JPH0335583B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control device for an oil burner such as an oil fan heater.

BACKGROUND OF THE INVENTION In general, a control circuit for an electromagnetic pump in this type of oil combustor control device supplies kerosene by an electromagnetic pump 1 operated by two thyristors alternately conducting and non-conducting as shown in Fig. 3. It is something to do.

An alternating current voltage is applied to an oscillation circuit 3 by an alternating current 2, thereby applying a pulsed voltage to the electromagnetic pump 1 to operate it. The configuration of this oscillation circuit is that diode 4 → resistor 5 → point a → capacitor 6 → point b forms a closed loop, and between points a and b are electromagnetic pump 1 → point c → thyristor 7, and resistor 8 → point d → Connect two series circuits of thyristor 9. A capacitor 10 and a resistor 1 are connected between points c and d.
Connect 1 series circuit. The gate 12 of the thyristor 7 is configured to receive a signal from another control circuit 13, and a trigger element 14 is connected to the gate 15 of the other thyristor 9 from point d, and a resistor 16 is connected between the gate and cathode of each thyristor. , 17 are connected.

The operation of this circuit will be explained. AC power supply 2
When a voltage is applied from the diode 4, the resistor 5, and the capacitor 6, a DC voltage is generated between points a and b. Initially, there is no signal at the gate 12 of the thyristor 7, so the thyristor 7 is non-conductive. The thyristor 9 is triggered by the circuit of the resistor 8 -> point d -> trigger element 14 -> gate 15, so that the thyristor 9 is in a conductive state, and the connection between points d and b is shorted. At this time, capacitor 1
0, the point c side is positively charged.

In this state, if a signal is input from the control circuit 13 to the gate 12 of the thyristor 7, the thyristor 7 is turned on, and current begins to flow through the electromagnetic pump 1. At this moment, capacitor 10
The charged charge flows into the closed circuit of point c → thyristor 7 → point b → thyristor 9 → point d → resistor 11, and therefore, a reverse voltage is applied to thyristor 9 between its cathode and anode, which has been in a conducting state until now. things become non-conductive. From this point on, capacitor 1
Voltage is applied to 0 in the opposite direction from the previous one, in the order of resistor 8 → point d → resistor 11 → capacitor 10 → thyristor 7, and at the same time, the potential at point d gradually rises due to the charged charge. . The speed of this increase is determined by the characteristics of the resistor 8, resistor 11, and capacitor 10, and continues to increase until the breakover voltage of the trigger element 14 reaches V _B0 , at which point the thyristor ₉ is triggered again. and turn on. Since the capacitor 10 is charged in the opposite direction from the previous time, when the thyristor 9 turns on, the capacitor 10 → the resistor 11
→ point d → thyristor 9 → point b → the cathode of thyristor 7 → the anode of the capacitor 10 is discharged, and a reverse voltage is applied to the thyristor 7 from the cathode to the anode, and the thyristor 7 is turned off. Current continues to flow through the electromagnetic pump 1 up to this point. The time during which the oil flows (referred to as on-time) and the interval at which the thyristor 7 operates determines the amount of oil flowing. In this way, the on-time is determined by adjusting the resistor 8.

As described above, according to the circuit shown in FIG. 3, the control circuit 13
The transmitting circuit automatically applies a pulse of a certain width to the pump 1 in response to a signal from the pump 1.
The oil flow rate is determined by the width of this pulse and its period.

In this way, oil fan heaters and the like perform heating by feeding the appropriate amount of air to the set oil flow rate and causing normal combustion in the burner, and this condition is constantly monitored by a separately installed flame sensor. It is structured as follows.

Problems to be Solved by the Invention However, in this type of combustion appliance, the combustion exhaust is only clean if the amount of oil and air are appropriate, but once this balance is disrupted, many problems occur. Occur. When the amount of oil is low, a flame sensor installed separately works to stop combustion, which is usually on the safe side and does not pose a danger. However, on the other hand, if the amount of oil increases, it is very dangerous.

In particular, when the withstand voltage of the thyristor 7 becomes lower than the voltage between points a and b, it alternately turns on and off in relation to the thyristor 9, resulting in an oscillation phenomenon and the pump 1 having a higher frequency than the standard. A lot of oil will flow and be dangerous. As can be seen in the explanatory diagram of FIG. 2, under normal conditions, a regular waveform as shown in a is applied to the electromagnetic pump 1, but if, for example, the thyristor 7 has a poor withstand voltage, the waveform becomes as shown in b. The number of frequencies increases. In such a situation, the amount of fuel in the burner is large compared to the amount of air, which not only causes the flame to elongate, but also increases the content of carbon monoxide in the combustion flame, which is extremely dangerous.

In particular, with fan heaters and the like, the flames can be expected to burn out equipment and pose a danger to humans. The present invention is intended to solve these conventional problems, and has a control circuit configured to operate in a safe manner in all cases of such malfunctions.

Means for Solving the Problems In order to solve the above problems, the control circuit for the oil-burning appliance of the present invention includes a circuit of a resistor and a capacitor in series with a thyristor that is triggered and conductive by a pulse generated by another controller. is connected, and the voltage is applied to the electromagnetic pump by the transistor only during the timer period, which operates using the difference between the voltage due to the charging current of this circuit and a separately provided reference voltage. The structure is such that when the amount decreases, conduction is automatically released and the original state is restored.

Effects By having the above-mentioned configuration of the present invention, the timer circuit operates mainly using transistors, so that the circuit itself does not cause an oscillation phenomenon, as in the conventional example.

