Patent Publication Number: US-8981267-B2

Title: Cooktop heating element with improved connection structure

Description:
This application claims the benefit of Korean Patent Application No. 10-2007-0022840 filed on Mar. 8, 2007, the entirety of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     This relates to a heating device, and more specifically to a heating device having improved heat resistance. 
     2. Background 
     Generally, a ramp heater is a heating device that generates heat through resistance generated by a heating element installed in a closed container. These types of heaters often experience overheating and/or damage at high power levels, sometimes due to the dissimilar materials used in their fabrication. Additionally, fabrication can be complex due to the interaction of the various parts and materials used. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein: 
         FIG. 1  is a cross-sectional view of an exemplary heating device; 
         FIG. 2  is an enlarged cross-sectional view of the exemplary heating device shown in  FIG. 1 ; 
         FIG. 3  is a perspective view of an exemplary cooking apparatus to which a heating device as embodied and broadly described herein may be applied; 
         FIG. 4  is an exploded perspective view of a burner of the exemplary cooling apparatus shown in  FIG. 3 ; 
         FIG. 5  is a cross-sectional view of a heating device in accordance with a first embodiment as broadly described herein; 
         FIG. 6  is a cross-sectional view of an alternative coupling used in the heating device shown in  FIG. 5 ; 
         FIG. 7  is a cross-sectional view of a heating device in accordance with a second embodiment as broadly described herein; 
         FIG. 8  is a cross-sectional view of a heating device in accordance with a third embodiment as broadly described herein; and 
         FIG. 9  is a cross-sectional view of a heating device in accordance with a fourth embodiment as broadly described herein. 
     
    
    
     DETAILED DESCRIPTION 
     The exemplary heater shown in  FIG. 1  may include a heating element  2  that generates heat by resistance when an external voltage is applied, a closed container  3  having the heating element  2  installed therein, and a conductor  1  through which voltage may be applied to the heating element  2 . The conductor  1  may include, for example, an outer spring and an inner spring, with the heating element  2  positioned therebetween. 
     External power, in the form of, for example, electricity, may be applied to the heating element  2  through the conductor  1 . In certain embodiments, the conductor  1  may have a coil spring shape in order to maintain tension on the heating element  2 . Thus, the heating element  2  and the conductor  1  may form contacts at several points. 
     In certain embodiments, the electrical resistance of the heating element  2  may generally be greater than that of the conductor  1 . Accordingly, although the electrical resistances at all of the contact points of the conductor  1  and the heating element  2  may be substantially the same, the current passing a first contact point may be less than the current passing the next contact point, with the most current passing through a last contact point  2   a.    
     If a high power level is required for the heating element  2 , a large current may be applied to the heating element  2  through the conductor  1  to generate the desired power. However, in this instance, since a great amount of current would pass through the last contact point  2   a , the last contact point  2   a  would experience a dramatic temperature increase, causing possible damage to the heating element  2  or the conductor  1  at this point. This has even more impact in a structure having a heating element  2  and a conductor  1  made of dissimilar materials such as, for example, a heating element  2  made of a carbon material and a conductor made of a molybdenum material. 
     To improve thermal characteristics of the heater, the heating element  2  may be formed as a fiber such as, for example, a carbon fiber made of carbon material. However, a heating element  2  made of a carbon fiber material is flexible, similar to cloth. Thus, it may be difficult to insert such a flexible heating element  2  into the space between the outer spring and the inner spring of the conductor  1 . 
       FIG. 3  is a perspective view of an exemplary cooking apparatus to which a heating device as embodied and broadly described herein may be applied. This application of the heating device in a burner of a cooking apparatus it is exemplary in nature, and thus is not limited thereto, but can also be applied to numerous other devices, or alone, as appropriate. 
     The exemplary cooking apparatus may include a cooktop (C) provided with a plurality of burners  100 . An oven (O) may be opened and closed by a door d disposed below the cooktop (C). The oven (O) may include, for example, a heater and a magnetron (not shown in  FIG. 3 ) that heat a cooking room of the oven (O). A control panel (P) including a controller (not shown in  FIG. 3 ) may control the cooking apparatus. 
