JP2009216140A - Sealing device for bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing sealing device comprising an axial direction subsidiary seal lip, in which stick slip is less likely to occur even when axial direction interference of the subsidiary seal lip is increased. <P>SOLUTION: The subsidiary seal lip 94 is formed to diagonally rise radially outward from an axial base surface 8b of a slidable seal part 8. A circular branch seal lip 95 is formed on a radial direction inner circumferential surface of the subsidiary seal lip 94 to project toward an inner surface of an inner ring side slinger 10. While an outer ring 4 is not rotating, a tip of the branch seal lip 95 is put to the inner surface of the inner ring side slinger 10 to slide. The tip of the branch seal lip 95 forms a linear slide contact surface, while the radial direction inner circumferential surface of the subsidiary seal lip 94 at a lip tip part 94t forms a gap at least on the adjoining side to the branch seal lip 95, using the branch seal lip 95 for a spacer. Since a noncontact area is thus generated, slide surface is less likely to be excessively large even when the axial direction interference of the subsidiary seal lip 94 is increased, thereby occurrence of stick slip is restricted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a bearing sealing device.

JP 2003-194077 A JP 2005-282669 A

  Due to demands for smaller and lighter automobiles and further expansion of living space, the engine room space has been inevitably reduced, and electrical components and engine accessories have been further reduced in size and weight. Electromagnetic clutches and compressors for car air conditioners The idler pulley is no exception. However, a reduction in output is unavoidable due to downsizing, and an electromagnetic clutch compensates for the reduction in output by increasing the speed, and accordingly, the idler pulley is also increased in speed. Furthermore, since the engine room is being sealed due to a demand for improvement in quietness, and the high temperature in the engine room is promoted, these parts are also required to withstand high temperatures. In addition, since these parts are often attached to the lower part of the engine room, they are likely to be exposed to rain water, muddy water, etc. during traveling, and high sealing performance is required for the rolling bearings for these parts.

  Roller bearings for idler pulleys are used in such a manner that the inner ring is on the non-rotating side and the outer ring on which the pulley is fixed is on the rotating side. Such a rolling bearing sealing device includes a rubber main seal lip formed on the radially inner peripheral edge of the outer peripheral edge of the outer ring so as to be relatively non-rotatably fitted to the inner peripheral side of the axial end of the outer ring. However, it has a sliding seal part which slidably contacts the outer peripheral side of the axial end of the inner ring. In Patent Document 1, an inner ring side slinger (dust cover) fitted to a non-rotating inner ring is arranged oppositely on the outer side in the axial direction of such a sliding seal portion to suppress intrusion of dust or the like into the bearing. ing.

  In recent years, the conditions of use of automobiles have become more severe, and there are cases in which further increase in the amount of water is expected, such as when splashed muddy water or car wash water is jetted at a strong pressure, and flooding seen in RV cars, etc. Considering use in a submerged state or a submerged state, the bearing sealing device is required to have higher waterproofness. In Patent Document 2, a secondary seal lip (axial lip) that protrudes toward the inner ring-side slinger and contacts the inner surface of the slinger is formed on the outer surface in the axial direction of the sliding seal portion to further improve the sealing performance.

  However, in the configuration of Patent Document 2, the sub-seal lip has a flat front end surface and is inclined in the radial direction outward, and is in sliding contact with the inner ring side slinger at the front end surface. In such a structure, there is no problem if the secondary seal lip is elastically deformed by the centrifugal force accompanying the rotation of the outer ring and the axial interference is reduced appropriately, but the rotational speed is reduced and the interference is increased. As a result, the wear of the lip portion progresses to increase the sliding contact area and the bearing torque is likely to increase, and abnormal noise due to stick-slip is likely to occur. In particular, when the bearing temperature rises due to rotational friction, etc., and then cooled, the inside of the bearing may become negative pressure, and the suction force may further increase the tightening margin of the secondary seal lip, further causing stick slip. It becomes easy to do.

  SUMMARY OF THE INVENTION An object of the present invention is to make it difficult for stick-slip to occur in a bearing sealing device having an auxiliary seal lip in the axial direction even when the axial seal margin of the auxiliary seal lip increases.

