JPH0555766B2 - - Google Patents

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 In general, indoor open-type combustors such as oil fan heaters use indoor air as combustion air, so if combustion continues for a long time in a closed room, an oxygen-deficient state will occur, causing abnormal combustion such as red flames. A situation occurs in which carbon oxide is generated and poses a threat to human life.
For this reason, it has recently become common practice to provide this type of combustor with an oxygen deficiency detection device that issues an alarm or stops combustion when oxygen deficiency is detected.

For example, an oil fan heater has an oil tank 3 and a burner unit 4 provided within an exterior 1 and a base 2, as shown in FIG. The combustion gas A combusted in the burner unit 4 is blown out along with room air B from the front louver 7 as warm air C by a fan 6 attached to a blower motor 5, and is provided for room heating. FIG. 6 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 installed in the flame F and the burner case 11, and the flame F
The rectification phenomenon is used to check the state of the flame F and detect oxygen deficiency. A circuit is formed between the flame rod 10 and the burner case 11 as shown in FIG. That is, the potential Va at point a of the circuit consisting of the AC power supply 12, resistors 13, 14, 15, the capacitor 16, the burner case 11, and the flame rod 10, the DC power supply 19, the resistor 20,
Comparators 23 and 24 compare the potential Vb at point b and the potential Vc at point c of the circuit consisting of 21 and 22, and the current due to the rectification phenomenon of the flame between burner case 11 and flame rod 10 flows into capacitor 16. It is charged and the potential Va at point a changes.

The operation of the combustion detection device configured as described above will be described below. First, when no ignition occurs, the potential Va at point a is O, and the potential Vb at point b and the potential Vc at point c are higher than Va, and the outputs of comparators 23 and 24 become "H". Gives an unignited signal. Next, when ignition occurs and the combustion state is good, the charge in the capacitor 16 increases, and the potential Va at point a becomes higher than the potential Vb at point b and the potential Vc at point c, and the comparators 23 and 24 The output becomes "L", and the ignition signal and normal combustion signal are input to the control device 25.
Now, as the combustion condition deteriorates and oxygen deficiency begins to occur, the rectification phenomenon of the flame rod decreases, and eventually Va<
When it becomes Vc, the output of comparator 23 is “H”
Then, an oxygen deficiency detection signal is given to the control device 25 to control each load 26.

Problems to be Solved by the Invention However, in the above conventional configuration, the rectification phenomenon of the flame rod is good during strong combustion, and a sufficient flame rod voltage Va can be obtained, but during low combustion, the flame F is Since the flame rod is in close contact with the flame port) 8, the influence of the flame on the flame rod is extremely small, so the flame rod voltage drops below the oxygen deficiency detection level as shown in Figure 7, and oxygen deficiency detection is activated even though combustion is normal. A malfunction such as this occurs. This can be solved to some extent by moving the installation position of the flame rod 10 closer to the mesh (flame port) 8, but in this case, the flame rod will come into contact with the inner flame (incomplete flame) during strong combustion. , it becomes impossible to obtain a normal flame rod output voltage. Further, a slight thermal deformation of the flame rod causes the inconvenience that the mesh (flame port) 8 comes into contact with the flame rod 10. Furthermore, it is possible to lower the oxygen deficiency detection level in a low combustion state, but in this case, there is a problem that the oxygen deficiency detection is activated even in a slight lift combustion or yellow flame combustion.

The present invention is intended to solve such problems, and is aimed at making it possible to reliably detect oxygen deficiency even during low combustion.

Means for Solving the Problems In order to achieve this object, the combustion detection device of the present invention includes a first timer means that is activated upon entering the low combustion state, and a first timer means that is activated after the first timer means has counted up. A second timer means is provided, and when the first timer means is activated, it only detects abnormal combustion such as lift combustion and yellow flame combustion, and detects misfire, and at the same time when the second timer is activated. The structure is such that oxygen deficiency is determined by forcibly increasing the amount of combustion to increase the flame's influence on the flame rod.

Operation According to the above-mentioned structure, the present invention does not perform oxygen deficiency detection for a certain period of time even if the detection voltage of the flame rod decreases during low combustion, but once performs strong combustion for a short period of time to detect oxygen deficiency. Therefore, it is possible to prevent malfunctions such as when oxygen deficiency detection is activated during normal combustion, thereby improving detection accuracy and equipment safety.

