Rolling bearing

Abstract

In this rolling bearing, a plurality of balls interposed between an inner ring and an outer ring are held by a cage, and a seal member (6) is attached to the outer ring for sealing a bearing space between the inner ring and the outer ring. A seal groove (7) is formed in the circumferential direction on the outer circumferential surface of the inner ring, the seal member (6) is a contact-type seal member, and the lip portion (15) of the seal member is in contact with the seal groove (7). The outer groove wall surface (7c) of the seal groove (7) is formed as an inclined surface which is inclined toward the outer diameter side as the inclined surface extends toward the outer side in the axial direction. The front end portion (15c) of the lip portion (15) of the seal member (6) is formed in a rounded shape in contact with the outer groove wall surface (7c) of the seal groove (7) at a contact angle of 80-100 degrees. The inclination angle (I) of the outer groove wall surface (7c) with respect to the axial direction is 55-65 degrees.

Description

[0001] Related Applications

[0002] This application claims the benefit of Japanese Patent Application No. 2022-161222, filed on October 5, 2022, the entirety of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to a rolling bearing and to a technology capable of simultaneously suppressing the outflow of grease and the like from the inside of the bearing and the intrusion of foreign matter from the atmosphere. Background Art

[0004] exist Fig.13 In the rolling bearing 50 for the servo motor shown, for the model in which the encoder 52 is arranged near the motor 51, it is necessary to use a contact sealing component as a low dust emission of the rolling bearing 50 to prevent malfunction of the encoder 52 due to dust emission from the inside of the bearing and dust adhesion to the encoder 52 due to seal wear.

[0005] In the sealing structure of the rolling bearing in the prior art, Fig.14 As shown, the main lip 53 is brought into contact with the outer groove wall surface of the seal groove 54, and a labyrinth seal is formed between the front end of the auxiliary lip 55 and the inner groove wall surface of the seal groove 54 to achieve low torque and high sealing.

[0006] [Prior art literature]

[0007] [Patent Document]

[0008] Patent Document 1: Japanese Patent Application Publication No. 2006-170313 Summary of the invention

[0009] [Problems to be solved by the invention]

[0010] When the inner ring of the rolling bearing rotates at a high speed, the internal pressure of the rolling bearing increases. Therefore, if the sealing performance is insufficient, grease will be ejected to the outside together with the air, contaminating the surrounding area of ​​the rolling bearing.

[0011] Therefore, the applicant has found that by suppressing changes in surface pressure distribution caused by changes in seal shape and interference during seal contact, dust emission from grease etc. inside the bearing and the generation of wear powder caused by wear of the rubber seal can be suppressed.

[0012] An object of the present invention is to provide a rolling bearing which can simultaneously suppress the outflow of grease etc. from the inside of the bearing and the intrusion of foreign matter from the atmosphere even when the internal pressure of the bearing increases when the rolling bearing rotates.

[0013] [Technical solution to the problem]

[0014] The rolling bearing of the present invention relates to a rolling bearing in which a plurality of balls sandwiched between an inner ring and an outer ring are held in a retainer, a sealing member is mounted on the outer ring for sealing a bearing space between the inner ring and the outer ring, and a sealing groove is formed in a circumferential direction on an outer peripheral surface of the inner ring, characterized in that:

[0015] The above-mentioned sealing component is a contact sealing component, which contacts the above-mentioned sealing groove with the outer side of the lip portion, and the outer groove wall surface of the above-mentioned sealing groove is formed as an inclined surface. The inclined surface is inclined toward the outer diameter side as it extends axially outward. The inclination angle of the above-mentioned outer groove wall surface relative to the axial direction is 55~65°, and the front end portion of the above-mentioned lip portion has a lip shape with a rounded corner shape (Japanese: R shape) that contacts the above-mentioned outer groove wall surface at 80~100°.

[0016] According to this structure, by setting the inclination angle of the outer groove wall surface to 55 to 65 degrees with respect to the axial direction and setting the front end of the lip to a rounded shape, the front end of the lip can form a surface pressure distribution for the bearing internal pressure generated when the rolling bearing rotates, so that the front end of the lip can maintain a state of contact along the normal direction, that is, a so-called normal contact state. Therefore, even when the bearing internal pressure rises when the rolling bearing rotates, it is possible to simultaneously suppress the outflow of grease from the inside of the bearing and the intrusion of foreign matter from the atmosphere.

