JP5019333B2 - Combustion device - Google Patents

Description

  The present invention relates to a combustion apparatus having a function of detecting abnormality of a thermistor that detects the temperature of a combustion flame of a burner.

  2. Description of the Related Art Conventionally, for example, in a gas water heater, a thermocouple that detects a temperature of a combustion flame of a burner is known, and a combustion state of the burner is detected by an electromotive force of the thermocouple (for example, Patent Document 1).

In the gas hot water supply apparatus described in Patent Document 1, when the electromotive force of the thermocouple falls outside the proper range, the incomplete combustion of the burner is performed by correcting the rotational speed of the fan that supplies combustion air to the burner. To prevent the generation of carbon monoxide and soot.
Japanese Patent No. 3060728

  It is conceivable to use a thermistor in addition to the thermocouple described above as an element for detecting the temperature of the burner combustion flame. However, since the thermistor is a calcined oxide, it deteriorates when placed in an environment above the calcining temperature or in a reducing atmosphere, and the original temperature / resistance characteristic cannot be maintained.

  Therefore, when the temperature of the burner combustion flame is detected using a thermistor, the thermistor deteriorates when the thermistor is exposed to a high temperature due to abnormal combustion of the burner or when the oxygen concentration in the air near the thermistor decreases. there is a possibility. When the thermistor for detecting the temperature of the combustion flame of the burner is deteriorated as described above, the combustion state of the burner cannot be accurately detected thereafter.

  Accordingly, an object of the present invention is to provide a combustion apparatus that can detect an abnormality due to deterioration of a thermistor that detects the temperature of a combustion flame of a burner.

  The present invention has been made in order to achieve the above object, and a burner, a combustion flame thermistor for detecting the temperature of the combustion flame of the burner, and the combustion state of the burner according to the detected temperature of the combustion flame thermistor A combustion state detecting means for detecting the ambient temperature, an ambient temperature sensor for detecting an ambient temperature around the burner, a detected temperature of the combustion flame thermistor when the burner is in a fire extinguishing state, and a detected temperature of the ambient temperature sensor Combustion flame thermistor abnormality detecting means for judging that the combustion flame thermistor is abnormal when the difference is equal to or greater than a predetermined determination temperature difference is provided.

  According to the present invention, when the combustion flame thermistor is deteriorated due to abnormal combustion or the like of the burner, the temperature / resistance characteristic of the combustion flame thermistor is entirely shifted from the high temperature side to the low temperature side. Tend. For example, when the detection temperature of the combustion flame thermistor is reduced by 50 ° C. with respect to the actual temperature of 700 ° C. on the high temperature side used for detecting the combustion state of the burner, the low temperature side when the burner is in the fire extinguishing state The detection temperature decreases by 50 ° C. even at 20 ° C.

  Therefore, when the combustion flame thermistor is deteriorated, a temperature difference is generated between the temperature detected by the combustion flame thermistor when the burner is in the fire extinguishing state and the temperature detected by the ambient temperature sensor in the normal state. Therefore, the combustion flame thermistor abnormality detection means is configured such that when the difference between the detection temperature of the combustion flame thermistor and the detection temperature of the ambient temperature sensor when the burner is in the fire extinguishing state is equal to or greater than the determination temperature difference. It can be determined that the combustion flame thermistor is abnormal.

  In addition, the determination temperature difference is set to a value that is a predetermined temperature higher than the temperature difference on the basis of the temperature difference between the temperature detected by the combustion flame thermistor and the temperature detected by the ambient temperature sensor at the time of assembly or start of use. It is characterized by.

  In the present invention, since the combustion flame thermistor is designed to detect a high temperature range in order to detect the combustion state of the burner, a certain temperature is detected in the normal temperature range detected by the ambient temperature sensor. Detection error may occur. Therefore, with the temperature difference between the detected temperature of the combustion flame thermistor and the detected temperature of the ambient temperature sensor at the time of assembly or start of use as a reference, a temperature difference larger than the temperature difference by a predetermined level is set as the determination temperature difference. Thus, the influence of the temperature detection error can be avoided and the abnormality of the combustion flame thermistor can be detected with higher accuracy.

