Patent Publication Number: US-11022137-B2

Title: Fan device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Japanese Patent Application No. 2019-126657, filed Jul. 8, 2019 and Japanese Patent Application No. 2020-001901, filed Jan. 9, 2020, which is hereby incorporated by reference in its entirety. 
     BACKGROUND 
     Technical Field 
     The present disclosure relates to a fan device. 
     Background 
     As a fan device, an axial flow fan is used for a wide range of applications, such as cooling, ventilating, air conditioning, or blowing, in electronic equipment, home appliances, office automation equipment, industrial equipment, and vehicles. For the axial flow fan, for example, a heat radiation structure of a fan is known where a pillow part provided on a fan base forms a ventilation port and a flow path on a side opposite to an impeller boss so that a part of an air flow generated by a fan is introduced into the impeller boss, thus performing heat radiation of the entire motor (see Japanese Patent Laid-Open No. 2006-177309 (patent document 1)). 
     SUMMARY 
     In the fan device, a circuit board is provided in a motor base part on which a motor which rotates the impeller is mounted. Electronic components for forming a control circuit, which controls the operation of the motor, are mounted on the circuit board. In a conventional fan device, the circuit board is mounted in the motor base part such that the circuit board does not protrude outward in the radial direction from the outer periphery of the hub of the impeller so as not to inhibit an air flow generated with the rotation of the impeller. 
     However, in the case where the circuit board is mounted in the motor base part as described above, a sufficient amount of air flow is not introduced into the inside of the motor base part for the circuit board in the conventional fan device. Therefore, in the conventional fan device, when the amount of heat generated from electronic components mounted on the circuit board increases, the heat is confined in the motor base part so that the temperature of the circuit board increases and, as a result, lifespan of the fan device is shortened. 
     Further, in the heat radiation structure of a fan disclosed in patent document 1, the pillow part provided on the fan base, which acts as the motor base part, forms the ventilation port and the flow path on the side opposite to the impeller boss, which acts as the hub. Accordingly a part of an air flow generated with the rotation of the impeller is introduced into the impeller boss, thus performing heat radiation of the motor. 
     However, in the structure disclosed in patent document 1, the outer periphery of the pillow part protrudes outward in the radial direction from the outer periphery of the hub of the impeller. Therefore, in the structure disclosed in patent document 1, when heat radiation of the motor is promoted by increasing the protruding amount of the pillow part, the air flow is inhibited. As a result, the amount of air discharged from a discharge port of a housing is reduced so that fan efficiency is decreased. 
     The present disclosure is related to providing a fan device which can increase fan efficiency while increasing cooling performance for constitutional elements. 
     A fan device includes: an impeller including a hub and a plurality of blades provided on the hub; a motor configured to rotate the impeller; and a housing configured to accommodate the impeller, wherein the housing includes a motor base part which is formed into a cylindrical shape, and which covers the motor from a lower side in a direction of an axis, the motor base part includes a base body part and a base outer peripheral wall part, the base body part being a surface which extends in a radial direction orthogonal to the direction of the axis, and covering the motor from the lower side in the direction of the axis, and the base outer peripheral wall part extending from an end portion of the base body part toward an upper side from the lower side in the direction of the axis, the hub includes a hub body part and a hub outer peripheral wall part, the hub body part being a surface which extends in the radial direction orthogonal to the direction of the axis, and covering the motor from the upper side in the direction of the axis, and the hub outer peripheral wall part extending from an end portion of the hub body part toward the lower side from the upper side in the direction of the axis, and assuming that a diameter of an outer peripheral surface of the hub outer peripheral wall part is “a1”, and a diameter of an outer peripheral surface of the base outer peripheral wall part is “b1”, 1.05&lt;b1/a1&lt;1.13 is established. 
     In the fan device according to one aspect of the present disclosure, a diameter of an inner peripheral surface of the base outer peripheral wall part is greater than the diameter of the outer peripheral surface of the hub outer peripheral wall part over an entire circumference. 
     In the fan device according to one aspect of the present disclosure, the hub body part has an exhaust port which penetrates in the direction of the axis. 
     In the fan device according to one aspect of the present disclosure, a gap part is provided between an inner peripheral surface of the motor base part and an outer peripheral surface of the hub. 
