JPH05118538A - Safety device for combustion - Google Patents

Abstract

PURPOSE:To carryout a stable and safe combustion even if the wind pressure near the exhaust port and air intake port changes by the outside wind and the pressure in a combustion chamber thereby changes. CONSTITUTION:The output of rotational speed detection section 8 that detects the rotational speed of a blower that makes scavenging supplies combustion air and the output of a blast volume sensor 13 that detects the blast volume near the exhaust port or suction port of the blower is compared by means of a comparator 14 and the deviation is outputted. When the deviation obtained by the comparator is over a value beforehand set for a certain time, an abnormality in the blast volume sensor 13 is detected and, at the same time, if the blast volume sensor 13 is not abnormal, a rotational speed controller 7 is provided which controls the rotational speed of the blower by integrating measured blast volumes, and when measured value reaches a certain value, scavenving is finished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion safety device for diagnosing a failure or deterioration of an air blowing function for pre-purge and post-purge.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a conventional combustion safety device disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. 2-146412, in which 1 is an impeller 1a and a drive motor 1.
Blower composed of b and 2 is a burner, and this burner 2
The amount of fuel is adjusted by the proportional control valve 3. Reference numeral 4 denotes a heat exchanger heated by the burner 2, and this heat exchanger 4 constitutes a gas instant water heater 5 for turning water into hot water.

Reference numeral 6 is a combustion control unit which detects the temperature of hot water discharged from the heat exchanger 4 and adjusts the amount of fuel with the proportional control valve 3 so as to reach a set temperature. The combustion control unit 6 operates the gas instantaneous water heater 5. Manage sequences. Reference numeral 7 is a rotation speed control section (feedback speed control section) for feeding back the rotation speed signal of the rotation speed detection section 8 of the blower 1 in order to supply combustion air corresponding to the fuel amount of the burner 2 set by the combustion control section 6. (Means), the control law is constituted by PID. The rotation speed detection unit 8 is composed of a hall element, a photo coupler, or the like. Reference numeral 9 is a current detection unit that detects the drive current ip of the drive motor 1b that constitutes the blower 1, and reference numeral 10 is a set current unit that sets the drive current of the drive motor 1b at the set rotation speed controlled by the rotation speed control unit 7. The value is set in advance according to the load state of the blower 1 by an experiment or the like. 11 is the current detector 9
Of the current value ip and the set current value is
Reference numeral 12 is an informing unit controlled by the output of the comparison unit 11. The informing unit 12 is activated when the relation of the drive current value ip ≧ the set current value is is satisfied. The notification means 12 is configured to notify the main body of the gas instantaneous water heater 5 or a remote controller with a display lamp or a buzzer sound, and may be any means that can be recognized by the user.

Next, the operation will be described. The rotation speed control unit 7 supplies the blower 1 with the rotation speed detection unit 8 to supply combustion air corresponding to the fuel amount of the burner 2 set by the combustion control unit 6.
The rotation speed signal of is fed back. In addition, the current detection unit 9 controls the drive current ip of the drive motor 1b included in the blower 1.
To detect. From these, the combustion device controls the rotation speed N between the maximum fuel amount and the minimum fuel amount, and the drive current value ip
Is usually a value on the load characteristics. That is, for example, the drive current ip of the drive motor 1b at a certain fuel amount Qga is i
At po, the rotation speed N is No. However, when the intake air of the blower 1 is clogged or foreign matter is attached to the impeller, the load current moves to the abnormal load characteristic and the drive current value ip decreases to ipa, but the rotation speed N is changed by the rotation speed control unit 7. Will be kept. Therefore, the current of the drive motor 1b is detected to monitor the operation state of the blower 1, and an alarm is issued when the drive current ip reaches the abnormal load current value is,
From the blowing characteristics of the pressure P and the driving current ip with respect to the air volume Q shown in FIG. 5, the driving current ipo at the normal load point Ko shown by the solid line moves to the abnormal load point Ka shown by the broken line due to intake clogging of the blower 1, etc. The drive current ip at that time is i
It can be decreased from pa to notify the abnormality of the air blowing configuration.

[0005]

Since the conventional combustion safety device is configured as described above, when detecting the air volume using the rotation speed of the blower 1, the air pressure switch, the air volume sensor, etc. Since the wind pressure near the exhaust port and the intake port changes due to the wind and the pressure inside the combustion chamber changes, the true air volume may not be detected. For this reason, with the configuration that measures the scavenging amount by time, the unburned gas discharge cannot be fully exerted, the amount of air required for combustion cannot be secured, and there is a phenomenon that there is no actual air flow even if the wind pressure rises. There was a problem that it would occur.

The present invention has been made to solve the above problems, and is stable even if the pressure inside the combustion chamber changes due to changes in the wind pressure near the exhaust port and the intake port due to the outdoor wind. In addition, it is an object of the present invention to obtain a combustion safety device capable of safely burning.

[0007]

A combustion safety device according to the present invention is provided with a rotation speed detecting portion for detecting the rotation speed of a blower for supplying scavenging air and combustion air, and an air flow rate provided near the blower. The air volume sensor that detects the, the comparator that outputs the deviation by comparing the rotation speed detected by the rotation speed detection unit and the air quantity detected by the air flow sensor, and the deviation obtained by this comparator is a preset value And a rotation speed control means for accumulating the measured air volume when the air volume sensor is not abnormal.