Means for Solving the Problems and Effects of the Invention

The present invention is a bearing sealing device used for a radial bearing used in outer ring rotation, in order to solve the above problems,
An inner ring-side slinger that is arranged in such a manner as to block the annular opening of the rolling element arrangement space formed between the inner and outer rings in the axial direction, and the radially inner peripheral edge fits in the axial direction end of the inner ring in a relatively non-rotatable manner;
The inner ring side slinger is placed facing the inner ring in the axial direction to form an axial seal gap. The outer peripheral edge of the radial direction is fitted to the axial end of the outer ring in a relatively non-rotatable manner, and the inner ring is positioned on the inner peripheral side of the radial direction. A main seal lip made of an elastic polymer material that is in sliding contact with the outer end of the axial direction is formed, and a sub-seal extending in the axial direction from the axial base surface with the surface facing the inner ring side slinger as an axial base surface A sliding seal part formed with a lip;
On the radially inner circumferential surface of the secondary seal lip, an annular branch seal lip is formed projecting toward the inner surface of the inner ring side slinger at an intermediate position in the radial direction, and the inner surface of the inner ring side slinger with the outer ring not rotated. The tip end of the branch seal lip is in sliding contact with the inner peripheral surface of the inner ring side slinger as the radial inner circumferential surface of the lip tip portion located closer to the tip end in the radial direction than the branch seal lip of the sub seal lip is closer to the tip of the lip. It is characterized in that the interval is reduced.

  According to the above configuration of the present invention, the sub seal lip rising obliquely outward in the radial direction from the axial base surface of the sliding seal portion is formed, and the annular branch seal is formed on the radial inner peripheral surface of the sub seal lip. A lip is formed so as to project toward the inner surface of the inner ring side slinger, and the tip of the branch seal lip is in sliding contact with the inner surface of the inner ring side slinger when the outer ring is not rotated. As a result, a linear sliding contact surface is formed at the tip of the branch seal lip, and the radial inner peripheral surface of the lip tip of the sub seal lip is at least the branch with the branch seal lip as a spacer. Since a gap is formed on the side adjacent to the seal lip and a non-contact region is generated, the sliding contact area is unlikely to be excessive even when the axial direction tightening margin of the sub seal lip is increased, and the occurrence of stick slip can be effectively suppressed.

  A configuration in which a gap forming a labyrinth seal is formed between the edge of the inner peripheral surface of the inner ring side slinger and the inner edge of the inner ring side slinger with respect to the lip tip of the secondary seal lip in a state where the outer ring is not rotated. It can be. In this case, when the lip tip of the secondary seal lip is not always in contact with the inner ring side slinger and the axial tightening margin increases, the sliding contact region is formed only at the tip of the branch seal lip. Is less likely to occur.

  On the other hand, when the outer ring is non-rotating, the radial inner peripheral surface tip edge of the lip tip of the sub seal lip is formed by the radial inner peripheral surface and the radial outer peripheral surface of the branch seal lip. It can also be set as the structure which slidably contacts the inner surface of the inner ring side slinger together with the branch seal lip. In this configuration, the sliding contact region is also formed at the lip tip of the secondary seal lip, so that the sealing performance can be improved and an annular shape is provided between the lip tip of the secondary seal lip and the branch seal lip. Since the groove forms a non-contact region, even when the axial tightening margin increases, the sliding area does not become excessively large and stick-slip hardly occurs.

  If the tip of the lip is configured to be in sliding contact with the inner surface of the inner ring side slinger as described above, the secondary seal lip can be elastically deformed in such a manner that it receives the centrifugal force accompanying the rotation of the outer ring and falls to the axial base surface side. The axial tightening allowance with respect to the lip tip is reduced as the centrifugal force decreases. That is, the sliding resistance of the lip tip portion of the sub seal lip is self-adjusted according to the bearing rotational speed, and a low rotational torque during high-speed rotation can be achieved.