     In the fan device according to one aspect of the present disclosure, the housing includes a first housing and a second housing arranged in the direction of the axis, the first housing has an intake port which is open toward an upper side of the impeller, the second housing has a discharge port which is open toward a lower side of the impeller, and a part of an air flow which flows toward the discharge port from the intake port with rotation of the impeller is introduced into the motor base part from the gap part. 
     According to the fan device of the present disclosure, it is possible to increase fan efficiency while increasing cooling performance for constitutional elements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view schematically showing a configuration of a fan device according to an embodiment of the present disclosure; 
         FIG. 2  is an enlarged cross-sectional view schematically showing the configuration of the fan device shown in  FIG. 1 ; 
         FIG. 3  is a schematic view schematically showing the relationship between diameters of a base outer peripheral wall part of the fan device shown in  FIG. 1  and a diameter of a hub outer peripheral wall part of the fan device shown in  FIG. 1 ; 
         FIG. 4  is an enlarged cross-sectional view schematically showing an air flow in the fan device shown in  FIG. 1 ; 
         FIG. 5  is a graph showing the relationship, in the fan device shown in  FIG. 1 , between a ratio of the outer diameter of a motor base part to the outer diameter of a hub and fan efficiency; and 
         FIG. 6  is an enlarged cross-sectional view schematically showing a configuration of a fan device according to another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, a fan device  1  according to an embodiment of the present disclosure will be described with reference to the accompanying drawings. 
       FIG. 1  is a cross-sectional view schematically showing a configuration of the fan device  1  according to the embodiment of the present disclosure.  FIG. 2  is an enlarged cross-sectional view schematically showing the configuration of the fan device  1  shown in  FIG. 1 . 
     In the description made hereinafter, for the sake of convenience, a direction indicated by an arrow “a” in a direction of an axis x is taken as an upper side “a”, and a direction indicated by an arrow “b” is taken as a lower side “b”. Further, in a radial direction perpendicular to the axis x, a direction away from the axis x (a direction indicated by an arrow “c” in  FIG. 1 ) is taken as an outer peripheral side “c”, and a direction toward the axis x (a direction indicated by an arrow “d” in  FIG. 1 ) is taken as an inner peripheral side “d”. In the description made hereinafter, for the sake of convenience, a side shown in  FIG. 1  is assumed as the side surface of the fan device  1 . Further, in the description made hereinafter, for the sake of convenience, the side of the fan device  1  when the fan device  1  is viewed from the upper side “a” toward the lower side “b” is assumed as a front surface, and a side of the fan device  1  when the fan device  1  is viewed from the lower side “b” toward the upper side “a” is assumed as a bottom surface. 
     As shown in  FIG. 1  and  FIG. 2 , the fan device  1  according to the present embodiment includes a motor  20  which rotates a shaft  15 , an impeller  25  mounted on the shaft  15 , and a housing  10  which accommodates the impeller  25 . The impeller  25  covers the motor  20  from the upper side “a” in the direction of the axis x. The impeller  25  includes a hub  27 , and a plurality of blades  28  provided on the hub  27 . A second housing  12  of the housing  10  includes a motor base part  120  which is formed into a cylindrical shape, and covers the motor  20  from the lower side “b” in the direction of the axis x. The motor base part  120  includes a base body part  121  and a base outer peripheral wall part  124 . The base body part  121  is a surface extending in the radial direction orthogonal to the direction of the axis x, and the base body part  121  covers the motor  20  from the lower side “b” in the direction of the axis x. The base outer peripheral wall part  124  extends from the end portion of the base body part  121  toward the upper side “a” from the lower side “b” in the direction of the axis x. The hub  27  includes a hub body part  272  and a hub outer peripheral wall part  271 . The hub body part  272  is a surface extending in the radial direction orthogonal to the direction of the axis x, and the hub body part  272  covers the motor  20  from the upper side “a” in the direction of an axis c. The hub outer peripheral wall part  271  extends from the end portion of the hub body part  272  toward the lower side “b” from the upper side “a” in the direction of the axis x. Assuming that the outer diameter of the outer peripheral surface of the hub outer peripheral wall part  271  is “a1”, and the outer diameter of the outer peripheral surface of the base outer peripheral wall part  124  is “b1”, 1.05&lt;b1/a1&lt;1.13 is established. Hereinafter, the configuration and the operation of the fan device  1  will be specifically described. 
