JPS63318421A - Flame current monitoring device - Google Patents

Abstract

PURPOSE:To permit sure discrimination between the abnormality of combustion condition and abnormalities except the combustion condition, by impressing either DC or AC voltage on a flame rod by an external switching signal. CONSTITUTION:When an OFF signal is supplied from a micro-computer 16 to a transistor 9, the potential of an impressing voltage on a flame rod 1 is increased by a bias resistor 4, therefore, the negative half cycle of an AC voltage is eliminated and the AC voltage becomes a DC (pulsation) voltage. On the other hand, when an ON signal is supplied to the transistor 9, the potential of a connecting point between the bias resistor 4 and the transistor 9 drops to an earth potential by the transistor 9, therefore, the impressing voltage on the flame rod 1 becomes an AC voltage. A DC voltage is impressed on the flame rod 1 to decide the existence of abnormal combustion by a comparison between a current IF and S2 as well as S3 while an AC voltage is impressed when the current IF is higher than S4 to compare the current IF with S1 whereby whether the increase of flame current is caused by grounding or not may be decided.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a flame current monitoring device that determines whether there is an abnormality in the combustion state based on the current obtained from a flame rod that detects a combustion flame.

(B) Prior Art This type of flame current monitoring device is used in combustion machines such as hot-air heaters and water heaters, and is used to determine the presence or absence of a flame and the quality of the combustion state. In addition, if the power source for the flame rod is DC, the flame rod may come into contact with the burner during combustion, or soot may adhere between the flame rod and the burner.
Even when Freno Rondo has a ground fault, it is detected as a flame current, which poses a safety problem, so for example,
As disclosed in Japanese Patent No.-42164, AC power sources were generally used.

(c) Problems to be Solved by the Invention However, in the above-described flame current monitoring device that applies alternating current, the flame detection current decreases rapidly when the combustion condition deteriorates, so the degree of abnormality in the combustion condition can be precisely determined. It was difficult to do so.

This invention was made in view of the above facts,
The purpose is to be able to reliably distinguish between abnormalities in the combustion state and the presence or absence of other abnormalities.

(d) Means for Solving Problems The present invention includes a flame rod for detecting a combustion fire, and an 'rf1. source circuit,
The configuration includes means for applying the switching signal to the power supply circuit and for determining whether there is an abnormality in the combustion state or another abnormality based on the current obtained from the flame rod.

(f) Effect With this configuration, for example, it is easy to determine whether there is an abnormality in the combustion state by taking advantage of the advantage of a DC power source that a large flame detection current can be obtained, and at the same time, it is possible to use the advantage of an AC power source to detect a flame. It becomes possible to determine the presence or absence of an abnormality such as a ground fault in the rod, and it becomes possible to reliably determine the presence or absence of various abnormalities by taking advantage of the strengths of each power source.

(f) Example Hereinafter, embodiments of this invention shown in the drawings will be described.

FIG. 1 shows an embodiment of the present invention, which includes a frame rod 1, an AC transformer 2, resistors 3, 4, 5, constant voltage elements 6, 7, 8, a transistor 9, and a DC power terminal 1.
0 and applies either a DC voltage or an AC voltage to the frame rod 1; Current I flowing through the burner 12° resistor 5 and ground 13 circuit
A voltage signal generation circuit 14 that converts F into a voltage signal, an A/D converter 15 that converts the output of this voltage signal generation circuit 14 into a digital signal, and a DC/AC switching signal ( On, current)) is supplied, and the magnitude of the current IF is compared with a predetermined reference value.
It is comprised of a microcomputer 16 that determines the presence or absence of an abnormality based on the comparison results.

In the embodiment device described above, the microcomputer 1
6 supplies an off signal to the transistor 9 of the power supply circuit 11, the potential of the voltage applied to the frame rod 1 is increased by the bias resistor 4, so there is no negative half cycle as shown in FIG. pulsating current). On the other hand, when an on signal is supplied to the transistor 9, the potential at the connection point between the bias resistor 4 and the transistor 9 is lowered to the ground potential by the transistor 9, so the voltage applied to the frame rod 1 becomes as shown in FIG. It becomes an exchange. The dashed line arrow, solid line arrow, and broken line arrow in FIG. 1 respectively indicate the flow of current when direct current is applied, when alternating current is applied during a positive half cycle, and when alternating current is applied during a negative half cycle.

4 and 5 show a first example of operation of the microcomputer 16. FIG. In this operation example, a DC voltage is applied to the flame rod 1, the presence or absence of abnormal combustion is determined by comparing IF with S2 and S3, and an alarm and combustion stop control are performed. In addition, when IF is 84 or more, AC voltage is applied to flame rod 1, and by comparing IF and 81, it is determined whether the increase in flame current is due to a ground fault, and it is determined that it is a ground fault. It emits a signal and stops combustion.

FIG. 6 shows a second example of the operation of the microcomputer 16. In this operation example, an alternating current voltage is applied to the frame rod 1 to determine whether there is a ground fault. Further, when IF is smaller than 86, a DC voltage is applied to the flame rod 1 to check how much the combustion condition has deteriorated, and if necessary, an alarm or combustion stop control is performed. In this diagram,
The relationship between 85 and S8 is S5<36<37<58.

FIG. 7 shows a third example of the operation of the microcomputer 16. In this example of operation, a DC voltage and an AC voltage are alternately applied to the frame rod 1, and the presence or absence of a combustion abnormality and the presence or absence of a ground fault are alternately determined.

In the embodiments described above, since the presence or absence of combustion abnormality is determined when direct current is applied, changes in current IF can be more easily detected than when alternating current is applied, and the combustion state can be precisely determined. Furthermore, as shown in FIGS. 4 and 7, if DC application is given priority over AC application, the influence of current reduction due to wear of the frame rod 1 or adhesion of foreign substances can be reduced, and It is also advantageous in terms of durability.

In addition to determining whether there is a combustion abnormality or a frame rod ground fault, the present invention is also capable of determining whether there is an abnormality in the combustion appliance or abnormal flame current due to cigarette smoke or the like.

(G) Effects of the Invention Since the present invention is configured as described above, it is possible to reliably determine the presence or absence of an abnormality such as a short circuit in the flame rod in addition to an abnormality in the combustion state, and it is extremely useful. .

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram showing a device according to an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the voltage waveform of the frame rod when DC is applied, and Fig. 3 is a diagram showing the voltage waveform of the frame rod when AC is applied. 4 is a flowchart showing the first operation example of the microcomputer, FIG. 5 is a diagram explaining the operation characteristics, FIG. 6 is a flowchart showing the second operation example, and FIG. It is a flowchart showing an example of one operation. 1... Frame rod, 11...t N 00
Road, 16...Mike R "Combiator.

Claims (1)

[Claims] (1) A flame rod that detects a combustion flame, a power supply circuit that applies either DC or AC voltage to the flame rod in response to an external switching signal, and a power supply circuit that applies the switching signal to the power supply circuit and that applies a voltage from the flame rod to the flame rod. A flame current monitoring device characterized by comprising means for determining whether there is an abnormality in the combustion state or other abnormality based on the obtained current.