Patent Publication Number: US-2019195236-A1

Title: Air blower

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority to Japanese Patent Application No. 2017-248020 filed on Dec. 25, 2017. The entire contents of this application are hereby incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to air blowers. 
     2. Description of the Related Art 
     Various air blowers are known in the related art. For example, a heat sink for a semiconductor device is disclosed. 
     The known heat sink for a semiconductor device includes a group of fins and a blower fan. The fin group has a shape in which a large number of plates or pins are vertically arrayed on a base. The blower fan includes a fan rotating mechanism and a centrifugal fan. The fin group and the centrifugal fan each include a cover. An air intake port is disposed in the cover of the centrifugal fan in the rotational direction. 
     However, in the known heat sink for a semiconductor device, the direction of air flow due to the rotation of the centrifugal fan with respect to the fin extending direction is not uniform, for example, parallel to or inclined with respect to the fin extending direction. The known heat sink for a semiconductor device is configured such that the fins are disposed at regular intervals, so that air flow in the gap between the fins is interrupted in a region in which the direction of air flow is inclined or perpendicular to the fin extending direction, resulting in insufficient air volume of the air blower. Furthermore, the volume of air exhausted from the exhaust port of the fin group is non-uniform in the fin array direction. 
     SUMMARY OF THE INVENTION 
     An air blower according to an example embodiment of the present disclosure includes an impeller centered on a central axis extending in a vertical direction, a motor to rotate the impeller about the central axis; and a housing structured to house the impeller. The housing includes a lower plate covering a lower side of the impeller, wherein the motor is fixed to the lower plate, a side wall covering a side of the impeller, and an upper plate covering an upper side of the impeller. At least one of the upper plate and the lower plate includes an air intake portion. An exhaust is disposed in a first direction that is a radial component of the impeller. The exhaust includes a plurality of fins. Assuming that a distance from a line segment extending from the central axis in the first direction to an array of the fins upstream of an airflow caused by rotation of the impeller is a first predetermined distance, at least a portion of the plurality of fins are disposed in a first region located upstream from the first predetermined distance and in a second region located downstream from the first predetermined distance. A distance between the plurality of fins disposed in the first region is shorter than a distance between the plurality of fins disposed in the second region. 
     The above and other elements, features, steps, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of an air blower according to an example embodiment of the present disclosure. 
         FIG. 2A  is a plan view of the air blower according to an example embodiment of the present disclosure viewed from above. 
         FIG. 2B  is an enlarged plan view of an exhaust according to an example embodiment of the present disclosure illustrating the configuration thereof. 
         FIG. 3  is a plan view of an air blower with the same configuration as the configuration in  FIG. 2A . 
         FIG. 4  is a plan view of an air blower with a heat pipe viewed from above illustrating a configuration example thereof. 
         FIG. 5  is a plan view of an air blower with a modification configuration concerning the distance between the fins. 
         FIG. 6  is a plan view of an air blower viewed from above illustrating an example embodiment in which the present disclosure is applied to a scroll air blower. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An example embodiment of the present disclosure will be described hereinbelow with reference to the drawings. In this specification, a direction in which a central axis C 1 , to be described later, extends is referred to as “vertical direction”. However, “vertical direction” is not a vertical direction when the air blower is installed in actual equipment. A radial direction about the central axis C 1  is simply referred to as “radial direction” and a circumferential direction about the central axis C 1  is simply referred to as “circumferential direction”. The “vertical direction” is sometimes referred to as “axial direction”. 
       FIG. 1  is a cross-sectional view of an air blower  1  according to an example embodiment of the present disclosure. The air blower  1  is a centrifugal fan. The air blower  1  is installed in, for example, a notebook personal computer (PC), to be used in cooling components in the casing of the notebook PC. 
     The air blower  1  includes a motor unit  2 , a housing  3 , and an impeller  4 . The impeller  4  is centered on a central axis C 1  extending in the vertical direction. The motor unit  2  rotates the impeller  4  about the central axis C 1 . The housing  3  houses the motor unit  2  and the impeller  4 . 
