EP0898120A1

EP0898120A1 - Combustion equipment and method of judging life of combustion equipment

Info

Publication number: EP0898120A1
Application number: EP97918384A
Authority: EP
Inventors: Naoyuki Gastar Co. Ltd. TAKESHITA; Masanori Gastar Co. Ltd. ENOMOTO
Original assignee: Gastar Co Ltd
Current assignee: Gastar Co Ltd
Priority date: 1996-05-09
Filing date: 1997-05-08
Publication date: 1999-02-24
Also published as: JP3667871B2; JPH09303768A; WO1997042451A1

Abstract

The expiration of the lifetime of a combustion apparatus is determined based on a carbon monoxide density (CO) which is detected by a carbon monoxide detector during combustion when a ventilation system is little affected by wind and a predetermined reference volume or more of fuel is supplied. For example, the combustion performance and the lifetime of the combustion apparatus 10 are examined based on a count by which the CO density measured during combustion exceeds an abnormality value which represents abnormal combustion.

Description

FIELD OF THE INVENTION

The present invention relates to a combustion apparatus having a carbon monoxide density sensor, and a method for determining the lifetime of such a combustion apparatus.

BACKGROUND OF THE INVENTION

A conventional combustion apparatus of this type is disclosed in Japanese Patent Application No. Hei 1-295374 covering the determination of a combustion state. Specifically, the combustion apparatus employs a carbon monoxide density sensor (hereinafter referred to as a CO sensor) to detect the density of the carbon monoxide (hereinafter referred to as CO) contained in exhaust gas exhausted by combustion, and to determine whether an abnormal combustion condition exists, compares the acquired CO density with an abnormality limit value corresponding to the quantity of fuel supplied. When the CO density exceeds the abnormality limit value, an alarm is generated by the combustion apparatus, or when it is ascertained that an abnormal combustion condition exists, the operation of the combustion apparatus is forcibly stopped.
After the release of an alarm or the forcible stopping of the operation of the combustion apparatus, a human operator must assume control of the apparatus to determine the cause and the extent of the abnormality.
However, an increase in the density of the CO in exhaust gases, the result of an abnormal combustion condition, may not necessarily be caused by deterioration, due to an obstruction or the blockage of an air intake or due to a worn out flue ventilation system or heat exchanger, of an apparatus itself. That is, an increase in the CO density could be attributable to a blockage resulting from a bent or damaged ventilation pipe, or to an adverse employment environment condition, such as a strong wind, during which there is an inadequate exhaustion of exhaust gases. Especially when the setting of a combustion fan is such that the combustion apparatus is operating at almost its minimum level of capability, a strong wind can produce an inadequate exhaustion condition which, even when no apparent abnormality in the combustion apparatus is discerned, tends to produce an increase in the CO density.
Therefore, once the CO density has been increased, it must be determined whether the cause of this rise is due to a blockage attributable to the deterioration of the combustion apparatus, to an effect produced by the wind, or to other reasons. As a result, the interval during which the operation of the combustion apparatus is stopped is extended, and this is very inconvenient.
If an increase in the CO density is a result of damage to an apparatus, this can be comparatively easily determined in a short period of time; however, it takes more time and effort to determine whether a blockage is due to the deterioration of an apparatus or to the wind, or to a combination of the two.
In addition, when a rise in the CO density occurs due to a blockage resulting from the deterioration of a combustion apparatus, it is not always easy to determine whether this signals there is a problem involving the safety of operation of the apparatus, i.e., whether the apparatus has reached the end of its useful life, or whether there is no problem concerning the further operation of the apparatus. Therefore, for safety, a part whereat a blockage has occurred is replaced or repaired. However, when a combination of a slight blockage of the apparatus and a temporary strong wind raises the CO density, parts must be replaced or repaired even though there is no problem concerning the safe operation of the combustion apparatus, a very uneconomical procedure.
To resolve these problems, it is one objective of the present invention to provide a combustion apparatus with which abnormal combustion, which is caused by a blockage in the air-intake and flue ventilation system and the heat exchanger, can be accurately determined and a safe operation can be performed, and which can determine an appropriate time for an exchange or a repair of a part based on the operating states of combustion and notify it to a user; and to provide a method for determining the expected lifetime of the combustion apparatus.

