Abstract:
A sealing device primarily for sealing off a slit-shaped space between two radially extending surfaces arranged about a shaft and axially displaceable relative to each other along the shaft includes a first sleeve-shaped seal part and an elastically resilient sealing body. The first sleeve-shaped part forms together with the shaft an axially open space facing the cooperating surface. The elastically, resilient sealing body has in an uncompressed state a cross-sectional area and/or a shape deviating from the area and/or shape of the axially open space. The sealing body when subjected to axial forces causing the sealing body surface and the cooperating surface to abut each other is compressed sealingly between the axial space and the cooperating surface, thereby creating a sealing engagement against the entrance of the slit-shaped space and against the shaft.

Description:
This application is based on and claims priority under 35 U.S.C. § 119 with respect to Swedish Patent Application No. 9804613-9 filed on Dec. 30, 1998, the entire content of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention generally relates to a sealing device. More particularly, the present invention pertains to a sealing device for sealing off a slit-formed space between two radially extending surfaces arranged around a shaft and axially displaceable relative to each other along the shaft. 
     BACKGROUND OF THE INVENTION 
     Sealing devices for sealing off a slit-formed space between two radially extending surfaces arranged on a shaft are known in a plurality of different designs. These earlier designs have been rather complex and/or have required a certain skill at mounting the sealing device in a manner appropriate for giving the best possible sealing effect. 
     A need thus exists for a sealing device of this type which is simple in design and to relatively easy install, and yet which is very efficient. 
     SUMMARY OF THE INVENTION 
     In light of the foregoing, one aspect of the present invention relates to a sealing arrangement that includes a shaft and two radially extending surfaces arranged about the shaft in an axially displaceable manner relative to each other along the shaft, a first sleeve-shaped seal part and a sealing body. The first sleeve-shaped seal part extends around the shaft and forms together with the shaft a space facing one of the radially extending surfaces. The resilient sealing body is positioned in the space for being compressed from an uncompressed state to a compressed state. The cross-sectional area and/or shape of the sealing body is different from the cross-sectional area and/or shape of the axially open space when the sealing body is uncompressed. The sealing body is sealingly compressed within the axially open space and against the one radially extending surface when subjected to axial forces causing the sealing body to abut against the one radially extending surface to thereby create a sealing engagement against the one radially extending surface and against the shaft. 
     Another aspect of the invention relates to a sealing device for sealing off a slit-shaped space between two radially extending surfaces that are arranged about a shaft in an axially displaceable manner relative to each other along the shaft. The device includes a first sleeve-shaped seal part forming together with the shaft an axially open space facing one of the radially extending. The device further includes an elastically resilient sealing body having in an uncompressed state a cross-sectional area different from the cross-sectional area of the axially open space and/or a shape different from the shape of the axially open space so that the sealing body, when subjected to axial forces causing a surface of the sealing body to abut against the one radially extending surface, is compressed sealingly between the axially open space and the one radially extending surface to thereby create a sealing engagement against an entrance of the slit-shaped space and against the shaft. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     The foregoing and additional features of the present invention will become more apparent from the following detailed description considered with reference to the accompanying drawing figures in which like elements are designated by like reference numerals and wherein; 
     FIG. 1 is a side view of a portion of shaft with a sealed off bearing combination illustrating a first embodiment of the sealing device according to the present invention; 
     FIG. 2 is an enlarged side view of a portion of the shaft and sealed off bearing combination shown in FIG. 1; 
     FIG. 3 is a side view schematically illustrating a ball bearing sealed off with a second embodiment of the sealing device according to the present invention before mounting; 
     FIG. 4 is a side view schematically illustrating a ball bearing sealed off with the second embodiment of the sealing device according to the present invention after mounting; 
     FIG. 5 is a side view of a portion of a shaft with a ring member to be sealed off by a third embodiment of the sealing device according to the present invention in a pre-mounting position. 
     FIG. 6 is a plan view of a portion of a sleeve forming part of the sealing device illustrated in FIG. 5; 
     FIG. 7 is a plan view of a sealing body to be used with the sleeve shown in FIG. 6; and 
     FIG. 8 is a side view of a portion of a shaft with a ring member corresponding to FIG. 5, but with the sealing device is shown in a mounted condition. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates a bearing arrangement particularly adapted for supporting a shaft, for example a shaft in a motor pump. The bearing arrangement incorporates a taper roller bearing I mounted on the shaft  2 , only a small portion of which is illustrated, a deep groove ball bearing  3  mounted on the same shaft  2 , and a two part sealing device  4 ,  5 , provided between the two bearings. The two part sealing device  4 ,  5  is adapted to seal off the left hand side of the ball bearing  3 , the space between the shaft  2  and the interior of the taper roller bearing  1 , and particularly the slit-formed space between the side face of the taper bearing inner race ring  1   a , extending radially away from the shaft, and the radial surface  4   d  on the sealing device as shown in FIG.  2 . 
     As can be better seen in FIG. 2 which illustrates the two-part sealing device  4 ,  5  on a larger scale, the sealing device includes a first part  4  and a second part  5 . The first part  4  is constituted by a substantially cylindrical sleeve  4   a  adapted to fit around the shaft  2 , a substantially radially extending portion  4   a  provided at one axial end of the cylindrical sleeve  4   a , and an axially extending flange portion  4   c  continuing from the radially extending portion  4   a . The radial portion  4   a  and the axial flange  4   c  form with the shaft  2  an axially open, annular space  6  as shown in FIG.  1 . The axially extending flange  4   c  terminates in the radial sealing surface  4   d  arranged to abut against the side face of the inner race ring of the taper roller bearing  1 , thereby forming together with the side face of the taper bearing inner race ring a slit-shaped space. 
     A resiliently compressible sealing body  7  is provided in the annular space  6 . The resiliently compressible sealing body  7  possesses a size and/or a shape which guarantees that it is compressed when the abutting sealing surface  4   d  is pressed into abutment with the cooperating radial surface, here the side surface of the inner taper bearing race ring. The compressed sealing body  7  sealingly contacts the entrance of the slit-shaped space and also the shaft  2 , thereby under a certain pretension, preventing leakage in any direction along the shaft  2  at this annular space  6  and also through the slit-shaped space. In the embodiment shown, the sealing body  7  is provided with a projecting rim portion or projecting element  7   a  that is adapted to increase the contact pressure between the compressed sealing body  7  and the cooperating surface directly against the side face of the bearing ring, or in an annular groove provided in the side face of the taper bearing inner race ring. 
     In the embodiment shown in FIGS. 1 and 2, the axial end of the sleeve-formed part  4   a  of the first seal part  4  that is located opposite to the axial end at which is located the radially extending part  4   b  is provided with an external, annular chamfer  8 . This annular chamfer  8  is adapted to engage the inner race ring of the ball bearing  3 , and thereby the rounded side face of the bearing ring, thereby giving a sealing line contact against this portion of the bearing ring as shown in FIG.  1 . 
     The second part  5  of the sealing device includes a first shield member  5   a  made from metal or a plastic material. The first shield member  5   a  is cup-shaped with a central opening. The diameter of the opening in the shield member  5   a  is somewhat bigger than the outer diameter of the sleeve-formed first seal part  4 . One axial side of the shield member  5   a  is provided with an elastic and resilient lining  9 . The elastic and resilient lining  9  has two inwardly projecting and axially spaced apart sealing lips  9   a ,  9   b , both arranged to slidingly contact the external peripheral surface of the first seal part  4 . With respect to the axial direction, the two sealing lips  9   a ,  9   b  are positioned on opposite sides of the radially extending adjacent portion of the first shield member  5   a  as seen in FIG. 2. A spring  9   c  encircles the axially extending portion of the lining  9  to urge the sealing lip  9   b  against the cooperating peripheral surface of the first seal part  4 , thereby improving the sealing effect. The lining  9  is preferably affixed to the shield member  5   a  by vulcanization or in any other convenient manner. 
     FIGS. 3 and 4 illustrate in partial cross-sectional views a second embodiment of the invention. The drawing figures illustrate a portion of a ball bearing  10  having an inner ring, an outer ring, and a number of balls provided between the bearing rings and in rolling contact with the grooved race tracks formed in the rings. The balls are guided and kept apart by a cage. On the left hand side as seen in the drawing figures, a conventional sliding seal is provided to span the space between the inner and outer bearing rings. 
     A seal according to the present invention is provided at the right hand side as seen in FIGS. 3 and 4. This seal incorporates a sleeve member  11  having a substantially cylindrical portion  11   a , a substantially radially extending portion  11   b , and a substantially axially extending flange portion  11   c . The cylindrical portion  11   a  is adapted to fit around the shaft (not shown). The radially extending portion  11   b  extends from one end of the cylindrical portion  11   a  and forms a continuation of the cylindrical portion  11   a , while the axially extending flange portion  11   c  extends from and forms a continuation of the radially extending portion  11   b . The radially extending portion  11   b  and the axially extending flange portion  11   c  form together with the shaft an axially open, annular space. The axially extending flange  11   c  ends in a radial sealing surface  11   d  arranged to abut against the side face of the inner race ring of the bearing  10 . The radial sealing surface  11   d  of the axially extending flange  11   c  forms together with the side face of the bearing inner race ring a slit-shaped space. A resiliently compressible sealing body  12  is positioned in this annular space. The resiliently compressible sealing body  12  possesses a size and/or a shape which guarantees that the sealing body  12 , when the abutting sealing surface  11   d  is pressed into abutment with the cooperating radial side surface of the inner bearing ring is compressed so that it sealingly contacts the entrance of the slit-shaped space and also the shaft, thereby, under a certain pretension, preventing leakage in any direction along the shaft at this annular space and also through the slit-shaped space. A lip seal  13  of any appropriate type is arranged to cooperate with the sleeve member to thereby form an additional seal. In the embodiment shown, the lip seal  13  cooperates with the outer peripheral surface of the axial flange  11   c.    
     FIG. 3 shows the situation before mounting of the seal  11 , whereas FIG. 4 shows the bearing  10  with the seal  11  mounted thereto. Thus in FIG. 3, the bearing  10  is situated on a shaft in its mounting position. Also the seal  11  is positioned on the shaft, but with its radial side face  11   d  facing the bearing at a small axial distance from the side face of the inner bearing ring. As can be seen from FIG. 3, the compressible, resilient sealing body  12  possesses a size and configuration by which it clearly projects outside the side face  11   d  of the seal. As shown in FIG. 4, the seal  11  has been pushed up in a direction to the left in the drawing figure so that the radial side face  11   d  of the seal  11  is positioned to abut the side face of the bearing inner ring. The sealing body  12  has thus been compressed in its space and is pressing sealingly against the side face of the bearing inner ring and also against the shaft in the manner depicted by the arrow in FIG.  4 . 
     To increase the ability of the sealing body  12  to adapt itself to the shape of the shaft, the surface of the sealing body facing the shaft can be serrated to provide a serrated surface  12   a  in FIG.  3 . 
     The bearing  10  is preferably provided with a volume or amount of lubricant  14 . When the bearing is sealed off in the illustrated manner it is able to contain a sufficient lubricant volume or amount for its operating life. For maintaining the axial force required to cause the sealing body to be sufficiently compressed for sealing off the spaces, the sleeve member  11  is arrested in the position illustrated in FIG. 4 by way of a proper locking device which are known per se, such as a locking ring or the like. 
     FIGS. 5-8 illustrate a further form of the sealing device according to the present invention. FIG. 5 schematically illustrates a portion of a shaft  15  on which is arranged a ring  16 , for example a bearing ring, having a side face surface  16   a  projecting or extending radially outwardly relative to the shaft. A sealing device according to the present invention is positioned to the left of the ring member  16 . The sealing device according to the present invention includes a sleeve member  17  defined by a substantially cylindrical sleeve portion  17   a , a sloping portion  17   b  and an axially extending flange portion  17   c . The sleeve portion  17   a  is adapted to fit around the shaft  15 . The sloping portion  17   b  extends from and forms a continuation of one axial end of the sleeve portion  17   a  in an upwardly and outwardly sloping manner. The sloping portion  17   b  continues into the flange portion  17   c  which extends substantially axially. The sloping portion  17   b  and the flange portion  17   c  form together with the shaft  15  an axially open, annular space. The axially extending flange  17   c  ends in a radial sealing surface  17   d  that is positioned to abut against the side face of the ring  16 , thereby forming together with the side face of the ring  16  a slit-shaped space. 
     A resiliently compressible sealing body  18  is located in this annular space. The sealing body  18  in this embodiment is formed as an O-ring seal. The resiliently compressible sealing body  18  has a shape which guarantees that the sealing body  18 , when the abutting sealing surface  17   d  is pressed into abutment with the cooperating radial surface defined by the side face  16   a  of the ring, is compressed. This compression of the sealing body  18  causes the sealing body  18  to sealingly contact the entrance of the slit-shaped space and also the shaft, thereby, under a certain pretension, preventing leakage in any direction along the shaft at this annular space and also through the slit-shaped space. In this embodiment, the axially open space formed between the sloping portion  17   b  of the seal  17 , the axial flange  17   c  of the seal  17 , the shaft  15  and the cooperating radial side face  16   a  of the ring  16 , has a cross-sectional area greater than the cross-sectional area of the sealing body  18 . In spite of this difference in area, the difference in shape between the annular space and the sealing body  18  means that the sealing body  18  will still be compressed into abutment against the radially extending surface of the ring member  16  and against the shaft  15  when the sleeve  17  is pushed up on the shaft  15  to a position where its radial surface  17   d  abuts against the side face  16   a  of the ring  16  (or vice versa). This is illustrated in FIG.  8 . FIG. 8 also illustrates how a conventional lip seal  19  can be provided to cooperate with the outer peripheral surface of the sleeve  17   a , and how the sleeve member  17  can be arrested in its mounted position by way of a locking ring  20  of an appropriate type. 
     In the embodiments of the sealing device according to the present invention shown in FIGS. 1 and 2, and in FIGS. 3 and 4, it is convenient to arrange the sealing body  7 ,  12  to be fixedly connected to the sleeve member  4 ,  11 . This can be achieved by, for example, gluing, vulcanization or the like. This facilitates the handling of the seal because the two parts of the seal need not be handled, stored and transported separately, but rather as complete sealing units. It is thus possible to ascertain that the sealing body is always in position when the seal is to be mounted. 
     With the embodiment of the sealing device according to the present invention illustrated in FIGS. 5-8, this problem is solved in a different manner in that the sleeve member  17  and its axial flange member  17   c  is provided with at least two axially outwardly opening grooves  21 , preferably diametrically opposed or symmetrically disposed around the sleeve as illustrated in FIGS. 5 and 6. These grooves  21  are adapted to receive projecting lugs  22  arranged on the sealing body  18  which are shown in FIG.  7 . 
     In accordance with the present invention, the cross-sectional area and/or shape of the sealing body is different from the cross-sectional area and/or shape of the axially open space when the sealing body is uncompressed. As illustrated in various drawing figures, the sealing body possesses a dimension with respect to at least an axial dimension of the sleeve-shaped part that exceeds that of the axially open space. 
     The present invention thus provides a sealing device for sealing off in a rather effective manner a slit-formed space between two radially extending surfaces arranged on a shaft. The sealing device is relatively simple in construction and does not require a significant amount of skill in mounting the sealing device. 
     The principles, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.