JP2636153B2 - Incomplete combustion detector for combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an incomplete combustion detecting device for detecting incomplete combustion of a combustion device.

[0002]

2. Description of the Related Art Conventionally, as this kind of incomplete combustion detecting device, a CO sensor 20 is provided at an outlet 6 of a water heater A shown in FIG.
It is known that the inside CO concentration is calculated, the incomplete combustion is determined when the CO concentration exceeds a predetermined reference value, and the combustion of the water heater A is stopped by the combustion control device 4.

A water heater A is provided with a gas burner 2 for performing combustion in a combustion housing 1, and a combustion fan 3 supplies combustion air X of the gas burner 2 to the combustion housing 1 to perform combustion. The combustion control device 4 supplies gas to the gas burner 2, ignites the gas burner 2, and controls the combustion fan 3. The combustion housing 1 is provided with an inlet 5 for the combustion air X below, and an exhaust port 6 for discharging the combustion exhaust gas Z to the outside above, and a heat exchanger 7 above the gas burner 2 in the combustion housing 1. Are arranged.

[0004] The incomplete combustion detection device comprises a CO sensor 2
0 and a controller 21 for controlling the combustion control device 4. As shown in FIG. 5, the controller 21 defines a relational expression between the CO concentration output of the CO sensor 20 and the actual CO concentration as C.
An output characteristic storage means 22 for storing the output characteristic of the O sensor 20, and a CO concentration determination used for determining incomplete combustion from the CO concentration output of the CO sensor 20 and the relational expression stored in the output characteristic storage means 22. CO concentration determination value calculating means 23 for calculating a value, and incomplete combustion for determining incomplete combustion of the water heater A by comparing the CO concentration determination value with a preset reference value stored in a reference value ROM 24. The microcomputer includes a determination unit 25 and a combustion control unit 26 that stops the combustion of the water heater A when incomplete combustion is detected by the incomplete combustion determination unit 25.

When the CO sensor 20 detects the CO concentration in the exhaust gas Z at the outlet 6, the CO sensor 20 converts the CO concentration into an electric signal according to a specific output characteristic and outputs the electric signal. The intensity corresponds to the CO concentration. The output characteristic becomes a linear function of the actual CO concentration as shown by a solid line M in FIG. 4 by performing a predetermined temperature correction on the output of the CO sensor 20.

Therefore, in the conventional incomplete combustion detecting device, a relational expression of a straight line M indicating the relation between the CO concentration output and the actual CO concentration is stored in the initial set value storage means 22 as the output characteristic of the CO sensor 20. , CO concentration determination value calculation means 2
In step 3, the actual CO concentration corresponding to the CO concentration output is calculated by applying the CO concentration output of the CO sensor 20 to the relational expression of the straight line M. For example, the CO sensor 20 at this time
Assuming that the concentration output is x, the CO concentration output x is represented by a straight line M in FIG.
C _M corresponding to is calculated as the actual CO concentration. Wherein in incomplete combustion detecting apparatus, then, the CO concentration C and _M and the CO concentration determination value, the C in an incomplete combustion determination means 25
O concentration determination value is compared with a reference value stored in the C _M and the reference value ROM 24, it determines that the incomplete combustion when CO concentration determination value C _M exceeds the reference value.

The output characteristics of the CO sensor 20 tend to fluctuate due to an impact. When the fluctuations occur, the output characteristics become a straight line N shown by a virtual line in FIG. 4, and the straight line N is also a linear function of the actual CO concentration. And the rate of change of the actual CO concentration with respect to the CO concentration output is the same as the straight line M (parallel to the straight line M).
If the error between the CO concentration C _M corresponding to the O concentration output x and the CO concentration C _N corresponding to the CO concentration output x of the CO sensor 20 on the straight line N is within an allowable range, the CO concentration may be slightly changed. the actual CO concentration corresponding to the output x as Examples C _M can perform the determination of incomplete combustion.

However, the variation accumulates during long-term use, and the CO concentration C calculated from the straight line M
And _M, when expanded error between the true CO concentration C _N, incomplete combustion is disadvantageous in that no correctly detected. In addition, the output characteristics of the CO sensor may fluctuate significantly due to impacts during shipping and transportation or installation, and in such a case, incomplete combustion may not be accurately detected.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to an incomplete combustion detection device for a combustion apparatus which can solve such inconvenience and can detect incomplete combustion more accurately even if the output characteristics of the CO concentration detecting means fluctuate. The purpose is to provide.