[0017] If the inclination angle of the outer groove wall is less than 55°, the seal member is easily overturned by the bearing internal pressure, which is not suitable. If the inclination angle of the outer groove wall is greater than 65°, the front end of the lip will contact the above-mentioned inclined surface too strongly when the bearing internal pressure is generated, resulting in an increase in torque or an increase in heat generation, which is not suitable.

[0018] The front end of the lip may be in the shape of an arc with a radius of 0.03 to 0.09 mm. In this case, when the rolling bearing rotates, the change in the surface pressure distribution of the lip can be more reliably suppressed, and at the same time, the undesirable torque increase, the undesirable heating of the lip, etc. can be suppressed.

[0019] If the radius of the tip of the lip is less than 0.03mm, it is considered difficult to achieve normal contact when the bearing internal pressure changes during the rotation of the rolling bearing and the contact position of the lip is slightly misaligned. If the radius of the tip of the lip is greater than 0.09mm, when the bearing internal pressure rises during the rotation of the rolling bearing, the tip of the lip strongly contacts the inclined surface, the contact surface increases, causing increased torque or heat, and is therefore not suitable.

[0020] The sealing member has a core iron and a rubber material, the lip portion is made of the rubber material, and the surface roughness of a part or the whole part of the inner side of the lip portion located on the inner diameter side of the PCD can be Ra=0.4-2.5μm. In this case, the desired dust emission suppression effect can be achieved, and the resistance to grease can be suppressed to a low level.

[0021] If the arithmetic mean roughness Ra is less than 0.4 μm, the effect of suppressing grease migration becomes small and the dust suppression effect is also small. If the arithmetic mean roughness Ra is greater than 2.5 μm, that is, too rough, the resistance to grease becomes too large, which is not conducive to rotation and is therefore not suitable.

[0022] The sealing member may be provided with an air outlet for releasing the internal pressure of the rolling bearing. In this case, when the rolling bearing rotates, the bearing internal pressure is released from the air outlet, thereby suppressing the outflow of grease due to excessive changes in the seal interference and the increase in the bearing internal pressure.

[0023] The outer peripheral side portion of the sealing component on at least one side is provided with a plurality of the air outlets, and the air outlets include radial air outlets formed in the radial direction and axial air outlets formed in the axial direction, and the radial air outlets and the axial air outlets can be provided at different circumferential positions. Thus, by staggering the circumferential positions (circumferential phases) of the radial air outlets and the axial air outlets, the outflow of grease can be more reliably suppressed.

[0024] The lip of the sealing member may be provided with an air outlet for releasing the internal pressure of the rolling bearing. In this case, when the rolling bearing rotates, the internal pressure of the bearing is released from the air outlet, thereby suppressing the outflow of grease due to excessive changes in the seal interference and the increase in the internal pressure of the bearing.

[0025] The air outlet provided on the sealing component may be located on one or both sides of the sealing component in the axial direction.

[0026] The sealing member has an auxiliary lip portion protruding axially inward from the base end portion, and a labyrinth seal can be formed between the front end portion of the auxiliary lip portion and the inner groove wall surface of the sealing groove. In this case, the effect of preventing grease and the like from flowing out and the effect of preventing foreign matter from entering can be further improved by the lip portion and the auxiliary lip portion serving as the contact sealing member.

[0027] Two auxiliary lips may be provided at intervals in the radial direction, and a grease reservoir may be provided between the two auxiliary lips. In this case, the grease stored in the grease reservoir can intercept the grease that helps lubrication and prevent it from flowing out, and can also prevent foreign matter from invading from the atmosphere side.

[0028] The retainer may also include a grease receiving portion that can receive grease on the inner diameter side of the retainer. In this case, when the bearing is running, the grease remaining in the stationary space is received in the grease receiving portion under the action of centrifugal force and further supplied to the raceway surface. As a result, the grease life can be extended compared to a rolling bearing having a retainer without a grease receiving portion.

[0029] The present invention includes any combination of at least two configurations disclosed in the claims and / or the specification and / or the drawings. In particular, the present invention includes any combination of more than two configurations in each claim. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be more clearly understood by referring to the following description of the preferred embodiments with reference to the accompanying drawings. However, the embodiments and the accompanying drawings are for illustration and description only and should not be used to limit the scope of the present invention. The scope of the present invention is determined by the claims. In the accompanying drawings, the same component numbers in multiple drawings represent the same or equivalent parts.

[0031] [ Figure 1 ] is a cross-sectional view of a rolling bearing according to the first embodiment of the present invention.

[0032] [ Figure 2 ] is an enlarged cross-sectional view of the lip portion of the sealing component of the rolling bearing.

