Magnet-thermocouple system for fail-safe supply of gas to burners or the like

Abstract

Magnet-thermocouple for the fail-safe safety supply of gas to burners or the like, in particular of fail-safe safety control for domestic cooking devices, comprises: at least one gas burner, which gas burner is connected to a gas supply source by flame-regulating means and by means of a safety valve driven by a flame presence sensor consisting of a thermocouple, said safety valve having an open condition, wherein said supply source supplied said burner, and a closed condition, wherein the gas passage is interrupted and wherein the thermocouple, in the presence of a flame, generates an electrical signal constituting the drive signal for the passage of said safety valve from an open condition to a closed condition, and vice-versa, of said safety valve, whereas a further drive signal generator and power supply of said safety valve is provided, for the temporary and alternative supply of the safety valve during the flame ignition step heating the thermocouple, to the temperature generating the drive signal. According to the invention, the signal generator and power supply comprise power limiters to limit the signal generated and an automatic deactivating unit whenever the power supply is overloaded for a predefined amount of time, the power necessary for the drive signal of the safety valve being greater than the one determined by the limiters.

Claims

1. A magnet-thermocouple system for a positive safety supply of gas to burners for a positive safety control of domestic cooking devices, comprising: a gas burner connected to a gas supply source with a flame-regulating system and with a safety valve driven by a flame presence sensor comprising a thermocouple, wherein said safety valve has an open condition, wherein said supply source supplies said burner, and a closed condition, wherein passage of gas is interrupted, wherein the thermocouple, when a flame is present, generates an electrical signal constituting a drive signal that switches said safety valve from the open condition to the closed condition, and vice versa, further comprising an additional power supply of a drive signal of said safety valve, for a temporary and alternative supply of the safety valve during flame ignition that heats the thermocouple, to a temperature generating the drive signal, wherein the additional power supply of the drive signal comprises power limiters to limit the generated signal and an automatic deactivating unit when the power supply is overloaded for a predefined amount of time, the power necessary for the drive signal of the safety valve being greater than the one determined by the limiters, and wherein the power supply of the drive signal is provided with thermal safety elements against overheating in an overload condition, when more energy is requested than a predefined level of deliverable energy.

2. The system according to claim 1, wherein the power supply of the drive signal is of a switching type.

3. The system according to claim 1, further comprising a manual drive member controlling the power supply of the drive signal of the safety valve, the manual drive member activating said power supply to generate and supply the drive signal of the safety valve when the gas is supplied to the burner.

4. The system according to claim 1, further comprising an automatic drive member of the power supply of the drive signal of the safety valve, the automatic drive member activating and deactivating the power supply of the drive signal of the safety valve depending on a request signal generated based on a drive software.

5. The system according to claim 3, further comprising an ignition device comprising an ignition electrode and an electrical power supply thereof, which send current pulses to said ignition electrode to generate a spark at nozzles of said burner, said manual drive member also simultaneously activating the power supply of the drive signal to said ignition electrode.

6. The system according to claim 1, wherein the power supply is configured to generate drive signals of the safety valve with different polarizations so as to temporarily drive said safety valve to an open gas passage condition for an activation period of the thermocouple to transmit a flame presence signal and to drive, with a reversed polarity drive signal, a closing of the safety valve in a flame presence condition, compensating the drive signal of the safety valve generated by said thermocouple.

7. The system according to claim 1, further comprising one or more electromechanical, electronic, analog, and/or digital timers, which are adapted to be set for programming a turn off and/or on of the flame beyond an amount of time programmed by a user or after a predefined amount of ignition time with a safety function, or to activate or deactivate the power supply to the safety valve and/or an ignition electrode, respectively of a closing or opening drive signal of the safety valve and of the supply signal of the ignition electrode.

8. The system according to claim 7, wherein the power supply is provided in combination with luminous and/or acoustic signaling means of an operating condition of the safety valve and/or the burner.

9. The system according to claim 8, wherein said signaling means are provided in combination with message transmission means of the operating condition that transmit to a remote reception unit, said remote reception unit being provided with remote generation and transmission means of drive signals of the power supply of the drive signals of the safety valve and/or the ignition electrode.