DISCLOSURE OF THE INVENTION

To achieve the above objective, according to a first arrangement of the present invention, there is provided a combustion apparatus comprising:
a detector for detecting a carbon monoxide (CO) density in exhaust gases generated by combustion of supplied fuel; and
a controller for determining a lifetime of the combustion apparatus based on the carbon monoxide density detected during combustion under supplying a predetermined reference volume of fuel or more.
In addition, to achieve the above objective, according to a second arrangement, it is provided a combustion apparatus comprising:
a detector for detecting a carbon monoxide (CO) density in exhaust gases generated by combustion of supplied fuel; and
a controller for determining a lifetime of the combustion apparatus based on the carbon monoxide density detected during combustion under supplying a predetermined volume of fuel or more for a predetermined time period.
With this arrangement, whether or not the detected CO density is abnormal can be accurately determined outdoors in the absence of wind. Therefore, the expected lifetime of a combustion apparatus can be determined from a precisely detected CO density.
Specifically, when the combustion apparatus is operated at high power by the supply of a large volume of fuel, the revolution rate of a combustion fan is high, and the above described abnormal combustion, which may be attributed to the effect of wind, seldom occurs. Therefore, the expiration of the lifetime of the combustion apparatus can be precisely determined by employing the CO density which is detected when the operating power of the combustion is high. It is, then, preferable that the reference volume of fuel which is supplied be close to the maximum volume of fuel which can be supplied, and that the reference volume be, for example, 80% of the maximum volume.
Furthermore, according to a third arrangement of the present invention, in the combustion apparatus of the first or the second arrangement, wherein the controller forcibly reduces a maximum volume of the supplied fuel when the detected density exceeds a first density, and the controller stops the combustion when the detected density exceeds a second density during the combustion under the condition that the maximum volume of the supplied fuel is reduced.
Therefore, the useful life of the combustion apparatus can be extended without a determination of the expected lifetime being required.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a diagram for explaining the conditions under which a combustion apparatus according to one embodiment of the present invention is installed;
Fig. 2 is a conceptual diagram illustrating the combustion apparatus according to the embodiment of the present invention;
Fig. 3 is a block diagram illustrating the combustion apparatus according to the embodiment of the present invention;
Fig. 4 is graph showing the relationship between the volume of supplied gas and the revolution rate of a combustion fan when combustion takes place in an improved combustion mode and in a normal mode;
Fig. 5 is a graph showing an example combustion condition for the combustion apparatus of the embodiment of the present invention in a count of combustion; and
Fig. 6 is a flowchart showing the processing performed by the combustion apparatus according to the embodiment of the present invention.

BEST MODE TO CARRY OUT THE INVENTION

One embodiment of the present invention will now be described while referring to the drawings. It should be noted, however, that the technical scope of the present invention is not limited to this embodiment.
A combustion apparatus 10 according to this embodiment of the present invention is installed indoors, as is shown in Fig. 1. Exhaust gases generated by the combustion apparatus 10 during combustion are exhausted to the outside via an exhaust path 19.
Fig. 2 is a schematic diagram illustrating the arrangement of the combustion apparatus 10. In Fig. 2, a burner 13 is located in the lower portion of a combustion chamber 11 in the combustion apparatus 10, and a combustion fan 12 for air ventilation is located under the burner 13. A rotation sensor (not shown) is provided to detect the rotational state of the combustion fan 12.
A heat exchanger 14 is located in the upper portion of the combustion chamber 11. A water pipe (not shown) is connected, for example, to the inlet of the heat exchanger 14, and a hot-water pipe (not shown) is connected to the outlet.
The burner 13 includes a gas nozzle 22 and a nozzle holder 23, a gas pipe 26 which is connected to the burner 13 via a proportioning valve 24, the degree of opening of which is controlled by an actuator 27, and a solenoid valve 25 which can be opened and closed. A gap is defined between the gas inlet of the burner 13 and the distal end of the gas nozzle 22, so that air used for combustion can be supplied.
The exhausted path 19 communicates with the topmost portion of the combustion chamber 11 to introduce a flue located outside the apparatus, and provided in the exhausted path 19 is a CO sensor 48. The CO sensor 48 is a catalytic combustion gas detector which is satisfactorily sensitive and reliable. Specifically, the CO sensor 48 is formed by winding fine platinum wires to form a coil and coating the coil with aluminum, and employs a phenomenon whereof the electric resistance of platinum is increased when an inflammable gas such as CO contacts it and is burned. The CO sensor 48 may consist of a bridge-shaped component, for a detector assembly, which is formed by coating or impregnating a noble metal catalyst with aluminum, and a compensator which does not react with gas. Further, a semiconductor sensor which employs a change in the electric resistance of gas may be employed as the CO sensor 48.
Fig. 3 is a block diagram illustrating a control unit 30 provided for the combustion apparatus 10. The control unit 30 includes a controller C, a memory 31, and a processor 32. In response to a signal from the processor 32, the control unit 30, via a power amplifier 33 and the actuator 27, drives the proportioning valve 24 and controls the volume of supplied fuel. Furthermore, in response to a signal from the processor 32, the control unit 30 drives the combustion fan 12 via a power amplifier 34 and an actuator 37, and controls the volume of the air supplied for combustion.
The controller C receives a signal from the CO sensor 48, and in accordance with this signal, transmits to the actuator, etc., a control signal for controlling the various types of combustion.
In the memory 31 are stored a control program for controlling the combustion apparatus 10 and various constants (which will be described later) used to determine the expected lifetime of the combustion apparatus 10 in accordance with a detected CO density value (hereinafter referred to as a CO value). Employed for the memory 31 are a ROM and a RAM, or a rewritable EEPROM.
The processor 32 performs a process for determining the expected lifetime, which will be described later, based on a signal received from the CO sensor 48 via the controller C and on the various constants stored in the memory 31. The control unit 30 is preferably a microcomputer.
In the thus arranged combustion apparatus 10 in this embodiment, the CO sensor 48 measures the density of the CO generated during combustion, and in accordance with the detected CO value, the control unit 30 examines the combustion performance and the expected lifetime of the combustion apparatus 10, and controls the combustion in accordance with the combustion performance.
First, when the detected CO value exceeds a predetermined abnormality value, the control unit 30 ascertains whether an abnormal combustion has occurred, and employs the frequency of the occurrence of abnormal combustion as a reference for determining the combustion performance and the expiration of the lifetime of the combustion apparatus 10. The abnormality value is a CO value which is equal to or larger than a predetermined density, i.e., the average of the values of the CO which is output every 10 seconds over the course of a two-minute CO sensor detection cycle. Such an abnormality value is, for example, 700 ppm.
The processor 32 of the control unit 30 compares the CO value obtained by the CO sensor 48 with the abnormality value which is stored in advance in the memory 31. When the detected CO value is larger than the abnormality value, the controller C transmits a signal to the power amplifier 34, and via the actuator 37 increases the revolution rate of the combustion fan 12 to supply a larger volume of air to the burner 13. The condition wherein a larger volume of air is supplied is hereinafter called a "combustion improvement mode". When the operating state is shifted to the combustion improvement mode during combustion, the value of a first flag F1, which is set for the control unit 30, is changed to "1", and is maintained at this value until combustion is stopped, in accordance with the relationship between the revolution rate of the combustion fan 12, which supplies the larger volume of air, and the combustion rate.
