DK2445311T3

DK2445311T3 - Combination preparation device

Info

Publication number: DK2445311T3
Application number: DK11010244.9T
Authority: DK
Inventors: Ulrich Frey; Katrin Alder
Original assignee: V-Zug Ag
Priority date: 2011-12-28
Filing date: 2011-12-28
Publication date: 2017-07-31
Also published as: SI2445311T1; EP2445311B1; AU2012268875B2; AU2012268875A1; EP2445311A2; EP2445311A3; PL2445311T3

Description

Field of the Invention

The invention refers to a cooking device for cooking food and to a method for operating a cooking device .

Background

Steamers become increasingly popular due to their gentle cooking of the food. For this, steam is supplied to a cooking chamber in order to heat up the cooking chamber and the food located therein. EP 2 322 859 A1 shows a cooking device with an air outlet from the cooking chamber, which shall be improved with respect to known flap mechanisms. The cooking device can be heated with microwaves, heated air, steam or a combination thereof. A humidity sensor may be arranged in the air outlet. EP 2 083 223 A1 shows a cooking device with a steam generator, a hot air generator, a microwave generator and a bottom heat. A cooking chamber of the cooking device is aerated via a displaceable flap. The air outlet is closed during steam operation in order to avoid that steam condenses at the humidity sensor. JP 2006 284013 A shows a cooking device with a steam generator and a hot air generator as well as an air outlet from the cooking chamber of the cooking device .

Summary of the Invention

Object of the invention is to provide a cooking process and a cooking device further improving the introduced steaming process such that the cooking time is reduced and / or the result of cooking is improved.

The object is solved by cooking devices according to the features of the patent claim 1 and by a method for operating cooking devices according to the features of the patent claims 10.

According to a first aspect, the cooking device provides a cooking chamber for receiving the food.

In the context of the invention, cooking shall encompass all kinds of heating food, hence, the warming, the heating and the defrosting of food, dishes, liquids, etc. The cooking chamber typically is a hollow body open at one side, which cooking chamber also is referred to as muffle in the context of baking ovens, the open side of which is lockable by means of a door. In addition, a steam generator is provided which allows for supplying steam, and in particular water steam, into the cooking chamber. External steam generators shall be included, which generate steam outside the cooking chamber which steam is supplied into the cooking chamber, via a supply pipe. The claimed steam generator, however, shall also encompass internal steam generators, wherein the steam is generated inside the cooking chamber, for example by heating water.

In addition, the cooking device comprises an opening in the cooking chamber for allowing steam to escape from the cooking chamber. This opening may in particular be understood as an opening in addition to the door opening which allows an escape of steam even while the door is closed. Such an opening may, for example, have a diameter approximately as big as a coin.

In addition to the steam generator a micro-wave generator is provided for heating food in the cooking chamber. By means of providing two different heating modes for the food the present cooking device is a so-called multi function cooking device. Further, a control unit is provided for operating the cooking device, which preferably is an electronic control unit. The control unit receives inter alia the signal of a sensor measuring a parameter of steam escaping from the opening. This parameter may be the temperature of the steam escaping in case the sensor is a temperature sensor. This parameter may be the flow of the escaping steam in case the sensor is a flow sensor. This parameter may be the pressure of the escaping steam in case the sensor is a pressure sensor. This parameter may be the humidity of the escaping steam in case the sensor is a humidity sensor. The sensor may be a sensor combined from two or more of the previous individual sensors and hence may rely in its measuring result on two or more different physical parameters.

Preferably, the sensor is arranged at the opening itself or, however, in an extension of the opening, which is also referred to as mouth, which extension connects the cooking chamber with an external space outside the cooking chamber. The sensor may be arranged at an inner or an outer wall of the extension for measuring the parameter. The sensor, however, may also be arranged in the cooking chamber itself close to the opening. Even there the sensor can measure a parameter of steam escaping through the opening. The sensor may, for example, be arranged within a radius of at most 5 cm around the opening.

According to a further aspect of the invention a cooking device for cooking food provides a cooking chamber for receiving the food and a steam generator for supplying steam into the cooking chamber. A sensor is now provided for measuring a parameter of steam in the cooking chamber. Again, a microwave generator is provided for heating the food in the cooking chamber. A control unit controls the microwave generator dependent on the parameter measured by the sensor.

