JP3697757B2

JP3697757B2 - Thermistor circuit monitoring device

Info

Publication number: JP3697757B2
Application number: JP27532795A
Authority: JP
Inventors: 秀樹山川; 光男横畑; 博之千田; 祥男赤松
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 1995-10-24
Filing date: 1995-10-24
Publication date: 2005-09-21
Anticipated expiration: 2015-10-24
Also published as: KR970022255A; CN1150633A; KR100201024B1; JPH09112912A; CN1138098C

Description

【０００１】
【発明の属する技術分野】
本発明は、ガス燃焼機器のサーミスタ回路監視装置に関するものである。
【０００２】
【従来の技術】
近年、ガス調理器の調理油過熱防止装置普及のため、より安価な過熱防止装置が必要となってきている。
【０００３】
従来の過熱防止装置は、センサーとして温度変化に対する抵抗値の変化が小さい、Ｂ定数が小さなサーミスタを使用して、抵抗値の変化を電圧に変換するための分圧抵抗を１本で検知していた。
【０００４】
【発明が解決しようとする課題】
しかし、より安価な過熱防止装置の必要から安価なサーミスタを使用すると、安価なサーミスタは一般にＢ定数が大きいため、温度変化に対する抵抗値の変化が大きく、使用温度範囲が０度から数百度とすると、抵抗値は数ＭΩから百数十Ωまで変化するので１本の分圧抵抗で広い温度範囲を検知しようとすると、高温または低温部で、著しく感度が悪化する。そこで、複数の分圧抵抗を切り換えることで感度の悪化を改善しようとすると、サーミスタの抵抗値が大きいときに第２の抵抗が断線した場合に、電圧監視手段の入力インピーダンスが小さいと、第１の電圧がグランド電位にまで下がらず、比較器による単純な比較のみでは、第２の抵抗が断線が検知できない。
【０００５】
また、スイッチング素子のロスによる電圧降下や、サーミスタのＢ定数のばらつきが大きい場合、サーミスタの抵抗値が大きいと、第１の抵抗の短絡によって第２の電圧が高くなっても、スイッチング素子のロスやサーミスタのばらつきによる電圧誤差範囲と重なってしまい、第１の抵抗の短絡が検知できない。
【０００６】
また、サーミスタのＢ定数のばらつきが大きい場合、第１の抵抗の断線によって第２の電圧が低くなっても、サーミスタのばらつきによる電圧誤差範囲と重なってしまい、第１の抵抗の断線が検知できない。
【０００７】
逆にばらつきが小さなものを使用すると、高価になる。
【０００８】
【課題を解決するための手段】
本発明は前記課題を解決するために、電源に接続されたスイッチング素子と、前記スイッチング素子をスイッチングさせるためのスイッチング手段と、前記スイッチング素子に直列に接続された第１の抵抗と、前記第１の抵抗に直列に接続され、他端をグランド電位に接続したサーミスタと、一端を前記第１の抵抗と前記サーミスタとの接続点に接続され、他端を前記電源に接続した第２の抵抗と、前記接続点に接続され前記接続点の信号を監視して、信号が予め決めておいた状態になるとガス通路に設けられた電磁弁を閉じる信号監視手段とを備え、前記スイッチング素子が非導通状態の前記接続点の第１の信号が所定の範囲にあり、且つ、前記スイッチング素子が導通状態の前記接続点の第２の信号との差が、所定の値以下であると、前記電磁弁を閉じる構成とした。
【０００９】
この構成により、第１の電圧の範囲と、第１の電圧と第２の電圧の差とをスイッチング素子のロスによる電圧降下や、サーミスタのＢ定数のばらつきによる電圧誤差範囲を無視できる値にすることで、第１の抵抗の短絡検知ができる。
【００１０】
【発明の実施の形態】
上記課題を解決するため、本発明の第１の手段として、電源に接続されたスイッチング素子と、そのスイッチング素子に直列に接続された第１の抵抗と、第１の抵抗とスイッチング素子が接続された端子と反対側の端子に接続され、他端を前記電源に接続された第２の抵抗と、第１の抵抗と第２の抵抗の結節点に接続され、他端をグランド電位に接続したサーミスタと、スイッチング素子をスイッチングさせるためのスイッチング手段と、第１の抵抗とサーミスタとの結節点に接続され、その結節点の電圧を監視して所定の電圧状態になるとガス通路に設けられた電磁弁を閉じる電圧監視手段により構成され、スイッチング素子が非導通状態での第１の抵抗とサーミスタとの接続点の第１の電圧が、所定の電圧範囲にあり、且つ、スイッチング素子が導通状態での第１の抵抗とサーミスタとの接続点の第２の電圧との差が、所定の電圧以下であると、電磁弁を閉じるようにした。
【００１１】
また、第２の手段として、第２の電圧が、所定の電圧範囲の時に、第１の電圧と第２の電圧との差が、所定の電圧以下であると、電磁弁を閉じるようにした。
【００１２】