[0033] [ Figure 3 ] is a three-dimensional diagram of the sealing component.

[0034] [ Figure 4A ] is an enlarged partial cross-sectional view of the sealing component cut through the radial air outlet.

[0035] [ Figure 4B ] is an enlarged cross-sectional view of a portion of the sealing component cut through the axial air outlet.

[0036] [ Figure 5A ] is an enlarged cross-sectional view showing the contact condition between the sealing component and the sealing groove.

[0037] [ Figure 5B ] is a diagram showing the surface pressure distribution when the interference of the sealing component is minimum.

[0038] [ Figure 5C ] is a diagram showing the surface pressure distribution when the interference of the sealing component is maximum.

[0039] [ Figure 6 ] is a three-dimensional diagram of the retainer of the rolling bearing.

[0040] [ Fig. 7A] is a cross-sectional view of a rolling bearing related to another embodiment of the present invention cut at the radial air outlet.

[0041] [ Figure 7B ] is a cross-sectional view of the rolling bearing cut through the axial air outlet.

[0042] [ Figure 8 ] is an enlarged cross-sectional view of the lip portion of the sealing component of the rolling bearing.

[0043] [ Fig. 9A ] is an enlarged cross-sectional view showing the contact state between the sealing component and the sealing groove.

[0044] [ Fig. 9B ] is a diagram showing the surface pressure distribution when the interference of the sealing component is minimum.

[0045] [ Fig. 9C ] is a diagram showing the surface pressure distribution when the interference of the sealing component is maximum.

[0046] [ Fig.10 ] is an enlarged cross-sectional view of the lip portion of the sealing component in a rolling bearing related to further other embodiments of the invention.

[0047] [ Fig.11 ] is a cross-sectional view of a rolling bearing related to further other embodiments of the invention.

[0048] [ Fig.12 ] is a three-dimensional view of a retainer of a rolling bearing related to further another embodiment of the invention.

[0049] [ Fig.13 ] is a diagram schematically showing rolling bearings, etc. for servo motors.

[0050] [ Fig.14 ] is an enlarged cross-sectional view partially showing the sealing structure of a rolling bearing of a conventional example.

[0051] [ Fig.15A ] is an enlarged cross-sectional view showing the contact state between the sealing component and the sealing groove of a conventional example.

[0052] [ Fig. 15B ] is a diagram showing the surface pressure distribution when the interference of the sealing component is minimum.

[0053] [ Fig. 15C ] is a diagram showing the surface pressure distribution when the interference of the sealing component is maximum. DETAILED DESCRIPTION

[0054] [First embodiment]

[0055] The rolling bearing according to the first embodiment of the present invention will be described below. Figures 1 to 6 Provide explanation.

[0056] <General structure of rolling bearing>

[0057] like Figure 1 As shown, the rolling bearing 1 is a deep groove ball bearing having inner and outer rings 2, 3, balls 4, a retainer 5 and a sealing member 6. A plurality of balls 4 sandwiched between the raceway surfaces 2a, 3a of the inner and outer rings 2, 3 are retained at a certain interval in the circumferential direction by the retainer 5, and a sealing member 6 for sealing the bearing space between the inner ring 2 and the outer ring 3 is mounted on the outer ring 3. In this example, the sealing members 6, 6 are mounted on both axial sides of the inner surface of the outer ring.

[0058] like Figure 6 As shown, the retainer 5 of this example is made of synthetic resin and is a two-piece combined retainer formed by engaging two annular bodies 5a, 5a of the same shape. The retainer 5 retains the ball 4 in a bag portion Pt whose axial bag shape is formed into a cylindrical shape. Each annular body 5a has a plurality of semi-cylindrical bag wall portions 5c and a plurality of connecting plate portions 5b. The two bag wall portions 5c, 5c are combined with each other in the axial direction to form a bag portion Pt. The above-mentioned bag portions Pt are evenly arranged on the circumference. The retainer 5 has an engaging hole Ka and an engaging claw Kb, which engage with each other in the connecting plate portion 5b between the bag portions Pt. The retainer 5 is assembled by engaging the engaging hole Ka with the engaging claw Kb so that the two annular bodies 5a, 5a of the same shape are engaged. In addition, the bag shape of the retainer 5 can be a spherical shape. Grease is sealed in the above-mentioned bearing space.

