Automatic boiling program for a cooking system

Abstract

The present invention relates to a method of heating a liquid to boiling from a pre- boiling phase, comprising the steps of: Providing a cooking system comprising a cooking hob and a cookware containing said liquid. The cookware comprising a base part for placing on said cooking hob, a temperature sensor, a power supply and a transmitter. Selecting, by a user, a boiling program among a plurality of cooking programs. Applying power to the cookware using the cooking hob to raise a temperature of the cookware wherein the power includes a heat-up power which is automatically applied to the cookware in the pre-boil phase on the basis of the user- selected boiling program, and subsequently automatically reducing the applied power to a maintain power determined by the user-selected boiling program.

Description

AUTOMATIC BOILING PROGRAM FOR A COOKING SYSTEMField of the invention

[0001] The present invention relates to a method for automatic boiling of a liquid contained in a cookware and system for implementing such method.Background of the invention

[0002] When heating / boiling a liquid contained in a cookware placed on an induction hob, the liquid closest to the bottom of the cookware may have a higher temperature than the liquid closest to the top of the cookware. This difference in liquid temperature may be higher when the liquid is water and there is salt in the water in that the salt concentration at the bottom of the cookware may be higher than towards the top. This leads to a difference in temperature of the liquid in the cookware. Such differences may be minimized by stirring of the liquid.

[0003] In the art documents exists that describe stirring of a liquid by heating the liquid to its boiling temperature. One such document is JP5083418 which discloses a heating coil driven by converted high-frequency power which arouses convection inside a pan and stirring cooking materials by convection. Another example is FR3108821 which disclose a program that brings a liquid to a temperature where it is boiling and subsequently maintain the liquid at its boiling temperature by controlling power to the induction coils over which the cookware is positioned. The temperature response is provided by as stand-alone temperature sensor positioned inside the liquid to be heated.

[0004] A problem arises when boiling a liquid, and in particular water comprising salt. Saltwater has a higher density than regular (non-salted) water. Actually, hot (more than 100 degrees Celsius) salt water with high salt concentrations is heavier than cold unsalted water. This has the effect that convection is first effectful when the salt water is boiling (converting / transitioning into gaseous form). Detecting this transition is difficult in practice, and in many situations this results in boiling over of the liquid.Summary of the invention

[0005] The inventors have identified the above-mentioned prior art and the problems and challenges related to cooking different types of food items requiring different cooking / heating profiles, different boiling temperature etc. for optimal cooking and subsequently made the below-described invention which can be used to automatically cook a variety of different food items.

[0006] An aspect of the invention relates to a method of heating a liquid to boiling from a pre-boiling phase, comprising the steps of- providing a cooking system comprising a cooking hob and a cookware containing said liquid, said cookware comprising at least a base part for placing on said cooking hob, one or more temperature sensors, a power supply and a transmitter,- selecting, by a user, a boiling program among a plurality of cooking programs of said cooking system,- applying power to said cookware using said cooking hob to raise a temperature of said cookware; wherein said applied power includes a heat-up power which is automatically applied to said cookware in said pre-boil phase on the basis of said user-selected boiling program, and- subsequently automatically reducing said applied power to a maintenance power determined by said user-selected boiling program.

[0007] Thereby is provided an advantageous method of heating a liquid to boiling from a pre-boiling phase such that sufficient power is supplied to the cookware to ensure homogeneous heating of a liquid contained therein.

[0008] An example of a liquid is water which is in its liquid state when a user starts a boiling program. As the water is heated small bubbles may start rising to the top surface of water in the cookware. These initial bubbles may be attributed to thepresence of carbon dioxide in the water, which evaporates when the liquid is at about 80 degrees Celsius, as well as precipitation of lime. As the water is heated above a certain boiling temperature it starts changing state to its gaseous state. This transformation is visible in a cookware containing the water as larger bubbles rising towards the top surface of the water in the cookware. Other types of liquid may also be brought to boiling by the method of the present invention such as milk, sauces, stocks, and simmer dishes.

[0009] It should be noted that the cookware in addition to containing the liquid also may contain food items such as vegetables such as potatoes, carrots, broccoli, or other types of food items such as rice, corn, and eggs. Especially, it should also be noted that in addition to containing liquid, the cookware may also comprise salt. The significance of salt will be discussed in greater detail below. Hence, such food items are prepared according to the selected cooking program.

[0010] In the context of the present invention, the term “pre-boiling phase” is understood as a phase of the liquid at which bubble formation has not yet occurred. In other words, the pre-boiling phase designates a state of a liquid that has not yet reached a high enough temperature to be boiling. This also implies that the term “boiling” refers to any boiling intensity at which bubble formation occurs.

[0011] Maintaining water as an example, knowing that the invention can be applied to other types of liquid, one definition of boiling may be when gaseous water moves towards the top surface of the water column contained by the cookware.

[0012] Boiling is the physical process of converting a liquid such as water from a liquid state to a gaseous state. For pure water (without e.g., salt) at standard pressure of 1013 Hectopascals (standard sea level pressure) the temperature at which boiling occurs is 100 degrees Celsius. In this document, this temperature is referred to as the scientific boiling temperature of water. In the same way, other liquids also have a scientific boiling temperature.

[0013] Said in another way, the scientific boiling temperature (or scientific boiling point) of a liquid is the temperature at which vapor pressure is equal to the pressure ofthe gas above it. However, as air pressure changes with altitude so does the scientific boiling point, and the skilled reader will appreciate that a reference to a boiling temperature or a boiling point is not necessarily a reference to a specific temperature unless a corresponding air pressure is also indicated.

[0014] The boiling of a liquid, such as water, is a gradual process as formation of bubbles of water vapor (water in its gaseous state) occurs well before the boiling point, and the process becomes more vigorous as the temperature of the water reaches the boiling temperature. Increasing the heat applied to the liquid once the boiling temperature is reached will, in general, not lead to an increase in the temperature of the liquid, however, the rate of conversion from liquid phase to gas phase increases, i.e., the boiling intensity increases. Hence, water and liquids in general may boil at different intensities depending on the temperature of the water / liquid and the power applied thereto in the form of heat.

[0015] It should be noted, that if ingredients or food items are included in the liquid the boiling temperature of the mixture may deviate from the scientific boiling temperature. If for example salt is added in the water, the boiling temperature and power needed to reach a desired state of boiling may change.

[0016] The process of boiling a liquid can be divided into a number of temperaturedependent phases leading up to the boiling temperature of the liquid. The boiling programs may each be defined by a temperature at which the liquid is maintained. The temperatures of the boiling programs may be defined by a visual inspection of the liquid as it heats up. One such visual inspection may include determining the number of bubbles that are generated in the water column per time period. When the desired number of bubbles has been reached, the temperature measurement from the temperature sensor is read and used as the target temperature of a particular boiling program. The power used to maintain this target temperature may be referred to as the steady state power, maintenance power, or target power.

[0017] As previously explained, once the boiling temperature of the liquid is reached, increasing the power supplied to the cookware, will not necessarily increase thetemperature of the liquid in a noticeable way, however, an increase in applied power will increase the boiling intensity. Therefore, the process of boiling a liquid may also include substantially temperature-independent phases of different rates of conversion from liquid form to gas form. The boiling programs may also include programs in which the liquid is maintained at the boiling temperature but where the supplied power differs among the boiling programs in such a way that various intensities of boiling are realized. Thus, a boiling program may furthermore be defined by the boiling intensity of the liquid, and therefore in addition to being defined by a liquid temperature, the boiling program may also be defined by power applied to the cookware. Thus, the power referred to as steady state power, maintenance power, or target power, may also designate a power at which a specific boiling intensity is realized.

[0018] The power needed to maintain a target temperature and boiling intensity, i.e., the maintenance power, of the liquid may change in dependency of size of the cookware and volume of liquid therein.

[0019] In an embodiment of the invention, said cookware is an induction cookware and wherein said cooking hob is an induction cooking hob.

[0020] This is advantageous in that it has the effect, that heat can be regulated very fast compared to other types of cooking hobs, such as ceramic cooking hobs.

[0021] In an embodiment of the invention, said cooking system comprises a user interface, wherein said user interface is comprised by at least one item from the list comprising: external electronic device, cooking hob and cookware.

