Rolling bearing

Abstract

A rolling bearing (10) is provided with an outer ring (11) having an outer ring raceway surface (11a) on an inner peripheral surface, an inner ring (12) having an inner ring raceway surface (12a) on an outer peripheral surface, a plurality of rolling elements (13) configured to be able to roll between the outer ring raceway surface (11a) and the inner ring raceway surface (12a), and a seal member (20) fixed to a seal mounting groove (15) formed at an axial end portion of the outer ring (11) by a retainer (30) and sealing an axial end portion of a bearing internal space (10a) between the outer ring (11) and the inner ring (12). The seal member (20) has a protruding portion (21a) at a radially outer end portion, an outer diameter of the seal member (20) is larger than an outer diameter of the retainer (30) in the seal mounting groove (15), and the protruding portion of the seal member (20) is sandwiched between an inner peripheral surface of the seal mounting groove (15) and an outer peripheral surface (30a) of the retainer (30).

Description

TECHNICAL FIELD

[0001] The present application relates to a rolling bearing, and particularly to a rolling bearing used in an air turbine. BACKGROUND

[0002] As a conventional rolling bearing for a dental air turbine, there is known a rolling bearing using a seal member suitable for super-high-speed rotation (for example, refer to Patent Literature 1). Moreover, the rolling bearing has an outer ring, an inner ring, a plurality of rolling elements disposed between the outer ring and the inner ring, a cage that rotatably holds the plurality of rolling elements, a circular ring-shaped seal member provided between the outer ring and the inner ring, and a retainer that mounts the seal member to the outer ring. The seal member does not have a core and is composed only of an elastic material so that the seal member is easily opened and closed with the supply and stop of compressed air.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 2017-211076 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] However, in the rolling bearing described in Patent Literature 1 described above, the seal member is fixed to the groove portion of the outer ring by the pressing force in the thrust direction of the retainer. Therefore, in the case where the rolling bearing is used in a state where compressed air for rotating a turbine blade acts on the seal member outward of the bearing, in order to suppress the seal member from coming out, it can be necessary to fix more firmly. In such a case, if a fixing unit in the radial direction can be provided, it is possible to perform more firm fixation of the seal.

[0008] The present application has been achieved in view of the above-described problems, and an object thereof is to provide a rolling bearing that makes the constraint of a seal member more firm.

[0009] MEANS OF SOLVING THE PROBLEM

[0010] The above-described object of the present application is achieved by the following configuration.

[0011] (1) A rolling bearing, wherein:

[0012] an outer ring having an outer ring raceway surface on an inner peripheral surface;

[0013] an inner ring having an inner ring raceway surface on an outer peripheral surface;

[0014] a plurality of rolling elements disposed so as to be able to roll between the outer ring raceway surface and the inner ring raceway surface; and

[0015] a seal member is fixed to a seal mounting groove formed at an axial end portion of the outer ring, and seals an axial end portion of a bearing inner space between the outer ring and the inner ring,

[0016] the seal member has a protruding portion at a radially outer end portion,

[0017] an outer diameter of the seal member is larger than an outer diameter of the retainer in the seal mounting groove.

[0018] (2) The rolling bearing according to (1), wherein

[0019] the seal mounting groove has:

[0020] a groove bottom surface that contacts an outer peripheral surface of the seal member;

[0021] a tapered surface that is provided at an axial outer side of the groove bottom surface, connects the groove bottom surface with an inner peripheral surface of the outer ring, and contacts the retainer; and

[0022] a groove inner side surface that is provided at an axial inner side of the groove bottom surface, and contacts an axial inner side surface of the seal member.

[0023] (3) The rolling bearing according to (2), wherein

[0024] the protruding portion of the seal member is sandwiched between an inner peripheral surface of the seal mounting groove and an outer peripheral surface of the retainer.

[0025] (4) The rolling bearing according to (3), wherein

[0026] a protruding portion is provided at the groove bottom surface of the seal mounting groove, and is radially opposed to the outer peripheral surface of the retainer and located at a position that is axially inward of a distal end of the protruding portion of the seal member.

[0027] (5) The rolling bearing according to any one of (1) to (4),

[0028] the rolling bearing is used for a dental air turbine.

[0029] Effects of Invention

[0030] According to the present application, since a protruding portion is provided at a radially outer end portion of a seal member, a restraining force in a radial direction of the seal member can be generated. Thus, the restraining force of the seal member can be further improved. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1This is an enlarged cross-sectional view of the head of a dental air turbine handpiece employing a rolling bearing according to the first embodiment of the present invention.

[0032] Figure 2 yes Figure 1 The image shows a cross-sectional view of a rolling bearing.

[0033] Figure 3 yes Figure 2 An enlarged sectional view of the periphery of the retaining ring shown.

[0034] Figure 4 yes Figure 2 An enlarged cross-sectional view of the sealing component before installation.

[0035] Figure 5 This is an enlarged cross-sectional view of the periphery of the retaining ring in the second embodiment.

[0036] Figure 6 This is a cross-sectional view showing the stopped state of the rolling bearing according to the third embodiment.

[0037] Figure 7 yes Figure 6 The shown is a cross-sectional view of the sealing component.

[0038] Figure 8 It shows the retaining ring inserted into the outer ring along the entire circumference. Figure 6 A cross-sectional view of line VIII-VIII.

