KR101069027B1 - Device and method of wire down detection for gas detection sensor - Google Patents

Abstract

The present invention relates to a device for detecting input / output disconnection of a gas detection sensor and a method thereof, and the device for detecting an input / output disconnection of a gas detecting sensor according to an embodiment of the present invention provides a resistance characteristic that is varied by contact with flammable gas. In the gas detection device having a gas detection sensor having a, an amplification circuit portion for amplifying the output voltage output to the output terminal of the gas detection sensor in accordance with the resistance characteristics, and a conversion circuit portion for converting the amplified output voltage into an output current, An input end disconnection detection unit to block the output voltage from being applied to the conversion circuit unit when at least one of an input terminal or a ground terminal to which power is applied to the gas detection sensor is disconnected; An output end disconnection detecting unit for blocking the output current converted by the conversion circuit unit when the output end of the gas detection sensor is disconnected; A control unit for determining a failure of the gas detection sensor when the output current is not input from the conversion circuit unit; And an alarm unit notifying the defect of the gas detection sensor by the control unit.

Description

I / O disconnection detection device of gas detection sensor and method thereof {DEVICE AND METHOD OF WIRE DOWN DETECTION FOR GAS DETECTION SENSOR}

The present invention relates to an input / output disconnection detection device and a method of the gas detection sensor, and in particular, by detecting whether the gas detection sensor itself is disconnected, it is possible to improve the operation reliability of the gas leakage detection device, An object of the present invention is to provide an input / output disconnection detection device and a method of a gas detection sensor that can prevent a large accident in advance.

Increasing the amount of gas used is accompanied by the enlargement and multiplexing of gas accidents. Most of these gas accidents are characterized by minor gas leaks leading to major accidents.

In order to prevent this, various conventional gas leakage alarm devices have been developed and used, and further, various devices and methods having a self-diagnostic function of the gas leakage alarm device itself have been provided.

However, the above-described conventional gas leakage alarm device having a self-diagnosis function includes a diagnostic function in a detector circuit or a display circuit that ignores the gas detection sensor itself, and only detects whether the input terminal, the output terminal, or the ground terminal of the gas detection sensor is disconnected. There was a problem that it could not be detected.

Therefore, even if one or more of the input terminal, output terminal or ground terminal is disconnected due to the gas detection sensor not being normally installed, the output signal may be judged to be normal operation by receiving the output signal. Not only could not be secured, there was a problem that can cause large accidents.

Accordingly, an object of the present invention, by detecting whether the gas detection sensor itself is disconnected can improve the operation reliability of the gas leakage detection device, and gas detection sensor that can prevent large accidents due to false detection or undetected in advance. An input / output disconnection detecting apparatus and a method thereof are provided.

The object of the present invention is to amplify an output voltage output to an output terminal of the gas detection sensor and a gas detection sensor having a resistance characteristic that is variable by contact with a combustible gas, in accordance with the resistance characteristic. A gas detecting apparatus having an amplifying circuit section and a converting circuit section for converting the amplified output voltage into an output current, wherein when at least one of an input terminal or a ground terminal to which power is applied to the gas detection sensor is disconnected, An input disconnection detection unit to block the output voltage from being applied; An output end disconnection detecting unit for blocking the output current converted by the conversion circuit unit when the output end of the gas detection sensor is disconnected; A control unit for determining a failure of the gas detection sensor when the output current is not input from the conversion circuit unit; It is achieved by the input and output disconnection detection device of the gas detection sensor comprising a; alarm unit for notifying the failure of the gas detection sensor by the control unit.

Here, the input disconnection detecting unit includes a resistor (R19), a first transistor (Q1) and a second transistor (Q2) sequentially connected to the ground terminal of the gas detection sensor, one or more of the input terminal or ground terminal When disconnected and the comparison voltage is not applied to the base of the first transistor Q1 through the resistor R19, both the first transistor Q1 and the second transistor Q2 are open (hereinafter, 'open'). 'Is used as an opposite meaning of' conduction 'to be described later, which means that no current flows between the emitter and the collector.) The output voltage to the collector of the third transistor Q3 included in the conversion circuit part. Authorization may be blocked.

