JPH0148444B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an oil burner such as an oil fan heater.

Structure of conventional example and its problems A conventional oil combustor, for example, an oil fan heater, has an oil tank 3 and a burner 4 inside an exterior 1 as shown in FIG. , the indoor air B is supplied by a blower motor 5 and a blower fan 6 attached to the back of the exterior.
At the same time, warm air C is sent into the room from the front louver 7. The combustion part of the burner 4 is as shown in Fig. 2, and the upper part of the burner base 8 has a mesh-shaped jetting port 9. Premixed vaporized oil is spouted from this mesh, and is ejected from the ignition electrode 10 into the mesh. It sparks and ignites, creating a combustion flame 11. A flame rod 12 is installed so as to hit this flame and monitor the combustion flame.

FIG. 3 shows an example of a conventional control circuit. The AC power source 13 constitutes a closed circuit including a point a, a relay contact 14, a burner heater 15, a point b, and an operation switch 16. A second relay contact 17 - a parallel circuit of the blower motor 5 and a burner motor 18 is connected between points a and b, and a third contact 19 - point c -
Connect the oil pump 20. A high voltage igniter 21 is connected between points C and b, and a control circuit 22 including a relay control and safety device is connected between points a and b. Further, a DC constant voltage source 23 generated by this control circuit forms a closed loop with a point d, a resistor 24, a point e, a resistor 25, and a point f. Another AC power supply 26 has one end connected to a protective resistor 27 - point g - resistor 28 and capacitor 2.
9 connected in parallel - point f - flame rod 12 - burner 4 form a closed loop. Note that the output point h of the operational amplifier 30, which uses points g and e as positive and negative inputs, sends a signal to the control circuit 22.

To explain the operation of this device, power switch 1
6 is closed, the control circuit 22 causes the heater 15 to raise and maintain the temperature of the vaporizer in the burner 4 at a constant temperature. Therefore, the oil sent from the pump 20 is vaporized by the vaporizer, mixed appropriately with the air sent by the burner motor 18, and is ejected from the ejection mesh 9. At this time, a spark jumps between the ignition electrode 10 and the mesh and is ignited by the igniter 21.
This flame causes a rectified current to flow through the flame rod 12 and burner 4. Therefore, a charging voltage is generated across the capacitor 29 in FIG. 3, and is determined to a certain value by the resistor 28. On the other hand, the resistance dividing point e is fixed at a constant value by the constant voltage power supply 23, but the current of the flame rod changes depending on the combustion state.
In order to explain this situation, FIG. 4 shows the states at points e and g. In other words, the potential at point e is always constant, as shown in characteristic e, but the potential at point g is as shown in characteristic g, which is O when there is no combustion, but rises to point _e1 during combustion, and the output at point h is high. Become. When there is a lack of oxygen or oil, the potential becomes lower than the reference potential at point e, and the output at point h becomes low and no longer sends a signal to the control circuit 22.

There is no problem under normal conditions like this, but when the outside temperature drops, especially from 0 to -20℃, the rate at which the air density increases and the oil flow rate is related to the amount of vaporization makes it difficult to say much. There will be too much air for combustion. Therefore, the combustion flame tends to lift, the flame-lot current decreases, and the potential at point g may be less than point e. In particular, when the oxygen deficiency level under normal conditions is defined as e, when the temperature becomes low, this value is divided as shown by the characteristic g', and becomes stable at about ₂ points. In this way, there are cases where even a normal sequence does not work. In reality, the location of point g is normal, oxygen deficient,
The position of e is well determined at the time of ignition, misfire, etc., but as the temperature gets lower, the value of the g point decreases overall, and the e point does not change.
The drawback was that combustion could not be detected at low temperatures, resulting in ignition failure.

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 reduce excess air at low temperatures to prevent ignition failures from occurring.

Structure of the Invention In order to achieve the above object, the present invention has a structure in which the rotation speed of the burner motor is changed to eliminate the influence of ambient temperature.

DESCRIPTION OF EMBODIMENTS One embodiment will be described below with reference to FIGS. 5, 6, and 7. First, FIG. 5 shows its control circuit, and a is exactly the same as the circuit of the conventional example, except that the burner motor 18 portion is replaced by a burner motor circuit 18'. This burner motor circuit 18' will be explained in detail with reference to FIG.
In FIG. 5b, this circuit 18' is connected to the AC power supply 1
A closed loop is formed from point 3' to point j, burner motor 18, and diode bridge 31. Positive side k point of diode bridge 31 - thyristor 32 -
A closed loop is also formed with the negative side l point of the bridge 31. From point j, diode 33-resistance 34-m
A point-zener diode 35-l is connected to the point. A smoothing capacitor 36, a light emitting diode 38 of a photointerrupter 37, a protective resistor 39, and a resistor 40-n point-phototransistor 41 are connected to the Zener diode 35 in parallel. From point n, capacitor 42 - point o - diode 43 (cathode on point o side) is connected to point l, diode 44 of the anode on point o side - point p - capacitor 45 is connected to point l,
Thermistor 46 and resistor 47, resistor 4 between p and l points
8-Connect the circuit of point r and resistor 49 to point l. k
From the point is resistance 50 - s point - Zener diode 51
to point L, point s - resistor 52 - point t - capacitor 5
3 is connected to point l, and the diode 54 of the cathode on the point s-point s side is connected to point t. Further, the output point u of the operational amplifier 55 having positive and negative inputs at points t and r is connected to the gate point v of the thyristor 32 via a resistor 56 .
Note that a resistor 57 is connected between points v and l.

