JP3869474B2

JP3869474B2 - Temperature control circuit

Info

Publication number: JP3869474B2
Application number: JP22819794A
Authority: JP
Inventors: 勲栗原
Original assignee: Tottori Sanyo Electric Co Ltd; Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 1994-09-22
Filing date: 1994-09-22
Publication date: 2007-01-17
Anticipated expiration: 2022-01-17
Also published as: JPH0896928A

Description

【０００１】
【産業上の利用分野】
本発明は電気カーペット、電気毛布等の電気採暖具に最適な温度制御回路に関する。
【０００２】
【従来の技術】
電気カーペットのような電気採暖具は、例えば特開平４−６４８２８号公報に見られるように電熱線（Ｈ）と感熱線（１１）と該感熱線の感熱層（１ａ）（１ｂ）の抵抗率の変化を検出して前記電熱線の制御を行う温度制御回路により構成しており、何らかの理由により電熱線が異常温度上昇した場合には、導線（２ａ）または（２ｂ）に接続した演算増幅器（ＯＰ１）或いは（ＯＰ２）がハイレベル電圧を出力し、ＳＣＲがオンとなって抵抗（Ｒ３）を発熱させ、ヒューズ（Ｆ）を溶断させる。
【０００３】
【発明が解決しようとする課題】
ところが、前述の先行技術に見られるような導線と感熱層は採暖具の広範囲にわたって配設しており、どの部分で電熱線が異常発熱するのか特定されず、また同時に複数箇所で異常過熱を生ずることもあり得る。
【０００４】
また、導線が複数箇所で断線した場合には、温度検知電圧が規定の電圧にならないため、温度制御電圧や安全回路が満足に作動せず、火災等の危険な状態になるという欠点があった。
【０００６】
本発明は、発熱体の複数箇所で同時に異常過熱が発生して複数箇所で発熱線と短絡用導体が短絡したり、短絡用導体の断線が生じた場合であっても、確実に温度ヒューズを溶断したり、リレー駆動を停止して発熱線が連続発熱するのを防止するものである。
【０００７】
【課題を解決するための手段】
本発明は、発熱体と、該発熱体に直列接続した電力制御素子と、前記発熱体に直列接続した温度ヒューズと、前記発熱体の温度を検出し前記電力制御素子を開閉して前記発熱体を所定温度に制御するものにおいて、前記発熱体は、発熱線と短絡用導体と該短絡用導体と発熱線間に介在し所定温度以上で溶融する熱溶融層と前記短絡用導体の外周を被う絶縁層で構成し、前記発熱体への通電を遮断すべく設けた前記温度ヒューズには、その近傍に配置した第１、第２加熱抵抗に電流を流して、その発熱により加熱溶断する構成とし、交流電源の両端間に、第１ダイオードと該ダイオードとは逆方向の第２ダイオードと前記第１加熱抵抗と前記第１ダイオードと逆方向の第３ダイオードを直列接続し、前記第２ダイオードに、第２加熱抵抗と前記第１ダイオードと同方向の第４ダイオードと前記短絡用導体の直列回路を並列接続したものである。
【０００８】
また、前記第１ダイオードと第２加熱抵抗と第４ダイオードと短絡用導体の直列回路を介して、前記第１加熱抵抗と第３ダイオードの接続点から前記電力制御素子の開閉に必要な電源を供給するものである。
【０００９】
【作用】
本発明は、交流電源の両端間に、第１ダイオードと該ダイオードとは逆方向の第２ダイオードと温度ヒューズの近くに設けた第１加熱抵抗と前記第１ダイオードと逆方向の第３ダイオードを直列接続し、前記第２ダイオードに、第２加熱抵抗と前記第１ダイオードと同方向の第４ダイオードと前記短絡用導体の直列回路を並列接続したことにより、発熱線と短絡用導体の複数箇所で異常過熱を生じ、複数箇所で短絡した場合には、第２加熱抵抗を発熱させて温度ヒューズを溶断し、発熱線の連続発熱を防止する。