Fig. 4 is a graph showing the relationship between the volume of gas which is supplied and the revolution rate of the combustion fan during combustion in the combustion improvement mode and in the normal mode. In Fig. 4, when combustion is shifted from the normal mode to the combustion improvement mode, the revolution rate of the combustion fan is increased for combustion for which the same volume of gas is supplied. Once combustion is stopped, the value held by the flag F1 is changed to "0". When the operation is restarted, the CO value is again compared with the abnormality value.
At this time, the rise in the value of the CO in the exhaust gases, which is caused by abnormal combustion, is due to the deterioration of the performance of the apparatus, such as a blockage of the ventilation system or a worn out heat exchanger 14, or to the bending of or damage to the ventilation pipes. A rise in the value of the CO also occurs when exhaustion is not satisfactorily performed because of a strong wind in the installation environment. Particularly when the combustion apparatus is operating at its minimum power because only a small amount of fuel is being supplied, the CO density is increased when exhaustion is insufficient due to wind, and abnormal combustion tends to occur.
When a large volume of fuel is supplied and the combustion apparatus is operated at high power, the revolution rate of the combustion fan is high, and the above described abnormal combustion due to the wind rarely occurs. In this embodiment, therefore, the control unit 30 examines the combustion performance and the expected lifetime of the combustion apparatus 10 by using the frequency at which abnormal combustion occurs during high power combustion, i.e., during a combustion period when the volume of the gas which is supplied is equal to or larger than a predetermined reference volume which is near the maximum volume (e.g., 80% or greater than the maximum gas volume). At this time, since combustion using the reference gas volume or more could be temporarily performed because of the variance in the combustion capability, it is preferable that the frequency at which abnormal combustion occurs be obtained when combustion using the reference gas volume or greater is continued for a predetermined combustion period or longer.
Specifically, a first reference is set for the control unit 30. The first reference consists of a combination, for example, of a volume of gas supplied for combustion and a combustion period of time, the volume of gas which is supplied being close to the maximum volume. For example, for a combustion apparatus 10 having a maximum supplied gas volume of 30,000 kcal/h, the supplied gas volume for the first reference would be 24,000 kcal/h and the combustion time period would be two minutes.
When the control unit 30 detects combustion under the first reference or higher, the value held by a second flag F2 set in the control unit 30 is changed to "1", as will be described in detail later. Once the value held by the flag F2 has been changed to "1", it is maintained at "1" even when the combustion capability is reduced and combustion under the first reference or lower is performed. Thereafter, when combustion is stopped the value held by the second flag F2 is changed to "0".
Fig. 5 is a graph showing the combustion state in a count of combustion, wherein the horizontal axis represents the time while the vertical axis represents the volume of the gas which is supplied. The combustion state under the first reference or higher was performed twice, as is indicated by time periods G and I. In Fig. 5, the value held by the second flag F2 is changed to "1" at combustion time G. Then, even when at time H the combustion is changed to the first reference or lower, the value held by the second flag F2 is maintained at "1". Even when combustion under the first reference or higher is performed at time H, the value held by the second flag F2 is unchanged.
Normally, as the combustion condition approaches the maximum power, the adverse effect on combustion of a blockage of the air-intake and flue ventilation system or the heat exchanger 14 becomes greater, i.e., more CO tends to be produced. When, as is described above, combustion is performed at a low power, due to the effect of wind on the ventilation process the CO value is increased and the combustion state is deteriorated. But as the combustion state approaches the maximum power, the chance that more CO will be generated due to a disturbance, such as the effect produced on ventilation by wind, is reduced. Therefore, when the supplied volume of gas under the first reference is set close to the maximum volume, the probability is increased that it will be possible for the combustion apparatus 10 to determine that the cause of a rise in the density in exhaust gases of the CO generated by abnormal combustion is a blockage of the ventilation system or of the heat exchanger 14.
Fig. 6 is a flowchart for the embodiment of the present invention. It is preferable that this processing be stored as a control program in the memory 31 of the control unit 30, which is a microcomputer. In Fig. 6, when an operation switch is depressed (S1), a hot-water tap (not shown) is opened and a flow sensor (not shown) detects a predetermined flow rate or higher and is turned on (S2). Combustion is then started.
At this time, the combustion mode differs in accordance with a determination number M stored in the memory 31, which will be described later. When at step S3 the determination number M is smaller than 25, normal operation during which the maximum combustion power of the combustion apparatus 10 is not limited is performed (S4A). When the determination number M is equal to or larger than 25, the limited power operation is performed during which the combustion power of the combustion apparatus 10 is the maximum (S4B). Even for a combustion apparatus 10 for which the maximum supplied gas volume at the normal operation is 30,000 kcal/h, the maximum gas volume is limited to 20,000 kcal/h during the limited power operation.
