JP3365714B2 - Combustion equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a combustion device that carries out an operation of stopping combustion or increasing the amount of air when it detects abnormal combustion by detecting the combustion state of a burner.

[0002]

2. Description of the Related Art Conventionally, in a combustion apparatus using gas fuel, the flame current value of the burner (frame rod (F
There is known a device that, when (R) current value) exceeds a predetermined threshold value, determines that the combustion is abnormal and stops the combustion operation (see JP-A-59-145422).

[0003]

By the way, as a method of determining the combustion state using the flame rod sensor, the FR current detection value read at the time of combustion of the burner and the FR stored in advance for the abnormal combustion determination are used. It is general to judge whether or not the combustion is abnormal based on the result of comparison with the threshold value of the electric current.

However, when the component and concentration of the fuel differ depending on the gas species used as the gas fuel in the above combustion apparatus, it is clear from the FR current value-CO concentration characteristic curve (~) shown by the solid line, dotted line and broken line in FIG. As described above, the tendency of the change in the FR current value (the relationship between the combustion state indicated by the CO concentration and the FR current value) differs for each gas type. Therefore, if the method of determining whether or not abnormal combustion is performed using the preset threshold value of the FR current as described above, the combustion state may be erroneously determined, and it is possible to accurately determine whether or not abnormal combustion occurs. There was a problem that it could not be judged.

Therefore, in view of the above, the gas species used is identified based on the FR current detection value in the normal combustion state immediately after the installation of the combustion apparatus, and the combustion state determination suitable for the gas species is performed. The method of setting the threshold was also considered. However, in this method, as shown in FIG.
It was difficult to accurately determine the combustion state when using a gas type in which the R current detection value is the same but the FR current detection value during abnormal combustion is completely different.

Therefore, an object of the present invention is to provide a combustion apparatus capable of setting an appropriate threshold value for judging the combustion state by accurately identifying the gas species used.

[0007]

A combustion apparatus according to the present invention supplies gas fuel and air to a burner for combustion, and a combustion state detecting means for detecting a combustion state of a flame of the burner and a combustion state detecting means. A threshold value storage unit that stores a plurality of threshold values for determining an abnormality, and a first combustion state detection value that the combustion state detection unit outputs in the initial state of the device, and an output when the air-fuel ratio is forcibly changed. The second combustion state detection value is compared to identify the gas species in use, and a selection unit that selects a threshold value corresponding to the identified gas species from a plurality of stored threshold values.

According to this structure, the first combustion state detection value output when the device is in the initial state and the second combustion state detection value output when the air-fuel ratio is forcibly changed are used by comparison. Since it was decided to identify the gas type inside and to select a threshold value corresponding to the identified gas type from a plurality of stored threshold values, it is possible to set a threshold value suitable for the gas type being used. .

In a preferred embodiment of the present invention, the threshold value storage means is expected to use a comparison value between the first combustion state detection value and the second combustion state detection value, and a threshold value corresponding to this comparison value. It is memorized for each gas type. Therefore, by obtaining the above-mentioned comparison value, it is possible to select the threshold value suitable for the gas type used from the threshold value storage means.

In a preferred embodiment of the present invention, the first
The combustion state detection value of is the combustion state detection value when the combustion state of the burner is normal and is the best. In this embodiment, a threshold value holding unit that holds the selected threshold value and a determination unit that determines an abnormality in the combustion state based on the combustion state detection value from the combustion state detection unit and the held threshold value are further provided. ing. The second combustion state detection value is obtained by forcibly changing the air-fuel ratio so that the air amount becomes excessive.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present embodiment will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing the overall construction of a combustion apparatus according to an embodiment of the present invention.

The above apparatus comprises a combustion section 100 and a control section 200.

The combustion section 100 burns the supplied mixture of gas fuel and air to supply heat to, for example, a hot water supply heat exchanger (not shown) of the water heater, and the burner 2
A gas supply pipe 4, a gas proportional valve 6, a gas solenoid valve (open / close valve) 8, an outside air suction fan 9, and a frame sensor 1.
With 0 and.

