Enhanced flame ignition for hydrocarbon fuels

In an ignition system for an internal combustion device having a combustion chamber with spark plug means mounted on a mounting structure with an interior surface with a ground firing edge or ground electrode defined as the region between and including the spark plug means outer second electrode or shell end and said interior surface region adjacent said shell end, a central firing end or nose comprising a partially insulated end section of the central electrode of said spark plug means further comprising a ceramic nose with a metallic firing tip or button set at its end forming a coaxial gap with said firing edge, sparking means provided by said spark plug means for igniting an air-fuel mixture in said combustion chamber,

• means for delivering electrical energy to said sparking means to ignite said mixture, said sparking means producing per ignition firing one or more spark pulse discharges and electrical fields upon application of said electrical energy to said spark plug means to ignite the toroidal volume defined by said coaxial gap,
• the improvement comprising:
• a shaping and disposing of said firing end and firing edge such that they form an essentially electric field or electrostatic focussing lens, or EFFL, for focussing the electric field onto or near said firing edge, said coaxial gap between said button and said ground electrode being greater than 0.06", said EFFL feature of said plug means substantially reducing the voltage required to electrically break down the coaxial gap to form spark discharges relative to an equal gap formed between infinite coaxial uniform cylinders.

In a spark ignition combustion system for igniting and combusting a hydrocarbon fuel-air mixture, the combination comprising:

• (a) means for initiating and maintaining spark ignited combustion in repetitive cycles in a compression/expansion combustion volume and for feeding a hydrocarbon fuel-air mixture of high flame-front plasma density thereto, each such cycle comprising a spark ignition period comprising an initial and follow-on ignition stage wherein combustion is initiated,
• (b) spark ignition means for creating an initial spark/flame kernel during the initial spark ignition period which includes an initial breakdown spark of said ignition means, and for producing from said kernel during the follow-on stages of operation of said spark ignition means at least one outwardly moving flame front into said volume and an electric field capable of sustaining a plasma discharge in said outwardly moving flame front,
• said system constructed and arranged such that said outwardly moving flame front propagates into the fuel-air mixture during the follow-on ignition stage such that under normal operation of said combustion system said electric field is sufficiently parallel to said outwardly moving flame front, and the plasma density at the flame front of said moving flame is sufficiently high such that an increasing fraction of the electrical energy available in the follow-on ignition stage is coupled to said moving flame relative to that which is coupled to the spark remnant of said initial kernel, to thus enhance the combustion reactions of said outwardly moving flame fronts of lean hydrocarbon fuel-air mixtures and of otherwise difficult to ignite hydrocarbon fuel-air mixtures.