Patent Publication Number: US-8967975-B2

Title: Centrifugal air blower and air conditioner

Description:
TECHNICAL FIELD 
     The present invention relates to a centrifugal air blower used for an air conditioner or the like, and an air conditioner having the air blower. 
     BACKGROUND ART 
     In general, a centrifugal air blower has been broadly used as an air blower, for an air conditioner or the like, and recently requirements for high performance and reduction of noises have been particularly remarkably stronger, so that a method of enhancing the performance by improving the shape of an impeller (for example, see Patent Document 1). 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: JP-A-Hei-6-101696 
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     However, it has been recently required to enhance the airflow amount of an air blower and reduce the driving force (motor load) from the viewpoint of energy saving. 
     Therefore, an object of the present invention is to solve the problem of the above conventional technique, and provide a centrifugal air blower that can reduce driving force of an air blower. 
     Means of solving the Problem 
     In order to attain the above object, a centrifugal air blower having an impeller comprising a main plate and a plurality of vanes, and a side plate having a suction port and a blow-out port, is characterized in that when the height of the suction port is represented by H, the height of the blow-out port is represented by h, the diameter of the impeller is represented by D and the diameter of the suction port is represented by d, 0.5&lt;h/H&lt;0.8 and 0.78&lt;d/D&lt;0.84 are satisfied. 
     In this case, the diameter D of the impeller and the diameter d of the suction port may satisfy 0.80&lt;d/D&lt;0.83. 
     According to the simulation, it has been found that both the enhancement of the airflow amount (Q)m 3 /s and the reduction of the motor load Watt can be simultaneously satisfied when 0.5&lt;h/H&lt;0.8 and 0.78&lt;d/D&lt;0.84 are satisfied. Further preferably, it has been found that the motor load Watt can be further reduced when the air blower is designed under the condition of h/H=0.65 and 0.80&lt;d/D&lt;0.83. 
     The angle of the suction portion may be substantially equal to 90. 
     The radius of curvature R 1  of the first curved line portion of the side plate may satisfy 20 mm&lt;R 1 &lt;27 mm, and the radius of curvature R 2  of the second curved line portion of the side plate may satisfy 85 mm&lt;R 2 &lt;110 mm, and preferably 90 mm&lt;R 2 &lt;105 mm. 
     According to the simulation, it has been found that both the enhancement of the airflow amount (Q)m 3 /s and the reduction of the motor load Watt can be simultaneously satisfied when the angle of the suction portion is made to approach to 90, the radius of curvature R 1  of the first curved line portion is set to 20 mm&lt;R 1 &lt;27 mm, and the radius of curvature R 2  of the second curved line portion is set to 85 mm&lt;R 2 &lt;110 mm, preferably 90 mm&lt;R 2 &lt;105 mm. 
     Effect of the Invention 
     According to this invention, both the enhancement of the airflow amount (Q)/ 3 /s and the reduction of the motor load Watt can be simultaneously satisfied by designing the air blower under the condition of 0.5&lt;h/H&lt;0.8 and 0.78&lt;d/D&lt;0.84. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       [ FIG. 1 ] is a perspective view showing an apparatus main body of an indoor unit. 
       [ FIG. 2 ] is a plan view when the apparatus main body is viewed from the lower side. 
       [ FIG. 3 ] is a top view of a centrifugal air blower according to an embodiment of the present invention. 
       [ FIG. 4 ] is a cross-sectional view of II-II of  FIG. 1 . 
       [ FIG. 5 ] is a diagram showing the relationship of a suction fan diameter ratio, an airflow amount and a motor load. 
       [ FIG. 6 ] is a diagram showing the relationship of the suction fan diameter ratio, the air flow amount and the motor load. 
       [ FIG. 7 ] is an enlarged cross-sectional view of a side plate. 
       [ FIG. 8 ] is a diagram showing the relationship of an angle of the side plate, the airflow amount and the motor load. 
       [ FIG. 9 ] is a diagram showing the relationship of a radius of curvature R 1 , the airflow amount and the motor load. 
       [ FIG. 10 ] is a diagram showing the relationship of a radius of curvature R 2 , the airflow amount and the motor load. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     An embodiment according to the present invention will be described with reference to the drawings. 
       FIG. 1  is a diagram showing an installation state of an indoor unit of an in-ceiling embedded type air conditioner according to an embodiment. In the following description, the directions of up, down, right, left, etc. mean those directions corresponding to the installation state. 
     This indoor unit  10  is constructed as a so-called ceiling cassette type in which an apparatus main body  20  (housing  21 ) is installed under the roof and a face panel  100  is exposed from the ceiling, and more accurately it is constructed as a four-way ceiling cassette type having four air blow-out ports  120 . 
