Patent Publication Number: US-2013228977-A1

Title: Bearing isolator

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of the filing date of U.S. Provisional Application Serial No. 61/418,434, filed Dec. 1, 2010, the disclosure of which is expressly incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates broadly to seals for sealing between a rotating shaft and its housing, and more particularly to such a seal of a bearing isolator variety including a stationary stator part and rotatable rotor part which may be snap-fit together. 
     As further described, for example, in U.S. Pat. Nos. 7,857,320 and 6,726,214, pumps, turbines, electric motors, and other machines have shafts that can rotate at a relatively high rate of speed. Such shafts are supported by at least one bearing to reduce friction. In these machines it is necessary to seal the space between the housing and the rotating shaft to prevent contaminants such as abrasive particles, moisture, or corrosive media from entering into the bearing as the service life of the bearing can be shortened by the ingress of such contaminates. It is also necessary to seal such space to inhibit oil or other lubricating fluid from leaking out of the housing. A dynamic seal that performs these functions is commonly referred to as a bearing isolator seal. 
     Bearing isolator seals conventionally are formed of a pair of ring-shaped parts that rotate with respect to each other when the shaft is rotated. One of the parts, often called the “stator” is fixed to the housing and does not rotate. The other part, often called a “rotator,” rotates with the shaft. As shown in U.S. Pat. Nos. 2,765,204; 3,109,660; 3,727,923; 4,466,620; 4,706,968; 4,743,034; 4,865,332; 4,809,941; 4,989,883; 5,069,461; 5,290,047; 5,316,317; 5,378,000; 5,431,414; 5,522,601; 5,704,719; 5,735,530; 5,967,524; 6,017,037; 6,024,362; 6,065,755; 6,113,105; 6,142,479; 6,164,657; 6,311,984; 6,336,637; 6,376,807; 6,386,546; 6,419,233; 6,471,215; 6,485,022; 6,530,573; 7,052,014; 7,521,827; 7,789,395; and 7,839,294, and in U.S. Pat. Pub, Nos. 2008/0063330 and 2008/0078648, bearing isolator seals may be of different types such as labyrinth, lip, magnetic, or brush. 
     BROAD STATEMENT OF THE INVENTION 
     The present invention is directed to a bearing isolator seal including a stator and a rotor which may be snap-fit together. An internal diffuser ring may be interposed between the stator and the rotor to direct the flow of any contaminates entering the seal out of the seal, and which may be used to set the spacing between the rotor and stator. 
     The seal of the present invention improves the exclusion and expulsion of fluids from the seal, and provides for a robust unitization between the rotor and stator parts allowing for larger sizes such as up to 12 inches (30.5 cm). The diffuser ring can provide improved capability to control the flow of any contamination that does enter the sea by directing the flow away from the interfaces at the shaft of the stator and rotor. In contrast to an internal rubber O-ring or similar seal, the diffuser ring may be made non-contacting and thus not subject to wear as a result of axial movement of the shaft. 
     The diffuser ring further may be used to provide optimal spacing between the rotor and stator during installation, and thus reducing undesired contact between the rotor and stator during initial start-up. This can result in a significant reduction in the amount of metallic dust which otherwise may develop. 
     The present invention, accordingly, comprises the design, fabrication, construction, combination of elements, and/or arrangement of parts and steps which are exemplified in the detailed disclosure to follow. Advantages of the bearing isolator seal of the present invention include improved exclusion of contaminates, and a robust unitized construction allowing for the design of larger sizes such as up to 12 inches. These and other advantages will be readily apparent to those skilled in the art based upon the disclosure contained herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings wherein: 
         FIG. 1  is a perspective view of a representative bearing isolator seal according to the present invention 
         FIG. 2  is a front elevational view of the seal of  FIG. 1 ; 
         FIG. 3  is a fragmentary, half cross-sectional view of the seal of  FIG. 2  taken through line  3 - 3  of  FIG. 2 ; 
         FIG. 4  is a magnified view of a detail of one side of the half cross-sectional view of  FIG. 3  showing the diffuser ring and snap-fit features according to the present invention; 
         FIG. 5  is a magnified view showing a detail of the other side of the half cross-sectional view of  FIG. 3  but with the diffuser ring removed and with an alternative embodiment of the snap-fit feature; and 
         FIG. 6  is a magnified view as in  FIG. 5  showing another alternative embodiment of the snap-fit feature. 
     
    
    
     The drawings will be described further in connection with the following Detailed Description of the Invention. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Certain terminology may be employed in the following description for convenience rather than for any limiting purpose. For example, the terms “forward” and “rearward,” “front” and “rear,” “right” and “left,” “upper” and “lower,” and “top” and “bottom” designate directions in the drawings to which reference is made, with the terms “inward,” “inner,” “interior,” or “inboard” and “outward,” “outer,” “exterior,” or “outboard” referring, respectively, to directions toward and away from the center of the referenced element, the terms “radial” or “horizontal” and “axial” or “vertical” referring, respectively, to directions or planes which are perpendicular, in the case of radial or horizontal, or parallel, in the case of axial or vertical, to the longitudinal central axis of the referenced element, and the terms “downstream” and “upstream” referring, respectively, to directions in and opposite that of fluid or other flow. Terminology of similar import other than the words specifically mentioned above likewise is to be considered as being used for purposes of convenience rather than in any limiting sense. In certain views of the figures, the axial or longitudinal direction may be shown by an arrow labeled “A,” and the radial direction may be shown by an arrow labeled “R.” The terms “axial” and “longitudinal” may be used interchangeably. 
     In the figures, elements having an alphanumeric designation may be referenced herein collectively or in the alternative, as will be apparent from context, by the numeric portion of the designation only. Further, the constituent parts of various elements in the figures may be designated with separate reference numerals which shall be understood to refer to that constituent part of the element and not the element as a whole. General references, along with references to spaces, surfaces, dimensions, and extents, may be designated with arrows. Angles may be designated as “included” as measured relative to surfaces or axes of an element and as defining a space bounded internally within such element therebetween, or otherwise without such designation as being measured relative to surfaces or axes of an element and as defining a space bounded externally by or outside of such element therebetween. Generally, the measures of the angles stated are as determined relative to a common axis, which axis may be transposed in the figures for purposes of convenience in projecting the vertex of an angle defined between the axis and a surface which otherwise does not extend to the axis. The term “axis” may refer to a line or to a transverse plane through such line as will be apparent from context. 
     For illustrative purposes, the precepts of the bearing isolator seal herein involved are described in connection with its use within a dynamic, rotary sealing assembly such as may be found in pumps, turbines, electric motors, and other machines or equipment having shafts that can rotate at a relatively high rate of speed. It should be appreciated, however, that aspects of the present invention may find utility in other applications. Use within those such other applications therefore should be considered to be expressly within the scope of the present invention. 
     Referring then to the figures wherein corresponding reference characters are used to designate corresponding elements throughout the several views with equivalent elements being referenced with prime or sequential alphanumeric designations, a representative bearing isolator seal according to the present invention is shown generally at  10  in the perspective view of  FIG. 1  and the front view of  FIG. 2 . As may be seen best with reference now to the cross-sectional view of  FIG. 3 , in basic construction, seal  10  includes as constituent parts a generally annular stator,  20 , and a generally annular rotor,  30 , each of which is mountable coaxially in confrontation with the other on a rotatable shaft, shown in phantom at  40 , which itself may be disposed coaxially along a common central longitudinal axis,  42 , within a bore,  44 , of an associated housing,  50 . 
     Collectively, seal  10 , shaft  40 , and housing  50  constitute a machine or other assembly which is referenced generally at  60 , with seal  10  being interposed between the shaft  40  and the bore  44  to seal the annular space or clearance, referenced at  62 , between the housing  50  and the rotating shaft  40 . Seal  10  is so provided both to prevent contaminants from entering into the housing  50  from the exterior or ambient side, referenced at  64 , of the assembly  60 , and to seal the space  62  to inhibit oil or other lubricating fluid from the leaking out of the interior or oil side, referenced at  66 , the assembly  60 . 
     Stator  20  has an outer diameter face,  70 , a forward portion of which is received coaxially in bore  44 , and an inner diameter face,  72 , mounted coaxially on shaft  40 . Stator  20  may be made stationary within bore  44  by virtue of a radial compression “press-fit” of an o-ring or similar seal,  74 , received within a corresponding circumferential groove,  76 , formed within the forward portion of outer diameter face  70 . Longitudinally, stator  20  extends along axis  42  between a first end face,  80 , disposed in bore  44  and a second end face,  82 , having a generally annular groove,  84 , formed therein, 
     With continuing reference to  FIG. 3 , rotor  30  has an inner diameter face,  86 , mountable coaxially on shaft  40 , and an outer diameter face,  88 . Rotor  30  may be retained on shaft  40  for rotation therewith by virtue of another radial compression “press-fit” of an o-ring or similar seal,  90 , received within a corresponding circumferential groove,  92 , formed within the inner diameter face  86 . Longitudinally, rotor  30  extends along axis  42  between a first end face,  94 , disposed opposite and axially spaced-apart from second end face  82  of stator  20 , and a second end face,  96 . The rotor first end face  94  has a generally annular groove,  98 , formed therein opposite the first groove  84  of the stator second end face  82 . Groove  98  has an end wall,  99 , disposed facing the stator second end face  82 . 
     A generally annular, contaminant-blocking diffuser ring,  100 , is disposed between stator  20  and rotor  20 . As may be better appreciated with additional reference to  FIG. 4  wherein the detail referenced at  102  in  FIG. 3  is depicted in enhanced detail, diffuser ring  100  extends longitudinally in having an axial length, referenced at “L” in  FIG. 4 , between a first end portion,  104 , which may be configured as a generally tapered boss, press-fit or otherwise mounted within stator groove  84 , and a second end portion,  106 , received within the rotor groove  98  in a substantially non-contacting, and thus non-wearing, relationship therewith. In this regard, the axial length L of diffuser ring  100  may be selected such that diffuser ring second end portion  106 , which may be configured as a radially outwardly-extending flange portion having one or more abutment ridges,  108   a - b , is abuttable against the rotor groove end wall  99  to define a predetermined clearance, referenced at  110 , between the stator second end face  82  and the rotor first end face  94 . Diffuser ring  100  otherwise may be configured as having a circumferential recess,  112 , formed between the first and second end portions  104  and  106  such that ring  100  may have a generally C-shaped axial cross-sectional profile. 
     With diffuser ring  100  being so provided within seal  10  and the diffuser ring second end portion  106  essentially functioning as a “bumper,” stator  20  and rotor  30  advantageously may be made to be self-aligning along, about or otherwise with the ring  100 . Moreover, with a flow path, referenced by arrow  120 , being defined between stator  20  and rotor  30 , such flow path  120  may be connected in fluid communication with the rotor and groove  98  as extending radially outwardly therefrom. 
     In service, the flow of wet or dry contaminates between the stator second end face  82  and the rotor first end face  94  thus may be directed by the diffuser ring  100  into flow path  120  for the expulsion of such contaminates out of seal  10 . Further in this regard, the rotor second end face  96  may be configured as having a angled leading edge,  130 , to assist in the deflection of contaminates to which the seal  10  may be exposed from the ambient side  64  of assembly  60  ( FIG. 3 ). Diffuser ring  100  additionally minimizes vapor flow through seal  10 . 
     A series of alternating circumferential ridges or other protrusions, one of which is referenced at  140 , and grooves, one of which is referenced at  142 , may be formed in the stator inner diameter face  72 . Such ridges  140  and grooves  142  may be provided to redirect, through centrifugal forces developed by the rotation of shaft  40 , the flow of oil or other contaminates which may enter seal  10  from the oil side  66  of assembly  60  ( FIG. 3 ) back into the housing  50  via an internal return channel,  150 . 
     Returning to  FIG. 3 , stator  20  and rotator  30  may be unitized, typically prior to their mounting on shaft  40 , by way of a snap-fit or other interlocking engagement. In this regard, stator second end face  82  may be configured has having a circumferential hook portion,  160 , which may be snap-fitted within a corresponding circumferential recess,  162 , formed within the rotor outer diameter face  88  as disposed axially between the rotor ends  94  and  96 . 
     Looking lastly now to  FIGS. 5 and 6 , the detail referenced at  170  is depicted at  170 ′ in  FIG. 5  and at  170 ″ in  FIG. 6 . Alternative configurations for the interlocking, snap-fit engagement of stator  20  and rotor  30  are shown at  160 ′ in  FIG. 5  and at  160 ″ in  FIG. 6 . 
     Materials of construction for seal  10   m  of the present invention are to be considered conventional for the applications involved. Such materials generally will be corrosion resistant and otherwise selected for compatibility with the fluid or fluids being handled and/or for desired mechanical, thermal, or other physical properties. Stator  20  and rotor  30  may be molded, cast, machined, or otherwise formed of a metal or metal alloy such as steel, stainless steel, brass, or bronze, with diffuser ring  100  being molded or otherwise formed of a fluoropolymer such as PTFE, or another plastic. Seals  74  and  90  each may be formed of a chemical-resistant elastomer such as a FKM or other fluoroelastomer. 
     As it is anticipated that certain changes may be made in the present invention without departing from the precepts herein involved, it is intended that all matter contained in the foregoing description shall be interpreted as illustrative and not in a limiting sense. All references including any priority documents cited herein are expressly incorporated by reference.