[0022] The cooking system may be controllable from a user interface allowing a user to activate, control, change and monitor the food preparation process. The user interface may be implemented in the cooking hob, in the cookware, or in an external electronic device such as an electronic tablet, a smartphone, a smartwatch, a laptop, or any other computer processing device, for example any other handheld computer processing device. Arranging the user interface in an external device is advantageous in that it has the effect, that more possibilities for adjustment of the food preparationprocess may be achieved, and also improved flexibility of control of the food preparation process may be achieved. The user interface may be a graphical user interface facilitated by an electronic display.

[0023] In an embodiment of the invention, said cooking system comprises a controller for controlling said cooking system.

[0024] The controller may be an external control device for control of said cooking system, the external device comprising or communicating with the user interface. The external control device may be a dedicated control device or be facilitated by a handheld electronic device such as a smartphone, a tablet, a laptop, a smartwatch or any other suitable computing device.

[0025] In an embodiment of the invention, said plurality of cooking programs comprises a plurality of boiling programs, and wherein said step of selecting a boiling program among a plurality of cooking programs comprises selecting a boiling program among said plurality of boiling programs.

[0026] The plurality of cooking programs may comprise a plurality of boiling programs. For example, all cooking programs of the plurality of cooking programs may be boiling programs, or alternatively, the plurality of cooking programs may comprise a plurality of boiling programs and one or more other cooking programs that are not boiling programs, for example cooking programs that automatically execute cooking recipes such as simmering recipes.

[0027] In an embodiment of the invention, said step of selecting a boiling program among a plurality of cooking programs comprises selecting said boiling program using said user interface.

[0028] The user interface may facilitate the user in selecting the desired boiling program among the plurality of cooking programs. The user interface may present the user with a selection of boiling programs that are executable using the cooking system. As an example, the user interface may be a graphical user interface displaying the possible selections to the user, for example using an electronic display such as a touchscreen of an external electronic device. Accordingly, the user may interact with the user interface to select the desired boiling program. Thereby is provided an advantageous way of selecting a boiling program which is both user friendly and which is also convenient as parameters of the cooking programs may also be presented to the user via the user interface thereby assisting the user in selecting the appropriate boiling program.

[0029] In an embodiment of the invention, said selected boiling program comprises one or more input parameters relating to boiling of said liquid, and wherein said cooking system executes said selected boiling program in accordance with said one or more input parameters.

[0030] In an embodiment of the invention, said one or more input parameters are selected from the list of an amount of said liquid, a boiling intensity, a temperature limit, a power limit, a lid status of said cookware, and a type of liquid.

[0031] The selected boiling program, and indeed every boiling program of the plurality of cooking programs, may comprise one or more input parameters relating to boiling of the liquid. By relating to the boiling of the liquid it may be understood that the input parameters denote physical quantities that affect the boiling process. Furthermore, by virtue of being “input parameters” it may be understood that the parameters may be provided or input to the cooking system prior when prior to, or during execution of the selected boiling program.

[0032] An input parameter of the one or more input parameters may be an amount of said liquid. For example, the user may input, using the input interface, an amount of liquid contained in the induction cookware. Providing the amount of liquid contained in the cookware may be useful for the selected boiling program in determining the necessary heat-up power and / or the necessary maintenance power.

[0033] Another input parameter of the one or more input parameters may be a boiling intensity. The boiling intensity may range from little to none bubbles in the liquid (useful for handling delicate food items, such as when poaching eggs) to large and vigorous bubbles (useful for handling food items that have a tendency to stick, such aswhen cooking pasta). The boiling intensity input parameter may be selected using the user interface for example by the user choosing among various graphical representations of boiling intensities.

[0034] Another input parameter of the one or more input parameters may be a temperature limit. The cooking system may know when the temperature limit is reached using measurements of temperature provided by the one or more temperature sensors of the cookware. The temperature limit may for example be provided by the user typing in a numerical value, or selecting among predefined settings, using the user interface.

[0035] Another input parameter of the one or more input parameters may be a power limit. By a power limit is understood a limit of the cooking power provided to the cookware by the cooking hob, or alternatively a limit on the power density provided to the cookware by cooking hob. The power limit may for example be provided by the user typing in a numerical value, or selecting among predefined settings, using the user interface.

[0036] Another input parameter of the one or more input parameters may be a lid status of the cookware. By a lid status is understood if the cookware has a lid placed thereon or not. The lid status may for example be provided by a user pressing a toggle switch in the user interface - the toggle switch may be toggled between the settings “lid on” and “lid off’. Providing a lid status is advantageous in that the boiling program may better adapt to the present conditions of the cookware and for example avoid boiling over of the liquid.

[0037] Yet another input parameter of the one or more input parameters may be a type of liquid. The type of liquid may be expressed in terms of viscosity, as some types of liquid are more viscous than others. For example, oil has a higher viscosity than water. The type of liquid may also be expressed in terms of salt content as the presence of salt may affect boiling of the liquid.

[0038] In an embodiment of the invention, said one or more input parameters are configurable, and wherein said step of selecting a boiling program among a plurality of cooking programs comprises providing said one or more input parameters.

[0039] The input parameters may be configurable, meaning that any given input parameter may be changed, for example a numerical value of the input parameter may be changed, or a status of the parameter may be changed. For example, an input parameter such as an amount of liquid may be configured by typing in a specific amount of liquid in litres, decilitres or millilitres, or an input parameter such as lid status may be configured by changing a state of the parameter, for example changing a lid status from “lid off’ to “lid on”.

[0040] In an embodiment of the invention, said one or more input parameters are provided by said user using a user interface.

[0041] The input parameters may be provided by the user using a user interface, preferably using a graphical user interface.

[0042] In an embodiment of the invention, said cooking system comprises a digital memory arranged in said cookware, said cooking hob or in an external device.

[0043] The memory may be any kind of digital memory from which a data processor controlling the preparation of food, including the inductive power, may have access to. Based on the access to the memory, the data processor may have access to temperature settings, time durations, boiling programs, cooking programs, etc. The external device may include a tablet, smart phone, cloud service, etc. Accordingly, the cooking programs may be stored in one of the cookware, cooking hob or external device.

[0044] In the context of the present invention, a “cooking system” is understood as a system comprising at least one cooking hob and at least one cookware.

[0045] In the context of the present invention, the term “cookware” is understood as any kind of cooking receptacle or cooking vessel in (or on) which food is placed when being cooked. The term cookware may thus encompass any type of cooking receptacleor cooking vessel including cooking pots such as sauce pots, stock pots and stew pots and cooking pans such as saucepans, saucier pans, saute pans, frying pans, grill pans and wok pans. Furthermore, within the context of the present invention, the term “cookware” is understood as any kind of cooking receptacle or cooking vessel arranged to be placed on a cooking hob for the purpose of cooking food.

[0046] By the term “cooking hob” may also be understood a cooktop or a stove. A cooking hob may provide heating to cookware placed thereon through different heating mechanisms depending on the type of the cooking hob. A gas hob delivers heating energy through burning of a gas, a ceramic hob delivers heating through heat radiation, and an induction hob delivers heating through induction.

[0047] According to an embodiment of the invention, the cooking system is an induction cooking system, and in this case the cooking hob and cookware may also be referred to as induction cooking hob and induction cookware.

[0048] A cooking program may include one or more generic boiling programs, one or more specific boiling programs and other predetermined programs for controlling heat and boiling intensity of a liquid contained in a cookware. Examples of generic boiling programs are 1, 2, 3, 4, 5 or more different boiling programs. The difference between the generic boiling programs is the boiling intensity. Examples of specific boiling programs are 1, 2, 3, 4, 5 or more different point programs. The difference between the specific boiling programs is that one may control the heating towards a target temperature and target boiling intensity to cook rice, another to cook potatoes, another to heat vegetables, etc.

[0049] As mentioned, the cookware comprises one or more temperature sensors. In a preferred embodiment, the one or more temperature sensors are arranged in the base part of the cookware. In another embodiment of the invention, the one or more temperature sensors are arranged in a sidewall of the cookware. In yet another embodiment of the invention, a plurality of temperature sensors are arranged in both the base part of the cookware and in a sidewall of the cookware. By the term “temperature sensor” is understood any kind of sensor which is capable of establishinga measure that is representative of a temperature of the cookware. The measure may be a direct measure of temperature, or it may be a measure from which a temperature is derivable or deducible from. Examples of temperature sensors include resistive temperature detectors (RTD), thermocouples and thermistors.

