JPS63105357A - Temperature control of hot water supplier - Google Patents

Abstract

PURPOSE:To shorten the reaching time and recovering time with respect to a set temperature by providing integration switch means prohibiting the integration computation of a feedback PID control until the hot water supply temperature reaches a predetermined region value of the set value, at the time of starting the hot water supply and an integration switch limiting timer limiting the integration computation prohibition. CONSTITUTION:Feedback PID control means 12 combines and sums up the computated output values of a proportion member P, an integration term I and differentiation term D so as to correct the quantity of deviation between a set temperature Ts and a supply hot water temperature To to obtain a feedback output value QB. A control operation quantity value obtained by combining a feedforward output value QF is imparted to a combustion adjustor, and the supply hot water temperature To is controlled to the set temperature To. The integration switch control means 12A is constituted such that it prohibits the integration term computation at the time of starting a hot water supply, and starts the integration computation at a point in time where the quantity of deviation TER has reached a predetermined region value Tk. However, when the supply hot water temperature has not reached a predetermined region of the set temperature, the integration computation prohibition is released by an integration switch limiting timer 14. Accordingly, the reaching time to the set temperature can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a temperature control device for a water heater that stabilizes the temperature of hot water.

2. Description of the Related Art Conventional temperature control devices of this type use a system that uses both feedforward control and feedback PID control. However, at the start of hot water dispensing, the ratio of feedback control becomes high and the temperature exceeds the set temperature. shade)
becomes large, making good temperature control difficult. As a means to solve these problems, control is performed using a feedforward output at the start of hot water dispensing, and a feedback output is synthesized after a predetermined period of time has elapsed. For example,
-18351 Publication 7'l11°A3゜Problems to be Solved by the Invention However, in the above configuration, when the feedforward output amount deviates from the appropriate amount.

There is a problem in that it takes a longer time to reach the set temperature, there is a risk that the set temperature will be exceeded, and it takes a longer time to stabilize at the set temperature.

The present invention solves these conventional problems.

The purpose is to shorten the time to reach the set temperature and the recovery time.

Means for Solving the Problems In order to solve the above-mentioned problems, the temperature control device of the present invention includes an integral switch that prohibits the integral calculation of feedback PID control at the start of hot water tap until the hot water tap temperature reaches a predetermined threshold value of the set value. It is equipped with a control means and an integral switch limit timer that limits prohibition of integral calculation.

Operation The present invention can eliminate the time delay in setting temperature due to feedforward output error with the above-described configuration.

Embodiment One embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a temperature control block diagram in one embodiment of the present invention, and FIG. 2 shows an outline of temperature control of a water heater.

In Fig. 2, 1 is a hot water tap and 2 is a heat exchanger.

3 is a burner that heats the heat exchanger 2; 4 is a proportional control valve that is a combustion amount regulator that adjusts the combustion amount of the burner 3;
5 detects the hot water supply amount QL with a flow rate sensor provided in the water supply channel 2 of the heat exchanger. 6 is the same feed water temperature sensor and heat exchanger 2
Detects the temperature Ti of water supplied to the Reference numeral 7 denotes the temperature sensor for the hot water outlet, which detects the temperature TO of the hot water heated by the heat exchanger 2.

8 is a temperature setting device for setting the hot water temperature to a desired temperature, and a set temperature T8 is set. 9 is a water heater controller including a hot water temperature control block shown in FIG.

Next, water temperature control will be explained using FIG.

11 is a feed forward control means, which controls the amount of hot water QI.

, the feed water temperature Ti and the set temperature Ts are input, and the heating amount QF is determined from the efficiency W using the following formula.

QF=QL(Ts-Ti)7w 12 is a feedback control means, which uses PID as a control law.
constitute rules. The feedback PID control means 12 synthesizes and sums the calculated output values of the proportional term P, the integral term (2), and the differential term in order to correct the deviation amount between the set temperature Ts and the tapped water temperature To to obtain a feedback output value QB. pv which is a combination of the feedforward output value OF and the feedback output value QB
A value, that is, a control operation amount value of PV=QF±QB is given to the combustion regulator 4, and the outlet hot water temperature To is controlled to the set temperature T3. 13 is a water heater. The control operation amount value pv is.

