Laser ignition device

Abstract

In a laser ignition device which is mounted in an internal combustion engine and at least includes a laser spark plug equipped with an optical window which protects an optical device from high temperature and high pressure generated in a combustion chamber and a prechamber cap equipped with a cylindrical prechamber, a prechamber throat portion that is a bottomed cylinder with a sectional area smaller than that of the prechamber, and a plurality of prechamber spray holes which communicate with a combustion chamber on a side of a closed end of the prechamber throat portion, the prechamber cap is arranged between the optical window and the combustion chamber. A converging point FP is located inside the prechamber to ignite an air-fuel mixture delivered into the prechamber, thereby jetting combustion flames from the prechamber into the combustion chamber to fire the internal combustion engine. The center axis AXof the prechamber is oriented horizontally eccentrically from the center axis AXof the prechamber throat portion.