Patent Publication Number: US-10781819-B2

Title: Fan device with impeller having circular plate opening, sidewall opening and groove connecting the circular plate opening with the sidewall opening for efficiently cooling motor

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from Japanese Patent Application No. 2015-073858 filed with the Japan Patent Office on Mar. 31, 2015, the entire content of which is hereby incorporated by reference. 
     BACKGROUND 
     1. Technical Field 
     Embodiments of this disclosure relate to an impeller and a fan device that includes the impeller. 
     2. Description of the Related Art 
     Conventionally, a fan device using a motor may damage the motor and a circuit board for the motor and/or deteriorate the performance of the motor due to heat generated from the motor (a stator). In view of this, for the fan device using the motor, restraining the temperature rise of the motor by emitting the heat generated from the motor to the outside has been considered. 
     A fan device was disclosed in JP-A-2008-17607. This fan device has the center through-hole at the center of the impeller and also has the through-hole on the rotor cover. Furthermore, on the back side of the impeller, sub-vanes are provided for introducing outside air. With this fan device, during the rotation of the impeller, the outside air is introduced from the center through-hole by the sub-vanes. The introduced outside air flows through the through-hole on the rotor cover, and ensures cooling the motor. 
     SUMMARY 
     An impeller includes: a cylinder that includes a circular plate-shaped circular plate and a peripheral wall that extends from an outer peripheral edge of the circular plate along a rotation shaft of the impeller; and a blade mounted to an outer peripheral surface of the peripheral wall, the blade being configured to send air. The circular plate has a circular plate opening at a center, the circular plate opening penetrating the circular plate along the rotation shaft, and a sidewall opening is formed at the peripheral wall, the sidewall opening penetrating the peripheral wall along a direction different from a direction parallel to the rotation shaft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating an example of a fan device according to an embodiment of this disclosure; 
         FIG. 2  is an exploded perspective view illustrating an example of the fan device; 
         FIG. 3  is a perspective view illustrating an example of an impeller as viewed from a front side; 
         FIG. 4  is a perspective view illustrating an example of the impeller as viewed from a back side; 
         FIG. 5  is a perspective view illustrating an example of the impeller to which a rotor is mounted as viewed from the back side; 
         FIG. 6  is a cross-sectional explanatory view of the fan device from which a portion A in  FIG. 1  is removed; 
         FIGS. 7A  and B are explanatory views illustrating examples to describe airflow in the fan device; and 
         FIG. 8  is a diagram for describing relationships between airflow volume-static pressure characteristics and a temperature of a motor in the fan device according to the embodiment of this disclosure and a typical fan device. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     In the following detailed description, for purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing. 
     With a fan device, an airflow volume and static pressure have a relationship. Specifically, the fan device has airflow volume-static pressure characteristics in which the static pressure is decreased as the airflow volume becomes larger, and the static pressure is increased as the airflow volume becomes smaller. 
     However, as disclosed in JP-A-2008-17607, in the case where an impeller includes sub-vanes on the back side or the like, as compared with the case where the impeller does not include the sub-vanes on the back side or the like, the airflow volume-static pressure characteristics may be adversely affected. 
     Typically, the static pressure acts on the airflow volume from the actually used fan device. In view of this, the fan device has been requested to more efficiently cool the motor while the static pressure acts. 
     An object of this disclosure is to provide the following impeller and fan device. While restraining a negative effect given to the airflow volume-static pressure characteristics, these impeller and fan device can cool the motor more efficiently in the case where the static pressure acts (is present). 
     An impeller according to an aspect of this disclosure (the present impeller) includes: a cylinder that includes a circular plate-shaped circular plate and a peripheral wall that extends from an outer peripheral edge of the circular plate along a rotation shaft of the impeller; and a blade mounted to an outer peripheral surface of the peripheral wall, the blade being configured to send air. The circular plate has a circular plate opening at a center, the circular plate opening penetrating the circular plate along the rotation shaft, and a sidewall opening is formed at the peripheral wall, the sidewall opening penetrating the peripheral wall along a direction different from a direction parallel to the rotation shaft. 
     A fan device according to an aspect of this disclosure (the present fan device) includes the present impeller and a motor. 
     While restraining the negative effect given to the airflow volume-static pressure characteristics, these impeller and fan device can cool the motor used for the fan device more efficiently in the case where the static pressure acts. 
