FACE SEAL HAVING ELASTOMERIC RING WITH SURFACE SHAPE FOR IMPROVED SEALING

A face seal assembly includes a pair of identical metal and elastomeric rings. The metal rings are biased towards one another by the elastomeric rings when the face seal assembly is installed. The metal rings each have lapped surfaces that abut one another to create a sealing arrangement. An outside side of each elastomer ring is divided by a second inner diameter surface definingly separating a metal ring engagement side from an environmentally exposed side. The environmentally exposed side of each elastomeric ring has an annularly-shaped concave valley formed in the elastomeric ring, which is facing the concave valley of its oppositely disposed respective elastomeric ring. The concave valley starts from a first annular lip and extends to a maximum offset distance at an annular bottom of the concave valley and ends at a second annular lip. The second annular lip is disposed further back from the first annular lip.

DESCRIPTION

Field of the Invention

The present invention generally relates to face seal assemblies. More particularly, the present invention relates to a face seal assembly that uses a novel shape of the elastomeric ring surface exposed to the environmental contaminants to then advantageously improve its sealing characteristics.

Background of the Invention

A face seal (i.e. a mechanical face seal/an axial face seal) is designed to keep contaminants (i.e. dirt, mud, water, etc.) out of various rotating assemblies, such as for work vehicles. The work vehicle in which the face seal is installed may be, but is not limited to, a tracked vehicle, an excavator, a bulldozer, a heavy truck, an agricultural machine, a tunnel boring machine or a mining machine. Alternatively, face seals may be used in a conveyor, a gearbox, a mixer, a stirrer or a wind-driven power station to name just a few examples.

Many face seal designs have attempted to improve the functionality of the face seal. In particular, Zutz (U.S. Pat. No. 6,494,459) teaches an axial face seal that uses a hollow space19behind a set of sealing lips12, where the hollow space is filled with grease to function as an anti-grinding agent in case dirt was to enter the hollow space19. These designs, such as Zutz, are always fighting against dirt entering their seal designs. Unfortunately, the end region13in Zutz is rounded as dirt can be forced underneath the end region13. Also, the hollow space19creates a weakened area that under pressure can be deformed inwards to allow dirt to once enter and pass by the sealing lips12.

Vik (U.S. Pat. No. 10,226,963) teaches a face seal with an elastomeric ring14and an inner sealing ring12as best seen inFIGS. 1-4. If mud and other contaminants were to enter the seal, pressure would be created against the seal-facing wall44and cause it to separate from its adjacent surface defined by the hub-side planar wall36of the planar ring portion24of the inner sealing ring12. Once again, Vik's design is fighting against contaminants from entering rather than using the contaminants to the seal's advantage.

Contrary to references like Zutz and Vik, no one skilled in the art has created a design that uses the dirt, mud, water and other contaminants to improve the sealing characteristics of the seal rather than fight against them, to which the inventors have now accomplished and are disclosing within this teaching. Accordingly, there is a need for an improved face seal design. The present invention fulfills these needs and provides other related advantages.

SUMMARY OF THE INVENTION

The following summary of the invention is in regards to the provisional application 63/106,089, filed Oct. 27, 2020, the contents of which are fully incorporated herein with this reference.

The present invention provides an elastomeric ring with a unique surface shape that can mitigate the negative effects of mud and other substances entering a sealed space. The elastomeric ring may be part of a mechanical face seal that is installed, for example, in a work vehicle.

Referring now to the drawings of the '089 provisional application, and more particularly to FIGS. 1 and 2, there is shown an exemplary embodiment of a mechanical face seal, which may be installed in a work vehicle and generally includes a pair of metal rings and a pair of elastomeric rings holding the metal rings together. In the illustrated embodiment, each of the elastomeric rings bears on a respective one of the metal rings. The mechanical face seal is installed in a housing having a first housing part and a second housing part, with the elastomeric ring seating on respective surfaces of each housing part. The work vehicle in which the mechanical face seal is installed may be, but is not limited to, a tracked vehicle, e.g., an excavator or bulldozer, a heavy truck, an agricultural machine, a tunnel boring machine, or a mining machine. It should be appreciated that the mechanical face seal may be installed in an axle of a work vehicle or in applications other than work vehicles, such as conveyor systems. In addition to being installed in an axle, the mechanical face seal may be installed in, for example, a gearbox, a mixer, a stirrer, and/or a wind-driven power station. It should be appreciated that the previously described uses of the mechanical face seal are exemplary only, and the mechanical face seal provided according to the present invention may be used in any appropriate application.

