FR2830655A1 - Carbon monoxide detector and detection process where the detector automatically shuts down and restarts the associated carbon monoxide generator N times before shutting it down definitively - Google Patents

Abstract

The detector contains means (10, 17) of automatically deactivating an associated carbon monoxide (CO) generator when a parameter reaches a set value and restarting it automatically when the parameter drops below this value. This is repeated N times (N more than = 1) before the generator is deactivated so it requires manual restarting and the people exposed to the CO are informed that this has been done The generator is deactivated so it requires manual restarting if the parameter reaches the set value N+1 times in a predetermined time period L. The measured parameter is a quantity of carbon monoxide produced in the time, or represents a quantity of carboxyhaemaglobin. The means of measuring this parameter comprises a means (12) of measuring the concentration of carbon monoxide in the environment in which the device is placed and means (10) of calculating the quantity of carboxyhaemaglobin as a function of the measured CO concentration. In addition the device has means of reactivating the generator in response to manual intervention, comprising a button (18) to press within a set time. An alarm (15) is sounded each time the threshold value is passed. N is equal to 2 and the predetermined time lapse L is about 4 hours. An Independent claim is also included for a process for detecting carbon monoxide using such a device as described above.

Description

<Desc / Clms Page number 1>

 The present invention relates to a device for detecting carbon monoxide (CO) intended to be associated with an apparatus generating carbon monoxide. By carbon monoxide generating apparatus means an apparatus which emits, or is capable of emitting, carbon monoxide, in particular when it becomes defective. As examples of apparatus of this type, mention may be made of combustion apparatuses such as boilers, water heaters, stoves, etc.

 More particularly, the present invention relates to a device designed to measure a level of carbon monoxide in the environment in which it is placed, and, in the event of an alert threshold being exceeded, trigger an alarm and automatically shut down the associated carbon monoxide generating device.

 Carbon monoxide is a colorless, odorless, and, in general, undetectable gas by human senses. Formed during your incomplete combustion of carbonaceous substances (hydrocarbons, coal, wood), it is very toxic as soon as its concentration reaches a certain threshold. In a confined environment, such as a house or apartment, its dangerousness is therefore very high.

 Carbon monoxide enters the blood system from the lungs and combines with hemoglobin, 240 times more easily than oxygen, to form carboxyhemoglobin (COHb). As carbon monoxide builds up in the blood, the body is increasingly deprived of oxygen. When the carboxyhemoglobin saturation reaches a value of 10 to 30%, the following symptoms may appear: headache, weakness, nausea, confusion, disorientation and visual disturbances. In the case of more prolonged exposures leading to carboxyhemoglobin levels of between 30 and 50%, symptoms of the type dyspnea exertion, increase in the

<Desc / Clms Page number 2>

 respiratory and heart rate and syncope. When the carboxyhemoglobin level exceeds 50%, there may be coma, convulsions and ultimately cardiac and respiratory arrest. In addition, carbon monoxide poisoning is frequently accompanied by complications, such as immediate death, myocardial damage, hypotension, arrhythmia, pulmonary edema, or neuropsychiatric sequelae.

 Partly because of its colorless and odorless nature, carbon monoxide becomes toxic without the exposed person being able to notice it. The role of a carbon monoxide detector is to warn the occupant of a dwelling, generally by an audible and visual alarm, of an accumulation of carbon monoxide in his environment, to allow him to react before be exposed to a significant risk. When the alarm is triggered, the occupant knows that measures must be taken immediately, namely, ventilate the premises by opening the windows wide, and go outside.

 Several types of carbon monoxide detectors are currently on the market. These detectors are generally content to measure and display the carbon monoxide concentration on a screen, and to trigger an alarm if a threshold is exceeded.

 Also known, from document WO 01/33213, is a carbon monoxide detector capable of measuring the concentration of carbon monoxide in the environment in which it is found, and of estimating a corresponding level of carboxyhemoglobin. This detector is also designed to shut down the associated carbon monoxide generating device when an alert threshold has been exceeded.

