Patent Description:
Machines used in earth moving, agricultural and construction applications are subjected to extreme wear. The moving components of such machines need to be provided with a constant supply of lubrication and do so while limiting the loss of that lubrication to the environment and inflow of debris from the worksite into the lubrication supply.

A seal assembly for retaining lubricant within a sealed cavity and excluding foreign matter from the bearing surfaces between relatively moving parts disposed within the sealed cavity can be used in various components of a machine. Seals are used, for example, in a final drive system, track rollers and idlers of an undercarriage. In some examples, such as in a final drive system, a seal assembly can include a dual face seal. A dual face seal can allow a seal to be created over a rotating shaft, such as a spindle, so that one side can remain stationary and the other side can rotate and still maintain an oil seal while keeping debris out.

Over the years, a number of different configurations have been used in an attempt to provide such lubrication while preventing the loss of the lubrication and inflow of debris, such as dirt, dust and moisture into the lubrication supply. There is a need for additional improvements in preventing loss of lubrication and the inflow of debris into a sealed assembly, especially when the machines are exposed to harsh environments and challenging terrain.

One attempt to address the issue of sealing assemblies to keep lubrication in and debris out is described in <CIT>. The '<NUM> publication describes a face seal assembly including a pair of conforming seal rings having mutually-engaging seal faces. The seal faces are maintained in sealing engagement by a pair of resilient load rings having annular surfaces which engage confronting annular surfaces on the seal rings. While the '<NUM> publication provides an example of a face seal assembly design, there is room for improvement.

The present disclosure is directed to overcoming one or more of the shortcomings set forth above and/or other shortcomings in the art.

<CIT> discloses a mechanical end face seal assembly with first and second, relatively rigid, primary seal rings of a generally T-shaped cross-section and a pair of annular secondary elastomeric seal rings. The secondary rings provide a combination of radial compressive load and axial end face load and are of generally parallelogram shaped cross-section. One secondary seal member extends radially outwardly from its associated primary seal ring and the other secondary ring extends radially inwardly from its associated primary ring.

In one aspect, the present disclosure relates to a dual face seal including a seal ring having an L-shaped cross-section including an axially-extending flange and a radially-extending flange. The seal ring has an axially-extending flange and a radially-extending flange defined by a large outer diameter, a small outer diameter and an inner diameter. The seal ring further includes an annular seal face and an opposing annular loading surface. The annular seal face is configured to seal against a second seal ring in a dual face seal assembly. The annular loading surface is configured to receive a load ring. The annular loading surface includes a plurality of deformations formed in a spaced apart arrangement circumferentially around the axially-extending flange. An axial cross-section through the seal ring and intersecting one of the plurality of deformations includes a stepped geometry such that the small outer diameter has a first small diameter section and a second small diameter section, wherein a first diameter of the first small diameter section is smaller than a second diameter of the second small diameter section.

The drawings illustrate generally, by way of example, but not by way of limitation, various examples discussed in the present document.

Various examples of dual face seal assemblies having a rotary face-to-face contacting relationship via a pair of seal rings and including an improved seal ring to load ring interface are described herein. Examples described in this disclosure prevent spinning, leaking, galling and packing in the seal assembly. In addition to preventing damage, the examples described herein can also prevent debris from entering the seal.

The seal assemblies described herein minimize failures by increasing contact area and grip between a load ring having an inner annular surface and a seal ring having deformations in a loading surface to improve the ability to hold to a torque between the load ring and the seal ring.

Reference will now be made in detail to embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. The same reference numerals generally refer to the same or like components throughout the drawings. Relative terms, such as, "substantially" or "about" are used to indicate a possible variation, for example, of ±<NUM>% in a stated numeric value. As defined herein, the use of the terms "or*" or "and" includes "or", "and" or "and/or".

<FIG> illustrates a side elevational view of machine <NUM> which can include a seal assembly, in accordance with at least one example. Machine <NUM> can include a track-type drive system including a pair of continuous tracks <NUM> trained around a drive sprocket <NUM>, an idler <NUM> and rollers <NUM>, which in combination form an undercarriage. To cause the track-type drive system <NUM> to move the machine <NUM>, a motor <NUM> transfers rotational motion to a final drive system <NUM> which causes the drive sprocket <NUM> (e.g., wheel mount) to rotate. Rotation of the drive sprocket <NUM> causes the continuous tracks <NUM> to move around the drive sprocket <NUM>, idler <NUM> and rollers <NUM>, enabling movement of the machine <NUM> relative to a ground surface <NUM>. The motor <NUM> can be any suitable type of power source known in the art, including, but not limited to a diesel-powered, gas-powered, or natural gas-powered engine. The motor can also include electric powered, or hybrid power systems.

In various examples, the machine <NUM> can be any suitable machine, such as a general-purpose machine, a tractor such as an agricultural tractor, a skid steer loader, a tracked vehicle such as a military tracked vehicle, a wheel loader, a backhoe, an excavator, a material handler and the like. The machine can also be a stationary machine. While the machine <NUM> is illustrated in the context of a track-type machine, it should be appreciated that the present disclosure is not thereby limited, and that a wide variety of other machines, both those with tracks and without tracks can include features of the seal assemblies described herein.

<FIG> illustrates a cross-sectional view of the final drive system <NUM> of the machine <NUM> of <FIG> taken along line <NUM>-<NUM>' (e.g., through a longitudinal axis 108a of a spindle <NUM>), in accordance with at least one example. <FIG> shows an example of a dual face seal assembly <NUM> constructed according to principles of the present disclosure that can provide a seal between a first member <NUM>, which in the illustrated example includes a first rotating member such as a drive sprocket <NUM> or tire mount, and a second non-rotating member <NUM>, which in the illustrated example includes a housing, such as a final drive housing, that is bolted to the machine <NUM>.

The seal assembly <NUM>, which in the illustrative example is a metal-to-metal face seal assembly <NUM> (e.g., dual face assembly), is disposed in a seal cavity <NUM> (<FIG>) extending between the first member <NUM> and the second member <NUM>. In an example, the seal assembly <NUM> can be used to retain lubricant within the seal assembly <NUM> and to prevent dirt and other contaminants from entering the seal assembly <NUM>.

While the present disclosure may be implemented in the context of a final drive system <NUM> for a track-type machine <NUM>, it is not thereby limited. In other examples, a seal assembly constructed according to the principles of the present disclosure can be used in other applications where rotatory seal assemblies are used.

The first and second members <NUM>, <NUM> are rotatable relative to one another about a longitudinal axis 108a of a shaft <NUM> (e.g., spindle) with the seal assembly <NUM> providing a means for fluidly sealing the first member <NUM> and the second member <NUM> with a running seal therebetween. In an example, the second member <NUM> can include a component mounted to a frame <NUM> of the machine <NUM> or otherwise stationary with respect to the frame <NUM>, and the first member <NUM> can comprise a component which is rotatably movable with respect the second member <NUM> about the longitudinal axis 108a. In other examples, the first member <NUM> can be stationary and the second member <NUM> can be rotatable with respect to the frame <NUM>. The use of the terms "first", "second" and the like is used for convenient reference and is not limiting in any way.

The first member <NUM> is rotatable about the longitudinal axis 108a with respect to the second member <NUM>. The first member <NUM> and the second member <NUM> can be disposed in a spaced apart relationship and adjacent one another along the longitudinal axis 108a such that they are separated by a seal gap distance D (<FIG>). During use, the first member <NUM> and the second member <NUM> can move axially with respect to each other along the longitudinal axis 108a, thereby varying the seal gap distance D a specified amount.

The seal assembly <NUM> includes first and second seal rings <NUM>, <NUM> and first and second load rings <NUM>, <NUM>, which are all annular. The first and second seal rings <NUM>, <NUM> and the first and second load rings <NUM>, <NUM> are disposed in the seal cavity <NUM> between the first member <NUM> and the second member <NUM>. The first and second seal rings <NUM><NUM>, <NUM> of the seal assembly <NUM> are disposed in abutting relationship with each other.

As described herein, the first and second seal rings <NUM>, <NUM> can be substantially identical to each other. Therefore, the description of the first seal ring <NUM>, <NUM> is applicable to the second seal ring as well. Like the first and second seal rings <NUM>, <NUM>, the first and second load rings <NUM>, <NUM> can also be substantially identical to each other. Therefore, the description of the first load ring <NUM> is applicable to the second load ring <NUM> as well. However, in some examples, the seal rings <NUM>, <NUM> may not be identical and the load rings <NUM>, <NUM> may not be not identical.

The first and second load rings <NUM>, <NUM> are respectively mounted to the first and second seal rings <NUM>, <NUM>. The first and second seal rings <NUM>, <NUM> can be made from any suitable material, such as, but not limited to, metal, a metal alloy, a ceramic material and combinations thereof. The first and second load rings <NUM>, <NUM> can be made from a suitable elastomeric material such as, but not limited to nitrile, silicone, or a fluoroelastomer, and combinations thereof.

The seal assembly <NUM> provides a dual face seal in the form of first and second seal rings <NUM>, <NUM>. In the seal assembly <NUM>, the first load ring <NUM> acts as a gasket and sealingly engages the first member <NUM> and the first seal ring <NUM> to provide a fluid-tight seal therebetween. The second load ring <NUM> acts as a gasket and sealing engages the second member <NUM> and the second seal ring <NUM> to provide a fluid tight seal therebetween.

<FIG> illustrates a cross-sectional view of the first and second seal rings <NUM>, <NUM> and first and second load rings <NUM>, <NUM> taken along line <NUM>-<NUM>' in <FIG>, in accordance with at least one example. The first and second seal rings <NUM>, <NUM> can each be in the form of an annulus. The first seal ring <NUM> and the second seal ring <NUM> can abut one another such that seal faces <NUM>, <NUM> of the first seal ring <NUM> and the second seal ring <NUM> are in contacting relationship with each other.

To maintain a strong seal assembly, it is beneficial to keep the first seal ring <NUM> and the first load ring <NUM> in a fixed relationship with each other and the second seal ring <NUM> and the second load ring <NUM> in a fixed relationship with each. To provide rotation of the first member <NUM> relative to the second member <NUM>, the first seal ring <NUM> and the second seal ring <NUM> rotate relative to one another with the closest point of contact being along the first and second seal faces <NUM>, <NUM>.

<FIG> illustrates a close-up view of a portion of the example seal assembly of <FIG>. Each of the first member <NUM> and the second member <NUM> includes a load ring engagement surface (first and second load ring engagement surfaces <NUM>, <NUM>). The load ring engagement surfaces <NUM>, <NUM> of the first member <NUM> and the second member <NUM> define, at least in part, the seal cavity <NUM>, which extends axially along the longitudinal axis 108a between the first member and the second member.

The load ring engagement surfaces <NUM>, <NUM> are generally annular and are coaxial with the longitudinal axis 108a. In the illustrated example, the load ring engagement surfaces <NUM>, <NUM> each maintains the respective cross-sectional shape shown in <FIG> substantially continuously over the entire circumference circumscribed around the longitudinal axis 108a by the first and second members <NUM>, <NUM>.

As described with reference to seal ring <NUM> in <FIG>, each seal ring <NUM>, <NUM> has an L-shaped cross-section including an axially-extending flange <NUM> and a radially extending flange <NUM>. Each seal ring <NUM>, <NUM> is defined by a large outer diameter <NUM>, a small outer diameter and an inner diameter <NUM> Each seal ring <NUM>, <NUM> further includes an annular seal face <NUM>, <NUM> and an opposing annular loading surface <NUM>, <NUM> which is configured to receive the corresponding first or second load ring <NUM>, <NUM>.

Each of the seal faces <NUM>, <NUM> are defined by the radially-extending flange <NUM> which extends radially away from the longitudinal axis 108a of shaft <NUM> (shaft <NUM> not fully shown in <FIG>, also see <FIG>). The seal faces <NUM>, <NUM> of the first and second seal rings <NUM>, <NUM> form a radially-extending annulus and are in a sealing relationship with each other. Each seal face <NUM>, <NUM> can extend radially to an outer perimeter <NUM>. The first and second seal rings abut one another such that at least a portion of the first and second seal rings <NUM>, <NUM> are in contacting relationship with each other to define a band <NUM> of contact between the seal faces <NUM>, <NUM>.

Axial loading of the first and second seal rings <NUM>, <NUM> along the longitudinal axis 108a. is accomplished by means of the first and second load rings <NUM>, <NUM>. The first and second load rings <NUM>, <NUM> resiliently support the first and second seal rings <NUM>, <NUM>, respectively. First and second loading surfaces <NUM>, <NUM> are formed along the first and second seal rings <NUM>, <NUM> to receive the first and second load rings <NUM>, <NUM>, respectively. The first loading surface <NUM> is formed by radially-extending flange <NUM> and an axially-extending flange <NUM>. The second loading surface <NUM> is formed by the radially-extending flange <NUM> and a second axially-extending flange <NUM>. In this arrangement, the first load ring <NUM> engages the first loading surface <NUM> of the first seal ring <NUM>, and the second load ring <NUM> engages the second loading surface <NUM> of the second seal ring <NUM><NUM>.

The load ring engagement surface <NUM> of the first member <NUM> and the loading surface <NUM> of the first seal ring <NUM> are in confronting, spaced apart relationship such that they compress the first load ring <NUM> therebetween when in an assembled state (e.g., compressed state). The load ring engagement surface <NUM> of the second member <NUM> and the loading surface <NUM> of the second seal ring <NUM> are in confronting, spaced apart relationship such that they compress the second load ring <NUM> therebetween when in the assembled state.

In other words, the load ring engagement surfaces <NUM>, <NUM> of the first and second members <NUM>, <NUM> are positioned in corresponding confronting (e.g., opposing) relationship with respect to the loading surfaces <NUM>, <NUM> of the first and second seal rings <NUM>, <NUM> so as to contain and compress the first and second load rings <NUM>, <NUM> therebetween. Axial loading of the first and second seal rings <NUM>, <NUM> is thus accomplished through the axial loading of the first and second load rings <NUM>, <NUM> by the first and second members <NUM>, <NUM>.

The first and second load rings <NUM>, <NUM> resiliently support the first and second seal rings <NUM>, <NUM> and drive the seal faces <NUM>, <NUM> of the first and second seal rings <NUM>, <NUM> together to define the band <NUM> of contact between the seal rings <NUM>, <NUM>. The first and second load rings <NUM>, <NUM> act in the manner of a spring to apply an axial load respectively against the first and second seal rings <NUM>, <NUM> in opposing directions along the longitudinal axis 108a to bring the seal faces <NUM>, <NUM> of the first and second seal rings <NUM>, <NUM> into face-to-face sealing contact under pressure along the band <NUM> of contact such that a running, fluid tight seal is formed.

As shown in <FIG>, and as described with reference to load ring <NUM>, each of the load rings <NUM>, <NUM> can include an inner annular surface <NUM> and an outer annular surface <NUM> that are concentrically disposed about the longitudinal axis 108a. In some examples, both the inner annular surface <NUM> and the outer annular surface <NUM> of the load ring <NUM> can be substantially parallel to the longitudinal axis 108a and/or each other and extend axially. The load rings <NUM>, <NUM> can extend in an axial direction from an inner radial surface <NUM> to an outer radial surface <NUM>.

The first and second seal rings <NUM>, <NUM> are rotatably movable with respect to each other about the longitudinal axis 108a. In this arrangement, the second seal ring <NUM> can be considered a stationary seal ring as it is rotatably coupled through the second load ring <NUM> with the second member <NUM>. In contrast, the first seal ring <NUM> can be considered a rotational seal ring as it is coupled through the first load ring <NUM> with the first member <NUM>. In the example, the first member <NUM> can be a sprocket or wheel mount <NUM> (<FIG>) that is rotatably mounted to the second member <NUM> such that the sprocket or wheel mount <NUM> can rotate about the longitudinal axis 108a relative to the second member <NUM>.

As shown in <FIG>, the first load ring <NUM> engages the first loading surface <NUM> of the first seal ring <NUM>, and the second load ring <NUM> engages the second loading surface <NUM> of the second seal ring <NUM>. To ensure a long-life and good performance of the seal assembly <NUM>, it is important to prevent rotation (e.g., spinning) of the first load ring <NUM> relative to the first seal ring <NUM> at the first loading surface <NUM>. Likewise, it is important to prevent rotation of the second load ring <NUM> relative to the to the second seal ring <NUM> at the second loading surface <NUM>.

However, there continue to be challenges with preventing rotation in conventional seal assemblies. To improve seal assembly <NUM> performance and reduce the occurrence of rotation between the first load ring <NUM> and the first seal ring <NUM>, and likewise between second load ring <NUM> and second seal ring <NUM>, improved grip and resistance to torqueing at the loading surfaces <NUM>, <NUM> and the load ring engagement surfaces <NUM>, <NUM>, is desired.

