JPH0719454A - Combustion device - Google Patents

Abstract

PURPOSE:To prepare for an expected change in the condition of combustion and see to both safety of the equipment and optimized combustion by a method wherein the amounts of fuel and air for the output of a combustion sensor when the operation is stabilized are preliminarily stored and, when the operation is in transition, the air/fuel ratio is controlled according to the values in storage. CONSTITUTION:When the device is in a transitional state for the start of combustion, an air/fuel ratio-controlling means 17 controls the number of revolution of a fan 6 on the basis of a signal from a condition-setting means 16 and a value written in a storage means 21 and through a fan-controlling circuit 18. When time has passed sufficiently after the start of the combustion and the temperature of a combustion condition detecting means 8 has risen and become practically stabilized, a signal from an averaging part 15, obtained by processing the output from the combustion condition detecting means 8, is compared with a signal from the condition-setting means 16 and the air/fuel ratio-controlling means 17 thereupon controls the number of revolution of the fan 6. When, through subsequent continuation of the combustion, the thermoelectromotive force of the combustion condition-temperature detecting means 8 has become sufficiently stabilized, the value of the fan-controlling circuit 18 or the value of a fuel-control circuit 20 is stored in the storage means 21 so that at the time of a transition the volume of air is controlled according to the value written in the storage means 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion device which detects a combustion flame and controls the amount of fuel and air flow.

[0002]

2. Description of the Related Art As shown in FIG. 6, a conventional combustion apparatus of this type includes a burner 1, a sensor 2 for detecting a combustion state of the burner 1, and a fan 3 according to a detection value of the sensor 2.
The air-fuel ratio control means 4 controls the air-fuel ratio, and the air-fuel ratio control means 4 obtains the current air-fuel ratio from the relationship between the air-fuel ratio and the output of the sensor 2 obtained in advance and compares it with the target air-fuel ratio. The amount of air blown by the fan 3 is controlled so as to decrease it. Generally, as the sensor 2, a temperature sensor, an oxygen sensor or the like is used.

In this way, detection of excess or deficiency of air or fuel,
The optimum combustion state is controlled by adjustment.

[0004]

However, in the configuration of the conventional combustion apparatus described above, when the temperature of the flame is detected by the sensor 2, for example, there is a response delay until the sensor 2 is sufficiently heated, and within that time. Since the output of the sensor 2 cannot be obtained, if the air-fuel ratio suddenly deviates from the setting due to some reason, detection will not be in time and abnormal heating and blowout will occur.
There was a problem that an abnormal situation such as flashback occurred. Even if the sensor 2 is an oxygen sensor, the response time is similarly slow and there is a problem in safety.

Therefore, the present invention solves the above-mentioned problems by storing the values of the amount of fuel and the amount of air with respect to the output of the combustion sensor at the time of stability, and controlling the air-fuel ratio by the stored values at the time of transition. The first objective is to achieve both safety of equipment and optimal combustion.

A second object of the present invention is to detect a change in the combustion state based on a stored value such as the amount of air, and to ensure safety by issuing an alarm or stopping the operation.

A third object of the present invention is to secure the safety by storing the sensor output, detecting the change of the combustion state, and issuing an alarm or stopping the operation.

[0008]

In order to achieve the first object, a combustion apparatus of the present invention comprises a burner, a fuel control means and a blow control means for supplying fuel and air to the burner, and the burner. Combustion state detection means for detecting the combustion state of, storage means for storing the signal of the air flow rate control means in relation to the signal of the fuel control means during stable combustion, and the signal of the storage means during transient combustion, At the time of stable combustion, air-fuel ratio control means for adjusting the fuel control means or the blow control means by the signal of the combustion state detection means is provided.

