Plasma jet ignition plug and manufacturing method thereof

摘要

[Objective] To reliably prevent current leakage with restraint on variation in the position of a ground electrode relative to an insulator and on overheat of the ground electrode, for stable generation of plasma.

<Paragraphs id="pa02" num="0002" xmlns:base="http://www.sipo.gov.cn/XMLSchema/base">[Means for Solution] A plasma jet ignition plug 1 includes an insulator 2 having an axial bore 4 extending in the direction of an axis CL1, a center electrode 5 inserted in the axial bore 4, a metallic shell 3 disposed externally of the outer circumference of the insulator 2, and a ground electrode 27 fixed to the metallic shell 3, and has a cavity 29 defined by the wall surface of the axial bore 4 and the front end surface of the center electrode 5. Supports 31 to 34 intervene between the insulator 2 and the ground electrode 27. A space formed radially outward of the supports 31 to 34 and a space formed radially inward of the support 31 to 34 communicate with each other. As viewed on an imaginary plane which is orthogonal to the axis CL1 and onto which the opening of the axial bore 4 and the supports 31 to 34 are projected, a point A which is on the outline of each of the supports 31 to 34 such that the distance to the axis CL1 therefrom is the shortest distance between the outline and the axis CL1 is located radially outward of the outline of the opening of the axial bore 4.