Patent Publication Number: US-6218653-B1

Title: Cooling structure for ventilation-hooded microwave ovens

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates, in general, to a cooling structure for ventilation-hooded microwave ovens, and more particularly, to an improved cooling structure for effectively cooling electronic equipment generating microwaves by introducing an air current into the cooking cavity of such an oven using a cooling fan mounted to the upper portion of the microwave oven. 
     2. Description of the Background Art 
     As well known to those skilled in the art, in a conventional OTR (over the range), a microwave oven is installed over a gas oven and generates microwaves to heat food in its cooking cavity. A collateral function of the microwave oven is to exhaust the smoke of the gas oven into the atmosphere. 
     FIG. 1 is a schematic view showing the construction of a conventional ventilation-hooded microwave oven. 
     As shown in FIG. 1, such a microwave oven comprises a cavity assembly  10 , including a cavity  12  for cooking, and an instrument compartment  14  mounted to the outside wall of the cooking cavity  12 . Electronic equipment is embedded in the instrument compartment  14  while an air duct  20  is mounted to the top portion of the cooking cavity assembly  10 . 
     A magnetron mount plate  13  is protrusively mounted in the instrument compartment  14 . Also, both the electronic equipment for generating microwaves and an exhaust passage serving to ventilate smoke are mounted in the instrument compartment  14 . 
     A magnetron  16  for oscillating microwaves is fixed to the mount plate  13 , while a high voltage transformer  11  for supplying a high voltage to the magnetron  16  is mounted to the rear panel  10   b  of the instrument compartment  14 . 
     A lower panel  18 , consisting of the lower portion of the instrument compartment  14 , is mounted to the front and rear panels  10   a  and  10   b  using a plurality of screws. A fan motor assembly  15 , for both radiating the heat of the electronic equipment and exhausting the smoke of the cooking cavity into the atmosphere, is mounted in such a manner that the fan motor assembly  15  is spaced apart from the right-side portion of the magnetron  16  by a predetermined gap. In addition, a condenser  19  is mounted in the instrument compartment  14 , while an exhaust channel  18   a  for forming a separated exhaust passage, is formed on the right-side portion of the lower panel  18  as shown in FIG.  1 . 
     As mentioned above, after the electronic equipment is embedded in the instrument compartment  14 , the electronic equipment is covered with an air guide plate  17  so that the exhaust passage is formed so as to connect the exhaust channel  18   a  to the air duct  20 . That is, the right-side portion of the instrument compartment  14 , corresponding to the exhaust channel  18   a  of the lower panel  18 , is covered with the air guide plate  17 , thereby forming the right-side portion of the instrument compartment  14  into the exhaust passage. Preferably, the guide plate  17  has an almost L-shaped cross-section. 
     An exhaust motor  22  is mounted around the rear portion of the air duct  20 . The exhaust motor  22  serves to generate an air current at the exhaust passage, which communicates with a base panel  30  of the microwave oven, a part of the instrument compartment  14  and the rear portion of the air duct  20 . An air intake port  24  is formed at the front side of the air duct  20  so that air is introduced into the interior of the instrument compartment  24  by the fan assembly  15  as described below. 
     FIGS. 2 and 3 are sectional views illustrating the mount construction of the conventional microwave oven shown in FIG.  1 . 
     As shown FIG. 2, the fan assembly  15 , serving to generate the air current, is mounted between the magnetron  16  and the high voltage transformer  11  at the intermediate height of the instrument compartment  14 . In addition, as shown FIG. 3, the fan assembly  15  is mounted at a position spaced apart from the right portion of the magnetron  16  so as to generate the air current for cooling the electronic equipment. 
     That is, the air is introduced into the cooking cavity  12  through the air intake port  24  by the fan assembly  15 . The air, passed through the fan assembly  15 , is separated into two air currents. The first air current flows toward the magnetron  16  mounted to the lower panel  18 , while the second air current flows toward the transformer  11 , mounted to the rear panel  10   b  of the instrument compartment  14 . Thus the electronic equipment is cooled by the introduction of the air current. Thereafter, such an air current is introduced into the cooking cavity  12  through a vent hole  12   b  formed on one sidewall  12   a  of the cavity  12 . Subsequently, the air current is exhausted with the air of the cavity  12  into the atmosphere through the other side wall of the cavity  12  or a vent hole formed on the top portion of the cooking cavity  12 . 
