Angular ball bearing

Abstract

To provide an angular ball bearing capable of maintaining the good state of lubricating a rolling contact part with an inner ring raceway on a ball rolling surface.SOLUTION: Out of a plurality of pillar parts 23a constituting a cage 5a, the axial front end surface of an outside pillar piece 26a located radially outside of a cutout 25a, and the axial front end surface of a back face protrusion 30a, provided for a seal device 6a and protruded to the annular space 20 side in the axial direction, are opposed to each other in the axial direction. A diameter Φ1 of a virtual circle passing through a radial inside face 27a at the axial front end of the outside pillar piece 26a is the same as an inner diameter Φ2 of the axial front end of the back face protrusion 30a or smaller than the inner diameter Φ2, and larger than an outer diameter Φ3 of a groove shoulder part 48a of an inner ring raceway 10a. A difference between the diameter Φ1 and the inner diameter Φ2 is smaller than a difference between the diameter Φ1 and the outer diameter Φ3.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to angular contact ball bearings. [Background technology]

[0002] In angular contact ball bearings used in automotive hub unit bearings, as described in JP 2014-77508 A, for example, a cage for angular contact ball bearings is used to arrange multiple balls at equal intervals in the circumferential direction and hold each ball so that it can roll freely. The cage for angular contact ball bearings includes an annular rim portion, multiple pillar portions extending axially from multiple circumferential positions on the rim portion, and multiple pockets for holding the balls, each surrounded on three sides by two circumferentially adjacent pillar portions and the rim portion.

[0003] For rolling bearings such as angular contact ball bearings, the load rating required for selecting a bearing is calculated using the following formula (1), which expresses the basic dynamic load rating Cr. Cr=b m f c (icоsα) 0.7 Z 2 / 3 Dw 1.8 ···(1) Here, in equation (1), b m and f c is a constant determined by the material, shape, and manufacturing quality of the bearing, i is the number of rows of rolling elements in one bearing, α is the contact angle, Z is the number of rolling elements in one row, and Dw is the diameter of the rolling element.

[0004] According to the above formula (1), by increasing the number of balls (Z) in one row, it is possible to improve the basic dynamic load rating Cr of the angular contact ball bearing, thereby extending the bearing life.

[0005] Japanese Patent Application Laid-Open No. 2019-173966 discloses a cage structure for an angular contact ball bearing that allows the number of balls in one row to be increased. Figure 8 shows a hub unit bearing 101 equipped with a cage 100 of a conventional structure described in Japanese Patent Application Laid-Open No. 2019-173966.

[0006] Hub unit bearing 101 rotatably supports hub 103, which rotates together with the wheel, on the radially inner side of outer ring 102, which is fixed to a vehicle body member, via multiple balls 104. Balls 104 are positioned between outer ring raceway 102a provided on the inner peripheral surface of outer ring 102 and inner ring raceway 103a arranged on the outer peripheral surface of hub 103, while being held by cage 100, so as to be able to roll freely.

[0007] The cage 100 comprises an annular rim portion 105, a plurality of pillar portions 106 extending axially from a plurality of circumferential positions on the rim portion 105, and a plurality of pockets 107 surrounded on three sides by two circumferentially adjacent pillar portions 106 and the rim portion 105. Each of the balls 104 is held in each pocket 107 so that it can roll freely.

[0008] The inner diameter of the pocket 107 is slightly larger than the outer diameter (ball diameter) of the ball 104. The center of the pocket 107 substantially coincides with the center of the ball 104 held in the pocket 107.

[0009] The cage 100 has notches 108 that connect two circumferentially adjacent pockets 107 in the range from the axial tip of the column portion 106 (the end on the right side in FIG. 8) to the axial middle portion. This makes it possible to reduce the distance between circumferentially adjacent balls 104 compared to a structure without notches in the column portion. This makes it possible to increase the number of balls 104 that can be retained by the cage 100, thereby improving the basic dynamic load rating Cr of the angular contact ball bearing. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-77508 [Patent Document 2] Japanese Patent Application Publication No. 2019-173966 Summary of the Invention [Problem to be solved by the invention]

[0011] In the hub unit bearing 101 of the conventional structure described in JP 2019-173966 A, there is a possibility that the grease that lubricates the rolling contact portion between the rolling surfaces of the balls 104 and the inner ring raceway 103a may be insufficient.

[0012] In hub unit bearing 101, grease is sealed in annular space 109 in which balls 104 are arranged. In inner ring rotating hub unit bearing 101, the grease sealed in annular space 109 tends to move radially outward due to the action of centrifugal force associated with the rotation of hub 103 and / or the revolution of balls 104, and tends to accumulate in outer ring raceway 102a. Some of the grease that accumulates in outer ring raceway 102a adheres to the rolling surfaces of balls 104 as balls 104 rotate and revolve, and is returned to inner ring raceway 103a.

[0013] However, because the opening edge of pocket 107 is a ridge made up of an indivisible corner, some of the grease adhering to the rolling surfaces of balls 104 in outer ring raceway 102a is scraped off by the opening edge of pocket 107 as balls 104 rotate. Therefore, the amount of grease returning to inner ring raceway 103a tends to decrease.

[0014] In particular, in the hub unit bearing 101 described in JP 2019-173966 A, the cage 100 has notches 108 in the pillar portions 106, and the opening edges of the notches 108 that open into the circumferential side surfaces of the pillar portions 106 are ridges consisting of non-differentiable corners. Therefore, grease adhering to the rolling surfaces of the balls 104 in the outer ring raceway 102a is also scraped off by the opening edges of the notches 108 that open into the circumferential side surfaces of the pillar portions 106 as the balls 104 rotate. Specifically, as each ball 104 rotates, grease adhering to the rolling surface of each ball 104 in outer ring raceway 102a is mainly scraped off by the edge closer to the ball 104 (the front edge in the direction of revolution of ball 104) of the radially outer surface (the surface facing radially inward) of notch 108 provided in column portion 106 located on the rear side of the orbital direction of ball 104. As a result, the amount of grease returning to inner ring raceway 103a is more likely to be reduced.