The burner 2 burns the supplied mixture of gas fuel and air to form a flame 1. Gas supply pipe 4
Connects a gas supply source (not shown) to the burner 2.
The gas proportional valve 6 is provided in the gas supply pipe 4 for adjusting the amount of gas supplied from the gas supply source to the burner 2. Further, the gas solenoid valve 8 is provided in the gas supply pipe 4 in order to disconnect / connect the gas supply from the supply gas source to the burner 2.
The outside air suction fan 9 supplies the burner 2 with primary air for forming an air-fuel mixture together with gas fuel, and secondary air for supplementing oxygen separately from the primary air. Frame sensor 10
Detects and outputs the FR current, and has a detection unit 11 necessary for detecting the FR current. The detector 11 is supported by an insulating member (not shown) and faces the flame outlet of the burner 2.

The control unit 200 controls the gas proportional valve 6 and the above-mentioned gas proportional valve 6 based on the output from the frame sensor 10.
It controls the gas on-off valve 8, the outside air suction fan 9, and the like, and includes a combustion control unit 12, an abnormal combustion detection unit 14, a threshold value selection unit 16, and a threshold value selection table 18 as functional elements therefor. .

The combustion control unit 12 receives the FR current detection signal from the flame sensor 10 and the notification from the abnormal combustion detection unit 14, and inputs the gas proportional valve 6, the gas on-off valve 8 and the outside air suction fan 9 to each other. Etc. are driven to control the start and stop of combustion in the burner 2, the combustion amount, and the like, and notify the threshold value selection unit 16 of information related to this combustion amount.

The abnormal combustion detector 14 is a flame sensor 1.
Based on the FR current detection signal from 0 and the FR current threshold value 20 read from the storage unit (not shown) included in the control unit 200, it is detected whether the combustion state of the burner 2 is abnormal, and the detection result is detected. Notify the combustion control unit 12. Here, the storage unit (not shown) is a RAM or an EEP.
It is composed of a ROM, and the threshold 20 is the threshold selection unit 1
6 is selectively read from the threshold selection table 18 and written in the storage unit.

The threshold selection table 18 is stored in a storage area in a ROM (not shown), for example, in the form shown in FIG. This table 18 is a comparison result of two FR current values detected under different conditions, which are set in advance for each gas type that can be assumed to be used, and a threshold value of the FR current for determining whether abnormal combustion occurs. Memorize The threshold selection table 18 will be described in detail with reference to FIG.

The threshold value selecting section 16 inputs the FR current detection signal from the flame sensor 10 and, at the same time, the combustion control section 1
Information on the amount of combustion from 2 is monitored. Then, when it is recognized that the combustion of the burner 2 has started, the gas species used as fuel is determined by executing the process for determining the threshold value as shown in FIG. 6, and the threshold value selection is performed based on the determination result. The corresponding threshold value 20 is selected from the table 18 and written in the storage unit (not shown).

FIG. 2 shows a fan rotation speed-CO concentration characteristic curve when the gas type 13A-1 is used for combustion with the combustion number 16 in the combustion apparatus having the above structure. The fan speed indicates the amount of air supplied to the burner 2, and the CO concentration indicates the combustion state of the burner 2.

Here, the CO concentration in the exhaust gas is 2000 pp
If the state of m or more is defined as abnormal combustion, in FIG. 2, it is determined that abnormal combustion occurs when the fan rotation speed becomes 2500 rpm or less. On the other hand, the fan speed is 300
At 0 rpm or more, the CO concentration in the exhaust gas becomes less than 100 ppm, and the optimum combustion state in combustion number 16 is achieved.
When the fan speed is less than 3000 rpm, the fuel gas is in an excess gas rich state, and when it is 3000 rpm or more, the air is in an excess air rich state. Therefore, the combustion control unit 1
In No. 2, the fan 9 is controlled so that the rotation speed of the fan is 3000 rpm in order to perform optimal combustion with the combustion number 16. The fan speed-CO concentration characteristics of the gas species 13A-2 and 13A-3 also have characteristics similar to those of the gas species 13A-1, although not shown.

FIG. 3 shows the FR current value for each gas type when the combustion apparatus having the above-mentioned structure is used and the gas types 13A-1, 13A-2, and 13A-3 are burned with the combustion number 16 respectively. -Shows a fan speed characteristic curve.

In FIG. 3, the curve indicates the gas species 13A-
1 shows the FR current value-fan rotation speed characteristic, the curve shows the FR current value-fan rotation speed characteristic of the gas species 13A-2, and the curve shows the FR current value-fan rotation speed characteristic.

