Stem seal for valve assembly of machine engine

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.

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.