CH678996A5

CH678996A5 - Procedure and device for heating food in oven - where oven is automatically switched off shortly before completion of cooking and heat is recovered while allowing temp. to fall

Info

Publication number: CH678996A5
Application number: CH2049/89A
Authority: CH
Inventors: Edwin Keller
Original assignee: Electrolux Ag
Priority date: 1989-05-31
Filing date: 1989-05-31
Publication date: 1991-11-29

Abstract

In the heating of food in a baking oven, the required cooking temp. is pre-selected and this temp. is kept constant once the initial heating of the oven has been completed. Shortly before the expiry of the chosen cooking time, the energy supply to the oven is removed or reduced so as to enable the heat capacity of the oven to be recovered and so to save energy costs. USE/ADVANTAGE - Used for saving energy in cooking or baking. Allows part of the heat capacity of the oven to be recovered at the end of the cooking period without effecting the prod. quality, and so improves the economy of the cooking or baking operation.

Description

       

  
 



  Die vorliegende Erfindung betrifft ein Verfahren zum Wärmebehandeln von Speisen in einem Backofen sowie einen Backofen zur Ausführung des Verfahrens. 



  Bekanntlich geht beim Wärmebehandeln eines Gutes in einem Backofen die Eigenwärme des Backofens, bedingt durch dessen Masse sowie dessen spezifischen Wärmen, ungenutzt in die Umgebung. Dies entspricht der heutigen Auffassung des Energiesparens nicht. Daher bezweckt die vorliegende Erfindung, diesem Umstand Rechnung zu tragen und die Aufheizenergie des Backofens zum Teil zurückzugewinnen, um sie wenigstens teilweise dem Backgut zukommen zu lassen. 



  In diesem Sinne zeichnet sich das erfindungsgemässe Verfahren durch die Kennzeichnung gemäss Anspruch 1 aus. 



  Ein Backofen zur Ausführung des Verfahrens ist gekennzeichnet durch den Inhalt des Anspruches 5. 



  Die Erfindung wird anschliessend beispielsweise anhand einer Figur erläutert, welche ein Zeit/Temperaturdiagramm für den Betrieb des Backofens bei Verwendung einer sog. \ko- und einer Count-down-Taste darstellt. 



  Die Beeinflussung des Temperaturverlaufes im Sinne der Figur erfolgt mit Hilfe der sog. \kotaste, wel che bezweckt, die Restwärme des Backofens auszunutzen. Dabei ist schaltungsmässig vorgesehen, dass diese \kotaste nur dann ihren Einfluss ausübt, wenn der Temperaturverlauf programmiert und die sog. "Countdown-Taste", die Taste zur Begrenzung der Gutsbehandlungszeit, eingeschaltet ist. 



  Bezogen auf das Diagramm gemäss dieser Figur ist festzuhalten, dass der SOLL-Wert der Temperatur, "A", nach einer Anlaufphase zur Zeit t0 erreicht und während des Zeitintervalls t1-t0 auf diesem Wert "A" im wesentlichen konstant gehalten wird. Zur Zeit t1, welche von der programmierten Backzeit t2 abhängig ist, wird der SOLL-Wert der Temperatur auf z.B. 80 DEG C gesenkt, wobei die Temperaturanzeige bis zur Zeit t2 auf dem alten Wert "A" verbleibt. Die Behandlungszeit des Gutes beträgt t3-t0. Die Zeit t1 kann berechnet werden mittels der Beziehung t1 = t3 -  gamma  .  ln 1.176. Dabei bedeutet  gamma  die Zeitkonstante des Backofens, die experimentell zu bestimmen ist. Wenn die Temperatur den Wert  delta  = 0,85 . A zur Zeit t3 erreicht, wird das Backgut aus dem Backofen genommen. 



  Die dem Backgut total zugeführte Energie bleibt zwar gleich, aber die Heizenergie kann bereits zum Zeitpunkt t1 von entsprechend z.B. 250 DEG C auf 80 DEG C gesenkt werden und dafür die Backzeit entsprechend um t3-t2 verlängert. 



   Das Zeitintervall t0-t2, Wirkzeit des Countdowns, entspricht der effektiven Backzeit bei der Temperatur "A". Da am Ende des Backens die Temperatur von 0,85 . A genügt, um das Backwerk im gewünschten Backzustand  zu erhalten, wird durch Drücken der \kotaste eine dem Dreieck A1-B-C entsprechende Wärmeenergie gespart; diese Energie wird aber dem Backgut in der Zeit t3-t2 trotzdem vermittelt. Es ist dann das Dreieck A1-B-C inhaltlich gleich dem Dreieck A1-D-E. Letzteres gewinnt die im ersteren verlorene Energie durch Verlängerung der Backzeit um t3-t2 zurück. 



  Auf diese Weise wird die Wärmekapazität des Ofens bei geringerer Energiezufuhr ausgenützt, und der Einfluss des Abschaltens bzw. Zurückstufens auf die SOLL-Wert-Temperatur, z.B. 80 DEG C, wirkt sich auf das Backgut nicht ungünstig aus. 



  
 



  The present invention relates to a method for the heat treatment of dishes in an oven and an oven for carrying out the method.



  As is known, when a product is heat-treated in an oven, the natural heat of the oven, due to its mass and its specific heat, goes unused into the environment. This does not correspond to the current view of energy saving. Therefore, the present invention aims to take this fact into account and to partially recover the heating energy of the oven in order to at least partially transmit it to the baked goods.



  In this sense, the method according to the invention is characterized by the labeling according to claim 1.



  An oven for carrying out the method is characterized by the content of claim 5.



  The invention is subsequently explained, for example, with reference to a figure, which represents a time / temperature diagram for the operation of the oven when using a so-called \ ko and a countdown button.



  The temperature curve in the sense of the figure is influenced with the help of the so-called \ kotaste, which is intended to utilize the residual heat of the oven. In terms of circuitry, it is provided that this \ kotaste only exerts its influence if the temperature profile has been programmed and the so-called "countdown key", the key for limiting the time for handling the goods, is switched on.



  Based on the diagram according to this figure, it should be noted that the SET value of the temperature, "A", is reached after a start-up phase at time t0 and is kept essentially constant at this value "A" during the time interval t1-t0. At time t1, which depends on the programmed baking time t2, the SET value of the temperature is set to e.g. 80 ° C lowered, the temperature display remaining at the old value "A" until time t2. The treatment time of the goods is t3-t0. The time t1 can be calculated using the relationship t1 = t3 - gamma. ln 1,176. Here, gamma means the time constant of the oven, which can be determined experimentally. If the temperature is delta = 0.85. A reached at time t3, the baked goods are removed from the oven.



  The total energy supplied to the baked goods remains the same, but the heating energy can already be reduced from e.g. 250 ° C to 80 ° C and the baking time is extended accordingly by t3-t2.



   The time interval t0-t2, effective time of the countdown, corresponds to the effective baking time at temperature "A". Because at the end of baking the temperature of 0.85. A is sufficient to keep the baked goods in the desired baking state, pressing the \ kotaste saves a thermal energy corresponding to the triangle A1-B-C; however, this energy is conveyed to the baked goods in time t3-t2. The triangle A1-B-C is then the same as the triangle A1-D-E. The latter recovers the energy lost in the former by extending the baking time by t3-t2.



  In this way, the heat capacity of the furnace is used with less energy input, and the influence of switching off or downgrading on the setpoint temperature, e.g. 80 ° C, does not have an unfavorable effect on the baked goods.

Claims

1. A process for the heat treatment of food in an oven, characterized in that the selected temperature for cooking the food is selected and this treatment temperature is kept constant after the start-up phase and that the energy supply to the heating registers is interrupted or reduced even before the selected treatment time has expired to take advantage of the heat capacity of the furnace and save energy.

2nd

A method according to claim 1, characterized in that the oven is preheated to a target temperature (A), the goods are brought into the oven at the earliest when this temperature is reached, a timer element with a preselected time period t2-t0 is switched on and an organ is actuated which leads to a Time t1 with t0 <t1 <t2 lowers the oven heating in such a way that the target temperature has dropped to a predetermined value at the end of treatment t3 and part of the oven's own heat is recovered during time t3-t1.

3. The method according to claim 2, characterized in that the predetermined value is 85% of the target temperature (A).

4th

A method according to claim 3, characterized in that the switching time t1 of the setpoint reduction and the end of the baking time t3 according to the relationship t1 = t3 - gamma. Matched to each other in 1,176, where gamma is the time constant of the oven.

5. Baking oven for performing the method according to claim 1, characterized by a \ ko button which is operatively connected to a time selection button.

6. Oven for performing the method according to claim 2 or 3, characterized by a selection element for the temperature setpoint, a selection element for measuring the baking time t3-t0 and a time-controlled organ to lower the setpoint temperature at time t1 before the end of the baking time t3. 1. A process for the heat treatment of food in an oven, characterized in that the selected temperature for cooking the food is selected and this treatment temperature is kept constant after the start-up phase and that the energy supply to the heating registers is interrupted or reduced even before the selected treatment time has expired to take advantage of the heat capacity of the furnace and save energy. 2nd

A method according to claim 1, characterized in that the oven is preheated to a target temperature (A), the goods are brought into the oven at the earliest when this temperature is reached, a timer element with a preselected time period t2-t0 is switched on and an organ is actuated which leads to a Time t1 with t0 <t1 <t2 lowers the oven heating in such a way that the target temperature has dropped to a predetermined value at the end of treatment t3 and part of the oven's own heat is recovered during time t3-t1. 3. The method according to claim 2, characterized in that the predetermined value is 85% of the target temperature (A). 4th

A method according to claim 3, characterized in that the switching time t1 of the setpoint reduction and the end of the baking time t3 according to the relationship t1 = t3 - gamma. Matched to each other in 1,176, where gamma is the time constant of the oven. 5. Baking oven for performing the method according to claim 1, characterized by a \ ko button which is operatively connected to a time selection button. 6. Oven for performing the method according to claim 2 or 3, characterized by a selection element for the temperature setpoint, a selection element for measuring the baking time t3-t0 and a time-controlled organ to lower the setpoint temperature at time t1 before the end of the baking time t3.