Ceramic sheathed element glow plug

A sheathed-type glow plug, comprising:

• a ceramic heating element having a ceramic, electrically conductive conducting layer and a ceramic insulating layer, the conducting layer made of lead layers connected by a heating layer, the heating layer having a specific electrical resistance as a function of a temperature within an operating range of the sheath-type glow plug, the specific electrical resistance of the heating layer being greater than a specific electrical resistance of the lead layers and less than a specific electrical resistance of the insulating layer,
• wherein the specific electrical resistance at a room temperature and a temperature coefficient of the lead layers is less than the specific electrical resistance at the room temperature and a temperature coefficient of the heating layer.

A sheathed-type glow plug, comprising:

• a ceramic heating element having a ceramic, electrically conductive conducting layer and a ceramic insulating layer, the conducting layer made of lead layers connected by a heating layer, the heating layer having a specific electrical resistance as a function of a temperature within an operating range of the sheath-type glow plug, the specific electrical resistance of the heating layer being greater than a specific electrical resistance of the lead layers and less than a specific electrical resistance of the insulating layer;
• wherein the specific electrical resistance of the heating layer at a room temperature is at least 10 times greater than a larger of specific electrical resistances of the lead layers at the room temperature.

A sheathed-type glow plug, comprising:

• a ceramic heating element having a ceramic, electrically conductive conducting layer and a ceramic insulating layer, the conducting layer made of lead layers connected by a heating layer, the heating layer having a specific electrical resistance as a function of a temperature within an operating range of the sheath-type glow plug, the specific electrical resistance of the heating layer being greater than a specific electrical resistance of the lead layers and less than a specific electrical resistance of the insulating layer;
• wherein the heating layer is at a tip of the heating element.

A sheathed-type glow plug, comprising:

• a ceramic heating element having a ceramic, electrically conductive conducting layer and a ceramic insulating layer, the conducting layer made of lead layers connected by a heating layer, the heating layer having a specific electrical resistance as a function of a temperature within an operating range of the sheath-type glow plug, the specific electrical resistance of the heating layer being greater than a specific electrical resistance of the lead layers and less than a specific electrical resistance of the insulating layer;
• wherein the heating layer, the lead layers, and the insulating layer are made of ceramic composite structures, which are obtainable from a plurality of compounds using one of a one-step and a multi-step sintering process, the plurality of compounds including at least two of A12O3, MoSi2, Si3N4 and YO3.

A sheathed-type glow plug, comprising:

• a ceramic heating element having a ceramic, electrically conductive conducting layer and a ceramic insulating layer, the conducting layer made of lead layers connected by a heating layer, the heating layer having a specific electrical resistance as a function of a temperature within an operating range of the sheath-type glow plug, the specific electrical resistance of the heating layer being greater than a specific electrical resistance of the lead layers and less than a specific electrical resistance of the insulating layer;
• wherein the heating layer, the lead layers, and the insulating layer are made of a composite precursor ceramic having a matrix material including at least one of polysiloxanes, polysilsesquioxanes, polysilanes, and polysilazanes, which were produced by pyrolysis, the composite precursor ceramic including a filler formed from at least one of A12O3, MoSi2, and SiC.

A sheathed-type glow plug, comprising:

• a ceramic heating element having a ceramic, electrically conductive conducting layer and a ceramic insulating layer, the conducting layer made of lead layers connected by a heating layer, the heating layer having a specific electrical resistance as a function of a temperature within an operating range of the sheath-type glow plug, the specific electrical resistance of the heating layer being greater than a specific electrical resistance of the lead layers and less than a specific electrical resistance of the insulating layer;
• wherein a temperature value of the heating layer is determined using the specific electrical resistance of the heating layer.