Abstract:
To improve sealing performance by a labyrinth to inhibit entry of dust, a sealing device ( 1 ) comprising an inner peripheral side sealing member ( 2 ) fitted to an inner peripheral side mounting member and an outer peripheral side sealing member ( 3 ) fitted to the outer peripheral side mounting member, both relatively rotating, has an outer peripheral tube part ( 4   c ) formed on the outer peripheral portion of the metal ring ( 4 ) of the inner peripheral side sealing member ( 2 ), and a series of long labyrinth spaces ( 8, 9, 10 ) is formed between the outer peripheral surface of the outer peripheral tube part ( 4   c ) and the outer peripheral side sealing member ( 3 ), between the end face of the outer peripheral tube part ( 4   c ) and the outer peripheral side sealing member ( 3 ), and between the inner peripheral surface of the outer peripheral tube part ( 4   c ) and the outer peripheral side sealing member ( 3 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a national stage of the International Application No. PCT/JP2006/310296 filed May 24, 2006 and published in Japanese. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a sealing device in accordance with a sealing technique. The sealing device in accordance with the present invention is used, for example, as a hub bearing seal in an automotive associated field, or used in a general purpose machine or the like. 
         [0004]    2. Description of the Conventional Art 
         [0005]    In conventional, there has been known a sealing device  51  as shown in  FIG. 5 , and the sealing device  51  is structured by a combination of a slinger member  52  attached to an inner peripheral side attaching member (for example, an inner ring)  61  corresponding to one of relatively rotating two members (for example, inner and outer rings of a bearing)  61  and  62 , and a lip seal member  53  attached to an outer peripheral side attaching member (for example, the outer ring)  62  corresponding to the other. 
         [0006]    The slinger member  52  is made of a metal material, is formed in an approximately L-shape in cross section by integrally forming an annular radially rising part  52   b  at one end in an axial direction of a tubular part  52   a,  and is fitly attached to an outer peripheral surface of the inner peripheral side attaching member (for example, the inner ring)  61  by the tubular part  52   a.  The lip seal member  53  is structured such that a plurality of seal lips  55  (three lips in the drawing) made of a rubber-like elastic material are attached to a metal ring  54 , which also has an approximately L-shaped cross section, and is fitly attached to an inner peripheral surface of the outer peripheral side attaching member (for example, the outer ring)  62  by the metal ring  54 . 
         [0007]    Further, a peripheral end (an upper end in the drawing) of the radially rising part  52   b  in the slinger member  52  faces to the lip seal member  53  via a slight radial gap c, whereby here is provided with a labyrinth seal  56  for inhibiting dust, muddy water or the like in an outer portion A from making intrusion into an inner portion B of the sealing device  51 . 
         [0008]    Since the sealing device  51  having the structure mentioned above is provided with the labyrinth seal  56  inhibiting dust, muddy water or the like from making intrusion between the peripheral end of the radially rising part  52   b  of the slinger member  52  and the lip seal member  53  facing thereto as mentioned above, it is possible to achieve a certain degree of dust resistance on the basis of a seal effect obtained by the labyrinth seal  56 . However, since an axial length of the labyrinth seal  56  is significantly short, there is a disadvantage that its sealing performance is not so high. 
         [0009]    Further, in conventional, as shown in  FIG. 6 , there has been developed a technique of setting the axial length of the labyrinth seal  56  larger by integrally forming an outer peripheral tube part  52   c  at an outer peripheral position of the slinger member  52  so as to set a labyrinth space along an overall length of an outer peripheral surface of the outer peripheral tube part  52   c.  However, since even such the length remains to be insufficient, the sealing performance of the labyrinth seal  56  is yet insufficient (Japanese Unexamined Utility Model Publication No. 3-59562). 
       SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
       [0010]    The present invention is made by taking the points mentioned above into consideration, and an object of the present invention is to provide a sealing device in which a sealing performance obtained by a labyrinth seal is further improved in comparison with the conventional art mentioned above, to thereby make it possible to extremely effectively inhibit dust, muddy water or the like from making intrusion. 
       Means for Solving the Problem 
       [0011]    In order to achieve the object mentioned above, in accordance with a first aspect of the present invention, there is provided a sealing device structured by a combination of an inner peripheral side sealing member attached to an inner peripheral side attaching member corresponding to one of two relatively rotating members, and an outer peripheral side sealing member attached to an outer peripheral side attaching member corresponding to the other of the two members, in which the inner peripheral side sealing member has a metal ring fixed to the inner peripheral side attaching member, and the outer peripheral side sealing member has a metal ring fixed to the outer peripheral side attaching member, and seal lips made of a rubber-like elastic material and attached to the latter metal ring so as to be slidably brought into close contact with the metal ring of the inner peripheral side sealing member, wherein an outer peripheral tube part is provided at an outer peripheral portion of in the metal ring in the inner peripheral side sealing member, and a series of labyrinth spaces is provided between an outer peripheral surface of the outer peripheral tube part and the outer peripheral side sealing member, between a distal end surface of the outer peripheral tube part and the outer peripheral side sealing member and between an inner peripheral surface of the outer peripheral tube part and the outer peripheral side sealing member. 
         [0012]    Further, in accordance with a second aspect of the present invention, there is provided a sealing device structured by a combination of an inner peripheral side sealing member attached to an inner peripheral side attaching member corresponding to one of two relatively rotating members, and an outer peripheral side sealing member attached to an outer peripheral side attaching member corresponding to the other of the two members, in which the inner peripheral side sealing member has a metal ring fixed to the inner peripheral side attaching member, and the outer peripheral side sealing member has a metal ring fixed to the outer peripheral side attaching member, and seal lips made of a rubber-like elastic material and attached to the latter metal ring so as to be slidably brought into close contact with the metal ring of the inner peripheral side sealing member, wherein an outer peripheral tube part is provided at an outer peripheral portion of the metal ring in the inner peripheral side sealing member, an inclined surface expanding gradually in diameter from a distal end portion toward a proximal end portion is provided at an outer peripheral surface of the outer peripheral tube part, a corresponding inclined surface is provided at the outer peripheral side sealing member, and a labyrinth space is provided by the inclined surfaces. 
         [0013]    Further, in accordance with a third aspect of the present invention, there is provided a sealing device structured by a combination of an outer peripheral side sealing member attached to an outer peripheral side attaching member corresponding to one of two relatively rotating members, and an inner peripheral side sealing member attached to an inner peripheral side attaching member corresponding to the other of the two members, in which the outer peripheral side sealing member is constituted by a metal ring fixed to the outer peripheral side attaching member, and the inner peripheral side sealing member has a metal ring fixed to the inner peripheral side attaching member, and seal lips made of a rubber-like elastic material and attached to the latter metal ring so as to be slidably brought into close contact with the metal ring of the outer peripheral side sealing member, wherein an inner peripheral tube part is provided at an inner peripheral portion of the metal ring in the outer peripheral side sealing member, the inner peripheral tube part is in non-contact with the inner peripheral side sealing member, and a labyrinth spaces are provided between the inner peripheral tube part and the inner peripheral side sealing member. 
         [0014]    Further, in accordance with a fourth aspect of the present invention, there is provided a sealing device as recited in the third aspect, wherein labyrinth spaces are provided in series between an outer peripheral surface of the inner peripheral tube part and the inner peripheral side sealing member, between a distal end surface of the inner peripheral tube part and the inner peripheral side sealing member and between an inner peripheral surface of the inner peripheral tube part and the inner peripheral side sealing member. 
         [0015]    In the sealing device in accordance with the first aspect of the present invention provided with the structure mentioned above, since the labyrinth space is provided at each of the distal end side and the inner peripheral side, in addition to the outer peripheral side of the outer peripheral tube part provided on the metal ring of the inner peripheral side sealing member, it is possible to set a length of the labyrinth seal obtained by the labyrinth spaces longer than the conventional structure. 
         [0016]    Further, in the sealing device in accordance with the second aspect of the present invention provided with the structure mentioned above, since the labyrinth space set at the outer peripheral side of the outer peripheral tube part is not formed in an axially straight shaped, but is formed in the inclined surface shape (a taper shape or a conical surface shape), it is possible to achieve a seal function (a muddy water push-back operation) on the basis of an operation of centrifugal force at a time when the sealing device is rotated. 
         [0017]    Further, in the sealing device in accordance with the third aspect of the present invention provided with the structure mentioned above, since the inner peripheral tube part is provided at the inner peripheral portion of the metal ring in the outer peripheral side sealing member, the inner peripheral tube part is in non-contact with the inner peripheral side sealing member and the labyrinth space is provided between the inner peripheral tube part and the inner peripheral side sealing member, the non-contact type labyrinth seal obtained by the labyrinth space is arranged at a back side of the contact type lip seal obtained by the seal lip, whereby it is possible to reduce a seal load borne by the labyrinth seal. (Since the lip seal is arranged at a front side and the labyrinth seal is arranged at a back side thereof, as seen from the side of dust, muddy water or the like in the outer portion of the sealing device, the lip seal serves as a primary seal, and the labyrinth seal serves as a secondary seal. Accordingly, since the labyrinth seal corresponding to the secondary seal is to seal only the dust leaking from the lip seal corresponding to the primary seal, it is considered that the labyrinth seal can sufficiently seal such a small amount of dust). 
         [0018]    Further, as described in the fourth aspect of the present invention, in the case that the labyrinth spaces are provided in series between the outer peripheral surface of the inner peripheral tube part and the inner peripheral side sealing member, between the distal end surface of the inner peripheral tube part and the inner peripheral side sealing member and between the inner peripheral surface of the inner peripheral tube part and the inner peripheral side sealing member, it is possible to set the length of the labyrinth seal longer than the case that the labyrinth seal is provided only between the inner peripheral surface of the inner peripheral tube part and the inner peripheral side sealing member. Since the sealing performance of the labyrinth seal can be increased in correspondence to its length, it is possible to increase the sealing performance. 
       EFFECT OF THE INVENTION 
       [0019]    The present invention has the following effect. 
         [0020]    In the sealing device in accordance with the first aspect of the present invention, since a series of the labyrinth spaces is provided between the outer peripheral surface of the outer peripheral tube part provided on the metal ring of the inner peripheral side sealing member and the outer peripheral side sealing member, between the distal end surface of the outer peripheral tube part and the outer peripheral side sealing member and between the inner peripheral surface of the outer peripheral tube part and the outer peripheral side sealing member, the length of the labyrinth seal obtained by a plurality of the labyrinth spaces is set longer than the conventional structure. Accordingly, it is possible to further improve the sealing performance obtained by the labyrinth, and it is possible to effectively inhibit dust, muddy water or the like from making intrusion. 
         [0021]    Further, in the sealing device in accordance with the second aspect of the present invention, since the inclined surface expanding gradually in diameter from the distal end portion toward the proximal end portion is provided at the outer peripheral tube part provided on the metal ring of the inner peripheral side sealing member, the corresponding inclined surface is provided at the outer peripheral side sealing member, and the inclined surface shaped labyrinth space is provided by both the inclined surfaces, the inclined surface shaped labyrinth space achieves the sealing effect by utilizing of centrifugal force in addition to the labyrinth seal effect. Accordingly, it is possible to further improve the sealing performance obtained by the labyrinth, and it is possible to effectively inhibit dust, muddy water or the like from making intrusion. 
         [0022]    Further, in the sealing device in accordance with the third aspect of the present invention, since the inner peripheral tube part is provided at the inner peripheral portion of the metal ring in the outer peripheral side sealing member, the inner peripheral tube part is in non-contact with the inner peripheral side sealing member, and the labyrinth spaces are provided between the inner peripheral tube part and the inner peripheral side sealing member, the non-contact type labyrinth seal obtained by the labyrinth spaces is arranged at the back side of the contact type lip seal obtained by the seal lip, whereby it is possible to reduce the seal load borne by the labyrinth seal. Accordingly, in the relationship between the sealing performance of the labyrinth seal and the amount of an object to be sealed, the former sealing performance is relatively increased, whereby it is possible to further improve the sealing performance obtained by the labyrinth, and it is possible to effectively inhibit dust, muddy water or the like from making intrusion. 
         [0023]    Further, in the sealing device in accordance with the fourth aspect of the present invention, since the labyrinth spaces are provided in series between the outer peripheral surface of the inner peripheral tube part and the inner peripheral side sealing member, between the distal end surface of the inner peripheral tube part and the inner peripheral side sealing member and between the inner peripheral surface of the inner peripheral tube part and the inner peripheral side sealing member, it is possible to set the length of the labyrinth seal longer, whereby it is possible to further improve the sealing performance. 
     
    
     
       BRIEF EXPLANATION OF DRAWINGS 
         [0024]      FIG. 1  is a cross sectional view of a main portion of a sealing device in accordance with a first embodiment of the present invention; 
           [0025]      FIG. 2  is a cross sectional view of a main portion of a sealing device in accordance with a second embodiment of the present invention; 
           [0026]      FIG. 3  is a cross sectional view of a main portion of a sealing device in accordance with a third embodiment of the present invention; 
           [0027]      FIG. 4  is a cross sectional view of a main portion of a sealing device in accordance with a fourth embodiment of the present invention; 
           [0028]      FIG. 5  is a cross sectional view showing an installed state of a sealing device in accordance with a conventional art; and 
           [0029]      FIG. 6  is a cross sectional view of a main portion of a sealing device in accordance with another conventional art. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0030]    A description will be next given of embodiments in accordance with the present invention with reference to the accompanying drawings. 
       First Embodiment 
       [0031]      FIG. 1  shows a cross section of a main portion of a sealing device  1  in accordance with a first embodiment of the present invention. The sealing device  1  in accordance with the embodiment is used as a seal for a hub bearing (a hub seal) in an automotive associated field, and is structured as follows. In this case, the embodiment corresponds to an embodiment on the invention in accordance with the first aspect of the present invention. 
         [0032]    First, the sealing device  1  has an inner peripheral side sealing member  2  attached to a bearing inner ring (an inner peripheral side attaching member (not shown)) corresponding to one member of two relatively rotating members and rotating together with the bearing inner ring, and an outer peripheral side sealing member  3  attached to a bearing outer ring (an outer peripheral side attaching member (not shown)) corresponding to the other member of the two members and not rotating. 
         [0033]    The inner peripheral side sealing member  2  is structured by a slinger member (hereinafter, referred to simply as a slinger)  4  corresponding to one kind of metal ring. 
         [0034]    The slinger  4  is made of a metal material such as a sheet metal or the like, and is structured such that an annular radially rising part (a flat surface part)  4   b  is integrally formed on an end portion at one side (a right side in the drawing) in an axial direction of a tubular part  4   a  so as to extend outward in a radial direction (upward in the drawing), and is fitly attached to an outer peripheral surface of a bearing inner ring by the former tubular part  4   a.    
         [0035]    On the other hand, the outer peripheral side sealing member  3  is structured by a lip seal member (hereinafter, referred to simply as a lip seal)  5 , and the lip seal  5  is structured by a combination of a metal ring  6 , and a rubber-like elastic body  7  attached (adhered in a vulcanizing manner) to the metal ring  6 . 
         [0036]    The metal ring  6  is made of a metal material such as a sheet metal or the like, is obtained by integrally forming an annular radially rising part (a flat surface part)  6   b  on an end portion at the other side (a left side of the drawing) in an axial direction of the tubular part  6   a  so as to extend inward in a radial direction (downward in the drawing), and is fitly attached to an inner peripheral surface of a bearing outer ring by the former tubular part  6   a.    
         [0037]    The rubber-like elastic body  7  integrally has an outer peripheral rubber part  7   a  attached to a distal end outer peripheral surface of the tubular part  6   a  of the metal ring  6 , a distal end rubber part  7   b  attached to a distal end surface of the tubular part  6   a,  an inner peripheral rubber part  7   c  attached to an inner peripheral surface of the tubular part  6   a,  an end surface rubber part  7   d  attached to an inner side end surface of the radially rising part  6   b  of the metal ring  6 , a seal lip (a side lip)  7   e  supported by the end surface rubber part  7   d  and slidably brought into close contact with an inner side end surface of the radially rising part  4   b  of the slinger  4 , and a seal lip (a radial lip)  7   f  supported by the end surface rubber part  7   d  in the same manner and slidably brought into close contact with an outer peripheral surface of the attaching part  4   a  of the slinger  4 . 
         [0038]    Further, an outer peripheral tube part  4   c  is integrally formed on a distal end of the radially rising part  4   b  corresponding to an outermost peripheral portion of the slinger  4  so as to extend toward the other side in the axial direction, whereby the slinger  4  is formed in an approximately C-shaped cross section as a whole. 
         [0039]    Further, an annular protruding part  7   g  is integrally formed on the end surface rubber part  7   d  of the rubber-like elastic body  7  in the lip seal  5  so as to extend toward one side in an axial direction in such a manner as to be positioned at an inner peripheral side of the outer peripheral tube part  4   c,  and the protruding part  7   g  has a tubular outer peripheral surface  7   h.    
         [0040]    Therefore, in accordance with the structure mentioned above, since labyrinth spaces  8 ,  9  and  10  each having a small gap are formed between the outer peripheral surface of the outer peripheral tube part  4   c  and the inner peripheral surface of the inner peripheral rubber part  7   c,  between the distal end surface of the outer peripheral tube part  4   c  and the inner side end surface of the end surface rubber part  7   d  and between the inner peripheral surface of the outer peripheral tube part  4   c  and the outer peripheral surface  7   h  of the protruding part  7   g,  and these labyrinth spaces  8 ,  9  and  10  at three positions are formed in an approximately C-shaped cross section and are structured in such a manner as to be sequential in series, an overall length of a labyrinth seal  11  obtained by the labyrinth spaces  8 ,  9  and  10  is set longer than the conventional structure. Accordingly, since the overall length of the labyrinth seal  11  is set longer than the conventional structure as mentioned above, it is possible to further improve a sealing performance generated by the labyrinth seal  11 , and it is possible to effectively inhibit dust, muddy water, or the like from making intrusion into the sealing device  1 , and into the bearing too. 
       Second Embodiment 
       [0041]      FIG. 2  shows a cross section of a main portion of a sealing device  1  in accordance with a second embodiment of the present invention. The sealing device  1  in accordance with the embodiment is used as a seal for a hub bearing (a hub seal) in an automotive associated field, and is structured as follows. In this case, the embodiment corresponds to an embodiment on the invention in accordance with the second aspect of the present invention. 
         [0042]    First, the sealing device  1  has an inner peripheral side sealing member  2  attached to a bearing inner ring (an inner peripheral side attaching member (not shown)) corresponding to one member of two relatively rotating members and rotating together with the bearing inner ring, and an outer peripheral side sealing member  3  attached to a bearing outer ring (an outer peripheral side attaching member (not shown)) corresponding to the other member of the two members and not rotating. 
         [0043]    The inner peripheral side sealing member  2  is structured by a slinger member (hereinafter, referred to simply as a slinger)  4  corresponding to one kind of metal ring. 
         [0044]    The slinger  4  is made of a metal material such as a sheet metal or the like, and is structured such that an annular radially rising part (a flat surface part)  4   b  is integrally formed on an end portion at one side (a right side in the drawing) in an axial direction of a tubular part  4   a  so as to extend outward in a radial direction (upward in the drawing), and is fitly attached to an outer peripheral surface of a bearing inner ring by the former tubular part  4   a.    
         [0045]    On the other hand, the outer peripheral side sealing member  3  is structured by a lip seal member (hereinafter, referred to simply as a lip seal)  5 , and the lip seal  5  is structured by a combination of a metal ring  6 , and a rubber-like elastic body  7  attached (adhered in a vulcanizing manner) to the metal ring  6 . 
         [0046]    The metal ring  6  is made of a metal material such as a sheet metal or the like, is obtained by integrally forming an annular radially rising part (a flat surface part)  6   b  on an end portion at the other side (a left side of the drawing) in an axial direction of the tubular part  6   a  so as to extend inward in a radial direction (downward in the drawing), and is fitly attached to an inner peripheral surface of a bearing outer ring by the former tubular part  6   a.    
         [0047]    The rubber-like elastic body  7  integrally has an outer peripheral rubber part  7   a  attached to a distal end outer peripheral surface of the tubular part  6   a  of the metal ring  6 , a distal end rubber part  7   b  attached to a distal end surface of the tubular part  6   a,  an inner peripheral rubber part  7   c  attached to an inner peripheral surface of the tubular part  6   a,  an end surface rubber part  7   d  attached to an inner side end surface of the radially rising part  6   b  of the metal ring  6 , a seal lip (a side lip)  7   e  supported by the end surface rubber part  7   d  and slidably brought into close contact with an inner side end surface of the radially rising part  4   b  of the slinger  4 , and a seal lip (a radial lip)  7   f  supported by the end surface rubber part  7   d  in the same manner and slidably brought into close contact with an outer peripheral surface of the attaching part  4   a  of the slinger  4 . 
         [0048]    Further, an outer peripheral tube part  4   c  is integrally formed on a distal end of the radially rising part  4   b  corresponding to an outermost peripheral portion of the slinger  4  so as to extend toward the other side in the axial direction. In this embodiment, particularly, the outer peripheral tube part  4   c  is formed in an inclined surface shape (a taper surface shape or a conical surface shape) expanding gradually in diameter from a distal end portion toward a proximal end portion. The expanding direction is a direction expanding from the other side in an axial direction (a left side of the drawing) to one side (a right side of the drawing). Further, in conformity with this, an inner peripheral surface  7   i  of the inner peripheral rubber part  7   c  of the rubber-like elastic body  7  in the lip seal member  5  is also formed in an inclined surface shape expanding gradually in diameter from the other side in the axial direction toward one side. Accordingly, an inclined surface shaped labyrinth space  12  expanding gradually in diameter from the other side in the axial direction toward one side is formed between the outer peripheral surface  4   d  of the outer peripheral tube part  4   c  and the inner peripheral surface  7   i  of the inner peripheral rubber part  7   c,  whereby a labyrinth seal  11  is structured. The inclined surface shaped labyrinth space  12  is structured, for example, such that its length can be set longer in comparison with the axially straight shaped labyrinth space  8  shown in the first embodiment mentioned above. 
         [0049]    In the sealing device  1  having the structure mentioned above, when the slinger  4  at the rotating side is rotated at a high speed together with the bearing inner ring, a muddy water push-back function caused by an operation of centrifugal force is achieved within the inclined surface shaped labyrinth space  12 . The muddy water making intrusion into the labyrinth space  12  is pushed back in an outward direction (a direction of an arrow) on the basis of the push-back function. Accordingly, since the muddy water push-back effect on the basis of the centrifugal force is achieved in addition to the labyrinth seal effect generated by the labyrinth space  12  mentioned above, it is possible to improve a sealing capacity of the sealing device  1  as the whole, whereby it is possible to effectively inhibit dust, muddy water or the like from making intrusion into the sealing device  1  and into the bearing too. 
         [0050]    In this case, a cross sectional shape of the inclined surface shaped labyrinth space  12  may be formed in a circular arc shape in addition to the inclined straight shape as illustrated. 
         [0051]    Further, a projection or a groove may be provided in the outer peripheral tube part  4   c  or/and the inner peripheral surface  7   i  of the inner peripheral rubber part  7   c.  As for a shape of the projection or the groove, it is possible to improve a shaking off effect by employing a shape which is parallel to the axial direction, and it is possible to expect a seal effect on the basis of a pumping operation by employing an inclined shape with respect to the axial direction, or a thread shape by forming a spiral shape. 
       Third Embodiment 
       [0052]      FIG. 3  shows a cross section of a main portion of a sealing device  21  in accordance with a third embodiment of the present invention. The sealing device  21  in accordance with the embodiment is used as a seal for a hub bearing (a hub seal) in an automotive associated field, and is structured as follows. In this case, the embodiment corresponds to an embodiment on the invention in accordance with the third aspect of the present invention. 
         [0053]    First, the sealing device  21  has an outer peripheral side sealing member  22  attached to a bearing outer ring (an outer peripheral side attaching member (not shown)) corresponding to one member of two relatively rotating members and not rotating, and an inner peripheral side sealing member  23  attached to a bearing inner ring (an inner peripheral side attaching member (not shown)) corresponding to the other member of the two members and rotating together with the bearing inner ring. 
         [0054]    The outer peripheral side sealing member  22  is structured by a single unit of a metal ring  24 , and the metal ring  24  is made of a metal material such as a sheet metal or the like, and is structured such that an annular radially rising part (a flat surface part)  24   b  is integrally formed on an end portion at one side (a left side in the drawing) in an axial direction of a tubular part  24   a  so as to extend inward in a radial direction (downward in the drawing), and is fitly attached to an inner peripheral surface of a bearing outer ring by the former tubular part  24   a.    
         [0055]    On the other hand, the inner peripheral side sealing member  23  is structured by a lip seal member (hereinafter, referred to simply as a lip seal)  25 , and the lip seal  25  is structured by a combination of a metal ring  26 , and a rubber-like elastic body  27  attached (adhered in a vulcanizing manner) to the metal ring  26 . 
         [0056]    The metal ring  26  is made of a metal material such as a sheet metal or the like, is obtained by integrally forming an annular radially rising part (a flat surface part)  26   b  on an end portion at the other side (a right side of the drawing) in an axial direction of the tubular part  26   a  so as to extend outward in a radial direction (upward in the drawing), and is fitly attached to an outer peripheral surface of a bearing inner ring by the former tubular part  26   a.    
         [0057]    The rubber-like elastic body  27  integrally has an inner peripheral rubber part  27   a  attached to a distal end inner peripheral surface of the tubular part  26   a  of the metal ring  26 , a distal end rubber part  27   b  attached to a distal end surface of the tubular part  26   a,  an outer peripheral rubber part  27   c  attached to an outer peripheral surface of the tubular part  26   a,  an end surface rubber part  27   d  attached to an inner side end surface of the radially rising part  26   b  of the metal ring  26 , a seal lip (a radial lip)  27   e  supported by the end surface rubber part  27   d  and slidably brought into close contact with an inner peripheral surface of the tubular part  24   a  of the metal ring  24  in the outer peripheral side sealing member  22 , and a seal lip (a side lip)  27   f  supported by the end surface rubber part  27   d  in the same manner and slidably brought into close contact with an inner side end surface of the radially rising part  24   b  of the metal ring  24  in the outer peripheral side sealing member  22 . 
         [0058]    Further, an inner peripheral tube part  24   c  is integrally formed on a distal end of the radially rising part  24   b  corresponding to an innermost peripheral portion of the metal ring  24  of the outer peripheral side sealing member  22  so as to extend toward one side in an axial direction, whereby the metal ring  24  is formed in an approximately C-shaped cross section as a whole. 
         [0059]    The inner peripheral tube part  24   c  is arranged close to the inner peripheral side sealing member  23  and is structured such as to be in non-contact with the inner peripheral side sealing member  23 , labyrinth spaces  28  and  29  each having a small gap are formed between a leading end surface of the inner peripheral tube part  24   c  and an inner side end surface of the end surface rubber part  27   d  and between an inner peripheral surface of the inner peripheral tube part  24   c  and an outer peripheral surface of the outer peripheral rubber part  27   c,  and the labyrinth spaces  28  and  29  at these two positions are formed in an approximately L-shaped cross section and are structured in such a manner as to be sequent in series, whereby a labyrinth seal  30  is formed in the portion. 
         [0060]    In the sealing device  21  having the structure mentioned above, since the inner peripheral tube part  24   c  is provided at the inner peripheral portion of the metal ring  24  in the outer peripheral side sealing member  22 , the inner peripheral tube part  24   c  is in non-contact with the inner peripheral side sealing member  23  and the labyrinth spaces  28  and  29  are provided between the inner peripheral tube part  24   c  and the inner peripheral side sealing member  23 , the contact type labyrinth seal  30  generated by the labyrinth spaces  28  and  29  is arranged at a back side of the non-contact type lip seal generated by the seal lips  27   e  and  27   f,  and it is possible to substantially reduce a seal load borne by the labyrinth seal  30 . Accordingly, in a relationship between a sealing performance of the labyrinth seal  30  and an amount of an object to be sealed, since the former sealing performance is relatively increased, it is possible to further improve the sealing performance by the labyrinth, and it is possible to effectively inhibit dust, muddy water or the like from making intrusion. 
         [0061]    Further, since the labyrinth spaces  28  and  29  are provided at two positions between the distal end surface of the inner peripheral tube part  24   c  and the inner side end surface of the end surface rubber part  27   d  and between the inner peripheral surface of the inner peripheral tube part  24   c  and the outer peripheral surface of the outer peripheral rubber part  27   c,  and the labyrinth spaces  28  and  29  at two positions are formed in the approximately L-shaped cross section and are structured such as to be sequent in series, an overall length of the labyrinth seal  30  generated by the labyrinth spaces  28  and  29  is set longer than the conventional structure. Accordingly, since the overall length of the labyrinth seal  30  is set longer than the conventional structure as mentioned above, it is possible to further improve the sealing performance obtained by the labyrinth seal  30 , and it is possible to effectively inhibit dust, muddy water or the like from making intrusion into the sealing device  21 , and into the bearing too. 
       Fourth Embodiment 
       [0062]      FIG. 4  shows a cross section of a main portion of a sealing device  21  in accordance with a fourth embodiment of the present invention. The sealing device  21  in accordance with the embodiment is used as a seal for a hub bearing (a hub seal) in an automotive associated field, and is structured as follows. In this case, the embodiment corresponds to an embodiment on the invention in accordance with the fourth aspect of the present invention. 
