JPS57191466A - Laser igniting apparatus for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve durability and reliability of a laser igniting apparatus, by omitting a laser beam distributing means or other through employment of such an arrangement that a single laser beam produced by a laser oscillator of the laser igniting apparatus is passed through combustion chambers of an internal combustion engine and it is focused in two cylinders by use of convex lenses. CONSTITUTION:A laser pulse emitted to meet with the ignition timing of either one of a plurality of cylinders under the control of a laser pulse generator controlling circuit 2 is passed through the upper end portions of respective combustion chambers and makes focuses F1-F4 at positions near the axis of symmetry in respective combustion chambers by means of convex lenses 4-1-4-4. Here, the energy of laser pulse is so selected that dielectric breakdown is caused at the density of air-fuel mixture at the time when ignition is to be caused. However, since the density of mixture in other cylinders at te time is lower, dielectric breakdown is not caused in said other cylinders by the same level of energy. Thus, it is enabled to supply energy selectively to the cylinder in which ignition is to be caused and to thereby cause ignition and combustion of mixture. Further, laser pulse emitted to meet with the ignition timing of next cylinder causes dielectric breakdown and hence ignition of mixture only in said next cylinder.