Dual electrode high thread spark plug

A spark plug located in a generally cylindrical spark plug receiving bore in an internal combustion engine, the bore communicating with a combustion chamber of the internal combustion engine and including a threaded portion, a seat portion which is located closer to the combustion chamber than the threaded portion, and a smaller diameter portion, the spark plug comprising;

• a center electrode having a cylindrical body with a tip at one end and a terminal near the other end;
• an insulator radially surrounding the center electrode and having a substantially cylindrical body;
• a ground shield surrounding said insulator including near one end a ground electrode aligned with the center electrode tip and defining therewith a spark gap and near the other end a threaded portion having threads that are matched with the bore threads;
• and,
• said ground shield having a portion between the threaded portion and the ground electrode which provides a seal between said ground shield and the seat portion of the bore to establish an electrical ground between said ground shield and the engine while at the same time sealing the combustion chamber from the surrounding environment.

A spark plug comprising:

• a pair of elongated center electrodes;
• an insulator disposed radially around said pair of elongated center electrodes having a first diameter section separated by a first shoulder from a second diameter section and a third diameter section separated by a second shoulder from the second diameter section with the second diameter section located intermediate the first and third diameter sections and the diameter of the second diameter section being greater than the diameters of the first and third diameter sections;
• a cylindrical ground shield, having two ground electrodes on one end and a flange on the other end, disposed around the first diameter section with the flange engaging the first shoulder;
• and,
• a cylindrical retainer disposed around the third diameter section and the second diameter section including an internal portion which engages the second shoulder and an end portion which engages said cylindrical ground shield near the first shoulder to capture said insulator therebetween.

A spark plug located in a generally cylindrical opening communicating with a combustion chamber of an internal combustion engine, the opening including a threaded portion and a seat portion located toward the combustion chamber with respect to the threaded portion, the spark plug comprising;

• a pair of center electrodes each having a cylindrical body with a tip at one end and a terminal near the other end;
• an insulator radially surrounding the center electrodes and having a substantially cylindrical body with at least first and second diameter sections separated by a shoulder;
• a ground shield surrounding said insulator first diameter section and including near one end a section juxtaposed with the insulator shoulder and a pair of ground electrodes near the other end each having a portion thereof aligned with one of the center electrode tips to define therewith a spark gap;
• and
• an annular retainer surrounding said insulator second diameter section and including a threaded end for engaging the threaded portion of the generally cylindrical opening and the other end overlapping the ground shield section and juxtaposed insulator shoulder for securing the ground shield and retainer together with the insulator captured therebetween.

A spark plug located in a generally cylindrical spark plug receiving bore in an internal combustion engine, the bore communicating with a combustion chamber of the internal combustion engine and including a threaded portion and a seat portion, the spark plug comprising;

• a pair of electrode each having a cylindrical body with a tip at one end and a terminal near the other end;
• an insulator radially surrounding the center electrodes and having a substantially cylindrical body with at least first and second diameter sections separated by a shoulder;
• a ground shield surrounding said insulator first diameter section and including near one end a section located proximate the insulator shoulder and a pair of ground electrode extending from the other end each having a portion thereof aligned with one of the center electrode tips to define therewith a spark gap;
• and
• an annular retainer surrounding said insulator second diameter section and including a portion having threads that are matched with the bore threads, the annular retainer providing a seal between the ground shield and the seat portion of the bore to establish an electrical ground between the shield and the engine while at the same time sealing the combustion chamber from the surrounding environment.