Pre-chamber for internal combustion engine

1. A combustion pre-chamber apparatus for a main combustion chamber of an internal combustion engine, comprising:

a body defining an internal combustion cavity;

at least one orifice extending through the body, the at least one orifice comprising a first end open to the internal combustion cavity and a second end open to the main combustion chamber, wherein the first end is bigger than the second end;

a sharp edge at the first end of the at least one orifice, the sharp edge structured to decrease a first discharge coefficient of the at least one orifice so as to decrease a mass flow rate of an air-fuel mixture into the internal combustion cavity; and

a fillet at the second end of the at least one orifice, the fillet structured to increase a second discharge coefficient of the at least one orifice so as to increase a mass flow rate of an ignition flame into the main combustion chamber.

2. The combustion pre-chamber apparatus of claim 1 , wherein the orifice has a conical-frustum shape.

3. The combustion pre-chamber apparatus of claim 1 , wherein the orifice converges from the first end to the second end.

4. The combustion pre-chamber apparatus of claim 1 , wherein the at least one orifice has a substantially circular cross-sectional shape.

5. The combustion pre-chamber apparatus of claim 1 , wherein the at least one orifice comprises a plurality of orifices.

6. The combustion pre-chamber apparatus of claim 1 , wherein the fillet has a radius, and wherein a ratio of the radius of the fillet and a diameter of the second end of the at least one orifice is between about 0.01 and about 0.2.

7. The combustion pre-chamber apparatus of claim 1 , wherein a ratio of a cross-sectional area of the second end to a cross-sectional area of the first end is between about 0.5 and about 0.95.

8. The combustion pre-chamber apparatus of claim 1 , wherein first discharge coefficient is different than the second discharge coefficient.

9. The combustion pre-chamber apparatus of claim 8 , wherein the first discharge coefficient is smaller than the second discharge coefficient.

10. The combustion pre-chamber apparatus of claim 1 , wherein a cross-sectional area of the at least one orifice decreases in a direction extending from the first end to the second end.

11. An internal combustion engine, comprising:

a block defining a main combustion cylinder;

a cylinder head coupled to the block above the main combustion cylinder, the cylinder head comprising a combustion pre-chamber, the cylinder head further comprising a plurality of orifices fluidly coupling the main combustion cylinder and the combustion pre-chamber, each of the plurality of orifices converging from a first end open to the combustion pre-chamber to a second end open to the main combustion cylinder;

a sharp edge at the first end of each of the plurality of orifices, the sharp edge structured to decrease a first discharge coefficient of each of the plurality of orifices so as to decrease a mass flow rate of an air-fuel mixture into the combustion pre-chamber;

a fillet at the second end of each of the plurality of orifices, the fillet structured to increase a second discharge coefficient of each of the plurality of orifices so as to increase a mass flow rate of an ignition flame into the main combustion chamber; and

a spark plug at least partially positioned within the combustion pre-chamber.

12. The internal combustion engine of claim 11 , further comprising a fuel and air mixture source in fluid communication with the main combustion cylinder, and a piston movable within the main combustion cylinder, wherein during a compression stroke of the piston a fuel and air mixture within the main combustion cylinder is driven into the combustion pre-chamber via the plurality of orifices.

13. The internal combustion engine of claim 11 , further comprising a fuel injector in fuel injecting communication directly with the combustion pre-chamber.

14. An internal combustion engine, comprising:

a first combustion chamber;

a second combustion chamber;

a plurality of converging orifices, each of the plurality of converging orifices extending from a first end open to the first combustion chamber to a second end open to the second combustion chamber; and

a sharp edge at the first end of each of the plurality of converging orifices, the sharp edge structured to decrease a first discharge coefficient of each of the plurality of converging orifices so as to decrease a mass flow rate of an air-fuel mixture into the first combustion chamber; and

a fillet at the second end of each of the plurality of orifices, the fillet structured to increase a second discharge coefficient of each of the plurality of orifices so as to increase a mass flow rate of an ignition flame into the second combustion chamber.