Sensor device and method for flame presence detection

Abstract

A sensor device for detecting a flame comprises a carbon dioxide sensor for detecting a CO 2 concentration, a fuel sensor for detecting the combustion of a fuel, an electrostatic charge variation sensor for detecting electrostatic charge variations generated by the flame, and a control unit. The control unit is configured to acquire a carbon dioxide signal indicative of the concentration of carbon dioxide, a fuel signal indicative of the fuel combustion, and an electrostatic charge variation signal indicative of a difference between the electrostatic charge variations detected by a first and a second electrode of the electrostatic charge variation sensor, determine a quantized signal based on the electrostatic charge variation signal, determine an aggregate datum based on the carbon dioxide signal, the fuel signal and the electrostatic charge variation signal, and generate, based on the aggregate datum, a flame signal indicative of the presence or absence of the flame.

What is claimed is: 
     
         1 . A sensor device for detecting a presence or absence of a flame, the sensor device comprising:
 a carbon dioxide sensor configured to detect a concentration of carbon dioxide in air, generated by the flame;   a fuel sensor configured to detect combustion of a fuel used to produce the flame;   an electrostatic charge variation sensor including first and second electrodes spaced from each other and configured to detect respective electrostatic charge variations generated by the flame; and   a control unit operatively coupled to the carbon dioxide sensor, the fuel sensor, and the electrostatic charge variation sensor, wherein the control unit is configured to:
 acquire, through the carbon dioxide sensor, a carbon dioxide signal indicative of the concentration of carbon dioxide generated by the flame; 
 acquire, through the fuel sensor, a fuel signal indicative of a presence of combustion of the fuel used to produce the flame; 
 acquire, through the electrostatic charge variation sensor, an electrostatic charge variation signal indicative of a difference between the electrostatic charge variations detected by the first and the second electrodes; 
 determine a quantized signal by processing the electrostatic charge variation signal; 
 determine an aggregate datum indicative of an aggregation of the carbon dioxide signal, the fuel signal and the electrostatic charge variation signal; and 
 generate, as a function of the aggregate datum, a flame signal indicative of the presence or absence of the flame. 
   
     
     
         2 . The sensor device according to  claim 1 , further comprising a tubular body having an inlet opening and an outlet opening fluidically coupled to each other through a fluidic channel of the tubular body, which extends through the tubular body and which defines a fluidic path between the inlet opening and the outlet opening, in fluidic communication with the flame such that, in the presence of the flame, the fluidic channel is flown through by an air flow that is caused by the flame and that transfers from the inlet opening to the outlet opening;
 wherein the control unit, the carbon dioxide sensor, the fuel sensor, and the electrostatic charge variation sensor are disposed in the tubular body, and the carbon dioxide sensor and the fuel sensor extend into the fluidic channel.   
     
     
         3 . The sensor device according to  claim 2 , wherein the carbon dioxide sensor comprises:
 a light radiation emitter facing the fluidic channel and controllable by the control unit to emit light radiation through the fluidic channel;   a carbon dioxide optical filter facing the fluidic channel and configured to filter the light radiation emitted by the light radiation emitter so as to transmit the light radiation having a wavelength located in a carbon dioxide wavelength range comprising a carbon dioxide absorption wavelength; and   a carbon dioxide detector arranged at a distance from the light radiation emitter and configured to detect the light radiation filtered by the carbon dioxide optical filter and to generate the carbon dioxide signal;   wherein the light radiation emitter, the carbon dioxide optical filter, and the carbon dioxide detector are aligned in succession to each other along a carbon dioxide alignment axis extending through the fluidic channel.   
     
     
         4 . The sensor device according to  claim 2 , wherein the fuel sensor comprises:
 a fuel optical filter facing the fluidic channel and configured to filter radiation generated by the flame so as to transmit radiation having a wavelength located in a fuel wavelength range comprising a fuel emission wavelength; and   a fuel detector configured to detect the radiation filtered by the fuel optical filter and to generate the fuel signal;   wherein the inlet opening, the fuel optical filter, and the fuel detector are aligned in succession to each other along a fuel alignment axis extending through the fluidic channel.   
     
     
         5 . The sensor device according to  claim 2 , wherein the tubular body has a first end and a second end opposite to each other along a longitudinal axis of the tubular body, the first end configured to face the flame and the second end configured to extend on an opposite side of the tubular body with respect to the flame;
 wherein the first electrode extends at the first end of the tubular body, and the second electrode extends at the second end of the tubular body.   
     
     
         6 . The sensor device according to  claim 1 , wherein:
 the sensor device further comprises a temperature sensor configured to detect a temperature of the air dependent on the presence or absence of the flame; and   the control unit is operatively coupled to the temperature sensor, and further configured to:
 acquire, through the temperature sensor, a temperature signal indicative of the temperature of the air; and 
 in response to both the temperature signal being indicative of the absence of the flame and the flame signal being indicative of the presence of the flame, impose that the flame signal is indicative of the absence of the flame and/or generate a sensor warning signal. 
   
