JPH0332931Y2 - - Google Patents

Description

[Detailed description of the invention] <Field of industrial application> The present invention relates to a water heater that has stable hot water output characteristics when the amount of hot water supply is stable and when hot water supply is intermittent.

<Prior Art> A conventional example of a gas water heater is shown in Fig. 2. 1 is a water supply channel in the water heater, 2 is a water flow sensor installed in the water supply channel that detects the amount of hot water supplied, 3 is a heat exchange section, 4 is a hot water outlet temperature sensor 5 that detects the hot water temperature, is a passage for gas serving as fuel, 6 is a gas proportional valve that adjusts the gas amount, 7 is a hot water temperature control circuit, 8 is a temperature setting circuit for setting the hot water temperature, 9 is an integral circuit that stabilizes the output of the water amount sensor, and 11 is an adjustment of the hot water amount at the hot water supply destination. It is a faucet. The control circuit 7 opens the gas proportional valve 6 based on the heat amount deviation obtained by multiplying the temperature deviation obtained by subtracting the hot water temperature detected by the hot water temperature sensor 4 from the hot water supply temperature set in the temperature setting circuit 8 by the hot water supply amount detected by the flow rate sensor 2. By adjusting the temperature, stable hot water temperature control can be performed in response to changes in the amount of hot water supplied and changes in the set hot water supply temperature. At this time, the integrating circuit 9 is provided to average instantaneous flow rate changes due to water pressure fluctuations in the water supply channel and measurement irregularities of the flow rate sensor 2, and to obtain a stable hot water temperature during steady hot water supply.

<Problems to be Solved by the Invention> The drawback of this conventional method is that when the hot water supply is stopped by the faucet 11 at the hot water supply destination, the control to stop the fuel and extinguish the fire is delayed by the integral delay time by the integral circuit 9. Therefore, during this delay time, hot water accumulates in the heat exchanger 3 from the water supply channel 1, and the hot water is discharged from the faucet 11 the next time it is used, which is dangerous.

<Means for Solving the Problems> In the present invention, in order to solve the above-mentioned drawbacks of the conventional method, an integrating circuit 10 with a small integration delay time is provided in addition to the integrating circuit 9, and the output of the integrating circuit 10 is used to solve the problem. Stop the fuel supply to 3.

<Function> The output of the integral circuit 9 is used as the flow rate when controlling the hot water temperature, but the output of the newly provided integral circuit 10 is used when stopping combustion.

<Example> Fig. 1 shows an example of the present invention. This configuration is obtained by adding an integrating circuit 10 to the conventional configuration shown in FIG. This operation is for example 400mS during normal operation.
The number of output pulses from the water flow sensor during this period is integrated by an integrating circuit 9, and the hot water temperature is controlled based on the average value.
Then, when the faucet 11 is closed and the pulse output of the water level sensor becomes 0, the integral value of the integrating circuit 10 of the water level sensor output pulse for 30 mS, for example, becomes 0.
Check that it is, and then stop combustion.

By performing such processing, stable hot water output characteristics can be obtained during steady combustion, as the hot water temperature is controlled by the average value of the output pulse number over a relatively long period of time from the water flow sensor, and combustion stoppage is not necessary. Since the combustion is stopped after confirming that the number of pulses is 0 for a sufficiently short period of time (for example, 30 mS), it is possible to safely control the hot water temperature with no inconvenient operation and little after-boiling.

FIG. 3 shows a detailed embodiment of the invention. 12 is a waveform shaping circuit that shapes the output pulse from the flow rate sensor; 13 is a variable resistor for setting hot water temperature; 14;
16 is a reference resistance value for comparing thermistor resistance values, 15 is a thermistor for detecting incoming water temperature, 16 is a thermistor for detecting outlet water temperature, 18 is a multiplexer for selecting data to be input to the microcontroller 19 is a voltage determined by the thermistor and variable resistor The A/D converter 20 that converts the value into a digital value is a microcomputer that integrates the flow rate sensor output and controls the temperature.
is an input port PC, PD is an output port, and 21 is a D/A converter that outputs the microcomputer calculated value to the proportional valve. The microcomputer 20 has an internal timer and counts the number of flow pulses P ₁ for a certain period of time T ₁ . The flow rate at this time is given by k·P ₁ /T ₁ . For example, set the period for measuring this pulse number to 400mS and 30mS.
By changing to , it is possible to obtain the output of an integrating circuit with a different time constant, ie, an integrating circuit, etc.

<Effects of the invention> As described above, by having a plurality of integral circuits, a stable hot water temperature can be obtained during steady hot water supply, and abnormally high temperature hot water can be prevented even when hot water supply is interrupted.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of a conventional embodiment, and FIG. 3 is a detailed electrical circuit diagram of an embodiment of the present invention. 1... Water supply channel, 2... Flow rate sensor, 3... Heat exchange section, 4... Temperature sensor, 5... Fuel path, 6...
Fuel control valve, 7... control circuit, 8... temperature setting circuit, 9, 10... integral circuit, 11... faucet.

Claims (1)

[Scope of utility model registration request] Fuel is supplied to the water supply channel, a flow rate sensor installed in the middle of the water supply channel, a heat exchange section provided in the middle of the water supply channel, and a temperature sensor installed on the hot water outlet side of the heat exchange section that detects the hot water temperature and the heat exchange section. A fuel path, a fuel control valve provided in the middle of the fuel path to adjust the flow rate of fuel, a temperature setting circuit to set the hot water temperature, and a temperature setting between the hot water temperature detected by the temperature sensor and the set temperature set by the temperature setting circuit. In a control circuit for a water heater having a hot water outlet temperature control circuit that determines the opening degree of a fuel control valve based on the deviation and the amount of hot water detected by the flow rate sensor, a plurality of integral circuits with different time constants stabilize the output of the flow rate sensor. A water heater control circuit comprising: