WO2022202544A1

WO2022202544A1 - Seal-equipped bearing

Info

Publication number: WO2022202544A1
Application number: PCT/JP2022/011933
Authority: WO
Inventors: 克明佐々木; 悠介鈴木; 雄太望月; 吉稀竹田; 武仁櫻井
Original assignee: Ntn株式会社
Priority date: 2021-03-24
Filing date: 2022-03-16
Publication date: 2022-09-29
Also published as: JP2022148225A

Abstract

The present invention suppresses the intrusion of foreign matter into the interior of a bearing in a seal-equipped bearing in which, due to a plurality of protrusions in a seal lip, a fluid lubrication condition can be created between the seal lip and a seal sliding surface. As a means therefor, the protrusions (12) extend in a diagonal direction such that lubricating oil in gaps (13) between the protrusions (12) is pressurized in the direction of exiting to the exterior, in conjunction with the rotation of the bearing. Alternatively, the seal lip has ribs that are positioned out of phase with the plurality of protrusions so as to face the gaps, and are positioned with a space between the ribs and the seal sliding surface. Alternatively, protrusions that are neighboring in the circumferential direction extend in directions that are slanted with regard to the circumferential direction, in directions opposing one another.

Description

Sealed bearing

The present invention relates to a sealed bearing comprising a rolling bearing and a sealing member.

A seal member is used to prevent early damage to the rolling bearing. For example, in transmissions mounted on vehicles such as automobiles and various construction machines, foreign matter such as wear powder of gears is mixed, so a seal member prevents the wear powder from entering the inside of the bearing.

Generally, the sealing member has a ring-shaped sealing lip made of a rubber-like material or the like. A mating part such as a bearing ring, a slinger, or the like, which rotates relative to the seal member in the circumferential direction as the bearing rotates, is formed with a seal sliding surface that makes sliding contact with the seal lip.

In general seal members, the seal lip and the seal sliding surface are in sliding contact all around, and microscopically, there is a solid contact area. The drag resistance (seal torque) of the seal lip causes an increase in bearing torque. Moreover, the sliding contact contributes to the temperature rise of the rolling bearing. In addition, since the inside of the bearing is closed off from the outside by the seal member, the pressure difference between the inside and the outside of the bearing causes the seal lip to press against the seal sliding surface, causing an adsorption effect, which may increase the seal torque. For these reasons, there is a limit to the high-speed operation of bearings with common sealing members.

If the seal lip of the seal member is arranged so as not to contact the mating part and forms a labyrinth seal, it is possible to eliminate the seal torque. It is difficult to manage various errors that can be prevented.

On the other hand, the seal lip has a plurality of projections arranged in the circumferential direction. A seal-equipped bearing has been proposed in which the seal lip and the seal sliding surface can be brought into a fluid lubrication state by an oil film of lubricating oil that is dragged between the projection and the seal sliding surface through the gap (Patent Document 1). .

In the bearing with seal of Patent Document 1, lubrication on the seal sliding surface is achieved by allowing lubricating oil to flow between the internal space and the outside of the rolling bearing through a gap that can prevent foreign matter of a predetermined particle size from entering. Lubricating with oil, the wedge effect when lubricating oil is drawn between the projections and the seal sliding surface as the bearing rotates forms a thick oil film, completely separating each projection and the seal sliding surface with the oil film. , a fluid lubricating state can be established between the seal lip and the seal sliding surface. Therefore, according to the sealed bearing of Patent Document 1, the seal torque can be significantly reduced while preventing the intrusion of foreign matter of a predetermined particle size and enabling the bearing to operate at high speed.

WO2016/143786

However, since the seal lip of Patent Document 1 has only one row of a large number of projections extending straight in the radial direction, gaps generated between adjacent projections in the circumferential direction communicate linearly between the inside and outside of the bearing. Foreign matter with a particle diameter smaller than the cross-sectional height of the passage of the gap is likely to flow straight through the gap and enter the bearing. Even the above-mentioned small foreign matters may cause peeling and surface roughness of the raceway surface due to the small foreign matters if they enter the inside of the bearing in large amounts, leading to deterioration of sound and generation of vibration. For this reason, it is preferable to prevent even small foreign matter from entering the bearing.

In view of the background described above, the problem to be solved by the present invention is to provide a sealed bearing in which a plurality of protrusions on the seal lip allow fluid lubrication between the seal lip and the seal sliding surface. It is to suppress the intrusion of foreign matter.

As a first means for achieving the above object, the present invention provides a seal member for sealing the internal space of a rolling bearing from the outside, and a seal sliding surface that slides in the circumferential direction against the seal member. wherein the seal member has a ring-shaped seal lip, the seal lip has a plurality of projections arranged in a circumferential direction, and the plurality of projections are adjacent to each other in the circumferential direction The seal lip and the seal are separated from each other by an oil film of lubricating oil that is drawn between the protrusion and the seal sliding surface through the gap as the bearing rotates. In the sealed bearing formed in such a manner that the sliding surfaces can be fluidly lubricated, the protrusions are configured to extend in a direction inclined to one side in the circumferential direction toward the outside. .

According to the above first means, in the sealed bearing in which the seal lip and the seal sliding surface can be brought into a state of fluid lubrication by the plurality of projections of the seal lip, the projections extend outward in the circumferential direction. Since it extends in a direction inclined to the side, it is arranged in a threaded manner around the seal sliding surface. Therefore, when using a bearing with a seal, if the rotation direction of the bearing is selected so that the projections pressurize the lubricating oil in the clearance to the outside as the bearing rotates, the projections and the seal sliding surface will prevent Since a screw pumping action is provided to prevent foreign matter from entering the bearing, entry of foreign matter into the bearing can be suppressed.

For example, the protrusion is formed in a straight line that is inclined with respect to the radial direction.

Preferably, the projection is formed in a curved shape that curves to one side in the circumferential direction. In this way, the projections are longer than the linearly formed projections, so the pressure loss of the lubricating oil flow in the gaps is increased (labyrinth effect), and the intrusion of foreign matter can be further suppressed. .

