Gaseous fuel engine and operating strategy for limiting preignition in prechamber sparkplug

1. A method of operating a gaseous fuel engine system comprising:

spark-igniting a gaseous hydrogen fuel (H2) and air in a prechamber sparkplug fluidly connected to a cylinder in an engine;

igniting a main charge containing H2 and air in the cylinder via the spark-ignited H2 and air in the prechamber sparkplug;

determining a preignition condition of the gaseous fuel engine system;

conveying cooling air through a cooling air conduit to the prechamber sparkplug based on the determining a preignition condition; and

limiting preignition of H2 and air in the prechamber sparkplug based on the conveying cooling air.

2. The method of claim 1 further comprising commanding varying a position of a cooling air valve in the cooling air conduit based on the determining a preignition condition.

3. The method of claim 2 wherein the conveying cooling air further includes conveying cooling air from a compressor in an intake conduit of the gaseous fuel engine system directly into a prechamber in the prechamber sparkplug.

4. The method of claim 2 wherein the conveying cooling air includes conveying the cooling air to the prechamber sparkplug while a gas exchange valve for the cylinder is open.

5. The method of claim 3 further comprising conveying the H2 and air into a prechamber in the prechamber sparkplug via at least one port fluidly connecting the prechamber to the cylinder, during a compression stroke of a piston in the cylinder, and wherein the conveying cooling air includes conveying the cooling air to the prechamber sparkplug during an intake stroke of the piston.

6. The method of claim 1 wherein the conveying cooling air includes increasing a flow of the cooling air relative to a prior engine cycle, and further comprising decreasing a flow of the cooling air in a subsequent engine cycle to modulate a temperature of the prechamber sparkplug.

7. The method of claim 1 wherein the determining a preignition condition includes determining a preignition risk condition based on a stored preignition risk model.

8. The method of claim 7 further comprising populating the stored preignition risk model with a plurality of monitored operating parameters upon the basis of which the preignition risk condition is dependent.

9. The method of claim 8 wherein the main charge includes the H2 and a gaseous hydrocarbon (HC) fuel, and the plurality of operating parameters includes an H2 concentration parameter, at least one of an engine speed parameter or an engine load parameter, and a lambda parameter.

10. An ignition system for a gaseous fuel engine comprising:

a prechamber sparkplug;

a cooling air conduit fluidly connected to the prechamber sparkplug;

a cooling air valve within the cooling air conduit; and

a preignition controller in control communication with the cooling air valve and structured to:

determine a preignition condition of the gaseous fuel engine system;

command an adjustment to a position of the cooling air valve based on the determined preignition condition to vary a flow of cooling air through the cooling air conduit to the prechamber sparkplug; and

limit preignition of a gaseous fuel and air in the prechamber sparkplug based on the varying of the flow of cooling air.

11. The ignition system of claim 10 wherein the prechamber sparkplug includes spark electrodes within a prechamber, and the cooling air conduit opens to the prechamber.

12. The ignition system of claim 10 further comprising a computer readable memory storing a preignition risk model, and the preignition controller is further structured to determine the preignition condition based on the preignition risk model.

13. The ignition system of claim 12 wherein the preignition controller is further structured to populate the preignition risk model with a plurality of engine operating parameters upon which a preignition risk in the gaseous fuel engine system is dependent.

14. The ignition system of claim 13 wherein the plurality of engine operating parameters includes an H2 concentration parameter.

15. The ignition system of claim 14 wherein the plurality of engine operating parameters includes at least one of an engine speed parameter or an engine load parameter, and a lambda parameter.

16. The ignition system of claim 10 wherein the preignition controller is further structured via the varying of the flow of cooling air to increase a flow of the cooling air relative to a prior engine cycle in the gaseous fuel engine system.

17. The ignition system of claim 16 wherein the preignition controller is further structured to:

determine a subsequent preignition condition; and

command a subsequent adjustment to a position of the cooling air valve based on the determined subsequent preignition condition to decrease a flow of cooling air through the cooling air conduit to the prechamber sparkplug.

18. A preignition control system for a gaseous fuel engine system comprising:

a preignition controller structured to:

monitor a plurality of engine operating parameters on the basis of each of which a preignition condition of the gaseous fuel engine system is dependent;

determine a preignition condition of the gaseous fuel engine system based upon the monitored plurality of engine operating parameters; and

command an adjustment to a position of a cooling air valve based on the determined preignition condition, such that a flow of cooling air through a cooling air conduit to a prechamber sparkplug is varied to modulate a temperature of the prechamber sparkplug.

19. The preignition control system of claim 18 further comprising a computer readable memory storing a preignition risk model populated based on the plurality of engine operating parameters.

20. The preignition control system of claim 19 wherein the plurality of engine operating parameters includes an H2 concentration parameter, at least one of an engine speed parameter or an engine load parameter, and a lambda parameter.