  Next, when the rolling element arrangement space becomes negative pressure, the sub seal lip is elastically deformed inward in the radial direction. In this case, although the fastening margin of the branch seal lip is increased in the above configuration, the lip tip of the sub seal lip performs the following specific operation due to the presence of the branch seal lip. That is, the sub-seal lip is elastically deformed in the direction opposite to the deformation direction due to the centrifugal force with the generation of the negative pressure. At this time, with the branch seal lip as a fulcrum, the tip of the lip approaches and separates from the inner surface of the inner ring side slinger in a swinging manner according to the negative pressure. Specifically, the larger the negative pressure that acts, the more the lip tip swings away from the inner surface of the inner ring side slinger. As a result, the axial tightening margin of the lip tip of the sub seal lip during the negative pressure action is reduced by the swinging, and stick slip is less likely to occur.

  Next, the secondary seal lip has a sliding contact edge formed at the tip of the lip, and in a virtually undeformed state in which the inner ring side slinger is omitted, the sliding contact edge is a certain distance outside in the axial direction from the inner surface position of the inner ring side slinger. The tip of the lip with respect to the inner surface of the inner ring side slinger forms an annular belt-like slidable contact surface on the radially inner circumferential surface with the slidable contact edge as the contact start side. The radial width of the ring-shaped slidable contact surface formed between the lip tip and the inner ring-side slinger is reduced toward the slidable contact edge as the centrifugal force increases. Can be configured.

  According to the above configuration, the secondary seal lip that is in sliding contact with the inner ring side slinger has a sliding contact edge at the lip tip. When the inner ring side slinger is omitted and is virtually undeformed, the sliding contact edge is positioned outside by a certain distance in the axial direction from the inner surface position of the inner ring side slinger. When considered in the non-deformed state, the axial extension amount of the sliding contact edge from the inner ring side slinger inner surface corresponds to the axial tightening margin related to the lip tip of the sub seal lip. By forming such an allowance, the lip tip of the secondary seal lip is in the radial direction with the sliding contact edge (not the tip) as the contact start side with respect to the inner surface of the inner ring side slinger. Abutting in an elastic bending deformation while forming an annular belt-like sliding contact surface on the inner peripheral surface.

  In this state, when the centrifugal force accompanying the rotation of the outer ring acts, the secondary seal lip is elastically deformed so as to fall outward in the radial direction, that is, to the axial base surface side, and the amount of the tilt increases as the acting centrifugal force increases. . Considering the above-mentioned non-deformation state, the axial extension amount (tightening margin) from the inner ring side slinger inner surface of the sliding contact edge decreases as the acting centrifugal force increases. Along with this, the radial inner circumferential surface of the lip tip part is turned up in the radial direction from the opposite side while maintaining the contact position of the sliding contact edge substantially constant, and is formed in an annular band shape formed on the inner ring side slinger. As the centrifugal force increases, the sliding width of the sliding contact surface decreases toward the sliding contact edge.

  As a result, the sealability of the bearing and the self-adjusting function of the rotational torque according to the rotational speed can be further enhanced. That is, the sliding contact surface of the secondary seal lip is formed in an annular belt shape, and as the rotational speed of the bearing increases, the width of the sliding contact surface decreases in the radial direction due to the centrifugal force, so sliding friction can be effectively reduced. It is possible to prevent an increase in bearing torque during high-speed rotation. Further, the secondary seal lip of this form can maintain the sliding contact state only by reducing the width of the sliding contact surface even if the centrifugal force is increased to some extent, and the secondary seal lip is less likely to be lifted from the inner ring side slinger. In addition, the ring-shaped sliding contact surface is formed while elastically bending and deforming in such a way that it does not hit the surface in the normal direction of the slinger inner surface from the tip side but hits the line from the sliding contact edge. Even if the width of the surface is somewhat reduced, the sealing performance is not easily lost.

  On the other hand, when the outer ring rotational speed is reduced and the axial tightening margin is increased, the width of the slidable contact surface formed by the lip tip of the sub seal lip is increased, and the sealing performance is improved. Also, the branch seal lip forms the aforementioned annular groove between the lip tip of the sub seal lip and functions as a limiter that limits the increase in the width of the sliding contact surface, thereby suppressing the occurrence of stick slip. To do. Since the tip of the lip and the branch seal lip form a kind of two-stage seal in the radial direction, for example, even when running while submerging in a river, the water that fills the surroundings is the bearing. It is possible to prevent the infiltration into the inside very effectively.

