JPH02161255A - Heating control device for hot water supplying device - Google Patents

Abstract

PURPOSE:To delay the heating if the water temperature in the heat exchanger is high enough by determining the time interval between the moment when the water passes through the heat exchanger to the start of heating based on the temperature of water leaving the heat exchanger. CONSTITUTION:When the water flow is detected through a pulse signal from a water rate sensor 35, an ignition control section 41 computes the time interval up to the start of burning, i.e. the ignition delay time (t) based on the temperature Tex, detected by the use of a heat exchange thermistor 38, of water (hot water) leaving the heat exchanger 32 by t=(Tex-Tbase).h where Tbase is the baseline temperature to determine the delay time (t), and (h) is the coefficient. It then causes the ignition while the shutoff solenoid valve 21 and the main solenoid valve 22 are held opened when afore-said delay time (t) has elapsed. Therefore, if the heat exchanger 32 is being heated by the residual heat of the burning apparatus 10 such as burner plate 11, etc., a redundant heating will not be performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heating control device that controls a heating means in a water heater equipped with a woodwind heat exchanger, and particularly to a water heater that heats with a combustion device. Effective.

[Prior Art] In a water heater, for example, a gas water heater that uses a burner to heat water passing through a heat exchanger, a user operates a faucet provided at the downstream end of the heat exchanger to When water passes through the tank, it is detected by a water flow sensor or water flow switch, and combustion is started based on the water flow detection signal from the water flow sensor. Conversely, when the faucet is closed, combustion is stopped accordingly. Ru.

In addition, the amount of heating by the burner is determined by the set temperature of the controller (outlet hot water temperature setting device), which is set according to the user's wishes.
It is determined based on the temperature of the water entering the heat exchanger, the appearance of the water entering the heat exchanger, etc.
The combustion amount of the burner is controlled based on the determined heating amount.

[Problems to be Solved by the Invention] As described above, in a water heater in which combustion is controlled according to a water flow signal, water that stagnates in the heat exchanger due to the closing of the water faucet,
Even after heating operations such as combustion have stopped, it is heated by residual heat from burners, etc. (post-boiling).

This after-boiling tendency is particularly noticeable in combustion equipment in which a burner plate is disposed within the combustion chamber, because the temperature of the burner plate, flame-holding frame, etc. tends to rise.

For this reason, when a user uses a water heater again after once using it, water (hot water) heated by the residual heat of the burner, etc. remains in the heat exchanger, so when reusing it, When heating is performed again using a burner etc. in response to the water flow signal, the water in the heat exchanger will be heated further, and the temperature of the hot water that is supplied will be significantly higher than the set temperature. Depending on the temperature setting, this may cause great inconvenience to the user.

An object of the present invention is to eliminate such inconvenience when reusing a water heater and to provide a water heater that is easier to use.

[Means for Solving the Problems] The present invention provides a heating control device for a water heater that includes a water flow detection means for detecting water passing through a heat exchanger and controls a heating means for heating the heat exchanger. In the heating control device, the heating control device includes a temperature detection means for detecting the temperature of hot water flowing out from the heat exchanger, and the heating control device includes a temperature detection means for detecting the temperature of hot water flowing out from the heat exchanger, and a period from when water flow is detected by the water flow detection means until heating by the heating means is started. The technical means is to determine the time based on the temperature detected by the temperature sensing means.

The heat exchanger further includes water amount detection means for detecting the amount of water passing through the heat exchanger, and the temperature detection means measures the time from when the water flow is detected by the water flow detection means to when the heating means starts heating. It is more preferable to determine the temperature based on the detected temperature and the amount of water detected by the water amount detection means.

In the heating control device of the present invention, when water passes through the heat exchanger and is detected by the water flow detection means, the time until heating starts is determined based on the temperature detected by the temperature detection means. is determined, and heating of the heating means is started after the determined time has elapsed.

