JPS6044564B2 - gas water heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a gas water heater that controls the flow rate of gas in accordance with the rotational speed of a forced air supply/exhaust fan motor to control the temperature of hot water.

BACKGROUND ART Conventionally, in this type of gas water heater, a zero governor is operated by extracting a pressure difference generated in a nozzle in a mixing pipe according to the amount of air supplied to control the gas flow rate.

According to the above means, the air supply amount and gas flow rate, so-called excess air ratio, are maintained at appropriate values, and the combustion amount of the water heater is controlled using a forced air supply and exhaust type and all primary air type gas burner. It was very useful for rate control. In order to control the outlet hot water temperature over a wide load range in such water heaters, it is essential to control the combustion amount over a wide range, and to do so, it is necessary to generate a relatively large pressure difference in the mixing pipe. . This leads to an increase in the size and weight of the fan motor, and also means an increase in fan noise, resulting in an unrealistic water heater. Problems to be Solved by the Invention The present invention achieves a wide range of combustion amount control, which has not been possible with the prior art, as described above, without increasing the size and weight of the fan motor.

Means for Solving the Problem In order to solve this problem, the present invention provides two gas burners.
A mixing pipe is installed in each burner, and a solenoid valve is installed to turn on and off the gas flowing into the mixing pipe on one side.When the load is large, this solenoid valve is turned on and both mixing pipes and It uses a burner and turns this solenoid valve on and off depending on the load.

The magnitude of the load is detected by the magnitude of the output of the hot water temperature detector. When the working load is large, the hot water temperature detector detects the temperature.The temperature will be lower than the set temperature, so when the hot water temperature is below the predetermined temperature, which is lower than the set temperature, the solenoid valve is turned on and both burners are burned.

Also, when the load is small, the hot water outlet temperature will be higher than the set temperature, so when the hot water outlet temperature is higher than the second predetermined temperature, which is higher than the set temperature, the solenoid valve is turned off and only one burner is operated. . Here, the combustion amount can be changed as follows by turning on and off the solenoid valve. Assume that the rotation speed of the fan motor is a certain rotation speed Nrpm. A pressure PaN corresponding to this rotational speed is generated in the mixing tube. The zero governor acts so that a gas pressure PgN corresponding to the pressure PaN on the air side in the mixing tube is generated in the gas in the mixing tube. If the zero governor is controlled by the pressure difference in the mixing pipe to which the solenoid valve is not connected, the gas pressure in the mixing pipe is determined according to the air pressure in the mixing pipe, that is, the rotation speed of the fan motor. If the rotation speed of the fan motor is constant, the gas pressure on the side to which the solenoid valve is not connected will be a pressure commensurate with the rotation speed, and the gas flow rate will be constant. On the other hand, the gas flow rate on the side to which the solenoid valve is connected is a gas flow rate commensurate with the rotational speed when the solenoid valve is on, but naturally becomes zero when the solenoid valve is off. That is, the gas flow rate flowing through the mixing pipe to which the solenoid valve is not connected is constant regardless of whether the solenoid valve is on or off. Therefore, the total gas flow rate changes depending on whether the solenoid valve is turned on or off. EXAMPLES Below, examples will be described with reference to the accompanying drawings.

In FIG. 1, a zero governor 2, a solenoid valve 3,
Two mixing tubes 4, 6, two all-primary air burners 5, 7
, a heat exchanger 11 are included. Gas G is zero governor 2
One of them passes through the solenoid valve 3 and reaches the first mixing pipe 4, where it is mixed with the air A1 supplied through the first air supply path 8 and sent to the first gas burner 5. reach. and - the other gas after separation reaches the second mixing tube 6;
mixed with air A2 supplied through the second air supply path 9;
The second burner 7 is reached. Water W is introduced into the heat exchanger 11 through the water supply channel 10, and after heat exchange, the water
It is served as a bath. The exhaust is the main body. 1 through an exhaust path 14 and a forced air supply/exhaust fan motor 13. The hot water temperature is detected by a temperature detector 15 installed in the hot water path,
The signal is input to the controller 16. The controller 16 includes a speed control circuit that controls the speed of the fan motor 13 according to the output of the temperature detector 15, and a control circuit that controls the solenoid valve 3 to turn on and off. FIG. 2 shows one embodiment of the controller 16.

A commercial power supply is connected to Ll, and D1 is a circuit for obtaining DC power from the commercial power supply.The voltage is obtained by step-down with a transformer and full-wave rectification with diode bridge D2. 1
, a voltage VD2 obtained through a filter of a diode D5 and a capacitor D6, and a voltage (2) obtained by clipping the above D1 with a resistor D3 and a zener diode D4.

16A is a bridge circuit, each side of which is formed by resistors Al, A2, A4, a thermistor 15'' as a temperature detector 15, and a resistor A3 connected in parallel thereto.

The parallel resistor JA3 is for the purpose of correcting the non-linearity of the thermistor 15''.The bridge output is connected to the transistor B.
Differential amplifier 16B composed of resistors B3 and B4
The output signal is inverted and amplified by the phase control circuit 16C and the comparison circuit 16E. The phase control circuit 16C includes resistors Cl, C4, transistor C2, emitter follower of diode C3, resistors C6, C8, C9, capacitor C5, PUTC7, pulse transformer ClO, triax Cll, and second A contact E6B of relay E6. Resistance E
It consists of an air amount increasing/decreasing means consisting of 8゛. If the input is large, the output voltage of the emitter follower is high and C
5, the initial charge value Vc, is high, and then the resistances C6 to E8
is charged by VDl, quickly reaches the divided voltage Vc of Vz of resistors C8 and C9, and PUTC7 is turned on with a fast phase.
This is a triax Cl through a pulse transformer ClO.
l is turned on, its conduction angle is increased, and the fan motor 13
Increase the rotation speed. Conversely, if the input voltage is small, the rotational speed of the fan motor 13 will be slow. When the tapped water temperature becomes higher than the set temperature, the resistance value of the thermistor 15 decreases, and the output of the bridge 16A increases, the output of the differential amplifier 16B decreases, and the input voltage to the phase control circuit 16 decreases. descend. Therefore, the rotational speed of the fan motor 15 decreases and the motor rotational speed becomes small, the amount of air supply is throttled, the gas flow rate is also throttled, and the amount of combustion is decreased, and the hot water outlet temperature is lowered and the set temperature is reduced. become. Differential amplifier 1
The output of 6B BO is input to the negative input terminal of the voltage comparator E4 via the resistor E1, and the resistor E input to the positive input terminal
The voltage VE2 is compared with a reference voltage E2 via the voltage VE2.
While ■BO is smaller than ■E2, the output of voltage comparator E4 becomes high, turning on transistor E7 and relay E6, and turning off electromagnetic valve 3 through contact E6A. In other words, when the load is large, the output temperature of the hot water becomes lower than the set temperature, and the output of the bridge 16A becomes small.
Since BO is large, the output of voltage comparator E4 becomes low, transistor E7 and relay E6 are turned off, solenoid valve 3 is turned on, and two burners 5 and 7 are burning. At the same time, E6B is off, so the gain of the phase control circuit is low. If the load decreases, the hot water temperature will become higher than the set temperature, and the combustion amount will become smaller. If the amount of air supply becomes less than the minimum pressure difference required by the zero governor 2, the excess air ratio control of the zero governor 2 will no longer work. In such a case, if the gas circuit on one side is shut off, the amount of combustion can be reduced to about 1/2 for the same amount of air supply.

Then, when the output of the bridge 16A becomes large and a small combustion amount is required, when the output of the bridge 16A becomes large and the output of the differential amplifier 16B becomes small, ■8. becomes smaller than E2, the output of voltage comparator E4 becomes high, transistor E7 turns on, relay E6 turns on, and the first B
Contact E6A is turned off, and solenoid valve 3 is turned off. At the same time, the first A contact E6B turns on, the gain of the phase control circuit 16C increases, and the amount of air supply increases. Here, the need to increase the amount of air supply is as follows. If the solenoid valve 3 is turned off while the air supply amount remains unchanged, the gas flow rate will decrease dramatically. In other words, QB is the minimum combustion amount of each burner for burners with the same combustion amount. l, then 2QBn. before turning off the solenoid valve 3. What used to be "in" will be halved to "QBmin". In order to change the combustion amount smoothly so that turning off the solenoid valve 3 does not have much effect on the combustion amount, it is necessary to switch the 2Q switch with two burners.
2 with one burner by turning off solenoid valve 3 from Bmin.
Q.B. ．． Since it is to move in, one burner can generate 2 QB. ．． In order to achieve this, it is necessary to increase the number of rotations and increase the air pressure in the mixing tube 6. Therefore, at the time of switching, it is necessary to increase the gain so that even with the same human voltage, a higher rotational speed can be obtained when the solenoid valve 3 is off than when it is on. However, since the solenoid valve 3 is off, the amount of combustion becomes 1/2 of the maximum. Therefore, for example, the on/off switching of the solenoid valve 3 can be controlled at 1 of the maximum combustion amount of the two burners.
/2 allows smooth switching. When the output of voltage comparator E4 becomes low, resistor E5 starts to enter, and its positive input terminal voltage increases the resistance values of resistors E3 and E5 by R3,
When R5 is set, it decreases to 1·■E2. Sunawa
R3+R5, hysteresis is created by resistors E3 and E5, in which the voltage at which the solenoid valve 3 turns on is different from the voltage at which it turns off.

This prevents the electromagnetic valve 3 from violently turning on and off when the load is approximately 1/2 in the above example. To summarize the present invention using the above example, the pressure difference generated in the mixing tubes 4 and 6 only needs to generate a pressure difference corresponding to 1/2 the gas flow rate when the TDR is taken to 1/4. . This is because the solenoid valve 3 is turned off when the amount is less than 1/2, so the combustion amount becomes 1/2 with the same intake air amount.
Further, the zero governor 2 only needs to respond to a pressure difference corresponding to 1/2 of the gas flow rate, and does not need to respond to a pressure difference of 1/4. Effects of the Invention As described above, according to the present invention, the pressure generated in the mixing pipe can be 21n in the case of TDRlln, so the fan and motor can be made smaller, and the solenoid valve can be used to adjust the load size, that is, the temperature sensor. Since it is turned on and off by the output, it can be switched very accurately, and since hysteresis is added to the on/off, there is no extra on/off, and good hot water temperature control performance can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a gas water heater showing an embodiment of the present invention, and FIG. 2 is a control circuit diagram thereof. 1...Main body, 2...Zero governor, 3.
...Solenoid valve, 4,6...Mixing pipe, 5,7
・・・・・・All primary air type gas burner, 11・・・・・・
・Heat exchanger, 13...Fan motor, 15...
...Temperature detector, E6B, E8...Air amount increase/decrease means.

Claims (1)

[Claims] 1 having at least two all-primary air type gas burners and one heat exchanger in the main body, two mixing tubes for mixing air and gas in each of the burners, and an amount of air in the mixing tube; a zero governor that controls the gas flow rate according to the temperature, a fan motor that forcibly performs air supply and exhaust, a temperature sensor that detects the hot water temperature, and a speed control that controls the fan motor speed according to the output of the temperature sensor. a circuit, and a control that outputs an off signal when the hot water temperature detected by the temperature detector is equal to or higher than a predetermined temperature higher than a set temperature, and outputs an on signal when the hot water temperature is lower than a second predetermined temperature lower than the set temperature. A gas water boiler comprising: a circuit; a solenoid valve that turns on and off the flow of gas into one of the mixing pipes in response to an on/off signal from the control circuit; and means for decreasing or increasing the amount of air in response to the on/off signal. vessel.