Description

Stabilized Seal Structure

Technical Field

This invention relates to seals, and in par- ticular to seals for use in environments where end play may occur.

Background Art

One environment in which seals are utilized wherein end play may occur is that of the track of a track-type material handling vehicle. It is desirable to seal the space between the track pin and associated elements. One example of an improved track pin seal for such purposes is shown in U. S. Letters Patent 3,614 ,113 of Duane L. Burk, which patent is owned by the assignee hereof. In that patent, an improved spring washer structure is provided for urging an annular boot into sealing engagement with confronting track link structures. As pointed out in the Burk patent, extensive efforts have been made to provide suitable seals for such environments. However, the prior art seals have not proven completely satisfac¬ tory.

Disclosure of Invention

The present invention comprehends an improved stabilized seal structure for use in such environments providing improved ability to accommodate end play.

More specifically, the invention comprehends such an improved stabilized seal structure wherein the sealing portion of the seal ring is maintained effec- tively fixed relative to the axially movable member over a substantial range of compression of the seal resulting from such axial movement of the environ-

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mental members.

The improved stabilized seal structure of the present invention permits a preselected amount of end play without decreasing the effective seal space volume.

More specifically, the invention comprehends providing such a stabilized seal structure wherein the seal ring is permitted to expand into a recess in one of the wall members defining the seal space during an initial loading of the seal by the axial movement of the environmental wall member.

In the illustrated embodiment, one of the walls defining the seal space is provided with a recess. Dur¬ ing compression of the seal, a portion thereof may move into the recess so as to effectively maintain the seal space volume during the initial compression thereof.

Resultingly, the contact of the seal with the movable wall is effectively fixed so as to stabilize the seal and provide long troublefree life thereof. In the illustrated embodiment, the seal ring has a C-shaped cross section with a load ring being disposed in a load ring space defined thereby. Com¬ pression of the seal ring urges the load ring against one of the wall members so as to provide a suitable compression-resisting force in effecting the desired seal between the seal ring and the associated environ¬ mental wall members.

The seal defines a bight portion of its C- shaped cross section which is disposed so as to be movable into the recess during the initial compression of the seal. One of the legs of the seal sealingly engages the movable wall member and is effectively maintained in fixed relationship thereto during the initial compression as a result of the movement of the bight portion into the recess during such movement.

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Upon completion of the initial phase of the seal compression, the seal is then allowed to be com¬ pressed in the normal manner so as to provide the de¬ sired final sealing engagement between the seal and the confronting wall members.

The stabilized seal structure of the present invention is extremely simple and economical of con¬ struction while yet providing the highly desirable features discussed above.

0 Brief Description of the Drawing

FIGURE 1 is a fragmentary diametric section of a track chain link provided with a seal such as util¬ ized in the prior art;

FIGURE 2a is a fragmentary enlarged diametric r section illustrating an improved stabilized seal struc¬ ture embodying the invention, the seal structure being shown in a partially installed arrangement;

FIGURE 2b is a fragmentary diametric section similar to that of Figure 2a but illustrating the seal _Q in a final sealed arrangement;

FIGURE 3a is a fragmentary diametric section illustrating a modified form of stabilized seal struc¬ ture embodying the invention;

FIGURE 3b is a fragmentary diametric section 5 similar to that of Figure 3a but illustrating the seal structure in the final sealed arrangement;

FIGURE 4a is a fragmentary diametric section illustrating a further modified form of stabilized seal structure embodying the invention; and 0 FIGURE 4b is a fragmentary diametric section generally similar to that of Figure 4a but illustrat¬ ing the seal structure thereof _^ in the final sealed arrangement.

