Glow plug
AssigneeNgk Spark Plug Co., Ltd.
InventorsTakaya Yoshikawa, Shinya Murakoshi
Life of this patent
Estimating the term…
Abstract
A glow plug comprising: a ceramic heater which houses a heating element defined herein in a tip end side of said ceramic heater, and which elongates in an axial direction; a cylindrical metal shell which has a shaft hole, which houses a rear end portion of said ceramic heater in said shaft hole, and which holds said ceramic heater in said shaft hole directly or via another member; and a center pole including a center-pole rear end portion as defined herein and a center-pole tip end portion as defined herein, said ceramic heater being mechanically rigidly joined to said heater connecting portion, wherein a stress releasing portion in which a diameter is smallest in an area between said heater connecting portion and said center-pole rear end portion is formed in said center pole.
Claims12
A glow plug comprising:
- a ceramic heater including a heating element provided in a tip wend side thereof, said heating element being capable of generating heat upon energization;
- a cylindrical metal shell which has a shaft hole, which houses a rear end portion of said ceramic heater in said shaft hole, and which holds said ceramic heater in said shaft hole directly or via another member;
- and
- a coaxial center pole including:
- a terminal portion provided in a rear end of said center pole, said terminal portion being supplied with electric power from outside directly or via another member;
- a heater connecting portion having a hole provided in a tip end of said center pole, a rear end portion of said ceramic heater being mechanically rigidly fitted into said hole;
- and
- a stress releasing portion having the smallest diameter in an area between said heater connecting portion and said terminal portion.
Dependencies are inferred from the claim text.