JPH0814557A - Combustion instrument - Google Patents

Abstract

PURPOSE:To provide a combustion instrument, capable of grasping the deterioration of a CO sensor surely and simply whereby capable of effecting a proper treatment. CONSTITUTION:An abnormality treating means 26, judging that the deterioration of a CO sensor 14 is advanced when the level of signal of the CO sensor 14 for detecting the concentration of CO is continued for a predetermined period of time, then, has become lower than a predetermined lower limit level and effecting combustion prohibiting treatment or alarm generating treatment through an indicator 20, is provided. The lower limit level is set so as to be a value smaller than the signal level under stationary condition by a predetermined amount with respect to a reference value or the signal level of a stationary condition, which is outputted when a gas burner is not being operated or upon normal combustion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion device equipped with a CO sensor.

[0002]

2. Description of the Related Art For example, in a water heater, C is provided in the exhaust passage.
An O sensor is provided to detect the concentration of CO gas generated by incomplete combustion or the like during the combustion operation of the burner from the signal of the CO sensor output at a level corresponding to it, and the signal level of the CO sensor is set to a predetermined reference level. It is known that the combustion operation is stopped when the CO concentration exceeds a value, that is, when the generated CO concentration exceeds a predetermined reference concentration.

In this type of combustion equipment, in order to accurately stop the combustion operation according to the generation of CO gas, C
It is premised that the signal level of the O sensor corresponds to the actually generated CO concentration, but according to various studies made by the present inventors, the CO sensor shows that the CO sensor may change over time due to adhesion of oil or the like. Gradually deteriorates. Then, when such deterioration progresses, even if the CO sensor itself has not failed,
Even if the actual CO concentration is the same, the signal level of the CO sensor becomes smaller than that at the initial stage. Therefore, in the state where the deterioration of the CO sensor progresses in this way, the signal level of the CO sensor does not exceed the reference value for stopping the combustion operation, even if the actually generated CO concentration exceeds the predetermined reference concentration. In such a case, there is a disadvantage that the combustion operation continues even though the CO concentration is higher than the reference concentration.

On the other hand, in this type of combustion equipment, as disclosed in, for example, Japanese Utility Model Laid-Open No. 63-49166, C
It is known that the presence or absence of a failure in the O sensor is grasped, and when a failure in the CO sensor occurs, abnormal processing such as prohibition of combustion operation is performed. In the device disclosed in the same publication, the signal level of the CO sensor in a normal state is temporarily changed due to a miscellaneous gas such as water adhering to the CO sensor at the initial stage of energization when the combustion operation is stopped. Utilizing the property of rising, then falling to a stable level,
Only when the signal level of the CO sensor is kept above the predetermined reference level for a certain period of time at the initial stage of energization to the CO sensor, and after the certain period of time, the signal level becomes below the predetermined reference level, the CO sensor becomes normal. In other cases, it is determined that the CO sensor has failed,
Abnormal processing such as prohibition of combustion operation is performed. Further, in the publication of the same publication, the fact that CO gas is generated to some extent at the time of ignition of the burner is used, and when the signal level of the CO sensor does not exceed a predetermined reference level at the time of ignition, the CO sensor fails. In addition, abnormal processing such as prohibition of combustion operation is performed.

Therefore, in order to solve the above-mentioned inconvenience when the deterioration of the CO sensor progresses, as seen in the above publication, the CO sensor is charged at the initial stage of energization of the CO sensor and at the time of ignition of the burner. By comparing the signal level of the sensor with an appropriate reference level, it may be possible to grasp the presence or absence of deterioration of the CO sensor and perform abnormal processing such as prohibiting combustion operation when the deterioration of the CO sensor is progressing. To be

[0006] However, such a device has the following disadvantages.

That is, in the initial stage of energization of the CO sensor, the extent to which the signal level rises is not always the same due to the degree of adhesion of foreign gas such as moisture even if there is no deterioration or failure of the CO sensor, and it is unstable. Easy to become
Therefore, even when a constant reference level for determining the presence or absence of deterioration of the CO sensor is set at the initial stage of energization of the CO sensor, the CO sensor will exceed the reference level despite the progress of deterioration of the CO sensor. In some cases, CO
It is difficult to ascertain whether or not the sensor has deteriorated.

Further, the concentration of CO gas generated at the time of ignition tends to vary depending on various environmental conditions. Therefore, as in the case of the initial stage of energization, even when the constant reference level for determining the presence / absence of deterioration of the CO sensor is set when the burner is ignited, the deterioration of the CO sensor is progressing even if the CO sensor is deteriorated. In some cases, the reference level may be exceeded, and it is difficult to reliably grasp the presence or absence of deterioration of the CO sensor.

[0009]

DISCLOSURE OF THE INVENTION The present invention aims to improve such a combustion device, and more specifically, it is possible to reliably and easily grasp the deterioration of the CO sensor, and to carry out an appropriate treatment by the deterioration. It is an object of the present invention to provide a combustion device that can be used.

