Patent Publication Number: US-2011052434-A1

Title: Switch and Motor-Cooling Device for an Electric Fan

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a switch and a motor-cooling device for an electric fan, and more particularly to a switch for controlling ON/OFF of the power supply and adjusting the speed of an electric fan 
     2. Description of the Prior Art 
     The existing switches and cooling devices for an electric fan are divided into the following two types: 
     1. One type is as shown in  FIG. 5 , a switch for an electric fan is disposed on a fan body (not shown) outside a housing  62 , and a motor  61  is disposed inside the housing  62 . In order to dissipate the heat generated by the motor  61  and prevent the electric fan from blowing out hot air after a long time use of the motor  61 , the housing  62  is defined with plural air inlet holes  622  in a flat end surface  621  thereof. However, since the end surface  621  is too small, it is incapable of taking in as much cooling air as needed, resulting in low heat dissipation efficiency. In addition, since the switch is disposed on the fan body outside the housing  62 , operating the switch is inconvenient and needs the user to bend his back. 
     2. The other type is as shown in  FIG. 6 , a motor  71  for an electric fan is disposed in a housing  72 , and a switch  73  is disposed at a distal end of a housing  72 . The switch  73  is formed with a protruded arc-shaped end at the distal end of the housing  72 . The housing  72  is defined with plural air inlet holes  721  around the outer periphery thereof. By such arrangements, the area of the housing  72  for sucking cool air is increased, the cool air behind the switch  73 , however, cannot be sucked into the housing  72 . Therefore, improvements are needed. In addition, the arrangement of the air inlet holes  721  greatly increases the total length of the assembly of the switch  73  and the housing  72 , thus occupying much space. 
     The present invention has arisen to mitigate and/or obviate the afore-described disadvantages. 
     SUMMARY OF THE INVENTION 
     The technical problems to be solved: 
     The existing switches and motor-cooling devices for an electric fan have low heat dissipation efficiency due to the poor design of the air inlet holes which cannot take in a large amount of cool air. 
     In order to solve the above technical problem, a switch and a motor-cooling device for an electric fan in accordance with the present invention comprise a motor, a housing, a controller and a knob. The motor is connected to plural fan blades. The housing has one end connected to the motor and an end cap and encloses the motor. The other end of the housing is defined with a concave portion. On the bottom of the concave portion are provided plural assembling portions. The concave portion is formed with an outward-enlarged arc-shaped guiding surface around the periphery thereof and interiorly defined with plural inlet holes. The controller is assembled to the assembling portions in the concave portion and further provided with an assembling rod. The knob and the controller constitute the switch of the present invention. The knob is interiorly defined with an assembling hole to be assembled to the assembling rod and exteriorly formed with a tapered arc-shaped guiding surface. 
     The present invention has the following advantages: 
     The housing is defined with the concave portion in the one end thereof, and the concave portion is formed with the outward-enlarged arc-shaped guiding surface on the periphery thereof and interiorly defined with the plural inlet holes, so the cool air within the angular scope of the outward-enlarged circular guiding surface can be completely sucked into the housing. In addition, although the concave portion is centrally provided with the knob, the knob is formed with the guiding surface to guide the air behind the knob to be sucked into the concave portion. Therefore, the amount of the air for cooling the motor is greatly increased, and the present invention can obtain the optimal heat dissipation efficiency. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a switch and a motor-cooling device for an electric fan in accordance with the present invention; 
         FIG. 2  is an exploded view of the switch and the motor-cooling device for an electric fan in accordance with the present invention; 
         FIG. 3  is a cross-sectional view of the switch and the motor-cooling device for an electric fan in accordance with the present invention; 
         FIG. 4  is a cross-sectional view illustrating how the air is sucked into the concave portion of the housing of the present invention; 
         FIG. 5  is a cross-sectional view of a conventional switch and a conventional motor-cooling device for an electric fan; and 
         FIG. 6  is a cross-sectional view of another conventional switch and another conventional motor-cooling device for an electric fan. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be clearer from the following description when viewed together with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment in accordance with the present invention. 
     Referring to  FIGS. 1-3 , a switch and a motor-cooling device for an electric fan in accordance with the present invention comprise a motor  10 , a housing  20 , a controller  30 , and a knob  40 . 
     The motor  10  is connected to plural fan blades  11 . 
     The housing  20  has one end connected to the motor  10  and an end cap  100  and encloses the motor  10 . The other end of the housing  20  is defined with a concave portion  21 . On a bottom of the concave portion  21  are provided plural assembling portions  22 . The concave portion  21  is formed with an outward-enlarged arc-shaped guiding surface  23  around a periphery thereof. The concave portion  21  is further interiorly defined with plural inlet holes  24 . The housing  20  is further defined with plural air outlet holes  25  in the other end thereof below the concave portion  21 , as shown in  FIG. 2 . 
     The controller  30  controls the speed and ON/OFF of the motor  10  and is assembled to the assembling portions  22  in the concave portion  21 . The controller  30  is provided at both sides thereof with assembling portions  31  to be assembled to the assembling portions  22  by screw. The controller  30  is further provided with an assembling rod  32 . 
     The knob  40  and the controller  30  constitute the switch of the electric fan of the present invention. The knob  40  is interiorly defined with an assembling hole  41  in a surface thereof which is located opposite the controller  30  in such a manner that the assembling hole  41  is assembled to the assembling rod  32 . The knob  40  is exteriorly formed with a tapered arc-shaped guiding surface  42 . The guiding surface  42  is provided with plural anti-slip portions  43  around a periphery thereof. 
     As shown in  FIG. 4 , with the above structure, when the electric fan is turned on to make the motor  10  drive the fan blades  11 , the air will be sucked into the concave portion  21  of the housing  20  and then enter the housing  20  to absorb the heat of the motor  10  to cool the motor  10 . The air which has absorbed the heat of the motor  10  will be discharged though the air outlet holes  25 . By such arrangements, the present invention has the following advantages: when being sucked into the concave portion  21  of the housing  20 , the air will move along the outward-enlarged arc-shaped guiding surface  23  of the concave portion  21 . The air within the angular scope of the outward-enlarged arc-shaped guiding surface  23  will be completely sucked into the concave portion  21 , and even the air behind the knob  40  can also be sucked into the concave portion  21  by cooperating with the guiding surface  42 . Therefore, the amount of the air for cooling the motor  10  is greatly increased. In addition, the air which has absorbed the heat of the motor  10  can be smoothly discharged from the air outlet holes  25 . Therefore, the motor  10  can obtain the optimal heat dissipation efficiency. 
     While we have shown and described various embodiments in accordance with the present invention, it is clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.