[0059] <About sealing structure>

[0060] Each sealing member 6 is a contact sealing member, and its lip 15 contacts the sealing groove 7. The sealing groove 7 is formed in the circumferential direction on the outer circumferential surface of the inner ring 2, and a sealing member fixing groove 9 is provided on the inner circumferential surface of the outer ring 3 opposite to each sealing groove 7. Figure 1 to Figure 3 As shown, the sealing component 6 is obtained by molding a rubber material 11 on a core iron 10, and the outer peripheral edge of the sealing component 6 is embedded in the sealing component fixing groove 9 of the outer ring 3 and fixed. Figure 3 , Figure 4A and Figure 4B As shown, the outer peripheral portion of the sealing member 6 is provided with an air outlet 12 for releasing the internal pressure of the rolling bearing.

[0061] exist Figure 4A and Figure 4BIn the figure, although a part of the outer peripheral side portion of the seal member 6 is shown as being embedded in the seal member fixing groove 9 of the outer ring 3, a part of it is an interference fit and is actually embedded in the seal member fixing groove 9 in an elastically deformed state. In addition, a part of the lip portion 15 of the seal member 6 is also shown as being embedded in the seal groove 7 of the inner ring 3, but a part of it is an interference fit and is actually in contact with the seal groove 7 in an elastically deformed state. This is also true for the seal structure described later ( Fig. 7A , Figure 7B , Fig.10 , Fig.11 ).

[0062] The sealing member 6 is provided with a plurality of air outlets 12. The air outlets 12 include: radial air outlets 12a ( Figure 4A ) and an axial air outlet 12b ( Figure 4B ). The air outlets 12a and 12b are respectively formed by grooves provided on the outer peripheral side of the sealing member 6. The radial air outlets 12a and the axial air outlets 12b are provided at different circumferential positions.

[0063] Specifically, if Figure 3 , Figure 4A and Figure 4B As shown, two radial air outlets 12a, 12a are arranged at a phase interval of 180° in the circumferential direction on the following inner side surface, which is the surface facing the inner groove wall surface 9a of the sealing component fixing groove 9 in the outer peripheral side portion of the sealing component 6. The radial air outlet 12a and the inner groove wall surface 9a form a hole. In addition, in the outer peripheral side portion of the sealing component 6, an axial air outlet 12b is arranged on the outer peripheral surface of the outer peripheral groove wall surface 9c facing the sealing component fixing groove 9. The axial air outlet 12b and the outer peripheral groove wall surface 9c form a hole. The axial air outlet 12b is arranged at a circumferential position that is 90° phase-shifted relative to the radial air outlet 12a. These radial air outlets 12a, 12a and the axial air outlet 12b are connected through the outer peripheral groove wall surface 9c of the sealing component fixing groove 9. Therefore, when the rolling bearing 1 rotates, the bearing internal pressure can be released from the two radial air outlets 12a, 12a through the axial air outlet 12b. In addition, the circumferential positions of the air outlets 12a and 12b in the axial direction and the radial direction are not limited to the above-mentioned phases.

[0064] like Figure 1 , Figure 2As shown, the sealing groove 7 of the inner ring 2 has an inner groove wall surface 7a, a groove bottom surface 7b and an outer groove wall surface 7c in order toward the axial outer side. The inner groove wall surface 7a is connected to the inner ring shoulders arranged on both sides of the raceway surface 2a in the axial direction, and forms an inclined surface, which is inclined toward the inner diameter side as it extends axially outward. The groove bottom surface 7b smoothly connected to the inner groove wall surface 7a extends substantially parallel to the axial direction. The outer groove wall surface 7c is smoothly connected to the groove bottom surface 7b, and forms an inclined surface, which is inclined toward the outer diameter side as it extends axially outward. The inclination angle I of the outer groove wall surface 7c relative to the axial direction is set to 55 to 65 degrees.

[0065] If the inclination angle I of the outer groove wall surface 7c is less than 55°, the seal member 6 is easily turned over by the bearing internal pressure, which is not suitable. If the inclination angle of the outer groove wall 7c is greater than 65°, the front end of the lip 15 will contact the inclined surface too strongly when the bearing internal pressure is generated, resulting in an increase in torque or an increase in heat generation, which is not suitable.

[0066] like Figure 2 As shown, the inner peripheral portion 13 of the sealing member 6 extending radially inwardly from the inner diameter of the core iron 10 is made of the rubber material 11. The rubber material 11 is usually made of nitrile rubber, but other materials such as acrylic rubber, silicone rubber, and fluororubber may also be used depending on the operating temperature.