As a second means for achieving the above object, the present invention provides a seal member that seals the internal space of a rolling bearing from the outside, and a seal sliding surface that rotates relative to the seal member in the circumferential direction. wherein the seal member has a ring-shaped seal lip, the seal lip has a plurality of projections arranged in a circumferential direction, and the plurality of projections are adjacent to each other in the circumferential direction The seal lip and the seal are separated from each other by an oil film of lubricating oil that is drawn between the protrusion and the seal sliding surface through the gap as the bearing rotates. In a bearing with a seal formed in such a manner that a fluid lubricating state can be established between sliding surfaces, the seal lip is arranged out of phase with the plurality of projections so as to face the gap, and the A structure having ribs spaced apart from the seal sliding surface was adopted.

According to the second means, it is possible to bring the seal lip and the seal sliding surface into a fluid lubrication state by means of the plurality of projections of the seal lip as the bearing rotates. Since the ribs face the gaps out of phase with the plurality of protrusions, a labyrinth in which part of the lubricating oil flowing out from the gaps into the internal space collides with the ribs is formed together with the protrusions adjacent in the circumferential direction. By forming it, it is possible to suppress the entry of foreign matter into the bearing. Since the ribs are spaced apart from the seal sliding surface, they are not in contact with the seal sliding surface. resistance does not increase. This avoids the ribs from adversely affecting seal torque reduction.

For example, the protrusion and the rib each extend linearly in a direction perpendicular to the circumferential direction.

Preferably, the protrusion and the rib are each hemispherical. By doing so, it is possible to suppress the shear resistance of the lubricating oil between the seal sliding surface and the linear projections or ribs.

As a third means for achieving the above object, the present invention provides a seal member for sealing the internal space of a rolling bearing against the outside, and a seal sliding surface that rotates relative to the seal member in the circumferential direction. wherein the seal member has a ring-shaped seal lip, the seal lip has a plurality of projections arranged in a circumferential direction, and the plurality of projections are adjacent to each other in the circumferential direction The seal lip and the seal are separated from each other by an oil film of lubricating oil that is drawn between the protrusion and the seal sliding surface through the gap as the bearing rotates. In the bearing with a seal formed in such a manner that the sliding surfaces can be fluidly lubricated, the protrusions adjacent to each other in the circumferential direction extend in opposite directions in the circumferential direction. adopted the configuration.

According to the third means, it is possible to bring the seal lip and the seal sliding surface into a state of fluid lubrication by means of the plurality of projections of the seal lip as the bearing rotates. Since the protrusions adjacent to each other in the circumferential direction extend in opposite directions to each other in the circumferential direction, it is possible to reduce the gap serving as a path for foreign matter to enter, thereby suppressing foreign matter from entering the bearing.

Specifically, among the plurality of projections, a first projection extending in a direction inclined to one side in the circumferential direction, and a direction adjacent to the other side in the circumferential direction of the first projection and inclined to the other side in the circumferential direction It is preferable that the second protrusions extending to the inner space are continuous with each other at the ends on the inner space side. By doing so, the mold transfer surfaces for molding the pair of first projections and second projections can be processed in series, and the processing cost can be suppressed.

In each of the above first to third means, the projection has a streamlined end positioned closer to the internal space than the sliding portion with the seal sliding surface, and the streamlined end is: It is preferable that the protrusion has a shape in which the circumferential width and height of the protrusion gradually decrease toward the inner space side. With this configuration, the streamlined end of the projection prevents the lubricating oil flowing through the gap along the projection toward the internal space from becoming turbulent, which is suitable for reducing the stirring resistance of the lubricating oil.

Further, in each of the first to third means, the angle α formed by the seal lip and the seal sliding surface toward the inner space side from the sliding portion of the protrusion and the seal sliding surface is , 0°<α≦45°. In this way, a pumping action can be generated to discharge the lubricating oil to the outside in the region where the angle α between the seal lip and the seal sliding surface is formed. suitable for reducing

Further, in each of the first to third means, the combined roughness σ of the protrusion and the seal sliding surface is preferably 0.9 μm or less. This is suitable for bringing the sliding portion between the protrusion and the seal sliding surface into a fluid lubrication state from an extremely low peripheral speed.

According to the present invention, by adopting a configuration relating to at least one of the above first to third means, a plurality of projections on the seal lip provide fluid lubrication between the seal lip and the seal sliding surface. Entry of foreign matter into the bearing can be suppressed in a sealed bearing capable of

1 is a cross-sectional view showing a sealed bearing according to a first embodiment of the present invention; FIG. 2 is a partial sectional view showing the natural state of the seal lip of FIG. 1; Enlarged left side view near the protrusion in FIG. Enlarged view of the vicinity of the protrusion in Fig. 1 Enlarged right side view near the gap in Fig. 1 Sectional view of the VI-VI cutting line of FIG. FIG. 3 is a left side view of a seal lip according to a second embodiment of the invention, similar to FIG. FIG. 7 is a cross-sectional view similar to FIG. 6 showing the gap according to the second embodiment of the present invention; FIG. 6 is a right side view similar to FIG. 5 showing the vicinity of the gap according to the second embodiment of the present invention; FIG. 4 is a plan development view showing a projection according to a third embodiment of the present invention; The perspective view of the protrusion which concerns on 3rd embodiment of this invention FIG. 14 is a cross-sectional view showing the seal lip according to the fourth embodiment of the present invention along the line XII-XII in FIG. 14; The left side view showing the seal lip according to the fourth embodiment in the same manner as in FIG. Cross-sectional view of the XIV-XIV section line along the length direction of the protrusion shown in FIG. FIG. 5 is a cross-sectional view similar to FIG. 4 showing a seal lip according to a fifth embodiment of the present invention; Cross-sectional view of the XVI-XVI cutting line along the length direction of the protrusion shown in FIG. FIG. 5 is a cross-sectional view similar to FIG. 4 showing a seal lip according to a sixth embodiment of the present invention; Cross-sectional view of section line XVIII-XVIII along the length of the protrusion shown in FIG. The left side view which shows the seal lip which concerns on 6th embodiment similarly to FIG. A perspective view of an electric vertical take-off and landing aircraft equipped with the sealed bearing of the present invention. Partial cross-sectional view of the motor in the drive unit of the electric vertical take-off and landing aircraft shown in FIG.

As an example of the invention according to the first means, a sealed bearing according to the first embodiment will be described with reference to FIGS. 1 to 6 of the accompanying drawings.

　This sealed bearing shown in FIG.