Embodiment An embodiment 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 Figure 1,
AN1, AN2, AN3 are analog input terminals in the microcomputer 27 for combustion control.
The analog voltage can be directly read, and each is connected to the temperature setting means 28, the room temperature detection means 29, and the combustion state detection means 32. On the other hand, inside the microcomputer 27, the temperature setting means 28
The analog voltage from the temperature detecting means 29 is input from AN1 and the analog voltage from the temperature detecting means 29 is input from AN2, respectively, and the combustion amount determining means 30 compares the two to determine the combustion amount. The combustion control means 31 causes combustion to occur through the combustion control means 31 based on the combustion amount. The analog voltage from the combustion state detection means 32 is inputted from the AN3, and the combustion state determination means 3
3, oxygen deficiency etc. is determined. At this time, if the combustion amount determined based on the combustion amount is weak, the first timer 39 is started;
After counting up, the second timer 40 is started, and a combustion state suitable for each state is determined (described in detail later).

FIG. 2 shows a concrete circuit diagram of the block diagram of FIG. 1. First, temperature setting means 28
is composed of suitable resistors 34, 35 and a temperature setting variable resistor 36, and the room temperature detection means 29 is composed of a room temperature detection element 37 and a suitable resistor 38. The combustion state detection means 32 has an AC power source 12, a resistor 13, and a capacitor 16 between the burner case 11 and the flame rod 10, as in the conventional example.
In addition, resistors 14 and 15 are connected to each other. Furthermore, in the microcomputer 27, the control procedures of the combustion amount determining means 30, the combustion state determining means 33, the combustion control means 31, the first timer means 39, the second timer means 40, etc. explained in the block diagram are R O The RAM 42 performs processing required during the processing of the ROM 41. As will be described in detail later, the R O M41 has a program that determines strong combustion or low combustion based on the signals input from analog inputs AN1 and AN2, as well as a program that determines oxygen deficiency according to the ignition/misfire level and combustion amount. level, and first timer means 39;
The initial value of the second timer means 40 is set in advance.

The operation of the above configuration will be explained below. First, when combustion starts, the signal of the room temperature detection element 37 input from AN2 and the signal of the room temperature setting variable resistor 36 input from AN1 are R O M
A comparison is made on a program preset in the 41, and if the room temperature is higher, the combustion is switched to low combustion, and if the room temperature is lower, the combustion is switched to strong combustion. Furthermore, in the case of low combustion, the first timer means 39 is started, and when the first timer means 39 times up, the second timer means 40 is started, and while the second timer means 40 is started, the power is forcibly increased. The oxygen deficiency level is determined only during strong combustion, and only the abnormal combustion level, which is set to a level lower than the oxygen deficiency level, is detected during low combustion.

This will be explained in more detail using the flowchart shown in FIG.

A combustion amount determination routine 43 is provided at an arbitrary location on the control program, and the combustion amount determination routine 4
In step 3, the current room temperature and the set temperature are first compared, and if the room temperature is less than the set temperature, strong combustion is performed and the room temperature determination routine is exited. If the room temperature is set to ≧, it is determined whether the second timer means 40 is currently operating, that is, it is judged from the forced strong combustion, and if the forced strong combustion is in progress, it is determined whether the second timer means 40 has timed up, and whether or not the time has been up. If not, continue forced strong combustion, and if time is up, set low combustion,
The first timer means 39 is activated and the combustion amount determination process 43 is exited. Next, if the second timer means 40 is not in operation, low combustion is set and it is determined whether the first timer means 39 is in operation. If the first timer means 39 is in operation, the first timer means 3
9 determines whether or not the time is up, and if the time is up, the second timer means 40 is activated to perform forced strong combustion, and if the time is not up, the combustion amount determination routine continues with low combustion. Pass through 43. First timer means 3
9 is not in operation, the first timer means 39
The configuration is such that the combustion amount determination routine 43 is exited by activating the combustion amount determining routine 43.