At the start of hot water supply, the amount of deviation T between the set temperature T$ and the outlet temperature 'ro
Since ER is large, the ratio of feedback PID output QB becomes high. The general PID control law is expressed by the following formula: PV=-TER+TD/r ・△TER+T/TIΣ
TER and Nashi are proportional constants, TD is a differential time constant, and TI
is the integration time constant and τ is the sampling time.

The integral switch control means 12A is configured to prohibit the integral term calculation in the above equation at the start of hot water dispensing, and to start the integral calculation when the deviation amount TER reaches a predetermined threshold value Tk (for example, within 5° C. of the set temperature). has been done.

However, if the feedforward output QF deviates from the optimum value and the outlet temperature does not reach the predetermined range of the set temperature, the integral switch limit timer 14 cancels the inhibition of integral calculation.

The integral switch limit timer 14 starts at the start of hot water dispensing, and sets the integral calculation prohibited state to the integral switch control means 12.
It is configured to be released by either the output of A or the output of the integral switch limit timer 14.

Figure 3 shows high temperature performance.

At the start of hot water dispensing, the integral switch limit timer IT starts at time to. Characteristic A is the case where the inhibition of integral calculation is canceled by the output of the integral switch control means 12A when the hot water outlet temperature To reaches the predetermined threshold value Tk, and characteristic B is the case when the hot water outlet temperature TO does not reach the predetermined threshold value Tk. , is released at time t1 by the output of the integral switch limit timer T.

In the above configuration, it is possible to reach the set temperature very easily.

Effects of the Invention As described above, the temperature control device of the present invention provides the following effects.

(1) Overshoot can be suppressed by providing a control means that prohibits the integral calculation of the feedback PID control until the tapping temperature reaches a predetermined threshold value of the set temperature at the start of tapping. In addition, by providing an integral switch limit timer, the time required to reach the set temperature can be shortened.

(2) Errors in the feedforward control amount can also be corrected, and feedforward control and feedback control can be optimized.

In addition, hot water temperature control performance is improved for repeated operations such as re-dispensing hot water.

[Brief explanation of the drawing]

FIG. 1 is a temperature control block diagram of a temperature control device for a water heater according to an embodiment of the present invention, FIG. 2 is a schematic diagram of temperature control of the water heater, and FIG. 3 is a hot water output performance diagram. 2...Heat exchanger, 3...Burner, 4.
... Combustion amount regulator, 5 ... Flow rate sensor,
6... Water supply temperature sensor, 7... Hot water temperature sensor, 8... Temperature setting device, 11...
- Feedforward control means, 12... Feedback PID control means, 12A... Integral switch control means, 14... Integral switch limit timer. Name of agent: Patent attorney Toshio Nakao and one other person? −
- Koga Volume 3 Figure 9 Force f

Claims (1)

[Claims] A heat exchanger, a burner that heats the heat exchanger, a combustion amount regulator that adjusts the combustion amount of the burner, a flow rate sensor, a water supply temperature sensor, and a hot water temperature sensor provided in a water supply channel of the heat exchanger. , a temperature setting device for setting a hot water temperature, and a feedforward control means for setting a combustion amount based on the amount of hot water detected by the flow rate sensor, the water supply temperature detected by the water supply temperature sensor, and the set temperature set by the temperature setting device. , a feedback PID control means for correcting the deviation amount between the tapping temperature and the set temperature; and a combustion regulator is energized by both output values of the control means, and an integral calculation of the feedback PID control means is performed at the start of hot water tapping. A temperature control device for a water heater, comprising an integral switch control means that prohibits integral calculation until the temperature reaches a predetermined threshold value of a set temperature, and an integral switch limit timer that restricts prohibition of integral calculation.