curve. In the vicinity of the boundary between the inclined surface 342 and the tapered surface 321, the angle formed by the inclined surface 342 and the tapered surface 321 (that is, the angle indicated by the arrows denoted by reference signs θ 1 and θ 2 in FIG. 5) is a fine acute angle. Thus, the inclined surface 342 and the tapered surface 321 are smoothly continuous. In the base portion 34, the width in the direction perpendicular to the central axis J <b> 1 and the center line 331 of the rib 33 is made wider than the width of the rib 33 in the direction, and the rib 33 is strong against the outer frame portion 32 by the base portion 34. Fixed to.

  Next, formation of the base part 34 in the manufacture of the housing 3 will be described. In the following description, in order to make it easy to understand how the base portion 34 is formed, a housing 3 in which the position of the base portion 34 is slightly different from the housing 3 in FIGS. However, the housing 3 shown in FIGS. 2 and 3 is manufactured in the same manner as the housing 3 shown in FIG.

  The housing 3 in the present embodiment is formed by resin injection molding using a predetermined mold. FIG. 7 is a view showing an upper die 91 and a lower die 92 for molding the inner surface of the outer frame portion 32 of the housing 3 of FIG. 6, the plurality of ribs 33, and the attachment portion 31. In the upper mold 91 and the lower mold 92, illustrations of portions related to molding of other parts other than the base part 34 of the housing 3 are omitted as appropriate.

  In the upper die 91 shown in FIG. 7, a region 911 with parallel diagonal lines is an inclined surface with parallel diagonal lines of the corresponding base portion 34 in the housing 3 of FIG. 6 (indicated by reference numeral 342a in FIG. 6). In the lower mold 92, a region 921 with a parallel diagonal line is a part for molding a connection surface 341 with a parallel diagonal line of the corresponding base portion 34 in the housing 3 of FIG.

  In the manufacture of the housing 3 in FIG. 6, the upper mold 91 and the lower mold 92 in FIG. 7 are combined with each other in a space surrounded by another outer shape molding mold for molding the outer shape of the outer frame portion 32. The resin is injected into the space formed by these molds. After the injected resin is cooled and solidified, the outer shape molding die is removed, and then the upper die 91 and the lower die 92 are formed along the central axis J1 of the housing 3 being formed. They are separated in opposite directions. Thus, the housing 3 is formed while molding the inner side surface of the outer frame portion 32 (that is, the tapered surface 321, the central annular surface 322, the annular surface and the base portion 34), the plurality of ribs 33, and the attachment portion 31. At this time, the parting line by the upper mold 91 and the lower mold 92 on the inner side surface of the housing 3 becomes a boundary line between the tapered surface 321 and the central annular surface 322 except for the position where the base portion 34 is provided. As can be seen from the shape of the region 921 of the lower mold 92 in FIG. 7, the cross section of each rib 33 of the housing 3 is substantially triangular.

  Here, the reason for the existence of the base portion 34 in the housing 3 will be described with reference to FIGS. 6 and 7. At the time of injection molding of the housing 3, the rib 33 is molded by injecting resin into a space surrounded by both sides in the direction of the central axis J <b> 1 by the upper mold 91 and the lower mold 92. In order to easily separate the molds 91 and 92 for molding the inner shape of the housing 3 only by separating the 91 and the lower mold 92 from each other in the direction of the central axis J1, the ribs 33 side of the central annular surface 322 can be easily separated. The tapered surface 321 extending outward from the central annular surface 322 is usually molded by the upper mold 91. However, on the tapered surface 321 of the outer frame portion 32, a portion sandwiched between the rib 33 and the central annular surface 322 (hereinafter referred to as “target region”) interferes with the rib 33 because the rib 33 interferes. It cannot be molded and must be molded in a part of the lower mold 92 (here, a part of the region 921). In this case, since the lower mold 92 molds the central annular surface 322 whose distance from the central axis J1 is a constant value shorter than the distance on the tapered surface 321, the region of interest is also between the central axis J1. The distance between the central annular surface 322 is molded to be the same as that of the central annular surface 322, and there is a portion (that is, the base portion 34) that protrudes from the tapered surface 321 in the housing 3. As described above, the base portion 34 (a part thereof) is provided for mold separation in the direction of the central axis J1 during injection molding.

