Patent Publication Number: US-2011068542-A1

Title: Sealing device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a national stage of International Application No. PCT/JP2009/060217 filed on Jun. 4, 2009 and published in the Japanese language. This application claims the benefit of Japanese Patent Application No. 2008-150030 filed on Jun. 9, 2008. The disclosures of the above applications are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a sealing device sealing an outer periphery of a rotating body in a motor vehicle, a general machinery, an industrial machinery or the like by a seal lip. 
     2. Description of the Conventional Art 
     As a sealing device sealing an outer periphery of a rotating body by a seal lip, an oil seal has been known.  FIG. 6  is a half sectional view showing an oil seal as a conventional sealing device by cutting it along a plane passing through an axis O thereof. 
     An oil seal  100  shown in  FIG. 6  is formed in an annular shape by a rubber-like elastic material, and is structured such that an attaching portion  101  at an outer periphery and a seal lip  103  at an inner peripheral side thereof are formed continuously with each other via a lip holder portion  102 , and a metal ring  104  for reinforcing is integrally embedded from the attaching portion  101  to the lip holder portion  102 . Further, an outer periphery of the seal lip  103  is formed in a groove shape which is continuous in a circumferential direction, and a garter spring  105  for compensating for tension force of the seal lip  103  is fitly attached. 
     Further, in the oil seal  100 , the attaching portion  101  is closely fitted to an inner peripheral surface of the housing  110 , and a distal end inner peripheral portion of the seal lip  103  oriented to an in-machine A side is slidably brought into close contact with an outer peripheral surface of a rotating shaft  120  inserted into the housing  110 , whereby the oil seal  100  achieves a shaft sealing function, and prevents a lubricating oil in the in-machine A side from leaking out of a shaft periphery to a machine outside B. 
     In this kind of oil seal  100 , lubrication of a sliding portion of the seal lip  103  with respect to the outer peripheral surface of the rotating shaft  120  depends on lubricating oil to be sealed in the in-machine A side. However, in the case of being used under an environment of a high peripheral speed and a high temperature, it is necessary to supply more lubricating oil to the vicinity of the seal lip  103  for the purpose of cooling the seal lip  103 . Accordingly, as described in the following patent documents, there has been conventionally a structure in which lubricating oil passing through a bearing in an in-machine side is supplied to the vicinity of a seal lip on the basis of centrifugal force, however, a supply efficiency is low and a cooling of the seal lip is not necessarily sufficient. 
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     The present invention is made by taking the points mentioned above into consideration, and a technical problem of the present invention is to provide a sealing device which sufficiently supplies lubricating oil to a sliding portion of a seal lip, whereby it is possible to suppress heat generation and abrasion of the seal lip. 
     Means for Solving the Problem 
     As a means for effectively solving the technical problem mentioned above, in accordance with the present invention, there is provided a sealing device comprising a sealing device main body in which a seal lip oriented to an in-machine side is slidably brought into close contact with an outer peripheral surface of a rotating body, and a pumping device provided in combination with the sealing device main body, wherein the pumping device has a helical groove, which is positioned at the in-machine side of the seal lip, is formed in a surface opposed to an outer peripheral surface of the rotating body and feeds fluid to the seal lip side on the basis of rotation of the rotating body, and discharge flow passages which make a space between the sealing device main body and the pumping device communicate with the machine inside side. 
     In accordance with the structure mentioned above, since the helical groove of the pumping device feeds the lubricating oil in the in-machine side to the seal lip side (the space between the sealing device main body and the pumping device) on the basis of the rotation of the rotating body, the sliding portion between the seal lip and the rotating body is lubricated. Further, the lubricating oil is reflowed to the in-machine side from the space between the sealing device main body and the pumping device via the discharge flow passages. Accordingly, a flow in one direction of the lubricating oil is generated, thereby preventing the lubricating oil from being deteriorated and being raised in its oil temperature due to retention of the lubricating oil, and a cooling efficiency of the seal lip is improved. 
     EFFECT OF THE INVENTION 
     In accordance with the sealing device of the present invention, since the lubricating oil is supplied at a sufficient flow rate to the sliding portion of the seal lip, it is possible to efficiently cool the seal lip as well as to suppress abrasion of the seal lip. As a result, a good sealing function can be maintained over a long term. 