     The housing  3  includes an upper plate  31 , a lower plate  32 , and a side wall  33 . The upper plate  31  covers the upper side of the impeller  4 . The lower plate  32  covers the lower side of the impeller  4 . The side wall  33  covers a side of the impeller  4 . The motor unit  2  is fixed to the lower plate  32 . The upper plate  31 , the side wall  33 , and the lower plate  32  constitute a wind tunnel  30  surrounding the impeller  4 . 
     The upper plate  31  and the lower plate  32  are thin sheets made of an aluminum alloy, a stainless steel, or another metal. The side wall  33  is formed from a die-cast aluminum alloy or resin. The lower end of the side wall  33  is fixed to the periphery of the lower plate  32  by, for example, screwing. The upper plate  31  is fixed to the upper end of the side wall  33  by, for example, caulking. 
     The motor unit  2  is of an outer rotor type, as illustrated in  FIG. 1 . The motor unit  2  includes a stationary portion  21 , a rotating portion  22 , and a sleeve  23  serving as a bearing. The sleeve  23  has a substantially cylindrical shape centered on the central axis C 1 . The rotating portion  22  can be rotated about the central axis C 1  with respect to the stationary portion  21  by a shaft  221 , to be described later, and the sleeve  23 . 
     The stationary portion  21  includes a stator  210  and a bearing holding portion  24 . The bearing holding portion  24  houses the sleeve  23 . The bearing holding portion  24  has a substantially cylindrical shape centered on the central axis C 1  and is made of resin. The bearing holding portion  24  protrudes upward from the lower plate  32 . The bearing holding portion  24  is fixed to a hole  321  in the lower plate  32 . The lower end of the bearing holding portion  24  and the peripheral portion of the hole  321  are fastened by, for example, insert molding. The lower end of the bearing holding portion  24  and the peripheral portion of the hole  321  may not be fixed as described above but may be fixed by press-fitting or caulking. 
     The stator  210  has a ring shape centered on the central axis C 1  and is mounted to the outer circumferential surface of the bearing holding portion  24 . The stator  210  includes a stator core  211 , and insulator  212 , and a coil  213 . The stator core  211  is a lamination of thin electromagnetic steel sheets. The inner circumferential surface of the stator core  211  is fixed to the outer circumferential surface of the bearing holding portion  24 . The insulator  212  covers the surface of the stator core  211 . 
     The rotating portion  22  includes a shaft  221 , a yoke  222 , and a rotor magnet  223 . The shaft  221  is a rod-like member centered on the central axis C 1  and extending in the vertical direction. The upper end of the shaft  221  is fixed to a cup  41  (described later) of the impeller  4 . The yoke  222  has a substantially cylindrical shape centered on the central axis C 1  and is fixed to the inner surface of the cup  41 . The rotor magnet  223  has a substantially cylindrical shape centered on the central axis C 1  and is fixed to the inner surface of the yoke  222  and faces the stator  210  in the radial direction. 
     The shaft  221  is inserted in the sleeve  23 . The outer circumferential surface of the shaft  221  faces the inner circumferential surface of the sleeve  23  with a space therebetween. The sleeve  23  is made of an oil-retaining porous metallic material and is inserted and fixed in the bearing holding portion  24 . The bearing may be a ball bearing. 
       FIG. 2A  is a plan view of the air blower  1  viewed from above. In  FIG. 2A , the upper plate  31  is not illustrated for the sake of convenience. The impeller  4  includes the cup  41 , a plurality of blades  42 , and a connecting portion  43 . The cup  41 , the blades  42 , and the connecting portion  43  are made of resin into a single unit. As illustrated in  FIG. 2A , the rotational direction A 1  of the impeller  4  is clockwise as viewed from above. 
     The cup  41  has a covered substantially cylindrical shape centered on the central axis C 1  and opens downward. The plurality of blades  42  extend radially outward from the outer circumferential surface of the cup  41 . The blades  42  are disposed at equal intervals in the circumferential direction. The outer circumferential ends of the blades  42  are disposed behind the inner circumferential ends in the rotational direction. This makes the blades  12  inclined with respect to the radial direction. 
