JP2021004589A - Igniter for internal combustion engine - Google Patents

Igniter for internal combustion engine Download PDF

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JP2021004589A
JP2021004589A JP2019119629A JP2019119629A JP2021004589A JP 2021004589 A JP2021004589 A JP 2021004589A JP 2019119629 A JP2019119629 A JP 2019119629A JP 2019119629 A JP2019119629 A JP 2019119629A JP 2021004589 A JP2021004589 A JP 2021004589A
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semiconductor switch
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voltage
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primary coil
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JP7286442B2 (en
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直樹 樋口
Naoki Higuchi
直樹 樋口
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Hitachi Astemo Hanshin Ltd
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Hitachi Automotive Systems Hanshin Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract

To provide an igniter for an internal combustion engine in which a risk that further failure may occur is eliminated by forcibly stopping electrification to a primary coil with a fail-safe function.SOLUTION: In an igniter 1 for an internal combustion engine, a main semiconductor switch 30 is provided on the ground side of an ignition coil 10, and a sub-semiconductor switch 60 is provided on a power supply side of the ignition coil 10. Even if a fail-safe means 70 is activated by detecting an abnormality and the sub-semiconductor switch 60 is turned off, the ground side of the main semiconductor switch 30 does not float, so that it is possible to avoid a situation in which energy stored by electrification to a primary coil 11 damages an internal circuit.SELECTED DRAWING: Figure 1

Description

本発明は、内燃機関の点火プラグに火花放電を生じさせる高電圧を印加するための内燃機関用点火装置に関する。 The present invention relates to an internal combustion engine ignition device for applying a high voltage that causes a spark discharge to an internal combustion engine spark plug.

内燃機関用点火装置は、内燃機関の点火サイクルを統括的に管理する点火制御装置（例えば、ＥＣＵ）から点火信号を受けて、所要のタイミングで一次コイルへの通電および遮断を制御し、二次コイルに高電圧を発生させる。二次コイルに発生した高電圧により、点火プラグの放電ギャップ間に火花放電を生じさせ、気筒内の燃焼ガスに着火し、気筒内のシリンダを動かす力を得るのである。 The ignition device for an internal combustion engine receives an ignition signal from an ignition control device (for example, an ECU) that comprehensively manages the ignition cycle of the internal combustion engine, controls energization and cutoff of the primary coil at a required timing, and secondary Generates a high voltage in the coil. The high voltage generated in the secondary coil causes a spark discharge between the discharge gaps of the spark plug, ignites the combustion gas in the cylinder, and obtains the force to move the cylinder in the cylinder.

そして、内燃機関用点火装置では、一次コイルへの通電路をパワートランジスタやＩＧＢＴといった半導体スイッチによって開閉し、一次コイルへの通電・遮断を制御している。半導体スイッチは、その性質上、昇温によって動作が不安定になってしまうので、半導体スイッチが異常状態になってしまった場合、異常な点火動作を強制的に停止させるフェールセーフ機能を設けた発明が提案されている（例えば、特許文献１を参照）。 Then, in the ignition device for an internal combustion engine, the energization path to the primary coil is opened and closed by a semiconductor switch such as a power transistor or an IGBT to control energization / disconnection of the primary coil. Due to its nature, the operation of a semiconductor switch becomes unstable due to temperature rise. Therefore, an invention provided with a fail-safe function that forcibly stops an abnormal ignition operation when the semiconductor switch becomes abnormal. Has been proposed (see, for example, Patent Document 1).

特許文献１に記載されたフェールセーフ機能の概要を図４および図５に基づいて説明する。点火コイルの一次コイル１０１へ直流電源１０２から電源供給する給電路の適所に第１半導体スイッチ１０３を設け、更に、第１半導体スイッチ１０３の接地側（直流電源１０２の低圧側）に第２半導体スイッチ１０４を設ける。そして、制御回路部１０５からの制御信号入力で第１，第２半導体スイッチ１０３，１０４が同時に閉じると、一次コイル１０１への通電路が形成され、一次コイル１０１に一次電流が流れる。また、制御回路１０５は、一次コイル１０１の通電路適所（例えば、第２半導体スイッチ１０４の接地側）に設けたセンス抵抗１０６から一次電流値を検出する。 The outline of the fail-safe function described in Patent Document 1 will be described with reference to FIGS. 4 and 5. The first semiconductor switch 103 is provided at an appropriate position in the power supply path for supplying power from the DC power supply 102 to the primary coil 101 of the ignition coil, and the second semiconductor switch is further provided on the ground side (low voltage side of the DC power supply 102) of the first semiconductor switch 103. 104 is provided. Then, when the first and second semiconductor switches 103 and 104 are closed at the same time by the control signal input from the control circuit unit 105, an energizing path to the primary coil 101 is formed and the primary current flows through the primary coil 101. Further, the control circuit 105 detects the primary current value from the sense resistor 106 provided at an appropriate position in the current-carrying path of the primary coil 101 (for example, the ground side of the second semiconductor switch 104).

例えば、第１半導体スイッチ１０３の短絡または損傷によって一次電流値が異常になっているような場合、第２半導体スイッチ１０４をオフにすることで、一次コイル１０１への通電路を開いて異常な点火制御が行われないようにし、内燃機関用点火装置全体を保護する。 For example, when the primary current value becomes abnormal due to a short circuit or damage of the first semiconductor switch 103, turning off the second semiconductor switch 104 opens an energizing path to the primary coil 101 and causes abnormal ignition. Prevents control and protects the entire ignition system for internal combustion engines.

また、特許文献１には、第２半導体スイッチ１０４が故障していないかをチェックするためのリーク検出機能を制御回路部１０５に設ける構成も提案されている。制御回路部１０５は、リークチェック線路１０７を介して第１半導体スイッチ１０３と第２半導体スイッチ１０４との間にリークチェック出力を行うことで、リーク検出用のパルス電圧を第２半導体スイッチ１０４に印加する。 Further, Patent Document 1 also proposes a configuration in which the control circuit unit 105 is provided with a leak detection function for checking whether or not the second semiconductor switch 104 has failed. The control circuit unit 105 applies a pulse voltage for leak detection to the second semiconductor switch 104 by performing a leak check output between the first semiconductor switch 103 and the second semiconductor switch 104 via the leak check line 107. To do.

例えば、図５の波形図に示すように、一次コイル１０１への給電開始および終了のタイミングを決める点火信号Ｓｉが入力されたタイミングで短パルス状のリークチェックパルスをリークチェック線路１０７へ出力する。第２半導体スイッチ１０４が正常であれば、センス抵抗１０６に電流は流れないが、第２半導体スイッチ１０４が短絡あるいは損傷によって導通していれば、センス抵抗１０６に電流が流れるために、第２半導体スイッチ１０４の異常を検出できる。また、第１半導体スイッチ１０３が短絡または損傷によって導通していれば、第２半導体スイッチ１０４がオフのとき、リークチェック線路１０７には電源電圧が印加されるため、第１半導体スイッチ１０３の異常を検出できる。 For example, as shown in the waveform diagram of FIG. 5, a short pulse leak check pulse is output to the leak check line 107 at the timing when the ignition signal Si that determines the timing of the start and end of power supply to the primary coil 101 is input. If the second semiconductor switch 104 is normal, no current flows through the sense resistor 106, but if the second semiconductor switch 104 is conducting due to a short circuit or damage, a current flows through the sense resistor 106, so that the second semiconductor An abnormality of the switch 104 can be detected. Further, if the first semiconductor switch 103 is conducting due to a short circuit or damage, when the second semiconductor switch 104 is off, a power supply voltage is applied to the leak check line 107, so that an abnormality of the first semiconductor switch 103 occurs. Can be detected.

米国特許第９７４５９４７号明細書U.S. Pat. No. 9745947

しかしながら、特許文献１に記載されている内燃機関用点火装置では、第２半導体スイッチを第１半導体スイッチの接地側に設けているため、フェールセーフ機能が働いて第２半導体スイッチをオフにした場合、第１半導体スイッチの接地側が浮いた状態になる。このため、一次コイルへの通電により蓄えられた高エネルギーが第１半導体スイッチおよびリークチェック線路を介して制御回路部へ一気に流れ込み、制御回路部を破損してしまう危険性がある。 However, in the ignition device for an internal combustion engine described in Patent Document 1, since the second semiconductor switch is provided on the ground side of the first semiconductor switch, the fail-safe function is activated and the second semiconductor switch is turned off. , The ground side of the first semiconductor switch is in a floating state. Therefore, there is a risk that the high energy stored by energizing the primary coil will flow into the control circuit section at once via the first semiconductor switch and the leak check line, and the control circuit section will be damaged.

また、リークチェック出力パルスを生成して第１，第２半導体スイッチの異常をチェックする場合、そのチェックは高インピーダンス状態で行う必要がある。そのため、サージ・ノイズの影響を受けやすく、誤判定が生じやすいという問題が生じる。さらに、異常検知用のリークチェック出力パルスの生成は、点火信号ＳｉのＯＮ（信号レベルがＬからＨ）をトリガーとしているため、リークチェックのタイミングが制限されてしまう。点火信号ＳｉがＯＦＦのときにも、リークチェックを任意で行えることが望ましい。 Further, when a leak check output pulse is generated to check an abnormality of the first and second semiconductor switches, the check must be performed in a high impedance state. Therefore, there arises a problem that it is easily affected by surge noise and erroneous determination is likely to occur. Further, since the generation of the leak check output pulse for abnormality detection is triggered by the ON of the ignition signal Si (the signal level is from L to H), the timing of the leak check is limited. It is desirable that the leak check can be performed arbitrarily even when the ignition signal Si is OFF.

そこで、本発明は、フェールセーフ機能によって一次コイルへの通電を強制的に停止することで、更なる故障が生じる危険性の無い内燃機関用点火装置の提供を目的とする。 Therefore, an object of the present invention is to provide an ignition device for an internal combustion engine without a risk of further failure by forcibly stopping the energization of the primary coil by a fail-safe function.

上記課題を解決するための内燃機関用点火装置は、点火サイクルの所要タイミングで入力される点火信号に基づいて、点火コイルの一次コイルに流れる一次電流を通電・遮断制御し、二次側に高電圧を発生させる内燃機関用点火装置において、前記一次コイルと接地点との間に設けられ、前記点火信号のオン・オフに応じて一次コイルから接地点への通電路を開閉する主半導体スイッチと、前記一次コイルと電源との間に設けられ、該電源から前記一次コイルへの通電路を開閉する副半導体スイッチと、前記主半導体スイッチの異常状態を検出することに基づいて、前記副半導体スイッチのオン動作を規制するフェールセーフ手段と、を備えることを特徴とする。 The ignition device for an internal combustion engine for solving the above problems controls the energization and cutoff of the primary current flowing through the primary coil of the ignition coil based on the ignition signal input at the required timing of the ignition cycle, and raises the value to the secondary side. In an ignition device for an internal combustion engine that generates a voltage, a main semiconductor switch provided between the primary coil and the grounding point that opens and closes a current path from the primary coil to the grounding point according to the on / off of the ignition signal. , The sub-semiconductor switch provided between the primary coil and the power supply to open and close the current path from the power supply to the primary coil, and the sub-semiconductor switch based on detecting an abnormal state of the main semiconductor switch. It is characterized by providing a fail-safe means for regulating the on-operation of the.

また、上記構成において、前記フェールセーフ手段は、前記主半導体スイッチが異常状態から正常状態へ復帰したことを検出することに基づいて、前記副半導体スイッチのオン動作規制を解除しても良い。 Further, in the above configuration, the fail-safe means may release the on-operation restriction of the sub-semiconductor switch based on detecting that the main semiconductor switch has returned from the abnormal state to the normal state.

また、上記構成において、前記副半導体スイッチとして、Ｐ型ＭＯＳＦＥＴを用い、前記フェールセーフ手段は、前記主半導体スイッチが正常状態のとき、前記点火信号と同期して前記副半導体スイッチのゲート−ソース間電圧を低減させて、電源から前記一次コイルへの通電路を閉じ、前記主半導体スイッチが異常状態のとき、前記副半導体スイッチのゲート−ソース間電圧を通常電圧に保持しても良い。 Further, in the above configuration, a P-type MOSFET is used as the sub-semiconductor switch, and the fail-safe means is used between the gate and the source of the sub-semiconductor switch in synchronization with the ignition signal when the main semiconductor switch is in a normal state. The voltage may be reduced to close the energizing path from the power source to the primary coil, and when the main semiconductor switch is in an abnormal state, the gate-source voltage of the sub-semiconductor switch may be maintained at a normal voltage.

また、上記構成において、前記フェールセーフ手段は、前記副半導体スイッチのドレイン−ソース間を接続する異常検出用抵抗と、前記副半導体スイッチと前記一次コイルとの間に設けた異常検出点の電圧を取得する判定電圧取得線と、前記判定電圧取得線から取得した異常判定電圧と、正常判定閾値である基準電圧とを比較して、正常判定の場合にのみ正常信号を出力する比較器と、前記副半導体スイッチのゲートから前記接地点に至る通電路に設けられ、前記比較器からの正常信号が入力されることで、前記副半導体スイッチのゲートから前記接地点に至る通電路を閉じる正常動作用半導体スイッチと、を備えても良い。 Further, in the above configuration, the fail-safe means applies an abnormality detection resistor for connecting the drain and the source of the sub-semiconductor switch and a voltage at an abnormality detection point provided between the sub-semiconductor switch and the primary coil. A comparator that compares the determination voltage acquisition line to be acquired, the abnormality determination voltage acquired from the determination voltage acquisition line, and the reference voltage which is the normal determination threshold, and outputs a normal signal only in the case of normal determination, and the above. For normal operation, which is provided in the energizing path from the gate of the sub-semiconductor switch to the grounding point and closes the energizing path from the gate of the sub-semiconductor switch to the grounding point by inputting a normal signal from the comparator. A semiconductor switch may be provided.

また、上記構成において、前記副半導体スイッチとして、ＰＮＰ型で高耐圧のＰＮＰパワートランジスタを用い、前記フェールセーフ手段は、前記主半導体スイッチが正常状態のとき、前記点火信号と同期して前記副半導体スイッチのベース−エミッタ間電圧を低減させて、電源から前記一次コイルへの通電路を閉じ、前記主半導体スイッチが異常状態のとき、前記副半導体スイッチのベース−エミッタ間電圧を通常電圧に保持しても良い。 Further, in the above configuration, a PNP type high withstand voltage PNP power transistor is used as the sub-semiconductor switch, and the fail-safe means means the sub-semiconductor in synchronization with the ignition signal when the main semiconductor switch is in a normal state. The base-emitter voltage of the switch is reduced, the energization path from the power supply to the primary coil is closed, and when the main semiconductor switch is in an abnormal state, the base-emitter voltage of the sub-semiconductor switch is maintained at the normal voltage. You may.

また、上記構成において、前記フェールセーフ手段は、前記副半導体スイッチのコレクタ−エミッタ間を接続する異常検出用抵抗と、前記副半導体スイッチと前記一次コイルとの間に設けた異常検出点の電圧を取得する判定電圧取得線と、前記判定電圧取得線から取得した異常判定電圧と、正常判定閾値である基準電圧とを比較して、正常判定の場合にのみ正常信号を出力する比較器と、前記副半導体スイッチのベースから前記接地点に至る通電路に設けられ、前記比較器からの正常信号が入力されることで、前記副半導体スイッチのベースから前記接地点に至る通電路を閉じる正常動作用半導体スイッチと、を備えても良い。 Further, in the above configuration, the fail-safe means applies an abnormality detection resistor that connects the collector and the emitter of the sub-semiconductor switch and a voltage at an abnormality detection point provided between the sub-semiconductor switch and the primary coil. A comparator that compares the acquisition judgment voltage acquisition line, the abnormality judgment voltage acquired from the judgment voltage acquisition line, and the reference voltage which is the normal judgment threshold, and outputs a normal signal only in the case of normal judgment, and the above. For normal operation, which is provided in the energizing path from the base of the sub-semiconductor switch to the grounding point and closes the energizing path from the base of the sub-semiconductor switch to the grounding point by inputting a normal signal from the comparator. A semiconductor switch may be provided.

