Patent ID: 8893545

Claim:
A glow plug having a combustion pressure sensor in which a rodlike heater is disposed in a tubular housing in an axially displaceable manner with its forward end projecting from a forward end of the housing and with a gap retained between an inner circumferential surface of the housing and an outer circumferential surface of the heater and which has a sensor capable of sensing combustion pressure through detection of pressure or displacement generated as a result of the combustion pressure pressing the heater rearward from the forward end of the heater, wherein a holding member in a tubular shape formed in a deformable manner so as to allow the displacement of the heater and externally fitted to the heater so as to hold the heater is disposed in an annular gap between the outer circumferential surface of the heater and an inner circumferential surface of a forward end of the housing or a portion of the housing located toward the forward end of the housing, in such a manner as to partition the annular gap into axially forward and rearward parts, and is joined to the housing and to the heater along a circumferential direction, the glow plug being characterized in that the holding member has a dual-tube structure consisting of an inner tubular holding member and an outer tubular holding member; one tubular holding member is joined, at its rear end portion, to the housing along the circumferential direction, thereby forming a housing-side joint; the other tubular holding member is joined, at its forward end portion, to a forward end portion of the one tubular holding member along the circumferential direction, thereby forming an inter-tubular-holding-member joint; and the other tubular holding member is joined, at its portion located rearward of the inter-tubular-holding-member joint, to the outer circumferential surface of the heater along the circumferential direction, thereby forming a heater-side joint.