Abstract:
The present invention is an apparatus for sealing in a compressor having a compressor housing and a rotatable shaft extending through the compressor housing, with a pressure seal having a first sealing member and a first sealing lip abutting and adjacent to, respectively, said housing and rotatable shaft, and a seal guide attached to the compressor housing and extending radially inward toward the rotatable shaft for maintaining alignment of the pressure seal.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not Applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable. 
       INCORPORATION BY REFERENCE 
       [0003]    Not Applicable. 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Field of the Invention 
         [0005]    The present invention pertains to compressor sealing devices. The invention more particularly concerns a sealing device comprising a pressure seal and seal guide disposed in the annular space or cavity between a compressor&#39;s housing and rotatable shaft. 
         [0006]    2. Discussion of the Background 
         [0007]    Open compressors, such as those employed in automobile air conditioning systems, require the use of sealing mechanisms to prevent oil and coolant fluids from leaking from high-pressure compartments into lower-pressure compartments. A compressor of this type generally includes a rotating shaft which penetrates a housing structure. The sealing mechanism is disposed in the limited annular space between the shaft and the housing, and is subjected to frictional forces in areas where certain dynamic sealing surfaces slide or rub against each other as the shaft rotates—which may result in wear-and-tear to the mechanism. 
         [0008]    Any number of sealing mechanisms are known in the art which comprise, generally, one or more rubber sealing lips which abut a compressor&#39;s rotatable shaft along its periphery, one or more sealing members which may comprise sealing lips, rings or similar structures which abut and are generally attached to the inner surface of the housing, and intermediate structures made of metal or similar rigid or semi-rigid materials to which the sealing lips and sealing members are fixed. The intermediate structures, which may include brackets, washers, or cases provide support for the sealing lips and prevent deformation of the sealing mechanism. 
         [0009]    An example of the aforementioned sealing mechanism type is found in U.S. Patent Application Pub. 2001/0030398 A1 (“&#39;398”). &#39;398 includes two sealing lips for contact with the compressor shaft. A front sealing lip is designed for sealing against the shaft during operation while a second, rear sealing lip of larger diameter is designed to seal against the shaft when it is not in use, thus maintaining a seal both during and between uses. Further, &#39;398 discloses an intermediate structure which provides additional angular support to the front sealing lip allowing it to better resist deformation caused by increasing coolant pressures. This design was developed in part to address abrasion of the sealing lips of prior inventions which made sealing during periods of non-use unreliable. Said abrasion resulted from friction caused by contact between the outer surface of the shaft and the front sealing lip which increased as a result of increasing coolant fluid pressures. 
         [0010]    Similar seal mechanisms have been developed, such as that disclosed in U.S. Pat. No. 5,052,696 (“&#39;696”), to address the need for more compact compressor seals given the ever-shrinking annular spaces surrounding the rotating shaft. &#39;696&#39;s sealing mechanism comprises generally an elastomeric seal member bonded to a metal seal casing and a polytetrafluoroethylene seal member clamped to the casing against the elastomeric seal member. &#39;696&#39;s compact sealing mechanism and others of its kind were developed as a direct result of the reduction in “size and weight of virtually every component used in an automobile in order to increase fuel economy.” 
         [0011]    Other seal mechanisms of notably different design are known in the art, such as that disclosed in U.S. Pat. No. 6,322,081 (“&#39;081”). These mechanisms utilize a stationary stator mounted to the interior of the housing with a carbon ring mounted to the stator, and a rotor having a ceramic ring mounted on the shaft. The carbon and ceramic rings contact each other on radially-inward and outward facing surfaces, respectively, whereby these rings maintain a seal between high and low-pressure compartments. &#39;081 was developed in part to address concerns inherent in mechanisms of this type relating to thermal expansion of their constituent parts. Namely, seal failure and abrasion can result from utilizing rotors which expand in response to temperature changes at a different rate than their corresponding stators. 
         [0012]    A recurring problem with the sealing mechanisms listed above, and indeed with all such mechanisms, is frictional wear-and-tear (abrasion) to the surfaces of the mechanisms which slide across each other during compressor operation. Regarding those sealing mechanisms which employ rubber sealing lips (e.g. &#39;398 and &#39;696), this abrasion occurs most frequently in the area of the sealing lips which abut the rotating shaft. Mechanisms such as that disclosed in &#39;081 experience the abrasion on their radially-inward and outward facing surfaces, in the case of &#39;081 those surfaces include the carbon and ceramic rings. 
