EP0913644A1 - Appareil de combustion - Google Patents

Appareil de combustion Download PDF

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Publication number
EP0913644A1
EP0913644A1 EP97930779A EP97930779A EP0913644A1 EP 0913644 A1 EP0913644 A1 EP 0913644A1 EP 97930779 A EP97930779 A EP 97930779A EP 97930779 A EP97930779 A EP 97930779A EP 0913644 A1 EP0913644 A1 EP 0913644A1
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EP
European Patent Office
Prior art keywords
carbon monoxide
exhaust gas
density
combustion
danger
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP97930779A
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German (de)
English (en)
Inventor
Naoyuki Gastar Co. Ltd. TAKESHITA
Toshihisa Gastar Co. Ltd. SAITO
Masanori Gastar Co. Ltd. ENOMOTO
Masato Gastar Co. Ltd. KONDO
Toru Gastar Co. Ltd. IZUMISAWA
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Gastar Co Ltd
Original Assignee
Gastar Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP20664096A external-priority patent/JP3727418B2/ja
Priority claimed from JP20664196A external-priority patent/JPH1030817A/ja
Priority claimed from JP20901796A external-priority patent/JPH1038270A/ja
Priority claimed from JP21801796A external-priority patent/JP3691599B2/ja
Priority claimed from JP28641896A external-priority patent/JP3810153B2/ja
Application filed by Gastar Co Ltd filed Critical Gastar Co Ltd
Publication of EP0913644A1 publication Critical patent/EP0913644A1/fr
Withdrawn legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/003—Systems for controlling combustion using detectors sensitive to combustion gas properties
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/24—Preventing development of abnormal or undesired conditions, i.e. safety arrangements

Definitions

  • the present invention relates to a combustion apparatus, and in particular to a combustion apparatus for detecting the presence of carbon monoxide gas (hereinafter referred to as CO) and for performing an appropriate safety operation.
  • CO carbon monoxide gas
  • Fig. 1 is a diagram showing the specific structure of a water heater which is commonly called a combustion apparatus.
  • Fig. 2 is a diagram showing an operating configuration when a water heater has been installed inside a building.
  • a water heater 1 is provided with indoor air by a fan 2 which, as it rotates, draws air in through a filter 3 and feeds it to a burner 4 whereat a gas supplied as fuel is burned to heat a heat exchanger 5, while at the same time water is circulated through the heat exchanger 5, is heated, and is then conveyed to a desired location, such as a kitchen, via a hot water pipe connected to the outlet port of the heat exchanger 5.
  • the combustion which takes place in the water heater 1 is controlled by a control unit 6, which is connected to a remote controller 7.
  • a flue connector 8 mounted on the water heater 1 is fitted into the proximal end of a flue 10 whose distal end is extended to the outside of the building, so that exhaust gas generated by the combustion fed by indoor air are discharged to the outside.
  • a method is employed, as is shown in Fig. 2, whereby a hole is formed in a wall in the vicinity of the water heater 1 and the flue 10 is passed through the hole in the wall so that it is projected outward externally.
  • a method can be employed, as is indicated by the broken lines, whereby lengths of piping are coupled together to form a flue and are installed above the ceiling, the distal end of the flue projecting outward externally from above the ceiling.
  • CO gas carbon monoxide gas
  • exhaust gas is discharged to the outside via the flue 10, and there are generally no leaks indoors.
  • the CO gas can leak out indoors through the gap or the hole (or through the gap in the ceiling when the flue 10 is mounted above the ceiling). Then, when the CO density in the indoor air has reached a density that is dangerous for human beings, gas poisoning occurs.
  • CO poisoning occurs when the hemoglobin in the blood of a person combines with the CO, and produces the symptoms shown in Fig. 3 in consonance with the percentage of the hemoglobin which has combined with CO (hereinafter refereed to as the hemoglobin CO density).
  • Fig. 4 is a graph showing the relationship of the density of the CO in the air and the hemoglobin CO density. In Fig. 4, when a person breathes air having a CO density of 0.2% for two hours, the hemoglobin CO density reaches approximately 64%.
  • a CO sensor 11 is installed at the vented side of the water heater 1.
  • the danger time is given in advance corresponding to the CO density detected by the CO sensor 11 in case that the exhaust gas leaks indoors.
  • a safety countermeasure is instituted, such as the generation of an alarm or the stopping of the combustion process.
  • the density of the CO in the air (hereinafter referred to as the indoor CO density), which provides the reference value employed for calculating the danger time, is obtained in accordance with the CO density of the exhaust gas which is discharged by the combustion apparatus.
  • the indoor CO density in the room into which the CO gas is leaked depends not only on the CO density of the exhaust gas but also on a combustion condition which will be described later.
  • the indoor CO density depends on the combustion capability of a combustion apparatus or on the volume of the exhaust gas. Specifically, for the combustion process performed by the water heater 1, the air flow rate of the fan 2 is controlled in order to adjust it so that it corresponds to the combustion capability, i.e., to adjust it in accordance with the volume of gas which is supplied. Therefore, the discharge volume (the flue volume) for each exhaust gas hour unit is varied in accordance with the combustion capability. When there are indoor exhaust gas leaks, the volume of the gas leaked differs, even though the CO density detected by the CO density sensor is the same. As the combustion capability increases or the discharge volume grows, the indoor CO contamination becomes worse.
  • the danger time for the individual CO densities is set while taking into account a combustion process by the maximum combustion capability having the greatest danger for CO.
  • the combustion apparatus is controlled by limiting its operation to a range extending from its minimum combustion capability to its maximum combustion capability.
  • the danger time which corresponds to the CO density detected by the CO sensor 11 is set in accordance with data obtained while the device was being operated at its maximum capability.
  • the indoor CO density does not constitute a danger to human beings, it is assumed that the indoor state has reached a point that the danger of CO poisoning does exist, and the combustion operation is stopped.
  • the indoor CO density depends on the volume of the room wherein the combustion apparatus is installed. That is, when CO gas whose density in the exhaust gas is constant is discharged into a space, the indoor CO density differs in accordance with the volume of the space.
  • the danger time is reached corresponds to each CO density is set based on a specific indoor volume. If the combustion apparatus is installed in a larger room for which the indoor volume is greater than that which has been set, the predetermined danger time is reached may reach before the CO density constitutes a danger to human beings. In this case, although there is no danger of CO poisoning, the combustion operation is stopped.
  • the indoor CO density depends on the type of gas supplied for the combustion process. Specifically, since the gas type employed for the combustion process for the water heater 1 may vary in accordance with the local area, normally, a gas type select switch (not shown) is provided for the water heater 1. At the time the water heater 1 is shipped, the gas type for a specific destination is selected using the gas type select switch, and the combustion capability of the water heater 1 is adjusted in accordance with the gas type.
  • the volume of the exhaust gas which are generated during each unit hour also differs in accordance with the combustion of the gas used for fuel. Therefore, when there is an indoor gas leak, the degree of CO contamination produced by the leak differs, even though the level of the CO detected by the CO sensor 11 is the same, and the indoor CO contamination is increased when a gas type generates a larger volume of exhaust gas per unit hour.
  • the danger time can be shortened by using as a reference the gas type which generates the largest volume of exhaust gas per unit hour.
  • a safety operation such as the stopping of the combustion, is performed before reaching dangerous state for CO poisoning.
  • the indoor CO density varies in accordance with the structure of the air-intake and flue pipes of the combustion apparatus, i.e., in accordance with either a double pipe structure or a dual pipe structure.
  • the double pipe structure and the dual pipe structure will now be described.
  • Figs. 5 and 6 are schematic diagrams showing combustion apparatus which the respectively have a double pipe structure and a dual pipe structure.
  • an air intake pipe 401 and a flue pipe 402 are provided in a double structure, and an adapter 403 is fixed at the distal end of the double air-intake and flue pipe.
  • a ventilation unit 404 of a different type is connected to the adapter 403.
  • the appliance shown in Fig. 5 has a double pipe structure wherein the double structure comprised by the air intake pipe 401 and the flue pipe 402 is formed for the ventilation unit 404.
  • These pipes 401 and 402 of the ventilation unit 404 are installed, for example, above the ceiling, and are extended to the outside.
  • a ventilation unit 404 for the water heater shown in Fig. 6 has a dual ventilation pipe structure wherein an air intake pipe 401 and a flue pipe 402 are separately provided. Whether to employ the double ventilation pipe structure or the dual ventilation pipe structure is determined in accordance with the condition of the installation site selected for the water heater.
  • the adapter 403 is provided on the appliance side in order to cope with both ventilation pipe structures, and either the ventilation unit 404 for the double pipe structure or the ventilation unit 404 for the dual pipe structure can be detachably connected to the adapter 403.
  • a gas solenoid valve 414 opens and closes the gas pipe 407, a proportioning valve 415 controls the volume of gas which is supplied gas in consonance with the degree to which the valve 415 is opened.
  • a CO sensor 416 detects the density of the CO in the exhaust gas.
  • the present inventor performed experiments to acquire data on an indoor CO contamination state caused by the leakage of exhaust gas at a defective indoor portion, such as when a gap is formed or when pipe segments are disengaged at a joint in the flue pipe 402 (tubular segments are connected together to form the air intake pipe 401 and the flue pipe 402 which project outward externally). Examples of the results obtained are shown in Figs. 7 and 8.