  The secondary seal lip has a lip length L defined as a dimension from the rising start position from the axial base surface to the slidable contact edge in the generatrix direction of the inner peripheral surface in the radial direction as a radial direction dimension of the crossing surface with the axial base surface. It is desirable that the thickness is adjusted to be larger than the specified lip base end thickness θ. As a result, when centrifugal force is applied, the elastic deformation of the collapsed form of the secondary seal lip toward the axial base surface can proceed smoothly, and the sealing performance and the self-adjusting function of the rotational torque according to the bearing rotational speed Can be made more obvious.

  The front end surface of the sub seal lip can be a flat surface. As a result, the secondary seal lip can sharpen the sliding contact edge formed at the intersection of the radially inner circumferential surface and the tip surface while maintaining an appropriate rigidity, and can enhance the effect of improving the sealing performance by line contact. it can.

  The lip tip of the sub-seal lip can be shaped to taper at an acute angle in the cross section including the bearing rotation axis. By making the tip of the lip taper like this, the tip of the sub-seal lip can bend well and the adhesion to the inner ring side slinger can be improved.

  Further, the entire sub seal lip can be formed in a wedge shape that continuously reduces the lip thickness from the rising base end side to the sliding contact side tip in the cross section including the bearing rotation axis. . As a result, the lip thickness at the base end of the secondary seal lip can be secured above a certain level, the secondary seal lip can be prevented from reversing in the radial direction during assembly, and the tip of the lip is tapered. The above effects can be achieved at the same time. In this case, the sub-seal lip may have a shape that is curved in advance so that the whole or the lip tip bulges toward the radially inner circumferential surface that is in contact with the inner ring side slinger. However, from the viewpoint of ensuring a large seal tightening margin, in the cross section including the bearing rotation axis, the acute angle crossing angle between the outer peripheral line indicating the radial inner peripheral surface and the axial base surface is the same as the outer line indicating the outer peripheral surface. It is desirable that all of the outlines in the non-deformed state are linear so as to be smaller than the acute angle crossing angle with the axial base surface.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of a bearing to which a bearing sealing device of the present invention is applied. The bearing 1 is for rotating and supporting an automobile idler pulley, and is configured as a double row deep groove ball bearing (radial bearing) used so that the inner ring 3 is non-rotating and the outer ring 4 is rotating. Yes. The balls 5 and 5 forming the rolling elements are arranged in the rolling element arrangement space 15 formed between the inner ring 3 and the outer ring 4 while the circumferential arrangement interval is regulated by the cages 6 and 6 in each row. Yes. A pulley 20 is concentrically fitted on the outer peripheral surface of the outer ring 4.

  The bearing 1 is provided with bearing sealing devices 7 and 7 in annular openings 15 a and 15 a that respectively appear at both ends in the axial direction of the rolling element arrangement space 15. The bearing sealing devices 7 and 7 on either side have exactly the same configuration, and the main parts thereof include an inner ring side slinger 10 and a sliding seal portion 8.

  FIG. 2 is an enlarged cross-sectional view showing details of one of the bearing sealing devices 7, and the inner ring side slinger 10 has an annular opening 15 a in the rolling element arrangement space 15 formed between the inner and outer rings 3 and 4. Is arranged in such a manner that the inner peripheral edge portion in the radial direction is fitted to the end portion in the axial direction of the inner ring 3 so as not to be relatively rotatable. Specifically, the inner ring side slinger 10 has an annular main body plate 10m disposed concentrically with the inner ring 3 so that the plate thickness direction coincides with the axial direction, and the inner ring side slinger 10 extends in the axial direction from the inner periphery of the opening of the main body plate 10m. And a cylindrical portion 10f integrally formed so as to protrude in the direction. A midway section portion in the radial direction of the main body plate 10m bulges inward in the axial direction from both end section portions, and is an annular reinforcing bulge portion 10d having a flat inner surface 10a. An annular inner ring side step 42 is formed on the outer peripheral edge of the axial end surface of the inner ring 3. The cylindrical portion 10 f of the inner ring side slinger 10 is press-fitted and fitted to the inner peripheral surface 42 a of the inner ring side stepped portion 42.