The rolling bearing 1 is composed of an inner ring 3, an outer ring 4, a plurality of rolling elements 5 interposed between the inner ring 3 and the outer ring 4, and a retainer 6 that holds the plurality of rolling elements 5. The sealing member 2 seals the inner space 7 of the rolling bearing 1 from the outside. The purpose of this sealing is to prevent foreign matter from entering the inner space 7 between the inner and

outer rings

3 and 4, which is the periphery of the sealed bearing, and prevent early damage to the rolling bearing 1. It is not to seal the space 7 in a liquid-tight manner.

The inner ring 3 and outer ring 4 have raceway surfaces corresponding to the rolling elements 5 . The inner ring 3 is attached to the rotating shaft S and rotates together with the rotating shaft S. The outer ring 4 is attached to a member such as a housing, a gear, or the like that applies a load from the rotating shaft. The rolling elements 5 revolve while being interposed between the inner ring 3 and the outer ring 4 .

A ball is adopted as the rolling element 5. This sealed bearing is a deep groove ball bearing.

The internal space 7 is lubricated with lubricating oil (not shown; hereinafter the same) supplied from the outside. Lubricating methods include, for example, a splashing method in which lubricating oil is applied to the bearing with a seal, and an oil bath method in which the lower portion of the bearing with a seal is immersed in an oil bath. An appropriate amount of grease may be filled in the internal space 7 as an initial lubricant.

The rotating shaft S is provided as a rotating part provided in any one of, for example, a vehicle transmission, differential, constant velocity joint, propeller shaft, turbocharger, machine tool, wind power generator, and wheel bearing.

In addition, hereinafter, the direction along the bearing center axis (not shown, hereinafter the same) of the bearing with seal will be referred to as the "axial direction". A direction orthogonal to the axial direction is called a “radial direction”. The circumferential direction around the bearing center axis is called the “circumferential direction”. In the illustrated example, the bearing center axis is the center axis of the inner ring 3 which is a rotating ring, and corresponds to the left-right direction in the figure.

A seal groove 8 for holding the seal member 2 is formed at the end of the inner circumference of the outer ring 4 . The seal member 2 is attached to the outer ring 4 by press-fitting its outer peripheral edge into the seal groove 8 .

　Externally surrounding this sealed bearing, there are foreign matter depending on where this sealed bearing is installed, such as gear wear powder, clutch wear powder, fine crushed stones, etc. Such powdery foreign matter can reach the vicinity of the seal member 2 due to the flow of lubricating oil or atmosphere. The sealing member 2 is for preventing foreign matter from entering the internal space 7 from the outside.

The sealing member 2 has a core metal 9 made of a metal plate and a seal lip 10 formed in an annular shape. The cored bar 9 is a press-worked part that is annularly formed and continues in the circumferential direction. The seal lip 10 is made of vulcanized rubber. Examples of rubber materials include nitrile rubber (NBR), acrylic rubber (ACM), and fluororubber (FKM).

A seal sliding surface 11 that slides on the seal lip 10 in the circumferential direction is formed on the outer circumference of the inner ring 3 . The seal sliding surface 11 is in the shape of a cylindrical surface that continues along the entire circumferential direction.

The seal lip 10 is a radial lip. Here, the radial lip is a seal lip that exerts a sealing action with a seal sliding surface along the axial direction or a seal sliding surface having an acute angle gradient of 45° or less with respect to the axial direction. It has a radial interference between it and the moving surface.

FIG. 2 shows the cross-sectional shape (shape at the time of molding) when the seal lip 10 is in a natural state by itself. The seal lip 10 has an annular waist portion which is radially continuous with a constant width in the axial direction, and a head portion which is shaped like a projecting piece that curves outward from the waist portion.

The head of the seal lip 10 has a leading edge that defines the inner diameter of the seal lip 10 in the state of FIG. 1, the seal lip 10 is pressed against the seal sliding surface 11 due to the interference with the seal sliding surface 11, and deforms rubber-like elastically to the outside. , produces a straining force of the seal lip 10 . Mounting errors, manufacturing errors, etc. of the seal member 2 are absorbed by changes in the degree of bending of the seal lip 10 .

FIG. 3 shows an enlarged left side view of the vicinity of the head portion of the seal lip 10 in FIG. FIG. 4 shows an enlarged view of the vicinity of the head portion of the seal lip 10 of FIG. FIG. 5 shows an enlarged view of the gap 13 viewed axially from the outside. FIG. 6 shows a section taken along line VI-VI of FIG.

As shown in FIGS. 3 to 5, the seal lip 10 has a plurality of projections 12 arranged in the circumferential direction.

As shown in FIG. 3, the projection 12 is formed in a straight line inclined with respect to the radial direction of the seal lip 10 over its entire length. The direction of inclination of the projection 12 is set in a direction inclined to one side in the circumferential direction from the outer diameter side to the inner diameter side of the seal lip 10 (corresponding to a straight line direction inclined leftward downward in the figure). ing. The height of the protrusion 12 is constant over its entire length. Each protrusion 12 is located in a line with a fixed pitch in the circumferential direction. The entire length of the protrusion 12 extends over the entire range with a radial interference between the protrusion 12 and the seal sliding surface 11 . The sealing lip 10 has only one row of protrusions 12 . The overall shape of the seal lip 10 is rotationally symmetrical corresponding to the pitch of the protrusions 12 .

　When the seal member 2 is attached to the rolling bearing 1 as shown in FIG. The protrusion 12 has a height in a direction perpendicular to the seal sliding surface 11 on a virtual plane including the bearing center axis. The protrusion 12 stretches against the straining force of the seal lip 10. - 特許庁As a result, as shown in FIGS. 4 to 6, a gap 13 communicating with the internal space 7 and the outside is generated between the protrusions 12 adjacent in the circumferential direction and between the seal sliding surface 11 and the seal lip 10. Let me. The channel cross-sectional height of the gap 13 corresponds to the radial distance between the seal sliding surface 11 and the lip portion connecting the protrusions 12 adjacent in the circumferential direction. The seal lip 10 slides on the seal sliding surface 11 only on the plurality of protrusions 12, and the lip portion connecting the protrusions 12 adjacent in the circumferential direction is kept in a non-contact state with the seal sliding surface 11. It's like

When the seal member 2 is attached to the rolling bearing 1 as shown in FIG. 1, the plurality of inclined projections 12 as shown in FIG. will be 6, the protrusion 12 is axially inclined from the inner space 7 side to the outer side in the circumferential direction (to the right in FIG. 6). (corresponding to the upward tilted direction). Therefore, if the rolling bearing 1 shown in FIG. The seal sliding surface 11 exerts a screw pumping action that prevents foreign matter from entering the bearing through the clearance 13 .

