JPH0599502A - Method for controlling gas-flow rate at time when hot water is resupplied from hot water-supplying apparatus - Google Patents

Abstract

PURPOSE:To remarkably shorten the time interval of lowering of hot-water temperature at the time when hot water is resupplied, by a method wherein supposing that the rate of water-flow passing through a boiler body is varied from zero to a definite amount of water, at this point of time when the operation of the title apparatus is shifted to steady operation, a differential component at the time when the hot water is resupplied is carried out, when the resupply of the hot water is started. CONSTITUTION:In order that hot water begins to be resupplied after it is stopped, when water begins to be supplied, an actual water-flow rate Q passing through a boiler body varies from zero to a definite amount of the water Qc. Pre-purge is done at this point of time when the water begins to be supplied and the sequence of ignition is done, following which a main burner is started for combustion and is shifted to steady operation. At this point, supposing that the Q is varied from zero to the Qc, a differential component GdQ at the time when the hot water is resupplied is carried out. That is to say, the Q for a time from the time when the water begins to be supplied to the time t is regarded as the zero in calculation and is carried out, and a gas-flow rate, G=GB+GdQ, i.e., the GdQ is added to a criterion gas-flow rate GB, is supplied to the main burner. In this way, since the fluctuation of flow rate is large and the GdQ is increased, the gas-flow rate supplied to the main burner is also increased and thus strong combustion is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas amount control method for re-leaving hot water in a hot water supply device for supplying an appropriate amount of gas when hot water is again discharged after the hot water supply operation of the hot water supply device is temporarily stopped.

[0002]

2. Description of the Related Art Recently, as a hot water discharge characteristic of a hot water heater, there has been a problem of a hot water discharge characteristic (re-hot water discharge characteristic) at the time of re-hot water discharge in which hot water discharge is temporarily stopped and then hot water is restarted during hot water supply operation of the water heater. That is, at the time of re-hot water discharge, the combustion of the combustor is stopped by stopping the hot water discharge, so the temperature of the hot water remaining in the can of the water heater decreases due to heat dissipation, and heating by restarting combustion is sufficiently performed. In some cases, the cold water from the water inlet passes through the can body and flows out of the hot water outlet, and the hot water temperature may drop significantly.Therefore, control to solve this problem and improve re-hot water characteristics A scheme has been proposed.

Conventionally, as a gas amount control system for a water heater,
A feed-forward (FF) method, a feedback (FB) method, or the like is used. In the FF method, generally, the gas amount G _FF is calculated based on the incoming water temperature Tc, the incoming water amount Qc, etc. to control the gas amount. . On the other hand, in the FB system, there are PI control and PID control, and P during steady combustion is used.
The gas amount G _{FB under} I control is G _FB = G _P + G _I (where
G _P is a proportional component, and G _I is an integral component. The proportional component G _P is a gas amount and an integral component calculated based on the deviation between the detected hot water temperature T _H and the set hot water temperature T s. G _I is the gas amount calculated based on the integration of the deviation between the hot water outlet temperature T _H and the set hot water outlet temperature T s. Further, the gas amount G _FB by PID control during steady combustion is G _FB = G _P + G _I
+ G is what is calculated by _D, derivative component G _D is (usually Q = Qc) can body through water Q is a quantity of gas calculated based on the change amount δQ of.

[0004]

However, in the above-mentioned conventional gas amount control method, at the start of re-leaching hot water, in the FF method, the gas amount G _FF calculated based on the water temperature Tc, the water amount Qc, etc. is used as the reference gas amount. and G _B, also in the FB method is calculated based on the deviation of the integral component G _I as the reference gas amount G _B to the detected hot water temperature T _H and setting the hot water temperature Ts at the time of pouring before stopping for storing The sum of the proportional component G _P (G _P + G _I ) is supplied as the amount of gas at the start of hot spring (see Fig. 4). It is said that the body part is considerably cooled, the heating capacity is insufficient when only the reference gas amount G _B is combusted, and the heating speed is slow, so the temperature of the hot water discharge is significantly reduced, and it takes a long time to recover the hot water temperature. There was a problem (see Figure 5) Further, the detection of the tapping temperature has a time delay, and the time delay of the proportional component G _P calculated on the basis of the deviation between the detected tapping temperature T _H at the start of the re-pour tapping and the set tapping temperature Ts becomes large, The rate of increase in heating capacity is small and the drop in tap water temperature is large,
There was a problem that it took a long time to recover the tap water temperature (see FIG. 5). Even when PID control is adopted in the FB method, the flow rate change of the can body water flow rate Q at the start of re-hot tapping is 0 l / min. To Qc l / min. From the start of water to the start of combustion, the above flow rate change is usually performed during the pre-purge, and therefore there is no flow rate change at the time of transition to the steady operation. Therefore, the differential component G _D
Is zero, and there is a problem that it is difficult to supply a gas amount that can sufficiently raise the hot water outlet temperature without being added to the supply gas amount.

An object of the present invention is to provide a method for controlling the amount of gas when hot water is again tapped in a water heater, which can reduce the drop in hot water temperature when tapping hot water again.