 None of the carbon monoxide detectors known to date, however, is capable of identifying, even roughly, the emitting source of carbon monoxide. In fact, if the emission of carbon monoxide responsible for triggering the alarm can come from

<Desc / Clms Page number 3>

 the device associated with the detector, it can also be the case, for example, of another domestic device located in the same apartment, house or building, of an obstructed chimney or even of external pollution, in particular in cold weather and dry. On the other hand, cigarette smoke alone can contain enough carbon monoxide to trigger the alarm.

 When the alarm is triggered, the occupant's reflex, once the immediate precautionary measures have been taken, is to call the company in charge of maintaining the carbon monoxide generating device, which will have to send a technician to verify the proper functioning of the device or, at best, spend time on the phone with the occupant to try to identify the emitting source. Each nuisance alarm triggering causes the maintenance company a significant loss of time.

 It is understood, in this context, that there is a need for a carbon monoxide detector capable of verifying whether the source emitting carbon monoxide, responsible for exceeding the alert threshold, is indeed the associated device. The present invention aims to fill this need.

 To this end, there is provided a device for detecting carbon monoxide intended to be associated with an apparatus generating carbon monoxide, said device comprising: - means for measuring a parameter dependent on the amount of carbon monoxide present in the environment in which the device is placed, and being characterized in that it further comprises: - means for implementing at least N times the succession of following steps, where N is a predetermined integer at least equal to 1:

<Desc / Clms Page number 4>

 automatically deactivate the carbon monoxide generating device when the value of the measured parameter exceeds a predetermined threshold, and. then automatically reactivating the carbon monoxide generating device when the value of the measured parameter falls below the predetermined threshold, - a means for permanently deactivating the carbon monoxide generating device, that is to say deactivating it '' in such a way that only a manual intervention can reactivate it, if, following said succession of steps implemented N times, the value of the measured parameter again exceeds the predetermined threshold within a predetermined period of time from automatic device deactivation step, in the case where N is equal to 1, or the first automatic device deactivation step, in the case where N is greater than 1, and - a means for informing the or people exposed to carbon monoxide from the final deactivation of the carbon monoxide generating device.

 Thus, the detection device according to the present invention automatically reactivates the carbon monoxide generating device when, after a first deactivation, the measured parameter falls below the alert threshold. This passage below the alert threshold will occur, for example, in one of the following situations, which may possibly accumulate: - the emission of carbon monoxide having caused the alert threshold to be exceeded comes from the device associated with the detection device; disabling the device will cause a drop in the carbon monoxide concentration; - after deactivation of the device, the occupant ventilates the premises, which lowers the concentration of carbon monoxide;

<Desc / Clms Page number 5>

 - the emission of carbon monoxide which led to the exceeding of the alert threshold comes from a point source, such as a cigarette, the effects of which disappear or diminish over time.

 If, after reactivation of the device associated with the detection device, the value of the measured parameter again exceeds the alert threshold, the device is deactivated again, and so on.

 However, if, after a number N of deactivation (s) and reactivation (s), a (N + 1) th deactivation occurs within a predetermined period of time from the first deactivation, for example one or more hours, we may consider that the source emitting carbon monoxide responsible for exceeding the alert threshold is the device associated with the detection device. For security reasons, this device will then be permanently deactivated or, in other words, deactivated in such a way that only manual intervention, typically intervention by a technician from the device maintenance company and / or the detection device, can reactivate it.

 Until the device is finally deactivated, it can be assumed that the device is operating normally and that the source emitting the carbon monoxide in question must be sought elsewhere.

 When the carbon monoxide generating device is permanently deactivated, the detection device according to the invention informs the occupant of the premises, for example by means of a display.

The occupant knows at this time that the problem comes from the device and that he can ask the maintenance company to send a technician.

 Preferably, the number N is chosen equal to 2, and the predetermined period of time has a duration of approximately 4 hours.

 Advantageously, the parameter measured is a rate of time-weighted carbon monoxide, preferably representative of a rate

<Desc / Clms Page number 6>

 carboxyhemoglobin. In the latter case, the measuring means typically comprises a means for measuring the concentration of carbon monoxide in the environment in which the device is placed, and a means for calculating the level of carboxyhemoglobin as a function of the concentration of carbon monoxide measured.

 Advantageously, the device according to the invention further comprises means for reactivating the carbon monoxide generating apparatus in response to said manual intervention, which means comprises, for example, a button to be actuated during a predetermined time interval. In practice, we will make sure that the user does not know how to reactivate the device manually, in order to leave it to the only maintenance technician to restart the faulty device.

