EP0781966A1 - Verbrennungsanlage zur überwachung von fehlern oder lebensdauer - Google Patents

Verbrennungsanlage zur überwachung von fehlern oder lebensdauer Download PDF

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Publication number
EP0781966A1
EP0781966A1 EP95930007A EP95930007A EP0781966A1 EP 0781966 A1 EP0781966 A1 EP 0781966A1 EP 95930007 A EP95930007 A EP 95930007A EP 95930007 A EP95930007 A EP 95930007A EP 0781966 A1 EP0781966 A1 EP 0781966A1
Authority
EP
European Patent Office
Prior art keywords
air
flow rate
combustion
detected
burner
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Withdrawn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
EP95930007A
Other languages
English (en)
French (fr)
Inventor
Masanori Enomoto
Naoto Tominaga
Masato Kondo
Tatsuo Fujimoto
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 JP23073294A external-priority patent/JP3566757B2/ja
Priority claimed from JP24956594A external-priority patent/JP3566758B2/ja
Priority claimed from JP28440394A external-priority patent/JP3566765B2/ja
Application filed by Gastar Co Ltd filed Critical Gastar Co Ltd
Publication of EP0781966A1 publication Critical patent/EP0781966A1/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • 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
    • F23N5/242—Preventing development of abnormal or undesired conditions, i.e. safety arrangements using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel
    • F23N5/184—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2223/00—Signal processing; Details thereof
    • F23N2223/08—Microprocessor; Microcomputer
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2225/00—Measuring
    • F23N2225/04—Measuring pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2227/00—Ignition or checking
    • F23N2227/12—Burner simulation or checking
    • F23N2227/16—Checking components, e.g. electronic
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2231/00—Fail safe
    • F23N2231/26—Fail safe for clogging air inlet
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2233/00—Ventilators
    • F23N2233/06—Ventilators at the air intake
    • F23N2233/08—Ventilators at the air intake with variable speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2235/00—Valves, nozzles or pumps
    • F23N2235/12—Fuel valves
    • F23N2235/18—Groups of two or more valves