    
    
     
       BRIEF EXPLANATION OF DRAWINGS 
         FIG. 1  is a half sectional view showing a first embodiment of a sealing device in accordance with the present invention by cutting it along a plane passing through an axis O; 
         FIG. 2  is a sectional view of a substantial part showing a variation of a sectional shape of a helical groove in a pumping device used in the present invention; 
         FIG. 3  is a sectional view showing a second embodiment of the sealing device in accordance with the present invention by cutting it along a plane passing through an axis O; 
         FIG. 4  is a half sectional view showing a third embodiment of the sealing device in accordance with the present invention by cutting it along a plane passing through an axis O; 
         FIG. 5  is a partial sectional view showing a specific example of the sealing device in accordance with the present invention by cutting it along a plane passing through an axis O; and 
         FIG. 6  is a half sectional view showing an oil seal as a conventional sealing device by cutting it along a plane passing through an axis O. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     A description will be given below of preferred embodiments of a sealing device in accordance with the present invention with reference to the accompanying drawings.  FIG. 1  is a half sectional view showing a first embodiment of a sealing device in accordance with the present invention by cutting it along a plane passing through an axis O, and  FIG. 2  is a sectional view of a substantial part showing a variation of a sectional shape of a helical groove in a pumping device used in the present invention. 
     First of all, in  FIG. 1 , reference numeral  3  denotes a housing of an equipment, and reference numeral  4  denotes a rotating shaft inserted to an inner periphery of the housing  3 . The sealing device in accordance with the first embodiment is constructed by a sealing device main body  1  in which a seal lip  13  oriented to an in-machine A side is slidably brought into close contact with an outer peripheral surface of the rotating shaft  4 , and a pumping device  2  provided in combination with the sealing device main body  1 . In this case, the rotating shaft  4  corresponds to a rotating body described in claim  1 . 
     The sealing device main body  1  is provided with a configuration for serving as a so-called oil seal, and is integrally formed in a metal ring  15  by a rubber material or a synthetic resin material having a rubber-like elasticity. In other words, the sealing device main body  1  has an approximately cylindrical attaching portion  11 , a lip holder portion  12  extending to an inner peripheral side from an end portion at an out-machine B side, a seal lip  13  extending toward the in-machine A side from a radially inner end of the lip holder portion  12  in such a manner as to form an approximately C-shaped cross section together with the attaching portion  11  and the lip holder portion  12 , a dust lip  14  extending toward an opposite side to the seal lip  13  (out-machine B side) from an inner peripheral end of the lip holder portion  12 , a reinforcing metal ring  15  embedded in both the attaching portion  11  and the lip holder portion  12 , and a garter spring  16  fitly attached to the seal lip  13 . 
     The attaching portion  11  in the sealing device main body  1  is a portion which is pressed into and closely fitted to an inner peripheral surface of the housing  3 , and is structured such as to be properly compressed in a radial direction between the metal ring  15  and the inner peripheral surface of the housing  3  in the state of installation. 
     A seal edge  13   a  having an approximately V-shaped cross section is formed on an inner periphery in the vicinity of a distal end portion of the seal lip  13  in the sealing device main body  1 , and the seal edge  13   a  is structured such as to be slidably brought into close contact with an outer peripheral surface of the rotating shaft  4  with a suitable fastening margin. On the other hand, the dust lip  14  oriented to an opposite side to the seal lip  13  is structured such that an inner peripheral edge thereof comes close to the outer peripheral surface of the rotating shaft  4  with a micro gap, or is slidably brought into close contact with a slight fastening margin. 
     The garter spring  16  is made by metal coil springs being annularly connected, is fitly attached to an annular groove formed at the outer peripheral side of the seal edge  13   a  in the seal lip  13 , and is structured such as to compensate for tension force of the seal lip  13  with respect to the outer peripheral surface of the rotating shaft  4 . 
     The pumping device  2  is constructed by a metal ring  21 , and a helical pump portion  22  integrally provided therein. Describing in detail, the metal ring  21  in the pumping device  2  is constructed by a fitted tube portion  21   a  which is pressed into and fitted to an inner peripheral surface of the attaching portion  11  in the sealing device main body  1 , and a flange portion  21   b  which extends in a radially inward direction from an end portion at the in-machine A side thereof and has a larger inner diameter than the diameter of the rotating shaft  4 , and the helical pump portion  22  is formed in an annular shape on the flange portion  21   b  by a rubber material, a synthetic resin material having a rubber-like elasticity or a synthetic resin material having no rubber-like elasticity. In other words, the pumping device  2  is previously integrally attached to the attaching portion  11  of the sealing device main body  1  in accordance with press fitting. 
