JPH06265206A - Temperature control device for hot water feeder - Google Patents

Abstract

PURPOSE:To improve a rising or a lowering of a hot water temperature at an initial time of hot water feeding in a hot water feeder in which a heating is controlled under a feed-forward control while assuring a stable state of fed-out hot water temperature. CONSTITUTION:In a system in which a distributor 11 for adjusting only a flow rate of a bypassing pipe 13 is controlled in response to a deviation between a hot water feeding-out temperature sensed by a hot water feeding-out temperature thermistor 19, its control is not carried out until the hot water temperature detected by the hot water feeding-out temperature thermistor 19 reaches a set temperature of -1 deg.C after detecting the starting of the hot water feeding, but it is carried out after the temperature reaches the set temperature of -1 deg.C. After starting of control once, the control is continued until a predetermined time (about 8 minutes) after detecting a stopped state of the hot water feeding elapses. Since the limiting of the water amount at a bypassing pipe 13 is not carried out at the initial time of the hot water feeding, a high heating amount corresponding to the amount of water can be attained and as the hot water feeding temperature is changed by changing an amount of water during the hot water feeding, the amount of water is changed by the distributor 11 and the set temperature is maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water heater having a bypass pipe in parallel with a heat exchanger, and adjusting the water amount in the bypass pipe only at the branch point between the heat exchanger and the bypass pipe. The present invention relates to a temperature control device for controlling the temperature.

[0002]

2. Description of the Related Art In a water heater, a bypass pipe is provided in parallel with a heat exchanger heated by a heating means such as a burner so that water passing through the heat exchanger side and water passing through the bypass pipe side can be separated from each other. Some of them are mixed to obtain a target hot water temperature. Also,
In this kind of water heater, in order to facilitate control of the hot water temperature, a bypass water amount controller (distributor) is provided to adjust only the water amount on the bypass pipe side while keeping the water amount on the heat exchanger side constant. By adjusting the amount of water on the side of the bypass pipe, there is a system in which the total amount of hot water supplied can be controlled, and at the same time, the hot water discharge temperature can be controlled. In this case, the heating amount of the burner or the like is determined as a feedforward control value based on the set temperature, the hot water supply amount, and the water supply temperature.
The amount of hot water supplied as the basis for determining the heating amount is not the amount of water only on the heat exchanger side, but the total amount of water including the amount of water on the bypass pipe side. Furthermore, the inventor of the present application, in the above water heater, changes the hot water temperature promptly when the set temperature is changed, and when the amount of water changes due to the change in the faucet opening, the fluctuation of the hot water temperature is reduced to provide a stable hot water temperature. In order to obtain it, we proposed a feedback control that detects the hot water temperature and increases or decreases the amount of water on the bypass pipe side according to the deviation between the hot water temperature and the set temperature.

[0003]

However, as described above, if the amount of water on the bypass pipe side is feedback-controlled based on the hot water temperature, during normal hot water supply (cold start) before hot water supply is not performed. Since the temperatures of the burner, the heat exchanger, etc. are low and the hot water discharge temperature in the initial stage of hot water supply is significantly lower than the set temperature, the amount of water supplied on the bypass pipe side is limited by the bypass water amount controller, and the amount of hot water supplied decreases. Therefore, the heating amount of the burner, etc. is controlled to a limited heating amount that is less than the maximum heating capacity of the burner, etc., based on the small amount of hot water supply with a limited amount of water in the bypass pipe. The amount becomes small and the rise of the temperature of the heat exchanger deteriorates. As a result, the hot water outlet temperature rises poorly even though there is excess heating capacity, and it takes time to obtain a sufficient amount of water commensurate with the heating capacity of the burner, etc. However, there is a problem in that it is not possible to obtain the water content and it takes time to set the amount of water, resulting in poor usability.

An object of the present invention is to provide a temperature control device for a water heater, which has a small fluctuation in hot water temperature and which is excellent in rising at the initial stage of hot water supply.

[0005]

According to the present invention, a heat exchanger heated by heating means and a bypass pipe are connected in parallel, and the amount of water passing through the bypass pipe at a branch point between the heat exchanger and the bypass pipe. In a water heater temperature control device having a water heating circuit provided with a bypass water amount controller for adjusting
When the water flow detection means for detecting water flow in the water heating circuit detects the water flow, the heating means performs heating, and the heating amount of the heating means is a set temperature, the water supply temperature to the water heating circuit, and the water heating circuit. Heating control means for controlling based on the amount of water supplied to the water, and a reference value calculation for calculating the maximum water amount reference value of the water heating circuit based on the deviation between the set temperature and the water supply temperature with respect to the maximum heating capacity of the heating means. Means and the water flow detection means detects water flow in the water heating circuit, and when the hot water discharge temperature is equal to or higher than a predetermined temperature set lower than the set temperature by a certain temperature, A correction value that starts the calculation of the water amount correction value proportional to the deviation from the hot water temperature of the water heating circuit, and ends the calculation of the water amount correction value after a predetermined time after the water flow detecting means detects the water flow stop. Calculating means and the base The technical means to and a water amount controlling means for controlling the water amount adjusting means based on a sum of the maximum water amount reference value value calculating means and said water amount correction value of the correction value calculating means.

[0006]

In the present invention, when hot water supply is started before normal hot water supply (cold start) and hot water supply is detected by the water flow detecting means, The heating by the heating means is started with the heating amount controlled based on the set temperature, the feed water temperature, and the feed water amount. At this time, the maximum water amount reference value of the water heating circuit is calculated by the reference value calculation means based on the deviation between the set temperature and the feed water temperature with respect to the maximum heating capacity of the heating means. The temperature is low because it is not heated, the hot water temperature is not sufficiently higher than the set temperature, and it does not reach the predetermined temperature set lower than the set temperature. The calculation of does not start. Therefore, the amount of water in the bypass pipe is controlled by the bypass water amount controller to the amount of water that corresponds only to the maximum water amount reference value, so the maximum amount of water according to the maximum heating capacity of the heating means passes through the water heating circuit. However, at this time, the heating amount of the heating means obtains the maximum heating capacity. Therefore, since the heat exchanger is heated by the maximum heating capacity of the heating means, a large amount of heat is given to the heat exchanger, the temperature of the water passing through the water heating circuit rises quickly, and the heating capacity is high. A sufficient amount of water can be obtained in accordance with the above, and rising of the hot water temperature does not delay.

Therefore, since the heating means performs heating with the maximum heating capacity from the start of heating, the amount of heat given to the heat exchanger increases, and as a result, the rising temperature of the hot water discharge is good and the amount of water at that time is high. A sufficient amount of water can be obtained without a significant decrease. When hot water supply continues, the temperature of the heat exchanger rises sufficiently, and along with that, the temperature of the water passing through the water heating circuit rises, and when the hot water temperature rises above a predetermined temperature, the amount of water by the correction value calculation means Calculation of the correction value is started. At this time, the tap water temperature is lower than the set temperature, and the water amount correction value becomes a negative value, so the amount of water passing through the water heating circuit decreases, and at this time, the tap water temperature has risen to a certain temperature difference with respect to the tap water temperature. The temperature quickly reaches the set temperature. In this case, the amount of water decreases temporarily, but since the temperature of the heat exchanger is sufficiently high, the deviation between the set temperature and the tap water temperature disappears shortly thereafter, and the water amount correction value changes from a negative value to 0. Therefore, the amount of tap water increases to the maximum amount of water according to the maximum heating capacity of the heating means calculated as the maximum water amount reference value.

When the user changes the opening degree of the faucet during hot water supply to change the hot water supply amount, the hot water outlet temperature temporarily changes, but the bypass water amount is changed by the calculated water amount correction value. Since the hot water is changed, the hot water temperature quickly returns to the set temperature, and a stable hot water temperature can be easily obtained without rapidly changing the heating amount. Similarly, when the set temperature is changed, the tap water temperature is quickly changed to the new set temperature because the bypass water amount is quickly changed by the water amount correction value, and at this time, the heating amount is largely changed. Since there is no need to do so, the tap water temperature does not become unstable.

On the other hand, once hot water is supplied and after the hot water temperature reaches a predetermined temperature which is lower than the set temperature by a certain temperature,
When the hot water supply is stopped, the correction value calculation means continuously calculates the water amount correction value regardless of the hot water outlet temperature until a predetermined time elapses after the hot water supply is stopped. At this time, since water flow in the water heating circuit is stopped, the outlet temperature may become higher than the set temperature due to the heat remaining in the heat exchanger in the water heating circuit, and the water amount correction value at that time is a positive value. Becomes When hot water is supplied again in this state, the bypass water amount adjuster operates to increase the amount of bypass water relative to the amount of water passing through the heat exchanger, so the hot water outlet temperature drops rapidly and overheating occurs. The generated hot water does not flow out.

After a lapse of a predetermined time after the hot water supply is stopped, the correction value calculating means finishes the calculation of the water amount correction value, and even if the hot water is reheated thereafter, the water amount controller keeps the maximum water amount reference value. Controlled only on the basis of. In this case, even if the heat remains only in a part of the water heating circuit and only the temperature near the outlet of the heat exchanger is slightly higher than the feed water temperature, sufficient time has elapsed after the heating was stopped. However, since it is insufficient to raise the temperature of the water passing through the water heating circuit, there is no problem at all, and conversely, since the water amount correction value due to the residual heat is not calculated, the rise is improved.

[0011]

According to the present invention, a bypass water amount controller for adjusting the amount of bypass water passing through the bypass pipe of the water heating circuit is used as a sum of the maximum water amount reference value of the reference value calculation means and the water amount correction value of the correction value calculation means. In addition, the water flow correction means detects the water flow in the water heating circuit and calculates the water amount correction value of the correction value calculation means, and the hot water outlet temperature is set lower than the set temperature by a predetermined temperature. Start in the above cases,
Since the calculation is completed a predetermined time after the water flow detection means detects the water flow stop, at cold start,
The heating means can perform heating with the maximum heating amount, and as a result, the outlet heated water temperature can be quickly raised without impairing the rise of the outlet heated water temperature. Also, during hot water supply, when the set temperature or the amount of hot water supply is changed, if the hot water outlet temperature fluctuates due to these changes,
Since the amount of bypass water is changed accordingly,
Fluctuations in the tapping temperature can be reduced, and a stable tapping temperature can be obtained.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on the embodiments shown in the drawings. FIG. 1 shows only a hot water supply unit 1 in a gas water heater with a reheating function. In FIG. 1, the water supply pipe 10 communicates with the heat exchanger 12 and the bypass pipe 13 via the distributor 11, and the downstream side of the heat exchanger 12 and the bypass pipe 13 join and are connected to the hot water outlet pipe 14. The water heating circuit of the present invention is configured as described above.

The distributor 11 is a water quantity controller for adjusting the water quantity of the heat exchanger 12 and the water quantity of the bypass pipe 13 in accordance with the turning angle of the valve body, and the turning angle and the water quantity of the heat exchanger 12 and As shown in FIG. 2, the relationship between the amount of water in the bypass pipe 13 and the total amount of water in the hot water outlet pipe 14 is 0 to 90 degrees, and only the amount of water in the heat exchanger 12 increases in accordance with the rotation angle. The amount of water is fixed to a very small amount of water (0.5 liters / minute) set to eliminate dead water in a nearly fully closed state.
From 90 to 270 degrees, the amount of water in the heat exchanger 12 is constant at 90 degrees, and only the amount of water in the bypass pipe 13 is set to increase according to the rotation angle. Here, the distributor 11 is driven by a stepping motor, and when a rotation angle corresponding to each water amount set as described above is given by calculation, it is driven by the number of steps corresponding to the rotation angle.

As a result, as shown in FIG. 3, the ratio of the amount of water in the heat exchanger 12 to the amount of water in the bypass pipe 13 (bypass ratio) is slightly reduced from 0 to 90 degrees depending on the angle, and 90 to 270 degrees. Then, it increases in proportion to the angle. In addition, 15 is a water amount sensor, 16 is a water supply temperature thermistor, 17
Is a water governor, 18 is a heat exchanger outlet thermistor, and 19 is a hot water outlet thermistor.