The output disconnection detecting unit may further include an OP AMP (U3D) that outputs a high signal when the gas detection sensor output terminal is disconnected, and an emitter and collector conduct when the high signal is applied to the base. The fourth transistor Q4 may block a flow of the output current from the third transistor Q3 of the conversion circuit unit to the controller.

On the other hand, the object is, according to another embodiment of the present invention, the gas detection sensor having a resistance characteristic that is variable by contact with the combustible gas, and the output voltage output to the output terminal of the gas detection sensor in accordance with the resistance characteristic A method for detecting disconnection of an input / output terminal of the gas detection sensor in a gas detection device having an amplification circuit part for amplifying and a conversion circuit part for converting the amplified output voltage into an output current,

When the comparison voltage is applied to the input disconnection detection unit connected to the ground terminal of the gas detection sensor, the input disconnection detection unit applies the output voltage to the conversion circuit to convert the output current into the output current, and the comparison voltage is applied to the input disconnection detection unit. Blocking the output voltage from being applied to the conversion circuit unit by the input disconnection detection unit if not; When the output voltage is applied to an output disconnection detection unit connected to an output terminal of the gas detection sensor, the output current is output from the conversion circuit unit. If the output voltage is not applied to the output disconnection detection unit, the output current is output from the conversion circuit unit. Blocking output; A control unit for determining a failure of the gas detection sensor when the output current is not input from the conversion circuit unit; It is also achieved by the input and output disconnection detection method of the gas detection sensor comprising a; notifying to the outside from the notification unit by the control unit.

Here, when the output voltage is disconnected from the input terminal disconnection detector, when the comparison voltage is not applied to the base of the first transistor Q1 through the resistor R19 connected to the ground terminal, the first transistor ( Q1) and the second transistor Q2 connected to the first transistor Q1 are sequentially opened, and the collector of the third transistor Q3 of the conversion circuit part connected to the emitter of the second transistor Q2. The method may include blocking the application of the output voltage.

The output terminal disconnection detecting unit may block the output of the output current, outputting a high signal when the output voltage is not applied to the OP AMP (U3D) connected to the output terminal, and the OP AMP ( And blocking the flow of the output current from the third transistor Q3 to the converter while the fourth transistor Q4 connected to U3D receives the high signal and conducts the high signal. .

On the other hand, the object is, according to another embodiment of the present invention, the gas detection sensor having a resistance characteristic that is variable by contact with the combustible gas, and the output voltage output to the output terminal of the gas detection sensor in accordance with the resistance characteristic A gas detecting device having a converting circuit portion for converting to an output current, the gas detecting apparatus provided between the gas detecting sensor and the converting circuit portion, wherein the conversion is performed when the output voltage input from the output terminal of the gas detecting sensor is outside a set normal range. A microcomputer (MCU) for blocking the output current output from the circuit unit; A control unit for determining a failure of the gas detection sensor when the output current is not input from the conversion circuit unit; It is also achieved by the input and output disconnection detection device of the gas detection sensor comprising a; alarm unit for informing the failure of the gas detection sensor by the control unit.

And a fourth transistor provided between the micom and the third transistor Q3 of the conversion circuit unit, wherein the high signal is generated when the micom is out of the set normal range. When the high signal is applied to the base, the fourth transistor Q4 is connected to the emitter and the collector so that the flow of the output current from the third transistor Q3 to the controller is blocked. Can be.

On the other hand, the object is, according to another embodiment of the present invention, the gas detection sensor having a resistance characteristic that is variable by contact with the combustible gas, and the output voltage output to the output terminal of the gas detection sensor in accordance with the resistance characteristic A method for detecting disconnection of an input / output terminal of the gas detection sensor in a gas detection device having a conversion circuit unit for converting the output current into an output current, wherein the output voltage input to the input port of the microcomputer connected to the output terminal of the gas detection sensor is set. Outputting a high signal to the first output port when out of the normal range; A fourth transistor (Q4) is supplied with the high signal from the first output port to the base so that the emitter and the collector are conducted; When the fourth transistor (Q4) is turned on, the output current output from the collector of the third transistor (Q3) flows to the fourth transistor (Q4) to block flow to the controller; A control unit for determining a failure of the gas detection sensor when the output current is not input from the conversion circuit unit; It may also be achieved by the input and output disconnection detection method of the gas detection sensor comprising a; notifying to the outside from the notification unit by the control unit.

