Patent Publication Number: US-2015071781-A1

Title: Centrifugal fan and air-conditioning apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to a centrifugal fan or the like that draws a gas by suction in the direction of the axis of rotation and blows out the gas in directions intersecting the axis of rotation. 
     BACKGROUND ART 
     For example, an impeller used in a centrifugal fan has mainly employed two-dimensional blades not having a twisted shape between a main plate and a shroud. For this reason, in general, a main plate and blades can be integrally molded using, for example, a resin. However, in order to achieve further noise reduction, power consumption reduction, and the like, for example, a centrifugal fan is required whose blades disposed between a main plate and a shroud are, for example, three-dimensional blades. 
     When a centrifugal fan (impeller) has three-dimensional blades, in order to improve the degree of freedom of resin molding, the impeller (particularly each blade) is often manufactured by, for example, separately molding a plurality of components, assembling the plurality of molded components, and fixing them by joining or the like. By dividing the impeller into a plurality of components, blades or the like having a complex shape can be obtained. If blades have a hollow structure in this case, a lightweight arrangement can be achieved (see, for example, Patent Literature 1). 
     For example, in the fitting parts of a plurality of components forming a three-dimensional blade of an axial fan, the assembled components are fitted to each other, fitting lines formed between the components are bent in a zigzag manner, spot ultrasonic joining is performed at the bending points, and the number of joints is thereby increased to improve the joining strength (see, for example, Patent Literature 2). 
     CITATION LIST 
     Patent Literature 
     [Patent Literature 1] Japanese Patent No. 4432474 (FIGS. 5 &amp; 6) 
     [Patent Literature 2] Japanese Unexamined Patent Application Publication No. 10-122196 (FIG. 1) 
     SUMMARY OF INVENTION 
     Technical Problem  
     As described above, an impeller part of a centrifugal fan is manufactured by dividing it into a plurality of components (for example, a main plate, a shroud, and blades), and then the components are fixed to each other by joining or the like. For example, the blades disposed between the main plate and the shroud are welded to the main plate and the shroud by irradiation with laser light, application of ultrasonic vibration, or the like. During welding, a pressure is applied between the blades and the main plate, and between the blades and the shroud, and the welding surfaces are pressed against and brought into close contact with each other so as to be joined firmly. 
     For example, particularly when the blades have a hollow structure, the blades may significantly deform depending on an external pressure. For example, if the blades significantly deform during welding, breakage, failure in joining due to decreased closeness of contact of welding surfaces, or the like may occur, leading to a decrease in reliability, generation of noise, and the like. 
     The present invention has been made to solve the above problem, and has as its object to obtain a centrifugal fan or the like resistant to an external pressure. 
     Solution to Problem 
     A centrifugal fan according to the present invention includes a main plate fixed to a rotating shaft of a drive unit, a shroud having an air suction port, and a plurality of blades disposed between the main plate and the shroud. A rib is formed in the hollow structure of each of the blades. 
     Advantageous Effects of Invention 
     With the centrifugal fan according to the present invention, a rib is provided in each of the blades. Therefore, deformation of the blades due to an external pressure can be suppressed, and a decrease in reliability, generation of noise, and the like due to deformation can be suppressed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       [ FIG. 1 ]  FIG. 1  is a perspective view showing the configuration of a centrifugal fan according to Embodiment 1 of the present invention. 
       [ FIG. 2 ]  FIG. 2  is a diagram showing the schematic configuration of a cross-section of an impeller of the centrifugal fan according to Embodiment 1 of the present invention. 
       [ FIG. 3 ]  FIG. 3  is a perspective view showing the configuration of a blade of the centrifugal fan according to Embodiment 1 of the present invention. 
       [ FIG. 4 ]  FIG. 4  is a sectional view showing the configuration of the blade of the centrifugal fan according to Embodiment 1 of the present invention as viewed from the side. 
       [ FIG. 5 ]  FIG. 5  is a diagram showing the schematic configuration of the impeller of the centrifugal fan according to Embodiment 1 of the present invention as viewed from the front of the blade. 
       [ FIG. 6 ]  FIG. 6  is a perspective view showing the configuration of a main blade of the centrifugal fan according to Embodiment 1 of the present invention. 
       [ FIG. 7 ]  FIG. 7  is a perspective view showing the configuration of a main blade of a centrifugal fan according to Embodiment 2 of the present invention. 
       [ FIG. 8 ]  FIG. 8  is a perspective view showing the configuration of a main blade of a centrifugal fan according to Embodiment 3 of the present invention. 
