Patent Publication Number: US-2019186632-A1

Title: Integrated debris barrier on metal face seals

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to face seal assemblies, and more particularly relates to face seal assemblies having an integrated abrasive debris barrier. 
     BACKGROUND 
     Face seal assemblies are a type of mechanical seal. Face seal assemblies are used in many types of industrial equipment, including trucks and track-type machines, near relative rotating components of the equipment, such as track roller assemblies, idler assemblies, final drive assemblies, axle assemblies, etc. These seals are designed to protect underlying components, such as bearings, by keeping out debris and by preventing leakage of protective lubricants. Such equipment typically operates in environments that are highly destructive to seals and consequently to the underlying bearings. 
     Face seal assemblies usually include a pair of contacting seal rings formed of metal or other durable, hard material. The seal rings rotate relative to one another in face-to-face contact to provide a positive face seal. One of the seal rings is considered a dynamic seal ring and is associated with a rotating portion of the equipment. The other seal ring is considered a stationary seal ring and is associated with a stationary portion of the equipment. Each of the seal rings may be axially-movable relative to its associated portion. 
     There are a variety of face seal assembly designs. Typically, the seal rings are biased together by a resilient load ring, such as a toric or rectangular shaped ring. One type of face seal is a conventional Duo-Cone seal which includes a resilient load ring that is positioned on an angled portion of each seal ring to provide a force to bias the seal rings toward each other to maintain constant sealing engagement. While face seal assemblies provide a barrier to dirt, mud, and other debris, some deterioration of the metal face seals is inevitable due to the ingress of environmental abrasive particulates, such as air-borne dust, into the seal interface. 
     German Patent Application No. DE 102012012085 A1 to Zutz et al. is directed to a mechanical drive seal assembly having two slide rings, one of which is stationary (the counter ring) and one that rotates (the slip ring). The two sliding rings are each a part of a mechanical drive gasket, and mounted in two opposing housings. The sliding surface of the sliding ring and sliding surface of the counter ring are pressed tightly together, and are planar-lapped to ensure a tight fit against each other. Elastomeric rings are typically made of a high quality synthetic rubber, and are used to apply force which holds the sliding rings in tight contact with each other. There is a groove for catching dirt produced by a cut if the sliding surfaces in the outer region of the slip rings, the geometrical shape of which is intended to catch dirt and water that may easily be cleaned from the slip rings. A groove with a deliberately open trapezoidal shape is described. 
     SUMMARY 
     In an exemplary embodiment, a sealing assembly includes a first metal seal ring having a first lateral face defining a first seal surface, and a laterally-facing groove in the first lateral face, the laterally facing groove positioned radially outward of the first seal surface; a second metal seal ring including a second lateral face defining a second seal surface that is configured to form a face-to-face seal with the first seal surface; and an annular debris barrier configured to be received within the groove. 
     In another exemplary embodiment, a method of sealing between a rotating metal seal ring and a stationary metal seal ring includes creating a first debris barrier by forming a metal-to-metal face seal between the two metal seal rings; and creating a second debris barrier by capturing a barrier material between the two metal seal rings at a position radially outward of the first debris barrier. 
     In another exemplary embodiment, a drive assembly includes a stationary housing; a rotatable housing; a first metal seal ring attached to the stationary housing, the first metal seal ring including a first lateral face defining a first seal surface, and a laterally-facing groove in the first lateral face, the laterally facing groove positioned radially outward of the first seal surface; a second metal seal ring attached to the rotatable housing for rotation therewith, the second metal seal ring including a second lateral face defining a second seal surface that is configured to form a face-to-face seal with the first seal surface; and an annular debris barrier configured to be received within the groove. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages of the invention will become apparent from the description of embodiments using the accompanying drawings. In the drawings: 
         FIG. 1  is a cross-section view of an exemplary embodiment of a drive assembly according to the present disclosure; 
         FIG. 2  is cross-section view of the drive assembly as indicated in  FIG. 1 , enlarged in the area of a face seal; 
         FIG. 3  is a cutaway view of an exemplary embodiment of a seal ring of the face seal of  FIG. 2 ; 
         FIG. 4  is a cutaway view of an exemplary embodiment of a seal assembly according to the present disclosure; and 
         FIG. 5  is a cross-section view of a debris barrier of the seal assembly of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a cross section of an exemplary embodiment of a drive assembly  100 . The drive assembly  100  may contain a rotatable housing or component  104 , a stationary housing or component  102 , a stationary member  404 , such as for example, a wheel shaft, and one or more roller bearing assemblies  502 . While the exemplary embodiment is illustrated as a drive assembly, the disclosed seal assemblies may be used in any application track where a metal face seal may be used, such as, but not limited to roller assemblies, idler assemblies, final drive assemblies, axle assemblies, and the like. 