Best Mode for Carrying Out the Invention

As shown in Figure 1, a seal structure gener¬ ally designated 10 may be utilized for sealing appa¬ ratus, such as track pin apparatus generally designated 11, such as for use in track-type tractors or similar earthworking vehicles. Such environmental structure presents a problem in the sealing thereof because of end play such as may occur between an end member, such as end member 12, and the bushing 13 receiving the track pin 14. As shown in Figure 1, the bushing 13 may be fixed in a link 15 of the track chain 11 and a sleeve 16 may be provided between the outer end of the bushing 13 and the confronting inner surface of the outer member 12. More specifically, as shown in Figure 1, mem¬ ber 12 may define a first wall portion 17 spaced out¬ wardly from a second wall portion 18 defined by the outer end of the bushing 13. The outer member 12 may further define a third wall portion 19 spaced radially. outwardly from the sleeve 16 which effectively defines a fourth wall portion. Thus, as shown in Figure 1, wall portions 17, 18, 19 and 16 cooperatively define a seal space generally designated 20 in which the seal structure 10 is disposed for effectively sealing the annular space 21 between the track pin 14 and bushing 13 against ingress of foreign matter, etc.

As indicated above, end play between the mem¬ ber 12, which may comprise one of the links of the track chain 11, and the bushing 13 may occur in the normal use of the track chain. Seal structure 10 therefore must accommodate the joint end play. To accommodate such end play, initial compression of the seal is con¬ ventionally provided and a substantial compressibility of the seal is similarly provided. These factors have resulted in prior art structures, such as shown in

Figure 1, in instability of the seal wherein the por¬ tion of the seal engaging the movable wall, such as wall 18, is caused to move along the surface thereof, thereby reducing the effective sealing engagement therebetween.

The prior art seal structure 10 may comprise an improved seal arrangement utilizing a C-section seal ring 22 and a load ring 23. Such sealing struc¬ tures are generally well known in the art and are con- ventionally called cartridge-type face seals.

Referring now more specifically to Figures 2a and 2b, an improved stabilized seal structure gener¬ ally designated 24 is shown to define a seal member 25 having a C-shaped cross section defined by a first leg 26, an opposite second leg 27, and a bight portion 28. Leg 26 is juxtaposed to wall 17, leg 27 is juxtaposed to wall 18, and bight portion 28 is ^• juxtaposed to the . fourth wall 16 which may comprise the thrust ring of the track assembly. Legs 26 and 27 cooperate with bight 28 in de¬ fining a load member space 29 in which is received a load member 30. In the illustrated embodiment, each of the walls 17, 18, 19 and 16 comprises an annular wall, the load member space 20 comprises an annular space, the seal member 25 comprises a seal ring, and the load member 30 comprises a load ring. Thus, the wall member 17 is at the outer axial end of seal ring space 20, wall 18 is. at the axial inner end of the seal ring space, wall 19 defines the radially outer boundary of the seal ring space 20, and thrust ring 16 defines the radially inner boundary of the seal ring space.

The invention comprehends the provision in one of the bight 28 of the seal ring 25 or the wall 16 of the environmental structure 11 of a recess facing the other element. Thus, as shown in Figure 2a, a recess

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31 may be provided in the wall 16 opening radially outwardly toward the seal ring bight portion 28. The wall 16 further defines an annular lip 32 at the axial inner end of the recess 31. As shown in Figure 2a, the lip 32 may be aligned with the leg 27 of seal ring 25. In the uncompressed condition of Figure 2a, the seal ring rests on the lip 32 so as to effectively dispose the bight portion 28 of the seal ring radially outward¬ ly of the recess 31. In the illustrated embodiment, the bottom surface 33 of the recess is right circular¬ ly cylindrical and the undistorted radially inner sur¬ face 34 of the seal ring bight portion 28 is similarly right circularly cylindrical.

Leg 27 of the seal ring defines a sealing tip portion 34 which engages the wall 18, as shown in Fig¬ ure 2a, at a portion 35.

Referring now to Figure 2b, when the width of seal ring space 20 is reduced as by more closely jux¬ taposing walls 17 and 18, deflection of the leg 27 causes compression of the seal ring suitably to urge bight 28 into recess 31, thereby causing the effective volume of the seal space 20 to remain substantially constant and cause the engagement of the seal ring surface 34 with the sealing wall surface 35 to remain substantially fixed, thereby effectively stabilizing the sealing action. As shown in Figure 2b, in such disposition, load ring 30 effectively urges the con¬ fronting portions of the seal ring into sealing en¬ gagement with the associated walls of the structure 11 to provide the desired effective seal. Resultingly, notwithstanding end play causing variable spacing be¬ tween walls 17 and 18, the sealing engagement between sealing portions 34 and 35 of the illustrated structure is effectively maintained, thereby providing an i - proved stabilized seal structure.