     [Configuration of Fan Device] 
     The fan device  1  includes, as main constitutional elements, the motor  20 , the impeller  25 , a first housing  11 , and the second housing  12 . 
     The impeller  25  is disposed about the axis x in the first housing  11  and the second housing  12 . The impeller  25  includes the hub  27  having a cup shape, and the plurality of (five, for example) blades  28 . The hub  27  is formed into a cylindrical or a substantially cylindrical shape which is open toward the lower side “b”. The plurality of blades  28  extends in the circumferential direction from the hub outer peripheral wall part  271  provided on the outer peripheral surface of the hub  27 . All blades  28  have the same shape, and are disposed equidistantly in the circumferential direction. The impeller  25  is formed such that the hub  27  and the blades  28  are integrally molded out of a resin. 
     The impeller  25  is caused to adhere to a rotor yoke  40  by an adhesive, for example. The impeller  25  has, on the surface of the hub body part  272  of the hub  27  on the upper side “a”, first exhaust ports  32  which are a plurality of openings penetrating in the direction of the axis x. The rotor yoke  40  has second exhaust ports  41  penetrating in the direction of the axis x at the same position as the first exhaust ports  32  in the radial direction. The first exhaust ports  32  and the second exhaust ports  41  of the fan device  1  form exhaust ports which allow an air flow to flow between the inside and the outside of the impeller  25 . Further, the impeller  25  has an opening part  33  at the center part of the hub body part  272  in the radial direction, and the opening part  33  allows the insertion of a part of a bush  35  which is coupled to the shaft  15 . 
     The rotor yoke  40  may be integrally molded with the impeller  25  by insertion molding. 
     The motor  20  includes a stator  13  attached to the second housing  12  side in a fixed manner, and a rotor  24  attached to the impeller  25  side. 
     The rotor  24  includes the shaft  15 , the rotor yoke  40 , and a magnet  26 . The shaft  15  is provided at the center part of the hub  27  via the bush  35  using the direction of the axis x as a longitudinal direction. The rotor yoke  40  is provided along an inner peripheral surface  27   a  of the hub  27 . The magnet  26  is provided on the inner periphery side “d” of the rotor yoke  40 . The rotor yoke  40  has an insertion hole  43  which allows the insertion of the bush  35  where the shaft  15  is coupled to the center part of the bush  35  in the radial direction. The rotor yoke  40  is swaged and fixed to the bush  35 . 
     The stator  13  mainly includes an insulator  16 , a bearing holder  17 , a stator core  18 , a coil  19 , and bearings  22 . 
     The insulator  16  is mounted on the stator core  18  from both sides, that is, from the upper side “a” and the lower side “b” of the stator core  18  in the direction of the axis. The bearing holder  17  is mounted on a boss part  125  of the second housing  12 . The bearing holder  17  is a member made of metal (for example, brass), and having a hollow cylindrical shape. The bearing holder  17  is mounted on the boss part  125 , made of a resin, by a proper method, such as press fitting. A pair of bearings  22  and a coil spring  23  are mounted in the space of the inner peripheral part of the bearing holder  17 . The pair of bearings  22  rotatably supports the shaft  15 . The coil spring  23  is provided for applying a preload to the bearing  22  on the lower side “b”. 
     The stator core  18  is mounted on the outer periphery of the bearing holder  17 . A circuit board  21  having a donut shape, for example, is attached to the lower side “b” of the stator core  18 . Electronic components are mounted on the circuit board  21 , and the electronic components form a control circuit which controls the operation of the motor  20  of the fan device  1 . The stator core  18  is formed by stacking a plurality of cores made of a soft magnetic material (for example, electromagnetic steel sheet) in the direction of the axis x. The stator core  18  includes a plurality of salient poles extending outward in the radial direction from an annular part. 
     The coil  19  is wound around each salient pole of the stator core  18  via the insulator  16 . The circuit board  21  is attached to the lower side “b” of the insulator  16 . The circuit board  21  is accommodated in the motor base part  120 . 
