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.

In a combustion pressure sensor, a sensor holder is installed in a housing. The sensor holder has an end contact surface. A load transfer member is installed in the housing. The load transfer member has a contact surface facing the end contact surface of the sensor holder. The contact surface of the load transfer member is in contact with the end contact surface of the sensor holder. One of the contact surface of the load transfer member and the end contact surface of the sensor holder has a concavely curved shape, and the other thereof has a convexly curved shape.

A sensor module having a sensor housing, at least one piezoelectric converter element that is disposed in the sensor housing, and at least one insulating member that is disposed in the sensor housing alongside the converter element. The insulating member has on its outer periphery at least one recess in which a contacting system of the converter element extends. A pressure-measuring glow plug having a sensor module of this kind is also described.

Described is a glow plug having a casing and a ceramic glow pin protruding out of the casing. The glow pin has a tapered end section inside the casing. A metal protective tube protrudes out of the casing and surrounds the glow pin. The protective tube has a widened end section inside the casing. A center electrode is arranged in the casing and electrically connected to the glow pin. The glow plug includes an annular or sleeve-shaped contact element through which the glow pin projects and to which the tapered end section of the glow pin is soldered. The contact element is at least partly surrounded by the widened end section of the protective tube.

Breakage in a short period is suppressed by improving a heat dissipation property.

A glow plug (1) that includes: a heater (11), a tip of which is inserted in a combustion chamber of an internal combustion engine; a cylindrical body (12) that supports abase end of the heater; a housing (14) that supports the cylindrical body in a state where a heating section of the heater is projected; and a pressure sensor (15) that is provided in the housing and detects a pressure in a combustion chamber includes: a pressure introduction chamber (142) that is formed between the pressure sensor and the cylindrical body in the housing; and a communication path (21) that is formed in at least one of the housing and the cylindrical body and communicates between the combustion chamber and the pressure introduction chamber.

A glow plug (100) includes: a housing (130) having a metal shell (110) and a cap unit (120); and a heater unit (150). A coupling member (180) is joined with the housing (130) and is also joined with the heater unit (150) at its edge portion (188), so as to enable the heater unit (150) to move along an axis line O and couple the heater unit (150) with the housing (130). When the edge portion 188 of the coupling member 180 is irradiated with a laser, at least part of the edge portion (188) melted by laser welding fills a gap (50) between the coupling member (180) and the heater unit (150) to form a welded part (210). As a result, even when there is a gap prior to welding, the weld strength between the coupling member (180) and the heater unit (150) can be maintained.

Described is a pressure measuring glow plug with a housing, a glow pin, which projects out of the housing and can be displaced in its longitudinal direction relative to the housing against a restoring force. A sensor acquires the position of the glow pin or a pressure acting on the glow pin, and a center pole is arranged in the housing and electrically connected to the glow pin via a contact spring. This disclosure provides that the contact spring is a U-shaped, bent metal strip, which in a middle section has a reduced width, and broadens from the middle section toward its two ends.

A pressure sensor including a rod-shaped member, a tubular housing, a variable member and a pressure measuring element. The variable member is entirely disposed within the housing, is connected to the housing and the rod-shaped member, and deforms when the rod-shaped member is displaced relative to the housing along an axial direction. The variable member includes a first portion connected to the rod-shaped member, a second portion connected to the housing, and a bent portion which connects the first portion and the second portion to each other and has a bent shape. A portion of the second portion is a pressure receiving portion which displaces the rod-shaped member in the axial direction when receiving a pressure. The pressure receiving portion of the second portion has a substantially uniform thickness, and the thickness of the pressure receiving portion of the second portion is larger than that of the first portion.

A combustion pressure sensor having a tubular housing extending in an axial direction DX, a displacement member disposed within the housing, and a tubular connection member which elastically connects the displacement member to the housing. The combustion pressure sensor has a housing weld W1 that connects the housing and the connection member At least a circumferential portion of the housing weld is a bulge housing weld RW1 which bulges in a radial direction DR.

In a combustion pressure sensor, a sensor holder is installed in a housing. The sensor holder has an end contact surface. A load transfer member is installed in the housing. The load transfer member has a contact surface facing the end contact surface of the sensor holder. The contact surface of the load transfer member is in contact with the end contact surface of the sensor holder. One of the contact surface of the load transfer member and the end contact surface of the sensor holder has a concavely curved shape, and the other thereof has a convexly curved shape.