また、第３の手段として、電源に接続されたスイッチング素子と、スイッチング素子に直列に接続された第１の抵抗と、第１の抵抗とスイッチング素子が接続された端子と反対側の端子に接続され、他端を電源に接続された第２の抵抗と、第１の抵抗と第２の抵抗との結節点に接続され、他端をグランド電位に接続したサーミスタと、スイッチング素子をスイッチングさせるためのスイッチング手段と、第１の抵抗とサーミスタとの結節点に接続され、その結節点の電圧を監視して、所定の電圧状態になると、ガス通路に設けられた電磁弁を閉じる電圧監視手段により構成され、スイッチング素子が非導通状態の第１の抵抗とサーミスタとの接続点の第１の電圧が、所定の電圧範囲の時に、スイッチング素子が導通状態での第１の抵抗とサーミスタとの接続点の第２の電圧が、所定の電圧以下であると、前記電磁弁を閉じるようにした。
【００１３】
また、第４の手段として、第１の電圧が、所定の電圧範囲の時に、第２の電圧の電圧が、所定の電圧以下であると、電磁弁を閉じるようにした。
【００１４】
本発明は上記した構成によって、第１の電圧の範囲と第１の電圧と第２の電圧との差をスイッチング素子のロスによる電圧降下や、サーミスタのＢ定数のばらつきによる電圧誤差範囲を無視できる値にすることで、第１の抵抗の短絡検知ができる。
【００１５】
また、第２の電圧を適切な範囲と第１の電圧と第２の電圧との差をサーミスタのＢ定数のばらつきによる電圧誤差範囲を無視できる値にすることで、第１の抵抗の断線検知ができる。
【００１６】
また、第１の電圧を電圧監視手段の入力インピーダンスが無視できる範囲にして、第２の電圧をサーミスタのＢ定数のばらつきによる電圧誤差範囲を無視できる値にすることで、第２の抵抗の断線検知ができる。
【００１７】
また、第２の電圧を電圧監視手段の入力インピーダンスが無視できる範囲にして、第１の電圧をサーミスタのＢ定数のばらつきによる電圧誤差範囲を無視できる値にすることで、第２の抵抗の断線検知ができる。
【００１８】
以下、本発明の実施の形態を図面に基づいて説明する。
図１は本発明のサーミスタ回路監視装置の一実施の形態の構成を示す図である。図１において、電源に接続されたスイッチング素子としてのトランジスタ１にはスイッチング手段５が接続され、そのトランジスタ１には、第１の抵抗２とサーミスタ４が直列に接続されている。更に、トランジスタ１と第１の抵抗２には、並列に第２の抵抗３が接続され、第１の抵抗２と第２の抵抗３とサーミスタ４の結節点には、電圧監視手段７が接続されている。スイッチング手段５は、所定の周期でトランジスタ１をオン、オフする。
【００１９】
電圧監視手段７の入力信号６は、サーミスタ４の抵抗値の変化とトランジスタ１のオン、オフに応じて変化する。電圧監視手段７は、入力信号６の状態に応じて、出力信号１０によりトランジスタ１１を制御し、電磁弁１２を開閉する。
【００２０】
抵抗８、抵抗９は、電圧監視手段７の入力抵抗を表している。
図２は、装置が正常に作動している場合に、サーミスタ４の抵抗値と入力信号６との特性図である。１３と１４は、トランジスタ１がオンの時、１５と１６はトランジスタ１がオフの時の特性で、１３と１４、及び、１５と１６の幅は、サーミスタ４やトランジスタ１の飽和電圧、及び、電圧監視手段７の入力抵抗のばらつきを含んだ場合の一例である。
【００２１】
図３は、第１の抵抗２が短絡した場合の図２と同様の特性図で、１７と１８はトランジスタ１がオンの時、１９と２０はトランジスタ１がオフの時の特性である。図２と図３の特性図は、範囲Ａの部分において、トランジスタ１がオンの時の入力信号６に差がある。従って、トランジスタ１がオフの時の入力信号６が範囲Ａにあるときに、トランジスタ１がオンの時とオフの時のそれぞれの入力信号６の差が通常の場合と異なる場合に出力信号１０によってトランジスタ１１をオフして電磁弁１２を閉弁するように電圧監視手段７の諸定数を決めることで、第１の抵抗２の短絡が検知できる。
【００２２】
図４は、第１の抵抗２または、トランジスタ１のエミッタまたはコレクタが断線した場合の図２と同様の特性図である。トランジスタ１がオンの時とオフの時の特性は重なってしまい、２１及び２２となる。図２と図４の特性図では、範囲Ｂの部分において、トランジスタ１がオンの時とオフの時の入力信号６の差に違いがある。従って、図４においてトランジスタ１がオンの時の入力信号６が範囲Ｂにあるときに、トランジスタ１がオンの時とオフの時のそれぞれの入力信号６の値の差が図２の時と異なった場合は、出力信号１０によってトランジスタ１１をオフして電磁弁１２を閉弁するように電圧監視手段７の諸定数を決めることで、第１の抵抗２または、トランジスタ１のエミッタかコレクタが断線した場合、安全にガスを遮断できる。
【００２３】
図５は、第２の抵抗３が断線した場合の図２と同様の特性図である。２３と２４は、トランジスタ１がオンの時、２５と２６は、トランジスタ１がオフの時の特性である。２５は、電圧監視手段７の入力抵抗８及び９が入力信号６の出力抵抗に対して無視できない場合で、２６は、電圧監視手段７の入力抵抗８及び９が入力信号６の出力抵抗に対して無視できる場合である。電圧監視手段７の入力抵抗８及び９が、入力信号６の出力抵抗に対して無視できない場合、図２と図５の特性図では、範囲Ｃの部分に、トランジスタ１がオフの時の入力信号６に差がある。従って、トランジスタ１がオフの時またはオンの時の入力信号６が範囲Ｃにあるときに、トランジスタ１がオンの時とオフの時のそれぞれの入力信号６の値が通常の状態と異なった場合は、出力信号１０によってトランジスタ１１をオフして電磁弁１２を閉弁するように電圧監視手段７の諸定数を決めることで、第１の抵抗２の短絡が検知できる。
