Inner ring separable angular contact ball bearing

Abstract

To provide an inner ring separate-type angular ball bearing which hardly causes a scratch on a surface of a ball and inner / outer ring raceway grooves by smoothly inserting an inner ring into an outer ring.SOLUTION: A point between a ball 3 and an outer ring shoulder part 6 when the ball 3 of an outer ring assembly falls to the inside of a radial direction by its own weight is set as a contact point X, and a point at which a center line passing a center O of the ball 3 intersects with a surface of the ball 3 is set as a cross point Y. A rotation angle β around the center O of the ball 3 in a direction into which the ball 3 falls rather than the cross point Y is set as a positive angle, and a rotation angle in a reverse direction is set as a negative angle. An abutment point Z at which the ball 3 and an inner ring counterbore part 9 firstly abut on each other when inserting an inner ring 2 downward is located at a positive side rather than the cross point Y. A relationship of 1.00<C / D≤2.50 is established between a magnitude C of a ball circumscription-side clearance being a clearance between a circumscription circle diameter Ro of the ball 3 and a groove bottom of an outer ring raceway groove 5, and a magnitude D of a ball inscription-side superimposition being a difference between an inscription circle diameter Ri of the ball 3 when inserting the inner ring 2 downward from the inner ring counterbore part 9 side, and an outside diameter Rc of the inner ring counterbore part 9.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an inner ring separable angular ball bearing configured to smoothly insert an inner ring when inserting the inner ring into a structure that integrally holds an outer ring, a cage, and rolling elements.

Background Art

[0002] Conventionally, bearings used in automotive automatic transmissions are subject to high radial loads as well as axial loads, and thus many tapered roller bearings have been used. However, in recent years, due to the need for fuel efficiency improvement in automobiles, the use of angular ball bearings as transmission bearings has been increasing. Angular ball bearings can bear both radial and axial loads and have lower torque than tapered roller bearings.

[0003] When an angular ball bearing is used in a transmission, a separable angular ball bearing is generally adopted to ensure the workability of assembling and disassembling the transmission. A separable angular ball bearing is an angular ball bearing configured such that balls do not fall out of the pockets of the cage even when the inner ring or the outer ring is separated.

[0004] As a separable angular ball bearing, for example, the inner ring separable angular ball bearing of Patent Document 1 below is known. The inner ring separable angular ball bearing of Patent Document 1 includes an outer ring, an inner ring coaxially disposed radially inside the outer ring, a plurality of balls incorporated with a circumferential interval between the outer ring and the inner ring, and a cage that holds the plurality of balls.

[0005] The inner circumference of the outer ring is provided with an outer ring raceway groove on which the balls roll and make contact, an outer ring counterbore portion adjacent to one side of the outer ring raceway groove in the axial direction, and an outer ring shoulder portion adjacent to the other side of the outer ring raceway groove in the axial direction. Similarly, the outer circumference of the inner ring is provided with an inner ring raceway groove on which the balls roll and make contact, an inner ring counterbore portion adjacent to one side of the inner ring raceway groove in the axial direction, and an inner ring shoulder portion adjacent to the other side of the inner ring raceway groove in the axial direction. The outer ring counterbore portion is a part of the outer ring raceway groove that has been partially or completely removed, and the inner ring counterbore portion is a part of the inner ring raceway groove that has been partially or completely removed. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2008-95929 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In the inner ring separation type angular contact ball bearing described in Patent Document 1, for example, as shown in Figure 13, when inserting the inner ring 54 into the retainer (hereinafter referred to as the outer ring assembly) which integrally holds the outer ring 51, cage 52, and balls 53 fitted into the housing hole 50, the balls 53 that have fallen radially inward due to their own weight are further pulled downward by the inner ring 54 which is inserted downward, causing the outer ring 51, balls 53, and cage 52 to separate, or the balls 53 to become jammed between the outer ring 51 and the inner ring 54 as the inner ring 54 is inserted, making it impossible to insert the inner ring 54 smoothly, and there is a risk that the surface of the balls 53 or the inner and outer ring raceway grooves will be damaged.