[0015] As described above, in hub unit bearing 101 with a conventional structure, there is a possibility that there will be a shortage of grease lubricating the rolling contact area between the rolling surfaces of balls 104 and inner ring raceway 103a. This can lead to abnormal noise due to wear on the rolling surfaces of balls 104 and inner ring raceway 103a. Furthermore, there is a possibility that the rotational resistance (dynamic torque) will increase and the rolling fatigue life will be shortened.

[0016] An object of the present disclosure is to provide an angular contact ball bearing that can maintain a good lubrication state at the rolling contact portion between the rolling surfaces of the balls and the inner ring raceway. [Means for solving the problem]

[0017] An angular contact ball bearing according to one aspect of the present disclosure includes a stationary ring, a rotating ring, a plurality of balls, a cage, and a sealing device.

[0018] The stationary ring has an angular outer ring raceway on its inner circumferential surface. The rotating ring has an angular inner ring raceway on its outer circumferential surface. The plurality of balls are disposed between the outer ring raceway and the inner ring raceway. The cage holds the plurality of balls so that they can roll freely. The sealing device closes the opening of an annular space that exists between the inner peripheral surface of the stationary ring and the outer peripheral surface of the rotating ring.

[0019] The seal device has a stationary side seal member fixed to the stationary ring. The stationary seal member has an annular shape and a back surface projection that projects axially toward the annular space.

[0020] The cage has an annular rim portion, a plurality of pillar portions extending axially from multiple circumferential positions on the rim portion, and a plurality of pockets for holding the balls, surrounded on three sides by two circumferentially adjacent pillar portions and the rim portion.

[0021] The column portion is formed in a range from the axial tip (the end closest to the sealing device) including the portion passing through the pitch circle of the ball to the axial middle portion, and has a notch that connects two circumferentially adjacent pockets, and an outer column piece located radially outward of the notch.

[0022] The axial tip surface of the outer post piece and the axial tip surface of the rear projection face each other in the axial direction. The diameter Φ1 of an imaginary circle passing through the radially inner surface of the axial tip of the outer post piece is the same as or smaller than the inner diameter Φ2 of the axial tip of the back projection, and is larger than the outer diameter Φ3 of the groove shoulder of the inner ring raceway. The difference between the diameter Φ1 and the inner diameter Φ2 is smaller than the difference between the diameter Φ1 and the outer diameter Φ3.

[0023] In an angular ball bearing according to one aspect of the present disclosure, the outer column piece has an inclined surface on the radially inner surface of at least a portion including the axial tip, which is inclined in a direction that inclines radially outward as it approaches the axial tip. In a cross section cut along an imaginary plane including the central axis of the rim portion, an extension of the inclined surface intersects with the inner peripheral surface of the rear projection.

[0024] In an angular ball bearing according to one embodiment of the present disclosure, one sealing device is provided at each opening on both axial sides of the annular space, and one retainer is provided near each sealing device. The two sets of cages and seal devices arranged near each other have the axial tip surfaces of the outer post pieces and the axial tip surfaces of the back projections opposed to each other in the axial direction, the diameter Φ1 of an imaginary circle passing through the radially inner surfaces of the axial tip portions of the outer post pieces is the same as or smaller than the inner diameter Φ2 of the axial tip portions of the back projections, and is larger than the outer diameter Φ3 of the groove shoulder portion of the inner ring raceway, and the difference between the diameter Φ1 and the inner diameter Φ2 is smaller than the difference between the diameter Φ1 and the outer diameter Φ3. [Effects of the Invention]

[0025] According to an angular contact ball bearing according to one aspect of the present disclosure, it is possible to maintain a good lubrication state at the rolling contact portion between the rolling surface of the ball and the inner ring raceway. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a cross-sectional view showing a hub unit bearing, which is an angular contact ball bearing, according to a first example of an embodiment of the present disclosure. [Figure 2] FIG. 2 is an enlarged view of a portion corresponding to the X portion in FIG. [Figure 3] FIG. 3 is an enlarged view of a portion corresponding to the Y portion in FIG. [Figure 4] FIG. 4 is a partially enlarged perspective view showing the cage with the balls held in the pockets. [Figure 5] FIG. 5 is a partially enlarged perspective view of the cage. [Figure 6] FIG. 6 is a diagram corresponding to FIG. 2 and showing a second example of an embodiment of the present disclosure. [Figure 7] FIG. 7 is a diagram corresponding to FIG. 3, but for the second example. [Figure 8] FIG. 8 is a partial cross-sectional view showing a hub unit bearing of a conventional structure. DETAILED DESCRIPTION OF THE INVENTION

[0027] [Example 1] A first example of an embodiment of the present disclosure will be described with reference to FIGS.

[0028] In this example, an angular contact ball bearing according to one aspect of the present disclosure is applied to a hub unit bearing for rotatably supporting an automobile wheel relative to a suspension device.

[0029] The angular contact ball bearing according to one aspect of the present disclosure is not limited to hub unit bearings, but can also be applied to single-row or double-row angular contact ball bearings incorporated into various mechanical devices.

[0030] Below, we will explain the overall structure of the hub unit bearing 1, and then explain the specific structures of the retainers 5a, 5b and sealing devices 6a, 6b, and the relationship between the retainers 5a, 5b, sealing devices 6a, 6b, and the outer diameters of the groove shoulder portions 48a, 48b of the inner ring raceways 10a, 10b.

[0031] [Overall structure of hub unit bearing] Hub unit bearing 1 includes outer ring 2 which is a stationary ring, hub 3 which is a rotating ring, multiple balls 4a, 4b, two cages 5a, 5b, and two sealing devices 6a, 6b. Hub unit bearing 1 is an inner ring rotating type hub unit bearing.

[0032] The hub unit bearing 1 of this example is a so-called third-generation hub unit bearing for a driving wheel. However, an angular ball bearing according to one aspect of the present disclosure can also be applied to hub unit bearings for a driven wheel, as well as first- and second-generation hub unit bearings.

[0033] In the following description, unless otherwise specified, the axial direction, radial direction, and circumferential direction of the hub unit bearing 1 refer to the axial direction, radial direction, and circumferential direction of the outer ring 2. The axial direction, radial direction, and circumferential direction of the outer ring 2 coincide with the axial direction, radial direction, and circumferential direction of the hub 3. Additionally, the outer axial direction refers to the outer side in the width direction of the vehicle when the hub unit bearing 1 is assembled to the vehicle, and the inner axial direction refers to the center side in the width direction of the vehicle when the hub unit bearing 1 is assembled to the vehicle.

[0034] The outer ring 2 is made of a hard metal such as medium carbon steel. The outer ring 2 has a generally cylindrical shape and has double-row angular outer ring raceways 7a, 7b on its inner circumferential surface. The outer ring 2 has a stationary flange 8 that protrudes radially outward at an axially intermediate portion. The stationary flange 8 has support holes 9 that penetrate the axial direction at multiple circumferential locations at the radially intermediate portion.

[0035] In this example, the support holes 9 are configured as threaded holes. The outer ring 2 is supported and fixed to the suspension by threading a support bolt, which is inserted through a through hole provided in the knuckle of the suspension, into the support hole 9 of the stationary flange 8 from the inside in the axial direction, so that the outer ring 2 does not rotate even when the wheel rotates.

[0036] The hub 3 is disposed coaxially with the outer ring 2, radially inward of the outer ring 2. The hub 3 has angular double-row inner ring raceways 10a, 10b on its outer peripheral surface. The hub 3 has a groove shoulder 48a on a portion of its outer peripheral surface adjacent to the axially outer side of the axially outer inner ring raceway 10a, and a groove shoulder 48b on a portion of its outer peripheral surface adjacent to the axially inner side of the axially inner inner ring raceway 10b. The groove shoulders 48a, 48b have cylindrical outer peripheral surfaces. The hub 3 has a rotation flange 11 that protrudes radially outward at a portion that protrudes axially outward beyond the outer ring 2. The hub 3 has a cylindrical pilot portion 12 at its axially outer end. Furthermore, the hub 3 has a spline hole 13 that axially penetrates the hub 3 in its radial center.

[0037] The rotating flange 11 has mounting holes 14 that penetrate the axial direction at multiple locations circumferentially in the radially middle portion. Studs 15 for connecting and fixing a braking rotor such as a disc or drum and a wheel that constitutes a wheel to the rotating flange 11 are press-fitted into each mounting hole 14 with serrations. That is, in this example, the mounting holes 14 are cylindrical holes.

[0038] A braking rotating body such as a brake disc and a wheel of a vehicle are connected and fixed to the rotating flange 11 by inserting a pilot portion 12 into a central hole provided in the center of each and inserting studs 15 into through holes provided at multiple locations circumferentially in the radially middle portion of each, and then screwing a hub nut onto the tip of the stud 15.

[0039] The mounting holes of the rotating flange can also be threaded holes. In this case, the braking rotor and wheel are connected and fixed to the rotating flange by threading a hub bolt, which passes through a through hole provided in the braking rotor and a through hole provided in the wheel, into the mounting hole from the outside in the axial direction.

[0040] The tip of a drive shaft that is rotated and driven by an engine or electric motor as a drive source is spline-engaged with the spline hole 13. When the vehicle is running, the hub 3 is rotated by the drive shaft, which rotates and drives the wheels and braking rotors that are coupled and fixed to the rotating flange 11 of the hub 3.

[0041] The hub 3 is configured by combining an inner ring 16 and a hub ring 17 .

[0042] The inner ring 16 is made of a hard metal such as bearing steel and has an annular shape. The inner ring 16 has an inner ring raceway 10b and a groove shoulder 48b on the axially inner side on its outer circumferential surface.

[0043] The hub ring 17 is made of a hard metal such as medium carbon steel and includes an inner ring raceway 10a and a groove shoulder 48a on the axially outer side, a rotation flange 11, a pilot portion 12, and a spline hole 13.

[0044] The hub ring 17 has a small diameter step 18, which has a smaller outer diameter than the adjacent axially outer portion, at a portion located axially more inward than the axially outer inner ring raceway 10a. The hub ring 17 has a step surface 19, facing axially inward, at the axially outer end of the small diameter step 18.

[0045] The inner ring 16 is fitted onto the small diameter step 18 of the hub ring 17 with an interference fit, and its axially outer end face abuts against a step surface 19 of the hub ring 17. In this way, the hub ring 17 and the inner ring 16 are joined and fixed together.

[0046] The hub wheel and inner wheel can also be joined and fixed by clamping the inner wheel from both axial sides between the stepped surface of the hub wheel and a crimping portion provided on the axially inner end of the hub wheel, or by clamping the inner wheel from both axial sides between the stepped surface of the hub wheel and a nut threaded onto the axially inner end of the hub wheel.

[0047] The balls 4a, 4b are made of hard metal such as bearing steel or ceramics. The balls 4a, 4b are arranged in rows between double-row outer ring raceways 7a, 7b and double-row inner ring raceways 10a, 10b, with multiple balls per row. The double-row balls 4a, 4b are given a back-to-back (DB) contact angle.

[0048] The hub unit bearing 1 of this example has a so-called differential PCD type structure in which the pitch diameter of the balls 4a in the axially outer row is larger than the pitch diameter of the balls 4b in the axially inner row. However, an angular contact ball bearing according to one aspect of the present disclosure can also be applied to a differential PCD type structure in which the pitch diameter of the balls in the axially outer row is smaller than the pitch diameter of the balls in the axially inner row, and to an equal PCD type hub unit bearing in which the pitch diameter of the balls in the axially outer row is equal to the pitch diameter of the balls 4b in the axially inner row.

[0049] The cages 5a and 5b have an annular shape and hold a plurality of balls 4a and 4b so that they can roll freely. In this example, one cage 5a and one cage 5b are provided near the sealing devices 6a and 6b so as to face rim portions 22a and 22b (described later).