【００１０】
また、発熱線の発熱を制御する電力制御素子の開閉に必要な電力は、第１ダイオードと第２加熱抵抗と第４ダイオードと短絡用導体の直列回路を介して、第１加熱抵抗と第３ダイオードとの接続点から供給することにより、短絡用導体の断線時には電力制御素子の開閉に必要な電力が得られず発熱線の発熱が停止する。
【００１１】
【実施例】
本発明の実施例を図面に基づいて説明する。図１は本発明の温度制御回路の一実施例を示す回路図、図２は同じく発熱体の説明図、図３は温度ヒューズ組立体の平面図である。
【００１２】
（１）、（２）は電気カーペットの生地（図示せず）に蛇行状に配置した線状の第１、第２の発熱体で、図２に示すようにテトロン芯（３）、（４）と該テトロン芯の外周に巻線した第１、第２の発熱線（５）、（６）と該発熱線の外周を被い所定温度以上で溶融する第１、第２の熱溶融層（７）、（８）と該熱溶融層の外周に巻線した第１、第２の短絡用導体（９）、（１０）と該短絡用導体の外周を被う絶縁層（１１）、（１２）とから構成している。（１３）は交流電源である。
【００１３】
（１４）は前記第１、第２の発熱線（５）、（６）の一端と接続した２つの接点（１５）、（１６）と中間の接点（１７）を有する暖房面積切換スイッチ、（１８）は前記接点（１７）と交流電源（１３）の電極（Ａ）間に接続し前記発熱線（５）、（６）の発熱を制御する電力制御素子（以下リレー接点とする）で、後述するリレーにより開閉する。
【００１４】
前記第１、第２の発熱線（５）、（６）の他端は、それぞれを交流電源の電極（Ｂ）に接続し、前記第１、第２の短絡用導体（９）、（１０）の一端は互いに接続してそれぞれが直列接続されている。
【００１５】
（１９）は前記発熱体（１）、（２）の近傍に配置した温度検知線（図示せず）により設定温度と器具温度とを比較し発熱体を制御する制御回路で、設定温度に達した時には出力端子（Ｐ₀）を「Ｌ」出力とし、設定温度に達するまでは出力端子（Ｐ₀）を「Ｈ」出力にする。
【００１６】
（２０）は前記第１、第２電熱線（５）、（６）の他端と交流電源（１３）の電極（Ｂ）間に直列に介挿した温度ヒューズで、図に示すようにその両側には密着して第１、第２加熱抵抗（２１）、（２２）を配置しており、これらは温度ヒューズ組立体（２３）を構成する。
【００１７】
（２４）はアノードを交流電源（１３）の電極（Ａ）に接続しカソードを第２加熱抵抗（２２）に接続した第１ダイオード、（２５）はアノードを第１加熱抵抗（２１）に接続しカソードを前記第１ダイオード（２４）のカソードに接続して該第１ダイオードと逆方向に配置した第２ダイオード、（２６）はアノードを交流電源（１３）の電極（Ｂ）に接続しカソードを第１加熱抵抗（２１）に接続した第３ダイオード、（２７）はアノードを第２加熱抵抗（２２）に接続しカソードを前記第２の短絡用導体（１０）の他端に接続した第４ダイオードである。
【００１８】
前記第１の短絡用導体（９）の他端は前記第２ダイオード（２５）と第１加熱抵抗（２１）の接続部に接続している。
【００１９】
従って、交流電源の両端間に、第１ダイオード（２４）と該ダイオードとは逆方向の第２ダイオード（２５）と前記第１加熱抵抗（２１）と前記第１ダイオード（２４）と逆方向の第３ダイオード（２６）を直列接続し、前記第２ダイオード（２５）に、第２加熱抵抗（２２）と第１ダイオード（２４）と同方向の第４ダイオード（２７）と前記第１、第２の短絡用導体（９）（１０）の直列回路を並列接続している。
【００２０】
（２８）は前記第２加熱抵抗（２２）と第４ダイオード（２７）の接続部と交流電源（１３）の電極（Ｂ）との間に接続したＳＣＲで、前記第１ダイオード（２４）と同方向に配置している。
【００２１】