  • Fig. 7 are shown example results obtained with the double ventilation pipe structure.
  • the air intake pipe is also damaged at the same place and that this causes the gas leakage.
  • indoor air is fed through the air intake pipe 401 to the burner 406. That is, as exhaust gas is leaked indoors, the indoor oxygen density is reduced, and, since the indoor air is repeatedly fed to the burner 406, air having a progressively lower oxygen content is supplied to the burner 406.
  • incomplete combustion occurs, and as time elapses, the indoor oxygen density is greatly reduced. Accordingly, deterioration of the combustion state gradually worsens, due to the lack of oxygen in the air supplied to the burner 406, and the volume of CO gas generated becomes larger and is accompanied by a drastic increase in the indoor CO contamination.
  • Fig. 7(a) is shown the time-transient change in the indoor oxygen density
  • Fig. 7(b) is shown the time-transient change in the CO density in exhaust gas
  • Fig. 7(c) is shown the time-transient change in the indoor CO density.
  • the solid lines in the graphs indicate the readings obtained when the combustion capability was 40000 Kcal/h
  • the broken lines indicate the readings obtained when the combustion capability was 30000 Kcal/h
  • the chained lines indicate the reading obtained when the combustion capability was 10000 Kcal/h.
  • the indoor CO contamination is greatly affected by a lack of indoor oxygen, which is caused by the leakage of exhaust gas indoors, and the indoor oxygen density varies greatly in accordance with the combustion capability. Therefore, it is preferable that the indoor CO contamination be evaluated while taking the combustion capability into consideration.
  • the CO contamination mechanism differs depending on the ventilation structure provided for the water heater. Therefore, with the conventional method, whereby the indoor CO contamination state is evaluated as constituting a constant condition, without any consideration being given to the structure of the ventilation system, or regardless of what ventilation pipe configuration is employed, it is difficult to precisely evaluate indoor CO contamination, and accordingly, the reliability of the CO safety operation is lost.
  • the ER value is defined as t/T, where t denotes a constant time unit during which a specific CO density is detected in the air to which a human being is exposed, and T denotes a period of time that the density of the CO in hemoglobin reaches a predetermined density (e.g., 25%) which has an effect on the human body.
  • a predetermined density e.g. 25%
  • the weighted value for each time unit can be obtained by calculating the ratio of the unit time t to the time T, which corresponds to the CO density.
  • the sum of the ER values is defined as the TR value. When the TR value reaches 1, it is assumed that the density of the CO in hemoglobin reaches a specific dangerous density.
  • the predetermined dangerous density is set to an arbitrary value in accordance with the environment wherein the combustion apparatus is installed, and may be set low, for example, 10%, in order to prevent the occurrence of CO poisoning, and employed for determining a corresponding ER value.
  • Fig. 9 is shown a conventional table of ER values which correspond to the densities of the CO in exhaust gas.
  • the table is stored in a storage device, such as a ROM, in the controller, such as a microcomputer, of a combustion apparatus.
  • the ER values in Fig. 9 multiplied by 250 are employed because of the program provided for the microcomputer.
  • the density of the CO in the air depends not only on the density of the CO generated as exhaust gas, but also on the volume of all the exhaust gas. For example, even when densities of the CO in the exhaust gas is the same during a maximum combustion operation and during a minimum combustion operation, so long as the volumes of the exhaust gas differ, the volume of the CO discharged into the air, i.e., the density of the CO in the air in a substantially constant space, such as the inside of a room, also differs.
  • the density of the CO in the air is also affected by space, such as the open space inside a room which is adjacent to a flue and to which exhaust gas may leak from the flue.
  • space such as the open space inside a room which is adjacent to a flue and to which exhaust gas may leak from the flue.
  • the time which elapse before the safety operation is actuated differs from the time which elapse before the CO density of hemoglobin reaches a predetermined density (e.g., 25%). Since during combustion at the minimum capability both the volume of the exhaust gas and the volume of the CO discharged are comparatively small, the TR value reaches 1 before the CO density in hemoglobin reaches the predetermined density. Similarly, when the CO gas is discharged into a space which is larger than a predetermined reference space, the TR value reaches 1 before the CO density of hemoglobin reaches the predetermined density.
  • a predetermined density e.g. 25%
  • the safety operation may be activated to stop the combustion. Therefore, to more precisely monitor the CO density using the ER values, it is preferable that the ER values be employed while taking into account the volume of the exhaust gas and the volume of the space into which the CO gas is discharged.
  • a combustion apparatus comprising: a sensor for detecting a carbon monoxide density in exhaust gas; and a controller for determining a timing for performing a safe operation against carbon monoxide poisoning based on the carbon monoxide density detected by said sensor, and a combustion capability of the combustion apparatus or a volume of the exhaust gas.
  • the combustion apparatus when the combustion apparatus is activated, the density of the CO in the exhaust gas is detected by the CO sensor. Then, the combustion capability of the combustion apparatus, or the volume of the flue is detected. When the combustion operating time reaches the danger time corresponding to the CO density, detected by the CO sensor, and the combustion capability, or when the combustion operating time reaches the danger time corresponding to the CO density, detected by the CO sensor, and the volume of the flue a CO safety operation, such as the stopping of combustion, is performed.
  • the danger time that it is estimated CO poisoning causes a danger to a person in a room into which exhaust gas is leaking, is provided while taking into account not only the CO density but also the combustion capability of the device and the volume of the exhaust gas. Therefore, compared with when a continuous combustion enabled time is set merely by using the CO density, a precise time that CO poisoning constitutes a danger can be established while taking into account the operating condition of the combustion apparatus, such as its combustion capability. As a result, an accurate CO safety operation can be performed.
  • a combustion apparatus comprising: a sensor for detecting a carbon monoxide density in exhaust gas; and a controller for determining a timing for performing a safety operation against carbon monoxide based on the carbon monoxide density detected by said sensor and a volume of a room to which the exhaust gas is discharged.
  • an estimated value for the indoor CO density is obtained based on the density of the CO in the exhaust gas, which is detected by the CO sensor, and information concerning the volume of the room into which it is assumed exhaust gas is leaking.
  • a safety operation for CO gas is performed, so that an accurate CO safety operation can be conducted.
  • a combustion apparatus comprising: a sensor for detecting a carbon monoxide density in exhaust gas; and a controller for determining a timing for performing a safety operation against carbon monoxide based on the carbon monoxide density detected by said and a type of fuel gas.
  • the density of the CO in exhaust gas is detected by the CO sensor. And when the combustion run time reaches the danger time corresponding to the CO density, detected by the CO sensor, and the type of gas which is being used, a CO safety operation, such as the stopping of combustion, is performed.
  • the danger time that it is estimated CO poisoning will cause a danger to a person in a room is obtained by taking into account not only the CO density but also the type of gas which is being used. Therefore, compared with when the danger time is set using only the CO density, the time that the danger of CO poisoning will be reached can be precisely estimated, and accordingly, an accurate CO safety operation can be performed.
  • a combustion apparatus comprising: a sensor for detecting a carbon monoxide density in exhaust gas; and a controller for determining a timing for performing a safety operation against carbon monoxide poisoning based on the carbon monoxide density detected by said sensor and a ventilation pipe structure type of the combustion apparatus.
  • a danger time is set that a CO safety operation is to be performed which corresponds to the structure of the ventilation pipe attached to the outlet of the combustion apparatus, i.e., either a double pipe structure or a dual pipe structure.
  • a CO safety operation such as the stopping of combustion, is performed.
  • a CO safety operation can be performed which is appropriate for the ventilation pipe structure provided for the combustion apparatus, and the reliability of the CO safety operation can be improved.
  • a combustion apparatus comprising: means for obtaining an ER value which is a ratio t/T, in which the T is time when the carbon monoxide density in hemoglobin in blood reaches a predetermined density to be carbon monoxide poisoning, when a human being is exposed to an atmosphere in the carbon monoxide density detected each predetermined time unit t; and means for detecting an abnormality at the combustion apparatus when the sum TR of the ER values reaches a predetermined value, wherein the ER values are set in accordance with a the carbon monoxide density in exhaust gas, and a volume of the exhaust gas and/or a volume of a space into which the exhaust gas is discharged.
  • the ER value is determined while taking into account not only the density of the CO in the exhaust gas, but also the volume of the exhaust gas and/or the space into which the exhaust gas is discharged.
  • a combustion apparatus is provided which can acquire the precise ER value which matches the actual combustion operation, and which can perform a more correct CO safety operation.
  • a combustion apparatus is not limited to the apparatus shown in Fig. 1 which serves only as a uni-functional water heater, but may be a combination bath water heater, or an indoor combustion apparatus, such as a space heating appliance, an air conditioning appliance or an air conditioner.
  • Exhaust gas generated by the combustion apparatus is discharged exteriorly (outside a building), passing through a chimney (duct) 10 shown in Fig. 2.
  • duct chimney
  • FIG. 10 is a functional block diagram illustrating the controller of a combustion apparatus according to a first mode of the first embodiment which performs a CO safety operation.