[0050] The axially outer cage 5a rollably holds the axially outer row of balls 4a, and the axially inner cage 5b rollably holds the axially inner row of balls 4b. The multiple balls 4a, 4b held by the cages 5a, 5b are arranged at equal intervals in the circumferential direction.

[0051] The sealing devices 6a and 6b close the opening of the annular space 20 that exists between the inner peripheral surface of the outer ring 2 and the outer peripheral surface of the hub 3. In this example, the sealing devices 6a and 6b are provided one at each of the openings on both axial sides of the annular space 20.

[0052] The axially outer sealing device 6a closes the axially outer end opening of the annular space 20 and is disposed axially outward of the balls 4a and cage 5a. The axially inner sealing device 6b closes the axially inner end opening of the annular space 20 and is disposed axially inward of the balls 4b and cage 5b. The sealing devices 6a and 6b prevent leakage of grease 21 (see FIG. 1) sealed in the annular space 20 and prevent foreign matter such as muddy water from entering the annular space 20. In FIG. 1, the grease 21 is shown with a matte pattern.

[0053] The grease 21 sealed in the annular space 20 lubricates the rolling contact portions between the rolling surfaces of the balls 4a, 4b and the outer ring raceways 7a, 7b and the inner ring raceways 10a, 10b.

[0054] [Specific structure of the cage] The cages 5a and 5b have the following specific structure.

[0055] The two retainers 5a, 5b assembled into the hub unit bearing 1 of this example are separate retainers with different diameters of the rim portions 22a, 22b, but have the same basic configuration. Therefore, in the description of the retainers 5a, 5b, the common configuration will be described only for the axially outer retainer 5a, and the different configuration will be described for each retainer 5a, 5b. Because the two retainers 5a, 5b are assembled in opposite directions in the axial direction, the description of the axial direction will be reversed for the two retainers 5a, 5b. In the following description, the axial tip side of the bar portions 23a, 23b of the retainers 5a, 5b, i.e., the axial outside of the axially outer retainer 5a and the axial inside of the axially inner retainer 5b, will be referred to as the "one axial side." The axial base side of the bar portions 23a, 23b, i.e., the axial inside of the axially outer retainer 5a and the axial outside of the axially inner retainer 5b, will be referred to as the "other axial side."

[0056] The cage 5a (5b) is a so-called crown-type cage for an angular contact ball bearing, which is integrally formed as a whole by injection molding (axial draw molding) of synthetic resin.

[0057] The synthetic resin that constitutes the cage 5a (5b) may be various synthetic resins such as polyamide 66 (PA66), polyamide 6 (PA6), polyamide 46 (PA46), polyamide 9T (PA9T), polyphenylene sulfide (PPS), polyethylene terephthalate (PET), polyacetal (POM), phenolic resin (PF), etc. These synthetic resins may be mixed with various reinforcing fibers such as glass fiber, carbon fiber, and aramid fiber, as needed.

[0058] The cage 5a (5b) includes a rim portion 22a (22b), a plurality of pillar portions 23a (23b), and a plurality of pockets 24a (24b).

[0059] The rim portion 22a (22b) is formed in an annular shape.

[0060] The inner and outer peripheral surfaces of the rim portion 22a (22b) are cylindrical. The rim portion 22a constituting the axially outer retainer 5a has an outer diameter smaller than the portion adjacent to the axially inner side of the axially outer outer ring raceway 7a, and an inner diameter larger than the portion adjacent to the axially inner side of the axially outer inner ring raceway 10a. The rim portion 22b constituting the axially inner retainer 5b has an outer diameter smaller than the portion adjacent to the axially outer side of the axially inner outer ring raceway 7b, and an inner diameter larger than the portion adjacent to the axially outer side of the axially inner inner ring raceway 10b.

[0061] The axial base ends (ends on the other axial side) of the multiple pillar portions 23a (23b) are connected to the side surface of the rim portion 22a (22b) on one axial side facing the balls 4a (4b). Of the side surface on one axial side of the rim portion 22a (22b), the part that deviates from the pillar portions 23a (23b in the circumferential direction is configured as a partially spherical concave surface. The side surface on the other axial side of the rim portion 22a (22b) is configured as a flat surface that is perpendicular to the central axis of the rim portion 22a (22b).

[0062] The multiple pillar portions 23a (23b) extend from multiple locations in the circumferential direction of the rim portion 22a (22b) toward one axial side. That is, the multiple pillar portions 23a constituting the axially outer retainer 5a extend axially outward, and the multiple pillar portions 23b constituting the axially inner retainer 5b extend axially inward. The multiple pillar portions 23a (23b) are arranged at equal intervals in the circumferential direction.

[0063] The radial width of the column portion 23a (23b) increases toward the tip end at the base end portion of the column portion 23a (23b), and remains almost unchanged along the axial direction at the tip end portion of the column portion 23a (23b).

[0064] The side surfaces on both sides in the circumferential direction of the column portion 23a (23b) are configured as partially spherical concave surfaces.

[0065] The pocket 24a (24b) is a portion that holds the ball 4a (4b) so that it can roll freely, and is surrounded on three sides by two circumferentially adjacent pillar portions 23a (23b) and the rim portion 22a (22b). The inner surface of the pocket 24a (24b) is formed by the circumferential side surfaces of the two circumferentially opposing pillar portions 23a (23b) and a portion of the side surface on one axial side of the rim portion 22a (22b) that is circumferentially offset from the pillar portions 23a (23b). The inner surface of the pocket 24a (24b) is formed in a partially spherical shape, with a radius of curvature slightly larger than the radius of curvature of the rolling surface of the ball 4a (4b).

[0066] The circumferential side surfaces of the pillar portions 23a (23b) are curved so as to protrude inward into the pockets 24a (24b) from the radial middle toward both radial ends, and the opening width of the pockets 24a, 24b, which corresponds to the distance between the circumferential side surfaces of two circumferentially adjacent pillar portions 23a (23b), is smaller than the diameter of the balls 4a (4b) at the radially outer and inner ends of the pillar portions 23a (23b). This prevents the balls 4a (4b) from slipping out radially outward or radially inward from the inside of the pockets 24a (24b).