As illustrated, the metal rings may contact one another along respective first sections. The first sections of the metal rings may be biased toward one another by the elastomeric ring, similar to known mechanical face seals. The metal rings may each include a respective second section that extends from the first section. Each of the metal rings may contact the other metal ring through lapped surfaces, with one of the metal rings being fixed and the other metal ring being rotatable. The metal rings may comprise any metal material, including but not limited to steel, aluminum, etc. The elastomeric ring may bear against both the first section and the second section of each metal ring, as illustrated.

The elastomeric ring of the mechanical face seal comprises an elastomer material, such as a polymer, that is flexible to form a seal. As illustrated in greater detail inFIG. 2, each elastomeric ring has a plurality of external surfaces. It should be appreciated that while only one of the elastomeric rings is illustrated inFIG. 2, each elastomeric ring may be similar in size and shape. One of the surfaces may abut the first section of the metal ring and another of the surfaces may partially contact the second section of the metal ring, with the elastomeric ring fitting within a corner between the first section and the second section. Another of the surfaces may face a respective housing part and be spaced therefrom, with yet another surface on the same side having a portion that is spaced from the housing part and another portion that is in contact with the housing part.

Each elastomeric ring also has at least one surface on its inner diameter that has a first end contacting one of the metal rings and a second end that is opposite the first end and contacts one of the housing parts, to seal between the metal ring and the housing part. The surface may have a first flat section including the first end and a second flat section including the second end, the first flat section and the second flat section being out-of-plane with one another. In the illustrated embodiment, the gap between the first housing part and the second housing part defines a gap axis, with the first flat section defining a first axial offset distance from the gap axis and the second flat section defining a second axial offset distance from the gap axis that is greater than the first axial offset distance, i.e., the second flat section is offset from the gap axis more than the first flat section. A valley is defined between the first flat section and the second flat section and represents a region with a maximum axial offset from the gap axis.

The surface may define a curved shape between the valley and each of the flat sections, with the surface defining a first curved section between the valley and the first flat section and a second curved section between the valley and the second flat section. In the first curved section, the surface defines a plurality of arcs each defined about a respective radius. As illustrated, the surface in the first curved section may define a first arc defined about a first radius R1extending from an imaginary center outside the material of the elastomeric ring and a second arc defined about a second radius R2extending from an imaginary center inside the material of the elastomeric ring, with the first arc and the second arc being continuous with one another so the surface is a continuous surface. In some embodiments, the second radius R2defining the second arc is greater than the first radius R1defining the first arc. In contrast to the curvature of the surface in the first curved section, the surface may define a curvature in the second curved section between the valley and the second flat section that is defined by one or more arcs each having a respective radius that extends from an imaginary center outside the material of the elastomeric ring. As illustrated, the surface in the second curved section may define a third arc having a respective radius R3that meets a linearly tapered section located between the third arc and the second flat section.

By forming the external surfaces of the elastomeric rings with both a complex curvature in the first curved section and a simple curvature in the second curved section, the elastomeric rings are able to mitigate the negative effects of mud, or other undesirable substances, into the sealed space. Mitigating the negative effects of the mud or other substances into the sealed space can ensure a long-lasting mechanical face seal that does not need to be replaced frequently, if at all, during the lifetime of the machine or other device into which the mechanical face seal is installed. The general shape of the external surfaces of the elastomeric rings address mud and other substance entry into the sealed space from outside through the labyrinth and reduce mud and other substance impact on the external diameter of the metal parts. Additionally, the shape of the elastomeric rings reduces the amount of free space inside the housing, which limits the amount of mud and other substances that can enter the housing in the first place. Thus, the shape of the elastomeric rings can reduce the amount of mud and/or other substances that enter the sealed space and reduce the detrimental effects of mud and/or other substances that enter the sealed space while maintaining a sufficient seal.

Additionally, provisional application 63/262,742 filed Oct. 19, 2021, the entire contents of which are hereby incorporated in full by this reference, shows two different embodiments of the present invention. The first embodiment is captured in pages 1-3 and the second embodiment is captured in pages 4-6. The dimensions and shapes are different between the embodiments, but the overall novelty is the same in that a valley is integrally formed in the elastomeric ring on the environmental side such that any dirt, water, mud or other contaminants can aid in sealing rather than fight against it.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1-3are of an exemplary elastomeric ring20of a face seal assembly10of the present invention.FIGS. 4-6are of an exemplary metal ring of the face seal assembly10of the present invention.FIG. 7shows the exemplary face seal assembly10using the structures ofFIGS. 1-6installed in a first housing1and second housing2illustrating the sealing separation of the oil side from the mud side.