[0050] The temperature sensor may be an internal temperature sensor i.e. positioned in the interior of the cookware such as in a space established for the purpose in the base part of the cookware or along the side of the cookware. Thus, in an embodiment, the one or more temperature sensors are arranged in the base part of the cookware. For example, a single temperature sensor is arranged in the base part of the cookware, and in another example a plurality of temperature sensors, such as two or three temperature sensors, are arranged in the base part of the cookware.

[0051] In an embodiment of the invention, said user, via said user interface, is able to determine if the cooking process is to be performed with or without a lid on the cookware.

[0052] The user interface may be an interface arranged on the cookware, on the hob or on an external control device. Being able to select or deselect use of a lid is advantageous in that the performance of the selected cooking program may be improved, as the cooking program may take into account whether or not a lid is present on the cookware. Using a lid when cooking will in general lead to power savings as less heat escapes from the cookware. However, if power sufficient for boiling using no lid is applied to a cookware having a lid, the content of the cookware may very likely boil over. Therefore, taking into account the presence of a lid by allowing a user to select / deselect use of a lid is advantageous in that boiling over of the liquid may be avoided. Furthermore, taking into account the presence of a lid by allowing a user to select / deselect use of a lid is advantageous in that undesired boiling intensities may be avoided. This is clear since if a lid is placed on the cookware, and the system cannot distinguish between the situation with a lid and the situation without a lid, more power than the steady state power required to maintain a desired boiling intensity may be applied to the cookware and a too-high boiling intensity is reached.

[0053] In an embodiment of the invention, said user, via said user interface can adjust parameter settings in said plurality of cooking programs.

[0054] This is advantageous in that it has the effect, that the user may adapt default values of cooking programs to match own preferences. A parameter setting may include time and / or temperature setting which if changed increase or decrease the duration of heat at a specific temperature during a cooking program.

[0055] Further, via the user interface, the user may create a user-defined cooking program by specifying parameter settings according to own preferences and maybe also cookware e.g., for establishing a user-defined egg boiling program.

[0056] In an embodiment of the invention, said user, via said user interface, can select a cooking program among a plurality of cooking programs of said cooking system, each cooking program of said plurality of cooking programs being for a respective boiling intensity of said liquid contained in said cookware.

[0057] A boiling program is selectable by a user of the cooking system, such as selectable among a plurality of different cooking programs. By a boiling program may be understood a cooking setting pertaining to boiling conditions / intensity in the cookware. Since, the boiling program is selectable by a user, it may be referred to as a user-selectable boiling program.

[0058] In an embodiment of the invention, said plurality of cooking programs include at least 1, 2, 3, 4 or 5 boiling programs.

[0059] Having more than one boiling program is advantageous in that it has the effect, that a user can initiate cooking of any food item including heating to a boiling temperature without looking after and adjusting the heat applied to prevent spill. Hence, automatic boiling of e.g., pasta is facilitated without the risk of the liquid heating up and boiling over and thereby flowing over the edge of the cookware.

[0060] In an embodiment of the invention, said plurality of cooking programs comprises two or more boiling programs including a first boiling program and a secondboiling program, and wherein said first boiling program and said second boiling program are different with respect to boiling intensity.

[0061] In an embodiment of the invention, the maintenance power of at least one boiling program of said plurality of cooking programs by default requires a lid on said cookware.

[0062] Using a lid when boiling liquids is advantageous in that the steady state power required for maintenance of desired boiling intensity is reduced by a factor of roughly five compared to boiling in a cookware without liquid. Accordingly, by default the steady state power for a given boiling program is determined under precondition that the cookware comprises a lid during cooking.

[0063] Maintenance power, or steady state power, should be understood as the power supplied to the cookware from the cooking hob to maintain the predetermined boiling intensity (and temperature) of the liquid specified by the selected boiling program.

[0064] In an embodiment of the invention, the maintenance power of at least one of said boiling programs are depending on a type of said cookware.

[0065] Determining the maintenance power / steady state power (or power density, e.g., power per square centimeter of the base plate) provided from the cooking hob to the cookware based on the type of cookware is advantageous in that it optimizes the cooking process. The optimization is based on knowledge of diameter of the cookware, hence the larger the base plate diameter, the higher power can be applied and / or the longer time high power can be applied and vice versa.

[0066] In an embodiment of the invention, said plurality of cooking programs comprises at least 2, preferably at least 3, most preferably at least 4 generic boiling programs.

[0067] In an embodiment of the invention, said plurality of cooking programs comprises at least 1, preferably at least 2, most preferably at least 3 specific boiling programs.

[0068] Generic boiling programs are advantageous in that they have the effect, that liquid can be brought to boiling at different boiling intensity and hence, suitable for automatic cooking of different types of food requiring different boiling temperatures and boiling intensities for obtaining the optimal cooking result.

[0069] Specific boiling programs are advantageous in that they have the effect, that they are suitable for cooking foodstuff such as broccoli, rice and pasta automatically following the temperature rise of the food item resulting in the optimal cooking result.

[0070] In this context, “automatic” should be understood in that a cooking process may be initiated by a user but at least carry on automatically without the need of further involvement from the user until the cooking process is finished.

[0071] The boiling programs each bring the liquid to a boiling phase from a preboiling phase, without boiling over of the liquid, or burning in the case of e.g., milk.

[0072] In an embodiment of the invention, said selected boiling program comprises said pre-boiling phase and a boiling maintaining phase.

[0073] During the pre-boiling phase, liquid in the cookware is brought to boiling, and during the boiling maintaining phase the boiling intensity and temperature of the liquid is maintained. The power used to maintain the liquid at correct boiling intensity during the boiling maintaining phase of the boiling program is referred to as steady state power, maintenance power, or target power.

[0074] As mentioned, several boiling programs may exist, each associated with a respective boiling intensity to be maintained for the particular boiling program. The present invention differentiates between boiling intensity because different food items require different conditions for optimal cooking. In order to at least maintain the boiling intensity associated with the boiling program the cooking hob may maintain a given power (the steady state power), apply power in discrete time periods, or a combination thereof.

[0075] In an embodiment of the invention, said pre-boiling phase and a timer initiates when said user initiates said user-selected boiling program.

[0076] A timer is initiated when the user-selected boiling program is initiated, thus simultaneously with power provided to a cooking zone of the cooking hob on which the cookware is positioned. By a timer is understood any technical implementation capable of performing a timing operation similar to that of a stopwatch. The timer may preferably be implemented digitally, such as in one or more devices / units constituting the cooking system on which the method is carried out, such as the cooking hob, the cookware, or another electronic device. Initiating a timer when initiating a boiling program is advantageous in that the boiling process of the boiling program may at least be timer-controlled. A timer-controlled operation may ensure that sufficient power is supplied to the cookware, which is otherwise more difficult to ensure if the power supply is dictated solely on the basis of temperature measurements performed by the one or more temperature sensors of the cookware.

[0077] In an embodiment of the invention, said pre-boiling phase and a joule counter initiates when said user initiates said user-selected boiling program.

[0078] A joule counter may be initiated when the user-selected program is initiated, thus simultaneously with power provided to a cooking zone of the cooking hob on which the cookware is positioned. By a joule counter is understood any technical implementation capable of measuring / detecting energy (in units of joules) supplied to the cookware by the cooking hob. The joule counter may be used as an alternative to a timer, in the sense that it is capable of establishing an equivalent measure of time given that a constant power is provided to the cookware by the cooking hob over the time period of measuring (or given that the average power is known throughout the time period of measuring). As the joule counter is capable of being used to measure time, given knowledge of constant or average power supplied, the joule counter may therefore also be used to monitor the timing of the timer-controlled period. Although the term joule counter is used in this embodiment, it should be noted that the energy supplied to the cookware may also be measured / detected in other units of energy according to other embodiments of the invention.

[0079] In an embodiment of the invention, said boiling program comprises a timer- controlled period.

[0080] In an embodiment of the invention, said boiling program comprises a temperature-and-power-controlled period.

