ITTO20060728A1 - GAS COOKING APPLIANCES WITH AUTOMATIC VALVES WITH A SAFETY SYSTEM - Google Patents

Description

"GAS COOKING APPLIANCE WITH AUTOMATIC VALVES WITH A SAFETY SYSTEM"

SUMMARY

The present invention relates to a gas cooking appliance equipped with a gas connection (AG) and one or more gas burners (B1, B2, B3, B4); it comprises an automatic general valve (VG) having an inlet associated with said connection (AG), one or more individual automatic valves (V1, V2, V3, V4) having outputs associated respectively with said one or more burners (B1, B2, B3 , B4), and a conduit (TU) which connects the output of the general valve (VG) to the inlets of said one or more individual valves (V1, V2, V3, V4); it also comprises an electronic safety system (EL) suitable for detecting anomalies and / or failures such as to cause unwanted gas flow at least through said general valve (VG).

DESCRIPTION

The present invention refers to a gas cooking appliance with automatic valves according to the preamble of claim 1.

Gas cooking appliances, in particular gas hobs, with automatic valves are not widespread on the market even though this type of appliance is foreseen in the regulations, for example by the European standard EN 30-1-4 relating to safety.

In these appliances, the gas regulation for a burner is carried out by means of an automatic valve, that is a valve whose regulating organ is not operated directly and manually by the user but is operated by an automatic device (for example electric); this automatic device can be controlled by a manual command of the user (for example a knob, a cursor, a button, a key, a touch device, ...) and / or by an automatic command generated for example on the basis of the detection of a sensor.

For these appliances, the aforementioned legislation provides that there are two valves in series along the gas line leading to a burner; in this way, if one valve fails or malfunctions, the other valve should ensure that there is no unwanted leakage of gas from the line. However, the Applicant has noted that if after the failure or malfunction of one of the two valves there should also be a failure or malfunction of the other of the two valves (this could happen after weeks or months or years), there could be unwanted gas escaping from the line and the user would have no way of noticing it.

Moreover, a hob is usually equipped with four or five burners. In this case, using known technologies, it would be necessary to provide eight or ten valves in the hob; this involves a high cost (both direct and indirect) and a large footprint.

The general purpose of the present invention is to provide a gas cooking appliance with automatic valves that complies with the regulations regarding safety and overcomes the drawbacks of the known art.

A first particular object of the present invention is to find a solution which is simple and reliable.

A second particular object of the present invention is to find a solution which integrates well with automatic valves, in particular with automatic valves of the piezoelectric type.

These and other purposes are achieved by the appliance having the characteristics set out in the appended claims which form an integral part of this description.

The idea behind the present invention is to provide in the household appliance a single individual automatic valve for each burner and an additional general automatic valve for the entire household appliance as well as an electronic safety system suitable for detecting anomalies and / or faults such as to cause unwanted gas flow at least through the general valve, but also preferably through the individual valves.

In this way, on the gas line leading to each burner there are always two automatic valves in series and it is also possible to check the correct operation of the valves and therefore of the appliance as regards the gas circuit.

According to a further aspect, the present invention further relates to a gas detector, as well as a gas distribution block, particularly suitable for use in the cooking appliance according to the present invention.

The present invention will become clearer from the following description to be considered in conjunction with the accompanying drawings in which:

Fig.1 shows a simplified block diagram of a first household appliance according to the present invention in which only the relevant blocks for the description of the invention are present,

Fig. 2 shows a simplified block diagram of a second household appliance according to the present invention in which only the relevant blocks for the description of the invention are present,

Fig. 3 shows a simplified block diagram of a third household appliance according to the present invention in which only the relevant blocks for the description of the invention are present,

Fig. 4 shows a simplified block diagram of a fourth household appliance according to the present invention in which only the relevant blocks for the description of the invention are present,

Fig. 5 shows a schematic sectional view of a first gas detector according to the present invention,

Fig.6 shows a schematic sectional view of a second gas detector according to the present invention, together with a part of a gas distribution block.

Both this description and these drawings are to be considered for explanatory purposes only and therefore not limitative.

The examples of Fig.1, Fig.2, Fig.3 and Fig.4, although different, are similar to each other in terms of architecture and components; therefore the same references have been used to indicate corresponding components.

The examples in Fig. 1, Fig. 2, Fig. 3 and Fig. 4 refer to a gas cooker hob equipped with an AG gas connection and four gas burners B1, B2, B3 and B4. The gas hob is a household appliance in which the present invention finds excellent application; another household appliance in which the present invention finds excellent application is the gas oven, or the gas cooker, any household appliance comprising at least a gas hob and a gas oven being called a "gas cooker".

As is known, the gas must be supplied to the burners and is then brought from the AG connection to the burners B through a series of ducts; four gas lines are therefore identified that carry the gas from the AG connection to the four burners B1, B2, B3, B4 respectively; along these lines, valves are needed to open, close and regulate the gas to the burners.

The examples of Fig.1, Fig.2, Fig.3 and Fig.4 include a general valve VG and four individual valves V1, V2, V3, V4 for the corresponding burners B1, B2, B3, B4. These valves are automatic and are, in particular, of the piezoelectric type; on the market there are already automatic piezoelectric valves for gases produced for example by FESTO, SERVOCELL and DIAMOND H. The general valve VG is placed in the gas circuit in such a way that all the gas flows passing through the individual valves V1, V2 , V3, V4 also pass through the general valve VG; therefore, if the general valve VG is closed there can be no gas flow through any of the individual valves V1, V2, V3, V4. The valves V1, V2, V3, V4 are individually associated with the burners B1, B2, B3, B4 and are used to individually open, close and regulate the gas flow to these burners.

