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US 3,965,879 AGranted
Radio frequency interference suppression apparatus
AssigneeBrunswick Corporation
InventorArthur O. Fitzner
Life of this patent
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AssigneeBrunswick Corporation
InventorArthur O. Fitzner
Estimating the term…
An ignition wiring system having the leads formed as a wire coil about a magnetizable core defines a distributed constant resistive-inductive series impedance. A metal shield is located over the spark plug proper and electrically connected to the engine ground. A flexible shield extension in the form of a coil extends over the lead from beneath the shield. The shield and shield extension introduce distributed capacitance between the special lead and engine ground. The combination of the shield and shield extension with the special lead forms a distributed constant RLC filter which produces RFI suppression. The shield and shield extension confine the electromagnetic radiation emanating from that portion of the lead where the radiation is strongest, thereby enhancing the suppression. The rapid discharge by the spark plug of the stored energy contained in the distributed capacitance increases the spark intensity and promotes more complete combustion.
An ignition connection apparatus for interconnecting of a pulse signal to an igniting means of an internal combustion engine, comprising an ignition lead including a conducting element for carrying of the high voltage pulse signal and having a resistance on the order of 600 ohms per foot, said conducting element being wound on a magnetizable core to form a distributed inductive-resistive series impedance element and constituting the only inductance connected in the system, and a shield element applied over said lead to define a distributed capacitive shunt impedance, said shield is constructed to overlie the igniting means and defining an essentially uninterrupted shield, said shield including an extension in the form of a flexible coil wound about the lead with a plurality of abutting turns.
A spark plug shield apparatus having a chamber for a spark plug adapted to be secured with an engine block and projecting therefrom, said spark plug having a conductive ledge spaced from the engine block, and an L-shaped boot enclosing the major upper portion of the plug and essentially all of the boot, comprising a pair of shield members having overlapping edges and defining a tubular L-shaped jacket adapted to extend over the boot and spark plug, said shield extending beyond the boot to overlie the adjacent lead wire, means interconnecting the shield members to form a continuous uninterrupted shield, and the ends of the two shield members enclosing the spark plug including inwardly projecting lips adapted to approach one another and located beneath said ledge, a compression spring coil member separate from said two-piece shield members and located and adapted to abut the lips of the shield members, said spring coil being compressed between the lips and the engine to establish a firm electrical contact between the lips and said metal base portion of the spark plug in abutting relation with the metal base portion of the spark plug.
Dependencies are inferred from the claim text.