JPS63153360A - Output hot-water temperature controller for hot-water supplier - Google Patents

Abstract

PURPOSE:To make an input water temperature sensor unnecessary, obtain the whole of the title device inexpensively and facilitate the assembling of the same, by a method wherein feed-forward operation is effected based on an estimated input water temperature, a hot-water supplying amount detected by a flow rate sensor and a set temperature. CONSTITUTION:A flow rate sensor 2 detects the starting of the supply of hot-water and the output of a comparator 17 is changed from low to high at an instance when the detected flow rate has arrived at a value higher than a predetermined value Fs. This change is converted into a positive pulse by a differentiator 18 and becomes the clock input of a data latch 19 through a switch 22. A temperature, detected by an output hot-water temperature sensor 6 at this moment, becomes the data input of the data latch 19 and this temperature is stored and held. At the same time, a switch means 20 is switched from OFF into ON at this moment and the output of a control unit 15 is inputted into a heating amount regulating unit or a gas proportional valve 8 whereby a gas burner 9 starts combustion. A temperature, detected by the output hot-water temperature sensor 6 at this moment, is equal to an input water temperature because a heat exchanger 5 is not heated yet. Accordingly, the temperature, stored and held by the data latch 18 at this moment, becomes the input water temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a hot water temperature control device for a water heater, and more particularly to a hot water 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 a 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 heat exchange section 4
The hot water temperature is detected by the hot water temperature sensor installed at the outlet. Reference numeral 7 designates a gas passage, 8 a gas proportional valve serving as a heating amount adjustment unit that adjusts the amount of heating supplied to the heat exchanger 4, and 9 a gas burner that heats the heat exchanger 6. 10 is a control unit that performs feedforward control and feedback control;
Reference numeral 11 denotes a temperature setting section for setting the hot water temperature. Control part 1
0 includes a feedforward calculation section 12 that calculates a required heating amount in advance as a feedforward amount from the flow rate from the flow rate sensor 2, the inlet water temperature from the inlet water temperature sensor 6, and the set temperature from the temperature setting section 11; It consists of a feedback calculation unit 13 that calculates the amount of feedback necessary to compensate for the difference between the temperature and the tapped water temperature, and an addition unit 14 that adds the amount of feedforward calculation and the amount of feedback calculation. The output of the adder 14 is the output of the controller 10,
The sum of the calculation results of these two calculation units 12.13 determines the valve opening degree of the gas proportional valve 80, that is, the adjustment amount, that is, the gas flow rate, that is, the heating amount.

Problems to be Solved by the Invention In the conventional device described above, an inlet water temperature sensor is indispensable for feedforward control. Since processing of the mounting members and the water supply channel itself is required, 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 hot water temperature sensor without using an incoming water temperature sensor, and to perform a shifted forward calculation based on the 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 unit includes an inlet water temperature estimation unit 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 the amount of hot water supply, and an inlet water temperature estimation unit that outputs the outlet water temperature detected by the outlet hot water temperature sensor as the inlet water temperature, and the inlet water temperature estimation unit for a predetermined time after the flow rate sensor detects the hot water supply stop. The apparatus is provided with a timer section that prohibits the estimation operation of the section, and a feedforward calculation section that performs a feedforward calculation from the estimated incoming water temperature, the amount of hot water detected by the flow rate sensor, and the set temperature.

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. In addition, if hot water supply is restarted immediately after hot water supply is stopped, heated water (hot water) remains in the heat exchanger, and in this case, the hot water temperature sensor detects the temperature of such hot water, causing the heating It is expected that the temperature of the water before it is heated, that is, the temperature of the water entering the water, cannot be detected. However, the timer section prohibits the operation of the incoming water temperature estimating section for a predetermined time after the hot water supply has stopped, so even if hot water supply is restarted within the predetermined time after the hot water supply has stopped, the incoming water temperature estimating section will not operate, and the incoming water temperature estimating section will not operate. Since it continues to output the estimated temperature,
The above-mentioned inconvenience does not occur. This predetermined time is set to the time from when hot water supply stops until the heated residual hot water in the heat exchanger is sufficiently cooled.

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. Further, even in the case where hot water is resupplied immediately after hot water supply is stopped, the temperature of the residual hot water in the heat exchanger is not mistakenly set as the incoming water temperature, and the incoming water temperature can be estimated relatively accurately.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings. Note that the same parts as in the above conventional example are given the same reference numerals, detailed explanations are omitted, and different parts will be mainly explained.