     The first housing  11  is positioned on the intake side of the fan device  1 , that is, on the upper side “a” in the direction of the axis x. The second housing  12  is positioned on the exhaust side of the fan device  1 , that is, on the lower side “b” in the direction of the axis x. The first housing  11  and the second housing  12  are coupled to form one housing which accommodates the motor  20 , the impeller  25  and the like, which are constitutional elements of the above-mentioned fan device  1 . In the fan device  1 , the housing  10  has a dual structure where the first housing  11  and the second housing  12  are coupled. Therefore, the degree of freedom in shape of the first housing  11  and the second housing  12  can be increased when a complicated shape, for example, the shape of an inner peripheral surface and the shape of fixed wings  123 , is formed by molding using a mold. 
     The first housing  11  is formed to surround the impeller  25  from the outer peripheral side “c”. The first housing  11  includes an intake port  111 , a joint part  112 , and an inner peripheral part  113 . 
     The intake port  111  is open toward the upper side “a” of the impeller  25  to takes air into the impeller  25 . The intake port  111  communicates with the inner peripheral part  113 , and has an inclined surface whose diameter increases from the lower side “b” toward the upper side “a”. The joint part  112  is formed into a shape which can be joined with a joint part of the second housing  12 , which will be described later. As described above, the joint part  112  causes the first housing  11  and the second housing  12  to function as one housing. 
     The inner peripheral part  113  is a peripheral surface of the first housing  11  which faces the impeller  25 . The inner peripheral part  113  has an inclined surface at a portion which faces the intake port  111  side, which is the upper side “a” of the first housing  11 , and the inner peripheral part  113  has an inclined surface at a portion which faces the upper side “a” of the second housing  12 , which is disposed in the vicinity of the joint part  112 , and which will be described later. The portion of the inner peripheral part  113  which faces the upper side “a” of the second housing  12  is formed such that the diameter of the portion continuously formed with the inclined surface increases. 
     The second housing  12  is formed into a shape which surrounds the circuit board  21  from the outer peripheral side “c”. The second housing  12  includes the motor base part  120 , the base body part  121 , a discharge port  122 , the fixed wings  123 , the base outer peripheral wall part  124 , a joint part  126 , an inner peripheral part  127 , and a board accommodating part  128 . 
     The motor base part  120  covers the motor  20  from the lower side “b” in the direction of the axis x. The motor base part  120  includes the base body part  121  and the base outer peripheral wall part  124  having a standing wall shape. The base body part  121  is formed of a surface extending in the radial direction orthogonal to the direction of the axis x. The base outer peripheral wall part  124  is formed to extend from the end portion of the base body part  121  from the lower side “b” toward the upper side “a” in the direction of the axis x. The base body part  121  is formed into a circular shape or a substantially circular shape centered on the axis x. The motor base part  120  is formed into a cylindrical or a substantially cylindrical shape which uses the base body part  121  as a bottom surface, which uses the base outer peripheral wall part  124  as a side surface, and which is open toward the upper side “a”. The motor base part  120  has the board accommodating part  128  on the inner peripheral surface of the motor base part  120  having a cylindrical or a substantially cylindrical shape, and the board accommodating part  128  can accommodate the circuit board  21 . 
       FIG. 2  is an enlarged cross-sectional view schematically showing the configuration of the fan device  1  shown in  FIG. 1 . Further,  FIG. 3  is a schematic view schematically showing the relationship between diameters (an outer diameter b1, an inner diameter b2) of the base outer peripheral wall part  124  of the fan device  1  and the diameter (outer diameter a1) of the hub outer peripheral wall part  271  of the fan device  1 . 
     As shown in  FIG. 2  and  FIG. 3 , the outer diameter b1 of the base outer peripheral wall part  124  of the motor base part  120  is greater than the diameter of the outer peripheral surface of the hub outer peripheral wall part  271  of the hub  27  of the impeller  25 , that is, greater than the outer diameter a1. Further, although the base outer peripheral wall part  124  has a predetermined thickness in the radial direction, the diameter of an inner peripheral part  124   a , that is, the inner diameter b2 is also is greater than the outer diameter a1 of the hub outer peripheral wall part  271 . In the present embodiment, the motor base part  120  and the hub  27  of the impeller  25  are formed into a cylindrical or a substantially cylindrical shape as described above. Therefore, the inner diameter b2 of the base outer peripheral wall part  124  is greater than the outer diameter a1 of the hub outer peripheral wall part  271  over the entire circumference about the axis x. 