Next, the combustion state determination routine 44 after the combustion amount determination routine 43 will be explained with reference to FIG. In the combustion state determination routine 44, the voltage Va from the combustion state detection means is compared with the ignition/misfire level set in advance in the ROM 41, and if it is below the ignition/misfire level, misfire/non-ignition processing is performed. Go and
The combustion state determination routine 44 is exited. Va arrived/
If it is higher than the misfire level, it is determined whether or not the first timer means 39 is activated, that is, whether low combustion is being performed, and if it is not low combustion (if strong combustion is being performed), the R The oxygen deficiency level is compared with the oxygen deficiency level preset in the O M41, and if it is below the oxygen deficiency level, oxygen deficiency treatment is performed, and if it is greater than the oxygen deficiency level, combustion is determined to be normal and the combustion state determination process 44 is exited. Next, when the first timer means 39 is activated, that is, when low combustion is occurring, Va and the abnormal combustion level, which is set to a level lower than the oxygen deficiency detection level previously set in the ROM 41, are set. Compare with
If Va≦abnormal combustion level, abnormal combustion processing is performed, and if Va>abnormal combustion level, combustion is determined to be normal and the combustion state determination routine is exited. Then, the routine starting from the comparison of the room temperature and the set temperature described above is repeated.

As described above, according to this embodiment, even if the combustion amount is low and the output of the flame rod becomes unstable,
After a certain period of time, strong combustion is forced for a certain period of time, and the output of the flame rod is maintained at a good level to determine oxygen deficiency. Oxygen deficiency can be detected.

In the above embodiment, the amount of combustion was divided into two stages: strong combustion and low combustion. However, in cases where the combustion range is wide and combustion switching is more frequent, the oxygen deficiency detection level may be set in multiple stages. It is also possible to set the combustion level to a certain combustion level and, when combustion continues for a certain period of time below a certain combustion level, to forcibly switch to an arbitrary combustion level that provides a good flame rod output.

Effects of the Invention As is clear from the description of the embodiments above, the present invention constantly detects ignition and misfire during combustion, and also performs yellow combustion and lift at least at the second level during low combustion when the output of the flame rod is unstable. Combustion is detected, and if low combustion continues for a certain period of time, the combustion level is forcibly set to a level where good flame rod output can be obtained, and oxygen deficiency detection is performed, so the flame rod output cannot be obtained sufficiently. Even if low combustion continues, highly safe combustion detection can be performed.

In addition, since yellow flame combustion and lift combustion are detected even during low combustion, the low combustion period can be set for a long time, and the average combustion amount during low combustion does not increase too much. It is possible to reduce the frequency of strong combustion just for the purpose of combustion, which also reduces combustion noise and improves usability.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a combustion detection device according to an embodiment of the present invention, FIG. 2 is a circuit diagram of the same device,
Figures 3 and 4 are flowcharts for explaining the operation;
FIG. 5 is a sectional view of the combustion appliance, FIG. 6 is a sectional view of the burner of the combustor, FIG. 7 is a characteristic diagram of flame rod output voltage, and FIG. 8 is a conventional circuit diagram. 28... Temperature setting means, 29... Room temperature detection means, 30... Combustion amount determining means, 31... Combustion control means, 32... Combustion state detection means, 33... Combustion state determination means, 39... First timer means, 40
...Second timer means.

Claims (1)

[Claims] 1. A temperature setting means for setting a desired temperature, a room temperature detection means for detecting the indoor temperature, a combustion amount determining means for determining a combustion amount based on a signal from the temperature setting means, and a combustion amount determined by the combustion amount determining means. a combustion control means for controlling the combustion of the burner according to the combustion amount determined by the flame rod; a combustion state detection means for detecting the combustion state of the burner by a change in the output voltage from the flame rod; and a combustion amount determined by the combustion state detection means. A first timer means is activated when combustion is low, and a second timer means is activated after the first timer means times out to forcibly increase the amount of combustion. The means includes a first set level that always detects ignition and misfire of the combustion flame during combustion, and a second set level that is set at a higher level than the first set level and detects abnormal combustion such as yellow flame combustion and lift combustion. and a third setting level for detecting oxygen deficiency, which is set at a higher level than the second setting level, and when the first timer means is activated, detection is performed at the second setting level. The combustion detection device is configured to perform detection at a third set level while the second timer means is activated.