Abstract:
The disclosure aims to provide a ventilator module with improved efficiency. The ventilator module employs the dual structure of fans includes a swirler fan and a suction fan, in which the swirler fan is disposed at the front side and the suction fan is disposed at the rear side of the swirler fan so that a swirl formed by the drive of the swirler fan forms a donut-like low pressure zone around an inlet, and a tornado is formed by rotating the donut-like low pressure zone by the drive of the suction fan thereby cause the air below swirler fan to ascend at high velocity so as to be suctioned and discharged.

Description:
[0001]    The present application claims priority from Korean Patent Application No. 2014-0175073, filed on Dec. 8, 2014, which is hereby incorporated by reference for all purposes as if fully set forth herein. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    The disclosure relates to a ventilation system, more particularly to a ventilation apparatus employing a swirler fan formed with plural fins on an annular disk with the opening at the center portion to improve efficiency. 
         [0004]    2. Description of Related Art 
         [0005]    Air moves from high atmospheric pressure region to low atmospheric pressure region. The mechanical fans are utilizing this aerodynamic principle. Rotating blades pushes air outwards and thereby the atmospheric pressures around the blades are lowered. Then air in surroundings in relatively high atmospheric pressure moves toward the blades. By the directions of blades&#39; distortion, air is suctioned or discharged. 
         [0006]    A ventilation fan is used to eliminate contaminants (gases, dusts or particles) in a certain space. A range hood for kitchen made of a ventilation fan is used to discharge pollutants and food odors generated during cooking to the outside by driving a fan so as to prevent them to be dispersed to other space. And a portable dust collector or a portable welding fume extractor made of a ventilation fan is used to eliminate dusts, oil mist, fume, etc. generated in local work places. 
         [0007]    In general, a ventilation fan is configured to install pipes in the walls or on the ceilings and to dispose an exhaust vent to the outside, and further, to install an exhaust fan adjacent to an exhaust vent, disposed at the front side of the pipe or the rear side of the pipe. Here, a centrifugal fan (a sirocco fan or a turbo fan) is most commonly used for the exhaust fan to be installed, and infrequently, an axial propeller fan is used. 
         [0008]    A ventilation fan is based on the assumption that a fan generates the negative pressures and makes airflow movements toward an exhaust inlet, then contaminants in the space will be carried out with the air exhausted. However, to carry out contaminants to the exhaust in the presence of distributing side flows, gravitational settling, and inertial breakaways of contaminants themselves, the fan has to generate high enough air velocity at the position in which contaminants exist. It is the capture velocity. The minimum capture velocity in quiet air is 50 fpm (0.25 m/s) according to “ACGIH Industrial ventilation: A manual of recommended Practice, 23 th  edition”. It means that in case the air velocity generated by a ventilation fan is lower than the minimum capture velocity, the contaminants can&#39;t be carried out with the air but just light air are exhausted. 
         [0009]    Such a ventilation fan of the related art is disadvantageous in that the capture region of contaminants is only defined at the part adjacent to an inlet as illustrated in the diagram of simulation of  FIG. 1 . That is, when using the exhaust fan configured in a manner such that a plurality of projected blades are arranged at a predetermined interval on a cylindrical body, the air velocity suctioned rapidly decreases inversely proportional to the square of a distance from the entrance of the exhaust vent. Due to such a property, the suction power rapidly drops unless the exhaust fan is installed to be adjacent to a source to generate contaminants. 
         [0010]    As illustrated in  FIG. 2  (velocity Contours—plain circular opening— % of opening velocity; American Conference of Governmental Industrial Hygienists (ACGIH): Industrial Ventilation Manual, 23rd Edition), this is because that, although the rotation of a typical exhaust fan generates an ascending air current, the velocity of the air current at a position dropped as much as the diameter of the entrance of the exhaust vent is reduced to about 7.4% of the air velocity at the entrance of the exhaust vent. 
         [0011]    Such a phenomenon that the velocity is reduced inversely proportional to the square of a distance from the entrance of the exhaust vent is well-known as Dalle Valle equation. Dalla Valle Equation is, 
         [0000]    
       
         
           
             Vx 
             = 
             
               Vf 
               
                 
                   12.7 
                   × 
                   
                     
                       ( 
                       
                         x 
                         d 
                       
                       ) 
                     
                     2 
                   
                 
                 + 
                 0.75 
               
             
           
         
       
     
         [0000]    Where Vx is velocity at x 
         [0012]    Vf is a face velocity at the exhaust inlet
       x is a distance from the exhaust inlet       
 