本発明に係る内燃機関用点火装置によれば、主半導体スイッチが異常状態になった場合、フェールセーフ手段によって、点火コイルと電源との間に設けた副半導体スイッチのオン動作を規制するので、主半導体スイッチの接地側が浮くことがない。よって、一次コイルへの通電により蓄えられたエネルギーは主半導体スイッチから接地点へ流れ、内燃機関用点火装置の更なる故障が生じる危険性はない。 According to the ignition device for an internal combustion engine according to the present invention, when the main semiconductor switch becomes abnormal, the fail-safe means regulates the on operation of the sub-semiconductor switch provided between the ignition coil and the power supply. The ground side of the main semiconductor switch does not float. Therefore, the energy stored by energizing the primary coil flows from the main semiconductor switch to the grounding point, and there is no risk of further failure of the ignition device for the internal combustion engine.

内燃機関用点火装置の本実施形態を示す概略回路図である。It is a schematic circuit diagram which shows this embodiment of the ignition device for an internal combustion engine. 正常時の内燃機関用点火装置における要部の信号波形を示す波形図である。It is a waveform diagram which shows the signal waveform of the main part in the ignition device for an internal combustion engine in a normal state. 異常時の内燃機関用点火装置における要部の信号波形を示す波形図である。It is a waveform diagram which shows the signal waveform of the main part in the ignition device for an internal combustion engine at the time of abnormality. フェールセーフ機能を備えた従来の内燃機関用点火装置の概略回路図である。It is a schematic circuit diagram of the conventional ignition device for an internal combustion engine provided with a fail-safe function. 従来の内燃機関用点火装置における要部の信号波形を示す波形図である。It is a waveform diagram which shows the signal waveform of the main part in the conventional ignition device for an internal combustion engine.

次に、本発明に係る内燃機関用点火装置１の実施形態を、添付図面に基づいて詳細に説明する。 Next, an embodiment of the ignition device 1 for an internal combustion engine according to the present invention will be described in detail with reference to the accompanying drawings.

内燃機関用点火装置１は、点火サイクルの所要タイミングで入力される点火信号Ｓｉに基づいて、点火コイル１０の一次コイル１１に流れる一次電流を通電・遮断制御し、点火コイル１０の二次コイル１２に高電圧を発生させる。二次コイル１２の一方には、図示を省略した点火プラグが接続され、二次コイル１２に発生した高電圧により、点火プラグの放電ギャップ間に火花放電を生じさせる。また、一次コイル１１には、直流電源２０から電源供給を受ける給電路が形成される。 The ignition device 1 for an internal combustion engine controls the energization and cutoff of the primary current flowing through the primary coil 11 of the ignition coil 10 based on the ignition signal Si input at the required timing of the ignition cycle, and controls the energization and cutoff of the secondary coil 12 of the ignition coil 10. To generate a high voltage. An ignition plug (not shown) is connected to one of the secondary coils 12, and a high voltage generated in the secondary coil 12 causes spark discharge between the discharge gaps of the spark plugs. Further, the primary coil 11 is formed with a power supply path for receiving power supply from the DC power supply 20.

点火コイル１０における一次コイル１１の低圧側と接地点ＧＮＤとの間には、点火信号Ｓｉのオン・オフに応じて一次コイル１１から接地点ＧＮＤへの通電路を開閉する主半導体スイッチ３０を設ける。なお、点火信号Ｓｉは、点火制御装置としてのＥＣＵ４０から点火サイクル中の適宜なタイミングで入力（例えば、信号レベルがＬからＨに変換）するもので、例えば、イグナイタ制御回路５０によって適宜な駆動信号に変換されて主半導体スイッチ３０へ入力される。 A main semiconductor switch 30 is provided between the low voltage side of the primary coil 11 of the ignition coil 10 and the grounding point GND to open and close the energizing path from the primary coil 11 to the grounding point GND according to the on / off of the ignition signal Si. .. The ignition signal Si is input from the ECU 40 as an ignition control device at an appropriate timing during the ignition cycle (for example, the signal level is converted from L to H). For example, an appropriate drive signal is provided by the igniter control circuit 50. Is converted to and input to the main semiconductor switch 30.

主半導体スイッチ３０として、例えば、ＩＧＢＴ（Insulated Gate Bipolar Transistor:絶縁ゲートバイポーラトランジスタ）を用いる。この場合、ＩＧＢＴのコレクタ端子を一次コイル１１と接続し、ＩＧＢＴのエミッタ端子を接地点ＧＮＤと接続し、ＩＧＢＴのゲート端子からイグナイタ制御回路５０の駆動信号を入力させれば、イグナイタ制御回路５０によって主半導体スイッチ３０をオン・オフできる。 As the main semiconductor switch 30, for example, an IGBT (Insulated Gate Bipolar Transistor) is used. In this case, if the collector terminal of the IGBT is connected to the primary coil 11, the emitter terminal of the IGBT is connected to the grounding point GND, and the drive signal of the igniter control circuit 50 is input from the gate terminal of the IGBT, the igniter control circuit 50 The main semiconductor switch 30 can be turned on / off.

また、一次コイル１１と直流電源２０との間には副半導体スイッチ６０を設け、直流電源２０から一次コイル１１へ至る通電路の開閉を行う。副半導体スイッチ６０として、例えば、Ｐ型ＭＯＳＦＥＴ（Metal-Oxide-Semiconductor Field-Effect Transistor）を用いる。この場合、Ｐ型ＭＯＳＦＥＴのソース端子を直流電源２０と接続し、Ｐ型ＭＯＳＦＥＴのドレイン端子を一次コイル１１と接続し、ゲート端子からフェールセーフ手段７０のコントロール信号を入力させれば、フェールセーフ手段７０によって副半導体スイッチ６０をオン・オフできる。 Further, an auxiliary semiconductor switch 60 is provided between the primary coil 11 and the DC power supply 20 to open and close the energizing path from the DC power supply 20 to the primary coil 11. As the sub-semiconductor switch 60, for example, a P-type MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is used. In this case, if the source terminal of the P-type MOSFET is connected to the DC power supply 20, the drain terminal of the P-type MOSFET is connected to the primary coil 11, and the control signal of the fail-safe means 70 is input from the gate terminal, the fail-safe means The sub-semiconductor switch 60 can be turned on / off by the 70.

フェールセーフ手段７０は、主半導体スイッチ３０の異常状態を検出することに基づいて、副半導体スイッチ６０のオン動作を規制することで、一次コイル１１から主半導体スイッチ３０へ一次電流が流れることを防ぐ。主半導体スイッチ３０の異常が素子の発熱に起因するものであった場合、一次コイル１１への通電を無効化することで主半導体スイッチ３０の温度低下を促し、主半導体スイッチ３０を正常動作可能な状態（正常状態）へ復帰させる。フェールセーフ手段７０は、主半導体スイッチ３０が異常状態から正常状態へ復帰したことを検出すると、副半導体スイッチ６０のオン動作規制を解除する。すなわち、フェールセーフ手段７０は、主半導体スイッチ３０の異常状態検出で一次コイル１１への通電を遮断すると共に、主半導体スイッチ３０の正常状態復帰へ一次コイル１１への通電を再開させることができる。 The fail-safe means 70 regulates the on operation of the sub-semiconductor switch 60 based on detecting an abnormal state of the main semiconductor switch 30, thereby preventing the primary current from flowing from the primary coil 11 to the main semiconductor switch 30. .. When the abnormality of the main semiconductor switch 30 is caused by the heat generation of the element, the temperature of the main semiconductor switch 30 can be lowered by disabling the energization of the primary coil 11, and the main semiconductor switch 30 can be operated normally. Return to the state (normal state). When the fail-safe means 70 detects that the main semiconductor switch 30 has returned from the abnormal state to the normal state, the fail-safe means 70 releases the on-operation restriction of the sub-semiconductor switch 60. That is, the fail-safe means 70 can cut off the energization of the primary coil 11 by detecting the abnormal state of the main semiconductor switch 30, and restart the energization of the primary coil 11 to return the main semiconductor switch 30 to the normal state.

フェールセーフ手段７０の機能は、耐熱性・耐ノイズ性の高いディスクリート部品を適宜に用いた種々の回路を適宜に組み合わせることで構成できる。しかしながら、図１に示すフェールセーフ手段７０の回路構成であれば、サージ・ノイズの影響を受け難いシンプルな異常検出構造で、しかも、点火信号Ｓｉのオン・オフにかかわらず、常に主半導体スイッチ３０の異常を監視できる。 The function of the fail-safe means 70 can be configured by appropriately combining various circuits that appropriately use discrete components having high heat resistance and noise resistance. However, the circuit configuration of the fail-safe means 70 shown in FIG. 1 has a simple abnormality detection structure that is not easily affected by surge noise, and the main semiconductor switch 30 is always on and off regardless of whether the ignition signal Si is on or off. Abnormality can be monitored.