  On the other hand, in order to ensure a certain durability in the mold, it is a precondition that the molds that are in contact with each other are in contact with each other with a surface having a certain size or more (that is, in surface contact), as shown in FIG. Also for the upper mold 91 and the lower mold 92, a section 923 for molding the rib 33 of the lower mold 92 (that is, a cross section perpendicular to the direction in which the groove for molding the rib 33 extends is the region 921 in FIG. This is a part having the same shape, and is hereinafter referred to as “rib molding part 923. In FIG. 7, only one rib molding part is provided with a reference numeral.) In FIG. The two contact surfaces 922 extending in parallel with the grooves for forming the ribs 33 (indicated by parallel diagonal lines in FIG. 7) are in contact with the corresponding surfaces of the upper mold 91. Since the end surface facing the outside of the rib molding portion 923 becomes a region 921 for molding the connection surface 341 of the base portion 34, the width of the connection surface 341 of the base portion 34 in the circumferential direction centering on the central axis J 1 is the rib 33. The base portion 34 that is thicker than the rib 33 by a width corresponding to the two contact surfaces 922 (the width corresponding to each contact surface 922 is, for example, 1 mm [mm] or more). Is formed.

  Actually, in the outer frame portion 32, the lower mold 92 is formed so that the diameter of the central annular surface 322 gradually decreases at a very small rate toward the tapered surface 321 side. It is possible to smoothly separate the lower mold 92 during molding.

  Next, a general housing formed by injection molding will be described as a comparative example for the housing 3. FIG. 8 is a perspective view showing the housing 8 of the comparative example, and FIG. 9 is a bottom view showing the housing 8 of the comparative example. Also on the inner side surface of the outer frame portion 82 of the housing 8 of the comparative example, the central annular surface 822 whose diameter is substantially constant at the center in the central axis J2 direction, and the rib 83 from the central annular surface 822 side in the central axis J2 direction. A tapered surface 821 is formed in which the distance from the central axis J2 gradually increases toward the connecting position. Further, since the housing 8 of the comparative example is formed by injection molding, the base portion 84 is formed in the same manner as the housing 3 described above. However, in the base portion 84 of the housing 8 of the comparative example, the tapered surface 821 of the outer frame portion 82 is formed. Both of the two surfaces that are in contact with each other and are arranged in the circumferential direction around the central axis J2 are planes parallel to the central line 831 (see FIG. 9) of the rib 83 and the central axis J2.

  Next, measurement results of noise generated when the axial fan 1 having the housing 3 and the axial fan having the housing 8 of the comparative example are actually driven will be described. Here, since the rotational speed of the motor part of each axial fan is 3200 times per minute and the number of blades of the impeller is 7, the blade primary component of noise generated by the rotation of the axial fan is (3200/60 × 7 = 373 [Hz]).

  FIG. 10 is a diagram showing measurement results of noise generated when the axial fan 1 having the housing 3 is driven, and FIG. 11 is generated when the axial fan having the housing 8 of the comparative example is driven. It is a figure which shows the measurement result of noise. FIG. 12 is an enlarged view showing a portion corresponding to a specific frequency band in the measurement results of FIGS. 10 and 11. In FIG. 12, the measurement result for the axial fan 1 having the housing 3 is indicated by a solid line denoted by reference numeral 71, and the measurement result for the axial fan having the housing 8 of the comparative example is indicated by a broken line denoted by reference numeral 72.

  From FIG. 12, the axial flow having the axial fan 1 having the housing 3 and the housing 8 of the comparative example near the blade secondary component (746 Hz) and the blade tertiary component (1119 Hz) of the noise generated by the rotation of the axial fan. It can be seen that there is a large difference in sound pressure level between fans. In the overall value of the sound pressure level, the axial fan 1 having the housing 3 is 22.4 dB (A), the axial fan having the housing 8 of the comparative example is 23.0 dB (A), and the axial fan 1 is Compared to the comparative example, the sound pressure level is reduced by 0.6 dB (A).

  As described above, in the housing 3 of the axial fan 1, the base portion 34 that protrudes from the tapered surface 321 is provided on the outer frame portion 32 for separating the mold in the direction of the central axis J1 during injection molding. The fixing rib 33 of the attachment portion 31 is connected to the outer frame portion 32 via the portion 34. Then, each of the two surfaces connected to the tapered surface 321 in the base portion 34 and arranged in the circumferential direction around the central axis J1 is an inclined surface 342 that is separated from the center line 331 of the rib 33 as the distance from the central axis J1 increases. The Thereby, in the axial fan 1, the base part 34 between the rib 33 and the outer frame part 32 is improved while using the housing 3 formed as a structure having a tapered surface by a process including injection molding. It is possible to reduce the noise caused by the turbulence of the airflow by suppressing the turbulence of the airflow generated by the above.

  FIG. 13 is a bottom view showing a housing 3 according to another example. Also in the outer frame portion 32 of the housing 3 in FIG. 13, the outer shape of the cross section perpendicular to the central axis J <b> 1 is substantially square, and each side of the square of the tapered surface 321 is closest to the inner surface of the outer frame portion 32. A region centered at the position to be moved (region denoted by reference numeral 321a in FIG. 13 and hereinafter referred to as “specific taper surface”) has an angle formed with the central axis J1 smaller than other regions. . That is, at each position in the direction of the central axis J1, the distance between the specific taper surface 321a and the central axis J1 is smaller than the distance in other regions on the tapered surface 321.

  In the housing 3 shown in FIG. 13, a base portion 34 that connects each rib 33 and the outer frame portion 32 is disposed on the specific tapered surface 321a. Thereby, compared with the case where it forms in the other area | region on the taper surface 321, the height (length which goes to the center axis J1 side from the taper surface 321) of the base part 34 becomes low. Thereby, in the housing 3 of FIG. 13 formed by the process including injection molding, the turbulence of the airflow in the base portion 34 can be further suppressed, and the noise caused by the turbulence of the airflow can be further reduced. Note that, depending on the design of an electronic device or the like in which the axial fan 1 is provided, the lead wire for supplying electric power to the motor unit 2 of the axial fan 1 is positioned at the apex of the square section of the outer frame portion 32 perpendicular to the central axis J1. In this case, it is preferable to use the housing 3 of FIG. 3 in which the rib 33 extends toward the vicinity of the apex of the square section of the outer frame portion 32.

  FIG. 14 is a bottom view showing a housing 3 according to still another example, and shows an enlarged vicinity of a connection position between one rib 33 and a base portion 34. Also in FIG. 14, the base portion 34 is shaded in parallel.

  In each rib 33 provided in the housing 3 of FIG. 14, the distance from the central axis J1 (see FIG. 3) in the vicinity of the connection position with the base portion 34 (that is, the outer frame portion 32 side along the center line 331 of the rib 33). The width of the rib 33 is increased (as it goes to), and the surface of the rib 33 and the inclined surface 342 of the base portion 34 are smoothly connected. That is, in the cross section perpendicular to the central axis J <b> 1 of the housing 3, an edge from the end portion of the rib 33 on the base portion 34 side to the tapered surface 321 through the base portion 34 is curved. Thereby, in the axial flow fan 1 having the housing 3 of FIG. 14 formed by a process including injection molding, the turbulence of the airflow generated at the edge on the central axis J1 side of the base portion 34 in the housing 3 shown in FIG. 3 is also suppressed. Thus, it is possible to further suppress the noise caused by the turbulence of the airflow in the axial fan 1. Note that the mold for forming the housing 3 in FIG. 14 has a more complicated shape than that for forming the housing 3 in FIG. It is preferable to use the housing 3. Moreover, the rib 33 and the base part 34 of the structure similar to FIG. 14 may be used for the housing 3 of FIG.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made.

  In the embodiment described above, the inclined surface 342 is formed by a mold during injection molding, so that the housing 3 of the axial fan 1 that can reduce noise caused by the turbulence of the airflow can be easily formed by injection molding. Although it is realized, for example, in the housing 8 of the comparative example of FIG. 9 formed by injection molding, the base portion 84 is ground so that the taper surface in each base portion 84. Even if an inclined surface that is separated from the center line 831 of the rib 83 is formed on two surfaces (hereinafter referred to as “specific side surfaces”) that are in contact with 821 and are arranged in the circumferential direction centering on the central axis J2, the distance from the central axis J2 increases. Good. That is, in a housing formed by a process including injection molding that requires the formation of a base portion, by providing an inclined surface on a specific side surface of the base portion, noise due to turbulence of airflow in the axial fan can be reduced. It becomes possible. In addition to the resin injection molding, the housing may be formed by a process including injection molding using a metal material such as aluminum.

  In the housing 3 of the axial fan 1, even if the inclined surface 342 is formed only on one specific side of the two specific side surfaces of each base portion 34, the turbulence of the airflow can be suppressed to some extent. is there. In other words, in the housing 3, it is important that at least one specific side surface of the two base portions 34 is in contact with the tapered surface 321 and at least one of the specific side surfaces arranged in the circumferential direction has the inclined surface 342. However, in the case where the inclined surface 342 is formed only on one specific side surface in the housing 3, each of the plurality of base portions 34 connected to the plurality of ribs 33 can be used to significantly suppress the turbulence of the airflow in the axial fan. The specific side surface of the two specific side surfaces on the same side with respect to the circumferential direction (actually, the upstream side in the rotation direction of the impeller 215 when the motor unit 2 is disposed) may be the inclined surface 342. preferable. Of course, it is possible to further suppress the turbulence of the air flow by providing the inclined surfaces 342 on both of the two specific side surfaces of each base portion 34 as in the above embodiment.

  Further, the entire specific side surface does not necessarily have to be the inclined surface 342, and the inclined surface may be partially provided on the specific side surface. However, normally, the end of the base 34 opposite to the central annular surface 322 in the direction of the central axis J1 is a portion connected to the rib 33, and in this portion, the taper surface 321 of the base 34 is directed to the central axis J1. In consideration of the fact that the ratio of the height of the direction becomes the largest and contributes to the turbulence of the airflow, the inclined surface is preferably formed at a position connected to at least the rib 33 of the base portion 34 on the specific side surface. . In this case, in order to efficiently suppress the turbulence of the airflow on the inclined surface, it is assumed that the specific side surface is formed in parallel to the direction in which the rib 33 extends (in the case of FIG. 9). It is preferable that a portion corresponding to half or more of the length in the direction is an inclined surface.

  In the housing 3, the inclined surface of the base portion 34 may have various shapes as long as the inclined surface is provided so as to be farther from the center line of the rib 33 as being farther from the central axis J <b> 1. For example, depending on the design of the mold for molding the inner shape of the housing 3, as shown in FIG. 15, the width of the rib 33 on the boundary between the rib 33 and the base portion 34 is the same as the width of the base portion 34. In addition, an inclined surface 342 that smoothly continues from the surface of the rib 33 may be formed on the base portion 34. In addition, an inclined surface may be provided on the cross section perpendicular to the central axis J1 of the housing 3 so that the edge has a linear shape. However, in order to further suppress the turbulence of the airflow in the axial fan 1, the angle formed by the inclined surface 342 of the base portion 34 and the center line 331 of the rib 33 increases as the distance from the center axis J <b> 1 increases. The shape of the edge of the inclined surface 342 on a cross section perpendicular to J1 is preferably a smooth curve.

  In the axial fan 1 of FIG. 1, the attachment portion 31 is formed integrally with the sleeve holding portion 222 and is a part of the stator portion 22. However, the sleeve holding portion 222 and the attachment portion 31 are separate members. The stator part 22 of the motor part 2 may be formed and attached to the attachment part 31.

  In the housing 3 of FIG. 13, the outer shape of the cross section perpendicular to the central axis J1 of the outer frame portion 32 is a square, but various shapes are conceivable as the outer frame portion of the housing, for example, the cross section of the outer frame portion. The outer shape may be a substantially circular shape in which a part of the circumference is a straight portion. In this case, an area centered on a portion of the taper surface where the straight line portion is closest to the inner side surface of the outer frame portion is a specific taper surface whose angle formed with the central axis J1 is smaller than the other regions, and the specific taper A relatively low base is placed on the surface. Thereby, the turbulence of the airflow generated in this base part is suppressed.