In Fig.1, Fig.2, Fig.3 and Fig.4 a gas pipe TU is highlighted that connects the output of the VG valve to the inlets of all the valves V1, V2, V3, V4. In the case of Fig.1 and Fig.3, it is a branched duct; in the case of Fig.2 and Fig.4, it is a simple duct which is coupled to a collector duct CO.

The examples of Fig.1, Fig.2, Fig.3 and Fig.4 also include a general detector of RG gas flow; the general detector RG is such as to detect gas flow through the general valve VG; but the general detector RG (due to its position) is also able to detect gas flow through any of the individual valves V1, V2, V3, V4 without being able to determine which one.

The examples of Fig.3 and Fig.4 further include four individual detectors of gas flow R1, R2, R3, R4; the individual detector R1 is such as to detect gas flow through the individual valve V1 and therefore substantially the gas flow that reaches the burner B1; the individual detector R2 is such as to detect gas flow through the individual valve V2 and therefore substantially the gas flow that reaches the burner B2; the individual detector R3 is such as to detect gas flow through the individual valve V3 and therefore substantially the gas flow that reaches the burner B3; the individual detector R4 is such as to detect gas flow through the individual valve V4 and therefore substantially the gas flow that reaches the burner B4.

All the valves VG, V1, V2, V3, V4 are electrically controlled; for this purpose they are suitable for receiving electrical control signals SVG, SV1, SV2, SV3, SV4. All the R1, R2, R3, R4, RG gas flow detectors are able to generate electrical detection signals SR1, SR2, SR3, SR4, SRG indicative of the detected gas flow. These can be of the active type, that is to say that they receive electrical power and autonomously emit an electrical signal indicative of the gas flow detected, or of the passive type, that is to say that connected to an external electric or electronic circuit they determine a signal in this circuit. electrical indicative of the detected gas flow (the simplest example is a contact controlled by the gas flow). One or more of these gas flow detectors, in particular the general detector RG, is able to generate a signal indicative of the gas pressure inside the duct TU (and therefore in the case of Fig. 2 and Fig. 4 at the inside the CO duct); in this situation, this signal is also indicative of the gas flow inside the TU duct (and the CO duct if present) if it is considered for a sufficiently long time interval as will be clarified below.

The electrical signals mentioned above, whether they are for control or detection, can be of the digital or analogue type depending on the type of valve and detector.

The examples of Fig.1, Fig.2, Fig.3 and Fig.4 include an electronic control system of the gas appliance schematized with an EL block designed to control all the functions of the appliance.

An important function performed by the EL system is that of controlling the gas flow to burners B1, B2, B3, B4; for this purpose, the EL system is connected to valves VG, V1, V2, V3, V4 and can be connected to a control panel (not shown in the figures) equipped for example with knobs and / or buttons and / or keys (for example touch example) and one or more displays in such a way as to be able to receive the commands for setting the flame level from the user, generate the control signals SVG, SV1, SV2, SV3, SV4 and provide information to the user on the flame level set. Another important function performed by the EL system is that of a security system; for this purpose, the EL system is connected to the general detector RG (in all cases of the figures) and to the individual detectors R1, R2, R3, R4 (only in the cases of Fig. 3 and Fig. 4) in such a way as to receive the detection signal SRG (in all cases of the figures) and the detection signals SR1, SR2, SR3, SR4 (only in the cases of Fig.3 and Fig.4).

It is good to clarify immediately that the number of valves and the number of detectors depends on the implementation of the present invention.

The embodiment examples of Fig. 2 and Fig. 4 differ from the embodiment examples of Fig. 1 and Fig. 3 in that some of the components are integrated to form a gas distribution block AS equipped with one gas inlet and four separate gas outlets. In particular, block AS comprises a collector duct CO in which the valves V1, V2, V3, V4 are housed and integrates the general detector RG; moreover, in the case of the example of Fig.4, the CO collector duct integrates the detectors R1, R2, R3, R4 which are associated respectively with the four gas outlets.

Fig.5 schematically shows a first gas detector R which is adapted to be used in the household appliance according to the present invention. This can be, for example, associated, in particular applied or mounted, at the inlet or outlet or inside a gas valve.

The detector R could for example constitute the heart of the general detector RG, which can be a separate device placed in any point of the tube TU, or included in an assembly comprising the general valve VG, or (as shown in Fig. 5) located at the entrance to block AS of Fig.2 and Fig.4; it is for this reason that in Fig. 5 the collector duct CO of block AS is visible.

The detector R is not able to measure the (analog) value of the gas pressure (inside the CO pipe and therefore inside the TU pipe connected upstream of the CO pipe), but simply to signal two pressure states of gas. To be precise (as will become clearer from the following), the detector R of Fig. 5 is able to indicate whether the gas pressure in the CO collector duct corresponds to pressure values substantially equal to the atmospheric pressure (i.e. to an interval around the atmospheric pressure) or if the gas pressure in the CO collector duct corresponds to pressure values higher than atmospheric pressure.

In the duct CO enters a flow of gas from the duct TU typically in the direction indicated by the arrow F; the detector R comprises a membrane M the edges of which are fixed to the edges of an opening of the duct CO; the detector R also comprises a rod A, a lever L (at least a portion of which is made of electrically conductive material), an electric contact C1 and two terminals T1 and TL respectively electrically connected to the contact C1 and to the lever L. The pressure at The outside of the CO duct corresponds to the atmospheric pressure.

In the example shown for purely explanatory but not limiting purposes in Fig. 5, the rod A is constrained to the membrane M in such a way as to move substantially upwards and downwards respectively when the central part of the membrane M moves towards up and down due to the pressure in the CO duct.

The lever L is constrained to one of its extremities (left in Fig. 5), in such a way as to be able to rotate around this extremity, and to the rod A in such a way as to rotate upwards and downwards respectively when the rod A moves up and down. When the lever L is fully rotated upwards, it touches contact C1 and therefore there is an electrical path between terminal T1 and terminal TL (and therefore a corresponding electrical signal).

For clarity, the membrane M, the rod A, the lever L are in a position (in particular higher) such that they touch the contact C1 when the pressure in the duct CO is higher than the atmospheric pressure PA at least by a predetermined value P1, that is, when the pressure in the CO duct assumes a value equal to at least PA + P1; for pressure values lower than PA + P1, the lever L is in one of the many positions (in particular lower) for which it does not touch C1.

The detector R is therefore a very simple electromechanical device which allows to perform effective (typically in a gas cooking appliance) gas pressure measurements and, as will be clarified below, also gas flow detection.

The detector R is designed in such a way that the lever L touches the contact C1 during normal operation of the cooking appliance (ie when there is gas flow in the CO duct in the direction indicated by the arrow).

In conditions of unused cooking appliance (i.e. with valves VG, V1, V2, V3, V4 all closed by the electronic safety system EL), any gas leak through the general valve VG causes the pressure to the inside of the ducts TU and CO grows until it reaches the threshold value PA + P1 which determines the closure of the electrical contact between L and C1, thus allowing the detection of the aforementioned leak by the electronic safety system EL.

It is clear that instead of a simple lever it is possible to use more complex levers and that the membrane M can be of any shape and can be replaced with another mobile element due to the gas pressure.

Fig.6 schematically shows a second gas detector R which is adapted to be used in the household appliance according to the present invention. This can be, for example, associated, in particular applied or mounted, at the inlet or outlet or inside a gas valve.

In Fig.6, the detector R could for example constitute the heart of the general detector RG located at the entrance of block AS of Fig.2 and Fig.4; it is for this reason that in Fig. 6 the CO collector duct of block AS is visible as well as a first automatic piezoelectric valve V1 also associated with the CO collector duct, as will be clarified further below. Adjacent to the collector duct CO, there is a chamber CP in which the live electronic components of the gas distribution block AS are housed. Under normal operating conditions of the appliance according to the present invention, the CP chamber is at atmospheric pressure PA, while in the event of an explosion inside the CP chamber, this pressure rises to a value significantly higher than the atmospheric pressure PA.

The detector R is able to simply signal three states of differential pressure of gas between the chamber CP and the collector duct CO. To be precise (as will become clearer from the following), the detector R of Fig. 6 is able to indicate whether the gas pressure PCO in the CO duct is higher by at least a predetermined value P1 than the gas pressure PCP in the chamber CP, if the gas pressure PCO in the CO line is lower by at least a predetermined P2 value than the gas pressure PCP in the chamber CP, or if the PCO and PCP pressures are such that PCO <PCP + P1 and PCO> PCP-P2. In the duct CO enters a flow of gas from the duct TU typically in the direction indicated by the arrow F; the detector R comprises a membrane M the edges of which are fixed to the edges of an opening of the duct CO; the detector R also comprises a rod A, a lever L (at least a portion of which is made of electrically conductive material), a first electrical contact C1, a second electrical contact C2 and three terminals T1 and T2 and TL respectively electrically connected to the contact C1 and to the contact C2 and to the lever L. In the example shown for purely explanatory but not limiting purposes in Fig. 6, the rod A is constrained to the membrane M in such a way as to move substantially upwards and downwards respectively when the central part of the membrane M moves up and down due to the pressure difference between the duct CO and the chamber CP.

The lever L is constrained to one of its extremities (left in Fig. 6), in such a way as to be able to rotate around this extremity, and to the rod A in such a way as to rotate upwards and downwards respectively when the rod A moves up and down. When the lever L is fully rotated upwards, it touches the contact C1 and therefore there is an electrical path between terminal T1 and terminal TL (and therefore a corresponding first electrical signal); when the lever L is turned totally downwards it touches the contact C2 and therefore there is an electrical path between the terminal T2 and the terminal TL (and therefore a corresponding second electrical signal).

It should be noted that alternatively the electrical detector could be able (with the aid of a simple electrical circuitry) to generate a single electrical signal at two of its terminals; for example, a zero voltage signal when the lever L does not touch either of the two contacts C1 and C2, positive when the lever L touches the contact C1 and negative when the lever L touches the contact C2.

For clarity, the membrane M, the rod A, the lever L are in the upper position (and touch the contact C1) when the pressure PCO in the duct CO is higher than the pressure PCP in the chamber CP at least by a predetermined value P1, i.e. PCP + P1, while they are in the lower position (and touch the contact C2) when the pressure PCO in the conduit CO is lower than the pressure PCP in the chamber CP at least by a predetermined value P2, PCP-P2; for pressure values between PCP + P1 and PCP-P2, the lever L is in one of the many intermediate positions and does not touch either C1 or C2.

