EP2461107A1 - Cooking device and method for operating same - Google Patents

Abstract

The method involves comparing a required time for evaporating a preset quantity of fluid i.e. water, with a time value characterized for the quantity. A correction value is determined from the comparison. A correction factor is derived from the correction value. The fluid to be evaporated is supplied to a heating device from a storage container. A temperature curve over time and a characteristic evaporation temperature is determined. A measure of calcification of an evaporating device is derived by changing the evaporation temperature. An independent claim is also included for a cooking device comprising an evaporating device for evaporating a cooking chamber.

Description

The present invention relates to a cooking appliance and a method for steaming the cooking chamber of a cooking appliance.

Modern cooking appliances make cooking and baking considerably easier and, thanks to various additional functions, offer the possibility of qualitatively improving the result of a cooking process. In the field of cooking appliances with a cooking chamber, such as an oven, such an advantageous function may be the steaming of the cooking chamber. In this case, steam is introduced into the cooking chamber, whereby the humidity of the cooking process can be adjusted to the appropriate preferred conditions.

This is advantageous, for example, in long cooking processes of large pieces of meat, which can dry out more easily without suitable steaming. In particular, even when baking bread or rolls the steaming of the cooking chamber is advantageous. At the beginning, steaming may be beneficial in walking the dough to keep the surface of the dough pieces smooth so that they do not crack. At certain times, for example, at the end of the baking process, however, steaming the rolls may also have an adverse effect on the result. Therefore, a timed steaming of the cooking chamber is useful to adjust the introduction of steam into the oven to the various needs of the cooking process.

The radiators used for evaporation are tested for the evaporation times of certain amounts of liquid at a constant 230 volts. Depending on the location of a cooking appliance, however, different voltages may later be available, as a result of which the steaming conditions may under certain circumstances vary considerably. For example, in rural areas, only lower voltage can be available. This can lead to deviations from the desired evaporation conditions. Although this could be determined and compensated by an additional built-in voltage sensor, but the additional technology to be installed is relatively expensive.

Furthermore, even with the use of a voltage sensor, constant conditions would not necessarily be guaranteed. Other necessary components, such as a pump for sucking water and the radiator itself, usually have certain tolerances that can lead to a different result. Even the air pressure can when using a cooking appliance in very high altitude regions, such as in the Bergen, to be regarded as a disruptive factor. A correction of all deviations is technically complex.

It is therefore the object of the present invention to provide a cooking appliance, in which the desired conditions during cooking are easily maintained better.

This object is achieved by a method for operating a cooking appliance having the features of claim 1 and by a cooking appliance for carrying out such a method having the features of claim 13. Preferred developments of the invention emerge from the subclaims. Further advantages and features of the invention are specified in the embodiment.

The inventive method is suitable for steaming at least one cooking chamber of a cooking appliance. There is provided an evaporation device comprising a heater and at least one supply for liquids and at least one discharge for steam. The at least one discharge is suitable and designed to at least partially lead the generated steam into the cooking chamber. In this case, the time required to evaporate a certain amount of liquid is compared with a characteristic of this amount time value. From this at least one correction value is then determined.

Such a method offers many advantages. A considerable advantage is that the time required for the current process, ie the actual value, for the evaporation of a specific amount of liquid is compared with a time value characteristic of the quantity, that is to say the desired value. By comparing the actual and setpoint, it is possible to check whether the steaming of the cooking chamber has been carried out correctly.

The determined correction value makes it possible to better adjust the cooking appliance to the desired conditions. Many applications may require a certain amount of steam or a precise evaporation time. In order to ensure this, the method according to the invention can be advantageously used for an optimum result.

In preferred embodiments, a correction factor is derived from the correction value. For this purpose, for example, a characteristic value determined mathematically or empirically, in particular from the currently existing conditions, could be used to derive a correction factor in conjunction with the correction value. In the simplest case, the determined correction value could be set in relation to the characteristic time value in such a way that a correction factor in percent is obtained. The percentage representation of the difference between the actual and the setpoint makes it easier to adjust the conditions for the next cooking process. Of course, other transformations of the correction value in a correction factor are conceivable and possible.

