Back to results
US 2011/0254429 A1Published application
Plasma jet spark plug
AssigneeNgk Spark Plug Co., Ltd.
InventorsHiroyuki Kameda, Yoshikuni Sato, Daisuke Nakano, Naofumi Yamamura, Daisuke Kasahara
Life of this patent
Estimating the term…
Abstract
A plasma jet spark plug capable of preventing a channeling progress and having excellent heat conduction. The plasma jet spark plug comprised of: a ceramic insulator having a small diameter portion which assumes a linear shape in an axial direction, and a center electrode has an outer diameter increasing in the order of a frontmost portion, a step portion, a front end portion and a body portion.
Claims10
A plasma jet spark plug comprising:
- a cylindrical insulator having an axial bore extending in an axis direction;
- a rod-like center electrode accommodated in the axial bore of the insulator;
- a plate-like ground electrode disposed on a front end of the insulator,
- wherein the center electrode has a body portion, a front end portion that has an outer diameter smaller than that of the body portion and that is located on a front end side with respect to the body portion, and a frontmost portion having an outer diameter smaller than that of the front end portion and located on a front end side with respect to the front end portion,
- wherein a portion of the insulator where the axial bore is formed has:
- an accommodating portion having an inner diameter smaller than the outer diameter of the body portion of the center electrode, said accommodating portion accommodating therein at least the front end portion of the center electrode, and
- a small diameter portion having an inner diameter smaller than the outer diameter of the front end portion of the center electrode and smaller than the inner diameter of the accommodating portion, the small diameter portion located on the front end side with respect to the accommodating portion and accommodating therein at least the frontmost portion of the center electrode,
- wherein the frontmost portion of the center electrode is accommodated in the small diameter portion of the insulator such that a front end of the center electrode is located in the small diameter portion of the insulator toward a rear side such that the front end of the center electrode is spaced from a front end of the insulator wherein the front end of the center electrode forms a cavity with an inner circumference of the small diameter portion of the insulator,
- wherein the ground electrode has an opening for use in communicating the cavity and an outside air, and
- wherein the small diameter portion of the insulator in the axis direction assumes a linear shape.
7 more elements
Dependencies are inferred from the claim text.