# US 8,770,090 B2 · Methods and systems for managing a clearance gap in a piston engine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,770,090 B2 - Document ID: US8770090B2 - Status: Granted - Kind: B2 - Application number: 13/725,984 - Filed: 2012-12-21 - Published: 2013-07-04 - Granted: 2014-07-08 - Earliest claimed: 2011-12-29 - Assignees: EtaGen, Inc. - Applicants: Etagen, Inc. - Inventors: John Lawler; Matt Svrcek - Web page: https://patentgrep.com/patent/US8770090B2 ## CPC - F02F 1/00: Cylinders; Cylinder heads - F16J 1/02: Bearing surfaces - F16J 1/09: with means for guiding fluids (F16J1/08 takes precedence) - F16J 10/02: Cylinders designed to receive moving pistons or plungers - F02F 1/004: {Cylinder liners (F02F1/08, F02F1/16 take precedence)} - F02F 3/00: Pistons - F02F: CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES - F16J: PISTONS {(specially adapted for dampers F16F9/32)}; CYLINDERS; SEALINGS ## Abstract A piston engine may include a non-contact bearing between a piston assembly and a cylinder. The piston may be configured to translate in a bore of the cylinder, and a non-contact bearing may be included in a clearance gap between the piston assembly and the bore. A bearing fluid may be supplied to the clearance gap via the piston assembly and/or cylinder to create the non-contact bearing. A bearing element may be used to direct or otherwise manage the flow of bearing fluid in the clearance gap. The bearing element may include one or more holes, porous portions, and/or passages to direct the bearing fluid to the clearance gap. ## Claims ### Claim 1 An assembly comprising: a cylinder comprising a bore and a section capable of containing a fluid; a piston assembly capable of translating axially along an axis of the bore, wherein the piston assembly comprises a piston face; at least one bearing element affixed to the piston assembly and configured to provide a flow of a bearing fluid into a clearance gap formed between the piston assembly and the cylinder, wherein the bearing fluid is comprised of a gaseous bearing fluid; and at least one or more passages configured to route blow-by gas away from a portion of the clearance gap adjacent to the bearing element. ### Claim 2 (depends on 1) The assembly of claim 1, wherein the piston assembly further comprises a feed passage configured to receive the bearing fluid from a fluid source and to provide the bearing fluid to the bearing element. ### Claim 3 (depends on 2) The assembly of claim 2, wherein the bearing element comprises a porous annular element that allows the bearing fluid to flow radially outward through pores from the feed passage to the clearance gap. ### Claim 4 (depends on 2) The assembly of claim 2, wherein the bearing element comprises one or more radial holes configured to allow the bearing fluid to flow radially outward from the feed passage to the clearance gap. ### Claim 5 (depends on 1) The assembly of claim 1, wherein the bearing element comprises at least one of a graphite element, a metal element with machined features, a sintered metal element, a porous ceramic element, and a nonporous ceramic element. ### Claim 6 (depends on 1) The assembly of claim 1, wherein the bearing fluid comprises air. ### Claim 7 (depends on 1) The assembly of claim 1, wherein the fluid contained in the section comprises a gas, and wherein the piston assembly further comprises a feature or component that aids in centering the piston assembly about an axis of the bore using a flow of blow-by gas from the section. ### Claim 8 (depends on 1) The assembly of claim 1, wherein the fluid contained in the section comprises a gas. ### Claim 9 (depends on 1) The assembly of claim 1, wherein the fluid contained in the section comprises a gas, and wherein the piston assembly further comprises a labyrinth seal configured to affect a flow of blow-by gas. ### Claim 10 (depends on 9) The assembly of claim 9, wherein the labyrinth seal comprises a plurality of circumferential grooves. ### Claim 11 (depends on 1) The assembly of claim 1, wherein the flow of the bearing fluid is configured to form a fluid layer in the clearance gap. ### Claim 12 (depends on 11) The assembly of claim 11, wherein the fluid layer aids in centering the piston assembly about an axis of the bore. ### Claim 13 (depends on 1) The assembly of claim 1, wherein the section comprises at least one of a combustion section and a gas driver section, and wherein the piston face is configured to contact the section. ### Claim 14 (depends on 1) The assembly of claim 1, wherein the assembly is configured for oil-less operation. ### Claim 15 An assembly configured to translate axially along an axis of a cylinder comprising a section capable of containing a fluid, the assembly comprising: a piston face configured to contact the section; at least one bearing element affixed to the assembly and configured to provide an outward flow of a bearing fluid to a surface of the assembly, wherein the assembly does not contact the cylinder; and at least one or more passages configured to route blow-by gas from the section away from the bearing element. ### Claim 16 (depends on 15) The assembly of claim 15, further comprising a feed passage, wherein the feed passage is configured to receive the bearing fluid from a fluid source and to provide the bearing fluid to the bearing element. ### Claim 17 (depends on 16) The assembly of claim 16, wherein the bearing element comprises a porous annular element that allows the bearing fluid to flow radially outward through pores from the feed passage to the surface of the assembly. ### Claim 18 (depends on 16) The assembly of claim 16, wherein the bearing element comprises one or more radial holes configured to allow the bearing fluid to flow radially outward from the feed passage to the surface of the assembly. ### Claim 19 (depends on 15) The assembly of claim 15, wherein the fluid contained in the section comprises a gas, the piston assembly further comprising a feature that aids in centering the piston assembly about an axis of the cylinder using a flow of blow-by gas from the section. ### Claim 20 (depends on 15) The assembly of claim 15, wherein the fluid contained in the section comprises a gas, the assembly further comprising a labyrinth seal configured to affect a flow of blow-by gas. ### Claim 21 (depends on 15) The assembly of claim 15, wherein the fluid contained in the section comprises a gas. ### Claim 22 (depends on 15) The assembly of claim 15, wherein the bearing fluid comprises air. ### Claim 23 (depends on 15) The assembly of claim 15, wherein the section comprises at least one of a combustion section and a gas driver section, and wherein the piston face is configured to contact the section. ### Claim 24 (depends on 15) The assembly of claim 15, wherein the assembly is configured for oil-less operation. ### Claim 25 A cylinder of a piston engine, the cylinder comprising: a bore capable of housing a piston movable along an axis of the bore; at least one bearing element configured to provide a flow of a bearing fluid to the bore, wherein the piston does not contact the cylinder; and a feed passage configured to receive the bearing fluid from a fluid source and provide the bearing fluid to the bearing element, wherein the bearing element comprises a porous annular element configured to allow the bearing fluid to flow radially inward through pores from the feed passage to the bore. ### Claim 26 (depends on 25) The cylinder of claim 25, wherein the bearing element further comprises one or more radial holes configured to allow the bearing fluid to flow radially inward from the feed passage to the bore. ### Claim 27 (depends on 25) The cylinder of claim 25, wherein the cylinder is configured for oil-less operation. ### Claim 28 (depends on 1) The assembly of claim 1, further comprising a seal affecting a flow of the blow-by gas. ### Claim 29 (depends on 15) The assembly of claim 15, further comprising a seal affecting a flow of the blow-by gas.