[0067] The center of the pocket 24a (24b) substantially coincides with the center of the ball 4a (4b) held in the pocket 24a (24b).

[0068] In this example, the column portion 23a (23b) has a notch 25a (25b) that connects two circumferentially adjacent pockets 24a (24b) in a range from the axial tip (end on one axial side) including the part that passes through the pitch circle of the ball 4a (4b) to the axial middle portion.

[0069] The notch 25a (25b) opens on the axial tip end surface (one axial end surface) and both circumferential side surfaces of the column portion 23a (23b). The notch 25a (25b) is cut out in a substantially U-shape when viewed circumferentially, from the axial tip end to the axial middle portion of the column portion 23a (23b).

[0070] The pillar portion 23a (23b) has an outer pillar piece 26a (26b) located radially outward of the notch 25a (25b).

[0071] The outer column piece 26a (26b) has an inclined surface 43a (43b) on the radially inner side surface 27a (27b) including at least the axial tip end, the inclined surface 43a (43b) inclining radially outward as it approaches the axial tip end. In this example, the inclined surface 43a (43b) is provided on the radially inner side surface 27a (27b) in the range from the axial middle portion of the outer column piece 26a (26b) to the axial tip end.

[0072] The pillar portion 23a (23b) has an inner pillar piece 28a (28b) located radially inward of the notch 25a (25b).

[0073] The inner column piece 28a (28b) has an inclined surface 44a (44b) on its radially inner surface ranging from the axial middle portion to the axial tip portion (end portion on one axial side), which is inclined radially outward as it approaches the axial tip side. This prevents the tip side portion (end portion on one axial side) of the inner column piece 28a (28b) from coming into contact with the inner ring raceway 10a (10b) even if the inner column piece 28a (28b) is extended axially further than the outer column piece 26a (26b) to make it easier to cut out from the cages 5a (5b) stacked on the positioning device.

[0074] [Specific structure of the sealing device] The sealing devices 6a and 6b have the following specific structures.

[0075] The axially outer sealing device 6 a is attached to the axially outer end of the outer ring 2 and closes the axially outer opening of the annular space 20 .

[0076] The axially outer sealing device 6a is composed solely of a stationary side sealing member 29a fixed to the outer ring 2, which is a stationary ring.

[0077] The stationary side seal member 29a has an annular shape and has a back surface projection 30a that projects axially toward the annular space 20. That is, the stationary side seal member 29a has a back surface projection 30a that projects axially inward.

[0078] The axially inner tip of the rear projection 30a is disposed near the plurality of balls 4a.

[0079] In this example, the stationary side seal member 29a is a seal ring, and includes a core metal 31a and a seal material 32a.

[0080] The core metal 31a is made of a metal plate such as a cold-rolled steel plate, and is configured in an annular shape as a whole.

[0081] The core metal 31a has a cylindrical fitting tube portion 33a, a circular ring-shaped outward flange portion 34 that is bent radially outward from the axially outer end of the fitting tube portion 33a, and an inward flange portion 35a whose radially outer end is connected to the axially inner end of the fitting tube portion 33a and has a crank-shaped cross-sectional shape.

[0082] The inward flange portion 35a has an outer circular ring portion 45 having a generally hollow circular plate shape, an inner circular ring portion 46 having a generally hollow circular plate shape and positioned axially outward from the outer circular ring portion 45, and a cylindrical connecting tube portion 47 connecting the outer circular ring portion 45 and the inner circular ring portion 46.

[0083] In this example, the rear projection 30a is formed by a part of the core metal 31a. Specifically, the rear projection 30a is formed by the axially inner part of the fitting cylindrical portion 33a, and the outer circular ring portion 45 and connecting cylindrical portion 47 of the inward flange portion 35a. The rear projection 30a has a horizontal U-shaped cross section.

[0084] The core metal 31a is supported and fixed to the outer ring 2 by tightly fitting the fitting cylindrical portion 33a into the axially outer end portion of the outer ring 2. The axially inner surface of the outward flange portion 34 abuts against the axially outer end face of the outer ring 2.

[0085] The seal member 32a is made of an elastic material such as an elastomer containing rubber, and is configured in an annular shape as a whole. The seal member 32a is bonded and fixed to the core metal 31a, and covers the surface of the core metal 31a.

[0086] The seal member 32a has one or more seal lips. In this example, the seal member 32a has multiple (three in the illustrated example) seal lips 36a to 36c on its radially inner side. The tips of the seal lips 36a to 36c come into sliding contact with the outer peripheral surface of the hub 3 or the axially inner surface of the rotating flange 11 over the entire circumference.

[0087] The sealing material 32a has a dam portion 37 and an eaves lip 38 on its radially outer side. The dam portion 37 has an outer diameter larger than the outer peripheral surface of the axially outer end of the outer ring 2, and by covering the radially outer end of the outward flange portion 34 of the core metal 31a, it prevents foreign matter such as muddy water that runs along the outer peripheral surface of the outer ring 2 from reaching the seal lip 36a. The eaves lip 38 extends axially outward from the dam portion 37, with its tip positioned closely opposite the axially inner surface of the rotating flange 11, forming a labyrinth seal.

[0088] The axially inner sealing device 6 b is attached to the axially inner end of the outer ring 2 and closes the axially inner opening of the annular space 20 .

[0089] The axially inner seal device 6b is composed of a stationary-side seal member 29b fixed to the outer ring 2, which is a stationary ring, and a rotating-side seal member 39 fixed to the hub 3, which is a rotating ring. In other words, the seal device 6b is composed of a combined seal ring.

[0090] The stationary side seal member 29b has an annular shape and has a back surface projection 30b that projects axially toward the annular space 20. That is, the stationary side seal member 29b has a back surface projection 30b that projects axially outward.

[0091] The axially outer tip of the rear projection 30b is disposed near the plurality of balls 4b.

[0092] In this example, the stationary side seal member 29b is a seal ring, and includes a core metal 31b and a seal material 32b.