         [0063]    First, the sealing device  21  has an outer peripheral side sealing member  22  attached to a bearing outer ring (an outer peripheral side attaching member (not shown)) corresponding to one member of two relatively rotating members and not rotating, and an inner peripheral side sealing member  23  attached to a bearing inner ring (an inner peripheral side attaching member (not shown)) corresponding to the other member of the two members and rotating together with the bearing inner ring. 
         [0064]    The outer peripheral side sealing member  22  is structured by a single unit of a metal ring  24 , and the metal ring  24  is made of a metal material such as a sheet metal or the like, and is structured such that an annular radially rising part (a flat surface part)  24   b  is integrally formed on an end portion at one side (a left side in the drawing) in an axial direction of a tubular part  24   a  so as to extend inward in a radial direction (downward in the drawing), and is fitly attached to an inner peripheral surface of a bearing outer ring by the former tubular part  24   a.    
         [0065]    On the other hand, the inner peripheral side sealing member  23  is structured by a lip seal member (hereinafter, referred to simply as a lip seal)  25 , and the lip seal  25  is structured by a combination of a metal ring  26 , and a rubber-like elastic body  27  attached (adhered in a vulcanizing manner) to the metal ring  26 . 
         [0066]    The metal ring  26  is made of a metal material such as a sheet metal or the like, is obtained by integrally forming an annular radially rising part (a flat surface part)  26   b  on an end portion at the other side (a right side of the drawing) in an axial direction of the tubular part  26   a  so as to extend outward in a radial direction (upward in the drawing), and is fitly attached to an outer peripheral surface of a bearing inner ring by the former tubular part  26   a.    
         [0067]    The rubber-like elastic body  27  integrally has an inner peripheral rubber part  27   a  attached to a distal end inner peripheral surface of the tubular part  26   a  of the metal ring  26 , a distal end rubber part  27   b  attached to a distal end surface of the tubular part  26   a,  an outer peripheral rubber part  27   c  attached to an outer peripheral surface of the tubular part  26   a,  an end surface rubber part  27   d  attached to an inner side end surface of the radially rising part  26   b  of the metal ring  26 , a seal lip (a radial lip)  27   e  supported by the end surface rubber part  27   d  and slidably brought into close contact with an inner peripheral surface of the tubular part  24   a  of the metal ring  24  in the outer peripheral side sealing member  22 , and a seal lip (a side lip)  27   f  supported by the end surface rubber part  27   d  in the same manner and slidably brought into close contact with an inner side end surface of the radially rising part  24   b  of the metal ring  24  in the outer peripheral side sealing member  22 . 
         [0068]    Further, an inner peripheral tube part  24   c  is integrally formed on a distal end of the radially rising part  24   b  corresponding to an innermost peripheral portion of the metal ring  24  in the outer peripheral side sealing member  22  so as to extend toward one side in an axial direction, whereby the metal ring  24  is formed in an approximately C-shaped cross section as a whole. 
         [0069]    Further, an annular protruding part  27   g  is integrally formed on an end surface rubber part  27   d  of a rubber-like elastic body  27  in the lip seal  25  so as to extend toward one side in an axial direction, in such a manner as to be positioned at an outer peripheral side of the inner peripheral tube part  24   c,  and the protruding part  27   g  has a tubular inner peripheral surface  27   h.    
         [0070]    Therefore, in accordance with the structure mentioned above, since the labyrinth spaces  28 ,  29  and  31  each having a small gap are formed between the outer peripheral surface of the inner peripheral tube part  24   c  and the inner peripheral surface  27   h  of the protruding part  27   g,  between the distal end surface of the inner peripheral tube part  24   c  and the inner side end surface of the end surface rubber part  27   d  and between the inner peripheral surface of the inner peripheral tube part  24   c  and the outer peripheral surface of the outer peripheral rubber part  27   c,  and the labyrinth spaces  28 ,  29  and  31  at these three positions are formed in an approximately C-shaped cross section and are structured such as to be sequent in series, an overall length of a labyrinth seal  30  generated by the labyrinth spaces  28 ,  29  and  31  is set further longer than the case of the third embodiment mentioned above, in addition to the same operations and effects as achieved in the third embodiment mentioned above. Therefore, it is possible to further increase the sealing performance in accordance that the length of the labyrinth seal  30  is set longer as mentioned above.