# US 2017/0284544 A1 · Piston with variable depth groove root > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0284544 A1 - Document ID: US20170284544A1 - Status: Published application - Kind: A1 - Application number: 15/084,850 - Filed: 2016-03-30 - Published: 2017-10-05 - Earliest claimed: 2016-03-30 - Assignees: Electro-Motive Diesel, Inc. - Applicants: Electro-Motive Diesel, Inc. - Inventors: Panchangam Nivarthi Amar Jeetendra - Web page: https://patentgrep.com/patent/US20170284544A1 ## CPC - F16J 1/09: with means for guiding fluids (F16J1/08 takes precedence) - F16J 9/12: Details - F02F 3/10: having surface coverings (F02F3/02 takes precedence) - F16J 9/00: Piston-rings {, e.g. non-metallic piston-rings}, seats therefor; Ring sealings of similar construction (other sealings between pistons and cylinders F16J3/06, F16J15/16 {; manufacture of piston-rings B23P15/06, B23P15/08}; tools for mounting or removing piston-rings or the like B25B; piston sealing arrangements on brake master cylinders B60T11/236 {; sealing provided on pump pistons F04B53/143}) - F16J 9/10: Special members for adjusting the rings - F16J 9/203: {Oil-scraping rings} - F16J: PISTONS {(specially adapted for dampers F16F9/32)}; CYLINDERS; SEALINGS - F02F: CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES ## Abstract A piston for an internal combustion engine includes a cylindrical piston body defining a longitudinal axis and having a top end and an outer cylindrical surface. A first piston ring groove is formed in the outer cylindrical surface and includes a groove root, an upper surface and a lower surface. The groove root has a variable depth about a circumference of the cylindrical piston body. ## Claims ### Claim 1 A piston for an internal combustion engine, comprising: a cylindrical piston body defining a longitudinal axis and having a top end and an outer cylindrical surface; and a first piston ring groove formed in the outer cylindrical surface, wherein the first piston ring groove includes a groove root, an upper surface and a lower surface; wherein the groove root has a variable depth about a circumference of the cylindrical piston body. ### Claim 2 (depends on 1) The piston of claim 1, wherein a depth of the groove root is greater at areas around the circumference corresponding to identified areas of liner and piston ring non-conformance. ### Claim 3 (depends on 2) The piston of claim 2, wherein the identified areas of liner and piston ring non-conformance correspond to areas of liner distortion. ### Claim 4 (depends on 2) The piston of claim 2, further including a second piston ring groove formed in the outer cylindrical surface and spaced along the longitudinal axis from the first piston ring groove. ### Claim 5 (depends on 4) The piston of claim 4, wherein the first piston ring groove is positioned closer to the top end of the cylindrical piston body than the second piston ring groove. ### Claim 6 (depends on 1) The piston of claim 1, wherein the upper surface and the lower surface are substantially parallel. ### Claim 7 A piston assembly for an internal combustion engine, comprising: a piston having a cylindrical piston body and having a top end and an outer cylindrical surface, a first piston ring groove formed in the outer cylindrical surface, wherein the first piston ring groove includes a groove root, an upper surface and a lower surface; a piston ring at least partially received within the first piston ring groove; and a cylinder liner receiving the piston and having an inner surface; wherein the groove root has a variable depth about a circumference of the cylindrical piston body. ### Claim 8 (depends on 7) The piston assembly of claim 7, wherein the inner surface of the cylinder liner has identified areas of liner and piston ring non-conformance; and wherein a depth of the groove root is greater at areas around the circumference corresponding to the identified areas of liner and piston ring non-conformance. ### Claim 9 (depends on 8) The piston assembly of claim 8, wherein the identified areas of liner and piston ring non-conformance correspond to areas of liner distortion. ### Claim 10 (depends on 8) The piston assembly of claim 8, wherein the upper surface and the lower surface are substantially parallel. ### Claim 11 (depends on 7) The piston assembly of claim 7, wherein the piston ring is substantially cylindrical. ### Claim 12 (depends on 7) The piston assembly of claim 7, wherein areas of greater depth of the groove root about the circumference of the cylindrical piston body define areas of higher gas flow between the piston ring and the groove root relative to remaining areas of the groove root. ### Claim 13 (depends on 12) The piston assembly of claim 12, further including a second piston ring groove formed in the outer cylindrical surface. ### Claim 14 (depends on 13) The piston assembly of claim 13, wherein the first piston ring groove is positioned closer to the top end of the cylindrical piston body than the second piston ring groove. ### Claim 15 A method of manufacturing a piston for an internal combustion engine, wherein the piston includes a cylindrical piston body and has a top end and an outer cylindrical surface, the method comprising steps of: determining identified areas of liner and piston ring non-conformance along an internal surface of a cylinder liner; and forming a first piston ring groove in the outer cylindrical surface having a variable depth groove root, varying about a circumference of the cylindrical piston body at areas corresponding to the identified areas of liner and piston ring non-conformance ### Claim 16 (depends on 15) The method of claim 15, wherein the determining step includes identifying areas of liner distortion. ### Claim 17 (depends on 15) The method of claim 15, further including forming a second piston ring groove in the outer cylindrical surface. ### Claim 18 (depends on 17) The method of claim 17, further including positioning the first piston ring groove closer to the top end than the second piston ring groove.