フェールセーフ手段７０は、適宜な抵抗成分を含む動作用給電線Ｌ１を介して、直流電源２０から電源供給を受ける。なお、動作用給電線Ｌ１に乗ってフェールセーフ手段７０へ混入したサージ・ノイズから内部素子を保護するために、ショットキーバリアダイオードＳＤを用いた保護回路を設けてある。動作用給電線Ｌ１は、副スイッチ用給電線Ｌ２と比較器用給電線Ｌ３に分岐させる。副スイッチ用給電線Ｌ２の電圧は、副半導体スイッチ６０のソース電圧とほぼ同じ（副半導体スイッチゲート電圧Ｖｇ＝Ｈレベル）であるから、副半導体スイッチ６０はオフのままである。一方、比較器用給電線Ｌ３は、比較器７１の正電源端子＋に接続され、非反転入力Ｖｉｎ＋が反転入力Ｖｉｎ−よりも高いときの出力Ｖｏｕｔの生成に用いられる。なお、比較器７１の負電源端子−は接地点ＧＮＤに接続され、反転入力Ｖｉｎ−が非反転入力Ｖｉｎ＋よりも高いときの出力Ｖｏｕｔは接地電圧となる。 The fail-safe means 70 receives power from the DC power source 20 via an operation feeder line L1 containing an appropriate resistance component. A protection circuit using a Schottky barrier diode SD is provided in order to protect the internal element from surge noise mixed in the fail-safe means 70 on the operation feeder line L1. The operation feed line L1 is branched into a sub switch feeder line L2 and a comparator feed line L3. Since the voltage of the feeder line L2 for the sub-switch is substantially the same as the source voltage of the sub-semiconductor switch 60 (sub-semiconductor switch gate voltage Vg = H level), the sub-semiconductor switch 60 remains off. On the other hand, the feeder line L3 for the comparator is connected to the positive power supply terminal + of the comparator 71, and is used to generate an output Vout when the non-inverting input Vin + is higher than the inverting input Vin−. The negative power supply terminal − of the comparator 71 is connected to the grounding point GND, and the output Vout when the inverting input Vin− is higher than the non-inverting input Vin + becomes the grounding voltage.

副半導体スイッチ６０のゲート入力となる副スイッチ用給電線Ｌ２は、副スイッチ動作制御線Ｌ４を介して、正常動作用半導体スイッチ７２（例えば、バイポーラトランジスタで構成）のコレクタ端子に接続する。正常動作用半導体スイッチ７２のエミッタ端子は接地点ＧＮＤに接続され、正常動作用半導体スイッチ７２のベース端子には、比較器７１の出力Ｖｏｕｔが入力される。比較器７１の出力Ｖｏｕｔが正常動作用半導体スイッチ７２のベースに入力されると、副スイッチ動作制御線Ｌ４が接地点ＧＮＤに接続されて副スイッチ素子６０のゲート電圧が下がり（副半導体スイッチゲート電圧Ｖｇ＝Ｌレベル）、副半導体スイッチ６０がオンとなる。すなわち、主半導体スイッチ３０が正常状態か異常状態かの判定を比較器７１で行い、正常状態の比較結果である出力Ｖｏｕｔを正常動作用半導体スイッチ７２のベースに入力してオンにすれば、連携して副半導体スイッチ６０をオフからオンに制御できる。 The feed line L2 for the sub switch, which is the gate input of the sub semiconductor switch 60, is connected to the collector terminal of the semiconductor switch 72 for normal operation (for example, composed of a bipolar transistor) via the sub switch operation control line L4. The emitter terminal of the semiconductor switch 72 for normal operation is connected to the grounding point GND, and the output Vout of the comparator 71 is input to the base terminal of the semiconductor switch 72 for normal operation. When the output Vout of the comparator 71 is input to the base of the semiconductor switch 72 for normal operation, the sub switch operation control line L4 is connected to the grounding point GND and the gate voltage of the sub switch element 60 drops (sub semiconductor switch gate voltage). Vg = L level), the sub-semiconductor switch 60 is turned on. That is, if the comparator 71 determines whether the main semiconductor switch 30 is in the normal state or the abnormal state, and the output Vout, which is the comparison result of the normal state, is input to the base of the semiconductor switch 72 for normal operation and turned on, the cooperation is established. The sub-semiconductor switch 60 can be controlled from off to on.

上記のように比較器７１で主半導体スイッチ３０の正常状態と異常状態を判定するための構成を以下に説明する。 As described above, the configuration for determining the normal state and the abnormal state of the main semiconductor switch 30 by the comparator 71 will be described below.

副半導体スイッチ６０のドレイン−ソース間を接続するバイパス線路Ｌ５に高抵抗の異常検出用抵抗７３を設ける。また、副半導体スイッチ６０と一次コイル１１との間に設けた異常検出点７４の異常判定電圧を取得する判定電圧取得線Ｌ６を設け、判定電圧取得線Ｌ６を比較器７１の非反転入力Ｖｉｎ＋に接続する。なお、比較器７１の非反転入力Ｖｉｎ＋が適宜な入力電圧となるように、判定電圧取得線Ｌ６中の抵抗成分や接地点ＧＮＤに接続した接地接続線中の抵抗成分を適宜に定める。また、判定電圧取得線Ｌ６に乗って混入したサージ・ノイズから比較器７１を保護するために、ツェナーダイオードＺＤを用いた保護回路を設けてある。 A high-resistance abnormality detection resistor 73 is provided on the bypass line L5 connecting the drain and source of the sub-semiconductor switch 60. Further, a determination voltage acquisition line L6 for acquiring the abnormality determination voltage of the abnormality detection point 74 provided between the sub-semiconductor switch 60 and the primary coil 11 is provided, and the determination voltage acquisition line L6 is used as the non-inverting input Vin + of the comparator 71. Connecting. The resistance component in the determination voltage acquisition line L6 and the resistance component in the ground connection line connected to the ground point GND are appropriately determined so that the non-inverting input Vin + of the comparator 71 has an appropriate input voltage. Further, in order to protect the comparator 71 from surge noise mixed on the determination voltage acquisition line L6, a protection circuit using a Zener diode ZD is provided.

一方、比較器７１の反転入力Ｖｉｎ−には、非反転入力Ｖｉｎ＋の異常判定電圧を正常判定もしくは異常判定に切り分ける閾値（正常判定閾値）とする基準電圧を入力する。この基準電圧は、定電流源等から直接生成しても良いが、本実施形態では、基準電圧生成手段８０によって生成する。基準電圧生成手段８０では、比較器用給電線Ｌ３と比較器７１の反転入力線Ｌ７を接続する第１分圧線Ｌ８ａに設けた第１抵抗８１ａと、第１分圧線Ｌ８ａから接地点ＧＮＤを繋ぐ第２分圧線Ｌ８ｂに設けた第２抵抗８１ｂとで、比較器用給電線Ｌ３の電位を分圧し、基準電圧とする。 On the other hand, a reference voltage is input to the inverting input Vin− of the comparator 71 as a threshold value (normal determination threshold value) for dividing the abnormality determination voltage of the non-inverting input Vin + into normal determination or abnormality determination. This reference voltage may be generated directly from a constant current source or the like, but in the present embodiment, it is generated by the reference voltage generating means 80. In the reference voltage generating means 80, the first resistor 81a provided on the first voltage dividing line L8a connecting the power supply line L3 for the comparator and the inverting input line L7 of the comparator 71, and the grounding point GND from the first voltage dividing line L8a are provided. The potential of the power supply line L3 for the comparator is divided by the second resistor 81b provided on the second voltage dividing line L8b to be connected, and used as the reference voltage.

