Abstract:
With a method for controlling a gas burner, the latter is supplied with gas by an electronically controllable gas valve, wherein it is supplied with gas by the gas valve in a low power range and in a high power range. Only one of the power ranges is available at any point in time, wherein in each of the power ranges a power from a minimum power to a maximum power can be preset at the gas burner using an operating element. The low power range and the high power range differ here by more than 50%.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of German patent DE 10 2010 023 090.1, filed on May 31, 2010, the contents of which are incorporated by reference for all that it teaches. 
       BACKGROUND 
       [0002]    The invention relates to a method for controlling a gas burner and a hob with several gas burners, using which, or on which, the method is performed. 
         [0003]    It is known from DE 10 2010 005 655.3, dated Jan. 19, 2010 how to set a flame circle of said gas burner depending on a diameter of a cooking pot placed on a gas burner, which flame then corresponds to a certain determined power level. This allows a gas burner to operate in an energy-optimized range. 
         [0004]    An object underlying the invention is to provide a method as stated at the outset and also a corresponding gas hob for performing said method, where problems arising from the prior art can be eliminated, and in particular, versatile and advantageous operation of a gas burner is possible. 
       SUMMARY 
       [0005]    This problem is solved by a method having the features as claimed herein. Advantageous and preferred embodiments of the invention form the subject matter of the further claims and are explained in greater detail in the following. Some of the features stated in the following are described only for the method or only for the gas hob. Regardless of this, they should however be applicable both for the method and for the gas hob. The wording of the claims is made into part of the substance of the description by express reference. 
         [0006]    A gas burner is supplied with gas by an electronically controllable gas valve, which is in particular steplessly controllable. In one embodiment, the gas hob advantageously has only electronically controllable gas valves for controlling the gas burners, where shut-off valves of conventional design are provided for mandatory for safety reasons. These valves can however only be completely shut or completely opened. “Stepless” in the context of the present application should be able to mean both stepless and with fine subdivision into many small steps. 
         [0007]    In accordance with one embodiment of the invention, there is a low power range and a high power range for the gas burner or its gas valve. In both power ranges, the gas burner is supplied with gas by a gas valve or operated advantageously steplessly or without steps, for which purpose it is the gas valve being operated accordingly. Only one of the power ranges is available at any point in time, meaning that the gas burner with its gas valve is either in one power range or the other. Actuation of a special operating element permits switching between the power ranges. While the gas burner with its gas valve is in one of the power ranges, any change to the power setting only effects a change in this particular power range. With one operating element, it is possible to set, in each of the power ranges, a power at the gas burner, which ranges from a minimum power to a maximum power, said power corresponding to a setting or position of the operating element. 
         [0008]    In the low power range, setting a minimum power with the operating element sets the gas burner at the minimum power necessary for steady operation of the gas burner. Below this power, the flame would not burn reliably or steadily enough, or could even go out. This is predetermined by the design and can be influenced in such a way that this value can be adjusted upwards or downwards as a limit value. With a maximum power setting of the operating element, a maximum power is obtained at the gas burner and at the gas valve and is, in turn, considerably below a highest operating power of the gas burner. This highest operating power of the gas burner is predetermined by the design and should not, or cannot, be exceeded. 
         [0009]    In the case of the high power range, it is provided that after setting a minimum power at the operating element, a minimum power is set at the gas burner which is considerably above the previously stated lowest operating power of the gas burner. With a maximum power setting of the operating element, a maximum power is set at the gas burner and at its gas valve which is close or equal to the previously stated highest operating power of the gas burner. The gas burner design would not permit continuous operation with much greater power, which is, for example, due to a maximum flow cross-section at the gas burner. 
         [0010]    For the low power range and the high power range, it remains the case that each medium power setting of the operating element as the medium power in the respective power range is considerably different and the medium power of the low power range is considerably below that of the high power range. 
         [0011]    It is therefore possible with the invention for a gas burner together with its gas valve to be set in at least two power ranges and be adjustable within these from the lowest to the highest power setting in each case. Here the gas burner practically corresponds in the low power range to a smaller gas burner and in the high power range to a larger gas burner. Advantageously, the power ranges can differ by at least 30% to 50%. This can be such that they differ in their minimum power by at least 50% and in their maximum power by at least 30%, preferably also by at least 50%. The change between the two power ranges is made only by another operation or setting of the gas valve using the operating element or using a control unit associated with the operating element for the gas burner or for the entire gas hob. 