     The connecting portion  43  connects the upper surfaces of the outer circumferential ends of the blades  42  next to each other in the circumferential direction to form a ring shape. The upper plate  31  has an air intake hole (an air intake portion)  311  (not illustrated in  FIG. 2A , illustrated in  FIG. 1 ). The air intake hole  311  is located above the impeller  4 . The inner peripheral edge of the connecting portion  43  is disposed radially outside the air intake hole  311 . The impeller  4  is therefore exposed from the air blower  1  through the air intake hole  311  as viewed from above. 
     The air intake hole may be disposed not in the upper plate  31  but in the lower plate  32  or in both of the upper plate  31  and the lower plate  32 . If the air intake hole is provided in the lower plate  32 , a plurality of air intake holes are disposed around the central axis C 1  in the circumferential direction. In other words, at least one of the upper plate  31  and the lower plate  32  may include the air intake portion. 
     As illustrated in  FIG. 2A , the air blower  1  includes an exhaust unit  5  disposed in a first direction D 1 , which is a radial component of the impeller  4 . The exhaust unit  5  is formed by, for example, part of the lower plate  32 , a plurality of fins  51 , and part of the upper plate  31  (not illustrated in  FIG. 2A ). The plurality of fins  51  are arrayed in a direction perpendicular to the first direction D 1 . The fins  51  are plate-like members sandwiched between the upper plate  31  and the lower plate  32  from above and below and standing in the vertical direction. The plurality of fins  51  are arrayed parallel to the first direction D 1 . This allows the air to be exhausted in a fixed direction from the exhaust unit  5 . Part of the plurality of fins  51  may be nonparallel to the first direction D 1 . In some embodiments, part of the fins  51  are not sandwiched between the upper plate  31  and the lower plate  32 . 
     In the case where a heat pipe is disposed above the fins  51  (to be described later), the upper plate  31  extends to an end of the heat pipe opposite to the first direction D 1 . In this case, the exhaust unit  5  is constituted by part of the lower plate  32 , a plurality of fins  51 , and the heat pipe. The exhaust unit  5  may be made of a material different from the material of the upper plate  31  and the lower plate  32 . The heat pipe may be disposed above the fins  51 , with the upper plate  31  therebetween. 
     When the coil  213  is supplied with an electrical current, a torque about the central axis C 1  is generated between the rotor magnet  223  and the stator  210 . This causes the impeller  4  to rotate about the central axis C 1  in the rotational direction A 1 . When the impeller  4  rotates, air flows into the housing  3  through the air intake hole  311 . The air that has flowed into the housing  3  flows between adjacent blades  42  and accelerates radially outward. The air that has accelerated radial outward is blown radially outward of the impeller. The air that has been blown radially outward of the impeller  4  flows in the wind tunnel  30 , passes through a gap between adjacent fins  51 , and is discharged outward. 
     A more specific configuration of the exhaust unit  5  will be described with reference to  FIGS. 2A and 2B . In  FIG. 2A , the distance between adjacent fins  51  is regular in the array direction of the fins  51  for the sake of convenience. However, the distance between the fins  51  differs actually. The configuration is illustrated in  FIG. 2B , which is an enlarged view of the exhaust unit  5 . In  FIG. 2A , the flow of air caused by the rotation of the impeller  4  is expressed as an airflow F 1 . 
     As illustrated in  FIGS. 2A and 2B , a first predetermined distance X is assumed to be the distance from a line segment extending from the central axis C 1  in the first direction D 1  to the array of the fins  51  upstream of the airflow F 1 . A region of the exhaust unit  5  including the plurality of fins  51  includes a first region R 1  upstream of the airflow F 1  from the first predetermined distance X and a second region R 2  other than the first region R 1 . In other words, the second region R 2  is a region located downstream of the airflow F 1  from the first predetermined distance X. 