In FIG. 1, 15 is a control section, 16 is an inlet water temperature estimation section, 12 is a feedforward calculation section, 13 is a feedback calculation section, 14 is an adder, 20 is a switch means, 2
A timer section 1 and a switch 22 forming a part of the timer section 21 are provided. Here, the incoming water temperature estimating section 16 estimates the incoming water temperature by inputting the flow rate from the flow rate sensor 2 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 includes a comparator 17 whose output changes from low to high when the flow rate from the flow rate sensor 2 exceeds a predetermined value F1, and a comparator 17 whose output changes from low to high. The output of the differentiator 18 is used as a clock input via the switch 22, and the hot water temperature from the hot water temperature sensor 6 is used as a data input. It consists of a data lunch 19 that stores and holds the temperature.

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. A timer section 21 starts operating when the output of the comparator 17 changes from high to low, and turns off the switch 22 for a predetermined period of time.

Next, the operation of the configuration of this embodiment will be explained. First, the flow rate sensor 2 detects hot water supply, and at the moment the detected value exceeds a predetermined value of 18, the output of the comparator 17 changes from low to high. This change is converted into a positive pulse by the differentiator 18, and becomes the clock input for the -y'-clutch 19 when the switch 22 is turned 11. The temperature detected by the outlet hot water temperature sensor 6 at this time is 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 1.5 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 outlet hot water temperature sensor 6 at this moment is equal to the inlet water temperature because the heat exchanger 6 has not yet been heated due to the physical delay of the gas proportional valve 8 and the gas burner 9. Therefore, the temperature stored and held by the data latch 18 at this time is the incoming water temperature.

Next, the hot water supply stops, the flow rate detected by the flow rate sensor 2 becomes less than the predetermined value 21, and the output of the comparator 17 changes from high to low. Due to this change, the timer unit 21 starts operating. Switch 22 is turned off for a predetermined period of time. Even if hot water supply is restarted within this predetermined time, the output of the comparator 17 changes from low to high and the differentiator 18 outputs a positive P/R, but since the switch 22 is off, this output is It is not input to the data latch 19. Therefore, the contents of the data latch 19 are not updated, and the previously stored temperature is output as the incoming water temperature.

When a predetermined period of time has elapsed since the hot water supply was stopped, the operation of the timer section 21 ends and the switch 22 is turned on again. After that, when hot water supply starts, the switch 22 is on, so the positive pulse from the differentiator 18 is input as the clock input of the data latch 19, and the temperature detected by the outlet hot water temperature sensor 6 at that time is the incoming water temperature. The data is newly stored in the data latch 19 and output as the incoming water temperature. At this point, the temperature of the residual hot water in the heat exchange section 4 has sufficiently decreased and is almost equal to the incoming water temperature, so the temperature detected by the outlet hot water temperature sensor 6 at this point is almost equal to the incoming water temperature.

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, so it 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. Changes such as using other appropriate means for the heating amount adjusting section can be easily implemented without departing from the spirit of the present invention.

Effects of the Invention As described above, according to the present invention, since the incoming water temperature is estimated using the outlet temperature sensor without using an incoming water temperature sensor, compared to the conventional method using an incoming water temperature sensor, It can be made inexpensive and can be assembled easily. Furthermore, since the inlet water temperature is always estimated at the start of hot water supply, large errors do not occur. Furthermore, even if hot water supply is stopped and there is still residual hot water in the heat exchanger, even if the hot water supply is restarted, the timer unit will be disabled. Malfunctions such as estimating the hot water temperature as the incoming water temperature do not occur.

[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, 12... Feedforward calculation section , 16
. . . Control section, 16 . . . Incoming water temperature estimation section, 21, . . . Timer section. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (1)

[Claims] A flow rate sensor provided in the water supply channel, a hot water temperature sensor provided at the outlet of the heat exchange section, a heating amount adjustment section that adjusts the amount of heating supplied to the heat exchange section, and a temperature setting section that sets the temperature of hot water discharged. , a control unit that determines the adjustment amount of the heating amount adjustment unit from the hot water supply amount detected by the flow rate sensor, the hot water temperature detected by the hot water output temperature sensor, and the set temperature set by the temperature setting unit, The control unit includes an inlet water temperature estimating unit 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, and a feed unit that performs feedforward calculation from the hot water supply amount, inlet water temperature, and set temperature. A hot water outlet temperature control device for a water heater, comprising a forward calculation section and a timer section that prohibits the estimation operation of the water inlet temperature estimating section for a predetermined period of time after the flow rate sensor detects the stop of hot water supply.