JPH02219912A - Combustion control device for hot water supplier - Google Patents

Abstract

PURPOSE:To reduce the occurrence of an error in a heating amount due to the temperature change of fuel gas by a method wherein the temperature of fuel fed to a burner is estimated based on inflow water temperature information, and regulation of fuel is corrected based on the estimated temperature. CONSTITUTION:In a control device 30, a temperature control part 31 to perform control temperature based on a target temperature Tset has the function of each of a feedforward control part 32 and a feedback control part 33, and performs not only feedback control but also feedforward control based on a detecting temperature T of a feed hot water temperature thermistor 25. Since a thermistor serving as a temperature sensor to detect the temperature of water flowing to a heat exchanger is located in a water feed pipe, an inflow water temperature Tin for feedforward control is estimated by an inflow water temperature estimating part 34. A reference heating amount Qo is corrected by a temperature correcting part 35 according to a memory temperature, serving as the temperature of fuel gas, stored as the inflow water temperature Tin in a memory 34, to obtain a correcting heating amount Qr for the generation of which fuel gas substantially responding to a target temperature Tset can be fed.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention is a combustion type water heater that heats a heat exchanger for heating water using the combustion heat of a burner, in which the combustion amount of the burner is adjusted according to a target temperature. Regarding the combustion control device that controls the
In particular, it relates to improvements to reduce the effects of changes in the actual supply amount of fuel gas due to changes in temperature, etc.

[Prior Art] In a gas combustion type water heater, in order to heat water to a required temperature, for example, the temperature of water flowing into a heat exchanger (water inlet temperature) is
, the temperature of the water leaving the heat exchanger (outlet temperature), the water passing through the heat exchanger! 1. ．． The combustion amount of the burner is determined based on the detected information, and the amount of fuel gas supplied to the burner is adjusted by a proportional valve or the like according to the determined combustion amount.

[Problems to be Solved by the Invention] However, since the fuel gas supplied to the burner is a gas at room temperature, when the pressure is constant, the volume V varies according to the temperature t as follows: V=Vo (1+ t /273) ・・・
It changes as shown by (2) (here, ■o is the volume of gas at 0°C). That is, the density of the supplied fuel gas changes depending on the temperature, and the actual amount of fuel gas supplied changes depending on the temperature.

Therefore, in combustion equipment where the fuel supply amount is adjusted by a proportional valve that adjusts the volume or pressure of fuel gas,
Even if the proportional valve is controlled to supply a fixed amount,
The actual amount of fuel gas supplied changes depending on the temperature of the fuel gas.

Here, for example, the volume of fuel gas Vt at a temperature of 15°C
S and the volume of fuel gas at a temperature of 30°C.

When shown respectively, V+1=Vo (1←15/273)=■. +V,
x15/273... ■■,. =VO(t←
30/273) ;■. ＋■. X 30/273 ... (■) Therefore, the volume V0 of fuel gas at a temperature of 0°C is approximately % smaller than the volume of fuel gas (■15) at a temperature of 15°C, and the volume of fuel gas at a temperature of 15°C V ) 5
The volume of fuel gas ■3° at a temperature of 30°C is about 5% larger than that, so the actual amount of fuel gas supplied is:
When the temperature is 0°C, it is about 5% more than when the temperature is 15°C, and when the temperature is 30°C, it is about 5% more than when the temperature is 15°C.
will decrease.

Due to such a substantial change in the amount of fuel supplied, the burner cannot obtain the determined combustion amount, resulting in an insufficient amount of heating or an excessive amount of heating. As a result, the water passing through the heat exchanger is not given the amount of heat that corresponds to the target temperature, resulting in an excess or shortage of heat.

Normally, errors in the hot water temperature due to excess or deficiency in the amount of heat are corrected by a feedback control unit that detects the hot water temperature using a hot water temperature thermistor, so if a certain amount of time has passed after the start of hot water supply, the target temperature is reached. Although it is not the case that the temperature cannot be obtained, for example, the change in the outlet temperature due to the combustion control device based on the case where the temperature is 15°C is
℃, as shown in Figure 3, the target temperature TSE!t is heated to a temperature higher than the target temperature "i'set" and then the target temperature TSE!t is adjusted by correction of the feedback control.
On the other hand, if the temperature is 30°C, as shown at one point SaC in Figure 3, the temperature is once controlled to be lower than the target temperature 'i'set, and then the temperature deficiency is detected. After that, the heating amount is corrected and the target temperature 'I' is set.
calm down.

