CA1128570A - End face seal assembly - Google Patents
End face seal assemblyInfo
- Publication number
- CA1128570A CA1128570A CA364,819A CA364819A CA1128570A CA 1128570 A CA1128570 A CA 1128570A CA 364819 A CA364819 A CA 364819A CA 1128570 A CA1128570 A CA 1128570A
- Authority
- CA
- Canada
- Prior art keywords
- face
- seal assembly
- seal
- load ring
- ring
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Abstract
End Face Seal Assembly Abstract of the Disclosure An end face seal assembly has a seal ring, a support ring, and a resilient load ring having individual preselected properties. The load ring and the support ring have improved cross-sectional configurations and have a precise geometrical relationship to each other and to the joint in which they are received.
Description
Description End ~ace Seal Assembly :, .
Technical Field This in~ention ~elates generally to ~n end - ~ -face seal assembl~ and, more particularly, to an end face seal assembly including a load ring having improved stability and a support ring having an impro~ed cross sectional configuration.
Background Art End face seals are commonly used in severe service environments to exclude external contaminants such as grit, water and the like from joints between relatively movable members. One such application for ~
seals of this type is in the pin joints in endless track ~;
chains on track-type earthmoving vehicles. Such track chains operate in extremely abrasive environments under all types o~ weather conditions. Consequently, the axial face load of the seals must be maintained at a substantial level, ~or example, above 100 pounds, to insure that the seal will effectively exclude contami-nants and retain lubricant, even under conditions of minimum load. In addition, the seal must accommodate a considexable amount of axial motion between the track joint members due to cumulative tolerances in manu-~actuXing, stresses and strains in use, and wear. Thisimposes substantial demands upon track pin seals, since the seal must not only be sufficiently resilient to ~ollow rapid moVements of the joint members over a con-siderable temperatuxe xange, but also must exhibit a substantial wear life.
Extensive development work has been directed toward improVing track pin seaLs. Numerous designs have ~ ' r ~ r~ ~
been proposed, but, ~or the most part r they have heen pro~en successful in use onl~ to a limited extent.
In the track chain assembly process pairs of adiacent coacting pivotall~ in~exconnected links are sequentlally pressed onto the ends o~ assQciated pins and bushings until a chain of a preselected length is ~ormed. Typicall~, the links are ~laced upon roller conyeyors, and the seal assemblies are pressed into associated counterbores. Press ~ittin~ of the seal assembly in the link counterbore moves the opposite edges of the inner and outer peripheral suraces of the load ring closer together because of the parallelogram effect. It has been discovered that after assembly, the axial distance between these edges is small enough 15 to render the load ring unstable, that ~s to say, if the -seal assembly is inadvertently bumped on one side, or example by an adjacent link on the conveyor, the axial distance between the opposite edges on the other side may decrease to zero or less. The load ring on that side 20 therefore rotates inwardly and "pops out" of the counter- -bore. If not noticed and the links are pressed on their respective bushing with the seal not properly positioned, premature failure of the joint occurs.
Still another problem associated with prior art seals ~f this type results from the relatively high press or interference ~it, about 0.5% to 2.0% of the diameter, and the operational relationship between the load ~ing and the relativel~ stiff support ring. The magnitude o~ this ~it renders assembly o~ the seal relatively difficult and leads to incon$istent posi-tioning of the seals in the links in the assembly p~o;cess.
Furthe~, when the load riny is in the compressed state, its exterior ~ace bul~es outwardly against the upper incl~ned inner ~urface o~ the support ring creatin~ an undesirable localized area o~ hlgh strain, in the order :.
of approximately 70% in the bulge portion, as opposed to approximately a uniform 6Q% strain in the remaining portion of the load ring. This strain discontinuity reduces the fatigue life of the elastomeric material.
Yet another problem arises at the interface between the load ring and the inclined inner surface of the support ring, where the contact forces are relatively high but gradually taper to zero at the point of last contact between the bulge and the incline. This condition lO permits grit and other contaminants to collect between the ;
two members, and, in operation, the approximately ~ 1 of "windup" or relative rotational motion between the load ring and the support ring causes substantial erosion of the elastomeric material. Significant erosion of the load ring also occurs on start up and stop of the track where "windup" has been found to be as high as + 4. This erosion also contributes to prema-ture track pin joint failure and expensive vehicle downtime.
