Sealing device, and rolling bearing and hub unit incorporating the sealing unit

Abstract

A seal member with its base end connected to a metal core has three seal lips. The thickness of the tip end of the intermediate seal lip in the intermediate position is d 1 , and the thickness of the base end is d 2 . The thickness of the tip end of the innermost inner seal lip is D 1 and that thickness of the base end is D 2 . In this case, at least part of the base end of the intermediate seal lip and inner seal lip has its thickness regulated to be 0.2·d 1 ≦d 2 ≦0.8·d 1 , and 0.5·D 1 ≦D 2 <D 1 . The tip edge of the inner seal lip is fitted onto the outer peripheral surface of the radially inside cylindrical portion of a slinger with substantially zero interference. Consequently, even if the slinger and metal core are displaced relative to each other, excellent seal performance is secured while increase of torque is inhibited.

1 . A seal assembly to be incorporated in a rolling bearing comprising an inner race having an outer peripheral surface formed with an inner raceway, an outer race having an inner peripheral surface formed with an outer raceway, and a plurality of rolling members provided between the inner raceway and outer raceway for relative rotation between the inner race and outer race, the seal assembly having a support member and a seal member to cover a space between the outer peripheral surface at the end of the inner race and the inner peripheral surface at the end of the outer race, the support member being fixed to one of the outer peripheral surface at the end of the inner race and the inner peripheral surface at the end of the outer race, the seal member having a plurality of seal lips made of resilient material and a portion connected and fixed to the support member, an inner seal lip being located at the innermost location in the plurality of seal lips and an intermediate seal lip being located adjacent the inner seal lip on the axially outer side thereof, the other of the outer peripheral surface at the end of the inner race and the inner peripheral surface at the end of the outer race supporting a member, either the other of the outer peripheral surface at the end of the inner race and the inner peripheral surface at the end of the outer race or the member having a radially oriented peripheral surface, and the inner seal lip and intermediate seal lip having a tip edge come into sliding contact with the radially oriented peripheral surface, wherein, provided that d 1  is the thickness of the tip edge of the intermediate seal lip, that d 2  is the thickness of the base end of the intermediate seal lip, that D 1  is the thickness of the tip edge of the inner seal lip, that D 2  is the thickness of the base end of the inner seal lip, the relations in thickness of 0.2 d 1 ≦d 2 ≦0.8 d 1  and of 0.5 D1≦D 2   D 1  are satisfied in at least a portion of the base end of the intermediate seal lip and inner seal lip, wherein the seal lip experiences no or slight resilient deformation with substantially zero interference when the tip edge of the inner seal lip and intermediate seal lip comes into sliding contact with the radially oriented peripheral surface.  
   
   
       2 . A seal assembly to be incorporated in a rolling bearing comprising an inner race having an outer peripheral surface formed with an inner raceway, an outer race having an inner peripheral surface formed with an outer raceway, and a plurality of rolling members provided between the inner raceway and outer raceway for relative rotation between the inner race and outer race, the sealing assembly having a circular-ring shaped metal core, a circular-ring shaped annular member, a seal member, an axially oriented seal lip and a radially oriented seal lip to cover a space between the outer peripheral surface at the end of the inner race and the inner peripheral surface at the end of the outer race, the metal core having a radially outer cylindrical portion fitted and fixed into the inner peripheral surface at the end of the outer race and an inner circular ring portion bent radially inwards from the axially inner end edge of the radially outer cylindrical portion, the annular member having a radially inner cylindrical portion fitted and fixed onto the outer peripheral surface at the end of the inner race and an outer circular ring portion bent radially outwards from the axially outer end edge of the radially inner cylindrical portion, the seal member being made of a resilient material and having a portion connected and fixed to at least one of the metal core and annular member, the axially oriented seal lip being provided in a portion of the seal member and having its tip edge come into sliding contact with the axially oriented side surface of a rotational member which rotates relative to the metal core or annular member to which the seal member is fixed, the radially oriented seal lip being provided in a portion of the seal member and having its tip edge come into sliding contact with the radially oriented peripheral surface of the rotational member which rotates relative to the metal core or annular member to which the seal member is fixed, wherein, provided that the radially oriented seal lip has a base end and tip edge such that the thickness of the base end in at least part thereof is smaller than the thickness of the tip edge, and provided that L 1  is the radial interference of the rotational member having the radially oriented peripheral surface, between the tip edge of the radially oriented seal lip and the radially oriented peripheral surface, that L 2  is the axial interference of the rotational member having the axially oriented side surface, between the tip edge of the axially oriented seal lip and the axially oriented side surface, and that R is the diameter of the fitting portion between the outer peripheral surface of the inner race and the radially inner cylindrical portion, the relations of 0.010≦L 1 /r≦0.020 and 0.008≦L 2 /R≦0.15 are satisfied.  
   
   
       3 . A seal assembly to be incorporated in a rolling bearing comprising an inner race having an outer peripheral surface formed with an inner raceway, an outer race having an inner peripheral surface formed with an outer raceway, and a plurality of rolling members provided between the inner raceway and outer raceway for relative rotation between the inner race and outer race, the sealing assembly having a support member, a seal member and an axial seal lip to cover a space between the outer peripheral surface at the end of the inner race, and the inner peripheral surface at the end of the outer race, the support member fixed to one of the outer peripheral surface at the end of the inner race, and the inner peripheral surface at the end of the outer race, the seal member having a part connected and fixed to the support member and made of a resilient member, the axial seal lip provided in part of the seal member and having its tip edge come into contact with the axially directed side surface provided on the other of the outer peripheral surface at the end of the inner race and the inner peripheral surface at the end of the outer race, or on the axially directed side surface of a member supported by the other, wherein, provided that a center point is defined as a position on the phantom line passing through the center in the thickness direction of the axially oriented seal lip with the length from the tip end to the position being equal to the length from the base end to the position, t 1  is the thickness of the axially oriented seal lip at the base end, t 2  at the center point and t 3  at the tip end the relationship 0.70<t 2 /t 1 <0.85 and 0.35<t 3 /t 1 <0.65 is satisfied.  
   
   
       4 . A seal assembly to be incorporated in a rolling bearing comprising an inner race having an outer peripheral surface formed with an inner raceway, an outer race having an inner peripheral surface formed with an outer raceway, and a plurality of rolling members provided between the inner raceway and outer raceway for relative rotation between the inner race and outer race, the sealing assembly having a support member, a seal member and an axial seal lip to cover a space between the outer peripheral surface at the end of the inner race and the inner peripheral surface at the end of the outer race, the support member fixed to one of the outer peripheral surface at the end of the inner race, and the inner peripheral surface at the end of the outer race, the seal member having its part connected and fixed to the support member and made of a resilient member, the axial seal lip provided in part of the seal member and having its tip edge come into contact with the axially directed side surface provided on the other of the outer peripheral surface at the end of the inner race and the inner peripheral surface at the end of the outer race, or on the axially directed side surface of a member supported by the other, wherein a projection is formed on the side surface of the tip end portion of the axially oriented seal lip which is radially inwardly oriented in the free state thereof, that the tip edge of this projection comes in slidable contact with the axially oriented side surface provided in the other of the outer peripheral surface of the end portion of the inner race and the inner peripheral surface of the end portion of the outer race or with the axially oriented side surface of the member supported by the other peripheral surface.  
   
   
       5 . A seal assembly to be incorporated in a rolling bearing comprising an inner race having an outer peripheral surface formed with an inner raceway, an outer race having an inner peripheral surface formed with an outer raceway, and a plurality of rolling members provided between the inner raceway and outer raceway for relative rotation between the inner race and outer race, the sealing assembly having a support member, a seal member and an axial seal lip to cover a space between the outer peripheral surface at the end of the inner race and the inner peripheral surface at the end of the outer race, the support member fixed to one of the outer peripheral surface at the end of the inner race, and the inner peripheral surface at the end of the outer race, the seal member having a part connected and fixed to the support member and made of a resilient member, the axial seal lip provided in part of the seal member and having its tip edge come into contact with the axially directed side surface provided on the other of the outer peripheral surface at the end of the inner race and the inner peripheral surface at the end of the outer race, or on the axially directed side surface of a member supported by the other, wherein the thickness of the axially oriented seal lip is gradually decreasing, except for the tip end portion, from the base end portion to a position of the intermediate portion close to the tip end, that the thickness from this position of the intermediate portion to the tip edge is gradually increased toward the tip edge, and that the tip edge comes into sliding contact with the axially directed side surface.  
   
   
       6 . A seal assembly to be incorporated in a rolling bearing comprising an inner race having an outer peripheral surface formed with an inner raceway, an outer race having an inner peripheral surface formed with an outer raceway, and a plurality of rolling members provided between the inner raceway and outer raceway for relative rotation between the inner race and outer race, the sealing assembly having a support member, a seal member and an axial seal lip to cover a space between the outer peripheral surface at the end of the inner race and the inner peripheral surface at the end of the outer race, the support member fixed to one of the outer peripheral surface at the end of the inner race, and the inner peripheral surface at the end of the outer race, the seal member having a part connected and fixed to the support member and made of a resilient member, the axial seal lip provided in part of the seal member and having its tip edge come into contact with the axially directed side surface provided on the other of the outer peripheral surface at the end of the inner race and the inner peripheral surface at the end of the outer race, or on the axially directed side surface of a member supported by the other, the wherein an auxiliary seal lip is provided to project from the radially outer end of the tip edge of the axially directed seal lip, that the tip edge of the auxiliary seal lip and the radially inner end of the tip edge of the axially oriented seal lip separated from this auxiliary seal lip are arranged to come in slidable contact with the axially oriented side surface provided in the other of the outer peripheral surface of the end portion of the inner race and the inner peripheral surface of the end portion of the outer race or with the axially oriented side surface of the member supported by the other peripheral surface.  
   
   
       7 . A rolling bearing having at least one of the seal assemblies of any one of  claims 1  to  6  installed therein.  
   
   
       8 . A hub unit having at least one of the seal assemblies of any one of  claims 1  to  6  installed therein, wherein the inner race is a hub for fixing a wheel thereto.