In this way, conventional combustion control devices that do not take into account the effect of the actual fuel supply amount have the problem of not being able to quickly supply hot water at the target temperature because it takes time to complete corrections using feedback control. be.

An object of the present invention is to provide a combustion control device in a water heater that can reduce errors in the amount of heating caused by changes in the temperature of fuel gas, and as a result, can quickly stabilize the temperature of hot water at a target temperature. purpose.

[Means for Solving the Problems] The present invention provides fuel 'A'N means for adjusting the amount of fuel supplied to a burner for heating water passing through the heat exchanger, at least the fuel 'A'N means flowing into the heat exchanger. A combustion control device for a water heater that performs control based on input water temperature information regarding the temperature of water, comprising a fuel temperature estimating means for estimating the temperature of fuel supplied to the burner based on the input water temperature information, and the fuel temperature estimation unit. and a fuel supply amount correction means for correcting the fuel adjustment means based on the estimated temperature estimated by the means.

[Effect 1] Normally, when the temperature of water entering the heat exchanger changes according to changes in the air temperature, etc., the temperature of the supplied fuel also changes according to the same tendency. That is, if the inlet water temperature is 1. When it goes up, it goes up; when it goes down, it goes down. In consideration of these trends, in the present invention, the fuel temperature is estimated based on inlet water temperature information regarding the temperature of water flowing into the heat exchanger, so that it is possible to estimate the fuel temperature that follows actual fuel temperature fluctuations. Can be done.

Since the fuel adjustment means that adjusts the fuel supply amount is adjusted based on the fuel temperature estimated in this way, the fuel supply 1 to the burner is not affected by changes in fuel temperature and the necessary combustion amount is maintained. Corrected to obtain.

Therefore, the water heated by combustion is given an amount of heat that is just the right amount for the target temperature, and is therefore quickly heated to the target temperature.

[Effects of the Invention] According to the present invention, an appropriate amount of fuel is supplied according to the target temperature without significantly changing the actual amount of fuel supplied due to a change in fuel temperature. The amount of combustion suitable for heating can be obtained.

Therefore, water is quickly heated to the target temperature throughout the year without being underheated or overheated. As a result, the hot water temperature can be quickly stabilized at the target temperature.

Embodiments] Next, a temperature control device for a water heater according to the present invention will be described based on embodiments shown in the drawings.

A burner group 11 including a plurality of burners is provided in a combustor case 10 of the gas combustion water heater 1 shown in FIG. A burner group 11 is located below the combustor case 10.
A blower 12 is provided for supplying combustion air to the combustion chamber. A water tube type heat exchanger 13 is provided above the burner group 11 in the combustor case 10, and water passing through the interior is heated by combustion heat from the burner group 11. A sparker 14 for igniting the burner group 11 and a flame rod 15 for detecting ignition of the burner group 11 are provided near the burner group 11 in the combustor case 10 . Furthermore, an exhaust port 2 is provided above the combustor case 10 for discharging combustion exhaust gas to the outside.

A nozzle pipe 16 for supplying fuel gas is provided below the burner group 11.
A plurality of fuel injection ports 16a for ejecting fuel gas are provided corresponding to each burner.

The fuel pipe 20 that guides the fuel gas to the nozzle pipe 16 has two solenoid valves 21 and 22 that allow the fuel gas to pass when energized.
! Governor proportional valves 23 that adjust the amount of fuel gas supplied by controlling the supply pressure in accordance with the current are provided from the upstream side to the source.

A water supply pipe 17 that leads water from a water supply source (not shown) to the heat exchanger 13 is equipped with an electric water flow control device 18 for adjusting the amount of hot water supply, and a flow lute for detecting the amount of water passing through the heat exchanger 13.
Sensors 19 are sequentially provided from the upstream side, and a hot water supply pipe 17a that guides hot water flowing out from the heat exchanger 13 to a hot water supply port (not shown) has a hot water outlet for detecting the outlet temperature Taut of hot water flowing out from the heat exchanger 13. A temperature thermistor 25 is provided.

The control device 30 has a control circuit centered on a microcomputer, starts and stops combustion in a predetermined sequence, and also controls the temperature of the hot water using the functional configuration shown in FIG.

In the control device 30, a temperature control section 31 for performing temperature control based on the target temperature "t'set" includes a feedforward control section (FFIII control section) 32 and a feedback control section (FB control section) 33. It has a functional section and performs not only feedback control based on the temperature T detected by the outlet hot water temperature thermistor 25, but also feedforward control.

