Denso Corporation

Nippon Soken, Inc.

Yuya Abe

Akimitsu Sugiura

Masamichi Shibata

Shinichi Okabe

Yoshihiro Nakase

Kenji Kanehara

Shingo Morishima

Masayoshi Sugino

Noriaki Nishio

Daisuke Shimamoto

Shohei Ishida

Kazuki Fukatsu

Shun Sugita

Yoshitaka Tomita

A spark plug includes a ground electrode facing a distal end surface of a center electrode. In a main body of the ground electrode, a first slanted surface is formed at a portion on a side facing the distal end surface and upstream of the center electrode relative to the airflow, a facing portion, a second slanted surface is formed at a portion on a side opposite to the side facing the distal end surface and upstream of the center electrode relative to the airflow, and when T represents a thickness of the main body of the ground electrode and Su represents a distance from a connection between the first slanted surface and the second slanted surface to the facing portion, 2T/16&#x2264;Su&#x2264;8T/16.

Spark plug including a ground electrode having slanted surfaces and a facing portion facing a distal end surface of a center electrode

On a base part forming a ground electrode in a spark plug, a facing surface is formed facing a distal end surface of a central electrode to have a shortest gap between the facing surface and the central electrode. A first slope surface is formed on an upper surface of the base part. A downstream-side end surface is formed parallel with a virtual plane, and connected to the first slope surface. A second slope surface is formed on a lower surface of the base part, connected to a downstream-side end surface. An opposing surface is formed on the lower surface of the base part. A width of the facing surface is wider than a width of the opposing surface. A first angle of the facing surface to the first slope surface satisfies a relationship of 10&#xb0;&#x2264;&#x3b8;&#x2264;40&#xb0;.

Spark plug that prevents gas turbulence in the discharge space

A spark plug includes a main ground electrode having a main connecting portion connected to the housing and forming a discharge gap between the main ground electrode and the center electrode, and a sub ground electrode having a sub connecting portion connected to the housing. The direction on which the main connecting portion and a plug center axis are arranged is set to be perpendicular to an air flow direction of an air stream in the combustion chamber. The sub connecting portion is located in a downstream side than the main connecting portion. The tip end position of the sub ground electrode in the plug axial direction is located in farther tip end side than that of the main ground electrode is. The sub ground electrode is configured such that an end point of the discharge spark is movable on the sub ground electrode.

Spark plug for internal combustion engine

A barrier discharge ignition apparatus has a tip end exposed to a combustion chamber of an internal combustion engine and, when subjected to a high-frequency high-voltage AC burst, generates streamer discharges for igniting a fuel/air mixture in the combustion chamber. A central electrode of the apparatus, covered by a dielectric layer and coaxially enclosed in a ground electrode, extends into the combustion chamber to a greater distance than the ground electrode. An electrode portion close to the tip end of the inner periphery of the ground electrode protrudes towards the dielectric layer, for creating a localized high-density electric field. The streamer discharges thereby enter both the to combustion chamber and also a discharge chamber of the ignition apparatus.

Barrier discharge ignition apparatus for internal combustion engine

An ignition system for an internal combustion engine includes a discharge portion of the center electrode in which a part thereof is surrounded by a bottom portion and a tubular tip portion of the center dielectric, the part of the discharge portion and the tubular tip portion are projected into a combustion chamber of the internal combustion engine from a substantially annular tip portion of the ground electrode that opens to the combustion chamber at a distal end of the ground electrode, a diameter-changing portion formed by reducing a diameter of a part of the tubular tip portion in a radial direction gradually as approaching toward a tip thereof, and a thin-walled portion formed by reducing a thickness of the tip of the tubular tip portion.

Ignition system

In an ignition device, a base section of a discharge chamber is formed by a part of a central dielectric body. A front section of a ground electrode and a front end section of the central dielectric body are projected toward a combustion chamber of a head cylinder of an internal combustion engine by a predetermined height which is measured from a top ceiling wall of the head cylinder. The predetermined height of the front end section of the central dielectric body projected into the inside of the head cylinder is the same or higher than the predetermined height of the front end section of the ground electrode projected into the inside of the head cylinder. The predetermined height of the front end section of the ground electrode is within a range of 3 mm to 25 mm.

Ignition device

A laser ignition apparatus includes a housing that has a male-threaded portion for fixing the housing and a hexagonal portion for tightening the male-threaded portion. Between a combustion chamber-side end of the male-threaded portion and an anti-combustion chamber-side end of the hexagonal portion, there is defined a non-optical element arrangement region in which none of an introducing optical element, an enlarging optical element and a focusing optical element of the apparatus is arranged. At one of a combustion chamber-side end and an anti-combustion chamber-side end of the non-optical element arrangement region, there is formed a reference surface that extends perpendicular to an axial direction of the housing. One of the introducing optical element, the enlarging optical element and the focusing optical element is received in the housing in such a manner as to be elastically pressed against the reference surface from outside of the non-optical element arrangement region.

Laser ignition apparatus

In a high frequency plasma generation system, a magnetic resonance section is provided as a frequency multiplier section between a discharge circuit and a power booster circuit. The magnetic resonance section extracts from a fundamental wave of a predetermined frequency generated by a frequency generator higher harmonic components, which are multiplied waves of the predetermined frequency and as high as two or more integer times of the fundamental wave. A resonance frequency of the power booster circuit and a first resonance coil is set to be equal to the frequency of the multiplied wave and match to equal a resonance frequency of the discharge circuit and a second resonance coil of the magnetic resonance section when a discharge electrode and a ground electrode are in a predetermined pressure range.

Growing community of inventors

Kariya, Japan

Yuya Abe