【００２４】
図６は、トランジスタ１のエミッタとコレクタの間が短絡した場合の図２と同様の特性図である。トランジスタ１がオンの時とオフの時の差はなくなり、２７及び２８となる。図２と図５の特性図では、範囲Ｄの部分において、トランジスタ１がオンの時とオフの時の入力信号６の差に違いがある。従って、トランジスタ１がオンの時の入力信号６が範囲Ｄにあるときに、トランジスタ１がオンの時とオフの時のそれぞれの入力信号６の値の差が図２の時と異なった場合には、出力信号１０によってトランジスタ１１をオフして電磁弁１２を閉弁するように電圧監視手段７の諸定数を決めることで、トランジスタ１のエミッタ、コレクタ間の短絡が検知できる。
【００２５】
【発明の効果】
本発明のサーミスタ回路監視装置によれば、下記の効果がある。
【００２６】
（１）第１の電圧の範囲と第１の電圧と第２の電圧との差を、スイッチング素子のロスによる電圧降下やサーミスタのＢ定数のばらつきによる電圧誤差範囲を無視できる値にすることで、第１の抵抗の短絡検知ができるので、第１の抵抗が短絡しても不安全にならず、且つ、温度変化に対する抵抗値の変化が大きな、Ｂ定数が大きいサーミスタを精度良く使用できる。
【００２７】
（２）第２の電圧の範囲と第１の電圧と第２の電圧との差を、サーミスタのＢ定数のばらつきによる電圧誤差範囲を無視できる値にすることで、第１の抵抗が断線または、スイッチング素子が断線した場合に電磁弁を閉弁することで、不安全にならず、且つ、温度変化に対する抵抗値の変化が大きな、Ｂ定数が大きいサーミスタを精度良く使用できる。
【００２８】
（３）第１の電圧を電圧監視手段の入力インピーダンスが無視できる範囲にして、第２の電圧をサーミスタのＢ定数のばらつきによる電圧誤差範囲を無視できる値にすることで、第２の抵抗の断線検知ができるので、第２の抵抗が断線しても不安全にならず、且つ、温度変化に対する抵抗値の変化が大きな、Ｂ定数が大きいサーミスタを精度良く使用できる。
【００２９】
（４）第２の電圧を電圧監視手段の入力インピーダンスが無視できる範囲にして、第１の電圧をサーミスタのＢ定数のばらつきによる電圧誤差範囲を無視できる値にすることで、第２の抵抗の断線検知ができるので、第２の抵抗が断線しても不安全にならず、且つ、温度変化に対する抵抗値の変化が大きな、Ｂ定数が大きいサーミスタを精度良く使用できる。
【図面の簡単な説明】
【図１】本発明の一実施の形態のサーミスタ回路監視装置の構成を示す図
【図２】同サーミスタ回路監視装置のサーミスタの抵抗値と入力信号との関係を示す特性図
【図３】同サーミスタ回路監視装置において、第１の抵抗が短絡した場合の特性図
【図４】同サーミスタ回路監視装置において、第１の抵抗または、トランジスタ１のエミッタかコレクタが断線した場合の特性図
【図５】同サーミスタ回路監視装置において、第２の抵抗が断線した場合の特性図
【図６】同サーミスタ回路監視装置において、トランジスタ１のエミッタ、コレクタ間が短絡した場合の特性図
【符号の説明】
１、１１トランジスタ（スイッチング素子）
２第１の抵抗
３第２の抵抗
４サーミスタ
５スイッチング手段
７電圧監視手段
８、９抵抗
１２電磁弁[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermistor circuit monitoring device for gas combustion equipment.
[0002]
[Prior art]
In recent years, cheaper overheat prevention devices have become necessary for the spread of cooking oil overheat prevention devices for gas cookers.
[0003]
A conventional overheat prevention device uses a thermistor with a small resistance value change with respect to a temperature change as a sensor and a small B constant, and detects a voltage dividing resistor for converting the resistance value change into a voltage with a single resistor. It was.
[0004]
[Problems to be solved by the invention]
