公开(公告)号：US20190214791A1

公开(公告)日：2019-07-11

申请号：US16088954

申请日：2017-03-17

Applicant: DENSO CORPORATION

Inventor： Yuji KAJI ,  Koji YAMANAKA

IPC: H01T13/20

Abstract: A spark plug for an internal combustion engine that can improve bonding strength between a center electrode and a conductive glass is provided. The spark plug includes a housing, an insulator, a center electrode, a ground electrode, and a conductive glass. The center electrode has a locking portion that is locked from a base end side to a step portion formed on an inner peripheral surface of the insulator, and an electrode head that is closer to the base end side than the locking portion is. A concave portion is partially formed on the tip end surface of the electrode head. A concave contour, which is an outer peripheral contour of the concave portion when viewed in a plug axial direction, forms a closed curve which is spaced apart from a head contour, which is an outer peripheral contour of the base end surface of the electrode head, and surrounds a center axis (B) of the center electrode. The concave contour has an outward portion protruding toward the head contour and an inward portion protruding toward the center axis (B) of the center electrode.

公开(公告)号：US20170288373A1

公开(公告)日：2017-10-05

申请号：US15472673

申请日：2017-03-29

Applicant: DENSO CORPORATION

Inventor： Kenichi ARAYA ,  Koji YAMANAKA ,  Ken HANASHI

IPC: H01T13/39 ,  H01T21/02 ,  H01T13/32

CPC classification number: H01T13/39 ,  H01T13/32 ,  H01T21/02

Abstract: A spark plug has an elongated center electrode, ground electrode, convex part and noble metal coating layer. The center electrode is held in a housing. The ground electrode has a tip end opposing part opposing the center electrode. The convex part is extended from the tip end opposing part to an opposing part face in an axial direction of the spark plug. A spark discharge gap is formed between a tip end part of the center electrode and the convex part. The noble metal coating layer covers a surface of the convex part. The noble metal coating layer has an end face coating layer covering a projecting end face of the convex part and a side face coating layer covering at least a part of a side face of the convex part extended from the projecting end face. A root part of the side face coating layer is buried in the tip end opposing part. An extension is formed so that at least a part of the root part is extended to an outside of the spark plug along the opposing part face.