Sealed ball bearing and bearing device

Abstract

To suppress deformation of a cage while preventing intrusion of foreign matter into an internal space of a bearing.SOLUTION: A sealed ball bearing which is used under an environment at a dmn value of 700,000 or more, comprises a seal member 20 capable of being brought into a fluid lubrication state, and a cage 10 is a crown-shaped cage containing engineering plastic. In the bearing: a dimensional relation between a diameter φx of a ball 5, a radius Ry of a radial-direction inner peripheral surface D of a pocket 11 in a cross-section which passes through a pocket center C of the pocket 11 and includes an axial center O of the bearing, and a radius Rz of a circumferential-direction inner peripheral surface E of the pocket 11 in a cross-section which, at the pocket center C, is orthogonal to a straight line in the bearing radius direction, which passes through the pocket center C, is φx<2Ry<2Rz; the circumferential-direction inner peripheral surface E comprises a first inner peripheral surface E1 on a base 12 side and a second inner peripheral surface E2 on a tip side; and a center C2 of the second inner peripheral surface E2 is further eccentric to the base 12 side than a center C1 of the first inner peripheral surface E1.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] This invention relates to a sealed ball bearing and a bearing device.

Background Art

[0002] For example, in various vehicles such as automobiles and construction machinery, and other various industrial machines, a large number of bearings are used on the motor shafts of speed changers (speed increasers and decreasers) equipped with drive motors. The bearings used in these devices are generally used under high-speed conditions compared to the bearings used for shaft support in general devices. Foreign substances such as wear powder of gears are mixed in the lubricating oil used in these devices. Therefore, by providing a seal member at the end of the bearing, the intrusion of foreign substances into the bearing is prevented to suppress the reduction of the bearing life, and the lubricating oil intrusion amount is suppressed to reduce the stirring resistance.

[0003] For example, in Patent Document 1, protrusions are provided on the seal lip provided on the seal member to create an oil passage communicating the inside and outside of the bearing, so that the space between the seal lip and the seal sliding surface is in a fluid lubrication state. Thereby, while suppressing the reduction of the bearing life due to wear powder of gears, etc., the fluid lubrication of the seal part is realized to reduce the seal torque.

[0004] Also, Patent Document 2 discloses a crown-shaped retainer having an annular base portion and a column portion protruding from the base portion, wherein the radial thickness of the crown-shaped retainer gradually becomes thinner from the base portion to the tip of the column portion, and the radial gap between the outer peripheral surface of the base portion and the inner peripheral surface of the shoulder of the outer ring is made larger than the radial gap between the inner peripheral surface of the base portion and the outer peripheral surface of the shoulder of the inner ring.

[0005] According to Patent Document 2, even when the lubricant scatters due to centrifugal force during high-speed rotation, the lubricant is retained between the outer peripheral surface of the base and the inner peripheral surface of the shoulder of the outer ring, thereby suppressing the inflow of the lubricant into the raceway surface of the outer ring. As a result, the stirring resistance is reduced, enabling reduction of torque and heat generation, and it is said that deformation of the cage due to centrifugal force during high-speed rotation can be suppressed.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] In Patent Document 1, it is possible to suppress a decrease in bearing life. However, in bearings used under high-speed conditions for supporting the motor shaft of a drive motor, under severe usage conditions beyond expectations, heat generation of the raceway ring due to interference with the cage and breakage of the cage are a concern.

[0008] Further, in Patent Document 2, measures are taken to prevent breakage of the cage under high-speed conditions. However, in this bearing, although seal members are provided at both axial ends of the bearing, since the seal members are non-contact seals, it is not possible to prevent the intrusion of foreign matter that affects the bearing life. For this reason, when this bearing is used in a device such as a transmission or a speed increaser / decreaser, there is a concern about a decrease in bearing life due to the intrusion of foreign matter into the bearing. In recent years, devices integrating a drive motor, an inverter, and a gear (such as a transmission) have been widely spreading. In such devices, oil lubrication is the mainstream, and bearings supporting the motor shaft of the drive motor also tend to be lubricated with the same oil as inside the transmission or the like. For this reason, there is a demand to more reliably prevent the intrusion of foreign matter into the bearing.

[0009] Therefore, an object of the present invention is to suppress deformation of a cage under high-speed conditions while preventing foreign matter from entering the bearing internal space.