Therefore, according to the gas detection sensor input and output disconnection detection device according to the present invention having the above-described structure, by detecting whether the gas detection sensor itself is disconnected, it is possible to improve the operation reliability of the gas leakage detection device, and to detect or misdetect Large accidents caused by detection can be prevented.

1 is a block diagram illustrating an apparatus for detecting a gas input / output disconnection according to an embodiment of the present invention;
FIG. 2 is an equivalent circuit diagram of the gas detection sensor input / output disconnection detection device shown in FIG. 1;
3 is a flow chart of a gas detection sensor input / output disconnection detection method according to another embodiment of the present invention;
4 is a block diagram of a gas detection sensor input / output disconnection detecting device according to another embodiment of the present invention;
FIG. 5 is an equivalent circuit diagram of a gas detection sensor input / output disconnection detection device shown in FIG. 4;
6 is a flowchart of a gas detection sensor input / output disconnection detection method according to the configuration shown in FIG. 4.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

First, referring to FIG. 1, an input / output disconnection detection device 1 of a gas detection sensor according to the present invention includes a gas detection sensor 10, an amplification circuit unit 20, a conversion circuit unit 30, and an input disconnection detection unit 40. ), An output disconnection detection unit 50, a control unit 60, and an alarm unit 70.

The gas detection sensor 10 has a resistance characteristic that is varied by contact with the combustible gas. The gas detection sensor 10 applied to the present invention is an electro-catalytic type and may also be referred to as a catalytic oxidation sensor or a catalytic combustion sensor. These sensors emit heat as the combustible gas / air mixture burns past the hot catalyst surface, increasing the electrical resistance of the platinum coil as a result of combustion, which uses a common bridge circuit to measure the change in resistance. .

In the gas detection sensor 10 of FIG. 2, C is for correction, and D is a detector, and when its contact with gas is combusted, its inherent resistance value is changed and the output terminal (2 of CN2) outputs an output voltage for the change value. do.

The gas detection sensor 10 includes an input terminal CN1 to which power is applied from the outside, an output terminal CN2 to which the detection result is output, and a ground terminal 3 to CN2.

The voltage applied to the input terminal CN2 1 may be provided without limitation according to the type and situation of the sensor, and in the following description of the present invention, it is assumed that 3.3V is applied.

 In this case, the output voltage output to the output terminal 2 of CN2 is maintained in the range of 1.2V to 1.8V. Of course, this may be provided to have a different range value depending on the type of sensor.

The amplifying circuit unit 20 amplifies the output voltage output from the gas detection sensor 10 to the output terminal 2 of CN2 according to the resistance characteristic. This is because the change of the output voltage output to the output stage is small and amplified by the OP AMP (U3A and U3B).

In FIG. 2, TH1 is a temperature compensation circuit for correcting an error according to the temperature of the OP AMPs U3A and U3B, and JP1 is a jumper by a contact for selecting a gas type (LNG or LPG). This ensures accuracy even when the gas components are different.

The conversion circuit unit 30 converts the amplified output voltage into an output current. This is because the distance between the gas detection sensor 10 and the control unit 60 may vary depending on the installation environment. The longer the distance is, the longer the output current is transmitted than the output voltage. In this case, the amplified output voltage is converted into an output current of 4 to 20 mA.

The input terminal disconnection detecting unit 40 blocks the output voltage from being applied to the conversion circuit unit 30 when at least one of an input terminal or a ground terminal to which power is applied to the gas detection sensor 10 is disconnected.

The input disconnection detection unit 40 may be configured in various ways. For example, the input end disconnection detecting unit 40 may be configured as an equivalent circuit as illustrated in FIG. 2. That is, the input disconnection detection unit 40 may include a resistor R19, a first transistor Q1, and a second transistor Q2 sequentially connected to the ground terminal CN3 of the gas detection sensor 10. Can be.

As a result, when at least one of the input terminal CN2 or the ground terminal is disconnected, and the comparison voltage is not applied to the base of the first transistor Q1 through the resistor R19, the first transistor Q1 and the second transistor are prevented. All of the transistors Q2 are opened to block the application of the output voltage to the collector of the third transistor Q3 included in the conversion circuit unit 30.

