JPH0522817B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention mainly relates to a fuel method for combustors such as domestic water heaters and hot air blowers, and particularly to a proportional combustion method suitable for varying combustion capacity over a wide range. In the present invention, "proportional combustion" refers to combustion in which the combustion capacity can be changed. In addition, "air fuel ratio" is generally expressed as "air weight"/
Although expressed as "fuel weight", in this specification,
For convenience of explanation, (amount of air being supplied at that time) /
(Theoretical air amount required for the amount of fuel being burned at that time)
It is defined in This corresponds to the excess air ratio generally used in the all primary air combustion system (FIG. 6), which will be described later. In addition, in the case of the combustion method that supplies primary and secondary air (Fig. 1), which will be described later, (the amount of air being supplied at that time)/(theoretical amount of air required for the amount of fuel being combusted at that time). It means the defined primary air fraction. In this way, the "air fuel ratio"
includes the primary air ratio or excess air ratio, and is used depending on the combustion method, etc. From the viewpoint of energy saving and usability, there is a desire for a combustor that can vary its combustion capacity over a wide range depending on the size of the load. In this case, it is necessary to achieve good combustion in each combustion capacity. For this purpose, it is necessary to control the amount of air and fuel so that the air-fuel ratio in the combustion capacity becomes an air-fuel ratio that is determined by the combustor and achieves good combustion. For this purpose, various combustion methods have been proposed in the past. For example, it is called the fuel amount leading method. This method first determines the amount of fuel depending on the size of the load, detects the amount of fuel, and supplies the amount of air corresponding to the amount of fuel. Its configuration includes a proportional solenoid valve that controls the amount of fuel gas and a Bunsen burner, and determines the opening degree of the valve by controlling the amount of electricity applied to the solenoid coil of the proportional solenoid valve according to the size of the load. , the amount of fuel is varied and injected into the bench lily, and the amount of air corresponding to the amount of fuel is sucked in for proportional combustion. In addition, in the case of using a combustion blower, the amount of air is controlled in stages according to the magnitude of the load as well as the control of a proportional solenoid valve. Another example is what is called an air amount leading system. This method is the opposite of the above method, in that it controls the rotation speed of the blower according to the size of the load to determine the amount of air, detects the amount of air, and supplies the amount of fuel corresponding to the amount of air. be. Its configuration uses a zero governor as a means to detect the amount of air and determine the amount of fuel. A zero governor is equipped with a valve installed in a fuel passage and a diaphragm to which the valve is fixed, and the air pressure in the air passage is guided to the diaphragm.The valve is opened by air pressure proportional to the square of the amount of air. The system controls the fuel consumption and adjusts the amount of fuel accordingly. Further, the amount of air is detected by electrical means to determine the amount of fuel. As mentioned above, conventional systems have been used in which the air-fuel ratio is controlled to be constant. However, the air-fuel ratio may deviate from the set value due to manufacturing errors or the like. Therefore, as a means of correcting the above air-fuel ratio, the combustion state is detected using a flame rod or an _O2 sensor.
It is conceivable to correct the air-fuel ratio based on the detection result. For example, it has been known that the current value obtained by applying a voltage to a flame in a flame rod is related to the air-fuel ratio. Therefore, the current value is constantly detected, the kerosene fuel is adjusted based on the detection result, and the air-fuel ratio is thereby corrected. In addition, this item is ON-
This is OFF combustion. In addition, the flame current value changes depending on the size of the combustion capacity and the type of fuel, so in any case, the primary air ratio N ₁ (amount of air being supplied at that time/amount of fuel that is being combusted at that time) The theoretical air volume) is approximately 0.9,
It is known that the flame current value shows a peak.
