Patent ID: 11929594
Assignee: NITERRA CO., LTD.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A spark plug comprising:
a tubular insulator having a frontward facing surface on an outer circumference thereof, and having an axial hole extending along an axial line;
a center electrode disposed in the axial hole of the insulator;
a tubular metal shell having, on an inner circumference thereof, a ledge portion engaging with the frontward facing surface of the insulator;
a ground electrode electrically connected to the metal shell and providing a spark gap between a front end portion of the center electrode and an end portion thereof; and
a cap joined to the metal shell via a melt portion, wherein
the cap covers the front end portion of the center electrode and the end portion of the ground electrode from a front side to form a sub chamber, and has a jet port penetrating from an inner surface to an outer surface thereof,
a gap which extends from the sub chamber to the melt portion is present between a first surface which connects an inner circumferential surface of the metal shell on the front side with respect to the ledge portion and an outer circumferential surface of the metal shell and a second surface, of the cap, which connects the inner surface and the outer surface, and
the gap has an opening which is open in a radial direction with respect to the sub chamber.