JPH0223770B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a combustion control device for oil fan heaters and the like.

Structure of a conventional example and its problems A conventional combustion appliance, for example, an oil fan heater, is surrounded by an exterior 1 and a bottom plate 2, and is provided with a fixed tank 3 and a burner 4, as shown in FIG. Combustion gas A burned in the burner 4 is blown out as warm air C from the louver 7 together with room air B by a fan 6 attached to a blower motor 5, and is used for heating the room.

FIG. 3 shows an example of a control circuit for such a combustor. In FIG. 3, a current fuse 9 is connected in series to the AC power supply 8, and a microcomputer (hereinafter referred to as microcomputer) is connected between the bus a and the bus b connected to the other end of the AC power supply 8. 11, a series circuit between the heater 13 for vaporizing the kerosene supplied to the burner 4 and the contact 12a of the relay 12, and the blower motor 5 and the burner 4.
a parallel circuit of the burner motor 14 that sends combustion air into the interior, and a series circuit of the contact 15a of the relay 15;
A pump circuit 17 that supplies kerosene to a vaporizing chamber (not shown) in the burner 4; The parallel circuit and the series circuit of the contact 18a of the relay 18 are connected in parallel. Further, the control circuit 10 is supplied with power by stepping down and insulating the AC voltage applied between the bus lines a and b using a power transformer 19. The secondary side of the power transformer 19 is a diode bridge 2.
The base of a transistor 22 is connected to one AC terminal side of the diode bridge via a resistor 21. Furthermore, the collector of the transistor 22 is connected to the microcomputer 11.
is connected to input terminal Si. Bus line C output from the positive terminal side of the diode bridge 20
After the smoothing capacitor 23, the relay 12 driven by the transistor 24, the relay 15 driven by the transistor 25, the relay 18 driven by the transistor 26, the display circuit 27, and the power failure detection circuit 28 are connected in parallel, DC stabilized power supply 2
It is connected to the input terminal side of 9. The output side of the DC stabilized power supply 29 is connected to the microcomputer 11 during a power outage via a diode 30 for preventing current backflow during a power outage.
This is the bus line d of an auxiliary power source (hereinafter referred to as a backup power source) 31 that supplies power to the auxiliary power source. A backup power supply 31 connected to one end of the bus d includes a current limiting resistor 32 and large capacity capacitors 33, 3.
It consists of 4.35 series circuits. Bus line d
The switch circuit 36, which is one load connected to the kerosene, includes an operation switch 37 that turns the operation ON and OFF, a refueling switch 38 that detects the amount of kerosene remaining in the fixed tank and opens when the amount falls below a certain level, and a fuel supply switch 38 that is connected to the bottom of the fixed tank. The water switch 39, which opens when the amount of accumulated water is detected and exceeds a certain level, and the anti-seismic switch 40, which opens when there is vibration such as an earthquake, are turned ON and OFF.
It is connected to the microcomputer 11 via signal lines e and f to output the status to input terminals K0 and K1 of the microcomputer 11. In addition, the input terminal K2 of the microcomputer 11
A flame rod circuit 41 for detecting conditions such as combustion ignition and misfire is connected to the burner 4 which is heated by the heater 13.
Burner thermistor 4 detects the temperature of the vaporizing section inside the burner thermistor 4.
The connection point between the resistor 2 and the resistor 43 is connected, and the potential at the connection point is input. Reference numeral 44 denotes a clock display, and the microcomputer 11 counts the number of clocks input to the input terminal Si of the microcomputer 11 and converts it into a time display.

Next, the operation of the above configuration will be explained. First, when the outlet is inserted and the AC power supply 18 is supplied, the control circuit 10 is energized, and the microcomputer 11 divides the constant frequency determined by the reference oscillator 45 into an appropriate frequency, and presets the frequency according to the divided frequency. The program starts to run one step at a time from the beginning. The operation will be explained based on the flowchart shown in FIG.

