JPH05340531A - Control device for hot water supply apparatus - Google Patents

Abstract

PURPOSE:To maintain feed hot water temp. at a prescribed value according to variations in the pressure and kind of gas by a method wherein fuel feed amount to be obtained based on prescribed temp., feed water temp. and hot water feed amount is corrected to control a fuel adjusting valve and air flow amount is adjusted by the fuel correction amount obtained by correction made based on the ratio of fuel feed amount to the corrected fuel feed amount. CONSTITUTION:A fuel feed amount G is calculated based on prescribed temp., feed water temp. and hot water feed amount and a fuel adjusting valve 3 is controlled based on a first fuel correction amount G0 obtained by correction made based on the control error of the prescribed temp. and feed hot water temp. The first fuel correction amount G0 is corrected based on the ratio of the fuel feed amount G to the first fuel correction amount G0 to calculate a second fuel correction amount and, based on the resulting second fuel correction amount and facter Kn (revolution number/gas amount), the revolution number of a combustion air fan 7 is adjusted. In this way the optimum ratio of combustion amount to air amount can be maintained even if the pressure and kind of gas vary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a momentary water heater.

[0002]

2. Description of the Related Art Conventionally, as described in JP-A-62-26416, in order to move a gas proportional valve in accordance with the response speed of a combustion air supply fan, a set temperature, a feed water temperature, Means for calculating the required heat amount based on the hot water supply temperature and water supply amount, means for setting the target opening of the gas proportional valve based on the required heat amount, combustion air supply fan detected by the target opening of the gas proportional valve and the air volume detection means The gas proportional valve is equipped with a means for outputting a proportional valve opening output signal to the proportional valve output circuit by adding the correction amount corresponding to the comparison result to the target proportional valve opening and comparing Based on the actual opening of the combustion air supply fan, that is, the opening that is corrected based on the actual rotation speed of the fan, rather than opening to the target opening that is set based on Gas of the instantaneous gas water heater Reiben control apparatus is known.

[0003]

According to the prior art, the amount of gas required to obtain the combustion amount F (the amount corresponding to the gas proportional valve opening) is F * Kff. When the gas actually used at home has a higher calorific value of combustion than the standard gas for water heater performance or the gas pressure is high, the gas amount G actually required to obtain the combustion amount F is F *.
Kff-ΔG. Here, Kff = gas amount / combustion amount. Further, since the actually supplied gas amount Go is adjusted on the basis of the deviation (Ts-Th) between the set temperature Ts and the hot water supply temperature Th, which fluctuates with time, as shown in FIG. It was stable at F * Kff-ΔG.

On the other hand, the fan rotational speed N is required to keep the ratio of the gas amount G and the air amount constant, and therefore the fan rotational speed N = Go * Kn.
Since it was calculated as (Kn = rotation number / gas amount), FIG.
As shown in (4), it fluctuates with time in synchronization with the actually supplied gas amount Go. Here, the fan rotation speed No when finally stabilized at Go = F * Kff−ΔG is: No = (F * Kff−ΔG) * Kn = F * Kff * Kn−ΔG * Kn = F * γ− ΔG * Kn, and as shown in FIG. 6, an appropriate rotational speed F * γ is ΔG *
It was below Kn. Here, γ is a ratio of the fan rotation speed N to the combustion amount F that does not cause incomplete combustion or reduction in combustion efficiency, and F * γ is an appropriate rotation speed with respect to the combustion amount F obtained by γ.

Therefore, the air amount becomes insufficient with respect to the combustion amount F, the combustion flame becomes smaller than that in the normal state, and incomplete combustion and combustion efficiency decrease may occur. Furthermore, the flame may flow back into the burner, and the burner may melt.

The present invention has been made in view of the above problems of the prior art. The object of the present invention is to cope with the type of gas and the pressure fluctuation, and incomplete combustion and reduction of combustion efficiency. An object of the present invention is to provide a controller for a hot water supply device that can maintain the hot water supply temperature at a set temperature without causing the above problem.

