Automotive wheel bearings and the seals which protect them have diminished in size over the years. Better steels have made smaller bearings possible, whereas improved seal designs reduced the size of the seals. The smaller bearings and seals left room for additional components, such as rotors and sensors for antilock braking systems and constant velocity joints. Installing the seals in the bearings themselves instead of in the hubs or housings that contain the bearings produced a further reduction in size. This practice contributed to the wide-spread use of unitary or package bearings.

But the diminished size of the seals and the spaces in which they are installed leaves less surface area for effecting fluid barriers. Where the bearings may be exposed to severe operating conditions, such as on light trucks and sport-utility vehicles, the seals should provide an extra measure of protection, and this generally requires that they provide multiple fluid barriers and that the fluid barriers remain effective for extended periods of time.

The present invention resides in a seal having an elastomeric seal element that closes an annular space between two machine components, one of which rotates relative to the other about an axis of rotation. One of the machine components carries axially directed and radially directed surfaces. The seal element has a mounting portion that is fixed in position with respect to the other machine component and a contact lip portion provided with radially and axially presented edges. The seal element contains a groove which opens away from the axis of rotation and generally separates the mounting portion from the contact lip portion. A resilient element fits into the groove, but does not bottom

out in the groove, and it acts upon the lip portion such that the axially presented edge is urged against the radially directed surface and the radially presented edge is urged against the axially directed surface. The invention also consists in the parts and in the arrangements and combinations of parts hereinafter described and claimed.

Brief Description of Drawings In the accompanying drawings which form part of the specification and wherein like numerals and letters refer to like parts wherever they occur: Fig. 1 is a sectional view of a bearing fitted with a seal constructed in accordance with and embodying the present invention; Fig. 2 is an enlarged sectional view of the seal; Fig. 3 is a fragmentary sectional view of the seal taken along line 3-3 of Fig. 2; Fig. 4 is a sectional view of a modified seal; Fig. 5 is a sectional view of another modified seal; and Fig. 6 is a sectional view of still another modified seal.

Best Mode for Carrying Out the Invention Referring now to the drawings, a double row antifriction bearing A (Fig 1) at each of its end is closed by a seal B, thus confining a lubricant, which is normally grease, to the interior of the bearing A, and excluding contaminants, such as water and dust, from that interior. The bearing A fits between two machine components and enables one of those components to rotate relative to the other about an axis X with minimum frictional resistance. Actually, the seal B may fit between and close an annular space that exists between any two machine components, one of which rotates relative to the other, but the closure of an antifriction bearing represents the primary utility for the seal B, and in that sense the two machine components may be races of the bearing itself.

The bearing A, which is conventional, includes (Fig. 1) an outer race in the form of a double cup 2, an inner race in the form of two cones 4, and rolling elements in the form of tapered rollers 6 which lie in two rows between the cup 2 and the two cones 4 - there being a separate row around each cone 4. In addition, the bearing A has cages 8 which are integrated into the two rows of rollers 6 and serve to maintain the proper spacing between the rollers 6 as well as to retain the rollers 6 around the cones 4 when the cones 4 are withdrawn from the cup 2. The rollers 6 of the two rows contact the cup 2 and the cone 4 along opposed raceways 10, there being two raceways 10 on the cup 2 and a single raceway 10 on each cone 4. Basically, line contact exists between the side faces of the rollers 6 and the raceways 10.

The raceways 10 of the cup 2 taper downwardly toward each other, and hence their smallest diameters lie generally midway between the ends of the cup 2. At their large ends the cup raceways 10 merge into end bores 12 which open out of ends of the cup 2.

Each cone 4, in addition to its raceway 10, has a thrust rib 14 at the large diameter end of its raceway 10. The large ends of the tapered rollers 6 bear against the thrust rib 14, and indeed the thrust rib 14 prevents the rollers 6 from being expelled from the bearing A. The thrust rib 14 for each cone 4 has a cylindrical mounting surface 18 that is presented outwardly away from the axis X and ends at a back face 20 which is squared off with respect to the axis X.