  Next, the sliding seal portion 8 is disposed opposite to the inner ring side slinger 10 so as to form an axial seal gap 17 on the inner side in the axial direction. The outer peripheral edge in the radial direction is fitted to the axial direction end of the outer ring 4 so as not to be relatively rotatable, and the main seal lip 9 made of an elastic polymer material slidably in contact with the outer side of the axial end of the inner ring 3 on the inner peripheral edge side in the radial direction. Is formed. Further, a surface opposite to the inner ring side slinger 10 is used as an axial base surface 8b, and a secondary seal lip made of an elastic polymer material so as to rise obliquely outward in the radial direction while traversing the axial seal gap 17 from the axial base surface 8b. 94 is formed, and the tip of the sub seal lip 94 is in sliding contact with the inner surface 10a in the axial direction of the inner ring side slinger 10 (which forms the inner surface of the reinforcing bulging portion 10d described above).

  Specifically, the sliding seal portion 8 includes a seal core 81 arranged so that the plate thickness direction coincides with the axial direction, and an elastic polymer material covering a plate surface outside the axial direction of the seal core 81 And a seal main body 8M. The main seal lip 9 is integrally formed with the seal body 8M so as to extend inward in the radial direction from the radial inner peripheral edge of the seal core 81. The sub seal lip 94 is integrally formed with the seal body 8M in such a manner that the outer surface in the axial direction of the seal body 8M is an axial base surface 8b.

  The seal core 81 is integrally formed with an annular main body plate 81m arranged so that the plate thickness direction coincides with the axial direction, and protruding inward in the axial direction from the outer peripheral edge of the main body plate 81m. It has a cylindrical wall portion 81a and a flange portion 81b extending radially outward from the axial end edge of the cylindrical wall portion 81a. The outer peripheral edge portion of the seal body 8M forms an annular fitting lip 8e having a rectangular cross section so as to surround the cylindrical wall portion 81a and the flange portion 81b. On the other hand, a reinforcing bent portion 81c is formed on the inner peripheral side of the seal core 81 so as to be bent obliquely inward in the axial direction. The seal body 8M wraps around the reinforcing bent portion 81c in the radial direction. A main seal lip 9 is formed extending inward.

  The inner peripheral edge portion of the end surface in the axial direction of the outer ring 4 is notched in a stepped shape in the circumferential direction, and an annular outer ring side notch portion 41 is formed. The fitting lip 8e is press-fitted and fitted so as to be in close contact with the bottom surface 41a and the inner peripheral surface 41b of the outer ring side cutout 41. In addition, a retaining rib 41r is formed to protrude in the circumferential direction at an end portion in the axial direction on the open side of the inner peripheral surface 41b of the outer ring side cutout portion 41, and the fitting lip 8e elastically moves the retaining rib 41r. It gets over and is fitted in the outer ring side cutout 41.

  The main seal lip 9 has a base 91 extending radially outward from the seal body 8M and an inner lip 92 extending axially inward from the base 91. The inner lip 92 extends from the base 91 on the radially inner side toward the bottom surface 42b of the inner ring side stepped portion 42 and slidably contacts the bottom surface 42b, and the base 91 on the radially outer side of the inner slidable lip 92a. The inner auxiliary lip 92b extends from the base 91 on the radially outer side of the inner auxiliary lip 92b to the inner side in the axial direction. The outer lip 93 has a first outer lip 93a extending outward in the axial direction at substantially the same position as the radial direction of the inner sliding lip 92a in the base 91, and a radial position of the inner auxiliary lip 92b in the base 91. A second outer lip 93b extending outward in the axial direction.

