JPS6011784B2 - hot water machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water heater having both a key body corrosion prevention function and a dry heating prevention function.

In water heaters, it is well known to protect the foundation from corrosion and to automatically prevent dry firing. Initially, the hair body was used as a negative electrode and the anti-corrosion electrode was used as a positive electrode, and a voltage of several volts was applied between the two. A so-called anti-corrosion circuit that protects the key body from corrosion by applying the same amount of water and, for example, a plurality of thermistors etc. attached to the key body in the vertical direction, detects the water level in the bonito fish body, and if the water level is lower than a predetermined water level, it will notify that fact. The so-called dry-burn prevention circuits that display the display and stop the heating of water or hot water are electrically completely independent from each other, and recently attempts have been made to improve these circuits, and corrosion-preventing electrodes and At present, corrosion-proofing and dry-firing prevention circuits with single electrodes and common circuits that share the same electrode as the dry-firing detection electrode have been proposed. A schematic diagram of this corrosion protection and dry firing prevention circuit will be explained with reference to FIG. That is, in FIG. 1, 1' is the hammer body of the water heater, which is grounded.

Reference numeral 2 denotes a fin device which is electrically insulated from the traditional body 1 and disposed within the support body 1, and serves as both a corrosion protection electrode and a water level detection electrode, as will be described later.

3 is a corrosion protection power supply consisting of a constant voltage circuit, which not only outputs a corrosion protection voltage but also has a relay circuit for detecting the water level and turning ON/OFF the contacts.

4 is a rectifier circuit having a step-down transformer; 5 is a combustion control circuit for controlling the supply of fuel to the combustor (not shown) based on the combustion command; ignition control for sending combustion air to the combustor;
Control to perform pre-purge, control to perform post-purge, control to stop fuel supply and air blowing to the combustor in the event of abnormal combustion or ignition failure, control to supply water or hot water to the combustor in response to the output of the dry firing prevention circuit. It performs various controls required for a water heater that uses a combustor as a heat source, such as control to stop combustion for heating.

6 is a blower that supplies combustion air to the combustor; 7 is a manual power switch that is also a contact point for controlling the blower 6, and is opened and closed based on various controls by the combustion control circuit 5, supplying combustion air to the combustor. If there is a need to supply it, it is opened; otherwise, it is left open.

9 is a commercial AC power source.

The one in Figure 1 has the above configuration, with an electrode 2 and an ant body 1.
Corrosion protection of the barbel body 1 is carried out by the corrosion protection voltage of several V applied between the fin body 1 and the water level in the fin body 1 becomes lower than the electrode 2 ~ A current (corrosion protection current) flows from the electrode 2 to the fin body turtle. When it runs out, the IJ relay circuit in the corrosion protection power supply 3 is activated, and the combustion control circuit 5 is activated based on the operation of this relay circuit, and the fuel supply to the combustion machine is stopped and the contact point is opened and the blower is turned on. 6 stops and combustion stops.

Furthermore, if the water level in the cage 1 is lower than the electrode 2 at the time of starting combustion, combustion will not start. That is, dry firing prevention is performed. As is clear from the above explanation, the one in Fig. 1 has a water level judgment based on water level detection (whether it is below the set water level or below) in the corrosion protection electrode 3, which was originally provided for corrosion protection. Since the configuration is such that a relay circuit is provided to carry out the judgment (judgment of It is about several volts and several hundred MA.
Therefore, in the conventional circuit shown in the diagram shown in the diagram, which uses the electrode 2 in common to detect the water level and prevent dry firing using the anti-corrosion current, the structure is such that the water level is detected using the anti-corrosion current.
The voltage for water level detection is low and the current is also small, making it difficult to reliably detect the water level. In particular, in water heaters, the water resistance changes depending on the quality and temperature of the water supplied to the unit 1, so it is necessary to take this change in resistance into consideration in order to fully demonstrate the dry heating prevention function. is quite difficult.

The inventor considered the circuit configuration shown in FIG. 2 as a configuration to eliminate the drawbacks of the conventional circuit shown in FIG.

That is, in Fig. 2, turtle 8' is a water level detection electrode that is electrically insulated from the scale turtle by the insulator Kamegawa, and its tip protrudes into the body of the bonito.

The oven 3 is a dry-firing detection circuit that applies a voltage to the water level detection electrode 81 and detects whether the water level in the bonito body 1 is above a predetermined water level, and supplies the output to the combustion control circuit 5. Turtle 4! Also, there is an insulator that electrically insulates the corrosion protection electrode 2 and the hair body 1. Tomi 5 is an oil-burning combustion machine, for example. Turtle 6 is a supply that supplies water to the inside of the bonito body turtle. The hole 7 is the water surface of the wound outlet t18 for taking out the hot water in the fabric volume.Next, the operation of the embodiment shown in FIG. 2 will be explained.

First, with the water level gate 8 in the position indicated by the solid line, turn on the power switch 7 and operate the operation switch (not shown) of the combustion engine frame 5 to start combustion. At this time, the dry firing detection circuit 13 detects that the water level in the bell body 1 is above a predetermined level and supplies the signal to the combustion control circuit 5, so the combustion control circuit determines that it is OK to start combustion and closes the contact. After the blower 6 rotates and the inside of the combustor 15 is pre-purged, fuel is started to be supplied to the combustor and ignited to start combustion, and the water in the fin body 1 is heated. .When the water in the bonito body rises to a specified temperature,
A temperature sensor (not shown) is activated, and its output is supplied to the combustion control circuit 5 ~ The fuel supply to the combustion machine 15 is stopped, and after this stop, the contact 8 is opened after a predetermined period of time, and the post purge is completed. do. On the other hand, when the hot water in the bonito body 1 is used during combustion and the water level 18 falls to the level indicated by the - dotted chain line, "In other words, when the water level falls below the level of the water level detection electrode 0, hot water flows from the water level detection electrode 10 to the key body. 1 stops flowing, the dry firing detection circuit quantity 3 detects that the water level has fallen below a predetermined level, and its output is transmitted to the combustion control circuit 5, After that, the contact 88 is opened after a predetermined period of time, and the post-purge is completed.It goes without saying that the supply of water into the fuselage 1 is automatically performed by conventionally known means.Corrosion prevention This is done using the corrosion protection electrode 2.

As is clear from the figure, the corrosion protection electrode 2 is provided below the water level detection electrode, so even if the water level falls to a level that requires dry firing prevention, corrosion protection is independent of the dry firing detection. Continue corrosion protection operation. As is clear from the detailed explanation above, the one in FIG. 2 has a circuit configuration in which the dry firing detection circuit 13 does not become a load on the corrosion protection power supply 3, so the corrosion protection power supply 3 fully exhibits its corrosion protection function. In other words, water quality fluctuations,
Taking water temperature fluctuations into consideration, the corrosion protection function can be maintained even if there is a considerable fluctuation, and the dry firing detection circuit color 3 can also be set to the water level detection electrode 1 without considering the effect on the corrosion protection function.
The circuit configuration shown in Figure 2 has an alternating current component for water level detection added to the direct current corrosion-proofing potential. The voltage between the ground and point C will be as shown in Figure 3.Therefore, it will be necessary to adjust the DC and AC components, and if this adjustment is not done properly, the diagonal line in Figure 3 will appear. A potential is generated that promotes silkworm feeding.Also, since alternating current is superimposed on direct current, it is difficult to set the corrosion-proofing potential within the theoretical optimum range. The purpose of this is to supply sufficient power to the dry firing detection circuit to ensure its operation, and to fully demonstrate its corrosion prevention function.

An embodiment of the present invention will be described below with reference to FIGS. 4 and 5. That is, in FIGS. 4 and 5, 10a9
The turtle ob is an electrode for water level detection that is electrically insulated from each other.
19 is an electrode 18a for water level detection, an electrode 2 for corrosion protection, an insulator for electrically insulating between the whiskers, 20 is an adjacent voltage circuit consisting of a transformer, 201 is a primary winding of the step-down circuit 2Q, 282 Vines? 2822 is the secondary winding of the step-down circuit 20, 21' is a diode bridge, 22 and 23 are capacitors, 24 is a resistor, and 25 is a constant voltage diode.
7 is a diode, 28 and 29 are resistors, and 30 is a light emitting diode, which are optically coupled to a phototransistor (not shown) connected in series with various safety circuits in the combustion control circuit 5.

31' is a Darrington-connected transistor, and 32 is a capacitor.

Next, the operation of the one shown in FIG. 5 will be explained.

First, to explain the corrosion-resistant circuit, “Secondary winding 2021
The output is full-wave rectified by a diode bridge 21, and the resulting DC is smoothed by a capacitor 22.

The charging voltage of the capacitor 23 is determined by the constant voltage diode 2.
A constant voltage is applied to the electrode 2 via the electrode 5 to provide the desired corrosion protection. A voltage shown in FIG. 6A appears between this electrode 2 and the ground. Next, to explain the water level detection circuit, a half-wave of one polarity of the output of the secondary winding 2022 flows as shown by a solid line, and a half-wave of the other polarity flows as shown by a dotted line. A voltage shown in Figure 6 appears between them.Since the light emitting diode 30 emits light when the current flows as shown by the solid line, a phototransistor (not shown in the figure) optically coupled to the light emitting diode 30 emits light. (Although not provided in the combustion control circuit 5),
A signal indicating that current is flowing between the electrodes IQa and 10b, that is, that the electrodes oa and 10b are short-circuited by water, is transmitted to the combustion control circuit 51. When the water level drops and the water no longer shorts the electrodes 10a and 18b, the light emitting diode 38
Since no current flows and no light is emitted, similarly to the above, the fact that the water level has fallen below a predetermined level is transmitted to the combustion control circuit 5 as a signal. The water level inside the key body car is detected, and the control by the combustion control circuit 5 based on this detection is the same as that shown in FIG. 2, so a description thereof will be omitted. As is clear from the above explanation, in the present invention, since the alternating current for water level detection flows between the pair of electrodes 18a and iob for water level detection, the voltage between the whisker body ground and point C is There is no possibility that a haze voltage like that shown in FIG. 2 will appear, and the haze voltage can be easily set within the theoretical optimum range without being affected by alternating current.

In addition, the water level detection circuit also has a secondary winding 202 separate from the corrosion protection circuit.
Since the power source is taken from 2, sufficient power can be applied without being affected by the corrosion protection circuit, and the detection operation is performed reliably. Brief explanation of the drawings Figure 1 is a schematic diagram of a conventional water heater, Figure 2 is a schematic diagram showing an improvement plan for the conventional one, and Figure 3 is a diagram of the water heater and predetermined points in the one shown in Figure 2. (point C), FIG. 4 is a schematic diagram showing an embodiment of the present invention, and FIG. 5 is a diagram showing the voltage between
Detailed connection diagram of the main parts of the figure ``Figure 6 is a diagram showing the voltage of each part of the figure 5. A is the tortoise pressure between the corrosion protection voltage and the ground, and the opening is the voltage between the water level detection electrodes. , C are diagrams showing the voltages between the clay earth and a predetermined point (point C), respectively.

In the figure, 1 is the whole, 16 is the combustion machine, 5 is the control circuit,
2 is an electrode for corrosion protection, 3 is a power source for corrosion protection, 10a. 10b is a water level detection electrode, and 13 is an empty firing detection circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts. Figure 1 Key Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Scope of Claims] 1. A control circuit that controls fuel supply to a combustor that heats water in the casing and a blower that supplies combustion air to the combustor, and a power supply system for corrosion protection and water level detection. A voltage step-down circuit separate from the above, a corrosion-proof electrode provided in the case so as to be electrically insulated from the case, and a corrosion-proof electrode provided between the corrosion-proof electrode and the case; a corrosion protection circuit that protects the casing by applying a DC voltage from a corrosion protection power supply system of the step-down circuit so that the voltage is at a low potential; At the same time, a pair of water level detection electrodes to which an alternating current voltage is applied from the water level detection power supply system of the step-down circuit, and a determination is made as to whether or not there is continuity between the water level detection electrodes due to water in the casing, and the water level in the casing is set to a predetermined value. A water heater characterized by comprising an empty firing detection circuit that stops combustion for heating the combustor in the following cases. 2. The water heater according to claim 1, wherein the electrodes are insulated from each other by a common insulator and from the casing by the insulator. 3. The water heater according to claim 1 or 2, wherein the water level detection electrode is horizontally disposed at a higher position than the corrosion protection electrode within the casing. 4. The water heater according to claim 1, wherein the step-down circuit is constituted by a transformer including a primary winding and a pair of secondary windings.