Patent application number | Description | Published |
20090102346 | SEALING MEMBER FOR SPARK PLUG - 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 | 04-23-2009 |
20120153801 | SPARK PLUG AND METHOD FOR PRODUCING SPARK PLUG - A spark plug includes a tubular metallic shell extending in the direction of an axis and having a tool engagement portion formed through extrusion. The tool engagement portion has a 12-point shape which is a sectional shape taken orthogonally to the axis and has a plurality of protrusions and recesses provided alternately. As viewed in a section taken orthogonally to the axis, when D (mm) represents the diameter of a circle which passes radially through the outermost positions on the protrusions, and d (mm) represents the diameter of a circle which passes radially through the innermost positions on the recesses, the relational expression 0.45≦(D−d)/2≦0.75 is satisfied. The spark plug can provide a more reliable restraint on the slippage of a tool at the time of mounting and enables the tool engagement portion to be reliably formed so as to form a desired shape. | 06-21-2012 |
20130162135 | SPARK PLUG - A spark plug includes a ceramic insulator having a tapered rear end stepped portion whose diameter decreases from front to rear and a metal shell having a crimp portion which crimps the rear end stepped portion from the rear end. An area defined by an outer edge of the rear end stepped portion and an inner edge of the crimp portion is 5-25 mm | 06-27-2013 |
20130278133 | SPARK PLUG AND METHOD OF MANUFACTURING THE SAME - A spark plug includes: a rod-shaped center electrode extending in an axial direction; an insulator including a shaft hole that holds the center electrode inside of the shaft hole; a metal shell surrounding and holding a part of the insulator; and a ground electrode including a base end welded to the metal shell. The metal shell and the ground electrode are joined via a fusion portion formed by welding the ground electrode and the metal shell together. When the smallest thickness of the fusion portion in the axial direction is A, when, in a cross section that includes a center line of the ground electrode and is parallel to the axis, a length of a ground-electrode-side melted boundary formed between the fusion portion and the ground electrode is B, and when the ground electrode thickness is C, conditions of A≧0.2 mm and B >C are satisfied. | 10-24-2013 |
20140065915 | METHOD FOR MANUFACTURING SPARK PLUG - A method for manufacturing a spark plug includes an assembling step of assembling an insulator into a metallic shell by insertion of the insulator into the metallic shell from an axially rear end opening portion of the metallic shell. The assembling step includes a displacement restricting step of restricting a relative positional displacement between the metallic shell and the insulator in a radial direction intersecting with the axial direction so as to reduce eccentricity between the axis of the metallic shell and the axis of the insulator to a predetermined value or less, while allowing a relative positional displacement between the metallic shell and the insulator in the axial direction. In the assembling step, whether or not the insulator is cracked in the assembling step is judged by detecting acoustic emission from the insulator. | 03-06-2014 |
20140111079 | SPARK PLUG - In a spark plug, at least one of a center electrode and a ground electrode has a cover portion and a core portion having a different thermal expansion coefficient. The core portion has a concave portion and a convex portion formed at a front end thereof. The convex portion is such that, in a cross section passing through a barycenter of a front surface of the electrode and also passing through the convex portion, an area of the convex portion delimited by a line perpendicular to a bisector of the convex portion and passing through a point 0.2 mm shifted from a front end of the convex portion in the direction of the bisector is smaller than an area of a triangle formed by connecting the front end of the convex portion and intersections of the line perpendicular to the bisector and a contour of the convex portion. | 04-24-2014 |
20150188293 | SPARK PLUG - A spark plug includes a center electrode, an insulator, a metallic shell, and a seal member for providing a seal between the insulator and the metallic shell. The insulator includes a first portion, a second portion located axially forward of the first portion and being smaller than the first portion, and an insulator first-diameter-reducing-portion whose outside diameter reduces forward and which connects the first portion and the second portion. The metallic shell includes a protrusion that includes a metallic shell diameter-reducing-portion whose inside diameter reduces forward. The seal member is disposed between the insulator first-diameter-reducing-portion and the metallic shell diameter-reducing-portion. A relationship θ | 07-02-2015 |
20150188294 | SPARK PLUG - A spark plug includes an insulator including an axial hole and having an outer periphery with a tapered outer face; a metal shell having a thread portion and a tapered inner face; and a circular packing sandwiched between the tapered outer face of the insulator and the tapered inner face of the metal shell. On at least one cross section including the axis, (A/B)≧3.1, B≧0.25, and (A+B)≦2.0 are satisfied, where A represents a length of (a difference between an effective diameter of the thread portion and an inner diameter at a rear end of the tapered inner face)/2, and B represents a length of (a difference between the inner diameter at the rear end of the tapered inner face and an inner diameter at a front end of the tapered inner face)/2. | 07-02-2015 |