Abstract: A spark plug coil assembly has a primary core bearing primary windings and a secondary winding spool around which secondary windings are wound and in which the primary core is received. A case receives the spool with core. The entire case can be made of composite Iron to function as a magnetic return path for the core, or a composite Iron shield can be overmolded to an otherwise plastic case.

Abstract: An ignition apparatus includes a cylindrical core made from magnetically-permeable material and a C-shaped magnetic return path structure that is made from a stack of silicon steel laminations. A tightly controlled air gap is provided between one leg of the C-shaped structure and an end face of the core, forming a magnetic circuit having a high magnetic permeability, which overall reduces the number of primary winding turns needed, thereby reducing the amount of copper wire. In addition, the circular cross-section of the core reduces the mean length per turn (MLT) of the primary winding because the primary winding can be wound directly on the core, which in turn also reduces the MLT of the secondary winding. The reduced MLT also reduces the amount of copper wire. The structure may be replaced using a magnetically-permeable, U-shaped shield.

Abstract: An ignition apparatus includes a transformer having a central core, a primary winding disposed thereabout, a secondary winding disposed outwardly of the primary winding, a case configured to house the central components, and an outer core or shield disposed outwardly of the secondary winding. The central core is formed from multiple, low carbon steel wires held together is a cylindrical shape with cured bond coating material such as an epoxy material or an aromatic polyamide material. In one configuration, at least two different sizes of wires are used in forming the core to increase the density of the magnetically-permeable wire material in the core.

Abstract: A spark plug coil assembly has a primary core bearing primary windings and a secondary winding spool around which secondary windings are wound and in which the primary core is received. A case receives the spool with core. The entire case can be made of composite Iron to function as a magnetic return path for the core, or a composite Iron shield can be overmolded to an otherwise plastic case.

Abstract: An ignition apparatus includes a cylindrical core made from magnetically-permeable material and a C-shaped magnetic return path structure that is made from a stack of silicon steel laminations. A tightly controlled air gap is provided between one leg of the C-shaped structure and an end face of the core, forming a magnetic circuit having a high magnetic permeability, which overall reduces the number of primary winding turns needed, thereby reducing the amount of copper wire. In addition, the circular cross-section of the core reduces the mean length per turn (MLT) of the primary winding because the primary winding can be wound directly on the core, which in turn also reduces the MLT of the secondary winding. The reduced MLT also reduces the amount of copper wire. The structure may be replaced using a magnetically-permeable, U-shaped shield.

Abstract: An ignition apparatus includes a transformer having a central core, a primary winding disposed thereabout, a secondary winding disposed outwardly of the primary winding, a case configured to house the central components, and an outer core or shield disposed outwardly of the secondary winding. The central core is formed from multiple, low carbon steel wires held together is a cylindrical shape with cured bond coating material such as an epoxy material or an aromatic polyamide material. In one configuration, at least two different sizes of wires are used in forming the core to increase the density of the magnetically-permeable wire material in the core.