JPS6346270B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a slow start circuit for a water heater using an electromagnetic pump.

In a water heater that uses an electromagnetic pump to spray kerosene and ignite it to heat the water inside the case, if the kerosene discharge pressure is, for example, approximately 7 kg/cm ² during normal combustion, it will make a fairly loud noise when ignited. Therefore, there is a problem that the impact on the environment is large. The purpose of the present invention is to reduce such ignition noise and reduce the impact on the environment.

FIG. 1 shows a conventional example. That is, the power supply 1 forms a closed loop with the switch 2, the electromagnetic pump 3, and the thyristor 4, and the gate circuit 5 of the thyristor 4 has a conduction angle of the load that is initially small, but increases after a while until the load reaches its maximum. It's starting to work.

In this operation, the thyristor 4 is made conductive by a signal determined by the gate circuit 5 and a voltage is applied to the electromagnetic pump 3 to operate.
The gate signal of the thyristor 4, which is determined by , has a small conduction angle. After a while, the conduction angle increases and the thyristor 4 becomes almost fully conductive.
In this way, initially, the discharge pressure of the electromagnetic pump 3 is low, but after a few seconds, the discharge output becomes normal, and normal combustion occurs. In this way, since the discharge pressure is low especially during ignition, the ignition noise is low and the purpose is achieved. A disadvantage of this is that the thyristor 4 generates noise, which affects radio and television.

The present invention improves these drawbacks and enhances the slow start effect.

FIG. 2 shows the configuration of an embodiment of the present invention. That is, a power source 1 and a switch 2, a diode 3 having an anode on the switch 2 side, an electromagnetic pump 4 at a point a with its cathode side, and an electromagnetic pump 4 and a power source 1 are connected at a point b to form a closed loop. Further, a series circuit including a relay contact 5 and a capacitor 6 is connected to both ends of the diode 3.
In addition, a series circuit is constructed such that it goes from point a to point b, and the diode 7 with the point a side as the anode → the resistor 8 → the point c and the zener diode 9 with the cathode on the side of c → the point b, and the power supply of the timer circuit. make. In this case, a capacitor 10 is connected to both ends of the Zener diode 9 to smooth the waveform. A timer circuit is configured between points c and b. That is, series circuits of resistor 11 and capacitor 12 and resistor 13 and resistor 14 are connected from the point c side, and the connection points of these series circuits are designated as d and e.

In addition, a transistor 17 is connected to the input side of the differential amplifier 15 from points d and e, and a transistor 17 is connected to the output side through a resistor 16.
connected to the base of The emitter of the transistor 17 is connected to point c, and the collector is connected to point b through the relay coil 18 of the relay contact 5.

FIG. 3 is a diagram for explaining the operation, and the operation of this circuit will be explained. Needless to say, the AC voltage supplied from the power source 1 has a waveform with equal positive and negative values as shown in a of FIG. When the switch 2 is closed, the relay contact 5 is closed, so that voltage is applied to the electromagnetic pump 4 through the diode 3 and the series circuit of the relay contact 5 of the relay 18 and the capacitor 6.
That is, the first time when the diode 3 side is positive, the voltage waveform applied to the electromagnetic pump 4 is the same as that of the diode 3.
Since there is only 1 voltage, the waveform is exactly the same as that of the power supply 1 voltage, which is shown in FIG. 3b-1.

Next, when the side of point b becomes +, power supply 1 → b
Point → Electromagnetic pump 4 → Point a → Capacitor 6 → Relay contact 5 of relay coil 18 → Switch 2 → Power supply 1
Since a current flows through the circuit, a charging current flows through the capacitor 6. In this case, if the capacity is set so that charging is sufficient within the half cycle, the third
The voltage waveform shown in Figure b-2 is the electromagnetic pump 4.
is applied to That is, at first, a large amount of charging current flows, but as charging is completed, the voltage applied to the electromagnetic pump 4 becomes lower, and the discharge of the capacitor 6 ends when the voltage of the power supply 1 becomes 0.

If the diode 3 side becomes positive in this state, the waveform becomes exactly the same as the power supply 1 voltage as shown in FIG. 3b-3.