[0093] The core metal 31b is made of a metal plate such as a cold-rolled steel plate, and is configured in an annular shape as a whole.

[0094] The core metal 31b has a cylindrical fitting tube portion 33b and an inward flange portion 35b whose radially outer end is connected to the axially outer end of the fitting tube portion 33b and has a crank-shaped cross section.

[0095] The core metal 31b is supported and fixed to the outer ring 2 by fitting the fitting cylindrical portion 33b into the axially inner end of the outer ring 2 by interference fit.

[0096] The seal member 32b is made of an elastic material such as an elastomer containing rubber, and is configured in an annular shape as a whole. The seal member 32b is bonded and fixed to the core metal 31b, and covers the surface of the core metal 31b.

[0097] The seal member 32b has one or more seal lips. In this example, the seal member 32b has multiple (two in the illustrated example) seal lips 36d, 36e on its radially inner side. The tips of the seal lips 36d, 36e are in sliding contact with the surface of the rotating-side seal member 39 over the entire circumference.

[0098] The sealing material 32b has, at its radially intermediate portion, a back lip 40. The back lip 40 has a cylindrical shape and protrudes axially outward from a radially intermediate portion of the axially outer surface of the inward flange portion 35b of the core metal 31b.

[0099] In this example, the rear projection 30b is formed by a part of the sealing material 32b. Specifically, the rear projection 30b is formed by the rear lip 40.

[0100] In this example, the rotating-side seal member 39 is a slinger made of a rust-resistant metal plate such as stainless steel, has a substantially L-shaped cross section, and is configured as a ring as a whole. The rotating-side seal member 39 has a cylindrical fixed cylinder portion 41 and a circular plate portion 42 that is bent radially outward from the axially inner end of the fixed cylinder portion 41.

[0101] The rotating-side seal member 39 is supported and fixed to the hub 3 by fitting the fixed cylindrical portion 41 tightly onto the inner ring 16 that constitutes the hub 3. The tip of the seal lip 36e of the stationary-side seal member 29b is in sliding contact with the outer peripheral surface of the fixed cylindrical portion 41, and the tip of the seal lip 36d of the stationary-side seal member 29b is in sliding contact with the axially outer surface of the annular plate portion 42.

[0102] When implementing an angular contact ball bearing according to one aspect of the present disclosure, the structure of the seal device is not limited to the structure of the present example described above, as long as the stationary seal member fixed to the stationary ring is provided with a back projection. The back projection may be provided on a portion of the metal core, a portion of the elastic seal member, or on another member constituting the stationary seal member. Furthermore, the shape (cross-sectional shape), axial projection, radial width, etc. of the back projection may be modified as appropriate.

[0103] [Relationship between the cage, seal device and outer diameter of the groove shoulder of the inner ring raceway] The axially outer cage 5a and the sealing device 6a have the following first, second and third relationships.

[0104] First, the axial tip surface (axially outer end surface) of the outer column piece 26a constituting the cage 5a and the axial tip surface (axially inner end surface) of the back projection 30a constituting the sealing device 6a face each other in the axial direction. In other words, the axial tip surface of the outer column piece 26a and the axial tip surface of the back projection 30a are arranged overlapping each other in the axial direction. In this example, the radially outer portion of the axial tip surface of the outer column piece 26a and the radially inner portion of the axial tip surface of the back projection 30a face each other in the axial direction.

[0105] In this example, the axial tip surface of the outer column piece 26a and the axial tip surface of the back projection 30a face each other in the axial direction via a gap of about 1 / 10 to 1 / 5 the diameter D1 of the ball 4a.

[0106] Secondly, the diameter Φ1 of an imaginary circle passing through the radially inner surface 27a of the axial tip end portion of the outer column pieces 26a constituting the cage 5a is OUT However, the inner diameter Φ2 of the axial tip of the rear projection 30a that constitutes the sealing device 6a OUT Same as or inner diameter Φ2 OUT and the outer diameter (groove shoulder diameter) Φ3 of the groove shoulder portion 48a of the inner ring raceway 10a is OUT Larger than (Φ3 OUT <Φ1 OUT ≦Φ2 OUT In this example, the outer diameter of the groove shoulder 48a of the inner ring raceway 10a is Φ3 OUT corresponds to the sliding contact diameter of the seal lip 36c.

[0107] In this example, the diameter Φ OUT However, the inner diameter Φ2 OUT The size is 90% or more and less than 100%, preferably 95% or more and 99% or less of the above.

[0108] Third, the diameter Φ1 OUT and the inner diameter Φ2 OUT The difference between (|Φ1 OUT -Φ2 OUT |) is the diameter Φ1 OUT and the outer diameter Φ3 OUT The difference between (|Φ1 OUT -Φ3 OUT |) is smaller than (|Φ1 OUT -Φ2 OUT |<|Φ1 OUT -Φ3 OUT |).

[0109] In this example, the axially inner cage 5b and seal device 6b also have the following first, second and third relationships.

[0110] First, the axial tip surface (axially inner end surface) of the outer post piece 26b constituting the cage 5b and the axial tip surface (axially outer end surface) of the back projection 30b constituting the sealing device 6b face each other in the axial direction. In other words, the axial tip surface of the outer post piece 26b and the axial tip surface of the back projection 30b are arranged to overlap each other in the axial direction.

[0111] In this example, the axial tip surface of the outer column piece 26b and the axial tip surface of the back projection 30b face each other in the axial direction via a gap of about 1 / 10 to 1 / 5 the diameter D2 of the ball 4b.

[0112] Secondly, the diameter Φ1 of an imaginary circle passing through the radially inner surface 27b of the axial tip end portion of the outer column pieces 26b constituting the cage 5b IN is the inner diameter Φ2 of the axial tip of the back projection 30b that constitutes the sealing device 6b IN Same as or inner diameter Φ2 IN and the outer diameter (groove shoulder diameter) Φ3 of the groove shoulder portion 48b of the inner ring raceway 10b is IN Larger than (Φ3 IN <Φ1 IN ≦Φ2 IN In this example, the outer diameter Φ3 of the groove shoulder 48b of the inner ring raceway 10b is IN corresponds to the inner diameter of the rotating seal member 39, more specifically, the fitting diameter of the rotating seal member 39 and the inner ring 16.

