Patent Publication Number: US-9404378-B2

Title: Rotating seal configuration and method of sealing a rotating member to a housing

Description:
BACKGROUND OF THE INVENTION 
     The subject matter disclosed herein relates to configurations that seal a rotating member to a housing and more specifically to sealing an outermost radial portion of the rotating member to the housing. Sealing components that move relative to one another create challenges. These challenges are exacerbated when clearance between the moving components is altered based upon operational conditions of the machine as happens between a shroud of a bucket and a casing of a turbine engine, for example. Industries that rely on such seals are therefore receptive to new systems and methods that improve sealing between parts moving relative to one another. 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to one aspect of the invention a rotating seal configuration includes a housing and a rotatable member rotationally mounted relative to the housing. The rotatable member has at least one portion defining an outer perimetrical face that is configured to contact the housing during operational conditions that cause a radial dimension of the at least one portion to increase. The at least one portion has opposing axial surfaces with each of the opposing axial surfaces being dimensionally axially nearer to the other of the opposing axial surfaces immediately radially inwardly of the outer perimetrical face than a furthest part of the outer perimetrical face. 
     According to another aspect of the invention a method of sealing a rotatable member to a housing includes rotating a rotatable member relative to a housing, contacting the housing with a portion of the rotatable member and cutting a groove in the housing with the portion while preventing contact between either of opposing axial surfaces of the portion and the housing. 
     According to another aspect of the invention a turbomachine component includes a rotatable member rotationally mounted relative to a housing. The turbomachine component has a portion defining an outer perimetrical face being configured to contact the housing during some operational conditions, the portion has opposing axial surfaces that are axially nearer to one another at positions radially inwardly of the outer perimetrical face than they are at the outer perimetrical face. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  depicts a cross sectional view of an embodiment of a rotating seal configuration disclosed herein; 
         FIG. 2  depicts a cross sectional view of an alternate embodiment of a rotating seal configuration disclosed herein; and 
         FIG. 3  depicts a partial cross sectional view of a turbine engine employing a plurality of the rotating seal configurations of  FIG. 1 or 2 . 
     
    
    
     The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , an embodiment of a rotating seal configuration disclosed herein is illustrated at  10 . The rotating seal configuration  10  includes a substantially stationary housing  14  and a rotatable member  18  that is configured to rotate relative to the housing  14 . The rotatable member  18  has a portion  22  with an outer perimetrical face  26  located at the greatest radial dimensions thereof The outer perimetrical face  26  is configured to interferingly contact the housing  14  during certain operational conditions of a machine that incorporates the housing  14  and the rotatable member  18 . The portion  22  has opposing axial surfaces  30 ,  31  positioned immediately radially inwardly of the outer perimetrical face  26 . The rotating seal configuration  10  is configured such that one or both of the opposing axial surfaces  30 ,  31  is axially nearer to the other of the opposing axial surfaces  30 ,  31  immediately radially inwardly of the outer perimetrical face  26  than a furthest part  32 ,  33  of the outer perimetrical face  26 . 
     Contact between the portion  22  and the housing  14  while the rotatable member  18  is rotating causes the portion  22  to cut into the housing  14  thereby cutting an annular groove  34  into an inner radial surface  38  of the housing  14 . The cutting of the groove  34  assures that annular clearance between the outer perimetrical face  26  and the housing  14  is reduced thereby forming a dynamic seal therebetween. Materials for the housing  14  and the portion  22  may be chosen to assure that more material is removed from the housing  14  than from the rotatable member  18  during cutting. In turbine engine applications, for example, the housing  14  is often made of thin metal sheets in the shape of honeycomb cells while the rotatable member  18  is fabricated of much thicker metal. As such the honeycomb housing  14  is sacrificial and is easily cut away by the rotatable member  18  when the portion  22  comes into contact therewith. The portion  22  in a turbine engine may be part of a shroud of a bucket or one of two or more teeth in a labyrinth seal of a rotor while the housing may be a stationary outer assembly of the turbine engine or another rotatable part that rotates at a different speed than that of the portion  22 , for example. 
     Making the opposing axial surfaces  30 ,  31  nearer to one another immediately radially inwardly of the outer perimetrical face  26  than a furthest part  32 ,  33  of the rotating seal configuration  10  assures that the opposing axial surfaces  30 ,  31  do not come into contact with sides  42  of the groove  34 . Such contact, if allowed to occur could have detrimental operational effects related to frictional engagement, heating and removal of additional material from either the housing  14  or the rotatable member  18  beyond that which is necessary, for example. 
     If the interference contact between the portion  22  and the housing  14  is due to radial growth only of the rotatable member  18  the sides  42  will be substantially orthogonal to a rotational axis of the rotatable member  18 . If there is some longitudinal movement combined with the radial growth of the rotatable member  18  the sides  42  may have a frustoconical or even a curved conical shape. If a longitudinal component of motion is anticipated then the opposing axial surfaces  30 ,  31  can be made to recede axially a sufficient amount to assure they do not contact the housing  14  when cutting thereinto. It should be noted that the interference contact between the portion  22  and the housing  14  can also be due to a reduction in radial dimension of the housing  14 . 
     Angles  46  and  47  are defined between the outer perimetrical face  26  and the opposing axial surfaces  30 ,  31  respectively. In the embodiment illustrated the outer perimetrical face  26  is parallel to a rotational axis of the rotatable member  18  (it should be noted, however, that outer perimetrical surfaces that are not parallel to the rotational axis of the rotatable member  18  are also possible). The angles  46  and  47  are less than 90 degrees and are therefore acute angles. Since the rotatable member  18  in  FIG. 1  is tilted, for example, and is not perpendicular to a rotational axis of the rotatable member  18 , sides  50 ,  51  thereof are also tilted. As such, the opposing axial surface  30  can simply be an extension of the side  50  thereby defining a portion of the acute angle  46 . However, if the opposing axial surface  31  were simply an extension of the side  51  then the angle  47  would be obtuse and would measure greater than 90 degrees. Opposing axial surface  31  is therefore not an extension of the side  51  but instead is a recess in the portion  22  between the side  51  and the outer perimetrical surface  26 . Since the opposing axial surface  31  is a recess it can be made in the rotatable member  18  by removal of material from the rotatable member  18 , which is easier to fabricate than adding material to a rotatable member as is typically done. 
     Referring to  FIG. 2 , an alternate embodiment of a rotating seal configuration disclosed herein is illustrated at  110 . The configuration  110  is similar to the configuration  10  and as such similar features are numbered alike and only differences will be described in detail hereunder. The rotatable member  118  of the rotating seal configuration  110  has sides  150 ,  151  that taper together toward the outer perimetrical surface  26 . As such, both opposing axial surfaces  130 ,  131  are defined by recesses formed in the sides  150 ,  151  at a portion  122  of rotatable member  118  near the outer perimetrical surface  26 , thereby defining acute angles  146 ,  147  respectively. 
     Referring to  FIG. 3 , a portion  212  of a turbine engine  216  employing the rotating seal configuration  10 ,  110  disclosed herein. The portion  212  can be any rotating portion  212  of the turbine engine  216  including but not limited to rotational portions of a compressor section or a turbine section. The portion  212  includes a plurality of the rotating seal configurations  10 ,  110  with one configuration  10 ,  110  each being illustrated on an end  220  of one of five teeth  224 . Together the plurality of rotating seal configurations  10 ,  110  form a labyrinth seal  228  since each of the teeth  224  form one of the grooves  34  in the housing  14 . 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.