In addition, when water flow detection means is provided, when water flow is detected by the water flow detection means, the time until heating starts is determined based on the temperature detected by the temperature detection means and the temperature detected by the water flow detection means. is determined, and heating of the heating means is started after the determined time has elapsed.

[Effects of the Invention] In the present invention, the time from when water passes through the heat exchanger until the start of heating is determined based on the outflow temperature from the heat exchanger. Heating can be delayed if the temperature of the water (hot water) in the heat exchanger is high, such as when the water in the heat exchanger has already been heated by residual heat from the heat exchanger or the like.

Therefore, the temperature of the water (hot water) flowing out of the heat exchanger does not deviate significantly from the target temperature, and does not cause any major inconvenience to the user.

In addition, when equipped with a water amount detection means, the time until the start of heating is determined according to the outflow temperature from the heat exchanger and the amount of water passing through the heat exchanger. If the temperature of the heat exchanger does not drop immediately, the start of heating can be delayed sufficiently, and conversely, if a large amount of hot water is to be supplied, heating can be started quickly. Heating can be started in response to changes.

[Example 2] Next, the temperature control device for a water heater of the present invention will be described based on an example.

In the gas water heater schematically shown in FIG. 2, a combustor 10 includes a burner plate 11 disposed inside a combustor case 1 and a blower 12 that supplies combustion air. The blower 12 includes an impeller rotated by a motor in a scroll casing 12a, and when the blower 12 operates, combustion air is supplied from the scroll casing 12a to the burner case lla. The scroll casing 12a is provided with a nozzle 13 for ejecting fuel gas, and the combustor 10 performs all-primary air combustion in which combustion is performed using only the primary air supplied by the blower 1112, and the combustion gas is combusted from an exhaust port (not shown). It is discharged to the outside of the container case 1.

Inside the combustor case 1, near the burner plate 11,
A sparker 14 for spark discharge, a flame rod 15 for detecting flame, and a thermocouple 16 for detecting combustion temperature are provided.

The fuel pipe 20 that supplies fuel gas to the nozzle 13 includes, in order from the upstream side, a main solenoid valve 21, a main solenoid valve 22, and a governor proportional valve 2 that adjusts the downstream pressure of the fuel gas according to the current value.
3. Solenoid valves 24 for cutting off fuel gas are provided, and the upstream and downstream sides of the solenoid valves 24 are communicated through a fuel pipe 20 having an orifice 25. The orifice 25 is provided to improve throttling performance, and when the solenoid valve 24 is open, the orifice 25 limits the amount of fuel supplied instead of the nozzle 13, resulting in a small combustion amount.

The wood pipe 30 consists of a supply pipe 31 and a hot water supply pipe 31a connected to a water supply source and a hot water supply port (not shown), respectively, and a heat exchanger 32 and a bypass pipe 32a provided in communication between these. A part of the water supplied from 31 passes through the heat exchanger 32, and the rest passes through the bypass pipe 32a and is led to the hot water supply pipe 31a. A bypass valve 33 is provided at the confluence of the heat exchanger 32 and the bypass pipe 32a to adjust the ratio of water heated by the heat exchanger 32 to water directly guided through the bypass pipe 32a.

In the supply pipe 31, from the upstream side, a water flow control valve 34, a water flow sensor 35, an inlet water temperature thermistor 36, and a heat exchanger 32 are installed.
A heat exchange thermistor 37 for detecting the temperature of heated hot water is provided downstream of the hot water supply pipe 31a, and a hot water outlet temperature thermistor 38 is provided in the hot water supply pipe 31a.

The control device 40 is mainly a microcomputer (hereinafter referred to as "microcomputer"), and as shown in FIG.
It is composed of each functional part of the water flow control part 44, and further includes a controller 50 operated by the user and a safety circuit (not shown), each of which functions as follows.

