Patent Document

PRIORITY CLAIM 
     This application claims priority from European patent application No. 07425487.1, filed Jul. 31, 2007, which is incorporated herein by reference. 
     TECHNICAL FIELD 
     An embodiment of the present invention relates to an automatic device for the ignition and control of a gas apparatus equipped with at least one burner and with electrically controlled valve means for regulating the flow of gas from a main pipe towards a nozzle associated with said at least one burner. 
     The automatic device being supplied by at least one supply voltage provided by the electricity main and/or by battery means, being coupled to a ground terminal and comprising:
         a spark circuit suitable for generating a pilot flame upon receipt a start signal.       

     An embodiment of the present invention also relates to a driving method of an automatic device for the ignition and control of a gas apparatus. 
     An embodiment of the invention concerns, in particular but not exclusively, a device for gas apparatuses like for example fires, stoves and gas braziers and the following description refers to this field of application with the sole purpose of simplifying its explanation. 
     BACKGROUND 
     As known, gas fireplaces, gas stoves and gas braziers are ignited by an electromechanical ignition device, generally activated by a user, which allows the ignition of a pilot flame at a pilot burner as well as its supervision to ensure that the pilot flame acts as an ignition source for a burner of greater thermal power. 
     There are suitable valve means for regulating the gas coupled with the ignition device, arranged between the main pipe for the gas and the burners, which are subjected to a thermocouple. 
     The thermocouple, heated by the flame of the burner, electromechanically monitors the permanent ignition state of the flame. Therefore, possible flame extinction determines a cooling down of the thermocouple and, consequently, the closure of the gas supply to the burner. 
     In such apparatuses, it is easy to verify if the flame has been extinguished or lost, since it is generally due to a gust of air, a jump in the flue draft, a simple exhaustion of the gas, or similar anomalies. 
     Therefore, the flame is constantly monitored in the burner in order to avoid damage and dangerous gas leaks. The electromechanical monitoring, by thermocouple, although advantageous from various points of view, has the drawback that the gas supply is not shut off immediately, but occurs only after the cooling of the thermocouple itself. Therefore, there is a danger of the gas escaping without being burnt for a certain period of time before being turned off. 
     Moreover, during the initial flame ignition step, the user performs a direct manual action in the vicinity of the burner to keep the flame active for a time necessary to heat up the thermocouple. This manual action is risky for the user. 
     In order to avoid these drawbacks, in recent apparatuses the thermocouples are regulated by special devices that automatically check for the presence of a flame during the ignition step of the gas apparatuses. 
     Such automatic devices are also supplied by electricity main and by battery means or buffer batteries allowing the apparatuses on which they are installed to operate when the electricity main is not feeding. 
     Usually the apparatuses, like for example gas fires, are used at locations where there is not a constant supply of electrical power, but rather where the electrical supply varies unpredictably. 
     Automatic devices with thermocouples are substantially high-energy-consumption devices since they require a high current to maintain the main flow of gas, during the automatic ignition step, to support the flow of gas during the heating step of the thermocouple, and for possible restoring after a flame has been lost. 
     Therefore, due to the high power required, automatic devices with thermocouples, supplied by buffer batteries, have very low autonomy and are therefore not very efficient, often requiring continuous replacement of the batteries by the user. 
     This represents a limitation to use of such automatic devices in gas apparatuses. 
     SUMMARY 
     An embodiment of the present invention provides an automatic device for gas apparatuses, having structural and functional characteristics such as to overcome the limits and/or drawbacks with reference to devices realized according to the prior art. 
     Another embodiment of the present invention provides an automatic device with low energy consumption in order to dynamically bias the valve means. 
     An embodiment of the present invention is directed to an automatic device for the ignition and control of a gas apparatus comprising at least one burner for regulating the flow of gas from a main pipe towards a nozzle associated with said at least one burner;
         a spark circuit suitable for generating a pilot flame upon receipt a electric start signal;   electrically controlled valve means associated with said at least one burner;—at least one supply voltage provided by the electricity main and/or by battery means, to supply said automatic device   an electrical microprocessor unit in said automatic device to drive and to control said valve means and said spark circuit;   at least one actuator circuit activated by said electrical microprocessor unit through an activation signal having a pulse train to dynamically bias said valve means and to regulate its charge state according to the duty cycle of the pulse train.       

     An advantage of the automatic device according to an embodiment of the invention is that it is substantially a low-voltage device with low power consumption, with electrical and completely independent management in terms of the initial ignition step, in terms of the control of the valve means and for the supervision of the flame. Moreover, such a device, when there are anomalies, allows the completely automatic restoring of the device to be carried out quickly, or else allows it to be made safe. 
     Another embodiment of the present invention is directed to a method for driving an automatic device for the ignition and control of a gas apparatus equipped with at least one burner and including electrically controlled valve means for regulating the gas flow from a main pipe towards a nozzle associated with said at least one burner;
         said automatic device being supplied by at least one supply voltage provided by the electricity main and/or by battery means and being coupled to an ground terminal,   said method comprising the following steps:   initial automatic ignition phase activating a spark circuit upon receipt of a start signal to generate a flame in said at least one burner;   driving and controlling said valve means and said spark circuit through an electrical microprocessor unit;   activating at least one actuator circuit coupled to said valve means by means of an activation signal having a pulse train generated by said electrical microprocessor unit;   activating at least one actuator circuit coupled to said valve means by means of an activation signal generated by said electrical unit, said activation signal having a pulse train to dynamically charge said valve means for an activation time period defined by the duty cycle of the pulse train.       

     An advantage of the method for driving the automatic device according to an embodiment of the invention is its efficiency linked to the low energy consumption required and the completely electrical management in terms of the ignition step, for the flame control step and during the operation of the device; moreover, such a method, when there are anomalies, allows the automatic device to be automatically restored or be made safe quickly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Characteristics and advantages of the automatic device according to one or more embodiments of the present invention will be apparent from the following description of an embodiment thereof given by way of indicative and not limiting example with reference to the annexed drawings. 
         FIG. 1  schematically shows an apparatus of an automatic device for ignition and control, according to an embodiment of the invention. 
         FIG. 2  schematically shows a block diagram of the apparatus of  FIG. 1 . 
         FIG. 3  is a block diagram of the device according to an embodiment of the present invention. 
         FIGS. 4-15  show details of the blocks as shown in  FIG. 3 . 
         FIGS. 16-18  show an actuator circuit of the valve means, made according to and embodiment of the invention, in the various operating steps. 
         FIG. 19  shows a diagram with a time progression of an activation signal of the actuator circuit according to an embodiment of the present invention. 
         FIGS. 20-21  show a time reference circuit associated with an electrical unit and made according to an embodiment of the invention, in two operating steps. 
         FIG. 22  shows a diagram with time sequences of operating signal relative to the circuit of  FIG. 20 . 
         FIG. 23  illustrates a diagram with time progressions of operating signal relative to a flame detector made according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to such figures an automatic device made according to an embodiment of the present invention for the ignition and control of a gas apparatus  1  is globally and schematically indicated with  10 . 
     The gas apparatus  1  is in particular a gas fireplace, schematically represented in  FIG. 1 , but the automatic device  10  can be used in other apparatuses like for example gas stoves and gas braziers and similar. 
     The gas apparatus  1  is equipped with a pilot burner  11  and with a main burner  12  and suitable electrically controlled valve means  7 , for regulating the flow of gas from a main pipe  28  for the gas towards a first nozzle  8 , coupled with the pilot burner  11  and to a second nozzle  13 , coupled with the main burner  12 , respectively. 
     The pilot burner  11  and the main burner  12  are coupled in the usual way, so that the flame at the pilot burner  11  can act as ignition source for the gas released by the nozzle  13  to the main burner  12 . A supply voltage provided by electricity main  2 , through a transformer  3 , and by battery pack  4  supplies the automatic device  10 ; the automatic device  10  is coupled through a ground terminal  59  to a constant reference voltage GND that in the present embodiment is a ground voltage. 
     Moreover, the valve means  7  are supplied by a supply voltage and are of the type with the valve normally closed. 
     In particular, the valve means  7  comprise a first solenoid  17 , which actuates a first shutter associated with the first nozzle  8  so that when the solenoid is crossed by an electric current the first shutter opens allowing the gas to flow, whereas, when the solenoid is not crossed by an electric current the shutter closes blocking the flow of gas. 
     Similarly, a second solenoid  18  actuates a second shutter associated with the second nozzle  13 . 
     The automatic device  10  comprises a spark circuit  80  suitable for generating a flame on the pilot burner  11 , close to the first nozzle  8 , upon receipt of a start signal Start. 
     According to an embodiment of the present invention, the automatic device  10  comprises an electrical microprocessor unit  5  that actuates and electrically controls both the spark circuit  80  and such valve means  7 , so as to uniformly and totally burn all of the gas put out exploiting to the highest degree the thermal value as well as in complete safety. 
     Advantageously, according to an embodiment of the present invention the valve means  7  are activated by the electrical unit  5  and are coupled to the ground terminal  59 . 
     The automatic device  10 , as illustrated in  FIG. 4 , comprises a first actuator circuit  40  and a second actuator circuit  45 , structurally similar, dynamically activated by the electrical unit  5 , through a first activation signal  21  and a second activation signal  22 , respectively. 
     The first activation signal  21  and the second activation signal  22  are signals having a pulse train with a predetermined charge factor or duty cycle. 
     Such actuator circuits  40 ,  45  are suitable for dynamically polarizing the valve means  7  to regulate its charge state according to the duty cycle of the pulse train. 
     In particular, according to an embodiment of the present invention, the automatic device  10  and in particular the electrical unit  5  is substantially a circuit operating at low voltage that dynamically drives such valve means  7 , with a low power consumption and a substantial saving of energy. 
     The automatic device  10  is supplied by:
         the electricity main  2  that supplies a voltage VAC to the transformer rectifier  3 , which through a first terminal  16  provides a first supply voltage VDC; and   battery pack  4  that supply a second supply voltage VBB through a second terminal  20 .       