The detector R is therefore a very simple electromechanical device which allows to perform effective (typically in a gas cooking appliance) gas pressure measurements and, as will be clarified below, also gas flow detection.

It is clear that instead of a simple lever it is possible to use more complex levers and that the membrane M can be of any shape and can be replaced with another mobile element due to the gas pressure.

The detector R is designed in such a way that the lever L touches the contact C1 during normal operation of the gas appliance (i.e. when there is gas flow in the CO duct in the direction indicated by the arrow) and that the lever L does not it should touch neither of the two contacts C1 and C2 when the hob is not in use (i.e. none of its burners are on).

In order to highlight some advantageous aspects of the detector R of Fig.6 it is now good to describe the automatic gas valve of Fig.6; It is worth remembering that, in Fig. 6, both the detector and the valve are represented in a very schematic way and are not to be understood in a limiting sense.

In Fig.6, an automatic piezoelectric type valve is shown and is indicated as a whole with the reference V1 due to the fact that it could be for example the valve V1 of the appliance in Fig.2 or Fig.4.

2 indicates a piezoelectric element which acts as an actuator of a regulating member 3 of the valve V1; 31 is the shutter of the valve 1 which is part of the regulating organ 3; 32 is a stem of the regulating member which is part of the regulating member 3 of the valve V1.

The shutter 31 and the stem 32 are rigidly joined together to form the adjustment member 3 which is pushed by the actuator 2.

Actuator 2 receives an electrical signal S1 through two electrical conductors; the actuator 2 is made in such a way that when a direct electric voltage is applied as a signal S1 it bends downwards and the adjustment member 3 translates correspondingly downwards; the greater the amplitude of the voltage signal S1 the greater the curvature of the actuator 2.

The valve V1 of Fig.6 comprises a hollow body 6 which is associated with the collector conduit CO; the conduit CO acts as the gas inlet conduit of the valve V1; then there is an outlet conduit for gas 8 which connects the valve V1 to the burner B1. The cavity of the body 6 is delimited at the bottom by a rigid wall 4 which corresponds to a wall of the duct CO); the duct 8 begins in the cavity of the body 6. The wall 4 has an opening 40 (a countersunk hole) for the passage of gas from the duct CO to the cavity of the body 6.

The shutter 31, for example with a conical shape, is adapted to close the opening 40 of the wall 4 by coupling perfectly with this in order to create a seal.

Furthermore, an elastic element, in particular a spring, can be provided to obtain or facilitate the return of the valve V1 to its rest or inoperative condition; in the case of the example of Fig. 6, the downward movement of the adjustment member 3 is obtained thanks to the actuator 2 and the upward movement of the adjustment member 3 is obtained thanks to the elastic element (not shown in the figure).

The body 6 of the valve V1 of Fig. 6 has a hole in its upper part which allows the stem 32 to slide inside it but not substantial gas leaks from the cavity of the body 6. In particular, in the valve V1 of Fig.6 , the upper wall of the body 6 is not rigid; this wall is made by means of a diaphragm 9, for example a membrane of elastic material, for example circular or square. In particular, this diaphragm 9 is shaped in such a way as to increase its surface; in fact, the loops around the stem 32 can be seen in the figure.

The diaphragm 9 is substantially hermetically fixed both to the walls of the body 6 and to the stem 32; thanks to its elasticity it allows the stem 32 and therefore inside the regulating organ 3 of the valve V1 to move in particular vertically and does not allow any gas present in the cavity of the body 6 to escape except through the duct 8.

To understand the effect of the diaphragm 9 it is necessary to consider the valve V1 of Fig. 6 during its operation.

When the valve V1 is closed, in the cavity of the body 6 the pressure corresponds to the pressure downstream of the duct 8 (basically downstream of the burner not shown), ie the atmospheric pressure; the same pressure is also found outside the body 6; in this condition the force exerted by the pressure on the outside and on the inside of the diaphragm is equal and therefore the diaphragm does not transmit any force to the stem 31 and therefore to the whole organ 3. When the valve begins to open, that is when the organ 3 begins to drop, the pressure in the body cavity 6 rises a little and therefore on the diaphragm 9 acts a small upward force directly proportional to its surface and to the pressure difference between the body cavity 6 and the PCP pressure of the CP chamber; this force is exerted on the member 3 and is directed upwards and therefore tends to resist the downward force exerted by the element 2. When the valve is completely open, the pressure in the cavity of the body 6 is maximum and so the resisting force is maximum and therefore tends to close the valve again.

For the design of the diaphragm 9 it must be taken into account that the pressure in the gas pipes is generally only 20-30 mBar higher than atmospheric pressure. It is for this reason that it is generally necessary to increase the surface of the diaphragm 9 in order to exploit its resistant effect; indicatively and in particular for valves that connect to 1⁄4 inch GAS pipes, the extension of the diaphragm 9 has a characteristic dimension (diameter or side) between 10mm and 30mm, preferably between 15mm and 20mm.

As can be seen in Fig. 6, the block AS has a CO duct common to the detector R and to all the valves of the block (only the valve V1 is shown) and a chamber CP adjacent to the CO duct (and hermetically separated from the CO duct) . In Fig. 6, this chamber houses both the detector R and the valve V1, as well as the other individual valves not shown.