     A distance P 1  between the plurality of fins  51  disposed in the first region R 1  is smaller than distances P 3 , P 4 , and P 5  between the plurality of fins  51  disposed in the second region R 2 . In the first region R 1 , the airflow F 1  is substantially parallel to the direction in which the fins  51  extend. In the second region R 2 , the airflow F 1  is inclined with respect to or substantially perpendicular to the direction in which the fins  51  extend. Accordingly, increasing the distance between the fins  51  in the second region R 2  allows the air to easily flow in the gap between the fins  51 , thereby increasing the volume of air in the second region R 2 . Since the distances between the fins  51  in the first region R 1  and the second region R 2  are adjusted according to the direction in which air flows, the amount of exhaust air can be made uniform across the first region R 1  and the second region R 2 . 
     In  FIG. 2A  and  FIG. 2B , there is no other region along the joint between the first region R 1  and the second region R 2 . 
     As an alternative, another region in which the fin interval differs from the distances in the first region R 1  and the second region R 2  may be disposed in the joint. In other words, the other region is not the essence of the present disclosure related to the first region R 1  and the second region R 2 . This also applies to the joint between other regions, to be described below. 
     In other words, the air blower  1  of the present embodiment includes the impeller  4  centered on the central axis C 1  extending in the vertical direction, the motor unit  2  that rotates the impeller  4  about the central axis C 1 , and the housing  3  that houses the impeller  4 . The housing  3  includes the lower plate  32 , which covers the lower side of the impeller  4  and to which the motor unit  2  is fixed, the side wall  33  covering a side of the impeller  4 , and the upper plate  31  covering the upper side of the impeller  4 . At least one of the upper plate  31  and the lower plate  32  includes the air intake hole  311 . The exhaust unit  5  is disposed in the first direction D 1 , which is a radial component of the impeller  4 . The exhaust unit  5  includes the plurality of fins  51 . If the distance from the line segment extending from the central axis C 1  in the first direction D 1  to the array of the fins  51  upstream of the airflow F 1  caused by the rotation of the impeller is the first predetermined distance X, at least part of the plurality of fins  51  are disposed in the first region R 1  located upstream from the first predetermined distance X and in the second region R 2  located downstream from the first region R 1 . The distance between the plurality of fins  51  disposed in the first region R 1  is shorter than the distance between the plurality of fins  51  disposed in the second region R 2 . 
     Thus, increasing the distance between the fins  51  in the second region R 2  in which the airflow F 1  is inclined with respect to the extending direction of the fins  51  may allow the air between the fins  51  to easily flow, thereby decreasing loss in air volume between the fins  51 . This may increase the air flow rate of the air blower  1 . This may also make the air volume in the exhaust unit  5  uniform in the direction in which the fins  51  are arrayed. 
     As illustrated in  FIG. 2A , the first predetermined distance X is preferably from 0.8 (Rout) to 1.2 (Rout), where Rout is the distance from the central axis C 1  to the radially outer end of the blades  42  of the impeller  4 . 
     Thus, the small distance between the fins  51  in the first region R 1  in which the flow of air is substantially parallel to the direction in which the fins  51  extend may allow the air volume to be adjusted, so that the air volume in the exhaust unit  5  may be made uniform in the direction in which the fins  51  are arrayed. 
     As illustrated in  FIG. 2A  and  FIG. 2B , of the distance from the line segment extending from the central axis C 1  in the first direction D 1  upstream of the airflow F 1 , a distance shorter than the first predetermined distance X is assumed to be a second predetermined distance Y. The second region R 2  includes a third region R 3  next to the first region R 1  upstream of the airflow F 1  from the second predetermined distance Y. The distance P 3  between the fins  51  disposed in the third region R 3  is longer than the distance P 1  between the fins  51  disposed in the first region R 1 . 