  In addition, the combustion flame thermistor abnormality detection means calculates a time from when the burner switches from a combustion state to a fire extinguishing state until the temperature near the combustion flame thermistor becomes equal to the temperature near the ambient temperature sensor. It is determined whether or not the difference between the detected temperature of the combustion flame thermistor and the detected temperature of the ambient temperature sensor is equal to or greater than the determination temperature difference after an assumed stable time has elapsed. .

  According to the present invention, even when the burner is switched from the combustion state to the fire extinguishing state, the temperature near the combustion flame thermistor decreases until it becomes the same as the temperature near the ambient temperature sensor. It takes time. Therefore, after the stabilization time determined assuming this time has elapsed, it is determined whether or not the difference between the detected temperature of the combustion flame thermistor and the detected temperature of the ambient temperature sensor is equal to or greater than the determined temperature difference. By doing so, the abnormality of the combustion flame thermistor can be detected with higher accuracy.

  Further, the combustion flame thermistor abnormality detecting means is a predetermined number of times or more at a predetermined time interval, and when the difference between the detected temperature of the combustion flame thermistor and the detected temperature of the ambient temperature sensor is equal to or higher than the determination temperature difference, The combustion flame thermistor is determined to be abnormal.

  According to the present invention, the difference between the detected temperature of the combustion flame thermistor and the detected temperature of the ambient temperature sensor when the judgment temperature difference must be set to a small value due to the installation environment of the combustion device or the like. However, when the temperature difference instantaneously exceeds the determination temperature difference due to electrical noise or the like, the combustion flame thermistor abnormality detection means prevents the combustion flame thermistor from being erroneously detected as abnormal. Can do.

  An example of an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of an indoor gas heater that is a combustion apparatus according to the present invention. Referring to FIG. 1, a gas water heater of this embodiment includes a main body housing 1 installed indoors, a combustion chamber 2 accommodated in the main body housing 1, and a gas burner 3 ( (Corresponding to the burner of the present invention), a gas supply pipe 4 for supplying fuel gas to the gas burner 3, a water pipe 5 for supplying hot water to the kitchen or bathroom, etc., and combustion air x (outside air) of the gas burner 3 from the outside to the combustion chamber 2 is connected to the control unit 7 that controls the overall operation of the gas water heater, the supply / exhaust pipe 6 that sends the exhaust gas y generated in the combustion operation of the gas burner 3 to the outdoors, and the control unit 7. A remote controller 8 for remotely operating the water heater is provided.

  The air supply / exhaust pipe 6 includes an inner pipe 10 that forms an exhaust path 9 inside, and an external pipe 11 that is inserted approximately concentrically to the inner pipe 10 to provide an air supply path 11 for combustion air in a space between the inner pipe 10. A double tube structure is formed by the outer tube 12 to be formed, and extends from the upper part of the indoor body housing 1 to the outdoors.

  The indoor side end of the outer pipe 12 of the air supply / exhaust pipe 6 is connected to an opening 13 formed in the upper part of the main body housing 1, whereby the air supply path 11 inside the outer pipe 12 passes through the opening 13. And communicates with the inside of the main body housing 1.

  The main body housing 1 is formed in a substantially hermetically sealed structure, and the inside thereof is a fan 15 provided at the location of an air supply port 14 formed in the lower part of the combustion chamber 2 (for combustion via the air supply path 11 to the burner 3). Air is supplied to the inside of the combustion chamber 2 via a fan that discharges the combustion exhaust gas from the burner 3 through the exhaust passage 9.