     The apparatus main body  20  has a metal housing  21  constituting an outer case thereof, and air-conditioning parts such as a centrifugal air blower  33  (see  FIG. 2 ), a heat exchanger (indoor heat exchanger), etc. are mounted in the housing  21 . The housing  21  is formed by sheet metal processing of a metal plate, and it has a top plate portion (top plate)  21   b  and a side plate portion (side plate)  21   c  extending downwardly along the outer edge of the top plate portion  21   b  and is designed in a box-like shape so that the overall lower surface thereof is opened. 
     Hanging clasps  28  for hanging the apparatus main body  20  are provided at four corner portions on the outer surface of the side plate portion  21   c  of the housing  21 . The hanging clasps  28  are secured to hanging bolts  29  under the roof so that the apparatus main body  20  is supported and hung. The apparatus main body  20  may be fixed to holding bars which are provided to the ceiling surface in a grid shape. 
     A face panel  100  is secured to the lower portion of the apparatus main body  20 , that is, the lower portion of the housing  21 . This face panel  100  is formed of a resin panel, and it is designed in a rectangular shape larger than the opening of the lower side of the housing  21 . The face panel  100  has one air suction port  110  for taking indoor air at the center portion thereof, and plural (four in this embodiment) air blow-out ports  120  which extend along the four sides of the face panel  100  around the suction port  110  and through which heat-exchanged air is blown out. 
     A suction grille  111  is freely detachably mounted at the air suction port  110  of the face panel  100 , an air filter (not shown) is mounted at the suction grille  111 , and indoor air sucked into the air suction port  110  is cleaned by the air filter. Louvers  122  for changing the air flowing direction are arranged at the air blow-out ports  120  of the face panel  100 , and the louvers  122  are turned by the driving of motors (not shown). 
     Corner panels  102  are secured to the four corner portions of the face panel  100 . The corner panels  102  are configured to be detachable to the lower side of the face panel  100 , and have such a size so as to grant a worker access to the engaging position of the hanging clasp  28  and the hanging bolt  29  when a corner panels  102  is detached. 
       FIG. 2  is a perspective view showing the apparatus main body  20  of the indoor unit  10 , and it is illustrated together with an outdoor air introducing part which is prepared as an option by a maker in consideration of such a situation that the indoor unit  10  is installed at a place to which a building management law for high-rise floors of buildings, etc. is applied. Reference numeral  50  represents a ventilation duct for introducing outside air, reference numeral  55  represents a duct joint part for joining the ventilation duct  50  to the housing  21  of the indoor unit  10 , and reference numeral  60  represents an outdoor air introducing box (outdoor air introducing part) secured in the housing  21  of the indoor unit  10 . 
     A heat insulating member  30  formed of foam polystyrene is disposed inside the housing  21 . This heat insulating member  30  is equipped with a top plate heat insulating portion disposed substantially over the whole surface of the top plate portion (top plate)  21   b  of the housing  21 , and a side plate heat insulating portion  30   c  disposed substantially over the whole surface of the side plate portion  21   c  of the housing  21  which are provided integrally with each other, and designed in a box-like shape which is opened at the lower side thereof. That is, this heat insulating member  30  is covered on the overall inner surface of the housing  21  to insulate heat between the inside and outside of the housing  21 , thereby establishing a heat insulating structure, and air conditioning parts such as the centrifugal air blower  33 , the heat exchanger, etc. are mounted in the thus heat-insulated inner space. 
     As shown in  FIG. 2 , the centrifugal air blower  33  comprises a fan motor  33   a  which is provided substantially at the center of the housing  21  (the position corresponding to the center portion of the top plate portion  21   b ) and secured to the top plate portion  21   b  of the housing  21  with the motor shaft thereof being oriented to the lower side, and an impeller  1  secured to the motor shaft of the fan motor  33   a . Air in a room to be air-conditioned (indoor air) is sucked from the air suction port  110  of the face panel  100  by rotation of the impeller  1 , and blown out in the centrifugal direction. 
       FIG. 3  is a top view of the centrifugal air blower  33 , and FIG. is a cross-sectional view of II-II of  FIG. 3 . 
     In  FIG. 3  and  FIG. 4 ,  1  represents the impeller, and the impeller  1  has plural vanes  2 , a main plate  3  to which the vanes  2  are fixed, and a side plate  4  which is fixed to the end faces of the vanes  2  at the opposite side to the main plate and has a suction port  4   a . In  FIG. 4 ,  5  represents a motor which is directly connected to the impeller  1 , and the motor  5  is fixed to a casing (not shown) in which the motor  5  and the impeller  1  are mounted. When the motor  5  is driven, the impeller  1  of the centrifugal air blower  33  is rotated, and air sucked from the air suction port  4   a  is blown out sideward by a centrifugal force. 