     In the remaining region of the second region R 2  other than the third region R 3 , the distance between the fins  51  in a fifth region R 5  other than a fourth region R 4  (to be described later) is longer than the distance in the third region R 3 . In other words, in  FIG. 2B , the distance P 5  between the fins  51  disposed in the fifth region R 5  is longer than the distance P 3  between the fins  51  disposed in the third region R 3 . In the third region R 3 , the airflow F 1  is inclined more with respect to the direction in which the fins  51  extend than in the first region R 1 , and in the fifth region R 5 , the airflow F 1  is more inclined. Adjusting the distance between the fins  51  in the third region R 3  and the fifth region R 5  according to the direction of the airflow F 1  may reduce loss in air volume between the fins  51 , thereby increasing the air volume. For the fourth region R 4 , there is no limitation on the distance between the fins  51  relative to the distance between the fins  51  in the third region R 3 . In  FIG. 2B , for example, the distance P 4  between the fins  51  disposed in the fourth region R 4  is the same as the distance P 3  between the fins  51  disposed in the third region R 3 . 
     In other words, the second predetermined distance Y, which is the distance from the line segment extending from the central axis C 1  in the first direction D 1  to the array of the fins upstream of the airflow F 1  caused by the rotation of the impeller  4  is shorter than the first predetermined distance X. The second region R 2  includes the third region R 3  at the position upstream from the second predetermined distance Y and next to the first region R 1 . The distance between the plurality of fins  51  disposed in the third region R 3  is longer than the distance between the plurality of fins  51  disposed in the first region R 1  and smaller than the distance between the plurality of fins  51  disposed in the remainder of the second region R 2  other than the third region R 3 . 
     Thus, adjusting the distance between the fins  51  according to the direction of air flow may reduce loss in air volume between the fins  51 , increasing the air volume of the air blower  1 . 
     As illustrated in  FIG. 2A , the second predetermined distance Y is preferably from 0.8 (Rin) to 1.2 (Rin), where Rin is the distance from the central axis C 1  to the radially inner ends of the blades  42 . 
     Thus, setting the fin distance in the third region R 3  in which the direction of air flow is inclined with respect to the direction in which the fins  51  extend longer than the fin distance in the first region R 1  may make air between the fins  51  easy to flow to reduce loss in air volume between the fins  51 , thereby increasing the air volume of the air blower  1 . 
     As illustrated in  FIG. 2A  and  FIG. 2B , a third predetermined distance Z is assumed to be the distance from the line segment extending from the central axis C 1  in the first direction D 1  to the array of the fins  51  downstream of the airflow F 1 . The second region R 2  includes the fourth region R 4  downstream of the airflow F 1  from the third predetermined distance Z. The fourth region R 4  is positioned most downstream of the airflow F 1  in the exhaust unit  5 . 
     In the second region R 2 , a region other than the third region R 3  and the fourth region R 4  is the fifth region R 5 . Of the region of the second region R 2  other than the fourth region R 4 , the distance between the fins  51  in the fourth region R 4  is shorter than the distance between the fins  51  at least in the fifth region R 5 . In other words, in  FIG. 2B , the distance P 4  between the fins  51  disposed in the fourth region R 4  is shorter than the distance P 5  between the fins  51  disposed in the fifth region R 5 . As described above, for the fourth region R 4 , there is no limitation on the distance between the fins  51  relative to the distance between the fins  51  in the third region R 3 . 
     The side wall  33  includes a tongued portion  331  protruding toward the impeller  4 . The tongued portion  331  faces the fourth region R 4  in the first direction D 1  with a gap therebetween. This allows the airflow F 1  caused by the rotation of the impeller  4  to be guided to the fourth region R 4  using the tongued portion  331 . 
     The tongued portion  331  includes a curved surface  331 A extending from a top T facing the impeller  4  toward the fourth region R 4 . The curved surface  331 A allows the flow of air to be smoothly guided to the fourth region R 4 . 
     The airflow F 1  due to the tongued portion  331  causes the air in the fourth region R 4  to flow in the extending direction of the fins  51 . Therefore, decreasing the distance between the fins  51  in the fourth region R 4  allows the volume of air exhausted from the fourth region R 4  to be adjusted. 