[0039] Symbol Explanation

[0040] 10 Rolling bearings

[0041] 10a Bearing Internal Space

[0042] 11 Outer ring

[0043] 11a Outer ring raceway surface

[0044] 11b Outer inner circumferential surface

[0045] 12 Inner Circle

[0046] 12a Inner ring raceway surface

[0047] 12b Inclined surface

[0048] 13 Ball bearings

[0049] 14. Cage

[0050] 14a Flange

[0051] 15 Sealing mounting groove

[0052] 15a bottom surface of the channel

[0053] 15b cone surface

[0054] 15c groove inner surface

[0055] 15d protrusion

[0056] 20 seal member

[0057] 21 base

[0058] 21a protrusion

[0059] 21b tip end

[0060] 22 lip

[0061] 30 retainer

[0062] 30a outer peripheral surface

[0063] Tm radial length between inner peripheral surface of outer ring and inner peripheral surface of retainer in state where seal member is fixed to groove portion of outer ring by retainer

[0064] An radial length between inner peripheral surface of outer ring and outer peripheral surface of inner ring

[0065] San radial length between inner peripheral surface of retainer and outer peripheral surface of inner ring in state where seal member is fixed to groove portion of outer ring by retainer

[0066] Sct axial thickness of portion of seal member that contacts retainer

[0067] Lss radial length of both axial sides of seal member that are sandwiched by both retainer and groove portion of outer ring

[0068] Thn radial distance between outer peripheral surface of retainer and outer end portion of cone surface of groove portion in state where seal member is fixed to groove portion of outer ring by retainer DETAILED DESCRIPTION

[0069] Hereinafter, each embodiment of the rolling bearing according to the present application will be described in detail based on the drawings.

[0070] (First Embodiment)

[0071] First, with reference to Figure 1-4 , an embodiment of the rolling bearing according to the present application will be described.

[0072] The rolling bearing 10 in this embodiment is, for example, used for a dental air turbine and is used in the bearing unit 120 of the head 110 of the dental air turbine handpiece 100. The bearing unit 120 includes: a rotating shaft 121, on which a tool (e.g., a dental treatment tool) can be mounted; a turbine blade 122 integrally fixed to the rotating shaft 121 and rotated by compressed air; and a pair of rolling bearings 10 that rotatably support the rotating shaft 121 to the housing 130.

[0073] The rolling bearings 10 are supported on the housing 130 by rubber rings 123 mounted in the annular recesses 131 and 132 of the housing 130. Additionally, on one side ( Figure 1 The rolling bearing 10 on the lower side is oriented towards the other side by the spring washer 124. Figure 1 The rolling bearing 10 (on the upper side) applies force.

[0074] like Figure 2 As shown, the rolling bearing 10 includes: an outer ring 11 having an outer ring raceway surface 11a on its inner circumferential surface; an inner ring 12 having an inner ring raceway surface 12a on its outer circumferential surface; a plurality of balls (rolling elements) 13 arranged between the outer ring raceway surface 11a and the inner ring raceway surface 12a for rolling; a cage 14 holding the plurality of balls 13 at approximately equal intervals in the circumferential direction; and a sealing member 20 fixed to one axial end of the inner circumferential surface of the outer ring 11 by a retaining ring 30. Figure 2 The inner ring 12 is fixed to the rotating shaft 121 and rotates together with it. The outer ring 11 is fixed to the housing 130. Furthermore, in the axial direction of the rolling bearing 10, with reference to the outer ring raceway surface 11a and the inner ring raceway surface 12a, the direction closest to the outer ring raceway surface 11a and the inner ring raceway surface 12a is defined as the axial inner side, and the direction away from the outer ring raceway surface 11a and the inner ring raceway surface 12a is defined as the axial outer side. Additionally, the rolling bearing 10 is not limited to the deep groove ball bearing shown in the figure; it can also be an angular contact ball bearing.

[0075] Cage 14 is a crown-type cage, with an annular rim 14a positioned upstream of the compressed air supply direction relative to the balls 13. Figure 2 (On the right side). Additionally... Figure 2 Arrow P in the diagram indicates the direction of compressed air flow. Furthermore, cage 14 is not limited to a crown-type cage.

[0076] The sealing component 20 is an annular component that lacks a core and is composed solely of elastic elements. The sealing component 20 is positioned downstream of the ball bearing 13 in the direction of compressed air supply. Figure 2 (Left side).

[0077] likeFigure 2 and Figure 4 As shown in FIG. 1, the seal member 20 has a base portion 21 of a circular ring shape extending in the radial direction, and a lip portion 22 extending obliquely from a radially inner end of the base portion 21 to the radially inner side and the axially outer side and contacting the outer peripheral surface of the inner ring 12. In addition, as shown in FIG. 2, the outer end portion of the base portion 21 in the seal member 20 alone before being mounted to the outer ring 11 has a protruding portion 21a extending in the direction becoming the axially outer side when mounted to the outer ring 11. Figure 4

[0078] Further, the outer peripheral portion of the seal member 20 is fixed to the seal mounting groove 15 formed in the axially one end portion (left end portion of FIG. 1) of the inner peripheral surface of the outer ring 11 by the retainer 30. The retainer 30 is preferably a ring-shaped member of a cross-sectional rectangular shape with a part being cut off like a C-shaped retainer. In addition, the outer diameter of the seal member 20 is set to be larger than the outer diameter of the retainer 30 in the seal mounting groove 15. Figure 2 As the material of the seal member 20, for example, a water-resistant acrylic rubber of Shore A hardness (JIS K 6253) 60 to 90, a general water-resistant fluororubber of Shore A hardness 60 to 90, and the like can be cited. The seal member 20 can obtain appropriate elastic properties and can improve durability and wear resistance by using the above-described material.

[0079] An inclined surface 12b contacting the lip portion 22 of the seal member 20 is formed in the axially one end portion (left end portion of FIG. 1) of the outer peripheral surface of the inner ring 12. The inclined surface 12b is formed to gradually reduce in diameter as it goes toward the axially outer side.

[0080] Figure 2 As shown in FIG. 3, the seal mounting groove 15 has a groove bottom surface 15a contacting the outer peripheral surface of the seal member 20, a tapered surface 15b provided on the axially outer side of the groove bottom surface 15a, connecting the groove bottom surface 15a and the outer side inner peripheral surface libl of the outer ring 11, and contacting the retainer 30, and a groove inner side surface 15c provided on the axially inner side of the groove bottom surface 15a and contacting the axially inner side surface of the seal member 20. The tapered surface 15b is formed to gradually expand in diameter as it goes toward the axially inner side.

[0081] As shown in FIG. 3, the seal mounting groove 15 has a groove bottom surface 15a contacting the outer peripheral surface of the seal member 20, a tapered surface 15b provided on the axially outer side of the groove bottom surface 15a, connecting the groove bottom surface 15a and the outer side inner peripheral surface libl of the outer ring 11, and contacting the retainer 30, and a groove inner side surface 15c provided on the axially inner side of the groove bottom surface 15a and contacting the axially inner side surface of the seal member 20. The tapered surface 15b is formed to gradually expand in diameter as it goes toward the axially inner side. Figure 3 Further, the outer side inner peripheral surface libl is a cylindrical surface formed between the outer side end portion (outer side end portion 15bl of the tapered surface 15b) of the seal mounting groove 15 and the axially end surface of the outer ring 11.

[0082]

[0083] ​​​Further, the seal member 20 is fitted into the seal mounting groove 15, and the retainer 30 is fitted into the seal mounting groove 15, so that the retainer 30 is expanded in diameter, and the outer peripheral edge of the axial outer side surface of the retainer 30 is in contact with the tapered surface 15b of the seal mounting groove 15. Thus, the force with which the retainer 30 tends to expand to the radial outer side is converted by the tapered surface 15b into a force (pressing force in the thrust direction) that presses the seal member 20 to the axial inner side, and the base portion 21 of the seal member 20 is sandwiched between the retainer 30 and the groove inner side surface 15c.

[0084] Further, the protruding portion 21a, which is a part of the radial outer end portion of the seal member 20, protrudes toward the tapered surface 15b of the seal mounting groove 15, and is therefore preferably sandwiched between the inner peripheral surface (groove bottom surface 15a in the present embodiment) of the seal mounting groove 15 and the outer peripheral surface of the retainer 30, and the protruding portion 21a is elastically deformed in the radial direction by the force with which the retainer 30 tends to expand to the radial outer side. Further, the inner peripheral surface of the seal mounting groove 15 that sandwiches the radial outer end portion of the seal member 20 can also include the tapered surface 15b.

[0085] Thus, the protruding portion 21a protrudes toward the tapered surface 15b of the seal mounting groove 15 and is caught on the outer peripheral surface of the retainer 30, thereby generating a restraining force in the radial direction of the seal member 20. Preferably, the protruding portion 21a, which is a part of 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 retainer 30, thereby generating a restraining force in the radial direction of the seal member 20. That is, in the present embodiment, a restraining force in the radial direction of the seal member 20 is generated that is not found in the related art.

[0086] Further, in consideration of dimensional tolerances of the seal mounting groove 15, the seal member 20, the retainer 30, and the like, it is preferable that a space S be formed between the inner peripheral surface of the seal mounting groove 15 and the outer peripheral surface of the retainer 30.

[0087] As described above, according to the rolling bearing 10 of the present embodiment, the radial outer end portion of the seal member 20 protrudes toward the tapered surface 15b of the seal mounting groove 15 and is caught on the outer peripheral surface of the retainer 30, thereby generating a restraining force in the radial direction of the seal member 20. Preferably, the protruding portion 21a, which is a part of 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 retainer 30, thereby generating a restraining force in the radial direction of the seal member 20. Thus, the restraining force of the seal member 20 can be further improved.

[0088] (Second Embodiment)

[0089] Next, the rolling bearing 10 according to the second embodiment will be described. Figure 5is an enlarged sectional view of the periphery of the retainer 30 in the second embodiment. For the rolling bearing 10 of the second embodiment, the structure in which the seal mounting groove 15 is provided with the protruding portion 15d is different from that of the first embodiment. The structure of the second embodiment other than the protruding portion 15d is the same as that of the first embodiment, and thus the explanation thereof is omitted.

[0090] As shown in Figure 5 , the protruding portion 15d is provided on the groove bottom surface 15a of the seal mounting groove 15 of the outer ring 11 so as to protrude toward the radially inner side. The protruding portion 15d opposes the outer peripheral surface 30a of the retainer 30 in the radial direction (up and down direction) of the rolling bearing 10. That is, the protruding portion 15d overlaps the outer peripheral surface 30a of the retainer 30 in the axial direction (left and right direction) of the rolling bearing 10. Figure 5 Figure 5

[0091] In addition, the protruding portion 15d is located at a position axially inner (right side in Figure 5 ) than the tip end 21b of the protruding portion 21a of the seal member 20. That is, the protruding portion 15d overlaps the protruding portion 21a of the seal member 20 in the axial direction.