[0008] The problem that this invention aims to solve is to provide an inner ring separation type angular contact ball bearing in which the inner ring is smoothly inserted into the outer ring assembly, making it less likely for scratches to occur on the surface of the balls or the inner and outer ring raceway grooves. be. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides an inner ring separable angular ball bearing having the following configuration. an outer ring, an inner ring coaxially disposed radially inside the outer ring, a plurality of balls incorporated at intervals in the circumferential direction between the outer ring and the inner ring, a cage for holding the plurality of balls, On the inner circumference of the outer ring, there are provided an outer ring raceway groove with which the balls rollingly contact, an outer ring shoulder adjacent to one axial side of the outer ring raceway groove, and an outer ring counterbore portion adjacent to the other axial side of the outer ring raceway groove and having an inner diameter larger than that of the outer ring shoulder. On the outer circumference of the inner ring, there are provided an inner ring raceway groove with which the balls rollingly contact, an inner ring counterbore portion adjacent to one axial side of the inner ring raceway groove, and an inner ring shoulder adjacent to the other axial side of the inner ring raceway groove and having an outer diameter larger than that of the inner ring counterbore portion. In the inner ring separable angular ball bearing in which when the inner ring is separated, the balls are supported so as not to drop radially inward from the pockets formed in the cage, With the outer ring, the cage, and the balls held integrally, when the ball drops radially inward due to its own weight, the contact point between the ball and the outer ring shoulder and the center line passing through the center of the ball intersect the surface of the ball at an intersection point. When the rotation angle around the center of the ball in the direction in which the ball drops is positive and the rotation angle in the reverse direction from the intersection point is negative, when the inner ring is inserted downward from the inner ring counterbore portion side, the contact point where the ball and the inner ring counterbore portion first come into contact is on the positive side of the intersection point. There is a relationship of 1.00 < C / D ≤ 2.50 between the size C of the ball outer circumscribed side clearance, which is the radial clearance between the outer diameter of the circumscribed circle of the ball when the ball drops radially inward due to its own weight and the bottom of the outer ring raceway groove, and the size D of the ball inner circumscribed side overlap, which is the difference between the inner diameter of the inscribed circle of the ball when the inner ring is inserted downward from the inner ring counterbore portion side and the outer diameter of the inner ring counterbore portion. The inner ring separable angular ball bearing is characterized by this.

[0010] In this way, by positioning the contact point on the positive side of the intersection, when inserting the inner ring downwards into the outer ring assembly, the ball is not pulled downwards by the inner ring counterbore portion of the inner ring, thus allowing for smooth assembly.

[0011] Furthermore, by setting the relative size of the ball outer clearance C and the ball inner overlap D within the above range, the ball is pushed back along the outer ring raceway groove as the inner ring is inserted, allowing for smooth insertion. If the ball inner overlap D is larger than the ball outer clearance C, a tight fit will occur between the ball and the inner ring during insertion, putting pressure on the ball and potentially causing scratches or cracks. Also, if the value obtained by dividing the ball outer clearance C by the ball inner overlap D is greater than 2.50, the gap between the ball and the inner and outer ring raceway grooves will become larger, potentially resulting in a different contact angle than expected or the ball riding up onto the shoulder of the inner and outer rings. For this reason, it is necessary to set the relative size of the ball outer clearance C and the ball inner overlap D within the above range.

[0012] Preferably, a tapered surface is formed on the outer diameter surface side of the inner ring counterbore portion, where the axial inclination angle α satisfies 0° < α ≤ 30°, and the outer diameter gradually decreases as it moves away from the inner ring raceway groove.