  At the beginning of use, the inner lip 92 is configured such that only the inner sliding lip 92a is in sliding contact with the bottom surface 42b of the inner ring side step portion 42, and the inner auxiliary lip 92b is not in sliding contact with the bottom surface 42b of the inner ring side step portion 42. Yes. The inner auxiliary lip 92b comes into slidable contact with the bottom surface 42b of the inner ring side stepped portion 42 when the inner slidable contact lip 92a wears a certain amount after the service of the bearing 1 is started. The axial lip 92 c forms a labyrinth seal with the outer peripheral surface 3 a of the inner ring 3. In order to perform sliding lubrication of each seal lip, grease is attached to the bottom surface 42b of the inner ring side stepped portion 42 and the inner surface 10a of the inner ring side slinger 10.

  Next, as shown in FIG. 4, on the radially inner circumferential surface of the sub seal lip 94, an annular branch seal lip 95 is formed projecting toward the inner surface of the inner ring side slinger 10 at a midway position in the radial direction. . When the outer ring 4 is not rotated, the tip of the branch seal lip 95 is in sliding contact with the inner surface of the inner ring side slinger 10, while the tip of the lip located on the tip side of the sub seal lip 94 in the radial direction from the branch seal lip 95. The radial inner peripheral surface of the portion 94t is configured to reduce the distance from the inner surface of the inner ring side slinger 10 toward the lip tip. In FIG. 4, a lip tip 94 t of the sub seal lip 94 is formed with a gap ε that forms a labyrinth seal between the radially inner peripheral tip of the lip tip 94 t and the inner ring-side slinger 10. .

  The lip tip 94t of the secondary seal lip 94 is already in non-contact with the inner ring side slinger 10 when the outer ring 4 is not rotated, and even when the outer ring 4 is rotated, as shown by a broken line in FIG. In addition, because of the centrifugal force, the secondary seal lip 94 falls and deforms in a direction away from the axial base surface 8b side, that is, the inner ring side slinger 10, so that the lip tip 94t does not slide with the inner ring side slinger 10. . On the other hand, an annular branch seal lip 95 is formed to project toward the inner surface of the inner ring side slinger 10 on the radially inner peripheral surface of the sub seal lip 94, and the tip of the branch seal lip 95 is linear with respect to the inner ring side slinger 10. The sliding contact surface is formed. As the rotational speed of the outer ring 4 decreases, the axial margin of the branch seal lip 95 increases. However, as shown by the solid line in FIG. 4, the lip end portion 94 t of the sub seal lip 94 is not connected to the inner ring side slinger 10. Since the contact state is maintained, the lip sliding contact area is hardly excessive, and the occurrence of stick slip can be effectively suppressed.

  Further, even when water droplets or the like break through the branch seal lip 95 and enter the main seal lip 9 (FIG. 2), the outer ring 4 is in a rotating state, and the centrifugal force reduces the axial direction tightening allowance. The water droplets can be quickly discharged out of the sub seal lip 94 from the seal lip 95 through the non-contact lip tip portion 94t.

  Next, FIG. 4 shows the radial inner peripheral surface tip edge of the lip distal end portion 94t of the sub seal lip 94 with the radial inner peripheral surface and the radial direction of the branch seal lip 95 in a state where the outer ring 4 is not rotated. This is an example in which an annular groove 99 formed by the outer peripheral surface is separated from the inner surface of the inner ring side slinger 10 together with the branch seal lip 95. The sub seal lip 94 has a slidable contact edge 94e formed at the intersection of the tip surface 94c of the lip tip portion 94t and the radially inner circumferential surface 94a. The lip tip position of the sub seal lip 94 in a virtual non-deformed state in which the inner ring side slinger 10 is omitted is shown by a one-dot chain line in FIG. In the actual assembled state of the bearing, the secondary seal lip 94 is always elastically deformed by the inner ring side slinger 10 when the bearing is not rotating. However, if the internal ring side slinger 10 is removed, the secondary seal lip 94 is not removed. The shape in the deformed state can be confirmed.

  The sliding contact edge 94e is located outside by a certain distance in the axial direction from the position of the inner surface 10a of the inner ring side slinger 10 in the non-deformed state (and the bearing non-rotating state). The axial extension amount of the sliding contact edge 94e from the inner ring side slinger 10 inner surface when considered in the non-deformed state is the non-rotating state (and negative pressure) of the outer ring 4 at the lip tip portion 94t of the sub seal lip 94. In the axial direction) is given. The lip tip portion 94t of the sub seal lip 94 has an annular belt-like slidable contact surface 94a ′ on the radially inner circumferential surface 94a with the slidable contact edge 94e as a contact start side with respect to the inner surface 10a of the inner ring side slinger 10. And abut in a form of elastic bending deformation. On the other hand, the front end surface 94c of the lip front end portion 94t does not contact the inner ring side slinger 10. The front end surface 94c is a flat surface, and the sliding contact edge 94e is sharpened while maintaining an appropriate rigidity, thereby contributing to an improvement in sealing performance due to line contact.

  In this state, when the centrifugal force accompanying the rotation of the outer ring 4 acts, as shown in FIG. 6, the secondary seal lip 94 is elastic so as to fall outward in the radial direction, that is, to the axial base surface 8b (FIG. 3) side. As the centrifugal force acting is increased, the amount of tilting increases, and the axial direction allowance δ decreases as the amount of tilting increases. Then, the radial inner peripheral surface 94a of the lip tip 94t is turned up in the radial direction from the opposite side while maintaining the contact position of the sliding contact edge 94e substantially constant, and the ring formed on the inner ring side slinger 10 In the belt-like sliding contact surface 94a ′, the radial width W decreases toward the sliding contact edge 94e as the centrifugal force increases. That is, when the radial width of the sliding contact surface 94a ′ when the outer ring 4 is not rotating is W0, and the radial width when the outer ring 4 is rotated and centrifugal force is applied is W1, W1 <W0. Become. Thereby, the sub seal lip 94 embodies the function of self-adjusting the sealing performance and the rotational torque of the bearing according to the rotational speed of the outer ring 4. That is, the sliding contact surface 94a ′ of the secondary seal lip 94 is formed in an annular belt shape, and the width of the sliding contact surface 94a ′ is reduced in the radial direction by the centrifugal force as the rotational speed of the outer ring 4 increases. Can be effectively reduced, and an increase in bearing torque during high-speed rotation can be prevented.

  Even if the centrifugal force is increased to some extent, the secondary seal lip 94 can maintain the sliding contact state only by reducing the width of the sliding contact surface 94 a ′, and the secondary seal lip 94 is less likely to be lifted from the inner ring side slinger 10. In addition, as shown in FIG. 5, the surface is not contacted from the tip side in the normal direction of the slinger inner surface, but is contacted from the sliding contact edge 94e at the boundary between the tip surface 94c and the radial inner peripheral surface 94a. Since the ring-shaped slidable contact surface 94a ′ is formed while being elastically bent and deformed, even if the width of the slidable contact surface 94a ′ is somewhat reduced by centrifugal force, the sealing performance is not easily impaired.

  On the other hand, when the rotational speed of the outer ring 4 decreases and the centrifugal force acting on the sub seal lip 94 decreases, the axial clamping margin of the lip tip 94t increases, the width of the slidable contact surface 94a ′ increases, and the sealing performance increases. improves. Further, the branch seal lip 95 functions as a limiter that limits the increase in the width of the sliding contact surface by forming the aforementioned annular groove 99 between the branch seal lip 95 and the lip tip portion 94t of the sub seal lip 94. Suppresses the occurrence of The lip tip portion 94t and the branch seal lip 95 form a kind of two-stage seal in the radial direction. For example, even when the lip tip 94t and the branch seal lip 95 travel while being submerged in a river, It is possible to prevent the infiltration into the inside very effectively.

  Next, when the rolling element arrangement space 15 becomes negative pressure or when δ becomes large by setting the tightening allowance, as shown by the broken line in FIG. It is elastically deformed (in a direction to be pressed against the inner ring side slinger 10). In this case, the tightening margin of the branch seal lip 95 increases, but the lip tip portion 94t of the sub seal lip 94 has a negative effect that the lip tip portion 94t acts on the inner surface of the inner ring side slinger 10 with the branch seal lip 95 as a fulcrum. As the pressure increases, the lip tip 94t swings away from the inner surface of the inner ring side slinger 10. As a result, the axial tightening margin of the lip tip portion 94t of the sub seal lip 94 during the negative pressure action is reduced by the swinging, and stick slip is less likely to occur.