Contact C2 is used to detect a particular fault in the AS block. In fact, it can happen (naturally very rarely) that explosions occur inside the CP chamber mentioned above which can damage one or more of the valves included in block AS, for example valve V1; in this case, the pressure in this chamber CP exceeds the pressure in the duct CO for a short instant and thanks to the contact C2 this situation can be detected and it is possible, for example, to decide to close the valve VG.

The aforementioned explosions can occur, for example, if the membrane M of the detector R or one of the diaphragms of the individual valves V1, V2, V3, V4 is damaged (for example, the diaphragm 9 of the individual valve V1 represented in Fig. 6), so to compromise its hermetic seal and therefore allow a flow of gas to pass from the collector duct CO to the chamber CP, and subsequently a failure occurs in one of the live components such as to generate a spark inside the chamber CP.

In order to avoid an explosion after damage to the membrane M or the diaphragm 9, the present invention allows to identify, during normal operation of the gas appliance, the variation of the PCP pressure inside the chamber CP following the aforementioned damage. In fact, the detector R is designed in such a way that the lever L touches the contact C1 during normal operation of the gas appliance: a damage to the membrane M or to the diaphragm 9 tends to reduce the pressure difference between PCO and PCP, ergo lever L moves away from contact C1. If this decrease in the pressure difference is not followed by a flame extinction detection in one of the active gas burners B1, B2, B3, B4, the electronic control system EL deduces that damage to the membrane M or to the diaphragm 9.

On one of the walls of the chamber CP not contiguous to the duct CO there is a calibrated hole 89 which has the function of allowing the leakage through it of a very limited and therefore not dangerous gas flow.

As mentioned before, various types of gas flow detectors can be advantageously integrated into the automatic valves used in the household appliance according to the present invention; it is advantageous to use a gas flow detector capable of generating an electrical signal indicating only two gas flow states, in particular the substantial absence of gas flow and the substantial presence of gas flow.

A first possibility consists in integrating a flow detector of the type capable of generating an electrical signal linked to the pressure difference, in particular the pressure detected in a first direction and the pressure detected in a second direction substantially perpendicular to said first direction.

A second possibility consists in integrating a flow detector of the type designed to generate an electrical signal linked to the displacement or position of a regulating member of at least one corresponding valve, and therefore indirectly the flow of gas through the valve. Such displacement or position could be detected through one or more simple electrical contacts.

A third possibility consists in integrating a detector like the one in Fig.5 or Fig.6.

In general, a gas cooking appliance according to the present invention is equipped with a gas connection and one or more gas burners; it includes :

- an automatic general valve having an inlet associated with said connection, - one or more automatic individual valves having outputs associated respectively with said one or more burners, and

- a conduit that connects the output of the general valve to the inlets of said one or more individual valves;

in addition, it includes an electronic safety system (advantageously integrated into the electronic control system of the appliance) designed to detect anomalies and / or failures such as to cause unwanted gas flow at least through the general valve.

In this way, on the gas line that leads to each burner there are always two automatic valves in series and the number of valves is reduced to a minimum and it is also possible to check the correct operation of the valves and therefore of the appliance as regards the circuit of the gas.

Typically, the household appliance according to the present invention will comprise more than one burner and correspondingly more than one individual valve; in the most typical applications it will range from a minimum of two to a maximum of seven.

It is advantageous to provide that a gas flow detector is placed in such a way as to detect gas flow through any of the individual valves. As is clear from the examples described, with a single detector placed for example along the duct that connects the output of the general valve to the inlets of the individual valves, it is possible to detect flow both through the general valve and through any of the individual valves.

Furthermore, it may be advantageous to provide that the electronic safety system is further adapted to detect anomalies and / or failures such as to cause unwanted gas flow through each of the individual valves. This can be achieved by providing for example a flow detector for each individual valve at its inlet or inside or at its outlet.

Advantageously, the safety system is able to generate an alarm signal, in particular an acoustic signal and / or a visual signal in the event of said anomalies and / or failures; in this way, the user can on the one hand decide not to use the appliance and, on the other hand, request the intervention of technical assistance.

Furthermore, if the appliance, in particular its electronic control system, is connected to a communication network, the security system may be able to send information to a remote center and automatically request the intervention of technical assistance.

It may also be envisaged that the safety system is designed to prevent the appliance from functioning in the event of such anomalies and / or failures; this makes the appliance safer. This operation blocking action could be taken for example only in case of anomalies and / or serious failures. The general automatic valve of the household appliance according to the present invention can act as a safety valve and preferably be of the electromagnetic type placed upstream of the individual automatic valves; typically, this valve is of the type able to have only two operating conditions: valve fully open and valve closed. In this case, the safety system may be able to close said safety valve in the event of said anomalies and / or failures.

In any case, it can be decided to regulate the gas flow only through the individual valves; in this case, the general valve can be of the type adapted to have only two operating conditions (valve fully open and valve closed), in particular of the electromagnetic type. The above security measures can also be combined with each other. It is possible to provide at least one individual gas flow detector placed downstream or upstream respectively of at least one of the valves in such a way as to detect gas flow through said valve; in particular, as in the examples of the figures, there can be a detector for the general valve and possibly a detector for each individual valve. In this case, it may be advantageous for the detector to be associated, in particular applied or integrated, to the inlet or outlet of said individual valve. The gas flow detector can also be integrated into the individual valves.

