Temperature controlled glow plug having controlled saturation and afterglow characteristics

A temperature self-control type glow plug comprising:

• a first helical resistive element serving as a heating element;
• a second helical resistive element connected in series with one end of said first helical resistive element and made of a material having a positive resistance temperature coefficient larger than that of said first helical resistive element;
• a metallic sheath enclosing said first and second helical resistive elements in an end to end relationship, said first and second helical resistive elements embedded in a heat resistant electric insulating powder,
• wherein an outer sheath diameter DR of a portion of said sheath in which said first helical resistive element is embedded is set to be smaller than an outer sheath diameter DB of a portion of said sheath in which said second helical resistive element is embedded,
• a gap larger than the sheath diameter DR of the portion in which said first helical resistive element is embedded formed between ends of said first and second helical resistive elements, and
• said two helical resistive elements connected to each other within the gap through connecting ends respectively extending from said resistive elements,
• said connecting ends located within an outer diameter of said first helical resistive element.