[0013] This method reduces the contact pressure on the ball compared to when it directly contacts the chamfered portion of the inner ring counterbore, thus making it less likely for scratches to occur on the ball's surface. Furthermore, by forming a tapered surface, the length of the flat portion of the counter that requires grinding (see Lc in Figure 4) is reduced. Because it becomes shorter, the cycle time during manufacturing can be reduced. However, if this inclination angle α is greater than 30 degrees, it becomes difficult to secure the length of the flat section of the inner ring width required for machining (see Lw in Figure 4), so it is preferable to keep it within the above range.

[0014] It is preferable that a solid lubricating film is formed on the outer diameter surface side of the inner ring counterbore portion.

[0015] By doing so, since the friction between the ball and the outer diameter surface of the inner ring counter bore portion is reduced, the inner ring can be smoothly inserted without damaging the surface of the ball.

[0016] The above inner ring separable angular ball bearing is particularly suitable for use as a bearing for an automobile transmission.

Advantages of the Invention

[0017] In the inner ring separable angular ball bearing of this invention, in a state where the balls of the outer ring assembly have fallen, the contact point between the ball and the inner ring counter bore portion is made positive with respect to the intersection defined on the surface of the ball, and a relationship of 1.00 < C / D ≦ 2.50 is established between the size C of the clearance on the outer circumscribed side of the ball and the size D of the overlap on the inner circumscribed side of the ball. As a result, when the inner ring is inserted downward into the outer ring assembly, the balls are not pulled downward by the inner ring counter bore portion of this inner ring, so that the insertion can be performed smoothly. Moreover, by setting the magnitude relationship between the size C of the clearance on the outer circumscribed side of the ball and the size D of the overlap on the inner circumscribed side of the ball within the above range, the balls are not bitten between the outer ring and the inner ring as the inner ring is inserted, and the surface of the balls and the inner and outer ring raceway grooves are not easily damaged.

Brief Description of the Drawings

[0018] [Figure 1] Cross-sectional view showing an embodiment of the inner ring separable angular ball bearing according to this invention [Figure 2] Cross-sectional view showing the main part of FIG. 1 [Figure 3] Diagram showing the dimensional relationship of each member in FIG. 2 [Figure 4] Cross-sectional view of the inner ring of the inner ring separable angular ball bearing shown in FIG. 1 [Figure 5] Cross-sectional view showing a state where one outer ring assembly of the inner ring separable angular ball bearing shown in FIG. 1 is attached to a housing hole [Figure 6] Cross-sectional view showing a state where one more outer ring assembly is attached to the housing hole following FIG. 5 [Figure 7]Following Figure 6, this is a cross-sectional view showing the state in which a shaft body with one inner ring has been inserted. [Figure 8] Following Figure 7, this is a cross-sectional view showing the state with one more inner ring inserted. [Figure 9] Cross-sectional view showing the contact force acting on the ball when the inner ring is inserted. [Figure 10] Figure 1 shows a cross-sectional view of a modified example of an inner ring-separated angular contact ball bearing, illustrating the main parts. [Figure 11] Figure 1 shows a cross-sectional view illustrating a first example of the use of an inner ring-separated angular contact ball bearing in an automobile transmission. [Figure 12] Figure 1 shows a cross-sectional view illustrating a second example of the use of an inner ring-separated angular contact ball bearing in an automobile transmission. [Figure 13] Cross-sectional view of a key part showing the inner ring insertion process in a conventional inner ring separation type angular contact ball bearing. [Modes for carrying out the invention]

[0019] Hereinafter, an embodiment of the inner ring-separated angular contact ball bearing A according to the present invention will be described with reference to the drawings. The inner ring-separated angular contact ball bearing A shown in Figure 1 has an outer ring 1, an inner ring 2 arranged coaxially on the radially inner side of the outer ring 1, a plurality of balls 3 (steel balls) incorporated between the outer ring 1 and the inner ring 2 at circumferential intervals, and a cage 4 that holds the plurality of balls 3.