FIG. 6 shows the burner motor 18, and the shaft 5
A circular plate 58 is attached to 7, and a circular hole 59 is provided around the entire circumference of the circular plate 58, and a photointerrupter 37 is attached so that light passes through this circular hole.

Next, this circuit will be explained. When the relay contact 17 is closed under the control of the control circuit 22, a voltage is generated in the AC power source 13' in FIG. 5b. The AC voltage is from point j to burner motor 18 to bridge k.
The closed loop of point-thyristor 32-point-l-point-w allows the burner motor 18 to be energized only when the thyristor 32 is conductive. Whether this energization is performed or not depends on whether a voltage is applied to the gate v of the thyristor 32.

Now, a DC voltage is generated between the points ml by the diode 33, the resistor 34, the zener diode 35, and the capacitor 36. Further, although the light emitting diode 38 is always lit, light with a frequency proportional to the rotation speed enters the phototransistor 41 due to the circular hole plate 58, so that point n is ON-
CFF is repeated. As a result, when the n point of the capacitor 42, which has a relatively small capacitance, is high, a current sufficient to fill the capacitance of the capacitor 42 flows through the circuit of the resistor 40 - capacitor 42 - diode 44 - capacitor 45, and the capacitor 45 is charged with this current. . When n point is low, phototransistor 4
The battery is discharged in the 1-diode 43 circuit, and the same charging current flows again during the next charging. In this way, a circuit is formed in which the charging current determined by the capacitor 42 and the resistor 40 is integrated into the capacitor 45. When the charging voltage at point p reaches a certain value, the combined resistance value of resistors 48, 49, 47 and thermistor 46 causes discharging, and therefore the voltage at point p is determined in proportion to the rotational speed of the motor. Ru. Next, the operation of the thyristor 32 will be explained using FIG. 7. First, FIG. 7a is a diagram before the thyristor 32 between points k and l becomes conductive, and a DC full-wave voltage is generated and applied between the anode and cathode of the thyristor 32. In addition, the s point has a nearly rectangular wave b due to the zener diode 51 and the resistor 50.
During this half cycle, due to the resistance 52 and the capacitor 53, at point t, the charging waveform of the capacitor 53 appears as is, as shown in c. (It is discharged every half cycle by the diode 54.) Next, as described above, the voltage at point r is determined by the temperature and the rotation speed of the motor 18, and forms a straight line _r0 as shown in d. Diagram d is drawn together with diagram c. Here, at the intersection t ₀ of the charging waveform t characteristic of the capacitor 53 and the reference voltage r ₀ , the output point u of the operational amplifier 55 becomes high, and the thyristor 32 becomes conductive. The solid line in Figure e shows this state, and at the burner motor 18, where the quarter shape is the burner motor 18, it becomes an alternating current waveform as shown by the solid line in Figure F.

Assuming that the temperature decreases, the resistance value of the thermistor 46 increases, and as a result, the voltage at point p increases and becomes r ₀ → r ₁ in FIG. 7d, then the intersection point t ₀
elongates to _t1 , so that the waveform at e becomes like the dashed line, and the waveform applied to the burner motor at f also becomes like the dashed line. Therefore, the rotation of the motor 18 decreases. That is, the thermistor 46
The rotation speed of the burner motor 18 is determined by the resistance value of the burner motor 18.

By the way, although it is not directly related to the purpose of this time,
Since a feedback circuit is used in this way, if we consider the case where the voltage suddenly rises, the rotational speed will rise, the number of pulses will increase, and the charging voltage of the capacitor 45 will rise, but the constant of p ( Since the resistance (resistance value and capacitor capacity) are constant, the conduction angle of the thyristor 32 becomes smaller accordingly, and the rotation speed eventually becomes constant. Since the rotation speed is determined by the constant of p in this way, it is also effective against voltage fluctuations and frequency fluctuations.

Effects of the Invention As is clear from the above description of the embodiments, according to the present invention, when the temperature changes, the rotation speed changes accordingly, so combustion can always be maintained in a stable state, and ignition failures and mistakes can be prevented. can do.

Further, since the present invention uses a feedback circuit, it is effective against voltage fluctuations and frequency fluctuations, and has the advantage that a damper for frequency switching is not required.

[Brief explanation of drawings]

Figure 1 is a sectional view showing a conventional fan heater, Figure 2 is a structural diagram of its burner, Figure 3 is its circuit diagram,
FIG. 4 is an explanatory diagram of the operating voltage. Figure 5a,
b is a circuit diagram of an oil combustor in one embodiment of the present invention, FIG. 6 is an explanatory diagram showing a method of detecting the rotational speed of the same motor, and FIG. 7 is an explanatory diagram of the same operation. 4...burner, 12...flame rod, 28
... Resistor, 29 ... Capacitor, 18 ... Burner motor, 58 ... Disc, 37 ... Auto interrupter, 46 ... Thermistor.

Claims (1)

[Claims] 1. A burner that vaporizes and burns kerosene, a flame rod, and a control circuit that applies an alternating current voltage to the burner and the flame rod and detects the combustion state using a rectification phenomenon of the current flowing from the flame rod into the flame. means for converting the rotation speed of a motor that sends combustion air to the burner into a voltage, the voltage obtained by the voltage conversion means is changed by a room temperature detection element, and this voltage is used to control the rotation speed of the motor. An oil combustor characterized in that the flame rod current is controlled by: