JPH04134180A - Spark plug for detecting ion current - Google Patents
Spark plug for detecting ion currentInfo
- Publication number
- JPH04134180A JPH04134180A JP25513790A JP25513790A JPH04134180A JP H04134180 A JPH04134180 A JP H04134180A JP 25513790 A JP25513790 A JP 25513790A JP 25513790 A JP25513790 A JP 25513790A JP H04134180 A JPH04134180 A JP H04134180A
- Authority
- JP
- Japan
- Prior art keywords
- electrode
- discharge electrode
- discharge
- spark plug
- ion current
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000001514 detection method Methods 0.000 claims abstract description 17
- 238000002485 combustion reaction Methods 0.000 abstract description 23
- 150000002500 ions Chemical class 0.000 abstract description 23
- 150000001768 cations Chemical class 0.000 abstract description 12
- 238000004880 explosion Methods 0.000 abstract description 12
- 230000035945 sensitivity Effects 0.000 abstract description 9
- 210000004907 gland Anatomy 0.000 abstract description 5
- 238000002844 melting Methods 0.000 abstract description 4
- 230000008018 melting Effects 0.000 abstract description 4
- 238000000034 method Methods 0.000 abstract 1
- 238000004804 winding Methods 0.000 description 7
- 239000000446 fuel Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000005856 abnormality Effects 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
Landscapes
- Ignition Installations For Internal Combustion Engines (AREA)
Abstract
Description
【発明の詳細な説明】
[産業上の利用分野]
この発明は、爆発行程時に燃焼室内に発生する、イオン
電流を検出する点火プラグに関し、特に検出感度を向上
させたイオン電流検出用点火プラグに関するものである
。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a spark plug for detecting ionic current generated in a combustion chamber during an explosion stroke, and particularly to a spark plug for detecting ionic current with improved detection sensitivity. It is something.
[従来の技術]
一般に、自動車エンジン等に用いられる内燃機関におい
ては、クランク軸と同期駆動される複数の気筒(例えば
、4気筒)により、ECU(マイクロコンピュータ)の
制御下で、燃料(混合気)の吸入、圧縮、爆発(点火)
及び排気の4サイクルが繰り返し行われている。このと
き、ピストンで圧縮された燃料が点火サイクルにおいて
最適且つ確実に燃焼されないと、他の気筒に対して異常
な負荷がかかり、エンジンが損傷したり、未然ガス流出
により種々の障害をもたらすおそれがある。従って、内
燃機関の安全を確保するためには、各気筒について確実
に燃焼が行われたか否かを常に検出する必要がある。[Prior Art] Generally, in an internal combustion engine used in an automobile engine, a plurality of cylinders (for example, 4 cylinders) are driven in synchronization with a crankshaft, and fuel (air-fuel mixture) is controlled under the control of an ECU (microcomputer). ) inhalation, compression, explosion (ignition)
Four cycles of exhaustion and evacuation are repeated. At this time, if the fuel compressed by the piston is not combusted optimally and reliably during the ignition cycle, an abnormal load will be placed on other cylinders, which may damage the engine or cause various problems due to gas leakage. be. Therefore, in order to ensure the safety of the internal combustion engine, it is necessary to constantly detect whether combustion has occurred reliably in each cylinder.
このため、従来より、爆発サイクルにおいて点火プラグ
のギャップ間に発生するイオン電流を検出し、イオン電
流レベルに基づいて燃焼状態を判定する装置が提案され
ている。更に、イオン電流の検出機能を点火プラグに設
けることにより、小形化を実現した装置も提案されてい
る。For this reason, devices have been proposed that detect the ion current generated between the spark plug gaps during the explosion cycle and determine the combustion state based on the ion current level. Furthermore, a device has been proposed that is made smaller by providing an ion current detection function in the spark plug.
第3図は一般的なイオン電流検出装置を示す回路図であ
る。FIG. 3 is a circuit diagram showing a general ion current detection device.
