Spark generating apparatus having strain gage cylinder pressure measurement feature

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.

Description

TECHNICAL FIELD [0001] The present invention relates to a spark generating apparatus with a pressure sensor. BACKGROUND OF THE INVENTION [0002] An ignition coil for an internal combustion engine that is installed directly on an engine and that is directly coupled with spark plugs is known. However, such conventional ignition coils and / or spark plugs do not generally incorporate a pressure sensor and often are large and costly to produce. A pressure sensor mounted on a spark plug is known as disclosed in U.S. Pat. No. 5,672,812 to Meyer. [0003] Meyer discloses a magnetostrictive pressure sensor device attached to a spark plug shell. The disclosed approach, however, requires a magnetized spark plug shell. This increases cost, and subjects the resulting signal to noise due to environmental factors (e.g., magnetic and electrical noise in an automotive environment). [0004] U.S. Pat. No. 6,119,667 to Boyer et al. disclose an integrated spark plug / ignition coil with a pressure sensor for a...

AI Technical Summary

Benefits of technology

[0007] An object of the present invention is to solve one or more of the problems as set forth in the Background. An advantage of an apparatus according to the invention is that it provides a high quality signal indicative of a pressure detected in a combustion chamber of an internal combustion engine. The high quality signal is generated at a comparatively higher value than certain other pressure sensors conventionally used. Conventional pressure sensing arrangements provide reduced signal output under conditions of low cylinder pressure (i.e., idle or deceleration). The present invention provides a high signal to noise ratio under all operating conditions. Another advantage of the present invention involves flexibility of application. That is, a strain gage sensor portion of the present invention may be mounted in a variety of different locations and orientations.

Problems solved by technology

However, such conventional ignition coils and / or spark plugs do not generally incorporate a pressure sensor and often are large and costly to produce.

This increases cost, and subjects the resulting signal to noise due to environmental factors (e.g., magnetic and electrical noise in an automotive environment).

As with the Meyer device, additional components such as a magnet are needed, which increase cost and complexity.

Additionally, piezoelectric devices have been used in a laboratory environment but are not feasible for mass production.

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