Abstract: A method for manufacturing an ignition plug is provided. The method includes: preparing an insulator having a cavity provided at a leading end portion thereof by disposing a leading end of a center electrode more inwards in an axial hole than a leading end of the insulator; building the insulator in an interior of a metal shell; disposing a ground electrode at a leading end portion of the metal shell; positioning a center of a through hole of the ground electrode and a center of the cavity of the insulator; and welding the ground electrode and the metal shell together after the positioning step.

Abstract: An IG-off-timer measures the time t_off from when an engine is stopped, or an ignition is turned off. An ECU sequentially memorizes an estimated temperature of each of heat generating portions as a memorized temperature. Immediately after the engine is re-started, the ECU sets an initial value of the estimated temperature of each heat generating portion in such a manner that the initial value reflects a temperature drop of the heat generating portion in the deactivation period of the engine. The temperature of the heat generating portion is thus accurately estimated even after re-starting of the engine. The heat generating portions are thus appropriately protected.

Abstract: It is an object of the invention to provide a method of producing a spark plug in which, in order to reduce the size of the spark plug, the diameter of a center electrode can be reduced while maintaining the heat dissipation property of the center electrode, and also such a spark plug. A columnar member 220 in which an outer skin member 21 made of a high refractory Ni alloy, and a core member 23 made of a copper alloy having a high thermal conductivity are clad, and which is columnarly extended can be configured by extrusion molding into a state where the thickness of the outer skin member 21 is substantially uniform (extrusion molding step). A flange portion 305 and a tip end portion 301 are formed in the columnar member 220 to obtain an electrode intermediate member 320 (tip end portion/flange portion forming step). In a middle trunk portion 303 of the electrode intermediate member 320, the thickness of the outer skin member 21 is maintained.

Abstract: A spark plug including: a center electrode (20); an insulator (10) having an axial hole (12) extending in an axial direction of the center electrode (20) and holding the center electrode (20) in the axial hole (12); a cylindrical metal shell (50) surrounding the insulator (10) and holding the insulator (10); and a ground electrode (30) having first and second end portions, an end face (35) of one end portion (32) being joined to a tip face (57) of the metal shell (50) and which is bent so that the other end portion (31) is opposed to the center electrode (20). An axial line (P) of the metal shell (50) and an axial line (O) of the insulator (10) deviate from one another so that a relationship A>B is satisfied for distances A and B as defined herein.

Abstract: An ECU estimates the temperatures of the heat generating portions provided in a drive force transmission system, or a transaxle, a rear differential, and a torque coupling, in correspondence with not only the rotational speed (the differential rotational speed) of each heat generating portion and the torque transmission rate of the torque coupling but also the outside temperature detected by an outside temperature sensor. If the estimated temperature of any of the heat generating portions exceeds a respective predetermined temperature, the ECU controls operation of the torque coupling to suppress overheating of the heat generating portion. That is, the temperature of each heat generating portion is accurately detected through a simplified structure and overheating of the heat generating portion is effectively suppressed.

Abstract: A spark plug includes a ground electrode formed with a flat region and a convex curved region on an outer peripheral surface thereof. The flat region is located on a front end of the ground electrode and has a length of 0.2 mm or more from a front end face of the ground electrode in a longitudinal direction of the ground electrode. The ground electrode satisfies the following dimensional condition (1) with respect to first and second cross sections of the ground electrode taken through the convex curved region and the flat region in directions perpendicular to the longitudinal direction of the ground electrode, 0.950?(S2/L2)/(S1/L1)?0.995 ??(1) where S1 is the area of the first cross section; L1 is the perimeter of the first cross section; S2 is the area of the second cross section; and L2 is the perimeter of the second cross section.

Abstract: A spark plug including a ground electrode and a noble metal tip joined to a distal end portion of the noble metal tip. The noble metal tip is joined to the ground electrode via a molten bond in which the noble metal tip and the ground electrode are fused. A protruding length of the noble metal tip is 0.3 mm or more. Regarding the molten bond, relationships 50?S1+S2?120 and ?1>?2 are satisfied for a first molten angle S1°, a second molten angle S2°, a first contact angle ?1° and a second contact angle ?2° as defined herein.

