MXPA99002265A - End face seal with sacrificial wear-in excluder - Google Patents

Abstract

An end face seal especially adapted for use in severe service environments such as for sealing track pins or track rollers of crawler type tractors. The seal includes a primary annular seal ring (12), having a radially extending flange portion (54), as well as a secondary annular sealing ring (14) positioned in use about the axial flange portion. The secondary seal ring includes an abradable auxilliary excluder type lip (90) that contacts a portion of the machine part with the mating surface so as to initially exclude grit from the seal band area of contact between the seal ring and the machine part.

Description

"EXTREME SIDE SEAL WITH SACRIFICE WEAR ELIMINATOR" BACKGROUND OF THE INVENTION The present invention relates generally to mechanical end face seals, and more particularly to seals that are intended to exclude sand or grit from a sealed region and retain oil, grease or other fluid within that region. As the name implies, a mechanical end face seal is a seal where a dynamic seal is formed where the opposite end faces of two relatively rotating elements meet, an element of which is relatively fixed and the another of which moves axially during use to the extent necessary in accordance with an anticipated scale of movement caused by use, dynamic wear or other conditions that characterize the application. In an end face seal, the seal band is basically in a radial plane, while the seal band of an edge seal or arrow forms a cylindrical pattern. The advantages of the invention are achieved in practice by providing a primary seal ring of annular cross section of generally "L" shape in cross section, with a seal band on the front face of its radial leg, and a seal ring secondary having annular secondary seal surfaces are respectively coupled with a machine-enlarged hole and a seal formed by the rear face of the radial leg of the primary ring and the radially external surface of the axial leg of the primary ring with the secondary seal ring including also an abradable auxiliary eliminating edge, preferably in the form of a front annular extension having a leading edge covering the radially outer surface of the radial leg also being above and contacting a part of the second machine element radially towards outside the primary seal band. The manner in which the aforementioned objects and other objects and advantages are achieved in practice will be more clearly evident when reference is made to the following detailed description of the preferred embodiments of this invention which is pointed out by way of example and which is shown in the accompanying drawings, in which like reference numbers indicate corresponding parts.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a detailed perspective view of the seal assembly of the invention showing the primary seal ring element, the load application combination, and the secondary sealing element and a separating unit before the Assembly and installation of the same in the application; Figure 2 is an enlarged vertical sectional view of the seal assembly of Figure 1, shown with the seal pieces in their assembled relationship, but before being placed above the separator and toward the application; Figure 3 is a vertical sectional view of the seal assembly of the invention with broken portions, and showing and sealing in place with a sealed mechanism but before the use of the mechanism; Figure 4 is a view similar to that of Figure 3 and showing the seal after at least a part of the wear or wear action has been carried out during the initial use of the seal; and, Figure 5 is a diagrammatic view showing the configurations of the secondary seal ring and its relaxed and compressed conditions, respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION While it will be understood that the invention can be constructed in different forms and from other different materials, a brief description of the currently preferred seal shape that is intended for use in heavy-duty environments will be provided. Serious service such as use on caterpillar rollers or crawler pins of construction machinery including vehicles for road laying, such as bulldozers, cranes, backhoes and mechanical shovels or as components of other mechanisms that undergo rotary pivot movement, for example. Referring now to the drawings in greater detail, Figures 1 and 2 show a generally designated seal assembly 10 made in accordance with the invention. The two main components of the assembly 10 include a primary seal ring designated generally 12, and a combination of secondary seal and seal ring generally designated 14. Sometimes and in the present and in the claims, the expression "charge ring" is It will be used to describe the element 14, it being understood, as will be explained in more detail herein, that this ring provides a plurality of functions, including the load-applying function during use. With reference to Figures 3 and 4, it will be noted that a sealed mechanism designated generally 16 serves as the environment for the seal assembly 10 and that this mechanism 16 includes an arrow 18 of the crawler pin or crawler roller having a cylindrical outer diameter surface 20 through which the inner diameter surface 22 of an end cap or a similar number 24 is placed in press fit or other fluid-tight relationship. The end cap 24 includes a generally cylindrical widened surface 26, an annular, radially inner or widened end face surface 28 and an annular radially outer end or radial end face end face 30. The sealed mechanism also typically includes a bushing 32 having its outer diameter surface 34 snapped into the cylindrical surface 35 in a support member such as a core 36 or the like, and a generally designated spacer 15 having surfaces 17, 19 cylindrical radially internal and external. The internal cylindrical surface 38 of the hub 32 is separated from the outer diameter surface 20 of the arrow 18 by a working clearance "C" (Figure 4), which accommodates the lubricant and allows relative movement of the parts. If the parts are those such as a crawler pin, the movement is one of oscillation, while if the piece 18 is a supporting arrow of the crawler roller or the like, the relative movement is one of rotation about the axis of the roller pin. . Referring again to Figures 3 and 4, for example, the bushing 32 includes an end face 42 and a chamfered outer corner 44. The various parts just described define a seal receiving cavity which is generally designated 46 (FIG. 3) which is divided by the seal into a pair of connected internal or sealed regions 48a, 48b, and an outer region 50 exposed in contact with the conditions outside of the seal. These conditions may include the presence of water, sand, and grit of various types. Referring now to the construction and installation of seal ring 12 positioned within region 46, and also referring to Figures 1 and 2, ring 12 of the seal is shown as having a generally designated body 51 having a flange 52 axial, a radial flange 54 defined in part by the tapered front surfaces 56, 58 that are joined along a circular site 60 which during use will form a primary seal band when brought into contact with the end face 42 of the 32 bushing and in tight sealed fluid tight coupling. The radial flange 54 also preferably, but not necessarily, include a generally designated auxiliary seal rib 62 that is shown as having a flexible body 64 that includes an end face surface 66 also adapted to contact the end face 42. of the hub 32. As shown, the radial flange 54 also has a circumferentially extending radially outer surface 67. A generally designated seat 69 (Figure 1) for the load ring 14 is formed in part by a radially extending face surface 70, annular in the radial tab 54 and partly by the radially external cylindrical surface 71 in the axial flange 52 of the seal ring. The inner diameter surface 72 of the axial flange 52 is retained in spaced relation to the outer diameter surface 19 of the generally designated spacer 15, preferably by a plurality of axial ribs 73 that dampen the compression load. The spacer 15 holds the bushing 32 and the end cap 24 apart and contacting and holding the ribs 73, the spacer assists in providing rigidity to the flange 52. The ribs 73 transmit the radial face from the ring 14 to the spacer and also they provide axial passages 74 for the lubricant to pass between regions 48a and 48b (Figures 3 and 4). Referring now to the load or the secondary sealing ring and force applicator designated generally 14, this unit is best shown in Figures 1 and 2. Ring 14, which undergoes significant distortion during use, has an elastomeric body designated generally 75 which is shown as including radially and axially extending annular surfaces 76, 78 that during engagement engage the seat 69, where the duplicated surfaces 70, 71 of the seal ring 12 are formed. The ring 14 also includes a surface 80 of external diameter of coupling and enlarged hole and an inclined free rear surface generally designated 82 and shown as including a segment 84 of the inclined surface more substantially and a segment 86 of external surface inclined more gradually , each extending radially outwardly and axially inward towards the sealed region and away from the seal band portion of the primary seal ring. As used herein and in the claims, "axially external" means toward the seal band of the primary seal ring and "axially internal" means away from the seal band 60 and to the left as shown in the drawings. By contrasting Figures 1 and 2 that in Figures 3 and 4, it will be noted that during use, the load ring experiences axial distortion as it is compressed by the assembly process. This axial drawback of the ring under the installation forces causes the ring to expand (or try to expand) radially both inwardly in relation to its internal diameter and outwardly relative to its outer circumference, subjecting itself to the enlarged perforation and creating a radial compression load on seal ring 12. This allows the torque to be transmitted from the end cap to the seal ring 12. This development of the radial load is illustrated in a simple schematic manner in Figure 5 which shows that when there is a considerable flattening or movement towards vertical flattening, a parallelogram-shaped ring or "Belleville spring" tends to move its internal and external diameters. moving away from each other as their cross section becomes flatter and less frustoconical. In the illustration of Figure 5, these surfaces are the four sides A, B, C D of a non-stressed parallelogram with a certain cross-sectional area. When the Belleville spring moves to try to radially align the surface B and D, the elastomeric shape resists trying to expand radially and distorting the surfaces A and C in such a way that the cross section is of greater radial and axial dimension. The resistance to this change in shape generates both an axial end face load and load - lu ¬ radial compression. Even though the shape of the ring 14 is a shape that is not a true parallelogram, its behavior is analogous. Because the elastomeric ring 14 as manufactured (in its non-stressed condition) has an outer diameter slightly smaller than that of the enlarged hole 26, it initially slides freely into the enlarged bore. Therefore, it is desirable that the body 51 include a positioning or positioning spike 88 that extends radially outwardly to the seal band 60. Once the load is applied by axial compression, the ring 14 is tightly retained in the enlarged hole. In addition, of the aforementioned components, the secondary seal and the loading ring 14 of the invention substantially includes a deformable annular eliminator seal body 90 having a deformable internal surface 92 adapted to contact the chamfering 44 of the bushing. , with the seal body 90 having a sacrificial end portion 94 (Figure 4) that will be subjected to abrasion during the period of use. According to the invention, the primary seal ring 12 is made of a durable, relatively rigid but resilient material such as a urethane elastomer having a durometer of about 80.

These hard elastomers are capable of effecting a tight fluid tight seal with the finished and lubricated end face 42 of the hub machine 32 under normal conditions. However, in order for this seal to be achieved in practice, a period of use or accommodation is required. This may require as little as about 10 hours to possibly 50 to 200 hours of operation. With mechanical end face seals using hard metals, such as the seals described in US Pat. No. 3,241,583, a satisfactory but very expensive overlap or process can be carried out on the components before they are assembled. However, with the durable rubber products used in the present invention, the two matching surfaces are manufactured by different suppliers and can not be assembled or accommodated before the final installation. Other reasons also impede this process. Experience with serious service seals of the type with which the present invention relates has established that the grit to which the seals are exposed can easily penetrate the thin flexible first disposable edge that is provided in a customary manner and enter the area. of interface or seal band before the accommodation process is completed. Accordingly, by keeping in accordance with the present invention, there is provided an annular eliminator body which is intended to provide an initial seal on the bevel or tapered surface 44 of the bushing 32 instead of on its end face 42. Because it is made of a relatively softer elastomer that easily deforms through an outer surface of the bushing, including the chamfering of the bushing, the bevel or even the outer end face of the bushing, the secondary ring is more flexible than the bushing. hard rigid elastomer of the primary seal ring and the auxiliary seal 62. Therefore, even though the load ring lacks high abrasion resistance of the hard elastomer, it is much more flexible. Accordingly, it has been shown that the initial lack of confidence caused by premature exposure to grit particles in the area of the seal band can be virtually eliminated. Due to the difficulty and expense of removing seals for replacement purposes, the reliability and extension of occasional "infant mortality" are of crucial importance in many applications, and the present invention provides a seal assembly that is capable of overcoming these difficulties. . Because, as noted, the annular eliminator body 90 is manufactured from a relatively soft elastomer, has a sacrificial character when exposed to significant quantities of grit such as are frequently encountered during the use of the sealed mechanism. Therefore, as shown in Figure 4, the end portion of the eliminator body 90 wears out after a few hundred hours or less, but this is not important for the total reliability of the product because by then. , the primary seal band has established a sand-tight lane on the end face of the bushing and this seal is then reliable for a prolonged period of time, such as several thousand hours of operation. Although the preferred construction currently involves an elastomeric annular eliminator body which is formed in a cylindrical configuration and moves to an inclined position to develop a load of strength while resting on a bevel or chamfer taper formed in the hub, the principles of the invention can be applied to somewhat different forms of the sacrificial eliminating body. However, the beveled arrangement discussed in combination with the deformable body provides a combination of self-centering action and elastomeric load which is highly desirable during use. However, other arrangements can provide a radial load by the elastomeric secondary seal body radially outwardly of the primary seal band. These sacrificial elements can be used with or without one of the auxiliary seal bands in the primary ring.

Claims (12)

R E I V I N D I C A C I O N E S:

1. In a sealed mechanism comprising a first machine part with a radially extending end face sealing surface and a second relatively movable machine part with radial and axial annular seal seating surface portions, a seal assembly heavy duty adapted to retain the lubricant within a sealed region remaining between the portions of the mechanism and the portions of the seal assembly and to extrude the contaminants from the sealed region, the seal assembly comprising, in combination, a primary seal ring and a combination of load application and secondary seal ring associated with the primary seal ring, the primary seal ring has an annular body formed of a rigid, but resilient, abrasion-resistant material that is generally " L "in cross section to include radial and axial flanges, the radial flange includes at least one end face With an axially external bearing with a portion forming a primary seal strip on the sealing surface of the end face of the first machine part, and an axially extending radially extending internal seating surface, the axial flange has a seating surface cylindrically extending axially radially outwardly, and a radially inwardly directed cylindrical surface positioned in relation to one of the machine parts, the secondary sealing ring is made of an elastomer and includes an axially external seating surface which it generally extends radially or in at least partial contact with the axially internal seating surface in the primary seal ring, a cylindrically radially inwardly directed surface seated in the axial flange of the primary seal ring, a sloping surface which is extends radially outward and towards one of the surfaces The seal set of the second machine part and a radially outer cylindrical surface which comes into contact with another of the seal settling surfaces in the second part of the machine, the seal assembly further includes an abrasive scavenger edge , flexible that extends axially outwardly from the body of the secondary seal ring and toward sealing contact as a portion of the first piece of the machine that is radially outwardly of the primary seal band.

2. A seal assembly according to claim 1, wherein the abrasive eliminating edge - In ¬ Flexible is formed integrally with the load-applying combination and the secondary seal ring.

3. A seal assembly according to claim 2, wherein the flexible abrasive scavenging edge and the body of the load-applying combination and second secondary ring are formed in one piece.

4. A seal assembly according to claim 1, wherein the secondary seal and charge applicator combination is made of a synthetic elastomer.

5. A seal assembly according to claim 1, wherein the primary seal ring is made of a resinous, synthetic, durable and tenacious material.

6. A seal assembly according to claim 1, wherein the first piece of the machine includes a bushing having a chamfered corner surface, the eliminating edge is brought into contact with the surface of the chamfered corner of the bushing.

A seal assembly according to claim 1, wherein the radially inwardly directed surface of the axial flange of the primary seal ring includes first portions adapted to engage one of the pieces of the machine and second circumferentially spaced portions that form channels - ?? between the seal ring and one of the parts of the machine, whereby, the primary ring is structurally supported by contact with a piece of the machine and within which the channels provide lubricant passages.

A seal assembly according to claim 1, wherein the radially inwardly directed surface of the axial flange of the primary seal ring is an entry surface.

9. A seal assembly according to claim 1, wherein the primary seal ring is made of a urethane elastomer.

A seal assembly according to claim 1, wherein the end face portion forming the end face seal comprises a pair of frustoconical annular surfaces that meet at a shallow angle to define a band area of primary seal.

A heavy duty seal assembly according to claim 10, wherein the primary seal ring further includes an auxiliary seal body that is radially outwardly of the seal band, the auxiliary seal has a free end portion. which extends in contact with a portion of the sealed mechanism, just radially outwardly of the seal band.

12. A sealed mechanism comprising, in combination, a generally cylindrical arrow unit, an end cap positioned above the arrow unit in tight fluid-tight relation, a cylindrical flared hole and an end face of the flared hole formed in the cap to receive a portion of the seal assembly, a bushing positioned above the arrow and separated therefrom by a radial working clearance to accommodate the lubricant, the bushing has an annular contact end face surface proposed with the seal ring to form a dynamic fluid seal, and a seal assembly positioned within a region defined by the flared bore of the cap, a primary seal ring and a load-applying combination and secondary seal ring associated with the primary seal ring, the primary seal ring has an annular body formed of a material resistant to abrasion, rigid, but resilient and is of generally "L" shaped cross section to include the radial and axial flanges, the radial flange includes at least one axially outer end face with a portion forming a primary seal strip on the end face surface of the hub, and an axially extending radially extending internal seating surface, the axial flange having an axially extending cylindrical seating surface directed radially outwardly and a radially inwardly directed cylindrical surface positioned in relation to one of the parts of the machine, the secondary sealing ring is made of an elastomer and includes an axially external seating surface that extends generally radially in at least a partial contact with the axially internal seating surface in the primary seal ring, a radially inwardly cylindrical surface seated in the pe axial seal of the primary seal ring, a sloping surface extending radially outwardly and to the end face of the enlarged hole and a radially outer cylindrical surface which comes into contact with the cylindrically enlarged perforation, further including the seal assembly a a flexible abrasive eliminating edge extending axially outwardly from the body of the secondary seal ring and up to sealing contact with a portion of the bushing which is radially outwardly of the primary seal band.