また、第２分圧線Ｌ８ｂの適所（例えば、第２抵抗８１ｂよりも接地点ＧＮＤ側）には、基準電圧生成用半導体スイッチ８２（例えば、バイポーラトランジスタで構成）を設けてある。基準電圧生成用半導体スイッチ８２は、コレクタ端子を高圧側、エミッタ端子を接地側に接続し、ＥＣＵ４０からの点火信号Ｓｉを適宜な電圧にしてゲート端子に入力する。よって、点火信号ＳｉがＥＣＵ４０から出力されていないとき、基準電圧生成用半導体スイッチ８２はオフであるから、比較器７１の反転入力線Ｌ７には、比較器用給電線Ｌ３とほぼ同じ電圧（Ｈレベル）が印加される。一方、点火信号ＳｉがＥＣＵ４０から出力されると、基準電圧生成用半導体スイッチ８２がオンとなって第２分圧線Ｌ８ｂが接地点ＧＮＤに接続され、比較器７１の反転入力線Ｌ７には、第１，第２抵抗８１ａ，８１ｂの分圧比に応じた電圧（Ｌレベル）が印加される。すなわち、比較器７１の反転入力Ｖｉｎ−には、点火信号Ｓｉのオン・オフに応じて、異なる基準電圧信号が入力されることとなる。 Further, a reference voltage generation semiconductor switch 82 (for example, composed of a bipolar transistor) is provided at an appropriate position of the second voltage dividing line L8b (for example, the grounding point GND side of the second resistor 81b). In the reference voltage generation semiconductor switch 82, the collector terminal is connected to the high voltage side and the emitter terminal is connected to the ground side, and the ignition signal Si from the ECU 40 is set to an appropriate voltage and input to the gate terminal. Therefore, when the ignition signal Si is not output from the ECU 40, the reference voltage generation semiconductor switch 82 is off, so that the inverting input line L7 of the comparator 71 has substantially the same voltage (H level) as the feeder line L3 for the comparator. ) Is applied. On the other hand, when the ignition signal Si is output from the ECU 40, the reference voltage generation semiconductor switch 82 is turned on, the second voltage dividing line L8b is connected to the grounding point GND, and the inverting input line L7 of the comparator 71 is connected to. A voltage (L level) corresponding to the voltage dividing ratio of the first and second resistors 81a and 81b is applied. That is, different reference voltage signals are input to the inverting input Vin− of the comparator 71 according to the on / off of the ignition signal Si.

ここで、上記のように構成した内燃機関用点火装置１における正常時の動作を、図２の波形図を用いて説明する。 Here, the normal operation of the internal combustion engine ignition device 1 configured as described above will be described with reference to the waveform diagram of FIG.

内燃機関用点火装置１が正常な状態において、点火信号Ｓｉが入力されていないとき（信号レベルがＬのとき）、主半導体スイッチ３０および副半導体スイッチ６０は共にオフである。よって、異常検出点７４には、異常検出用抵抗７３を設けたバイパス線路Ｌ５を介して電源電圧に近い高電圧が印加され、判定電圧取得線Ｌ６を介して比較器７１の非反転入力Ｖｉｎ＋には、高電位の異常判定電圧が入力される。このとき、基準電圧生成用半導体スイッチ８２はオフであるから、比較器７１の反転入力Ｖｉｎ−には、比較器用給電線Ｌ３とほぼ同じ電圧（Ｈレベル）が印加される。すなわち、「Ｖｉｎ−＞Ｖｉｎ＋」であるから、比較器７１の出力ＶｏｕｔはＬレベルのままで、正常動作用半導体スイッチ７２はオフを保持し、副スイッチ素子６０のゲート電圧ＶｇはＨレベルであるから、副半導体スイッチ６０もオフを保持する。 When the ignition device 1 for the internal combustion engine is in a normal state and the ignition signal Si is not input (when the signal level is L), both the main semiconductor switch 30 and the sub-semiconductor switch 60 are off. Therefore, a high voltage close to the power supply voltage is applied to the abnormality detection point 74 via the bypass line L5 provided with the abnormality detection resistor 73, and is applied to the non-inverting input Vin + of the comparator 71 via the determination voltage acquisition line L6. Is input with a high potential abnormality determination voltage. At this time, since the reference voltage generation semiconductor switch 82 is off, substantially the same voltage (H level) as that of the comparator feeding line L3 is applied to the inverting input Vin− of the comparator 71. That is, since "Vin-> Vin +", the output Vout of the comparator 71 remains at the L level, the semiconductor switch 72 for normal operation keeps off, and the gate voltage Vg of the sub switch element 60 is at the H level. Therefore, the sub-semiconductor switch 60 also keeps off.

次いで、内燃機関用点火装置１が正常な状態において、点火信号Ｓｉが入力されると（信号レベルがＨに変わると）、主半導体スイッチ３０がオンになり、一次コイル１１から接地点ＧＮＤに至る通電路が閉じる。同時に、基準電圧生成用半導体スイッチ８２がオンとなって第２分圧線Ｌ８ｂが接地点ＧＮＤに接続され、比較器７１の反転入力線Ｌ７には、第１，第２抵抗８１ａ，８１ｂの分圧比に応じた電圧（Ｌレベル）が印加される。すなわち、「Ｖｉｎ−＜Ｖｉｎ＋」に変化するから、比較器７１の出力ＶｏｕｔはＨレベルとなって正常動作用半導体スイッチ７２をオンにし、副スイッチ素子６０のゲート電圧ＶｇをＬレベルに低下させるから、副半導体スイッチ６０がオンになり、一次コイル１１への正常な通電路が形成され、一次電流Ｉ１が流れる。なお、副半導体スイッチ６０がオンになった後も、異常検出点７４には電源電圧に近い高電圧が印加されるので、比較器７１の非反転入力Ｖｉｎ＋に入力される異常判定電圧は高電位を保持する。よって、「Ｖｉｎ−＜Ｖｉｎ＋」の関係が保持され、比較器７１の出力ＶｏｕｔもＨレベルを保持する。 Next, when the ignition signal Si is input (when the signal level changes to H) in the normal state of the ignition device 1 for the internal combustion engine, the main semiconductor switch 30 is turned on, and the primary coil 11 reaches the grounding point GND. The energizing path closes. At the same time, the reference voltage generation semiconductor switch 82 is turned on, the second voltage dividing line L8b is connected to the grounding point GND, and the inverting input line L7 of the comparator 71 is connected to the first and second resistors 81a and 81b. A voltage (L level) corresponding to the pressure ratio is applied. That is, since it changes to "Vin- <Vin +", the output Vout of the comparator 71 becomes H level, the semiconductor switch 72 for normal operation is turned on, and the gate voltage Vg of the sub switch element 60 is lowered to L level. , The sub-semiconductor switch 60 is turned on, a normal energization path to the primary coil 11 is formed, and the primary current I1 flows. Even after the sub-semiconductor switch 60 is turned on, a high voltage close to the power supply voltage is applied to the abnormality detection point 74, so that the abnormality determination voltage input to the non-inverting input Vin + of the comparator 71 is a high potential. To hold. Therefore, the relationship of "Vin- <Vin +" is maintained, and the output Vout of the comparator 71 also maintains the H level.

さらに、内燃機関用点火装置１が正常な状態において、点火信号Ｓｉが停止すると（信号レベルがＬに戻ると）、主半導体スイッチ３０がオフになり、一次コイル１１から接地点ＧＮＤに至る通電路が開き、一次電流Ｉ１が遮断される。同時に、基準電圧生成用半導体スイッチ８２がオフとなって、比較器７１の反転入力線Ｌ７には、比較器用給電線Ｌ３とほぼ同じ電圧（Ｈレベル）が印加される。すなわち、「Ｖｉｎ−＞Ｖｉｎ＋」に変化するから、比較器７１の出力ＶｏｕｔはＬレベルとなって正常動作用半導体スイッチ７２をオフにし、副スイッチ素子６０のゲート電圧ＶｇをＨレベルに上昇させるから、副半導体スイッチ６０がオフになる。なお、副半導体スイッチ６０がオフになった後、異常検出点７４には、異常検出用抵抗７３を設けたバイパス線路Ｌ５を介して電源電圧に近い高電圧が印加されるので、比較器７１の非反転入力Ｖｉｎ＋に入力される異常判定電圧は高電位を保持する。よって、「Ｖｉｎ−＜Ｖｉｎ＋」の関係が保持され、比較器７１の出力ＶｏｕｔもＨレベルを保持する。 Further, when the ignition signal Si is stopped (when the signal level returns to L) in the normal state of the ignition device 1 for the internal combustion engine, the main semiconductor switch 30 is turned off and the current path from the primary coil 11 to the grounding point GND. Opens and the primary current I1 is cut off. At the same time, the reference voltage generation semiconductor switch 82 is turned off, and a voltage (H level) substantially the same as that of the comparator feeding line L3 is applied to the inverting input line L7 of the comparator 71. That is, since it changes to "Vin-> Vin +", the output Vout of the comparator 71 becomes L level, the semiconductor switch 72 for normal operation is turned off, and the gate voltage Vg of the sub switch element 60 is raised to H level. , The sub-semiconductor switch 60 is turned off. After the sub-semiconductor switch 60 is turned off, a high voltage close to the power supply voltage is applied to the abnormality detection point 74 via the bypass line L5 provided with the abnormality detection resistor 73, so that the comparator 71 The abnormality determination voltage input to the non-inverting input Vin + maintains a high potential. Therefore, the relationship of "Vin- <Vin +" is maintained, and the output Vout of the comparator 71 also maintains the H level.

