EP2187131B1 - Device for the detection of a recipient's presence on a cooktop on the gas burner - Google Patents

Description

The present invention relates to a device for detecting the presence of a container on a hob at a gas burner, and a device for igniting and extinguishing a gas burner on a table. cooking device provided with gas burners, in particular a device which makes it possible, when a container is present on said burner, to activate the ignition of the burner and, in the absence of said container, to control the extinguishing of the burner.

In the field of professional catering, the speed of execution of the tasks to be performed is a high requirement. Usually, the cooking is generally started using the maximum power of the burner which is then adjusted by the user. Then, it is very common that, when a cooking is completed or that one must carry out intermediate operations or expectations out of fire, is removed from the cooktop, a container without taking the time to extinguish this fire or even reduce its power. Therefore, it results; an unnecessary dissipation of gas and therefore unnecessary energy consumption and a risk of accidents and significant injury for operators around.

Devices have therefore been proposed to save the energy used during the preparation and cooking of foods that are made on open gas burners.

Thus, in particular, it has been proposed in FR 2,465,163 an energy saving device for cooking hobs which includes a presence detector of a cooking vessel which detects in particular the withdrawal of said container from the hearth. Such a device therefore proposes a detector which under the effect of the presence of the container puts in mechanical contact a rod with an electric contactor placed in series in the power supply circuit of the solenoid valve which controls the main injector of the burner. Thus, in the absence of a container on the burner, the rod is moved away from the contactor and opens the circuit, the coil of the solenoid valve is not supplied with current, the latter is closed and the gas does not reach the burner, this one so it is off. This detector can be a part of the grid pivotally mounted between a non-use position in which it is held projecting slightly above the plane of the hob using a spring and a position of use in which it is lowered into the hob under the effect of a container that is placed on it. This detector can also be a probe mounted projecting through the burner.

Thus, the gate or probe is lowered by the effect of the weight of a container which allows, by the control rod, to actuate the supply circuit of the solenoid valve and ignite the burner. The grid or the probe are held protruding under the effect of spring and are in mechanical connection with the electric contactor via a control rod, so as to distance the contact from the hot zone of the fireplace. In addition, it is also necessary to move away from the hot zone of the hob the spring that allows to project the probe. Indeed, it has been found that the probe being within the burner itself, it is subjected to very high temperatures up to 700 ° C, so it is essential to remove the spring sufficiently to ensure correct operation, since if the burner is too close the spring does not withstand the surrounding temperatures. Also, we arrive at a bulky device.

In most cases, it has been preferred to position a probe of this type with mechanical actuation near the burner but not within this burner. As a result, small containers are not necessarily detected by a feeler positioned next to the burner.

Moreover, such a detection device operates under the effect of the weight of the detected container, this container being of sufficient weight to allow the mechanical actuation of the probe particularly against the elastic return effect of a spring. However, if we put on the hob other than a cooking vessel, for example a tray, a bowl, or even a hand, the probe under the effect of the weight of this object, may cause the ignition of the burner and cause accidents.

Devices of this type reacting to the weight of an object does not therefore have sufficient security.

Heating tables have also been proposed in EP 0 478 061 provided with Joule, radiation or induction heating means having at least one presence detector which detects the presence of a container on at least one hearth, and control means for disabling or reducing the heating of the hearth , the heating table having a timer for reactivating the heating when the detector detects the refitting of the container to the extent that the absence has not lasted beyond a specified period. The detection means may be of the weight-based type, the ultrasonic transceiver, the capacitive or inductive effect of the frequency variation of a high-frequency oscillating circuit, the fact of placing or depositing the cooking utensil influencing the frequency of oscillation which allows to detect or not the presence of the utensil. However, such detection means also do not allow to make a distinction on the type of object placed and are hardly feasible on barefire cooktops. A similar device is also described in EP 0 429 120 .

The present invention therefore has for first purpose to provide a device for detecting the presence of a container on a hob at a burner which allows some recognition of the type of object placed on the hob. The invention also aims to propose a device for igniting and extinguishing a gas burner on a hob provided with gas burners, the device comprising such a device for detecting the presence of a container. on a gas burner of a hob so as to control when detecting the presence of a container on said burner, the ignition of the burner and in the absence of said container, extinguishing the burner.

To this end, the invention relates to a device for detecting the presence of a container on a hob provided with at least one gas burner, as defined in claim 1.

Thus in a simple way by the opening and closing of the electric circuit, it is possible to detect the presence or absence of a cooking vessel. In this way, the laying of an object that would not be an electrically conductive cooking vessel can not be detected. It is thus proposed a specific "electrical" detection device to prevent ignition of the gas burner when the object placed on the hob does not close the electrical circuit, thus avoiding many accidents.

The present invention therefore also relates to an automatic ignition and extinguishing device of a gas burner on a hob provided with at least one gas burner, said burner comprising a pilot, a thermocouple and a pipe supplying gas to said burner, controlled by a solenoid valve, characterized in that it comprises: means for detecting the presence of a receptacle at the burner on the hob, constituted by the detection device consisting of a circuit electrical powered by a source of low voltage electrical current, one of whose terminals is connected to the hob and more precisely to the grid of electrically conductive material of the hob and the other terminal is connected to an electrode housed at the burner, so that in the presence of a container of electrically conductive material placed at the burner, said container comes into contact with the rille and with the electrode, the presence of the container being detected by closing the electrical circuit while the absence of container is detected by the opening of the electrical circuit, and means for management and processing of the detection signal resulting from the opening and closing of the electrical circuit of the detection device for controlling the opening of the solenoid valve provided on the burner pipe when the presence of a container is detected and the closing of said solenoid valve when the absence of a container is detected.

Preferably, the low voltage alternating current source (for example 12V) and the management and processing means consist of conventional electronic components per se, grouped together on an electronic board connected to a mains power supply. It is also possible to provide a current amplifier to facilitate the detection itself in case of poor contact of the container with the electrode and / or the gate and timing means which control a delayed extinction of the burner with respect to the detection of the absence of a container on the burner.

According to one embodiment of the invention, the electrode is mounted in a bore passing through the burner body and the burner cap and is projected from the cap preferably so as to come substantially in the plane of the grid of the cooktop so as to come into contact with a container placed on the cooktop at the burner.

Thus, advantageously, even for a small diameter container, when it is facing the burner, the electrical contact is ensured closing the electrical circuit ensuring the detection of the container.

According to a preferred embodiment of the invention, the electrode carries at its end an electrically conductive probe consisting of a probe body and a detection member mounted displaceably on said probe body between a position called non-detection in which said member is kept protruding from the grid of the hob and a so-called detection position in which said member is driven in displacement so as to disappear under a container. In this way, even if the container is provided with a non-flat bottom, when it is put in place on the burner in question, the sensing member held projecting makes it possible to ensure the contact to close the circuit and thus allow detection of the container.

Preferably, said detecting member is a lever pivotally mounted on the probe body about an axis on the body of the probe in a plane extending perpendicular to the hob, so that the lever having an end provided with 1 ballast, this weighted end maintains the opposite end protruding above the grid of the hob while allowing the pivoting of said lever when a container placed at the burner pushes said projecting end and ensures contact with the electrode via said lever and the probe body. As soon as the container is removed, the weighted end pivots the opposite end so as to bring it back.

Such pivotal mounting on a lever provided with a weighted end avoids having to use return means of the defection member in position such as springs. We therefore offer a probe whose operation is guaranteed and reliable even within the burner and despite the high temperatures that prevail there.

When using a hob, it is also common for the containers filled with food to be heavy and difficult to handle. Also, it is common to move the containers simply by pushing them on the hob, to remove them from the fire or put them back there.

According to a preferred embodiment, the probe body is also rotatably mounted around the electrode. In this way, when a container is moved by simple sliding, the projecting lever abuts against the container that pushes it, which causes the body of the probe to rotate on the electrode. This rotation of the probe advantageously allows an erasure of said lever under the container without risk of tearing it.

The invention also relates to a hob of the fireside type, intended more particularly for professional catering but not exclusively, provided with at least one gas burner and having a device for switching on and off automatically said burner according to the invention.

The invention will now be described in more detail with reference to the drawing in which the figure 1 is a schematic view of a hob provided with a burner ignition and extinguishing device according to the invention;

The figure 2 represents a longitudinal sectional view of a probe of the detection device according to the invention.

The device for detecting the presence of a cooking container 11 conventionally made of electrically conductive material such as stainless steel, aluminum, copper on a hob according to the invention is intended to equip a hob T provided of at least one gas burner 1. A hob is generally itself made of electrically conductive materials.

The burner 1 is fed by a gas supply pipe G whose opening and closing is controlled by a valve 3 of conventional handling per se. Once the gas supply is open, the gas is guided to a pilot 4 and a thermocouple, in a conventional manner per se. Once the heated thermocouple, the gas can be guided to the burner 1 through a pipe 2 controlled by a solenoid valve 5.