[0113] In this example, the diameter Φ IN However, the inner diameter Φ2 IN The size is 90% or more and less than 100%, preferably 95% or more and 99% or less of the above.

[0114] Third, the diameter Φ1 IN and the inner diameter Φ2 IN The difference between (|Φ1 IN -Φ2 IN |) is the diameter Φ1 IN and the outer diameter Φ3 IN The difference between (|Φ1 IN -Φ3 IN |) is smaller than (|Φ1 IN -Φ2 IN |<|Φ1IN -Φ3 IN |).

[0115] When implementing an angular ball bearing according to one embodiment of the present disclosure, if there are multiple combinations of retainers and sealing devices, it is sufficient that at least one set of retainer and sealing device has the first, second, and third relationships described above.

[0116] The cages 5a, 5b incorporated into the hub unit bearing 1 of this example are provided with notches 25a, 25b that connect two circumferentially adjacent pockets 24a, 24b in the column sections 23a, 23b, from the axial tip to the axial middle, including the portion through which the pitch circles of the balls 4a, 4b pass. As a result, compared to a structure without notches in the column sections, the distance between circumferentially adjacent balls 4a, 4b is shorter, and the total number of balls 4a, 4b increases. As a result, the basic dynamic load rating of the hub unit bearing 1 is higher.

[0117] In particular, according to the hub unit bearing 1 of this embodiment, it is possible to maintain a good lubricated state at the rolling contact portions between the rolling surfaces of the balls 4a, 4b and the inner ring raceways 10a, 10b.

[0118] That is, in this example, with respect to the axially outer retainer 5a and the seal device 6a, the axial tip end surface of the outer column piece 26a and the axial tip end surface of the back projection 30a are opposed to each other in the axial direction. Also, the diameter Φ1 of an imaginary circle passing through the radially inner side surface 27a of the axial tip end portions of the outer column pieces 26a is OUT The inner diameter Φ2 of the axial tip of the rear projection 30a OUT Same as or inner diameter Φ2 OUT and the outer diameter Φ3 of the groove shoulder 48a of the inner ring raceway 10a is OUT Larger than (Φ3 OUT <Φ1 OUT ≦Φ2 OUT ). Furthermore, the diameter Φ1 OUT and the inner diameter Φ2 OUT The difference between the diameter Φ1 OUT and the outer diameter Φ3 OUT is smaller than the difference between

[0119] Therefore, as each ball 4a rotates, the grease 21 scraped off by the edge (the front edge in the direction of revolution of the ball 4a) of the radially outer surface (the radially inner surface 27a of the outer column piece 26a) of the notch 25a provided in the column portion 23a located on the rear side of the ball 4a in the direction of revolution moves from the radially inner surface 27a of the outer column piece 26a to the inner circumferential surface of the back projection 30a (connecting cylindrical portion 47), and then moves radially inward along the axially inner surface of the sealing device 6a (inner circular ring portion 46) and returns to the inner ring raceway 10a. Therefore, the amount of grease 21 returning to the inner ring raceway 10a increases. As a result, the rolling contact area between the rolling surfaces of the balls 4a and the inner ring raceway 10a is maintained in a good lubrication state.

[0120] In this example, the axial tip end surface of the outer column piece 26b and the axial tip end surface of the back projection 30b of the axial inner retainer 5b and the seal device 6b are also opposed to each other in the axial direction. IN The inner diameter Φ2 of the axial tip of the rear projection 30a IN Same as or inner diameter Φ2 IN and the outer diameter Φ3 of the groove shoulder 48b of the inner ring raceway 10b is IN Larger than (Φ3 IN <Φ1 IN ≦Φ2 IN ). Furthermore, the diameter Φ1 IN and the inner diameter Φ2 IN The difference between the diameter Φ1 IN and the outer diameter Φ3 IN is smaller than the difference between

[0121] Therefore, as each ball 4b rotates, the grease 21 is scraped off by the edge of the radially outer surface (the radially inner surface 27b of the outer column piece 26b) of the notch 25b in the column portion 23b located on the rear side of the ball 4b in the orbital direction, which is closer to the ball 4b (the front edge in the orbital direction of the ball 4b). The grease 21 then moves from the radially inner surface 27b of the outer column piece 26b to the inner circumferential surface of the back projection 30b, and further moves radially inward along the axially outer surface of the radially inner portion of the sealing device 6b, returning to the inner ring raceway 10b. Therefore, the amount of grease 21 returning to the inner ring raceway 10b increases. As a result, the lubrication state of the rolling contact area between the rolling surfaces of the balls 4b and the inner ring raceway 10b is maintained favorably.

[0122] As a result, wear on the rolling surfaces of the balls 4a, 4b and the inner ring raceways 10a, 10b is reduced, preventing the generation of abnormal noise. Furthermore, the rotational resistance (dynamic torque) of the hub unit bearing 1 is suppressed, extending the rolling fatigue life.

[0123] In this example, the radially inner side surfaces 27a, 27b of the outer column pieces 26a, 26b, including at least the axial tip portions (one axial side portions), have inclined surfaces 43a, 43b that are inclined radially outward toward the axial tip portions, so that the grease 21 scraped off by the opening edges of the notches 25a, 25b moves efficiently along the inclined surfaces 43a, 43b to the inner circumferential surfaces of the back projections 30a, 30b by centrifugal force, thereby effectively increasing the amount of grease 21 that flows back to the inner ring raceways 10a, 10b.

[0124] [Example 2] A second example of the embodiment of the present disclosure will be described with reference to FIGS.

[0125] In this example, the outer column pieces 26a, 26b constituting the cages 5a, 5b have inclined surfaces 43a, 43b on the radially inner side surfaces 27a, 27b of the portions including at least the axial tip portions (one axial side portion), which are inclined in a direction radially outward as they approach the axial tip portions. In the illustrated example, the outer column pieces 26a, 26b have inclined surfaces 43a, 43b on the radially inner side surfaces 27a, 27b in the range from the axial middle portions to the axial tip portions.

