Piston bowl for improved combustion stability

Patent metadata

Field	Value
Publication number	US-10400663-B2
Application number	US-201715844876-A
Country	US
Kind code	B2
Filing date	Dec 18, 2017
Priority date	Dec 18, 2017
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

A piston comprises a crown portion with a contoured bowl having a reentrant surface extending from the top squish surface that connects to a lower sidewall surface that connects to a swirl pocket surface disposed adjacent the bottom bowl surface.

First claim

What is claimed is:

1. A piston configured to reciprocate in the bore of an engine, the piston comprising:
a body that includes a connecting rod attachment portion and a crown portion;
the crown portion includes a generally cylindrical shape defining a cylindrical axis, circumferential direction and a radial direction, the crown portion further including a circular annular top squish surface with an outer circumference, a wall portion extending axially away from the squish surface proximate the outer circumference of the squish surface defining a bottom wall surface, the crown portion further defining a contoured bowl extending axially from the top squish surface toward the interior of the body, terminating at a bottom bowl surface and the wall portion further defining a cooling gallery extending axially from the bottom wall surface toward the top squish surface;
wherein the contoured bowl includes a symmetrical annular shape about the cylindrical axis and further includes a reentrant surface extending from the top squish surface that connects to a lower sidewall surface that connects to a swirl pocket surface disposed adjacent the bottom bowl surface;
the swirl pocket surface includes an arcuate portion and a bottom angled surface that connects the arcuate portion of the swirl pocket surface to the bottom bowl surface and the bottom bowl surface is flat and is perpendicular to the cylindrical axis; and
the reentrant surface is a conical reentrant surface that forms an included reentrant angle with the top squish surface ranging from 45 to 80 degrees and the conical reentrant surface and lower sidewall surface form a sidewall and a sidewall angle between the conical reentrant surface and the lower sidewall surface ranging from 110 to 140 degrees.

2. The piston of claim 1 , wherein the lower sidewall surface is a lower conical surface and the contoured bowl further includes a top blend transitioning from the conical reentrant surface to the lower conical surface.

3. The piston of claim 2 , wherein the contoured bowl further includes a bottom blend transitioning from the bottom angled surface to the bottom bowl surface.

4. The piston of claim 3 , wherein the bottom bowl surface has a circular shape defining a bottom bowl surface diameter and the conical reentrant surface forms a circular intersection with the top squish surface, the circular intersection defining a circular intersection diameter and a ratio of the circular intersection diameter to the bottom bowl surface diameter ranges from 1.75 to 3.50.

5. The piston of claim 1 , wherein the bottom bowl surface is flat and perpendicular to the cylindrical axis and the swirl pocket surface includes an arcuate portion that defines a lower axial extremity that is disposed axially below relative to the bottom bowl surface.

6. The piston of claim 5 , wherein the body defines a first axial distance from the top squish surface to the lower axial extremity, the connecting rod attachment portion defines a cylindrical aperture defining a connecting rod pivot axis that is perpendicular to the cylindrical axis of the crown portion, the body further defines a second axial distance from the lower axial extremity of the arcuate portion to the pivot axis, and a ratio of the second axial distance to the first axial distance ranges from 1.25 to 2.5.

7. The piston of claim 1 , wherein the body includes a cooling gallery sidewall surface, partially defining the cooling gallery, disposed adjacent the lower sidewall surface that is parallel with the lower sidewall surface.

8. The piston of claim 1 , wherein the contoured bowl includes a swirl pocket surface disposed adjacent the bottom bowl surface that connects the lower sidewall surface to the bottom bowl surface.

9. The piston of claim 8 , wherein the bottom bowl surface is flat and has a circular configuration.

10. The piston of claim 9 , wherein swirl pocket surface includes a concave arcuate portion defining a lower axial extremity disposed axially below relative to the bottom bowl surface, and the body defines a first axial distance from the top squish surface to the lower axial extremity, the connecting rod attachment portion defines a cylindrical aperture defining a connecting rod pivot axis that is perpendicular to the cylindrical axis of the crown portion, the body further defines a second axial distance from the lower extremity of the concave arcuate portion to the pivot axis, and a ratio of the second axial distance to the first axial distance ranges from 1.25 to 2.5.

11. The piston of claim 10 , wherein the body defines a third axial distance from the top squish surface to the bottom bowl surface and a ratio of the first axial distance to the third axial distance ranges from 1.0 to 1.4.

12. The piston of claim 11 , wherein the body further includes a blend surface joining the reentrant conical surface to the lower sidewall surface, defines a maximum diameter of the bowl at the blend surface, and the ratio of the maximum diameter to the first axial distance ranges from 2.75 to 5.0.

13. The piston of claim 12 , wherein the crown portion defines a crown diameter and a ratio of the crown diameter to the maximum diameter of the bowl ranges from 1.3 to 1.8.

14. A piston configured to reciprocate in the bore of an engine, the piston comprising:
a body that includes a connecting rod attachment portion and a crown portion;
the crown portion includes a generally cylindrical shape defining a cylindrical axis, circumferential direction and a radial direction, the crown portion further including a circular annular top squish surface with an outer circumference, a wall portion extending axially away from the squish surface proximate the outer circumference of the squish surface, defining a bottom wall surface, the crown portion further defining a contoured bowl extending axially from the top squish surface toward the interior of the body, terminating at a bottom bowl surface and the wall portion further defining a cooling gallery extending axially from the bottom wall surface toward the top squish surface; and
wherein the contoured bowl includes a symmetrical annular shape about the cylindrical axis and further includes a lower sidewall surface and the cooling gallery includes a cooling gallery sidewall surface disposed proximate the lower sidewall surface being parallel with the lower sidewall surface and the contoured bowl includes a conical reentrant surface extending from the top squish surface forming an angle with the lower sidewall surface ranging from 110 degrees to 140 degrees.

15. The piston of claim 14 , wherein the lower sidewall surface forms an acute angle with the cylindrical axis ranging from zero to 30 degrees.

16. The piston of claim 14 , wherein the cooling gallery defines a cooling gallery height along a direction parallel with the cylindrical axis, the cooling gallery sidewall surface defines a cooling gallery sidewall surface curvilinear length measured in a plane containing the radial direction and the cylindrical axis along the cooling gallery sidewall surface, and a ratio of the height of the cooling gallery to the cooling gallery sidewall surface curvilinear length ranges from 1.0 to 1.9.

Assignees

• Caterpillar Inc

Inventors

• Ness Aaron
• Howard Jeff
• Uddanda Sri Harsha
• BURGER Lucas Allen

Classifications

• F02B43/00

  Engines characterised by operating on gaseous fuels; Plants including such engines (engines characterised by the gas-air charge being ignited by compression ignition of an additional fuel F02B7/06; engines convertible from gas to other fuel consumption F02B69/04) · CPC title

• F02B23/08

  with positive ignition · CPC title

• F02B23/0672

  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 title

• F02F3/28

  Other pistons with specially-shaped head · CPC title

• F02B23/0621 Primary

  Squish flow · CPC title