[0067] The inner peripheral portion 13 of the sealing member 6 includes a neck portion 14 whose wall thickness decreases as it extends toward the inner diameter side, a main lip portion (lip) 15 connected to the neck portion 14, and an auxiliary lip portion 16. The neck portion 14, the main lip portion 15, and the auxiliary lip portion 16 are integrally formed. The main lip portion 15 is connected to the inner diameter side end portion of the neck portion 14, and the auxiliary lip portion 16 protrudes axially inward from the inner side surface portion of the base end portion 15a of the main lip portion 15. Figure 1 As shown, a labyrinth seal Rs is formed between the front end portion of the auxiliary lip portion 16 and the inner groove wall surface 7 a of the seal groove 7 .

[0068] like Figure 2As shown in FIG. 1 , the main lip 15 includes a base end 15a which is inclined toward the inner diameter side as it extends axially outward, a lip body 15b which extends from the base end 15a in the inner diameter direction, and a front end 15c which is provided at the outer side surface portion of the front end side of the lip body 15b. The front end 15c of the main lip 15 is formed into a rounded shape which contacts the outer groove wall surface 7c of the seal groove 7 in the normal direction. The outer diameter surface 15ca of the front end 15c of the main lip 15 is inclined toward the inner diameter side as it extends axially outward, and smoothly connects with the rounded shape. When the inclination angle I of the outer groove wall surface 7c of the seal groove 7 is 55 to 65 degrees, the front end 15c of the main lip 15 is in an arc shape with a radius of 0.03 mm or more and 0.09 mm or less.

[0069] If the radius R of the front end portion 15c of the lip 15 is less than 0.03mm, it is considered difficult to achieve normal contact when the bearing internal pressure changes during the rotation of the rolling bearing and the contact position of the lip 15 is slightly misaligned. If the radius R of the front end portion 15c of the lip 15 is greater than 0.09mm, when the bearing internal pressure rises during the rotation of the rolling bearing, the front end portion 15c of the lip 15 strongly contacts the inclined surface, and the contact surface increases, resulting in increased torque or heat generation, so it is not suitable.

[0070] The dimensions of other parts are set as follows.

[0071] *The wall thickness A of the base end of the main lip, the wall thickness B of the lip body: 80%±10% of the thickness t of the core iron.

[0072] * Radial length D of the lip body portion: 55% ± 10% of the radial length C of the inner peripheral portion (cross section of the rubber portion) of the sealing member.

[0073] *Axial dimension E from the inner side surface of the lip body to the front end: less than twice the wall thickness B of the lip body.

[0074] *The radial dimension F from the inner diameter surface of the auxiliary lip portion to the inner diameter side end portion of the lip main body portion is 60% ± 10% of the radial length C of the cross section of the rubber portion.

[0075] *Inclination angle G of the outer diameter surface of the front end portion relative to the axial direction: 30°±20°.

[0076] *The inclination angle H of the base end portion relative to the lip body portion: 135°±20°.

[0077] Again, if Figure 4A As shown, in the sealing component 6, the inner side surface of the main lip 15, the inner diameter surface, the inner side surface and the outer diameter surface of the auxiliary lip 16, the inner side surface of the neck 14 and all parts of the inner side surface of the rubber material 11 connected to the inner side surface of the neck ( Figure 4A The surface roughness covered by the portion marked by the dotted line L1 in the figure has an arithmetic average roughness Ra of 0.4 μm or more and 2.5 μm or less. If the arithmetic average roughness Ra is less than 0.4 μm, the effect of suppressing the movement of grease becomes smaller and the dust suppression effect is small. If the arithmetic average roughness Ra is greater than 2.5 μm, that is, it is too rough, the resistance to grease becomes too large, which is not conducive to rotation and is therefore not suitable.

[0078] In this example, the surface roughness is specified not only for the inner surface of the main lip 15 but also for the inner surfaces of the auxiliary lip 16 and the neck 14. However, the surface roughness of at least a part or all of the inner surface of the main lip 15 that is closer to the inner diameter than the pitch circle diameter (PCD) can be specified to be not less than 0.4 μm and not more than 2.5 μm in terms of the arithmetic mean roughness Ra.

[0079] <FEM Analysis Results of Contact State and Surface Pressure Change of Sealing Member 6>

[0080] Figure 5A It is an enlarged cross-sectional view showing the contact state between the sealing member 6 and the sealing groove 7 . Figure 5B This is a diagram showing the surface pressure distribution when the interference of the sealing component is minimum. Figure 5C FIG. 4 is a diagram showing the surface pressure distribution when the interference of the sealing member is maximum. Figure 5B and Figure 5C Each vertical axis in the figure represents the surface pressure of the lip of the sealing component (unit: kgf / mm 2 ), each horizontal axis represents the coordinate (unit: mm) of the outer diameter side inclination direction of the contact portion when the contact position of the front end portion 15c of the lip and the seal groove 7c on the inner diameter side is the reference position (zero).