Definitions

  • the present invention relates to a combustion appliance, such as a water heater, a bath water heater or a space heating appliance, that controls an air-flow rate from the output of an air-flow rate sensor and a fuel supply quantity to perform combustion control for reducing exhausting volumes of toxic substances, such as carbon monoxide, hydrocarbon and nitrogen oxides.
  • a combustion appliance such as a water heater, a bath water heater or a space heating appliance, that controls an air-flow rate from the output of an air-flow rate sensor and a fuel supply quantity to perform combustion control for reducing exhausting volumes of toxic substances, such as carbon monoxide, hydrocarbon and nitrogen oxides.
  • Fig. 15 is shown the system configuration of a common water heater as an example combustion appliance.
  • a burner 2 is located in the lower portion of a combustion chamber 1, and a combustion fan 3 is located beneath the burner to supply air and remove exhaust gasses.
  • a revolution count sensor is provided for the combustion fan 3.
  • a heat exchanger 4 for the supply of hot water is located in the upper portion of the combustion chamber 1.
  • a water supply pipe 5 is connected to the input of the heat exchanger 4, and an input water temperature sensor 6, such as a thermistor, for detecting the temperature of the input water, and a water volume sensor 7 for detecting the flow rate of the input water, are provided along the water supply pipe 5.
  • a hot water supply pipe 8 is connected to the output of the heat exchanger 4.
  • Solenoid valves 13 and a proportional control valve 14 for controlling the volume of the gas supplied are located along a gas supply way 12 of the burner 2.
  • Pressure induction inlets for pressure induction pipes 20a and 20b of a differential pressure sensor 16, which serves as an air-flow rate sensor, are provided at the lower portion of the burner 2 and in a flueway 19. A difference between the pressures induced along the pressure induction pipes 20a and 20b in the lower portion of the burner 2 and in the flueway 19 is detected by the differential pressure sensor 16.
  • a sequential program for controlling the operation of a water heater is incorporated in a controller 15.
  • the controller 15 also has a control circuit for controlling the operation according to the sequential program.
  • the controller 15 receives information from the input water temperature sensor 6, the water flow rate sensor 7, the output hot water temperature sensor 10, the differential pressure sensor 16, and a remote controller (not shown), and controls the operations of the solenoid valves 13, the proportional control valve 14, the combustion fan 3, and the water flow rate control valve 11 to perform water heating and to supply hot water.
  • Water passing through the heat exchanger 4 is heated by the burner 2 to a temperature set by a remote controller, etc.
  • the hot water that is output by the heat exchanger 4 at the set temperature is supplied along the hot water supply pipe 8 to a desired location, such as a kitchen or a bathroom.
  • the controller 15 controls the revolution of the combustion fan 3 in consonance with the combustion potential (combustion volume) of the burner 2.
  • combustion control data concerning a gas supply volume and a combustion potential shown in Fig. 12
  • fan revolution control data concerning an air-flow rate (fan revolutions) and a combustion potential shown in Fig. 13.
  • a required calorific value for increasing the input water temperature to the set temperature is continuously calculated by a calculation circuit in the controller 15.
  • the degree of opening for the proportional control valve 14, i.e., the gas supply volume is adjusted in consonance with the combustion potential for the required calorific value and the data shown in Fig. 12.
  • the degree of opening for the valve is controlled by a valve opening current which is fed to the proportional control valve 14.
  • the revolution rate of the fan is controlled so as to maintain an air-flow rate that corresponds to the combustion potential and the data shown in Fig. 13, and the optimal air volume for burner combustion is supplied to the burner 2.
  • the air-flow rate is controlled based on a differential pressure detection signal output by the differential pressure sensor 16. More specifically, provided for the controller 15 are those data shown in Fig. 14 concerning the relationship between the differential pressure for the differential sensor 16 and the air-flow rate (the volume of air). The actual air-flow rate is acquired in accordance with the differential pressure value detected by the differential pressure sensor 16. Then, a difference between the required air-flow rate and the actually detected air-flow rate is calculated. The revolution rate of the combustion fan 3 is adjusted so as to correct for the difference and reduce it to zero, so that an air-flow rate that is appropriate for the combustion volume is supplied.
  • the water heater may be discarded when it is determined, in consonance with reference values for ignition times and for total combustion time, that its useful lifetime has expired. In this case, it would not be an effective and economical use of the water heater.
  • the present invention focuses on the use of the differential pressure sensor 16 to control the air-flow rate of the combustion fan 3, and is related to a combustion appliance that can precisely detect the malfunctioning or the expiration of lifetime of a water heater by using a differential pressure detection signal from the differential pressure sensor 16.
  • the differential pressure sensor 16 is hereinafter referred to as an air-flow rate sensor 16.
  • Fig. 16 is a graph showing the relationship between the air-flow rate (the output measured by the air-flow rate sensor 16) and the revolution rate by the combustion fan. As is indicated by the solid line in the graph, the revolution rate of the combustion fan 3 required to obtain a specified air-flow rate is precisely acquired. As is described above, when the air flow resistance is increased, however, the revolution rate of the combustion fan 3 required to obtain a specified air-flow rate is also increased. That is, when the combustion fan 3 is rotated at a specified revolution rate, an air flow to be supplied is reduced.
  • the present inventors focused on that it can be determined that a malfunction, such as the expiration of the lifetime, of the combustion appliance has occurred when the relationship between the air-flow rate and the revolution rate of the combustion fan 3 becomes shifted to a certain degree from an appropriate relationship, then the air flow resistance is changed.
  • the present inventors also found that the movement of air outside the location where the combustion appliance is installed affects the output reading obtained by the air flow sensor 16 through the flueway 19.
  • the combustion appliance may not be necessarily discarded if only the relationship between the air-flow rate and the revolution rate of the combustion fan 3 is changed from the normal condition. In other words, even when the air-flow rate is reduced under the maximum revolution rate of the combustion fan 3, if the capability of the combustion is reduced, an air flow corresponding to the reduced combustion capability may be able to be supplied.
  • the basic principle of the present invention is that, when no movement of external air or no wind has been confirmed, the output value from the air-flow sensor and the output value of a fan revolution rate detector are monitored to detect an abnormality or the expiration of the lifetime. Therefore, a first method is used for monitoring an air-flow rate detected by an air flow sensor while a combustion fan is halted or rotated at a specified revolution rate, and a second method is used for monitoring the revolution rate detected by a fan revolution rate detector while a combustion fan is so rotated that the air-flow rate detected by an air-flow rate sensor is maintained at a specified value.
  • the principle is the same for either method, and the arrangements of the present invention required for the use of both methods will, now be alternately explained.
  • a combustion appliance comprises:
  • a combustion appliance comprises:
  • a combustion appliance comprises:
  • a combustion appliance comprises:
  • the relationship between the air-flow rate and the revolution rate of the combustion fan during no wind condition can be appropriately monitored, and an abnormality or expiration of a lifetime can be appropriately detected.
  • a combustion appliance comprises:
  • a combustion appliance comprises:
  • the detection that there is no movement of external air and detection that the relationship between an air-flow rate and a fan revolution rate is shifted from an appropriate value can be simultaneously performed.
  • the combustion appliance according to the second or the third invention further comprises a fuel controller for feeding sufficient fuel to the burner to supply a required caloric value.
  • a fuel controller for feeding sufficient fuel to the burner to supply a required caloric value.
  • a first reference air-flow rate and a second reference air-flow rate that is lower than the first reference air-flow rate.
  • the supply of the fuel to the burner is forcibly reduced by the fuel controller.
  • the air-flow rate detected by the air-flow rate is lower than the second reference air-flow rate, the supply of the fuel to the burner is halted by the fuel controller.
  • the combustion appliance according to the second or the third invention further comprises a fuel controller for providing an adequate supply of fuel to the burner to maintain a required caloric value.
  • a fuel controller for providing an adequate supply of fuel to the burner to maintain a required caloric value.
  • a first reference revolution rate and a second reference revolution rate that is higher than the first reference revolution rate.
  • the supply of the fuel to the burner is forcibly reduced by the fuel controller.
  • the revolution rate detected by the revolution detector is higher than the second reference revolution rate, the supply of the fuel to the burner is halted by the fuel controller.
  • the operation can be continued and incomplete combustion can be avoided by forcibly reducing the supply of fuel.
  • a combustion appliance comprises:
  • a combustion appliance comprises:
  • the fifth invention since an initial value for an air-flow rate is stored in a combustion appliance that has been installed, sensitivity of the air-flow rate sensor that differs depending on the combustion appliance and on the installation environment can be adjusted.
  • a combustion appliance comprises:
  • the sixth invention since a zero point correction or calibration associated with a secular change or age change of the air-flow rate sensor can be performed without being affected by an external movement of air, the occurrence of an abnormality or the expiration of a lifetime can be appropriately determined by employing the air-flow rate sensor.
  • a combustion appliance comprises:
  • a combustion appliance comprises:
  • detection of a condition during which there is no wind condition, and detection of an abnormality or of the expiration of a lifetime can be easily performed at the same time through simply determining whether or not there is any movement of air.
  • an air-flow rate detected by an air-flow rate sensor 16 is referred to simply as a detected air-flow rate or an air-flow rate sensor output.
  • its direct output can be either a voltage value or another physical quantity. Regardless of what physical quantity, it is apparent that the air-flow rate detection value output by the air-flow rate sensor, or simply the output of the air-flow rate sensor, means an air-flow rate that has been detected.
  • the output of a combustion fan revolution rate detector, or a revolution rate detection value means a revolution rate that has been detected
  • Fig. 3 Shown in Fig. 3, as an example combustion appliance according to the present invention, is a water heater that has means for determining the occurrence of an abnormality or the expiration of its lifetime.
  • the water heater in this embodiment has a burner 2, the combustion capability of which can be switched.
  • the combustion stages of the burner 2 are defined as stages A, B and C.
  • the combustion for stage A is performed by opening only a capability switching valve 18a, which is a solenoid valve, etc.
  • capability switching valves 18a and 18b When capability switching valves 18a and 18b are opened, a two-stage combustion operation for stages A and B is performed.
  • capability switching valves 18a, 18b and 18c When capability switching valves 18a, 18b and 18c are opened, a full combustion operation for stages A, B and C is provided.
  • the combustion capability of the burner 2 can be changed by switching these capability switching valves 18a, 18b and 18c.
  • the combustion changes for the burner 2, i.e., the switching of the capability switching valves 18a, 18b and 18c, is controlled by a controller 15.
  • a differential pressure sensor 16 serving as an air-flow rate sensor, detects a differential pressure between the upper and lower sides of the burner 2.
  • the revolution rate for a combustion fan 3 is detected by a fan revolution rate sensor 28, such as a Hall IC.
  • the controller 15 has a means for determining whether or not an operating abnormality or the expiration of its lifetime of the water heater has occurred, in addition to the control of an air-flow rate for the combustion fan 3, which is based on a value detected by the differential pressure sensor 16, an air flow sensor.
  • the differential pressure sensor 16 used in this embodiment is substantially an air-flow rate sensor, and for convenience is hereinafter referred to as an air-flow rate sensor.
  • the characteristic means for determining whether or not an abnormality or the expiration of a unit lifetime has occurred includes a condition determiner 22, a memory 23, a combustion stop unit 24, a fan re-activator 25, an abnormality/lifetime determiner 26, and a timer 27. These components are functional parts of the controller 15.
  • the set revolution rate for the fan is determined as needed, in this embodiment it is set to the rated maximum revolution rate for the combustion fan 3, and an air-flow rate obtained at the rated maximum revolution rate is stored.
  • the condition determiner 22 identifies a stable, condition in which there is no wind and a windy condition for an appliance installation environment at a time when there are zero revolutions of the combustion fan 3, i.e., when the combustion fan 3 is not revolving.
  • Fig. 4 is a graph showing the relationship, of the magnitude of a wind speed to the output of the air-flow rate sensor 16, that is obtained by an experiment when the water heater is exposed in the windy condition. As is apparent from the graph, in the windy condition the detected points for the air-flow rates detected by the air-flow rate sensor 16 are asymmetrically positioned in the upper and lower portions relative to the zero point of the sensor 16. The width of this fluctuation is increased as the wind speed is increased.
  • the condition determiner 22 compares the air-flow rate detected by the air-flow rate sensor 16 when there are zero revolution rate of the combustion fan 3, or the fluctuation width of the air-flow rate with a permissible range stored in the memory 23.
  • the permissible range is set to determine whether there is a windy condition or a no-wind condition, depending on whether the fluctuation width of the air-flow rates is equal to or greater than a predetermined value, or that it is equal to or less than a predetermined value.
  • the windy condition is determined, for example, by examining whether or not the fluctuation width of the detected air-flow rate exceeds a predetermined permissible value.
  • the windy condition can also be easily determined by examining the detected air-flow rate to determine whether it exceeds a predetermined absolute value.
  • the condition determiner 22 When a specified fan revolution rate, which is set in advance, is detected by the fan revolution rate sensor 28 in a condition where there is no combustion, the condition determiner 22 operates the timer 27 for a predetermined period of time. During the timer operation period, the condition determiner 22 compares the air-flow rate provided by the air-flow rate sensor 16 with the reference air-flow rate stored in the memory 23. When the detected air-flow rate is outside the permissible range, the condition determiner 22 detects that there is a windy condition. When the detected air-flow rate is within the permissible range, the condition determiner 22 detects that there is a stable, no-wind condition, and transmits the results to the combustion stop section 24 and the abnormality/lifetime determiner 26.
  • the combustion stop section 24 When, in the combustion operation where the combustion fan 3 is revolving at the rated maximum revolution rate, the combustion stop section 24 receives a result from the condition determiner 22 indicating that the detected air-flow rate is lower than the reference air-flow rate, the combustion stop section 24 halts the combustion at the burner 2 and transmits a combustion stop signal to the fan re-activator 25.
  • the fan re-activator 25 Upon receipt of the combustion stop signal from the combustion stop section 24, the fan re-activator 25 activates the combustion fan 3 at the set revolution rate, i.e., the rated maximum revolution rate, without any combustion at the burner 2, and transmits a fan re-activation signal to the abnormality/lifetime determiner 26.
