JP4029164B2 - Inspection method for combustion flame detection circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inspection method for a combustion flame detection circuit, and more particularly to an inspection method for evaluating the output of a combustion flame detection circuit constituting a combustion flame detection device.
[0002]
[Prior art]
Conventionally, in general combustion equipment, a combustion flame detector is used to confirm the presence or absence of ignition (the presence or absence of a combustion flame). As such a combustion flame detector, a flame rod is used. What was used is known. That is, this combustion flame detection device inserts one end of a frame rod, which is a metal rod that does not melt even in the combustion flame, into the combustion flame, and applies an AC voltage to the other end. This utilizes the phenomenon that current (frame current) flows in one direction.
[0003]
This combustion flame detection device pays attention to the fact that the combustion flame has a rectifying action, and that a function like a diode is exhibited by a combination of the combustion flame and the flame rod. It will change according to the strength of the. In consideration of such facts, the combination of the combustion flame and the frame rod, which are components of the combustion flame detection device, is expressed as an equivalent of a series circuit formed by combining a diode and a resistor.
[0004]
Specifically, as shown in FIG. 5, the combustion flame detection device specifically includes a frame rod 2 having one end inserted into the combustion flame 1 and a frame rod connection terminal 3 to which the other end of the frame rod 2 is connected. A high-voltage AC signal unit (signal source) 4 and a level shift detection unit 5 which are electrically connected to each other. And the level shift detection part 5 here smoothes the voltage (it becomes a half-wave rectification signal) expressed at the other end of the frame rod 2, and detects the current value of the frame current by detecting the level change, that is, The presence or absence of the combustion flame 1 is detected.
[0005]
In this combustion flame detection device, the L level is output when the flame current is equal to or less than a predetermined current value (current value A), and as a result, it is determined that there is no combustion flame. Further, when the flame current is a predetermined current value different from the current value A (current value B> current value A), the H level is output. In this case, a combustion flame exists. It is judged. In other words, the operation of the combustion flame detection device is regulated by the current value of the flame current. Here, no combustion flame is set to L level, and the presence of combustion flame is set to H level. However, if the output of the detection circuit is inverted, the presence of combustion flame may be set to L level and the absence of combustion flame may be set to H level. Is possible.
[0006]
Further, when inspecting the combustion flame detection device, an inspection method referred to as pinching measurement with upper and lower limits is employed. In this inspection method, the output of the combustion flame detector changes from the L level to the H level at any point in time while the flame current changes from the current value A (lower limit) to the current value B (upper limit). Therefore, it is important to confirm that the L level is output when the frame current is the current value A and the H level is output when the frame current is the current value B.
[0007]
Therefore, a part of the combustion flame detection device, that is, a combustion flame detection circuit in which the combustion flame 1 and the frame rod 2 are omitted, in other words, the high-voltage AC signal unit 4 that is electrically connected to each other via the frame rod connection terminal 3. When inspecting the combustion flame detection circuit composed only of the level shift detection unit 5, as shown in FIG. 6, the dummy load 9, which is a series circuit in which the diode 7 and the resistor 8 are connected in series, is connected to the combustion flame 1. In addition, it is used as a substitute for the frame rod 2. In addition, the code | symbol 10 in FIG. 6 is an ammeter, and this ammeter 10 is connected to the dummy load 9 in series.
[0008]
[Problems to be solved by the invention]
By the way, in the inspection method of the combustion flame detection circuit according to the conventional form, the following inconvenience has occurred. That is, if the level of the AC signal output from the high voltage AC signal unit 4 constituting the combustion flame detection circuit through the frame rod connection terminal 3 is completely fixed, the dummy load 9 is set. The resistance value of the configured resistor 8 may be constant.
[0009]
However, the level of the AC signal output from the high-voltage AC signal unit 4 is generally different for each model of the combustion flame detection circuit, and in order to flow a predetermined current to the dummy load 9, It is necessary to set the resistance value of the resistor 8 corresponding to each model of the combustion flame detection circuit. Then, the level of the AC signal at the time is greatly different from the tens V _pp ~ several hundred V _pp, moreover, not only the flame current is less weak current 1μA is usual.
[0010]
Therefore, the resistor 8 constituting the dummy load 9 needs to have a high resistance of about 100 MΩ to 1000 MΩ. As a result, it is inevitable that the external size of the resistor 8 is, for example, about 60 cm ³ , and a large space is required in the portion constituting the dummy load 9 in the inspection apparatus. End up.
[0011]
Even if the combustion flame detection circuit is of the same model, the level of the AC signal output from the high-voltage AC signal unit 4 varies from product to product. Therefore, in order to avoid inspection mistakes, it is necessary to provide a margin between the upper limit and the lower limit at the time of pinching measurement. However, if the margin is too large, an inspection error that determines a non-defective product as a defective product occurs. There is a fear. Furthermore, even if the AC signal level is the same, if the wiring length to the frame rod 2 (several tens of centimeters to several meters) is different, the signal attenuation is different and the current value of the frame current is also different. .