For the purpose of detecting faults or anomalies, it is of the utmost interest to be able to verify above all whether an automatic valve is open despite a closing control signal; in fact, in this case, there is a risk of unburned gas (ie without flame) escaping from the burner.

In general, it is of interest to detect such a condition as soon as it occurs and preferably report it to the user before this condition can cause irreparable damage to people and / or property.

If you are interested in the appliance being able to accurately self-diagnose any faults and / or anomalies, it will be important to know exactly which valve is faulty or abnormal and, according to the present invention, a greater number of flow detectors will therefore be required. of gas.

The type of automatic valve which is best suited for the present invention is that of the piezoelectric type; this applies not only to the general valve, but especially to the individual valves; as regards the possible safety valve (which may correspond precisely to the general valve), an electromechanical valve, for example electromagnetic, will instead be appropriate.

For the purposes of the present invention, to identify in which valve a gas leak may have occurred, it is sufficient that the gas flow detectors are suitable for generating an electrical signal indicating two gas flow states, in particular the substantial absence of gas flow and the substantial presence of gas flow; this makes it possible to simplify their structure and therefore to reduce their dimensions and considerably reduce their cost. The two main checks to be carried out are in fact:

A) if no gas flow corresponds to the valve with the control signal in closing,

B) if a gas flow corresponds to the valve with the control signal on opening.

An effective system for detecting the gas flow provides for the generation of an electrical signal linked to the pressure difference, in particular the pressure detected in a first direction and the pressure detected in a second direction substantially perpendicular to said first direction; as is known, this is the principle behind the Pitot tube, a device that is used in the aeronautics sector to measure the speed of air.

Another effective system for detecting the gas flow is particularly suitable for being integrated into an automatic valve and provides for the generation of an electrical signal related to the displacement or position of the valve shutter. In this case, it is an indirect flow measurement, but more than sufficient for the purposes of the present invention: if the shutter is in the closed position there is no flow and if the shutter is not in the closed position there is it is flow (small or large). As already mentioned, the household appliance according to the present invention can comprise an electronic safety system advantageously integrated into the electronic control system of the appliance; this integration is easier if the electronic control system is based on a microprocessor or microcontroller and provides for control programs that determine the operation of the system and therefore, through actuators and sensors, the operation of the appliance.

This safety system can be designed for a simple reporting of anomalies and / or faults or for a complete and precise self-diagnosis aimed at the user and / or technical assistance staff (for example the repair technician); in this context it is also useful to think of forms of reporting and / or remote technical assistance since the consequences of anomalies and / or breakdowns of gas cooking appliances can have very serious consequences for users, for example explosions.

The electronic safety system can be adapted to carry out repeatedly and / or cyclically at least one procedure to check the correct operation of the general valve and / or of one or more of the individual valves, typically of all.

There are various possible verification procedures in relation to the number and type of detectors used in the appliance. For example, gas flow detectors and / or gas flow variation detectors and / or gas pressure detectors and or gas pressure variation detectors can be used. Such detectors can be placed in correspondence with valves or along ducts, in particular along a duct which connects the general valve to the individual valves.

A verification procedure can be performed each time one of the individual valves is closed. In fact, after the closure of an individual valve, the gas flow that passes through it must be zero if the valve works correctly.

For this verification, through a gas flow detector associated with each individual valve, the general valve can be left open and check that after the closure of an individual valve the gas flow that passes through it is effectively zero; this check can be carried out in a very short time (for example ten milliseconds).

A check procedure can be carried out each time the main valve is closed; this closure can occur, for example, when the user has decided to turn off all the burners. In fact, after the general valve is closed, the gas flow that passes through it must be zero if the valve works correctly.

To make this check by means of a gas flow detector associated with this general valve, at least one individual valve can be left open and check that after the general valve is closed, the gas flow that passes through it is effectively zero; this check can be carried out in a very short time (for example ten milliseconds).

To verify the perfect closure of one or more of the individual valves (or of a gas distribution block), through a pressure detector associated with a pipe that connects the general valve to the individual valves, you can first close all the individual valves, then close the general valve and then check that the pressure in the duct remains constant and does not decrease due to leaks due to the imperfect closure of one or more of the individual valves (or for example of a gas distribution block); this verification requires some time (for example a few seconds).

On the other hand, to check that the main valve is perfectly closed through a pressure detector associated with a pipe that connects the general valve to the individual valves, you can first close the general valve, then close all the individual valves (to empty the pipe) and then check that the pressure in the duct remains constant and does not increase due to leaks due to the imperfect closure of the general valve; this verification requires some time (for example a few seconds).

The two verification procedures mentioned above can be performed in succession to each other to carry out a verification cycle to be repeated preferably at each cycle of use of the gas appliance: for example, the general valve verification procedure can be carried out at the beginning. of a use cycle and the procedure for checking the individual valves at the end of each use cycle (or vice versa), or both checks can be carried out at the beginning or at the end of each use cycle. A verification procedure can be carried out at each opening of the main valve; this opening can occur, for example, when the burners are all off and after the user has decided to light one of the burners; once the check is complete, one of the individual valves can be opened for the use of the corresponding burner.

Of course, many other verification procedures are possible.

A complete verification procedure can be carried out cyclically (for example once an hour or once a day) during periods of non-use of all the burners of the appliance, i.e. after the user has supplied the electronic system appliance control commands such as to turn off all burners; in a domestic kitchen, these periods of time represent most of the appliance's life and can be usefully exploited to keep the appliance under control and ensure maximum safety.

During these periods of non-use of all the burners of the appliance, the automatic valves are preferably kept all closed by the safety system (for example by not feeding them) often integrated into the control system.

The full verification procedure may include one or more of the following steps:

- check of the main valve,

- check of a generic individual valve or of a gas distribution block comprising several individual valves,

- verification of each specific individual valve.

As said, according to a specific aspect, the present invention also relates to a gas detector.

In general, the gas detector according to the present invention can be adapted, according to a first embodiment, to generate at least one electrical signal indicating only two pressure states inside a duct or chamber containing gas; in particular, a first of said pressure states corresponds to pressure values inside said duct or chamber substantially equal to the pressure outside and a second of said pressure states corresponds to pressure values inside said duct or of said chamber higher than the pressure outside.

The gas detector according to the present invention can be adapted, according to a second embodiment, to generate at least one electrical signal indicating only three states of pressure inside a duct or chamber containing gas; in particular, a first of said gas pressure states corresponds to pressure values inside said duct or chamber substantially equal to the pressure outside, a second of said pressure states corresponds to pressure values inside of said duct or said chamber higher than the external pressure and a third of said gas pressure states correspond to pressure values inside said duct or said chamber lower than the external pressure.

This detector may comprise a typically electromechanical device suitable for generating at least one electrical signal indicating only two or three gas pressure states and which comprises an element capable of moving under the action of the gas pressure and capable of assuming only two or three operating conditions.

One or two of the operating conditions of the mobile element may correspond to one or two predetermined positions; in the example of Fig.5 there is only one predetermined position while in the example of Fig.6 there are two predetermined positions.

As in the examples of Fig.5 and Fig.6, one of the operating conditions can correspond to a set of contiguous positions.

Such a gas detector can be used with advantage in an appliance according to the present invention and, in particular, in a gas distribution block of the appliance.

This gas distribution block is equipped with a gas inlet and a plurality of gas outlets; moreover, a plurality of automatic valves are respectively associated with the plurality of gas outlets; finally, a gas detector is mounted or integrated in the block, in particular associated with a manifold duct of the block.

For the purposes of the present invention, the most effective automatic valves are those of the piezoelectric type, that is, those which include at least one shutter associated respectively with an output of the valve and at least one piezoelectric element electrically controlled to move the shutter. A plurality of gas flow detectors may further be associated respectively with the plurality of gas outlets.

This component, ie the gas distribution block, is very compact and fully self-diagnosing, even automatically.

It is worth clarifying that in a household appliance according to the present invention it is also possible to use more than one gas distribution block as defined above; for example, it is possible to connect two gas distribution blocks in series and use one for the hob and one for the oven. In this case, one of the gas distribution blocks according to the present invention can be further equipped with at least one free gas outlet not associated with an automatic valve.

The present invention has been described with reference to particular embodiment examples, but it is clear that numerous variants of the present invention are possible in the light of the knowledge of those skilled in the art and that said variants all fall within the scope defined by the appended claims. .

Claims (38)

CLAIMS 1. Gas cooking appliance equipped with a gas connection (AG) and one or more gas burners (B1, B2, B3, B4), comprising: - an automatic general valve (VG) having an inlet associated with said connection (AG), - one or more individual automatic valves (V1, V2, V3, V4) having outputs associated respectively with said one or more burners (B1, B2, B3, B4), and - a conduit (TU) connecting the valve outlet general (VG) at the inlets of said one or more individual valves (V1, V2, V3, V4), characterized by the fact of including an electronic safety system (EL) capable of detecting anomalies and / or faults such as to cause gas flow unwanted at least through said general valve (VG). 2. Electric household appliance according to claim 1, wherein said gas burners (B1, B2, B3, B4) are two, three, four, five, six or seven. 3. Household appliance according to claim 1 or 2, characterized in that it comprises a gas flow detector (RG) placed downstream or upstream of said general valve (VG) in such a way as to detect gas flow through said general valve (VG ). 4. Household appliance according to claim 3, characterized in that said gas flow detector (RG) is placed in such a way as to detect gas flow through any one of said one or more individual valves (V1, V2, V3, V4) . 5. Household appliance according to claim 4, characterized in that said gas flow detector (RG) is placed along said duct (TU). 6. Household appliance according to claim 2 or 3 or 4, wherein said gas flow detector (RG) is associated, in particular applied or integrated, to the inlet, inside or outlet of said general valve (VG) . 7. Household appliance according to claim 4, wherein said one or more individual valves (V1, V2, V3, V4) are associated, in particular applied or integrated, to a single gas distribution block (AS) having a gas inlet and at least two gas outlets, characterized in that said gas flow detector (RG) is associated, in particular applied or integrated, with the inlet or inside said block (AS). 8. Household appliance according to one of the preceding claims, characterized in that said electronic safety system (EL) is further adapted to detect anomalies and / or failures such as to cause unwanted gas flow through each of said one or more individual valves (V1, V2, V3, V4). 9. Appliance according to claim 8, characterized in that it comprises at least one gas flow detector (R1, R2, R3, R4) placed downstream or upstream respectively of at least one of said one or more individual valves (V1, V2, V3, V4) in such a way as to detect gas flow through said at least one individual valve (V1, V2, V3, V4). 10. Household appliance according to claim 9, wherein said detector (R1, R2, R3, R4) is associated, in particular applied or integrated, to the inlet, inside or outlet of said at least one individual valve (V1, V2, V3, V4). 11. Household appliance according to any one of the preceding claims, in which said general valve (VG) has only a first and a second operating conditions, said first operating condition corresponding to a condition of total opening and said second operating condition corresponding to a condition of total closure. 12. Household appliance according to any one of the preceding claims, wherein said general valve (VG) is of the electromagnetic type. 13. Household appliance according to any one of the preceding claims, characterized in that said safety system (EL) is able to generate an alarm signal, in particular an acoustic signal and / or a visual signal in the event of said anomalies and / or faults . 14. Appliance according to any of the preceding claims, characterized in that said safety system (EL) is designed to prevent the appliance from functioning in the event of said anomalies and / or failures. 15. Household appliance according to any one of the preceding claims, characterized in that said safety system (EL) is able to close said general valve (VG) in the event of said anomalies and / or failures. 16. Household appliance according to any one of the preceding claims, characterized in that it comprises at least one gas flow detector comprising a device capable of generating at least one electrical signal indicating only two gas pressure states and an electronic system capable of repeatedly reading said at least an electrical signal and to obtain information indicating only two gas flow states, in particular the substantial absence of gas flow and the substantial presence of gas flow. 17. Household appliance according to any one of the preceding claims, characterized in that it comprises at least one gas flow detector comprising a device capable of generating at least one electrical signal indicating only three gas pressure states and an electronic system capable of repeatedly reading said at least an electrical signal and to obtain information indicating only three gas flow states, in particular the substantial absence of gas flow and the substantial presence of gas flow in a first direction and the substantial presence of gas flow in a second direction. 18. Household appliance according to claim 16 or 17, characterized in that said device comprises an element able to move by action of the gas pressure and able to assume two or three operating conditions. 19. Household appliance according to claim 18, characterized in that one or two of said operating conditions of said movable element correspond to one or two predetermined positions. 20. Household appliance according to claim 18 or 19, characterized in that one of said operating conditions corresponds to a set of contiguous positions. 21. Household appliance according to any one of the preceding claims, characterized in that it comprises at least one gas flow detector capable of generating an electrical signal indicating only two gas flow states, in particular the substantial absence of gas flow and the substantial presence of gas flow. 22. Household appliance according to any one of the preceding claims, characterized in that it comprises at least one gas flow detector capable of generating an electrical signal linked to the pressure difference, in particular the pressure detected in a first direction and the pressure detected in a second direction substantially perpendicular to said first direction. 23. Household appliance according to any one of the preceding claims, characterized in that it comprises at least one gas flow detector capable of generating an electrical signal linked to the displacement or position of an adjustment member of at least one corresponding valve. 24. Household appliance according to one of the preceding claims, comprising an electronic safety system (EL) capable of carrying out repeatedly and / or cyclically at least one procedure to verify the correct operation of said general valve (VG) and / or of said one or more valves individual (V1, V2, V3, V4). 25. Household appliance according to claim 24, in which a verification procedure is carried out at each closing of at least one of said one or more individual valves (V1, V2, V3, V4). 26. Household appliance according to claim 24 or 25, in which a verification procedure is carried out at each closure of said general valve (VG). 27. Household appliance according to claim 24 or 25 or 26, in which a verification procedure is carried out at each opening of said general valve (VG). 28. Household appliance according to any one of claims 24 to 27, wherein said at least one verification procedure is carried out by detecting the pressure and / or the pressure variation in said duct (TU). 29. Household appliance according to any one of the preceding claims, characterized in that it is a hob for a kitchen or an oven for a kitchen. 30. Gas detector (R) characterized in that it is adapted to generate at least one electrical signal indicating only two or three gas pressure states. 31. Gas detector (R) according to claim 30, characterized in that a first of said gas pressure states corresponds to pressure values substantially equal to the atmospheric pressure, a second of said gas pressure states corresponds to values of pressure higher than atmospheric pressure, one third of said gas pressure states correspond to pressure values lower than atmospheric pressure. 32. Gas detector (R) according to claim 30 or 31, characterized in that it comprises a device capable of generating at least one electrical signal indicating only two or three gas pressure states and that said device comprises an element capable of moving to action of gas pressure and able to assume only two or three operating conditions. 33. Gas detector (R) according to claim 32, characterized in that one or two of said operating conditions of said movable element correspond to one or two predetermined positions. 34. Gas detector (R) according to claim 32 or 33, characterized in that one of said operating conditions corresponds to a set of contiguous positions. 35. Gas detector (R) according to any one of claims 30 to 34, characterized in that it is used in a gas cooking appliance according to one of claims 1 to 29. 36. Gas distribution block (AS) having a gas inlet and a plurality of gas outlets, characterized in that it comprises a plurality of automatic valves associated respectively with said plurality of gas outlets and a gas detector according to any one of the claims 30 to 35. 37. Block according to claim 36, characterized in that it is used in a gas cooking appliance according to one of claims 1 to 29. 38. Gas cooking appliance, gas flow detector and automatic gas valve according to the innovative teachings of the present description and the annexed drawings which refer to preferred and advantageous embodiments.