[0081] according to Figure 5B , Figure 5C The analytical results shown in the figure show that the surface pressure of the lip 15 changes little when the interference of the sealing member 6 is minimum and maximum. Fig.15A , Fig. 15B and Fig. 15C In the analysis results of the sealing member 56 of the conventional example shown in , when the interference of the sealing member 56 is the smallest ( Fig. 15B ) and maximum time ( Fig. 15C ), the surface pressure variation of the lip 57 becomes relatively large and is concentrated at one point, so it is not suitable.

[0082] Next, the evaluation results of this embodiment are described. Table 1 shows the evaluation results of sealing, low torque and low heat generation based on the inclination angle of the outer groove wall. In the table, "○" indicates good, "△" indicates that the effect is worse than "○", and "×" indicates unqualified. From the results in Table 1, it can be seen that by setting the inclination angle of the outer groove wall to 55-65°, a rolling bearing with high sealing performance, low torque and low heat generation can be obtained. In addition, the contact angle between the rounded lip and the outer groove wall is 90°.

[0083] [Table 1]

[0084] Inclination angle of outer groove wall 45° 50° 55° 60° 65° 70° 75° Sealing × △ ○ ○ ○ ○ ○ Low torque, low heat ○ ○ ○ ○ ○ △ ×

[0085] Table 2 shows the evaluation results of sealing performance, low torque and low heat generation based on the contact angle between the rounded lip and the outer groove wall. In the table, "○" indicates good, "△" indicates that the effect is worse than "○", and "×" indicates unqualified. From the results in Table 2, it can be seen that setting the contact angle between the rounded lip and the outer groove wall to 80-100° can obtain a rolling bearing with high sealing performance, low torque and low heat generation. In addition, the inclination angle of the outer groove wall is 60°.

[0086] [Table 2]

[0087]

[0088] <Effects>

[0089] According to the rolling bearing 1 described above, by setting the inclination angle I of the outer groove wall surface 7c to 55-65° and setting the front end 15c of the lip 15 to a rounded shape, the front end of the lip 15 can form a surface pressure distribution for the bearing internal pressure generated when the rolling bearing 1 rotates, so that the front end 15c of the lip 15 can maintain a state of contact along the normal direction, that is, a so-called normal contact state. Therefore, even when the bearing internal pressure increases when the rolling bearing 1 rotates, the outflow of grease from the inside of the bearing and the intrusion of foreign matter from the atmosphere can be suppressed at the same time.

[0090] The front end 15c of the lip 15 is in an arc shape with a radius of 0.03 to 0.09 mm. This can more reliably suppress changes in the surface pressure distribution of the lip 15 when the rolling bearing 1 rotates, and suppress undesired torque increase and undesired heating of the lip 15.

[0091] Since the surface roughness of the inner surface of the main lip 15 and the like is Ra=0.4 to 2.5 μm, the desired dust emission suppression effect can be achieved and the resistance to grease can be suppressed to a low level.

[0092] The outer peripheral portion of the sealing member 6 is provided with an air outlet 12 for releasing the internal pressure of the rolling bearing 1. Therefore, when the rolling bearing 1 rotates, by releasing the internal pressure of the bearing from the air outlet 12, it is possible to suppress excessive changes in the seal interference and the outflow of grease due to the increase in the internal pressure of the bearing. The radial air outlet 12a and the axial air outlet 12b are arranged at different circumferential positions. By staggering the circumferential positions of the radial air outlet 12a and the axial air outlet 12b, i.e., the circumferential phase, the outflow of grease can be more reliably suppressed.

[0093] <Other Implementations>

[0094] In the following description, the same reference symbols are used for the parts corresponding to the matters previously described in each embodiment, and repeated descriptions are omitted. When only a part of the composition is described, unless otherwise specified, the other parts of the composition should be the same as the form described previously. The same composition can achieve the same effect. Not only can the parts specifically described in each embodiment be combined, but also the embodiments implemented can be partially combined if there is no special combination obstacle.