     
     
         7 . An ignition system for igniting a flame, the ignition system comprising:
 a dispensing device coupleable to a fuel source and controllable to dispense a fuel received from the fuel source;   a spark generator controllable to generate a spark and coupled to the dispensing device so as to produce the flame in response to the generated spark at the fuel dispensed by the dispensing device; and   a sensor device operatively coupled to the dispensing device and to the spark generator so as to detect a presence or absence of the flame, the sensor device comprising:
 a carbon dioxide sensor configured to detect a concentration of carbon dioxide in air, generated by the flame; 
 a fuel sensor configured to detect combustion of the fuel used to produce the flame; 
 an electrostatic charge variation sensor including first and second electrodes spaced from each other and configured to detect respective electrostatic charge variations generated by the flame; and 
 a control unit operatively coupled to the carbon dioxide sensor, the fuel sensor, and the electrostatic charge variation sensor, wherein the control unit is configured to:
 acquire, through the carbon dioxide sensor, a carbon dioxide signal indicative of the concentration of carbon dioxide generated by the flame; 
 acquire, through the fuel sensor, a fuel signal indicative of a presence of combustion of the fuel used to produce the flame; 
 acquire, through the electrostatic charge variation sensor, an electrostatic charge variation signal indicative of a difference between the electrostatic charge variations detected by the first and the second electrodes; 
 determine a quantized signal by processing the electrostatic charge variation signal; 
 determine an aggregate datum indicative of an aggregation of the carbon dioxide signal, the fuel signal and the electrostatic charge variation signal; and 
 generate, as a function of the aggregate datum, a flame signal indicative of the presence or absence of the flame. 
 
   
     
     
         8 . The ignition system according to  claim 7 , further comprising a main control unit operatively coupled to the dispensing device, the spark generator and the sensor device and configured to:
 receive from the sensor device the flame signal indicative of the presence or absence of the flame; and   control the dispensing device as a function of the flame signal, in such a way as to prevent the fuel from dispensing in response to the flame signal being indicative of the absence of the flame.   
     
     
         9 . The ignition system according to  claim 7 , wherein the sensor device further comprises a tubular body having an inlet opening and an outlet opening fluidically coupled to each other through a fluidic channel of the tubular body, which extends through the tubular body and which defines a fluidic path between the inlet opening and the outlet opening, in fluidic communication with the flame such that, in the presence of the flame, the fluidic channel is flown through by an air flow that is caused by the flame and that transfers from the inlet opening to the outlet opening; and
 wherein the control unit, the carbon dioxide sensor, the fuel sensor, and the electrostatic charge variation sensor are disposed in the tubular body, and the carbon dioxide sensor and the fuel sensor extend into the fluidic channel.   
     
     
         10 . The ignition system according to  claim 7 , wherein:
 the sensor device further comprises a temperature sensor configured to detect a temperature of the air dependent on the presence or absence of the flame; and   the control unit is operatively coupled to the temperature sensor, and further configured to:
 acquire, through the temperature sensor, a temperature signal indicative of the temperature of the air; and 
 in response to both the temperature signal being indicative of the absence of the flame and the flame signal being indicative of the presence of the flame, impose that the flame signal is indicative of the absence of the flame and/or generate a sensor warning signal. 
   
     
     
         11 . A detection method of a presence or absence of a flame through a sensor device,
 the sensor device comprising a carbon dioxide sensor configured to detect a concentration of carbon dioxide in air, generated by the flame, a fuel sensor configured to detect a combustion of a fuel used to produce the flame, an electrostatic charge variation sensor including first and second electrodes spaced from each other and configured to detect respective electrostatic charge variations generated by the flame, and a control unit operatively coupled to the carbon dioxide sensor, the fuel sensor and the electrostatic charge variation sensor, the detection method comprising steps of:
 acquiring, by the control unit and through the carbon dioxide sensor, a carbon dioxide signal indicative of the concentration of carbon dioxide generated by the flame; 
 acquiring, by the control unit and through the fuel sensor, a fuel signal indicative of a presence of the combustion of the fuel used to produce the flame; 
 acquiring, by the control unit and through the electrostatic charge variation sensor, an electrostatic charge variation signal indicative of a difference between the electrostatic charge variations detected by the first and the second electrodes; 
 determining, by the control unit, a quantized signal by processing the electrostatic charge variation signal; 
 determining, by the control unit, an aggregate datum indicative of an aggregation of the carbon dioxide signal, the fuel signal and the electrostatic charge variation signal; and 
 generating, by the control unit and as a function of the aggregate datum, a flame signal indicative of the presence or absence of the flame. 
   
