Multi-layered piston crown for opposed-piston engines

Patent metadata

Field	Value
Publication number	US-10634091-B2
Application number	US-201816178966-A
Country	US
Kind code	B2
Filing date	Nov 2, 2018
Priority date	Feb 29, 2016
Publication date	Apr 28, 2020
Grant date	Apr 28, 2020

Abstract

A piston crown for a piston of a pair of pistons in a two-stroke, opposed-piston, compression ignition combustion engine has a barrier layer and a conductive layer. The barrier layer at least partially surrounds a combustion chamber formed by the piston crown and an end surface of an opposing piston. The conductive layer connects the crown to the rest of the piston body. The barrier layer and the conductive layer are joined either through welding or through the fabrication process. Optionally, the piston crown includes an insulating layer between the barrier and conductive layers.

First claim

The invention claimed is:

1. An internal combustion engine including at least one cylinder with longitudinally-separated exhaust and intake ports and a pair of pistons disposed in opposition to one another in a bore of the cylinder, each piston including:
a piston body with a crown at one end; and
an end surface on the crown, in which an end surface of a first piston has a bowl that cooperates with the end surface of an opposing piston to define a combustion chamber,
the crown comprising:
a barrier layer located in the end surface such that the combustion chamber is enclosed at least in part by the barrier layer;
an insulating layer; and
a conductive layer located adjacent to the barrier layer, the conductive layer connecting the crown to the piston body by welding above piston ring grooves,

in which:
the insulating layer is between the barrier layer and the conductive layer,
the barrier layer and the conductive layer each have a bowl, a pair of notches, and a sidewall portion, and
the insulating layer does not have a sidewall portion and has a circumference that fits within the sidewall portion of the barrier layer.

2. The internal combustion engine of claim 1 , further comprising, in each piston at least one void between the barrier layer and the conductive layer of the crown.

3. The internal combustion engine of either claim 1 or 2 , wherein the insulating layer has a thermal conductivity of 2 W/m·° C. or less.

4. The internal combustion engine of claim 1 , in which:
the barrier layer has a thermal conductivity of 15 W/m·° C. or less; and
the conductive layer has a thermal conductivity of 25 W/m·° C. or more.

5. A piston for a two-stroke, opposed-piston, internal combustion engine, comprising: a piston body with a crown at one end, the crown including; an end surface formed on the crown, the end surface including an elongated bowl that cooperates with an opposing piston end surface to define a combustion chamber, a barrier layer located in the end surface such that the combustion chamber is enclosed at least in part by the barrier layer; an insulating layer between the barrier layer and the conductive layer, the insulating layer having a thermal conductivity of 2 W/m-C or less; a conductive layer located adjacent to the barrier layer, the conductive layer connecting the crown to the rest of piston body; and at least one void formed from a discontinuity between the barrier layer and the conductive layer, in which: the barrier layer and the conductive layer each have a bowl, a pair of notches, and a sidewall portion, the barrier layer and the conductive layer are joined along their respective sidewall portions, and the crown is attached to the piston body above piston ring grooves by welding.

6. The piston of claim 5 , in which:
the barrier layer has a thermal conductivity of 15 W/m·° C. or less; and
the conductive layer has a thermal conductivity of 25 W/m·° C. or more.

7. The piston of claim 5 , in which the crown has two or fewer axes of symmetry in plan view.

8. A method of making a piston crown for a piston for a two-stroke, opposed-piston, internal combustion engine, the method comprising:
forming a barrier layer configured to at least partially enclose a combustion chamber formed by the piston crown and an end surface of an opposing piston;
forming a conductive layer configured to connect the piston crown to other components of the piston;
forming an insulating layer configured for insertion between the barrier layer and the conductive layer; and
joining the barrier layer and the conductive layer,

in which:
the barrier layer and the conductive layer each have a bowl, a pair of notches, and a sidewall portion; and
the insulating layer does not have a sidewall portion and has a circumference that fits within the sidewall portion of the barrier layer.

9. The method of claim 8 , in which joining the barrier layer and the conductive layer comprises joining the barrier and conductive layers along their respective sidewalls.

10. The method of claim 8 , in which, the barrier layer comprises a material with a thermal conductivity value of 15 M/w·° C. or less and the conductive layer comprises a material with a thermal conductivity value of 25 W/m·° C. or more.

11. The method of claim 8 , in which the insulating layer comprises a material with a thermal conductivity value of 2 W/m·° C. or less.

12. The method of claim 8 , in which the barrier layer and the conductive layer are manufactured separately and in which joining the barrier and conductive layer comprises welding.

13. The method of claim 12 , in which welding comprises electron beam welding, laser welding, or impulse welding.

14. The method of claim 8 , in which:
the barrier layer and the conductive layer are manufactured separately;
the insulating layer comprises ceramic particles that are formed into the insulating layer by 3D printing, casting, or molding; and
in which joining the barrier and conductive layer comprises welding.

15. The method of claim 8 , in which:
the barrier layer is cast as a first layer of the crown and the conductive layer is cast as a second layer of the crown above the first layer; or
the conductive layer is cast as a first layer of the crown and the barrier layer is cast as a second layer of the crown above the first layer.

16. The method of claim 15 , in which:
the barrier layer is cast as a first layer of the crown, the conductive layer is cast as a second layer of the crown above the first layer, and the insulating layer is inserted above the first layer of the crown before casting the second layer of the crown; or
the conductive layer is cast as a first layer of the crown, the barrier layer is cast as a second layer of the crown above the first layer, and the insulating layer is inserted above the first layer of the crown before casting the second layer of the crown.

17. An internal combustion engine including at least one cylinder with longitudinally-separated exhaust and intake ports and a pair of pistons disposed in opposition to one another in a bore of the cylinder, at least one piston of the pair of pistons comprising the piston of claim 5 .

18. The internal combustion engine of claim 17 , in which
the barrier layer of the at least one piston has a thermal conductivity of 15 W/m·° C. or less; and
the conductive layer of the at least one piston has a thermal conductivity of 25 W/m·° C. or more.

19. The internal combustion engine of claim 17 , in which the crown of the at least one piston has two or fewer axes of symmetry in plan view.

Assignees

• Achates Power Inc

Inventors

• Wagner Bryant A
• Mackenzie Ryan G

Classifications

• F05C2251/048

  Heat transfer · CPC title

• F02B75/282

  the pistons having equal strokes · CPC title

• F02F2200/00

  Manufacturing · CPC title

• F02B75/02

  Engines characterised by their cycles, e.g. six-stroke · CPC title

• F01B7/14

  acting on different main shafts · CPC title