     However, such a conventional construction of the electronic equipment in the microwave oven has problems as described below. 
     The mounting positions of both the magnetron  16  and the high voltage transformer  11  are different from each other, when viewed from the position of the fan assembly  15 . That is, as shown FIG. 2, the magnetron  16  is mounted to the lower panel  18 , while the transformer  11  is mounted to the rear panel  10   b  of the instrument compartment  14 . Thus, the amount of air current introduced for the magnetron  16  and the transformer  11  is insufficient because the air is separately introduced to both the magnetron  16  and the transformer  11 . Also, when the air is introduced to both the magnetron  16  and the transformer  11 , the direction of the air current has to be changed so as to have a predetermined angle to cool both the magnetron  16  and the transformer  1 . Therefore, the cooling efficiency of the fan assembly  15  is reduced. 
     In addition, the fan assembly  15  is spaced apart from the air intake port  24  of the air duct  20 . That is, the air passage, connecting the air intake port  24  to the fan assembly  15 , is bent at an angle of 90°. Thus, the blowing force of the fan assembly  15  is reduced by the distance between the fan assembly  15  and the intake port  24 . Also, due to the complexity of an intake air course, the energy of the air current is reduced during the flowing of the air. Therefore, in order to intake a sufficient amount of air, the blowing force of the fan assembly  15  has to be increased. However, it is difficult to increase the blowing force of the fan assembly in the instrument compartment due to a limited area. 
     Also, in the fan assembly  15 , a fan cover  15   a  has to be formed into a specifically-bent shape suitable for introducing the cooling air into both the magnetron  16  and the transformer  11 . Therefore, the construction of the fan assembly  15  is complicated. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made with the above problems occurring in the conventional art in mind, and an object of the present invention is to provide a cooling structure for ventilation-hooded microwave ovens, which effectively cools electronic equipment in an instrument compartment. 
     In order to accomplish the above and other objects, the present invention provides a cooling structure for ventilation-hooded microwave ovens, comprising: an instrument compartment provided at a position spaced apart from a cooking cavity; a first electronic equipment piece mounted to the upper portion in the instrument compartment; a second instrument equipment piece mounted to the lower portion in the instrument compartment; and a fan assembly mounted in the instrument compartment at a position above the first electronic equipment piece, thus allowing an air current from the fan assembly to cool the first and second electronic equipment pieces. 
     This cooling structure further comprises guide means for guiding the air current to the first electronic equipment piece. Such guide means can include an air current guide for guiding the air current to the first electronic equipment piece. 
     The air current guide comprises vertical and horizontal parts, the vertical part downwardly extending from a mount opening formed on an air duct, and the horizontal part extending from one end portion of the vertical part so as to introduce the air current to the first electronic equipment piece. 
     The first and second electronic equipment pieces are mounted to the front position of the instrument compartment, and an air guide plate, having a plane shape, is mounted to the rear position of the instrument compartment, thus forming an exhaust passage between the air guide plate and a rear panel of the instrument compartment. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above objects, and other features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is an exploded perspective view of a conventional ventilation-hooded microwave oven for OTRs; 
     FIG. 2 is a longitudinal sectional view of the microwave oven in FIG. 1; 
     FIG. 3 is a horizontal sectional view of the microwave oven in FIG. 1; 
     FIG. 4 is an exploded perspective view of a ventilation-hooded microwave oven for OTRs in accordance with the preferred embodiment of the present invention; 
     FIG. 5 is a longitudinal cross-sectional view of a microwave oven in accordance with the present invention; 
     FIG. 6 is a horizontal sectional view (topview) of a microwave oven in accordance with the present invention; 
     FIG. 7 is a perspective view of an air duct of the microwave oven in accordance with the present invention; and 
     FIG. 8 is a view illustrating the flow of an air current in a microwave oven in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
     FIG. 4 is a view illustrating the construction of a microwave oven in accordance with the present invention. 
     In FIG. 4, an instrument compartment  104  is formed on the right position of a cooking cavity assembly  100 . The instrument compartment  104  is separated from a cooking cavity  102  by a cavity wall  105 . Also, a vent hole (not shown) is formed on the cooking cavity wall  105 , while the instrument compartment  104  communicates with the cooking cavity  102  by the vent hole. A lower panel  120 , including of the lower portion of the instrument compartment  104 , is mounted to the front and rear panels  107  and  108  of the compartment  104  by a plurality of screws. 
     The electronic equipment in the instrument compartment  104  is briefly described below. 
     A magnetron  124 , used for generating microwaves, is supported by the right end of the upper portion  106  of the cooking cavity  102  (FIG.  5 ), when the upper portion of the instrument compartment  104  is mounted to the cooking cavity  102 . Thus, due to such a magnetron  124 , the invention remarkably improves the space utilization of the compartment  104  in comparison with the instrument compartment according to the conventional art. 
     The electronic equipment, including such as a high transformer  125  and a condenser  123  for supplying a high voltage to the magnetron  124 , is mounted to the lower panel  120  by threading the screws through a plurality of screwing holes formed on the panel  120 . In addition, as shown FIG. 5, the electronic equipment for generating the microwaves is mounted to both the upper portion  106  of the cooking cavity  102  and the lower portion  120  of the instrument compartment  104 . Thus, such electronic equipment is effectively cooled by a fan assembly  114 , which is mounted to an upper air duct  110  as described below. 
     In addition, such electronic equipment is located at the front position of the instrument compartment  104 , while an exhaust passage A is formed at the rear position of the compartment  104  by an air guide plate  126  as shown in FIG.  6 . Such an exhaust passage A serves to exhaust smoke, generated from a gas oven, into the atmosphere by an exhaust motor mounted to the air duct  120 . That is, the electronic equipment, including such as a magnetron, is mounted at the front position of the instrument compartment  104 , while the exhaust passage A is formed between the air guide plate  126  and the rear panel  108  of the compartment  104 . 
     A fan assembly  114 , serving to cool the electronic equipment and to exhaust the smoke of the cavity  102  into the atmosphere, is mounted to the right-side position of the air duct  110 . That is, the fan assembly  114  is positioned above the electronic equipment in the instrument compartment  104 . Thus, the electronic equipment, mounted to the lower portion of the compartment  104 , is effectively cooled by the fan assembly  114 . 
     As shown in FIG. 7, the fan assembly  114  of this invention is mounted to the right-side position of the air duct  110 , thus downwardly introducing air into the compartment  104 . Also, as mentioned above, the magnetron  124  is mounted in the compartment  104  at a position close to the fan assembly  114  because the magnetron  124  is mounted to the upper portion  106  of the cooking cavity  102  as shown in FIG.  5 . 
     A support  113   a  for supporting the fan assembly  114  is formed on the upper portion of a mount opening  113 , which is formed on the right-side portion of the air duct  110 . Also, a fan  114   b  is mounted to the lower portion of a fan motor  114   a,  while the fan motor  114   a  is mounted to the support  113   a.  An air current guide  116 , downwardly extending from the mount opening  113 , is integrally formed at the mount opening  113 . Thus, the air current, intaken by the fan  114   b,  is introduced to both the magnetron  124  an d the lower potion of the mount opening  113  by the air current guide  116 . 
     As shown in FIGS. 7 and 8, the guide  116  has vertical and horizontal parts  116   a  and  116   b.  The vertical part  116   a  downwardly extends along the edge portion of the mount opening  113  by a predetermined distance of 40 to 50 mm, while the horizontal part  116   b  is horizontally or perpendicularly bent from the vertical part  116   a.  The horizontal part  116   b  serves to guide the air current to the magnetron  124  located at a position opposite to the horizontal part  116   b.  Such vertical and horizontal parts  116   a  and  116   b  are formed on the lower edge portion of the mount opening  113 . Also, the length of the vertical and horizontal parts  116   a  and  116   b  may be changed so as to more effectively guide the introduced air current to the magnetron  124  and the transformer  125 . Thus, the air is properly and sufficiently introduced by the rotation of the fan  114   b.    
