Title of Invention: Rolling Bearing
Technical field
[0001]
　The present invention relates to rolling bearings, and more particularly to rolling bearings used in air turbines.
Background technology
[0002]
　As a conventional rolling bearing for a dental air turbine, one using a seal member suitable for ultra-high speed rotation is known (see, for example, Patent Document 1). The rolling bearing includes an outer ring, an inner ring, a plurality of balls arranged between the outer ring and the inner ring, a retainer for rotatably holding the plurality of balls, and a cage provided between the outer ring and the inner ring. An annular sealing member and a retaining ring for attaching the sealing member to the outer ring are provided, and the sealing member is composed only of an elastic material without a core metal.
prior art documents
patent literature
[0003]
Patent Document 1: Japanese Patent Application Laid-Open No. 2017-211076
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0004]
　However, in the rolling bearing disclosed in Patent Document 1, the seal member is fixed to the groove of the outer ring by the pressing force of the retaining ring in the thrust direction. Stronger fixation may be required. In such a case, if fixing means in the radial direction can be provided, the seal can be fixed more firmly.
[0005]
　SUMMARY OF THE INVENTION The present invention has been made in view of the problems described above, and an object of the present invention is to provide a rolling bearing in which the binding force of the seal member is stronger.
[0006]
　The above objects of the present invention are achieved by the following configurations.
(1) An outer ring having an outer ring raceway surface on its inner peripheral surface, an inner ring having an inner ring raceway surface on its outer peripheral surface, and a plurality of rolling elements arranged to be able to roll between the outer ring raceway surface and the inner ring raceway surface. and a seal member fixed by a snap ring to a seal mounting groove formed in the axial end of the outer ring and sealing the axial end of the bearing inner space between the outer ring and the inner ring. In the bearing, the outer diameter of the seal member is larger than the outer diameter of the retaining ring in the seal mounting groove, and the radially outer end portion of the seal member is located between the inner peripheral surface of the seal mounting groove and the Rolling bearing sandwiched between the outer peripheral surface of the retaining ring.
(2) The seal mounting groove is provided on a groove bottom surface with which the outer peripheral surface of the seal member is in contact, and axially outside of the groove bottom surface, connects the groove bottom surface and the inner peripheral surface of the outer ring, and connects the groove bottom surface with the inner peripheral surface of the outer ring. and a groove inner surface provided axially inside the groove bottom surface with which the axial inner surface of the seal member contacts.
(3) The rolling bearing according to (2), wherein the seal mounting groove has a step portion provided at a boundary portion between the groove bottom surface and the groove inner side surface.
(4) The rolling bearing according to any one of (1) to (3), which is for a dental air turbine.
Effect of the invention
[0007]
　According to the present invention, since the radially outer end of the seal member is sandwiched between the inner peripheral surface of the seal mounting groove and the outer peripheral surface of the retaining ring, it is possible to generate a restraining force in the radial direction of the seal member. can. Thereby, the binding force of the sealing member can be further increased.
Brief description of the drawing
[0008]
1 is an enlarged cross-sectional view of a head portion of a dental air turbine handpiece employing a first embodiment of a rolling bearing according to the present invention; FIG.
2 is a cross-sectional view of the rolling bearing shown in FIG. 1; FIG.
3 is an enlarged cross-sectional view of the periphery of the retaining ring shown in FIG. 2;
4 is an enlarged sectional view of the state before the sealing member shown in FIG. 2 is attached; FIG.
5 is a view for explaining attachment of the snap ring and the sealing member shown in FIG. 2; FIG.
[Fig. 6] Fig. 6 is an enlarged cross-sectional view of a main part for explaining a first modification of the rolling bearing of the first embodiment. [Fig.
7] Fig. 7 is an enlarged cross-sectional view of a main part for explaining a second modification of the rolling bearing of the first embodiment. [Fig.
8] Fig. 8 is an enlarged cross-sectional view of a main part explaining a second embodiment of a rolling bearing according to the present invention. [Fig.
9 is an enlarged sectional view of the state before the sealing member shown in FIG. 8 is attached; FIG.
MODE FOR CARRYING OUT THE INVENTION
[0009]
　Hereinafter, each embodiment of the rolling bearing according to the present invention will be described in detail based on the drawings.
