Patent ID: 8810115

Claim:
A sparkplug comprising: an induction coil; and a central electrode fixedly connected to the induction coil; the induction coil including, in order from an electrical connection terminal of the sparkplug, a first end portion, a central portion, and a second end portion; the central electrode extending in line with the second end portion and away from the central portion; the induction coil including a conducting wire wound helically while forming a succession of coaxial turns, the second end portion having a terminal turn situated opposite the central portion and connected to the central electrode, the induction coil configured to produce an electrical field induced in the second end portion; wherein the second end portion comprises a plurality of coaxial end turns that extend axially between the terminal turn and an upstream turn situated toward the central portion; and wherein the terminal turn has a diameter smaller than the diameter of the upstream turn, while the turns of the plurality of coaxial end turns have a radius of curvature that reduces progressively between the upstream turn and the terminal turn so as to be able to reduce intensity of the electrical field induced in the second end portion in a vicinity of the terminal turn.