[0081] By a timer-controlled period is understood a time period of the boiling program in which control of the power supplied to the cookware is at least based on a state of the initiated timer. The timer-controlled period may be in the pre-boiling phase. For example, this control may imply that a certain power, e.g., above the maintenance power associated with the boiling program, is applied as long as the timer value is within a pre-set time range. By a temperature-and-power controlled period is understood a time period of the boiling program in which the control of the boiling program is delegated to control routines which take into account temperature, e.g., measurements of temperature provided by the one or more temperature sensors, and power to be supplied to the cookware, such as a maintenance power dictated by settings of the boiling program. Thus, the temperature-and-power controlled period may be in the boiling maintenance phase. In a preferred embodiment, the boiling program is divided into the timer-controlled period and the temperature-and-power controlled period which are subsequent and independent time periods of the boiling program.

[0082] Having both a timer-controlled period and a temperature-and-power- controlled period is advantageous in that a known problem relating to boiling of salt containing liquids may effectively be overcome. When even a minor part of the liquid contained in the cookware comprises salt, there is a tendency of this part of the liquid / water column to separate due to density differences between the minor part and the rest of the liquid / water in the column. The minor, and salty part gathers in the lower most part of the water column towards the base plate. Accordingly, this minor lower part of the column is being heated first when power is provided to the base plate of the cookware. However, it turns out, that the power supplied to the cookware is primarily deposited in the lower part of the column to raise the temperature of the salty part closest to the base plate and temperature sensor(s).

[0083] In embodiments where the one or more temperature sensors are arranged in the base part of the cookware, temperature measurements may be more representativeof actual temperatures in the lower / minor part of the liquid / water column than the actual temperatures of the remaining part of the liquid above. The heat capacity of saltwater is lower than the heat capacity of unsalted water, therefore saltwater heats up quicker than unsalted water. This contributes to the effect that the liquid above the minor / lower part will not be heated at all or will only be heated very slowly. As measurements by the one or more sensors better reflect the actual temperatures of the lower part of the column, and the boiling temperature of salt water is generally higher than that of the non-salted water, there is a high risk that the non-salted water will never reach a boiling state having a specific boiling intensity as dictated by the boiling program, or it will take a very long time, e.g., more than one hour to reach the maintenance boiling state, if the control routines are only based on measurements of temperature provided by the one or more temperature sensors. By having a first timer- controlled period of the boiling program it is possible to apply sufficient power for a sufficient amount of time to ensure that the salty part of the liquid actually reaches a state of boiling such that it mixes with the remaining part of the liquid. Once this has occurred, temperature measurements by the one or more temperature sensors better reflect the actual temperature of the total liquid volume in the cookware, and the temperature measurements may better be used to confirm that the temperature conditions for boiling according to the boiling program are reached. These measurements of temperature are then handled by the control routines of the temperature-and-power controlled period.

[0084] In an embodiment of the invention, said timer-controlled period terminates after at least 20 seconds, preferably after at least 30 seconds, most preferably after at least 40 seconds.

[0085] The timer-controlled period terminates after at least 20 seconds, preferably after at least 30 seconds, most preferably after at least 40 seconds. Thereby a sufficient time period is provided for the lower part (salty part) of the liquid to reach a state of boiling upon application of heating power, such that stirring of the liquid occurs.

[0086] Upon termination of the timer-controlled period, the temperature-and-power controlled period begins, where power provided to the cookware is controlled based at least on measurements provided by the one or more temperature sensors.

[0087] According to an embodiment of the invention, the duration of the timer- controlled period depends on the size of the cookware.

[0088] In an embodiment of the invention, power provided to said cookware during said timer-controlled period is above 1000 watts, such as above 1500 watts, preferably above 1800 watts, most preferably above 2000 watts.

[0089] Applying maximum cooking hob power, or above 1000 watts, above 1500 watts, above 1800 watts, or even above 2000 watts in the initial phase / timer-controlled duration of all boiling programs is advantageous in that the boiling programs may ensure fast heating of the liquid and thus a fast cooking process. Additionally, to being fast, the cooking process may also become suited for specific types of food items. Specifically, it may be avoided that some food items dissolve but instead these are cooked properly.

[0090] In an embodiment of the invention, power provided to said cookware is reduced if the one or more temperature sensors measures a temperature of at least 110 degrees Celsius during said timer-controlled period.

[0091] The power provided to the cookware may be reduced, such as turned off, if the one or more temperature sensors detect a temperature of at least 110 degrees Celsius, such as at least 120 degrees Celsius, such as at least 130 degrees Celsius, for example at least 150 degrees Celsius, during the timer-controlled period. This is advantageous to avoid heating up a cookware with no or only a minimum of liquid and thereby eliminating the risk of damaging the cookware or destroying / burning the food being prepared.

[0092] In an embodiment of the invention, said temperature-and-power-controlled period is initiated at least upon said one or more temperature sensors measuring atemperature that is at or above a predefined threshold temperature of said user-selected boiling program following a reduction in measured temperature.

[0093] During the timer-controlled period of the user-selected boiling program the measured temperature quickly rises from low temperatures of the pre-boiling phase, and in some conditions the measured temperature may very well exceed 100 degrees Celsius, however, this temperature progression is typically followed by a substantial reduction in measured temperature. This drop in measured temperature can be attributed to a convection process occurring in the liquid, where the lower part of the liquid (i.e., high salt concentration part) is boiling and thereby stirring the entire liquid such that a mixing of the entire liquid volume occurs. The mixing of the hot saltcontaining part of the liquid with the remaining colder part of the liquid has the effect that a new temperature of the liquid is achieved. The new temperature is significantly lower than the previously detected temperature present prior to boiling of the lower part of the column. As power is provided from this point on, the temperature of the total liquid volume increases, and measurements provided by the one or more temperature sensors may be more representative of actual temperatures of the entire liquid volume.

[0094] Therefore, once a threshold temperature has been reached following a reduction in measured temperature, the temperature-and-power-controlled period can be initiated. This has the effect that the power required for maintaining a specific boiling intensity is only applied once conditions are fulfilled such that the desired boiling intensity will actually be realized.

[0095] In an alternative embodiment of the invention, the temperature-and-power- controlled period is initiated at least upon said one or more temperature sensors detecting a rate of change of temperature which is at or above a predefined threshold rate of said user-selected boiling program following a reduction in measured temperature. By rate of change of temperature is understood a time derivative of temperature.

[0096] In an embodiment of the invention, termination of said temperature-and- power-controlled period is predefined by said boiling program or wherein a user terminates said temperature-and-power-controlled period via a user interface.

[0097] The cooking programs including the boiling programs may terminate after a predetermined time period at the boiling temperature. Such predetermined time period may be specified in the boiling program or a user may specify it via the user interface. Upon termination of the temperature-and-power-controlled period the heating power provided to the cookware by the cooking hob is reduced or completely cut off. Alternatively, the cooking / boiling program may specify a time period subsequent the temperature-and-power-controlled period where the temperature of the cookware is kept at a lower level to maintain the food item in the cookware at a certain heat.

[0098] In an embodiment of the invention, power provided to said cookware during said boiling maintenance phase comprises at least two powers including a first power and a second power, wherein said second power is greater than said first power.

[0099] In an embodiment of the invention, said user-selected boiling program is arranged such that said cooking hob repeatably alternates between providing said first power and providing said second power.

[0100] In an embodiment of the invention, said second power is provided with a lower duty cycle than said first power.

[0101] During the boiling maintenance phase, the cooking hob may supply different powers (or power densities) to the cookware, including a first power (or power density) and a second power (or power density), where the second power is greater than the first power. The first power may be the power required to maintain the desired boiling intensity according to the user-selected boiling program, and the second power is used to increase the boiling intensity for a limited period of time. By alternating between the first power and the second power it is made possible to cause intermittently stirring of the liquid contained by the cookware without any user involvement. This is particular advantageous for boiling programs of low boiling intensity where the boiling itself does not cause sufficient stirring of the liquid. The second power is preferablyprovided with a lower duty cycle than the first power to ensure that the boiling action is predominantly dictated by the first power which specifies the intended boiling intensity of the user-selected boiling program.

[0102] In an embodiment, the first power may be very low, such as close to zero, or indeed zero. In such an embodiment, the maintenance power dictated by the user- selected boiling program may represent an time-average power of first power and the second power.

