JPH0271044A - Controller for hot water supplying apparatus - Google Patents

Abstract

PURPOSE:To supply hot water of set temperature immediately after the quantity of heat is varied when the quantity of heat is varied by providing integrating control means for correcting a deviation amount between outputting hot water temperature and the set temperature, and multiplying an integration correcting amount by the means by the variation ratio of the quantity of heat. CONSTITUTION:Difference (deviation amount) between a set temperature Ts set by a controller 44 and hot water temperature To detected by an output hot water temperature sensor 53 is corrected by an integration control with an integration correcting amount I, and an integration constant is so set to bXW that the variation amount of the amount I is proportional to water quantity W. The amount I is so set to the product of the variation ratio of a feed- forward amount FF as to vary in response to the variation of combustion amount (the quantity of heat). The calculation of the amount I is represented by an equation of In=In-1+bWn(Ts-To)FFn/FFn-1, where FFn is feed-forward amount calculated this time, FFn-1 is that calculated at a previous time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for a water heater that corrects the amount of deviation between a hot water outlet temperature and a set temperature by integral control.

[Prior Art] Some water heaters control heating Jit (for example, combustion amount) by a control device. The control of the combustion amount by the control device may be performed by combining feedforward control that determines the combustion amount based on the amount of water, set temperature, inlet water temperature, etc., and feedback control that corrects the combustion amount based on the result.

This feedback control may include integral control that corrects the amount of deviation between the set temperature and the tapped water temperature.

[Problem to be solved by the invention*1 On the other hand, the amount of correction obtained by integral control (integral correction M)
has a slow rate of change. For this reason, during hot water supply, the amount of water
When the inflowing water temperature, set temperature, etc. change and the combustion amount changes, the correction amount that had converged to an appropriate value before the change is still the correction amount after the change.

In other words, for a while after the combustion amount changes, the integral correction amount does not follow the change in the combustion amount, and hot water at the set temperature cannot be supplied.

The present invention has been made in view of the above circumstances, and its purpose is to provide a control bag W for a water heater that can supply hot water at a set temperature immediately after the heating amount changes. .

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a heating means 1 and a heat exchanger for exchanging heat generated by the heating means 1 with water, as shown in FIG. 2, and a control device 3 that performs heating control of the heating means 1. The technical means is to make the integral 11 positive amount by the control means 4 the product of the change ratio of the heating amount.

[Operations] In the present invention, the integral correction amount by the integral control means is the product of the change ratio of the heating amount of the heating stage A. Thereby, when the heating amount changes, the integral correction amount that converged to an appropriate amount before the change becomes the integral correction amount corresponding to the heating amount after the change.

In other words, the integral correction amount that has once converged before the change can be rationally re-evaluated after the change and used for the heating amount after the change.

[Effects of the Invention] According to the present invention, when the amount of heating changes, the integral correction 1Effi becomes appropriate immediately after the amount of heating changes, depending on the amount of heating after the change.

Therefore, when the amount of heating changes, the water heater to which the present invention is applied can supply hot water at the set temperature immediately after the amount of heating changes.

[Example] Next, an example in which the present invention is applied to a bypass mixing water heater will be described with reference to the drawings.

Figure 2 shows a schematic diagram of a bypass mixing type gas water heater.

This gas water heater is roughly divided into a combustion section 1 that burns fuel.
0, gas supply piping 20, water piping 30, and control device 4
It is composed of 0.

The combustion section 10 is a heating means of the present invention, and consists of a combustion case 12 in which a ceramic surface combustion type burner 11 is disposed, and a blower 13 that supplies air for combustion into the combustion case 12. Combustion case 12 by blower 13
After combustion, the combustion air guided inside is discharged as combustion gas from an exhaust port (not shown).

Gas supply piping? 0 is for supplying fuel gas to a nozzle 21 that opens on the inner circumference of a centrifugal fan 14 of a blower 13, and a main solenoid valve 22, a main solenoid valve 23, and a proportional valve 24 are sequentially provided from the upstream side. There is. The 1st flow of the proportional valve 24 is branched into two parts, one of which is provided with a switching solenoid valve 25 and the other with an orifice 26. The main solenoid valve 22, the main solenoid valve 23, and the switching solenoid valve 25 open and close the gas supply pipe 20 through energization control, and the opening ratio of the proportional valve 24 changes depending on the amount of energization.

This is to adjust the amount of gas supplied to the nozzle 21.

The water pipe 30 has one end connected to a water supply source and the other end connected to a hot water supply port, and exchanges heat between the heat generated by combustion of gas in the burner 11 and the water flowing inside. A heat exchanger 31 that heats the water to be heated, and this heat exchanger 3
1.

