JP2774027B2 - Combustion control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel adjusting means for adjusting a fuel supply amount to a burner, an air amount adjusting means for adjusting a combustion air supply amount to the burner, the fuel adjusting means and the air. Control means for controlling the operation of the amount adjusting means, wherein the control mode of the control means includes a steady mode in which the air-fuel ratio is controlled to a steady target value, and an ignition set value in which the air-fuel ratio is larger than the steady target value. An ignition mode for igniting the burner, wherein the control means executes the ignition mode and then shifts to the steady mode when starting combustion of the burner. It relates to a control device.

[0002]

2. Description of the Related Art When igniting a burner, if the air-fuel ratio is too high, the burner will not ignite. On the other hand, if the air-fuel ratio is too low, an abnormal combustion state occurs, which causes problems such as generation of abnormal noise and an increase in the amount of CO generated. That is, in FIG. 3, if the air-fuel ratio is higher than the fire limit line L1, the fire does not start to the burner, and if the air-fuel ratio is lower than the ignition abnormal sound limit line L2, an abnormal combustion state may occur. Therefore, the region where the burner can be ignited normally is limited between the fire limit line L1 and the abnormal ignition sound limit line L2. The ignition set value S1 is set in the vicinity of the center in the above-mentioned area. On the other hand,
The air-fuel ratio (steady target value) during steady combustion is set on the control line Lc. Therefore, it is necessary to shift the air-fuel ratio to the control line Lc after setting the air-fuel ratio to the ignition set value S1 and igniting the burner. Conventionally, the air-fuel ratio has been shifted to the control line Lc immediately after igniting the burner as shown by a dotted arrow.

[0003]

If the exhaust passage of the burner is blocked or if there is a variation in characteristics among the individual burners, the air-fuel ratio at the time of actual ignition will deviate from the set value for ignition. . Here, if the air-fuel ratio at the time of actual ignition deviates from the above-mentioned region beyond the ignition abnormal sound limit line, an abnormal combustion state occurs. Here, if the air-fuel ratio is shifted to the control line immediately after the burner is ignited as in the above-described prior art, there is a possibility that the abnormal combustion state generated at the time of ignition will continue without being eliminated even after shifting to the steady state combustion. was there. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional drawbacks, and to eliminate the abnormal combustion state immediately even if an abnormal combustion state occurs at the time of ignition, and to shift to a steady combustion state in a state where abnormal noise and excessive CO are eliminated. The point is to get a control device.

[0004]

In order to achieve this object, a characteristic configuration of the combustion control device according to the present invention is that an intermediate control for controlling the air-fuel ratio to an intermediate set value larger than the ignition set value in the control mode. A mode is provided, and the control means is configured to, when starting the combustion of the burner, shift to the steady mode via the intermediate mode after the execution of the ignition mode.

[0005]

When the abnormal combustion state occurs, the abnormal combustion state can be eliminated by increasing the air-fuel ratio. That is, in FIG. 3, the air-fuel ratio is changed to the abnormal sound stop limit line L
If it is higher than 3, the abnormal combustion state can be eliminated. Therefore, as shown by the actual arrow, after the burner is ignited, the air-fuel ratio is once increased to be higher than the abnormal sound stop limit line L3, and then the air-fuel ratio is shifted to the control line Lc. , The abnormal combustion state can be eliminated. L4 in FIG. 3 is a lift limit line indicating a limit at which the flame causes a lift. Intermediate set value S2
Are the abnormal sound stop limit line L3 and the lift limit line L4
Is set between

[0006]

The control in the ignition mode and the steady mode is the same as in the conventional case. Therefore, the performance at the time of ignition or steady combustion is not adversely affected. That is, the abnormal combustion state can be eliminated without adversely affecting the ignition performance and the combustion performance.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a water heater will be described below with reference to the drawings. As shown in FIG. 1, a heat exchanger 1 for heating water, a burner 2 for heating the heat exchanger 1, and a fan as air amount adjusting means for adjusting the amount of combustion air to the burner 2 3 is provided. The fan 3 is provided with a rotation speed sensor. In the figure, W1 is a water supply passage for the heat exchanger 1, W2 is a hot water supply passage, and W3 is a bypass passage. The fuel gas supply path G1 for the burner 2 is provided with two on-off valves 4 and 5 for intermittently supplying fuel gas, and an electromagnetic gas amount adjusting valve 6 as fuel adjusting means for adjusting the fuel supply amount. I have. A water flow sensor S1 for detecting the amount of water supplied to the heat exchanger 1 and an incoming water temperature sensor S2 for detecting the temperature of incoming water to the heat exchanger 1 are provided in the water supply passage W1, and the heat exchanger 1 is provided in the hot water supply passage W2. And a bypass solenoid valve is interposed in the bypass passage W3. In the drawing, reference numeral 7 denotes an igniter, 8 denotes a frame rod for detecting whether or not the burner 2 has ignited, and 9 denotes a closing body for reducing the outlet area of the fan 3. Here, the decrease in the amount of combustion air due to the provision of the closing body 9 is corrected by increasing the rotation speed of the fan 3. This is because the pressure at the outlet of the fan 3 is increased and the burner 2
This is a measure to reduce the effect of pressure fluctuations at the time.