When combustion is started and combustion under the first reference or higher is detected (S5), a check is performed to determine whether the value held by the second flag F2 is "1" (S6). When combustion is detected under the first reference or higher, such as the combustion at time G in Fig. 5, the value held by the second flag F2, which is initially "0", is changed to "1", and the count K for combustion periods which satisfy the first reference is counted (S7). The combustion count K is stored in the memory 31.
When combustion under the first reference or higher is detected at time I in Fig. 5, the value held by the second flag F2 has already been set to "1", and the combustion count K is not counted. That is, during a count of combustion, even when the combustion power is changed as time elapses and combustion under the first reference or higher is performed a plurality of times, the combustion count K is counted only once.
When during combustion under the first reference or higher (combustion at time G and time I in Fig. 5) the CO density detected by the CO sensor 48 is equal to or larger than the abnormal value (S8), and when at step S9 the value held by the first flag F1 is "0", the mode is changed to the combustion improvement mode. The reason for determining at step S9 whether the value held by the first flag F1 is "1" is that the mode need not be changed when the operation in the combustion improvement mode has already been started.
When at step S9 the value held by the first flag F1 is not "1", a "1" is set to the first flag F1, and a count L, according to which the mode is changed to the combustion improvement mode, is counted (S10). The counted combustion improvement mode count L is stored in the memory 31.
When the count K stored in the memory 31 reaches a predetermined count (e.g., ten times), a check is performed to determine whether the current combustion improvement mode count L is equal to or larger than a first detection number L1 (S14). At step S14 the first detection number L1 is 6.
When the count K, according to which combustion under the first reference or higher is performed, is 10 and the combustion improvement mode count L, according to which the mode is changed to the combustion improvement mode is 6 or larger because of the rise in the CO value, a determination count M is counted by one (S15). The determination count M is stored in the memory 31.
The determination count M is a parameter which is counted when the CO value, which is detected while the combustion apparatus 10 performs combustion at a high power, tends to be equal to or larger than an abnormality value. Therefore, as will be described later, the lifetime of the combustion apparatus 10 is examined based on the determination count M, so that the expiration of the lifetime of the combustion apparatus 10 can be determined accurately.
When, at step S15, the determination count M is counted, the values held by the combustion count K and the combustion improvement mode count L stored in the memory 31 are reset (S16). As is described above, each time the combustion count K reaches 10, the combustion improvement mode count L is read from the memory 31, and when the count L is equal to or larger than the first detection number L1, the determination count M is counted.
When the determination count M exceeds a first determination number M1 (e.g., 50) (S17), it is assumed that the limit of the safe operation of the combustion apparatus 10 has been reached and the life of the apparatus 10 is terminated. The operation of the combustion apparatus 10 is then forcibly stopped (S18).
Preferably, when the determination count M is equal to or smaller than the first determination number M1 and is equal to or larger than a second determination number M2 (e.g., 25), which is smaller than the first determination number M1 (S19), it is assumed that deterioration of the combustion performance of the combustion apparatus 10 has occurred, even though the lifetime of the apparatus 10 has not expired, and that the combustion power should be limited. The maximum degree to which the proportioning valve 24 is opened is limited, as is the maximum volume of gas supplied to the combustion apparatus 10, so that combustion is performed in accordance with the limited power operation (step S20). For a combustion apparatus 10 having a maximum volume of supplied gas of 30,000 kcal/h during normal operation, the maximum volume of gas supplied during a limited power operation is limited to 20,000 kcal/h.
Therefore, when a combustion apparatus 10 begins a limited power operation, a user can understand that, as for the CO value, there is no safety problem, even when the combustion apparatus 10 is used continuously and even though a blockage has occurred in the ventilation system and the heat exchanger 14.
When, at step S14, the combustion improvement mode count L is equal to or smaller than the first detection number L1 and larger than the second detection number L2 (e.g., 2) (S21), it is assumed that there has been no deterioration of the performance of the combustion apparatus 10, Therefore, the determination count M is not counted, and the combustion count K and the combustion improvement mode count L stored in the memory 31 are reset (S13).