Means for Solving the Problems

[0010] To solve the above problems, the present invention includes an inner ring, an outer ring, balls disposed between the inner ring and the outer ring, a cage having pockets for holding the balls along the circumferential direction, and a seal member that closes an opening at an axial end of a bearing internal space formed between the inner ring and the outer ring. dmn = {(D + d) / 2} × n D: Bearing outer diameter (mm) d: Bearing inner diameter (mm) n: Rotational speed (min -1 ) In a ball bearing used in an environment where the dmn value defined by is 700,000 or more, the seal member is fixed to one of the inner ring and the outer ring and has a seal lip that slidably contacts a seal sliding surface set on the other. The seal lip has a plurality of protrusions arranged in the circumferential direction. The plurality of protrusions create a gap between adjacent protrusions in the circumferential direction, and the gap allows a lubricating oil film drawn between the protrusions and the seal sliding surface during bearing rotation to bring the seal lip and the seal sliding surface into a fluid lubrication state. The cage is a crowned cage including an annular base and a plurality of column portions protruding in one direction from the base and containing engineering plastic. The dimensional relationship among the diameter φx of the ball, the radius Ry of the radially inner peripheral surface of the pocket in a cross section passing through the pocket center and including the bearing axis, and the radius Rz of the circumferentially inner peripheral surface of the pocket in a cross section perpendicular to the bearing radial line passing through the pocket center at the pocket center is φx < 2Ry < 2Rz. The circumferentially inner peripheral surface includes a first inner peripheral surface on the base side and a second inner peripheral surface on the tip side of the column portion rather than the first inner peripheral surface. The center of the second inner peripheral surface is eccentric toward the base side rather than the center of the first inner peripheral surface, and a ball bearing with a seal is adopted (Configuration 1).

[0011] In Configuration 1, the radius Rz of the circumferential-direction inner peripheral surface is the radius Rz of the first inner peripheral surface 1 and the radius Rz of the second inner peripheral surface 2 and a configuration in which they are set equal can be adopted (Configuration 2).

[0012] Further, in Configuration 1, a configuration in which a recess is provided as an oil reservoir between the first inner peripheral surface and the second inner peripheral surface can be adopted (Configuration 3).

[0013] Further, in Configuration 1, a configuration in which a single or a plurality of materials selected from nitrile rubber, acrylic rubber, and fluororubber are used for the seal lip can be adopted (Configuration 4).

[0014] Furthermore, in Configuration 1, when the supply of the lubricant to the bearing internal space is in one direction from one axial end side to the other axial end side, a configuration in which the seal member is provided only at the opening on one axial end side can be adopted (Configuration 5).

[0015] Also, a plurality of elements selected from the above Configurations 2 to 5 can be added to Configuration 1. That is, as elements added to Configuration 1, it can be Configuration 2 and 3, Configuration 2 and 4, Configuration 2 and 5, Configuration 2 and 3 and 4, Configuration 2 and 3 and 5, Configuration 2 and 4 and 5, Configuration 2 and 3 and 4 and 5, etc.

[0016] A bearing device can be adopted in which a rotating shaft included in a drive motor, a speed reducer, or a speed increaser for electric transportation equipment is supported by a sealed ball bearing composed of each of these aspects.

Advantages of the Invention

[0017] By adopting a seal member that can maintain a fluid lubrication state between the seal lip and the seal sliding surface, this invention aims to reduce the seal torque and control the inflow amount of lubricant into the bearing internal space. As a result, the stirring resistance of the lubricant within the bearing internal space is reduced, enabling the application of the bearing in a high-speed rotation range with a dmn value of 700,000 or more. At the same time, the intrusion of foreign matter of a size that can affect the bearing life can also be suppressed.

[0018] In addition, by adopting engineering plastic as the material of the crowned cage, optimizing the dimensional relationships of the diameter φx of the balls in the ball bearing, the radius Ry of the radially inner peripheral surface in the pocket of the cage, and the radius Rz of the circumferentially inner peripheral surface, and further offsetting the center of the second inner peripheral surface on the side far from the base of the circumferentially inner peripheral surface of the pocket toward the base side from the center of the first inner peripheral surface on the base side, the deformation of the cage during high-speed operation can be suppressed, and the entry of foreign matter between the cage and the seal member can be prevented.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7A

Figure 7B

Figure 8

Embodiments for Carrying Out the Invention

[0020] Embodiments of the present invention will be described with reference to the drawings. This embodiment is a rolling bearing 1 provided with a seal member 20 at an opening at an axial end of an inner space of the bearing.

[0021] As shown in FIGS. 1 to 3, the rolling bearing 1 includes an inner ring 3, an outer ring 4, a plurality of rolling elements 5 disposed between the inner ring 3 and the outer ring 4, and a cage 10 having pockets 11 that hold the rolling elements 5 along the circumferential direction. Since spherical bodies (steel balls) are adopted as the rolling elements 5, hereinafter, these will be referred to as balls 5. Further, this rolling bearing 1 will be hereinafter referred to as a sealed ball bearing 1 or simply as a bearing 1. Also, the direction along the bearing center axis of the bearing 1 is referred to as the "bearing axial direction" or simply the "axial direction", the direction orthogonal to the axial direction is referred to as the "bearing radial direction" or simply the "radial direction", and the circumferential direction around the bearing center axis is referred to as the "bearing circumferential direction" or simply the "circumferential direction".

[0022] The cage 10 is a crowned cage formed of engineering plastic. The cage 10 includes an annular base portion 12 and a plurality of column portions 13 protruding axially from the base portion 12. A pair of two column portions 13, 13 arranged in parallel along the circumferential direction are provided at regular intervals along the circumferential direction. The space between the pair of two column portions 13 constitutes a concave pocket 11. The outer diameter surface of the cage 10 is a curved surface (cylindrical surface) without a step. In the pocket 11 portion of the cage 10, the outer diameter surface and the inner diameter surface communicate with each other.