As shown in the cross-section of <FIG> and with support from <FIG> which depict axial and perspective views of the seal rings <NUM>, <NUM>, to improve grip and sealing at the loading surfaces <NUM>, <NUM> (<FIG>), a plurality of deformations <NUM> are formed in spaced apart arrangement circumferentially around the seal rings <NUM>, <NUM>. The deformations <NUM> are formed in the loading surfaces <NUM>, <NUM> of the axially-extending flanges <NUM>, <NUM>. As illustrated in seal ring <NUM>, the axially-extending flange <NUM> can extend a length <NUM> from an inner end <NUM> to an outer end <NUM>. According to the invention, an axial cross-section through the axially-extending flange <NUM> and through one of the deformations <NUM> is including a stepped geometry or stepped diameter along the axially-extending flange <NUM>.

In the example of <FIG>, and as described with reference to seal ring <NUM>, the stepped geometry can be described as the first loading surface <NUM> having a stepped small outer diameter. The stepped small outer diameter includes a first small outer diameter 164a and a second small outer diameter 164b (<FIG>). Both the first and second small outer diameters 164a, 164b can be considered small compared to large outer diameter <NUM> of the radially-extending flange <NUM>.

In some examples, and as shown in <FIG>, the deformations <NUM> can be located distal from the radially extending flange <NUM> proximate the outer end <NUM>. In other examples, the deformations <NUM> can be positioned in another location along the length <NUM> of the axially-extending flange <NUM>. For example, the deformations <NUM> could be located proximate the radially-extending flange <NUM>. In some examples, the first small outer diameter 164a can extend between <NUM>-<NUM>% of the length <NUM> of the axially-extending flange <NUM>. In some examples the second small outer diameter 164b can extend <NUM>-<NUM>% of the length of the axially-extending flange <NUM>. In some examples, each of the first small outer diameter 146a and the second small outer diameter 164b extends about <NUM>% of the length <NUM> of the axially-extending flange <NUM> (each being within a range of ±<NUM>%, or possibly more preferably within a range of ±<NUM>%). The interaction of the deformations <NUM> in the seal rings <NUM>, <NUM> and the interaction with the load rings <NUM>, <NUM> will be described further in <FIG>.

In the illustrative example, the load rings <NUM>, <NUM> have a smooth inner annular surface <NUM> defined by a constant diameter <NUM> (e.g., substantially constant). The example load ring <NUM>, <NUM> does not include complementary deformations along the inner annular surface <NUM> of the load rings <NUM>, <NUM> to interface with deformations <NUM> in the seal rings <NUM>, <NUM>. Rather, in the illustrated example, the load rings <NUM>, <NUM> can include an inner annular surface <NUM> having constant diameter <NUM> (<FIG>) and a uniform inner annular surface <NUM> dimension, or at least a uniform inner annular surface <NUM> in the region of the load ring <NUM>, <NUM> that interfaces with the deformations <NUM> in seal ring <NUM>, <NUM>. In some examples, the load ring <NUM>, <NUM> may not have a completely uniform inner diameter <NUM> (<FIG>), but any deformations or non-uniformity that is present in the load rings <NUM>, <NUM> does not necessarily interface in a complementary shape and manner with the deformations <NUM> in the seal rings <NUM>, <NUM>.

Since the illustrative load rings <NUM>, <NUM> in some examples do not include complementary geometry to fill the deformations <NUM> in the seal rings <NUM>, <NUM>, when the load rings <NUM>, <NUM> are loaded onto the seal rings <NUM>, <NUM> and compressed in an assembled state (<FIG>, <FIG>) by the first and second members <NUM>, <NUM>, the load rings <NUM>, <NUM> are compressed against the seal rings <NUM>, <NUM>. Under the compressive force of the first and second members <NUM>, <NUM>, portions of the load rings <NUM>, <NUM> are distorted and deformed into (e.g., protrude into, squeeze into) the deformations <NUM>. This interface between the respective load rings <NUM>, <NUM> and the seal rings <NUM>, <NUM> can improve grip and sealing and reduce tearing of load rings <NUM>, <NUM> over conventional seal assemblies.

<FIG> illustrates an axial view of the example seal rings <NUM>, <NUM> (<NUM> is hidden from view) of <FIG>, while <FIG> is a perspective view of a portion of the seal rings <NUM>, <NUM>. Both <FIG> show the deformations <NUM> in greater detail. As defined herein, deformations <NUM> are understood to mean features which recess into a defined surface or extend outward away from a defined surface. The defined surface can include for example, a ring shape, such as the loading surface of the seal rings <NUM>, <NUM>. In <FIG>, the deformations <NUM> are shown as depressions, however the deformations <NUM> can also include raised deformations.

<FIG> illustrates an axial view of the example load ring <NUM> and seal ring <NUM> of <FIG> in an uncompressed state. <FIG> illustrates a close-up view of a portion of <FIG> both illustrate how the load ring <NUM> may not include deformations that extend into the deformations <NUM> in the seal ring <NUM>.

<FIG> illustrates a close-up view of the load ring <NUM> and seal ring <NUM> of <FIG>, but in an assembled (e.g., compressed state). In the compressed state, the load ring <NUM> is distorted such that the load ring <NUM> extends into and fills a portion of the deformations <NUM> in the seal ring <NUM>. The distortion (e.g., squeezing, pushing, stretching) of the load ring <NUM> under compression, applied by radial force Fradial (<FIG> and <FIG>) and Faxial (<FIG>), increases the surface area of the load ring <NUM> that is in contact with the seal ring <NUM>. In this arrangement, grip between the load ring <NUM> and the seal ring <NUM> are improved because the amount of surface area of the load ring <NUM> that is in contact with the seal ring <NUM> is increased. One benefit of an example including providing the load ring <NUM> without complementary deformations is that there are no small features extending radially inward from the load ring <NUM> towards the seal ring <NUM> that can be sheared off under torque between the load ring <NUM> and seal ring <NUM>.

In general, the foregoing disclosure finds utility in various industrial applications, such as in a seal assembly <NUM> of a final drive system <NUM> for a track type vehicle <NUM>, as is shown and described with reference to <FIG>. The seal assembly <NUM> can be used to provide a rotating seal over a spindle <NUM> at the connection between a final drive housing (e.g., second member <NUM>) that is mounted to a frame <NUM> of the track-type vehicle <NUM> and a rotating drive sprocket or wheel mount (e.g., first member <NUM>).

Some benefits of the seal assemblies <NUM>, including seal rings <NUM><NUM>, <NUM> and load rings <NUM>, <NUM> described herein include an improvement in torque resistance in a dual face seal assembly. The dual face seal assembly can be configured to allow an elastomeric load ring <NUM> disposed between the seal ring <NUM> and the final drive housing <NUM>, to squeeze into a plurality of deformations <NUM> in the seal ring <NUM> and to form more bonding over a larger surface area than the unstressed surface area of the load ring <NUM>, thus providing resistance to spinning of the load ring <NUM> relative to either the seal ring <NUM> or the final drive housing <NUM>.

Claim 1:
A dual face seal comprising:
a seal ring (<NUM>) having an L-shaped cross-section including an axially-extending flange (<NUM>) and a radially-extending flange (<NUM>), the seal ring (<NUM>) including the axially-extending flange (<NUM>) and the radially-extending flange (<NUM>) defined by a large outer diameter (<NUM>), a small outer diameter (164a) and an inner diameter (<NUM>), the seal ring (<NUM>) further including an annular seal face (<NUM>) and an opposing annular loading surface (<NUM>),
wherein the annular seal face (<NUM>) is configured to seal against a second seal ring (<NUM>) in a dual face seal assembly (<NUM>),
wherein the annular loading surface (<NUM>) is configured to receive a load ring (<NUM>), and wherein the annular loading surface (<NUM>) includes a plurality of deformations (<NUM>) formed in a spaced apart arrangement circumferentially around the axially-extending flange (<NUM>), characterised in that an axial cross-section through the seal ring (<NUM>) and intersecting one of the plurality of deformations (<NUM>) includes a stepped geometry such that the small outer diameter has a first small diameter section and a second small diameter section further characterised in that a first diameter (164a) of the first small diameter section is smaller than a second diameter (164b) of the second small diameter section.