JPH0231289B2 - KAENDENRYUKENSHUTSUSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a safety device for combustion equipment having a plurality of burners, and has a simple configuration that detects abnormal combustion conditions such as oxygen deficiency at one judgment level over the entire variable combustion amount range. The object of the present invention is to provide a flame current detection device using a flame rod.

In the conventional flame current detection device using flame rods, multiple burners were electrically at the same potential as the main body of the equipment including the heat exchanger, so even if the burners attached with flame rods were set to a fixed combustion rate, they could be used on the variable combustion rate side. The effects of this (flame interference, etc.) appeared as detected flame current. Furthermore, due to the actual equipment configuration, it is difficult in terms of cost to maintain a distance that completely eliminates flame interference due to changes in the combustion amount of other burners. Therefore, in response to differences in fuel types and changes in combustion amount, it is necessary to take the trouble to set the flame current level for determining abnormal combustion in multiple stages, or to vary it linearly when the combustion amount changes linearly, which is complicated due to the circuit configuration. Moreover, the cost is also likely to increase. In addition, even if only the flame rod-mounted burner is insulated from the main body of the equipment or other burners, the influence of changes in combustion amount due to other burners will be reduced. The problem of design margin) remains.

The present invention provides a combustion equipment in which a plurality of burners are used in the equipment configuration, in which each burner is electrically insulated from the equipment body and between each burner using an insulator or the like, and a flame rod is used as a fixed combustion rate burner. Moreover, by connecting the fixed combustion rate burner and another variable combustion rate burner through a certain resistance, problems such as the complexity of the configuration and increased cost due to level setting switching in the conventional example, and the problem of level setting. This solves the problem of the possibility of

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 shows the configuration of the present invention for a gas combustion device using two burners. The flame rod 1 is attached to a fixed combustion rate burner 2 (hereinafter referred to as burner 2), and a variable combustion rate burner 3 (hereinafter referred to as burner 3) and burner 2 are electrically insulated from the main body of the device. be. Further, the burner 3 is connected to the burner 2 via a resistor 4. Reference numeral 5 denotes a control circuit unit that takes in a signal from the above-mentioned flame current detection device and controls the gas supply solenoid valve 6. 7 (G ₁ ) is a governor for varying the combustion amount of the burner 3;
8 (G ₂ ) is a fixed governor for burner 2, which prevents the influence of source pressure and G ₁ fluctuations from being transmitted to burner 2 as gas pressure fluctuations. The flame rod signal is influenced by the burner 3 via the resistor 4, but as will be described later, it is possible to set one oxygen deficiency cutoff level in the entire variable combustion amount range.

FIG. 2 shows a specific example of the flame current detection device and the control circuit section. The household AC power supply 9 is a transformer 10
is transmitted to the secondary side by The power supply on the comparison potential side is a rectifier diode 11 and a smoothing capacitor 1.
It is made of 2. The signal from the oscillation circuit 13 is transmitted to the switching transistor 16 via the resistors 14 and 15, and then to the switching transistor 16 via the resistor 17.
The source potential of the JFET transistor 21 determined by the voltage divisions 19 and 20 is changed. 2
2 is a resistor connected to the drain side of the transistor 21, and serves as an inverting input potential of the comparator 23. Further, the connection point between the resistors 18 and 19 is a non-inverting input, and the comparator output is limited by the operation of the transistor 21. The gate potential of the transistor 21 is set such that the signal from the flame current detection device of the present invention is connected to the resistors 24 and 2.
5 and a capacitor 26, and is applied through a gate current limiting resistor 27. 28 receives the output of the comparator 23 and connects the pulse transformer 3
This serves as the base resistance of the transistor 29 for transmitting the oscillation signal to the transistor 29. 31 is transformer 30
This is a diode for absorbing back electromotive force on the primary side. 3
2 is a diode for secondary side rectification, and 33 is a smoothing capacitor. By closing the ignition operation switch 34, the adsorption power of the gas supply solenoid valve 6 is applied to the power supply 9 through the resistor 35 and the diode 36.
It is given directly from 37 is a diode for not transmitting a large voltage to the capacitor 33 during adsorption.

FIG. 3 and subsequent figures compare the characteristics of the burners 2 and 3 connected through the resistor 4 with other burners, and explain solutions to problems in the conventional example.

The horizontal axis of FIG. 3 represents the oxygen (O ₂ ) concentration, and the vertical axis represents the detected flame current i _fl . The characteristics in the present invention are b, and a is when burners 2 and 3 are directly connected;
Alternatively, none of the burners are insulated from the body. c shows the flame current characteristics of only burner 2 when R ₄ is open. From this characteristic diagram, the slope of c with respect to the O ₂ concentration is the gentlest, and the slope of a has the largest amount of change. b is located between them. FIG. 3 shows the difference in characteristics due to the different burner connection methods when burning a certain amount.

