JPS63169441A - Output hot-water temperature controller for hot-water supplier - Google Patents

Abstract

PURPOSE:To make an input water temperature sensor unnecessary and manufacture the whole of the title controller inexpensively, by a method wherein feedforward operation is effected by an input water temperature, estimated by an output hot-water temperature sensor. CONSTITUTION:An input water temperature estimating unit 16 inputs the flow rate of a flow rate sensor 2 and an output hot-water temperature from an output hot-water temperature sensor 6 to estimate an input water temperature and output it to a feedforward operation unit 12. At an instance when the flow rate sensor 2 has detected the supply of hot-water and the the value of flow rate has exceeded a predetermined value Fs, the output of a comparator 17 is inputted into the clock of a data latch 19. The output hot-water temperature, detected by the output hot-water temperature sensor 6 at this moment, is inputted into the data latch 19. Simultaneously, the combustion of a gas burner 9 is started. A temperature, detected at this instance by the temperature sensor 6, is equal to the input water temperature, since a heat exchanger 5 is not heated yet. When hot-water supply is restarted immediately after stopping the supply of hot-water, the temperature of hot-water, remaining in the heat exchanger 5, is detected by the temperature sensor 6 and, subsequently, the hot-water temperature approaches the input water temperature quickly. Accordingly, a time gradient, operated in the operating unit 21 of temperature gradient, is increased and the comparing unit 22 turns a switch 23 off.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a hot water outlet temperature control device for hot water supply, and more particularly to a hot water outlet temperature control device using feedforward control.

2. Description of the Related Art As a conventional hot water outlet temperature control device of this type, there is a
The structure was as shown in the figure.

That is, a flow rate sensor 2 for detecting the amount of hot water supplied and an inlet water temperature sensor 3 for detecting the inlet water temperature are provided in the water supply channel 1 of the water heater. 4 is a heat exchange section, and 5 is a heat exchanger, in which water supplied by the heat exchange section 4 is heated and supplied as hot water. 6 is a hot water temperature sensor installed at the outlet of the heat exchanger, which detects the hot water temperature;
Reference numeral 7 designates a gas passage, 8 a gas proportional valve serving as a heating amount adjusting section for adjusting the amount of heating supplied to the heat exchange section 4, and 9 a gas burner. Reference numeral 10 represents a control section that performs feedforward control and feedback control, and reference numeral 11 represents a temperature setting section that sets the hot water temperature. The control unit 10 controls the flow rate from the flow rate sensor 2, the inlet water temperature from the inlet water temperature sensor 6, and the temperature setting unit 1.
a feedforward calculation unit 12 that calculates a necessary heating amount in advance from the set temperature from 1 as a feedforward amount, and a feedback calculation unit that calculates a feedback amount necessary to compensate for the difference between the set temperature and the hot water temperature. 13, an adder 14 that adds the amount of feedforward calculations and the amount of feedback calculations. The output of the adder 14 is the output of the controller 10, and these two arithmetic units 12.
The sum of the calculation results of 13 determines the valve opening degree, ie, the adjustment amount, ie, the gas flow rate, ie, the heating amount, of the gas proportional valve 8.

Problems to be Solved by the Invention In the conventional device described above, an inlet water temperature sensor is indispensable for feedforward control. Since it is necessary to process the mounting members and the water supply channel itself, the entire device is not only expensive but also complicated to assemble.

Therefore, the present invention attempts to estimate the incoming water temperature using an outlet water temperature sensor, without using an incoming water temperature sensor, and to perform a feedforward calculation using this estimated incoming water temperature.

Means for solving the problems and technical means of the present invention for solving the above problems are as follows:
The control section includes an inlet water temperature estimating section that outputs the outlet hot water temperature detected by the outlet hot water temperature sensor when the flow rate sensor detects the amount of hot water supplied as the inlet water temperature, a gradient calculation section that calculates the gradient of the outlet hot water temperature, and a gradient calculating section that calculates the gradient of the outlet hot water temperature. A comparison section is provided that prohibits the estimation operation of the incoming water temperature estimating section when the incoming water temperature is out of range, and a feedforward calculation section is provided that performs feedforward calculation from the estimated incoming water temperature, the hot water supply amount detected by the flow rate sensor, and the set temperature. be.

For production The effect of this technical means is as follows.