     According to an embodiment, the transformer rectifier  3  comprises a Graetz bridge rectifier or else a modern switching voltage regulator, for example of the Step-Down or Buck type. 
     A remote control panel  6  allows the electrical unit  5  to be activated upon receipt of the start signal Start. The start signal Start is transmitted through a set of terminals  27  and can consist of a protocol, in the form of an encoded signal, or else the reading of a switch or contact open and closed state. 
     According to an embodiment, the remote control panel  6  comprises a pair of switches coupled to the array of terminals  27 . 
     A diagnostic circuit  14  interacts with the electrical unit  5  through suitable connection terminals  15  and allows the user to keep the automatic device  10  constantly under remote observation, allowing possible anomalies to be diagnosed. 
     According to an embodiment of the present invention, in the case of anomalies the automatic device  10  acts autonomously intervening to restore its functionality or to place it under safe conditions. 
     The control panel  6  and the diagnostic circuit  14  could in some cases be incorporated directly in the electrical unit  5 . 
     In particular, the electrical unit  5  comprises a programmable microcontroller  30  capable of storing a management program that analyzes the received signals, generating suitable signals for the operation and for the safety of the automatic device  10  itself. 
     The automatic device  10  also comprises a selector  50  that is supplied in input by the first supply voltage VDC and by the second supply voltage VBB to supply in output a third constant voltage VCC_Pos, which is substantially the greater of the input supply voltages. 
     As shall be specified hereafter, the selector  50  uses the battery pack  4  as a buffer battery both in the case of a total lack of the first supply voltage VDC, and in the case in which the electricity main  2  supplies sporadic low voltages compared to a nominal voltage. 
     In particular, the selector  50  feeds an enable circuit  46 , a regulator circuit  60  and a high voltage generator circuit  85 . 
     The enable circuit  46  provides in output a fourth voltage VCC which is a voltage substantially translated in level compared to the third voltage VCC_Pos and suitable for feeding the first  40  and the second actuator circuit  45  and defined arranged control peripherals. 
     The regulation circuit  60  carries out a first filtering for possible over voltages in the third supply voltage VCC_Pos supplying in output a substantially stabilised fifth supply voltage VDD suitable for feeding the electrical unit  5 . 
     According to an embodiment of the present invention, as highlighted in  FIG. 4 , the first actuator circuit  40  and the second actuator circuit  45  are supplied by the fourth supply voltage VCC respectively through a first supply terminal  47  and a second supply terminal  48  and they are also coupled to the ground terminal  59 . Moreover, they are activated by the first activation signal  21  and by the second activation signal  22  received, respectively, at a first input terminal  23  and at a second input terminal  24 . 
     The first activation signal  21  and the second activation signal  22  having a pulse train have regular pulses of rectangular wave shape with a particular and predetermined charge factor or duty cycle, so as to dynamically activate the valve means  7  coupled to a respective output terminal  34 ,  35 . 
     In particular, according to an embodiment, the first actuator circuit  40  comprises a first inductance L 1 , arranged between the first supply terminal  47  and an inner node A, a first capacitance C 1 , arranged between the inner node A and an output node E, which is coupled with the ground terminal  59  through a first diode D 1  that, for greater efficiency, is of the Schottky type. 
     A first resistance R 33  is also arranged between the output node E and the first output terminal  34 . 
     A first switch Q 1  is arranged between the inner node A and the ground terminal  59  and is suitably activated at a command terminal G by the first activation signal  21 . 
     The first switch Q 1  can be a Fet or Mosfet transistor or else a BJT transistor. 
     A first resistive divider R 7 -R 8  is coupled with the first input terminal  23  and is coupled to the ground terminal  59  and allows the voltage of the first activation signal  21  to be adjusted in a predetermined way. 
     Furthermore, the first actuator circuit  40  comprises a first filtering element F 1  arranged between the inner node A and the ground terminal  59  capable of filtering the signal present at the inner node A. In particular, the first filtering element F 1  comprises, coupled in series, a resistance R 4  coupled to the inner node A and to a capacitance C 9 . 
     In an embodiment, at the first actuator circuit  40  a Zener diode DZ 3  is arranged between the inner node B and the command terminal G of the first switch Q 1 , to make a further protection of the first actuator circuit  40  against over voltages that could reach the fourth supply voltage VCC through the first supply terminal  47 . 
     The first impulsive activation signal  21 , based upon the provided duty cycle, has an activation time period T ON  and a deactivation time period T OFF  and dynamically biases the first inductance L 1  and the first capacitance C 1 . In particular, the first actuator circuit  40  absorbs electrical energy discontinuously from the fourth supply voltage VCC only during the activation time period T ON  and returns it by taking a substantially continuous current from such valve means  7 . 
     The first activation signal  21  generates a potential at the output node E that is kept below the potentials of the other nodes of the first actuator circuit  40 . In particular, the potential of the output node E is less than the ground voltage GND of the ground terminal  59 . 
     The activation time period T ON  of the first activation signal  21  is substantially less than the deactivation time period T OFF . 
     In other words, unlike the prior art, the first actuator circuit  40 :
         during the activation time period T ON , receives a charge current, i.e. from the first solenoid  17 , keeping the flow of gas to the first burner  11  open;   during the deactivation time period T OFF , the output node E is coupled to the ground terminal  59  through the first diode D 1  and thus also the first solenoid  17  and the first solenoid  17  as a effect of its own inductance is crossed by a current still coming out towards the output terminal E, keeping the flow of gas to the first burner  11  open.       

