JPH07243699A - Hot water feeding-temperature control device - Google Patents

Abstract

PURPOSE:To improve hot water feeding temperature characteristics substantially by a method wherein the hot water feeding temperature at the time of starting the hot water feeding is rapidly stabilized. CONSTITUTION:A micro-processor 6 determines an accumulated flow rate point where a proper hot water feeding temperature can be attained in response to a hot water feeding time, a hot water feeding stopping time and a serial number of a hot water feeding device. A feed-forward control based on an output of a water feeding temperature sensor 1 is carried out until the accumulated flow rate from the starting of hot water feeding reaches the accumulated flow rate point,and then only a feed-back control or both feed-back control and a feed-forward control are carried out in response to a value of a hot water feeding temperature sensor 2, after the value exceeds the accumulated flow rate point.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot water supply temperature control device capable of hot water whose temperature is controlled to a predetermined value when hot water is started.

[0002]

2. Description of the Related Art Conventionally, fuel supply and combustion and heating of a heat exchanger by this combustion are performed in parallel by hot water discharge operation such as opening of a water faucet, and at the water inlet side of this heat exchanger. Water heaters that automatically control the hot water temperature to a preset value based on the outputs of the hot water temperature sensor and the hot water temperature sensor provided on the hot water outlet side are widely used. In such a water heater, hot water heated to the set temperature in the heat exchanger is automatically poured out by the tapping operation, for example, opening of the faucet as described above.

In this case, when the hot water supply time is long and, for example, the opening and closing of the faucet is repeated relatively frequently, the water in the pipe is warmed by the heat quantity of the heat exchanger even after the hot water has been discharged. There was hot water with a relatively high temperature from the beginning of the reopening of the tap.On the other hand, if the hot water supply was started after a considerable time, the temperature of the hot water at the beginning of the hot water due to the reopening of the faucet was low, but after that, The desired heating control of the corresponding heat exchanger is performed.

[0004]

Since the conventional hot water supply apparatus is configured as described above, in the hot water discharge control, when a certain amount of time has not passed from the end of the last hot water discharge,
As shown in FIG. 4, at the start of tapping, the tapping temperature is
Initially, a small undershoot A is generated due to the cooling of the piping inside the water heater, and further an overshoot B is generated due to the amount of heat retained in the heat exchanger.

After the overshoot is followed by an undershoot C due to the amount of water flowing until ignition after a heat request is made, PID control based on the output of the hot water temperature sensor for this undershoot C is performed. , Overshoot D due to excessive control of this
However, there is a problem in that the hot water outlet temperature is not stabilized early due to the undershoot and overshoot that occur one after another.

The present invention has been made in view of the above-mentioned conventional problems, and provides a hot water supply temperature control device capable of rapidly stabilizing the hot water temperature at the start of hot water discharge and greatly improving the hot water temperature characteristics. The purpose is to get.

[0007]

In the hot water supply temperature control device according to the present invention, the microprocessor determines an integrated flow rate point at which an appropriate hot water temperature can be obtained based on the hot water discharge time, the hot water discharge stop time, and the number of hot water heaters. Feed forward control based on the output of the water temperature sensor until the accumulated flow rate from the start of hot water reaches the accumulated flow point.
After the cumulative flow rate point is exceeded, only the feedback control based on the hot water temperature sensor or the feedback control and the feedforward control are performed.

[0008]

The hot water supply temperature control device according to the present invention has an integrated flow rate point determined from the time of the previous hot water discharge, the number corresponding to the amount of heat generated by the water heater, and the time from the end of the previous hot water discharge to the re-hot water discharge, and the integration from the start of the hot water discharge. If the integrated flow rate is smaller than the integrated flow rate point by comparing the magnitude with the flow rate in a microprocessor, avoid PID control that causes a delay based on the output of the hot water temperature sensor, and feed based on the output of the incoming water temperature sensor. When the forward control is performed and the integrated flow rate exceeds the integrated flow rate point, feedback control is performed based on the output of the hot water temperature sensor.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numerals 1 and 2 are provided on a water inlet side and a hot water outlet side of a heat exchanger of a water heater, respectively, for detecting a water inlet temperature and a hot water outlet temperature, and a hot water outlet temperature sensor, and 3 is a hot water outlet time of the water heater. And a timer for measuring the hot water discharge stop time from the hot water discharge stop to the hot water discharge again.

