Piston for internal combustion engine

Abstract

A piston and an engine are provided that includes various precise configuration parameters, including dimensions, shape and/or relative positioning of combustion chamber features. More particularly, configuration parameters for a piston crown and a piston bowl located within the piston crown are provided. The piston bowl configuration results in a combustion process that yields decreased heat transfer to a cylinder head of the internal combustion engine as well as reduced NOx emissions.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application
α1<60 degrees  (Equation 2)
As previously described, ski jump feature 66 includes radius R4 and outer bowl portion 64 includes radius R5. Radius R4 and radius RS meet the requirements of equation (3).
2.5≤R5/R4≤5.0  (Equation 3)
Spray-targeting feature 80 includes radius R3 with a center of radius that is positioned at depth H3 from valve pocket surface 69. Compound radius 72 includes radius R1 that has a center of radius located radial distance L1 from the axial or longitudinal center of piston 24. Note that radial distance L1 represents the radius of piston bowl 56, making radial distance L1 half the width of piston bowl 56. Depth H3 and radial distance L1 meet the requirements of equation 4.
0.15≤H3/L1≤0.3  (Equation 4)
As will be seen from the description hereinbelow, equations (1), (2) and (4) combine to achieve reduced heat transfer to cylinder head 20 and equations (1), (3) and (4) combine to control smoke, soot or particulate control and fuel consumption or efficiency.

Referring now to FIG. 4, which shows piston 24 moving in a downward or inward stroke toward the engine crankshaft, the benefit of the present disclosure described hereinabove is illustrated. A fuel plume from fuel injectors 42 flows along a path 84 across piston bowl 56 toward spray-targeting feature 80 in piston bowl 56, becoming a diffusion plume as the fuel plume interacts with air from intake valve(s) 28. Radius R3 of spray-targeting feature or lip 80 causes the diffusion plume to bifurcate at spray-targeting lip 80, directing a portion of the diffusion plume along a path 86 into outer bowl portion 64 while the remainder flows along a path 88 toward cylinder head 22. When the diffusion plume reaches compound radius 72, the configuration and dimensions of compound radius 72 cause the diffusion plume to be bifurcated again, guiding a portion of the diffusion plume toward cylinder liner 20 along a path 90, while the remainder of the diffusion plume is directed or recirculated along a path 92 back into piston bowl 56. Outer floor portion 78, which has a length L4 that forms a ratio L4/R3 in the range of 0.2 to 3.0, delays the progression of the diffusion plume toward cylinder head 22, which serves to lower heat transfer to cylinder head 22. The reduced heat transfer occurs because piston 24 is moving in a downward stroke and the gas in cylinder 18 between piston 24 and cylinder head 22 is expanding. Hence, the bifurcation of the diffusion plume near cylinder head 22 has the advantage of preventing excessive heat transfer to cylinder head 22 while using available oxygen within recirculation zones to improve combustion of fuel in the diffusion plume. The rollover radius or feature R1 of compound radius 72 and along edges 82 of valve pocket 69 assists in ensuring a smooth rollover of the diffusion plume onto valve pockets 69 and uppermost surface portion 68. In the absence of rollover feature R1 and rolled edges 82, at least some of the diffusion plume would separate from piston 24 and flow toward cylinder head 22, resulting in higher cylinder head temperatures. In addition to the aforementioned temperature benefits, radius R5 of outer bowl portion 64 and radius R4 of the ski-jump feature or lip 66 promotes an upward turbulence to burn out soot-rich region 94 in combustion chamber 16 by concentrating the highest temperatures combustion chamber 16 along piston bowl 56. Radius R5 and radius R4, which form ratio R5/R4 in the range of 2.5 to 5.0, work with spray-targeting feature 80, defined by radius R3 and axial distance H3, and radius R2 of compound radius 72 to reduce smoke, soot or particulates as well as improving fuel consumption and efficiency. As previously noted, H3 and L1 form the ratio H3/L1 in the range of 0.15 to 0.3.

Testing of the configuration of the present disclosure indicates a temperature reduction in cylinder head 22 in the range of 10 to 15 degrees Fahrenheit as compared to conventional piston designs, depending on engine speed. This configuration also reduces brake specific NOx (BSNOx) by 14% to 17% with an increase in engine out brake specific dry particulate matter (BSDPM) of 11% to 17% and an increase in brake specific fuel consumption of approximately 0.8%. However, the increase in dry particulate matter, or soot, remains within the EPA regulated guidelines and can be controlled further by aftertreatment systems. In addition, the small decrease in fuel consumption may be compensated by increasing the compression ratio of the piston to 18:1, which achieves 1.5% lower fuel consumption than a previous comparable design, thus increasing fuel consumption.

While various embodiments of the disclosure have been shown and described, it is understood that these embodiments are not limited thereto. The embodiments may be changed, modified and further applied by those skilled in the art. Therefore, these embodiments are not limited to the detail shown and described previously, but also include all such changes and modifications.

Claims

1. An internal combustion engine, comprising:

an engine body;

a cylinder head attached to the engine body;

a combustion chamber positioned between the cylinder head and the engine body; and

a piston, including a piston crown that forms a portion of the combustion chamber, located in the engine body, the piston crown including a central axis,

a plurality of valve pockets arranged about the periphery of the piston crown in a plane perpendicular to the central axis,

an uppermost surface portion, and

a piston bowl positioned radially inward from the valve pockets, the piston bowl including:

a compound radius including a radius R1, radius R1 including a center of radius at a radial distance L1 from the central axis, radius R1 connected to and extending inwardly from the valve pockets to form a smooth transition between the valve pockets and the piston bowl;

a frustoconical outer floor portion connected to the compound radius, the frustoconical outer floor portion extending a distance L4 from the compound radius at an angle of to a plane perpendicular to the central axis;

an annular outer bowl portion including a radius R5; and

a spray-targeting feature positioned between the annular outer bowl portion and the frustoconical outer floor portion and including a radius R3 with a center of radius located at an axial distance H3 from the valve pockets,

wherein each of the valve pockets includes a rolled edge extending between the valve pocket and the uppermost surface portion, the rolled edge including a radius to form a smooth transition between the valve pocket and the uppermost surface portion;

wherein a ratio l4/r3 is in the range of 0.2 to 3.0.

2. The internal combustion engine of claim 1, wherein a ratio L4/R3 is in the range of 0.2 to 3.0.

3. The internal combustion engine of claim 2 1, wherein a ratio of H3/L1 is in the range of 0.15 to 0.3.

4. The internal combustion engine of claim 3, wherein α1 is less than 60 degrees.

5. The internal combustion engine of claim 1, wherein a ratio of H3/L1 is in the range of 0.15 to 0.3.

6. The internal combustion engine of claim 5, wherein α1 is less than 60 degrees.

7. The internal combustion engine of claim 1, wherein α1 is less than 60 degrees.

8. The internal combustion engine of claim 1, the piston bowl further including a ski jump feature located radially inward from the annular outer bowl portion, the ski jump feature tangentially connected to the annular outer bowl portion and including a radius R4.

9. The internal combustion engine of claim 8, wherein a ratio R5/R4 is in the range of 2.5 to 5.0.

10. The internal combustion engine of claim 9, wherein a ratio L4/R3 is in the range of 0.2 to 3.0.

11. The internal combustion engine of claim 10, wherein a ratio of H3/L1 is in the range of 0.15 to 0.3.

12. The internal combustion engine of claim 11, wherein α1 is less than 60 degrees.

13. The internal combustion engine of claim 9, wherein a ratio of H3/L1 is in the range of 0.15 to 0.3.

14. The internal combustion engine of claim 13, wherein α1 is less than 60 degrees.

15. The internal combustion engine of claim 9, wherein α1 is less than 60 degrees.

16. An internal combustion engine, comprising:

an engine body;

a cylinder head attached to the engine body;

a combustion chamber positioned between the cylinder head and the engine body; and

a piston, including a piston crown that forms a portion of the combustion chamber, located in the engine body, the piston crown including a central axis, an uppermost surface portion, a plurality of valve pockets arranged about the periphery of the piston crown in a plane perpendicular to the central axis, and a piston bowl positioned radially inward from the valve pockets, the piston bowl including: a compound radius including a radius R1, radius R1 including a center of radius at a radial distance L1 from the central axis, radius R1 connected to and extending inwardly from the valve pockets to form a smooth transition between the valve pockets and the piston bowl; a frustoconical outer floor portion connected to the compound radius, the frustoconical outer floor portion extending a distance L4 from the compound radius at an angle α1 to a plane perpendicular to the central axis; an annular outer bowl portion; and a spray-targeting feature positioned between the annular outer bowl portion and the frustoconical outer floor portion and including a radius R3 with a center of radius located at an axial distance H3 from the end surface, each of the valve pockets including a rolled edge extending between the valve pocket and the uppermost surface portion, the rolled edge including a radius to form a smooth transition between the valve pocket and the uppermost surface portion;

wherein a ratio L4/R3 is in the range of 0.2 to 3.0 and a ratio H3/L1 is in the range of 0.15 to 0.3.

17. The internal combustion engine of claim 16, wherein α1 is less than 60 degrees.

18. An internal combustion engine, comprising:

an engine body;

a cylinder head attached to the engine body;

a combustion chamber positioned between the cylinder head and the engine body; and

a piston, including a piston crown that forms a portion of the combustion chamber, located in the engine body, the piston crown including a central axis, an uppermost surface portion, a plurality of valve pockets arranged about the periphery of the piston crown in a plane perpendicular to the central axis, and a piston bowl positioned radially inward from the valve pockets, the piston bowl including:

a compound radius connected to and extending inwardly from the valve pockets to form a smooth transition between the valve pockets and the piston bowl;

a frustoconical outer floor portion connected to the compound radius, the frustoconical outer floor portion extending from the compound radius at an angle α1 to a plane perpendicular to the central axis;

an annular outer bowl portion including a radius R5;

a spray-targeting feature positioned between the annular outer bowl portion and the frustoconical outer floor portion; and

a ski jump feature positioned between the annular outer bowl portion and the central axis and connected to the angular outer bowl portion, the ski jump feature including a radius R4,

each of the valve pockets including a rolled edge extending between the valve pocket and the uppermost surface portion, the rolled edge including a radius to form a smooth transition between the valve pocket and the uppermost surface portion:

wherein a ratio R5/R4 is in the range of 2.5 to 5.0.

19. The internal combustion engine of claim 18, wherein angle α1 is less than 60 degrees.

20. The internal combustion engine of claim 19, wherein the frustoconical outer floor portion extends radially outward a distance L4 at an angle α1 and the spray-targeting feature has a radius R3 and a ratio L4/R3 is in the range of 0.2 to 3.0.

21. A piston, comprising:

a piston crown including a central axis,

a plurality of valve pockets arranged about the periphery of the piston crown in a plane perpendicular to the central axis,

an uppermost surface portion, and

a piston bowl positioned radially inward from the valve pockets, the piston bowl including:

a compound radius including a radius R1, radius R1 including a center of radius at a radial distance L1 from the central axis, radius R1 connected to and extending inwardly from the valve pockets to form a smooth transition between the valve pockets and the piston bowl;

a frustoconical outer floor portion connected to the compound radius, the frustoconical outer floor portion extending a distance l4 from the compound radius at an angle α1 to a plane perpendicular to the central axis;

an annular outer bowl portion including a radius r5; and a spray-targeting feature positioned between the annular outer bowl portion and the frustoconical outer floor portion and including a radius r3 with a center of radius located at an axial distance h3 from the valve pockets,

wherein each of the valve pockets includes a rolled edge extending between the valve pocket and the uppermost surface portion, the rolled edge including a radius to form a smooth transition between the valve pocket and the uppermost surface portion;

wherein a ratio of h3/L1 is in the range of 0.15 to 0.3.