Therefore, using a combustor that burns well at N ₁ ≒ 0.9,
The amount of air or fuel is corrected so that the flame current value shows the peak value, and the air-fuel ratio is adjusted to 0.9 to achieve proportional combustion over a wide range. In this case, essentially
It is constantly burned at N ₁ ≒ 0.9. Further, as the above-mentioned correction means, a combination with a zero governor has been proposed. An electromagnetic coil capable of driving a zero governor valve is provided, and the amount of electricity applied to the electromagnetic coil is controlled according to the flame current value to correct the amount of fuel. The amount of fuel is determined by the amount of current applied to the electromagnetic coil and the air pressure in the air passage applied to the diaphragm of the zero governor. Furthermore, there is a method for correcting the air-fuel ratio by detecting the peak value by measuring the radiation intensity of the flame. This is intended to achieve maximum efficiency in combustion. As described above, the following two conditions are required when the air-fuel ratio is corrected by detecting a peak value. First, it is necessary to use a combustor that achieves good combustion at the air-fuel ratio that shows its peak (N ₁ ≈0.9 for those using flame current values). However, in the case of proportional combustion depending on the load by varying the combustion capacity, it is actually difficult to obtain a combustor that burns well at the air-fuel ratio within the entire combustion capacity range. However, there was a problem that the combustor inevitably became expensive. The other one is that since the peak value is always detected, a means for accurately detecting the flame current value over the entire range of combustion capacity change (large to small) is required. That is, since the peak value of the flame current varies depending on the size of the combustion capacity, it is necessary to measure the flame current over the entire range according to the combustion capacity and find the peak value. Therefore, it is necessary to control at high speed. There was a problem that the controller was expensive. Further, when simply detecting and correcting the flame current value, in addition to the latter condition, it is necessary to store the flame current value for good combustion for each combustion capacity. For this reason, there was a problem that the memory element capacity of the controller became large, making it expensive. An object of the present invention is to provide a combustion system that makes it possible to vary the combustion capacity at low cost, without having to carry out sophisticated control such as measuring the flame current over the entire combustion capacity range and determining the peak value as in the past. The purpose is to provide a method. In order to achieve the above object, the combustion method of the present invention is a proportional combustion method in which the combustion capacity is changed by changing at least the amount of fuel, in which combustion is performed when the combustion capacity is low, and the combustion state at this time is detected by a detection means. At the same time, the fuel amount correction means corrects the fuel amount and the air-fuel ratio until the detection result by the detection means reaches the set value, and when the detection result by the detection means reaches the set value, the air amount and the fuel amount are adjusted. When supplying the amount of air and fuel corresponding to the combustion capacity required next, the amount of air and fuel stored at the time of the detected fuel capacity are used as a reference. . That is, for example, in a combustor using a zero governor, the error in the amount of fuel due to manufacturing errors is largely influenced by the zero pressure adjustment error of the zero governor. This zero pressure adjustment error pressure is determined even if the combustion amount is large and therefore the supply pressure to the fuel metering orifice is large, and even if the combustion amount is small and therefore the supply pressure to the fuel metering orifice is small. , their absolute values are almost the same. Since the amount of fuel supplied is proportional to the square root of the supply pressure, the ratio of error to the set value of the fuel amount increases when the fuel capacity is small. Therefore, in the present invention, a zero governor configured to electrically correct the zero pressure adjustment of the zero governor based on the flame current, which is an index of good combustion, is installed, and combustion is performed in the area with low combustion capacity, resulting in good combustion. The zero governor pressure is corrected so that the correction value is maintained regardless of the combustion capacity, and there is no need to perform correction work using flame current for other combustion capacities. Hereinafter, a description will be given of FIGS. 1 and 2 showing an embodiment of the present invention in which a zero governor is used. In the figure, 1 is a proportional combustion burner, which is formed linearly in the depth direction. Also burner 1
has a secondary air passage 2 in the center, and a large number of slit-shaped secondary air ports 3 are arranged in parallel in the depth direction at the top thereof. On both sides thereof, a large number of slit-shaped flame ports 4 are arranged in parallel in the depth direction. A premix passage 6 is provided between the outside of the burner 1 and the wall 5.
Heat is removed from the combustion gas by the heat exchanger 8, and the exhaust port 9
is discharged from. The heat exchanger 8 is a once-through type water passage 8
a and an endothermic fin 8b. Water entering the heat exchanger 8 from the water inlet 11 becomes hot water and flows out from the outlet 12. The hot water temperature is detected by the temperature sensor 13, and the rotation speed control means 14a of the control device 14 controls the rotation speed of the combustion blower 15. That is, when the hot water temperature is higher than the predetermined temperature, the rotation speed is decreased. Air for combustion is provided by blower 15
Some of the air is blown from the secondary air passage 17 to the secondary air passage 2 of the burner 1.
is supplied to The remaining air is supplied to the bench lily 18. A fuel supply nozzle 20 is opened in the constricted portion of the bench lily 18. Reference numeral 21 denotes a zero governor, which controls the amount of fuel supplied through the fuel inlet 22 to a fuel amount corresponding to the amount of combustion air.
6 to the fuel nozzle 20. Zero governor 21 is used to match the amount of fuel to the amount of air.
The pressure of the air supply passage 16 is applied to the air supply passage 16 through a pressure transmission pipe 23. 14b is a fuel amount correction means;
The flame rod 28 detects the minimum value of the electrical resistance of the flame (that is, the peak value in terms of flame current value. Hereinafter referred to as the peak value), the detection result is calculated by a microcomputer, and the The opening degree of the valve of the zero governor 21 is controlled by adjusting the current value given to the moving coil 45. The flame rod 28 detects the minimum value of the electrical resistance of the primary flame (that is, the peak value in terms of flame current value. Hereinafter, also referred to as the peak or peak value), and detects the opening of the valve of the zero governor 21. control. Flame rod 28 is located in the wake of the primary flame. The electrical resistance value of the flame is detected by applying a voltage between the flame rod 28 and the burner 1. Fuel amount correction means 14b and rotation speed control means 14
and a are mutually related as shown in FIG. 3, which will be described later. Further, the control device 14 having the fuel amount correction means 14b and the rotation speed control means 14b includes a microcomputer that performs arithmetic processing, and a frame rod 8.
It consists of peripheral equipment that performs current input to the zero governor 21 and fuel blower 15. FIG. 2 shows details of the zero governor 21. The outer periphery of the flexible diaphragm 33 is attached to the main body 3.
The diaphragm 33 is airtightly fixed between 1 and 32.
A control pressure chamber 34 is formed on one side, and a control pressure chamber 34 is formed on the other side.
A secondary pressure chamber 36 is formed. A valve 35 is provided on the diaphragm 33 and divides the fuel passage into a primary pressure chamber 36 and a controlled pressure chamber 37. The valve 35 is fixed with a spring 38 and a pin 39. 40 is a backing plate. The main bodies 31 and 32 are made of non-magnetic material. 42 is a lid fixed airtightly. 43 is a connection port of the pressure transmission pipe 23. Reference numeral 45 denotes a moving coil, in which a thin insulated copper wire is wound around a cylindrical bobbin 46 fixed to the backing plate 40. Both ends of the moving coil 45 are connected to the fuel amount correction means 14b via a terminal plate 47 provided on the side surface of the main body 32. The terminal plate 47 is airtightly fixed to the main body 32. The bobbin 46 is made of a non-magnetic material such as paper or aluminum. After being fixed to the valve with the pin 39, the bobbin 46 is fixed to the backing plate 40 by adhesive or the like. 48 is an annular permanent magnet magnetized in the vertical direction, 49 is a magnetic yoke located on the lower surface of the permanent magnet 48, and a magnetic center pole 50 that fits into the bobbin 46 is provided at the center. Reference numeral 51 denotes a yoke plate made of a magnetic material and configured in an annular shape, located on the upper surface of the permanent magnet 48. A predetermined distance is provided between the center pole 50 and the bobbin 46 and between the moving coil 45 and the yoke plate 51, and a magnetic field is provided between the center pole 50 and the yoke plate 51. Reference numeral 55 denotes a lid that is fixed airtight and is made of a non-magnetic material. Lid 5
5. The yoke 49, the permanent magnet 48, and the yoke plate 51 are sequentially fixed with adhesive. When a direct current is passed through the moving coil 45, an upward force proportional to the amount of current is generated. This force corresponds to the push-up force of a pressure regulating spring for setting the pressure of a conventional general zero governor. The operation of such a configuration will be explained. When the blower 15 is operated, the pressure of the combustion air increases the pressure in the control pressure chamber 34, and this pressure and the pushing force of the moving coil 45 cause the diaphragm 3 to rise.
