Patent Publication Number: US-6906294-B2

Title: Composite cooking apparatus and method of controlling the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Application No. 2003-29103, filed May 7, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates, in general, to a composite cooking apparatus and method of controlling the same, which performs heating using a plane heater and/or induction heating using high frequency current. 
     2. Description of the Related Art 
     Generally, a cooking apparatus which heats and cooks food using a plane heater or other electric heater is advantageous in that it is not relatively affected by the type and material of a container, but it is disadvantageous in that thermal efficiency is poor. A method of heating using a heating element, such as a plane heater, is disclosed in Japanese Patent Laid-open Publication No. 11-121156. 
     In a cooking apparatus which performs induction heating using high frequency current, thermal efficiency thereof is better than that of a cooking apparatus using an electric heater, but heating may not be performed or thermal efficiency thereof is poor in the case where a glass container or aluminum container is used. Thus, the use of an electrically conductive container is required to enable induction heating to be efficiently performed. 
     As described above, the cooking apparatus employing a single type of heat source is problematic in that it is restricted by a cooking container if thermal efficiency is to be high, and thermal efficiency is low if it is not restricted by a cooking container. 
     Further, in the case where a single type of heat source is used, an output power control function is insufficient, such as the output power control function being performed only within a limited range, thus causing the dissatisfaction of a user. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an aspect of the present invention to provide a composite cooking apparatus and method of controlling the same, which improves thermal efficiency at the time of heating and cooking, and it is not restricted by a cooking container. 
     It is another aspect of the present invention to provide a composite cooking apparatus and method of controlling the same, which may perform a normal cooking mode in which cooking is carried out at normal output power using a single type of heat source, and a rapid cooking mode in which cooking is carried out at high output power using a composite heat source including different types of heat sources. 
     Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
     The foregoing and/or other aspects of the present invention are achieved by providing a composite cooking apparatus including two different heat sources to heat food in a cooking container, and a controller to control operations of heating and cooking the food by operating any one or both of the two heat sources according to an operating mode. 
     The heat sources are a plane heater and an induction heater, respectively. 
     The composite cooking apparatus further includes a heat resistant glass plate to allow the cooking container to be seated thereon, and the plane and induction heaters are mounted below the heat resistant glass plate. 
     The composite cooking apparatus further includes an air discharge duct to discharge heated air to outside of the composite cooking apparatus. The plane heater is mounted on a top of the air discharge duct, and the induction heater is mounted below the air discharge duct. 
     The composite cooking apparatus further includes a cooling fan motor mounted in the air discharge duct to forcibly blow air heated by heat radiated from the plane heater. 
     The composite cooking apparatus further includes a heat insulating material mounted to come into contact with the plane heater in a face-to-face manner to block heat radiated from the plane heater. 
     The heat insulating material is made of heat resistant material. 
     The heat insulating material is heat resistant up to a temperature of approximately 500° C. 
     The heat insulating material is made of material capable of transmitting a magnetic field. 
     The controller operates both the plane and induction heaters if an operating mode to shorten a cooking time is set. 
     The composite cooking apparatus further includes a power supply unit to supply driving power to the plane heater, an inverter to supply driving power of a predetermined frequency to the induction heater, and a current detecting unit to detect current of the inverter. 
     The controller determines a heat source suitable for material of the cooking container depending on the current detected by the current detecting unit. 
     The controller determines that the cooking container is suitable in induction heating if the detected current is equal to or greater than a set value, while the controller determines that the cooking container is suitable in plane heating if the detected current is less than the set value. 
     The foregoing and/or other aspects of the present invention are achieved by providing a method of controlling a composite cooking apparatus, the composite cooking apparatus having a plane heater and an induction heater, the method including setting a cooking command, and heating and cooking food in a cooking container by operating any one or both of the two heaters according to the set cooking command. 
     The composite cooking apparatus control method further includes detecting current of an inverter which supplies driving power to the induction heater, and heating and cooking the food using a heater suitable for the cooking container depending on the detected current. 
     The composite cooking apparatus control method further includes heating food in the cooking container in an induction heating manner if the detected current is equal to or greater than a set value, while heating the food in the cooking container in a plane heating manner if the detected current is less than the set value. 