     
     
         12 . The detection method according to  claim 11 , wherein the step of determining the quantized signal comprises:
 calculating a baseline of the electrostatic charge variation signal;   calculating a variability signal by subtracting the baseline from the electrostatic charge variation signal;   determining a normalized signal by comparing the variability signal with a charge variation threshold value, the normalized signal assuming, at each time instant, a first value in response to a corresponding value of the variability signal being lower than the charge variation threshold value, or a second value in response to the corresponding value of the variability signal being greater than or equal to the charge variation threshold value;   for each time instant of the normalized signal, determining a respective clustering interval of the normalized signal, the clustering interval comprising the value of the normalized signal corresponding to the time instant considered and a predefined plurality of values of the normalized signal corresponding to a respective plurality of time instants preceding the time instant considered;   for each clustering interval of the normalized signal, determining which value of the normalized signal, between the first value and the second value, has a greater occurrence in the clustering interval considered; and   generating the quantized signal in such a way that, at each time instant, the quantized signal assumes a respective first value in response to the value of the normalized signal with greater occurrence in the clustering interval of the normalized signal corresponding to the time instant considered being the first value, or assumes a respective second value in response to the value of the normalized signal with greater occurrence in the clustering interval of the normalized signal corresponding to the time instant considered being the second value.   
     
     
         13 . The detection method according to  claim 11 , wherein the step of determining the quantized signal comprises steps of, in succession to each other:
 a. calculating a baseline of the electrostatic charge variation signal;   b. calculating a variability signal by subtracting the baseline from the electrostatic charge variation signal;   c. determining a normalized signal by comparing the variability signal with a charge variation threshold value, the normalized signal assuming, at each time instant, a first value in response to a corresponding value of the variability signal being lower than the charge variation threshold value, or a second value in response to the corresponding value of the variability signal being greater than or equal to the charge variation threshold value, the normalized signal having a number N of samples;   d. generating an augmented normalized signal that comprises the normalized signal, K additional first samples preceding the normalized signal, and K additional second samples successive to the normalized signal, each additional first and second sample assuming the first value of the normalized signal;   e. generating a copy signal equal to the augmented normalized signal;   f. initializing an index i to a value of K;   g. calculating, for an i-th sample of the augmented normalized signal, a respective first cumulative value and a respective second cumulative value, the first cumulative value being indicative of a sum of the samples of the augmented normalized signal preceding the i-th sample and the second cumulative value being indicative of a sum of the samples of the augmented normalized signal that follow the i-th sample;   h. verifying whether the i-th sample is equal to the second value of the normalized signal;   i. in response to the i-th sample not being equal to the second value of the normalized signal, verifying whether the first cumulative value is greater than a threshold cumulative value and whether the second cumulative value is greater than the threshold cumulative value;   j. in response to the i-th sample not being equal to the second value of the normalized signal and both the first cumulative value and the second cumulative value being greater than the threshold cumulative value, updating the i-th sample to the second value of the normalized signal;   k. in response to the i-th sample not being equal to the second value of the normalized signal and at least one of the first cumulative value and the second cumulative value not being greater than the threshold cumulative value, updating the i-th sample to the first value of the normalized signal;   l. in response to the i-th sample being equal to the second value of the normalized signal, verifying whether the first cumulative value or the second cumulative value is greater than the threshold cumulative value;   m. in response to the i-th sample being equal to the second value of the normalized signal and none of the first cumulative value and the second cumulative value being greater than the threshold cumulative value, updating the i-th sample to the first value of the normalized signal;   n. in response to the i-th sample being equal to the second value of the normalized signal and at least one of the first cumulative value and the second cumulative value being greater than the threshold cumulative value, updating the i-th sample to the second value of the normalized signal;   o. verifying whether the index i is lower than the number N;   p. in response to the index i being lower than the number N, updating the index i by adding a unit and repeating steps g-o with the updated index i;   q. in response to the index i not being lower than the number N, verifying whether the copy signal matches the augmented normalized signal;   r. in response to the copy signal not matching the augmented normalized signal, updating the copy signal so that it is equal to the augmented normalized signal and repeating steps f-q with the updated copy signal; and   s. in response to the copy signal matching the augmented normalized signal, generating the quantized signal as a function of the augmented normalized signal.   
     
     
         14 . The detection method according to  claim 11 , wherein:
 the step of determining the aggregate datum comprises determining, at each time instant, a respective set of aggregate datum points defining the aggregate datum in the time instant considered; and   in each set of aggregate datum points, each aggregate datum point is defined by a respective value of the carbon dioxide signal, a respective value of the fuel signal, and a respective value of the electrostatic charge variation signal corresponding to a respective time instant that is equal to the time instant corresponding to the set of aggregate datum points considered or is equal to a time instant between a plurality of time instants preceding the time instant corresponding to the set of aggregate datum points considered, in such a way that the set of aggregate datum points considered is indicative of respective portions of the carbon dioxide signal, the fuel signal and the electrostatic charge variation signal temporally defined by the time instant corresponding to the set of aggregate datum points considered and by the plurality of time instants preceding the time instant corresponding to the set of aggregate datum points considered.   
     