[0092] Therefore, the radial distance A between the inner peripheral surface of the protruding portion 15d and the outer peripheral surface 30a of the retainer 30 is shorter than the radial distance B between the groove bottom surface 15a of the seal mounting groove 15 near the tip end 21b of the protruding portion 21a and the outer peripheral surface 30a of the retainer 30 (A < B). Thus, the tip end 21b of the protruding portion 21a (a portion of the protruding portion 21a axially outer than the protruding portion 15d) is constrained in the thrust direction, and thus the constraining force of the seal member 20 can be further improved.

[0093] Further, the protruding portion 15d can be formed on the entire circumference of the groove bottom surface 15a of the seal mounting groove 15, or can be formed on a part of the groove bottom surface 15a. In the case where the protruding portion 15d is formed in a circular ring shape on the entire circumference of the groove bottom surface 15a, the seal member 20 is less likely to come off, and the processing of the protruding portion 15d is also easy.

[0094] (Third Embodiment)

[0095] Next, the rolling bearing 10 according to the third embodiment will be described. Figure 6 is a sectional view showing a stopped state of the rolling bearing according to the third embodiment. The rolling bearing 10 according to the third embodiment is of the same structure as that of the first embodiment, but the following description will be made focusing on the dimensional relationship of the seal member 20 and the members around the seal member 20. In addition, the same or equivalent reference numerals are attached to the same structures as those of the first embodiment, and the description thereof is omitted.

[0096] ​​In the sealing member 20 of this embodiment, the inclination angle θ of the lip 22 relative to the base 21 of the sealing member 20, i.e., the angle between the radial direction of the base 21 and the extending direction of the lip 22, is 10° to 80°. When the inclination angle θ is less than the above range, the contact resistance becomes too large; when the inclination angle θ is greater than the above range, the flow resistance of compressed air becomes too large. Furthermore, the inclination angle θ is preferably 20° to 60°, and more preferably 25° to 50°.

[0097] Furthermore, the lip 22 is inclined radially inward and downstream (axially outward) in the direction of compressed air supply, and can abut against the inclined surface 12b of the inner ring 12. The inner circumferential surface 23 of the lip 22 is annular (conical). The inclined surface 12b of the inner ring 12 that the lip 22 can abut against is also annular (conical). Therefore, the inner circumferential surface 23 of the lip 22 can contact the inclined surface of the inner ring 12 throughout its entire circumference. That is, the sealing member 20 can seal the bearing internal space 10a between the inner circumferential surface 11b of the outer ring 11 and the outer circumferential surface 12c of the inner ring 12 throughout its entire circumference.

[0098] In addition, such as Figure 6 As shown, the supplied compressed air flows into the bearing's internal space 10a, and the pressure of the compressed air acts on the sealing member 20. Consequently, the lip 22 elastically deforms towards the downstream side of the compressed air flow. As a result, compared to the case where no compressed air pressure is applied, the contact area between the inner circumferential surface 23 of the lip 22 and the inclined surface 12b of the inner ring 12 becomes smaller. That is, the lip 22 becomes an open state that allows compressed air to flow.

[0099] The sealing component 20 has no core and is made solely of elastic material, thus becoming a structure that is easily deformable elastically as a whole. In particular, since the lip 22 and the retaining ring 30 do not interfere with each other at all, the sealing component 20 is supported on the outer ring 11 in a manner that allows for easy elastic deformation. Therefore, if compressed air acts on the sealing component 20 at a certain pressure, the inner circumference of the sealing component 20 elastically deforms outward in the axial direction, and the contact area between the inner circumferential surface 23 of the lip 22 and the inclined surface 12b of the inner ring 12 decreases.

[0100] Thus, in this structure, even when the supply pressure of compressed air is relatively low, the lip 22 of the sealing member 20 can reliably deform elastically, thereby reducing the contact area.

[0101] This allows for smooth start-up of the air turbine, reduces frictional resistance between the sealing component 20 and the inner ring 12, and enables the rotating shaft 101 to achieve approximately 400,000 mins. -1The ultra-high speed rotation is achieved. Moreover, since the inclined surface 12b is located at the downstream end of the compressed air supply direction in the outer peripheral surface 12c of the inner ring 12, the flow of compressed air between the lip 22 and the inclined surface 12b becomes smooth, enabling ultra-high speed rotation that is faster than ever before.

[0102] Here, with the sealing member 20 fixed to the sealing mounting groove 15 of the outer ring 11 by the retaining ring 30, if the radial length of the two axial sides of the base 21 of the sealing member 20 that are in contact with the retaining ring 30 and the axial inner side 15c of the sealing mounting groove 15 of the outer ring 11 is set as Lss and the inner diameter of the outer ring 11 is set as Φdg, then it is formed to satisfy the following formula (1).

[0103] 0.018≤Lss / Φdg≤0.093 (1)

[0104] This is because by setting Lss / Φdg to 0.018 or higher, the base 21 of the sealing member 20 can be ensured to be within the radial length of the sealing mounting groove 15 of the outer ring 11 and the retaining ring 30, thus reliably preventing the sealing member 20 from disengaging from the sealing mounting groove 15 of the outer ring 11 when compressed air is supplied. It should be noted that, in order to more reliably prevent the sealing member 20 from disengaging from the sealing mounting groove 15 of the outer ring 11 when compressed air is supplied, Lss / Φdg is preferably 0.027 or higher, and more preferably 0.035 or higher.