First, in step 80, the operation of the internal timer of the microcomputer 11, that is, the timer that increases the count value by one each time one command of the program is executed, regardless of the contents of the program, is started. Next, step 81 checks the value of the first counter, and if the value of the first counter indicates a value of 500, proceed to flow (a), otherwise branch to proceed to flow (b). do the work. The first counter will be explained later.
The value is set to increase by 1 every 2 ms, and if the value of the first counter is 500, it means that the flow (a) progresses once per second. Flow (A) includes a processing group for determining the frequency of the AC power source 8, in which the value of the second counter accumulated as a result of the work in step 85, which will be described later, is checked in step 90, and the value of the second counter is Depending on whether it is larger or smaller than 55, either step 91 that performs 60 Hz processing or step 92 that performs 50 Hz processing is selected. In step 93, the values of the first and second counters are returned to their initial values. Step 82 following the confluence of flow (a) and flow (b) involves checking the value of the internal timer, repeating step 82 until the value of the internal timer shows a value of 2ms, and when it reaches 2ms. Go with the flow (c). In other words, the flow (c)
The subsequent step 83 is processed every 2ms. In step 83, the value of the first counter is incremented by one. In step 84, the value of the internal timer is returned to its initial value. In step 85, the clock input to the input terminal Si of the microcomputer 11, that is, the input signal changes from "H" to "L".
, detects a change from “L” to “H”,
The value of the second counter is incremented by one every clock. Step 86 is input terminal K3
It detects whether or not there is a power outage based on the input of Check the input status to K3.
Then, in the event of a power outage, proceed to flow (d), perform operation stop work in step 87, turn off the operation lamp 27a and turn on the reset lamp 27b in step 88, and process the abnormality so that it will not restart automatically when the power outage returns. Do the work of time.

If a power outage is not detected, the flow advances to step 89 (e), and a series of processes executed during normal operation are performed. That is, when the operation switch 37 is turned on, the operation lamp 27a lights up and at the same time the relay 12 is excited and the heater 13 is energized. When the burner thermistor 42 detects that the temperature of the vaporization part in the burner 4 has risen to a predetermined temperature, the relay 15 is energized to turn on the burner motor 14 and the blower motor 15. Relay 1 after a certain period of time
8, the pump circuit 17 and the igniter 16 are activated.
Turn on. The igniter 16 discharges electricity for a certain period of time after being energized, and then automatically stops. Here, the ignition state is detected by the flame rod circuit 41, and if there is no ignition, the ignition operation is performed again, or an abnormality is determined and the operation is stopped.

Next, a case where a power outage occurs will be explained. First, the power failure detection circuit 28 connects the base terminal of a transistor 28c to a bus line C via a Zener diode 28a connected in series with a resistor 28b, and connects the collector terminal of the transistor 28c to a bus line d through a pull-up resistor 28d. It is connected to the K3 input terminal of No. 11.

When a power outage occurs in the above configuration, the voltage on the bus c decreases, and this voltage is transferred to the Zener diode 2.
When the Zener voltage of 8a is lower than that of transistor 2,
Since no current flows into the base terminal of the transistor 8c, the transistor 28c is turned off, the input terminal K3 becomes "H", and a power outage is detected in step 86. In general, power outages can be broadly classified into two types, one of which is instantaneous power outages that occur mainly due to lightning or the like, and the duration of voltage loss is approximately several tens of milliseconds to several seconds. The other case is when the duration of voltage loss is several seconds or more due to failure or modification of power equipment, or movement of the oil fan heater. In the above circuit configuration, although there are some differences depending on the load conditions connected to bus c during a power outage, if there is an instantaneous power outage of approximately 50 ms, the potential of bus c is sufficient for the microcomputer 11 to determine that there is a power outage. decreases to Momentary power outages have little impact on daily life and are often spent without even realizing that they have occurred, but in France there are 560 cases of momentary power outages of 0.05 seconds each year, and cases of momentary power outages of 0.1 seconds. It has been reported that as many as 250 cases of this occur each year (according to Electric Kyodo Research Vol. 27, No. 1). Conventional control devices respond sensitively to these (instantaneous power outages), frequently detecting abnormalities, and must be restarted each time, making them inconvenient to use. In particular, even if the machine is set to run automatically when you wake up in the morning, if there is even one slight momentary power outage, it will stop abnormally, and when you wake up in the morning, it will not be running and you will have to restart it manually. There were other problems.

Purpose of the Invention The present invention was made in view of the above-mentioned problems, and an object of the present invention is to continue operation without abnormal stoppage in the case of a power outage within a certain period of time.

Structure of the Invention In order to achieve the above object, the present invention includes a backup power supply that supplies power to a microcomputer during a power outage, a power outage detection circuit that detects a power outage, and an igniter that discharges electricity for a certain period of time when power is supplied. The microcomputer is configured to measure the duration of a power outage and to stop operation if the power outage continues for a predetermined time or longer, and to continue operation if the power outage is within a predetermined time.

DESCRIPTION OF THE EMBODIMENTS One embodiment will be described below with reference to FIGS. 1 and 2. Parts that are the same as those of the conventional example will be given the same numbers, explanations will be omitted, and only the different parts will be explained.

First, the overall control circuit configuration is the same as the conventional one, but the microcomputer 1 which forms the main body of the control circuit 10
The operation content of 1' is different from the conventional one.

Below is the second section showing the operation contents of this microcomputer 11'.
This will be explained using the flowchart shown in the figure. In FIG. 2, step 94 checks the value of the third counter, which was processed in step 95 so that the value is incremented by 1 every 2 ms, and if the value is less than 500, the process goes to step 89. Time branches to step 87. Further, step 96 performs processing to return the value of the third counter to the initial value when it is determined in step 86 that the problem is other than a power outage, and then returns the value of the third counter to the initial value.
This allows the flow to flow to 9.

In the above configuration, normally the flow is (B) → (C) → (E) →
The loop from (H) to (B) is repeated, and the clock display is managed by performing 60Hz and 50Hz processing in flow (A) instead of flow (B) once every second. If a power outage occurs during combustion, the burner motor 14 and blower motor 5 will continue to rotate for about 10 seconds due to inertia, but
The pump circuit 17 stops supplying kerosene with a delay of about 10 milliseconds, and the combustion flame disappears. On the other hand, the potential of bus c also drops at the same time, and within several tens of milliseconds, transistor 28
c is turned OFF, and an "H" signal is input to the input terminal K3 of the microcomputer 11'. Microcontroller 1 at this time
The internal operation of 1' will be explained with reference to FIG. First, in step 86, when the input terminal K3 is checked as "H",
Proceeding to step 94, the value of the third counter is checked. And if the value of the third count is 500 or more, flow
If it is less than 500, proceed to (f). The value of the third counter increases by one at step 95, which is passed every 2 ms, but it is returned to the initial value at step 96 unless there is a power outage, so the value is 0 during normal times. However, if a power outage is detected in step 94, the flow
changes to flow (f). Flow (f) is executed 499 times, that is, if the power outage continues for a while, the value of the third counter becomes 500 on the 500th time, so after step 94 is executed, the flow changes to flow (g). The third counter increments by 1 every 2 ms, so counting 500 times equals 1 second. That is, steps 87 and 88 are executed 1 second after a power failure occurs and the input terminal K3 becomes "H". Ru. Once steps 87 and 88 are executed,
The microcomputer 11' handles the abnormality and does not restart operation unless a manual start operation is performed when the power is turned on again. However, in the case of a momentary power outage of less than 1 second, input terminal K3
changes to "L" and changes to flow (E). Then, in step 89, the operation before the power outage is continued. In addition, in the case of a momentary power outage within 1 second as mentioned above,
Since the burner motor 14 and the blower motor 5 are re-energized while continuing to rotate due to inertia, the number of rotations does not decrease enough to cause a problem. In addition, the igniter 16 has a built-in timer function, and when the power is re-energized, the above-mentioned timer is always started and the discharge is performed for a certain period of time. Therefore, when the power is re-energized, the pump circuit 17 starts operating and the igniter is re-ignited, and combustion continues from then on. do. Moreover, the burner 4 has a very large heat capacity, so there is almost no temperature drop due to momentary power outage, and smooth re-ignition can be obtained.

Effects of the Invention As described above, according to the present invention, even if a short-term instantaneous power outage occurs, continuous operation is possible without stopping even if a power outage is detected. Moreover, in the event of a power outage exceeding a certain level (for example, when moving to another room), the operation will be stopped.
It is possible to satisfy both safety and ease of use by preventing dangerous situations such as oil leakage and explosive ignition due to poor re-ignition.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a combustion control device according to an embodiment of the present invention, FIG. 2 is a flowchart explaining the same operation, and FIG. 3 is a circuit diagram of a conventional combustion control device.
Figure 4 is a flowchart explaining the same operation, and Figure 5 is a flowchart explaining the same operation.
The figure is a cross-sectional view of an oil fan heater. 4... Burner, 11'... Microcomputer, 28... Power failure detection circuit, 31... Auxiliary power supply.

Claims (1)

[Claims] 1. A pump that supplies fuel to the burner, a pump circuit that drives the pump, an igniter with a built-in timer circuit that discharges for a certain period of time when power is supplied, and is reset when the power is cut off, and a microcomputer. The control circuit is equipped with an auxiliary power supply that operates to supply power to the microcomputer at least in the event of a power outage, and a power outage detection circuit that detects a power outage, and the microcomputer is equipped with a power outage detection circuit that detects a power outage. A combustion control device comprising a timer that measures the duration, and when the value of the timer is below a certain value, combustion and operation are continued, and when it is greater than the above value, the operation is stopped.