However, if an inexpensive thermistor is used due to the need for a cheaper overheat prevention device, an inexpensive thermistor generally has a large B constant. Since the resistance value varies from several MΩ to hundreds of Ω, if an attempt is made to detect a wide temperature range with a single voltage dividing resistor, the sensitivity is significantly deteriorated at high or low temperature portions. In order to improve the deterioration of sensitivity by switching a plurality of voltage dividing resistors, if the second resistor is disconnected when the resistance value of the thermistor is large and the input impedance of the voltage monitoring means is small, the first The voltage of the second resistor does not drop to the ground potential, and the disconnection of the second resistor cannot be detected only by simple comparison by the comparator.
[0005]
In addition, when the voltage drop due to the loss of the switching element or the variation of the B constant of the thermistor is large, if the resistance value of the thermistor is large, even if the second voltage increases due to the short circuit of the first resistor, the loss of the switching element And a voltage error range due to variations in thermistors overlap, and a short circuit of the first resistor cannot be detected.
[0006]
Also, when the B constant of the thermistor is large, even if the second voltage is lowered due to the disconnection of the first resistor, it overlaps with the voltage error range due to the thermistor variation, and the disconnection of the first resistor cannot be detected. .
[0007]
On the other hand, it is expensive to use one with small variations.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a switching element connected to a power source, switching means for switching the switching element, a first resistor connected in series to the switching element, and the first A thermistor connected in series to the first resistor, the other end connected to the ground potential, one end connected to a connection point between the first resistor and the thermistor, and the other end connected to the power source. And a signal monitoring means for monitoring the signal of the connection point connected to the connection point and closing a solenoid valve provided in the gas passage when the signal reaches a predetermined state, and the switching element is non-conductive When the first signal at the connection point in the state is in a predetermined range and the difference from the second signal at the connection point in the conductive state is equal to or less than a predetermined value, It was closing an electromagnetic valve.