     A plate  110  may be provided on an upper surface of the cooktop (C). The plate  110  may be made of, for example, a ceramic material, or other material as appropriate, and may be provided with indicia, such as, for example an indicating line delineating an accurate position of the burners  100 . In alternative embodiments, the plate  110  may be transparent so that the burners  100  are visible therethrough. The plate  110  may be substantially planar for easy cleaning. 
     A plurality of burners  100  may be provided under the plate  110 . As shown in  FIG. 3 , the burners  100  may have different sizes so that food can be cooked using various sizes of vessels. For example, at least one of the burners  100  may be elongated so as to heat a long vessel. The sizes and shapes of the burners  100  may be different, while the structures thereof may be substantially the same. For example, as shown in  FIG. 4 , a burner  100  may include a heat-generating heating device  120 , and a reflecting plate  200  that reflects heat and light emitted by the heating device  120  to the plate  110 . 
     A heating device  120  in accordance with the embodiment shown in  FIG. 5  may include a heating element  40  that generates heat, an elastic conductive part  50  that supplies electricity to the heating element  40 , and a connector  60  provided between the elastic conductive part  50  and the heating element  40 . In certain embodiments, the heating element  40  may generate heat through electrical resistance. However, other means may also be appropriate, based on a particular application. 
     In certain embodiments fish trap type of a filament may be used as the heating element  40 , and the filament may be made of carbon. Other filament materials, such as, for example, tungsten, may also be appropriate. The heating element  40  may be installed in a quartz tube  70 . 
     The quartz tube  70  may be made of a chemically stabilized silicon dioxide SiO2, similar, for example, to that which is used in the semiconductor industry, requiring stability at high temperatures. More specifically, since softening of this type of quartz does not occur until approximately 1683° C., and a thermal expansion coefficient thereof is relatively small, a quartz tube  70  made of this type of stabilized SiO 2  is able to withstand rapid heating and cooling. Additionally, light in the ultraviolet region as well as the infrared region may be transmitted therethrough, and the quartz tube  70  provides a high degree of electrical isolation. 
     In certain embodiments, the connector  60  may be provided at both ends of the heating element  40  so as to fix the heating element  40  in place. The connector  60  may be made of an allotrope material having electrical properties similar to those of the heating element  40  in order to reduce contact resistance between the connector  60  and the heating element  40 . 
     When a number of atoms forming a particular molecule is different, or when a chemical composition is the same but an arrangement state and bonding mode of the atoms is different, the resulting material is referred to as an allotrope. An allotrope is essentially a single-element material made of the same element, but which differs in shape and properties. 
     If the heating element  40  is used at a low power level, such as, for example, 500 W, a corresponding amount of an applied voltage and current is low so that the material of the connector  60  is not particularly limited. However, if the heating element  40  is used at a high power level, such as, for example, above 3.0 kW, the contact resistance of the connector  60  with the heating element  40  may result in abnormal heat-generation. Thus, the connector  60  may be made of an allotrope, which is a material similar in electrical properties to the heating element  40 , to reduce or substantially eliminate the effects of the dissimilar materials in a high power, high heat environment. 
     In one embodiment, the connector  40  may be made of a graphite material, which is an allotrope of a heating element  40  made of carbon material. This arrangement may minimize contact resistance at the contact surface. In this instance, since the connector  60  is not a direct heating element, that is, an element having a high resistance, localized abnormal overheating does not occur between the connector  60  and the elastic conductive part  50 . 
     More particularly, a connector  60  made of graphite material may be heat-treated in a vacuum, and may be subject to a process that removes remaining moisture and other gas included in the graphite. The connector  60  made of graphite material may have a predetermined thickness to supplement mechanical strength and provide the desired electrical properties. 
     An elastic conductive part  50  may be coupled to the connector  60 . The elastic conductive part  50  may apply electricity to the heating element  40  through the connector  60 . The elastic conductive part  50  may have a predetermined elasticity so as to uniformly maintain tension on the heating element  40  so that the heating element  40  is tautly drawn in the inside of the quartz tube  70 . This may avoid contact between the heating element  40  and the tube  70  and subsequent localized burning/damage to the heating element  40  and/or tube  70 . 
     The connector  60  may include a first fixed portion  62  having a hollow formed therein, and a second fixed portion  64  separated from the first fixed portion  62 . In certain embodiments, the first fixed portion  62  may have a hollow cylindrical shape, and the second fixed portion  64  may have a solid, circular bar shape that may be inserted into the first fixed portion  62 . 
     In certain embodiments, a diameter of the hollow formed in the first fixed portion  62  may be greater than an outer diameter of the second fixed portion  64 . This allows the end of the heating element  40  to be inserted into a space formed between the first fixed portion  62  and the second fixed portion  64 . In this manner, the first fixed portion  62  and the second fixed portion  64  may be coupled in a shape-fitting form, allowing the heating element  40  to be fixed between the first fixed portion  62  and the second fixed portion  64 . 
     In certain embodiments, at least one of the inner surface of the first fixed portion  62  and the outer surface the second fixed portion  64  may be tapered. At least one of the inner circumference of the first fixed portion  62  or the outer circumference the second fixed portion  64  may be inclined, and the first fixed portion  62  and the second fixed portion  64  may be coupled by force fit, thereby making it possible to more firmly fix the heating element  40  in place therebetween. 
     The elastic conductive part  50  may be coupled to the end of the second fixed portion  64  opposite to the end which is contacted by the heating element  40 . The elastic conductive part  50  may be made of a wire material such as, for example, molybdenum Mo, or nickel Ni, and a portion of the elastic conductive part  50  may be bent in a spring shape and wound about the second fixed portion  64 . That is, a portion of the elastic conductive part  50  may have a certain degree of elasticity, like a spring, and thus elastically draw the second fixed portion  64  tight so that the heating element  40  coupled to the second fixed portion  64  is uniformly drawn and held taught, thereby maintaining an appropriate amount of tension. 
     As described above, if the second fixed portion  64  is solid, although the winding of the elastic conductive part  50  exerts a tightening force on the second fixed portion  64 , the risk of damage to the second fixed portion  64  is reduced. Additionally, when the heating element  40  and the connector  60  are coupled in this manner, assembly may be simplified by inserting the heating element  40  into the inner circumferential surface of the first fixed portion  62 , inserting one end of the second fixed portion  64  into the inner circumferential surface of the heating element  40 , and then press fitting the first fixed portion  62  into the second fixed portion  64 . 
     In the embodiment shown in  FIG. 6 , the heating element  40  extends along an outer circumferential surface of the first fixed portion  62 , down along an outer peripheral edge of the first fixed portion, and then inward along an inner circumferential surface of the first fixed portion  62 . In this embodiment, the heating element  40  may be fixed by inserting the end of the heating element  40  facing the elastic conductive part  50  between the first fixed portion  62  and the second fixed portion  64 . When so coupled, a contact area between the heating element  40  and the connector  60 , and in particular, the first fixed portion  62 , may be increased. 
     In alternative embodiments, a groove  163  as shown in  FIG. 7  may be formed at an end of a second fixed portion  164  of a connector  160 , and the elastic conductive part  50  may be inserted into the groove  163 . In this embodiment, the elastic conductive part  50  may first apply voltage to the connector  160 , and the voltage applied to the connector  160  may then be applied to the heating element  40 . 
     As described above, voltage applied by the elastic conductive part  50  may be supplied to the heating element  40  via a connector  160  which is made of an allotrope similar to the heating element  40  in electrical properties, and direct contact between the heating element  40  and the elastic conductive part  50  may be prevented, thus reducing or substantially eliminating the risk of defect generation due to localized overheating between the elastic conductive part  50  and the heating element  40 . 
     Additionally, the more uniform surface contact between the heating element  40  and the connector  160  may provide a widened electrical path, thus reducing resistance and the risk of overheating. 
     Shapes of the first fixed portion and the second fixed portion are not limited to the embodiments as described above. For example, as shown in  FIG. 8 , a second fixed portion  264  may include two annular fixed pieces  264   a  and  264   b . The second fixed portion  264  may be installed within a hollow portion of the heating element  40 , with the outer circumferential surface of the second fixed portion  264  positioned against the inner circumferential surface of the heating element  40 . The heating element  40  may then be installed within an inner circumference of a first fixed portion  262  that has a ring shape, with an outer circumferential surface of the heating element  40  positioned against an inner circumferential surface of the first fixed portion  262 . 