[0105] Furthermore, by setting Lss / Φdg to 0.093 or less, compressed air can be appropriately used to open and close the sealing component 20. It should be noted that, from the above perspective, Lss / Φdg is preferably 0.074 or less, and more preferably 0.047 or less.

[0106] Furthermore, in this embodiment, when the sealing member 20 is fixed to the sealing mounting groove 15 of the outer ring 11 by the retaining ring 30, the inner diameter of the retaining ring 30 is smaller than the inner diameter of the outer ring 11, and the inner circumferential surface of the retaining ring 30 is located on the inner diameter side of the outer ring 11.

[0107] In addition, such as Figure 6-8 As shown, if the circumferential gap of the retaining ring 30 is set as Ts when the sealing component 20 and the retaining ring 30 are installed in the sealing mounting groove 15 of the outer ring 11, and the axial thickness of the part of the sealing component 20 that contacts the retaining ring 30 is set as Sct, then the ratio of Ts to Sct is formed to satisfy the following formula (2).

[0108] 1≤Ts / Sct≤10 (2)

[0109] By setting Ts / Sct to 10 or less, when compressed air is supplied, it is possible to prevent the sealing member 20 from floating up from the circumferential gap Ts of the retaining ring 30, and to make it less likely for the sealing member 20 to detach from the sealing mounting groove 15 of the outer ring 11. Therefore, Ts / Sct is preferably 6 or less, and more preferably 5 or less.

[0110] Furthermore, if Ts / Sct is less than 1, the two circumferential ends will abut against each other when the diameter of the retaining ring 30 is reduced, preventing the retaining ring 30 from being sufficiently reduced in diameter. Therefore, it is preferable that Ts / Sct is 1 or more, more preferably 2 or more, and even more preferably 2.5 or more.

[0111] In addition, such as Figure 6 As shown, the sealing member 20 is formed such that if the radial length from the inclined starting portion R of the lip 22 on the axial inner side to the outermost diameter position of the contact portion with the outer peripheral surface 12c of the inner ring 12 is Skn, and the thickness of the lip 22 in the inclined direction is Skt, then the following equation (3) is satisfied.

[0112] 0.25≤Skn / Skt≤2.5 (3)

[0113] This is because by setting Skn / Skt to 0.25 or higher, the length of the lip 22 subjected to compressed air is ensured, allowing the sealing member 20 to contact the outer peripheral surface 12c of the inner ring 12 at an appropriate angle. The lip 22 is also easily deformable, thus making it easy for the sealing member 20 to become non-contact with the outer peripheral surface 12c of the inner ring 12 even with a small amount of compressed air. Furthermore, to facilitate non-contact between the sealing member 20 and the outer peripheral surface 12c of the inner ring 12, Skn / Skt is preferably 0.65 or higher, more preferably 0.90 or higher.

[0114] On the other hand, when Skn / Skt is greater than 2.5, the length of the lip 22 becomes too long, increasing the pressing pressure on the outer peripheral surface 12c of the inner ring 12, or making it difficult to contact at an appropriate angle. Therefore, if the amount of compressed air is small, the sealing member 20 may not be able to achieve non-contact with the outer peripheral surface 12c of the inner ring 12. Therefore, it is preferable for Skn / Skt to be 2.5 or less, and preferably 2.1 or less, and more preferably 1.75 or less.

[0115] Furthermore, in this embodiment, the outermost diameter position of the contact portion of the sealing member 20 that contacts the outer peripheral surface 12c of the inner ring 12 is at the boundary between the inclined surface 12b and the cylindrical surface in the outer peripheral surface 12c of the inner ring 12, but this outermost diameter position can also be the middle portion of the inclined surface 12b.

[0116] In addition, in the present embodiment, the thickness Sct of the portion of the seal member 20 that contacts the retainer 30, that is, the thickness of the axial direction of the base portion 21, and the thickness Skt in the inclined direction of the inclined portion 22 can be the same thickness or can be different.

[0117] In addition, in the seal member 20, when the radial length of the inclined start portion R on the inner side of the axial direction of the lip portion 22 and the inner diameter of the retainer 30 when the seal member 20 and the retainer 30 are installed in the seal installation groove 15 of the outer ring 11 is set as Scn, the ratio of the above-described radial length Skn and Scn is formed to satisfy the following equation (4).

[0118] 0.21 ≤ Skn / Scn ≤ 4.7 (4)

[0119] This is because, by setting Skn / Scn to be 0.21 or more, the length of the lip portion 22 that is subjected to the pressure of the compressed air can be ensured between the inner diameter of the retainer 30 and the outer circumferential surface 12c of the inner ring 12, the seal member 20 can be brought into contact with the outer circumferential surface 12c of the inner ring 12 at an appropriate angle, and thus the seal member 20 easily becomes non-contact with the outer circumferential surface 12c of the inner ring 12 even with a small amount of compressed air. Note that, in order to make the seal member 20 easily become non-contact with the outer circumferential surface 12c of the inner ring 12, Skn / Scn is preferably 0.42 or more.

[0120] On the other hand, in the case where Skn / Scn is greater than 4.7, the length of the lip portion 22 is too long, and the seal member 20 cannot be brought into contact with the outer circumferential surface 12c of the inner ring 12 at an appropriate angle, and thus the seal member 20 is difficult to become non-contact with the outer circumferential surface 12c of the inner ring 12 even with a small amount of compressed air. Therefore, Skn / Scn is preferably 4.7 or less, and more preferably 1.6 or less.

