Patent ID: 6979801
Filing Date: 2005-12-27
Classification: F02P,F23Q,G01L

Abstract:
1. A glow plug for an internal combustion engine, comprising: a cylindrical housing having front and rear housing end portions, an inward protrusion protruding radially inwardly from the rear housing end portion, a threaded portion formed between the front and rear housing end portions for screwing the glow plug in a plug hole of the engine and a sealing portion formed on a front side of the threaded portion for engaging the housing with a given portion of the plug hole to form an airtight seal between the housing and the plug hole; a sheath having a front sheath end portion projecting from the housing and a rear sheath end portion airtightly fixed in the front housing end portion; a heater disposed in the sheath and generating heat upon energization thereof; a center electrode disposed in the housing and having a front electrode end portion, a rear electrode end portion projecting from the housing and an outward protrusion fixed to the center electrode or integral with the center electrode so as to protrude radially outwardly at a location between the front and rear electrode end portions, the center electrode being electronically connected at the front electrode end portion with the heater and mechanically connected with the sheath; and a combustion pressure sensor having a pressure-sensitive element held between a front surface of the inward protrusion and a rear surface of the outward protrusion to generate an electrical signal in response to variations in stress applied thereto.