図において、(1〉は負の高電圧を発生する高圧電源、
(2)は各一端が高圧電源(1)に接続された一次巻線
(2a)及び二次巻線(2b)を有する点火コイル、(
3)は−次巻線(2a)とグランド間に挿入されたパワ
ートランジスタ、(4)は二次巻線(2b)にカソード
が接続された逆流防止用のダイオードである。In the figure, (1> is a high voltage power supply that generates a negative high voltage;
(2) is an ignition coil having a primary winding (2a) and a secondary winding (2b) connected at one end to the high voltage power supply (1);
3) is a power transistor inserted between the negative winding (2a) and the ground, and (4) is a backflow prevention diode whose cathode is connected to the secondary winding (2b).
(5)はダイオード(4)を介して二次巻線(2b)に
接続された点火プラグであり、ダイオード(4)のアノ
ードに接続された放電用電極(5a)と、放電用電極(
5a)に対向配置されたグランド電極(5b)とを備え
ている。尚、グランド電極(5b)は、点火プラグ(5
)のハウジング即ち燃焼室壁(図示せず)に接続されて
おり、放電用電極(5a)及びグランド電極(5b)は
、各気筒の燃焼室内に露出されている。、(6)はダイ
オード(4)のアノードに接続されてイオン電流工を検
出するための数100v程度の電源、(7)はダイオー
ド(4)及び点火プラグ(5a)の接続点と電源(6)
との間に挿入された逆流防止用のダイオード、(8)は
電源(6)とグランドとの間に挿入された抵抗器、(9
)は電源(6)及び抵抗器(8)の接続点に設けられた
イオン電流検出用の出力端子である。(5) is a spark plug connected to the secondary winding (2b) via the diode (4), and has a discharge electrode (5a) connected to the anode of the diode (4), and a discharge electrode (5a) connected to the anode of the diode (4).
5a) and a ground electrode (5b) disposed opposite to the ground electrode (5b). In addition, the ground electrode (5b) is connected to the spark plug (5b).
), and the discharge electrode (5a) and ground electrode (5b) are exposed inside the combustion chamber of each cylinder. , (6) is a power source of several hundred volts connected to the anode of the diode (4) to detect the ion current, and (7) is the connection point between the diode (4) and the spark plug (5a) and the power source (6). )
(8) is the resistor inserted between the power supply (6) and the ground, (9) is the resistor inserted between the power supply (6) and the ground.
) is an output terminal for detecting ion current provided at the connection point of the power supply (6) and the resistor (8).
次に、第3図に示したイオン電流検出装置の動作につい
て説明する。Next, the operation of the ion current detection device shown in FIG. 3 will be explained.
点火サイクルにおいて、ECU(図示せず)によりパワ
ートランジスタ(3)がオンオフ制御され、−次巻線(
2a)の通電遮断が行われると、二次巻線(2b)に所
定の高電圧が誘起される。これにより、点火プラグ(5
)のグランド電極(5b)がち放電用電極(5a)に向
けて放電火花が生じ、燃焼室内の燃料は爆発する。In the ignition cycle, the power transistor (3) is controlled on and off by the ECU (not shown), and the - next winding (
When energization 2a) is interrupted, a predetermined high voltage is induced in the secondary winding (2b). As a result, the spark plug (5
), a discharge spark is generated toward the discharge electrode (5a), and the fuel in the combustion chamber explodes.
このとき、正常に爆発が行われると、燃焼室内に大量の
陽イオンが発生し、この陽イオンは、イオン電流工とな
って放電用電極(5a)からダイオード(7)を介して
電源(6)に流れ込み、更に、抵抗器(8)を介してグ
ランドに流れ込む。従って、抵抗器(8)で生じる電圧
降下量を検出すれば、イオン電流Iのレベルを知ること
ができ、正常に燃焼が行われたが否かを判定することが
できる。At this time, if the explosion occurs normally, a large amount of cations will be generated in the combustion chamber, and these cations will become an ion current and flow from the discharge electrode (5a) to the power source (6) via the diode (7). ) and further flows to ground via the resistor (8). Therefore, by detecting the amount of voltage drop occurring across the resistor (8), it is possible to know the level of the ion current I, and it is possible to determine whether or not combustion has occurred normally.
イオン電流Iのレベルは出力端子(9)がらECUに出
力され、ECUは、点火制御された気筒において正常に
燃焼が行われた否かを判定する。そして、失火等の異常
が判定された場合には、点火タイミングをフィードバッ
ク調整したり、危険防止のために体筒させるなどの処理
を行う。The level of the ion current I is output from the output terminal (9) to the ECU, and the ECU determines whether or not combustion has occurred normally in the ignition-controlled cylinder. If an abnormality such as a misfire is determined, the ignition timing is feedback-adjusted or the engine is turned on to prevent danger.
ところで、従来の点火プラグ(5)は、第4図のように
構成されており、中心電極となる放電用電極(5a)を
側面から覆うようにグランド電極(5b)が設けられて
いる。By the way, the conventional spark plug (5) is configured as shown in FIG. 4, and a ground electrode (5b) is provided so as to cover the discharge electrode (5a), which serves as the center electrode, from the side.
このとき、放電用電極(5a)の突出量が短いので、爆
発時に発生した陽イオンは、放電用電極(5a)に対し
て十分に流れ込むことができない。又、放電用電極(5
a)及びグランド電極(5b)間に存在する陽イオンは
確実に放電用電極(5a)に流れ込むことができるが、
グランド電極(5b)の外側の燃焼室内に存在する陽イ
オンは、グランド電極(5b)が障害となって放電用電
極(5a)に流れ込むことができない。At this time, since the amount of protrusion of the discharge electrode (5a) is short, cations generated during the explosion cannot sufficiently flow into the discharge electrode (5a). In addition, a discharge electrode (5
Although the cations existing between a) and the ground electrode (5b) can surely flow into the discharge electrode (5a),
The cations existing in the combustion chamber outside the ground electrode (5b) cannot flow into the discharge electrode (5a) because the ground electrode (5b) becomes an obstacle.
従って、出力端子(9)におけるイオン電流Iのレベル
が十分に得られず、検出感度を向上させることはできな
い。Therefore, a sufficient level of ion current I at the output terminal (9) cannot be obtained, and detection sensitivity cannot be improved.
一方、第5図のように、放電用電極(5a)の突出量を
長くすれば、放電用電極(5a)とグランド電極(5b
)との間で多くの空間電流が生じるので、イオン電流I
の検出感度が高くなることは、実験的に知られている。On the other hand, as shown in FIG. 5, if the amount of protrusion of the discharge electrode (5a) is increased, the discharge electrode (5a) and the ground electrode (5b)
), so the ionic current I
It is experimentally known that the detection sensitivity of
又、点火プラグ(5)のハウジング即ち燃焼室壁がグラ
ンド電位であることがら、第5図の構成は、放電用電極
(5a)と燃焼室壁との間の空間電流も増大させるので
、検出感度の向上に対して有効である。Furthermore, since the housing of the spark plug (5), that is, the wall of the combustion chamber, is at ground potential, the configuration shown in FIG. 5 also increases the space current between the discharge electrode (5a) and the wall of the combustion chamber. This is effective for improving sensitivity.
しかし、この場合、グランド電極(5b)が放電用電極
(5a)を覆うように更に突出していするため、グラン
ド電極(5b)の外側の燃焼室内に存在する陽イオンは
、前述と同様に放電用電極に流れ込むことができない。However, in this case, since the ground electrode (5b) further protrudes so as to cover the discharge electrode (5a), the cations existing in the combustion chamber outside the ground electrode (5b) are absorbed by the discharge electrode as described above. cannot flow into the electrode.
又、放電用電極(5a)又はグランド電極(5b)が燃
焼室内に多く突出することは、爆発時の高温雰囲気によ
り熔融するおそれがあり、熱的にも不利になってしまう
。Further, if the discharge electrode (5a) or the ground electrode (5b) protrudes too much into the combustion chamber, there is a risk that it will melt due to the high temperature atmosphere at the time of explosion, which is also thermally disadvantageous.
[発明が解決しようとする課題]
従来のイオン電流検出用点火プラグは以上のように、グ
ランド電極(5b)が放電用電極(5a)を覆うように
構成されており、陽イオンの検出性を阻害しているので
、イオン電流の検出感度を十分に向上させることが困難
であり、且つ、熱的にも不利になるという問題点があっ
た。[Problems to be Solved by the Invention] As described above, the conventional spark plug for detecting ion current is configured such that the ground electrode (5b) covers the discharge electrode (5a), which improves the detectability of cations. Therefore, there were problems in that it was difficult to sufficiently improve the detection sensitivity of the ion current, and it was also disadvantageous thermally.
この発明は上記のような問題点を解決するためになされ
たもので、高熱による熔融問題を生じることなく検出感
度を向上させたイオン電流検出用点火プラグを得ること
を目的とする。The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain a spark plug for detecting ionic current that has improved detection sensitivity without causing the problem of melting due to high heat.
U課題を解決するための手段]
この発明に係るイオン電流検出用点火プラグは、グラン
ド電極を放電用電極の側面に対して対向配置させたもの
である。Means for Solving Problem U] The ionic current detection spark plug according to the present invention has a ground electrode disposed opposite to a side surface of a discharge electrode.
[作用]
この発明においては、気筒の爆発行程時にはグランド電
極の先端と放電用電極の側面との間で放電させ、イオン
電流検出時には燃焼室壁と放電用電極との間で陽イオン
による空間電流を発生させる。[Operation] In this invention, during the explosion stroke of the cylinder, a discharge is caused between the tip of the ground electrode and the side surface of the discharge electrode, and when detecting an ion current, a space current due to cations is generated between the combustion chamber wall and the discharge electrode. to occur.
[実施例]
以下、この発明の一実施例を図について説明する。第1
図はこの発明の一実施例を示す側面図であり、(5)、
(5a)、(5b)は前述と同様のものである。又、こ
の発明が適用されるイオン電流検出装置は第3図に示し
た通りである。[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a side view showing one embodiment of the present invention, (5),
(5a) and (5b) are the same as described above. Further, an ion current detection device to which the present invention is applied is as shown in FIG.
第1図において、中心電極即ち放電用電極(5a)は長
く突出されている。又、グランド電極(5b)は、突出
量ができるだけ小さくなるように、点火プラグ(5)の
ハウジング側に近接配置され、且つ、放電用を極(5a
)の側面に対して対向配置されている。In FIG. 1, the center electrode, ie, the discharge electrode (5a), is long and protrudes. Further, the ground electrode (5b) is arranged close to the housing side of the spark plug (5) so that the amount of protrusion is as small as possible, and the ground electrode (5b) is arranged close to the housing side of the spark plug (5), and is connected to the electrode (5a) for discharge.
) is placed opposite to the side of the
次に、第3図を参照しながら、第1図に示したこの発明
の一実施例の動作について説明する。Next, referring to FIG. 3, the operation of the embodiment of the present invention shown in FIG. 1 will be described.
まず、気筒の爆発行程時においては、グランド電極(5
b)の先端と放電用電極(5a)の側面との間で放電が
行われ、爆発により、燃焼室内には大量の陽イオンが発
生する。First, during the explosion stroke of the cylinder, the ground electrode (5
A discharge occurs between the tip of the discharge electrode (5a) and the side surface of the discharge electrode (5a), and a large amount of cations are generated within the combustion chamber due to the explosion.
続いて、イオン;流Iを検出する場合には、燃焼室壁(
ハウジング)と放電用電極(5a)との間で、陽イオン
による空間電流を発生させる。このとき、グランド電極
(5b)は、放電用電極(5a)をほとんど覆っていな
いので、空間電流を阻害することはない。又、グランド
t i (5b)は、ハウジング側からほとんど突出し
ていないので、高熱による熔融などの障害を生じること
はない。Subsequently, when detecting the ion flow I, the combustion chamber wall (
A space current is generated by positive ions between the discharge electrode (5a) and the discharge electrode (5a). At this time, the ground electrode (5b) hardly covers the discharge electrode (5a), so the space current is not obstructed. Moreover, since the gland t i (5b) hardly protrudes from the housing side, it will not cause problems such as melting due to high heat.
こうして、燃焼室内にある陽イオンは、全て放電用電極
(5a)に流れ、イオン電流工の検出感度は向上する。In this way, all of the cations in the combustion chamber flow to the discharge electrode (5a), improving the detection sensitivity of the ion current.
尚、上記実施例では、グランド電極(5b)を放電用電
極(5a)の側面の一方向のみに対向させたが、第2図
のように、複数のグランド電極(5b)を放電用電極(
5a)の両側面から対向させてもよい。In the above embodiment, the ground electrode (5b) was opposed to only one direction of the side surface of the discharge electrode (5a), but as shown in FIG.
5a) may be opposed from both sides.
この場合、爆発行程時において放電位置が固定されず、
最も放電し易い一方のグランド電極(5b)との間で火
花が生じるので、空燃比や燃焼ガス流量等の種々の燃焼
条件によって燃焼性及びイオン電流検出性が影響を受け
ることがない。従って、イオン電流Iのレベルを一定に
改善することができ、更に信頼性の高い検出が可能とな
る。In this case, the discharge position is not fixed during the explosion stroke,
Since sparks are generated between the ground electrode (5b), which is the one that is most likely to discharge, flammability and ion current detectability are not affected by various combustion conditions such as the air-fuel ratio and the flow rate of combustion gas. Therefore, the level of the ion current I can be improved to a constant level, and even more reliable detection becomes possible.
又、複数のグランド電極(5b)を用いる場合、第2図
のように2極に限らず、例えば4極として、放電用電極
(5a)の4方向の側面から対向させてもよい。Moreover, when using a plurality of ground electrodes (5b), the number of electrodes is not limited to two as shown in FIG. 2, but for example, four electrodes may be used, and they may be opposed from the side surfaces of the discharge electrode (5a) in four directions.
[発明の効果]
以上のようにこの発明によれば、グランド電極を放電用
電極の側面に対して対向配置させ、爆発行程時にはグラ
ンド電極の先端と放電用電極の側面との間で放電させ、
イオン電流検出時には燃焼室壁と放電用電極との間で空
間電流を発生させるようにしたので、高熱による熔融問
題を生じることなく検出感度を向上させたイオン電流検
出用点火プラグが得られる効果がある。[Effects of the Invention] As described above, according to the present invention, the ground electrode is arranged opposite to the side surface of the discharge electrode, and during the explosion stroke, discharge is caused between the tip of the ground electrode and the side surface of the discharge electrode,
When detecting ionic current, a space current is generated between the combustion chamber wall and the discharge electrode, so it is possible to obtain a spark plug for detecting ionic current with improved detection sensitivity without causing melting problems due to high heat. be.
第1図はこの発明の一実施例を示す側面図、第2図はこ
の発明の他の実施例の要部を示す側面図、第3図は一般
的なイオン電流検出装置を示す回路図、第4図及び第5
図はそれぞれ従来のイオン電流検出用点火プラグを示す
側面図である。
(5)・・点火プラグ (5a)・・・放電用電極
(5b)・・・グランド電極
尚、図中、同一符号は同−又は相当部分を示す。FIG. 1 is a side view showing one embodiment of this invention, FIG. 2 is a side view showing main parts of another embodiment of this invention, and FIG. 3 is a circuit diagram showing a general ion current detection device. Figures 4 and 5
Each figure is a side view showing a conventional ion current detection spark plug. (5) Spark plug (5a) Discharge electrode (5b) Ground electrode In the drawings, the same reference numerals indicate the same or corresponding parts.
Claims (1)
ウジングに接続され且つ前記放電用電極の側面に対して
対向配置されたグランド電極とを備えたイオン電流検出
用点火プラグ。A spark plug for ionic current detection, comprising a discharge electrode serving as a center electrode to which a high voltage is applied, and a ground electrode connected to a housing and disposed opposite to a side surface of the discharge electrode.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP25513790A JPH04134180A (en) | 1990-09-27 | 1990-09-27 | Spark plug for detecting ion current |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP25513790A JPH04134180A (en) | 1990-09-27 | 1990-09-27 | Spark plug for detecting ion current |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH04134180A true JPH04134180A (en) | 1992-05-08 |
Family
ID=17274600
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP25513790A Pending JPH04134180A (en) | 1990-09-27 | 1990-09-27 | Spark plug for detecting ion current |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH04134180A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0559438A2 (en) * | 1992-03-03 | 1993-09-08 | Ngk Spark Plug Co., Ltd | A misfire detector device for use in an internal combustion engine |
-
1990
- 1990-09-27 JP JP25513790A patent/JPH04134180A/en active Pending
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0559438A2 (en) * | 1992-03-03 | 1993-09-08 | Ngk Spark Plug Co., Ltd | A misfire detector device for use in an internal combustion engine |
EP0559438A3 (en) * | 1992-03-03 | 1995-04-19 | Ngk Spark Plug Co |
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