JP2850600B2 - Gas control method for re-watering of water heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the amount of gas at the time of re-watering of a water heater for supplying an appropriate amount of gas at the time of re-watering after temporarily stopping the hot water supply operation of the water heater.

[0002]

2. Description of the Related Art In recent years, as a tapping characteristic of a water heater, a tapping characteristic (a tapping characteristic) at the time of tapping again when tapping is temporarily stopped during the tapping operation of the tap water heater and the tapping is restarted. That is, at the time of hot water supply again, since the combustion of the combustor is stopped by stopping the hot water supply, the temperature of the hot water remaining in the can body of the water heater decreases due to heat radiation, and the heating by restarting the combustion is sufficiently performed. In the meantime, the cold water from the water inlet channel will pass through the can body and flow out of the hot water channel, and the temperature of the hot water may drop significantly, so control to solve this problem and improve the re-watering characteristics A scheme has been proposed.

[0003] Conventionally, as a gas amount control method of a water heater,
A feed-forward (FF) method, a feedback (FB) method, or the like is used. In the FF method, a gas amount G _FF is generally calculated based on an incoming water temperature Tc, an incoming water amount Qc, and the like to control the gas amount. . On the other hand, in the FB system, there are PI control and PID control.
The gas amount G _FB by the I control is G _FB = G _P + G _I (where,
G _P is proportional component, G _I are those calculated by the integral component) proportional component G _P is the amount of gas is calculated based on the deviation of the set tapping temperature Ts and the detected hot water temperature T _H, the integral component G _I is a gas amount calculated based on the integration of the deviation between the set hot water temperature Ts and tapping temperature T _H. Further, the gas amount G _FB by the PID control during steady combustion is given by 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 system, at the start of re-water supply, in the FF system, the gas amount G _FF calculated based on the incoming water temperature Tc, the incoming water amount Qc and the like 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 that the sum of the proportional component G _P a (G _P + G _I) re-tapping start with supplies as a gas volume (see FIG. 4), if a relatively long time which has stopped pouring, during re-tapping start cans the body and is considerably cooled, insufficient heating capacity in the combustion of only the reference gas amount G _B, reduction of tapping temperature to heating rate is slow becomes remarkable, that the long time required for the hot water temperature is restored There was a problem (see Figure 5) The detection of the hot water temperature has had time delay, time delay proportional component G _P calculated based on the deviation of the set hot water temperature Ts and tapping temperature T _H which is detected at the time of re-pouring the start is increased, The rate of increase in heating capacity is small, and the drop in tapping temperature is large,
There was a problem that the time required for the tapping temperature to recover was long (see FIG. 5). Even when the 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-water supply is from 0 l / min. To Qcl / min. between water start to the start of combustion, because usually the flow rate change is performed during the pre-purge, because there is no change in flow rate at the time of transition to the steady operation, the differential component G _D
Is zero, and there is a problem that it is difficult to supply a gas amount that can raise the tapping temperature sufficiently without being added to the supply gas amount.

An object of the present invention is to provide a method for controlling a gas amount at the time of re-watering of a water heater, which can reduce the drop of the temperature at the time of re-watering.

[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 The proportional component _GP which is the calculated gas amount and the tapping temperature T
The integral component G _I is a gas amount which is calculated based on the integration of the deviation between _H and setting the hot water temperature Ts, derivative component G _D is the gas amount calculated based on the change amount δQ can body through water Q
And the supply gas amount G _FB during normal operation (G _FB = G
A _P + G _I + G _D) and the PID control by the gas amount control method of the water heater using a feedback scheme to, but starting the water flow at inlet water Qc during re tapping start, before moving to the steady operation prepurge The water flow rate Q in the ignition sequence is calculated to be zero, and when the ignition of the main burner is completed and the operation shifts to the steady operation, the water flow rate is changed to the body water flow rate Q.
Tapping but fluctuates Qc from zero, and calculates the differential component G _dQ as caused change in the flow rate dQ (dQ = Qc), in which the integral component G _I during the previous stop tapping, was detected at the time of re-pouring and supplies a temperature T _H and setting the hot water temperature Ts gas amount G of sum by adding the differential component G _dQ of the proportional component G _P calculated based on the deviation, a large amount of gas during re-tapping start Since it is supplied, the heating rate increases, and the time width of the drop in tapping temperature at the time of tapping again is reduced,
The drop in tapping temperature is reduced.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One 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 stationary and integral component G _I is a gas amount calculated based on the integration of the deviation between ts, the sum of the differential component G _D is the gas amount calculated based on the change amount δQ can body through water Q Supply gas amount during operation G _FB (G _FB
= And using the feedback system by PID control to _{G P + G I + G D} ).

In the time chart shown in FIG. 1, when the re-water supply is started from the stop of the hot water supply, when the water supply is started at the start of the re-water supply, the actual water supply amount Q of the body changes from zero to the water supply amount Qc. Pre-purge is performed from the start point, and after the ignition sequence is performed (time t has elapsed), the main burner starts combustion and shifts to steady operation. Assuming that the water volume Q has changed from zero to the water input volume Qc, the differential component G _dQ at the time of re- _watering is calculated, that is, from the time when the actual can body water flow volume Q changes from zero to the water input volume Qc (water flow start time). The water flow rate Q during the time t is calculated as zero in the calculation, and the reference gas flow rate G is calculated.
And supplies the addition gas amount G a _{(G = G B + G dQ} ) to the main burner _B.

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 tapping a reference gas amount calculated as the sum of the proportional component G _P calculated in proportion to the deviation of the temperature _{Ts (G B = G P +} G I).

[0010] With this configuration, at the time of starting the hot water re-discharge,
At the time of transition to the steady operation, the differential component G _dQ at the time of re-starting the hot water is calculated assuming that the can body water flow amount Q has changed from zero to the water input amount Qc, so that 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 supply gas amount G to the main burner is increased by the differential component G _dQ , and large combustion is performed to increase the heating rate. As shown in FIG.
It is possible to remarkably reduce the time width of the drop in the tapping temperature after the tapping.

When the ignition of the main burner is completed and the operation shifts to the steady operation, the gas amount control is performed by the feedback method based on the PID control, that is, the supply gas amount G _FB is
The _{G FB = G P + G I} + G D.

[0012]

Since the present invention is constructed as described above, it is assumed that the water flow rate Q of the can body has changed from zero to the water flow rate Qc at the time of the start of re-watering, when the steady-state operation is started. 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 the large combustion is performed and the heating rate is increased, the time width of the drop of the tapping temperature after the tapping can be significantly reduced.

[Brief description of the 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 a change in a supply gas amount in the control method of the present invention.

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

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

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

Claims (1)

(57) [Claims] 1. A a proportional component G _P, integral component G _I and the supply gas amount G during steady-state operation the sum of the differential component G _D
A _{FB (G FB = G P +} G I + G D) and the PID control by the gas amount control method for a water heater with a feedback system for the can body through water Q in before moving to a steady operation during the re-pouring the start At the time when the operation is shifted to the steady operation, the water flow rate changes from zero to the water flow rate Qc when the water flow rate Q changes from zero to d.
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 And supplying a gas amount obtained by adding the differential component _GdQ to a sum of the proportional component _GP and the proportional component _GP .