     The inside of the second fixed portion  264  may include an inner hole  263  into which the elastic conductive part  50  may be inserted. Due to its elasticity, the elastic conductive part  50  inserted into the inner hole  263  presses outward against the two annular fixed pieces  264   a  and  264   b  of the second fixed portion  264 , thus firmly fixing the heating element  40  in place between the first and second fixed portions  262  and  264 . 
     A heating device as shown in  FIG. 9  may include a heating element  40  that generates heat through, for example, electrical resistance, an elastic conductive part  50  that supplies electricity to the heating element  40 , and a connector  360  provided between the elastic conductive part  50  and the heating element  40 . The end of the heating element  40  may be inserted into the inside of the connector  360 , and the elastic conductive part  50  may be installed on the outside of the connector  360  so as to press on an outer circumferential surface of the connector  360 . 
     The connector  360  may be formed as two plates  360   a  and  360   b , with the end of the heating element  40  inserted between the two plates  360   a  and  360   b  of the connector  360 . The elastic conductive part  50  may be wound around an outer circumference of the connector  360  so as to elastically press on the connector  360 , thereby exerting a force on the two plates  360   a  and  360   b  and fixing the heating element  40  in place therebetween. 
     The connector  360  may have any shape appropriate to receive and fix the heating element  40  in place and transfer voltage applied thereto by the elastic conductive part  50  to the heating element  40 . The heating element  40  may be made of a carbon material and the connector  360  may be made of a graphite material in order to reduce contact resistance due to contact between the connector  360  and the heating element  40 , as set forth above. 
     In accordance with embodiments as broadly described herein, voltage from the elastic conductive part may be supplied to the heating element via a connector made of an allotrope having similar electrical properties to those of the heating element, and direct contact between the heating element and the elastic conductive part may be reduced or substantially eliminated so as to reduce a risk of defect generation due to localized overheating between the elastic conductive part and the heating element. 
     Additionally, assembly of the connector and the elastic conductive part may be simplified, thus improving productivity. 
     A heating device as embodied and broadly described herein may include a heating element heat-generating by using an electrical resistance, an elastic conductive part applying electricity to the heating element and maintaining the tension of the heating element, and a connector provided between the elastic conductive part and the heating element so that the heating element and the elastic conductive part are not directly contacted, and having the heating element fixed in the one side thereof and the elastic conductive part fixed in the other side thereof to allow the current applied from the elastic conductive part to be flowed to the heating element. 
     The heating element and the connector may be made of allotrope material. 
     The heating element may be made of carbon material, and the connector may be made of graphite material. 
     In certain embodiments, the connector may include a first fixed portion formed in a hollow shape, and a second fixed portion whose one side is inserted into the inner circumference surface of the first fixed portion and the inner circumference surface of other side is coupled to the elastic conductive part, wherein the heating element can be fixed by allowing the end of the heating element to be inserted between the outer circumference surfaces of the first and second fixed portions. 
     In alternative embodiments, the connector may include a first fixed portion formed in a hollow shape, and a second fixed portion whose inside is made of a filled-up member, one side is inserted into the inner circumference surface of the first fixed portion and the outer circumference surface of other side is coupled to elastic conductive part, wherein the heating device is fixed by allowing the end of the heating element to be inserted between the outer circumference surfaces of the first and second fixed portions. 
     The second fixed portion may be formed in a cylindrical shape. 
     In certain embodiments, the heating element may surround the outer circumference surface of the first fixed portion and may be fixed by allowing the end of the heating element to be inserted from the side of the first and second fixed portions facing the elastic conductive part. 
     In certain embodiments, any one of the inner circumference surface of the first fixed portion and the outer circumference of the second fixed portion can be formed to be inclined. 
     The connector may be formed to allow the end of the heating element to be inserted therein, the elastic conductive part to be coupled to the outer circumference thereof, and the heating element to be pressed and fixed by means of the tightening force of the elastic conductive part. 
     A heating device as embodied and broadly described herein may include a heating element heat-generating by using an electrical resistance, an elastic conductive part applying electricity to the heating element and maintaining the tension of the heating element, and a connector provided so that the portion in the heating element to which the electricity is applied, forms surface contact. 
     Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” “certain embodiment,” “alternative embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment as broadly described herein. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments. 
     Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.