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As shown in Figures 2a and 2b, the seal member may include an annular projection 36 extending toward the thrust ring 16 adjacent wall 17 and cooperating with lip 32 in defining the recess 31. Referring now to Figures 3a and 3b, a modi¬ fied form of stabilized seal structure generally desig¬ nated 124 is shown to comprise a seal structure gen¬ erally similar to that ^* of seal structure 24 but wherein the radially inwardly extending projection is omitted on the seal ring 125 and the wall 18 defines a rad¬ ially outwardly opening recess 131 defined at its axially outer end by an annular lip 137, in addition to the annular lip 132 at the axially inner end there¬ of. Thus, as shown in Figure 3b, the bight portion 128 of the seal ring 125 is urged downwardly into the recess 131 between the two lips 137 and 132 as a re¬ sult of a decrease in the spacing between walls 18 and 19 in the use of the apparatus.

Thus, stabilized seal structure 124 functions generally similar to 'seal structure 24 in effectively maintaining the volume of the seal space 120 during initial compression of the seal ring by utilizing the recess 131 to accommodate a portion of the seal ring during such movement. Thus, the sealing portion 134 of seal ring 125 is effectively maintained fixed rela¬ tive to the sealing portion 135 of the wall 19.

As shown in Figure 3b, movement of the walls 18 and 19 toward each other is limited by the axial extent of the thrust ring 116. Referring now more specifically to the embodi¬ ment of Figures 4a and 4b, a further modified form of stabilized seal structure generally designated 224 is shown to comprise a seal structure generally similar to seal structure 2 ^' but wherein the recess is provided in the seal ring rather than in the wall 16. Thus, as

shown in Figure 4a, the bight portion 228 of the seal ring 225 defines a radially inwardly opening recess generally designated 231 with the radially outer sur¬ face 238 of thrust ring wall 216 being unrecessed. In the illustrated embodiment, wall surface 238 comprises a right circularly cylindrical wall surface.

The seal ring 225 may further define radially inwardly projecting lips 239 and 240 at the opposite ends of the recess 231. Lips 239 and 240 engage the surface 238 so as to space the bight portion 241 over¬ lying the recess 231 radially outwardly from surface 238 in the uncompressed condition of the seal ring illustrated in Figure 4a.

As a result of a decrease in the space between walls 18 and 19, as shown in Figure 4b, bight portion 241 is deflected into engagement with the wall surface 238 so as to maintain effectively fixed the engagement between seal ring portion 234 and wall portion 235. Thus, stabilized seal structure 224 functions simi- larly to stabilized seal structure 24 in providing an effectively maintained constant volume of the seal space during initial compression of the seal ring so as to effect the desired stability of the sealing en¬ gagement of the seal ring with the wall 19. As may be noted in Figure 4b, the thrust ring

216 effectively limits the decrease in spacing between walls 18 and 19 similarly as does thrust ring 116 in the stabilized seal structure 124.

Thus, each of the embodiments of the stabilized seal structures discussed above provides an improved maintained effectively constant seal space volume dur¬ ing initial compression of the seal ring and result- ingly maintains an effectively stabilized, or fixed, sealing engagement between the seal ring and the con- fronting movable wall member notwithstanding deflection

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of the seal ring leg defining the sealing portion. In each of the embodiments, similar elements or struc¬ tures are identified by similar reference numerals but 100 different.

Industrial Applicability

The improved stabilized seal structures of the present invention may be utilized in a wide range of industrial applications wherein end play or similar movement presents a problem relative to maintained stabilized sealing between a face seal and the environ¬ mental structures. In the illustrated embodiment, the improved stabilized seal structures have been shown as used in a tractor vehicle track chain environment, it being understood that the seal structures may be util- ized in a wide range of industrial applications in ad¬ dition thereto.

Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, the disclosure and the appended claims. The forego- ing disclosure of specific embodiments is illustrative of the broad inventive concepts comprehended by the invention.