Internal pre-chamber (IPC) ignition device for turbulent jet ignition in reciprocating engines

1. A reciprocating engine system, comprising:

a cylinder;

a piston movable within the cylinder, having a piston head;

a combustion chamber defined within the cylinder between the piston head and a cylinder head; and

an intermittent prechamber, comprising:

a lower prechamber jaw provided on the piston head;

an upper prechamber jaw provided through the cylinder head; and

one or more prechamber nozzles formed in an interface between the upper prechamber jaw and the lower prechamber jaw,

wherein a prechamber volume and a nozzle area are variable and directly related to a position of the piston head within the combustion chamber.

2. The reciprocating engine system of claim 1 , wherein the intermittent prechamber is formed when the piston is in a crank angle window within 30 degrees from a top dead center position.

3. The reciprocating engine system of claim 1 , wherein the prechamber volume comprises a minimum volume at a top dead center position of the piston.

4. The reciprocating engine system of claim 1 , wherein the prechamber volume varies between 0.5% and 8% of a clearance volume of the combustion chamber at a top dead center position of the piston.

5. The reciprocating engine system of claim 1 , wherein a shape of the one or more prechamber nozzles is continuously variable with the prechamber volume.

6. The reciprocating engine system of claim 1 , further comprising a direct fuel injector mounted in the cylinder head, configured to fuel the combustion chamber during a compression stroke of the piston.

7. The reciprocating engine system of claim 1 , wherein the intermittent prechamber further comprises a spark plug.

8. A prechamber formed in an engine, the prechamber comprising:

a lower prechamber jaw provided on a piston head of a piston movable within a cylinder of the engine;

an upper prechamber jaw provided through a cylinder head of the engine,

one or more prechamber nozzles formed in an interface between the upper prechamber jaw and the lower prechamber jaw,

wherein a nozzle area and a prechamber volume formed between the upper prechamber jaw and the lower prechamber jaw are variable and directly related to a position of the piston within the cylinder.

9. The prechamber of claim 8 , wherein the prechamber is formed when the piston is in a crank angle window near a top dead center position.

10. The prechamber of claim 8 , wherein the prechamber volume comprises a minimum volume at a top dead center position of the piston.

11. The prechamber of claim 8 , wherein the prechamber volume varies between 0.5% and 8% of a clearance volume of the engine at a top dead center position of the piston.

12. The prechamber of claim 8 , wherein a shape of the one or more prechamber nozzles is continuously variable with the prechamber volume.

13. A method, comprising:

providing a reciprocating engine system, having a combustion chamber, a piston, and an intermittent prechamber,

wherein the intermittent prechamber comprises an upper prechamber jaw provided in a cylinder head of the reciprocating engine system and a lower prechamber jaw provided on a head of the piston;

fueling the combustion chamber and the intermittent prechamber using a direct fuel injector during a compression stroke of the piston;

closing the intermittent prechamber, the closing comprising:

moving the upper prechamber jaw and the lower prechamber jaw together to form one or more variable sized prechamber nozzles in an interface between the upper prechamber jaw and the lower prechamber jaw;

igniting a volume of fuel enclosed within the intermittent prechamber with a spark plug;

moving the piston head away from the upper prechamber jaw through the combustion chamber during an expansion stroke of the piston; and

opening the intermittent prechamber.

14. The method of claim 13 , further comprising cooling the intermittent prechamber during the expansion stroke.

15. The method of claim 13 , wherein moving the upper prechamber jaw and the lower prechamber jaw together comprises partially overlapping the lower prechamber jaw with the upper prechamber jaw.

16. The method of claim 15 , wherein the intermittent prechamber is closed between a first position of the piston and a second position of the piston, wherein the first position occurs 30° before a top dead center position of the piston and wherein the second position occurs 30° after the top dead center position of the piston.

17. The method of claim 13 , further comprising releasing trapped unburned hydrocarbon (UHC) from the intermittent prechamber through the one or more prechamber nozzles during the expansion stroke of the piston to prevent backflow of the trapped UHC into the intermittent prechamber.

18. The method of claim 16 , further comprising varying a volume of the intermittent prechamber and a nozzle area capability of the one or more prechamber nozzles when the intermittent prechamber is in a closed configuration.