[0023] The tip of the column portion 13 forms a retaining claw 14. The retaining claws 14, 14 on both sides sandwiching the pocket 11 are curved in a direction approaching each other. Note that the adjacent column portions 13, 13 may be connected to each other between the adjacent pockets 11 in the circumferential direction. The balls 5 held by the pockets 11 revolve between the raceway surface 3a of the inner ring 3 and the raceway surface 4a of the outer ring 4 while being held by the pockets 11.

[0024] The inner ring 3 has a rotating shaft (not shown) fixed to its inner diameter portion 3b and rotates circumferentially integrally with the rotating shaft. The outer ring 4 is a member such as a housing or a gear (also not shown) and is attached to a fixing member that bears the load from the rotating shaft. As a result, the bearing 1 rotatably supports the rotating shaft with respect to the fixing member. Examples of the rotating shaft mentioned here include the rotating shaft of a drive motor provided in an electric transportation device such as an electric vehicle, or the rotating shaft of a speed reducer or a speed increaser provided in those electric transportation devices. Note that the bearing center axis of the bearing 1 and the rotation center axis of the rotating shaft are set coaxially.

[0025] At the time of assembling the bearing 1, an appropriate lubricant such as grease is enclosed in the bearing internal space A. Also, during use, lubricant (lubricating oil) is supplied from the outside into the bearing internal space A through the opening at one axial end side of the bearing internal space A. Further, the lubricant (lubricating oil) in the bearing internal space A flows out of the bearing internal space A through the opening at the other axial end side of the bearing internal space A. The bearing 1 is basically used under oil lubrication, and the grease enclosed as initial lubrication is subsequently replaced by the lubricating oil supplied from outside the bearing. When enclosing grease for initial lubrication, it is desirable to enclose grease in 5 to 20% of the total space volume in the bearing internal space A.

[0026] In the lubricating oil for lubricating devices such as a drive motor and a transmission, there are foreign matters such as wear powder of gears, wear powder of clutches, and other foreign matters corresponding to the devices where the bearing 1 is incorporated. It is desirable that these foreign matters are not suspended in the lubricating oil but are captured at some location. Also, the bearing 1 is lubricated with the same lubricating oil as these devices such as a drive motor and a transmission. For this reason, a seal member 20 is attached to the opening at the axial end of the bearing internal space A. In this embodiment, seal members 20 are provided at both axial ends of the bearing internal space A respectively.

[0027] The seal member 20 is composed of an annular member that covers the opening at the axial end of the bearing inner space A. The seal member 20 separates the bearing inner space A from the outside. Since foreign matter exists in the lubricating oil on the outside of the bearing with the seal member 20 interposed therebetween, the seal member 20 prevents these foreign matters from entering the bearing inner space A from the outside of the bearing.

[0028] As shown in FIG. 2, the seal member 20 includes a metal core 23 and an elastic portion 24 fixedly integrated with the core 23. The core 23 is an annular member formed in an L-shaped cross section over the entire circumference in the circumferential direction. In this embodiment, the core 23 is composed of a press-worked product. The elastic portion 24 is rubber and is vulcanized and adhered to the core 23. The vulcanization adhesion can be performed, for example, by placing the core 23 in a mold and vulcanizing and molding a vulcanized rubber material.

[0029] The elastic portion 24 of the seal member 20 includes a fitting portion 25 that protrudes radially outward on the outer diameter side, a main body portion 26 that covers the core 23, an overhanging portion 22 that protrudes from the main body portion 26 toward the inner diameter side, and a seal lip 21 that protrudes in a tongue shape radially inward at the tip of the overhanging portion 22. A seal groove 8 extending over the entire circumference is formed on the inner circumference of the axial end portion of the outer ring 4. The seal member 20 is fixed to the outer ring 4 by fitting the fitting portion 25 into the seal groove 8.

[0030] A seal sliding surface B that slides in the circumferential direction with respect to the seal lip 21 is formed on the outer circumference of the inner ring 3. The seal sliding surface B has a cylindrical surface shape extending over the entire circumference in the circumferential direction.

[0031] As shown in FIG. 6, the seal lip 21 has a waist portion 22 formed in an annular shape that is continuous in the radial direction with a constant width in the axial direction, and a head portion formed in a tab shape that bends from the waist portion 22 toward the outer side. A tightening margin is set between the head portion of the seal lip 21 and the seal sliding surface B. When the seal member 20 is attached to the predetermined arrangement shown in FIGS. 1 and 2, the seal lip 21 is pressed against the seal sliding surface B by the tightening margin, causing a rubber-like elastic deformation that bends outward in the axial direction, thereby generating the pressing force of the seal lip 21. The mounting error, manufacturing error, etc. of the seal member 20 are absorbed by the change in the deflection of the seal lip 21.

[0032] As shown in FIG. 7A, the seal lip 21 has a plurality of protrusions 27 arranged in parallel along the circumferential direction. The protrusions 27 extend in a direction orthogonal to the circumferential direction over their entire length and are arranged at uniform intervals over the entire circumference in the circumferential direction. Therefore, the gaps 28 formed between adjacent protrusions 27 in the circumferential direction are also formed at uniform intervals over the entire circumference in the circumferential direction. The gaps 28 form an oil passage that communicates the internal space A of the bearing with the outside of the bearing between the seal lip 21 and the seal sliding surface B.

[0033] Further, as shown in FIG. 7B, each of the protrusions 27 has a circumferential end portion 29 formed such that the distance from the seal sliding surface B increases toward both sides in the circumferential direction from the central portion of the circumferential width. That is, the protrusions 27 form a wedge-shaped gap that is large on the gap 28 side and small on the side close to the center p of the circumferential width of the protrusions 27 with respect to the seal sliding surface B.

[0034] As shown in Fig. 6, the protrusion 27 has a region generally along the seal sliding surface B on a virtual plane including the bearing center axis. This region exists with a width in the direction along the seal sliding surface B (corresponding to the left - right direction (axial direction) in Fig. 6). Therefore, due to the wedging effect when the protrusion 27 slides along the seal sliding surface B with the rotation of the bearing, that is, when the protrusion 27 draws the lubricating oil in the gap 28 into the wedge - shaped gap between the protrusion 27 and the seal sliding surface B in the circumferential direction, the formation of the oil film is promoted. The region where the oil film is interposed between the protrusion 27 and the seal sliding surface B occurs with a finite length of a predetermined value or more in the direction along the seal sliding surface B (axial direction) on the aforementioned virtual plane. Since such a sliding part between the protrusion 27 and the seal sliding surface B is considered to occur in an elliptical contact shape based on Hertz's elastic contact theory, the major axis of the elliptical contact shape corresponds to the aforementioned finite length.

[0035] When the circumferential speed of the relative rotation between the seal lip 21 and the seal sliding surface B is less than a certain value, microscopically, it is in a boundary lubrication state or a mixed lubrication state including a solid contact region. As the bearing rotation speed increases and the circumferential speed of the relative rotation between the protrusion 27 and the seal sliding surface B becomes a certain value or more, the oil film thickness between the protrusion 27 and the seal sliding surface B exceeds the composite roughness σ between the protrusion 27 and the seal sliding surface B with a margin, and a fluid lubrication state is achieved where each protrusion 27 and the seal sliding surface B are completely separated by the oil film. Thus, a fluid lubrication state where the seal lip 21 and the seal sliding surface B are completely separated by the oil film can be achieved. In such a fluid lubrication state, the seal torque by the seal member 20 can be reduced to the same level as that of a non - contact seal, and thus the temperature rise of the sealed bearing can be suppressed, and the adsorption effect of the seal lip 21 can be prevented.

[0036] Here, if the oil film parameter Λ≧3, the lubrication mode of the sliding part is considered to be in a fluid lubrication state. The oil film parameter Λ is the ratio of the minimum oil film thickness h 0 to the composite roughness σ, and Λ = h 0 / σ. The minimum oil film thickness h 0 is obtained based on the elastohydrodynamic lubrication theory. The composite roughness σ = √(Rq 1 2 +Rq 22 ) is Rq. 1 Rq is the root mean square roughness of the seal sliding surface B forming the aforementioned sliding portion. 2 When the root mean square roughness is that of the surface of the projection 27, the root mean square roughness is the value (μm) of the root mean square roughness Rq defined in JIS (B0601: 2013).

[0037] The oil film parameter Λ depends on the composite roughness σ, and the smaller the composite roughness σ, the thicker the oil film can be made. In order to bring the sliding portion between the projection 27 and the seal sliding surface B into a fluid lubrication state from the time when the circumferential speed is extremely low as described above, it is preferable to make the composite roughness σ in the sliding portion 0.9 μm or less. For example, when the composite roughness σ is 0.9 μm, the lubricating oil is mission oil (30 cst, 40 °C), the ambient temperature is 20 °C, and the circumferential speed is 0.2 m / s, when the oil lubrication mode is determined by the Johnson chart, the minimum oil film thickness h 0 is 2.8 μm, the oil film parameter Λ is 3 or more, and the lubrication mode becomes the E-I mode. Therefore, if the composite roughness σ between the projection 27 and the seal sliding surface B is 0.9 μm or less, it is expected that a fluid lubrication state will surely be achieved in the actual use area of the bearing.

[0038] For example, in applications for supporting rotating parts in a vehicle transmission, generally, mission oil is supplied as lubricating oil to the sealed bearing by an appropriate method such as splash or oil bath. The lubricating oil is circulated by an oil pump and filtered by an oil filter provided in the circulation path. If foreign matter larger than 0.05 mm in particle size enters the bearing internal space A, it is considered to have an adverse effect on the bearing life. If the protrusion height h (see FIG. 7B) of the projection 27 is set to 0.07 mm or less, a gap 28 can be created through which such large foreign matter cannot easily pass. In addition, in order to improve the oil permeability of the gap 28, it is desirable to set the protrusion height h of the projection 27 to 0.05 mm or more.