Next, FIG. 4 shows the change characteristics of flame current in the flame current detection device of the present invention. In other words, the vertical axis is the flame current value, the horizontal axis is the oxygen concentration,
When the combustion amount on the variable combustion amount burner side reaches the maximum (Q ₁ ) and minimum (Q ₂ ), additional conditions include composition variations in the specified gas type and extreme characteristics including gas pressure fluctuations. represents.

When gas combustion appliances are used continuously in a closed room, the oxygen concentration in the air decreases, resulting in an oxygen-deficient condition, and if combustion continues in that environment, CO is produced or a large amount of CO ₂ is produced. Shifts to an abnormal combustion state that occurs. Therefore, it is necessary to detect the situation before it shifts to this abnormal combustion state to ensure the safety of using gas combustion appliances. 16% of this figure is the CO
This is the standard oxygen concentration at the time of generation or when a large amount of _CO2 is generated, and it is necessary to detect the condition and stop gas combustion before it drops below this value. In addition, 19.5% is the oxygen concentration that can be reached fairly easily (about 1 hour after the start of use) when using a gas combustion appliance for heating in a general room (6 tatami area); Normal combustion conditions must be maintained in the oxygen concentration range. In other words, in order to configure the abnormal combustion detection level at a single predetermined flame current value, it is necessary to control the oxygen concentration as explained above, regardless of the combustion amount (for example, from strong combustion to weak combustion). become. It continues combustion at an oxygen concentration of 19.5% or more, and stops combustion at an oxygen concentration of 16% or less.
Abnormal combustion state detection must be achieved between % and 16%. In the present invention, as shown in the figure, at the maximum combustion amount of _Q1 , the flame current can be larger than the minimum combustion amount of _Q2 , so the oxygen concentration region is 19.5%.
The flame current of 16% from _Q1 is also larger. Therefore,
Maximum combustion of flame current value at 16% oxygen concentration
The value i _fl2 at Q ₁ must be smaller than the value i _fl1 at the minimum combustion time Q ₂ of the flame current value at an oxygen concentration of 19.5%, and the fourth
From the figure, it can be seen that the flame current condition is satisfied. In addition, when setting the level using an actual device, the more positive and larger Δi _fl =i _fl1 −i _fl2 is, the easier the circuit design will be.

In addition, FIG. 5 shows a, b,
In the burner connection configuration shown in c, the flame current characteristics are shown when the combustion rate of the device is continuously changed from weak to strong using a variable combustion rate burner, and the solid line below each shaded area indicates the oxygen concentration 16 at each combustion rate. % flame current values, and the solid line above each region is a characteristic that connects the flame current values at an oxygen concentration of 19.5% at each combustion amount. In other words, as shown in Figure 4
i _fl1 is equivalent to the flame current at the intersection of the upper solid line and the weak combustion line in zone b in Figure 5,
i _fl2 shown in FIG. 4 is equivalent to the flame current at the intersection of the lower solid line and the strong combustion line in zone b in FIG. 5. As is clear from the figure, in connection configurations a and c, the gradient of change in flame current is large in the range from weak to strong combustion, and it is not possible to design the abnormal combustion state determination level based on a single predetermined flame current value. do not have. However, in the connection configuration b in which the flame interference of the present invention is appropriately applied, it is possible to set the abnormality determination level at a single predetermined flame current value within a design variation tolerance range. This is a characteristic that can be realized by appropriately selecting the resistance 4 between the burners of the present invention depending on the gas type and the variable combustion amount region depending on the appliance.

With the configuration of the present invention, abnormal combustion conditions such as oxygen deficiency that occur when a combustion appliance is used in a closed room can be determined by setting one flame current level over the entire combustion amount variable region. It is possible to do so. This eliminates the need to set the level for determining abnormal combustion in multiple stages or linearly depending on the amount of combustion, making it possible to provide a flame current detection device with a simple circuit configuration.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram of a combustion device incorporating a flame current detection device according to an embodiment of the present invention;
Fig. 2 is a specific control circuit diagram of the flame current detection device of the present invention, Fig. 3 is a diagram showing the relationship between oxygen concentration and flame current, and Fig. 4 is a diagram showing the oxygen concentration including differences in combustion amount and gas type. FIG. 5 is a diagram showing the relationship between combustion amount and flame current. 1...flame rod, 2...constant combustion rate burner to which flame rod is attached, 3...burner with variable combustion rate, 4...resistance connected between the burners.

Claims (1)

[Claims] 1. A combustion device having a plurality of burners electrically insulated from the main body of the device and from each other,
A flame current detection device characterized in that a constant combustion amount burner equipped with a flame rod and another variable combustion amount burner are connected via a resistor. 2. The flame current detection device according to claim 1, characterized in that the resistance between the burners is changed depending on the type of fuel.