Description

BOOT-TYPE FACE SEALS FOR JOINT

Technical Field

This invention relates to seals and in particu- lar to boot-type face seals having associated spring means for maintaining sealing engagement thereof

Background Art

In U. S- Letters Patent 3,614,113 of D ane L. Burke, which patent is owned by the assignee hereof, a boot-type seal is shown for use in sealing a track pin assembly. The seal includes Belleville spring means for biasing opposed portions of the boot into sealing engagement with confronting surfaces of the members to be sealed. The legs of the boot engaged by the opposed Belleville springs are resilient and a bight portion of the boot provides a static seal with a radially out¬ er surface of one of the members to be sealed.

In U. S. Letters Patent 3,269,738, Herman Baumler et al show a seal for use in rotary piston motors wherein a disc spring is embedded in an elastic body and removably connected with a glide ring. The disc spring may be radially slotted.

In U. S. Letters Patent 3,370,895 of George A. Cason, Jr. , a seal is shown for use with drilling bits wherein a spring is provided within a rubber sealing ring. The sealing ring, in turn, is bonded to a resil¬ ient holding ring. Other patents of less pertinency, while showing a number of different forms of seals, are those of George E. Dunn U. S. Patent 2,338,169; F. . Koller U. S. Patent 2,481,430; Bernard F. Kupfert et al U. S. Patent 2,814,513; Fred E. Simpson et al U. S. Patent 3,050,346; Harold L. Reins a U. S. Patent 3,218,107, which patent is owned by the assignee

herepf; Seisakusho British Patent 1,425,364; and Jap¬ anese Patent 131,725.

Disclosure of the Invention

The present invention comprehends an improved joint sealing structure wherein the lip of the sealing ring of the annular seal is urged into sealing engage¬ ment with the confronting sealing surface of the joint member by spring means acting through a rigid seal por¬ tion. The rigid portion of the seal is mounted to a flexible portion, in turn mounted in the counterbore of the joint recess receiving the seal to permit the spring means to maintain a dynamic seal between the lip and the joint member sealing surface notwithstand- ing substantial axial movement between the joint mem¬ bers.

The rigid force-transmitting means is bonded to an outer annular resilient member which is fitted into the counterbore of the recess to support the rigid means radially inwardly thereof. The sealing ring may be connected to the rigid force-transmitting means. In one embodiment, the sealing ring and force-trans¬ mitting means are defined by unitary elements-

The spring means may comprise annular Belle- ville spring means arranged to be deflected past its flat position in the range of movement between the joint members so as to provide an effectively minimized force variation in the sealing force applied by the spring means to the sealing lip. The spring means may engage the rigid portion of the seal in an annular radially inwardly and axial- ly outwardly opening recess so as to act generally ax- ially of the sealing lip radially inwardly of the rad¬ ially outer counterbore surface in which the seal struc- ture is received.

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■' e sealing structure of the pr ^* esent :.. ^• .ver-':. on i- extremely simple and conomical of construction while yet providing the highly desirable features cussed above.

Brief Description of the Drawing

FIGURE 1 is a fragmentary section of a joint having a sealing structure embodying the invention;

'FIGURE 2 is a fragmentary enlarged section >"<f the sealing structure; FIGURE 3 is a plan view in partial section of the seal stiffener;

FIGURE 4 is a fragmentary section illustrating a modified form of joint embodying the invention; and

FIGURE 5 is a fragmentary section illustra..ing still another modified form of sealing structure em¬ bodying the invention.-

Beεt Mode for Carrying Cut the. Invention

In the exemplary embodiment of the inv .nriv..-. as shown in Figures 1-3 of. the drawing, a joint 10 :. κ shown to include a first f:ϊ6mber,.--_herein a link II connected to a link 12 by a pin 13. The illustrated joint comprises a track joint, such as for use in a tractor or the like.

The outer end of the pin is press-fitted i:: by the link 11 and an inner portion of the pin s rorα- ' tionally fitted in a second member, herein' a bushing 14 i link 12. Axial movement between the" bushing -_4 a: ^* . Iinκ 11 is limited by a thrust ring 15 hich, as shcv.n in Figure 2, cooperates with the axially outer inwardly facing surface 16 and the radially outer radially inv:ardly facing surface 17 with a counterbore in liuk 11 to define a seal space 18. The invention comprehends the provision of an improved sealing structure IS within seal -..pace 18 for effectively £ ^• „---ling the joint ir.eir-berr 11 and 14 to each

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other notwithstanding a substantial axial movement therebetwee .

