JPH02126016A - Warm air heater control device - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control device for a hot air heater equipped with an evaporative burner.

Conventional Technology Conventionally, the mixing ratio of vaporized fuel oil and combustion air in a combustor has been determined in advance by determining the optimal ratio when designing the combustor, although it varies slightly depending on the amount of combustion, such as strong combustion or weak combustion. This is determined so that combustion always takes place at a predetermined mixing ratio during ignition and during normal combustion.

FIG. 5 is a schematic diagram showing the structure of a conventional oil heating device.

101 is a fuel tank, and fuel oil is sucked up by an electromagnetic pump 102 and fed under pressure to a carburetor 103. vaporizer 1
03 is heated by the heat generated by combustion and the heater 104, and after the fuel oil is vaporized here, it is mixed with the combustion air supplied from the combustion air supply device 105 in the mixing chamber 106, and then in the flame port 107. A flame 108 is formed. The combusted exhaust gas exchanges heat with the indoor air through the combustion tube 109 and the radiator 11O to heat the room, and is then exhausted to the outdoors.

FIG. 6 shows a conventional control circuit, in which 111 is a power supply;
A control unit 112 performs combustion control by controlling the temperature of the heater 104 and controlling various timings of relays and the like. The control unit 112 first preheats the carburetor 103 by turning on the relay 113 at the start of operation, and when the preheating is completed, turns off the relay 113 and turns on the relay 114 to turn on the combustion air supply device 105, the electromagnetic pump 102, and The igniter 115 is energized and ignites and burns. The combustion air supply device 105 is composed of a motor provided with taps a and b for selecting strong rotation and weak rotation, and the electromagnetic pump 1
02 is provided with terminals a' and b' that can change the discharge amount in two stages.

The relay 116 is a two-circuit, two-contact relay, and the contacts are a,
When closed to the a' side, the combustion air supply device 105 rotates strongly;
The electromagnetic pump 102 is set to a large flow rate to perform strong twist firing.

Conversely, if the contact of the relay 116 closes on the b' side, weak combustion will occur.

As described above, the conventional control device for hot air heaters was designed to supply predetermined combustion air and fuel oil according to the amount of combustion for strong twist firing or weak combustion, respectively. .

Problems to be Solved by the Invention However, in the conventional configuration described above, the amount of combustion air supplied by the combustion air supply device 105 and the amount of fuel oil discharged from the electromagnetic pump 102 are set in advance according to the amount of combustion. When the mixing chamber 106 is not sufficiently warmed up at the start of combustion, some of the vaporized fuel oil condenses before reaching the flame opening 107, resulting in a slightly lifted combustion and an odor. On the other hand, as sufficient vaporized fuel oil with combustion heat recovered is obtained in the mixing chamber 106, combustion becomes yellow-flame combustion and soot is more likely to be generated.

The present invention solves such conventional problems, and by detecting the temperature of the flame port, it prevents the combustion state at the time of ignition from changing depending on the state of heat distribution in the mixing chamber and the length of combustion time. The first purpose is to always obtain a stable combustion state. Furthermore, a second purpose is to enable the use of a relatively inexpensive thermistor for detecting the temperature of the flame nozzle, and to ensure safety by detecting an abnormality in the supply amount of combustion air using the thermistor.

Means for Solving the Problems In order to achieve the above objects, the control device for the hot air heater of the present invention mixes fuel oil and combustion air, and mixes fuel oil and combustion air on the wall surface of the mixing chamber that has a correlation with the temperature of the flame opening. The flame outlet temperature detection means is provided, and a combustion control section is provided which changes the mixing ratio of the amount of fuel oil and the amount of combustion air in accordance with the output from the flame outlet temperature detection means.

Effect of the Invention With the above-described configuration, the present invention changes the ratio of the amount of combustion air to the amount of fuel oil depending on the temperature of the flame port immediately before ignition, so that stable ignition and combustion can be achieved regardless of the temperature of the flame port. can get.

In addition, the wall surface of the mixing chamber is located close to the flame nozzle, so although it is most affected by the temperature of the flame nozzle, it is not in direct contact with the flame, so it is maintained at a relatively low temperature of 200℃ to 300℃. This makes it possible to use inexpensive medium-temperature thermistors.

Furthermore, the thermistor can also be used to detect abnormalities such as insufficient air volume.

Embodiments Hereinafter, embodiments of the present invention will be explained based on FIGS. 1 to 4. FIG. 1 is a block diagram of this embodiment, which is composed of a burner using opposed flames, and FIG. 2 is a horizontal cross-sectional view of the burner viewed from above. 1 is a frame, 2 is a fuel tank, 3 is an electromagnetic pump whose amount of fuel discharged changes according to the applied pulse frequency, and the fuel is ejected to the burner 5 via a nozzle 4. 7 is the nozzle 4 mentioned above. This is a combustion air supply port that supplies combustion air from around the periphery of the combustion air, and is in communication with the combustion air supply device 6. 8 is a long and narrow vaporizer, and a heater 9 buried in the bottom vaporizes the fuel. 8a is a heater temperature sensor for detecting the temperature of the vaporizer 8, which is attached to the bottom of the vaporizer 8. 10 is a heater temperature sensor for detecting the temperature of the vaporizer 8, and is attached to the bottom of the vaporizer 8. It is a mixing chamber for mixing the mixed gas, and also serves as a passage for supplying the mixed gas to the combustion section 11. 12 is a flame temperature detector such as a thermistor disposed so as to be in contact with the outer wall surface of the mixing chamber 10, An electrical signal obtained by converting the detected temperature is input to the control device 16. Reference numeral 13 is a flame port provided in the combustion section 11, and the mixed gas ejected from this flame port 13 forms a flame 13a.
The flame formed is detected by flame rod 14.

The control device L6 includes a flame mouth temperature detection means 17 which receives the output of the flame mouth temperature detector 12 as an input, an overheat detection section 17a that detects an abnormality in the output of the flame mouth temperature detection means 17, and a combustion amount that is sent to the electromagnetic pump 3. an electromagnetic pump control means 18 that outputs a pulse signal corresponding to a pulse signal, a combustion air control means 19 that controls the rotation speed of the combustion air supply device 6 to a predetermined rotation speed, and the heater temperature sensor 8a. a heater temperature detection means 15 that determines the temperature of the carburetor 8 detected by the flame rod 14; an ignition detection section 14a that determines the presence or absence of ignition based on a signal from the flame rod 14; the electromagnetic pump control means 18 and the combustion air control means 19. signal line S1 or S2 to each
The combustion control section 20 instructs a predetermined value according to the combustion sequence via the combustion control section 20.

The signal line S1 is an output signal that changes in accordance with information from the flame outlet temperature detection means 17, and the signal line S2 is an output signal that changes in accordance with the combustion amount. Combustion air control means 19
The signal lines s1 and s2 are selectively inputted via a switch 14b which is switched by the output of the ignition detection section 14a.

FIG. 3 shows an example of a specific circuit of the main part. Control device 1
6 is composed of a microcomputer 21 and peripheral circuits, and the microcomputer 21 shown here is
It is a so-called one-chip microcomputer that has a CPU, ROM, RAM, and input/output section. The flame mouth temperature detector 12 and the heater temperature detector 8a are connected to an input section of a microcomputer 21 via an A/D converter 22.