3 is pushed up. Valve 35 opens and fuel inlet 22
Fuel (gas) flows into the controlled pressure chamber 37 from below. When the pressure in the controlled pressure chamber 37 increases, the valve 3
5 is pushed down, the amount of fuel flowing into the controlled pressure chamber 37 decreases, and the pressure in the controlled pressure chamber 37 becomes low. At this time, since the effective diameter of the diaphragm 33 and the effective diameter of the valve 35 are configured to be equal, the forces generated by the inlet pressure cancel each other out. Therefore, the force that the diaphragm 33 receives from the control pressure chamber 34 side and the force that the diaphragm 33 receives from the controlled pressure chamber 3 side
The pressure in the controlled chamber 37 is maintained so that the forces applied to the diaphragm 33 from the 7 side through the valve 35 are balanced. Fuel is supplied at this pressure, and the orifice 26
The flow rate of the fuel flowing out is adjusted and the fuel is supplied from the fuel nozzle 20 to the vent lily 18. The fuel and air supplied to the bench lily 18 become a premixture, flow out from the flame port 4 through the premixture passage 6, and undergo primary combustion. The secondary air passes through the secondary air passage 17-2, flows out from the secondary air port 3, and is subjected to secondary combustion. The rotation speed control means 14a detects the hot water temperature at the outlet 12 of the heat exchanger 8 with a temperature sensor 13, and applies a current to the blower 15 at a rotation speed corresponding to the required combustion capacity based on the difference from the set temperature. Output. on the other hand,
As shown in FIG. 3, the fuel amount correction means 14b detects the combustion state at the flame rod 28 only at the time of ignition, controls the current value to the moving coil 35,
Change the push-up force and correct the air-fuel ratio. Thereafter, the current value is maintained and does not change even if the required combustion capacity changes. That is, the air-fuel ratio is compensated by the above-mentioned held current value. Therefore, under normal conditions, the amount of air blown increases or decreases based on the output of the rotational speed control means 14a, and the pressure in the control pressure chamber 34 changes, thereby changing the opening degree of the valve 35, and the amount of fuel corresponding to the amount of air blown changes. quantity is supplied,
Proportional combustion. Next, the operation of the control device 14 will be explained in detail. As shown in FIG. 4, the electrical resistance value of the flame varies depending on the type of fuel and combustion capacity even if the primary air ratio is constant. However, the tendency of increase and decrease is similar, and moreover, the flame resistance value is the minimum value 1
The sub-air ratio N ₁ is constant and approximately 0.9. When a combustion command is given, after pre-purging, as shown in FIG. (both not shown) is turned on, and a large voltage is set in advance so that the primary air ratio _N1 is 0.9 or less.
V ₀ is supplied to the moving coil 45 by the fuel amount correction means 14b. The amount of fuel at this time is F ₀ , and the fuel is rich. When the flame rod 28 detects ignition, the igniter is turned off, and the flame resistance value R ₀ at this time is detected and stored by the fuel amount correction means 14b. Figures 4 and 5
The flame resistance at this time is indicated by the number 0 in the figure.
In this case, since ignition is performed with N ₁ small,
Good ignition. Next, the voltage applied to the moving coil 45 is set to (V ₀ -V ₁ ) and lowered slightly. The lowering amount _V1 is determined in advance. By this, moving coil 4
The pushing force of the valve 35 decreases, the opening degree of the valve 35 decreases, and the fuel amount decreases a little (F ₀ −F ₁ ).
Therefore, the primary air ratio increases a little, resulting in the state numbered 1 in FIGS. 4 and 5. Next, the flame resistance value R ₁ of combustion based on this amount of fuel is measured, stored, and compared with the previously stored flame resistance value R ₀ . If R ₀ > R ₁ , proceed to the next step and (V ₀ −
V ₂ ) is set, the applied voltage is further reduced, and a smaller amount of fuel (F ₀ −F ₂ ) is supplied.
Measure and store the flame resistance value _R2 . Compare R ₁ and R ₂ , and if R ₁ <R ₂ , return, set an even lower applied voltage (V ₀ −V ₃ ), and repeat the above operation. Here, Rn is the latest flame resistance value, and Rn _-1 is the previous flame resistance value. If Rn _-1 <Rn, it can be said that the primary air ratio is around 0.9. In Figures 4 and 5, as shown by number 3, the flame resistance increases at the third time, and Rn _-1 < Rn
It shows that it has become. Therefore, using the applied voltage (V ₀ −Vn) at this time as a reference, a voltage (J ₀ −Vn−Vk) that is obtained by further subtracting the preset voltage Vk is applied to the moving coil 45 (number 4). Therefore, the fuel amount is even smaller (F ₀ −Fn−Fk)
Therefore, the primary air ratio N ₁ becomes even larger. The primary air ratio N ₁ in this state is set to N ₁ that provides the best combustion. Then, the applied voltage (V ₀ −Vn−Vk) is held thereafter. To be more specific, the control device 14 measures, by an analog/digital converter, the voltage appearing across a resistor inserted in series in a circuit including the flame rod 28 to which the voltage is applied. The current flowing through the flame is calculated using Ohm's law, and the resistance R is determined from the calculated current value and applied voltage using Ohm's law. The output portion of the control device 14 to the zero governor 21 and the combustion blower 15 converts the calculation result of the microcomputer into a current value using a digital/analog converter and a current amplifier and outputs the result.
Note that these calculation parts are operated by software programmed into a microcomputer.
Further, the voltage Vk is an applied voltage correction amount determined in advance to achieve good combustion based on the voltage applied to the zero governor at which the flame resistance reaches its peak value. Next, an output is made to the rotational speed control means 14a so as to supply an amount of air with a combustion capacity corresponding to the magnitude of the load. Thereafter, the amount of fuel will be supplied in proportion to the air pressure based on the amount of air. An example will be explained in detail. The specifications of the burner 1 used are as follows. Maximum combustion capacity:
Minimum combustion capacity: 4200kcal/h from 26000kcal/h
Proportional combustion is possible. That is, it can vary from 1/1 to 1/6.2. The good combustion range (evaluated by CO/CO ₂ values, etc.) is determined by the primary air ratio N ₁ and excess air ratio n
When expressed as (air supply amount/theoretical air amount), N ₁ = 0.85 to 1.5 at the minimum combustion capacity, n =
1.8-3.3, N ₁ = 0.62-1.35 at maximum combustion capacity,
n=1.3 to 2.8. The good combustion range of intermediate combustion capacity lies in between. Also, N ₁ ≒ 0.9, which shows the peak value at the minimum combustion capacity, is approximately
It is 1.9. Therefore, it is designed to ignite with the minimum combustion capacity, and at that time (when the fuel amount is F ₀ ), N ₁₀ ≒ 0.7,
n≒1.5, when detecting and holding the peak (when the fuel amount is (F ₀ −Fn−Fk)), N ₁ set≒1.2, nset≒
Set it to 2.6. Of course, the values of M ₁ set and n set should be set within the good combustion range of the minimum combustion capacity, but they should also be taken together to ensure good combustion in combustion above this combustion capacity and at the maximum combustion capacity. stipulate. That is, N ₁ set and n set
The value of is determined based on this value so that combustion within the range of the combustion capacity that must be carried out is good. This burner is premixed, so
The primary air ratio _N1 is determined more than the excess air ratio n. Also, change in fuel amount - Detection of flame resistance - Comparison 1
Set the step to 0.8 seconds. Also, the fuel reduction rate by one step is N ₁ ≒
It is 0.035. According to this, N ₁ set, with about 6 steps on average,
n set, and at maximum combustion capacity N ₁
can be reduced from approximately 0.8n to approximately 1.6, and even at the minimum combustion capacity, N ₁ can be reduced to 1.18 to 1.33 even under various conditions.
