# US 2021/0340890 A1 · Stem seal for valve assembly of machine engine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0340890 A1 - Document ID: US20210340890A1 - Status: Published application - Kind: A1 - Application number: 16/866,095 - Filed: 2020-05-04 - Published: 2021-11-04 - Earliest claimed: 2020-05-04 - Assignees: Caterpillar Inc. - Applicants: Caterpillar Inc. - Inventors: Ashwin A. Hattiangadi; Selvaganapathi Ganesan; Jakub M. Walczak - Web page: https://patentgrep.com/patent/US20210340890A1 ## CPC - F01L 3/08: Valves guides; Sealing of valve stem, e.g. sealing by lubricant - F01L 1/146: {Push-rods} - F01L 1/181: {Centre pivot rocking arms} - F01L 1/462: {Valve return spring arrangements} - F01L 3/20: Shapes or constructions of valve members, not provided for in preceding subgroups of this group - F02F 1/24: Cylinder heads - F16K 41/04: with at least one ring of rubber or like material between spindle and housing - F01L 2001/054: {Camshafts in cylinder block} - F01L 2003/25: {Valve configurations in relation to engine} - F01L 2820/01: Absolute values - F02F 2001/244: {Arrangement of valve stems in cylinder heads} - F01L: CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES - F02F: CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES - F16K: VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING {(devices for emptying and evacuating the excess liquid in valves or conduits F16L55/07)} ## Abstract A valve assembly for an engine includes a gas exchange valve, a valve guide, and a seal. The gas exchange valve includes a valve stem. The valve guide includes an outer surface having a stem seal retention surface disposed at a seal end thereof. The valve stem extends through the valve guide such that the valve is reciprocally movable over a range of travel along the longitudinal axis with respect thereto. The seal is mounted to the stem seal retention surface of the valve guide such that the seal is in running, sealing engagement with the valve stem. The stem seal retention surface includes a shoulder surface to help retain the seal. ## Claims ### Claim 1 A valve guide for an engine, the valve guide comprising: a guide body with a mounting end and a seal end, the guide body being cylindrical and extending axially along a longitudinal axis between the mounting end and the seal end, the guide body including an inner surface and an outer surface, the inner surface defining a valve passage; wherein the outer surface includes a stem seal retention surface, the stem seal retention surface disposed at the seal end of the guide body, the stem seal retention surface including a distal face, an axial surface, and a shoulder surface, the distal face being annular and projecting radially outward from the inner surface, the axial surface having a face edge and a shoulder edge, the face edge adjacent the distal face, and the shoulder edge adjacent the shoulder surface, the axial surface extending axially from the face edge to the shoulder edge such that the shoulder edge is disposed radially outward of the face edge, and the shoulder surface including an inner end, the shoulder surface extending from the shoulder edge radially inwardly to the inner end such that the shoulder surface includes an engagement portion extending from the shoulder edge toward the inner end, the engagement portion having a shoulder slant angle relative to a radial plane perpendicular to the longitudinal axis, the shoulder slant angle being within fifteen degrees of the radial plane. ### Claim 2 (depends on 1) The valve guide according to claim 1, wherein the shoulder edge is disposed a radial edge distance from the inner surface of the guide body, and the engagement portion of the shoulder surface extends inwardly from the shoulder edge toward the inner surface over a radial rib engagement distance, and wherein a ratio of the radial rib engagement distance to the radial edge distance is at least 0.04. ### Claim 3 (depends on 1) The valve guide according to claim 1, wherein the shoulder slant angle of the engagement portion of the shoulder surface is within five degrees of the radial plane. ### Claim 4 (depends on 1) The valve guide according to claim 1, wherein the engagement portion of the shoulder surface is substantially planar and extends inwardly from the shoulder edge toward the inner surface over a radial rib engagement distance of at least 0.125 mm. ### Claim 5 (depends on 1) The valve guide according to claim 1, wherein the shoulder edge comprises a non-rounded intersection between the axial surface and the shoulder surface. ### Claim 6 (depends on 1) The valve guide according to claim 1, wherein the shoulder edge comprises an angled corner between the axial surface and the shoulder surface having a shoulder angle therebetween, the shoulder angle being in a range between 45 degrees and 95 degrees. ### Claim 7 (depends on 1) The valve guide according to claim 1, wherein the shoulder edge comprises an angled corner between the axial surface and the shoulder surface having a shoulder angle therebetween, the shoulder angle being in a range between 70 degrees and 92.5 degrees. ### Claim 8 (depends on 1) The valve guide according to claim 1, wherein the axial surface includes a first axial portion and a second axial portion, the first axial portion including the face edge, the second axial portion including the shoulder edge, the first axial portion having a first axial slant angle relative to the radial plane perpendicular to the longitudinal axis, the second axial portion having a second axial slant angle, the second axial slant angle being greater than the first axial slant angle. ### Claim 9 (depends on 8) The valve guide according to claim 8, wherein the second axial slant angle is in a first range between 75 and 90 degrees. ### Claim 10 (depends on 9) The valve guide according to claim 9, wherein the first axial slant angle is in a second range between 40 and 75 degrees, and the axial surface includes an intermediate edge, the first axial portion extending axially from the face edge to the intermediate edge, and the second axial portion extending from the intermediate edge to the shoulder edge. ### Claim 11 (depends on 8) The valve guide according to claim 8, wherein the axial surface comprises a first axial surface, and wherein the stem seal retention surface includes a second axial surface, the second axial surface including an outer radial portion, the second axial surface extending axially from the inner end of the shoulder surface toward the mounting end to the outer radial portion such that the outer radial portion is disposed radially outward of the inner end. ### Claim 12 (depends on 11) The valve guide according