     The rotatable housing  104  of the drive assembly  100  is positioned to rotate about the stationary member  404 . The one or more roller bearing assemblies  502  may be positioned between the rotatable housing  104  and the stationary member  404  to facilitate rotation of the rotatable housing  104  relative to the stationary member  404 . 
     The drive assembly  100  may include one or more sealing assemblies positioned at interfaces between the rotatable housing  104  and the stationary housing  102  and/or stationary member  404 . The one or more sealing assemblies may be configured in a variety of ways. In some embodiments, the sealing assemblies are configured as metal face seal assemblies or floating seal assemblies. In the exemplary embodiment, the sealing assemblies include a first metal face seal assembly  106  and a second metal face seal assembly  504  positioned inward of the first metal face seal assembly  106 . The first and second metal face seal assemblies  106 ,  504  may be configured substantially the same. Thus, the description of the first metal face seal assembly  106  applies equally to the second metal face seal assembly  504 . In other embodiments, however, the first metal face seal assembly  106  is configured differently from the second metal face seal assembly  504 . 
     The first metal face seal assembly  106  may include a first metal seal ring  110  connected to the rotatable housing  104 , a second metal seal ring  112  connected to the stationary housing  102  or stationary member  404  and one or more annular debris barriers  802  ( FIG. 4 ). The first metal seal ring  110 , the second metal seal ring  112 , and the annular debris barrier  802  may be configured in a variety of ways, such as for example, different dimensions, shapes, and arrangement orientation relative to each other. In the illustrated embodiment, the first metal face seal assembly  106  has one annular debris barrier  802 . In other embodiments, the first metal face seal assembly  106  may have two, three, four, or more annular debris barriers  802 . Each of the annular debris barriers  802  may be received in a separate groove or recess. For example, a second groove adjacent or two or more debris barriers may be positioned within a single groove or recess. 
       FIG. 3  illustrates an exemplary embodiment of a cross-section of a portion of the first metal seal ring  110 . In the exemplary embodiment, the second metal seal ring  112  may be substantially the same as the first metal seal ring  110 . Thus, the description of the first metal seal ring  110  may apply equally to the second metal seal ring  112 . In other embodiments, however, the first metal seal ring  110  and the second metal seal ring  112  may have different configurations. 
     The first metal seal ring  110  is generally annular and may include a radially inward facing surface  710 , a radially outward facing surface  712  opposite the radially inward surface  710 , a first lateral face  704  extending between the radially inward surface  710  and the radially outward surface  712 , and a second lateral face  714  opposite the first lateral face  704 . The first lateral face  704  includes a seal surface  708  configured to engage and form a metal-to-metal face seal with the second metal seal ring  112 . The radially outward facing surface  712  may include a recess  726  adjacent or near the second lateral face  714  for receiving a toric  806  ( FIG. 4 ). 
     The first metal seal ring  110  has cross section with an overall height H 1  and an overall width W 1 . In the exemplary embodiment, the overall width W 1  of the first metal seal ring  110  is greater than the overall height H 1 . In other embodiments, however, the overall width W 1  of the first metal seal ring  110  may be equal to or less than the overall height H 1 . In the exemplary embodiment, the width W 1  may be in the range from about 6 mm to about 50 mm and the overall height H 1  may be in the range from about 8 mm to about 30 mm. 
     The first metal seal ring  110  may include a flange  728  extending radially outward from the radially outward facing surface  712 . The flange  728  may be positioned near or adjacent the first lateral face  704  and radially outward from the seal surface  708 . The flange  728  includes a laterally-facing groove  702  and a laterally-extending lip  706  positioned at a radially outer portion of the flange  728  (i.e., radially outward of the groove  702 ). The lip  706  includes a lateral surface  722  and a radially outward facing surface  718 . 
     While the groove  702  is described as being formed in the flange  728 , it is understood that the lateral surface  722  of the lip  706  may be considered a portion of the first lateral face  704 . Thus, describing the groove  702  as being formed in the first lateral face  704  is equally accurate. In addition, in some embodiments, the first metal seal ring  110  may not include a flange  728 , thus the groove  702  is formed in the first lateral face  704  of the first metal seal ring  110  radially inward of the radially outward facing surface  712 . 
     The groove  702  may have an interior lateral surface  716 , an upper radial surface  720 , and a lower radial surface  724 . In the exemplary embodiment, the upper radial surface  720  and the lower radial surface  724  are parallel. In other embodiments, however, the upper radial surface  720  and the lower radial surface  724  may not be parallel. 
     The dimensions of the groove  702  are configured to be sufficient to receive at least a portion of the debris barrier  802  within the groove  702 . The groove  702  may have a height H 2  and a width W 2 . In one exemplary embodiment, the height H 2  of the groove  702  may be in the range from about 0.5 mm to about 8 mm. In one exemplary embodiment, the width W 2  of the groove  702  may be in the range from about 0.5 mm to about 6 mm. 
     The lip  706  has a width W 4  and the lateral face  722  has a height H 3 . In the exemplary embodiment, the width W 4  of the lip  706  is in the range from about 1 mm to about 10 mm. In the exemplary embodiment, the height H 3  of the lateral face  722  is in the range from about 0.5 mm to about 8 mm. 
     In the exemplary embodiment, the lateral surface  722  of the lip  706  is parallel to the lateral face  704  and offset in the direction of the second lateral face  714  by a distance W 3 . In other embodiments, however, the lateral surface  722  may not be parallel to the lateral face  704 . In the exemplary embodiment, the offset distance W 3  is in the range from about 0.12 mm to about 6 mm. 
     As indicated, the second metal seal ring  112  may be substantially the same as the first metal seal ring  110 . Thus, the second metal seal ring  112  may include a first lateral surface  754 , a radially outward facing surface  760 , a seal surface  758 , a groove  752 , and a flange  768  forming a lip  756  having a second lateral surface  762 . In some embodiment, the second metal seal ring  112  does not include the groove  752 . The groove  702  in the first metal seal ring  112  may be configured to receive the entire annular debris barrier  802 . The first lateral surface  754  of the second metal sealing ring  112  may serving to capture, along with the groove  702  in the first metal seal ring  110 , the debris barrier  802  between the first and second metal seal rings  110 ,  112 . 
     Referring to  FIG. 5 , the debris barrier  802  is configured to be at least partially received within the groove  702 . The debris barrier  802  may be configured in a variety of ways, such as for example, different cross-sectional shapes, dimension, and materials used. Any configuration that may filter out fine debris, such as dust, or form a seal against enter of such debris, may be used. The cross-sectional shape of the debris barrier  802  can be any suitable shape, such as, but not limited to, circular, oval, or rectangular. The debris barrier shape  802  may have one or more curved or angled surfaces to help prevent the barrier from collapsing under the weight of debris. In the exemplary embodiment, the debris barrier  802  is annular with a cross-sectional shape that is generally T-shaped. 
     The debris barrier  802  includes a first portion  912  and a second portion  914  extending from the first portion  912 . The first portion  912  includes a first surface  916 , a second surface  910  opposite the first surface  916 , a third surface  918  extending between the first surface  916  and the second surface  910 , and a fourth surface  920  opposite the third surface and extending between the extending between the first surface  916  and the second surface  910 . 
     The second portion  914  extends from the second surface  910  and includes an end surface  922  that is opposite and the first surface  916 . In the illustrated embodiment, the second portion  914  extends perpendicularly from the first portion  912 , or from the second surface  910 . In other embodiments, however, the second portion  914  may be extend at an angle between 90 degrees and zero degrees from the first portion  912 , or from the second surface  910 . In one embodiment, the second portion  914  extends at an angle between 85 degrees and 45 degrees from the first portion  912 , or from the second surface  910 . In another exemplary embodiment, the second portion  914  is curved or includes one or more curved surfaces. 
