Abstract: An insulator for a spark plug including a first portion; a second portion located on the rear side of the first portion, an outer diameter F at a front end of the second portion being smaller than an outer diameter of the first portion; a third portion located on the front side of the first portion, an outer diameter D at a rear end of the third portion being smaller than the outer diameter of the first portion and the outer diameter F at the front end of the second portion; a first slope portion connecting the first portion and the second portion; and a second slope portion connecting the first portion and the third portion. A length A of the second slope portion and a length B of the first slope portion satisfy 2.0?A/B?3.9, and 0.50?D/F?0.88 is satisfied.

Abstract: In a spark plug 100, the outer diameter of a tool engaging portion 1e formed on a main metal member 1 is not larger than 14 mm. An insulator 2 is provided with a expanded diameter portion (2e) positioned within the main metal member 1 and projecting radially outward from an outer circumferential surface of the insulator, and an intermediate trunk portion (2g) adjacent to an axial front side of the expanded diameter portion (2e) and having a cylindrical outer circumferential surface. The inclined portion (2j) has a linearly inclined outer circumferential surface formed in a position so as to connect the expanded diameter portion (2e) and intermediate trunk portion (2g), and formed so that in orthogonal projections with respect to a plane of projection parallel to an axis O, the diameters become smaller from the side of the expanded diameter portion (2e) toward that of the intermediate trunk portion (2g).

Abstract: In an installation structure of a glow plug with a combustion pressure sensor, a seat surface is provided in an installation hole formed in the engine so as to penetrate from outside into a combustion chamber of the engine. A contact surface is formed in the glow plug. The glow plug is partly inserted into the installation hole and is fixed via a ring shaped gasket to the engine so that the glow plug comes in pressurized contact with the engine in an axial direction of the installation hole. With the installation structure mentioned above, the elastic member is elastically more deformable in an axial direction of the installation hole than a portion of the glow plug on which the combustion pressure sensor is mounted.

Abstract: A spark plug having a metal shell accommodating a dielectric core through which an electrode extends and terminates at one end in a tip spaced by a spark gap from an overlying ground wire that is bent between its ends and joined to the shell. That surface of the ground wire which confronts the electrode is grooved to enlarge its area and enable the wire to react like a bimetallic element in response to changes in its temperature and vary the size of the spark gap.

Abstract: An igniter plug having a center conductor, an insulator and a conductive outer shell. The insulator surrounds and supports the center conductor axially within the shell along a substantial portion of the length of the center conductor. The insulator is of reduced diameter toward the discharge end of the igniter and terminates short of the full length of the center conductor. The center conductor extending beyond the insulator terminates short of the discharge end of the igniter and has a discharge electrode of greater diameter than the center conductor affixed to the center conductor end. The electrode terminates at the discharge end of the igniter. A helical compression spring is fitted over the center conductor between the end of the insulator and the electrode to absorb vibrations of the center conductor and electrode.

Abstract: An electrical igniter device for a gas turbine includes a conductive tubular shell having a spark electrode section and an integral body section with an open breach end and a conductive sleeve coaxial with the body section for coaxially supporting one end of a helical spring. Means are described for retractably supporting the shell, sleeve and spring within a protective cylinder wherein the pressure in the combustion chamber exceeds the force exerted by the spring.

Abstract: A spark plug for an internal combustion engine, the spark plug comprising a casing, a center electrode, a connector pin for the center electrode, and a plunger adapted to be axially displaced within the spark plug by the compression pressure as pressure builds in the cylinder, the plunger first closes a set of contacts in the spark plug causing current to flow in the primary side of an ignition coil, then closes a second set of contacts in the spark plug connecting the center electrode to the secondary side of the ignition coil, and finally opens the first set of contacts causing a large voltage to be induced in the secondary side which voltage is applied to the center electrode.

Abstract: An igniter plug having a center conductor, an insulator and a conductive outer shell. The insulator surrounds and supports the center conductor axially within the shell along a substantial portion of the length of the center conductor. The insulator is of reduced diameter toward the discharge end of the igniter and terminates short of the full length of the center conductor. The center conductor extending beyond the insulator terminates short of the discharge end of the igniter and has a discharge electrode of greater diameter than the center conductor affixed to the center conductor end. The electrode terminates at the discharge end of the igniter. A helical compression spring is fitted over the center conductor between the end of the insulator and the electrode to absorb vibrations of the center conductor and electrode.