Abstract: A sealing member for a cylindrical spark plug having a metal shell with threaded ridges thereon to be screwed into a mounting hole of a combustion engine, the sealing member comprised of a piece of annular sheet material made of austenitic stainless steel or ferritic stainless steel that is folded back in a radial direction so as to form a region where at least two or more layers of the sheet material are overlapped in an axial direction

Abstract: A spark plug configured such that a noble-metal tip is welded to each of a front end portion of a center electrode and a distal end portion of a ground electrode. The noble-metal tip of the center electrode or the ground electrode, whichever has a weld metal zone having a greater projected area where an electrode base metal and a metal of the noble metal tip are fused together, is made greater in exposed length of the noble-metal tip. In a preferred embodiment, the projected area of the weld metal zone and the exposed length of the noble-metal tip on the ground electrode side are made greater than those on the center electrode side.

Abstract: There is provided a test method for detecting the presence or absence of a defect in a spark plug insulator, including a reference voltage determination process, a test area determination process, a test voltage determination process and a current detection process. In the reference voltage determination process, a reference voltage VF is determined. In the test area and voltage determined processes, test area and voltage are determined so as not to incur a flashover on the basis of a reference insulator of the same material, shape and size as the spark plug insulator when the reference insulator is placed in position between first and second test electrodes. In the current detection step, the test voltage is applied between the first and second test electrodes to detect an electric current between the first and second test electrodes.

Abstract: A laser ignition device for irradiating and condensing laser beams in a combustion chamber of an internal combustion engine so as to ignite fuel particles within the combustion chamber, includes: a laser beam generating unit for emitting the laser beams; and a condensing optical member for guiding the laser beams into the combustion chamber such that the laser beams are condensed in the combustion chamber, wherein the laser beam generating unit comprises a Beam Parameter Product (BPP) laser beam generating unit which emits the laser beams with a BPP value of no more than 20 mm·mrad (radius·half angle).

Abstract: A plasma-jet spark plug comprising an insulator and a ground electrode which are disposed apart from each other in an axial direction (O) to prevent a damage of the insulator. The spark plug is capable of reducing an energy loss of the ejected plasma by defining a dimension of a clearance between the insulator and the ground electrode whereby deterioration of the ignitability of the plasma-jet spark plug is prevented. Clearance having a first clearance dimension “a” is formed between a front end of the insulator and the ground electrode. Since a volume S of a cavity formed at the front end side of the insulator is set to 10 mm3 or less, plasma formed in the cavity is prevented from spreading. Further, since the first clearance dimension “a” satisfies a<=0.5 mm, the plasma ejected from the cavity is ejected toward the outside of the spark plug while keeping sufficient energy, so that it is unlikely that an energy leak in the first clearance occurs on the way to an orifice.

Abstract: A plasma jet spark plug and a manufacturing method therefor are disclosed. In a state in which a noble-metal chip having a flange-like outwardly projecting portion is disposed in a communication section of a ground electrode, an electrode base metal of the ground electrode is disposed in a stepped engagement portion of a metallic shell, which retains an insulator therein. While being pressed against a front end portion of the insulator, the noble-metal chip is joined to the electrode base metal, whereby a clearance between the ground electrode (electrode base metal) and the front end portion of the insulator can be closed. Therefore, energy of plasma generated within the cavity does not leak.

Abstract: A spark plug (100) including a center electrode (130) and a ground electrode (140), which is formed by joining a ground electrode chip (143) to a ground electrode base material (141) via an intermediate member (142). A method for producing the spark plug (100) includes providing a projecting portion (142p) on the intermediate member (142), and projection-welding the intermediate member (142) to the ground electrode base material (141) by means of the projecting portion (142p), to thereby join the intermediate member 142 to the ground electrode base material (141). Further, the intermediate member (142) of the spark plug (100) includes a cylindrical columnar portion (142e) which is joined to the ground electrode chip (143), and a flange portion (142d) which is joined to the ground electrode base material (141) and which flange portion (142d) has a diameter greater than that of the cylindrical columnar portion (142e).

