Diesel combustion chamber

• US 6,997,158 B1
• Filed: 10/07/2004
• Issued: 02/14/2006
• Est. Priority Date: 10/07/2004
• Status: Active Grant

• Current Assignee: International Engine Intellectual Property Company, LLC (Volkswagen AG)
• Original Assignee: International Engine Intellectual Property Company, LLC (Volkswagen AG)
• Inventors: Liu, Zhengbai
• Primary Examiner(s): HUYNH, HAI H
• Application Number:
  US10/960,662
• Time in Patent Office: 495 Days
• Field of Search: 123/269, 123/279, 123/285, 123/307, 123/193.6, 123/281, 123/282
• US Class Current: 123/279
• CPC Class Codes: F02B 23/0672 Omega-piston bowl, i.e. the combustion space having a central projection pointing towards the cylinder head and the surrounding wall being inclined towards the cylinder center axis the surrounding wall being exactly vertical F02B23/0696
• CPC Class Codes: F02B 3/06 with compression ignition compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A combustion chamber assembly for use in a diesel engine includes a combustion chamber being defined intersecting a crown of a piston, the combustion chamber being defined by a first curved surface having a reentrancy formed proximate a first curved surface first end and having a post formed proximate a first curved surface second end, a corner being formed at a juncture of the first curved surface second end and the post, adjacent surfaces being direct smooth junctures. A piston and a method of forming a combustion chamber are further included.

Claims

1. A combustion chamber assembly for use in a diesel engine, comprising:

a combustion chamber being formed free of flat surfaces and being defined intersecting a crown of a piston, the combustion chamber being defined by a first curved surface having a reentrancy formed proximate a first curved surface first end and having a post formed proximate a first curved surface second end, a corner being formed at a juncture of the first curved surface second end and the post, adjacent surfaces having smooth junctures therebetween.

2. The combustion chamber assembly of claim 1, a combustion chamber center portion being defined at least in part by the post, a post surface being a convex spherical surface, the spherical surface having a radius and an origin, the spherical surface radius being substantially greater than a radius of the first curved surface;

and

the combustion chamber first curved surface being a concave annular surface and having an origin of the radius, the first curved surface providing a minor part of the combustion chamber reentrancy.

3. The combustion chamber assembly of claim 2, wherein the reentrancy is formed by four sequentially joined annular surfaces in cooperation with the first curved surface.

4. The combustion chamber assembly of claim 3, the four sequentially joined annular surfaces and the first curved surface comprising three concave annular surfaces and two convex annular surfaces.

5. The combustion chamber assembly of claim 2, wherein the origin of the post spherical surface is disposed on the center axis of the combustion chamber, the center axis of the combustion chamber being coaxial with a center axis of the piston.

6. The combustion chamber assembly of claim 2, wherein the ratio of a radius of a center portion convex spherical surface, RS1, of the combustion chamber to a maximum bowl diameter, D2, is greater than 0.15 and less than 0.65.

7. The combustion chamber assembly of claim 6, wherein the ratio of the radius of the center portion convex spherical surface, RS1, of the combustion chamber to the maximum bowl diameter, D2, is substantially 0.497.

8. The combustion chamber assembly of claim 2, wherein the ratio of a combustion chamber bowl diameter D2 to a piston diameter D1 is greater than 0.45 and less than 0.85.

9. The combustion chamber assembly of claim 8, wherein the ratio of the combustion chamber bowl diameter D2 to the piston diameter D1 is preferably substantially 0.587.

10. The combustion chamber assembly of claim 2, wherein the ratio of a diameter of the bowl lip D3 to a maximum bowl diameter D2 is greater than 0.45 and less than 0.995.

11. The combustion chamber assembly of claim 10, wherein the ratio of the diameter of the bowl lip D3 to the piston diameter D2 is substantially 0.94.

12. The combustion chamber assembly of claim 2, wherein the ratio of a concave annular surface R2 to a maximum diameter of the bowl D2 is between 0.05 and 0.35.

13. The combustion chamber assembly of claim 12, wherein the ratio of the annular surface R2 to the maximum diameter of the bowl D2 is substantially 0.129.

14. The combustion chamber assembly of claim 2 wherein the ratio of a convex annular surface R3 to a maximum diameter of the bowl D2 is between 0.15 and 0.45.

15. The combustion chamber assembly of claim 14, wherein the ratio of the annular surface R3 to the maximum diameter of the bowl D2 is substantially 0.292.

16. The combustion chamber assembly of claim 2, wherein the ratio of a maximum bowl depth H1 to a maximum bowl diameter D2 is between 0.15 and 0.55.

17. The combustion chamber assembly of claim 16, wherein the ratio of the maximum bowl depth H1 to the maximum bowl diameter D2 is preferably substantially 0.292.

18. The combustion chamber assembly of claim 2, wherein a ratio of a height of the bowl post H2 to a maximum bowl diameter D2 is between 0.05 and 0.35.

19. The combustion chamber assembly of claim 18, wherein the ratio of the bowl post height H2 to the maximum bowl diameter D2 is preferably substantially 0.181.

20. The combustion chamber assembly of claim 2, wherein a ratio of a distance between the bowl reentrancy center and the piston top surface H3 to a maximum bowl diameter D2 is between 0.05 and 0.25.

21. The combustion chamber assembly of claim 20, wherein a ratio of a distance between the bowl reentrancy center and the piston top surface H3 to a maximum bowl diameter D2 is preferably 0.056.

22. The combustion chamber assembly of claim 2, wherein the ratio of the radius of the curved surface R4 to the maximum bowl diameter D2 is between 0.015 and 0.15.

23. The combustion chamber assembly of claim 22, wherein the ratio of the radius of the curved surface R4 to the maximum bowl diameter D2 is preferably substantially 0.028.

24. The combustion chamber assembly of claim 2, wherein the ratio of the radius of the curved surface R5 to the maximum bowl diameter D2 is between 0.05 and 0.25.

25. The combustion chamber assembly of claim 24, wherein the ratio of the radius of the curved surface R5 to the maximum bowl diameter D2 is preferably substantially 0.073.

26. The combustion chamber assembly of claim 1, wherein the juncture between the first curved surface and the post spherical surface is effected by an interposed small annular surface.

27. The combustion chamber assembly of claim 1, wherein the combustion chamber is symmetrical about a combustion chamber center axis.

28. The combustion chamber assembly of claim 1, the combustion chamber having a central axis, the combustion chamber central axis being coincident with a piston central axis.

29. A piston of a diesel engine having a combustion chamber assembly defined therein, comprising:

a combustion chamber being formed free of flat surfaces and being defined intersecting a crown of the piston, the combustion chamber being defined by a first curved surface having a reentrancy formed proximate a first curved surface first end and having a post formed proximate a first curved surface second end, a corner being formed at a juncture of the first curved surface second end and the post, adjacent surfaces having smooth junctures therebetween.

30. The piston of claim 29, a combustion chamber center portion being defined at least in part by the post, a post surface being a convex spherical surface, the spherical surface having a radius and an origin, the spherical surface radius being substantially greater than a radius of the first curved surface;

and

the combustion chamber first curved surface being a concave annular surface and having an origin of the radius, the first curved surface providing a minor part of the combustion chamber reentrancy.

31. The piston of claim 30, wherein the reentrancy is formed by four sequentially joined annular surfaces in cooperation with the first curved surface.

32. The piston of claim 31, the four sequentially joined annular surfaces and the first curved surface comprising three concave annular surfaces and two convex annular surfaces.

33. The piston of claim 30, wherein the origin of the post spherical surface is disposed on the center axis of the combustion chamber, the center axis of the combustion chamber being coaxial with a center axis of the piston.

34. The piston of claim 29, wherein the juncture between the first curved surface and the post spherical surface is effected by an interposed small annular surface.

35. The piston of claim 29, wherein the combustion chamber is symmetrical about a combustion chamber center axis.

36. The piston of claim 29, the combustion chamber having a central axis, the combustion chamber central axis being coincident with a piston central axis.

37. A method of forming a combustion chamber for use in a diesel engine, comprising:

forming a combustion chamber intersecting a crown of a piston free of flat surfaces, defining the combustion chamber by a first curved surface having a reentrancy formed proximate a first curved surface first end and having a post formed proximate a first curved surface second end, forming a corner at a juncture of the first curved surface second end and the post and forming adjacent surfaces with smooth junctures therebetween.

38. The method of claim 37, including defining a combustion chamber center portion at least in part by the post, forming a post surface as a convex spherical surface, the spherical surface having a radius and an origin, and forming the spherical surface radius substantially greater than a radius of the first curved surface;

and

forming the combustion chamber first curved surface as a concave annular surface and having an origin and a radius, the first curved surface providing a minor part of the combustion chamber reentrancy.

39. The method of claim 38, including forming the reentrancy by four sequentially joined annular surfaces in cooperation with the first curved surface.

40. The method of claim 39, including comprising the four sequentially joined annular surfaces and the first curved surface of three concave annular surfaces and two convex annular surfaces.

41. The method of claim 39, including disposing the origin of the post on the center axis of the combustion chamber and disposing the center axis of the combustion chamber coaxially with a center axis of the piston.

42. The method of claim 37, including effecting the juncture between the first curved surface and the post by an interposed small annular surface.

43. The method of claim 37, including forming the combustion chamber symmetrically about a combustion chamber center axis.