  The indoor side end of the inner pipe 10 of the air supply / exhaust pipe 6 is introduced into the main body housing 1 from the outer pipe 12 and connected to an exhaust port 16 formed in the upper part of the combustion chamber 2. Therefore, the exhaust passage 9 inside the inner pipe 10 communicates with the inside of the combustion chamber 2 via the exhaust port 16. Note that the ends on the outdoor side of the inner pipe 10 and the outer pipe 12 of the air supply / exhaust pipe 6 are open to the atmosphere.

  Further, in the vicinity of the air inlet 14 of the combustion chamber 2, a supply for detecting the temperature of the combustion air (supply air temperature) supplied from the air supply passage 11 into the combustion chamber 2 through the inside of the main body housing 1. An air thermistor 17 (corresponding to the ambient temperature sensor of the present invention) is provided.

  The gas supply pipe 4 is connected to the burner 3, and a main electromagnetic valve 18, a proportional electromagnetic valve 19 and a sub electromagnetic valve 20 are provided in that order from the upstream side. The main solenoid valve 18 and the sub solenoid valve 20 open and close the gas supply pipe 4 to switch the supply / cutoff of the fuel gas to the burner 3. Further, the proportional solenoid valve 19 changes the amount of fuel gas supplied to the burner 3 by changing the opening of the gas supply pipe 4.

  The water flow pipe 5 includes a water inlet pipe 21, a heat exchanger pipe 22 and a bypass pipe 23 branched from the water inlet pipe 21, and a hot water outlet pipe 24 where the heat exchanger pipe 22 and the bypass pipe 23 merge. The downstream end is connected to a hot water tap (not shown) installed in a kitchen, bathroom, washroom or the like. The water flowing into the heat exchanger 25 from the inlet pipe 21 is heated by the burner 3 when flowing through the heat exchanger 25, and the heated water and the water flowing on the bypass pipe 23 side merge to produce the hot water. Supplyed to the tube 24.

  A water inlet thermistor 26 that detects the temperature of the water flowing through the water inlet pipe 21 (water inlet temperature), a flow rate sensor 27 that detects the flow rate of the water flowing through the water inlet pipe 21, and the water inlet pipe 21 are passed through the water inlet pipe 21. A water amount control valve 28 for adjusting the flow rate of water is provided. In addition, the hot water discharge pipe 24 is provided with a hot water discharge thermistor 29 that detects the temperature of the water flowing through the hot water discharge pipe 24 (temperature of discharged water).

  The combustion chamber 2 includes a flame rod 30 that detects the combustion flame of the burner 3, an ignition electrode 31 that generates a spark discharge and ignites the burner 3, and a combustion flame thermistor 36 that detects the temperature of the combustion flame of the burner 3. Is provided. An igniter 32 for applying a high voltage to the ignition electrode 31 is provided in the main body housing 1.

  The remote controller 8 is connected to the control unit 7 via a communication cable 33, and includes a temperature setting switch 34 for setting a target hot water supply temperature, and a display 35 for displaying an operation status of the gas water heater. .

  Next, FIG. 2 is a control block diagram of the gas water heater shown in FIG. 1. The control unit 7 is transmitted with setting data of the target hot water temperature from the remote controller 8 via the communication cable 33, Detection signals of the thermistor 26, the hot water thermistor 29, the flow sensor 27, the supply air thermistor 17, the frame rod 30, and the combustion flame thermistor 36 are input.

  The control unit 7 is an electronic unit composed of a microcomputer, a memory (not shown), and the like. Then, by causing the microcomputer to execute the control program for the hot water heater held in the memory, the control unit 7 is configured so that the combustion control means 50 for controlling the combustion operation of the gas burner 3 and the burner detected by the combustion flame thermistor 36. 3 functions as a combustion state detection means 51 that detects the combustion state of the burner 3 based on the temperature of the combustion flame 3 and a combustion flame thermistor abnormality detection means 52 that detects an abnormality in the combustion flame thermistor 36.

