Patent ID: 6668632
Filing Date: 2003-12-30
Classification: G01L

Abstract:
A spark generating assembly configured to detect a pressure in a cylinder of an internal combustion engine, said assembly comprising:a central electrode having a main axis and a first end configured for connection to a voltage source, said central electrode further having a second, exposed end opposite said first end; an annular insulator outwardly of said central electrode, said insulator having an enlarged central body with a first annular shoulder and a second annular shoulder, wherein said insulator includes a third annular shoulder axially intermediate said first and second shoulders; an annular conductive shell having a central bore, said insulator being disposed in said central bore, said shell extending circumferentially and radially inwardly over said first annular shoulder of said insulator to form a first seal having a first spring rate, said shell further having an annular inner shoulder facing said central bore; a second seal having a second spring rate less than said first spring rate disposed between said second annular shoulder of said insulator and said inner shoulder of said shell, wherein said second seal comprises a Belleville washer arranged in a preloaded condition so as to exhibit said second spring rate, said washer having said second spring rate of about zero at a preselected preload force wherein further increases in said pressure in said cylinder above said preselected preload force will encounter reduced stiffness at said lower seal; a ground electrode spaced apart from said second end of said central electrode defining a spark gap therebetween, said ground electrode being electrically connected to said shell; and a transducer affixed to said shell.