Komaki, Japan
Komaki, Japan

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Patent
NGK Spark Plug Co. | Date: 2017-05-03

To suppress breakage at a connection region where a front end coil and a rear end coil are connected, provided is a method of producing a glow plug including a sheath tube that extends in an axial direction and whose front end is closed, a front end coil that is disposed in the sheath tube and that is connected to a front end portion of the sheath tube, and a rear end coil that is disposed in the sheath tube and that is connected to a rear end portion of the front end coil. The method includes a welding step of, by melting a front end portion of the rear end coil, welding the rear end portion of the front end coil and the front end portion of the rear end coil such that at least part of the rear end portion of the front end coil is embedded in the front end portion of the rear end coil while being surrounded by the front end portion of the rear end coil. In the method, a main component of the front end coil is tungsten (W) or molybdenum (Mo), and a melting point of the rear end coil is lower than a melting point of the front end coil.


Patent
NGK Spark Plug Co. | Date: 2017-05-03

To ensure oxidation resistance of a glow plug in a high temperature environment and simultaneously prevent a short circuit between a tube and a heat-generating coil in the high temperature environment. The glow plug includes: a tube having a closed forward end; a heat-generating coil that is disposed inside the tube, has a forward end electrically connected to the forward end of the tube, and generates heat when energized; and an insulating material that contains MgO as a main component and fills the space between the inner surface of the tube and the heat-generating coil. The tube is formed of an alloy containing Ni in an amount of 50% by weight or more, Cr in an amount of 18% by weight to 30% by weight, Al, and at least one component selected from Y and Zr. The amount of Al is 1% by weight or less, and the total amount of the at least one component selected from Y and Zr is 0.01% by weight to 0.3% by weight.


Patent
NGK Spark Plug Co. | Date: 2017-04-26

To provide a technology that can render an insulator less easily breakable when an axial hole 2 of the insulator is filled with the material of an electrically-conductive seal portion without fixing the position of a tapered portion of the electrically-conductive seal portion to an inside of a flange portion of the insulator. An electrically-conductive seal portion 60 of a spark plug 1 includes a large-diameter seal portion 65, a small-diameter seal portion 67 having an outer diameter smaller than an outer diameter of the large-diameter seal portion, and a tapered seal portion 66 disposed between the large-diameter seal portion and the small-diameter seal portion. An insulator 3 includes a flange portion 31, a first middle-body portion 32 having an outer diameter smaller than an outer diameter of the flange portion, a second middle-body portion 34 having an outer diameter smaller than an outer diameter of the first middle-body portion, and a leg portion 37 having an outer diameter that tapers toward a tip end of the spark plug. The tapered seal portion is disposed inside the first middle-body portion.


Patent
Ngk Spark Plug Co. | Date: 2016-11-14

A wiring substrate includes: a substrate body made from ceramic, having a front surface and a rear surface, and having a through hole penetrating between the front surface and the rear surface; and a heatsink inserted into the through hole. A step portion protruding in a direction perpendicular to an axial direction of the through hole, is formed over an entire periphery on an inner wall surface of the through hole of the substrate body. A flange opposed to the step portion is provided so as to protrude, over an entire periphery on a side surface of the heatsink. A stress relaxing ring is arranged over an entire periphery between the step portion and a joining surface opposed to the step portion. A brazing material is provided between the ring, and the joining surface and the step portion.


Patent
NGK Spark Plug Co. | Date: 2017-05-24

An object is to mitigate the influence, on the accuracy in detecting an ion current value, of a change in the temperature of a detection section which detects the ion current value. A detection section includes first and second conductors and a substrate and is attached such that the substrate is exposed to a space in which ions are generated as a result of combustion of fuel. The substrate is formed of ceramic, and the first and second conductors are separately embedded and held in the substrate. A measurement section measures the value of current flowing through the second conductor as an ion current originating from the generated ions. An obtainment section obtains the electrical resistance of the substrate between the first conductor and the second conductor. The problem is solved by providing a correction section or a control section. The correction section corrects the current value measured by the measurement section on the basis of the electrical resistance obtained by the obtainment section. The control section controls the supply of electricity to the first conductor such that the electrical resistance obtained by the obtainment section becomes equal to a predetermined value. In the case where the control section is provided, the measurement section measures the current value in a state in which the supply of electricity to the first conductor is controlled by the control section.