 Typically, the device according to the invention further comprises means for triggering an alarm each time the value of the measured parameter exceeds the predetermined threshold. The alarm can be audible or visual, preferably at least audible.

 The present invention also relates to a method for detecting carbon monoxide, in which a parameter dependent on the amount of carbon monoxide present in the liquid is measured by means of a detection device associated with a carbon monoxide generating apparatus. environment in which the device is placed, characterized in that it further comprises the steps consisting in: - implementing at least N times the following succession of steps, where N is a predetermined integer at least equal to 1 : automatically deactivate the carbon monoxide generating device when the value of the measured parameter exceeds a predetermined threshold, and. then automatically reactivate the carbon monoxide generating device when the value of the measured parameter

<Desc / Clms Page number 7>

 goes back below the predetermined threshold, - permanently deactivate the carbon monoxide generating device, that is to say deactivate it in such a way that only manual intervention can reactivate it, if, following said succession of 'steps implemented N times, the value of the measured parameter again exceeds the predetermined threshold within a predetermined period of time from the automatic device deactivation step, in the case where N is equal to 1, or the first step of automatic deactivation of the device, in the event that N is greater than 1, and - inform the person or persons exposed to carbon monoxide of the definitive deactivation of the device producing carbon monoxide.

 Other characteristics and advantages of the present invention will appear on reading the following detailed description of several embodiments of the invention, made with reference to the accompanying drawings, in which: - Figure 1 is a block diagram of a device for detecting carbon monoxide according to the invention, associated with an apparatus generating carbon monoxide; - Figures 2,3 and 4 are flowcharts of a method of detecting carbon monoxide implemented by the device illustrated in Figure 1; FIGS. 5A, 5B and 5C show configurations in which, respectively, three, two and an alarm triggering take place within a predetermined period of time of duration L; and - Figure 6 is a timing diagram showing the state of the carbon monoxide generating apparatus in a typical alarm sequence of the present invention.

 Referring to Figure 1, a monoxide detection device

<Desc / Clms Page number 8>

 1 according to the invention mainly comprises a microcontroller 10, an electrical supply circuit 11, a carbon monoxide sensor 12 connected to the microcontroller 10 via an analog / digital converter 13, a clock 14, an audible warning device (buzzer) 15, a liquid crystal display 16, a relay 17 and an unlocking switch button 18.

 The carbon monoxide sensor 12 is a conventional type sensor, for example a semiconductor. It is designed to detect the presence of carbon monoxide in the environment in which it is placed, and to produce analog signals representative of the concentration of carbon monoxide in this same environment. These analog signals are digitized by the converter 13, which supplies the digital signals thus obtained to the microcontroller 10.

 The detection device according to the invention is intended to be connected to an apparatus generating carbon monoxide 2 (partially shown in FIG. 1), that is to say an apparatus which emits, or is capable of emitting, carbon monoxide. The device 2 is for example a boiler, a water heater or a stove. The detection device 1 is connected to the mains (alternative electrical network) via the device 2. More particularly, a neutral conductor 11a and a phase conductor 11b connect the supply circuit 11 of the device 1 respectively to a neutral conductor 20a and a phase conductor 20b connected directly to the mains and which supply the device 2 with alternating current.

 The neutral conductor 20a consists of a first part 20c which connects a first terminal 17a of the relay 17 to the sector, and a second part 20d which connects a second terminal 17b of the relay 17 to a supply circuit 21 of the device 2 to which the phase conductor 20b is also connected. When the relay 17 is open, as shown in Figure 1,

<Desc / Clms Page number 9>

 the conductor parts 20c and 20d are not connected to each other, so that the device 2 is not supplied with electric current. When the relay 17 is closed, the conductor parts 20c and 20d are connected together, and the device 2 is supplied. The openings and closings of the relay 17 are controlled by the microcontroller 10.

 In accordance with the present invention, the microcontroller 10 of the detection device 1 is programmed to implement the method illustrated in FIGS. 2 to 4, and described below.