The heating means for heating the heat exchanger 12 is composed of two burners 22 and 23 in which the amount of fuel gas supplied by a proportional valve 21 provided in the fuel pipe 20 is controlled, and the fuel is also used. Each burner 22, 2 branches from the pipe 20.
The branch fuel pipes 24, 25 for supplying the fuel gas to the fuel cell 3 are provided with small solenoid valves 2 for controlling the combustion of the burners 22, 23, respectively.
6, 27 are provided. Reference numeral 28 is a blower for supplying combustion air, 29 is a main solenoid valve, 30 is an igniter ignition electrode, and 31 is a flame rod for ignition detection.

The hot water supply unit 1 having the above structure is controlled by the control device 40 together with the reheating unit (not shown).
The control device 40 controls the combustion of the burners 22 and 23 and the water amount control by the distributor 11, and controls the outlet heated water temperature by a combination of these controls.

In the combustion control, the point extinguishing control of the burners 22 and 23 is performed in response to the water flow detection by the water amount sensor 15, and the set temperature Tset by the remote controller (not shown), the water supply temperature Tin detected by the water supply temperature thermistor 16, and the water amount. The feedforward control amount of the heating amount of the burners 22 and 23 is calculated from the amount of water detected by the sensor 15 to control the opening and closing of the small solenoid valves 26 and 27, and the opening degree of the proportional valve 21 and the rotation of the blower 28. The combustion amount control for controlling the number is performed. After the outlet heated water temperature Tout reaches the set temperature Tset, the combustion amount control is performed by adding a part of the feedback control amount based on the outlet heated water temperature Tout to the feedforward control amount.

In the water amount control, a reference value calculation for calculating the maximum water amount reference value Lff by the set temperature Tset, the feed water temperature Tin, and the maximum heating capacity of the burners 22 and 23, and the set temperature Tset.
And the correction value calculation for calculating the water amount correction value Lp from the deviation of the outlet hot water temperature Tout, and the sum of the maximum water amount reference value Lff and the water amount correction value Lp calculated by these is set as the maximum water amount value L according to the water amount. The distributor 11 is controlled to a different rotation angle. The reference value is calculated by setting the amount of water in the water heating circuit to the set temperature T.
It determines the maximum water amount reference value Lff so as not to exceed the heating capacity for the set.

## EQU1 ## It is obtained by the arithmetic expression of Lff = (OPmax * a) / (Tset-Tin). (However, OPmax is burner 2
The maximum heating amount of 2, 23, a is a coefficient determined by the set temperature Tset.

The correction value calculation prevents the variation of the hot water outlet temperature when the user operates the faucet during hot water supply to change the amount of water, and improves the stability of the hot water outlet temperature when the set temperature is changed. The water amount correction value Lp is

## EQU00002 ## Lp = p1.times.Lff.times. (To-Tset) / (Tset-Tin) is calculated. (However, p1 is a constant term, and To is a value determined by To = Tout−temperature correction amount (° C.) depending on the tapping temperature Tout detected by the tapping temperature thermistor 19. Note that this equation 2 is Tset−Tin. ≧ 10
Used only at ° C. ) This correction value calculation is limited to the calculation of the water amount correction value Lp by the above-mentioned mathematical expression 2 in the transition period until the outlet heated water temperature reaches the set temperature in order to obtain the set temperature as quickly as possible at the cold start. The hot water temperature Tout is set to Tout
During <Tset −1, the water amount correction value Lp = 0 is set, and Tout is set.
At the time when ≧ Tset −1 is satisfied, the calculation of the water amount correction value Lp according to the above mathematical expression 2 is started. In addition, after the fire extinguishing operation due to water stoppage, the post-purge period until about 8 minutes has passed is
The water amount correction value Lp is continuously calculated by the equation 2, and after about 8 minutes, the water amount correction value Lp is set to 0 and the water amount control is performed.

