JPS5947820B2 - water heater display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a hot water supply system having a hot water temperature control device that detects the temperature of hot water supplied from a heat exchanger and controls the combustion amount of a burner to maintain the hot water supply temperature at an arbitrarily set temperature. Regarding boilers, especially instantaneous gas water heaters, a circuit should be installed to indicate when the hot water supply load exceeds the water heater's maximum capacity or minimum combustion rate, or if the water heater becomes uncontrollable. This is what I did.

Burning amount The temperature of water in a water heater is determined by the formula □10 water temperature.

The amount of hot water supplied and the maximum amount of combustion in a water heater is determined by the burner, and at the same time, the minimum amount of combustion to ensure stable combustion is also determined.

To explain in more detail with reference to Figure 1, A is the maximum combustion amount curve, B is the minimum combustion amount curve, the horizontal axis Q is the hot water supply flow rate, and the vertical axis T is the hot water temperature rise (hot water temperature - water supply temperature). show.

In the part narrowed by AB in the figure, that is, in the control range, it is possible to obtain a constant set temperature T even if there is a change in the flow rate by increasing or decreasing the combustion amount using, for example, a fuel proportional control valve.

However, for example, when hot water is being supplied at a temperature T1 with a hot water supply amount Q1, if the flow rate is throttled to Q2, the hot water goes out of the control range and enters the lowest combustion range, and the hot water temperature rises to T2, posing a risk of burns.

On the other hand, if it increases to Q3, the maximum combustion amount will be reached and the water temperature will be T.
It drops to 3.

The present invention has focused on the above-mentioned problems, and provides a display to inform the user when the water heater is out of the control range.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a circuit diagram of an embodiment of the present invention.

A combustion proportional solenoid valve is used here.

Reference numeral 1 denotes a DC power supply, which is energized to the control circuit by a switch 2 that is automatically turned on when water supply starts.

3 is a hot water temperature detector, in which a negative characteristic temperature-sensitive resistance element (hereinafter referred to as a sensor) was used.

The sensor 3 and resistors 4, 5, and 6 form a bridge circuit I, and the control circuit (2) compares the potential CD with an operational amplifier 7 (hereinafter referred to as an operational amplifier), inverts and amplifies it, and divides it with resistors 8 and 9. The transistor 10 is driven by the generated potential, and the current of the proportional valve coil 11 is controlled.

The gain of the operational amplifier 7 is determined by R13/R12.

Further, the capacitor 14 is an integrating capacitor, and is charged when the CD point becomes unbalanced to increase or decrease the current in the coil 11 and control it so that C=D.

Figure 3 shows this characteristic, where the horizontal axis shows time t, the vertical axis shows the coil current ■ and the difference E between potentials C and D, and shows the transient characteristics when the hot water supply amount is changed at time t'. .

As mentioned earlier, the control area is shown in Figure 3.

Here, we show the case where the flow rate is changed from Ql to Q4,
As the flow rate increases, the hot water supply temperature decreases, so the resistance of the sensor 3 increases and the potential C also decreases.

Therefore, the base potential of the transistor 10 increases, the current in the coil 11 increases, and the amount of combustion increases.

This increases the temperature of the water and lowers the resistance of the sensor 3.
The potential C is increased, but if C=D does not hold due to drooping characteristics or the like, it is corrected by the integrating capacitor 14 to prevent an increase in the current (2) at the point where C=D.

However, as in the case of Figure 3a, the flow rate increases from Q to Q3.
When the current I increases, the current I continues to increase, but does not exceed the capacity A, so the temperature falls on the curve A.

In this case, C=D will never hold.

Therefore, when C and D are compared by the comparator 12 of the comparator circuit (■) in FIG. Then, the light emitting diode (hereinafter referred to as LED) 16 is turned on.

When the potential C=D, the resistors 17 and 1B make the positive input terminal of the comparator 12 lower than the negative input terminal to make the output zero.

In this way, when the potential C<D as shown in FIG. 3a, that is, when the water heater becomes uncontrollable due to the maximum capacity curve A, the LEDI 6 lights up to display this.

Note that 17 is a current limiting resistor of the LEDI 6, 18 is an emitter resistor of the transistor 10, and 19 is a diode for absorbing back electromotive force of the coil 11.

FIG. 4 shows another embodiment.

Components with the same functions as those in FIG. 2 are given the same numbers, and their explanations will be omitted.

In the circuit shown in FIG. 2, the LED 16 indicates the maximum capacity, but the circuit shown in FIG. 4 allows the display to be displayed even during the minimum combustion.

In other words, when the flow rate changes from Q1 to Q2 as shown in C in FIG. 3, even if the current I decreases to zero, the minimum combustion amount is ensured, so the potential C>D continues forever.

In this case, the water temperature rises above the set temperature, posing the risk of burns, etc., when using the shower, for example.

Therefore, in FIG. 4, a comparator 20 is provided with the potential CD connected to the opposite input to the comparator 12, so that the potential C>
Output when D.

Also, a diode 212 is connected to the output terminal of the comparator 12.20.
2 are connected to each other, and the cathode of the diode 2122 is connected to the resistor 13.

As described above, an OR circuit (2) is constructed in which the LED I 6 lights up even when either of the comparators 12 and 13 outputs an output.

The resistors 23 and 24 are used to apply the divided potential to the positive input of the comparator 20 and to make the output zero when the potential C=D.

FIG. 5 shows yet another embodiment.

In the circuit of FIG. 4, the comparators 12 and 20 have a potential C\0
In this case, one of the two is always output, and the LED
16 is lit.

In other words, as shown in FIG. 3, even if the flow rate is within the control range, the potential temporarily becomes C\D when the flow rate changes, so the LBD 16 is lit during this time.

If you are using a shower or the like, you can rest assured that while this LED is lit, it will indicate that the temperature has deviated from the set temperature for some reason.

However, in this case, it is difficult to distinguish from the capacity state, so in FIG. 5, the LED 16 is turned on only when the potential C\D is maintained for a certain period of time by the timer circuit (2).

In FIG. 5, when the output of the OR circuit of diodes 21 and 22 occurs, the capacitor 26 is connected through the resistor 25.
When charging begins and the potential at the positive input terminal of the comparator 27 gradually increases and exceeds the potential F, the LED 16 output from the comparator 27 lights up.

Now, in the case shown in Fig. 3, the OR input is output and before the charged charge reaches F, the potential returns to C=D, and the OR output disappears.

Therefore, the charge is discharged through the diode 28 and the resistor 29, and the LED 16 does not light up.

In other words, only when the potential C\D continues for longer than the timer operation time, the LED 16 lights up to indicate that control is not possible.

As explained above, according to the present invention, the maximum of the water heater,
This message is displayed when the fuel is out of control due to the minimum combustion amount, so users can use it with peace of mind.

It is especially effective when using the shower. In addition, since the detection signal is detected from the bridge circuit that includes the sensor, it can be displayed regardless of the type or pressure of the fuel gas.It is highly accurate and has little variation, and the light emitting element will not light up even if the sensor is in the oven or short-circuited. Highly safe.

[Brief explanation of the drawing]

Fig. 1 is a water temperature control characteristic diagram of a water heater, Fig. 2 is a diagram showing a control circuit in an embodiment of the present invention, Fig. 3 is a diagram showing transient characteristics when the flow rate changes, and Fig. 4 is a diagram showing other characteristics. FIG. 5 is a diagram showing a control circuit in another embodiment. FIG. 5 is a diagram showing a control circuit in yet another embodiment. 3... Hot water temperature detector, 7... Operational amplifier, 11... Coil of electromagnetic proportional control valve (combustion amount controller), 16... Light emitting diode (display circuit), ■...Bridge circuit, ■...Control circuit, ■...Comparison circuit, ■'...OR
Circuit,■・・・・・・Timer circuit.

Claims (1)

[Scope of Claims] 1. A combustion amount controller that varies the combustion amount of a burner, a hot water temperature detector that detects the temperature of water heated by the burner, and a bridge circuit that includes the hot water temperature sensor on one side; a control circuit that amplifies the potential at the midpoint of the bridge circuit and outputs a signal No. 1 that drives the combustion controller so that the temperature of the hot water temperature sensor becomes a predetermined temperature; a comparison circuit that detects that the midpoint is unbalanced;
A display device for a water heater, comprising a display circuit that displays based on the output of the comparison circuit. 2. The water heater display device according to claim 1, wherein the display circuit includes an OR circuit that outputs an output even if the balance of the bridge circuit is shifted in either the positive or negative direction. 3. The water heater display device according to claim 1 or 2, wherein the display circuit includes a timer circuit that starts operation when the bridge circuit is out of balance and outputs a display output after a certain period of time. .