Abstract:
A fan unit holds a cooling fan and is detachable from a main body of an inverter apparatus. The fan unit is provided with a fan-unit retainer plate having keyhole-shaped apertures and provided between an upper case and a lower case. The fan unit is fixed by pressing the fan-unit retainer plate with fixing screws. The fan unit is easily and reliably removed by moving the fan-unit retainer plate without directly moving the fan unit and without removing the fixing screws.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is related to Japanese Patent Applications No. 2009-122428, filed May 20, 2009, and 2009-267688, filed Nov. 25, 2009. The contents of these applications are incorporated herein by reference in their entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a fan unit. 
     2. Description of the Related Art 
     For example, in an inverter apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2008-135422 that was published Jun. 12, 2008, heating elements, such as an insulate gate bipolar transistor (IGBT) that generates a high heat, a capacitor, and a reactor, are incorporated in a housing. A heat sink is used to cool these elements, and a cooling fan for forced air cooling is mounted at one end of the housing. 
     When the capacity of the inverter apparatus is small and only one cooling fan will do, a fan case is attached to the housing by engagement of projections without using any fixing screw. In contrast, when the capacity of the inverter apparatus is large and a plurality of cooling fans are used, the fan case is firmly attached to the housing with fixing screws. 
     SUMMARY OF THE INVENTION 
     A fan unit according to an aspect of the present invention includes an upper fan case and a lower fan case stacked and fixed to each other, each of the upper and lower fan cases including at least one cooling fan, the lower fan case including a flange portion to be placed on a fan-unit support member having threaded holes, the flange portion having a plurality of screw passage holes having a diameter larger than a diameter of a head of a fixing screw; and a fan-unit retainer plate slidably placed on an upper surface of the flange portion of the lower fan case, the fan-unit retainer plate having screw passage holes each including a first hole having a diameter smaller than the diameter of the head of the fixing screw and a second hole having a diameter larger than the diameter of the head of the fixing screw. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be described in further detail with reference to the accompanying drawings wherein: 
         FIG. 1  is a perspective view of an inverter apparatus according to an embodiment of the present invention; 
         FIG. 2  is a perspective view of the inverter apparatus shown in  FIG. 1 , from which a fan unit is detached; 
         FIG. 3  is a perspective view of the fan unit shown in  FIG. 2 ; 
         FIG. 4  is an exploded perspective view of the fan unit shown in  FIG. 3 ; 
         FIG. 5  is an enlarged perspective view illustrating the principal part of a fan-unit retainer plate shown in  FIG. 4 ; 
         FIG. 6A  is a plan view illustrating the principal part of the inverter apparatus shown in  FIG. 1  to which the fan unit is attached; 
         FIG. 6B  is a perspective view of a fixing screw in a state shown in  FIG. 6A ; 
         FIG. 6C  is a plan view illustrating a state in which the fan unit is slid for detachment; 
         FIG. 6D  is a perspective view illustrating the fixing screw in the state shown in  FIG. 6C ; 
         FIG. 7  is a perspective view illustrating a state in which the fan unit is being detached from the inverter apparatus shown in  FIG. 1 ; and 
         FIG. 8  is a plan view illustrating formation of an air channel in the fan unit of the inverter apparatus shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     An embodiment of the present invention will be described below with reference to the drawings. While the present invention is applied to an inverter apparatus in this embodiment, the invention is similarly applicable to other electronic apparatuses such as a converter apparatus and a servo amplifier apparatus. 
     Referring to  FIGS. 1 to 8 , an inverter apparatus  1  includes a housing  2  defined by two upper and lower parts. Heating elements  4 , such as an IGBT, mounted on a printed board  3 , capacitors  5  projecting downward, etc. are provided in the upper part of the housing  2 , and air channels  6   a ,  6   b , and  6   c  are provided in the lower part of the housing  2 . In the air channel  6   a , a heat sink  7  is provided in tight contact with the heating elements  4 . The capacitors  5  project downward from the upper part of the housing  2  into the air channels  6   b  and  6   c.    
     A fan unit  8  blows cooling air into the inverter apparatus  1 . The fan unit  8  is attached to one end of the housing  2  serving as a fan-unit support member, and includes a fan case  9  and cooling fans  11   a ,  11   b ,  11   c ,  11   d , and  11   e . The fan case  9  is divided into an upper fan case  9   a  and a lower fan case  9   b  corresponding to the upper and lower parts of the housing  2 . The upper fan case  9   a  and the lower fan case  9   b  are stacked and fixed to each other with fixing screws  10 . For example, two cooling fans  11   a  and  11   b  are arranged side by side in the right-left direction in the upper fan case  9   a , and three fan cases  11   c ,  11   d , and  11   e  are arranged side by side in the right-left direction in the lower fan case  9   b . Guides  12   a  and  12   b  shaped like flat plates are respectively provided on left and right sides of the upper fan case  9   a , and serve to guide attachment and detachment of the fan unit  8 . 
