Patent Publication Number: US-8973568-B2

Title: Gas oven

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to DE 102010042878.7 filed on Oct. 25, 2010, the contents of which are incorporated by reference for all that it teaches. 
     FIELD OF APPLICATION 
     The disclosure generally relates to a gas oven having an oven muffle and at least one gas burner for the oven muffle. 
     BACKGROUND 
     Gas ovens having an oven muffle which is heated by a gas burner are generally known. However, gas ovens of this kind exhibit a relatively limited level of convenience. 
     SUMMARY 
     The invention is based on the object of providing a gas oven of the kind cited it the introductory part with which problems and limitations of the prior art can be eliminated and the variety of functions of a gas oven can be expanded. 
     In one embodiment, a gas oven having an oven muffle is provided, having an electrical functional unit and having at least one gas burner for said oven muffle, wherein the gas oven has a thermogenerator for generating electrical energy during operation of the at least one gas burner for the purpose of supplying electrical energy to the electrical functional unit, wherein the thermogenerator is designed and arranged to be heated and for heat to be introduced by said gas burner. 
     This object is achieved by a gas oven having the features of as claimed herein. Advantageous and further refinements of the invention are the subject matter of the further claims and will be explained in greater detail in the text which follows. The wording of the claims is incorporated in the content of the description by express reference. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the invention are schematically illustrated in the drawings and will be explained in greater detail in the text which follows. In the drawings: 
         FIG. 1  shows a schematic functional illustration of a gas oven having a gas burner and having a fan in an oven muffle, and also having various mounting options for thermogenerators, and 
         FIG. 2  shows an alternative embodiment of a gas oven having an air duct and a gas burner together with a fan and a thermogenerator. 
     
    
    
     DETAILED DESCRIPTION 
     The concepts disclosed herein provide for a gas oven to have a thermogenerator in order to generate electrical energy during operation of at least one gas burner. To this end, as will be explained in greater detail later, the hot side of the thermogenerator is heated by the gas burner, with the thermogenerator being of appropriate design and being arranged on the gas burner or forming a thermally conductive connection with said gas burner. The thermogenerator can then supply or operate an electrical functional unit with the electrical energy it generates. It is therefore possible, by virtue of the invention, to dispense with a separate electrical connection of the gas oven. This firstly means that a gas oven can be positioned in a kitchen or another area more easily and freely. Primarily, it is also possible, as a result, to use a more convenient gas oven of this kind, for example, in remote areas without a connection to a power supply, it being possible to viably operate said gas oven with gas cylinders instead of with a fixed gas line. 
     In another embodiment, the gas oven has an energy store in which electrical energy which is generated by the thermogenerator can be stored. Rechargeable batteries are suitable for this purpose. As a result, it is primarily possible for electrical energy from the thermogenerator which is not entirely drawn by the electrical functional unit of the gas oven to be stored for times at which the electrical energy which is generated by the thermogenerator possibly may not be sufficient at that time. As an alternative, said electrical energy can be used for functions of the electrical functional unit which are already meant to be available when the gas burner is not yet operating or has been interrupted. This will be explained in greater detail below in respect of the individual functional units. 
     In another embodiment, the electrical functional unit is an electric fan or a blower. Therefore, a convection mode can be realized in the gas oven in accordance with a conventional convection oven. Therefore, an electrically independent gas oven with a convenient convection function can be provided as a result. 
     A further embodiment for an electrical functional unit is an electrical or electronic controller of the gas oven instead of a mechanical control means. These are known for electric ovens and can also be adopted for an electrically independent gas oven of this kind without a great deal of modification. An electronic controller can advantageously have electrical operator control elements, in particular so-called touch-operated switches, and also convenient and extensive indicators, in particular indicator lamps. Furthermore, the electronic controller in the form of an electrical functional unit can serve to carry out intelligent cooking processes with targeted influencing of process parameters, for example for automatically switching off the oven at the end of a cooking period. 
     Further electrical functional units can be in the form of roasting spits with radio transmission for measuring the temperature in a roast or product being cooked, in the form of a lighting means for the oven muffle or the gas oven, advantageously by energy-saving LEDs, or in the form of an ignition module for ignition-module operation of the gas burner or of the gas oven. The convenience and the variety of functions of an electrically independent gas oven can also be improved as a result. 
     In order to introduce thermal energy into the thermogenerator, provision may advantageously be made for a hot side of the thermogenerator to not only generally face the gas burner, but possibly to be directly acted on by said gas burner during operation of the gas burner. The cold side of the thermogenerator can be cooled either in relation to the area surrounding the gas oven, that is to say to the outside, or in relation to the oven muffle or an oven muffle wall. The very large temperature gradient of more than 600° C. of the gas flame in relation to the ambient temperature can advantageously be used when the cold side is cooled in relation to the area surrounding the gas oven. Therefore, the thermogenerator can either generate a very large amount of electrical energy or else be relatively small. The problem with this may be the subsequent heating of the area surrounding the gas oven and possibly undesired heating in critical regions. Furthermore, the energy which is diverted away by the thermogenerator is lost to the cooking process or the oven muffle. 
     Furthermore, it is considered to be advantageous to cool the cold side of the thermogenerator in relation to the oven muffle or an oven muffle wall. Since the temperatures which are usually generated in an oven are in the region of around 200° C., it can be assumed that the temperatures in the oven muffle and at the oven muffle walls are not higher than 250° C. Therefore, a temperature gradient of at least 350° C. is available, and this should be large enough to generate the required electrical energy. Furthermore, the energy which is conducted by the thermogenerator is not lost to the heating process either; the gas oven therefore operates in a more energy-efficient manner overall and negative effects on the area surrounding the gas oven can also be avoided. 
     In a yet further embodiment, the thermogenerator can also be heated by the gas burner, however it cannot be acted on directly by the gas flames. An air duct can be provided in which an air stream for a convection mode of the gas oven is routed. The cold side of the thermogenerator can be acted on by the air stream arriving from the oven muffle and can therefore be, as it were, cooled. Immediately thereafter, the air stream is conducted past the gas burner in a substantially customary manner in order to be heated. The hot side of the thermogenerator is also provided here, advantageously in the form of a wall of a duct for conducting the air stream, and therefore the gas burner also heats the hot side of the thermogenerator, as is desired. Provision may also be made for the thermogenerator to be arranged in an air flow path, as it were, in such a way that its cold side is cooled by said air flow path and its hot side is heated by said air flow path at the same time. The thermal energy which is output on the cold side is then likewise specifically drawn away or, as it were, captured and is not lost to the heating process. 
     In a yet further embodiment, provision can be made for the gas burner and the thermogenerator to be designed such that the gas burner itself generates, at its minimum power level, precisely that thermal power which, during operation of the gas oven, ensures that the thermogenerator generates enough electrical power to operate the electrical functional unit. This is also advantageous for the described operation with a fan which is supplied with power by the thermogenerator since said fan is also only required when the gas burner is operating. In this case, the gas oven can operate with the fan in the convection mode from the very beginning. As an alternative, provision may be made for the gas oven to first be heated for a period of time and for the thermogenerator to not yet generate enough electrical energy to operate the fan. The fan can start up for the purpose of a convection mode only when this is achieved. 
     These and further features can be gathered not only from the claims but also from the description and the drawings, where the individual features can be realized in each case by themselves or in combination in the form of subcombinations in an embodiment of the invention and in other fields and can constitute advantageous and inherently patentable embodiments for which protection is claimed here. The subdivision of the application into individual sections and subheadings do not restrict the general validity of the statements made thereunder. 
     Turning now to the figures,  FIG. 1  illustrates a gas oven  11  according to a first embodiment which has a housing  12  and an oven muffle  13  in said housing. The lower region of the oven muffle  13  contains a gas burner  15  having a gas feed line  16  into which a gas valve  17  is looped in order to control the gas supply. In this case, the gas burner  15  can be designed such that no open gas flames can enter the main area of the oven muffle  13 . However, this is known to a person skilled in the art in principle and can be implemented by cover plates or the like, and under certain circumstances a kind of intermediate floor is once again provided in the oven muffle  13  above the gas burner  15 . In respect of the components described up to this point, the gas oven  11  corresponds to a conventional gas oven and conventional components can advantageously be used. 
     A fan  19  is schematically illustrated at the top-right of the oven muffle  13 , said fan having the function of a conventional fan for a convection oven or fan oven. The fan  19  can draw air by suction from the oven muffle  13  and blow it back again in the manner which is known in principle to a person skilled in the art. However, this will still be explained in greater detail below. 
     According to one embodiment, a first thermogenerator  21   a  is arranged at the top of the gas burner  15 , with said thermogenerator covering only a relatively small portion of the surface of said gas burner. The thermogenerator  21   a  is in the form of a conventional thermogenerator and has a substantially disk-like shape. In this case, said thermogenerator is arranged such that it bears against the gas burner by way of the hot side which is conventional for thermogenerators and is heated by said gas burner so that heat is introduced into the thermogenerator  21   a.  The cold side of said thermogenerator faces the oven muffle  13 . 
     In addition or as an alternative, a second thermogenerator  21   b  can be provided, specifically at the bottom-left of the side wall of the oven muffle  13 . The hot side of the thermogenerator  21   a  projects just above the gas burner  15  into the oven muffle  13  or against the gas burner  15 . The other side of said thermogenerator is, as the cold side, connected to a thermal conduction component  23  which is routed to an outer wall of the housing  12  and, under certain circumstances, can also be provided with a fan, a heat sink or the like. 
     In respect of the functioning of the thermogenerator  21   a,  it should be stated that it is acted on by the gas burner  15  with a temperature of over 600° C. on its hot side which faces downward. The maximum temperature which usually prevails in the oven muffle  13  is 200° C. to 300° C., and therefore a temperature gradient of at least 350K is available to the thermogenerator  21   a  for thermal heat transfer. Therefore, enough electrical energy to operate the fan  19  can be generated by corresponding, skilled selection of the materials and the design of the thermogenerator  21   a . To this end, the thermogenerator  21   a  is connected to a controller  25 , such as a microprocess, which has an energy store  26 , for example a rechargeable battery. The controller  25  can therefore drive the fan  19  with the electrical energy from the thermogenerator  21   a . If operation of said fan is desired at the beginning of the process of heating the oven muffle  13 , but the thermogenerator  21   a  is not yet delivering enough electrical power, the controller  25  can draw this electrical power from the energy store  26 . 
     In respect of the functioning of the second thermogenerator  21   b , it should be stated that, depending on how close it is arranged to the gas burner  15 , it is acted on partly by the oven temperature of said 200° C. to 300° C. and partly also by the gas burner  15  by way of its hot side which faces to the right. The cold side of said thermogenerator is coupled to the wall of the housing  12  or to the ambient temperature, for example to a heat sink, by the thermal conduction component  23  which conducts heat very well. Therefore, a temperature of usually approximately 20° C. to 30° C. prevails here. This produces a temperature gradient of approximately 200K for the thermogenerator  21   b , this in turn being sufficient to generate enough electrical power or energy to operate the fan  19 . This fan does not have to exhibit a particularly high power, as is known in such fans for convection ovens. However, the second thermogenerator  21   b  has the disadvantages that the surrounding area is unnecessarily or undesirably heated and that energy is drawn from the heating process in the oven muffle  13 . It is therefore considered to be advantageous to provide only the thermogenerator  21   a  on the gas burner  15 . 
     The controller  25  is further connected to two operator control elements  28  on the gas oven  11  and to an indicator lamp  29 . The operator control elements  28  can be, for example, electronically actuated and evaluated touch-operated switches with which the gas valve  17  for the gas burner  15  is controlled by means of the controller  25 , which is permanently supplied with electrical energy by the energy store  26 . As an alternative, convenience functions, such as timer functions or the like, can be realized. Therefore, the operator control elements  28  are also one of the options cited in the introductory part for the electrical functional unit of the gas oven which is operated by a thermogenerator. This is also true of the indicator lamp  29  which can be realized, for example, in an energy-saving manner by LEDs. 
     In the alternative exemplary embodiment of a gas oven  111  according to  FIG. 2 , a gas burner  115  is not arranged directly in an oven muffle  113  but outside it. An air duct  114  is routed out of the oven muffle  113  and back into said oven muffle in a U-shaped loop. An air stream, which is illustrated using arrows, is generated by a fan  119  at the top-left end of the air duct  114 . The gas burner  115  is arranged beneath the lower branch of the air duct  114  and heats up the air flowing through in a conventional manner, said air then being returned to the oven muffle  113 . Since cooler air is drawn by suction from the oven muffle  113  in the upper region of the air duct  114  and this air is then returned with a considerably higher temperature after being heated by means of the gas burner  115 , it is possible to arrange a thermogenerator  121  between said oven muffle and gas burner. The hot side, which faces downward, of said thermogenerator is heated by or draws heat from the gas burner  115  or the hot air stream in the lower air duct  114 . The thermogenerator  121  passes this heat to its upwardly facing cold side in the upper air duct  114  or to its relatively cold air. In particular, the cold side of the thermogenerator  121  is therefore cooled by the fan  119  in this way. A significant temperature gradient can also be generated at the thermogenerator  121 , said thermogenerator then generating electrical energy again, this electrical energy being passed to a controller  125  together with an energy store  126  in accordance with  FIG. 1 . 
     The fan  119  is also controlled by the controller  125  and supplied with electrical energy by the thermogenerator  121 . The energy store  126  serves as an intermediate storage means or an energy buffer store if the controller  125  is also required to operate without operation of the thermogenerator  121  or if the fan  119  is intended to already be in operation even though the gas burner  115  is not yet generating enough electrical energy at the thermogenerator  121 . 
     Therefore, the exemplary embodiments according to  FIGS. 1 and 2  can provide electrically independent gas ovens which can provide, without electrical connection, convenience functions for electrical functional units which are normally possible only with power being supplied. Further examples (which are not illustrated here, however) of electrical functional units are a so-called roasting spit with radio transmission and an ignition module for the gas burner, as have been cited in the introductory part. It is readily possible to imagine how they could be provided in addition to the exemplary embodiments described here.