[0020] The inner circumference of the outer ring 1 has an outer ring raceway groove 5 into which the ball 3 rolls and makes contact, an outer ring shoulder 6 adjacent to one side of the outer ring raceway groove 5 in the axial direction (left side in Figure 1), and the other side of the outer ring raceway groove 5 in the axial direction (in Figure 1) An outer ring counterbore portion 7 is provided adjacent to the outer ring (on the right side). The outer ring raceway groove 5 is a groove with a circular arc cross-section that extends circumferentially along the inner circumference of the outer ring 1. The outer ring 1 is made of bearing steel. The outer ring counterbore portion 7 is a portion of the outer ring raceway groove 5 with part or all of the groove shoulder removed. The inner diameter of the outer ring counterbore portion 7 is larger than the inner diameter of the outer ring shoulder portion 6.

[0021] The outer circumference of the inner ring 2 is provided with an inner ring raceway groove 8 on which the balls 3 roll and make contact, an inner ring counterbore portion 9 adjacent to one side of the inner ring raceway groove 8 in the axial direction (left side in Figure 1), and an inner ring shoulder portion 10 adjacent to the other side of the inner ring raceway groove 8 in the axial direction. The inner ring raceway groove 8 is a groove with a circular arc cross-section that extends circumferentially around the outer circumference of the inner ring 2. The inner ring 2 is made of bearing steel. The inner ring counterbore portion 9 is a portion of the inner ring raceway groove 8 with part or all of the groove shoulder removed. The outer diameter of the inner ring shoulder portion 10 is larger than the outer diameter of the inner ring counterbore portion 9.

[0022] As shown in Figures 3 and 4, the outer circumferential surface of the inner ring counterbore 9 is a tapered surface 11 in which the outer diameter gradually decreases as it moves away from the inner ring raceway groove 8. The axial inclination angle α of this tapered surface 11 is set to be greater than 0 degrees and less than or equal to 30 degrees. An axially flat counter flat portion (range Lc in Figure 4) is formed between the inner ring raceway groove 8 and the tapered surface 11. In addition, a flat width flat portion (range Lw in Figure 4) is formed on the axial end face of the inner ring counterbore 9.

[0023] A solid lubricating film is formed on the outer circumferential surface of the inner ring counterbore portion 9. This solid lubricating film reduces friction with the ball 3 when the inner ring 2 is inserted, preventing damage to the surface of the ball 3 during insertion. In particular, if the solid lubricating film is formed on the tapered surface 11, the insertion of the inner ring 2 can be made even smoother. Blackening or diamond-like carbon (DLC) can be used as this solid lubricating film. Blackening is a porous black oxide film that provides lubrication by retaining lubricating oil in its pores. DLC is a low-friction film with properties intermediate between diamond and graphite, and it also provides lubrication. In addition, molybdenum-based or fluorine-based solid lubricating films can also be used. Note that this solid lubricating film is not an essential component and may be omitted in some cases.

[0024] The retainer 4 has a counter-side annular portion 12 extending circumferentially on one axial side (left side in Figure 1) relative to the ball 3, an anti-counter-side annular portion 13 extending circumferentially on the other axial side (right side in Figure 1) relative to the ball 3, and a plurality of columnar portions 14 that connect the counter-side annular portion 12 and the anti-counter-side annular portion 13 by passing between adjacent balls 3 in the circumferential direction. The counter-side annular portion 12, the anti-counter-side annular portion 13, and the columnar portions 14 define a pocket 15 that accommodates the ball 3. When the inner ring 2 is separated, the ball 3 is supported by the pocket 15 so that it does not fall out radially inward. The counter-side annular portion 12 and the anti-counter-side annular portion 13 position the retainer 4 by fitting onto the ball 3. At this time, neither the counter-side annular portion 12 nor the anti-counter-side annular portion 13 is in contact with the outer ring 1 and the inner ring 2.

[0025] Resin is used as the material for the retainer 4. This resin can be a polyamide such as PA46 (polyamide 46), PA66 (polyamide 66), PA9T (polynonameethylene terephthalamide), polyether ether ketone (PEEK), or polyphenylene sulfide (PPS).

[0026] As shown in Figure 2, in the retainer (hereinafter referred to as the outer ring assembly) which integrally holds the outer ring 1, the retainer 4, and the ball 3, the ball 3 drops slightly radially inward due to its own weight. The point where the center line passing through the contact point X between the ball 3 and the shoulder portion 6 of the outer ring intersects with the surface of the ball 3 is defined as intersection Y. The rotation angle β around the center O of the ball 3 in the direction in which the ball 3 drops from intersection Y is defined as positive, and the rotation angle β in the opposite direction from intersection Y is defined as negative. When the inner ring 2 is inserted into the outer ring assembly, its inner ring counterbore portion 9 first contacts the ball 3 at the contact point Z. If this contact point Z is on the positive rotation angle β side of the intersection Y, as will be described later (see Figure 9), the contact force with the inner ring 2 can smoothly push back the ball 3, which has fallen in under its own weight, along the outer ring raceway groove 5.

[0027] In addition, in the outer ring assembly, when the ball 3 drops radially inward due to its own weight, the size C of the ball outer contact side clearance, which is the radial clearance between the outer diameter Ro of the circumscribed circle of the ball 3 and the groove bottom of the outer ring raceway groove 5, and the size D of the ball inner contact side overlap, which is the difference between the inner diameter Ri of the ball 3 and the outer diameter Rc of the inner ring counter bore portion 9 when the inner ring 2 is inserted downward from the inner ring counter bore portion 9 side, satisfy the relationship 1.00 < C / D ≤ 2.50. Therefore, when the ball 3 that has dropped due to its own weight is pushed back along the outer ring raceway groove 5 by the contact force with the inner ring 2 (inner ring counter bore portion 9), no pressure is applied to the ball 3 and no damage or cracking occurs. Moreover, the clearance between the ball 3 and the inner and outer ring raceway grooves 5 and 8 does not become large, and the ball 3 does not ride on the inner and outer ring shoulders 6 and 10, nor does it deviate from the assumed contact angle.

[0028] An example of the operation of assembling the first angular ball bearing A and the second angular ball bearing B to an object will be described. In the following description, members with the prefix "first" are components of the first angular ball bearing A, and members with the prefix "second" are components of the second angular ball bearing B.

[0029] First, as shown in FIG. 5, the second outer ring assembly B' (which integrally holds the outer ring 1, a plurality of balls 3, and the cage 4) is fitted into the housing hole 16 provided in the object. At this time, the second outer ring assembly B' is inserted into the housing hole 16 with the counter-side annular portion 13 of the cage 4 on the upper side and the counter-side annular portion 12 on the lower side. Also, the outer ring 1 of the second outer ring assembly B' is fitted with an interference fit to the inner circumference of the housing hole 16.

[0030] Next, as shown in Figure 6, a retaining ring 18 is fitted into a retaining ring groove 17 formed on the inner circumference of the housing hole 16. This retaining ring 18 fixes the position of the outer ring 1 of the second outer ring assembly B'. Then, the first outer ring assembly A' is fitted into the portion of the housing hole 16 that is lower than the second outer ring assembly B'. At this time, the first outer ring assembly A' is inserted into the housing hole 16 with the counter-side annular portion 12 of the retainer 4 facing upwards and the non-counter-side annular portion 13 facing downwards. The outer ring 1 of the first outer ring assembly A' is then fitted to the inner circumference of the housing hole 16 with an overlap.

[0031] On the other hand, as shown in Figure 7, the first inner ring 2 is mounted on the outer circumference of the shaft 19. At this time, the first inner ring 2 is mounted on the outer circumference of the shaft with the inner ring counterbore portion 9 facing upwards and the inner ring shoulder portion 10 facing downwards. The first inner ring 2 is then fitted onto the outer circumference of the shaft 19 with an overlap. After that, the first outer ring assembly A' is mounted on the outer circumference of the first inner ring 2 from above. With this mounting, the first angular contact ball bearing A is completed. In this embodiment, since the outer diameter Rt of the tip of the inner ring counterbore portion 9 of the inner ring 2 is designed to be smaller than the inscribed circle diameter Ri of the ball 3, the first outer ring assembly A' can be smoothly mounted on the outer circumference of the first inner ring 2.

