JP3403886B2 - Combustion equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus for stopping combustion based on detection of carbon monoxide (CO) by a CO sensor. 2. Description of the Related Art Conventionally, in order to prevent incomplete combustion of gas combustion equipment which causes carbon monoxide poisoning, a CO sensor is provided in an exhaust pipe downstream of a gas burner, and a detection signal of the CO sensor is provided. 2. Description of the Related Art There is known a combustion device provided with a safety device that issues an alarm or stops gas combustion in response. For example, there is a safety device for a gas combustor proposed in JP-A-5-26440. This device detects the CO concentration in the exhaust gas from the gas burner using a CO sensor, issues an alarm when this concentration exceeds the first reference concentration, and further increases the CO concentration by recirculation of the exhaust gas to increase the second reference concentration. If exceeded,
The gas supply flow path to the gas burner is closed to stop the gas supply. Further, even when the combustion by the gas burner continues for a predetermined period in a state where the alarm is issued when the CO concentration exceeds the first reference concentration, the gas supply is stopped. As a result, C
Even if the O concentration is low, the gas supply is stopped if the combustion is continued for a predetermined period after the alarm.
Outflow was excellent to stop. [0003] However, there is a case where usability is poor depending on the setting of the reference density used for the comparison and judgment. For example, if the first reference concentration is set lower in consideration of safety, an alarm is issued with a slight generation of CO,
If the state is continued, the gas supply is stopped. Therefore, even in the normal use state, the combustion may frequently stop. If the first reference concentration is set higher than this, if the amount of CO generation is large, the CO concentration may exceed an allowable level for a predetermined period from when an alarm is issued to when the gas supply is stopped. . An object of the present invention is to solve the above-mentioned problems and to make the combustion device safer and more convenient to use. According to a first aspect of the present invention, there is provided a burner for burning fuel gas, and a CO concentration in an exhaust gas provided in an exhaust gas passage of the burner. Sensor, an incomplete combustion confirming means for comparing the CO concentration detected by the CO sensor with a preset reference value, and detecting a CO concentration equal to or higher than the reference value to the burner. A gas supply stopping means for stopping fuel gas supply,
The reference value to be compared with the detected CO concentration is set according to the burning time of the burner ,
The gist of the present invention is that reference value changing means for changing the value to be lower than the reference value is provided. [0005] In the combustion apparatus according to the first aspect of the present invention having the above configuration, the reference value of the CO concentration is changed according to the burn time of the burner. That is, when the combustion time is short, the reference value is set high, and when the combustion time is long, the reference value is changed low. Then, when the incomplete combustion confirming means confirms the detection of the CO concentration equal to or higher than the reference value, the gas supply stopping means stops the supply of the fuel gas to the burner. In general, in a combustion device, the combustion state deteriorates as the combustion progresses, and CO generation increases. Even a slight generation of CO has an effect on the human body over time. Therefore, in consideration of this point, even if the CO concentration is low due to the slight generation of CO, the combustion apparatus changes the reference value to a low value when the combustion time becomes long, so that the reference value is not exceeded. Stop burning. On the other hand, even if a large amount of CO is generated and the concentration of CO is high, if the combustion time is short, it can be used sufficiently without stopping combustion. That is, the combustion can be stopped precisely at a safe time in response to the combustion time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of the combustion apparatus of the present invention will be described below. FIG. 1 is a schematic configuration diagram of a water heater with an incomplete combustion prevention device as one embodiment. A gas burner 11 is provided at a lower portion of a case 10 forming a combustion chamber of the water heater, and fuel gas is supplied through a gas supply path 14 having a main solenoid valve 12 and a proportional solenoid valve 13 arranged in series from a gas supply source side. Supplied. The original electromagnetic valve 12 is a valve that only opens and closes the gas flow path, and the proportional electromagnetic valve 13 is a control valve that is set to an opening degree according to a control signal and adjusts the gas supply amount to a desired value. A fan 15 is provided at the bottom of the case 10.
Is supplied to the case 10 in an amount corresponding to the gas supply amount. A heat exchanger 16 is disposed above the gas burner 11, and the water passed through a water supply pipe 17 is supplied to the gas burner 1.
It is heated by the heat of combustion in 1 and sent out to the hot water supply pipe 18. The upper part of the case 10 above the heat exchanger 16 has a hood 19
Through the exhaust pipe 20. And this exhaust stack 2
A CO sensor 21 for detecting the CO concentration at 0 is mounted. A controller 23 for controlling the combustion and the like is provided in the main body of the water heater. The controller 23 includes a CPU, a RAM, and a ROM, which constitute a well-known arithmetic and logic operation circuit (not shown), an input interface for inputting signals from various sensors, an output interface for outputting drive signals to various actuators, and the like. Then, based on the signal from the CO sensor 21,
It not only opens and closes the solenoid valves 12 and 13 but also controls hot water temperature,
Although ignition control and the like are also performed, explanations and illustrations of sensors, ignition devices, and the like that are not directly related to the present invention are omitted. FIG. 2 is a flowchart showing an incomplete combustion prevention control routine executed by the controller 23.
