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.

Based on respective signals from the combustion pressure sensor and a crank angle sensor, heat generation amount data in which a heat generation amount and a crank angle are related to each other is generated, and an estimated heat generation amount is calculated based on a fuel amount in the combustion cycle. When a final value of a heat generation amount in the combustion cycle is smaller than the estimated heat generation amount, the combustion state parameter is calculated based on the heat generation amount data to a crank angle corresponding to the final value of the heat generation amount. When the final value of the heat generation amount is equal to or larger than the estimated heat generation amount, the combustion state parameter is calculated based on the heat generation amount data to a crank angle at which the heat generation amount reaches the estimated heat generation amount.

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.

A pressure-measuring glow plug device includes a module housing, a glow plug configured to ignite a combustion mixture in a combustion chamber of an internal combustion engine, and a pressure-measuring device. The pressure-measuring device has a pressure sensor configured to detect the pressure in the combustion chamber. The glow plug is connected to the module housing by a flexurally elastic membrane. The force acting on the glow plug in the combustion chamber is transferred to the pressure sensor, which is supported on a supporting element by a preloading force. The supporting element is fastened rigidly to the module housing by a sensor housing. The glow plug device further includes a separate loading sleeve that is connected at one end to the pressure-transferring piece and at the other end to the supporting element. The loading sleeve is configured to apply the preloading force for the pressure sensor.

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.

Described is a glow plug with a glow pencil that comprises a forward end with a glow tip and a rearward end, a housing in which the rearward end of the glow pencil is arranged and in relation to which the glow pencil is movable in its longitudinal direction, and a bellows that is connected to the housing and the glow pencil. According to this disclosure, it is provided that a forward end of the bellows is attached to the housing and a rearward end of the bellows is attached to the glow pencil.

In an internal combustion engine which includes a combustion pressure sensor incorporated glow plug and sensor nonincorporated glow plugs, a first plug regression line Lp1 and the second plug regression line Lp2 are in such a relation that, at any temperature Tx within the temperature range Tr, a second voltage Vp2x is lower than a first voltage Vp1x; the resistance of a second electricity supply line is greater than the resistance of a first electricity supply line; and a first section regression line and a second section regression line are in such a relation that, at any temperature Tx within the temperature range Tr, an overall voltage deviation |Vc1xVc2x|, which is the absolute value of the difference between a third voltage Vc1x and a fourth voltage Vc2x, is smaller than a first-second plug voltage difference (Vp1xVp2x).

What is described is a method for igniting a fuel/air mixture in a combustion chamber of an engine, wherein a pencil, which is electrically insulated with respect to walls of the combustion chamber and contains a heating resistor, is electrically heated to a temperature of at least 800 C. in the combustion chamber of the engine by applying a heating voltage, and a high voltage of at least 500 V, which is different from the heating voltage, is applied to the pencil and thereby ions are generated in the combustion chamber by field emission of electrons. The invention additionally relates to an ignition system and a glow plug.