In the characteristic value also further conditions can be considered. It may also be useful, for example, to include further current conditions in the characteristic value, such as the temperature, the cooking method or possibly also the food to be cooked. The characteristic value can also be used to take into account a determined difference between setpoint and actual value only proportionally for the next cooking process.

Preferably, the liquid to be evaporated is supplied to the heating device from a storage container. This allows a user to provide the desired amount of liquid prior to the cooking process of the evaporator. It is also conceivable, however, that the reservoir is replaced by a fresh water connection. For controlled evaporation of a certain amount of liquid can then z. B. may be provided a flow meter. This is particularly useful when the method is used in a continuous cooking process. For example, this also makes possible the use of the method for cooking or baking lines. The evaporation would be determined via the flow meter a certain flow rate per time. This could then be derived again a correction value.

Preferably, a temperature profile is determined over time. This may refer to the heater, the reservoir or even the whole evaporation device. Of course, measuring the temperature in other places is also conceivable. Furthermore, it is preferred that a characteristic evaporation temperature is determined.

Particularly preferably, the determined temperature profile is stored. By varying the characteristic evaporation temperature, a measure of the calcification in the evaporation device can be derived.

The characteristic evaporation temperature corresponds to the height of the plateau of the temperature profile, which quickly sets after the beginning of the evaporation. By storing the temperature profiles in a dedicated memory device, the temperature profiles of different evaporations can be compared. With increasing calcification of the evaporation device, in particular the heater, the height of this temperature plateau changes. By comparing the temperature plateaus of different evaporation processes can be assessed how much the evaporation device is calcified.

Whether or when the evaporation device must be decalcified can be evaluated via the plateau development and subsequently controlled. However, it is also conceivable that the descaling of the evaporation device is not determined by comparing different evaporation processes. For example, the evaporator would then descale when the plateau exceeds a predetermined temperature.

Normally, the temperature of the plateau increases continuously slowly during the evaporation processes. However, if the temperature drops, this could be due to measured value fluctuations or it could be that adhering lime has detached from the heating device.

The temperature remains at the characteristic vaporization temperature during evaporation until all available water has been evaporated. Depending on the design of the evaporation device, it is possible that a certain amount of liquid can not be evaporated. As soon as water is no longer available, the temperature rises abruptly. Therefore, it is preferable that the heater is turned off when the temperature further rises after reaching the characteristic evaporating temperature. It is advantageous not to choose too narrow limits. A possible value for turning off the heater would be, for example, 10 ° C, 20 ° C, 30 ° C, 40 ° C or 50 ° C above the characteristic vaporization temperature. Of course, other values are possible. In particular, it is advantageous to select the temperature for switching off the heating device so that the signal for switching off is not already reached by the calcification of the evaporation device.

In other preferred embodiments, the heating device is switched off via a threshold value sensor. In this variant too, a temperature above the characteristic evaporation temperature is selected for switching off the heating device. Here, the value for switching off the heating device can advantageously be far above the characteristic evaporation temperature. If the heater is switched off via a threshold sensor, it is not absolutely necessary to determine the temperature profile over time and to save it.

In advantageous embodiments, the amount of liquid to be evaporated is adjusted via the determined correction value, in particular via the derived correction factor. As a result, exact steam intervals can be set using the method according to the invention. In fact, for many applications it is advantageous not to achieve an exact vapor volume but an exact vapor time.

However, it is also possible to adjust the power of the heating device via the determined correction value, in particular the derived correction factor. In this context, z. B. via a transformer, the power of the heater, for example, in a certain Watt range can be varied.

Preferably, via the determined correction value, in particular via the derived correction factor, the timing of the heater can be adjusted to optimally adjust the evaporation device. In this case, the evaporation device can be gradually adjusted ideally to the evaporation of a defined amount of water in a defined time.

In all embodiments, it is preferred that the adaptation be made stepwise. The adjustment z. B. by 2%, 3%, 5%, 10% or 20% of the actual value or possibly by 10%, 20%, 30%, 40% or 50% of the determined correction factor. Absolute values in seconds or minutes, such as 30 seconds or 2 minutes, are also possible. Other values for achieving optimal conditions are conceivable and useful.

