EP1739359B1 - Method for temperature regulation in a domestic gas cooking appliance - Google Patents

Description

The present invention relates to a gas cooking oven, and preferably a gas domestic cooking oven.

In general, the present invention relates to the operation of a domestic gas cooking oven during a cooking program.

Traditionally, a domestic gas cooking oven comprises a muffle, one or more gas burners being adapted to heat the air contained in the muffle.

These burners are generally arranged under the bottom wall or the top wall of the muffle.

The temperature of the air contained in the muffle is generally regulated by a thermostat controlling a gas flow control valve supplying the gas burner. This valve makes it possible to increase or decrease the gas flow supplying the gas burner by constantly being lit.

These domestic gas cooking ovens make it possible to regulate the temperature of the air contained in the oven at a set temperature of between 150 and 285 ° C.

In addition, these domestic gas cooking ovens do not include a catalytic cell for the treatment of volatile organic compounds. Therefore, these volatile organic compounds are removed from the range by a natural convection duct towards the kitchen.

The documents US 3423568 and US 3480000 represent the state of the art relevant to the object of the invention.

The object of the present invention is to propose a temperature control method in a domestic gas cooking oven making it possible to release a low level of volatile organic compounds, and in particular a virtually zero carbon monoxide level during the cooking programs.

The treatment of volatile organic compounds at the moment of their release from the muffle makes it possible to eliminate the gases that are dangerous for people in the kitchen.

For this purpose, the present invention provides a temperature control method in a domestic gas cooking oven comprising a muffle whose front face is closed by a door, and comprising an upper wall, side walls, a bottom wall and a bottom wall, and at least one gas burner disposed under the bottom wall of said all-or-nothing muffle, an electric heating element fed in all or nothing disposed under the upper wall of said muffle, and said upper wall of the muffle comprising an opening adapted to receive a catalytic cell.

• une première étape de montée en température de l'air contenu dans le moufle par le fonctionnement en continu du au moins un brûleur à gaz jusqu'à une température de consigne (T) ;
• au cours de ladite première étape, l'élément chauffant électrique fonctionne pendant au moins une durée (D1) à une puissance maximum ;
• une seconde étape d'arrêt du fonctionnement du au moins un brûleur à gaz (9) pendant une durée (D2) ;
• une troisième étape de mise en fonctionnement en continu du au moins un brûleur à gaz pendant une durée (D3) ; et
• ensuite les deuxième et troisième étapes sont exécutées consécutivement pendant un cycle complet d'un programme de cuisson.

According to the invention, this method of regulating temperature in a domestic gas cooking oven comprises the following steps:

• a first step of raising the temperature of the air contained in the muffle by the continuous operation of the at least one gas burner to a set temperature (T);
• during said first step, the electric heating element operates for at least one duration (D1) at a maximum power;
• a second step of stopping the operation of the at least one gas burner (9) for a duration (D2);
• a third step of continuously operating the at least one gas burner for a duration (D3); and
• then the second and third steps are performed consecutively during a complete cycle of a cooking program.

Thus, the heating of the air contained in the muffle is regulated by putting into operation and stopping at least one gas burner and not by a change in gas flow rate supplying said at least one gas burner.

Operation at the maximum power of the electric heating element from the preheating phase of a cooking cycle activates the catalytic cell as soon as possible by achieving a rapid rise in temperature. The volatile organic compounds are removed from the first minutes of operation by this step of the temperature control process.

The catalytic cell reaches its priming temperature more quickly than the domestic gas cooking oven reaches its target temperature.

Therefore, the cracking of volatile organic compounds is maximized and these are not discharged directly outside the range. The volatile organic compounds pass through the catalytic cell.

This catalytic cell makes it possible to destroy, in particular, carbon monoxide in order to reduce the emission of toxic gas to an almost zero value.

Advantageously, the domestic gas cooking oven comprises an ignition burner adapted to ignite the at least one gas burner.

Thus, the gas burner can be ignited automatically by said ignition burner.

The rise in temperature of the air contained in the muffle extends over a wider range of temperature by adjusting the duration of ignition of the at least one gas burner.

