Bearing With Multiple Lip Seal

This invention relates to seals and sealed bearings. More particularly, this invention is a new and improved labyrinth seal and a bearing containing the seal.

Our new bearing comprises a housing or outer race with an axial bore and a rotatable shaft or inner race of less diameter than the diameter of the bore mounted in the housing. The annular bearing space thus provided between housing and shaft in part contains a lubricant.

An annular seal is located in the annular space and includes an annular main body portion, an annular axially inner lip, and at least one annular lip axially spaced from the inner lip. The main body portion may contain a stiffening insert. At least one opening is provided in the inner lip with the opening extending from the annular bearing space containing the lubricant, through the lip and into the annular seal space provided by the two axially spaced lips. In preferred two-lip seal modifications an opening is also provided in the outer annular lip. The opening in the outer annular lip is preferably circumferentially spaced approximately 180.degree. from the opening in the inner annular lip, thus forming a labyrinth passageway through the seal. In two-lip designs in which the inner lip has two or more circumferentially spaced openings, the openings in the outer lip would preferably be circumferentially spaced midway between the openings in the inner lip. In three-lip seal modifications with one opening in each seal, the openings in the inner lip and the outer lip may be aligned, and the opening in the middle lip circumferentially spaced approximately 180.degree. from the aligned openings, thus forming an even longer labyrinth passageway through the seals.

The openings in the annular lips may be holes through the sealing lips or may be notches through the lips adjacent the lip-contacting surface of the shaft or housing. If desired, the openings in one lip may be holes while the openings in the other lip are notches. The notches or holes relieve the pressure inside the bearing and seal when lubricant is forced inside and allow easy lubricant flow over the entire annular seal space between the sealing lips which form the labyrinth guard against intrusion of contaminates. The lubricant within the seal cooperates with the labyrinth seal to form an even better barrier to contaminates.

The invention may be further understood by the following detailed description and drawings in which:

FIG. 1 is an elevational, sectional view illustrating one embodiment of our invention;

FIG. 2 is an elevational, sectional view illustrating a second embodiment of our invention;

FIG. 3 is an elevational, sectional view illustrating a third embodiment of our invention;

FIG. 4 is an elevational, sectional view showing a fourth embodiment of our invention; and

FIG. 5 is an elevational, sectional view showing still another embodiment of our invention.

In the various figures, like parts are referred to by like numbers.

Our new bearing includes a housing or outer race or outer ring 10 with an axial bore 12 and a rotatable shaft or inner race or inner ring 14. The diameter of the rotatable shaft is less than the diameter of the bore in the housing thereby providing an annular bearing space 15 which contains lubricant. A circumferential groove 16 of greater diameter than the bore 12 may be provided in the housing. There may also be a counter-bore 18 with diameter greater than bore 12 and less than groove 16. The diameter of counter-bore 18 in housing 10 is such that the annular seal 20 may be fitted in place by pressing the annular seal 20 into the counter-bore 18 and locating the annular seal within the groove 16. It is also possible to press fit the seal, preferably including a stiffening member, in the housing bore.

The annular seal 20 includes an annular main body portion 22, an annular inner lip 24, and an annular outer lip 26. The annular lips 24 and 26 are axially spaced apart and are in wiping contact with the shaft 14.

In the embodiment shown in FIG. 1, at least one opening, such as the axially extending notch 28 adjacent shaft 14, extends through the annular lip 24 from the annular bearing space 15 to the annular seal space 30 provided by the axially spaced lips 24 and 26.

The outer annular lip 26 also contains at least one opening such as notch 32 extending axially adjacent the shaft 14. The notch 28 in the annular lip 24 and notch 32 in annular lip 26 are circumferentially spaced from one another. Preferably the circumferential spacing is approximately 180.degree., thus providing the longest possible labyrinth passageway past the seal to keep out foreign matter while maintaining an opening to balance the fluid pressure from one side of the seal to the other.

When lubricant is forced into the annular space 15, or when a temperature change tends to change the interior pressure or when the exterior pressure is changed as by an airplane utilizing the bearing changing altitude, and the relative pressure changes in said annular space, the notch 28 provides a purging opening to relieve the pressure differential which may otherwise act to dislodge the seal 20 from its intended position in the bearing. The notch 28 allows lubricant to enter and fill the cavity 30 between the seal lips 24 and 26. This forms a torous of lubricant which acts to further seal and to trap external contaminate which might otherwise enter past the sealing lips. This lubricant torous also provides lubrication to the outer seal lip which can otherwise wear at a rapid rate if lubrication is not provided.