       [ FIG. 9 ]  FIG. 9  shows an air-conditioning apparatus according to Embodiment 5 of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Centrifugal fans and the like according to embodiments of the present invention will now be described with reference to the accompanying drawings and the like. In the accompanying drawings, the same reference numerals denote the same or equivalent components, and are common throughout embodiments to be described below. The forms of components described in the specification in its entirety are merely illustrative, and the present invention is not limited to the forms described in the specification. In particular, combinations of components are not limited to those in each embodiment, and components described in one embodiment can be applied to another embodiment. Also in the drawings, the relationship in size between components is often different from the actual one. 
     Embodiment 1 
       FIG. 1  is a perspective view showing the configuration of a centrifugal fan according to Embodiment 1 of the present invention.  FIG. 2  is a diagram showing the schematic configuration of a cross-section of an impeller of the centrifugal fan according to Embodiment 1 of the present invention, The impeller  100  of the centrifugal fan according to Embodiment 1 is provided with a plurality of blades  2  (seven blades  2  in  FIG. 1 ) between a shroud  1  and a main plate  3 , as shown in  FIGS. 1 and 2 . 
     The shroud  1  has a bell mouth shape and includes an air suction port  1   a.  The blades  2  of Embodiment 1 are three-dimensional blades having a twisted shape between the shroud  1  and the main plate  3 . Therefore, noise reduction, power consumption reduction, and the like can be achieved. A boss  4  serving as a rotating shaft is attached to the center of the main plate  3 . A drive unit (a fan motor or the like) is attached to the boss  4 , and rotates the impeller  100 . Upon rotation, the impeller  100  draws a gas (for example, air) by suction in the direction of the axis of rotation and blows out the drawn gas in outer peripheral directions intersecting the axis of rotation. The shroud  1 , the blades  2 , and the main plate  3  are made of a resin. The details of the shroud  1 , the blades  2 , and the main plate  3  will be described later. 
       FIG. 3  is a perspective view showing the configuration of a blade of the centrifugal fan according to Embodiment 1 of the present invention.  FIG. 4  is a sectional view showing the configuration of the blade of the centrifugal fan according to Embodiment 1 of the present invention as viewed from the side (in a direction almost perpendicular to that in which the blade cuts through air). As shown in  FIGS. 3 and 4 , in Embodiment 1, a blade  2  is fabricated by assembling a plurality of components (a main blade  5  and a blade cover  6 ). In assembling, the main blade  5  and the blade cover  6  may be fixed to each other only by fitting. In this case, for example, a protruding portion (not shown) on the surface, facing a hollow portion  9 , of the blade cover  6  is fitted into and fixed to a boss  5   e  (see  FIG. 6 ; to be described later) on the surface, facing the hollow portion  9 , of the main blade  5 . Depending on circumstances involved, in addition, joining and fixing may be performed by bonding, welding, or the like. In Embodiment 1, in the blade  2 , the main blade  5  forms the whole of a suction surface  5   a  and a part o a pressure surface  6   a.  Also, the blade cover  6  forms the rest of the pressure surface  6   a,  which is not formed by the main blade  5 . Note that the relationship between the pressure surface  6   a  and the suction surface  5   a  formed by the main blade  5  and the blade cover  6  is not limited to this. Although, in Embodiment 1, each blade  2  is fabricated by assembling two components, namely, the main blade  5  and the blade cover  6 , the number of components is not limited. Each blade  2  may be fabricated by assembling three or more components in conformity to its shape. By assembling the main blade  5  and the blade cover  6 , a space serving as the hollow portion  9  is formed between the main blade  5  and the blade cover  6 . By making the blades  2  hollow, a lightweight arrangement of the impeller  100 , low material costs, and the like can be achieved. 
       FIG. 5  is a diagram showing the schematic configuration of a cross-section of the impeller of the centrifugal fan according to Embodiment 1 of the present invention as viewed from the front of a blade (in the direction in which the blade cuts through air). As shown in  FIGS. 3 and 5 , the main blade  5  has a shroud-side side surface  5   b  that comes into contact with the shroud  1  and serves as a welding surface and a main-plate-side side surface  5   c  that comes into contact with the main plate  3  and serves as a welding surface. The blade  2  formed by assembling the main blade  5  and the blade cover  6  is placed between the shroud  1  and the main plate  3 . 
