Spark plug insulator having an anti-fouling coating and methods for minimizing fouling
An insulator for a spark plug comprises a first segment surrounding the terminal, a second segment extending from the first segment, and a third segment extending from the second segment. A gap is disposed between the third segment of the insulator and the outer shell. At least one coating having a least one layer is disposed on a surface of the third segment.
1. A spark plug for an internal combustion engine, the spark plug comprising:
an elongated center electrode having a center electrode tip at a first end and a terminal proximate a second end opposite the first end;
an insulator surrounding at least a portion of the center electrode; and
an outer shell surrounding at least a portion of the insulator;
wherein the insulator comprises:
a first segment surrounding at least a portion of the terminal,
a second segment extending from the first segment,
a third segment extending from the second segment, wherein a gap is disposed between the third segment of the insulator and the outer shell such that at least a portion of the third segment of the insulator is exposed to a combustion chamber when the spark plug is disposed within an internal combustion engine, and
a coating applied to at least a portion of the third segment, wherein the coating is formed of a first layer disposed on at least a portion of a surface of the third segment and a second layer disposed on at least a portion of the first layer,
wherein the first layer is formed of a first glaze material and the second layer is formed of a second glaze material, and the first glaze material and the second glaze material are different materials.
2. The spark plug of claim 1 , wherein the first glaze material has a first softening point and the second glaze material has a second softening point and the second softening point is less than the first softening point.
3. The spark plug of claim 1 , wherein a first thickness of the first layer and a second thickness of the second layer are different.
4. The spark plug of claim 1 , wherein the coating extends between an end of the insulator disposed adjacent the center electrode and a point where the outer shell retains the insulator in position.
5. The spark plug of claim 1 , wherein the coating extends along a surface of the insulator and ends at a point that is spaced from the center electrode or a point where the outer shell retains the insulator in position.
6. The spark plug of claim 1 , further including a third layer disposed on at least a portion of the second layer.
7. The spark plug of claim 1 , wherein at least one of the first and second glaze materials includes a refractory powder.
8. The spark plug of claim 7 , wherein the refractory powder is selected from the group consisting of a high temperature ceramic powder, alumina, zirconium oxide (ZrO 2 ), mullite, yittrium oxide (Y 2 O 3 ), magnesium oxide (MgO), lanthium oxide (La 2 O 3 ), boron nitride (BN), aluminum nitride (AlN), and combinations thereof.
9. The spark plug of claim 1 , wherein a gap is formed between the insulator and the center electrode.
10. The spark plug of claim 1 , wherein the third segment of the insulator is tapered from a first end adjacent the second segment toward a second end opposite the second segment such that a thickness of the insulator at the second end is less than a thickness of the insulator at the first end.
11. A spark plug for an internal combustion engine, the spark plug comprising:
an elongated center electrode having a center electrode tip at a first end and a terminal proximate a second end opposite the first end;
an insulator surrounding at least a portion of the center electrode; and
an outer shell surrounding at least a portion of the insulator;
wherein the insulator comprises:
a first segment surrounding the terminal,
a second segment extending from the first segment,
a third segment extending from the second segment, wherein a gap is disposed between the third segment of the insulator and the outer shell such that at least a portion of the third segment of the insulator is exposed to a combustion chamber when the spark plug is disposed within an internal combustion engine, and
a first coating applied to a first portion of the third segment, and
a second coating applied to a second portion of the third segment,
wherein at least a portion of the second coating is disposed between the first coating and the second segment.
12. The spark plug of claim 11 , wherein the first and second coatings abut one another and do not overlap.
13. The spark plug of claim 11 , wherein the first coating is comprised of a first glaze material having a first softening point and the second coating is comprised of a second glaze material having a second softening point that is lower than the first softening point.
14. The spark plug of claim 13 , wherein the first and second glaze materials are different materials.
15. The spark plug of claim 11 , further including a third coating applied to a third portion of the third segment between the second coating and the second segment.
16. The spark plug of claim 11 , wherein the first coating is formed of a first glaze material and the second coating is formed of a second glaze material, wherein at least one of the first and second glaze materials includes a refractory powder.
17. The spark plug of claim 16 , wherein the refractory powder is selected from the group consisting of a high temperature ceramic powder, alumina, zirconium oxide (ZrO 2 ), mullite, yittrium oxide (Y 2 O 3 ), magnesium oxide (MgO), lanthium oxide (La 2 O 3 ), boron nitride (BN), aluminum nitride (AlN), and combinations thereof.
18. An insulator for a spark plug, the insulator comprising:
a first segment surrounding at least a portion of a terminal,
a second segment extending from the first segment,
a third segment extending from the second segment, and
a coating applied to at least a portion of the third segment, wherein the coating is formed of a first layer disposed on at least a portion of a surface of the third segment and a second layer disposed on at least a portion of the first layer,
wherein the first layer is formed of a first glaze material and the second layer is formed of a second glaze material, and the first glaze material and the second glaze material are different materials.
19. The spark plug of claim 18 , wherein the first glaze material has a first softening point and the second glaze material has a second softening point and the second softening point is less than the first softening point.
20. The spark plug of claim 18 , wherein a first thickness of the first layer and a second thickness of the second layer are different.
21. The spark plug of claim 18 , further including a third layer disposed on at least a portion of the second layer.
22. The spark plug of claim 18 , wherein at least one of the first and second glaze materials includes a refractory powder.
23. The spark plug of claim 22 , wherein the refractory powder is selected from the group consisting of a high temperature ceramic powder, alumina, zirconium oxide (ZrO 2 ), mullite, yittrium oxide (Y 2 O 3 ), magnesium oxide (MgO), lanthium oxide (La 2 O 3 ), boron nitride (BN), aluminum nitride (AlN), and combinations thereof.
24. The spark plug of claim 18 , wherein a gap is formed between the insulator and the center electrode.
25. The spark plug of claim 18 , wherein the third segment of the insulator is tapered from a first end adjacent the second segment toward a second end opposite the second segment such that a thickness of the insulator at the second end is less than a thickness of the insulator at the first end.
26. An insulator for a spark plug, the insulator comprising:
a first segment surrounding a terminal,
a second segment extending from the first segment,
a third segment extending from the second segment, and
a first coating applied to a first portion of the third segment, and
a second coating applied to a second portion of the third segment,
wherein at least a portion of the second coating is disposed between the first coating and the second segment.
27. The spark plug of claim 26 , wherein the first and second coatings abut one another and do not overlap.
28. The spark plug of claim 26 , wherein the first coating is comprised of a first glaze material having a first softening point and the second coating is comprised of a second glaze material having a second softening point that is lower than the first softening point.
29. The spark plug of claim 28 , wherein the first and second glaze materials are different materials.
30. The spark plug of claim 26 , further including a third coating applied to a third portion of the third segment between the second coating and the second segment.
31. The spark plug of claim 26 , wherein the first coating is formed of a first glaze material and the second coating is formed of a second glaze material, wherein at least one of the first and second glaze materials includes a refractory powder.
32. The spark plug of claim 31 , wherein the refractory powder is selected from the group consisting of a high temperature ceramic powder, alumina, zirconium oxide (ZrO 2 ), mullite, yittrium oxide (Y 2 O 3 ), magnesium oxide (MgO), lanthium oxide (La 2 O 3 ), boron nitride (BN), aluminum nitride (AlN), and combinations thereof.