JPS616514A - Automatic controlling device for combustion amount of burner - Google Patents

Abstract

PURPOSE:To restrain faulty fire extinguishment caused by adhesion of dust, dirt and tar upon weak combustion and obtain the stabilized combustion heat at all times by a method wherein supplying amount of the fuel is increased by constant amount, when a flame current comes to the value of fire extinguishing current as a lower limit, in which the fire is to be extinguished. CONSTITUTION:The flame current inputted into an A/D input terminal from a flame sensor circuit 2 is read. In case the read value exceeds the value of a fire extinguishing current I, the combustion is decided as a normal combustion and next flame current I is read. In case the flame current I is under the fire extinguishing current I, the combustion is decided that the flame 14 become small due to some reason and the output level of an output terminal 03 is returned to L level and the output level of an output terminal 02 becomes H level, then, a contact 8a is opened and contact 7a is closed, therefore, the supplying amount of the fuel from a fuel pump 12 is changed to a middle (weak) range. In case the flame 14 of normal shape can not be obtain by the adhesioning dust, dirt and tar, the supplying amount of the fuel from the fuel pump 12 is increased through a pump driving circuit 11 stepwisely until obtaining the normal shape flame 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a combustor, and more particularly to a combustion amount adjustment device 17I of a combustor that utilizes flame current output from a flame sensor.

[Technical Background of the Invention and Problems Therewith] For example, some combustors used as household heaters are equipped with a flame sensor that detects the burnup of the flame in the burner. This flame sensor detects that when a pair of electrodes is inserted between the outer flame and the inner flame and an alternating current voltage is applied between the electrodes, a direct current flows between the outer flame and the inner flame due to the rectifying effect of the flame. The value of this direct current, or flame current, depends on the combustion state of the flame.For example, when the flame becomes small or red, the flame current decreases.Also, the value of the flame current decreases when the flame becomes small or red. Even if the flame current decreases, the flame current will decrease.When the flame goes out, the flame current will naturally become zero.

Then, by detecting the flame misfire state or a drop in oxygen concentration from the value of the flame current output from this flame sensor, it is possible to perform extinguishing operations for the entire combustor, such as stopping the primary bomb in the event of a misfire, or to control the oxygen concentration. A room ventilation warning is automatically executed when the ventilation level decreases.

However, the combustor that detects abnormal combustion using the flame sensor as described above has the following problems. In other words, in general, in the heating combustor described above, the combustion amount is adjusted to correspond to the season and ambient temperature, for example, [strong].
It is configured so that it can be set to two types: [Weak]. However, generally during strong combustion (e.g. 3300 Kc
al/h) and during weak combustion (e.g. 1100 Kcal/h)
h), there is a large difference in the combustion amount between the normal flame current value when the combustion amount is set to [weak] and the preset flame current value that determines that the above abnormal combustion has occurred in the flame. The difference from the lower limit of current becomes smaller. Therefore, during operation of the combustor, dust, 11. If tar, etc. adheres to the burner and the amount of combustion is slightly lower than the specified value, the flame will also become slightly smaller. Therefore, the flame current also decreases in response to changes in the state of the flame, and decreases below the lower limit value, increasing the probability that combustion will be extinguished or a ventilation warning will be output. Normally, such a state is not considered a malfunction and can be canceled by switching the combustion amount to [strong], but on the other hand, when the combustion amount is set to [weak], erroneous extinguishing becomes a problem.

[Object of the Invention] The present invention was made based on the above circumstances, and its purpose is to increase the amount of fuel supplied by a constant amount when the flame current reaches the lower limit value for extinguishing. By doing so, it is possible to suppress accidental extinguishing during weak combustion, and
An object of the present invention is to provide an automatic combustion amount adjustment device for a combustor that can always obtain stable combustion heat.

[Summary of the Invention] In the combustor combustion amount automatic adjustment device of the present invention, when the flame current output from the flame sensor that detects the burn-up of the flame in the burner falls below a preset lower limit value for extinguishing. When the fuel supply amount in the fuel pump is increased by a preset constant amount until the flame current exceeds the lower limit value, the flame current increases when the increased fuel supply amount reaches the preset upper limit value. The combustor extinguishing command is output only when the current drops below the lower limit value.

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit configuration diagram showing an automatic combustion amount adjustment device for a combustor according to an embodiment, and numeral 1 in the figure indicates various calculation circuits.

Command register, internal storage, A/D conversion circuit.