The raceways 10 of the cup 2 and the cones 4 define an annular space 22 (Fig. 1) within the bearing A, and this space 22 opens out of the ends of the bearing A through the end bores 12 of the cup 2 and around the mounting surfaces 18 on the cone thrust ribs 14. In short, the end bores 12 and mounting surfaces 18 lie at the ends of the annular space 22.

The seals B close the ends of the annular space 22 (Fig. 1), and they retain the lubricant for the bearing A in the space 22 and exclude contaminants from it. Actually, the seals B fit into the end bores 12 of the cup 2 and around

the thrust ribs 14 of the cones 4, providing live or dynamic barriers in these regions.

Each seal B includes (Figs. 1 and 2) a case 26 which fits into the end bore 12 at that end of the bearing A closed by the seal B, another case or shield 28 which fits around the cone thrust rib 14 at the same end of the bearing B, a primary seal element 30 which is bonded to the case 26 and contacts the shield 28, establishing three dynamic barriers along the shield 28, and a secondary seal element 32 which is bonded to the shield 28 and establishes yet another dynamic fluid barrier along the case 26. Both of the seal elements 30 and 32 are molded from an elastomer and as such have a measure of resiliency. In addition, each seal B includes a garter spring 33 which acts upon the primary seal element 30 to ensure the effectiveness of two of the fluid barriers established by it.

The case 26 includes (Fig. 2) an axial wall 34 which fits within and along the end bore 12 in which the seal B is housed and a radial wall 36 which is directed radially inwardly from the axial wall 34. The diameter of the axial wall 34 slightly exceeds that of the end bore 12, so that an interference fit exists between the case 26 and the cylindrical surface of the end bore 12. Hence, one must press the case 26 into the end bore 12. Indeed, the case 26 is advanced through the bore 12 until the free end of its axial wall 34 lies flush with the end face of the cup 2. The interference fit creates a static fluid barrier between the case 26 and the cup 2. The radial wall 36, while being directed toward the cone thrust rib 14 which lies within the end bore 12, terminates short of that thrust rib 14, so that a space of moderate size exists between the inner end of the radial wall 34 and the mounting surface 18 on the thrust rib 14.

That mounting surface 18 serves to position and support the shield 28.

Like the case 26, the shield 28 includes (Fig. 2) an axial wall 38 and a radial wall 40. The axial wall 38 lies along the mounting surface 18 of the thrust rib 14, and indeed an interference fit exists between the two. That interference fit creates a static fluid barrier between the shield 28 and the cone 4. During

installation of the seal B in the bearing A, the axial wall 38 of the shield 28 is pressed over the mounting surface 18 of the cone thrust rib 14. The radial wall 40 projects outwardly from the axial wall 38 toward the axial wall 34 of the case 26 and obscures the radial wall 36 of the case 26. The radial wall 40 of the shield 28 forms the exposed end of the seal B and generally lies flush with the end of the cup 2 and the back face 20 of the cone 4. It is separated from the radial wall 36 of the case 26, and the space between the two radial walls 36 and 40 forms an annular cavity. At its opposite end the axial wall 38 of the shield 28 merges into a slight flange 42 which is directed radially outwardly slightly beyond the inner edge of the radial wall 36 on the case 26, so that the case 26 is captured between the ends of the shield 28.

In addition, the shield 28 has another axial wall 44 (Fig 2) which extends from the radial wall 40 at the periphery of that wall such that the axial wall 44 encircles the inner axial wall 38. The outer axial wall 44, however, lies within the axial wall 34 of the case 26, and it projects toward the radial wall 36 of the case 26, terminating short of it.

The primary seal element 30 is attached to the case 26 and includes a mounting portion 46 which is bonded to the radial wall 36 of case 26 on both faces of that wall as well as along the end edge of wall 36. The seal element 30 also includes a contact lip portion 48, which projects generally axially from mounting portion 46. The mounting portion 46 does not actually contact the shield 28, but even so, it creates a labyrinth which serves as a barrier to the movement of the bearing lubricant along the inner axial wall 38 of the shield 28.

The contact lip portion 48, on the other hand, actually contacts the shield 28 along both the inner axial wall 38 and the radial wall 40 and at those regions of contact establishes more dynamic fluid barriers.

The mounting portion 46 has an inner surface that is presented toward, yet spaced from the axial wall 38 of the shield 28. The spacing between the wall 38 and the inner surface 52 is small enough to create a labyrinth that serves as barrier to the movement of lubricant along the axial wall 38. Generally

speaking, the space between the inner surface 52 on the mounting portion 46 and the axial wall 38 of the shield should be between 0.005 and 0.030 inches to produce an effective labyrinth. The inner surface 52 ends at an edge which is presented toward the flange 42 on the shield 28. The labyrinth created by the inner surface 52 on the mounting portion 46 is enhanced by wedge-shaped cavities 54 (Figs. 2 & 3) that open out of the inner surface 52 and also out of the end of the mounting portion 46 toward the flange 42 on the shield 28. The cavities 54, being wedge-shaped, have surfaces that lie oblique to the direction of relative movement between the mounting portion 46 and the axial wall 38 of the shield 28, and as a consequence, grease which enters the cavities 54 is deflected back into the annular space 22 between the cup 2 and cone 4.

The contact lip portion 48 lies axially beyond the mounting portion 46 where the outer axial wall 44 of the shield 28 encircles it. It projects toward both the inner axial wall 38 and the radial wall 40 of the shield 28 and has edges 56 and 58 which contact those walls, the former the wall 38 and the latter the wall 40. To this end, the lip portion 48 has a slight curved inner face 60 which lies oblique to the axis and leads away from the inner surface 52 of the mounting portion 46. In addition, the lip portion 48 has an end face 62 which likewise lies oblique to the axis X, although at a greater angle. The end face 62 is presented toward the corner where the inner axial wall 38 and the radial wall 40 of the shield 28 meet. The lip portion 48 has another end face 64 which likewise lies oblique to the axis X, but is presented generally away from the axis X. The inner face 60 and end face 62 converge toward the edge 56 which bears against the inner axial wall 38 of the shield 28. The two end faces 62 and 64 converge toward the edge 58 which bears against the radial wall 36 of the shield 28.

The primary seal element 30 also has an annular groove 66 (Fig. 2) which opens away from the axis X and generally separates the mounting portion 46 from the lip portion 48. Indeed, it is in the region of the groove 66 that the seal element 30 has its smallest cross-section, and this imparts a good measure

of flexibility to the lip portion 48, enabling it to flex easily with respect to the mounting portion 46. The groove 66 has an oblique side face 70 that lies along the lip portion 48, a radial side face 72 that lies along the mounting portion 46, and a curved face 74 that joins the two side faces 70 and 72. The oblique side face 70 lies behind end face 62, but is oriented at a slightly lesser angle to the axis X. The radial side face 72 lies immediately beyond and parallel to the radial wall 36 of the case 26. The side faces 70 and 72 converge - indeed, toward the curved face 74 which joins them. The center of curvature for the curved face 74 is offset axially from the radial edge 56 toward the mounting portion 46.

The annular groove 66 receives the garter spring 33 which urges the contact lip portion 48 against both the inner axial wall 38 and the radial wall 40 of the shield 28. More specifically, the garter spring 33 lodges in the groove 66, but does not actually seat against the curved face 74 at the-bottom of the groove 66. It cannot inasmuch as its cross-sectional radius is somewhat greater than the radius of the curved face 74. Instead, the garter spring 33 bears against the radial side face 72 and the oblique side face 70 of the groove 66 with a void between the convolutions of the spring 33 and the curved face 74 of the groove 66. The spring 33 urges the contact lip portion 48 axially away from the radial wall 36 of the case 26 and also radially toward the axis X. It thus ensures that the contact lip portion 48 at its radial edge 56 remains against the axial wall 38 of the shield 28 and at its axial edge 58 remains against the radial wall 36 of the shield 28. Even so, the spring 33 has a positive offset R, meaning that the cross- sectional center around which its convolutions spiral is displaced laterally from the radial edge 56 toward the mounting portion 46.