Abstract: A ground-electrode spark portion 32 is formed from a noble metal which contains Pt as a main component, and is joined to a main metal portion of the ground electrode 4 via an alloy layer which has a thickness ranging from 0.5 ?m to 100 ?m and in which the noble metal that constitutes the ground-electrode spark portion 32 and the metal that constitutes the main metal portion of the ground electrode 4 are alloyed with each other. The ground-electrode spark portion 32 is configured such that a distal end surface 32t facing a spark discharge gap g is smaller in diameter than a bottom surface 32u joined to the ground electrode 4; and the distal end surface 32t is protrusively located beyond the side surface 4s of the ground electrode 4.

Abstract: A plasma-jet spark plug includes a metal shell, an electrical insulator retained in the metal shell, a center electrode held in an axial hole of the electrical insulator to define a cavity by a front end face of the center electrode and an inner circumferential surface of the insulator axial hole and a ground electrode arranged on a front end of the electrical insulator. The ground electrode has an opening defining portion defining an opening for communication between the cavity and the outside of the spark plug. The opening defining portion is located radially inside of or in contact with a first imaginary circular conical surface where the first imaginary circular conical surface has an axis coinciding with an axis of the spark plug and a vertex angle of 120° opening toward a front end of the spark plug and passing through a front edge of the insulator axial hole.

Abstract: A plasma-jet spark plug includes a metal shell, an electrical insulator retained in the metal shell, a center electrode held in an axial hole of the electrical insulator to define a cavity by a front end face of the center electrode and an inner circumferential surface of the insulator axial hole and a ground electrode arranged on a front end of the electrical insulator. The ground electrode has an opening defining portion defining an opening for communication between the cavity and the outside of the spark plug. The opening defining portion is located radially inside of or in contact with a first imaginary circular conical surface where the first imaginary circular conical surface has an axis coinciding with an axis of the spark plug and a vertex angle of 120° opening toward a front end of the spark plug and passing through a front edge of the insulator axial hole.

Abstract: An inexpensive and compact modulator-integrated light source is capable of obtaining an extinction ratio of 10 dB sufficient for use in optical communication without requiring an amplifier or temperature regulating mechanism. The modulator-integrated light source is composed of a semiconductor laser and modulator integrated on high-resistance semiconductor substrate 1. The electroabsorption optical modulator has P-electrode 14 and N-electrode 32 which are arranged on one surface of high-resistance semiconductor substrate 1 and to which a prescribed bias voltage is applied, and the electroabsorption optical modulator is constructed to satisfy the condition: L×B?2000 ?m·Gb/s, where L is the length of the electroabsorption optical modulator and B is the operating frequency.

Abstract: A spark plug including an insulator having an axial hole in an axial direction of the spark plug; a center electrode disposed in a tip end side of the axial hole of the insulator; a metal shell surrounding the insulator; a first ground electrode including a first ground electrode body having one end joined to the metal shell, and a noble metal tip joined to an inner side face of another end portion of the first ground electrode body and disposed opposite a tip end face of the center electrode across a first discharge gap. One end of the second ground electrode is bonded to the metal shell, and the another end is disposed opposite a side peripheral face of said center electrode or a side peripheral face of said insulator across a second discharge gap. Furthermore, the spark plug is characterized as having a distance t and an included angle ? as defined herein.

Abstract: A distributed-feedback semiconductor laser as a direct modulation light source with a modulation rate over 10 Gb/s having (1) a low threshold current characteristic, (2) a high single-mode characteristic, (3) a high resonant frequency (fr) characteristic, (4) a high temperature characteristic, and (5) adaptability to wide wavelength band and an extremely short active region. The distributed-feedback semiconductor laser 1 comprises an active region 30 for generating the gain of the laser beam and a diffraction grating 13 formed in the active region 30. Out of the two front and back end surfaces sandwiching the active region 30, the front end surface 1a has a reflectivity of 1 percent or less, and the back end surface 1b has a reflectivity of 30 percent or more when viewed from the back end surface 1b toward the front. The coupling coefficient ? of the diffraction grating 13 is 100 cm?1 or more, and the length L of the active region 30 is 150 ?m or less.