[0007]

SUMMARY OF THE INVENTION To solve the above problems, the present invention provides a fuel calculation unit for calculating a fuel supply amount based on a set temperature, a water supply temperature and a hot water supply amount, and a control deviation between the set temperature and the hot water supply temperature. A first correction unit that corrects the fuel supply amount based on the first fuel correction amount, a fuel adjustment unit that controls the fuel adjustment valve based on the first fuel correction amount, and a correction gain stored in advance. A second correction unit that corrects the first fuel correction amount based on the second fuel correction amount to calculate a second fuel correction amount; and an air amount adjustment unit that adjusts the air amount required for combustion based on the second fuel correction amount, A correction rate calculation unit that calculates a ratio of the fuel supply amount to the first fuel correction amount and a correction gain updating unit that stores the ratio as the correction gain are provided.

Further, the correction gain updating section stores the ratio as the correction gain when the ratio continues for a predetermined time while being kept constant. Further, the first correction unit includes an integral calculation unit and an integral value limiting unit, and the correction gain updating unit keeps the ratio constant when a predetermined time elapses while the control deviation between the set temperature and the hot water supply temperature remains zero. It is determined that it has continued for a predetermined time.

[0009]

When the actually used gas has a larger combustion heat generation amount or a higher gas pressure than the standard gas, the combustion amount and the air amount are kept in an optimum ratio in advance. In addition, the amount of air does not become excessive even if the gas has a small calorific value of combustion or the gas pressure is low.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 is a block diagram of a controller of a water heater according to the present invention, FIG. 2 is a flowchart showing an operation of a correction gain updating unit 10, FIG. 3 is a block diagram of a PID calculation unit 25, and FIG. 4 is a first correction unit 2. It is a block diagram which shows another Example.

As shown in FIG. 1, the control device for the gas water heater calculates the fuel (gas) supply amount G based on the temperature difference between the set temperature Ts and the water supply temperature Tc, the hot water supply amount Q, and the like.
And a first correction unit 2 that calculates the first fuel correction amount Go by correcting the fuel supply amount G based on the control deviation ΔTe between the set temperature Ts and the hot water supply temperature Th, and the fuel based on the first fuel correction amount Go. A fuel control unit 4 for controlling the control valve 3 and a first fuel correction amount Go based on the correction gain βe stored in advance in the correction gain output unit 5 to calculate a second fuel correction amount βe * Go. The air volume (fan) that adjusts the rotation speed of the combustion air supply fan 7 that supplies the air volume necessary for combustion based on the second correction unit 6 and the coefficient Kn (rotation speed / gas amount) and the second fuel correction amount βe * Go. A rotational speed) adjusting section 8; a correction rate calculating section 9 for calculating a ratio G / Go of the fuel supply amount G and the first fuel correction amount Go;
The correction gain output unit 5 with the ratio G / Go as the correction gain βe
And a modified gain updating unit 10 that stores the corrected gain.

Reference numeral 11 is a heat exchanger, 12 is a gas burner, 13 is a feed water temperature sensor for detecting the feed water temperature Tc, and 1 is a
Reference numeral 4 is a hot water supply temperature sensor that detects the hot water supply temperature Th, 15 is a flow rate sensor that detects the hot water supply amount Q, and 16 is a rotation speed / gas amount characteristic storage unit that stores a coefficient Kn.

The fuel calculation unit 1 is composed of a combustion amount calculation unit 20 and a gas amount calculation unit 21, and the coefficient Kff (is supplied to the gas amount calculation unit 21 via a gas group switching unit 22 and a gas amount / combustion amount characteristic storage unit 23. Gas amount / combustion amount) is entered. Therefore, the combustion amount F is calculated by the combustion amount calculation unit 20 based on the temperature difference between the set temperature Ts and the feed water temperature Tc and the hot water supply amount Q, and further, the combustion amount F is multiplied by the coefficient Kff by the gas amount calculation unit 21 to obtain the fuel. The (gas) supply amount G (Kff * F) is calculated.