（２９）はアノードを前記リレー接点（１８）と暖房面積切換スイッチ（１４）の接続部に接続した第５ダイオード、（３０）は前記第５ダイオード（２９）のカソードに接続した抵抗、（３１）は前記抵抗（３０）に直列接続した第６ダイオード、（３２）は前記第６ダイオード（３１）に接続したコンデンサ、（３３）は前記第６ダイオード（３１）とコンデンサ（３２）との接続部と前記ＳＣＲ（２８）のゲートに接続したゲート回路、（３４）は前記第１加熱抵抗（２１）と第３ダイオード（２６）の接続部に接続したリレー（３５）の電源回路で、降圧抵抗（３６）と直流変換用ダイオード（３７）の直列回路（３８）とから構成している。（３９）は前記電源回路（３４）に直列接続したトランジスタで、そのベースを前記制御回路（１９）の出力端子（Ｐ₀）に接続している。（４０）は抵抗である。
【００２２】
（４１）は前記抵抗（３０）と第６ダイオード（３１）との接続部とトランジスタ（３９）のコレクタ間に接続した第７ダイオードである。（４２）は電源スイッチである。
【００２３】
次に動作について述べる。暖房面積切換スイッチ（１４）はその接点（１７）を接点（１５）に接続した場合には第１の発熱体（５）のみが発熱して例えば左側半分が発熱し、接点（１６）に接続した場合には第２の発熱体（６）のみが発熱して例えば右側半分が発熱し、両方の接点（１５）、（１６）に接続した場合にはそれぞれの発熱体（５）、（６）が発熱して全面加熱するようになされている。
【００２４】
今、暖房面積切換スイッチ（１４）を切り換えて第１の発熱体（５）のみを発熱するように設定した場合について述べる。電源スイッチ（４２）を閉じて通電を開始すると、始めは制御回路（１９）にて設定された設定温度に対してカーペット本体の温度が低いために制御回路（１９）の出力端子（Ｐ0）は「Ｈ」出力となりトランジスタ（３９）をオン状態にしてリレー（３５）を駆動してリレー接点（１８）をオンにする。
【００２５】
即ち、逆方向の半波において、交流電源（１３）の電極（Ａ）−第１ダイオード（２４）−第２加熱抵抗（２２）−第４ダイオード（２７）−第１、第２の短絡用導体（９）、（１０）−第１加熱抵抗（２１）の経路にて第３ダイオード（２６）間の両端電圧が前記リレー（３５）に印加される。
【００２６】
リレー接点（１８）のオンに伴ない交流電源（１３）の電極（Ａ）−リレー接点（１８）−暖房面積切換スイッチ（１４）−第１の発熱線（５）−交流電源（１３）の電極（Ｂ）の経路及びその逆方向の経路にて第１の発熱線（５）が発熱する。
【００２７】
やがて、カーペット本体の温度が上昇して設定温度に達すると、制御回路（１９）の出力端子（Ｐ０）が「Ｌ」になるため、トランジスタ（３９）がオフしリレー（３５）の駆動が停止してリレー接点（１８）がオフし第１の発熱線（５）への通電を停止する。
【００２８】
その後、カーペット本体の温度が低下し設定温度の許容温度幅を外れた温度まで低下すると制御回路（１９）の出力端子（Ｐ₀）が「Ｈ」となって前述と同様にリレー接点（１８）をオンにして再び第１の発熱線（５）に通電しカーペット本体を加熱する。
【００２９】
もし、制御回路（１９）の出力端子（Ｐ₀）の出力が「Ｌ」となってリレー（３５）の駆動を停止しリレー接点（１８）をオフして第１の発熱体（１）の発熱線（５）を停止するように作動しているにも拘らずリレー接点（１８）が経年変化等によって溶着している場合には、前述のようにトランジスタ（３９）がオフしているため、リレー接点（１８）−第５ダイオード（２９）−抵抗（３０）−第６ダイオード（３１）の経路によりゲート回路（３３）にてＳＣＲ（２８）をトリガーして、第１ダイオード（２４）−第２加熱抵抗（２２）−ＳＣＲ（２８）の経路により、温度ヒューズ（２０）を溶断し第１の発熱線（５）への通電を停止する。
【００３０】