The foregoing illustrates limitations of the known prior art. In view of the above, it would be advantageous to provide an alternative to the prior art in the form of an improved end face seal assembly having a long life expectancy and operational effectiveness over a wide range of deflection in the severe service environment of a track joint, and which seal assembly will overcome the problems associated with the prior art. `
Disclosure of the Invention In one aspect o~ the present invention, there is provided an end face seal assembly having a resilient load ring and a seal and support ring means concentrically disposed about a central axis, the load ring being positionable between a first seat provided within a first member and a second seat defined about the seal and support means for axially urging the seal and support ring ~' -, ' ~- 4 -means into sealing engagement against an end face of a second member, the resilient load ring being defined by a plurality of preselected surfaces including a cylindrical outer peripheral surface and a first end face extending radially inwardly therefrom for joint engagement with t~e first seat,a cylindrical inner peripheral surface and a second end face e~tending radially outwardly therefrom for `
joint engagement with the second seat, an interior surface connected between the first end face and the inner surface, and an exterior surface connected between the outer surface and the second end face, the improvement comprising; the exterior surface having a shallow arcuate recess in cross-section defined by a radially extending outer portion connected to the outer surface and a revolved radius extending from the outer portion of the second end face, the radially extending outer portion being normal to the central axis.
Brief Description of the Drawings In the drawings:
Figure 1 is a vertical elevational view in cross section of a track joint embodying an end face seal assembly;
Figure 2 is an enlarged view of the end face seal assembly and associated members of Fig. 1 to better illustrate the details thereof; and Figure 3 is an enlarged view of the seal assembly and associated members of Fig. 1 illustrating the seal ;;
assembly in the unloaded position or free state.
Best Mode For Carrying Out the Invention Referring to Fig. 1, a track joint embodying an end face seal assembly 10 is shown generally by the numeral 12. The track joint includes first and second cooperating, pivotally interconnected overlapping links ''. ',' ~ . : ' : ; ', ., . , ., :: :
': `~. ': ': ': ~ :: ' "' ' ' . '' ::
': ':
.;: : ~ . '. , ;. . ' : :
, ' : . : :: ' , . :
. , ':, ~ ' , ,. : : :
- 4a -14,16 coaxially mounted along a pivot axis 18 to a track pin 20 and an associated cylindrical bushing 22 respectively and a spacer ring 24 disposed intermediate the links. ~:, As shown in greater detail ln Fig. 2~ a counter-bore or seat 26 is formed in the first line 14 and is defined by an axially outwardly facing end face 28, a cylindrical surface 3~, and a blended arcuate corner .
'~
`:
~.
;
~:
;' portion 32. The spacer ring 24 is loosely positioned on the t~ack pin 20 and abuts the ~ace 28 and an axiall~ ;
inwardly facing end face 34 on the bushing 22 to limit the minimum axial distance therebetween.
The end face seal assembly 10 is disposed generally concentrically with the axis 18 ~ithin the counterbore 26 and axially seals against the end ~ace 34 of the bushing 22 to retain lubricant within the track joint 12 and to prevent the entry o~ dirt or other contaminants therein. The seal assembly includes a resilient seal r~ng 36 for dynamic primary sealing engagement with the end face 34. The seal rin~ has a generally triangular cross section having a sealing lip ;
or axial outward ace 38 engaging the bushing end face and an annular base 40 which may be securely bonded or otherwise connected to a relatively rigid support ring 42. The seal assembly further includes a resilient load ring 44 for supporting the support ring and the seal ring in the counterbore and for providing static secon-dary sealing engagement with both the support ring andthe counterbore.
Referring now to Figs. 2 and 3, the support ring 42 and the load ring 44 are illustrated in greater detail. The support ring has a generally L-shaped cross sectional canfiguration having a generally axially ex-tending cylindrical portion 46 and an integrally con-nected generally radially extending portion 48. The cylindrical portion defines a cylindrical surface 50 and an axially inner end 52, and the radially extending portion deines an axially in~ardly facing end face 54, an axially outwardly facin~ end face or seat 56, and a rounded, radially outer peripheral edge 58 extending therebetween defining a generally rounded end portion 60.
