Pre-chamber ignition system
Methods and systems are provided for purging a pre-chamber. In one example, a system is provided with a combustion chamber formed by a cylinder head coupled to a cylinder block and a pre-chamber in fluidic communication with the combustion chamber. The system is also provided with a purge port coupled to the pre-chamber and structured to flow purge air into the pre-chamber, where the flow of the purge air is driven by operation a purge pump and a piston disposed within the combustion chamber.
1. A method for operation of a pre-chamber ignition system in an engine, comprising:
during a compression stroke, injecting a fuel into a pre-chamber from a pre-chamber fuel injector coupled to the pre-chamber to form an air fuel mixture, igniting the air fuel mixture in the pre-chamber via an ignition device coupled to the pre-chamber; and
during an intake stroke subsequent to the compression stroke, flowing purge air from a positive displacement pump into the pre-chamber through a purge passage traversing the engine;
where the pre-chamber is in fluid communication with a combustion chamber, where the positive displacement pump includes a plunger attached to a valve stem of a valve coupled to the combustion chamber, where the flow of purge air is generated by reciprocal motion of the plunger, and where the valve is an intake valve or an exhaust valve of the combustion chamber.
2. The method of claim 1 , further comprising injecting a fuel from a direct fuel injector into the combustion chamber.
3. The method of claim 1 , further comprising flowing exhaust gas from an exhaust gas recirculation (EGR) conduit to an intake conduit at a location downstream of an inlet of a purge pump inlet passage providing air to the positive displacement pump.
4. The method of claim 1 , where the positive displacement pump includes a valve stem chamber, where the valve stem is an intake valve stem, where the valve stem chamber at least partially circumferentially surrounds the intake valve stem and the plunger is attached to the intake valve stem, and where the purge air flow is generated by the reciprocal motion of the plunger in the valve stem chamber.
5. The method of claim 4 , where the pre-chamber ignition system comprises a plunger valve in the plunger, and where the plunger valve opening and providing fluidic communication between an intake conduit and the valve stem chamber while an intake valve head moves away from an intake valve seat in a cylinder head in an opening direction.
6. The method of claim 1 , where the purge passage is included in the pre-chamber ignition system and is in fluidic communication with a purge port and a valve stem chamber at least partially circumferentially surrounding the valve stem and where the positive displacement pump further includes the valve stem chamber.
7. The method of claim 6 , where the purge passage traverses a section of a cylinder head positioned between an intake valve stem and an exhaust valve stem with regard to a horizontal axis.
8. The method of claim 6 , where when an intake valve head moves toward an intake valve seat in a cylinder head in a closing direction the plunger generates the flow of purge air into the pre-chamber.
9. The method of claim 1 , where a purge port in the pre-chamber ignition system includes a purge valve regulating the flow of the purge air into the pre-chamber and prevents back flow of combustion products into the positive displacement pump and where the purge valve opens when a pressure delta between the pre-chamber and the purge port exceeds a threshold value.
10. The method of claim 1 , where the pre-chamber is positioned vertically above an intake valve head with regard to a central axis of the combustion chamber.
11. The method of claim 1 , where the pre-chamber ignition system comprises the pre-chamber fuel injector and the ignition device.
12. The method of claim 1 , where the pre-chamber ignition system comprises an outlet of an exhaust gas recirculation (EGR) conduit opening into an intake conduit downstream of an inlet of a positive displacement pump passage providing air to the positive displacement pump.
13. The method of claim 1 , further comprising injecting a fuel into the combustion chamber from a port fuel injector.
14. The method of claim 13 , where the fuel is injected into the combustion chamber prior to the injection of the fuel from the pre-chamber fuel injector into the pre-chamber.
15. The method of claim 1 , further comprising jetting gases that are at least partially combusted from the pre-chamber into the combustion chamber.
16. The method of claim 15 , where the gases are jetted through a plurality of orifices in the pre-chamber.
17. The method of claim 15 , where the gases are jetted into the combustion chamber before and/or during a power stroke of a piston in the combustion chamber.
18. The method of claim 15 , where the combustion chamber is formed by a cylinder head coupled to a cylinder block and where the pre-chamber is positioned in the cylinder head.