[0010]

In order to achieve the above object, an apparatus for detecting incomplete combustion of a combustion apparatus according to the present invention comprises: a CO concentration detection means for detecting a CO concentration in exhaust gas from a combustion apparatus; The relational expression between the CO concentration output of the detection means and the actual CO concentration, and the initial set value of the zero point indicated by the CO concentration output of the CO concentration detection means corresponding to the case where the actual CO concentration is zero in the relational expression Output characteristic storing means for storing as output characteristics of the CO concentration detecting means;
CO concentration determination value calculation means for calculating a CO concentration determination value used for determination of incomplete combustion from the CO concentration output of the concentration detection means and the relational expression stored in the output characteristic storage means; An incomplete combustion judging means for judging incomplete combustion of the combustion equipment by comparing the value with a preset reference value; and combustion control means for stopping combustion of the combustion equipment by the judgment of the judging means. In the incomplete combustion detection device for the combustion equipment, when the time during which the combustion equipment is not burning reaches a predetermined time, C
Correction value calculating means for calculating a correction value of the zero point from a difference between the O concentration output and the initial set value of the zero point stored in the output characteristic storage means; and a zero value of the zero point calculated by the correction value calculating means. Correction value storage means for storing a correction value, and a correction relation for calculating a correction relational expression from the zero-point correction value stored in the correction value storage means and the relational expression stored in the output characteristic storage means. Formula calculation means, wherein the CO concentration determination value calculation means calculates a CO concentration determination value from the CO concentration output of the CO concentration detection means and the correction relational expression calculated by the correction relational expression calculation means. Features.

[0011] In the incomplete combustion detection device of the present invention, the correction value calculating means determines the correction value of the zero point when a time period during which the combustion device stops burning after stopping the combustion reaches a predetermined time. It is characterized in that it is calculated. Further, in the incomplete combustion detection device of the present invention, the correction value calculating means may calculate the correction value of the zero point when a time during which the combustion device is not burning after the energization is started reaches a predetermined time. It is characterized in that it is calculated.

Further, in the incomplete combustion detecting device of the present invention,
As the correction value storage unit, a readable and writable nonvolatile storage unit (EEPROM) is preferably used because it can be electrically written or erased and can be stored even when power supply is stopped due to a power failure or the like. .

[0013]

In the combustion device, the CO concentration in the atmosphere around the portion where the CO concentration detecting means is provided is high during combustion, but no new CO is generated when not burning. Therefore, the atmosphere is gradually replaced by the atmosphere. Although a small amount of CO exists in the atmosphere, a small amount of CO in the atmosphere does not cause CO poisoning in the human body, so that the CO concentration can be approximated to zero.

Therefore, in the incomplete combustion detecting device according to the present invention, when the CO concentration detecting means is considered to have fluctuated in the output characteristics, the time during which the combustion equipment is not burning reaches a predetermined time, By detecting the CO concentration output of the CO concentration detecting means when the atmosphere is sufficiently replaced with the atmosphere, the CO concentration with respect to the CO concentration in the atmosphere is detected.
The output of the density detecting means is confirmed.

At this time, the correction value calculating means sets a difference between the CO concentration output with respect to the CO concentration in the atmosphere and an initial set value of the zero point stored in the output characteristic storing means as a zero point correction value. By calculating, the magnitude of the fluctuation of the output characteristic is recognized. Then, the correction value of the zero point is stored in the correction value storage means, and is used for determination of incomplete combustion in the next and subsequent times.

In the determination of incomplete combustion after the next time, first,
The relational expression between the CO concentration output of the CO concentration detection means and the actual CO concentration stored in the output characteristic storage means is corrected by the correction relational expression calculation means using the correction value at the zero point. An equation is derived. This corrected relational expression is based on the assumption that the CO concentration in the atmosphere is zero.
As described above, since the CO concentration in the atmosphere does not cause CO poisoning in the human body, there is no problem in using this concentration as a substantially zero point.

Next, by substituting the CO concentration output of the CO concentration detecting means into the corrected relational expression by the CO concentration determining value calculating means, the CO concentration determining value used for determining incomplete combustion is obtained. Is calculated. The incomplete combustion determination means compares the CO concentration determination value with a predetermined reference value to determine incomplete combustion. When it is determined that the combustion is incomplete, the combustion control means performs the combustion control. The combustion of the equipment is stopped.

