Abstract: An ignition coil, spark plug, and pressure sensor for an internal combustion engine are, in a preferred embodiment, integrated into a single assembly and mounted directly on a plug hole of an internal combustion engine. A hard spark plug shell serves as a pressure member and on which a strain gage is affixed. Changes in the pressure in the combustion chamber deform the shell, causing a corresponding change in the resistance of the strain gage. A bridge circuit or the like is used to measure the resistance change thereby providing a direct indication of cylinder pressure.

Abstract: An improved system for measuring spark plug suppressor resistance under simulating operating conditions includes a controller, a high voltage power supply, a mounting fixture, and a non-contact IR temperature detector. The controller commands the high voltage power supply to source a preselected level of current through the spark plug having a magnitude consistent with actual spark currents. The current sourcing establishes a self-heating arrangement, and the heightened spark plug temperatures and associated resistance simulate actual engine operating conditions. The controller outputs a display of measured resistance values as a function of time, and overlays a trace of the corresponding temperature values.

Abstract: An ignition coil, spark plug, and pressure sensor for an internal combustion engine are, in a preferred embodiment, integrated into a single assembly and mounted directly on a plug hole of an internal combustion engine. A hard spark plug shell serves as a pressure member and on which a strain gage is affixed. Changes in the pressure in the combustion chamber deform the shell, causing a corresponding change in the resistance of the strain gage. A bridge circuit or the like is used to measure the resistance change thereby providing a direct indication of cylinder pressure.

Abstract: An ignition coil, spark plug, and pressure sensor for an internal combustion engine are integrated into a single assembly and mounted directly on a plug hole of an internal combustion engine. A hard spark plug shell serves as a magnetostrictive section for pressure detection. A radially polarized biasing magnet is disposed adjacent the spark plug shell thereby generating an initial flux through a sensing winding. The sensing winding is wound about the lower end of the coil case to sense changes in the induction characteristics of the spark plug shell as a result of pressure changes in the cylinder. A first passive method of sensing pressure whereby the flux change due to the permeability change generates a signal voltage in the sensed coil. This voltage is proportional to the time rate of change of pressure which is integrated to produce a cylinder pressure waveform.