     This allows, in particular, the energy required by the first actuator circuit  40  during its operation to been substantially reduced with a substantial reduction of the power absorbed. 
     With reference to  FIG. 19 , the duty cycle of the first activation signal  21  is defined by the formula:
 
duty cycle= T   ON /( T   ON   +T   OFF )
 
     where T ON  is the activation time period and T OFF  is the deactivation time period. 
     With reference to  FIGS. 16-18 , the operation of the first actuator circuit  40  is analyzed in particular. 
       FIG. 16  shows the first actuator circuit  40  in a rest state, in which the fourth supply voltage VCC is present whereas the first activation signal  21  is absent, i.e. the electrical unit  5  enables the enable circuit  46  but still does not command the first actuator circuit  40 . 
     In this case, the first switch Q 1  is in open state and the first capacitance C 1  is charged at the fourth supply voltage VCC through a current that, from the first supply terminal  47  slips through the first inductance L 1 , the first capacitance C 1  and the first diode D 1  towards the ground terminal  59 . 
       FIGS. 17 and 18  illustrate the first actuator circuit  40  activated by the first activation signal  21 , in a first and a second operative condition, respectively. 
     In particular, in the first operative condition, the first activation signal  21  is active for the activation time period T ON  and the first switch Q 1  closes connecting the inner node A to the ground terminal  59 . The first inductance L 1  accumulates inductive energy, whereas the first capacitance C 1  discharges absorbing current from the first solenoid  17  whilst the first diode D 1  is electrically blocked. 
     In such a first operative condition, for the brief activation time period T ON , the first actuator circuit  40  absorbs a current from the first solenoid  17  and in particular a current slips from the charge towards the inner node A making the voltage at the output node E negative with respect to the reference voltage GND present at the ground terminal  59 . 
     In such a first operative condition, the first solenoid  17 , crossed by the electric current, allows the first shutter to open allowing the gas to flow to the pilot burner  11 , whereas the power required by the first actuator circuit  40  is given by the energy accumulated by the first inductance L 1  during the brief activation time period T ON . 
     In the second operative condition, the first switch Q 1  is kept open for the passive time period T OFF . The first inductance L 1  discharges the inductive energy accumulated during the activation time period T ON , recharging the first capacitance C 1  through the first diode D 1  which is also brought into conduction and a current continues to flow from the first solenoid  17  to the first diode D 1 . 
     Therefore, also during the deactivation time period T OFF , the output node E is kept at a negative voltage with respect to the reference voltage GND of the ground terminal  59 . The first solenoid  17 , crossed by substantially continuous current, allows the first shutter to be kept open allowing the gas to flow to the pilot burner  11  without any power requirement from the supply and therefore with a substantial saving of energy. 
     Substantially, therefore, the first actuator circuit  40  activated by the first activation signal  21  keeps the transfer of energy from the to the charge operative with a transfer factor that depends upon the duty cycle of the first activation signal  21 . 
     Furthermore, when the first activation signal  21  is deactivated the first switch Q 1  is kept open and the first actuator circuit  40  is taken back into rest state. 
     Moreover, according to an embodiment of the present invention, the first activation signal  21  has the duty cycle regulated so that the current that crosses the first solenoid  17  for each activation time period T ON  and for each deactivation time period T OFF , is greater than a minimum opening current suitable for keeping the first shutter open making the gas flow to the pilot burner  11 . 
     According to an embodiment of the present invention, the electrical unit  5  modulates the duty cycle of the first activation signal  21  according to some parameters, like for example:
         value of the fifth supply voltage VCC;   value of the minimum opening current of the first solenoid  17 ;   value of a temperature of the first solenoid  17 , as shall become clearer hereafter.       

     In particular, there is substantially a retroaction between the first actuator circuit  40  and the electrical unit  5 . A value of the measured current I_Measure, proportional to the current present at the first output terminal  34 , is detected through a detection terminal  31  coupled to the first output node E. 
     Such a value is suitably processed by the electrical unit  5  based upon suitable reference values stored and possible corrective compensations of the duty cycle of the first activation signal  21  can be foreseen, in relation to the specific parameters of the first solenoid  17 , indicated above. This allows a substantial saving of energy at the automatic circuit  10 . 
     Moreover, in the case in which the first solenoid  17  undergoes variations due to the environment temperature that can change the electrical characteristics, for example such as to generate undesired deactivation thereof, the value of the measured current I_Measure undergoes variations which are intercepted by the electrical unit  5  and are compensated correctively by varying the duty cycle of the first activation signal  21 . 
     Similarly, as highlighted in  FIG. 4 , the second actuator circuit  45  comprises a second inductance L 2  arranged between the second supply terminal  48  and an inner node A′, a second capacitance C 2  arranged between the inner node A′ and an output node E′ which is coupled with the ground terminal  59  through a second Schottky diode D 2 . A second resistance R 72  is coupled in series between the output node E′ and through a second output terminal  35  to the charge or else to the second solenoid  18 . 
     A second switch Q 3 , arranged between the inner node A′ and the ground terminal  59 , is driven dynamically by the second activation signal  22  which is suitably regulated in voltage by a second divider R 12 -R 14 . 
     In an embodiment, the second actuator circuit  45  has a Zener diode DZ 6  that is arranged between the inner node B′ and the command terminal G′ of the second switch Q 3 , to make a further protection against excessive voltages that could reach the fourth supply voltage VCC through the terminal  48 . 
     The second impulsive activation signal  22 , based upon the provided duty cycle, regulates a charge time T ON′  and a discharging time T OFF′  of the second capacitance C 2  keeping the second output node E′ at a potential that is less than any potential present at the other nodes of the second actuator circuit  45  and in particular of the voltage at the ground terminal  59 . 
     A second filtering element F 2  is arranged between the inner node A′ and the ground terminal  59  allowing the signal to be filtered at the inner node A′ and has, coupled in series, a resistance R 12  and a capacitance C 19 . 
     Similarly to the first actuator circuit  40 , the second actuator circuit  45  biases the second solenoid  18  in relation to the duty signal of the second activation signal  22 , providing, in particular, a current to the actuator circuit  40  during the charge time period T ON′ . 
     This allows a low energy consumption improving the performance of the automatic device  10  itself. 
     Furthermore, the first actuator circuit  40  and the second actuator circuit  45  to satisfy defined control and safety regulations can, instead of a first capacitance C 1  and a second capacitance C 2 , have many capacitances C 1 ′, C 2 ′, C 3 ′ and C 10 , C 11  and C 12 , respectively, arranged in series and placed between the respective inner node A and A′ and the output node E and E′ as highlighted in  FIG. 4 . 
     Similarly, the first actuator circuit  40  and the second actuator circuit  45  to increase efficiency of energy conversion can, as an alternative to the first diode D 1  and the second diode D 2 , have two or more diodes, D 3  and D 4 , as well as D 5  and D 6 , respectively, arranged in parallel and coupled between the output node E, E′ and the ground terminal  59 . Such diodes can, in some cases, be Schottky diodes. 
     It is worth noting that the first resistance R 33  and the second resistance R 72 , in series respectively with the output nodes E, E′, could be replaced by a pair of inductances of a value similar to the first and second inductance L 1  and L 2 , without for this reason jeopardizing the operation of the actuator circuits  40  and  45 , as well as of the automatic device  10 . Therefore, it is possible to improve the attenuation of possible interferences conducted from and towards the nodes E, E′ at the first drive signal  41  and at the second drive signal  42 , also allowing current specific regulations to be respected, like for example the regulations known by the acronym EMC (Electro-Magnetic Compatibility). 
     Furthermore, the diode DZ 3  and the diode DZ 6  may not be present without for this reason jeopardizing the operation of the actuator circuits  40  and  45 , as well as of the automatic device  10 . 
     Moreover, according an embodiment there is retroaction between the first actuator circuit  40  and the electrical unit  5 . According to this embodiment, the automatic device  10  comprises an unique connector CN 1 , shown repeatedly in  FIGS. 4 ,  6  and  13 , which represents a unitary and main connection interface between the electrical unit  5  and the peripherals of the automatic device  10 , allowing quick and easy connection. 
     In particular, the connector CN 1  receives the first supply voltage VDC through the first terminal  16  and the second supply voltage VBB through the second terminal  20 , and it is suitably coupled to the ground terminal  59 . 
     In particular, the connector CN 1  has three successive terminals that contact a command reading circuit  100 , shown in  FIG. 13 , which receives respective signals  101 ,  103  coming through the set of terminals  27  from the command panel  6 . Such signals  101 ,  103  are interpreted by the microcontroller  30  so as to generate the activation signal for the enable circuit  46  for driving the first actuator circuit  40  and the second actuator circuit  45 . 
     Finally, the connector CN 1  has three further terminals that contact the valve means  7  respectively coupling the output terminals  34 ,  35  and the ground reference terminal  59  of the first  40  and of the second actuator circuit  45 , to respective terminals  41  and  42  of the first solenoid  17  and of the second solenoid  18 . 
     Even more specifically, a fourth input terminal of the connector CN 1  is arranged to receive a switching signal Command_Switch, a fifth input terminal of the connector CN 1  is arranged to receive a selection signal Mode_switch and a sixth terminal of the connector CN 1  is arranged to receive the return signal Switch_GND provided by the connection with the set of terminals  27  towards a command panel  6 . 
     The selector  50 , illustrated in  FIG. 6 , receives, in particular through the connector CN 1 , the first supply voltage VDC and the second supply voltage VBB respectively at a second input terminal  51  and at a first input terminal  52 , and it is coupled to the ground terminal  59  to supply, to an output terminal, the third supply voltage VCC_Pos. In particular, the third supply voltage VCC_Pos is the maximum voltage between the input supply voltages. According to an embodiment, the selector  50  comprises a first diode D 12 , in series with the first input terminal  51 , and a second diode D 13 , in series with the second input terminal  52 , as well as a filter F 3  suitably coupled in series with the first diode D 12  and with the second diode D 13  and coupled to the output terminal  56 . 
     Advantageously, the first diode D 12  and the second diode D 13  are of the Schottky type and in particular go into blocking mode in the presence of possible inverse voltages at the respective input terminals, blocking the passage of current. 
     The first filter F 3  comprises a first capacitance C 8 , a first inductance L 6  and a second inductance L 7  and attenuates possible interferences conducted, from and towards the first input terminal  51  and the second input terminal  52 , in particular respecting current specific regulations, like for example the regulations known by the acronym EMC (Electro-Magnetic Compatibility). 
     A fuse RT 1  and a third diode DZ 2 , Zener type, are coupled to the output terminal  56  and make a protection from possible over voltages and over currents. Indeed, when there are over voltages the third diode DZ 2  goes into inverse conduction, whereas the fuse RT 1  is activated once a so-called marker current has been exceeded. 
     It is worth noting that the first inductance L 6  and the second inductance L 7  of the filter F 3  could be replaced by a pair of short-circuits, without for this reason jeopardising the operation of the selector  50 , as well as of the automatic device  10 . 
     In the most general form, the selector  50  operates in the presence of the first supply voltage VDC and the second supply voltage VBB and the battery pack  4  take care of possible supply voltage drops of the electricity main  2 , as a buffer battery. 
     In particular, during operation, the first diode D 12  and the second diode D 13  automatically impose upon an inner node X of the selector  50  a voltage that in value is the greater from the first supply voltage VDC and the second supply voltage VBB. A possible temporary or extended drop in the first supply voltage VDC makes just the first diode D 12  conduct automatically connecting the battery pack  4  and offering a low direct voltage drop at the output terminal  56 . 
     Therefore, the first diode D 12  and the second diode D 13  allow a non-conflicting connection between the first supply voltage VDC and the second supply voltage VBB avoiding the first supply voltage VDC from overloading the battery pack  4  damaging them and at the same time avoiding the battery pack  4  being needlessly consumed. 
     According to a possible embodiment, such battery pack  4  provide a voltage of 6V, with four 1.5V batteries arranged in series, whereas the voltage in output from the transformer provides a nominal voltage equal to 7V. 
     In further embodiments, the second supply voltage VBB has a field of variation of between 4V and 6.4 V according to the level of charge of the battery pack, whereas the first supply voltage VDC has a field of variation of between 4V and 8.5 V. 
     The enable circuit  46 , illustrated in  FIG. 5 , is supplied at a supply terminal  43  by the third supply voltage VCC_Pos and is enabled at an input terminal  44  by an enabling signal  49 , provided by the microcontroller  30 , to generate the fourth supply voltage VCC at an output terminal  147 . 
     In particular, the enable circuit  46  comprises a first transistor Q 2  coupled between the supply terminal  43  and the output terminal  147  with a command terminal coupled to the input terminal  44  through the interposition of a second transistor Q 4 , which is suitably coupled to the ground terminal  59  and has a command terminal coupled to the input terminal  44 . 
     Preferably, the first transistor Q 2  is of the bipolar PNP type and is coupled to a common emitter through the interposition of a first resistance R 11 . 
     Moreover, a first resistive divider R 15 -R 16  allows the voltage of the enabling signal to be regulated at the command terminal of the second transistor Q 4 , whereas a second resistance R 13  arranged between the second transistor Q 4  and the first transistor Q 2  allows the bias voltage at the latter to be regulated. 
     A buffer capacitance C 14  is coupled in parallel between the output terminal  147  and the ground terminal  59 , allowing the voltage at the output terminal  147  to be stabilized. 
     It is worth noting that the enabling circuit  46  is substantially a safety circuit made to satisfy defined current regulations. Alternatively, a replacement resistance R 9  could be arranged between the input terminal  43  and the output terminal  147  of the enable circuit  46 , supplying the fourth supply voltage VCC directly and permanently to the first actuator circuit  40  and to the second actuator circuit  45 . 
     According to the present embodiment, the regulation circuit  60 , shown in  FIG. 7 , at an input terminal  61  receives the third supply voltage VCC_Pos and supplies the fifth supply voltage VDD, which is substantially a stabilised voltage suitable for feeding the electrical unit  5 , to an output terminal  65 . 
     The regulation circuit  60  is also coupled to the ground terminal  59 . 
     An integrated linear regulator U 2  is arranged between the input terminal  61  and the output terminal  65 , a first capacitance C 15  and a second capacitance C 17  are coupled in parallel arranged between the input terminal  61  and the ground terminal  59 , whereas a third capacitance C 18 , a fourth capacitance C 16  and a pair of Zener diodes DZ 4  and DZ 5  are coupled in parallel between the output terminal  65  and the ground terminal  59 . 
     In the present embodiment, the electrical unit  5  comprises, as shown in  FIG. 8 , a stabilization network  37  associated with the microcontroller  30 , which comprises passive components able to stabilise the operation. 
     In particular, the stabilisation network  37 , supplied at a first node  65  by the fifth supply voltage VDD, has a second node  66  coupled to the ground terminal  59 , a first capacitance C 4  and a second capacitance C 5  coupled in parallel with each other between the first node  65  and the second node  66 , with the ends coupled to respective supply pins VDD and VSS, VDD′ and VSS′ of the microcontroller  30 . 
     In particular, the first capacitance C 4  and the second capacitance C 5  absorb possible variations in current that can be generated by sources either inside or outside the electrical unit  5  due to quick switching of electrical currents and voltages. 
     Moreover, a delayed circuit comprising a first resistance R 1  and a third capacitance C 7  arranged in series between the first node  65  and the second node  66 , as well as a second resistance R 5  coupled between a third node  64  and a pin MCLR_ICD of the microcontroller  30 , allows the fifth supply voltage VDD to be stabilized ensuring that the microcontroller  30  starts up with a voltage that is as stable as possible. 
     A first clock reference circuit  38  coupled with two terminals I and L, to two different pins OSC 1  and OSC 2  of the microcontroller  30  and coupled to the ground terminal  59  that comprises a ceramic resonator Y 1 . 
     The ceramic resonator Y 1 , in particular, allows an onboard timer installed in the microcontroller  30  to be oscillated at an appropriate frequency allowing a correct operation of a logic part installed in the microcontroller  30  and allowing the microcontroller  30  to carry out timed functions. 
     According to the present embodiment, a second reference circuit  39  is present in the electrical unit  5  and comprises a timer used as independent source for checking the operation of the first clock reference circuit  38  and vice-versa. 
     In particular, the second reference circuit  39 , as illustrated in  FIGS. 20 and 21 , comprises a switch S arranged between the fifth supply voltage VDD and the ground terminal  59  activated by a command signal  62  coming from the microcontroller  30 . The switch S suitably drives an Schmitt trigger inverter TR, coupled in cascade, which has a lower threshold voltage V ML  and an upper threshold voltage V MH . 
     A suitable resistance R 76  is arranged between an output terminal RC 0  of the switch S and an input terminal RC 1  of the inverter TR whereas a capacitance C 44  is coupled between the input terminal RC 1  and the ground terminal  59 . 
     In particular, when the command signal  62  of the switch S switches in relation to a third signal V P  present at the output terminal P of the inverter TR, a first signal V N  at the output terminal RC 0  switches. Based upon the value of the resistance R 76  and of the capacitance C 44 , a second signal V M  with exponential ramp is generated at the input terminal RC 1 . The second signal V M  drives the inverter TR and the third signal V P  has a waveform substantially analogous to that of the first signal V N  but suitably shifted in time. The time sequences of the first signal V N , of the second signal V M  and of the third signal V P  are shown in  FIG. 22 . 
     The first signal V N  has a duty cycle substantially independent from the inner peripherals of the microcontroller  30 , in particular it has a period T ref  equal to:
 
 T   ref   =T   H   +T   L  
 
     Where T H  is the time with presence of high logic level signal
         T L  is the time in the absence of the signal       

     The period T ref  is compared by the microcontroller  30  with a period of the clock generated by the ceramic resonator Y 1  to satisfy defined control and safety regulations. 
     A comparison between the magnitudes provided by the first ceramic resonator Y 1  and by the first reference circuit  38  as well as a suitable management of the signals of the second reference circuit  39  allows the microcontroller  30  to recognize possible deviations between the magnitudes provided, placing if necessary the electrical unit  5  in a stop state and the electronic device  10  in a safety state. 
     The switch S and the inverter TR can be integrated directly into the microcontroller  30  and, in this case, the output terminal RC 0  and the input terminal RC 1  are pins of the microcontroller  30 . 
     The microcontroller  30 , as shown in  FIG. 8 , has a plurality of further input pins RA 0 , RA 1 , RA 2 , RA 3 , RA 5 , RE 0  coupled to a plurality of control peripherals suitable for providing analogue signals, as well as further pins provided to receive digital signals or rather signals with a significant interpretation only based upon two levels of discrete voltages, of the “high” or “low” or “0” or “1” type and that shall be described hereafter. 
     According to the present embodiment, the voltage generator  85 , shown in  FIG. 9 , is supplied at a supply terminal  32  by the third supply voltage VCC_Pos and is activated by a first command signal  86  received at an enabling terminal  33  to supply a high voltage impulsive bias signal  83  to an output terminal  89 . 
     The first command signal  86  is generated by the microcontroller  30  and is of the impulsive type regulated according to the fourth supply voltage VCC, suitably measured by said microcontroller  30  through a fifth voltage measurer  160 , which is described hereafter. 
     In particular, the voltage generator  85  comprises a first transformer T 1  with a primary winding the terminals I 1 -I 2  of which are respectively coupled to the supply terminal  32  and to a switch Q 6  which is suitably coupled to the ground terminal  59  and is activated by the first command signal  86 . 
     The first transformer T 1  has a secondary winding the terminals O 1 -O 2  of which are respectively coupled with the output terminal  89  and with the ground terminal  59 . 
     According to an embodiment, the first transformer T 1  has a transformation ratio equal to 10. 
     A filtered divider element  88  is arranged between the first enabling terminal  33  and the switch Q 6  to process the first command signal  86  and dynamically actuate the switch Q 6 . 
     The filtered divider element  88  is an R-C network and has a first resistance R 29  as well as a second resistance R 31  and a first capacitance C 29 , coupled in parallel with each other, arranged between the enabling circuit  33  and the ground terminal  59 . 
     Moreover, a second capacitance C 24  and a third capacitance C 25 , for filtering, coupled in parallel to each other, and arranged between the input terminal  32  and the ground terminal  59  allow possible interferences present in the third supply voltage VCC_Pos to be filtered. 
     Furthermore, a first diode DZ 1 , Zener type, and a second diode D 8  are coupled in parallel to the primary winding I 1 -I 2  of the first transformer T 1 . 
     Finally, a resistance R 73  is arranged between the ground terminal  59  and a conducting terminal of the switch Q 6  to limit the maximum reachable value by the conducting current of the switch Q 6 . 
     The bias signal  83  generated at the output terminal  89  is a high voltage alternating pulse train signal suitable for actuating the flame detector  90  as well as for feeding the spark circuit  80 . 
     The spark circuit  80  receives the bias signal  83  at an input terminal  79  coupled to the output terminal  89  of the voltage generator  85 , and is activated by the microcontroller  30  through a second command signal  57 , suitably having a pulse train, received at a second enabling terminal  78 . 
     The spark circuit  80 , between a first output terminal  25  and a second output terminal  26  provides a suitable discharge signal  84  with a high voltage difference, that is sufficient to generate sparks or electrical discharges, to generate the pilot flame, in a suitable first electrode  29  at the first nozzle  8  of the pilot burner  11 . 
     According to the present embodiment, the second output terminal  26  is coupled to a further ground terminal  36 . 
     In particular, the spark circuit  80  comprises a second transformer T 2  with a primary winding the terminals I 3 -I 4  of which are coupled between the input terminal  79  and the ground terminal  59  and a secondary winding with the terminals O 3 -O 4  coupled to the first output terminal  25  and to the second output terminal  26 . 
     According to an embodiment, the first output terminal  25  is coupled to a third connector CN 3  and the second output terminal  26  is coupled to a second connector CN 2 . 
     Moreover, the spark circuit  80  comprises a third diode D 7  a first resistance R 21  and a second resistance R 22 , in series, coupled between the input terminal  79  and the primary winding I 3 -I 4  of the second transformer T 2 , whereas a first capacitance C 26  is coupled between the second transformer T 2  and the ground terminal  59 . 
     A triggering element  82  is arranged between the second transformer T 2  and the ground terminal  59  and comprises a thyristor Q 7  of the SCR triggering type and a fourth diode D 9 , arranged in antiparallel with each other. 
     The thyristor Q 7  is activated by the second command signal  57  suitably regulated in voltage by a filtered divider R 30 -R 32 -C 43  coupled between the enabling terminal  78  and the ground terminal  59 . 
     As regards the operation of the voltage generator  85  as well as of the spark circuit  80 , the first impulsive command signal  86  with a predetermined duty cycle, dynamically activates the switch Q 6  between a closed operative condition, i.e. coupled to the reference voltage GND, and an open operative condition for a predetermined number of switches per second. 
     When the switch Q 6  is in the closed operative condition an electric current crosses the primary winding I 1 -I 2  of the first transformer T 1  and a suitable energy is accumulated, a portion of such energy transfers to the secondary winding O 1 -O 2 , generating a negative semi-wave of the bias signal  83 . 
     When the switch Q 6  is in the open operative condition, a mesh is suitably formed between the primary winding I 1 -I 2  of the first transformer T 1 , the first diode DZ 1  and the second diode D 8 . In particular, a current crosses the first diode DZ 1 , which is taken into inverse conduction, and the second diode D 8 , which is taken into direct conduction. 
     In such an open operative condition, the remaining portion of the energy accumulated by the first transformer T 1  transferred to the secondary winding O 1 -O 2  generates the remaining positive semi-wave of the bias signal  83 . This semi-wave charges the fourth capacitance C 26  of the spark circuit  80  through the third diode D 7 , the resistance R 21  and the resistance R 22 . 
     After the defined number of switches of the first command signal  86 , the fourth capacitance C 26  of the spark circuit  80  suitably charges to a predetermined high voltage value. 
     When the thyristor Q 7  goes into conduction, activated by the second command signal  57 , a mesh is formed between the primary winding I 3 -I 4  of the second transformer T 2  and the fourth capacitance C 26 . 
     At the same time, the second transformer T 2 , with a high transformation ratio, generates the discharge signal  84  at the secondary winding O 3 -O 4  with a high voltage and in particular able to overcome the dielectric rigidity of air, producing sparks, at the first electrode  29  arranged near to the first nozzle  8  of the pilot burner  11 , of sufficient energy to ignite the gas and generate the pilot flame. 
     The output terminal  25  is advantageously connected to a discharge terminal associated with the first electrode  29  through the second connector CN 2  and the third connector CN 3 , both of the type suitable for high voltages. 
     A suitable conductive return mesh of the discharge current is formed through the pilot burner  11 , the first nozzle  8  and the discharge terminal connected to the second connector CN 2 , as well as through the further ground terminal  36  and the output terminal O 3  of the secondary of the second transformer T 2 . 
     According to an embodiment, the fourth capacitance C 26  is charged to a voltage of about 120-140V and through the second transformer T 2  causes a spark having a voltage of about 15-30 kV near the first electrode  29 . 
     The spark circuit  80 , in some embodiments, could be integrated in the electrical unit  5 . 
     A connection block  190 , represented in  FIG. 9 , is arranged between the ground terminal  59  and the further ground terminal  36  to make a star network and thus ensure the electrical continuity in the automatic device  10  minimising the propagation of the interferences generated by the discharge signal  84 , respecting defined current regulations, in particular EMC (Electro-Magnetic Compatibility). 
     For functional purposes, the connection block  190  can be replaced by a resistance of sufficiently high value respecting current regulations. 
     The detector  90 , illustrated in  FIG. 10 , is supplied by the bias signal  83  received at an input terminal  93  and allows it to be checked whether there is a pilot flame in the pilot burner  11 , exploiting an ionization detection principle. In particular, through such an ionization detection principle, the detector  90  detects the presence of a flame by analyzinq a current received at a control terminal  91  which is coupled to a second ionization electrode  19  introduced in the pilot flame and suitable biased through the bias signal  83 . 
     The detector  90 , suitably sized, has sensitivity and a rate of response that satisfy the current regulations. 
     The detector  90 , connected to the ground terminal  59 , receives the flame detection signal  94  at the control terminal  91 . Moreover, the detector  90  comprises an activation terminal  95  that receives an activation signal  96 , generated by the microcontroller  30 , and an output terminal  92  that provides a verification signal  99  having a pulse train. 
     The verification signal  99  is suitably analyzed by the microcontroller  30  within a predetermined time period. 
     As known to the skilled in the art, the ionization detection principle makes it possible to check for the presence of a flame surrounding two electrodes subject to a potential difference. In such a condition, the two electrodes are, indeed, crossed by a weak electric current whereas, by inverting the polarity of the voltage in the presence of a flame between the two electrodes, the current becomes substantially zero. 
     The behaviour of two electrodes introduced in the flame can be simulated with a circuit comprising a rectifying diode with high direct resistance. 
     In particular, in the present embodiment, the first nozzle  8  being metallic and being coupled to the further ground terminal  36  defines the second electrode. Therefore, in the presence of a flame, when the ionization electrode  19  has a positive voltage with respect to the first nozzle  8  there is a passage of current and the flame is recognized as lit. On the other hand, when by inverting the polarity of the voltage, the voltage difference between the ionization electrode  19  and the first nozzle  8  is negative there is no passage of current even if the flame is lit. 
     Furthermore, in the absence of a flame, when the electrode  19  has a positive or negative voltage with respect to the first nozzle  8 , there is no passage of current since the mixture of air and fire-proof gas is an electrical insulator at the voltage values used. 
     The detector  90  comprises a first capacitance C 35  arranged between the input terminal  93  and a first inner node W, a first resistance R 41  and a second resistance R 42 , in series, coupled between the first inner node W and the control terminal  91 . 
     Moreover, the detector  90  comprises a first filtering element  97  and a second filtering element  98 , consisting of R-C circuits, coupled together in series and arranged between the first inner node W and a second inner node Y. 
     The first filtering element  97  comprises a third resistance R 46  coupled to the first inner node W and coupled to a second capacitance C 34  in turn connected to the ground terminal  59 . Similarly, the second filtering element  98  comprises a fourth resistance R 45  coupled to a third capacitance C 33  in turn connected to the ground terminal  59 . 
     A divider comprising a fifth resistance R 39  and a sixth resistance R 48 , arranged between the activation terminal  95  and the ground terminal  59 , allows the rest voltage of the inner node Y to be suitably regulated from the level of the activation signal  96 . 
     Furthermore, a first bipolar transistor Q 9  arranged between the output terminal  92  and the ground terminal  59  is commanded by a signal coming from the second inner node Y. 
     Finally, a seventh resistance R 38  is arranged between the activation terminal  95  and the output terminal  92 . 
     The detector  90  can have a protection and compensation network for the temperature variation that comprises a second transistor Q 10 , suitably diode-connected, arranged between the second inner node Y and the ground terminal  59  through an eighth resistance R 47  of high resistive value. 
     As regards the operation of the detector  90 , a current that averages out at zero detected by the detection signal  94  keeps the average value of the alternating voltage present at the first inner node W practically unchanged, also keeping the second inner node Y at a continuous voltage level upper than a conduction voltage of the first transistor Q 9 . 
     Therefore, the first transistor Q 9  is kept in a conduction area and provides the output terminal  92  with a voltage that the microcontroller  30  interprets as low logic level, i.e. “0” or absence of flame. 
     On the other hand, a current of positive average value detected by the detection signal  94  lowers the average value of the alternating voltage present at the first inner node W, also lowering the continuous voltage present at the second inner node Y. In this way, the first transistor Q 9  comes out from the conduction area zeroing the current through the seventh resistance R 38  that is no longer crossed by current and the voltage at the output terminal  92  increases. The microcontroller  30  interprets such a voltage as high logic level, i.e. “1” detecting a presence of flame. 
     Advantageously, the verification signal  99  is of the type with rectangular wave and is generated by the detection signal  94  which is suitably alternated and generated by the bias signal  83  having a pulse train. 
     Moreover, thanks to the fact that the verification signal  99  is analyzed through the microcontroller  30  in a predetermined time period, it is possible to distinguish a real presence of a flame from an anomalous or parasite conductive pathway that could give false flame detection. 
     Indeed, possible conductive pathways created in the presence of carbon residues deposited due to poor combustion or else in the presence of foreign bodies in the pilot burner  11 , or even in the presence of aesthetic embers of mineral substance that are often scattered in the combustion chamber, can easily be detected by the microcontroller  30 . 
     Moreover, it is worth noting that since the bias signal  83  alternates with a succession of pulse trains, equipped with a suitably defined duration and frequency, as well as a peak voltage of around one hundred volts, it allows the voltage generator circuit  85  to ensure a transfer to the detector  90  of a peak current of the detection signal  94  with a value around the unit of microamperes, adequate for normal requirements. 
     The time sequences of the bias signal  83 , of the detection signal  94  and of the verification signal  99  are schematically shown in  FIG. 23 . 
     In particular, the detection signal  94  has a first active time period T S  and a second passive time period T O  that are defined by the bias signal  83 . 
     Even more particular, the electrical unit  5  through the first command signal  86  activates in pulses the voltage generator  85 , which generates the high voltage alternating bias signal  83  at the output terminal  89  for the first time period T S  that is transferred as detection signal  94  and biases the second ionization electrode  19 . At the same time, the microcontroller  30 , through the activation signal  96 , activates the detector  90  and measures the verification signal  99  for the same first time period T S . 
     After such a predetermined time window T S , the electrical unit  5  deactivates the first command signal  86  and the voltage generator  85  stops providing the bias signal  83  that cancels out like the detection signal  94  and stops biasing the second ionization electrode  19 . 
     Simultaneously, even if the detector  90  shows for the second time period T O  the (desired) loss of detection signal  94 , the microcontroller  30  suspends the acquisition of the verification signal  99 . 
     Advantageously, the second time period T O  is greater than the first time period T S . 
     The measurement of the presence of flame is detected through the electrical unit  5  only during the first active time period T S . Advantageously such a time period T S  is reduced to fractions of the order of a tenth of a second that substantially is the period in which the pulse train of the bias signal  83  is kept active at the voltage generator  85 . A substantial saving in energy is thus obtained. 
     Indeed, during the second time period T O , the bias signal  83  is deactivated with a substantial saving of energy especially in the case in which the electronic device  10  is supplied exclusively by the battery pack  4 . 
     The bias signal  83  has a time sequence of alternating voltage pulse trains that has frequency and duty cycle equal to:
 