[0032] Subsequently, as shown in Figure 8, the second inner ring 2 is inserted into the second outer ring assembly B' from above, with the inner ring counterbore portion 9 facing downwards and the inner ring shoulder portion 10 facing upwards. At this time, the second inner ring 2 is fitted onto the outer circumference of the shaft body 19 with an overlap. This completes the second angular contact ball bearing B.

[0033] As described above, it is possible to assemble the first angular contact ball bearing A and the second angular contact ball bearing B onto the object.

[0034] In the insertion of the inner ring 2 in Figure 8, as shown in Figure 9, a contact force is generated at the contact point Z between the ball 3 and the inner ring 2 (inner ring counterbore portion 9), directed toward the center O of the ball. This contact force has a horizontal component F that pushes the ball 3 toward the outer ring raceway groove 5. Hand the vertical component F that pulls the ball 3 downward along the insertion direction of the inner ring 2 V can be decomposed. When this contact point Z is at the positive position of the rotation angle β with respect to the intersection point Y (the direction position where the ball 3 falls), the vertical component F V has a large horizontal component F H with respect to it, and the ball 3 can be smoothly pushed back toward the outer ring raceway groove 5.

[0035] On the contrary, as shown in FIG. 13, when the contact point Z is at the negative position of the rotation angle β with respect to the intersection point Y (the direction position opposite to the direction where the ball 3 falls), the horizontal component F H ' and the vertical component F V ' are of the same magnitude, or the vertical component F H ' is larger than the horizontal component F V ', and there is a risk that the ball 3 will be pulled in the insertion direction as the inner ring 2 is inserted, or the inner ring 2 cannot be inserted smoothly.

[0036] The main part of a modified example of the inner ring separable angular ball bearing A shown in FIG. 1 is shown in FIG. 10. This modified example is different from the above-described configuration only in that the tapered surface 11 is not formed on the inner ring counterbore portion 9. When inserting the inner ring 2 with respect to the outer ring assembly, the contact point Z where the ball 3 of this outer ring assembly and the inner ring 2 (inner ring counterbore portion 9) first come into contact is on the positive rotation angle β side with respect to the intersection point Y, and between the size C of the ball outer contact side gap and the size D of the ball inner contact side overlap, the relationship of 1.00 < C / D ≤ 2.50 is established. Therefore, in this modified example as well, as the inner ring 2 is inserted as described above, the ball 3 can be smoothly pushed back toward the outer ring raceway groove 5, and along with this pushing back, it is possible to prevent pressure from being applied to the ball 3 and causing damage or cracks, or the ball 3 from riding on the inner and outer ring shoulders 6 and 10 without achieving the assumed contact angle.

[0037] As shown in FIGS. 11 and 12, the above-described inner ring separable angular ball bearing A can be used as a bearing for an automobile transmission.

[0038] The transmission shown in Figure 11 is a fully synchronous transmission, which is a constantly meshing gear mechanism. In this transmission, the gear 30 on the input shaft side and the gear 32 on the output shaft 31 side operate in a meshed state. The shaft 33, which is rotationally driven by the input shaft and the output shaft 31, is rotatably supported by an inner-ring separated angular contact ball bearing A. This inner-ring separated angular contact ball bearing A receives not only radial loads from the input shaft or the output shaft 31, but also axial loads, which are the axial component of the force.