  • the abnormality/lifetime determiner 26 determines whether an abnormality or the expiration of the lifetime of a water heater has occurred when the condition determiner 22 has ascertained that there is a stable, no-wind condition, and when the detected air-flow rate is equal to or lower than the reference air-flow rate while the combustion fan 3 is being rotated at the rated maximum revolution rate. An abnormality/lifetime signal is thereafter output.
  • the condition determiner 22 determines there is a windy condition, or when the detected air-flow rate exceeds the reference air-flow rate, even though there is a stable, no-wind condition, the abnormality/lifetime determiner 26 ascertains that no abnormality has occurred in the water heater, or that the lifetime of the water heater has not yet expired, and an abnormality/lifetime signal is not output.
  • Fig. 2 is a circuit diagram illustrating an operation controller for a water heater when an abnormality/lifetime signal is output by the abnormality/lifetime determiner 26.
  • This circuit includes a combustion capability down switching section 31, a capability characteristic graph selector 32, a fan controller 34, and a water flow rate controller 33.
  • the water heater for which an abnormality has occurred or for which the lifetime has expired can be discarded.
  • the circuit shown in Fig. 2 enables such a water heater to be used temporarily until it is replaced by a new one, instead of immediately discarding it when an abnormality/lifetime signal has been output.
  • the combustion capability down switching section 31 reduces the combustion capability of the water heater by one level to avoid incomplete combustion at the burner 2 for an air-flow rate of the combustion fan 3.
  • the combustion capability down switching section 31 Upon receipt of an abnormality/lifetime signal, the combustion capability down switching section 31 reduces the combustion capability of, for example, a size 24 water heater (output 36,000 kcal/h) to that of, for example, a size 20 (output 30,000 Kcal/h).
  • the reduced combustion capability is transmitted to the capability characteristic graph selector 32 and to the water flow rate controller 33. To reduce the combustion capability, only the fuel fed to the burner 2 need be reduced.
  • Control characteristic data for three-stage combustion capacities are provided for the capability characteristic graph selector 32.
  • the characteristic line D 1 is a characteristic line at the first stage combustion for the combustion stage A of the burner 2;
  • D 2 a characteristic line at the second-stage combustion for combustion stages A and B of the burner 2;
  • D 3 a characteristic line for the three-stage combustion for stages A, B and C.
  • Overlapping portions ⁇ D and ⁇ D' are provided between the characteristic lines for the individual stages to smoothly perform conversion of the characteristic lines D 1 , D 2 and D 3 .
  • the start end position D s of the characteristic line D 1 is the minimum capability point.
  • the combustion capability is gradually increased until it reaches the maximum combustion capability for the first stage, which is the end position D F of the characteristic line D 1 .
  • the capability of the burner 2 is switched to the two stage combustion of the stages A and B.
  • the combustion characteristic line is changed from point D f of the line D 1 to point D P of the line D 2 , and combustion is controlled according to the characteristic line D 2 .
  • the combustion capability down switching section 31 changes the combustion capability in the lower direction, and the fuel supply volume (proportional control valve current) on the right of the line L in Fig. 5A is cut off. Then, the overlapping portions ⁇ D and ⁇ D', between the characteristic lines D 1 , D 2 and D 3 , disappear, and switching of the combustion characteristic lines can not be performed smoothly.
  • the capability characteristic graph selector 32 selects the character line for a smaller combustion capability (selects D1 when required combustion capability P is located between the lines D 1 and D 2 in Fig. 5B), and combustion is controlled according to the selected characteristic line.
  • the water flow rate controller 33 compares a temperature set by a remote controller, etc., with an output hot water temperature detected by an output hot water temperature sensor 10. When the output water temperature detected by the output water temperature sensor is lower than the set temperature, the water flow rate controller 33 so restricts the water flow control valve 11 that, through the control valve 11, hot water is output at the set temperature. In other words, since the combustion capability is reduced, the amount of hot water is also reduced to maintain the set temperature.
  • a first operation for this embodiment will now be described while referring to the flowchart in Figs. 6 and 7.
  • the schematic flow for the first operation is as follows. When it is found during combustion that the air-flow rate detected by the air-flow rate sensor is reduced, combustion is temporarily halted and a diagnostic operation is performed. During the diagnostic operation, first, a fan is re-activated. When the air-flow rate detected for a specified revolution rate of the fan is within a predetermined range for a predetermined time period, it is assumed that there is no wind condition, and a check is performed to determine whether or not the current air-flow rate is lower than the reference air-flow rate. When the current air-flow rate is lower than the reference air-flow rate, the following combustion is continued in the combustion capability down mode.
  • the same diagnostic operation is repeated.
  • the current air-flow rate is lower than the reference air-flow rate, it is assumed that the lifetime of the appliance has expired and combustion is inhibited.
  • a zero is set as an initial value for an abnormality/lifetime decision flag (LIFE). Since the processing at steps 102 through 120 is for normal combustion control, this processing will be explained only briefly.
  • LIFE abnormality/lifetime decision flag
  • water input is confirmed in accordance with a signal from the water flow rate sensor 7.
  • a feedforward (FF) caloric value which is required for raising the input water temperature to the set temperature, is calculated; the ON/OFF states of the capability switching valves 18a through 18c are determined; the degree of opening of a proportional control valve is determined, and a proportional control valve current that corresponds to the degree of opening is supplied; a combustion fan is rotated at a pre-purge revolution rate; and the solenoid valve 13 is rendered on.
  • a check is performed to determine whether or not a pre-purge period has elapsed.
  • the revolution rate for the combustion fan is increased to a revolution rate for an ignition attempt, and the switching capability valve and an igniter are rendered on.
  • the ignition by a flame rod (not shown) was performed, and at step 112, the igniter is turned off.
  • step 108 a check is performed to determine whether or not the time period for the ignition attempt has elapsed. When the ignition period has not yet elapsed, the ignition attempt is repeated. When ignition is not confirmed even though it has been attempted, at step 109 the solenoid valve, the capability switching valves, and the proportional control valve are set to off. It is then ascertained that a hot water plug (not shown) at the distal end of a hot water pipe 8 is closed so that the water-flow rate sensor 7 does not detect a water flow. At step 111, the combustion fan is halted to await re-opening of the hot water plug.
  • step 113 a check is performed to determine whether or not a zero is set for the abnormality/lifetime determination flag.
  • program control advances to step 114 whereat combustion operation is performed by both the feedforward (FF) control and the feedback (FB) control for a gas volume, and by the water flow rate control using the water flow rate control valve.
  • a check is performed to determine whether or not the air-flow rate is appropriate for the burner combustion volume.
  • the relationship I K ⁇ P is established between the opening degree of the proportional control valve 14, i.e., the valve opening current I, and the air-flow rate.
  • ⁇ P defines a differential pressure at an interval between the upper and the lower air passages, and corresponds to an air-flow rate.
  • K is a proportional constant and is set in advance.
  • this is an ideal combustion that is close to complete combustion, and less carbon monoxide, hydrocarbon, and nitrogen oxides are discharged in the exhaust.
  • the valve opening current I is compared with the air-flow rate information K ⁇ P.
  • I is smaller than K ⁇ P, it is assumed that the air-flow rate is too high relative to the degree of opening of the proportional control valve 14, i.e., the gas supply volume. In this case, at step 118, the revolution rate for the combustion fan 3 is reduced.
  • a check is performed to determine whether the fan revolution rate is equal to or greater than the rated maximum revolution rate.
  • the fan revolution rate has not reached the rated maximum revolution rate (upper limit value)
  • the fan revolution rate can be increased.
  • the fan revolution rate is increased to compensate for an insufficient air-flow rate.
  • the air-flow rate is insufficient (air volume is insufficient).
  • a check is performed to determine whether a zero is set to the abnormality/lifetime flag. Since at step 101 a zero has been set to the flag, as described above, program control moves to the process at step 122, where the solenoid valve 13, the capability switching valves 18a through 18c and the proportional control valve 14 are rendered off to halt the combustion at the burner 2.
  • the combustion fan 3 is rotated in accordance with the set control condition, i.e., at the rated maximum revolutions in this example.
  • the air-flow rate ⁇ P detected by the air-flow rate sensor 16 is compared with the reference air-flow rate B mmAq.
  • sampling of the detected air-flow rate is repeatedly performed, and the result is compared with the reference air-flow rate.
  • the condition determiner 22 determines that a condition exists in which there is no wind condition. Since an insufficient air-flow rate occurs even when there is no wind movement, it is detected that deterioration occurred due to ventilation blockage, such as the plugging of the water heater 4 with soot.
  • the abnormality/lifetime determiner 26 determines that an abnormality occurred in the appliance or that the lifetime of the appliance has expired, and a "1" is set to the abnormality/lifetime determination flag.
  • the detected air-flow rate ⁇ P is higher than the reference air-flow rate even once during the timer operation period (C minutes)
  • determination of a stable, no wind condition and determination of the occurrence of an abnormality or the expiration of the lifetime of an appliance are performed at the same time.
  • the reference air-flow rate is calculated based on, for example, the limiting value at which the carbon monoxide, hydrocarbon, and nitride oxide contents of the exhaust gas will be increased if incomplete combustion is continued and if an air-flow rate is lower than the current rate.
  • Fig. 27 is a graph showing an example change in an air-flow rate when the fan was rotated at a specified revolution rate as time elapsed along the horizontal axis.
  • the reference air-flow rate constantly fluctuated due to the influence of the external movement of air, as is shown in Fig. 27.
  • the determination of the wind condition and the determination that an abnormality or the expiration of a lifetime has occurred can be performed at the same time by monitoring whether or not an air-flow rate lower than the reference air-flow rate B is continuously maintained for a specified period of time.
  • Fig. 28 is shown a change in the revolution rate for the combustion fan 3 that was recorded while the combustion fan 3 was so controlled that a constant air-flow rate was detected by the air-flow rate sensor.
  • the revolution rate detected by the fan revolution rate detector is maintained and is greater than the reference revolution rate B for a constant period of time is determined, so that the determination of the wind condition and the determination whether an abnormality or the expiration of a lifetime has occurred can be performed at the same time.
  • a signal to the effect that the appliance is operating abnormally or that its lifetime has expired is indicated by using a lamp, or is displayed on the screen of a remote controller, etc., to inform a user that an abnormality or the expiration of the lifetime of the appliance has occurred. In this manner, the user is notified that the performance of an appropriate procedure is required, such as the replacement or the maintenance of the appliance.
  • the occurrence of an abnormality or the expiration of the lifetime is determined at steps 122 through 126.
  • the abnormality/lifetime determination flag holds a zero.
  • a "1" is set for the abnormality/lifetime determination flag.
  • a hot water plug is opened and the process at steps 102 through 113 is performed.
  • a "1" is set for the abnormality/lifetime determination flag, it is assumed that the combustion operation was performed after the occurrence of an abnormality or the expiration of the lifetime of the appliance was detected.
  • the process at step 127 and the following steps in Fig. 7 are performed.
  • the operation at step 127 and the following steps is to enable the water heater to be used temporarily within the reduced range of the air-flow rate due to the occurrence of an abnormality or the expiration of the lifetime of the appliance.
  • the combustion capability of the water heater is reduced by a predetermined value, e.g., to 1/N, for each stage of the burner 2.
  • N is a real number that includes a decimal fraction. In other words, as is shown in Fig. 5A, the capability on the right side of the line L is cut.
  • a check is performed to determine whether or not the combustion capability obtained by feedforward calculation is available (feedforward gas control is enabled) relative to the set temperature.
  • step 115 When the combustion capability is available, the combustion operation at step 115 and the following is performed for the condition where the combustion capability is cut.
  • program control does not go to step 113, but moves to step 115 in consonance with the combustion capability that is reduced to 1/N, as is indicated by the broken line.
  • step 1208 it may be determined that the combustion capability acquired by feedforward calculation is not available. More specifically, as is shown in Figs. 5A and 5B, the capability on the right side of the line L is cut, the overlapping portions ⁇ D and ⁇ D' disappear between the characteristic lines for the stages, and as a result, a combustion capability at a drop portion between a characteristic line for a low capability and that for a higher capability is required. In this case, at step 129, the characteristic line for combustion control is shifted to the characteristic line for low combustion.
  • the water flow control valve 11 is controlled to reduce the output of hot water, and the water flow rate is adjusted so that hot water at the set temperature can be output.
  • the combustion operation at step 115 and the following is performed. Also in this case, if it is ascertained that the water flow state is ON at step 116, program control does not move to step 113 but goes to step 114.
  • the air-flow rate control is performed at steps 115 through 120.
  • the fan revolution rate is equal to or greater than the rated maximum revolution rate
  • a check is performed to determine whether or not the abnormality/lifetime determination flag is set to zero. Since in this stage the abnormality/lifetime determination flag has been set to "1" at step 131, the operation of the appliance is forcibly halted. The following combustion operation is thereafter inhibited, and as a result, incomplete combustion operation is avoided and safety is ensured.
  • Fig. 8 is a flowchart showing a second operation for determining whether an abnormality or the expiration of the lifetime of an appliance has occurred.
  • the schematic processing flow for the second operation is as follows.
  • an abnormal air-flow rate is detected during the combustion, the combustion is temporarily halted.
  • the wind condition is examined with no combustion and no revolution of a combustion fan.
  • the combustion fan is rotated at a predetermined revolution rate, and a check is performed to determine whether or not a satisfactory air-flow rate is obtained.
  • the examination of the wind condition, and the determination of whether an abnormality or the expiration of the lifetime has occurred were performed at the same time, at steps 123 through 125.
  • the examination of the wind condition and the determination of whether an abnormality or the expiration of the lifetime had occurred are performed separately.
  • the second operation is more preferable.
  • the other procedures are the same as those in the first operation, and the same step numbers as are used in the first operation are also used for those in the second operation.
  • the process is performed to determine what wind condition there is in the environment surrounding the installed appliance.