[0103] This intermittent boiling achieved by alternating between two different power levels is advantageous in that power consumption may be reduced while providing sufficient stirring to accurately cook the food.

[0104] In an embodiment of the invention, the method according to any of the preceding provisions is carried out using a cooking system according to any of the following provisions.

[0105] Another aspect of the invention relates to an induction cooking system comprising an induction cooking hob, an induction cookware containing a liquid and a user interface, said induction cookware comprising at least a base part for placing on said induction cooking hob, one or more temperature sensors, a power supply and a transmitter, wherein said induction cooking system is configured for heating said liquid to boiling from a pre-boiling phase according to a boiling program, selectable by a user via said user interface, among a plurality of cooking programs of said induction cooking system, wherein said induction cooking system is configured for applying power to said induction cookware via said induction cooking hob to raise a temperature of said induction cookware, wherein said power includes a heat-up power and wherein said induction cooking system is configured for automatically applying said heat-up power to said induction cookware in said pre-boil phase on the basis of said user-selected boiling program, andsubsequently automatically reducing said applied power to a maintenance power determined by said user-selected boiling program.

[0106] Thereby is provided an advantageous induction cooking system which is advantageous for at least the same reasons as why the method is advantageous.

[0107] In an embodiment of the invention, said induction cookware comprises a plurality of temperature sensors.

[0108] The induction cookware may comprise a plurality of temperature sensors, such as two or more temperature sensors, for example two or three temperature sensors. Increasing the number of temperature sensors is advantageous in that the induction cookware may better represent temperatures of the induction cookware, and redundancy of the system is improved, as failure of one temperature sensor may not be detrimental to the continued use of the system.

[0109] In an embodiment of the invention, said induction cooking system comprises a controller for controlling said induction cooking system.

[0110] The induction cooking system may comprise a controller for controlling the induction cooking system. The controller may be implemented in any of the induction cooking hob, the induction cookware, or an external control device (external from the induction cooking hob and induction cookware). The external control device may be a dedicated control device or be facilitated by a handheld electronic device such as a smartphone, an electronic tablet, a laptop, a smartwatch or any other suitable computing device. Having the controller in an external control device is advantageous in that the cooking process may be remotely controlled.

[0111] In an embodiment of the invention, said induction cooking system according to any of the preceding provisions is configured to carry out a method according to any of the preceding provisions.

[0112] The induction cooking system according to this aspect of the invention may comprise any system features explained in relation to the previous aspect of the invention concerning a method of heating a liquid.The drawings

[0113] For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts. The drawings illustrate embodiment of the invention and elements of different drawings can be combined within the scope of the invention: fig. 1 illustrates an induction cooking system according to an embodiment of the invention, figs. 2a-c illustrate the smart cookware of fig. 1 in further details according to an embodiment of the invention, fig. 3a-c illustrate implementation of boiling programs in an induction cookware according to three different embodiments of the invention, figs. 4a-b illustrate processes of boiling unsalted water and salted water useful for understanding the present invention, fig. 5 illustrates a method according to an embodiment of the invention, figs. 6-7 illustrate respective flow charts of control of the power and thereby the heating of the liquid contained in the cookware according to an embodiment of the invention, and fig. 8 illustrate selection of a boiling program according to embodiments of the present invention.Detailed description

[0114] The present invention is described in view of exemplary embodiments only intended to illustrate the principles and implementation of the present invention. The skilled person will be able to provide several embodiments within the scope of the claims.

[0115] Fig. 1 illustrates a cooking system 1 according to an embodiment of the invention. The cooking system 1 of this embodiment is an induction cooking system 1 comprising an induction hob 2 (sometimes simply referred to as hob or cooking hob) and an induction cookware 3 (sometimes simply referred to as cookware). Note that the hob and cookware does not necessarily need to be an induction hob for implementing the present invention. Hence below a reference to an induction hob / induction cookware may be a reference to any type of hob and cookware, such as ceramic hobs and gas hobs, and cookware suitable for cooking on such cooking hobs.

[0116] The induction hob 2 comprises a power supply 4 supplying electric power to a controller 5 and an induction coil 6 from an external electric power source 19. The controller 5 is programmed to control the power supplied to the induction coil 6 and thereby the heating of an induction cookware 3 placed at an area of the hob 1 positioned over the induction coil 6 (sometimes referred to as coil). The area referred to may also be referred to as a cooking zone. Although a single induction coil 6 is seen in fig. 1, the cooking zone may according to another embodiment be associated with a plurality of induction coils (such a cooking hob is referred to as a free induction hob).

[0117] The hob 2 further comprises a user interface 7 via which the user may communicate with the controller 5 and thereby control the temperature development of heating of food items located inside the cookware 3. The user interface may be integrated in the hob 2 and implemented as a touch panel including a display for illustrating to a user which part of the hob 2 that is controlled and to what heating step of a predetermined number of heating steps that part is controlled.

[0118] The hob 2 further comprises a wireless communication module 8 via which the induction system 1 is able to communicate (in embodiments bidirectionally) withan external control device 9 (sometimes simply referred to as external device) which may be portable such as a tablet, smartphone, smart speaker, cloud service, etc. The wireless communication module 8 may support one or more communication standards such as Wi-Fi, Bluetooth, Infrared, etc. In this way the hob 2 can be controlled and / or configured from a remote location e.g. via a wireless network. In particular, the induction cooking system 1 is controlled via the external control device, on which a user can select a cooking program to be automatically executed among a plurality of cooking programs. The plurality of cooking programs include one or more boiling programs which will be described in greater detail below.

[0119] The controller 5 may be implemented as any suitable data processor or combination thereof such as a microprocessor or programmable logic controller. The controller 5 may comprise or communicate with a digital memory 10 from where the controller 5 may retrieve operation parameters, heating profiles, power levels at predefined heating steps, long-term cooking templates including recipes, etc.

[0120] As indicated, a hob 2 according to the present invention can be controlled according to a number of predefined heating steps each associated with a predefined power level for heating the cookware 3 positioned above the induction coils 6. In addition, to such traditional heating control, the hob 2 is able to heat a smart cookware 3 and thus perform intelligent / smart heating control, including execution of cooking programs, including one or more boiling programs.

[0121] Fig. 2a-c illustrates the smart cookware 3 of fig. 1 in further details according to an embodiment of the invention. Fig. 2a illustrates a perspective view of the induction cookware 3, fig. 2b illustrates an interior view of the induction cookware 3, and fig. 2c illustrates an inside view of a base part 11 of the induction cookware 3.

[0122] The induction cookware 3 as seen in fig. 2a is an induction cooking pan in the form of a saucepan having a handle 12 but could be any type of cookware. The induction cookware 3 comprises a base part 11 which is the part of the induction cookware 3 that is placed on an induction hob 2 during cooking. As seen in fig. 2b, the induction cookware 3 comprises a cooking surface 13, which is where the base part 11comes into contact with food items 14 during cooking. The induction cookware 3 comprises a data processing unit 15, a transmitter 16 and a power supply 17 in the form of a battery, all arranged within the handle 12 of the induction cookware 3.

[0123] It should be noted that a digital memory (not illustrated) may also be included in the handle 12 either as a standalone module communicating with the data processing unit 15 or as part of the data processing unit 15. Note that the induction cookware 3 may also comprise a dedicated compartment for enclosing the data processing unit 15, transmitter 16 and power supply 17 if not located in the handle.

[0124] The induction cookware 3 comprises a temperature sensor 18 (sometimes referred to simply as sensor) which is arranged within the base part 11, as seen in fig. 2c. The presence of one temperature sensor 18 does not exclude the possibility of the presence of further temperature sensors, and according to another embodiment of the invention the induction cookware comprises a plurality of temperature sensors arranged in the base part 11 of the cookware 3, such as two or more temperature sensors arranged in the base part 11 of the cookware. In another embodiment, one or more temperature sensors may also be arranged in a sidewall of the induction cookware.