[0039] The transmission shown in Figure 12 is a continuously variable transmission capable of changing the speed of an automobile engine's rotation and outputting it, thereby continuously changing the gear ratio. This transmission includes a torque converter 35 connected to the crankshaft 34 of the automobile engine, an input shaft 36 to which the rotation of the automobile engine is input via the torque converter 35, an output shaft 37 provided parallel to the input shaft 36, a drive-side V-groove pulley 38 provided on the outer circumference of the input shaft 36 so as to rotate integrally with the input shaft 36, a driven-side V-groove pulley 39 provided on the outer circumference of the output shaft 37 so as to rotate integrally with the output shaft 37, and a V-belt 40 wrapped between the drive-side V-groove pulley 38 and the driven-side V-groove pulley 39. The input shaft 36 and the output shaft 37 are rotatably supported by an inner-ring separated angular contact ball bearing A. This inner-ring separated angular contact ball bearing A receives not only radial loads from the input shaft 36 or the output shaft 37, but also axial loads, which are the axial component of the force.

[0040] The embodiments disclosed herein are considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0041] 1 Outer ring 2 Inner ring 3 balls 4 Cage 5. Outer ring raceway groove 6. Outer ring shoulder 7 Outer ring counterbore section 8. Inner ring raceway groove 9 Inner ring counterbore section 10 Inner shoulder section 11 Tapered surface 15 pockets A. Separable inner ring angular contact ball bearing O center X contact point Y Intersection Z contact point α Tilt angle β rotation angle

Claims

1. Outer ring (1) and, An inner ring (2) is arranged coaxially on the radially inward side of the outer ring (1), Multiple balls (3) are incorporated between the outer ring (1) and the inner ring (2) at circumferential intervals, The system comprises a holder (4) that holds the plurality of balls (3), The inner circumference of the outer ring (1) is provided with an outer ring raceway groove (5) into which the ball (3) rolls and makes contact, an outer ring shoulder (6) adjacent to one side of the outer ring raceway groove (5) in the axial direction, and an outer ring counterbore (7) adjacent to the other side of the outer ring raceway groove (5) in the axial direction and having a larger inner diameter than the outer ring shoulder (6). The outer circumference of the inner ring (2) is provided with an inner ring raceway groove (8) in which the ball (3) rolls and makes contact, an inner ring counterbore portion (9) adjacent to one side of the inner ring raceway groove (8) in the axial direction, and an inner ring shoulder portion (10) adjacent to the other side of the inner ring raceway groove (8) in the axial direction and having a larger outer diameter than the inner ring counterbore portion (9). In an inner ring separation type angular contact ball bearing, in which the balls (3) are supported so as not to fall radially inward from the pockets (15) formed in the retainer (4) when the inner ring (2) is separated, With the outer ring (1), the retainer (4), and the ball (3) held integrally, when the ball (3) falls radially inward due to its own weight, the point where the center line passing through the contact point (X) between the ball (3) and the shoulder portion (6) of the outer ring intersects the surface of the ball (3) is defined as the intersection (Y), and when the rotation angle (β) around the center (O) of the ball (3) in the direction in which the ball (3) falls from this intersection (Y) is defined as positive, and the rotation angle (β) in the opposite direction from the intersection (Y) is defined as negative, the contact point (Z) where the ball (3) and the inner ring counterbore portion (9) first come into contact when the inner ring (2) is inserted downward from the inner ring counterbore portion (9) side is located on the positive side of the intersection (Y). As the inner ring (2) contacts the positive rotation angle (β) side of the intersection (Y), the ball (3) that has fallen in due to its own weight is pushed back along the outer ring raceway groove (5). A tapered surface (11) is formed on the outer circumferential surface side of the inner ring counterbore portion (9), such that the outer diameter gradually decreases as it moves away from the inner ring raceway groove (8). An inner ring separation type angular contact ball bearing characterized in that an axially flat counter flat portion is formed between the inner ring raceway groove (8) and the tapered surface (11), and the counter flat portion is continuous with the groove bottom of the inner ring raceway groove (8).

2. The inner ring separation type angular contact ball bearing according to claim 1, wherein the axial inclination angle α of the tapered surface (11) satisfies 0° < α ≤ 30°.

3. An inner ring-separated angular contact ball bearing according to claim 1 or 2, used as a bearing for an automobile transmission.

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