Augmented crescent seal with compensating load ring

Claim 2

A seal assembly comprising first and second axially spaced members mounted for relative rotation about a common axis, the first member having a counterbore formed in one face, the second member having an end face opposite the counterbore, a seal ring of tough abrasion resistant material having a crescent shape in cross-section disposed in the counterbore with the crescent shaped cross section defining an annular groove facing the sidewall of the counterbore, the seal ring including a driving flange engaged in non-rotative driving contact with the sidewall and an end wall of the counterbore at the juncture of these walls, a sealing flange engaged in annular face sealing rotative contact with the end face of the second member, the driving said sealing flanges being interconnected by a wall section of substantially thinner cross section than that of the flanges, the thin dimension imparting thereto a substantial lateral flexibility while retaining a torsional modulus characteristic of the tough abrasion resistant material, and a load ring of elastomeric material having substantial spring response characteristics, said load ring being disposed within the annular groove of the crescent shaped seal ring and engaging substantially the entire inner wall surface of the sealing flange and being axially compressed between the driving flange and the sealing flange, the interconnecting thin wall section having a resiliency and torsional modulus such that virtually all driving torque is transmitted from said driving flange to said seal flange therethrough, whereas virtually all of the seal flange face load is derived from compression of said load ring.

Claim 3

The seal assembly of claim 1 wherein the load ring has a polygonal shape in cross-section.

Claim 4

The seal assembly of claim 2 wherein the seal is subjected to dynamic conditions of operation in which the end face of the second member may move axially toward and away from the counterbore through distances sufficiently large to produce rapid and substantial axial compression and expansion of the seal ring and the load ring and wherein the polygonal shape of the load ring is canted to an area of contact including the juncture of the sealing flange and the thin wall section to concentrate thereagainst under axial compression, a radially inwardly directed force to counteract a tendency of the sealing flange toward radial excursions during variations in such compression and thus to maintain the band of sealing contact between the seal ring and second member at substantially the same radial location during such dynamic conditions of operation.

Claim 5

The seal assembly of claim 1 wherein the tough sealing flange extends sufficiently close to the sidewall of the counterbore to prevent the elastomeric load ring from extruding into the space between the outer radial edge of the sealing flange and the sidewall of the counterbore.

Claim 6

The seal assembly of claim 4 wherein the sealing flange includes a surface comprising a face presented to the load ring, the face being inclined at a negative angle in the installed condition of the seal to partially embrace and thus to hold the load ring in position.

Claim 7

The seal assembly of claim 1 wherein the sealing flange includes an outer radial edge, the edge when in the installed condition of the seal forming an angle with the end face in the range of 45* to 120*.

Claim 8

The seal assembly of claim 6 wherein the angle is less than 90*.

Claim 9

The seal assembly of claim 1 wherein the sealing flange is spaced apart from the sidewall of the first member while extending sufficiently close thereto to prevent the load ring from extruding through the space between a radial edge of the sealing flange and the sidewall of the first member.

Claim 10

The seal assembly of claim 8 wherein the sealing flange has an angularly formed Annular edge which remains pressed into intimate engagement with the load ring during operation of the seal assembly to prevent the entry of foreign material therebetween.

Claim 11

A seal assembly in an annular cavity formed by first and second members which are subject to relative rotation, the first member forming the axially facing end wall and a radially facing sidewall of the cavity, the second member having an end face forming another axially facing end wall of the cavity opposite the one axially facing end wall, comprising a seal ring of tough abrasion-resistant material having a crescent shape in cross-section, the seal ring being disposed in the annular cavity with an annular groove of the crescent-shaped seal ring facing the sidewall of the cavity, the seal ring having a driving flange engaged in non-rotative driving contact with the sidewall and the one end wall of the cavity at the junction of these walls and a sealing flange engaged in face sealing rotative contact with the end face of the second member, the seal ring also having a thin-wall section connecting the flanges and providing a flexible hinge therebetween, and a load ring of resilient elastomeric material being disposed adjacent the sidewall of the first member and encompassed by the crescent-shaped cross-section of the seal ring and engaging substantially the entire inner wall surface of the sealing flange whereby the load ring is axially compressed between the driving flange and the sealing flange, axially acting forces for urging the sealing flange against the end wall of the second member and maintaining substantially constant sealing engagement therebetween are provided substantially by compression of the load ring.

Claim 12

A seal assembly in an annular cavity formed by first and second members which are subject to relative rotation, the first member forming the axially facing end wall and a radially facing sidewall of the cavity, the second member having an end face forming another axially facing end wall of the cavity opposite the one axially facing end wall, comprising a seal ring of tough abrasion-resistant material having a crescent shape in cross-section, the seal ring being disposed in the annular cavity with an annular groove of the crescent-shaped seal ring facing the sidewall of the cavity, the seal ring having a driving flange engaged in non-rotative driving contact with the sidewall and the one end wall of the cavity at the junction of these walls and a sealing flange engaged in face sealing rotative contact with the end face of the second member, the seal ring also having a thin-wall section connecting the flanges and providing a flexible hinge therebetween, and a load ring of resilient elastomeric material being disposed adjacent the sidewall of the first member and encompassed by the crescent-shaped cross-section of the seal ring and engaging substantially the entire inner wall surface of the sealing flange whereby the load ring is axially compressed between the driving flange and the sealing flange, axially acting forces for urging the sealing flange against the end wall of the second member and maintaining substantially constant sealing engagement therebetween are provided substantially by compression of the load ring.

Claim 13

The seal assembly of claim 10 wherein a surface on the sealing flange angularly engages the end wall of the second member, the surface on the sealing flange being sufficiently resilient to form a narrow band annular seal surface in contact with the end wall of the second member under axial force provided substantially by the load ring.

Claim 14

The seal assembly of claim 11 wherein the driving flange of the seal ring is sized to provide an interference fit with the sidewall of the first member, the driving flange also being urged into driving engagement with the end wall of the first member, the hinge section of the seal ring being formed with sufficient strength so that driving torque is transmitted between the driving flange and sealing flange substantially by the thin wall hinge section rather than the load ring.

Claim 15

The seal assembly of claim 10 wherein the driving flange of the seal ring is sized to provide an interference fit with the sidewall of the first member, the driving flange also being urged into driving engagement with the end wall of the first member, the hinge section of the seal ring being formed with sufficient strength so that driving torque is transmitted between the driving flange and sealing flange substantially by the thin wall hinge section rather than the load ring.

Claim 16

The seal assembly of claim 10 wherein the sealing flange is spaced apart from the sidewall of the first member while extending sufficiently close thereto to prevent the load ring from extruding through the space between a radial edge of the sealing flange and the sidewall of the first member.

Claim 17

The seal assembly of claim 14 wherein the sealing flange has an angularly formed annular edge which remains pressed into intimate engagement with the load ring during operation of the seal assembly to prevent the entry of foreign material therebetween.

Claim 18

The seal assembly of claim 10 wherein the seal ring has relatively poor spring characteristics particularly at low temperatures because of its selection for abrasion resistance, the load ring being formed from an elastomeric material with good spring characteristics even at low temperatures.

Claim 19

The seal assembly of claim 16 wherein the seal ring is a polyurethane elastomer having a high torsional modulus.

Claim 20

The seal Assembly of claim 10 wherein the seal ring is formed from material selected to have a high torsional modulus and the load ring is formed from an elastomeric material having good spring retraction characteristics even at low temperatures, the thin wall section of the seal ring having suitable resiliency and a torsional modulus such that driving torque is transmitted from the driving flange to the sealing flange substantially by the thin wall section while substantially all of the seal flange face load is derived from compression of the load ring.

Claim 21

A seal assembly for a linkage of the kind in which an outer link and an inner link have overlapping ends joined in a pin joint connection providing for relative rotation about a pin which extends through the ends of both links, the pin being connected to the outer link and rotating within a bushing connected to the inner link, the bushing having an end face facing a counterbore in the inner face of the outer link, the seal assembly comprising an annular seal ring of crescent-shaped cross-section embracing a load ring within the counterbore, the seal ring being a tough, abrasion-resistant material with relatively poor spring characteristics at low temperature and having a drive end pressed into frictional driving engagement with the side wall and end wall of the counterbore, a sealing end having an outer surface a narrow width portion of which comprises a seal band pressed into rotatable sealing contact with the end face of the bushing, and a wall section interconnecting the drive and said seal ends, the wall section being of thin cross-section relative to that of the ends whereby to provide a flexible, hinge-type action, the load ring being an elastomeric compound with good spring retraction characteristics at low temperature and having a polygonal shape in cross section, the load ring being compressed within the annular groove formed between the embracing drive and sealing ends of the crescent-shaped seal ring with a portion of the load ring engaging substantially the entire inner wall surface of the sealing band to produce the major part of the face load for the seal end and wherein the relative configurations and dimensions of the drive end and said counterbore produce an interference fit therebetween effective to transmit the driving torque from the outer link through the seal ring without the need to rely on driving contact through the load ring.

Claim 22

A seal assembly for a linkage of the kind in which an outer link and an inner link have overlapping ends joined in a pin joint connection providing for relative rotation about a pin which extends through the ends of both links, the pin being connected to the outer link and rotating within a bushing connected to the inner link, the bushing having an end face facing a counterbore in the inner face of the outer link, the seal assembly comprising an annular seal ring of crescent-shaped cross-section embracing a load ring within the counterbore, the seal ring being a tough, abrasion-resistant material with relatively poor spring characteristics at low temperature and having a drive end pressed into frictional driving engagement with the side wall and end wall of the counterbore, a sealing end having an outer surface a narrow width portion of which comprises a seal band pressed into rotatable sealing contact with the end face of the bushing, and a wall section interconnecting the drive and said seal ends, the wall section being of thin cross-section relative to that of the ends whereby to provide a flexible, hinge-type action, the load ring being an elastomeric compound with good spring retraction characteristics at low temperature and having a polygonal shape in cross section, the load ring being compressed within the annular groove formed between the embracing drive and sealing ends of the crescent-shaped seal ring with a portion of the load ring engaging substantially the entire inner wall surface of the sealing band to produce the major part of the face load for the seal end and wherein the relative configurations and dimensions of the drive end and said counterbore produce an interference fit therebetween effective to transmit the driving torque from the outer link through the seal ring without the need to rely on driving contact through the load ring.