Referring generally toFIGS. 1-7, the face seal assembly10comprises a pair of metal rings20a,20b, where each metal ring20of the pair of metal rings are identical, and a pair of elastomeric rings40a,40b, where each elastomeric ring40of the pair of elastomeric rings are identical. The pair of metal rings and the pair of elastomeric rings are configured to be disposed about a common axis of rotation3. As best seen inFIG. 7, one of the metal rings of the pair of metal rings is disposed directly opposite of the other metal ring and are abutting one another in a sealing arrangement. One of the elastomeric rings of the pair of elastomeric rings is attached to one of the metal rings of the pair of elastomeric rings, and the other elastomer ring is attached to the other metal ring.

As best shown inFIGS. 3 and 6, a cross section taken through and aligned with the common axis of rotation slices the pair of metal rings and the pair of elastomeric rings respectively defining a metal ring cross section as shown inFIG. 6and an elastomeric ring cross section as shown inFIG. 3.

Referring toFIG. 6, the metal ring cross section is L-shaped having a first section21extending perpendicularly from a second section22. The first section extends away from the common axis of rotation3and the second section extends along the common axis of rotation3. The L-shaped metal ring cross section defines an inner corner30between the first and second sections. The inner corner30can be radius or even a chamfer. The pair of metal rings are configured to be biased towards one another by the pair of elastomeric rings when the face seal assembly is in an installed state as shown inFIG. 7. Each first section of the pair of metal rings comprises a lapped surface23configured to abut one another in the sealing arrangement.

Each metal ring comprises an outer diameter surface24of the first section and an outer diameter surface25of the second section that is smaller in diameter in comparison to the outer diameter surface24of the first section. An inside side26of the first section is opposite an outside side27of the first section and an outside side28of the second section. The outside side28of the second section extends outwardly beyond the outside side27of the first section. An inner diameter side29of the second side is opposite the outer diameter24of the first section and the outer diameter25of the second section. The inner corner30connects the outside side27of the first section to the outer diameter surface25of the second section. The lapped surface23is part of the inside side26of the first section.

Alternatively, the inside side26of the first section may comprise a first angled surface31adjacent to the lapped surface23. This first angled surface31may extend fully to the inner diameter side29or may include a second angled surface32as shown herein where the second angled surface32is adjacent to the first angled surface31. Furthermore, the inner diameter side29of the second side may comprise a third angled surface33adjacent to the outside side28of the second section. Also seen are a multitude of chamfers34that prevent sharp corners. It is understood by those skilled in the art that these chamfers could also be radiuses. It will also be understood by those skilled in the art that a number of additional angled or curved surfaces could be used to form the metal ring, as this teaching is not to be limited to the exact embodiment shown herein.

Referring toFIG. 3, the elastomeric ring cross section defines an outer diameter surface41opposite an inner diameter surface42which are then disposed between an outside side43opposite an inside side44. An inner corner45connects the outside side43and the inner diameter surface42and an outside corner46connects the outer diameter surface41and the inside side44.

The outside side43of the elastomer ring is divided by a second inner diameter surface47definingly separating a metal ring engagement side48from an environmentally exposed side49. The environmentally exposed side49comprises an annularly-shaped concave valley50formed in the elastomeric ring, which is facing the annularly-shaped concave valley of its oppositely disposed respective elastomeric ring of the pair of elastomeric rings of the face seal assembly. The annularly-shaped concave valley50starts from a first annular lip51and extends to a maximum offset distance52at an annular bottom53of the annularly-shaped concave valley and ends at a second annular lip54. As shown with the arrows, the maximum offset distance52is measured parallel to the common axis of rotation. The second annular lip54is disposed further back from the first annular lip51in relation to a distance parallel to the common axis of rotation, which is true whether the elastomeric ring is the uninstalled state (FIG. 3) or in the installed state (FIG. 7).