[0095] like Fig. 7A and Figure 7B As shown in FIG. 1 , the auxiliary lip portions 16a and 16b of the sealing member 6A can be arranged at two parallel positions spaced apart in the radial direction, and a grease reservoir 17 can be arranged between the two auxiliary lip portions 16a and 16b. Grease is stored in the grease reservoir 17. The auxiliary lip portion 16a on one side protrudes axially inward from the inner side surface portion of the base end portion 15a of the main lip portion 15. The auxiliary lip portion 16b on the other side protrudes axially inward from the inner side surface portion of the lip main body portion 15b of the main lip portion 15. In addition, the lip main body portion 15b in this example is connected to the inner diameter side end of the base end portion 15a, and is inclined inward as it extends axially outward.

[0096] Again, if Figure 8 As shown, the front end portion 15c of the main lip portion 15 constituting the contact portion with the seal groove is formed in such a manner that the ratio of the axial dimension L2 to the radial dimension L3 of the rounded shape is 50%±10%.

[0097] The wall thickness of the portion A1 in the base end portion 15 a of the main lip portion 15 and the length of the portion B1 of the lip body portion, which are related to the surface pressure, are set as follows.

[0098] *A1 wall thickness: 80% ± 10% of the core iron thickness t

[0099] *B1 section length: radial length of the inner peripheral portion of the seal member (rubber section) 50% ± 10% of the wall thickness of C1 section.

[0100] The dimensions of other parts are set as follows.

[0101] The wall thickness of the D1 portion of the auxiliary lip portion located on the inner diameter side, the axial length of the E1 portion, and the setting position F1 are set as follows.

[0102] *D1 wall thickness: 15% ± 5% of the radial length C1 of the rubber section.

[0103] *Axial length of E1: 180% ± 10% of the core iron thickness t

[0104] * Setting position F1: The position at 70%±5% of the inner diameter of the core metal relative to the radial length C of the cross section of the rubber portion.

[0105] <FEM Analysis Results of Contact State and Surface Pressure Change of Sealing Member 6A>

[0106] Fig. 9A It is an enlarged cross-sectional view showing the contact state between the sealing member 6A and the sealing groove 7 . Fig. 9B This is a diagram showing the surface pressure distribution when the interference of the sealing component is minimum. Fig. 9C Graph showing the surface pressure distribution when the interference of the sealing component is maximum. Fig. 9B , Fig. 9C Each vertical axis in the figure represents the surface pressure of the lip of the sealing component (unit: kgf / mm 2 ), each horizontal axis represents the coordinate (unit: mm) of the outer diameter side inclination direction of the contact portion when the contact position between the front end portion 15c of the lip and the seal groove 7c on the inner diameter side is taken as the reference position (zero).

[0107] according to Fig. 9B , Fig. 9C The analytical results shown in the figure show that the surface pressure of the lip 15 changes little when the interference of the sealing member 6A is minimum and maximum. Fig.15A , Fig. 15B and Fig. 15C In the analysis results of the sealing member 56 of the conventional example shown in , when the interference of the sealing member 56 is the smallest ( Fig. 15B ) and maximum time ( Fig. 15C ), the surface pressure variation of the lip 57 becomes relatively large and is concentrated at one point, so it is not suitable.

[0108] According to this structure, the grease stored in the grease reservoir 17 can intercept the grease that contributes to lubrication and prevent it from flowing out, and can also prevent foreign matter from entering from the atmosphere. The same effects as those of the other above-mentioned embodiments can be achieved. In addition, the main lip 15 and the two auxiliary lips 16a and 16b as contact seal members can further improve the effect of preventing the grease from flowing out and the effect of preventing the foreign matter from entering.

[0109] like Fig.10 As shown, the main lip 15 may be provided with an air outlet 18 for releasing the internal pressure of the rolling bearing. In the front end portion 15c of the main lip 15, for example, a plurality of radial air outlets 18 are evenly distributed in the circumferential direction. Each air outlet 18 is constituted by a groove. The air outlet 18 and the outer groove wall surface 7c facing the air outlet 18 form a hole. In addition, the radial air outlet 18 in the front end portion 15c of the main lip 15 may be one. In addition, the plurality of radial air outlets 18 may also be unevenly distributed in the circumferential direction.

[0110] according to Fig.10 With the structure, when the rolling bearing rotates, the bearing internal pressure is released from the air outlet 18, thereby suppressing the outflow of grease due to excessive changes in the seal interference and the increase in the bearing internal pressure.

[0111] like Fig.11 As shown, the sealing component 6 can be installed only on one side of the inner circumference of the outer ring in the axial direction. In this case, the bearing internal pressure can be prevented from increasing excessively when the rolling bearing rotates, and the number of parts can be reduced to reduce costs. In addition, either or both of the inner and outer rings 2 and 3 can be provided with a sealing groove and a sealing component fixing groove.