次に、上記のように構成した内燃機関用点火装置１における異常時の動作を、図３の波形図を用いて説明する。 Next, the operation at the time of abnormality in the ignition device 1 for an internal combustion engine configured as described above will be described with reference to the waveform diagram of FIG.

内燃機関用点火装置１が異常な状態、例えば、主半導体スイッチ３０が昇温により短絡した状態において、点火信号Ｓｉが入力されていないとき（信号レベルがＬのとき）、副半導体スイッチ６０はオフである。しかしながら、短絡異常の主半導体スイッチ３０によって、一次コイル１１から接地点ＧＮＤへの通電路が閉じた状態となる。このため、一次コイル１１には、異常検出用抵抗７３を設けたバイパス線路Ｌ５を介して一次電流Ｉ１が流れ続けることとなる。ただし、高抵抗の異常検出用抵抗７３を設けてあるため、一次コイル１１への給電量はわずかとなり、飽和に達した微少な一次電流Ｉ１が流れるにとどめ、一次コイル１１による発熱および電力損失を抑制する。また、異常検出点７４には、電源電圧が異常検出用抵抗７３により電圧低下した低い電圧が印加され、判定電圧取得線Ｌ６を介して比較器７１の非反転入力Ｖｉｎ＋には、低電位の異常判定電圧が入力される。このとき、基準電圧生成用半導体スイッチ８２はオフであるから、比較器７１の反転入力Ｖｉｎ−には、比較器用給電線Ｌ３とほぼ同じ電圧（Ｈレベル）が印加される。すなわち、「Ｖｉｎ−＞Ｖｉｎ＋」であるから、比較器７１の出力ＶｏｕｔはＬレベルのままで、正常動作用半導体スイッチ７２はオフを保持し、副スイッチ素子６０のゲート電圧ＶｇはＨレベルであるから、副半導体スイッチ６０もオフを保持する。 When the ignition signal Si for the internal combustion engine is abnormal, for example, when the main semiconductor switch 30 is short-circuited due to temperature rise and the ignition signal Si is not input (when the signal level is L), the sub-semiconductor switch 60 is turned off. Is. However, the main semiconductor switch 30 with a short-circuit abnormality closes the energizing path from the primary coil 11 to the grounding point GND. Therefore, the primary current I1 continues to flow in the primary coil 11 via the bypass line L5 provided with the abnormality detection resistor 73. However, since the high resistance abnormality detection resistor 73 is provided, the amount of power supplied to the primary coil 11 is small, and only a minute primary current I1 that has reached saturation flows, and heat generation and power loss due to the primary coil 11 are eliminated. Suppress. Further, a low voltage whose power supply voltage is lowered by the abnormality detection resistor 73 is applied to the abnormality detection point 74, and a low potential abnormality is applied to the non-inverting input Vin + of the comparator 71 via the determination voltage acquisition line L6. The judgment voltage is input. At this time, since the reference voltage generation semiconductor switch 82 is off, substantially the same voltage (H level) as that of the comparator feeding line L3 is applied to the inverting input Vin− of the comparator 71. That is, since "Vin-> Vin +", the output Vout of the comparator 71 remains at the L level, the semiconductor switch 72 for normal operation keeps off, and the gate voltage Vg of the sub switch element 60 is at the H level. Therefore, the sub-semiconductor switch 60 also keeps off.

次いで、内燃機関用点火装置１が異常な状態において、点火信号Ｓｉが入力されると（信号レベルがＨに変わると）、イグナイタ制御回路５０から駆動信号が主半導体スイッチ３０のゲートに入力される。しかしながら、主半導体スイッチ３０は短絡異常で、既に一次コイル１１から接地点ＧＮＤに至る通電路は閉じている。同時に、基準電圧生成用半導体スイッチ８２がオンとなって第２分圧線Ｌ８ｂが接地点ＧＮＤに接続され、比較器７１の反転入力線Ｌ７には、第１，第２抵抗８１ａ，８１ｂの分圧比に応じた電圧（Ｌレベル）が印加される。しかしながら、比較器７１の非反転入力Ｖｉｎ＋に入力されているのは、低電位の異常判定電圧であるから、「Ｖｉｎ−＞Ｖｉｎ＋」が保持され、比較器７１の出力ＶｏｕｔはＬレベルを保持する。よって、正常動作用半導体スイッチ７２はオフを保持し、副スイッチ素子６０のゲート電圧ＶｇはＨレベルであるから、副半導体スイッチ６０もオフを保持する。 Next, when the ignition signal Si is input (when the signal level changes to H) in the ignition device 1 for the internal combustion engine in an abnormal state, a drive signal is input from the igniter control circuit 50 to the gate of the main semiconductor switch 30. .. However, the main semiconductor switch 30 has a short-circuit abnormality, and the energizing path from the primary coil 11 to the grounding point GND is already closed. At the same time, the reference voltage generation semiconductor switch 82 is turned on, the second voltage dividing line L8b is connected to the grounding point GND, and the inverting input line L7 of the comparator 71 is connected to the first and second resistors 81a and 81b. A voltage (L level) corresponding to the pressure ratio is applied. However, since it is the low potential abnormality determination voltage that is input to the non-inverting input Vin + of the comparator 71, "Vin-> Vin +" is held, and the output Vout of the comparator 71 holds the L level. .. Therefore, the semiconductor switch 72 for normal operation keeps off, and since the gate voltage Vg of the sub-switch element 60 is H level, the sub-semiconductor switch 60 also keeps off.

このように、フェールセーフ手段７０は、異常検出用抵抗７３を備えたバイパス線路Ｌ５を設けることで、異常検出点７４の電位レベルから主半導体スイッチ３０の異常状態を検出し、副半導体スイッチ６０のオン動作を規制できる。点火信号Ｓｉによる通電タイミングであっても、副半導体スイッチ６０のオン動作を規制することで、一次電流Ｉ１を抑制すれば、一次コイル１１からの熱放散が抑えられ、温度低下に伴って主半導体スイッチ３０が正常状態へ戻る可能性を高められる。 In this way, the fail-safe means 70 detects the abnormal state of the main semiconductor switch 30 from the potential level of the abnormality detection point 74 by providing the bypass line L5 provided with the abnormality detection resistor 73, and the sub-semiconductor switch 60. On operation can be regulated. Even at the energization timing by the ignition signal Si, if the primary current I1 is suppressed by restricting the on operation of the sub-semiconductor switch 60, heat dissipation from the primary coil 11 can be suppressed, and the main semiconductor as the temperature drops. The possibility that the switch 30 returns to the normal state is increased.

そして、主半導体スイッチ３０の短絡異常が解消されて正常状態に戻ったときには、一次コイル１１から接地点ＧＮＤへの通電路が遮断されるので、異常検出点７４の電位レベルから主半導体スイッチ３０が正常状態へ復帰したことを検出できる。主半導体スイッチ３０が正常状態に戻っていれば、点火信号Ｓｉの入力時には、副半導体スイッチ６０のオン動作が規制されることはないので、通常通り、一次コイル１１への通電・遮断制御が実行される。すなわち、フェールセーフ手段７０を用いれば、異常状態を回避するためにフェールセーフ機能が働いた後でも、正常状態へ自動復帰できるのである。 Then, when the short-circuit abnormality of the main semiconductor switch 30 is resolved and the normal state is restored, the energization path from the primary coil 11 to the grounding point GND is cut off, so that the main semiconductor switch 30 starts from the potential level of the abnormality detection point 74. It can be detected that it has returned to the normal state. If the main semiconductor switch 30 has returned to the normal state, the on operation of the sub-semiconductor switch 60 is not restricted when the ignition signal Si is input, so that the primary coil 11 is energized / cut off as usual. Will be done. That is, if the fail-safe means 70 is used, it is possible to automatically return to the normal state even after the fail-safe function is activated in order to avoid the abnormal state.