  • the process is performed to determine whether an abnormality or the expiration of the lifetime has occurred.
  • combustion is taking place, at step 119 it is ascertained that, although the revolution rate for the combustion fan is equal to or greater than the rated maximum revolution rate, the detected air-flow rate is insufficient relative to the volume of the gas supplied.
  • the combustion is halted at step 132 in order to determine whether the insufficiency of air is caused by some wind condition or by the occurrence of an abnormality or the expiration of the lifetime.
  • the solenoid valve, the capability switching valves and the proportional control valve are rendered off, and the combustion fan 3 is also halted.
  • Program control then moves to steps 133 through 139 to determine the wind condition status.
  • the output of the air-flow rate sensor 16 is affected by the wind condition and fluctuates widely, as was explained while referring to Fig. 4.
  • the variable output of the air-flow rate sensor 16 is monitored, while the rotation of the combustion fan and the combustion are halted.
  • step 133 maximum momentary value ⁇ P MAX and minimum momentary value ⁇ P MIN are input as initial data, and are stored in the memory 23.
  • step 134 a check is performed to determine whether the air-flow rate ⁇ P detected by the air-flow rate sensor 16 is equal to or greater than ⁇ P MAX . If the detected air-flow rate ⁇ P is greater than the maximum momentary initial value ⁇ P MAX , the detected value ⁇ P is replaced with the value ⁇ P MAX .
  • the detected air-flow rate ⁇ P is compared with the minimum momentary initial value ⁇ P MIN to determine whether the value ⁇ P is equal to or smaller than the value ⁇ P MIN . If the value ⁇ P is smaller than the value ⁇ P MIN , the ⁇ P is replaced with the value ⁇ P MIN .
  • the replacement of the maximum momentary value ⁇ P MAX and the minimum momentary value ⁇ P MIN is performed during a predetermined sampling time period designated by the timer 27, and the values ⁇ P MAX and ⁇ P MIN are established.
  • a difference (the width of the fluctuation) between the established values ⁇ P MAX and ⁇ P MIN is calculated to determine whether or not the difference is below the set permissible range.
  • the difference between the maximum momentary value ⁇ P MAX and the minimum momentary value ⁇ P MIN is equal to or exceeds the limit for the permissible range D, i.e., when the wind velocity causing the fluctuation in the air-flow rate detected by the air-flow rate sensor 16 is greater than the wind velocity corresponding to the permissible range D, it is detected that there is some wind condition, and it is assumed that the insufficient air volume is due to a temporary effect of the wind condition.
  • the processing at step 102 and the following is thereafter performed.
  • step 139 If, at step 139, the difference between the maximum momentary value ⁇ P MAX and the minimum momentary value ⁇ P MIN is less than D, it is ascertained that the condition is stable with no wind condition.
  • steps 140 and 141 processing is performed to determine whether an abnormality or the expiration of the lifetime of an appliance has occurred.
  • step 140 while the combustion at the burner 2 is being halted, the combustion fan 3 is rotated at the rated maximum revolutions that is the set control condition.
  • step 141 the detected air-flow rate ⁇ P is compared with the reference air-flow rate (B mmAq).
  • Figs. 9 and 10 are flowcharts showing a third operation according to the embodiment.
  • the feature of the third operation is that, after the appliance has been powered on by an operation switch, the wind condition is examined prior to initiating the rotation of the combustion fan, and determination of an abnormality or the expiration of the lifetime of an appliance has occurred is performed during the pre-purge fan rotation.
  • the same step numbers as are used for the first and the second operations are also used in the flowchart for the third operation to denote corresponding processes, and an explanation for these processes will not be given (or only a brief explanation will be given).
  • a zero is set for the abnormality/lifetime determination flag.
  • the initial values for the maximum momentary value ⁇ P MAX and the minimum momentary value ⁇ P MIN of the air-flow rate sensor 16 are input, and at the same time, a zero is set for a no-air-movement flag E.
  • the timer 27 for determining whether there is some wind condition or there is a stable is started (includes a reset start).
  • the processing is performed in the same manner as at steps 134 through 137 in Fig. 8 for the second operation.
  • the air-flow rate detected by the air-flow rate sensor 16 is employed to establish the maximum momentary value ⁇ P MAX and the minimum momentary value ⁇ P MIN during the period of time allocated for sampling.
  • a difference between the maximum momentary value ⁇ P MAX and the minimum momentary value ⁇ P MIN is compared with the limit set for the permissible range D.
  • step 307 The determination of the wind condition is repeated until at step 307 an ON signal is transmitted by the water flow rate sensor 7.
  • program control moves to step 104.
  • pre-purge rotation of the combustion fan 3 is performed (the combustion fan is rotated to discharge exhaust gas from the combustion chamber before combustion of the burner is initiated).
  • the detected air-flow rate ⁇ P of the air-flow rate sensor 16 is compared with the reference air-flow rate (B mmAq) for the pre-purge constant speed.
  • a check is performed to determine whether or not a "1" is set for the no-air-movement flag.
  • a "1" is set for the no-air-movement flag, it means that in the no-air-movement, stable condition the air flow rate has become insufficient. In such a case, therefore, it is ascertained that, because there is deterioration of ventilation due to a blockage, an appliance abnormality has occurred or the lifetime of the appliance has expired.
  • a "1" is set for the abnormality/lifetime determination flag, and an abnormality/lifetime signal is output.
  • the detected air-flow rate is equal to or larger than the reference air-flow rate, the air-flow rate is not insufficient. If, at step 309, a zero is set for the no-air-movement flag, it is ascertained that the air-flow rate insufficiency is caused by wind condition. In both of the above cases, it is assumed that neither indicate the occurrence of an abnormality or the expiration of the lifetime of the appliance, which is caused by the deterioration of the ventilation due to a blockage. The combustion operation at step 106 and the following steps is begun.
  • the wind condition is determined before the combustion fan 3 is rotated, and the occurrence of an abnormality or the expiration of the lifetime of the appliance is determined by using the pre-purge fan rotation before combustion at the burner 2 is begun.
  • the determination of whether an abnormality or the expiration of the lifetime has occurred can be quickly performed in a short period of time.
  • the wind condition is determined while the combustion fan 3 is not revolving, the accuracy for the determination of the condition can be drastically increased.
  • Fig. 11 is a flowchart showing a fourth operation according to this embodiment.
  • the feature of the fourth operation is that, when the air-flow rate insufficiency that can not be resolved by increasing the revolution rate of the combustion fan is detected during combustion, an occurrence of an abnormality or the expiration of the lifetime of the appliance is performed without halting the combustion operation. Then, a determination of wind condition or no wind condition and a determination of abnormality or lifetime expiration are performed during the combustion operation.
  • the same step numbers as are used in the flowchart in Fig. 8 for the second operation are also used to denote the processes in the flowchart in Fig. 11, and no explanation for these process will be given or only a brief explanation will be given.
  • step 401 when an operation switch is turned on, at step 401, a zero is set for the abnormality/lifetime determination flag, and the initial values for the maximum momentary air-flow rate ⁇ P MAX and the minimum momentary air-flow rate ⁇ P MIN , both of which are detected by the air flow sensor 16, are input and stored. Then, the combustion operation is begun by performing the processing at step 102 and the following steps.
  • the processing at steps 102 through 121 is the same as those at steps 102 through 121 in Fig. 8 for the second embodiment and in Figs. 6 and 7 for the first operation.
  • a check is performed to determine whether the revolution rate for the combustion fan 3 is equal to or greater than the rated maximum revolution rate.
  • the revolution rate of the combustion fan 3 is less than the rated maximum revolution rate, at step 120 the fan revolution rate is increased. If the fan revolution rate is equal to or greater than the rated maximum revolution rate, it is assumed that the air-flow rate can not be raised and is insufficient.
  • a check is performed to determine whether or not a zero is held by the abnormality/lifetime determination flag.
  • the air-flow rate detected by the air-flow rate sensor 16 is employed to establish the maximum momentary value ⁇ P MAX and the minimum momentary value ⁇ P MIN .
  • a difference between the maximum momentary value ⁇ P MAX and the minimum momentary value ⁇ P MIN is compared with the limit set for the permissible range D. More specifically, the fluctuation range for the air-flow rate, which is detected by the air flow sensor 16 when the combustion fan is revolving at a specified revolution rate, is compared with the limit set for the permissible range D. When the fluctuation range of the detected air-flow rate is below the permissible range, it is assumed that there is no wind condition. In the other cases, it is assumed that there is some wind condition.
  • the air-flow rate ⁇ P detected by the air-flow rate sensor 16 is compared with the reference air-flow rate B mmaq. If the detected air-flow rate ⁇ P is smaller than the reference air-flow rate B mmAq, it means that the air-flow rate is insufficient, even though there is no wind condition, and it is assumed that an abnormality has occurred or that the lifetime has expired because of deterioration of the appliance due to blockage.
  • a "1" is set for the abnormality/lifetime determination flag, and an abnormality/lifetime signal is output. The processing for steps 127 through 130 in Fig. 7 is performed, and while combustion is continued, the combustion capability of the appliance is reduced.
  • the fourth operation the combustion operation is continued, while it is determined whether an abnormality or the expiration of the lifetime has occurred. Therefore, a situation does not occur where, during use, the supply of hot water is temporarily halted. The determination of whether an abnormality or the expiration of the lifetime of an appliance has occurred can be performed while the supply of hot water continues without interruption.
  • whether an abnormality or the expiration of the lifetime has occurred can be determined based on an air-flow rate detected by an air flow sensor for controlling the air-flow rate. Therefore, whether an abnormality or the expiration of the lifetime of an appliance has occurred can be precisely announced in consonance with the result of determination. As a result, it is possible to avoid a situation where when an appliance in which an abnormality has occurred or whose lifetime has expired, improperly continues to be used for combustion, which results in the excessive generation of CO gas. And also it is possible to avoid the unnecessary disposal of an appliance due to the determination that an abnormality has occurred in the appliance or that its lifetime has expired even though the appliance can still provide a satisfactory combustion function.
  • the determination of whether an abnormality or the expiration of the lifetime of an appliance has occurred is performed under the stable conditions with no wind condition.
  • the determination can therefore be performed without being affected by wind condition (fluctuation of the air flow sensor output due to the wind condition), such as a head wind, in the environment surrounding the installed appliance. Whether an abnormality or the expiration of the lifetime has occurred can be determined more accurately, and accordingly, the reliability of such a determination can be drastically increased.
  • a C minute period is provided at step 125 in Fig. 7.
  • the detected air-flow rate ⁇ P exceeds the reference air-flow rate even once during this period, it is assumed that in an appliance there is no abnormality and that its lifetime has not expired.
  • all of the air-flow rates detected during the C minute period are less than the reference air-flow rate, it is assumed that an abnormality has occurred or that the lifetime has expired.
  • determination for an abnormality or expiration of lifetime may be performed based on the air-flow rate, which is detected after it has been determined there is no wind condition.
  • the second through the fourth operations when the air-flow rate detected after it has been determined the condition is stable with no wind condition is lower than the reference air-flow rate, it is immediately assumed that an appliance abnormality has occurred or that the lifetime of the appliance has expired.
  • the specified C minute period may be provided, and if the detected air-flow rate exceeds the reference air-flow rate even once during this period, it is assumed that there is no appliance abnormality has occurred or that the lifetime of the appliance has not yet expired.
  • all the detected air-flow rates detected differential pressure values
  • reference differential pressure value reference differential pressure value
  • a sensor for determining an occurrence of an abnormality or the expiration of the lifetime need not be provided separately. Since an air-flow rate sensor for controlling an air-flow rate can be employed for such determination, the structure of a combustion appliance, including a function for determining whether an abnormality or the expiration of the lifetime has occurred, is simplified, and accordingly, the manufacturing cost of the appliance can be reduced.
  • the capability of a burner can be switched at multiple stages.
  • the abnormality/lifetime determiner outputs an abnormality/lifetime signal to reduce the combustion capability and a data absent portion occurs in the control characteristic data
  • capability adjustment means forcibly selects the control characteristic data on the lower side.
  • the air-flow rate detected by the air-flow rate sensor at a constant fan revolution rate is monitored.
  • the rotation of fan may be controlled so as to maintain a constant air-flow rate, and its revolution rate may be monitored.
  • a second embodiment of the present invention will now be described.
  • the schematic description for the second embodiment is as follows.
  • the features of the second embodiment are that the relationship between an air-flow rate and a fan revolution rate is monitored; that when there is an abnormality, an input down operation is performed; and that when the degree of the abnormality for the relationship is large, it is assumed that an abnormality has occurred in a combustion appliance or that its lifetime has expired and the operation is halted.
  • a first reference value and a second reference value are stored in advance. When a fan revolution rate for maintaining a predetermined air-flow rate exceeds the first reference value, fuel to be supplied to the burner is forcibly reduced. When the fan revolution rate exceeds the second reference value, supply of fuel is inhibited.
  • the determination of an occurrence of an abnormality or the expiration of a lifetime is performed by monitoring the revolution rate of a combustion fan while maintaining a constant output by an air flow sensor.
  • such a determination is performed by ascertaining whether or not the output by an air flow sensor is reduced when a constant revolution rate of the combustion fan is maintained. It is obvious that technically the same result is obtained in both cases.
  • an occurrence of an abnormality or the expiration of a lifetime is referred to simply as “the expiration of the lifetime.”
  • a sensor output target value by an air-flow rate sensor is decided in consonance with a required combustion capability that is calculated for each value output.
  • the rotation of the combustion fan is controlled so that the output of the air-flow rate matches the sensor output target value.
  • a fluctuation range for fan revolution rate data is calculated according to a stored data effectiveness determiner, if it is has been incorporated.
  • the fluctuation range exceeds a fluctuation range set in advance, it is assumed that a wind is blowing in the environment in which the appliance is installed and causes fluctuation of the data.
  • the data that are fetched are regarded as invalid data and are erased, and new data are fetched and stored.
  • the revolution rate data for the combustion fan are detected in a stable condition, when there is no wind condition, and stored.
  • a lifetime determiner calculates the average of the revolution rates for the combustion fan monitored by the fan revolution monitor, and compares the average for the fan revolution rates with input down data and lifetime determination data for each sensor output target value.