     The helical pump portion  22  in the pumping device  2  is structured such that a helical groove  2   a  feeding fluid to the seal lip  13  side in the sealing device main body  1  on the basis of rotation in a direction R of the rotating shaft  4  is formed in an inner peripheral surface which is close to and is opposed to the outer peripheral surface of the rotating shaft  4 . Further, discharge flow passages  2   b  making a space C between the sealing device main body  1  and the pumping device  2  communicate with the in-machine A side are provided at a plurality of positions in a circumferential direction in a radially outer portion of the flange portion  21   b  of the metal ring  21 , which is exposed outside the helical pump portion  22 . 
     In this case, when an angle of the helical groove  2   a  with respect to a rotating direction of the rotating shaft  4  is defined to θ, it is preferable to satisfy the relation of 0&lt;θ≦45 degree. 
     Further, as for a sectional shape of the helical groove  2   a , there can be thought a trapezoidal shape as shown in  FIG. 2A  and a semicircular shape as shown in  FIG. 2B  in addition to a rectangular shape as shown in  FIG. 1 , and it is not particularly limited. 
     On the basis of the sealing device in accordance with the first embodiment structured as mentioned above, the sealing device main body  1  is structured such that the attaching portion  11  is pressed into and fitted to the inner peripheral surface of the housing  3  in such a manner that the seal lip  13  is oriented to the in-machine A side, and the seal edge  13   a  of the inner periphery of the seal lip  13  is slidably brought into close contact with the outer peripheral surface of the rotating shaft  4 . Further, the pumping device  2  previously attached to the sealing device main body  1  comes to a state of being arranged at the in-machine A side of the sealing device main body  1 . 
     In such the installed state of the sealing device main body  1 , the seal edge  13   a  of the seal lip  13  is slidably brought into close contact with the outer peripheral surface of the rotating shaft  4 , whereby lubricating oil supplied for lubricating, for example, a bearing (not shown) or the like in the in-machine A side is prevented from leaking to atmospheric air at the out-machine B side from a shaft periphery of the rotating shaft  4 , and a foreign material in the atmospheric air at the out-machine B side is prevented from making an intrusion by means of the dust lip  14 . 
     Further, since the pumping device  2  achieves a helical pump function of discharging fluid interposed between the rotating shaft  4  and the helical groove  2   a  of the helical pump portion  22  to the seal lip  13  side on the basis of the rotation of the rotating shaft  4 , that is, the lubricating oil in the in-machine A side is forcibly fed to the seal lip  13  through the helical groove  2   a , a sliding portion between the seal lip  13  and the rotating shaft  4  is well lubricated. 
     Further, the lubricating oil supplied to the sliding portion between the seal lip  13  and the rotating shaft  4  is reflowed to the in-machine A side from the space C between the sealing device main body  1  and the pumping device  2  via the discharge flow passages  2   b  provided in a radially outer portion of the flange portion  21   b  of the metal ring  21 . Accordingly, since a flow in one direction heading for the discharge flow passages  2   b  from the inner periphery of the helical pump portion  22  via the sliding portion between the seal lip  13  and the rotating shaft  4  is generated in the space C between the sealing device main body and the pumping device  2 , it is possible to prevent the lubricating oil from being deteriorated due to its retention and prevent an oil temperature from rising, and the seal lip  13  can be efficiently cooled. 
     Next,  FIG. 3  is a half sectional view showing a second embodiment of the sealing device in accordance with the present invention by cutting it along a plane passing through an axis O, and  FIG. 4  is a half sectional view showing a third embodiment of the sealing device in accordance with the present invention by cutting it along a plane passing through an axis O. 
     In these embodiments, a difference from the first embodiment shown in  FIG. 1  exists in a point that the pumping device  2  is constructed only by a pumping ring  23  which is formed by a rubber material, a synthetic resin material having a rubber-like elasticity or a synthetic resin material having no rubber-like elasticity, is provided in combination at the in-machine A side of the sealing device main body  1  and is attached to the inner peripheral surface of the housing  3  in accordance with a press fitting. 
     The pumping ring  23  is structured such that a helical groove  2   a  for feeding fluid to the seal lip  13  side in the sealing device main body  1  on the basis of rotation in a direction R of the rotating shaft  4  is formed in an inner peripheral surface which is close to and is opposed to the outer peripheral surface of the rotating shaft  4 , and discharge flow passages  2   b  making a space C between the sealing device main body  1  and the pumping device  2  communicate with the in-machine A side are provided at a plurality of positions in a circumferential direction, in the pumping ring  23 . 
     In the second embodiment shown in  FIG. 3 , the discharge flow passages  2   b  are constructed by a plurality of holes passing through the pumping ring  23  in an axial direction, and in the third embodiment shown in  FIG. 4 , the discharge flow passages  2   b  are formed between a plurality of grooves extending in an axial direction along an outer peripheral surface of the pumping ring  23  and the inner peripheral surface of the housing  3 . 
     In this case, the sealing device main body  1  is provided basically with the same structure as that of the first embodiment ( FIG. 1 ) which has been previously described. 
     On the basis of the sealing device in accordance with the second or third embodiment structured as mentioned above, the sealing device main body  1  is structured such that the attaching portion  11  is pressed into and fitted to the inner peripheral surface of the housing  3  in such a manner that the seal lip  13  is oriented to the in-machine A side, and the seal edge  13   a  on the inner periphery of the seal lip  13  is slidably brought into close contact with the outer peripheral surface of the rotating shaft  4 . Further, the pumping device  2  (the pumping ring  23 ) is positioned at the in-machine A side of the sealing device main body  1  so as to be pressed into and fitted to the inner peripheral surface of the housing  3 . 
     In such the installed state of the sealing device main body  1 , lubricating oil supplied for lubricating, for example, a bearing (not shown) or the like in the in-machine A side is prevented from leaking to atmospheric air at the out-machine B side from a shaft periphery of the rotating shaft  4  by means of the seal lip  13 , and a foreign material in the atmospheric air at the out-machine B side is prevented from making an intrusion by means of the dust lip  14 , in the same manner as that of the first embodiment. 
     Further, since the pumping device  2  achieves a helical pump function of discharging fluid interposed between the rotating shaft  4  and the helical groove  2   a  of the pumping ring  23  to the seal lip  13  side on the basis of the rotation of the rotating shaft  4 , that is, the lubricating oil in the in-machine A side is forcibly fed to the seal lip  13  through the helical groove  2   a , a sliding portion between the seal lip  13  and the rotating shaft  4  is well lubricated. 
     Further, the lubricating oil supplied to the sliding portion between the seal lip  13  and the rotating shaft  4  is reflowed to the in-machine A side from the space C between the sealing device main body  1  and the pumping device  2  via the discharge flow passages  2   b . Accordingly, since a flow in one direction heading for the discharge flow passages  2   b  from the inner periphery of the pumping ring  23  via the sliding portion between the seal lip  13  and the rotating shaft  4  is generated in the space C between the sealing device main body  1  and the pumping device  2 , it is possible to prevent the lubricating oil from being deteriorated due to its retention and prevent an oil temperature from rising, and the seal lip  13  can be efficiently cooled. 
     Example 
       FIG. 5  is a partial sectional view showing a specific example of the sealing device in accordance with the present invention by cutting it along a plane passing through an axis O. In this  FIG. 5 , reference numeral  201  denotes a cylinder block of an internal combustion engine, reference numeral  202  denotes an output shaft which is supported to the cylinder block  201  via a first bearing  203  in a rotatable state, and reference numeral  204  denotes a ring gear which is provided on a shaft end of the output shaft  202  so as to be relatively rotatable with the output shaft  202  via a second bearing  205 . Describing in detail, an outer ring  205   a  of the second bearing  205  is fixed to an inner portion of the ring gear  204 , an inner ring  205   b  of the second bearing  205  is fixed to an outer peripheral surface of a flange  202   a  formed on the shaft end of the output shaft  202 , and the ring gear  204  is engaged with a pinion gear of a starting motor (not shown). 
     Further, a one way clutch  206  transmitting a rotating force only to the output shaft  202  from the ring gear  204  is interposed between the ring gear  204  and the output shaft  202 . Describing in detail, an inner race  206   a  of the one way clutch  206  is fixed to an inner portion of the ring gear  204 , and an outer race  206   b  of the one way clutch  206  is fixed to the output shaft  202  via a coupling plate  207  which is attached to the flange  202   a  on the shaft end thereof together with a flywheel  210  by a bolt  202   b.    