かくして、第１の発熱線（５）の発熱動作中において、何らかの理由により異常過熱を生じて図１に示す（ａ）点で第１の発熱線（５）と第１の短絡用導体（９）が短絡した場合は、交流電源（１３）の電極（Ｂ）−温度ヒューズ（２０）−第３ダイオード（２６）−第１加熱抵抗（２１）−第１の短絡用導体（９）−短絡点（ａ）−暖房面積切換スイッチ（１４）ーリレー接点（１８）−交流電源（１３）の電極（Ａ）の経路にて第１加熱抵抗（２１）が発熱して温度ヒューズ（２０）を溶断する。
【００３１】
（ｂ）点で短絡した場合は、交流電源（１３）の電極（Ａ）−第１ダイオード（２４）−第２加熱抵抗（２２）−第４ダイオード（２７）−第１、第２の短絡用導体（９）、（１０）−短絡点（ｂ）−交流電源（１３）の電極（Ｂ）の経路にて第２加熱抵抗（２２）が発熱して温度ヒューズ（２０）を溶断する。
【００３２】
ここで、仮に（ａ）点と（ｂ）点の２箇所で同時に異常が生じて短絡した場合には、交流電源（１３）の電極（Ｂ）−温度ヒューズ（２０）−短絡点（ｂ）−第２ダイオード（２５）−第２加熱抵抗（２２）−第４ダイオード（２７）−第２の短絡用導体（１０）−短絡点（ａ）−暖房面積切換スイッチ（１４）−電極（Ａ）の経路にて第２加熱抵抗（２２）が発熱して温度ヒューズ（２０）を溶断する。
【００３３】
又、暖房面積切換スイッチ（１４）を切り換えて第２の発熱体（６）のみを発熱するように設定した場合の異常過熱時においても前述と同様な動作を行うことができ、仮に（ｃ）点で短絡した場合は、第１加熱抵抗（２１）が発熱し、（ｄ）点で短絡した場合は、第２加熱抵抗（２２）が発熱して各々温度ヒューズ（２０）を溶断する。（ｃ）点と（ｄ）点が同時に短絡した場合には、交流電源（１３）の電極（Ａ）−第１ダイオード（２４）−第２加熱抵抗（２２）−第４ダイオード（２７）−短絡点（ｄ）−温度ヒューズ（２０）−交流電源（１３）の電極（Ｂ）の経路にて第２加熱抵抗（２２）が発熱し、温度ヒューズ（２０）を溶断する。
【００３４】
かくして、第１或は第２の発熱体（１）、（２）の発熱動作中、或は発熱動作開始時に第１或は第２の短絡用導体（９）、（１０）の一部で断線した場合は、前記第１と第２の短絡用導体（９）、（１０）が直列接続されているため、どの短絡用導体が断線した場合であってもリレー（３５）の電源回路（３４）側に電圧が印加されず、仮に制御回路（１９）の出力端子（Ｐ₀）が「Ｈ」になってもリレー（３５）が駆動せず発熱線（５）或は（６）への通電が停止する。
【００３５】
【発明の効果】
以上の様に本発明は、発熱線と短絡用導体の複数箇所で異常過熱を生じて該発熱線と短絡用導体が複数箇所で短絡した場合であっても確実に第１、第２加熱抵抗のそれぞれが発熱し温度ヒューズが溶断して発熱線の連続発熱を防止する。
【００３６】
また、短絡用導体と加熱抵抗の直列回路を介して電力制御素子に電源を供給することで、短絡用導体の断線時には、電力制御素子の開閉に必要な電源が供給されず、発熱線への電流が遮断されて即時に発熱が停止する。
【図面の簡単な説明】
【図１】本発明の温度制御回路の一実施例を示す回路図である。
【図２】同じく発熱体の説明図である。
【図３】温度ヒューズ組立体の平面図である。
【符号の説明】
１第１の発熱体
２第２の発熱体
５第１の発熱線
６第２の発熱線
９第１の短絡用導体
１０第２の短絡用導体
１３交流電源
１８電力制御素子（リレー接点）
１９制御回路
２０温度ヒューズ
２１第１加熱抵抗
２２第２加熱抵抗
２４第１ダイオード
２５第２ダイオード
２６第３ダイオード
２７第４ダイオード[0001]
[Industrial application fields]
The present invention relates to a temperature control circuit optimum for an electric warming tool such as an electric carpet and an electric blanket.