[0121] In addition, when the radial length of the outermost diameter position of the portion of the seal member 20 that contacts the outer circumferential surface 12c of the inner ring 12 and the axial center X of the rolling bearing 1 is set as Ngn, the ratio of the above-described radial length Skn and Ngn is formed to satisfy the following equation (5).

[0122] 0.025 ≤ Skn / Ngn ≤ 0.25 (5)

[0123] By satisfying equation (5), even for rolling bearings of a specified size, the length of the lip 22 receiving compressed air can be ensured, allowing the sealing member 20 to contact the outer peripheral surface 12c of the inner ring 12 at an appropriate angle. Therefore, even with a small amount of compressed air, the sealing member 20 can easily become non-contact with the outer peripheral surface 12c of the inner ring 12. It should be noted that, in order to facilitate the non-contact of the sealing member 20 with the outer peripheral surface 12c of the inner ring 12, it is preferable that 0.065≤Skn / Ngn≤0.21, and more preferably 0.090≤Skn / Ngn≤0.18.

[0124] In addition, such as Figure 6 As shown, in the sealing member 20, if the radial length from the inclined starting portion Q on the axially outer side of the lip 22 to the outermost diameter position of the contact portion with the outer peripheral surface 12c of the inner ring 12 is set as Sks, and the axial thickness at the inclined starting portion Q on the axially outer side of the lip 22 is set as Sct, then it is formed to satisfy the following formula (6).

[0125] 0.5≤Sks / Sct≤3 (6)

[0126] This is because by setting Sks / Sct to 0.5 or higher, it is possible to ensure that the length of the lip 22, which opens outward to receive compressed air, allows the sealing member 20 to contact the outer peripheral surface 12c of the inner ring 12 at an appropriate angle. Therefore, even with a small amount of compressed air, the sealing member 20 can easily become non-contact with the outer peripheral surface 21 of the inner ring 20. Furthermore, in order to facilitate the non-contact of the sealing member 20 with the outer peripheral surface 12c of the inner ring 12, Sks / Sct is preferably 0.75 or higher, and more preferably 1 or higher.

[0127] On the other hand, when Sks / Sct is greater than 3, the length of the lip 22 becomes too long, increasing the pressing pressure on the outer peripheral surface 12c of the inner ring 12, or making it difficult to contact at an appropriate angle. Therefore, with a small amount of compressed air, the sealing member 20 may not be able to achieve non-contact with the outer peripheral surface 12c of the inner ring 12. Therefore, it is preferable for Sks / Sct to be 3 or less, and more preferably 2.5 or less, and even more preferably 2 or less.

[0128] Furthermore, in the sealing member 20, when the radial length between the inclined starting portion Q on the axially outer side of the lip 22 and the inner diameter of the retaining ring 30 when the sealing member 20 and the retaining ring 30 are installed in the sealing mounting groove 15 of the outer ring 11 is set as Scs, the ratio of the aforementioned radial length Sks to Scs is formed to satisfy the following formula (7).

[0129] 0.35≤Sks / Scs≤3.75 (7)

[0130] This is because, by setting Sks / Scsto 0.35 or more, the length of the lip portion 22 that receives compressed air can be ensured between the inner diameter of the retainer 30 and the outer peripheral surface 12c of the inner ring 12, the sealing member 20 can be brought into contact with the outer peripheral surface 12c of the inner ring 12 at an appropriate angle, and thus the sealing member 20 easily becomes non-contact with the outer peripheral surface 12c of the inner ring 12 even with a small amount of compressed air. Note that, in order to make the sealing member 20 easily become non-contact with the outer peripheral surface 12c of the inner ring 12, Sks / Scsis preferably 0.62 or more.

[0131] On the other hand, in the case where Sks / Scsis greater than 3.75, the length of the lip portion 22 is too long, and the sealing member 20 cannot be brought into contact with the outer peripheral surface 12c of the inner ring 12 at an appropriate angle, and thus the sealing member 20 is difficult to become non-contact with the outer peripheral surface 12c of the inner ring 12 even with a small amount of compressed air. Therefore, Sks / Scsis preferably 3.75 or less, and more preferably 2.0 or less.

[0132] Further, in the case where the radial length between the outermost diameter position of the portion of the sealing member 20 that contacts the outer peripheral surface 12c of the inner ring 12 and the shaft center X of the rolling bearing 10 is set to Ngn, the ratio of the above-described radial length Sks to Ngn is made to satisfy the following equation (8).

[0133] 0.05 ≤ Sks / Ngn ≤ 0.31 (8)

[0134] By satisfying this equation (8), even with a rolling bearing of a prescribed size, the length of the lip portion 22 that receives compressed air can be ensured, the sealing member 20 can be brought into contact with the outer peripheral surface 12c of the inner ring 12 at an appropriate angle, and thus the sealing member 20 easily becomes non-contact with the outer peripheral surface 12c of the inner ring 12 even with a small amount of compressed air. Further, in order to make the sealing member 20 easily become non-contact with the outer peripheral surface 12c of the inner ring 12, 0.10 ≤ Sks / Ngn ≤ 0.23 is preferable.

[0135] Further, in the case where the radial length between the inner peripheral surface lib of the outer ring 11 and the inner peripheral surface of the retainer 30 in the state where the sealing member 20 is fixed to the seal mounting groove 15 of the outer ring 11 by the retainer 30 is set to Tm, and the radial length between the inner peripheral surface lib of the outer ring 11 and the outer peripheral surface 12c of the inner ring 12 is set to An, the ratio of Tm to An is made to satisfy the following equation (9).