  The operations of the main solenoid valve 18, the sub solenoid valve 20, the proportional solenoid valve 19, the fan 15, the igniter 32, and the water amount control valve 28 are controlled by the control signal output from the control unit 7.

  When it is detected from the detection signal of the flow sensor 27 that the supply of water to the water pipe 5 has been started, the combustion control means 50 performs an ignition process for the burner 3 and starts the combustion operation of the burner 3. The combustion control means 50 determines the target combustion amount of the burner 3 in the combustion operation so that the detected temperature of the hot water thermistor 29 matches the target hot water supply temperature.

  Here, in the memory of the control unit 7, setting data of the target rotational speed of the fan 15 corresponding to the target combustion amount and the target opening degree of the proportional solenoid valve 19 are stored in advance, and the combustion control means 50 stores the setting data. The target rotational speed of the fan 15 is acquired from the data. The combustion control means 50 controls the rotational speed of the fan 15 to the target rotational speed, and controls the opening degree of the proportional solenoid valve 19 to the target opening degree.

  Next, the abnormality detection process of the combustion flame thermistor 36 by the combustion flame thermistor abnormality detection means 52 will be described according to the flowchart shown in FIG.

  The usable temperature range of the combustion flame thermistor 36 is, for example, about −30 ° C. to 900 ° C. Normally, the combustion flame thermistor 36 does not reach a high temperature exceeding the usable temperature range. However, due to abnormal combustion of the burner 3, the combustion flame thermistor 36 may be heated to a high temperature exceeding the usable temperature range, and the combustion flame thermistor 36 may be deteriorated.

  Here, when the combustion flame thermistor 36 deteriorates, the temperature detected by the combustion flame thermistor 36 decreases by a substantially constant temperature range from the low temperature range to the high temperature range. For example, when the detection temperature of the combustion flame thermistor 36 is 650 ° C., which is 50 ° C. lower than the actual temperature due to deterioration, the actual temperature 700 ° C. in the high temperature region, The detected temperature of the combustion flame thermistor 36 is −30 ° C., which is 50 ° C. lower than the actual temperature.

  When the degree of deterioration of the combustion flame thermistor 36 becomes large, the combustion state of the burner 3 cannot be accurately detected based on the detected temperature of the combustion flame thermistor 36. Therefore, the combustion flame thermistor abnormality detection means 52 performs processing for detecting the presence or absence of abnormality due to deterioration of the combustion flame thermistor 36.

  The combustion flame thermistor abnormality detection means 52 determines whether or not one hour (corresponding to the stabilization time of the present invention) has elapsed since the burner 3 was extinguished in STEP 1 of FIG. This one hour is determined by assuming the time from when the burner 3 is extinguished until the temperature around the burner 3 decreases and the ambient temperature of the combustion flame thermistor 36 and the supply air thermistor 17 becomes the same. It is.

  If 1 hour has elapsed since the burner 3 was extinguished, the process proceeds to STEP 2, and if 1 hour has not elapsed, the process branches to STEP 10. In STEP 10, the combustion flame thermistor abnormality detecting means 52 resets the counting variable CNT (CNT = 0), and returns to STEP 1.

  In STEP 2, the combustion flame thermistor abnormality detection means 52 has a temperature difference between the detected temperature TH 1 detected by the supply air thermistor 17 and the detected temperature TH 2 detected by the combustion flame thermistor 36 equal to or higher than 50 ° C. (corresponding to the judgment temperature difference of the present invention). It is determined whether or not 50 ° C. ≦ | TH1−TH2 |). When the temperature difference between the detected temperature TH1 detected by the supply air thermistor 17 and the detected temperature TH2 detected by the combustion flame thermistor 36 is 50 ° C. or more, the process proceeds to STEP 3, and when it is less than 50 ° C., the process branches to STEP 10.