Here, instead of indirectly measuring the steam saturation in the cooking chamber by measuring the parameter of steam escaping from the cooking chamber a direct measure is taken for the steam saturation in the cooking chamber. This can in particular be achieved by a humidity sensor arranged in the cooking device which may, for example, detect a relative humidity in the cooking chamber. An opening may preferably still be available in the cooking chamber for allowing steam to escape.

The control unit on its part controls in both aspects the microwave generator dependent on the parameter measured by the sensor. The control may, for example, evoke one or more of the following actions: - Switching on the microwave generator; - Switching off the microwave generator; - Increasing the power of the microwave generator; - Decreasing the power of the microwave generator; - Determining an operation period for the microwave generator; - Extending an operation period for the microwave generator; - Shortening an operation period for the microwave generator; - Selecting a microwave programme; - Or others.

The control unit may in preferred embodiments be adapted to control the microwave generator dependent on one or more of the following events, also referred to releasing events or trigger events: - Exceeding a threshold by the parameter measured, which parameter typically is pre-processed as a sensor signal and transmitted to the control unit; - Falling below a threshold by the parameter measured; - Exceeding or falling below a threshold by a gradient of the parameter measured; - A pattern in the parameter measured; - Or others.

Adding the microwave function dependent on the steam escape signal shortens the cooking period; Switching off the microwave function dependent on the steam escape signal prevents from overcooking the food.

The sensor typically indirectly reflects a degree of the steam condition in the cooking chamber given that the more steam is in the cooking chamber the more steam will escape through the opening. On the other hand, hardly will escape any steam through the opening if there is only little steam in the cooking chamber or only little steam is supplied to the cooking chamber. The quantitative detection of the escaping steam may depend on the pressure conditions at the end of the opening and other factors which determine the internal pressure in the cooking chamber.

Insofar, the cooking process and the cooking result may be improved: For example, in a first operation mode it may be waited for adding the microwave until at least a defined steam level is reached in the cooking chamber, under the assumption that the steam primarily is seen as a transfer medium for the microwaves towards the food, such that the microwave generator may be operated at an improved measurability when steam is supplied previously. The result may be an improved absorption of energy by the food. Moreover, the power distribution may be improved and a local drying out of the food may be prevented. Insofar, in this first operation mode the cooking may start with a pure steam cooking. When the sensor, which may be embodied as a temperature sensor here, for example shows a certain temperature of the escaping steam which temperature exceeds a first threshold, the micro-wave generator is switched on upon exceeding this first threshold.

In a second exemplary operation mode a cooking of the food is primarily achieved by steam cooking. The addition of the microwave shall merely accelerate the steam cooking by either adding the microwave function at the beginning of the steam cooking, or when a certain cooking level is already achieved and a corresponding temperature at the sensor exceeds a second threshold. Here, the addition of the microwave is envisaged to shorten the cooking on the one hand. On the other hand, adding the microwave is beneficial for the cooking result, given that by adding the microwave in particular the inside of the food is heated while the steam cooking affects the food from the outside. The microwave may in the second operation mode, for example, be added only for a short period in time, possibly with maximum power.

The invention insofar combines steam cooking and microwave cooking in a preferred manner by controlling the microwave generator via a measure representing steam escaping from the cooking chamber. It was realized, that herewith the food may be heated faster and / or to a hotter temperature, and that the food moreover does not dry out as quickly. In addition, the excess remaining water may be reduced by means of the methods as proposed.

Preferably, the steam cooking may be applied in combination with adding hot air. All operation modes mentioned before may also be used for heating food anew.

The proposed operation of the cooking device may preferably be triggered by selecting a defined cooking programme by means of a selection switch. Such a selection programme may explicitly point to a combined steam and microwave cooking. Alternatively, the proposed operation may always be executed when one of the cooking programmes "steam cooking" or "microwave cooking" is activated by the user, for example by operating an optional key. The proposed operation may also automatically be activated when independent on the cooking programme either the steam generator or the microwave generator is activated. Preferably, the proposed operation may also be activated when the microwave generator and the steam generator are simultaneously activated.

According to a further aspect of the invention a method for operating a cooking device for cooking food comprises the supply of steam generated by a steam generator into a cooking chamber, the measurement of a parameter of steam escaping from the cooking chamber through an opening, and the control of a microwave generator dependent on the measured parameter.

According to another aspect of the invention a method for operating a cooking device for cooking food comprises the supply of steam generated by a steam generator into a cooking chamber, the measurement of a parameter of steam in the cooking chamber, and the control of a microwave generator dependent on the measured parameter. In this case, the humidity in the cooking chamber is preferably measured.

Preferred embodiments of the invention are characterized by the sub-claims.

Embodiments which are explicitly disclosed in connection with the cooking device shall be regarded as disclosed in relation to the method, too, and vice versa.

Brief description of the drawings

The embodiments defined above and further embodiments, features and advantages of the present invention can also be derived from the examples of embodiments to be described hereinafter in connection with the drawings in which the figures illustrate: FIG. 1 a cross section through a cooking device according to an embodiment of the invention, and FIG. 2 a schematic illustration of a cooking device according to a further embodiment of the invention .

Detailed description of the drawings

The cooking device according to FIG. 1 comprises a cooking chamber 1 being defined by walls 2 and a door 3. The cooking chamber may, for example, comprise a volume of 50 litres or more, for example 56 litres. The cooking device as illustrated may be operated as well as a steamer, as a microwave oven, and as a combined steam / microwave device. The cooking device comprises a schematically drafted steam generator 4 separate from the cooking chamber 1, the steam of which steam generator 4 is supplied to the cooking chamber 1 via a supply pipe. A microwave generator referred to by 31 schematically is arranged at a ceiling of the cooking chamber 1 and may, for example, supply a maximum power of 700 Watt. The cooking device may optionally be operated as a baking oven wherein it comprises a conventional resistive heater with a top heat 5a and a bottom heat 5b in a preferred embodiment. Alternatively, or in addition to the heater 5a, 5b the cooking device may be equipped with hot air or with a grill heater. A blower 6, for example a cross-flow blower is arranged outside the cooking chamber 1. The blower 6 supplies air from a suction compartment 7 into a pressure compartment 8. The supplied air escapes from the pressure compartment 8 through a front outlet opening 9 of the device into the environment. The pressure compartment 8 is limited at the top by means of an inclined cover plate 10 and at the bottom by means of an inclined base plate such that the pressure compartment 8 narrows towards the outlet opening 9. At its sides the pressure compartment 8 is defined by means of side walls (not shown). The cover plate 10 and the base plate 11 may, for example, alternatively be approximately aligned in parallel to each other. Other variants in construction may be conceivable.

In the ceiling of the cooking chamber 1 an opening 14 and a further opening 20 are arranged. The further opening 20 has a diameter of about 2.5 cm while the opening 14 preferably is smaller. The cooking device comprises an apparatus for measuring the escape of steam from the cooking chamber 1. This apparatus comprises the opening 14 which serves as a measuring opening and which leads from the cooking chamber 1 into the internal com- partment 15 of a protection housing 16. The protection housing 16 is arranged in the pressure compartment 8 and communicates therewith via a connection opening 17. The connection opening 17 is arranged at a side of the protection housing 16 which is averted from the protection housing 16. In the protection housing 16 a temperature sensor 18 is arranged at the mouth of the opening 14, for example in form of an NTC resistor which measures the temperature Tx. The opening 14 preferably is permanently open.

During operation of the cooking device the blower 6 preferably is permanently in operation. The blower sucks air from the environment through openings in the back wall and in side walls of the cooking device. Such air passes the sucking area 7, is blown into the pressure area 8 and leaves therefrom via the outlet opening 9. Given that the pressure compartment 8 narrows towards the outlet opening 9 a slight excess pressure occurs in the pressure compartment 8, i.e. a pressure being higher than the pressure in the environment, while the pressure in the sucking compartment 7 is lower. Hence, there should be a certain excess pressure in the cooking chamber 1 for detecting an increase in temperature at the temperature sensor 18 which may suggest a gas / steam escape through the opening 14. Another task of the blower 6 is to convey air which is heated at the outside of the cooking chamber 1 to the outside for cooling purposes.

For controlling the steam generator 4, the microwave generator 31 and further components of the cooking device a control unit 24 is provided which inter alia monitors the temperature signal from the temperature sensor 18. The steam generator 4 basically is controlled as follows: Once a cooking operation at least comprising steam cooking is set by a user at a user interface, such as a selection switch, the steam generator 4 is switched on and the steam generated is supplied to the cooking chamber 1. Owed to the above said an escape of steam from the cooking chamber 1 is hampered in view of the pressure conditions generated by the blower 6. Insofar, steam may only escape through the opening 14 once a steam pressure in the cooking chamber 1 exceeds the environmental pressure, which escaping steam may be detected by a temperature increase at the temperature sensor 18 and may also be detected in its quantity. If the temperature Tx measured exceeds a first threshold T1 the microwave generator is switched on. It is assumed that once certain pressure conditions are reached in the cooking chamber 1 which scenario is represented by the first threshold Tl, an addition of microwaves accelerates the desired cooking result and supports the steam cooking process.

