Application of capacitance-to-digital converter to investigate dielectric properties of spark plugs insulators

The majority of today's road vehicles are powered with spark ignition combustion engines. Spark plugs are required then to ignite air - fuel mixture within engines fueled with gasoline. The efficiency of the combustion process and spark ignition engines fuel economy depend significantly on ignition circuit providing high voltage to discharge a spark between the electrodes of a spark plug. Hence, spark plugs parameters, their quality and condition are of importance. This paper describes a novel method of spark plug testing based on the low capacitance measurement using a sigma-delta capacitance-to-digital converter. Theoretical spark plug capacitance analysis, some results of spark plugs capacitance measurement and ceramic insulator dielectric constant calculation are presented and discussed.