Frequency detection  f   R =1 /T   R =1/( T   S   +T   O )
 
Duty cycle detection  d   R   =T   S /( T   S   +T   O )
 
     Which advantageously allows the consumption to be kept low whilst still ensuring a real and immediate recognition following the real loss of flame with a maximum reaction time of less than the one second that fully satisfies the regulations of the regulations. 
     A control peripheral of the automatic device  10  is a current measurer  110 , illustrated in  FIG. 11 , which when activated by the microcontroller  30 , through an enabling signal  115 , at a first input terminal  112 , coupled to the detection terminal  31  of the first actuator circuit  40 , detects a signal proportional to the current present at the first output terminal  34 . The current measurer  110  provides such a measured current value I_Measure to an output terminal RE 0  coupled to the microcontroller  30  to carry out some checks. 
     In particular, the current measurer  110  comprises an amplifier with common collector, coupled to suitable resistive and capacitive elements, which is enabled by the enabling signal  115 . 
     The automatic device  10  comprises further voltage measurers, illustrated in  FIG. 12 , activated by a single enabling signal  122 , generated by the same microcontroller  30 , and suitable for providing the microcontroller  30  with a measurement of the voltages present in the automatic device  10  for specific checks and necessary comparisons and regulation. 
     In particular, a first voltage measurer  120  measures the fifth supply voltage VDD present at the output terminal  65  of the detection circuit  60 , using a resistance R 71  and providing such a measurement to a first analogue input RA 2  of the microcontroller  30 . 
     A second voltage measurer  130  implicitly measures the reference voltage GND of the ground terminal  59  and provides it to a second analogue input RA 5  of the microcontroller  30 . 
     A third voltage measurer  140  measures the supply voltage VBB supplied by the battery pack  4  and through a network of substantially R-C passive elements generates a measured supply voltage VBB_Measure that is supplied to a third analogue input RA 0  of the microcontroller  30 . 
     A fourth voltage measurer  150  takes the fifth supply voltage VDD and, through a network of substantially R-C passive elements and a bipolar transistor coupled with diode, generates a reference voltage Vref_measure that is supplied to a fourth analogue input RA 1  of the microcontroller  30 . 
     In particular, the measured reference voltage Vref_measure is acquired at an input independent both from the fifth supply voltage VDD measured through the first voltage measurer  120 , and from the reference voltage GND detected through the second voltage measurer  130 . Therefore, the microcontroller  30  uses the three distinct magnitudes that are compared with each other in the safety checks for self-diagnosis and in the satisfaction of the regulations of the regulations. 
     Finally, a fifth voltage measurer  160  detects the fourth supply voltage VCC and through a network of substantially R-C passive elements generates a voltage VCC_Measure that is supplied to a fifth analogue input RA 3  of the microcontroller  30 . 
     In particular, it is worth highlighting that through a suitable activation of the transistor Q 16  by the microcontroller  30  all of the measuring blocks  140 ,  150  and  160 , shown in  FIG. 12 , are able to be deactivated/activated simultaneously. 
     More in particular, the deactivation of such measuring blocks saves a few hundred microamperes of supply current. 
     Further suitable blocks and peripherals can be coupled or present in the automatic device  10  to satisfy specific requirements. 
     A suitable interface block  180 , shown in  FIG. 14 , comprises a fifth connector J O , connected to the fifth supply voltage VDD and to the ground terminal  59  as well as to the microcontroller  30  through three command terminals  181 ,  182 ,  183  and allows rapid connection to the microcontroller  30  for rapid programming. 
     Finally, the automatic device  10  comprises a diagnostic block  170 , shown in  FIG. 15 , which is supplied by the fifth supply voltage VDD and is coupled to the ground terminal  59  as well as receives a first diagnostic signal  172  and a second diagnostic signal  171  from the microcontroller  30  suitable for providing the diagnostic circuit  14  with four interface signals +Vdd, TXD, −GND, RXD, through a sixth connector CN 6 . 
     The diagnostic circuit  14  can comprise an acoustic element for emitting encoded sounds, or else it can consist of a luminous device for emitting encoded flashes or it can be a serial communication interface for exchanging data through a suitable protocol. 
     As regards the operation of the automatic device  10 , according to the present embodiment, for ignition of the automatic device  10  the electrical unit  5  from the command circuit  6  receives the start signal Start, which can be generated by an external command signal, or received from a user, or from means for detecting the room temperature. 
     In the ignition step, the electrical unit  5  commands the voltage generator  85  in pulses through the first command signal  86 , which, at the output terminal  89 , generates the high voltage alternating bias signal  83  suitable for commanding the spark circuit  80  and for driving the detector  90  both enabled by the microcontroller  30 . 
     The detector  90  detects the detection signal  94  from the second ionization electrode  19  close to the pilot burner  11  and through the flame detection principle provides the microcontroller  30  with the verification signal  99 , detecting an initial absence of flame. 
     Once it has been verified that there is no flame, otherwise a breakdown symptom, since the commands to open the gas are still inactive, the electrical unit  5  enables the enable circuit  46  with activation of the enabling signal  49  and the actuator circuit  40  with the activation of the first activation signal  21 . 
     Simultaneously, the electrical unit  5  with the second command signal  57  activates the spark circuit  80 , which generates the discharge signal  84  through the formation of an electrical discharge repeated over time at the corresponding output terminals  25  and  26  to make a series of sparks in a suitable first electrode  29  at the first nozzle  8  to generate the pilot flame in the pilot burner  11 . 
     Simultaneously, the first actuator circuit  40  suitably biases the first solenoid  17  in relation to the duty cycle of the first activation signal  21 , regulating the passage of the gas through the pilot burner  11 . 
     The ignition sequence of the pilot flame is completed when the verification signal  99  generated by the detector  90  and analyzed by the microcontroller  30  in the predetermined time window detects a continuous flame that hits the second ionization electrode. 
     In this case, it is deactivated the second command signal  57  at the spark circuit  80  and the discharges at the first electrode  29  are stopped. The detector  90  continues to check the pilot flame in the pilot burner  11  thanks to the second ionization electrode  19  and the electrical unit  5  is ready for the ignition of a flame in the main burner  12 , if required, with the activation of the second activation signal  22  and the corresponding bias of the second solenoid  18 . 
     Simultaneously, the microcontroller  30  through the peripherals checks the correct operation of the automatic device  10 . 
     In the case of anomalies, the microcontroller  30  activates the diagnostic interface block  170  that provides respective signals that can be processed by the diagnostic circuit  14 , coupled to the electrical unit  5 , which according to the requirements and the design specifications, allows suitable and specific alarm signals to in turn be generated. 
     An embodiment of the present invention also refers to a method for driving an automatic device for the ignition and control of a gas apparatus, of the type described previously for which details and cooperating parts having the same structure and function shall be indicated with the same reference numbers and symbols. 
     A method according to an embodiment of the present invention refers to an automatic device  10  of a gas apparatus  1  which is equipped with a pilot burner  11  and a main burner  12 , coupled in the usual way. Moreover, suitable electrically controlled valve means  7  allow the flow of gas to be regulated from a main pipe  28  towards a first nozzle  8 , associated with the pilot burner  11 , and to a second nozzle  13 , associated with the main burner  12 . 
     Such a driving method is basically based upon the dynamic actuator of a first actuator circuit  40  and of a second actuator circuit  45  through, respectively, a first activation signal  21  and a second activation signal  22  having a pulse train, generated by an electrical unit  5  with a microcontroller. The pulses of such activation signals  21 ,  22  have a predetermined duty cycle
 
duty cycle= T   ON /( T   ON   +T   OFF )
 
     where: T ON  is the activation time period
         T OFF  is the deactivation time period.       

     The valve means  7  are dynamically polarized by such actuator circuits  40 ,  45  regulating the charge state according to the duty cycle of the pulse train of such activation signals  21 ,  22 , allowing a substantial saving of energy. 
     The actuator circuits  40 ,  45  are made so that, during the actuator of the respective activation signal  21 ,  22 , the voltage at a respective output node E, E′ is less than the voltages of any inner node, and in particular less than the voltage of the ground terminal  59 . 
     Substantially, according to an embodiment of the present method the actuator circuits  40 ,  45  are structurally and functionally similar. 
     Preferably, a first inductance L 1  and a first capacitance C 1 , arranged in series between a first supply terminal  47 , which receives a fourth supply voltage VCC, and the output node E associated with a first output terminal  34 , as well as a first diode D 1  arranged between the output node E and an ground terminal  59 , are used to make the first actuator circuit  40 . 
     A first switch Q 1 , coupled between an intermediate inner node A and the ground terminal  59 , is suitably dynamically commanded by the electrical unit  5  through the first activation signal  21  having a pulse train. The intermediate node A is arranged between the first inductance L 1  and the first capacitance C 1 . 
     The valve means  7  and in particular a first solenoid  17  is connected to the first output terminal  34 , the first solenoid  17  also being connected to the ground terminal  59 . 
     In particular, in order to suitably actuate the first actuator circuit  40 , the method provides a preliminary step supplying the fourth supply voltage VCC and keeping the first switch Q 1  open. 
     Thereafter, the method provides actuating the first actuator circuit  40  through the first activation signal  21  having a pulse train, to dynamically polarize the valve means  7  and in particular the first solenoid  17 . 
     For the dynamic bias of the first solenoid  17 , during the activation time period T ON  the first capacitance C 1  is advantageously connected to the ground terminal  59  through the first switch Q 1 . Therefore, the first actuator circuit  40  absorbs current from the first solenoid  17  making the voltage at the output node E negative. 
     Consequently, during the deactivation time period T OFF , the output node E is connected to the ground terminal  59  through the first diode D 1  which is taken into conduction and also absorbs a recirculation current coming from the first solenoid  17 . 
     The activation time period T ON  is foreseen to be substantially shorter than the deactivation time period T OFF . 
     Therefore, the first actuator circuit  40  provides a power transfer from the power supply, fourth supply voltage VCC, to the valve means  7  that is defined based upon the value of the duty cycle of the pulse train. In particular, there is an absorption of energy just during the activation time period T ON  of the first activation signal  21 . 
     The method provides modulating the duty cycle of the first activation signal  21  according to some parameters, like for example:
         value of the fourth supply voltage VCC;   value of the minimum current relative to an active condition of the first solenoid  17  to open the corresponding shutter;   temperature value of the first solenoid  17 .       