The temperature signal of the temperature sensor 18 or, more generally the gas escape signal of the gas escape sensor preferably may be used for other purposes, too: For example, energy may be supplied to the steam generator 4 if the temperature Tx at the temperature sensor 18 falls below a bottom threshold Tu.

The further opening 20 may optionally be opened, too, if the temperature Tx at the temperature sensor 18 exceeds a top threshold To such that additional steam may be withdrawn from the cooking chamber 1. The further closable opening 20 connects the cooking chamber 1 with the sucking compartment 7 ahead of the blower 6. For closing the second opening 20 a lock is provided consisting of a baffle 22 which may be moved more or less far across the mouth of the opening 20 by a step or servo motor 23 such that the lock may be transferred from an open position into a closed position essentially in a continuous way. Intermediary positions if required can be achieved for a reduced throughput through the further opening 20 by repeatedly short-term opening and closing of the baffle 22, in the spirit of a pulse width modulation .

The temperature signal Tx of the temperature sensor may also be used for detecting a gas escape from the food itself which event may occur with food heated to approximately 90° degrees Celsius. Such gas escape from the food may on the one hand cause a steam escape from the cooking chamber which may be detected by the temperature sensor. Detecting such event may in turn allow for a more precise control of the future cooking process given that the timing of this event may allow for conclusions as to a volume, consistence, etc of the food. Escaping gases and steams may be removed by opening the further opening, excess pressure may be lowered for keeping the oxygen level in the cooking chamber low.

Moreover, a cooking chamber temperature sensor 25 may be provided in the cooking chamber 1 which may be used for measuring the temperature of the cooking chamber 25. Further, a core temperature sensor (not shown) may be provided, for example, in form of a needle which may be pierced into the food.

The microwave function may alternatively by controlled by a humidity sensor 26 in the cooking chamber 1 which detects the relative humidity in the cooking chamber 1.

The cooking device according to Figure 1 may be operated in different operating modes wherein the control unit 24 is to be provided with appropriate input elements which allow the user to select a desired programme. In particular, the device may be used as a cooking device in a conventional way, for example by input of a desired cooking chamber temperature.

Figure 2 shows a schematic illustration of a cooking device according to a further embodiment of the invention. This cooking device comprises a water tank 1 in a housing not illustrated, a boiler used as steam generator 2, a cooking chamber 3, a microwave generator not shown, and a control unit 4. The water tank 1 preferably is a drawer like insert having a capacity of water of preferably more than 500 ml, in a preferred embodiment more than 800 ml, and in another embodiment more than 1 litre. Water may be withdrawn from the water tank 1 by means of a sucking pipe 5 and a sucking pump 6 which water may be supplied to the steam generator 2. Water remaining in the steam generator 2 after operation may be pumped back to the water tank 1 via a drain pump 8. A heating coil 9 is arranged in the steam generator 2 and is supplied with a current by the control unit 4 if needed. Steam enters the cooking chamber 1 via a pipe 10 and heats the food when the water in the steam generator 2 boils. Excessive steam escapes via an opening 11. In case the water level in the steam generator 2 falls below a certain threshold, in normal operation the control unit 4 switches on the pump 6 such that water may be replenished by water from the water tank 1. For this purpose a level sensor is provided in the steam generator 2 (not shown). A cooking chamber temperature sensor 12 is provided for regulating a temperature Tg. Further, a temperature sensor 18 is provided for measuring the temperature Tx of steam escaping at the opening 11. It proves that the temperature Tx rises as soon as steam starts escaping through the opening 11. A steam escape may therefore be detected, for example, by comparing the temperature Tx with a first temperature threshold Tl, wherein the first threshold may show a value between 30° and 50° degrees Celsius, for example. In case of Tx > Tl steam will escape through the opening 11, i.e. a certain steam level is reached in the cooking chamber 1 where there is supposed to be sufficient steam present for conducting a microwave operation in a more energy efficient way, i.e. with less power and / or with a better cooking result than in the absence of steam.

In a second operation mode an escape of steam again is detected with the aid of the temperature sensor 18 wherein the measured temperature Tx is compared with a second threshold T2, having an exemplary value between 50° and 70° degrees Celsius. In case of Tx > T2 steam escapes through the opening 11 in an intensive way, i.e. the steaming in the cooking chamber 1 is in full swing and may even be accelerated by adding microwaves. Insofar, the microwave generator is switched on in this scenario if the second threshold T2 is exceeded, i.e. if Tx > T2.

Further, the cooking device has an input unit 13 for the user to adjust the desired target temperature Tg of the cooking chamber 3. Further, a top heater 20 and a bottom heater 21 may be arranged which may be used for heating the ceiling and the base of the cooking chamber 3 respectively. Alternatively, or in addition, heaters arranged at sides may be provided for heating the side walls. The heater 19 and optionally the top heater 20 and the bottom heater 21 may inter alia be used for preheating the cooking chamber prior to the steaming. The cooking chamber 3 is pre-heated to a pre-heating temperature Tgv before steam is supplied. Such preheating temperature may preferably be at 1 0 to 10° degrees Celsius, in particular at ca. 5° Celsius below the target temperature Tgs. Only when the pre-eating temperature Tgv is reached, steam will be supplied to the cooking device. By this measure excessive condensation or steam detonation may be avoided.

While in the present application preferred embodiments of the invention are described it is clearly emphasized that the invention is not limited to these embodiments and may be implemented in a different manner within the scope of the subseguent claims.

Claims

A food preparation device comprising a cooking space (1,3) for receiving the food, a steam generator (2, 4) for supplying steam to the cooking space (1,3), a sensor for measuring a steam parameter coming out of the cooking space (1, 3) through an opening (11, 14), which opening (11, 14) in the cooking space (1, 3) allows steam to exit the cooking space (1, 3), or a sensor for measuring a parameter of steam in the cooking compartment (1, 3), a microwave generator (31) for heating the food in the cooking compartment (1, 3), characterized in that there is a control unit (24) for controlling the microwave generator (31) during prior application of steam to the cooking compartment (1,3) depending on the parameter measured by the sensor.

The cooking device according to claim 1, wherein the sensor is a temperature sensor (18) for measuring the temperature (Tx) of steam coming out through the opening (11, 14).

Cooking device according to claim 1 or 2, wherein the sensor is arranged in a projection of the opening (11, 14) extending outwardly.

Cooking device according to claim 1, wherein the sensor is designed as a moisture sensor for measuring the moisture in the cooking space (1,3).

Preparation device according to one of the preceding claims, wherein the control unit (24) is designed to control the microwave generator (31) depending on the over and / or below threshold value (T1, T2) of the measured parameter.

Cooking device according to one of the preceding claims, wherein the control unit (24) is designed for switching on and / or switching off the microwave generator (31) according to the measured parameter, and / or where the control unit (24) is designed to increase and / or or reduce the power of the microwave generator (31) depending on the measured parameter.

Cooking device according to one of the preceding claims, wherein the control unit (24) is designed to control the microwave generator (31) depending on the measured parameter in case the steam generator (2, 4) is activated.

Preparation device according to one of the preceding claims, with a water container (1) for receiving water for conversion to steam by means of the steam generator (2, 4), said water container (1) having a volume of more than 500 ml and wherein the water container (1) preferably has a volume of more than 800 ml.

Cooking device according to one of the preceding claims, with a selector switch for selecting one of several cooking programs, wherein the control unit (24) is designed to control the microwave generator (31) solely by the measured parameter in the case of selecting a associated cooking program using the selector switch is registered.

Process for operating a cooking device according to one of the preceding claims for cooking a food, in which steam generated by the steam generator (2, 4) is supplied to the cooking space (1, 3), where a steam parameter arriving out of the cooking space (1, 3) through the opening (11, 14), or a parameter of steam in the cooking space (1,3) is measured and where the microwave generator (31) is controlled depending on the measured parameter.

The method of claim 10, wherein the microwave generator (31) is controlled solely by the measured parameter in the event that the steam generator (2, 4) is activated.

Method according to one of the preceding claims 10 or 11, wherein the microwave generator (31) is switched on by exceeding a first threshold value (T1, T2) by the measured parameter.

A method according to any of the preceding claims 10 to 12, wherein the microwave generator (31) is switched off by exceeding a second threshold (T2) by the measured parameter.