JPS6291720A - Combustion detecting device - Google Patents

Abstract

PURPOSE:To make it possible to positively detect oxygen starvation regardless of strong or weak combustion by providing oxygen starvation discriminating means changing the oxygen starvation detection level in accordance with the quantity of combustion. CONSTITUTION:Analog input terminals AN1, AN2 and AN3 provided within a microcomputer 28 directly read in analog voltages, and connected to room temperature detection means 22, temperature setting means 34, and combustion state detection means 28. Within the microcomputer 28, an analog voltage from a room temperature detection means 33 is supplied through AN1, and an analog voltage from temperature setting means 34 through AN2. Both signals are compared with each other by combustion quantity determining means 35, and thus the quantity of combustion is determined. Combustion control means 36 causes combustion to be carried out based on the quantity of combustion and through combustion drive means 37. On the other hand, oxygen starvation discriminating means 39 compares an oxygen detecting level determined in the microcomputer 28 in accordance with the quantity of combustion with an analog voltage supplied to AN3 from combustion state detection means 38, and combustion control means 36 delivers a combustion extraordinary signal or a normal signal to combustion control means.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a combustion detection device for a combustor, and is particularly intended to improve oxygen deficiency detection characteristics.

Conventional technology plays an important role in indoor open type combustors such as oil 7 unheaters that use indoor air as combustion air, so if combustion continues for a long time in a closed room, it will become deficient in oxygen and cause abnormal combustion such as red flames. A situation occurs in which carbon monoxide is generated and poses a threat to human life. For this reason, it has recently become common practice for this type of combustor to be equipped with an oxygen deficiency detection device that issues an alarm or stops combustion when oxygen deficiency is detected.

For example, an oil fan heater is provided with an oil cylinder 3 and a burner unit 4 inside an external device and a base 2, as shown in FIG. Combustion gas A burned in burner unit 4
A fan 6 attached to a blower motor 5 blows out warm air C along with indoor air B from a front looper 7, which is provided for indoor heating. FIG. 5 is a schematic diagram of the burner. Kerosene is vaporized and mixed with air for optimal combustion. A mixed gas is ejected from the mesh 8 at the top of the burner and ignited by the ignition electrode 9 to form a combustion flame F.

A voltage is applied between the flame rod 10 placed in the flame F and the burner case 11, and the rectification phenomenon of the flame F is used to check the state of the flame F and detect an oxygen deficiency state. There is. 7 frame rods 10 and burner case 1
1, there is a circuit as shown in FIG. That is, AC power supply 12, resistors 13, 14, 15, capacitor 16,
The operational amplifier 19 compares the potentials at point a of the circuit consisting of burner case 11 and frame rod 10 and point b of the circuit consisting of DC type #16 and resistor 17.18. A current due to the rectification phenomenon of the flame between the rod 10 is charged in the capacitor 16, and the potential at point a changes.

The operation of the combustion detection device configured as described above will be described below. First, when the combustion condition is good, the charge in the capacitor 16 increases, and the potential VaO at point a becomes higher than the potential vb at point b, and the potential Vc at point 0, which is the output of the operational amplifier 19, is logic 1 (H )become. When oxygen deficiency begins to occur, the combustion condition deteriorates and Va (Vb) is reached.
The output Vc of the operational amplifier becomes logic 0 (L). The signal that detects the oxygen deficiency state in this manner is input to the overall control circuit 20 and controls each load 21.

Problems to be Solved by the Invention However, in the conventional configuration described above, in a normal combustion state where the ratio of air to combustion amount is constant, the rectification phenomenon of the flame rod is good during strong combustion, and the flame rod output Va is sufficient. However, during weak combustion, the flame F comes into close contact with the mesh (flame port) 8, and the influence of the flame on the flame rod is extremely small, so as shown in Figure 6, the output of Va is , the oxygen deficiency detection level v2 is lower than that in strong twist firing, and even though combustion is normal, a malfunction occurs in which it is considered abnormal combustion. (The oxygen deficiency detection level here refers to the potential at point a in Figure 8 when the oxygen concentration is 18% or less of the atmosphere.) In other words, as shown in Figure 7, the oxygen concentration is 1
There was a problem in that oxygen deficiency was detected at a level below 8% (approximately 20%). This can be solved to some extent by installing the frame rod 10 closer to the mesh (flame port) 8, but in this case, in strong twist firing,
7 The frame rod will come into contact with the inner flame (incomplete), making it impossible to obtain a normal flame rod output voltage. Further, a slight thermal deformation of the frame rod causes the inconvenience that the mesh (flame port) 8 and the frame rod 10 come into contact with each other.

