JP3164712B2 - Circulating water heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention heats a heat exchanger connected to a water supply pipe and a hot water supply pipe by a heating section, and connects the end of the hot water supply pipe and the water supply pipe with a return pipe to form a circulation path. And
The present invention relates to a circulating hot water supply apparatus that performs circulating heating for operating a circulating pump provided in the circulating path and hot water supply with the circulating pump stopped.

[0002]

2. Description of the Related Art When controlling the heating amount of a heat exchanger at the time of hot water supply, a required heating amount is determined by executing an integral operation on a deviation between a detected temperature of hot water passing through a hot water supply pipe and a set temperature. The integrated value during hot water supply is stored as an optimal integral value, and at the beginning of the next hot water supply, the required heating amount is determined using the stored optimal integral value, and then the stored optimal integral value is used as an initial value for the calculation. A hot water supply device that determines a required heating amount is known.

In addition, the end of the hot water supply pipe connected to the heat exchanger and the water supply pipe are connected by a return pipe to form a circulation path, and a circulation pump provided in the circulation path is operated to perform circulation heating. There is also known a circulating hot water supply apparatus for supplying hot water by stopping a circulating pump.

[0004]

The above-described technique of storing an integral value for a temperature deviation as an optimal integral value and determining the necessary heating amount as an initial value for the next integral operation is described above. When applied to a circulating hot water supply apparatus, problems such as overshoot occurring at the time of hot water supply and rising at the time of circulating heating occur.

That is, during circulating heating, the difference between the hot water supply temperature and the hot water supply temperature is small, so that the thermal efficiency is reduced, and the optimum integral value at that time becomes large. Then, the required heating amount becomes excessive. Conversely, during hot water supply, the difference between the hot water temperature and the hot water temperature is large, so that the thermal efficiency is higher than during circulating heating, and the optimal integrated value at that time becomes smaller. If it is set to a value, the required heating amount is insufficient.

However, if the optimum integral value during circulating heating is used for controlling hot water supply, an overshoot occurs, and if the optimum integral value during hot water supply is used for controlling circulating heating, the start-up becomes slow.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. Even when the optimum integral value is determined as the initial value of the next integral operation and the necessary heating amount is determined, the overshoot at the time of hot water supply and the circulation heating It is an object of the present invention to obtain a circulation type hot water supply device capable of reliably preventing a delay in rising of a hot water.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a heat exchanger connected to a water supply pipe and a hot water supply pipe is heated by a heating unit.
The hot water supply pipe and the water supply pipe are connected by a return pipe to form a circulation path, and a circulation pump provided in the circulation path is operated to perform circulating heating or to stop and supply hot water. A feedback operation unit that performs at least an integral operation on a deviation between the detected temperature of the hot water passing through the heater and the set temperature, and determines whether or not circulation heating is being performed in the circulation type hot water supply device that controls the heating unit according to the output thereof A circulating heating determination unit, an optimum integration value storage unit for storing integration values of the feedback calculation unit during circulation heating and during hot water supply as optimum integration values, respectively, and an optimum integration value storage unit corresponding to the determination result of the circulation heating determination unit And selecting the optimum integral value instead of the output of the feedback calculation unit until a predetermined time has elapsed from the start of hot water supply or circulation heating. It is obtained by a optimum integration value control unit to provide control to.

Preferably, the optimum integral value control unit sets the output of the feedback calculation unit after a predetermined time has elapsed from the start of hot water supply or circulation heating as an optimum integral value in accordance with the result of the judgment by the circulation heating judgment unit. The learning is stored in the optimum integration value storage unit.

[0010]

According to the present invention, the integrated value of the feedback calculation section is stored as the optimum integrated value separately for the circulation heating and the hot water supply, and the optimum integrated value corresponding to the next control is selected, and from the start of the control. Since it is used as a calculated value of the feedback calculating unit until a predetermined time has elapsed, it is possible to reliably prevent an overshoot during hot water supply and a delay in rising during circulating heating.

In this case, the output of the feedback calculation unit after a lapse of a predetermined time from the start of the control is stored as an optimum integration value in correspondence with the result of the judgment by the circulation heating judgment unit, so that the optimum value to be used in the next and subsequent times is stored. The integrated value can be made more optimal.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 is a schematic configuration diagram of an embodiment of the present invention, which mainly includes a water heater main body 1, a hot water tap 6, and a control unit 10.
Consists of 0.