     The inventors have introduced shape factors of the air blower for satisfying both enhancement of the airflow amount of the centrifugal air blower  33  and reduction of the load of the motor  5  simultaneously through a simulation. In  FIG. 4 , first, when the height H of the air suction port, the height h of the air blow-out port, the diameter D of the impeller  1  and the diameter d of the air suction port  4   a  are set as parameters, the inventors have found how the variation of these shape factors act on the enhancement of the airflow amount of the centrifugal air blower  33  and the reduction of the load of the motor  5 . 
       FIG. 5  shows the suction/fan diameter ratio (d/D) on the abscissa axis, the airflow amount (Q)m 3 /s on the ordinate axis at the left side and the motor load Watt on the ordinate axis at the right side. In  FIG. 5 , diamonds represent an air blower of h/H=0.50, circles represent an air blower of h/H=0.65, and triangles represent an air blower of h/H=0.80. According to this simulation, it has been found that the air blower which is designed in the neighborhood of h/H=0.65 (sign of circle) and d/D=0.82 brings the largest airflow amount (Q)m 3 /s and the smallest motor load Watt, thereby achieving the highest performance. 
     Here, when specifically reviewing the airflow amount (Q)m 3 /s of the centrifugal air blower  33 , for all the air blowers satisfying 0.50&lt;h/H&lt;0.80, the airflow amount trends to increase as a whole until d/D reaches 0.78. 
     For the air blower of h/H=0.65 (sign of circle), the airflow amount increases from d/D=0.78 till d/D=0.82, and it turns into decrease when d/D exceeds 0.82. Furthermore, for the air blower of h/H=0.50 (sign of diamond) when d/D exceeds 0.78, the airflow amount is substantially fixed until d/D increases to 0.82. When d/D exceeds 0.82 again, the airflow amount turns into increase again. For the air blower of h/H=0.80 (triangle sign), even when d/D exceeds 0.78, the increasing trend of the airflow amount continues until h/H reaches 0.85. 
     Therefore, d/D is limited to the range of 0.78&lt;d/D&lt;0.85, and data (solid line) of h/H=0.55 (sign of x), h/H=0.60 (rectangle sign) and h/H=0.70 (sign of x+vertical line) are further added in addition to h/H=0. 5 (sign of diamond), h/H=0.65 (sign of circle) and h/H=0.8 (triangle sign) described above, and the resultant data are shown in  FIG. 6 . 
     When the trend of the three added data is further analyzed, for the air blowers of h/H=0.55 (sign of x) and h/H=0.70 (sign of x+vertical line), the trend of increase continues until d/D=0.85 even when d/D exceeds 0.78. Furthermore, for the air blower of h/H=0.60 (rectangle sign), the airflow amount increases from d/D=0.78 to d/D=0.82, and it neither increases nor decreases when d/D exceeds 0.82. 
     As a result, in the range of 0.78&lt;d/D&lt;0.85 shown in the abscissa axis direction of  FIG. 6 , the air blower designed under h/H=0.65 (sign of circle) keeps a high airflow amount, and the airflow amount becomes small even when h/H is smaller or larger than 0.65. 
     Furthermore, when the motor load Watt of the centrifugal air blower  3  is reviewed, in the range of 0.65&lt;d/D&lt;0.85 shown in the abscissa axis direction of  FIG. 5 , for h/H=0.5 (sign of diamond), h/H=0.65 (sign of circle) and h/H=0.8 (sign of triangle), the motor load Watt gradually decreases as a whole, and for h/H=0.65 (sign of circle), a local minimum value appears in the neighborhood of d/D=0.82. 
     Therefore, the range of d/D is limited to 0.78&lt;d/D&lt;0.85, and data (broken line) of h/H=0.55 (sign of x), h/H=0.60 (rectangle sign) and h/H=0.70 (sign of x+vertical line) are further added in addition to h/H=0.5 (sign of diamond), h/H=0.65 (sign of circle) and h/H=0.8 (triangle sign) described above, and the resultant data are shown in  FIG. 6 . 
     When the trend is further analyzed while containing the added three data, the air blower of h/H=0.55 (sign of x) has the lowest motor load Watt from d/D=0.78 till d/D=0.80, and has higher values for other values of d/D. However, the air blower of h/H=0.65 (sign of circle) has the lowest motor load Watt from d/D=0.80 till d/D=0.83. 
     Regarding the motor load Watt, it has been found that 0.78&lt;d/D&lt;0.85 or 0.79&lt;d/D&lt;0.84 is preferable, and 0.80&lt;d/D&lt;0.83 is further preferable. 
     From this simulation, in order to reduce the motor load Watt while keeping the airflow amount (Q)m 3 /s of the centrifugal air blower  33  to a high value, it has been found that the design based on h/H=0.6 (sign of circle) and 0.80&lt;d/D&lt;0.83 is desired. 