[0010]

In order to achieve such an object, the present invention provides a CO sensor which outputs a signal of a level according to the CO concentration generated during the operation of a combustion section, and a predetermined output of the CO sensor. When the output of the CO sensor is equal to or lower than a preset lower limit value in a combustion device including an operation control unit that stops the operation of the combustion unit when the output exceeds a reference level, a predetermined abnormality occurs. The lower limit value is a signal in the steady state based on a signal level in the steady state output by the CO sensor in the normal state when the combustion unit is not operating or in the normal combustion. It is characterized in that it is set to a value smaller than the level by a predetermined amount.

Further, the abnormality processing means performs the predetermined abnormality processing when the output of the CO sensor continues for a predetermined time and becomes equal to or less than the lower limit value.

Further, the abnormality processing means, when the output of the CO sensor falls below the predetermined lower limit value, the C
A means for temporarily raising the temperature of the O sensor and heating it is provided.
The predetermined abnormality process is performed when the output of the CO sensor again becomes equal to or lower than the predetermined lower limit value after the temperature rise / heating of the sensor.

In this case, the abnormality processing means is the CO
The predetermined abnormality process is performed when the output of the CO sensor is equal to or lower than the lower limit value for a predetermined period of time after the temperature rise / heating of the sensor.

Further, the abnormality processing by the abnormality processing means includes a processing for prohibiting the operation of the combustion section.

Further, the abnormality processing by the abnormality processing means includes alarm generation processing.

[0016]

According to the present invention, when the CO sensor deteriorates due to the adhesion of oil or the like, and the signal level of the CO sensor lowers from the initial signal level and falls below the lower limit value, the abnormality processing means determines a predetermined value. Abnormality processing is performed. At this time, the lower limit is a predetermined amount with respect to the signal level in the steady state based on the signal level in the steady state output from the CO sensor in the normal state when the combustion unit is not operating or during normal combustion. Since it is set to a small value, when the deterioration of the CO sensor progresses, the signal level of the CO sensor surely drops below the lower limit value at least in the steady state when the combustion unit is not in operation or during normal combustion. And, therefore,
It is possible to reliably grasp the progress of deterioration of the CO sensor. Then, since the abnormality processing is performed according to the grasped information, it is possible to appropriately perform appropriate processing for deterioration of the CO sensor.

When the predetermined abnormality processing is performed when the output of the CO sensor is below the lower limit value for a predetermined period of time, the signal level of the CO sensor is temporarily lowered due to noise or the like. A situation in which abnormal processing is performed can be avoided, and it becomes possible to more reliably and accurately perform the grasp of the progress of deterioration of the CO sensor and the processing corresponding thereto.

Also, for example, when the combustion amount in the combustion section is relatively low, water vapor is likely to be generated, and this water vapor may condense on the CO sensor. Then, in such a case, the output of the CO sensor may decrease as in the case of deterioration of the CO sensor, and may be continuously below the lower limit value. In such a case, the abnormality processing may be performed as in the case of deterioration of the CO sensor.
In this case, if the water vapor condensed on the CO sensor is removed, the output of the CO sensor returns to normal, and normal combustion operation or the like can be performed without any trouble.

Therefore, when the output of the CO sensor falls below the lower limit value, the temperature of the CO sensor is temporarily raised.
When the CO sensor is heated and thereafter the output of the CO sensor becomes equal to or lower than the lower limit value again, the predetermined abnormality process is performed. By doing so, when the output of the CO sensor falls below the lower limit value due to the condensation of the steam on the CO sensor, the CO sensor is temporarily heated and heated to remove the condensed steam. It Therefore, unless continuous deterioration of the CO sensor occurs, the output of the CO sensor exceeds the lower limit value, and the abnormality processing by the abnormality processing means is not performed. If the CO sensor is deteriorated, the deteriorated state cannot be eliminated even by raising or heating the CO sensor. Therefore, the output of the CO sensor becomes equal to or lower than the lower limit value, and the abnormality processing by the abnormality processing means is performed. Done.

Temporary temperature rise of the CO sensor as described above
When heating is performed, generally, the output of the CO sensor immediately after that is likely to cause a temporary decrease in output even if the CO sensor is normal, and may temporarily fall below the lower limit value. Therefore, the abnormality processing after the temperature increase / heating of the CO sensor is performed when the output of the CO sensor after the temperature increase / heating continues for a predetermined time and is below the lower limit value. By doing so, when the CO sensor returns to normal due to the temperature rise / heating of the CO sensor, the abnormality processing by the abnormality processing means is not reliably performed.

When the abnormality processing by the abnormality processing means includes processing for prohibiting the operation of the combustion section, CO
A situation in which the combustion equipment is used in a state where the CO concentration cannot be detected correctly due to deterioration of the sensor is avoided.

Further, when the abnormality processing by the abnormality processing means includes an alarm generation processing, it is possible to notify the user of the progress of deterioration of the CO sensor and prompt replacement of the CO sensor or repair. .