  • L 1 or more sets of data are entered in an area between input data and lifetime determination data, a down command for combustion capability is output. If, from among the fan revolution rate averages for the individual sensor output target values, the values of L 2 or more sets of data exceed those of the lifetime determination data, it is assumed that the lifetime of an appliance has expired and a lifetime signal is output.
  • L 1 and L 2 are reference data set counts that are provided in advance.
  • the combustion capability is reduced. Even if the air-flow rate is lowered, the combustion is performed while a preferable combustion function is maintained within the reduced air-flow rate range.
  • a lifetime signal is output by the lifetime determiner, it is assumed that the appliance has been locked by halting combustion. Combustion performed at an insufficient air-flow rate can be prevented so as to avoid the dangers associated with the increases in the amount of carbon monoxide, etc., that are generated.
  • Fig. 17 is a block diagram illustrating the structure of lifetime determination means, which is the characteristic component of the embodiment.
  • the inherent lifetime determination means includes a combustion controller 1017, a fan rotation controller 1018, and a diagnostic mode operation unit 1021 for operating in an appliance lifetime diagnostic mode.
  • the structures and the operations of the combustion controller 1017 and the fan rotation controller 1018 are the same as were previously described, and no explanation for them will be given.
  • the diagnostic mode operation unit 1021 includes a target value designator 1022, a fan rotation command unit 1023, a fan rotation monitor 1024, a lifetime determiner 1027, and a timer 1031.
  • the processing by the diagnostic mode operation unit 1021 is performed when there is no combustion at a burner 2.
  • the operation in the diagnostic mode is performed when the revolution rate of a combustion fan 3 during combustion has exceeded the upper limiter of the fan control characteristic data shown in Fig. 16 and combustion is thus halted.
  • the limiter value is acquired from a boundary point at which the carbon monoxide, hydrocarbon, and nitrogen oxide contents of exhaust gas are increased due to incomplete combustion.
  • the target value designator 1022 designates one or more sensor output target values of an air-flow rate sensor 16 to perform lifetime diagnosis.
  • sensor output target values to be designated may be input and stored in advance in memory, or the target values may be input externally by means of a keyboard or by using a memory card.
  • the sensor output target values V S1 through V SN selected by the target value designator 1022 are transmitted to the fan rotation command unit 1023.
  • the fan rotation command unit 1023 collectively or sequentially transmits the sensor output target values V S1 through V SN to the fan rotation controller 18 within a predetermined period of time.
  • the fan rotation controller 1018 Upon the receipt of the sensor output target value V S1 from the fan rotation command unit 1023, for example, the fan rotation controller 1018 so controls the rotation of the combustion fan 3 that the output of the air-flow rate sensor 16 equals the sensor output target value V S1 .
  • the fan rotation controller 1018 so controls the rotation of the combustion fan 3 that the output of the air-flow rate sensor 16 equals the value V S2 . In this manner, relative to the individual sensor output values V S1 through V SN from the fan rotation command unit 1023, at respective predetermined time intervals rotation of the combustion fan 3 for the different sensor output target values is performed.
  • the fan rotation monitor 1024 fetches one or more values for the revolution rate of the combustion fan 3 for each of the sensor output target values V S1 through V SN , and stores them in a memory.
  • the timer 1031 is employed to store these fan revolution rates.
  • the fan rotation monitor 1024 sequentially fetches the fan revolution rates R 1 through R M at intervals of T seconds, and stores them in the memory.
  • the effectiveness determiner 1025 calculates, as a fluctuation range, a difference between the maximum revolution rate and the minimum revolution rate among the stored fan revolution rates R 1 through R M , and determines whether or not the acquired fluctuation range is within a fluctuation range that is set in advance.
  • the effectiveness determiner 1025 instructs the repeated erasure of the stored data, and again detects and stores fan revolution rates.
  • the fluctuation range of the fan revolution rate data falls within the set range, the detection and storage of the fan revolution rate for the next sensor output target value is instructed, and the fan revolution rate data for each sensor output target value are detected and stored under stable conditions while there is no wind condition.
  • the effectiveness determiner 1025 compares the fluctuation range of the values detected by the air-flow rate sensor 16 with a set fluctuation range (the set fluctuation range is defined by an upper limit level and a lower limit level, but may be defined by only an upper limit level). When the variance exceeds the set fluctuation range (when the variance exceeds the upper limit level if the set fluctuation range is provided only by the upper limit level), it is assumed that there is some wind condition. If the variance for the values (sensor output) detected by the air-flow rate sensor 16 falls within the set fluctuation range, it is assumed that the condition is stable and there is no wind condition.
  • Data shown in Fig. 18 are provided in advance for the lifetime determiner 1027. More specifically, relative to the fan control characteristic data RI at the initial time when a water heater having no deterioration due to ventilation blockage is installed, input down data RB is provided on the side where the fan revolution rate is large at the same sensor output target value. Further, relative to the input down data, lifetime determination data RC is provided on the side where the fan revolution rate is large at the same sensor output target value. The input down data RB is a first reference value and the lifetime determination data RC is a second reference value. As is shown in Fig. 19, the lifetime determiner 1027 calculates the average values RA 1 through RA N for fan revolution rate data that are detected and stored for each of the sensor output target values V S1 through V SN . The average values RA 1 through RA N of the fan revolution rates for each sensor output target value are compared with the data shown in Fig. 18.
  • a check is performed to determine whether the number of average values dropped in an area between the input down data RB line and the lifetime determination data RC line is equal to or greater than preset number L 1 (L 1 is an integer of 1 or greater).
  • L 1 is an integer of 1 or greater.
  • a predetermined value is provided for the amount of a reduction in the combustion capability, and as a down command is issued for each reduction of the combustion capability, the combustion capability is reduced step by step.
  • the amount of the combustion capability reduction is in proportion to the number of fan revolution rate average values that present in the area between the input down data RB and the lifetime determination data RC.
  • the lifetime determiner 1027 counts fan revolution average values RA 1 to RA N , for each sensor output target value V S1 to V SN , that exceed lifetime determination data (lifetime determination data RC line).
  • L 2 is an integer of 1 or greater
  • L 2 is an integer of 1 or greater
  • a report unit 1030 receives signals concerning the results of determinations obtained by the lifetime determiner 1027, and communicates the determination results.
  • the determination results obtained by the lifetime determiner 1027 are communicated by employing appropriate methods, such as the use of characters and symbols to display the results on a liquid crystal screen or the turning on a lamp or the blinking of a lamp, and the sounding of a buzzer to communicate the result of a lifetime determination.
  • Fig. 20 at step 1101, combustion for heating water is being performed.
  • the combustion controller 1017 supplies to the proportional control valve 14 a valve opening drive current in consonance with a required combustion caloric value.
  • the sensor output target value for the air-flow rate sensor 16 in consonant with the required combustion caloric value is determined.
  • a voltage to be applied to the combustion fan 3 is controlled so that the output of the air-flow rate sensor 16 equals the sensor output target value, and the rotation of the combustion fan 3 is controlled.
  • the fan revolution rate is detected.
  • a check is performed to determine whether or not the detected revolution rate for the combustion fan 3 has reached the upper limiter for the fan control characteristic data shown in Fig. 16. When the fan revolution rate has not yet reached the upper limiter, it is assumed that the combustion operation is being performed at the normal air-flow rate, and the combustion operation is continued. If the fan revolution rate advances beyond the upper limiter, at step 1106 combustion is immediately halted, and program control is shifted to perform the lifetime diagnostic mode operations shown in Fig. 21.
  • the sensor output target values V S1 through V SN are set.
  • rotation of the combustion fan 3 is begun.
  • the fan revolution rate is so controlled that the output of the air-flow rate sensor 16 equals the first sensor output target value V S1 .
  • the timer 1031 which has been reset is turned on.
  • the fan revolution rate sensor 28 detects the revolution rate R 1 for the combustion fan 3, and stores it in the memory.
  • the detection and storing of the revolution rate for the combustion fan 3 is repeated each T seconds, and M (an integer of 1 or greater) sets of detected fan revolution rate data, R 1 through R M , are stored in the memory.
  • step 1207 from among the stored fan revolution rate data R 1 through R M , a difference between the maximum data value and the minimum data value is calculated to provide a fluctuation range value.
  • a check is performed to determine whether or not the fluctuation range value is smaller than the fluctuation range value e that is set in advance.
  • M sets of fan revolution rate data R 1 through R M which are stored in the memory for the sensor output target value V S1 , are erased.
  • the sensor output target value V S1 is again designated, and the processing for detecting and storing the fan revolution rates at steps 1202 and the following steps is performed.
  • step 1207 again, a check is performed to determine whether or not the fluctuation range value for the data detected and stored is smaller than the set fluctuation range value e. If the fluctuation range value is outside the fluctuation range e, the detection and storing of the fan revolution rates at the sensor output target value is repeated.
  • the average value RA 1 is calculated for the data R 1 through R M that have been detected and stored.
  • a check is performed to determine whether or not the number N for the fan revolution rate average values equals N, which is the number of the sensor output target values V S1 through V SN .
  • N 1 when the average RA 1 of the fan revolution rates at the sensor output target value V S1 is acquired.
  • N 2 when the average RA 1 of the fan revolution rates at the sensor output target value V S1 is acquired.
  • the sensor output target value V S2 is selected, and the rotation of the combustion fan 3 is so controlled that the output value of the air-flow rate sensor 16 is V S2 .
  • the fan revolution rates R 1 through R M are detected at the sensor output target value V S2 and stored. Further, the fan revolution rate data are acquired and stored while there is no wind condition and while the fluctuation range value does not exceed the fluctuation range value e.
  • the average value RA 2 for the data R 1 through R M is acquired.
  • the determination of the expiration of the lifetime is performed.
  • the average fan revolution rates RA 1 through RA N which are acquired for the corresponding sensor output target values V S1 through V SN , as is shown in Fig. 19, are compared with the input down data RB and the lifetime determination data RC in Fig. 18.
  • RA 1 is compared with the input down data RB 1 and lifetime determination data RC 1 .
  • the average value RA 2 for the fan revolution rates at the sensor output target value V S2 is compared with the input down data RB 2 and the lifetime determination data RC 2 .
  • the average values RA 1 through RA N are compared with the input down data RB 1 through RB N and lifetime determination data RC 1 through RC N for the corresponding sensor output target values.
  • the average fan revolution rates located in an area between the input down data RB line and the lifetime determination data RC line are counted. If the count of the average values located in that area is equal to or greater than reference number L 1 , which is provided in advance, a combustion capability down command signal is output.
  • L 1 a reference number provided in advance
  • L 2 a reference number provided in advance
  • more average fan revolution rates are present in an area above the lifetime determination data RC line, it is assumed that the lifetime of the appliance has expired, and a lifetime signal is output.
  • the combustion capability is reduced, the volume of the gas being supplied is reduced to avoid the inadequate supply of air, and the next combustion operation is enabled.
  • the appliance is locked in the combustion stop state, i.e., combustion is not enabled, so that combustion is prevented while deterioration of the appliance occurs due to the obstruction of ventilation.
  • the results obtained through the lifetime determination operation are identified and reported by the report unit 1030.
  • a combustion capability down command signal is output to reduce the combustion capability. Therefore, the combustion operation can be continued while the air supply inadequacy is resolved. Since the degradation of the combustion is resolved, so that the water heater can be used until it is replaced by a new one, this is very convenient.
  • the lifetime diagnosis operation is performed more reliably.
  • the air flow resistance along an air path (air passage) that runs from the combustion fan 3 to an exhaust path 29 is different when there is combustion at the burner 2 and when combustion is halted.
  • the air flow resistance when there is combustion at the burner is increased and is greater than that when combustion is halted.
  • the increase in the air flow resistance varies depending on the caloric combustion value.
  • the lifetime determination can be performed more accurately and reliably.
  • a plurality of sensor output target values have been designated in the above embodiment, only one sensor output target value may be selected.
  • a plurality of fan revolution rates R 1 through R M are detected for each sensor output target value in this embodiment, detection of only one fan revolution rate may be performed. In such a case, calculations to produce average values are eliminated, and in this invention the detected data is the equivalent of an average value. In other words, the detection of the fan revolution rate is equivalent to the operation for calculating the average value of the fan revolution rates.
  • the determination processing can be performed in a short time. However, if a plurality of the sensor output target values are designated and a plurality of fan revolution rates are detected, as in this embodiment, the determination of the lifetime can be performed more accurately.
  • the combustion is immediately halted and the operation is shifted to the lifetime diagnosis processing.
  • a lifetime diagnosis instruction flag may be set, and the lifetime diagnosis may be performed at an appropriate occasion, such as when the appliance is not being used after combustion has been halted, or before combustion is next initiated.
  • combustion is not halted, even though the fan revolution rate exceeds the upper limiter, and the appliance can be continuously used. A user does not experience any inconvenience when using the appliance, and its usability is improved. In this case, the following processing may be performed.
  • the degree of safety is determined in consonance with how much the fan revolution rate exceeds the upper limiter. In the most critical condition, combustion is immediately halted to perform lifetime diagnosis. In a less (lower) critical condition, combustion is continued and the lifetime diagnosis is performed at an appropriate time after the use of the appliance is ended.
  • the upper limiter for the fan control characteristic data provided to prevent the runaway of the combustion fan 3 has been employed as an upper limiter for a fan revolution rate that serves as a reference for lifetime diagnosis.
  • a special upper limiter for lifetime diagnosis is set separately from the upper limiter for runaway prevention, and when the fan revolution rate exceeds the special upper limiter for lifetime diagnosis, the lifetime diagnosis may be performed in the above described manner.
  • the combustion fan has been so rotated as to maintain the target value for an air-flow rate, and the revolution rate has been monitored.
  • a method whereby an air-flow rate detected by the air-flow rate sensor is monitored while a constant revolution rate for the combustion fan is maintained can provide the same result.