[0039] When the protrusion height h of the protrusion 27 is 0.07 mm or less, for example, the interval between adjacent protrusions 27 in the circumferential direction can be set in the range of 0.3 mm or more and 2.6 mm or less, the circumferential width of the protrusion 27 can be set in the range of 0.2 mm or more and 1.0 mm or less, and the radius of curvature of the surface of the protrusion 27 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 circumferential speed between the seal lip 21 and the seal sliding surface B is 0.2 m / s or more, computationally, in the lubrication region diagram (Johnson chart) based on the viscous parameter gv and the elastic parameter ge, which are dimensionless numbers determined by Greenwood-Johnson, it is considered to be in either the isoviscous-rigid body region (R-I mode) or the isoviscous-elastic body region (E-I mode, soft EHL), that is, the above-mentioned fluid lubrication state. When the interval between adjacent protrusions 27 in the circumferential direction is 2.6 mm as described above, an oil film of about 3 μm is formed between the protrusion 27 and the seal sliding surface B computationally, and the oil film tends to become thicker when it is smaller than 2.6 mm. When the above-mentioned interval is 2.6 mm or less, the bearing rotation torque tends to be low (that is, the seal torque tends to decrease). When the above-mentioned interval is less than 0.3 mm, it becomes difficult to form the transfer surface for forming the protrusion 27 on the mold by end milling.

[0040] As described above, by bringing the seal lip 21 and the seal sliding surface B into a fluid lubrication state, the friction (seal torque) caused by rubbing between the seal lip 21 and the seal sliding surface B can be made substantially close to zero, the seal lip 21 is substantially not worn, and heat generation due to sliding between the seal lip 21 and the seal sliding surface B can be suppressed. Furthermore, since the circumferential speed of the relative rotation allowed between the seal lip 21 and the seal sliding surface B becomes higher, operation under higher speed conditions than before becomes possible.

[0041] As the material of the seal lip 21, for example, a single or a plurality of materials selected from nitrile rubber, acrylic rubber, and fluororubber can be used. These materials may be used only for the seal lip 21 or for the entire elastic portion 24 including the seal lip 21.

[0042] The pocket 11 of the retainer 10 corresponds to the ball 5 with a diameter of φx. As shown in Fig. 3, the inner surface of the pocket 11 is an inner surface (spherical surface) that describes an arc along the bearing radial direction, and the radius in the bearing radial direction is set to Ry. 2Ry is twice Ry and corresponds to the diameter in the bearing radial direction of the inner surface of the pocket 11. That is, when the center of the pocket 11 is the pocket center C, the radius of the inner peripheral surface D (hereinafter referred to as the radial inner peripheral surface D) of the pocket 11 in a cross-section passing through the pocket center C and including the axis O of the bearing (hereinafter referred to as the radial cross-section) is Ry, and the diameter is 2Ry (hereinafter referred to as the radial pocket diameter 2Ry). Note that the pocket center C and the center of the ball 5 coincide in design. The center of the arc of the radial inner peripheral surface D is the symbol C’ in Fig. 3 and is eccentric toward the radial inner peripheral surface D side from the pocket center C. In Fig. 3, the radial inner peripheral surface D shows that it continues from the outer diameter side end d2 to the inner diameter side end d1 at the bottom F of the pocket 11. Fig. 3 shows a cross-section passing through the bearing center line, but this radial pocket diameter 2Ry is set not only in this cross-section but also in any cross-section including the radial straight line connecting the pocket center C and the axis O of the bearing (however, when a recess H such as an oil reservoir is provided on the inner surface of the pocket 11, the location of the recess H is excluded).

[0043] Further, as shown in FIG. 4, the inner surface of the pocket 11 is an inner surface (spherical surface) that describes an arc along the circumferential direction of the bearing, and the radius in the circumferential direction of the bearing is set to Rz. That is, in a cross-section (hereinafter referred to as the circumferential cross-section) that is orthogonal to the bearing radial straight line passing through the pocket center C at the pocket center C, the radius of the inner circumferential surface E of the pocket 11 (hereinafter referred to as the circumferential inner circumferential surface E) is Rz, and the diameter is 2Rz (hereinafter referred to as the circumferential pocket diameter 2Rz). In FIG. 4, the circumferential inner circumferential surface E extends from the tip G of the retaining claw 14 through the bottom F of the pocket 11 to the tip G of the retaining claw 14 on the opposite side. FIG. 4 shows a cross-section that passes through the pocket center C and is orthogonal to the bearing radial straight line connecting the pocket center C and the axis O of the bearing. This circumferential pocket diameter 2Rz is set not only in this cross-section but also in any cross-section that passes through the pocket center C and intersects the bearing radial straight line passing through the pocket center C (however, when a concave portion H such as an oil reservoir is provided on the inner surface of the pocket 11, the location of the concave portion H is excluded).

[0044] In addition, in FIGS. 3 and 4, the differences in the diameters (radii) of the respective arcs and the positional relationships of the centers of the arcs are exaggeratedly drawn.

[0045] Here, the dimensional relationship between the diameter φx of the ball 5, the radial pocket diameter 2Ry on the inner surface of the pocket 11, and the circumferential pocket diameter 2Rz is φx < 2Ry < 2Rz is set to be.