[0125] Accordingly, when a food item 14 is to be prepared, it is positioned on the cooking surface 13 and the cookware 3 is positioned on the hob 2. Then a user may use the user interface 7 to start a traditional cooking process by selecting one of a plurality of predetermined heating steps (e.g. 1-9, P or a “low power”). Alternatively, the user may use the external control device 9 to select a cooking program among a plurality of cooking programs including one or more boiling programs. The selected cooking program may be stored in the memory 10 of the cooking hob. In another embodiment of the invention the user may use the user interface 7 of the cooking hob to select a cooking program among a plurality of cooking programs including one or more programs

[0126] As already mentioned, the induction cooking system 1 is configured to automatically execute a user-selected cooking program among a plurality of cookingprograms including one or more boiling programs. The boiling programs are useful for bringing a liquid 20 contained in the cookware 3 into a state of boiling from a preboiling phase. A pre-boiling phase is a state at which no formation of bubbles has not yet occurred in the liquid. Figs. 3a-c illustrates the implementation of boiling programs in an induction cookware 3 according to three different embodiments of the invention.

[0127] Fig. 3a illustrates the cookware 3 which is also seen in fig. 1 and figs. 2a-2c. As seen in fig. 3a, the cookware 3 is filled with a liquid 20 which is undergoing a boiling process as defined by a boiling program. The boiling program is characterized by a boiling intensity at which few and small bubbles are formed. The bubbles seen in the figure arise from a conversion of liquid water in this example to gaseous water (the gas being the bubbles). Fig. 3b illustrates the same cookware 3 as in fig. 3a, however, the cookware 3 is operating according to another boiling program which specifies a greater boiling intensity than the boiling program in fig. 3a. The increase in boiling intensity is illustrated by the density and size of bubbles being greater than in fig. 3a. Fig. 3c illustrates the same cookware 3 as seen in figs. 3a-b, however the cookware 3 is here depicted operating according to yet another boiling program of even greater boiling intensity than the boiling programs of figs. 3a-b. A skilled person will appreciate that increasing the power supplied to the cookware will generally increase the boiling intensity.

[0128] It should be noted that the possible boiling programs are not limited to these three illustrative examples, and a skilled person will readily appreciate that many more boiling programs exists since the boiling intensity may be varied through variation of the power provided to the cookware 3 by the cooking hob 2.

[0129] Liquid 20 such as water contained in a cookware 3 can be viewed as a liquid column extending from a cooking surface 13 of the cookware to a top surface of the liquid body (see for example liquid column in figs. 3a-c). As power is provided to the cookware by the cooking hob, heating is provided to the bottom part of the cookware closest to the cooking hob which results in uneven heating of the vertical liquid column. Therefore, during heating of the liquid, a temperature gradient exists along the liquid column with the highest liquid temperature being at the bottom of the liquidcolumn and the lowest liquid temperature being at the top surface of the liquid column. The size of the temperature gradient depends on several factors, including the height of the liquid column, the heating power, and also the type of liquid. For example, the presence of salt in water can further exacerbate the temperature gradient as salt does not necessarily mix evenly throughout the liquid column and is generally present in higher concentrations near the bottom than at the top of the column. Salt water has a higher boiling point than pure (unsalted) water but also a lower specific heat capacity than pure water, and therefore saltwater heats up quicker than unsalted water. Salt will typically concentrate at the bottom of the liquid column and as saltwater heats up more easily than pure, water the presence of salt further increases the temperature gradient along the liquid column.

[0130] These factors are necessary to consider when heating liquids in a cookware, and, if not properly taken into account, it may lead to incorrect heating of the liquid i.e. an uneven temperature distribution in the water column. This is particularly a challenge to cookware comprising a temperature sensor, where, for practical reasons, the temperature sensor may be positioned near the bottom of the cookware such as in inside the base part of the cookware (see fig. 2c). If the temperature sensor is placed near the bottom part of the cookware, and thereby near to the bottom part of the liquid column, measurements by the temperature sensor are not necessarily representative of the entire liquid body due to the temperature gradient. This means that portions of the liquid body, such as the top portions of the liquid body, may have an actual temperature that is lower than the temperature measured by the temperature sensor. This is particular problematic for cooking processes in which the heating power supplied to the cookware is based on inputs provided by the temperature sensor.

[0131] The above-described problem may be illustrated by means of an example illustrated in fig. 4a and 4b. Consider an induction cooking system 1 comprising a cookware 3 comprising a temperature sensor 18 mounted in the base part 11 thereof. A cooking hob 2 of the system supplies inductive power to the cookware 3 to raise the temperature thereof. In fig. 4a this is illustrated by a graph illustrating temperature curves of heating different volumes, from 0.5 L (litres) to 2.5 L (litres), of pure unsaltedwater. The graph depicts temperatures measured by the temperature sensor 18 in units of degrees Celsius as a function of time in seconds. A reference curve is included which represents an empty cookware (see solid line). The curves represent actual measurements performed using actual cookware. The power provided from the cooking hob 2 in this example is 1800W (watts). As seen from all the temperature curves depicted in fig. 4a, the measured temperature increases rapidly over the first 40 seconds. Most of the curves exhibit similar temperature developments over the first 100 seconds, the only real exceptions being the curves representing the empty cookware and the lowest liquid content of 0,5 L for which the measurement of temperature rises more quickly. For the cookware containing liquid (0,5 L - 2,5 L), the temperature curves reach an equilibrium temperature of about 110 degrees Celsius, however, the time of reaching that equilibrium temperature (or steady state temperature) depends on the liquid content. The greater the volume of water the longer it takes to reach the steady state temperature. It should be noted that the temperatures measured are not directly temperatures of the liquid since the temperature sensor is arranged in the base part of the cookware, and therefore the actual liquid temperatures are lower and closer to the boiling point of water (100 degrees Celsius at atmospheric pressure).

[0132] Fig. 4b illustrates temperature curves relating to heating of cookware (the same cookware used for establishing the temperature curves of fig. 4a). As seen in fig. 4b, there are curves representing an empty cookware and cookware filled with water in an amount of 0,5 L to 2,5 L. The cookware is also heated with a power of 1800 watts. The only difference to fig. 4a, is that the liquid used for the measurements of fig. 4b is saltwater. It is clearly seen that the curves representing the presence of saltwater (0,5 L to 2,5 L) does not exhibit the same temperature behaviour as seen in fig. 4a. From fig. 4b it is seen that the time of heating the saltwater to just around 110 degrees Celsius is more or less independent of the volume of saltwater. At this temperature, the water is not properly boiling even though the temperature sensor would suggest otherwise. The temperature measurements are more or less the same during the first approximate 40 seconds of heating. This is in fact due to the fact that the salt is concentrated at a lower portion of the cookware (or in a lower part of theliquid column). This portion of the liquid has a lower heat capacity than the remaining part of the liquid and is therefore heated more quickly. Thus, it is primarily the limited lower part that is heated, and this part represents substantially the same volume giving rise to a similar temperature behaviour.

[0133] A further effect of the presence of salt is seen from the curves. Take the curve representing 1,5 litres for example. After reaching a measured temperature of roughly 110 degrees Celsius, the measured temperature suddenly decreases to about 70 degrees Celsius, before climbing back up to an equilibrium temperature (steady state temperature) of 110 degrees Celsius. This sudden drop is attributed to the presence of salt in the liquid. Once the lower part of the liquid column (containing salt) is heated sufficiently, the salt water is brought to a boiling state at which a stirring of the entire liquid volume occurs. At this point in time the part of the water containing salt is mixed with the remaining (and colder) part of the liquid thereby cooling the base part of the cookware and giving rise to a reduction in the measured temperature. Once the temperature drop has occurred, the temperature steadily increases to the steady state temperature.

[0134] A skilled person will readily appreciate that the boiling of a liquid comprising salt may give rise to a specific problem for cookware 3 comprising a temperature sensor 18 arranged in a base part thereof. Even though the temperature sensor measures a temperature equal to or higher than the boiling temperature of the liquid, this does not mean that boiling of the liquid is actually occurring. The present invention is advantageous in that it solves this problem. A method which is a solution to this problem is illustrated with reference to Fig. 5.

[0135] Fig. 5 illustrates a method according to an embodiment of the invention. The method comprises method steps S1-S4.

[0136] In a first step SI, a cooking system 1 is provided. The cooking system comprises a cooking hob 2 and a cookware 3 comprising a liquid. The cookware comprises a base part 11 for placing on the cooking hob 2, one or more temperature sensors 18 arranged in the base part 11, a power supply 17, and a transmitter 16. Theinduction cooking system may be an induction cooking system 1 as depicted in fig. 1 In an alternative embodiment of the invention, the one or more temperature sensors may be arranged in a side of the cookware 3, and in yet another embodiment, a plurality of temperature sensors may be arranged in the base part of the cookware 3 and in a side of the cookware 3.