[0012]
Furthermore, in order to avoid such an inconvenience, the resistor 8 constituting the dummy load 9 is made a variable resistor, and the resistance value of the resistor 8 is manually changed while observing the current value of the frame current. It is considered. However, if the inspection operation is performed while manually changing the resistance value of the resistor 8 which is a variable resistor, another inconvenience of requiring a great amount of labor and time will occur.
[0013]
The present invention was devised in view of these disadvantages, and it is possible to reduce the size of the inspection apparatus without being affected by the level of the AC signal and its variation, and between the upper limit and the lower limit at the time of pinching measurement. It is an object of the present invention to provide a method for inspecting a combustion flame detection circuit that does not require a margin and facilitates inspection work.
[0014]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided an inspection method for a combustion flame detecting circuit that detects the presence or absence of a combustion flame based on a magnitude of a flame current flowing through a flame rod connected to a flame rod connecting terminal that outputs an AC signal. A method for inspecting a combustion flame detection circuit configured as described above, wherein a series circuit composed of a diode and a constant current load for supplying a predetermined current is connected to the frame rod connection terminal as a dummy load in place of the combustion flame and the frame rod In addition, the output of the combustion flame detection circuit is evaluated.
[0015]
In the inspection method according to claim 1, a constant current load is used in place of the conventional resistor, and a dummy load is constituted by the constant current load and the diode, and then the output of the combustion flame detection circuit is evaluated. Is called. That is, as long as the constant current load at this time is a constant current circuit or the like, the current value of the current flowing through the constant current circuit is not affected by the level of the AC signal.
[0016]
Therefore, even if the AC signal level is different for each type of combustion flame detection circuit, there is no need to change the constant current circuit, and the AC signal level is different for each product of the same model. However, it is not necessary to provide a margin between the upper limit and the lower limit at the time of sandwiching measurement. In addition, since the constant current circuit here does not need to have a high resistance, the outer size of the constant current circuit can be smaller than that of a conventional resistor.
[0017]
A method for inspecting a combustion flame detecting circuit according to a second aspect of the present invention is the method according to the first aspect, wherein the constant current load includes a current value changing means, and the constant current is changed by the current value changing means. The output of the combustion flame detection circuit is evaluated while changing the current value of the current flowing through the load.
[0018]
That is, at the time of inspection of the combustion flame detection circuit, it is necessary to change the current value of the current flowing through the constant current circuit which is a constant current load in two ways, an upper limit and a lower limit, but the control voltage setting value can be changed. When a current value changing means using a variable current resistor or a variable current resistance is provided in the constant current load, it becomes easy to change the current value of the current flowing through the constant current load. In this case, since the constant current circuit does not need to have a high resistance, even if the current value changing means is configured by using a variable resistor, the outer size can be small, which hinders the downsizing of the constant current circuit. It will never be done.
[0019]
A method for inspecting a combustion flame detection circuit according to a third aspect of the present invention is the method according to the second aspect, wherein the current value changing means changes the current value in accordance with an applied control voltage. The threshold current at which the output of the combustion flame detection circuit switches is obtained while gradually changing the current value of the current flowing through the constant current load in accordance with the change in the control voltage.
[0020]
According to this inspection method, the current value changing means provided in the constant current circuit changes the current value in accordance with the control voltage, so that feedback control by a computer becomes easy. Therefore, automatic measurement that evaluates the output of the combustion flame detection circuit while gradually changing the current value of the current flowing through the constant current load can be realized easily and at high speed, and the current threshold at which the output of the combustion flame detection circuit is switched. It becomes easy to obtain the value current.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an equivalent circuit diagram showing a method for inspecting a combustion flame detection circuit according to an embodiment, FIG. 2 is an explanatory diagram showing characteristics of a dummy load, and FIG. 3 is a diagram of a combustion flame detection circuit according to a first modification. FIG. 4 is an equivalent circuit diagram showing an inspection method for a combustion flame detection circuit according to a second modification. Since the configuration of the combustion flame detection device itself including this combustion flame detection circuit is not fundamentally different from the conventional form shown in FIG. 5, illustration and description here are omitted.
[0022]
The method for inspecting a combustion flame detection circuit according to the present embodiment is a method employed for pinching measurement of a combustion flame detection device configured using the frame rod 2, and is a part of the combustion flame detection device. Combustion flame detection circuit, that is, a combustion flame detection circuit comprising only the high-pressure AC signal unit 4 and the level shift detection unit 5 which are conducted through the frame rod connection terminal 3 while omitting the combustion flame 1 and the frame rod 2. It is a method of inspection. In other words, the method for inspecting the combustion flame detection circuit according to the present embodiment has the magnitude of the frame current flowing through the frame rod 2 connected to the frame rod connection terminal 3 to which the AC signal from the high-voltage AC signal unit 4 is output. This is an inspection method for a combustion flame detection circuit that constitutes a combustion flame detection device that detects the presence or absence of the combustion flame 1 based thereon.
[0023]
In this inspection method, as shown in FIG. 1, a constant current load for passing a predetermined current and a diode 11, and specifically, a series circuit including a constant current circuit 12 is used as a dummy load 13, and the dummy load 13 Is connected to the frame rod connection terminal 3 as a substitute for the combustion flame 1 and the frame rod 2. In addition, the code | symbol 10 in FIG. 1 is an ammeter, and this ammeter 10 confirms the electric current value of the electric current which flows through the dummy load 13 connected in series. In addition, although the constant current load is assumed to be the constant current circuit 12 here, the constant current load is not limited to the constant current circuit 12 but may be a constant current load.
[0024]
Further, the constant current circuit 12 includes a current value changing unit, and here, the control voltage changing unit 14 capable of changing the set value of the control voltage Vc is used as the current value changing unit. . The control voltage changing unit 14 applies a control voltage Vc to the operational amplifier (differential amplifier) 15 to change the current value of the frame current flowing through the constant current circuit 12 in two ways, an upper limit and a lower limit. It has become.
[0025]
That is, in the method for inspecting the combustion flame detection circuit according to the present embodiment, the set value of the control voltage Vc of the constant current circuit 12 is changed by the control voltage changing unit 14 which is a current value changing means. The output of the combustion flame detection circuit is evaluated as the current value of the current flowing through is changed.
[0026]
In the method for inspecting the combustion flame detection circuit according to the present embodiment, the diode 11 and the constant current circuit 12 constitute a dummy load 13, and the current flowing through the dummy load 13 is set to a desired value to set the combustion flame detection circuit. Is evaluated. In this case, since the dummy load 13 is configured using the constant current circuit 12, the level of the AC signal output from the high voltage AC signal unit 4 through the frame rod connection terminal 3 is several tens. even if you are very different with V _pp ~ several hundred V _pp, the current value of the current flowing through the constant current circuit 12 is not affected by the level of the AC signal.
[0027]
Therefore, even if the level of the AC signal is different for each model of the combustion flame detection circuit, it is not necessary to change the constant current circuit 12, and even if the level of the AC signal is different for each product of the same model. It is not necessary to provide a margin for avoiding an inspection error between the upper limit and the lower limit at the time of sandwiching measurement. In addition, since the constant current circuit 12 that is not affected by the level of the AC signal does not need to have a high resistance of about 100 MΩ to about 1000 MΩ, its outer size can be small, and the dummy load 13 in the inspection apparatus can be reduced. The space of the constituent parts is greatly reduced.
[0028]
By the way, the inventors of the present invention have the characteristics of the conventional dummy load 9 composed of the diode 7 and the resistor 8 and the dummy load 13 composed of the diode 11 and the constant current circuit 12, that is, the level shift detector 5. When the test for comparing the input voltage characteristics to is performed, a test result as shown in FIG. 2 is obtained. According to this test result, substantially the same characteristics are obtained regardless of whether the dummy load 9 (resistive load) using the resistor 8 or the dummy load 13 (constant current load) using the constant current circuit 12 is used. It can be seen that there is no problem even if the constant current circuit 12 is used instead of the resistor 8.
[0029]
In the inspection method for the combustion flame detection circuit according to the present embodiment, the dummy load 13 is constituted by the diode 11 and the constant current circuit 12, and the set value of the control voltage Vc in the constant current circuit 12 is current value changing means. The control voltage is changed by the control voltage changing unit 14. However, only the control voltage changing unit 14 that can change the set value of the control voltage Vc is not used as the current value changing means. As shown in FIG. 3, the control voltage Vc is a fixed voltage, and The resistor 17 connected to the ground side of the NPN transistor 16 driven by the operational amplifier 15 may be a variable resistor, and the resistor 17 as the variable resistor may be used as a current value changing unit.
[0030]
In such a configuration, the current value of the current flowing through the constant current circuit 12 is set by changing the resistance value R of the resistor 17, and current value changing means using a variable resistor is set. When it is, it becomes easy to change the current value of the current flowing through the constant current circuit 12. Even in this case, since the constant current circuit 12 does not need to have a high resistance, the outer size is small even when the current value changing means is configured using the resistor 17 which is a variable resistor. In other words, the downsizing of the constant current circuit 12 is not disturbed.