Further, a main remote controller R1 for instructing the controller H to issue control information and a bath remote controller R2 are provided. The main remote controller R1 is provided with an operation switch 21 for instructing start / stop of operation, a hot water supply temperature display 22, a hot water supply temperature setting device 23, and the like. Bath remote control R2
Is provided with an operation switch 31, a hot water supply temperature indicator 32, a reheating switch 33, a hot water switch 34, and the like.

The controller H is connected to a water amount sensor S1, an incoming water temperature sensor S2, a hot water temperature sensor S3, a frame rod 8, a main remote controller R1, and a bath remote controller R2. Then, the controller H controls the operation of the gas amount adjusting valve 6 and the fan 3 based on information set and stored in advance and various kinds of input information. That is, the control unit 100 is configured using the controller H.

The control modes of the gas amount adjusting valve 6 and the fan 3 include an ignition mode, a steady mode, and an intermediate mode. Hereinafter, each mode will be described with reference to FIG. The horizontal axis in FIG. 3 is the gas amount Gp, and the vertical axis is the fan rotation speed Ns.
Is shown. First, in the steady mode, the control line L
On c, the gas amount Gp and the fan rotation speed Ns are controlled. The control line Lc is set so that the air-fuel ratio becomes a steady target value. That is, when the gas amount Gp is determined from the target combustion amount, the fan rotation speed Ns corresponding to the gas amount Gp can be determined from the control line Lc. In the ignition mode, the air-fuel ratio is set to an ignition set value S1 larger than the steady target value. The ignition set value S1 is set between the fire limit line L1 and the abnormal ignition sound limit line L2. The gas amount Gp at the ignition set value S1 is G
1. The fan rotation speed Ns is N1. In the ignition mode, the igniter 7 is operated to ignite the burner 2.
It should be noted that the fire limit line L1 indicates a limit at which the fire does not catch the burner if the air-fuel ratio is higher than this line. The ignition abnormal sound limit line L2 indicates a limit at which an abnormal combustion state occurs when the air-fuel ratio is lower than this line. In the intermediate mode, the air-fuel ratio is set to an intermediate set value S2 larger than the ignition set value S1.
The intermediate set value S2 is set between the abnormal sound stop limit line L3 and the lift limit line L4. The gas amount Gp at the intermediate set value S2 is G2 (G1−ΔG), and the fan speed Ns is N1. The abnormal sound stop limit line L3 is
Even when an abnormal combustion state is occurring, a limit at which the abnormal combustion state can be eliminated by setting the air-fuel ratio higher than this line is shown. The lift limit line L4 indicates a limit at which the flame lifts when the air-fuel ratio is higher than this line.

Next, the operation of the controller H will be described with reference to the flowchart shown in FIG. First, the necessity of hot water supply is determined, and in the case where hot water supply is not necessary, it is determined whether hot water is currently being supplied. If hot water is not being supplied until now, the process returns. If the hot water is being supplied until now, the process returns after executing the fire extinguishing process. If it is determined that hot water supply is required, it is determined whether or not ignition is being performed. If ignition is not being performed, the ignition mode is executed, and the intermediate mode is further executed for the set time.
Then, the mode shifts to the steady mode. When the ignition is being performed, the mode directly shifts to the steady mode. The above operation is repeated every predetermined time.

[Alternative Embodiment] In the above-described embodiment, the embodiment in which the present invention is applied to a water heater is shown. However, the present invention can also be applied to a fan heater or the like. In boiler combustion, for example, the fan may be rotated at a constant speed to adjust the amount of air according to the degree of opening of the damper, and the specific configuration of each unit such as the air amount adjusting means may be variously changed.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of the drawings]

FIG. 1 is a block diagram of the overall configuration.

FIG. 2 is a flowchart of a control operation;

FIG. 3 is an explanatory diagram showing a relationship between a gas amount and a fan rotation speed.

[Explanation of symbols]

 2 burner 3 air amount adjusting means 6 fuel adjusting means 100 control means S1 ignition set value S2 intermediate set value

Continuation of front page (56) References JP-A-3-137414 (JP, A) JP-A-1-134113 (JP, A) JP-A-58-160733 (JP, A) JP-A-63-169420 (JP) , A) (58) Field surveyed (Int.Cl. ⁶ , DB name) F23N 1/02

Claims (1)

(57) [Claims] A fuel adjusting means for adjusting an amount of fuel supplied to the burner; an air amount adjusting means for adjusting an amount of combustion air supplied to the burner; A fuel adjusting means (6) and a control means (100) for controlling the operation of the air amount adjusting means (3) are provided, and the control mode of the control means (100) controls the air-fuel ratio to a steady target value. A steady mode and an ignition mode in which an air-fuel ratio is set to an ignition set value (S1) larger than the steady target value and the burner (2) is ignited;
Is a combustion control device configured to execute the ignition mode and then shift to the steady mode when starting combustion of the burner (2). The ignition set value (S1)
An intermediate mode for controlling to a larger intermediate set value (S2) is provided, and when the control means (100) starts the combustion of the burner (2), the intermediate mode is set after the execution of the ignition mode. A combustion control device configured to shift to the steady mode via the control unit.