[0002]
[Prior art]
As shown in, for example, Japanese Patent Laid-Open No. 4-64828, an electric warming tool such as an electric carpet has a resistivity of a heating wire (H), a heat sensitive wire (11), and a heat sensitive layer (1a) (1b) of the heat sensitive wire. Is detected by the temperature control circuit that controls the heating wire. If the heating wire rises abnormally for some reason, an operational amplifier (2a) or (2b) connected to the operational amplifier ( OP1) or (OP2) outputs a high level voltage, SCR is exothermed resistor turned on (R3), Ru is blown fuses (F).
[0003]
[Problems to be solved by the invention]
However, the conductive wire and the heat-sensitive layer found in the above-mentioned prior art are arranged over a wide range of the heating device, and it is not specified in which part the heating wire abnormally generates heat, and at the same time, abnormal heating occurs in a plurality of locations. It can happen.
[0004]
In addition, when the conducting wire is disconnected at multiple locations , the temperature detection voltage does not become the specified voltage, so the temperature control voltage and safety circuit do not operate satisfactorily, leading to a dangerous state such as a fire. .
[0006]
The present invention is, at a plurality of locations of heating elements simultaneously abnormal overheating occurs Ri shorting member with the heating wire at a plurality of locations are short-circuited, even when the disconnection of the shorting member occurs, ensure thermal fuse Or the relay drive is stopped to prevent the heating wire from continuously generating heat.
[0007]
[Means for Solving the Problems]
The present invention relates to a heating element, a power control element connected in series to the heating element, a temperature fuse connected in series to the heating element, and detecting the temperature of the heating element to open and close the power control element to open the heating element. The heating element includes a heating wire, a short-circuit conductor, a thermal melting layer interposed between the short-circuit conductor and the heating wire, and a periphery of the short-circuit conductor. A structure in which a current is passed through the first and second heating resistors arranged in the vicinity of the temperature fuse provided by an insulating layer and provided to cut off the power supply to the heating element, and is heated and melted by the generated heat. A first diode, a second diode in a direction opposite to the diode, the first heating resistor, and a third diode in the direction opposite to the first diode are connected in series between both ends of the AC power source, and the second diode And the second heating resistor and the A series circuit of a diode and the same direction of the fourth diode the shorting member is obtained by parallel connection.
[0008]
In addition, a power supply necessary for opening and closing the power control element is connected from a connection point of the first heating resistor and the third diode through a series circuit of the first diode, the second heating resistor, the fourth diode, and a short-circuiting conductor. To supply.
[0009]
[Action]
According to the present invention, a first diode, a second diode opposite to the diode, a first heating resistor provided near the temperature fuse, and a third diode opposite to the first diode are provided between both ends of the AC power source. connected in series, the second diode, by a series circuit of a fourth diode and the short-circuit conductor of the second heating resistor first diode and the same direction are connected in parallel, a plurality of locations of the heating wire and the shorting member in cause overheating, when it is short-circuited at a plurality of locations, exothermed second heating resistor to blow the thermal fuse to prevent continuous heating of the heating wire.
[0010]
In addition, the power required for opening and closing the power control element that controls the heat generation of the heating wire is supplied to the first heating resistor, the third heating resistor, the third heating resistor, the fourth diode, and the shorting conductor through a series circuit . By supplying from the connection point with the diode, when the short-circuiting conductor is disconnected, the power necessary for opening and closing the power control element cannot be obtained, and the heat generation of the heating line stops.
[0011]
【Example】
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of the temperature control circuit of the present invention, FIG. 2 is an explanatory view of the heating element, and FIG. 3 is a plan view of the thermal fuse assembly.
[0012]
(1) and (2) are linear first and second heating elements arranged in a meandering manner on a fabric (not shown) of an electric carpet. Tetron cores (3) and (4) as shown in FIG. ) And the first and second heating lines (5) and (6) wound around the outer periphery of the Tetron core and the first and second heat-melting layers covering the outer periphery of the heating line and melting at a predetermined temperature or higher. (7), (8) and the first and second short-circuit conductors (9) and (10) wound around the outer periphery of the heat-melting layer, and the insulating layer (11) covering the outer periphery of the short-circuit conductor, (12). (13) is an AC power source.
[0013]
(14) is a heating area changeover switch having two contacts (15), (16) and an intermediate contact (17) connected to one end of the first and second heating wires (5), (6); 18) is a power control element (hereinafter referred to as a relay contact) connected between the contact (17) and the electrode (A) of the AC power source (13) and controlling the heat generation of the heating wires (5) and (6). It is opened and closed by a relay described later.
[0014]
The other ends of the first and second heating wires (5) and (6) are respectively connected to electrodes (B) of an AC power source, and the first and second short-circuiting conductors (9) and (10 ) Are connected to each other in series.
[0015]
(19) is a control circuit that controls a heating element by comparing a set temperature with an appliance temperature by means of a temperature detection line (not shown) arranged in the vicinity of the heating elements (1) and (2). was when the output terminal (P ₀₎ and "L" output, to the output terminal until it reaches the set temperature (P ₀₎ in the "H" output.
[0016]
(20) is a thermal fuse inserted in series between the other ends of the first and second heating wires (5) and (6) and the electrode (B) of the AC power source (13), as shown in the figure. First and second heating resistors (21) and (22) are arranged in close contact with both sides, and constitute a thermal fuse assembly (23).
[0017]
(24) is a first diode in which the anode is connected to the electrode (A) of the AC power source (13) and the cathode is connected to the second heating resistor (22), and (25) is an anode connected to the first heating resistor (21). And a second diode (26) connected to the cathode of the first diode (24) and arranged in the opposite direction to the first diode, and (26) connected to the electrode (B) of the AC power source (13). A third diode connected to the first heating resistor (21), and (27) a second diode having an anode connected to the second heating resistor (22) and a cathode connected to the other end of the second short-circuiting conductor (10). 4 diodes.
[0018]
The other end of the first short-circuit conductor (9) is connected to a connection portion between the second diode (25) and the first heating resistor (21).
[0019]
Therefore, between the both ends of the AC power source, the first diode (24) , the second diode (25) in the opposite direction to the diode, the first heating resistor (21), and the first diode (24) in the opposite direction. A third diode (26) is connected in series, and the second diode (25) is connected to a fourth diode (27) in the same direction as the second heating resistor (22) and the first diode (24) , and the first and second diodes . A series circuit of two shorting conductors (9) and (10) is connected in parallel .
[0020]
(28) is an SCR connected between the connection portion of the second heating resistor (22) and the fourth diode (27) and the electrode (B) of the AC power source (13), and the first diode (24) They are arranged in the same direction.
[0021]
(29) is a fifth diode in which the anode is connected to the connection part of the relay contact (18) and the heating area changeover switch (14), (30) is a resistor connected to the cathode of the fifth diode (29), (31 ) Is a sixth diode connected in series to the resistor (30), (32) is a capacitor connected to the sixth diode (31), and (33) is a connection between the sixth diode (31) and the capacitor (32). And a gate circuit connected to the gate of the SCR (28), and (34) is a power supply circuit of the relay (35) connected to the connection of the first heating resistor (21) and the third diode (26). It comprises a resistor (36) and a series circuit (38) of a DC conversion diode (37). (39) is a transistor connected in series to the power supply circuit (34), and its base is connected to the output terminal (P ₀ ) of the control circuit (19). (40) is a resistance.