Numeral 4 is a memory for storing the number of the hot water heater being used, and numeral 5 is a flow rate sensor for measuring the integrated flow rate of the incoming water from the start of the hot water discharge.

Further, 6 is a microprocessor which determines an integrated flow rate point at which an appropriate hot water discharge temperature can be obtained based on the hot water discharge time, the hot water discharge stop time and the number of symbols above, and the integrated flow rate of the integrated flow rate with respect to the integrated flow rate point is determined. Depending on the size, the hot water temperature sensor 1 or both the hot water temperature sensor 2 and the hot water temperature sensor 2 serve to perform hot water discharge control.

Reference numeral 7 is a temperature setter for arbitrarily setting the outlet heated water temperature, and 8 is a proportional valve for controlling the flow rate of fuel according to the calculation result of the microprocessor 6.

FIG. 2 is an explanatory view showing a schematic structure of the water heater, and 11 is a heat exchanger connected to a water pipe 12, which guides the hot water heated here to a faucet (not shown). On the inlet side and outlet side of the heat exchanger 11, the above-mentioned outlet temperature sensor 2, such as an inlet temperature thermistor, a water temperature sensor 1, a flow rate sensor 4, and an outlet temperature thermistor are installed.

Further, 13 is a fuel pipe for supplying fuel gas, a combustor 14 facing the lower part of the heat exchanger 11 is connected to one end of the fuel pipe 13, and fuel is supplied in the middle of the fuel pipe 13. The proportional valve 8 for adjusting the quantity is provided.

Next, the operation will be described with reference to the flowchart of FIG. First, in controlling the hot water supply temperature, the desired hot water temperature is set in advance by the temperature setting device 6, and the faucet is opened. As a result, water enters the heat exchanger 11 through the water pipe 12.

Further, based on the temperature setting input of the temperature setter 7 and the like, the opening control of the proportional valve 8 and the like are performed, and the fuel is supplied to the combustor 14 through the fuel pipe 13.
The fuel is ignited, the fuel is burned, and the heat exchanger 11 is heated.

Therefore, the water in the heat exchanger 11 is heated to a temperature at which the above set temperature can be obtained, and the hot water is discharged from the faucet.
In the present invention, the following hot water supply temperature control is performed under the control of the microprocessor 5 based on the detection outputs of the water inlet temperature sensor 1 on the water inlet side and the hot water outlet temperature sensor 2 on the hot water outlet side of the heat exchanger 11. It

That is, first, when a heat request is made in response to an opening operation of the faucet (step ST1), the timer 3
Measures the hot water discharge time T ₁ after the heat request (step ST2) and uses the number (heat quantity) C ₁
Is stored in the memory 4 (step ST3).

Here, the microprocessor 6 determines whether or not the heat request has been released (step ST4). If the heat request has not been released yet, the hot water discharge control is carried out, and the processing from step ST2 onward is executed. Yes (step ST
5). On the other hand, when the heat request is released, that is, when the faucet is closed, the hot water discharge stop time T ₂ from the release of the heat request until the hot water is again discharged until the next heat request is made. The timer 3 measures (counts up) (step ST6).

Next, from the stopped state of the faucet, which is the release of the heat demand, it is judged again whether or not there is a heat demand, that is, whether or not the faucet is opened (step ST7), and there is a heat demand. In this case, the microprocessor 6 causes the integrated flow rate point P ₁ to obtain an appropriate hot water discharge temperature based on the hot water discharge time T ₁ , the number C _1, and the hot water discharge stop time T _2.
Is determined (step ST8).

