| 摘要 |
PROBLEM TO BE SOLVED: To provide a plasma jet plug capable of generating normal spark discharge.SOLUTION: In the plasma jet plug, a length of a first route connecting from a distal end of a small-diameter part of a center electrode to an opening of a cover of an insulator in a shortest distance is defined as G1 (mm), and a length of a second route connecting from the distal end of the small-diameter part of the center electrode to an inner peripheral surface of a shaft hole of the insulator in a shortest distance is defined as G2 (mm). A length of a third route along a surface of the insulator from a contact of the second route and the inner peripheral surface of the shaft hole of the insulator to the opening of the cover of the insulator is defined as E1 (mm), and a length of a fourth route along the surface of the insulator from a point on the inner peripheral surface of the shaft hole of the insulator closest to a distal end of a large-diameter part of the center electrode to the opening of the cover of the insulator is defined as E2 (mm). In such a case, the plasma jet plug meets a conditional expression (1) of G2+E1/3>G1 and a conditional expression (2) of E2/3>G1. |