10. The system according to claim 1, further comprising a visual or acoustic signaling unit and/or a unit transmitting operational information messages to remote devices, optionally portable, that inform of a flame presence condition.

11. The system according to claim 1, further comprising a flame detection system that comprises ionization sensors or operates by way of thermocouple voltage or by way of magnetic detection of thermocouple current.

12. The system according to claim 1, further comprising one or more flame detection devices selected from the group consisting of optical, thermal and magnetic sensor devices.

13. The system according to claim 1, further comprising a centralized generator/power supply for a drive signal shared between one or more safety valves of a plurality of safety valves, each of which is coupled to one of a plurality of gas feed taps to a different burner, and a control unit that controls the power supply of the drive signal of the respective safety valve for one or more of the different taps of said plurality of taps.

14. The system according to claim 1, further comprising a plurality of taps, one or more of said taps having an own safety valve, each tap being coupled to a different burner of a plurality of burners, said system being provided for at least one or more of said burners and composed of three modules, of which a first module includes the power supply of the drive signal of the safety valves of the taps of said plurality of burners, wherein the drive signal is shared by all of said safety valves, a basic drive module that commands the power supply of the drive signal of the safety valve of the taps of said plurality of burners and/or an ignition electrode, and a separate module for each tap of said one or more burners that comprises activation/deactivation timers of a respective burner.

15. A cooking device comprising one or more burners, each of which is supplied with a gas mixture having a flow is regulated by a tap, and each of which is provided with a flame presence detection device, wherein each tap is provided with a safety valve coupled to a respective burner, and wherein each safety valve is comprised within a magnet-thermocouple system according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and further characteristics and advantages of the present invention will become clearer in the following description of some exemplary embodiments depicted in the accompanying drawings, in which:

(2) FIG. 1 shows a block diagram of an example of a system according to the state of the art.

(3) FIG. 2 shows a block diagram of a first embodiment according to the present invention.

(4) FIG. 3 shows an operational block diagram of an embodiment according to the present invention.

(5) FIGS. 4A and 4B, and 5A and 5B, show the detailed circuit diagram of an embodiment according to the present invention, wherein FIG. 4A and respectively 5A is the left part of the circuit and FIG. 4B and respectively 5B is the right part.

(6) FIG. 6 shows an embodiment variation of the embodiment in FIG. 3, wherein the system operates in combination with a plurality of burners, 1, 2, . . . , n, each with a thermocouple and gas flow regulation tap provided with a safety valve.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(7) With reference to FIG. 2, in an embodiment of the present invention, at the design level, the circuit is subdivided into two parts, of which a first one is constituted by the power supply circuit and a second one is constituted by the load drive circuit. Those two parts are shown integrated in a single box 200 denoted as drive circuitry. The load 220 is constituted by the servocontrol magnet coil of the safety valve, which assumes a stable closed condition preventing the passage of gas to the burner is prevented, and which is mechanically and automatically urged in the absence of an electrical excitation signal of the magnet. Whenever this signal is present, the magnet determines the displacement of the shutter of the safety valve in an open gas passage condition, against the action of the mechanical means that urge said shutter in a stable way in the closed condition, that is, against the seat of the valve. The load drive circuit 220 works with a preselected quantity of energy. This preselected quantity, which is supplied to the load in order to determine the switching of the safety valve to the open condition, is greater than the quantity that can be supplied from the power supply assembly arranged upstream of the drive circuit.

(8) As depicted in FIG. 2, the drive circuitry 200 can be combined with a manually activated control of the activation of the generation and power supply of the drive signal to the safety valve. This manually activated control can be a switch, a button, a knob to activate the regulation tap of the gas flow to the burner and is provided with a drive movement, and the drive generated by the manually activated member is transformed into an electric signal provided to the drive circuitry 200 by a suitable detection board detecting the activation of the manual control denoted by 210.

(9) In alternative or in combination with the manually activated control with the relative detection board 210, an automatic drive unit may be provided operating, for example, by means of one or more programmable timers 240. These timers allow setting the turn on and turn off times of the burner combined with the corresponding safety valve, due to the activation of the power supply generator of the drive signal and of the drive unit, which are depicted as integrated in the drive circuitry 200.