That is, a certain time delay normally occurs after hot water supply starts and the flow rate sensor detects the amount of hot water supplied, until the heat exchange section is heated. For example, if a gas burner is used in the heat exchange section as in the conventional example, there will be a time delay until the gas burner is ignited due to the ignition delay of the gas burner. During this period, from when the flow rate sensor detects hot water supply until the heat exchange section is heated, the water is not heat exchanged in the heat exchange section and is supplied, and the hot water temperature sensor is During this period, the detected hot water temperature is equal to the incoming water temperature. Therefore, the temperature detected by the outlet hot water temperature sensor during this period can be taken as the incoming water temperature.

Next, when hot water supply is stopped and then restarted, heated water (hot water) remains in the heat exchanger, and the temperature of this residual hot water is first detected by the outlet hot water temperature sensor, and the temperature of this hot water is detected by the inlet hot water temperature sensor. It is expected that the temperature will be high. However, the gradient calculation unit calculates the time gradient of the hot water temperature,
In this case, when hot water supply is restarted immediately after stopping hot water supply,
The temperature detected by the outlet hot water temperature sensor gradually approaches the inlet water temperature from the temperature of the residual hot water in the heat exchanger, resulting in a relatively large gradient. The comparison section compares this slope with a predetermined range,
If the gradient is outside the predetermined range, a prohibition signal is output to prohibit the estimation operation of the inlet water temperature estimator. Therefore, when hot water supply is restarted after stopping water supply, if there is residual hot water in the heat exchanger, the temperature detected by the outlet hot water temperature sensor at that time will rapidly decrease from the residual hot water temperature toward the inlet temperature, with a time gradient of is large, the comparator outputs a prohibition signal and prohibits the incoming water temperature estimation operation. Also, if a relatively long period of time has passed after hot water supply has stopped, the temperature of the remaining hot water in the heat exchanger will drop and become equal to the water input temperature, so if hot water supply is restarted in this condition,
The temperature detected by the hot water temperature sensor does not change much.
Therefore, the time gradient is also small, the comparator does not output a prohibition signal, and the incoming water temperature estimating unit performs the estimation operation and outputs the temperature detected by the outlet hot water temperature sensor at that time as the incoming water temperature.

As a result, there is no need for an inlet water temperature sensor, which was required in the past, and the entire device is made cheaper and easier to assemble than in the past. In addition, if hot water supply is resumed immediately after hot water supply is stopped, the operation of the incoming water temperature estimation part is prohibited by the gradient calculation part and the comparison part, so it is possible to mistakenly estimate the temperature of the hot water remaining in the heat exchange part as the incoming water temperature. Therefore, the water entering temperature can be estimated relatively accurately.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings.

In FIG. 1, reference numeral 15 denotes a control section, which includes an inlet water temperature estimation section 16, a feedforward calculation section 12, a feedback calculation section 13, an adder 14, and a switch means 20. Here, the inlet water temperature estimating section 16 includes the flow rate sensor 2
The incoming water temperature is estimated by inputting the flow rate of the flow rate and the outlet hot water temperature from the outlet hot water temperature sensor 6, and outputs it to the feedforward calculation section 12.

As shown in the figure, a specific configuration example of the inlet water temperature estimating unit 16 is such that the flow rate from the flow rate sensor 2 is a predetermined value 231. Comparator 17 and comparator 1 whose output changes from low to high when the
A differentiator 18 converts the change in the output of 7 from low to high into a positive pulse, and the output of the differentiator 18 is used as a clock input via a switch 23 forming a part of the comparator 22, and the output from the hot water temperature sensor 6 The temperature of the hot water at the outlet is taken as a data input, and the clock input is constituted by a data latch 19 that stores and holds the temperature at the time of the input of the hot water. 20 is a switch means that is turned on when the output of the comparator 17 is high and turned off when the output is low.

Reference numeral 21 denotes a gradient calculation unit that calculates the time gradient of the temperature detected by the hot water temperature sensor 6. 22 is a comparison section, and gradient calculation section 2
When the time gradient calculated in step 1 is outside a predetermined range, a prohibition signal is output and the switch 23 is turned off.

Next, the operation of the configuration of this embodiment will be explained. First, the flow rate sensor 2 detects hot water supply, and the moment the detected value exceeds a predetermined value Fg, the output of the comparator 17 changes from low to high. This change is converted into a positive pulse by the differentiator 18,
It becomes the clock input of the data latch 19 via the switch 23. The temperature detected by the outlet hot water temperature sensor 6 at this time becomes the data input to the data latch 19, and this temperature is stored and held. At the same time, the switch means 20 is turned on from off, the output of the control section 15 is input to the gas proportional valve 8 as a heating amount adjusting section, and the gas burner 9 starts combustion based on the output. The temperature detected by the hot water temperature sensor 6 at this moment is because the heat exchanger 5 has not yet been heated due to the physical delay of the gas proportional valve 8 and gas burner 9.
Equal to the incoming water temperature. Therefore, the temperature stored and held by the data latch 18 at this time is the incoming water temperature.