It is a microcomputer consisting of a single electronic component with a built-in input/output board, etc. This microcomputer 1
The flame sensor circuit 2 is connected to the A/D input terminal of 01. Driver 3 in '02 and 03 respectively
．． 4. -5 to one end of each relay L6.7.8. The other end of each of these relays 6.7.8 is commonly connected to a DC +Vc power supply terminal. In addition, the input terminal $1 and the input terminal S2 are connected to respective terminals of a changeover switch 9 attached to the operation panel as a combustion amount setting means for switching the combustion amount between two types: U strong and U weak. The common terminal of the changeover switch 9 is connected to + via the resistor 10.
It is connected to the Vc power supply terminal.

One end of each contact 5a, 7a, 3'a, which is controlled to open and close by each relay 6.7.8, is connected to each input terminal A1. A2. A3, and the other end is commonly connected to the output terminal G.

A fuel pump 12 is connected between output terminals 01 and 02 of the pump drive circuit 11 for supplying fuel to the combustion chamber. Then, when the relay 6 is activated and the contact 6a is closed, the pump drive circuit 11 switches the selector switch 9 to the [strong] position, for example.
The rotational speed of the fuel pump 12 is controlled so as to supply fuel corresponding to a combustion amount of 3300 Kcal/h to the combustion chamber. Similarly, when relay 8 operates and contact 8b closes, 1100 Kcal/h of fuel corresponding to [weak] is supplied via fuel pump 12, and relay 7 operates and contact 7a closes. When it is [strong [weak] middle 2200K
Cal/h of fuel is supplied.

As shown in the figure, the flame sensor circuit 2 is a circuit that detects a flame current I flowing between an outer flame 15 and an inner flame 16 of a flame 14 in a burner 13 of a combustion chamber. When the output voltage of the AC power source 17 is applied via the resistor 18, 19 and the capacitor 20, 21 between the outer flame 15 of the flame 14 and a pair of electrodes inserted into the conductive burner 13, the voltage is applied in the direction of the arrow in the figure. A current flows, this current is converted into a voltage value by a resistor 22, and is inputted to the A/D input terminal of the microcomputer 1 as a flame current I.

In addition to the control program, the internal storage section of the microcomputer 1 also contains information on how to extinguish the combustion if the flame 14 becomes smaller or becomes a red flame and abnormal combustion occurs and this state continues. The extinguishing current value IL is stored as the lower limit value of the determined flame current (■).

When the power to the combustor is turned on and the selector switch 9 is set to "low low", the microcomputer 1 sends an H level signal to the driver 5 from the output terminal o3. Then, the relay 8 operates and the contact 8a is closed. When the contact point 8a is closed, a rotational drive signal is sent from the pump drive circuit 11 to the fuel pump 12 so as to supply fuel corresponding to 1100 Kcal/h.

Then, when the fuel is ignited in the burner 13 and a flame 14 is formed as shown in the figure, the microcomputer 1
The fuel pump 12 is configured to control the fuel supply amount of the fuel pump 12 according to the flow chart shown in the figure.

That is, when the program is started, the flame current ■ input from the flame sensor circuit 2 to the A/D input terminal is read at Pl. Next, it is checked whether the read flame current I exceeds the extinguishing current IL stored in the internal storage section. If the extinguishing current ■L is exceeded, it is determined that combustion is normal and the process returns to Pl to read the next flame current ■. When the flame current I is less than the extinguishing current IL, it is determined that the flame 14 has become smaller due to some factor, and the output level of the output terminal 03 is returned to the L level,
The output level of output terminal 02 is set to H level.

Then, the contact point 8a is opened and the contact point 7a is closed, so that the amount of fuel supplied from the fuel pump 12 becomes [weak] 1100.
Kcal t+Kau intermediate (7) 2200 Kcal/
changed to h.

When the combustion feed bed is increased to 2200 Kcal/h,
If there is no particularly serious failure in the burner 13 section, the flame 14 will naturally become larger, and therefore the flame current I detected by the flame sensor circuit 2 will also increase. The flame current I is read from the A/D input terminal and compared again with the extinguishing current IL. And flame current■
If exceeds the extinguishing current IL, it is determined that the combustion state is normal and the process returns to the initial Pl. When the flame current I is less than the extinguishing current ■L, it is determined that the flame 14 is still small, and the output level of the output terminal 02 is returned to the L level, and the output level of the output terminal 01 is changed to the H level. As a result, the amount of fuel supplied from the fuel pump 12 increases from 2200Kcal h to 3
Forcibly switch to the [strong] state of 300 Kcal/h.