When at step S21 the combustion improvement mode count L is smaller than the second detection number L2, it is assumed that the mode has been changed to the combustion improvement mode, not because of the deterioration of the combustion performance of the combustion apparatus 10 but because of a disturbance, such as sudden wind. If there is deterioration of the combustion performance of the combustion apparatus 10, the mode tends to be switched to the combustion improvement mode and the combustion improvement mode count L is increased, while in the normal combustion state, the mode is seldom changed to the combustion improvement mode only because of a temporary combustion deterioration attributable to the wind and the combustion improvement mode count L is small. Therefore, in this case, when the determination count M is smaller than the second determination number M2 (e.g., 25), i.e., during a normal operation, the determination count M is reset (S23). When at step S19 the determination count M is equal to or larger than the second determination number M2 (= 25), i.e., during a limited power operation, it is assumed that there has been no deterioration of the combustion performance during the limited power operation. Therefore, the determination count M is set to a value of 25, for example, held by the second determination number M2, which is the threshold value for switching the operation to the limited power operation.
When at step S12 the combustion is stopped, the values held by the first and the second flags F1 and F2 are set to "0", as is described above (S26).
Furthermore, when, at step S3, the determination count M is equal to or larger than 25 and the combustion apparatus 10 has entered the limited power operating state (S4B), the control unit 30 performs the same processing, for combustion under the second reference or higher instead of under the first reference, which is set in advance in the control unit 30 as a combination of a combustion time period and a volume of gas, supplied for combustion, which is close to the maximum volume of gas (20,000 kcal/h) supplied during the limited power operation. According to the second reference, the volume of gas supplied is defined as 16,000 kcal/h while the maximum gas volume supplied is 200,000 kcal/h, and the continuous combustion time period is two minutes.
Specifically, the combustion count P for combustion under the second reference or higher is counted, and the combustion improvement mode count L is also counted. When the combustion count P, for example 10, is reached for the second or higher reference (S11), at steps S14 and S21 the combustion improvement mode count L acquired during ten counts of combustion are compared with a third detection number L3 and a fourth detection number L4, both of which are stored in advance in the memory 31. The third and the fourth detection numbers L3 and L4 may be the same as the first and the second detection numbers L1 and L2. Since the effect produced by wind is great in a limited power operation during which the revolution rate of the combustion fan is reduced, the third and the fourth detection numbers L3 and L4 may be larger than L1 and L2, or may otherwise differ from them.
When the combustion improvement mode count L is equal to or larger than the third detection number L3, the determination count M is counted by one. Hereinafter each time the combustion improvement mode count L is equal to or larger than the third detection number L3, the determination count M will be counted (S15).
When the combustion improvement mode count L is smaller than the third detection number L3 and equal to or smaller than the fourth detection number L4 (S21), the determination count M is not counted and the same count is maintained, while the combustion count P and the combustion improvement mode count L are reset.
When the combustion improvement mode count L is equal to or smaller than the fourth detection number L4 (S21), as is described above, the determination count M is set to 25, which is the count held by the second determination number M2 (S24).
When the above process is repeated and the determination count M reaches the first determination number M1 (e.g., 50) stored in the memory 31 (S17), the control unit 30 ascertains that the lifetime of the combustion apparatus 10 has expired, and forcibly stops the operation of the combustion apparatus 10 (S18).
When the operation of the combustion apparatus 10 is forcibly stopped, this enables a user to understand that the lifetime of the combustion apparatus 10 has expired.
In this embodiment, specific numbers are employed for the first and the second references, the detection numbers and the determination numbers, but the numbers that can be used are not limited to these specific numbers.
According to the method of this embodiment for determining the expiration of the lifetime of a combustion apparatus, either the combustion power of a combustion apparatus 10 is changed in accordance with the occurrence of a blockage of the ventilation system and the heat exchanger 14, or the operation of the combustion apparatus 10 is forcibly stopped, so that operational safety is ensured and so that a user can very easily understand that the lifetime of the combustion apparatus 10 has expired.
In another embodiment of the present invention, for a combustion apparatus having a combustion power of 30,000 kcal/h, a plurality of reference combustion rates are set so that a determination count is counted by one each time combustion under 30,000 kcal/h to 20,000 kcal/h occurs; that the determination count M is counted by 0.2 each time combustion under 20,000 kcal/h to 10,000 kcal/h occurs; and that the determination count M is counted by 0.01 each time combustion under 10,000 kcal/h to 5,000 kcal/h occurs. And the values by which the determination numeral is counted for the reference combustion rates are weighted (for example, at step S7 K = K + 0.2, and at step S10 L = L + 0.2), so that expiration of the lifetime can be examined even for a super large water heater which in normal operation is generally operated at only the middle combustion rate.
In addition, when instead of the above three levels the heat produced by combustion may not be thus divided, if a CO density of 700 ppm is generated for ten minutes while combustion is taking place at almost the maximum combustion power, the determination count is counted by one; and if a CO density of 100 ppm is generated for ten minutes while combustion is taking place at almost the minimum combustion power, the determination count M is also counted by one.

