JP3979305B2 - Method and apparatus for detecting spark plug gap in internal combustion engine - Google Patents

Description

【００５４】
即ち、点火プラグ２１の放電ギャップ２１ａの大きさが正規であれば、圧縮行程では気筒１１の燃焼室内が高圧となるため、単独放電時間が「短」となり、排気行程では気筒１１の燃焼室内が低圧となるため、単独放電時間が「中」となる。一方、点火プラグ２１の放電ギャップ２１ａが小さければ、圧縮行程では気筒１１の燃焼室内が高圧となるため、単独放電時間が「中」となり、排気行程では気筒１１の燃焼室内が低圧となるため、単独放電時間が「長」となる。また、圧縮行程、排気行程の何れにおいても、放電ギャップ２１ａが正規の場合に比べて小さい場合の方が、単独放電時間が短くなっている。
【００５５】
ところが、例えば第１気筒１１の第１点火プラグ２１の放電ギャップ２１ａが正規の大きさで、第４気筒１４の第４点火プラグ２４の放電ギャップ２４ａが小さい場合、これらの点火プラグ２１，２４を同じ圧力条件（例えば気筒１１，１４の燃焼室内が同じ大気圧の状態）で同時に放電させると、表２に示すように単独放電時間は第１点火プラグ２１が「中」、第４点火プラグ２４が「長」であるが、合成放電時間は「中」となってしまう。
【００５６】
【表２】

【００５７】
即ち、正規の（大きい）放電ギャップ２１ａを有する第１点火プラグ２１の方が、小さい放電ギャップ２４ａを有する第４点火プラグ２４に比べて単独放電時間が短いことから、合成放電時間においては第１点火プラグ２１の方が支配的となり、合成放電時間には第４点火プラグ２４の放電ギャップ２４ａが小さくなっていることの影響が現れない。つまり、両方の点火プラグ２１，２４とも放電ギャップ２１ａ，２４ａが正規の大きさである場合に比べて、合成放電時間に差が生ぜず、この場合には第１検出用コイル５１による二次電圧信号の出力波形から放電時間Ｔや振幅Ｈを求めても、第４点火プラグ２４の放電ギャップ２４ａが小さくなっていることを検出することはできない。
【００５８】
そこで、本実施の形態では上記のようにモータ５４で内燃機関１０を回転させながら、点火プラグ２１，２４を同時に放電させるようした（図３参照）。この場合には、例えば第１気筒１１の第１点火プラグ２１の放電ギャップ２１ａが正規の大きさで、第４気筒１４の第４点火プラグ２４の放電ギャップ２４ａが小さくなっているときには、表３に示すような放電時間となる。
【００５９】
【表３】

【００６０】
即ち、第１点火プラグ２１を圧縮行程（高圧下）で放電させるときには、同時に第４点火プラグ２４は排気行程（低圧下）で放電させることになり、このときには正規の大きさの放電ギャップ２１ａを有する第１点火プラグ２１の単独放電時間は「短」、小さい放電ギャップ２４ａを有する第４点火プラグ２４の単独放電時間は「長」であるため、放電ギャップの大きい第１点火プラグ２１の方が支配的となり、合成放電時間は「短」となる。つまり、この放電時における第１イグニッションコイル３１の二次電圧信号の波形は、第１点火プラグ２１の放電ギャップ２１ａの大きさを反映したものとなる。
【００６１】
続いて、第４点火プラグ２４を圧縮行程（高圧下）で放電させると、同時に第１点火プラグ２１は排気行程（低圧下）で放電させることになる。そして、このときには正規の大きさの放電ギャップ２１ａを有する第１点火プラグ２１の単独放電時間は「中」、小さい放電ギャップ２４ａを有する第４点火プラグ２４の単独放電時間も「中」であるため、合成放電時間も「中」となる。即ち、第４点火プラグ２４を圧縮行程で放電させたときには、排気行程で放電させたときと放電時間に差が生じ、この放電時における第１イグニッションコイル３１の二次電圧信号の波形は、第４点火プラグ２４の放電ギャップ２４ａの大きさを反映したものとなる。
【００６２】
同様に、第４点火プラグ２４の放電ギャップ２４ａは正規の大きさで、第１点火プラグ２１の放電ギャップ２１ａが小さくなっている場合には、第１点火プラグ２１を排気行程（低圧下）で放電させたときの合成放電時間（短）と、圧縮行程（高圧下）で放電させたときの合成放電時間（中）とに差が生じ、前者の合成放電時間（第１イグニッションコイル３１の二次電圧信号の波形）は第４点火プラグ２４の放電ギャップ２４ａ大きさを反映したものであるが、後者の合成放電時間（第１イグニッションコイル３１の二次電圧信号の波形）は第１点火プラグ２１の放電ギャップ２１ａの大きさを反映したものとなる。
【００６３】
また、詳細な説明は省略するが、他の同じ組の点火プラグ２２,２３についても、モータ５４で内燃機関１０を回転させながら、点火プラグ２２，２３を同時に放電させれば、第２点火プラグ２２の放電ギャップ２２ａが正規の大きさで第３点火プラグ２３の放電ギャップ２３ａが小さくなっている場合や、第３点火プラグ２３の放電ギャップ２３ａが正規の大きさで第２点火プラグ２２の放電ギャップ２２ａが小さくなっている場合にも、上記点火プラグ２１,２４の場合と同様になる。即ち、放電ギャップの小さい第３点火プラグ２３、或いは、放電ギャップの小さい第２点火プラグ２２が、排気行程（低圧下）で放電するときと圧縮行程（高圧下）で放電するときとで合成放電時間に差が生じ、前者の合成放電時間（第２イグニッションコイル３２の二次電圧信号の波形）は、大きい方の第２点火プラグ２２の放電ギャップ２２ａの大きさ、或いは、大きい方の第３点火プラグ２３の放電ギャップ２３ａ大きさを反映したものであるが、後者の合成放電時間（第２イグニッションコイル３２の二次電圧信号の波形）は、小さい方の第３点火プラグ２３の放電ギャップ２３ａの大きさ、或いは、小さい方の第２点火プラグ２２の放電ギャップ２２ａの大きさを反映したものとなる。
【００６４】
そこで、検査ユニット５３では、前述のようにクランク角センサ５５の回転角検出信号を入力し、この回転角検出信号に基づいて点火プラグ２１，２４の放電時や、点火プラグ２２，２３の放電時に圧縮行程にある気筒１１，１２，１３又は１４を判別し、この判別機能により圧縮行程にあると判別された気筒１１，１２，１３又は１４に組み付けられている点火プラグ２１，２２，２３又は２４の放電ギャップ２１ａ，２２ａ，２３ａ又は２４ａを、このときに検出用コイル５１又は５１で検出される第１イグニッションコイル３１又は第２イグニッションコイル３２の二次電圧信号の出力波形に基づいて検出する。即ち、前記出力波形から放電時間Ｔや振幅Ｈ（何れか一方だけでもよい）を求めて、点火プラグ２１，２２，２３，２４の放電ギャップ２１ａ，２２ａ，２３ａ，２４ａの良否判定を行う。
【００６５】
従って、本実施の形態によれば、セミダイレクト点火方式の点火系を有する内燃機関１０に対しても、各気筒１１，１２，１３，１４の点火プラグ２１，２２，２３，２４の放電ギャップ２１ａ，２２ａ，２３ａ，２４ａを確実に検出することができる。しかも、点火プラグだけでなく、イグニッションコイルなどを含めた点火系全体の保証（検査）が可能である。実際にセミダイレクト点火方式の点火系を有する内燃機関に対して、本発明の装置で検査を行った結果、同じ組の２つの点火プラグのうち、例えば一方の点火プラグの放電ギャップが正規の大きさ（１．１ｍｍ）で、他方の点火プラグプラグの放電ギャップが０．３ｍｍ以下であれば、この不良品の点火プラグをほぼ１００％検出可能であることを確認している。勿論、０．３ｍｍ以上であっても検出は可能である。