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the present invention will be described with reference to FIGS. FIG. 1 is a system configuration diagram of a water heater as a combustion device of the present embodiment, FIG. 2 is a block configuration diagram of essential parts of the water heater of FIG. 1, and FIG. 3 is a flowchart for explaining the operation of the water heater of FIG. 4 is a diagram showing the output of the CO sensor used in the water heater of FIG.

Referring to FIG. 1, 1 is a water heater main body, 2 is a water pipe provided through a heat exchanger 3 provided in the water heater main body 1, and 4 is an upstream side of the heat exchanger 3. A water amount sensor provided in the water flow pipe 2, 5 is a hot water outlet temperature sensor provided in the water flow pipe 2 on the downstream side of the heat exchanger 3, and 6 is a fuel gas in a gas burner 7 (combustion section) provided in the water heater main body 1. A gas supply pipe for supplying the gas, reference numerals 8, 9, 10 respectively supply an original solenoid valve, a main solenoid valve and a gas proportional valve, which are sequentially provided in the gas supply pipe 6 from the upstream side, and 11 supplies combustion air to the gas burner 7. Combustion fan, 12 is an igniter that ignites the gas burner 7,
13 is a frame rod for detecting ignition of the gas burner 7,
14 is a CO sensor attached to the water heater main body 1 in the vicinity of the exhaust port 15 of the water heater main body 1, 16 is a controller for controlling the operation of the water heater, and 17 is used by the user to set the hot water temperature. It is an operation unit for.

In this case, the controller 16 is composed of an electronic circuit including a microcomputer,
By connecting this to a commercial power source (not shown) through a power plug, power is supplied and activated. At this time, the controller 1
6 is a heater built in the CO sensor 14 (not shown)
To energize. Then, the CO sensor 14 outputs a signal of a level corresponding to the concentration of CO gas generated during the combustion operation of the gas burner 7 in a steady state where the heater is heated to about 200 ° C.

Further, the operation unit 17 is provided with a temperature setting switch 18 for the user to set the hot water temperature, an operation switch 19, a display 20 for displaying an error and the like. Here, in this embodiment, the operation switch 19 is a non-locking type, and the operation switch 19 is
Every time the button is pressed, the operation mode and the operation stop mode of the water heater are alternately switched.

Referring to FIG. 2, the controller 16
The main functional components thereof are an energization control unit 21 that controls energization of the CO sensor 14, a CO monitoring unit 22 that monitors the output of the CO sensor 14, a hot water temperature sensor 5, a water amount sensor 4, and a frame rod. The igniter 12, the original solenoid valve 8, the main solenoid valve 9, the gas proportional valve 1 in accordance with the detection signal of 13, the instruction signal from the CO monitoring unit 22 and the operation unit 17, and the like.
0, the operation control unit 23 for controlling the combustion fan 11, and the CO
The display unit 20 of the operation unit 17 is provided with a display command unit 24 for displaying an error or the like in response to an instruction signal or the like from the monitoring unit 22. Here, according to the configuration of the present invention, the CO monitoring unit 22 and the operation control unit 23 configure the operation control unit 25, and the CO monitoring unit 22, the operation control unit 23, and the display command unit 24.
The display 20 constitutes an abnormality processing means 26.

Next, the operation of the water heater of this embodiment will be described.

Referring to FIGS. 1 to 3, the controller 1
6 is fed, the energization control unit 21 causes the CO sensor 1
Energization of the heater (not shown) of No. 4 is started to excite the CO sensor 14 (STEP 1). At this time, the energization control unit 21 starts the timer T1 (see FIG. 2) included in the energization control unit 21, and during the time until the timer T1 times out (20 seconds in this embodiment), the CO sensor 1
4 self-cleaning (STEP2a ~ 2
c). The self-cleaning is a process for positively removing the miscellaneous gas and the like adhering to the CO sensor 14 at the initial stage of energization, and for example, the heater of the CO sensor 14 is heated so as to heat the CO sensor 14 to about 400 ° C. It is done by energizing the. Then, the energization control unit 21 performs the self-cleaning as described above, and then the heater for maintaining the heating temperature of the CO sensor 14 at about 200 ° C. in order to detect the CO concentration by the CO sensor 14. Reduce the amount of electricity supplied to.

When the CO sensor 14 is energized as described above, the CO sensor 14 in its new state is
In a normal atmosphere, for example, a signal of the level shown by the solid line in FIG. 4 is output, and the steady state (heating temperature of 200 ° C.
(State held at), the signal level converges to a constant signal level L1. In the present embodiment, the signal level L1 in such a steady state is preset as the offset value of the CO sensor 14.

Note that the CO sensor 14 can eliminate miscellaneous gas such as water by the self-cleaning, but if oil or the like adheres, the CO sensor 14 deteriorates, and as shown by a phantom line in FIG. , The signal level L becomes smaller than in the initial normal case.