The present invention is intended to solve the above-mentioned conventional problems, and aims to enable reliable detection of oxygen deficiency regardless of strong or weak combustion.

Means for Solving the Problems In order to achieve this object, the combustion detection device of the present invention is provided with oxygen deficiency determining means for changing the oxygen deficiency detection level in accordance with the amount of combustion.

Operation According to the present invention, even if the detection voltage of the flame rod decreases during weak combustion, the oxygen deficiency detection level also decreases by an amount commensurate with the decrease in the detection voltage of the flame rod due to the above-described configuration. Therefore, malfunctions such as activation of oxygen deficiency detection during normal combustion can be prevented, and detection accuracy and equipment safety can be improved.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a combustion detection device according to an embodiment of the present invention. In FIG. 1, ANl, AN2,
AN3 is an analog input terminal on the microcomputer 28, which can directly read an analog voltage, and is connected to room temperature detection means 33, temperature setting means 34, and combustion state detection means 38, respectively. On the other hand, in the microcomputer 28, the analog voltage from the room temperature detection means 33 is inputted from ANI, and the analog voltage from the temperature setting means 34 is inputted from AN2, and the two are compared by the combustion amount determining means 35 to determine the combustion amount. . The combustion control means 36 causes combustion to occur through the combustion drive means 37 based on the combustion amount.

On the other hand, the oxygen deficiency and J retirement stage 39 compares the oxygen deficiency detection level determined in the microcomputer 28 according to the combustion amount with the analog voltage input from the combustion state detection means 38 to the AN3, The configuration is such that a signal indicating whether combustion is abnormal or normal is sent to the combustion control means 38.

FIG. 2 shows the block diagram of FIG. 1 in a concrete circuit diagram. First, the room temperature detecting means 33 is composed of a room temperature detecting element 22 and a suitable resistor 23, and the temperature setting means 34 is composed of a suitable resistor 24, 25 and a variable resistor 26 for setting the room temperature. And combustion state detection means 3
Similar to the conventional example 8, an AC power source 12, a resistor 13, and a capacitor 16 are connected between the burner case 11 and the frame rod 10.
It is constructed by connecting a parallel circuit of 14 and 15 resistors. Further, the microcomputer 28 is ANl, AN
2. , a comparison section 27 that compares the inputs from the AN3, a ROM 27a that processes the signal from this comparison section 27 according to a predetermined program, and this ROM 27.
RAM 27b that performs necessary processing during the processing of a.
These combinations constitute the combustion amount determining means 35, the combustion control means 36, and the oxygen deficiency determining means 39 described in the block diagram. And the above ROM 27
As will be described in detail later, a program that determines strong twist firing or weak combustion based on the signals compared by the comparing section 27 and an oxygen deficiency detection level corresponding to the strong or weak combustion are preset.

The operation of the above configuration will be explained below. First, when combustion starts, input is made from ANI.If the room temperature is higher, weak combustion is selected, and if the room temperature is lower, it is switched to strong twist firing. Now, during hard twist firing, the RO of the 7-frame rod electric EEVaH microcomputer 28 input from AN3
It is compared in the comparison section 27 with the oxygen deficiency detection level v2 during strong twist firing, which is set in advance in M27a. Next, the weak combustion O7'tEEVa is compared with the oxygen deficiency detection level V 1 (Vl (V2 )) set in advance in the ROM 27a of the microcomputer 28.

This will be explained in more detail using chart 70 in FIG. A combustion amount setting routine 30, a combustion control routine 31, and an oxygen deficiency detection routine 32 are provided at arbitrary locations in the main routine. First, in the combustion amount setting routine, the room temperature data input from ANl and the setting data input from AN2 are compared in step 30&, and in step 30b, if the room temperature is lower than the set temperature, strong combustion data is set, and vice versa. If they are larger or equal in step 30c, the weak combustion data is sent to the combustion control routine 31, and the combustion control routine 31 performs combustion control based on the respective data. On the other hand, in the oxygen deficiency determination routine 32, it is first determined in step 32 & whether the current combustion amount is strong twist firing or weak combustion, and if it is weak combustion, R is determined in step 32b.
The oxygen deficiency detection level v1 at the time of weak 1 combustion, which is previously set in the ROM 27a, is stored in the oxygen deficiency level region v02, which is previously provided in the OM 2 Ta.

Next, if the combustion is not weak, do the same as above and step 32.
At c, the oxygen deficiency detection level v2 is stored in the oxygen deficiency level area VO2. In step 32d, step 32b or 32c
Oxygen deficiency level Vo2 (V 1 or V2
) and the 7 frame rod data Va input from AN3, Va ) Vo 2 (Vl or //iV
In the case of 2), the process of the oxygen deficiency determination routine 32 is completed as normal combustion, and the routine returns to the normal routine, but if Va≦Vo2(
Vl or V2), it is determined that there is an oxygen deficiency,
32e oxygen deficiency treatment (for example, combustion stop treatment) is performed.