During a cooking program in said domestic gas cooking oven, the set temperature T is between 35 and 300 ° C.

Preferably, the electric heating element is operated simultaneously with said at least one gas burner to reach a temperature of about 200 ° C to activate the catalytic cell.

The simultaneous operation of the heating element and the gas burner reduces the emission of volatile organic compounds. This principle of operation of the heating means makes it possible to suppress the emission of the compounds volatile organic substances from a temperature threshold.

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

• la figure 1 est une vue en perspective d'un appareil de cuisson domestique avec la porte dans une position ouverte conforme à l'invention ;
• la figure 2 est une vue en coupe et en élévation d'un appareil de cuisson domestique conforme à l'invention ;
• la figure 3 est un graphique illustrant l'émission de monoxyde de carbone au cours d'un programme de cuisson ; et
• la figure 4 est un graphique illustrant la montée en température du moufle et de la cellule catalytique, et les durées de fonctionnement des moyens de chauffage au cours d'un programme de cuisson.

In the accompanying drawings, given as non-limiting examples:

• the figure 1 is a perspective view of a domestic cooking appliance with the door in an open position according to the invention;
• the figure 2 is a sectional and elevational view of a domestic cooking appliance according to the invention;
• the figure 3 is a graph illustrating the emission of carbon monoxide during a cooking program; and
• the figure 4 is a graph illustrating the temperature rise of the muffle and the catalytic cell, and the operating times of the heating means during a cooking program.

We will describe first, with reference to the figure 1 , a domestic cooking appliance 1 according to the invention. This domestic cooking appliance 1 is such that a range comprising a domestic gas cooking oven.

The domestic gas cooking oven 1 can also be intended to be integrated in a built-in cabinet.

This oven 1 comprises a muffle 2 for receiving the food to be cooked. The front face 3 of the muffle 2 is closed by a door 4, and comprises an upper wall 5, side walls 6, a bottom wall 7 and a bottom wall 8.

Said oven 1 also comprises at least one heating means 9 placed under the bottom wall 8 of said muffle 2. The heating means 9 placed under the bottom wall 8 of the muffle 2, as illustrated in FIG. figure 2 , is an all-or-nothing gas burner.

In this embodiment, a single gas burner 9 has been illustrated. Of course, the muffle 2 could also include several burners 9 below the bottom wall 8 of the muffle 2.

The domestic gas cooking oven 1 may also comprise an ignition burner (not shown) adapted to ignite the at least one gas burner 9.

The muffle 2 also comprises in this embodiment an electric heating element 10 fed in all or nothing disposed under the top wall 5 of the muffle 2. This heating element 10 makes it possible to raise the temperature of the muffle more quickly in cooking mode and to activate at least one catalytic cell 16 as quickly as possible to remove the volatile organic compounds.

Of course, the assembly is described in a device housing that does not need to be described here.

In addition, all the other components necessary for the operation of a gas-fired domestic cooking appliance, such as, for example, the means for controlling and regulating the temperature, the gas supply, and the safety device are not shown or described as they may be identical to those well known to those skilled in the art.

The upper wall 5 of the muffle 2 comprises an opening 15 adapted to receive a catalytic cell 16. In this way, the combustion gases called volatile organic compounds are not discharged directly outside the domestic cooking oven gas 1. But said volatile organic compounds pass through said catalytic cell 16 coated with palladium or platinum. Such a catalytic cell 16 functions by cracking the hydrocarbons. A catalytic cell 16 may be of cylindrical or parallelepipedal shape. In the embodiment described, the catalytic cell 16 has a diameter of the order of 30 mm.

The treatment of the volatile organic compounds requires a heating means to raise the temperature of the catalytic cell 16 to eliminate said volatile organic compounds emitted in the muffle 2 of the domestic gas cooking oven 1. This heating means is the element electric heater 10 located below the upper wall 5 of the muffle 2.

The domestic gas cooking oven 1 comprises control means adapted to turn on and off the gas burner 9 and the electric heating element 10 so as to regulate the temperature of the air contained in the muffle 2 as a function of a set temperature T.