When the above self-cleaning is completed,
When the 20-second timer starts and the 20-second timer times out (STEP 3, 4), the controller 1
The CO monitoring unit 22 of 6 starts reading the signal level L of the CO sensor 14 (STEP 5), and compares the signal level L with a predetermined lower limit level L2 (STEP 6). Here, the lower limit level L2 is a level for determining whether or not the CO sensor 14 is deteriorated, and as shown in FIG. 4, the CO sensor 14 is normally operated when the gas burner 7 is not operating (when combustion is stopped). With reference to the signal level L1, it is set to a level slightly lower than the level L1 by a predetermined level. When the CO sensor 14 has deteriorated to some extent, the signal level L (the signal level L after STEP 4) of the CO sensor 14 in the steady state (constantly stable state) is lower than the lower limit level L2. Get smaller.

In the comparison of STEP 6, CO sensor 1
4 is larger than the lower limit level L2 (NO in STEP 6), that is, when the deterioration of the CO sensor 14 has not progressed, a timer T described later is used.
After 2 is reset, the operation control unit 23 of the controller 16 determines whether or not the operation switch 19 of the operation unit 17 has been pressed (STEP 7).
It is determined whether the value of the flag F is "1" or "0" (STEP 8a, 8b). Here, the flag F indicates whether the current operating state of the water heater of the present embodiment is the operating mode or the non-operating mode, and F = 0 is set in the initial non-operating mode. ing. Therefore, for example, when the operation switch 19 is pressed in the non-operation mode, at this time, F = 0 (NO in STEP8a), and in this case, the operation control unit 23 causes the gas burner 7 to perform ignition processing (STEP9). After that, the flag F is set to "1" (STEP 10), and the combustion control of the gas burner 7 is further performed (STEP 11).

In this case, referring to FIG. 1, in the ignition process, the source solenoid valve 8 and the main solenoid valve 9 are opened to supply the fuel gas to the gas burner 7 and to combust the fan 1.
0 is driven, and the igniter 12 is driven in this state to ignite the gas burner 7.

Further, in the combustion control, while detecting the outlet temperature and the amount of water flowing through the water pipe 2 through the heat exchanger 3 during the combustion of the gas burner 7 through the outlet temperature sensor 5 and the water amount sensor 4, respectively, The opening amount of the gas proportional valve 10 and the rotation speed of the combustion fan 11 are controlled so that the hot water temperature matches the set temperature set by the temperature setting switch 18 of the operation unit 17, and the combustion amount of the gas burner 7 is controlled. It is done by that.

When the combustion control of the gas burner 7 is started in this way, the CO monitoring unit 22 of the controller 16 sets the signal level L of the CO sensor 14 indicating the concentration of CO gas generated during the operation of the gas burner 7 to a predetermined reference level (see FIG. (See 4)
(STEP 12). In this comparison, when the signal level L of the CO sensor 14 is lower than the reference level (NO in STEP 12), in other words, when the gas burner 7 is normally burning,
Returning to the comparison of STEP6, basically the following ST
The combustion control in EP11 and the signal level of the CO sensor 14 in STEPs 6 and 12 are continuously monitored. When the operation switch 19 is pressed again during such an operation (YES in STEP 7), the flag F = 1 at this time (Y in STEP 8a).
ES), after the flag F is cleared to "0" (STEP 13), the operation control unit 23 of the controller 16 stops the combustion operation of the gas burner 7 (STEP 14). When the combustion operation is stopped, the original solenoid valve 8 and the main solenoid valve 9 are closed to cut off the gas supply to the gas burner 7, and
This is performed by stopping the combustion fan 11.

Further, the CO sensor 14 in STEP 6
The monitoring of the signal level of 1 continues even after the combustion operation is stopped as long as the CO sensor 14 is energized.

In this embodiment, the controller 1
Although the CO sensor 14 is always energized in the state where 6 is connected to the power source, the CO sensor 14 may be energized only during operation. In this case, the self-cleaning may be performed every time the operation is started, but this makes it possible to quickly supply hot water when intermittent hot water supply is required at short time intervals such as in a shower. Therefore, the CO sensor 14 continues to be energized for a certain period of time (for example, 30 minutes) even after the operation is stopped, and if the operation is restarted during that time, the CO sensor 14 is immediately stopped without performing self-cleaning. Monitor the output of
It is preferable to restart the combustion operation promptly.

The operation described above is an operation in the case where the CO sensor 14 is normal and the combustion operation of the gas burner 7 is normally performed without causing incomplete combustion, for example, during the combustion of the gas burner 7. When incomplete combustion occurs and CO gas is generated and the CO concentration increases, the signal level of the CO sensor 14 indicating the CO concentration becomes equal to or higher than the reference level (YES in STEP 12), and in this case, the controller 16 In response to the instruction to the CO monitoring unit 22, the operation control unit 23 stops the combustion operation of the gas burner 7 in the same manner as in the above case (STEP 14) (STEP 15). Further, in this case, the display command unit 24 of the controller 16 causes the display 20 of the operation unit 17 to display an error display indicating that the incomplete combustion has occurred in response to the instruction from the CO monitoring unit 22 ( STEP 16), and let the user recognize it.

When the CO sensor 14 deteriorates due to the adhesion of oil or the like and the deterioration progresses to some extent, the CO sensor 1
The signal level L of 4 is equal to or lower than the lower limit level L2 in a non-operating state or in a continuous normal combustion operating state in which CO gas generation is sufficiently small, and in this case, the CO monitoring unit 22 of the controller 16 , Start timer T2 (see FIG. 2) included therein (STEP
17, 18).

Then, when the signal level L of the CO sensor 14 does not exceed the lower limit level L2 within the time (20 seconds in this embodiment) until the timer T2 times out, that is, the condition of L≤L2 is 20 seconds. If you continue (S
If YES in TEP19, the CO monitoring unit 22 instructs the operation control unit 23 to prohibit combustion operation (ST.
EP20), and further instructs the display command unit 24 to cause the display device 20 to perform a predetermined display. In this case, when the combustion operation of the gas burner 7 is being performed, the operation control unit 23 stops the combustion operation as in STEP 14, and then takes the action of prohibiting the subsequent operation to perform the combustion inhibition process. Be seen. In addition, the display command unit 24 uses the CO sensor 1
4 is displayed on the display unit 20 (STEP 21), and an alarm generation process is performed to make the user recognize that the CO sensor 14 needs to be replaced.

Before the timer T2 times out, the signal level L of the CO sensor 14 is set to the lower limit level L.
When it exceeds 2 again (N in STEP 6
O), the timer T2 is reset (STEP 22) without performing abnormal processing such as prohibiting the combustion operation, and the above-described normal operation is performed.

During the combustion operation of the gas burner 7,
In the case of misfiring or misfiring, this is detected by the controller 16 via the frame rod 13, and in this case, the controller 16 determines STEP1.
The same processing as 5 and 16 is performed.

As described above, in the apparatus of this embodiment, C
When the deterioration of the O sensor 14 progresses to some extent and the CO concentration cannot be accurately detected, the gas burner 7
Since the combustion operation of No. 2 is prohibited and the alarm is issued by the display 20, it is possible to avoid the situation where the combustion operation of the gas burner 7 is repeated in a state where the CO concentration cannot be accurately detected. In this case, the lower limit level L2 for determining the deterioration of the CO sensor 14 is
Normal signal level L of the CO sensor 14 in the steady state
Since the level is set to a level slightly smaller than the level L1 by a predetermined level with reference to 1, the CO sensor 14
If the deterioration of CO is advanced to some extent, at least in a non-operating state in which the signal level L of the CO sensor 14 stabilizes at a substantially constant level, or in a continuous and normal combustion operating state in which CO gas generation is sufficiently small, Certainly CO sensor 1
The signal level L of No. 4 becomes lower than the lower limit level L2, so that the deterioration of the CO sensor 14 can be surely grasped. Further, when the signal level L of the CO sensor 14 continues to fall below the lower limit level L2 for a fixed time (20 seconds),
Since it is determined that the CO sensor 14 has deteriorated, it is possible to exclude a case where the signal level L is temporarily reduced due to noise or the like, and it is possible to accurately grasp the deterioration of the CO sensor 14. Further, even when the CO sensor 14 fails and no signal is output, the signal level L of the CO sensor 14 is continuously lower than the lower limit level L2. Is performed, and the situation in which the combustion operation of the gas burner 7 is performed in such a failure state is avoided.

Next, another example of the present invention will be described with reference to FIGS. FIG. 5 is a flow chart for explaining the operation of the water heater which is the combustion device of this embodiment, and FIG. 6 is a diagram showing the output of the CO sensor in this embodiment.

The present embodiment (water heater) has the same structure as that of the above-mentioned embodiment but is different only in the operation. Therefore, the reference numerals shown in FIGS. The same reference numerals are used to omit the description of the configuration of the water heater of this embodiment, and only the operation will be described.

Also in the operation of this embodiment, the same steps as those in FIG. 3 are designated by the same step numbers, and detailed description thereof will be omitted.

With reference to FIG. 5, in the water heater of the present embodiment, self-cleaning or the like is performed after the start of energization of the CO sensor 14, just as in the case of the above-described embodiment (see FIG. 3). (See STEPS 1 to 4), and then the CO monitoring unit 22 of the controller 16 starts reading the signal level L of the CO sensor 14 (STEP 5).

In this way, the signal level L of the CO sensor 14 is
When the reading of is started, the CO monitoring unit 22 of the controller 16 sequentially determines whether or not the values of the predetermined flags Fa and Fb are set to "1" (STEP2
2, 23) and the signal level L of the CO sensor 14 is compared with the lower limit level L2 (see FIG. 6) (STEP 24).
The flag Fa is a flag indicating whether or not self-cleaning, which will be described later, is performed, and the flag Fb is a flag for grasping whether or not the state is immediately after the self-cleaning. Each is set to "0".

In the comparison of STEP24, when L> L2, that is, when the CO sensor 14 is normal (NO in STEP24), the controller 16 causes STEP7 to STE to be the same as in the above-described embodiment.
The process of P16 is performed. That is, the start and stop of the operation according to the operation of the operation switch 19, the ignition process, the combustion control, the C
The operation such as the stop of the operation is performed according to the signal level L of the O sensor 14.

On the other hand, in the comparison of STEP24, L ≦
When L2, that is, when the signal level L of the CO sensor 14 is lower than the signal level L1 when it is normal by a predetermined amount or more (YES in STEP 24), the controller 16 causes the timer of the energization control unit 21 to operate. T1
(20 seconds timer) is started, and the flag F
The value of "a" is set to "1" (STEP 25, 26), and the energization control unit 2 continues until the timer T1 times out.
In step 1, the CO sensor 14 is self-cleaned (STEP 27, 28 and STEP 22). This self-cleaning is basically the same process as the self-cleaning of the CO sensor 14 immediately after the start of energization, and the energization control unit 21 sends a heater (not shown) to the CO sensor 14 within the time period of the timer T1. This is performed by increasing the amount of energization and raising / heating the CO sensor 14 to, for example, about 400 ° C. After the temperature of the CO sensor 14 is raised and heated, the energization control unit 21 cools the CO sensor 14 to the original heating temperature (200 ° C.) for detecting the CO concentration and keeps the temperature. Energize the heater.

When the CO sensor 14 is heated / heated in this manner, for example, water vapor is condensed on the CO sensor 14, so that the CO sensor 14 is deteriorated.
When the signal level L of the sensor 14 falls below the lower limit level L2, the water vapor condensed on the CO sensor 14 evaporates, so that the CO sensor 14 can detect the CO concentration normally. However, when the CO sensor 14 is deteriorated, the deterioration state is not resolved.

When the CO sensor 14 is heated / heated by performing the above-mentioned self-cleaning, C
The signal level L of the O sensor 14 increases as shown by the portion indicated by reference numeral A in FIG. 6, and thereafter, the energization control unit 21 decreases the energization amount to reduce the temperature to the original heating temperature (200 ° C.). The CO sensor 14 signal level L
Will fall. Then, when the CO sensor 14 is normal (including the case where the condensed water vapor is removed), it finally returns to the steady state level L1. in this case,
When the signal level L of the CO sensor 14 is lowered, as shown in the part indicated by reference numeral B in FIG.
The output level L of the sensor 14 is likely to be temporarily excessively decreased, and finally falls back to the steady-state level L1 after being decreased below the level L1 and the lower limit level L2. However, when the deterioration of the CO sensor 14 is progressing, C
The output level L of the O sensor 14 is continuously the lower limit level L2.
It drops below.

During the self-cleaning as described above, the CO concentration cannot be correctly detected, so the controller 16 does not make the determination in STEP 12 for monitoring the CO concentration. That is, in this embodiment, a STEP 12a for judging the value of the flag Fa is provided between STEPs 11 and 12 in FIG.
During the above self-cleaning, Fa = 1, so C
The determination of STEP 12 comparing the signal level L of the O sensor 14 with the reference level (see FIG. 6) is not performed.

When the above self-cleaning is completed (YES in STEP 28), the controller 16 then controls the timer T2 (20-second timer) of the CO monitoring unit 22.
Is started (STEP 29), the flag Fa is cleared to "0", and the flag Fb is set to "1" (STEP 30). The energization control unit 21 of the controller 16 controls the heating temperature of the CO sensor 14 to increase.
The CO sensor 14 is energized so as to return to the original temperature (200 ° C.) before heating.

At this time, in STEP 23 of FIG. 5, Y
As a result, the controller 16 causes the CO monitor 22 to change the signal level L of the CO sensor 14 to the lower limit level L.
2 (STEP 31).

If L> L2 in this comparison (NO in STEP 31), C of the controller 16
The O monitoring unit 22 monitors whether or not the state of L> L2 is maintained until the timer T2 expires while confirming the value of a flag Fc described later (STEP 32). That is, after the self-cleaning of the CO sensor 14, the signal level L of the CO sensor 14 is changed to the lower limit level L.
If maintained above 2, then STE
When the process of P23, 31, and 33 is repeated and the timer T2 times out in this state (YES in STEP33), the controller 16 clears the values of the flags Fb and Fc to "0" (STEP34), and then the STE.
Normal processing from P23 (processing such as STEP 9 and 11) is performed.

On the other hand, after the self-cleaning of the CO sensor 14, the signal level L of the CO sensor 14 becomes the lower limit level L.
When it becomes 2 or less (YE in STEP23
S), after confirming the value of the flag Fc described later (STEP3
5) restart the timer T2 (STEP3
6) Further, the value of the flag Fc is set to "1" (STEP 37). This flag Fc indicates the CO sensor 14
After self-cleaning, the CO sensor 14 is set to "1" when the signal level L falls below the lower limit level L2, and is normally cleared to "0".

The CO monitoring unit 2 of the controller 16
2 indicates that the signal level L of the CO sensor 14 is the lower limit level L2.
When the following state is continuously maintained until the timer T2 restarted as described above is timed up (YES in STEP 38), that is, C
When the O sensor 14 has deteriorated due to self-cleaning, the operation control unit 23 is instructed to prohibit combustion operation (STEP 39), and a predetermined display is displayed on the display command unit 24. Instruct machine 20 to do so. At this time, the operation control unit 23
As in the case of the above-described embodiment, when the gas burner 7 is in the combustion operation, after the combustion operation is stopped, the subsequent operation is prohibited and the combustion prohibition process is performed. The display command unit 24 also causes the display device 20 to perform a predetermined display indicating deterioration of the CO sensor 14 (STEP 4
0), whereby alarm generation processing is performed to make the user recognize the necessity of replacing the CO sensor 14.

Further, the CO monitoring section 22 of the controller 16
Even if the signal level L of the CO sensor 14 once falls below the lower limit level L2 after self-cleaning, the signal level L becomes higher than the lower limit level L2 before the timer T2 restarted at that time expires. In the case (NO in STEP 31 and YES in STEP 32), that is, although the CO sensor 14 returns to the normal state by self-cleaning as described above, the temperature of the CO sensor 14 after the self-cleaning causes the CO sensor 14 to cool down temporarily, If the signal level L of 14 has dropped below the lower limit level L2 (see FIG. 6), the STE
In P34, the values of the flags Fb and Fc are cleared to "0". Then, after that, the controller 16 performs the normal process from STEP 23 (the process of STEP 9, 11, etc.).

As described above, according to this embodiment, as in the case of the above-described embodiments, the deterioration of the CO sensor 14 progresses and C
When the O concentration cannot be detected accurately,
The combustion operation of the gas burner 7 is prohibited, and the display 20
Since the alarm is generated by, the situation in which the combustion operation of the gas burner 7 is repeated in a state where the CO concentration cannot be accurately detected is avoided.

Whether or not the CO sensor 14 is deteriorated is determined once when the signal level L of the CO sensor 14 falls below the lower limit level L2, the CO sensor 14 is once heated / heated (self-cleaning). Then, after that, it is performed by monitoring whether or not the signal level L of the CO sensor 14 is continuously maintained at the lower limit level L2 or less.
For example, when the water vapor is condensed on the O sensor 14, the CO sensor 1
In the case where the output of the CO sensor 14 is reduced by the temperature rise / heating of No. 4, the signal level L of the CO sensor 14 is returned to the lower limit level L2 or more, and the combustion operation of the gas burner 7 is hindered. You can continue without.

Moreover, after the temperature of the CO sensor 14 is raised and heated, the timer time of the timer T2 (20 seconds) is continued and C
Only when the signal level L of the O sensor 14 is maintained below the lower limit level L2, abnormal processing such as operation prohibition processing and alarm generation processing is performed. Therefore, in the case of deterioration of the CO sensor 14, the abnormal processing is performed. When the output of the CO sensor 14 decreases due to dew condensation of water vapor or the like, the signal level L of the CO sensor 14 is decreased by the temperature decrease after the CO sensor 14 is returned to the normal state by the temperature increase / heating.
Is temporarily lowered to the lower limit level L2 or lower, normal operation can be continued without performing abnormal processing. Therefore, when the CO sensor 14 returns to the normal state due to the temperature rise / heating of the CO sensor 14, it is possible to surely continue the normal operation, and to improve the usability of the water heater. can do.

In the present embodiment, when the signal level L of the CO sensor 14 is maintained at the lower limit level L2 or less after the temperature increase / heating of the CO sensor 14 continues for the timer time of the timer T2 (20 seconds). Although the abnormal processing such as the operation prohibition processing and the alarm generation processing is performed, the lower limit level L2 is compared in consideration of the temporary output decrease of the CO sensor 14 due to the temperature increase of the CO sensor 14 and the temperature decrease after the heating. If the temperature is set to be relatively low, the abnormality processing may be performed when the signal level L of the CO sensor 14 falls below the lower limit level L2 after the temperature rise / heating of the CO sensor 14.

In each of the embodiments described above,
An alarm generation process in case of deterioration of the CO sensor 14 is displayed on the display unit 2.
Although the display is made to be 0, an alarm may be issued by a buzzer or the like.

Further, in each of the above-described embodiments, C in a normal atmospheric atmosphere in which the gas burner 7 is not combusted is used.
Although the lower limit level L2 is set based on the signal level L1 in the steady state of the O sensor 14, the steady state of the CO sensor 14 in the normal combustion operation state (for example, normal weak combustion state) in which the generation of CO gas is sufficiently small. The lower limit level may be set with reference to such signal level.

In each of the above embodiments, the combustion operation is stopped when the signal level of the CO sensor 14 exceeds a predetermined reference level during combustion of the gas burner 7. However, the signal level of the CO sensor 14 remains unchanged. The combustion operation may be stopped when the temperature reaches a predetermined reference level or higher for a certain period of time. In this case, the CO sensor 14
May be the same time as the above-mentioned fixed time that is measured when the output of the CO sensor 14 is above the reference level and the timer time of the timer T2 that is measured when the output of the CO sensor 14 is below the lower limit value. In this case, the timer T2 Can be shared.

In each of the above embodiments, the CO sensor 14
Although the reading of the signal level L of the CO sensor 14 is started after a lapse of a predetermined time (20 seconds) after the end of self-cleaning immediately after the start of energization to the CO sensor 14, the CO sensor 14 is immediately read after the end of self-cleaning. Signal level L
May be started to be read.

Further, in each of the above-mentioned embodiments, the water heater has been described as an example, but it goes without saying that the present invention can be applied to other combustion equipment such as a fan heater.

[0070]

As is apparent from the above description, according to the present invention, when the output of the CO sensor becomes equal to or lower than the predetermined lower limit value set in advance, predetermined abnormality processing is performed,
The lower limit value is set to a value smaller than the signal level in the steady state by a predetermined amount with reference to the signal level in the steady state output by the CO sensor in the normal state when the combustion unit is not operating or in normal combustion. By doing so, the deterioration of the CO sensor can be grasped surely and easily, and the abnormality processing can be appropriately performed in accordance therewith. And
A situation in which the signal level of the CO sensor is temporarily lowered due to noise or the like and the abnormality processing is performed by performing the abnormality processing when the output of the CO sensor continues to fall below the lower limit value for a predetermined time. C can be avoided
The progress of the deterioration of the O sensor and the corresponding abnormality processing can be performed more reliably and accurately.

When the output of the CO sensor falls below the lower limit value, the CO sensor is temporarily heated and heated, and when the output of the CO sensor falls below the lower limit value again, the abnormal condition In the case of deterioration in which the output reduction of the CO sensor cannot be eliminated by performing the processing, it is possible to perform the abnormal processing according to the deterioration, but in the case of the output reduction of the CO sensor due to the dew condensation of water vapor on the CO sensor. In the case where the CO sensor is returned to the normal state due to the temperature rise / heating of the CO sensor, the CO sensor can be returned to the normal state without performing the abnormal processing, and the normal operation can be performed. The abnormal operation can be performed under necessary and appropriate conditions while performing the normal operation with as little trouble as possible.

In this case, when the output of the CO sensor continues to fall below the lower limit value for a predetermined time after the temperature rise / heating of the CO sensor, the abnormality processing is performed so that the CO sensor rises in temperature. -When the normal state is restored by heating, normal operation can be performed without performing any abnormal processing, and when the CO sensor does not return to the normal state by the temperature rise or heating, Can reliably perform the abnormality processing according to the above.

Further, since the abnormal process includes a process for prohibiting the operation of the combustion unit, the operation of the combustion unit is performed in a state where the CO concentration is not accurately detected by the CO sensor. It is possible to avoid the situation, and it is possible to appropriately perform appropriate abnormality processing according to the deterioration of the CO sensor.

Further, by including the alarm generation process as the abnormal process, it is possible to allow the user to accurately recognize the progress of the deterioration of the CO sensor.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a water heater which is an example of a combustion device of the present invention.

FIG. 2 is a block configuration diagram of a main part of the water heater of FIG.

3 is a flowchart for explaining the operation of the water heater of FIG.

FIG. 4 is a diagram showing signals of a CO sensor used in the water heater of FIG. 1.

FIG. 5 is a flowchart for explaining the operation of a water heater which is another example of the combustion device of the present invention.

FIG. 6 is a diagram showing a signal of a CO sensor for explaining the operation of another example of the combustion device of the present invention.

[Explanation of symbols]

7 ... Gas burner (combustion section), 14 ... CO sensor, 25 ...
Operation control means, 26 ... Abnormality processing means.

Claims (6)

[Claims] 1. A CO sensor that outputs a signal of a level according to the CO concentration generated during the operation of the combustion section, and stops the operation of the combustion section when the output of the CO sensor exceeds a predetermined reference level. In a combustion device provided with an operation control means for controlling, when the output of the CO sensor is equal to or lower than a predetermined lower limit value set in advance, an abnormality processing means for performing a predetermined abnormality process is provided, and the lower limit value is When the combustion unit is not in operation or during normal combustion, the signal level in the steady state output by the CO sensor in the normal state is set as a reference and set to a value smaller than the signal level in the steady state by a predetermined amount. Characteristic combustion equipment. 2. The combustion apparatus according to claim 1, wherein the abnormality processing means performs the predetermined abnormality processing when the output of the CO sensor continues for a predetermined time and is below the lower limit value. . 3. The abnormality processing means includes means for temporarily raising and heating the CO sensor when the output of the CO sensor becomes equal to or lower than the predetermined lower limit value, and raises the temperature of the CO sensor. The combustion device according to claim 1, wherein the predetermined abnormality processing is performed when the output of the CO sensor again becomes equal to or lower than the predetermined lower limit value after heating. 4. The abnormality processing means carries out the predetermined abnormality processing when the output of the CO sensor remains below the lower limit for a predetermined period of time after the temperature of the CO sensor is raised and heated. The combustion device according to claim 3. 5. The combustion apparatus according to claim 1, wherein the abnormality processing by the abnormality processing means includes a processing for prohibiting the operation of the combustion section. 6. The combustion device according to claim 1, wherein the abnormality processing by the abnormality processing means includes alarm generation processing.