  • the input down data is the first reference air-flow rate that is lower than an appropriate air-flow rate
  • the lifetime determination data is a second reference air-flow rate that is lower than the first reference air-flow rate.
  • an air-flow rate when a combustion fan is rotated at a constant revolution rate during is no wind condition is stored as an initial value.
  • the air-flow rate is measured under the same conditions. The obtained air-flow is compared with the stored air initial flow rate to perform lifetime determination.
  • a plurality of outputs by an air-flow rate sensor 16 are obtained at a time that a combustion fan is not being rotated, such as at the time of shipping of a combustion appliance or at a time when there is no combustion at a burner after its installation.
  • a condition determiner ascertains that there is no wind condition.
  • the initial sensor value for such conditions is established and stored in the memory.
  • a combustion fan is rotated under set reference conditions and without combustion being initiated at a burner.
  • the condition determiner ascertains the conditions are stable and there is no wind condition
  • the output of the air-flow rate sensor is fetched. Based on the detected data, an initial value is established that serves as a reference for determining whether there is degradation of ventilation, and is stored in the memory.
  • the output of the air-flow rate sensor detected at the time there is no combustion at a burner and no rotation of a combustion fan, is employed to determine the wind condition.
  • a fluctuation of the sensor output value relative to the initial value is calculated. If the fluctuation value exceeds a reference value provided in advance to determine the condition of the sensor, it is assumed that the sensor is faulty, and a determination signal is output.
  • the combustion fan is rotated, with no combustion at the burner, under the same reference conditions as when the initial value was established.
  • the output of an air supply volume sensor under the stable conditions, with no wind condition, is fetched as maintenance data.
  • the fluctuation of the maintenance data relative to the initial value, or the value for fluctuation between the maintenance data fetched at the current interval and the maintenance data fetched at the preceding interval, is obtained.
  • a signal is output warning that the deterioration of ventilation due to a blockage has occurred.
  • the driving requirement for the combustion fan is detected. If the detected driving requirement exceeds the upper limit of a control range, a signal warning of the expiration of the lifetime of the appliance is output, a danger notice is displayed on an appropriate display means, and the combustion operation is forcibly halted.
  • Fig. 22 is shown the characteristic structure of this embodiment wherein provided are a sampling unit 2025, a condition determiner 2026, an initial value establishing unit 2027, a memory 2028, a fan driver 1019, a sensor fault determiner 2030, a lifetime determiner 2031, a ventilation deterioration determiner 2032, an input down controller 2033, display means 2034, and a timing mechanism 2035. These components function in consonance with a sequence program stored in the memory of a controller 15.
  • the sampling unit 2025 fetches the output of an air-flow rate sensor 16 by using the timing mechanism 2035, such as a timer, each time the appliance is powered and each time a predetermined time interval, such as one day, one week, or one month, provided in advance, has elapsed since the power-ON time.
  • the output is transmitted as needed to the condition determiner 2026, the initial value establishing unit 2027, the input down controller 2033 and the ventilation deterioration determiner 1032.
  • the permissible range e for the fluctuation in the outputs of the air-flow rate sensor 16 during is no wind condition is provided in advance for the condition determiner 2026.
  • the permissible range e for the fluctuation in the outputs of the air-flow rate sensor 16 during is no wind condition is provided in advance for the condition determiner 2026.
  • an environmental situation where a water heater is installed outdoors, wind flows into the appliance and causes the output of the air-flow rate sensor 16 to fluctuate even though the combustion fan 3 is halted.
  • a time when there is no change in the output of the air-flow rate sensor 16, i.e., when there is no wind condition, is detected and the output of the air-flow rate sensor 16 is employed as effective data.
  • the condition determiner 2026 fetches a plurality of the outputs by the air-flow rate sensor 16 at predetermined time intervals (for example, 10 sets of data at 0.1 second interval). If the variation in the readings for the plurality of data sets, i.e., a difference between the maximum value and the minimum value of data that are fetched, is within the permissible range e, the condition determiner 2026 ascertains that the condition is stable with no wind condition. If a difference between the maximum value and the minimum value of data that are fetched exceeds the permissible range e, the condition determiner 2026 ascertains a condition with some wind condition. The results of the determination are transmitted to the initial value establishing unit 2027 and the ventilation deterioration determiner 2032. In this case, only a result obtained when there is no wind condition may be transmitted to the initial value establishing unit 2027 and the ventilation deterioration determiner 2032.
  • predetermined time intervals for example, 10 sets of data at 0.1 second interval.
  • the initial value establishing unit 2027 designates the output of the air-flow rate sensor 16 at that time as a initial sensor value, and stores it in the non-volatile memory 2028.
  • the minimum value or the average value of a plurality of sets of fetched data is regarded as an initial value.
  • the combustion fan 3 is rotated under the standard set condition with no combustion at the burner 2, i.e., at the maximum fan revolution rage in the control range for this embodiment.
  • a plurality of outputs by the air-flow rate sensor 16 are fetched through the sampling unit 2025 at a specified sampling timing set in advance. It is confirmed that, based on the fetched data, the condition determiner 2026 has ascertained the condition is stable with no wind condition.
  • the initial value for sensor output at the maximum revolution rate for the combustion fan 3 is established as a reference value for determining the deterioration of ventilation, and is stored in the memory 2028.
  • the fan driver 2029 receives, from the establishing unit 2027, an instruction to rotate the combustion fan 3 at the maximum revolution rate, and rotates the combustion fan 3 in accordance with the instruction. Besides an instruction from the initial value establishing unit 2027, the fan driver 2029 receives a fan drive instruction from the ventilation deterioration determiner 2032, and rotates the combustion fan 3 at the maximum revolution rate within a control range.
  • the ventilation deterioration determiner 2032 fetches the output of the air-flow rate sensor 16 at predetermined time intervals.
  • an instruction is transmitted to the fan drive 1019 to rotate the combustion fan 3 at the maximum revolution rate, as the basis for the setting standards requirement.
  • the ventilation deterioration determiner 2032 fetches the output of the air-flow rate sensor 16 through the sampling unit 2025 at predetermined sampling times.
  • the fluctuation of the output of the air-flow rate sensor 16, relative to the initial value for determining the deterioration of ventilation, is calculated.
  • an absolute value for a difference between the initial value and maintenance data value is calculated as the fluctuation value. This fluctuation value is compared with the reference value provided in advance.
  • the deterioration of the ventilation in the appliance may be caused by soot that blocks the heater water 4, or by the deposit of dust in an air inlet (not shown), on a curved portion of blades of the combustion fan 3, or in a hole punched in metal (not shown).
  • the deterioration of ventilation may also be caused by the attachment of dust to the burner 2.
  • the lifetime determiner 2031 Upon receipt of the signal from the ventilation deterioration determiner 2032 warning that there is deterioration of ventilation, the lifetime determiner 2031 detects the revolution rate for the combustion fan 3 while combustion is taking place at the burner 2, and determines whether or not it exceeds the maximum revolution rate, which is the upper limit for the control range. When the revolution rate exceeds the upper limit for the control range, it is assumed that ventilation in the appliance is blocked and an air volume required for combustion can not be supplied. A danger warning signal is output, and combustion at the burner of the water heater is immediately halted. A function that hereinafter does not accept a combustion instruction is performed to disable the following combustion operation of the appliance.
  • the input down controller 2033 calculates a ratio for maintenance data value fetched at periodic intervals to the initial value.
  • a ratio for maintenance data value fetched at periodic intervals is smaller than a reference ratio provided in advance, it is assumed that ventilation is considerably deteriorated due to blockage with soot, even though the lifetime has not yet expired.
  • the valve opening current to the proportional control valve 14 is controlled to restrict the degree of opening of the valve 14, and the fuel to be supplied to the burner 2 is reduced.
  • the sensor fault determiner 2030 compares, at intervals, the output of the air flow sensor 16 which when no wind condition with the initial sensor value when no wind condition, while combustion at the burner 2 is not performed and the combustion fan 3 is not rotated. In other words, the fluctuation of the sensor output relative to the initial value is acquired. When the fluctuation value exceeds the sensor reference value provided in advance, it is assumed that a sensor fault has occurred, and a sensor fault signal is output.
  • the display means 2034 receives a ventilation deterioration warning signal from the ventilation deterioration determiner 2032, a danger warning signal for reporting the status of the lifetime of the appliance from the lifetime determiner 2031, and a sensor fault signal from the sensor fault determiner 2030, and then displays these signals on a display device for a remote controller, for example.
  • Various display methods can be employed by the display means 2034: symbols, etc., having a variety of forms, for example, are displayed on a liquid crystal screen; a lamp ON/OFF or blinking state that is varied for visual notification; a changed volume of buzzer, a continuous sound, an intermittent sound, or the length of an intermittent sound.
  • a signal from a fan rotation sensor 28 is used to determine whether the combustion fan 3 is not revolving or is revolving at the maximum revolution rate.
  • a signal from a flame rod 20 is employed to determine whether or not combustion is taking place at the burner 2.
  • Fig. 23 is shown the processing performed by the initial value establishing unit 2027 for establishing the initial sensor output value when no wind condition, and the initial value for determining ventilation deterioration.
  • This processing is performed at an appropriate time, such as when an appliance is powered on for an inspection after it is manufactured, when the appliance is installed and powered on, or when a command for the operation is issued by use of a command button to initiate an initial value establishment mode.
  • step 2101 a check is performed to determine whether or not there is combustion at the burner 2. This checking is performed by detecting a signal from the flame rod 20. When there is no combustion at the burner 2, at step 2102 it is confirmed that the combustion fan 3 is halted.
  • the output of the air-flow rate sensor 16 is read.
  • a check is performed to determine whether or not the reading of the sensor output has been terminated, i.e., whether or not T minutes has elapsed.
  • the reading of the sensor output is performed, for example, one value each 0.1 second.
  • a check is performed to determine whether or not T minutes have elapsed during which a predetermined number, such as five or ten, of sensor outputs have been read.
  • a calculation is performed to obtain the difference between the maximum value (MAX) and the minimum value (MIN) of the sensor outputs that were read.
  • a check is then performed to determine whether or not the difference is disposed between the maximum value and the minimum value, i.e., the fluctuation of the fetched sensor outputs lies within the permissible range e 1 (e in Fig. 4 e 1 ). If the fluctuation value is not within the permissible range, it is assumed that there is some wind condition. Since data, even if acquired, are affected by wind condition and can not serve as effective data, no data is fetched, and after a wait of 24 hours, the processing at step 2101 and the following steps are again performed.
  • V MIN (0) is one of the initial sensor values obtained when no wind condition.
  • the combustion fan 3 is rotated at the maximum revolution rate (3000 rpm in the embodiment) in the control range.
  • the output of the air-flow rate sensor 16 is read.
  • a plurality of sensor output values are read, and at step 2109, a check is performed to determine whether or not the time for the reading has elapsed.
  • the time for the reading has elapsed
  • the fluctuation does not lie within the range e 2 , it is assumed that data vary and that fluctuation occurs because there is some wind condition. No data are fetched, and after waiting 24 hours, the processing at step 2101 and the following steps is repeated.
  • a check is performed to determine whether or not m equals three.
  • m is incremented by one (in this embodiment m is increased from zero to one).
  • the operation is halted until one week has elapsed. Then, the processing at step 2102 and the following steps is performed.
  • the four initial sensor values V MIN (0) through V MIN (3), obtained while there is no wind condition, and the four initial values V MAX (0) through V MAX (3), for determining ventilation deterioration, are stored until m equals three.
  • the average of the four values V MIN (0) through V MIN (3) is calculated to establish the initial sensor value V MIN for a condition whether there is no wind condition.
  • the average of the four V MAX (0) through V MAX (4) is calculated to establish the initial value V MAX for determining whether there is ventilation deterioration when the combustion fan is being rotated at the maximum revolution rate.
  • the established initial values V MIN and V MAX are stored in the memory 2028.
  • the processing at steps 2100 through 2113 establishes the initial sensor value V MIN , while no wind condition and no fan rotation immediately after the water heater is installed and when the ventilation in the water heater is not blocked; and the initial value V MAX , a reference for determining whether there has been ventilation deterioration, while the combustion fan is rotated at the maximum revolution rate and ventilation is not blocked. These initial values are stored thereafter.
  • Fig. 24 is a flowchart for the processing whereby, after the initial value V MAX and the initial sensor value V MIN obtained during no wind condition have been established and stored, the deterioration of ventilation and the expiration of the lifetime of the appliance are determined at periodic intervals, e.g., every L combustion times or every M months.
  • the process at steps 2101 through 2111 in the flowchart in Fig. 23 is performed.
  • the fluctuation value is compared with the sensor reference value that is provided in advance, i.e., permissible range for the air-flow rate sensor 16 in this embodiment, to determine whether or not the fluctuation value is within the permissible range.
  • the limits of the fluctuation lie outside the permissible range, at step 2209 it is ascertained that an air-flow rate sensor 16 is faulty.
  • a sensor fault signal is then output by the sensor fault determiner 2030, and is displayed by the display means 2034.
  • the limits of the fluctuation lie within the permissible range, it is ascertained that the air-flow rate sensor 16 is operating normally, and program control moves to step 2203.
  • the input down controller 2033 calculates a ratio for the value V MAX (N) to the initial value V MAX .
  • a check is performed to determine whether or not the ratio is smaller than the reference ratio set in advance.
  • the reference ratio is set by using the graph data shown in Fig. 25.
  • V A1 represents the output of the air-flow rate sensor 16 when the revolution rate for the combustion fan 3 is changed when no combustion.
  • Data V A1 is obtained at A 1 , where the air flow passage area in the appliance is not blocked at all.
  • the relationship between the revolution rates and sensor outputs obtained when the blockage rate is changed at a plurality of stages, for example, 90%, 60%, 50% and 30%, is also separately calculated.
  • the data V A1 is obtained immediately after the appliance is manufactured and when there is absolutely no blockage of ventilation.