【００６６】
なお、上記では４気筒のセミダイレクト点火方式の内燃機関を検査する場合について説明したが、これに限定するものではなく、本発明は他の気筒数（例えば６気筒）のセミダイレクト点火方式の内燃機関を検査する場合にも適用することができる。
【００６７】
また、上記ではモータ５４によって内燃機関１０（クランクシャフト）を回転させているが（モータリング運転）、必ずしもこれに限定するものではなく、実際に各気筒に燃料を供給して点火する所謂ファイアリング運転によって内燃機関１０を回転させてもよい。但し、モータリング運転の方が、ファイアリング運転に比べて、気筒１１，１２，１３，１４の燃焼室内の気流の状態などが安定して、放電状態も安定するため、より確実に点火プラグ２１，２２，２３，２４の放電ギャップ２１ａ，２２ａ，２３ａ，２４ａを検出することができる。
【００６８】
また、上記では同じ組の２つの点火プラグの放電ギャップの一方が正規で他方が小さい場合について説明したが、必ずしもこれに限定するものではなく、本発明では、例えば前記２つの点火プラグの放電ギャップの一方が正規で他方が大きい場合にも放電ギャップの検出が可能である。
【００６９】
【発明の効果】
以上、発明の実施の形態とともに具体的に説明したように、第１発明の内燃機関の点火プラグギャップ検出方法によれば、複数の気筒を２つずつ複数の組に分け、同じ組の２つの気筒の点火プラグを同一のイグニッションコイルの二次側に電気的に接続して同時に放電させるセミダイレクト点火方式の点火系を備えた内燃機関の点火プラグギャップ検出方法であって、前記内燃機関を回転させながら前記同じ組の２つの気筒の点火プラグを同時に放電させ、この放電時における前記イグニッションコイルの二次電圧信号の波形を検出してモニターし、且つ、前記放電時に圧縮行程にある気筒を判別して、この圧縮行程にあると判別された気筒に組み付けられている点火プラグの放電ギャップを、前記二次電圧信号の波形に基づいて検出することを特徴とするため、セミダイレクト点火方式の点火系を有する内燃機関に対しても、各気筒の点火プラグの放電ギャップを確実に検出することができる。例えば同じ組の２つの点火プラグの放電ギャップの一方が正規の大きさで他方が小さい場合でも、この小さい点火プラグの放電ギャップを確実に検出することができる。
【００７０】
また、第２発明の内燃機関の点火プラグギャップ検出方法によれば、第１発明の内燃機関の点火プラグギャップ検出方法において、前記内燃機関をモータによって回転させることを特徴とするため、ファイアリング運転に比べて、気筒の燃焼室内の気流の状態などが安定して、放電状態も安定するため、より確実に点火プラグの放電ギャップを検出することができる。
【００７１】
また、第３発明の内燃機関の点火プラグギャップ検出方法によれば、第１又は第２発明の内燃機関の点火プラグギャップ検出方法において、前記二次電圧信号を、前記イグニッションコイルの近傍に設けた検出用コイルにより検出してモニターすることを特徴とするため、イグニッションコイルに対して電気的に非接触で前記二次電圧信号を検出することができ、内燃機関にイグニッションコイルなどの点火系の構成部品を全て組み込んだ状態で、実際の点火系による放電に基づいて点火プラグの放電ギャップの検出が可能となる。このため、点火プラグだけでなく、イグニッションコイルなどを含めた点火系全体の保証（検査）が可能である。
【００７２】
また、第４発明の内燃機関の点火プラグギャップ検出装置によれば、複数の気筒を２つずつ複数の組に分け、同じ組の２つの気筒の点火プラグを同一のイグニッションコイルの二次側に電気的に接続して同時に放電させるセミダイレクト点火方式の点火系を備えた内燃機関の点火プラグギャップ検出装置であって、内燃機関を回転させる回転手段と、この回転手段によって前記内燃機関を回転させながら前記同じ組の２つの気筒の点火プラグを同時に放電させる放電制御手段と、この放電時における前記イグニッションコイルの二次電圧信号を検出する二次電圧信号検出手段と、この二次電圧信号検出手段で検出される前記二次電圧信号の波形をモニターする波形モニター手段と、前記放電時に圧縮行程にある気筒を判別する気筒判別手段と、この気筒判別手段により圧縮行程にあると判別された気筒に組み付けられている点火プラグの放電ギャップを、前記二次電圧信号の波形に基づいて検出するギャップ検出手段とを備えたことを特徴とするため、セミダイレクト点火方式の点火系を有する内燃機関に対しても、各気筒の点火プラグの放電ギャップを確実に検出することができる。例えば同じ組の２つの点火プラグの放電ギャップの一方が正規の大きさで他方が小さい場合でも、この小さい点火プラグの放電ギャップを確実に検出することができる。
【００７３】
また、第５発明の内燃機関の点火プラグギャップ検出装置によれば、第４発明の内燃機関の点火プラグギャップ検出装置において、前記回転手段はモータであことを特徴とするため、ファイアリング運転に比べて、気筒の燃焼室内の気流の状態などが安定して、放電状態も安定するため、より確実に点火プラグの放電ギャップを検出することができる。
【００７４】
また、第６発明の内燃機関の点火プラグギャップ検出装置によれば、第４又は第５発明の内燃機関の点火プラグギャップ検出装置において、前記二次電圧信号検出手段は前記イグニッションコイルの近傍に設けた検出用コイルであり、この検出用コイルで前記イグニッションコイルの二次側の放電による磁界の変化を捉えて前記二次電圧信号を検出することを特徴とするため、イグニッションコイルに対して電気的に非接触で前記二次電圧信号を検出することができ、内燃機関にイグニッションコイルなどの点火系の構成部品を全て組み込んだ状態で、実際の点火系による放電に基づいて点火プラグの放電ギャップの検出が可能となる。このため、点火プラグだけでなく、イグニッションコイルなどを含めた点火系全体の保証（検査）が可能である。
【図面の簡単な説明】
【図１】本発明の実施の形態に係る内燃機関の点火プラグギャップ検出装置による検査時の状態を示す構成図である。
【図２】検出用コイルの配置例を示す図である。
【図３】前記内燃機関の各気筒に組み付けた点火プラグの放電タイミングを表すチャートである。
【図４】二次電圧信号の出力波形を表すグラフである。
【図５】放電ギャップの良否判定を行うためのチャートである。
【図６】ダイレクト点火方式の点火系の構成図である。
【符号の説明】
１０ 内燃機関
１１，１２，１３，１４ 第１〜第４気筒
２１，２２，２３，２４ 第１〜第４点火プラグ
２１ａ，２２ａ，２３ａ，２４ａ 放電ギャップ
３１，３２ 第１，第２イグニッションコイル
３１Ａ，３２Ａ 二次コイル
３１Ｂ，３２Ｂ 一次コイル
３１Ｃ，３２Ｃ フェライトコア
３３ バッテリ
３４，３５ 第１，第２トランジスタ
３６ ＥＣＵ
５１，５２ 第１，第２検出用コイル
５３ 検査ユニット
５４ モータ
５５ クランク角センサ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spark plug gap detection method and apparatus for an internal combustion engine equipped with a semi-direct ignition system.
[0002]
[Prior art]
In an internal combustion engine such as an engine for a vehicle, as a conventional method or apparatus for detecting a discharge gap of a spark plug assembled in the cylinder (determining whether the discharge gap is good or bad), for example, the following Patent Document 1, Those disclosed in (2) and (3) are mentioned.
[0003]
[Patent Document 1]
Japanese Patent No. 3228159
[Patent Document 2]
Japanese Patent Publication No.56-54573
[Patent Document 3]
JP 2002-13460 A
[0004]
In the method disclosed in Patent Document 1, the primary voltage is applied to the spark plug based on the primary voltage in a state where the spark plug is assembled to the engine as described in the column of the claims. By applying a voltage sufficient to cause discharge by a discharge voltage application device that generates a higher secondary voltage, the primary voltage at that time is detected and a primary voltage related quantity related to the primary voltage is obtained, The state of the spark plug is determined based on the acquired primary voltage related quantity.
[0005]
The device disclosed in Patent Document 2 is an ignition device provided in an ignition system of an internal combustion engine for detecting a secondary voltage signal of the ignition system, as described in the appended claims. A probe including a voltage dividing device connected between the secondary coil of the niching coil and the distributor, and an inductive discharge portion in a secondary voltage signal detected by the probe, and the inductive discharge portion is electrically And a processing circuit for obtaining a time width signal of the induction discharge portion by processing the same, and detecting the time width signal of the induction discharge portion of the processing circuit output as a gap of the spark plug.
[0006]
The device disclosed in Patent Document 3 is disposed in the vicinity of an ignition coil of an ignition system assembled in an internal combustion engine, as described in the claims, etc., and is induced by the ignition coil. Detecting means for detecting a secondary voltage to be output and outputting a secondary voltage signal; monitoring means for monitoring an output waveform of the secondary voltage signal output from the detecting means; and a secondary side by the ignition coil And a determination means for reading back electromotive force generated at the end of the discharge from the output waveform of the secondary voltage signal and determining the quality of the discharge gap of the spark plug based on the amount of change. .
[0007]
[Problems to be solved by the invention]
However, in any of the methods and apparatuses of Patent Documents 1, 2, and 3, it is difficult to determine whether the discharge gap of the spark plug is good or bad for an internal combustion engine having a so-called semi-direct ignition system ignition system. there were.
[0008]
That is, for an internal combustion engine having a so-called direct ignition type ignition system in which one ignition plug 2 is electrically connected to one ignition coil 1 as shown in FIG. Any of the methods 2 and 3 can detect the discharge gap 2a of the spark plug 2 (determining whether it is good or bad).
[0009]
However, in the internal combustion engine 10 having the semi-direct ignition type ignition system as shown in FIG. 1, for example, the secondary of one ignition coil 31 with respect to the ignition plugs 21 and 24 of the two cylinders 11 and 14 of the same set. By simultaneously applying a voltage, these spark plugs 21 and 24 are discharged simultaneously (details will be described later). For this reason, when the pressure conditions in the combustion chambers of the first cylinder 11 and the second cylinder 14 during the discharge are the same, even if the discharge gap 24a of the spark plug 24 of the fourth cylinder 14 is small, for example, If the discharge gap 21a of the ignition plug 21 of the cylinder 11 is normal, the first ignition plug 21 having a larger discharge gap (that is, the one that is less likely to discharge) is dominant in the discharge. Even if the discharge time or the like is obtained from the primary voltage signal or the secondary voltage signal, the discharge gap 24a of the fourth spark plug 24 cannot be detected. That is, it cannot be found that the discharge gap 24a of the fourth spark plug 24 is small.
[0010]
Accordingly, in view of the above circumstances, it is an object of the present invention to provide an internal combustion engine spark plug gap detection method and apparatus capable of reliably detecting an ignition plug gap of an internal combustion engine having a semi-direct ignition system ignition system. And
[0011]
[Means for Solving the Problems]
An ignition plug gap detection method for an internal combustion engine according to a first aspect of the present invention that solves the above-described problem is that a plurality of cylinders are divided into a plurality of groups each including two cylinders, and the ignition plugs of two cylinders of the same group are connected to the secondary side of the same ignition coil A spark plug gap detection method for an internal combustion engine having a semi-direct ignition system ignition system that is electrically connected to and discharges simultaneously, wherein the ignition plugs of the two cylinders of the same set are rotated while the internal combustion engine is rotated. Cylinders that are discharged at the same time, detect and monitor the waveform of the secondary voltage signal of the ignition coil at the time of this discharge, determine the cylinder that is in the compression stroke at the time of the discharge, and are determined to be in this compression stroke The discharge gap of the spark plug assembled in the is detected based on the waveform of the secondary voltage signal.
[0012]
An ignition plug gap detection method for an internal combustion engine according to a second aspect of the invention is the ignition plug gap detection method for an internal combustion engine according to the first aspect, wherein the internal combustion engine is rotated by a motor.
[0013]
An ignition plug gap detection method for an internal combustion engine according to a third invention is the detection plug gap detection method for an internal combustion engine according to the first or second invention, wherein the secondary voltage signal is provided in the vicinity of the ignition coil. It is detected and monitored by a coil.
[0014]
The spark plug gap detecting device for an internal combustion engine according to the fourth aspect of the present invention divides a plurality of cylinders into a plurality of groups each two, and electrically connects the spark plugs of two cylinders of the same group to the secondary side of the same ignition coil. An ignition plug gap detecting device for an internal combustion engine having a semi-direct ignition type ignition system that is connected to and simultaneously discharging, rotating means for rotating the internal combustion engine, and rotating the internal combustion engine by the rotating means Discharge control means for simultaneously discharging spark plugs of two cylinders of the same set, secondary voltage signal detection means for detecting a secondary voltage signal of the ignition coil at the time of this discharge, and detection by this secondary voltage signal detection means Waveform monitoring means for monitoring the waveform of the secondary voltage signal, cylinder discrimination means for discriminating a cylinder in the compression stroke during the discharge, The discharge gap of the spark plug is assembled to the determined cylinder and the compression stroke by the cylinder discriminating means, and said and a gap detection means for detecting on the basis of the waveform of the secondary voltage signal.
[0015]
An ignition plug gap detection device for an internal combustion engine according to a fifth aspect of the present invention is the ignition plug gap detection device for an internal combustion engine according to the fourth aspect, wherein the rotating means is a motor.
[0016]
An ignition plug gap detection device for an internal combustion engine according to a sixth aspect of the invention is the ignition plug gap detection device for an internal combustion engine according to the fourth or fifth aspect, wherein the secondary voltage signal detection means is provided in the vicinity of the ignition coil. The detection coil detects a change in the magnetic field due to the discharge on the secondary side of the ignition coil and detects the secondary voltage signal.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the drawings.
[0018]
FIG. 1 is a configuration diagram showing a state at the time of inspection by an ignition plug gap detection device for an internal combustion engine according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of arrangement of detection coils, and FIG. FIG. 4 is a graph showing the output waveform of the secondary voltage signal, and FIG. 5 is a chart for determining whether the discharge gap is good or bad.
[0019]
As shown in FIG. 1, an internal combustion engine 10 such as a vehicle engine has first to fourth spark plugs 21, 22, 23, 24 in first to fourth cylinders 11, 12, 13, 14, respectively. It is in the assembled state. Reference numerals 21a, 22a, 23a, and 24a in FIG. 1 denote discharge gaps of the respective spark plugs 21, 22, 23, and 24, respectively. In FIG. 1, for convenience of explanation, the third cylinder 23, the second cylinder 22, the first cylinder 21, and the fourth cylinder 24 are illustrated in this order, but of course, the first cylinder 11 and the second cylinder 12 are actually shown. The third cylinder 13 and the fourth cylinder 14 are arranged in this order, and the ignition order is set to be the first cylinder 11, the third cylinder 13, the fourth cylinder 14, and the second cylinder 12.
[0020]
The ignition system of the internal combustion engine 10 has a so-called semi-direct ignition system configuration in which a plurality of cylinders are divided into a plurality of groups of two, and the spark plugs of the two cylinders of the same group are discharged simultaneously.
[0021]
More specifically, the four cylinders 11 to 14 are divided into two sets, a set of the first cylinder 11 and the fourth cylinder 14 and a set of the second cylinder 12 and the third cylinder 13. The first spark plug 21 of the first cylinder 11 has one electrode side electrically connected to one end side of the secondary coil 31A of the first ignition coil 31, and the other electrode side grounded. The fourth spark plug 24 of the fourth cylinder 14 has one electrode side electrically connected to the other end side of the secondary coil 31A of the first ignition coil 31, and the other electrode side grounded. For this reason, the 1st spark plug 21 and the 4th spark plug 24 are connected in series, and comprise one closed loop with the secondary coil 31A. That is, the spark plugs 21 and 24 of the two cylinders 11 and 14 in the same set are electrically connected to the secondary side of the same ignition coil 31 and are simultaneously discharged.
[0022]
The second ignition plug 22 of the second cylinder 12 has one electrode side electrically connected to one end side of the secondary coil 32A of the second ignition coil 32 and the other electrode side grounded. The third spark plug 23 of the third cylinder 13 has one electrode side electrically connected to the other end side of the secondary coil 32A of the second ignition coil 32 and the other electrode side grounded. For this reason, the 2nd spark plug 22 and the 3rd spark plug 23 are connected in series, and comprise one closed loop with the secondary coil 32A. That is, the spark plugs 22 and 23 of the two cylinders 12 and 13 in the same set are also electrically connected to the secondary side of the same ignition coil 32 and are simultaneously discharged.
[0023]
In the first ignition coil 31, the primary coil 31A and the secondary coil 31B are set to a predetermined turns ratio, and the primary voltage is boosted to obtain a high secondary voltage. In the second ignition coil 32, the primary coil 32A and the secondary coil 32B are set to a predetermined turns ratio, and the primary voltage is boosted to obtain a high-voltage secondary voltage.
[0024]
The primary coil 31B of the first ignition coil 31 has one end side electrically connected to the positive electrode side of the battery 33 and the other end side electrically connected to the collector of the first transistor 34. The negative electrode side of the battery 33 is grounded. The base of the first transistor 34 is electrically connected to an electronic control unit (ECU) 36 of the internal combustion engine, and the emitter of the first transistor 34 is grounded. The first ignition coil 31 and the first transistor 34 are integrally formed by molding.
[0025]
One end side of the primary coil 32 </ b> B of the second ignition coil 32 is electrically connected to the positive electrode side of the battery 33, and the other end side is electrically connected to the collector of the second transistor 35. The base of the second transistor 35 is electrically connected to the ECU 36, and the emitter of the second transistor 35 is grounded. Note that the second ignition coil 32 and the second transistor 35 are also integrally formed by molding.
[0026]
The ECU 36 controls the energization from the battery 33 to the primary coil 31B of the first ignition coil 31 by controlling the base current of the first transistor 34 to perform on / off control of the first transistor 34, thereby The secondary voltage induced in the secondary coil 31A of the ignition coil 31 is applied to the spark plugs 21 and 24 to control the timing of discharging the spark plugs 21 and 24, and the base current of the second transistor 35 is controlled. By controlling on / off control of the second transistor 35 to control energization from the battery 33 to the primary coil 32B of the second ignition coil 32, the second transistor 32A induced by the secondary coil 32A of the second ignition coil 32 is controlled. The next voltage is applied to the spark plugs 22 and 23 to discharge the spark plugs 22 and 23. Timing also controls.
[0027]
When the ignition system is inspected, a first detection coil 51 as a secondary voltage signal detection means is disposed in the vicinity of the first ignition coil 31, and as a secondary voltage signal detection means in the vicinity of the second ignition coil 32. A second detection coil 52 is arranged. At this time, the first detection coil 51 detects the change in the magnetic field induced by the secondary discharge of the first ignition coil 31 (discharge of the ignition plugs 21 and 24), and the secondary voltage of the first ignition coil 31 is detected. The second detection coil 52 captures changes in the magnetic field induced by the secondary discharge of the second ignition coil 32 (discharge of the ignition plugs 22 and 23), and It arrange | positions so that the secondary voltage of the 2 ignition coil 32 can be detected.
[0028]
For example, as shown in FIG. 2, with respect to the first ignition coil 31 having the primary coil 31B and the secondary coil 31A arranged around the ferrite core 31C, the first ignition coil 31 is directly above the first ignition coil 31. For the second ignition coil 32 having the primary coil 32B and the secondary coil 32A that are arranged around the ferrite core 32C in the same manner, the first detection coil 51 is disposed directly above the second ignition coil 32. The second detection coil 52 is disposed in
[0029]
Further, the first detection coil 51 and the second detection coil 52 are electrically connected to an inspection unit 53 that functions as a waveform monitoring unit, a cylinder discrimination unit, a gap detection unit, and the like.
[0030]
The first detection coil 51 converts the change in the magnetic field due to the discharge on the secondary side (secondary coil 31 </ b> A side) of the first ignition coil 31 into the change in voltage, and this voltage is converted into the secondary voltage of the first ignition coil 31. The second detection coil 52 converts the change in the magnetic field due to the discharge on the secondary side (secondary coil 32A side) of the second ignition coil 32 into a change in voltage. A secondary voltage signal of the two ignition coils 32 is output to the inspection unit 53.
[0031]
The inspection unit 53 has a function of displaying the secondary voltage signal from the detection coils 51 and 52 as, for example, a voltage waveform by a built-in oscilloscope or displaying numerically. A display device other than the oscilloscope may be used for the inspection unit 53. The inspection unit 53 also has a function of monitoring (monitoring) the output waveform of the secondary voltage signal in addition to these display functions (waveform monitoring means).
[0032]
Further, as will be described in detail later, the inspection unit 53 inputs a rotation angle detection signal of a crank angle sensor 55 that detects a rotation angle of a crankshaft (not shown) of the internal combustion engine 10, and an ignition plug is based on this rotation angle detection signal. It has a function of discriminating cylinders 11, 12, 13 or 14 that are in the compression stroke at the time of discharge of 21 and 24 or at the time of discharge of the spark plugs 22 and 23 (cylinder discrimination means). Based on the output waveform of the secondary voltage signal, the discharge gap 21a, 22a, 23a or 24a of the spark plug 21, 22, 23 or 24 assembled in the determined cylinder 11, 12, 13 or 14 is detected ( It also has a function of determining whether or not it is good (gap detection means).
[0033]
At the time of inspection of the ignition system, an electric motor 54 as a rotating means is connected to the crankshaft of the internal combustion engine 10. The motor 54 is rotationally controlled by the ECU 36 and rotationally drives the crankshaft.
[0034]
At the time of inspection of the ignition system, the ECU 36 rotates the internal combustion engine 10 (crankshaft) by the motor 54, and based on the rotation angle detection signal of the crank angle sensor 55 (according to the rotation angle of the crankshaft), Thus, by controlling the base currents of the transistors 34 and 35 to perform on / off control of the transistors 34 and 35, the energization from the battery 33 to the primary coils 31B and 32B of the ignition coils 31 and 32 is controlled. The timing at which the secondary voltage induced in the secondary coils 31A, 32A of the coils 31, 32 is applied to the spark plugs 21, 22, 23, 24 to discharge the spark plugs 21, 24 simultaneously, and the spark plugs 22, 23 are Control the timing of discharging at the same time.
[0035]
That is, the ECU 36 functions as a discharge control means also during the ignition system inspection, and rotates the internal combustion engine 10 (crankshaft) by the motor 54, that is, performs a so-called motoring operation performed in a fuel cut state. The spark plugs 21, 24 or 22, 23 of the two cylinders 11, 14 or 12, 13 are simultaneously discharged.
[0036]
Specifically, as shown in FIG. 3, for the cylinders 11 and 14, first, when the pressure in the combustion chamber of the first cylinder 11 becomes high due to the compression stroke, the first spark plug 21 of the first cylinder 11. At the same time, the fourth spark plug 24 of the fourth cylinder 14 whose pressure in the combustion chamber has become low during the exhaust stroke is also discharged. Next, when the combustion chamber of the fourth cylinder 14 becomes high pressure due to the compression stroke, the fourth spark plug 24 of the fourth cylinder 14 is discharged, and at the same time, the first cylinder 11 whose pressure inside the combustion chamber becomes low pressure during the exhaust stroke. The first spark plug 21 is also discharged.
[0037]
For the cylinders 12 and 13, first, when the combustion chamber of the third cylinder 13 becomes high pressure due to the compression stroke, the third spark plug 23 of the third cylinder 13 is discharged, and at the same time, the combustion chamber is low pressure during the exhaust stroke. The second spark plug 22 of the second cylinder 12 that has become is also discharged. Next, when the combustion chamber of the second cylinder 12 becomes high pressure due to the compression stroke, the second ignition plug 22 of the second cylinder 12 is discharged, and at the same time, the third cylinder 13 whose pressure inside the combustion chamber becomes low pressure during the exhaust stroke. The third spark plug 23 is also discharged.
[0038]
In the first detection coil 51, the change in the magnetic field induced by the discharge of the spark plugs 21 and 24 at this time, that is, the discharge on the secondary side (secondary coil 31A side) of the first ignition coil 31 is expressed as a voltage. This voltage is output to the inspection unit 53 as a secondary voltage signal of the first ignition coil 31, and the second detection coil 52 discharges the spark plugs 22 and 23 at this time, that is, The change of the magnetic field induced by the discharge on the secondary side (secondary coil 32A side) of the second ignition coil 32 is converted into the change of voltage, and this voltage is inspected as a signal of the secondary voltage of the second ignition coil 32. Output to unit 53.
[0039]
In the inspection unit 53, the secondary voltage signal output from the detection coils 51 and 52 is input and displayed. FIG. 3 illustrates the waveform of the secondary voltage signal displayed in the inspection unit 53. For example, when a current flows through the primary and secondary coils 31A and 31B in the first ignition coil 31, magnetic fields corresponding to the primary and secondary currents are generated. At this time, if the primary current is constant, the secondary current is also constant. Therefore, the discharge time T is the size of the discharge gap 21a, 22a, 23a or 24a of the spark plug 21, 22, 23 or 24 ( It depends on the magnitude of the dielectric breakdown voltage proportional to the area.
[0040]
Further, the magnitude of the back electromotive force generated at the moment when the discharge of the secondary current is finished depends on the amount of change in the magnetic field at this time, and therefore, the magnitude of the discharge gap 21a, 22a, 23a or 24a. Proportional. Therefore, the amount of change in the back electromotive force at this time can be observed as the amplitude H of the secondary voltage signal, and the magnitude of the amplitude H is proportional to the size of the discharge gap 21a, 22a, 23a or 24a.
[0041]
FIG. 5 shows an example of a preferable chart that can be used to determine whether the discharge gap is good or bad. The chart of FIG. 5 shows the discharge time T obtained from the output waveform of the secondary voltage signal in the inspection unit 53 and the amplitude H at the end of the discharge, and the discharge gaps 21a, 22a, 23a or 24a in the spark plugs 21, 22, 23 or 24. Therefore, the pass / fail judgment criteria are defined. Specifically, the smaller the discharge gap 21a, 22a, 23a, or 24a in the spark plug 21, 22, 23, or 24, the longer the discharge time T and the smaller the amplitude H of the output waveform that accompanies the change in counter electromotive force. Conversely, as the discharge gap 21a, 22a, 23a or 24a is larger, the discharge time T is shorter and the amplitude H tends to increase. From this, for example, if the normal discharge time To and the normal amplitude Ho when the discharge gap 21a, 22a, 23a or 24a of the spark plug 21, 22, 23 or 24 is a normal size are measured in advance, Based on these normal discharge time To and normal amplitude Ho, the normal point Po can be defined in the chart of FIG.
[0042]
For example, when the discharge time T obtained at the time of inspection of the ignition system is shorter than the normal discharge time To and the amplitude H is larger than the normal amplitude Ho, the spark plug 21, 22, 23 or 24 to be inspected It is considered that the discharge gap 21a, 22a, 23a or 24a is larger than the normal value. On the other hand, when the discharge time T obtained at the time of inspection of the ignition system is longer than the normal discharge time To and the amplitude H is smaller than the normal amplitude Ho, the discharge gap of the spark plug 21, 22, 23 or 24 to be inspected 21a, 22a, 23a or 24a is considered to be smaller than the normal value.
[0043]
For example, the inspection unit 53 can include a comparison circuit. In this comparison circuit, the values of the discharge time T and the amplitude H obtained during the inspection of the ignition system are set to the normal discharge time To and the normal amplitude Ho, respectively. Make a comparison. As a result, if there is no particular magnitude relative to the regular value, the inspection unit 53 determines that the discharge gap 21a, 22a, 23a or 24a of the spark plug 21, 22, 23 or 24 is appropriate (non-defective product). it can. On the other hand, when it is recognized that the size is extremely large compared to the normal value, the inspection unit 53 determines that the discharge gap 21a, 22a, 23a or 24a of the spark plug 21, 22, 23 or 24 is defective. can do.
[0044]
More preferably, constant allowable ranges to and ho can be given to the values of the normal discharge time To and the normal amplitude Ho in the chart of FIG. 5, respectively, and the values of the discharge time T and the amplitude H obtained when the ignition system is inspected. Are included in the allowable ranges to and ho (hatched portions in the figure), the discharge gap 21a, 22a, 23a or 24a of the spark plug 21, 22, 23 or 24 is properly set in the inspection unit 53. It can also be determined.
[0045]
In the present embodiment, by using the detection coils 51 and 52 for detecting the magnetic field, the change in the magnetic field induced by the discharge on the secondary side of the ignition coils 31 and 32 is captured and the two coils of the ignition coils 31 and 32 are detected. In order to detect the secondary voltage signal, the secondary voltage signal can be detected without contact with the ignition coils 31 and 32, and the internal combustion engine 10 is provided with components of the ignition system such as the ignition coils 31 and 32. In a state in which all of these are incorporated, the discharge gaps 21a, 22a, 23a, and 24a of the spark plugs 21, 22, 23, and 24 can be detected (good / bad judgment) based on the discharge by the actual ignition system. Therefore, the determination result can be applied to the product inspection in the manufacturing process of the internal combustion engine 10 as it is. On the other hand, when the spark plug is inspected using the discharge voltage applying device as in the above-mentioned Patent Document 1, since the inspection including the ignition coil to be actually used cannot be performed, the ignition coil inspection process is separately performed. Need. In the above-mentioned Patent Document 2, a special probe including a voltage divider must be connected to the secondary coil of the ignition coil to detect the secondary voltage signal.
[0046]
As described above, the secondary voltage signal of the ignition coil is detected using the detection coil for detecting the magnetic field, and the discharge time T and the amplitude H are obtained from the output waveform of the secondary voltage signal, so that the discharge gap of the spark plug is obtained. It is the same as that of the above-mentioned device of Patent Document 3 previously proposed by the present inventors.
[0047]
In the present embodiment, by synchronizing the rotation of the internal combustion engine 10 with this, one spark plug in the same set is discharged under high pressure, and the other spark plug is discharged under low pressure, so that the semi-direct Even with the ignition method, the discharge gap of the spark plug can be reliably detected. In other words, in the present embodiment, the discharge gap of any one of the spark plugs (spark plugs 21 and 24 or spark plugs 22 and 23) of the same group that forms a closed loop and is simultaneously discharged is the same. Even when it is smaller, it is possible to find a defective spark plug.
[0048]
More specifically, the ignition system of the internal combustion engine 10 to be inspected in the present embodiment is a semi-direct ignition system, and two spark plugs are electrically connected in series to form a closed loop. Therefore, it is difficult to detect a defective spark plug with a small discharge gap by simply discharging two spark plugs simultaneously under the same pressure condition.
[0049]
For example, of the same set of spark plugs 21 and 24 electrically connected in series, the first spark plug 21 has a discharge gap 21a of a normal size (for example, about 1.1 mm), while the fourth spark plug 24 If the discharge gap 24a is crushed and becomes abnormally small (for example, about 0.2 mm) due to contact of the electrode part when assembled in the internal combustion engine 10, the discharge is directed to the first spark plug 21 having a larger discharge gap. Therefore, it is difficult to detect a failure of the fourth spark plug 24 simply by simultaneously discharging the spark plugs 21 and 24 under the same pressure condition.
[0050]
Therefore, in the present embodiment, as described above, the internal combustion engine (crankshaft) 10 is rotated by the motor 54, and the two cylinders 11, 14 spark plugs 21, 24 of the same set are simultaneously discharged. As a result, when the first spark plug 21 is discharged under high pressure due to the compression stroke, the fourth spark plug 24 is simultaneously discharged under low pressure due to the exhaust stroke, and the fourth spark plug 24 is discharged under high pressure due to the compression stroke. At this time, since the first spark plug 21 is discharged under a low pressure due to the exhaust stroke, it is easy to determine whether the spark plugs 21 and 24 are good or bad.
[0051]
This will be further described with reference to Tables 1 to 3. In Tables 1 to 3, “single discharge time” is assumed that only the first spark plug 21 or only the fourth spark plug 24 is connected to the secondary coil 31A of the first ignition coil 31. Discharge time (discharge time obtained from the output waveform of the secondary voltage signal by the first detection coil 51). The “synthetic discharge time” is the discharge when the first ignition plug 21 and the fourth ignition plug 24 are connected in series to the secondary coil 31A of the first ignition coil 31 to form a closed loop as shown in FIG. Time (discharge time obtained from the output waveform of the secondary voltage signal by the first detection coil 51). “Short” means that the single discharge time and the combined discharge time are relatively short, “Long” means that the single discharge time and the combined discharge time are relatively long, and “Medium” means the single discharge time. It means that the discharge time and the combined discharge time are between “short” and “long”.
[0052]
In discharging, it is known that when the pressure is increased, the dielectric breakdown voltage is increased and the discharge time is shortened (Baschen's law). Therefore, for example, assuming that only the spark plug 21 is connected to the secondary coil 31A of the first ignition coil 31, if the spark plug 21 is discharged while the internal combustion engine 10 is rotated by the motor 54, the spark plug 21 The single discharge time is as shown in Table 1.
[0053]
[Table 1]

[0054]
That is, if the size of the discharge gap 21a of the spark plug 21 is normal, the combustion chamber of the cylinder 11 has a high pressure in the compression stroke, so that the single discharge time is “short”, and the combustion chamber of the cylinder 11 in the exhaust stroke Since the pressure is low, the single discharge time is “medium”. On the other hand, if the discharge gap 21a of the spark plug 21 is small, the combustion chamber of the cylinder 11 has a high pressure in the compression stroke, so that the single discharge time becomes “medium”, and the combustion chamber of the cylinder 11 has a low pressure in the exhaust stroke. The single discharge time becomes “long”. In both the compression stroke and the exhaust stroke, the single discharge time is shorter when the discharge gap 21a is smaller than when it is normal.
[0055]
However, for example, when the discharge gap 21a of the first spark plug 21 of the first cylinder 11 is a normal size and the discharge gap 24a of the fourth spark plug 24 of the fourth cylinder 14 is small, the spark plugs 21 and 24 are connected. When discharge is performed simultaneously under the same pressure conditions (for example, the combustion chambers of the cylinders 11 and 14 are in the same atmospheric pressure), the first spark plug 21 is “medium” and the fourth spark plug 24 is at the single discharge time as shown in Table 2. Is “long”, but the combined discharge time is “medium”.
[0056]
[Table 2]

[0057]
That is, the first spark plug 21 having the regular (large) discharge gap 21a has a shorter single discharge time than the fourth spark plug 24 having the smaller discharge gap 24a. The spark plug 21 is dominant, and the influence of the reduced discharge gap 24a of the fourth spark plug 24 does not appear in the combined discharge time. That is, there is no difference in the combined discharge time in both spark plugs 21 and 24 as compared with the case where the discharge gaps 21a and 24a are regular sizes. In this case, the secondary voltage generated by the first detection coil 51 is not different. Even if the discharge time T and the amplitude H are obtained from the output waveform of the signal, it cannot be detected that the discharge gap 24a of the fourth spark plug 24 is small.
[0058]
Therefore, in the present embodiment, the spark plugs 21 and 24 are simultaneously discharged while the internal combustion engine 10 is rotated by the motor 54 as described above (see FIG. 3). In this case, for example, when the discharge gap 21a of the first spark plug 21 of the first cylinder 11 is a normal size and the discharge gap 24a of the fourth spark plug 24 of the fourth cylinder 14 is small, Table 3 The discharge time as shown in FIG.
[0059]
[Table 3]

[0060]
That is, when the first spark plug 21 is discharged in the compression stroke (under high pressure), the fourth spark plug 24 is simultaneously discharged in the exhaust stroke (under low pressure). At this time, the discharge gap 21a of a normal size is formed. The single spark discharge time of the first spark plug 21 having “short” and the single discharge time of the fourth spark plug 24 having the small discharge gap 24a is “long”, and therefore the first spark plug 21 having a large discharge gap is better. It becomes dominant and the synthetic discharge time becomes “short”. That is, the waveform of the secondary voltage signal of the first ignition coil 31 during this discharge reflects the size of the discharge gap 21a of the first spark plug 21.
[0061]
Subsequently, when the fourth spark plug 24 is discharged in the compression stroke (under high pressure), the first spark plug 21 is simultaneously discharged in the exhaust stroke (under low pressure). At this time, the single discharge time of the first spark plug 21 having the regular discharge gap 21a is “medium”, and the single discharge time of the fourth spark plug 24 having the small discharge gap 24a is also “medium”. The synthetic discharge time is also “medium”. That is, when the fourth spark plug 24 is discharged in the compression stroke, there is a difference in discharge time from that in the exhaust stroke, and the waveform of the secondary voltage signal of the first ignition coil 31 at the time of discharge is This reflects the size of the discharge gap 24 a of the four spark plugs 24.
[0062]
Similarly, when the discharge gap 24a of the fourth spark plug 24 is a normal size and the discharge gap 21a of the first spark plug 21 is small, the first spark plug 21 is exhausted (under low pressure). There is a difference between the combined discharge time (short) when discharged and the combined discharge time (middle) when discharged during the compression stroke (under high pressure), and the former combined discharge time (the first ignition coil 31 two times). The waveform of the secondary voltage signal) reflects the size of the discharge gap 24a of the fourth spark plug 24, but the latter combined discharge time (the waveform of the secondary voltage signal of the first ignition coil 31) is the first spark plug. This reflects the size of the 21 discharge gaps 21a.
[0063]
Although the detailed description is omitted, the second spark plug is also obtained by simultaneously discharging the spark plugs 22 and 23 while rotating the internal combustion engine 10 with the motor 54 for the other same spark plugs 22 and 23. When the discharge gap 22a of the second spark plug 23 is small and the discharge gap 23a of the third spark plug 23 is small, or when the discharge gap 23a of the third spark plug 23 is normal and the discharge gap 23a of the third spark plug 23 is small. Even when the gap 22a is small, the same applies to the spark plugs 21 and 24. That is, the combined discharge when the third spark plug 23 with a small discharge gap or the second spark plug 22 with a small discharge gap discharges in the exhaust stroke (under low pressure) and in the compression stroke (under high pressure). There is a difference in time, and the former combined discharge time (the waveform of the secondary voltage signal of the second ignition coil 32) is the size of the discharge gap 22a of the larger second spark plug 22 or the larger third time. This reflects the size of the discharge gap 23a of the spark plug 23, but the latter combined discharge time (the waveform of the secondary voltage signal of the second ignition coil 32) has a smaller discharge gap 23a of the third spark plug 23. Or the size of the discharge gap 22a of the smaller second spark plug 22 is reflected.
[0064]
Therefore, in the inspection unit 53, the rotation angle detection signal of the crank angle sensor 55 is input as described above, and when the spark plugs 21 and 24 are discharged or when the ignition plugs 22 and 23 are discharged based on the rotation angle detection signal. The cylinder 11, 12, 13 or 14 in the compression stroke is determined, and the spark plug 21, 22, 23 or 24 assembled to the cylinder 11, 12, 13 or 14 determined to be in the compression stroke by this determination function. The discharge gap 21a, 22a, 23a or 24a is detected based on the output waveform of the secondary voltage signal of the first ignition coil 31 or the second ignition coil 32 detected by the detection coil 51 or 51 at this time. That is, the discharge time T and the amplitude H (only one of them) may be obtained from the output waveform, and the quality of the discharge gaps 21a, 22a, 23a, 24a of the spark plugs 21, 22, 23, 24 is determined.
[0065]
Therefore, according to the present embodiment, the discharge gap 21a of the spark plugs 21, 22, 23, 24 of each cylinder 11, 12, 13, 14 is also applied to the internal combustion engine 10 having a semi-direct ignition type ignition system. , 22a, 23a, 24a can be reliably detected. Moreover, it is possible to guarantee (inspect) not only the spark plug but also the entire ignition system including the ignition coil and the like. As a result of actually inspecting an internal combustion engine having an ignition system of a semi-direct ignition system using the apparatus of the present invention, for example, the discharge gap of one of the two spark plugs of the same set is normally large. When the discharge gap of the other spark plug plug is 0.3 mm or less (1.1 mm), it is confirmed that the defective spark plug can be detected almost 100%. Of course, detection is possible even if it is 0.3 mm or more.
[0066]
In the above description, the case of inspecting a four-cylinder semi-direct ignition internal combustion engine has been described. However, the present invention is not limited to this. It can also be applied when inspecting institutions.
[0067]
In the above description, the internal combustion engine 10 (crankshaft) is rotated by the motor 54 (motoring operation). However, the present invention is not necessarily limited to this, so-called firing that actually supplies fuel to each cylinder and ignites it. The internal combustion engine 10 may be rotated by operation. However, in the motoring operation, the state of the airflow in the combustion chambers of the cylinders 11, 12, 13, and 14 is more stable and the discharge state is more stable than in the firing operation. , 22, 23, 24 can be detected.
[0068]
In the above description, the case where one of the discharge gaps of the two spark plugs of the same set is normal and the other is small has been described. However, the present invention is not necessarily limited to this, and in the present invention, for example, the discharge gaps of the two spark plugs The discharge gap can be detected even when one of the two is regular and the other is large.
[0069]
【The invention's effect】
As described above in detail with the embodiment of the invention, according to the ignition plug gap detection method for an internal combustion engine of the first invention, a plurality of cylinders are divided into a plurality of groups each of which is divided into two groups. An ignition plug gap detection method for an internal combustion engine having a semi-direct ignition system in which an ignition plug of a cylinder is electrically connected to a secondary side of the same ignition coil and simultaneously discharged, and the internal combustion engine is rotated. The ignition plugs of the two cylinders of the same set are simultaneously discharged while detecting and monitoring the waveform of the secondary voltage signal of the ignition coil at the time of discharge, and the cylinders in the compression stroke at the time of discharge are discriminated. Then, the discharge gap of the spark plug assembled in the cylinder determined to be in the compression stroke is detected based on the waveform of the secondary voltage signal. The order, wherein, even for an internal combustion engine having an ignition system of the semi-direct ignition system, the discharge gap of the spark plug of each cylinder can be reliably detected. For example, even when one of the discharge gaps of two spark plugs of the same set is a regular size and the other is small, the discharge gap of the small spark plug can be reliably detected.
[0070]
Further, according to the ignition plug gap detection method for an internal combustion engine of the second invention, in the ignition plug gap detection method for the internal combustion engine of the first invention, the internal combustion engine is rotated by a motor. Compared to the above, since the state of the airflow in the combustion chamber of the cylinder is stabilized and the discharge state is also stabilized, the discharge gap of the spark plug can be detected more reliably.
[0071]
Further, according to the ignition plug gap detection method for an internal combustion engine of the third invention, in the ignition plug gap detection method for the internal combustion engine of the first or second invention, the secondary voltage signal is provided in the vicinity of the ignition coil. The secondary voltage signal can be detected in an electrically non-contact manner with respect to the ignition coil because the detection coil is detected and monitored, and the internal combustion engine has an ignition system configuration such as an ignition coil. In a state where all the parts are incorporated, the discharge gap of the spark plug can be detected based on the discharge by the actual ignition system. Therefore, it is possible to guarantee (inspect) not only the ignition plug but also the entire ignition system including the ignition coil.
[0072]
Further, according to the ignition plug gap detecting device for an internal combustion engine of the fourth invention, a plurality of cylinders are divided into a plurality of groups each including two cylinders, and the ignition plugs of two cylinders of the same group are arranged on the secondary side of the same ignition coil. An ignition plug gap detection device for an internal combustion engine having an ignition system of a semi-direct ignition system that is electrically connected and discharged at the same time, comprising: a rotating means for rotating the internal combustion engine; and the rotating means for rotating the internal combustion engine. The discharge control means for simultaneously discharging the ignition plugs of the two cylinders of the same set, the secondary voltage signal detection means for detecting the secondary voltage signal of the ignition coil during the discharge, and the secondary voltage signal detection means Waveform monitoring means for monitoring the waveform of the secondary voltage signal detected by the cylinder, cylinder discrimination means for discriminating a cylinder in the compression stroke at the time of discharge Gap detection means for detecting a discharge gap of a spark plug assembled to a cylinder determined to be in the compression stroke by the cylinder determination means based on the waveform of the secondary voltage signal. Therefore, the discharge gap of the spark plug of each cylinder can be reliably detected even for an internal combustion engine having a semi-direct ignition type ignition system. For example, even when one of the discharge gaps of two spark plugs of the same set is a regular size and the other is small, the discharge gap of the small spark plug can be reliably detected.
[0073]
Further, according to the spark plug gap detecting device for an internal combustion engine of the fifth invention, in the spark plug gap detecting device for the internal combustion engine of the fourth invention, the rotating means is a motor. In comparison, since the state of the airflow in the combustion chamber of the cylinder is stabilized and the discharge state is also stabilized, the discharge gap of the spark plug can be detected more reliably.
[0074]
According to the ignition plug gap detecting device for an internal combustion engine of the sixth invention, in the ignition plug gap detecting device for the internal combustion engine of the fourth or fifth invention, the secondary voltage signal detecting means is provided in the vicinity of the ignition coil. The detection coil detects the secondary voltage signal by detecting a change in the magnetic field due to the secondary discharge of the ignition coil, and is electrically connected to the ignition coil. The secondary voltage signal can be detected in a non-contact manner, and all the ignition system components such as the ignition coil are incorporated in the internal combustion engine, and the discharge gap of the ignition plug is determined based on the discharge by the actual ignition system. Detection is possible. Therefore, it is possible to guarantee (inspect) not only the ignition plug but also the entire ignition system including the ignition coil.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a state at the time of inspection by an ignition plug gap detection device for an internal combustion engine according to an embodiment of the present invention.
FIG. 2 is a diagram showing an example of arrangement of detection coils.
FIG. 3 is a chart showing the discharge timing of a spark plug assembled to each cylinder of the internal combustion engine.
FIG. 4 is a graph showing an output waveform of a secondary voltage signal.
FIG. 5 is a chart for determining whether a discharge gap is good or bad.
FIG. 6 is a configuration diagram of a direct ignition type ignition system.
[Explanation of symbols]
10 Internal combustion engine
11, 12, 13, 14 1st to 4th cylinder
21, 22, 23, 24 1st to 4th spark plugs
21a, 22a, 23a, 24a Discharge gap
31, 32 First and second ignition coils
31A, 32A Secondary coil
31B, 32B primary coil
31C, 32C ferrite core
33 battery
34, 35 first and second transistors
36 ECU
51, 52 First and second detection coils
53 Inspection unit
54 Motor
55 Crank angle sensor

Claims (6)

Equipped with a semi-direct ignition system that divides a plurality of cylinders into two groups, and electrically connects the spark plugs of the two cylinders of the same group to the secondary side of the same ignition coil for simultaneous discharge An ignition plug gap detection method for an internal combustion engine, wherein the ignition plugs of the two cylinders of the same set are simultaneously discharged while rotating the internal combustion engine, and a waveform of a secondary voltage signal of the ignition coil at the time of discharge is obtained. A cylinder that is detected and monitored and that is in a compression stroke at the time of discharge is discriminated, and a discharge gap of a spark plug that is assembled to the cylinder that is discriminated to be in the compression stroke is determined by the waveform of the secondary voltage signal. And a spark plug gap detection method for an internal combustion engine. 2. The ignition plug gap detection method for an internal combustion engine according to claim 1, wherein the internal combustion engine is rotated by a motor. The ignition plug gap detection method for an internal combustion engine according to claim 1 or 2, wherein the secondary voltage signal is detected and monitored by a detection coil provided in the vicinity of the ignition coil. Spark plug gap detection method. Equipped with a semi-direct ignition system that divides a plurality of cylinders into two groups, and electrically connects the spark plugs of the two cylinders of the same group to the secondary side of the same ignition coil for simultaneous discharge An ignition plug gap detecting device for an internal combustion engine, comprising: a rotating means for rotating the internal combustion engine; and a discharge control means for simultaneously discharging the ignition plugs of the two cylinders of the same set while rotating the internal combustion engine by the rotating means. And secondary voltage signal detection means for detecting a secondary voltage signal of the ignition coil at the time of discharge, and waveform monitoring means for monitoring the waveform of the secondary voltage signal detected by the secondary voltage signal detection means, The cylinder discriminating means for discriminating the cylinder in the compression stroke at the time of discharge, and the cylinder discriminated to be in the compression stroke by the cylinder discrimination means Is a discharge gap of the spark plug has the spark plug gap detecting device for an internal combustion engine, characterized in that a gap detection means for detecting on the basis of the waveform of the secondary voltage signal. 5. The spark plug gap detecting device for an internal combustion engine according to claim 4, wherein the rotating means is a motor. 6. The ignition plug gap detection device for an internal combustion engine according to claim 4 or 5, wherein the secondary voltage signal detection means is a detection coil provided in the vicinity of the ignition coil. An ignition plug gap detecting device for an internal combustion engine, wherein the secondary voltage signal is detected by detecting a change in a magnetic field due to a discharge on the secondary side.

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