JP3033415B2 - Hot water supply control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot water supply control device for an instantaneous water heater having a bypass which bypasses a heat exchanger and mixing hot water from the heat exchanger and water from the bypass to supply hot water. It is.

[0002]

2. Description of the Related Art A conventional hot water supply control device of this type is shown in FIG.
As shown in, for example, JP-A-4-126951, a heating path 2 provided with a heat exchanger 1, a bypass path 3 bypassing the heat exchanger 1, and a flow ratio between the heating path 1 and the bypass path 3 , A feedwater temperature detector 5 provided upstream of the heating path 2, a heating temperature detector 6 provided in the heating path 2 downstream of the heat exchanger 1, and a heating temperature detector 6 provided in the heating path 2. To a flow rate detector 7, a mixing temperature detector 8 provided downstream of the junction of the heating path 2 and the bypass path 3, a tapping temperature setting device 9, a burner 10 for heating the heat exchanger 1, and a burner 10. During the hot water supply, the gas control valve 11 is driven according to the deviation of the signals from the tapping temperature setting device 9 and the mixing temperature detector 8 to control the mixing temperature to the set temperature. . On the other hand, based on the signals from the feedwater temperature detector 5 and the heating temperature detector 6, the opening degree of the flow dividing control valve 4 at which the drain generation preventing temperature (for example, 60 ° C.) in the heating path 2 is calculated and driven. When the hot water supply is stopped, the signals of the heating temperature detector 6 and the tapping temperature setting unit 9 are input to correct the hot water mixing ratio corresponding to the temporal change of the temperature, and the flow is adjusted so that the desired tapping stable temperature is reached in a short time. The opening of the valve 4 is set and driven.

[0003]

However, in the configuration of the above-described conventional hot water supply control device, during the hot water supply, the degree of opening of the branch flow control valve 4 is fixed to the degree of opening at which the drain generation preventing temperature in the heating path 2 is prevented, that is, a so-called feeder. Perform forward control,
Since the mixing temperature is controlled to the set temperature by the feedback control of the gas control valve 11 having a low response speed, it is not possible to cope with a rapid temperature change of the heating path 2 such as a post-boil or a pre-cooling at the time of re-hot water. In addition, the effects of after-boiling and pre-cooling were also proportional to the mixing temperature.

[0004] The degree of opening of the diversion adjusting valve 4 at the time of re-discharging is set by the detected temperature change of the tapping temperature setting device 9 and the heating temperature detector 6, but the diversion ratio is (set temperature-water supply temperature) / (Heating temperature-feed water temperature)
It cannot be determined just by changing the set temperature and heating temperature. In other words, in winter and summer, when the supply water temperature is different, the correction amount of the shunt adjusting valve 4 is different even with the same change in the heating temperature. That is, if the supply water temperature changes, the hot water temperature set immediately after the re-water supply cannot be obtained.

The present invention has been made to solve the above-mentioned problems, and has as its object to provide a quick and stable hot water supply.

[0006]

In order to achieve the above object, a hot water supply control device according to the present invention has the following configuration.

(1) A heating path connected to the tapping side of the heat exchanger, a bypass path bypassing the heat exchanger, a ratio adjusting valve for varying a flow rate ratio between the heating path and the bypass path, Water temperature detection means for detecting a temperature of water supplied to the heating path, heating detection means for detecting a heating temperature of the heating path downstream of a heat exchanger, and a junction between the heating path and the bypass path
Hot water detection means for detecting the downstream mixing temperature, temperature setting means for arbitrarily setting a set temperature , and a water amount to the heat exchanger.
Means for detecting the amount of water to be detected;
Storage means for storing the supply water temperature, first feedforward control means for setting an opening of the ratio adjusting valve according to the supply water temperature, the heating temperature, and the set temperature, and storage of the storage means. Value, the heating temperature, and the set temperature
The second valve for setting the opening of the ratio adjusting valve according to the
Feedforward control means, the set temperature and the mixing
Opening of the ratio adjustment valve to reduce the deviation from the temperature
Feedback control means for setting and detecting the water amount
The second feedforward control means for a predetermined time if
The ratio and the set value of the feedback control means are added to obtain the ratio.
Control drive of the rate adjusting valve, and after the predetermined time , setting of the first feedforward control means and the feedback control means.
A ratio controller for controlling and driving the ratio adjusting valve by adding a constant value .

[0008]

The present invention operates as follows by the above-mentioned structure.

(1) The opening of the ratio adjusting valve is set by the feedforward control means in accordance with the feed water temperature Tc, the heating temperature Th, and the set temperature Ts. For example, the required flow rate Vff of the heating path is obtained by the following equation, and the opening is set based on Vff.

Vff = (Ts−Tc) / (Th−Tc) Then, the ratio adjustment valve is driven based on the set opening of the feedforward control means. That is, the opening degree at which the mixing temperature reaches the set temperature when the hot water and the hot water in the bypass path are mixed can be set.

(2) The feedforward control means sets the opening in the same manner as (1). The feedback control means sets the opening of the ratio adjustment valve so as to reduce the deviation between the set temperature Ts and the mixing temperature Tm. For example, a known PID
An opening is determined to bring the deviation closer to zero by the operation.

When the hot water supply is started, the ratio adjusting valve is driven based on the sum of the set opening of the feedforward control means and the set opening of the feedback control means. That is, the basic opening is determined by the feedforward control means, and a deviation between the mixing temperature and the set temperature due to a response delay or an error of the detection means or the ratio adjusting valve is corrected by the feedback control means.

(3) The water supply temperature during hot water supply is stored from the storage means, and the opening degree of the ratio adjustment valve is similarly set using the stored value for the water supply temperature of the feedforward control means in (1).

(4) For a predetermined time immediately after the start of hot water supply, the proportional adjustment valve is controlled by an addition value of the set opening of the second feedforward control means and the feedback control means using the stored value of (5). After a predetermined time, the ratio regulating valve is controlled by the sum of the set opening degrees of the first feedforward control means and the feedback control means using the water supply temperature of the water temperature detection means.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, an inlet 13 and a heating path 14 are connected in series via a heat exchanger 12, and water is passed through the inlet 1
3, flows in the order of the heat exchanger 12 and the heating path 14. A bypass 15 bypassing the heat exchanger 12 is connected to a junction 16 of the water inlet 13 and a junction 17 at the tip of the heating path 14. At the junction 17, the flows of the heating path 14 and the bypass 15 are merged, and the hot water is discharged. It flows to road 18. Reference numeral 19 denotes a ratio adjusting valve provided in the middle of the bypass passage 15, which is a known solenoid-driven water amount proportional valve, adjusts the opening degree of the bypass passage 15 by an open / close signal, and controls the flow ratio between the heating passage 14 and the bypass passage 15. Variable. Reference numeral 20 denotes a tapping water detection means provided downstream of the junction 17 and is constituted by a sensor such as a thermistor, and detects a mixing temperature between the heating path 14 and the bypass path 15. 21 is heating path 1
The temperature of the outlet of the heat exchanger 12 is detected by the heating detection means provided in 4. Reference numeral 22 denotes a water temperature detecting means provided upstream of the branch point 16 for detecting a water supply temperature. Reference numeral 23 denotes a water amount detecting means provided in the water inlet 13 to detect the amount of water to the heat exchanger 12. 24
Is a temperature setting means for the user to arbitrarily set the tapping temperature of the tapping water from the tapping path 18, and 25 is a feedforward control means, which inputs and mixes signals from the temperature setting means 24, the heating detection means 21 and the water temperature detection means 22. The flow rate ratio at which the temperature matches the set temperature is calculated. Reference numeral 26 denotes a feedback control unit, which inputs signals from the hot water detection unit 20 and the water temperature detection unit 22 and calculates an operation amount of the ratio adjustment valve so that a deviation between the two signals becomes zero. Reference numeral 27 denotes a ratio controller for controlling the opening degree by driving the ratio adjusting valve 19, and when a signal from the water amount detecting means 23 is inputted and the water amount is detected, the calculated value of the feed forward control means 25 and the feedback control means 26 is calculated. The addition is performed, and the opening degree of the ratio adjustment valve 19 is determined according to the addition result. When the signal of the water amount detecting means 23 is inputted and it is detected that there is no water amount, the feedforward control means 2
The degree of opening of the ratio adjusting valve 19 is determined based on the signal of only 5.
Numeral 28 denotes a combustion controller, the deviation of which becomes zero in accordance with the output deviation between a heating set temperature (for example, set temperature + 20 ° C.) obtained by adding a fixed value to the signal of the heating detection means 21 and the signal of the temperature setting means 24. The amount of gas supplied to the burner 29 is controlled by the opening of the gas proportional valve 30. The feedforward control unit 25, the feedback control unit 26, the ratio controller 27, and the combustion controller 28 are configured by known electronic components such as a microcomputer and a signal input / output interface and software.

Next, the control operation will be described with reference to FIG. The figure shows the control flow of the ratio adjusting valve 19 and the gas proportional valve 30 by the ratio controller 27 and the combustion controller 28. 3
1 determines the presence or absence of hot water supply based on the amount of water detected by the water amount detection means 23. Here, if it is determined that there is an amount of water and hot water is supplied, the combustion control of 32 is performed. Combustion control is performed by the combustion controller 28, and a heating set temperature obtained by adding a fixed value to the set temperature set by the temperature setting means 24 (for example, a set temperature of 40 ° C. and a fixed value of 20 ° C.
° C), and the amount of combustion is controlled by a known PID operation so that the deviation between the temperature detected by the heating detection means 21 and the set heating temperature becomes zero. Next, at 33, the flow rate ratio Rf of the ratio adjusting valve 19 to be controlled by the feedforward control means 25.
Calculate f. 34, the feedback control means 26
The flow rate operation amount Rf to be controlled by the ratio adjustment valve 19
Calculate b. Then, at 35, Rff and Rfb are added, and at 36, the ratio controller 27 controls the valve opening of the ratio adjusting valve 19 based on the added value. The valve opening degree control is performed by adjusting the opening degree of the flow path of the bypass path 15 to thereby control the heating path 14.
The flow rate of the bypass 15 is controlled by changing the flow rate ratio of the bypass path 15 and the feed-forward and feedback control.

The calculation method of the feedforward control means 25 will be described. The mixing temperature Tm is determined in inverse proportion to the flow ratio R of the bypass passage 15 if the heating temperature Th and the feedwater temperature Tw are determined from the following relationship. That is, the bypass path 1
If the opening degree is increased, the mixing temperature Tm decreases. Conversely, if the opening degree is decreased, the mixing temperature Tm increases.

Tm = Tw + (1−R) · (Th−Tw) From this characteristic, a flow rate ratio Rff by feed forward is obtained from the following relationship, where Tm is a set temperature Tset.

Rff = 1− (Tset−Tw) / (Th−Tw) The calculation method of the feedback control means 26 is known so that the deviation between the set temperature Tset and the detection temperature Tm of the hot water detection means 20 becomes zero. The operation amount Rfb of the flow rate ratio is obtained as in the following equation using the PID operation described above.

Rfb = Kp · {e + 1 / Ti · {(e · Δt) + Td · Δe / Δt} where Kp: gain (flow rate ratio / ° C.) e: temperature deviation = Tm−Tset (° C.) Ti: integration time (Second) Σ (e · Δt): integral value of deviation e (° C./second) Δt: temperature detection time interval of tapping detecting means 20 (second) Td: differential time (second) Δe / Δt: differential value of deviation e (° C./sec) On the other hand, if it is determined at 31 that there is no water amount and hot water supply has been stopped, then at 37 the fuel is shut off and combustion is stopped. Then 38
In step 33, the flow rate ratio Rff to be controlled by the feedforward control means 25 for the ratio adjusting valve 19 is calculated.

In the valve opening control at the time of stopping hot water supply in 36, the opening of the ratio adjusting valve 19 is determined based on the flow rate ratio Rff calculated in 38, and drive control is performed. The flow rate ratio and the opening degree of the ratio adjusting valve 19 have a fixed correlation, and the ratio controller 27 uses this correlation obtained in advance to generate a control signal corresponding to the opening degree that becomes the flow rate ratio to be controlled. 19 is output.

As described above, during hot water supply, the proportional adjustment valve 19 is controlled based on the value obtained by adding the control signals of the feedforward control means 25 and the feedback control means 26, so that the feedforward control is stable and responsive. The quick control and the accurate control of the feedback control match, and the mixing temperature can be maintained near the set temperature even when the temperature of the heating path 14 changes suddenly immediately after the hot water is again supplied.

When the hot water supply is stopped, the proportional control valve 19 is controlled based on the control signal of the feedforward control means 25, and the change in the heating temperature due to the post-boiling or cooling, and the change in the water supply temperature due to the seasonal change. Correspondingly, it is possible to always wait at the valve opening at which the mixing temperature becomes the set temperature, so that the difference between the mixing temperature and the set temperature when restarting hot water supply can be reduced.

Further, the combustion amount is controlled so that the heating temperature becomes a heating set temperature obtained by adding a fixed value to the set temperature.
Dew condensation in the heat exchanger 12 can also be prevented.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is different from the above-described embodiment in that
When it is determined that there is a water amount and the hot water is supplied at 0, the flow rate ratio is calculated only by the feedback control means 25 at 42, and the valve opening degree control of the ratio adjusting valve 19 by the ratio controller 27 is performed at 43. Thus, the control configuration is simplified, and even if the heating detecting means 21 or the water temperature detecting means 22
Even if a failure occurs, a required set temperature can be obtained if there is a detection value of the hot water detection means 20.

Next, a third embodiment of the present invention will be described with reference to FIG. 4 is different from the first embodiment in that it is determined at 53 whether or not the elapsed time after the start of hot water supply has exceeded a predetermined value (for example, 10 seconds). In the same manner as in the example, the feedforward flow ratio operation amount Rff calculated in 52 and the feedback flow ratio operation amount Rfb calculated in 54 are added by 55, and based on the added value, the valve opening degree control of the ratio adjustment valve 19 is performed by 56. On the other hand, if it is determined in 53 that the elapsed time has not reached the predetermined value, the valve opening degree control of the ratio adjustment valve 19 is performed in 56 based on only the value of the feedforward flow rate operation amount Rff calculated in 53. To do.

With the above configuration, from the start of hot water supply to the predetermined time, feed ratio calculation conditions of the water temperature detection means 22 and the detection value of the heat detection means 21 and the signal of the temperature setting means are used to control the ratio adjusting valve 19. The opening is determined. Since the water temperature detecting means 22 and the heating detecting means 21 are located upstream of the mixing point 17, the mixing temperature can be predicted in advance. That is, the ratio adjustment valve 19 can be controlled without delay even for a sudden change in the heating temperature immediately after the start of hot water supply. Then, after a predetermined time at which the heating temperature is stabilized, the difference between the mixing temperature and the set temperature generated by the feedforward control can be reduced by adding the feedback control.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The difference from the first embodiment in FIG. 5 is that 60 storage means are provided, and the feedforward control means is parallelized to the first feedforward control means 61 and the second feedforward control means 62. When the ratio controller 63 determines that the hot water supply is stopped, the proportional control valve 19 is controlled to the set opening degree of the second feedforward control means 62, and when it is determined that the hot water is supplied, the first feedforward control is performed. The ratio adjusting valve 19 is determined by the sum of the set opening degrees of the control means 51 and the feedback control means 26.
Is to be controlled. The storage means 60 sequentially stores the water supply temperature detected by the water temperature detection means 22 in a storage medium (not shown) such as a semiconductor memory when the water amount detection means 23 detects the water amount. The first feedforward control unit 61 calculates the flow rate ratio according to the feedwater temperature, the heating temperature, and the set temperature, similarly to the feedforward control unit 25 in the first embodiment. The second feedforward control means 62 calculates the water supply temperature of the first feedforward control means 61 by replacing it with the latest stored value of the storage means 60. That is, the flow rate ratio Rff2 is expressed by the following equation.

Rff2 = 1− (Tset−Mtw) / (Th−Mtw) where Mtw is the latest stored value (° C.) of the storage unit 60. The control operation of the above configuration will be described with reference to FIG.

FIG. 6 differs from the first embodiment in that the supply water temperature is stored during hot water supply at 66 and the supply water temperature, the heating temperature and the set temperature are stored at 67 by the first feedforward control means 51. Calculating the flow ratio accordingly;
At 72, the stored value is read from the storage means 50, and at 73, the flow rate ratio is calculated by the second feedforward control means 52 according to the stored value, the heating temperature, and the set temperature. Therefore, at 70, the flow ratio of the bypass passage 15 is quickly and stably controlled by feedforward and feedback control during hot water supply as in the first embodiment.
On the other hand, while the hot water supply is stopped, the opening of the ratio adjustment valve 19 is determined based on the flow rate ratio calculated by the second feedforward control means 52 and drive control is performed.

The water temperature detecting means 22 can accurately detect the temperature of the supplied water because the heat transfer of the flowing water becomes dominant during the supply of water and the influence of thermal disturbance such as the ambient temperature becomes negligible. However, when the supply of water is stopped, accurate detection becomes difficult due to the influence of thermal disturbances such as convection and conduction from the heat exchanger 12 through the pipeline and heat transfer from the surroundings.

According to the above configuration, the feed-forward operation at the time of stopping hot water supply is performed by replacing the feed water temperature with the stored value of the feed water temperature during the feed water. Does not appear in the calculated value.
Therefore, the accurate ratio adjusting valve 1 can be used both during hot water supply and after hot water supply is stopped.
9 can be controlled.

Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 7 differs from the fourth embodiment in that it is determined at 77 whether or not the elapsed time after the start of hot water supply has exceeded a predetermined value (for example, 10 seconds). As in the example, the water supply temperature is stored at 78 and 79
Then, the first feedforward control means 61 calculates the flow rate operation amount Rff1. Subsequently, at 81, the feedback control means 26 calculates the flow rate operation amount Rfb. Then, at 82, Rff1 and Rfb are added, and based on the added value, the valve opening control of the ratio adjustment valve 19 is performed at 83. On the other hand, when it is determined at 77 that the elapsed time has not reached the predetermined value, 80 The second feedforward control means 62 calculates the flow rate ratio manipulated variable Rff2, and the step 83 performs valve opening control of the ratio regulating valve 19 based on the sum of the Rff2 and the Rfb.

As in the fourth embodiment, the configuration and operation during the stop of hot water supply are based on only the flow rate ratio operation amount Rff2 calculated by the second feedforward control means 62, and the valve opening degree control of the ratio adjustment valve 19 is performed at 83 based on 83. Do.

With the above configuration, the opening of the ratio adjusting valve 19 is determined by the sum of the calculated value of the second feedforward control means 62 and the calculated value of the feedback control means 26 from the start of hot water supply to a predetermined time. That is, the stored value of the feed water temperature was used in the feed forward calculation at the start of hot water supply. This is because the thermal disturbance of the water temperature detection means 22 at the time of stopping hot water supply described in the fourth embodiment still remains immediately after the start of hot water supply, so that the stored value is used for the time until accurate water supply temperature detection can be performed. In this way,
The accuracy of the operation by the feed forward is improved, and the difference between the mixing temperature and the set temperature can be further reduced.

In the above embodiment, a solenoid type proportional control valve is used as the ratio adjusting valve, but the same effect can be obtained by using a motor driven water flow valve.

[0038]

As apparent from the above description, the following effects can be obtained according to the hot water supply control device of the present invention.

(1) The proportional control valve is controlled by the control signal of the feedforward control means based on the feedwater temperature, the heating temperature, and the set temperature, and the change of the heating temperature due to post-boiling or cooling, and the change of the feedwater temperature due to seasonal changes. Since the valve opening can always be controlled so that the mixing temperature becomes the set temperature in response to the change, it is possible to be stable and to reduce the difference between the mixing temperature and the set temperature.

(2) Since the proportional control valve is controlled based on the value obtained by adding the control signals of the feedforward control means and the feedback control means, stable and fast response control of the feedforward control and accurate control of the feedback control are performed. Thus, the mixing temperature can be maintained near the set temperature even when the temperature of the heating path changes suddenly immediately after the hot water is re-discharged.

(3) The ratio control valve is controlled and driven by switching between the set value of the feedback control means and the set value of the feedforward control means in accordance with the amount of water. Since the feedback control means that determines the operation amount of the ratio adjustment valve can be selected, even if the heating detection means or the water temperature detection means fails during hot water supply, the required set temperature can be obtained if there is a detection value of the hot water detection means. Is safe and secure.

(4) There is provided storage means for storing the supply water temperature in a state where the amount of water is detected, and the feedforward control means opens the ratio adjustment valve according to the storage value of the storage means, the heating temperature, and the set temperature. Since the temperature is set, there is no influence of thermal disturbance of the water temperature detecting means occurring when the hot water supply is stopped. Therefore, accurate control of the ratio adjusting valve can be performed both during hot water supply and after hot water supply is stopped.

(5) First feedforward control for providing a storage means for storing the supply water temperature in a state where the amount of water is detected, and setting the opening of the ratio adjustment valve according to the supply water temperature, the heating temperature, and the set temperature. Means, a second feedforward control means for setting the degree of opening of the ratio adjustment valve according to the storage means and the heating temperature and the set temperature, and the second feedforward control means for a predetermined time when the amount of water is detected A ratio controller for controlling and driving the ratio adjusting valve by adding the set value of the feedback control means and thereafter controlling and driving the ratio adjusting valve by adding the set values of the first feedforward control means and the feedback control means. Therefore, the accuracy of the feedforward calculation is improved without being affected by thermal disturbance of the water temperature detecting means remaining immediately after the start of hot water supply. Therefore, the mixing temperature can be controlled to the set temperature immediately after the start of hot water supply.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a hot water supply control device according to a first embodiment of the present invention.

FIG. 2 is a control flowchart of the apparatus.

FIG. 3 is a control flowchart of a hot water supply control device according to a second embodiment of the present invention.

FIG. 4 is a control flowchart of a hot water supply control device according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram of a hot water supply control device according to a fourth embodiment of the present invention.

FIG. 6 is a control flowchart of the apparatus.

FIG. 7 is a control flowchart of a hot water supply control apparatus according to a fifth embodiment of the present invention.

FIG. 8 is a configuration diagram of a conventional hot water supply control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Heat exchanger 14 Heating path 15 Bypass path 19 Ratio adjusting valve 20 Hot water detecting means 21 Heat detecting means 22 Water temperature detecting means 23 Water quantity detecting means 24 Temperature setting means 25 Feed forward controlling means 26 Feedback controlling means 27 Ratio controlling apparatus

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-5-10592 (JP, A) JP-A 1-159547 (JP, A) JP-A 4-151453 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) F24H 1/10 302

Claims (1)

(57) [Claims] A heating path connected to a tapping side of the heat exchanger;
A bypass which bypasses the heat exchanger, a ratio adjusting valve which varies a flow rate ratio between the heating path and the bypass, a water temperature detecting means for detecting a temperature of water supplied to the heating path, and a heat path for the heating path. Heating detection means for detecting a heating temperature downstream of the exchanger; hot water detection means for detecting a mixing temperature downstream of a junction of the heating path and the bypass path; temperature setting means for arbitrarily setting a set temperature; Water amount detection means for detecting the water amount to the exchanger, storage means for storing the water supply temperature in a state where the water amount is detected, and the ratio adjustment valve according to the water supply temperature, the heating temperature and the set temperature First feedforward control means for setting an opening degree, and second feedforward control means for setting an opening degree of the ratio adjusting valve according to a stored value of the storage means, the heating temperature and the set temperature. Feedback control means for setting the opening of the ratio adjustment valve so as to reduce the deviation between the set temperature and the mixing temperature; and the second feedforward control means and feedback control for a predetermined time when the water amount is detected. Ratio control for controlling and driving the ratio adjusting valve by adding the set value of the means, and adding and setting the set values of the first feedforward control means and the feedback control means after the predetermined time. Hot water supply control device equipped with a water heater.