According to the incomplete combustion detection device of the present invention, when the non-combustion time reaches a predetermined time as described above, the correction value calculating means calculates the CO concentration output with respect to the CO concentration in the atmosphere. Since the difference between the zero point and the initial set value stored in the output characteristic storage means is calculated as a zero point correction value, the relational expression indicating the output characteristic of the CO concentration detection means indicates that the CO concentration in the atmosphere is zero. Is corrected as a point, and even if the output characteristics fluctuate, the CO
The error between the CO concentration determination value calculated from the concentration output and the actual CO concentration is reduced, and incomplete combustion is detected more accurately.

In the incomplete combustion detection device according to the present invention, the correction value calculating means calculates the correction value at the zero point when the time during which the combustion device stops burning after stopping the combustion reaches a predetermined time. By doing so, accumulation of fluctuations in output characteristics due to long-term use is prevented, and incomplete combustion is detected more accurately.

When the combustion device restarts combustion within the predetermined time after stopping the combustion, the correction value of the zero point is not calculated, but the combustion device performs combustion indefinitely. There is a pause period in which the time during which combustion is not necessarily performed reaches a predetermined time without being performed. Therefore,
The correction value calculating means can reliably calculate the correction value of the zero point by operating while capturing the idle period, thereby preventing the accumulation of fluctuations in output characteristics.

The output characteristics of the CO concentration detecting means may fluctuate greatly due to an impact during transportation or installation of the combustion equipment. When the combustion equipment is installed, combustion is often not yet started immediately after the start of energization, so that the correction value calculating means immediately corrects the zero point according to the CO concentration in the atmosphere at that time. The value may be calculated.

However, in the incomplete combustion detection device, the power supply is started immediately after installation of the combustion equipment, and after the power supply is stopped due to an accident such as an artificial or blackout, the power is restored and the power supply is performed. If the correction value of the zero point is calculated immediately after the energization is started as described above, the combustion is interrupted by the stop of the energization, and the power is restored immediately after that. There is a possibility that the CO concentration in the atmosphere around the portion where the CO concentration detecting means, which has become high due to the sudden stop of combustion, is set as the zero point correction value.

Therefore, in the incomplete combustion detection device according to the present invention, when the time during which combustion is not performed after the commutation of the combustion equipment reaches a predetermined time, the correction value calculating means corrects the zero point. By calculating the value, the correction value of the zero point is calculated after the atmosphere around the part where the CO concentration detection means is installed is replaced with the atmosphere, so that the combustion device It is no longer necessary to distinguish between after installation and after power is turned off and power is restored.

By correcting the correction value of the zero point as described above, immediately after the installation, when the combustion is started, the output characteristic of the CO concentration detecting means due to the impact during transportation and at the time of installation is determined. Fluctuations are corrected, and incomplete combustion is detected more accurately. Further, in the case where the power supply is stopped and the power is restored, the zero point is not corrected to the high CO concentration due to the sudden interruption of the combustion, and the incomplete combustion is detected more accurately when the combustion is restarted. You.

Further, in the incomplete combustion detecting device of the present invention,
Even if the power supply is stopped by using an EEPROM as the correction value storage means, the correction value of the zero point calculated last time is stored and held. Therefore, as described above, due to an accident such as a power failure or artificially, After power is turned off and power is restored,
When the combustion is restarted before the non-combustion time has not reached the predetermined time, the correction value of the zero point stored in the correction value storage means is not erased. Therefore, after the power recovery, by calculating the correction relational expression using the correction value of the zero point stored in the EEPROM, the incomplete combustion is detected more accurately when the combustion is restarted. You.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus for detecting incomplete combustion of a combustion apparatus according to the present invention will be described in further detail with reference to the accompanying drawings. FIG. 1 is an explanatory sectional view of a water heater provided with an incomplete combustion detection device of the present embodiment, FIG. 2 is a block diagram showing a configuration of the incomplete combustion detection device of the present embodiment, and FIG. FIG. 4 is a flowchart illustrating the operation of the incomplete combustion detection device according to the embodiment. FIG. 4 is a graph illustrating the output characteristics of the CO sensor in the incomplete combustion detection device according to the embodiment.

As shown in FIG. 1, a forced-combustion gas water heater A includes a gas burner 2 for performing combustion in a combustion housing 1.
The combustion fan 3 supplies combustion air X of the gas burner 2 to the combustion housing 1. In addition, water heater A
The combustion control device 4 supplies gas to the gas burner 2, ignites the gas burner 2, and controls the combustion fan 3. The combustion housing 1 has an inlet 5 for the combustion air X at the bottom and an outlet 6 at the top for discharging the combustion exhaust gas Z to the outside.
Are provided respectively. Further, a heat exchanger 7 is disposed above the gas burner 2 in the combustion housing 1.
The gas burner 2 includes a burner group 8 that forms a flame, and a nozzle tube 10 that is located below the burner group 8 and has an ejection port 9.
Consists of The gas burner 2 has a gas pipe 1.
The fuel gas Y is supplied through 1. The combustion fan 3 has turbo-type blades.

The combustion control device 4 includes a water governor 12, a water amount sensor 13, a thermistor 14, an original gas solenoid valve 15, a main solenoid valve 16, a governor gas proportional solenoid valve 17, and an igniter 1.
8, a frame rod 19, a CO sensor 20, and a controller 21 for controlling these. The incomplete combustion detection device of the present embodiment includes a CO sensor 20 for detecting the CO concentration in the exhaust gas of the water heater A, and a controller 21.

The controller 21, as shown in FIG.
The relational expression between the CO concentration output of the O sensor 20 and the actual CO concentration, and the initial set value of the zero point indicated by the CO concentration output of the CO sensor 20 corresponding to the case where the actual CO concentration is zero, is the output of the CO sensor 20. A CO characteristic determination value used for determining incomplete combustion is calculated from the output characteristic storage means 22 for storing as characteristics and the CO concentration output of the CO sensor 20 and the relational expression stored in the output characteristic storage means 22.
Concentration determination value calculation means 23; incomplete combustion determination means 25 for comparing the CO concentration determination value with a preset reference value stored in a reference value ROM 24 to determine incomplete combustion of the combustion device; The microcomputer includes a combustion control means 26 for stopping the combustion of the water heater A when incomplete combustion is detected by the incomplete combustion determination means 25. The controller 21 further monitors the energization of the water heater A via the combustion control means 26, and the combustion control means 26 and the energization monitoring section 27 detect that the water heater A is not burning. A 30-minute timer 28 that measures the time when combustion is not performed, a CO-concentration output detection unit 29 that detects the CO-concentration output of the CO sensor 20 when the 30-minute timer 28 times out, and the CO-concentration output and the output. Correction value calculating means 30 for calculating a zero-point correction value from a difference between the zero-point initial setting value stored in the characteristic storage means 22;
A writing unit 32 for writing to an EEPROM 31 provided outside of the device; a reading unit 33 for reading the correction value of the zero point from the EEPROM 31; And a correction relational expression calculating means 34 for calculating a correction relational expression from the relational expression. The CO concentration determination value calculation means 23 calculates the CO concentration from the CO concentration output of the CO sensor 20 and the correction relational expression calculated by the correction relational expression calculation means 34.
A density determination value is calculated.

Next, the basic operation of the incomplete combustion detecting device according to the present embodiment will be described with reference to FIGS.

First, when the controller 21 detects the open state of a hot water tap (not shown) by the water amount sensor 13, the combustion control means 26 controls the original gas solenoid valve 15 and the main solenoid valve 1.
6. Open the proportional solenoid valve 17 and supply the fuel gas Y to the gas burner 2. Next, the combustion fan 3 is driven to ignite the gas burner 2 to perform combustion. At the same time,
The CO sensor 20 is energized.

Further, when the hot water tap is closed, the controller 21 detects this by the water quantity sensor 13 and
The combustion control means 26 closes the original gas solenoid valve 15, the main solenoid valve 16, and the proportional solenoid valve 17, stops driving the combustion fan 3, and extinguishes the gas burner 2.

The controller 21 uses the CO concentration determination value calculation means 23 to store the CO concentration output of the CO sensor 20 and the output characteristic storage means 22 during the combustion of the gas burner 2.
The CO concentration in the combustion exhaust gas Z is calculated as a CO concentration determination value from the relational expression indicating the output characteristic of the CO sensor 20 stored in
The O concentration determination value is compared with the reference value stored in the reference value ROM 24. When the CO concentration determination value exceeds the reference value, the incomplete combustion determination means 25 determines that the combustion is incomplete and activates the combustion control means 26 to cause the original gas solenoid valve 15, the main solenoid valve 16, The valve 17 is closed, the drive of the combustion fan 3 is stopped, the gas burner 2 is extinguished, and the power supply to the CO sensor 20 is stopped.

