JPH10103668A - Combustion equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of an extraordinary sound due to vibration of a flame even when a combustion capacity is switched over, by providing a delay time wherein the number of revolutions of a fan is controlled to be smaller than the target number of revolutions for a prescribed time in the case when the combustion capacity is switched over after ignition is detected. SOLUTION: A control of switching over a combustion capacity is executed by opening and closing capacity switchover solenoid valves 5, 6 and 7 selectively. In the case of the minimum capacity, only the solenoid valve 5 is opened to make the quantity of gas minimum, and at the time of the maximum capacity, all of the solenoid valves 5, 6 and 7 are opened to make the quantity of gas maximum. As to an intermediate capacity, at least one of the solenoid valves is opened and thereby the quantity of gas is regulated. Although the target number of revolutions of a fan 4 corresponding to the quantity of gas is set beforehand experimentally, the number of revolutions thereof is controlled to be smaller by a certain rate (e.g. 4%) than the target number of revolutions within a prescribed time after ignition and after switchover of a combustion capacity stipulated by a timer. Thereby the quantity of primary air supplied to a combustion tube is prevented from becoming excessive and a flame is prevented from lifting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus for switching the combustion capacity by increasing or decreasing the number of combustion tubes in a combustion tube.

[0002]

2. Description of the Related Art Conventionally, in a combustion apparatus used for a water heater or the like, the number of combustion pipes constituting a burner is increased or decreased by a capacity switching valve in accordance with a set hot water supply temperature and a flow rate of water to switch combustion capacity. The amount of gas supplied to the burner is controlled by the proportional control valve, and the fan is controlled to a predetermined target speed according to the amount of gas. However, in this type of combustion device, the combustion tube constituting the burner is not sufficiently warmed at the beginning of combustion, so that the amount of primary air supplied to the combustion tube by the fan becomes excessive than an appropriate value for the gas amount, and the combustion tube The concentration of the mixed gas ejected from the flame hole becomes thin. Therefore, the flame formed in the flame hole is unstable, and the lifting from the flame hole is apt to occur, and the flame repeats the lifting and the landing on the flame hole in a short cycle, and the vibration of the flame is caused by the combustion tube or the combustion chamber. There is a problem that an unusual sound like a whistle is generated in resonance with the body of the heat exchanger that forms the heat exchanger.

In order to solve such a problem, for example, one disclosed in Japanese Utility Model Laid-Open No. 2-69249 is
Within a certain time after ignition, the rotation speed of the fan is controlled to be lower than a predetermined target rotation speed corresponding to the gas amount.

[0004]

However, in the above conventional apparatus, a large combustion capacity is not required when the hot water supply temperature at the start of combustion is set low or when the flow rate of water is small. When only the combustion tube ignites, the combustion tube warms up after a certain period of time, and the hot water supply temperature is set to a high temperature immediately after the fan speed reaches the target speed. When switching, the combustion tubes that had not ignited before will immediately burn at the target speed while not sufficiently warm, and the abnormal noise accompanying the flame vibration as described above will occur here. There was a problem of doing.

[0005] The present invention solves the above-mentioned problems, and provides a combustion apparatus capable of preventing generation of abnormal noise due to flame vibration even at the time of combustion capacity switching due to a change in set hot water supply temperature or a change in water flow after ignition. With the goal.

[0006]

In order to achieve the above object, a combustion apparatus according to the present invention comprises a capacity switching valve for switching the combustion capacity by increasing or decreasing the number of combustion tubes in a burner, and a gas supplied to the burner. In a combustion device including a proportional control valve for controlling the amount and a fan controlled to a predetermined target speed corresponding to the gas amount, if the combustion capacity is switched after the detection of ignition, a predetermined time The first feature is that a delay time for controlling the rotation speed of the fan to be lower than the target rotation speed is provided.

According to the combustion apparatus of the first aspect, when the switching of the combustion performance is performed after the detection of the ignition, the rotation speed of the fan is controlled to be lower than the target rotation speed for a predetermined time. Even if some of the combustion tubes are ignited on the small side of the combustion capacity and the combustion capacity is switched to the large side after a certain period of time, wait until the newly ignited combustion tubes have warmed up sufficiently before rotating the fan. Will increase to the target rotation speed. Therefore, a stable flame can be obtained immediately after the switching of the combustion capacity, and generation of abnormal noise due to the vibration of the flame can be prevented.