According to the process of the invention implemented, for example, during the baking step, the process starts with a first phase triggering the start of a phase of a baking cycle in the muffle 2 of the baking oven. domestic gas 1. This departure can be the start of a departure from a program selected by the user or the delayed start.

Then, a first step of raising the temperature of the air contained in the muffle 2 by the continuous operation of the at least one gas burner 9 to a set temperature T.

During said first step, the electric heating element 10 operates for at least a duration D1 at a maximum power.

The electric heating element 10 is operated sequentially during sequences of duration S1 during the first step of the process corresponding to a cooking cycle.

Said first step of operation of the at least one gas burner 9 and the electric heating element 10 corresponds to the preheating phase of the muffle 2.

Operation at maximum power of the electric heating element 10 activates the catalytic cell 16 as soon as possible.

The rise in temperature of the catalytic cell is rapid because the electric heating element 10 is close to said catalytic cell 16.

The distance between the catalytic cell 16 and the electric heating element 10 is between 30 mm and 15 mm, and preferably of the order of 20 mm.

The catalytic cell 16 is located between two branches of the electric heating element 10. The two branches of the electric heating element 10 are preferably spaced apart by a distance of the order of 55 mm.

In this way, the catalytic cell 16 can begin to process the volatile organic compounds before the domestic gas cooking oven 1 is at the set temperature T.

In addition, this temperature control method makes it possible to use a gas burner 9 from the beginning of the firing cycle while having very satisfactory results for the treatment of volatile organic compounds.

In this case, the operating sequences S1 during the operating time D1 of the electric heating element 10 are in a range extending from 5 seconds to 1 minute, and preferably of the order of 25 seconds.

The regulation of the temperature of the air contained in the muffle 2 during the first stage of the firing cycle is achieved by the operating time of the gas burner 9.

The electric heating element 10 is operated with an offset of a duration D4 with respect to the operation of the gas burner 9 during the first step of the process of a cooking cycle.

The heating element 10 is operated with a delay of a duration D4 extending in a range between 1 and 30 seconds, preferably of the order of 2 seconds.

The set temperature T is between 35 and 300 ° C during a cooking program in said domestic gas cooking oven 1.

After this first step of heating the air contained in the muffle 2, a second step of stopping the operation of the at least one gas burner 9 is performed for a duration D2.

The shutdown time D2 of the at least one gas burner 9 is in a range of 1 to 8 minutes.

The electric heating element 10 is stopped for a duration identical to the shutdown duration D2 of the at least one gas burner 9 during the second step.

Following this stop, a third stage of continuous operation of the at least one gas burner 9 is launched for a duration D3. The operating time D3 of the at least one gas burner 9 is in a range from 30 seconds to 8 minutes.

The electric heating element 10 is operated simultaneously with said at least one gas burner 9. These two heating means 9 and 10 are preferably operated simultaneously for the third stage of the process.

Then, the next step of the program is the repetition of the second and third steps performed consecutively during a complete cycle of a cooking program.

The operating time D3 of the at least one gas burner 9 is divided into sequences of duration S2. The duration of the sequence S2 extends in a range of between 20 seconds and 2 minutes, and preferably of the order of 30 seconds.

At least two sequences of duration S2 can be produced without interruption of the at least one gas burner 9, and preferably eight S2 sequences.

The electric heating element 10 operates proportionally with respect to the at least one gas burner 9 so as to respect the set temperature T. The proportional operating time of the heating element 10 with respect to the operating time D1 or D3 of the at least one gas burner 9 is managed by the control means of the domestic cooking oven 1.

The control means evaluate the temperature difference between the set temperature T and the value measured by means of a temperature probe. This measured temperature difference allows the control means to supply the electric heating element 10 for the time necessary to maintain the cooking oven 1 at the set temperature T and to avoid large fluctuations around said set temperature T.

This principle is also used during the temperature rise phase of the cooking oven 1 during the first step. A theoretical temperature rise curve of the cooking chamber is stored by the control means. This temperature rise curve is a ramp. It has the particularity to end with an asymptote to eliminate any risk of excessive temperature rise during a malfunction of the device. This learning mode of the baking oven 1 is performed in the laboratory by the Applicant.

