JP2540994B2 - Combustion detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a combustion detection device such as a hot air heater, and more particularly to a safe operation when an oxygen deficiency occurs.

[Conventional technology]

The conventional combustion detection device, for example, as disclosed in Japanese Patent Laid-Open No. 1-263415, applies a voltage between the burner and the flame rod to measure the magnitude of the current flowing therebetween, and this current, that is, the flame current. However, when the flame spreads due to oxygen deficiency and the abnormal combustion of red fire occurs, the combustion is stopped for safety. Further, as disclosed in Japanese Utility Model Laid-Open No. 59-195362, a short circuit between a burner and a flame rod is detected by an electric circuit, and when the short circuit occurs, combustion is stopped.

[Problems to be Solved by the Invention]

However, the conventional combustion detection device has no means for confirming whether the combustion really stops when the combustion state deteriorates and abnormal combustion occurs.Therefore, burner and flame rod are deteriorated due to aging deterioration or electric circuit failure. If the leakage current increases during the period and the apparent flame current increases, even if abnormal combustion occurs, the flame current will flow to some extent and the combustion will not stop, and the user cannot confirm the state. In some cases, it could cause an oxygen deficiency accident or CO poisoning. Further, in the method of detecting the short circuit between the burner and the flame rod and stopping the combustion, it can be detected only when the leakage current is extremely large, and when the leakage current is about several μA, the combustion is continued and abnormal combustion occurs. However, there is a problem in that it is difficult to prevent an oxygen deficiency accident without extinguishing the fire.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a combustion detection device capable of accurately confirming in a short time whether combustion is surely stopped when abnormal combustion occurs. I am trying.

[Means for solving the problem]

A combustion detection device according to the present invention includes a combustion section, a combustion control section that controls a combustion amount and a combustion air supply amount of the combustion section, and a combustion detection section that detects a combustion state of a flame formed in the combustion section. And a reference value of a preset oxygen deficiency level and a detection value from this combustion detection unit, and an oxygen deficiency determination unit that operates to stop combustion when the detection value is equal to or less than the reference value. An oxygen deficiency operation confirmation means for confirming whether or not the oxygen deficiency determination unit operates by sending a signal to the combustion control unit to forcibly change the combustion amount or the combustion air supply amount to cause abnormal combustion; With a display unit for displaying the state, the combustion control unit forcibly stops the combustion after a predetermined time when the oxygen deficiency determination unit does not operate within a predetermined time from the operation of the oxygen deficiency operation confirmation unit, The display is different from the one when the oxygen deficiency determination unit is operating. It is intended to be displayed on the display means.

[Action]

When the oxygen deficiency operation confirmation means in the present invention is operated, if the combustion detection section or the like has a failure, for example, if the leakage current between the burner and the flame rod is large, the oxygen deficiency determination section operates even after a predetermined time has elapsed. Therefore, the combustion is forcibly stopped after a predetermined time from the operation of the oxygen deficiency operation confirmation means, and the failure state is displayed on the display means.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a combustion detecting device according to an embodiment of the present invention. In the figure, reference numeral 1 is a combustion control unit for controlling the combustion amount, the combustion air supply amount, etc. by signals from a temperature setting unit (not shown) and an indoor temperature detection unit (not shown), and 2 is a combustion control unit 1. A combustion unit that forms a combustion flame according to the determined combustion amount, 3 is a combustion detection unit that detects the combustion state of the combustion flame that is formed in the combustion unit 2, and 4 is a detection value from the combustion detection unit 3 and is preset. When the detected value is less than or equal to the reference value, a signal is sent to the combustion control unit 1 to stop combustion, and the oxygen deficiency determination unit 5 sends a signal to the combustion control unit 1 to determine the combustion amount. Alternatively, when the combustion air supply amount is forcibly changed to cause abnormal combustion for a predetermined time, the oxygen deficiency determination unit 4
Is an oxygen deficiency operation confirming means for confirming whether or not is activated.

