JPH06229537A - Preventing and controlling method for blow-off of instantaneous hot water supplying apparatus - Google Patents

Abstract

PURPOSE:To improve hot-water supply characteristics of an instantaneous hot water supplying apparatus. CONSTITUTION:An instantaneous hot-water supplying apparatus prevents blow- off by simultaneously operating igniters for a predetermined time when fuel gas amount and air amount are reduced in case of an abrupt decrease in necessary capacity. Thus, the blow-off is prevented, and a rapid reignition in the case of the blow-off is provided to substantially continuously burn, thereby largely improving a variation in a temperature of supplying hot water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow-out prevention control method for an instantaneous water heater.

[0002]

2. Description of the Related Art In a momentary water heater, capacity control is performed to increase or decrease the fuel gas amount and the air amount when the required capacity increases or decreases, but conventionally, the capacity control is generally performed. As a method, a feedback control method,
There is a control method that combines the feedback control method with the feedforward control method, and the control method is the mainstream except for the inexpensive one.

In the feedforward control system,
Water supply temperature Tc [℃] and water supply quantity Q [l / m measured by sensor
in] and the set temperature Ts [° C.], the required capacity is calculated by the following equation and control is performed. Required capacity = (Ts-Tc) x Q x 60 [kcal / h] (however, input = required capacity / efficiency of heat source device) That is, in this control method, the required capacity is changed by changing the set temperature, feed water temperature or feed water amount. The increase / decrease is detected, the fuel gas amount is adjusted by adjusting the opening of the fuel gas valve, and the drive voltage and drive of the combustion fan motor is set to a preset value corresponding to the opening of the fuel gas valve. The air volume is increased or decreased by adjusting the frequency.

On the other hand, in the feedback control method, the required capacity is not directly calculated, but the set temperature is set.
Temperature deviation e (= Ts-Th) between Ts [℃] and tapping temperature Th [℃]
Control is performed according to the manipulated variable (input) calculated corresponding to. In this control method, the increase / decrease in the required capacity is detected by the fluctuation of the hot water temperature, and the fuel gas amount is increased / decreased by adjusting the opening of the fuel gas valve in the same manner as described above. Is adjusted to increase or decrease the air volume.

[0005]

In the above capacity control operation, inconvenience may occur as shown in the time chart of FIG. That is, in general, the combustion fan has poorer responsiveness than the fuel gas valve due to its inertia, so that the change in the air amount is delayed with respect to the change in the fuel gas amount. If the decrease rapidly the fuel gas quantity and the air quantity in response to the rapid reduction (t ₁ time) required capability of instantaneous water heaters are therefore temporarily blow-off becomes excess air (t ₂ time ) Is more likely to occur.

[0006] The blow-off although than is re-ignition operation is performed by the ignition device in the case that happened until actual ignition is started (t ₄ time) to the pre-purge time T (t ₃
Elapse of a predetermined time, such as time) from time to t ₄ time is required, during which the hot water temperature is greatly reduced. The present invention aims to solve such problems.

[0007]

In order to solve the above-mentioned problems, in the present invention, in the instantaneous type water heater, when the fuel gas amount and the air amount are reduced at the same time as the required capacity is rapidly reduced, We propose a blowout prevention control method for an instantaneous water heater that operates an ignition device for a predetermined time.

[0008]

[Function] When the amount of fuel gas and the amount of air are rapidly reduced in response to the rapid decrease in the required capacity, the excess air is temporarily excessive and blowout easily occurs as in the conventional case. Since the ignition device is operating, blowout does not occur, or even if it occurs, prompt reignition is achieved, and substantially continuous combustion is performed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an operation example of the present invention will be described with reference to the time chart of FIG. First, the controller of the instantaneous hot water heater detects a rapid decrease in the required capacity and issues a command to reduce the opening of the fuel gas valve at time t _{1, and} at the same time, the controller of the combustion fan corresponding to the opening of the fuel gas valve It issues a command to adjust the motor drive voltage and the like so that the rotation speed can be obtained, and at the same time issues an operation command for the ignition device.

Although the opening degree of the fuel gas valve becomes small immediately after the time point t ₁ , the rotation speed of the combustion fan does not immediately decrease due to its inertia, but decreases from the time point t ₂ . Therefore t ₁
Since the amount of air does not decrease from time t _{2 to} time t _{2, the} air ratio gradually increases, and excess air tends to blow out easily.

However, since the ignition device is already in operation at this time point, blowout does not occur, or even if it occurs, prompt reignition is achieved, and substantially continuous combustion is performed.

[0012] Thus reaches the t ₃ time, the rotational speed of the combustion fan air ratio stable combustion is performed to obtain become those corresponding to the opening of the fuel gas valve, then ignited at t ₄ time The device ends the operation. The operation duration of the igniter (time from t ₁ to t ₄ ) is set appropriately so that a predetermined time can be obtained even after the time t ₃ by taking into consideration the safety factor in addition to the inertia of the combustion fan. can do.

The above-described method of the present invention can be applied to an appropriate control system including the above-mentioned control system. For example, when applying the feedforward control method, it is possible to detect the increase or decrease in the required capacity by changing the set temperature, the feed water temperature or the feed water volume as described above. Is set in the controller as a set value and compared with the calculated required capacity, so that the above-described control can be performed by detecting a rapid decrease in the required capacity. In addition, when applying the feedback control method, it is possible to detect an increase or decrease in the required capacity by the fluctuation of the tap water temperature, so the controller raises the rise value of the tap water temperature per unit time as the maximum value. By making a comparison, it is possible to detect a rapid decrease in the required capacity and perform the control described above.

[0014]

The present invention is as described above. Therefore, in the case of rapidly reducing the fuel gas amount and the air amount against the rapid decrease in the required capacity, it is possible to prevent or prevent the blowout. Since rapid re-ignition can be achieved and substantially continuous combustion can be performed, fluctuations in the outlet heated water temperature can be significantly reduced.

[Brief description of drawings]

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

FIG. 2 is a time chart showing an operation example of a conventional method.

[Explanation of symbols]

t ₁ , t ₂ , t ₃ , t ₄

Claims (1)

[Claims] 1. An instantaneous water heater, wherein an ignition device is simultaneously operated for a predetermined time when the fuel gas amount and the air amount are reduced in response to a rapid decrease in required capacity. Blowout prevention control method