     In other words, assuming that the distance from the line segment extending from the central axis C 1  in the first direction D 1  to the array of the fins  51  downstream of the airflow F 1  caused by the rotation of the impeller  4  is the third predetermined distance Z, the second region R 2  includes the fourth region R 4  downstream from the third predetermined distance Z. The distance between the plurality of fins  51  disposed in the fourth region R 4  is shorter than the distance between the plurality of fins  51  disposed in the remainder of the second region R 2  other than the fourth region R 4 . 
     This causes the air in the fourth region R 4  to flow to the exhaust side. Thus, setting the fin distance in the fourth region R 4  short may make the air volume uniform in the array direction of the fins  51  in the exhaust unit  5 . 
     On the line extending from the central axis C 1  to the fins  51 , the distance between the outer ends of the blades  42  of the impeller  4  and the inflow ends of the fins  51  is shortest at the distance MD illustrated in  FIG. 2A . The fifth region R is disposed on the line segment at the position of the distance MD. At the position of the distance MD, the direction of the airflow F 1  is substantially orthogonal to the extending direction of the fins  51 . Therefore, disposing the fifth region R 5  at the position of the distance MD in which the distance between the fins  51  is long may allow the air to flow easily through the gap between the fins  51 , increasing the air volume. 
     In other words, the second region R 2  is disposed on the line extending from the central axis C 1  toward the fins  51  at the position where the distance between the outer ends of the blades  42  of the impeller  4  and the inflow ends of the fins  51  is shortest. 
     At the position where the distance is shortest, the flow of air is substantially orthogonal to the direction in which the fins  51  extend. This makes it difficult to exhaust the air between the fins  51 . For that reason, the second region R 2  is disposed to reduce loss in air volume between the fins  51 , thereby increasing the air volume of the air blower  1 . 
     Referring to  FIG. 3 , the air blower  1  with the same configuration as the configuration in  FIG. 2A  will be described. On a straight line connecting the central axis C 1  and a boundary position P 1  upstream of the airflow F 1  at which the inner surface of the side wall  33  and the inflow end of the exhaust unit  5  intersect, a line segment L 1  connects the outer ends of the blades  42  of the impeller  4  and the boundary position P 1 . Part of the line segment L 1  faces the first region R 1  in the first direction D 1 . 
     In other words, on the straight line connecting the central axis C 1  and the upstream boundary position P 1  at which the inner surface of the side wall  33  and the inflow end of the exhaust unit  5  intersect, at least part of the line segment L 1  extending from the outer ends of the blades  42  of the impeller  4  to the boundary position P 1  faces the first region R 1  in the first direction D 1 . 
     Thus, the small distance between the fins  51  in the first region R 1  in which the flow of air is substantially parallel to the direction in which the fins  51  extend may allow the air volume to be adjusted, so that the air volume in the exhaust unit  5  may be made uniform in the direction in which the fins  51  are arrayed. 
       FIG. 4  is a plan view of the air blower  1  with a heat pipe viewed from above illustrating a configuration example thereof. In  FIG. 4 , the lower configuration of a heat pipe  6  is illustrated in transparent view for the sake of convenience. 
     The air blower  1  illustrated in  FIG. 4  includes the heat pipe  6 . The heat pipe  6  extends in the array direction of the fins  51  and is disposed in contact with the upper ends of the plurality of fins  51 . The plurality of fins  51  are held by the heat pipe  6  and the lower plate  32  in the vertical direction. The exhaust unit  5  includes the fins  51 , the heat pipe  6 , and the lower plate  32 . In this case, the fins  51  may be made of metal. The upper plate  31  (not illustrated in  FIG. 4 ) extends to the boundary between the upper plate  31  and the heat pipe  6 . 
     The heat pipe  6  is a component for transferring heat generated from a heat source component  7  to cool the heat source component  7 . An example of the heat source component  7  is a central processing unit (CPU)  8 . An example of the heat pipe  6  is a metal pipe containing a working fluid. The working fluid is evaporated by the heat generated from the heat source component  7 . The evaporated working fluid moves in the heat pipe  6  toward the fins  51  and is cooled by the fins  51  into liquid. At this time, the heat is transferred to the fins  51 . The liquefied working fluid is returned to the heat source component  7  due to capillarity, for example. The returned working fluid is evaporated again, and the operation is circulated. 