The approximate 180.degree. circumferential separation of notch 28 in annular lip 24, from notch 32 in annular lip 26 helps to completely fill the space 30 between the sealing lips. The pressurized lubricant enters the annular seal space 30 through the notch 28, then diverts circumferentially in each direction filling the space 30 and finally purging through notch 32.

For some operations, it may be desirable not to interrupt the sealing contact of the lips 24 and 26 against the shaft 14. In such cases, as shown in FIG. 2, a hole 33, instead of a notch, is formed through the annular lip 24 and extends from the annular bearing space 15 through lip 24 and into the annular seal space 30 formed by the lips 24 and 26. A hole 34 is also formed in annular lip 26 and extends through the annular lip 26 from the annular seal space 30 to the outside of the seal. The holes are spaced circumferentially 180.degree. apart. Where there are two or more holes in each lip, the holes in the second lip are spaced circumferentially midway between the holes in the first lip. The holes may be of any shape or alignment, and for ease of molding may be parallel to the seal axis.

In FIG. 3, the seal lips contact the housing rather than the shaft. As shown in FIG. 3, the shaft 40 is mounted for relative rotation within the housing 42 with the annular space 44 containing the lubricant. The annular seal 46 has its annular main body portion 48 located within an annular groove 43 formed in the shaft 40. Axially spaced apart inner lip 50 and outer lip 52 are in wiping contact with the housing 42. An axially extending notch 54 adjacent housing 42 extends from annular bearing space 44 through lip 50 and into the annular seal space 56 provided by the axially spaced apart lips 50 and 52. An axially extending notch 58 in lip 52 extends adjacent the housing from the annular space 56 through lip 52 to the outside of the seal. Sometimes, instead of having a groove, the seal will be press fit onto the shaft. A preferred structure for such a press fit would include a stiffening member with the seal.

In the embodiment shown in FIG. 4, the shaft or inner race 14 is rotatably mounted within a housing or outer race 60 containing a counter-bore 62. The annular seal 64 includes a generally annular metal ring 66 with radially extending portions 68 and 70 in which is mounted a resilient member including main body portion 71, an annular axially inner lip 72, an annular middle lip 74 axially spaced from the inner lip 72, and an annular outer lip 76 axially spaced from annular middle lip 74. The notch 78 in inner lip 72 adjacent the shaft 14, extends from the bearing space 80 containing the lubricant through inner lip 72 and into the first annular seal space 82 formed by inner lip 72 and middle lip 74. A notch 84 is formed in the middle lip 74 and extends through the middle lip 74 from the first annular seal chamber 82 to second annular seal chamber 86 formed by the middle lip 74 and the outer lip 76. A notch 88 is formed in outer lip 76 and extends from the second seal space 86 through the outer lip 76 to the outside of the seal.

Notch 78 in inner lip 72 is circumferentially spaced from notch 84 in the adjacent middle lip 74 by an approximately 180.degree. angle; notch 88 in the outer lip 76 is circumferentially spaced from notch 84 in the adjacent middle lip 74 by an approximate 180.degree. angle. Therefore, notch 88 in outer lip 76 is substantially in line with notch 78 in the inner lip 72. When there are two or more notches in each lip, the notches in the middle lip are spaced circumferentially midway between the notches of the first lip, and the notches in the third lip would again be substantially in line with the notches in the first lip. Other spacing could be utilized if it were found desirable for a particular structure.

In the embodiment shown in FIG. 5, a labyrinth sealing member including the annular body portion 90 may be used where contacting lips are undesirable. Inner annular lip 92, middle annular lip 94, and the outer annular lip 96 are each slightly spaced from the shaft 14. The axially extending notch 98 adjacent shaft 14 is circumferentially spaced from the axially extending notch 100 in the annular middle lip 94. The notches 98 and 100 facilitate lubricant flow to the annular areas 102 and 104 for added sealing against foreign material entering from the outside. A notch may also be located in outer lip 96 substantially in line with the notch in the inner lip. If desired, non-contacting lips may be used in conjunction with contacting lips to form still another version of our labyrinth seal.

Of course, if desired, holes similar to the holes 33 or 34 in FIG. 2 may be substituted for the notches shown in FIG. 3, FIG. 4, and FIG. 5.

While each seal is illustrated as having all lips integral with the annular body and with each other, the various seal sections could be formed separately and joined together after forming. This joining could be done by bonding together or by mechanically holding together in a seal case or otherwise.

Although not illustrated, each seal with notches or holes may incorporate on the sealing lips any of the well-known hydrodynamic sealing surfaces to assist in the exclusion of outside contaminants and the retention of the internal lubricant.