  • the controller includes a data memory 112, a combustion time measurement unit 113, and a CO safety operation unit 114.
  • a combination bath water heater shown in Fig. 11 includes a burner 4a on the water heater side, which heats a heat exchanger 5 for the supply of hot water, and a burner 4b on the bath side, which heats a heat exchanger 15 for the supplementary heating of water.
  • Air for ventilation is supplied to the burners 4a and 4b by a fan 2.
  • a circulating pump 18 is driven to circulate hot water drawn from the bathtub, the circulating hot water being heated, as it passes through the heat exchanger 15, by the combustion at the burner 4b, so that the supplementary heating of water is performed. Since the operation of the heat exchanger 5 for the supply of hot water is the same as that for the water heater in Fig. 1, the same reference numerals are used to denote corresponding components.
  • Fig. 10 data shown in Fig. 12 are stored in the data memory 112.
  • the horizontal axis in Fig. 12 represents the density of the CO in exhaust gas, while the vertical axis represents the danger time that the indoor CO density by leaking of exhaust gas reaches a danger determination reference value, 300 ppm, for determining a CO poisoning danger level.
  • curve A represents the run state of the combustion apparatus when the combustion capability is 40000 Kcal/h
  • curve B represents the run state when the combustion capability is 29500 Kcal/h
  • curve C represents the run state when the combustion capability is 19500 Kcal/h.
  • Curve D represents the combustion state of burner 4b of the combination bath water heater shown in Fig. 11 when the combustion capability is 10000 Kcal/h.
  • the danger determination reference value of the indoor CO density is set at 300 ppm, and the danger time that the indoor CO density reaches the danger determination reference value after the exhaust gas having each CO density leaks indoor is stored in the data memory 112 for each combustion capability.
  • the data describing the relationship between the density of CO in exhaust gas and the danger time can be provided not only as they are in the graph, but also as table data or expression data.
  • the CO safety operation unit 114 obtains information concerning the exhaust gas CO density from the CO sensor 11, and also obtains information concerning the combustion capability from a combustion controller in the control unit 6.
  • a solenoid valve 21 for opening and closing the gas pipe 20 and a proportioning valve 22, the opening of which is controlled by a combustion controller 23, for regulating the volume of the gas which is supplied.
  • the combustion capability is so calculated that the temperature at the outlet of the heat exchanger 5 reaches a temperature set by a remote controller 7, and the combustion controller 23 controls a valve opening current which it supplies to the proportioning valve 22 so that the combustion capability is obtained.
  • the magnitude of the valve opening current which is supplied by the combustion controller 23 to the proportioning valve 22 corresponds to the opening of the proportioning valve 22, i.e., the volume of the gas which is to be supplied, and matches the combustion capability obtained by the combustion controller 23.
  • data for the detected valve opening current is employed as combustion capability information.
  • danger time T that the indoor CO density reaches a danger determination reference value is obtained from the data stored in the data memory 112 in Fig. 12. Then, the elapsed combustion time following the start of the combustion is monitored by the combustion time measuring unit 113. When the combustion time reaches the danger time T, it is assumed that the indoor CO density value has reached the danger determination reference value, and a safety operation, such as the stopping of the combustion, is performed.
  • danger times T corresponding to the exhaust gas CO density are provided for each combustion capability, so that an adequate danger time T can be obtained which corresponds to the information concerning the combustion capability and the information concerning the exhaust gas CO density detected by the CO sensor 11.
  • the accuracy of the CO safety operation can be considerably improved, and an erroneous operation, such as the stopping of combustion even though the indoor CO density has not yet reached the danger level, can be prevented.
  • the data for the valve opening current supplied to the proportioning valve 22 is employed as the combustion capability information.
  • the same effect can be obtained when data for the volume of the gas supplied or data for the combustion capability calculated by the combustion controller 23 are used. If the data for the volume of the gas supplied are to be used as data for the combustion capability, a gas flow rate sensor is provided along the gas pipe 20 and a detection signal for the volume of the gas supplied is transmitted by the sensor to the CO safety operation unit 114.
  • the second mode is the same as the first mode of the first embodiment, except that instead of the combustion capability, data for the air flow rate of a fan, which corresponds to the exhaust volume, is used to perform the CO safety operation. Since the combustion operation is performed at the air flow rate of the fan which matches the combustion capability, a correlation is established between the combustion capability and the exhaust volume, i.e., the air flow rate of the fan, and in the second mode of the first embodiment the data for the air flow rate of the fan is employed instead of the data for the combustion capability. Therefore, as is shown in Fig. 14, the relationship between the exhaust gas CO density and the danger time T for each air flow rate of the fan is stored in the data memory 112 in Fig. 10.
  • Curve E in Fig. 14 represents data for the operating state of the fan 2 when the rotation speed (revolutions) is 6000 rpm; curve F represents data for the operating state of the fan 2 when the rotation speed (revolutions) is 5500 rpm; and curve G represents data for the operating state of the fan 2 when the rotation speed (revolutions) is 5000 rpm.
  • the data which describe the relationship existing between the exhaust gas CO density and the danger time T are provided for each air flow rate, and these data are stored in the data memory 112 where they are recorded using an adequate form, such as graph data, as table data or as expression data.
  • the CO operation unit 114 fetches air flow rate information, as is indicated by the broken line in Fig. 10. As is shown in Figs. 1 and 11, a fan rotation sensor 24, such as a Hall IC, is provided to detect the revolutions of the fan 2, and transmits detected fan rotation information as air flow rate data to the CO safety operation unit 114.
  • a fan rotation sensor 24 such as a Hall IC
  • the CO safety operation unit 114 receives the exhaust gas CO density from the CO sensor 11, and the air flow rate information from the fan rotation sensor 24.
  • the data shown in Fig. 14, which are stored in the data memory 112, are employed to obtain the danger time T which corresponds to the air flow rate and the exhaust gas CO density.
  • a CO safety operation such as the stopping of combustion, is performed.
  • the CO safety operation is performed by obtaining information for the air flow rate, which corresponds to the information provided by the CO sensor 11, and the exhaust volume. Therefore, as well as in the first mode of this embodiment, an accurate CO safety operation can be performed in accordance with an adequate danger time T which corresponds to the operating state of the combustion apparatus, so that the same effect can be obtained as in the first mode.
  • the fan revolutions are employed as data for the air flow rate.
  • an air flow rate sensor or an air speed sensor may be provided along the ventilation pipe leading from the air intake side to the flue side in order to detect the air flow rate directly or indirectly, and the detected data may be used as air flow rate data.
  • a fan drive current may also be used as air flow rate data.
  • Fig. 15 is a block diagram illustrating the arrangement for a third mode according to the first embodiment of the present invention.
  • the controller in this mode includes an exhaust gas CO density sampling unit 125, a tsp/T calculation unit 127, a timer mechanism 126, a data memory 112 and a CO safety operation unit 114.
  • the CO density sampling unit 125 employs a predetermined sampling time unit tsp to perform the sampling of the exhaust gas CO density Cext which is detected by the CO sensor 11 following the start of combustion. Specifically, the sampling time is set to 10 seconds, for example. Each second the CO density sampling unit 125 obtains the information detected by the CO sensor 11, and calculates the average and establishes it as the exhaust gas CO density for each sampling time unit. It should be noted that the sampling is performed in accordance with a signal issued by the timer mechanism 126, which is constituted by a timer or a clock.
  • the tsp/T calculation unit 127 obtains the density of the CO in the exhaust gas, which is detected by using the sampling time unit tsp input by the CO density sampling unit 125, and calculates the tsp/T.
  • the graph data for a curve to be used are selected based on the combustion capability information which is fetched in the same manner as in the first mode of the first embodiment.
  • the combustion capability information indicates, for example, 29500 kcal/h
  • data for curve B is selected and the danger time T is calculated in accordance with this data.
  • danger time T is the time that the indoor CO density value reaches the danger determination reference value Cth of 300 ppm, for example, when an exhaust CO density of Cext, which is detected by the CO sensor 11, is leaked indoors.
  • the sampling time tsp is divided by the danger time T until the reference value is obtained, so that the ratio of the sampling time tsp to the time T can be obtained.
  • the value represented by tsp/T means that a period of time has elapsed at a ratio of tsp/T of the safety time T and only a period of time at a ratio of (1 - tsp/T) remains.
  • time tsp of time T elapses before the indoor CO density value reaches the danger determination reference value, and the remaining safety time is a period of only T - tsp.
  • the tsp/T calculation unit 127 calculates tsp/T, and at the next sampling time it calculates tsp/T in accordance with the data for the exhaust gas CO density. The most currently obtained value is added to the tsp/T obtained at the preceding sampling time. At each sampling time, the tsp/T calculation unit 127 sequentially adds the product of tsp times the tsp/T values obtained at the individual sampling times.
  • tsp/T1 when at the first sampling tsp/T1 is obtained using T1, which is for the exhaust CO density Cext1, at the next sampling time tsp/T2 is calculated by using T2, which is for the exhaust CO density Cext2, and the value provided by tsp/T1 + tsp/T2 is acquired as their sum. Further, at the third sampling time, tsp/T3 is calculated by using T3, which is for the exhaust CO density Cext3, and the value provided by tsp(1/T1 + 1/T2 +1/T3) is acquired as their sum. As is described above, the tsp/T calculation unit 127 adds the tsp/T values obtained at the individual sampling times, and transmits the sum to the CO safety operation unit 114.