A maximum operating time threshold of the electric heating element 10 is determined in the operating parameters of the control means. This operating time is between 15 seconds and 2 minutes and preferably from the order of 25 seconds.

Then, the control means evaluate the temperature difference between the setpoint and the measured value and adapt this operating time accordingly.

The management of said operating periods can be performed by a microprocessor having fixed durations for each cooking program or by automatic cooking means.

The electric heating element 10 operates sequentially during sequences of duration S3 during the third step of the method. The operating sequences S3 during the operating time D3 of the electric heating element 10 are in a range extending from 10 seconds to 1 minute, and preferably of the order of 25 seconds.

Furthermore, the muffle 2 comprises a temperature probe (not shown) adapted to measure the furnace center temperature. This temperature probe is connected to control means adapted to switch on and off the gas burner 9 and the electric heating element 10 so as to regulate the temperature of the air contained in the muffle 2 as a function of a heating temperature. setpoint T.

The catalytic cell 16 makes it possible to eliminate almost all the emissions of toxic volatile organic compounds from a rise in temperature of the catalytic cell of the order of 200 ° C.

This temperature control process makes it possible to respond very favorably to the normative requirements concerning emissions of carbon monoxide and carbon dioxide. This process makes it possible to treat almost all the volatile organic compounds emitted during a cooking cycle.

In this way, the temperature control method provides a product that performs well in terms of safety vis-à-vis the user since the air released into the kitchen is devoid of toxic gases.

The state of the art gas cooking apparatus did not make it possible to obtain such good performance of treatment of volatile organic compounds and to guarantee the safety of the users since said apparatus did not have a catalytic cell 16 and a temperature control method as described above.

On the figure 3 carbon monoxide emission is illustrated during a cooking program where the average temperature of the catalytic cell 16 is 190 ° C. From 16 minutes, the emission of carbon monoxide is almost zero since the maximum carbon monoxide emission value found in the tests performed by the Applicant does not exceed 0.02ppm.

Therefore, the cumulative carbon monoxide emission over a cycle of There is almost no cooking as the treatment takes place quickly and efficiently after the start of the cycle.

In the first part of the curve, the catalytic cell 16 is partially activated since the total activation temperature of the catalytic cell has not yet been reached.

This figure 3 All the same, it should be noted that carbon monoxide is treated quickly after the start of the cooking cycle. This goal sought by the Applicant has been validated during laboratory tests. The catalytic cell 16 starts to activate from a duration of 4 minutes of operation of the electric heating element 10.

On the figure 4 is shown in dot-dash the temperature regulation of the air contained in the muffle 2, in dashed line end the evolution during the cooking program of the temperature of the catalytic cell 16, in broad dotted line the duration of implementation operation of the gas burner 9 and in continuous line the operating times of the electric heating element 10.

Of course, the higher the temperature of the air contained in the muffle 2, the more efficient the treatment of volatile organic compounds contained in the air.

In addition, when extinguishing the flame of the gas burner 9 the volatile organic compounds are treated by the catalytic cell 16. Said volatile organic compounds are treated since the electric heating element 10 keeps the catalytic cell at a temperature sufficient. Therefore, any risk of danger is removed outside the cooking appliance.

The domestic gas cooking oven 1 as described above thus allows a treatment of volatile organic compounds emitted in the muffle during a cooking program.

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

Claims (18)

1. A method for regulating the temperature in a gas-powered domestic cooking oven comprising a cavity (2) whose front surface (3) is closed by a door (4), and comprising an upper wall (5), side walls (6), a back wall (7), and a lower wall (8), as well as at least one gas burner (9) arranged under the lower wall (8) of said cavity (2) supplied with gas in on-or-off mode, an electric heating element (10) supplied in on-or-off mode arranged under the upper wall (5) of said cavity (2), and said upper wall (5) of the cavity (2) comprising an opening (15) equipped with a catalytic cell (16), characterized in that the method for regulating the temperature comprises the following steps:

   - a first step of raising the temperature of the air contained in the cavity (2) by continuously operating at least one gas burner (9) to a set point temperature (T);

   - during said first step, the electric heating element (10) operates for at least one duration (D1) at a maximum power;