なお、上述した内燃機関用点火装置１では、副半導体スイッチ６０としてＰ型ＭＯＳＦＥＴを用いたが、これに限定されるものではない。例えば、副半導体スイッチ６０としてＰＮＰ型で高耐圧のＰＮＰパワートランジスタを用いても良い。斯くする場合、主半導体スイッチ３０が正常状態のときは、点火信号Ｓｉと同期してＰＮＰパワートランジスタのベース−エミッタ間電圧を低減させて、直流電源２０から一次コイル１１への通電路を閉じる。また、主半導体スイッチ３０が異常状態のときは、ＰＮＰパワートランジスタのベース−エミッタ間電圧を通常電圧に保持することで、ＰＮＰパワートランジスタのオン動作を規制できる。 In the above-mentioned ignition device 1 for an internal combustion engine, a P-type MOSFET is used as the sub-semiconductor switch 60, but the present invention is not limited to this. For example, a PNP type PNP power transistor having a high withstand voltage may be used as the sub-semiconductor switch 60. In this case, when the main semiconductor switch 30 is in the normal state, the base-emitter voltage of the PNP power transistor is reduced in synchronization with the ignition signal Si, and the energization path from the DC power supply 20 to the primary coil 11 is closed. Further, when the main semiconductor switch 30 is in an abnormal state, the ON operation of the PNP power transistor can be regulated by holding the base-emitter voltage of the PNP power transistor at a normal voltage.

副半導体スイッチ６０としてＰＮＰ型で高耐圧のＰＮＰパワートランジスタを用いる場合のフェールセーフ手段７０は、副半導体スイッチ６０として、Ｐ型ＭＯＳＦＥＴを用いる場合と同様に構成できる。異常検出用抵抗７３を備えるバイパス線路Ｌ５は、ＰＮＰパワートランジスタのコレクタ−エミッタ間を接続するように設ければ良い。比較器７１の非反転入力Ｖｉｎ＋に入力される異常判定電圧を取得するための判定電圧取得線Ｌ６は、ＰＮＰパワートランジスタと一次コイル１１との間に設けた異常検出点と接続すれば良い。そして、比較器７１が正常判定として出力ＶｏｕｔをＨレベルにすると、ＰＮＰパワートランジスタのベースから接地点ＧＮＤに至る通電路を開閉する正常動作用半導体スイッチ７２がオンとなって、直流電源２０から一次コイル１１への通電回路が閉じるのである。 The fail-safe means 70 when a PNP type PNP power transistor having a high withstand voltage is used as the sub-semiconductor switch 60 can be configured in the same manner as when a P-type MOSFET is used as the sub-semiconductor switch 60. The bypass line L5 provided with the abnormality detection resistor 73 may be provided so as to connect the collector and the emitter of the PNP power transistor. The determination voltage acquisition line L6 for acquiring the abnormality determination voltage input to the non-inverting input Vin + of the comparator 71 may be connected to an abnormality detection point provided between the PNP power transistor and the primary coil 11. Then, when the comparator 71 sets the output Vout to H level as a normal determination, the semiconductor switch 72 for normal operation that opens and closes the energizing path from the base of the PNP power transistor to the grounding point GND is turned on, and the DC power supply 20 is primary. The energization circuit to the coil 11 is closed.

上述した本実施形態の内燃機関用点火装置１では、主半導体スイッチ３０を点火コイル１０の接地側に設け、副半導体スイッチ６０を点火コイル１０の電源側に設けているため、異常検出によりフェールセーフ手段７０が作動しても、主半導体スイッチ３０の接地側が浮いた状態にならない。このため、一次コイル１１への通電により蓄えられたエネルギーは短絡異常が生じた主半導体スイッチ３０から接地点ＧＮＤへの電流として消費され、イグナイタ制御回路５０やフェールセーフ手段７０等の内部回路を破損してしまうような事態を避けられる。 In the ignition device 1 for an internal combustion engine of the present embodiment described above, since the main semiconductor switch 30 is provided on the ground side of the ignition coil 10 and the sub-semiconductor switch 60 is provided on the power supply side of the ignition coil 10, fail-safe by detecting an abnormality. Even if the means 70 operates, the ground side of the main semiconductor switch 30 does not float. Therefore, the energy stored by energizing the primary coil 11 is consumed as a current from the main semiconductor switch 30 where the short-circuit abnormality has occurred to the grounding point GND, and the internal circuits such as the igniter control circuit 50 and the fail-safe means 70 are damaged. You can avoid the situation that you end up doing.

また、本実施形態の内燃機関用点火装置１では、副半導体スイッチ６０のドレイン−ソース間を短絡するバイパス線路Ｌ５に異常検出用抵抗７３を設け、その抵抗から異常検出を行うものとしたので、サージ・ノイズの影響を受け易いリークチェック出力パルスを使う必要が無い。すなわち、リークチェック出力パルスによる異常チェックは、高インピーダンス状態で行う必要があり、サージ・ノイズの影響を受けやすく、誤判定が生じ易いという問題があるのに対して、フェールセーフ手段７０の異常検知では、そのような不具合は生じない。 Further, in the ignition device 1 for an internal combustion engine of the present embodiment, an abnormality detection resistor 73 is provided in the bypass line L5 short-circuiting between the drain and the source of the sub-semiconductor switch 60, and the abnormality is detected from the resistor. There is no need to use a leak check output pulse that is susceptible to surge noise. That is, the abnormality check by the leak check output pulse needs to be performed in a high impedance state, and has a problem that it is easily affected by surge noise and erroneous determination is likely to occur, whereas the abnormality detection of the fail-safe means 70 Then, such a defect does not occur.

さらに、本実施形態の内燃機関用点火装置１では、正常か異常かを判定する基準となる基準電圧信号を、定電流源などを用いず、点火信号Ｓｉのオン・オフに応じて生成する。正常状態で点火信号Ｓｉがオンのときには「Ｖｉｎ−＜Ｖｉｎ＋」が成立して副半導体スイッチ６０が動作し、正常状態でも点火信号Ｓｉがオフのときには「Ｖｉｎ−＞Ｖｉｎ＋」であるから、副半導体スイッチ６０の動作が規制される。一方、異常状態のときには、点火信号Ｓｉがオンでもオフでも「Ｖｉｎ−＞Ｖｉｎ＋」が成立するので、副半導体スイッチ６０の動作は規制され続ける。すなわち、点火信号Ｓｉのオン・オフにかかわらず、主半導体スイッチ３０の異常監視を常に行うことができる。 Further, in the ignition device 1 for an internal combustion engine of the present embodiment, a reference voltage signal as a reference for determining whether it is normal or abnormal is generated according to on / off of the ignition signal Si without using a constant current source or the like. When the ignition signal Si is on in the normal state, "Vin- <Vin +" is established and the sub-semiconductor switch 60 operates. Even in the normal state, when the ignition signal Si is off, "Vin-> Vin +" is established. The operation of the switch 60 is restricted. On the other hand, in the abnormal state, "Vin-> Vin +" is established regardless of whether the ignition signal Si is on or off, so that the operation of the sub-semiconductor switch 60 continues to be regulated. That is, the abnormality monitoring of the main semiconductor switch 30 can always be performed regardless of whether the ignition signal Si is turned on or off.

以上、本発明に係る内燃機関用点火装置の実施形態を添付図面に基づいて説明したが、本発明は、この実施形態に限定されるものではなく、特許請求の範囲に記載の構成を変更しない範囲で、公知既存の等価な技術手段を転用することにより実施しても構わない。 Although the embodiment of the ignition device for an internal combustion engine according to the present invention has been described above with reference to the accompanying drawings, the present invention is not limited to this embodiment and does not change the configuration described in the claims. To the extent, it may be carried out by diverting known and existing equivalent technical means.

