US 12,322,930 B2
Insulator and spark plug
Yutaka Yokoyama, Nagoya (JP); Toshiki Kon, Nagoya (JP); and Ippei Kato, Nagoya (JP)
Assigned to Niterra Co., Ltd., Nagoya (JP)
Appl. No. 18/575,062
Filed by Niterra Co., Ltd., Nagoya (JP)
PCT Filed Jul. 21, 2022, PCT No. PCT/JP2022/028314
§ 371(c)(1), (2) Date Dec. 28, 2023,
PCT Pub. No. WO2023/008300, PCT Pub. Date Feb. 2, 2023.
Claims priority of application No. 2021-122439 (JP), filed on Jul. 27, 2021.
Prior Publication US 2024/0305070 A1, Sep. 12, 2024
Int. Cl. H01T 13/38 (2006.01); H01T 13/60 (2011.01)
CPC H01T 13/38 (2013.01) [H01T 13/60 (2013.01)] 5 Claims
OG exemplary drawing
 
1. A tubular insulator for a spark plug, wherein
the insulator contains alumina as a primary component, and further contains a secondary component;
the secondary component contains a silicon (Si) component, a magnesium (Mg) component, a barium (Ba) component, a calcium (Ca) component, and a rare earth component; and
the amounts (mass %) of these components as reduced to oxide and relative to the total mass of the secondary component satisfy the following relations (1) to (5):
15.5≤(the amount of the Si component)≤55.1;  (1)
0.6≤(the amount of the Mg component)≤7.4;  (2)
26.7≤(the amount of the Ba component)≤68.5;  (3)
1.1≤(the amount of the Ca component)≤32.4;  (4)
11.4≤(the amount of the rare earth component)≤46.5; and  (5)
wherein the amount (mass %) of the alumina relative to the total mass of the insulator falls within a range of 91.0 mass % to 97.0 mass %.