JPS5943685B2 - gas water heater - Google Patents

Description

Detailed Description of the Invention The present invention relates to a gas water heater that includes at least an all-primary air type gas burner and a heat exchanger in the main body, and is equipped with a mixing pipe, a zero governor, a fan motor for forced air supply and exhaust, etc. The aim is to keep it constant.

Conventionally, in gas water heaters, the gas flow rate is controlled by extracting the pressure difference generated at the nozzle in the mixing pipe according to the air supply amount using a zero governor, so the air supply amount and gas flow rate, the so-called excess air ratio, are kept constant. It was used as a thermal burnout control method suitable for all primary air type gas burners.

However, there is a combustion amount range in which the excess air ratio is kept constant, and there is a minimum combustion amount QBmin.

Therefore, if an air supply amount that is less than QBmin is given, the excess air ratio will exceed the appropriate value, leading to phenomena such as Reno 1 and bank combustion.

Also, the existence of QBmin means that if the product Q1 of the load, that is, the water temperature rise value and the flow rate, is smaller than the product η・Q of QBmin and the heat exchange efficiency η, then the expected temperature can be obtained as the min outlet temperature. The hot water temperature will be higher than that.

However, when the hot water outlet temperature is controlled, the user uses the hot water assuming that the hot water is at a predetermined temperature, which can lead to dangerous situations such as burns.

The present invention solves these conventional problems, and embodiments thereof will be described below with reference to the accompanying drawings.

In Fig. 1, a main body 1 includes an all-primary pneumatic gas burner 2, a mixing pipe 4 that mixes air supply and gas, and a pressure difference generated by a nozzle provided in this mixing pipe 4 according to the amount of air supply. A zero governor 3 and a heat exchanger γ are provided to control the opening degree of a tire phragm valve provided therein to control the gas flow rate.

The gas G passes through the zero governor 3 through the gas pipe, and the air passes through the air supply pipe 5 into the mixing pipe 4, where they are mixed and led to the burner 2.

On the other hand, water is introduced as W into the heat exchanger 7 through the water supply channel 6, and after heat exchange is supplied as H through the hot water outlet channel 8.

Exhaust gas is discharged through an exhaust path 9 and a fan motor 10.

In this example, a suction type supply/exhaust system is used, but this may be a push type or a push suction type, as long as it can perform forced supply/exhaust.

The rotational speed of this fan motor 100 is always controlled by a speed controller 11 whose output voltage is controlled according to the output of a temperature detection thermistor 12 provided in the hot water outlet path 8, and the fan motor 100 rotation speed is always controlled by a speed controller 11 whose output voltage is controlled according to the output of a temperature detection thermistor 12 provided in the hot water outlet path 8. For example, fan motor 1
Increase the 0 rotation speed to reduce the amount of combustion, and keep the hot water temperature constant without increasing it.

The rotation speed of the fan motor 10 is set in the speed controller 11.
A limiter is provided to regulate the minimum rotational speed so that the combustion amount does not fall below QBmin.

FIG. 2 shows an embodiment of the speed controller 11.

In the figure, 11A is a bridge circuit, with resistors AI, A2゜A
4 to form one side, and the other side to be formed by a thermistor 12 and a resistor A3 connected in parallel.

Resistor A3 is provided to improve the linearity of the thermistor 12.

11B is a differential amplifier 1J for amplifying the output of the bridge circuit 11A, and includes two transistors B1. B2.2
The bridge circuit 1 is formed by resistors B3 and B4.
1A and the amplifier 11B form a temperature detection circuit.

11D is a phase control circuit, which includes a transistor D1, a diode D2, a resistor D3, a capacitor D4, a resistor D5 . D7.
D8. It is formed by PUT B6, pulse transformer D9, and triac D10.

11E is a DC power supply circuit, in which the voltage of the commercial power supply 13 is snapped down by a transformer 11F is full-wave rectified by a diode bridge E1, and this voltage is clipped by a resistor E4 and a zener diode E5, and the full-wave rectifier is Voltage Vcc obtained by smoothing the voltage with diode E2 and capacitor E3
has an output of

11C is a limiter that sets the lower limit voltage when transmitting the output of the amplifier 11B to the phase control circuit, and the lower limit voltage is the zener diode C2 obtained by series connection of the resistor C1 and the zener diode C2. , and this voltage is transmitted to the phase control circuit 11D through the diode C4, and the output of the dJ amplifier 11B is transmitted through the diode C3.

If the output vB of the intensifier IJ 11B is lower than the zener voltage VZ, the input voltage of the phase control circuit 11D becomes the zener voltage, and if vB is lower than VZ,
The input voltage of the phase control circuit 11D is vB.

If the combustion amount reaches QBmin and the hot water temperature is still higher than the expected temperature, the resistance value of the thermistor 12 becomes /'', the output of the bridge circuit 11A decreases, and the output of the IJ unit 11B also decreases. Therefore, VB is lower than Vz.

Therefore, the voltage input to the phase control circuit 11D is VZ
Therefore, the capacitor D4 is initially charged with a voltage approximately equal to Vz.

The lower this initial charge value vc1, the lower the PUT
Since the time for the anode voltage vA of B6 to reach the gate voltage VG is delayed, the phase in which PUT B6 is turned on is delayed, the cross-contact angle of the triac D10 becomes small, and the rotation speed of the fan motor 100 becomes slow.

Since the lowest value of the input terminal of the phase control circuit 11D is VZ, the lowest rotational speed is determined by VZ.

Therefore, by selecting an appropriate value for VZ,
The minimum combustion amount Q can be ensured.

min FIG. 3 shows an embodiment of a voltage comparison circuit for lighting the light emitting diode L6 as an alarm device when vB becomes less than ■Z.

vB is applied to the negative input of voltage comparator L4 via resistor L1.

On the other hand, VZ is resistor L2. Appropriately divided by L3 and Vzt
The voltage is applied to the positive input terminal of the voltage comparator L4.

If VB is lower than Vzt, the output of voltage comparator L4 will be high and will be connected to light emitting diode L6 through resistor 5.
Current flows through the lamp and lights it up.

This allows the user to confirm that the load Q1 is smaller than QBmin, and therefore to recognize that the hot water will come out at a higher temperature than expected.

In other words, this voltage comparison circuit causes the light emitting diode L6 to change depending on the difference between the output voltage of the temperature detection circuit and the limiter output voltage.
is turned on and off to display the magnitude relationship between Ql and QBmin.

As described above, according to the present invention, the minimum combustion amount Q can be ensured simply by providing a limiter in the speed controller, so the combustion amount Q can be maintained regardless of the magnitude of the load Q1.
It never goes below Bmin (and stable combustion can always be achieved.

Furthermore, since the alarm device is turned on when Ql is smaller than QBmin, the user can recognize that the hot water is hotter than the expected temperature, and there is no risk of danger.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a gas water heater showing an embodiment of the present invention, FIG. 2 is a circuit diagram for controlling the water temperature, and FIG. 3 is a voltage comparison circuit diagram. 2... All primary air type gas burner, 3...
・Zero governor, 4...Mixing tube, 7...
Heat exchanger, 10...Fan motor, 11...
...Speed controller, 12...Temperature detector (thermistor).

Claims (1)

[Claims] 1. An all-primary air gas burner, a heat exchanger heated by the burner, a mixing pipe that mixes supply air and gas, and a zero governor that controls the gas flow rate according to the amount of supply air. It consists of a fan motor that forcibly performs air supply and exhaust, a temperature detector that detects the hot water temperature, and a speed controller that controls the speed of the fan motor according to the output of a temperature detection circuit including the temperature sensor, A gas water heater characterized in that the speed controller includes a limiter that regulates a minimum speed of the fan motor. 2. A patented gas water heater characterized by having an alarm device and a voltage comparison circuit that turns on and off the alarm device according to the difference between the output voltage of the temperature detection circuit and the limiter output voltage.