JPH03199815A - Combustion device - Google Patents

Abstract

PURPOSE:To correct an amount of supplied air and to enable a stable combustion to be kept by a method wherein an actual combustion state is supervised by an oxygen sensor mounted in a combustion exhaust gas passage and the combustion state is applied as an element for controlling the amount of combustion air for a control device. CONSTITUTION:Fuel passed through a solenoid valve 6 and a proportional valve 6 is injected from a nozzle 6 into a burner 8. The fuel is mixed with combustion air fed by a combustion fan 10 and then ignited. Combustion exhaust gas is discharged out of a discharging port 4a and a concentration of O2 in the exhaust gas is sensed by an O2 sensor. In turn, the degree of opening of the proportional valve 6 is determined in response to a difference between a set temperature and a room temperature and its corresponding fuel is fed to a nozzle 7. For exanple, in the event that a concentration of O2 becomes 21% which is substantially the same as that of surrounding air and there is a certain difference between it and the set value, a combustion fan motor 10 may ignore a sensing value from the O2 sensor for a period of (t) time and then the fan motor is rotated at the set number of revolution. When the degree of opening of the proportional valve 6 is changed over, it may ignore the sensed value for a period of (t) time. After elapsing the time (t), the rotation of the combustion fan 10 is controlled in such a way as it becomes the concentration of the O2 sensor 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a combustion device applied to, for example, a hot air heater.

(Prior Art) This type of combustion apparatus generally includes a fuel supply system, a forced combustion air supply system, a combustion section, and a combustion exhaust gas path. In recent years, many devices have been designed to proportionally control the amount of fuel supplied depending on the load, such as room temperature, to stabilize the load. However, in the case of a combustion device that controls the fuel supply amount by proportional control, in order to maintain good combustion conditions, it is necessary to ensure the supply amount of combustion air in response to changes in the fuel supply amount. If the amount of air supplied is insufficient, the combustion condition will deteriorate, and carbon monoxide (
CO) amount may increase or misfire may occur. For this reason, measures have been taken such as changing the rotation speed of a combustion air supply fan, which is a forced combustion air supply system, in accordance with the proportional control of the fuel supply amount.

(Problem to be Solved by the Invention) However, even in a combustion device that takes such measures, the correlation between the control amount (for example, current value) of the proportional valve in the fuel supply system and the amount of fuel has not been measured in advance. Since the control amount and the fan rotation speed are controlled in advance, the relationship between the control amount and the fuel supply amount may deviate, or the exhaust port facing the outside air may be exposed to strong winds and excess wind pressure may cause the air to flow out. If the amount decreases, combustion conditions may deteriorate.

The present invention has been made in view of the above circumstances, and aims to provide a combustion device that can maintain a stable combustion state in response to actual circumstances even when the amount of fuel supply or the amount of combustion air changes. purpose.

[Structure of the invention]

(Means for Solving the Problems) The present invention includes a fuel supply system, a forced combustion air supply system, a combustion section, and a combustion exhaust gas path, and proportionally controls the fuel supply amount according to the load. In a combustion apparatus having a control device that controls the supply amount of combustion air in response to proportional control of the combustion air, an oxygen sensor is installed in the combustion exhaust gas path, and the amount of oxygen in the exhaust gas detected by the oxygen sensor is controlled by the control device. is input as a combustion air amount control element.

(Function) According to the present invention, the actual combustion state is monitored by the oxygen sensor installed in the combustion exhaust gas path and used as a combustion air amount control element of the control device. Even if the amount changes,
By increasing or decreasing the rotation speed of the combustion fan motor, etc., the amount of supplied air can be corrected, and stable combustion can be maintained.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the overall configuration of a combustion device applied to a hot air heater. The combustion apparatus of this embodiment includes a fuel supply system 1, a forced combustion air supply system 2, a combustion section 3, and a combustion exhaust gas path 4. The fuel supply system 1 has a solenoid valve 5 and a proportional valve 6, and the fuel is supplied to the fuel nozzle 7 through the solenoid valve 5 and the proportional valve 6, and when injected into the burner 8, entrains combustion air. The mixture is mixed at burner 8.
The fuel is ejected from the combustion tube 8a.

On the other hand, the combustion air forced supply system 2 has a combustion air supply fan 10 that is rotationally driven by a fan motor 9, and the combustion air supplied by this fan 10 is mixed with fuel in the burner 8. and then subjected to combustion. In addition, in order to monitor the combustion state, a flame detector 11 is installed in the combustion tube 8a.
The fan motor 9 is also provided with rotation speed detection means,
For example, a Hall element 9a is provided.

A bimetal thermostat 12 is installed near the combustion tube 8a.
is provided, and when the combustion cylinder is heated, the convection fan motor 1
3a is rotationally driven, and the convection fan 13 blows air. An indoor temperature detector 14 is provided upstream of the convection fan 13.
The detected value is input to the control device 1.5, and the opening of the proportional valve 6 or the start/stop of combustion is controlled based on the difference from the room temperature.

Figure 2 shows the set temperature (TS) of the indoor temperature detector and the room temperature (R
It shows the opening degree of the proportional valve depending on the difference between T) and T). When the set temperature≦room temperature, the proportional valve 6 is closed, and when the room temperature is low, the proportional valve 6 is opened according to the temperature difference.

In addition, in FIG. 2, the 02 density is represented by E1 to E5.

The combustion tube 8a has an exhaust port 4a that constitutes the combustion exhaust gas path 4.
is formed, and combustion gas is guided from the combustion tube 8a to the exhaust port 4a. An oxygen sensor (hereinafter referred to as 02 sensor) 16 is installed near the exhaust port 4a to detect the oxygen concentration in the combustion exhaust gas. This 0
The amount of oxygen in the exhaust gas detected by the two sensors is input to the control device 15 as a combustion air amount control element. That is, the optimal combustion state at each valve opening of the proportional valve 6 is measured in advance, and the 02 sensor concentration is stored in the control device 15.

Next, the operation will be explained with reference to FIG. FIG. 3 shows the combustion flow, with the X-axis showing the passage of time, and the Y-axis showing the proportional valve opening, the combustion fan rotation speed, and the 02 concentration.

The fuel that has passed through the electromagnetic valve 5 and the proportional valve 6 is ejected from a nozzle 7 to a burner 8, mixed with combustion air sent by a combustion fan 10, and combusted. Combustion exhaust gas is discharged from exhaust port 4a
The 02 concentration in this exhaust gas is detected by the 02 sensor.

On the other hand, the opening degree of the proportional valve 6 is determined by the difference between the set temperature and the room temperature, and fuel corresponding to the opening degree is sent to the nozzle 7. For example, depending on the opening degree of the proportional valve 6, the 02 concentration will be approximately 2
If the difference is 1% from the set value, the combustion fan motor 10 ignores the detected value from the 02 sensor for 1 hour (for example, 0 to 15 seconds) as shown in FIG. Rotates at the set rotation speed.

Further, when the opening degree of the proportional valve 6 is changed, the detected value is ignored for one hour as described above. After the time has elapsed, the rotation of the combustion fan 10 is controlled to maintain the concentration of the 02 sensor 16, and even if the amount of fuel and combustion air changes, the 02 concentration in the exhaust gas is maintained at an optimal level. It starts to sag.

Therefore, according to this embodiment, the combustion fan 10 is controlled so that the O2 concentration in the exhaust gas is always in the optimum state, so that a stable combustion state is maintained. Note that when starting combustion or when the valve opening changes, the 02
Since the concentration value detected by the sensor 16 is ignored, misfires will not occur even in transient conditions.

Although the above embodiments have been described using a heater as an example, the present invention can be applied to various combustion devices that perform proportional control.

〔Effect of the invention〕

As described above, according to the combustion device according to the present invention, the actual combustion state is monitored by the oxygen sensor installed in the combustion exhaust gas path, and is used as a combustion air amount control element of the control device. Even if the amount of combustion air changes due to reasons such as the following, the amount of air supplied can be corrected by increasing or decreasing the rotation speed of the combustion fan motor, etc., and stable combustion can be maintained.

[Brief explanation of drawings]

Figure 1 is a block diagram showing one embodiment of the present invention, Figure 2 is a diagram showing the opening degree of the proportional valve and the optimum 02 concentration depending on the difference between the set temperature and room temperature, and Figure 3 is a diagram showing the combustion action. be. J... Fuel supply system, 2... Forced air supply system, 3...
- Combustion section, 4... Combustion exhaust gas path, 15... Control device, 1-6... Oxygen sensor.

Claims (1)

[Claims] Equipped with a fuel supply system, a forced combustion air supply system, a combustion section, and a combustion exhaust gas path, the amount of fuel supplied is proportionally controlled according to the load, and the amount of combustion air supplied is controlled in accordance with the proportional control of the amount of fuel supplied. In the combustion apparatus having a control device for controlling the combustion air, an oxygen sensor is installed in the combustion exhaust gas path, and the amount of oxygen in the exhaust gas detected by the oxygen sensor is input to the control device as a combustion air amount control element. Combustion equipment.