JP3098143B2 - Combustor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustor for quickly changing an air-fuel ratio to a target value in response to a new set temperature change command during air-fuel ratio correction.

[0002]

2. Description of the Related Art Conventionally, the calorific value of a combustor such as a water heater or a fan heater is determined by changing a calorific value setting means (for example, a temperature setting means) set by a user. The combustion is controlled so as to quickly correspond to the supply amount of combustion air from the blower. To do this, as shown in FIG.
In step 1, a calorific value is calculated as a target control amount based on the measured hot water temperature of the temperature sensor 23 and the set temperature of the hot water temperature setting device 61, and the proportional valve control is performed in accordance with the calorific value which is the setting state of the calorific value setting circuit 81. The circuit 43 controls the amount of fuel supplied by the proportional control valve 44 and controls the blower control circuit 51.
Controls the amount of combustion air supplied by the blower 52 based on the amount of heat generated by the proportional valve control circuit 43 to control the combustion state of the burner. In addition, the proportional valve control circuit 4 is controlled so as to obtain an optimum air-fuel ratio according to the actually measured output value of the combustion sensor 62.
3 or the blower control circuit 51.

FIG. 4 is an explanatory diagram showing a relationship between a current i as a control amount of the proportional control valve 44 and a rotation speed r as a control amount of the blower 52 in the proportional valve control circuit 43 and the blower control circuit 51. The solid control line in the drawing is a combination corresponding to the target control amount which is the setting state of the heat generation amount setting means, and the air-fuel ratio is theoretically the best. Therefore, by changing to the set temperature A, the control circuits 43 and 51 set the target current amount iA of the proportional control valve 44 and the point A of the target rotation speed rA of the blower 52. For that theoretical combination,
If it is determined that the combustion state of the burner is not the best than the combustion sensor due to clogging of the heat exchanger, output error of the drive motor, or the like, the rotation speed r of the blower 52 is adjusted until a predetermined combustion state is obtained. In this example, the air supply of the blower
At the point A 'increased from rA to rA', the output of the predetermined combustion sensor is obtained, and the air-fuel ratio control ends. Further, when the user continuously changes to the set temperature B, the combustion state at the point A 'is calculated by the calorific value setting circuit 81 to calculate the target control amount B point, and the proportional valve control or the blower control is performed. (Arrow R1) Then, the air-fuel ratio control along the arrow R2 is performed up to the control amount B 'at which the actual optimum air-fuel ratio is obtained by the combustion sensor 62.

[0004]

However, when performing the air-fuel ratio control for correcting the difference between the new target control amount B point and the actual control amount B 'point, the thermocouple used for the combustion sensor is different from the flame temperature. The combustion control of the burner deviates from the good combustion range while the measured output value of the flame temperature detected by the combustion sensor has an amplitude with respect to the target output value corresponding to the target control amount as shown in FIG. There is a disadvantage that. In particular, when the temperature change width is large, or when the temperature of the combustor itself is large, the temperature change is remarkable. Therefore, the present invention calculates the target control amount directly at the point B ′ based on the correction amount (A′−A) used in the air-fuel ratio control from the point A to the point A ′ of the immediately preceding temperature change, thereby setting the set temperature. It is an object of the present invention to always perform accurate air-fuel ratio control even during the change of the air-fuel ratio.

[0005]

In order to solve the above-mentioned problems, a combustor according to the present invention comprises a burner, a proportional control valve for adjusting a fuel supply amount to the burner, and a combustion air supplied to the burner. Blower, a combustion sensor for detecting a combustion state of the burner, a temperature sensor for detecting a tapping temperature, and a temperature setting device for arbitrarily setting a desired tapping temperature,
Control amount calculating means for calculating a target control amount for controlling the proportional control valve and the blower based on the hot and cold water temperature and the set temperature; and a combustion sensor for calculating a target value output from a combustion sensor corresponding to the target control amount. Target value calculation means, correction amount calculation means for calculating a correction amount for correcting the target control amount based on a target value and an actual output value of the combustion sensor, and a total of the target control amount and the correction amount Drive control means for driving and controlling the proportional control valve and the blower, when the tapping temperature deviates from a state substantially equal to the set temperature, regardless of the calculated correction amount, the correction amount used until immediately before Alternatively, a temperature change control means that employs a value based on the correction amount is provided.

[0006]

In the combustor of the present invention having the above-described structure, even if the difference in temperature change due to the set temperature change command is large or the temperature of the combustor having a large calorific value of the combustor itself is changed, the previously set temperature is not changed. Since the combustion state of the burner is set based on the correction amount calculated in the change command, the change of the set temperature can be completed without the air-fuel ratio deviating from the good combustion range.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a gas water heater embodying a combustor according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of a gas water heater. As shown in FIG. 1, this gas water heater 1
Is composed of a combustion unit 3 provided with a heat exchange unit 2, a gas supply unit 4 to the burner, a combustion air supply unit 5, and an electronic control circuit 6 for controlling them. A water supply flow rate sensor 22 is attached to the inlet-side water passage of the heat exchange unit 2, and a temperature sensor 23 for detecting tap water temperature is attached to the outlet-side water passage. The gas supply unit 4 includes a burner 4 attached below the heat exchange unit 2.
A solenoid valve 42 for supplying gas to the first and a proportional valve control circuit 43
And a proportional control valve 44 having The combustion air supply unit 5 supplies combustion air by a blower 52 driven by a motor M having a blower control circuit 51. The electronic control circuit 6 is connected to a tapping water temperature setting device 61 as a temperature setting device, and detects the oxygen supply state of the flame above the gas supply unit 4, the air supply unit 5, the flow sensor 22, the temperature sensor 23 and the burner 41. For example, drive control of a combustion sensor 62 (a thermocouple that detects a flame temperature is used in this embodiment) is performed.

Next, a control method of the proportional control valve and the blower will be described with reference to FIG. 2 which is a block diagram. The control amount calculating means 71 controls the proportional control valve 44 and the blower based on an output signal of the tapping temperature detected by the temperature sensor 23 and a reference signal arbitrarily set to a desired tapping temperature by the tapping temperature setting device 61. A target control amount for controlling 52 is calculated. The combustion sensor target value calculation means 72 calculates a target value output from the combustion sensor 62 corresponding to the target control amount. The correction amount calculating means 73 calculates the target control amount calculated by the control amount calculating means 71 based on the actual measured output value of the combustion sensor 62 and the target output value calculated by the combustion sensor target value calculating means 72. Is calculated, and the correction amount is stored. When the tapping temperature from the temperature sensor 23 is substantially equal to the preset temperature of the tapping temperature setting device 61, the temperature change control means 75 adopts the calculated correction amount or sets the tapping temperature to the preset value. When the temperature deviates from a state substantially equal to the temperature, regardless of the correction amount calculated above, the correction amount stored and used up to immediately before or a value converted by the characteristic of the control amount based on the correction amount as a new correction amount. adopt. Then, the correction amount is stored, and the total control amount is added to the target control amount and the correction amount. The proportional valve control circuit 43 which is one of the drive control means 74 controls the fuel supply amount to the proportional control valve 44 in accordance with the setting state of the temperature change control means 75 based on the total control amount. The blower control circuit 51 controls the supply amount of the combustion air to the blower 52.

The operation of the gas water heater 1 will be described with reference to the flowchart of FIG. First, in the case of normal combustion in which the set temperature A is not changed during the tapping and the set temperature A and the tapping temperature are substantially the same, Steps 1 and 2 are YES, and the combustion sensor 62 performs the combustion. The state is detected and the necessity of air-fuel ratio control is determined (step 3). In step 3, when the measured output value of the combustion sensor 62 is different from the target output value, the air-fuel ratio control is appropriately performed,
A correction amount for correcting the current target control amount in the correction amount calculating means 73 based on the actually measured output value of the combustion sensor 62 and the target output value calculated by the combustion sensor target value calculating means 72 is calculated in step 4. In step 5, the offset value is updated to store the correction amount. Then, in step 6, the blower control circuit 5
1 is subjected to air-fuel ratio control. The target of the air-fuel ratio control is the blower 52 in the present embodiment.
4 and / or the blower 52.

Next, immediately after the first temperature change setting from A to B, the new set temperature B and the tapping temperature A are different (step 1). Is set (step 7), the total control amount is calculated by adding the offset value to the temperature change control means 75 (step 8), and the proportional control valve 44 and the blower 52 are calculated.
Is controlled (step 9), and the process returns to step 1. And
When the set temperature B is almost the same as the tapping temperature, the process moves from step 1 to step 2 and waits for a response delay of the combustion sensor 62 for a certain period of time (step 2). Then, in a state where the reaction of the combustion sensor 62 for detecting the combustion state of the flame is good, the process proceeds to step 3, where the air-fuel ratio control described above is appropriately performed, and the normal combustion state is maintained.

Further, when a command to change to the second set temperature C is continued during the change to the set temperature B, the control is controlled to the new second set temperature C and the set temperature B first. Since the temperature is different from the tapping temperature that is being adjusted (step 1), the control amount calculation means 71 sets a target control amount corresponding to the second set temperature C (step 7). To calculate the total control amount (step 8), control the proportional control valve 44 and the blower 52 (step 9), and return to step 1. And 2
When the second set temperature C and the tapping temperature become substantially the same, the process proceeds from step 1 to step 2 to wait for a response delay of the combustion sensor 62 (step 2). Then, in a state where the reaction of the combustion sensor 62 for detecting the combustion state of the flame during the operation of the combustor has become good again, the process proceeds to step 3, and the normal combustion state is maintained.

The flow chart of FIG. 3 described above will be described with reference to FIG. 4 showing the relationship between the current i, which is the control amount of the proportional control valve 44, and the rotational speed r, which is the control amount of the blower 52, set in the drive control means 74. I do. If the change is not made from the set temperature A, the target current amount iA of the proportional control valve 44 corresponding to the target control amount calculated by the control amount calculation means 71.
The point A of the target rotation speed rA of the blower 52 is set.
When the set temperature and the tapping temperature are substantially the same, the process moves from step 1 to step 2 in the flowchart of FIG.
After waiting for the response delay of step 2 (step 2), the process proceeds to step 3 in a state where the reaction of the combustion sensor 62 for detecting the combustion state of the flame during the operation of the combustor is good, and based on the output of the combustion sensor 62. A point A ′ for correcting the air supply amount of the blower 52 from rA to rA ′ by air-fuel ratio control is set, the correction amount (A′−A) is updated as an offset value, and the normal combustion state is maintained. The described air-fuel ratio control is performed.

When the set temperature B is changed by the user, a point B corresponding to the newly calculated target control amount is set, and the temperature change control means 75 adds the correction value to the offset value. Then, a point B 'which is a total control amount is set. At this time, the correction amount is not based on the correction amount calculated by the correction amount calculating means 73 at the point B ′, but on the basis of the correction amount (A′−A) updated to the offset value. In particular, in this embodiment, the correction amount αi, which is a value calculated by approximation with a coefficient αi that varies according to the current i that is the control amount of the proportional control valve 44, instead of the rotation speed r that is the control amount of the blower 52, (A'-A) is adopted. Thus, in the prior art, the point B is calculated from the point A 'by the arrow R1, and when the air-fuel ratio control is performed by the combustion sensor 62 to the point B' by the arrow R2, the air-fuel ratio is good due to the response delay of the combustion sensor 62. In contrast to the case where the air-fuel ratio deviates from the range, in the present application, the point B 'is directly calculated from the point A by the arrow R3, and the drive control is performed by the drive control means, so that the air-fuel ratio is always controlled within the good combustion range. If the routine proceeds to step 3 in FIG. 3 and the normal combustion state is not maintained, the above-described air-fuel ratio control is performed.

If the user changes the temperature to the set temperature C while changing the temperature from the set temperature A to the temperature B, a point C corresponding to the newly calculated target control amount is set. The control means 75 adds the offset value, which is the correction amount, to set a total control amount C 'point. At this time, the correction amount αi (A′-A), which is a value approximated and calculated by the coefficient αi based on (A′−A) stored at the point A, is adopted as the correction amount. As a result, C ′ is directly transmitted from the point A by the arrow R4.
Since the points are calculated and drive control is performed by the drive control means,
Combustion control is always performed in the air-fuel ratio within the good combustion range.

In the embodiment, the feedback control for calculating the heat quantity from the temperature difference between the set temperature and the tapping temperature is performed. However, the temperature sensor 23 shown in FIG. According to 22, the feedforward control of multiplying the amount of heat by the temperature difference between the set temperature and the incoming water temperature by the amount of incoming water can also be performed. Further, as the combustion sensor 62 for detecting the combustion state, an oxygen sensor, a frame rod, or the like may be used in addition to the thermocouple.

[0016]

As described in detail above, according to the present invention, when the tapping temperature deviates from a state substantially equal to the temperature set by the temperature setting device, the temperature is not affected by the correction amount calculated by the correction amount calculating means. Instead, the correction amount used up to immediately before or a value based on the correction amount is adopted, so when the temperature change difference due to the set temperature change command is large or when the temperature change in the combustor with a large heat generation amount of the combustor itself. Even so, the combustion state of the burner is set based on the correction amount calculated in the previously set temperature change command, so that the air-fuel ratio control by the combustion sensor can be omitted and the air-fuel ratio control is required. Even in this case, the change in the set temperature can be ended without the air-fuel ratio deviating from the good combustion range because the change amount for the air-fuel ratio control is small.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a combustor according to the present invention.

FIG. 2 is a block diagram of a combustor according to the present invention.

FIG. 3 is a flowchart showing the operation of the combustor according to the present invention.

FIG. 4 is a graph showing a relationship between a current i and a rotational speed r, which are control amounts in a control amount calculating means.

FIG. 5 is a block diagram of a conventional combustor.

FIG. 6 is a diagram illustrating the reactivity of a thermocouple to a flame.

[Explanation of symbols]

1. Gas water heater, 2. Heat exchange unit, 3. Combustion unit, 4.
..Gas supply unit, 5 air supply unit, 6 electronic control circuit, 22 flow rate sensor 23 temperature sensor 41
..Burner, 42 .. solenoid valve, 43 .. proportional valve control circuit, 44 .. proportional control valve, 51 .. blower control circuit, 5
2. Blower, 61 hot water temperature setting device, 62 combustion sensor, 71 control amount calculation means, 72 combustion sensor target value calculation means, 73 correction amount calculation means, 74
Drive control means, 75... Temperature change control means.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F23N 5/02 350 F23N 1/02 101 F23N 5/00 F24H 1/10 302

Claims (1)

(57) [Claims] A burner; a proportional control valve for adjusting a fuel supply amount to the burner; a blower for supplying combustion air to the burner; a combustion sensor for detecting a combustion state of the burner; A temperature sensor for detecting, a temperature setting device for arbitrarily setting a desired tapping temperature, and a control amount calculating means for calculating a target control amount for controlling the proportional control valve and the blower based on the tapping temperature and the set temperature. A combustion sensor target value calculation means for calculating a target value output from the combustion sensor in accordance with the target control amount, based on a target value and an actual output value of the combustion sensor,
Correction amount calculating means for calculating a correction amount for correcting the target control amount; drive control means for driving and controlling the proportional control valve and the blower based on a sum of the target control amount and the correction amount; Temperature change control means for adopting the correction amount used immediately before or a value based on the correction amount regardless of the correction amount calculated when the state deviates from a state substantially equal to the set temperature. Combustor.