(10) Other operative units may be linked to control the drive circuitry 200 in order to drive the safety valve to the open gas passage condition or the closed condition of said passage.

(11) In the illustrated embodiment, the control board of a suction hood 230 is depicted as an example. This example must not be considered limiting with regard to further possible examples that can be provided in alternative or in combination with the same.

(12) As mentioned, an additional activation board (not shown) of a flame ignition electrode may be provided at the burner.

(13) The power supply circuit was designed to guarantee the nominal performances under the worst operating conditions (maximum load and temperature). The energy required is beyond the normal operating value guaranteed during the load driving step for the turning off or on. The maximum time period during which this energy is available is linked to the operating temperature of the device, to the dissipative areas and the size of the inductive part.

(14) 250 denotes a thermocouple or other flame detecting system generating or driving the generation of a drive signal to open the safety valve 220 in the presence of a flame.

(15) FIG. 3 shows an operational block diagram of an exemplary embodiment according to the present invention and which makes the conceptual subdivision of the drive circuitry of the preceding example into two parts even clearer.

(16) The drive unit is essentially constituted by an electronic control 300 that performs a control logic. The control logic can be constituted by software in which the instructions for a processing unit are encoded and which instructions configure said processing unit to carry out the operational steps of the system.

(17) The control logic can be in the form of an executable software or firmware, or can essentially be implemented, in a fixed way, in a hardware specifically constructed and configured to execute the operations defined by the control logic itself.

(18) The power supply 310 provides energy to a current generator 320, which generates the drive signal of the safety valve, and the control logic manages the methods through which the signal is transmitted 370 to the safety valve in order to control it during the opening and closing, in particular in the start-up step of the thermocouple at the time of a flame ignition or in the controlling step of the automatic and programmed turn-off function of the burner on the basis of the settings performed in the various timers.

(19) A section 360 activates the generator output under the control of the control logic 300 and provides the drive signal to the safety valve, denoted by 220 in FIG. 2 and herein represented by the connection 370.

(20) The control logic 300 manages the interfaces with the other units, such as one or more timers, the thermocouple, the flame igniting electrode, the sensor activating the suction hood and the like.

(21) The interface 330 is facing the connection of the control logic 300 to the various peripheral units, such as the timers, the ignition electrode, the suction hood and others, whereas the blocks 340 and 350 separately denote the operational connection to the thermocouple. In this case, the block 350 for reading the signal of the thermocouple acts both directly on the safety valve 220 and indirectly through the control logic 300.

(22) FIGS. 4A and 4B, and 5A and 5B, show a more detailed exemplary embodiment of the power supply generator according to the invention.

(23) The power supply circuit is made galvanically isolated and is constituted by a switching power supply for high temperatures (FIGS. 4A and 4B). This type of power supply is composed of a control logic, a bulk capacitor denoted by 1, and a transformer denoted by 5, 5A, 5B in FIGS. 4A and 4B. The transformer guarantees the galvanic isolation between the drive stage and stage connected to the load. The value of the primary inductance of the transformer, denoted by 5B, determines the maximum current circulating in the transformer and, consequently, the maximum power that the power supply circuit can deliver. The control logic manages a limiting resistor for a further reduction of the current circulating in the primary, named R41 and denoted by 2 in the scheme of FIGS. 4A and 4B. This allows monitoring and limiting the maximum current of the transformer primary.

(24) The correct sizing of the transformer primary, denoted by 5B, allows greater efficiency of the entire power supply, holding down the temperatures as well as limiting the maximum current available to the load.

(25) The power supply circuit controls and regulates the output voltage, for the operations of the system, the power supply generates two output voltages connected to one another and to the connection point of these outputs for the ground reference connection denoted by 8.

(26) In order to improve the power supply to the safety valve of the gas, the output circuit, which is connected to the power supply, limits the maximum power by different methods:

(27) through limitation hardware

(28) through software for limiting the power available.

(29) With these operating methods, it is possible to guarantee a minimum quantity of drive energy without causing the intervention of the protections. In case of abnormal operations, with the system supplying the load in an incorrect way, the protections are automatically activated and the entire system is turned off.

(30) Two types of operations are described in detail here below.

(31) Limitation Operation with the Hardware Method:

(32) An output current, both positive and negative with respect to the constant ground, is generated by means of a circuit, as denoted by 6 in FIGS. 5A and 5B. This output current, together with the constant supply voltage, and which is regulated by the power supply denoted by 4 in FIGS. 4A and 4B, causes a constant-power supply of the coil of the safety valve. The limitations of power provided by the power supply circuit and that are derived from the limited voltage of the primary and the voltage of the secondary stabilized by the square wave generator 6 (in FIGS. 5A and 5B) with constant current, define the operating limitations of the circuit in terms of hardware.

(33) Whenever the system is provided for a unit with more burners, or in the presence of a device with a plurality of burners of which at least one for each burner, by means of a further assembly of components, the components of this assembly are replicated for each burner, as denoted by 7 in FIGS. 5A and 5B. In this case, it is possible to select one or more burners to which the drive signal can be applied or to read the current of the thermocouple according to one or more known methods of the state of the art.

(34) Limitation Operation with the Software Method:

(35) By controlling the signals of the generator, activated and deactivated at constant and controlled time intervals, a quantity of energy is transferred to the load to allow it to be driven without overloading the power supply and without turning it off. This drive system is possible due to the operations of the safety valves, which remain open by means of a magnetic hook, which, by nature, has a magnetic hysteresis, therefore the magnetic field maintaining the valve open is equal to the average value of the current in the moment the circuit is supplying and the value weighed, whenever not supplied, as a function of the time and percentages of the two situations.

(36) In an embodiment, the weighing is carried out according to the following function:
(Energy on)*% (time on))+(Energy off)*% (time off)).

(37) To summarize the above disclosure, by means of the hardware part of the board, a supply may be generated with defined power of the safety valve and thermocouple assembly, and by means of a timed management, via software, it is possible to select the value of the energy to be transferred to the safety valve so that to be able to regulate the average value thereof.

(38) In addition to the preceding disclosure, the system is adapted to generate, with the same concept, both positive and negative signals with respect to the 0 plane of the gas valve, thus providing, depending on the polarity generated, for keeping the safety valve open or forcing it to close.

(39) FIG. 6 shows an embodiment, in which the system is provided in combination with a plurality of burners, each of which is supplied by a tap for regulating the gas flow and which comprises a safety valve, each of the burners being provided with at least one flame presence device, in particular with a thermocouple.

(40) In the scheme of FIG. 6, the individual valves combined with the burners 1, 2, . . . , n are denoted by 671, 672, 67n. Similarly, the thermocouples combined with each burner 1, 2, . . . , n are denoted by 651, 652, 65n.

(41) The power supply 610, the generator 620 and an activator of the outlet of the generator 660 are controlled, like in the example of FIG. 3, by the control logic 600.

(42) Similarly to the example in FIG. 3, there are connecting interfaces 630 to connect to one or more further units, such as a flame igniting spark plug, an operating sensor or an activation actuator of a suction hood and other peripheral units for example.

(43) According to a further characteristic, each of the embodiments illustrated can provide means for generating the indication signals relative to the operating conditions of the system. Whenever more burners are provided, it is possible to have dedicated and separate signaling devices for each burner. The signaling devices can be luminous or visual and/or acoustic.

(44) By providing a peripheral device constituted by a transmitting/receiving unit, for example by means of wireless or telephonic or other types of protocols, it is also possible to send the signals to remote units, such as remote control boards or portable devices for example, such as smartphones or similar.

(45) According to another embodiment, the remote devices according to one or more of the variants described can also be configured to operate like user interfaces for the inputting of activation commands and/or program data for turning actions on and/or off with respect to one or more burners in combination with the embodiment variation of the system allowing these operations and which is described above.

(46) According to another embodiment, flame detecting means may be provided that are different from simple thermocouples. These means can be provided in place of the thermocouples or in addition to them and they can be, for example, visual detecting means, and/or ionization means or means using other physical effects of a flame presence condition.