  As described above, from the viewpoint of further suppressing the turbulence of the airflow generated in the base portion by reducing the height of the base portion that causes the turbulence of the airflow, the cross section of the cross section perpendicular to the central axis J1 of the outer frame portion. The outer shape is a shape including at least a straight portion, and the region of the tapered surface centering on the portion where the straight portion is closest to the inner surface of the outer frame portion has an angle with the central axis J1 as compared to other regions. It is important that the surface is a small specific taper surface and the base portion is disposed on the specific taper surface.

  In the housing 3, the rib 33 that fixes the attachment portion 31 to the outer frame portion 32 does not necessarily extend perpendicular to the central axis J <b> 1, and is perpendicular to the central axis J <b> 1 from the outer peripheral surface of the attachment portion 31. May be inclined and extended, and connected to the outer frame portion 32 at a position different from the attachment portion 31 in the direction of the central axis J1.

It is a longitudinal cross-sectional view of an axial fan It is a perspective view which shows a housing. It is a bottom view which shows a housing. It is a longitudinal cross-sectional view of a housing. It is a figure which expands and shows a base part vicinity. It is a perspective view which shows a housing. It is a figure which shows an upper mold and a lower mold. It is a perspective view which shows the housing of a comparative example. It is a bottom view which shows the housing of a comparative example. It is a figure which shows the measurement result of the noise of an axial fan. It is a figure which shows the measurement result of the noise of an axial fan. It is a figure which shows the measurement result of the noise of an axial fan. It is a figure which shows the other example of a housing. It is a figure which shows the further another example of a housing. It is a figure which shows the further another example of a housing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Axial fan 2 Motor part 3 Housing 21 Rotor part 22 Stator part 31 Mounting part 32 Outer frame part 33 Rib 34 Base part 91,92 Mold 215 Impeller 321 Tapered surface 321a Specific taper surface 331 Center line 342, 342a Inclined surface J1 Central axis

Claims (8)

An axial fan housing formed by a process including injection molding,
The stator part of the motor part having an impeller is attached, or an attachment part that becomes a part of the stator part,
An annular outer frame that surrounds a space in which the motor unit is to be arranged around the central axis of the motor unit;
A rib connecting the mounting portion and the outer frame portion;
With
The inner side surface of the outer frame portion has a tapered surface in which the distance between the central axis gradually decreases from the vicinity of the position connecting to the rib in the central axis direction toward the rotor portion side of the motor unit,
The outer frame portion includes a base portion that protrudes from the tapered surface and is connected to the rib for separating the mold in the central axis direction during injection molding,
At least one of the two surfaces in contact with the inner side surface of the outer frame portion and arranged in the circumferential direction centering on the central axis at a position connecting to at least the rib of the base portion is from the central axis. A housing for an axial fan, characterized by having an inclined surface that is further away from the center line of the rib as it is further away. A housing for an axial fan according to claim 1,
The axial fan housing characterized in that the other of the two surfaces of the base portion has another inclined surface that is further away from the center line of the rib as it is further away from the central axis. A housing for an axial fan according to claim 1 or 2,
An axial fan housing characterized in that an angle formed by the inclined surface and the center line of the rib increases with distance from the center axis. A housing for an axial fan according to any one of claims 1 to 3,
The attachment portion is fixed to the outer frame portion by a plurality of ribs, and a surface on the same side with respect to the circumferential direction among the two surfaces of the plurality of base portions connected to the plurality of ribs is provided. An axial fan housing comprising the inclined surface. A housing for an axial fan according to any one of claims 1 to 4,
The axial fan housing, wherein the inclined surface is formed by the mold during the injection molding. A housing for an axial fan according to claim 5,
The outer shape of the cross section perpendicular to the central axis of the outer frame portion is a shape including a straight portion, and the straight portion of the tapered surface is centered on a portion closest to the inner side surface of the outer frame portion However, the angle formed with the central axis is a specific tapered surface smaller than other regions,
The axial fan housing, wherein the base portion is disposed on the specific taper surface. A housing for an axial fan according to any one of claims 1 to 6,
The axial fan housing characterized in that the width of the rib increases with increasing distance from the central axis in the vicinity of the connection position with the base portion, and the rib and the inclined surface of the base portion are smoothly connected. . An axial fan,
A housing for an axial fan according to any one of claims 1 to 7,
The rotor part has an impeller, the stator part is attached to the attachment part of the housing, or the motor part in which the attachment part is a part of the stator part,
An axial flow fan comprising:

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