The water pipe 30 upstream of the branch path between the heat exchanger 31 and the bypass waterway 32 is equipped with a governor valve that keeps the amount of water flowing into the heat exchanger 31 and the bypass waterway 32 constant even if the water pressure flowing into the heat exchanger 31 and the bypass waterway 32 changes. Function and B of the water flow control valve that adjusts the water flow! An electric water flow control device 33 combined with A function is provided. In addition, the bypass waterway 32 includes a bypass waterway 32
In addition to adjusting the amount of water passing through the bypass waterway 32
A throttle valve 34 that can be opened and closed is provided.

Note that the throttle ratio of the electric water flow control device 33 is the same as that of the heat exchanger 31.
In order to regulate the total amount of water flowing into the bypass waterway 32, it is provided to be the same as the throttle valve 34 or smaller than the throttle valve 34. In addition, an electric water flow control device 33 and a throttle valve 34
uses a geared motor to drive a valve body that can open and close the waterway as a means to adjust the amount of water.

As shown in FIG. 3, the control device 40 is composed of a microcomputer 41, a relay circuit 42, and a drive circuit 43, and controls the burner 11 according to the outputs of a controller 44 and various sensors operated by the user. a sparker 45 that ignites, a main solenoid valve 22, a main solenoid valve 23, a proportional valve 24, a switching solenoid valve 25, an electric water one-way control device 33
, which controls the energization of the throttle valve 34.

Various sensors of the control device 40 are linked to a flame rod 46 and a thermocouple 47 for detecting the flame of the burner 11 and the air-fuel ratio, an electric water flow control device 33, and a valve body of the throttle valve 34 to detect the opening degree. potentiometers 48 and 49 for detecting air flow, and an air volume detection sensor 50 that detects the air volume of the blower 13 based on its rotational speed. An inlet water temperature sensor 51 that detects the temperature of water flowing into the heat exchanger 31 and the bypass waterway 32
, a hot water temperature sensor 5 that detects the temperature of hot water that has passed through the heat exchanger 31
2. A hot water temperature sensor 53 that passes through the heat exchanger 31 and the bypass waterway 32 and detects the temperature of the mixed hot water, and the heat exchanger 3
1 and a water amount detection sensor 54 that detects the amount of water flowing into the bypass waterway 32.

Note that the air volume detection sensor 50 includes a rotating body that is interlocked with the motor of the blower 13, and generates a pulse signal according to the rotation of the rotating body. Further, the water amount detection sensor 54 includes a rotating body that rotates with the flow of water, and generates a pulse signal according to the rotation of the rotating body.

Then, the computer 41 detects the rotational speed of the blower 13 and the rotational speed of the rotating body from the pulse signals generated by the airflow detection sensor 50 and the water flow rate detection sensor 54, and detects the airflow and water volume.

Next, combustion control and water amount control by the computer 41 will be briefly explained.

The user operates the switch connected to the hot water supply inlet, and the water pipe 3
When a water flow is generated at zero, the rotating body within the water amount detection sensor 54 rotates, and combustion is started. The amount of combustion after the start of combustion is determined by the amount of water obtained by various sensors, the temperature of water entering, the temperature of the hot water passing through the heat exchanger 31, the temperature of the mixing water, and the temperature of the mixing water so that the set temperature set by the controller 44 is obtained. The voltage of the blower 13 is controlled so that the blower 13 supplies the burner 11 with an air volume corresponding to the determined combustion amount.

- In other words, combustion 1 is equal to air blowing 1 from blower 13. Then, the proportional valve 24 and the switching solenoid valve 25 are controlled to be energized so that a gas amount corresponding to the rotational speed of the blower 13 and the temperature of the flame of the burner 11 is obtained. In addition, the amount of combustion is
The temperature of the hot water passing through the heat exchanger 31 is set to be maintained above a temperature (for example, 60° C.) at which water generated by combustion (drain water) does not adhere to the heat exchanger 31.

The throttle valve 34 is fixed at an appropriate opening calculated from the incoming water temperature, the set temperature, the temperature of the hot water that has passed through the heat exchanger 31, and the outlet temperature. Note that this fixation is set so that the amount of water flowing through the bypass waterway 32 is 21 times the amount of water flowing through the heat exchanger 31. In other words, the ratio of flow resistance between the bypass waterway 32 and the heat exchanger 31 is approximately 2:1 due to the throttle valve 34.
It is said that In addition, the opening degree of the throttle valve 34 is released when the amount of water entering is small or when the temperature of the hot water is to be lowered.
The throttle valve 34 is energized and controlled so as to have an opening degree calculated according to the amount of water entering and the temperature of hot water exiting.

Further, the electric water flow rate control device 33 is controlled to be energized so as not to exceed the maximum flow rate required to obtain the hot water temperature.

Next, the calculation of the combustion amount by the control bag 740 will be described in detail. Note that the integral correction means of the present invention is programmed into the microcomputer 41.

Combustion in this embodiment determined by the control device 40, iQ
is the sum of the feedforward iFr, the heat exchange capacity correction amount, the air-fuel ratio correction amount]゛, the proportional correction fIP, and the integral correction amount ■, and is expressed by the formula Q=FI'++T+P+I. be done.