When hot water supply is resumed immediately after hot water supply is stopped, the temperature of the hot water remaining in the heat exchanger 5 is first detected by the outlet hot water temperature sensor 6, and then rapidly approaches the incoming water temperature. Therefore, in this case, the time gradient calculated by the gradient calculation section 21 of the temperature detected by the hot water temperature sensor 6 becomes large and falls outside the predetermined range of the comparison section 22, so the comparison section 22 outputs a prohibition signal and the switch 23 is turned off. Turn off. Therefore, in such a case, differentiator 1
Since the positive pulse of 8 is not input to the data latch 19,
The data held in the memory of the toe latch 19 is saved and not updated. In other words, the previously estimated incoming water temperature is output as is.

When a relatively long period of time has passed since the hot water supply stopped, the temperature of the residual hot water in the heat exchange section 4 has decreased, and the hot water supply is resumed at a state that is almost equal to the incoming water humidity, the outlet hot water temperature sensor 6 detects the temperature at this time. The time gradient calculated by the temperature gradient calculation unit 21 is almost zero and is within the predetermined range of the comparison unit 22, so
The comparator 22 has the switch 23 turned on. Therefore, in such a case, the positive pulse that is the output of the differentiator 18 will not be the clock input to the data latch 19, and the data latch 19 will store and hold the temperature detected by the outlet water temperature sensor 6 at that time as the new inlet water temperature. Output.

In this way, the feedforward calculation unit 1 uses the incoming water temperature estimated by the incoming water temperature detection unit 16 at the start of hot water supply.
2 performs a feedforward operation. Since the incoming water temperature usually changes slowly depending on the season, there is no large error in the incoming water temperature estimated in this embodiment. Furthermore, even if the inlet water temperature changes over time from the inlet water temperature at the time of estimation, since the inlet water temperature at the estimated time is output from the inlet water temperature estimating unit 16, the calculation result of the feedforward calculation unit 12 Although an error occurs, this error is compensated by feedback control and does not pose a practical problem.

In this embodiment, a gas burner is used in the heat exchange section and a gas proportional valve is used in the heating amount adjustment section. Further, changes such as using other appropriate means in the heating amount adjusting section can be easily implemented without departing from the spirit of the present invention.

Effects of the Invention According to the present invention, since the incoming water temperature is estimated by the outlet temperature sensor without using the incoming water temperature sensor,
Compared to the conventional method using an inlet water temperature sensor, the cost can be lowered and assembly can be made easier. Furthermore, since the inlet water temperature is always estimated at the start of hot water supply, large errors do not occur.

Furthermore, when hot water supply is restarted immediately after hot water supply is stopped, the temperature of the remaining hot water in the heat exchanger is not mistakenly estimated to be the incoming water temperature, and relatively accurate estimation can be performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a hot water outlet temperature control device for a water heater according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional hot water outlet temperature control device for a water heater. 2...Flow rate sensor, 4...Heat exchange section, 6
... Hot water temperature sensor, 8 ... Gas proportional valve as heating amount adjustment section, 11 ... Temperature setting section, 1
2...Feedforward calculation section, 15...
. . . Control unit, 16 . . . Incoming water temperature estimation unit, 21
. . . Gradient calculation section, 22 . . . Comparison section. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (1)

[Claims] A flow rate sensor installed in the water supply channel of the water heater, a hot water temperature sensor installed at the outlet of the heat exchange section of the water heater, a heating amount adjustment section that adjusts the amount of heating supplied to the heat exchange section, and a heating amount adjustment section that adjusts the temperature of the hot water output. control for determining the adjustment amount of the heating amount adjustment section from the temperature setting section to be set, the amount of hot water detected by the flow rate sensor, the outlet temperature detected by the outlet temperature sensor, and the set temperature set by the temperature setting section; and an inlet water temperature estimating part that outputs the outlet hot water temperature detected by the outlet hot water temperature sensor as the inlet water temperature when the flow rate sensor detects hot water supply; a feedforward calculation unit that performs a feedforward calculation; a gradient calculation unit that calculates the gradient of the outlet hot water temperature; and an estimation operation of the inlet water temperature estimation unit when the gradient of the outlet hot water temperature calculated by the gradient calculation unit is above a predetermined range. A hot water outlet temperature control device for a water heater, comprising a comparison section that prohibits