Patent ID: 9647428
Date: 2017-05-09
CPC Classifications: H01T

Claim:
1. A spark plug for an internal combustion engine comprising: a tubular housing; a tubular insulator supported inside the housing; a center electrode supported inside the insulator so that a distal end portion, which is a portion inserted into a combustion chamber of the internal combustion engine, of the center electrode protrudes; a ground electrode that forms a spark discharge gap between the ground electrode and the center electrode; a resistor supported inside the insulator at a proximal side, which is a side opposite to the distal end, of the central electrode; and a stem supported inside the insulator at a proximal side of the resistor; wherein, of an outer peripheral surface of the insulator, and closer to a distal end side than a proximal portion of the resistor is, there is formed a high emissivity surface of which thermal emissivity is at least 0.7 on at least a part of a portion facing an inner circumferential surface of the housing.