| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a spark plug having excellent load life performance even when a resistor is heated and formed under the condition that there is some variation in heating temperature. <P>SOLUTION: A spark plug 1 includes: an insulator 2 having a shaft hole 4 penetrating in the direction of an axis line CL1; a center electrode 5 inserted on the tip side of the shaft hole 4, a terminal electrode 6 inserted on the rear end side of the shaft hole 4, and a resistor 7 including at least a conductive material and glass in the shaft hole 4 and arranged between the center electrode 5 and the terminal electrode 6. The resistor 7 includes 15.0 mass% or more of SiO<SP POS="POST">2</SP>, 17.8 mass% or more to 44.8 mass% or less of B<SB POS="POST">2</SB>O<SB POS="POST">3</SB>, 1.2 mass% or more to 6.3 mass% or less of Li<SB POS="POST">2</SB>O, and 3.5 mass% or more to 19.9 mass% or less of BaO. The mass ratio of B<SB POS="POST">2</SB>O<SB POS="POST">3</SB>to the total amount of Li<SB POS="POST">2</SB>O and BaO is 1.43 or more and the mass ratio of Li<SB POS="POST">2</SB>O to BaO is 0.22 or more. <P>COPYRIGHT: (C)2012,JPO&INPIT |