However, a gradual adaptation of the system is advantageous in order not to overly evaluate possible malfunctions. If, for example, accidentally instead of vaporizing 100 ml of water, no water of the evaporation device provided, an extremely high correction factor would be determined. Including this value in the next evaporation process would again lead to false conditions.

It is preferably possible to derive a measure of the location-dependent applied voltage via the correction factor. In particular, if components were installed with very low tolerances for the evaporation device, you can about the correction factor z. B. determine the applied voltage. The set point for the evaporation of a certain amount of water is tested in the laboratory at a constant 230 volts. With otherwise constant conditions, a measure of the locally dependent voltage can then be determined via the correction factor.

The cooking appliance according to the invention has an evaporation device for evaporating at least one cooking chamber. The evaporation device comprises at least one heating device and at least one supply for liquids. At least one discharge for steam is provided. This is suitable and designed to lead the steam at least partially into the cooking chamber. Furthermore, the cooking appliance is equipped with a control device. With this control device, the time required to evaporate a certain amount of liquid can be compared with a characteristic of this amount time value. From this, at least one correction value can be derived.

A significant advantage of such a cooking appliance is that the evaporation process can be adjusted gradually optimally to the existing conditions. In addition to a positive effect on the cooking result, it is possible to obstruct components with larger tolerances, since the cooking appliance can compensate for these tolerances using the method described above.

Preferably, the heater is associated with a reservoir. However, the storage container can also be replaced by a fixed water connection which, in conjunction with a flow meter, provides the intended amount of water to the evaporation device.

In preferred embodiments, the heating device is assigned at least one temperature and / or at least one threshold value sensor. By means of one or both sensors, it is possible to turn off the heater after evaporation of the entire water.

Further advantages and features of the present invention will become apparent from the embodiment, which will be explained below with reference to the accompanying figures.

Figur 1

eine schematische perspektivische Ansicht eines erfindungsgemäßen Gargerätes, das als Backofen ausgeführt ist;

Figur 2

eine schematische Darstellung eines Ausführungsbeispiels einer erfindungsgemäßen Verdampfungseinrichtung;

Figur 3

ein weiteres schematisch dargestelltes Ausführungsbeispiel einer erfindungsgemäßen Verdampfungseinrichtung;

Figur 4

den möglichen Temperaturverlauf von 3 Verdampfungsprozessen;

Figur 5

eine graphische Darstellung der Ermittlung eines Korrekturwertes; und

Figur 6

eine graphische Darstellung einer Umwandlung des Korrekturwertes in einen Korrekturfaktor

Showing:

FIG. 1

a schematic perspective view of a cooking appliance according to the invention, which is designed as a baking oven;

FIG. 2

a schematic representation of an embodiment of an evaporation device according to the invention;

FIG. 3

a further schematically illustrated embodiment of an evaporation device according to the invention;

FIG. 4

the possible temperature profile of 3 evaporation processes;

FIG. 5

a graphical representation of the determination of a correction value; and

FIG. 6

a graphical representation of a conversion of the correction value into a correction factor

FIG. 1 shows an inventive cooking appliance 1 that is designed here as a baking oven 21. The oven 21 has a closable with a door 22 cooking chamber 2, can be prepared in the food using different operating profiles. Among other things, via a control panel 23 between hot air operation, top and bottom heat and a grill function to get voted. The temperature can also be adjusted. The control panel 23 may be designed as a touch panel or include controls not shown in detail.

Under certain conditions, it is advantageous for the result of a cooking process to steam the cooking chamber 2 during the cooking process. This can better prevent the drying out of food. In particular, when baking bread or buns, the steaming can lead to a better result during the walking time of the dough. Vaporizing causes the surface of the dough pieces not to dry out so quickly and thus does not burst when rising.

To steam the cooking chamber 2 of the oven 21, on the rear wall of the housing 24 is an in FIG. 1 not visible inventive evaporation device 3 is arranged. An embodiment of such an evaporation device 3 according to the invention is shown in FIG FIG. 2 shown. Via a supply 5 liquids can be filled in the evaporation device 3. In the example shown here, the evaporation device 3 also comprises a reservoir 14, into which the desired amount of liquid can be filled before the start of the cooking process. Such a reservoir 14 may also be replaced by a fixed water connection. In conjunction with a flow meter then the required amount of liquid of the evaporation device 3 is provided.