Sectional drawing which shows an example of the bearing for idler pulleys which applied the sealing device for bearings of this invention. Sectional drawing which expands and shows the sealing device part for bearings of FIG. Sectional drawing which expands and shows the sub seal lip of the sealing device for bearings of FIG. Sectional drawing which expands further and shows the lip front-end | tip part vicinity of a sub seal lip. Sectional drawing which shows the modification which makes the lip front-end | tip part of a sub seal lip contact the inner ring | wheel side slinger. FIG. 6 is an operation explanatory view of a sub seal lip in the configuration of FIG. 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bearing 3 Inner ring 4 Outer ring 7 Bearing sealing device 8 Sliding seal part 8b Axial base surface 9 Main seal lip 94 Sub seal lip 94a Radial inner surface 94a 'Sliding surface 94e Sliding edge 94t Lip tip 95 Branch seal Lip 10 Inner ring side slinger 15 Rolling element arrangement space 15a Annular opening 17 Axial seal gap

Claims (5)

A radial bearing sealing device used in outer ring rotation,
An inner ring side slinger that is arranged in such a manner as to block the annular opening of the rolling element arrangement space formed between the inner and outer rings in the axial direction, and the radial inner peripheral edge is fitted to the axial end of the inner ring in a relatively non-rotatable manner. When,
The inner ring side slinger is opposed to the inner ring in the form of forming an axial seal gap on the inner side in the axial direction. The outer peripheral edge of the radial direction is fitted to the axial end of the outer ring in a relatively non-rotatable manner, and the inner peripheral side of the radial direction. A main seal lip made of an elastic polymer material that is in sliding contact with the outer end of the inner ring in the axial direction is formed, and the surface facing the inner ring side slinger is an axial base surface, and extends in the axial direction from the axial base surface. A sliding seal portion formed with a secondary seal lip to be ejected,
On the radially inner circumferential surface of the sub seal lip, an annular branch seal lip is formed projecting toward the inner surface of the inner ring side slinger at a midway position in the radial direction, and the inner ring is in a non-rotating state. The distal end of the branch seal lip is in sliding contact with the inner surface of the side slinger, while the radially inner peripheral surface of the lip distal end located on the distal end side in the radial direction with respect to the branch seal lip of the sub seal lip is closer to the lip tip. A bearing sealing device characterized by being configured to reduce the distance from the inner surface of the inner ring side slinger.   A gap forming a labyrinth seal is formed between a leading edge of a radially inner peripheral surface of the lip tip of the sub seal lip and an inner surface of the inner ring side slinger when the outer ring is not rotated. The bearing sealing device according to 1.   In the state where the outer ring is not rotated, the radial inner peripheral surface tip edge of the lip tip portion of the sub seal lip is formed by the radial inner peripheral surface and the radial outer peripheral surface of the branch seal lip. The bearing sealing device according to claim 1, wherein the bearing sealing device is slidably contacted with the inner surface of the inner ring side slinger together with the branch seal lip with a groove therebetween.   The sub seal lip is elastically deformed inward in the radial direction due to the negative pressure in the rolling element arrangement space, and the lip tip portion is rocked with the branch seal lip as a fulcrum with respect to the inner surface of the inner ring side slinger. 4. The bearing sealing device according to claim 3, wherein the bearing sealing device is moved and moved in accordance with the negative pressure in a moving form.   The secondary seal lip has a sliding contact edge formed at the tip of the lip, and in a virtually undeformed state in which the inner ring side slinger is omitted, the sliding contact edge is a fixed distance in the axial direction from the inner surface position of the inner ring side slinger. An annular belt-like slidable contact is formed on the radially inner circumferential surface so that the lip tip is on the contact start side with respect to the inner surface of the inner ring side slinger. A radial contact width of the ring-shaped sliding contact surface formed between the inner lip side slinger and the lip tip is formed by elastic bending deformation while forming a surface, as the centrifugal force increases. The bearing sealing device according to claim 3, wherein the bearing sealing device is contracted toward the sliding contact edge.

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