More specifically, as best seen in Figure 2, sealing structure 10 includes a seal ring 20 having a lip portion 21 engaging the axially outer sealing sur¬ face 22 of the bushing.

The seal ring is carried by an annular stiffen- er 23 which, as shown in Figure 2, may have a T-section including a radially extending leg portion 24 having a plurality of openings 25 through which the sealing ring 20 is molded. Seal ring 20 may be formed of any suitable highly abrasion-resistant sealable mold mater¬ ial, one example thereof being polyurethane.

The s iffener 23 may further include a trans- versely extending head portion 26 which is bonded to a resilient annular connecting portion 27 in turn bonded to a rigid annular base 28 which may be formed of a ma¬ terial, such as metal. Base 28 is fitted into cylindri¬ cal surface 17 of recess 18 and, in the illustrated em- bodiment, is press fitted thereinto so as to provide a static seal therewith.

Sealing structure 19 further includes annular spring means generally designated 29 which, in the il¬ lustrated embodiment comprises Belleville spring means including a first axially outer spring 30 and a second axially inner spring 31. Inner spring- 31 has a rpring rate sufficiently high to force outer spring 30 past its flat deflected position as the spacing between mem¬ bers 11 and 14 increases, thereby providing a substan- tially constant spring force to the seal lip over the normal working range of the seal. Base portion 28 of the stiffener is provided with a radially inturned flange 32. The radially outer portion 33 of spring 30 bears against the flange 32 to provide a freely mov- able support for the spring means 29. The radially inner portion 34 of spring 30 engages the radially

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iriner portion 35 of spring 31. The radially outer por¬ tion 36 of spring 31 engages the stiffener leg portion 24 axially outwardly of lip 21 of seal ring 20 so as to provide a spring biasing force acting generally axially toward the lip portion through the stiffener and seal ring 20, as shown in Figure 2.

Stiffener portion 23,24,26 may be formed of a rigid material, such as metal or hard synthetic resin, so as to provide a positive transmission of spring force to the sealing ring 20 and provide an improved dynamic seal of lip 21 with the joint member surface 22.

The Belleville spring means permits substantial axial movement between joint members 14 and 11 and, thus, between surfaces 16 and 22 without substantial change in the sealing action of lip 21 against sealing surface 22. Thus, the flexible connecting portion 27 of the stiffener means assures free movement of the sealing ring 20 under the biasing action of spring means 29 over a substantial range of axial displacement of surface 22 relative to surface 16 while effectively maintaining the lip 21 stabilized at the confronting portion of sealing surface 22.

To further effectively stabilize the action of the sealing structure 19, the Belleville spring is arranged to deflect past its flat position within the range of movement of the joint members so that the var¬ iation in spring force is effectively minimized.

Referring to Figure 3, stiffener leg portion 24 may be provided with six openings 25 equiangularly spaced about the axis of the annular stiffener for improved distributed securing of the seal ring thereto. Referring now to the embodiment of Figure 4, a modified form of sealing structure generally designated 119 is shown to comprise a structure generally similar to that of sealing structure 19 but wherein the sealing

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ring and stiffener inner portion define a unitary ele¬ ment 133. The spring means generally designated 129 comprises a pair of Belleville springs 130 and 131 loaded in series. The springs are arranged to accom- modate ^' the axial seal travel over a relatively flat portion of the total series spring rate curve without passing the flat position. The radially outer portion 133 of spring 131 engages the joint member surface 16 and the radially outer portion 136 of the spring 131 engages a radially inner portion 12.4 of the element

137. Element 137 further defines a sealing lip portion 121 sealingly engaging the joint sealing surface 22 and is maintained in dynamic sealing engagement there¬ with by the spring means 129 acting through the ele- ment 137.

A resilient connecting portion 127 is bonded to the element 137 and is compressed within the counter bore surface 17 to provide a static seal therewith. Thus, the sealing structure 119 provides an improved dynamic seal of lip 121 with the joint seal¬ ing surface 22 over a wide range of movement between the joint members 14 and 11 as in the embodiment of Fig ures 1-3 as a result of the maintained sealing force provided by spring means 129 through the stiffener and sealing element 137 to the lip portion 121 thereof with such movement being freely permitted by the flex¬ ible connecting portion 127 of the sealing structure.

In the illustrated embodiment, the element 137 is formed of an abrasion-resistant, relatively hard, high modulus, sealable synthetic resin, such as hard polyurethane. As will be obvious to those skilled in the art, other suitable materials may be utilized for the stiffener and sealing element.

A further modified form of sealing structure generally designated 219 is illustrated in Figure 5.

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Sealing structure 219 is generally similar to sealing structure 19 but utilizes a T-shaped stiffener element 223 having the seal ring 220 bonded thereto so as to dispose the sealing lip 221 in sealing engage- ent with the joint member surface 22. The head portion

226 of the stiffener is bonded to a connecting portion

227 which, in turn, is received in the counterbore 17 of the link 11 so as to have a static seal therewith.

Spring means 229 may be provided in the form of a pair of annular Belleville springs 230 and 231 loaded in series and functioning in the manner previously des¬ cribed relative to spring means 129. The radially outer portion 233 of spring 230 engages the joint member sur¬ face 16 and the radially outer portion 236 of the spring 231 engages the leg portion 224 of the stiffener 223 generally axially outwardly of the sealing lip 221 so as to provide a maintained biasing of the sealing lip against the sealing surface 22 at all times notwith¬ standing a substantial axial movement between the joint member surfaces 22 and 16.

Movement of the sealing lip 221 to follow move¬ ment of the surface 22 is readily permitted by the flex¬ ible connecting portion 227 under the biasing action of the spring- means. The stiffener may be formed of any suitable material, such as metal or relatively hard synthetic resin, so as to provide a positive transmis¬ sion of the biasing force to the sealing lip, as dis¬ cussed above.

Thus, each of the embodiments of the invention as discussed above provides an improved maintained sealing of the seal ring lip with the confronting joint sealing surface over a wide range of axial movement of that surface relative to the opposed joint member. The invention comprehends providing an improved stiffener for transmitting a substantially constant spring bias-

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ing force to the sealing lip and further contemplates providing a connecting portion of the seal which per¬ mits such constant spring force to be applied to the sealing lip over a wide range of movement between the joint members.

Similar elements of each of the different em¬ bodiments are identified by similar reference numerals but 100 different.

Industrial Applicability The sealing structure of the present invention may be utilized in a wide range of different indus¬ trial applications. In the illustrated embodiment, the sealing structure is utilized in a track joint wherein the track links are movably connected by a pin and wherein maintained lubrication is a desideratum. As will be obvious to those skilled in the art, the improved sealing structure is advantageously employed wherever an annular seal is utilized in sealing joint members having substantial relative axial movement therebetween and in an abrasive external environmen - The improved novel sealing structure of the present invention provides a number of highly desira¬ ble features in such track joint applications. More specifically, the provision of the connecting portion of the seal as a separate element permits it to be formed of a material having optimum resilience char¬ acteristics over a wide temperature range as this por¬ tion of the seal does not perform the sealing function. Reversely, as the seal ring portion of the sealing structure is divorced from any requirement for flex¬ ibly supporting the structure, it may be formed of a material having optimum and uncompromised wear and abrasion-resistance so as to define an optimum seal¬ ing element. Still further, as the sealing structure may be

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formed by swaging the base element radially inwardly, the connecting portion of the sealing structure may be placed in radial compression to reduce fatigue in the operation of the sealing structure. The sealing structure may comprise a permanent¬ ly encapsulated assembly which is effectively tamper- proof as it effectively prevents unauthorized disassem¬ bly without destroying the base element configuration. Further, the base element flange provides an improved hard wear bearing portion for the Belleville springs so as to permit controlled supported deflec¬ tion of the springs in the operation of the sealing structure.

The Belleville springs may have different spring rates so as to provide improved loading char¬ acteristics in the sealing structure. Thus, the inner spring engaging the stiffener, or seal, may have a relatively high spring rate with the outer spring having a relatively lower spring rate to permit facili- tated deflection past the flat position thereof in achieving the desired relatively constant load char¬ acteristic of the sealing structure.

As indicated above, the invention comprehends that the springs may be utilized alternatively to move past the flat position or reach the flat position in the maximum travel position thereof in the operation of the sealing structure. In either mode of utiliza¬ tion, the springs provide an improved flat load char¬ acteristic. In the forms of the invention wherein the rigid base member is not utilized, the resilient connection portion may be compressed within the joint bore in direct facial contact with the joint so as to provide an improved modified form of sealing structure as dis- cussed above.

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Other aspects, objects and advantages of this invention can be obtained from a study, of the draw¬ ings, the disclosure and the appended claims. The foregoing disclosure of specific embodiments is il¬ lustrative of the broad inventive concepts comprehende by the invention.

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