As shown in FIG. 5, the protrusion 12 has a shape such that it gradually moves away from the seal sliding surface 11 from the center portion in the circumferential direction of the protrusion 12 toward both sides in the circumferential direction. Therefore, the protrusion 12 forms a wedge-shaped gap with the seal sliding surface 11 that is large on the gap 13 side and small on the protrusion 12 side. In the illustrated example, each protrusion 12 has a semicircular shape on a cut surface along the circumferential direction.

In addition, as shown in FIG. 4, the protrusion 12 has a region generally along the seal sliding surface 11 on a virtual plane including the bearing center axis. This region has a width in the direction along the seal sliding surface 11 (corresponding to the axial direction in the illustrated example). Therefore, there is a wedge effect when the protrusion 12 and the seal sliding surface 11 slide along with the rotation of the bearing, that is, when the protrusion 12 drags the lubricating oil in the gap 13 in the circumferential direction between the seal sliding surface 11 and the protrusion 12. promotes the formation of an oil film, and the region in which the oil film is interposed between the projection 12 and the seal sliding surface 11 has a finite length L occurs in Such a sliding portion between the protrusion 12 and the seal sliding surface 11 is considered to occur in a contact elliptical shape based on Hertz's theory of elastic contact.

In the sliding portion between the projection 12 and the seal sliding surface 11, the shear resistance of the lubricating oil between the rounded projection 12 and the seal sliding surface 11 is suppressed as described above. Since the sharpness of the central portion is avoided to prevent the oil film from being cut off by the protrusion 12, the wedge effect effectively promotes the formation of the oil film. Therefore, when the peripheral speed of the relative rotation of the projection 12 and the seal sliding surface 11 becomes more than a certain value due to the rotation of the bearing, the oil film thickness between the projection 12 and the seal sliding surface 11 is , and each protrusion 12 and the seal sliding surface 11 are completely separated by an oil film, resulting in a fluid lubrication state. As a result, a fluid lubrication state in which the seal lip 10 and the seal sliding surface 11 are completely separated by an oil film can be achieved. In such a fluid lubrication state, the sealing torque of the seal member 2 can be reduced to the same level as that of a non-contact type seal, thereby suppressing the temperature rise of the sealed bearing and preventing the adsorption action of the seal lip 10. can. When the peripheral speed is less than a certain value after the bearing is stopped, microscopically, a boundary lubrication state or a mixed lubrication state including a solid contact area occurs.

For example, in applications that support rotating parts in vehicle transmissions, the sealed bearing is generally lubricated by an appropriate method such as splashing or an oil bath. Therefore, lubricating oil supplied from the outside exists around the seal lip 10 . The lubricating oil is also commonly used for other lubricating parts such as gears present in the transmission. The lubricating oil is circulated by an oil pump and filtered by an oil filter provided in the circulation path. If a large foreign matter with a grain size exceeding 0.05 mm enters the internal space 7, it is considered to have an adverse effect on the life of the bearing. By setting the height of the protrusion 12 to 0.07 mm or less, it is possible to create a gap 13 through which such a large foreign matter cannot easily pass. When the height of the projections 12 is 0.07 mm or less, for example, the distance between adjacent projections 12 in the circumferential direction is 0.3 mm or more and 2.6 mm or less, and the circumferential width of the projections 12 is 0.2 mm or more and 1.0 mm or less. Moreover, the radius of curvature of the surface of the projection 12 can be set in the range of 0.15 mm or more and less than 2.0 mm. In this example, when the oil temperature is 30 to 120° C. and the relative peripheral speed of the seal lip 10 and the seal sliding surface 11 is 0.2 m/s or more, the dimensionless number determined by Greenwood-Johnson is In the lubrication region diagram (Johnson chart) based on the viscous parameter gv and the elastic parameter ge, either the constant viscosity-rigid region (RI mode) or the constant viscosity-elastic region (EI mode, soft EHL) It is considered to be in the lubrication mode, that is, the fluid lubrication state described above.

When the above-mentioned interval is 2.6 mm, an oil film of approximately 3 μm is formed between the protrusion 12 and the seal sliding surface 11, and when the interval is smaller than 2.6 mm, the oil film tends to be thicker. be. Further, when the above-described interval is 2.6 mm or less, the bearing rotating torque tends to decrease (that is, the seal torque tends to decrease). If the above-described interval is less than 0.3 mm, it becomes difficult to process the transfer surface for forming the protrusions 12 on the mold with a ball end mill. Considering molding with a mold, it is preferable to set the aforementioned radius of curvature of the protrusion 12 to 0.15 mm or more and less than 2.0 mm. Since the circumferential width of the projections 12 correlates with the aforementioned radius of curvature, it is preferable to set the circumferential width of the projections 12 to 0.2 mm or more and 1.0 mm or less.

Here, if the oil film parameter Λ≧3, the lubrication mode of the sliding portion is considered to be fluid lubrication. The oil film parameter Λ is the ratio of the combined roughness σ to the minimum oil film thickness h on the sliding portion, where Λ=h/σ. The minimum oil film thickness h is obtained based on elastohydrodynamic lubrication theory. The combined roughness σ=√((Rq ₁ ² +Rq ₂ ² )/2). Rq ₁ is the root-mean-square roughness of the seal sliding surface 11 forming the aforementioned sliding portion. _Rq2 is the root-mean-square roughness of the surface of the projection 12, and the root-mean-square roughness is the value (μm) of the root-mean-square roughness Rq defined in JIS (B0601:2013).

The oil film parameter Λ depends on the synthetic roughness σ, and the smaller the synthetic roughness σ, the thicker the oil film can be. In order to keep the sliding portion between the protrusion 12 and the seal sliding surface 11 in a fluid lubrication state from the time when the peripheral speed is extremely low, it is preferable to set the combined roughness σ of the sliding portion to 0.9 μm or less. For example, under the calculation conditions of synthetic roughness σ of 0.9 μm, transmission oil (30 cst, 40° C.) as lubricating oil, ambient temperature of 20° C., and peripheral speed of 0.2 m/s, the oil lubrication mode by the Johnson chart was determined. However, the minimum oil film thickness h was 2.8 μm, the oil film parameter Λ was 3 or more, and the lubrication mode was the EI mode. Therefore, if the combined roughness σ of the protrusion 12 and the seal sliding surface 11 is 0.9 μm or less, it is expected that the bearing will reliably be in a fluid lubricating state in the actual usage range.

On the virtual plane shown in FIG. 4, the seal lip 10 moves from the sliding portion between the projection 12 and the seal sliding surface 11 toward the inner space 7 (in the illustrated example, toward the inner space 7 in the axial direction). and the seal sliding surface 11 form an angle α of 0°<α≦45°. A space region 7a forming an angle α in the internal space 7 is a wedge-shaped space that narrows toward the outside in the axial direction. The space area 7a opens toward the rolling elements 5 and the cage 6. As shown in FIG.

The inflow of lubricating oil into the internal space 7 is secured by the gap 13, but this is contrary to the improvement of the inflow of lubricating oil into the internal space 7, and the resistance ( The bearing torque increases due to agitation resistance). During the agitation, the lubricating oil is pushed from the rolling elements 5 and the retainer 6 and flows toward the wedge-shaped space region 7a. hydraulic pressure increases. Therefore, a pumping action is generated to discharge the lubricating oil that has been pushed aside into the space region 7a through the gap 13 to the outside. As a result, the lubricating oil can be discharged from the internal space 7 better, the stirring resistance is reduced, and the internal torque of the bearing is reduced. Therefore, it becomes possible to use the rolling bearing 1 with even lower torque.

If the angle α exceeds 45°, the straining force of the seal lip 10 is reduced, and the seal lip 10 becomes too easily separated from the seal sliding surface 11, which may reduce the sealing performance against foreign matter.

In this bearing with seal, as described above, the seal lip 10 and the seal sliding surface 11 can be in a state of fluid lubrication by the plurality of projections 12 of the seal lip 10, and the projections 12 are attached to the seal. Since the projections 12 extend in a direction inclined to one side in the circumferential direction toward the outer side of the bearing, when the bearing with seal is used, the projections 12 are pushed in the direction to release the lubricating oil in the clearance 13 to the outside as the bearing rotates. If the direction of rotation of the bearing is selected so as to apply pressure, the protrusions 12 and the seal sliding surface 11 provide a screw pumping action that prevents foreign matter from entering the bearing interior (internal space 7) through the gap 13. As a result, entry of foreign matter into the bearing can be suppressed.

In this bearing with seal, the seal lip 10 and the seal sliding surface 11 form an angle .alpha. is 0°<α≦45°, a pumping action for discharging the lubricating oil to the outside can be generated in the spatial region 7a forming the angle α. Therefore, this sealed bearing is suitable for promoting the discharge of lubricating oil from the internal space 7 and reducing the stirring resistance of the lubricating oil by the rolling elements 5 and the like.

In addition, in this bearing with seal, the combined roughness σ of the projection 12 and the seal sliding surface 11 is 0.9 μm or less, so that the sliding portion of the projection 12 and the seal sliding surface 11 can be moved even at extremely low peripheral speeds. Suitable for fluid lubrication.

The second embodiment will be described based on FIGS. 7 to 9 (hereinafter, refer to FIGS. 1 and 4 as appropriate). The second embodiment is another example of the invention according to the first means. It should be noted that the following description of each embodiment is limited to the points of difference from the first embodiment.

The protrusion 21 according to the second embodiment is formed in a curved shape that curves from the inner space 7 side to the outer side in the circumferential direction. For this reason, the protrusions 21 are longer than the protrusions of the first embodiment, and accordingly, the gaps 22 formed between the protrusions 21 adjacent in the circumferential direction are also the same as in FIG. As shown in the cross-sectional view corresponding to the line VI-VI, the gap is curved longer than the gap in the first embodiment. Therefore, in the sealed bearing according to the second embodiment, not only the protrusions 21 exhibit the screw pumping action, but also the pressure loss (labyrinth effect) of the flow of lubricating oil in the gap 22 is reduced compared to the first embodiment. By increasing the size, the intrusion of foreign matter can be further suppressed.

A third embodiment will be described based on FIGS. 10 and 11. FIG. The third embodiment is still another example of the invention according to the first means.

The protrusion 31 according to the third embodiment has a streamlined end portion 32 positioned closer to the internal space 7 than the sliding portion with the seal sliding surface 11 . The streamlined end portion 32 has a predetermined length from the end on the inner space 7 side of the entire length of the protrusion 31 , and has a shape in which the circumferential width and height of the protrusion 31 gradually decrease toward the inner space 7 side. The rest of the protrusion 31 other than the streamlined end 32 has a semicircular cross-section with constant circumferential width and height. This shape change of the streamlined end portion 32 with respect to the remaining portion prevents the lubricating oil flowing along the protrusion 31 in the gap 33 toward the internal space 7 from separating from the protrusion 31 until it passes through the protrusion 31 (gap 33). , to suppress turbulence. If this flow becomes turbulent and flows out from the gap 33 into the internal space 7, the rolling elements 5 and the retainer 6 are in contact with the turbulent flow and the stirring resistance increases, so it is preferable to suppress the turbulent flow.

The wedge effect between the projection 31 and the seal sliding surface 11 can be reduced by sharpening the region of the projection 31 that slides with the seal sliding surface 11 like a streamlined end portion 32. , which is not desirable.

Ideally, the streamlined end 32 should have a streamlined shape that does not become turbulent until it passes over the protrusion 31 at a typical speed of the lubricating oil flowing along the protrusion 31 toward the inner space 7 side. The shape of the streamlined end 32 can be determined, for example, based on Fuhrmann's streamlined body of revolution.

Thus, in the sealed bearing according to the third embodiment, the streamlined end portion 32 of the projection 31 prevents the lubricating oil flowing through the gap 33 along the projection 31 toward the internal space 7 from becoming turbulent. , the agitation resistance of the lubricating oil in the internal space 7 can be reduced as compared with the first embodiment.

A fourth embodiment will be described based on FIGS. 12 to 14. FIG. The fourth embodiment is an example of the invention according to the second means.

A seal lip 41 according to the fourth embodiment has ribs 44 facing gaps 43 between protrusions 42 adjacent in the circumferential direction.

The protrusions 42 and the ribs 44 each extend linearly in a direction orthogonal to the circumferential direction.

The protrusions 42 and ribs 44 are arranged at a constant pitch angle. Therefore, the rows of the protrusions 42 arranged in the circumferential direction and the rows of the ribs 44 arranged in the circumferential direction form two rows with a constant phase difference therebetween.

The rib 44 is located closer to the internal space 7 side than the protrusion 42 . The rib 44 is spaced apart from the seal sliding surface 11 . Sufficient oil permeability is ensured so that the protrusion 42 and the seal sliding surface 11 are in a state of fluid lubrication by the lubricating oil supplied to the gap 43 from the outside and the lubricating oil flowing out from the internal space 7 into the gap 43. is possible.

The rib 44 faces the gap 43 at its outer end 45 . The opposing direction is the length direction of the protrusion 42 (the length direction of the gap 43) on the above-described imaginary plane, the direction along the gap 43 and the seal sliding surface 11, and the axial direction in the illustrated example. . A space is formed between the end portion 45 of the rib 44 and the projection 42 .

Between the protrusions 42 adjacent in the circumferential direction and the rib 44 closest to the gap 43 between these protrusions 42, part of the lubricating oil flowing out from the gap 43 toward the internal space 7 collides with the end 45 of the rib 44. form a labyrinth. Therefore, the lubricating oil flowing out from the gap 43 to the inner space 7 side causes a pressure loss due to the collision, and foreign matter is less likely to enter the inner space 7 through the gap 43 .

In addition, foreign matter flowing into the lubricating oil is caught between the end 45 of the rib 44 and the nearest protrusion 42, the flow of the lubricating oil hitting the end 45 and rebounding, and the lubricating oil discharged from the internal space 7 to the outside. It is discharged to the outside by the flow of oil.

As described above, in the sealed bearing according to the fourth embodiment, the plurality of projections 42 of the seal lip 41 can provide fluid lubrication between the seal lip 41 and the seal sliding surface 11. Since the seal lip 41 has the plurality of projections 42 and the ribs 44 arranged out of phase with each other so as to face the gaps 43, the projections 42 adjacent in the circumferential direction and the ribs 44 form a labyrinth to form a bearing. Intrusion of foreign matter into the interior can be suppressed. As a result, since the labyrinth suppresses the flow of the external lubricating oil to the internal space 7, a reduction in stirring resistance can be expected.

Further, since the ribs 44 are spaced apart from the seal sliding surface 11, they are not in contact with the seal sliding surface 11, and the ribs 44 and the seal sliding surface 11 do not contact each other. The shear resistance of the lubricating oil does not increase between This prevents the ribs 44 from adversely affecting seal torque reduction.

In addition, the shape of the cut surface along the circumferential direction of the rib 44 is the same shape as the protrusion 42 . Therefore, even if the gap between the rib 44 and the seal sliding surface 11 disappears due to abnormal flexural deformation of the seal lip 41, the sliding portion between the rib 44 and the seal sliding surface 11 is in a fluid lubrication state. so there is no problem.

In the illustrated example, the rib 44 is formed discontinuously with the projection 42, but the rib may be formed continuously with the projection, or the rib may be formed as a connecting portion for connecting circumferentially adjacent projections in a series. .

A fifth embodiment will be described based on FIGS. 15 and 16. FIG. The fifth embodiment is another example of the invention according to the second means. Here, only changes from the fourth embodiment will be described.

The protrusions 51 and ribs 52 according to the fifth embodiment are hemispherical. Here, the hemispherical shape means that the surface forms a convex curved shape on the cut surface along the circumferential direction, and the surface also forms a convex curved shape on the cut surface perpendicular to the circumferential direction, and the convex curved shape is a circle. A solitary shape is also included, but it is not limited to a form in which half of a sphere protrudes. The hemispherical shape has a curvature capable of securing a Hertzian contact area necessary for achieving fluid lubrication at the sliding portion with the seal sliding surface 11 .

Since the hemispherical projection 51 has a shape that escapes from the seal sliding surface 11 compared to the projection formed in a straight line as in the fourth embodiment, the lubricating oil between the projection 51 and the seal sliding surface 11 can reduce the shear resistance of In addition, the hemispherical ribs 52 can suppress the shear resistance of the lubricating oil particularly on the outer side of the ribs 52 near the seal sliding surface 11 .

A sixth embodiment will be described based on FIGS. 17 to 19. FIG. The sixth embodiment is an example of the invention according to the third means.

As shown in FIGS. 17 and 18, among the plurality of

protrusions

62a and 62b of the seal lip 61 according to the sixth embodiment, the

protrusions

62a and 62b that are adjacent in the circumferential direction are inclined in opposite directions in the circumferential direction. extending in the direction of

As shown in FIG. 19, the

projections

62a and 62b have a substantially rectangular shape with rounded two corners on the seal sliding surface 11 side.

As shown in FIG. 18, among the plurality of

projections

62a and 62b, a first projection 62a extending in a direction inclined to one side in the circumferential direction and a first projection 62a adjacent to the other side in the circumferential direction of the first projection 62a and the other side in the circumferential direction The second protrusion 62b extending in a direction inclined to the side is continuous at an end portion 62c on the inner space 7 side. A pair of the first protrusion 62a and the second protrusion 62b extends in a V shape outward from the end 62c.

Since the first protrusion 62a and the second protrusion 62b extend in directions inclined in directions opposite to each other in the circumferential direction, the gap 63a formed by the pair is wide on the outside and narrow on the inner space 7 side. , the gap 63b between two pairs adjacent in the circumferential direction is narrow on the outside and wide on the inner space 7 side. Since the gap 63a formed by the pair of

projections

62a and 62b becomes narrower toward the internal space 7 side, part of the lubricating oil flowing toward the internal space 7 collides with the gap 63a, and as with the ribs described above, it is possible to prevent foreign matter from entering. can. Since the gap 63b is narrow on the outside, foreign matter does not particularly easily enter through the gap 63b.