         [0013]    Attempts to combat this abrasion as well as to decrease leakage across dynamic sealing surfaces have included the application of lubricating films or coatings of oil. The oil operates to reduce friction and resulting heat which is damaging to the dynamic sealing surfaces. Unfortunately, these oils have a tendency to dry out or otherwise dissipate during periods of non-use. Following such dissipation, reinstated use of the compressor may suffer from leakage and damage to dynamic sealing surfaces. 
         [0014]    There is thus a need for a sealing apparatus which experiences reduced abrasion of its dynamic sealing surfaces while providing an acceptable seal preventing significant leakage of coolant fluids. 
       BRIEF SUMMARY OF THE INVENTION 
       [0015]    In one embodiment of the invention the apparatus is utilized in a compressor having a compressor housing and a rotatable shaft extending through the compressor housing, and comprises a pressure seal having a first sealing member and a first sealing lip abutting and adjacent to, respectively, said housing and rotatable shaft, and a seal guide attached to the compressor housing and extending radially inward toward the rotatable shaft. 
         [0016]    Another embodiment of the invention comprises a sealing device comprising a compressor housing having a front head, a rotatable shaft extending through the compressor housing, a pressure seal having a first sealing member and a first sealing lip abutting and adjacent to, respectively, said housing and rotatable shaft, and a seal guide attached to the front head and extending radially inward toward the rotatable shaft. 
         [0017]    In still yet another form of the invention the device includes a compressor housing having a front head, a rotatable shaft extending through the compressor housing, a pressure seal having a first sealing member and a first sealing lip abutting and adjacent to, respectively, said housing and rotatable shaft, a second sealing lip adjacent to the rotatable shaft, and a seal guide attached to the front head and extending radially inward toward the rotatable shaft. 
         [0018]    In still yet another form of the invention the device includes a compressor housing having a front head, a rotatable shaft extending through the compressor housing, a pressure seal having a first sealing member and a first sealing lip abutting and adjacent to, respectively, said housing and rotatable shaft, a second sealing lip adjacent to the rotatable shaft, and a seal guide comprised of oil impregnated bronze bushing attached to the front head and extending radially inward toward the rotatable shaft. 
         [0019]    The foregoing are intended to be illustrative of the invention and are not meant in a limiting sense. Many possible embodiments of the invention may be made and will be readily evident upon a study of the following specification and accompanying drawings comprising a part thereof. Various features and subcombinations of invention may be employed without reference to other features and subcombinations. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    A preferred embodiment of the invention, illustrative of the best mode in which the applicant has contemplated applying the principles, is set forth in the following description and is shown in the drawings and is particularly and distinctly pointed out and set forth in the appended claims. A more complete appreciation of the invention and many of the advantages thereof will be readily obtained as the same becomes better understood by references to the detailed description when considered in connection with the accompanying drawings, wherein: 
           [0021]      FIG. 1  is a cross-sectional side view of an embodiment of the invention having a pressure seal with two sealing lips adjacent to the rotatable shaft and a seal guide attached to the interior surface of the compressor housing. 
           [0022]      FIG. 2  is a cross-sectional side view of an embodiment of the invention having an A6 style compressor housing and seal guide attached to the front head of the compressor housing. 
           [0023]      FIG. 3  is a cross-sectional side view of an embodiment of the invention having a pressure seal with two sealing lips adjacent to the rotatable shaft and a seal guide comprised of bronze bushing attached to the front head of the compressor housing. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    As required, one or more detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the principles of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. 
         [0025]    Referring now to  FIGS. 1-3 , wherein like reference numerals designate identical or corresponding parts through the several views, an embodiment of the present invention is displayed therein. 
         [0026]      FIG. 1  is a cross-sectional side view of an embodiment of the invention. A sealing device  20  is comprised of a compressor housing  22  having an interior surface  24  which defines a housing cavity  26 . A rotatable shaft  28  extends through the housing cavity  26  and, in the embodiment of  FIG. 1 , forms a substantially cylindrical shape with an outer surface  30 . A pressure seal  32  occupies part of the housing cavity and seals against the interior surface  24  using a first sealing member  33  and against the outer surface  30  using first and second sealing lips  34 ,  36 . 
         [0027]    The first and second sealing lips  34 ,  36  shown in  FIG. 1  are comprised of elastomeric materials, rubbers, or similar materials which are known in the art for use in sealing mechanisms. The first and second sealing lips  34 ,  36  seal against the outer surface  30  by, for example, being dimensioned with smaller diameter than the outer surface  30  of the rotatable shaft  28 . In this embodiment, the first sealing member  33 , which may be comprised of elastomeric materials, inlaid ring apparatuses or other known structures for creating a seal against the interior surface  24 , abuts the interior surface  24  of the compressor housing  22  and is associated therewith or fixed thereto to provide a seal against movement of fluids from high to low pressure compartments. Other configurations and mechanisms are known in the art to achieve a seal between high and low pressure compartments of certain compressor types by utilizing at least one sealing lip, and these known sealing mechanisms may be employed in this invention without departing from its spirit and intended scope. 
         [0028]    Also shown in  FIG. 1  is a seal guide  38  which is attached to the interior surface  24  of the compressor housing  22 . The seal guide  38  extends radially inward from the interior surface  24  and is adjacent to the outer surface  30  of the rotatable shaft  28 . The seal guide  38  contacts the outer surface  30  at least intermittently during operation of the compressor. In so doing, the seal guide  38  helps to reduce normal deflection of the rotatable shaft  28 . 
         [0029]    Prior inventions merely accepted deflection of the rotatable shaft  28  as a “normal” consequence of operation of the compressor, and prior inventors have failed to adequately address deflection in the context of automobile air compressors. With the addition of this seal guide  38 , the present invention helps reduce this deflection in a manner which reduces abrasion of at least one sealing lip. Not only does the seal guide  38  increase the lifetime of a sealing mechanism in comparison with similar prior art seals which do not include seal guides, it widens the range of potential pressure seal  32  designs which may be used as part of the sealing mechanism. 
         [0030]    For example, A6 compressor models have frequently relied on the type of pressure seal which comprises a stationary stator mounted to the interior of the housing with a carbon ring mounted to the stator, and a rotor having a ceramic ring mounted on the shaft. One drawback to use of these types of pressure seals is that they commonly rely on oil to reduce abrasion of dynamic sealing surfaces. Unfortunately, these oils have a tendency to dry out or otherwise dissipate during periods of non-use. Following such dissipation, reinstated use of the compressor may suffer from leakage and damage to dynamic sealing surfaces. Through use of embodiments of the present invention, pressure seals  34  may be employed which are comprised of at least one sealing lip and which have reduced reliance on oils which may evaporate. 
         [0031]    During compressor operation, the compressor&#39;s rotatable shaft  28  rotates and its outer surface  30  is in contact with at least one of the sealing lips  34 ,  36  of the pressure seal  32 . Through the seal formed with the outer surface  30  and the seal formed by the first sealing member  33  with the interior surface  24  of the compressor housing  22 , fluid movement from the high pressure side of the seal to the low is reduced or eliminated. The seal guide  38  is in at least intermittent contact with portions of the outer surface  30  to help maintain alignment and prevent deflection. This, in turn, helps to reduce abrasion, including uneven wear and tear, of at least one of sealing lips  34 ,  36 . 
         [0032]    Referring now to  FIG. 2 , it is a cross-sectional side view of an embodiment of the invention having an altered A6 style compressor housing  22 . The depicted compressor housing  22  is further comprised of a front head  40 . The front head  40  is altered from its factory dimensions and is bored out to provide a larger diameter interior surface  24 . The seal guide  38  is attached to the interior surface  24  of the front head  40 . This embodiment of the invention provides the benefit of conserving annular space between the outer surface  30  of the rotatable shaft  28  and the interior surface  24  of the compressor housing  22  through attachment of the seal guide  38  to a bored-out section of the compressor housing  22  rather than to other portions of the compressor housing  22  as in other embodiments of the invention. Further, it is foreseen that, in a preferred embodiment, the seal guide  38  may be comprised of oil impregnated bronze bushing attached to the front head  40  of the compressor housing  22  as shown in  FIG. 2 . 
         [0033]    The rotatable shaft  28  of embodiments of the invention may be polished or burnished in order to reduce outer surface  30  irregularities which may contribute to increased abrasion of the sealing lips. The rotatable shaft  28  may be polished using, for example, a 180 degree sanding belt wrap and 400 grit sandpaper at 820 RPM&#39;s to minimize shaft seal surface peaks and valleys. 
         [0034]    Referring now to  FIG. 3 , it is a cross-sectional side view of an embodiment of the invention having a pressure seal with two sealing lips  34 ,  36  adjacent to the rotatable shaft  28  and a seal guide  38  attached to the front head  40  of the compressor housing  22 . 
         [0035]    These and other uses of, and modifications to, the present invention will be apparent to those of skill in the art upon reading this disclosure. 
         [0036]    Having now described the features, discoveries and principles of the invention, the manner in which the invention is constructed and used, the characteristics of the construction, and advantageous, new and useful results obtained; the new and useful structures, devices, elements, arrangements, parts and combinations, are set forth in the appended claims. 
         [0037]    It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall there between.