The secondary seal element 32 is bonded to outer axial wall 44 of the shield 28 and establishes a dynamic fluid barrier along the axial wall 34 of the case 26 (Fig. 2). To this end, it is provided with a lip 80 which projects obliquely toward the axial wall 34 of the case 26 and contacts the inner surface of the axial wall 34 near the free end of that wall. As such the lip 80 projects

generally away from the radial wall 36 of the case 26. The secondary seal element 32 also extends along the free end of the outer axial wall 44 of the shield 28, it being bonded to wall 44 along this end edge as well. Here the seal element 32 has bumper segments 82 which project beyond the end of the wall 44 toward the radial wall 36 of the case 26. Indeed, the bumper segments 82 form an axial extension of the outer axial wall 44 on the shield 28. When the bumper segments 82 bear against the radial wall 36 of the case 26, the radial wall 40 of the shield 28 lies generally flush with the free end of the axial wall 34 for the case 26. Thus, the bumper segments 82 serve to axially position the shield 28 with respect to the case 26, and this ensures that the contact lip portion 48 assumes the correct position with respect to the radial wall 40 of the shield 28.

In the operation of the seal B, either the shield 28 rotates within the case 26 or the case 26 rotates around the shield 28, depending on whether the cup 2 or the cone 4 is the rotating component of the bearing A. In either event, grease within the annular space 22 that represents the interior of the bearing A will migrate toward and against the mounting portion 46, but the labyrinth created by the relatively small gap between the inner surface 52 of the mounting portion 46 and the axial wall 38 of the shield 28 retards further migration along the axial wall 38. Moreover, the wedge-shaped cavities 54 enable the mounting portion 46 to actually drive the grease back into the annular space 22. In this regard, the surfaces of the cavities 54 lie oblique to the direction of relative movement between the case 26 and shield 28 and deflect the grease generally axially into the annular space 22. So the labyrinth formed by the mounting portion 46 establishes the initial fluid barrier insofar as the grease is concerned.

Even so, when the bearing A is at rest, some grease will seep through the space between the mounting portion 46 and the axial wall 38 of the shield 28 and lubricate the radial edge 56 of the contact lip 48.

The contact lip portion 48 under the natural bias of the elastomer from which it is molded bears against the axial wall 38 of the shield 28 along the

radial edge 56 and also bears against the radial wall 40 along the axial edge 58.

The former creates a fluid barrier in the form of a radial lip seal, while the latter creates another fluid barrier in the form of a face seal. But face seals are more difficult to sustain with the natural bias of an elastomer than are radial seals.

The garter spring 33 urges the end of the contact lip portion 48 both axially away from the radial wall 36 of the case 26 and radially inwardly toward the axis X. As such it exerts a force that supplements the natural resiliency of the elastomer in maintaining the axial edge 58 against the radial wall 40 of the shield 28 and in maintaining the radial edge 56 against the inner axial wall 38 of the shield 28. The spring 33 bears against the oblique side face 70 of the groove 66 radially outwardly from the axial edge 58, so even if the elastomer looses some of its resiliency, the spring 33 will continue to urge the axial edge 58 against the radial wall 40 of the shield 28 and the radial edge 56 against the axial wall 38 as well. Were the spring 33 seated in the bottom of the groove 66, it would not be effective in biasing the axial edge 58 against the radial wall 40 of the shield 28 and its effectiveness in biasing the radial edge 56 against the axial wall 38 of the shield 28 would be diminished as well. Owing to the bias imparted by the spring 33, the lip portion 48 at its radial edge 56 and axial edge 58 remains in contact with the axial wall 38 and radial wall 40, respectively, of the shield 28, even after the lip portion 48 has experienced considerable wear in the region of the two edges 56 and 58. Thus, the lip portion 48 along the edges 56 and 58 establishes two more dynamic fluid barriers between the case 26 and shield 28.