[0046] Regarding this point, unless the radial pocket diameter 2Ry (see FIG. 3) and the circumferential pocket diameter 2Rz (see FIG. 4) of the pocket 11 are larger than the diameter φx of the ball 5, the pocket 11 will firmly hold the ball 5, so that the cage 10 cannot be formed. For this reason, the requirements of φx < 2Ry and φx < 2Rz are required.

[0047] Furthermore, by setting the circumferential pocket diameter 2Rz (see FIG. 4) larger than the radial pocket diameter 2Ry (see FIG. 3) of the pocket 11, interference between the cage 10 and surrounding members (such as the inner ring 3 and outer ring 4, etc.) caused by the retardation of the ball 5 during high-speed rotation can be avoided. That is, while the ball 5 rotates in the circumferential direction of the bearing, due to the speed difference in the circumferential direction, the ball 5 is pulled by the cage 10, making it easier to avoid the interference associated with the deformation occurring in the cage 10. This is the effect achieved by ensuring that the second clearance w2 (see FIG. 4) between the ball 5 and the circumferential inner peripheral surface E of the pocket 11 is larger than the first clearance w1 (see FIG. 3) between the ball 5 and the radial inner peripheral surface D of the pocket 11 by setting 2Ry < 2Rz.

[0048] In the cross-section of FIG. 3, the radial inner peripheral surface D represents an arc with a diameter of 2Ry, reference sign d1 indicates the inner diameter side end d1 thereof, and reference sign d2 indicates the outer diameter side end d2 thereof. Further, in the cross-section of FIG. 4, the circumferential inner peripheral surface E represents an arc with a diameter of 2Rz, and reference sign F indicates the bottom F thereof. Also, reference sign G indicates the tip G of the retaining claw 14.

[0049] On the other hand, if 2Ry of the pocket 11 is too large, the radial play between the ball 5 and the cage 10 will increase, and interference between the cage 10 and surrounding members (such as the inner ring 3 and outer ring 4, etc.) is likely to occur. Also, during high-speed rotation, combined with the influence of centrifugal force deformation, the above interference is more likely to occur. Therefore, it is not preferable to make 2Ry too large. Thus, the inventors of the present application have confirmed that the requirement of 2Ry < 2Rz is desirable. However, as a condition for suppressing such interference, it is a requirement that the cage 10 uses engineering plastic as its material.

[0050] Also, as shown in FIG. 4, the circumferential inner peripheral surface E includes a first inner peripheral surface E on the base 12 side 1 and a second inner peripheral surface E on the tip side of the column portion 13 with respect to the retaining claw 14 side, that is, the first inner peripheral surface E 1 The center C 2 of the arc of the second inner peripheral surface E 2 is the center C 2 of the arc of the first inner peripheral surface E 1 and the center C 1It is eccentric toward the base 12 side rather than this. Thereby, while maintaining the holding function of the ball 5, it becomes possible to secure a large second gap w2 between the ball 5 and the circumferential-direction inner peripheral surface E of the pocket 11.

[0051] In FIG. 4, the first inner peripheral surface E on the circumferential-direction inner peripheral surface E 1 center C of the arc 1 and the second inner peripheral surface E 2 center C of the arc 2 the line connecting them is parallel to the axial direction of the bearing. Also, the pocket center C is the center C of the arc of the first inner peripheral surface E 1 center C of the arc 1 and the second inner peripheral surface E 2 center C of the arc 2 is desirably the midpoint between them. Further, the center C of the arc of the first inner peripheral surface E 1 center C of the arc 1 and the second inner peripheral surface E 2 center C of the arc 2 The distance w between them is appropriately set according to the diameter φx of the ball 5, the specifications of the bearing, etc. For example, it can be set to a value between 0.1 and 0.2 mm.

[0052] In addition, as a demerit due to excessively increasing the circumferential-direction pocket diameter 2Rz, there is a point that the axial play of the cage 10 increases. When the axial play of the cage 10 increases, there is a concern about interference with the seal member 20 depending on the usage conditions. From such a situation, it is desirable to secure a clearance of 0.1 mm or more in the axial direction between the seal member 20 and the cage 10 in consideration of the above axial play and the deformation of the cage 10 due to centrifugal force.

[0053] According to the above configuration, dmn={(D + d) / 2}×n D: Bearing outer diameter (mm) d: Bearing inner diameter (mm) n: Rotational speed (min -1 ) Under high-speed conditions where the dmn value defined by is 700,000 or more at its maximum rotational speed, the bearing 1 can be applied. At the same time, the intrusion of foreign matter of a size that affects the bearing life can also be suppressed. Furthermore, the deformation of the cage 10 during high-speed operation can be suppressed, and it is possible to prevent foreign matter from getting caught between the cage 10 and the seal member 20.