     The following describes an embodiment according to this disclosure. 
     First, an outline of a fan device  1  according to the embodiment is described with reference to  FIGS. 1 and 2 .  FIG. 1  is a perspective view of the fan device  1 , and  FIG. 2  is an exploded perspective view of the fan device  1 . 
     As illustrated in  FIGS. 1 and 2 , the fan device  1  is a so-called axial fan. The fan device  1  at least includes a rotatable impeller  10 , a motor  20 , and a bracket  30  that surrounds the impeller  10  and the motor  20 . 
     The motor  20  at least includes a rotor  21 , a circuit board  22 , which controls the motor  20  (excitation of coils), and a stator  23 , which is mounted to the circuit board  22  and around which the coils are wound. 
     The rotor  21  has a cylindrical shape, is mounted to an inside of a cylinder  13 , which will be described later, of the impeller  10 , and includes a permanent magnet. The rotor  21  includes a shaft  21   a  (see  FIG. 5 ) that serves as a rotation shaft of the impeller  10 , a circular plate-shaped rotor circular plate  21   b , eight rotor openings  21   c , and four boss holes  21   d . The rotor circular plate  21   b  is a member for mounting the shaft  21   a  to the rotor. The rotor openings  21   c  are disposed on a circular plate  11  (described later) side of the impeller  10  on the rotor  21 . The rotor openings  21   c  penetrate the rotor  21  along the rotation shaft of the impeller  10 . That is, the rotor openings  21   c  penetrate the rotor  21  (for example, a surface approximately vertical to a direction S, which is hereinafter referred to as a “rotation shaft direction S,” of the rotor  21 ) along the rotation shaft direction S parallel to the rotation shaft of the impeller  10 . Bosses  11   b  (see  FIG. 4 ), which will be described later, are inserted into the boss holes  21   d . On the inner peripheral surface side of the rotor  21 , a permanent magnet  21   e  (see  FIG. 5 ) is mounted. 
     The stator  23  is disposed inside the rotor  21 . 
     In this embodiment, the number of the rotor openings  21   c  is eight, and the number of the boss holes  21   d  is four. The numbers of the rotor openings  21   c  and the boss holes  21   d  may be one or may be plural different from this embodiment. Furthermore, without distinction between the rotor openings  21   c  and the boss holes  21   d , five or more (for example, 12) openings into which the four bosses  11   b  are insertable may be disposed. 
     The bracket  30  includes a column-shaped bracket base  31 , a framing body  32 , and a coupler  33 . On the bracket base  31 , the impeller  10 , the rotor  21 , and the circuit board  22  are placed. The framing body  32  forms the outer peripheral surface of the bracket  30 . The coupler  33  couples the framing body  32  and the bracket base  31 . 
     Next, the structure of the impeller  10  according to this embodiment is described with reference to  FIGS. 3 and 4 .  FIG. 3  is a perspective view as viewing the impeller  10  from the front side, and  FIG. 4  is a perspective view as viewing the impeller  10  from the back side. 
     As illustrated in  FIG. 1 , the impeller  10  is used for the fan device  1  with the motor  20 . The impeller  10  includes the cylinder  13  and five blades  14 . The cylinder  13  includes the circular plate-shaped circular plate  11  and a peripheral wall  12 . The peripheral wall  12  extends from the outer peripheral edge (the end edge) of the circular plate  11  along the rotation shaft of the impeller  10 . In other words, the peripheral wall  12  extends from the outer peripheral edge of the circular plate  11  along the rotation shaft direction S of the impeller  10 . The blades  14  are mounted to the outer peripheral surface of the peripheral wall  12 . The blades  14  are members for sending air. 
     On the approximately center of the circular plate  11 , a circular plate opening  15  is formed. The circular plate opening  15  is a circular-shaped opening having a diameter larger than the diameter of the rotor circular plate  21   b . The circular plate opening  15  penetrates the circular plate  11  along the rotation shaft of the impeller  10 . In other words, the circular plate opening  15  penetrates the circular plate  11  (the cylinder  13 ) along the rotation shaft direction S of the impeller  10 . 
     The peripheral wall  12  includes 12 sidewall openings  16 . The sidewall openings  16  penetrate the peripheral wall  12  (the cylinder  13 ) vertically to the rotation shaft direction S of the impeller  10 . 
     In this embodiment, the sidewall openings  16  are formed penetrating the peripheral wall  12  along the direction perpendicular to the rotation shaft direction S of the impeller  10 . The penetrating direction of the sidewall opening  16  is not limited to this direction, and it is only necessary that the penetrating direction differs from the rotation shaft direction S of the impeller  10 . That is, the sidewall opening  16  may penetrate the peripheral wall  12  along the direction different from the rotation shaft direction S. Additionally, the number of the sidewall openings  16  may be one or may be plural different from this embodiment. 
     As illustrated in  FIG. 4 , 12 inductors  11   a  and the four bosses  11   b  are formed on the back side (the back surface side) of the circular plate  11 . The inductors  11   a  are grooves to induce air flowing through the circular plate opening  15  to the sidewall openings  16 . The bosses  11   b  are inserted into boss holes  21   d  (see  FIG. 2 ) of the rotor  21 . 
     In this embodiment, the inductors  11   a  are grooves. Alternatively, as the inductors  11   a , the right and left two walls may be disposed from the circular plate opening  15  to the sidewall openings  16 . 
       FIG. 5  is a perspective view illustrating the impeller  10  to which the rotor  21  is mounted as viewed from the back side. 
     As illustrated in  FIG. 5 , the boss holes  21   d  of the rotor  21  are inserted into the bosses  11   b , which are formed on the back side of the circular plate  11 , to secure the mounting position of the rotor  21  on the impeller  10 . The rotor  21  is adhesively secured to the impeller  10 . The rotation of the rotor  21  also rotates the impeller  10 . 
     The eight rotor openings  21   c  on the rotor  21  allow the air to pass through. The rotor openings  21   c  are positioned facing the inductors  11   a . In other words, when the rotor  21  is mounted to the impeller  10 , the rotor  21  and the impeller  10  are constituted such that at least the one rotor opening  21   c  is disposed at a position facing the inductor  11   a  on the back side of the circular plate  11 . The rotor  21  and the impeller  10  may be constituted such that all the rotor openings  21   c  are disposed at the positions facing the inductors  11   a.    
     In this embodiment, while the number of rotor openings  21   c  is eight, the numbers of the inductors  11   a  and the sidewall openings  16  are 12. Alternatively, the numbers of the rotor openings  21   c , the inductors  11   a , and the sidewall openings  16  may be all the same. 
     Next, the internal structure of the fan device  1  that includes the impeller  10  and the motor  20  is described with reference to  FIG. 6 .  FIG. 6  is a cross-sectional explanatory view of the fan device  1  from which a portion A in  FIG. 1  is removed. 
     As illustrated in  FIG. 6 , the diameter of the circular plate opening  15  is larger than the diameter of the rotor circular plate  21   b . In view of this, the circular plate opening  15  forms a first windway  40  through which outside air is passable. 
     The sidewall opening  16  includes an intake port  16   a  and a discharging port  16   b . The intake port  16   a  takes in the air inside the cylinder  13 . That is, the intake port  16   a  takes in the air from the first windway  40  or the air from the motor  20 . The discharging port  16   b  discharges the air taken from the intake port  16   a  to the outside of the cylinder  13 . 
     Here, the discharging port  16   b  is formed on the circular plate  11  side with respect to an installation surface of the peripheral wall  12  to which the blades  14  are mounted. Thus, the air discharged from the discharging port  16   b  is sent by the blades  14 . 
     Between the cylinder  13  and the bracket base  31 , a second windway  41  through which the outside air is passable is formed. 
     In view of this, the fan device  1  is constituted such that the air flows to the motor  20  via the first windway  40 , the second windway  41 , and the rotor openings  21   c . Accordingly, the motor  20  can be cooled down. 
     Next, the airflow in the fan device  1  according to this embodiment is described with reference to  FIGS. 7A and 7B .  FIGS. 7A and 7B  are explanatory views to describe the airflow in the fan device  1 , and are cross-sectional views corresponding to  FIG. 6 .  FIG. 7A  is an explanatory view to describe the airflow in the fan device  1  when the static pressure does not act (the static pressure is approximately zero, during a so-called free air).  FIG. 7B  is an explanatory view to describe the airflow in the fan device  1  when the static pressure acts. 
