Patent Publication Number: US-6218651-B1

Title: Microwave oven

Description:
CLAIM OF PRIORITY 
     This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from my application MICROWAVE OVEN filed with the Korean Industrial Property Office on Nov. 17, 1999 and there duly assigned Ser. No. 51099/1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a microwave oven, and more particularly, an improved microwave oven having a cooking chamber, a fan housing attached to the cooking chamber, and a convection heater mounted on an air passageway formed between the cooking chamber and the fan housing. 
     2. Description of the Related Art 
     A microwave oven having a convection heater has been used for efficiently cooking food placed in a cooking chamber while the food is cooked by microwaves. Typically, the convection heater is mounted on a sidewall of a fan housing attached to the cooking chamber. For example, a conventional microwave oven shown in FIGS. 1 and 2 includes a main body  101  and a cooking chamber  103  formed in the main body  101 . In the front of the main body  101  are provided a door  105  opening and closing the cooking chamber  103  and a control panel  107  operating the microwave oven. In the rear of the control panel  107  is formed a component chamber in which a number of components operating cooking functions of the microwave oven are installed. 
     On the bottom of the cooking chamber  103 , a circular tray  109  on which the food is put is rotatably installed. The circular tray  109  is rotated by a driving motor not shown. A fan housing  130  is formed at the rear of the cooking chamber  103  and between a partition  110  and a heater casing  131 . In the fan housing  130  are installed a convection heater  121  generating heat by means of an external power supply and a ventilator sending air heated by the convection heater  121  into the cooking chamber  103 . 
     On the partition  110  are formed a number of air suction holes  111  and air discharge holes  123  circulating air heated by the convection heater  121  between the cooking chamber  103  and the fan housing  131 . The air suction holes  111  are formed in the central area of the partition  110  and are in communication with the fan housing  130 . The air discharge holes  123  are formed along the circumferential area of the partition  110  and are in communication with the fan housing  130 . The convection heater  121  having a form of loop mounted adjacent to the air discharge holes  123  on the partition  110  and is fixed on the back face of the partition  110  by a plurality of brackets  135 . The fan  133  mounted on heater casing  131  is disposed in the rear area of the convection heater  121  and adjacent to the air suction holes  111  formed on the partition  110  to suck the air from cooking chamber  103  into the inside of the fan housing  130  through the air suction holes  111  and blow the air sucked into the fan housing  130  toward the air discharge holes  123 . 
     With this configuration, when the microwave oven operates, the convection heater  121  heats the air within the fan housing  130 . Then, the fan  133  blows the heated air in the radial direction. The heated air in the fan housing  130  is discharged into the cooking chamber  103  through the air discharge holes  123 , and thereby cooking the food in the cooking chamber  103 . The air blown into the cooking chamber  103  returns to the fan housing  130  through the air suction holes  111  by the suction force of the fan  133 . The returning air is heated by the convection heater  121  and transferred into the cooking chamber  103  by the fan  133 , thereby forming air circulation. 
     However, since the convection heater is installed in the fan housing isolated from the cooking chamber and is not located on an air passageway, the heat energy of the convection heater is consumed to increase temperature of the inner side of the fan housing and the remaining heat energy is consumed to heat the air blown into the cooking chamber through the air discharge holes. Thus, there occurs a loss of heat by the amount of the heat which is used to heat the fan housing, thereby lowering efficiency of cooking in the microwave oven. Furthermore, to prevent heat from being transferred into a driving motor of the fan and an electric wire, etc., and being emitted outside of the cooking chamber and the fan housing, an insulating member is required around the convection heater, thereby increasing the cost of production. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide a microwave oven able to reduce loss of heat. 
     It is another object to provide a microwave oven able to improve the efficiency of cooking. 
     It is also an object to provide a microwave oven able to reduce the cost of production. 