Further, the combustion apparatus of the present invention is characterized in that the delay time is made variable in accordance with the combustion capacity immediately after switching.

There is no need to set the delay time uniformly depending on the difference in combustion capacity before and after the switching, and the newly ignited combustion tube is sufficiently warmed by the switching, and abnormal noise is generated even when the fan is controlled to the target rotation speed. You have to do it. According to the combustion apparatus of the second aspect of the present invention, when the difference in combustion capacity before and after switching is large, that is, when the number of combustion tubes newly ignited by switching is large, the delay time is long, and conversely, when the difference in capacity is small. That is, when the number of newly ignited combustion tubes is small and the effect of the flame stability of the combustion tubes on the entire burner is relatively small, the delay time is shortened. As a result, while preventing generation of abnormal noise at the time of switching the combustion capacity, by delaying the control to the target rotation speed more than necessary, the combustion continues in a state where the primary air is insufficient, and carbon monoxide and nitrogen An increase in the amount of generated compounds can be prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall configuration diagram of a general water heater using a combustion device of the present invention. FIG. 2 is an explanatory diagram showing a first control example (a), a second control example (b), and a third control example (c) of the combustion device according to the embodiment of the present invention.

As shown in FIG. 1, the water heater comprises a burner 1, a combustion chamber 2, a heat exchanger 3, and a fan 4. The fuel gas is supplied to the burner 1 via the capacity switching solenoid valves 5, 6, and 7, and is mixed with the combustion air supplied from the fan 4 to form a flame in the burner 1 and burn. The ignition of the fuel gas is performed by a spark plug 10. The high-temperature combustion gas generated by the combustion heats the water from the water inlet pipe 12 with the heat exchanger 3, and the hot water is supplied from the hot water pipe 13. The combustion gas after heating the water is exhausted outside the vessel. Reference numeral 9 denotes an embers safety device.

In the water heater having such a configuration, according to a conventionally used control method, when a hot water tap or the like is opened and the water amount detecting device 15 detects the minimum operating water amount or more, the fan 4 is started and the fuel is started. Supply gas to burner 1,
The ignition plug 10 ignites and burns. When the flame detection device 11 detects the ignition of the burner 1, the timer of the control means (not shown) starts, and the proportional control valve 17
, A control signal for controlling the gas amount according to the load is output. That is, a feedforward control component calculated based on a set temperature set by a hot water temperature setter (not shown), an incoming water temperature detected by the incoming water thermistor 14, and a flow rate detected by the water amount detection device 15, and a set temperature And a feedback control component calculated based on the tapping temperature detected by tapping thermistor 16 to calculate a gas amount, and control capacity switching solenoid valves 5, 6, 7 and proportional control valve 17.

The switching of the combustion capacity is controlled by a capacity switching solenoid valve 5,
This is performed by selectively opening and closing 6, 7. When the capacity is minimum, only the solenoid valve 5 is opened to minimize the gas amount, and when the capacity is maximum, the solenoid valves 5, 6, and 7 are all opened to maximize the gas amount. For intermediate capacity, at least one of the solenoid valves is opened to regulate the gas flow. The target rotation speed of the fan 4 corresponding to the gas amount is experimentally determined in advance, but within a predetermined time after the ignition and after the switching of the combustion capacity specified by the timer, a certain ratio from the target rotation speed ( (For example, 4%).

Referring to FIG. 2A, first, when the combustion capacity at the time of ignition is minimum, ignition is performed at the minimum gas pressure P ₁ , and the rotation speed of the fan 4 is P ₁ for T ₁ second after ignition. controlled to 4% lower N ₁₀ than the target rotational speed N ₁ corresponding to. At the beginning of combustion, the temperature of the combustion tube is low, and the amount of primary air entering the combustion tube is slightly larger than usual, so the flame is easy to lift, and abnormal noise is generated by vibration caused by repeated lifting and landing at the flame hole However, the flame is stabilized by lowering the rotation speed of the fan 4 to offset the increase in the amount of primary air, thereby preventing generation of abnormal noise. When T ₁ second elapses after the ignition, the rotation speed of the fan is increased to the target rotation speed N ₁ . Thereafter, when the combustion capability with increasing like the set temperature is switched to the maximum, i.e. when ignited to all the combustion tube at the maximum gas pressure P _2, the newly ignited combustion tube, like the combustion beginning since the temperature is low, increasing the rotational speed at the same time the fan 4 and capability switching the target speed N ₂ corresponding to P _2, abnormal noise is generated due to the vibration of the flame. Therefore capacity after switching T ₂ seconds, by controlling the rotational speed than the N ₂ 4% low N _20, the temperature of the combustion tube to raise the rose to N _2.

[0015] In case of FIG. 2 (b) ignited at the maximum combustion capability, FIGS. 2 (a) and similarly, the ignition after T ₃ seconds target speed N
₂ from 4% lower N ₂₀ controls the rotational speed of the fan 4. Then, when the combustion capability is switched to a minimum, already the temperature of all of the combustion tube is increased, abnormal noise does not occur even simultaneously controlled to the target rotational speed N ₁ and switching. When the combustion capacity before the switching is thus maximum, it is not necessary to control the rotation speed of the fan 4 to be lower than the target rotation speed in the subsequent performance switching. However, as ignition in the combustion capability up as shown in FIG. 2 (c), when the combustion capability at T ₄ seconds less than T ₃ seconds is switched, the T ₃ seconds combined with T ₄ seconds after switching also T ₅ seconds is controlled to lower the rotation speed than the target speed.

The delay time until shifting to the target rotational speed is determined, for example, when the combustion capacity after ignition is switched from minimum to maximum as shown in FIG. 2A or when the combustion capacity is maximum as shown in FIG. 20 seconds, ie T ₂ = T ₃
The temperature of the newly ignited combustion tube is sufficient according to the combustion capacity at the time of ignition and before and after switching, such as = 20 seconds, ignition at the minimum combustion capacity, or 10 seconds when switching from minimum to other than maximum. Allow enough time to ascend. If you set the delay time longer than necessary,
Conversely, shortage of primary air causes an increase in the amount of generated carbon monoxide and the like. Further, the rotation speed of the fan during the delay time may be reduced by about several percent from the target rotation speed, and is not limited to 4%.

[0017]

With the above-described configuration, the combustion apparatus of the present invention can be used for switching the capacity immediately after the start of combustion.
Even if there is a large difference in performance before and after switching, until the flame of the newly ignited combustion tube stabilizes, the combustion speed is controlled by controlling the rotation speed of the fan to be lower than the target rotation speed determined according to the gas amount. There is no excess primary air supplied to the tube and no flame lifting. Therefore, it is possible to prevent the generation of abnormal noise due to the vibration of the flame. In addition, by making the time for controlling the rotation speed of the fan lower than the target variable according to the combustion capacity before and after the switching, the primary air amount is insufficient due to delaying the shift to the target rotation speed more than necessary, and The accompanying increase in the amount of carbon monoxide and nitrogen oxide generated can be prevented.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a general water heater using a combustion device of the present invention.

FIG. 2 is an explanatory diagram showing a control example of a combustion device in an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 burner 2 combustion chamber 3 heat exchanger 4 fan 5 capacity switching solenoid valve 14 water input thermistor 17 proportional control valve

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[Procedure amendment]

[Submission date] December 6, 1996

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

FIG. 2

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsuhiro Morishita 93rd Edocho, Chuo-ku, Kobe, Hyogo Pref. (72) Inventor Keiichi Miura 93rd Edocho, Chuo-ku, Kobe, Hyogo Pref. Inside

Claims (2)

[Claims] 1. A capacity switching valve for switching the combustion capacity by increasing or decreasing the number of combustion tubes in a combustion tube constituting a burner, a proportional control valve for controlling an amount of gas supplied to the burner, and a predetermined value corresponding to the gas amount. When the combustion performance is switched after the ignition is detected in the combustion device including the fan controlled to the set target rotation speed, a delay time for controlling the rotation speed of the fan to be lower than the target rotation speed for a predetermined time is set. A combustion device characterized by being provided. 2. The combustion apparatus according to claim 1, wherein the delay time is variable according to the combustion capacity before and after the switching.