  • the CO safety operation unit 114 monitors the sum received from the tsp/T calculation unit 127. When the sum reaches a value which is set in advance, for example, 1.0, it is assumed that the indoor CO density Croom has reached the danger determination reference value Cth, which is set in advance, and a CO safety operation, such as the stopping of the supply of gas to the burner 4, is performed.
  • the third mode of the first embodiment data are selected for the relationship between the exhaust CO density, which corresponds to the combustion capability of the combustion apparatus in the operating state, and the danger time T. Then, based on the data concerning the combustion capability, tsp/T is calculated for each of the sampling times and results are added together in accordance with the exhaust gas CO density detected by the CO sensor 1. Therefore, the danger time that the indoor CO density value reaches the danger determination reference value can be precisely established, while taking into account the combustion capability during combustion. As a result, the accuracy of the CO safety operation can be even more improved.
  • the exhaust CO density detected by the CO sensor 11 is sampled by the CO density sampling unit 125, and the resultant value is added by the tsp/T calculation unit 127.
  • the tsp/T calculation unit 127 selects, from among various data stored in Fig. 14, data which correspond to the input air flow rate information. When, for example, the air flow rate of the fan is 6000 rpm, the data for curve E are selected, and danger time T, which corresponds to the exhaust CO density, is obtained. Then, in the same manner as in the third mode, the tsp/T values are calculated at the sampling times and are added together. When the sum of the tsp/T values reaches 1, the CO safety operation is performed by the CO safety operation unit 114.
  • the combustion capability correlates with the air flow rate of the fan, and the CO safety operation is performed using information either for the combustion capability or for the air flow rate.
  • the dependability of the CO safety operation can be considerably improved. That is, if the combustion capability and the air flow rate differ while the CO density of the exhaust gas is the same, the exhaust value per time unit differs. When the exhaust gas leak indoors, the degree of indoor contamination due to the CO gas differs depending on the combustion capability and the air flow rate. Since the combustion capability and the air flow rate are disregarded in the conventional method for performing the CO safety operation, the dependability of the CO safety operation can not be enhanced. However, in the above modes since the CO safety operation is performed while taking the combustion capability or the air flow rate into account, the dependability of the CO safety operation can be enhanced, and the accuracy of the CO safety operation can also be increased.
  • the present invention is not limited to the above modes in the embodiment, and various modes can be employed.
  • the burner 4 (4a or 4b) having a single combustion stage is employed, as is shown in Fig. 16 a burner 4 having multiple combustion stages may be employed.
  • the combustion face is divided into multiple stages (two stages in Fig. 16), solenoid valves 21a and 21b are switched to perform combustion at face A, or at both faces A and B at the same time, in accordance with a combustion capability which is requested.
  • the CO safety operation method using air flow rate information provides particularly preferable results.
  • the indoor CO density is used to specify the reference value for determining whether an person in a troom has entered the critical condition caused by CO poisoning.
  • the reference value may be specified by using the volume of CO absorbed by hemoglobin, i.e., by the hemoglobin CO density.
  • the critical condition by CO poisoning is entered when the hemoglobin CO density value reaches the danger determination reference value (e.g., 10%), and the time that the hemoglobin CO density value reaches the reference value is defined as danger time T.
  • Correlation data for the danger time T and the exhaust CO density must be prepared and stored in the data memory 112 for each combustion capability or exhaust volume, i.e., a air flow rate.
  • the correlation data shown in Fig. 12 for the exhaust CO density and danger time T are provided for each combustion capability.
  • the correlation data may be provided only for a typical combustion capability.
  • the danger time T which is obtained using the correlation data for the specific combustion capability is multiplied by a correction coefficient which is set in advance, so that a danger time T for another combustion capability can be obtained.
  • the correction coefficient can be provided as a value which corresponds to a difference, or to a ratio of a difference of exhaust volumes for the time unit relative to a difference between the specific combustion capability and the actual combustion capability in the operating state (combustion capability information).
  • the correlation data shown for the exhaust CO density and the danger time T may be provided for one specific air flow rate.
  • the danger time T which is obtained using the correlation data for the specific air flow rate is multiplied by a correction coefficient which is set in advance, so that a danger time T for another air flow rate relative to the exhaust CO density can be obtained.
  • the correction coefficient can be provided as a value which corresponds to a difference, or to a ratio of a difference of exhaust volumes for the time unit relative to a difference between the specific air flow rate and the actual air flow rate in the operating state (air flow rate information).
  • FIG. 17 is a functional block diagram showing the controller for a combustion apparatus which performs a CO safety operation according to a first mode of the second embodiment of the present invention.
  • the controller includes an indoor CO density estimate calculation unit 212, a combustion time measurement unit 213, and a CO safety operation unit 214.
  • the indoor CO density estimate calculation unit 212 makes an indoor CO density estimate when it is presumed that the total volume of the exhaust gas is leaking indoors, by using an equation, which is provided in advance, which includes as parameters the combustion time of the combustion apparatus and the indoor space volume.
  • Croom denotes an indoor CO density (ppm);
  • Q3 denotes a total exhaust gas volume (m 3 /h);
  • X denotes a ratio of the volume of exhaust gas which leaks indoors to the total exhaust gas;
  • Cext denotes the CO density (ppm) in the exhaust gas;
  • n denotes a ventilation rate using a ventilation fan;
  • V denotes the volume of a room (m 3 ); and
  • t denotes a combustion time.
  • Fig. 18 is a diagram showing an indoor model concerning the calculation of equation (1).
  • an air intake pipe 215 is used to introduce external air into the combustion apparatus, and in a flue 210 there is a defective portion 216. Exhaust gas from the combustion apparatus leak into a room at the defective portion 216.
  • Equation (1) parameters Q3, X, n and V are provided as data which are already known.
  • Cext is detected as the exhaust gas CO density by the CO sensor 11.
  • the combustion time t is measured as a known value by a combustion time measurement unit 213, such as a timer or a clock.
  • a danger determination reference value Cth of 300 ppm for the indoor CO density is provided in advance for the CO safety operation unit 214.
  • the CO safety operation unit 214 compares the reference value Cth with the value Croom obtained by the indoor CO density estimate calculation unit 212. When the indoor CO density value Croom reaches the reference value, a CO safety operation, such as the stopping of fuel to the burner (the closing of a valve located along the gas pipe which communicates with the burner), is performed.
  • a plurality of the reference values may be set, and a plurality of CO safety operations can be performed in accordance with the indoor density value. For example, when at the first step the indoor CO density value Croom, which is obtained by the indoor CO density estimate calculation unit 212, reaches a first reference value, the fan 2 is rotated faster and the volume of air is increased to improve the combustion at the burner 4; and when, in spite of this, the estimated indoor CO density value Croom reaches a second reference value at the second step, the supply of fuel is stopped.
  • the controller for this mode in Fig. 19 comprises exhaust gas CO density sampling unit 217, a tsp/T calculation unit 218, a timer mechanism 220, a data memory 221, and a CO safety operation unit 214.
  • the exhaust gas CO density sampling unit 217 employs a predetermined sampling time unit tsp, which is provided in advance, to perform the sampling for the exhaust gas CO density value Cext which is detected by the CO sensor 11 following the starting of the combustion.
  • the CO density sampling unit 217 sets the sampling time to 10 seconds, for example, obtains the detection information from the CO sensor 11 for each second, and calculates the average as the exhaust gas CO density for each sampling time unit.
  • the sampling is performed based on a signal issued by the timer mechanism 220, which is constituted by a timer or a clock.
  • Time T along the vertical axis in the graph represents the time exhaust gas having the CO density Cext must leak indoors before the indoor CO density value Croom reaches the danger determination reference value Cth, which is provided in advance.
  • the danger determination reference value Cth e.g. 300 ppm
  • the indoor CO density value Croom reaches the danger determination reference value Cth when time T2 has elapsed.
  • the group data in Fig. 20 are obtained by calculation or through experiment.
  • expression (1) is employed.
  • time T which must elapse before the indoor CO density value Croom reaches the danger determination reference value Cth, is obtained, and a graph is prepared using the obtained time T so that the data shown in Fig. 20 can be acquired.
  • a CO sensor which is separately provided in a room measures time T1 that the CO sensor detects danger determination reference value Cth after exhaust gas having a constant CO density Cext1 has leaked inside.
  • the data shown in Fig. 20 are obtained and are stored in the data memory 221.
  • the tsp/T calculation unit 218 obtains the CO density of exhaust gas, which was detected each sampling time unit tsp input by the exhaust gas CO density sampling unit 217, and calculates a value tsp/T.
  • Time T is obtained using data, shown in Fig. 20, which are stored in the data memory 221, and indicates a period which is required before the indoor CO density value reaches the danger determination reference value Cth, when it is assumed that the exhaust gas having the CO density Cext, which is detected by the CO sensor 211, has leaked into a room.
