JPS6235576B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to hot water outlet temperature control for water heaters using gas, oil, electricity, etc. as heat sources, and eliminates the disadvantage of conventional devices that the set hot water temperature cannot be obtained when overloaded. The purpose is to provide a new control device that can obtain the desired hot water temperature.

The explanation will be given below using a gas water heater as an example.

FIG. 1 is a block diagram of a conventional gas water heater, in which combustion heat in a burner 1 and water are exchanged in a heat exchanger 2 to provide hot water. The temperature controller 3 receives the signal TW from the hot water temperature detector 4 and the signal from the temperature setting device 5.
TWR is input, a predetermined combustion amount is determined from the difference between the TW and TWR, and a control signal is output to the supply heat amount controller 6 to control the hot water temperature. Here, as the hot water temperature control 4, for example, a thermistor, a temperature controller 3
A PiD controller etc. is often used.

FIG. 2 is a diagram showing the relationship between the hot water output amount W of the gas water heater and the temperature rise ΔT. The solid line represents the characteristics at the maximum combustion amount. In other words, the maximum combustion amount Q _g
nax , temperature rise ΔT, and flow rate W are as follows, where η is the combustion efficiency, η・Q _{g nax} =W・ΔT...(1), and ΔT=η・Q _{g nax} /W...(2) It is. Therefore, the temperature rise Δ above that indicated by the solid line
T does not exist. For example, when the maximum combustion amount Q _{g nax} and the hot water output amount is W ₁ , the temperature rise ΔT becomes ΔT ₁ as shown in the figure. The temperature controller 3 described above operates effectively when the temperature rise is ΔT=ΔT ₁ and the hot water output amount W is less than W ₁ . If W＞
At W ₁ , control becomes impossible and the hot water temperature TW cannot reach the set temperature TWR.

In this way, the amount W of hot water that can be controlled by the hot water temperature is limited by the maximum combustion amount Q _{g nax} .
This phenomenon is not limited to gas water heaters, but also applies to water heaters using other fuels.

The present invention provides a hot water temperature control device that eliminates the drawbacks seen in the hot water temperature control of the conventional water heater described above.
TWO is what you get.

FIG. 3 is a block diagram of the gas water heater of the present invention.
The water flow controller 7 receives a signal from the hot water temperature detector 4.
TW, the signal TWR from the temperature setting device 5, and
It inputs the output of the temperature controller 3 and also has a timer section 8 for generating a predetermined time inside. Then, based on the difference TER between the signals TW and TWR mentioned above and the signal from the timer section 8, a signal for controlling the supply water amount control device 9 is output. Components with the same numbers as those in FIG. 1 are devices having the same functions.

When starting to use the gas water heater, the supply water flow control device 9 is initialized so that the maximum flow rate W _{g nax} is obtained, and after a predetermined period of time has elapsed by the timer section 8, which starts counting at the same time as the start of use, The amount of heat supplied by the water heater is maximum, and the set temperature TWR and hot water temperature are the same.
When the difference between TER and TW is equal to or higher than the temperature deviation value within the allowable range for water heater use, the above
The water supply amount control device 9 is operated to reduce the amount of water supplied according to TER, and the amount of water is controlled so that TER approaches zero. Further, the timer section 8 starts counting when a deviation in the outlet temperature TW occurs when a change in the set temperature occurs or when a load fluctuation occurs, that is, when the TER exceeds the temperature deviation value within the above-mentioned allowable range. However, as described above, the water supply amount control device 9 is operated according to the state of the amount of heat supplied to the water heater and the temperature deviation TER after a predetermined period of time has elapsed, and the set hot water temperature is obtained. At this time, the predetermined time refers to the control performance of the temperature controller (for example, in the case of PiD control, it depends on the adjusted values of each parameter) and the process delay time, from a transient state to a steady state (including insufficient capacity). This corresponds to the time it takes to calm down. In addition, after a predetermined period of time has elapsed, if the amount of heat supplied to the water heater is not at its maximum, the water supply amount control device 9 is operated to increase the amount of water supplied, so that the set water temperature can be obtained at the maximum flow rate determined by the operation at the hot water supply point. Make it.

Figure 4 shows water temperature characteristics a by the gas water heater of the present invention.
and the hot water output control characteristic b. The horizontal axis indicates the elapsed time t, which is the case when use is started at t=0. After the start of use, a predetermined period of time has passed t=t ₁
Based on the amount of heat supplied to the water heater and the deviation TER, the amount of water supplied is reduced from W _nax to W ₁ , and the TER is controlled to approach zero. At t= _t2 , a predetermined period of time has elapsed after the flow rate change, and the water flow rate control operation determination is performed in the same manner as described above.

As described above, according to the present invention, the amount W of hot water dispensed is always limited to a range in which the temperature of hot water dispensed can be controlled, so hot water of a desired temperature can be obtained. In addition, it has a timer element that takes into account delay in response of the system to setting changes and load fluctuations, so there is no unnecessary water supply amount control operation in terms of hot water temperature control, and hot water temperature characteristics can be improved. .

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a conventional gas water heater, Fig. 2 is a characteristic diagram showing the relationship between hot water output amount and temperature rise of the gas water heater of Fig. 1, and Fig. 3 is an embodiment of the present invention. FIGS. 4a and 4b are diagrams showing the response characteristics of the hot water temperature and the amount of hot water produced by the control device of the present invention, respectively. 3... Temperature controller, 4... Hot water temperature detector, 5
... Temperature setting device, 6 ... Water heater supply heat amount controller,
7...Water flow rate controller, 8...Timer section, 9...Water supply flow rate control device.

Claims (1)

[Claims] 1 Water heater outlet temperature detector, temperature setting device,
a temperature controller that outputs a signal for controlling the amount of heat supplied to the water heater depending on the difference (TER) between the signal of the temperature setting device and the signal of the hot water temperature detector; and a water heater that responds to the output of the temperature controller. A supply heat amount controller and a timer unit that starts counting when the water heater starts to be used, when the signal of the temperature setting device changes, or when the deviation (TER) changes by more than a temperature deviation value within an allowable range for use of the water heater. and a water flow controller that outputs a signal to control the water flow when the deviation (TER) is equal to or higher than the temperature deviation value in the allowable range when the timer section finishes counting, and a water flow controller that responds to the output of the water flow controller. A water heater control device comprising: a water supply amount control device that controls the amount of water supplied to the water heater.