In order to achieve the above-mentioned second object, the combustion apparatus of the present invention detects a burner, a fuel control means and a blow control means for supplying fuel and air to the burner, and a combustion state of the burner. Combustion state detection means, air-fuel ratio control means for adjusting the fuel control means or the air flow control means by a signal from the combustion state detection means, and the fuel control means or the air flow rate for the combustion state detection means during stable combustion It is provided with a storage means for storing the signal of the control means in association therewith, and an informing means or an operation stopping means which operates depending on the value of the storage means.

In order to achieve the third object, the combustion apparatus of the present invention is a burner, a fuel control means for supplying fuel to the burner, and an air-fuel ratio for controlling the air-fuel ratio in association with the fuel supply means. Control means, blower control means for adjusting the amount of air to the burner by the air-fuel ratio control means, combustion state detection means for detecting the combustion state of the burner, and signals of the combustion state detection means during stable combustion are stored. Storage means, and an informing means or an operation stopping means that operates depending on the value of the storage means.

[0011]

According to the present invention, the combustion state detecting means at the time of stable combustion, the value of the air amount, etc. are stored by the above construction, and the air blowing control means and the fuel control means are increased / decreased by the signal of the stored value during the transition of combustion. To control the air-fuel ratio. As a result, the flame burns in a stable state. Further, when the stored value approaches the preset value, an alarm is issued, and when the preset value is exceeded and the limit value is reached, the operation of the device is stopped.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 5 is a burner, 6 is a blower control means (hereinafter referred to as a fan) that controls the amount of blown air to the burner 5, 7 is a combustion chamber, and 8 is a combustion state detection means that detects the combustion state of the burner 5, A contact point (not shown) is a thermocouple inscribed in the combustion chamber 7. Reference numeral 9 is a fuel control means for controlling the supply amount of gas as fuel to the burner 5, and 10 is a heat exchanger provided in the upper part of the combustion chamber 7, which is used for a water heater or a bath pot, for example. Reference numeral 11 denotes an air-fuel ratio control device, which includes a detection unit 12 that detects an electromotive force of the combustion detection unit 8 and a correction unit 13 that corrects a detection response delay of the combustion detection unit 8.
The correcting means 13 comprises a state predicting portion 14 for estimating the output of the combustion detecting means 8 from the signal of the detecting portion 12, and an averaging portion 15 for averaging the value. The air-fuel ratio is controlled by the correction means 13
Is compared with the set value of the state setting means 16, and a control signal corresponding to the deviation between the two is output.
And a fan control circuit 18 that drives and controls the rotation speed of the fan 6 according to the signal from the air-fuel ratio control means 17, and a fuel control circuit 20 that drives the fuel control means 9 according to the setting signal from the fuel setting means 19. Composed.

Reference numeral 21 denotes a storage means, which is a signal of the correction means 13 of the combustion state detection means 8 when combustion is stable and the fan control circuit 18
Alternatively, the signal of the fuel control circuit 20 is stored.

As shown in FIG. 2, the air-fuel ratio and the electromotive force of the combustion detecting means 8 have a certain correlation for each combustion amount, and the air-fuel ratio can be obtained by knowing this electromotive force.

In the combustion detecting means 8, the hot junction is heated by the combustion of the burner 5 and an electromotive force is generated due to the temperature difference between the hot junction and the cold junction (not shown). Here, when the combustion state suddenly changes and the temperature around the hot junction suddenly changes, the combustion detection means 8 has an inherent thermal response time delay, and it takes time to generate an accurate electromotive force and stabilize. Similarly, the other combustion state detection means 8 such as the thermistor and the oxygen sensor have their own response time delays. The correction unit 13 predicts a stable state from the output change state of the combustion state detection unit 8 and corrects this response time delay, and the differential value of the time change of the detection value of the detection unit 12 and the heat of the combustion detection unit 8 are corrected. The state prediction unit 14 that multiplies the time constant and the averaging unit 15 that averages the calculated values of the state prediction unit 14 are configured. Combustion detection means 8
Assuming that the thermal response of 1 is a first-order delay, a stable-state electromotive force that cancels the response delay can be obtained by the following differential equation.

Ec = Ei + T × K × (dEi / dt) (Equation 1) where, Ec: electromotive force in stable state Ei: electromotive force in changing state (present) T: thermal time constant of thermocouple dEi / dt: electromotive force However, the change state of electromotive force includes a fluctuation component due to flame fluctuation and noise, and therefore the differential value fluctuates greatly. The averaging unit 15 absorbs this fluctuation component by moving average.

The moving average is used for absorbing fluctuations in measured values in digital measurement, and good results can be obtained if the moving average time is longer than the fluctuation cycle of fluctuation components.

The air-fuel ratio control means 17 compares the output of the correction means 13 with the set value of the state setting means 16 and outputs a proportional control signal to the fan 6 so that the deviation between them becomes small. That is, if the deviation is positive, the fan speed is increased in proportion to the positive level, and if the deviation is negative, the fan speed is decreased in proportion to the negative level.

Next, a normal combustion operation in the above structure will be described. The air supplied from the fan 6 is distributed to the burner 5. The amount of air with respect to the value of the burner fuel is initially driven by the value of the storage means 16 and the fuel mixes with the air inside the burner 5. The air-fuel mixture from the burner 5 is ejected from above to form a flame. The combustion state detecting means 8 is heated by this flame, and thermoelectromotive force is generated as shown in FIG. The time constant T is obtained by sampling the value of this thermoelectromotive force at each time. The thermoelectromotive force Ec in the stable state is estimated by Expression 1 using the value of the time constant thus obtained.

The storage means 21 can store a plurality of values, and an initial value set in advance is written at the beginning.
During the transition of the combustion start, the rotation speed of the fan 6 is controlled by the air-fuel ratio control means 17 via the fan control circuit 18 using the signal of the state setting means 16 and the value written in the storage means 21. A sufficient time has elapsed from the start of combustion and the combustion state detecting means 8
When the temperature rises and becomes almost stable, the signal of the averaging unit 15 calculated from the output of the combustion state detecting means 8 as described above and the signal of the state setting means 16 are compared, and the air-fuel ratio control means 17 causes the rotation speed of the fan 6 to be increased. To control. When the combustion continues in this way and the thermoelectromotive force of the combustion state temperature detecting means 8 is sufficiently stabilized, the values of the averaging unit 15, the fan control circuit 18, or the fuel control circuit 20 are stored in the storage means 21.

When a strong wind blows around the intake / exhaust port and the amount of air suddenly changes in an outdoor installation, or when the amount of combustion suddenly changes greatly, it is determined that it is a transitional time and the amount of air is determined by the value of the memory means 21 written. Control.

The storage means 21 has a plurality of storage elements, and the value thereof is replaced with a new one each time it is used, and when the number of values exceeds the storage capacity, it is sequentially replaced with the old one. Further, when the values of the time constants are far apart due to some abnormality, the values can be removed, the weighted average value can be adopted by emphasizing the new value, or all the stored values can be cleared and changed to the initial values.

FIG. 4 is a control block diagram of another embodiment of the present invention.
Shown in. The value of the storage means 21 is compared with the value of the initial setting means 22, and the notification means 23 and the fuel setting means 19 stop the combustion according to the result. A plurality of values are stored in the initial setting means 22, the combustion state is safe but the combustion performance is not preferable (first level), and the state where partial incomplete combustion occurs and maintenance is required ( The second level) and the state that cannot be used due to abnormal combustion (third level) are set. When the value of the first level continues, the notifying means 23 notifies the user or the like, and when the value of the second level is detected even once, the user is similarly notified. When the value of the third level is detected, the fuel setting means 20 immediately stops the combustion.

FIG. 5 is a control block diagram of another embodiment of the present invention.
Shown in. The signal of the state setting means 16 and the fuel setting means 19 controls the air-fuel ratio control means 17, and the storage means 21 stores the signal of the averaging unit 15 at the time of stable combustion. The signals of the averaging unit 15 at the time of combustion are compared, and if the values exceed the allowable value from the reference value, the signals are sent to the notification unit 23 and the fuel setting unit 19 as described above.

The same effect can be obtained by using a thermistor, an oxygen sensor, or a frame rod as the combustion state detecting means 8.

Further, the control of the blown air amount may be performed not only by controlling the fan rotation speed but also by adjusting the damper opening degree for adjusting the air amount supplied to the burner 5.

[0027]

As described in the above embodiments, according to the combustion apparatus of the present invention, the burner, the fuel control means and the blower control means for respectively supplying the fuel and the air to the burner, and the combustion state of the burner are detected. Combustion state detection means, storage means for storing the signal of the air flow rate control means in relation to the signal of the fuel control means during stable combustion, and the signal of the storage means during transient combustion, and the combustion state during stable combustion Since the air-fuel ratio control means for adjusting the fuel control means or the blow control means by the signal of the detection means is provided, the following effects can be obtained.

The error in the air-fuel ratio is small even during transient combustion such as at the beginning of combustion or during strong winds, good combustion characteristics are obtained, and the emission of carbon monoxide and nitrogen oxides is small. Since the actual value is stored regardless of the variation of the fan during manufacturing or assembly, it is close to the optimum value each time it is used, and the error of the air-fuel ratio is reduced.

Further, since the informing means and the operation stop storing means which are activated by the signal of the storing means are provided, the following effects can be obtained.

An abnormal combustion state can be prevented in advance, and the operation is stopped even if it occurs, which is safe.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a combustion device according to an embodiment of the present invention.

FIG. 2 is an output characteristic diagram of an air-fuel ratio and combustion state detection means showing an example of the combustion device.

FIG. 3 is a response characteristic diagram of a combustion state detecting means of the combustion device.

FIG. 4 is a control configuration diagram of another embodiment of the combustion device.

FIG. 5 is a control configuration diagram of another embodiment of the combustion device.

FIG. 6 is a sectional view of a conventional combustion device.

[Explanation of symbols]

 5 Burner 6 Blower Control Means (Fan) 8 Combustion State Detection Means 10 Fuel Control Means 14 State Setting Means 15 Correction Means 18 Air-Fuel Ratio Control Means 19 Fuel Setting Means 22 Storage Means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location F23N 5/26 101 E (72) Inventor Junichi Ueda 1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. In-house (72) Inventor Hideo Tomita 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor, Yoichi Kimura 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. A burner, a fuel control means and a blow control means for supplying fuel and air to the burner, a combustion state detection means for detecting a combustion state of the burner, and a fuel control means for stable combustion. Storage means for storing the signal of the air flow rate control means in relation to the signal, and the fuel control means or the air blow control means by the signal of the storage means during transient combustion and the signal of the combustion state detection means during stable combustion. A combustion device having an air-fuel ratio control means for adjusting. 2. The combustion apparatus according to claim 1, wherein the storage means stores a plurality of values and outputs an average value thereof. 3. A burner, a fuel control means and a blow control means for supplying fuel and air to the burner, a combustion state detection means for detecting a combustion state of the burner, and a signal from the combustion state detection means Air-fuel ratio control means for adjusting the fuel control means or the air flow control means; storage means for storing signals of the fuel control means or the air flow rate control means for the combustion state detection means during stable combustion in association with each other; A combustion device comprising an informing means or an operation stopping means which operates according to the value of the storage means. 4. A burner, fuel control means for supplying fuel to the burner, air-fuel ratio control means for controlling an air-fuel ratio in association with the fuel supply means, and air quantity to the burner by the air-fuel ratio control means. For controlling the combustion state, a combustion state detecting means for detecting the combustion state of the burner, a storage means for storing a signal of the combustion state detecting means during stable combustion, and an informing means for operating according to the value of the storage means. Or a combustion device equipped with an operation stopping means.