The base 40 of the seal ring 36 is bonded or otherwise sealingly secured to the outwardly ~acing seat o~ the . . ~, , . , . ~ , . .................. . . , , , , :
,: ; ,~ . , :; ............ . , .. . , . - , , . .......... . .
, . . .:: . , . . : , . - :: ;: . : :
.;. .,, :. , : . :, . ; . :; ~, : :
~%~
--6~-sUppoxt ring. Moreover, a blended arcu~te corner poXtion 62 connects the surface 50 and the end ~ace 54 to define a seat 64 that ~aces opposite the counte~bore or seat 26 in the link 14.
The construction of the load ring 44 is best illustrated in Fi~. 3 where it is sho~n in the unloaded or free state. The load ring i5 preferabl~ constructed of an elastomeric resilient material, for e,xample epichlorohydrin copolymer rubber having a durometer -~
"A" scale hardness magnitude in a range of about 40 to 70 and a relatively low tensile modulus magnitude (Young's modulus) of approximately 3 MPa (5nO psi).
The free cross section thereof is of a generally paral-lelogram shaped configuration defined by cooperating substantially cylindrical, axially extending, outer and inner peripheral surfaces 66,68, A first encl ~ace 70 extendiny radially inwardly from the outer peripheral surface, a second end face 72 extending radially out-wardly rom the inner peripheral surace, a generally concave interior surace 74 extending between the first end face at a first edge 76 and the inner peripheral surace at a second edge 78, and a generally concave exterior surface 80 extending between the outer peri- ' pheral surface at a third ed~e 82 and the second end face at a fourth edge 84.
The outer pexipheral surface 66 of the load ring 44 is in a press ~it relationship with the cylin-drical surface 30 of the counterbore 26. Similarly, the inner peripheral Sur~ace 68 is in a press fit rela-tionship with the cylindrical surface 50 of the supportring 42. The load xing is solely connected to the countexbore and support Xing by these pressed or inter-ference fits without the use of a binding agent.
Prefexably, both'fits lie within a range of a free fit to about 0.4% of the diameters o~ the cylindrical surfaces 30 and 50 respecti~ely.
A pre~erred construct~on parameter of the load ring 44 exists in the pxeselectecL geo~etry o~ the interior sux~ace 74 when it is in the unloaded ox free state. The interior sur-~ace is characterized b~ a shallow arcuate rece$s de~ined by a revol~ed radius R
having a length within a ran~e of about 0.9 to about 1.5 times the distance between the irst and the second edges 76,78. It has been determined that by keeping the radius length within this preselected range, buckling of the load ring will be avoided, if, for example, the radius is too small. Con~ersely, i~ the radius is too large, the axial face load upon the seal ring will increase undesirably fast, because the compressed load riny will ~ill the available space in the counterbore 26 too rapidly.
Another pre~erred construction parameter o~
the load ring 44 resides in the preselected geometry of the exterior surface 80 when it is in the unloaded or free state. The exterior sur-face is characterized by a shallow arcuate recess defined in combination by a radial outer portion 86 normal to the axis 18 and by a revolved radius RR, as indicated on the drawing, having a len~th within a range of about 0.45 to ahout 1.2 times the distance between the third and the ourth edges 82,84. Pre~erably the radius has a length within a ran~e o about 0.5 to about 0.7 times the distance between the third and ourth ed~es, and ideall~, the radius has a len~th appxoximately equal to about 0.6 ti~es the distance between the thi~d and the ~ourth edges.
Yet another preferred construction parameter of the load ring 44 exists in the preselected axial distance C between the second and third edges 78,82 in the free state. W~thin the restrictive limitations , , ,., ., . . ~ ,, , . .. .. . ~ ~
- ,:: , ::, . :. . . .
: .... . ~ . : ..... . :: ~,.: . : .. :
~ . . ,: , . ,,. ,, ~ ,,, .; : , . . -S~7~
imposed by the radial and axial dimension~ of the counterbore xeceiving the seal assembl~, it is a,dvan-ta~eous to maintain this distance within a pxeselected range to contxol the stability of the load xin~. Pxe~ex-~bly, the axial dista~ce C between the second and thirdedges is within the range of about 0.25 to about 0.6 times the o~erall axial length L of the load ring.
Ideally, this distance is ~ithin a range of about 0.3 to about 0.35 times the overall axial length of the load ring.
Industrial Applicability ~ ith the parts assembled as set forth above, the end face seal assembly 10 of the present invention has application wherever it is desirable to provide a seal between two members having relative xotational and limited axial movement therebetween. One such application is in a track pin joint 12 in an endless track chain on track-type earthmoving vehicles.
In operation, the end face seal assembly 10 provides a gradually increasing axial face load on the sealing lip 38 as the load ring 44 is loaded in shear between the seats 26 and 64 and compressed between the free state illustrated in Fig. 3 and the fully loaded state illustrated in Fig. 2 in response to rela-tive axial moVement between the first and second links14,16. The axial ace load is maintained at a pre-s,elected minimum ~alue upon the initial installation of the seal assembl~ in the trac]c joint in ordex to assure positiVe retention of lubricant and to exclude the entry of forei~n contaminants thexein. ~mpo~tantly, the decreased intexference or pressed fit xelationship o~ the load riny and the cylindrical surface 30 of the counterbore 26 results in increased ease of installation o~ the seal and better consistency in assembly thexeof.
. . .~: .,:. .
.
As the seal assembly 10 is compressed, the exterior surface 80 o~ the load ring 44 ls deformed ~.
in such. a way that its concaye shape becomes genexally cur~ilinear, as is best illustrated in ~ . 2. ~:t is 5 of signi~icance to note that in the compressed state~ :`
the impro~ed load rin~ is ~ree ~rom the undesixa~le axially outwardly bulging o~ the exterior ~u~face o~
prior art load rings and the resultant strain discon-tinuity between the bulgin~ portion and the remaining portion thereof. Moreo~er, the exterior load ring surface and the generally rounded end portion 60 o~ the ~
support ring are constructed and arranged so as to be :
free from engagement with one another when the seal assembly is compressed. Advantageously, the absence o~
cont~ct between these seal assembly members 80,60 eliminates the accumulation of dirt and other Eoreign contaminants therebetween eliminating exosion of the elastomeric material of the load ring and associated premature failure of the seal assembly.
Simultaneously, as the load ring 44 is com-pressed the interior surface 74 engages the end face 28 of the link 14 and also allows a controlled increase of the internal strain rate of the load ring. Specifi-cally, the unfilled area 88 between the link end face and the load ring is at least 90% filled by the load ring in the position of maximum compression which maxi- :
mizes effective use of the minimal available space and a~oids weakening of the first link 14 as would be the case with a counter~ore of larger dimensions.
While the present inVention has been described with reference to a prefexred embod.iment, it will be understood by th.~se skilled in the art that various Ghanges may be made and equivalents may be substituted for elements thereof w;thout depaxting from the scope of the invention. In addition, many modi~ications ~nay .
7D~ 5~
, ~
-10~
be made to adapt a particular situation or material to the teachings of the inVention ~ithout departin~ f~om the scope thexeo~. Therefoxe, it is intended that the invention not be limited to the partic:ular embodiments disclosed, but that the inVention wil]. include ~11 embodiments f~lling within the scope o~ the appended claims.
. , ; . ~
., ................... . , . . . , .. ~.
.~, " . : .,:
Technical Field This in~ention ~elates generally to ~n end - ~ -face seal assembl~ and, more particularly, to an end face seal assembly including a load ring having improved stability and a support ring having an impro~ed cross sectional configuration.
Background Art End face seals are commonly used in severe service environments to exclude external contaminants such as grit, water and the like from joints between relatively movable members. One such application for ~
seals of this type is in the pin joints in endless track ~;
chains on track-type earthmoving vehicles. Such track chains operate in extremely abrasive environments under all types o~ weather conditions. Consequently, the axial face load of the seals must be maintained at a substantial level, ~or example, above 100 pounds, to insure that the seal will effectively exclude contami-nants and retain lubricant, even under conditions of minimum load. In addition, the seal must accommodate a considexable amount of axial motion between the track joint members due to cumulative tolerances in manu-~actuXing, stresses and strains in use, and wear. Thisimposes substantial demands upon track pin seals, since the seal must not only be sufficiently resilient to ~ollow rapid moVements of the joint members over a con-siderable temperatuxe xange, but also must exhibit a substantial wear life.
Extensive development work has been directed toward improVing track pin seaLs. Numerous designs have ~ ' r ~ r~ ~
been proposed, but, ~or the most part r they have heen pro~en successful in use onl~ to a limited extent.
In the track chain assembly process pairs of adiacent coacting pivotall~ in~exconnected links are sequentlally pressed onto the ends o~ assQciated pins and bushings until a chain of a preselected length is ~ormed. Typicall~, the links are ~laced upon roller conyeyors, and the seal assemblies are pressed into associated counterbores. Press ~ittin~ of the seal assembly in the link counterbore moves the opposite edges of the inner and outer peripheral suraces of the load ring closer together because of the parallelogram effect. It has been discovered that after assembly, the axial distance between these edges is small enough 15 to render the load ring unstable, that ~s to say, if the -seal assembly is inadvertently bumped on one side, or example by an adjacent link on the conveyor, the axial distance between the opposite edges on the other side may decrease to zero or less. The load ring on that side 20 therefore rotates inwardly and "pops out" of the counter- -bore. If not noticed and the links are pressed on their respective bushing with the seal not properly positioned, premature failure of the joint occurs.
Still another problem associated with prior art seals ~f this type results from the relatively high press or interference ~it, about 0.5% to 2.0% of the diameter, and the operational relationship between the load ~ing and the relativel~ stiff support ring. The magnitude o~ this ~it renders assembly o~ the seal relatively difficult and leads to incon$istent posi-tioning of the seals in the links in the assembly p~o;cess.
Furthe~, when the load riny is in the compressed state, its exterior ~ace bul~es outwardly against the upper incl~ned inner ~urface o~ the support ring creatin~ an undesirable localized area o~ hlgh strain, in the order :.
of approximately 70% in the bulge portion, as opposed to approximately a uniform 6Q% strain in the remaining portion of the load ring. This strain discontinuity reduces the fatigue life of the elastomeric material.
Yet another problem arises at the interface between the load ring and the inclined inner surface of the support ring, where the contact forces are relatively high but gradually taper to zero at the point of last contact between the bulge and the incline. This condition lO permits grit and other contaminants to collect between the ;
two members, and, in operation, the approximately ~ 1 of "windup" or relative rotational motion between the load ring and the support ring causes substantial erosion of the elastomeric material. Significant erosion of the load ring also occurs on start up and stop of the track where "windup" has been found to be as high as + 4. This erosion also contributes to prema-ture track pin joint failure and expensive vehicle downtime.
The foregoing illustrates limitations of the known prior art. In view of the above, it would be advantageous to provide an alternative to the prior art in the form of an improved end face seal assembly having a long life expectancy and operational effectiveness over a wide range of deflection in the severe service environment of a track joint, and which seal assembly will overcome the problems associated with the prior art. `
Disclosure of the Invention In one aspect o~ the present invention, there is provided an end face seal assembly having a resilient load ring and a seal and support ring means concentrically disposed about a central axis, the load ring being positionable between a first seat provided within a first member and a second seat defined about the seal and support means for axially urging the seal and support ring ~' -, ' ~- 4 -means into sealing engagement against an end face of a second member, the resilient load ring being defined by a plurality of preselected surfaces including a cylindrical outer peripheral surface and a first end face extending radially inwardly therefrom for joint engagement with t~e first seat,a cylindrical inner peripheral surface and a second end face e~tending radially outwardly therefrom for `
joint engagement with the second seat, an interior surface connected between the first end face and the inner surface, and an exterior surface connected between the outer surface and the second end face, the improvement comprising; the exterior surface having a shallow arcuate recess in cross-section defined by a radially extending outer portion connected to the outer surface and a revolved radius extending from the outer portion of the second end face, the radially extending outer portion being normal to the central axis.
Brief Description of the Drawings In the drawings:
Figure 1 is a vertical elevational view in cross section of a track joint embodying an end face seal assembly;
Figure 2 is an enlarged view of the end face seal assembly and associated members of Fig. 1 to better illustrate the details thereof; and Figure 3 is an enlarged view of the seal assembly and associated members of Fig. 1 illustrating the seal ;;
assembly in the unloaded position or free state.
Best Mode For Carrying Out the Invention Referring to Fig. 1, a track joint embodying an end face seal assembly 10 is shown generally by the numeral 12. The track joint includes first and second cooperating, pivotally interconnected overlapping links ''. ',' ~ . : ' : ; ', ., . , ., :: :
': `~. ': ': ': ~ :: ' "' ' ' . '' ::
': ':
.;: : ~ . '. , ;. . ' : :
, ' : . : :: ' , . :
. , ':, ~ ' , ,. : : :
- 4a -14,16 coaxially mounted along a pivot axis 18 to a track pin 20 and an associated cylindrical bushing 22 respectively and a spacer ring 24 disposed intermediate the links. ~:, As shown in greater detail ln Fig. 2~ a counter-bore or seat 26 is formed in the first line 14 and is defined by an axially outwardly facing end face 28, a cylindrical surface 3~, and a blended arcuate corner .
'~
`:
~.
;
~:
;' portion 32. The spacer ring 24 is loosely positioned on the t~ack pin 20 and abuts the ~ace 28 and an axiall~ ;
inwardly facing end face 34 on the bushing 22 to limit the minimum axial distance therebetween.
The end face seal assembly 10 is disposed generally concentrically with the axis 18 ~ithin the counterbore 26 and axially seals against the end ~ace 34 of the bushing 22 to retain lubricant within the track joint 12 and to prevent the entry o~ dirt or other contaminants therein. The seal assembly includes a resilient seal r~ng 36 for dynamic primary sealing engagement with the end face 34. The seal rin~ has a generally triangular cross section having a sealing lip ;
or axial outward ace 38 engaging the bushing end face and an annular base 40 which may be securely bonded or otherwise connected to a relatively rigid support ring 42. The seal assembly further includes a resilient load ring 44 for supporting the support ring and the seal ring in the counterbore and for providing static secon-dary sealing engagement with both the support ring andthe counterbore.
Referring now to Figs. 2 and 3, the support ring 42 and the load ring 44 are illustrated in greater detail. The support ring has a generally L-shaped cross sectional canfiguration having a generally axially ex-tending cylindrical portion 46 and an integrally con-nected generally radially extending portion 48. The cylindrical portion defines a cylindrical surface 50 and an axially inner end 52, and the radially extending portion deines an axially in~ardly facing end face 54, an axially outwardly facin~ end face or seat 56, and a rounded, radially outer peripheral edge 58 extending therebetween defining a generally rounded end portion 60.
The base 40 of the seal ring 36 is bonded or otherwise sealingly secured to the outwardly ~acing seat o~ the . . ~, , . , . ~ , . .................. . . , , , , :
,: ; ,~ . , :; ............ . , .. . , . - , , . .......... . .
, . . .:: . , . . : , . - :: ;: . : :
.;. .,, :. , : . :, . ; . :; ~, : :
~%~
--6~-sUppoxt ring. Moreover, a blended arcu~te corner poXtion 62 connects the surface 50 and the end ~ace 54 to define a seat 64 that ~aces opposite the counte~bore or seat 26 in the link 14.
The construction of the load ring 44 is best illustrated in Fi~. 3 where it is sho~n in the unloaded or free state. The load ring i5 preferabl~ constructed of an elastomeric resilient material, for e,xample epichlorohydrin copolymer rubber having a durometer -~
"A" scale hardness magnitude in a range of about 40 to 70 and a relatively low tensile modulus magnitude (Young's modulus) of approximately 3 MPa (5nO psi).
The free cross section thereof is of a generally paral-lelogram shaped configuration defined by cooperating substantially cylindrical, axially extending, outer and inner peripheral surfaces 66,68, A first encl ~ace 70 extendiny radially inwardly from the outer peripheral surface, a second end face 72 extending radially out-wardly rom the inner peripheral surace, a generally concave interior surace 74 extending between the first end face at a first edge 76 and the inner peripheral surace at a second edge 78, and a generally concave exterior surface 80 extending between the outer peri- ' pheral surface at a third ed~e 82 and the second end face at a fourth edge 84.
The outer pexipheral surface 66 of the load ring 44 is in a press ~it relationship with the cylin-drical surface 30 of the counterbore 26. Similarly, the inner peripheral Sur~ace 68 is in a press fit rela-tionship with the cylindrical surface 50 of the supportring 42. The load xing is solely connected to the countexbore and support Xing by these pressed or inter-ference fits without the use of a binding agent.
Prefexably, both'fits lie within a range of a free fit to about 0.4% of the diameters o~ the cylindrical surfaces 30 and 50 respecti~ely.
A pre~erred construct~on parameter of the load ring 44 exists in the pxeselectecL geo~etry o~ the interior sux~ace 74 when it is in the unloaded ox free state. The interior sur-~ace is characterized b~ a shallow arcuate rece$s de~ined by a revol~ed radius R
having a length within a ran~e of about 0.9 to about 1.5 times the distance between the irst and the second edges 76,78. It has been determined that by keeping the radius length within this preselected range, buckling of the load ring will be avoided, if, for example, the radius is too small. Con~ersely, i~ the radius is too large, the axial face load upon the seal ring will increase undesirably fast, because the compressed load riny will ~ill the available space in the counterbore 26 too rapidly.
Another pre~erred construction parameter o~
the load ring 44 resides in the preselected geometry of the exterior surface 80 when it is in the unloaded or free state. The exterior sur-face is characterized by a shallow arcuate recess defined in combination by a radial outer portion 86 normal to the axis 18 and by a revolved radius RR, as indicated on the drawing, having a len~th within a range of about 0.45 to ahout 1.2 times the distance between the third and the ourth edges 82,84. Pre~erably the radius has a length within a ran~e o about 0.5 to about 0.7 times the distance between the third and ourth ed~es, and ideall~, the radius has a len~th appxoximately equal to about 0.6 ti~es the distance between the thi~d and the ~ourth edges.
Yet another preferred construction parameter of the load ring 44 exists in the preselected axial distance C between the second and third edges 78,82 in the free state. W~thin the restrictive limitations , , ,., ., . . ~ ,, , . .. .. . ~ ~
- ,:: , ::, . :. . . .
: .... . ~ . : ..... . :: ~,.: . : .. :
~ . . ,: , . ,,. ,, ~ ,,, .; : , . . -S~7~
imposed by the radial and axial dimension~ of the counterbore xeceiving the seal assembl~, it is a,dvan-ta~eous to maintain this distance within a pxeselected range to contxol the stability of the load xin~. Pxe~ex-~bly, the axial dista~ce C between the second and thirdedges is within the range of about 0.25 to about 0.6 times the o~erall axial length L of the load ring.
Ideally, this distance is ~ithin a range of about 0.3 to about 0.35 times the overall axial length of the load ring.
Industrial Applicability ~ ith the parts assembled as set forth above, the end face seal assembly 10 of the present invention has application wherever it is desirable to provide a seal between two members having relative xotational and limited axial movement therebetween. One such application is in a track pin joint 12 in an endless track chain on track-type earthmoving vehicles.
In operation, the end face seal assembly 10 provides a gradually increasing axial face load on the sealing lip 38 as the load ring 44 is loaded in shear between the seats 26 and 64 and compressed between the free state illustrated in Fig. 3 and the fully loaded state illustrated in Fig. 2 in response to rela-tive axial moVement between the first and second links14,16. The axial ace load is maintained at a pre-s,elected minimum ~alue upon the initial installation of the seal assembl~ in the trac]c joint in ordex to assure positiVe retention of lubricant and to exclude the entry of forei~n contaminants thexein. ~mpo~tantly, the decreased intexference or pressed fit xelationship o~ the load riny and the cylindrical surface 30 of the counterbore 26 results in increased ease of installation o~ the seal and better consistency in assembly thexeof.
. . .~: .,:. .
.
As the seal assembly 10 is compressed, the exterior surface 80 o~ the load ring 44 ls deformed ~.
in such. a way that its concaye shape becomes genexally cur~ilinear, as is best illustrated in ~ . 2. ~:t is 5 of signi~icance to note that in the compressed state~ :`
the impro~ed load rin~ is ~ree ~rom the undesixa~le axially outwardly bulging o~ the exterior ~u~face o~
prior art load rings and the resultant strain discon-tinuity between the bulgin~ portion and the remaining portion thereof. Moreo~er, the exterior load ring surface and the generally rounded end portion 60 o~ the ~
support ring are constructed and arranged so as to be :
free from engagement with one another when the seal assembly is compressed. Advantageously, the absence o~
cont~ct between these seal assembly members 80,60 eliminates the accumulation of dirt and other Eoreign contaminants therebetween eliminating exosion of the elastomeric material of the load ring and associated premature failure of the seal assembly.
Simultaneously, as the load ring 44 is com-pressed the interior surface 74 engages the end face 28 of the link 14 and also allows a controlled increase of the internal strain rate of the load ring. Specifi-cally, the unfilled area 88 between the link end face and the load ring is at least 90% filled by the load ring in the position of maximum compression which maxi- :
mizes effective use of the minimal available space and a~oids weakening of the first link 14 as would be the case with a counter~ore of larger dimensions.
While the present inVention has been described with reference to a prefexred embod.iment, it will be understood by th.~se skilled in the art that various Ghanges may be made and equivalents may be substituted for elements thereof w;thout depaxting from the scope of the invention. In addition, many modi~ications ~nay .
7D~ 5~
, ~
-10~
be made to adapt a particular situation or material to the teachings of the inVention ~ithout departin~ f~om the scope thexeo~. Therefoxe, it is intended that the invention not be limited to the partic:ular embodiments disclosed, but that the inVention wil]. include ~11 embodiments f~lling within the scope o~ the appended claims.
. , ; . ~
., ................... . , . . . , .. ~.
.~, " . : .,:
Claims (5)
1. In an end face seal assembly having a resilient load ring and a seal and support ring means concentrically disposed about a central axis, the load ring being positionable between a first seat provided within a first member and a second seat defined about the seal and support means for axially urging the seal and support ring means into sealing engagement against an end face of a second member, said resilient load ring being defined by a plurality of preselected surfaces including a cylindrical outer peripheral surface and a first end face extending radially inwardly therefrom for joint engagement with said first seat a cylindrical inner peripheral surface and a second end face extending radially outwardly therefrom for joint engagement with said second seat, an interior surface connected between the first end face and the inner surface, and an exterior surface connected between the outer surface and the second end face, the improvement comprising:
said exterior surface having a shallow arcuate recess in cross-section defined by a radially extending outer portion connected to said outer surface and a revolved radius extending from said outer portion to said second end face, said radially extending outer portion being normal to said central axis.
said exterior surface having a shallow arcuate recess in cross-section defined by a radially extending outer portion connected to said outer surface and a revolved radius extending from said outer portion to said second end face, said radially extending outer portion being normal to said central axis.
2. The end face seal assembly of claim 1 wherein said exterior surface extends between an edge on the outer surface and another edge on the second end face and wherein the revolved radius has a length within a range of about 0.45 to about 1.2 times the distance between said edges.
3. The end face seal assembly of claim 1 wherein said load ring in the free state has an overall axial length between said end faces and said exterior surface extends from said outer cylindrical surface at an edge and said interior surface extends from said inner cylindrical surface at another edge, said edges being disposed intermediate said end faces and axially spaced apart from each other a preselected axial distance, said axial distance being within a range of about 0.25 to about 0.6 times the overall axial length.
4. The end face seal assembly of claim 3 wherein said axial distance is within a range of about 0.3 to about 0.35 times the overall axial length.
5. The end face seal assembly of claim 1 wherein said seal and support ring means includes a generally radially extending portion having a generally rounded end portion provided thereon and wherein said load ring is so constructed and arranged that in response to axial loading, said exterior surface deflects in a manner so as to be free from contact with said rounded end portion.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/001,036 US4189178A (en) | 1976-01-29 | 1979-01-04 | Tarpaulin cover system |
| US79/01036 | 1979-12-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1128570A true CA1128570A (en) | 1982-07-27 |
Family
ID=21694074
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA364,819A Expired CA1128570A (en) | 1979-01-04 | 1980-11-17 | End face seal assembly |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1128570A (en) |
-
1980
- 1980-11-17 CA CA364,819A patent/CA1128570A/en not_active Expired
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| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |