Ngk Spark Plug Company, Limited

Mitsubishi Electric Corporation

Niterra Co., Ltd.

Hiroyuki Kameda

Katsutoshi Nakayama

Daisuke Nakano

Daisuke Kasahara

Naofumi Yamamura

Yoshikuni Sato

Tomoaki Kato

Satoshi Nagasawa

Yoshihiro Matsubara

Kaori Kishimoto

Kenji Ban

Kohei Katsuraya

Kazumasa Yoshida

Naoyuki Mukoyama

Takashi Hashimoto

Kimihiko Tanaya

Yuichi Yamada

Mamoru Musasa

Takahiro Inoue

Taichiro Tamida

Takayoshi Nagai

Yasushi Sakakura

Akira Nakagawa

Tomokazu Sakashita

Masahiro Inoue

Kenji Nunome

Hiroaki Kuki

Tomoaki Aoki

Kohei Usami

Naohumi Yamamura

In an ignition plug, since a ground electrode is formed in a thin-rod-shape or a mesh-like shape, sufficiently strong radicals are locally generated by a barrier discharge, an anti-inflammation effect by the electrode is small, and the growth of a flame is hardly hindered. Furthermore, by making the thickness dimension of a second dielectric facing a discharge region uniform, the barrier discharge is spread over the surface of the second dielectric, the generation of the radicals is maintained, and combustibility after ignition is promoted. Furthermore, because an end portion of a high voltage electrode and a ground electrode are disposed to face each other within a combustion chamber, a fuel gas introduced into the combustion chamber is liable to flow into the discharge region, and is easily ignited by the radicals generated due to the discharge.

Ignition plug and ignition system including the same

A spark plug having an insulator with a front end portion having an annular groove opened to a front side around an axial line. The groove has a width of greater than or equal to 0.2 mm in a radial direction. In a cross section including the axial line, a value D/L obtained by dividing, by a length L, a creepage distance D, from a position P on the frontmost side of a region in which a clearance distance between an outer surface of a front end portion and an inner circumferential surface of a metal shell is less than or equal to 0.1 mm to a connection position between an outer surface of the front end portion and the axial hole, is greater than or equal to 1.1.

Spark plug

A non-thermal equilibrium plasma ignition plug including a tubular metallic shell having an axial hole extending along an axial line, an insulator disposed in such a manner as to form a gap in cooperation with a wall surface of the axial hole at a forward end portion of the metallic shell, and a center electrode held at the center of the insulator, and generates nonequilibrium plasma in response to voltage applied thereto from a power supply. The insulator has a plurality of depressions or protrusions formed on a surface thereof which faces a discharge space therearound.

Non-thermal equilibrium plasma ignition plug and non-thermal equilibrium plasma ignition device

A plasma jet plug has a cavity defined by a surface of a center electrode, an inner surface of an insulator, and a surface of a ground electrode. When a volume of a portion of the cavity on a front side of a front portion of the center electrode is a first volume Vand a volume of a portion of the cavity on a rear side of the front end of the center electrode is a second volume V, the following expression is satisfied:1/2&#x2267;0.20.

Plasma jet spark plug

A spark plug having an insulator, a metallic shell disposed around the insulator, a first ground electrode having a first surface facing a side surface of a center electrode in a radial direction so as to form a first gap, and a second ground electrode having a second surface facing the side surface of the center electrode in the radial direction so as to form a second gap. A relation 60&#xb0;&#x2266;&#x3b8;&#x2266;150&#xb0; is satisfied, where &#x3b8; is a smaller one of angles formed between a first line connecting an axial line of the center electrode and the center of the first surface and a second line connecting the axis and a center of the second surface when viewed from a forward end side toward a rear end side in the direction of the axis.

An ignition apparatus which facilitates improvement in energy efficiency as well as materializing an excellent ignitability through effectively utilizing energy used for inductive discharge as a blowout power. The ignition apparatus is used for an ignition plug that includes a center electrode, a ground electrode and a cavity surrounding at least a portion of a clearance formed between the two electrodes to thereby form a discharge space. The ignition apparatus includes a voltage application portion which applies voltage to the clearance and a power supply portion which supplies electric power to the clearance. In addition, a capacitance portion for storing a capacitance is provided, in parallel with the ignition plug, in a voltage application path of the voltage application portion.

Ignition apparatus and ignition system

There is provided a spark plug for an internal combustion engine, including: a center electrode extending in the direction of an axis of the spark plug and having a core of higher thermal expansion coefficient than that of a front end thereof, the center electrode including a flanged portion radially outwardly protruding on a rear side thereof and a cylindrical portion located closer to a front end of the spark plug than the flanged portion and being smaller in diameter than the flanged portion; an insulator having an axial hole in the direction of the axis to retain the flanged portion in the axial hole with the cylindrical portion held in a loose-fit state in the axial hole; and a metal shell accommodating the insulator, wherein the spark plug satisfies the following condition: Cb&#x3c;Cf where Cb is a difference between an inner diameter of the axial hole and an outer diameter of the cylindrical portion at an arbitrary axial position B in the direction of the axis; and Cf is a difference between the inner diameter of the axial hole and the outer diameter of the cylindrical portion at an axial position F closer to the front end of the spark plug than the axial position B in the direction of the axis.

Spark plug for internal combustion engine

A plasma jet spark plug having increased capacitive discharge current, and thus improved plasma generation efficiency. The plasma jet spark plug includes an insulating body having an axial hole, a center electrode, a metal shell, and a cavity portion formed by the inner peripheral surface of the insulating body and the leading end face of the center electrode. A conductive layer formed from a conductive material is provided on at least one portion of at least one of: (a) a surface on the insulating body outer peripheral surface opposed to the inner peripheral surface of the metal shell, the conductive layer electrically connected to a ground electrode; and (b) a surface on the insulating body inner peripheral surface opposed to the outer peripheral surface of the center electrode, the conductive layer electrically connected to the center electrode.

Plasma jet spark plug and ignition system

An ignition plug providing excellent ignition performance that can be maintained over a long period of time by restraining channeling. The ignition plug includes a ceramic insulator having an axial bore, a center electrode inserted into the axial bore, a metallic shell, and a ground electrode fixed to the metallic shell, and has a cavity defined by an inner circumferential surface of the axial bore and the forward end surface of the center electrode. The axial bore includes a first straight portion and a diameter-reducing portion. As viewed on a section which contains an axis (CL) of the ignition plug, a relational expression &#x3b1;&#x2267;10 is satisfied, where &#x3b1; (&#xb0;) is an acute angle formed by a straight line orthogonal to the axis (CL) and the outline of the diameter-reducing portion.

Plasma jet ignition plug

An ignition system for a plasma jet ignition plug that enables a reduction in production cost and provides excellent ignition performance through improvement of plasma formation efficiency. The ignition system includes a plasma jet ignition plug having a center electrode, a ground electrode, and a cavity surrounding at least a portion of a gap formed between the center electrode and the ground electrode to form a discharge space, and a voltage application section for applying voltage across the gap. The ignition system further includes a capacitance section having a capacitance and provided in parallel with the plasma jet ignition plug between the plasma jet ignition plug and the voltage application section.

Ignition system for plasma jet ignition plug

A spark plug includes a center electrode extending along an axial line, a ground electrode, and a noble metal tip. A center axis of the noble metal tip is displaced from a center axis of the ground electrode toward a base-end side in the axial line. The ground electrode includes an outer layer and an inner layer, and a distal end of the inner layer is closer to the axial line than a base end of the ground electrode. An overlap area between the inner layer and the noble metal tip occupies a ratio of 25% or more in a projective plane defined by projecting, along the center axis, a plane of the ground electrode viewed from a distal-end face on a cross section of the ground electrode in which a maximum cross-sectional area of the inner layer is achieved, among cross sections orthogonal to the center axis.

A spark plug includes a center electrode extending in an axial direction; an insulator formed externally of the outer circumference of the center electrode; a metallic shell formed externally of the outer circumference of the insulator and having a ledge which supports the insulator; and a ground electrode joined to the metallic shell. The insulator has a support portion which faces the ledge. A 'frontward direction' is defined as the direction parallel to the axial direction toward a spark portion formed between the center electrode and the ground electrode. The insulator has a diameter reduction portion whose outside diameter reduces along the frontward direction from the support portion, and a diameter increase portion whose outside diameter increases along the frontward direction from the front end of the diameter reduction portion. This restrains the generation of leak current while maintaining heat resistance of the spark plug.

Spark plug having shaped insulator

A corner of a distal end of a ground-electrode-side noble metal tip of a spark plug is taken as a first corner; a corner of a leading end of a center-electrode-side noble metal tip is taken as a second corner; a corner formed at a starting point where a diameter of the center electrode is reduced is taken as a third corner; a corner of the ground electrode is taken as a fourth corner; a corner closest to the third corner of the corners on the distal end of the ground-electrode-side noble metal tip is taken as a fifth corner; a length of a virtual flying spark path defined between the first corner and the second corner is taken as L; a length of a virtual flying spark path defined between the third corner and the fourth corner is taken as L; a length of a virtual flying spark path defined between the third corner and the fifth corner is taken as L; and Lor L, whichever is shorter, is taken as L, the spark plug fulfills a relational expression of L/L&#x2267;1.1.

A plasma jet ignition plug exhibiting high plasma generation efficiency while restraining occurrence of preignition. Prepresents the position of a rear end of a region of a metallic shell ledge, the region being in contact with an insulator. Prepresents the position of a rear end of a region of the insulator ledge, the region being in contact with the center electrode. Front end surfaces of the metallic shell, the insulator, and center electrode, an imaginary plane Swhich is perpendicular to the axis and contains position P, and an imaginary plane perpendicular to the axis and contains position Pare disposed in this order from front side to rear side along the axis. The axial distance A from the front end surface of the insulator to imaginary plane Sand axial distance B from the imaginary plane Sto imaginary plane Ssatisfy 0.5&#xd7;A&#x2266;B.

A plasma jet ignition plug including a wire-wound resistor for restraining the radiation of noise while allowing application of a sufficiently large current for generation of plasma to a spark discharge gap at the time of ignition. The wire-wound resistor having an inductance of 1 &#x3bc;H to 100 &#x3bc;H inclusive and a resistance of 1&#x3a9; or less, and is provided on at least one of a center electrode and a ground electrode. The wire-wound resistor restrains current which is generated by the influence of stray capacitance present in the plasma jet ignition plug, thereby reducing noise.

Growing community of inventors

Aichi, Japan

Hiroyuki Kameda