Spark plug
AssigneeCaterpillar Inc.
InventorJames Jay Cress
Life of this patent
Estimating the term…
Abstract
A spark plug includes a central electrode member and an outer electrode member. The central electrode member includes a central base and a plurality of electrode prongs extending in an axial direction from the central base. The outer electrode member surrounds the central electrode member. The outer electrode member includes a wall that is radially spaced from the plurality of electrode prongs to allow a series of electric arcs to form between the wall and the plurality of electrode prongs. The outer electrode member and the central electrode member are sized and positioned relative to one another such that a first rate of wear of the outer electrode member, along a longitudinal axis of the spark plug, is substantially equal to a second rate of wear of the central electrode member along the longitudinal axis.
Claims20
A spark plug comprising:
- a housing defining a longitudinal axis, and including an outer surface, an inner surface forming a combustion prechamber, a side wall, and a bottom wall, and a plurality of flow passages from the combustion prechamber each extending through one of the side wall or the bottom wall from the inner surface to the outer surface;
- the housing further including a first protruding segment, a second protruding segment that includes the side wall, and a connecting segment, and the connecting segment is reduced in diameter relative to the first protruding segment and the second protruding segment;
- a first electrode having an electrode surface extending circumferentially around the longitudinal axis;
- a second electrode including a plurality of electrode prongs four or greater in number and spaced from the electrode surface to form a plurality of spark gaps within the combustion prechamber between the first electrode and the second electrode;
- and
- each of the plurality of electrode prongs having a thickness (t) in a radial direction, a width (w) in a circumferential direction, and being spaced from the electrode surface a gap length (l) in the radial direction, and l is greater than at least one of t or w.
A spark plug comprising:
- a housing defining a longitudinal axis, an outer surface, an inner surface forming a combustion prechamber, a side wall, and a bottom wall, and a plurality of flow passages from the prechamber each extending through one of the side wall or the bottom wall from the inner surface to the outer surface;
- the housing further including a first protruding segment having a tool engagement portion, a second protruding segment having a threaded portion, and a connecting segment extending between the first protruding segment and the second protruding segment;
- a first electrode having an electrode surface extending circumferentially around the longitudinal axis;
- a second electrode including a plurality of electrode prongs four or greater in number and spaced from the electrode surface to form a plurality of spark gaps within the combustion prechamber between the first electrode and the second electrode;
- each of the plurality of electrode prongs including a radial portion, and an axial portion extending from a respective one of the radial portions and having a thickness (t) in a radial direction, a width (w) in a circumferential direction, and being spaced from the electrode surface a gap length (l) in the radial direction;
- and
- the plurality of electrode prongs being configured by way of sizes of t, w, and l, such that a first rate of wear of the first electrode is substantially equal to a second rate of wear of the second electrode.
A method comprising:
- energizing a spark plug including a first electrode and a second electrode positioned such that at least one spark gap within a combustion prechamber of the spark plug is defined between the first electrode and the second electrode;
- generating a spark at the spark gap based on the energizing a spark plug;
- wearing the first electrode so as to shorten the first electrode at a first wear rate, based on the energizing a spark plug;
- wearing the second electrode so as to produce a concavity in the second electrode at a second wear rate that is substantially equal to the first wear rate, based on the energizing a spark plug;
- and
- repeating the energizing a spark plug until the first electrode has shortened from an initial length by at least 1.5 millimeters to a reduced length.
Dependencies are inferred from the claim text.