EP1195560A1 - Method for heating a cooking chamber and oven using this method - Google Patents

Abstract

A method of heating a cooking chamber (2) comprising an electric heating element (3), comprises, in a phase of temperature rise of the cooking chamber, at least one downtime of the heating element electric (3). Use in particular to reduce the energy consumption of the cooking oven (1). <IMAGE>

Description

The present invention relates to a method of heating a cooking enclosure.

It also relates to an oven comprising an enclosure of cooking suitable for implementing the heating method in accordance with the invention.

It generally targets domestic electric ovens. Such a cooking oven conventionally comprises a cooking enclosure equipped with at least one electric heating element, generally consisting of an electric tubular resistance.

During the operation of this electric cooking oven, generally observes significant electrical consumption of the order from 1100 Wh.

The purpose of the present invention is to provide a method of heating to reduce the electrical consumption of an oven by cooking.

To this end, the heating method according to the invention includes, during a temperature rise phase of the enclosure cooking, at least one downtime of the electric heating element.

This takes advantage of the inertia of the electric heating element to continuously heat the cooking chamber, although the operation of the electric heating element is interrupted intermittently.

By thus interleaving one or more downtimes during the temperature rise in the cooking chamber, consumption is reduced of energy during this temperature rise phase.

According to a preferred characteristic of the invention, the downtime is performed when the temperature rise of the cooking chamber is substantially constant over time.

So when the temperature rise curve has a slope constant, you can safely stop the operation of the element electric heater.

The slope of the temperature rise curve is then not modified and remains substantially identical to that obtained when the element electric heater works continuously.

• soit une phase de préchauffage de l'enceinte de cuisson jusqu'à une température de consigne ;
• soit une phase de régulation adaptée à maintenir la température de l'enceinte de cuisson à une température de consigne.

In practical terms, the temperature rise phase can be:

• either a phase of preheating the cooking chamber to a set temperature;
• or a regulation phase adapted to maintain the temperature of the cooking chamber at a set temperature.

According to an advantageous characteristic of the invention, allowing to further reduce the electric consumption of the oven, the process of heating according to the invention includes several downtimes in the temperature rise phase.

According to another aspect of the invention, an oven comprising a cooking chamber equipped with at least one electric heating element, comprises cut-off means associated with the electric heating element and adapted to control stopping times of the electric heating element during a temperature rise phase of the cooking chamber.

Such a baking oven is perfectly suited to use the heating method according to the invention.

It has advantages similar to those described previously in terms of reduction in the energy consumed.

According to a preferred characteristic of this aspect of the invention, the oven includes an economical operation control button suitable for controlling the implementation of the heating process in accordance with the invention.

This command button allows you to offer the user a economical operation of the baking oven as an option.

Other features and advantages of the invention will become apparent again in the description below.

• la figure 1 est une vue schématique d'un four de cuisson conforme à l'invention ;
• la figure 2 est une courbe illustrant la montée en température et la consommation d'énergie pendant une phase de préchauffage lors de la mise en oeuvre d'un procédé de chauffage traditionnel et du procédé de chauffage conforme à l'invention ; et
• la figure 3 est une courbe illustrant la montée en température et la consommation d'énergie pendant une phase de régulation lors de la mise en oeuvre d'un procédé de chauffage traditionnel et du procédé de chauffage conforme à l'invention.

In the appended drawings, given by way of nonlimiting examples:

• Figure 1 is a schematic view of a cooking oven according to the invention;
• FIG. 2 is a curve illustrating the rise in temperature and the energy consumption during a preheating phase during the implementation of a traditional heating method and of the heating method according to the invention; and
• FIG. 3 is a curve illustrating the rise in temperature and the energy consumption during a regulation phase during the implementation of a traditional heating method and of the heating method according to the invention.

We will first describe with reference to Figure 1 a furnace cooking adapted to implement the invention.

Here, the cooking oven 1 is a domestic electric oven.

This oven 1 comprises a cooking enclosure 2 intended for receive the food to be cooked.

This cooking chamber 2 is equipped with a heating element electric 3.

This electric heating element is typically a resistance electric tubular located in the upper part of the cooking chamber 2 and adapted to heat the air of the cooking chamber 2 by infrared radiation.

Of course, the oven 1 may have several elements heating. Conventionally, a second resistance called resistance of bottom, can be placed in the lower part of the oven, under the bottom plate the cooking chamber 2.

Conventionally, this baking oven 1 has different elements controlling its operation.

In particular, an on / off button 4 makes it possible to switch on or stop the oven and possibly choose different types of cooking (pulsed cooking, grill, ...).

A second temperature adjustment button 5 allows the user to choose the set temperature Tc to which it should be heated the cooking chamber 2.

