# US 10,871,099 B2 · Piston cooling for opposed-piston engine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,871,099 B2 - Document ID: US10871099B2 - Status: Granted - Kind: B2 - Application number: 15/687,368 - Filed: 2017-08-25 - Published: 2017-12-28 - Granted: 2020-12-22 - Earliest claimed: 2015-01-14 - Assignees: Achates Power, Inc. - Applicants: Achates Power, Inc. - Inventors: Ryan G. Mackenzie - Web page: https://patentgrep.com/patent/US10871099B2 ## CPC - F01P 3/10: Cooling by flow of coolant through pistons - F01B 7/02: with oppositely reciprocating pistons - F02B 23/06: the combustion space being arranged in working piston (F02B23/04 takes precedence) - 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) - F02F 3/22: the fluid being liquid - F01P 3/08: Cooling of piston exterior only, e.g. by jets - F01P 11/02: Liquid-coolant {filling}, overflow, venting, or draining devices (automatic draining during freezing conditions F01P11/20) - Y02T 10/12: Improving ICE efficiencies - F01P: COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES (arrangements in connection with cooling of propulsion units in vehicles B60K11/00; heat-transfer, heat-exchange or heat-storage materials C09K5/00; {cooling of gas-turbine engines F02C7/12}; heat exchange in general, radiators F28) - 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) - F02F: CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract Pistons for opposed-piston engines include an interior annular cooling gallery. The gallery is provided with inlet and drain passageways constructed to shield a jet of liquid coolant entering the gallery, thereby reducing interference between the incoming jet and liquid coolant circulating in the gallery. ## Claims ### Claim 1 A piston for an opposed-piston engine, comprising: a crown with an end surface shaped to define a combustion chamber with an end surface of an opposing piston in an opposed-piston engine; a separate skirt part joined to the crown and including a piston sidewall extending from the crown to an open end of the skirt part; an annular cooling gallery defined between the crown and the skirt part; a first set of ring grooves formed in an outer peripheral surface of the crown; a second set of ring grooves formed in a portion of the sidewall near the open end of the skirt; the sidewall comprising two opposing sidewall portions separated from one another by two intervening sidewall indentations; and, a wristpin bore extending between the sidewall indentations, wherein the crown and the skirt part are formed separately of compatible materials and are joined by welding or brazing. ### Claim 2 (depends on 1) The piston of claim 1, wherein the sidewall portions extend from the crown to the open end of the skirt, and the indentations run longitudinally in the sidewall between the first ring grooves and the second ring grooves. ### Claim 3 (depends on 1) The piston of claim 1, in which the skirt part has an interior wall near a first end of the sidewall and the annular cooling gallery is defined between a first side of the interior wall and an under surface of the crown. ### Claim 4 (depends on 3) The piston of claim 3, in which a second side of the interior wall opposite the first side includes at least a portion of a wristpin bore. ### Claim 5 (depends on 1, 2, 3, 4) The piston of any one of claims 1-4, comprising a wristpin received in the wristpin bore. ### Claim 6 (depends on 5) The piston of claim 5, in which the wristpin comprises a biaxial bearing unit. ### Claim 7 (depends on 6) The piston of claim 6, in which the biaxial bearing unit comprises a bearing sleeve received in the wristpin bore and a wristpin journal supported by the bearing sleeve for oscillatory rocking during operation of the opposed-piston engine. ### Claim 8 A piston for an opposed-piston engine, the piston having a longitudinal axis and comprising: a crown with an end surface shaped to define a combustion chamber with an end surface of an opposing piston in an opposed-piston engine; a separate skirt part joined to the crown; the crown including first ring grooves; the skirt part including second ring grooves spaced apart from the first ring grooves along the longitudinal axis; the skirt part including a piston sidewall with opposing sidewall portions separated from one another by intervening sidewall indentations running along the longitudinal axis between the first and second ring grooves; an annular cooling gallery within the piston; a wristpin bore extending between the sidewall indentations, wherein the crown and the skirt part are formed separately of compatible materials and are joined by welding or brazing. ### Claim 9 (depends on 8) The piston of claim 8, wherein the sidewall portions extend from the crown to an open end of the skirt. ### Claim 10 (depends on 8) The piston of claim 8, in which the skirt part has an interior wall near a first end of the sidewall and the annular cooling gallery is defined between a first side of the interior wall and an under surface of the crown. ### Claim 11 (depends on 10) The piston of claim 10, in which a second side of the interior wall opposite the first side includes at least a portion of a wristpin bore. ### Claim 12 (depends on 8, 9, 10, 11) The piston of any one of claims 8-11, comprising a wristpin received in the wristpin bore. ### Claim 13 (depends on 12) The piston of claim 12, in which the wristpin comprises a biaxial bearing unit. ### Claim 14 (depends on 13) The piston of claim 13, in which the biaxial bearing unit comprises a bearing sleeve received in the wristpin bore and a wristpin journal supported by the bearing sleeve for oscillatory rocking during operation of the opposed-piston engine.