When such a cycle is repeated, the resulting waveform will look like the thick line waveform in b-4 in Figure 3.
In this case, although the waveform is partially distorted, if the relay contact 5 is closed, the waveform becomes a waveform that includes an alternating current component.

Next, the DC voltage generated across the Zener diode 9 applies voltage to the circuit of point c → resistor 11 → point d → capacitor 12 and the circuit of point c → resistor 13 → point e → resistor 14, so that A reference voltage is set at point e, and point d is 0V immediately after switch 2 is turned on because there is no charge in the capacitor 12, but as the charge gradually accumulates, the potential at point d rises and reaches point e in a few seconds. is equal to The output of the differential amplifier 15 is in the OFF state when the point d is lower than the point e, and since the base potential of the transistor 17 is equal to the point c, the transistor 17 is in the OFF state, so the relay coil 18 is de-energized. and closes relay contact 5.

Now, when point e and point d are equal, differential amplifier 1
5 has the same potential as point b, the transistor 17 is turned on, the relay coil 18 is energized, and the relay contact 5 is opened.

When the switch 2 is closed in this manner, the relay contact 5 is initially closed, but is opened after a few seconds. In the case of this open circuit, the voltage applied to the electromagnetic pump 4 becomes a half wave as shown in FIG. 3c.

Initially, a modified AC waveform as shown by the thick line in FIG. 3b-4 is applied to the electromagnetic pump 4, and after a few seconds, a complete half wave is applied.

Generally, when an AC waveform itself is applied to the electromagnetic pump 4, the plunger cannot follow it and it does not operate normally, but when the voltage waveform is low on the negative side as shown in Figure 3, the operation of the electromagnetic pump 4 is restricted, and the discharge is reduced by that amount. Output can be lowered. Next, after several seconds have passed, the relay contact 5 is opened, resulting in a half wave, and the electromagnetic pump 4 operates normally and the discharge pressure becomes appropriate, resulting in normal combustion.

As described above, according to the present invention, in a water heater using an electromagnetic pump that operates at an AC half wave using a diode, a capacitor is connected in parallel to the diode, and initially the electromagnetic pump is operated at an AC half wave using a diode and a capacitor. A timer circuit is used to open the capacitor after a while after the switch is turned on, and only the AC half-wave generated by the diode is applied to the electromagnetic pump. Initially, the discharge pressure of the electromagnetic pump is low, and after a while, the discharge pressure reaches the normal level, allowing normal combustion to occur.This makes it possible to reduce the ignition noise, and as a result, this capacitor Unlike thyristors, etc., it does not generate noise, and unlike methods that limit the operation of electromagnetic pumps with resistors, it does not cause temperature rise.
Moreover, due to the action of the capacitor connected in parallel to the diode, the voltage applied to the electromagnetic pump is a half-wave voltage from the initial state, so the diode type electromagnetic pump can be operated reliably. This makes it possible to obtain something that is very easy to use.

In addition, the pressure fluctuation of the electromagnetic pump during ignition due to the power supply voltage changes in proportion to the capacitor, making it easy to design.

However, the drawback is that the capacitance of the capacitor does not necessarily match the value determined by JIS, so it is necessary to use a capacitor with a special capacity.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a conventional example, FIG. 2 is a circuit diagram showing an embodiment of the present invention, and FIG. 3 is a voltage waveform diagram explaining the same operation. 1...Power source, 4...Electromagnetic pump, 5...Relay contact, 6...Capacitor, 15...Differential amplifier.

Claims (1)

[Claims] 1. In a water heater using an electromagnetic pump operated by a diode in an AC half-wave, a capacitor is connected in parallel to the diode, and the capacitance is set so that the capacitor is charged within a half-cycle of the AC. A composite voltage of the AC half-wave generated by the diode and the AC flowing through the capacitor is applied to the electromagnetic pump, and after a while after the switch is turned on, the capacitor is opened using a timer circuit, and only the AC half-wave generated by the diode is applied to the electromagnetic pump. A slow start circuit characterized by: