EP1936279A1 - Method and device for evaluating the amount of vapour over time emitted by the food during cooking in an oven cavity - Google Patents

Abstract

The method involves extending a measuring head (14) into a cooking chamber (2) or into an expelled moisture channel (6) for heat dissipation into a cooling body (18), and protecting the head from condensation on a measuring head surface by spatial arrangement and/or operation mode of an oven. The temporal distribution of temperature at the head and the temporal distribution of temperature to a cooking chamber atmosphere are measured using respective temperature sensors (24, 26). The temporal distribution of steam quantity is determined based on measurement signals in an evaluation circuit. An independent claim is also included for a device for execution of a method of determining temporal distribution of steam quantity.

Description

The invention relates to a method for determining the time course of the votes during a cooking process in a cooking chamber of a baking oven of a food to be cooked amount of steam.

It is generally known that the change in the amount of steam delivered by a cooking product during a cooking process in a cooking chamber of a baking oven during a time interval directly, for example via a humidity sensor according to the US 4,734,554 , or indirectly, for example via an oxygen sensor to detect to allow a moisture-dependent control of the oven, for example, to automatically determine the end of cooking time. For Garraumbeheizung all known to those skilled and suitable heat sources can be used here, with the exception of heating steam, since a distinction between the water vapor, which is released from the food during cooking and the heating steam is not possible. However, the described sensors are relatively expensive.

From the DE 44 01 642 A1 In addition, a device for steam cooking is known in which the amount of steam is regulated by the heating of the cooking chamber. The amount of steam present in the cooking chamber is determined by a temperature sensor. The temperature sensor has a measuring part, which is located in a condensation section, and a fastening part, which is in contact with the ambient air. As a result, a temperature is set at the temperature sensor which is below the steam temperature.

Furthermore, the sees DE 41 09 565 A1 a method in which a so-called condensate trap is used to detect the vapor content in a cooking chamber. The temperature profile on the condensate trap during condensation is monitored and used for the automatic determination of the vapor content. This method is therefore designed for cooking appliances in which steam is used as a heating medium. A distinction between the steam that is released from the food during cooking and the heating steam is not required, since only the supply of heating steam to be regulated here.

The invention thus provides the problem of specifying a method in which the time course of the output during a cooking process in a cooking chamber of a baking oven of a food to be cooked steam quantity can be determined automatically with low-cost means.

According to the invention, this problem is solved by a method having the features of patent claim 1. Advantageous embodiments and further developments of the invention will become apparent from the following subclaims.

The achievable with the present invention consist in particular in the automatic determination of the time course of the votes during a cooking process in a cooking chamber of a baking oven of a food to be cooked with low-cost means.

An advantageous development of the teaching according to the invention provides that, in addition, the temperature of the heat sink is measured by a third temperature sensor and the time profile of the amount of steam during the cooking process is determined in dependence on the forwarded by the three temperature sensors to the control signals. As a result, the accuracy of the method is improved.

An advantageous development of the aforementioned embodiment provides that the temperature in the interior of the heat conduction body, between the measuring head and the heat sink, by a fourth temperature sensor is measured and depending on the forwarded by the four temperature sensors to the control signals the time course of the amount of steam during of the cooking process is determined. In this way, the accuracy of the method is further improved, so that in addition, the absolute value of the water vapor output from the food can be determined at a time during the cooking process.

Basically, the further processing of the inventively determined time course of the amount of steam in the oven according to their nature within wide suitable limits selectable. An advantageous further development provides that the cooking state of a cooking product cooking in the cooking chamber is automatically determined as a function of the time profile of the steam quantity in the cooking chamber.

An advantageous development of the aforementioned embodiment provides that with an increase in the amount of steam during an initial phase of a cooking process and a decrease in the amount of steam during an on the initial phase temporally following final phase of the cooking process, the end of the cooking process is automatically determined. As a result, the user is provided a very valuable information about the cooking process in a particularly simple manner.

Another problem is to provide an apparatus for performing a method according to any one of claims 1 to 5 available.

According to the invention, this problem is solved by a device having the features of patent claim 6. Advantageous embodiments and further developments of the invention will become apparent from the following subclaims.

Characterized in that the heat-conducting body of the device according to the invention comprises a measuring head, the relative to a main extension direction of the Wärmeleitkörpers relative to The measuring head recessed connecting part is thermally conductively connected to the heat sink, a particularly compact design is possible.

An advantageous development provides that the heat-conducting body is designed as a solid aluminum body. In this way, a particularly good heat conduction is realized, so that the heat-conducting body can be made even more compact.

Another advantageous embodiment provides that the heat-conducting body and the heat sink are formed as a single solid body. As a result, the design effort is reduced.

A further advantageous embodiment provides that the heat-conducting body is thermally decoupled from the body of the oven by means of insulation, wherein the insulation is arranged in the region between the measuring head and the heat sink at the connecting part. In this way, a particularly simple and inexpensive thermal insulation is realized.

Figur

eine erfindungsgemäße Vorrichtung zur Durchführung des erfindungsgemäßen Verfahrens.

An embodiment of the invention is shown purely schematically in the drawing and will be described in more detail below. It shows the

figure

a device according to the invention for carrying out the method according to the invention.

In the single FIGURE, a device according to the invention is shown roughly schematically. This is an oven with a closable by a door cooking chamber 2, in which a food 4 is prepared. During the cooking process resulting vapors is discharged via a connected to the cooking chamber 2 by means of an opening 5 flow-connected vapor channel 6 to the free environment, which is symbolized by arrows 8. The vapor consists of air and during the cooking process from the food 4 escaping water vapor, which is indicated by a cloud 10.

A heat-conducting body 12 with a measuring head 14 protrudes into the vapor channel 6 from the outside. The heat-conducting body 12 is connected in a heat-conducting manner to a heat sink 18 via a connecting part 16, which projects back with respect to the measuring head 14. In the present embodiment, the measuring head 14 and the connecting part 16 of the heat conducting body 12 are formed with the heat sink 18 as a single solid body. For better heat conduction of the aforementioned body, so the heat-conducting body 12 and the heat sink 18 is formed as an aluminum part. In principle, however, other materials known and suitable to the person skilled in the art are also conceivable. For better cooling, the heat sink 18 is arranged in the cooling air flow of a blower, not shown, and additionally has Cooling fins 18.1 on. The cooling air flow is symbolized by an arrow 20. In principle, it would also be possible that the heat sink is not cooled by a forced flow, but by free convection.

In order to prevent the unwanted condensation of the water vapor contained in the vapor at the measuring head 14, it is sufficient in the present exemplary embodiment that the heat-conducting body 12 is arranged in the vapor channel 6. By the prevailing during the cooking process in the vapor channel 6 flow conditions and given in normal operation of the oven further operating conditions, such as the usual cooking space temperatures, the cooling capacity of the heat sink 18 and the fact that no heating steam is used to heat the cooking chamber 2, is guaranteed in that no condensation takes place on the measuring head 14 during the cooking process. The exhaust air flow is generated for example by a suction fan 21. The exhaust fan 21 is designed here and its operation is adapted to the individual oven so that the flow conditions in the vapor channel 6 are substantially constant. For the method according to the invention and the device for carrying it out, it is absolutely necessary that no condensation takes place at the measuring head.

In addition to the aforementioned possibility, it would also be possible to place the measuring head 14 directly in the cooking chamber 2, provided that the above condition, namely the avoidance of condensation on the measuring head 14, is guaranteed for all possible operating states of the oven during a cooking process.

In order to avoid unwanted heat dissipation from the heat-conducting body 12 in the cooking chamber 2.1 and thus in the body of the oven, a thermal insulation 22 is provided. Due to the relative to the measuring head 14 and the heat sink 18 recessed connecting part 16, the holder of the insulation 22 on the heat conducting body 12 in a particularly simple manner possible. For example, it is conceivable that the insulation 22 has a through hole 22.1 corresponding to the connecting part 16 and is slotted on one side, so that the insulation 22 can be slipped onto the heat conducting body 12 by means of the slitting without additional tools and without additional fastening means.

Furthermore, the unit formed of heat conducting body 12 and heat sink 18 by means of the heat sink 18 via conventional fasteners on the body of the oven be held. Thus, the heat conduction is further reduced by the heat-conducting body 12 in the cooking chamber 2.1 and thus in the body of the oven.

For measuring the temperature at the measuring head 14, a first temperature sensor 24 on the measuring head 14 and for measuring the temperature of the cooking chamber, a second temperature sensor 26 is disposed on the vapor channel 6. The second temperature sensor 26 is here arranged on the measuring head 14 opposite wall of the vapor channel 6. It is important that the two Tempratursensoren 24 and 26 and thus the measuring head 14 and the second temperature sensor 26 are arranged as close to each other to exclude interference, for example, by increasing cooling of the Wrasens in the flow through the Wrasenkanals 6. The electrically conductive connection of the two temperature sensors 24, 26 to a control of the oven is not shown in detail. For example, it would be possible to guide the electrical leads of the first temperature sensor 24 through the insulation 22.

The method according to the invention is explained in more detail below with reference to FIG.

The inventive method is based on the heat conduction from the measuring head 14 via the connecting part 16 to the heat sink 18. For this it is necessary that the temperature in the cooking chamber 2 and thus in the vapor channel 6 is greater than the temperature of the heat sink 18.

$${\mathrm{\alpha }}_{\mathrm{Wrasen}}\mathrm{\times }{\mathrm{A}}_{\mathrm{Messkopf}}\mathrm{\times }\left({\mathrm{T}}_{\mathrm{Wrasen}}\mathrm{-}{\mathrm{T}}_{\mathrm{Messkopf}}\right)\mathrm{=}\mathrm{\lambda }\mathrm{\times }\left(\mathrm{1}\mathrm{/}\mathrm{L}\right)\mathrm{\times }{\mathrm{A}}_{\mathrm{verbindungsteil}}\mathrm{\times }\left({\mathrm{T}}_{\mathrm{1}}\mathrm{-}{\mathrm{T}}_{\mathrm{2}}\right)$$

wobei Q= Wärmestrom, α_Wrasen= Wärmeübergangskoeffizient, A= jeweilige Durchtrittsfläche für den Wärmestrom, L= Länge und λ= Wärmeleitfähigkeit des Verbindungsteils 16 sowie T= jeweilige Temperatur, mit T₁ der Temperatur des Verbindungsteils 16 an dem dem Messkopf 14 zugewandten Ende und T₂ der Temperatur des Verbindungsteils 16 an dem dem Kühlkörper 18 zugewandten Ende entspricht.The heat of Wrasens is entered via the measuring head 14 in the heat-conducting body 12. Since the heat input from the vapor into the heat-conducting body 12 is dependent on the surface of the measuring head 14, the measuring head 14 is therefore advantageously designed widened with respect to the connecting part 16. Due to the insulation 22, the following equations for heat dissipation through the heat-conducting body 12 can now be set up: $${\mathrm{Q}}_{\mathrm{vapors}/\mathrm{probe}}={\mathrm{Q}}_{\mathrm{connecting\; part}}$$

$${\mathrm{\alpha }}_{\mathrm{vapors}}\mathrm{\times }{\mathrm{A}}_{\mathrm{probe}}\mathrm{\times }\left({\mathrm{T}}_{\mathrm{vapors}}\mathrm{-}{\mathrm{T}}_{\mathrm{probe}}\right)\mathrm{=}\mathrm{\lambda }\mathrm{\times }\left(\mathrm{1}\mathrm{/}\mathrm{L}\right)\mathrm{\times }{\mathrm{A}}_{\mathrm{connecting\; part}}\mathrm{\times }\left({\mathrm{T}}_{\mathrm{1}}\mathrm{-}{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="imgf0001.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{2}}\right)$$

where Q = heat flow, α _vapors = heat transfer coefficient, A = respective passage area for the heat flow, L = length and λ = thermal conductivity of the connecting part 16 and T = respective temperature, with T ₁ the temperature of the connecting part 16 at the end facing the measuring head 14 and T ₂ corresponds to the temperature of the connecting part 16 at the heat sink 18 facing the end.

Since the aim of the method according to the invention is not the determination of the absolute value for the amount of steam escaping from the food to be cooked during a cooking process, but only the time course, ie the change in the amount of steam escaping from the food during a cooking process in a time interval, it is for the invention Method sufficient to determine the temperature difference (T _Wrasen - T _{measuring head} ) between the first and the second temperature sensor 24 and 26. From this temperature difference (T _Wrasen - T _{measuring head} ) can then in the control of the oven according to equation (2) close to α _vapors and thus on the time course of the votes during the cooking of the food 4 steam amount, as α _vapors of the in The amount of steam contained in the vapor depends.

For this purpose, the temperature at the measuring head 14 of the Wärmeleitkörpers 12 by means of the first temperature sensor 24 and the temperature of the cooking chamber atmosphere by means of the second temperature sensor 26 continuously or at predetermined time intervals during the entire cooking process is measured. From the measured values, as already explained above, the temperature difference (T _Wrasen -T _{measuring head} ) is formed in the evaluation circuit of the control, from which it is then possible to deduce the quantity of steam emitted by the food 4. From the measured values determined in the course of the cooking process, ie the temporal courses of the measured temperatures, and the temperature differences formed therefrom, ie the time profile of the temperature difference, the time profile of the amount of steam discharged from the cooking product 4 during cooking in the cooking chamber 2 thus results ,

Since here only the determination of the time course of the votes of the food 4 during a cooking process amount of steam and not the absolute amount of steam interested, it would also be possible in principle to dispense with the above-mentioned insulation 22.

As already explained, the additional measurement of the temperature at the measuring head 14 facing the end of the connecting part 16 by a third temperature sensor 28 and the measurement of the temperature at the heat sink 18 facing the end of the connecting part 16 by a fourth temperature sensor 30 of improving the accuracy of process. Furthermore, this opens up the additional possibility of automatically determining the absolute value of the steam delivered by the food 4 in the control.

In the present exemplary embodiment, depending on the temperatures measured by the first and second temperature sensors 24, 26, the cooking state of the cooking product 4 is automatically determined. In particular, this extrapolates when the cooking process will be completed. The thus estimated cooking time is displayed in a manner known to those skilled in the art, for example on a display of the oven, not shown and updated continuously or at predetermined intervals. For this purpose, it is monitored by means of the aforementioned temperature measurements, whether the amount of steam decreases again after an increase during an initial phase of the cooking process during a subsequent subsequent final phase of the cooking process.

The invention is not limited to the present embodiment. For example, other materials known and suitable to the person skilled in the art can also be used for the device according to the invention. Other structural embodiments of the device are possible. In addition to the use of the determined in the aforementioned manner over time of the votes from the food during a cooking process amount of steam for automatic determination of the cooking time, other known uses are possible.

Claims (9)

Method for determining the time course of the amount of steam delivered by a cooking product (4) in a cooking chamber (2) of a baking oven, wherein a measuring head is provided in the cooking chamber (2) or in a steam channel (6) connected to the cooking chamber (2) (14) of a Wärmeleitkörpers (12) for heat dissipation to a outside of cooking chamber (2) and vapor channel (6) arranged heat sink (18) protrudes and wherein the measuring head (14) by its spatial arrangement and / or the operation of the oven before the precipitation is protected by condensate on the measuring head surface and the time course of the temperature at the measuring head (14) of the Wärmeleitkörpers (12) by means of a first temperature sensor (24) and the time course of the temperature of the cooking chamber atmosphere by means of a second temperature sensor (26) is measured and in Dependence of the measurement signals generated by the two temperature sensors (24, 26) in an evaluation circuit of a control the time course of the steam quantity is determined. Method according to claim 1,
characterized,
that in addition the temperature of the heat sink (18) by a third temperature sensor (30) is measured and determined in dependence of the of the three temperature sensors (24, 26, 30) forwarded to the control signals the time course of the amount of steam during the cooking process. Method according to claim 2,
characterized,
in that the temperature in the interior of the heat conducting body (12), between the measuring head (14) and the cooling body (18), is measured by a fourth temperature sensor (28) and in dependence on the temperature of the four temperature sensors (24, 26, 28, 30 ) to the controller forwarded measuring signals, the time course of the amount of steam during the cooking process is determined. Method for controlling a cooking process comprising a method according to one of claims 1 to 3,
characterized,
in that the cooking state of a cooking product (4) cooking in the cooking chamber (2) is automatically determined as a function of the time profile of the amount of steam in the cooking chamber. Method according to claim 4,
characterized,
that when the amount of steam increases during an initial phase of a cooking process and a decrease in the amount of steam during an end phase of the cooking process that follows the initial phase, the end of the cooking process is automatically determined. Apparatus for carrying out one of the methods according to claims 1 to 5, comprising a heat-conducting body (12) for dissipating heat from a cooking chamber (2) or a vapor channel (6) of a baking oven to a cooling body arranged outside of cooking chamber (2) and vapor channel (6) (18), wherein the heat conducting body (12) with a measuring head (14) in the cooking chamber (2) or the Wrasenkanal (6) protrudes and at the measuring head (14) a first temperature sensor (24) and in the cooking chamber (2) or the vapor channel (6) a second temperature sensor (26) is arranged,
characterized,
that the measuring head (14) via a transversely to the main direction of extension of the heat conducting (12) relative to the measuring head (14) recessed connecting portion (16) with the cooling body (18) is heat-conductively connected. Device according to claim 6,
characterized,
that the heat-conducting body (12) is formed as a solid aluminum body. Apparatus according to claim 6 or 7,
characterized,
that the heat-conducting body (12) and the heat sink (18) are formed as a single solid body. Device according to one of claims 6 to 8,
characterized,
that the heat-conducting body (12) by an insulation (22) of the body (2.1) of the oven is thermally decoupled, wherein the insulation (22) in the region between the measuring head (14) and the heat sink (18) on the connecting part (16 ) is arranged.

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