INDUSTRIAL USABILITY

According to the present invention, in an outdoor environment where the effect of wind is not a factor, a combustion apparatus can determine whether a CO density value is abnormal. Therefore, the expiration of the lifetime of the combustion apparatus can be determined by using an accurate CO density value.
Furthermore, according to the present invention, when the CO density value exceeds a predetermined value, a combustion apparatus can continue to be operated while the maximum volume of gas which is supplied is limited. Therefore, the lifetime of the apparatus can be extended without an unnecessary lifetime determination process being required.
In addition, the expiration of the lifetime of a combustion apparatus can be precisely determined by using the determination count M.
As is described above, the combustion apparatus of the present invention is very safe and economical, and efficient maintenance for it is ensured.

Claims

A combustion apparatus comprising:

a detector for detecting a carbon monoxide density in exhaust gases generated by combustion of supplied fuel;
and

a controller for determining a lifetime of the combustion apparatus based on the carbon monoxide density detected during combustion under supplying a predetermined reference volume of fuel or more.
A combustion apparatus comprising:

a detector for detecting a carbon monoxide density in exhaust gases generated by combustion of supplied fuel;
and

a controller for determining a lifetime of the combustion apparatus based on the carbon monoxide density detected during combustion under supplying a predetermined volume of fuel or more for a predetermined time period.
The combustion apparatus according to claim 1 or 2, wherein the controller forcibly reduces a maximum volume of the supplied fuel when the detected density exceeds a first density, and the controller stops the combustion when the detected density exceeds a second density during the combustion under the condition that the maximum volume of the supplied fuel is reduced.
The combustion apparatus according to claim 1, 2 or 3, wherein the controller determines the lifetime of the combustion apparatus based on a detection count of the carbon monoxide density higher than a predetermined density.
The combustion apparatus according to claim 4, wherein the controller counts the detection count in a predetermined count of combustion and determines the lifetime of the combustion apparatus when the detection count exceeds a predetermined detection number.
The combustion apparatus according to claim 4, wherein the controller counts the detection count in a predetermined count of combustion, determines the lifetime of the combustion apparatus when the detection count exceeds a predetermined detection number, and stops combustion when the count of the lifetime determination exceeds a predetermined determination number.
The combustion apparatus according to claim 4, wherein the controller counts the detection count in a predetermined count of combustion, adds a certain number to a determination count for determining a lifetime when the detection count exceeds a predetermined detection number, and stops the combustion when the determination count exceeds a predetermined determination number.
The combustion apparatus according to claim 4, wherein the controller counts the detection count in a predetermined count of combustion, adds a certain number to a determination count for determining a lifetime when the detection count exceeds a predetermined detection number, and stops the combustion when the determination count exceeds a first determination number, and the controller forcibly reduces the maximum volume of supplied fuel when the determination count exceeds a second determination number smaller than the first determination number.
The combustion apparatus according to claim 1 to 8, wherein the predetermined volume for fuel is substantially close to the maximum volume of fuel.
The combustion apparatus according to claim 9, wherein the predetermined volume is approximately 80% of the maximum volume of fuel.
A combustion apparatus comprising:

a detector for detecting a carbon monoxide density in exhaust gases generated by combustion of supplied fuel; and

a controller for counting a detection count of the carbon monoxide density higher than a predetermined density in a predetermined count of combustion, adding a certain number set based on the volume of the supplied fuel to a determination count for determining a lifetime when the detection count exceeds a predetermined detection number, and stopping the combustion when the determination count exceeds a predetermined determination number.
A combustion apparatus comprising:

a detector for detecting a carbon monoxide density in exhaust gases generated by combustion of supplied fuel;
and

a controller for determining a lifetime of the combustion apparatus based on the carbon monoxide density detected during combustion under supplying a predetermined reference air volume or more.
A combustion apparatus comprising:

a detector for detecting a carbon monoxide density in exhaust gases generated by combustion of supplied fuel;
and

a controller for determining a lifetime of the combustion apparatus based on the carbon monoxide density detected during combustion under supplying a predetermined air volume or more for a predetermined time period.
A method for determining a lifetime of a

detecting a carbon monoxide density in exhaust gases generated by combustion of supplied fuel; and

determining the lifetime based on the carbon monoxide density detected during combustion under supplying a predetermined reference volume of fuel or more.
A method for determining a lifetime of a combustion apparatus comprising the steps of:

detecting a carbon monoxide density in exhaust gases generated by combustion of supplied fuel; and

determining the lifetime based on the carbon monoxide density detected during combustion under supplying a predetermined volume of fuel or more for a predetermined time period.