         [0014]    d is a diameter of exhaust inlet. 
         [0015]    For the velocity x=1d 
         [0000]    
       
         
           
             
               Vx 
               = 
               
                 
                   Vf 
                   
                     
                       12.7 
                       × 
                       
                         
                           ( 
                           
                             1 
                             1 
                           
                           ) 
                         
                         2 
                       
                     
                     + 
                     0.75 
                   
                 
                 = 
                 
                   
                     Vf 
                     13.45 
                   
                   = 
                   
                     0.074 
                      
                     
                         
                     
                      
                     Vf 
                   
                 
               
             
             , 
           
         
       
     
         [0000]    Consequently, the velocity at x=1d, decreases to 7.4% of the face velocity at the exhaust inlet. 
         [0016]    Regardless of such a mechanism, in the configuration of the ventilation fan, the exhaust vent is positioned at a point away from the contaminant&#39;s source farther than the diameter of the entrance of the exhaust vent so that the discharge power thereof is extremely low. Accordingly, all the existing exhaust apparatuses including a range hood attempt to increase the discharge power by increasing exhaust air volume to raise the air velocity. 
         [0017]    However, according to Fan Affinity Law, in order to double the air velocity, it is necessary to increase the power consumption of a fan by 2 3 , that is, eight times (cubic law of air velocity), which is problematic because the power consumption becomes too great and accordingly, the noise thus caused increases. 
         [0018]    Power consumption of centrifugal fan by Fan Affinity Law is, 
         [0000]        P   1   /P   2 =( n   1   /n   2 ) 3 ( d   1   /d   2 ) 5   , q   1   /q   2 =( n   1   /n   2 )( d   1   /d   2 ) 3    
         [0019]    where 
         [0020]    P=power (W, bhp, . . . ) 
         [0021]    q=volume flow capacity (m 3 /s, gpm, cfm, . . . ) 
         [0022]    n=wheel velocity-revolution per minute-(rpm) 
         [0023]    d=wheel diameter 
       SUMMARY 
       [0024]    Accordingly, the object of the disclosure is to provide a ventilator module of a new scheme capable of improving discharge power while reducing both power consumption and noise. 
         [0025]    According to the object described above, a ventilator module of the disclosure is configured to employ dual structure of fans. The ventilator module includes a swirler fan and a suction fan and the swirler fan formed with plural fins on an annular disk with the opening at the center portion is disposed at the front side and the suction fan is disposed at the rear side of the swirler fan so as to form a donut-like low pressure zone around an inlet by a swirl formed by the drive of the swirler fan so that the air at the lower part, which forms a relatively high pressure zone, ascends at a high velocity, and then, is suctioned to an exhaust vent to be discharged by the drive of the suction fan. 
         [0026]    In addition, according to the disclosure the ventilator module configured in a manner such that a bell-mouth that is disposed to surround the swirler fan and is formed as a quadrangular truncated pyramid or a truncated cone with a horizontal end formed at the bottom thereof so as to widen the formation area of the donut-like low pressure zone thereby effectively enlarging the capture region of pollutants. 
         [0027]    In other words, according to an aspect of the disclosure, provided is a ventilator module including: 
         [0028]    a swirler fan formed with plural fins on an annular disk with the opening at the center portion thereof; 
         [0029]    a suction fan disposed at the rear side of the swirler fan; 
         [0030]    a motor that is assembled via mounting fixtures to the housing so as to be coupled on the same axis and to simultaneously drive the swirler fan and the suction fan; 
         [0031]    a bell-mouth that surrounds the swirler fan and is formed as a truncated pyramid, an elliptical truncated cone or a truncated cone with an opening formed at the top thereof and a horizontal end formed at the bottom thereof; and 
         [0032]    an suction fan case that accommodates the suction fan therein, in which an opening is provided in the bottom of a part in which the suction fan is accommodated, and of which the top is assembled with an outlet. 
         [0033]    In addition, according to an aspect of the disclosure, provided is the ventilator module further includes a suction fan case having an opening at a bottom surface thereof and an outlet assembled with the suction fan case. 
         [0034]    In addition, according to an aspect of the disclosure, the swirler fan includes a center which is connected to the axis of the motor, an annular band which surrounds outside of the center, a plurality of connection rods which extends from outer surface of the center to inner surface of the annular band in a radial direction, and a ring-shape main body which surrounds outer surface of the annular band on which a plurality of fins is formed. 
         [0035]    In addition, according to an aspect of the disclosure, provided is the ventilator module further includes a grid-like guard below the swirler fan. 
         [0036]    In addition, according to an aspect of the disclosure, the swirler fan includes a center which is connected to the axis of the motor, a ring-shape main body which is combined with the center, an annular band which surrounds outside of the ring-shape main body and has a plurality of fins protruded toward outside of the annular band along outer surface of the annular band, and a plurality of connection rods which extends from outer surface of the ring-shape main body to inner surface of the annular band in a radial direction. 
         [0037]    In addition, according to an aspect of the disclosure, the swirler fan has auxiliary blades on the connection rods to increase the suction air velocity. 
         [0038]    In addition, according to an aspect of the disclosure, provided is the ventilator module, in which the suction fan disposed at the rear side of the swirler fan is configured as an axial propeller fan, and an outlet of a suction fan case is assembled so as to be on the same axis as a point at which the suction fan is disposed. 
         [0039]    In addition, according to an aspect of the disclosure, provided is the ventilator module including; 
         [0040]    a swirler fan formed with plural fins on an annular disk with the opening at the center portion thereof; 
         [0041]    a motor housing with mounting fixtures to accommodate the swirler fan therein. 
         [0042]    a motor that is assembled via mounting fixtures to the motor housing so as to drive the swirler fan; 
         [0043]    a suction fan disposed separately with distance at the rear side of the swirler fan; 
         [0044]    a suction fan case with mounting fixtures to accommodate the suction fan therein. 
         [0045]    a motor that is assembled via mounting fixtures to the suction fan case so as to drive the suction fan independently. 
         [0046]    According to the disclosure, it is possible to provide a exhaust fan or a range hood or a portable dust collector that exhibits strong suction and discharge power by forming an extremely strong tornado air current due to a dual stage fans of a ventilator module that suctions air at high velocity in the ventilation apparatuses. That is, a swirl generated by a swirler fan forms a donut-like low pressure zone so that the air at the lower part, which forms a relatively high pressure zone, ascends at a high velocity, and the air adjacent to the swirler fan is strongly suctioned and discharged by the drive of the suction fan. 
         [0047]    In this aerodynamic mechanism, some portion of inducing air via the opening at the center of the swirler fan can be re-diffused to the direction of circumference due to the air forces pushing outward by the rotation of fins on the annular disk. An annular band with a certain height erected vertically in between the inner side of the planer ring-shape main body and the connection rods to the center does a role of preventing inducing air via the opening at the center of the swirler fan from re-diffusing to the direction of circumference, and exhausting efficiently to the outlet. 
         [0048]    According to the ventilator module of the disclosure, compared to a ventilation fan by a sirocco fan of the related art, it is possible to exhibit the suction and discharge power over the greater wide range of area, and to eliminate pollutants and odors speedily due to the high velocity of the ascending air current. 
         [0049]    In addition, a bell-mouth according to the disclosure may induce the formation of the donut-like low pressure zone over the more extended range at the periphery of the swirler fan so as to enlarge and maintain the center portion of the tornado air current thereby widening the generation area of the ascending air current. 
         [0050]    According to the ventilator module of the disclosure employing the dual structure of fans and the bell-mouth, it is possible to powerfully and speedily discharge pollutants and odors in the space with a relatively low power and little noise because it doesn&#39;t need to increase wasteful airflow rate to increase air velocity as the conventional fans of the related art do. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0051]      FIG. 1  is a diagram that illustrates the result of simulation of air current and pressure contours according to a conventional exhaust apparatus of the related art. 
           [0052]      FIG. 2  is a diagram that illustrates velocity contours at an inlet of a typical exhaust vent on “velocity Contours—plain circular opening— % of opening velocity; American Conference of Governmental Industrial Hygienists (ACGIH): Industrial Ventilation Manual, 23rd Edition”. 
           [0053]      FIG. 3  is an exploded perspective view that illustrates a configuration of a ventilator module according to the disclosure. 
           [0054]      FIG. 4  is a cut exploded perspective view of the range hood configured with the ventilator module according to the disclosure. 
           [0055]      FIG. 5  is a perspective view of the swirler fan according to the disclosure. 
           [0056]      FIG. 6  is a perspective view that illustrates another example of the swirler fan according to the disclosure. 