     As described above, it has been found that the enhancement of the airflow amount (Q)m 3 /s and the reduction of the motor load Watt can be simultaneously satisfied when the centrifugal air blower  33  of this embodiment is designed under the condition of 0.5&lt;h/H&lt;0.8 and 0.78&lt;d/D&lt;0.85. More preferably, it has been also found that the motor load Watt can be further reduced when the air blower is designed under the condition of h/H=0.65 and 0.80&lt;d/D&lt;0.83. 
       FIG. 7  is an enlarged view of a side plate (shroud)  4  of the centrifugal air blower  33  shown in  FIG. 4 . 
     The side plate  4  of this centrifugal air blower  33  comprises a suction portion  4   b  extending substantially linearly, a first curved line portion  4   c  intercommunicating with the suction portion  4   b  and a second curved line portion  4   d  intercommunicating with the first curved line portion  4   c . The radius of curvature R 1  of the first curved line portion  4   c  and the radius of curvature R 2  of the second curved line portion  4   d  have the relationship of R 1 &lt;R 2 , and also in this air blower, the impeller  2  extends beyond the first curved line portion  4   c  inside the side plate  4  and reaches the suction portion  4   b  as shown in  FIG. 4 . 
     The radius of curvature R 1  and the radius of curvature R 2  are set as parameters, and it has been found how the variation of these shape values contribute to the enhancement of the airflow amount (Q)m 3 /s of the centrifugal air blower  33  and the reduction of the load Watt of the motor  5 . 
       FIG. 8  shows the relationship of the angle of the suction portion  4   b , the airflow amount (Q) m 3 /s and the motor load Watt,  FIG. 9  shows the relationship of the radius of curvature R 1  of the first curved line portion  4   c , the airflow amount (Q)m 3 /s and the motor load Watt, and  FIG. 10  shows the relationship of the radius of curvature R 2  of the second curved line portion  4   d , the airflow amount (Q)m 3 /s and the motor load Watt. 
     First, as shown in  FIG. 8 , when the angle of the suction portion  4   b  increases, the motor load Watt decreases. When the angle approaches 90, the motor load Watt is equal to a minimum value. On the other hand, when the angle of the suction portion  4   b  increases, the airflow amount (Q)m 3 /s increases, and when the angle reaches 90, no variation is observed after that. 
     Accordingly, according to a simulation result, it is desired that the angle of the suction portion  4   b  of the side plate  4  approaches to 90. 
     Regarding the radius of curvature R 1  of the first curved line portion  4   c , it has been found that the enhancement of the airflow amount (Q)m 3 /s and the reduction of the motor load Watt can be performed in the range of 20 mm&lt;R 1 &lt;27 mm as shown in  FIG. 9 . When the radius of curvature R 1  exceeds 27 mm, the airflow amount (Q)m 3 /s shifts to decrease, and the motor load Watt shifts to increase. 
     Accordingly, according to a simulation result, it is desired that the air blower is designed on the condition of 20 mm&lt;R 1 &lt;27 mm for the radius of curvature R 1 . 
     As shown in  FIG. 10 , regarding the radius of curvature R 2  of the second curved line portion  4   d , it has been found that a local maximum value appears at R 2 =90 mm. 
     The airflow amount (Q)m 3 /s trends to increase until R 2 =90 mm. When R 2  exceeds 90 mm, the airflow amount (Q)m 3 /s shifts to moderate decrease. On the other hand, the motor load Watt trends to decrease until R 2 =90 mm, however, when R 2  exceeds 90 mm, the motor load Watt shifts to moderate increase. 
     Accordingly, according to a simulation result, the air blower is designed so as to satisfy 85 mm&lt;R 2 &lt;110 mm for the radius of curvature R 2 , and preferably 90 mm&lt;R 2 &lt;105 mm. 
     As described above, according to the centrifugal air blower of this embodiment, when the angle of the suction portion  4   b  of the side plate  4  is made to approach to 90, the radius of curvature R of the first curved line portion  4   c  is set to satisfy 20 mm&lt;R 1 &lt;27 mm, and the radius of curvature R 2  of the second curved line portion  4   d  is set to satisfy 85 mm&lt;R 2 &lt;110 mm, preferably 90 mm&lt;R 2 &lt;105 mm, whereby the enhancement of the air flow amount (Q)m 3 /s and the reduction of the motor load Watt can be simultaneously satisfied. 
     Description of Reference Numerals 
     
         
         
           
               1  impeller 
               2  vanes 
               3  main plate 
               4  side plate 
               5  motor 
               10  indoor unit (air conditioner) 
               20  apparatus main body 
               21  housing 
               30  heat insulating material 
               33  air blower 
               50  ventilation duct 
               55  duct joint part 
               100  face panel 
               110  suction port 
               111  suction grille 
               120  air blow-out port