[0010]
(First Embodiment)
　First, a rolling bearing according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 7. FIG.
[0011]
　The rolling bearing 10 of this embodiment is employed in the bearing unit 120 of the head portion 110 of the dental air turbine handpiece 100 . The bearing unit 120 includes a rotary shaft 121 to which a tool (for example, a dental treatment tool) can be attached at one end, turbine blades 122 integrally fixed to the rotary shaft 121 and rotated by receiving compressed air, and a housing 130. and a pair of rolling bearings 10 that rotatably support the rotating shaft 121 .
[0012]
　Rolling bearing 10 is supported by housing 130 via rubber rings 123 fitted in annular recesses 131 and 132 of housing 130 . Further, the rolling bearing 10 on one side (lower side in FIG. 1) is urged by the spring washer 124 toward the rolling bearing 10 on the other side (upper side in FIG. 1).
[0013]
　As shown in FIG. 2, the rolling bearing 10 includes an outer ring 11 having an outer ring raceway surface 11a on its inner peripheral surface, an inner ring 12 having an inner ring raceway surface 12a on its outer peripheral surface, and an outer ring raceway surface 11a and an inner ring raceway surface 12a. A plurality of balls (rolling elements) 13 arranged to be able to roll therebetween, a retainer 14 holding the plurality of balls 13 at substantially equal intervals in the circumferential direction, and a seal formed at one axial end of the outer ring 11 . and a seal member 20 fixed to the mounting groove 15 by a retaining ring 30 and sealing one axial end of the bearing inner space 10 a between the outer ring 11 and the inner ring 12 . Note that the rolling bearing 10 is not limited to the illustrated deep groove ball bearing, and may be an angular ball bearing.
[0014]
　The retainer 14 is a crown-shaped retainer, and an annular rim portion 14a is disposed on the upstream side (right side in FIG. 2) of the balls 13 in the supply direction of the compressed air. In addition, the arrow in FIG. 2 has shown the direction through which compressed air flows. Moreover, the retainer is not limited to a crown-type retainer.
[0015]
　The seal member 20 is an annular member, and is composed only of an elastic member without a metal core. The seal member 20 is arranged downstream of the ball 13 in the compressed air supply direction (left side in FIG. 2).
[0016]
　As shown in FIGS. 2 and 4 , the sealing member 20 includes a base portion 21 that extends in the radial direction, and an outer peripheral surface of the inner ring 12 that extends obliquely radially inward and axially outward from the radial inner end of the base portion 21 . and a lip portion 22 that contacts the . Further, as shown in FIG. 4, the base portion 21 of the seal member 20 alone before being attached to the outer ring 11 is not formed with a step that matches the shape of a step portion 15d to be described later. It has equal width to the ends.
[0017]
　The outer peripheral portion of the seal member 20 is fixed by a snap ring 30 to a seal mounting groove 15 formed at one axial end (the left end in FIG. 2) of the inner peripheral surface of the outer ring 11 . The retaining ring 30 is a ring-shaped member with a rectangular cross-section, which is partially cut off. Also, the outer diameter of the seal member 20 is set larger than the outer diameter of the retaining ring 30 in the seal mounting groove 15 .
[0018]
　Examples of materials for the sealing member 20 include water-resistant acrylic rubber with a Shore A hardness (JIS K 6253) of 60 to 90, general water-resistant fluororubber with a Shore A hardness of 60 to 90, and the like. By using the above materials, the sealing member 20 can obtain appropriate elastic characteristics, and can improve durability and wear resistance.
[0019]
　A tapered surface 12b with which the lip portion 22 of the seal member 20 contacts is formed at one axial end portion (the left end portion in FIG. 2) of the outer peripheral surface of the inner ring 12. As shown in FIG. The tapered surface 12b is formed so as to gradually decrease in diameter toward the outer side in the axial direction.
[0020]
　As shown in FIG. 3, the seal mounting groove 15 is provided on a groove bottom surface 15a with which the outer peripheral surface of the seal member 20 contacts and on the axially outer side of the groove bottom surface 15a. A tapered surface 15b with which the retaining ring 30 contacts, a groove inner side surface 15c provided axially inside the groove bottom surface 15a and with which the axial inner side surface of the seal member 20 contacts, the groove bottom surface 15a and the groove inner side surface and a stepped portion 15d provided at a boundary portion with 15c. The tapered surface 15b is formed so as to gradually increase in diameter toward the inner side in the axial direction.