[0031]
Further, when the dummy load 13 is constituted by the diode 11 and the constant current circuit 12, and the set value of the control voltage Vc in the constant current circuit 12 is changed by the control voltage changing unit 14, FIG. As shown in FIG. 1, the measured value of the ammeter 10 connected in series with the constant current circuit 12, that is, the current value of the current flowing through the constant current circuit 12 is read by a microcomputer (CPU) 18, and the CPU 18 stores in advance. The stored current setting value and the current value of the read frame current may be compared with each other, and the CPU 18 may feedback control the control voltage changing unit 14 based on the difference therebetween.
[0032]
In the case of such an inspection method, the current value of the current flowing through the constant current circuit 12 changes corresponding to the control voltage Vc applied by the control voltage changing unit 14 which is a current value changing means. The threshold current at which the output of the combustion flame detection circuit switches is obtained while gradually changing the current value of the current flowing through the constant current circuit 12. When this method is used, automatic measurement for evaluating the output of the combustion flame detection circuit while changing the current value of the current flowing through the constant current circuit 12 little by little, that is, the output of the level shift detector 5 is automatically performed. Automatic measurement is possible. Therefore, if the switching voltage of the level shift detector 5 is set in advance, it becomes easy to obtain the threshold current at which the output of the combustion flame detection circuit switches.
[0033]
【The invention's effect】
According to a first aspect of the present invention, there is provided a method for inspecting a combustion flame detection circuit, comprising: connecting a series circuit comprising a diode and a constant current load for supplying a predetermined current as a dummy load to a frame rod connection terminal; It is characterized by evaluating. Therefore, it is not necessary to change the constant current load even when the AC signal level is different for each model of the combustion flame detection circuit, and the AC signal level is different for each product of the same model. In addition, there is no need to provide a margin between the upper limit and the lower limit at the time of sandwiching measurement.
[0034]
Furthermore, the outer size of the constant current load that does not need to be high resistance can be reduced, and the constant current load can be downsized without being affected by the level of the AC signal or its variation.
[0035]
According to a second aspect of the present invention, there is provided a method for inspecting a combustion flame detecting circuit, wherein the constant current load includes a current value changing means, and the current value changing means performs combustion while changing the current value of the current flowing through the constant current load. It is characterized by evaluating the output of the flame detection circuit. With such an inspection method, when the combustion flame detection circuit is inspected, it is necessary to change the current value of the current flowing through the constant current load in two ways, an upper limit and a lower limit. The advantage that it becomes easy to change the current value of the flowing current is secured.
[0036]
According to a third aspect of the present invention, there is provided a method for inspecting a combustion flame detecting circuit in which a current value is changed in accordance with a control voltage to which a current value changing means is applied. The threshold current at which the output of the combustion flame detection circuit switches is obtained while gradually changing the current value of the current flowing through the combustion chamber. This inspection method facilitates feedback control by a computer. Therefore, it is possible to easily and quickly realize automatic measurement for evaluating the output of the combustion flame detection circuit while changing the current value little by little, and it becomes easy to obtain the threshold current at which the output of the combustion flame detection circuit is switched. The effect is obtained.
[Brief description of the drawings]
FIG. 1 is an equivalent circuit diagram showing an inspection method for a combustion flame detection circuit according to an embodiment.
FIG. 2 is an explanatory diagram showing characteristics of a dummy load.
FIG. 3 is an equivalent circuit diagram showing an inspection method for a combustion flame detection circuit according to a first modification.
FIG. 4 is an equivalent circuit diagram showing an inspection method for a combustion flame detection circuit according to a second modification.
FIG. 5 is an explanatory diagram showing an overall configuration of a combustion flame detection device according to an embodiment and a conventional embodiment.
FIG. 6 is an equivalent circuit diagram showing an inspection method for a combustion flame detection circuit according to a conventional embodiment.
[Explanation of symbols]
1 Combustion flame 2 Flame rod 3 Flame rod connection terminal 11 Diode 12 Constant current circuit (constant current load)
13 Dummy load 14 Control voltage changing section (current value changing means)
17 Resistor (current value changing means)

Claims (3)

An inspection method for a combustion flame detection circuit that detects the presence or absence of a combustion flame based on the magnitude of a flame current flowing through a flame rod connected to a flame rod connection terminal to which an AC signal is output,
An inspection of the combustion flame detection circuit characterized in that an output of the combustion flame detection circuit is evaluated after connecting a series circuit comprising a diode and a constant current load for supplying a predetermined current as a dummy load to the frame rod connection terminal Method. The constant current load includes a current value changing unit, and the output of the combustion flame detecting circuit is evaluated while changing a current value of a current flowing through the constant current load by the current value changing unit. Item 6. A method for inspecting a combustion flame detection circuit according to Item 1. The current value changing means changes the current value in accordance with the applied control voltage, and the combustion is performed while gradually changing the current value of the current flowing through the constant current load in accordance with the change of the control voltage. 3. The method for inspecting a combustion flame detection circuit according to claim 2, wherein a threshold current of an output of the flame detection circuit is obtained.

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