[0022]
(41) is a seventh diode connected between the connection portion of the resistor (30) and the sixth diode (31) and the collector of the transistor (39). (42) is a power switch.
[0023]
Next, the operation will be described. When the contact (17) is connected to the contact (15), the heating area changeover switch (14) generates heat only in the first heating element (5), for example, the left half generates heat and is connected to the contact (16). In this case, only the second heating element (6) generates heat, for example, the right half generates heat, and when connected to both contacts (15) and (16), the respective heating elements (5) and (6 ) Generate heat and the entire surface is heated.
[0024]
Now, a case where the heating area changeover switch (14) is switched to set the first heating element (5) to generate heat will be described. When the power switch (42) is closed and energization is started, the temperature of the carpet body is initially lower than the set temperature set by the control circuit (19), so the output terminal (P0) of the control circuit (19) The output becomes “H”, the transistor (39) is turned on, the relay (35) is driven, and the relay contact (18) is turned on.
[0025]
That is, in the reverse half wave, the electrode (A) of the AC power source (13) -the first diode (24) -the second heating resistor (22) -the fourth diode (27) -for the first and second short circuits. A voltage across the third diode (26) is applied to the relay (35) through a path of the conductors (9), (10) and the first heating resistor (21).
[0026]
With the relay contact (18) turned on, the electrode (A) of the AC power supply (13) -the relay contact (18) -the heating area changeover switch (14) -the first heating wire (5) -the AC power supply (13) The first heating wire (5) generates heat in the path of the electrode (B) and the path in the opposite direction.
[0027]
Eventually, when the temperature of the carpet rises and reaches the set temperature, the output terminal (P0) of the control circuit (19) becomes “L”, so that the transistor (39) is turned off and the driving of the relay (35) is stopped. Then, the relay contact (18) is turned off, and the energization to the first heating wire (5) is stopped.
[0028]
After that, when the temperature of the carpet body decreases and falls to a temperature outside the allowable temperature range of the set temperature, the output terminal (P ₀ ) of the control circuit (19) becomes “H” and the relay contact (18) as described above. Is turned on and the first heating wire (5) is energized again to heat the carpet body.
[0029]
If the output of the output terminal (P ₀ ) of the control circuit (19) becomes “L”, the drive of the relay (35) is stopped, the relay contact (18) is turned off, and the first heating element (1) is turned off. When the relay contact (18) is welded due to aging or the like despite the operation to stop the heating wire (5), the transistor (39) is turned off as described above. The SCR (28) is triggered by the gate circuit (33) by the path of the relay contact (18) -the fifth diode (29) -the resistor (30) -the sixth diode (31), and the first diode (24) -The thermal fuse (20) is blown by the path of the second heating resistor (22) -SCR (28) to stop energization of the first heating wire (5).
[0030]
Thus, during the heat generation operation of the first heating wire (5), abnormal heating occurs for some reason, and the first heating wire (5) and the first short-circuiting conductor (9) at the point (a) shown in FIG. ) Is short-circuited, the electrode (B) of the AC power supply (13) -the thermal fuse (20) -the third diode (26) -the first heating resistor (21) -the first short-circuiting conductor (9) -the short-circuiting. The first heating resistor (21) generates heat in the path of the point (a) -heating area selector switch (14) -relay contact (18) -electrode (A) of the AC power source (13), and the thermal fuse (20) is blown. To do.
[0031]
(B) When short-circuited at the point, the electrode (A) of the AC power source (13) -the first diode (24) -the second heating resistor (22) -the fourth diode (27) -the first and second short-circuits. The second heating resistor (22) generates heat in the path of the conductors (9), (10) -the short-circuit point (b) -the electrode (B) of the AC power supply (13), thereby blowing the thermal fuse (20).
[0032]
Here, if an abnormality occurs at two points (a) and (b) at the same time and a short circuit occurs, the electrode ( B ) of the AC power source (13) -the thermal fuse (20) -the short-circuit point (b) -2nd diode (25)-2nd heating resistance (22)-4th diode (27)-2nd conductor for short circuit (10)-Short circuit point (a)-Heating area changeover switch (14) -Electrode ( A path hand second heating resistor) (22) to blow the thermal fuse by heating (20).
[0033]
In addition, when the heating area changeover switch (14) is switched and only the second heating element (6) is set to generate heat, the same operation as described above can be performed even during abnormal overheating. If short-circuit point, the first heating resistor (21) generates heat, blowing If short-circuit point (d), each temperature fuse second heating resistor (22) is heated (20). When the points (c) and (d) are short-circuited at the same time , the electrode (A) of the AC power source (13) -the first diode (24) -the second heating resistor (22) -the fourth diode (27)- The second heating resistor (22) generates heat in the path of the short circuit point (d) -temperature fuse (20) -electrode (B) of the AC power supply (13), and the temperature fuse (20) is blown.
[0034]
Thus, during the heat generation operation of the first or second heating element (1), (2) or at the start of the heat generation operation, a part of the first or second short-circuit conductor (9), (10) is used. In the case of disconnection, the first and second short-circuit conductors (9) and (10) are connected in series, so that no matter which short-circuit conductor is disconnected, the power supply circuit of the relay (35) ( 34) Even if no voltage is applied to the side and the output terminal (P ₀ ) of the control circuit (19) becomes “H”, the relay (35) is not driven and the heating wire (5) or (6) is reached. Is turned off.
[0035]
【The invention's effect】
As described above, the present invention ensures that the first and second heating resistances are obtained even when abnormal heating occurs at a plurality of locations of the heating wire and the shorting conductor and the heating wire and the shorting conductor are short-circuited at the plurality of locations. Each generates heat and the thermal fuse is blown to prevent continuous heating of the heating wire.
[0036]
In addition, by supplying power to the power control element through a series circuit of the shorting conductor and the heating resistor , when the shorting conductor is disconnected, the power necessary for opening and closing the power control element is not supplied, and The current is cut off and heat generation stops immediately.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an embodiment of a temperature control circuit of the present invention.
FIG. 2 is also an explanatory diagram of a heating element.
FIG. 3 is a plan view of a thermal fuse assembly.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 1st heat generating body 2 2nd heat generating body 5 1st heat generating line 6 2nd heat generating line 9 1st short circuit conductor 10 2nd short circuit conductor 13 AC power supply 18 Power control element (relay contact)
19 control circuit 20 thermal fuse 21 first heating resistor 22 second heating resistor 24 first diode 25 second diode 26 third diode 27 fourth diode

Claims

A heating element; a power control element connected in series to the heating element; a temperature fuse connected in series to the heating element; and detecting the temperature of the heating element to open and close the power control element to bring the heating element to a predetermined temperature. The heating element includes an exothermic wire, a short-circuit conductor, a thermal melt layer interposed between the short-circuit conductor and the exothermic wire and melted at a predetermined temperature or more, and an insulating layer covering an outer periphery of the short-circuit conductor. The thermal fuse provided to cut off the energization to the heating element is configured to flow current through the first and second heating resistors disposed in the vicinity thereof and to heat and melt by the generated heat. The first diode, the second diode in the opposite direction to the diode, the first heating resistor, and the third diode in the opposite direction to the first diode are connected in series between both ends of the first diode, and the second diode Heating resistance and the first diode Temperature control circuit, characterized in that the de the same direction of the fourth diode series circuit of the short-circuit conductor are connected in parallel.

A power supply necessary to open and close the power control element is supplied from a connection point of the first heating resistor and the third diode through a series circuit of the first diode, the second heating resistor, the fourth diode, and a short-circuiting conductor. The temperature control circuit according to claim 1.