[0126] In this example, the axially outer retainer 5a and the seal device 6a have the following fourth relationship in addition to the above-described first, second, and third relationships.

[0127] That is, as a fourth relationship, as shown in FIG. 6, in a cross section cut along an imaginary plane including the center axis of the rim portion 22a, an extension line La of the inclined surface 43a intersects with the inner peripheral surface of the rear projection 30a.

[0128] In this example, the axially inner cage 5b and seal device 6b also have the following fourth relationship in addition to the above-described first, second, and third relationships.

[0129] That is, as a fourth relationship, as shown in FIG. 7, in a cross section cut along an imaginary plane including the center axis of the rim portion 22b, an extension line Lb of the inclined surface 43b intersects with the inner peripheral surface of the back projection 30b.

[0130] In the present embodiment described above, the extension lines La and Lb of the inclined surfaces 43a and 43b intersect with the inner peripheral surfaces of the back projections 30a and 30b, so that the grease 21 (see FIG. 1) moves efficiently from the inclined surfaces 43a and 43b to the inner peripheral surfaces of the back projections 30a and 30b due to the action of centrifugal force, thereby effectively increasing the amount of grease 21 that flows back to the inner ring raceways 10a and 10b.

[0131] In the illustrated example, the inner peripheral surfaces of the rear projections 30a, 30b are flat surfaces extending in the axial direction, but they may be inclined surfaces having a linear generatrix such that the base end portion (root portion) is positioned radially inward relative to the tip end portion.Furthermore, the inner peripheral surfaces of the rear projections 30a, 30b may be concave curved surfaces having an arc-shaped generatrix.

[0132] Other configurations and effects of the second example are the same as those of the first example. [Explanation of symbols]

[0133] 1 Hub unit bearing 2 outer ring 3. Hub 4a, 4b balls 5a, 5b retainer 6a, 6b Sealing device 7a, 7b Outer raceway 8 Stationary Flange 9 Support hole 10a, 10b Inner raceway 11 Rotating flange 12 Pilot Division 13 Spline hole 14 Mounting holes 15 studs 16 Inner Circle 17 Hub wheel 18 Small diameter stepped section 19 Step surface 20 Annular Space 21 Grease 22a, 22b rim section 23a, 23b pillar part 24a, 24b pockets 25a, 25b notch 26a, 26b outer column piece 27a, 27b radially inner surface 28a, 28b inner column piece 29a, 29b Stationary side seal member 30a, 30b Rear protrusion 31a, 31b core metal 32a, 32b sealing material 33a, 33b Fitting cylinder part 34 Outward flange 35a, 35b Inward flange 36a~36e Seal lip 37 Weir 38 Eaves lip 39 Rotating side seal member 40 rear lip 41 Fixed cylinder part 42 Annular plate part 43a, 43b Slope 44a, 44b Slope 45 Outer ring part 46 Inner ring 47 Connecting tube 48a, 48b groove shoulder 100 retainer 101 Hub unit bearing 102 outer ring 102a outer raceway 103 Hub 103a Inner raceway 104 balls 105 Rim 106 Column section 107 Pocket 108 Notch 109 Annular Space

Claims

1. a stationary ring having an angular outer ring raceway on its inner circumferential surface; a rotating ring having an angular inner ring raceway on its outer circumferential surface; a plurality of balls disposed between the outer ring raceway and the inner ring raceway; a cage for holding the plurality of balls so that they can roll freely; a sealing device that closes an opening of an annular space that exists between an inner peripheral surface of the stationary ring and an outer peripheral surface of the rotating ring, the seal device has a stationary-side seal member fixed to the stationary ring, the stationary side seal member has an annular shape and a back surface projection that projects axially toward the annular space, the cage has an annular rim portion, a plurality of pillar portions extending in the axial direction from a plurality of circumferential positions of the rim portion, and a plurality of pockets for holding the balls, the pockets being surrounded on three sides by two circumferentially adjacent pillar portions and the rim portion, the column portion is formed in a range from an axial tip portion to an axial middle portion, including a portion passing through the pitch circle of the ball, and has a notch that connects two of the pockets adjacent in the circumferential direction, and an outer column piece located radially outward of the notch, The axial tip surface of the outer post piece and the axial tip surface of the rear projection face each other in the axial direction, a diameter Φ1 of an imaginary circle passing through the radially inner surface of the axial tip end portions of the plurality of outer column pieces is equal to or smaller than an inner diameter Φ2 of the axial tip end portion of the back projection, and is larger than an outer diameter Φ3 of a groove shoulder portion of the inner ring raceway, The difference between the diameter Φ1 and the inner diameter Φ2 is smaller than the difference between the diameter Φ1 and the outer diameter Φ3. Angular contact ball bearing.

2. The outer column piece has, on a radially inner surface of at least a portion including an axial tip portion, an inclined surface that is inclined in a direction toward the radially outer side as it approaches the axial tip side, In a cross section cut along an imaginary plane including a central axis of the rim portion, an extension line of the inclined surface intersects with an inner peripheral surface of the rear projection.

2. The angular contact ball bearing according to claim 1.

3. The sealing device is provided at each of the openings on both axial sides of the annular space, The retainers are provided one by one near the seal devices, Two sets of the retainer and the seal device arranged adjacent to each other, The axial tip surface of the outer post piece and the axial tip surface of the rear projection face each other in the axial direction, a diameter Φ1 of an imaginary circle passing through the radially inner surface of the axial tip end portions of the plurality of outer column pieces is equal to or smaller than an inner diameter Φ2 of the axial tip end portion of the back projection, and is larger than an outer diameter Φ3 of a groove shoulder portion of the inner ring raceway, The difference between the diameter Φ1 and the inner diameter Φ2 is smaller than the difference between the diameter Φ1 and the outer diameter Φ3.

2. The angular contact ball bearing according to claim 1.

Images