  • Graph data V A2 represents the output of the air-flow rate sensor 16, immediately after the appliance was manufactured when there is combustion at the burner 2 and the fan revolution rate is changed, and when there is no ventilation blockage. Generally, compared with a period when there is no combustion, air flow resistance is increased when there is combustion. Thus, with respect to the normal output V A1 at the time there is no combustion, the data of the fan revolution rate and the sensor output at the time there is no combustion and the passage area is reduced by Y % to the passage area A 2 , is equivalent to the data for V A2 .
  • the passage area A 2 at that time is also acquired as a well known value.
  • the graph data V A2 is obtained by calculation of graph data V A1 .
  • the data V A2 may be acquired when combustion is actually performed.
  • Graph data V A4 represents the output of the air-flow rate sensor 16 under abnormal combustion conditions. Assuming that the blockage rate is changed to W% from the output V A2 provided during normal combustion due to the deterioration by ventilation blockage, the data V A4 is acquired from the data V A1 or V A2 by calculation. It should be noted that W% is calculated based on a case wherein the content of carbon monoxide in the exhaust exceeds a specified amount.
  • Data V A3 represents the sensor output at an abnormal occasion when deterioration due to the blockage of ventilation has occurred.
  • the air flow passage area for the graph data V A1 is assumed to be A 1
  • the blockage rate relative to the passage area A 1 differs for V A2 , V A3 and V A4 .
  • the passage area for the graph data V A2 is A 2
  • the passage area for the graph data V A3 is A 3
  • the passage area for the graph data V A4 is A 4 .
  • the ratio V A3 /V A1 calculated for the abnormal sensor output V A3 with no combustion to the normal sensor output V A1 with no combustion is multiplied by constant K, and the result is employed as a reference rate.
  • V MAX (N) to V MAX is equal to or greater than the reference rate, a problem in deterioration due to ventilation blockage does not arise, and combustion is preferably performed.
  • combustion for the water heater is performed under normal combustion control.
  • V MAX (N) to V MAX When the ratio of V MAX (N) to V MAX is smaller than the reference rate, it is assumed that deterioration of the appliance has been caused by ventilation blockage.
  • a check is performed to determine whether or not the revolution rate for the combustion fan 3 equals the maximum value of the control range. When the combustion fan revolution rate does not equal the maximum rate, it is assumed that the air-flow rate can be increased, even though deterioration due to the ventilation blockage has occurred, and a normal combustion operation is performed.
  • the revolution rate for the combustion fan 3 equals the maximum rate (3000 rpm in this embodiment) in the control range
  • the sampling unit 2025 uses the clock mechanism 2035 to determine whether or not the succeeding predetermined interval, for example, the time represented by L for combustion periods or M months, has elapsed. When the time has elapsed, at step 2208, N is incremented by one.
  • a check is performed to determine whether or not the fan revolution rate for the combustion fan 3 has reached the maximum revolution rate (upper limit) for the control range.
  • the fan revolution rate has not yet reached the upper limit, the fan revolution rate can be increased more, and combustion, therefore, is continued.
  • the lifetime determiner 2031 outputs a signal warning showing a danger that the expiration of the lifetime may occur. As the warning is displayed by the display means 2034, and combustion at the burner 2 is forcibly halted to disable any subsequent burner combustion, a dangerous condition resulting from incomplete combustion is avoided.
  • the setting standard requirement for the combustion fan has been established based on the maximum revolution rate in the control range for the combustion fan 3.
  • the standard condition may be set based on a revolution rate that is slightly lower than the maximum revolution rate.
  • the setting standard requirement may be provided based on a drive current or the work performed by the combustion fan 3, instead of being based on the revolution rate.
  • the reference value D provided at step 2211 in the flowchart in fig. 24 may be calculated in advance and may be provided as externally input data.
  • the appliance itself may acquire the data V A1 in Fig. 25 by rotating the combustion fan 3, and may obtain the reference value D by computation and set it.
  • a value other than D (V A1 - V A3 )/2 may be employed as the reference value D.
  • the ventilation deterioration determiner 2032 calculates a fluctuation value by using an absolute value of a difference between the initial value V MAX , for determining ventilation deterioration, and the maintenance data V MAX (N).
  • the fluctuation for determining the ventilation deterioration may be acquired by using an absolute value of a difference between the maintenance data V MAX (N+1), which is fetched during the current interval, and the maintenance data V MAX (N), which is fetched during the preceding interval, i.e., by using an absolute value for the fluctuation of the maintenance data that are fetched at the two intervals (corresponding to the inclination data changes).
  • the ventilation deterioration determiner 2032 compares the fluctuation value with the reference value D and determines the extent of the deterioration due to ventilation blockage in the same manner as in the above embodiment. Thus, a case where the initial sensor value fluctuates in consonance with a transient change need not be taken into consideration.
  • the condition determiner in the above embodiment determines the wind condition by using a data variance detected by the air supply volume sensor (the air-flow rate sensor 16).
  • the revolution rate for the combustion fan 3 is controlled so as to maintain a steady output by the air-flow rate sensor.
  • a fan drive current or a work amount may be detected instead of the fan revolution rate, and the wind condition may be identified by determining whether or not a variance in the detected data lies within the permissible fluctuation range.
  • the deterioration due to ventilation blockage can be determined from the magnitude of the variation in the driving requirements, such as the fan revolution rate.
  • the driving condition such as the fan revolution rate for which the output of the air-flow rate sensor serves as a set value, when there is no deterioration due to ventilation blockage, is set as an initial value.
  • the driving condition such as a fan revolution rate for which the outputs by the air-flow rate sensor are the same, is obtained.
  • the initial sensor value when there is no wind condition, deterioration due to ventilation blockage does not occur and the combustion fan is halted, and the initial value for determining ventilation deterioration when the combustion fan is rotated under the standard requirements, are established in advance as data acquired when no combustion, and are stored.
  • the deterioration due to ventilation blockage is detected in consonance with the fluctuation relative to the initial value for the maintenance data that are fetched at predetermined intervals. Therefore, the initial value of the air-flow rate sensor whose characteristic varies for each combustion appliance is established not at shipping time, but in consonance with the environment after the appliance has been installed. Therefore, the expiration of a lifetime due to deterioration by ventilation blockage can be precisely determined.
  • the fluctuation relative to the initial sensor value during no wind condition is calculated to determine sensor faults. Since the value output by a faulty sensor is not adopted as an effective value, the determination of deterioration due to ventilation blockage and the reliability of that processing can be enhanced.
  • the air-flow rate sensor 16 during no wind condition when the output of the air-flow rate sensor 16 during no wind condition is changed from the initial value outside a permissible range, it is ascertained that the air-flow rate sensor is faulty.
  • some air-flow rate sensors can be continuously used if correcting the zero point at the initial value by adding the fluctuation value.
  • the feature of the fourth embodiment is that the zero point value, which is an output value for the air-flow rate sensor 16 when no wind condition, is detected and corrected for.
  • Fig. 26 is a detailed flowchart for detecting the zero point value.
  • zero point correction is performed when the appliance is activated while it is cool.
  • a "0" is set for the output count m for an inappropriate data signal, and a "0" is also set for the maximum output value V omax and the minimum value V omin of the air-flow rate sensor 16.
  • the value V o output by the air-flow rate sensor 16 is stored in the memory.
  • the value V o output by the air-flow rate sensor 16 stored in the memory is compared with the upper output limit value V omaxlimit at the zero point stored in the memory, and with the lower output value V ominlimit at the zero point.
  • step 3003 and 3004 if the output value V o is equal to or less than the zero point upper output limit value V omaxlimit , and is equal to or greater than the zero point lower output value V ominlimit , the value V o output by the air-flow rate sensor 16 is sequentially transmitted as stored data V o,i to the memory 30.
  • the sensor output value V o is regarded as inappropriate data and is erased from the memory.
  • the output count for an inappropriate data signal is stored in the memory.
  • the sensor output value V o,i stored in the memory for use is regarded as the maximum value V omax , and is compared with the data V o,i , which is used next. The larger value is stored in the memory as the maximum value V omax . In this manner, the maximum value V omax is selected from the sensor outputs V o,i that are sequentially used at step 3002.
  • the minimum value V omin is selected from the sensor outputs V o,i .
  • a difference between the maximum value V omax and the minimum value V omin is calculated as needed, and the difference is compared with a permissible fluctuation range e.
  • the difference is assumed that there is some external wind condition.
  • the detected data is regarded as inappropriate data, and the sensor output is read again. If the difference lies within the fluctuation range, it is assumed that there is no wind condition, and the detected data is stored in the memory as appropriate data.
  • a check is performed to determine whether or not the number of the sensor output values V o,i stored in the memory as appropriate data obtained when no wind condition, has increased until it equals a predetermined number t.
  • the sensor output values V o,i are employed as correction data.
  • the average value for the correction data is calculated, and is stored in the memory as zero point correction value V o of the air-flow rate sensor 16.
  • the average value is to be used for determining the expiration of a lifetime and for controlling an air-flow rate.
  • step 3014 count m for the detected data regarded as inappropriate data is compared with a predetermined count M.
  • m M
  • V o,i the detection of the sensor output at step 3000 and the following steps is performed.
  • the zero point correction is thereafter terminated. In this case, zero point correction process is again performed after a predetermined period of time has elapsed.
  • an error signal is output frequently, it can be assumed that the air-flow rate sensor 16 is faulty or that its lifetime has expired.
  • the zero point value is used as a new corrected zero point for the air-flow rate sensor, and program control moves to a post-fan ignition sequence to begin a normal combustion operation by using the air-flow rate sensor.
  • the present invention is not limited to the first through the fourth embodiments, and can be modified in various modes.
  • the burner 2 that has three stages for switching a combustion function has been employed, the number of stages for the combustion function of the burner 2 may be a number other than three, or a burner may be used that is not a combustion switching type.
  • a differential pressure at an interval between the upper portion and the lower portion, with the burner 2 in between, has been detected by the differential pressure sensor 16, which is an air-flow rate sensor.
  • a differential pressure need only be detected at a desirable segment in the path between the upstream and the downstream portions in the air-flow rate passage, which extends from the air supply section for the burner to an exhaust path.
  • a number of segments in the path for detecting a differential pressure can be set, such as a segment between the inlet port for a combustion fan and a combustion chamber, a segment between the outlet for the combustion fan and the combustion chamber, a segment between the air inlet or the air outlet for the combustion fan and an upper exhaust tap of a water heater, or a segment between a combustion chamber and an exhaust tap.
  • the air flow driven by the combustion fan 3 can be detected precisely by using a differential pressure.
  • the system employed for the embodiments, where the differential pressure is detected at a segment in the path between the upstream and downstream portions with the burner 2 in between, is preferable.
  • the differential pressure sensor 16 has been employed as an air-flow rate sensor.
  • various other sensors for detecting an air-flow rate directly or indirectly may be employed, such as a hot-wire anemometer or a Karman vortex anemometer, or an anemometer of a propeller rotation type for detecting an air-flow rate directly.
  • the setting condition for a combustion fan has been provided based on a fan revolution rate.
  • the setting condition for the combustion fan may be provided based on another condition, such as a drive current for the combustion fan or the amount of work performed.
  • the combustion fan is rotated in accordance with the setting condition, such as a fan driving current or the amount of work performed, and determination for an occurrence of an abnormality or the expiration of the lifetime of an appliance is performed by comparing a detected air-flow rate with a reference air-flow rate.
  • the determination for the wind condition has been performed by monitoring to determine whether the output of the air-flow rate sensor varies.
  • the fan revolution rate is sometimes adjusted so as to maintain a steady output for the air-flow rate sensor.
  • the wind condition can be detected by monitoring to determine whether the fan revolution rate is varied. The same procedure is employed for monitoring the power of the combustion fan.
  • the determination of the expiration of a lifetime or of an occurrence of an abnormality can be performed by monitoring to ascertain whether the combustion fan is revolving at a required revolution rate or greater, or by monitoring to ascertain whether or not only the output of the air-flow rate sensor is less than is necessary.
  • a single-function water heater (a water heater with only a hot water supply function) has been employed as a combustion appliance.
  • the present invention can be applied to compound water heaters having both a hot water supply function and a supplementary bathtub heating function, or both a hot water supply function and a hydronic heating function, to combustion appliances having a variety of burners, such as bath water heaters, space heating appliances, space cooling appliances, space heating and cooling appliances, and to air conditioners.
  • combustion fan 3 of a draft forcing type has been employed in the above embodiments, a combustion fan 3 of a draft induction type may be employed.
  • a combustion appliance can control combustion by maintaining a low carbon monoxide, hydrocarbon and nitrogen oxide exhaust content, and can prevent in advance the occurrence of incomplete combustion due to a blockage of the appliance with soot, or an unexpected plugging of an outlet port.
  • the relationship between the air-flow rate and the combustion fan revolutions is examined to determine whether or not it is within a normal range.
  • the output of the air-flow rate sensor, or the fan revolution rate is monitored whether there is no external wind condition. Since the determination can be performed without being affected by external conditions, undesirable fault determinations are prevented.
  • the relationship between the air-flow rate and the revolution rate for the combustion fan is monitored.
  • the relationship is shifted from the normal condition to a first range, first, the gas volume supplied to the combustion burner is reduced and an input down operation is performed. If the relationship between the air-flow rate and the revolution rate for the combustion fan is shifted from the normal condition to a second range, it is assumed that the lifetime of the combustion appliance has expired, and combustion is halted. Therefore, unnecessary repair or disposal of a combustion appliance is eliminated.
  • the value output by the air-flow rate sensor since the initial value for the air-flow rate sensor is detected first, the value output by the air-flow rate sensor, which varies depending on the product and the installation environment, can be used appropriately.
  • zero point correction is performed by using the value output by the air-flow rate sensor that is detected when there is no wind condition, so that a barrier due to a transient change of the sensor can be removed.