  • the ratio of sampling time tsp to time T is obtained by dividing sampling time tsp by time T.
  • the ratio tsp/T is used to indicate that safety time T of time tsp/T has elapsed and only safety ratio (1 - tsp/T) remains. In other words, of time T, that the indoor CO density value reaches the danger determination reference value, tsp has elapsed, and for safety only time T - tsp remains.
  • the tsp/T calculation unit 218 calculates tsp/T, and at the second sampling time, it also calculates tsp/T using the data for the detected exhaust gas CO density. The tsp/T calculation unit 218 then adds the current tsp/T to the tsp/T which was obtained the preceding sampling time. In this manner, the tsp/T calculation unit 218 sequentially adds the tsp/T values each time they are obtained at the individual sampling times. When tsp/T1 is obtained at the first sampling time and tsp/T2 is obtained at the second sampling time, the sum for tsp/T1 + tsp/T2 is calculated.
  • the tsp/T calculation unit 218 adds together the tsp/T values which are obtained at the individual sampling times, and then it transmits the results to the CO safety operation unit 214.
  • the CO safety operation unit 214 monitors the results received from the tsp/T calculation unit 217. When the results equal a value which is set in advance, e.g., 1.0, it is assumed that the indoor CO density value Croom reaches the danger determination reference value Cth which was set in advance, and a CO safety operation, such as the stopping of the supply of gas to the burner 4, is performed.
  • a CO safety operation such as the stopping of the supply of gas to the burner 4
  • the indoor CO density is calculated by using the equation while taking the indoor area volume into account.
  • Equation (1) in a simple form can be provided to transform the exhaust gas CO density into the indoor CO density while taking the indoor area volume into account. Therefore, for that calculation, instead of a large computer, only a microcomputer mounted on the control unit 6 of the combustion apparatus is satisfactory, and a more detailed safety operation can be performed for CO gas. In addition, since the actual indoor CO density can be employed for the CO safety operation, the accuracy and the reliability of the CO safety operation are increased.
  • the present invention is not limited to this embodiment, and can be variously modified.
  • the form of the graph data shown in Fig. 20 is employed for data which are used to calculate, by employing the exhaust gas CO density, the time T which is required for the indoor CO density value to equal the danger determination reference value.
  • data can be provided in a desired form, such as table data or as equation data.
  • Fig. 21 is a functional block diagram illustrating the arrangement of controller for a combustion apparatus which performs a CO safety operation according to a first mode of the third embodiment.
  • the controller includes a data memory 312, a gas type setting unit 309, a combustion time measurement unit 313, and a CO safety operation unit 314.
  • the gas type setting unit 309 sets the type of gas to be used.
  • a plurality of switches may be provided to select the type of gas to be used.
  • a gas type select switch provided for an ordinary water heater is used as the gas type setting unit.
  • a gas type to be employed can be designated, such as 13A, 12A, L1 (6B, 6C, 7A), L2 (5A, 5B, 5AN), L3 (4A, 4B, 4C), 6A, 5C or LPG.
  • Fig. 22 In the data memory 312, data shown in Fig. 22 concerning the correlation existing between the exhaust CO density and danger time T are stored for each gas type.
  • the horizontal axis of the graph data in Fig. 22 represents the exhaust gas CO density, and the vertical axis represents the danger time T that, after exhaust gas has leaked indoors, the indoor CO density reaches a danger determination reference value of 300 ppm, which is used to determine a critical condition by CO poisoning.
  • Curve A in the graph indicates L1 gas
  • curve B indicates 13A gas
  • curve C indicates propane gas.
  • the danger determination reference value for the indoor CO density is set to 300 ppm, and the danger time which is required before the indoor CO density value reaches the reference value, when it is assumed that exhaust gas having each CO density has leaked indoors, is stored in the data memory for each gas type.
  • the data describing the relationship of the exhaust CO density and the danger time can be provided as table data or equation data.
  • the CO safety operation unit 314 receives from the CO sensor 11 information concerning the exhaust gas CO density, and also receives information concerning the gas type employed from the gas type setting unit 309.
  • the CO safety operation unit 314 employs the data in Fig. 22, which is stored in the data memory 312, to acquire the danger time T which is required before the indoor CO density value reaches the danger determination reference value after exhaust gas has leaked indoors.
  • the CO safety operation unit 314 monitors the combustion time which is measured by the combustion time measurement unit 313 from the start of the combustion. When the elapsed combustion time reaches the danger time T, it is assumed that the indoor CO density value reaches the danger determination reference value, and a safety operation, such as the stopping of combustion, is performed.
  • a danger time T for a corresponding exhaust CO density is provided for each gas type, and the gas type information and the information concerning the exhaust CO density detected by the CO sensor 11 are employed to calculate a danger time T, so that the CO safety operation can be performed in accordance with the time T. Therefore, an adequate danger time T can be obtained in accordance with an individual exhaust CO density and the gas type, and the accuracy of the CO safety operation can be drastically increased. As a result, such an erroneous operation as the stopping of the combustion, even though the indoor CO density has not reached the dangerous level, can be performed.
  • Fig. 23 is a functional block diagram illustrating controller for a combustion apparatus which performs a CO safety operation according to a second mode of the third embodiment of the present invention.
  • the controller comprises an exhaust CO density sampling unit 325, a tsp/T calculation unit 327, a timer mechanism 326, a data memory 312, and a CO safety operation unit 314.
  • the CO density sampling unit 325 employs a predetermined sampling time unit tsp, which is provided in advance, to perform the sampling of the CO density Cext in exhaust gas which is detected by a CO sensor following the starting of the combustion. Specifically, the CO density sampling unit 325 sets the sampling time to, for example, 10 seconds, obtains detection information from the CO sensor each second, and calculates for each sampling time unit the average value as the exhaust gas CO density. The sampling process is performed in accordance with a signal issued by the timer mechanism 326, which is constituted by a timer or a clock.
  • the tsp/t calculation unit 327 obtains the CO density of exhaust gas, which was detected for each sampling time unit tsp received by the exhaust gas CO density sampling unit 325, and calculates a value tsp/T.
  • graph data for a curve to be used are selected based on the gas type information which is received from the gas type setting unit 309.
  • the gas type is 13A
  • the data for curve B are selected, and the danger time T is calculated based on the data.
  • the danger time T indicates a period which must elapse before the indoor CO density value reaches the danger determination reference value Cth of 300 ppm, for example, while it is assumed that exhaust gas having the CO density Cext, which is detected by the CO sensor 211, is leaking.
  • the ratio of sampling time tsp to time T is obtained by dividing sampling time tsp by time T.
  • the ratio tsp/T is used to indicate that of safety time T time tsp/T has elapsed, and only safety ratio (1 - tsp/T) remains. In other words, of time T, that the indoor CO density value reaches the danger determination reference value, tsp has elapsed, and for safety only time T - tsp remains.
  • the tsp/T calculation unit 327 calculates tsp/T, and at the second sampling time it also calculates tsp/T using the data for the detected exhaust gas CO density. The tsp/T calculation unit 327 then adds the current tsp/T to the tsp/T which was obtained the preceding sampling time. In this manner, the tsp/T calculation unit 327 sequentially adds the tsp/T values each time they are obtained at the individual sampling times. When tsp/T1 is obtained at the first sampling time and tsp/T2 is obtained at the second sampling time, the sum for tsp/T1 + tsp/T2 is calculated.
  • the tsp/T calculation unit 327 adds together the tsp/T values which are obtained at the individual sampling times, and then it transmits the results to the CO safety operation unit 314.
  • the CO safety operation unit 314 monitors the results received from the tsp/T calculation unit 327. When the results equal a value which is set in advance, e.g., 1.0, it is assumed that the indoor CO density value Croom reaches the danger determination reference value Cth, which is set in advance, and a CO safety operation, such as the stopping of the supply of gas to the burner 4, is performed.
  • a CO safety operation such as the stopping of the supply of gas to the burner 4
  • data for the relationship between the exhaust CO density and the danger time T are selected in accordance with the type of gas used for the combustion apparatus in the operating state. Based on the data corresponding to the gas type, the value of tsp/T is calculated each sampling time in accordance with the exhaust gas CO density which is detected by the CO sensor 11, and the obtained tsp/T values are sequentially added together.
  • the danger time which must elapse before the indoor CO density value reaches the danger determination reference value can be precisely determined, and the accuracy of the CO safety operation can be considerably increased.
  • the present invention is not limited to these modes, and can be variously modified.
  • the reference value that a person in a room enters the critical condition caused by CO poisoning is specified using the indoor CO density.
  • the quantity of CO absorbed by the hemoglobin in his or her blood i.e., the hemoglobin CO density
  • the reference value e.g. 10%
  • the time that the hemoglobin CO density value reaches the reference value is defined as danger time T.
  • Correlation data for the danger time T and a corresponding exhaust CO density must be prepared for each gas type and stored in the data memory 312.
  • correlation data like the data shown in Fig. 3, are provided for the exhaust CO density and the danger time T in order to take into account the combustion capability.
  • the correlation data may be provided for only one specific gas type.
  • the danger times T for the other gas types can be obtained when the danger time T, which is acquired by using the correlation data for the specific gas type, is multiplied by a compensation coefficient which is provided in advance.