n could be set to 2.5 to 2.8, and good combustion could be achieved at each combustion capacity. Also, the type of fuel gas
13A-O, C ₃ H ₈ and 6B-O were all tested successfully. Incidentally, even if poor combustion occurs until the voltage of (F ₀ -Fn-Fk) is set, it is acceptable because it will only last for a short time. Reducing the combustion capacity also reduces the flame current, so
Detecting the entire range from the maximum combustion capacity to the minimum combustion capacity would require expensive detection means, but in the present invention, the air-fuel ratio is corrected by detecting only a part of the combustion capacity, and other combustion capacities are based on this. , which can be done at low cost. Furthermore, since the peak value is detected and the air-fuel ratio is set based on this peak value to ensure good combustion in the burner, combustion can be performed at an air-fuel ratio suitable for the burner. In the above embodiment, the applied voltage correction amount Vk is determined so that N ₁ set is larger than 0.9, but in the case of a combustor with good combustion smaller than N ₁ set = 0.9, N set is set so that N 1 set is larger than 0.9. Vk to
may be set to a negative value. Further, in those using a zero governor (conventional zero governors use a pressure regulating spring instead of the moving coil 45, etc.), the error in the air-fuel ratio on the low combustion capacity side is generally large, which tends to cause poor combustion. Therefore, in the present invention, the minimum combustion capacity with a large air-fuel ratio error is checked and corrected. In the embodiments described above, the zero governor setting operation was performed at the initial stage of ignition, but in devices that operate continuously for a long time, such as a space heater or a water heater for hot water heating, the setting operation may be performed at certain time intervals. By doing so, it is possible to eliminate the influence of some kind of disturbance that occurs over a long period of time. In addition, for instant water heaters, even if combustion stops when the set temperature is reached (V ₀
-V ₂ -Vk) is memorized, and in the case of re-ignition within a predetermined time or while the flow switch is ON, it immediately outputs (V ₀ -Vn-Vk) and performs the setting operation. It is also possible to shorten the time and improve responsiveness. Further, in the above description, the value of N ₁ set is set to be larger or smaller than 0.9, but it can also be used for a burner that burns well when N ₁ ≈0.9 by setting N ₁ set = 0.9. Furthermore, during steady combustion, the voltage applied to the moving coil set at the time of ignition can be corrected based on signals such as the magnitude of the load. Further, in the above embodiment, the air is supplied after being divided into primary air and secondary air, but it can also be applied to an all-primary system. This will result in incomplete combustion when ignited. In addition, in the above embodiment, the detection point (N ₁ ≒0.9) is determined using the characteristic indicating a peak, but N ₁ ≒0.9
Determine the detection value in the shaded area on the left or right side of
This may be used as a detection point. Note that the above is a special case where Vk is approximately 0. Further, in the embodiment described above, the correction is made using the minimum combustion capacity, but the correction may be made using a combustion capacity larger than that in relation to the flame current value, etc. Furthermore, flame radiation intensity or the like can also be used as the detection means. Other means will be explained with reference to FIGS. 6 to 8. In this embodiment, an O ₂ sensor is used as a means for detecting the combustion state. In FIG. 6, burner 60
uses a fully linear equation. 61 is the _O2 sensor,
Located in the wake of the flame. The O ₂ sensor 61 is made of zirconia or the like. The output characteristics of the O ₂ sensor 61 are as shown in FIG. 8, and hardly change depending on the type of fuel, and the output is determined when the air ratio N (air amount/theoretical air amount) is determined. However, the tendency of increase and decrease in the output suddenly changes around the air ratio N=1.0, and when N is smaller than this, the output is higher than a certain threshold Vs, and when N is larger, the output becomes smaller than Vs. FIG. 7 shows the program of the control device 14. The rest of the structure is the same as the embodiment shown in FIGS. 1 and 2. The correction operation of such a configuration will be explained. At the time of ignition, the amount of air near the minimum combustion capacity is supplied, and the air rate N is
A voltage V ₀ preset to be smaller than 1.0 is applied to the moving coil 45. The output state of the O ₂ sensor 61 in this state is indicated by the number 0 in FIG. When ignited, the output of the O ₂ sensor is compared with a preset threshold value Vs, and the O ₂
Moving coil 45 when the sensor output is large
Reduce the voltage applied to. In this way the _O2 sensor output becomes smaller than the threshold Vs (number 3
state), then reduce and hold the predetermined voltage Vk. The following is the same as the above example.