The first annular lip51ends in a first annular flat section55and the second annular lip54ends in a second annular flat section56. Referring back toFIG. 7, the face seal assembly is configured to be disposed between a first housing part1and a second housing part2, wherein one of the housing parts rotates about the common axis of rotation in relation to the other housing part. One of the elastomeric rings40ais configured to engage and attach to the first housing part1and the other elastomeric ring40bis configured to engage and attach to the second housing part2. As shown inFIG. 3, the first annular flat section is frustoconically-shaped in an uninstalled state but then inFIG. 7is perpendicularly disposed in relation to the common axis of rotation when installed in its respective first or second housing parts in the installed state. Similarly, as shown inFIG. 3, the second annular flat section is frustoconically-shaped in the uninstalled state and then inFIG. 7is perpendicularly disposed in relation to the common axis of rotation when installed in its respective first or second housing parts in the installed state.

It is important that the first and second annular flat sections55and56are at a perpendicular angle (90 degrees) or an obtuse angle (greater than 90 degrees) in comparison to their respective mating surfaces of the metal ring or housing part. Otherwise, pressure build up from the mud and other contaminants would be able to work their way under the lips51and56, whereas a flat presenting surface that is at a perpendicular angle or an obtuse angle prevents this from occurring. In other words, one skilled in the art would not want to use a radiused or rounded end of the lips51and54as this would not work as effectively as the present invention teaches.

As can be seen inFIG. 7, the inner corner45of each elastomeric ring of the pair of elastomeric rings is configured to be disposed at the inner corner30of its respective metal ring of the pair of metal rings. Also, the second inner diameter surface47of the elastomeric ring is configured to at least partially abut the outer diameter24of the first section of the metal ring of the face seal assembly. Also, the metal ring engagement side48of each elastomeric ring is configured to at least partially abut the outside side27of the first section21of its respective metal ring.

When looking atFIG. 3, the elastomeric ring cross section is generally parallelogram-shaped in the uninstalled state. Then, when the face seal assembly10is installed in the housings as shown inFIG. 7, the elastomeric properties enable the elastomeric seal to deform and create a bias that forces the lapped surfaces of the metal rings to abut one another to create the seal between the oil side and mud side. The elastomeric ring can be made from rubber, polymers, NBR (nitrile butadiene rubber), HNBR (Hydrogenated Acrylonitrile-Butadiene Rubber), VMQ (silicone) and FKM/FPM (fluorocarbon-based fluoroelastomer and fluorocarbon rubber). The metal ring is made of metal, but can be steel, stainless steel, aluminum and cast iron.

Referring again toFIG. 3, annularly-shaped concave valley50has two surfaces, first surface57and second surface58. At the annular bottom53is a radius. It is understood by those skilled in the art that this radius may be larger or smaller. Also, the radius may be a chamfer, curve or any other shape that forms the annularly-shaped concave valley50.

Also, it is understood by those skilled in the art that surfaces57and58could be simplified into just a single surface59, as is shown inFIG. 8. Also, it will be understood by those skilled in the art that 2, 3, 4 or any number of surfaces could be used, such as shown inFIG. 11where surfaces60,61,62,63,64comprise the annularly-shaped concave valley50. Also, it will be understood by those skilled in the art that the surfaces could be curved into one flowing curve65as shown inFIG. 10. Also, it will be understood by those skilled in the art that the annularly-shaped concave valley50may be simplified into just two surfaces66and67as shown inFIG. 9. As can be appreciated by those skilled in the art, there are a multitude of variations that can be created based upon this teaching of the annularly-shaped concave valley50as this disclosure is not to be limited to the exact forms described and shown herein, but be limited by a broad interpretation of the claims in the spirit of this disclosure.

As can now be appreciated by those skilled in the art after reading this disclosure, the present invention relates to a face seal assembly that uses a novel shape of the elastomeric ring surface exposed to the environmental contaminants to then advantageously improve its sealing characteristics. This is accomplished through the annularly-shaped concave valley50that allows dirt, water, mud, debris (i.e. environmental contaminants) to create a pressure against the sealing lips51and54to increase the sealing effects.

It is also worth noting that great pressure may be created when the face seal assembly10is in use that is acting against the annularly-shaped concave valley50. Therefore, it is important that the elastomeric ring40not have voids or sections of material removed from within the elastomeric ring itself that are disposed behind the annularly-shaped concave valley50, such as pockets or other hollowed out features, as these could collapse under the immense pressure resulting in a seal failure. In other words, there is constant elastomeric material from the beginning of the annularly-shaped concave valley50to then the outside side44to ensure dimensional stability of the elastomeric ring.

Although several embodiments have been described in detail for purposes of illustration, various modifications may be made to each without departing from the scope and spirit of the invention. Accordingly, the invention is not to be limited, except as by the appended claims.

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