[0009]
With this configuration, the first voltage range and the difference between the first voltage and the second voltage are set to values that can ignore the voltage drop due to the loss of the switching element and the voltage error range due to variation in the B constant of the thermistor. Thus, the short circuit of the first resistor can be detected.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In order to solve the above problems, as a first means of the present invention, a switching element connected to a power source, a first resistor connected in series to the switching element, a first resistor and the switching element are connected. A second resistor connected to the power source, the other end connected to the node of the first resistor and the second resistor, and the other end connected to the ground potential. The thermistor, the switching means for switching the switching element, and the first resistor and the thermistor are connected to the nodal point. When the voltage at the nodal point is monitored and becomes a predetermined voltage state, the electromagnetic provided in the gas passage The first voltage at the connection point between the first resistor and the thermistor when the switching element is in a non-conductive state is in a predetermined voltage range, and is configured by voltage monitoring means for closing the valve. Element is the difference between the second voltage at the node between the first resistor and the thermistor in conducting state, is not more than a predetermined voltage, and to close the solenoid valve.
[0011]
As a second means, when the second voltage is within a predetermined voltage range, the electromagnetic valve is closed if the difference between the first voltage and the second voltage is equal to or less than the predetermined voltage. .
[0012]
As a third means, a switching element connected to the power source, a first resistor connected in series to the switching element, and a terminal opposite to the terminal connected to the first resistor and the switching element are connected. For switching the switching element, the second resistor having the other end connected to the power source, the thermistor having the other end connected to the ground potential, and the node connected to the ground between the first resistor and the second resistor. Switching means, and a voltage monitoring means that is connected to a node between the first resistor and the thermistor, monitors the voltage at the node, and closes an electromagnetic valve provided in the gas passage when a predetermined voltage state is reached. When the first voltage at the connection point between the first resistor and the thermistor in which the switching element is in a non-conductive state is within a predetermined voltage range, the first resistor and the circuit in which the switching element is in a conductive state. A second voltage at the node between the static is, if it is below a predetermined voltage, and to close the solenoid valve.
[0013]
As a fourth means, when the first voltage is within a predetermined voltage range, the electromagnetic valve is closed when the second voltage is equal to or lower than the predetermined voltage.
[0014]
According to the present invention, the difference between the first voltage range and the first voltage and the second voltage can be neglected by the voltage drop due to the loss of the switching element and the voltage error range due to variations in the B constant of the thermistor. By setting the value, it is possible to detect a short circuit of the first resistor.
[0015]
In addition, the disconnection of the first resistor is detected by setting the difference between the second voltage to an appropriate range and the difference between the first voltage and the second voltage so that the voltage error range due to variation in the B constant of the thermistor can be ignored. Can do.
[0016]
Further, the first resistor is set in a range where the input impedance of the voltage monitoring means can be ignored, and the second voltage is set in a value in which the voltage error range due to variation in the B constant of the thermistor can be ignored, thereby disconnecting the second resistor. Can be detected.
[0017]
In addition, the second resistor is set to a range in which the input impedance of the voltage monitoring unit can be ignored, and the first voltage is set to a value in which the voltage error range due to variation in the B constant of the thermistor can be ignored, thereby disconnecting the second resistor. Can be detected.
[0018]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing the configuration of an embodiment of the thermistor circuit monitoring device of the present invention. In FIG. 1, a switching means 5 is connected to a transistor 1 as a switching element connected to a power source, and a first resistor 2 and a thermistor 4 are connected in series to the transistor 1. Further, a second resistor 3 is connected in parallel to the transistor 1 and the first resistor 2, and a voltage monitoring means 7 is connected to a node between the first resistor 2, the second resistor 3 and the thermistor 4. Has been. The switching means 5 turns on and off the transistor 1 at a predetermined cycle.