           [0057]      FIG. 7  is a perspective view that illustrates an assembly of the ventilator module according to the disclosure. 
           [0058]      FIG. 8  is an exploded perspective view that illustrates another example of the ventilator module according to the disclosure. 
           [0059]      FIG. 9  is an exploded perspective view that illustrates another configuration of a ventilator module according to the disclosure. 
           [0060]      FIG. 10  is a diagram that illustrates the result of simulation of air current and pressure contours formed by the ventilator module according to the disclosure. 
           [0061]      FIG. 11  is a diagram that illustrates the capture region by the result of simulation of air current and velocity contours formed by the ventilator module according to the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0062]    Hereinafter, preferred embodiments of the disclosure will be described in detail, with reference to the attached drawings. 
         [0063]      FIG. 3  is an exploded perspective view that illustrates a configuration of a ventilator module according to the disclosure. 
         [0064]    A ventilator module according to the present exemplary embodiment includes a swirler fan  100 , a suction fan  200 , and a motor  300 . The ventilator module may further include a suction fan case  400 , a bell-mouth  500 , an outlet  600  and a housing  700 . 
         [0065]    A swirler fan  100  provided with an opening  107  at the center thereof, and an suction fan  200  arranged at the rear side of the swirler fan  100  are coupled with one motor  300  via coupling members so as to be simultaneously driven. The two fans are assembled to be coupled with the motor  300  being maintained on the same axis which is an axis  330  of the motor. 
         [0066]      FIG. 4  is a cut exploded perspective view of the range hood configured with the ventilator module according to the disclosure. 
         [0067]    In general, the range hood is installed on the ceiling of kitchen, and thus, a hood body  710  may be installed on the ceiling so as to serve as a support body for various members to be fixed to the ceiling, and improve the aesthetics. The hood body  710  is provided with an opening at the center thereof. The bell-mouth  500  and the swirler fan  100  are disposed at the front side of the hood body  710 . The suction fan case  400  which receives the suction fan  200 , and the outlet  600  are disposed in the rear side of the hood body. 
         [0068]    In addition, it is desirable to install a grid-like guard  800  below the swirler fan  100 . 
         [0069]    In this case, the housing  700  having a hexahedron shape to form a space therein may be combined with the rear side of the hood body  710 . The suction fan case  400  is received in the space of the housing  700 , and the motor  300  and the outlet  600  are disposed at a rear side of the housing  700  to be connected to the suction fan case  400 . 
         [0070]      FIG. 5  is a perspective view of the swirler fan according to the disclosure. 
         [0071]    The swirler fan  100  is configured such that a plurality of fins  104  are arranged toward the bottom of a main body at the lower side of the planer ring-shape main body  102  having an opened center portion, and a central opening  107  is provided with connection rods  106  to form a connection so that a shaft of the motor  300  is connected to the center, and an annular band  108  with a certain height is erected vertically in between the inner side of the planer ring-shape main body  102  and the connection rods  106  to the center  100   a  thereof. 
         [0072]    Thus, the swirler fan  100  of  FIG. 5  includes a center  100   a  which is connected to the axis  330  of the motor  300 , an annular band  108  which surrounds outside of the center  100   a , a plurality of connection rods  106  which extends from outer surface of the center  100   a  to inner surface of the annular band  108  in a radial direction, and a ring-shape main body  102  which surrounds outer surface of the annular band  108  on which a plurality of fins  104  is formed. 
         [0073]    In this case, an auxiliary blade  101  with a predetermined slant angle may be formed at a side of the connection rod  106 . The auxiliary blade  101  may increase flow speed through the opening  107  when the ring-shape main body  102  rotates. 
         [0074]      FIG. 6  is a perspective view that illustrates another example of the swirler fan according to the disclosure. 
         [0075]    the swirler fan  100  is configured such that a plurality of connection rods  106  are arranged from the center, and an annular band  108  with a certain height is erected at the end of the connection rods  106 , and a plurality of fins  104  are formed at the outer side of the annular band  108  thereof. 
         [0076]    Thus, the swirler fan  100  of  FIG. 5  includes a center  100   a  which is connected to the axis  330  of the motor  300 , a ring-shape main body  102  which is combined with the center  100   a , an annular band  108  which surrounds outside of the ring-shape main body  102  and has a plurality of fins protruded toward outside of the annular band  108  along outer surface of the annular band  108 , and a plurality of connection rods  106  which extends from outer surface of the ring-shape main body  102  to inner surface of the annular band  108  in a radial direction. 