[0008]

In the combustion safety device according to the present invention, the measurement of the scavenging amount is not performed by the timer, the measured air amount is measured, the scavenging is terminated when the measured value reaches a constant value, and the abnormality of the air amount sensor can be detected. It was done like this.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 is a block diagram of the present invention, and FIG. 2 is a block diagram showing an embodiment of the present invention. In FIGS. 1 and 2, the same or equivalent components as those in FIG. Is omitted. In the figure, 13 is an air flow sensor using a hot wire type flow meter, and the rotation speed detection unit 8 is the blower 1
Since it is possible to accurately measure the number of revolutions, the output shift of the air flow sensor 13 can be measured. Reference numeral 14 is a comparator for taking a deviation between the output of the rotation speed detection unit 8 and the output of the air flow sensor 13,
Reference numeral 5 is a determination means for determining whether the deviation from the comparator 14 exceeds a preset value for a certain period of time, 16
Is a water flow sensor for detecting water flow.

Next, the operation will be described based on the flowchart shown in FIG. When the water flow sensor 16 detects the water flow in step ST1, the drive motor 1b is started in step ST2, and in step ST3, the air flow sensor 13 measures the flow rate, and the rotation speed detection unit 8 detects the rotation speed of the blower 1. Then, the deviation is taken by the comparator 14. Then, it is determined whether or not the deviation exceeds a preset value within a certain time, and the air flow sensor 1
3 is normal, and if the air volume sensor 13 is abnormal, abnormal processing is performed in step ST4. If the air volume sensor 3 is normal, the process proceeds to step ST5 to detect the air volume unit of the scavenging amount such as pre-purge and post-purge, and then the measured air amount is integrated in step ST6, and the scavenging amount becomes a constant amount in step ST7. Judge whether or not When it is detected in step ST7 that the scavenging amount has become constant, scavenging such as pre-purge and post-purge is completed in step ST8, and then ignition is attempted by an ignition device (not shown). When the ignition is not performed smoothly, the air volume of the blower 1 is controlled by the rotation speed control unit 7, and the fuel amount of the proportional control valve 3 is adjusted by the combustion control unit 6 to increase the ignition probability.
When ignition is completed normally, proportional combustion starts. Here, when the air volume becomes unstable due to the influence of the outside wind and the stability of the combustion cannot be obtained, the rotation speed control unit 7 causes the drive motor 1b.
Controls the number of revolutions to adjust the air flow to stabilize combustion.
That is, the amount of air or the amount of fuel is adjusted to perform control so as to obtain an appropriate air-fuel ratio.

On the other hand, even if this combustion stabilization control is measured, when combustion does not occur stably, that is, when the flame is extinguished by deviating from the control range of the air volume and fuel quantity to be adjusted, the combustion is temporarily stopped, and after a certain period of time elapses. Start the combustion sequence again. If normal combustion is not performed even after this, lock out and issue an alarm. As a result, the number of times the alarm is issued and the combustion device is reset can be reduced for the reason other than the reason that the user locks out the combustion due to the original abnormality of the combustion device, and a combustion device with good usability can be obtained. ..

[0012]

As described above, according to the present invention, a rotation speed detecting section for detecting the rotation speed of the blower for supplying the scavenging air and the combustion air, and the air quantity is provided near the blower to detect the air volume. An air volume sensor, a comparator that outputs a deviation by comparing the rotation speed detected by the rotation speed detection unit and the air volume detected by the air quantity sensor, and the deviation obtained by this comparator is set to a preset value for a certain period of time. Since it is configured to have a determination means for detecting an abnormality of the air flow sensor when the air flow rate exceeds, and a rotation speed control means for integrating the measured air volume when the air flow sensor is not abnormal, the measurement of the scavenging air quantity is performed by a timer. There is an effect that the measured air volume is measured without performing the measurement, the scavenging is terminated when the measured value reaches a constant value, and an abnormality of the air volume sensor can be detected.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a configuration of the present invention.

FIG. 2 is a block diagram showing an embodiment of the fuel safety device according to the present invention.

FIG. 3 is a flowchart illustrating the operation of FIG.

FIG. 4 is a block diagram showing an example of a conventional combustion safety device.

FIG. 5 is a blowing characteristic diagram of pressure and drive current with respect to air volume for explaining the operation of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Blower 6 Combustion control unit 7 Rotation speed control unit (rotation speed control means) 8 Rotation speed detection unit 13 Air volume sensor 14 Comparator 15 Discrimination means

Claims (1)

[Claims] 1. A rotation speed detection unit for detecting the rotation speed of a blower for supplying scavenging air and combustion air, an air volume sensor provided near the blower for detecting an air volume, and the rotation speed detection unit. The comparator outputs the deviation by comparing the rotation speed detected by and the air volume detected by the air volume sensor, and the air volume when the deviation obtained by this comparator exceeds the preset value for a certain time. A combustion safety device comprising: a determination unit that detects an abnormality of a sensor; and a rotation speed control unit that integrates a measured air volume when the air volume sensor is not abnormal.