     The lower fan case  9   b  has a flange portion  13  to be placed on a portion of the housing  2  having threaded holes. This flange portion  13  is provided on the periphery of the lower fan case  9   b , and has a plurality of screw passage holes  15  having a diameter larger than the diameter of the heads of the fixing screws  14 . A fan-unit retainer plate  17  is slidably provided on an upper surface of the flange portion  13  of the lower fan case  9   b . The fan-unit retainer plate  17  has screw passage holes, for example, keyhole-shaped apertures  16  each defined by a first hole  16   a  having a diameter smaller than the diameter of the heads of the fixing screws  14  and a second hole  16   b  having a diameter larger than the diameter of the heads of the fixing screws  14 . The fan-unit retainer plate  17  has an annular rectangular shape corresponding to the flange portion  13  provided on the periphery of the lower fan case  9   b.    
     The housing  2  of the inverter apparatus  1  forms the fan-unit support member. At one end of the housing  2  serving as the fan-unit support member, a rectangular opening  18  having a shape corresponding to the shape of the fan unit  8  is provided. 
     On left and right sides of the rectangular opening  18  of the housing  2 , support members  19   a  and  19   b  are provided to fix the guides  12   a  and  12   b  provided at the left and right sides of the upper fan case  9   a  of the fan unit  8 . 
     By being fixed to the housing  2  with the fixing screws  14 , the fan-unit retainer plate  17  of the fan unit  8  housed in the inverter apparatus  1  holds the lower fan case  9   b  down, so that the fan unit  8  is held in the inverter apparatus  1 . 
     In the above-described configuration, the fan unit  8  is detached from the inverter apparatus  1  in the following manner. 
     First, the fixing screws  14  are loosened sufficiently. In this case, it is unnecessary to completely remove the fixing screws  14 . Next, as shown in  FIG. 6C , the fan-unit retainer plate  17  is slid to the right while being in contact with the lower fan case  9   b , and is placed at a position where the large-diameter second holes  16   b  of the keyhole-shaped apertures  16  provided in the fan-unit retainer plate  17  are aligned with the fixing screws  14 , as shown in  FIG. 6D . 
     After confirming that the fan-unit retainer plate  17 , the lower fan case  9   b , and the fixing screws  14  do not interfere with one another, the user pulls the fan unit  8  forward while holding a protruding edge  9   aa  provided in the upper fan case  9   a  of the fan unit  8 , so that the fan unit  8  can be detached from the inverter apparatus  1 . The fan unit  8  is attached by the reverse procedure. 
     The fan unit  8  housed in the inverter apparatus  1  has the above-described configuration, and therefore has the following operational advantages: 
     (1) Since the fan case  9  does not directly have any keyhole-shaped aperture, the heavy fan unit  8  does not need to be slid during attachment and detachment. This allows the fan unit  8  to be attached and detached with a small force. 
     (2) Since the fan unit  8  is not slid, there is no need to ensure a space where the fan unit  8  slides. This achieves size reduction of the inverter apparatus  1 . 
     (3) Since the fan unit  8  can be attached and detached without removing the fixing screws  14 , the fixing screws  14  will not fall into the inverter apparatus  1  or will not be lost. This allows the fan unit  8  to be reliably attached and detached in a short time. 
     The holes provided in the fan-unit retainer plate  17  are not limited to the keyhole-shaped apertures  16 , and for example, may be slots or semicircular holes. In this case, it is also possible to slide the fan-unit retainer plate  17  and to attach and detach the fan unit  8  simply by loosening the fixing screws  14  without completely removing the fixing screws  14 . 
     As shown in  FIG. 7 , a part of the upper fan case  9   a  forms the guides  12   a  and  12   b  shaped like flat plates. The guides  12   a  and  12   b  are in contact with the support members  19   a  and  19   b  of the housing  2  so as to guide attachment and detachment of the fan unit  8 . Hence, the fan unit  8  can be attached and detached easily and reliably. 
     As shown in  FIG. 8 , an air channel  20  is formed by fixing the guides  12   a  and  12   b  to the support members  19   a  and  19   b . This can efficiently cool an adjacent reactor  21  serving as a heating element. 
     The inverter apparatus  1  is attached to a control panel or the like (not shown) in a manner such that the fan unit  8  is provided on the upper side and the heat sink  7  is provided on the rear side. 
     While the flange portion  13  is provided in the lower fan case  9   b  in the above-described embodiment, it may be provided in the upper fan case  9   a.