Via a connecting piece 25 of the reservoir 14 is connected to the heater 4 in connection. The temperature of the heater 4 is controlled in the embodiment shown here via a sensor which may be formed as a temperature sensor 19 or threshold 17. The sensor 17, 19 may be connected via a line 28 to a control device 18, not shown here.

The resulting from the evaporation of the heater 4 steam 7 passes through a mist eliminator 26 to a discharge 6. This is suitable and designed to initiate the steam 7 in the cooking chamber 2. This can be done for example via a hose. But there are also other possibilities conceivable and useful. A direct connection of the discharge 6 with the cooking chamber 2 is appropriate.

In FIG. 3 a further embodiment of an evaporation device 3 according to the invention is shown schematically. In the example shown here, the quantity 9 of the liquid 10 intended for the corresponding cooking process is filled via the feed 5 into the storage container 14 of the evaporation device 3 with a pump 27 shown only schematically here. The water is heated by means of the heater 4 and the resulting steam 7 passes through the discharge 6 in the cooking chamber 2. Again, various connection possibilities of the discharge 6 with the cooking chamber 2 are conceivable and possible.

The heater 4, a temperature sensor 19 and a threshold value 17 are assigned in the embodiment shown. Both sensors 17, 19 are connected to a control device 18 in connection. By means of the temperature sensor 19, the temperature profile 15 of the evaporation process can be determined. The determined temperature profiles 15 can be stored in a memory device 30 provided for this purpose. The memory device 30 is connected directly to the control device 18 in the exemplary embodiment shown here. About the threshold sensor 17, which also serves as a safety switch in this case, the heater 4 is turned off when a critical temperature value is exceeded.

The control device 18 can be in operative connection via different lines 28 with different components of the oven 21 or the evaporation device 3. This is only hinted at here.

The control device 18 can furthermore compare the required time 8 for the evaporation of a specific quantity of liquid 9, 10 with a time value 11 characteristic of this quantity and determine a correction value 12 therefrom. From the determined correction value 12, a correction factor 13 can be derived either directly or in conjunction with a characteristic value. For example, in the simplest case, a useful characteristic value is the characteristic time value 11, which is set in relation to the correction value 12. The correction factor can also be derived mathematically or empirically from a variety of current conditions. The derivation of a correction factor 13 will be described by way of example in the following figures.

FIG. 4 shows several possible temperature curves 15 of a heater 4, which were determined during various evaporation processes. The temperature first rises steadily and then remains until the total available water has evaporated, constant at a characteristic evaporation temperature 16. This creates between the times t ₁ and t _2, a temperature plateau 20th

If the temperature from the plateau 20 continues to rise above the characteristic evaporation temperature 16, this is an indication that all the available water has been evaporated. The radiator 4 is then warmer with constant power, since no more heat energy can be delivered. It should be noted that, depending on the design of the evaporation device 3 not all the water, but only the entire available water can be evaporated. In the in FIG. 2 shown embodiment remain due to design about 2 ml of liquid in the connector 25 of the evaporation device. 3

An in FIG. 4 shown temperature profile 16 of the radiator 4 is measured by a temperature sensor and can be stored in the memory device 30. The control device 18 can recognize on the basis of the temperature profile 16, when all the available water has evaporated and then turn off the heater 4. If the temperature from the temperature plateau 20 further increases, for example, at a temperature 10 ° C above the temperature plateau 20 of the current evaporation, the heater 4 is turned off. Of course, the heater 4 could be switched off immediately after the rise in temperature from the temperature plateau 20. However, it is advantageous not to choose the limits too narrow, since it can also come within the plateau 20 to small variations.

However, the characteristic evaporation temperature 16 may gradually increase from evaporation to evaporation. This is illustrated by the curves with the characteristic evaporation temperatures 16.1 and 16.2. This results from the continuous calcification of the heater 4. This must spend more energy with increasing calcification in order to heat the water to be evaporated. Since the slowly forming lime layer acts as a heat barrier between the water and the heating means, the characteristic evaporation temperature 16 gradually increases gradually.

This circumstance can be exploited and derived from the comparison of several temperature profiles 15, whether the evaporation device 3 or the heating device 4 must be descaled. Such an estimate could be made by comparing a setpoint curve, which is shown here as a temperature profile 16, with the current temperature profile 15. If the temperature difference 29 of the two characteristic evaporation temperatures 16, 16.1, 16.2 exceeds a certain predetermined value, a signal for descaling could be displayed.

Alternatively, one could also choose a fixed temperature limit that the temperature plateaus 20 should not exceed during evaporation. If the characteristic evaporation temperature 16 rises above this value, a sign for descaling could accordingly be given again.

The curve of the temperature curve 15 is very characteristic. The temperature rises steadily until a time t ₁ . Between time t ₁ and t ₂ , the temperature remains approximately constant at the characteristic evaporation temperature 16. If all the water to be evaporated is consumed, the temperature rises abruptly after the plateau phase 20. This temperature profile 15, measured by a temperature sensor 19, can be determined by a control device 18. If the temperature continues to rise after reaching the temperature plateau 20, the heating device 4 is switched off.

The switching off of the heating device 4 after complete evaporation of the liquid can also be carried out without a temperature sensor 19. The heater 4 may also be associated with a threshold sensor 17, which is set at a temperature above the temperature plateau. If the temperature rises further out of the plateau 20, the threshold value sensor becomes active and the heating device 4 is switched off.

FIG. 5 shows one way in which a correction value 12 can be determined. For this purpose, the characteristic time value 11 required for evaporating a specific quantity 9 of liquid 10 is compared with the currently required time 8. The time required 8 is measured in the case shown here by hiring the radiator 4 until the temperature rises from the temperature plateau 20. As already described above, the end of the evaporation process can be determined from the change in the temperature profile 15 determined by a temperature sensor 19. Also, by a previously defined threshold, which is detected by a threshold value sensor 17, the end of the evaporation can be displayed.

In the method shown here, the correction value 12 describes the time difference between the characteristic time value 11 and the currently required time 8. For both time values, the time span from the beginning of the evaporation until reaching a particular shutdown temperature 31, 32 is taken into account. It may be useful to define the shutdown temperature 31, 32 with respect to the temperature plateau 20. For example, the controller 18 could turn off the heater 4 when the temperature rises after reaching the plateau 20 by, for example, more than 10 ° C, 20 ° C, 30 ° C, 40 ° C, or 50 ° C. Since the temperature plateaus 20 of the temperature curves 15 in the in FIG. 5 example shown have the same height, the respective shutdown temperature 30, 31 is equal. Of course, a correction value 12 can also be determined in any other conceivable and meaningful way.

From the correction value 12 and other conditions such as a characteristic value, a correction factor 13 can then be derived. Again, various methods can be used. A meaningful method in FIG. 6 is the conversion of the correction value 12 into a percentage indication. There is a graph depicting the adjustment over nine cooking cycles.

For this purpose, in the exemplary embodiment described here, the characteristic time value 11 is defined as 100%. The derived correction factor 13 is therefore equal to 10% at a characteristic time value 11 of 60 seconds and a required time 8 of 66 seconds. So it was steamed 10% too much or too long. Assuming that all changes in the conditions have a roughly linear effect on the evaporation process, the determined percentage correction factor 13 makes it easy to optimally adapt the conditions to the circumstances. However, it is within the scope of the invention, the percentage correction factor 13 to convert over appropriate Angleichfaktoren or characteristics so that even non-linear behaving changes are easily adjustable.

For example, a 10% correction factor of 13 could provide 10% less water to the evaporation process in the next process. This could quickly lead to optimal conditions. However, it may make sense to adjust the evaporation process only gradually. For example, if there is a fault or possibly no water has been supplied to the process in an evaporation, a corresponding correction factor 13 could be up to 100%. However, matching over such a value would again lead to completely wrong conditions in the next process, since twice the amount of water would be made available. Therefore, a step-by-step adjustment is advantageous.