As described above, in this combustion detection device, the oxygen deficiency detection level is corrected and changed according to the combustion state, so that malfunctions due to the extremely low combustion amount (decrease in the 7-ramrod output) are eliminated.

FIG. 8 shows another embodiment, in which the oxygen deficiency detection level is also corrected depending on the room temperature. That is, the oxygen deficiency determination means 3 of the embodiment shown in FIG.
9, a temperature correction means 39a for correcting the oxygen deficiency detection level according to the indoor temperature is added.

The operation of this embodiment will be explained below using the flowchart shown in Figure @9. The chart 70 in FIG. 9 has a configuration in which temperature correction processing is added to the oxygen deficiency determination routine shown in FIG. 3 of the above embodiment. Now, if the room temperature input from AN2 becomes lower than the temperature at which the 7 frame rod voltage drops (for example, 16 degrees Celsius) due to the influence of the room temperature, the oxygen deficiency detection level will also be lowered each time the room temperature drops. become. That is, if the room temperature is below the temperature (16°C) that requires temperature correction in step 32f, Vo2 is adjusted in step 32g by the amount V (16 - room temperature) expressed as a function of the difference between 16°C and the room temperature. =Vo2 V (16-room temperature).

Further, if the temperature does not require correction (17° C. or higher), step 32g is not performed and the process moves to step 32d.

As described above, according to this embodiment, even if the seven-frame rod output decreases due to a drop in room temperature, the oxygen deficiency detection level is lowered accordingly, so even if combustion is performed indoors at an extremely low temperature, oxygen deficiency will be detected incorrectly. This has the advantage that there is no need to worry about this happening.

In each of the above embodiments, the combustion amount was divided into two stages: strong twist firing and weak combustion, but if the combustion width is wide and the combustion switching is more frequent, the oxygen deficiency detection level may also be changed accordingly. It is possible to perform further correction in multiple stages.

Effects of the Invention As is clear from the description of the embodiments, the present invention corrects the oxygen deficiency detection level according to the amount of combustion, so it is possible to accurately detect oxygen in a wide combustion range from strong twist firing to weak combustion. Oxygen deficiency detection can be performed, and as a result, there is no need to worry about malfunction due to oxygen deficiency, so combustion can be varied over a wide period of time. Furthermore, if the oxygen deficiency detection level is corrected depending on the room temperature as in this embodiment, even in combustion in a low temperature environment,
It is possible to provide an excellent combustion detection device that can accurately detect oxygen deficiency.

[Brief explanation of drawings]

Fig. 1 is a block configuration diagram of a combustion detection device according to an embodiment of the present invention, Fig. 2 is a circuit diagram of the device, Fig. 3 is a 70-chart for explaining the operation, and Fig. 4 is a cross section of a combustion appliance. figure,
FIG. 5 is a sectional view of the burner of the same combustor, FIGS. 6 and 7 are characteristic diagrams of the seven-frame rod voltage Va, and FIG. 8 is a block diagram of a combustion detection device in another embodiment of the present invention. 9
The figure is a flowchart for explaining the same operation, and FIG. 10 is a conventional circuit diagram. 33... Room temperature detection means, 34... Temperature setting means, 35... Combustion amount determining means, 36...
... Combustion control means, 38 ... Combustion state detection means, 39 ... Oxygen deficiency determination means, 39a ...
...Temperature correction means. Name of agent: Patent attorney Toshio Nakao and one other person 111 Presented by Kendoko 3rd --- Keishoku Shoichi 36 -- Kousaku Misaki 1 II 38-Hunxia Shisha subsidiary 37-
--Acid Mataka Ashikoyaku Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9

Claims (2)

[Claims] (1) A temperature setting means for setting a desired temperature, a room temperature detection means for detecting the temperature in the heated room, and a combustion amount determining means for determining the combustion amount based on the signals from the room temperature detection means and the temperature setting means. , combustion control means for controlling the combustion of the burner to the combustion amount determined by the combustion amount determining means;
Combustion state detection means for detecting the combustion state of the burner, and oxygen deficiency detection based on a signal from the combustion state detection means, and a detection level of the oxygen deficiency detection based on a signal from the combustion amount determination means. A combustion detection device comprising an oxygen deficiency determining means to be changed. (2) The combustion detection device according to claim 1, wherein the oxygen deficiency determination means is configured to change the oxygen deficiency detection level based on the signal from the temperature detection means as well as the signal from the combustion amount determination means.