In addition, the first projection 62a and the second projection 62b extend in directions inclined in directions opposite to each other in the circumferential direction, and the pair of the first projection 62a and the second projection 62b provide a wide range in the circumferential direction. Therefore, even if the number of

protrusions

62a and 62b arranged in the circumferential direction is reduced, that is, even if the number of

gaps

63a and 63b is reduced, the number of

protrusions

62a , 62b do not come into solid contact with the seal sliding surface 11 due to the tightening force, the rigidity of the seal lip 61 can be secured.

Thus, in the sealed bearing according to the sixth embodiment, the plurality of

projections

62a and 62b of the seal lip 61 can provide fluid lubrication between the seal lip 61 and the seal sliding surface 11. Since the first projection 62a and the second projection 62b, which are adjacent in the circumferential direction, extend in opposite directions in the circumferential direction, the

gaps

63a and 63b, which serve as paths for foreign matter to enter, are reduced to reduce the

gaps

63a and 63b. Intrusion of foreign matter into the interior can be suppressed.

Further, the bearing with seal according to the sixth embodiment has a plurality of

protrusions

62a and 62b, the first protrusion 62a extending in a direction inclined to one side in the circumferential direction, and the other side in the circumferential direction of the first protrusion 62a. Since the second projections 62b adjacent to each other and extending in a direction inclined to the other side in the circumferential direction are continuous with each other at the end portion 62c on the side of the internal space 7, the pair of the first projection 62a and the second projection 62b are connected to each other. The mold transfer surface for molding can be processed in series, and the processing cost can be suppressed.

Specifically, the mold transfer surface can be processed by cutting a series of grooves on the mold so as to draw a V-shaped trajectory with an end mill. A pair of the first projection and the second projection can be molded as discontinuous portions at the ends on the inner space side of each other. It is necessary to move the end mill up and down in order to switch between the cutting of the transfer surface for forming the second protrusion, which is disadvantageous in terms of processing cost.

In each of the above-described embodiments, an example in which the protrusions are arranged uniformly in the circumferential direction has been shown, but it is also possible to arrange them unevenly. Further, in the first, second, and sixth embodiments, it is possible to lengthen the sliding portion (region of finite length L) between the protrusion and the seal sliding surface, as in the fourth and fifth embodiments.

Further, in each of the above-described embodiments, the seal member is composed of a metal core and a vulcanized rubber material, but the present invention is applicable to a seal member formed of a single material such as a rubber material or a resin material. It is also possible to

Moreover, although the radial lip is illustrated in each of the above-described embodiments, the present invention is applied to a seal lip (axial lip) that exhibits a sealing action with a seal sliding surface having a gradient exceeding 45° with respect to the axial direction. It is also possible to

In addition, in each of the above-described embodiments, an inner ring rotating radial ball bearing was exemplified, but the present invention can also be applied to an appropriate type such as an outer ring rotating bearing, a thrust bearing, or a roller bearing. Also, although an example in which the seal sliding surface is formed on the rotating ring has been shown, it is also possible to apply the present invention when forming the seal sliding surface on the stationary ring.

Further, the streamlined end portion of the protrusion of the third embodiment can be applied to the protrusions of the above-described embodiments. It is possible to apply

Also, in recent years, flying cars, so-called flying cars, have attracted attention as a means of transportation that can replace cars. Flying cars are expected to solve the above social problems, and are expected to be used in various situations such as movement within and between regions, tourism and leisure, emergency medical care, and disaster relief.

As a flying car, a vertical take-off and landing aircraft (VTOL) attracts attention. Vertical take-off and landing aircraft can ascend and descend vertically between the sky and the takeoff and landing site, so they do not require a runway and are highly convenient. In recent years, in particular, electric vertical take-off and landing aircraft (eVTOL), which fly with batteries and motors, have become the mainstream of development due to social demands for reducing _CO2 emissions. Note that the concept of a vertical take-off and landing aircraft also includes those that do not have wheels.

As described above, the sealed bearing according to the present invention is suitable for high-speed rotation and excellent in low-torque characteristics (energy-saving operability). It is also suitable for parts. As an example, FIG. 20 shows an electric vertical take-off and landing aircraft equipped with a sealed bearing according to the present invention.

The electric vertical take-off and landing aircraft 101 shown in FIG. 20 is a multicopter having a main body 102 located in the center of the aircraft body and four drive units 103 arranged in the front, rear, left and right. The drive unit 103 is a device that generates lift and propulsion of the electric vertical take-off and landing aircraft 101 , and the electric vertical take-off and landing aircraft 101 flies by driving the drive unit 103 . The electric vertical take-off and landing aircraft 101 may have a plurality of driving units 103, and the number is not limited to four.

The body part 102 has a living space in which passengers (for example, about 1-2 people) can board. This living space is equipped with an operating system for determining the direction of travel and altitude, as well as instruments that indicate altitude, speed, flight position, and so on. Four arms 102a extend from the main body portion 102, and a driving portion 103 is provided at the tip of each arm 102a. In FIG. 20, the arm 102a is integrally provided with an annular portion that covers the rotating circumference of the rotor blade 104 in order to protect the rotor blade 104. As shown in FIG. A skid 102b is provided at the bottom of the main body 102 to support the aircraft during landing.

The drive unit 103 has a rotor blade 104 and a motor 105 that rotates the rotor blade 104 . In the drive unit 103, a pair of rotor blades 104 are provided on both sides of the motor 105 in the axial direction. Each rotor blade 104 has two blades extending radially outward.

The main body 102 is provided with a battery (not shown) and a control device (not shown). Controllers are also called flight controllers. Control of the electric vertical take-off and landing aircraft 101 is performed by the control device, for example, as follows. Based on the difference between the current attitude and the target attitude, the control device outputs a rotation speed change command to the motor 105 to adjust the lift force. Based on the command, an amplifier provided in motor 105 adjusts the amount of electric power sent from the battery to motor 105, and the rotation speed of motor 105 (and rotor blade 104) is changed. In addition, the adjustment of the number of rotations of the motors 105 is performed simultaneously for the plurality of motors 105, thereby determining the attitude of the aircraft.

FIG. 21 shows a partial cross-sectional view of the motor in the driving section. In FIG. 21, the above-described rotary blade is attached to one end side (upper side of the drawing) of the rotating shaft 107 of the motor 105, and the rotor is attached to the other end side (lower side of the drawing). The rotor is arranged opposite a stator fixed to the housing 106 and is rotatable relative to the stator. It should be noted that the motor 105 can employ a configuration of an outer rotor type brushless motor or an inner rotor type brushless motor.