This setpoint temperature Tc can typically be understood between 50 and 250 ° C.

For the implementation of this temperature regulation at inside the cooking chamber 2, there is generally provided a temperature 6 which makes it possible to continuously measure the temperature at inside the cooking chamber 2.

A microprocessor 7 controls in a conventional manner, from the setpoint temperature Tc and the temperature value measured by the probe 6, the operation of the electric heating element 3.

In accordance with the invention, the oven also includes switching means associated with the electric heating element 3.

These cut-off means are suitable for controlling times the electric heating element 3 stops during a rising phase cooking chamber temperature 2.

These switching means can be power relays of the heating element 3 controlled by the electronic system of the oven 1.

Preferably, the baking oven 1 also includes a control button 8 which allows economical operation of this oven.

When this control button 8 is pressed, the means of cutoff described above are implemented during the heating of the cooking chamber 2, during one or more phases of rise in temperature.

This control button 8 thus makes it possible to propose in a manner optional to the user of the oven economical operation of his apparatus.

Conventionally, this oven 1 also includes a fan 9 which cools the control electronics, in particular the microprocessor 7, during operation of the cooking oven 1.

This fan 9 also makes it possible to create a slight depression at inside the cooking chamber 2 by extracting the air from this chamber.

Generally, several operating speeds of this fan 9 are pre-programmed in cooking oven 1, in combination with the type of cooking that can be chosen using the on / off button 4.

When the operation control button 8 economical is actuated, it controls, via the microprocessor 7, a decrease in the fan speed 9 compared to the pre-programmed speed in a conventional operating mode.

Thus, by reducing the amount of air extracted from the enclosure of cooking 2, the heat losses in this enclosure are also reduced cooking and therefore energy loss.

This reduction in the speed of the fan 9 also contributes the energy saving achieved during the operation of this oven.

We will now describe the heating process according to the invention implemented in this cooking oven 1.

When the user wishes to cook a food inside the cooking chamber 2, the operation of the oven comprises several phases Cooking.

A first preheating phase allows a rise in temperature of cooking chamber 2 up to a set temperature Tc, as indicated by the oven adjustment knob 5.

Then, a regulation phase is implemented in order to maintain the temperature of the cooking chamber 2 at the temperature of requested setpoint Tc.

During the regulation phase, there are several increases in temperature of the cooking chamber, performed each time the temperature inside the cooking chamber 2 becomes lower than the setpoint temperature Tc.

In practice, during these temperature rise phases, the heating element 3 is put into operation.

According to the invention, during these different phases of temperature rise, either in the preheating phase and / or in the regulation phase, the heating process includes at least one time the electric heating element 3.

Thus, the operation of this electric heating element is stopped by the oven cut-off means 1.

During the same temperature rise phase, there may have several downtimes, for example distributed periodically every three minutes.

The duration of each downtime is preferably substantially equal to thirty seconds.

We will describe more precisely this heating process implemented works in the preheating phase of the cooking chamber 2 with reference in Figure 2.

In this example, the setpoint temperature Tc is fixed at 180 ° C.

In a traditional oven operation, that is to say here when the economic operation control button 8 is not activated, a temperature rise curve is observed, illustrated in lines mixed in Figure 2, which allows a rise in temperature inside the cooking chamber, from 20 ° C to 180 ° C, in a time equal to approximately 7 minutes.

During this traditional operation, consumption of energy, illustrated by the dashed line, increases linearly with course of time to reach a value close to 350 Wh at the end of the preheating phase, lasting approximately here 7 minutes.

When the set temperature Tc is reached the the heating element 3 is stopped.

When the heating process according to the invention is carried out in use, that is to say here when the operating control button 8 economic is activated, there are several downtimes ta of the element heating 3, and here two stop times ta.

Of course, as illustrated by the consumption curve of dotted energy in FIG. 2, during these downtimes ta, the power consumption is zero.

We then observe, after 7 minutes of preheating, a power consumption of the order of 320 Wh.

The gain in terms of energy consumed during this preheating phase is therefore of the order of 30 Wh.

Thus, for a preheating phase of the same duration, of the order 11 minutes, there is an energy saving during the downtimes ta, corresponding here to 1 minute of shutdown of the heating element 3.

We observe in particular that the rise curve in temperature, illustrated in solid lines in FIG. 2, is substantially identical to that obtained during traditional heating of the cooking chamber 2.

In order to obtain a temperature rise practically identical to that of traditional heating, it is preferable that the times stop ta are performed when the temperature rise in the enclosure cooking is substantially constant over time.

For this, downtime is achieved for example at least one minute after the start of the temperature rise phase in the cooking chamber 1.

We observe in fact in Figure 2, that after one minute, the temperature rise curve substantially forms a straight line.

Here, the first stop time ta is for example achieved after two and a half minutes, while the second stop time ta is achieved five minutes after the start of the preheating phase.

Likewise, the heating method according to the invention can be implemented during a regulation phase as illustrated in the figure 3.

Here, by way of example, the set temperature Tc during this regulation phase is around 200 ° C.

The regulation phase is programmed so that if the temperature inside cooking chamber 2 is approximately 6 ° C lower at the set temperature Tc, the operation of the heating element 3 is ordered in order to obtain a further rise in temperature of the enclosure cooking 2.

In traditional oven operation, the heating element 3 operates continuously so that energy consumption, such as illustrated by the curve in dotted lines, increases constantly over time to reach after two minutes a value substantially equal to 55 Wh.

The temperature in the cooking chamber, illustrated in lines mixed, also increases up to the set point of 200 ° C, temperature at which the operation of the heating element 3 is stopped.

It is observed in FIG. 3, that despite the stopping of the heating element 3 when the set temperature Tc is reached, the temperature inside of the cooking chamber continues to progress slightly and forms a temperature peak substantially equal to 201 ° C.

On the other hand, when the heating process in accordance with the invention is implemented, one or more down times ta are observed the electric heating element 3, and here a stop time ta.

As before, this downtime is implemented when the temperature rise in the cooking chamber is appreciably constant and the temperature rise curve forms a straight line.

As illustrated by the energy consumption curve in dashed in Figure 3, the stop time ta is achieved about a minute and a half after the start of the temperature rise phase.

After two minutes, consumption is observed electric of the order of 40 Wh.

The gain in terms of energy consumed is by therefore of the order of 15 Wh.

Thus, for an identical total cooking time, the different energy savings achieved during each downtime.

Thanks to a downtime ta made judiciously at the end of the phase temperature rise, when the temperature gradient is stabilized, we limits the temperature peak observed in traditional heating when the set temperature Tc is reached.

This takes advantage of the inertia of the heating element 3 to reach the value of the set temperature Tc.

The cooking oven described above thus allows to save energy when operating in an economical mode.

Here as an example, when cooking a food inside the oven, a preheating phase is implemented followed by three steps in temperature during the regulation phase. The energy gain can reach 30 Wh for preheating and 20 Wh for each rise temperature of the regulation phase, i.e. 90 Wh for the entire cooking.

Of course, many modifications can be made to the example described above without departing from the scope of the invention.

The oven may not have a control button 8 economical operation, the heating process according to the invention being implemented systematically each time the oven is used, or for certain types of cooking.

Furthermore, while previously the heating process according to the invention is implemented both during the phase of preheating and during the regulation phases, it could also not be implemented during cooking than during either of these temperature rise phases.

Finally, although the heating process applied to the upper resistance 3 of the oven 1, the same type of heating process could be implemented simultaneously or not on other elements oven heaters, and in particular to regulate the operation of the oven hearth resistance.

Claims (10)

Method for heating a cooking chamber (2) comprising at least one electric heating element (3), characterized in that it comprises, during a temperature rise phase of the cooking chamber (2), at least one downtime (ta) of the electric heating element (3). Heating method according to claim 1, characterized in that the stopping time (ta) is achieved when the rise in temperature of the cooking chamber (2) is substantially constant over time. Heating method according to one of claims 1 or 2, characterized in that the stopping time (ta) is achieved at least one minute after the start of the temperature rise phase of the cooking chamber (2 ). Heating method according to one of claims 1 to 3, characterized in that the temperature rise phase is a phase of preheating the cooking chamber (2) to a set temperature (Tc). Heating method according to one of claims 1 to 4, characterized in that the temperature rise phase is a regulation phase adapted to maintain the temperature of the cooking chamber (2) at a set temperature (Tc ). Heating method according to one of claims 1 to 5, characterized in that it comprises several stopping times (ta) in the temperature rise phase of the cooking chamber (2). Heating method according to one of claims 1 to 6, characterized in that the duration of the downtime (ta) is substantially equal to thirty seconds. Oven comprising a cooking enclosure (2) equipped with at least one electric heating element (3), characterized in that it comprises cut-off means (7) associated with the electric heating element (3) and suitable for controlling stop times (ta)) of the electric heating element (3) during a temperature rise phase of the cooking chamber (2). Oven according to claim 8, characterized in that it comprises a control button (8) for economical operation adapted to control the implementation of the heating process according to one of claims 1 to 7. Oven according to claim 9, characterized in that the control button (8) for economical operation is further adapted to control a reduction in the speed of a fan (9) of the baking oven (1).

Images