Piston with thermally insulated crown

Patent metadata

Field	Value
Publication number	US-9687942-B2
Application number	US-201414474906-A
Country	US
Kind code	B2
Filing date	Sep 2, 2014
Priority date	Sep 2, 2014
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

Exemplary pistons and methods are disclosed. A piston may include a piston body defining a piston axis, the body including radially inner and outer body mating surfaces, and an annular ring cooperating with the piston body to form a continuous upper combustion bowl surface having a radially inner portion defined by the piston body and a radially outer portion defined by the annular ring. The annular ring includes a radially inner ring mating surface and a radially outer ring mating surface, wherein at least one of the annular ring mating surfaces is joined with the corresponding piston body mating surface. The annular ring and piston body cooperate to define an annular gap therebetween configured to thermally insulate the piston body from the annular ring.

First claim

What is claimed is:

1. A method, comprising:
providing a piston having a piston body defining a piston axis, the piston body including radially inner and outer body mating surfaces;
assembling an annular ring with the piston body such that the piston body and the annular ring cooperate to form a continuous upper combustion bowl surface having a radially inner portion defined by the piston body and a radially outer portion defined by the annular ring, the annular ring including a radially inner ring mating surface and a radially outer ring mating surface;
joining the body to the annular ring along at least one of the radially inner and outer mating surfaces of the body and the annular ring;
wherein the annular ring and piston body cooperate to define an annular gap therebetween that is left empty or includes air therein during an operation of the piston, forming a thermal break between the combustion bowl and the piston body, the annular gap positioned to thermally insulate the piston body from the annular ring during the operation of the piston; and
wherein the annular gap has a thickness of approximately 1 mm.

2. The method of claim 1 , further comprising establishing the joining of the body to the annular ring along the at least one of the radially inner and outer mating surfaces of the body and the annular ring as including laser welding.

3. The method of claim 1 , wherein the piston body includes a skirt configured to interface with an engine bore surface.

4. The method of claim 1 , further comprising forming a weld spatter on a surface, the surface at least partially defining the annular gap.

5. The method of claim 1 , further comprising fully penetrating a weld joint including an entire length of the at least one of the radially inner and outer mating surfaces of the body and the annular ring.

6. The method of claim 1 , further comprising establishing a primary path of heat transfer across the annular gap during operation of an engine into which the piston is installed as convection.

7. The method of claim 1 , further comprising establishing the ring as being formed from a first material and the body being formed from a second material; wherein the first material has a higher oxidation resistance than the second material.

8. The method of claim 1 , wherein the piston body includes an annular gap vent that allows for communication of an interior of the annular gap with an external atmosphere during the operation of the piston.

9. A method, comprising:
providing a piston having a piston body that defines a piston axis, the piston body including radially inner and outer body mating surfaces;
assembling an annular ring with the piston body such that the piston body and the annular ring cooperate to form a continuous upper combustion bowl surface having a radially inner portion defined by the piston body and a radially outer portion defined by the annular ring, the annular ring including a radially inner ring mating surface and a radially outer ring mating surface;
joining the body to the annular ring along at least one of the radially inner and outer mating surfaces of the body and the annular ring;
wherein the annular ring and piston body enclose an annular gap, the annular gap having air therein during an engine operation, the annular gap positioned to thermally insulate the piston body from the annular ring during the operation of the engine into which the piston is installed; and
wherein the annular gap has a thickness of approximately 1 mm, and the piston body includes an annular gap vent that allows for communication of an interior of the annular gap with an external atmosphere during the operation of the engine.

10. The method of claim 9 , further comprising operating an engine with the piston.

11. The method of claim 9 , further comprising establishing the joining of the body to the annular ring along the at least one of the radially inner and outer mating surfaces of the body and the annular ring as including laser welding.

12. The method of claim 9 , further comprising forming a weld spatter on a surface, the surface at least partially defining the annular gap.

13. The method of claim 9 , further comprising fully penetrating a weld joint including an entire length of the at least one of the radially inner and outer mating surfaces of the body and the annular ring.

14. The method of claim 9 , further comprising establishing the ring as being formed from a first material and the body being formed from a second material; wherein the first material has a higher oxidation resistance than the second material.

15. A piston, comprising:
a piston body defining a piston axis, the body including radially inner and outer body mating surfaces;
an annular ring cooperating with the piston body to form a continuous upper combustion bowl surface having a radially inner portion defined by the piston body and a radially outer portion defined by the annular ring, the annular ring including a radially inner ring mating surface and a radially outer ring mating surface, wherein the annular ring mating surfaces are joined with corresponding piston body mating surfaces; and
wherein the annular ring and piston body define an annular gap therebetween that is left empty or includes air therein during an operation of the piston in an engine, the annular gap configured to thermally insulate the piston body from the annular ring; and
wherein the annular gap has a thickness of approximately 1 mm.

16. The piston of claim 15 , wherein the piston body includes a skirt configured to interface with an engine bore surface.

17. The piston of claim 15 , wherein the piston body includes an annular gap vent that allows for communication of an interior of the annular gap with an external atmosphere during the operation of the piston in the engine.

Assignees

• Mahle Int Gmbh

Inventors

• Flowers William

Classifications

• F16J1/006

  of different materials · CPC title

• F02F3/02

  having means for accommodating or controlling heat expansion · CPC title

• B23P15/10 Primary

  pistons · CPC title

• F02F3/003

  the parts being connected by casting, brazing, welding or clamping · CPC title