In addition, even if a component breaks down in the initial startup circuit, since it uses capacitor charging, once the charging charge reaches a certain level, it will stop at that point, and there will be no oscillation or large current. . In addition, since a transistor is used as a driver to operate the electromagnetic pump, it is completely controlled like a thyristor.
It is not a failure mode where the voltage turns on or off, but a mode where the voltage remains constant. An electromagnetic pump only discharges oil when the voltage changes from high to low, but since it does not operate at all at a constant voltage, it is completely safe to use a transistor circuit like this.

Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings. In FIG. 1, an AC power supply 2, a diode 4, a resistor 5, and a capacitor 6 constitute a DC power supply circuit between points a and b. Between points a and b, resistor 30 → point c → resistor 31 → capacitor 32 → d
Connect the series circuits of point → Zener diode 33 → thyristor 7, resistor 34 → point e → resistor 35, and electromagnetic pump 1 → transistor 36. The collector point f of the transistor 27, whose base and emitter are points c and e, is connected to a resistor 38, a point g, a resistor 39, and a point k, and the base of the transistor 36 is connected to a point g. Further, resistors 42 and 40 are connected between the gate 12 and the point b between points a and d. Further, a diode 41 is connected in parallel to the resistor 30.

The operation of this circuit is such that when a pulse from another control circuit 13 enters the gate 12 of the thyristor 7 while a DC voltage is being generated between points a and b, the thyristor 7 is turned on and the resistor 30 → point c → the resistor. The charging current of the capacitor 32 flows through the circuit 31 → capacitor 32 → point d → Zener diode 33. This current is higher than the holding current of the thyristor 7. Of course, a voltage higher than the zener voltage of the zener diode 33 is applied to the thyristor 7 from the point d. This current is the capacitor 32
The current decreases as it approaches completion. Further, due to the current, the voltage between the Zener diodes also decreases, and when the voltage becomes lower than the Zener voltage, the current of the thyristor 7 becomes 0 and the thyristor 7 is turned off. At this point, the charging current of the capacitor 32 becomes zero.
Further, from this point onwards, the charge in the capacitor 32 begins to be discharged through the resistor 42, and the potential at point d approaches the potential at point a. The potential at point e is a reference potential determined by resistors 34 and 35. The transistor 37 with its emitter at this point will have a lower potential at point c when the thyristor 7 is turned off.
It is in the ON state, and then charging is gradually carried out, and the potential at point C approaches the potential at point A, and when the current decreases and becomes higher than point d, the current at the collector point f stops flowing. Since the transistor 36 is in an ON state while a voltage is generated at point f, voltage is applied to the electromagnetic pump 1, and when the voltage at point f disappears, the voltage of the electromagnetic pump 1 becomes 0.
In this way, the ON time of the electromagnetic pump 1 is determined by the potential at point c, and therefore the ON time is determined by the resistor 31 and the capacitor 32. Therefore, the resistor 31 is constituted by a variable resistor, and the ON time is determined by the resistor 31 and the capacitor 32. It is used for time adjustment, and the electromagnetic pump will not turn on until the next pulse enters terminal 12.

Since the electromagnetic pump 1 operates in such a cycle, even if the thyristor 7 does not have a withstand pressure,
The charging/discharging phenomenon of the capacitor 32 never reaches the level of vibration. Especially when there is no withstand voltage, the capacitor 32 remains charged and the transistors 37 and 36 do not operate at all.

Further, even if the thyristor 7 is self-triggered, the discharge speed of the resistor 42 is not designed to be so fast, so the transistor 37 is not turned on and off repeatedly and does not oscillate.

Further, if the transistor 36 has a breakdown voltage failure, a constant current continues to flow through the pump 1, so that the pump 1 does not open or close. Furthermore, if the value of the resistor 5 is made as large as possible, and the value of the capacitor 6 is also made large in return, even if the transistor 36 suffers a short-circuit accident, the voltage between points a and b will be low, and the pump 1 will not operate. It disappears.

Effects of the Invention As described above, according to the present invention, oscillation does not occur unlike the conventional circuit even if the transistor connected in series with the pump is in short mode or has a similar failure.

In addition, as a characteristic of transistors, there is no turn-on phenomenon like that of thyristors, so it is completely conductive.
It is difficult to be in the OFF state. Therefore, this is the direction in which a constant current flows, and the electromagnetic pump does not operate.

Therefore, the electromagnetic pump will not operate due to a defective part or circuit, and a large amount of oil will not flow, causing a fire or contaminating the exhaust gas.

[Brief explanation of the drawing]

FIG. 1 is a control circuit diagram of the electromagnetic pump section in an embodiment of the oil combustor of the present invention, FIG. 2 is an explanatory diagram of the voltage waveform applied to the electromagnetic pump section, and FIG.
The figure is an oscillation circuit diagram of an electromagnetic pump for a conventional oil combustor. 1... Electromagnetic pump, 7... Thyristor, 13...
...Controller, 30,31...Resistor, 32...Capacitor, 33...Zener diode, 36,37...
...transistor.

Claims (1)

[Claims] 1 A circuit of a resistor and a capacitor is connected in series with a thyristor that is turned on by a pulse, and a transistor is used to apply voltage to an electromagnetic pump for fuel supply only during the timer period that operates using the difference between the voltage generated by the charging current of this circuit and the reference voltage. In addition, the thyristor is operated, and the thyristor automatically releases conduction and returns to its original state when the charging current to the capacitor decreases.