The device for detecting the presence of a container consists of an electric circuit powered by a low-voltage electrical power source, one of whose terminals is connected by a conducting wire f1 to the ground m of the table of cooking T and therefore the grit 6 of electrically conductive material of the hob T and the other terminal is connected by a second lead f2 to an electrode 7 housed at the burner 1.

Thus, the electric circuit consisting of the low-voltage alternating current source, the gate 6 and the electrode 7 is open. To close this circuit, it is necessary to electrically connect the gate 6 to the electrode 7. Also, when placing at the burner 1, a cooking vessel 11 generally made of an electrically conductive material and that it- it rests on the one hand on the gate 6 and comes into contact with its bottom with the electrode 7, the electrical circuit is closed. Closing the electric circuit thus gives as information the presence of a cooking vessel 11. Moreover, this detection can be done only in the presence of an object closing the electrical circuit. Therefore, placing the hand on the burner or non-electrically conductive object does not lead to closing the electrical circuit and therefore is not detected,

In the presence of a container 11 of electrically conductive material on the burner 1, said container 11 comes into contact with the gate 6 and with the electrode 7, the presence of the container 11 being detected by closing the electrical circuit while the absence of container is detected by the opening of the electrical circuit.

The detection device thus described is integrated in an automatic ignition and extinguishing device of a gas burner which furthermore comprises means for managing and processing the signal resulting from detection (the closing or opening of the electrical circuit) for controlling the opening of the solenoid valve 5 when the presence of the container 11 is detected and the closing of said solenoid valve 5 when the absence of the container 11 is detected.

Preferably, the low-voltage alternating current source as well as the signal management and processing means corresponding to the detection consist of conventional electronic components per se, grouped together on an electronic card C connected to a section A power supply. also provide on the electronic card, a current amplifier. In this way, even if the contact allowing the closing of the circuit is bad for example, the amplifier allows a detection signal that can be processed.

According to one embodiment, the electrical circuit can be directly the circuit supplying the solenoid valve 5, for example if the solenoid valve 5 operates at low voltage. Thus, the closing and opening of the detection circuit directly controls the solenoid valve.

Thus, when the electric circuit is closed by the presence of a container 11, this closure of the electrical circuit constitutes a signal that the management and processing means process to trigger control means for the opening of the solenoid valve 5 of in order to allow the gas to pass to the hat 1a of the burner 1 which ignites in the presence of the pilot light 4. If the container 11 is removed, the circuit opens and the opening of the circuit constitutes a signal which, treated, allows to trigger the control means for closing the solenoid valve 5 so as to extinguish the burner 1.

Preferably, provision is also made for delay means which, when the absence of the container 11 is detected by the opening of the circuit, make it possible to delay the extinction of the burner 1 with respect to the detection of the absence of a container 11 on the the burner 1. This time delay makes it possible to extinguish the burner 1 after a fixed period, which may be previously determined as being an absence of the container 11 corresponding to a total withdrawal of the container from the fire.

Preferably, the electrode 7 is mounted inside an insulating sheath 7a in a bore passing through the body 1b of the burner 1 and the burner cap 1a and is projecting from said cap 1a so as to come substantially under the plane of the grill 6 of the hob T.

This electrode 7 carries at its end in the example shown a probe 8 comprising a probe body 9 of substantially conical shape provided with an orifice in which is housed the end of the electrode 7 and a detection member 10. The low voltage alternating current produced from the electronic card therefore passes through the electrode 7, the probe 8 with the return by the mass m of the hob T, the container 11 closing the circuit in contact with the probe 8 and the gate 6 of the hob (on the figure 1 it can be seen that the container 11 is slightly above the grid 6 for the sake of clarity of the drawing).

This detection member 10 is pivotally mounted about an axis x extending parallel to the cooking table T, on said probe body 9 between a so-called non-detection position in which said member 10 is kept projecting relative to the grid 6 (see the figure 2 ) and a so-called detection position in which said member 10 is pivotally driven so as to fade under a container 11 placed on the gate 6 at the level of the burner 1.

This detection member is a lever 10 having an end 10a provided with a ballast and pivotally mounted on the body of the probe 9 in a plane extending perpendicularly to the hob T, so that the weighted end 10a maintains the opposite end 10b lighter, for example recessed, projecting above the grid 6 of the hob T while allowing the pivoting of said lever 10 when a container 11 placed on the gate 6 at the burner 1 regrows said projecting end 10b and ensures the contact between the gate 6 and the electrode 7 via said lever 10 and the probe body 9. As soon as the container 11 is removed, the weighted end 10a drives into position. pivoting the opposite end 10b so as to project it over the grill 6.

