Oil-cooled piston for an internal combustion engine

Patent metadata

Field	Value
Publication number	US-9797337-B2
Application number	US-201514795966-A
Country	US
Kind code	B2
Filing date	Jul 10, 2015
Priority date	Jul 10, 2015
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

A piston for an internal combustion engine. The piston comprises a piston head and an articulated piston skirt. The piston head includes a crown and pin bosses depending from the crown. The piston skirt includes opposed thrust walls, opposed sidewalls, and a transverse bridge extending diametrically across the piston skirt, between the opposed sidewalls. A circumferential cooling gallery is encompassed within an outer circumferential ring belt section of the crown and is in fluid communication with a central cooling passage that extends between the crown and the piston skirt. The central cooling passage extends diametrically across the piston skirt, beneath at least a portion of the ring belt section and beneath at least a portion of an inner combustion bowl section of the crown.

First claim

The invention claimed is:

1. A piston for an internal combustion engine, comprising:
a piston head including a crown and pin bosses depending from said crown, said crown having an outer circumferential ring belt section and an inner combustion bowl section;
an articulated piston skirt including opposed thrust walls, opposed sidewalls, and a transverse bridge extending diametrically across said piston skirt between said opposed sidewalls;
a circumferential cooling gallery encompassed within said ring belt section of said crown; and
a central cooling passage in fluid communication with said circumferential cooling gallery, said cooling passage extending between said crown of said piston head and said piston skirt and extending diametrically across said piston skirt, beneath at least a portion of said ring belt section and beneath at least a portion of said combustion bowl section of said crown,
wherein said transverse bridge has an elevated central region, side regions extending in radially opposite directions from said central region toward said thrust walls, and a drain in said central region through which cooling oil can flow from said central cooling passage into a pin bore gap.

2. The piston set forth in claim 1 wherein said opposed thrust walls are arcuate in shape and said opposed sidewalls are generally planar.

3. The piston set forth in claim 1 wherein said piston head is made of steel and said piston skirt is made of aluminum or an aluminum alloy.

4. The piston set forth in claim 1 wherein said opposed sidewalls of said skirt are located radially inward of said pin bosses of said piston head.

5. The piston set forth in claim 1 wherein said central cooling passage is at least partially defined by a lower surface of said ring belt section of said crown, a lower surface of said combustion bowl section of said crown, and a transverse flow surface of said transverse bridge of said piston skirt.

6. The piston set forth in claim 1 wherein said transverse bridge includes lateral fins that extend in a generally lateral direction along said opposed sidewalls of said piston skirt.

7. The piston set forth in claim 6 wherein said lateral fins extend in a generally upward direction from said bridge, toward said crown, to free ends.

8. The piston set forth in claim 7 wherein said free ends of said lateral fins are spaced from a lower surface of said combustion bowl section of said crown by a gap in the range of 2 mm to 4 mm.

9. The piston set forth in claim 1 wherein one of said side regions of said bridge includes an inlet opening through which cooling oil can be introduced into said central cooling passage.

10. The piston set forth in claim 9 wherein said ring belt section of said crown includes an inlet port through which cooling oil can be introduced into said circumferential cooling gallery and an outlet port through which cooling oil can be discharged from said circumferential cooling gallery.

11. The piston set forth in claim 10 wherein said inlet opening in said side region of said bridge is located beneath said inlet port in said ring belt section of said crown and at least partially overlaps with said inlet port.

12. An articulated piston skirt, comprising:
diametrically opposed arcuate thrust walls extending in a generally longitudinal direction from an upper end to a lower end of said piston skirt;
opposed generally planar sidewalls extending across said piston skirt, from one arcuate thrust wall to another and from said upper end to said lower end of said piston skirt;
a transverse bridge extending diametrically across said piston skirt, from one of said arcuate thrust walls to another, between said generally planar sidewalls, said transverse bridge including a transverse flow surface over which cooling oil can flow from one of said arcuate thrust walls to another;
lateral fins extending in a generally upward direction from said bridge and in a generally lateral direction along said generally planar sidewalls; and
a central channel defined above said transverse flow surface of said transverse bridge and bounded on opposite sides by said lateral fins,
wherein said transverse bridge is configured to at least partially define a central cooling passage that extends diametrically across said piston skirt, from one of said arcuate thrust walls to another.

13. The piston skirt set forth in claim 12 wherein said arcuate thrust walls and said generally planar sidewalls define a radially outer periphery of said skirt.

14. The piston skirt set forth in claim 12 wherein said transverse bridge has an elevated central region, side regions that extend in radially opposite directions away from said central region to said arcuate thrust walls, and a drain in said central region through which cooling oil can flow.

15. The piston skirt set forth in claim 12 comprising axially aligned pin bores defined in said generally planar sidewalls.

16. A piston for an internal combustion engine, comprising:
the piston skirt of claim 12 ;
a piston head including a crown and pin bosses, said crown of said piston head comprising an outer circumferential ring belt section and an inner combustion bowl section, and each of said pin bosses depending from said crown and defining a pin bore; and
a circumferential cooling gallery encompassed within said ring belt section of said crown,
wherein said articulated piston skirt is positioned beneath said crown of said piston head, and said generally planar sidewalls of said piston skirt are located radially inward of said pin bosses of said piston head,
wherein said lateral fins extend in a generally upward direction from said bridge, toward said crown, to free ends, and
wherein said free ends of said lateral fins are spaced apart from a lower surface of said inner combustion bowl section of said crown.

17. The piston set forth in claim 16 comprising a central cooling passage, said cooling passage being at least partially defined by a lower surface of said ring belt section of said crown, said lower surface of said combustion bowl section of said crown, and said transverse flow surface of said transverse bridge of said piston skirt.

18. The piston set forth in claim 17 wherein said arcuate thrust walls of said piston skirt have upper ends located below and spaced apart from said lower surface of said ring belt section of said crown, and wherein said central channel extends between said upper ends of said thrust walls and is configured to collect cooling oil above said transverse flow surface of said transverse bridge within said central cooling passage.

19. A piston assembly for an internal combustion engine, comprising:
the piston of claim 16 , wherein axially aligned pin bores are defined in said generally planar sidewalls of said piston skirt;
a connecting rod having a small end that defines a pin bore, said small end of said connecting rod being positioned between said arcuate thrust walls and between said generally planar sidewalls of said piston skirt; and
a piston pin extending through said pin bores of said piston head, said pin bores of said piston skirt, and said pin bore of said connecting rod.

20. A piston assembly for an internal combustion engine, comprising:
a piston head including a crown and pin bosses depending from said crown, said pin bosses having axially aligned pin bores, and said crown comprising a circumferential upper wall, a circumferential lower wall, a combustion wall, an outer ring belt wall, and an annular inner wall, wherein said outer ring bel

Assignees

• Mahle Int Gmbh

Inventors

• Nguyen Giang The

Classifications

• F02F3/22

  the fluid being liquid · CPC title

• F02F3/0069 Primary

  the crown and skirt being interconnected by the gudgeon pin · CPC title

• F01P3/10

  Cooling by flow of coolant through pistons · CPC title

• F16J1/09

  with means for guiding fluids (F16J1/08 takes precedence) · CPC title