Here, in order to simplify the WI construction of the water heater and simplify the manufacturing process, a thermistor as a temperature sensor for detecting the temperature of water entering the heat exchanger 13 is not provided in the water supply pipe 17. The inlet water temperature estimation unit 34 estimates the inlet water temperature Tin for feedforward control.

Here, when the flow rate sensor 19 detects the start of hot water supply, the detected temperature T detected by the outlet hot water temperature thermistor 25 changes! - is detected, and if the outlet temperature 'l'' out changes due to reheating or the like and there is a temperature gradient of the detected temperature T, the inlet water temperature Tin is not estimated.

If the temperature gradient of the detected temperature T is not detected when the first start of hot water supply is detected, the inlet water temperature Tin is estimated based on the detected temperature T of the outlet hot water temperature thermistor 25, and the estimated inlet water temperature Tin is The data is stored in the memory 34a to update the stored content.

The inlet water temperature Tin is estimated by comparing the detected temperature T of the outlet hot water temperature thermistor 25 with the memory temperature]'1ell already stored in the memory 34a, and the detected temperature T is determined as the memory temperature T.
If it is lower than lea, the detected temperature T is regarded as a new water entry temperature Tin, and the detected temperature T is stored in the memory 34a.

On the other hand, if the detected temperature 1゛ is higher than the memory temperature]'mem, there is a possibility that hot water will be reheated, so the memory temperature 'l'
Incorporating part of the temperature information of the detected temperature T into 1ell, a new water inlet temperature Tin is estimated, and it is stored as the memory temperature Tl1e.
11.

Here, the new water inlet temperature Tin is Tin= (aX't'el +bx'l') /
(a+b) −・・■ Part of the temperature information of the memory temperature T Well and the detected temperature T
It is calculated from a part of the temperature information.

The temperature control unit 31 detects the temperature 1 detected by the hot water temperature thermistor 25.
Until ゛ rises to a predetermined temperature lower than the target temperature 't''set] ゛a (for example, Ta = TSet-2), the FF control unit 32 performs feedforward control to control the target temperature TSet, water MW, and water inlet temperature Tin. The reference heating amount Q0 is determined based on the stored memory temperature 'l'1lel, and after the detected temperature 1' of the hot water temperature thermistor 25 reaches the predetermined temperature Ta, feedback control is performed by the FB control unit 33. Based on the target temperature TSet, the detected temperature T, and the water amount W, the reference heating amount Q0 is determined.

In this embodiment, this reference heating IQ is determined as a reference value based on the volume when the temperature 'rrue+ of the fuel gas is, for example, 15°C.

The temperature correction unit 35 corrects the reference heating amount Q0 according to the fuel gas temperature 'l'fuel in order to eliminate the influence of changes in the fuel supply amount due to changes in the temperature of the fuel gas.

Here, the change in the fuel gas temperature True, which fluctuates due to seasonal changes, is caused by the water inlet temperature Tin into the heat exchanger 13.
Taking advantage of the fact that it has the same tendency as the change in
Considering the memory temperature 1"lff1fJ as n as the fuel gas temperature Tftlel, the actual fuel supply amount (fuel gas quality M) can be calculated from the fuel gas volume (■) which changes depending on the temperature as expressed by the above equation (■). Calculate excess or deficiency,
The standard heating IQ is corrected accordingly, and the corrected heating amount Q
Determine r.

The drive unit 36 includes a temperature correction unit 3 that corrects the reference heating amount Q0.
The blower 12 and the governor proportional valve 23 are driven and controlled based on the corrected heating amount Qr of No. 5. Here, temperature correction section 3
A voltage based on the corrected heating lQr according to No. 5 is applied to the blower 12 to drive it, and the current value to the governor proportional valve 23 is controlled based on the detected rotational speed of the blower 12.

Furthermore, in order to prevent the water supply amount from exceeding the heating force, the control device 30 adjusts the opening degree of the electric water flow control device 18 based on the temperature detected by the outlet hot water temperature thermistor 25.
Limit the flow rate through.

Note that the controller 40, which allows the user to arbitrarily set the target temperature '1'Set, is installed according to the specifications of the water heater, and when the controller 40 is provided, the target temperature '1'Set can be set arbitrarily by the user. When the target temperature 'l'set is set and the controller 40 is not installed, a constant temperature (for example, 60° C.) is set as the target temperature set.

Next, combustion control in the gas combustion water heater 1 of this embodiment having the above configuration will be explained.

When a user opens a hot water tap (not shown) provided downstream of the hot water supply pipe 17a, water passes through the water supply pipe 17 and flows into the heat exchanger 13. At this time, the flow rate sensor 19 generates a pulse according to the amount of inflow water, and the gas combustion water heater 1
When a water amount W greater than the working water amount is detected and hot water supply is detected, ignition control is performed in a predetermined sequence and combustion is started.