to claim 11, wherein the stem seal retention surface includes a proximal seat surface, the proximal seat surface being annular and projecting radially outward from the second axial surface. ### Claim 13 A cylinder head for an engine, the cylinder head comprising: a cylinder head body, the cylinder head body defining a guide passage; a valve guide, at least a portion of the valve guide disposed within the guide passage, the valve guide including a guide body with a mounting end and a seal end, the guide body being cylindrical and extending axially along a longitudinal axis between the mounting end and the seal end, the guide body including an inner surface and an outer surface, the inner surface defining a valve passage, wherein the outer surface includes a stem seal retention surface, the stem seal retention surface disposed at the seal end of the guide body, the stem seal retention surface including a distal face, an axial surface, and a shoulder surface, the distal face being annular and projecting radially outward from the inner surface, the axial surface having a face edge and a shoulder edge, the face edge adjacent the distal face, and the shoulder edge adjacent the shoulder surface, the axial surface extending axially from the face edge to the shoulder edge such that the shoulder edge is disposed radially outward of the face edge, and the shoulder surface including an inner end, the shoulder surface extending from the shoulder edge radially inwardly to the inner end such that the shoulder surface includes an engagement portion extending from the shoulder edge toward the inner end, the engagement portion having a shoulder slant angle relative to a radial plane perpendicular to the longitudinal axis, the shoulder slant angle being within fifteen degrees of the radial plane. ### Claim 14 (depends on 13) The cylinder head according to claim 13, the cylinder head body defining a fluid passage having a port in fluid communication therewith, the cylinder head further comprising: a valve seat, the valve seat disposed within the port. ### Claim 15 (depends on 14) The cylinder head according to claim 14, wherein the shoulder edge of the valve guide comprises an angled corner between the axial surface and the shoulder surface having a shoulder angle therebetween, the shoulder angle being in a range between 45 degrees and 95 degrees, wherein the axial surface includes a first axial portion and a second axial portion, the first axial portion including the face edge, the second axial portion including the shoulder edge, the first axial portion having a first axial slant angle relative to the radial plane perpendicular to the longitudinal axis, the second axial portion having a second axial slant angle, the second axial slant angle being greater than the first axial slant angle. ### Claim 16 A valve assembly for an engine, the valve assembly comprising: a valve, the valve including a tip, a stem, and a head, the stem extending axially along a longitudinal axis and interposed between the tip and the head; a valve guide, the valve guide including a guide body with a mounting end and a seal end, the guide body being cylindrical and extending axially along the longitudinal axis between the mounting end and the seal end, the guide body including an inner surface and an outer surface, the inner surface defining a valve passage extending longitudinally between the seal end and the mounting end, and the outer surface includes a stem seal retention surface disposed at the seal end of the guide body, the stem of the valve extending through the valve passage such that the valve is reciprocally movable over a range of travel along the longitudinal axis with respect to the valve guide; a seal, the seal being hollow and extending along the longitudinal axis, the seal including a mounting portion and a valve stem sealing portion, the mounting portion defining a valve guide cavity extending along the longitudinal axis and being retentively engaged with the stem seal retention surface of the valve guide such that the seal end of the valve guide is disposed within the valve guide cavity, the mounting portion including an annular retention rib projecting radially inwardly into the valve guide cavity, the valve stem sealing portion defining a valve stem passage extending along the longitudinal axis and in communication with the valve guide cavity, the stem of the valve extending through the valve stem passage such that the valve stem sealing portion is in sliding, sealing engagement therewith; wherein the stem seal retention surface of the valve guide includes a distal face, an axial surface, and a shoulder surface, the distal face being annular and projecting radially outward from the inner surface of the valve guide, the axial surface having a face edge and a shoulder edge, the face edge adjacent the distal face, and the shoulder edge adjacent the shoulder surface, the axial surface extending axially from the face edge to the shoulder edge such that the shoulder edge is disposed radially outward of the face edge, and the shoulder surface including an inner end, the shoulder surface extending from the shoulder edge radially inwardly to the inner end such that the shoulder surface includes an engagement portion extending from the shoulder edge toward the inner end, the engagement portion having a shoulder slant angle relative to a radial plane perpendicular to the longitudinal axis, the shoulder slant angle being within fifteen degrees of the radial plane, the engagement portion in retentive, interfering relationship with the annular retention rib of the seal. ### Claim 17 (depends on 16) The valve assembly according to claim 16, wherein the seal comprises a double gas lip seal. ### Claim 18 (depends on 16) The valve assembly according to claim 16, wherein the shoulder edge is disposed at a radial position, the engagement portion of the shoulder surface extends inwardly from the shoulder edge toward the inner surface over a radial engagement distance, and wherein the annular retention rib, in an uncompressed condition, extends radially inwardly beyond the radial position by a retention distance at least twice as great as the radial engagement distance. ### Claim 19 (depends on 16) The valve assembly according to claim 16, wherein the seal has an axial seal length, the valve guide has a valve guide diameter, and a ratio of the axial seal length to the valve guide diameter is less than 1. ### Claim 20 (depends on 16) The valve assembly according to claim 16, further comprising: a valve spring, the valve spring mounted to the tip of the valve, the valve spring configured to bias the valve relative to the valve guide to a closed position.