 With reference to FIG. 2, in a first step E1 of the method according to the invention, the sensor 12 conventionally measures the presence of carbon monoxide in the air. This measurement is carried out periodically, for example every 30 seconds. As indicated above, the analog signals produced by the sensor 12 are converted into digital signals by the converter 13, then supplied to the microcontroller 10 which calculates the volume concentration in ppm of carbon monoxide. From this carbon monoxide concentration, and using the signals delivered by the clock 14, the microcontroller 10 also calculates a time-weighted carbon monoxide level, preferably corresponding to an estimate of the level of carboxyhemoglobin (COHb ) in the blood of the exposed person (s) (step E2). Several formulas exist in the state of the art which allow this carboxyhemoglobin level to be estimated. As an example, one of them, based on the American standard UL 2034, is cited in document WO 01/33213.

 The level of carboxyhemoglobin, more than the concentration of carbon monoxide, makes it possible to measure the risk for the person or persons exposed. Indeed, the degree of carbon monoxide poisoning is a function not only of the concentration of carbon monoxide in the breathed air, but also of the time of exposure. A

<Desc / Clms Page number 10>

 prolonged exposure to a low concentration of carbon monoxide can be as damaging as a short exposure to a high concentration of carbon monoxide. The various standards currently in existence, such as the aforementioned American standard UL 2034 or the European standard EN 50291, define alert thresholds which depend both on the carbon monoxide level and on the exposure time.

 Once the carboxyhemoglobin level has been calculated, the microcontroller 10 compares this rate with a predetermined alert threshold, fixed for example at 10% (step E3). If the carboxyhemoglobin level is below the alert threshold, the microcontroller returns to step E1 to measure the presence of carbon monoxide in the air, 30 seconds after the first measurement. If, on the other hand, in step E3, the carboxyhemoglobin level reaches or exceeds the alert threshold, the microcontroller proceeds to a next step E4.

 In step E4, the audible warning device 15 is activated to trigger an alarm. At this time, the occupant of the premises must react, and in particular open the windows and go outside. The instant t of the triggering of 1 "alarm, represented by a date and a time, is stored in memory in the microcontroller 10 (step E5).

 In a next step E6, the microcontroller counts the number of alarm triggers which have taken place during the period of time [t-L, t], where L is a predetermined duration. If, as shown in FIG. SA, a predetermined number M (taken equal to 3 in the example of FIGS. SA, 5B and 5C) of triggers DL have taken place during this period of time (step E7), or, in d In other words, a predetermined number N = M-1 of DL triggers have taken place in the period of time [tL, t [, it can be considered that device 2 is responsible for the increase in the level of carbon monoxide in the air. In this case, steps E8 to E17 are implemented (see reference B and Figure 4). These steps will be described later.

<Desc / Clms Page number 11>

 If, on the other hand, it is determined in step E7 that the number of trips DL during the period of time [tL, t] is less than the number M, as illustrated in FIGS. 5B and 5C, then steps E18 to E25 are executed (see reference A and figure 3).

 In practice, the predetermined duration L is preferably chosen to be 4 hours, and the predetermined number M is preferably fixed at 3 (N = 2).

 In step E18, the relay 17 is open to cut the electrical supply to the device 2 and thus deactivate the latter. In step E19, the message ALARM m is displayed on the display 16, m being the number of alarm triggers DL determined in step E6.

 In the following steps E20 and E21, the microcontroller measures the level of carbon monoxide, 30 seconds after the last measurement carried out in step E1, then estimates the level of carboxyhemoglobin of the person or persons exposed, in the same manner as in step E2.

 In the next step E22, the carboxyhemoglobin level thus estimated is compared to the alert threshold. If this rate is still greater than or equal to the alert threshold, we return to step E20 for a new measurement of the carbon monoxide level, 30 seconds after the previous one.

 If, on the other hand, the carboxyhemoglobin level has returned below the alert threshold, then the audible warning device 15 is deactivated in the next step E23, the ALARM m message is erased on the display 16 (step E24) and the relay 17 is closed to supply the device 2 again and thus reactivate it (step E25). It will be noted that the audible alarm can also be turned off at any time by the user, by means of a button provided for this purpose (not shown) on the device 1. Also, by pressing another key ( not shown), the user can read on the display 16 the latest respective values of the concentration in ppm of carbon monoxide and of the rate of carboxyhemoglobin.

