Abstract:
A valve stem seal assembly in an internal combustion engine includes a cylinder head including an aperture therein in communication with a cylinder bore and a recessed pocket surrounding the aperture. A valve guide is received in the aperture and a valve stem is received in the valve guide. A valve seal support includes a radially outwardly extending flange disposed against a surface of the cylinder head external to the recessed pocket and a cylindrical body that extends into the recessed pocket. A valve spring contacts the flange and a resilient seal is secured to the rigid valve seal support and in sealing engagement with the valve stem.

Description:
FIELD 
     The present disclosure relates to valve stem seals and more particularly, to a low profile valve stem seal. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Valve stem seals are known in the art. The valve stem seals are used to keep oil from being drawn into the combustion chamber or into the exhaust manifold from around the valve stem. If leakage is allowed to occur an increase in oil consumption of the vehicle and an impairment of proper engine performance as specified by manufacturers can result. 
     Generally speaking a valve stem seal assembly includes a rigid shell to secure a seal body on a valve stem guide, with the inside diameter of the shell engaging the outside diameter of the guide. The shell usually supports a sealing element which is centered about the valve stem in order to meter the oil that lubricates the guide inner diameter valve stem interface yet limit oil or liquid from being drawn into a combustion chamber or exhaust chamber. 
     Current valve stem seal designs are relatively tall which places design constraints on the cylinder head and other engine components. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     A low profile valve stem seal assembly is provided for use in an internal combustion engine. The valve stem seal assembly includes a cylinder head including an aperture therein in communication with a cylinder bore and a recessed pocket surrounding the aperture. A valve guide is received in the aperture and a valve stem is received in the valve guide. A valve support includes a radially outwardly extending flange disposed against a surface of the cylinder head external to the recessed pocket and a cylindrical body that extends into the recessed pocket. A valve spring seats against the flange and a resilient seal is secured to the rigid valve support and in sealing engagement with the valve stem. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  shows a cross-section of a valve stem seal assembly according to the principles of the present disclosure; 
         FIG. 2  shows a cross-section of the valve stem seal assembly according to a second embodiment of the present disclosure; and 
         FIG. 3  shows a cross-section of the valve stem seal assembly according to a third embodiment of the present disclosure. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
     When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated  90  degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     With reference to  FIG. 1 , a valve stem seal assembly  10  is shown for use in an internal combustion engine  12 . The internal combustion engine  12  includes a cylinder head  14  having an aperture  16  extending therethrough. A valve guide  18  is disposed in the aperture and receives a valve stem  20  that is supported by the valve guide  18 . A recessed bore  22  is disposed concentric with the aperture  16  in a surface  24  of the cylinder head  14  that is opposite the cylinder of the engine block (not shown). The depth of the recessed bore  22  can vary depending upon a desired application. 
     The valve stem seal assembly  10  includes a seal support  30  having a generally cylindrical body portion  32  that is received the recessed bore  22  and a radially extending flange portion  34  that is external to the bore  22  and is disposed against the surface  24  of the cylinder head  14 . A valve spring  36  is disposed against the flange portion  34 . A spring pilot  38  can extend axially from the flange portion  34  in a direction opposite the bore  16  so as to provide a pilot for the valve spring  36 . A resilient seal  40  is provided at an inboard end of the cylindrical body  32  and includes seal lip  42  that engages the valve stem  20 . The resilient seal  40  can include a recessed groove  44  that receives a seal spring  46  for applying additional force against the valve stem. The shape of the seal  40  can vary in shape depending upon the application. 
     In the embodiment shown in  FIG. 1 , the cylindrical body portion  32  and the radially extending flange portion  34  are integrally formed as a unitary body  48  along with the spring pilot  38 . The unitary body  48  can be formed from a metal sheet or from a tubular member or can otherwise be molded or formed using other known techniques. Alternatively, as illustrated in  FIGS. 2 and 3 , the radial flange portion  34  and the cylindrical body portion  32  can be formed separately. According to a first alternative embodiment as shown in  FIG. 2 , the cylindrical body portion can include a radially outwardly extending lip portion  50  that engages the radially extending flange portion  34 ′ to maintain the axial alignment therebetween while allowing rotation of the radially extending flange portion  34 ′ relative to the cylindrical body portion  32 ′. In this embodiment, the spring pilot  38 ′ can be formed by the flange portion  34 ′, the cylindrical portion  32 ′ or both. 
     As a further alternative, in the embodiment as shown in  FIG. 3  the radial extending flange portion  34 ″ can include a radially inwardly extending lip  66  that engages the cylindrical body portion  32 ″ that coaxially aligns the cylindrical body portion  32 ″ and the radial extending flange portion  34 ″ while allowing relative rotation therebetween. It is noted that during operation of the engine, certain harmonics can be achieved that cause rotation of the valve spring, thereby causing rotation of the radially extending flange. The embodiments of  FIGS. 2 and 3  allow rotation of the radially extending flange portion  34 ′,  34 ″ without causing an associated rotation of the cylindrical body portion  32 ′,  32 ″. 
     With the design of the present disclosure, the valve stem steal assembly has a generally inverted configuration as compared to conventional valve stem seal assembly. This inverted configuration allows the valve stem seal assembly  10  to take a lower profile, thus allowing greater design flexibility with regard to the thickness of the cylinder head walls, as well as allowing a reduced length of the valve guide  18  thereby reducing the amount of valve guide material and the friction between the valve guide  18  and valve stem  20 . 
     The recessed seal configuration also allows engine oil to pool inside the cylindrical body portion  32 ,  32 ′,  32 ″ above the seal  40  when the engine  12  is not in operation. Therefore, during startup of the engine  12 , oil is immediately available to provide necessary lubrication between the valve stem seal  10  and valve stem  20  whereas conventional valve stem seals typically operate initially with little or no lubrication until the lubrication is properly distributed during operation of the engine. 
     The design of the present disclosure also provides reduced overall valve seal assembly height as only a small section is needed for the spring pilot  38  that extends from the base of the spring pocket past the top of the cylinder head surface. The present design further reduces the material needed for the valve stem seal design, thus providing lower cost. The design also provides more design freedom to place the desired thickness of the cylinder head between the intake/exhaust port in the valve train deck further up in the vertical direction to gain more wetted perimeter for the incoming or exiting mass flow to or from the cylinder. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.