Thereafter, the flame current I @ input to the A/D input terminal is read again and compared with the extinguishing current IL. As a result, when the flame current I exceeds the extinguishing current IL, it is determined that combustion is normal and the process returns to Pl to read the next value of the flame current I. Note that even in the state where 3300 K cal/h of fuel is being supplied, which indicates this [strong] combustion state, the flame current ■ is higher than the extinguishing current I.
If it is less than L, it is determined that some serious abnormal phenomenon has occurred, and all output terminals 01. A fire extinguishing command is output that sets the output level of O'2.03 to L level. As a result, the fuel pump 12 is stopped and the fuel supply to the burner 13 of the combustor is cut off, so that the flame 14 is extinguished and combustion is extinguished.

With the combustor combustion m automatic 1111 adjustment device configured in this way, dust, dust, tar, etc. can be prevented from entering the burner 13 etc. even when the proper amount of fuel is being supplied from the fuel pump 12. If the flame 14 of a normal shape cannot be obtained due to adhesion, the flame sensor circuit 2 detects this condition. Then, the amount of fuel supplied to the fuel pump 12 is increased in stages via the pump drive circuit 11 until a flame 14 with a normal shape is obtained.

Therefore, the supply amount of the fuel pump 12 is fixed when the shape (size) of the flame 14 becomes almost constant, so even if the user of this combustor initially sets the changeover switch 9 to [Low]. , the amount of fuel supplied is automatically adjusted so that the size of the flame 14 is approximately constant. As a result, stable combustion heat can always be obtained.

Furthermore, when the flame current ■ becomes less than the extinguishing current IL, the fuel supply amount is increased sequentially, and when the fuel supply amount reaches a predetermined upper limit of 3 300 kc/h, the flame current ■ continues to increase. The combustor extinguishing command is output only when the extinguishing current value It is less than or equal to the extinguishing current value It. Therefore, it is possible to suppress erroneous extinguishing caused by adhesion of dust, dust, tar, etc. when the combustion amount is set to [weak].

Note that if the flame 14 becomes smaller due to a decrease in the oxygen concentration around the flame 14 and the flame current I falls below the extinguishing current IL, the flame current I will hardly increase even if the fuel supply amount is sequentially increased. .

Therefore, by detecting the amount of change in flame current I, it can be confirmed that the oxygen concentration has decreased.

FIG. 3 is a flowchart showing the operation of an automatic combustion amount adjustment device for a combustor according to another embodiment of the present invention.

Note that the circuit configuration diagram of this embodiment is the same as that in FIG. 1, so a description thereof will be omitted.

In this embodiment, similarly to the previous embodiment, the flame current ■ is read at P2, and the read flame current I is equal to the extinguishing current IL.
If it is below, reduce the fuel supply amount from 1100Kca+/h to 2
Increase the flame current I to 200 Kcal/h and compare the flame current I and the extinguishing current IL again. Then, the flame current I is the extinguishing current I
When it exceeds L, the process returns to P2, but the flame current I becomes the extinguishing current I.
If it is less than L, a fire extinguishing command is immediately output without increasing the fuel supply amount.

Even with the 1 llvA combustion rate adjustment device configured in this way, the frequency of erroneous extinguishing caused by adhesion of dust, dirt, tar, etc. that occurs when the combustion rate is set to [weak] is reduced. It is possible to achieve the original purpose.

FIG. 4 is a circuit configuration diagram showing an automatic combustion amount adjustment device for a combustor according to still another embodiment of the present invention, and the same parts as in the embodiment of FIG. 1 are given the same reference numerals. Therefore, the explanation of the overlapping parts will be omitted.

Output terminal o1 of microcombi 1-31 in this embodiment
is connected to one end of a light emitting diode 33a of a photocoupler 33 via a resistor 32, and this light emitting diode 33a
The other end is grounded.

Both terminals of the phototransistor 33b of the photocoupler 33 are connected to each input terminal A of the pump drive circuit 35 of the fuel pump 34.
1. It is input to A2.

The pump drive circuit 35 is configured to control the rotation of the fuel pump 34 at a rotation speed corresponding to the frequency F of the pulse signal sent from the output terminal 01 of the microcomputer 31 via the photocoupler 33. That is, when the microcomputer 31 outputs a high frequency pulse signal from the output terminal 01, the amount of fuel supplied to the burner 13 increases, and when the frequency is lowered, the amount of fuel supplied also decreases.

In addition to the extinguishing current value IL, the internal memory of the microcomputer 31 also contains the combustion amount [weak] <1100Kca.
Frequency Fm1n corresponding to the fuel supply amount of l/h), frequency 1"max corresponding to the combustion I [strong] (3300KCa1/1)), and fuel supply amount of, for example, 100 K.
Frequency ΔF corresponding to 100 Kcal/h for increasing by caVh, etc. are stored.

Then, the power to the combustor is turned on and the selector switch 9 is set to [
[Weak], the microcomputer 31 outputs a pulse signal of frequency F mim from the output terminal o1. Then, the pump drive circuit 35 operates and the fuel pump 34 rotates at a rotational speed corresponding to the input frequency Fm1n. Therefore, 1100 K from the fuel pump 34
Fuel corresponding to cal/h is supplied to the burner 13.

When the fuel is ignited in the burner 13 and a flame 14 is formed as shown, the microcomputer 31 is configured to control the fuel supply amount of the fuel pump 34 according to the flowchart shown in FIG. That is, first, the output frequency F is initialized to the minimum value F min. Next, at P3, a pulse signal of frequency F is output from output terminal 01. and,
In this state, read the flame current I input from the flame sensor circuit 2 to the A/D input terminal. The read flame current I and the extinguishing current It are compared, and when the flame current I exceeds the extinguishing current It, it is determined to be normal and the process returns to P3 to read the next flame current 1. When the flame If flow I is less than the extinguishing current IL, add a frequency ΔF equivalent to 100 Kcal/h to the frequency F, and then confirm in P4 that the added frequency F does not exceed the upper limit frequency FIIlax. After confirmation, return to P3 and output the added frequency F to terminal 0.
1 to the pump drive circuit 35 via the photocoupler 33. Then read the flame current I again and extinguish current IL
Compare with.

When the frequency F exceeds Fmax at P4, the fuel supply amount of the fuel pump 34 becomes [330C>Kcal/
Since the flame current I is still below the extinguishing current IL even after exceeding h, it is determined that some serious abnormal phenomenon has occurred, and the frequency F of the pulse signal output from the output terminal 01 is set to O. As a result, the fuel pump 34 stops and the burner 13
Since the fuel supply to is cut off, the flame 14 is extinguished and the combustion is extinguished.

Even in the automatic combustion amount adjustment device for the combustor configured in this way, when the flame current I becomes equal to or less than the extinguishing current IL, the fuel supply amount increases sequentially by, for example, 100 k cat/h. It is possible to obtain similar effects.

Particularly in this embodiment, since the amount of increase in fuel supply amount per time when the flame N flow becomes less than the extinguishing current IL can be arbitrarily changed by program setting, the amount of increase per time can be set small. By doing so, even smoother automatic adjustment of combustion heat can be carried out.

[Effects of the Invention] As explained above, according to the present invention, when the flame current reaches the extinguishing current value as the lower limit value for extinguishing, the amount of fuel supplied is increased by a constant amount. Therefore, it is possible to suppress erroneous extinguishing caused by adhesion of dirt, dust, tar, etc. during weak combustion, and to always obtain stable combustion heat.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing an automatic combustion amount adjustment device for a combustor according to an embodiment of the present invention, FIG. 2 is a flowchart showing the operation of the automatic combustion amount adjustment device, and FIG. FIG. 4 is a flowchart showing the operation of an automatic combustion amount adjustment device for a combustor according to another embodiment of the present invention; FIG. 5 is a circuit diagram showing an automatic combustion amount adjustment device for a combustor according to yet another embodiment of the present invention is a flowchart showing the operation of the combustion amount automatic adjustment device. 1.31... Microcomputer, 2... Flame sensor circuit, 6.7.8... Relay, 9... Changeover switch, 11.35... Pump drive circuit, 12.34...
・Fuel pump, 13...burner, 14...flame, 15
...Outer flame, 16...Inner flame, 17...AC power supply, 3
3...Photo coupler. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] In a combustor in which a burner combusts fuel supplied through a fuel pump that is driven and controlled in accordance with a combustion amount set by a combustion amount setting means, the burn-up of the flame in the burner is A flame sensor detects the burnup of the flame by detecting the flame current flowing between the outer flame and the inner flame of the flame, and the flame current output from this flame sensor decreases below a preset lower limit value for extinguishing. an increasing means for sequentially increasing the amount of fuel supplied by the fuel pump by a preset constant amount until the flame current exceeds the lower limit; and the amount of fuel supplied by the increasing means is set in advance. and means for outputting an extinguishing command for the combustor when the flame current decreases below the lower limit when the flame current reaches the upper limit.