[0021]
　Then, as shown in FIG. 5, the seal member 20 is fitted into the seal mounting groove 15, and the diameter-reduced retaining ring 30 is fitted into the seal mounting groove 15, whereby the diameter of the retaining ring 30 is expanded. The outer peripheral edge of the axially outer side surface of the ring 30 contacts the tapered surface 15 b of the seal mounting groove 15 . As a result, the force that tends to spread radially outward of the retaining ring 30 is converted by the tapered surface 15b into a force (pressing force in the thrust direction) that presses the seal member 20 axially inward, and the base portion 21 of the seal member 20 is , is sandwiched between the retaining ring 30 and the stepped portion 15d (including the groove inner side surface 15c).
[0022]
　Therefore, part of the radially outer end portion of the seal member 20 is elastically deformed in the direction of the tapered surface 15b of the seal mounting groove 15, and protrudes from the inner peripheral surface of the seal mounting groove 15 (in this embodiment, a groove). It is sandwiched between the bottom surface 15 a ) and the outer peripheral surface of the retaining ring 30 . Reference numeral 21 a in FIG. 3 denotes a portion sandwiched between the inner peripheral surface of the seal mounting groove 15 and the outer peripheral surface of the retaining ring 30 at the radially outer end portion of the seal member 20 . The inner peripheral surface of the seal mounting groove 15 sandwiching the radial outer end of the seal member 20 may include a tapered surface 15b.
[0023]
　As described above, a portion of the radially outer end portion of the seal member 20 (the portion indicated by reference numeral 21a) is sandwiched between the inner peripheral surface of the seal mounting groove 15 and the outer peripheral surface of the retaining ring 30, so that the seal member 20 is radial direction restraint force is generated. Further, since the stepped portion 15d is formed in the seal mounting groove 15, the amount of deformation of the base portion 21 of the seal member 20 is larger than in the conventional case, so that the restraining force of the seal member 20 in the thrust direction is increased. That is, in the present embodiment, a radial restraining force of the seal member 20 is generated, which is not available in the conventional technique, and a thrust restraint force of the seal member 20 is increased more than in the conventional technique.
[0024]
　In addition, a space S is formed between the inner peripheral surface of the seal mounting groove 15 and the outer peripheral surface of the retaining ring 30 in consideration of the dimensional tolerances of the seal mounting groove 15, the sealing member 20, the retaining ring 30, and the like. is preferred.
[0025]
　Furthermore, in this embodiment, when the seal member 20 and the retaining ring 30 are attached to the seal mounting groove 15, the radially inner end portion 15e of the stepped portion 15d is positioned between the outer peripheral surface of the retaining ring 30 and the inner peripheral surface of the outer ring 11. It is preferable to be provided so as to be radially inward of a radial midpoint P between the . As a result, the area of ​​the stepped portion 15 d that presses the seal member 20 in the seal mounting groove 15 increases, so that the radial direction of the seal member 20 is increased between the inner peripheral surface of the seal mounting groove 15 and the outer peripheral surface of the retaining ring 30 . A portion of the outer end portion (the portion indicated by reference numeral 21a) is likely to be pinched.
[0026]
　As described above, according to the rolling bearing 10 of the present embodiment, the radial outer end portion of the seal member 20 is sandwiched between the inner peripheral surface of the seal mounting groove 15 and the outer peripheral surface of the retaining ring 30. , a radial restraining force of the sealing member 20 can be generated. Thereby, the binding force of the seal member 20 can be further increased.
[0027]
　Further, according to the rolling bearing 10 of the present embodiment, since the seal mounting groove 15 has the stepped portion 15d provided at the boundary portion between the groove bottom surface 15a and the groove inner side surface 15c, when the stepped portion 15d is not formed, , the amount of deformation of the base portion 21 of the seal member 20 is increased, and the restraining force of the seal member 20 in the thrust direction can be increased. Thereby, the binding force of the seal member 20 can be further increased.
[0028]
　Further, as a first modified example of the present embodiment, as shown in FIG. 6, the step portion 15d of the seal mounting groove 15 is not limited to one step, and may be two or more steps.
