公开(公告)号：BRPI0814298A2

公开(公告)日：2015-02-03

申请号：BRPI0814298

申请日：2008-07-31

Applicant: DENSO CORP

Inventor： HANASHI KEN ,  KADOWAKI SATORU ,  HRI TSUNENOBU ,  TSUBOTA KENKA ,  AIDA HIROTAKA ,  ISHIGURO HIROYA

IPC: H01T13/32 ,  H01T13/20 ,  H01T21/02

Abstract: A method of manufacturing a spark plug having an attachment fitting 2, an insulator 3, a center electrode 4 and an earth electrode 5. While fixed to attachment fitting 2, earth electrode 5 has a convex part 510 formed by projecting a part of an opposed surface 51 toward center electrode 4, and a concave part 520 formed toward the opposed surface 51 from the earth electrode's back surface 52. The convex part 510 is disposed so that the extension of a shaft center of the convex part 510 passes through the area in which the concave part 520 is formed. The relation S1>=s is realized when an area of an opening of the concave part 520 is set to S1 and an average cross-section area of a cross section of the convex part 510 perpendicular to an axial direction of the spark plug is set to s.