     In other words, at a time of starting of the internal combustion engine, if the ring gear  204  is rotated by the starting motor (not shown), rotating force thereof is transmitted to the output shaft  202  from the one way clutch  206 , whereby driving of the internal combustion engine is started. Further, an engagement of the one way clutch  206  is released at a time point when the rotating speed of the output shaft  202  increases beyond the rotating speed of the ring gear  204 , the starting motor is stopped at a time point when the rotating speed of it increases up to a predetermined rotating speed, and the ring gear  204  stops. 
     Further, lubricating oil is supplied to the sliding portion between the first bearing  203  and the output shaft  202  from an oil pan (not shown) through an oil passage  209  by a hydraulic pump  208 , a part of the lubricating oil flows out in an outward radial direction through a gap G 1  between the flange  202   a  of the output shaft  202  and the cylinder block  201 , further a part thereof is supplied to the second bearing  205 , and the lubricating oil passing through a portion between the outer ring  205   a  and the inner ring  205   b  of the second bearing  205  flows out further in the outward radial direction from a gap G 2  between the coupling plate  207  and the second bearing  205  on the basis of centrifugal force, and is supplied to the sliding portion of the one way clutch  206 . 
     In order to prevent the lubricating oil flowing out in the outward radial direction through the gap G 1  between the flange  202   a  of the output shaft  202  and the cylinder block  201 , and the lubricating oil supplied to the second bearing  205  and the one way clutch  206  from the gap G 1  from flowing further to the out-machine side from a gap G 3  between the outer race  206   b  of the one way clutch  206  and the ring gear  204  via a space in an outer peripheral side of the outer race  206   b  and a gap G 4  between the ring gear  204  and the flywheel  210 , and securely collect the lubricating oil into the oil pan (not shown), a sealing device is provided between the outer race  206   b  of the one way clutch  206  and a cylindrical housing  204   a  positioned at an outer peripheral side thereof and formed in the ring gear  204 . The structure in accordance with the present invention can be preferably applied to this sealing device. In other words, the sealing device in this example is provided with the sealing device main body  1 , and the pumping device  2  provided in combination in the axial direction with the sealing device main body  1 , and they are both attached to an inner peripheral surface of the housing  204   a.    
     Describing in detail, the sealing device main body  1  has the seal lip  13  oriented to the in-machine side (the cylinder block  201  side), and the seal lip  13  is slidably brought into close contact with an outer peripheral surface of the outer race  206   b  corresponding to the rotating body. On the other hand, the pumping device  2  is positioned at the cylinder block  201  side of the seal lip  13 , the helical groove  2   a  feeding the fluid to the seal lip  13  side on the basis of the rotation of the outer race  206   b  is formed in an inner peripheral surface opposed to the outer peripheral surface of the outer race  206   b , and the discharge flow passages  2   b  making the space between the sealing device main body  1  and the pumping device  2  communicate with the space at the cylinder block  201  side via window portions  204   b  provided in the ring gear  204  are provided. 
     In this case, as has been described previously, since the ring gear  204  stops after the internal combustion engine is started by the starting motor (not shown), the lubricating oil has been conventionally hard to be supplied to the sliding portion between the seal lip  13  and the outer peripheral surface of the outer race  206   b . However, if the structure in accordance with the present invention is applied, the helical groove  2   a  of the pumping device  2  achieves the helical pump function of feeding the lubricating oil passing through the second bearing  205  and the one way clutch  206  and reaching the inner periphery of the pumping device  2  from the gap G 3  between the outer race  206   b  of the one way clutch  206  and the ring gear  204  to the seal lip  13  side on the basis of the rotation of the outer race  206   b , and the sliding portion between the seal lip  13  and the outer race  206   b  is accordingly lubricated well. 
     Further, the lubricating oil supplied to the sliding portion between the seal lip  13  and the outer race  206   b  is reflowed to the in-machine side from the space between the sealing device main body  1  and the pumping device  2 , via the discharge flow passages  2   b  and the window portions  204   b  of the ring gear  204 . Accordingly, it is possible to prevent the lubricating oil from being deteriorated due to the retention and prevent the oil temperature from rising, and the seal lip  13  is efficiently cooled.