FIG. 2 shows the block diagram of FIG. 1 in a concrete circuit diagram. .

The combustion unit 2 described in the block diagram includes a burner 6, an electromagnetic pump 7, a blower 8 for supplying combustion air, and the combustion detection unit 3 includes a frame rod 9, a frame rod 9 and a burner 6. It is composed of a DC power supply 10 for applying a voltage between them, and resistors 11, 12 for converting the magnitude of the current flowing between the frame rod 9 and the burner 6 into a voltage.

13 is a microcomputer (hereinafter referred to as a microcomputer)
This is a memory 13a in which the combustion control unit 1 and the oxygen deficiency determination unit 4 described in the block diagram are stored in advance as a control program, a CPU 13b that performs operations such as calculation and control according to the control program, and combustion detection. An input circuit 13c capable of directly inputting an analog voltage from the section 3 and performing AD conversion
And an output circuit 13d for outputting a control signal to the electromagnetic pump 7, the blower 8, the display 14 and the like. Reference numeral 15 denotes an oxygen deficiency operation confirmation switch which operates as the oxygen deficiency operation confirmation means 5 in the block diagram, and is connected to the input circuit 13c of the microcomputer 13.

The above structure will be described below with reference to the flowchart of FIG.

When combustion is started, first, in step 20, the CPU 13b determines the on / off state of the oxygen deficiency operation confirmation switch 15, and if it is off, normal combustion control is performed in step 21. In this case, the flame current flowing between the frame rod 9 and the burner 6 is converted into a voltage by the resistors 11 and 12, and is constantly input to the input circuit 13c.

This analog voltage is converted into a digital amount by the input circuit 13c and sent to the CPU 13b, and the CPU 13b previously stores the memory 13a.
The reference value io of the oxygen deficiency level written inside is compared (step 22).

It is a well-known fact that the flame current value changes depending on the combustion state, and the flame length increases and the flame current decreases as the indoor oxygen concentration decreases.

When the flame current becomes smaller than the reference value io, the CPU 13b detects the oxygen deficiency, controls the output circuit 13 to stop the electromagnetic pump 7 and the blower 8 to stop the combustion, and the oxygen deficiency indicator lamp in the indicator 14 (Not shown) is turned on to inform the abnormal combustion (step 23) On the other hand, when it is determined in step 20 that the oxygen deficiency operation confirmation switch 15 is ON during the combustion, the process proceeds to step 24 and the CP
U13b controls the pulse signal to the electromagnetic pump 7 to forcibly reduce only the combustion amount. At the same time, the CPU 13b starts counting of the oxygen deficiency operation confirmation timer (step 25).

As is well known, the flame current changes depending on the combustion amount, and the smaller the combustion amount, the smaller the flame current value. If the flame current falls below the reference value io, check the combustion amount in advance and store that value in the memory.
Set it to 13a. In step 24, operation is performed with this combustion amount.

Normally, in step 26, the flame current decreases and the reference value
Since it is less than or equal to io, the routine proceeds to step 23, the combustion is stopped, and the oxygen deficiency indicator lamp in the indicator 14 lights up.

On the other hand, there is a failure in the combustion detection unit 3, etc., the flame rod 9 contacts the burner 6, and the resistance 12
If the amount of current flowing through the flame increases, the flame current value that is larger than the current actually flowing in the flame is detected.
Even if the amount of combustion decreases in step 24, the flame current does not fall below the reference value io.

If the flame current does not fall below the reference value io even after the oxygen deficiency check timer has passed 20 seconds (step 27), display 14
The failure state is displayed with (step 28) and the combustion is stopped (step 29). At this time, sound a warning alarm,
The user may be informed of the danger of use.

The oxygen deficiency operation confirmation timer is a time until the flame current is sufficiently lower than the reference value io when the combustion amount is decreased from normal combustion, for example, 20 seconds is set as in the present embodiment, and 20 seconds are elapsed. Also, when the flame current does not fall below the reference value io, it is regarded as a failure of the combustion detection unit 3 and a failure is displayed and the combustion is stopped.

In this way, even if there is a failure in the combustion detection unit 3 or the like, combustion is forcibly stopped after 20 seconds, so abnormal combustion does not continue for a long time, and the oxygen deficiency operation can be confirmed with confidence. Also, if combustion is forcibly stopped by counting up the operation end of the oxygen deficiency check timer, it is stopped with a failure status display different from the oxygen deficiency display.
It is not necessary for a person to look around for 20 seconds, and the combustion detection unit can be easily inspected without spending time on the production line.

In addition, in the combustion detection device in which the combustion amount is controlled in multiple stages from strong combustion to weak combustion, and the reference value io of the oxygen deficiency level is determined according to each combustion amount, The amount of combustion at which the oxygen deficiency level becomes equal to or less than the reference value io may be determined in advance, and when the oxygen deficiency operation confirmation switch 15 is turned on, the amount of combustion may be reduced to that amount for confirmation.

Incidentally, in the above embodiment, when the oxygen deficiency operation confirmation switch 15 is pressed, the combustion amount is reduced, but the combustion amount is kept as it is, the combustion air supply amount is reduced, and the air supply is insufficient for a predetermined time. Abnormal combustion may be performed to check the oxygen deficiency operation.

Also, the oxygen deficiency operation confirmation means 5 is an oxygen deficiency operation confirmation switch 15
However, if the oxygen deficiency operation check is performed when a plurality of existing switches are simultaneously turned on without providing a new switch, the cost does not increase.

〔The invention's effect〕

As described above, the combustion detection device according to the present invention sends a signal to the combustion control unit to forcibly change the combustion amount or the combustion air amount to cause abnormal combustion for a predetermined time, and the oxygen deficiency determination unit operates. Since it is equipped with an oxygen deficiency operation confirmation means for confirming whether or not abnormal combustion occurs, it is possible to accurately confirm in a short time whether the combustion is actually stopped or not Even if the oxygen deficiency determination unit does not operate due to a failure of the detection unit or the like and the combustion does not stop during abnormal combustion, the combustion is forcibly stopped after a predetermined time from the operation of the oxygen deficiency operation confirmation unit, Since the display means displays a different display from that during the operation of the oxygen deficiency determination unit, the user or service person can check the state at any time, so that an oxygen deficiency accident or a CO poisoning accident can be prevented beforehand. , With peace of mind There is an effect that that. In addition, at the time of manufacturing, an accurate oxygen deficiency operation can be confirmed in a short time on an inspection line, which has an effect of improving productivity.

[Brief description of drawings]

FIG. 1 is a block diagram of a combustion detecting device according to an embodiment of the present invention, FIG. 2 is a circuit diagram of the device, and FIG. 3 is a flow chart for explaining the operation. In the figure, 1 is a combustion control unit, 2 is a combustion unit, 3 is a combustion detection unit, 4 is an oxygen deficiency determination unit, and 5 is an oxygen deficiency operation confirmation means. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A combustion section, a combustion control section for controlling a combustion amount and a supply amount of combustion air in the combustion section, a combustion detection section for detecting a combustion state of a flame formed in the combustion section, An oxygen deficiency determination unit that operates to stop combustion when the detection value from the combustion detection unit and a preset reference value of the oxygen deficiency level are compared, and the detection value is equal to or less than the reference value, and the combustion control Signal to the section to compulsorily change the combustion amount or the combustion air supply amount to cause abnormal combustion for a predetermined time, and an oxygen deficiency operation confirmation means for confirming whether or not the oxygen deficiency determination section operates, and an operating state. Display means for displaying, the combustion control unit forcibly stops the combustion of the combustion unit after a predetermined time when the oxygen deficiency determination unit does not operate within a predetermined time from the operation of the oxygen deficiency operation confirmation unit. , A display different from that when the oxygen deficiency determination unit is operating is displayed. Combustion detection apparatus characterized by displaying on the shown means.