# US 10,119,493 B2 · Multi-layered piston crown for opposed-piston engines

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- Number: US 10,119,493 B2
- Document ID: US10119493B2
- Status: Granted
- Kind: B2
- Application number: 15/056,909
- Filed: 2016-02-29
- Published: 2017-08-31
- Granted: 2018-11-06
- Earliest claimed: 2016-02-29
- Assignees: Achates Power, Inc.
- Applicants: Achates Power, Inc.
- Inventors: Bryant A. Wagner; Ryan G. Mackenzie
- Web page: https://patentgrep.com/patent/US10119493B2

## CPC

- F02F 3/14: within combustion chambers
- F01B 7/14: acting on different main shafts
- F02B 75/02: Engines characterised by their cycles, e.g. six-stroke
- F02B 75/282: {the pistons having equal strokes}
- F02F 3/285: {the head being provided with an insert located in or on the combustion-gas-swept surface}
- F02B 75/28: Engines with two or more pistons reciprocating within same cylinder or within essentially coaxial cylinders (arranged oppositely relative to main shaft F02B75/24)
- F02B 2075/025: {two}
- F02F 2200/00: Manufacturing
- F02F 2200/06: Casting
- F05C 2251/048: Heat transfer
- F02F: CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F01B: MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES (of rotary-piston or oscillating-piston type F01C; of non-positive-displacement type F01D; internal-combustion engines F02B; combustion-product engine plants F02G; machines or engines, other than of positive-displacement type, for liquids F03B; positive-displacement engines driven by liquids F03C; wind motors F03D; positive-displacement machines for liquids F04B; rotary-piston, or oscillating-piston, positive-displacement machines for liquids F04C)
- F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G)
- F05C: INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES

## 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.

## Claims

### Claim 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 the 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, the barrier layer having a thermal conductivity of 15 W/m·° C. or less and consisting of one of Hastelloy®, Inconel®, Waspaloy®, a René® alloy, a Haynes Alloy, Incoloy®, MP98T, and a CMSX single crystal alloy; an insulating layer having a thermal conductivity of 2 W/m·° C. or less; and a conductive layer located adjacent to the barrier layer, the conductive layer connecting the crown to the rest of piston body and having a thermal conductivity of 25 W/m·° C. or more, 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, the insulating layer does not have a sidewall and has a circumference that fits within the sidewall of the barrier layer, and the crown is attached to the piston body above piston ring grooves by welding.

### Claim 2 (depends on 1)

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.

### Claim 3

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, the barrier layer having a thermal conductivity of 15 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 having a thermal conductivity of 25 W/m·° C. or more; 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 sidewalls, and the crown is attached to the piston body above piston ring grooves by welding.

### Claim 4 (depends on 3)

The piston of claim 3, further comprising: 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 in which the insulating layer does not have a sidewall and has a circumference that fits within the sidewall of the barrier layer.

### Claim 5 (depends on 3)

The piston of claim 3, in which the crown has two or fewer axis of symmetry in plan view.

### Claim 6 (depends on 3)

The piston of claim 3, in which the barrier layer consists of one of Hastelloy®, Inconel®, Waspaloy®, a René® alloy, a Haynes Alloy, Incoloy®, MP98T, and a CMSX single crystal alloy.

### Claim 7

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 having a thermal conductivity of 15 W/m·° C. or less and 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 having a thermal conductivity of 25 W/m·° C. or more and 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 the insulating layer does not have a sidewall and has a circumference that fits within the sidewall of the barrier layer, and joining the barrier layer and the conductive layer comprises joining the barrier and conductive layers along their respective sidewalls.

### Claim 8 (depends on 7)

The method of claim 7, in which the insulating layer comprises a material with a thermal conductivity value of 2 W/m·° C. or less.

### Claim 9 (depends on 7)

The method of claim 7, in which the barrier layer and the conductive layer are manufactured separately and in which joining the barrier and conductive layer comprises welding.

### Claim 10 (depends on 9)

The method of claim 9, in which welding comprises electron beam welding, laser welding, or impulse welding.

### Claim 11 (depends on 7)

The method of claim 7, 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.

### Claim 12 (depends on 7)

The method of claim 7, 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.

### Claim 13 (depends on 12)

The method of claim 12, in which the insulating layer is inserted above the first layer of the crown before casting the second layer of the crown.

### Claim 14 (depends on 7)

The method of claim 7, in which the barrier layer consists of one of Hastelloy®, Inconel®, Waspaloy®, a René® alloy, a Haynes Alloy, Incoloy®, MP98T, and a CMSX single crystal alloy.