The temperature correction amount in the above equation 2 is the result of the hot water temperature measurement test in the heat exchanger 12 in still water when the hot water outlet temperature Tout is set to an appropriate temperature only when all the following conditions are satisfied. As shown in FIG. 4, after 30 seconds after extinguishing the fire, the maximum correction amount calculated by the following mathematical formula 3 is used as the correction amount, and up to about 30 seconds after the fire extinguishing. Is obtained by proportionally distributing the maximum correction amount of Equation 3 with the extinguishing time as 0 according to the elapsed time. Condition extinguishing detection condition, condition post-purging (about 8 minutes after extinguishing), no change of set temperature after condition extinguishing, condition Tout> (Tset-Tin) x A + Tin (A = 0.0 to 1.0) To be.

## EQU00003 ## Maximum correction amount = (Tset-Tin) .times.C + D (where C = 1/40, D = 1.0)

In this embodiment, as described above, the calculation of the water amount correction value Lp is limited, but when the outlet water temperature Tout is lower than the set temperature Tset, the water amount correction value Lp component at the maximum water amount value L is used. After the maximum water amount value L is reduced and the water amount is limited, the maximum water amount value L increases as the hot water outlet temperature Tout rises, and there is a risk that a gradual increase in the water amount may occur. In order to prevent the gradual increase of the water volume and to obtain the stability of the water volume, the minimum value of the maximum water volume L is set according to the maximum water volume reference value Lff, as shown below, regardless of the calculated water volume correction value Lp. I try to limit it. L = 11 [liter / min] (in the case of L <11 <Lff) L = Lff [liter / min] (in the case of L <Lff <11) As a result, the maximum water amount value L becomes larger than the maximum water amount reference value Lff. It is possible to reduce the amount of hot water to be gradually increased.

In the present embodiment, by performing the combustion control and the water amount control as described above, the outlet heated water temperature Tout is uniquely determined with respect to the rotation angle of the distributor 11, as shown in FIG. In the above description, it is assumed that the faucet is opened so that a water amount equal to or larger than the maximum water amount value L calculated above flows out from the faucet, but the water amount flowing out from the faucet is the maximum. Even when the water amount L is less than
The outlet heated water temperature Tout corresponds to the rotation angle of the distributor 11.

Next, the operation of the hot water supply unit 1 of this embodiment will be described with reference to FIG. When the user opens the faucet and the amount of hot water supplied through the water heating circuit reaches the amount of ignition water (YES in step S1), the original solenoid valve 29 and the small solenoid valves 26, 27 are opened, and the proportional valve 21 is opened by the ignition opening. Controlled by burners 22, 2
3 is ignited, and heating control is started (step S
2). On the other hand, as the water amount control, the water supply temperature Tin detected by the water supply temperature thermistor 16, the set temperature Tset, the burner 2
The maximum water amount reference value Lff is calculated from the maximum heating capacities of 2 and 23. Hot water temperature Tout is set to the set temperature Tset by T
While the relation of out> Tset-1 ° C is satisfied, the water amount correction value Lp is not calculated by the equation 2, and the water amount correction value Lp is Lp.
= 0, and the distributor 11 is controlled with the maximum water amount reference value Lff as it is as the maximum water amount value L.

The outlet heated water temperature Tout rises, and Tout ≧ Tse
When it becomes a relation of t −1 ° C. (YE in step S3)
S), calculation of the water amount correction value Lp by the mathematical formula 2 is started (step S4), and thereafter, the distributor 11 determines the maximum water amount value L based on the sum of the calculated water amount correction value Lp and the maximum water amount reference value Lff. Controlled. Therefore, the hot water temperature Tout
However, when Tout = Tset −1 ° C., the amount of water in the bypass pipe 13 decreases, so the outlet heated water temperature Tout reaches the set temperature Tset, and thereafter, the amount of water gradually increases to the maximum water amount value L. During hot water supply, the set temperature Tset is changed, or the amount of water changes due to the operation of the faucet.
Even if t fluctuates, the rotation angle of the distributor 11 is immediately changed according to the temperature change, so that the fluctuation of the hot water outlet temperature Tout can be minimized and a stable hot water temperature can be obtained.