         [0012]    With the invention, it is possible for a single gas burner to cover the power range of at least two gas burners of differing power. It is, for example, possible in a hob with four gas burners to simulate the power range of typical gas hobs having five gas rings or five gas burners. This is because the advantage of gas hobs with five gas burners is that a gas burner adapted as well as possible to each pot size is available. Only in very rare cases are all five gas rings or gas burners used for cooking at the same time. It is not possible with a gas hob having, for example, four gas burners to increase the total number of gas burners, as they of course remain four in number. An operator does however have a variance with regard to power from at least five gas burners, meaning he can use such an adjustable gas burner, adapted to a required pot size, for a small pot with a characteristic as for a small gas burner, and for a large pot with a characteristic as for a large gas burner. It goes without saying that a gas burner cannot be operated at any power, as this is determined by the gas outlet openings and the like in accordance with the design. Nevertheless, the aforementioned variance in the power of approximately 50% can be readily achieved, corresponding to approximately the difference between a small gas burner and a medium-sized one. 
         [0013]    With the aforementioned medium power of the two power ranges, corresponding to a medium power setting at the operating element, there can be a power difference likewise of at least 30%. Advantageously the power difference here too is approximately or at least 50%. 
         [0014]    The power ranges in form of the low power range and the high power range and the power setting can preferably be adjustable exclusively via a single gas valve per gas burner. This should exclude a bypass mechanism or a throttle or the like. 
         [0015]    In a further embodiment, at one point of time, only one of the power ranges is available. This means that the gas burner with its gas valve is available or operating either in one power setting or in the other power setting. 
         [0016]    In a further embodiment of the invention, the power ranges should be able to change between the minimum power and the maximum power to some extent continuously or in linear form, for example as is possible in conventional gas burners together with gas valves, in particular when the gas valves are electronically controlled. 
         [0017]    A low power range can extend from about 200 W to about 2000 W. The 200 W setting is then advantageously about the lowest operating power of the gas burner for its continuous operation, which is thus determined by the design or can be influenced by other factors, but which could also be different given another design. It cannot be operated in continuous mode with less power, as otherwise the flame is not stable. If a lower power is required, the gas burner would have to be operated in pulses. 
         [0018]    The power can advantageously extend, in the high power range, from about 500 W to about 3500 W. The highest operating power of the gas burner for continuous operation is about 3500 W. More gas cannot, for example, flow out of the gas burner at all due to its design or due to a built-in throttle valve inside it, even if the associated gas valve is fully opened. The value can also be different or higher due to a different design. 
         [0019]    In a further embodiment of the invention, it is possible for the size of a pot placed on the gas burner to be automatically recognized. This recognized size is then compared with a predetermined limit size of the pot, which is defined for this gas burner. Pot size recognition systems of this type are also known for gas burners. An automatic switchover between the two power ranges then takes place, such that with a smaller pot below the limit size of the pot the low power range is selected for operating the gas burner. In the case of a larger pot above the limit size of the pot, the high power range is selected. It is therefore not necessary for an operator make the adjustment of the power range of this gas burner to the pot size, instead the system does this automatically. This prevents the adjustment being forgotten by an operator. Furthermore, an automatic recognition feature can operate optimally and thus possibly also save energy. A control unit can of course provide that an operator can also switch off an automatic mode of this type. 
         [0020]    In further embodiment of the invention, a joint operation of two adjacently arranged gas burners is possible with the method in accordance with the invention. It can be provided here that in the case of the gas burners which designed with a slightly different size for slightly different power ranges, changing of the power range adjusts at least one of the two gas burners to the predetermined or set power range of the other gas burner. This is achieved in that the two gas burners then have identical power ranges in the sense that the minimum power and the maximum power are each identical within the power ranges. As a result, two adjacently arranged gas burners can be synchronized with respect to the power they generate. To do so, the gas valves operating the two gas burners are set in this way in respect of the power range. A control unit then operates the two gas valves in the same way or with the same power setting, which is not a problem since when the power ranges are identical, identical power settings also generate the same power at the respective gas burner. It is then possible that a large roasting pan, for example, or the like is evenly heated with two gas burners over which it is placed. 
         [0021]    Furthermore, operation by the person can be very greatly simplified when, for example, he sets a required power at only one operating element of one of the two gas burners and when both gas burners are operated with the same power thanks to the adjustment of the power ranges. The other operating element of the other gas burner is then either deactivated or automatically adjusted by the control unit, for example, to indicate to an operator that both gas burners are in use. This is particularly effective with operating elements in the form of touch switches with display elements in the form of seven-segment displays or the like. 
         [0022]    In yet another embodiment of the invention, an adjustment of the power ranges of the gas burner can be used to compensate for different types or grades of the supplied gas. This is because gases have different calorific values. In Germany, for example, the calorific value of the supplied gas can fluctuate by up to 15%. To ensure that this does not show at the power setting of a gas burner, i.e., that it is not suddenly 15% lower or higher, it is possible by means of a gas sensor to recognize the type or quality of the supplied gas. This information is passed to a control unit of the gas hob, which then adjusts accordingly the power range of the gas burner or of its gas valve. This means that when the gas quality is poor, a power range closer to the high power range is set. When the gas quality is good, a power range closer to the low power range is set. In this way it is possible, for example, after moving into a house and when lower-quality gas is supplied, for the power setting 5 or also the maximum power setting to achieve the same result at a gas burner as with the previous connection to a higher gas quality. 
         [0023]    With a gas hob in accordance with the invention, at least one gas burner advantageously has an electronic gas valve. A control unit is provided that can operate the gas valve in accordance with the method as mentioned. Advantageously, all gas burners have an electronic gas valve of this type. The gas burners can differ in their design with regard to their power ranges, so that at least one gas burner is designed smaller for a lower power range and at least one gas burner is designed larger for a higher power range. By means of the aforementioned alignment, these two gas burners can be adjusted relative to one another for joint operation, or it is possible by means of adjustment of the power range to offer more gas burners than are actually provided. 
         [0024]    Preferably, the electronic gas valve is controllable or adjustable continuously without steps and can be the only gas valve for the gas burner. Furthermore, the electronic gas valve can be the only continuously controllable gas valve. 
         [0025]    These and further features can be gathered not only from the claims, but also from the description and drawings, where the individual features, both singly or severally in the form of subcombinations, can be implemented in embodiments of the invention and in other fields and can represent advantageous and independently protectable designs for which protection is claimed here. The subdivision of the application into individual sections and subheadings in no way restricts the general validity of the statements made thereunder. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    Embodiments of the invention are shown schematically in the drawings and are explained in detail in the following, wherein: 
           [0027]      FIG. 1  discloses a schematic illustration of the function of a gas hob having three conventional gas burners and one gas burner in accordance with one embodiment of the invention and 
           [0028]      FIG. 2  discloses a diagram showing the generated power P at the gas burner over the power setting L with a low power range and a high power range. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]      FIG. 1  shows a gas hob  11  in a schematic plan view in accordance with one embodiment of the invention. The gas hob  11  has four gas burners  12   a  to  12   d,  in a manner known per se. Here the front left gas burner  12   a  is a relatively small gas burner, for example for a power range of 150 W to 1200 W. The rear left gas burner  12   b  is a medium-sized gas burner intended and designed for a power range of 200 W to 2000 W. The rear right gas burner  12   c  is a relatively large gas burner designed for a power range of, for example, 500 W to 3500 W. The front right gas burner  12   d  is a further medium-sized gas burner that, however, is designed in accordance with an embodiment of the invention and can also operate in accordance with the invention. It can operate firstly in a low power range, which as for the gas burner  12   b  extends from 200 W to 2000 W, with 200 W being the lowest emitted continuous power or the lowest operating power, and with 2000 W being the highest power in the maximum setting of an operating element, or the maximum power. Purely from design principles or the size, in particular the diameter of the burner, the gas burner  12   d  corresponds to the gas burner  12   b.  For that reason, its low power range also matches the power range of the non-variable gas burner  12   b  in this design. 
         [0030]    Furthermore, the gas burner  12   d  can, as described in further detail in the following, be operated in a high power range. Here the aforementioned minimum power is 500 W and the maximum power 3500 W, corresponding to its highest operating power. It therefore corresponds here to the rear right gas burner  12   c  of considerably larger design. 
         [0031]    Gas is supplied to the gas burners  12   a  to  12   d  via a main gas line  14  into the gas hob  11 . A gas valve  15   c  for the rear right gas burner  12   c  and a gas valve  15   d  for the front right gas burner  12   d  branch off from the main line in the example. The gas valve  15   c  is settable with an operating element  17   c  and the gas valve  15   d  with an operating element  17   d.  The same applies for the operating elements  17   a  and  17   b  for the gas burners  12   a  and  12   b  respectively. The operating elements  17  are, like the gas valves  15   a  to  15   d,  connected to a control unit  16  of the gas hob  11  via connecting lines, not shown. Furthermore, an additional operating element  19  is provided for the gas burner  12   d  or its operating element  17   d.  Using this additional operating element  19 , the gas burner  12   d  can be switched between the low power range and the high power range. It can in principle be of any design, for example a pushbutton, rotary knob or touch switch. 
         [0032]    In the low power range, the gas valve  15   d  controls the gas burner  12   d  or supplies it with a certain quantity of gas in accordance with commands that it receives from the operating element  17   d  via the control unit  16 . If the operating elements  17   a  to  17   d  are simple toggle switches, as is frequently the case for gas hobs, the rotation distance of usually about 300° is subdivided into nine power settings as plotted in the diagram in  FIG. 2  on the axis towards the right. Either a precisely determined power determined by a certain gas quantity passing through the gas valve  15   d  to the gas burner  12   d  can be assigned to each whole-numbered power setting, or settings for finer graduations can be provided between the whole-numbered power settings and then result in an approximately intermediate power at the gas burner  15   d.    