     The debris barrier  802  may have an overall height H 5 , which is also the height of the first surface  916 , and an overall width W 5 . The debris barrier  802  may compress to some degree when captured between the seal rings  110 ,  112  or within the groove  702 . Therefore, the dimensions of the annular debris barrier  802  set forth herein, are those of the debris barrier  802  free-standing or prior to installation. 
     The overall height H 5  of the debris barrier  802  may be configured to be closely received in the groove  702  of the first metal seal ring  110 . In some embodiments, an interface fit between the overall height H 5  of the debris barrier  802  and the height H 2  of the groove  702  such that the debris barrier  802  is held in place within the groove  702 . In the exemplary embodiment, the overall height H 5  of the debris barrier is in the range from about 0.5 mm to about 8 mm. 
     As will be discussed below, the debris barrier  802  may be received within both the groove  702  of the first metal seal ring  110  and in the groove  752  of the second metal seal ring  112  when the seal rings are side-by-side in sealing engagement. Thus, the overall width W 5  of the debris barrier  802  may be configured to be closely received and captured within the two grooves  702 ,  752 . In some embodiments, an interface fit between the overall height H 5  of the debris barrier  802  and the height H 2  of the groove  702  such that the debris barrier  802  is held in place within the groove  702 . In the exemplary embodiment, the overall height H 5  of the debris barrier  802  is in the range from about 1 mm to about 12 mm. In the illustrated embodiment, the height H 8  of the flange  728  is less than the overall height H 5 . 
     The debris barrier  802  may be made from any suitable barrier material or materials capable of filtering out fine environmental abrasives and corrosives. Suitable materials for the debris barrier  802  include, but are not limited to, rubber materials such as nitrile rubbers, including NBR, HNBR, and XNBR, and felt materials, such as a polypropelyne, non-woven polyester, or combinations thereof. In one embodiment, the debris barrier  802  includes a felt material that is bound with a nitrile rubber. 
     The debris barrier  802  may form an air permeable barrier that filters out fine environmental abrasives and corrosives but allows air to pass. 
     Referring to  FIG. 4 , the face seal assembly  106  is formed by arranging the first metal seal ring  110  in a side-by-side relationship with the second metal seal ring  112  such that the lateral face  704  of the first metal seal ring  110  is adjacent the lateral face  754  of the second metal seal ring  112 . The metal seals rings  110 ,  112  may be in contact with each other near their outer circumference along their first lateral surfaces  704 ,  754 , and in particular along the seal surfaces  708 ,  758 . 
     As is known in the art, a toric  806  may be initially received in the recess  726  of each of first and second metal seal rings  110 ,  112 . Once in operation, the torics  806  may ride up onto the radially outward facing surface  712 . The torics  806  encircle the first and second metal seal rings  110 ,  112  to bias the seal surface  708  of the first metal seal ring  110  against the seal surface  758  of the second metal seal rings  112 . The engagement of the seal surfaces  708 ,  758  form a first debris barrier preventing debris from entering the interface between the rotating housing  104  and the stationary housing  102 . 
     When assembled in side-to-side relationship, the lateral surface  722  of the lip  706  on the first metal seal ring  110  faces, but is spaced apart from, the second lateral surface  762  of the lip  756  on the second metal seal ring  112 . The gap width GW of the space between lateral surface  722  of the lip  706  on the first metal seal ring  110  and second lateral surface  762  of the lip  756  on the second metal seal ring  112  forms a first debris barrier or filter that is positioned at or near the outer perimeter of the metal seal rings  110 ,  112 . The gap width GW may vary in different embodiments. In one embodiment, the gap GW is less that the width W 5  of the annular debris barrier  802 . In another embodiment, the gap width GW is less that the width W 2  of the groove  702 . In some embodiments, the gap width GW is in the range of about 0.25 mm to about 10 mm. 
     When assembled, the groove  702  in the first metal seal ring  110  faces the groove  752  in the second metal seal ring  112  to form a channel  804 . The groove  752  in the second metal seal ring  112  may be complimentary to the groove  702  in the first metal seal ring  110 . The annular debris barrier  802  is captured within the channel  804  between the first metal seal ring  110  and the second metal seal ring  112 . The annular debris seal  802  may be secured within the groove  702  in any suitable manner, such as, but not limited to, a press or interference fit, an adhesive, mechanical retention structure in the groove or on the seal, or any other suitable manner. In the exemplary embodiments, the annular debris seal  802  is press fit into one or both of the grooves  702 ,  752 . In another exemplary embodiment, the annular debris seal  802  is secured within the groove  702  by an adhesive applied to the annular debris seal  802 , within the groove  706 , or both. Any suitable adhesive may be used. 
     When the first metal seal ring  110  and the second metal seal ring  112  are biased together by the torics  806 , the annular debris seal  802  is captured and retained within the channel  804 . When received in the channel  804 , the annular debris barrier  802  may rotate with the rotating metal seal ring in relation to the stationary metal seal ring or, alternatively, the annular debris barrier  802  may remain stationary relative to the rotating metal face ring. 
     In the assembled position, the annular debris seal  802  forms a second debris barrier or filter at a position adjacent to and radially outward from the interface between the seal surfaces  708 ,  758 , but radially inward of the first debris barrier or filter formed by the space between the lateral surface  722  of the lip  706  on the first metal seal ring  110  and lateral surface  762  of the lip  756  on the second metal seal ring  112 . 
     INDUSTRIAL APPLICABILITY 
     The sealing assembly  106  may be used in any application where a metal face seal may be used. For example, the sealing assembly  106  may be used in a final drive assembly of industrial equipment, including trucks and track-type machines. The sealing assembly  106  may be used at the interface between a rotating portion of the drive assembly  100 , such as the rotating housing  104 , and a stationary portion of the drive assembly  100 , such as a stationary housing  102 . 
     The first metal seal ring  110  may be fixed to and therefore rotate with the rotatable housing  104  and the second metal seal ring  112  may be fixed to the stationary housing  102 . A metal face seal may be formed by positioning the metal seals rings  110 ,  112  in a side-by-side arrangement and applying a lateral force to one or to each of the metal seals rings  110 ,  112  to bring the seal surfaces  708 ,  758  into contact with each other. The metal face seal serves as a barrier to dirt, mud, and other debris entering the interior of the drive assembly  100 , and as a barrier to lubricating oil leaking out. 
     To enhance the life (i.e., reduce wear and corrosion) of the metal face seal, the seal assembly  106  may include two integrated debris barriers radially outward of the metal face seal. One of the debris barriers is formed by positioning the annular debris barrier  802  in the laterally-facing groove  702  formed the first metal seal ring  110  and capturing the annular debris barrier  802  in the groove  702  between the two metal seal rings  110 ,  112 . The second metal seal ring  112  may have a complimentary groove  752  that receives at least a portion of the annular debris barrier  802 . A second debris barrier is formed by creating a narrow gap between surfaces on the outer edges of the of the metal seal rings  110 ,  112 , such as the lateral surfaces  722 ,  762  on the lips  706 ,  756 . 
     The integrated debris barriers act as air filters, preventing particulates from entering the interface between the metal face seal surfaces. Further, the annular debris barrier material may block oil that may purge from the metal face seal during operation. This oil, if exposed to airborne abrasive particulates, may mix with the particulates and clog the opening and carry the abrasives into the metal face seal. 
     Integrated debris barriers also ensure that the barriers are always properly positioned to filter out particulates. Exterior, stand along barriers may not make sufficient contact with the metal face seal throughout the life cycle of the metal face assembly. 
     With the use of an integrated debris barrier, that is integrated with the metal face seal such as described in the embodiments herein, the debris barrier may maintain a better alignment and have superior followability with the metal face seal, making it more effective at filtering out debris. 
     Furthermore, the integrated debris barrier is able to leverage the sealing assembly  106  load rings (e.g. torics  806 ) to absorb relative axial motion of the sealing rings  110 ,  112 . Conversely, a non-integrated debris barrier, such as a stand-alone barrier positioned radially outward of the sealing rings  110 ,  112  would need to absorb both axial and radial motion of the system. 
     While the disclosed embodiments have been illustrated and described in detail in the drawings and foregoing description, such illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only certain exemplary embodiments have been shown and described and that all changes and modifications that come within the scope of the disclosure are desired to be protected. The disclosed embodiments are not limited to use drive assemblies, such as final drive assemblies. Rather, they may be used in any application where a metal face seal may be used, such as, but not limited to, track roller assemblies, idler assemblies, axle assemblies, and the like. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed dosing system. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed method and apparatus. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.