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  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Regulation And Control Of Combustion (AREA)
EP95930007A 1994-08-31 1995-08-30 Verbrennungsanlage zur überwachung von fehlern oder lebensdauer Withdrawn EP0781966A1 (de)

Applications Claiming Priority (7)

Application Number Priority Date Filing Date Title
JP23073294A JP3566757B2 (ja) 1994-08-31 1994-08-31 燃焼機器
JP230732/94 1994-08-31
JP249565/94 1994-10-14
JP24956594A JP3566758B2 (ja) 1994-10-14 1994-10-14 燃焼器の空気量制御装置およびその方法
JP284403/94 1994-10-24
JP28440394A JP3566765B2 (ja) 1994-10-24 1994-10-24 燃焼装置
PCT/JP1995/001720 WO1996007056A1 (fr) 1994-08-31 1995-08-30 Dispositif de combustion a detection des anomalies de fonctionnement ou de la durabilite

Publications (1)

Publication Number Publication Date
EP0781966A1 true EP0781966A1 (de) 1997-07-02

Family

ID=27331683

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95930007A Withdrawn EP0781966A1 (de) 1994-08-31 1995-08-30 Verbrennungsanlage zur überwachung von fehlern oder lebensdauer

Country Status (4)

Country Link
EP (1) EP0781966A1 (de)
KR (1) KR970704995A (de)
CN (1) CN1159852A (de)
WO (1) WO1996007056A1 (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1130320A1 (de) * 2000-03-03 2001-09-05 IABER S.p.A. Regelanlage für Kessel
US7494337B2 (en) * 2004-04-22 2009-02-24 Thomas & Betts International, Inc. Apparatus and method for providing multiple stages of fuel
US7726386B2 (en) 2005-01-14 2010-06-01 Thomas & Betts International, Inc. Burner port shield
CN109654055A (zh) * 2018-12-19 2019-04-19 珠海格力电器股份有限公司 风压异常的检测方法、检测装置、风机及空调

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Publication number Priority date Publication date Assignee Title
TW294771B (de) * 1995-01-30 1997-01-01 Gastar Co Ltd
CN107036684B (zh) * 2017-05-11 2019-10-22 广东卓信环境科技股份有限公司 一种流量计故障检测方法及装置
US10935238B2 (en) 2018-05-23 2021-03-02 Carrier Corporation Furnace with premix ultra-low NOx (ULN) burner
US20230184433A1 (en) * 2021-12-14 2023-06-15 Wayne/Scott Fetzer Company Electronic Gas/Air Burner Modulating Control

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Publication number Priority date Publication date Assignee Title
JPH02161208A (ja) * 1988-12-14 1990-06-21 Harman Co Ltd 燃焼装置
JP2647584B2 (ja) * 1991-10-30 1997-08-27 山武ハネウエル株式会社 燃焼制御装置
JP2651069B2 (ja) * 1991-10-30 1997-09-10 山武ハネウエル株式会社 燃焼安全装置
JP3008614B2 (ja) * 1991-12-06 2000-02-14 松下電器産業株式会社 給湯機

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9607056A1 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1130320A1 (de) * 2000-03-03 2001-09-05 IABER S.p.A. Regelanlage für Kessel
US7494337B2 (en) * 2004-04-22 2009-02-24 Thomas & Betts International, Inc. Apparatus and method for providing multiple stages of fuel
US7726386B2 (en) 2005-01-14 2010-06-01 Thomas & Betts International, Inc. Burner port shield
CN109654055A (zh) * 2018-12-19 2019-04-19 珠海格力电器股份有限公司 风压异常的检测方法、检测装置、风机及空调

Also Published As

Publication number Publication date
KR970704995A (ko) 1997-09-06
CN1159852A (zh) 1997-09-17
WO1996007056A1 (fr) 1996-03-07

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