When water flow is detected by the pulse signal from the water amount sensor 35, the ignition i'I11 control unit 41 controls the temperature TeX of the water (hot water) flowing out from the heat exchanger 32 detected by the heat exchange thermistor 37. Then, the time until combustion starts, that is, the time to delay ignition (delay time) t is calculated.

Here, when the temperature 't'ex is T LOW≦Tex≦TIIIGI, the delay time t is calculated based on this temperature Tex, for example, t = (Tex-'l''base) · h (here,
T base is the reference temperature for determining the delay time t,
h is a coefficient), and when the above delay time t has elapsed, both the original solenoid valve 21 and the main solenoid valve 22 are opened and ignition is performed.

Therefore, when the heat exchanger 32 is heated by the residual heat of the combustor 10 such as the burner plate 11, heating is not performed again.

As shown in FIG. 3, this delay time t is set to be longer depending on the temperature Tex detected by the heat exchange thermistor 37, and the higher the temperature is, and here the maximum value of the delay time t is set to about 5 seconds. are doing.

Therefore, after-boiling is prevented, and since the re-ignition is performed before the temperature of the heat exchanger 32 drops, the temperature of the hot water does not drop.

The ignition control unit 41 operates the blower 12 to perform a pre-purge in response to water flow detection, and operates the sparker 14 to perform spark discharge, and when the above-mentioned delay time t has elapsed, the original solenoid valve 21 and the main Ignition is performed by opening both solenoid valves 22.

When ignition occurs due to the ignition operation, it is detected by the flame rod 15, and after a predetermined period of time for the combustion state of the combustor 10 to stabilize after the ignition is detected, the combustion amount is controlled based on the set temperature and the like.

The temperature control unit 42 receives a temperature signal obtained from the resistance value of each thermistor arranged in the wood pipe 30, a pulse signal from the water amount sensor 35 generated according to the amount of water passing through the water pipe 30, and settings by the controller 50. Based on the temperature 'rset, the heat exchanger 32 determines the combustion amount Q required to heat the water to the target temperature.

Here, feedforward control (FF control) is performed until the outlet temperature 'out detected by the outlet hot water temperature thermistor 38 after the start of operation reaches a predetermined condition with respect to the set temperature 'l''set. When the hot water temperature Tout falls within a predetermined range with respect to the set temperature TSet, feedback control (FB control) is performed.

For FF control, the set temperature by the controller 50 is used.
t”set, inlet water temperature 'I'in detected by inlet water temperature thermistor 36, inlet water amount W detected by water amount sensor 35
, heat exchange rate 1/err, QFF('l”set
-T'in) xW/eff to calculate the required combustion amount QFF in FF control, and determine the combustion amount Q based on this required combustion amount QFF. - Also, for FB control, from the outlet hot water temperature 'rout detected by the outlet hot water temperature thermistor 38, the inlet water temperature 'I'in, and the inlet water amount W, q= ('l'out −Tin) xW, and the combustor 1
The actual heating iq of 0 is calculated, and the combustion amount Q is determined from the required combustion amount QFF and the heating amount q.

The combustion control section 43 controls the blower 12 and the governor proportional valve 23 based on the combustion amount Q obtained by the temperature control section 42 .

As for the control voltage to the blower 12, data corresponding to combustion and flQ are read out by arithmetic processing of a microcomputer according to the type of gas used, and the control voltage to the blower 12 is set according to the same combustion JiQ1 to Q2. For example, city gas (6C
), natural gas (13A), and propane gas (LPG) have different voltage ranges ■1 to ■2, ■3 to ■4, depending on the gas type, as shown by solid lines A, B, and C in Figure 4. ■5～V
A control voltage is applied at 6, and the motors are driven at different rotational speeds. In addition, at the time of ignition, points a, on solid lines A, B, and C for each gas type, corresponding to slow ignition combustion ILQa,
Voltage values Va and vb indicated by b and c.

Vc is applied, and the blower 12 is controlled to have slow ignition.