Measurements are taken after the rise time of the _O2 sensor has elapsed. According to the means using the present O ₂ sensor, the same effects as in the above embodiment can be obtained. Further, since it has a threshold value, the set N (N≈1.0) can be detected accurately and easily. Even if the O ₂ sensor output changes depending on the combustion capacity, it is only necessary to set the threshold value for a certain combustion capacity, so this can be done easily. As described above, since the present invention detects only a part of the combustion capacity, it can be configured at low cost.

[Detailed description of the invention]

Fig. 1 is an overall configuration diagram of an embodiment of the present invention, Fig. 2
The figure is a longitudinal sectional view of a zero governor according to an embodiment of the present invention.
FIG. 3 is a flowchart of a control device according to an embodiment of the present invention, FIG. 4 is a diagram showing characteristics of flame resistance, and FIG.
The figure is an explanatory diagram of control according to one embodiment of the present invention, and FIG. 6 is a vertical sectional view of the main part of a burner according to another embodiment of the present invention.
Figure 8 is a diagram showing the output characteristics of the O ₂ sensor, Figure 7
The figure is a flowchart of a control device according to another embodiment of the present invention. 1...burner, 3...flame port, 4...secondary air port, 8...
Heat exchanger, 12... Outlet, 13... Temperature sensor, 1
4...control device, 14a...rotation speed control means, 14b
...Fuel amount correction means, 15...Blower, 18...Bench lily, 20...Fuel nozzle, 21...Zero governor, 2
2...Fuel inlet, 25...Fuel outlet, 28...Frame rod, 33...Diaphragm, 45...Moving coil, 46...Bobbin, 48...Permanent magnet, 49...
Yoke, 51... Yoke plate, 60... Burner,
61... _O2 sensor.

Claims (1)

[Scope of Claims] 1. In a proportional combustion method in which the fuel capacity is changed by changing at least the amount of fuel, combustion is performed when the combustion capacity is low, the combustion state at this time is detected by the detection means, and the combustion state is detected by the detection means, and the fuel amount correction means is used. The air-fuel ratio is corrected by correcting the fuel amount until the detection result by the detection means reaches the set value, and when the detection result by the detection means reaches the set value, the air amount and fuel amount are memorized and the air-fuel ratio is A proportional combustion method, characterized in that when supplying an air amount and a fuel amount corresponding to a combustion capacity, the air amount and fuel amount are supplied based on the air amount and fuel amount stored at the time of the detected fuel capacity. 2. In claim 1, the detection means is such that a detected value indicates a peak value or a minimum value at a predetermined air-fuel ratio in a combustion range, and the set value is set to the peak value or minimum value. A proportional combustion method characterized by: 3. In claim 1, the detection means is characterized in that a detected value indicates a threshold value at a predetermined air-fuel ratio in a combustion range, and the set value is set to the threshold value. Proportional combustion method. 4. The proportional combustion method according to claim 1, wherein the low combustion capacity time is set at the time of ignition. 5. In claim 1, the detected value is determined by the combustion performance of a combustor set so that the air amount and fuel amount indicating the set value are increased by a predetermined amount, that is, the air-fuel ratio is increased. A proportional combustion method characterized in that the amount is added or subtracted from the amount.