[0054] Regarding the radius Rz of the circumferential inner peripheral surface E described above, the first inner peripheral surface E 1 of the radius Rz 1 and the second inner peripheral surface E 2 of the radius Rz 2 are preferably set to the same numerical value. However, as long as there is no problem with the holding function of the ball 5 and the securing of the second gap w2, for example, as shown in FIG. 5, the first inner peripheral surface E 1 of the radius Rz 1 and the second inner peripheral surface E 2 of the radius Rz 2 may be different numerical values. At this time, the radius Rz of the first inner peripheral surface E 1 may be set to a value larger than the radius Rz of the second inner peripheral surface E 1 2 2 of the radius Rz 2 or the radius Rz of the first inner peripheral surface E 1 of the radius Rz 1 may be set to a value smaller than the radius Rz of the second inner peripheral surface E 2 of the radius Rz 2 2

[0055] In FIG. 5, the installation of the recess H for the oil reservoir formed on the inner surface of the pocket 11 is omitted. Here, the theoretical connection point between the first inner peripheral surface E 1 and the second inner peripheral surface E 2 is on the plane passing through the pocket center C and perpendicular to the axial direction of the bearing. This theoretical intersection point is indicated by the reference numeral J in FIG. 5. When the theoretical intersection point J is viewed macroscopically, if the first inner peripheral surface E 1 and the second inner peripheral surface E 2 are directly connected, a break point will intervene between the two. Therefore, in the vicinity of the theoretical intersection point J, it is preferably attached smoothly so that the curvature is as continuous as possible so that no break points or the like where the curvature is discontinuous intervene. At this time, for example, as shown in FIG. 4, the first inner peripheral surface E1 and the second inner peripheral surface E 2 If a concave portion H is provided as an oil reservoir between them, the theoretical intersection point J is located within the concave portion H, and the problem of the bending point between the first inner peripheral surface E 1 and the second inner peripheral surface E 2 can be solved.

[0056] In the above embodiment, since the lubricant (lubricating oil) is supplied to the bearing internal space A from both the axial one end side and the axial other end side, the content of the present invention has been described by taking the configuration of a double-sided seal provided with the seal member 20 at the openings at both axial ends as an example. As another example, for instance, when the supply of the lubricant (lubricating oil) to the bearing internal space A is in one direction from the axial one end side to the axial other end side, a configuration of a single-sided seal provided with the seal member 20 only at the opening at the axial one end side may be adopted. That is, in the case of a single-sided seal, it is desirable that the seal member 20 is set at the opening on the side where the lubricant (lubricating oil) is supplied. Further, in the case of a single-sided seal, it is desirable that the cage 10 is inserted into the bearing internal space A from the non-seal side where the seal member 20 is not provided.

[0057] As described above, for the bearing 1 used under high-speed conditions where the dmn value at the maximum rotational speed is 700,000 or more, by applying a crowned cage using engineering plastic, it is required to suppress the deformation of the cage 10 due to high-speed rotation. However, when applying this resin-made crowned cage, for example, when the inflow amount of the lubricant (lubricating oil) into the bearing internal space A is large, there is a concern that the bearing life may be reduced. Also, depending on the usage conditions of the bearing 1, there is a concern that the bearing life may be reduced due to foreign matters such as gear wear debris entering the bearing internal space A. For this reason, in the present invention, by adopting a seal member 20 capable of maintaining the contact portion of the seal lip 21 in a fluid lubrication state, it is possible to suppress the intrusion of foreign matters that affect the bearing life and to control the inflow amount of the lubricant (lubricating oil). That is, the synergistic effect of a resin-made crowned cage having a predetermined shape and performance and a seal member 20 capable of maintaining the contact portion of the seal lip 21 in a fluid lubrication state realizes an extension of the bearing life compared to the conventional case.

[0058] Table 1 below shows the results of the rapid acceleration and deceleration tests based on the differences in the internal oil amounts in the resin crown retainers.

[0059] [Table 1]

[0060] From the above results, it can be seen that the shorter the amount of lubricant (lubricating oil) flowing into the bearing internal space A, the longer the bearing life. This is presumably because the smaller the amount of lubricant (lubricating oil) flowing in, the smaller the stirring resistance. As described above, for the seal member 20 capable of maintaining the contact portion of the seal lip 21 in a fluid lubrication state, for example, it is possible to prevent the intrusion of foreign matter of 0.050 mm or more that affects fluid lubrication and the bearing life. Further, although the seal member 20 is a contact seal, since it is in a fluid lubrication state during operation, it is not necessary to ensure an excessive amount of lubricant (lubricating oil) inflow. As in Test Nos. 3 and 4 in Table 1 above, it can be seen that there is no problem even if the excessive entry of lubricant (lubricating oil) into the bearing internal space A is avoided.

[0061] In the above embodiment, the retainer 10 is made of engineering plastic, but the material of the retainer 10 only needs to contain at least engineering plastic.

[0062] In the above embodiment, as an example of the rotating shaft, the rotating shaft of a drive motor provided in an electric transportation device such as an electric vehicle, or the rotating shaft of a speed reducer or a speed increaser provided in those electric transportation devices is cited. However, in addition to that, the bearing 1 of the present invention and the bearing device using the bearing 1 can also be applied to the support portions of rotating shafts in various transportation devices, industrial machines, etc. For example, it can also be applied to the shafts of power transmission paths, constant velocity joints, propeller shafts, superchargers, transmissions, rotating portions of wheel bearings in various transportation devices, or the support portions of rotating shafts of various machine tools, generators, etc.