     As illustrated in  FIG. 7A , when the static pressure does not act, the blades  14  cause the air to flow along an inclined direction F 0 , which is slightly inclined to the outside of the blades  14  almost approximately parallel to the rotation shaft direction S of the impeller  10 . The magnitude of the inclination of the inclined direction F 0  (for example, the inclination to the rotation shaft direction S) changes depending on the shape of the blades  14  and the like. 
     This high-speed flow of the air by the blades  14  along the inclined direction F 0  lowers a pressure P 1  near the discharging port  16   b , as compared with a pressure P 0  near the first windway  40 . Accordingly, as indicated by an arrow K 1 , the air flows from the first windway  40  to the discharging port  16   b.    
     A pressure P 2  near the second windway  41  has a value approximately identical to the pressure P 1  near the discharging port  16   b . In view of this, the pressure P 2  is lower than the pressure P 0  near the first windway  40 . Therefore, as indicated by an arrow K 2 , the air taken from the first windway  40  flows to the motor  20  via the rotor openings  21   c . Furthermore, as indicated by an arrow K 3 , the air inside the motor  20  flows to the second windway  41 . 
     As illustrated in  FIG. 7B , while the static pressure acts, the blades  14  cause the air to flow along an inclined direction F 1 , which is largely inclined to the outside of the blades  14  with respect to the rotation shaft direction S of the impeller  10 . The magnitude of the inclination of the inclined direction F 1  (for example, the inclination with respect to the rotation shaft direction S) changes depending on the shape of the blades  14 , the magnitude of the static pressure, and the like. 
     Similarly to  FIG. 7A , the pressure P 1  near the discharging port  16   b  is lower than the pressure P 0  near the first windway  40 . In view of this, as indicated by the arrow K 1 , the air taken from the first windway  40  flows to the discharging port  16   b.    
     Unlike  FIG. 7A , the flow rate of air by the blades  14  near the second windway  41  is slower than the flow rate of air by the blades  14  near the discharging port  16   b . Accordingly, the pressure P 2  near the second windway  41  is higher than the pressure P 1  near the discharging port  16   b . In view of this, as indicated by an arrow K 4 , the air flows from the second windway  41  to the discharging port  16   b.    
     The pressure P 2  near the second windway  41  is lower than the pressure P 0  near the first windway  40 . According to a pressure difference between the pressure P 1  near the discharging port  16   b  and the pressure P 2  near the second windway  41 , and a pressure difference between the pressure P 1  near the discharging port  16   b  and the pressure P 0  near the first windway  40 , as indicated by an arrow K 5 , the air inside the motor  20  flows to the discharging port  16   b  and the air taken from the first windway  40  flows to the rotor openings  21   c.    
     The above-described fan device  1  according to this embodiment and the typical fan device are hereinafter compared to each other. 
       FIG. 8  illustrates relationships between the airflow volume-static pressure characteristics and the temperature characteristics of the motor in the fan device  1  according to the embodiment and the typical fan device. In  FIG. 8 , the left vertical axis indicates the static pressure (Static Pressure), the lower horizontal axis indicates the airflow volume (Air Flow), and the right vertical axis indicates the temperature (temperature) of the motor (a winding wire wound around the stator). The solid lines indicate the properties of the typical fan device while the one dot chain lines indicate the properties of the fan device  1  according to the embodiment. The upper solid line indicates the temperature characteristics of the motor in the typical fan device. The upper one dot chain line indicates the temperature characteristics of the motor in the fan device  1 . The lower solid line indicates the airflow volume-static pressure characteristics in the typical fan device. The lower one dot chain line indicates the airflow volume-static pressure characteristics in the fan device  1 . 
     Here, the typical fan device is a fan device that does not include the sidewall openings  16 . In the measurements related to  FIG. 8 , as the typical fan device, the fan device  1  whose sidewall openings  16  are experimentally obstructed is used (see  FIG. 3  and the like). 
     The temperature characteristics of the motor, which are shown on the upper side in  FIG. 8 , are the temperature characteristics of the motor when the static pressure acts (the static pressure: within the range of about 100 to about 1600, the airflow volume: within the range of 0 to about 16). As illustrated in this drawing, it has been found that the fan device  1  according to this embodiment was able to cool the motor low up to 8 K, as compared with the typical fan device. 
     According to the airflow volume-static pressure characteristics on the lower side in  FIG. 8 , the shapes of the airflow volume-static pressure characteristics mostly match between the fan device  1  according to this embodiment and the typical fan device. In view of this, it has been found that, with the fan device  1  of this embodiment, the sidewall openings  16  do not adversely affect the airflow volume-static pressure characteristics as compared with the typical fan device. 
     As described above, while the fan device  1  according to this embodiment restrains adversely affecting the airflow volume-static pressure characteristics, the fan device  1  ensures cooling the motor used for the fan device more efficiently when the static pressure acts. 
     In this embodiment, the inductors  11   a  are formed on the back side of the circular plate  11 . Alternatively, the impeller  10  and the fan device  1  of this embodiment may not include the inductors  11   a.    
     In this embodiment, the fan device  1  includes at least the one rotor opening  21   c  disposed at the position facing the inductor  11   a . Alternatively, the fan device  1  may be constituted such that the all rotor openings  21   c  are disposed at positions not facing the inductors  11   a.    
     In this embodiment, the fan device  1  is an axial fan that includes one impeller. Alternatively, the fan device  1  may be a multiplexed (duplex) inverting axial fan where a plurality of (two) impellers are directly disposed. In this case, among the plurality of impellers, at least one impeller may be the impeller  10  according to this embodiment. 
     The embodiment of this disclosure may be any of the following first to third impellers and first to third fan devices. 
     The first impeller is an impeller used for a fan device with a motor. The impeller includes a cylinder and a blade. The cylinder forms a circular plate-shaped circular plate and a peripheral wall. The peripheral wall extends from an outer peripheral edge of the circular plate parallel to a rotation shaft of the impeller. The blade is mounted to an outer peripheral surface of the peripheral wall. The blade is configured to send air. The circular plate forms a circular plate opening at a center. The circular plate opening penetrates parallel to the rotation shaft. At the peripheral wall, a sidewall opening is formed. The sidewall opening penetrates in a direction different from the direction parallel to the rotation shaft. 
     The second impeller according to the first impeller is configured as follows. The circular plate forms an inductor on a back surface side. The inductor is configured to induce air flowing through the circular plate opening to the sidewall opening. 
     The third impeller according to the first or the second impeller is configured as follows. The sidewall opening forms an intake port and a discharging port on the peripheral wall. The intake port is configured to take in air inside the cylinder. The discharging port is configured to discharge the air taken from the intake port to outside of the cylinder. The discharging port is formed on the circular plate side with respect to an installation surface of the peripheral wall to which the blade is mounted. 
     The first fan device is a fan device with an impeller and a motor. The impeller includes a cylinder and a blade. The cylinder includes a circular plate-shaped circular plate and has a peripheral wall. The peripheral wall extends from an end edge of the circular plate parallel to a rotation shaft of an impeller. The blade is mounted to an outer peripheral surface of the peripheral wall. The blade is configured to send air. The circular plate has a circular plate opening at a center. The circular plate opening penetrates parallel to the rotation shaft. At the peripheral wall, a sidewall opening is formed. The sidewall opening penetrates in a direction different from the direction parallel to the rotation shaft. 
     The second fan device according to the first fan device is configured as follows. The motor at least includes a cylindrical-shaped rotor and a stator. The rotor is mounted to an inside of the cylinder on the impeller. The rotor includes a permanent magnet. The stator is disposed inside the rotor. The rotor opening is formed on the circular plate side of the rotor. The rotor opening penetrates parallel to the rotation shaft. 
     The third fan device according to the second fan device is configured as follows. The impeller forms an inductor on a back surface side of the circular plate. The inductor is configured to induce air flowing through the circular plate opening to the sidewall opening. The rotor opening of the motor is disposed at a position facing the inductor when the rotor is mounted to an inside of the impeller. 
     According to the first to the third impellers and the first to the third fan devices, the motor used for the fan device can be more efficiently cooled without giving a negative effect to the airflow volume-static pressure characteristics in the case where the static pressure acts. 
     The foregoing detailed description has been presented for the purposes of illustration and description. Many modifications and variations are possible in light of the above teaching. It is not intended to be exhaustive or to limit the subject matter described herein to the precise form disclosed. Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims appended hereto.