In addition, the current value to be applied to the governor proportional valve 23 is based on the detected rotational speed of the blower 12, and the corresponding data is read out by the arithmetic processing of the microcomputer according to the type of gas used. correspond to different rotational speeds N1 to N2, rotational speeds N3 to N4, and rotational speeds N5 to N6, respectively, as shown by solid lines E and F in FIG.
In order to obtain combustion 1iQ, different current values 11 to I2, current values I3 to I4, and current values I5 and I6 are respectively applied.

In addition, at the time of ignition, points d, e, in the solid line E, F for each gas type, corresponding to the slow ignition combustion amount Qa,
Current values 1d, Ie, If indicated by f are applied, and the governor proportional valve 23 is controlled to have a slow ignition.

Furthermore, in the combustion control, an error in the air-fuel ratio is determined based on the output voltage of the thermocouple 16 that is output according to the combustion temperature, and the voltage applied to the blower 12 is corrected based on the error.
By correcting the amount of combustion air supplied, an appropriate air-fuel ratio is maintained.

Furthermore, the current value to the governor proportional valve 23 is corrected in accordance with the rotational speed of the blower 12 that has changed due to the correction.

In water flow control, the water flow control unit 44 uses an inlet water temperature thermistor 3.
Based on the incoming water temperature detected by the heat exchanger 6, the opening degree of the bypass valve 33 and the opening degree of the fishery control valve 34 are adjusted to restrict the amount of water exceeding the heating capacity from flowing into the heat exchanger 32. Note that each opening degree is detected by a potentiometer (not shown).

The gas water heater of this embodiment having the above configuration operates as follows.

When the user sets the set temperature Tset using the controller 50 and turns on a faucet (not shown), water supplied through the supply pipe 31 is supplied to the water flow control valve 34 and the water flow sensor 35.
The water flows into the heat exchanger 32 and the bypass pipe 32a, the amount of each outflow is adjusted by the bypass valve 33, and flows out from the hot water supply port (not shown) via the hot water supply pipe 31a. When the passage of water in the supply pipe 31 is detected by the water amount sensor 35, the blower 12 starts rotating at a rotation speed controlled by slow ignition.

Further, ignition control is started based on a signal from the water amount sensor 35, and spark discharge is performed in the sparker 14. At the same time, the temperature of the water (hot water) flowing out from the heat exchanger 32]
The temperature Tex is detected by the heat exchange thermistor 37, and the delay time t is determined based on the temperature Tex. After this delay time t has elapsed, the original solenoid valve 21 and the main solenoid valve 22
is opened and the governor proportional valve 23 is energized with a predetermined slow ignition current value according to the gas type, fuel gas according to the slow ignition combustion amount Qa is ejected from the nozzle 13, and is mixed with combustion air. The mixture is mixed, ignited by the sparker 14, and ignited safely and reliably.

Therefore, for example, as shown in FIG. 6, if the water in the heat exchanger 32 is in a post-boiling state when hot water supply is once finished at time t1 and then started again at time t2,
Since the start of heating is delayed until 3 hours, the heat exchanger 32
The temperature Tex of hot water flowing out from the hot water supply pipe 31a and the temperature 'l'out of hot water flowing out from the hot water supply pipe 31a change only by increasing temperature due to post-boiling, as shown by solid lines H and I, respectively, indicating excessive heating of the water. Since this is not done, the temperature 'l''ex and the hot water temperature 'i
'out does not become abnormally high, so the user is not inconvenienced and can supply hot water with great peace of mind. Further, the delay time t is determined based on the temperature Tex, and since the ignition can be ignited before the outflow temperature Tex from the heat exchanger 32 decreases, the outlet temperature 'l'ou
t never decreases.

When ignition is detected by the flame rod 15, the FF control combustion 1QFF is calculated based on the signals from the controller 50, each sensor, and thermistor, and based on that, the air blower 8112 and the governor proportional valve 23 are controlled, and the combustion IQFF is calculated. Fuel gas is supplied accordingly.

