Patent ID: 8127741

Claim:
An ignition plug for an internal combustion engine, the ignition plug comprising: a hollow main cell; a central electrode extending downward at a central portion of the main cell; a pair of ground electrodes disposed adjacent to a tip of the central electrode and having an arc form; and a pre-combustion chamber cell coupled to the main cell to cover the pair of ground electrodes, thereby forming a pre-combustion chamber, wherein the ground electrodes are fixed to a wall of the main cell, and tips of the ground electrodes and the central electrode are located below a boundary surface of the main cell and the pre-combustion cell, wherein the pre-combustion chamber cell has a main exhaust nozzle facing the tip of the central electrode and four auxiliary exhaust nozzles surrounding the main exhaust nozzle, and wherein the ground electrodes extend downward from the main cell toward the pre-combustion cell and point to the tip of the central electrode, thereby forming an S-shape, wherein the four auxiliary exhaust nozzles are arranged with an angular interval of about 90 degrees around the main exhaust nozzle, and each of the four auxiliary exhaust nozzles has a diameter of about 1.0 Φ to about 1.4 Φ, when the main exhaust nozzle has a diameter of about 1.2 Φ to about 1.4 Φ, wherein the pre-combustion chamber cell has a diameter of about 14 mm to about 18 mm, and a height of about 6 mm to about 7 mm.