     
         15 . The detection method according to  claim 14 , wherein the step of generating the flame signal comprises, at each time instant:
 calculating a centroid of the respective set of aggregate datum points;   calculating a respective distance of the centroid of the respective set of aggregate datum points from a reference centroid of a reference set of aggregate datum points indicative of the absence of the flame;   comparing the respective distance with a threshold distance; and   assigning to the flame signal a respective first value in response to the respective distance being lower than the threshold distance, or a respective second value in response to the respective distance being greater than or equal to the threshold distance;   the first value of the flame signal being indicative of the absence of the flame and the second value of the flame signal being indicative of the presence of the flame.   
     
     
         16 . The detection method according to  claim 11 , further comprising the steps of:
 verifying, by the control unit and as a function of the electrostatic charge variation signal, a condition of generating a spark for igniting the flame; and   in response to the generating the spark being confirmed and, for a predefined time interval starting from the generating the spark, the flame signal is indicative of the absence of the flame, generating, by the control unit, a spark warning signal.   
     
     
         17 . The detection method according to  claim 16 , wherein the step of verifying the condition of generating the spark comprises verifying whether the electrostatic charge variation signal has a spark generation pattern indicative of the generating of the spark. 
     
     
         18 . A non-transitory computer program product for a control unit of a sensor device, the non-transitory computer program product storing computer instructions for detecting a presence or absence of a flame that, when executed by the control unit, cause the control unit to perform steps of:
 acquiring, through a carbon dioxide sensor, a carbon dioxide signal indicative of a concentration of carbon dioxide in air generated by the flame;   acquiring, through a fuel sensor, a fuel signal indicative of a presence of a combustion of a fuel used to produce the flame;   acquiring, through an electrostatic charge variation sensor including first and second electrodes spaced from each other, an electrostatic charge variation signal indicative of a difference between the electrostatic charge variations generated by the flame detected by the first and the second electrodes;   determining a quantized signal by processing the electrostatic charge variation signal;   determining an aggregate datum indicative of an aggregation of the carbon dioxide signal, the fuel signal and the electrostatic charge variation signal; and   generating, as a function of the aggregate datum, a flame signal indicative of the presence or absence of the flame.   
     
     
         19 . The non-transitory computer program product according to  claim 18 , wherein the step of determining the quantized signal comprises:
 calculating a baseline of the electrostatic charge variation signal;   calculating a variability signal by subtracting the baseline from the electrostatic charge variation signal;   determining a normalized signal by comparing the variability signal with a charge variation threshold value, the normalized signal assuming, at each time instant, a first value in response to a corresponding value of the variability signal being lower than the charge variation threshold value, or a second value in response to the corresponding value of the variability signal being greater than or equal to the charge variation threshold value;   for each time instant of the normalized signal, determining a respective clustering interval of the normalized signal, the clustering interval comprising the value of the normalized signal corresponding to the time instant considered and a predefined plurality of values of the normalized signal corresponding to a respective plurality of time instants preceding the time instant considered;   for each clustering interval of the normalized signal, determining which value of the normalized signal, between the first value and the second value, has a greater occurrence in the clustering interval considered; and   generating the quantized signal in such a way that, at each time instant, the quantized signal assumes a respective first value in response to the value of the normalized signal with greater occurrence in the clustering interval of the normalized signal corresponding to the time instant considered being the first value, or assumes a respective second value in response to the value of the normalized signal with greater occurrence in the clustering interval of the normalized signal corresponding to the time instant considered being the second value.   
     
     
         20 . The non-transitory computer program product according to  claim 18 , wherein:
 the step of determining the aggregate datum comprises determining, at each time instant, a respective set of aggregate datum points defining the aggregate datum in the time instant considered; and   in each set of aggregate datum points, each aggregate datum point is defined by a respective value of the carbon dioxide signal, a respective value of the fuel signal, and a respective value of the electrostatic charge variation signal corresponding to a respective time instant that is equal to the time instant corresponding to the set of aggregate datum points considered or is equal to a time instant between a plurality of time instants preceding the time instant corresponding to the set of aggregate datum points considered, in such a way that the set of aggregate datum points considered is indicative of respective portions of the carbon dioxide signal, the fuel signal and the electrostatic charge variation signal temporally defined by the time instant corresponding to the set of aggregate datum points considered and by the plurality of time instants preceding the time instant corresponding to the set of aggregate datum points considered.