If this is described in detail through the equivalent circuit of Figure 2, when both the input terminal (C1 of CN2) and the ground terminal (3 of CN2) are normally connected, for example, the gas detection sensor 10 is normally mounted, the input terminal (CN2) 1) and the ground terminal (3 of CN2) are not all disconnected, the diode (D4) through the ground terminal (3 of CN2) when power is supplied to the gas detection sensor 10 through the input terminal (1 of CN2) Ground through). At this time, a reference voltage of about 0.8 V is applied to the base of the first transistor Q1 by the resistor R19, and the emitter and the collector of the first transistor Q1 are turned on by the comparison voltage. As the collector of the first transistor Q1 is grounded, the emitter and the collector of the second transistor Q2 also become conductive. Therefore, the power supply VDD is supplied to the collector of the second transistor Q2, and a voltage is applied to the NORM portion. As a result, since the voltage is applied to the collector of the third transistor Q3, the conversion circuit unit 30 generates an output current.

However, when the gas detection sensor 10 is not mounted correctly, or when one or more of the input terminal CN2 1 and the ground terminal 3 of CN2 are disconnected, the comparison voltage is applied to the base of the first transistor Q1. Since it is not applied, the first transistor Q1 is opened. Accordingly, since the second transistor Q2 is also opened, the power supply VDD is not supplied to the collector of the second transistor Q2, and as a result, the output of the output voltage is cut off at the output terminal CN2.

The output terminal disconnection detecting unit 50 blocks the output current converted by the conversion circuit unit 30 when the output terminal of the gas detection sensor 10 is disconnected.

The output disconnection detection unit 50 may be configured in various ways as well, for example, may be configured as an equivalent circuit as shown in FIG. In other words, the output disconnection detecting unit 50 is the OP AMP (U3D) for outputting a high (hIGH) signal when the output terminal (2 of CN2) of the gas detection sensor 10 is disconnected, and when the high signal is applied to the base The emitter and the collector may be electrically connected to each other, and may include a fourth transistor Q4 which blocks the flow of the output current from the third transistor Q3 of the conversion circuit unit 30 to the controller 60.

The output current interruption process of the output disconnection detecting unit 50 will be described with reference to FIG. 2 as an example.

First, when the input terminal CN2 1 of the gas detection sensor 10 is disconnected and power is not supplied, or the output terminal 2 is disconnected, the output voltage is not output. Therefore, the OP of the output disconnection detection unit 50 is not provided. The potential at pin 12 of AMP (U3D) is 0V. At this time, since the potential of pin 13 of the OP AMP (U3D) is also grounded, it has a potential of 0V, so a high signal is output to the 14 pin of the OP AMP (U3D). Accordingly, when a high signal is input to the base of the fourth transistor Q4, the emitter and the collector of the fourth transistor Q4 become conductive, and the output current output from the third transistor Q3 of the conversion circuit unit 30 connected thereto. Flows to the fourth transistor Q4, the output of which is cut off while the potential of pin 2 of CN1 toward the controller 60 becomes 0V.

On the other hand, when both the input terminal CN2 and the output terminal CN2 are not disconnected, the output voltage is applied to pin 12 of the OP AMP U3D to generate a potential difference with pin 13, so that the OP AMP ( A low signal is output to pin 14 of U3D), and accordingly, the emitter and the collector of the fourth transistor Q4 are opened, and the output output from the third transistor Q3 of the conversion circuit unit 30 is performed. The current is input toward the controller 60.

 If the output current is not input from the conversion circuit unit 30, the controller 60 determines a failure of the gas detection sensor.

As described above, when at least one of the input terminal CN2 1 or the ground terminal 3 of the CN2 of the gas detection sensor 10 is disconnected, the output voltage is not applied by the input terminal disconnection detecting unit 40. When the output current is not input to the controller 60, and the output terminal (2 of CN2) of the gas detection sensor 10 is disconnected, the output current is input to the controller 60 by the output terminal disconnection detecting unit 50. Is blocked.

Therefore, the controller 60 determines whether the gas detection sensor 10 is disconnected based on whether the output current is received from the conversion circuit unit 30, and if it is determined that the output current is defective, through the alarm unit 70. This can be announced to the outside.

The alarm unit 70 may be provided without limitation to various known types such as a visual or audio method.

Hereinafter, with reference to the accompanying FIG. 3, a method for detecting an input / output disconnection of a gas detection sensor according to the present invention will be described.

First, depending on whether the comparison voltage is applied to the input terminal disconnection detecting unit 40 connected to the ground terminal CN3 of the gas detection sensor 10 (S11), when the comparison voltage is applied, the input terminal disconnection detecting unit 40 is applied. When the output voltage is applied to the conversion circuit unit 30 so as to be converted into an output current (S4), and the comparison voltage is not applied to the input disconnection detection unit 40, the input circuit disconnection detection unit 40 converts the conversion circuit unit 30. Blocking the output voltage is applied to (S13).

When the output voltage is applied according to whether the output voltage is applied to the output disconnection detection unit 50 connected to the output terminal (2 of CN2) of the gas detection sensor 10 simultaneously or sequentially with the step (S21), the conversion is performed. The output current is output from the circuit unit 30 (S4), and if the output voltage is not applied, the conversion circuit unit 30 blocks the output current from being output (S23).

Next, the controller 60 determines whether the output current is input from the conversion circuit unit 30 (S51). If the output current is not input, the controller 60 determines that the gas detection sensor is defective and alerts the outside (S52).

On the other hand, when the output current is input to the controller 60, the input current is compared with the set output current value to determine whether the gas leak (S61), if it is determined that the gas leakage to inform the outside ( S63), if it is determined that the gas is not leaking, the output current value is input again from the gas detection sensor 10 to determine whether the gas leaks.

Therefore, according to the input / output disconnection detecting device and method of the gas detection sensor according to the present invention having the above-described structure, it is possible to determine whether the sensor is defective by detecting the disconnection of the gas detection sensor itself.

Next, a gas detection sensor input / output disconnection detection apparatus and method according to still another embodiment of the present invention will be described with reference to FIGS. 4 to 6.

Referring to FIG. 4, the gas detection sensor input / output disconnection detecting device 1 according to the present embodiment includes a gas detection sensor 10, a microcomputer 80, a conversion circuit unit 30, a control unit 60, and an alarm. The unit 70 is included. Prior to the description, the same configuration as in the above embodiment will be omitted, and the differences in the present embodiment will be mainly described.

The microcomputer 80 is provided between the gas detection sensor 10 and the conversion circuit unit 30 and, when the output voltage input from the output terminal (2 of CN2) of the gas detection sensor 10 is outside the set normal range, the conversion The output current output from the circuit unit 30 is cut off.

More specifically, referring to FIG. 5, when the input terminal CN2 1, the output terminal CN2 2, and the ground terminal CN3 3 of the gas detection sensor 10 are all normal, the output terminal CN2 2. The output voltage output through is about 2.0 ~ 2.6V when the applied power is 3.3V.

The normal range means the range of the output voltage when the gas detection sensor 10 is normally operated. In this example, the normal range may be set to 2.0 to 2.6V. Here, the normal range may be set differently according to the applied voltage, and may be set differently according to the type of the gas detection sensor or the configuration of the circuit diagram.

On the other hand, when the input terminal CN2 1 or the ground terminal 3 of CN2 of the gas detection sensor 10 is disconnected, the output voltage output through the output terminal 2 of CN2 is either the minimum voltage (0V) or the maximum voltage ( Applied voltage, for example, 3.3V in FIG.

Alternatively, when the disconnection (or poor connection) of the output terminal CN2 or the gas detection sensor 10 is old, the output voltage output through the output terminal CN2 2 may be out of the normal range.

Accordingly, when the output voltage inputted through the input port is out of the set normal range (including the lowest voltage or the maximum voltage), the microcomputer 80 receives the high voltage at the first output port (pin 39 in FIG. 5). When the (High, maximum voltage, for example, 3.3V) signal is applied, the emitter and collector of the fourth transistor Q4 become conductive. Meanwhile, since the emitter of the fourth transistor Q4 is connected to the emitter of the third transistor Q3 of the conversion circuit unit 30, the output current output from the conversion circuit unit 30 flows in the direction of the fourth transistor Q4. To block the output current from being output to the controller 60.