When there is a heat demand as described above, after determining the integrated flow rate point P ₁ , the tapping time T _1a is measured again by the timer 3 (step ST9), and the used number C _{1a is} also used. After registering in memory 4 (step S
T10), it is determined whether or not the integrated flow rate P _1a from the start of hot water measured by the flow rate sensor 5 exceeds the integrated point P ₁ (step ST11),

As a result of this judgment, when the integrated flow rate P _1a does not exceed the integrated flow rate point P ₁ , the hot water temperature overshoots due to the amount of heat retained in the heat exchanger 11, undershoot due to the amount of water before ignition and its undershoot. In order to avoid overshoot due to excessive PID control for avoiding shoots, the outlet temperature control by feedback control based on the output of the outlet temperature sensor 2 is not performed, but the feedforward control based on the output of the inlet temperature sensor 1 is performed. Hot water discharge control data for the calculation is calculated (step ST12).

On the other hand, as a result of the above judgment, when the integrated flow rate P _1a exceeds the integrated flow rate point P ₁ , the overshoot or undershoot of the tapping temperature becomes small, which may lead to excessive PID control, for example. Therefore, the hot water discharge control data for feed forward control based on the output of the incoming water temperature sensor 1 and the hot water discharge control data for feedback control based on the output of the hot water temperature sensor 2 are calculated (step ST13).

When any of these steps ST12 and ST13 is performed, hot water discharge control is performed based on the result of each operation (step ST1).
4) If the heat request is canceled here (step S
T15), the hot water discharge time T _1a and the used number C _1a are held for the determination of the next integrated flow rate point, and step ST
The processing of 6 and below is executed (step ST16).

When it is determined in step ST15 that the heat request has not been released yet, step ST15
The processing of 9 or less will be repeatedly executed.

[0026]

As described above, according to the present invention, the microprocessor is caused to determine the integrated flow rate point at which an appropriate hot water temperature can be obtained based on the hot water discharge time, the hot water discharge stop time, and the number of hot water heaters, and the hot water discharge start is started. Feed-forward control based on the output of the incoming water temperature sensor until the accumulated flow rate reaches the accumulated flow rate point, and after exceeding the accumulated flow point, only feedback control based on the outlet temperature sensor or this feedback control and the feed-forward control Since it is configured to perform the above, there is an effect that it is possible to rapidly stabilize the tapping temperature at the start of tapping and greatly improve the tapping temperature characteristic.

[Brief description of drawings]

FIG. 1 is a block diagram showing a hot water supply temperature control device according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a water heater used for hot water temperature control of the present invention.

FIG. 3 is a flowchart showing a hot water supply temperature control procedure according to the present invention.

FIG. 4 is a conventional tapping temperature characteristic diagram showing temperature characteristics at the start of tapping.

[Explanation of symbols]

 1 Water temperature sensor 2 Hot water temperature sensor 3 Timer 4 Memory 5 Flow rate sensor 6 Microprocessor 11 Heat exchanger

Claims (1)

[Claims] 1. A water inlet temperature sensor and a hot water outlet temperature sensor which are provided on a water inlet side and a hot water outlet side of a heat exchanger in a water heater to detect a water inlet temperature and a hot water outlet temperature, respectively, and a hot water outlet time and a hot water outlet stop of the water heater. A timer that measures the hot water stop time until re-hot water, a memory that stores the number of the water heater that is being used, a flow rate sensor that measures the integrated flow rate of water entering from the start of hot water, the hot water time, the above Based on the hot water stop time and the number of symbols above, determine the integrated flow rate point at which an appropriate hot water temperature can be obtained, and feed forward based on the output of the water temperature sensor until the integrated flow rate from the start of hot water reaches the integrated flow rate point. After the control exceeds the integrated flow rate point, only feedback control based on the hot water temperature sensor or this feedback control And a hot water supply temperature control device including a microprocessor for performing the feedforward control.