  In STEP 3, the combustion flame thermistor abnormality detection means 52 counts up the counter variable CNT (CNT + 1 → CNT), and determines whether or not the value of the counter variable CNT has become 5 or more in STEP 4.

  When the value of the counter variable CNT becomes 5 or more, that is, in the loop of STEP1 to STEP4, five times continuously in STEP4 (corresponding to the predetermined number of times of the present invention), the detected temperature TH1 by the supply air thermistor 17 When the difference between the detected temperature TH2 and the detected temperature TH2 by the combustion flame thermistor 36 is determined to be 50 ° C. or more, the process proceeds to STEP5, and when the value of the count variable CNT is less than 5, the process branches to STEP1. The execution time of STEP1 to STEP4 corresponds to the predetermined period of the present invention.

  In STEP 5, the combustion flame thermistor abnormality detection means 52 prohibits the combustion operation of the burner 3 by the combustion control means 50, whereby the combustion operation of the burner 3 is executed in a state where the combustion state of the burner 3 cannot be detected. To avoid that. In subsequent STEP 6, the combustion flame thermistor abnormality detection means 52 displays an error display on the display 35 of the remote controller 8 on the display 35 of the remote controller 8 (see FIG. 1) indicating that the combustion flame thermistor 36 is in an abnormal state. Do. The error display prompts the user to repair or check the water heater.

  Here, if the combustion flame thermistor 36 is normal, the detection temperature TH1 detected by the supply air thermistor 17 and the detection temperature TH2 detected by the combustion flame thermistor 36 substantially coincide. Therefore, when the temperature difference between the detected temperature TH1 detected by the supply air thermistor 17 and the detected temperature TH2 detected by the combustion flame thermistor 36 is 50 ° C. or more, it can be determined that the combustion flame thermistor 36 is in an abnormal state.

  The combustion flame thermistor abnormality detecting means 52 continues five times when the temperature difference between the detected temperature TH1 of the supply air thermistor 17 and the detected temperature TH2 of the combustion flame thermistor 36 is 50 ° C. or more in the loop of STEP1 to STEP4. When it is determined in STEP 2, it is detected that the combustion flame thermistor 36 is abnormal, and the processing of STEP 5 and STEP 6 is executed.

  As described above, when the temperature difference between the detected temperature TH1 of the supply air thermistor 17 and the detected temperature TH2 of the combustion flame thermistor 36 is 50 ° C. or more, the combustion flame thermistor 36 is abnormal when it is determined five times consecutively. When the difference between the detected temperature TH1 detected by the supply air thermistor 17 and the detected temperature detected by the combustion flame thermistor 36 becomes 50 ° C. or more instantaneously due to electrical noise or the like, Execution of processing can be avoided.

  The determination temperature difference of 50 ° C. in STEP 2 is determined in consideration of the influence of the change in the detection temperature due to the deterioration of the combustion flame thermistor 36 on the detection of the combustion state of the burner 3. Here, in FIG. 4, the left vertical axis is set to the carbon monoxide concentration (ppm) in the air, the right vertical axis is set to the temperature detected by the combustion flame thermistor 36, and the horizontal axis is the excess air ratio (λ , The ratio of the supply amount of combustion air to the supply amount of fuel gas), and the relationship between the excess air ratio and the detected temperature of the combustion flame thermistor 36 is indicated by a, and the excess air ratio and carbon monoxide in the air The relationship with the density is indicated by b.

  Referring to FIG. 4, when deterioration of combustion flame thermistor 36 occurs and the temperature detected by combustion flame thermistor 36 changes by ΔT (P1a → P2a), the corresponding change in carbon monoxide concentration in air ΔCo (P1b → Change in P2b) is 280 ppm → 420 ppm. If the detection accuracy of carbon monoxide is deteriorated to such an extent, it is possible to determine the combustion state of the burner 3 based on the detection temperature of the combustion flame thermistor 36. Therefore, in this embodiment, the determination temperature difference is It is set to 50 ° C.

  In the present embodiment, the gas water heater is shown as the combustion apparatus of the present invention. However, the present invention can be applied to any combustion apparatus that detects the combustion state of the burner by detecting the temperature of the combustion flame of the burner with a thermistor. Can be applied.

  Further, when determining the judgment temperature difference, the temperature difference between the detected temperature of the supply air thermistor 17 and the detected temperature of the combustion flame thermistor 36 is measured at the time of assembling the water heater or installing the water heater in the factory. A temperature difference larger than the difference by a predetermined level (for example, 50 ° C. described above) may be determined as the determination temperature difference. In this case, the abnormality of the combustion flame thermistor 36 can be detected by eliminating the influence of the difference (temperature detection error) between the detected temperature of the supply air thermistor 17 and the detection temperature of the combustion flame thermistor 36 in the initial stage.

  In the present embodiment, as shown in FIG. 2, when the temperature difference between the detected temperature by the supply air thermistor 17 and the detected temperature by the combustion flame thermistor 36 is equal to or larger than the determination temperature difference, it is continuously performed five times or more. When it is determined that the combustion flame thermistor 36 is abnormal, it may be detected that the combustion flame thermistor 36 is abnormal when it is determined once.

  In the present embodiment, the supply air thermistor 17 is used as the ambient temperature sensor of the present invention. For example, in a hot water heater installed outdoors, an outside temperature thermistor provided for performing an anti-freezing operation is used. The atmospheric temperature sensor of the present invention may be used. In addition, an ambient temperature sensor may be provided exclusively.

BRIEF DESCRIPTION OF THE DRAWINGS The whole block diagram of the gas water heater which is a combustion apparatus of this invention. The control block diagram of the gas water heater shown in FIG. The flowchart of the abnormality detection process of a combustion flame thermistor. Explanatory drawing about determination of the judgment temperature difference.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Main body housing, 2 ... Combustion chamber, 3 ... Burner, 7 ... Control unit, 17 ... Supply air thermistor (atmosphere temperature sensor), 36 ... Combustion flame thermistor, 50 ... Combustion control means, 51 ... Combustion state detection means, 52 ... Combustion flame thermistor abnormality detection means

Claims (4)

With a burner,
A combustion flame thermistor for detecting the temperature of the combustion flame of the burner;
Combustion state detection means for detecting the combustion state of the burner according to the detected temperature of the combustion flame thermistor;
An ambient temperature sensor for detecting the ambient temperature around the burner;
When the difference between the detected temperature of the combustion flame thermistor when the burner is in the fire extinguishing state and the detected temperature of the ambient temperature sensor is equal to or greater than a predetermined determination temperature difference, the combustion flame thermistor is abnormal. A combustion apparatus comprising: a combustion flame thermistor abnormality detecting means for judging. The combustion apparatus according to claim 1, wherein
The determination temperature difference is set to a value larger than the temperature difference by a predetermined temperature with reference to the temperature difference between the temperature detected by the combustion flame thermistor and the temperature detected by the ambient temperature sensor at the time of assembly or start of use. Combustion device characterized by that. The combustion apparatus according to claim 1 or 2,
The combustion flame thermistor abnormality detection means assumes a time from when the burner switches from a combustion state to a fire extinguishing state until the temperature near the combustion flame thermistor and the temperature near the ambient temperature sensor become the same. After the stabilization time determined in this step elapses, it is determined whether or not the difference between the temperature detected by the combustion flame thermistor and the temperature detected by the ambient temperature sensor is equal to or greater than the determination temperature difference. . The combustion apparatus according to any one of claims 1 to 3,
The combustion flame thermistor abnormality detection means is configured to perform the combustion when a difference between a detection temperature of the combustion flame thermistor and a detection temperature of the ambient temperature sensor is equal to or greater than the determination temperature difference at a predetermined time interval. A combustion apparatus characterized by determining that a flame thermistor is abnormal.

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