In this way, by setting the combustion ff1Q to FT+KFT+P+I, the hot water temperature set by the user can be stably supplied.

The feedforward amount FF is determined by the difference between the set temperature Ts set by the controller 44 and the inlet water temperature Ti detected by the inlet water temperature sensor 51, the water xW detected by the water amount detection sensor 54, and the heat of the heat exchanger 31. Exchange efficiency 1/
eN.

This is expressed by the formula FF-(Ts-Ti) W/eff.

The heat exchange capacity correction amount includes the difference (deviation amount) between the set temperature Ts set by the controller 44 and the hot water outlet temperature ■0 detected by the hot water outlet temperature sensor 53, and the heat exchanger 31 used.
It is calculated from a heat capacity M that is preset according to the heat exchanger 31 and a constant a according to the bypass ratio of the heat exchanger 31 and the bypass waterway 32.

This is expressed by the formula K=a (Ts-ro)M.

Note that this calculation of the heat exchange capacity before the heat exchange capacity is performed by the controller 44.
Calculate the fictive temperature [0 of the heat exchanger 31 necessary to obtain the set temperature IS set by
The same thing is true when calculated from tM.

Note that this is expressed by the formula K=(Tc-Tm)M.

The air-fuel ratio correction N, ]' corrects the amount of gas increased or decreased by the air-fuel ratio correction, and has the sign of the correction 11N by the air-fuel ratio correction reversed.

This is expressed by the formula Tm-N.

The proportional correction amount p is calculated based on the difference (deviation amount) between the set temperature TS set by the controller 44 and the hot water temperature To detected by the outlet hot water temperature sensor 53, and the water iW detected by the water amount detection sensor 54. and the proportionality constant E.

This is expressed by the formula P = E (Ts - To) W. In this embodiment, E = 0.8 or later is appropriate.

The integral correction iI corrects the difference (deviation amount) between the set temperature Ts set by the controller 44 and the hot water temperature [0] detected by the hot water temperature sensor 53 by integral control.
Change in integral correction amount I] Let the integral constant be bxw so that the amount of water is proportional to the amount of water W. Also, the integral correction amount ■ is the combustion amount (
It is set as the product of the change ratio of the feedforward x1 so that it changes according to the change in the amount of heating (heating amount).

Then, the calculation of this integral complement i'EffiI is as follows: ei=1
．． −． 10bW,, (Ts~ro> FF,, /FFi.

It is expressed by the formula.

In addition, Iゎ is the integral correction amount calculated this time, Iゎ1 is the integrator]- amount calculated last time, F[, is the feedforward amount calculated this time, and IF, is the feedforward amount calculated last time. shows.

According to this embodiment, since the combustion amount Q (heating Jj□ and the feedforward IFI' are approximately proportional to each other, the integral correction amount ■ is determined by the change ratio (FFfi
/FF. -1). As a result, even if the combustion htQ changes due to a change in the inlet water temperature 11, a change in the water 1w, or a change in the set temperature]S during hot water supply (during combustion), the combustion amount before the change Q.

, the integral correction amount converged to ■. -1 is the combustion amount Q after the change
■ Integral correction amount according to ゎ. bawl.

In other words, the integral correction amount once converged before changing 1. .

1, it can be reasonably revalued and used after the change, and when the combustion amount Q changes, the combustion amount Q changes (immediately after the change, the appropriate value according to the combustion amount Q after the change) can be used. It is possible to add the integral correction amount I to the combustion amount Q. As a result, the bypass mixing water heater of this embodiment has a combustion ff1Q
Immediately after the change in temperature, the outlet temperature of 10 can be supplied as the set temperature.

(Modified example) Although an example has been shown in which the integral correction amount is the product of the change ratio of the feedforward amount, for example, in order to take into account the correct integral correction amount when the water amount changes, the change ratio of the water amount (W./ 'w,
-, ), or as the product of the ratio of change in the set temperature (S,/Ts.-1l), or as the product of the change ratio of the set temperature (S,/Ts.-1l), or as the product of the change in the set temperature ratio (Ti
, , /Tiゎ-I), or a combination of these may be used.

The present invention may be applied to integral control of PID control using differential control.

Although a water heater with a bypass waterway is shown as an example, the present invention may be applied to a water heater without a bypass waterway.

Further, although an example is shown in which gas is used as the fuel, other fuels such as kerosene may be used.

Further, although a combustion section that generates heat by burning fuel is used as a heating means, other heat generating means such as an electric heater may be used.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a schematic configuration diagram of a bypass mixing type gas water heater, and FIG. 3 is a schematic block diagram of a control device.

Claims (1)

[Scope of Claims] 1) A water heater comprising a heating means, a heat exchanger for exchanging heat generated by the heating means with water, and a control device for controlling heating of the heating means, comprising: The control device includes an integral control means for correcting a deviation amount between a hot water outlet temperature and a set temperature, and the integral correction amount by the integral control means is a product of a change ratio of a heating amount. Device.