         [0033]    Alternatively, a continuous power curve can be provided, as illustrated in  FIG. 2 , or the graduation can be so fine that the power curve is practically continuous and steadily increasing. Thus signals or operating commands are generated at the operating element  17   d  depending on its setting and are then assigned by the control unit  16  either to a low power range shown as an unbroken line  200  or to a high power range shown as a dashed line  250 , depending on the status of the additional operating element  19 . Depending on this, the control unit  16  in turn operates the gas valve  15   d  in such a way that the power curves from  FIG. 2  are obtained either in the low power range or the high power range. It can thus be seen that in the setting 1  280 , i.e. the lowest power for continuous operation of the gas burner  12   d,  the power point  290  in the low power range is 200 W, i.e., the lowest operating power, and in the high power range the power point  295  is 500 W. With the setting 5 as the medium power setting, the power point  275  in the low power range is about 700 W and in the high power range the power point  265  is about 1500 W. At the highest setting, setting 9, the power point  225  in the low power range is the aforementioned 2000 W and in the high power range the power point  230  is 3500 W, i.e., its highest operating power. 
         [0034]    It is thus possible, by actuating the additional operating element  19 , to switch freely back and forth between the low power range and the high power range of the gas burner  12   d.  Alternatively, it can be provided that the low power range for which the gas burner  12   d  is actually designed in terms of its size is made the standard setting. With normal actuation of the operating element  17   d,  therefore, the low power range is covered and the gas valve  15   d  supplies the gas burner  12   d  with a corresponding amount of gas. It is only by the additionally possible actuation of the additional operating elements  19  that the gas burner  12   d  can be switched to the high power range and then operated by appropriate settings at the operating element  17   d . It can be provided here that the gas burner  12   d,  when switched off using the gas valve  15   d  and the control unit  16 , switches back to the low power range and when next switched on is back in the low power range. 
         [0035]    It can thus be seen that the change in operation of the gas burner  12   d  on the one hand in the low power range and on the other hand in the high range practically provides five gas rings on the gas hob  11 , i.e., at the gas burner  12   a  with low power, at the gas burners  12   b  and  12   d  with medium power and at the gas burners  12   c  and  12   d  with high power. There are thus five different power ranges available, although of course only four gas burners  12   a  to  12   d  are provided. 
         [0036]    A further possibility in accordance with the invention is that the gas burner  12   d  can be operated by means of the additional operating element  18  together with the gas burner  12   c.  To do so, after actuation of the additional operating element  18 , or if necessary also after actuation of the further additional operating element  19 , the gas burner  12   d  can be operated by means of its gas valve  15   d  in the high power range, corresponding to that of the gas burner  12   c.  Furthermore, the control unit  16  then operates the two gas valves  15   c  and  15   d  equally, i.e., in each case with the same power setting, so that the two gas burners  12   c  and  12   d  generate the same power. This can be used to place an elongated and large roasting pan on the two gas burners  12   c  and  12   d  or their gas rings. The required power setting can then be set by this combination at the control unit  16  using one of the operating elements  17   c  or  17   d,  or it can be provided that for a combined operation of this type one of the operating elements  17   c  or  17   d  is solely responsible. This can be, for example, the operating element  17   c  of the larger gas burner  12   c.  Commands entered for the operating element  17   d  can then be ignored and have no effect. 
         [0037]    An actuation of the operating element  17   c  then operates via the control unit  16  the gas valves  15   c  and  15   d  each with the same power setting, so that a roasting pan placed on the two gas burners  12   c  and  12   d  is evenly heated by them. The combined operation can be stopped again either by resetting the power to zero at the operating element  17   c  or by again actuating the additional operating element  18 . This has the advantage that when only one of the gas burners  12   c  or  12   d  is switched on again using the corresponding operating element  17   c  or  17   d,  they do not suddenly both come into operation, when one of them is not required. 
         [0038]    In yet another embodiment of the invention, it is possible by means of a gas sensor  20  provided on the main gas line  14  to recognize the supplied gas type or at least its calorific value. From this it is then possible, as explained at the outset, for the various gas burners  12   a  to  12   d  to be adjusted using their gas valves  15   a  to  15   d  such that for example the gas burner  12   d  always supplies 2000 W of combustion power at the maximum power setting  9  in the low power range, regardless of the calorific value of the supplied gas. For gas of poor quality, the gas valve must be opened slightly further than otherwise to do so, and for gas of particularly good quality slightly less. This is, however, no problem for the control unit  16 . 
         [0039]    In another readily conceivable embodiment of the invention, a further sensor can be provided, for example in accordance with DE 10 2009 024 236 A. This sensor can recognize in the manner explained at the outset the size of a pot placed on it and adjust the power range at the gas burner accordingly by setting a low power range or a high power range or also an intermediate medium power range.