Title:
Spark plug
Document Type and Number:
Japanese Patent JP6309035
Kind Code:
B2
Abstract:
Disclosed is a spark plug capable of preventing electrode wear while ensuring impact resistance. A conductive seal is in contact with a rear end portion of a center electrode. The conductive seal includes a side-surface seal layer brought into contact with the whole of a side surface of the rear end portion of the center electrode and having a thickness of 10 µm or larger in an axis perpendicular direction so that the spark plug ensure can impact resistance. Assuming that a projection area is defined by projecting the center electrode onto an axial hole in the axis perpendicular direction around a center axis of the spark plug, a contact surface of a resistor brought into contact with the axial hole overlaps at last a part of the projection area. At the time of spark discharge, electric charge accumulated in a parasitic capacitance between the conductive seal and a metal shell moves from the overlap of the contact surface and the projection area to the center electrode. As there occurs a voltage drop with the passage of the electric charge through the resistor, the spark plug can prevent electrode wear.
Inventors:
Tsutomu Kobayashi
Application Number:
JP2016027309A
Publication Date:
April 11, 2018
Filing Date:
February 16, 2016
Export Citation:
Assignee:
Nippon Special Ceramics Co., Ltd.
International Classes:
H01T13/20
Domestic Patent References:
| JP201467651A | ||||
| JP201564987A | ||||
| JP5717587A | ||||
| JP58102480A | ||||
| JP11214119A |
Attorney, Agent or Firm:
Hiroki Nakajima