However, the output characteristics of the CO sensor 20 tend to fluctuate due to an impact.
The error between the CO concentration output value of the sensor 20 and the CO concentration determination value calculated from the relational expression stored in the output characteristic storage means 22 and the actual CO concentration increases, and incomplete combustion is not accurately detected. Therefore, in the incomplete combustion detection device of the present embodiment, when the time during which the water heater A is not burning reaches the predetermined time, the relational expression indicating the output characteristic of the CO sensor 20 is changed to the CO concentration in the atmosphere. Is corrected to zero, so that even if the output characteristics fluctuate, CO
The error between the CO concentration determination value calculated from the CO concentration output of the sensor 20 and the actual CO concentration is reduced so that incomplete combustion can be detected more accurately.

Next, the operation of correcting the relational expression indicating the output characteristic of the CO sensor 20 in the incomplete combustion device of this embodiment will be described with reference to FIGS.

As shown in FIG. 3, when the water heater A is installed and turned on (STEP 1), the controller 21 starts energizing the CO sensor 20 (STEP 1).
2). The state of the water heater A is detected by the combustion control means 26 and the power monitoring unit 27. In a state where power is supplied but combustion is not started, the 30-minute timer 28 operates (STEP 3), and STEPs 4 to 5 are performed. When it is recognized that the non-combustion state has reached 30 minutes, the correction value calculating means 30 calculates a zero-point correction value in STEP6. The calculation of the zero point correction value in STEP 6 is performed as follows.

First, a relational expression indicating the relationship between the CO concentration output of the CO sensor 20 set at the time of shipment from the factory and the actual CO concentration is stored in the output characteristic storage means 22, and if the actual CO concentration is zero in the relational expression. CO sensor 2 corresponding to
The initial setting value of the zero point indicated by the CO concentration output of 0 is CO
It is stored as the output characteristic of the sensor 20. The relational expression is represented by a straight line M shown in FIG. 4, and the initial set value of the zero point is represented by the CO concentration output m of the CO sensor 20 when the actual CO concentration is zero on the straight line M.

When the output characteristics of the CO sensor 20 fluctuate, the straight line M moves in parallel and the relational expression represented by the straight line N is obtained. Accordingly, the relationship between the CO concentration output of the CO sensor 20 after the fluctuation and the actual CO concentration is shown by a straight line N. If the CO concentration output of the CO sensor 20 is x, the CO concentration calculated from the relational expression of the straight line M Although the determination value is C _M, the true CO concentration becomes C _N corresponding to CO concentration output x in equation of the straight line N.

At this time, when the CO concentration output of the CO sensor 20 is detected by the CO concentration output detection unit 29, the atmosphere around the portion where the CO sensor 20 is installed is in the atmosphere when the water heater A is not used immediately after installation. Therefore, the CO concentration output with respect to the CO concentration in the atmosphere is detected in accordance with the output characteristic indicated by the straight line N. Since the CO concentration in the atmosphere is extremely small and does not cause CO poisoning in the human body, this CO concentration output is used as an approximate value of the CO concentration output n.

Next, the correction value calculation means 30 calculates the CO concentration output (≒ n) for the CO concentration in the atmosphere shown in FIG. 4 and the initial set value m of the zero point stored in the output characteristic storage means 22. Is calculated as the correction value of the zero point, the magnitude of the fluctuation of the output characteristic is recognized. Next, the correction value Δt is stored in the EEPROM 31 by the writing unit 32.
And stored in the EEPROM 31.

Immediately after the installation of the water heater A, the correction value of the zero point may be calculated at any time, but when the state in which the water heater A is not burning reaches 30 minutes as described above. By calculating the correction value of the zero point, the state in which the energization in STEP 2 is started does not need to be distinguished from the later-described power restoration after the energization is stopped, which is convenient. When the calculation of the correction value of the zero point is completed, the controller 21 stops supplying power to the CO sensor 20, and the water heater A enters a state of waiting for the start of combustion (STEP 7).