<Desc / Clms Page number 12>

 The lowering of the carboxyhemoglobin level making it possible to pass from stage E22 to stage E23 will occur for example in the case where, in accordance with the recommendations, the occupant of the contaminated place will have opened the windows after the triggering of the alarm . Another case, which can be cumulated with the previous one, is that where the increase in the carboxyhemoglobin level was indeed due to device 2, so that its cut-off in step E18, by reducing the carbon monoxide level , will also have reduced the level of carboxyhemoglobin.

 After closing the relay 17 in step E25, the microcontroller returns to step El, as shown by the reference C.

 Steps E8 to E17, implemented when it is determined in step E7 that the source of carbon monoxide in question is the apparatus 2, are now described.

 In step E8, the microcontroller 10 opens the relay 17 to deactivate the device 2. In step E9, the microcontroller controls the display on the display 16 of the statement ALARM M, namely, in the preferred case where M is 3, ALARM 3.

 In the following steps E10 and E11, the microcontroller, associated with the sensor 12, measures the level of carbon monoxide and the corresponding carboxyhemoglobin level in the same way as in steps E1 and E2.30 seconds after the last measurement. If, in step E12, it is determined that the carboxyhemoglobin level is still greater than or equal to the alert threshold, the microcontroller returns to step E10. If, in step E12, the carboxyhemoglobin level has dropped below the alert threshold, the microcontroller goes to step E13, where it deactivates the audible warning device 15 if this has not already been done by the user by means of the button provided for this purpose.

 Then, the microcontroller goes into a waiting state (step E14) until the unlocking button 18 is pressed.

<Desc / Clms Page number 13>

 continuously during a predetermined time interval T, chosen for example equal to 10 seconds. This waiting state amounts to making the deactivation of the device 2 definitive. In the context of the present invention, the expression definitive deactivation means that the device 2 is deactivated in such a way that only manual intervention, knowing that the button 18 is pressed during the time interval T, can reactivate it. In practice, the actuation of the button 18 will be carried out by the maintenance technician, once the cause of the emission of carbon monoxide has been detected and the appliance 2 repaired. The user will not be aware of the function of button 18, nor of how it must be actuated. The actuation of the button 18 during the time interval T leads to the implementation of steps E1S to E17, which will be described later.

 Although this is not shown in FIG. 4, the microcontroller 10 associated with the sensor 12, continues, during step E14, to periodically measure the levels of carbon monoxide and of carboxyhemoglobin and to store them in memory. These rates are displayed on the display 16, temporarily replacing the mention ALARM M or in addition to this mention, if the user presses the key provided for this purpose.

 In step E15, the microcontroller erases the indication ALARM M on the display 16. In step E16, it erases from the corresponding memory the various alarm triggering records stored during the preceding steps E5. Then, in step E17, the microcontroller closes the relay 17 to restart the device 2, then returns to step El as shown by the reference D.

 FIG. 6 shows, by way of summary, a typical alarm sequence of the present invention according to the preferred embodiment, in which, in particular, M is equal to 3 (N = 2). At a time tl, a first

<Desc / Clms Page number 14>

 alarm is triggered and the ALARM 1 indication is displayed on the display 16. At an instant t2, after reactivation of the device 2, a second alarm is triggered and the ALARM 2 indication is displayed. At an instant t3, after a period of time LP lasting from instant tl, a new alarm is triggered. As, in the example of FIG. 6, the duration LP is less than the duration L, that is to say, in other words, that the instant t3 is in the period of time of duration L from the moment of the first trip tl, the display 16 displays the ALARM 3 indication and the device 2 is permanently deactivated.

 When an alarm is triggered, the user can call the maintenance company. This will first ask him which alarm number is displayed on the display 16. If the alarm that is displayed is an ALARM 1 or an ALARM 2, the maintenance company will advise the user in particular, after of course having reminded him of the immediate precautions to take, to turn off other combustion appliances in his home, and, if he is smoking, to put out his cigarette. If the alarm which is displayed on the display 16 is an ALARM 3, the maintenance company will send a technician to check the device 2 and possibly repair or replace it.