The probe body 9 is further mounted drivable in rotation around the electrode 7, author of a y-axis. In this way, when a container 11 is moved by simple sliding, the projecting lever 10b abuts against the container 11 and causes the body of the feeler 9 to rotate on the electrode 7. This rotation of the probe 8 allows an erasure said lever 10 under the container 11 without risk of tearing said lever 10. This end 10b preferably has a rounded shape to facilitate erasure under the container 11.

Thus, the feeler 8 and the electrode 7 are mounted in the center of the burner 1 and are therefore subjected to very high temperatures in operation but allow detection of small containers. The detection lever 10 does not need a spring to be returned to the non-detection position, so it is houseable in the center of the burner 1 without the very high operating temperatures do not interfere with its operation.

An electronic card may be provided for each burner 1 or an electronic card may be provided on which all the burners are managed.

Preferably, it is expected that the grid 6, the probe 8, the hat 1a of the burner, the body of the burner 1b and the bowl of cleanliness 12 of the hob T are removable for cleaning.

The invention is of course in no way limited to the examples described given by way of illustration but encompasses all the variants falling within the scope of the definition of the invention as defined in the claims.

Claims (12)

1. Device for detecting the presence of a recipient (11) intended for a cooktop (T) provided with at least one gas burner (1), said device consisting of an electric circuit powered by a low-voltage electric current source with two terminals, characterised in that the cooktop comprises a grid (6) made of electrically conducting material, and in that one of the terminals is connected to the cooktop (T) and more specifically to the grid (6) and the other terminal is connected to an electrode (7) housed in at least one of said burners (1), such that, in the presence of a recipient (11) made of electrically conducting material on the burner (1), said recipient (11) comes into contact with the grid (6) and with the electrode (7), the presence of the recipient (11) being detected by the closing of the electric circuit whereas the absence of a recipient (11) is detected by the opening of the electric circuit.
2. Device for detecting according to claim 1, characterised in that the electrode (7) is mounted in a bore through the body of the burner (1b) and the burner cap (1a) and is mounted on the cap (1a) so as to come into contact with a recipient (11) placed on the cooktop (T) at the burner (1).
3. Device for detecting according to claim 2, characterised in that the electrode (7) further comprises, at the end thereof, an electrically conducting sensor (8) consisting of a sensor body (9) and a detection member (10) movably mounted on said sensor body (9) between so-called non-detection position wherein said member (10) is kept over the grid (6) of the cooktop (T) and a so-called detection position wherein said member (10) is moved so as to disappear under a recipient (11) placed at the burner on the grid (6).
4. Device for detecting according to claim 3, characterised in that said detection member is a lever (10) pivot-mounted about an axis (x) on the sensor body (9) in a plane extending perpendicular to the cooktop (T), and having one end (10a) provided with a ballast such that said ballasted end (10a) holds the opposite end (10b) over the grid (6) of the cooktop (T) while enabling pivoting of said lever (10) to push said mounted end (10b) back under the effect of the positioning of a recipient (11).
5. Device for detecting according to any of claims 3 and 4, characterised in that the sensor body (9) is rotatably mounted about the electrode (7).
6. Device for automatically igniting and extinguishing a gas burner (1) on a cooktop (T) provided with at least one gas burner (1), said at least one burner (1) comprising a pilot light (4), a thermocouple and a conduit (2) supplying said at least one burner (1) with gas, controlled by an electrovalve (5), characterised in that it comprises:

   means for detecting the presence of a recipient (11) on at least one of said burners (1) on the cooktop (T), consisting of the device according to any of claims 1 to 5,

   means for managing and processing the detection signal to control the opening of the electrovalve (5) provided on the conduit (2) of the burner (1) when the presence of a recipient (11) is detected and the closing of said electrovalve (5) when the absence of a recipient (11) is detected.
7. Device for igniting and extinguishing according to claim 6, characterised in that said low-voltage alternating current source and the management and processing means are grouped together on an electronic board connected to a mains power supply (A).
8. Device for igniting and extinguishing according to any of claims 6 and 7, characterised in that a current amplifier is provided.
9. Device for igniting and extinguishing according to any of claims 6 and 7, characterised in that time delay means are provided, controlling delayed extinguishing of at least one of said burners (1) with respect to the detection of the absence of a recipient (11) of said at least one burner (1).
10. Device for igniting and extinguishing according to any of claims 6 to 9, characterised in that one electronic board is provided for each burner (1).
11. Ignition and extinguishing device according to any of claims 6 to 9, characterised in that an electronic board is provided for managing all the burners (1).
12. Cooktop provided with at least one burner, characterised in that it comprises a device for automatically igniting and extinguishing said burner according to any of claims 6 to 11.

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