         [0077]    In addition, an auxiliary blade  101  with a predetermined slant angle may be formed at a side of the connection rod  106 . The auxiliary blade  101  may increase suction air velocity through the opening  107  when the ring-shape main body  102  rotates. 
         [0078]    In addition, according to another example embodiment of the disclosure, an end of a connection rod  106  may penetrate an annular band  108  to be protruded toward outside, and a fin  104  may be formed on the end of the connection rod  106  in a perpendicular direction. In another example embodiment, the fin  104  may include a horizontal element which is formed on outer surface of the annular band  108  in parallel with the ring-shape main body  102 , and a vertical element which is formed at an end of the horizontal element in perpendicular direction. 
         [0079]    The swirler fan  100  is rotated by the motor  300  to form a swirl. The swirl forms, as illustrated in  FIGS. 10 and 11 , a donut-like low pressure zone.  FIGS. 10 and 11  are exemplary cross-sectional views. When the swirler fan  100  is driven, the air current flows toward the outer side of the swirler fan  100  and then flows back toward the center of the swirler fan  100  thereby forming a low pressure trough. That is, a donut-like (viewed in three dimensions) low pressure zone is formed at the outer side periphery of the swirler fan  100 . Due to the low pressure zone, low pressure is also formed around the center portion of the swirler fan  100  so that an ascending air current is generated for a while. However, only with the low pressure formed at the center portion by the swirler fan  100 , it is difficult to obtain a desired level of effect in air suction and discharge. Therefore, according to the disclosure, the suction fan  200  is additionally provided at the rear side of the swirler fan  100  and driven so as to generate a stronger ascending air current. When the suction fan  200  and the swirler fan  100  are driven to rotate together, the donut-like low pressure zone takes a circular motion to form a tornado air current that allows a wide range of collection of air. A significantly strong level of low pressure zone is formed at the center portion of the tornado air current so that the air current ascend at high speed by receiving rising propulsion supplied by the suction fan  200 . With such a mechanism, the ventilator module according to the disclosure can exhibit powerful and speedy discharge effect of pollutants and odors. 
         [0080]    The swirler fan  100  and the suction fan  200  are assembled on the same axis, and the one motor  300  is coupled thereto at the axis so as to drive the swirler fan  100  and the suction fan  200  simultaneously. 
         [0081]    The bell-mouth  500  having an opening  520  at an upper portion thereof and an inclined surface which is inclined toward outside and bottom direction along boundaries of the upper portion, as illustrated in  FIG. 3 ,  FIG. 4 , is provided with a horizontal end  510 , expanded in horizontal, at an end of the inclined surface of the bell-mouth  500  which is the bottom of the bell-mouth  500 . With such a horizontal end  510 , as can be seen from the simulation of  FIG. 10 , the air current generated by the drive of the swirler fan  100  forms a swirl along the horizontal end  510  thereby enlarging the size of the swirl according to Coanda Effect, which is the tendency of a fluid jet to be attracted to a nearby surface, and as a result, the collection area increases. 
         [0082]    In other words, as the air current flows along an inclined surface of the bell-mouth  500  and the horizontal end  510 , the travel distance of the air current is extended so that the air current flows back rather than receives a constant propulsion thereby forming the donut-like low pressure zone. It is satisfactory that such a bell-mouth  500  has the inclined surface and the horizontal end  510 , and thus, the shape thereof is not necessarily the quadrangular truncated pyramid. When the bell-mouth  500  is formed as a truncated pyramid, an elliptical truncated cone or a truncated cone and the bottom thereof is provided with the horizontal end  510 , it is possible to exhibit the same function. In case of the quadrangular truncated pyramid shape, the horizontal end  510  is provided only at an edge in the lateral direction to simplify the configuration. 
         [0083]    The bell-mouth  500  also has an opening  520  at the center portion. With the opening  520 , it is possible to increase the flow rate of ascending air current at the center portion and to extend the collection range. 