[0136] 0 ≤ Tm / An ≤ 0.5 (9)

[0137] This is because by setting Tm / An to 0 or higher, the sealing component 20 is difficult to detach from the outer ring 11 even when compressed air is supplied. Furthermore, considering the tolerances of the depth and angle of the sealing mounting groove 15 of the outer ring 11, the radial thickness of the retaining ring 30, etc., Tm / An is preferably 0.05 or higher, and more preferably 0.12 or higher.

[0138] Furthermore, by setting Tm / An to 0.5 or less, the sealing member 20 can easily become non-contact with the outer peripheral surface 21 of the inner ring 20 when compressed air is supplied. It should be noted that, in order to make it easy for the sealing member 20 to become non-contact with the outer peripheral surface 12c of the inner ring 12, Tm / An is preferably 0.28 or less.

[0139] Therefore, by satisfying equation (9), when supplying compressed air, even if less compressed air is used for energy saving, the sealing component 20 can become non-contact with the outer peripheral surface 12c of the inner ring 12, and the sealing component 20 is not easy to detach from the sealing mounting groove 15 of the outer ring 11.

[0140] Furthermore, when the drive of the dental air turbine handpiece is stopped and the supply of compressed air to the turbine blades 122 ceases, the pressure of the compressed air acting on the lip 22 decreases. Consequently, the lip 22 returns to its original position. Figure 6 The state shown is such that the inner circumferential surface 23 of the lip 22 is in contact with the inclined surface 12b of the inner ring 12 throughout its entire circumference. That is, the lip 22 is in the closed state, and the lip 22 functions as a brake for the inner ring 12. In this case, since the inner circumferential surface 23 of the lip 22 is in contact with the inclined surface 12b of the inner ring 12 throughout its entire circumference, the best braking effect based on the frictional resistance between the sealing member 20 and the inner ring 12 can be obtained. As a result, the rotating shaft 121 fixed to the inner ring 12 can be stopped most quickly.

[0141] Furthermore, when the sealing member 20 is fixed to the sealing mounting groove 15 of the outer ring 11 by the retaining ring 30, and the radial length between the inner circumferential surface of the retaining ring 30 and the outer circumferential surface 12c of the inner ring 12 is set to San, the ratio of the axial thickness Sct of the base 21 to San is formed to satisfy the following formula (10).

[0142] 0.1≤Sct / San≤0.6 (10)

[0143] This is because by setting Sct / San to 0.1 or higher, the air turbine can be quickly stopped when the sealing member 20 is pressed against the inner ring 12 and compressed air is no longer supplied. Furthermore, for even faster stopping, it is preferable to set Sct / San to 0.15 or higher, and more preferably to 0.2 or higher.

[0144] Further, by setting Sct / San to 0.6 or less, the seal member 20 is easily elastically deformed, and thus the seal member 20 easily becomes non-contact with the outer circumferential surface 12c of the inner ring 12 when the compressed air is supplied. Further, in order to make the seal member 20 more easily become non-contact with the outer circumferential surface 12c of the inner ring 12, Sct / San is preferably 0.4 or less, and more preferably 0.3 or less.

[0145] Thus, by satisfying the formula (10), the rapid stop at the time of the supply of the compressed air is cancelled, which is useful for shortening the treatment time or the like, and even if the amount of the compressed air is small when the compressed air is supplied, the seal member can become non-contact with the outer circumferential surface of the inner ring.

[0146] Further, the radial distance Thn between the outer circumferential surface of the retainer 30 and the outer side end portion 15bl of the tapered surface 15b of the seal mounting groove 15 in the state where the seal member 20 is fixed to the seal mounting groove 15 of the outer ring 11 by the retainer 30 and the above-described radial length Lss are formed so as to satisfy the following formula (11).

[0147] 0.05 ≤ Thn / Lss ≤ 1 (11)

[0148] This is because, by making Thn / Lss 0.05 or more, the radial length in which the retainer 30 is embedded in the seal mounting groove 15 is ensured, and thus the seal member 20 can be reliably prevented from being detached from the seal mounting groove 15 of the outer ring 11 when the compressed air is supplied. Note that, in order to more reliably prevent the seal member 20 from being detached from the seal mounting groove 15 of the outer ring 11 when the compressed air is supplied, Thn / Lss is preferably 0.08 or more, and more preferably 0.10 or more.

[0149] Further, by making Thn / Lss 1 or less, the radial dimension of the retainer 30 is ensured, and the installation of the seal member 20 and the retainer 30 becomes easy. Note that, in order to make the installation of the seal member 20 and the retainer 30 easier, Thn / Lss is preferably 0.8 or less, and more preferably 0.6 or less.

[0150] Further, since the lip portion 22 of the seal member 20, which is particularly easily elastically deformed, is brought into contact with the inclined surface 12b of the inner ring 12, the contact pressure of the seal member 20 with the inclined surface 12b can be reduced compared to the case of being in contact in the radial direction. As a result, the opening and closing operation of the seal member 20 can be performed using the compressed air smoothly and with high responsiveness. Further, compared to the conventional structure, the above-described contact pressure can be reduced with a smaller pressure of the compressed air, and further improvement of the rotational speed of the rotational shaft 121 and shortening of the stop time can be simultaneously achieved.

[0151] By providing a contact surface at the end lip 22 of the sealing member 20 that makes surface contact with the inclined surface 12b of the inner ring 12, the surface pressure acting on the sealing member 20 is reduced, and wear is alleviated. In addition, by increasing the contact area, the sealing performance is improved.

