Spark plug construction

Claim 1

In a spark plug construction of a type for use in a cylinder of an internal combustion engine and adapted to form and a portion of a spark generating circuit defined between first and second voltage levels, first, second and third substantially coaxially disposed spaced electrodes forming first and second gaps, respectively, between said first and second and said second and third electrodes, said first electrode being adapted to be connected to the first voltage level and said third electrode being adapted to be connected to the second voltage level to form a predetermined potential between said first and third electrodes adapted to apply pulses thereof between said first and third electrodes for forming sparks in the gaps between said first and second and between said second and third electrodes, said electrodes and gaps defining capacitance of measurable time charging value disposed in series between said fit first and third electrodes, and a resistance element in parallel with the capacitance defined between two adjacent ones and said electrodes, said resistance element having a sufficiently high value to cause a spark to occur in the second gap when said potential is coupled between said first and third electrodes, and further serving to discharge the last named capacitance between successive pulses applied between said first and third electrodes so as to lower the required differential between said levels for forming a spark in said gaps.