For example, a limit could be set whereby adjustment per evaporation can be made at a maximum of 2%, 5% or 10% of the water volume. However, it is also possible to make adjustments by, for example, 10%, 20% or 30% of the correction factor 13. Of course, an adjustment in other intervals is also possible.

Of course, setting the optimum conditions for the evaporation process is not only possible via the amount of liquid to be supplied. It is also possible to vary the power of the heating device 4. Furthermore, with a timed mode of operation of the heating device 4, the timing can also be varied so that optimal conditions are gradually achieved.

The inventive method has been described in the embodiment shown here using a cooking appliance according to the invention, which is designed as a baking oven 21.

It is within the skill of one skilled in the art to modify the described embodiments in a manner not shown in order to achieve the effects described, without departing from the scope of the invention.

LIST OF REFERENCE NUMBERS

1

Cooking appliance

2

oven

3

Evaporation device

4

heater

5

supply

6

removal

7

steam

8th

needed time

9

certain amount

10

liquid

11

characteristic time value

12

correction value

13

correction factor

14

reservoir

15

temperature curve

16

characteristic evaporation temperature

16.1

characteristic evaporation temperature

16.2

characteristic evaporation temperature

17

threshold sensor

18

control device

19

temperature sensor

20

temperature plateau

21

oven

22

door

23

Control panel

24

casing

25

joint

26

Droplet

27

pump

28

management

29

temperature difference

30

memory device

31

Shutdown temperature 1

32

Shutdown temperature 2

t ₁

first time

t ₂

second time

Claims (15)

Method for steaming at least one cooking chamber (2) of a cooking device (1), wherein an evaporation device (3) is provided which has a heating device (4) and at least one supply (5) for liquids and at least one discharge (6) for steam (7 ), wherein the at least one discharge (6) is suitable and designed to lead the steam (7) at least partially into the cooking chamber (2),
characterized,
in that the time (8) required for vaporizing a specific quantity (9) of liquid (10) is compared with a time value (11) which is characteristic of this quantity, and at least one correction value (12) is determined therefrom. Method according to claim 1,
characterized,
that a correction factor (13) is derived from the correction value (12). Method according to one of the preceding claims,
characterized,
that the liquid to be evaporated to the heater (4) from a reservoir (14) is supplied. Method according to one of the preceding claims,
characterized,
that a temperature profile (15) over time and a characteristic evaporation temperature (16) is determined. Method according to claim 4,
characterized,
that the temperature profile (14) is stored and that a measure of the calcification of the evaporation device (3) is derived via a change in the characteristic evaporation temperature (16). Method according to claim 4 or 5,
characterized,
in that the heating device (4) is switched off when the temperature continues to rise after reaching the characteristic evaporation temperature (16). Method according to one of the preceding claims,
characterized,
that the heating device (4) via a threshold sensor (17) is switched off. Method according to one of the preceding claims,
characterized,
that the amount of liquid to be evaporated is adjusted via the determined correction value (12). Method according to one of the preceding claims,
characterized,
that the power of the heating device (4) is adjusted by the determined correction value (12). Method according to one of the preceding claims,
characterized,
that the timing of the heating device (4) is adjusted via the determined correction value (12). Method according to one of the preceding claims,
characterized,
in that a measure of the location-dependent voltage is derived via the correction factor (13). Method according to one of the preceding claims,
characterized,
that the adjustment is gradual. Cooking device (1) with an evaporation device (3) for steaming at least one cooking chamber (2) comprising a heating device (4) and at least one supply (5) for liquids and at least one discharge (6) for steam (7), wherein the at least one discharge (6) is suitable and designed to guide the steam (7) at least partially into the cooking space (2), and to a control device (18),
characterized,
in that the required time (8) for vaporizing a specific quantity (9) of liquid (10) is comparable with the control unit (18) with a time value (11) characteristic of this quantity and at least one correction value (12) can be derived therefrom. Cooking appliance (1) according to claim 13,
characterized,
that the heating device (4) is associated with a storage container (14). Cooking appliance (1) according to at least one of claims 13-14
characterized,
in that the heating device (4) is assigned a temperature sensor (19) and / or threshold value sensor (17).

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