公开(公告)号：US09716370B2

公开(公告)日：2017-07-25

申请号：US15168696

申请日：2016-05-31

Applicant: NGK SPARK PLUG CO., LTD.

Inventor： Naofumi Yamamura ,  Kuniyuki Ishii ,  Naoya Onoda ,  Hiroyuki Odo

IPC: H01T13/20 ,  H01J13/32 ,  H01T13/39 ,  H01T13/32 ,  H01T13/16

CPC classification number: H01T13/39 ,  H01T13/16 ,  H01T13/20 ,  H01T13/32

Abstract: A spark plug includes a metal shell, an insulator, a center electrode, and a ground electrode. At least one of the center electrode and the ground electrode includes a projection having a columnar shape. The projection projects toward the other of the center electrode and the ground electrode and forms the discharge gap. A portion of a side surface of the projection has a recess. A melted portion is formed by melting the noble metal tip and an electrode base material. The recess is formed in the melted portion. When D is a depth of the recess from a side surface of the noble metal tip and R is a diameter of the noble metal tip, 0.05 mm≦D≦0.3×R is satisfied.