     The heat transferred from the heat pipe  6  to the fins  51  is further transferred to the air flowing in the gap between the fins  51 . This allows efficiently cooling the heat source component  7 . The configuration of the heat pipe  6  in  FIG. 4  is given for mere illustrative purposes. For example, the heat pipe  6  may not be in contact with the upper ends of the fins  51  but may be in contact with the lower ends of the fins  51 , or two heat pipes may be individually in contact with the upper ends and the lower ends of the fins  51 . The heat pipe may be in contact with the fins  51  by passing through the fins  51  in the array direction of the fins  51 . The heat pipe  6  may be in contact with the upper plate  31  or the lower plate  32 . In this case, the upper plate  31  or the lower plate  32  may be made of a metal material having thermal conductivity. 
     In other words, the plurality of fins  51  are made of metal, and the air blower  1  includes the heat pipe  6  connected to the plurality of fins  51  along the array of the fins  51 . This allows the heat of the heat pipe  6  to be transferred to the fins  51 , thereby cooling the heat of the heat pipe  6  using the air flowing between the fins  51 . 
     As illustrated in  FIG. 4 , the first region R 1  is disposed at a portion of the heat pipe  6  adjacent to the heat source component  7 . Thus, disposing the first region R 1 , in which air flows at a high speed, at a portion of the heat pipe  6  adjacent to the heat source component  7  allows efficient cooling. 
       FIG. 5  is a diagram illustrating a modification of the configuration of the air blower  1  concerning the distance between the fins  51 . In  FIG. 5 , the direction from the upstream end of the airflow F 1  in the array of the fins  51  toward the line segment extending from the central axis C 1  in the first direction D 1  is represented as a direction D 2 , and the direction from the downstream end of the array of the fins  51  toward the line segment is represented as a direction D 3 . 
     In the air blower  1 , the distance between the fins  51  gradually increases from the upstream end in the direction D 2 , and increases from the downstream end toward the direction D 3 . The air blower  1  illustrated in  FIG. 5  satisfies the condition for the fin distances in the first predetermined distance X and the second predetermined distance Y described above. 
     In other words, the distance between the fins  51  gradually increases from both ends of the array of the fins  51  toward the line segment extending from the central axis C 1  in the first direction D 1 . Thus, finely adjusting the distance between the fins  51  may make the volume of air uniform in the array direction of the fins  51  in the exhaust unit  5 . 
       FIG. 6  is a plan view of an air blower  10  viewed from above illustrating an example in which the present disclosure is applied to a scroll air blower. In  FIG. 6 , the upper plate of a housing  30  is not illustrated. 
     The air blower  10  includes the housing  30 , an impeller  4 , and a motor unit (not illustrated). The impeller  4  and the motor unit are housed in the inner space of the housing  30 . The impeller  4  is centered on the central axis C 1  and has a configuration similar to the configuration of the embodiment described above. The motor unit is disposed inside the impeller  4  and rotates the impeller  4  about the central axis C 1 . 
     The housing  30  includes an upper plate (not illustrated), a lower plate  320 , and a side wall  330 . The lower plate  320  is positioned below the impeller  4  and the motor unit and extends in the radial direction. The motor unit is mounted to the lower plate  320 . The side wall  330  extends upward from the peripheral edge of the lower plate  320 . 
     The side wall  330  includes a curved surface  330 A and flat surfaces  330 B and  330 C. The curved surface  330 A is gradually separated from the central axis C in the rotational direction A 1  of the impeller  4 , as viewed from above. The flat surface  330 B extends linearly from the downstream end of the curved surface  330 A in the tangential direction in top view. The flat surface  330 C extends radially outward from the upstream end of the curved surface  330 A in top view. An air outlet  30 A is formed between the downstream end of the flat surface  330 B and the outer end of the flat surface  330 C. 
     The upper plate (not illustrated) covers the upper opening of an accommodating space formed by the lower plate  320  and the side wall  330 . The upper plate includes an air intake hole (an air intake portion) passing therethrough in the vertical direction. The air intake hole is positioned above the impeller  4 . The air intake hole needs only be provided in at least one of the upper plate and the lower plate  320 . 
     The air outlet  30 A connects to an exhaust unit  50 , which is a separate member from the housing  30 . The exhaust unit  50  includes a plurality of fins  501 . The exhaust unit  50  includes a lower cover and an upper cover that sandwich the fins  501  in the vertical direction. The upper cover is not illustrated in  FIG. 6 . The exhaust unit  50  is disposed in the first direction D 1  with respect to the impeller  4 . 
     When the impeller  4  is rotated in the rotational direction A 1  by the motor unit, air is drawn into the housing  3  through the air intake hole and is blown radially outward between the blades  42  of the impeller  4 . The blown-out air is regulated by the curved surface  330 A and the flat surface  330 B and is discharged through the air outlet  30 A and gaps among the fins  501 .  FIG. 6  illustrates an airflow F 1 , which is the flow of air caused by the rotation of the impeller  4 . 
     As illustrated in  FIG. 6 , it is assumed that the distance from the line segment extending from the central axis C 1  in the first direction D 1  to the array of the fins  501  upstream of the airflow F 1  caused by the rotation of the impeller  4  is a first predetermined distance X. The plurality of fins  501  are located in a first region R 1  located downstream from the first predetermined distance X and in a second region R 2 . 
     The distance between the fins  501  in the first region R 1  is shorter than the distance between the fins  501  in the second region R 2 . In the second region R 2 , the direction of the airflow F 1  is more inclined with respect to the extending direction of the fins  501  than in the first region R 1 . The large fin distance in the second region R 2  may make the air easy to flow through the gap between the fins  501  to thereby increase the volume of air and the amount of exhaust air to be made uniform across the first region R 1  and the second region R 2 . 
     In other words, the air blower  10 , which is a scroll air blower, includes the impeller  4  centered on the central axis C 1  extending in the vertical direction, the motor unit that rotates the impeller  4  about the central axis C 1 , and the housing  30  that houses the impeller  4 . The housing  30  includes the lower plate  320 , which covers the lower side of the impeller  4  and to which the motor unit is fixed, the side wall  330  covering a side of the impeller  4 , and the upper plate covering the upper side of the impeller  4 . At least one of the upper plate and the lower plate  320  includes an air intake portion. The exhaust unit  50  is disposed in the first direction D 1 , which is a radial component of the impeller  4 . The exhaust unit  50  includes the plurality of fins  501 . If the distance from the line segment extending from the central axis C 1  in the first direction D 1  to the array of the fins  501  upstream of the airflow F 1  caused by the rotation of the impeller  4  is the first predetermined distance X, at least part of the plurality of fins  501  are disposed in the first region R 1  located upstream from the first predetermined distance X and in the second region R 2  located downstream from the first region R 1 . The distance between the plurality of fins  501  disposed in the first region R 1  is shorter than the distance between the plurality of fins  501  disposed in the second region R 2 . 
     Thus, increasing the distance between the fins  501  in the second region R 2  in which the airflow F 1  is inclined with respect to the extending direction of the fins  501  may allow the air between the fins  501  to easily flow, thereby decreasing loss in air volume between the fins  501 . This may increase the air flow rate of the air blower  10 . This may also make the air volume in the exhaust unit  50  uniform in the direction in which the fins  501  are arrayed. 
     Although the plurality of fins according to the embodiments of the present disclosure have the same length in the first direction D 1 , this is given for mere illustrative purpose. The plurality of fins may be a combination of fins having different lengths. The axial length of the plurality of fins may also be a combination of different axial lengths on the air inflow side and the air discharge side. 
     While the example embodiments of the present disclosure have been described above, it is to be understood that various modifications of the example embodiments may be made without departing from the spirit and scope of the present disclosure. The present disclosure may be used in, for example, a centrifugal fan air blower.