  • the compensation coefficient can be a difference or a ratio of exhaust volumes per time unit between a specific gas type and the gas type which is actually employed.
  • the specific gas type may be a gas type group which is arbitrarily determined while taking into consideration the values of the exhaust gas elements which are detected.
  • Fig. 24 is a functional block diagram illustrating controller for a combustion apparatus which performs a CO safety operation according to a first mode of the fourth embodiment.
  • the controller in this mode includes a data memory 417, combustion time measurement unit 418, a CO safety operation unit 420, and a ventilation structure selection unit 421.
  • the ventilation structure selection unit 421 is used to set the ventilation structure mounted on the exhaust side of a water heater.
  • the ventilation structure selection unit 421 is provided as a switch, for example, on the control board of a control unit 412. When the switch is moved to one side, the double ventilation pipe structure shown in Fig. 5 is selected, and when the switch is moved to the other side, the dual ventilation pipe structure shown in Fig. 6 is selected. In other words, the double ventilation pipe structure and the dual ventilation pipe structure are selected by the manipulation of the switch.
  • the information concerning the ventilation structure selected by the ventilation structure selection unit 421 is transmitted to the CO safety operation unit 420.
  • condition data shown in Fig. 25 for starting the CO safety operation which corresponds to the double pipe system and the condition data shown in Fig. 26 for starting the CO safety operation which corresponds to the dual pipe structure.
  • the horizontal axis for the graph data in Fig. 25 represents the exhaust gas CO density, and the vertical axis represents the danger time which must elapse before exhaust gas leaking into a room attain an indoor CO density which reaches a reference value of 300 ppm which is used to determine the danger level for CO poisoning.
  • Curve A in the graph represents the operating state when the combustion capability of the combustion apparatus is 40000 Kcal/h; curve B represents the operating state when the combustion capability is 29500 Kcal/h; and curve C represents the operating state when the combustion capability is 19500 Kcal/h.
  • the reference value for the determination of the danger level of the indoor CO density is set to 300 ppm.
  • the danger time which must elapse before the indoor CO density reaches the reference value when exhaust gas having a specific CO density leaks into a room, is stored in the data memory 417 as condition data for starting the CO safety operation for the double pipe system.
  • the data describing the relationship existing between the exhaust CO density and the danger time can be provided not only as graph data, but also as table data or equation data.
  • the horizontal axis for the graph data in Fig. 26, as well as in Fig. 25, represents the exhaust gas CO density
  • the vertical axis represents the danger time which must elapse after gas begins leaking into a room before the indoor CO density value reaches a reference value of 300 ppm, which is used for the determination of the critical condition by CO poisoning.
  • Curve E in the graph represents the data for the operating state when the rotational speed (revolutions) of a fan 405 is 6000 rpm
  • curve F represents the data for the operating state when the rotational speed (revolutions) is 5500 rpm
  • curve G represents the data for the operating state when the rotational speed (revolutions) is 5000 rpm.
  • condition data describing the relationship existing between the exhaust CO density and the danger time T are provided for each air flow rate of the fan.
  • condition data for starting the CO safety operation for the dual pipe structure are stored in the data memory 417 where they are recorded using an adequate form, such as graph data, table data or equation data.
  • the CO safety operation 420 obtains information for the exhaust gas CO density, which is detected by a CO sensor 416, and also corresponding combustion capability and air flow rate information and exhaust volume information.
  • the combustion capability information is received from the combustion controller in the control unit 412.
  • a solenoid valve 414 located along a gas pipe 407 for a burner 406 are a solenoid valve 414, for opening and closing the gas pipe 407 and a proportioning valve 415, for controlling the volume of the gas to be supplied in accordance with the valve opening.
  • the opening of the proportioning valve 415 is controlled by a combustion control unit 423.
  • the combustion control unit 423 calculates a combustion capability that provides a temperature at the outlet of a heat exchanger 408 which is equal to a temperature set by a remote controller 413, and controls the magnitude of a valve opening current which it supplies to the proportioning valve 415, so that the above combustion capability can be achieved.
  • the magnitude of the valve opening current, which is supplied by the combustion controller 423 to the proportioning valve 415 corresponds to the opening of the proportioning valve 415, i.e., the volume of gas supplied, and further matches the combustion capability which is obtained through calculation by the combustion controller 423.
  • this mode data detected for the valve opening current are employed as the combustion capability information.
  • a fan revolution sensor 424 such as a Hall IC, is provided to detect the revolutions of the fan 405, and the fan revolution information detected by the fan revolution sensor 424 is used as the air flow rate information.
  • the CO safety operation unit 420 selects the data in Fig. 25 as the condition data for starting the CO safety operation. If the dual pipe structure is selected by the ventilation structure selection unit 421, the CO safety operation unit 420 selects the data in Fig. 26 as the condition data for starting the CO safety operation.
  • the danger time T which corresponds to the detected CO density is obtained from the curve which corresponds to the combustion capability.
  • the CO safety operation unit 420 permits the combustion time measurement unit 418 to monitor the time which elapses from the start of the combustion. When the combustion time reaches the danger time T, the CO safety operation unit 420 ascertains that the indoor CO density value reaches the danger determination reference value, and performs a safety operation, such as the stopping of the combustion.
  • the CO safety operation unit 420 obtains information for the density of the CO in the exhaust gas which is detected by the CO sensor 416, and the air flow rate information which is the exhaust gas volume information. Furthermore, from the graph data for a curve which represents the air flow rate information, the CO safety operation unit 420 acquires the danger time T which corresponds to the detected density of the CO in the exhaust gas. In addition, when danger time T is reached following the start of combustion, the CO safety operation unit 420 ascertains that the indoor CO density value has reached the danger determination reference value, and the unit 420 performs a safety operation, such as stopping of the combustion.
  • the condition data for starting the CO safety operation are selected in accordance with the actual ventilation structure of the water heater. Since the actual dedicated data for a ventilation structure are employed to perform the CO safety operation, a CO safety operation which corresponds to the actual ventilation structure can be precisely performed, so that the CO safety operation can be performed more correctly and more reliably.
  • the data for the valve opening current supplied to the proportioning valve 415 are employed as the combustion capability information.
  • the data for the volume of gas supplied or the numerical data for the combustion capability obtained by the combustion control unit 423 may be employed. It should be noted that when the data for the volume of gas supplied are employed as the combustion capability data, a gas flow rate sensor, etc., is provided along the gas supply pipe 407, and a gas volume detection signal is transmitted by the sensor to the CO safety operation unit 420.
  • fan rotation data are employed as the air flow rate data.
  • a flow rate sensor or an air speed sensor may be provided along a ventilation path which extends from the air intake side to the flue side in order to directly or indirectly detect the flow rate, and the detected data can be used as the air flow rate information.
  • Fig. 28 is a functional block diagram illustrating controller for a combustion apparatus which performs a CO safety operation according to a second mode of the fourth embodiment of the present invention.
  • the controller in this mode includes an exhaust CO density sampling unit 425, a tsp/T calculation unit 427, a timer mechanism 426, a data memory 417, a CO safety operation unit 420, and a ventilation structure selection unit 421.
  • the CO density sampling unit 425 employs a predetermined sampling time unit tsp, which is set in advance, to sample density Cext of the CO in exhaust gas which is received from the CO sensor 416 following the starting of the combustion. Specifically, the CO density sampling unit 425 sets the sampling time to 10 seconds, for example, obtains detection information from the CO sensor 416 each second, and calculates the average value to obtain the exhaust gas CO density for each sampling time unit.
  • the sampling process is performed in accordance with a signal issued by the timer mechanism 426, which is constituted by a timer or a clock.
  • condition data for starting the CO safety operation are respectively stored in the data memory 417 for the ventilation structures shown in Figs. 25 and 26.
  • the ventilation structure select switch 421 is used to select the double ventilation pipe structure or the dual pipe structure, as in the first mode.
  • the tsp/t calculation unit 427 obtains the density of the CO in exhaust gas, which was detected each sampling time unit tsp provided by the exhaust gas CO density sampling unit 425, and calculates a tsp/T value. Danger time T is calculated using the data in Fig. 25 or 26, which are stored in the data memory 417.
  • the ventilation setup information for the ventilation structure selection unit 421 are employed to determine which of the data in Figs. 25 and 26 are to be used. In other words, the data in Fig. 25 are selected for the double ventilation pipe structure, while the data in fig. 26 are selected for the dual ventilation pipe structure. When the data in Fig. 25 are selected, graph data for one of the curves in Fig.
  • the combustion capability information which is obtained in the same manner as in the first mode of the fourth embodiment.
  • the combustion capability is 29500 Kcal/h
  • the data for curve B are selected, and a danger time T is calculated based on the data.
  • graph data for one of curves in Fig. 26 are selected based on the air flow rate information which is obtained in the same manner as in the first mode of the fourth embodiment.
  • the air flow rate of the fan is 6000 rpm
  • the data for curve E are selected, and a danger time T corresponding to the exhaust CO density is calculated.
  • the danger time T is the time which must elapse before the indoor CO density value reaches the danger determination reference value Cth of 300 ppm, for example, while assuming that exhaust gas having the CO density Cext, which is detected by the CO sensor 416, are leaking into a room.