The water heater main body 1 includes a heat exchanger 4, a circulation pump 7, a gas burner 8, a proportional valve 10, and an on-off valve 11. The heat exchanger 4 is connected to the water supply pipe 2 and the hot water supply pipe 3. A hot water tap 6 is provided at the end of the hot water pipe 3.
Is connected to the water supply pipe 2 via the return pipe 5. Thus, a circulation path consisting of the water supply pipe 2 → the heat exchanger 4 → the hot water supply pipe 3 → the return pipe 5 → the water supply pipe 2 is formed. Return pipe 5
Circulating pump 7 for circulating hot and cold water in the circulation path
Is provided. The gas burner 8 is connected to a gas pipe 9, and a proportional valve 10 and an on-off valve 11 are provided in the gas pipe 9.

The control section 100 controls the proportional valve 10 and the on-off valve 11. For this purpose, a water flow switch 12 for detecting the water flow in the water supply pipe 2 on the upstream side as viewed from the connection point of the return pipe 5
And a water flow sensor 13 for detecting the flow rate Q of the water supply pipe 2 on the downstream side.
Further, a hot water temperature sensor 14 for detecting hot water temperature T _C and a hot water temperature sensor 15 for detecting hot water temperature T _M of hot water pipe 3 are provided. The control unit 100 controls the proportional valve 10 and the on-off valve 11 based on these detection signals and the set temperature T _S of the temperature setting unit 16 for setting the hot water supply temperature. Although the control unit 100 also controls the circulation pump 7, the control line is omitted since it is not directly related to the present invention.

FIG. 1 is a block diagram showing a detailed configuration of the control unit 100. In the figure, the circulation heating determining unit 21 outputs a circulating signal when the flow rate Q is detected by the water amount sensor 13 and the water flow switch 12 is in an off state in which the water flow is not detected, and the subtractor 22 outputs the set temperature T _S. Feed water temperature T
_The feedforward calculation unit 23 calculates the deviation of the feedforward control amount FF based on the deviation and the flow rate Q.
Is calculated. The combustion necessity determination unit 24 determines whether or not combustion is necessary based on the flow rate Q and the feedforward control amount FF. Specifically, the flow rate Q is equal to or greater than the ignition flow rate and the feedforward control amount FF When is equal to or greater than the ignition value, a combustion request signal is output, and the timer 25 starts operating in accordance with the combustion request signal, and closes the switch 27 after a lapse of a set time. Subtractor 26
Calculates the difference between the hot water supply temperature T _{M and} the set temperature T _S , and the difference is supplied to the feedback calculation unit 30 via the switch 27. The optimum integration value storage unit 28 stores the circulation heating storage value X and the hot water supply value storage value Y separately, and the optimum integration value control unit 29 controls writing and reading of these storage values. . The feedback operation unit 30 includes a well-known proportional element 31, a differential element 32, and an integral element.
33, the output of each element is added to obtain the feedback control amount FB. The temperature coincidence judging section 41 detects coincidence between the set temperature T _S and the hot water supply temperature T _M, and the timer 42 starts operating in accordance with the coincidence signal. Give to 29. In addition, in response to the time-up signal, the optimal integral value control unit 29 stores the integral value at that time as the optimal integral value in the optimal integral value storage unit 28. The heat amount determining unit 43 determines the heating amount based on the feedback control amount FB and the feedforward control amount FF, and the on-off valve driving unit 51 included in the heating unit 50 intermittently controls the on-off valve 11 according to the heating amount. The proportional valve driving section 52 controls the proportional valve 10 according to the heating amount.

The operation of the embodiment constructed as described above will be described below. The circulation pump 7 is stopped when hot water is supplied to open the hot water tap 6, and the circulation pump 7 is driven during circulation heating. The control unit 100 determines whether the hot water supply or the circulation heating is being performed based on the output signals of the water flow switch 12 and the water flow rate sensor 13, and determines the water flow rate sensor 13, the water supply temperature sensor 14, and the hot water temperature sensor, respectively.
The required heating amount is determined based on output signals from the temperature setting unit 15 and the temperature setting unit 16, and the proportional valve 10 and the on-off valve 11 are controlled.

In this case, the circulation heating determining unit 21 is provided with a water amount sensor.
When the flow rate Q is detected by 13 and the water flow switch 12 is in an off state in which the water flow is not detected, a circulating signal is output. When the circulating signal is output, the optimal integral value control unit 29 adds the circulating heating storage value X stored in the optimal integral value storage unit 28 to the feedback operation unit 30 and supplies the hot water supply value when the circulating signal is not output. The stored value Y is added to the feedback calculation unit 30. The feedback calculation unit 30 adds these stored values to the heat quantity determination unit 43 as the feedback control amount FB. On the other hand, the feed-forward calculation unit 23 deviations between the feed water temperature T _C and the set temperature T _S detected, and calculates a feedforward control amount FF based on the detected flow Q is added to the amount of heat determiner 43. The calorie determining unit 43 calculates the required heating amount from these control amounts. The on-off valve driving unit 51 intermittently controls the on-off valve 11 according to the required heating amount, and the proportional valve driving unit 52 controls the proportional valve 10.

When the flow rate Q is equal to or greater than the ignition flow rate and the feedforward control amount FF is equal to or greater than the ignition value, the combustion necessity determining unit 24 outputs a combustion request signal and activates the timer 25. When a time-up signal is output after the set time of the timer 25 has elapsed, that is, when a predetermined time has elapsed from the start of the control, the switch 27 is closed, and the deviation of the hot water supply temperature T _{M from} the set temperature T _S. The minute is added to the feedback calculation unit 30. The feedback calculation unit 30 calculates the feedback control amount FB by PID calculation according to the deviation and supplies the feedback control amount FB to the heat amount determination unit 43.

During the control of the heating amount, the temperature coincidence judging section 41
As a result, the coincidence between hot water supply temperature T _M and set temperature T _S is detected, and timer 42 operates while the coincidence signal is continuously output. If there is no match signal before the set time of the timer 42 elapses, the timer 42 is reset. Thus, the hot water supply temperature T _M and the set temperature T
_When the coincidence state with _S continues, a time-up signal is applied to the optimum integral value control unit 29. The optimum integration value control unit 29 updates the storage value of the optimum integration value storage unit 28 using the output of the feedback operation unit 30 at this time as the optimum integration value. In other words, if during circulating heating, the stored value X during circulating heating is updated,
If hot water is being supplied, hot water value storage value Y is updated. As a result, learning and storage of the optimum integral value are performed.

FIG. 3 is a flowchart showing a processing procedure when a microcomputer is used for the control unit 100 and the control unit 100 has the function shown in FIG. Hereinafter, according to this flowchart, neither circulating heating nor hot water supply is performed.
The control operation from the standby state will be described.

First, in step 101, it is determined whether or not combustion is possible, based on whether or not a condition that the flow rate Q is equal to or greater than the ignition flow rate and the feedforward control amount FF is equal to or greater than the ignition value is satisfied. If not possible, terminate the process,
If the combustion is possible, the process proceeds to step 102. Appropriate values are used for the ignition flow rate and the ignition value depending on whether hot water is being supplied or circulation heating is being performed. Then, in step 102, a timer for determining whether or not the control is in the initial stage is started.

In step 103, it is determined whether or not circulation is in progress, based on whether or not a condition that the flow rate Q is detected and the water flow is not detected is satisfied.
At 4, the stored value during circulation heating X stored in the optimum integrated value storage unit 28 is used as the feedback control amount FB. If the hot water is not being circulated, the optimum integrated value is set as the feedback control amount FB at step 105. The stored hot water value Y stored in the storage unit 28 is used.

In step 106, the feedforward control amount FF is calculated. In the following step 107, the required heating amount is calculated based on the feedforward control amount FF and the feedback control amount FB. In step 108, the required heating amount is calculated. The proportional valve is controlled, and the on-off valve is intermittently controlled.

Next, in step 109, it is determined whether or not the initial time of the control has elapsed based on whether or not the timer outputs the time-up signal. If not, the processing in steps 106 to 109 is performed. Is repeated, and the process proceeds to step 110 and the subsequent steps after the lapse of time.

In step 110, using the stored feedback control amount FB as an initial value, a PID calculation is performed on the deviation between the hot water supply temperature T _M and the set temperature T _S to calculate the feedback control amount FB. In step 111, the feedforward control amount FF is calculated. In step 112, the required heating amount is calculated based on the feedforward control amount FF and the feedback control amount FB. In step 113, the proportional valve is controlled in accordance with the required heating amount, and the on-off valve is intermittently controlled.

Next, in step 114, it is determined whether or not the operation is possible, based on whether or not a condition that the flow rate Q is equal to or greater than the ignition flow rate and the feedforward control amount FF is equal to or greater than the ignition value is satisfied. If the vehicle is not operable, the process ends. If the vehicle is operable, the process of the learning storage routine from step 115 is performed.

In step 115, it is determined whether or not the hot water supply temperature T _M matches the set temperature T _S. If they match, in step 116, it is determined whether or not the constant temperature state has continued for a predetermined time or more. It is determined whether or not the timer for checking is operating. If not, the timer is operated in step 117 and the process proceeds to step 118.

In step 118, it is determined whether or not the timer outputs a time-up signal. If the timer does not output a time-up signal, the process returns to step 115 and the subsequent steps. Move on to processing.

In step 119, it is determined whether or not circulation is being performed, based on whether or not a condition that the flow rate Q is detected and the water flow is not detected is satisfied.
The stored value X at the time of circulation heating stored at 0 is replaced with the current feedback control amount FB. If the hot water is not being circulated, the hot water supply value stored value Y is replaced at step 121 with the current feedback control amount FB. Return to step 110.

By the above processing, the control shown by the functional block in FIG. 1 can be realized, whereby the overshoot at the time of hot water supply and the delay of the rise at the time of circulating heating can be reliably prevented. The optimal integration value used in the next and subsequent times can be made more optimal.

In the above-described embodiment, the feedback operation unit having the operation elements of proportional, integral, and differential is used. However, the present invention is not limited to this, and at least the integral operation is performed. If so, almost the same operation as described above can be performed.

[0032]

As is apparent from the above description, even when the required heating amount is determined using the optimum integral value as the initial value of the next integral calculation, the overshoot at the time of hot water supply and the delay of the rise at the time of circulation heating are surely ensured. Can be prevented.

Further, the output of the feedback calculation unit after a predetermined time has elapsed from the start of the control is stored as an optimum integration value in accordance with the result of the determination by the circulation heating determination unit. The value can be more optimal.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a detailed configuration of main elements of an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of one embodiment of the present invention.

FIG. 3 is a flowchart for explaining the operation of the main element of one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hot-water heater main body 2 Water supply pipe 3 Hot-water supply pipe 4 Heat exchanger 5 Return pipe 6 Hot-water tap 7 Circulation pump 8 Gas burner 10 Proportional valve 11 Open / close valve 21 Circulation heating judgment part 23 Feed forward operation part 24 Combustion necessity judgment part 28 Optimum integration Value storage unit 29 Optimal integral value control unit 30 Feedback operation unit 100 Control unit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-159662 (JP, A) JP-A-63-83546 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F24H 1/10 302

Claims (2)

(57) [Claims] A heating unit heats a heat exchanger connected to a water supply pipe and a hot water supply pipe, and connects the hot water supply pipe and the water supply pipe with a return pipe to form a circulation path. In performing the circulating heating by operating the provided circulating pump or performing the hot water supply by stopping the circulating pump, at least an integral operation is performed on a deviation between a detected temperature of the hot water passing through the hot water supply pipe and a set temperature. A circulating hot water supply device for controlling the heating unit according to an output of the circulating heating water supply unit, wherein a circulating heating determining unit for determining whether or not circulating heating is being performed; An optimal integral value storage unit for storing the optimal integral value as an optimal integral value, and an optimal integral value of the optimal integral value storage unit corresponding to the determination result of the circulating heating determination unit, and selecting hot water supply or circulation. A circulating hot water supply, comprising: an optimal integral value control unit for providing the selected optimal integral value to control the heating unit in place of the output of the feedback operation unit until a predetermined time has elapsed from the start of heat. apparatus. 2. The optimum integration value control section outputs an output of the feedback calculation section after a predetermined time has elapsed from the start of hot water supply or circulation heating in accordance with a determination result of the circulation heating determination section. 2. The circulation type hot water supply apparatus according to claim 1, wherein the value is learned and stored in the optimal integration value storage unit.