Hydrodynamic seal

In combination with a sealing surface of circular cross-sectional configuration and a component located generally around the surface and arranged such that relative rotation about an axis of rotation may occur between the sealing surface and the component, an improved seal for isolating within the component a region that contains a lubricant, said seal comprising:

• a generally rigid case attached to the component such that a static seal exists between the component and the case and a sealing element attached to the case and encircling the sealing surface, the sealing element including a primary lip presented toward the isolated region and a secondary lip presented away from the isolated region, the primary lip having a circumferential face which is presented toward and encircles the sealing surface, but is spaced from the sealing surface, and a first end face which is presented at a substantial angle with respect to the circumferential face and is presented toward and exposed to the isolated region, the circumferential face and the first end face merging at an edge, the primary lip further having pumping cavities which open out of the circumferential and first end faces through the edge at which those faces merge so that the edge is interrupted by the cavities, each cavity having side faces which diverge toward the first end face and are oblique to the direction of relative rotation between the sealing surface and the component which is generally around the sealing surface, so that a lubricant entering the cavity will be pumped back toward the isolated region irrespective of the direction of relative rotation, the secondary lip contacting the sealing surface for the full circumference of the sealing surface.

In combination with a sealing surface of circular cross-sectional configuration and a component located generally around the surface and arranged such that relative rotation about an axis of rotation may occur between the sealing surface and the component, an improved seal for isolating within the component a region that contains a lubricant, said seal comprising:

• a generally rigid case attached to the component and an elastomeric sealing element attached to the case and including a primary lip presented toward the isolated region and a secondary lip presented away from the isolated region, the primary lip having a first face which is presented toward and encircles the sealing surface, generally following the contour thereof both axially and circumferentiall, but is spaced from the sealing surface, and a second face which is located at an angle with respect to the first face and is presented toward and exposed to the isolated region, the primary lip further having pumping cavities which open out of both the first and second faces and are defined by cavity faces some of which are oblique to the direction of relative rotation between the sealing surface and encircling component and at least one of which is oblique to the axis of rotation such that the portion of the cavity located at the second face extends further outwardly from the axis of rotation and is wider than the portion that is remote from the second face, whereby lubricant upon entering any cavity will be pumped back toward the isolated region and directed generally outwardly away from the axis of rotation as a result of the relative rotation, the secondary lip contacting the sealing surface for the full circumference of the sealing surface and being oriented generally obliquely with respect to the sealing surface such that an increase in pressure within the isolated region will cause the secondary lip to separate from the sealing surface and vent the isolated region.

In combination with a tapered roller bearing including a cup having an inwardly presented tapered raceway and a counterbore located as the large end of the raceway, a cone having an outwardly presented raceway that is presented toward and surrounded by the raceway of the cup and a thrust rib located at and projecting radially beyond the large end of the cone raceway, the thrust rib having a sealing surface that is located generally within the counterbore of the cup, tapered rollers located in the space between and contacting the raceways of the cup and con to enable relative rotation between the cupand cone to occur about an axis of rotation, and a lubricant in the space between the cup and cone, a improved seal for isolating the space between the cup and cone and for retaining the lubricant in that space, said seal comprising:

• a relatively rigid case fitted tightly into the counterbore of the cup so as to be fixed in position with repsect to the cup, and a sealing element attached to the seal case and having primary and secondary lips, the primary lip being located closest to the space isolated by the seal and including a first face presented toward and e circling the sealing surface of the thrust rib such that it generally follows the contour of the sealing surface both axially and circumferentially, but being for the most part spaced from the sealing surface so that a clearance exists between tne first face and the sealing surface, the primary lip also having pumping cavities which open out of the first face toward the sealing surface and also open toward the tapered rollers, the pumping cavities intersecting the first face along lines that are oblique to a plane that is perpendicular to the axis of rotation, with the lines being oriented such that the pupping cavities by reason of relative rotation between the cup and cone deflect lubricant that enters the cavities back toward the tapered rollers irrespective of the direction of relative rotation between the cup and cone, each pumping cavity also being generally wedge-shaped in a plane that intersects it and contains the axis of rotation such that the pumping cavity extends farthest away from the axis of rotation where it opens toward the rollers, so that the cavities deflect the lubricant away from the sealing surface under the centrifugal force generated by the rotation;
• the secondary lip being located further from the tapered rollers than the primary lip and being in contact with the sealing surface for the full circumference of the sealing surface.

A seal for isolating a region between machine components which rotate relative to each about an axis of rotation;

• said seal comprising:
• a generally rigid case, and an elastomeric sealing element bonded to the case and including a primary lip and a secondary lip spaced axially from the primary lip, the primary lip having a circumferential face which is presented toward the axis of rotation and spaced apart inner and outer end faces which are oriented at substantial angles with respect to the circumferential face and merge with the circumferential face along spaced apart edges, the primary lip having pumping cavities which open out of the circumferential and inner end faces througn the edge at which those faces merge so that the cavities interrupt the edge, each cavity being defined by faces which intersect the circumferential face at lines that diverge toward the edge between the circumferential face and inner end face and are oblique to the direction of relative rotation so that lubricant entering the pumping cavity will be deflected generally axially by virtue of relative rotation between the seal and a surface that it encircles irrespective of the direction of relative rotation, each pumping cavity also being defined by at least one face which diverges from the axis of rotation toward the inner end face so that lubricant entering the cavity is also deflected outwardly under the influence of centrifugal force as the lubricant moves axially through the cavity toward the inner end face, the secondary lip being spaced from the inner end face of the primary lip so that an annular space exists between the two lips, the secondary lip projecting inwardly toward the axis of rotation beyond the primary lip, with its least diameter being less than the diameter of the circumferential face for the primary lip.