         [0084]    When the donut-like low pressure zone is formed according to the configuration of the swirler fan  100  and the bell-mouth  500 , it is necessary to apply a driving force to rotate the low pressure zone to form a tornado air current so that a strong ascending air current is formed at the center thereof, which is served by the suction fan  200 . As the suction fan  200 , a conventionally well-known centrifugal fan (a sirocco fan or a turbo fan) or an axial fan may be applied, and also as a suction fan case  400 , a conventionally well-known case is used. The suction fan is a cylinder with an opening  220  at the center thereof and has a plurality of blades  210 . The suction fan case  400  as described in  FIG. 3  includes a part in which the suction fan  200  is accommodated and a part into which an outlet  600  is assembled, which are configured to be eccentric to each other. In the bottom of the suction fan case  400 , an opening  420  is provided at the part in which the suction fan  200  is accommodated, and in the top of the suction fan case  400 , an opening is provided at the part into which the outlet  600  is assembled. Other than the suction fan case  400 , a housing  700  that accommodates the suction fan case  400  therein may be further applied, and accordingly, the top of the suction fan case  400  may be completely opened. In this case, the top of the suction fan case  400  is assembled to the housing  700 , the suction fan case  400  is accommodated in the housing  700  in a manner such that the housing  700  completely seals the air current. This embodiment adopts such a configuration as illustrated in the drawings. 
         [0085]      FIG. 7  is a perspective view that illustrates an assembly of the ventilator module according to the disclosure. 
         [0086]    The motor  300  is combined with a rear end of the suction fan case  400 . The suction fan  200  is received in the suction fan case  400 . The housing  700  and the bell-mouth  500  are combined with a front end of the suction fan case  400  in order. The axis  330  of the motor  300  penetrates the opening  420  of the suction fan case  400 , the suction fan  200 , the opening  720  of the housing  700 , and the opening  520  of the bell-mouth  500 , so that the axis  330  is combined with the center  100   a  of the swirler fan  100 . The outlet  600  is formed toward outside of the suction fan  200  in a radial direction. 
         [0087]      FIG. 8  is an exploded perspective view that illustrates another example of the ventilator module according to the disclosure. 
         [0088]    In addition, as shown on  FIG. 8 , in a case in which the suction fan, installed at the rear side of the swirler fan  100  with the opening at the center thereof, is configured as an axial propeller fan  250 , the outlet of the suction fan case may be assembled to be positioned on the same axis as a point at which the suction fan is disposed. As shown on  FIG. 8 , the outlet  600  may be assembled to the suction fan case or the housing  450 . An opening may be formed at a central portion of the axial propeller fan  250  and between wing frames, so that air flow may be formed therethrough. According to the axial propeller fan  250  of  FIG. 8 , structure of the ventilator module may be simplified. A motor  300  and the axial propeller fan  250  may be received in the suction fan case  450 , and a bell-mouth  500  and the swirler fan  100  may be disposed at a front end of the suction fan case  450 . 
         [0089]      FIG. 9  is an exploded perspective view that illustrates another configuration of a ventilator module according to the disclosure. 
         [0090]    In cases that the ventilator module according to the disclosure is applied in portable ventilation equipments such as a portable dust collector, a portable welding fume extractor, etc., it is necessary to install filters at the of the outlet to eliminate or trap pollutants. In such cases the suction forces of the suction fan  200  in the ventilator module could be decreased due to the pressure drop by filters. To overcome this problem it is necessary to drive the suction fan  200  at the rear portion with stronger rotational power. 
         [0091]    For this application  FIG. 9  illustrates another configuration of a ventilator module according to the disclosure comprising a motor  300  with a motor housing  310  to drive a swirler fan  100 , and another motor  900  with a suction fan case  400  disposed separately with distance to drive a suction fan  200  independently. 
         [0092]      FIG. 10  is a diagram that illustrates the result of simulation of air current and pressure contours formed by the ventilator module according to the disclosure. 
         [0093]    The air current flows along an inclined surface of the bell-mouth  500  and the horizontal end  510 , and flows back forming the donut-like low pressure zone. A significantly strong level of low pressure zone is formed at the center portion of the tornado air current so that the air current ascends at high speed by receiving rising propulsion supplied by the suction fan  200 . In addition,  FIG. 10  shows that the bell-mouth  500  enlarges the capture regions. 
         [0094]      FIG. 11  is a diagram that illustrates the capture region by the result of simulation of air current and velocity contours formed by the ventilator module according to the disclosure. 
         [0095]    It shows that the ventilator module according to the disclosure creates the wider capture region and the deeper capture depth than the conventional fans&#39; as shown on  FIG. 1 . 
         [0096]    With such a mechanism, the ventilator module according to the disclosure can exhibit powerful and speedy discharge effect of pollutants and odors. 
         [0097]    The right of the disclosure is not limited by the embodiment(s) described hereinbefore, but shall be defined according to the description in the scope of claims hereinafter. It is apparent that a person with an ordinary knowledge of the related art to which the disclosure pertains may conduct various alteration or modification within the scope of the right described in the scope of claims.