Controlled spark ignited flame kernel flow
In some aspects, a spark plug includes a spark gap in an enclosure of the spark plug. The spark plug includes a passage in the interior of the enclosure. During operation of the engine, the passage directs flow through the spark gap, primarily away from a combustion chamber end of the enclosure. The passage can direct flow at a velocity of 5 meters/second or greater.
1. An igniter for an engine, comprising:
a central electrode;
a velocity control tube arranged around the central electrode and extending beyond an end of the central electrode toward a combustion chamber end of the spark plug, the velocity control tube comprising a ground electrode;
an enclosure of the igniter containing the central electrode and the velocity control tube;
an ignition location between the central electrode and the ground electrode; and
the velocity control tube defining a passage that includes the ignition location and during operation of the engine receives a flow from outside of the enclosure and directs the flow to the ignition location predominantly away from a combustion chamber end of the enclosure, the velocity control tube adapted to produce a peak flow velocity at the ignition location that is at least 10% of the peak flow velocity of the flow into the enclosure.
2. The igniter of claim 1 , where the igniter is adapted to produce a peak flow velocity at the ignition location of 5 meters/second or greater.
3. The igniter of claim 1 , where the ignition location has a height H and the peak flow velocity is V, and where the igniter is adapted to produce H/V*360*RPM less than or equal to 3 crank angle degrees of the engine.
4. The igniter of claim 3 , where igniter is an M14 to M24 and H is 2.5 mm or larger.
5. The igniter of claim 1 , where the igniter is an M14 to M24 igniter and the passage extends at least 1.0 mm beyond an end of the ignition location toward the combustion chamber end of the enclosure.
6. The igniter of claim 5 , where the passage comprises the ignition location and extends at least 0.1 mm beyond an opposing end of the ignition location away from the combustion chamber end of the enclosure.
7. The igniter of claim 5 , comprising:
a first hole in the combustion chamber end of the enclosure that is oriented to direct flow into the passage; and
a second hole in the combustion chamber end of the enclosure that is oriented to direct flow around an exterior of the passage and to an end of the enclosure opposite the combustion chamber end, and the velocity control tube adapted to produce a peak flow velocity at the ignition location that is at least 10% of the peak flow velocity of the flow into the enclosure from the first hole.
8. The igniter of claim 1 , where the igniter is an M14 to M24 size; and
where the igniter is adapted to reach maximum pressure in the enclosure due to combustion of air/fuel mixture in 7 or more crank angle degrees of the engine after a spark in the ignition location.
9. The igniter of claim 1 , comprising:
a metallic shell;
an electric insulator in the shell;
the central electrode extending from the insulator; and
one or more ground electrodes defining the ignition location with the central electrode and one or more ground electrodes defining the passage.
10. The igniter of claim 9 , where more than one ground electrodes define the passage and the ground electrodes do not meet.
11. The igniter of claim 9 , where the one or more ground electrodes comprises a tube defining the passage and comprising an arm extending from the tube, away from the combustion end of the enclosure, to the shell.
12. The igniter of claim 9 , where the central electrode is polygonal in axial cross-section.
13. The igniter of claim 12 , where the one or more ground electrodes define the passage as the same shape in axial cross-section as the central electrode.
14. A method of facilitating combustion in operation of an engine, comprising:
receiving air/fuel mixture from a combustion chamber of the engine into an enclosure of an igniter;
directing the received air/fuel mixture into a passage of a velocity control tube comprising an ignition location, the passage directing the air/fuel mixture predominantly away from a combustion chamber end of the enclosure at a peak flow velocity in the ignition location at least 10% of the peak flow velocity into the enclosure;
igniting the air/fuel mixture in the ignition location; and
the passage directing the ignited air/fuel mixture predominantly away from a combustion chamber end of the enclosure.
15. The method of claim 14 , where the peak flow velocity is 5 meters/second or greater and purges residual gasses from the gap.
16. The method of claim 14 , where the ignition location has a height H of 2.5 mm or larger and the peak flow velocity in the gap is V, and where H/V*360*RPM is less than or equal to 3 crank angle degrees of the engine.
17. The method of claim 14 , comprising directing air/fuel mixture in a swirling flow around an interior of the enclosure and to an end of the enclosure opposite the combustion chamber end; and
shielding the air/fuel mixture igniting at the ignition location from the swirling flow.
18. The method of claim 17 , comprising shielding the ignited air/fuel mixture exiting the ignition location from the swirling flow.
19. The method of claim 14 , where the igniter is an M14 to M24 size and comprising delaying maximum pressure in the enclosure due to combustion of the air/fuel mixture for 7 or more crank angle degrees of the engine after igniting the air/fuel mixture at the ignition location.
20. The method of claim 14 , comprising jetting ignited air/fuel mixture from inside the enclosure into a combustion chamber of the engine only after igniting substantially all of the air/fuel mixture in a half of the enclosure opposite the combustion chamber end.