[0019]
The input signal 6 of the voltage monitoring means 7 changes according to the change in the resistance value of the thermistor 4 and the on / off state of the transistor 1. The voltage monitoring means 7 controls the transistor 11 with the output signal 10 according to the state of the input signal 6 to open and close the electromagnetic valve 12.
[0020]
Resistors 8 and 9 represent the input resistance of the voltage monitoring means 7.
FIG. 2 is a characteristic diagram of the resistance value of the thermistor 4 and the input signal 6 when the apparatus is operating normally. 13 and 14 are characteristics when the transistor 1 is on, 15 and 16 are characteristics when the transistor 1 is off, and the widths of 13 and 14 and 15 and 16 are the saturation voltage of the thermistor 4 and the transistor 1, and This is an example in the case of including variations in the input resistance of the voltage monitoring means 7.
[0021]
FIG. 3 is a characteristic diagram similar to FIG. 2 when the first resistor 2 is short-circuited. 17 and 18 are characteristics when the transistor 1 is on, and 19 and 20 are characteristics when the transistor 1 is off. 2 and 3, there is a difference in the input signal 6 when the transistor 1 is on in the range A. Therefore, when the input signal 6 when the transistor 1 is off is in the range A, the difference between the input signals 6 when the transistor 1 is on and when the transistor 1 is off is different from the normal case by the output signal 10. By determining the constants of the voltage monitoring means 7 so that the transistor 11 is turned off and the electromagnetic valve 12 is closed, a short circuit of the first resistor 2 can be detected.
[0022]
FIG. 4 is a characteristic diagram similar to FIG. 2 when the first resistor 2 or the emitter or collector of the transistor 1 is disconnected. The characteristics when the transistor 1 is turned on and when the transistor 1 is turned off are overlapped to be 21 and 22. In the characteristic diagrams of FIG. 2 and FIG. 4, in the range B, there is a difference in the difference between the input signals 6 when the transistor 1 is on and off. Therefore, in FIG. 4, when the input signal 6 when the transistor 1 is on is in the range B, the difference between the values of the input signal 6 when the transistor 1 is on and when the transistor 1 is off is different from that in FIG. In this case, the first resistor 2 or the emitter or collector of the transistor 1 is disconnected by determining various constants of the voltage monitoring means 7 so that the transistor 11 is turned off by the output signal 10 and the solenoid valve 12 is closed. If you do, you can safely shut off the gas.
[0023]
FIG. 5 is a characteristic diagram similar to FIG. 2 when the second resistor 3 is disconnected. Reference numerals 23 and 24 are characteristics when the transistor 1 is on, and reference numerals 25 and 26 are characteristics when the transistor 1 is off. Reference numeral 25 denotes a case where the input resistances 8 and 9 of the voltage monitoring unit 7 cannot be ignored with respect to the output resistance of the input signal 6. Reference numeral 26 denotes a case where the input resistances 8 and 9 of the voltage monitoring unit 7 Can be ignored. When the input resistors 8 and 9 of the voltage monitoring means 7 cannot be ignored with respect to the output resistance of the input signal 6, in the characteristic diagrams of FIGS. There is a difference in 6. Therefore, when the input signal 6 when the transistor 1 is off or when it is on is in the range C, the value of the input signal 6 when the transistor 1 is on and when the transistor 1 is off is different from the normal state. Can detect a short circuit of the first resistor 2 by determining various constants of the voltage monitoring means 7 so that the transistor 11 is turned off and the solenoid valve 12 is closed by the output signal 10.
[0024]
FIG. 6 is a characteristic diagram similar to FIG. 2 when the emitter and collector of the transistor 1 are short-circuited. The difference between when the transistor 1 is on and when it is off is 27 and 28. In the characteristic diagrams of FIG. 2 and FIG. 5, in the range D, there is a difference in the difference of the input signal 6 when the transistor 1 is on and off. Therefore, when the input signal 6 when the transistor 1 is on is in the range D, the difference between the values of the input signal 6 when the transistor 1 is on and when the transistor 1 is off is different from that in FIG. Can determine the short circuit between the emitter and collector of the transistor 1 by determining various constants of the voltage monitoring means 7 so that the transistor 11 is turned off and the solenoid valve 12 is closed by the output signal 10.
[0025]
【The invention's effect】
The thermistor circuit monitoring device of the present invention has the following effects.
[0026]
(1) By setting the difference between the first voltage range and the first voltage and the second voltage to a value in which the voltage error range due to the voltage drop due to the loss of the switching element and the variation of the B constant of the thermistor can be ignored. Since the short circuit of the first resistor can be detected, it is not unsafe even if the first resistor is short circuited, and a thermistor having a large change in resistance value with respect to a temperature change and a large B constant can be used with high accuracy.
[0027]
(2) The difference between the second voltage range and the first voltage and the second voltage is set to a value in which the voltage error range due to variation in the B constant of the thermistor can be ignored, so that the first resistor is disconnected or By closing the solenoid valve when the switching element is disconnected, a thermistor that is not unsafe, has a large resistance value change with respect to a temperature change, and has a large B constant can be used with high accuracy.
[0028]
(3) By setting the first voltage within a range where the input impedance of the voltage monitoring means can be ignored, and setting the second voltage at a value where the voltage error range due to variations in the B constant of the thermistor can be ignored, the second resistor Since the disconnection can be detected, it is not unsafe even if the second resistor is disconnected, and a thermistor having a large resistance value change with respect to a temperature change and a large B constant can be used with high accuracy.
[0029]
(4) By setting the second voltage within a range where the input impedance of the voltage monitoring means can be ignored, and setting the first voltage at a value where the voltage error range due to variation in the B constant of the thermistor can be ignored, the second resistor Since the disconnection can be detected, it is not unsafe even if the second resistor is disconnected, and a thermistor having a large resistance value change with respect to a temperature change and a large B constant can be used with high accuracy.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a thermistor circuit monitoring device according to an embodiment of the present invention. FIG. 2 is a characteristic diagram illustrating a relationship between a resistance value of the thermistor of the thermistor circuit monitoring device and an input signal. FIG. 4 is a characteristic diagram when the first resistor is short-circuited in the thermistor circuit monitoring device. FIG. 4 is a characteristic diagram when the first resistor or the emitter or collector of the transistor 1 is disconnected in the thermistor circuit monitoring device. ] Characteristic diagram when the second resistor is disconnected in the thermistor circuit monitoring device. [FIG. 6] Characteristic diagram when the emitter and collector of the transistor 1 are short-circuited in the thermistor circuit monitoring device.
1,11 Transistor (switching element)
2 First resistor 3 Second resistor 4 Thermistor 5 Switching means 7 Voltage monitoring means 8, 9 Resistance 12 Solenoid valve

Claims

A switching element connected to a power source, switching means for switching the switching element, a first resistor connected in series to the switching element, and a second resistor connected in series to the first resistor. A thermistor connected to the ground potential; one end connected to the connection point between the first resistor and the thermistor; the other end connected to the power supply; and the connection point connected to the connection point. A signal monitoring means for monitoring the signal and closing an electromagnetic valve provided in the gas passage when the signal is in a predetermined state, wherein the first signal at the connection point where the switching element is non-conductive is The solenoid valve is closed when the difference between the second signal at the connection point in the predetermined range and the switching element in the conductive state is equal to or smaller than a predetermined value. Mista circuit monitoring device.

2. The thermistor circuit monitoring device according to claim 1, wherein when the second signal is within a predetermined range, the electromagnetic valve is closed when a difference between the first signal and the second signal is equal to or less than a predetermined value. A thermistor circuit monitoring device.

A switching element connected to a power source, switching means for switching the switching element, a first resistor connected in series to the switching element, and a second resistor connected in series to the first resistor. A thermistor connected to the ground potential, a second resistor connected to the connection point between the first resistor and the thermistor and the other end connected to the power supply, and a signal at the connection point connected to the connection point When the signal is in a predetermined state, the signal monitoring means closes the electromagnetic valve provided in the gas passage, and the first signal at the connection point when the switching element is in the non-conductive state The thermistor is characterized in that when the second signal at the connection point where the switching element is in a conductive state is not more than a predetermined value when Road monitoring equipment.

4. The thermistor circuit monitoring device according to claim 3, wherein when the first signal is within a predetermined range, the electromagnetic valve is closed when the second signal is not more than a predetermined value. .