The motor 105 includes a housing (device housing) 106, a rotor (not shown), a stator (not shown), an amplifier (not shown), and two rolling bearings 110,110. The housing 106 has an outer cylinder 106a and an inner cylinder 106b, between which a cooling medium flow path 106c is provided. Excessive temperature rise can be prevented by flowing the cooling medium through the flow path 106c. The material of the housing 106 is not particularly limited, and for example, an iron-based material, CFRP (carbon fiber reinforced plastic), or the like can be used.

Also, the rolling bearing 110 corresponds to any one of the first to sixth embodiments described above. Rolling bearing 110 rotatably supports rotating shaft 107 within housing 106 . The outer ring 111 of the rolling bearing 110 has the same outer diameter shape as the fitting portion on the inner periphery of the housing, and is directly fitted to the housing 106 without interposing a bearing housing or the like. An inner ring spacer 108 is inserted between the inner rings 112 of the rolling

bearings

110, 110, an outer ring spacer 109 is inserted between the outer rings 111, and preload is applied.

It should be noted that the bearing configuration in the driving portion is not limited to the configuration in FIG. In FIG. 21, the rotating shaft of the motor and the rotating shaft of the rotor blades are the same rotating shaft, but the rotating shaft of the motor and the rotating shaft of the rotor blades may be connected via a transmission mechanism. . In this case, the rolling bearing that supports the rotating shaft in the drive section may be the rolling bearing that supports the rotating shaft of the motor, or the rolling bearing that supports the rotating shaft of the rotor.

The embodiments disclosed this time should be considered illustrative in all respects and not restrictive. Therefore, the scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and scope of equivalents of the scope of the claims.

1, 110 Rolling bearing 2 Seal member 3

Inner ring

4, 111 Outer ring 5 Rolling element 6 Cage 7

Internal space

10, 41, 61 Seal lip 11

Seal sliding surface

12, 21, 31, 42, 51, 62a,

62b Projection

13 , 22, 33, 43, 53, 63a, 63b Gap 32

Streamline end portions

44, 52 Rib 62c End portion 101 Electric vertical take-off and landing aircraft 103 Drive unit 104 Rotary blade 105 Motor 107 Rotating shaft

Claims

A seal member that seals the internal space of the rolling bearing from the outside, and a seal sliding surface that slides in the circumferential direction against the seal member,
The seal member has a seal lip formed in an annular shape, the seal lip has a plurality of projections arranged in a circumferential direction, and the plurality of projections extend between the circumferentially adjacent projections. A gap that communicates with the internal space and the outside is generated, and an oil film of lubricating oil that is dragged from the gap between the protrusion and the seal sliding surface as the bearing rotates creates a gap between the seal lip and the seal sliding surface. In a sealed bearing that is formed in a manner that can be in a fluid lubricated state,
A bearing with a seal, wherein the protrusion extends in a direction inclined to one side in the circumferential direction toward the outside.
The sealed bearing according to claim 1, wherein the projection is formed in a straight line inclined with respect to the radial direction.
The bearing with seal according to claim 1, wherein the protrusion is formed in a curved shape that curves to one side in the circumferential direction.
A seal member that seals the internal space of the rolling bearing from the outside, and a seal sliding surface that rotates relative to the seal member in the circumferential direction,
The seal member has a seal lip formed in an annular shape, the seal lip has a plurality of projections arranged in a circumferential direction, and the plurality of projections extend between the circumferentially adjacent projections. A gap that communicates with the internal space and the outside is generated, and an oil film of lubricating oil that is dragged from the gap between the protrusion and the seal sliding surface as the bearing rotates creates a gap between the seal lip and the seal sliding surface. In a sealed bearing that is formed in a manner that can be in a fluid lubricated state,
The seal lip has a rib arranged out of phase with the plurality of projections so as to face the gap and arranged with a gap between the seal sliding surface and the seal lip. bearing.
The sealed bearing according to claim 4, wherein the protrusion and the rib each extend in a direction perpendicular to the circumferential direction.
The sealed bearing according to claim 4, wherein the protrusion and the rib are hemispherical.
A seal member that seals the internal space of the rolling bearing from the outside, and a seal sliding surface that rotates relative to the seal member in the circumferential direction,
The seal member has a seal lip formed in an annular shape, the seal lip has a plurality of projections arranged in a circumferential direction, and the plurality of projections extend between the circumferentially adjacent projections. A gap that communicates with the internal space and the outside is generated, and an oil film of lubricating oil that is dragged from the gap between the protrusion and the seal sliding surface as the bearing rotates creates a gap between the seal lip and the seal sliding surface. In a sealed bearing that is formed in a manner that can be in a fluid lubricated state,
A bearing with a seal, wherein the protrusions adjacent to each other in the circumferential direction extend in directions inclined in opposite directions in the circumferential direction.
Among the plurality of projections, a first projection extending in a direction inclined to one side in the circumferential direction, and a second projection adjacent to the other side in the circumferential direction of the first projection and extending in a direction inclined to the other side in the circumferential direction 8. The sealed bearing according to claim 7, wherein the protrusions are continuous at the ends on the inner space side.
The projection has a streamlined end portion positioned closer to the internal space than the sliding portion with the seal sliding surface, and the streamlined end portion extends toward the internal space side from the circumferential width and the width of the projection. 9. The sealed bearing according to any one of claims 1 to 8, which has a shape with gradually decreasing height.
10. An angle α formed by the seal lip and the seal sliding surface toward the inner space from the protrusion and the sliding portion of the seal sliding surface is 0°<α≦45°. The sealed bearing according to any one of Claims 1 to 3.
The bearing with seal according to any one of claims 1 to 10, wherein the combined roughness σ of the protrusion and the seal sliding surface is 0.9 µm or less.
12. A rotating part of any one of a vehicle transmission, differential, constant velocity joint, propeller shaft, turbocharger, machine tool, wind power generator and wheel bearing according to any one of claims 1 to 11. Sealed bearing.
It is mounted on an electric vertical take-off and landing aircraft that is equipped with a plurality of drive units having rotating blades and a motor that rotates the rotating blades, and that flies by rotating the rotating blades,
An inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a retainer for holding these rolling elements,
12. The sealed bearing according to any one of claims 1 to 11, which supports a rotating shaft in said driving portion.