[0152] Furthermore, the contact surface of the lip 22 can also be a surface that makes line contact with the inclined surface 12b of the inner ring 12. In this case, compared with the case of surface contact, the frictional resistance is reduced, which is beneficial for high-speed rotation.

[0153] Especially in dental air turbine handpieces, extremely high-speed rotation is required during tooth cutting, and a rapid rotation stop performance of less than 2 seconds, preferably less than 1 second, is required when stopping. According to this structure, the aforementioned effects of increasing rotation speed and shortening stopping time can be consistently achieved, thus significantly improving the ease of use of dental air turbine handpieces.

[0154] Furthermore, when driving the dental air turbine handpiece, compressed air is less likely to leak from the bearing compared to cases without sealing components, thus reducing noise during operation and achieving high quietness.

[0155] In addition, such as Figure 6 As shown, a pair of rolling bearings are arranged on the rotating shaft 121, but the sealing member 20 is located at one axial end of the outer ring 11 on the side opposite to the compressed air inlet. This allows for oil spraying from the pair of rolling bearings to each other, thus supplying lubricating oil to each rolling bearing from the bearing end side where the sealing member 20 is not located. Furthermore, since the sealing member 20 is located on the opposite side of the oil spraying side, no leakage occurs from each rolling bearing to the outside of the head 110.

[0156] Typically, dental air turbine handpieces undergo high-temperature cleaning and sterilization in an autoclave after use. This process reduces the amount of lubricating oil in the rolling bearings, but since the sealing component 20 is only located at one axial end of the rolling bearing, lubricating oil can be easily supplied from the other axial end. Therefore, the rolling bearings are always in a good lubricated state, enabling stable rotational drive of the rotating shaft 121.

[0157] Furthermore, the present invention is not limited to the contents illustrated in the above embodiments, and appropriate modifications can be made without departing from the spirit of the present invention.

[0158] In addition, the retaining ring is not limited to a rectangular cross-section; it can also be a circular cross-section.

[0159] Alternatively, the retaining ring can be configured to have a conical surface and the sealing mounting groove can be formed into a rectangular cross-section, so that the conical surface of the retaining ring contacts the corner of the rectangular sealing mounting groove.

[0160] For example, the rim portion 7 of the cage 5 used in the rolling bearing 1 of the above-described embodiment is arranged on the position on the upstream side of the supply direction of the compressed air from the rolling element 3, but is not limited thereto, and can be a structure in which the rim portion 7 is arranged on the side of the sealing member on the opposite side in the axial direction.

[0161] Further, since the sealing member is arranged only on one end side in the axial direction of the rolling bearing 1, the groove portion 13 of the outer ring 10 and the inclined surface 12b of the inner ring 20 are formed only on one end side in the axial direction, but are not limited thereto, and can be a structure in which the groove portion 13 of the outer ring 10 and the inclined surface 12b of the inner ring 20 are symmetrically formed also on the other end side in the axial direction. In this case, although one of the pair of inclined surfaces is not used, in the assembly process of the rolling bearing, it is not necessary to pay attention to the assembly direction, and the work process can be simplified.

[0162] Further, the wall thickness of the inclined portion of the sealing member can be a constant thickness, but can gradually decrease toward the inner side in the radial direction. In this case, the thickness Skt in the inclined direction of the inclined portion 33 is the thickness of the thickest portion.

[0163] Further, the present application is based on Japanese Patent Application (Japanese Patent Application No. 2020-042731) filed on March 12, 2020, and Japanese Patent Application (Japanese Patent Application No. 2021-017471) filed on February 5, 2021, the contents of which are incorporated herein by reference.

Claims

1. A rolling bearing, characterized in that, Possessing: an outer ring having an outer ring raceway surface on an inner peripheral surface; an inner ring having an inner ring raceway surface on an outer peripheral surface; a plurality of rolling elements configured to be able to roll between the outer ring raceway surface and the inner ring raceway surface; and a seal member fixed to a seal mounting groove formed at an axial end portion of the outer ring by a retainer, and sealing an axial end portion of a bearing internal space between the outer ring and the inner ring, the seal member before being mounted to the outer ring has a protruding portion at a radially outer end portion, the protruding portion extending in the axial direction so as to extend in a direction that becomes an axial outer side when the seal member is mounted to the outer ring, an outer diameter of the seal member is larger than an outer diameter of the retainer in the seal mounting groove, the seal mounting groove has: a groove bottom surface that comes into contact with an outer peripheral surface of the seal member; a tapered surface provided on an axial outer side of the groove bottom surface, and connecting the groove bottom surface and an inner peripheral surface of the outer ring, and the tapered surface coming into contact with the retainer; and a groove inner side surface provided on an axial inner side of the groove bottom surface, and coming into contact with an axial inner side surface of the seal member.

2. The rolling bearing according to claim 1, characterized in that: the protruding portion of the seal member is sandwiched between the inner peripheral surface of the seal mounting groove and the outer peripheral surface of the retainer.

3. The rolling bearing according to claim 2, characterized in that: a protruding portion is provided on the groove bottom surface of the seal mounting groove, the protruding portion being radially opposed to the outer peripheral surface of the retainer and being located at a position that is axially inner than a distal end of the protruding portion of the seal member.

4. The rolling bearing according to any one of claims 1 to 3, characterized in that: the rolling bearing is used for a dental air turbine.

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