As is apparent from FIG. 3, the FR current value when it is determined that the combustion is abnormal due to the fan speed becoming 2500 rpm, that is, the threshold value of the FR current for determining whether the combustion is abnormal or not. , 275 for gas type 13A-1
μA, about 225 μA for the gas species 13A-2, and about 160 μA for the gas species 13A-3.

On the other hand, the FR current detection value when it is determined that the combustion state is the optimum combustion state with the combustion number 16 because the fan rotation speed has reached 3000 rpm is the same for the gas species 13A-1 and the gas species 13A-2. Both are about 145 μA and about 110 μA for the gas species 13A-3. As described above, the FR current value detected when the abnormal combustion state occurs due to the fan rotation speed reaching 2500 rpm differs depending on the gas type.

FIG. 5 shows the threshold selection table 1 shown in FIG.
8 shows a threshold selection table of the FR current set for each gas type as an example of No. 8.

The threshold selection table 18 shown in FIG. 5 detects the FR current detection value in the normal combustion state and the FR current detection when the fan speed is forcibly increased to change the air-fuel ratio to the air rich side. It is used when the type of gas used is identified from the result of comparison with the value and the FR current threshold value suitable for the type of gas is selected. The FR current detection value in a normal combustion state is read when a predetermined condition as described in detail in FIG. 6 is satisfied in a normal combustion state immediately after the combustion device is installed. is there.

In FIG. 5, αFR is the FR current value FRa at the time of normal combustion and when the air-fuel ratio is forcibly changed (= the fan rotational speed is forcibly increased by a predetermined rotational speed to change the air-fuel ratio to the air rich side). Is a result of comparison with the FR current value FRb. This comparison result is, for example, FRa and FRb.
Ratio (FRa / FRb or FRb / FRa) or the difference between FRa and FRb (FRa-FRb or FR
b-FRa).

For example, the value of αFR is αFR ≦ 1.00
If so, the expected gas type is 13A-3, so the appropriate threshold value of the FR current for determining whether abnormal combustion is 160 μA. Next, the value of αFR is 1.01
If ≦ αFR ≦ 1.20, the expected gas type is 13A
Since it is -2, the appropriate threshold of the FR current is 225 μA.
Is. Furthermore, if the value of αFR is 1.21 ≦ αFR, the expected gas species is 13A-1, so the appropriate threshold value for the FR current is 275 μA.

Next, the processing operation for selecting the threshold value of the FR current in the above configuration will be described with reference to the flowchart of FIG.

Generally, at the start of combustion of the burner 2, the combustion state is normal and the best (CO concentration is minimum).
In other words, when the gas type 13A-1 is used, the burner 2 has the FR current value shown in FIG.
Combustion occurs at an operating point a located at the left end of the CO concentration characteristic curve. Also, when the gas species 13A-2 is used,
At the start of combustion, an operating point b (gas species 13A-) located at the left end of the FR current value-CO concentration characteristic curve shown in FIG.
The same as the operating point 1). Furthermore, gas type 13A-
3 is used, at the start of combustion, as shown in FIG.
Combustion occurs at the operating point c located at the left end of the FR current value-CO concentration characteristic curve shown in FIG.

Therefore, in a normal combustion state immediately after the combustion device is installed (step S1), it is determined whether or not predetermined conditions such as stable FR current value, stable combustion amount, and continuous combustion for a predetermined time are satisfied. Is checked (step S
2). As a result, if the above conditions are satisfied, the FR current value FRa is read and the forced mode after step S4 is entered (step S3). That is, reading the FR current value FRb when the air-fuel ratio is forcibly changed, FRb and FRa
Calculation of αFR that is the result of comparison with the threshold value selection table 18 for the threshold value 20 of the appropriate FR current based on this αFR (see FIG. 5).
(Refer to FIG. 4) and storing the threshold value 20 of the FR current. The forced mode is released after a predetermined time, and the normal combustion control mode is restored.

In this forced mode, first, the fan 9
Increases the number of revolutions by 200 rpm (step S4), and then activates a timer (not shown) built in the control unit 200 in order to check whether or not a predetermined time has elapsed after shifting to the forced mode. Step S
5). Then, it is checked whether or not conditions for canceling the forced mode such as exceeding the predetermined range of the outlet heated water temperature, inputting a fire extinguishing request, and exceeding the predetermined range of the required number of combustion amount are satisfied (step S6). As a result, if the release condition is satisfied, the forced mode is released and the normal combustion control is switched to (step S7).