[0006]

Means for Solving the Problems] re tapping when gas amount control method for a water heater of the present invention in order to achieve the above object, in proportion to the deviation between the detected hot water temperature T _H and setting the hot water temperature Ts Proportional component G _P , which is the calculated gas amount, and tapping temperature T
_An integral component G _I which is a gas amount calculated based on the integration of the deviation between _H and the set hot water temperature Ts, and a differential component G _D which is a gas amount calculated based on the change amount δQ of the can body water flow rate Q.
And the amount of gas supplied during steady operation G _FB (G _FB = G
_P + G _I + G _D ) is a gas amount control method for a water heater using a feedback system by PID control, in which water starts to flow at the amount of water input Qc at the start of re-leaving, but pre-purge before shifting to steady operation And the can body water flow rate Q in the ignition sequence is calculated to be zero, and when the main burner is completely ignited and the normal operation is started, the water flow rate is the can body water flow rate Q.
Fluctuates from zero to Qc, and the flow rate change dQ (dQ = Qc) is generated, and the differential component G _dQ is calculated to calculate the integral component G _I when tapping before stop and the detected tapping time when tapping again. It supplies a gas amount G obtained by adding the differential component G _dQ to the sum of the proportional component G _P calculated based on the deviation between the temperature T _H and the set hot water discharge temperature T s. Since it is supplied, the heating rate is increased, and the time width of drop of tapping temperature at the time of tapping again is shortened.
The drop in tap water temperature is reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. As gas amount control method for a water heater, a proportional component G _P is a gas amount that is calculated in proportion to the deviation between the detected hot water temperature T _H and setting the hot water temperature Ts, the hot water temperature T _H and setting the hot water temperature The sum of the integral component G _I , which is the gas amount calculated based on the integration of the deviation from Ts, and the differential component G _D , which is the gas amount calculated based on the change amount δQ of the water flow rate Q in the can body, are steady. Supply gas amount G _FB during operation (G _FB
= G _P + G _I + G _D ).

In the time chart shown in FIG. 1, if the re-outflow is started from the stop of the outflow, when the water flow is started at the start of the re-hot discharge, the actual can body water flow rate Q changes from zero to the water flow rate Qc. After the pre-purge is performed from the start point and then the ignition sequence is performed (time t elapses), the main burner starts combustion and shifts to the steady operation. Assuming that the water amount Q has changed from zero to the water input amount Qc, the differential component G _dQ at the time of tapping again is calculated, that is, from the time when the actual can body water flow amount Q changes from zero to the water input amount Qc (starting time of water flow). The can body water flow rate Q during the time t is calculated as zero, and the reference gas amount G is calculated.
_The gas amount G (G = G _B + G _dQ ) added to _B is supplied to the main burner.

The differential component G _dQ is calculated by the following equation. Set here _{G dQ = A · ΔQ · G} B, A is a constant, Delta] Q is the flow rate differential value, G _B is the integral component G _I during the previous stop tapping, the detected hot water temperature T _H at the time of re-pouring This is the reference gas amount calculated as the sum of the proportional component G _P calculated in proportion to the deviation of the tap water temperature Ts (G _B = G _P + G _I ).

With this configuration, at the start of re-outflow,
Since the differential component G _dQ at the time of tapping again is calculated assuming that the can body water flow rate Q has changed from zero to the water input amount Qc at the time of shifting to the steady operation, the fluctuation range of the flow rate is large and the differential component G _dQ is a large value. As shown in FIG. 2, the amount G of gas supplied to the main burner is increased by the differential component G _dQ , large combustion is performed, and the heating rate is increased. Therefore, as shown in FIG.
It is possible to remarkably shorten the time width for lowering the tapping temperature after tapping again.

When the ignition to the main burner is completed and the operation is shifted to the steady operation, the gas amount control is performed by the feedback system by the above PID control, that is, the supply gas amount G _FB is
G _FB = G _P + G _I + G _D

[0012]

EFFECTS OF THE INVENTION Since the present invention is configured as described above, at the time of restarting hot water, at the time of restarting hot water, it is assumed that the can body water flow rate Q has changed from zero to the water flow rate Qc at the time of shifting to steady operation. since computing the differential component G _dQ, large variation range of flow rate, differential component G _dQ becomes a large value, increases the supply gas amount G to the main burner only differential component G _dQ,
Since large combustion is performed and the heating rate is increased, the time width for lowering the tapping temperature after the tapping can be remarkably shortened.

[Brief description of drawings]

FIG. 1 is a time chart showing a control operation of a control method of the present invention.

FIG. 2 is a time chart showing changes in the amount of supply gas in the control method of the present invention.

FIG. 3 is a time chart showing changes in tapping temperature in the control method of the present invention.

FIG. 4 is a time chart showing changes in the supply gas amount in the conventional control method.

FIG. 5 is a time chart showing changes in tapping temperature in a conventional control method.

Claims (1)

[Claims] 1. The supply gas amount G during steady operation is the sum of the proportional component G _P , the integral component G _I and the derivative component G _D.
FB (G _FB = G _P + G _I + G _D ), which is a gas amount control method for a water heater using a feedback method by PID control, in which the can body water flow amount Q before starting steady operation at the restart of hot water discharge At the time of shifting to steady operation with zero, the water flow rate fluctuates as the can body water flow rate Q fluctuates from zero to the water flow rate Qc.
Calculates the differential component G _dQ as resulted Q, is calculated based on the deviation of the integral component G _I and the detected hot water temperature T _H at the time of re-tapping the set hot water temperature Ts at the time of previous stop tapping A method of controlling the amount of gas when hot water is again discharged from a water heater, characterized in that the amount of gas obtained by adding the differential component G _dQ to the sum of the proportional component G _P is supplied.