     These and other object may be achieved by providing a microwave oven including a cooking chamber, a fan housing, both of which are isolated by a partition, and a heater housing depressed from said partition toward the fan housing and having at least one air discharge hole formed on a side of the heater housing. The air discharge hole communicates with the fan housing. A convection heater is housed in the heater housing, and a fan installed in the fan housing blows air in said fan housing into the cooking chamber through the air discharge holes and the convection heater. At least one air suction hole is formed in a central area of the partition, and the heater housing is positioned around the air discharge hole. The partition is a rear wall of the cooking chamber. The heater housing has a groove section, and the air discharge holes are formed on a sidewall of the groove section of the heater housing toward the fan. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the invention, and may of the attendant advantages, thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein: 
     FIG. 1 is a perspective view of an embodiment of a conventional microwave oven; 
     FIG. 2 is a cross-sectional view of a fan housing of FIG.  1 . 
     FIG. 3 is a perspective view of a microwave oven according to the present invention; 
     FIG. 4 is a perspective view showing partially rear area of a cooking chamber and inside of a fan housing of FIG. 3; and 
     FIG. 5 is a cross-sectional view of the fan housing and the cooking chamber; 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 3 through 5, the microwave oven according to the principle of the present invention has a main body  1  having a cooking chamber  3  into which food to be cooked is put. In the front of the main body  1  are provided a door  5  opening and closing the cooking chamber  3  and a control panel  7  operating the microwave oven. In the rear of the control panel  7  is formed a component chamber in which a variety of components operating cooking processes of the microwave oven are installed. On the bottom of the cooking chamber  3 , a circular tray  9  on which the food is put is rotatably installed. The circular tray  9  is rotated by a driving motor not shown. A fan housing  30  is formed at the rear of the cooking chamber  3  and between a partition  10  and a heater casing  31 . On a backside of the fan housing  30  is installed a fan  33  blowing heated air into the cooking chamber  3 . 
     A plurality of air suction holes  1   1  are formed in the central area of the partition  10  and are in communication with the fan housing  30 . A heater housing  20  is formed along the circumferential area of the partition  10  and around the air suction holes  11 . The heater housing  20  having a form of loop is depressed toward the fan housing  30 . Preferably, the heater housing  20  is depressed from the planar surface of the partition  10  to form a groove section. 
     A convection heater  21  having a form of loop is housed in the heater housing  20  along the longitudinal direction thereof. On a sidewall of the groove section of the depressed heater housing  20  are formed a plurality of air discharge holes  23  communicating with the fan housing  30 , along the longitudinal direction of the heater housing  20 . 
     With this configuration, when the microwave oven operates, the convection heater  21  housed in the heater housing  20  heats air blown from the fan housing  30  into the cooking chamber  3 . Then, the fan  33  installed in the fan housing  30  blow the heated air in the radial direction of the fan  33  and toward the convection heater  21 . 
     The heated air blown by the fan  33  flows into the cooking chamber  3  through the air discharge holes  23  formed on the sidewall of the heater housing  20 . The heat generated by the convection heater  21  housed in the heater housing  20  can be transferred directly to the cooking chamber  3  by the heated air passing through the air discharge holes  23  and the convection heater  21 , thereby reducing loss of heat at minimum. 
     The air in the cooking chamber  3  returns to the fan housing  30  through the air suction holes  11  by the suction force of the fan  33 , thereby forming an air circulation between the cooking chamber  3  and the fan housing  30 . The heat transferring operation from the convection heater  21  to the cooking chamber  103  is repeated by the air circulation, thereby cooking the food. 
     As described above, since the convection heater  21  is installed in the heater housing  20  which is formed on the partition  10  and depressed toward the fan housing  30 , loss of heat generated by the convection heater  21  can be effectively decreased. Further, since the convection heater is installed inside the cooking chamber, there is no need to install an insulation member separately in the fan housing, thereby lowering cost of production. 
     In the embodiment according to the principle of the present invention described above, the heater housing is formed in the shape of loop in the circumferential area of the partition, but the heater housing may be formed in any manner, for example, in both upper and lower portions of the cooking chamber, or both left and right sides of the wall of the cooking chamber or either upper or lower portions, or either left or right side of the wall of the cooking chamber. 
     According to the present invention, there is provided a microwave oven in which loss of heat is reduced, thereby increasing the efficiency of cooking, and reducing the cost of production. 
     Although the present invention has been described in connection with a preferred embodiment thereof, it will be appreciated by those skilled in the art that additions, modifications, substitutions and deletions not specifically described may be made without departing from the spirit and scope of the invention as defined in the appended claims.