[0137] In a second step S2, a user selects a boiling program among a plurality of cooking programs of the cooking system 1. The selection may be carried out on an external control device 9 (see fig. 1). As an example, the selected boiling program may be any of the boiling programs described in relation to figs. 3a-c. The described way of selecting a boiling program is only understood as an example of selecting a boiling program, and indeed other ways of selecting a boiling program is conceivable within the scope of the claims. Such other ways include selecting a boiling program via the user interface 7 of the cooking hob 2 (see fig. 1).In a third step S3, power is applied to the cookware 3 using the cooking hob 2 to raise a temperature of the cookware, wherein the applied power includes a heat-up power which is automatically applied to the cookware in said pre-boil phase on the basis of said user-selected boiling program.In a fourth step S4, the applied power is automatically reduced to a maintenance power determined by the user-selected boiling program. Further details about specific implementations of the method are described in relation to figs. 6 and 7.

[0138] Fig. 6 illustrates a flow chart of control of the power and thereby the heating of the liquid contained in the cookware 3 according to an embodiment of the invention. As seen in fig. 6, the method of controlling power provided to the cookware 3 includes two phases: a heating up phase HP and a boiling maintaining phase MP. The heating up phase HP comprises steps S1-S5, and the temperature maintaining phase MP comprises steps S6-S7.

[0139] In a first step SI, a user selects a cooking program among a plurality of cooking programs. The selected cooking program is a boiling program and is selected using an external control device 9 (see fig. 1). The boiling program ensures that liquidin the cookware 3 is to be bought from a pre-boiling phase to boiling at a steady state temperature and boiling intensity. The temperature of the liquid in the beginning of the pre-boiling phase may be room temperature, fridge temperature, water tap temperature, etc.

[0140] The temperature of the liquid at the end of the pre-boiling phase i.e., when the boiling maintaining phase MP begins may be predetermined or the user may be allowed to adjust this temperature, at least in a user configurable boiling program. This temperature is also referred to as boiling temperature even though this temperature may not be equal to the scientific boiling temperature of the liquid, and even though, for the same liquid, several boiling programs with individual boiling temperatures may exist.

[0141] In a second step S2, a high power such as a maximum available power is provided from the hob 2 to the cookware 3. It may be the same high power that is provided independent on which boiling program the user selects because all boiling programs have the same purpose of bring the liquid to the boiling program specified boiling temperature and boiling intensity as fast as possible. With this being said, user- defined or specific boiling programs may control power otherwise. High power is above 1000 W (watts), preferably above 1300W such as between 1400W and 2000W.

[0142] In step S2, a timer is also initiated started by / in the controller 5. While the timer is counting (tested in step S3), the controller 5 does not use the temperature readings from the temperature sensor as input to the power regulation. This is to avoid that the control is based on a temperature measurement which is obtained before the reduction in measured temperature is obtained (see temperature drops in fig. 4b). Hence, as long as this timer has not reached its end value (i.e., the answer to the question “has the timer reached its end value? ” is no, represented by the letter N), the high power is continued to be provided to the cookware 3 (via the induction coil 6 of the hob 2 beneath the cookware 3). In an alternative embodiment, a joule counter is used instead of the timer. The joule counter is arranged to measure / detect energy supplied to the cookware 3 by the hob 2, and given an assumption of a constant power supply, or average power supply, over the time of measuring energy, it is possible toinfer a time in which power is supplied. This time may be equivalent to the time as provided by the timer, and therefore the joule counter can be used equivalently to the timer and for the same purpose.

[0143] With this said, it should be mentioned, that if the measured temperature rises to a value above 130 degrees Celsius, the power is reduced. This is because it would indicate that the cookware is empty and thus for safety reasons, and to protect the cookware, the power is turned off. However, the user may, via the user interface, actively force the hob to continue with increasing the heat of the cookware if e.g., the cooking of the food item therein requires so.

[0144] In step S4, temperature readings from the temperature sensor is compared to establish if the temperature is decreasing or increasing. Once it has been established that the temperature decreases, it indicates that convection has occurred in the liquid and the temperature of the entire water column can occur upon application of heat. If the temperature drop is detected (Y), the boiling maintaining phase MP is initiated. If not (N), additional heating with a high-power setting is provided for a fixed amount of time (see step S5).

[0145] In a next step S6, a predetermined maintenance power (or steady state power) is provided to the cookware 3 by the cooking hob 2. The predetermined maintenance power of this embodiment is specified by the user-selected boiling program, however according to another embodiment, the maintenance power may correspond to one or more predetermined power settings of the cooking hob. The supplied maintenance power is a constant power per area of the bottom of the cookware. Once the boiling program is finished (by timeout of a timer), a user terminates the boiling program, or initiates another cooking program, the boiling process initiated at step SI is terminated in step S7.

[0146] Fig. 7 illustrates a variation to the control method illustrated in fig. 6. The steps S1-S5 are the same, however, fig. 7 differs from fig. 6 in the boiling maintenance period MP. In step S6 a predetermined maintenance power (or steady state power) is provided to the cookware 3 by the cooking hob 2. The predetermined maintenancepower of this embodiment is specified by the user-selected boiling program, however according to another embodiment, the maintenance power may correspond to one or more predetermined power settings of the cooking hob. The supplied maintenance power is a constant power per area of the bottom of the cookware, however the power may be defined differently according to other embodiments of the invention including in units of power, for example watts. The power supplied in step S6 is only suppled during a pre-determined time duration, and next in step S7 a higher power is provided to the cookware for a time duration shorter than the time duration of step S6. The steps S6 and S6 repeats in an alternating way until the boiling program is terminated at step S8. The boiling program may be terminated in a similar way as seen in fig. 6. The application of short bursts of extra power (step S7) means that for brief moments the boiling intensity increases and stirring of the liquid is achieved. Thereby is achieved a cooking program capable of automatically stirring the liquid in the cookware, without need of human intervention. This is particularly advantageous for boiling programs of low boiling intensity where stirring of the liquid is not achieved through application of the maintenance power. Other advantages include power saving and avoiding boiling over as compared to a constant simmer at slightly higher power. According to another embodiment of the invention, the maintenance power represents a timeaverage of two different powers supplied in an alternating manner. In may therefore be that two different power levels are used; a first power level which may be very low, or even zero, and a second power level greater than the first power level. In such a scenario the power necessary for adequately maintaining a predetermined boiling intensity may predominantly be provided due to the second power.

[0147] Fig. 8 illustrates how a selection of a boiling program among a plurality of cooking programs is made according to embodiments of the present invention. The figure shows an external control device 9 in the form of a tablet computer (or tablet) displaying a user interface 7 using an electronic display of the tablet. The tablet forms part of an induction cooking system 1 (for example induction cooking system 1 shown in fig. 1). In this embodiment, the user interface 7 is referred to as a graphical user interface. The graphical user interface 7 displays a plurality of cooking programs including a first boiling program Pl and a second boiling program P2, however, a usermay view other cooking programs by scrolling through the horizontal list (illustrated with the horizontal progress bar). As seen, the user of the cooking system 1 has selected the first boiling program Pl to be executed using the induction cookware 3. A graphical representation of the induction cookware 3 is shown in the user interface 7 thereby showing the user the association of the induction cookware 3 with the selected boiling program Pl. Each of the plurality of boiling programs P1-P2 has associated input parameters 21-23 relating to boiling of a liquid. At least some of these input parameters are configurable. For example, a user may type in an amont of liquid in millilitres to be boiled using the first boiling program Pl. In this example, the input parameter relating to an amount of liquid 22 is chosen by the user to be 800 millilitres. Another input parameter 23 relates to the boiling intensity of the respective boiling program and is graphically represented by a size and a number of bubbles. The greater the amount and size of bubbles, the greater the boiling intensity. For example, the first boiling program Pl has a low boiling intensity suitable for e.g., poaching of eggs, whereas the second boiling program P2 has a high boiling intensity suitable for e.g., cooking of pasta. In the present embodiment, the boiling intensities of the presented boiling programs are pre-defined, however, as user may still configure the boiling intensity of the respective boiling programs by clicking on input parameter 23 in the user interface. Furthermore, each of the shown boiling programs comprises an input parameter 21 relating to a “lid status” which is represented by a toggle switch. The first boiling program Pl has a lid status which is “lid on” and the second boiling program P2 has a lid status which is “lid off’. The lid status input parameter 21 allows the user to select for any boiling program whether the boiling of the liquid is to be performed with a lid or not.

[0148] Once the boiling program Pl is selected, and necessary input parameters 21- 23 are filled in, the boiling program is automatically executed by the induction cooking system 1. It should be noted that the first boiling program Pl and the second boiling program P2 are merely examples of boiling programs and that boiling programs may differ in the number of input parameters. For example, a boiling program may comprise one or more input parameters, for example one or more of the shown input parameters as seen in fig. 8.List1 Induction cooking system2 Induction hob3 Induction cookware4 Power supply5 Controller6 Induction coil7 User interface8 Wireless communication module9 External control device10 Digital memory11 Base part of induction cookware12 Handle of induction cookware13 Cooking surface of induction cookware14 Food item15 Data processing unit of induction cookware16 Transmitter of induction cookware17 Power supply of induction cookware18 Temperature sensor of induction cookware19 External electric power source20 Liquid21 Input parameter - Lid status22 Input parameter - Amount of liquid23 Input parameter - Boiling intensityS1-S8 Method stepsHP Heating-up phaseMP Boiling maintenance phaseP1-P2 Boiling programs

Claims

Claims1. A method of heating a liquid to boiling from a pre-boiling phase, comprising the steps of:- providing a cooking system comprising a cooking hob and a cookware containing said liquid, said cookware comprising at least a base part for placing on said cooking hob, one or more temperature sensors, a power supply and a transmitter,- selecting, by a user, a boiling program among a plurality of cooking programs of said cooking system,- applying power to said cookware using said cooking hob to raise a temperature of said cookware; wherein said applied power includes a heat-up power which is automatically applied to said cookware in said pre-boil phase on the basis of said user-selected boiling program, and- subsequently automatically reducing said applied power to a maintenance power determined by said user-selected boiling program.

2. The method according to claim 1, wherein said cookware is an induction cookware and wherein said cooking hob is an induction cooking hob.

3. The method according to claim 1 or 2, wherein said cooking system comprises a user interface, wherein said user interface is comprised by at least one item from the list comprising: external electronic device, cooking hob and cookware.

4. The method according to any of the preceding claims, wherein said cooking system comprises a controller for controlling said cooking system.

5. The method according to any of the preceding claims, wherein said plurality of cooking programs comprises a plurality of boiling programs, and wherein said step of selecting a boiling program among a plurality of cooking programs comprises selecting a boiling program among said plurality of boiling programs.

6. The method according to any of the preceding claims, wherein said step of selecting a boiling program among a plurality of cooking programs comprises selecting said boiling program using said user interface.

7. The method according to any of the preceding claims, wherein said selected boiling program comprises one or more input parameters relating to boiling of said liquid, and wherein said cooking system executes said selected boiling program in accordance with said one or more input parameters.

8. The method according to claim 7, wherein said one or more input parameters are selected from the list of an amount of said liquid, a boiling intensity, a temperature limit, a power limit, a lid status of said cookware, and a type of liquid.

9. The method according to any of the claims 7-8, wherein said one or more input parameters are configurable, and wherein said step of selecting a boiling program among a plurality of cooking programs comprises providing said one or more input parameters.

10. The method according to claim 9, wherein said one or more input parameters are provided by said user using a user interface.

11. The method according to any of the preceding claims, wherein said cooking system comprises a digital memory arranged in said cookware, said cooking hob or in an external device.

12. The method according to any of the preceding claims, wherein said user, via said user interface can adjust parameter settings in said plurality of cooking programs.

13. The method according to any of the preceding claims, wherein said user, via said user interface, can select a cooking program among a plurality of cooking programs of said cooking system, each cooking program of said plurality of cooking programs being for a respective boiling intensity of said liquid contained in said cookware.

14. The method according to any of the preceding claims, wherein said plurality of cooking programs include at least 1, 2, 3, 4 or 5 boiling programs.

15. The method according to any of the preceding claims, wherein said plurality of cooking programs comprises two or more boiling programs including a first boiling program and a second boiling program, and wherein said first boiling program and said second boiling program are different with respect to boiling intensity.

16. The method according to any of the preceding claims, wherein a maintenance power of at least one boiling program of said plurality of cooking programs by default requires a lid on said cookware.

17. The method according to any of the preceding claims, wherein a maintenance power of at least one boiling program of said plurality of cooking programs are depending on a type of said cookware.

18. The method according to any of the preceding claims, wherein said plurality of cooking programs comprises at least 2, preferably at least 3, most preferably at least 4 generic boiling programs.

19. The method according to any of the preceding claims, wherein said plurality of cooking programs comprises at least 1, preferably at least 2, most preferably at least 3 specific boiling programs.

20. The method according to any of the preceding claims, wherein said selected boiling program comprises said pre-boiling phase and a boiling maintaining phase.

21. The method according to any of the preceding claims, wherein said pre-boiling phase and a timer initiates when said user initiates said user-selected boiling program.

22. The method according to any of the preceding claims, wherein said pre-boiling phase and a joule counter initiates when said user initiates said user-selected boiling program.

23. The method according to any of the preceding claims, wherein said boiling program comprises a timer-controlled period.

24. The method according to any of the preceding claims, wherein said boiling program comprises a temperature-and-power-controlled period.

25. The method according to any of the preceding claims, wherein said timer- controlled period terminates after at least 20 seconds, preferably after at least 30 seconds, most preferably after at least 40 seconds.

26. The method according to any of the preceding claims, wherein power provided to said cookware during said timer-controlled period is above 1000 watts, such as above 1500 watts, preferably above 1800 watts, most preferably above 2000 watts.

27. The method according to any of the preceding claims, wherein power provided to said cookware is reduced if the one or more temperature sensors measures a temperature of at least 110 degrees Celsius during said timer-controlled period.

28. The method according to any of the preceding claims, wherein said temperature- and-power-controlled period is initiated at least upon said one or more temperature sensors measuring a temperature that is at or above a predefined threshold temperature of said user-selected boiling program following a reduction in measured temperature.

29. The method according to any of the preceding claims, wherein termination of said temperature-and-power-controlled period is predefined by said boiling program or wherein a user terminates said temperature-and-power-controlled period via a user interface.

30. The method according to any of the preceding claims, wherein power provided to said cookware during said boiling maintenance phase comprises at least two powers including a first power and a second power, wherein said second power is greater than said first power.

31. The method according to any of the preceding claims, wherein said user-selected boiling program is arranged such that said cooking hob repeatably alternates between providing said first power and providing said second power.

32. The method according to any of the preceding claims, wherein said second power is provided with a lower duty cycle than said first power.

33. The method according to any of the preceding claims, wherein the method according to any of the preceding claims is carried out using a cooking system according to any the claims 1-32.

34. An induction cooking system comprising an induction cooking hob, an induction cookware containing a liquid and a user interface, said induction cookware comprising at least a base part for placing on said induction cooking hob, one or more temperature sensors, a power supply and a transmitter, wherein said induction cooking system is configured for heating said liquid to boiling from a pre-boiling phase according to a boiling program, selectable by a user via said user interface, among a plurality of cooking programs of said induction cooking system, wherein said induction cooking system is configured for applying power to said induction cookware via said induction cooking hob to raise a temperature of said induction cookware, wherein said power includes a heat-up power and wherein said induction cooking system is configured for automatically applying said heat-up power to said induction cookware in said pre-boil phase on the basis of said user-selected boiling program, and subsequently automatically reducing said applied power to a maintenance power determined by said user-selected boiling program.

35. The induction cooking system according to claim 34, wherein said induction cookware comprises a plurality of temperature sensors.

36. The induction cooking system according to claim 34 or 35, wherein said induction cooking system comprises a controller for controlling said induction cooking system.

37. The induction cooking system according to any of the claims 34-36, wherein said induction cooking system is configured to carry out a method according to any of the claims 1-33.

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