  • the sampling time tsp is divided by the thus obtained time T, so that the ratio of the sampling time tsp to the time T can be obtained.
  • the ratio tsp/T is used to indicate that of safety time T time tsp/T has elapsed- and only safety ratio (1 - tsp/T) remains. In other words, of time T that the indoor CO density reaches the danger determination reference value, tsp has elapsed and only time T - tsp remains for safety.
  • the tsp/T calculation unit 427 calculates tsp/T, and at the second sampling time it also calculates tsp/T using the data for the detected CO density of exhaust gas. The tsp/T calculation unit 427 then adds the current tsp/T to the tsp/T which was obtained at the preceding sampling time. In this manner, the tsp/T calculation unit 427 sequentially adds the values tsp/T when they are obtained at the individual sampling times. When tsp/T1 is obtained at the first sampling time and tsp/T2 is obtained at the second sampling time, the sum for tsp/T1 + tsp/T2 is calculated.
  • the tsp/T calculation unit 427 adds the tsp/T values which are obtained at the individual sampling times, and transmits the results to the CO safety operation unit 420. It should be noted that the sum of the tsp/T values is also calculated when the graph data in Fig. 26 are selected.
  • the CO safety operation unit 420 monitors the results received from the tsp/T calculation unit 427. When the results equal a value which is set in advance, e.g., 1.0, it is assumed that the indoor CO density value reaches the danger determination reference value Cth which is set in advance, and a CO safety operation, such as the stopping of the supply of gas to the burner 406, is performed.
  • a CO safety operation such as the stopping of the supply of gas to the burner 406, is performed.
  • the tsp/T values are calculated by using corresponding data for the air flow rate.
  • the Tsp/T values which are obtained at the individual sampling times by using the curve data corresponding to the air flow rate are added together at the sampling times. When the sum reaches 1, the CO safety operation is performed.
  • the tsp/T is sequentially calculated and added at each sampling time. Therefore, the danger time which must elapse before the indoor CO density value reaches the danger determination reference value can be precisely established, while taking into account the change in the combustion capability of the combustion operation and the change in the air flow rate of the fan. As a result, since the condition data for starting the CO safety operation are employed in accordance with the ventilation pipe structure, the accuracy of the CO safety operation can be further improved.
  • the present invention is not limited to these modes, and can be variously modified.
  • the reference value that a person in a room enters the critical condition caused by CO poisoning is specified using the indoor CO density.
  • the quantity of CO absorbed by the hemoglobin of his or her blood i.e., the hemoglobin CO density
  • the reference value e.g. 10%
  • the time that the hemoglobin CO density reaches the reference value is defined as danger time T.
  • correlation data for danger time T and a corresponding exhaust CO density must be prepared for each exhaust volume, i.e., the air flow rate, and must be stored in the data memory 417.
  • correlation data for the exhaust CO density and danger time T like the data shown in Fig. 25, are provided for each combustion capability.
  • the correlation data may be provided for only one specific combustion capability.
  • danger time T for the other combustion capabilities can be obtained when danger time T, which is acquired by using the correlation data for the specific combustion capability, is multiplied by a compensation coefficient which is provided in advance.
  • the compensation coefficient can be a difference or a ratio of exhaust volumes per time unit, which corresponds to a difference between the specific combustion capability and the combustion capability which is actually employed for the operation (input combustion capability information).
  • correlation data for the exhaust CO density and danger time T may be provided for one specific air flow rate of the fan.
  • danger time T for the other air flow rates can be obtained when danger time T, which is acquired by using the correlation data for the specific air flow rate, is multiplied by a compensation coefficient which is provided in advance.
  • the compensation coefficient can also be a difference or a ratio of exhaust volumes per time unit which corresponds to a difference between the specific air flow rate and the air flow rate which is actually employed for the operation (input air flow rate information).
  • condition data for starting the CO safety operation may be provided for each fuel gas type in order to calculate danger time T by using the exhaust CO density and the combustion capability (or the air flow rate). Since gas elements differ, depending on the gas type, the exhaust volume generated by the time unit also differs in accordance with the gas type. Therefore, even when exhaust gas having the same CO density are leaked into a room, the indoor CO contamination is increased for the gas type which has a greater time unit exhaust volume. Therefore, when the condition data for the starting of the CO safety operation are provided for each gas type, a more correct and reliable CO safety operation can be performed. In this case, the information for the gas type select switch, which is provided for the ordinary water heater, is taken in to determine the type of gas which is used. The condition data for the starting of the CO safety operation which correspond to the gas type must be employed to perform the CO safety operation in the same manner as in this embodiment.
  • the adapter 403 is provided on the flue side of the water heater, and the double ventilation pipe unit and the dual ventilation pipe unit 404 are provided detachably replaceable.
  • the adapter 403 may be eliminated and either the double or dual ventilation pipe unit may be provided on the flue side of the water heater.
  • the condition data for the starting of the CO safety operation, both for the double pipe structure and for the dual pipe structure must be stored in the data memory 417 so that a water heater having either structure can be coped with at the installation site for the water heater.
  • a uni-functional water heater (a water heater having only a water heating function) has been explained as an example.
  • the present invention can be applied for various indoor types of combustion apparatus, such as one having a bath water heating function and a hot water supply function, one having a space heating function and a water heating function, one having a space cooling function and a water heating function, one having an air conditioning function and a water heating function, a bath water heater, a space heating appliance, a space cooling appliance, or an air conditioner.
  • Fig. 30 is a diagram illustrating the arrangement of a water heater which is one example combustion apparatus.
  • a hot water tap (not shown) is opened, water passes through a water flow rate sensor 512, and is branched to a heat exchanger 516 and to a bypass pipe 514.
  • the water flow rate sensor 512 detects the flow rate.
  • Air is drawn in through an air intake pipe 550, and following the starting of the combustion, a fan 524 is rotated to discharge exhaust gas through a flue pipe 552 and pre-purging is begun.
  • an ignition plug 518 is turned on, a main gas solenoid valve 528 and a gas solenoid valve 530 are opened, and gas flows through a gas proportioning valve 532.
  • a frame rod 520 detects a flame and combustion is begun. Water which is heated by the heat exchanger 516 and water which passes through the bypass pipe 514 are mixed, and as a result, hot water is fed to the hot water tap.
  • the opening of the gas proportioning valve 532 and the revolutions of the fan 524 are controlled so that the temperature of a hot water thermistor 536 reaches a set temperature.
  • a safety circuit is activated to close the main gas solenoid valve 528 and the gas solenoid valve 530, and to stop charging.
  • a Hall IC 526 for detecting the revolutions of the fan 524 is attached to the fan 524.
  • the fan 524 is so rotated that it feeds an adequate volume of air to the burner 522 in order to perform a complete combustion in accordance with the volume of the gas which is supplied.
  • the control of the combustion is exercised by an electric board 560, the controller.
  • a microcomputer which is constituted by a RAM, a ROM and a CPU, for example, is mounted on the electric board 560, and the CPU controls the combustion in accordance with a combustion program stored in the ROM.
  • a CO sensor 540 is located in the flue pipe.
  • the CO sensor 540 is constituted by a platinum resistor which has at its periphery a specific catalyst which can produce CO gas and a chemical reaction.
  • the catalyst generates a CO gas and causes a chemical reaction
  • the temperature of the catalyst rises, and the resistance of the platinum resistor, which changes in accordance with a change in the temperature, is compared with that of a comparator, and the resistance is re-calculated to conform to the density of the CO.
  • the CO sensor 540 detects that the CO gas density exceeds a permissible value, first the number of revolutions of the fan 524 is increased, and the air flow rate fed into the combustion chamber is increased, the rotation of the fan being controlled so that complete combustion is performed. When the CO gas density is not reduced, even though the air flow rate is increased and the CO gas density exceeds a predetermined value, the combustion is stopped.
  • the volume of exhaust gas generated through such combustion is varied in accordance with the revolutions of the fan 524. That is, when the number of revolutions of the fan is larger, the exhaust volume is increased, and when the number of revolutions of the fan is smaller, the exhaust volume is reduced.
  • the ER value is a value which depends not only on the density of the CO in the exhaust gas, but also on the volume of the exhaust gas.
  • a combustion apparatus which monitors the density of the CO in the air in accordance with the ER value, which is obtained while taking into account not only the CO density of the exhaust gas but also the number of revolutions of the fan, which is substantially proportional to the volume of the exhaust transmitted along the exhaust pipe 552.
  • Fig. 31 is a flowchart showing the processing for the monitoring of the density of the CO according to the first mode of the fifth embodiment.
  • the following processing for monitoring the CO density is performed by the electric board 560, which is the controller for the combustion apparatus.
  • step S510 the density of the CO in the exhaust gas is detected, and at step S516 the number of revolutions of the fan is detected.
  • the exhaust gas CO density is detected every 0.2 second by the CO sensor 540, and the revolutions of the fan are detected every 0.1 second by the Hall IC.
  • the predetermined time unit t is required to obtain the average value, and an arbitrary time can be set.
  • the time unit t at step S518 is synchronous with the time unit t at step S514.
