A glow plug is described, having a body, a glow pin which protrudes from a first end of the body, and an inner pole which protrudes from a second end of the body and is electrically connected to the glow pin. A section of the inner pole that protrudes out of the body has an embossed structure for improving the mechanical and electrical connection to a plug connector. A method for producing a glow plug is also disclosed.

A method is described for determining the resistance temperature characteristic of a ceramic glow plug, wherein the glow plug is heated at a specified power, wherein before the heating it is first determined whether the glow plug is an aged glow plug, and then, if the glow plug has not been detected as an aged glow plug, the glow plug is heated at a first specified power and the resistance value thereby achieved is assigned to a temperature that is anticipated to be the final temperature when heating a factory-outlet glow plug at this first power, or if the glow plug has been detected as an aged glow plug, the glow plug is heated at a reduced power which is smaller than the first power, and the resistance value achieved thereby is assigned to the same temperature that is also anticipated when heating a factory-outlet glow plug at the first power.

When only smoke is generated, the sensor sensitivity is not substantially changed from the initial value. When both smoke and unburned HC are generated, the number of times the sensor sensitivity becomes lower than the initial value is increased. From these results, it can be understood that a deposit is formed in the presence of unburned HC and smoke existing simultaneously. The degree of reduction in sensor sensitivity becomes higher if the smoke concentration is increased when the unburned HC concentration condition is fixed. From this result, it can also be understood that while the coexistence of smoke and unburned HC is a prerequisite, unburned HC contributes largely to the formation of a deposit.

A glow plug including a substantially cylindrical housing extending in an axial direction; a rod-shaped heater unit having a front end protruding from the front end of the housing and movable in the axial direction; a connecting member connecting the heater unit to the housing within the housing and allowing the heater unit to move in the axial direction; and a pressure sensor that detects pressure received by the heater unit. The heater unit has a large-diameter portion at the rear end thereof and a small-diameter portion frontward of the large-diameter portion and having a diameter smaller than the diameter of the large-diameter portion. The connecting member connects the small-diameter portion of the heater unit to the housing within the housing.

A metal shell of a glow plug mounted on an engine head of a diesel engine and a method of manufacturing the same are disclosed. The metal shell has an improved multi-stage structure, which allows the metal shell to be easily manufactured regardless of overall length of the metal shell and allows a metal shell section fastened to the engine head and at least one of the other metal shell sections to have different material strengths, thereby increasing fastening strength of the metal shell to the engine head and preventing warpage of the metal shell while improving productivity while reducing manufacturing costs. The metal shell of a glow plug for diesel engines according to the invention includes a plurality of metal shell sections disposed in an axial direction of the glow plug and having different material strengths.

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.

A high-voltage ceramic electric heating element, comprising a body (9), the body (9) being hollow and having an open trailing portion, and a notch (7) being provided on the body (9) in the axial direction and extending through from left to right; a temperature control region (8) is provided at a position on an outer resistance layer (2) of the body (9), and the cross sectional area of the temperature control region (8) is smaller than the cross sectional area of the body (9). Using the high-voltage ceramic electric heating element can improve the ignition reliability and the service life.

A glow plug wherein a combustion gas prevention wall (67) extends radially outward on the outer circumferential surface of heater (10) such that when the heater (10) is viewed rearward from its forward end (10a) along the axial direction, the combustion gas prevention wall (67) closes an annular gap K1 at a position forward of annular membrane portion (63) of seal member (60). The combustion gas prevention wall (67) has an outer diameter D2 greater than the inner diameter D1 of forward end (136) of the housing.

A method for regulating or controlling the temperature of a sheathed-element glow plug in a heating phase of the sheathed-element glow plug, where a temperature value is determined as a function of a resistance of the sheathed-element glow plug. To render possible the regulation or control of the temperature of the sheathed-element glow plug also during a transient temperature distribution within the sheathed-element glow plug, the resistance used for determining the temperature value during a transient thermal response within the sheathed-element glow plug is calculated with the aid of a physical model.

Provided is a glow plug assembly having dual terminals formed to enable a fast response and reliable control thereof by preventing noise generation caused by grounding, and the assembly including: a housing; a heating tube; a cap; first and second terminals of which lower parts enter inside the heating tube; and a heating coil of which opposite ends are engaged with the first and the second terminals, and a winding part is placed close to the heating tube, wherein the first terminal is shorter than the second terminal in length and is engaged with the heating coil, and the second terminal extends downward to be longer than the first terminal in length, and has a bent part that leads the second terminal to a center of the wound heating coil to secure an insulation space relative to the heating coil, and is engaged with the heating coil.