The coefficient Kff is a value set by measuring the test gas at the time of shipment. Further, although it is possible to output the coefficient Kff according to the gas type by the gas group switching unit 22, even if the combustion heat generation amount and the gas pressure at the time of installation are different even in the same gas group, there is a difference in combustion efficiency. Control device is required.

The first correction section 2 is composed of a PID (proportional + integral + derivative) calculation section 25 and an addition section 26. Further, as shown in FIG. 2, the PID calculation unit 25 sets the set temperature T
s and the control deviation ΔTe of the hot water supply temperature Th, which outputs a signal proportional to the input, the integral calculation section 28 which outputs a signal that integrates the input which is the control deviation ΔTe, and the input which is the control deviation ΔTe A differential operation unit 29 that outputs a signal obtained by differentiating the output signal, an addition unit 30 that outputs a value obtained by adding the outputs of the operation units 27, 28, and 29, and a limiter unit 31 that limits the value of the output signal. It is multiplied by the gain Kfb.

The limiter unit 31 is provided so as not to perform overintegration when the control deviation ΔTe between the hot water supply temperature Th and the set temperature Ts continues, and ΔTe continues and the integral value is a predetermined limit value. When it exceeds, the output value is integrated and limited to the limiter value.

The correction gain updating unit 10 causes the correction gain output unit 5 to store the ratio G / Go as a correction gain βe when the ratio G / Go continues for a predetermined time while being constant. Further, a control deviation ΔTe between the set temperature Ts and the hot water supply temperature Th
When a predetermined time has elapsed with zero, the corrected gain updating unit 10 may determine that the ratio G / Go has remained constant for a predetermined time.

The operation of the hot water supply controller according to the present invention having the above-described structure will be described. First, the fuel calculation unit 1 determines the fuel supply amount G based on the temperature difference between the set temperature Ts and the water supply temperature Tc, the hot water supply amount Q, and the coefficient Kff by the gas group.

Further, in the first correction section 2, the output of the PID calculation section 25 in which the control deviation ΔTe between the set temperature Ts and the hot water supply temperature Th is input to the fuel supply amount G determined by the fuel calculation section 1 is added to the addition section 26. The first fuel correction amount Go added in step 3 is output. Then, the first fuel correction amount Go is input to the fuel adjusting section 4 to drive the fuel adjusting valve 3.

Further, in the second correction section 6, the fuel supply amount G
And the ratio G / Go of the first fuel correction amount Go to the correction gain βe, and the first fuel correction amount Go is multiplied to obtain the second fuel correction amount βe * G.
The value o is calculated and input to the fan rotation speed adjusting unit 8.

Next, the operation of the modified gain updating section 10 will be described with reference to the flowchart shown in FIG. First,
After the power is turned on, the corrected gain output section 5 is caused to output the initial value βe = 1 (S1). Next, it is determined whether or not combustion is in progress (S
2) If it is determined that combustion is in progress, it is further determined whether the set temperature Ts and the hot water supply temperature Th match (S3). On the other hand, if it is determined that combustion is not in progress, a predetermined time (for example, 20
The timer in which the second is set is initially activated (S4).

If it is determined in step S3 that the set temperature Ts and the hot water supply temperature Th match, it is then determined whether or not the timer has timed out (S5), and the set temperature Ts and the hot water supply temperature Th are equal to each other. If not, the timer is initialized (S4). If it is determined in step S5 that the timer has timed out, the correction gain output section 5 further stores the ratio G / Go between the fuel supply amount G and the first fuel correction amount Go as the correction gain βe (S6). If the timer has not timed out, the process returns to step S2.

FIG. 4 shows another embodiment of the first correction unit 2, in which the reciprocal 1 / G of the fuel supply amount G, the set temperature Ts, and the hot water supply temperature Th are input to the PID calculation unit 30 and are output to the output thereof. The coefficient 1 is added, and the calculation result is multiplied by the fuel supply amount G to obtain the first
The fuel correction amount Go is used. The first correction unit 2 is shown in FIG.
When the fuel supply amount G increases and βe * Go sharply increases, the output of the PID calculator 25 immediately increases and the value of the first fuel correction amount Go immediately increases. Since it changes, the ratio G / Go can be treated as the correction gain βe.

[0024]

As described above, according to the present invention, the combustion amount and the air amount are preliminarily kept at an optimum ratio even when the actually used gas has a large combustion heat generation amount or a gas pressure higher than that of the standard gas. Therefore, it is possible to prevent incomplete combustion and decrease in combustion efficiency due to insufficient air amount. Further, even if the amount of combustion heat of gas is small or the gas pressure is low, it is possible to prevent blowout of the combustion flame due to an excessive amount of air.

Further, when the ratio of the fuel supply amount to the first fuel correction amount remains constant for a predetermined time, this ratio is stored as the correction gain, so that the correction gain is not updated frequently. Therefore, the ratio of the gas amount to the air amount does not change frequently, and stable combustion can be realized.

Further, when the difference between the set temperature and the hot water supply temperature remains zero for a predetermined time, the ratio of the fuel supply amount to the first fuel correction amount is stored as a correction gain, and this ratio is multiplied by the first fuel correction amount. Since the second fuel correction amount is obtained by the above, it is possible to accurately obtain the second fuel correction amount without storing the ratio of the fuel supply amount to the first fuel correction amount, which is integration limited, as the correction gain.

[Brief description of drawings]

FIG. 1 is a block diagram of a controller for a water heater according to the present invention.

FIG. 2 is a flowchart showing the operation of a modified gain updating unit.

FIG. 3 is a block diagram of a PID calculator.

FIG. 4 is a block diagram showing another embodiment of the first correction unit.

FIG. 5 is a characteristic diagram showing a temporal change of a gas supply amount G with respect to a required gas amount (F * Kff) in a conventional technique.

FIG. 6 shows an appropriate fan speed (F *) in the prior art.
Characteristic diagram showing the temporal change of the fan rotation speed N with respect to γ)

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel calculation part, 2 ... 1st correction part, 3 ... Fuel control valve, 4
... Fuel adjusting unit, 5 ... Correction gain output unit, 6 ... Second correction unit, 7 ... Combustion air supply fan, 8 ... Air volume (fan rotation speed) adjusting unit, 9 ... Correction rate calculation unit, 10 ... Correction gain update Part, 11 ... Heat exchanger, 12 ... Gas burner, 13 ... Water supply temperature sensor, 14 ... Hot water supply temperature sensor, 15 ... Flow rate sensor,
16 ... Rotation speed / gas amount characteristic storage unit, 28 ... Integral calculation unit,
31 ... Limiter section (integral value limiting section), Ts ... Set temperature,
Th ... Hot water supply temperature, ΔTe ... Control deviation, Tc ... Water supply temperature, Q
… Hot water supply amount, G… Fuel supply amount, Go… First fuel correction amount, βe
... correction gain, Kn ... coefficient (rotation speed / gas amount).

Claims (3)

[Claims] 1. A fuel calculation unit that calculates a fuel supply amount based on a set temperature, a water supply temperature, and a hot water supply amount, and a fuel calculation unit that corrects the fuel supply amount based on a control deviation between the set temperature and the hot water supply temperature.
A first correction unit that calculates a fuel correction amount, a fuel control unit that controls a fuel control valve based on the first fuel correction amount, and the first fuel correction amount that is corrected based on a correction gain stored in advance. A second correction unit for calculating a second fuel correction amount, an air flow amount adjustment unit for adjusting an air flow amount required for combustion based on the second fuel correction amount, and a ratio of the fuel supply amount to the first fuel correction amount. A controller for a water heater, comprising: a correction rate calculation unit for calculating the correction ratio and a correction gain update unit for storing the ratio as the correction gain. 2. The water heater control device according to claim 1, wherein the correction gain updating unit stores the ratio as the correction gain when the ratio continues for a predetermined time while being kept constant. 3. The first correction section includes an integral calculation section and an integral value limiting section, and the corrected gain update section determines the ratio when the control deviation between the set temperature and the hot water supply temperature remains zero for a predetermined time. The water heater control device according to claim 2, wherein it is determined that the water temperature continues for a predetermined period of time.