   - a second step of turning off the at least one gas burner (9) for a duration (D2);

   - a third step of continually operating the at least one gas burner (9) for a duration (D3); and

   - then the second and third steps are executed consecutively for a complete cycle of a cooking program.
2. A method for regulating the temperature in a gas-powered domestic cooking oven according to claim 1, characterized in that the setpoint temperature (T) is between 35 and 300°C during a cooking program in said gas-powered domestic cooking oven (1).
3. A method for regulating the temperature in a gas-powered domestic cooking oven according to claim 1 or 2, characterized in that the gas-powered domestic cooking oven (1) comprises an ignition burner adapted to light said at least one gas burner (9).
4. A method for regulating the temperature in a gas-powered domestic cooking oven according to one of the claims 1 to 3, characterized in that the turned-off duration (D2) of the at least one gas burner (9) is in a range of between 1 and 8 minutes.
5. A method for regulating the temperature in a gas-powered domestic cooking oven according to one of the claims 1 to 4, characterized in that the turned-on duration (D2) of the at least one gas burner (9) is in a range of between 30 seconds and 8 minutes.
6. A method for regulating the temperature in a gas-powered domestic cooking oven according to one of the claims 1 to 5, characterized in that the electric heating element (10) is turned on sequentially for sequences of duration (S1) during the first step of the method corresponding to a cooking cycle.
7. A method for regulating the temperature in a gas-powered domestic cooking oven according to claim 6, characterized in that the sequences (S1) of operation during the operating duration (D1) of the electric heating element (10) are in a range of between 5 seconds and 1 minute, and preferably on the order of 25 seconds.
8. A method for regulating the temperature in a gas-powered domestic cooking oven according to one of the claims 1 to 7, characterized in that the electric heating element (10) is turned on simultaneously with said at least one gas burner (9).
9. A method for regulating the temperature in a gas-powered domestic cooking oven according to one of the preceding claims, characterized in that the electric heating element (10) is turned off for a duration identical to the turned-off period (D2) of said at least one gas burner (9) during the second step.
10. A method for regulating the temperature in a gas-powered domestic cooking oven according to one of the preceding claims, characterized in that the electric heating element (10) operates sequentially for sequences of duration (S3) during the third step of the method.
11. A method for regulating the temperature in a gas-powered domestic cooking oven according to claim 10, characterized in that the sequences (S3) of operation during the turned-on duration (D3) of the electric heating element (10) are in a range of between 10 seconds and 1 minute, and preferably on the order of 25 seconds.
12. A method for regulating the temperature in a gas-powered domestic cooking oven according to any one of the preceding claims, characterized in that the electric heating element (10) is operated with a delay of a duration (D4) relative to the turning on of the gas burner (9).
13. A method for regulating the temperature in a gas-powered domestic cooking oven according to claim 12, characterized in that the heating element (10) is turned on with a delay of a duration (D4) ranging from 1 to 30 seconds, and preferably on the order of 2 seconds.
14. A method for regulating the temperature in a gas-powered domestic cooking oven according to one of the preceding claims, characterized in that the turned-on duration (D3) of the at least one gas burner (9) is divided into sequences of duration (S2).
15. A method for regulating the temperature in a gas-powered domestic cooking oven according to claim 14, characterized in that the duration of the sequence (S2) ranges from 20 seconds to 2 minutes, and preferably on the order of 30 seconds.
16. A method for regulating the temperature in a gas-powered domestic cooking oven according to claim 14 or 15, characterized in that the electric heating element (10) operates proportionally to said at least one gas burner (9) in such a way as to adhere to the setpoint temperature (T).
17. A method for regulating the temperature in a gas-powered domestic cooking oven according to one of the claims 14 to 16, characterized in that at least two sequences of duration (S2) may be performed without interruption of the at least one gas burner (9).
18. A method for regulating the temperature in a gas-powered domestic cooking oven according to any one of the preceding claims, characterized in that the gas-powered domestic cooking oven (1) comprises control means suited for turning on and off the gas burner (9) and the electric heating element (10) so as to regulate the temperature of the air contained in the cavity (2) based on a setpoint temperature (T).

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