     Preferably, according to an embodiment of the present invention, a method provides at least one feedback measuring step which provides taking a measured current value I_Measure, proportional to the current value present at the first output terminal  34 , through a detection terminal  31 . The detection terminal  31  is connected near to the first output node E and suitably connected to the electrical unit  5 . 
     The method thus provides analyzing the measured current value I_Measure through the electrical unit  5 , comparing it with suitable reference values stored in the microcontroller and modulating the duty cycle of the first activation signal  21 , providing possible corrective compensations. 
     Similarly, to suitably actuate the second actuator circuit  45 , the method provides a preliminary step supplying the fourth supply voltage VCC and keeping a second switch Q 2  open. 
     Thereafter, the method provides actuating the second actuator circuit  45  providing the activation signal  22  having a pulse train to dynamically polarize the valve means  7  and in particular a second solenoid  18 . 
     The fourth supply voltage VCC is generated by an enable circuit  46  arranged in series with a selector  50  which is supplied by a first supply voltage VDC, supplied by a rectifying transformer  3  coupled in series and supplied by the network voltage VAC of the electricity main  2 , as well as by a second supply voltage VBB supplied by battery pack  4 . 
     A method provides equipping the selector  50  with a first diode  12  and with a second diode  13 , suitably arranged in series with the input terminals to supply an inner node X with the third continuous supply voltage VCC_Pos allowing a non-conflicting connection between the first supply voltage VDC and the second supply voltage VBB to avoid the first supply voltage VDC from overloading the battery pack  4  damaging them and consequently preventing the battery pack  4  from being needlessly consumed. 
     In particular, a method according to an embodiment of the present invention provides the steps of:
         initial automatic ignition, activating an spark circuit  80  suitable for generating a pilot flame at the first nozzle  8  of the pilot burner  11  when a start signal Start is received, through the electrical unit  5 .       

     More in particular, according to an embodiment of the present invention, the initial automatic ignition step provides the following preliminary steps:
         receiving and interpreting the start signal Start by the electrical unit  5  according to a specific and provided protocol, the start signal Start being emitted by a remote control panel  6 ;   activating a voltage generator  85  and activating a flame detector  90  and verifying an initial condition of pilot flame not present;   activating the voltage generator  85  to generate a spark through a discharge signal  84  near to the first nozzle  8 .       

     A method provides:
         activating the voltage generator  85  through a first command signal  86  with pulse train and with a predetermined duty cycle, generated by the electrical unit  5 , to generate the bias signal  83 , advantageously with alternating pulse train and having a high voltage, at the output terminal;   activating the spark circuit  80  through a second command signal  57 , also with pulse train with a predetermined duty cycle, generated by the electrical unit  5 , to generate the high voltage discharge signal  84  at the output terminal. The discharge signal  84 , compared to the voltage present at the ground terminal  59 , has a voltage difference suitable for generating suitable sparks at the first nozzle  8 .       

     According to an embodiment of the present invention, the electrical unit  5  according to a measured supply voltage VCC_Measure through a fifth voltage measurer  160  regulates the first command signal  86 . Moreover, a method provides:
         activating the detector  90  with a suitably timed activation signal  95  generated by the electrical unit  5  to control the pilot flame in the pilot burner  11 .       

     The method provides detecting the flame at the first burner  11 , through the ionization principle, receiving a detection signal  94  of a flame coming from a second ionization electrode  19  at a control terminal  91  and then providing a verification signal  99  to the electrical unit  5 . 
     The method then provides the step of analyzing the verification signal  99  in a predetermined time period through the electrical unit  5 . 
     According to an embodiment of the present invention, the flame detection signal  94  is an alternating signal with a negative voltage part and a positive voltage part to allow a real presence of flame to be distinguished from a parasite conductive pathway. 
     Once the pilot flame at the first nozzle  8  of the burner  11  has been generated and controlled, the method provides using the pilot flame as ignition source for a main flame near to the second nozzle  13  of the main burner  12 . 
     A method according to an embodiment of the present invention provides suitably actuating the second actuator circuit  45 , through the activation by the electrical unit  5  of the second activation signal  22  with pulse train to dynamically bias the valve means and in particular the second solenoid  18  and regulate the gas flow from the main pipe  28  to the main burner  12 . A second inductance L 2  and a second capacitance C 2 , in series between a second supply terminal  48  and a second output terminal  35 , as well as a second diode D 2 , arranged between the output terminal  35  and the ground terminal  59 , and a second switch Q 2  suitably dynamically commanded by the electrical unit  5  through the second activation signal  22  having a pulse train, are used to make the second actuator circuit  45 . 
     In an analogous way to what generally occurs, the method then provides the steps of:
         constantly checking the pilot flame in the pilot burner  11  through the detector  90  and the electrical unit  5 .       

     The method provides further steps of detection of the voltages and of the currents present in the automatic device  10 , through special blocks; 
     such steps are suitably timed by the electrical unit  5  with a microcontroller in a logic suitable for instantaneously detecting possible anomalies of the automatic device  10  as well as for minimising the energy consumption of the automatic device  10 . 
     Such steps, for example, provide the use of a first current measurer  110 , as well as of a first  120 , a second  130 , a third  140 , a fourth  150  and a fifth  160  voltage measurer, these being enabled simultaneously by the same enabling signal  122  provided by the electrical unit  5 . 
     Further detection blocks can be present to satisfy specific regulatory or requirements or specific and detailed needs. 
     An advantage of an automatic device according to an embodiment of the invention is its low energy consumption as well as its automatic management in terms of the flame ignition command, in terms of the flame control, and in terms of the safe restoring of the device in the presence of anomalies. Indeed, the actuator circuits, dynamically activated through the pulse train by the electrical unit with a microprocessor, bias the valve means with an energy transfer from the power supply just in the activation time period defined by the duty cycle of the pulse train of the respective activation signals. 
     A further advantage is given by the fact that thanks to the feedback between the first actuator circuit and the electrical unit it is possible to regulate the duty cycle of the pulse train of the activation signals activating the first actuator circuit and biasing the valve means with less use of energy. 
     Another advantage is given by the energy saving due to the timed actuation between the voltage generator, the spark circuit and the detector and by the fact that the detection of a flame through the verification signal is timed. 
     Such advantages, in particular, allow extremely low energy consumption with a substantial and unusual saving of energy, in this way allowing the automatic device to be suitably supplied with just the battery means for a significant period of time. 
     A further advantage of an automatic device according to an embodiment of the present invention is the versatility of use; indeed, the spark circuit can be commanded remotely for flame ignition and completely automatic control of the entire device. 
     Another advantage of the automatic device is given by the safety provided; indeed, the detector allows automatic quick checking of the flame leaving the electrical unit to safely manage the entire automatic device and in particular the valve means. A further advantage of the automatic device is given by the speed of response to possible anomalies of the pilot flame and to the capability to distinguish a real flame from another conductive pathway. In particular, the possible loss of the pilot flame is detected by the electrical unit  5  allowing resetting for safe management of the automatic device. Indeed, the detector uses the ionization flame detection principle and uses the alternating voltage pulse train detection signal. 
     Another advantage of the automatic device is given by the opportunity to activate the gas apparatus in complete safety through remote command, with a remote control or with a radio control. 
     Another advantage is the versatility of the present electronic device. Thanks to the fact that the valve means are biased through the actuator circuit activated by the activation signal with pulse train with duty cycle that can be regulated by the electrical unit, the automatic device can be adapted to a wider range of valve means equipped with substantially inductive solenoids with low supply voltage. In particular, the automatic device can replace other devices in existing apparatuses. 
     Another advantage of a pilot method according to an embodiment of the present invention is its efficiency linked to the low energy consumption required and to the completely electronic management in terms of the command to the spark circuit, in terms of the flame control and in terms of the control of the operation of the automatic device. 
     Moreover, such a method allows the device to be completely automatical and to be quickly restored or made safe. 
     From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention.

Technology Category: 2