     Since the shroud  1  has a shape with a curved surface, it is difficult to perform positioning or the like for the shroud  1  relative to the blade  2  (main blade  5 ). So, a protruding portion  5   d  whose top surface serves as a welding surface (contact surface) to be welded to the shroud  1  is formed on the shroud-side side surface  5   b  of the main blade  5  (blade  2 ), and a recessed portion  1   b  is formed in the shroud  1  so that the protruding portion  5   d  and the recess  1   b  can be fitted together. Therefore, the shroud  1  and the blades  2  can easily, reliably be positioned and welded. On the other hand, the main plate  3  has a recessed portion  3   a.  By placing the main-plate-side side surface  5   c  on the bottom surface portion of the recessed portion  3   a,  the main plate  3  and the blades  2  can easily, reliably be positioned and welded. By irradiation with laser light, application of ultrasonic vibration, or the like, the contact surface, such as the top surface of the protruding portion  5   d,  of the shroud-side side surface  5   b  of the main blade  5  (blade  2 ) is heated and welded to the shroud  1 , The main-plate-side side surface  5   c  is heated and welded to the main plate  3 . 
     Thus, the shroud  1  and the main plate  3  are joined to the main blade  5  by welding to fix the blade  2 . In welding, the shroud  1  and the blade  2  are pressurized so that the shroud-side side surface  5   b  and the main-plate-side side surface  5   c  come into close contact with the shroud  1  and the main plate  3 . The main plate  3  and the blade  2  are also pressurized. Since the blade  2  has the hollow portion  9  as an internal construction, for example, breakage may occur due to a pressure. For example, owing to deformation or the like of the blade  2 , the shroud  1  and the blade  2 , and the main plate  3  and the blade  2  may not be brought into close contact with each other. So, it is necessary to take measures so that the blade  2  is not broken by such an external pressure. 
       FIG. 6  is a perspective view showing the configuration of the main blade of the centrifugal fan according to Embodiment 1 of the present invention. In Embodiment 1, the main blade  5  is provided with ribs  10  for reinforcement so that the blade  2  has a rigidity sufficient to withstand an external pressure (particularly during welding). The ribs  10  are formed across the entire length between the shroud-side side surface  5   b  and the main-plate-side side surface  5   c.  Since the blade  2  is a three-dimensional blade, the ribs  10  are provided in the hollow portion  9  in Embodiment 1. By providing the ribs  10  in the hollow portion  9 , the shroud-side side surface  5   b  and the main-plate-side side surface  5   c  can be supported from the inside. In addition, the flow of air is not affected. 
     The ribs  10  must not hamper the assembly of the main blade  5  and the blade cover  6 . Therefore, the height of the ribs  10  (their height from the surface, on the back side of the suction surface  5   a,  of the main blade  5 ) preferably conform to at least the shape of a portion (the inner wall surface) facing the hollow portion  9  of the blade cover  6 . 
     As described above, the main blade  5  is made of a resin. For example, if ribs  10  are formed on the surface, on the back side of the welding surface (contact surface), of the shroud-side side surface  5   b  or the like, shrinkage after molding is significant, and sink marks (depressions generated due to shrinkage) may be generated. So, in Embodiment 1, ribs  10  are formed so as to be continuous with the side wall surfaces of the protruding portion  5   d.  Therefore, no sink marks are generated in the welding surface of the shroud-side side surface  5   b  welded to the shroud  1 , and therefore the closeness of contact can be maintained. 
     As described above, in the centrifugal fan according to Embodiment 1, the blades  2  of the impeller  100  are provided with ribs  10 , and therefore the deformation of the blades  2  due to an external pressure can be suppressed, and breakage, and failure in close contact between the shroud  1  and the main plate  3  can be suppressed. Therefore, the reliability can be maintained (a decrease in reliability due to deformation can be suppressed). In addition, the blades  2  can be firmly fixed to the shroud  1  and the main plate  3 , and generation of noise can be suppressed. Since the ribs  10  extend across the length from the shroud-side side surface  5   b  to the main-plate-side side surface  5   c,  the ribs function effectively against the pressure acting during welding. In Embodiment 1, the ribs  10  are formed in the hollow portion  9 , and therefore can be supported at positions close to the welding surface (contact surface). When the centrifugal fan is driven, the ribs do not obstruct the flow of air. For example, by forming ribs  10  (particularly in the height direction) such that they conform to the shape of the blade cover  6 , the main blade  5  and the blade cover  6  can be prevented from deforming toward the hollow portion  9 . Since the blades  2  have a hollow portion  9  (hollow structure) as an internal construction, a lightweight arrangement can be achieved. 