[0112] like Fig.12 As shown, in the resin corrugated retainer, the inner diameter side of the retainer may have a grease receiving portion 19 that can accommodate grease. The retainer 5A is provided with a grease receiving portion 19 on the inner diameter surface of the bag wall portion 5c, and the grease receiving portion 19 is a cutout portion. The grease receiving portion 19 is configured as a curved surface shape, and is configured as a concave curve in which a part of the inner diameter surface of the bag wall portion 5c is cut away. The grease receiving portion 19 is formed during the injection molding of the annular body 5a, but can also be formed by additional processing after the injection molding. According to the rolling bearing having the retainer 5A with such a grease receiving portion 19, when the bearing is running, the grease accumulated in the stationary space is contained in the grease receiving portion 19 under the action of centrifugal force, and is further supplied to the track surface. As a result, the grease life can be extended compared to the rolling bearing having a retainer without a grease receiving portion.

[0113] In each embodiment, a resin corrugated cage is used as the cage, but a so-called iron plate corrugated cage may be used.

[0114] Furthermore, the retainer may be a so-called crown-type retainer in which pockets are provided at a plurality of positions in the circumferential direction of the annular body, the balls are retained inside the pockets, and one axial side of the pockets is open.

[0115] As described above, although the preferred embodiments have been described with reference to the drawings, various additions, changes, or deletions may be made without departing from the gist of the present invention. Therefore, these are also included in the scope of the present invention.

[0116] [Explanation of symbols]

[0117] 1...Rolling bearings

[0118] 2...Inner ring

[0119] 3...Outer ring

[0120] 4...Ball

[0121] 5.5A...Retainer

[0122] 6, 6A...Sealing parts

[0123] 7...Seal groove

[0124] 7c...Outer groove wall

[0125] 12...Air outlet

[0126] 12a...Radial air outlet

[0127] 12b...Axial air outlet

[0128] 15...Lips

[0129] 15c...Front end

[0130] 16a, 16b...secondary lip

[0131] 17...Grease reservoir

[0132] 18...Air outlet

[0133] 19...Grease storage section.

Claims

1. A rolling bearing, in which a plurality of balls sandwiched between an inner ring and an outer ring are held in a retainer, a sealing member is mounted on the outer ring for sealing a bearing space between the inner ring and the outer ring, and a sealing groove is formed in a circumferential direction on an outer peripheral surface of the inner ring, characterized in that: The above-mentioned sealing component is a contact sealing component, which contacts the above-mentioned sealing groove with the outer side of the lip portion. The outer groove wall surface of the above-mentioned sealing groove is formed as an inclined surface, and the inclined surface is inclined toward the outer diameter side as it extends axially outward. The inclination angle of the above-mentioned outer groove wall surface relative to the axial direction is 55~65°, and the front end portion of the above-mentioned lip portion has a rounded lip shape that contacts the above-mentioned outer groove wall surface at 80~100°.

2. The rolling bearing according to claim 1, characterized in that: The front end portion of the lip portion is in an arc shape with a radius of 0.03 to 0.09 mm.

3. The rolling bearing according to claim 1 or 2, characterized in that: The sealing member has a core iron and a rubber material. The lip portion is made of the rubber material. On the inner side surface of the lip portion, a part or all of the part located on the inner diameter side of the PCD has a surface roughness of Ra=0.4 to 2.5 μm.

4. The rolling bearing according to claim 1 or 2, characterized in that: An air outlet for releasing the internal pressure of the rolling bearing is provided on the outer diameter portion of the sealing member.

5. The rolling bearing according to claim 4, characterized in that: The outer peripheral side portion of the sealing component on at least one side is provided with a plurality of the air outlets, which include radial air outlets formed along the radial direction and axial air outlets formed along the axial direction, and the radial air outlets and the axial air outlets are arranged at different circumferential positions.

6. The rolling bearing according to claim 1 or 2, characterized in that: An air outlet for releasing the internal pressure of the rolling bearing is provided on the lip portion of the sealing member.

7. The rolling bearing according to claim 4, characterized in that: The air outlet provided on the sealing component is located on one or both sides of the sealing component in the axial direction.

8. The rolling bearing according to claim 1 or 2, characterized in that: The sealing member includes an auxiliary lip portion protruding axially inward from a base end portion, and a labyrinth seal is formed between a front end portion of the auxiliary lip portion and an inner groove wall surface of the seal groove.

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