22. The piston of claim 21, wherein a ratio l4/r3 is in the range of 0.2 to 3.0.

23. The piston of claim 21, wherein α1 is less than 60 degrees.

24. The piston of claim 21, the piston bowl further including a ski jump feature located radially inward from the annular outer bowl portion, the ski jump feature tangentially connected to the annular outer bowl portion and including a radius r4.

25. A piston, comprising:

a piston crown including a central axis, an uppermost surface portion,

a plurality of valve pockets arranged about the periphery of the piston crown in a plane perpendicular to the central axis, and

a piston bowl positioned radially inward from the valve pockets, the piston bowl including:

a compound radius including a radius R1, radius R1 including a center of radius at a radial distance L1 from the central axis, radius R1 connected to and extending inwardly from the valve pockets to form a smooth transition between the valve pockets and the piston bowl;

a frustoconical outer floor portion connected to the compound radius, the frustoconical outer floor portion extending a distance l4 from the compound radius at an angle α1 to a plane perpendicular to the central axis; an annular outer bowl portion; and

a spray-targeting feature positioned between the annular outer bowl portion and the frustoconical outer floor portion and including a radius r3 with a center of radius located at an axial distance h3 from the end surface, each of the valve pockets including a rolled edge extending between the valve pocket and the uppermost surface portion, the rolled edge including a radius to form a smooth transition between the valve pocket and the uppermost surface portion; wherein a ratio l4/r3 is in the range of 0.2 to 3.0 and a ratio h3/L1 is in the range of 0.15 to 0.3.

26. The piston of claim 25, wherein α1 is less than 60 degrees.

27. A piston, comprising:

a piston crown including a central axis, an uppermost surface portion,

a plurality of valve pockets arranged about the periphery of the piston crown in a plane perpendicular to the central axis, and

a piston bowl positioned radially inward from the valve pockets, the piston bowl including:

a compound radius connected to and extending inwardly from the valve pockets to form a smooth transition between the valve pockets and the piston bowl;

a frustoconical outer floor portion connected to the compound radius, the frustoconical outer floor portion extending from the compound radius at an angle α1 to a plane perpendicular to the central axis;

an annular outer bowl portion including a radius r5;

a spray-targeting feature positioned between the annular outer bowl portion and the frustoconical outer floor portion; and

a ski jump feature positioned between the annular outer bowl portion and the central axis and connected to the annular outer bowl portion, the ski jump feature including a radius r4,

each of the valve pockets including a rolled edge extending between the valve pocket and the uppermost surface portion, the rolled edge including a radius to form a smooth transition between the valve pocket and the uppermost surface portion; wherein a ratio r5/r4 is in the range of 2.5 to 5.0.

28. The piston of claim 27, wherein angle α1 is less than 60 degrees.

29. The piston of claim 28, wherein the frustoconical outer floor portion

extends radially outward a distance l4 at an angle α1 and the spray-targeting feature has a radius r3 and a ratio l4/r3 is in the range of 0.2 to 3.0.

30. A piston, comprising:

a piston crown including a central axis,

a plurality of valve pockets arranged about the periphery of the piston crown in a plane perpendicular to the central axis,

an uppermost surface portion, and

a piston bowl positioned radially inward from the valve pockets, the piston bowl including:

a compound radius including a radius R1, radius R1 including a center of radius at a radial distance L1 from the central axis, radius R1 connected to and extending inwardly from the valve pockets to form a smooth transition between the valve pockets and the piston bowl;

a frustoconical outer floor portion connected to the compound radius, the frustoconical outer floor portion extending a distance l4 from the compound radius at an angle α1 to a plane perpendicular to the central axis;

an annular outer bowl portion including a radius r5;

a spray-targeting feature positioned between the annular outer bowl portion and the frustoconical outer floor portion and including a radius r3 with a center of radius located at an axial distance h3 from the valve pockets; and

a frustoconical segment positioned between the spray-targeting feature and the annular outer bowl portion to prevent an undercut in the piston bowl;

wherein each of the valve pockets includes a rolled edge extending between the valve pocket and the uppermost surface portion, the rolled edge including a radius to form a smooth transition between the valve pocket and the uppermost surface portion.