     For example, since a protruding portion  5   d  is formed on the shroud-side side surface  5   b  of the main blade  5  so as to be fitted in the recessed portion  1   b  of the shroud  1 , the positioning of the shroud  1  and the blade  2  is facilitated, and joining by, for example, welding can be performed firmly. Since the ribs  10  are formed so as to be continuous with the side wall surfaces of the protruding portion  5   d  so that no sink marks are generated on the back side of the welding surface (contact surface), the closeness of contact of the welding surface can be improved. 
     Embodiment 2 
       FIG. 7  is a perspective view showing the configuration of a main blade of a centrifugal fan according to Embodiment 2 of the present invention. In  FIG. 7 , the same reference numerals as in  FIG. 6  denote members having the same functions as those described in Embodiment 1. For example, in Embodiment 1, ribs  10  are provided for reinforcement so that blades  2  can withstand an external pressure (particularly during welding). The ribs  10  increase the weight of the blade  2  and, in turn, that of the impeller  100 . Therefore, the ribs  10  are preferably as light in weight as possible, To attain this, in the impeller  100  of the centrifugal fan of Embodiment 2, a lightweight arrangement of the impeller  100  is achieved by varying the height of the ribs  10  (particularly by forming them to be partially low) while securing the function of ribs  10 . 
     As described in Embodiment 1, if ribs  10  are provided on the back side of the welding surface, sink marks may be generated. Since the main-plate-side side surface  5   c  is in its entirety in contact with the main plate  3 , ribs  10  need to be formed directly on the back side of the main-plate-side side surface  5   c.  For this reason, referring to  FIG. 7 , in particular, the ribs  10  on the back side of the main-plate-side side surface  5   c  are formed low. By making the areas of the ribs  10  formed on the back side of the main-plate-side side surface  5   c  as small as possible, a lightweight arrangement is achieved, sink marks generated during welding are kept small in size, and the closeness of contact between the blade  2  (main blade  5 ) and the main plate  3  is maintained. 
     As described above, in the impeller  100  of the centrifugal fan of Embodiment 2, a lightweight arrangement of the impeller  100  can be achieved by varying the height of the ribs  10  formed in the hollow portion  9  of the blade  2 . 
     The amount of material used can be kept small to achieve low costs, In particular, by forming low portions of the ribs  10  on the back side of the main-plate-side side surface  5   c  that comes into contact with the main plate  3 , and making the areas of contact between the main plate  3  and the ribs  10  small so that sink marks generated during welding are kept small in size, the closeness of contact between the blade  2  (main blade  5 ) and the main plate  3  is maintained, and therefore a highly reliable low-noise impeller  100  can be obtained. 
     Embodiment 3 
       FIG. 8  is a perspective view showing the configuration of a main blade of a centrifugal fan according to Embodiment 3 of the present invention. In  FIG. 8 , the same reference numerals as in  FIG. 6  denote members having the same functions as those described in Embodiment 1. In Embodiment 2, a lightweight arrangement is achieved by varying the height of ribs  10 . In particular, the areas of the ribs  10  formed on the back side of the man-plate-side side surface  5   c  are made as small as possible so that sink marks generated during welding are kept small in size. 
     In the impeller  100  of the centrifugal fan of Embodiment 2, a lightweight arrangement of the impeller  100  is achieved by varying the thickness of the ribs  10  (particularly by forming them to be partially thin) while securing the function of ribs  10 . For example, as shown in  FIG. 8 , by making the thickness of ribs  10  on the back side of the main-plate-side side surface  5   c  small, and making the areas of the ribs  10  as small as possible, a lightweight arrangement is achieved, sink marks generated during welding are kept small in size, and the closeness of contact between the blade  2  (main blade  5 ) and the main plate  3  is maintained. 
     As described above, in the impeller  100  of the centrifugal fan of Embodiment 3, a lightweight arrangement of the impeller  100  can be achieved by varying the thickness of the ribs  10  formed in the hollow portion  9  of the blade  2 . The material used can be reduced, and cost reduction can be achieved. In particular, by forming thin portions of the ribs  10  on the back side of the main-plate-side side surface  5   c  that comes into contact with the main plate  3 , and making the areas of contact between the main plate  3  and the ribs  10  small so that sink marks generated during welding are kept small in size, the closeness of contact between the blade  2  (main blade  5 ) and the main plate  3  is maintained, and therefore a highly reliable low-noise impeller  100  can be obtained. 
     Embodiment 4 
     In Embodiment 1, the main blade  5  forms the whole of the suction surface  5   a  and a part of the pressure surface  6   a,  and the blade cover  6  forms the rest of the pressure surface  6   a.  However, the present invention is not limited to this. The blade cover  6  may be located on the suction surface side. 
     In Embodiment 2, the height of the ribs  10  is varied. In Embodiment 3, the thickness of the ribs  10  is varied. However, the present invention is not limited to either of them. Both the height and thickness of the ribs  10  may be varied. 
     The blades  2  in Embodiments 1 to 3 are three-dimensional blades. However, the present invention is not limited to this, and can also be applied to two-dimensional blades (particularly those having a hollow structure). 
     Although, in Embodiments 1 to 3, joining by welding has been described, the present invention is not limited to this, and can also be applied, for example, to a case where the shroud  1  and the main plate  3  are bonded to the blades  2  by pressurization. 
     Although, in Embodiments 1 to 3, ribs  10  are formed in two portions in the hollow portion  9 , the present invention does not limit the number of ribs, where to form ribs, and the like. However, in terms of attaining a lightweight arrangement, the number of ribs  10  formed is preferably small. 
     Embodiment 5 
       FIG. 9  is a diagram showing an air-conditioning apparatus according to Embodiment 5 of the present invention.  FIG. 9  is a partial sectional view showing the configuration of a ceiling-embedded indoor unit of the air-conditioning apparatus. In  FIG. 9 , the same reference numerals denote the same devices as those described in, for example, Embodiment 1. 
     The ceiling-embedded indoor unit  20  according to Embodiment 5 is embedded in a ceiling  30 , and a lower surface opening is open from an opening  31  of the ceiling  30 . From the lower surface opening of a body shell  21  to the periphery of the opening  31  of the ceiling  30 , a decorative panel  22  having an air inlet  23  and an air outlet  24  is attached. A filter  25  is disposed on the downstream side of the air inlet  23 . 
     A fan motor  26  serving as a drive unit is attached to a top plate of the body shell  21 . The boss  4  of the impeller  100  of the centrifugal fan disposed so that the air suction port  1   a  of the shroud  1  faces the air inlet  23  of the decorative panel  22  is fixed to the output shaft of the fan motor  26 . A bell mouth  27  is placed between the air inlet  23  of the decorative panel  22  and the air suction port  1   a  of the shroud  1  of the impeller  100  of the centrifugal fan. A heat exchanger  28  is placed in an air passage leading from the air inlet  23  to the air outlet  24  and on the outer periphery of the impeller  100  of the centrifugal fan on the downstream side. 
     In the air-conditioning apparatus having the above-described ceiling-embedded indoor unit  20 , when its operation starts, the fan motor  26  of the centrifugal fan is rotated, and the impeller  100  fixed to it rotates. Indoor air is drawn by suction upon the rotation of the impeller  100  through the air inlet  23 , is cleaned by the filter  25 , flows into the impeller  100  through the hell mouth  27 , and flows out of the impeller  100  through the gaps between the blades  2  toward its outer periphery. The air flowing out of the impeller  100  passes through the heat exchanger  28 , turns into cold or hot conditioned air, and is blown out through the air outlet  24  into the room. 
     Since the air-conditioning apparatus of Embodiment 5 has a centrifugal an employing the centrifugal fan impeller  100  described in each of Embodiments 1 to 4, a high-strength, low-noise, and energy-saving air-conditioning apparatus can be obtained. 
     The above description assumes that a centrifugal fan according to the present invention is employed in the indoor unit (see  FIG. 9 ) of an air-conditioning apparatus. However, the present invention is not limited to this. A centrifugal fan according to the present invention can be employed in an indoor unit having another structure. A centrifugal fan according to the present invention can also be employed in an outdoor unit of an air-conditioning apparatus, an air cleaner, and the like. 
     REFERENCE SIGNS LIST 
       1 : shroud,  1   a:  air suction port.  1   b:  recessed portion,  2 : blade.  3 : main plate,  3   a:  recessed portion,  4 : boss,  5 : main blade,  5   a:  suction surface,  5   b:  shroud-side side surface,  5   c:  main-plate-side side surface,  5   d:  protruding portion,  5   e:  boss,  6 : blade cover,  6   a:  pressure surface,  9 : hollow portion,  10 : rib,  20 : indoor unit,  21 : body shell,  22 : decorative panel,  23 : air inlet,  24 : air outlet,  25 : filter,  26 : fan motor,  27 : bell mouth,  28 : heat exchanger,  30 : ceiling,  31 : opening,  100 : impeller