     The composite cooking apparatus control method further includes discharging air heated by the heater to outside of the composite cooking apparatus by driving a cooling fan motor at the time of heating and cooking using the heaters. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a view showing an example in which a composite cooking apparatus, according to an embodiment of the present invention, is used; 
         FIG. 2  is a sectional view of the composite cooking apparatus of  FIG. 1 , according to an embodiment of the present invention; 
         FIG. 3  is a sectional view of the composite cooking apparatus of  FIG. 1 , according to another embodiment of the present invention; 
         FIG. 4  is a control block diagram of the composite cooking apparatus of the present invention; and 
         FIG. 5  is a flowchart of a method of controlling the cooking apparatus of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. 
       FIG. 1  is a view showing an example in which a composite cooking apparatus  100 , according to the present invention, is used.  FIG. 2  is a sectional view of the composite cooking apparatus  100 , according to an embodiment of the present invention. 
     The composite cooking apparatus  100  is capable of cooking using a composite heat source, and is arranged on a top of an auxiliary table  300  which provides a receiving space that receives kitchen utensils. The composite cooking apparatus  100  is provided with a cooking command setting unit  110  arranged on a front thereof to set cooking commands using buttons and knobs. A user may set a desired cooking mode using the cooking command setting unit  110  at the time of heating and cooking. 
     Heat resistant glass plates  120  are mounted on an upper casing  101  of the composite cooking apparatus  100  to allow a cooking container  103  to be seated thereon to perform heating and cooking, and outlets  105  are formed in a back of the composite cooking apparatus  100  to discharge heated air. 
     The composite cooking apparatus  100  of the present invention may perform a heating operation using a plane heater and an induction heating operation using high frequency current together. As shown in  FIG. 2  illustrating a sectional view taken along line A—A, the composite cooking apparatus  100  has a plane heater  140  and an induction heater  170  arranged below each of the heat resistant glass plates  120 , as a composite heat source. The plane heater  140  is mounted on a top of an air discharge duct  102 , and the induction heater  170  is mounted below the air discharge duct  102 . 
     Respective heat sources are independently supplied with driving power. A power supply unit  130  supplies driving power (Alternating Current (AC) or Direct Current (DC) power) to the plane heater  140 . The induction heater  170  includes a working coil  172  and a support  171 . The working coil  172  arranged on the support  171  generates high frequency current depending on driving power of a predetermined frequency, supplied from an inverter  160 , and heats food in the cooking container  103  using the high frequency current in an induction heating manner. When the induction heating is performed, a conductive container is used as the cooking container  103 . 
     When the plane heater  140  is operated, the plane heater  140  heats the cooking container  103  seated on the heat resistant glass plate  120  in a plane heating manner, and downwardly radiates heat. Preferably, the working coil  172  is mounted to be spaced apart from the plane heater  140 . More preferably, a cooling fan motor  150  is disposed at a portion of the air discharge duct  102  and is driven under the control of a controller, which will be described later, to allow heated air existing in an air path  104  to be forcibly blown, thus preventing the deterioration of the working coil  172  and consequently increasing a life span thereof. 
     One end of the air discharge duct  102  is connected to the outlets  105 , and heated air is guided to the outlets  105  through the air discharge duct  102  to be discharged to the outside of the composite cooking apparatus when the cooling fan motor  150  is operated. 
     In a normal cooking mode, any one of the two heat sources  140  and  170  may be independently operated to perform heating and cooking, while, in a rapid cooking mode, both the heat sources  140  and  170  may be used to perform heating and cooking. This rapid cooking mode is mainly used when a cooking time is required to be shortened. In the rapid cooking mode, the cooling fan motor  150  is preferably driven together with the two heat sources  140  and  170 . 
       FIG. 3  is a sectional view of a composite cooking apparatus, according to another embodiment of the present invention. The same reference numerals are used to designate components performing the same functions throughout different drawings. 
     Referring to  FIG. 3 , the composite cooking apparatus  100  further includes a heat insulating material  180  mounted below the plane heater  140  to block heat radiated from the plane heater  140 . 
     The heat insulating material  180  comes into contact with the plane heater  140  in a face-to-face manner, so the heat insulating material  180  should be made of material having excellent heat resistance and is capable of transmitting a magnetic field generated by the induction heater  170 , that is, high frequency waves. In this embodiment, a heat resistance temperature is approximately 500° C., but it is not limited to 500° C. 
       FIG. 4  is a control block diagram of the composite cooking apparatus of the present invention. 
     The composite cooking apparatus of the present invention includes a controller  190  which controls an entire operation of heating and cooking food using the composite heat source. An input terminal of the controller  190  is connected to the cooking command setting unit  110  which sets cooking commands of the user, and a current detecting unit  200  which detects current of the inverter  160 . An output terminal of the controller  190  is connected to the power supply unit  130  which supplies driving power to the plane heater  140 , the inverter  160  which supplies driving power of a predetermined frequency to the working coil  172 , and a cooling fan motor driving unit  210  which drives the cooling fan motor  150 . 
     The controller  190  performs the normal cooking mode or rapid cooking mode according to a cooking command received from the cooking command setting unit  110 . The normal cooking mode is an operating mode in which the cooking container  103  is seated on the heat resistant glass plate  120  to perform heating and cooking using any one of the two heat sources, that is, the plane heater  140  or the working coil  172 . In this normal cooking mode, if the material of the cooking container  103  is not suitable for induction heating, heating and cooking by the plane heater  140  are automatically performed, while if the material of the cooking container  103  is an electrically conductive metal, the induction heating is automatically performed. 
     The controller  190  determines whether the material of the cooking container  103  is suitable for induction heating depending on current detected by the current detecting unit  200 . That is, when a cooking command is set, the controller  190  controls the inverter  160  to supply driving power of a predetermined frequency to the working coil  172 , so high frequency current is generated by the working coil  172 . If the current detected by the current detecting unit  200  varies to be equal to or greater than a certain value, the controller  190  determines that the cooking container  103  is made of electrically conductive material and is suitable for the induction heating. On the contrary, if the current detected by the current detecting unit  200  is less than the certain value, the controller  190  determines that the cooking container  103  is not made of electrically conductive material and is not suitable for the induction heating. 
     If the rapid cooking mode is set by the user, the controller  190  simultaneously operates both the plane heater  140  and the working coil  172  to heat and cook food in the cooking container  103 . Further, the composite heat source including the two heat sources is used to perform heating and cooking at high output power, thus shortening a cooking time. 
     A method of controlling the composite cooking apparatus of the present invention, having the above construction, is described in detail with reference to the attached drawings. 
     First, the user seats the cooking container  103  on the heat resistant glass plate  120 , and then sets a desired cooking command through the cooking command setting unit  110  in operation  1 . 
     If the cooking command is set by the user, the controller  190  controls the inverter  160  to supply driving power of a predetermined frequency to the working coil  172  to perform induction heating. Thereafter, the controller  190  determines whether the cooking container  103  is a metal container, that is, whether the cooking container  103  is made of electrically conductive material, depending on current detected by the current detecting unit  200  in operation  10 . If it is determined that the cooking container  103  is not a metal container, the controller  190  operates the plane heater  140  to heat and cook food in the cooking container  103  in operation  50 . At this time, the controller  190  controls the cooling fan motor driving unit  210  to drive the cooling fan motor  150  to perform an operation of discharging heated air through the outlets  105 . The operation  50  is suitable for the normal cooking mode, but it may be performed even when the user seats the cooking container  103 , not made of metal material, on the heat resistant glass plate  120  and sets the rapid cooking mode due to the carelessness of the user. 
     If it is determined that the cooking container  103  is a metal container in operation  10 , the controller  190  determines whether the rapid cooking mode for heating and cooking food at high output power to shorten a cooking time is set in operation  20 . If it is determined that the rapid cooking mode is not set, the controller  190  controls the inverter  160  to supply driving power of a predetermined frequency to the working coil  172  to heat food in the cooking container  103  in the induction heating manner in operation  30 . At this time, the controller  190  controls the cooling fan motor driving unit  210  to drive the cooling fan motor  150  to perform an operation of discharging heated air through the outlets  105 . If it is determined that the rapid cooking mode is set in operation  20 , the controller  190  supplies driving power of a predetermined frequency to the working coil  172  through the inverter  160 , and supplies driving power to the plane heater  130  through the power supply unit  130 , thus heating and cooking food in the cooking container  103  using both the two heat sources  140  and  170  in operation  40 . At this time, the controller  190  controls the cooling fan motor driving unit  210  to drive the cooling fan motor  150  to perform an operation of discharging heated air through the outlets  105 . 
     As is apparent from the above description, the present invention provides a composite cooking apparatus and method of controlling the same, which improves thermal efficiency and is not restricted by a cooking container by using a composite heat source at the time of heating and cooking food, thus increasing the convenience in use. Further, the present invention is advantageous in that it may perform heating and cooking using a heat source suitable for material of a cooking container, and perform cooking at high output power using the composite heat source including two heat sources to shorten a cooking time in the case where a rapid cooking mode is set. 
     Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.