Patent ID: 9422913
Filing Date: 2016-08-23
CPC Classification: F02P,F23Q,G01L,G01M

Claim Text:
1. A glow plug equipped with a pressure sensor comprising: a ceramic heater extending in an axial direction and having a columnar substrate formed of electrically insulating ceramic, a resistance heat-generating element integrated with the substrate and performing resistance heat generation through application of electricity thereto, and an electrode lead-out portion electrically connected to the resistance heat-generating element and formed at a rear end portion of the resistance heat-generating element in such a manner as to be exposed at an outer surface of the substrate; a holding sleeve made of metal, connected directly or indirectly to the electrode lead-out portion, and holding the ceramic heater while allowing a forward portion of the ceramic heater to protrude therefrom; a housing having a tubular form and accommodating therein the ceramic heater and the holding sleeve; a movable member formed of a metal sheet, joined to the holding sleeve and the housing to airtightly separate a forward side and a rear side thereof, and being elastically deformable in response to combustion pressure; and a pressure sensor disposed rearward of the ceramic heater, the holding sleeve, and the movable member and in the interior of the housing and adapted to detect pressure applied thereto; the glow plug being characterized in that a heat-generating main portion is located forward of the holding sleeve, where the heat-generating main portion is a forward end portion of the ceramic heater which encompasses a forward end of the ceramic heater and whose resistance accounts for 75% of a total resistance of the ceramic heater; the heat-generating main portion is shorter in axial length than a heat-generating sub portion, where the heat-generating sub portion is a portion of the ceramic heater extending further rearward from a rear end of the heat-generating main portion, and the sum of the resistance of the heat-generating sub portion and the resistance of the heat-generating main portion is 80% of the total resistance; and the joint part between the holding sleeve and the movable member is located rearward of the heat-generating sub portion.