Abstract: A glow plug includes a housing having an axial hole extending in an axial line direction; a ceramic heater that is relatively displaceable with respect to the housing along the axial line direction and has at least outer surface made of ceramic; and a pressure sensor fixed to the housing and configured to output a signal based on the relative displacement of the ceramic heater. A fixed member fixed to the ceramic heater while the ceramic heater is arranged to an inner circumference of the fixed member. A welded member is welded to an outer circumference of the fixed member. An inner circumferential surface of a portion of the fixed member to which at least the welded member is welded is spaced apart from the outer surface of the ceramic heater.

Abstract: A glow plug including a heater (200) having a rear heat-generating element (260) formed of a resistance heat-generating element, and provided in an axial region thereof between a forward end (136) of a housing and a rear end (315) of a displacement member (300) located rearward of the forward end (136). The heat-generating element (260) is arranged separately from a forward heat-generating element (205) provided at a forward end portion of the heater.

Abstract: A variable member is connected to a rod-shaped member and connected to a tube portion to ensure airtightness within a housing, and deforms when the rod-shaped member is displaced relative to the housing along an axial direction. A position of the connection between the tube portion and the variable member in the axial direction is a position shifted from a rear end of a gap toward a front side by a predetermined length or a position at the front side with respect to the position shifted by the predetermined length. The predetermined length is a length which is 50% of a length of the gap in the axial direction.

Abstract: A glow plug includes a cylindrical housing, a rod-shaped heater, a membrane portion, and a pressure sensor. The cylindrical housing extends along an axial direction. The rod-shaped heater extending along the axial direction is displaced along the axial direction and has one end portion disposed within the housing, and an other end portion which is exposed from the housing. The membrane portion connects together the heater and the housing and has a multi-layer construction which has a first layer and a second layer of which at least part is positioned nearer to the other end portion in the axial direction of the heater than the first layer. The pressure sensor measures a pressure within a combustion chamber in which the other end portion is disposed by making use of a displacement of the heater. A thickness of the second layer is larger than a thickness of the first layer.

Abstract: A ceramic glow plug equipped with a pressure sensor including a ceramic heater, a holding device, a housing sleeve, a housing, a movable member and a pressure sensor. A heat-generating main portion P whose resistance is 75% of the total resistance of the ceramic heater is located forward of the forward end of the holding sleeve.

Abstract: A glow plug includes a housing having an axial hole extending in an axial line direction; a ceramic heater that is relatively displaceable with respect to the housing along the axial line direction and has at least outer surface made of ceramic; and a pressure sensor fixed to the housing and configured to output a signal based on the relative displacement of the ceramic heater. A fixed member fixed to the ceramic heater while the ceramic heater is arranged to an inner circumference of the fixed member. A welded member is welded to an outer circumference of the fixed member. An inner circumferential surface of a portion of the fixed member to which at least the welded member is welded is spaced apart from the outer surface of the ceramic heater.

Abstract: A variable member is connected to a rod-shaped member and connected to a tube portion to ensure airtightness within a housing, and deforms when the rod-shaped member is displaced relative to the housing along an axial direction. A position of the connection between the tube portion and the variable member in the axial direction is a position shifted from a rear end of a gap toward a front side by a predetermined length or a position at the front side with respect to the position shifted by the predetermined length. The predetermined length is a length which is 50% of a length of the gap in the axial direction.

Abstract: A glow plug including a heater (200) having a rear heat-generating element (260) formed of a resistance heat-generating element, and provided in an axial region thereof between a forward end (136) of a housing and a rear end (315) of a displacement member (300) located rearward of the forward end (136). The heat-generating element (260) is arranged separately from a forward heat-generating element (205) provided at a forward end portion of the heater.

Abstract: A coupling member (180) of a glow plug (100) includes a first bend (183) and a second bend (184) folded in an axis direction OD and a joint section (185) in a tapered shape configured to connect the first bend with the second bend and reduce the diameter toward a rear end side of a body portion. Accordingly, in a limited space formed between a housing (130) and a heater unit (150), this configuration increases the length of the coupling member (180), compared with a configuration without any bend folded in the axis direction OD. This results in decreasing the spring constant k of the coupling member 180 and suppressing extension of the coupling member 180 in the axis direction due to thermal expansion.

Abstract: A glow plug includes a cylindrical housing, a rod-shaped heater, a membrane portion, and a pressure sensor. The cylindrical housing extends along an axial direction. The rod-shaped heater extending along the axial direction is displaced along the axial direction and has one end portion disposed within the housing, and an other end portion which is exposed from the housing. The membrane portion connects together the heater and the housing and has a multi-layer construction which has a first layer and a second layer of which at least part is positioned nearer to the other end portion in the axial direction of the heater than the first layer. The pressure sensor measures a pressure within a combustion chamber in which the other end portion is disposed by making use of a displacement of the heater. A thickness of the second layer is larger than a thickness of the first layer.

Abstract: A coupling member (180) of a glow plug (100) includes a first bend (183) and a second bend (184) folded in an axis direction OD and a joint section (185) in a tapered shape configured to connect the first bend with the second bend and reduce the diameter toward a rear end side of a body portion. Accordingly, in a limited space formed between a housing (130) and a heater unit (150), this configuration increases the length of the coupling member (180), compared with a configuration without any bend folded in the axis direction OD. This results in decreasing the spring constant k of the coupling member 180 and suppressing extension of the coupling member 180 in the axis direction due to thermal expansion.

Abstract: A ceramic glow plug equipped with a pressure sensor including a ceramic heater, a holding device, a housing sleeve, a housing, a movable member and a pressure sensor. A heat-generating main portion P whose resistance is 75% of the total resistance of the ceramic heater is located forward of the forward end of the holding sleeve.