[0063] In the above-described embodiment, the seal lip 21 of the seal member 20 is disposed on the inner ring 3 side as the sealed ball bearing 1, and the configuration of the present invention has been described. However, this may be reversed inside and outside. For example, as shown in FIG. 8, a configuration in which the seal lip 21 is disposed on the outer ring 4 side may be adopted.

[0064] In the above-described embodiment, the elastic portion 24 of the seal member 20 is rubber, and the rubber is vulcanized and adhered to the core metal 23. However, the rubber may be integrated with the core metal 23 by an adhesion method other than vulcanization adhesion. Further, if the strength and durability of the seal member 20 are ensured, a seal member 20 composed only of the elastic portion 24 without using the core metal 23 may be adopted. Furthermore, as the material of the elastic portion 24, for example, a synthetic resin may be used in addition to rubber.

[0065] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the scope of claims, and all modifications within the meaning and scope equivalent to the scope of claims are intended to be included.

Explanation of Signs

[0066] 1 Bearing (sealed ball bearing) 3 Inner ring 4 Outer ring 5 Ball (rolling element) 10 Cage 11 Pocket 12 Base 13 Column 20 Seal member 21 Seal lip 27 Projection 28 Gap A Bearing internal space B Seal sliding surface C Pocket center D Radial inner peripheral surface E Circumferential inner peripheral surface E 1 First inner peripheral surface E 2 Second inner peripheral surface

Claims

1. An internal ring (3), an external ring (4), balls (5) disposed between the internal ring (3) and the external ring (4), a cage (10) having pockets (11) for holding the balls (5) along the circumferential direction, and a seal member (20) for closing an opening at an axial end of a bearing internal space (A) formed between the internal ring (3) and the external ring (4). dmn={(D+d) / 2}×n D: Bearing outer diameter (mm) d: Bearing inner diameter (mm) n: Rotation speed (min －１ ) In a ball bearing used in an environment where the dmn value defined by the following formula is 700,000 or more: The seal member (20) is fixed to one of the internal ring (3) and the external ring (4) and has a seal lip (21) that slidably contacts a seal sliding surface (B) provided on the other. The seal lip (21) has a plurality of protrusions (27) arranged in the circumferential direction. The plurality of protrusions (27) create a gap (28) between adjacent protrusions (27) in the circumferential direction, and the seal lip (21) and the seal sliding surface (B) are in a fluid lubrication state by an oil film of lubricating oil drawn from the gap (28) between the protrusions (27) and the seal sliding surface (B) as the bearing rotates. The seal lip (21) is formed in such a manner that it is possible to achieve this state. The cage (10) includes an annular base (12) and a plurality of column portions (13) protruding in one direction from the base (12), and is a crown-shaped cage containing engineering plastic. In a cross-section passing through the center (C) of the pocket (11) of the ball (5) and including the axis (O) of the bearing, the radius Ry of the radially inner peripheral surface (D) of the pocket (11), and in a cross-section perpendicular to the bearing radial line passing through the pocket center (C) at the pocket center (C), the radius Rz of the circumferentially inner peripheral surface (E) of the pocket (11) satisfy the dimensional relationship φx < 2Ry < 2Rz. The circumferential inner peripheral surface (E) includes a first inner peripheral surface (E １ ) on the base (12) side and a second inner peripheral surface (E １ ) on the tip side of the column portion (13) with respect to the first inner peripheral surface (E ２ ). The center (C ２ ) of the second inner peripheral surface (E ２ ) is eccentric toward the base (12) side with respect to the center (C １ ) of the first inner peripheral surface (E １ ). The center (C') of the radial inner peripheral surface (D) is set at a point with a radius Ry from the bottom (F) of the pocket (11), which is the intersection of the circumferential inner peripheral surface (E) and the radial inner peripheral surface (D), toward the pocket center (C). A sealed ball bearing.

2. The radius Rz of the circumferential-direction inner peripheral surface (E) is the radius Rz of the first inner peripheral surface (E １ ), and the radius Rz of the second inner peripheral surface (E １ ), and the radius Rz of the second inner peripheral surface (E ２ ), and the radius Rz of the second inner peripheral surface (E ２ ), and the radius Rz of the second inner peripheral surface (E The sealed ball bearing according to claim 1, wherein they are set equal.

3. The first inner peripheral surface (E １ ), and between the second inner peripheral surface (E ２ ), a concave portion (H) is provided as an oil reservoir. The sealed ball bearing according to claim 1.

4. The sealed ball bearing according to claim 1, wherein the seal lip (21) is made of a single or a plurality of materials selected from nitrile rubber, acrylic rubber, and fluororubber.

5. The sealed ball bearing according to claim 1, wherein when the supply of the lubricant to the bearing internal space is in one direction from one axial end side to the other axial end side, the seal member (20) is provided only at the opening at one axial end side.

6. A bearing device that uses the sealed ball bearing according to any one of claims 1 to 5 to support a rotating shaft provided in a drive motor, a speed reducer, or a speed increaser for an electric transport device with the sealed ball bearing.

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