Abstract:
A valve seal has a sealing lip and a compressible portion. The valve seal is utilized to seal a valve guide and a stem. The valve guide has a height within a predetermined range of heights and the sealing lip sealingly engages the stem. The compressible portion has at least two articulating portions with a hinge portion between the two articulating portions. The compressible portion sealingly engages the valve guide and articulates to accept the valve guide without substantially deforming the lip or interfering with the stem.

Description:
TECHNICAL FIELD 
     The embodiments described herein are generally directed to valve stem seals, and more particularly to a valve guide seal. 
     BACKGROUND 
     In conventional overhead-valve internal combustion engines, at least two valves reciprocate to provide intermittent communication between intake and exhaust manifolds and a combustion chamber. The valves include valve stems commonly disposed in valve stem guides supporting axial motion of the valves in an engine component such as an engine head. Lubrication is provided to upper portions of the valve stems by a spray of lubricating oil within a valve cover disposed over the engine head or by gravity flow from an associated rocker arm. Oil flows by the force of gravity and may be encouraged by a pressure differential between the manifold and crankcase along a free upper end of the valve stem toward the manifolds and valve heads. 
     Valve guide seals located between the valve stem and the valve guide serve various purposes. First, they minimize engine oil consumption by restricting oil entry into the manifold and the combustion chamber. Second, they help to minimize exhaust particulates that contribute to pollution. Third, they are helpful in minimizing guide wear, which is of particular importance with diesel engines due to the nature of their operation. 
     However, current valve seals do not account for valve guide height tolerances. If a valve guide height exceeds the specified tolerance for the associated valve seal, the seal may be deformed. Thus, the sealing of the valve stem and valve guide is compromised. Deformation of the valve seal typically occurs when the height of the valve guide is out of tolerance. Due to the increased height, the valve guide seal is compressed between a retainer and the valve guide. 
     Therefore, it is desirable to provide a valve seal that allows for various tolerance valve guides. Further, it is desirable that the valve seal not interfere with the action of the valve stem. It is further desirable that a single valve stem seal may be used for a variety of valve guides having multiple heights, thus allowing for the use of the same valve seal in multiple components. 
     SUMMARY 
     Provided is a valve seal for sealing a valve guide and a stem. The valve guide has a height within a predetermined range and the valve seal comprises a sealing lip for sealingly engaging the stem, a compressible portion sealingly engaging the valve guide and articulating to accept the valve guide without substantially deforming the lip or interfering with the stem. 
     Further, a valve seal is provided for sealing a stem and a valve guide comprising a body of resilient material, a sealing lip on an inner portion of the body for sealing the stem, and a collapsible portion engaging the valve guide and adjusting in height to the valve guide. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and inventive aspects of the present invention will become more apparent upon reading the following detailed description, claims, and drawings, of which the following is a brief description: 
         FIG. 1  is a partial cross-sectional view of a sealing system having an articulating valve guide seal for a valve stem and valve guide. 
         FIG. 2  is a partial cross-sectional view of a sealing grommet for the sealing system of  FIG. 1 , according to an illustrative embodiment. 
         FIG. 3  is an enlarged, fragmentary cross-sectional view of an illustrative embodiment of a sealing portion of the sealing grommet taken from area  3  in  FIG. 2 . 
         FIG. 4  is an enlarged, fragmentary cross-sectional view of an articulating portion of the sealing grommet taken from area  4  in  FIG. 2 . 
         FIG. 5A  is a partial cross-sectional view of the articulating portion of  FIG. 4  when used with a guide of a first height. 
         FIG. 5B  is a partial cross-sectional view of the articulating portion of  FIG. 4  when used with a guide of a second height. 
         FIG. 5C  is a partial cross-sectional view of the articulating portion of  FIG. 4  when used with a guide of a third height. 
         FIG. 5D  is a partial cross-sectional view of the articulating portion of  FIG. 4  when used with a guide of a fourth height. 
         FIG. 5E  is a partial cross-sectional view of the articulating portion of  FIG. 4  when used with a guide of a fifth height. 
         FIG. 5F  is a partial cross-sectional view of the articulating portion of  FIG. 4  when used with a guide of a sixth height. 
         FIG. 5G  is a partial cross-sectional view of the articulating portion of  FIG. 4  when used with a guide of a seventh height. 
         FIG. 5H  is a partial cross-sectional view of the articulating portion of  FIG. 4  when used with a guide of an eighth height. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, illustrative embodiments are shown in detail. Although the drawings represent the embodiments, the drawings are not necessarily to scale and certain features may be exaggerated to better illustrate and explain an innovative aspect of an embodiment. Further, the embodiments described herein are not intended to be exhaustive or otherwise limit or restrict the invention to the precise form and configuration shown in the drawings and disclosed in the following detailed description. 
       FIG. 1  illustrates an embodiment of a valve seal  10 . When installed, valve seal  10  surrounds a stem  12  and provides a sealing action. A spring  14  surrounds valve seal  10  and provides a sealing compression force. Valve seal  10  is held in place by a retainer  16  attached to a non-moving component (not shown). A valve guide  18  surrounds stem  12  and includes an upper sealing surface  19 . 
     Retainer  16  is configured as a clip to hold valve seal  10  in place. Retainer  16  interfaces with valve seal  10  at a retainer seat  20  (also see  FIG. 4 ) that circumferentially surrounds valve seal  10 . Valve seal  10  is held in place by upper retainer portion  22  and a lower retainer portion  24 . Because valve seal  10  is made of resilient material and is deformable, it is installed within retainer  16  by deforming it until retainer  16  is seated around retainer seat  20 . 
       FIG. 2  illustrates in detail valve seal  10 . Valve seal  10  includes a stem sealing portion  3  (illustrated in enlarged detail in  FIG. 3 ) and a guide sealing portion  4  (illustrated in enlarged detail in  FIG. 4 ). Stem sealing portion  3  functions, among other things, to seal around the outer circumference of stem  12 . Guide sealing portion  4  functions to seal around the top of valve guide  18 . 
       FIG. 3  is an enlarged, fragmentary cross-sectional view of a first illustrative embodiment of sealing portion  3 . Sealing portion  3  is configured with a sealing lip  30  to seal stem  12  when in motion. Further provided is a spring seat  32  that circumferentially surrounds sealing lip  30  and provides a mounting groove in which to locate spring  14 . Spring seat  32  is positioned between a top  34  of valve seal  10  and upper retainer portion  22 . Spring  14  provides a compressive force substantially around sealing lip  30  and forces sealing lip  30  against stem  12   
     Referring now to  FIGS. 2 and 4 , an illustrative embodiment of guide sealing portion  4  of valve seal  10  is shown. Guide sealing portion  4  includes a first articulating portion  40 , a foot portion  42 , a first hinge  44 , a second articulating portion  46 , a second hinge  48 , and a third articulating portion  50 . First articulating portion  40  (also known as the “guide lip” of valve seal  10 ) is configured to have an offset biased toward the inside of valve seal  10  (i.e., toward stem  12  when installed). Foot portion  42  is a generally planar portion extending from first articulating portion  40  to first hinge  44 . First hinge  44  is located between first articulating portion  40  and second articulating portion  46  and is configured to allow for first articulating portion  40  to fold when compressed. Thus, first hinge  44  allows first articulating portion  40  to swing towards second articulating portion  46 . In this embodiment, first hinge  44  has its hinging side oriented towards the outside of valve seal  10 . 
     Similarly, second hinge  48  is disposed between second articulating portion  46  and third articulating portion  50 . When compressed, second hinge  48  allows second articulating portion  46  to fold over towards third articulating portion  50 . In this embodiment, second hinge  48  has its hinging side oriented towards the inside of valve seal  10 . Because first hinge  44  and second hinge  48  having hinging sides opposite each other, they are configured for accordion-like collapsing when compressed. 
     Third articulating portion  50  connects guide sealing portion  4  with lower retainer portion  24  (which is non-moving). Thus, when valve guide  18  is installed, it will press upwardly upon guide sealing portion  4  and compress it between valve guide  18  and lower retainer portion  24 . Further, foot portion  42  of guide sealing portion  4  is configured to seal against valve guide  18  when installed (as explained in detail below with respect to  FIGS. 5A-5E ). 
       FIGS. 5A-5H  illustrate valve seal  10  in use with valve guides  18  having various heights. More specifically, distances A, B, C, D, E, F, G, and H shown in  FIGS. 5A-5H , respectively illustrate decreasing distances between valve guide  18  and retainer seat  20  (i.e. the distances are A&gt;B&gt;C&gt;D&gt;E&gt;F&gt;G&gt;H). These decreasing distances correspond to increasing heights for valve guide  18  (i.e.,  FIG. 5A  illustrates a shorter valve guide  18  than  FIG. 5H ). Thus, by way of example, the function of guide sealing portion  4  is shown. 
       FIG. 5A  shows valve seal  10  in a first installed position where sealing lip  30  seals valve seal  10  to stem  12  and where first articulating portion  40  seals valve seal  10  to valve guide  18 . Valve guide  18  is installed from below and engages guide sealing portion  4  at first articulating portion  40 . Valve guide  18  is of a predetermined height and allows for the slight compression of lower guide sealing portion  4 . Here, valve guide  18  is of a height that compresses guide sealing portion  4  to a distance A between valve guide  18  and retainer seat  20 . Further, the compression seals valve guide  18  against first articulating portion  40 . 
     At compression distance A, first hinge  44  provides for only minor folding of first articulating portion  40  and second articulating portion  46 . Similarly, only minor folding of second articulating portion  46  and third articulating portion  50  is provided by second hinge  48 . Indeed, at the maximum compression distance A, valve guide  18  is only minimally compressed beyond the uninstalled configuration so that the predetermined sealing force of first articulating portion  40  against valve guide  18  is maintained. 
       FIG. 5B  shows valve seal  10  where valve guide  18  is installed to provide guide sealing portion  4  with a height B. At compression distance B, a more pronounced folding of first articulating portion  40  toward second articulating portion  46  is shown. Further, only slight folding of second articulating portion  46  (near second hinge  48 ) towards third articulating portion  50  is shown. The seal between guide sealing portion  4  and valve guide  18  is now transitioning from first articulating portion  40  to foot portion  42 . 
       FIG. 5C  shows valve seal  10  where valve guide  18  is installed to provide guide sealing portion  4  with a height C. At compression distance C, a more pronounced folding of first articulating portion  40  towards second articulating portion  46  is noticeable. Further, the seal between guide sealing portion  4  and valve guide  18  is now transitioned to the outer surface of foot portion  42 . 
       FIG. 5D  shows valve seal  10  where valve guide  18  is installed to provide guide sealing portion  4  with a height D. At compression distance D, sealing function remains between foot portion  42  and valve guide  18 . However, first articulating portion  40  is folded toward second articulating portion  46  more so than in  FIG. 5D . 
       FIG. 5E  shows valve seal  10  where valve guide  18  is installed to provide guide sealing portion  4  with a height E. At compression distance E, first hinge  44  and second hinge  48  are continuing to close. 
       FIG. 5F  shows valve seal  10  where valve guide  18  is installed to provide guide sealing portion  4  with a height F. At compression distance F, first articulating portion  40  is nearly touching second articulating portion  46 . First hinge  44  is thus nearly fully closed. Second hinge  48  is substantially closed. 
       FIG. 5G  shows valve seal  10  where valve guide  18  is installed to provide guide sealing portion  4  with a height G. At compression distance G, first articulating portion  40  is compressed against second articulating portion  46  and first hinge  44  is completely closed. Second hinge  48  is nearly completely closed and third articulating portion  50  is nearly touching second articulating portion  46 . Notably, the sealing of guide sealing portion  4  and valve guide  18  remains at foot portion  42 . 
       FIG. 5H  shows valve seal  10  where valve guide  18  is installed to provide guide sealing portion  4  with a height H. At compression distance H, guide sealing portion  4  is at the maximum allowable height for valve guide  18 . Guide sealing portion  4  is fully articulated in an accordion-like manner where first articulating portion  40  is folded against second articulating portion  46  that is in turn folded against third articulating portion  50 . Thus, valve guide  18  should not be installed where a distance less than H is provided guide sealing portion  4 . If this occurs, the seal between foot portion  42  and valve guide  18  may be lost. Additionally, due to the force of valve guide  18  against guide sealing portion  4 , retainer  16  may become pulled from retainer seat  20 . Therefore, valve seal  10  may no longer be functional. 
     Referring to  FIGS. 5A-5H , the accordion-like folding action of guide sealing portion  4  is illustrated through a maximum distance A to a minimum distance H. Valve guide  18  may be installed wherein the tolerances for height are significantly greater than standard guide seals would allow. Because valve seal  10  has the above-described articulating features, a valve guide of variable height may be used without degradation of performance. Further, because multiple heights are allowable, the same valve seal  10  may be used for multiple parts and programs. 
     Additionally, the folding action of guide sealing portion  4  allows for the variability in valve guide  18  height without interfering with retainer  16 , valve guide  18 , or stem  12 . As illustrated in  FIGS. 5A-5H , the full range of accordion-like compression is allowed without contact with retainer  16  or stem  12 . Guide sealing portion  4  folds neatly around, but not touching, stem  12 . Further, guide sealing portion  4  folds neatly within retainer  16 . As shown, even when guide sealing portion  4  is fully articulated, foot portion  42  provides a seal between valve seal  10  and valve guide  18 . 
     Herein, valve seal  10  in an illustrative embodiment that includes a bellows-shaped sealing lip (illustrated in detail with respect to  FIG. 4 ) adapted to seal the top of valve guide  18  allowing for the sealing of valve guide  18 , subject to a high guide height tolerance. The embodiment is capable of absorbing a relatively high guide height tolerance by folding in accordion-like fashion around the valve stem, thereby maintaining a sealing function against the valve guide. 
     The preceding description has been presented only to illustrate and describe exemplary embodiments of the methods and systems of the present invention. It is not intended to be exhaustive or to limit the invention to any precise form disclosed. It will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. The invention may be practiced otherwise than is specifically explained and illustrated without departing from its spirit or scope. The scope of the invention is limited solely by the following claims.