     Due to a difference between the outer diameter b1 and the inner diameter b2 of the base outer peripheral wall part  124  and the outer diameter a1 of the hub outer peripheral wall part  271 , the fan device  1  has a gap part G formed between the inner peripheral surface of the base outer peripheral wall part  124  of the motor base part  120  and the hub outer peripheral wall part  271 . As shown in  FIG. 2 , the gap part G is open toward the upper side “a” of the fan device  1 , that is, toward the intake port  111  side. Therefore, a part of the air flow fed toward the discharge port  122  by the blades  28  of the impeller  25  is introduced into the board accommodating part  128  formed on the inner periphery side “d” of the gap part G. 
     The discharge port  122  is open toward the upper side “a” of the impeller  25  to discharge air, taken into the housing  10  from the intake port  111 , to the outside of the fan device  1 . The discharge port  122  communicates with the inner peripheral part  113  of the first housing  11  and the inner peripheral part  127  of the second housing  12 . The joint part  126  is formed into a shape which can be joined with the joint part  112  of the first housing  11  and, as described above, the joint part  126  causes the first housing  11  and the second housing  12  to function as one housing. 
     A plurality of fixed wings  123  are formed on the outer peripheral surface of the motor base part  120 , which is formed into a circular shape or a substantially circular shape, on the discharge port  122  side, which is the lower side “b” of the second housing  12 . The fixed wings  123  extend from the outer peripheral surface of the motor base part  120  toward the outer peripheral side “c” in the radial direction, and are coupled to the inner peripheral part  127  of the second housing  12 . The second housing  12 , the motor base part  120 , and the fixed wings  123  are integrally molded out of a resin. 
     The inner peripheral part  127  is a peripheral surface of the second housing  12  which faces the impeller  25 . The inner diameter of the inner peripheral part  127  is constant in the direction of the axis x. The diameter of the inner peripheral part  127  of the second housing  12  is greater than the diameter of the inner peripheral part  113  of the first housing  11  in which the blades  28  of the impeller  25  rotate. The fan device  1  is configured such that the diameters of the inner peripheral parts  113 ,  127  are increased as a portion progresses from the intake port  111  toward the discharge port  122  to increase a pressure (static pressure). 
     [Operation of Fan Device] 
     Next, the operation of the fan device  1  having the above-described configuration will be described. 
       FIG. 4  is an enlarged cross-sectional view schematically showing an air flow in the fan device  1 . As shown in  FIG. 4 , the motor  20  rotates the rotor  24  against the stator  13 , thus rotationally driving the impeller  25 . When the impeller  25  is rotated by the motor  20 , the plurality of blades  28  provided on the impeller  25  generate an air flow which flows from the intake port  111  of the first housing  11 , which is open toward the upper side “a” of the impeller  25 , toward the discharge port  122 , which is open toward the lower side “b” of the second housing  12 , and which is discharged to the outside through between the fixed wings  123 . 
     The motor base part  120  is formed such that the outer diameter b1 of the motor base part  120  is greater than the outer diameter a1 of the hub outer peripheral wall part  271  of the hub  27  of the impeller  25 . Further, the motor base part  120  is formed such that the inner diameter b2 of the motor base part  120  is greater than the outer diameter a1 of the hub outer peripheral wall part  271  of the hub  27  of the impeller  25 . Therefore, in the fan device  1 , when the impeller  25  is rotated, air flows F 1 , F 2  are caused to pass through between the blades  28 , and are discharged from the discharge port  122 . Of the air flows F 1 , F 2 , a part of the air flow F 2  which flows along the hub outer peripheral wall part  271  is introduced into the board accommodating part  128  of the motor base part  120  from the gap part G. In the fan device  1 , the electronic components mounted on the circuit board  21  are cooled by the air flow F 2  which is introduced into the motor base part  120  so that heat radiation is promoted. 
       FIG. 5  is a graph showing the relationship, in the fan device  1 , between a ratio b1/a1 of the outer diameter b1 of the motor base part  120  to the outer diameter a1 of the hub  27  and fan efficiency E. The fan efficiency E is indicated by a ratio using, as the reference, the fan efficiency E at which the ratio b1/a1 of the outer diameter b1 of the motor base part  120  to the outer diameter a1 of the hub  27  is 1. 
     As shown in  FIG. 5 , when the ratio b1/a1 falls within a range from 1 to 1.05, the fan efficiency E is hardly changed. Whereas, when the ratio b1/a1 becomes 1.05 or more, the fan efficiency E increases and, when the ratio b1/a1 is approximately 1.105, the fan efficiency E reaches the maximum value. After the fan efficiency E reaches the maximum value, the fan efficiency E decreases and, when the ratio b1/a1 becomes approximately 1.13, the fan efficiency E has a value substantially equal to a value before the fan efficiency E is changed, that is, a value at which the ratio b1/a1 is 1 to 1.05. 
     As described above, in the fan device  1 , the range of the ratio b1/a1 which can increase the fan efficiency E is 1.05&lt;b1/a1&lt;1.13. In the fan device  1 , it is preferable to set the ratio to satisfy 1.09&lt;b1/a1&lt;1.12. With such setting, the circuit board  21  can be cooled more, and the fan efficiency E can also be increased. 
     To cause the fan device  1  to have the gap part G for introducing an air flow into the board accommodating part  128  of the motor base part  120 , the inner diameter b2 of the inner peripheral surface of the base outer peripheral wall part  124  of the motor base part  120  is required to be greater than the outer diameter a1 of the hub outer peripheral wall part  271 . Therefore, it is desirable to set the outer diameter b1 of the base outer peripheral wall part  124  by taking into account the thickness (for example, approximately 1 mm) of the base outer peripheral wall part  124 . Depending on a method for molding the motor base part  120 , or mechanical strength of the base outer peripheral wall part  124 , the thickness of the base outer peripheral wall part  124  is not limited to the above-mentioned approximately 1 mm. It is sufficient that the thickness of the base outer peripheral wall part  124  falls within a predetermined numerical range (0.5 to 1.5 mm), for example. Further, it is desirable to set the outer diameter b1 of the base outer peripheral wall part  124  by taking into account the above-mentioned numerical range of the thickness of the base outer peripheral wall part  124 . 
     The fan device  1  has the first exhaust ports  32  and the second exhaust ports  41  as exhaust ports which penetrates in the direction of the axis x between the inside and the outside of the hub  27 . The first exhaust ports  32  are provided in the hub body part  272 . The second exhaust ports  41  are provided in the rotor yoke. The first exhaust ports  32  and the second exhaust ports  41  allow the air flow F 2 , introduced into the board accommodating part  128  of the motor base part  120  from the gap part G, to be discharged to the outside of the hub  27  again while allowing the air flow F 2  to pass through the motor  20  provided in the hub  27 . 
       FIG. 6  is an enlarged cross-sectional view schematically showing the configuration of a fan device  100  according to another embodiment of the present disclosure. As shown in  FIG. 6 , in the case where the hub outer peripheral wall part  271  is formed in an inclined manner to have a tapered shape or the like, the outer diameter a1 of the hub outer peripheral wall part  271  of the hub  27  of the fan device  100  is defined at the lower end of the hub outer peripheral wall part  271 , which is a portion opposing the base outer peripheral wall part  124 . Further, in the case where the base outer peripheral wall part  124  is formed in an inclined manner to have a tapered shape or the like, the outer diameter b1 of the base outer peripheral wall part  124  of the motor base part  120  is defined at the upper end of the base outer peripheral wall part  124 , which is a portion opposing the hub outer peripheral wall part  271 . 
     According to the fan device having the above-mentioned configuration, it is possible to increase fan efficiency while increasing cooling performance for constitutional elements. 
     In addition to the above, those who are skilled in the art may appropriately modify the fan device of the present disclosure according to the conventionally known knowledge. It is needless to say that such modification also falls within the scope of the present disclosure provided that the modification has the configuration of the present disclosure.