As a result of the check in step S6, if the release condition is not satisfied, the FR current value is stable, the actual combustion number is stable (that is, the stable combustion is actually performed at the designated number). It is checked whether or not a predetermined condition such as is satisfied (step S8). As a result, if the above conditions are not satisfied, it is checked whether the timer started in step S5 has timed out (step S9).
If the time is over, the forced mode is released and the normal combustion control operation is switched (step S1).
0).

On the other hand, as a result of the check in step S8,
If the above conditions are satisfied, the FR current value FRb is read (step S11), and αFR is obtained as the comparison result of this FRb and FRa read in step S3 (step S12). Next, the threshold 20 corresponding to this αFR is selected from the threshold selection table 18 shown in FIG. 5 (step S13). Then, the selected threshold 20 is stored in the storage unit (not shown) described above (step S14). After that, unless there is a change in the type of gas used, when determining whether the burner 2 is abnormally burning,
The control unit 200 will use the threshold value 20 stored in the storage unit in step S14.

According to the above configuration, the FR current value FRa when the predetermined condition is satisfied in the normal combustion state immediately after the installation of the combustion device and the FR current value FRb when the air-fuel ratio is forcibly changed. The gas type is identified from the comparison result αFR, and the FR current threshold value 20 for determining abnormal combustion is selected from the table 18 accordingly.
Therefore, it is possible to set the threshold value 20 to a value suitable for the characteristics of the gas species used, thereby preventing erroneous detection of abnormal combustion.

Further, after identifying the gas type, it is possible to correct the combustion operation line so that the air-fuel ratio becomes suitable for the gas type.

It should be noted that the above content is only related to one embodiment of the present invention, and does not mean that the present invention is limited to the above content. That is, in the present embodiment, as the means for detecting the combustion state of the apparatus, the combustion apparatus provided with the frame rod has been described as an example, but the present invention detects the combustion state with the CO sensor, the exhaust thermistor, or the like. Of course, it is also applicable to a combustion device provided as a means for doing so.

[0040]

As described above, according to the present invention,
By accurately identifying the gas species to be used, it is possible to provide a combustion device capable of setting an appropriate threshold value for combustion state determination.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a combustion device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a fan rotation speed-CO concentration characteristic curve for a predetermined gas type.

FIG. 3 is a diagram showing an FR current value-fan rotation speed characteristic curve for each gas type.

FIG. 4 is a diagram showing an FR current value-CO concentration characteristic curve for each gas type.

FIG. 5 is a diagram showing a threshold table of FR current for each gas type.

6 is a flowchart showing a processing operation of the configuration of FIG.

[Explanation of symbols]

1 flame 2 burners 4 gas supply pipes 6 gas proportional valve 8 Gas solenoid valve (open / close valve) 9 Outside air suction fan 10 frame sensor 11 Detector 12 Combustion control unit 14 Abnormal combustion detector 16 Threshold selection section 18 threshold table 20 threshold 100 Combustion part 200 Control section

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-113520 (JP, A) JP-A-4-251110 (JP, A) JP-A-4-251114 (JP, A) JP-A-5- 26434 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B23N 5/12 B23N 5/18 101

Claims (5)

(57) [Claims] 1. A combustion apparatus for supplying gas fuel and air to a burner for combustion, the combustion state detecting means detecting a combustion state of a flame of the burner, and a plurality of combustion state detecting means for determining the combustion state to be abnormal. A threshold value storage means for storing a threshold value; a first combustion state detection value output by the combustion state detection means in the initial state of the apparatus; and a second combustion state detection value output when the air-fuel ratio is forcibly changed. A combustion device which compares the value with a value to identify the gas species in use, and selects a threshold value corresponding to the identified gas species from the stored plurality of threshold values; . 2. The combustion device according to claim 1, wherein the threshold value storage means is a comparison value between the first combustion state detection value and the second combustion state detection value, and the comparison value corresponding to the comparison value. A combustion device, wherein a threshold value is stored for each gas type expected to be used. 3. The combustion device according to claim 2, wherein the first combustion state detection value is a combustion state detection value when the combustion state of the burner is normal and is the best. apparatus. 4. The combustion device according to claim 1, wherein the threshold value holding unit that holds the selected threshold value, the combustion state detection value from the combustion state detection unit, and the held threshold value. And a determining means for determining an abnormality in the combustion state based on the above. 5. The combustion device according to claim 1, wherein the forcible change of the air-fuel ratio causes an excessive amount of air.