１ 内燃機関用点火装置
１０ 点火コイル
１１ 一次コイル
１２ 二次コイル
２０ 直流電源
３０ 主半導体スイッチ
４０ ＥＣＵ
５０ イグナイタ制御回路
６０ 副半導体スイッチ
７０ フェールセーフ手段
８０ 基準電圧生成手段 1 Ignition system for internal combustion engine 10 Ignition coil 11 Primary coil 12 Secondary coil 20 DC power supply 30 Main semiconductor switch 40 ECU
50 Igniter control circuit 60 Sub-semiconductor switch 70 Fail-safe means 80 Reference voltage generation means

Claims (6)

点火サイクルの所要タイミングで入力される点火信号に基づいて、点火コイルの一次コイルに流れる一次電流を通電・遮断制御し、二次側に高電圧を発生させる内燃機関用点火装置において、
前記一次コイルと接地点との間に設けられ、前記点火信号のオン・オフに応じて一次コイルから接地点への通電路を開閉する主半導体スイッチと、
前記一次コイルと電源との間に設けられ、該電源から前記一次コイルへの通電路を開閉する副半導体スイッチと、
前記主半導体スイッチの異常状態を検出することに基づいて、前記副半導体スイッチのオン動作を規制するフェールセーフ手段と、
を備えることを特徴とする内燃機関用点火装置。 In an ignition device for an internal combustion engine that generates a high voltage on the secondary side by energizing and shutting off the primary current flowing through the primary coil of the ignition coil based on the ignition signal input at the required timing of the ignition cycle.
A main semiconductor switch provided between the primary coil and the grounding point that opens and closes an energizing path from the primary coil to the grounding point according to the on / off of the ignition signal.
An auxiliary semiconductor switch provided between the primary coil and the power supply that opens and closes an energizing path from the power supply to the primary coil.
A fail-safe means for regulating the on-operation of the sub-semiconductor switch based on detecting an abnormal state of the main semiconductor switch,
An ignition device for an internal combustion engine, which comprises. 前記フェールセーフ手段は、前記主半導体スイッチが異常状態から正常状態へ復帰したことを検出することに基づいて、前記副半導体スイッチのオン動作規制を解除することを特徴とする請求項１に記載の内燃機関用点火装置。 The first aspect of claim 1, wherein the fail-safe means releases the on-operation restriction of the sub-semiconductor switch based on detecting that the main semiconductor switch has returned from the abnormal state to the normal state. Ignition system for internal combustion engines. 前記副半導体スイッチとして、Ｐ型ＭＯＳＦＥＴを用い、
前記フェールセーフ手段は、前記主半導体スイッチが正常状態のとき、前記点火信号と同期して前記副半導体スイッチのゲート−ソース間電圧を低減させて、電源から前記一次コイルへの通電路を閉じ、前記主半導体スイッチが異常状態のとき、前記副半導体スイッチのゲート−ソース間電圧を通常電圧に保持することを特徴とする請求項１又は請求項２に記載の内燃機関用点火装置。 A P-type MOSFET is used as the sub-semiconductor switch.
When the main semiconductor switch is in a normal state, the fail-safe means reduces the gate-source voltage of the sub-semiconductor switch in synchronization with the ignition signal to close the energizing path from the power supply to the primary coil. The ignition device for an internal combustion engine according to claim 1 or 2, wherein the gate-source voltage of the sub-semiconductor switch is maintained at a normal voltage when the main semiconductor switch is in an abnormal state. 前記フェールセーフ手段は、
前記副半導体スイッチのドレイン−ソース間を接続する異常検出用抵抗と、
前記副半導体スイッチと前記一次コイルとの間に設けた異常検出点の電圧を取得する判定電圧取得線と、
前記判定電圧取得線から取得した異常判定電圧と、正常判定閾値である基準電圧とを比較して、正常判定の場合にのみ正常信号を出力する比較器と、
前記副半導体スイッチのゲートから前記接地点に至る通電路に設けられ、前記比較器からの正常信号が入力されることで、前記副半導体スイッチのゲートから前記接地点に至る通電路を閉じる正常動作用半導体スイッチと、
を備えることを特徴とする請求項３に記載の内燃機関用点火装置。 The fail-safe means
Anomaly detection resistor connecting the drain and source of the sub-semiconductor switch,
A determination voltage acquisition line for acquiring the voltage of the abnormality detection point provided between the sub-semiconductor switch and the primary coil, and
A comparator that compares the abnormality judgment voltage acquired from the judgment voltage acquisition line with the reference voltage which is the normal judgment threshold value and outputs a normal signal only in the case of normal judgment.
A normal operation is provided in the energizing path from the gate of the sub-semiconductor switch to the grounding point, and the energizing path from the gate of the sub-semiconductor switch to the grounding point is closed by inputting a normal signal from the comparator. Semiconductor switch for
The ignition device for an internal combustion engine according to claim 3, wherein the ignition device is provided. 前記副半導体スイッチとして、ＰＮＰ型で高耐圧のＰＮＰパワートランジスタを用い、
前記フェールセーフ手段は、前記主半導体スイッチが正常状態のとき、前記点火信号と同期して前記副半導体スイッチのベース−エミッタ間電圧を低減させて、電源から前記一次コイルへの通電路を閉じ、前記主半導体スイッチが異常状態のとき、前記副半導体スイッチのベース−エミッタ間電圧を通常電圧に保持することを特徴とする請求項１又は請求項２に記載の内燃機関用点火装置。 A PNP type high withstand voltage PNP power transistor is used as the sub-semiconductor switch.
When the main semiconductor switch is in a normal state, the fail-safe means reduces the base-emitter voltage of the sub-semiconductor switch in synchronization with the ignition signal to close the energization path from the power supply to the primary coil. The ignition device for an internal combustion engine according to claim 1 or 2, wherein when the main semiconductor switch is in an abnormal state, the base-emitter voltage of the sub-semiconductor switch is held at a normal voltage. 前記フェールセーフ手段は、
前記副半導体スイッチのコレクタ−エミッタ間を接続する異常検出用抵抗と、
前記副半導体スイッチと前記一次コイルとの間に設けた異常検出点の電圧を取得する判定電圧取得線と、
前記判定電圧取得線から取得した異常判定電圧と、正常判定閾値である基準電圧とを比較して、正常判定の場合にのみ正常信号を出力する比較器と、
前記副半導体スイッチのベースから前記接地点に至る通電路に設けられ、前記比較器からの正常信号が入力されることで、前記副半導体スイッチのベースから前記接地点に至る通電路を閉じる正常動作用半導体スイッチと、
を備えることを特徴とする請求項５に記載の内燃機関用点火装置。 The fail-safe means
Anomaly detection resistor connecting the collector and emitter of the sub-semiconductor switch,
A determination voltage acquisition line for acquiring the voltage of the abnormality detection point provided between the sub-semiconductor switch and the primary coil, and
A comparator that compares the abnormality judgment voltage acquired from the judgment voltage acquisition line with the reference voltage which is the normal judgment threshold value and outputs a normal signal only in the case of normal judgment.
A normal operation is provided in the energizing path from the base of the sub-semiconductor switch to the grounding point, and the energizing path from the base of the sub-semiconductor switch to the grounding point is closed by inputting a normal signal from the comparator. Semiconductor switch for
The ignition device for an internal combustion engine according to claim 5, wherein the ignition device is provided.
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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5374529U (en) * 1976-11-24 1978-06-21
JP2002061558A (en) * 2000-08-21 2002-02-28 Kokusan Denki Co Ltd Ignition device for internal combustion engine
JP2002157027A (en) * 2000-11-20 2002-05-31 Mitsubishi Electric Corp Power conversion device and semiconductor device
JP2002303238A (en) * 2001-04-05 2002-10-18 Nippon Soken Inc Ignition device for internal combustion engine
JP2003314419A (en) * 2002-04-26 2003-11-06 Kokusan Denki Co Ltd Ignition device for internal combustion engine
US9745947B2 (en) * 2013-08-08 2017-08-29 Fairchild Semiconductor Corporation Ignition control circuit with short circuit protection

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5374529U (en) * 1976-11-24 1978-06-21
JP2002061558A (en) * 2000-08-21 2002-02-28 Kokusan Denki Co Ltd Ignition device for internal combustion engine
JP2002157027A (en) * 2000-11-20 2002-05-31 Mitsubishi Electric Corp Power conversion device and semiconductor device
JP2002303238A (en) * 2001-04-05 2002-10-18 Nippon Soken Inc Ignition device for internal combustion engine
JP2003314419A (en) * 2002-04-26 2003-11-06 Kokusan Denki Co Ltd Ignition device for internal combustion engine
US9745947B2 (en) * 2013-08-08 2017-08-29 Fairchild Semiconductor Corporation Ignition control circuit with short circuit protection

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