  • the maximum number of revolutions is selected during the time unit t (step S520). Since a momentary change in the number of revolutions of the fan during the combustion is smaller than the change in the CO density, the calculation of the average is not actually required, and the maximum number of revolutions is employed from the point of view of safety. However, the average value may of course be employed to provide more accurate control.
  • a corresponding ER value is obtained from the table for the ER values which are entered in accordance with the average value of the CO densities and the maximum number of revolutions of the fan.
  • An example table is shown in Fig. 32. This table is stored in the ROM of the microcomputer, which is mounted on the electric board 560 in Fig. 30 which controls various combustion operations performed by the above described combustion apparatus.
  • different ER values are entered for the different number of revolutions of the fan (the exhaust volume) at the same CO density. In other words, when the number of revolutions of the fan is large, the exhaust volume is large, as is also the ER value. When the number of revolutions of the fan is small, the exhaust volume is small, as is also the ER value. For the same reason as described above, the ER values entered in Fig. 32 are to be multiplied by 250.
  • the ER value which is selected at step S522 is accumulated to calculate the TR value.
  • a warning is issued using a lamp or a buzzer (step S530), and the combustion is stopped (step S532).
  • the CO density monitoring processing may include an attenuation compensation process (not shown) in order to compensate for a temporary reduction in the CO density in the air, which, for example, is caused when the combustion is temporarily stopped during the addition of the ER values.
  • an attenuation compensation process (not shown) in order to compensate for a temporary reduction in the CO density in the air, which, for example, is caused when the combustion is temporarily stopped during the addition of the ER values.
  • the ER value is obtained using the number of revolutions of the fan, which is substantially proportional to the volume of the exhaust gas which is taken into account.
  • the volume of the exhaust gas may be detected by an air flow rate sensor located along the exhaust pipe, and a corresponding ER value may be obtained.
  • a second mode of the fifth embodiment will now be described.
  • a combustion apparatus which monitors the density of CO in the air in accordance with the ER value which is obtained, while taking into account not only the density of the CO in the exhaust gas but also the volume of a room into which exhaust gas which are travelling along the exhaust pipe may leak.
  • Fig. 33 is an example table of ER values in accordance with the average value of the CO densities corresponding to a plurality of spaces which have different volumes. For the previous mode, this table is stored in storage device, such as the ROM of the microcomputer mounted on the electric board 560. In Fig. 33, if the exhaust gas CO densities are the same, the ER value becomes smaller as the volume of the room into which the exhaust gas is discharged becomes larger. The volume of the space is set in advance by a select switch (not shown) which is provided for the combustion apparatus.
  • the ER value for the indoor space having the smallest volume be employed to set the volume for the space.
  • the space may be defined by breaking it into more segments than those shown in Fig. 33.
  • the processing for monitoring the CO density in this mode is performed substantially in the same manner as shown in the flowchart in Fig. 31. Although the processes at steps S516, S518 and S520 in Fig. 31 are not performed, at step S522 a corresponding ER value is acquired from the ER value table in Fig. 33 which is provided for this mode.
  • a combustion apparatus which monitors the density of the CO in the air in accordance with the ER value obtained while taking into account both the volume of the exhaust gas and the volume of the space.
  • Fig. 34 are example tables for ER values which correspond to the numbers of revolutions of the fan, which were explained for the first mode of the fifth embodiment, for the volumes of individual spaces, as explained for the second mode of the fifth embodiment. As in the previous mode, this table is stored in storage device, such as the ROM of the microcomputer on the electric board 560.
  • the microcomputer selects from the table, for the designated volume, the ER value which corresponds to the number of revolutions of the fan.
  • a corresponding ER value is acquired from an ER value table in Fig. 34 which is provided for this mode.
  • the tables as shown in Fig. 34 are stored in the memory for the double ventilation pipe structure, for the dual ventilation pipe structure and for the gas types, and adequate tables are selected so that an optimal CO safety operation can be performed.
  • the present invention assuming that exhaust gas is leaking into a room, data for calculating the danger time before a person in the room enters the critical condition caused by CO poisoning are provided for one or more combustion capabilities or exhaust volumes.
  • data for calculating the danger time before a person in the room enters the critical condition caused by CO poisoning are provided for one or more combustion capabilities or exhaust volumes.
  • information concerning the combustion capability and the exhaust volume is obtained, and the CO safety operation is performed based on a corresponding danger time. Therefore, the accuracy of the CO safety operation can be considerably increased, and the combustion operation will not be stopped even though the person in the room does not yet enter the critical condition caused by CO poisoning, so that a more dependable CO safety operation can be performed.
  • an equation for calculation of the indoor density is provided by using information for the detected density of CO of the exhaust gas and with the indoor volume and the combustion time being as parameters, and the indoor CO density is calculated using the equation. Therefore, since a simple form of the equation for calculating the indoor CO density can be provided by using the value of the CO density in the exhaust gas, a large computer is not required, and a microcomputer mounted on the combustion apparatus is satisfactory to obtain the precise indoor CO density.
  • the precise indoor CO density can be obtained regardless of the size of the indoor volume.
  • the accuracy of the CO safety operation can be performed, and the CO safety operation is more dependable.
  • the present invention when it is assumed that the exhaust gas leak indoor, data to obtain the danger time until the person in the room enters in the critical condition for CO poisoning are provided for one or more gas types.
  • data to obtain the danger time until the person in the room enters in the critical condition for CO poisoning are provided for one or more gas types.
  • information for the gas type which is employed is obtained, and the CO safety operation is performed based on the danger time which corresponds to that gas type. Therefore, since the accuracy of the CO safety operation is considerably increased, the combustion operation will not be stopped even though the person in the room does not enter yet the critical condition of CO poisoning, and a more dependable CO safety operation can be provided.
  • condition data for starting the CO safety operation are provided which corresponds to the ventilation pipe structure. Accordingly, the CO safety operation is performed based on the condition data for starting the CO safety operation in accordance with the ventilation pipe structure which is actually employed for the combustion apparatus, either the double pipe structure or the dual pipe structure. As a result, the accuracy of the CO safety operation can be drastically increased, and a more dependable CO safety operation can be provided.
  • the ER value is determined while taking into account not only the CO density in the exhaust gas, but also the exhaust volume produced by the number of revolutions of the fan, the volume of the space into which exhaust gas is discharged, the ventilation pipe structure, and/or the gas type, an accurate ER value which corresponds to the actual combustion operation can be obtained, and more precise and dependable CO density monitoring processing can be implemented.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Regulation And Control Of Combustion (AREA)
EP97930779A 1996-07-17 1997-07-14 Appareil de combustion Withdrawn EP0913644A1 (fr)

Applications Claiming Priority (11)

Application Number Priority Date Filing Date Title
JP206640/96 1996-07-17
JP20664096A JP3727418B2 (ja) 1996-07-17 1996-07-17 燃焼機器のｃｏ安全装置
JP20664196A JPH1030817A (ja) 1996-07-17 1996-07-17 燃焼機器およびそのｃｏ安全動作方法
JP206641/96 1996-07-17
JP20901796A JPH1038270A (ja) 1996-07-19 1996-07-19 Ｃｏ安全装置付燃焼機器およびそのｃｏ安全動作方法
JP209017/96 1996-07-19
JP21801796A JP3691599B2 (ja) 1996-07-31 1996-07-31 燃焼機器
JP218017/96 1996-07-31
JP28641896A JP3810153B2 (ja) 1996-10-29 1996-10-29 Ｃｏ濃度監視方法及びそれを実施する燃焼装置
JP286418/96 1996-10-29
PCT/JP1997/002429 WO1998002693A1 (fr) 1996-07-17 1997-07-14 Appareil de combustion

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EP0913644A1 true EP0913644A1 (fr) 1999-05-06

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Application Number Title Priority Date Filing Date
EP97930779A Withdrawn EP0913644A1 (fr) 1996-07-17 1997-07-14 Appareil de combustion

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EP (1) EP0913644A1 (fr)
WO (1) WO1998002693A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1999345A2 (fr) * 2006-03-29 2008-12-10 The North American Manufacturing Company, Ltd. Mode de conformité garanti pour le fonctionnement d'un système de combustion

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Publication number Priority date Publication date Assignee Title
JPH0623609B2 (ja) * 1989-05-10 1994-03-30 リンナイ株式会社 燃焼安全装置
JP2940646B2 (ja) * 1991-07-19 1999-08-25 パロマ工業株式会社 燃焼機器の不完全燃焼防止装置
JPH0646164U (ja) * 1992-11-30 1994-06-24 株式会社ガスター 燃焼機器の安全装置
JPH08178281A (ja) * 1994-12-28 1996-07-12 Tokyo Gas Co Ltd 対ｃｏガス安全システム

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* Cited by examiner, † Cited by third party
Title
See references of WO9802693A1 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1999345A2 (fr) * 2006-03-29 2008-12-10 The North American Manufacturing Company, Ltd. Mode de conformité garanti pour le fonctionnement d'un système de combustion
EP1999345A4 (fr) * 2006-03-29 2014-07-30 Fives North American Comb Inc Mode de conformité garanti pour le fonctionnement d'un système de combustion

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