In addition, it is detected whether or not there is a change in the temperature T detected by the hot water temperature thermistor 25, and the temperature detected by the hot water temperature thermistor 25]
If there is no change in ゛, the inlet water temperature T'in is estimated as a result of comparison with the stored temperature "I'1lte11" stored in the memory 34a according to the detected temperature T, and the stored temperature T1ell is updated. be done.

If there is a fluctuation in the detected temperature 1' of the outlet hot water temperature thermistor 25, the inlet water temperature Tin is estimated and the stored temperature "i'me"
m is not updated.

When the flame rod 15 detects the ignition of the ζ burner group 11, the temperature control section 31 performs temperature control.

Until the detected temperature T of the outlet hot water temperature thermistor 25 reaches the predetermined temperature Ta, the target temperature TSe is maintained by the controller 40.
! Feedforward control is performed in which the reference heating amount Qo is determined based on the storage temperature T icm of the memory 34a and the water 3tW measured by the flow rate sensor 19, and as a result of the heating,
After the detected temperature T reaches the predetermined temperature Ta, the target temperature'
+'set , a feedback control is performed in which the reference heating IQ is determined based on the detected temperature T.

In addition, the determined reference heating ff1Q is the water inlet temperature Ti
The stored temperature Tlea stored in the memory 34a as n is corrected by the temperature correction unit 35 by using the temperature Tftlel of the fuel gas, thereby obtaining corrected heating ff1Qr that can supply an amount of fuel gas substantially corresponding to the target temperature 1''set. It will be done.

Air blower 1! Since a12 and the governor proportional valve 23 are driven according to the corrected corrected heating amount Qr, from the beginning of temperature control control, they are driven according to the target temperature '+'set, regardless of the fuel gas temperature T fuel. The required amount of combustion can be obtained.

As a result, the outlet temperature TOut quickly stabilizes without deviating significantly from the target temperature Tset, as shown by the solid line A in Figure 3, and the time it takes to stabilize at the target temperature Tset is longer than in the conventional case. It will be faster.

As described above, according to this embodiment, since the fuel supply amount is corrected by using the temperature of the water flowing into the heat exchanger t\ as the temperature of the fuel gas, the temperature of the fuel gas Tf due to seasonal changes.
Since the necessary combustion amount can be obtained from the beginning of temperature control without being greatly affected by the uel, the broken line B in Fig. 3
, - Compared to the conventional system shown in the curve C, hot water can be rapidly and stably supplied to the target temperature TSet.

In addition, in this embodiment, in consideration of the fact that water heaters are used repeatedly on a daily basis, in seasons when the water temperature gradually decreases, the detected temperature T is set as the inlet water temperature Tin, and conversely, the water temperature increases In order to avoid confusion with reheating hot water during the season, only part of the temperature information of the detected temperature T is added to ensure that the incoming water temperature is adjusted gradually according to seasonal changes. Since it can be updated, appropriate incoming water temperature information is always provided when performing feedforward control.

In this embodiment, a control device that performs both feedforward control and feedback control is shown, but a control device that performs only feedforward control or feedback control can also perform similar control.

Although this embodiment shows the control device 5 for estimating the temperature of water flowing into the heat exchanger, it is equally effective for a water heater equipped with a water temperature sensor for detecting the temperature of water flowing into the heat exchanger. There is no need to explain.

[Brief explanation of the drawing]

Fig. 1 is a machine block diagram showing the functional configuration of a control device for a gas combustion water heater according to this embodiment, Fig. 2 is a schematic configuration diagram showing an outline of the gas combustion water heater according to this embodiment, and Fig. 3 The figure is a time chart showing changes in outlet temperature by the control device of this embodiment. In the figure, 23... Governor proportional valve (fuel adjustment means), 30
...control device (combustion control device), 35...temperature correction section (fuel temperature estimation means, fuel supply amount correction means). Figure 3 Time

Claims (1)

[Scope of Claims] 1) A fuel regulating means for regulating the amount of fuel supplied to a burner for heating water passing through a heat exchanger is configured to include at least incoming water temperature information regarding the temperature of water flowing into the heat exchanger. In the combustion control device for a water heater, the combustion control device controls the temperature of the fuel supplied to the burner based on the input water temperature information, and the estimated temperature estimated by the fuel temperature estimation means. A combustion control device for a water heater, comprising a fuel supply amount correction means for correcting the fuel adjustment means based on the fuel supply amount correction means.