The oblique lip 80 of the secondary seal element 32 establishes still another dynamic fluid barrier between the shield 28 and case 26. It serves primarily to exclude contaminants from the annular space 22 within the bearing A and is indeed exposed to the exterior of the bearing A where it is the first of the several fluid barriers contaminants must pass before reaching the annular space 22 within the bearing A. The bumper segments 82, while serving primarily to position the shield 28 in the proper axial location with respect to the

case 26, also function as a labyrinth and in that sense form yet another dynamic fluid barrier between the case 26 and the shield 28.

A modified seal C (Fig. 4) is quite similar to the seal B, in that it has a case 26, a shield 28, a primary seal element 30 and a secondary seal element 32.

While the primary seal element 30 possesses a mounting portion 46, having an inner surface 52 that is close to axial wall 38 of the shield 28, it does not contain pumping cavities 54 and thus lacks the capacity to pump grease toward the annular space 22 in which the tapered rollers 6 are located. Even so, the inner surface 52 of the mounting portion 46 creates a labyrinth along the axial wall 38 of the shield 28. Also, the shield 28 lacks an outer axial wall 44, but instead outwardly terminates at a free edge on the radial wall 40. The outer seal element 32 is bonded to the radial wall 40 in this region, and does not possess bumper segments 82. Owing to the absence of the pumping cavities 54, the primarily seal element 30 for the seal C in the region of its mounting portion 46 need not be as long as the mounting portion 46 for the seal B, and as a consequence, the seal C may be somewhat shorter than the seal B, that is to say it may be manufactured with a lesser axial dimension.

Another modified seal D (Fig. 5) is likewise quite similar to the seal B.

As such, it includes a case 26, a shield 28 and a elastomeric seal element 30. It does not have a secondary seal element 32. Instead, the outer axial wall 44 of the shield 28 is formed out-of-round or eccentric to the inner axial wall 38 and to the axial wall 34 of the case 26 as well. The out-of-round or eccentric character of the outer axial wall 44 enables it to pump contaminants, primarily water, both into and out of the space generally enclosed by the case 26 and shield 28. The water that is pumped into the space eventually fills it. The first seal barrier formed along the axial edge 58 of the contact lip 48 prevents the water from advancing further through the seal D, and all water which encounters the seal afterwards is simply directed away. When the bearing A comes to rest, the water held in the space between the case 26 and shield 28 drains from that space. The construction and operation of a seal with an out-of-round or

eccentric outer axial wall 44 on its shield 28 are explained in greater detail in U.S. Patent Application 08/719,723 filed September 25, 1996 for the invention of Dennis L. Otto entitled Seal with Pumping Capabilities.

The seal element 30 for the seal D resembles the seal element 30 for the seal B, and in addition includes a rib 84 which projects from the radial wall 36 of the case 26 and lies within the outer axial wall 44 of the shield 28. It serves to create a labyrinth and in that sense establishes another dynamic barrier for contaminants. But the rib 84 may be omitted to reduce the radial dimension of the seal D.

Still another modified seal E (Fig. 6) closely resembles the seal C, except that the primary seal element 30 in its lip portion 48 has distinct contact lips 86 and 88. The lip 86 projects radially toward the axial wall 38 of the shield 28 and the radial edge 56 exists on it. Here the lip 86 actually contacts the axial wall 38 of the shield 28. The lip 88 projects axially toward the radial wall 40 and carries the edge 58 along which it contacts the radial wall 40. The groove 66 in the seal element 30 of the seal positions the spring 33 that it retains such that the spring 33 has a positive offset R and also such that the spring 33 bears against the side faces 70 and 72 of the groove 66 radially outwardly from axial edge 58 on the axial lip 88.

The garter spring 33 is conventional and as such constitutes a wire wound into convolutions and joined together at its ends so that the spring 33 assumes a circular configuration. It may be expanded to greater diameters, but always seeks to revert to its smallest diameter. Other resilient elements. may be used in lieu of the spring 33. For example, a resilient band formed from an elastomer may be substituted for the spring 33.

This invention is intended to cover all changes and modifications of the example of the invention herein chosen for purposes of the disclosure which do not constitute departures from the spirit and scope of the invention.