System and method for testing breakdown voltage/dielectric strength of spark plug insulators

1. A system for testing an insulative material for a spark plug, comprising:

a test spark plug having at least a center electrode having a first end and a spaced apart second end and an insulator formed of an insulative material surrounding at least a portion of the center electrode, wherein the insulator has an end that is closed, whereby the closed end of the insulator encloses the second end of the center electrode;

a test engine that simulates combustion conditions, wherein a conventional spark plug is installed in a first ignition port of the test engine and the test spark plug is installed in a second ignition port of the test engine; and

a control system for supplying ignition voltage to the test spark plug and the conventional spark plug.

2. The system of claim 1 , wherein the closed end of the insulator has a thickness of between about 0.02 inches and about 0.2 inches.

3. The system of claim 1 , wherein the ignition voltage supplied to the conventional spark plug is constant and the ignition voltage supplied to the test spark plug is variable.

4. The system of claim 1 , wherein the conventional spark plug is coupled to a first ignition coil and the test spark plug is coupled to a second ignition coil.

5. The system of claim 4 , wherein the control system is configured to fire the test spark plug after the control system fires the conventional spark plug.

6. The system of claim 4 , wherein the control system receives an ignition signal from the conventional spark plug and thereafter causes voltage to be applied to the test spark plug.

7. The system of claim 3 , further including a probe that measures the voltage applied to the test spark plug.

8. The system of claim 1 , wherein the closed end of the insulator is shaped during formation of the insulator and is pressure sealed with a resistor or contact glass prior to or after being assembled with the center electrode.

9. The system of claim 1 , wherein the test spark plug further comprises a metal shell surrounding the insulator.

10. The system of claim 9 , wherein the insulator is pressure sealed with a resistor or contact glass prior to or after being assembled with the metal shell.

11. A method of testing an insulative material for a spark plug, the method comprising the steps of:

providing a test spark plug having at least a center electrode and an insulator comprised of an insulative material surrounding at least a portion of the center electrode, wherein the insulator has an end that is closed, whereby the closed end of the insulator encloses an end of the center electrode;

providing a conventional spark plug;

providing a test engine that accepts both the test spark plug and the conventional spark plug;

installing the test spark plug and the conventional spark plug into the test engine;

firing the conventional spark plug to run the engine;

increasing the voltage supplied to the test spark plug until a puncture through the insulative material occurs and recording the voltages supplied to the test spark plug; and

determining when the voltage supplied to the test spark plug decreases after a series of increases to determine the strength of the insulative material.

12. The method of claim 11 , wherein the first ignition port is adjacent an exhaust valve and the second ignition port is adjacent an intake valve.

13. The method of claim 11 , further including the step of running the test engine with a selected set of conditions for between about 15 and about 30 minutes.

14. The method of claim 13 , wherein the selected set of conditions comprises at least:

from about 800 to about 4000 rotations per minute; and

from about 20% to about 100% open throttle.

15. The method of claim 13 , wherein a selected condition is approximately 2500 rotations per minute for the test engine.

16. The method of claim 13 , wherein the selected condition is approximately 30% open throttle.

17. The method of claim 13 , wherein the selected condition is an estimated insulator tip temperature of about 530 degrees Celsius.