{
  "$type": "site.standard.document",
  "description": "Deformation of a seat portion and a protrusion is reduced in a caulking process so as to ensure good air tightness. A spark plug (1) includes an insulating insulator (2) and a metal shell (3). The metal shell (3) includes a caulking portion (19), a seat portion (16) with a tapering surface (31), a…",
  "path": "/patents/960216",
  "publishedAt": "2015-06-10T00:00:00.000Z",
  "site": "at://did:plc:oql6ds5vnff4ugar6rruliwd/site.standard.publication/3mn3ohu7oxx5w",
  "tags": [
    "F02P13/00",
    "NGK SPARK PLUG CO [JP]"
  ],
  "textContent": "Deformation of a seat portion and a protrusion is reduced in a caulking process so as to ensure good air tightness. A spark plug (1) includes an insulating insulator (2) and a metal shell (3). The metal shell (3) includes a caulking portion (19), a seat portion (16) with a tapering surface (31), a thread portion (15) with a thread size equal to or less than M12, and a protrusion (20). The insulating insulator (2) includes a lock portion (14) locked to the protrusion (20), and is secured to the metal shell (3) in a state held between the caulking portion (19) and the protrusion (20). SB/SC ‰¥ 3.5, SB/LB ‰¤ 12.0, and SC/LC ‰¤ 12.0 are satisfied in a case where: the tapering surface (31) has an area of SB (mm 2 ); a seat-portion outer peripheral surface (32) extending from a rear end of the tapering surface (31) in the seat portion (16) has a length of LB (mm); a locked surface (33) locking the lock portion (14) in the protrusion (20) has an area of SC (mm 2 ); and a protrusion inner peripheral surface (34) extending from a tip end of the locked surface (33) toward the tip end side in the protrusion (20) has a length of LC (mm).",
  "title": "SPARK PLUG"
}