Ngk Spark Plug Company, Limited

Daisuke Kasahara

Hiroyuki Kameda

Daisuke Nakano

Naofumi Yamamura

Yoshikuni Sato

Naoyuki Mukoyama

Yuichi Yamada

Kei Takahashi

Hirotaka Saito

Naohumi Yamamura

A spark plug includes: a central electrode extending from a front end side to a rear end side along an axis; an insulator including a front end section formed to be a bottomed tube surrounding a tip of the central electrode; a metal shell shaped to be tubular and structured to support the insulator such that the front end section of the insulator projects to the front end side from a front end section of the metal shell; and a plurality of ground electrodes each of which includes a first end forming a discharge gap with the front end section of the insulator and includes a second end connected to the front end section of the metal shell. The plurality of ground electrodes include a pair of ground electrodes different from each other in size of their discharge gaps.

Spark plug having a plurality of ground electrodes

A pressure sensor includes: a housing having a tubular shape, and including a front end including an opening; a diaphragm that is disposed to close the opening, and is structured to deform depending on a pressure exerted on a front side of the diaphragm, and includes a hole extending rearwardly from a front end face of the diaphragm; a sensor element structured to output a signal varying depending on an amount of the deformation of the diaphragm; and a heat receiver including a first portion and a second portion. The first portion is disposed in the hole of the diaphragm, and is joined with an inner periphery of the diaphragm defining the hole. The second portion is formed integrally with the first portion, and is disposed adjacent to a front end of the first portion, and is structured to cover the front end face of the diaphragm.

Pressure sensor having a heat receiver including a first portion and a second portion

A plasma jet plug includes a rod-shaped central electrode, an insulator having an axial hole, a metal shell disposed around the insulator, an orifice electrode electrically connected to the metal shell and located at a distal end side of the insulator, and a gasket that contacts an outer surface of the insulator and an inner surface of the metal shell. The insulator includes a first member, a second member and an inorganic seal layer. The first member has the axial hole and includes a large-diameter portion and a small-diameter portion. The second member has a through hole into which the small-diameter portion is inserted. The second member has an outer surface that contacts the gasket. The inorganic seal layer seals a gap between the first member and the second member. In a section including the axis, the sum of seal lengths is greater than or equal to 3 mm.

Plasma jet plug

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

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

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.

A plasma jet spark plug capable of preventing a channeling progress and having excellent heat conduction. The plasma jet spark plug comprised of: a ceramic insulator having a small diameter portion which assumes a linear shape in an axial direction, and a center electrode has an outer diameter increasing in the order of a frontmost portion, a step portion, a front end portion and a body portion.

A current of sufficient size to form plasma at ignition of a plasma jet ignition plug flows to a spark discharge gap while suppressing noise occurrence. There is provided an ignition apparatus of a plasma jet ignition plug, which includes a resistor R, with one end connected to a diode Ddisposed between the plasma jet ignition plugand a high-voltage generation circuitand with the other end electrically connected to a center electrodeof the plasma jet ignition plug, and a capacitor C, with one end connected to the center electrodeof the plasma jet ignition plugand with the other end grounded.

Ignition apparatus of plasma jet ignition plug

An ignition plug that maintains excellent ignition performance over a long period of time through effective prevention of channeling. The ignition plug includes an insulator having an axial bore, a center electrode inserted into the axial bore, a metallic shell disposed externally of the outer circumference of the insulator, and a ground electrode fixed to a front end portion of the metallic shell. A cavity is defined by the wall surface of the axial bore and the front end surface of the center electrode. The ground electrode includes a body whose distal end portion is disposed away from the front end of the insulator, and a protrusion protruding from the body.

A plasma jet spark plug for igniting an air-fuel mixture in a conventional combustion device such as an internal combustion engine.

A plasma jet ignition plug that reliably prevents current leakage with restraint on variation in the position of a ground electrode relative to an insulator and on overheat of the ground electrode, for stable generation of plasma. The plug includes an insulator having an axial bore extending in the direction of an axis CL, a center electrode inserted in the axial bore, a metallic shell disposed externally of the outer circumference of the insulator, and a ground electrode fixed to the metallic shell, and has a cavity defined by the wall surface of the axial bore and the front end surface of the center electrode. Supports intervene between the insulator and the ground electrode. A space formed radially outward of the supports and a space formed radially inward of the support communicate with each other.

Plasma jet ignition plug and manufacturing method thereof

A plasma jet ignition plug having high ignition performance and high durability. The plasma jet ignition plug comprises a center electrode wherein at least a front end portion including a front end surface of the center electrode contains an oxide of at least one of the rare earth elements in a total amount of 0.5% by mass to 10% by mass inclusive and tungsten (W) in an amount of 90% by mass or greater, or contains iridium (Ir) in an amount of 0.3% by mass to 3% by mass inclusive and W in an amount of 97% by mass or greater.

A plasma jet ignition plug including an insulator having an axial hole extending therethrough in the direction of an axis CL, a center electrode inserted into the axial hole, and a ground electrode disposed frontward of the front end of the insulator. The insulator has a cavity defined by the wall surface of the axial hole and the front end surface of the center electrode and opens frontward. The ground electrode has a through hole for establishing communication between the cavity and an ambient atmosphere. A front end portion of the center electrode is formed into a taper portion whose diameter reduces frontward in the direction of the axis CL. The outside diameter of a front end of the taper portion is smaller than the diameter of the through hole. The cavity has a substantially constant diameter with respect to the direction of the axis CL

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Toyoake, Japan

Daisuke Kasahara