As a result, the flame outlet temperature detector 12 and the heater temperature detector 8
The temperature signals from a are converted into binary codes and read into the microcomputer 21. Reference numeral 23 denotes an operation switch for instructing the start of combustion, which is input to the microcomputer 21. 24 is an AC signal source 25 synchronized with the power frequency
The microcomputer 21 uses this pulse signal to determine the zero-crossing point. 26 is a semiconductor switch, and the light emitting part LE
It consists of D and a triac in the light receiving section. 27 is a relay that turns on and off the heater 9, and 28 is an igniter. 29 is a driver that drives the semiconductor switch 26, relay 27, electromagnetic pump 3, and igniter 28 connected to the output in response to an output signal from the microcomputer 21; 27a
The heater 9 and the combustion air supply device 6 are connected in parallel via the semiconductor switch 26. The rotation speed of the combustion air supply device 6 is detected by a rotation detector 31, and the microcomputer 21 performs feedback control of the rotation speed based on this rotation information.

Next, the operation of this embodiment configured as described above will be explained according to the flowchart of FIG. 4. When it is determined in step 37 that the operation switch 23 is turned on, step 3
8, by turning on the relay 27, the heater 9 is energized and preheated. Next, step 39 is a routine in which the heater temperature sensor 8a determines that the temperature of the carburetor 8 has reached approximately 180° C., and the engine 40 turns on the combustion air supply device 6 at a strong rotation speed of 245 rpm. This is the mixing chamber 1
The combustion air is supplied from the combustion air supply lower to the combustion air supply lower as shown by arrow A (Fig. 2), while being heated by the heater 9. After flowing along the direction, it passes through the mixing chamber 1o and reaches the flame outlet 1.
It flows into 3. Therefore, the combustion air warmed by the heater 9 also warms the mixing chamber 1o and the flame port 13, so the temperature of the flame port 13 is the temperature of the mixing chamber 1o detected by the flame port temperature detector 12.
almost equal to the wall temperature of When it is determined in step 41 that the temperature of the vaporizer 8 has further increased by 2'' to reach approximately 220''C, the process moves to the next step 42.Step 4
2, switch 14b is set to signal &? Connect to the ISl side (
Figure 1). That is, the rotation speed of the combustion air supply device 6 is changed to the rotation speed shown in Table 1 below in accordance with the flame mouth temperature indicated by the flame mouth temperature detection means 17. The rotation speeds in Table 1 are
It is set so that the lower the flame mouth temperature, the lower the rotation speed of the combustion air supply device 6. After waiting for 10 seconds in step 43 to stabilize the rotational speed of the combustion air supply device 60, the process moves to step 44, which is an ignition sequence.

In step 44 of Table 1, the igniter 28 is turned on, and at the same time, the electromagnetic pump control means 18 outputs a pulse signal (27 Hz) equivalent to strong twist firing to the electromagnetic pump 3 from the output section. At this time, the rotation speed of the combustion air supply device 6 is lower than the strong rotation of 245 Orpm in response to the ejection of fuel equivalent to strong twist firing, and there is a slight excess of fuel. This is because the setting takes into account that some of the vaporized fuel oil will condense before reaching the flame port 13 after passing through the mixing chamber 10. Step 45 is a routine for determining ignition. When ignited, the temperature of the flame nozzle 13 rises rapidly, but the temperature near the flame nozzle 13 does not rise as much as the temperature near the flame nozzle 13 in the vicinity where the flame nozzle temperature detector 12 is attached due to the flow of combustion air. Therefore, the correlation between the temperature of the flame port 13 before ignition and the temperature detected by the flame temperature detector 12 is no longer maintained. Step 46 is a routine for controlling combustion after ignition is detected.
b to the signal line S2. Thereby, the rotation speed of the combustion air control means 19 is changed to the rotation speed corresponding to the pulse signal output from the electromagnetic pump control means 18, and combustion stability is maintained.

In addition, even though combustion is in progress normally, the amount of combustion air supplied decreases due to some reason such as a disconnection in the combustion air supply device 6 or a clog in the combustion air supply lower, and the flame temperature detector 12 is removed. When the flow of air in the vicinity decreases, the flame temperature detector 12 begins to detect an abnormally high temperature. When the flame temperature detection means 17 continues to have a temperature equal to or higher than a predetermined temperature for 10 seconds, it determines that the supply amount of combustion air has decreased in step 47, and outputs a signal to the overheat detection section 17a. Combustion control section 2
0, it is determined that there is an abnormality based on the output from the overheat detection section 17a, and combustion is stopped.

According to the configuration of the above embodiment, the flame outlet temperature is constantly monitored during ignition, and the ratio between the amount of combustion air supplied and the amount of fuel injected from the electromagnetic pump is changed in accordance with the flame outlet temperature. Lift combustion does not occur even during a cold start when the combustion section is sufficiently cold, and yellow flame combustion does not occur during a hot start when the combustion section has already warmed up, which occurs during re-ignition, ensuring good ignition. performance will be obtained. Moreover, the flame outlet temperature detector that monitors the flame outlet temperature is not installed at the flame outlet, which is exposed to high-temperature atmosphere, but in the mixing chamber, which is relatively low temperature and has a good temperature correlation with the flame outlet.
It becomes possible to use an inexpensive general medium-temperature thermistor that is used at temperatures of about .degree. C. to 300.degree. Furthermore, it is safe because it also detects abnormalities in the combustion air.

In the above embodiment, as a mixture ratio control method of changing the mixing ratio between the amount of vaporized fuel oil and the amount of combustion air, the amount of fuel jetted is fixed and the combustion air supply device 6 Although this was done by changing the rotation speed of the flame, there is also a method of changing the amount of fuel ejected according to the temperature of the flame outlet. Furthermore, although the rotational speed of the combustion air supply device 6 is changed to change the supply amount of combustion air, the diameter of the combustion air supply lower may be changed in multiple stages using a damper or the like.

Effects of the Invention As described above, the hot air heater control device of the present invention provides the following effects.

1. The airflow that flows through the vaporizer, mixing chamber, and flame port before the ignition operation improves uneven heat distribution in the mixing chamber and prevents condensation on the vaporized fuel oil.

2. Normal ignition performance can be obtained even during a cold start in which ignition is performed when the flame nozzle is cold, and during a hot start in which ignition is performed when the flame nozzle is warm.

3. The mixing chamber where the flame temperature detector is installed is kept at a relatively low temperature by the cooling effect of the combustion air flow, and an inexpensive thermistor can be used.

4. Since the flame temperature detector also acts as a combustion air abnormality detector, reliability is increased and cost performance is also improved.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing one embodiment of the present invention, Fig. 2 is a sectional view of the same burner, Fig. 3 is a specific circuit diagram of the same main part, and Fig. 4 is a block diagram showing an embodiment of the present invention.
The figure is a flowchart for explaining the operation, FIG. 5 is a schematic structural diagram of a conventional warm air heater, and FIG. 6 is a control circuit diagram of the conventional hot air heater. 3... Electromagnetic pump, 6... Combustion air supply device, 8... Carburizer, 10... Mixing chamber, 12... Flame mouth temperature detector, 13...
...flame mouth, 17a... overheat detection section, 20...
...Combustion control section. Agent's name: Patent attorney Shigetaka Awano Idiot 1 famous confectionery diagram 8--all at once 4

Claims (2)

[Claims] (1) A vaporizing burner comprising a vaporizer that heats and vaporizes fuel oil, a mixing chamber that mixes at least the vaporized fuel oil and combustion air, and a flame port that forms a flame; a flame outlet temperature detection means for detecting the temperature at the flame outlet or the temperature at a location substituted for the temperature at the flame outlet; A control device for a warm air heater that includes a combustion control section that changes the air amount and mixing ratio. (2) Hot-air heating according to claim 1, wherein the flame outlet temperature detection means is attached to the wall surface of the mixing chamber of the burner, and an overheat detection section that stops combustion in response to an abnormal output from the burner outlet temperature detection means. Machine control device.