Next, when the combustion of the water heater A is started in STEP7, energization of the CO sensor 20 is started by the controller 21 (STEP8), and incomplete combustion is detected by the incomplete combustion determination means 25 in STEP9. Will be ST
The detection of incomplete combustion in EP9 is performed as follows.

First, the reading unit 33 causes the EEPROM 31
Is read from the zero point correction value Δt stored in
The CO sensor 2 indicated by the straight line M in FIG. 4 stored in the output characteristic storage means 22 by the correction relational expression calculation means 34
The relational expression indicating the output characteristic of 0 is corrected using the correction value Δt at the zero point, and the correction relational expression indicated by the straight line N in FIG. 4 is derived. Next, C concentration determination value calculating means 23 calculates C
By applying the CO concentration output of the O sensor 20 to the correction relational expression shown by the straight line N in FIG. 4, a CO concentration determination value used for determining incomplete combustion is calculated. And
The incomplete combustion determination means 25 compares the CO concentration determination value with a preset reference value stored in the reference value ROM 24. When the CO concentration determination value exceeds the reference value, incomplete combustion is determined. Is detected.

In step 9, if incomplete combustion is not detected, S
In TEP10, the combustion of water heater A is stopped, and power monitoring unit 2
If it is detected in step 7 that the water heater A is continuously energized, it is recognized that the stop of the combustion is not due to a power failure or an artificial stop of energization (STEP 11), and the 30-minute timer 28 is activated (STEP 11). (STEP 12). And ST
If it is recognized in EP13 to EP14 that the state in which combustion is not performed has reached 30 minutes, a correction value Δt of the zero point is calculated in STEP15 in the same manner as in STEP6.

Immediately after the water heater A stops burning, C
The atmosphere around the portion where the O sensor 20 is installed is C
If the O concentration is high, but the water heater A is not burning for 30 minutes, the atmosphere around the portion where the CO sensor 20 is installed is sufficiently replaced with the atmosphere. Therefore, at this time, the CO sensor 20
Is detected, the CO concentration output with respect to the CO concentration in the atmosphere is detected in accordance with the output characteristic indicated by the straight line M in FIG. 4, and the CO concentration output corresponds to the case where the actual CO concentration is zero. CO concentration output m of sensor 20
Is used as an approximation of

Next, in STEP 15, after the correction value Δt of the zero point is written into the EEPROM 32 by the writing unit 31, the controller 21 stops the energization of the CO sensor 20, but when the energization is continued (STE).
In P16), the process returns to STEP7, and the operations after STEP7 are repeated. When the power supply is stopped artificially or due to a power failure in STEP 16, the state returns to the state immediately after installation.

If the CO sensor 20 is continuously energized, its durability will be reduced. Therefore, it is desirable to energize only during combustion. However, since the output of the CO sensor 20 is not stabilized immediately after the energization is started, even if the water heater A once stops the combustion as in the case of using the shower, the combustion is started again in a short time. If the CO sensor 20 is energized only during combustion as described above, it is difficult to detect incomplete combustion. Therefore, in general, the power supply to the CO sensor 20 is not stopped immediately after the combustion is stopped, and the power supply state is maintained for a certain period of time, in case the combustion of the water heater A is restarted within a short time. Therefore, the time during which this energized state is maintained is determined by the CO sensor 20.
If the setting is made in accordance with the time at which the atmosphere around the portion where is installed is replaced with the atmosphere, the correction value Δt of the zero point is calculated when the combustion of the water heater A is not restarted. The time during which the energized state is maintained can be effectively used, which is convenient.

When the combustion of the water heater A is restarted within a short time as described above, the restart of the combustion is detected in STEP13, and the operations in STEP9 and thereafter are performed again. C
O sensor 20 is slight variation in the output characteristics due to a single impact, the first time when the error of FIG. 4 shows and CO concentration determination value C _M the variation is accumulated to the true CO concentration C _N has expanded Since there is a possibility that the detection of incomplete combustion cannot be performed accurately, the incomplete combustion is not immediately erroneously detected by the operations of STEP 13 and subsequent steps. In the water heater A, even if the combustion is restarted several times in a short time as described above, the state in which the combustion is not performed may always reach 30 minutes. Sometimes ST
By correction value Δt of the zero point is calculated in EP15, error between the Figure 4 shows the CO concentration determination value C _M and the true CO concentration C _N is maintained within an acceptable range.