Starts in accordance with the ignition operation. When the ignition operation of the water heater is started by an unillustrated ignition operation and this routine is started, first, the flame of the gas burner 11 is detected by an unillustrated sensor (S11, YES). Thus, when the ignition of the gas burner 11 is confirmed, the combustion timer is started and the discharge of the ignition igniter (not shown) is stopped (S
12), control of the hot water temperature is started (S13). Immediately after ignition, a large amount of CO is temporarily generated, and combustion is not in a steady combustion state. Therefore, a predetermined time (for example, 2 minutes) elapses, and the system waits for stabilization. After the predetermined time (2 minutes) elapses (S14, YE)
S), CO determined in advance according to the combustion time T (2 minutes)
A reference value A (for example, 1000 ppm) of the concentration is selected from the table (S15). Next, the CO concentration N in the exhaust gas is detected by the CO sensor (S16), and the detected CO concentration N is compared with the selected reference value A (1000 ppm) (S17). At this time, if the detected CO concentration N exceeds the reference value A (S17, NO), the original solenoid valve 12 is closed (S1).
8) The supply of the fuel gas is stopped, and an abnormality is displayed (S19). If the detected CO concentration N is equal to or less than the reference value A (S17, YES), the process proceeds to step 15, and the process is continuously and continuously repeated. The reference value A is determined so as to decrease stepwise according to the combustion time T. For example, when the combustion time T is 0 <T ≦ 5 minutes, the reference value A = 1000 pp
m, A = 900 ppm for 5 minutes <T ≦ 10 minutes, and A = 700 ppm for 10 minutes <T ≦ 15 minutes. Therefore, when the time (3 minutes) further elapses, the combustion time T (2
(Minute + 3 minutes = 5 minutes), a new reference value A of the CO concentration predetermined from the table is selected and the reference value A = 1
The standard value A was used for comparison using 000 ppm.
= 900 ppm (S15) and a comparison is made. Similarly, the CO sensor detects the CO concentration N in the exhaust gas (S16), and compares the detected CO concentration N with a newly selected reference value A (900 ppm) (S17). Thus, while the combustion is continued, the reference value A is gradually decreased, for example, every 5 minutes, and is compared with the detected CO concentration N. Although not shown, the original solenoid valve 12 is also closed during combustion by fire extinguishing operation by a user or activation of various safety devices (for example, thermocouple electromotive force drop due to misfire) (S18). Next, a technique for determining the reference value A will be described. In general, when CO is generated and leaks to a room or the like in a gas combustion device, the time lapse and CO in the room are considered.
As for the relationship with the concentration, as shown in FIG. 4, the CO concentration increases with the combustion time, and exceeds the allowable level after a lapse of a predetermined time. At this time, the CO concentration detected from the CO sensor of the gas combustion device varies depending on the variation in output characteristics of the CO sensor with respect to the actual CO concentration and the variation in the device, and the time required to reach the reference value varies. N
2, N3, N4 (N1 <N2 <N3 <N4), the times T1, T2, T3, T4 (T1>T2>T3>, respectively)
T4). Assuming that the reference value of the CO concentration of the combustion device is N1 in anticipation of the safety when the gas combustion device is used for a long time, such a variation causes the CO concentration N2 actually having a room for safe use in a short time. , N
Even in the case of 3, N4, combustion stops. In order to eliminate such inconveniences, as shown in FIG. 5, corresponding reference values A1, A2, A3, and A4 are determined from the combustion times T1, T2, T3, and T4. Allows the value A to be selected. That is, the reference value A4 when the combustion time T4 is 0 <T4 ≦ ta, the reference value A3 when the combustion time T3 is ta <T3 ≦ tb, and the reference value when the combustion time T2 is tb <T2 ≦ tc. A2 is selected, and the reference value A1 is selected when the combustion time T1 satisfies tc <T1 ≦ td. According to the water heater with an incomplete combustion preventing device, when the combustion time T is short, the reference value A of the CO concentration is set high, and when the combustion time T is long, the reference value A is changed to be low. When the controller 23 confirms that the CO concentration is higher than the reference value, the gas burner 11
Since the supply of the fuel gas to the fuel cell is stopped, even if the detected CO concentration is low, it is possible to prevent the combustion time from becoming longer and exceeding the allowable level. On the other hand, even if the detected CO concentration is high, if the combustion time is short, it is safe and can be used without stopping the combustion. In other words, there is still room for safe use C
In the case of the O concentration, there is no inconvenience that combustion is stopped unnecessarily, and the usability is good. Next, another embodiment for determining the reference value A will be described with reference to FIG. FIG. 3 is a flowchart showing an incomplete combustion prevention control routine executed by the controller 23. The same parts as those in the previous embodiment are denoted by the same reference numerals and description thereof will be omitted. As in the previous embodiment, when two minutes have passed since the water heater was ignited by an ignition operation (not shown) and combustion started (S14, YES), the first CO concentration N0 is detected (S20). Initial CO concentration N0 (eg, 200
The first reference value A0 of the CO concentration is calculated (for example, 200 ppm.times.5 times = 1000 ppm) by a relational expression determined in advance according to (ppm) (S21). Next, a reference value A is determined from the calculated first reference value AO (S22). The reference value A is determined according to the combustion time T according to the following equation: A = A0 × K (T) K (T): time coefficient. The time coefficient K (T) refers to the table. For example, when the combustion time T is 0 <T ≦ 5 minutes, K
(T) = 1, K (T) = 0.9 when 5 minutes <T ≦ 10 minutes
And K (T) = 0.7 in 10 minutes <T ≦ 15 minutes. Therefore, when the combustion time T is 0 <T ≦ 5 minutes, the reference value A = 1000 ppm, A = 900 ppm for 5 minutes <T ≦ 10 minutes, and A = 700 for 10 minutes <T ≦ 15 minutes.
Use ppm. Thereafter, the CO concentration N is detected in the same manner as in the previous embodiment (S16), and comparison is made using this reference value A. This water heater with an incomplete combustion preventing device has a CO
The reference value A0 is determined based on the detected concentration value, and thereafter, the reference value A0 is changed according to the combustion time T. Therefore, even if there is a variation in the detection characteristics of each CO sensor with respect to the actual CO concentration, the detection value N0 of each CO sensor
By determining the reference value A from, the increase in the CO emission concentration can be properly detected, and the variation in the detection characteristics of the individual CO sensors can be dealt with. In other words, even if the same reference value is set uniformly for any of the combustion devices, the combustion stop timing will differ if the detection characteristics of the individual CO sensors vary, but the initial CO detection value N0 will be the same as the actual CO detection value N0. The reference value A0 is determined, and the reference value A0 is determined according to the combustion time T.
By changing 0, an increase in CO can be reliably detected. The embodiments of the present invention have been described above.
The present invention is not limited to these embodiments at all, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention. For example, in the previous embodiment, in step 15, the reference value A was selected with reference to the table, but as shown in FIG. 5, the relational expression A = f (T) between the combustion time T and the reference value A was calculated. The reference value A may be determined by calculation and calculated. In this case, the reference value A can be continuously determined for an arbitrary combustion time T, and more detailed control can be performed. Alternatively, the reference value A
In the embodiment for determining the time coefficient K
Although (T) is selected stepwise with reference to the table, a relational expression continuously determined according to the combustion time T may be obtained, and the time coefficient K (T) may be obtained by calculation. . Also in this case, the reference value A can be continuously determined for an arbitrary combustion time T, and more detailed control can be performed. [0015] As described in detail above, claim 1 of the present invention.
The described combustion apparatus changes the reference value of the CO concentration in accordance with the burning time of the burner, and can respond in detail according to the burning time. Therefore, the combustion device can be used until it reaches the actual allowable level, and it is easy to use. On the other hand, when the combustion time becomes long and approaches an allowable level, the gas supply is stopped early, so that the safety is high.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a water heater with an incomplete combustion prevention device as one embodiment. FIG. 2 is a flowchart illustrating an incomplete combustion prevention control routine. FIG. 3 is a flowchart illustrating a process of determining a reference value. FIG. 4 is a graph showing a time change of a CO concentration. FIG. 5 is a graph showing a relationship between a combustion time and a reference value. [Description of Signs] 10 Case 11 Gas burner 12 Primary solenoid valve 13 Proportional solenoid valve 14 Gas supply path 20 Exhaust cylinder 21 CO sensor 23 Controller

Claims (1)

(57) [Claims 1] A burner for burning fuel gas, a CO sensor provided in an exhaust gas passage of the burner for detecting a CO concentration in exhaust gas, and a CO concentration detected by the CO sensor. Combustion comprising incomplete combustion confirmation means for comparing with a preset reference value, and gas supply stopping means for stopping supply of fuel gas to the burner when the detection of CO concentration equal to or more than the reference value is confirmed. In the apparatus, a reference value to be compared with the detected CO concentration is set according to the burning time of the burner ,
A combustion device comprising a reference value changing means for changing the value to be lower than the reference value.