Meanwhile, when the output voltage is input from the microcomputer 80, an auxiliary circuit for expanding the output voltage of the output terminal when the output voltage is narrow may be further provided. For example, the output voltage of the output terminal (2 of CN2) is converted to 10-bit hexadecimal number by the ADC (Analog to Digital Convertor) function of pin 19 of the microcomputer 80. In some cases, the output voltage is narrower than the resolution of the microcomputer 80, so that it may be difficult to read an accurate value.

To this end, as shown in FIG. 5, resistors R6 and R7 are set such that pin 21 of the microcomputer 80 takes a voltage of 1.8V, and pin 2.8V of pin 22 of the microcomputer 80 is used. By setting the values of the resistors R8 and R9 such that the output voltage is extended, the voltage range of the output voltage is expanded, so that even when the resolution of the microcomputer 80 is relatively low, the accurate change of the output voltage can be read. (In this case, the normal range is 1.8 to 2.8 V. Corresponding to step S110 of calculating an input voltage in FIG. 6)

On the other hand, after calculating the input voltage, the microcomputer 80 outputs the modulated output voltage to the output port (pin 40 in FIG. 5) by performing pulse width modulation (PWM).

The conversion circuit unit 30 converts the output voltage input from the OP AMP U4B into an output current and outputs it to the controller 60 through the third transistor Q3 and the diode D2.

The overall flow of the input / output disconnection detection method of the gas detection sensor according to the above-described embodiment will be described with reference to FIG. 6.

First, the microcomputer 80 receives an output voltage through an input port connected to an output terminal 2 of CN2 of the gas detection sensor 10. The microcomputer 80 determines whether the input output voltage is within a set normal range (S100).

When the output voltage is out of the normal range, it is determined that the gas detection sensor 10 is abnormal and the output current output from the conversion circuit unit 30 to the control unit 60 is cut off (S120). The controller 60 determines whether the output current is input (S140), and if the output current is not input, determines that it is an abnormality of the sense detection sensor and notifies the outside through the alarm unit 70 (S150).

On the other hand, if the output voltage is within the normal range, the control unit 60 performs the pulse width modulation and outputs it to the conversion circuit unit 30 through the output port (S110). The conversion circuit unit 30 converts the output voltage into an output current and outputs it to the control unit 60 (S130).

The controller 60 compares the received output current with a set safety range value and alerts the gas leakage fact (S170).

1: I / O disconnection detection device of gas detection sensor
10 gas detection sensor 20 amplification circuit unit
30: conversion circuit section 40: input disconnection detection section
50: output disconnection detection unit 60: control unit
70: alarm unit 80: micom

Claims (9)

A gas detection sensor having a resistance characteristic variable by contact with flammable gas, an amplifying circuit section for amplifying an output voltage output to an output terminal of the gas detection sensor according to the resistance characteristic, and the amplified output voltage as an output current. In the gas detection device having a conversion circuit portion for converting,
An input end disconnection detection unit to block the output voltage from being applied to the conversion circuit unit when at least one of an input terminal or a ground terminal to which power is applied to the gas detection sensor is disconnected;
An output end disconnection detecting unit for blocking the output current converted by the conversion circuit unit when the output end of the gas detection sensor is disconnected;
A control unit for determining a failure of the gas detection sensor when the output current is not input from the conversion circuit unit;
And an alarm unit for informing the defect of the gas detection sensor by the control unit. The method of claim 1,
The input disconnection detector includes a resistor (R19), a first transistor (Q1) and a second transistor (Q2) sequentially connected to the ground terminal of the gas detection sensor, one or more of the input terminal or the ground terminal is disconnected When the comparison voltage is not applied to the base of the first transistor Q1 through the resistor R19, both the first transistor Q1 and the second transistor Q2 are opened to be included in the conversion circuit part. 3. The input / output disconnection detecting device of the gas detection sensor, characterized in that the application of the output voltage to the collector of the three transistors (Q3) is cut off. The method of claim 1,
The output terminal disconnection detecting unit may include an OP AMP (U3D) that outputs a high signal when the gas detection sensor output terminal is disconnected, and an emitter and collector become conductive when the high signal is applied to the base. And a fourth transistor (Q4) for interrupting the flow of the output current from the third transistor (Q3) of the conversion circuit unit to the control unit. A gas detection sensor having a resistance characteristic variable by contact with flammable gas, an amplifying circuit section for amplifying an output voltage output to an output terminal of the gas detection sensor according to the resistance characteristic, and the amplified output voltage as an output current. In the method for detecting the disconnection of the input and output terminal of the gas detection sensor in the gas detection device having a conversion circuit unit for converting,
When the comparison voltage is applied to the input disconnection detection unit connected to the ground terminal of the gas detection sensor, the input disconnection detection unit applies the output voltage to the conversion circuit to convert the output current into the output current, and the comparison voltage is applied to the input disconnection detection unit. Blocking the output voltage from being applied to the conversion circuit unit by the input disconnection detection unit if not;
When the output voltage is applied to an output disconnection detection unit connected to an output terminal of the gas detection sensor, the output current is output from the conversion circuit unit. When the output voltage is not applied to the output disconnection detection unit, the output current is output from Blocking output;
A control unit for determining a failure of the gas detection sensor when the output current is not input from the conversion circuit unit;
And a step of notifying the outside of the notification unit by the control unit. The method of claim 4, wherein
The blocking of the output voltage by the input disconnection detector may include: when the comparison voltage is not applied to the base of the first transistor Q1 through the resistor R19 connected to the ground terminal, the first transistor Q1. And sequentially opening the second transistor Q2 connected to the first transistor Q1, and the collector of the third transistor Q3 of the conversion circuit part connected to the emitter of the second transistor Q2. I / O disconnection detection method of the gas detection sensor comprising the step of interrupting the application of the output voltage. The method of claim 4, wherein
The output terminal disconnection detecting unit may block the output of the output current, outputting a high signal when the output voltage is not applied to the OP AMP (U3D) connected to the output terminal, and the OP AMP (U3D). A fourth transistor (Q4) connected to the input block receiving the high signal to a base to block the flow of the output current from the third transistor (Q3) to the control unit while the emitter and the collector are connected; I / O disconnection detection method comprising a. In the gas detection device having a gas detection sensor having a resistance characteristic that is variable by contact with a combustible gas, and a conversion circuit portion for converting the output voltage output to the output current of the gas detection sensor in accordance with the resistance characteristic to an output current,
A microcomputer (MCU) provided between the gas detection sensor and the conversion circuit unit to block the output current output from the conversion circuit unit when the output voltage input from the output terminal of the gas detection sensor is outside the set normal range;
A control unit for determining a failure of the gas detection sensor when the output current is not input from the conversion circuit unit;
And an alarm unit for informing the defect of the gas detection sensor by the control unit. The method of claim 7, wherein
Further comprising a fourth transistor (Q4) provided between the micom and the third transistor (Q3) of the conversion circuit portion, if the micom is out of the set normal range of the output voltage input from the gas detection sensor output terminal is high ( Outputs a high signal, and when the high signal is applied to the base, the fourth transistor Q4 conducts an emitter and a collector to conduct the flow of the output current from the third transistor Q3 to the controller. Input and output disconnection detection device of the gas detection sensor, characterized in that the cut off. In the gas detection device having a gas detection sensor having a resistance characteristic that is variable by contact with the combustible gas, and a conversion circuit portion for converting the output voltage output to the output current of the gas detection sensor in accordance with the resistance characteristic to an output current In the method for detecting the disconnection of the input and output terminal of the detection sensor,
Outputting a high signal to a first output port when the output voltage input to the input port of the microcomputer connected to the output terminal of the gas detection sensor is outside a set normal range;
A fourth transistor (Q4) is supplied with the high signal from the first output port to the base so that the emitter and the collector are conducted;
When the fourth transistor (Q4) is turned on, the output current output from the collector of the third transistor (Q3) flows to the fourth transistor (Q4) to block flow to the controller;
Determining, by the controller, a failure of the gas detection sensor when the output current is not input from the conversion circuit unit;
And a step of notifying the outside of the notification unit by the control unit.

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