[0029]
　As a second modification of the present embodiment, as shown in FIG. 7, the stepped portion 15d of the seal mounting groove 15 is not limited to a rectangular cross section, and may have a convex circular arc cross section. It may be polygonal.
[0030]
(Second Embodiment)
　Next, a second embodiment of the rolling bearing 10 according to the present invention will be described with reference to FIGS. 8 and 9. FIG. The same or equivalent parts as those of the first embodiment are denoted by the same reference numerals in the drawings, and the description thereof will be omitted or simplified.
[0031]
　In this embodiment, as shown in FIGS. 8 and 9 , the sealing member 20 may have a metal core 25 on the base 21 . The cored bar 25 is provided integrally with the inner side of the base portion 21 in the axial direction, and a part of the inner side surface thereof in the axial direction is exposed to the ball 13 side. Further, the cored bar 25 is arranged radially inward of the radially inner end portion 15e of the stepped portion 15d. Further, the radially outer end portion of the axially inner side surface of the cored bar 25 is in contact with the groove inner side surface 15 c of the seal mounting groove 15 .
[0032]
　Further, according to this embodiment, the volume of the core metal 25 required for fixing the seal member can be reduced, so the friction torque of the seal member 20 can be reduced, and the manufacturing cost of the seal member 20 can be reduced. can be reduced.
　Other configurations and effects are the same as those of the first embodiment.
[0033]
　It should be noted that the present invention is not limited to the examples illustrated in the above embodiments, and can be modified as appropriate without departing from the gist of the present invention.
　For example, the stepped portion of the seal mounting groove may be formed to the same radial position as the inner peripheral surface of the outer ring. That is, in this case, the groove inner side surface is not formed.
　Moreover, the retaining ring is not limited to a rectangular cross-section, and may have a circular cross-section.
　Alternatively, the retaining ring may be formed with a tapered surface, and the seal mounting groove may be formed with a rectangular cross-section so that the tapered surface of the retaining ring is brought into contact with the corners of the seal mounting groove with a rectangular cross-section.
[0034]
　This application is based on a Japanese patent application (Japanese Patent Application No. 2019-063257) filed on March 28, 2019, the content of which is incorporated herein by reference.
Code explanation
[0035]
　　10 Rolling bearing
　　10a Bearing inner space
　　11 Outer ring
　　11a Outer ring raceway surface
　　12 Inner ring
　　12a Inner ring raceway surface
　　13 Ball (rolling element)
　　14 Cage
　　15 Seal mounting groove
　　15a Groove bottom surface
　　15b Taper surface
　　15c Groove inner side surface
　　15d Stepped portion
　　15e Diameter of stepped portion Direction inner end portion
　　20 Seal member
　　21 Base
　　portion 21a Portion 22 sandwiched between the seal mounting groove and the retaining ring
　　Lip portion
　　30 Retaining ring
The scope of the claims
[Claim 1]
　an outer ring having an outer
　ring raceway surface on its inner peripheral surface; an inner ring having an inner ring raceway surface on its outer peripheral surface
　; a plurality of rolling elements arranged to roll between the outer ring raceway surface and the inner ring raceway surface
　; a seal member fixed by a snap ring to a seal mounting groove formed in an axial end of an outer ring and sealing an axial end of a space inside the bearing between the outer ring and the inner ring. The outer diameter of the seal member
　is larger than the outer diameter of the retaining ring in the seal mounting groove, and the
　radially outer end portion of the sealing member extends between the inner peripheral surface of the seal mounting groove and the retaining ring. Rolling bearing sandwiched between the outer peripheral surface.
[Claim 2]
　The seal mounting groove is provided on
　a groove bottom surface with which the outer peripheral surface of the seal member contacts and on
　the axially outer side of the groove bottom surface, connects the groove bottom surface and the inner peripheral surface of the outer ring, and is in contact with the retaining ring. 2. The rolling bearing according to claim 1, comprising a tapered surface and a
　groove inner surface provided axially inside said groove bottom surface with which said axial inner surface of said seal member contacts.
[Claim 3]
　3. The rolling bearing according to claim 2, wherein said seal mounting groove has a step portion provided at a boundary portion between said groove bottom surface and said groove inner side surface.
[Claim 4]
　A rolling bearing according to any one of claims 1 to 3, wherein said rolling bearing is for a dental air turbine.