After that, when the hot water outlet temperature Tout reaches a predetermined condition, feedback control is performed based on the hot water outlet temperature 't'out, and the actual heating amount q is determined based on the hot water outlet temperature 'r'out, etc., and the combustion JIQ in the feedback control is is determined.

As described above, in the gas water heater of this embodiment, the time until the start of heating is determined based on the outflow temperature from the heat exchanger, and heating is performed only after that time has elapsed. It does not become too expensive and can be used with confidence.

Next, a second embodiment of the present invention will be described.

In the second embodiment, the delay time is not determined only by the detected temperature Tex of the heat exchange thermistor 37 described above, but is determined according to the detected temperature '1' ex and the amount of water passing through the heat exchanger 32.

Here, when the temperature '1' eX is TLOW≦TeX≦Tlll0)I as in the above embodiment, the delay is determined based on this temperature 1''ex and the water amount W detected by the water amount sensor 35. The time t, for example, t 2g −< 1′ex−Tbase) 7w(′r
Base is the standard temperature and g is the coefficient).

As a result, as shown in Fig. 7, when the delay time t set for standard water 1 Wlid is shown as a solid line, when the maximum water JiWma A relatively short delay time t is set, and in the case of the minimum water amount Wa+in, a longer delay time t is set as shown by the solid line N.

Therefore, heating can be started in response to temperature changes in the heat exchanger, and the amount of water W passing through the heat exchanger 32 is large.
If the temperature of the heat exchanger 32 drops quickly, heating will be resumed in a short time, so the outlet temperature will drop <<, and the water volume W is small. Since the start of heating is delayed until the temperature of the heat exchanger 32 falls, excessively heated tap water will not flow out.

In each of the above embodiments, the delay time was determined based on the temperature difference between the temperature detected by the heat exchange thermistor and the reference temperature. Based on the temperature difference, the delay time may be determined according to the temperature difference, and the predetermined time (fixed time) is determined only when each temperature difference is a certain value or more.
It may be delayed.

In the above embodiments, the water flow sensor is used as the water flow detection means, but a water flow switch may also be used.

In the above embodiment, a gas water heater is shown, but the heating source is not limited to a combustion device using gas, oil, etc., and may be an electric heating source.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram showing the functional configuration of a control device for a gas water heater according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing the configuration of a gas water heater according to this embodiment, and FIG. A characteristic diagram showing the relationship between the detected temperature of the heat exchange thermistor and the delay time in this example, and FIG. FIG. 5 is a characteristic diagram showing the relationship between the rotation speed of the blower and the current of the proportional valve. FIG. 6 is a time chart for explaining the heating state in the present invention. FIG. 7 is a characteristic diagram showing the relationship between the rotation speed of the blower and the current of the proportional valve. It is a characteristic diagram which shows the relationship between the detection temperature of the heat exchange thermistor and delay time in 2nd Example of 2 according to each water amount. In the figure, 35...Water flow sensor (water flow detection means, water flow detection means), 37...Heat exchange thermistor (temperature detection means)
, 40...control device (heating control device).

Claims (1)

[Scope of Claims] 1) A heating control device for a water heater that includes a water flow detection means for detecting water passing through a heat exchanger and controls a heating means for heating the heat exchanger, wherein the heating control device The apparatus includes a temperature detection means for detecting the temperature of hot water flowing out from the heat exchanger, and the time from when water flow is detected by the water flow detection means until the heating means starts heating is determined by the temperature. A heating control device for a water heater, characterized in that the determination is made based on the temperature detected by a detection means. 2) The heating control device includes a water amount detection means for detecting the amount of water passing through the heat exchanger, and the time period from when water flow is detected by the water flow detection means to when the heating means starts heating. 2. The heating control device for a water heater according to claim 1, wherein the determination is made based on the temperature detected by the temperature detection means and the amount of water detected by the water amount detection means.