When the water faucet is closed and the amount of water becomes equal to or less than the amount of fire extinguishing water (YES in step S5), the combustion control ends, each solenoid valve is closed, and the combustion of the burners 2 and 23 is stopped (step S6). After that, the 8-minute timer starts to operate (step S7), and the post-purge in which only the blower 28 operates during the operation is performed for about 8 minutes. Formula 2
When the water amount correction value Lp is calculated by
While the minute timer is operating (N in step S8
O), the calculation of the water amount correction value Lp by Equation 2 is continuously performed, and when hot water is re-supplied during this period, the maximum water amount value L obtained by the sum of the water amount correction value Lp and the maximum water amount reference value Lff.
Based on the above, the distributor 11 is controlled.

When the timer for about 8 minutes is finished (YES in step S8), the post-purge by the blower 28 is finished. At this time, if the water amount correction value Lp is calculated by the equation 2, that The calculation operation also ends (step S9). Therefore, after that, when re-hot water supply is performed, the maximum water amount value L based only on the maximum water amount reference value Lff.
Since the distributor 11 is controlled based on the
The water amount of 3 is not limited based on the hot water outlet temperature Tout, and the water amount of the maximum water amount value L surely passes through the water heating circuit, and the heating control according to this water amount is performed. , 23 are not limited, and the heat exchanger 12 can be heated with a sufficiently large heating capacity.
As a result, the rise of heating is improved.

As described above, in the present embodiment, the water amount is maintained at the maximum water amount value L determined based on the maximum heating capacity of the burners 22 and 23, the set temperature Tset, and the feed water temperature Tin at the beginning of heating, Since it does not decrease, the combustion amount of the burners 22 and 23 can be maximized. Therefore, the amount of heat applied to the heat exchanger 12 in the initial stage of hot water supply becomes large, and as shown in FIG.
You can get hot and cold water.

[Brief description of drawings]

FIG. 1 is a partial schematic view showing a main part of a gas water heater with a reheating function according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship among a rotation angle of a distributor, a heat exchanger side water amount, a bypass pipe side water amount, and a total water amount in an embodiment of the present invention.

FIG. 3 is a characteristic diagram showing the relationship between the turning angle of the distributor and the amount of water on the bypass pipe side with respect to the amount of water on the heat exchanger side in the embodiment of the present invention.

FIG. 4 is a diagram for explaining a temperature correction amount used for calculating a water amount correction value Lp in the embodiment of the present invention.

FIG. 5 is a characteristic diagram showing the relationship between the turning angle of the distributor and the hot water outlet temperature in the embodiment of the present invention.

FIG. 6 is a flow chart for explaining the operation of the embodiment of the present invention.

FIG. 7 is a diagram for explaining the effect of the embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Hot water supply part (water heater) 11 Distributor (bypass water amount controller) 12 Heat exchanger 13 Bypass pipe 15 Water amount sensor (water flow detection means) 22, 23 Burner (heating means) 40 Control device (temperature control device, heating control) Means, reference value calculation means, correction value calculation means, water amount control means)

Claims (1)

[Claims] 1. A bypass water amount controller for connecting a heat exchanger heated by a heating means and a bypass pipe in parallel, and for adjusting a passing water amount of the bypass pipe at a branch point between the heat exchanger and the bypass pipe. In a temperature control device of a water heater having a water heating circuit provided, heating is performed by the heating means at the time of water flow detection of a water flow detection means for detecting water flow in the water heating circuit, and the heating amount of the heating means is set. Set temperature, water supply temperature to the water heating circuit, heating control means for controlling based on the amount of water supplied to the water heating circuit, based on the deviation between the set temperature and the water supply temperature with respect to the maximum heating capacity of the heating means And a reference value calculating means for calculating a maximum water amount reference value of the water heating circuit, the water flow detecting means detects water flow in the water heating circuit, and the hot water temperature is a constant temperature with respect to the set temperature. Is When the temperature is equal to or higher than the predetermined temperature set low, the calculation of the water amount correction value proportional to the deviation between the set temperature and the hot water temperature of the water heating circuit is started, and the water flow detecting means detects the water flow stop. Correction value calculation means for ending the calculation of the water quantity correction value after a predetermined time, and the water quantity based on the sum of the maximum water quantity reference value of the reference value calculation means and the water quantity correction value of the correction value calculation means. A water temperature control device, comprising: a water amount control device for controlling the adjusting device.