 The present invention is not limited to the embodiments described above. Those skilled in the art will understand for example that, although advantageous, the measurement of the carboxyhemoglobin level as carried out by the microcontroller 10 in association with the sensor 12 is not compulsory. The invention can be implemented by measuring, more generally, a parameter depending on the amount of carbon monoxide present in the air.

 It will also be clear to a person skilled in the art that means other than that comprising a button to be actuated for a predetermined period of time can be used to unlock the

<Desc / CRUD Page number 15>

 microcontroller 10 and manually reactivate the carbon monoxide generating device 2.

Claims (12)

 the device, in the case where N is equal to 1, or in the first step of automatic deactivation of the device, in the case where N is greater than 1, and - means (10,16) for informing the or people exposed to carbon monoxide from the final deactivation of the generator

CLAIMS 1. Device (1) for detecting carbon monoxide intended to be associated with an apparatus (2) generating carbon monoxide, said device comprising: - means (10, 12, 13) for measuring a parameter dependent on the quantity of carbon monoxide present in the environment in which the device is placed, and being characterized in that it further comprises: - a means (10,17) for implementing at least N times the succession of steps following, where N is a predetermined integer at least equal to 1: automatically deactivating the carbon monoxide generating apparatus (2) when the value of the measured parameter exceeds a predetermined threshold, and. then automatically reactivating the carbon monoxide generating device (2) when the value of the measured parameter falls below the predetermined threshold, - means (10,17) for definitively deactivating the carbon monoxide generating device (2) , i.e. deactivate it in such a way that only manual intervention can reactivate it, if, following said succession of steps implemented N times, the value of the measured parameter again exceeds the predetermined threshold within a predetermined period of time (L) from the stage of automatic deactivation of <Desc / Clms Page number 17>  carbon monoxide. 2. Device according to claim 1, characterized in that said parameter is a rate of carbon monoxide weighted in time. 3. Device according to claim 1 or 2, characterized in that said parameter is representative of a carboxyhemoglobin level. 4. Device according to claim 3, characterized in that said measuring means comprises: - a means (12) for measuring the concentration of carbon monoxide in the environment in which the device is placed, and - a means (10) to calculate the carboxyhemoglobin level as a function of the measured carbon monoxide concentration. 5. Device according to any one of claims 1 to 4, characterized in that it further comprises means (10,18) for reactivating the apparatus generating carbon monoxide in response to said manual intervention. 6. Device according to claim 5, characterized in that said means for reactivating the carbon monoxide generating apparatus in response to said manual intervention comprises a button (18) to be actuated during a predetermined time interval. 7. Device according to any one of claims 1 to 6, characterized in that it further comprises means (10,15) for triggering an alarm each time the value of the measured parameter exceeds the predetermined threshold. <Desc / Clms Page number 18> 8. Device according to any one of claims 1 to 7, characterized in that the number N is equal to 2, and the predetermined period of time (L) has a duration of approximately 4 hours. 9. Method for detecting carbon monoxide, in which a parameter, depending on the amount of carbon monoxide present, is measured by means of a detection device (1) associated with an apparatus (2) generating carbon monoxide in the environment in which the device is placed, characterized in that it further comprises the steps consisting in: - implementing at least N times the succession of following steps, where N is a predetermined whole number at least equal to 1: automatically deactivate the carbon monoxide generating device (2) when the value of the measured parameter exceeds a predetermined threshold, and. then automatically reactivate the carbon monoxide generating device (2) when the value of the measured parameter falls below the predetermined threshold, - permanently deactivate the carbon monoxide generating device (2), i.e. deactivate it in such a way that only manual intervention can reactivate it, if, following said succession of steps implemented N times, the value of the measured parameter again exceeds the predetermined threshold within a predetermined period of time (L ) from the automatic device deactivation step, in the case where N is equal to 1, or from the first automatic device deactivation step, in the case where N is greater than 1, and - inform the person (s) exposed to carbon monoxide of the final deactivation of the apparatus producing carbon monoxide <Desc / Clms Page number 19>  carbon. 10. Method according to claim 9, characterized in that said parameter is a time-weighted carbon monoxide content. 11. Method according to claim 9 or 10, characterized in that said parameter is representative of a carboxyhemoglobin level. 12. Method according to any one of claims 9 to 11, characterized in that an alarm is triggered each time the value of the measured parameter exceeds the predetermined threshold.