Patent
NGK Spark Plug Co. | Date: 2017-05-24

A wiring substrate (130) includes: a substrate body (2,2a,2b) made from ceramic (c1 to c4), having a front surface (3) and a rear surface (4), and having a through hole (6,6a,6b,36) penetrating between the front surface (3) and the rear surface (4); and a heatsink (11,11a,11b,31) inserted into the through hole. A step portion (7) protruding in a direction perpendicular to an axial direction of the through hole, is formed over an entire periphery on an inner wall surface of the through hole of the substrate body. A flange (12) opposed to the step portion (7) is provided so as to protrude, over an entire periphery on a side surface of the heatsink. A stress relaxing ring (16,16a) is arranged over an entire periphery between the step portion (7) and a joining surface (15,15a) opposed to the step portion (7). A brazing material (27) is provided at least between the stress relaxing ring (16,16a) and the joining surface (15) and between the stress relaxing ring (16,16a) and the step portion (7,7a).


Patent
NGK Spark Plug Co. | Date: 2017-06-21

A spark plug has an insulator, a center electrode disposed in an axial hole, a resistor disposed in the axial hole and a seal member disposed between the resistor and the center electrode in the axial hole. The insulator includes an inner-diameter decreasing portion and a small inner-diameter portion. The center electrode includes a head portion supported on the inner-diameter decreasing portion of the insulator. The spark plug satisfies the following conditions: 1.8 mm L; and Cp 11 mm where, assuming a region of the insulator from a boundary of the inner-diameter decreasing portion and the small inner-diameter portion to a rear end of the seal member as a specific region, L is a length of the specific region; D1 is an average inner diameter of the axial hole within the specific region; D2 is an average outer diameter of the specific region; and Cp is L/log(D2/D1).


Patent
NGK Spark Plug Co. | Date: 2017-06-21

There is provided a manufacturing apparatus 200 of a spark plug by working of a workpiece W with dies 230a, 230b and 230c. The workpiece has a metal shell part 40P to be processed into a metal shell of the spark plug and a ground electrode part 50P to be processed into a ground electrode of the spark plug. In the manufacturing apparatus, a position of the ground electrode part is measured in a non-contact manner by a position measurement unit 240 in a state where the workpiece is held in position by a holding unit 210. The dies are controlled by a die control unit 250 so as to adjust the working phase of the dies relative to the workpiece based on the measured position of the ground electrode part and then effect working, with the dies, of the workpiece to form a thread portion on an outer circumferential surface 42P of the metal shell part.


Patent
NGK Spark Plug Co. | Date: 2017-06-21

There is provided an inspection method of a spark plug insulator. The spark plug insulator includes a collar portion, a rear body portion located in rear of the collar portion and a leg portion located in front of the collar portion. The inspection method includes: performing measurement of a distance in a radial direction of the insulator between an outer circumferential surface of the leg portion at a first measurement point and an outer circumferential surface of a portion of the insulator other than the leg portion at a second measurement point, wherein the measurement is performed at a plurality of positions in a circumferential direction of the insulator with no contact to the measurement target; determining, as a circular runout, a difference between maximum and minimum values among measurement results of the distance; and making pass/fail judgment of the insulator based on the determined circular runout.


Patent
Ngk Spark Plug Co. | Date: 2017-01-06

A spark plug includes a central electrode and a noble metal tip, which are joined together with a fusion portion interposed therebetween. A tip-adjoining boundary of the fusion portion has a shape that curves convexly toward the fusion portion. A central-electrode-adjoining boundary of the fusion portion has a shape that curves convexly toward the central electrode. The outline of a portion of the fusion portion exposed to the outer surface has a shape that curves concavely into the inner side of the fusion portion.

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