In the above operation, if the combustion is started within 30 minutes after the water heater A is installed in STEP4, the controller 21 stops the 30-minute timer 28 in STEP17 and the incomplete combustion determination means in STEP17. 25
As a result, incomplete combustion is detected (STEP 18).
At this time, since the correction value of the zero point has not yet been calculated immediately after the installation, the incomplete combustion determination means 25 calculates the relational expression (the straight line M shown in FIG. 4) stored and held in the output characteristic storage means 22. The detection of incomplete combustion is performed by using it as it is.

When the combustion of water heater A is stopped without detecting incomplete combustion (STEP 19), STEP 1
By the operations from 1 onward, the correction value Δt of the zero point is calculated in the same manner as when normal combustion is stopped. The output characteristics of the CO sensor 20 often fluctuate greatly due to impact during transportation or when the water heater A is installed.
It is desirable to calculate the zero point correction value by performing the operations in STEPS 3 to 6 without performing combustion as much as possible.

After the combustion of water heater A is stopped,
When the power supply monitoring unit 27 detects in step 11 that the power supply to the water heater A has been stopped, the stop of the combustion is considered to be due to a power failure or an artificial stop of power supply.
At this time, since the energization of the water heater A itself is stopped, the energization of the CO sensor 20 is automatically stopped (STEP 2).
0), the controller 21 enters a state of waiting for power recovery.
When the power is restored (STEP 21), the controller 2
1 is recognized in the same manner as when the power is turned on after the water heater A is installed.
The second and subsequent operations are repeated.

At this time, the CO concentration in the atmosphere around the portion where the CO sensor 20 is installed is high due to the interruption of the energization and the combustion is interrupted. After 30 minutes, the atmosphere is replaced.
Therefore, after it is recognized in STEPs 4 and 5 that the non-combustion state has reached 30 minutes, the CO concentration output detection unit 2
By detecting the CO concentration output of the CO sensor 20 at 9, the CO concentration output with respect to the CO concentration in the atmosphere is detected according to the output characteristic indicated by the straight line M in FIG. The detection of the CO concentration output of the sensor 20 is avoided.

When the power is restored after the power failure or the artificial energization is stopped, and the combustion is started within 30 minutes after the power is restored (STEP 4), a 30-minute timer 28 is executed by the controller 21 in STEP 17. Is stopped, and incomplete combustion is detected by the incomplete combustion determination means 25 (STEP 18). At this time, the EEPROM 32
Since the correction value Δt of the zero point calculated at the time of the previous combustion stop is stored and held, the relational expression indicating the output characteristic of the CO sensor 20 can be temporarily corrected using the correction value Δt of the zero point. Then, a correction relational expression as shown by a straight line N in FIG. 4 is derived. Therefore, the incomplete combustion determination means 25
By comparing the CO concentration determination value calculated from the correction relational expression with the reference value stored in the reference value ROM 24, incomplete combustion can be detected within an allowable error range. Then, the combustion was stopped (STEP 1).
9) After that, the operation after STEP 11 is repeated to calculate the correction value Δt of the zero point again.

In the present embodiment, the calculation of the correction value Δt of the zero point after the combustion of the water heater A is stopped is determined in STEP 10 to STEP 1.
As shown in FIG. 5, the combustion is stopped every 30 minutes after the combustion stops. However, as described above, the CO sensor 20 has a small change in the output characteristics due to one impact. When the fluctuations are accumulated and the error between the CO concentration determination value C _M and the true CO concentration C _N shown in FIG. It is sufficient to calculate the correction value Δt of the zero point before the accumulation, for example, when the non-combustion state reaches 30 minutes ten times, the zero point correction value Δt is calculated once. The calculation of the correction value Δt may be performed.

[0055]

As is apparent from the above, according to the incomplete combustion detecting device of the present invention, when the non-combustion time reaches the predetermined time as described above, the correction value calculating means performs the correction. Since the difference between the CO concentration output with respect to the CO concentration in the atmosphere and the initial set value of the zero point stored in the output characteristic storage means is calculated as a zero point correction value,
The relational expression showing the output characteristic of the O concentration detecting means is CO in the atmosphere.
The concentration is corrected as the zero point, and even if the output characteristics fluctuate, the error between the CO concentration determination value calculated from the CO concentration output of the CO concentration detecting means and the actual CO concentration is reduced, and the error is more accurately determined. Complete combustion can be detected.

In the incomplete combustion detection device according to the present invention, when the combustion device stops burning and the time during which combustion is not performed reaches a predetermined time, the correction value calculating means calculates the correction value of the zero point. By doing so, accumulation of fluctuations in output characteristics due to long-term use can be prevented, and incomplete combustion can be detected more accurately.

Further, in the incomplete combustion detecting device of the present invention,
When the non-combustion time reaches a predetermined time after the combustion device has been energized, the correction value calculation means calculates the correction value of the zero point, thereby enabling the combustion device to operate. It is no longer necessary to distinguish between after installation and after power is turned off and power is restored. By correcting the correction value of the zero point as described above, immediately after the installation, when the combustion is started, the C due to the impact during transportation and at the time of the installation is reduced.
Variations in the output characteristics of the O concentration detection means can be corrected, and incomplete combustion can be detected more accurately. In addition, in the case where power supply is stopped and power is restored, the zero point is not corrected to a high CO concentration due to sudden interruption of combustion, and incomplete combustion is detected more accurately when combustion is restarted. be able to.

Further, in the incomplete combustion detecting apparatus of the present invention, the EEPROM is used as the zero point correction value storage means, so that the previously calculated zero point correction value is stored and held even when the power supply is stopped. Since the power supply is stopped due to an accident such as a power outage or artificially stopped power supply,
When combustion is restarted before the time during which combustion is not performed reaches a predetermined time, a correction relational expression can be calculated using the zero-point correction value stored in the EEPROM, and then combustion starts. Incomplete combustion can be detected more accurately when the operation is performed.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view of a water heater provided with an incomplete combustion detection device according to the present invention.

FIG. 2 is a block diagram showing a configuration example of an incomplete combustion detection device according to the present invention.

FIG. 3 is a flowchart for explaining the operation of the incomplete combustion detection device shown in FIG. 2;

FIG. 4 is a graph illustrating output characteristics of a CO sensor.

FIG. 5 is a block diagram showing a configuration example of a conventional incomplete combustion detection device.

[Description of Signs] 20 ... CO concentration detecting means, 22 ... Output characteristic storing means, 2
3: CO concentration determination value calculation means, 25: incomplete combustion determination means, 26: combustion control means, 30: correction value calculation means, 32
... Correction value storage means, 34. Correction relational expression calculation means, A. Combustion equipment.

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Claims (4)

(57) [Claims] 1. A method for detecting the concentration of CO in exhaust gas from combustion equipment.
O concentration detection means, a relational expression between the CO concentration output of the CO concentration detection means and the actual CO concentration, and a CO concentration output of the CO concentration detection means corresponding to a case where the actual CO concentration is zero in the relational expression. The initial value of the indicated zero point is
An output characteristic storage means for storing as an output characteristic of the O concentration detection means, and a CO used for determination of incomplete combustion from the CO concentration output of the CO concentration detection means and the relational expression stored in the output characteristic storage means. CO concentration determination value calculation means for calculating a concentration determination value; incomplete combustion determination means for comparing the CO concentration determination value with a preset reference value to determine incomplete combustion of the combustion device; An incomplete combustion detection device for a combustion device, comprising: combustion control means for stopping combustion of the combustion device according to the determination of the means. Correction value calculating means for calculating a correction value of the zero point from a difference between the CO concentration output of the means and the initial set value of the zero point stored in the output characteristic storing means; and a zero value calculated by the correction value calculating means. (B) a correction value storage means for storing a correction value for the point; and a correction relational expression calculated from the correction value for the zero point stored in the correction value storage means and the relational expression stored in the output characteristic storage means. Means for calculating a CO concentration determination value, wherein the CO concentration determination value calculation means calculates a CO concentration determination value from the CO concentration output of the CO concentration detection means and the correction relational expression calculated by the correction relation expression calculation means. An incomplete combustion detection device for a combustion device. 2. The correction value calculating means calculates the correction value of the zero point when a time period during which the combustion device stops burning after stopping combustion reaches a predetermined time. Item 2. The incomplete combustion detection device for a combustion device according to Item 1. 3. The correction value calculating means calculates the correction value of the zero point when a time during which the combustion device has not been burning after the energization of the combustion device has reached a predetermined time. The apparatus for detecting incomplete combustion of a combustion apparatus according to claim 1. 4. The incomplete combustion detection device for a combustion apparatus according to claim 1, wherein said correction value storage means is a readable and writable nonvolatile storage means (EEPROM).