     Due to the air current guide  116  formed at the edge portion of the mount opening  113 , one part of the air current is introduced along the vertical part  116   a  to the magnetron  124  after meeting the horizontal part  116   b.  The other part of the air current is introduced into the lower potion of the mount opening  113  without meeting the horizontal part  116   b.    
     The flowing flow of the air current in the microwave oven of this invention is described below. 
     When the microwave oven is turned on, the fan assembly  114 , mounted to the air duct  110 , actuates. Thus, the fan  114   b  is rotated. Due to the rotation of the fan  114   b,  the air current for cooling the electronic equipment in the instrument compartment  104  is generated at the lower portion of the fan  114   b.    
     Such an air current is primarily introduced into the lower portion of the mount opening  113  of the air duct  110 . Then, the air current around the edge portion of the mount opening  113 , meets and guided by the horizontal part  116   b  of the guide  116 . This air current is, thereafter, circularly rotated along the vertical part  116   a  from the horizontal part  116   b  of the guide  116  due to the inertia force of the fan  114   b.  Thereafter, the air current passes through the mount opening  113 , at which the guidance of air may be terminated. The air current is then introduced to the magnetron  124  because the magnetron  124  is located at the upper position of the end portion of the guide  116 . Such a flow of the air current is depleted in e.g., FIG.  5 . 
     In addition, the air current around the central portion of the mount opening  113  is introduced into the lower portion of the mount opening  113 , thereby cooling the electronic equipment including, such as the high transformer  125  and condenser  123  mounted to the lower panel  120 . 
     The air current, passed by the above electronic equipment, is introduced into the cooking cavity  102  through a first vent hole (not shown) formed on one side wall  105  of the cavity  102 . Thereafter, such an air current is exhausted into the atmosphere through a second vent hole formed on the other side wall of the cooking cavity  102  along with the smoke generated from the cavity  102  during a cooking process. 
     As mentioned above, the fan assembly  114  is mounted to the air duct  110 , which corresponds to the upper portion of the instrument compartment  104 . Thus, the air current, generated by the fan assembly  114 , is introduced downwardly into the lower portion of the instrument compartment  104 . Such an air current is introduced to the magnetron  124  by the vertical and horizontal parts  116   a  and  116   b  of the guide  116 , and into the lower panel  120 . Also, the air current guide  116  may be altered without affecting the functions and operations of this invention, to guide the introduced air current to the magnetron  124  mounted to the upper portion  106  of the cooking cavity  102 . 
     In accordance with another embodiment of the present invention, a guide member for guiding the air current may be mounted in the instrument compartment  104  so as to guide the air current generated by the fan assembly  114  to the magnetron  124 . That is, the guide member can be mounted to the lower portion of the air duct  110  in such a manner that the air current meets the guide member and is introduced to the magnetron  124  under the guide of the guide member. 
     In addition, the position of the magnetron  124  may be directly exchanged with that of the high voltage transformer  125 . That is, even when one piece of the electronic equipment (e.g., the magnetron  124  or the transformer  125 ) is mounted to the upper portion of the instrument compartment  104  and another piece of electronic equipment is mounted to the lower panel  120 , the air current is concurrently and effectively introduced to all pieces of the electronic equipment. 
     As mentioned above, the cooling structure for ventilation-hooded microwave ovens in accordance with the present invention is provided with a cooling fan mounted to the upper portion of an instrument compartment, thereby allowing the air current to be introduced to one piece of the electronic equipment (a magnetron,etc.) mounted to the upper portion of the instrument compartment and to another piece of the electronic equipment mounted to the lower panel. As a result, the fan for cooling the different pieces of the electronic equipment is mounted at a position at which an air current is easily introduced from the atmosphere. Thus, the cooling efficiency of the microwave oven is increased by the operation of the fan assembly. 
     In addition, even when the rotation speed of the fan is reduced, the cooling effect of the electronic equipment is maintained. Also, the intake force of the air is improved, thereby minimizing operational noises and vibrations according to both the rotation of the fan and the flow of the air current. 
     The electronic equipment may be mounted to the front portion of the instrument compartment, while the rear portion of the compartment may be formed into an exhaust passage by the air guide having a plane or other shape. As a result, the construction of the exhaust passage, serving the ventilation hood in the microwave oven, is simplified. 
     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.